Modification of lathe or milling machine to cut variable pitch screw - uses cam or jack to vary speed of slide upon which work or tool is mounted

摘要

The attachment modifies a milling machine or a lathe to cut a screw thread of variable pitch, using either a cam or a jack to control the movement of the slide upon which either the work or the tool is mounted. In the case of the milling machine the work i.e. a blank screw (1) may be rotated by an axle (2) connected to a divider (5) by a sliding keyed sleeve (3). A slide (4) moves the blank relative to the table (9) and at a varying speed determined by the progress of an axle end roller (6) following the perimeter of a rotating cam (7).