Clamp device

A clamping apparatus configured to align and fix a movable block (2) to a reference block (1), the clamping apparatus comprising:

• a piston (15) which is vertically movably inserted into the reference block (1) in a hermetical manner;
• a lock chamber (16) which is formed above the piston (15) and where pressurized fluid is supplied and discharged;
• a release chamber (17) which is formed below the piston (15) and where pressurized fluid is supplied and discharged;
• an annular plug portion (26) which is projected upward from the reference block (1) so as to be inserted into the movable block (2);
• a diametrically expandable and contractible sleeve (28) which includes a straight inner peripheral surface (29) vertically movably supported by an outer periphery of the plug portion (26) and a tapered outer peripheral surface (30) making an engagement with a tapered hole (11) provided in the movable block (2);
• an output rod (35) which is vertically movably inserted into a cylindrical hole (26a) of the plug portion (26) and is connected to the piston (15) and configured to move the movable block (2) downward when engaged with the movable block (2);
• a plurality of spring-attachment holes (48) which are formed in a recessed manner in an upper wall (16a) of the lock chamber (16), wherein the plurality of spring-attachment holes (48) are provided circumferentially at substantially equal intervals;
• a plurality of lock springs (49), wherein at least one lock spring of the plurality of lock springs is inserted into the spring-attachment hole (48) so as to urge the piston (15) downward;
• a through hole (55) which communicatively connects an outer surface of the reference block (1) to at least one spring-attachment hole (48) below the sleeve (28);
• and
• a pushing member (56) which is hermetically inserted into the through hole (55) so as to face the sleeve (28),
• wherein at least one lock spring (49) of the plurality of lock springs is a compression coil spring that is inserted into the at least one spring-attachment hole (48) communicatively connected by the through hole (55) to serve as an advancing spring (A) so as to urge the sleeve (28) upward through the pushing member (56) with a predetermined force.