Patent GB-386539-A (GB)
Title: Needle-thread take-up mechanism for sewing machines
IPC: D05B51/00
Filed: 1932-06-14
Abstract: 386,539. Sewing-machines. FAIRWEATHER, W. C., 65, Chancery Lane, London.-(Singer Manufacturing Co. ; Elizabeth, New Jersey, U.S.A.) June 14, 1932, No. 16777. [Class 112.] A lock-stitch machine is provided with a link-and-crank needle-thread take-up adapted to carry a portion of the thread around a field, together with controlling elements arranged to assist the stitch-setting action and to control slack thread. The main shaft 5 carries a bushing 13 secured in the bracket-arm of the machine. The end of this shaft carries a counter-balanced crank-disc 14 apertured to receive a pin 15 carrying the boss 17 at one end of the take-up finger 18. This has the usual thread eye 19 at one end and pivots on the stud 21, enclosed by the boss 22 of a link 23. The end of this link is journalled on the reduced part of a pin 25 secured in the bracket-arm head 4. The take-up is actuated by the crank pin 15 to follow the path F, Fig. 7. Journalled on the boss 17 of the take-up member is the boss 26 of the needle-bar actuating-link 27, operated by the same pin 15. This link is connected to the needle-bar 31 by the bearing 30. A fixed thread-controlling element 46 is adjustably secured at its upper end on the take-up side of a guard-plate 47 extending in a plane parallel to the take-up field F. This plate is cut away at its lower end to provide an upwardly and rearwardly inclined threaddeflecting cam 49 terminating in a vertical ledge 50 spaced from the bracket-arm head 4 to provide a thread-clearance slot 51. A guide 52 is also provided to prevent the thread from engaging the front edge of the guard. The element 46 has a stitch-setting shoulder 53 in the path of a portion of the thread leading from the take-up eye to the needle, to assist the take-up finger in setting the stitches. The upper side of the shoulder 53 is inclined downwardly to provide a cast-off surface. The offset shank 55 of an auxiliary thread-detaining lip 56 extends forwardly from the head 4. The upper edge 57 of the lip is inclined to provide a ready cast-off for the thread. During the upstroke of the take-up finger, the thread T engages the inclined cam 49, Fig. 7, and is therefore deflected into the slot 51. The bending of the thread over the cam 49 assists the take-up in taking up rapidly the loop of thread cast off by the loop-taker. During the continued upstroke of the take-up, its action is further aided by the inclination of the finger 46 in a direction away from the plane of the field F. The rearward movement of the take-up eye 19, at the upper end of its stroke, bends the thread about the shoulder 53, so setting the stitches. At this time, the thread has been deflected by the cam 49 into the guide-slot 51 of the guardplate 47, the stitch-setting being completed just after the take-up eye has begun its downward movement. The thread remains in engagement with the shoulder 53 during the initial downward movement of the eye and until the needle enters the work, this position being shown in Fig. 7. The bending of the thread over the lip 56 prevents formation of slack in the thread leading to the needle until the beak of the loop-taker enters the thread loop formed as the needle commences to rise. The subsequent spreading of the loop pulls the thread from the lip 56, the downward inclination of the edge 57 permitting the thread to be given up freely.