Abstract
To prevent galling of billet in forming of hole with high aspect ratio, the forming method with a punch with internal channel for lubricant is proposed using a servo press. In the proposal method, the punch moves in a manner combining pulsed and stepwise modes by controlling the press ram of servo press. Liquid lubricant in the internal channel of the punch is induced to the bottom part of the formed hole during retreating of punch became atmospheric pressure in the hole is reduced. The appropriate forward stroke of the punch for preventing the galling is determined from the amount of the lubricant and the observation of the hole surface.
