US 5,573,443 AGranted

Spindle and method for driving the same

AssigneeMatsushita Electric Industrial Co., Ltd.

InventorsIssei Yasuda, Masayuki Takahashi, Toru Nakagawa

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Abstract

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.

Claims8

Dependent claims

A spindle arrangement for use in holding a workpiece or mounting a work tool on a rotary shaft in a cutting or grinding process, said spindle arrangement comprising:

a plurality of electromagnetic bearings for rotatably supporting the rotary shaft with radially directed electromagnetic forces;
first, second, third and fourth pairs of displacement sensors provided radially about a rotational axis;
wherein said first and second pairs of said displacement sensors are provided at a first axial location, and said third and fourth pairs of said displacement sensors are provided at a second axial location spaced axially away from said first axial location;
wherein said first pair of said displacement sensors are located in diametrically opposite positions with respect to said rotation axis;
wherein said second pair of said displacement sensors are located in diametrically opposite positions with respect to said rotation axis, and said diametrically opposite positions of said second pair of said displacement sensors are angularly displaced by 90 degrees relative to said diametrically opposite positions of said first pair of said displacement sensors;
wherein said third pair of said displacement sensors are located in diametrically opposite positions with respect to said rotation axis;
wherein said fourth pair of said displacement sensors are located in diametrically opposite positions with respect to said rotation axis, and said diametrically opposite positions of said fourth pair of said displacement sensors are angularly displaced by 90 degrees relative to said diametrically opposite positions of said third pair of said displacement sensors;
and
wherein a controlling means is provided for comparing positional displacement amounts measured by said displacement sensors with a corresponding displacement command, and changing the electromagnetic forces of said electromagnetic bearings based on results of the comparison so as to cause agreement between the measured amount and the command.

6 more elements

A method of operating a spindle arrangement for use in holding a workpiece or mounting a work tool on a rotary shaft in a cutting or grinding process, said method comprising the steps of:

rotatably supporting the rotary shaft with radially directed electromagnetic forces of a plurality of electromagnetic bearings;
providing first, second, third and fourth pairs of displacement sensors radially about a rotational axis such that said first and second pairs of said displacement sensors are provided at a first axial location, said third and fourth pairs of said displacement sensors are provided at a second axial location spaced axially away from said first axial location, said first pair of said displacement sensors are located in diametrically opposite positions with respect to said rotation axis, said second pair of said displacement sensors are located in diametrically opposite positions with respect to said rotation axis, said diametrically opposite positions of said second pair of said displacement sensors are angularly displaced by 90 degrees relative to said diametrically opposite positions of said first pair of said displacement sensors, said third pair of said displacement sensors are located in diametrically opposite positions with respect to said rotation axis, said fourth pair of said displacement sensors are located in diametrically opposite positions with respect to said rotation axis, and said diametrically opposite positions of said fourth pair of said displacement sensors are angularly displaced by 90 degrees relative to said diametrically opposite positions of said third pair of said displacement sensors;
measuring amounts of positional displacement of the rotary shaft using said first, second, third and fourth pairs of displacement sensors;
and
comparing positional displacement amounts measured by said displacement sensors with a corresponding displacement command, and changing the electromagnetic forces of said electromagnetic bearings based on results of the comparison so as to cause agreement between the measured amount and the command.

2 more elements

Dependencies are inferred from the claim text.

Facts

Application: 08/141,219Filed 26 Oct 1993
Priority: JP 4-28734226 Oct 1992
Granted: 12 Nov 1996
Term ends: Not estimatedThe source records don’t support an estimate.

Classification14 codes

F16C 32/0444
Active magnetic bearings: details of devices to control the actuation of the electromagnets
B23Q 1/26
Movable or adjustable work or tool supports: characterised by constructional features relating to the co-operation of relatively movable members;…
B23Q 1/70
Members which are comprised in the general build-up of a form of machine, particularly relatively large fixed members: stationary or movable…
B23Q 5/10
Rotary shafts, e.g. working-spindles: driven essentially by electrical means