High speed spindle unit and driver.

摘要

High speed cutting with machine tools is achieved with readily available bearings (33,35,37) of a small diameter by mounting and presetting the cutting tool (27) directly in a spindle (31) of a spindle unit (23) without employing a tool holder. Preferably, the spindle unit (23) is small like a tool holder and can be easily changed with conventional kinds of tool changing apparatus. The elimination of the tool holder allows the conventional bearings to be kept small so that they may be operated at high speeds, e.g., 20,000 to 40,000 rpm, without excessive heat that would damage the bearings.