Injection molded cold-expansion compression collar

Abstract

A compression collar is manufactured for use in reinforcing an interference fit between an end of a pipe and a fitting. A precursor form is injection molded using a cold-expansion material. The precursor form has a tubular body with an initially closed axial end and a bore that is initially blind formed in the other axial end. Material is removed from the initially closed axial end of the tubular body of the precursor form to form an opening in the initially closed axial end that connects to the bore thereby forming the compression collar. The opening has an inner periphery with a profile in axial cross section that is different than any profile in axial cross section of an inner periphery of the bore. The collar formed may lack knitlines and may include tabs formed during the removal step which help to position the collar on a pipe.

1 . A method for manufacturing a compression collar for reinforcing an interference fit between an end of a pipe and a fitting, the method comprising the steps of:
 a. injection molding a precursor form using a cold-expansion material, wherein the precursor form comprises a tubular body with an initially closed axial end and a bore that is initially blind formed in the other axial end; and   b. removing material from the initially closed axial end of the tubular body of the precursor form to form an opening in the initially closed axial end that connects to the bore thereby forming the compression collar; wherein the opening has an inner periphery with a profile in axial cross section that is different than any profile in axial cross section of an inner periphery of the bore.   
     
     
         2 . The method of  claim 1 , wherein the cold-expansion material is at least one of polyolefin, cross-linked polyolefin, polyethylene, cross-linked polyethylene, PEX, PEX-a, PEX-b, PEX-c, and PERT. 
     
     
         3 . The method of  claim 1 , wherein the compression collar includes no knitlines. 
     
     
         4 . The method of  claim 1 , wherein the step of injection molding involves injecting all cold-expansion material at an injection location positioned on the initially closed axial end, such that the cold-expansion material flows radially outward on the initially closed axial end and then axial downward into generally tubular sidewalls of the tubular body without the material front flow into itself or another material front during the step of injection molding. 
     
     
         5 . The method of  claim 1 , wherein the step of removing material from the initially closed axial end of the tubular body of the precursor form to form an opening involves removing any injection points on the precursor form used in the step of injection molding the precursor form. 
     
     
         6 . The method of  claim 1 , wherein the step of removing material from the initially closed axial end of the tubular body of the precursor form to form an opening in the initially closed axial end involves punching. 
     
     
         7 . The method of  claim 1 , wherein the step of removing material from the initially closed axial end of the tubular body of the precursor form to form an opening in the initially closed axial end forms at least one positioning tab in the inner periphery of the opening. 
     
     
         8 . The method of  claim 7 , wherein the at least one positioning tab includes a plurality of positioning tabs. 
     
     
         9 . The method of  claim 8 , wherein the plurality of positioning tabs are located at even intervals around the inner periphery. 
     
     
         10 . The method of  claim 1 , wherein the compression collar further comprises a supporting extension on the axial end of the compression collar opposite the opening that is removed, the supporting extension being configured to reinforce a thinned section of the pipe past the fitting. 
     
     
         11 . The method of  claim 10 , wherein the supporting extension tapers as it extends away from the opening. 
     
     
         12 . The method of  claim 1 , further comprising, during injection molding, forming flat surfaces on the inner periphery of the bore of the compression collar that are parallel to a central axis of the compression collar such that the flat surfaces are configured to be tangent to a radially-outward facing surface of the pipe around which the compression collar is received. 
     
     
         13 . The method of  claim 1 , further comprising the step of forming a chamfered edge in the bore at the axial end of the bore that is opposite the axial end in which opening is removed. 
     
     
         14 . The method of  claim 1 , further comprising the step of forming a curved corner with a radius of curvature in the bore at the axial end of the bore that is opposite the axial end in which opening is removed. 
     
     
         15 . The method of  claim 1 , wherein the opening has an inner periphery with a profile in axial cross section that matches, in part, an adjacent profile in axial cross section of an inner periphery of the bore with a non-matching part of the profiles providing at least one positioning tab in the inner periphery of the opening. 
     
     
         16 - 27 . (canceled)