Device and method of controlling machine tool, to control synchronized operation of spindle axis and feed axis

Patent metadata

Field	Value
Publication number	US-9753452-B2
Application number	US-201514885416-A
Country	US
Kind code	B2
Filing date	Oct 16, 2015
Priority date	Oct 17, 2014
Publication date	Sep 5, 2017
Grant date	Sep 5, 2017

Abstract

A machine tool controller including a numerical control section, a spindle-axis control section and a feed-axis control section. The spindle-axis control section includes a section for making the spindle axis perform an accelerated rotation at maximum capacity from a process start position toward a target thread depth, with a maximum rotation speed set as a target value; a section for detecting a maximum acceleration during the accelerated rotation based on a rotational position; a section for detecting a residual rotation amount from a current position to the target thread depth, based on a total rotation amount and the rotational position; a section for detecting a current speed based on the rotational position; and a section for making the spindle axis perform a decelerated rotation at maximum capacity to reach the target thread depth after the accelerated rotation, based on the maximum acceleration, the residual rotation amount and the current speed.

First claim

The invention claimed is:

1. A controller of a machine tool, configured to control a synchronized operation of a spindle axis and a feed axis, the controller comprising:
a numerical control section configured to prepare a spindle-axis command and a feed-axis command based on a tapping program;
a spindle-axis control section configured to control a rotational motion of the spindle axis in accordance with the spindle-axis command;
a rotation detecting section configured to detect a rotational position of the spindle axis; and
a feed-axis control section configured to control a feed motion of the feed axis in accordance with the feed-axis command, based on the rotational position;
the numerical control section comprising:
a spindle-axis command outputting section configured to obtain, from the tapping program, a total rotation amount and a maximum rotation speed of the spindle axis during a period when the spindle axis operates from a process start position to a target thread depth, and to send the total rotation amount and the maximum rotation speed as the spindle-axis command to the spindle-axis control section;

the spindle-axis control section comprising:
an initial-motion control section configured to make the spindle axis perform an accelerated rotation at maximum capacity using a maximum permissible current of a drive source, from the process start position toward the target thread depth, with the maximum rotation speed set as a target value;
a maximum-acceleration detecting section configured to detect a maximum acceleration during the accelerated rotation at maximum capacity, based on the rotational position;
a residual rotation-amount detecting section configured to detect a residual rotation amount of the spindle axis during a period when the spindle axis operates from a current position to the target thread depth, based on the total rotation amount and the rotational position;
a current-speed detecting section configured to detect a current speed of the spindle axis based on the rotational position; and
a positioning-motion control section configured to make the spindle axis perform a decelerated rotation at maximum deceleration corresponding to the maximum acceleration so as to reach the target thread depth, after the accelerated rotation at maximum capacity, based on the maximum acceleration, the residual rotation amount and the current speed.

2. The controller of claim 1 , further comprising a feed detecting section configured to detect a feed position of the feed axis;
wherein the numerical control section comprises:
a feed-axis command outputting section configured to obtain, from the tapping program, a total feed amount and a thread pitch of the feed axis during a period when the feed axis operates from the process start position to the target thread depth, and to send the total feed amount and the thread pitch as the feed-axis command to the feed-axis control section; and

wherein the feed-axis control section comprises:
a feed-motion control section configured to control the feed motion of the feed axis, based on the thread pitch and the rotational position; and
a residual feed-amount detecting section configured to detect a residual feed amount of the feed axis during a period when the feed axis operates from a current position to the target thread depth, based on the total feed amount and the feed position.

3. The controller of claim 2 , wherein the numerical control section comprises a position recognizing section configured to recognize the current position of the spindle axis based on the residual rotation amount, and also recognize the current position of the feed axis based on the residual feed amount.

4. The controller of claim 2 , wherein the numerical control section comprises a synchronization-error calculating section configured to calculate a synchronization error in the synchronized operation, based on the residual rotation amount, the residual feed amount and the thread pitch.

5. The controller of claim 1 , wherein the positioning-motion control section is configured to make the spindle axis stop at the target thread depth.

6. The controller of claim 5 , wherein the numerical control section is configured to monitor the residual rotation amount and to judge that a tapping process reaches the target thread depth when the residual rotation amount becomes equal to or less than a first predetermined value;
wherein the spindle-axis command outputting section is configured to obtain, from the tapping program, a total return-rotation amount and a maximum return-rotation speed of the spindle axis during a period when the spindle axis operates from the target thread depth to a return completion position, and to send the total return-rotation amount and the maximum return-rotation speed as the spindle-axis command to the spindle-axis control section;
wherein the initial-motion control section is configured to make the spindle axis perform an accelerated inverse rotation at maximum capacity using a maximum permissible current of a drive source, from the target thread depth toward the return completion position, with the maximum return-rotation speed set as a target value;
wherein the maximum-acceleration detecting section is configured to detect a maximum acceleration of inverse rotation during the accelerated inverse rotation at maximum capacity, based on the rotational position;
wherein the residual rotation-amount detecting section is configured to detect a residual return-rotation amount of the spindle axis during a period when the spindle axis operates from a current position to the return completion position, based on the total return-rotation amount and the rotational position;
wherein the current-speed detecting section is configured to detect a current speed of inverse rotation of the spindle axis based on the rotational position; and
wherein the positioning-motion control section is configured to make the spindle axis perform a decelerated inverse rotation at maximum deceleration corresponding to the maximum acceleration of inverse rotation and stop at the return completion position, after the accelerated inverse rotation at maximum capacity, based on the maximum acceleration of inverse rotation, the residual return-rotation amount and the current speed of inverse rotation.

7. The controller of claim 1 , wherein the positioning-motion control section is configured not to make the spindle axis stop at the target thread depth but to make the spindle axis perform an accelerated inverse rotation until the spindle axis reaches a predetermined rotation position, at a maximum acceleration of inverse rotation identical to a maximum deceleration during the decelerated rotation at maximum capacity.

8. The controller of claim 7 , wherein the numerical control section is configured to monitor the residual rotation amount and to judge that a tapping process reaches the target thread depth when the residual rotation amount becomes equal to or less than a first predetermined value;
wherein the spindle-axis command outputting section is configured to obtain, from the tapping program, a total return-rotation amount and a maximum return-rotation speed of the spindle axis during a period when the spindle axis operates from the target thread depth to a return completion position, and to send the total return-rotation amount and the maximum return-rotation speed as the spindle-axis command to the spindle-axis control section;
wherein the initial-motion control section is configured to make the spindle axis perform an accelerated inverse rotation at maximum capacity using a maximum permissible current of a drive source, from the predetermined rotation position toward the return completion position, with the maximum return-rotati

Assignees

• Fanuc Corp

Inventors

• Morita Yuuki
• Okita Tadashi

Classifications

• G05B2219/45215

  Thread cutting · CPC title

• G05B2219/43006

  Acceleration, deceleration control · CPC title

• G05B19/4163 Primary

  Adaptive control of feed or cutting velocity (without NC B23Q15/12) · CPC title

• G05B2219/50226

  Synchronize feed and spindle speed in forward and reverse feed · CPC title

• G05B2219/45216

  Tapping · CPC title