| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a hydraulic drive unit capable of dispensing with a pressure sensor for changeably controlling drive speed of a hydraulic actuator between low speed and high speed at set drive speed by set values. <P>SOLUTION: Both ports 11 and 12 of a hydraulic pump 10 capable of rotation in both directions are connected to both chambers 4 and 5 of a pressure pin cylinder 1. A control part 24 is provided to control the rotation frequency of a servo motor 15 to drive rotation of the hydraulic pump 10. The control part 24 controls the rotation frequency of the servo motor 15 to control the drive speed of a pressure pin 3 to be changed from low speed to high speed when rotation torque of the servo motor 15 reaches a set value as a value indicating a solidified state of molten metal 9 in which the rotation torque of the servo motor 15 has squeezing effect. The pressure sensor to detect pressure of hydraulic fluid to be supplied to a cap side chamber 4 of the pressure pin cylinder 1 can be dispensed with, and wiring can be reduced. <P>COPYRIGHT: (C)2004,JPO</p> |
