[0001] This invention relates to papermaking, particularly closed loop fabrics used to support
and carry cellulosic pulp fibers as they move through the papermaking process. This
invention relates specifically to closed loop felts e.g. used in what is known as
the press section of the paper machine between the forming fabric and the drying section.
[0002] In general, a paper machine includes a forming section where a thin slurry of e.g.
water and fiber are expressed onto a relatively permeable closed loop forming fabric,
also known as a fourdrinier fabric. Free water drains through the forming fabric,
leaving a more or less consolidated matt of the fibers on the forming fabric.
[0003] From the forming fabric, the consolidated, but still quite wet, matt of fibers is
transferred to a papermaking felt. Like the forming fabric, the felt is configured
as a closed loop. Typically, the felt carries the consolidated matt of fibers of the
web being formed through a press section, where additional water is removed from the
matt by mechanically squeezing.
[0004] A typical felt comprises a substrate having opposing major surfaces, and one or more
batts of fibrous material needled into, or otherwise assembled to, the opposing major
surfaces of the substrate. In making the felt, typically the substrate is first woven
in a closed loop configuration. More than one substrate web can be used to form the
internal structure of the substrate, after which the batts of fibrous material are
needled into the substrate from the opposing major surfaces of the substrate.
[0005] Depending on the configuration, the composition, and the spacing of the batt fibers,
the fibers perform a variety of functions, including influencing the rate of removal
of water from the web of paper being formed, and at least influencing the final surface
texture of the paper web being formed.
[0006] From the felt, the web of paper being formed typically passes into the dryer section
of the paper machine, and thence to the winder where the formed and dried web of paper
is wound onto a roll.
[0007] In any web of paper being formed, the texture and other surface properties are influenced
by texture and other surface properties of the felt. Such surface properties, as well
as the interior characteristics such as the overall density and water drainage properties
should be uniform. Variations in either the substrate web or the fibers needled into
the substrate web are typically reflected in the paper web made with the felt.
[0008] Substantial efficiencies are realized as processing speeds are increased in paper
making, and in paper converting, processes. In such processes, it is critical that
the paper user, or paper converter, be able to rely on uniformity, both along the
length and along the width, of the paper web produced at the paper machine.
[0009] Accordingly, in making the closed loop felt, the felt should present, to the web
being formed into a web of paper, physical properties that are functionally uniform
about the entire area of the surface of the felt which contacts the web.
[0010] Various methods are known for fabricating the felt as an endless loop. For example,
United States Patent 4,737,241 Gulya teaches a method using a pin joint to close the
loop, across the width of the web, in a previously-formed substrate web having opposing
first and second ends. The areas at and immediately adjacent to the pin joint, by
their very nature, have structural and thus physical properties that differ somewhat
from the properties associated with the remainder of the felt. In all cases, such
pin joint felts carry at least the potential that the different properties at the
pin joint might be transferred to the paper web manufactured with such felts.
[0011] It is known to weave the substrate web for the felt as a closed loop on a shuttle
loom appropriately designed for such closed loop weaving. In conventional felts, the
closed loop weaving process is often preferred because the felt is fabricated as a
closed loop having no ends. Such a felt has no joint across its width, and correspondingly
no potential for variation of the properties in the felt at the joint.
[0012] While a felt fabricated as a closed loop is superior to pin joint felts in that there
is no cross-directional joint, weaving a felt substrate web in a closed loop configuration
entails significant set-up cost which may be attenuated by weaving a substrate web
precursor as a flat fabric, and subsequently forming the flat-woven fabric into an
endless loop in a fuse bonding process.
[0013] In general, weaving includes a first step of threading an array of warp threads into
the weaving machine, followed by the actual thread-by-thread interdigitation of the
weft threads into the array of warp threads as the warp threads are advanced past
the shuttle or other carrier of weft thread. Compared to flat-woven fabrics, the process
of incorporating threads into a fabric being woven in a closed loop configuration
is in general slower than flat weaving the same fabric.
[0014] Overlooking for the moment the issue of fabricating the substrate web into a closed
loop, it is entirely possible for a felt manufacturer to predict with reasonable accuracy
the weave patterns and materials of substrate webs which will be needed for manufacturing
purposes in the near term future e.g. six months or less. It is much more difficult
to predict the length and width requirements of the specific felts which will need
to be manufactured in the near term future. Until the length and width requirements
of a particular felt are known, it is generally not feasible to begin set-up or weaving
of a closed loop substrate web.
[0015] Accordingly, the entire process of assembling a felt, including weaving of the substrate
web is typically delayed until the manufacturer receives the length and width specifications
for the finished felt. As a result, where a pin-joint felt is not acceptable, felt
manufacturers are effectively precluded from stockpiling standard woven substrate
web materials. They must wait for the customer's specifications and order.
[0016] While the felt needed for any given paper machine is typically unique to that machine,
most felt substrates incorporate one or more of a relatively small number of weave
patterns, using threads according to one or more of a relatively small number of types
of materials and/or threads. Thus, in principle, if it were feasible to form the flat-woven
substrate web precursor material into a closed loop configuration after manufacture
of the substrate web precursor material, the felt manufacturer could reasonably flat
weave, and stockpile in e.g. roll form, a variety of the more common substrate web
precursor materials in e.g. a relatively small number of weave patterns and materials,
against anticipated but not yet received orders.
[0017] Such pre-manufacture of the substrate web material would carry attendant cost advantages
associated with longer weaving runs without intervening set-up costs, and shorter
lead times between receipt of the order and shipment of the finished felt. The felt
manufacturer could stockpile a supply of standard substrate webs, and draw appropriate
substrate web precursor material from the stockpiled rolls when an order is received.
[0018] It is an object of the invention to provide a novel woven felt substrate web, and
a felt made therewith, the substrate web having a fuse bonded joint extending across
the width of the substrate web, the joint having an outer surface, and texture in
the surface, along the width of the web, corresponding with the pattern of the weave.
[0019] It is another object of the invention to provide a novel woven felt substrate web,
and a felt made therewith, the substrate web having a fuse bonded joint extending
across the width of the substrate web, the joint having minimal, if any, residual
elements of a crown on one surface of the substrate web, and minimal, if any, residual
elements of a valley on the opposing surface.
[0020] Desirably, in a preferred papermaking felt having a substrate web, and a joint in
the substrate web, the machine direction tensile strength generally along the length
of the substrate web is relatively greater than the machine direction tensile strength
at the joint.
[0021] Preferably, the papermaking felt, includes first and second substrate web elements
in face-to-face relation with each other, each having a transverse joint, with the
joints spaced from each other.
[0022] A further object is to provide a novel method of making a papermaking felt from a
flat-woven precursor web, including severing a web element, and forming the web into
a closed loop with a fuse bonded joint.
[0023] According to the invention, a method of making a papermaking felt from a flat-woven
precursor web, includes the steps of severing a web element, superposing end portions
of the web element on each other, and fuse-bonding the ends of the web element to
each other.
[0024] Steps in such a method of making a papermaking felt from a flat-woven pecursor web
can, incude severing a web element, superposing end portions of the web element on
each other, severing the ends, fuse-bonding the ends to each other, rotating the edge
portions about the fuse-bonded ends, and assembling batts of fibrous material to opposing
surfaces of the substrate web so formed.
[0025] A preferred method embodying the invention can involve fabricating at least first
and second substrate web precursors, subsequently specifying the properties of the
felt and selecting one of the substrate web precursors, severing a substrate web element
from the selected precursor, and forming a fuse-bonded joint in the web precursor
to make the closed loop substrate web.
[0026] A still further object of the invention is to provide a novel method of making paper,
using a felt with a crown, wherein the crown is displaced from the surface which receives
the paper web being formed.
[0027] The invention can be embodied in a method of making a papermaking felt including
weaving a substrate web precursor on a shuttle-less loom, severing a web element from
the precursor, fuse-bonding ends of the web element to each other to make the web
element into a closed loop configuration comprising the substrate web, and then assembling
batts of fibrous material to opposing surfaces of the substrate web.
[0028] Some of the objects are obtained in a first family of embodiments comprehending a
substrate web for use in making a papermaking felt, the substrate web circumscribing
a closed loop path and having a length along the closed loop path, and a width transverse
to the length. The substrate web generally defines first and second opposing surfaces
along the length thereof, and comprises woven threads extending along the length and
width of the substrate web; and a joint extending in a direction transverse to the
length of the substrate web, the joint comprising fused elements of ones of the woven
threads, fused to each other at spaced locations along the width of the substrate
web, the joint having an outer surface, and texture in the surface, along the width
of the substrate web, corresponding with the pattern of the weave.
[0029] In typical embodiments, the joint has a first tensile strength along the direction
of the length of the substrate web, the substrate web having a second general tensile
strength generally distributed along the length thereof at loci displaced from the
joint. The second general tensile strength is greater than the first tensile strength,
preferably at least 50% greater than the first tensile strength, more preferably at
least twice, and up to at least three times as great, as the first tensile strength.
[0030] Preferably, the woven threads comprise materials selected from the group consisting
of nylon, polyester, and polyurethane. In preferred embodiments, the woven threads
comprise a first set of threads extending along the length of the substrate web and
a second set of threads extending along the width of the substrate web, the joint
comprising fused ends of ones of the threads in the first set.
[0031] Preferably, the joint extends across substantially the entirety of the width of the
substrate web.
[0032] The invention includes a second family of embodiments comprehending a substrate web
for use in making a papermaking felt, the substrate web circumscribing a closed loop
path and having a length along the closed loop path, and a width transverse to the
length. The substrate web generally defines first and second opposing surfaces along
the length thereof, and comprises woven threads extending along the length and width
of the substrate web; and a joint extending in a direction transverse to the length
of the substrate web, the joint comprising a crown on the first surface and a corresponding
valley on the second surface.
[0033] In typical embodiments, the joint has a first tensile strength along the direction
of the length of the substrate web, the substrate web has a general tensile strength
generally distributed along its length at loci displaced from the joint. The second
general tensile strength is greater than the first tensile strength, preferably at
least 50% greater than the first tensile strength, more preferably at least twice
as great as the first tensile strength.
[0034] Preferably, the woven threads comprise materials selected from the group consisting
of nylon, polyester, and polyurethane. In preferred embodiments, the joint comprises
fused ends of ones of the woven threads, the fused ends being disposed on ones of
the threads which extend along the length of the substrate web, the ends being fused
to each other at spaced locations along the joint, the joint having an outer surface,
and texture in the surface, along the width of the substrate web, corresponding with
the pattern of the weave.
[0035] Preferably, the joint extends across substantially the entirety of the width of the
substrate web.
[0036] The invention includes a third family of embodiments comprehending a papermaking
felt circumscribing a closed loop path, the papermaking felt having a first length
along the closed loop path and a first width transverse to the first length, a first
surface for contacting and carrying a web of paper being formed with the papermaking
felt, and a second opposing surface, the papermaking felt comprising a substrate web,
having third and fourth opposing surfaces, a second length and a second width, the
substrate web having woven threads extending along the second length and the second
width of the papermaking felt, and a joint extending transverse to the second length,
the joint comprising fused elements of ones of the woven threads, fused to each other
along the second width, the joint exhibiting a first tensile strength along the second
length, the substrate web having a second general tensile strength generally distributed
along the second length at loci displaced from the joint, the second general tensile
strength being greater than the first tensile strength; and first and second batts
of fibrous material assembled in the papermaking felt on the first and second opposing
surfaces.
[0037] Preferred embodiments of the papermaking felt are adapted to process substantially
any type of paper web without leaving on the paper web any mark, detectable by unaided
visual observation, indicating the presence of the joint.
[0038] Preferably, the second tensile strength is at least 50% greater than the first tensile
strength, more preferably at least twice, and up to at least three times as great
as the first tensile strength.
[0039] In preferred embodiments, the substrate web comprises a first substrate web, the
joint comprises a first joint, the papermaking felt including a second substrate web
having fifth and sixth opposing surfaces, a third length and a third width, second
woven threads extending along the third length and the third width, and a second joint
extending transverse to the third length, the second joint exhibiting a third tensile
strength along the third length, the second substrate web having a fourth general
tensile strength generally distributed along the third length at loci displaced from
the second joint, the fourth tensile strength being greater than the third tensile
strength, the first and second substrate webs being disposed in face-to-face relationship
with each other over substantially the entirety of ones of the surfaces of the respective
substrate webs, the first and second joints being spaced from each other. Preferably,
the first and second joints are spaced from each other by at least 25% of the first
length.
[0040] In other ones of this third family of embodiments, the substrate web comprises a
first substrate web including the joint, and includes a second endless woven substrate
web having fifth and sixth opposing surfaces, the first and second substrate webs
being disposed in face-to-face relationship with each other over substantially the
entirety of ones of the surfaces of the respective first and second substrate webs.
[0041] The woven threads preferably comprise materials selected from the group consisting
of nylon, polyester, and polyurethane.
[0042] In preferred embodiments of this third family, the respective joints comprise ends
of ones of the woven threads fused to each other at locations spaced along the second
width of the substrate web, each joint having an outer surface, the respective outer
surface having a texture, along the width of the substrate web, corresponding with
the pattern of the weave. Each joint typically comprises a crown on the third surface
and a corresponding valley on the fourth surface. The first substrate web may be disposed
at the first surface, with the first substrate web oriented such that the crown is
directed away from the first surface.
[0043] In some embodiments, the joint comprises a first joint, the substrate web comprises
a first substrate web, and the felt includes a second substrate web having fifth and
sixth opposing surfaces, a third length and a third width, the second substrate web
having second woven threads extending along the third length and the third width of
the second substrate web, and a second joint extending transverse to the third length,
the second joint comprising fused elements of ones of the second woven threads, fused
to each other along the third width, the second joint comprising a second crown on
the fifth surface and a corresponding second valley on the sixth surface. Preferably,
the second crown is directed away from the first surface. Also preferably, the joint
extends along the entirety of the closed loop path, and across substantially the entirety
of the second width of the substrate web.
[0044] In a fourth family of embodiments, the invention comprehends a papermaking felt circumscribing
a closed loop path, the papermaking felt having a first length along the closed loop
path and a first width transverse to the first length, a first surface for contacting
and carrying a web of paper being formed with the papermaking felt, and a second opposing
surface, the papermaking felt comprising a first substrate web, having third and fourth
opposing surfaces, a second length and a second width, the first substrate web having
first woven threads extending along the second length and the second width, and a
first joint on the first substrate web, extending transverse to the second length,
the first joint comprising a first crown on the third surface and a corresponding
first valley on the fourth surface; a second substrate web disposed in facing relationship
adjacent the first substrate web, and having fifth and sixth opposing surfaces, a
third length and a third width, the second substrate web having second woven threads
extending along the third length and the third width, and a second joint on the second
substrate web, extending transverse to the third length, the second joint comprising
a second crown on the fifth surface and a corresponding second valley on the sixth
surface; and first and second batts of fibrous material assembled in the papermaking
felt on the first and second opposing surfaces.
[0045] Preferably, the first substrate web is disposed at the first surface and is oriented
such that the first crown is directed away from the first surface.
[0046] In some embodiments, the second substrate web is oriented such that the second crown
is directed away from the first surface.
[0047] In other embodiments, the second substrate web is oriented such that the second crown
is directed toward the first substrate web.
[0048] The subject papermaking felts containing first and second substrate webs are typically
adapted to process substantially any type of paper web without leaving on the paper
web any mark, detectable by unaided visual observation, indicating the presence of
either of the first and second joints.
[0049] Also typically, the first and second joints are spaced from each other by at least
25% of the first length.
[0050] Preferably, the first and second woven threads comprise materials selected from the
group consisting of nylon, polyester, and polyurethane.
[0051] In a fifth family of embodiments, the invention comprehends a method of making a
papermaking felt circumscribing a closed loop path, the papermaking felt comprising
a substrate web, the papermaking felt having opposing first and second surfaces, and
first and second batts of fibrous material assembled to the first and second surfaces,
the papermaking felt having a first length along the closed loop path and a first
width extending transverse to the length, the substrate web having opposing third
and fourth surfaces. The method comprises the steps of fabricating a flat-weave substrate
web precursor, the flat-weave substrate web precursor having a second length, preferably
at least as great as the first length, and a second width transverse to the second
length; severing, from the flat-weave substrate web precursor, a substrate web element
having a third length, and a third width transverse to the third length, first and
second ends, and corresponding first and second edges; forming the substrate web element
into a closed loop path, and thereby fabricating the substrate web, by joining the
first and second ends, with at least one fuse-bonded transverse joint extending between
the first and second edges in a direction transverse to the length; and securing a
batt of fibrous material to at least one of the third and fourth surfaces.
[0052] The substrate web may comprise at least two substrate web elements, joined by corresponding
at least first and second joints transverse to the third length, the closed loop path
extending a distance of at least about 25% of the first length between the first and
second joints.
[0053] In some embodiments, the method comprises severing first and second substrate web
elements from at least one flat weave substrate web precursor, each such substrate
web element having first and second ends, forming the substrate web into a closed
loop path by joining the first end of the first substrate web element to the second
end of the second substrate web element, to form a first joint, by joining the first
end of the second substrate web element to the second end of the next substrate web
element to form a second joint, and by so joining the first end of each substrate
web element to the second end of the succeeding substrate web element, and forming
a corresponding joint, with the first end of the last substrate web element being
joined to the second end of the first substrate web element.
[0054] The method may comprise joining the first and second ends, to form the at least one
transverse joint by fuse bonding members of the substrate web element to each other
at locations spaced along the third width of the substrate web element, the joint
having an outer surface, and texture in the outer surface, along the width of the
substrate web, corresponding with the pattern of the weave, each joint preferably
describing an angle of at least 45 degrees with an axis extending parallel to the
second length.
[0055] Preferred methods include joining the first and second ends, to form the at least
one transverse joint by superposing first and second end portions of the respective
substrate web element adjacent the first and second ends, with the first and second
end portions extending away from the respective first and second ends in a common
direction, severing the substrate web element through both of the first and second
end portions across the third width proximate the first and second ends to form a
new first end and a new second end, and fuse bonding the new first end and the new
second end to each other to form the joint while the first and second end portions
are so superposed with respect to each other, thus forming the substrate web element
into the substrate web, rotating the first and second end portions about the fuse-bonded
joint such that the first and second end portions extend generally away from each
other, with the joint forming a crown on the first surface and a valley on the second
surface.
[0056] The method preferably includes reducing the prominence of the crown and the prominence
of the valley such that paper made with the papermaking felt carries no mark, detectable
by unaided visual observation, indicating the presence of the joint. A preferred method
of reducing the prominence of the crown and the valley includes needling a batt of
fibrous material to at least one of the first and second surfaces subsequent to rotating
the first and second end portions about the fuse-bonded joint.
[0057] The method preferably includes concurrently severing and fuse bonding the substrate
web element at the first and second end portions, proximate the first and second ends,
by applying ultrasonic energy to the first and second end portions at a corresponding
severing locus, preferably including applying the ultrasonic energy to the substrate
web element by advancing the severing locus across the third width.
[0058] In a sixth family of embodiments, the invention comprehends a method of making a
papermaking felt circumscribing a closed loop path, the papermaking felt comprising
a closed loop substrate web, the papermaking felt having opposing first and second
surfaces, and first and second batts of fibrous material assembled to the papermaking
felt at the first and second surfaces, the papermaking felt having a first length
along the closed loop path, and a first width extending transverse to the length,
the substrate web having a second length, and a second width transverse to the second
length, and opposing third and fourth surfaces, the method comprising the steps of
fabricating a substrate web precursor having first and second ends, a third length,
and a third width; severing, from the substrate web precursor, a substrate web element
having a fourth length, and a fourth width transverse to the fourth length, and third
and fourth ends; superposing first and second end portions of the substrate web element
adjacent the third and fourth ends, with the third and fourth ends generally aligned
with each other and the first and second end portions extending away from the respective
third and fourth ends in a common direction; severing the substrate web element across
the fourth width proximate the third and fourth ends, thus forming a new third end
and a new fourth end, while the first and second end portions are superposed with
respect to each other, whereby the respective first and second end portions extend
away from the new third end and the new fourth end in the common direction; fuse bonding
the new third end and the new fourth end to each other to form a fuse-bonded joint
while the first and second end portions are so superposed with respect to each other,
thus forming the substrate web element into the closed loop substrate web having a
fuse-bonded joint extending across the second width; rotating the first and second
end portions about the fuse-bonded joint such that the first and second end portions
generally extend away from each other, with the fuse-bonded joint forming a crown
on the third surface and a valley on the fourth surface; assembling the first batt
of fibrous material to the substrate web at the third surface to make a papermaking
felt subassembly, and such that the first batt of fibrous material thereon corresponds
with the first surface of the papermaking felt; and assembling the second batt of
fibrous material to the subassembly such that the second batt of fibrous material
corresponds with the second surface of the papermaking felt.
[0059] In preferred embodiments, the assembling of the first and second batts into the papermaking
felt subassembly is effective to reduce the prominence of the crown and the prominence
of the valley such that a paper made with the closed loop path papermaking felt can
be made to carry no mark, detectable by unaided visual observation, indicating the
presence of the joint.
[0060] The method preferably includes performing the severing and fuse bonding steps concurrent
with each other.
[0061] In some embodiments, the method comprises joining the new third end and the new fourth
end, to form the fuse-bonded joint by fusing members of the substrate web element
to each other at locations spaced along the fourth width such that the joint comprises
surface texture along the second width.
[0062] Preferably, the joint describes an angle of at least 45 degrees with an axis extending
parallel to the second length.
[0063] In some embodiments, the method includes reducing the prominence of the crown and
the prominence of the valley such that paper made with the papermaking felt can be
made to carry no mark, detectable by unaided visual observation, indicating the presence
of the joint.
[0064] Preferred methods include concurrently performing the severing and fuse bonding in
steps by applying ultrasonic energy to the first and second end portions at a corresponding
severing locus, preferably including applying the ultrasonic energy to the substrate
web element by advancing an ultrasonic device across the fourth width.
[0065] In a seventh family of embodiments, the invention comprehends a method of making
a papermaking felt circumscribing a closed loop path, the papermaking felt comprising
a closed loop substrate web, the papermaking felt having opposing first and second
surfaces, and first and second batts of fibrous material assembled to the papermaking
felt at the first and second surfaces, the papermaking felt having a first length
along the closed loop path, and a first width extending transverse to the first length,
the substrate web having a second length, and a second width transverse to the second
length, and opposing third and fourth surfaces. The method comprises the steps of
fabricating a substrate web precursor, having a third length and a third width, and
fifth and sixth opposing surfaces, by weaving threads extending along the third length
and the third width; severing, from the substrate web precursor, a substrate web element
having a fourth length, and a fourth width transverse to the fourth length, and first
and second ends and corresponding first and second edges; superposing first and second
end portions of the substrate web element adjacent the first and second ends, with
the first and second ends generally aligned with each other and the first and second
end portions extending away from the respective first and second ends in a common
direction; fuse bonding the first and second end portions to each other at the first
and second ends, to form a fuse-bonded joint at the first and second ends while the
first and second end portions are so superposed with respect to each other, thus forming
the substrate web element into the closed loop substrate web having a fuse-bonded
joint extending across the substrate web; and assembling fibrous batt material to
at least one of the first and second surfaces.
[0066] Preferred embodiments include the step, performed simultaneously with the fuse-bonding
step, of cutting the substrate web element across the fourth width proximate the first
and second ends, thus forming a new first end and a new second end adjacent the respective
first and second ends, and thereby making a new cut in the substrate web element in
each of the first and second end portions concurrent with fuse bonding the end portions
to each other at the new first end and the new second end.
[0067] In preferred embodiments, the substrate web element has a fourth length, and a fourth
width extending transverse to the fourth length, and the method comprises joining
the first and second ends, to form the at least one transverse joint by fuse bonding
members of the substrate web element to each other at locations spaced along the fourth
width of the substrate web element, the joint having an outer surface, and texture
in the outer surface corresponding with the pattern of the weave.
[0068] The joint formed by the method preferably describes an angle of at least 45 degrees
with an axis extending parallel to the fourth length.
[0069] In preferred embodiments, the method includes severing the substrate web element
through both of the first and second end portions across the fourth width proximate
the first and second ends to form a new first end and a new second end, and fuse bonding
the new first end and the new second end to each other to form the fuse-bonded joint,
and correspondingly the substrate web, while the first and second end portions are
so superposed with respect to each other, rotating the first and second end portions
about the fuse bonded joint such that the first and second end portions extend generally
away from each other, with the joint forming a crown on the third surface and a valley
on the fourth surface. The method preferably includes reducing the prominence of the
crown and the prominence of the valley such that paper made with the papermaking felt
can be made to carry no mark, detectable by unaided visual observation, indicating
the presence of the joint, preferably by needling a batt of fibrous material to at
least one of the third and fourth surfaces. The severing to form new first and second
ends typically includes severing surplus material from the first and second end portions.
[0070] Preferred embodiments include concurrently severing and fuse bonding the substrate
web element at the first and second end portions by applying ultrasonic energy to
the first and second end portions at a corresponding severing locus, the method including
applying the ultrasonic energy to the substrate web element by advancing an ultrasonic
device across the fourth width. Preferably, the fuse-bonded joint extends across the
entirety of the substrate web, from the first edge to the second edge.
[0071] In an eighth family of embodiments, the invention comprehends a method of making
a papermaking felt circumscribing a closed loop path, the papermaking felt comprising
a closed loop substrate web, the papermaking felt having opposing first and second
surfaces, and first and second batts of fibrous material assembled to the papermaking
felt at the first and second surfaces, the papermaking felt having a first length
along the closed loop path, and a first width transverse to the first length, the
substrate web having a second length, and a second width transverse to the second
length, and opposing third and fourth surfaces. The method comprises the steps of
fabricating first and second flat-woven substrate web precursors having first and
second sets of properties, differing from each other, the first substrate web precursor
having a third length, and a third width transverse to the third length, the second
substrate web precursor having a fourth length, and a fourth width transverse to the
fourth length; subsequent to fabricating the first and second flat-woven substrate
web precursors, specifying properties of the papermaking felt to be made; selecting,
according to the properties specified for the papermaking felt to be made, a preferred
one of the first and second flat-woven substrate web precursors, for making the papermaking
felt; severing a substrate web element from the selected one of the first and second
flat-woven substrate web precursors to appropriate fifth length and fifth width according
to the properties specified for the papermaking felt to be made, whereby the substrate
web element so made has first and second edges extending along the fifth length, corresponding
first and second ends extending across the fifth width, and fifth and sixth opposing
surfaces; superposing first and second end portions of the substrate web element adjacent
the first and second ends, with the first and second ends generally aligned with each
other and the first and second end portions extending away from the respective first
and second ends in a common direction; fuse bonding the first and second ends to each
other to form a fuse-bonded joint while the first and second end portions are so superposed
with respect to each other, thus forming the substrate web element into the closed
loop substrate web having the second length and the second width, and the opposing
third and fourth surfaces, and a fuse-bonded joint extending across the substrate
web between the first and second edges; and assembling a batt of fibrous material
to at least one of the third and fourth surfaces.
[0072] Preferred embodiments include the step, performed simultaneously with the fuse-bonding
step, of cutting the substrate web element across the fifth width proximate the first
and second ends, thus forming a new first end and a new second end adjacent the respective
first and second ends, and thereby making a new cut in the substrate web element in
each of the first and second end portions concurrent with fuse bonding the end portions
to each other at the new first end and the new second end.
[0073] In preferred embodiments, the method comprises joining the first and second ends,
to form the joint by fuse bonding members of the substrate web element to each other
at locations spaced along the fifth width of the substrate web element, the joint
having an outer surface, and texture in the outer surface corresponding with the pattern
of the weave.
[0074] The joint formed by the method preferably describes an angle of at least 45 degrees
with an axis extending parallel to the second length.
[0075] In preferred embodiments, the method includes severing the substrate web element
through both of the first and second end portions across the fifth width proximate
the first and second ends to form a new first end and a new second end, and fuse bonding
the new first end and the new second end to each other to form the fuse-bonded joint,
and correspondingly the substrate web, while the first and second end portions are
so superposed with respect to each other, rotating the first and second end portions
about the fuse-bonded joint such that the first and second end portions extend generally
away from each other, with the joint forming a crown on the third surface and a valley
on the fourth surface. The method preferably includes reducing the prominence of the
crown and the prominence of the valley such that paper made with the papermaking felt
can be made to carry no mark, detectable by unaided visual observation, indicating
the presence of the joint, preferably by needling a batt of fibrous material to at
least one of the third and fourth surfaces. The severing to form new first and second
ends typically severs surplus material from the first and second end portions.
[0076] In a ninth family of embodiments, the invention comprehends a method of making paper
on a continuous-process paper machine, the paper machine including a forming fabric
circumscribing a first closed loop path and a papermaking felt circumscribing a second
closed loop path, the papermaking felt having a first surface for receiving thereon
a web of paper being formed on the paper machine, and an opposing second surface remote
from the first surface, the method comprising employing, as the continuous loop felt,
a felt having a first length, a first width, and comprising a substrate web and first
and second batts of fibrous material assembled to opposing third and fourth surfaces
of the substrate web, the third and fourth surfaces of the substrate web generally
corresponding to the first and second surfaces of the felt, the substrate web comprising
at least one substrate web element having fifth and sixth opposing surfaces and extending
about the second closed loop path, the at least one substrate web element comprising
a joint extending across the first width, the joint having a crown on the fifth surface
and a corresponding valley on the sixth surface, the method including orienting the
papermaking felt with respect to the paper machine such that the crown is displaced
from the first surface.
[0077] Preferably, the fifth surface, and thus the crown, is directed away from the first
surface.
[0078] Preferred embodiments of the invention will now be described by way of example only
with reference to and as shown in the accompanying drawings, in which:
FIGURE 1 shows a representative schematic side elevation of a paper machine.
FIGURE 2 shows a cross-section of a typical felt having a single-layer substrate web.
FIGURE 3 shows a cross-section of a typical felt having a two-layer substrate web.
FIGURE 4 shows a cross-section of the single-layer substrate web of FIGURE 2.
FIGURE 5 shows a roll of flat-woven substrate web precursor material of the invention,
with a portion unrolled and marked for cutting a substrate web element therefrom.
FIGURE 6 shows a pictorial side representation of apparatus for severing and fuse-bonding
the substrate web element, to make a joint.
FIGURE 7 shows a pictorial view of the apparatus of FIGURE 6, with indicators showing
advance of the severing and fuse-bonding locus, to form the substrate web element
into a closed loop substrate web.
FIGURE 8 is an enlarged edge view of a portion of the substrate web of FIGURE 7, showing
the severed and fuse-bonded joint.
FIGURE 9 is an end view of the end portions of the fuse-bonded substrate web of FIGURE
7, illustrating texture in the surface of the joint.
FIGURE 10 is a simplified representation of an edge view of the substrate web of FIGURE
8, showing rotation of the end portions, and corresponding creation of a crown, and
a respective valley, at the joint.
FIGURE 11 is a cross-section of a portion of the substrate web of FIGURE 10, showing
the joint after batts of fibrous material have been needled to the substrate web.
FIGURE 12 is a pictorial schematic representation illustrating multiple joints in
a substrate web.
FIGURE 13 is an enlarged representation of an elevation view showing a single layer
felt of the invention in the press section of a paper machine, with the crown displaced
from the surface of the felt which carries the paper web.
FIGURES 14-16 are schematic representations of felts of the invention, incorporating
at least two substrate webs.
[0079] Before explaining at least one embodiment of the invention in detail, it is to be
understood that the invention is not limited in its application to the details of
construction and the arrangement of the components set forth in the following description
or illustrated in the drawings. The invention is capable of other embodiments or of
being practiced or carried out in various ways. Also, it is to be understood that
the terminology and phraseology employed herein is for purpose of description and
illustration and should not be regarded as limiting. Like reference numerals are used
to indicate like components.
[0080] Referring now by characters of reference to the drawings, and first to FIGURE 1,
in general, a continuous process paper machine 10 typically includes a forming section
12, a press section 14, a drying section 16, and a wind-up 18. In general, a thin
slurry of e.g. water and pulp fibers is expressed from a headbox slice 20 at the forming
section 12 onto the closed loop forming fabric 24. Free water is drained from the
slurry in the forming section, leaving a wet matt of fibers on the forming fabric.
The wet matt of fibers is transferred from the forming fabric to a closed loop papermaking
felt 26, and thus transferred to the press section 14.
[0081] In the press section, additional water is removed from the wet matt of pulp fibers.
In a first mechanism, water is removed from the matt of pulp fibers in the press section
by capillary drawing action of fibrous material on the surface 28 of the felt 26,
which surface contacts the web of paper being formed, drawing water from the matt
of pulp into the interstices of the felt. In a second mechanism, the felt 26, with
the now-consolidated, but still wet, web of paper 22 thereon, passes through a nip
30 at a pair of press rolls 32A and 32B, where additional water is forced, by mechanical
squeezing, from both the web of paper and the felt.
[0082] From the press section, the web of paper is transferred to the dryer 16 where additional
water is removed typically by a phase change mechanism, such as by heating the web
to thus vaporize water contained therein.
[0083] From the dryer, the web of paper 22 is wound up on a wind-up roll 34 in wind-up section
18.
[0084] The above is a general description of paper making apparatus and process. Those skilled
in the art will recognize that there are many variations on the basic concepts for
papermaking described above. The description above should be taken as illustrative
only, for use only as an assist in understanding the invention as described more fully
hereinafter. Thus, the above description is not limiting as to papermaking apparatus
or processes with which the invention disclosed herein may be practiced.
[0085] The invention herein addresses the papermaking felt 26, its structure, methods of
making the felt, and methods of using the felt.
[0086] FIGURES 2 and 3 show general cross section representations of papermaking felts.
In general, a felt 26 embodies a closed loop configuration, as illustrated in FIGURE
1. The felt has a length, defined about the closed loop configuration, a width transverse
to the length, a first web carrying surface 28 for receiving and carrying the web
of paper being formed in the paper machine, and a second roll-side surface 34 opposite
the first surface. The felt is constructed of a substrate 35 having at least one substrate
web 36, and one or more batts 38, 40 of fibrous material assembled to the substrate
on the opposing respective surfaces 28, 34.
[0087] FIGURE 2 represents a felt having a substrate web 35 comprising a single woven substrate
web 36, whereby the substrate 35A comprises a single woven substrate web. FIGURE 3
represents a felt having a substrate 35B comprising two woven substrate webs 36A and
36B.
[0088] FIGURE 4 illustrates a typical woven substrate web used, either alone or in combination
with one or more additional substrate webs to form the substrate 35. As seen therein,
a substrate web 35 generally comprises a plurality of warp threads 44 woven with weft
threads 46.
[0089] The invention herein can be practiced with a wide variety of weave patterns, whereby
the weave pattern, in general, is of minimal if any significance to the invention.
[0090] The invention can be practiced with any known thermoplastic material used to form
substrate webs 36. Preferred materials are selected from nylons, polyesters and polyurethanes.
The desirability and availability of other thermoplastic materials is known to those
skilled in the art, and same are contemplated for use with the invention disclosed
here so long as the other properties of the substrate web, not specifically dependent
on this invention, are satisfied.
[0091] A variety of thread structures are known for use in making substrate webs 36, for
example various twisted, braided, etc. thread structures. The invention can be practiced
with any of such known thread structures, and related such thread structures developed
in the future are contemplated as being useful with the invention herein, whether
warp threads or weft threads.
[0092] It is common to weave the substrate 35, whether one substrate web 36 or more than
one substrate web 36, on a shuttle loom, and to weave the substrate 35 in a continuous
weave, closed loop configuration, such that the substrate 35 comprises a closed loop
at the time it is removed from the loom.
[0093] In the invention herein, a substrate web element precursor 48 is woven in a flat
weave configuration, wherein the substrate web element precursor, as woven, has first
and second opposing surfaces 49, 51, a length "L1" (not shown), a width "W1," a leading
end (not shown), a trailing end 50, and opposing side edges 52, 54. See FIGURE 5.
[0094] In general, the length of the substrate web element precursor 48 is not directly
related to the length of any one felt 26 to be made therefrom. Rather the length of
the precursor 48 is controlled by other factors, generally factors related to manufacturing
convenience and economy of scale.
[0095] For example, the length of the precursor 48 may be one which is convenient for collecting
and winding up as a roll 56. In FIGURE 5, only a portion of the length "L1" is illustrated,
the rest being wound up on roll 56. The quantity of the precursor material 48 should
be no more than the amount of the precursor material which the felt manufacturer contemplates
using economically in a given period of time. However, the quantity should be great
enough to allow the manufacturer to achieve economies of scale in the process of actually
weaving the precursor material, as related to the associated set-up time required
to set-up the weaving process for the specific weave pattern and material to be fabricated.
[0096] By using such factors of convenience and economy of scale in determining the length
of the substrate web element precursor 48, by weaving the precursor as a flat-woven
substrate, and by generally ignoring the length of any specific felt to be made with
the precursor material, significant manufacturing economies can be achieved over the
conventional practice of endless weaving each substrate 35 to a length directly related
to the finished length of a known felt to be made therefrom. In addition, by weaving
the substrate web element precursor 48 in a flat-weaving process, the precursor can
be made on a shuttle-less loom, whereby the generally higher weaving speed of the
shuttle-less loom can be achieved. Examples of shuttleless looms are those known as
projectile looms, rapier looms, and jet weaving looms.
[0097] As a general rule, in this invention, the roll 56 of precursor material 48 is fabricated
and stored prior to the time the felt manufacturer receives specifications for a felt
to be made therefrom. Rather, the manufacturer can make up a number of such rolls
56 ahead of time, having a variety of sets of properties related to e.g. weave pattern,
thread type, and the like. Thus, the felt manufacturer might stock e.g. six different
types of flat-woven substrate web precursor materials in roll form. The e.g. six different
sets of properties would typically represent the substrate webs most commonly used
to make felts according to the invention.
[0098] When an order is received for a felt, along with the corresponding specifications,
the felt manufacturer's first step in making the felt is to review the existing stock
of rolls 56 to see if a stock roll can be used to make the substrate web 36 or, if
more than one substrate web is needed in the substrate 35, if a stock roll can be
used to make at least one of the substrate webs 36. If so, the trailing end 50 of
the respective substrate web element precursor 48 is unrolled from the roll 56, as
shown in FIGURE 5. Appropriate length "L2" and width "W2" for making the substrate
web 36 are determined, and a substrate web element 42, with corresponding length and
width, opposing surfaces 61, 63, and side edges, is cut from the substrate web element
precursor 48. The extremities of "L2" and "W2" are shown as dotted lines on the woven
fabric in FIGURE 5. It will be appreciated that the length-to-width ratio of the substrate
web element illustrated in FIGURE 5 is smaller than the typical length-to-width ratio.
[0099] With "L2" and "W2," and the corresponding outline of the substrate web element 42,
established, the substrate web element 42 is cut from the substrate web element precursor
48, the remaining length of precursor material 48 is re-wound on roll 56, and the
roll put back into storage.
[0100] Referring now to FIGURES 7 and 8, a jointing table 58 includes a slot 60 extending
along, and inwardly of, one of its edges 62. First and second lower stabilizing strips
64 are secured to the top of the jointing table 58 along the opposing edges of the
slot 60. Each lower stabilizing strip 64 includes a relatively thin steel substrate
65, overlain with a sheet of sandpaper 67.
[0101] A conventional ultrasonic unit 75 is mounted for traversing slot 60, along the edge
62 of the table 58. By structural framework not shown, the ultrasonic unit 75 extends
downwardly through slot 60, such that ultrasonic horn 76, and corresponding rotary
ultrasonic anvil 78 are disposed at approximately the height of the top of table 58.
A preferred rotary anvil 78 has a thickness of about .013 inch (33 mm), an included
edge angle of 45 degrees to about 90 degrees, and a edge radius at the tip of .010
inch (.25 mm). FIGURE 6 illustrates a typical such ultrasonic unit, available from,
for example, Branson Company, Danbury, Connecticut as Series 900, Model 108, with
F-10 slitter assembly. The Branson unit is preferably operated at 20,000 Hertz, with
power up to 15 kilowatts. The frequency and power settings, as usual, depend On the
specifics of the rest of the operation, and so can be determined in the usual way
on an application by application basis.
[0102] The structural framework holding the ultrasonic unit is mounted for movement along
the edge 62 of the table parallel to slot 60, to thus carry the ultrasonic unit along
slot 60 the full width "W2" of the substrate web element 42 while maintaining the
horn 76 and anvil 78 at table top height.
[0103] With the ultrasonic unit withdrawn to its home position adjacent the edge 80 of the
table, and suspended in the slot 60, and with lower stabilizing strips 64 in place
as shown in FIGURES 7 and 8, the substrate web element 42 is placed on the jointing
table 58 with first and second underlying and overlying end portions 66, 68 respectively,
of the element 42, lying on and extending across slot 60, and with the respective
first and second ends 70, 72 disposed outwardly of the table 58 from the slot 60,
toward edge 62, and generally aligned with each other. In this position, second end
portion 68 is superposed over first end portion 66, and the end portions 66, 68 extend
away from the ends 70, 72 in a common direction. In this position, shown in FIGURE
7, the end portions 66, 68 of the substrate web element represent two thicknesses
of the substrate web element overlying the slot 60.
[0104] After the end portions 66, 68 have been positioned as shown in FIGURE 7, a second
pair of stabilizing strips 64 are placed on top of the end portions 66, 68, directly
above the stabilizing strips 64 which are on the top of the jointing table 58. The
second pair of stabilizing strips 64 are constructed the same as the first pair which
is placed on the top of table 58. However, the second pair of stabilizing strips 64
are placed with the sandpaper layer facing downwardly, whereby the sandpaper layers
on the upper and lower pairs of stabilizing strips 64 are facing each other, and are
in contact with the corresponding upper and lower surfaces of the end portions 66,
68.
[0105] The ultrasonic unit is then activated. As the ultrasonic unit is activated, the horn
76 begins oscillating against the rotary anvil 78 as shown by the double-headed arrow
in FIGURE 8. In addition, a force "F" is imposed urging the horn 76 down toward the
rotary anvil 78. Typical such force is about 20 pounds (9 kilograms). In addition,
downward force of e.g. about 10 to about 20 pounds (about 4 to about 9 kilograms)
is exerted on the second set of stabilizing strips 64 by a pair of pressure rollers
94 on opposing sides of the ultrasonic unit 75. See FIGURE 8. The rollers 94 are mounted
in common to the structural framework which mounts the ultrasonic unit 75 to the table
58. The rollers 94 thus move along edge 62 and slot 60 along with any movement of
the ultrasonic unit 75.
[0106] With the ultrasonic unit thus activated, and the substrate web element on the jointing
table as shown in FIGURE 7, the ultrasonic unit is moved along the slot 60, with the
rollers 94 exerting stabilizing downward pressure on the stabilizing strips 64 to
thereby stabilize end portions 66, 68 at a travelling locus adjacent the advancing
ultrasonic unit 75. The ultrasonic horn and anvil correspondingly act on the two thicknesses
of the substrate web element at a locus defined by the combination of the horn 76
and the anvil 78. The downward force on the rollers 94 urges the sandpaper layers
on stabilizing strips 64 into intimate contact with the end portions 66, 68, thus
stabilizing the end portions 66, 68 on the top of the table while the ultrasonic unit
75 is applying energy along the cut line 82 shown in FIGURE 7.
[0107] The action of the horn and anvil on the substrate web element generates an advancing
locus of localized application of ultrasonic energy to the substrate web element along
the cut line 82. See FIGURE 7. The localized application of energy by the ultrasonic
unit 75 creates thermal energy which severs the first and second ends 70, 72 from
the substrate web element 42 along the line 82, simultaneously forming a corresponding
new first end 84 and new second end 86. The ultrasonic unit 75 advances the full length
of the cut line 82, thus severing the first and second ends 70, 72 from the remainder
of the substrate web element at line 82, as surplus material. Once the ends 70, 72
have been completely severed, the ultrasonic unit is preferable retracted to its home
position at the edge 74 of table 58.
[0108] As the substrate web element 42 is cut along line 82, forming new first end 84 and
new second end 86, the localized application of energy also causes limited flow of
the fused thermoplastic material among the combination of the warp and weft threads
44, 46 at the advancing severing locus. As the fused thermoplastic material flows,
it creates bridges 88 of fused thermoplastic material between and among adjoining
ones of the threads 44, 46. The bridges 88 generally extend between and among adjoining
threads, including between threads of the upper end portion 68 and the lower end portion
66 as the force in the nip at the horn 76 and anvil 78 urges the end portions 66,
68 toward each other.
[0109] Accordingly, as part of the action of the ultrasonic unit 75, the end portions are
generally simultaneously urged toward each other by the ultrasonic unit 75, are severed,
and are fuse bonded to each other under the modest downward force applied at the ultrasonic
horn 76, along line 82. The fuse bonding of the end portions to each other along line
82 generally creates a joint 90 between the overlying end portion 68 and the underlying
end portion 66, and extending across the width of the substrate web element at an
angle of at least 45 degrees with an axis "X" extending along the length of the substrate
web element 42 (See FIGURE 12), whereby the substrate web element 42 is transformed
into a closed loop configuration, having opposing surfaces 91, 93, and side edges,
and is thereafter identified as a substrate web 36.
[0110] The fuse bonding preferred in the invention applies a limited amount of energy to
the cut line 82 to cut through the end portions 66, 68, and to concurrently fuse together
adjoining ones of the threads 44, 46 as the end portions 66, 68 are urged together.
The fusing of threads 44, 46 is so limited to the cut line 82 that voids normally
existing in the woven substrate web are generally maintained adjacent to the joint.
Further, the general weave pattern of the substrate web element 42 is maintained throughout
the joint 90, although the voids are somewhat smaller, and at the joint may be filled
in, because of the pressure applied while the fuse-bonding and subsequent rapid cooling
take place.
[0111] The amount of fused material is so limited that there is preferably no general flowing
of fused material to generally destroy the weave pattern, and fill all voids and surface
texture, at the new ends 84, 86. Rather, the typical joint 90 exhibits the typical
surface texture corresponding to the general weave pattern of the substrate web element
42. While the fuse-bonding process preferably does not completely destroy the weave
pattern and surface texture, voids 92 may be reduced in size or closed by the fused
thermoplastic material which flows during the fuse-bonding process.
[0112] The degree to which voids and surface texture are maintained is a function of, among
other factors, the amount of energy applied to the ultrasonic unit 75, the pressure
applied between the horn and the anvil, the mass of the material being cut at line
82, and the speed of advance of the ultrasonic unit along the line 82. For a typical
substrate web element, the Branson ultrasonic unit disclosed above may be advanced
at a speed of about 0.5 foot to about 10 feet (about 15 cm to about 305 cm) per minute.
A range of about 1 foot to about 2 feet (about 30 cm to about 61 cm) per minute is
preferred.
[0113] FIGURES 8 and 9 illustrate the creation of bridges 88 to effect the fuse-bonding
which creates the joint 90. From an edge view of the joint being formed, FIGURE 8
illustrates in general the relative locations of the components of the substrate web
element 42 being cut and fuse bonded, along with the general positioning of the horn
and anvil. A wide gap is shown between the horn and anvil in order to be able to illustrate
the threads that are, of course, actually forced together in the nip 96 as the severing
locus advances along the cut line 82. FIGURE 9 shows a front view of the joint, taken
at 9-9 of FIGURE 8, thus illustrating exemplary bridging structure between and among
the adjacent threads 44, 46, and the corresponding discontinuities across the voids
where thermoplastic material did not flow enough to fill the voids in the process
of making the joint. The fused material, of course, was subsequently cooled to the
solid state after the joint was formed. A further type of discontinuity can occur
in the joint wherein a gap 95 may exist across the width of the joint, whereby, at
a given point in the width of the substrate web, no fused material connects adjacent
threads along the width of the joint. See FIGURE 9. The amount of space occupied by
voids 92 is exaggerated in FIGURE 9 in order that the voids 92 be readily discernible.
Further, the number and spacing of bridges in any particular joint, and the actual
pattern of bridges at the joint, depend on the conditions used in the fuse-bonding
process of making the joint.
[0114] While not absolutely critical to the invention, it is preferred that voids 92 be
present in the joint, and that the surface texture and weave pattern at and adjacent
to the joint reflect the overall weave pattern of the resulting substrate web 36.
[0115] A general fusing together of all the thermoplastic material along the line 82 where
the joint is created is not desired, and in the preferred embodiments, is not acceptable.
However, where the ends 70, 72 are properly aligned with each other, the invention
contemplates forming the joint 90 by application of fuse-bonding energy to the ends
70, 72 to form the fuse bonded joint at ends 70, 72 without a corresponding severing
of the substrate web element 42. In such situation, cut line 82 is irrelevant, and
no cut is formed there.
[0116] As the joint is formed by the ultrasonic unit 75, the end portions 66, 68 are in
facing relationship with each other, and the joint 90 so formed joins the end portions
66, 68 about a 360 degree directional change in the material as the material traverses
the joint. After the ultrasonic unit has been withdrawn to its home position, the
end portions 66, 68 overlie each other, with joint 90 therebetween, as seen in dashed
outline in FIGURE 10.
[0117] With the joint so formed, the substrate web is configured as a closed loop, with
the formation of the joint being the last step in closing the loop. As the so-formed
closed loop substrate web 36 is further processed as a closed loop web, the end portions
66, 68 are inherently rotated generally about the joint 90 to an orientation where
the end portions extend away from each other at generally 180 degrees, as shown in
solid outline in FIGURE 10, in the process of participating in normal loop-type dispositions
of the substrate web. Upon such rotation of the end portions 66, 68, the joint 90
tends to maintain the 360 degree configuration at and immediately adjacent the joint,
as seen in solid lines in FIGURE 10, thus forming a crown 100 on a first surface 102
of the substrate web 36, and a corresponding valley 104 on the opposing second surface
106.
[0118] Crown 100 extends from the general plane of first surface 102 by an amount which
would leave a lasting impression on any paper web processed with a felt having such
a crown. However, applicants have surprisingly discovered that the prominence of the
crown 100, and corresponding prominence of valley 104, are greatly attenuated during
normal needling of batts 98 of fibrous material, securing the batts to and into the
substrate web 36, whereby the crown is substantially flattened during the needling
process. In such process, the substrate web 36 is held under tension of e.g. about
3 to about 35 pounds per linear inch (about 3.5 to about 40 kilograms per linear centimeter)
across the width of the substrate web. FIGURE 11 schematically depicts the reduction
in prominence of the crown 100 and valley 104 as a result of the needling process.
A comparison of the depictions of the crown 100 and valley 104 in FIGURES 10 and 11
illustrates the degree of reduction in prominence of the crown and valley.
EXAMPLE
[0119] A papermaking felt of the invention was made as follows. A substrate web element
precursor 42 was woven in a Broken Twill pattern. The machine direction count was
14 threads per inch (5.5 threads per cm). The machine direction (warp) thread was
a 6 ply thread. First 2 singles were plied at 10 turns per inch (4 turns per cm) in
the "Z" direction, then 3 of such yarns were plied together at 6 turns per inch (2.4
turns per cm) in the "S" direction. The cross machine (weft) thread was a single monofilament
at 8 threads per inch (3.1 threads per cm). The substrate web element precursor so
woven was .037 inch (.94 mm) thick, and basis weight was 1 ounce per square foot (.0305
gram per square cm).
[0120] Two substrate web elements were cut from the substrate web element precursor so made.
Each substrate web element was fuse bonded as discussed above, to make joints 90,
crowns 100, and valleys 104, thus making closed loop substrate webs 36A and 36B using
the above Branson ultrasonic unit, powered with 15 kilowatts at 20,000 Hertz, advanced
along the cut line 82 at a speed of 1 foot (30 cm) per minute. Each substrate web
36 had a tensile strength, along its length, of 30 pounds per linear inch (5.4 kilograms
per cm) across the width at joint 90, and a general tensile strength, along its length
and away from the joint 90, of 275 pounds per linear inch (49 kilograms per cm).
[0121] With the edge portions 66, 68 held away from each other with modest tension as shown
in FIGURE 10, each crown 100 had a height "HR" of about 4 millimeters. Each valley
104 had a height of "HV" of about 2 millimeters.
[0122] The substrate webs were combined in surface-to-surface relationship as shown in FIGURE
14, with the crowns 100 facing inwardly in the loop. The closed loop configuration
of the two substrate webs, comprising the substrate 35, was then consolidated by needling
2 ounces of nylon fibrous batt material (20 denier threads) into the substrate. Needling
was done on a Fehrer Needle Loom, using 2000 needle penetrations per square inch (310
penetrations per square cm), with 8 barb Foster needles.
[0123] After needling, the joints were practically impossible to find. The so-needled felt
had machine direction tensile strength at the joint of 620 pounds per linear inch
width (111 kilograms per linear cm), and machine direction tensile strength outside
the joint area of about 1000 pounds per linear inch width (179 kilograms per linear
cm).
[0124] After the needling operation, the combination of substrate web 36 and batts 98 is
herein referred to as a felt, although those skilled in the art recognize that various
conventional processing steps remain to be performed before the product is ready for
shipment and installation on the paper machine. Once the needling step is completed,
a felt made with the fuse-bonded joint 90 of the invention is processed like any conventional
felt through the remainder of the normal steps of the felt manufacturing process.
[0125] In felts made according to the process steps described above with respect to forming
the joint 90, and needling the resulting substrate web 36, the joint is virtually
impossible to detect, either visually or by inspection of paper made with the felt.
According to a preferred embodiment illustrated in FIGURE 13, the felt 26 is oriented
in the press section such that the crown 100 is displaced from the surface 28 which
carries the web of paper 22 being formed. In the embodiment illustrated in FIGURE
13, the crown is both (i) displaced from the web of paper 22, by being disposed on
the surface of the substrate web 36 which is away from the web 22, and (ii) directed
away from the web 22. Accordingly, the crown makes no mark on the web 22 which can
be detected by unaided visual observation such as by a microscope or the like. Applicants
contemplate that the needling process helps create holes through the substrate web
at and adjacent joint 90 to add permeability of the felt to air and water at and adjacent
the joint.
[0126] General tensile strength of the substrate web 36, generally distributed along the
length of the substrate web 36, is greater than the tensile strength at joint 90.
Typically the general tensile strength is at least 50% greater than the tensile strength
at the joint, and may be twice or three times as great. After completion of the needling
and other normal finishing process steps, the resulting felt has a tensile strength
generally acceptable for papermaking felt applications. Surprisingly, the lesser tensile
strength of the substrate web 36 at joint 90 of the substrate web 36 does not preclude
achieving satisfactory tensile strength in the felt as a finished product. Typically
the tensile strength at the joint 90 is at least 75% as great as the general tensile
strength of the felt at loci remote from the joint.
[0127] FIGURES 12 and 14-16 illustrate additional applications of the joint 90 to various
substrate web configurations. With respect to FIGURES 12 and 14-16, the discussion
which follows assumes that felts made with the substrate webs illustrated therein
are mounted with the inside of the loop of the web shown being directed toward the
inside of the press loop in the press section.
[0128] FIGURE 12 shows a substrate 35 including a single substrate web 36 wherein the substrate
web includes first and second joints 90A and 90B, each extending transverse to the
length of the substrate web, across the entire width of the substrate web, the joints
being spaced from each other along the length of the substrate web - e.g. preferably
by at least 25% of the length of the substrate web. The crowns 100 are both displaced
from the web of paper 22 and directed away from the web.
[0129] The substrate web 36 of FIGURE 12 is formed into e.g. a closed-loop configuration
by first forming the first joint 90A by joining the first end of the first substrate
web element 42A to the second end of the second substrate web element 42B to form
joint 90A and by subsequently forming the second joint 90B by joining first end of
the second substrate web element 42B to the second end of the substrate web element
42A to form the second joint 90B. Additional substrate web elements 42C, 42D, etc.
may be incorporated into the closed loop configuration, with additional corresponding
joints, by joining the first end of each substrate web element to the second end of
the succeeding substrate web element and forming a corresponding joint.
[0130] FIGURE 14 illustrates a substrate 35 incorporating first and second inner and outer
substrate webs 36A and 36B, respectively. Both webs 36 incorporate crowns 100A and
100B and corresponding valleys 104A, 104B, both of which are displaced from, and directed
away from, the web 22.
[0131] FIGURE 15 illustrates a substrate 35 incorporating third and fourth inner and outer
substrate webs 36C and 36D, respectively. Inner web 36C incorporates a crown 100C
which is directed toward the paper web, but is displaced from the paper web by outer
substrate web 36D. Outer web 36D incorporates a crown 100D which is both displaced
from, and directed away from, the paper web 22.
[0132] FIGURE 16 illustrates a substrate 35 incorporating fifth and sixth inner and outer
substrate webs 36E and 36F, respectively. Inner web 36E incorporates a crown 100E
which is displaced from the paper web 22 by outer substrate web 36F. Outer web 36F
is a web which has been fabricated with a closed loop weaving process, and accordingly
has no joint.
[0133] The substrate 35 can incorporate any number of substrate webs 36. Any or all of such
substrate webs can incorporate therein one or more joints 90. In general, it is preferred
that the crown 100 be oriented away from the paper web 22. However, in some cases,
the crown 90 can be directed toward the paper web 22 as seen in FIGURE 15, and in
some cases, may be displaced from the paper web by only the fibers needled into the
substrate 35. In general, tensile strength of a second or third, etc. substrate web
36, incorporating a second etc., joint 90 corresponds with the tensile strength considerations
given above.
[0134] It is contemplated that the operation and functions of the invention have become
fully apparent from the foregoing description of elements, but for completeness of
disclosure the usage of the invention will be briefly described.
[0135] Those skilled in the art will now see that certain modifications can be made to the
apparatus and methods herein disclosed with respect to the illustrated embodiments,
without departing from the spirit of the instant invention. And while the invention
has been described above with respect to the preferred embodiments, it will be understood
that the invention is adapted to numerous rearrangements, modifications, and alterations,
and all such arrangements, modifications, and alterations are intended to be within
the scope of the appended claims.
1. A substrate web (35/36) for use in making a papermaking felt (26), said substrate
web circumscribing a closed loop path and having a length along the closed loop path,
and a width transverse to the length, said substrate web generally defining first
and second opposing surfaces (102,106) along the length thereof, and comprising:
(a) woven threads (44,46) extending along the length and the width of said substrate
web (35), and defining a weave pattern, the threads e.g. being selected from nylon,
polyester and polyurethane; and
(b) a joint (90) extending in a direction transverse to the length of said substrate
web (35/36), e.g. extending across substantially the entirety of the width of the
web, said joint comprising fused elements of ones of said woven threads (44,46), fused
to each other at locations spaced along the width of said substrate web.
2. A substrate web as in claim 1, said joint (90) comprising a crown (100) on said first
surface (102) and a corresponding valley (104) on said second surface (106).
3. A substrate web as in claim 1 or claim 2, said joint (90) having an outer surface,
and texture in said outer surface, along the width of said substrate web (35/36),
corresponding with the weave pattern.
4. A substrate web as in any one of claims 1 to 3, said joint (90) having a first tensile
strength along the direction of the length of said substrate web (35/36), said substrate
web having a second general tensile strength along the length thereof, said second
general tensile strength being at least 50% greater than said first tensile strength.
5. A substrate web as in any one of claims 1 to 4, said woven threads (44,46) comprising
a first set of threads (44) extending along the length of the substrate web and a
second set of threads (46) extending along the width of the substrate web, said joint
(90) comprising fused ends of ones of said threads in said first set.
6. A substrate web as in any one of claims 1 to 5, said joint (90) comprising fused ends
of ones of said woven threads extending along the length of said substrate web (35/36),
fused to each other at locations spaced from each other along the width of said substrate
web, and irregularities in said outer surface, along the width of said substrate web,
corresponding with the weave pattern.
7. A papermaking felt (26) made with a substrate web of any one of claims 1 to 6.
8. A papermaking felt (26) circumscribing a closed loop path, said papermaking felt having
a first length along the closed loop path and a first width transverse to the first
length, a first surface (28) for contacting and carrying a web of paper being formed
with said papermaking felt, and a second opposing surface (34), said papermaking felt
comprising:
(a) a substrate web (35/36), having third and fourth opposing surfaces (102,106),
a second length and a second width, said substrate web having woven threads (44,46)
extending along the second length and the second width of said papermaking felt, thus
defining a weave pattern, and a joint extending (90) transverse to the second length,
said joint (90) comprising fused elements of ones of said woven threads (44,46), fused
to each other along the second width; the threads for example being selected from
nylon, polyester and polyurethane; and
(b) first and second batts (38,40) of fibrous material assembled in said papermaking
felt on said first and second opposing surfaces (32,34).
9. A papermaking felt as in claim 8, said joint (90) comprising a crown (100) on said
third surface (102) and a corresponding valley (104) on said fourth surface (106).
10. A papermaking felt as in claim 8 or claim 9, said substrate web (35/36) comprising
a first substrate web (36B, D), said joint comprising a first joint (90A), and including
a second substrate web (36A, C) having fifth and sixth opposing surfaces, a third
length and a third width, second woven threads extending along the third length and
the third width, and a second joint (90B) extending transverse to the third length,
said second joint (90B) exhibiting a third tensile strength along the third length,
said second substrate web (36A, C) having a fourth general tensile strength generally
distributed along the third length at loci displaced from said second joint, said
fourth tensile strength being greater than said third tensile strength, said first
and second substrate webs (36B, D; 36A, D) being disposed in face-to-face relationship
with each other over substantially the entirety of ones of the surfaces of the respective
substrate webs, said first and second joints (90A, 90B) being spaced from each other,
and preferably said first and second joints are spaced from each other by at least
25% of the first length.
11. A papermaking felt as in any one of claims 8 to 10, said substrate web (35/36) comprising
a first substrate web (36E) including said joint, and including a second endless woven
substrate web (36F) having fifth and sixth opposing surfaces, said first and second
substrate webs being disposed in face-to-face relationship with each other over substantially
the entirety of ones of the surfaces of the respective first and second substrate
webs (36E, F).
12. A papermaking felt as in any one of claims 8 to 11, each respective joint (90) comprising
ends of ones of said woven threads (44,46) fused to each other at locations spaced
along the width of the respective substrate web (36), each joint having an outer surface,
and texture in the outer surface, along the width of the substrate web, corresponding
with the weave pattern.
13. A papermaking felt as in either of claims 10 and 11, said first substrate web (36B,
D) being disposed at said first surface (28), said first substrate web (36B, D) being
oriented such that said crown (100B, 100D) is directed away from said first surface.
14. A papermaking felt as in any one of claims 8 to 10, said joint comprising a first
joint (90A), said substrate web comprising a first substrate web (36A), and including
a second substrate web (36B) having fifth and sixth opposing surfaces, a third length
and a third width, said second substrate web having second woven threads (44,46) extending
along the third length and the third width of said substrate web, and a second joint
(90B) extending transverse to the third length, said second joint comprising fused
elements of ones of said second woven threads (44,46), fused to each other along the
third width, said second joint (90B) comprising a second crown (100B) on said fifth
surface and a corresponding second valley (104B) on said sixth surface, and for example
said second crown (100B) is directed away from said first surface (28).
15. A papermaking felt as in any one of claims 8 to 14, the or each said joint (90) extending
along the entirety of the closed loop path, and across substantially the entirety
of the second width of said substrate web (36).
16. A papermaking felt as in any one of claims 8 to 15, said papermaking felt (26) being
adapted to process sustantially any type of paper web without leaving on the paper
web any mark, detectable by unaided visual observation, indicating the presence of
either of said first and second joints.
17. A method of making a papermaking felt (26) circumscribing a closed loop path, the
papermaking felt comprising a substrate web (35), the papermaking felt having opposing
first and second surfaces (28,34), and first and second batts (38,40) of fibrous material
assembled to the first and second surfaces, the papermaking felt (26) having a first
length along the closed loop path and a first width extending transverse to the length,
the substrate web (35) having opposing third and fourth surfaces (102,106), and first
and second edges, the method comprising the steps of:
(a) fabricating a substrate web element (36), the substrate web element having a second
length, a second width transverse to the second length, first and second end portions
(66,68), and first and second ends (70,72);
(b) forming the substrate web element (36) to create a closed loop and thereby from
the substrate web element into the substrate web, by forming, in the substrate web
element, a fuse bonded joint (90) extending across the substrate web element (36),
and correspondingly across the substrate web (35), e.g. across substantially the entirety
of the width thereof, between the first and second edges in a direction transverse
to the length; and
(c) securing a batt (38 or 40) of fibrous material to at least one of the third and
fourth surfaces.
18. A method as in claim 17, the fabricating of step (a) comprising fabricating a flat-weave
substrate web precursor (48), the flat-weave substrate web precursor (48) having a
length, a width transverse to the length of the substrate web precursor, and a weave
pattern; and severing the substrate web element (42) from the flat-weave substrate
web precursor, the forming of the substrate web element (42) into a closed loop in
step (c) comprising joining the first and second ends (70,72) and forming the fuse-bonded
joint (90) at or adjacent the first and second ends.
19. A method as in claim 17, the fabricating of step (a) comprising fabricating a substrate
web precursor (48), having a length, a width transverse to the length of the substrate
web precursor, and fifth and sixth opposing surfaces, by weaving threads extending
along the length and width of the substrate web precursor, and severing, from the
substrate web precursor (48), the substrate web element (42); the forming of step
(b) comprising superposing the first and second end portions (66,68) of the substrate
web element, with the first and second ends (70,72) generally aligned with each other
and the first and second end portions (66,68) extending away from the respective first
and second ends in a common direction, and fuse bonding the first and second end portions
to each other at the first and second ends, to form the fuse-bonded joint (90) at
the first and second ends (70,72) while the first and second end portions (66,68)
are so superposed with respect to each other, thus forming the substrate web element
into the closed loop substrate web having a fuse-bonded joint extending across the
substrate web.
20. A method as in any one of claims 17 to 19, the forming of step (b) comprising superposing
first and second end portions (66,68) of the substrate web element (42) adjacent the
first and second ends (70,72), with the first and second end portions extending away
from the respective first and second ends in a common direction; severing the substrate
web element (42) across the second width proximate the first and second ends (70,72),
thus forming a new first end and a new second end (84,86), while the first and second
end portions (66,68) are superposed with respect to each other, whereby the respective
first and second end portions extend away from the new first end (84) and the new
second end (86) in the common direction; fuse bonding the new first end and the new
second end to each other to form the fuse-bonded joint (90) while the first and second
end portions are so superposed with respect to each other, thus forming the substrate
web element (42) into the closed loop substrate web (36) having the fuse-bonded joint
extending across the second width; and rotating the first and second end portions
(66,68) about the fuse-bonded joint (90) such that the first and second end portions
generally extend away from each other, with the fuse-bonded joint forming a crown
(100) on the third surface and a valley (104) on the fourth surface.
21. A method as in either of claims 17 and 18, the method comprising severing first and
second substrate web elements (42) from at least one flat weave substrate web precursor,
each such substrate web element having first and second ends (70,72), forming the
substrate web into a closed loop path by joining the first end of the first substrate
web element to the second end of the second substrate web element, to form a first
joint, by joining the first end of the second substrate web element to the second
end of the next substrate web element to form a second joint, and by so joining the
first end of each substrate web element to the second end of the succeeding substrate
web element, and forming a corresponding joint, with the first end of the last substrate
web element being joined to the second end of the first substrate web element.
22. A method as in any one of claims 17 to 21, the method comprising joining the first
and second ends (70,72), to form the joint (90) by fuse bonding members of the substrate
web element (42) to each other at locations spaced along the second width of the substrate
web element, the joint (90) having an outer surface, and texture in the outer surface
of the joint, along the second width of the substrate web, corresponding with any
weave pattern.
23. A method as in any one of claims 17 to 22, each joint (90) describing an angle of
at least 45 degrees with an axis extending parallel to the second length.
24. A method as in claim 20, the method including reducing the prominence of the crown
(100) such that paper made with the papermaking felt carries no mark, detectable by
unaided visual observation, indicating the presence of the joint.
25. A method as in claim 24, the method including needling a batt (38,40) of fibrous material
to at least one of the third and fourth surfaces subsequent to rotating the first
and second end portions (66,68) about the fuse-bonded joint (90).
26. A method as in any one of claims 17 to 25, including concurrently severing and fuse
bonding the substrate web element (42) at the first and second end portions (66,68),
e.g. by applying ultrasonic energy to the first and second end portions at a corresponding
severing locus, and preferably by applying ultrasonic energy to the substrate web
element by advancing the severing locus across the third width.
27. A method as in any one of claims 17 to 26, including limiting forming of a respective
fuse bonded joint (90) to a single application of fuse bonding energy across the width
of the substrate web element.
28. A method as in any one of claims 17 to 27, including the step, performed as part of
step (b), of cutting the substrate web element (42) across the second width proximate
the first and second ends, thus forming a new first end (84) and a new second end
(86) adjacent the respective first and second ends (70,72), and thereby making a new
cut in the substrate web element (42) in each of the first and second end portions
(66,68) concurrent with fuse bonding the end portions to each other at the new first
end and the new second end.
29. A method as in any one of claims 17 to 28, the method including applying ultrasonic
energy to the substrate web element by advancing an ultrasonic device across the second
width.
30. A method as in any one of claims 17 to 29, the step (a) of fabricating a substrate
web element (42) comprising (i) fabricating first and second flat-woven substrate
web precursors (48) having first and second sets of properties, differing from each
other, the first substrate web precursor having a third length, and a third width
transverse to the third length, and a first weave pattern, the second substrate web
precursor having a fourth length, and a fourth width transverse to the fourth length,
and a second weave pattern; (ii) subsequent to fabricating the first and second flat-woven
substrate web precursors (48), specifying properties of the papermaking felt to be
made; (iii) selecting, according to the properties specified in step (ii), a preferred
one of the first and second flat-woven substrate web precursors (48), for making the
papermaking felt; and (iv) severing the substrate web element (42) from the selected
one of the first and second flat-woven substrate web precursors (48) to appropriate
second length and second width according to the properties specified in step (ii),
the substrate web element (42) so severed having the first and second edges extending
along the second length, and the corresponding first and second ends extending across
the second width, and fifth and sixth opposing surfaces.
31. A method as in any one of claims 17 to 30, the fabricating of the substrate web element
(42) of step (a) including (i) fabricating a flat-weave substrate web precursor (48)
on a shuttleless loom, the flat-weave substrate web precursor having a third length,
and a third width transverse to the third length, (ii) severing, from the flat-weave
substrate web precursor (48), the substrate web element (42) having the second length,
and the second width transverse to the second length.
32. A papermaking felt made according to the method of any of claims 17 to 31.
33. A method of making paper on a continuous-process paper machine (10), the paper machine
including a forming fabric (24) circumscribing a first closed loop path and a papermaking
felt (26) circumscribing a second closed loop path, the papermaking felt (26) having
a first surface (28) for receiving thereon a web of paper (22) being formed on the
paper machine (10), and an opposing second surface remote from the first surface,
the method comprising employing, as the continuous loop felt (26), a felt having a
first length, a first width, and comprising a substrate web (35) and first and second
batts (38,40) of fibrous material assembled to opposing third and fourth surfaces
of the substrate web, the third and fourth surfaces of the substrate web (35) generally
corresponding to the first and second surfaces of the felt (26), the substrate web
comprising at least one substrate web element (36) having fifth and sixth opposing
surfaces and extending about the second closed loop path, the at least one substrate
web element (36) comprising a joint (90) extending across the first width, the joint
having a crown (100) on the fifth surface and a corresponding valley (104) on the
sixth surface, the method including orienting the papermaking felt (26) with respect
to the paper machine (10) such that the crown (100) is displaced from the first surface,
and preferably orienting the papermaking felt (26) with respect to the paper machine
(10) such that the fifth surface, and thus the crown (100), is directed away from
the first surface.