Cold forming process for manufacturing ball pivots

Abstract

A cold forming process for manufacturing ball pivots with a ball area, a cone area and a thread area for installation in ball and socket joints by cold forming is presented, in which a ball pivot blank ( 1 ) with a shaped cone area ( 3 ) and cylindrical areas for the thread ( 2 ) and the ball ( 5 ) is manufactured at first from a bar-shaped semifinished bar stock by extrusion. The extrusion operation is followed by the forming of the ball area as another manufacturing step by means of a rolling processes. At the same time, the thread area can be formed in its final shape. Thus, the ball pivot is manufactured as a whole by cold forming only and it makes it possible to significantly increase the production output per unit of time compared to the processes known from the state of the art. At the same time, it is possible to use less expensive grades of steel, because sufficient fatigue strength of the ball pivot can be guaranteed by the cold forming.

1 . A cold forming process for manufacturing ball pivots with a ball area, the process comprising:
 manufacturing a ball pivot blank with a shaped cone area and cylindrical thread area and cylindrical ball area from a bar-shaped semifinished bar stock by extrusion, wherein an extrusion flash is arranged at the free end of the ball area;   subsequently, in at least one other operation, forming a ball by means of a rolling process by rolling forming bodies.   
   
   
       2 . A process in accordance with  claim 1 , wherein the rolling process is a triggered synchronized rolling process. 
   
   
       3 . A process in accordance with  claim 1 , wherein the thread area is formed simultaneously with the forming of the ball area into its final shape. 
   
   
       4 . A process in accordance with  claim 1 , wherein the cone area is smoothed simultaneously with the forming of the ball area into a ball final shape. 
   
   
       5 . A process in accordance with  claim 1 , wherein a blind hole-like recess is opened on a front side and is pressed into the free end of the ball pivot blank intended for forming the ball area before the rolling operation. 
   
   
       6 . A process in accordance with  claim 5 , wherein the recess is formed by the upper die used during pressing. 
   
   
       7 . A process in accordance with  claim 1 , wherein a cylindrical neck area is formed at first during rolling between the cone area and the cylindrical ball area. 
   
   
       8 . A process in accordance with  claim 1 , wherein a flat-jaw rolling process is used as the rolling process. 
   
   
       9 . A process in accordance with  claim 1 , wherein a round-jaw rolling process is used as the rolling process. 
   
   
       10 . A process in accordance with  claim 9 , wherein round-jaw rollers used in the round-jaw rolling process are designed as rolling cylinders, which are located next to one another on parallel axes of rotation, and whose outer contour has half of the negative form of the contour of the ball pivot to be rolled, wherein the ball pivot is arranged in a roll gap between the rolling cylinders during the rolling process. 
   
   
       11 . A process in accordance with  claim 9 , wherein the round-jaw rollers are formed by a rolling cylinder, on the one hand, and by a hollow cylinder concentrically surrounding the rolling cylinder, on the other hand, wherein the outer contour of the rolling cylinder and the inner contour of the hollow cylinder form half of a negative form of the contour form of the ball pivot to be rolled, which said negative form is variable over the outer circumference and the inner circumference, and wherein the ball pivot is arranged in the roll gap between the outer contour and the inner contour of the rolling cylinder and the hollow rolling cylinder during the rolling process. 
   
   
       12 . A cold forming process for manufacturing ball pivots, the process comprising the steps of:
 manufacturing a ball pivot blank with a shaped cone area a cylindrical thread area and a cylindrical ball area from a bar-shaped semifinished bar stock by extrusion, wherein an extrusion flash is arranged at the free end of the ball area;   subsequently, in at least one other operation, forming a ball by means of a rolling process by rolling forming bodies.   
   
   
       13 . A process in accordance with  claim 12 , wherein the rolling process is a triggered synchronized rolling process. 
   
   
       14 . A process in accordance with  claim 12 , wherein the thread area is formed simultaneously with the forming of the ball area into its final shape. 
   
   
       15 . A process in accordance with  claim 12 , wherein the cone area is smoothed simultaneously with the forming of the ball area into a ball final shape. 
   
   
       16 . A process in accordance with  claim 12 , wherein a blind hole-like recess is opened on a front side and is pressed into the free end of the ball pivot blank intended for forming the ball area before the rolling operation. 
   
   
       17 . A process in accordance with  claim 16 , wherein the recess is formed by the upper die used during pressing. 
   
   
       18 . A process in accordance with  claim 12 , wherein a cylindrical neck area is formed at first during rolling between the cone area and the cylindrical ball areal. 
   
   
       19 . A process in accordance with  claim 12 , wherein the rolling process is a round-jaw rolling process using round-jaw rollers designed as rolling cylinders, which are located next to one another on parallel axes of rotation, and whose outer contour has half of the negative form of the contour of the ball pivot to be rolled, wherein the ball pivot is arranged in a roll gap between the rolling cylinders during the rolling process. 
   
   
       20 . A process in accordance with  claim 12 , wherein the rolling process is a round-jaw rolling process using the round-jaw rollers formed by a rolling cylinder, on the one hand, and by a hollow cylinder concentrically surrounding the rolling cylinder, on the other hand, wherein the outer contour of the rolling cylinder and the inner contour of the hollow cylinder form half of a negative form of the contour form of the ball pivot to be rolled, which said negative form is variable over the outer circumference and the inner circumference, and wherein the ball pivot is arranged in the roll gap between the outer contour and the inner contour of the rolling cylinder and the hollow rolling cylinder during the rolling process.