GB371160A - An improved method of and mechanism for producing doublelooped knots in thread-knotting machines - Google Patents

Abstract

371,160. Book stitching machines. POLLAK, J. E., 20, Holborn, London.- (Brehmer Geb. ; Plagwitz, Leipsic, Germany.) April 10, 1931, No. 10669. [Class 112.] Knot-tying devices.-Double-looped reef knots are tied in decorative cords such as for greeting cards in a machine in which the free end of the cord or thread, when drawn through the knotting loops to form the primary loop, is gripped by a looping member and formed into a secondary loop, which together with the primary loop, is subsequently held in position by the tightened knotting loops. The machine carries a thread or cord spool 10 feeding a movable guide 12 in known manner. The guide is adjustably arranged to reciprocate on slide bars above a work table 13. An auto. matically adjustable thread or cord tensioning device 10a is also provided. Hooked thread looping needles 14, 15, 16 are reciprocated individually by link mechanism actuated by cam discs 17 on a shaft 17a beneath the table 13. The needle 14 is also given a semi-rotary movement by the inclined slot indicated in Fig. 1. A bifurcated semi-rotary horn 18 forms loops a, b in conjunction with the needle 15. A movable finger 19 on a rocking lever 20 also helps to form the knot. The arm 20 and horn 18 are actuated by mechanism driven by cam slotted discs 22 driven from the shaft 17a by bevel gearing. A thread gripper 21 constructed as described in Specification 360,364 is slidably mounted in a pivoted guide 23 and reciprocates longitudinally of the table 13 to engage the thread-end brought down by the needle 16 and draw it through the loops formed by the needles 14, 15. A secondary thread looping mechanism comprises an arm 24 with a hooked extremity pivoted on the lever 26 and rocked by a lever 31 actuated by cam mechanism 22. In the knotting operation, thread from the spool 10 is placed by the guide 12 on the card in the track of the needles 14, 15, 16 so that these pierce the card and draw the thread down. The loop formed by the needle 14 is opened out by a semi-rotary turn of the needle ready to receive the gripper 21. The loop formed by the needle 15 is engaged by the horn 18 and formed in known manner into knotting loops a, b. The gripper 21 passes through these and through the loop of the needle 14 and seizes the free end of the thread which has been drawn through the card by the needle 16. The gripper draws the thread-end through the loops. Meanwhile the secondary gripper 24 moves forward to catch the rearwardly drawn and trailing thread and is retracted to form the secondary loop. The knot is then drawn taut in the usual way.