Patent GB-190910828-A (GB)
Title: Thread Cutting Devices for Sewing Machines.
Inventor: FAIRWEATHER WALLACE
IPC: D05B65/00
Filed: 1909-05-07
Granted: 1910-05-05
Abstract: 10,828. Fairweather, W., [Singer Manufacturing Co ]. May 7. Button-attaching machines; thread-cutters; thread-end holders.-The needle -and under threads are cut and their ends secured at the close of a stitching operation, and after the commencement of the next stitching operation the part of the free end of the needle thread not drawn into the stitching is cut off. The devices are shown applied to a button-attaching machine in which the upper work-clamp member 14 is attached to the presser bar 5 and can be lifted by a treadle lever 24. During the rising of the needle and when the take-up is at about the middle of its stroke in the formation of the last stitch, a finger 68, Figs. 3 and 11, is moved by cam mechanism into the path of the needle and enters the needle-thread loop. The finger 68 is fixed to a slide 65 and is operated from a cam 50 through a lever 76 and link 73. The continued upward movement of the take-up tightens the loop about the finger, and the thread is cut by the sharpened edge 68'. At this stage the machine is brought. to rest. In opening the work clamp, a finger 97, which is linked by the rod 90 to a depending arm 88 of the treadle lever, is swung underneath the work across the needle hole. It engages the under thread and pressing it against the edge of a knife 100 severs it. The finger passes beyond the cut thread-end, and, on its return journey, when the clamp is closed for the next operation, engages the thread again and carries the end over the needle hole and under the centre of the forked button-plate 18, between which and the throat plate it is retained. The opening of the work-clamp also swings a thread finger 115 across the needle path. It carries the needle thread with it and holds it against the lug 116, upon the upper member of the clamp, until the clamp is closed. This finger is carried by a plate 103 pivoted on the presser bar and an arm 107 on the plate passes loosely through a slot in a fixed plate 112. A spring holds the arm unyieldingly against the bottom of the slot and permits the finger to yield if it contacts with the needle thread before it is cut. In the next operation of the machine after the clamp is closed, the first descent of the needle is through a hole 143 in the finger 68. During the upward movement of the needle, the finger 68 withdraws, hrst nipping the needle threadend between itself and the underside of the supporting bracket 119, and afterwards, in the continued operation of the machine, forcing it against the cutting-blade 120 where the free unused thread end is cut off. To ensure that the needle thread is not pulled through the needle eye after it is cut, a small thread-tension 122 is carried by the needle bar near the needle, and a finger 134 is provided to pull off a supply of thread when the work clamp is opened. This thread finger engages the thread between two thread-guides 130, 137, and is operated by a lever 125. The latter is pivoted at 126 moved by a pin 130 on the presser-bar to cause the end 131 to separate the tension plate 132. An arm 138 on the lever contacts with the thread finger. In sewing two-holed buttons the button-clamp is not moved, the needle bar being vibrated. In sewing four-holed buttons, after one pair of holes has sewn through the clamp is moved to bring the second pair of holes into line with the needle. For this purpose, an arm 41, Fig. 3, is adjusted on a clamp-operating shaft 31 so that when a cam 80 rocks the lever 42, 47 the shaft 31 will be oscillated and the clamp moved. The cam 80 is secured by screws to the underside of the cam 50.