Patent ID: 6979156

Claim:
A machine spindle comprising: a casing defining a center axis; and a clamping device disposed in the casing for clamping a tool, the clamping device comprising: front and rear drawbars arranged substantially coaxially in the casing, the front drawbar having a clamp at its front end for gripping a tool in response to rear movement of the front drawbar, the clamp disposed within the casing, the rear drawbar being axially movable relative to the front drawbar; a spring for biasing the rear drawbar rearwardly; and a wedge assembly for transmitting rearward movement of the rear drawbar to the front drawbar for rearwardly moving the front drawbar, the wedge assembly comprising a plurality of sets of wedges spaced circumferentially apart, each set including a radially inner wedge and a radially outer wedge arranged in sliding contact with one another, the inner wedge arranged to be displaced rearwardly by the rear drawbar for displacing the outer wedge generally radially outwardly, wherein the inner and outer wedges include respective parallel planar surfaces arranged in surface contact for cooperative sliding engagement with one another and oriented at an oblique angle with respect to the axis.