Patent GB-190808125-A (GB)
Title: Thread Cutting Device for Sewing Machines.
Inventor: FAIRWEATHER WALLACE
Filed: 1908-04-13
Granted: 1908-09-03
Abstract: 8125. Fairweather, W., [Singer Manufacturing Co.]. April 13. Button - attaching machines ; t h r e a d cutters and end holders; govrrning needle thread ; slopping, automatic. - Relates to threadcutters and threadend holders, which are shown applied to a button-attaching machine described in Specification No. 4051, A.D. 1904. T h e thread - nipping members are situated below the throat plate, and comprises a threadengaging blade 61 a n d two spring blades 60, 62 above and below the blade 61, all of which are independently pivoted upon a pin 64 on which a bar 65, which extends to the rear of the :nachine and is reciprocated by a cam-actuated lever. The blades 60, 62 have fingers 91, 87 which engage a recess 79 in one of the fixed cam-plates 75, 76, and the blades 60, 61 have cam-surfaces 77, 78, and by these means the requisite moveTents of the fingers are produced. The three pieces are held so that spring plates 89, 86 press upon a finger 81 by a bridge-piece 76<1> below them. The thread-cutter 95, which cuts by co-operation with the upper surface of the p'ate 89, is carried by a slide 98, Fig. 1, and reciprocated by means of a bar 100 and a lever 102 which engages with a tail-piece 107 fixed to the stopping-lever 108, and so receives movement when the part 110 comes in contact with the edge of the cam 111 positively to stop the machine. A thread clamp 120 is attached to the needle-bar and is closed first to tension and afterwards to clamp the thread by means of a lever 124, pivoted to the needle-bar, when that lever is actuated by a plate 125 on a pushrod d 126. To the end of the push-rod, a spring plate 137 is secured by means of a screw 139, the plate 137 being also secured to the machine head by a screw 138. When the rod 126 is moved forward, the plate 137 acts as a detent to hold the slackcontrolling spring 136 in its inoperative position, as shown in Fig. 5. The other parts of the machine are similar to those des ribed in the abovementioned Specification. The button clamp is moved laterally by a cam-lever 36, which is linked by a sliding block 40 to a pillar 34 on the clamp plate 30 and is moved to and from the operator by a cam-operated yoke-lever 47, Fig. 10, which carries a pin 46 engaging with a sliding-rocking cylinder 45 mounted in a block 31 attached to the c'amp plate. Figs. 11 and 19 show the thread cutter and end holders in the position occupied at the commencement of a cycle of operations. The end of the shuttle-threads a is nipped between the spring blade 86, and the thread-engaging finger 81 in the extreme forward and lateral positions of the threadnipping members. The machine is set in motion by an angle-lever 140 by means of a treadle-rod, by which the stop-lever 108 is thrown forward' and engaged by the tripping-lever 112 to withdraw the plunger-rod 110 from the cam 111 and shift the belt from the loose to the fast pulley. In its first descent, the needle 16 carries its thread b through an eye of the button c and the fabric and also through the needle-hole 90 in the nipping-plate 89. The cam wheel 39 moves the rod 126 to the extreme forward position and thereby presses the tension plate 120 firmly up in the needle-thread, whereby the action of the shuttle is merely to draw down the cut end of the needle thread through the needle-hole 90, as represented in Fig, 20, without drawing the usual stitch-length of thread through the primary tension-device 132. As the needle rises to its highest position, the lateral retraction of the finger 81 of the lever 61, by engagement of its projection 83 with the stationary cam-projection 78, operates to grip the needle thread end between the members 81, 89, as represented in Fig. 21, preparatory to the production of the initial button-fastening stitch. The cut ends of both needle and shuttle threads are then held as they would have been if attached to the work after a series of stitches had been made, and are so held during one or more fastening stitches, after which the thread-nipping members are retracted into the inoperative position, and the lateral fingers 87, 91 at the same time engage the adjacent end of the cam notch 79 and laterally move the blades 86. 89, so as to release both thread-ends. At the completion of the stitching operation, the lever 112 is tripped by one of the lugs 114, and the stop-lever 108 returns to its initial position, throwing the end of the plunger rod 110 beneath the lower portion of the cam 111 and moving the belt from the fast to the loose pulley. In the continned operation of the machine due to the momentum of its moving parts, the thread-nipping levers 60, 61, 62 are advanced just as the needle is rising from delivering its thread-loop to the shuttle 17. The loop is carried by the shuttle towards the front of the machine and over the point of a notched loop-dividing plate 142 secured upon the top of the shuttle race, and the loop is subsequently entered by the still advancing threadengaging finger 81. The shuttle-thread meantime is engaged by the rearward edge of the finger 81 and is subsequently clamped by the hooked nipping- blade 86 as it is moved laterally by the engagement of the lateral finger 87 with the end of the camnotch 79. Simultaneously with the advance of the thread-nipping members, the rod 126 is partly withdrawn, so that the tension-plate 120 is only lightly pressed upon the needle thread, and the shouldered end of the detent plate 137 is moved to detain the spring 136 as the take-up lever draws the needle thread taut and raises the spring 136. As the upper end of the plunger rod 110 snaps into its notch in the stop-cam 111, the remaining momentum of the moving parts causes the lateral throw of the stop-lever 108 to advance the knife 95 across the forked end of the blade 89, within which the shuttle thread and the limb of the needle-thread loop connected with the work are confined, so as to sever both ends, the take-up lever rising at this time to its highest position to maintain the needle thread taut for the cutting operation.