PURPOSE: To temporarily retain the position of a main roll and to surely reduce the thickness deviation of a work by advancing the main roll from a waiting position at a fast feed speed, reducing a feed speed in sequence as far as the sizing position of the work and stopping the work from being advanced and retreating it at a fast speed to the waiting position after the work arrives at the sizing position.
CONSTITUTION: The main roll 1 of a ring rolling machine to press and form the work 3 to a prescribed shape and size as it is rotated between the main roll 1 and a mandrel 2 is advanced from the waiting position as far as the position abutted on the work at a fast feed speed. Then, after it is abutted on the work 3, the work 3 is pressed and advanced at a low feed speed moderater than the quick feed speed as far as a starting position of sizing feed. Then, after it arrives at the starting position of sizing feed, the work 3 is pressed and advanced as far as the sizing position of the work at a sizing feed speed further moderater than the low feed speed. When the work arrives at the sizing position of the work, it stops its advance and retreats as far as the waiting position at the quick feed speed.
YAMAGUCHI MASAKI