Guidage barrel for screw cutting lathe - is internally reamed and tapered sleeve containing inner radially mobile tapered cylinder segments

摘要

The guidage barrel or chuck for locating and securing a workpiece bar in the head of a screw cutting lathe, effects great precision. It constitutes externally tapered cylindrical segments (2) contained in an internally tapered sleeve (1) and motivated by rotation of a threaded sleeve (3) to displace longitudinally and, thus displace radially and grip and centre the workpiece bar. The outer sleeve (1) and inner cylinder segments (2) are both reamed (4, 5) and a reamed face (4) is brought to bear on the workpiece. Cylinder segments (2) are of hard metal, ceramics, or steel of which the reamed face is lined with hard metal or ceramics. They can have wholly conical external faces (5), or simply have reversely conical lengths at each end.