| 摘要 |
PURPOSE:To start a program control with a higher exactitude and to improve the quality of a product by detecting the arrival of a movable platen at a prescribed clamping position from the hydraulic fluid pressure of a cylinder and executing pressing while making program control. CONSTITUTION:A fixed displacement pump in an electromagnetic pressure control valve circuit 60 is drived from the down position of the movable platen 20 to supply a hydraulic fluid at a specified rate to a hydraulic fluid chamber 40 of a clamping cylinder 26. The platen 20 is driven to ascend even after the platen actuates a limit switch 64. The hydraulic fluid pressure in the chamber 40 rises sharply when a work 36 imposed on the uppermost step of a movable hot plate 30 contacts with an upper hot plate 18. As a result, a differetiated hydraulic pressure signal exceeds a reference signal and a clamping signal is supplied via a comparator 48 to an AND circuit 52, by which the circuit 60 and a heating circuit 62 are controlled to the predetermined program. The exact starting of the program control is thus made possible. |
