Patent GB-356371-A (GB)
Title: Improvements in and relating to sewing machines
IPC: D05B3/08
Filed: 1930-07-07
Abstract: 356,371. Buttonhole sewing-machines. HUGHES, R. M., 72, Cannon Street, London.-(International Button Hole Sewing Machine Co. ; 502, Harrison Avenue, Boston, U.S.A.) July 7, 1930, No. 20532. [Class 112.] In a machine for sewing tacks at the end of buttonholes, pocket corners, &c., and having a work-clamp movable in two different directions to form a series of long underlying stitches and a series of short overlying stitches, the two movements of the work clamp are derived from two axially aligned cams. Means are also provided whereby the length of the underlying stitches can be varied without changing the spacing of the overlying stitches. The tack formed in the work 1 by the sewing machine comprises the usual long under. lying stitches 2, Fig. 12, and the short overlying stitches 3 which extend the length of the long stitches. After the machine is started, it forms two or three short tying-in stitches 4 for anchoring the thread to the cloth. It then forms the long stitches 2 and the short stitches 3 in succession. The machine is provided with a main frame 5, a worksupporting arm 6, and an arm 7 supporting the needle bar 8. The needle 9 co-operates with the usual oscillating hook carried in the housing 10. The stitch-forming mechanism is operated from a driving shaft 11 geared to the needle shaft 12. The hook is operated by a shaft 14 connected to the shaft 12 through a crank and rod 15. The work 1 is held on a plate 23 by clamps 24 carried in a U-shaped frame member 25 slidably pivoted at 27 on the arm 6. The frame 25 has an extension 28 with a slot 29 working over the pin 27. When the frame 25 swings, the short stitches 3 are formed and when it slides, the long stitches 2 are formed. The two cams for effecting these movements are mounted on a vertical shaft 30 driven from the shaft 12 by gears 32. The combined long - stitch and feed cam 33 is loose on the shaft and the short stitch cam 34 is fast thereon. The cam 33 has a groove 35 in which works a follower 36 on the end of an arm 37 on the sleeve 38 which is loosely mounted on a vertical post 39. The sleeve carries a slotted arm 40 connected to the work clamp frame 25 through a lever 41 which is pivoted to the work arm 6 at 42 and connected to the arm 40 by a screw 43. The lever 41 is connected to the work clamp frame 25 by a link 45. The rocking movement of the arm 37 is produced by the cam groove 35 and causes the lever 41 to turn about its pivot 42 to impart a swinging movement to the work clamp frame 25. The work clamp is given its longitudinal movement for forming the short stitches by a cam groove 46 in the under side of the cam 34 in which operate a follower on an arm 47 pivoted on the post 39. This arm is connected to a member 48 by a link 49 which is pivoted to a stud 50 depending from the frame 25 and operating in a slot in the arm 6. The arm 48 is disconnected from the working member 47, during the sewing of the stitches 2, but is coupled thereto during the formation of the stitches 3. The length of the stitches 2 is varied by shifting the point of connection between the arm 40 and lever 41.