Patent GB-1304044-A (GB)
IPC: D05B19/00
Filed: 1970-03-19
Abstract: 1304044 Zig zag sewing machine FRITZ GEGAUF AG BERNINA-NAHMASCHINENFABRIK 19 March 1970 [21 March 1969] 13420/70 Heading D1G A zig-zag sewing machine having elements for regulating the stitch-width, -field and -length, and retaining means for the stitchwidth and field settings has a manually operable switching element controlling the regulating elements and movable from an inoperative rest position into successive control positions each corresponding to a respective segment of a closed pattern to be sewn, the arrangement being such that when the switching element moves from the inoperative to the first control system the regulating elements are automatically changed into the starting position for sewing the pattern and the retaining means are rendered ineffective. Stitch length and direction is selected by a position of a regulating block 35 pivotable against the action of spring 47 by movement of a knob 9 on a screw threaded bolt 46. The selected position is held by screwing the knob and bolt into a hub 42 on block 35 until the knob 9 bears against the machine frame. The block presents a slideway 36 engaging a block 37 pivoted to a stitch length adjusting fork 39 embracing an eccentric 41 on the arm shaft 22. The stitch width operating element 5 is secured to a lever 14 by a tubular shaft 12 and presents an arm carrying a block 18 slidably engaged with a jaw 19 on a guide fork 20 provided with a block 22 guided an element 23 oscillated from the arm shaft by means not described and connected to the needle bar gate. Rotation of lever 14, which is provided with a position retaining spring 27, by knob 5 varies the stitch width.  The stitch field is manually set by an operating element 7 connected to a lever 25 by a shaft 24 within shaft 12. A link 30 connects the lever 25 with the zero point of regulation element 23. A position retaining spring 33 is provided for the lever 25.  Buttonholing. A switch element 10, which positions the controls for stitch-direction and -length, stitch-field and stitch-width, is connected to an element 51 provided with a detent spring 86 cooperating with six notches 84 to provide a six position switch, one position being an inoperative position, the other five corresponding to different segments of the buttonhole indicated by indicia (11, Fig. 1 not shown) on the machine frame. Element 51 is provided on opposing faces with cam grooves 53, 61 cooperating with transmission links 58, 62 respectively controlling the positions of levers 14 and 25 for setting the stitch-width and -field. A cam surface 81 at the periphery of the element 51 is followed by one end of a lever 79 pivoted at 78, the lever releasing the retaining springs 27, 33 from levers 14, 25 at all positions of the switch element 10 other than the inoperative position. A cam surface on a plate 71 rotating with the element 51 cooperates with a transmission lever 72 which abuts beneath bolt 46 to move the feed regulating block 35 into its required positions against the action of spring 47. Movement. of element 10 through its five operative positions in turn results in the sewing of the successive segments of the buttonhole. The element 51 may be of sintered material or of plastics material.