Patent GB-887719-A (GB)
Title: Improvements in or relating to zig-zag sewing machines
IPC: D05B19/00
Filed: 1958-02-04
Abstract: 887,719. Sewing machines. GEGAUF AKTIENGESELLSCHAFT BERNINA-NAHMASCHINENFABRIK, FRITZ. Feb. 4, 1958 [Feb. 6, 1957; June 17, 1957], No. 3638/58 Class 112 In a zig zag sewing machine having separate means for adjusting the stitch width, stitch position and stitch length and adapted, for the production of buttonholes, to be operated simultaneously on the operation of the stitch width adjustment, the stitch length adjusting means comprises a member mounted on a lever so as to be movable to an operative position in which it is engaged by a second member, and the stitch width adjusting means comprises a lever which is movable into engagement with the second member so that the two levers can be moved simultaneously. The levers for controlling the stitch width, stitch position and work feed respectively are so arranged that when the levers are placed in a first position the left hand side a, Fig. 22, of a buttonhole is sewn with reverse feed, whereupon the levers are moved to a second position and the upper barring stitches b are produced with forward feed. The stitch width lever is then returned to the first position to sew the right hand side c of the buttonhole, and finally the stitch width lever is moved to the second position to produce the bottom barring stitches d. In Figs. 1, 2, 3 the stitch width lever 2 carries a member 7 which is journalled on a shaft 3a and is formed with arms 8 and 12. Arm 8 controls the position of a slide 9 in an arcuate slot formed in a member 10 to govern the stitch width via a rod 11. The stitch position lever 3 is fixed to shaft 3a, and a member 3b also fixed to the latter, is connected by a link 3c to the pivotally mounted member 10, the inclination of which may thereby be changed to vary the stitch position. Member 3b is held in alternative positions I, II and III by a spring catch. The stitch length lever 4 is slidably and rotatably mounted on a rod 16 connected to a feed-adjusting member 17. A pin 20 on rod 16 enters an L-shaped notch 19 in lever 4, and the latter is formed with a lug 18 which may thereby be turned to and held in the raised position to support a bar 14 pivoted at 15. A bar 23 pivoted at 22 has a handle 24, whereby a hooked end 23a of bar 23 may be positioned over lever 4, so that when the latter is moved into engagement with hook 23a a certain rate of reverse feed is established. The left hand side of the buttonhole is sewn with the levers in the position shown, with lever 2 engaging an abutment 5 and lever 3 in the position I. To produce the upper barring stitches levers 2 and 3 are moved simultaneously respectively to engage an abutment 6 and to the position II. Arm 12 thereby simultaneously engages bar 4, and via the latter and lug 18 moves lever 4 to a position of forward feed. On completion of the upper barring, lever 2 is moved against stop 5 for sewing the right hand side of the buttonhole, and is finally moved against stop 6 to sew the bottom barring stitches. In Figs. 14, 16, 20 lever 2 has pivoted thereto at 32 a two-armed lever 30, 31, arm 30 being biased by a spring 38 against an arm 35 of a twoarmed lever 34, 35 pivoted at 36 on lever 2. Arm 34 carries a button 37 which, on being pressed, rocks arm 30 into a position to co-operate with the stops 5, 6 and also moves a nose 33 on arm 31 into an arcuate groove 39 formed in lever 3. At the completion of the left hand side of the buttonhole, lever 2 is moved to engage stop 6 and also automatically moves levers 3 and 4 via nose 33 and arm 12. When lever 2 is thereafter moved between stops 6 and 5, nose 33 moves freely in groove 39 without changing the position of lever 3. On completion of the bottom barring, button 37 is released, whereby lever 2 may be moved beyond stop 5 to a position of substantially zero zig zag, when an additional arm 26 on member 7 engages under a nose 27 on lug 18 to raise lever 4 to a position of substantially zero feed, in order to produce final lacking stitches e.