Cold pilger rolling of tubes, esp. steel tubes - to achieve max. output of tube with accurate dimensions for mfg. ball bearing races

摘要

Cold pilger rolling of tubes, esp. to mfr. races for ball bearings. The tube is rolled onto a stationary mandrel via a pair of grooved rolls rotating in a reciprocating roll stand. During the forward stroke (I) of the stand, the tube is released before the end of stroke (I); and during the reverse stroke (II) of the stand the tube is also released before the end of the stroke (II). The rolls travel through more than 330 deg. during both strokes (I), (II); and the tube is rotated and driven forward while it is free at the end of both strokes. The forward feed rate (IIa) at the end of stroke (II) is different from the forward feed rate (Ia) of the tube at the end of stroke (I); and rate (IIa) may be faster or slower than rate (Ia). The output of the rolling mill can be increased.