CN103878641B - The rotating shaft geometric error discrimination method that a kind of five-axle number control machine tool is general - Google Patents

Abstract

The invention discloses the rotating shaft geometric error discrimination method that a kind of five-axle number control machine tool is general, including: according to five-axle number control machine tool type, it is determined that ball bar measurement pattern；According to Geometric Error for Computerized Numerical Control Milling Machine model, utilize ball bar sensitivity vector, it is thus achieved that ball bar reading model；According to ball bar reading model and ball bar measurement pattern, the character of geometric error item and translation shaft geometric error item, obtain rotary axis of machine tool geometric error item expression formula；Select suitable installation parameter, run lathe, obtain corresponding ball bar reading；Input three translation shaft geometric error items of five-axle number control machine tool, according to rotating shaft geometric error item expression formula and ball bar reading, obtain 16 geometric errors of two rotating shafts of five-axle number control machine tool.This invention is suitable for different types of five-axle number control machine tool, it is possible to obtain whole 16 geometric errors of two rotating shafts of lathe, installs simple simultaneously, and the time of measuring is short, and identification result meets the character of geometric error item, and certainty of measurement is high.

Description

The rotating shaft geometric error discrimination method that a kind of five-axle number control machine tool is general

Technical field

The present invention relates to five-axle number control machine tool error identification field, particularly relate to the rotating shaft geometric error discrimination method that a kind of five-axle number control machine tool is general.

Background technology

Along with processing manufacturing industry is more and more higher to the requirement of precision and efficiency, five-axle number control machine tool is more and more important in manufacture field.In general, five-axle number control machine tool comprises two rotating shafts and three linear axes.The two rotating shaft can provide rotary motion to adjust cutter-orientation thus reducing clamping workpiece number of times.Rotating shaft makes five-axle number control machine tool have the advantages such as stock removal rate height, surface accuracy is high, process time is few.But rotating shaft have also been introduced a lot of error term so that machine tool error modeling and error compensation are relatively difficult.

Improving machine tool accuracy to realize five-axis machine tool geometric error compensation, the measurement of geometric error item is just particularly important.The geometric error item of five-axle number control machine tool includes 21 geometric error items of translation shaft and 16 geometric error items of two rotating shafts.Measuring method for translation shaft geometric error item is a lot, has 9 collimation methods, 12 collimation methods, 21 collimation methods and substep diagonal method etc., and survey tool has laser interferometer, laser tracker, ball bar, level indicator etc..So the 21 of translation shaft geometric error items can be measured and obtain.But the measurement for the geometric error item of rotary axis of machine tool is still left to be desired and improves.For measurement and the identification of rotating shaft error, Chinese scholars proposes a lot of discrimination method.

(1) MasaomiTsutsumi and AkinoriSaito uses ball bar to propose three-shaft linkage and four-axle linked method is measured and analyzed the geometric error item obtaining rotary axis of machine tool.null(referring to TsutsumiM,SaitoA(2003)Identificationandcompensationofsystematicdeviationsparticularto5-axismachiningcenters,InternationalJournalofMachineToolsandManufacture43 (8): 771-780 and TsutsumiM,SaitoA(2004)Identificationofangularandpositionaldeviationsinherentto5-axismachiningcenterswithatilting-rotarytablebysimultaneousfour-axiscontrolmovements,InternationalJournalofMachineToolsandManufacture44 (12 13): 1333-1342).But the geometric error item that the method obtains is all fixed value, this geometric properties with geometric error item does not correspond.Next does not account for the impact of 21 geometric error items of translation shaft so that identification precision reduces, because multi-shaft interlocked middle translation shaft is also synchronized with the movement, identification precision is had a significant impact by its error term.Last the method has to 8 errors of two rotating shafts, does not obtain whole 16 errors of two rotating shafts.

(2) ZagarbashiS.H.H. and MayerJ.R.R. utilizes ball bar to propose a kind of A axle geometric error discrimination method, and the method only needs the independently moving of A axle, it is also considered that the alignment error of ball bar.(referring to ZargarbashiSHH, MayerJRR (2006) Assessmentofmachinetooltrunnionaxismotionerror, usingmagneticdoubleballbar, InternationalJournalofMachineToolsandManufacture46 (14): 1823-1834).But the method cannot obtain the error of perpendicularity and the angle position error of A axle.

(3) LeiW.T. et al. adopts ball bar to propose a kind of special Circular test method to measure rotating shaft geometric error item.This Circular test is synchronized with the movement by translation shaft and rotating shaft and is formed.(referring to LeiWT, SungMP, LiuWL, ChuangYC (2007) Doubleballbartestfortherotaryaxesoffive-axisCNCmachineto ols, InternationalJournalofMachineToolsandManufacture47 (2): 273-285).But the method identification can only obtain kinematic error, it is impossible to identification obtains the error of perpendicularity.

(4) Kwang-IILee et al. uses ball bar to propose a series of method and obtain kinematic geometry error term and the geometry of position error term of C axle to measure identification.(referring to LeeKI, LeeDM, YangSH (2012) Parametricmodelingandestimationofgeometricerrorsforarota ryaxisusingdoubleball-bar.InternationalJournalofAdvanced ManufacturingTechnology62 (5-8): 741-750；LeeKI, YangSH (2013) Robustmeasurementmethodanduncertaintyanalysisforposition-independentgeometricerrorsofarotaryaxisusingadoubleball-bar.InternationalJournalofPrecisionEngineeringandManufac turing14 (2): 231-239).But these methods are easy for C axle, but relatively difficult for A axle and B axle, because the method is harsher to the installation of ball bar.Additionally the method does not account for the impact of translation shaft geometric error item, and this affects identification precision.

(5) He Gaiyun et al. proposes the Five-axis NC Machining Center accuracy checking method of a kind of pair of turntable structure, and the method, by designing lathe five-axle linkage curve movement, carrys out identification rotating shaft error in conjunction with ball bar and error model.(referring to 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 of patent, 2013 years, publication number was CN102944197A).But the method does not account for the impact of translation shaft error.

Summary of the invention

From now methodical defect, the invention provides a kind of general rotating shaft geometric error discrimination method being suitable for various five-axle number control machine tool, it is by means of lathe following function and ball bar, all 16 geometric errors of two rotating shafts can be measured, and ball bar installation is simple and convenient, measure the time short.

The rotating shaft geometric error discrimination method that a kind of five-axle number control machine tool is general, comprises the steps:

Step 1, according to five-axle number control machine tool type, utilize the following function of five-axle number control machine tool, it is determined that ball bar measure three Installation Modes, i.e. ball bar measurement patterns；

Step 2, according to Geometric Error for Computerized Numerical Control Milling Machine model, utilize ball bar sensitivity vector, it is thus achieved that the relation between ball bar reading and rotating shaft geometric error, i.e. ball bar reading model；

Step 3, according to ball bar reading model and ball bar measurement pattern, in conjunction with the character of rotating shaft geometric error item, it is considered to translation shaft geometric error item, obtain rotary axis of machine tool geometric error item expression formula；

Step 4, according to rotary axis of machine tool geometric error item expression formula and corresponding ball bar measurement pattern, select suitable installation parameter, run lathe according to lathe following function, obtain corresponding ball bar reading；

Step 5, input three translation shaft geometric error items of five-axle number control machine tool, according to rotary axis of machine tool geometric error item expression formula and ball bar reading, identification obtains 16 geometric errors of two rotating shafts of five-axle number control machine tool；

In step 1, five-axle number control machine tool type need to be determined according to rotary axis of machine tool type and position, then determines the concrete installation form of three ball bar measurement patterns according to machine tool type, including step:

Step 1.1, determining two rotating shaft kinds of five-axle number control machine tool: A axle, B axle or C axle, during for guaranteeing that ball bar is measured, ball bar is static relative to the rotating shaft measured, and utilizes the following function of lathe, it is determined that the machine spindle being synchronized with the movement when measuring rotating shaft；

Step 1.2, according to rotary axis of machine tool kind and the axle that is synchronized with the movement accordingly, determine the Installation Modes (i.e. the concrete installation form of measurement pattern) that ball bar is measured: in pattern one, workpiece ball coordinate under rotating shaft coordinate system is [0, M, L], the coordinate of cutter ball is [R, M, L], ball bar sensitive direction is rotating shaft coordinate system x positive direction；In pattern two, workpiece ball coordinate under rotating shaft coordinate system is [0,0, L], and the coordinate of cutter ball is [0, R, L], and ball bar sensitive direction is rotating shaft coordinate system y positive direction；In pattern three, workpiece ball coordinate under rotating shaft coordinate system is [0,0, L], and the coordinate of cutter ball is [0,0, L+R], and ball bar sensitive direction is rotating shaft coordinate system z positive direction；Wherein R is ball bar length, L be ball bar workpiece ball to rotating shaft coordinate origin z to distance, M is ball bar workpiece ball to rotating shaft coordinate origin y to distance.

Further, in order to improve error identification precision in step 2, five-axle number control machine tool geometric error model need to be converted into the error model represented under the rotating shaft coordinate system measured.Its ball bar sensitivity vector is homogeneous vectors, and in pattern one, ball bar sensitive direction is x positive direction, and its homogeneous vectors expression formula is [1,0,0,0].Rotate the machine spindle of motion when rotating shaft is measured according to lathe following function two different, then the ball bar reading model of two rotating shafts is different, and the geometric error item that it comprises is different.And under different measurement patterns, ball bar reading model is also different.

Further, according to the geometric error item comprised in ball bar reading model and each ball bar measurement pattern in step 3, to the combination of each corresponding model selection corresponding parameter, come identification obtain each pattern can the expression formula of identification, including step:

Step 3.1, according to ball bar reading model in pattern one, determine that each rotating shaft needs the geometric error item of identification, geometric properties according to geometric error item, selects three groups of parameters of pattern one, and utilizes corresponding ball bar reading to obtain the expression formula of these geometric error items.These three groups of parameters are: L=L₁, M=0, R=R；L=L₂, M=0, R=R；And L=L₁, M ≠ 0, R=R.Wherein L₁≠L₂.The expression formula of rotating shaft geometric error is consistent with its character, and namely the expression formula of kinematic error is about rotating shaft amount of feeding expression formula, geometric error item as basic in 6, rotating shaft；Site error expression formula is definite value, such as two error of perpendicularitys of rotating shaft.

Step 3.2, according to ball bar reading model in pattern two, determine that each rotating shaft needs the geometric error item of identification, geometric properties according to geometric error item, selects two groups of parameters of pattern two, and utilizes corresponding ball bar reading to obtain the expression formula of these geometric error items.These two groups of parameters are: L=L₁, R=R；And L=L₂, R=R.Wherein L₁≠L₂。

Step 3.3, according to ball bar reading model in pattern three, determine that each rotating shaft needs the geometric error item of identification, geometric properties according to geometric error item, selects one group of parameter of pattern three, and utilizes corresponding ball bar reading to obtain the expression formula of these geometric error items.This group parameter is: L=L₁, R=R.

Further, difference group parameter according to each pattern determined in step 4, combining with digital control machine tool structure selects suitable numerical value to install ball bar, runs lathe according to lathe following function, obtains each group of corresponding ball bar reading of parameter, including step:

Step 4.1, according to parameter L=L in pattern one₁, M=0, R=R installs workpiece ball, utilizes lathe following function to measure two rotating shafts respectively according to pattern one structure, and records each rotating shaft this group parameter ball bar reading correspondingWhereinSubscript represents first group of parameter；It is pattern one that subscript " 1 " represents, i represents rotating shaft type, i=a, b, c.

Step 4.2, utilize according to pattern two structure lathe following function to measure two rotating shafts respectively, and record each rotating shaft this group parameter ball bar reading corresponding

Step 4.3, utilize according to pattern three structure lathe following function to measure two rotating shafts respectively, and record each rotating shaft this group parameter ball bar reading corresponding

Step 4.4, according to parameter L=L in pattern one₁, M ≠ 0, R=R installs workpiece ball, utilizes lathe following function to measure two rotating shafts respectively according to pattern one structure, and records each rotating shaft this group parameter ball bar reading corresponding

Step 4.5, according to parameter L=L in pattern one₂, M=0, R=R installs workpiece ball, utilizes lathe following function to be separately operable two rotating shafts and its axle that is synchronized with the movement accordingly according to pattern one structure, and records each rotating shaft this group parameter ball bar reading corresponding

Step 4.6, utilize according to pattern two structure lathe following function to measure two rotating shafts and its axle that is synchronized with the movement accordingly respectively, and record each rotating shaft this group parameter ball bar reading corresponding

Further, 21 geometric error items of the lathe translation shaft of input in step 5, it is possible to obtain with laser interferometer measurement.

Compared with prior art, the inventive method considers the impact on identification precision of the translation shaft geometric error item, also considers the geometric properties of geometric error item completely so that identification precision is high, the present invention is the rotating shaft geometric error discrimination method that five-axle number control machine tool is general, concrete provides the benefit that:

In three Installation Modes that ball bar is measured, the sensitive direction of ball bar is respectively placed in x, y and z direction, guarantee that ball bar is static relative to the rotating shaft measured by lathe following function simultaneously, the installation parameter suitable to each model selection, obtains 16 geometric errors of two rotating shafts of five-axle number control machine tool in conjunction with the character identification of geometric error item.The method is suitable for different five-axle number control machine tool, measures integrity good, it is possible to measure whole 16 geometric errors obtaining two rotating shafts of lathe, installing simple, the time of measuring is short, and identification result meets the character of geometric error item simultaneously, considering the impact of translation shaft error, certainty of measurement is high.

Accompanying drawing explanation

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

Fig. 2 a is CAFYXZ Digit Control Machine Tool measurement pattern one structural representation of the present invention；

Fig. 2 b is CAFYXZ Digit Control Machine Tool measurement pattern two structural representation of the present invention；

Fig. 2 c is CAFYXZ Digit Control Machine Tool measurement pattern three structural representation of the present invention；

Fig. 3 a is 3 linear geometry errors of CAFYXZ Digit Control Machine Tool A axle of the present invention；

Fig. 3 b is 3 corner geometric errors of CAFYXZ Digit Control Machine Tool A axle of the present invention；

Fig. 4 a is 3 linear geometry errors of CAFYXZ Digit Control Machine Tool C axle of the present invention；

Fig. 4 b is 3 corner geometric errors of CAFYXZ Digit Control Machine Tool C axle of the present invention；

Fig. 5 is the geometric error item calculated ball bar reading and true ball bar reading contrast effect figure that obtain with identification；

Fig. 6 is the flow chart of the general rotating shaft geometric error discrimination method of five-axle number control machine tool of the present invention.

Detailed description of the invention

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

Accompanying drawing 6 show five-axle number control machine tool of the present invention general rotating shaft geometric error discrimination method flow chart, and accompanying drawing 1 show certain CAFYXZ type five-axle number control machine tool schematic diagram, for this lathe, illustrates rotating shaft discrimination method.

Step 1, according to five-axle number control machine tool type, utilize the following function of five-axle number control machine tool, it is determined that ball bar measure three Installation Modes:

Step 1.1, determine that two rotating shaft types of this five-axle number control machine tool are A axle and C axle.During for guaranteeing that ball bar is measured, ball bar is static relative to the rotating shaft measured, and utilizes the following function of lathe, it is determined that the axle that is synchronized with the movement when measuring A axle is A axle, Y-axis and Z axis, and the axle that is synchronized with the movement when measuring C axle is C axle, X-axis and Y-axis.

Step 1.2, according to rotary axis of machine tool kind and the axle that is synchronized with the movement accordingly, it is determined that ball bar measure Installation Modes.The type lathe A axle is all connected with workbench with C axle, then ball bar is arranged on stage coordinates and fastens.In pattern one shown in Fig. 2 a, workpiece ball coordinate under stage coordinates system is [0, M, L], and the coordinate of cutter ball is [R, M, L], and ball bar sensitive direction is rotating shaft coordinate system x positive direction；In pattern two shown in Fig. 2 b, workpiece ball coordinate under stage coordinates system is [0,0, L], and the coordinate of cutter ball is [0, R, L], and ball bar sensitive direction is rotating shaft coordinate system y positive direction；In pattern three shown in Fig. 2 c, workpiece ball coordinate under stage coordinates system is [0,0, L], and the coordinate of cutter ball is [0,0, L+R], and ball bar sensitive direction is rotating shaft coordinate system z positive direction.Wherein R is ball bar length, L be ball bar workpiece ball to rotating shaft coordinate origin z to distance, M is ball bar workpiece ball to rotating shaft coordinate origin y to distance.Accompanying drawing 2 is the structural representation of these three pattern.

Step 2, according to this five-axle number control machine tool geometric error model, utilize ball bar sensitivity vector, it is thus achieved that the relation between ball bar reading and rotating shaft geometric error, i.e. ball bar reading model.Specific implementation process is as follows.

Five-axle number control machine tool geometrical error modeling process:

(1) for workpiece motion s chain, obtaining workbench homogeneous coordinates in lathe bed coordinate system is:

$T_{\mathrm{pw}}^R=T_A^R\·T_C^A\·T_w^C\·T_{\mathrm{pw}}^w$

WhereinRepresent the A axle homogeneous transform matrix relative to lathe bed；Represent the C axle homogeneous transform matrix relative to A axle；Represent the workbench homogeneous transform matrix relative to C axle, for unit matrix；Represent workpiece homogeneous coordinates under stage coordinates system,Wherein wx, w_y、w_yRepresent workpiece coordinate under stage coordinates system.

(2) for tool motion chain, obtaining point of a knife homogeneous coordinates in lathe bed coordinate system is:

$T_{\mathrm{pt}}^R=T_Y^R\·T_X^Y\·T_Z^X\·T_t^Z\·T_{\mathrm{pt}}^t$

WhereinRepresent the Y-axis homogeneous transform matrix relative to lathe bed；Represent the X-axis homogeneous transform matrix relative to Y-axis；Represent the Z axis homogeneous transform matrix relative to X-axis；Represent the cutter homogeneous transform matrix relative to Z axis, be unit matrix here；Represent point of a knife homogeneous coordinates under tool coordinate system,Wherein t_x、t_y、t_zRepresent point of a knife coordinate under tool coordinate system.

(3) because A axle is all connected on working table movement chain and with workbench with C axle, then geometric error model need to be set up under stage coordinates system.Then all need the homogeneous coordinates obtaining point of a knife under stage coordinates system:

$T_{\mathrm{pt}}^w={(T_A^R\·T_C^A\·T_w^C)}^{-1}\·T_{\mathrm{pt}}^R={(T_A^R\·T_C^{\·A}\·T_w^C)}^{-1}\·T_Y^R\·T_X^Y\·T_Z^X\·T_t^Z\·T_{\mathrm{pt}}^t$

So the geometric error model of this five-axle number control machine tool is:

$V_w=T_{\mathrm{pt}}^w-T_{\mathrm{pw}}^w$

Wherein V_wFor five-axle number control machine tool synthetic geometry error homogeneous vectors.

Ball bar reading model is set up as follows:

(1) the unit homogeneous vectors of ball bar sensitive direction is obtained:

$n={[n_x,n_y,n_z,0]}^T$

Wherein n_x, n_yAnd n_zFor the vectorial coordinate under rotating shaft coordinate system of ball bar sensitivity, it is desirable to $n_x^2+n_y^2+n_z^2=1.$

(2) in conjunction with the geometric error model of five-axle number control machine tool, it is thus achieved that ball bar reading model:

$f=n^T\·V_w-R=n^T\·(T_t^w-T_C^w)-R$

Wherein R is ball bar length, and f is ball bar reading model, n^TTransposed matrix for n.

Step 3, the Installation Modes measured according to the rotating shaft geometric error item comprised in ball bar reading model and each ball bar, to the corresponding parameter combination of each corresponding model selection, come identification obtain each pattern can the expression formula of identification, because the 21 of translation shaft errors can obtain by precision measurement, just using these 21 errors as known come identification rotating shaft geometric error item, including step:

(1), when measuring A axle in pattern one, the axle being synchronized with the movement is A axle, Y-axis and Z axis, then ball bar reading model is:

f_1a=-δ_xa-δ_xx+δ_xy+δ_xz-(Msinα+Lcosα)S_xz

-L·(ε_ya+S_az)+L·ε_yxcosα+N·ε_yxsinα

+l·ε_yycosα+N·ε_yysinα+M·(ε_za+S_ay)

Wherein f_1aA axle ball bar reading in intermediate scheme one；α represents A Shaft angle error；δi_jRepresent the linearity error in j axle i direction；εi_jRepresent the angular errors in j axle i direction；Si_jRepresent the error of perpendicularity of j axle and i axle.Wherein, i, j respectively x, y, z or a；X, y, z, a represent x-axis (direction), y-axis (direction), z-axis (direction) and A axle (direction) respectively, and lower same so ball bar reading model can be deformed into:

r_1a=-δ_xa-L·(ε_ya+S_az)+M·(ε_za+S_ay)(1)

Wherein r_1aCan be described as pattern one and measure ball bar reading total during A axle,

r_1a=g (α, M, L)=f_1a+δ_xx-δ_xy-δ_xa+(Msinα+Lcosα)S_xz

(2)

-L·ε_yxcosα-M·ε_yxsinα-L·ε_yycosα-M·ε_yysinα

Containing 5 A axle geometric error items in formula (1), in conjunction with geometric error item geometric properties, wherein two is vertical error, and for definite value, three is kinematic error, changes along with the change of A Shaft angle.So it is accomplished by three groups of data and carrys out these 5 geometric errors of identification.Selecting first group of parameter is L=L₁And M=0, corresponding ball bar reading isCalculate with formula (2) and obtain total ball bar readingSecond group of parameter is L=L₂And M=0, corresponding reading isCalculate with formula (2) and obtain total ball bar reading3rd group of parameter is L=L₁With M ≠ 0, corresponding reading isCalculate with formula (2) and obtain total ball bar readingThen formula (1) is

$\begin{array}{c}{r}_{1a}^1={-\mathrm{\δ}}_{\mathrm{xa}}-L_1\·({\mathrm{\ϵ}}_{\mathrm{ya}}+{\mathrm{\ϵ}}_{\mathrm{az}})\\ r_{1a}^2={-\mathrm{\δ}}_{\mathrm{xa}}+L_2\·({\mathrm{\ϵ}}_{\mathrm{ya}}+S_{\mathrm{az}})\\ r_{1a}^3={-\mathrm{\δ}}_{\mathrm{xa}}-L_1\·({\mathrm{\ϵ}}_{\mathrm{ya}}+S_{\mathrm{az}})+M\·({\mathrm{\ϵ}}_{\mathrm{za}}+S_{\mathrm{ay}})\end{array}---\left(3\right)$

Wherein, L₁And L₂Represent two different values of L；

Obtaining corresponding A axle geometric error expression formula according to formula (3) identification is

$\begin{array}{c}{S}_{\mathrm{az}}=-\frac{1}{2}(\frac{r_{1a}^1}{L_1}+\frac{r_{1a}^2}{L_2})|\mathrm{\α}=0\\ {\mathrm{\δ}}_{\mathrm{xa}}=\frac{L_2{r}_{1a}^1-L_1{r}_{1a}^2}{L_1-L_2}-\frac{L_2{r}_{1a}^1-L_1-r_{1a}^2}{L_1-L_2}|\mathrm{\α}=0\\ {\mathrm{\ϵ}}_{\mathrm{ya}}=\frac{r_{1a}^2-r_{1a}^1}{L_1-L_2}-S_{\mathrm{az}}-(\frac{r_{1a}^2-r_{1a}^1}{L_1-L_2}-S_{\mathrm{az}})|\mathrm{\α}=0\\ S_{\mathrm{ay}}=\frac{r_{1a}^3+L_1\·S_{\mathrm{az}}}{M}|\mathrm{\α}=0\\ {\mathrm{\ϵ}}_{\mathrm{za}}=\frac{r_{1a}^3+{\mathrm{\δ}}_{\mathrm{xa}}+L_1\·({\mathrm{\ϵ}}_{\mathrm{ya}}+S_{\mathrm{az}})}{M}-S_{\mathrm{zy}}\end{array}---\left(4\right)$

(2), when measuring C axle in pattern one, the axle being synchronized with the movement is C axle, X-axis and Y-axis, then ball bar reading model is:

f_1c=-δ_xc-L·(ε_yc+S_cx)+M·ε_zc+cosγ(δ_xx+δ_xy+δ_xz)

+sinγ(δ_yx+δ_yy+δ_yz)-sinγ(Rcosγ-Msinγ)·(S_xy-ε_zy)

-Lsinγ·(ε_xx+ε_xy+S_yz)+Lcosγ·(ε_yx+ε_yy-S_xz)

Wherein f_1cIntermediate scheme one is measured ball bar reading during C axle；γ represents C Shaft angle error.So ball bar reading model can be deformed into:

r_1c=-δ_xc-L·(ε_yc+S_cx)+M·ε_zc(5)

Wherein r_1cCan be described as total ball bar reading,

r_1c=g (γ, M, L)=f_1c-cosγ(δ_xx+δ_xy+δ_xz]

-sinγ(δ_yx+δ_yy+δ_yz)+sinγ(Rcosγ-Msinγ)·(S_xy-ε_zy)(6)

+Lsinγ·(ε_xx+ε_xy+S_yz)-lcosγ·(εy_x+ε_yy-S_xz)

Containing 4 C axle geometric error items in formula (5), in conjunction with geometric error item geometric properties, one of which is vertical error, and for definite value, three is kinematic error, changes along with the change of C Shaft angle.So it is accomplished by three groups of data and carrys out these 4 geometric errors of identification.Selecting first group of parameter identical with A axle, corresponding ball bar reading isCalculate with formula (6) and obtain total ball bar readingSecond group of parameter is identical with A axle, and corresponding reading isCalculate with formula (6) and obtain total ball bar reading3rd group of parameter is identical with A axle, and corresponding reading isCalculate with formula (6) and obtain total ball bar readingThen formula (5) is

$\begin{array}{c}{r}_{1c}^1={-\mathrm{\δ}}_{\mathrm{xc}}-L_1\·({\mathrm{\ϵ}}_{\mathrm{yc}}+{\mathrm{\ϵ}}_{\mathrm{cx}})\\ r_{1c}^2={-\mathrm{\δ}}_{\mathrm{xc}}+L_2\·({\mathrm{\ϵ}}_{\mathrm{yc}}+S_{\mathrm{cx}})\\ r_{1c}^3={-\mathrm{\δ}}_{\mathrm{xc}}-L_1\·({\mathrm{\ϵ}}_{\mathrm{yc}}+S_{\mathrm{cx}})\end{array}---\left(7\right)$

Obtaining corresponding A axle geometric error expression formula according to formula (7) identification is

$\begin{array}{c}{S}_{\mathrm{cx}}=-\frac{1}{2}\left(\frac{r_{1c}^1+r_{1c}^2}{L_1+L_2}\right)|\mathrm{\γ}=0\\ {\mathrm{\δ}}_{\mathrm{xc}}=\frac{L_2{r}_{1c}^1-L_1{r}_{1c}^2}{L_1-L_2}-\frac{L_2{r}_{1c}^1-L_1{r}_{1c}^2}{L_1-L_2}\\ {\mathrm{\ϵ}}_{\mathrm{yc}}=\frac{r_{1c}^2-r_{1c}^1}{L_1-L_2}-S_{\mathrm{cx}}-(\frac{r_{1c}^2-r_{1c}^1}{L_1-L_2}-S_{\mathrm{cx}})|\mathrm{\γ}=0\\ {\mathrm{\ϵ}}_{\mathrm{za}}=\frac{r_{1c}^3+{\mathrm{\δ}}_{\mathrm{xc}}+L_1\·({\mathrm{\ϵ}}_{\mathrm{yc}}+S_{\mathrm{cx}})}{M}\end{array}---\left(8\right)$

Step 3.2, according to ball bar reading model in pattern two, determine that each rotating shaft needs the geometric error item of identification, geometric properties according to error term, selects two groups of parameters of pattern two, and utilizes corresponding ball bar reading to obtain the expression formula of these geometric error items.Detailed process is:

(1) when measuring A axle in pattern two, ball bar reading model is:

f_2a=-δ_ya+L·ε_xa+cosα(δ_yz+δ_yy)+sinα(δ_zy+δ_zz)

-cosα(Rsinα+Lcosα)·(S_yz+ε_xy)

Wherein f_2aA axle ball bar reading in intermediate scheme two.So ball bar reading model can be deformed into:

r_2a=-δ_ya+L·ε_xa(9)

Wherein r_2aCan be described as ball bar reading total when measuring A axle in pattern two,

r_2a=g (α, L)=f_2a-cosα(δ_yz+δ_yy)-sinα(δ_zy+δ_zz) (10)

+cosα(Rsinα+Lcosα)·(S_yz-+ε_xy)

Containing 2 A axle geometric error items in formula (9), in conjunction with geometric error item geometric properties, these two are kinematic error, change along with the change of A Shaft angle.So it is accomplished by two groups of data and carrys out these 2 geometric errors of identification.Selecting first group of parameter is L=L₁, corresponding ball bar reading isCalculate with formula (10) and obtain total ball bar readingSecond group of parameter is L=L2, and corresponding reading isCalculate with formula (10) and obtain total ball bar readingThen formula (9) is:

$\begin{array}{c}{r}_{2a}^1=-{\mathrm{\δ}}_{\mathrm{ya}}-L_1\·{\mathrm{\ϵ}}_{\mathrm{xa}}\\ r_{2a}^2={-\mathrm{\δ}}_{\mathrm{ya}}+L_2\·{\mathrm{\ϵ}}_{\mathrm{xa}}\end{array}$

So identification can obtain corresponding A axle geometric error expression formula and be

$\begin{array}{c}{\mathrm{\δ}}_{\mathrm{ya}}=\frac{L_2{r}_{2a}^1-L_1{r}_{2a}^2}{L_1{-L}_2}-\frac{L_2{r}_{2a}^1-L_1{r}_{2a}^2}{L_1-L_2}|\mathrm{\α}=0\\ {\mathrm{\ϵ}}_{\mathrm{xa}}=\frac{r_{2a}^1-r_{2a}^2}{L_1-L_2}-\frac{r_{2a}^1-r_{2a}^2}{L_1-L_2}|\mathrm{\α}=0\end{array}---\left(11\right)$

(2) when measuring C axle in pattern two, ball bar reading model is:

f_2c=-δ_yc+L·(ε_xc+S_cy)-sinγ(δ_xx+δ_xy+δ_xz)

+cosγ(δ_yx+δ_yx+δ_yy+δ_yz)+Rcosγsinγ(S_xy-ε_zy)

-Lcosγ·(ε_xx+ε_xy+S_yz)-Lsinγ·(ε_yx+ε_yy-S_xz)

Wherein f_2cC axle ball bar reading in intermediate scheme two.So ball bar reading model can be deformed into:

r_2c=-δ_yc+L·(ε_xc+S_cy)(12)

Wherein r_2cCan be described as ball bar reading total when measuring C axle in pattern two,

r_2c=g (γ, L)=f_2c+sinγ(δ_xx+δ_xy+δ_xz)-cosγ(δ_yx+δ_yy+δyz)

-Rcosγsinγ(S_xy-ε_xy)+Lcosγ·(ε_xx+ε_xy+Syz)(13)

+Lsinγ·(ε_yx+ε_yy-S_xz)

Containing 3 A axle geometric error items in formula (12), in conjunction with geometric error item geometric properties, wherein two is kinematic error, changes along with the change of C Shaft angle, and one is the error of perpendicularity.So it is accomplished by two groups of data and carrys out these 3 geometric errors of identification.Selecting first group of parameter is L=L₁, corresponding ball bar reading isCalculate with formula (13) and obtain total ball bar readingSecond group of parameter is L=L₂, corresponding reading isCalculate with formula (13) and obtain total ball bar readingThen formula (12) is:

$\begin{array}{c}{r}_{2c}^1=-{\mathrm{\δ}}_{\mathrm{yc}}-L_1\·({\mathrm{\ϵ}}_{\mathrm{xc}}+S_{\mathrm{cy}})\\ r_{2a}^2={-\mathrm{\δ}}_{\mathrm{yc}}+L_2\·({\mathrm{\ϵ}}_{\mathrm{xc}}+S_{\mathrm{cy}})\end{array}$

So identification can obtain corresponding C axle geometric error expression formula and be

$\begin{array}{c}{S}_{\mathrm{cy}}=-\frac{1}{2}\left(\frac{r_{2c}^1+r_{2c}^2}{L_1+L_2}\right)|\mathrm{\γ}=0\\ {\mathrm{\δ}}_{\mathrm{yc}}=\frac{L_2{r}_{2c}^1-L_1{r}_{2c}^2}{L_1-L_2}-\frac{L_2{r}_{2c}^1-L_1{r}_{2c}^2}{L_1-L_2}\\ {\mathrm{\ϵ}}_{\mathrm{xc}}=\frac{r_{2c}^2-r_{2c}^1}{L_1-L_2}-S_{\mathrm{cy}}-(\frac{r_{2c}^2-r_{2c}^1}{L_1-L_2}-S_{\mathrm{cy}})|\mathrm{\γ}=0\end{array}---\left(14\right)$

Step 3.3, according to ball bar reading model in pattern three, determine that each rotating shaft needs the geometric error item of identification, geometric properties according to error term, selects one group of group parameter of pattern three, and utilizes corresponding ball bar reading to obtain the expression formula of these geometric error items.Detailed process is:

(1) when measuring A axle in pattern three, ball bar reading model is:

f_3a=-δ_za+(δ_zy+δ_zz)cosα-(δ_yy+δ_yz) sin α (15)

+(L+R)(ε_xy+S_yz)cosαsinα

Wherein f_3aA axle ball bar reading in intermediate scheme three.

Formula (15) contains 1 A axle geometric error item, then have only to one group of data and carry out this 1 geometric error of identification.Selecting this group parameter is L=L₁, corresponding ball bar reading isSo identification can obtain corresponding A axle geometric error expression formula and be

$\begin{array}{c}{\mathrm{\δ}}_{\mathrm{za}}=-f_{3a}^1+({\mathrm{\δ}}_{\mathrm{zy}}+{\mathrm{\δ}}_{\mathrm{zz}})\cos \mathrm{\α}-({\mathrm{\δ}}_{\mathrm{yy}}+{\mathrm{\δ}}_{\mathrm{yz}})\sin \mathrm{\α}\\ +\left(L_{1}R\right)({\mathrm{\ϵ}}_{\mathrm{xy}}+S_{\mathrm{yz}})\cos \mathrm{\α}\sin \mathrm{\α}\end{array}---\left(16\right)$

(2) when measuring C axle in pattern three, ball bar reading model is:

f_3c=-δ_zc+δ_zz(17)

Wherein f_3cC axle ball bar reading in intermediate scheme three.

Formula (17) contains 1 C axle geometric error item, then have only to one group of data and carry out this 1 geometric error of identification.Selecting this group parameter is L=L₁, corresponding ball bar reading isSo identification can obtain corresponding C axle geometric error expression formula and be

${\mathrm{\δ}}_{\mathrm{zc}}={\mathrm{\δ}}_{\mathrm{zz}}-f_{3c}^1---\left(18\right)$

Difference group parameter according to each pattern determined in step 4, combining with digital control machine tool structure selects suitable numerical value to install ball bar, runs lathe according to lathe following function, obtains each group of corresponding ball bar reading of parameter, including step:

Step 4.1, according to this five shafts numerical controlled machine bed structure, select parameter L in pattern one₁=68mm, M=0, R=100mm, install workpiece ball, utilize lathe following function to measure A axle and C axle respectively according to pattern one structure, and record corresponding ball bar readingWith

Step 4.2, utilize according to pattern two structure lathe following function to measure A axle and C axle respectively, and record corresponding ball bar readingWith

Step 4.3, utilize according to pattern three structure lathe following function to measure A axle and C axle respectively, and record every corresponding ball bar readingWith

Step 4.4, according to parameter L in pattern one₁=68mm, M=40mm, R=100mm, install workpiece ball, utilize lathe following function to measure A axle and C axle respectively according to pattern one structure, and record the corresponding ball bar reading of each rotating shaftWith

Step 4.5, according to this five shafts numerical controlled machine bed structure, select parameter L in pattern one₂=90mm, M=0, R=100mm, install workpiece ball, utilize lathe following function to measure A axle and C axle respectively according to pattern one structure, and record corresponding ball bar readingWith

Step 4.6, utilize according to pattern two structure lathe following function to measure A axle and C axle respectively, and record corresponding ball bar readingWith

21 geometric errors of the translation shaft that step 5, the prior laser interferometer measurement of input obtain, according to rotating shaft geometric error item expression formula (4), (8), (11), (13), (14) and (18) and ball bar reading, identification obtains 6 kinematic geometry error terms that 16 geometric errors of two rotating shafts of five-axle number control machine tool, accompanying drawing 3 and accompanying drawing 4 are A axle and C axle.Wherein, Fig. 3 a is 3 linear geometry errors of CAFYXZ Digit Control Machine Tool A axle；Fig. 3 b is 3 corner geometric errors of CAFYXZ Digit Control Machine Tool A axle；Fig. 4 a is 3 linear geometry errors of CAFYXZ Digit Control Machine Tool C axle；Fig. 4 b is 3 corner geometric errors of CAFYXZ Digit Control Machine Tool C axle；The rotating shaft geometric error item obtained with identification and 21 translation shaft errors of measurement, in conjunction with geometric error model, calculate ball bar reading, compare with ball bar reading really, and accompanying drawing 5 is comparative effectiveness figure.Find out that identification precision of the present invention is high.

The present invention finally obtains 16 geometric error items of two rotating shafts of five-axis machine tool.Accompanying drawing is a preferred embodiment; the above embodiments are intended merely to the description present invention, not in order to limit the present invention, all within the spirit and principles in the present invention; any amendment of being made, equivalent replacement, improvement etc., should be included within the protection domain of present aspect.

Claims (7)

1. the rotating shaft geometric error discrimination method that a five-axle number control machine tool is general, it is characterised in that comprise the steps:

Step 1, according to five-axle number control machine tool type, utilize the following function of five-axle number control machine tool, it is determined that three ball bar measurement patterns, including step:

Step 1.1, determining two rotating shaft kinds of five-axle number control machine tool, during for guaranteeing that ball bar is measured, ball bar is static relative to the rotating shaft measured, and utilizes the following function of lathe, it is determined that the machine spindle being synchronized with the movement when measuring rotating shaft, namely determines the axle that is synchronized with the movement；

Step 1.2, according to five-axle number control machine tool rotating shaft kind and the axle that is synchronized with the movement accordingly, it is determined that ball bar measurement pattern, be respectively as follows:

In pattern one, workpiece ball coordinate under rotating shaft coordinate system is [0, M, L], and the coordinate of cutter ball is [R, M, L], and ball bar sensitive direction is rotating shaft coordinate system x positive direction；

In pattern two, workpiece ball coordinate under rotating shaft coordinate system is [0,0, L], and the coordinate of cutter ball is [0, R, L], and ball bar sensitive direction is rotating shaft coordinate system y positive direction；

In pattern three, workpiece ball coordinate under rotating shaft coordinate system is [0,0, L], and the coordinate of cutter ball is [0,0, L+R], and ball bar sensitive direction is rotating shaft coordinate system z positive direction；

Wherein R is ball bar length, L be ball bar workpiece ball to rotating shaft coordinate origin z to distance, M is ball bar workpiece ball to rotating shaft coordinate origin y to distance；

Step 2, according to Geometric Error for Computerized Numerical Control Milling Machine model, utilize ball bar sensitivity vector, it is thus achieved that the relation between ball bar reading and rotating shaft geometric error, i.e. ball bar reading model；

Step 3, according to ball bar reading model and ball bar measurement pattern, in conjunction with the character of rotating shaft geometric error item, it is considered to translation shaft geometric error item, obtain rotary axis of machine tool geometric error item expression formula；

Step 4, according to rotary axis of machine tool geometric error item expression formula and corresponding ball bar measurement pattern, select suitable installation parameter, run lathe according to lathe following function, obtain corresponding ball bar reading；

Step 5, input three translation shaft geometric error items of five-axle number control machine tool, according to rotary axis of machine tool geometric error item expression formula and ball bar reading, identification obtains 16 geometric errors of two rotating shafts of five-axle number control machine tool.

2. the rotating shaft geometric error discrimination method that five-axle number control machine tool according to claim 1 is general, it is characterized in that, in described step 2, five-axle number control machine tool geometric error model need to be converted into the five-axle number control machine tool geometric error model represented under the rotating shaft coordinate system measured, and its ball bar sensitivity vector is homogeneous vectors；Ball bar reading model is obtained according to the five-axle number control machine tool geometric error model after converting and ball bar sensitivity vector.

3. the rotating shaft geometric error discrimination method that five-axle number control machine tool according to claim 1 is general, it is characterised in that when determining rotary axis of machine tool geometric error item expression formula in described step 3, including step:

Step 3.1, according to ball bar reading model in pattern one, determine that each rotating shaft needs the geometric error item of identification, geometric properties according to geometric error item, selects three groups of parameters of pattern one, and utilizes corresponding ball bar reading to obtain the expression formula of described geometric error item；Three groups of described parameters are: L=L₁, M=0, R=R；L=L₂, M=0, R=R；And L=L₁, M ≠ 0, R=R；Wherein L₁≠L₂；

Step 3.2, according to ball bar reading model in pattern two, determine that each rotating shaft needs the geometric error item of identification, geometric properties according to geometric error item, selects two groups of parameters of pattern two, and utilizes corresponding ball bar reading to obtain the expression formula of described geometric error item；These described two groups of parameters are: L=L₁, R=R；And L=L₂, R=R；Wherein L₁≠L₂；

Step 3.3, according to ball bar reading model in pattern three, determine that each rotating shaft needs the geometric error item of identification, geometric properties according to geometric error item, selects one group of parameter of pattern three, and utilizes corresponding ball bar reading to obtain the expression formula of described geometric error item；This described group parameter is: L=L₁, R=R.

4. the rotating shaft geometric error discrimination method that five-axle number control machine tool according to claim 3 is general, it is characterised in that determine each group of corresponding ball bar reading of parameter in described step 4, including step:

Step 4.1, according to parameter L=L in pattern one₁, M=0, R=R installs workpiece ball, utilizes lathe following function to measure two rotating shafts respectively according to pattern one structure, and records each rotating shaft this group parameter ball bar reading corresponding

Step 4.2, utilize according to pattern two structure lathe following function to measure two rotating shafts respectively, and record each rotating shaft this group parameter ball bar reading corresponding

Step 4.3, utilize according to pattern three structure lathe following function to measure two rotating shafts respectively, and record each rotating shaft this group parameter ball bar reading corresponding

Step 4.4, according to parameter L=L in pattern one₁, M ≠ 0, R=R installs workpiece ball, utilizes lathe following function to measure two rotating shafts respectively according to pattern one structure, and records each rotating shaft this group parameter ball bar reading corresponding

Step 4.5, according to parameter L=L in pattern one₂, M=0, R=R installs workpiece ball, utilizes lathe following function to be separately operable two rotating shafts and its axle that is synchronized with the movement accordingly according to pattern one structure, and records each rotating shaft this group parameter ball bar reading corresponding

Step 4.6, utilize according to pattern two structure lathe following function to measure two rotating shafts and its axle that is synchronized with the movement accordingly respectively, and record each rotating shaft this group parameter ball bar reading corresponding

WhereinWhich group parameter middle subscript represents；Subscript 1,2,3 is pattern one, pattern two, pattern three respectively；I represents rotating shaft type.

5. the rotating shaft geometric error discrimination method that five-axle number control machine tool according to claim 1 is general, it is characterised in that 21 geometric error items of the lathe translation shaft of input in described step 5, it is possible to obtain with laser interferometer measurement.

6. the rotating shaft geometric error discrimination method that five-axle number control machine tool according to any one of claim 1-5 is general, it is characterised in that described five-axle number control machine tool is CAFYXZ type five-axle number control machine tool.

7. the rotating shaft geometric error discrimination method that five-axle number control machine tool according to claim 6 is general, it is characterised in that in step (2), two rotating shaft types of five-axle number control machine tool are A axle and C axle；The axle that is synchronized with the movement when determining measurement A axle is A axle, Y-axis and Z axis, and the axle that is synchronized with the movement when measuring C axle is C axle, X-axis and Y-axis.