Method and apparatus for making metallic, non-rotationally symmetric rings

Abstract

In a method of making a metallic, non-rotationally symmetric ring with substantially constant wall thickness about its circumference, in particular a cam ring, from a circular ring, a circular ring is mechanically machined on both inner and outer sides with an edge-shortening form element and then intermittently fed by a transport belt to an area between two continuously closing and opening die members. The transport belt is hereby positioned with its upper strand below the die members. After closing the die members, the circular ring is shaped through cold forming to a non-rotationally symmetric shape whereby the die members continue to maintain the closed position momentarily before being opened for removal of the non-rotationally symmetric ring from the area between the die members.

1 . A method of making a metallic, non-rotationally symmetric ring with substantially constant wall thickness about its circumference, in particular a cam ring, comprising the steps of: 
 mechanically machining both sides of a circular ring to provide on the inside and outside edge-shortening form elements;    feeding the circular ring incrementally to an area between two continuously closing and opening die members;    closing the die members for cold forming the circular ring into the shape of a non-rotationally symmetric ring;    maintaining the die members in closed position for an additional short time; and    opening the die members for removal of the non-rotationally symmetric ring from the area between the die members.    
   
   
       2 . The method of  claim 1 , wherein the circular ring is cold-formed in horizontal disposition.  
   
   
       3 . The method of  claim 1 , and further comprising the step of continuously lubricating an inner contour surface of each of the die members.  
   
   
       4 . The method of  claim 1 , wherein the edge-shortening form element is a radius.  
   
   
       5 . The method of  claim 1 , wherein the edge-shortening form element is a bevel.  
   
   
       6 . Apparatus for making a metallic, non-rotationally symmetric ring with substantially constant wall thickness about its circumference, in particular a cam ring, from a circular ring, comprising: 
 a frame bed;    a forming tool supported by the frame bed and having an inner contour which approximates a finished contour of a non-rotationally symmetric ring, said forming tool including two die members constructed in the form of two flat disks in opposite disposition and movable back and forth;    an endless transport belt arranged in an area between the die members and so operated as to move in a production clock cycle and to move transversely to the die members, said transport belt having an upper strand extending in immediate proximity underneath the die members.    
   
   
       7 . The apparatus of  claim 6 , wherein the upper strand has a top side spaced from an underside of the die members at a distance which is at least 0.05 mm.  
   
   
       8 . The apparatus of  claim 6 , and further comprising a machining device for shortening an inside edge and an outside edge of a circular blank before the circular ring is placed between the die members for shaping the circular blank into the non-rotationally symmetric ring.  
   
   
       9 . The apparatus of  claim 8 , wherein the machining device is constructed to radius the inside and the outside edges.  
   
   
       10 . The apparatus of  claim 8 , wherein the machining device is constructed to bevel the inside and the outside edges.  
   
   
       11 . The apparatus of  claim 8 , wherein the inside and the outside edges are shortened by up to one millimeter.  
   
   
       12 . The apparatus of  claim 6 , wherein the transport belt is provided in midsection with vertical engagement pins which are spaced apart in length direction of the transport belt.  
   
   
       13 . The apparatus of  claim 6 , wherein the die members have end surfaces in confronting relationship, each said end surface provided with two centering elements.  
   
   
       14 . The apparatus of  claim 13 , wherein the centering elements of one die member are configured with a triangular pointed end, and the centering elements of the other die member are configured with a complementary recess.  
   
   
       15 . The apparatus of  claim 6 , and further comprising a press arranged downstream of the forming tool and having an upper die and a lower die.  
   
   
       16 . The apparatus of  claim 15 , wherein the forming tool and the press are integrated in a common shaping unit.