| 摘要 |
PURPOSE:To obtain a titled rack shaft at low cost without lowering the life of a cutting tool by using an electric welded tube as a material, inserting a mandrel having an escape groove into its inner hole, and after forming a flat part or rough tooth form on the outer periphery of the tube by a punch, making finishing work. CONSTITUTION:A material of electric welded tube 1 such as a resistance welded tube etc. on which trace 3 of welding is remaining is placed on the circular arc face 5 of an upper die 4. A mandrel 9 having a back face 7 of circular arcuate form and having an escape groove 8 in longitudinal direction on the back face 7 is inserted to position the trace of welding 3 at the position of the escape groove 8. The tube 1 is thrusted and fixed by the circular arc 11 of the upper die 10, and a flat part or rough tooth form is formed at specified position of the outer peripheral face of the tube 1 by a forming punch 12. Then, finishing work of rack tooth 14 is made by machining or form rolling etc. and a rack shaft of a rack and pinion steering gear is obtained. By this process, products of uniform quality can be obtained at low cost.
|
