Expansion device for hollow bodies

Abstract

An expansion device for hollow bodies, such as pipe ends having a base body ( 1 ) in which a bore ( 11 ) for the axial guidance of a displaceable, a tapering spreading member ( 10 ) is disposed, and having an expansion head ( 13 ) which contains a thimble ring ( 14 ), and sector-shaped spreader jaws ( 15 ) and is releasably joined to the base body ( 1 ). The spreader jaws ( 15 ) are guided for radial displacement in the thimble ring ( 14 ) by the axial movement of the spreading member, and friction surfaces are provided with a coating of a hard material to reduce attrition. In one embodiment at least the portion of the spreading member ( 10 ) that acts upon the spreader jaws ( 15 ) is provided with a coating ( 18 ) made of the hard material, e.g., titanium nitride (TiN).

1 - 9 . (canceled)  
   
   
       10 . An expansion device for hollow bodies 
 comprising a basic body in which a bore is disposed for the axial guidance of a displaceable, tapering spreading member;    an expansion head which contains a thimble ring with sector-shaped spreading jaws and is releasably fastened to the basic body;    wherein the spreading jaws are guided for radial displacement in the thimble ring by the axial movement of the spreading member, and wherein slide surfaces are provided with an attrition reducing coating of a hard material, wherein at least the portion of the spreading member acting on the spreading jaws is provided with the coating of the hard material.    
   
   
       11 . The expansion device according to  claim 10 , wherein the hard material comprises titanium nitride (TiN).  
   
   
       12 . The expansion device according to  claim 10 , wherein the coated surface of the spreading member has a conical surface.  
   
   
       13 . The expansion device according to  claim 10 , wherein the spreading member is fastened replaceably to a driving rod which is positioned in the bore of the basic body.  
   
   
       14 . The expansion device according to  claim 10 , wherein interior surfaces of the spreading jaws are made as sectors of a conical surface and are coated with the hard material.  
   
   
       15 . The expansion device according to  claim 14 , wherein the hard material comprises titanium nitride (TiN).  
   
   
       16 . The expansion device according to  claim 10 , wherein the exterior surfaces of the spreading jaws are configured as sectors of a cylinder surface and are coated with the hard material.  
   
   
       17 . The expansion device according to  claim 16 , wherein the hard material consists of titanium nitride (TiN).  
   
   
       18 . The expansion device according to  claim 10 , wherein the coating is applied by a process selected from the group consisting of physical vapor depositions (PVD), chemical vapor deposition (CVD) and physico-chemical vapor deposition (PCVD).