Hydro chuck

A hydro chuck comprising:

• a shank portion provided on one end side in a longitudinal direction and having, on a leading end side thereof, a cylindrical chuck portion for gripping a gripped object;
• an operational portion provided on the other end side in the longitudinal direction and disposed in continuation from the shank portion;
• the shank portion being non-rotatably fixable by being inserted to a tool mount included in a machine tool;
• the operational portion being provided at a position on a side opposite to the chuck portion across the tool mount and not opposed to a workpiece to be worked, with the shank portion being inserted to the tool mount;
• the gripped object being insertable from the side of the chuck portion toward the side of the operational portion;
• the chuck portion including a sleeve gripping the gripped object and a fluid pressure chamber formed on an outer circumference side of the sleeve and filled with fluid, the chuck portion being configured such that in association with a rise of a pressure of the fluid inside the fluid pressure chamber, the sleeve is reduced in its diameter to grip the gripped object;
• the operational portion including a communication passage communicated to the fluid pressure chamber, a pressurizing piston disposed in the communication passage and adjusting the pressure of the fluid inside the fluid pressure chamber, a coolant hole connectable to a supply source of coolant and a coolant passage communicated to the coolant hole and supplying the coolant to the inner circumference side of the sleeve,
• wherein, of the communication passage, a first communication passage accommodating the pressurizing piston and extending along an operational direction of the pressurizing piston is provided with an inclination toward a side opposite to the shank portion, relative to a direction perpendicular to a longitudinal axis of the chuck portion and traverses the axis of the chuck portion, such that if a plurality of hydro chucks is mounted to the tool mount and with the hydro chucks adjacent to each other, a tool for operating the pressurizing piston of a first hydro chuck does not come into contact with the operational portion of a second hydro chuck adjacent the first hydro chuck, and
• an opening of the coolant hole and an opening of a screw hole in which the pressurizing piston is attached are adjacent each other and on a same side in the operational portion as seen in a direction of the axis of the chuck portion and are operable from a same direction, with the shank portion being inserted into the tool mount.