Roller Set Having a Burnishing Roller

Abstract

A roller set for roll forming pipe elements has an outer roller that engages the pipe element at three points to prevent teetering of the pipe element. The outer roller has a summit positioned on a raised feature, the summit comprising a curved surface adapted to burnish the pipe elements.

What is claimed is: 
     
         1 . A roller set for forming regions of a pipe element having an inner and an outer surface, said roller set comprising:
 an inner roller engageable with said inner surface, said inner roller comprising an inner roller body, a flange extending circumferentially around said inner roller body;   an outer roller engageable with said outer surface, said outer roller comprising:   an outer roller body rotatable about a first axis, said inner roller body being rotatable about a second axis, said flange projecting transversely to said second axis and being engageable with an end of said pipe element;   a first raised feature comprising a first summit engageable with said pipe element and extending circumferentially about said outer roller body, said first raised feature projecting radially from said first axis, said first summit comprising a curved surface adapted to burnish a portion of said pipe element;   a second raised feature comprising a second summit, engageable with said pipe element and extending circumferentially about said outer roller body and projecting radially from said first axis, said second raised feature being positioned adjacent to said first raised feature;   a third raised feature comprising a third summit, engageable with said pipe element and extending circumferentially about said outer roller body and projecting radially from said first axis, said second raised feature being positioned between said first and third raised features; wherein   said first and third summits are arranged in spaced relation away from said second summit.   
     
     
         2 . The roller set according to  claim 1 , wherein said curved surface is positioned in spaced relation away from an end of said first raised feature. 
     
     
         3 . The roller set according to  claim 2 , wherein said first summit comprises a flat surface positioned between said curved surface and said end of said first raised feature. 
     
     
         4 . The roller set according to  claim 3 , wherein said flat surface is oriented parallel to said first axis. 
     
     
         5 . The roller set according to  claim 1 , wherein said second raised feature comprises a ring surrounding said outer roller body, said ring being rotatable about said first axis relatively to said outer roller body. 
     
     
         6 . The roller set according to  claim 5 , further comprising a plurality of bearings positioned between said ring and said outer roller body. 
     
     
         7 . The roller set according to  claim 1 , wherein said inner roller comprises:
 a first depression extending circumferentially around said inner roller body and positioned adjacent to said flange;   a second depression extending circumferentially around said inner roller body and positioned adjacent to said first depression; wherein   when said inner and outer rollers cooperate to form said region of said pipe element said first and second raised features align respectively with said first and second depressions.   
     
     
         8 . The roller set according to  claim 7 , further comprising a third depression extending circumferentially around said inner roller body and positioned adjacent to said second depression, and wherein when said inner and outer rollers cooperate to form said region of said pipe element said first, second and third raised features align respectively with said first, second and third depressions. 
     
     
         9 . The roller set according to  claim 1 , wherein said second raised feature of said outer roller comprises a first projection extending circumferentially around said outer roller body and projecting radially from said first axis, said first projection having a first contact width over which it contacts said outer surface of said pipe element during roll forming, said roller set further comprising a second projection extending circumferentially around said inner roller and projecting radially from a second axis arranged coaxially with said inner roller, said second projection having a second contact width over which it contacts said inner surface of said pipe element during roll forming.