GB387417A - Improvements in or relating to screw thread cutting tools - Google Patents

Abstract

387,417. Chasers. MANNESMANNRÍHRENWERKE, 1B, Berger Ufer, Dusseldorf, and SCHWERD, F., 1A, Welfengarten, Hanover, both in Germany. Sept. 14, 1931, No. 25762. [Class 83 (iii).] In a screw-cutting tool wherein only one or other of the sides of the teeth is used for forming the flanks of the thread, each tooth is provided with a cutting surface inclined to the corresponding cutting flank at an acute angle so as to provide top rake for each tooth individually in a plane normal to the thread flank. As applied to a tangential chaser. roughing teeth x are provided which cut on both sides and are given top rake a<2>, normal to the work axis, as shown by the section B-B, (in Fig. 5), whilst the profile teeth y cut on the right hand side only and are given top rake alpha<1> normal to the thread flanks, as shown by the section A-A, (in Fig. 4). A following chaser has teeth which cut on the left side only and are given corresponding top rake. The roughing teeth may be mounted rigidly and the finishing teeth resiliently, e.g. by forming the finishing teeth on a swan-neck portion of the chaser, or alternatively the roughing and finishing teeth may be formed on separate chasers, the former being rigid and the latter resilient.