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

Patent metadata

Field	Value
Publication number	US-10065255-B2
Application number	US-201615217058-A
Country	US
Kind code	B2
Filing date	Jul 22, 2016
Priority date	Jul 29, 2015
Publication date	Sep 4, 2018
Grant date	Sep 4, 2018

Abstract

A controller for controlling a synchronized operation of spindle and feed axes. A spindle-axis control section includes an initial-motion control section for making a spindle axis perform an accelerated rotation at maximum capacity from a process start position; a maximum-acceleration detecting section for detecting a maximum acceleration of the spindle axis; a residual rotation-amount detecting section for detecting a residual rotation amount of the spindle axis; a current-speed detecting section for detecting a current speed of the spindle axis; a positioning-motion control section for making the spindle axis perform a decelerated rotation so as to reach the target thread depth after the accelerated rotation; and an overshoot detecting section for detecting an overshoot of the spindle axis during the decelerated rotation.

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, by a velocity control in which the maximum rotation speed is set as a target value;
a maximum-acceleration detecting section configured to detect a maximum acceleration of the spindle axis 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;
a positioning-motion control section configured to execute a position control for making the spindle axis perform a decelerated rotation 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; and
an overshoot detecting section configured to detect an overshoot of the spindle axis relative to the target thread depth during the decelerated rotation, based on the residual rotation amount.

2. The controller of claim 1 , 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 or from an initial return position at which the spindle axis has returned by a predetermined rotation number from the target thread depth, by a velocity control in which the maximum return-rotation speed is set as a target value;
wherein the maximum-acceleration detecting section is configured to detect or obtain a maximum acceleration of inverse rotation of the spindle axis during a period when the spindle axis performs the accelerated inverse rotation from the target thread depth;
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;
wherein the positioning-motion control section is configured to execute a position control for making the spindle axis perform a decelerated 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; and
wherein the overshoot detecting section is configured to detect an overshoot of the spindle axis relative to the return completion position during the decelerated inverse rotation, based on the residual return-rotation amount.

3. The controller of claim 1 , wherein the positioning-motion control section is configured to monitor the overshoot detected by the overshoot detecting section, and at a moment when it is judged that the overshoot exceeds a predetermined permissible value, to set a position command for the spindle axis at zero and thereby stop the spindle axis.

4. The controller of claim 1 , wherein the positioning-motion control section is configured to monitor the overshoot detected by the overshoot detecting section, and at a moment when it is judged that the overshoot relative to the target thread depth exceeds a predetermined permissible value, to provide the spindle axis with a command for making the spindle axis perform a reverse motion until the target thread depth or a position at the moment of judgment that the overshoot exceeds the permissible value, and thereby stop the spindle axis when the reverse motion is completed.

5. The controller of claim 2 , wherein the positioning-motion control section is configured to monitor the overshoot detected by the overshoot detecting section, and at a moment when it is judged that the overshoot relative to the return completion position exceeds a predetermined permissible value, to provide the spindle axis with a command for making the spindle axis perform a reverse motion until the return completion position or a position at the moment of judgment that the overshoot exceeds the permissible value, and thereby stop the spindle axis when the reverse motion is completed.

6. The controller of claim 3 , wherein the feed-axis control section is configured to control the feed motion of the feed axis with use of the rotational position of the spindle axis, during a period from the moment when the positioning-motion control section judges that the overshoot exceeds the permissible value until the instant when the positioning-motion control section stops the spindle axis.

7. 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 return-rotation amount and a maximum return-rotation speed of the spindle axis during a period when the spindle axis operates from a target thread depth to a return completion position, and to send the total return-rotati

Assignees

• Fanuc Corp

Inventors

• Morita Yuuki
• Okita Tadashi
• Tajima Daisuke

Classifications

• G05B2219/50232

  Synchronize change of feed and spindle speed when overriding feed speed · CPC title

• B23G1/32 Primary

  by milling · CPC title

• G05B19/4163 Primary

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

• B23G1/16

  in holes of workpieces by taps (B23G1/26, B23G1/32, B23G1/36 take precedence) · CPC title

• G05B19/4141

  characterised by a controller or microprocessor per axis · CPC title