US3688525A

US3688525A - Flat bed knitting machines

Info

Publication number: US3688525A
Application number: US92993A
Authority: US
Inventors: Keith Jeffcoat
Original assignee: Courtaulds PLC
Current assignee: Akzo Nobel UK PLC
Priority date: 1969-12-01
Filing date: 1970-11-27
Publication date: 1972-09-05
Anticipated expiration: 1989-09-05
Also published as: ES386064A1; DE2059094A1; BE759655A; CH535309A; GB1323557A; FR2072714A5

Abstract

A flat bed knitting machine comprises a needle bed, a yarn feeder arranged to traverse the needle bed and to feed yarn to the needles of the needle bed from a stationary yarn package, means for forming a loop in the yarn prior to its passage through the yarn feeder, and means for varying the length of the loop in timed relation to the traversing movements of the yarn feeder for the purpose of preventing any substantial build-up of tension in the yarn. The provision of such a loop prevents tightening of the end stitches of a piece of fabric being knitted on the machine.

Description

United States Patent [151 3,688,525

Jeffcoat 1 Sept. 5, 1972 [54] FLAT BED KNITTING MACHINES 1,718,835 6/ 1929 Rolston ..66/ 146 Inventor: J Nuneaton, England 3,5 Brown et 3.]. [73] Assignee: Courtaulds Limited, London, En- Primary ExaminerRona1d Feldbaum gland Att0rneyDavis, Hoxie, Faithfull & Hapgood [22] Filed: Nov. 27, 1970 [57] ABSTRACT [21] Appl' 92993 A flat bed knitting machine comprises a needle bed, a yarn feeder arranged to traverse the needle bed and to [52] us. C1. ..66/146, 66/126, 66/125 feed y t0 the d s f t needle b d from a sta- 51 Int. Cl. ...D04b 15/44, D04b 27/12, D04b 27/14 tionary y p g means for forming a p in the [58] Field of Search ..66/125, 126, 127, 128, 146, yam P to t Passage through the y m feeder, and

66/60 64 means for varying the length of the loop in timed relation to the traversing movements of the yarn feeder [56] References Cited for the purpose of preventing any substantial build-up of tension in the yarn. The provision of such a loop UNITED STATES PATENTS prevents tightening of the end stitches of a piece of f k 'tt (1 th h' 381,898 5/1888 Appleton ..66/146 abnc bemg e e mac me 2,710,529 6/1955 Piltz ..66/146 22 Claims, 14 Drawing Figures PATENTEDSEP 51912 SHEET U10F12 NN Wing-M &

IN VE N TOR KEITH JEFFCOAT sum 02 or 12 PATENTEDSEP 5 1972 IN VE N T OR KEITH JEFFCOAT PATENTEDSEP 5 I972 sum 03 or 12 IN VE N TOP KEITH JBFFCOAT PATENTEUSEP 5 m2 saw on or 1 INVENTOR KEITH JEFFCOAT PA'TIENTEDSEP 5 1912 SHEET OSUF 12 IN VE N T 0!? KEITH JEFFCOAT PATENTEDSEP 51972 SHEET as or 1 um mm mm a 1 IN VENTOP KEITH JEFFCOAT A E TEDsEP' 5 I972 SHEET 070F 12 INVENTOR KEITH JEFFCOAT PATENTEDSEP 51912 sum OBOF 12 INVENTOP KEITH JEFFCOAT PATENTEDSEP 51912 SHEET USUF 12 PATENTEDSEP' 5 I912 3.688.525 SHEET 100F 12 119 1193 up [76 12p L Z1 415 l FLAT BED KNITTING MACHINES This invention is concerned with the supply of yarn to the needles in flat bed knitting machines with independently operated needles and is particularly useful in machines used to knit fabric or articles of varying width.

In a flat bed knitting machine in which yarn is supplied to the carrier from one end of the beds the carrier can overrun the edge of the knitting when moving towards the yarn supply without causing any difficulty due to increasing tension in the yarn and tightening of the end stitches.

However, when the carrier overruns the edge of the knitting travelling in the opposite direction, yarn is drawn from the supply under increasing tension and thus the tension applied to the edge loops of the knitting increases and these loops tighten. This problem becomes more serious when the yarn carrier supplying the yarn to the needles moves between fixed stops on the carrier rail whilst the knitting width is decreased. If the yarn is fed from a central position relative to the needle beds, the problem occurs, at a reduced level, at both ends of the carrier traverse.

The invention provides an arrangement for overcoming this problem and consists in a flat bed knitting machine comprising a needle bed, a yarn feeder arranged to traverse the needle bed and to feed yarn to the needles of the needle bed from a stationary yarn package, means for forming a loop in the yarn prior to its passage through the yarn feeder, and means for varying the length of the loops in timed relation to the traversing movements of the yarn feeder for the purpose of preventing any substantial build-up of tension in the yarn.

The yarn may be led to the yarn feeder from the stationary yarn package via a plurality of yarn guides and variation of the length of said loop may be effected by causing relative movement between at least two of the guides in timed relation to the traversing movements of the yarn feeder. Thus, in one embodiment of a V-bed knitting machine in accordance with the invention a first yarn guide is arranged to traverse the needle beds, and further yarn guides are arranged to guide yarn from the yarn package and feed it in a direction along the needle beds, from one end of the portion of the beds traversed by the feeder, past the yarn feeder to said first yarn guide whence the yarn passes back to the yarn feeder and then to the needles. One of these further yarn guides is conveniently mounted on the yarn feeder. The yarn feeder and said first yarn guide are arranged to traverse the needle beds in such a way that along part of each traverse of the beds they move together with a loop of yarn formed between the yarn feeder and the first yarn guide. However, as the yarn feeder approaches the end of a traverse in the direction away from said one end of the feeder traverse, the yarn feeder moves closer to said first yarn guide and takes yarn from said loop so that tightening of the yarn does not occur. On reversing its movement, the yarn feeder moves away from said first yarn guide to re-establish a loop of yarn between the yarn feeder and said first yarn guide, whereafter the yarn feeder and the first guide move together once more to traverse the beds in the opposite direction. The yarn feeder and said first yarn guide may be mounted on separate members, for example, yarn carriers each slidable on an elongated support, for example a carrier rail, having its axis parallel to the needle beds.

There may be means for interconnecting the two members so that the two can be moved simultaneously by means of one collector peg engaging the member on which the yarn feeder is mounted, a device providing a lost motion between the members at one end of the beds being arranged to allow the member on which the yarn feeder is mounted to move closer to the member on which said first yarn guide is mounted at this position. Alternatively, the two members may be mounted on separate rails (or on different sides of a double-sided rail) and may be moved by separate collector pegs and halted by different stops in order to procure the desired relative movement near one end of the portion of the beds traversed by the feeder.

In another embodiment of the knitting machine according to the invention, the yarn is led to the yarn feeder from the stationary yarn package via a plurality of yarn guides mounted on a support fixed to a stationary part of the machine and one of the guides is mounted for movement on the support relative to the other guides. Movement of the movable guide may be effected by a linear movement device, for example, a pressure-fluid operated piston and cylinder assembly the actuation of which is controlled in timed relation to the traversing movement of the yarn feeder. Alternatively, the movable guide may be moved by a cam track which moves with the yarn feeder. In yet another embodiment the plurality of yarn guides may be mounted on a support which traverses the needle bed with the yarn feeder. In this case one of the yarn guides would be movably mounted on the support, movement of this yarn guide being effected, for example, by a cam track fixed to a stationary part of the machine.

The invention will be further described, by way of example, with reference to the accompanying drawings, in which:

FIG. 1 is a perspective view of two yarn carriers on a carrier rail in a first embodiment of a flat bed knitting machine according to the invention;

FIG. 2 to 4 are side views of the carriers and rail of FIG. I showing the carriers in various positions,

FIG. 5 is a plan showing a part of a double-sided carrier rail in a second embodiment of a flat bed knitting machine according to the invention, two carriers being mounted on the rail,

FIGS. 6 to 8 are side views of the rail and carriers of FIG. 5 showing the carriers in various positions,

FIG. 9 is a view similar to FIG. 2, of a carrier rail in a third embodiment of a flat bed knitting machine according to the invention,

FIGS. 10 and l 1 are schematic side views of a carrier rail in a fourth embodiment of a flat bed knitting machine according to the invention,

FIGS. 12 and 13 are views similar to FIGS. 10 and 1 1, respectively, relating to a fifth embodiment of a flat bed knitting machine according to the invention, and

FIG. 14 is a view similar to FIG. 10 relating to a sixth embodiment of a flat bed knitting machine according to the invention.

The first embodiment. of the invention to be described with reference to FIGS. 1 to 4 is a flat V-bed knitting machine (the majority of which is not shown) comprising a carrier rail which is mounted in a conventional manner so as to extend parallel to and above the needle beds (not shown). Two

yarn carriers

11 and 12 are slidably mounted on the rail 10 for movement between

stops

13 and 13. The whole length of the rail 10 between the stops is not shown in FIGS. 1 to 4. This is indicated in FIG. I by a break in the rail. FIGS. 2 to 4 of the drawings are not to scale in that the length of the rail between the stops is shown as being much shorter than would normally be the case in relation to the size and spacing of the carriers.

On the carrier 12 is an arm 14 on which is mounted a guide for the yarn in the form of a ceramic eyelet 15 having a circular cross-section and mounted, in this embodiment of the invention, with its axis perpendicular to a plane containing the axis of the rail 10.. Yarn 16 is fed to the guide 15 in a direction parallel to the rail 10 and parallel to the needle beds. The yarn passes through the guide 15 and back to a guide 17, again in the form of a ceramic eyelet, mounted on an arm 18 on the carrier 11. From the guide 17, the yarn 16 passes to a yarn feeder 19 also mounted on the arm 18 and from there it goes to the needles.

The yarn is guided to the eyelet 15 from a stationary package (not shown) on the machine by further guides including an eyelet 22 mounted, in the present embodiment, near one end of the carrier rail 10 and an eyelet 23 mounted on the arm 18 of the carrier 11. The yarn is thus guided to the eyelet 15 in a direction along the needle beds from one end of the portion of the needle beds traversed by the yarn feeder 19. The eyelet 22 need not be located at the end of the needle beds but may be located at or near one end of the said portion of the needle beds. For example a machine may be used to knit several articles simultaneously using a corresponding number of sets of yarn carriers and yarn may then be supplied separately to the separate portions of the beds traversed by the carriers of the corresponding sets.

The two

carriers

11 and 12 are connected to one another for movement along the rail 10 by means of a catch 24 comprising a metal block 25 having a slot 26 formed in it, the slot extending in a direction across the needle beds. The block 25 is secured by screws to one end of a resilient strip 27 made, for example, of nylon. The other end of the strip 27 is secured by screws 21 to the arm 18 of the carrier 11. Beneath the strip 27 is secured a stiff metal backing plate 28 shaped to allow a fixed amount of downward movement of the strip. The plate 28 serves to support the strip 27 and to damp its oscillations.

An upwardly projecting bracket 29 carrying a cam plate 30 is secured to the stop 13 by screws 32. The cam plate 30 is secured to the bracket 29 by screws 33 and has an upwardly curved end portion 31.

A slot 34 formed in the carrier 11 is arranged to receive a collector peg 35 mounted on a cam box of the machine. The collector peg 35 is moved so as to project out of the cam box in order to engage in the slot 34 and move the carrier 11 in the usual way.

When the carrier 12 approaches the end stop 13, as shown in FIG. 1, a bevelled edge 36 on the block engages under the upwardly curved portion 31 of the cam plate 30. The resilient strip 27 then yields allowing the block 25 to move downwardly, thereby disengaging the carrier 12 from the carrier 11 which is pushing the carrier 12 along the rail 10. The carrier 12 is therefore halted by the stop 13 whereas the carrier 11 continues the move to the left in F 10. 1 until the collector peg 35 is pushed out of the slot 34 by a bevelled surface 39 on the carrier 12. The carrier 11 is then brought to rest against the carrier 12. When the carrier 11 is once more engaged by the collector peg 35 on the reverse movement of the cam box, the carrier 11 at first moves away from the carrier 12 until a raised portion 37 on the block 25 engages the arm 14 causing the carrier 12 to move to the right with the carrier 11. As soon as the block 25 is moved from beneath the cam plate 30, the resilient strip 27 urges the block upwardly so that the arm 14 is once more located in the slot 26. The strip 27, block 25 and cam plate 30 thus provide a lost motion between the two carriers at the end of the rail 10 at which the stop 13 is located.

The effect of this lost motion together with the manner in which the yarn is guided to the guide 15 and the feeder 19 is illustrated in FIGS. 2 to 4.

FIG. 2 shows the feeder 19 at the end of the rail 10 from which the yarn 16 is supplied to the guide 15. The guide 15 is on the side of the feeder 19 remote from this end of the rail. Below the rail 10 is shown a piece of knitted fabric 38 which has been shaped by narrowing. The stop 13' is arranged to arrest the carrier 11 at a point just beyond the edge 41 of the widest part of the fabric 38, a bevelled surface on the stop 13' pushing the collector peg out of the slot 34 in the usual way. At this end of the feeder traverse the carrier 12 is not disconnected from the carrier 11, the two carriers remaining the same distance apart at the stop 13' as when traversing the beds. No yarn is taken from the yarn package due to the overrun of the feeder 19 beyond the edge of the fabric, whether at 41 or at the point 42 where the narrowest part of the fabric has been reached since during this overrun the yarn feeder merely moves along yarn already drawn from the package and extending from the knitting to the package.

In FIG. 3, the carrier 12 is shown at the end stop 13 and the block 25 has just been disengaged from the arm 14 by the cam plate 30. The carrier 12 has thus been arrested before the feeder 19 has moved past the edge of the knitting whereas the carrier 11 and the feeder 19 continue to move to the left and therefore move closer to the carrier 12. The feeder 19 continues to move to the left until the peg 35 is disengaged from the carrier 11, as explained with reference to FIG. 1, and the carrier 11 comes to rest against the carrier 12.

This situation is shown in FIG. 4 and it will be seen that during this movement, no yarn is taken from the package even when knitting only to the point 43 at the edge of the narrowest part of the fabric, since once more the feeder 19 is moving along a loop of yarn already drawn from the package. To achieve this the carrier 12 is halted when the feeder 19 is on the side of the point 43, that is the edge of the narrowest part of the fabric, remote from the carrier 12.

In the embodiment of the invention to be described with reference to FIGS. 5 to 8, two

carriers

51 and 52 are mounted on opposite sides of a double-sided carrier rail 53 in a flat V-bed knitting machine (not shown). A yarn guide 54 is carried on an arm 55 secured to the carrier 52 and extending from the carrier 52 in a direction parallel to the rail 53. On the carrier 51 is mounted a yarn feeder 56, which guides the yarn to the needles, and a yarn guide in the form of a ceramic eyelet 57 also mounted on the carrier 51 guides the yarn from the guide 54 to the feeder 56. Yarn 65 is supplied to the guide 54 in a direction along the beds from one end of the portion of the beds traversed by the yarn feeder. The yarn is supplied from a package (not shown) to the guide 54 through further guides including a ceramic eyelet 58 on the carrier 51 (FIG. 6).

Stop blocks 61 and 62 are mounted on the side 53' of the carrier rail 53, this being the side on which the carrier 51 is mounted. Stops 63 and 64 are mounted on the other side 53" of the rail 53.

In FIG. 6, the two

carriers

51 and 52 are side by side near the end of the feeder traverse from which the yarn 65 is supplied, the carrier 51 being partly obscured behind the carrier 52. In this position, the two carriers are engaged by collector pegs 66 and 67 (FIG. 5) on their associated cam boxes and are moved together towards the opposite end of the rail. During this movement the guide 54 is maintained at a fixed distance from the feeder 56. FIG. 7 shows the position at the opposite end of the machine at which the collector peg 66 is disengaged from the carrier 52 which is arrested by the stop 63 before the feeder 56 has moved past the edge of the knitting. Thereafter the carrier 51 continues to move to the left in FIG. 6 moving the feeder 56 closer to the guide 54 until the collector peg 67 is disengaged from the carrier 51 and the latter is arrested by the stop 61. At the next traverse of the cam boxes in the opposite direction, the carrier 51 is picked up first and begins to move to the right before the carrier 52. Thereafter the carrier 52 is picked up and is moved to the right in FIG. 8 together with the carrier 51. The effect on the takeoff of yarn is the same in this embodiment as in the embodiment of FIGS. 1 to 4.

In a modified embodiment of the knitting machine of FIGS. 5 to 8 the cam boxes are constructed so that the collector pegs 66 and 67, instead of being opposite one another as shown in FIG. 5, are spaced apart in the direction of the rail 53. It is then possible to make the arm 55 shorter than in the embodiment of FIGS. 5 to 8, so that the overall length of the yarn carriers is reduced.

The ceramic eyelets located at or near one end of the feeder traverses in the embodiments described above may be replaced by pulley wheels, as may the eyelets on the carriers and other eyelets for guiding the yarn. Pulley wheels on the carriers may be driven at a speed related to the speed of carrier movement, for example by a drive taken from the carrier rail by a rubber driving wheel frictionally engaged with the rail and the pulley.

In the embodiment of the invention to be described with reference to FIG. 9, a yarn feeder 70 is mounted on a carrier 71 and the latter is arranged to traverse along the needle beds (not shown) of the machine on a carrier rail 72. The feeder 70, the carrier 71 and the rail 72 may be of substantially the same construction as the corresponding items in the embodiment of FIG. 1. The movement of the carrier 71 along the rail 72 is limited by stops 73, 74, the positions of which along the rail can be adjusted. The stops 73, 74 may be of substantially the same construction as the corresponding items in the embodiment of FIG. 1.

Two elongated supports in the form of

rods

75, 76 joined together in spaced, parallel relationship by

support members

77, 78, are disposed parallel to and spaced from the carrier rail 72, the

support members

77, 78 being fixed relative to the frame of the knitting machine. A block 79 is slidably mounted on the two

rods

75, 76, the latter being a sliding fit in two

parallel bores

80, 81 in the block.

A third rod 82 is a sliding fit in a third bore 83 in the block 79, the axis of the bore 83 being parallel to the axes of the

bores

80, 81. At its end remote from the block 79 the rod 82 enters a bore 84 in a block 85 secured to the carrier 71 by screws 86. The rod 82 is clamped in the bore 84 by a screw 87.

A fourth bore 88 in the block 79 has its axis disposed in a plane perpendicular to the axes of the

bores

80 and 83, the bore 88 communicating with the

bores

80 and 83. A locking means in the form of a ball 89 is housed in the bore 88, this ball having a diameter slightly smaller than the bore 88 and slightly larger than the width of the gap 90 between the confronting surfaces of the

rods

75 and 82. The ball 89 rests on the rod 75 and projects slightly into the bore 83 where it is received in a recess 91 formed in the rod 82 at the end of the latter remote from the carrier 71. As will become apparent hereinafter, the ball 89 serves as a releasable locking means for locking the block 79 either to the rod 82 or to the rod 75.

The rod 75 has a recess 92 formed therein which is disposed close to the stop 74 by suitably adjusting the axial position of the rod 75 relative to the

support members

77, 78. For this purpose the rod 75 is clamped in the

support members

77, 78 by screws 93 which can be slackened to allow axial adjustment of the rod.

Yarn 94 is led to the yarn feeder 70 from a stationary yarn package (not shown) via a yarn guide 95 mounted on the arm 96 of the carrier 71, a yarn guide 97 mounted on an arm 98 secured to the block 79 and a yarn guide 99 also mounted on the arm 96. The arms 96 and 98 are constructed in substantially the same way as the

arms

18 and 14, respectively, of the embodiment of FIG. 1.

FIG. 9 shows the feeder 70 at the end of the rail 72 from which yarn 94 is supplied to the guide 97. The stop 73 is arranged to arrest the carrier 71 with the feeder 70 just beyond the edge 41 of the widest part of a piece of knitted fabric 38 being knitted on the machine. As the carrier 71 moves to the position shown in FIG. 9 in the direction of the arrow A, no yarn is taken from the yarn package due to the overrun of the feeder 70 beyond the edge of the fabric, since during this overrun the yarn feeder merely moves along yarn already drawn from the yarn package and extending from the knitting to the package.

On the return movement of the carrier 71 along the rail 72 in the direction of the arrow B, the block 79 moves with the carrier for part of the carrier movement owing to the rod 82 being locked to the block 79 by the ball 89 engaging in the recess 91. A loop 100 of yarn then exists between the guide 97 and the

guides

95 and 99.

When the block 79 reaches the position shown in chain lines in FIG. 9 (and designated 79a), the ball 89 drops from the recess 91 in the rod 82 and enters the recess 92 in the rod 75. This locks the block in the position 79a and simultaneously releases the rod 82 from the block 79 so that the carrier 71 can still move in the direction of the arrow B while the block 79 remains stationary, the rod 82 then sliding through the bore 83.

During this movement of the carrier 71 relative to the block 79, no yarn is taken from the package even when knitting stops at the point 43 at the edge of the narrowest part of the fabric, since the feeder 70 is moving along yarn of the loop 100 already drawn from the package. The length of this loop becomes progressively shorter as the carrier 71 moves up to the stop 74.

When the carrier 71 begins its next movement away from the stop 74 in the direction of the arrow A, the block 79 remains in the position 790 until a pin 101 in the end of the rod 82 engages the block and carries it away in the direction of the arrow A. The ball 89 is raised out of the recess 92 and enters the recess 91 to lock the rod 82 to the block 79 once more. The loop 100 is then restored to the length shown in FIG. 9.

Although in the embodiment shown in FIG. 9 the block 79 is arranged to slide on two

rods

75, 76, it will be appreciated that the rod 76 may be dispensed with if the block 79 is mounted on the rod 75 in such away that it cannot rotate on the rod. For example the rod 75 and the bore 80 may each be given a non-circular cross-section.

The point in the traversing movement of the carrier 71 in the direction of the arrow B at which the block 79 is stopped can be adjusted by adjusting the rod 82 axially relative to the carrier 71 at the block 85.

In the embodiment of the invention to be described with reference to FIGS. and 11, a yarn feeder 110 is mounted on a carrier 111 and the latter is arranged to traverse along the needle beds (not shown) of the machine on a carrier rail 112. Stops (not shown) limit the movement of the carrier 111 as in the previously described embodiments.

Two fixed yarn guides 113, 114 are secured to the carrier 111 and a third yarn guide 115 is secured to a slide block 116 which is slidably mounted in a slot 117 in the carrier 111. A cam follower 118 on the block 116 is engaged in a cam track 119 in a stationary plate 120 fixed relative to the frame of the knitting machine. The track 119 has a portion 119a disposed parallel to the rail 112 and an inclined portion 119b.

Yarn 121 is fed to the feeder 110 from a stationary yarn package (not shown) via the yarn guides 113, 115 and 114 so that a loop 122 of yarn is formed between the guide 115 and the

guides

113 and 114.

FIG. 10 shows the position of the parts when the carrier 111, moving in the direction of the arrow C, is approaching the end of a traversing movement, with the cam follower 118 just entering the inclined portion 1 19b of the cam track. Further movement of the carrier 111 in the same direction results in the cam follower 118 moving the slide block 116 and the yarn guide 115 towards the yarn guides 1 13 and 114 so that the loop 122 is shortened, as shown in FIG. 11. The yarn carrier 111 can therefore overrun the knitted fabric 38 without any substantial build-up of tension in the yarn occurring, and consequently there is no objectionable tightening of the last stitch of the knitting at the point 42 of the fabric.

The position of the plate may be adjusted in the longitudinal direction of the carrier rail 112 for the purpose of adjusting the position, longitudinally of the needle beds, at which shortening of the loop 122 commences.

FIGS. 12 and 13 show a modification of the embodiment of FIGS. 10 and 11 in which the yarn guides 113, 114 and 115 are mounted on a plate 125 fixed relative to the frame of the machine. The

guides

113 and 114 are fixed to the plate 125 while the guide 115 is mounted on a slide block 116 which is slidable in a slot 117 in the plate 125. A cam follower 118 on the slide block 116 enters a cam track 126 in a plate 127 which is arranged to traverse along the machine in timed relation with the movements of the carrier 1110 along the carrier rail 112. The cam track 126 has a portion 126a disposed parallel to the carrier rail 112 and an inclined portion 12Gb.

The embodiment of FIGS. 12 and 13 functions in substantially the same way as that of FIGS. 10 and 11, in this case movement of the plate 127 causing movement of the guide 115 in a direction to effect a shortening of the yarn loop 122 as the carrier 111a approaches the end of a traversing movement in the direction of the arrow C. Again there is no objectionable tightening of the last stitch of the knitting at the point 42 of the fabric 38.

The position of the plate 125 may be adjusted in the longitudinal direction of the carrier rail 112 for the purpose of adjusting the position, longitudinally of the needle beds, at which shortening of the loop 122 commences.

Finally, FIG. 14 shows a modification of the embodiment of FIGS. 12 and 13 in which the slide block 116 carrying the movable yarn guide 115 is moved by a pneumatic piston and cylinder assembly 130 instead of by the cam track 126 of FIGS. 12 and 13.

In FIG. 14 the free end of the piston rod 131 of the assembly 130 is joined to the slide block 116 and reciprocation of the piston rod is controlled by a valve unit 132 incorporated in the assembly 130. Actuation of the valve unit 132 is in turn controlled by two

limit switches

133 and 134, for example microswitches, arranged to be actuated by an actuating member carried by the yarn carrier 11112.

With the yarn carrier 111b moving the yarn feeder 110 along the rail 112 in the direction of the arrow C a long loop 122 of the yarn 121 exists between the guide 115 and the

guides

113 and 114, the piston rod 131 being drawn into the assembly 130. When the actuating member 135 actuates the switch 133 the valve 132 causes the piston rod 131 to move out of the assembly 130 at a controlled rate proportional to the traversing speed of the yarn carrier 1111;. This has the effect of moving the slide block 116 in the groove 117 in the direction of the arrow D from the position shown so as to shorten the loop 122. When the carrier 1 1 1b reaches the end of its traversing movement in the direction of the arrow C the switch 134 is actuated to stop the piston rod 131. The yarn carrier is thus able to overrun the fabric 38 without any objectionable tightening of the end stitch at the point 42.

When the carrier 111b commences its return traversing movement, the switch 134 is again actuated to initiate withdrawal of the piston rod 131 into the assembly 130 so that the yarn guide 115 is moved back to the position shown in FIG. 14 in which the loop 122 is restored to its original length. When the switch 133 is again actuated the piston rod 131 comes to rest.

The positions of the

switches

133 and 134 can be adjusted longitudinally of the carrier rail 112 so that the points at which alteration of the length of the loop 122 commences and stops can be adjusted.

It will, of course, be appreciated that the pneumatic piston and cylinder assembly 130 may be replaced by other linear movement devices of electric or hydraulic nature.

If the extensibility of the yarn 121 is greater than usual, it may be advantageous to alter the length of the loop 122 at a slightly different rate from the rate of travel of the yarn carrier lllb. This can be done by suitably designing the linear movement device which moves the yarn guide 115.

In all of the above described embodiments it is preferred to arrange for the yarn loop to become progressively shorter throughout a distance corresponding to the maximum overrun of the yarn carrier which supports the yarn feeder. If the actual overrun is less than this maximum overrun the loop shortening will commence while knitting is still taking place and this has its advantages.

What is claimed is:

1. A flat bed knitting machine comprising a needle bed, a yarn feeder arranged to traverse the needle bed and to feed yarn to the needles of the needle bed from a stationary yarn package, means for forming a loop in the yarn prior to its passage through the yarn feeder and means for varying the length of the loop in timed relation to the traversing movements of the yarn feeder so as to draw yarn from said package substantially only when knitting is taking place.

2. A flat bed knitting machine as claimed in claim 1, in which said loop forming means comprises a plurality of yarn guides for guiding the yarn to the yarn feeder and in which the means for varying the length of the loop comprises means for causing relative movement between at least two of the guides in timed relation to the traversing movements of the yarn feeder.

3. A flat bed knitting machine as claimed in claim 2, comprising means for causing a first of said yarn guides to traverse the needle bed and means positioning further of said yarn guides to guide yarn from the yarn package and feed it in a direction along the needle bed, from one end of the portion of the bed traversed by the feeder, past the yarn feeder to said first yarn guide and thence to the yarn feeder.

4. A fiat bed knitting machine as claimed in claim 3, comprising means for moving at least one of said further yarn guides with the yarn feeder.

5. A flat bed knitting machine as claimed in claim 3, comprising means for causing the yarn feeder and said first yarn guide to traverse the needle bed in the same direction spaced apart a substantially constant distance along part of each traverse of the bed and means for causing the yarn feeder to move closer to said first yarn guide as the yarn feeder approaches the end of a traverse in the direction away from the said one end of the feeder traverse and then, on reversing its movement, for causing the yarn feeder to move away from said first yarn guide whereafter the yarn feeder and said first yarn guide again move in the same direction spaced apart a substantially constant distance to traverse the bed in the opposite direction.

6. A flat bed knitting machine as claimed in claim 5, in which the yarn feeder and said first yarn guide are mounted on separate members each slidable on an elongated support having its axis parallel to the needle bed.

7. A fiat bed knitting machine as claimed in claim 6, comprising means for interconnecting the two members so that the two can be moved simultaneously by means of one collector peg engaging the member on which the yarn feeder is mounted.

8. A flat bed knitting machine as claimed in claim 7, comprising a device providing a lost motion between the two members at one end of the beds so as to allow the member on which the yarn feeder is mounted to move closer to the member on which said first yarn guide is mounted at this position.

9. A flat bed knitting machine as claimed in claim 6, in which the two members are slidable on the same elongated support.

10. A flatbed knitting machine as claimed in claim 6, in which the two members are slidable on separate elongated supports.

11. A flat bed knitting machine as claimed in claim 6, in which said members are yarn carriers and said elongated support or supports are carrier rails.

12. A flat bed knitting machine as claimed in claim 6, in which the two members are yarn carriers slidable on different sides of a double-sided carrier rail.

13. A flat bed knitting machine as claimed in claim 10, in which the two members are moved by separate collector pegs and halted by different stops in order to procure the desired relative movement near one end of the portion of the bed traversed by the feeder.

14. A flat bed knitting machine as claimed in claim 2, comprising a support fixed to a stationary part of the machine for supporting the yarn guides and means for mounting one of the guides for movement on the support relative to the other guides.

15. A flat bed knitting machine as claimed in claim 14, in which movement of the movable guide is effected by a linear movement device the actuation of which is controlled in timed relation to the traversing movement of the yarn feeder.

16. A flat bed knitting machine as claimed in claim 14, in which the movable guide is moved by a cam track which moves with the yarn feeder.

17. A flat bed knitting machine as claimed in claim 2, comprising a support for supporting the yarn guides and means for causing the support to traverse the needle bed with the yarn feeder.

18. A flat bed knitting machine as claimed in claim 17, in which one of the yarn guides is movably mounted on the support, movement of this yarn guide being effected by a cam track fixed to a stationary part of the machine.

19. A flat bed knitting machine as claimed in claim 10, comprising a rod disposed substantially parallel to the axes of said supports and interconnecting said two members, the rod being secured to one of the members and being connected to the other member by a releasable locking means.

support as the yarn feeder approaches the end of a traverse in the direction away from said one end of the feeder traverse.

22. A flat bed knitting machine as claimed in claim 20, in which said locking means is a ball housed in a bore in said other member.

TED STATES PATENT oFFicE QETl-HCATE r crew Patent No. 3,688,525 Dated September 5, 1972 InventorQ) KEITH JEFFCOAT It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

The heading of the patent should contain the following: 1

Claims priority of British application 58508/69 filed December 1, 1969.

Col. 7, line 25, "away" should read a way' Signed and sealed this 8th day of May 1973.

(SEAL) Attest:

EDWARQMFLETCHERJR. ROBERT GOTTSCHALKv Attestlng Officer Commissioner of Patents

Claims

4. A flat bed knitting machine as claimed in claim 3, comprising means for moving at least one of said further yarn guides with the yarn feeder.

7. A flat bed knitting machine as claimed in claim 6, comprising means for interconnecting the two members so that the two can be moved simultaneously by means of one collector peg engagiNg the member on which the yarn feeder is mounted.

10. A flat bed knitting machine as claimed in claim 6, in which the two members are slidable on separate elongated supports.

20. A flat bed knitting machine as claimed in claim 19, in which said releasable locking means is mounted in said other member and is engageable either in a recess in said rod or in a recess in the support on which said other member is slidable.

21. A flat bed knitting machine as claimed in claim 20, in which said locking means unlocks the rod from said other member and locks said other member to its support as the yarn feeder approaches the end of a traverse in the direction away from said one end of the feeder traverse.