| 摘要 |
PURPOSE:To aim at the manufacturing of a highly accurate rack forging die at one process for both warm and hot forging stage, by setting a pinion, which regularly engages such one as being expanded in time of warm forging of a rack for a steering gear down to a tool, and thereby forming the same tooth profile in a blank in time of its expansion. CONSTITUTION:With the value multiplying dimensions in the normal temperature by a coefficient of thermal expansion, hobbing and grinding take place, through which a pinion 1' in the same form as such one as making a pinion 1 for a rack-and-pinion type steering gear into thermal expansion is secured. Next, with the tool 1', after a tooth profile of an electrode rack is formed under conditons for forming a rack tooth profile having a form in a state of being thermal- expanded, namely, the value multiplying the amount of travel in a rack-an-pinion in time of the normal temperature by a coefficient of thermal expansion, it is shaped up as the electrode rack. And, using this electrode rack, a forging die is manufactured by means of an electro-discahrge maching process. Therefore, when the rack is formed by warm or hot forging with this forging die, in the case where the rack is cooled and contracted in size, the desired rack form for a steering gear can be produced. |
