Measuring method and device, machine tool having such device, and work processing method

• US 20020189120A1
• Filed: 06/17/2002
• Published: 12/19/2002
• Est. Priority Date: 10/16/2000
• Status: Active Grant

• Current Assignee: Makino Milling Machine Company Limited
• Original Assignee: Makino Milling Machine Company Limited
• Inventors: Kurahashi, Yasuhiro, Kaneda, Kiyoshi
• Granted Patent: US 6,973,738 B2
• Time in Patent Office: Days
• US Class Current: 33/636
• CPC Class Codes: B23Q 17/22 for indicating or measuring existing or desired position of tool or work B23Q16/005 takes precedence
• CPC Class Codes: G05B 19/042 using digital processors G05B19/05 takes precedence

Abstract

A method of measuring the position of the cutting edge of a tool T mounted to a spindle 14 of an NC machine tool includes steps of measuring the dimension of the center of an end surface of the spindle 14 relative a reference position in a machine coordinate system of the machine tool in the axial directions of the X-, Y- and Z-axes, measuring the dimensions of the position of the cutting edge of the tool T mounted to the spindle 14 relative to the center of the end surface of the spindle 14 in the axial directions of the X-, Y- and Z-axes, obtaining the dimensions of the position of the cutting edge of the tool T mounted to the spindle 14 relative to the reference position in the machine coordinate system through a calculation on the basis of the relative dimensions of the center of the end surface of the spindle 14 in the machine coordinate system and the dimensions of the position of the cutting edge of the tool T mounted to the spindle 14.

Claims

1. A method of measuring the position of a cutting edge of a tool mounted to a spindle of an NC machine tool, comprising the steps of:

measuring the dimension of a reference position of the spindle relative a reference coordinate position of the machine tool in at least an axial direction of the X-, Y- and Z-axes during when the spindle rotates or is stationary after the rotation;

measuring the dimension of the position of a cutting edge of a tool mounted to the spindle relative to the reference position of the spindle in the axial direction when the spindle rotates or is stationary; and

obtaining the dimension of the position of a cutting edge of a tool mounted to the spindle relative to the reference coordinate position through a calculation on the basis of the relative dimensions measured in the previous two steps.

2. A method of measuring the position of a cutting edge of a tool mounted to a spindle of an NC machine tool, comprising the steps of:

measuring the coordinate position in the coordinate system of the machine tool when the reference position of the spindle is positioned at a predetermined position and when the spindle rotates or is stationary after the rotation;

measuring the position of a cutting edge of a tool mounted to the spindle relative to the reference position of the spindle when the spindle rotates or is stationary after the rotation;

obtaining the coordinate position of a cutting edges of the tool mounted in the coordinate system through a calculation on the basis of the relative dimensions measured in the previous two steps.

3. A method of measuring the position of a cutting edge of a tool mounted to a spindle of an NC machine tool, comprising the steps of:

measuring the coordinate position in the coordinate system of the machine tool when the reference position of the spindle is positioned at a predetermined position and when the spindle rotates or is stationary after the rotation;

measuring the position of a cutting edge of a tool mounted to the spindle relative to the reference position of the spindle when the spindle rotates or is stationary after the rotation;

measuring the changes in the position of the reference position of the spindle relative to the spindle housing of the machine tool

obtaining the coordinate position of a cutting edges of the tool mounted in the coordinate system through a calculation on the basis of the relative dimensions measured in the previous three steps.

4. A method of measuring a measurement the coordinate position of a measuring target point of a measuring object in a machine coordinate system by using contacting or non-contacting displacement measuring means, comprising the steps of:

moving the measuring target point of the measuring object into the measurement range of the displacement measuring means by the relative movement between the displacement measuring means and the measuring object along a direction same as a measurable direction of the displacement measuring means;

detecting the output value of the displacement measuring means and the coordinate position in the machine coordinate system at a predetermined measurement timing;

obtaining the coordinate position of the measuring target point of the measuring object in the machine coordinate system relative to the reference position of the displacement measuring means through a calculation on the basis of the detected output value of the displacement measuring means and the coordinate position in the machine coordinate system.

5. A method of measuring the coordinate position of a reference position of a spindle or a reference position of a masterpiece having a known size mounted to a spindle by using contacting or non-contacting displacement measuring means attached to an constitutional member movable relative to the spindle of an NC machine tool, comprising the steps of:

moving the reference position of the spindle or the reference position of the masterpiece attached to the spindle into the measurable range of the displacement measuring means by the relative movement along a direction same as a measurable direction of the displacement measuring means;

detecting the output value of the displacement measuring means and the coordinate position in the machine coordinate system of the NC machine tool at a predetermined measurement timing;

obtaining the coordinate position in the coordinate system of the reference position of the spindle or the reference position of the masterpiece attached to the spindle relative to the reference position of the displacement measuring means through a calculation on the basis of the detected output value of the displacement measuring means and the coordinate position in the machine coordinate system.

6. A method of measuring the coordinate position of a measuring target cutting edge of a tool mounted to a spindle by using contacting or non-contacting displacement measuring means attached to an constitutional member movable relative to the spindle of an NC machine tool, comprising the steps of:

moving the measuring target cutting edge of the tool into the measurable range of the displacement measuring means by the relative movement along a direction same as a measurable direction of the displacement measuring means;

detecting the output value of the displacement measuring means and the coordinate position in the machine coordinate system of the NC machine tool at a predetermined measurement timing;

obtaining the coordinate position in the coordinate system of the measuring target cutting edge of the tool relative to the reference position of the displacement measuring means through a calculation on the basis of the detected output value of the displacement measuring means and the coordinate position in the machine coordinate system.

7. A method of measuring the coordinate position of a measurement point of a workpiece or a reference position of a workpiece fixture movable relative to the spindle side by using contacting or non-contacting displacement measuring means provided on a spindle or a spindle head of an NC machine tool, comprising the steps of:

moving the measurement point of a workpiece or the reference position of the workpiece fixture into the measurable range of the displacement measuring means by the relative movement along a direction same as a measurable direction of the displacement measuring means;

detecting the output value of the displacement measuring means and the coordinate position in the machine coordinate system of the NC machine tool at a predetermined measurement timing;

obtaining the coordinate position in the coordinate system of the measurement point of a workpiece or the reference position of the workpiece fixture relative to the reference position of the displacement measuring means through a calculation on the basis of the detected output value of the displacement measuring means and the coordinate position in the machine coordinate system.

8. A method of measuring the tool length of a tool mounted to a spindle by using contacting or non-contacting displacement measuring means provided a constitutional member movable in Z-axis relative to the spindle of an NC machine tool, the displacement measuring means being capable of measuring the displacement in Z-axis direction, the method comprising the steps of:

moving the reference position of the spindle or a reference position of a masterpiece having a known length and mounted to the spindle into the measurable range of the displacement measuring means by the relative movement;

preliminary detecting the output value of the displacement measuring means and the coordinate position of Z-axis in the machine coordinate system of the NC machine tool at a predetermined measurement timing;

storing the detected value and the value of the length of the masterpiece as calibration data or storing calibration data calculated on the basis of the detected value and the value of the length of the masterpiece;

moving the cutting edges of a tool to be measured, the tool being mounted to the spindle, into the measurable range of the displacement measuring means by the relative movement;

detecting the output value of the displacement measuring means and the coordinate position of Z-axis in the machine coordinate system of the NC machine tool at a predetermined measurement timing;

obtaining the tool length of the tool relative to the reference position of the spindle or the reference position of the masterpiece attached to the spindle through a calculation on the basis of the stored calibration data, the detected output value of the displacement measuring means concerning the tool to be measured and the coordinate position of Z-axis in the machine coordinate system of the NC machine tool.

10. A method of obtaining abrasion loss in the tool length or tool diameter through a calculation on the basis of the difference, before and after a progress of a machining process, in the tool lengths or diameters of the cutting edge, which are obtained by the measuring method according to claim 8 or 9.

12. A method according to any one of claims 4-11, wherein the step of detecting the output value of the displacement measuring means and the coordinate position in the coordinate system at the predetermined timing comprises a step of detecting he output value of the displacement measuring means and the coordinate position in the coordinate system after the relative movement of the displacement measuring means is stopped within the measurement range.

13. A method according to any one of claims 4-11, wherein the step of detecting the output value of the displacement measuring means and the coordinate position in the coordinate system at the predetermined timing comprises a step of detecting he output value of the displacement measuring means and the coordinate position in the coordinate system when the relative movement of the displacement measuring means is executed within the measurement range.

14. A method according to any one of claims 4-13, wherein the coordinate position in the coordinate system detected at the predetermined timing is selected from the value of the indication of a feed shaft position reading means provided on a feed shaft, an NC command value for a feed shaft or a position obtained from an NC command value for a feed shaft added with a position deviation obtained from a servo-control unit.

9. A method of measuring the tool diameter of a tool mounted to a spindle by using contacting or non-contacting displacement measuring means mounted to a constitutional member movable relative to a spindle of an NC machine tool, the displacement measuring means being capable of measuring the displacements in X- and Y-axes directions, the method comprising the steps of:

moving a side face of a masterpiece having a known diameter and mounted to the spindle into the measurable range of the displacement measuring means by the relative movement;

preliminary detecting the output value of the displacement measuring means and the coordinate position of X- or Y-axis in the machine coordinate system of the NC machine tool at a predetermined measurement timing;

storing the detected value and the value of the diameter of the masterpiece as calibration data or storing calibration data calculated on the basis of the detected value and the value of the diameter of the masterpiece;

moving the measurement point of the cutting edges of a tool to be measured, the tool being mounted to the spindle, into the measurable range of the displacement measuring means by the relative movement;

detecting the output value of the displacement measuring means and the coordinate position of X- or Y-axis in the machine coordinate system of the NC machine tool at a predetermined measurement timing;

obtaining the diameter of the cutting edge of the tool through a calculation on the basis of the stored calibration data, the detected output value of the displacement measuring means concerning the tool to be measured and the coordinate position of X- or Y-axis in the machine coordinate system of the NC machine tool.

11. A method of measuring the distance between two measuring surfaces of a workpiece movable relative to a spindle or a spindle head by using contacting or non-contacting displacement measuring means provided on the spindle or the spindle head of an NC machine tool, the displacement measuring means being capable of measuring the displacements in X- and Y-axes directions, the method comprising the steps of:

providing the displacement measuring means so as to be able to measure the displacement in the direction of distance to be measured;

moving the measuring surfaces into the measurable range of the displacement measuring means by the relative movement;

detecting the output value of the displacement measuring means and the coordinate position in the machine coordinate system of the NC machine tool at a predetermined measurement timing;

obtaining the distance between the two surfaces in the workpiece through a calculation on the basis of the detected output values of the displacement measuring means at the two measuring surfaces and the coordinate position.

16. An apparatus for measuring the position of a cutting edge of a tool according to claim 15, wherein the tool cutting edge position measuring means comprises a contacting or non-contacting displacement measuring sensor.

20. An apparatus for measuring according to claim 19, wherein the coordinate position sensor means determines the value of the indication of a feed shaft position reading means provided on a feed shaft, an NC command value for a feed shaft or a position obtained from an NC command value for a feed shaft added with a position deviation obtained from a servo-control unit as the coordinate position of the coordinate system of the relative movement.

15. An apparatus for measuring the position of a cutting edge of a tool mounted to a spindle of an NC machine tool, comprising:

feed shaft position reading means for reading the coordinate position of the coordinate system of the machine tool;

first shaft reference position measuring means, provided on a constitutional member movable relative to the spindle, for measuring the coordinate position of the reference position of the spindle in the coordinate system;

tool cutting edge position measuring means, provided on a constitutional member movable relative to the spindle, for measuring the position of a cutting edge of a tool relative to a reference surface of the spindle; and

calculation means for calculating the coordinate position of the cutting edge of a tool in the coordinate system on the basis of the output values of the feed shaft position reading means, the first shaft reference position measuring means and the tool cutting edge position measuring means.

17. An apparatus for measuring the position of a cutting edge of a tool mounted to a spindle of an NC machine tool, comprising:

feed shaft position reading means for reading the coordinate position of the coordinate system of the machine tool;

position measuring means, provided on a constitutional member movable relative to the spindle, for measuring the coordinate position of the reference position of the spindle in the coordinate system and the position of a cutting edge of a tool relative to the reference position of the spindle; and

calculation means for calculating the coordinate position of the cutting edge of a tool in the coordinate system on the basis of the output values of the feed shaft position reading means and the position measuring means.

18. An apparatus for measuring the position of a cutting edge of a tool mounted to a spindle of an NC machine tool, comprising:

feed shaft position reading means for reading the coordinate position of the coordinate system of the machine tool;

first shaft reference position measuring means, provided on a constitutional member movable relative to the spindle, for measuring the coordinate position of the reference position of the spindle in the coordinate system;

tool cutting edge position measuring means, provided on a constitutional member movable relative to the spindle, for measuring the position of a cutting edge of a tool relative to a reference surface of the spindle;

second shaft reference position measuring means, provided on a spindle housing of the NC machine tool, for measuring the changes in the position of the reference position of the spindle relative to the spindle housing during the rotation; and

calculation means for calculating the coordinate position of the cutting edge of a tool in the coordinate system on the basis of the output values of the feed shaft position reading means, the first shaft reference position measuring means, the tool cutting edge position measuring means and the first shaft reference position measuring means.

19. An apparatus for measuring the coordinate position of measuring surface of a target by using the displacement measuring means, comprising:

contacting or non-contacting displacement measuring means which can measure the displacement at least one axial direction of X-, Y- and Z-axis;

coordinate position sensor means for detecting the coordinate position of the coordinate system of the relative movement between the measuring target point of the measuring object the displacement measuring means; and

calculating means for obtaining the coordinate position in the coordinate system of the measuring target point of the measuring object relative to the reference position of the displacement measuring means through a calculation on the basis of the output value of the displacement measuring means and the output value of the coordinate position sensor means at a predetermined measurement timing after the measuring target point of the measuring object is moved into the measurable range of the displacement measuring means by the relative movement along a direction same as a measurable direction of the displacement measuring means.

21. A machine tool for machining a workpiece with a numerically controlled relative movement between a spindle to which a tool is mounted and a table to which <

the workpiece is fixed, comprising;

feed shaft position reading means for reading the coordinate position of the coordinate system of the machine tool;

first shaft reference position measuring means, provided on a constitutional member movable relative to the spindle, for measuring the coordinate position of the reference position of the spindle in the coordinate system;

tool cutting edge position measuring means, provided on a constitutional member movable relative to the spindle, for measuring the position of a cutting edge of a tool relative to a reference surface of the spindle;

calculation means for calculating the coordinate position of the cutting edge of a tool in the coordinate system on the basis of the output values of the feed shaft position reading means, the first shaft reference position measuring means and the tool cutting edge position measuring means; and

correcting means for correcting the numeric control command on the basis of the coordinate position of the cutting edge of a tool in the coordinate system calculated by the calculating means.

22. A machine tool for machining a workpiece with a numerically controlled relative movement between a spindle to which a tool is mounted and a table to which the workpiece is fixed, comprising:

feed shaft position reading means for reading the coordinate position of the coordinate system of the machine tool;

first shaft reference position measuring means, provided on a constitutional member movable relative to the spindle, for measuring the coordinate position of the reference position of the spindle in the coordinate system;

tool cutting edge position measuring means, provided on a constitutional member movable relative to the spindle, for measuring the position of a cutting edge of a tool relative to a reference surface of the spindle;

workpiece reference position measuring means for measuring the coordinate position of the reference position of the workpiece in the coordinate system;

calculation means for calculating the position of a cutting edge of a tool relative to the reference position of the workpiece on the basis of the output values of the feed shaft position reading means, the first shaft reference position measuring means and the tool cutting edge position measuring means; and

correcting means for correcting the numeric control command on the basis of the position of a cutting edge of a tool relative to the reference position of the workpiece calculated by the calculating means.

23. A machine tool for machining a workpiece with a numerically controlled relative movement in three axial directions of X-, Y- and Z-axes between a spindle to which a tool is mounted and a table to which the workpiece is fixed, comprising:

contacting or non-contacting displacement measuring means which can measure the displacement of a measuring target point of the spindle, the tool or the workpiece at least one axial direction of X-, Y- and Z-axis;

coordinate position sensor means for detecting the coordinate position of the coordinate system of the relative movement between the measuring target point the displacement measuring means; and

calculating means for detecting the output value of the displacement measuring means and the output value of the coordinate position sensor means at a predetermined measurement timing after the measuring target point of the measuring object is moved into the measurable range of the displacement measuring means by the relative movement along a direction same as a measurable direction of the displacement measuring means to obtain the coordinate position in the coordinate system of the measuring target point relative to the reference position of the displacement measuring means through a calculation on the basis of the detected output values.

24. A method of machining a workpiece into a desired shape with an NC machine tool which numerically controls the relative movement between a spindle to which a tool is mounted and a table to which the workpiece is fixed relatively to each other, the method comprising the steps of:

measuring the coordinate position in the machine coordinate system when a reference position of the spindle is positioned at a predetermined position and when the spindle rotates or is stationary after the rotation;

measuring the position of a cutting edge of a tool mounted to the spindle relative to the reference position of the spindle when the spindle rotates or is stationary;

obtaining the coordinate position of the cutting edges of the tool in the coordinate system through a calculation on the basis of the values measured in the previous two steps; and

obtaining a correction for the numeric control command for machining the workpiece on the basis of the coordinate position of the cutting edge of the tool mounted to the spindle in the coordinate system.

25. A method of machining a workpiece into a desired shape with an NC machine tool which numerically controls the relative movement in three axial directions of X-, Y- and Z-axes between a spindle to which a tool is mounted and a table to which the workpiece is fixed relatively to each other, the method comprising the steps of:

moving the measuring target point of the spindle, the tool or the workpiece into the measurement range of the displacement measuring means through the relative movement by using contacting or non-contacting displacement measuring means along a direction same as a measurable direction of the displacement measuring means;

detecting the output value of the displacement measuring means and the coordinate position in the coordinate system of the relative movement at a predetermined measurement timing;

obtaining the coordinate position of the measuring target point in the coordinate system relative to the reference position of the displacement measuring means through a calculation on the basis of the detected output value and the coordinate position of the coordinate system to machine the workpiece.

26. A tool presetter for measuring and registering the tool length of diameter of the cutting edges of a tool mounted to a spindle of an NC machine tool, comprising:

displacement measuring means which is movable relative to a tool mounting portion and capable of measuring the displacements in X-, Y- and X-axial directions;

feed shaft position reading means for reading the coordinate position of the coordinate system of the relative movement;

calculating means for detecting the output value of the displacement measuring means and the output value of displacement measuring means at a predetermined measurement timing after a reference position of a masterpiece having a known size mounted to the tool mounting portion, the cutting edge of the tool mounted to the tool mounting portion or the outermost side surface of the tool is moved into the measurable range of the displacement measuring means by the relative movement and for obtaining the coordinate position in the coordinate system of the reference position of the masterpiece, the cutting edges of the tool or the outermost side surface of the tool on the basis of the detected output values and the value of the size of the masterpiece and for calculating the tool length or tool diameter of the tool.