Reciprocating mandrel for forming sockets on plastic pipe - by deflecting hard elastic collar to create an undercut socket profile

摘要

Mandrel is used for producing a tulip or undercut socket on the end of a thermoplastic pipe by aligning the pipe end with one end of a hydraulic chamber enclosing two coaxial pistons. The larger piston has a conical nose which produces a tubular dilation of the pipe end. Once the full depth of the basic socket has been formed, the inner piston advances through the outer mandrel so that radially projecting shoes on the inner piston deflect a hard but elastic collar mounted behind the nose of the larger piston to produce further local radial dilation of the pipe socket profile. Reversing the sequence of the piston motions allows the flexible collar to retract within the socket and retire through the relatively small socket mouth as shown.