DEVICE AND METHOD OF CONTROLLING MACHINE TOOL, TO CONTROL SYNCHRONIZED OPERATION OF SPINDLE AXIS AND FEED AXIS

• US 20170028490A1
• Filed: 07/22/2016
• Published: 02/02/2017
• Est. Priority Date: 07/29/2015
• Status: Active Grant

• Current Assignee: Fanuc Corporation
• Original Assignee: Fanuc Corporation
• Inventors: MORITA, Yuuki, OKITA, Tadashi, TAJIMA, Daisuke
• Granted Patent: US 10,065,255 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B23G 1/16 in holes of workpieces by taps B23G1/26, B23G1/32, B23G1/36 take precedence
• CPC Class Codes: B23G 1/32 by milling
• CPC Class Codes: G05B 19/4141 characterised by a controller or microprocessor per axis
• CPC Class Codes: G05B 19/416 characterised by control of velocity, acceleration or deceleration G05B19/19 takes precedence
• CPC Class Codes: G05B 2219/49108 Spindle speed
• CPC Class Codes: G05B 2219/50232 Synchronize change of feed and spindle speed when overriding feed speed

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.

Claims

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 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 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-rotation amount and the maximum return-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 inverse rotation at maximum capacity 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;

a maximum-acceleration detecting section 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;

a residual rotation-amount detecting section 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;

a current-speed detecting section configured to detect a current speed of inverse rotation 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 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

an overshoot detecting section 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.

8. A method of controlling a machine tool, configured to control a synchronized operation of a spindle axis and a feed axis, the method comprising the steps, executed by a controller, of:

obtaining, from a 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;

making the spindle axis perform an accelerated rotation at maximum capacity from the process start position, by a velocity control in which the maximum rotation speed is set as a target value;

detecting a maximum acceleration of the spindle axis during the accelerated rotation at maximum capacity, based on a rotational position feedback of the spindle axis;

detecting 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 feedback;

detecting a current speed of the spindle axis based on the rotational position feedback;

executing 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

detecting an overshoot of the spindle axis relative to the target thread depth during the decelerated rotation, based on the residual rotation amount.

9. A method of controlling a machine tool, configured to control a synchronized operation of a spindle axis and a feed axis, the method comprising the steps, executed by a controller, of:

obtaining, from a 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;

making the spindle axis perform an accelerated inverse rotation at maximum capacity 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;

detecting or obtaining 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;

detecting 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 a rotational position feedback of the spindle axis;

detecting a current speed of inverse rotation of the spindle axis based on the rotational position feedback;

executing 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

detecting an overshoot of the spindle axis relative to the return completion position during the decelerated inverse rotation, based on the residual return-rotation amount.

10. The method of claim 8, further comprising the step, executed by a controller, of monitoring the overshoot and, at an instant when the overshoot exceeds a predetermined permissible value, stopping the spindle axis.