| 摘要 |
<p>PROBLEM TO BE SOLVED: To prevent a core from being pushed back by pressurized hydraulic fluid from a high load accompanying casting pressure of molten metal during casting and pressurizing in a core driving cylinder of a die casting machine. SOLUTION: A boosting cylinder 2a communicating to a head side cylinder chamber 22 of an operation cylinder 1 at a boosting chamber 31 side and a control hydraulic circuit are provided. When a load and a rated pressure Pp of a hydraulic pump 25 are balanced during insertion and setting of a core 41, a check valve 21 is closed, then, a sequence valve 34 is opened to make the boosting cylinder 2a depart and to increase pressure of the head side chamber 22. A boost ratio of the boosting cylinder 2a is set to a pressure higher than a pressure in the head side cylinder 22 generated by casting pressure, and a discharge amount of the boosting cylinder 2a is set to a value equivalent to hydraulic fluid compression amount of the head side cylinder chamber 22. The compression amount is automatically corrected by departure of the boosting cylinder 2a.</p> |
