Patent GB-467055-A (GB)
Title: Improvements in or relating to button-hole sewing machines
IPC: D05B3/06
Filed: 1936-08-10
Abstract: 467,055. Sewing-machines. JACKSON, L. MELLERSH-. (International Button Hole Sewing Machine Co.) Aug. 10, 1936, No. 21992. [Class 112] A buttonhole-sewing machine has means permitting adjustment for sewing straight or eyed, flybarred or unbarred, long or short buttonholes. The invention is shown as applied to a turret type of machine in which the work is clamped by holders 26 on a bed 25, and the laterally vibrating needle 28, mounted in a turret 33, and loopers mounted in a turret 34, are traversed longitudinally of the work to stitch round the sides of the buttonhole. The amplitude of the stitching-head stroke, is determined by the shape of the cam groove 30 in the cam 24. The length of the buttonhole is determined by adjusting the under plate 7 by the nut 8 in a slot 8a to cause a cam bar 32 to actuate the usual stop mechanism 29 at a suitable point in the stitching head stroke. The lateral feed-controlling or stitch-positioning mechanism usual in these machines is modified for ease of adjustment. The main cam 24 has on its lower face a second cam groove 35 with outer and inner concentric portions 35a, 35b connected by inclined portions 35c, 35d, Fig. 2. This groove receives a cam follower 36 carried by a lever 36 pivoted at 38 to the cam case 39. The lever has an arcuate slot 40 adjustably receiving a pin 41 by which it is pivoted to a link 42. The opposite end of the link 42 is connected at 45 to an arm 46 fast on a vertical rock-shaft 47 journalled in a bracket 48 carried by the stitching head. A second arm 49 is secured to the rock-shaft and engages a block 50 swivelled on a slide 52. Pivoted on a stud 54 of the slide 52 is a cam member and lever 55 with two grooves 57 on its under side engaging two pins 58, 59 carried by a lever 60. The pins 58, 59 are formed with rack portions, Fig. 17, so that one or other of them is placed in engagement with its groove. The opposite end of the lever 60 is carried by a stud 63 which is swivelled in a bearing in a bracket 15 on the cam case forming part of the stitching head. Intermediate its ends, the lever 60 is pivoted on a yoke 64, Fig. 18, with arms guided in slots in the edges of the bridge 62. The pivot comprises a bushing in a pin 67 and by tightening the nut 69, the yoke 64, bushing and pin 67 are clamped in desired position longitudinally of the lever. The amplitude of the longitudinal movement of the slide 52 and member 55 is determined by the position of the pin 41 in the slot 40. The parts are so designed that with the pin 41 at the innermost end of the slot 40, the pin 59 will traverse at least the full length of the sinuous part of the groove 57. Other adjustments cause the pin to traverse the straight end portions to a greater or less, but equal extent. Since the longitudinal movement of the member 55 takes place during a definite angular movement of the main feed cam 24, its speed of travel will be greater when the parts are adjusted to produce a relatively long movement than a short movement, and the period required for the pin 59 to traverse this sinuous portion of the groove 57 will be smaller in the former case than in the latter. The lever 55 has a stud 70, Fig. 1a, projecting through an opening 71 in the slide 52 and engages a groove 72 in a slide 73 mounted on the top of the bridge 62. At a point about midway in the length of the groove 72, the slide 73 has a second slide 75 with a cam portion 76 and a shank 77 threaded to receive an adjusting nut 78 to enable the cam portion 76 to be fixed to project for a greater or less distance into the way 72. Mounted in a recess beneath the slide 75 is a third slide 81. Operation. The adjustment of the mechanism for forming a buttonhole such as illustrated in Fig. 4, is as follows. The plate 7 is clamped according to the length of the slit s, including the eye e, the stops 87 being correspondingly set by their connection with the plate 7 through the bar 93. The cam bar 32 is set by the clamp screw 6. The slide 75 is adjusted to cause the cam portion 76 to project into the groove 73. The pin 59 is engaged with the groove 57 and the pin 41 set in an outward position in the slot 40 so that the slide 52 and member 55 will be given a relatively long longitudinal movement. The fulcrum 67 of the lever 60 is adjusted into a forward position so that the amplitude of lateral movement of the stud 63 will be relatively small compared with that of the pin 59. The stops 87 are adjusted to permit of long free movement of the slide 73 in the bridge 62 corresponding to the movement of the slide 52 and member 55 on the stitching head. With the parts in this position, the machine is started in the usual manner and the stitching head 27 begins its rearward movement along the work. The first part of the movement is an idle one, the cam follower 36 being in the concentric portion 35a of the cam groove 35, so that the slide 52 and member 55 are held against longitudinal movement in the head, and the stud 70 moves idly in the forward portion of the groove 72 till it reaches the projecting cam 76. The spring- pressed slide 81 holds the stud 70 yieldingly against the forward inclined side 85a of this cam, Fig. 1a, so that as the rearward movement of the sewing head continues, the slide 73 is idly carried along with it so that its rear end engages a rear stop 87 arresting its free motion. The stud 70 then rides up the cam forcing aside the slide 81 and moving the stud 70 laterally to cause the member 55 to swing on its pivot 54, swinging the lever 60 and causing its forward end, through the stud 63, to swing the stitching head laterally about the axis of the longitudinal feed stud 31 and bring the stitching mechanism into laterally offset position to form the flybar stitches b. The stitching mechanism is then started by the stop mechanism 29 by the cam bar 32 to form these fly bar stitches, the stud 70 being guided in a rectilinear path between the straight edge 86 of the projection 76 and the edge of the slide 81. The edge 86 then runs down the inclined side 85b of the cam 76 and the stitching head is gradually turned laterally back to its original position to form the offset stitches c. As the longitudinal feed is continued, the member 55 is held against swinging. movement about its pivot by the stud 70 in the frame 72 and against longitudinal movement by the engagement of the follower 36 in the concentric portion 35a of the groove 35, to form the stitches a. As the end of this operation is approached, the follower 36 is engaged by the inclined portion 35c of the groove 35 and the slide 52 and member 55 move forwardly in the head. The head is then swung laterally above the stud 31, first in one direction and then in the other with semi-rotation of the turrets, to form the offset stitches d, the radial stitches f, and the offset stitches d<1>. The cam follower 36 then reaches the concentric portion 35b of the groove 35 to cause formation of the stitches a<1>. The offset stitches c and the completion of the flybar stitches b<1> follow. The machine parts revert to their original position and the machine is stopped by the device 29. Shorter flybars or no flybars are formed by resetting the clamp screw 6 in a relatively rearward position with relation to the index plate 7. Wider flybars are formed by adjusting the slide 75. Longer or shorter eyes are formed by adjusting the pin 41 in the slot 40.