Spindle device for machine tool

摘要

The present invention relates to a machine-tool spindle device compatible both with high-speed cutting and low-speed cutting in spite of a compact size. A machine-tool spindle device (1) includes: a spindle (12); a front housing (11) for rotatably supporting the spindle (12); a first drive motor (13) having a first rotor (13a) installed securely on the spindle (12) and a first stator (13b) installed securely within the front housing (11); a rear housing (14) installed on a rear end side of the spindle (12) in the front housing (11); a second drive motor (15) having an annular second rotor (15a) which is disposed coaxially to the spindle (12) near a rear end of the spindle (12) and which is supported rotatably within the rear housing (14), and a second stator (15b) installed securely within the rear housing (14); a connecting mechanism (30) for connecting the rear end of the spindle (12) and the second rotor (15b) and releasing the connection; and a clamping mechanism (20), disposed within the attaching hole (12a) of the spindle (12) and within the second rotor (15b), for clamping a tool attached to the spindle (12).