Multi-stage tube forging method for dis-proportionally enlarging end section of tube of bicycle frame part, involves dis-proportionally varying cross section of end section of tube by again forging tube in second die using second mandrel

摘要

The method involves radially and proportionally enlarging the cross section of the end section (31) of a tube by forging the tube in a first die (40) using a first mandrel, and dis-proportionally varying the cross section of the end section of the tube by again forging the tube in a second die using a second mandrel. An Independent claim is also included for a bicycle frame part.