Numerical control device and numerical control method

Patent metadata

Field	Value
Publication number	US-10698381-B2
Application number	US-201816045948-A
Country	US
Kind code	B2
Filing date	Jul 26, 2018
Priority date	Jul 27, 2017
Publication date	Jun 30, 2020
Grant date	Jun 30, 2020

Abstract

A numerical control method at least controls a spindle motor of a machine tool so as to perform machining in accordance with machining conditions. In the method, vibration occurring in a tool is acquired with a vibration acquisition unit, and the machining on a workpiece performed by a machining control unit is stopped when vibration having a predetermined amplitude or greater occurs in the tool. Based on state data indicating the state of the spindle motor at that time, multiple compensation plans for compensating the state of the spindle motor in order to suppress vibration occurring in the tool are calculated. The thus calculated multiple compensation plans are displayed on a display unit together with the state of the spindle motor at the time of occurrence of vibration having the predetermined amplitude or greater in the tool.

First claim

What is claimed is:

1. A numerical control device for controlling a machine tool configured to machine a workpiece with a tool attached to a spindle by moving the tool and the workpiece relatively to each other, in accordance with machining conditions, comprising:
a machining control unit configured to at least control a spindle motor of the machine tool so as to perform machining in accordance with the machining conditions;
a vibration acquisition unit configured to acquire vibration occurring in the tool;
a machining stopping unit configured to stop the machining on the workpiece performed by the machining control unit when vibration of a predetermined amplitude or greater occurs in the tool;
a state acquisition unit configured to acquire state data indicating a state of the spindle motor configured to rotate the spindle;
a compensation plan calculating unit configured to calculate, based on the state data, multiple compensation plans for compensating the state of the spindle motor in order to suppress vibration occurring in the tool when vibration of the predetermined amplitude or greater occurs in the tool; and
a display control unit configured to cause a display unit to display the state of the spindle motor at a time of occurrence of vibration having the predetermined amplitude or greater in the tool, together with the calculated multiple compensation plans, when vibration of the predetermined amplitude or greater has occurred in the tool.

2. The numerical control device according to claim 1 , wherein the compensation plan calculating unit is configured to calculate at least two compensation plans, among six compensation plans including two compensation plans in which output of the spindle motor is kept same as output of the spindle motor at the time of occurrence of vibration having the predetermined amplitude or greater in the tool, two compensation plans in which loss of the spindle motor is kept same as loss of the spindle motor at the time of occurrence of vibration having the predetermined amplitude or greater in the tool, and two compensation plans in which torque of the spindle motor is kept same as torque of the spindle motor at the time of occurrence of vibration having the predetermined amplitude or greater in the tool.

3. The numerical control device according to claim 2 , wherein the compensation plan calculating unit is configured to calculate the two compensation plans in which the loss of the spindle motor is kept the same as the loss of the spindle motor at the time of occurrence of vibration having the predetermined amplitude or greater in the tool, based on the state data and data concerning loss of the spindle motor.

4. The numerical control device according to claim 1 , wherein the state of the spindle motor includes a rotational speed of the spindle motor and a torque of the spindle motor.

5. The numerical control device according to claim 1 , further comprising:
a machining condition changing unit configured to change the machining conditions so as to shift the state of the spindle motor by a given amount from the state of the spindle motor at a time when vibration of the predetermined amplitude or greater has been detected, in accordance with the compensation plan selected by an operator, within a usable range of the tool and within an output permissible range within which the spindle motor is permitted to produce output; and
a trial machining control unit configured to perform trial machining on the workpiece, based on the changed machining conditions.

6. The numerical control device according to claim 5 , further comprising a machining restarting unit configured to restart machining on the workpiece by the machining control unit with the machining conditions changed by the machining condition changing unit, in a case where no vibration of the predetermined amplitude or greater occurs in the tool or in a case where an instruction is given by the operator, when the trial machining is performed by the trial machining control unit.

7. The numerical control device according to claim 5 , wherein the display control unit is configured to, when the compensation plan is selected by the operator, shift the currently displayed state of the spindle motor by a given amount along the selected compensation plan, within the usable range of the tool and within the output permissible range within which the spindle motor is permitted to produce output.

8. The numerical control device according to claim 1 , further comprising:
a machining condition changing unit configured to change the machining conditions so as to shift the state of the spindle motor by a given amount from the state of the spindle motor at a time when vibration of the predetermined amplitude or greater has been detected, in accordance with the compensation plan selected by an operator, within a usable range of the tool and within an output permissible range within which the spindle motor is permitted to produce output; and
a machining restarting unit configured to restart machining on the workpiece by the machining control unit, with the changed machining conditions.

9. The numerical control device according to claim 8 , wherein the display control unit is configured to, when the compensation plan is selected by the operator, shift the currently displayed state of the spindle motor by a given amount along the selected compensation plan, within the usable range of the tool and within the output permissible range within which the spindle motor is permitted to produce output.

10. A numerical control method for controlling a machine tool configured to machine a workpiece with a tool attached to a spindle by moving the tool and the workpiece relatively to each other, in accordance with machining conditions, comprising:
a machining control step of at least controlling a spindle motor of the machine tool so as to perform machining in accordance with the machining conditions;
a vibration acquisition step of acquiring vibration occurring in the tool;
a machining stopping step of stopping the machining on the workpiece performed in the machining control step when vibration of a predetermined amplitude or greater occurs in the tool;
a state acquisition step of acquiring state data indicating a state of the spindle motor configured to rotate the spindle;
a compensation plan calculating step of calculating, based on the state data, multiple compensation plans for compensating the state of the spindle motor in order to suppress vibration occurring in the tool when vibration of the predetermined amplitude or greater occurs in the tool; and
a display control step of causing a display unit to display the state of the spindle motor at a time of occurrence of vibration having the predetermined amplitude or greater in the tool, together with the calculated multiple compensation plans, when vibration of the predetermined amplitude or greater has occurred in the tool.

11. The numerical control method according to claim 10 , the compensation plan calculating step calculates at least two compensation plans, among six compensation plans including two compensation plans in which output of the spindle motor is kept same as output of the spindle motor at the time of occurrence of vibration having the predetermined amplitude or greater in the tool, two compensation plans in which loss of the spindle motor is kept same as loss of the spindle motor at the time of occurrence of vibration having the predetermined amplitude or greater in the tool, and two compensation plans in which torque of the spindle motor is kept same as torque of the spindle motor at the time of occurrence of vibration having the predetermined amplitude or greater in the too

Assignees

• Fanuc Corp

Inventors

• Kamiya Yohei

Classifications

• G05B2219/41115

  Compensation periodical disturbance, like chatter, non-circular workpiece · CPC title

• G05B2219/35026

  Design of machine tool, of cnc machine · CPC title

• G05B19/404 Primary

  characterised by control arrangements for compensation, e.g. for backlash, overshoot, tool offset, tool wear, temperature, machine construction errors, load, inertia (G05B19/19, G05B19/41 take precedence) · CPC title

• G05B19/414 Primary

  Structure of the control system, e.g. common controller or multiprocessor systems, interface to servo, programmable interface controller · CPC title

• G05B2219/41116

  Compensation for instability · CPC title