Patent ID: 8448543

Claim:
A clamping device ( 2 ) for a rotary index device for a machine tool, the rotary index device ( 1 ) including a rotary shaft ( 5 ), a clamp disc ( 11 ), and clamping means ( 6 ), the rotary shaft ( 5 ) being rotatably provided in a housing ( 3 ) and to whose one end portion a member that is rotationally driven ( 4 ) is mounted, the clamp disc ( 11 ) being mounted to the rotary shaft ( 5 ) so as to be incapable of rotating relative to the rotary shaft ( 5 ), the clamping means ( 6 ) pressing the clamp disc ( 11 ) against a clamp surface ( 12 ), integrated to the housing ( 3 ), and clamping the clamp disc ( 11 ) in cooperation with the clamp surface ( 12 ), in which the clamping means ( 6 ) is normally urged towards the clamp disc ( 11 ) by urging means ( 10 ) to maintain an index position of the member that is rotationally driven ( 4 ), and in which, when an indexing operation is performed, unclamping means ( 13 ) stops the urging means ( 10 ) from urging the clamping means ( 6 ) to cause the member that is rotationally driven ( 4 ) to be capable of rotating, wherein the clamping means ( 6 ) includes: a fixing portion ( 7 ) fixed to the housing ( 3 ); a resiliently deformable supporting portion ( 8 ) joined to the fixing portion ( 7 ) at one end thereof, a pressing portion ( 9 ) having a face that opposes the clamp disc ( 11 ) being provided at the other end thereof; and the urging means ( 10 ) that normally urges the supporting portion ( 8 ) towards the clamp disc ( 11 ) to realize a state in which the clamp disc ( 11 ) is pressed by the pressing portion ( 9 ), the urging means ( 10 ) extending in a circumferential direction along a circumference having an axial line of the rotary shaft ( 5 ) as center, and wherein the clamping means ( 6 ) is a spring member ( 14 ) in which the fixing portion ( 7 ) and the supporting portion ( 8 ) are integrally formed with each other, and in which the supporting portion ( 8 ) functions as the urging means ( 10 ).