| 摘要 |
<p>A method for producing a rack bar for a steering mechanism in an automobile. A blank pipe (18) is held in a die (12,14), which has, at its inner surface, linear toothed portions (12-1). Mandrels (20A,20B) are inserted repeatedly to the blank pipe (18) while the direction of the insertion is alternately changed, while the insertion of the mandrel (20A,20B) on one side of the blank pipe (18) and the withdrawal of the mandrel (20A,20B) on the other side are overlapped. Furthermore, a positive cooling of the die is prevented in such a manner that an increased temperature of the work around 200 DEG C in a range providing a work softening phenomenon is kept. An increased precision as well as reduced cost are obtained irrespective of a fact that the rack bar is produced under metal forming principle. <IMAGE></p> |
