CN104308657B - A kind of rotary axis of machine tool geometric error six measured based on ball bar encloses discrimination method - Google Patents

Abstract

The present invention discloses a kind of rotary axis of machine tool geometric error six measured based on ball bar and encloses discrimination method, comprises the following steps: according to rotary axis of machine tool type and position, it is determined that six measuring positions of ball bar; According to turning axle geometric error, machine tool accuracy is affected, and in conjunction with ball bar direction, six measuring positions place, obtain each position ball bar reading and turning axle geometric error relation, obtain turning axle geometric error discernibility matrixes M; In conjunction with the definition of each geometric error of turning axle, obtain turning axle geometric error item identification formula; Select suitable coordinate to install ball bar six measuring positions, run corresponding lathe code, obtain turning axle in each position corresponding ball bar reading; Ball bar reading and measuring position coordinate are brought into turning axle geometric error identification formula, obtains 10 geometric errors that each turning axle is all. This invention is suitable for dissimilar turning axle, and without principle error, system entries is good, and it is convenient to measure, identification precision height.

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 numerically-controlled machine 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 production is increasing. On workpiece quality impact greatly, it is the major criterion weighing a lathe to the working accuracy of lathe. Geometric error repeatability is good, stablizing constant, so being easy to realize the compensation of geometric error, improving the working accuracy of lathe in for a long time.

Geometric Error for Computerized Numerical Control Milling Machine model is the basis of geometric error compensation, these models can be used for predict and compensate lathe geometric error, but prerequisite is exactly each geometric error item in model need measure identification obtain. The discrimination method of 21 geometric errors of three axle lathes is more ripe, measurement for the turning axle error of five-axle number control machine tool has also occurred a lot of method and device both at home and abroad, and 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) ZagarbashiS.H.H. and MayerJ.R.R. proposes the geometric error that based on ball bar five kinds of test phases carry out identification lathe A axle, and the method only needs the independent rotary motion of A axle. (see ZargarbashiSHH, MayerJRR (2006) Assessmentofmachinetooltrunnionaxismotionerror, usingmagneticdoubleballbar, InternationalJournalofMachineToolsandManufacture46 (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-IILee uses ball bar to propose five kinds of test paths for C axle, and represents to come that identification obtains geometric error item by C axle geometric error item parametrization. (see LeeKI, LeeDM, YangSH (2012) Parametricmodelingandestimationofgeometricerrorsforarota ryaxisusingdoubleball-bar.InternationalJournalofAdvanced ManufacturingTechnology62 (5-8): 741-750). But the method is easy for C axle, is not suitable for other type turning axles.

(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 turning axle 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 the five-axis machine tool of all types.

The discrimination method of three axis numerically controlled machine 21 geometric errors has the 9 line methods based on laser interferometer, 12 line methods, 21 line 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 principle error, is applicable to different three axis numerically controlled machines. Not as this kind of 9 line methods is measured conveniently in turning axle measuring method, the discrimination method that be suitable for different rotary axle unrelated 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 turning axle simultaneously, does not have versatility.

Summary of the invention

It is an object of the invention to propose a kind of rotary axis of machine tool geometric error six measured based on ball bar and enclose discrimination method, realize turning axle geometric error identification in conjunction with ball bar measuring characteristic. This invention is not only suitable for dissimilar turning axle, 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, it is determined that six measuring positions of ball bar;

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

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

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

Step 5 into, ball bar reading and measuring position coordinate are brought turning axle geometric error identification formula, obtain 10 geometric errors that each turning axle is all;

According to rotary axis of machine tool particular type and position in step 1, it is determined that six measuring positions of ball bar under turning axle system of coordinates, 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 turning axle system of coordinates;

Step 1.2, six measuring positions of determining ball bar under turning axle system of coordinates, comprise center ball position on ball bar direction and ball bar, specific as follows:

Ball bar direction, position 1 place is parallel with turning axle system of coordinates x-axis direction, and centrosphere coordinate is [0,0, z₁]; Ball bar direction, position 2 place is parallel with turning axle system of coordinates y-axis direction, and centrosphere coordinate is [0,0, z₁]; Position 3 place ball bar overlaps with turning axle system of coordinates z-axis, and centrosphere coordinate is [0,0, z₁]; Ball bar direction, position 4 place is parallel with turning axle system of coordinates x-axis direction, and centrosphere coordinate is [0, y₄,z₁]; Ball bar direction, position 5 place is parallel with turning axle system of coordinates x-axis direction, and centrosphere coordinate is [0,0, z₅]; Ball bar direction, position 6 place is parallel with turning axle system of coordinates y-axis direction, and centrosphere coordinate is [0,0, z₅]��

Further, step 2 obtains turning axle geometric error discernibility matrixes M in conjunction with ball bar direction, six measuring positions and coordinate and comprises step:

Step 2.1, according to lathe geometric error model, obtaining turning axle geometric error affects expression formula to machine tool accuracy, in order to identification is convenient, just brings basic for turning axle 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 turning axle system of coordinates to improve identification precision; Also can directly utilize the definition of turning axle geometric error item to obtain turning axle geometric error in addition and machine tool accuracy is affected expression formula; On dissimilar lathe, that machine tool accuracy is affected expression formula is consistent for the geometric error of identical type turning axle;

Step 2.2, ball bar direction illustrate overall error direction of measurement, according to each ball bar direction, position, select suitable turning axle geometric error that machine tool accuracy is affected formula, ball bar coordinate is substituted into, ball bar reading and turning axle geometric error relation can be obtained;

Step 2.3, six position ball bar numbers and turning axle 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 turning axle geometric error and the relation of ball bar reading, is 6 �� 6 matrixes.

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

Step 3.1, utilizing ball bar reading and error identification matrix, obtain measuring the comprehensive geometric error identification formula of six, turning axle, wherein comprehensive geometric error item contains verticality error and rotary shaft position deviation.

Step 3.2, in conjunction with the character of verticality error and position deviation, from six comprehensive geometric errors, isolate two verticality errors and two position deviations of turning axle. Verticality error and positionerror are the errors unrelated with turning axle angle of rotation, represent angle and the position offset relation of adjacent shaft, and its error value is a constant value. In the comprehensive geometric error that identification obtains, verticality error is by the part as angular errors, and positionerror is regarded as a part for linearity error. And basic geometric error item changes along with turning axle angle of rotation, and six intrinsic error items at turning axle zero position place are defined as 0, so can obtain the identification formula of turning axle 10 geometric errors from comprehensive geometric error.

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

Further, when running lathe code after installing ball bar in step 4, lathe code should ensure that ball bar is followed and measure turning axle synchronous rotary one week or one section of circular arc. Namely ball bar is constant in the position measured on turning axle system of coordinates, and ball bar sensor ball is circular arc or whole circle relative to the track of centrosphere, can utilize lathe RTCP functional realiey.

Compared with prior art, the inventive method is suitable for dissimilar turning axle, unrelated with machine tool error model, there is not original reason error.

The present invention is that the rotary axis of machine tool geometric error six measured based on ball bar encloses discrimination method, and concrete useful 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 turning axle 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 to find six positions suitable in turning axle system of coordinates, and the method systematicness is good simultaneously, it is possible to identification obtains all 10 geometric error items of turning axle.

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 diagram 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 that before and after position 1 place C axis error compensates, ball bar read-around ratio is relatively schemed;

Fig. 5 is that the present invention encloses the schema of discrimination method based on the rotary axis of machine tool geometric error six that ball bar is measured.

Embodiment

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

The rotary axis of machine tool geometric error six based on ball bar measurement that accompanying drawing 5 show the present invention encloses discrimination method schema, and accompanying drawing 1 show certain five-axle number control machine tool structural representation, for this lathe, illustrates the inventive method.

According to rotary axis of machine tool particular type and position in step 1, it is determined that six measuring positions of ball bar under turning axle system of coordinates, comprise step:

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

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

Ball bar direction, position 1 place is parallel with turning axle system of coordinates x-axis direction, and centrosphere coordinate is [0,0, z₁]; Ball bar direction, position 2 place is parallel with turning axle system of coordinates y-axis direction, and centrosphere coordinate is [0,0, z₁]; Position 3 place ball bar overlaps with turning axle system of coordinates z-axis, and centrosphere coordinate is [0,0, z₁]; Ball bar direction, position 4 place is parallel with turning axle system of coordinates x-axis direction, and centrosphere coordinate is [0, y₄,z₁]; Ball bar direction, position 5 place is parallel with turning axle system of coordinates x-axis direction, and centrosphere coordinate is [0,0, z₅]; Ball bar direction, position 6 place is parallel with turning axle system of coordinates y-axis direction, and centrosphere coordinate is [0,0, z₅]. Accompanying drawing 2 is C axis coordinate system lower six measuring position schematic diagram, wherein z₁��y₄��z₅For the coordinate figure of respective coordinates point.

Step 2, according to turning axle geometric error, machine tool accuracy is affected, and in conjunction with ball bar direction, six measuring positions place, obtain each measuring position place ball bar reading and turning axle geometric error relation, and then obtain turning axle 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:

Lathe geometric error model should be transformed under measuring turning axle system of coordinates, for this lathe, C axle is connected with worktable, then geometric error model illustrates the overall 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 axle corner 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 ��, 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 feed 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 �� angle, bring the amount of feed of each translation shaft into lathe geometric error model, such as the lathe geometric error model based on many bodies theory, see WangJ, GuoJ (2012) ResearchonvolumetricerrorcompensationforNCmachinetoolbas edonlasertrackermeasurement.ScienceChinaTechnologicalSci ences55 (11): 3000-3009. The overall 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 machine tool accuracy affected expression formula:

��_x=-��_xc+y_o��_zc-z_o��_yc

��_y=-��_yc+z_o��_xc-x_o��_zc

��_z=-��_zc+x_o��_yc-y_o��_xc(1)

Itself is unrelated with lathe geometric error model, it is possible to directly obtain according to the definition of each error and coordinate system transformation. Wherein ��_icRepresent the linearity error in C axle i direction; ��_icRepresent the angular errors in C axle i direction; ��_iRepresent the overall 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 systemRepresent the error homogeneous matrix of C axle relative to A axis coordinate system.

Step 2.2, ball bar direction illustrate overall error direction of measurement, according to each ball bar direction, position, select suitable turning axle geometric error that machine tool accuracy is affected formula, ball bar coordinate is substituted into, ball bar reading and turning axle geometric error relation can be obtained, specific as follows:

The direction of position 1,4,5 place ball bar is parallel with tested turning axle system of coordinates x-axis direction, and namely what ball bar was measured is the General Linear error in turning axle system of coordinates x direction; Position 2 is parallel with tested turning axle system of coordinates y-axis direction with the direction of 6 place's ball bars, measures the General Linear error in turning axle system of coordinates y direction; Position 3 place ball bar is positioned at surveys turning axle system of coordinates z-axis, measures the General Linear error in turning axle system of coordinates z direction. Formula (1) is so selected suitable expression formula, ball bar coordinate is substituted into can the overall error of each position be:

��_x1=-��_xc-z₁��_yc

��_y2=-��_yc+z₁��_xc

��_z3=-��_zc

��_x4=-��_xc+y₄��_zc-z₁��_yc

��_x5=-��_xc-z₅��_yc

��_y6=-��_yc+z₅��_xc(2)

Wherein, ��_ikRepresent i direction, k location place overall error, i.e. k location place ball bar reading, wherein i=x, y, z; K=1,2,3,4,5,6;

Step 2.3, six position ball bar numbers and turning axle 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 turning axle 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 turning axle geometric error discernibility matrixes M and in conjunction with each geometric error of turning axle definition, obtain turning axle geometric error item identification formula, comprise step:

Step 3.1, utilize ball bar reading and turning axle geometric error discernibility matrixes M, obtain measuring the comprehensive geometric error identification formula of six, turning axle and be:

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

Comprehensive geometric error item contains verticality error and the rotary shaft position deviation of turning axle. Wherein ��_ic' represent C axle i direction General Linear error, ��_ic' represent C axle i direction comprehensive angular errors.

Step 3.2, in conjunction with the character of verticality error and position deviation, from six comprehensive geometric errors, isolate two verticality errors and two position deviations of turning axle. Verticality error and positionerror are the errors unrelated with turning axle angle of rotation, represent angle and the position offset relation of adjacent shaft, and its error value is a constant value. In the comprehensive geometric error that identification obtains, verticality error is by the part as angular errors, and positionerror is regarded as a part for linearity error. And basic geometric error item changes along with turning axle angle of rotation, and six intrinsic error items at turning axle zero position place are defined as 0, so can obtaining the identification formula of 10 geometric errors of turning axle from comprehensive geometric error, concrete geometric error identification formula is as follows:

S_cx=��_yc'|_��=0��_yc=��_yc'-S_cx

S_cy=��_xc'|_��=0��_xc=��_xc'-S_cy

o_cx=��_xc'|_��=0��_xc=��_xc'-o_cx

o_cy=��_yc'|_��=0��_yc=��_yc'-o_cy(5)

��_zc=��_zc'-��_zc'|_��=0��_zc=��_zc'-��_zc'|_��=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, selecting suitable coordinate to install ball bar six measuring positions, because machine tool structure restriction, in six circle methods, the z coordinate of position 1,2,3 can not be 0, makes z according to installation practical situation₁=68mm, the y of position 4₄=40mm, the z of position 5 and 6₅=90mm, so just can obtain discernibility matrixes M, run 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, ball bar reading and measuring position coordinate being brought turning axle geometric error identification formula (4) and (5) into, 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 numerically-controlled machine C axle; Fig. 3 b is 3 linear geometry errors of this numerically-controlled machine C axle. The turning axle error that can identification be obtained compensates, and then measures each position ball bar reading after compensating, and compares with uncompensated survey measurements. The turning axle error value 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 turning axle geometric error six encloses discrimination method identification precision height. This invention equally can 10 geometric error items of identification this lathe another turning axle 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 being done, equivalent replacement, improvement etc., all should be included within the protection domain of present aspect.

Claims (8)

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

Step 1, according to rotary axis of machine tool type and position, it is determined that six measuring positions of ball bar under turning axle system of coordinates;

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

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

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

Step 5 into, ball bar reading and measuring position coordinate are brought turning axle geometric error identification formula, obtain 10 geometric errors that each turning axle 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 turning axle system of coordinates, comprise step:

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

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

Ball bar direction, position 1 place is parallel with turning axle system of coordinates x-axis direction, and centrosphere coordinate is [0,0, z₁]; Ball bar direction, position 2 place is parallel with turning axle system of coordinates y-axis direction, and centrosphere coordinate is [0,0, z₁]; Position 3 place ball bar overlaps with turning axle system of coordinates z-axis, and centrosphere coordinate is [0,0, z₁]; Ball bar direction, position 4 place is parallel with turning axle system of coordinates x-axis direction, and centrosphere coordinate is [0, y₄,z₁]; Ball bar direction, position 5 place is parallel with turning axle system of coordinates x-axis direction, and centrosphere coordinate is [0,0, z₅]; Ball bar direction, position 6 place is parallel with turning axle system of coordinates y-axis direction, and centrosphere coordinate is [0,0, z₅], wherein z₁��y₄��z₅For the coordinate figure 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 turning axle 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 turning axle geometric error affects expression formula to machine tool accuracy, wherein on dissimilar lathe the turning axle geometric error of identical type that machine tool accuracy is affected expression formula is consistent;

Step 2.2, ball bar direction illustrate overall error direction of measurement, according to each ball bar direction, position, select the turning axle geometric error consistent with its direction that machine tool accuracy is affected formula, ball bar coordinate is substituted into, ball bar reading and turning axle geometric error relation can be obtained;

Step 2.3, six measuring positions place ball bar reading and turning axle 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 z₁��y₄��z₅For the coordinate figure 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 turning axle geometric error when machine tool accuracy is affected expression formula, only bring basic for turning axle geometric error item into lathe geometric error model, ignore the impact of linear axes error, under lathe geometric error model being transformed into turning axle system of coordinates 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 characterised in that, in described step 3, in conjunction with the definition of each geometric error of turning axle, obtain turning axle geometric error identification formula, comprise step:

Step 3.1, utilizing ball bar reading and turning axle geometric error discernibility matrixes M, obtain the identification formula of six comprehensive geometric errors of turning axle to be measured, wherein comprehensive geometric error contains verticality error and rotary shaft position deviation;

Step 3.2, in conjunction with the character of verticality error and rotary shaft position deviation, from six comprehensive geometric errors, isolate two verticality errors and two position deviations of turning axle; Wherein verticality error and position deviation are the errors unrelated with turning axle angle of rotation, represent angle and the position offset relation of adjacent shaft, and its error value is a constant value; In the comprehensive geometric error that identification obtains, verticality error is regarded as a part for linearity error by the part as angular errors, position deviation; And basic geometric error item changes along with turning axle angle of rotation, six comprehensive geometric errors at turning axle zero position place are defined as 0, finally obtain the identification formula of turning axle 10 geometric errors from six comprehensive 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 six measuring positions to need during suitable coordinate to ensure that turning axle geometric error discernibility matrixes M is full rank.

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 turning axle synchronous rotary to be measured one week or one section of circular arc, namely ball bar is constant in the position measured on turning axle system of coordinates, and the sensor ball of ball bar is circular arc or whole circle relative to the track of centrosphere.

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