# US 7,194,329 B2 · Numerical control apparatus and numerical control system

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- Number: US 7,194,329 B2
- Document ID: US7194329B2
- Status: Granted
- Kind: B2
- Application number: 11/289,531
- Filed: 2005-11-30
- Published: 2006-06-22
- Granted: 2007-03-20
- Earliest claimed: 2004-12-01
- Assignees: Mitsubishi Denki Kabushiki Kaisha; Yamazaki Mazak Corporation
- Inventors: Tomonori Sato; Eiji Hayashi; Yuji Mizukami; Toshiyuki Muraki; Akira Iseki
- Web page: https://patentgrep.com/patent/US7194329B2

## CPC

- G05B 19/19: characterised by positioning or contouring control systems, e.g. to control position from one programmed point to another or to control movement along a programmed continuous path
- G05B 2219/49135: Active clamping, use servo to keep in position
- G05B: CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS (systems for controlling or regulating non-electric variables G05D; systems for regulating electric or magnetic variables G05F; control devices or systems insofar as characterised by mechanical features only G05G)

## Abstract

An NC apparatus controls a position of a tool by driving a plurality of shafts with a plurality of servomotors. The shafts includes at least one clamp shaft that can be mechanically clamped or non-clamped. A clamp determining unit determines whether a state of the clamp shaft and outputs a signal based on the state. A correcting unit corrects a position instruction value or a position detection value of at least one shaft other than the clamp shaft based on the signal and a correction value so as to cancel an error in a position of the tool due to movement of the tool performed by the clamp shaft.

## Claims

### Claim 1

A numerical control apparatus including a position instruction generating unit that generates and outputs a plurality of position instruction values indicative of a position of a tool of a numerical control machine tool, a plurality of servo controllers each of which controls a corresponding one of a plurality of servomotors in the numerical control machine tool based on a corresponding one of the position instruction values, and a plurality of detectors each of which detects a rotational position of a corresponding one of the servomotors and feeds back a position detection value indicative of detected rotational position to a corresponding one of the servo controllers, each of the servomotors driving a corresponding one of a plurality of shafts, at least one of the shafts being a clamp shaft that can be mechanically clamped and non-clamped, the numerical control apparatus further comprising:
a clamp determining unit that determines a state of the clamp shaft, the state including a clamping state in which the clamp shaft is clamped and a non-clamping state in which the clamp shaft is non-clamped, and outputs a clamp state signal indicative of the state of the clamp shaft; and
a correcting unit that corrects at least one of a position instruction value and a position detection value corresponding to at least one shaft other than the clamp shaft based on the clamp state signal and a correction value so as to cancel an error in a position of the tool due to a movement of the tool performed by the clamp shaft.

### Claim 2 (depends on 1)

The numerical control apparatus according to claim 1, wherein the correcting unit corrects at least one of the position instruction value and the position detection value so as to cancel an error in the position of the tool in a direction different from a direction of movement of the tool performed by the clamp shaft.

### Claim 3 (depends on 1)

The numerical control apparatus according to claim 1, wherein the correcting unit includes
a clamp correcting unit that corrects at least one of the position instruction value and the position detection value when the clamp state signal indicates that the clamp shaft is in the clamping state; and
a non-clamp correcting unit that corrects at least one of the position instruction value and the position detection value when the clamp state signal indicates that the clamp shaft is in the non-clamping state.

### Claim 4 (depends on 3)

The numerical control apparatus according to claim 3, wherein the non-clamp correcting unit corrects at least one of the position instruction value and the position detection value of the clamp shaft so as to cancel an error in the position of the tool in a direction of movement of the tool performed by the clamp shaft.

### Claim 5 (depends on 3)

The numerical control apparatus according to claim 3, wherein the clamp correcting unit corrects at least one of the position instruction value and the position detection value of at least one shaft other than the clamp shaft so as to cancel an error in the position of the tool in a direction of movement of the tool performed by the clamp shaft.

### Claim 6

A numerical control machine tool comprising:
a workpiece holding apparatus configured to hold a workpiece;
a tool configured to machine the workpiece;
a machining head configured to hold the tool;
a plurality of shafts configured to be controlled by the workpiece holding apparatus and the machining head so as to move the workpiece and the tool in different directions, the shafts including a clamp shaft;
a plurality of servomotors each of which drives a corresponding one of the shafts;
a clamp apparatus that mechanically clamps the clamp shaft; and
a numerical control apparatus including
a position instruction generating unit that generates and outputs a plurality of position instruction values indicative of a position of a tool of a numerical control machine tool;
a plurality of servo controllers each of which controls a corresponding one of a plurality of servomotors in the numerical control machine tool based on a corresponding one of the position instruction values;
a plurality of detectors each of which detects a rotational position of a corresponding one of the servomotors and feeds back a position detection value indicative of detected rotational position to a corresponding one of the servo controllers, each of the servomotors driving a corresponding one of a plurality of shafts, at least one of the shafts being a clamp shaft that can be mechanically clamped and non-clamped;
a clamp determining unit that determines a state of the clamp shaft, the state including a clamping state in which the clamp shaft is clamped and a non-clamping state in which the clamp shaft is non-clamped, and outputs a clamp state signal indicative of the state of the clamp shaft; and
a correcting unit that corrects at least one of a position instruction value and a position detection value corresponding to at least one shaft other than the clamp shaft based on the clamp state signal and a correction value so as to cancel an error in a position of the tool due to a movement of the tool performed by the clamp shaft.