CN104308657A - Machine tool rotating shaft geometry error six-circle identifying method based on measuring of ball bar instrument - Google Patents

Abstract

The invention discloses a machine tool rotating shaft geometry error six-circle identifying method based on measuring of a ball bar instrument. The method comprises the following steps of determining six measuring positions of the ball bar instrument according to the type and position of a machine tool rotating shaft, obtaining the relation of the readings of the ball bar instrument at all positions and the geometry error of the rotating shaft according to the influence of the geometry error of the rotating shaft to the machine tool precision and in combination with the direction of the ball bar instrument at six measuring positions, obtaining an identifying matrix M of the geometry error of the rotating shaft, by combining each geometry error definition of the rotating shaft, obtaining an identifying formula of the geometry error of the rotating shaft, selecting appropriate coordinates for the six measuring positions to install the ball bar instrument, operating corresponding machine tool codes, obtaining the corresponding readings of the ball bar instrument at the six positions of the rotating shaft, substituting the readings of the ball bar instrument and the measuring position coordinates into the identifying formula of the geometry error of the rotating shaft, and obtaining all 10 geometry errors of each rotating shaft. The method is suitable for the rotating shafts in different types without principle error, the system entry is good, the measuring is convenient, and the identifying precision is high.

Description

A kind of rotary axis of machine tool geometric error six measured based on ball bar encloses discrimination method

Technical field

The present invention relates to Digit Control Machine Tool design field, particularly relate to a kind of rotary axis of machine tool geometric error six measured based on ball bar and enclose discrimination method.

Background technology

Along with requirement on machining accuracy and workpiece complexity promote, the ratio of five-axle number control machine tool shared by manufacturing industry is increasing.On workpiece quality impact greatly, it is the major criterion of a measurement lathe to the machining accuracy of lathe.Geometric error is reproducible, stablizes constant, so be easy to the compensation realizing geometric error, improve the machining accuracy of lathe in for a long time.

Geometric Error for Computerized Numerical Control Milling Machine model is the basis of geometric error compensation, and these models can be used for predicting and compensating the geometric error of lathe, but prerequisite is exactly each geometric error item in model needs to measure identification and obtain.The discrimination method comparative maturity of 21 geometric errors of three axle lathes, also there is a lot of method and apparatus both at home and abroad in the measurement for the rotating shaft error of five-axle number control machine tool, device mainly contains 3D probe, ball bar, R-test, wherein the most generally uses with ball bar.Chinese scholars proposes a lot of discrimination method based on ball bar measurement.

(1) Zagarbashi S.H.H. and the Mayer J.R.R. five kinds of test phases proposed based on ball bar carry out the geometric error of identification lathe A axle, and the method only needs the independent rotary motion of A axle.(see Zargarbashi SHH, Mayer JRR (2006) Assessment of machine tool trunnion axis motion error, using magnetic double ball bar, International Journal of Machine Tools and Manufacture 46 (14): 1823-1834).But the method identification obtains 5 geometric errors of A axle, cannot obtain all error term.The method and lathe in addition

(2) people such as Kwang-II Lee uses ball bar to propose five kinds of test paths for C axle, and C axle geometric error item parametrization is represented to come that identification obtains geometric error item.(see Lee KI, Lee DM, Yang SH (2012) Parametric modeling and estimation of geometric errors for a rotary axis using double ball-bar.International Journal of Advanced Manufacturing Technology 62 (5-8): 741-750).But the method is easy for C axle, is not suitable for other types rotating shaft.

(3) people such as He Gaiyun proposes a kind of five-axis machine tool error detection method, and the method realizes special curve movement by lathe five-axle linkage, and is combined identification rotating shaft error with error model.(see He Gaiyun, Guo Longzhen, Liu Xin, Liu Peipei, the Five-axis NC Machining Center accuracy checking method of a kind of pair of turntable structure, 2013 years, publication number was CN102944197A).But the method is relevant with machine tool structure and machine tool error model, and is not suitable for all types of five-axis machine tool.

The discrimination method of three axis numerically controlled machine 21 geometric errors has 9 collimation methods based on laser interferometer, 12 collimation methods, 21 collimation methods, the body diagonal method of fractional steps etc., wherein 9 line measurement line numbers are few, and it is convenient to measure, systematicness is good, and without the errors of principles, is applicable to different three axis numerically controlled machines.As not convenient in this measurement of 9 collimation method in rotating shaft measuring method, the discrimination method being suitable for different rotary axle had nothing to do with machine tool error model.

Current detection method is how relevant with machine tool error model, is generally only applicable to the identification of certain concrete rotating shaft simultaneously, does not have versatility.

Summary of the invention

The object of the invention is to propose a kind of rotary axis of machine tool geometric error six measured based on ball bar and enclose discrimination method, realize the identification of rotating shaft geometric error in conjunction with ball bar measuring characteristic.This invention is not only suitable for dissimilar rotating shaft, and measures quick and convenient, and systematicness is good, without original reason error.

The rotary axis of machine tool geometric error six measured based on ball bar encloses a discrimination method, comprises the steps:

Step 1, according to rotary axis of machine tool type and position, determine six measuring positions of ball bar;

Step 2, according to rotating shaft geometric error, machine tool accuracy to be affected, and in conjunction with ball bar direction, six measuring positions place, obtain each measuring position place ball bar reading and rotating shaft geometric error relation, and then obtain rotating shaft geometric error discernibility matrixes M;

Step 3, utilize rotating shaft geometric error discernibility matrixes M and in conjunction with each geometric error of rotating shaft definition, obtain rotating shaft geometric error item identification formula;

Step 4, select suitable coordinate to install ball bar to six measuring positions, run corresponding lathe code, obtain rotating shaft in each position corresponding ball bar reading;

Step 5, bring ball bar reading and measuring position coordinate into rotating shaft geometric error identification formula, obtain 10 geometric errors that each rotating shaft is all;

According to rotary axis of machine tool particular type and position in step 1, determine six measuring positions of ball bar under rotating shaft coordinate system, comprise step:

Step 1.1, determine rotary axis of machine tool type: A axle, B axle and C axle, according to machine tool structure and rotary shaft position setting rotating shaft coordinate system;

Step 1.2, determine ball bar six measuring positions under rotating shaft coordinate system, comprise astrosphere position on ball bar direction and ball bar, specific as follows:

Ball bar direction, position 1 place is parallel with rotating shaft coordinate system x-axis direction, and astrosphere coordinate is [0,0, z ₁]; Ball bar direction, position 2 place is parallel with rotating shaft coordinate system y-axis direction, and astrosphere coordinate is [0,0, z ₁]; Position 3 place ball bar overlaps with rotating shaft coordinate system z-axis, and astrosphere coordinate is [0,0, z ₁]; Ball bar direction, position 4 place is parallel with rotating shaft coordinate system x-axis direction, and astrosphere coordinate is [0, y ₄, z ₁]; Ball bar direction, position 5 place is parallel with rotating shaft coordinate system x-axis direction, and astrosphere coordinate is [0,0, z ₅]; Ball bar direction, position 6 place is parallel with rotating shaft coordinate system y-axis direction, and astrosphere coordinate is [0,0, z ₅].

Further, obtain rotating shaft geometric error discernibility matrixes M in conjunction with ball bar direction, six measuring positions and coordinate in step 2 and comprise step:

Step 2.1, according to lathe geometric error model, obtaining rotating shaft geometric error affects expression formula to machine tool accuracy, in order to identification is convenient, just brings basic for rotating shaft geometric error item into lathe geometric error model, ignores the impact of linear axes error.Simultaneously lathe geometric error model should be transformed into and measure under rotating shaft coordinate system to improve identification precision; Also the definition of rotating shaft geometric error item directly can be utilized in addition to obtain rotating shaft geometric error expression formula is affected on machine tool accuracy; On dissimilar lathe, to affect expression formula to machine tool accuracy consistent for the geometric error of identical type rotating shaft;

Step 2.2, ball bar direction illustrate composition error direction of measurement, according to each ball bar direction, position, select suitable rotating shaft geometric error to affect formula to machine tool accuracy, ball bar coordinate is substituted into, ball bar reading and rotating shaft geometric error relation can be obtained;

Step 2.3, six position ball bar numbers and rotating shaft geometric error relation are converted to matrix form, thus obtain geometric error discernibility matrixes M:

$M=\left[\begin{array}{cccccc}-1& 0& 0& 0& -z_1& 0\\ 0& -1& 0& z_1& 0& 0\\ 0& 0& -1& 0& 0& 0\\ -1& 0& 0& 0& -z_1& y_4\\ -1& 0& 0& 0& -z_5& 0\\ 0& -1& 0& z_5& 0& 0\end{array}\right]$

M discloses the relation of rotating shaft geometric error and ball bar reading, is 6 × 6 matrixes.

Further, in conjunction with the definition of each geometric error of rotating shaft in step 3, obtain rotating shaft geometric error item identification formula and comprise step:

Step 3.1, utilize ball bar reading and error identification matrix, obtain measuring rotating shaft six synthetic geometry error identification formula, wherein synthetic geometry error term contains the error of perpendicularity and rotary shaft position deviation.

Step 3.2, character in conjunction with the error of perpendicularity and position deviation, isolate two error of perpendicularitys and two position deviations of rotating shaft from six synthetic geometry errors.The error of perpendicularity and site error are the errors irrelevant with the rotating shaft anglec of rotation, and represent angle and the position deviation relation of adjacent shaft, its error amount is a constant value.In the synthetic geometry error that identification obtains, the error of perpendicularity is by the part as angular errors, and site error is regarded as a part for linearity error.And basic geometric error item changes along with the rotating shaft anglec of rotation, and be defined as 0 at six elementary error items at rotating shaft zero position place, so can obtain the identification formula of rotating shaft 10 geometric errors from synthetic geometry error.

Further, select during suitable coordinate, to ensure that geometric error discernibility matrixes M is full rank to six measuring positions in step 4.

Further, when running lathe code after installing ball bar in step 4, lathe code should ensure that ball bar is followed and measure rotating shaft synchronous rotary one week or one section of circular arc.Namely ball bar is measuring the invariant position on rotating shaft coordinate system, and ball bar sensor ball is circular arc or whole circle relative to the track of astrosphere, can utilize lathe RTCP functional realiey.

Compared with prior art, the inventive method is suitable for dissimilar rotating shaft, has nothing to do, there is not original reason error with machine tool error model.

The present invention is that the rotary axis of machine tool geometric error six measured based on ball bar encloses discrimination method, and concrete beneficial effect is:

In the present invention, the coordinate of ball bar six measuring positions forms geometric error discernibility matrixes, all ensures that ball bar is followed rotating shaft synchronous rotary and obtained a ball bar reading in when ball bar runs lathe code at six measuring positions place simultaneously.The method is suitable for different rotary axis of machine tools, only need find six positions suitable in rotating shaft coordinate system, and the method systematicness is good simultaneously, identification can obtain all 10 geometric error items of rotating shaft.

Accompanying drawing explanation

Fig. 1 is the structural representation of certain five-axle number control machine tool;

Fig. 2 is lower six the measuring position schematic diagrames of C axis coordinate system of the present invention;

Fig. 3 a is 3 corner geometric errors of lathe C axle of the present invention;

Fig. 3 b is 3 linear geometry errors of lathe C axle of the present invention;

Fig. 4 is ball bar reading comparison diagram before and after position 1 place C axis error compensates;

Fig. 5 the present invention is based on the rotary axis of machine tool geometric error six that ball bar measures to enclose the flow chart of discrimination method.

Detailed description of the invention

Below in conjunction with the drawings and specific embodiments, the present invention will be further described.

Attachedly Figure 5 shows that the rotary axis of machine tool geometric error six measured based on ball bar of the present invention encloses discrimination method flow chart, attachedly Figure 1 shows that certain five-axle number control machine tool structural representation, for this lathe, illustrate the inventive method.

According to rotary axis of machine tool particular type and position in step 1, determine six measuring positions of ball bar under rotating shaft coordinate system, comprise step:

Step 1.1, determine that this rotary axis of machine tool type is A axle and C axle, the present embodiment carries out for this lathe C axle.According to machine tool structure and C shaft position, setting C axis coordinate system initial point is at C axle pivot and A axle crossing point of axes, and rotating shaft coordinate system z-axis is C axle rotating shaft center, and rotating shaft coordinate system x-axis is A axle axis;

Step 1.2, determine ball bar six measuring positions under C axis coordinate system, comprise astrosphere position on ball bar direction and ball bar, specific as follows:

Ball bar direction, position 1 place is parallel with rotating shaft coordinate system x-axis direction, and astrosphere coordinate is [0,0, z ₁]; Ball bar direction, position 2 place is parallel with rotating shaft coordinate system y-axis direction, and astrosphere coordinate is [0,0, z ₁]; Position 3 place ball bar overlaps with rotating shaft coordinate system z-axis, and astrosphere coordinate is [0,0, z ₁]; Ball bar direction, position 4 place is parallel with rotating shaft coordinate system x-axis direction, and astrosphere coordinate is [0, y ₄, z ₁]; Ball bar direction, position 5 place is parallel with rotating shaft coordinate system x-axis direction, and astrosphere coordinate is [0,0, z ₅]; Ball bar direction, position 6 place is parallel with rotating shaft coordinate system y-axis direction, and astrosphere coordinate is [0,0, z ₅].Accompanying drawing 2 is C axis coordinate system lower six measuring position schematic diagrames, wherein z ₁, y ₄, z ₅for the coordinate value of respective coordinates point.

Step 2, according to rotating shaft geometric error, machine tool accuracy to be affected, and in conjunction with ball bar direction, six measuring positions place, obtain each measuring position place ball bar reading and rotating shaft geometric error relation, and then obtain rotating shaft geometric error discernibility matrixes M, comprise step:

Step 2.1, according to lathe geometric error model, obtaining C axle geometric error affects expression formula to machine tool accuracy, and specific implementation process is as follows:

Under lathe geometric error model should be transformed into and measure rotating shaft coordinate system, for this lathe, C axle is connected with workbench, then geometric error model illustrates the composition error under C axis coordinate system, in order to identification is convenient, just bring basic for C axle geometric error item into lathe geometric error model, ignore the impact of linear axes error.When C Shaft angle is 0, the coordinate of cutter under C axis coordinate system is [x _o, y _o, z _o], so after C axle rotates to an angle γ, constant in order to ensure the coordinate of cutter under C axis coordinate system, so

$T_t^w{}_d\·{\left[\mathrm{0,0,0,1}\right]}^T={[x_o,y_o,z_o,1]}^T$

Wherein: represent the desirable homogeneous transform matrix of cutter under stage coordinates system (C axis coordinate system);

Then can obtain three corresponding amount of feeding of translation shaft is:

$\left[\begin{array}{c}x\\ y\\ z\\ 1\end{array}\right]=\left[\begin{array}{cccc}\cos \mathrm{\γ}& -\sin \mathrm{\γ}& 0& 0\\ \sin \mathrm{\γ}& \cos \mathrm{\γ}& 0& 0\\ 0& 0& 1& 0\\ 0& 0& 0& 1\end{array}\right]\·\left[\begin{array}{c}{x}_o\\ y_o\\ z_o\\ 1\end{array}\right]=\left[\begin{array}{c}{x}_o\cos \mathrm{\γ}-y_o\sin \mathrm{\γ}\\ x_o\sin \mathrm{\γ}+y_o\cos \mathrm{\γ}\\ z_o\\ 1\end{array}\right]$

After obtaining C axle motion γ angle, bring the amount of feeding of each translation shaft into lathe geometric error model, as the lathe geometric error model based on many-body theory, see Wang J, Guo J (2012) Research on volumetric error compensation for NC machine tool based on laser tracker measurement.Science China Technological Sciences55 (11): 3000-3009.The composition error obtaining all directions is:

$\left[\begin{array}{c}{\mathrm{\Δ}}_x\\ {\mathrm{\Δ}}_y\\ {\mathrm{\Δ}}_z\\ 0\end{array}\right]={(T_C^A{}_d\·T_C^A{}_e)}^{-1}\·\left[\begin{array}{c}{x}_o\cos \mathrm{\γ}-y_o\sin \mathrm{\γ}\\ x_o\sin \mathrm{\γ}+y_o\cos \mathrm{\γ}\\ z_o\\ 1\end{array}\right]-\left[\begin{array}{c}{x}_o\\ y_o\\ z_o\\ 1\end{array}\right]$

Obtain C axle geometric error through arrangement and expression formula affected on machine tool accuracy:

Δ _x＝-δ _xc+y _oε _zc-z _oε _yc

Δ _y＝-δ _yc+z _oε _xc-x _oε _zc

Δ _z＝-δ _zc+x _oε _yc-y _oε _xc (1)

Itself and lathe geometric error model have nothing to do, and directly can obtain according to the definition of each error and coordinate system transformation.Wherein δ _icrepresent the linearity error in C axle i direction; ε _icrepresent the angular errors in C axle i direction; Δ _irepresent the composition error in i direction; Wherein, i is respectively x, y, z; X, y, z represents x-axis (direction), y-axis (direction), z-axis (direction) respectively. represent the desirable homogeneous transform matrix of C axle relative to A axis coordinate system represent the error homogeneous matrix of C axle relative to A axis coordinate system.

Step 2.2, ball bar direction illustrate composition error direction of measurement, according to each ball bar direction, position, select suitable rotating shaft geometric error to affect formula to machine tool accuracy, ball bar coordinate is substituted into, ball bar reading and rotating shaft geometric error relation can be obtained, specific as follows:

Position Isosorbide-5-Nitrae, the direction of 5 place's ball bars is parallel with tested rotating shaft coordinate system x-axis direction, and what namely ball bar was measured is the General Linear error in rotating shaft coordinate system x direction; Position 2 is parallel with tested rotating shaft coordinate system y-axis direction with the direction of 6 place's ball bars, measures the General Linear error in rotating shaft coordinate system y direction; Position 3 place ball bar is positioned at surveys rotating shaft coordinate system z-axis, measures the General Linear error in rotating shaft coordinate system z direction.So select suitable expression formula in formula (1), ball bar coordinate is substituted into can the composition error of each position be:

Δ _x1＝-δ _xc-z ₁ε _yc

Δ _y2＝-δ _yc+z ₁ε _xc

Δ _z3＝-δ _zc

Δ _x4＝-δ _xc+y ₄ε _zc-z ₁ε _yc

Δ _x5＝-δ _xc-z ₅ε _yc

Δ _y6＝-δ _yc+z ₅ε _xc (2)

Wherein, Δ _ikrepresent i direction, k position composition error, i.e. k position ball bar reading, wherein i=x, y, z; K=1,2,3,4,5,6;

Step 2.3, six position ball bar numbers and rotating shaft geometric error relation are converted to matrix form,

$\left[\begin{array}{c}{\mathrm{\Δ}}_{x1}\\ {\mathrm{\Δ}}_{y2}\\ {\mathrm{\Δ}}_{z3}\\ {\mathrm{\Δ}}_{x4}\\ {\mathrm{\Δ}}_{x5}\\ {\mathrm{\Δ}}_{y6}\end{array}\right]=\left[\begin{array}{cccccc}-1& 0& 0& 0& -z_1& 0\\ 0& -1& 0& z_1& 0& 0\\ 0& 0& -1& 0& 0& 0\\ -1& 0& 0& 0& -z_1& y_4\\ -1& 0& 0& 0& -z_5& 0\\ 0& -1& 0& z_5& 0& 0\end{array}\right]\·\left[\begin{array}{c}{\mathrm{\δ}}_{\mathrm{xc}}\\ {\mathrm{\δ}}_{\mathrm{yc}}\\ {\mathrm{\δ}}_{\mathrm{zc}}\\ {\mathrm{\ϵ}}_{\mathrm{xc}}\\ {\mathrm{\ϵ}}_{\mathrm{yc}}\\ {\mathrm{\ϵ}}_{\mathrm{zc}}\end{array}\right]=M\·\left[\begin{array}{c}{\mathrm{\δ}}_{\mathrm{xc}}\\ {\mathrm{\δ}}_{\mathrm{yc}}\\ {\mathrm{\δ}}_{\mathrm{zc}}\\ {\mathrm{\ϵ}}_{\mathrm{xc}}\\ {\mathrm{\ϵ}}_{\mathrm{yc}}\\ {\mathrm{\ϵ}}_{\mathrm{zc}}\end{array}\right]$

Thus obtain rotating shaft geometric error discernibility matrixes M.

$M=\left[\begin{array}{cccccc}-1& 0& 0& 0& -z_1& 0\\ 0& -1& 0& z_1& 0& 0\\ 0& 0& -1& 0& 0& 0\\ -1& 0& 0& 0& -z_1& y_4\\ -1& 0& 0& 0& -z_5& 0\\ 0& -1& 0& z_5& 0& 0\end{array}\right]---\left(3\right)$

Step 3, utilize rotating shaft geometric error discernibility matrixes M and in conjunction with each geometric error of rotating shaft definition, obtain rotating shaft geometric error item identification formula, comprise step:

Step 3.1, utilize ball bar reading and rotating shaft geometric error discernibility matrixes M, obtain measuring rotating shaft six synthetic geometry error identification formula and be:

$\left[\begin{array}{c}{{\mathrm{\δ}}_{\mathrm{xc}}}^{\′}\\ {{\mathrm{\δ}}_{\mathrm{yc}}}^{\′}\\ {{\mathrm{\δ}}_{\mathrm{zc}}}^{\′}\\ {{\mathrm{\ϵ}}_{\mathrm{xc}}}^{\′}\\ {{\mathrm{\ϵ}}_{\mathrm{yc}}}^{\′}\\ {{\mathrm{\ϵ}}_{\mathrm{zc}}}^{\′}\end{array}\right]=M^{-1}\·\left[\begin{array}{c}{\mathrm{\Δ}}_{x1}\\ {\mathrm{\Δ}}_{y2}\\ {\mathrm{\Δ}}_{z3}\\ {\mathrm{\Δ}}_{x4}\\ {\mathrm{\Δ}}_{x5}\\ {\mathrm{\Δ}}_{y6}\end{array}\right]---\left(4\right)$

Synthetic geometry error term contains the error of perpendicularity and the rotary shaft position deviation of rotating shaft.Wherein δ _ic' represent the General Linear error in C axle i direction, ε _ic' represent the comprehensive angular errors in C axle i direction.

Step 3.2, character in conjunction with the error of perpendicularity and position deviation, isolate two error of perpendicularitys and two position deviations of rotating shaft from six synthetic geometry errors.The error of perpendicularity and site error are the errors irrelevant with the rotating shaft anglec of rotation, and represent angle and the position deviation relation of adjacent shaft, its error amount is a constant value.In the synthetic geometry error that identification obtains, the error of perpendicularity is by the part as angular errors, and site error is regarded as a part for linearity error.And basic geometric error item changes along with the rotating shaft anglec of rotation, and be defined as 0 at six elementary error items at rotating shaft zero position place, so can obtain the identification formula of 10 geometric errors of rotating shaft from synthetic geometry error, concrete geometric error identification formula is as follows:

S _cx＝ε _yc'| _γ＝0 ε _yc＝ε _yc'-S _cx

S _cy＝ε _xc'| _γ＝0 ε _xc＝ε _xc'-S _cy

o _cx＝δ _xc'| _γ＝0 δ _xc＝δ _xc'-o _cx

o _cy＝δ _yc'| _γ＝0 δ _yc＝δ _yc'-o _cy (5)

ε _zc＝ε _zc'-ε _zc'| _γ＝0 δ _zc＝δ _zc'-δ _zc'| _γ＝0

Wherein S _cxrepresent the vertical error between C axle and X-axis, S _cyrepresent the vertical error between C axle and Y-axis, o _cxrepresent the position deviation of C axle in x direction, o _cyrepresent C axle position deviation in y-direction.

Step 4, select suitable coordinate to install ball bar to six measuring positions, because machine tool structure restriction, position 1,2 in six circle methods, the z coordinate of 3 can not be 0, makes z according to installation actual conditions ₁=68mm, the y of position 4 ₄=40mm, the z of position 5 and 6 ₅=90mm, so just can obtain discernibility matrixes M, runs corresponding lathe code, utilizes lathe RTCP function, ensures that ball bar follows C axle synchronous rotary one week, obtain C axle in each position corresponding ball bar reading;

Step 5, bring ball bar reading and measuring position coordinate into rotating shaft geometric error identification formula (4) and (5), obtain 10 geometric errors that C axle is all, accompanying drawing 3a, accompanying drawing 3b are 6 basic geometric error items of C axle.Wherein, Fig. 3 a is 3 corner geometric errors of this Digit Control Machine Tool C axle; Fig. 3 b is 3 linear geometry errors of this Digit Control Machine Tool C axle.The rotating shaft error that can obtain identification compensates, then each position ball bar reading after metrophia compensation, and compares with uncompensated survey measurements.The rotating shaft error amount that identification obtains, can compensate by corresponding translation shaft, and accompanying drawing 4 is position 1 place comparative effectiveness figure.Can verify that this invention rotating shaft geometric error six encloses discrimination method identification precision high.This invention equally can 10 geometric error items of another rotating shaft of this lathe of identification A axle.

The present invention finally obtains 10 geometric error items of rotary axis of machine tool.Accompanying drawing is a preferred embodiment; the above embodiments are just in order to describe the present invention, not in order to limit the present invention, within the spirit and principles in the present invention all; any amendment of doing, equivalent replacement, improvement etc., within the protection domain that all should be included in this aspect.

Claims (8)

1. the rotary axis of machine tool geometric error six measured based on ball bar encloses a discrimination method, it is characterized in that, comprises the steps:

Step 1, according to rotary axis of machine tool type and position, determine six measuring positions of ball bar under rotating shaft coordinate system;

Step 2, according to rotating shaft geometric error, machine tool accuracy to be affected, and in conjunction with ball bar direction, six measuring positions place, obtain each measuring position place ball bar reading and rotating shaft geometric error relation, and then obtain rotating shaft geometric error discernibility matrixes M;

Step 3, utilize rotating shaft geometric error discernibility matrixes M and in conjunction with each geometric error of rotating shaft definition, obtain rotating shaft geometric error item identification formula;

Step 4, select suitable coordinate to install ball bar to six measuring positions, run corresponding lathe code, obtain rotating shaft in each position corresponding ball bar reading;

Step 5, bring ball bar reading and measuring position coordinate into rotating shaft geometric error identification formula, obtain 10 geometric errors that each rotating shaft is all.

2. the rotary axis of machine tool geometric error six measured based on ball bar according to claim 1 encloses discrimination method, it is characterized in that, in described step 1, according to rotary axis of machine tool particular type and position, determine six measuring positions of ball bar under rotating shaft coordinate system, comprise step:

Step 1.1, determine rotary axis of machine tool type, set the rotating shaft coordinate system of rotating shaft to be measured according to machine tool structure and rotary shaft position;

Step 1.2, determine ball bar six measuring positions under corresponding rotation axis coordinate system, comprise astrosphere position on ball bar direction and ball bar, specific as follows:

Ball bar direction, position 1 place is parallel with rotating shaft coordinate system x-axis direction, and astrosphere coordinate is [0,0, z ₁]; Ball bar direction, position 2 place is parallel with rotating shaft coordinate system y-axis direction, and astrosphere coordinate is [0,0, z ₁]; Position 3 place ball bar overlaps with rotating shaft coordinate system z-axis, and astrosphere coordinate is [0,0, z ₁]; Ball bar direction, position 4 place is parallel with rotating shaft coordinate system x-axis direction, and astrosphere coordinate is [0, y ₄, z ₁]; Ball bar direction, position 5 place is parallel with rotating shaft coordinate system x-axis direction, and astrosphere coordinate is [0,0, z ₅]; Ball bar direction, position 6 place is parallel with rotating shaft coordinate system y-axis direction, and astrosphere coordinate is [0,0, z ₅], wherein z ₁, y ₄, z ₅for the coordinate value of respective coordinates point.

3. the rotary axis of machine tool geometric error six measured based on ball bar according to claim 1 encloses discrimination method, it is characterized in that, in described step 2, obtain rotating shaft geometric error discernibility matrixes M in conjunction with ball bar direction, six measuring positions place and coordinate, comprise step:

Step 2.1, according to lathe geometric error model, obtaining rotating shaft geometric error affects expression formula to machine tool accuracy, wherein on dissimilar lathe the rotating shaft geometric error of identical type to affect expression formula to machine tool accuracy consistent;

Step 2.2, ball bar direction illustrate composition error direction of measurement, according to each ball bar direction, position, select the rotating shaft geometric error consistent with its direction to affect formula to machine tool accuracy, ball bar coordinate is substituted into, ball bar reading and rotating shaft geometric error relation can be obtained;

Step 2.3, six position ball bar readings and rotating shaft geometric error relation are converted to matrix form, thus obtain geometric error discernibility matrixes M:

$M=\left[\begin{array}{cccccc}-1& 0& 0& 0& -z_1& 0\\ 0& -1& 0& z_1& 0& 0\\ 0& 0& -1& 0& 0& 0\\ -1& 0& 0& 0& -z_1& y_4\\ -1& 0& 0& 0& -z_5& 0\\ 0& -1& 0& z_5& 0& 0\end{array}\right]$

Wherein z ₁, y ₄, z ₅for the coordinate value of respective coordinates point.

4. the rotary axis of machine tool geometric error six measured based on ball bar according to claim 3 encloses discrimination method, it is characterized in that, in step 2.1, solve rotating shaft geometric error when expression formula is affected on machine tool accuracy, only bring basic for rotating shaft geometric error item into lathe geometric error model, ignore the impact of linear axes error, under lathe geometric error model being transformed into rotating shaft coordinate system to be measured simultaneously.

5. the rotary axis of machine tool geometric error six measured based on ball bar according to claim 1 encloses discrimination method, it is characterized in that, in described step 3, in conjunction with the definition of each geometric error of rotating shaft, obtains rotating shaft geometric error item identification formula, comprises step:

Step 3.1, utilize ball bar reading and rotating shaft geometric error discernibility matrixes M, obtain the identification formula of six synthetic geometry errors of rotating shaft to be measured, wherein synthetic geometry error packet contains the error of perpendicularity and rotary shaft position deviation;

Step 3.2, character in conjunction with the error of perpendicularity and position deviation, isolate two error of perpendicularitys and two position deviations of rotating shaft from six synthetic geometry errors; Wherein the error of perpendicularity and site error are the errors irrelevant with the rotating shaft anglec of rotation, and represent angle and the position deviation relation of adjacent shaft, its error amount is a constant value; In the synthetic geometry error that identification obtains, the error of perpendicularity is by the part as angular errors, and site error is regarded as a part for linearity error; And basic geometric error item changes along with the rotating shaft anglec of rotation, be defined as 0 in six synthetic geometry errors at rotating shaft zero position place, from six synthetic geometry errors, finally obtain the identification formula of rotating shaft 10 geometric errors.

6. the rotary axis of machine tool geometric error six measured based on ball bar according to claim 1 encloses discrimination method, it is characterized in that, in described step 4, select to need during suitable coordinate to ensure that rotating shaft geometric error discernibility matrixes M is full rank to six measuring positions.

7. the rotary axis of machine tool geometric error six measured based on ball bar according to claim 1 encloses discrimination method, it is characterized in that, in described step 4, when running lathe code after ball bar is installed, lathe code needs to ensure that ball bar follows rotating shaft synchronous rotary to be measured one week or one section of circular arc, namely ball bar is measuring the invariant position on rotating shaft coordinate system, and the sensor ball of ball bar is circular arc or whole circle relative to the track of astrosphere.

8. the rotary axis of machine tool geometric error six measured based on ball bar according to claim 3 encloses discrimination method, it is characterized in that, in described step 2.1, rotating shaft geometric error affects expression formula to machine tool accuracy and directly utilizes the definition of each geometric error item to obtain.