Cold-forming plugs and connecting pieces

摘要

The blank consists of a plate of suitable thickness which is pre-formed into the shape of a cup, and the section which is to have a helical thread is staved up. The pre-forming operation includes the formation of devices which allow the object to be subsequently rotated. The workpiece is further compressed to form a collar between the section to e threaded and the devices permitting rotation, after which the helical thread is cut. Used for central heating and piping systems.