Patent GB-549425-A (GB)
Title: Buttonhole sewing machine
IPC: D05B3/08
Filed: 1941-09-06
Abstract: 549,425. Sewing-machines. FAIRWEATHER, W. C. (Singer Manufacturing Co.). Sept. 6, 1941, No. 11419. [Class 112] Buttonhole sewing machines.- The position of the barring section on the pattern cam is not adjustable and suits the longest buttonhole. For shorter buttonholes, when the stitching of the second side is complete the connection between the longitudinal feed cam and the slide frame is uncoupled, the slide frame is locked in position and the pattern and feed cams are turned idly by the rapid feed gear to the barring position. The stitching shaft is then restarted for the barring stitches and afterwards the rapid feed gear turns the cams to the finalorbuttonholecuttingposition, the slide frame is unlocked and a cam-operated lever pushes it on to its final position where it is recoupled to the longitudinal feed mechanism. The barring stitches are made at right angles to the side stitches and for this, the turret is turned through 90 degrees. The locking of the feed frame, prior to the barring stitching gives a retrograde movement to the frame to cause the barring stitches to overlap the side stitches. For the side stitching, the pattern cam moves the stop-motion lever far enough to permit a latch to engage and hold it and the latch is afterwards tripped. For the barring stitches, the stop motion lever is not moved far enough to be held by the latch and the stitching shaft is stopped by the passing of the barring section off the cam. For eyeless buttonholes, the stitching is stopped during the rotation of the stitching instrumentalities. The means for moving the clamp laterally during the stitching of an eyed-end is rendered inoperative and the clamp is locked against lateral movement. The body of the pattern cam, Fig. 23, in which is cut the groove 73 for giving lateral movement ot the work, carries two discs 91, 92 the former having the stitch-starting cam 103 and the latter, the stitchstopping cam 60. The discs are adjustable equally and in opposite directions by means of gears and a knurled head 98. A second stitch-starting cam 111 is fixed, with small adjustment, upon the cam body and is operative to start the stitching of the second side of eyeless buttonholes. The stitch starting and stopping cams 117, 118, Fig. 7, for the barring stitches are in a fixed position on the cam body but the length of the combined cams is adjustable to vary the number of the barring stitches. The walls of the cam groove 73 are cut down at 84 in the region controlling the lateral movement in the formation of an eyelet end but are normally effective since the follower pin rides on the floor of the groove. For stitching an eyeless buttonhole, the follower pin is raised above the cut-down walls 84 and the cam is therefore inoperative in this region. For this purpose the follower pin 74, Fig. 7, has a cross-pin riding in a bayonet slot and fitted with a knurled head 81. The upper end of the follower pin has a cross slot which is entered bv a short rid on the slide frame during the turning of the eyeless end. Longitudinal feed is transmitted to the slide frame 38, Fig. 7, from the cam-lever 40 by the parts shown separated in Fig. 11. A rod 45, pivoted at 46 to a bracket 48 secured on the underside of the slide-frame rides in a bore 451 in a block 42 pivoted to the cam lever 40. A spring about a spindle 49 presses a nose 50 on to the surface of the rod 45. When the nose enters a notch 51, a locking arm 52 on the spindle 49 passes behind a lug 53 and locks the parts together. The parts are uncoupled when a third arm 54 is moved by an arm 55, of a three-armed lever 55, 58, 59 as the arm 59 rides up the stitch-stopping cam 60. The stop-lever is held during the side stitching by a latch 61 which is released by the arm 58. Actuation of the three-armed lever also presses a tooth 71 on a spring arm 70 into'engagement with one of the teeth 69 on a bar 68 attached to the slide-frame. The tooth 71 is bevelled on the left side and in engaging a tooth 69 presses the bar 68 and slide frame backwards. When the rapid feed has completed the movement of the feed cams to the initial position, during which time the slide frame has remained uncoupled from the cam-lever 40 and locked by the tooth 71, the arm 59 rides off its cam removing the tooth 71 and releasing the latch 54, 52, and a cam-lever 128 pushes the slide frame to the initial position where it is coupled again to the camlever 40. For this purpose, the cover plate 93 of the pattern cam carries a non-adjustable part 108 which forms a continuation of the adjustable stitch stopping cam 60. When the stitching is to be stopped for the turning of an eyeless buttonhole, a pin 110 on the bar 68 is moved to the dotted line position. In the travel of the slide-frame the pin 110 engages the bowl 671 and removes the latch 61.