Mechanical pipe expander

Abstract

A mechanical pipe expander with a pyramidal polyhedron and with segments which are arranged on the circumferential surfaces of the polyhedron and can be moved radially by axially displacing the polyhedron relative to the segments. A wear lining is arranged between each of the surfaces of the polyhedron and each respective segment.

We claim:  
     
         1 . A mechanical pipe expander comprising 
 a pyramid polyhedron having a central axis and circumferential surfaces;    segments arranged on the circumferential surfaces of the polyhedron, which segments are moved radially by relative axial movement of the polyhedron; and    a wear-resistant lining between each of the circumferential surfaces and each respective segment.    
     
     
         2 . The mechanical pipe expander as claimed in    claim 1   , wherein the wear-resistant lining is made of a carbon fiber composite, with a polymer matrix.  
     
     
         3 . The mechanical pipe expander as claimed in    claim 2   , wherein graphite powder is added to the matrix, in such an amount as to give a coefficient of friction between 0.10 and 0.15 for the wear lining.  
     
     
         4 . The mechanical pipe expander as claimed in    claim 1   , wherein the segments have axial end faces which are provided with the wear-resistant linings.  
     
     
         5 . The mechanical pipe expander as claimed in    claim 1   , wherein the pyramidal polyhedron is a truncated pyramid.  
     
     
         6 . The mechanical pipe expander as claimed in    claim 1   , wherein the polyhedron has an octogonal cross-section.