Clamping device

A clamping device for releasably holding a tool holder shank formed with an engagement bore in a rear end, comprising:

• a housing having a forwardly facing surface and a mounting bore intersecting the forwardly facing surface and extending rearward therefrom for receiving the tool holder shank;
• a drawbar mounted reciprocally movable inside the housing and which in a forward end is provided with an engagement segment arranged to engage with an engagement formation inside the engagement bore of the tool holder shank, the drawbar being in a rear portion formed with a drawbar aperture extending through the drawbar in a transverse direction in relation to a longitudinal axis of the same, an inside surface of the drawbar including a pair of leg portions, each leg portion having a reinforcing ridge extending parallel to the longitudinal axis;
• and
• a cam shaft extending through the drawbar aperture and including a cam formation, wherein the cam shaft is rotatably journalled in the housing and arranged to impart an axial displacement to the drawbar in relation to the housing by the cam formation when rotating the cam shaft, wherein the cam shaft includes two identical cam formations, which are spaced apart by a recess, and which each cam formation comprises a first cam surface operable to urge the drawbar rearward to a locked position, in which it firmly locks the tool holder shank to the clamping device, and a second cam surface operable to positively displace the drawbar forward to an unlocked position in which the tool holder shank is releasable from the clamping device, wherein the reinforcing ridges are located on each side of the aperture in a direction in parallel to a longitudinal axis of the drawbar, each ridge fitting in the recess of the cam shaft which divides the cam formation into the separate first and second cam formations when rotating the same.