Patent GB-179278-A (GB)
Title: Stitch-forming mechanism
IPC: D05B57/02
Filed: 1921-02-01
Abstract: 179,278. Fairweather, W., (Singer Manufacturing Co.). Feb. 1, 1921. Button-hole sewing machines; doubleloop stitching.-Relates to overseaming machines of the kind described in Specification 9460/12, wherein a laterally jogging needle co-operates with a threaded aud unthreaded looper and two loop spreaders or detainers for distending the thread loops and consists in mounting the detainers so that they act unassisted by the loopers. The detainers are pivoted on axes transverse to the paths of the needles, have beaks facing in the same direction and are simultaneously moved in opposite directions. The loopers are actuated through a pin and star wheel drive to produce periods of dwell in their motion and are movable in the plane of lateral movement of the needle. The non-threaded looper and a loop-detainer co-operate to present the needle-thread loop to the needle in a position above the looper. The looper mechanism is mounted in a rotary turret 47 which carries a post 50 in which is fulcrumed a carrier 51 for a threaded looper 53 and a non-threaded looper 54. The carrier 51 is connected by a link 58 to a sleeve 60 having a groove 61 engaged by a forked arm 62 secured on a rod 63 slidable in the frame and reciprocated by a link 65 connected to a pin 66 carried eccentrically by a shaft 68 having thereon a gear-pinion 69 meshing with a wheel 70 of three times its number of teeth. The wheel 70 is secured to a starwheel 73, the six slots in which, flared outwardly at the ends, are engaged bv two pins 76 on a disc 77 mounted on the main shaft 7. The form of the slots in the star-wheel has the effect of producing an intermittent motion thereof, and in consequence a period of dwell in the movement of the loopers in their intermediate positions. Mounted on a fulcrum supported by posts 80 are loop-detainers 78, 82 co-operating respectively with the threaded and non-threaded loopers 53,. 54. These detainers are moved simultaneously in opposite directions by links 84, 85 connecting their supporting arms on opposite sides of the fulcrum to a cross-head 86 on a vertically reciprocating rod 87. A groove 88 in the rod is engaged by a forked arm 89 projecting from a slide 90 which is reciprocated by the engagement of a roller 92 thereon with a cam groove 93 in the disc 77. The detainer-horns move in a path which passes between the usual throat plate 47a, Fig. 7, and the path of the loopers. The mechanism for rotating the stitch-forming devices is constructed substantially as described in Specification 15049/15. In operation the needle 22 in forming its depth stitch a passes through a loop b of the under-thread held at that moment by the detainer 78 and subsequently drawn up round the loop a by the retraction of the looper 53. The loop a is engaged by the looper 54 and carried to one side, where it is engaged by the detainer 82 and held for engagement by the needle 22 in its next descent for producing the slit stitch, as shown in Fig. 24. As the needle descends, the detainer 82 recedes and the loop a is drawn up bv the thread control. The needle thread on the rise of the needle throws out a second loop a, Fig. 26, which is entered by the threaded looper 53 the thread of which is engaged and held for the subsequent depth stitch descent of the needle by the detainer 78. Governing needle thread.-Mounted on a vertical take-up shaft are spaced take-up cam-plates 107 and a cam 108 actuating the thread-nipper which is engaged by a lever 110 carrying an adjustable push-screw 113 bearing on the spring- pressed nipper-pin 114 to press it against the abutment 115. The cams 108 lie on either side of a slotted plate 121 and between bars 119 all mounted on a normally-movable pivoted bar 118. The thread passes through holes 120 in the bars 119 across the cams 108, through the slot in the plate 121 and through an eve 129 carried by a slack-thread controller or check-spring 128. Needles, vibrating laterally.-The needle jogging mechanism is substantially as described in Specification 15048/15 and comprises a yoke 19 on the needle bar carrying a pin 20 on which is slidably mounted a block 21 carrying the needle 22. An arm 23 depending from a rotary sleeve 18 engages an arm of the yoke and to rotate it and the needle bar. A slotted lever 27 pivoted to the yoke 19 carries an adjustable pin 28 extending into a vertical slot 29 in the needle block 21 to which it communicates lateral movements on the pin 20 when the lever 27 is moved about its pivot. The lever 27 carries a pin 30 engaged by a slotted bell-crank lever 34 and adapted to be diverted thereby so as to slide alternately on the down-stroke of the needle in one of a pair of vertical guide-ways 32. The lever 34 is actuated by the movements of a ring 36 connected to a needle-jogging rod and engaged by a pin on the lever.