Improvements in screw thread cutting tools, such as taps, dies, screw-thread die-plates, screw-thread cutting heads, or the like

摘要

237,776. Wille, E. Sept. 5, 1924, [Convention date]. Screwing-dies ; taps.-A screw-cutting tap or die &c. has two opposing teeth on each convolution of the thread adapted to cut the normal thread profile, while other teeth having their flanks at a more acute angle are provided for acting only on the base of the thread being cut. The teeth f have the normal profile whereas the teeth i have their bases h equidistant from the tool axis b but nearer than the bases d of the teeth f. The outer extremities of the teeth are located in a circle a concentric with the axis and the bases may lie on an ellipse g. The number of acute teeth i may be odd, in which case they are irregularly spaced about a pair of opposite teeth f, and the first cutting teeth of the tool may be tapered off to facilitate entering.