GB2199854A

GB2199854A - Sewing machine

Info

Publication number: GB2199854A
Application number: GB08729371A
Authority: GB
Inventors: John Van Eyk
Original assignee: Union Special Corp
Current assignee: Union Special Corp
Priority date: 1985-05-31
Filing date: 1987-12-16
Publication date: 1988-07-20
Anticipated expiration: 2007-12-16
Also published as: AU5835986A; GB2199854B; GB8729371D0; AU582657B2

Abstract

An apparatus for cutting and positioning a chain of stitches for stitching onto material in a sewing machine having a needle and a needle rate (20) comprises a cutting knife adapted to sever the chain (18) of stitches after the chain has been sewn onto the material, a nozzle (14) for blowing the severed chain to a position in advance of the needle, and a gripping device (16) adapted to be positioned at a level below the needle plate (20) during sewing of the chain stitches onto the material, and to rise up and grip the thus positioned severed chain, and return to below the level of the needle plate (20) to hold the chain, to effect incorporation of the chain during the initial stitches into the seam being formed. The gripping device (16) comprises a movable plate (40), and a nipper (42) resiliently biassed towards the plate (40) to grip the chain (18) between a finger (108) on the nipper and the plate (40) when the nipper is retracted (Fig. 12) and the nozzle (14) blows the chain onto the finger (108) when the latter is extended (Fig. 11). A movable guide (44) applies additional bias to the nipper (42) until the plate (40), nipper (42) and guide (44) are all retracted below the needle plate (20). <IMAGE>

Description

DESCRIPTION SEWING MACHINE The present invention relates to an apparatus for use with a sewing machine to cut a chain of stitches, trailing from a sewn garment and hold the cut chain in a predetermined location so as to be positioned to be incorporated into the leading portion of the seam of the next garment to be sewn.

Sewing machines which form seams utilizing chain stitches on a succession of pieces of material with the seam being continued into the area between the pieces of material, are well-known. With seams of this type, means are provided for detaching the pieces of material one from the other by appropriate automatic cutting devices which cut the chain after the sewn pieces have been caused to travel beyond the needle and the presser foot of the machine.

By cutting the chain of stitches with such means, one ortion of minimal length remains attached to the stitched piece of material and the other, being connected to the needle plate, is manipulated to a position forwardly of the needle so that it can be sewn into the initial portion of the seam which will be formed on the next piece of material or workpiece.

This procedure prevents a slackening of the seam's initial stitches which would give the leading edge of the workpiece an undesirable appearance.

The known devices for performing this function include a chain-cutting device disposed adjacent the stitch finger of the needle plate which co-operates with a chain-orienting device and gripper apparatus located forwardly of the needle and usually adjacent the forward portion of the needle plate.

These apparata suffer from the disadvantage that, because the portion of the chain to be sewn onto the next garment is located on the upper surface of the needle plate adjacent the needle hole, the gripping apparatus is frequently accidentally displaced while positioning the next workpiece in the sewing area.

The material to be sewn interferes with the chain, preventing the proper insertion of the latter into the new seam being sewn, due to the pressure and friction of the piece of material of the chain which tends to dislodge the chain from the gripping apparatus and move it towards the trimmer knife of the machine which knife is adjacently disposed, thereby hindering subsequent handling of the chain.

An object of the present invention is the provision of an improved sewing machine.

The sewing machine has an apparatus for cutting and positioning a chain of stitches for stitching onto material in the machine having a needle and a needle plate, comprising a cutting knife adapted to sever the chain of stitches after the chain has been sewn onto the material, positioning means adapted to move the severed chain to a position forwardly of the needle, and gripping means adapted to grasp the severed chain.

A feature of the present invention is that the gripping means is normally positioned below the needle or hole plate of the sewing machine.

Another feature of the invention is that the gripping means rises above the needle plate to receive and grasp the severed chain.

Yet another feature of the invention is that the severed chain is grasped below the level of the needle plate.

The present invention resides in an apparatus for cutting and positioning a chain of stitches for stitching onto material in a sewing machine having a needle and a needle plate, comprising: means for cutting the chain of stitches; means for positiining the severed chain in advance of the needle; a nipper having an outwardly directed finger; means for moving the nipper between a first position with the finger located beneath the needle plate and a second position with the finger located above the needle plate; a plate having a forwardly directed end; and means for moving the plate between a first position with the end located beneath the needle plate, and a second position with the end located adjacent the needle plate, said finger catching the severed chain and drawing it to a position between the finger and plate to releasably grasp the chain.

A further aspect of the invention is that the chain is grasped and held in a taut configuration.

Another aspect of the invention is that the severed chain is grasped with varying gripping forces.

The invention is further described, by way of example, with reference to the accompanying drawings, in which: Fig.l is a schematic perspective view of a chain stitch overedge sewing machine, Figs. 2 to 5 illustrate in simplified form the cycle of operation of the thread cutting and positioning apparatus of the machine of Fig.l; Fig.6 is a side elevational view, partly broken away, of thread gripping apparatus according to the invention for the sewing machine of Fig.l; Fig.7 is a fragmentary top plan view of the gripping apparatus of Fig.6; Figs. 8 to 12 are fragmentary perspective views showing operation of the gripping apparatus of Figs. 6 and 7; and Fig.13 is a fragmentary plan view of a fabric stitched with the sewing machine of the present invention.

As the general construction and operation of a sewing machine, which may be of Federal Stitch Type 504, to which the present invention is applicable, is well-known and familiar to those conversant in the art, and as the invention is primarily concerned with a device for positioning and gripping a chain of stitches for incorporation into the initial stitches of a new seam, only those parts which are directly concerned with a preferred form of the invention are described and illustrated in detail.

As shown in Figs. 1 and 2, after the chain 10 is sewn onto the material 11, a clamp 21 moves away from a needle 15 and the presser foot 30 and pulls the threads off the stitch finger or tongue 23. Light is emitted by a light emitter 12a, and a light detector 12b senses a change of reflectivity from a lower surface, such that the detector 12b senses the end of the material in response to which the cutter 13 severs the chain 10. Positioning means, in the form of a blower nozzle 14, directs a stream of air onto the severed chain to blow it back to a position in advance of the needle 15, as shown in Fig.2 by the phantom chain 18. Alternatively, the machine may have a plurality of blowers to sequentially move the chain in advance of the needle.Gripping means or apparatus 16 shown in simplified form in Figs. 2 to 5, is activated, and a hook member 17 rises to hook around the severed chain 18.

As shown in Fig.3, the cutter 13 opens with the material feed machanism 19 moving the sewn material to a conveyor (not shown).

The blower nozzle 14 shuts off and is raised. The hook member 17 returns to below the needle plate 20, clamping the severed chain in the gripping means 16.

As shown in Fig.4, a clamp 21 of the material feed mechanism opens, and the released garment is removed by the conveyor, with the clamp 21 returning to its starting position in advance of the needle 15.

Meanwhile, the gripping means 16 moves further below the needle plate 20, tensioning the chain 18. Light is emitted by a light emitter 22a (Fig.l), and a light detector 22b senses a change of reflectivity from a lower surface. When material is sensed by the detector 22b, the clamp 21 closes and the material is fed to the sewing machine, while the chain 18 is held in tension by the gripping means 16 for the initial stitching of the seam, to prevent slackening of the seam's initial stitches which would give the leading edge of the material an undesirable appearance.

As the material 11 is moved across under the needle 15 by the material feed mechanism 19, the end of the chain is pulled from the gripping means 16 and the chain 18 is sewn into the seam, and the cycle is repeated. The resulting sewn fabric is shown in Fig.13 in which the chain 18 is shown beneath the seaming or overedge stitches 29.

The gripping means 16 is operated by a single pneumatic cylinder 24 which is directly connected to the hook member 17. When the piston of the cylinder 24 pushes the hook member 17 upwardly, as shown in Fig.2, an extension 25 slides in a slot 26 of member 27 of the gripping means. Upon the hook member 17 being withdrawn, as shown in Fig.3, the extension 25 slides in the slot 26 to then abut against the member 27, whereby both the member 27 and the hook member 17 are withdrawn further below the needle plate 20 against the biassing force of the spring 28, as shown in Fig.4. Upon the hook member 17 starting its upward motion, the spring 28 returns the member 27 to its initial position below the needle plate 20.

Thus, the present invention, at all times, provides an apparatus for the cutting and the positioning of a chain stitch which ameliorates the problems of the prior art, by providing a mechanical gripping means 16 which holdes the severed chain below the level of the throat plate, with the gripping means 16 being movable between positions below and above the throat plate 20.

In an alternative form the light emitter 12a and light detector 12b may be omitted, and a time delay may be initiated or stitches may be counted after light detector 22b senses the material in order to activate the cutter 13.

The gripping apparatus according to the invention 16 is shown in detail in Figs. 6 to 12. With reference to Figs. 6 to 8, the gripping apparatus 16 has an elongated lower plate 40, an elongated resilient nipper 42, and an elongated resilient guide 44.

The plate 40 has a forward bevelled edge 46, a first elongated slot 48 with opposite first and second ends 50 and 52, a second elongated slot 54 with first and second ends 56 and 58, and an elongated third slot 60 with first and second ends 62 and 64. The plate 40 also has a rearward end 66. The plate 40 has an upwardly directed pin 68 for a purpose which will be described below.

The gripping apparatus 16 has a stationary member 70 having a cavity 72 facing the plate 40. A helical compression spring 74 is received in the cavity 72 and extends between one end 76 of the cavity 72 and the pin 68 of plate 40. In this configuration, the spring 74 is compressed and thus biasses the plate 40 forwardly through the pin 68. The stationary member 70 has a rear stop 78 against which the rearward end 66 of the plate 40 bears. The stationary member 70 has an elongated slot 80 extending therethrough and communicating with the second slot 54 of the plate 40. The stationary member 70 also has a forwardly directed cam 82 for a purpose which will be described below. The cam 82 is slidably adjustable in the stationary member 70, and may be secured at a desired position by a screw 83.

The gripping apparatus 16 has a movable retaining member 84 connected to and driven by the piston 86 of a cylinder 88. The retaining member 84 has a depending pin 90 extending through slot 80 of stationary member 70 and having a washer 92 received in the second slot 54 of plate 40. The retaining member 84 has a pair of screws 94 and 96 which fixedly secure rearward ends of the resilient nipper 42 and resilient guide 44 to the retaining member 84. The retaining member 84 has a forwardly directed flange 98 having a threaded aperture 100 to receive a screw 102 containing a nut 104 above the flange 98. The outer end of screw 102 bears upon the nipper 42 to bias the nipper 42 towards the plate 40. The screw 102 and nut 104 are adjustable in flange 98, such that the screw 102 may exert an adjustable bias against nipper 42 to accommodate threads of different diameter sizes.

The nipper 42 has an elongated bar or shank 105 connected to a forward end 106 having an outwardly directed finger 108, with the forward end 106 being located near or against the plate 40.

The guide 44 has a foward curved end portion 110 spaced from the finger 108 of the nipper 42 to define a space 112 between the nipper finger 108 and end portion 110 of the guide 44. An outer end 114 of the guide 44 is located above the shank 105 of the nipper 42. In the configuration shown, the guide 44 bears against the cam 82 which raises the end 114 of the guide 44 from the nipper 42 for a purpose which will be described below. When the nipper 42 and guide 44 are moved forwardly by the retaining member 84, as will be described below, the guide 44 becomes disengaged from the cam 82 causing the end 114 of the resilient guide 44 to engage against the shank 105 of nipper 42 causing further bias of the nipper 42 against the plate 40.

In operation, prior to severing the chain 10, the plate 40, nipper 42, and guide 44 are all located beneath the needle plate 20, as shown in Fig.8, with the forward end of the nipper 42 located adjacent the forward end of the plate 40. With reference to Figs.6, 7 and 9, shortly before or after the chain 10 is severed, the cylinder 88 is activated causing forward movement of the retaining member 84 and retained nipper 42 and guide 44. At the same time, the pin 90 moves forwardly in the slot 80 of the stationary member 70, and the moving washer 92 permits forward movement of the spring biassed plate 40 to a location with the bevelled edge 46 located adjacent the needle plate 20.At this time, the second end 52 of first slot 48 strikes the screw 73 of the stationary member 70 and the second end 64 of third slot 60 strikes the screw 75 of stationary member 70, thus preventing further forward movement of the plate 40 past the needle plate 20. However, with reference to Figs. 6, 7 and 10, the cylinder 88 continues to drive the retaining member 84, thus moving the retained nipper 42 and guide 44 above the needle plate 20, while the pin 90 leaves the second end 58 of the second slot 54, since the plate 40 is no longer free to move forwardly past the needle plate 20.

In this configuration of the gripping apparatus 16, the severed chain 18 is first moved to one side of the needle by a first blower nozzle 130, as shown in Fig.10, and is then moved by the second blower nozzle 14 into the space 112 between the nipper 42 and guide 44, with the curved guide 44 directing the chain 18 into the space 112, as shown in Fig.ll.

At this time, the cylinder 88 begins to retract the nipper 42 and guide 44 until the forward end of the nipper 42 is located adjacent the forward end of the plate 40 at the level of the needle plate 20. The severed chain 18 thus becomes caught between the finger 108 of the nipper 42 and the forward portion of the plate 40. Also, at this time, the washer 92 again engages against the second end 58 of second slot 54, and further retraction of the retaining member 84 also causes retraction of the plate 40 along with the nipper 42 and guide 44.

As previously discussed, when the guide 44 leaves the cam 82, the outer end 114 of the guide 44 is biassed against the nipper 42 to apply an increased bias to the nipper 42 against the plate 40 in order to draw the chain 18 taut as the nipper 42 and guide 44 move beneath the needle plate 20.

The cylinder continues to retract the nipper 42 and guide 44 beneath the needle plate 20, while driving the plate 40 through pin 90 to the configuration shown in Fig.12 with the gripping apparatus 16 beneath the needle plate 20, with the chain 18 located in a groove 116 between the needle plate 20 and a conventional fabric cutter 118, and with the plate 40 striking the stop 78. At this time, the guide 44 engages the cam 82, and the end 114 of guide 44 becomes disengaged from the nipper 42 to provide a lessened bias between the nipper 42 and the plate 40. Although the chain 18 is drawn taut beneath the top of the needle plate 20, the lessened bias of the nipper 42 permits easy removal of the chain 18 from the nipper 42 and plate 40 to prevent distortion of the first few stitches of the next sewn fabric. As previously discussed, the chain 18 is released from the gripping apparatus as the next fabric is sewn over the chain resulting in the sewn fabric of Fig.13.

The foregoing detailed description is given for clearness of understanding only, and no limitations should be understood therefrom.

Claims

1. An apparatus for cutting and positioning a chain of stitches for stitching onto material in a sewing machine having a needle and a needle plate, comprising: means for cutting the chain of stitches; means for positiining the severed chain in advance of the needle; a nipper having an outwardly directed finger; means for moving the nipper between a first position with the finger located beneath the needle plate and a second position with the finger located above the needle plate; a plate having a forwardly directed end; and means for moving the plate between a first position with the end located beneath the needle plate, and a second position with the end located adjacent the needle plate, said finger catching the severed chain and drawing it to a position between the finger and plate to releasably grasp the chain.

2. Apparatus as claimed in claim 1, further comprising means for applying a force between the nipper and plate.

3. Apparatus as claimed in claim 2, wherein the nipper is resilient, and the force applying means comprises means for pressing the nipper towards the plate.

4. Apparatus as claimed in claim 1, further comprising means for applying a first larger force between the nipper and the plate when the chain is first grasped between the finger and plate, and for applying a second lesser force between the nipper and the plate when the chain is drawn beneath the needle plate.

5. An apparatus for cutting and positioning a chain of stitches for stitching onto material in a sewing machine having a needle and a needle plate, comprising: means for cutting the chain of stitches; means for positioning the severed chain in advance of the needle; means for grasping the chain with a first larger tension at a location adjacent the needle plate and a second lesser tension at a location beneath the needle plate.

6. An apparatus for cutting and positioning a chain of stitches for stitching onto material in a sewing machine having a needle and a needle plate, comprising: means for cutting the chain of stitches; means for positioning the severed chain forwardly of the needle; a nipper having an outwardly directed finger; means for moving the nipper between a first location beneath the needle plate and a second position above the needle plate; a guide forming a space between the guide and the finger to catch the severed chain; means for moving the guide together with the nipper between a first location beneath the needle plate and a second position above the needle plate; a plate adjacent the nipper to releasably grasp the severed chain between the finger and plate; and means for moving the plate between a first location beneath the needle plate and a second position adjacent the needle plate.

7. Apparatus as claimed in claim 6, further comprising means for biassing the nipper towards the plate.

8. Apparatus as claimed in claim 7, further comprising means for biassing the guide against the nipper towards the plate when the finger is located adjacent the needle plate and for releasing the guide bias when the nipper finger is located beneath the needle plate.

9. Apparatus as claimed in claim 8, wherein the nipper has a shank connected to the finger, and in which the guide has a curved end portion with an end located above the shank.

10. Apparatus as claimed in claim 9, wherein the guide is resilient and normally bears against the nipper shank, and in which the guide biassing and releasing means comprises a cam disposed to lift the guide from the shank when the guide and nipper are located at the first locations beneath the needle plate and release the guide for engagement against the shank when the nipper and guide are located above said first locations.

11. Apparatus as claimed in any of claims 7 to 10, further comprising means for adjusting the bias of the nipper towards the plate.

12. Apparatus as claimed in claim 11, wherein the adjusting means comprises a screw bearing with an adjustable force on the nipper.

13. An apparatus for cutting and positioning a chain of stitches for stitching onto material in a sewing machine having a needle and a needle plate, comprising: means for cutting the chain of stitches; means for positioning the severed chain in advance of the needle; an elongated nipper having an outwardly directed finger; an elongated guide having a forwardly directed end portion defining a space between the finger and end portion; an elongated plate having a forward end located adjacent the nipper finger on a side of the nipper opposite the guide; means for moving the nipper, guide, and plate together from a location beneath the needle plate to a location with the finger and forward end of the plate being located adjacent the needle plate; means for stopping motion of the plate with the forward end located adjacent the needle plate;; means for moving the nipper and guide together above the needle plate to catch the severed chain in the space; means for moving the nipper and guide together to a location with the finger adjacent the needle plate to releasably grasp the captured chain between the finger and plate; and means for moving the nipper, guide, and plate together to a location beneath the needle plate to make the chain taut and releasably retain it in position for sewing onto a subsequent material to be sewn.

14. Apparatus as claimed in claim 13, wherein the end portion of the guide is curved.

15. Apparatus as claimed in claim 13 or 14, wherein the severed chain is located in a groove between the needle plate and a fabric cutter.

16. An apparatus for cutting and positioning a chain of stitches, constructed and adapted to operate substantially as herein described with reference to and as illustrated in Figs. 6 to 12 of the acompanying drawings.