Millen, White, Zelano & Branigan, P.C. `Nixon William
摘要：
A forging method is set in a shaping hole of a die body, and the forging material is pressed with a punch to perform plastic shaping of the forging material. Ultrasonic vibration having a vibration frequency is applied to the die body with a vibration applying apparatus during the plastic shaping of the forging material. The vibration frequency is converged to a resonance frequency of the die body when the vibration frequency is within a tracking range of the vibration applying apparatus during the plastic shaping of the forging material. When the tracking range is shifted in accordance with a discontinuous change of the resonance frequency during the plastic shaping of the forging material to deviate from the vibration frequency, the reference frequency is changed so as to fall within a shifted tracking range.
