Rolling die and surface processing method for rolling die

摘要

In a rolling die as a tool for thread-rolling screws, an electrode exhaustion-melted substance or its reactive substance of a discharge electrode (5) generated by discharge energy based on an in-liquid gap discharging is adhered to an deposited onto a rolling cutting-edge surface (100b). Thus, a hard film (110) of the electrode exhaustion-melted substance or its reactive substance is formed on the rolling cutting-edge surface (100b).