GB848221A - Improvements in or relating to processes and apparatus for forming external threads on double frusto-conical workpieces - Google Patents

Abstract

848,221. Screw-cutting. SIEMENS-PLANIAWERKE AKTIENGESELLSCHAFT FUR KOHLEFABRIKATE. April 30, 1957 [April 30, 1956], No. 13755/57. Class 83 (3). [Also in Group XXV] Apparatus for forming external screw-threads on a double frusto-conical workpiece I, comprises means for rotating the work about a fixed axis without displacement therealong, means for rotating two thread-forming tools 8, 9, mounted on respectively opposite sides of said axis and each comprising a number of coaxial annular thread-forming members, means for displacing each tool along a line P2 which is parallel to the generatrix of the respective frustum of the - work through a distance equal to the lead of the thread to be formed during a single revolution of the work, and means for adjusting the positions of the tools, to accommodate different work diameters, along paths which are perpendicular to said fixed axis. The tool-slides 6, 7 are adjustable angularly. The thread to be produced is such that a line B perpendicular to the work axis bisects the thread angle α, Fig. 2. The work may be a double-tapered nipple for joining carbon electrodes. As shown in Fig. 3, the cutters may be cylindrical, or have the same taper as the work. A cutter-section 10 on the end of each cutter produces a thread run-out on counter-rotation of the work. The thread is checked by a gauge mounted on the machine, as in Specification 848,222, to determine whether the threads run into each other and are of the correct pitch.