Threaded neck for bung in thin-walled metal drum is made by stamping and rolling

摘要

The threaded neck is made by stamping the wall (11) of the drum to create a cylindrical neck (14), which then has an internal thread (26) for a bung made by a thread-forming roller (18) while the neck is supported by a rigid ring (20) or similar structure. The rim (16) of the neck is rolled over prior to the thread being made.