GB496918A - Improvements in thread milling machines - Google Patents

Abstract

496,918. Thread-milling machines. PLOTTNER, W., and HILLE-WERKE AKT.- GES. April 13, 1938, No. 11422. [Class 83 (iii)] A thread-milling machine of the kind in which a cutter with peripheral rings of teeth is given an axial pitch movement relative to the work has the actual movement imparted either to the milling head or to the work by means of a cam acting through adjustable lever mechanism which may be quickly set to cut screws of different pitches. As applied to a planetary type of thread miller, the cutter-spindle 2 driven by a belt pulley 5, is eccentrically mounted in a bush 3 which is itself eccentrically carried in a member 4 which is driven to impart the planetary movement by worm gearing 7. The entire headstock 13 is movable along dovetail guides 8, and a cam 14 mounted in the headstock is driven by gearing 18 so that it rocks a lever 25 pivoted at 26 to the headstock. The back of this lever is maintained by springs 12 in engagement with an abutment 28 mounted in a block 36 secured to the frame and movable transversely of the cutter spindle axis by a screw 32. The lever 25 is graduated so that by adjusting the abutment 28, the same cam 14 may be used to give any required movement of the headstock parallel to the cutter-spindle in accordance with the pitch of the tooth to be cut. A quick return movement is given to the cutter by the cam surface 35. The cam 14 is shaped so that it moves the lever 25 at uniform angular speed. In a modification, the above-described pitch movement may be imparted to the work instead of the cutter. The invention may also be applied to machines wherein the work and cutter both rotate about their respective axes.