Patent ID: 9156222
Filing Date: 2015-10-13
Classification: B30B,G01B

Abstract:
1. A press machine comprising: a slide; a bolster being located below the slide; an extendable connecting rod with a lower end that is directly connected to the slide or connected to the slide via a plunger; a main shaft comprising an eccentric portion to which an upper end of the connecting rod is connected; a pulse-outputting angle detector being configured to detect a crank angle of the eccentric portion of the main shaft; a servo motor being adapted to drive the main shaft; and a controller being configured to control the servo motor, wherein the controller comprises a top-dead-center detector that is configured to: rotate the main shaft in a predetermined direction selected from a normal rotation direction and a reverse rotation direction to place the slide at a first position displaced relative to a top dead center of the slide by a predetermined height; while outputting and counting pulses from the angle detector, rotate the main shaft in a direction opposite to the predetermined direction to move the slide to a second position located at the same height as the first position beyond the top dead center; and rotate the main shaft from the second position in the predetermined direction by an amount corresponding to a half of the counted pulses to detect the top dead center.