Patent GB-437585-A (GB)
Title: Improvements in and relating to buttonhole sewing machines
IPC: D05B73/12
Filed: 1935-05-14
Abstract: 437,585. Sewing-machines. HUGHES, R. M., 72, Cannon Street, London.-(International Button Hole Sewing Machine Co. ; 502, Harrison Avenue, Boston, U.S.A.) May 14, 1935, No. 14119. [Class 112] In a machine for sewing buttonholes of the " fly-bar " type, the barring cam has complete control of the side shaft movements of the stitch-forming mechanism during the whole of the cycle except when sewing round the eye end of the buttonhole. The side shift movements round the eye end are produced by an eye-forming cam. When the machine is started, the stitch frame 13 is moved to the right, Fig. 1, from buttonhole-cutting to stitching position and as it reaches stitching position the roll 69, Fig. 10, is carried up the cam face 68, rocking the lever 70 and releasing the dog 125 to clutch the pulley 123 to the shaft 25 to set the stitchforming mechanism in operation. The main cam 20 has the usual eye-forming groove as its under face by which the stitch frame is given a lateral swinging movement while sewing round the eye of the buttonhole. This groove co-operates with the follower 27 carried by the lever 28 on the rock shaft 29. This rock shaft carries another arm 31 with a block secured in a groove in the under side of the frame 9. The swinging movement of the arm 28 produced by the cam groove gives a swinging movement frame about its pivot 24. The means for giving the lateral movement to the stitch frame which differentiates the barring stitches from the side stitches of the buttonhole comprises a barring cam element 34 mounted on the frame 9 and confined between two members 35. This cam is provided with two grooves 37, 38 co-operating with followers 39, 40 mounted in and vertically movable through a block 41 which is secured to the extension 42 of the frame, this extension having an opening through which the pins operate. The pins 39, 40 are connected together by a link to move in unison but oppositely so that when one pin is in operative engagement with its barring cam groove, the other is raised out of engagement with the other groove. The barring cam groove 37 has a straight part 55, an offset part 56 and a second straight portion 155. The cam groove 38 is similar, but with an oppositely arranged offset part 58. When the machine comes to rest, the pin 39 is depressed and occupies the straight portion 55 of the groove 37. This positions the stitch frame so that the stitch-forming mechanism is in the same position laterally which it occupies for making the side stitches 3. When the machine is started, the movement of the stitch frame shifts the pin 39 longitudinally of the straight part 55 of the slot 37 to bring it to the offset part 56. During this time the follower 60 on the arm 59 of the block 41 is travelling in the straight slot 61 and the lateral movement of the pin 39 causes the block 41 to swing laterally about the follower 60 to shift the rear end of the frame 13 to bring the stitchforming mechanism in the line of the buttonhole slit. The stitch-forming mechanism then starts to lay the first barring stitches 6 while the pin 39 is travelling in the groove 56. When the pin 39 strikes the cam face 62, the block 41 is shifted laterally to shift the stitch frame to swing its front end to form the side stitches 3. As the feeding movement of the frame 13 continues, the pin 39 passes out of the cam portion 56 into the straight portion 155, the side stitches 3 being formed during the travel. While these stitches 3 are being formed, the pin 39 is gradually withdrawn from the groove 37 and the pin 40 gradually depressed into the straight part 57 of the groove 38 to sew the other side of the buttonhole.