| 摘要 |
A hydraulic punching machine is disclosed which has a casing having formed therein a piston chamber in which a piston is reciprocably mounted to define a pair of opposed fluid chambers, and a fluid reservoir for containing a hydraulic fluid. The piston has a piston rod carrying a punch for movement into and out of engagement with a die on the casing. Also mounted to the casing is a motor driven pump for pressurizing the fluid. A solenoid actuated spool valve alternately places the fluid chambers in communication with the pump and with a fluid drain. The solenoid is connected to an electric control circuit capable of sensing the extension and contraction of the piston rod. Therefore, upon extension of the piston rod, with the consequent creation of a punch in the work such as sheet steel, the control circuit cases the spool valve to automatically contract the piston rod under fluid pressure.
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