CN112388388B - Machine tool geometric error detection method based on standard ball array - Google Patents

Abstract

The invention relates to the field of machine tool error detection, aims to solve the problem of long time for detecting and identifying the geometric error of the existing machine tool, and provides a machine tool geometric error detection method based on a standard ball array, wherein the ball center positions of a group of standard ball arrays which are measured in advance are compared and calculated with the ball center positions of the standard ball arrays which are detected by a numerical control machine tool measuring head on the machine, and the deviation errors of 6 standard ball array coordinate systems and any 1-15 errors in 15 machine tool geometric errors are detected and identified by using a kinematic homogeneous transformation and a least square method formula; the method comprises the following steps: firstly, establishing a measuring coordinate system with the origin of the coordinate system positioned at the center of a certain sphere in a standard sphere array, the XY plane of the coordinate system parallel to the plane of the standard sphere array and the X axis of the coordinate system parallel or vertical to the edge of a rectangular or rectangular grid formed by the standard sphere array; the other standard ball array sphere center positions are represented by coordinate values of the sphere centers thereof in the measurement coordinate system. The invention has the advantage of short detection period.

Description

Detection method of machine tool geometric error based on standard ball array

technical field

The invention relates to the field of machine tool error detection, in particular to a machine tool geometric error detection method based on a standard ball array.

Background technique

Because the five-axis linkage machine tool has the advantages of better surface adaptability, fewer clamping times and number of fixtures, and higher material removal rate in machining parts with complex surfaces. Therefore, five-axis CNC machine tools are widely used in the processing of turbines, propeller blades and complex aircraft structural parts.

The modern manufacturing industry has higher and higher requirements on the machining accuracy of parts, so the accuracy requirements of CNC machine tools are also higher and higher. Compared with the three-axis linkage machine tool, the rigidity of the five-axis linkage CNC machine tool is reduced, and its geometric accuracy is also reduced. The geometric error compensation of the machine tool is the most effective measure to improve the machining accuracy of the five-axis CNC machine tool, and the premise of the geometric error compensation of the machine tool is to obtain the current geometric error information of the machine tool.

The geometric error of the five-axis CNC machine tool includes the geometric error of the translation axis and the geometric error of the rotary swing axis. The measurement method of the geometric error of the translation axis has been well solved, and there are standard measurement methods in the national standard and ISO standard. In addition, scholars at home and abroad have also proposed 22-line, 14-line, 12-line, and 9-line identification methods based on laser interferometer for the geometric error of translation axis. Traditional methods take a long time to detect and identify geometric errors of machine tools.

SUMMARY OF THE INVENTION

The present invention aims to provide a method for detecting geometric errors of machine tools based on a standard ball array, so as to solve the problem of long time for detection and identification of geometric errors of machine tools in the prior art.

Embodiments of the present invention are implemented as follows:

A method for detecting geometric errors of machine tools based on standard ball arrays, which compares and calculates a set of pre-determined standard ball array ball center positions and the standard ball array ball center positions detected on-machine by a CNC machine tool probe. Detect and identify any 1-15 errors of 6 standard ball array coordinate system deviation errors and 15 machine tool geometric errors;

Among them, 6 standard ball array coordinate system deviation errors include 3 translational deviations and 3 rotational deviations between the standard ball array coordinate system and the CNC machine tool coordinate system; 15 machine tool geometric errors include positioning errors of 3 motion axes, 3 motion errors The verticality error of the axis, the pitch error of the 3 motion axes, the yaw error of the 3 motion axes, and the roll error of the 3 motion axes are as follows:

First, establish that the origin of the coordinate system is located at the center of a sphere in the standard sphere array, the XY plane of the coordinate system is parallel to the plane where the standard sphere array is located, and the X axis of the coordinate system and the rectangle or rectangular grid formed by the standard sphere array are established. A measurement coordinate system with parallel or vertical sides; the position of the center of other standard sphere arrays is represented by the coordinate value of the center of the sphere in this measurement coordinate system;

When the standard ball array is detected on the machine tool, the plane where the standard ball array is located is parallel to the XY plane of the machine tool, and the sides of the rectangle or rectangular grid formed by the standard ball array are parallel or perpendicular to the X axis of the machine tool; When the standard ball array is measured, the measurement coordinate system is the same as the measurement coordinate system when the position of the center of the standard ball array is determined in advance;

In the standard ball array, take the position P ₁ (x ₁ y ₁ z ₁ ) of the center of ball 1 as the origin, take the line connecting the center of ball 1 and the center of ball 2 as the X-axis, and take the center of ball 1 and the center of ball 2 as the X-axis. And the center of the ball 3 is the XY plane to establish a coordinate system, and the direction perpendicular to the XY plane is the Z axis; wherein, the ball 3 is located on the Y axis;

The theoretical position of the center of each standard sphere in the space standard sphere array is recorded as P ₁ (x ₁ y ₁ z ₁ ), P ₂ (x ₂ y ₂ z ₂ ), P ₃ (x ₃ y ₃ z ₃ ), …, P _n-1 (x _n-1 y _n-1 z _n-1 ), P _n (x _n y _n z _n ), where x ₁ =y ₁ =z ₁ =y ₂ =z ₂ =z ₃ =0;

Using the machine tool probe on the machine tool, the center positions of each standard ball are measured as P′ ₁ (x′ ₁ y′ ₁ z′ ₁ ), P′ ₂ (x′ ₂ y′ ₂ z′ ₂ ), P′ ₃ ( x' ₃ y' ₃ z' ₃ ), ..., P' _n-1 (x' _n-1 y' _n-1 z' _n-1 ), P' _n (x' _n y' _n z' _n );

When there is a machine tool error, the actual position p' _a of the machine tool movement is

make:

f=(x+δ _x +zε _y -yε _z +xδ _xx +yδ _yx +zδ _zx +zxε _xy +zyε _yy +zzε _zy -yxε _xz -yyε _yz -yzε _zz -x′) ² +(y+δ _y -zε _x +xε _z +xδ _xy +yδ _yy +zδ _zy -zxε _xx -zyε _yx -zzε _zx +xxε _xz +xyε _yz +xzε _zz -y′) ² +(z+δ _z +yε _x -xε _y +xδ _xz +yδ _yz +zδ _zz +yxε _xx +yyε _yx +yzε _zx -xxε _xy -xyε _yy -xzε _zy -z′) ² ,

得：Depend on

have to:

得：Depend on

have to:

得：Depend on

have to:

得：Depend on

have to:

formula:

δ _x , δ _y , δ _z respectively represent the three translation deviations of the standard ball array coordinate system and the CNC machine tool coordinate system about the X, Y, and Z axes;

ε _x , ε _y , and ε _z represent the three rotational deviations about the X, Y, and Z axes of the standard spherical array coordinate system and the CNC machine tool coordinate system, respectively;

Among the 15 machine tool geometric _errors , _{δ xx} , _{δ yy} , and _{δ zz represent} the positioning errors of the three motion _axes , respectively; ε _xx , ε _xy , ε _xz , ε _yx , ε _yy , ε _yz , ε _zx , ε _zy , ε _zz represent the pitch error of the three motion axes, the yaw error of the three motion axes and the Roll error of each axis of motion;

Solve the equation system composed of the above four groups of equations expressed in matrix form, and calculate the 3 translational deviations, 3 rotational deviations and 15 machine tool geometric errors between the standard spherical array coordinate system and the CNC machine tool coordinate system.

The advantage of using the standard ball array-based machine tool geometric error detection method in this scheme is that the detection period is short, so that this method can not only be used for the detection of machine tool geometric errors in a constant temperature environment, but also for machine tool thermal errors during machining intervals. Tracking detection and identification.

In one embodiment:

The standard ball array is composed of n standard balls, and n≥4.

In one embodiment:

The standard ball array is composed of standard balls arranged on the same plane.

In one embodiment:

The standard ball array is composed of standard ball sub-arrays arranged on different planes parallel to each other.

In one embodiment:

Standard spheres in the same plane are arranged according to rectangular vertices or rectangular grid intersections.

In one embodiment:

In the standard ball array, the sides of the rectangle or rectangular grid formed by the standard ball sub-arrays on different planes are all parallel or perpendicular to each other.

Detailed ways

In addition, if the terms "first", "second" and the like appear in the description of the present invention, they are only used to distinguish the description, and should not be construed as indicating or implying relative importance.

Furthermore, the appearance of the terms "horizontal", "vertical" and the like in the description of the present invention does not mean that the component is required to be absolutely horizontal or overhang, but rather may be slightly inclined. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly inclined.

In the description of the present invention, it should also be noted that, unless otherwise expressly specified and limited, the terms "arranged", "installed", "connected" and "connected" should be understood in a broad sense, for example, it may be a fixed The connection can also be a detachable connection or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, and it can be internal communication between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood in specific situations.

Example

This embodiment proposes a method for detecting geometric errors of machine tools based on standard ball arrays. Calculate, use the formula to detect and identify the deviation error of the 6 standard ball array coordinate system and any 1-15 errors of the 15 machine tool geometric errors;

Among them, 6 standard ball array coordinate system deviation errors include 3 translational deviations and 3 rotational deviations between the standard ball array coordinate system and the CNC machine tool coordinate system; 15 machine tool geometric errors include positioning errors of 3 motion axes, 3 motion errors The verticality error of the axis, the pitch error of the 3 motion axes, the yaw error of the 3 motion axes, and the roll error of the 3 motion axes are as follows:

First, establish that the origin of the coordinate system is located at the center of a sphere in the standard sphere array, the XY plane of the coordinate system is parallel to the plane where the standard sphere array is located, and the X axis of the coordinate system and the rectangle or rectangular grid formed by the standard sphere array are established. A measurement coordinate system with parallel or vertical sides; the position of the center of other standard sphere arrays is represented by the coordinate value of the center of the sphere in this measurement coordinate system;

When the standard ball array is detected on the machine tool, the plane where the standard ball array is located is parallel to the XY plane of the machine tool, and the sides of the rectangle or rectangular grid formed by the standard ball array are parallel or perpendicular to the X axis of the machine tool; When the standard ball array is measured, the measurement coordinate system is the same as the measurement coordinate system when the position of the center of the standard ball array is determined in advance;

In the standard ball array, take the position P ₁ (x ₁ y ₁ z ₁ ) of the center of ball 1 as the origin, take the line connecting the center of ball 1 and the center of ball 2 as the X-axis, and take the center of ball 1 and the center of ball 2 as the X-axis. And the center of the ball 3 is the XY plane to establish a coordinate system, and the direction perpendicular to the XY plane is the Z axis; wherein, the ball 3 is located on the Y axis;

The theoretical position of the center of each standard sphere in the space standard sphere array is recorded as P ₁ (x ₁ y ₁ z ₁ ), P ₂ (x ₂ y ₂ z ₂ ), P ₃ (x ₃ y ₃ z ₃ ), …, P _n-1 (x _n-1 y _n-1 z _n-1 ), P _n (x _n y _n z _n ), where x ₁ =y ₁ =z ₁ =y ₂ =z ₂ =z ₃ =0;

Using the machine tool probe on the machine tool, the center positions of each standard ball are measured as P′ ₁ (x′ ₁ y′ ₁ z′ ₁ ), P′ ₂ (x′ ₂ y′ ₂ z′ ₂ ), P′ ₃ ( x' ₃ y' ₃ z' ₃ ), ..., P' _n-1 (x' _n-1 y' _n-1 z' _n-1 ), P' _n (x' _n y' _n z' _n );

When there is a machine tool error, the actual position p' _a of the machine tool movement is

make:

f=(x+δ _x +zε _y -yε _z +xδ _xx +yδ _yx +zδ _zx +zxε _xy +zyε _yy +zzε _zy -yxε _xz -yyε _yz -yzε _zz -x′) ² +(y+δ _y -zε _x +xε _z +xδ _xy +yδ _yy +zδ _zy -zxε _xx -zyε _yx -zzε _zx +xxε _xz +xyε _yz +xzε _zz -y′) ² +(z+δ _z +yε _x -xε _y +xδ _xz +yδ _yz +zδ _zz +yxε _xx +yyε _yx +yzε _zx -xxε _xy -xyε _yy -xzε _zy -z′) ² ,

得：Depend on

have to:

得：Depend on

have to:

得：Depend on

have to:

得：Depend on

have to:

formula:

δ _x , δ _y , δ _z respectively represent the three translation deviations of the standard ball array coordinate system and the CNC machine tool coordinate system about the X, Y, and Z axes;

ε _x , ε _y , and ε _z represent the three rotational deviations about the X, Y, and Z axes of the standard spherical array coordinate system and the CNC machine tool coordinate system, respectively;

Among the 15 machine tool geometric _errors , _{δ xx} , _{δ yy} , and _{δ zz represent} the positioning errors of the three motion _axes , respectively; ε _xx , ε _xy , ε _xz , ε _yx , ε _yy , ε _yz , ε _zx , ε _zy , ε _zz represent the pitch error of the three motion axes, the yaw error of the three motion axes and the Roll error of each axis of motion;

Solve the equation system composed of the above four groups of equations expressed in matrix form, and calculate the 3 translational deviations, 3 rotational deviations and 15 machine tool geometric errors between the standard spherical array coordinate system and the CNC machine tool coordinate system.

The advantage of using the standard ball array-based machine tool geometric error detection method in this solution is that the detection period is short, so that this method can not only be used for the detection of machine tool geometric errors in a constant temperature environment, but also for machine tool thermal errors during machining intervals. Tracking detection and identification.

In this embodiment, the standard sphere array is composed of n standard spheres and n≥4. Optionally, the standard sphere array is composed of standard spheres arranged on the same plane, and may also be composed of standard sphere sub-arrays arranged on different planes that are parallel to each other.

In this embodiment, the standard spheres located on the same plane are arranged according to rectangular vertices or intersections of rectangular grids. In the standard ball array, the sides of the rectangle or rectangular grid formed by the standard ball sub-arrays on different planes are all parallel or perpendicular to each other.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims (6)

1. A machine tool geometric error detection method based on a standard ball array is characterized in that:

comparing and calculating a group of standard ball array sphere center positions which are measured in advance with standard ball array sphere center positions which are detected by a numerical control machine tool measuring head on machine, and detecting and identifying any 1-15 errors in 6 standard ball array coordinate system deviation errors and 15 machine tool geometric errors by using a formula;

the deviation errors of the 6 standard ball array coordinate systems comprise 3 translation deviations and 3 rotation deviations of the standard ball array coordinate systems and the numerical control machine coordinate system; the geometric errors of the 15 machine tools comprise positioning errors of 3 motion axes, verticality errors of 3 motion axes, pitching errors of 3 motion axes, yaw errors of 3 motion axes and rolling errors of 3 motion axes, and the method comprises the following steps:

firstly, establishing a measuring coordinate system with the origin of the coordinate system positioned at the center of a certain sphere in a standard sphere array, the XY plane of the coordinate system parallel to the plane of the standard sphere array and the X axis of the coordinate system parallel or vertical to the edge of a rectangular or rectangular grid formed by the standard sphere array; the sphere center positions of other standard sphere arrays are represented by the coordinate values of the sphere centers in the measurement coordinate system;

when the standard ball array is detected on a machine tool, the plane of the standard ball array is parallel to the XY plane of the machine tool, and the side of a rectangular or rectangular grid formed by the standard ball array is parallel or vertical to the X axis of the machine tool; when the standard ball array is measured on the machine tool, a measurement coordinate system is consistent with a measurement coordinate system used when the sphere center position of the standard ball array is determined in advance;

with ball 1 center position P in standard ball array₁(x₁ y₁ z₁) Taking a connecting line of the sphere center of the ball 1 and the sphere center of the ball 2 as an original point, taking the sphere center of the ball 1, the sphere center of the ball 2 and the sphere center of the ball 3 as XY planes to establish a coordinate system, and taking a direction vertical to the XY planes as a Z axis; wherein the ball 3 is located on the Y-axis;

recording the psychological position of each standard sphere in the space standard sphere array as P₁(x₁ y₁ z₁)、P₂(x₂ y₂ z₂)、P₃(x₃ y₃z₃)、…、P_n-1(x_n-1 y_n-1 z_n-1)、P_n(x_n y_n z_n) Wherein x is₁＝y₁＝z₁＝y₂＝z₂＝z₃＝0；

Measuring the position of the center of each standard sphere on a machine tool by using a machine tool measuring head to be P₁′(x′₁ y′₁ z′₁)、P′₂(x′₂ y′₂ z′₂)、P′₃(x′₃ y′₃ z′₃)、……、P′_n-1(x′_n-1 y′_n-1 z′_n-1)、P′_n(x′_n y′_n z′_n)；

Actual position p 'of machine tool motion when there is machine tool error'_aIs composed of

Order:

f＝(x+δ_x+zε_y-yε_z+xδ_xx+yδ_yx+zδ_zx+zxε_xy+zyε_yy+zzε_zy-yxε_xz-yyε_yz-yzε_zz-x′)²+(y+δ_y-zε_x+xε_z+xδ_xy+yδ_yy+zδ_zy-zxε_xx-zyε_yx-zzε_zx+xxε_xz+xyε_yz+xzε_zz-y′)²+(z+δ_z+yε_x-xε_y+xδ_xz+yδ_yz+zδ_zz+yxε_xx+yyε_yx+yzε_zx-xxε_xy-xyε_yy-xzε_zy-z′)²，

by

Obtaining:

by

Obtaining:

by

Obtaining:

by

Obtaining:

in the formula:

δ_x、δ_y、δ_zrespectively representing 3 translational deviations of the standard ball array coordinate system and the numerical control machine tool coordinate system about an X, Y, Z axis;

ε_x、ε_y、ε_zrespectively representing 3-term rotation deviation of a standard ball array coordinate system and a numerical control machine tool coordinate system about an X, Y, Z axis;

of the 15-term geometric errors of the machine tool, δ_xx、δ_yy、δ_zzEach represents 3Positioning error of individual axes of motion; delta_xy＝δ_yx、δ_yz＝δ_zy、δ_zx＝δ_xzRespectively representing the perpendicularity errors of 3 motion axes; epsilon_xx、ε_xy、ε_xz,ε_yx、ε_yy、ε_yz,ε_zx、ε_zy、ε_zzRespectively representing the pitching error of 3 motion axes, the yawing error of 3 motion axes and the rolling error of 3 motion axes;

and solving the equation set consisting of the 4 sets of equations expressed in the form of the matrix, and calculating the 3 translation deviations, the 3 rotation deviations and the 15 machine tool geometric errors of the standard spherical array coordinate system and the numerical control machine tool coordinate system.

2. The method for detecting the geometric error of the machine tool based on the standard ball array as claimed in claim 1, wherein the method comprises the following steps:

the standard ball array consists of n standard balls, wherein n is more than or equal to 4.

3. The method for detecting the geometric error of the machine tool based on the standard ball array according to claim 2, is characterized in that:

the standard ball array is composed of standard balls arranged on the same plane.

4. The method for detecting the geometric error of the machine tool based on the standard ball array as claimed in claim 2, wherein the method comprises the following steps:

the standard ball array is composed of standard ball sub-arrays which are respectively arranged on different planes which are parallel to each other.

5. The method for detecting geometric errors of a machine tool based on a standard ball array according to claim 3 or 4, characterized in that:

the standard balls located on the same plane are arranged according to the rectangular vertexes or the rectangular grid intersections.

6. The method for detecting the geometric error of the machine tool based on the standard ball array as claimed in claim 4, wherein the method comprises the following steps:

the sides of the rectangle or the rectangle grid formed by the standard ball sub-arrays on different planes in the standard ball array are all parallel or vertical to each other.