TECHNICAL FIELD AND PRIOR ART
[0001] The invention relates to a device for forming a leno weave in a weaving machine,
and to a weaving machine comprising such a device. The invention further relates to
a method for manufacturing such a device.
[0002] The term leno weave describes a weave in which leno threads, also referred to as
leno binding threads or leno warp threads, are twisted around weft threads.
[0003] US3698441 shows a device for forming a leno selvage, comprising at least two thread guides
mounted to an endless support element guided along an elongated endless path for guiding
a corresponding number of leno threads from a leno thread supply to a fixed binding
point.
SUMMARY OF THE INVENTION
[0004] It is the object of the invention to provide a device for forming a leno weave comprising
an endless support element with a long lifetime and at least one pair of thread guides
securely mounted thereto.
[0005] According to a first aspect of the invention, a device for forming a leno weave,
comprising an endless support element guided along an elongated endless path and a
thread guide mounted to the endless support element, in particular a pair of thread
guides distributed along the endless support element, is provided, wherein the endless
support element is supported by a pulley, wherein the thread guide is adapted for
guiding a leno thread towards a fabric, wherein the thread guide is provided with
a first segment for mounting the thread guide to the endless support element, which
first segment extends at an inner side of the endless support element, wherein the
pulley is provided with a notch, and wherein the endless support element and the pulley
are adapted to each other such that upon a circulation of the endless support element,
the first segment is received in a notch of the pulley.
[0006] Throughout this application and the claims the indefinite article "a" or "an" means
"one or more". Reference to "a first element" does not mandate presence of "a second
element". Further, the expressions "first" and "second" are only used to distinguish
one element from another element and not to indicate any order of the elements.
[0007] In a preferred embodiment, the thread guide is provided with a clamp having the first
segment extending at an inner side of the endless support element and a second segment
extending at an outer side of the endless support element.
[0008] In the context of the application, a clamp is defined as an element having two segments,
between which the endless support element is inserted. Using a clamp allows for a
secure fixing of the thread guides to the endless support element, as the thread guides
have a large contact surface with the endless support element. Thereby a damage of
the endless support element during mounting of the thread guide and during use can
be avoided. When using a clamp, a segment of the clamp extends along an inner side
of the endless support element, which inner side is contacting the pulley. According
to the application, upon each circulation of the endless support element, this segment
is received in the notch or in one of a plurality of notches for ensuring a smooth
guidance of the endless support element with the thread guide along the pulley.
[0009] In one embodiment, two or more pulleys having parallel axes of rotation are provided,
wherein in particular each pulley is provided with one or more notches.
[0010] In one embodiment, one pair of thread guides for forming a leno weave is provided,
wherein in particular in one embodiment the thread guides are evenly distributed along
the endless support element. In other embodiments, two pairs of thread guides are
provided, wherein in particular in one embodiment all thread guides are evenly distributed
along the endless support element.
[0011] In one embodiment, the endless support element inserted between the two segments
of the clamp forces the segments apart against internal restoring forces, so that
the endless support element is held between the two segments of the clamp by the restoring
forces. In alternative or in addition, in one embodiment, the clamp is fixed to the
endless support element using a fixation wire having a base and two bendable legs
or using a U-shaped fixation element having two legs, each leg having screw thread
for cooperating with a nut. The segments of the clamp and the endless support element
in one embodiment are provided with through holes for receiving the two legs. In embodiments,
the fixation wire or the U-shaped fixation element is inserted from an inner side
of the endless support element such that the base is arranged at the inner side of
the endless support element and the legs are inserted in the through holes of the
clamp and the endless support element, wherein for securing the clamps, at an outer
side of the endless support element the bendable legs are bent, in particular bent
towards each other and towards the endless support element, or the legs having screw
thread are secured by using nuts. The base of the fixation wire or the fixation element
protrudes from the inner side of the endless support element, wherein in particular
a height and a width of the protruding segment of the clamp together with the base
are smaller than a depth and a width of the notch or the notches of the pulley.
[0012] In one embodiment, the pulley is provided with only one notch, wherein the first
segment of the thread guide or, in case two or more thread guides are provided, the
first segment of each thread guide is received in said notch upon circulation of the
endless support element. In other embodiments, the pulley is provided with more than
one notch. In this case, in one embodiment the first segment of the thread guide or,
in case two or more thread guides are provided, the first segment of each thread guide
is received in an associated notch of the plurality of notches upon circulation of
the endless support element.
[0013] In one embodiment, the pulley is provided with a pulley disc, wherein the pulley
disc has an opening adapted for receiving the thread guide, in particular for receiving
one thread guide or both thread guides of the pair of thread guides, upon circulation
of the endless support element, wherein the opening is aligned in the circumferential
direction of the pulley with the notch. In case the pulley is provided with more than
one notch, the opening is aligned with the notch receiving the first segment of the
thread guide. In other words, in this case the opening is aligned with one notch of
a plurality of notches. In embodiments, the number of openings is minimized to avoid
a weakening and an irregular outer contour of the pulley disc. In embodiments, two
or more thread guides are provided. In case the first segments of all thread guides
are received in one common notch, the pulley disc can be provided with only one opening,
which is aligned in the circumferential direction of the pulley with said notch. In
case the first segments of different thread guides are received in different notches,
the pulley disc is provided with a corresponding number of openings, each opening
being aligned in the circumferential direction of the pulley with one of said notches.
In one embodiment, two pulley discs are provided at either end of the pulley, each
pulley disc being provided with an opening. In other embodiments, only one pulley
disc is provided. In case several pulleys are provided, in one embodiment all pulleys
are provided with pulley discs. In other embodiments, only one pulley, in particular
a driving pulley is provided with a pulley disc.
[0014] In one embodiment, the endless support element is a toothed belt having a series
of evenly distributed teeth, in which series of teeth one tooth is missing, wherein
the thread guide is mounted to the toothed belt in position of the missing tooth.
In one embodiment, two teeth are missing in the series of teeth, wherein two thread
guides are mounted to the toothed belt in positions of the two missing teeth. The
toothed belt in one embodiment is manufactured with missing teeth. In other embodiments,
teeth of the toothed belt are removed and the thread guides are mounted, in particular
clamped, to the toothed belt in replacement of the removed teeth. Toothed belts have
no slippage, when correctly tensioned. This allows for a reliable synchronization
of the movement of the thread guides with a main drive of weaving machine.
[0015] In one embodiment, the teeth are rounded and in particular have a semi-circular shape.
The rounded, in particular semi-circular shape enables the teeth to mesh and de-mesh
smoothly with the pulley, and, thus allows a high speed movement of the toothed belt.
The teeth can also have another rounded or curved shape.
[0016] The pulley in one embodiment is provided with a number of evenly distributed notches,
wherein the number of teeth including the missing tooth of the toothed belt is an
integer multiple of the number of notches of the driving pulley, in particular an
odd integer multiple of the number of notches. In case the number of teeth is an integer
multiple of the number of notches, upon each circulation of the toothed belt, each
thread guide is received in one associated notch. In case the number of teeth including
the missing tooth is an even integer multiple of the number of notches of the pulley,
all thread guides of a pair of evenly distributed thread guides are received in the
same notch. In case the number of teeth including the missing tooth is an odd integer
multiple of the number of notches of the pulley, wherein for example the odd integer
multiple equals three, the thread guides of one pair of evenly distributed thread
guides are received in the two notches displaced by 180°. In one embodiment, all notches
are identical in design. In other embodiments, the pulleys are each provided with
a first notch adapted for receiving the first segment of the thread guide or the teeth
of the toothed belt, and a number of second notches, which second notches are only
adapted for receiving the teeth of the toothed belt, wherein the number of teeth including
the missing tooth is an integer multiple of the entirety of first notches and second
notches.
[0017] The thread guide is provided with a thread eye to which in use a leno thread is threaded
for guiding the leno thread coming from a thread supply towards a fabric, in particular
towards a beat-up line of the fabric and/or an edge of the fabric, for example an
edge at a side of the fabric. In embodiments, the thread guide is provided with a
thread eye having a wear-resistant surface. In one embodiment, the thread guide is
made of wear-resistant material and/or is provided with a wear-resistant coating in
the region of the thread eye. In another embodiment, a hollow insert made of a wear-resistant
ceramic material is mounted to the thread guide and serves as the thread eye.
[0018] In one embodiment, the thread guide is L-shaped having a first end provided with
the thread eye and a second end provided with the first segment, wherein the first
end and the second end are arranged at an angle to one another, wherein in particular
an angle between the first end and the second end is larger than 90°. By arranging
the first end and the second end at an angle to one another which is larger than 90°,
a distance of the thread eye from the endless support element is increased.
[0019] In one embodiment, at least one thread detector is provided for detecting the absence
and/or presence of a thread to be guided by the thread guides. The at least one thread
detector in one embodiment is a contactless thread detector, in particular an optical
detector, using a transmitter sending a signal and a receiver receiving the signal,
wherein a presence of a leno thread causes an interruption of the signal. In alternative
or in addition, a thread detector comprising a piezoelectric element is provided.
In one embodiment, the piezoelectric element is mounted to a distal end of a rotation
shaft of the pulley, wherein by means of the piezoelectric element it is possible
to detect whether a leno thread guided by the thread eye of the thread guide passes
along the piezoelectric element. In an alternative embodiment, a piezoelectric element
is provided near the thread eye of the thread guide, wherein a detected signal is
transmitted wirelessly to a control unit.
[0020] In one embodiment, the pulley is a driving pulley, which is drivingly coupled to
a motor, in particular an electric motor, wherein the motor is synchronized to the
weaving machine. For example, the motor can move in any direction and synchronized
to the weaving machine. In addition, the device comprises at least one second pulley,
i.e. a driven pulley, wherein rotation axes of the pulleys are arranged in parallel.
The second pulley in one embodiment is identical in design to the first pulley. In
other embodiments, the second pulley differs in design, for example has a smaller
or larger diameter and a resulting different number of notches, wherein the first
segment of the thread guide is received in different notches each time the thread
guide passes the driven pulley. In one embodiment, a tubular motor is provided, which
is directly coupled to the driving pulley. In other embodiments, the driving pulley
is coupled to the motor via a shaft, which shaft in one embodiment is housed in a
shaft housing.
[0021] In one embodiment, a sensor is provided fixed in position, which sensor is adapted
to giving a signal each time the thread guide passes the sensor. The sensor in one
embodiment is a Hall sensor, and the thread guide is at least partly made of a magnetizable
material, in particular made of steel. In an alternative embodiment, the sensor is
a proximity switch that generates a signal when the thread guide comes close to the
proximity switch. The sensor in one embodiment is used for a synchronization of the
movement of the thread guide to a weaving machine, wherein for example the sensor
signal is transmitted to a control unit, which controls the motor coupled to the driving
pulley.
[0022] In one embodiment, a pair of thread guides is mounted to the endless support element,
wherein the thread guides of the pair of thread guides are distributed, in particular
evenly distributed along the endless support element. In embodiments of the invention,
all thread guides of the device are provided with a clamp and mounted to the endless
support element using said clamp.
[0023] According to a second aspect, a weaving machine comprising a device for forming a
leno weave as described above is provided. In one embodiment, at least two devices
for forming a leno weave are provided, which are arranged at opposite sides of a fabric
for forming a selvedge.
[0024] According to a third aspect, a method for manufacturing a device for forming a leno
weave is provided, the device comprising an endless support element and a thread guide
mounted to the endless support element, wherein the thread guide is fixed to the endless
support element by a clamp having two segments, such that the two segments of the
clamp of the thread guide extend at opposing sides of the endless support element.
The endless support element in embodiments of the invention is a toothed belt, wherein
a tooth of the toothed belt is removed and the thread guide is fixed to the endless
support element in the position of the removed tooth.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] In the following, an embodiment of the invention will be described in detail with
reference to the drawings. Throughout the drawings, the same elements will be denoted
by the same reference numerals. In the schematic drawings
- Fig. 1
- shows in a perspective view a first embodiment of a device for forming a leno weave
in a weaving machine.
- Fig. 2
- is a perspective view of a detail of Fig. 1 in an enlarged scale.
- Fig. 3
- shows an endless support element of the device of Fig. 1 together with thread guides
mounted thereto in a perspective view.
- Fig. 4
- shows the endless support element of Fig. 3 in a front view.
- Fig. 5
- is a detail V of Fig. 4 in an enlarged scale.
- Fig. 6
- is a top view of a thread guide mounted to the endless support element of Fig. 3,
- Fig. 7
- is a sectional view of the thread guide mounted to the endless support element of
Fig. 6.
- Fig. 8
- is a perspective view of a lower part of the device of Fig. 1 showing a driving pulley.
- Fig. 9
- is a sectional view showing a driven pulley and a sensor of a second embodiment of
a device similar to Fig. 1.
- Fig. 10
- shows in a perspective view a third embodiment of a device for forming a leno weave
in a weaving machine.
DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION
[0026] Fig. 1 shows a device 1 according to the invention in which two leno threads 2, 3
are raised and lowered alternately to form a leno weave by twisting the leno threads
2, 3 around each other for binding a weft thread 4 into the leno threads 2, 3. The
device 1 is to be arranged on a weaving machine, for example a rapier weaving machine,
an air jet weaving machine or any other kind of weaving machine, wherein only a reed
5 of the weaving machine is schematically shown in Fig. 1. Fig. 2 is a perspective
view of a detail of Fig. 1 in enlarged scale.
[0027] The device 1 in one embodiment is arranged in the region of outer edges of a fabric
8, for example on the outer edge at the weft insertion side of the fabric or at the
outer edge at the opposite side of the fabric, or in a central region of the weaving
machine for producing leno weaves between two fabrics. In one embodiment, two or more
devices 1 are arranged side by side on an outer edge of the fabric.
[0028] For moving the leno threads 2, 3, the device 1 comprises an endless support element
6 and a pair of thread guides 7 mounted evenly distributed to the endless support
element 6, wherein each thread guide 7 is adapted for guiding a leno thread 2, 3 between
a thread supply (not shown) and a fabric 8.
[0029] The device further comprises a driving pulley 9 and a driven pulley 10 having parallel
axes 94, 104, wherein the driving pulley 9 and the driven pulley 10 are conjointly
referred to as pulleys 9, 10. When mounted to the weaving machine, in the embodiment
shown, the axes 94, 104 of the pulleys 9, 10 are arranged in parallel to a pulling
direction of the warp threads and the leno threads indicated by an arrow in Fig.1,
which pulling direction is also referred to as warp thread direction or leno thread
direction.
[0030] The endless support element 6 is supported by the two pulleys 9, 10 and the thread
guides 7 are guided along an elongated endless path, thereby twisting the leno threads
2, 3 guided by the thread guides 7 around each other for binding a weft thread 4 into
the leno threads 2, 3.
[0031] In one embodiment, the thread supply for the leno threads 2, 3 comprises fixedly
arranged bobbins (not shown), wherein the endless support element 6 is driven to move
a number of turns in one direction, and then driven to move a number of turns in the
reverse direction in order to avoid twisting the leno threads 2, 3 too much in the
area opposite the fabric, i.e. a back area of the weaving machine.
[0032] In another embodiment, the thread supply for the leno threads 2, 3 comprises rotatably
arranged bobbins (not shown), for example as known from
US3698441, wherein the endless support element 6 can be driven to move in one direction only.
[0033] The driving pulley 9, which in the embodiment shown is the lower pulley, is driven
by an electric motor 11, which electric motor 11 is controlled separately of a main
drive of the weaving machine (not shown) and of a drive of the shedding device (not
shown). The electric motor 11 in one embodiment is a stepper motor, which is electrically
controlled and can be driven in both directions of rotation. In one embodiment, the
stepper motor is controlled in an open loop. In alternative or in addition to the
open loop control, a signal of a position sensor 17 (see Fig. 9 and described in more
detail below) can be used for a feed-back control of the position of the stepper motor.
A synchronization of the device 1 and the weaving machine in one embodiment is set
and controlled according to a program, so that the leno threads 2, 3 move and cross
each other at an expected moment of time within the weaving cycle. In the embodiment,
the driving pulley 9 is the lower pulley. The driving pulley 9 is connected to the
electric motor 11 using a shaft 24 (see Fig. 8) which is housed in a shaft housing
12.
[0034] The shaft housing 12 further functions as a support for a housing 13 of the pulleys
9, 10. In the embodiment shown, on the housing 13 of the pulleys 9, 10 two fixed guiding
elements 14 are mounted, each guiding element 14 comprising a bended wire. In an alternative
embodiment, the two guiding elements are formed integrally. The leno threads 2, 3
are threaded through an opening in the housing 13 and guided via the guiding elements
14 to the thread guides 7. By means of the guiding elements 14 it is avoided that
the leno threads 2, 3 coming from the thread supplies contact the endless support
element 6 and/or the pulleys 9, 10, in particular when a thread guide 7 is in the
upper position or the lower position. In one embodiment, additional guiding elements
(not shown), such as rounded wires, are provided near the opening in the housing 13
through which the leno threads 2, 3 are threaded, to avoid that the leno threads 2,
3 come into contact with the opening in the housing 13 and could be damaged by the
housing 13.
[0035] The housing 13 is further provided with a fitting 15 for a connection with an air
supply (not shown), wherein the fitting 15 is connected to a blower 18, which is adapted
to blow away dust that will accumulate near one of the pulleys 9, 10. In Fig. 2, two
such blowers 18 are shown. In an alternative embodiment, two blowers distributed in
the vertical direction are provided, one near the driven pulley 10, which in the embodiment
shown is the upper pulley, and one near the driving pulley 9, which in the embodiment
shown is the lower pulley. In other embodiments, only one blower is provided.
[0036] On a front side of the housing 13, as best seen in Fig. 2, two at least essentially
vertical bars 19 are provided in order to prevent that an operator will be caught
by the moving endless support element 6 and/or by the thread guides 7.
[0037] The endless support element 6 in the embodiment shown is an endless toothed belt,
and the pulleys 9, 10 are provided with a number of evenly distributed notches 90,
100 adapted for accommodating the teeth 60 of the toothed belt.
[0038] Fig. 3 to 8 show the endless support element 6 together with the thread guides 7
mounted thereto in a perspective view, a front view, in an enlarged scale, in a top
view and in a sectional view, respectively.
[0039] As best seen in Figs. 3, 6 and 7, the thread guides 7 are each provided with a first
end having a thread eye 70 and a second end having a clamp 71 for clamping the thread
guide 7 to the endless support element 6. The clamps 71 each have a first segment
72 and a second segment 73, wherein the endless support element 6 is inserted between
the first segment 72 and the second segment 73. When clamping the thread guide 7 to
the endless support element 6, the clamp 71 at least contacts an inner side of the
endless support element 6 with the first segment 72 and an outer side of the endless
support element 6 with the second segment 73. Hence, the clamp 71 has a large contact
surface with the endless support element 6, so that the endless support element 6
is not damaged by the clamp 71, during the fixation and as well as and even more important
during operation of the device 1.
[0040] In the embodiment shown, the clamps 71 are each fixed to the endless support element
6 using a fixation wire 16 having a base 160 and two bendable legs 161. As shown in
Fig. 7, the two segments 72, 73 of the clamp 71 and the endless support element 6
are for example each provided with two through holes 74, 64 for receiving the two
legs 161 of the fixation wire 16. The fixation wire 16 is inserted from an inner side
of the endless support element 6 such that the base 160 is arranged at the inner side
of the endless support element 6 and the legs 161 are inserted in the through holes
74, 64 of the clamp 71 and the endless support element 6. After the insertion, distal
ends of the legs 161 are bent towards each other and towards the endless support element
6.
[0041] The thread eye 70 protrudes from a front face of the endless support element 6. The
thread guides 7 each are L-shaped having a first end provided with the thread eye
70 and a second end provided with the clamp 71, which are arranged at an angle with
respect to each other, which angle is preferably larger than 90°, for example an angle
between 100° and 110°, thereby increasing a distance of the thread eye 70 from the
endless support element 6.
[0042] In the embodiment shown, a hollow insert 75 (see Fig. 7) made for example of a wear-resistant
ceramic material is mounted to the thread guide 7 and serves as the thread eye 70.
The hollow insert 75 is provided with funnel-shaped entry and exit regions for a smooth
guidance of the leno threads 2, 3.
[0043] In the embodiment shown, the endless support element 6 is a toothed belt having a
series of evenly distributed teeth 60, in which series of teeth 60 two teeth are missing.
The two thread guides 7 are mounted to the endless support element 6 in positions
of the missing teeth.
[0044] As shown in Fig. 5, the first segment 72 of the clamp 71 arranged at an inner side
of the endless support element 6 and first segment 72 and the base 160 of the fixation
wire 16 protrude from the inner side of the endless support element 6. In the embodiment
shown, an overall height and an overall width of the first segment 72 and the base
160 are smaller than a height and a width of the teeth 60, allowing that the first
segment 72 and the base 160 can be received by a notch 90, 100 of the pulleys 9, 10
(see Figs. 1 and 2) upon circulation of the endless support element 6 while avoiding
that the first segment 72 and the base 160 contact the notch 90, 100. This is advantageous
for reducing wear.
[0045] In the embodiment shown, the number of teeth 60 including the missing teeth of the
endless support element 6 is an odd integer multiple of the number of notches 90 of
the driving pulley 9. Therefore, upon circulation of the endless support element 6,
the first segments 72 of the clamps 71 of the two evenly distributed thread guides
7 are each received in one associated notch 90 of the driving pulley 9, wherein the
two associated notches are displaced by 180°. In the embodiment shown, as best seen
in Fig. 4, the toothed belt has a series for forty-two teeth, of which forty teeth
are present and two teeth are missing, wherein the thread guides 7 are mounted in
the positions of the missing teeth. In this exemplary embodiment, the pulleys 9 and
10 each have fourteen notches, so that the ratio of teeth/notches equals three. In
this embodiment, always several teeth 60 of the endless support element 6 are engaging
with notches 90 of the driving pulley 9, so that slippage is avoided and a reliable
synchronization with a weaving machine can always be obtained. The number of teeth
and notches is only by way of example. The toothed belt can also have a series with
another number of teeth, preferably an even number of teeth, for example forty eight
teeth, thus forty six teeth and two missing teeth. In this case, for a ratio of three,
the pulleys 9, 10 each have sixteen notches.
[0046] An odd integer multiple, for example a ratio of teeth/notches that equals to three,
offers the advantage that a sufficient shedding between the leno threads 2, 3 can
be obtained, and that the revolution speed of the drive motor 11 remains rather low.
In a typical use, the endless support element 6 is moved over half a revolution during
each weaving cycle, so that in the example with a ratio of three, during each weaving
cycle, the drive motor 11 will rotate 1,5 revolutions. Due to this, the revolution
speed of the drive motor 11 allows to start, to stop or to reverse the direction of
rotation of the drive motor 11 easily.
[0047] An even integer multiple, for example a ratio of teeth/notches that equals to four,
can offer the advantage that the drive motor 11 can be controlled more easily. In
this example, the drive motor 11 rotates two revolutions each weaving cycle, such
that after each weaving cycle the drive motor 11 comes in the same position again,
what allows a more easily control of the drive motor 11, in particular when the motor
11 is controlled in two different directions of rotation.
[0048] Fig. 8 is a perspective view of a lower part of the device 1 of Fig. 1 showing a
driving pulley 9 together with an endless support element 6 and a thread guide 7 fixed
thereto. As shown in Fig. 8, the driving pulley 9 in the embodiment shown is provided
with two pulley discs 91, 92. As explained above, in the embodiment shown, upon each
circulation, the first segment 72 of the clamp 71 of each thread guide 7 is received
in one associated notch 90. In case of the above ratio that equals three, then during
each following circulation of the endless support element 6 each thread guide 7 will
be received by one of two notches that are displaced by 180°. In order to avoid an
interference of the thread guides 7 with the pulley discs 91, 92, the pulley discs
91, 92 are provided with two openings 93, which openings 93 are aligned in circumferential
direction with the associated notches 90. As shown in Fig. 1 and 2, the driven pulley
10 in the embodiment shown is not provided with any pulley discs. In an alternative
embodiment, the driven pulley 10 is also provided with pulley discs, wherein the pulley
discs are also provided with openings for avoiding an interference with the thread
guides 7.
[0049] In the embodiment shown in Fig. 8, a leno thread detector 20 is provided, for example
a piezoelectric element, which is mounted between the hollow insert 75 and a segment
76 of the thread guide 7. By means of the piezoelectric element 20 it can be detected
whether a leno thread 3 that is present in and guided by the thread eye 70 of the
thread guide 7, because such a leno thread 3 causes vibrations on the piezoelectric
element 20. Such a detected signal can be transmitted wirelessly to a control unit.
In other embodiments, other thread detectors are provided, for example a thread detector
having droppers as used in a warp stop motion. In an alternative embodiment, for example
to this end use is made of a piezoelectric element that can make contact with a leno
thread when passing along the piezoelectric element and that is mounted to a distal
end of the shaft 24 driven by the motor 11, which shaft 24 functions as the rotation
shaft of the pulley 9. In an alternative embodiment, a thread detector can be arranged
near the thread supply, in particular near a thread bobbin in order to detect if leno
thread are taken off from the bobbin.
[0050] Fig. 9 is a sectional view of an upper part of a second embodiment of a device 1
for forming a leno weave in a weaving machine, which is similar to the device of Fig.
1. For the same or similar elements, reference is made to the description above. Fig.
9 shows the driven pulley 10 and a sensor 17, which sensor 17 is adapted for giving
a signal each time a thread guide 7 passes the sensor 17. The sensor 17 is mounted
fixed in position to the housing 13 of the device 1, wherein in the embodiment shown,
the sensor 17 is mounted to detect the absence or presence of the thread guide 7 in
the uppermost position. The sensor 17 is for example a Hall sensor, which can be small
and is suitable to detect a thread guide 7 or a portion of the thread guide 7 made
of metal that passes along the sensor 17. In one embodiment, the signal of the sensor
17 is used for providing a position information to a control unit (not shown) used
for controlling the electric motor 11 (see Fig. 1) driving the endless support element
6 in synchronization with the weaving machine.
[0051] As shown in Fig. 9, in the embodiment, the driven pulley 10 is mounted via bearings
23 on a shaft 22, so as to be rotatable about this shaft 22, wherein the shaft 22
is arranged fixed in position in the housing 13. In other embodiments, the shaft 22
is mounted rotatably in the housing 13 and the pulley 10 is secured to the shaft 22.
The shaft 24 can be mounted in the housing 13 in a way similar as the shaft 22.
[0052] Fig. 10 shows in a perspective view a third embodiment of a device 1 for forming
a leno weave in a weaving machine, which is similar to the device of Fig. 1. For the
same or similar elements, reference is made to the description above. In contrast
to the embodiment shown in Fig. 1, two sensor devices are provided, namely a sensor
17, for example a Hall sensor, which is adapted to giving a signal each time a thread
guide 7 passes the sensor 17, and a thread detector 21 for detecting the absence and/or
presence of a leno thread 2, 3. In the embodiment shown, the thread detector 21 is
a contactless thread detector comprising a transmitter 210 and a receiver 212, which
are attached to the two vertical bars 19 respectively. In use, the transmitter 210
is sending a signal and the receiver 212 is receiving the signal, wherein a presence
of a leno thread 2, 3 between the transmitter 210 and the receiver 212 causes a measurable
interruption of the signal. The thread detector 21 allows to monitor whether a leno
thread 2, 3 passes the thread detector 21 when the thread guides 7 are moved by the
endless support element 6. The sensor 17 and the thread detector 21 can be used conjointly
to verify whether a leno thread 2, 3 is present and interrupts the signal of the thread
detector 21 just before the thread guide 7 reaches its uppermost position, which position
is detected by the sensor 17 and/or to verify whether a leno thread 2, 3 is present
and interrupts the signal of the thread detector 21 just after the thread guide 7
has left its uppermost position, which position was detected by the sensor 17.
[0053] In the embodiment shown, the driving pulley 9 and the driven pulley 10 have the same
size and the same number of notches 90, 100. In an alternative embodiment (not shown),
the lower pulley can have a larger diameter and a larger number of notches than the
upper pulley. This allows that the leno threads will cross each other closer to the
lower pulley than the upper pulley. In case the upper pulley is the driven pulley,
the number of notches of the upper pulley can be chosen independent of the number
of teeth of the toothed belt, wherein a correct timing is ensured by the driving pulley.
In the embodiments of Figs. 1 to 10, the endless support element 6 is supported by
two pulleys 9, 10. In alternative embodiments, the endless support element can be
supported by more than two pulleys, for example three pulleys of which one is a driving
pulley and the other ones are driven pulleys.
[0054] In the embodiments of Figs. 1 to 10, two thread guides 7 evenly distributed along
the endless support element 6 are shown. In an alternative embodiment, a number of
pairs of threads guides 7 can be provided, which are preferably evenly distributed
along the circumference of the endless support element 6. In another alternative embodiment
three thread guides can be arranged along the endless support element, wherein during
each weaving cycle the drive motor 11 is controlled, such that a shedding between
the leno threads 2, 3 can be obtained with one leno thread in the upper position,
while the two other leno threads are in the lower position, or with one leno thread
is in the lower position, while the two other leno threads are in the upper position.
In still another alternative, four thread guides can be arranged evenly distributed
along the endless support element, or two pairs of thread guides can be arranged next
to one another and evenly distributed along the endless support element can be provided.
1. Device for forming a leno weave, comprising an endless support element (6) guided
along an elongated endless path and a thread guide (7) mounted to the endless support
element (6), wherein the endless support element (6) is supported by a pulley (9,
10), and wherein the thread guide (7) is adapted for guiding a leno thread towards
a fabric (8), characterized in that the thread guide (7) is provided with a first segment (72) for mounting the thread
guide (7) to the endless support element (6), which first segment (72) extends at
an inner side of the endless support element (6), and the pulley (9, 10) is provided
with a notch (90, 100), wherein the endless support element (6) and the pulley (9,
10) are adapted to each other such that upon a circulation of the endless support
element (6), the first segment (72) is received in the notch (90, 100) of the pulley
(9, 10).
2. Device for forming a leno weave according to claim 1, characterized in that the thread guide (7) is provided with a clamp (71) having the first segment (72)
extending at an inner side of the endless support element (6) and a second segment
(73) extending at an outer side of the endless support element (6).
3. Device for forming a leno weave according to claim 2, characterized in that the clamp (71) is fixed to the endless support element (6) by using a fixation wire
(16) having a base (160) and two bendable legs (161) or using a U-shaped fixation
element having two legs, each leg having screw thread for cooperating with a nut.
4. Device for forming a leno weave according to claim 1, 2 or 3, characterized in that the pulley (9) is provided with a pulley disc (91, 92), wherein the pulley disc (91,
92) has an opening (93) adapted for receiving the thread guide (7) upon circulation
of the endless support element (6), wherein the opening (93) is aligned in the circumferential
direction of the pulley (9) with the notch (90, 100).
5. Device for forming a leno weave according to any one of claims 1 to 4, characterized in that the endless support element (6) is a toothed belt having a series of evenly distributed
teeth, in which series of teeth one tooth is missing, wherein the thread guide (7)
is mounted to the toothed belt in position of the missing tooth, wherein in particular
the teeth (60) are rounded and in particular have a semi-circular shape.
6. Device for forming a leno weave according to claim 5, characterized in that the pulley (9, 10) is provided with a number of evenly distributed notches (90, 100),
wherein the number of teeth (60) including the missing tooth of the toothed belt is
an integer multiple of the number of notches (90, 100) of the pulley (9, 10), in particular
an odd integer multiple of the number of notches (90, 100).
7. Device for forming a leno weave according to any one of claims 1 to 6, characterized in that the thread guide (7) is provided with a thread eye (70) having a wear-resistant surface,
wherein in particular a hollow insert (75) made of a wear-resistant ceramic material
is mounted to the thread guide (7) and serves as the thread eye (70).
8. Device for forming a leno weave according to claim 7, characterized in that the thread guide (7) is L-shaped having a first end provided with the thread eye
(70) and a second end provided with the first segment (72), wherein the first end
and the second end are arranged at an angle to one another, wherein in particular
the angle between the first end and the second end is larger than 90°.
9. Device for forming a leno weave according to any one of claims 1 to 8, characterized in that at least one thread detector (20, 21) is provided for detecting the absence and/or
presence of a leno thread (2, 3) to be guided by the thread guides (7).
10. Device for forming a leno weave according to any one of claims 1 to 9, characterized in that the pulley (9) is a driving pulley, which is drivingly coupled to a motor, in particular
an electric motor (11), wherein the motor is synchronized to the weaving machine.
11. Device for forming a leno weave according to any one of claims 1 to 10, characterized in that a sensor (17) is provided fixed in position, which sensor (17) is adapted to giving
a signal each time the thread guide (7) passes the sensor (17).
12. Device for forming a leno weave according to claim 11, characterized in that the sensor (17) is a proximity switch or a Hall sensor, and preferably the thread
guide (7) is at least partly made of a magnetizable material, in particular made of
steel.
13. Device for forming a leno weave according to any one of claims 1 to 12, characterized in that a pair of thread guides (7) is mounted to the endless support element (6), wherein
the thread guides (7) of the pair of thread guides are distributed along the endless
support element (6).
14. Weaving machine comprising a device (1) for forming a leno weave according to any
one of claims 1 to 12.
15. Method for manufacturing a device (1) for forming a leno weave, the device (1) comprising
an endless support element (6) and a thread guide (7) mounted to the endless support
element (6), characterized in that the thread guide (7) is fixed to the endless support element (6) by a clamp having
two segments (72, 73), such that the two segments (72, 73) of the clamp (71) of the
thread guide (7) extend at opposing sides of the endless support element (6).