GB414579A - Dies for cutting external screw threads - Google Patents

Abstract

414,579. Screwing dies and dieheads. CROSS, E. J., 10, New Court, Lincoln's Inn Fields, London.-(Dardelet Threadlock Corporation ; 120, Broadway, Manhattan, New York, U.S.A.) Jan. 10, 1934, No. 964. [Class 83 (iii).] In a die-head for cutting external self-locking screwthreads of the " Dardelet " type, the cutting edges of the chasers are arranged as shown in Fig. 4. Each chaser has inclined and axial trueing surfaces T, F, and a preliminary cutting tooth R<1>-R<4>. The tooth R<1> is reduced at the sides and also in height, the tooth R<2> has the full width of the final thread groove but a height less than the tooth R', the tooth R<3> has a base width equal to that of the thread groove but is reduced at the sides, and the tooth R<4> has the full width of the thread groove but a height slightly less than the tooth R<3> and has a crest inclined to the thread axis at the same angle as the self-locking base of the final thread. Each chaser also has a number of following teeth R of the full thread contour, the crests having the same axial inclination as the tooth R<4>, and the root diameter B, B of all the teeth being constant. The first two teeth of each chaser are given the correct cutting angle by means of an inclined face C, Fig. 5, on the inner end thereof, the plane of the face C being parallel to the die-head axis. The non-cutting end face L of the remaining teeth R is inclined to the head axis so that the following teeth overlap the work more than the first ones, to assist the guiding action of these teeth. The cutting edges described may be applied to the tangential chasers of a pivoted-carrier diehead, as shown in Fig. 5, or to the radial chasers of the die-head shown in Fig. 9, wherein the radial chasers 25<a> are secured in a body 27, slotted at 27b, and adjusted by a split clamping ring 26. Specifications 242,299, [Class 89 (i)], and 342,080 are referred to.