GB356014A - Improvements in collapsing taper-thread taps - Google Patents

Abstract

356,014. Taps. JACKSON, L. MELLERSH-, 28, Southampton Buildings, London.-(Geometric Tool Co. ; Blake Street, New Haven, Connecticut, U.S.A.) Oct. 21, 1930, No. 31598. [Class 83 (iii).] In a collapsing taper-threading screw tap the chasers 20 are adjustable in radial slots 23 in the body 15 by means of a wedge core 17 having interlocking grooved projections 18. A cap 24, secured by screws to the body, confines the chasers. Axial movement is given to the core 17 by means of a parallel-sided inclined slot 32 therein cooperating with a similar projection 35 on an arcuate dog 36, Figs. 3 and 7, transversely slidable in a slot 37 in an axially slidable sleeve 26. Springs 39 normally maintain the dog in its outer position. An outer sleeve 27 slidable on the sleeve 26 has a wedge 42 adjustably secured thereto by a screw 45, the wedge being located in slots 43, 44 in the sleeves and engaging under the dog 36. Springs 47, Fig. 6, located in axial recesses 48 in the sleeve 26 abut against stops 49 in the body 15 to maintain the sleeve normally against an adjustable stopring 29 screwed at 31 on the body. In operation, with the tap in the condition shown in Fig. 3, the tap and work are given relative axial feed, the chasers cutting a parallel thread until an annular disc 51, adjustably attached to the sleeve 27 by axially arranged fingers 53, Fig. 7, meets the work, whereupon the wedge 42 is moved relatively to the body and sleeve 26, causing the dog 36 to be moved radially inwards and thus displacing the core 17 to gradually retract the chasers and cut a tapered thread. When the lower edge 66 of the dog passes the edge 28 of the ring 29 the springs 47 act to draw the sleeve 26, dog 36 and core 17 rapidly rearwards into the interior of the ring, thus collapsing the tap. To re-set the tap, a hand-lever 57, pivoted at 58 in the sleeve 27 and having a ball end 63 located in a recess 69 in the body 15, is rocked forwardly to the position shown in Fig. 3, first causing the front of the sleeve 27 to engage a flange 67 on the sleeve 26 and then drawing forward the sleeve &c. until the dog 36 is withdrawn from the ring 29, whereupon the springs 39 return the dog to the position shown. A spherical portion 59 on the lever rocks in an opening 60 in the sleeve 27 to exclude cuttings. Instead of controlling the tap by means of the disc 51 the handle 57 may be used or a yoke on the machine may engage an annular groove 68 in the sleeve 27.