GB253102A - Improvements in thread cutting devices - Google Patents

Abstract

253,102. Bruno, R. June 4, 1925, [Convention date]. Void [Published under Sect. 91 of the Acts]. Dies; chasers; taps. -Screw-cutting dies, taps, chasers &c. have teeth whose operative sections increase progressively to the full cross section of the thread, commencing from a corner of the full cross section. The preliminary teeth have the sections 47, 53, 52; 47, 51, 50; 47, 49, 48; and 47, 46, 45, Fig. 1, respectively, or the amount of material removed by each tooth may be halved as shown by the dotted lines and double the number of teeth provided on the tap &c. The point 47 from which the tooth-section commences may be either at the front or rear end of the thread and the lines 53, 52 &.c. which bound the advancing side of the section may be parallel to a face of the thread as shown or inclined thereto. The section of the thread may be divided into equal areas to be removed by each tooth, or the areas may decrease successively. The first teeth a, b, c, Fig. 7, may have the triangular shape as described above and the next succeeding teeth d-g may be of the same height as the tooth c but of increasing width, the last teeth h, i, j increasing in height and width similar to the teeth a, b, c. Fig. 11 shows a tap having complete teeth on a tapered core. The plates of taps and dies may be straight, helical or combined straight and helical, the direction of the helix being opposite to that of the threads, and the section of the plates may have two or more centres. The teeth may be smoothed on their edges or on one or both sides.