| 摘要 |
PURPOSE:To obtain a die bush possessed of a long durable life with low working cost, as to the die bush for upsetting by an electric upsetting type forming, by cladding on the die bush main body made of copper alloy with a metal coating layer having a lower electric conductivity than said bush. CONSTITUTION:The die bush 20 is possessed of the cylindrical die bush main body 20a and said main body 20a is formed of a copper alloy such as beryllium copper, etc. Then, hard Cr plating layer 22 are formed on the internal surface which is brought into contact with a work 2 of the body 20 (10 in a figure), an outer peripheral surface and an end surface which are brought into contact with a contact spacer bush 8 supporting the body 20a. As the die bush 20 possesses the layer 22, so an abrasion of the inner surface by repeated workings is reduced, or even when worn, a change of cooling speed is suppressed by the portion of the layer 22 on the outer peripheral surface. Furthermore, as the electric conductivity of the layer 22 is lower than that of the body 20a, so even if the ratio of the outer diameter to the inner diameter becomes below the critical value, controlling the electric current by the deference of the conductivity, any faulty in forming is prevented and the upset forming to form the work 2 into the set shape is performed.
|
