A vacuum suction apparatus for a machine tool, the apparatus comprises:
- a suction plate that suctions a workpiece using a vacuum pressure;
- a pneumatic pump that supplies compressed air through a compressed air line;
- a vacuum generator that generates negative pressure by discharging the compressed air to an outside at one end portion of the compressed air line;
- a vacuum solenoid valve that is installed on the compressed air line between the pneumatic pump and the vacuum generator to selectively connect or disconnect a flow path of the compressed air to be supplied to the vacuum generator;
- a vacuum tank having an internal volume and connected to the vacuum generator through a vacuum line;
- a first solenoid valve installed on a suction plate line that connects the vacuum tank and the suction plate, and configured to selectively connect the suction plate line to a high-pressure vacuum or a low-pressure vacuum;
- a drain tank connected to the suction plate through a drain line to collect coolant oil and fine chips from the suction plate using the vacuum pressure;
- a second solenoid valve installed on the suction plate line that connects the first solenoid valve and the suction plate, and configured to selectively connect the suction plate line to the suction plate or the drain tank;
- a third solenoid valve installed on a drain tank vacuum line that connects the second solenoid valve and the drain tank, and configured to connect or disconnect the drain tank vacuum line;
- a fourth solenoid valve installed on a drain line that connects the suction plate and the drain tank, and configured to selectively connect or disconnect the drain line;
- a fifth solenoid valve installed on a discharge line that connects the drain tank to the outside, and configured to selectively connect or disconnect the discharge line;
- a sixth solenoid valve installed on an unclamp line that connects the compressed air line to the suction plate, and configured to selectively connect or disconnect the unclamp line;
- a vacuum release solenoid valve installed between the vacuum line and the compressed air line, and configured to connect the vacuum line with the discharge line through a bypass discharge line and simultaneously with the compressed air line, and selectively connect or disconnect the compressed air line and the vacuum line;
- a control unit electrically connected to the first to sixth solenoid valves and the vacuum release solenoid valve, respectively, and configured to connect or disconnect a flow of the compressed air or the vacuum pressure, or to change a flow direction thereof by switching the said solenoid valves;
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- an operating unit that provides an operating command to the control unit.