Patent GB-651813-A (GB)
Title: Improvements relating to thread rolling dies
Inventor: WHITE FRANK BERNARD
IPC: B21H3/06
Filed: 1948-09-10
Abstract: 651,813. Rolling screw-threads. GUEST, KEEN & NETTLEFOLDS (MIDLANDS), Ltd. Sept. 10, 1948, Nos. 23798/48 and 11851/49. [Class 83 (iv)] In a machine for rolling screw-threads between dies, one of the dies may be rocked so that the working faces are diverged as the blanks are introduced or released from the dies. In one construction a holder 17, Fig. 1, for a fixed platen 23 is mounted at one end on a pivot 21 and at the other end upon an eccentric portion 30 of a pin 25 which passes through a slot 28 in the holder. The pin 25 is normally locked against rotation by a spring plunger 34 which engages a slot 33 in its head. A pin 13 on a plate 12 on the head 11 for the moving platen 10, after disengaging the plunger 34 by pressing against a face 38 towards the end of the working stroke of the platen, engages a face of a sector-shaped slot 32 in the head of the pin 25 and rotates it through approximately 90 degrees to rock the platen for releasing the work and on the return stroke engages the opposite face of the sector-shaped slot 32 to return the platen to its original working position. In a modification a fixed platen 72, Fig. 8, is rocked through a linkage by the motion of an automatic blank feed 77 which is reciprocated by a cam 80 on head 75 carrying the moving platen 73. The linkage comprises an adjustable link 94 and two lost-motion devices, one of which comprises a bell-crank on a pivot 120 which is free to slide in grooves 124 on the machine frame but is limited in its clockwise rotation by a cam face 129 having a projection 131 against which a roller 127 on its arm 122 engages and causes the bell-crank to move bodily to the right as the blank feed 77 descends. The motion is transmitted to a second lost-motion device through a connecting rod 117, Fig. 9, coupled to one end of a lever 108 pivoted at 107 in a sliding block 109 and coupled to a sliding head 102 forming a part of the second loss-motion device and moving in a rectilinear slot 106. The slide 102 has vertical slots 103 engaging pins 98 on a block which slides in slots 101 in a toggle box 97. The slots 101 have arcuate portions 100 wherein the block transmits no motion to the adjustable link 94 and have straight portions 99 wherein the block transmits vertical motion to the link 94 and platen, the movement being limited by the engagements of the ends of a pin 95 against an adjustable stop plate 116. In a further example a moving platen 39, Fig. 6, is rocked in its supporting carrier 42 about links 52, 53 placed transversely to its direction of motion and having cylindrical ends which engage grooves in the carrier and platen. The rocking motion is adjustably limited by camlike abutments 56, 57 which may be rotated and locked in any position. The platen is supported in the carrier by cover-plates (not shown) and the working thrust is transmitted to it through a third link 45 which is free to rock with the platen. As the blank 22 is engaged by the leading ends of the platens 39, 72, the reaction of the blank rocks platen 39 about links 52 in a clockwise direction to facilitate entry of the blank and when the blank is opposite link 52 the platens become parallel and remain so until the blank is opposite link 53, whereupon the platen 39 rocks counter-clockwise to release the blank. Alternatively, if rocking of the platen 39 is required at one end only of its stroke the appropriate abutment 56 or 57 is adjusted to contact the platen holder 40, or the link 52 may be omitted and a fixed abutment placed at 56. In all cases the dies have plain chamfered ends along which the thread forming grooves are not continued.