Patent ID: 8590878

Claim:
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 ( 26 a ) of the plug portion ( 26 ) and is connected to the piston ( 15 ) to move the movable block ( 2 ) downward; a spring-attachment hole ( 48 ) which is formed in a recessed manner in an upper wall ( 16 a ) of the lock chamber ( 16 ); a lock spring ( 49 ) which 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 the spring-attachment hole ( 48 ) below the sleeve ( 28 ); a pushing member ( 56 ) which is hermetically inserted into the through hole ( 55 ) so as to face the sleeve ( 28 ); and an advancing spring (A) which is constituted by a compression coil spring and is arranged below the pushing member ( 56 ) so as to urge the sleeve ( 28 ) upward through the pushing member ( 56 ) with a predetermined force.