GB1218518A - Round end buttonhole mechanism for zigzag sewing machines - Google Patents

Abstract

1,218,518. Sewing-machines. SINGER CO. 16 June, 1969 [21 June, 1968], No. 30366/69. Heading DIG. A zig-zag sewing machine comprises a buttonhole mechanism for producing buttonholes having round ends by varying the field of the sewing needle and the direction of feed in such a way that the direction of feed is gradually reversed at each end of the button-hole as the field is moved gradually from one side of the button hole to the other. As shown in fig. 2 the needle bar 23 is mounted in a laterally pivotable support gate 27 which support is moved by a link 29 driven by a wobble plate by levers 36, 38 which in turn are selectively engagable with and driven by a stack of cams 42. The field of the needle is varied by a pin 52 on the link 29 which can engage any one of these surfaces 46, 47 or 48. A stitch regulator is provided comprising a pivoted member 85 with a block 83 fastened to the feed dog drive arm 82 in the normal way. A cam 111 is provided with ratchet teeth 113, 114 over part of its surface and is driven by a pawl from a reciprocating part of the machine. The arrangement is such that in the spaces between the ratchet teeth the cam can be manually turned. The cam operates through a follower 126 and a single operating member 124 to move the stitch regulating mechanism. For one set of teeth the movement is such that the stitch regulating mechanism is moved from, for example, a forward direction and a neutral position and subsequently to a reverse direction and for the other set of ratchet teeth the opposite sequence is produced. A link 133 is also influenced by this movement to act through a lever 162 a bar 163 and a lever 167 to move the lever 38 and hence alter the field of the needle. To form a button hole the lever 38, is set against the smallest surface 48 and the cam 111 is driven to reverse the feed direction while the lever 38 is moved away from the surface 48 thus producing the the round end of the buttonhole. The cam is then turned by the operator so that it is not driven and the sewing machine sews a series of zig zag stitches, with the field in its shifted position, down one side of the button hole. The cam is then turned by the operator so that the other set of teeth are engaged by the pawl and the field and stitch direction are returned to their original settings thus forming the second round end of the buttonhole. The cam is then again turned by the operator and the second side of the button hole is formed in the opposite direction to the first side again as a straight line of zig zag stitches. The single operating member 124 is connected to the stitch regulator by a pin 129 which pin can be engaged or disengaged by movement of a lever 141 so that the machine can be used as a normal zig zag machine when buttonholing is not required.