Spindle and method for driving the same

摘要

A spindle arrangement is provided for either holding a workpiece or mounting a working tool onto a rotary shaft in a cutting/grinding process. The spindle arrangement includes radial magnetic bearings for rotatably supporting the rotary shaft in a radial direction thereof by using suction forces of electromagnets, displacement sensors provided in the radial direction of the rotary shaft for measuring an amount of positional displacement of the rotary shaft, and a controlling device for comparing the measured amount of the positional displacement and a displacement command and then changing the suction forces of the radial electromagnets based on the compared result so as to cause agreement between the measured amount and the command. Instead of or in addition to those elements, the spindle can include a thrust magnetic bearing for rotatably supporting the rotary shaft in a thrust direction thereof by using suction forces of electromagnets, a displacement sensor provided in the thrust direction of the rotary shaft for measuring an amount of displacement of the rotary shaft, and a controlling device for comparing the measured amount of the displacement and a displacement command and then changing the suction forces of the thrust electromagnets based on the compared result so as to cause agreement between the measured amount and the command. A method for operating the spindle is also provided.