| 摘要 |
A rotary tool holder assembly comprising a collet ( 2 ) carried by a shaft ( 1 ). The collet ( 2 ) is moveable relative to the shaft ( 1 ) between a tool gripping position, in which an inserted tool can be gripped for rotation, and a tool release position. In some cases, the shaft ( 1 ) comprises a bore, an inner surface of which is shaped for contact with an outer surface of the collet ( 2 ). The shaft ( 1 ) and collet ( 2 ) are shaped such that when the rotary tool holder assembly is rotated at a predetermined high speed the shape of the inner surface of the shaft ( 1 ) substantially matches the shape of the outer surface of the collet ( 2 ). A friction reducing coating is provided between at least a portion of the inner surface of the shaft ( 1 ) and the outer surface of the collet ( 2 ). In alternatives, particular parts of the rotary tool holder may have a friction reducing coating. |
