GB558580A - Improvements in screw-cutting die heads - Google Patents

Abstract

558,580. Screwing dies and die heads. MOREILLON, A. E. Jan. 13, 1943, No. 630. [Classes 83 (ii) and 83 (iii)] Concentric die heads comprise a ring shaped head 21, that may have handles 30 or may be mounted for use in a machine, in which substantially sector shaped dies 20 are mounted separated by replaceable distance pins 17 that determine the diameter of the thread cut. The dies are grooved on one face at 16 to engage the pins 17 and are circumferentially grooved at 18 to receive a spring retaining ring 19. The dies abut a flange 22 on the head and are closed on the pins 17 by a conical screwed ring 25, that may carry a spaced conically bored boss 31 to receive replaceable guide bushes 33. The dies may be produced from a disc by drilling and tapping a central hole and then turning the periphery into three eccentric segments. The die is divided between the segments and the dies when assembled with the segments forming part of the same circle have the threaded parts 11 eccentrically backed off. In a modification instead of eccentrically turning the periphery the disc is drilled also at 34 and the sections are placed in a jig with pins engaging the holes 34 and are turned so that faces engage abutments bringing the parts into the required eccentric friction. The periphery is then turned or ground concentric with the axes of the disc.