To provide a spindle unit capable of braking a spindle according to the weights of a mount and a rotary tool.
A spindle unit 26 comprises a rotary tool mounted in a mount, an electric motor 58 driving a spindle 26, and a motor driver. The motor driver 26 includes a plurality of resistors 70 converting the rotary energy of the motor 58 to thermal energy to consume the same and stopping the spindle 26. Force for stopping the spindle 26 is increased by increasing power consumed by the resisters 70 by selectively connecting the resistors 70 to a stator coil 62 when the total weight of the mount and the rotary tool is large, the force for stopping the rotating spindle is decreased by reducing the power consumed by the resistors 70 by selectively connecting the resistors 70 to the stator coil 62 when the total weight is small, thereby the spindle 26 is stopped in a predetermined time by a proper deceleration of rotational speeds.
TAKAHASHI MASAYOSHI
JP2006237332A | 2006-09-07 | |||
JPH10295091A | 1998-11-04 | |||
JP2009164422A | 2009-07-23 | |||
JP2006263894A | 2006-10-05 | |||
JPH0713269A | 1995-01-17 |
US5063319A | 1991-11-05 | |||
US2507918A | 1950-05-16 | |||
US20110097852A1 | 2011-04-28 |
Hiroshi Oue