[0001] This invention relates generally to a method of knitting a double-knit fabric and
a circular knitting machine for carrying out this method wherein the vertical length
of travel of the cylinder needles is reduced by lowering the stitch forming ledge
of the sinkers as the needles are being raised to clearing level and raising the stitch
forming ledge of the sinkers as the needles are being drawn downwardly to stitch drawing
level, and more particularly, to such a method and machine wherein the sinkers are
supported for inward and outward movement between the dial and cylinder needles along
a downwardly inclined path of travel and with the sinkers being moved outwardly and
upwardly as the needles are drawn downwardly to raise the level of the stitch drawing
ledge during stitch loop formation and with the sinkers being moved inwardly and downwardly
as the needles are raised so that the shed stitch loops are moved inwardly and downwardly
by the nebs of the sinkers.
[0002] During movement of the cylinder and dial needles in a conventional double-knit circular
knitting machine, a newly formed loop slides downward on the needle stem and provides
the various pattern structures desired. When forming a pattern structured fabric,
such as a rib knit structure, any yarn breakage during knitting typically results
in the knit fabric dropping from the machine. When dropping occurs, the yarn from
the cup end of the dropped fabric must be threaded onto at least every two or three
needles and then restored to its initial state before dropping. This mandates an operator's
slowly running the knitting machine to assure proper threading.
[0003] In Japanese patent publication SHO 63-42186, a double-knit circular knitting machine
is disclosed which solves some of the aforementioned problems by the application and
use of a novel sinker. However, as disclosed in this Japanese publication, the distance
between the foremost end of the sinker and the rotating dial is shortened when the
sinker advances to the inner side of the machine. As a result, a thick fabric cannot
be knitted unless the dial is upwardly moved for increasing the separation distance
so as to allow a knitted fabric to easily pass through the formed gap without interference.
Because the sinker is arranged perpendicularly to the knitting needle, the sidewall
of the sinker rest ring is small, thus creating an unstable sinker movement.
[0004] With the foregoing in mind, it is an object of the present invention to provide a
method of knitting a double-knit fabric on a circular knitting machine which overcomes
the aforementioned deficiencies of the prior art.
[0005] It is still another object of this invention to provide a double-knit circular knitting
machine used for practicing the aforementioned method which overcomes the deficiencies
of the prior art.
[0006] In accordance with the present invention, a double-knit circular knitting machine
includes a plurality of cylinder needles supported in a rotating needle cylinder for
vertical movement parallel to the axis of rotation of the needle cylinder. Dial needles
are radially slidable on a sinker dial and are operative with the cylinder needles.
Sinkers are supported for inward and outward movement between the cylinder needles.
Each sinker includes a stitch drawing ledge and a neb on the inner end portion of
each of the sinkers. The sinkers cooperate with adjacent needles in the formation
of knit stitch loops. The outer end portions of the sinkers are supported on a rotatable
ring located exteriorly of the needle cylinder for movement in a radial direction
and along a downwardly inclined path of travel between the needles. The inner end
portions of the sinkers are supported on a sinker nose ring for movement along the
downwardly inclined path of travel.
[0007] Yarn is fed to the needles when the cylinder needles are in a raised, clearing position
and when the dial needles are in an outward advanced position. The cylinder needles
are successively moved downwardly while the dial needles are successively moved inwardly.
The sinkers are simultaneously moved in an outwardly and upwardly direction along
the downwardly inclined path of travel while the cylinder needles are being lowered
and the dial needles are being retracted so that the stitch drawing ledge engages
the yarn. The stitch drawing ledge cooperates with the associated adjacent needles
to form stitch loops of a length determined by the amount of upward vertical movement
imparted to the stitch forming ledge and the amount of downward and inward movement
of the cylinder and dial needles.
[0008] The cylinder needles are successively moved upwardly and the dial needles are successively
moved outwardly after forming the stitch loops therewith. The sinkers are simultaneously
moved in an inwardly and downwardly direction along the downwardly inclined path of
travel to engage sinker nebs with the fabric and move the same inwardly and downwardly
to aid in shedding the stitch loops from the cylinder and dial needles as they are
respectively raised and advanced with the newly formed stitch loop thereon.
[0009] In order that the present invention may be more readily understood, reference will
now be made to the accompanying drawings, in which:-
Figure 1 is a vertical sectional view through the needle cylinder of the knitting
machine and illustrating the manner in which the sinkers are mounted for radial sliding
movement along a downwardly inclined path of travel relative to the needles;
Figure 2 is a side elevational view of one of the special type of sinkers utilized
in the present invention;
Figure 3 is a somewhat schematic developed elevational view showing the paths of travel
of the needles and associated sinkers at one yarn feeding position;
Figures 4 through 10 are side elevations of the upper portions of the cylinder and
dial needles and associated sinkers showing their relationship during the successive
steps of forming stitch loops and then shedding the previously formed stitch loops
from the dial and cylinder needles, and being taken along their respective section
lines 4-4 through 10-10 of Figure 3; and
Figure 11 is a side elevational view of a second embodiment of the special type of
sinker used in the present invention.
[0010] As shown in Figure 1, a rotating needle cylinder
1 is supported on a driven ring gear
6 and the outside surface of the needle cylinder
1 is provided with the usual needle slots
1a in which cylinder needles, broadly indicated at
2, are supported for vertical movement parallel to the axis of rotation of the needle
cylinder
1. As illustrated, hooked latch needles are preferred. Each knitting needle
2 is provided with a hook
2a and a pivoted latch
2b (Figure 4), and an operating butt, as indicated at
2c (Figure 1). Conventional knitting cams, including stitch cam means supported on cam
plates
9, are provided for imparting vertical movement to the knitting needles
2. The cam plates
9 are supported on the inner surface of the cam holder ring
8 which is fixed on a cam ring plate
10.
[0011] A rotating dial
4 is supported on a needle dial hub
7. The outer surface of the dial
4 is spaced from and extends over an upper portion
1b of the rotating needle cylinder and is rotatable therewith. The top surface of the
dial
4 is provided with the usual needle slots in which hooked latch dial needles, broadly
indicated at
3, are supported for radial movement in conjunction with cylinder needles
2 during knitting operation. Each dial needle
3 is provided with a needle hook
3a and latch
3b (Figure 4), and an operating butt
3c (Figure 1). Knitting cams, including stitch cam means supported on sinker cam plate
12, are provided for imparting radial, horizontal movement to the knitting needles
3. The dial cam plate
12 is supported on the lower surface of a dial cam holder ring
11 which is fixed to a dial cam ring plate
13.
[0012] The upper surface of the needle cylinder includes the downwardly and inwardly inclined
surface
1b which defines a sinker nose support ring for the nose of the sinkers as will be described
herein. A sinker support bed
14 is fixed to the exterior of the upper end of the needle cylinder
1 and is provided with a downwardly and inwardly inclined sinker sliding surface
14a defined by the lower ends of sinker slots formed in the sinker bed
14 and at the same downwardly inclined angle as the sinker sliding surface
1b of the sinker nose ring defined on the upper surface of the needle cylinder
1. The inclined surface
1b and the sliding surface
14a collectively define sinker support ring means of inverted truncated conical shape.
As illustrated, the sinker sliding surface
14a is located at a lower level than the sinker sliding surface
1b.
[0013] Special types of sinkers, broadly indicated at
15, cooperate with the cylinder and dial needles
2,
3 to form stitch loops and are supported for movement in a radial direction and along
a downwardly and inwardly inclined path of travel between the cylinder needles
2. Inward and outward radial sliding movement of the sinkers
15, along the downwardly and inwardly inclined path of travel, is controlled by sinker
cams
17 supported in a fixed position on a sinker cap
16. Sinker cap
16 is in turn supported on a sinker cap ring
18 which is supported in spaced-apart locations on the upper ends of support standards
19 surrounding the needle cylinder
1. As will be noted, the sinker cams
17 are supported in a downwardly inclined position at the same downwardly inclined angle
as the inclined sliding surfaces
1b and
14a on the respective inclined cylinder surface and sinker bed
14. The sinker sliding surfaces
1b and
14a are illustrated in Figure 1 as being downwardly and inwardly inclined at an angle
of around 20° relative to a line perpendicular to the vertically disposed cylinder
needles
2. While this 20° downwardly inclined angle is preferred, the present invention is
not limited to this particular angular inclination, but may be positioned at an angle
from 10° to 45°, and preferably within the range of 15° to 30°.
[0014] As best shown in Figure 2, the outer portion of the special sinker
15 includes an elongate body portion having an outer lower planar sliding edge
15e adapted to rest upon and slide along the inclined surface
14a of the sinker bed
14. The sinker
15 also includes an inner lower planar sliding edge
15b adapted to rest on and be slidably supported along the inclined sliding surface
1b on the upper surface of the cylinder
1. The inner sliding edge
15b is disposed at a higher level than the outer sliding edge
15e, as clearly shown in Figure 2. A stitch drawing ledge
15a is provided on the upper inner portion of the sinker and a neb
15d extends over the outer portion of the stitch drawing ledge
15a and defines a sinker throat
15c between the neb
15d and the outer portion of the stitch drawing ledge
15a. An upstanding operating butt
15f is provided on the outer and upper end portion of the elongated body portion of the
sinker
15. The butt
15f extends upwardly at a right angle from the body portion of the sinker
15 and is adapted to be engaged by the sinker cams
17 to impart the required inward and outward radial movement to the sinkers
15.
[0015] In conventional sinkers, the stitch drawing ledge extends along a line which is parallel
with the lower planar sliding edge of the sinker. In contrast to this conventional
construction, the present special type sinker is characterized by the stitch drawing
ledge
15a being slanted downwardly toward the operating butt
15f on the outer end portion of the elongate body portion of sinker
15. The downwardly inclined or outwardly slanting stitch drawing ledge
15a of the sinker
15 of the present invention is different from the normal type sinker in which the stitch
drawing ledge extends parallel to the lower planar sliding edge of the sinker. The
present sinker is also different from the special sinkers of the type disclosed in
U.S. patent numbers 3,837,185 and 3,986,371 wherein the stitch drawing ledge slants
downwardly or inwardly in the direction of the inner end of the sinker.
[0016] In Figure 3, the solid line
50 indicates the path of travel of the top of the hook of the cylinder needles
2 during a knitting cycle while the dash-dot line
52 indicates the path of travel of the stitch drawing ledge
15a during a knitting cycle. The dotted line
51 indicates the path of travel of the dial needle
3. The alternate long and double-dashed line
53 indicates the path of travel of the sinker throat
15c. A yarn feed carrier and finger
20 (Figures 1 and 8) is positioned to feed a yarn indicated at
54 (Figure 8) to the needles as they are moved to a stitch forming level.
[0017] In the method according to the invention, the needles
2,3 are successively raised as they approach the knitting station and are moved outwardly
to the clearing level along the solid line
50 in Figure 3 to a position where the previously formed loops surrounding the shanks
of the cylinder and dial needles
2,3 are positioned beyond the tip of the latches
2b, 3b, as shown in Figures 4-6. At the same time, the sinkers
15 are moved and retained in an inwardly and downwardly inclined position along the
downwardly inclined path of travel between the needles
2,3 so that the fabric is moved inwardly by the neb
15d to maintain the previously formed stitch loops below the tip of the latches
2b, 3b and in tight engagement with the shanks of the needles, as shown in Figure 6. The
inward and downward movement of the sinker
15 lowers the position of the stitch drawing ledge
15a below the normal horizontal path of travel, as indicated by the dash-dot line
52 in Figure 3, so that the cylinder needles
2 do not have to be raised as high to reach clearing level as would be the case if
the sinkers
15 were maintained at a higher level.
[0018] While the cylinder needles
2 are in a raised latch clearing position, and the dial needles
3 are in a most outwardly advanced position, yarn feed finger
20 feeds the yarn
54 to the hooks of the needles
2, 3. The cylinder needles 2 are lowered and dial needles
3 are retracted while the sinkers
15 begin to move outwardly and upwardly along the downwardly inclined path of travel,
as illustrated in Figure 7. With further downward vertical movement of the cylinder
needles
2 and further retraction of the dial needles
3, as indicated in Figure 8, the previously formed stitch loops close the latches
3a, 3b and the sinker
15 continues to move outwardly and upwardly so that the yarn in the cylinder needle
hook
2a will be drawn downwardly over the stitch drawing ledge
15a while the stitch drawing ledge
15a remains in the highest level, as illustrated in Figure 9.
[0019] While the yarn is being drawn down over the stitch drawing ledge
15a, both the outer and inner portions of the sinkers
15 are being supported. As shown in Figures 4-10, the lower planar sliding edge
15b on the inner end or nose of the sinker
15 is slidably supported on the downwardly and inwardly inclined surface
1b of the cylinder
1. Lower planar sliding edge
15e on the outer end portion of the sinker
15 is slidably supported
14a of the sinker bed
14 (Figure 1). Thus, both the inner and outer portions of the sinkers
15 are supported as the needles are drawn down to stitch forming level.
[0020] As shown in Figure 10, the cylinder needle
2 begins to rise at the point where the dial needle
3 is retracted to the innermost position. At this time, the sinker moves in the inwardly
and downwardly direction so that the previously formed stitch loops shed from the
upper end of the needle hook
2a is engaged by the neb
15d and moved inwardly to aid in shedding the stitch loop from the needle. The sinker
throat
15c pushes the knit fabric and assists the loop on the dial needle
3 to cast-off the stitch. This inward and downward movement of the sinkers
15 ensures that the needles
2 do not again pass upwardly through the shed stitch loop. The cylinder needle
2 continues to rise and the dial needle
3 begins its advance. This begins the start of the knitting cycle as illustrated in
Figure 4.
[0021] The inward and downward movement of the sinkers
15 ensures that the needles
2 do not again pass upwardly through the shed stitch loop. The sinkers
15 continue to move the fabric inwardly and downwardly as the needle
2 continues to rise, as shown in Figures 4 and 10, so that the newly formed stitch
loop is maintained in engagement with the outer surface of the needle shank and imparts
an opening motion to the latches of the needles. This knitting cycle is repeated at
each of the subsequent knitting stations around the needle cylinder to form the knit
fabric.
[0022] Alternatively, a compound or sliding latch needle with a modified cam also can be
used in accordance with the present invention. A jacquard apparatus for patterning
which can include a pattern wheel, a pattern drug, or other electronic patterning
device also can be included for knitting various artistic patterns.
[0023] The shape of the sinker is not limited. For example, Figure 11 illustrates a second
embodiment of the special type of sinker used in accordance with the present invention.
The sinker grooves in the machine can be modified as needed. The forward end of the
sinker
150 includes a stitch drawing ledge
150a extending horizontally. Inclined surface
150b is in a plane defined by the inclined surface
150e so that the entire lower edge of the sinker defined by both surfaces
150b, 150e are guided by sinker grooves. Sinker
150 includes a throat
150c and a neb
150d. A control butt
150f is included.
[0024] The use of sinkers
15 in accordance with the present invention offers several benefits. If a knit fabric
drops on account of yarn breakage during knitting, the machine can be threaded in
a similar manner as a single-knit circular knitting machine. Additionally, a thick
fabric can be knitted. The inwardly and downwardly inclined direction of the sinker
provides a gap between the tip of the sinker knitting ledge
15a and the needles
2,3. Therefore, a knitted fabric can pass between the gap. Thus, the winding tension
is more readily applied to the knit fabric which results in the potential for higher
quality and a larger knit fabric thickness.
[0025] In the drawings and specification there has been set forth the best mode presently
contemplated for the practice of the present invention, and although specific terms
are employed, they are used in a generic and descriptive sense only and not for purposes
of limitation, the scope of the invention being defined in the claims.