| 摘要 |
Grooves are produced on the inside of metal tubes by hammering the workpiece in a cold forging machine, such as a rotary die forging machine, over or around a mandrel provided with a screw thread. In the production of internal profiles of great depth, for example in the production of ball bearing nuts made of sintered carbide, grooves and gearwheels with internal toothing, considerable shear stresses occur between the mandrel and the workpiece. The invention provides a method and an apparatus for avoiding unwanted shear stresses on the mandrel and the workpiece by means of a rotatable mounting for the connecting rod, which can in addition be braked, in order in this way to obtain a controllable slip at the friction surface (11) between the workpiece (8) and the connecting rod (10). <IMAGE> |
