Patent GB-874900-A (GB)
Title: Rotary take-up for sewing machines
IPC: D05B51/00
Filed: 1959-02-16
Abstract: 874,900. Sewing machines. SINGER MANUFACTURING CO. Feb. 16, 1959 [March 21, 1958], No. 5231/59. Class 112. A rotary take-up member for sewing machines, which acts on a needle thread extending between a pair of thread guides and is continuously rotatable in one direction comprises a base portion 28 and an arm 40 extending outwardly with respect to the axis of rotation, the arm having a leading edge 60 and a trailing edge 70, concave outer thread confining throats 62, 72, concave inner thread confining throats 61, 71, a convex thread detaining means 64 on the inner half of the leading edge 60 between the inner and outer throats 61, 62, and convex thread detaining means 74 on the outer half of the trailing edge 70 between the inner and outer throats 71, 72. In Figs. 1 and 2 the main shaft 13 of the sewing machine drives the needle bar 18 through a driving link 16 and crank pin 15. The extremity 23 of the crank pin 15 (Fig. 6) is formed with a raised arcuate rib 24, fitting into an arcuate slot 27 of a circular plate 25 which carries a counterweight 26 and which is clamped in position by the base portion 28 of the take-up member. The head 10 of the sewing machine is closed by a flat plate 30 which is formed with a circular opening 32 to accommodate the plate 25 and which supports a take-up guard 35 forming with cover plate 30 a thread receiving slot 36. Ears 41 and 42 on the base member at its junction with the arm 40 are turned inwardly to enter respectively an aperture 43 and a notch 44 in the plate 25; to prevent the thread from being wedged between the base portion 28 and the plate 25. The ears 41, 42, with the arm 40 define the inner thread confining throats 61, 71. At its outer extremity the arm 40 is bent slightly towards the cover plate 30 and terminates in a thread retainer 45 bent away from the plate 30 and formed with fingers 46 and 47 to prevent the needle thread from falling off the arm 40. The fingers 46, 47 with the arm 40 define the outer thread confining throats 62, 72. The needle thread extends in a single loop around the arm 40 and the take-up action is derived as the thread travels back and forth along the arm 40, during rotation of the take-up. Should the needle thread break a knife blade 81 on the take-up guard 35 severs the loose end of thread thrown out by centrifugal force to prevent the thread winding on the take-up arm. A further knife 80 on the cover plate 30 severs any abnormal wind up of thread on the arm 40. As illustrated in Fig. 1 the needle loop has been shed by the loop taker 20 and the arm 40, by rotating, has started to take-up this loop to set the stitch. In doing so, the thread slides along the leading edge 60 of arm 40 until it reaches the convex shoulder 64 which retains control of the thread after stitch setting so as to provide a controlled slackening of the thread until after needle penetration has occurred. The thread loop then drops off the shoulder 64 but is confined by the throat 61 which allows the necessary slack thread needed by the loop taker. As the arm 40 descends, the thread moves from the throat 71 along the trailing edge 70 of the arm 40 which serves to retain the thread loop on the take-up arm as the loop is paid out by the take-up, until the loop finally falls off convex shoulder 74 at which time the take-up cycle begins again. Specification 813,364 is referred to.