GB255708A - Improvements in and relating to thread trimming devices for sewing machines - Google Patents

Abstract

255,708. Hughes, R. M., (Reece Button Hole Machine Co.). Dec. 3, 1925. Thread-cutters and thread-end holders. -In group-stitching machines having thread-holding and cutting devices which grip the thread at the end of a stitching period and cut the thread both at the end of this period and at the beginning of the next, the threadholder is actuated by the relative movment between the stitchforming mechanism and the work-holder and the cutter by a cam associated with the main cam, or both the threadholder and the cutter are actuated by rockshafts extending through the bed-plate and actuated by levers controlled by a cam associated with the main cam. The thread-holding and cutting devices are carried by the work-holding means and comprise a thread-gripper 9 having a hook 11 and pivoted to the clamp plate 2 and co-operating with a plate 12. Just before the completion of the stitching the arm 9 is moved across the stitching line, and after the completion is swung back to engage the needle thread and draw it on one side, clamping it against the plate 12. The thread-cutter blade 16 is mounted on an arm 17 acted on by a spring 19 and is actuated by means comprising. an arm 21 mounted on a shaft 20 having a second arm 24 engaged by a lever 26 actuated by a cam 30 on the shaft of the main cam 7. The cam 30 is provided with two notches 33, 34 into which a projection 31 on the lever 26 enters at the times when the thread is to be cut, thus allowing the lever 26 to be moved under the influence of a spring 32 actuate the arm 21 and lever 17. The thread-holding device when actuated by the relative movement of the sewing-head and the workholder, as shown in Figs. 1 - - 3, has an extension 36 with a spring-pressed sleeve 37 carrying a foot 39 adapted to engage a projection 40 carried by the head. The foot is allowed to move freely when so engaged while the head is moving in one direction to stitch a buttonhole but when moving in the other direction a stop device couples the foot to the arm 9 and causes it to move to carry the arm across the stitch line. When the stitching mechanism comes to rest and the parts are further moved to buttonhole cutting position the projection 40 is moved away from the foot and allows the arm 9 to swing back under the action of its spring to the position shown in Fig. 3, thereby nipping the thread In the modification shown in Fig. 7. the arm 9 is moved by an arm 44 on a rock-shaft 45 actuated by a lever controlled similarly to the lever 26 by a cam on the main cam shaft. A cutter for the under thread is also described and comprises parts 55, 56 carried by blocks 57, 58 pivoted at 59 and having arms 60, 61 beween which is a cam member 63 mounted on a shaft 64 from which extends a lever 65. The lever 65 is engaged by a spring- stressed lever 69 which is actuated by an arm 72 projecting from the hub 29 of the main cam.