| 摘要 |
995, 274. Sewing machines; work-holders. A.B.TRONICS Inc. July 5, 1961 [Sept. 22, 1960], No.24255/61. Heading D1G. In a sewing machine a suction-exerting duct is so disposed as to draw the stitch chain between work pieces into means adapted to sever the chain. In arrangement Fig 3, for closing the transverse opening in the foot of a circularly-knit men's hose, needles 44 co-operate with an upper looper 46 and a lower looper, not shown. A fixed cutting blade 62 is disposed at an acute angle to the line of feed effected by a feed dog 50. A co-operating movable blade 64, pivoted at 86 to blade 62 and biased thereagainst by a spring 106, has a finger 102 embraced by the forked end of a bar 66 fixed at its other end to the feed bar 94 actuated by an eccentric 92 on a rotary shaft 90. A duct 68 has an open end disposed adjacent the blades 62, 64. A duct 70 discharges compressed air into duct 68 in a direction away from the open ends so as to create a suction at the latter. The work on leaving the stitching point is directed off the line of feed by an upwardly arched work guide and the stitch chain between successive workpieces is drawn between the blades 62, 64 by the suction at the open end of duct 68. The seam closing the longitudinal opening in the foot of a circularly-knitted women's hose is produced automatically by mounting a workpiece in a pivoted work holder comprising a pair of plates 132, 134, Fig. 6, hinged together at 136. Curved edges 138, 140 of said plates are concentric with a pivot pin 142 which depends from plate 132 into engagement with a fixed pivot post 144. The seam is thereby formed parallel to the edges 138, 140. Owing to the limited movement of the work holder, the thread chain at the completion of the seam will be directed away from the blades 62, 64, and more suction will therefore be needed to draw the thread chain therebetween at the end of the seam than at the beginning. The arrangement automatically provides the addition suction. An air pressure, line 154 is connected to a line 122, supplying duct 70, through a constricted passage 156 which by-passes a main passage 148, 152 normally closed by a magnetically-controlled valve 150. Towards the end of the seam, a cam projection 172 on plate 132 engages the actuating arm 170 of a micro switch 160 to effect the opening of valve 150. |
