CN105717864A - Numerically-controlled machine tool comprehensive error three-stage optimized compensation method on basis of modifying NC program - Google Patents

Abstract

The invention belongs to the field of multi-axis numerically-controlled machine tool comprehensive error compensation key technology research, and aims at solving the problem that in the prior art, a multi-axis numerically-controlled machine tool of which the machining precision is greatly reduced after being used for a long time is lack of a universal error compensation method.The invention provides a three-stage optimized numerically-controlled machine tool motion error offline compensation method, wherein three stages of optimization comprise a segmented refinement stage, a segmented optimization stage and a deep optimization stage.The method particularly comprises the following steps that on the basis of an existing NC program, a starting point position and a terminating point position of motion of a feed shaft or a main shaft are read in corresponding program lines, and segmented refinement is conducted on the track; all key point positions on the track are calculated, corresponding errors are obtained by applying a numerically-controlled machine tool position and posture prediction model, and primary optimization is conducted on the key point positions; iterative computation, taking a preset precision value as a constraint condition, is conducted on optimized point positions to achieve deep optimization.The method has good universality on multi-axis linkage numerically-controlled machine tools of different control systems.

Description

Digit Control Machine Tool synthetic error three rank Optimization Compensation method based on amendment NC program

Technical field

The invention belongs to multi-axis NC Machine Tools comprehensive error compensation key technology research field, former particularly to one amendment The multi-shaft linkage numerical control machine synthetic error off-line compensation method of NC processor.

Background technology

Multi-shaft linkage numerical control machine comprehensive error compensation is always the study hotspot of digital control processing and field of intelligent control.Number The error compensating method of control lathe is broadly divided into hardware error and compensates and Software error compensation.Hardware error compensation method, mainly It is for numerically-controlled machine tool system, regularity, repeatably error term, is become by the error detecting each relative motion through-drive chain Change curve, calculate the straightening mechanism complementary with former drive disk assembly, it is achieved error compensation, the method is to different kinematic axiss Needing to design specific compensation device with different lathes, versatility is poor and relatively costly.In recent years, Software error compensation side Method becomes NC Machine Error and compensates main direction of studying.Based on neutral net, gray theory, Multibody Kinematics, time Sequence and ant group algorithm theories and methods, researchers propose various compensation method.[Zhang Qiuju, Zhao Yiding, Mao Jun Red, Lin Qijun. Fuzzy Self-learning error compensating method and the application [J] in positional error compensation thereof. Xi'an Communications University is learned Report, 1995,29 (2): 67-72.], this document propose Software error compensation method the successful Application of a kind of Fuzzy Self-learning In the positional error compensation of open-loop NC system, its feature is according to error and rate of change thereof, carries out fuzzy reasoning and obtains by mistake Difference correction value, uses self study technology to generate error correction table.[Hsu YY,Wang SS.A new compensation method for geometry errors of five-axis machine tools[J].International Journal of Machine Tools and Manufacture, 2007,47 (2): 352-360.], the document is according to numerical control The forward inverse kinematics equation of lathe calculates linear axes error after first calculating rotary shaft error by decoupling method, passes through Amendment NC code realizes mismachining tolerance and compensates.[Fu Jianzhong pays Guoqiang, He Yong, Lin Zhiwei. and a kind of based on part model reconstruction Three axis numerically controlled machine geometric error compensation method [P]. China: patent of invention, CN104057363A, 2014.06.10], this Bright disclose a kind of based on part model rebuild Geometric Error for Computerized Numerical Control Milling Machine compensation method, use Isoparametric method obtain workpiece table Each point coordinates substitute into error model and be modified on face, rebuilds part model according to revised each key point, by workpiece Initial point generates corresponding machining path and code as program origin, it is achieved the compensation to Geometric Error for Computerized Numerical Control Milling Machine.

Although existing various multiple theories and the research of method, but big for those long service post-treatment precision The multi-axis NC Machine Tools of width decay also lacks general error compensating method.

Summary of the invention

The invention aims to solve, in prior art, significantly to decay many for long service post-treatment precision The problem that Shaft and NC Machining Test lathe lacks general error compensating method.

For reaching above-mentioned purpose, the present invention provides a kind of Digit Control Machine Tool synthetic error three rank based on amendment NC program to optimize Compensation method, it is achieved the synthetic error off-line of Digit Control Machine Tool working motion compensates, thus improves machining accuracy.The method concrete Step is as follows:

Theoretical and the topological structure of lathe according to Multibody Kinematics, sets up multi-axis NC Machine Tools position and attitude error prediction mould Type；

NC program based on workpiece to be processed, reads the starting point and ending point of feed shaft motion, calculates starting point and end Distance between stop, if described distance produces the error error threshold more than setting, then carries out error three rank Optimization Compensation also Revise described NC program；

Amended NC program is imported multi-axis NC Machine Tools servo-control system, carries out actual Milling Process.

Specifically, the concrete grammar carrying out three rank Optimization Compensations is as follows:

Segmentation refines: feed shaft or main shaft starting point position are set to N₁(X₁,Y₁,Z₁), terminating point position is set to N_n(X_n,Y_n, Z_n), by preferred numbers increment, the track of starting point to terminating point is divided into n-1 section, its each point position N_i(X_i,Y_i,Z_i) as the following formula Obtain:

$\left\{\begin{array}{c}{\left(X_i-X_1\right)}^2+{\left(Y_i-Y_1\right)}^2+{\left(Z_i-Z_1\right)}^2={\left(rt\right)}^2\\ X_i=(X_n-X_1)t+X_1;X_1<X_i<X_n\\ Y_i=(Y_n-Y_1)t+Y_1;Y_1<Y_i<Y_n\\ Z_i=(Z_n-Z_1)t+Z_1;Z_1<Z_i<Z_n\end{array}\right.,$

Wherein, rt is the growth factor of preferred numbers, t Yu r is positive number, and i is the value positive integer from 1 to n；

Segmentation just suboptimization: each position coordinate described is substituted into formula

$N_{i,p}^e{(x_i,y_i,z_i)}^T=T_p^e{}_T{}^W\&CenterDot;N_{i-1,p}{(x_{i-1},y_{i-1},z_{i-1})}^T---1)$

After, by calculatedSubstitute into formula

${N_i}^{\&prime;}({X_i}^{\&prime;},{Y_i}^{\&prime;},{Z_i}^{\&prime;})=N_i(X_i,Y_i,Z_i)-\left(N_{i,p}^e\right(x_i,y_i,z_i)-N_i(X_i,Y_i,Z_i\left)\right)---2);$

Depth optimization: by calculated N_i'(X_i',Y_i',Z_i') substitute into formula 1) and 2), in constraints | N_i”(X_i”, Y_i”,Z_i”)-N_i'(X_i',Y_i',Z_i')|≤ε₁Under be iterated calculating and realize depth optimization, wherein, ε₁Represent error threshold.

Specifically, when walking instruction in advance for G00, owing to this instruction is without the concern for intermediate track, therefore according to above-mentioned side Method carries out error off-line compensation.

A kind of particular situation is, for linear interpolation NC instruction G01, after carrying out three rank Optimization Compensations, by described respectively The direction of individual some position compares with the direction of this section of straight line in the NC program read, and concrete grammar is as follows:

RelativelyWithSize,

When a minimum, X_i" for retaining benchmark,

Obtain new position coordinate N_i”(X_i”,Y_i”,Z_i"),

When b minimum, Y_i" for retaining benchmark,

Obtain new position coordinate N_i”(X_i”,Y_i”,Z_i"),

When c minimum, Z_i" for retaining benchmark,

Obtain new position coordinate N_i”(X_i”,Y_i”,Z_i”)。

Another kind of particular situation is to instruct G02/03 for arc track interpolation, and its three rank Optimization Compensation method is concrete As follows:

It is located in the plane that G17 instruction is arranged, according to formula

$r=\sqrt{I^2+J^2}$

Calculate this section of former arc radius of ideal, according to formula

$\left|D_1{D}_2\right|=\sqrt{{(X_2-X_1)}^2+{(Y_2-Y_1)}^2}$

Calculate chord length, according to formula

$\left\{\begin{array}{c}{\mathrm{\&alpha;}}_1=\arccos \left(\frac{X_1-X_o}{r}\right);0<{\mathrm{\&alpha;}}_1<\mathrm{\&pi;}\\ {\mathrm{\&alpha;}}_2=\arccos \left(\frac{X_2-X_o}{r}\right);0<{\mathrm{\&alpha;}}_2<\mathrm{\&pi;}\\ \mathrm{\&alpha;}=\&PlusMinus;({\mathrm{\&alpha;}}_2-{\mathrm{\&alpha;}}_1)\end{array}\right.$

Calculate angle, wherein, when instruction for G02 time, α takes "-", when instruction for G03 time, α take "+"；

Segmentation refines: according to preferred numbers, uses the mode of center of circle angle step, determines circular arc | D₁D₂N pass on | Key point position, carries out segmentation refinement to this section of circular curve, method particularly includes: set this section of circular arc starting point position D₁(X₁,Y₁,Z₁) it is N₁ (X₁,Y₁,Z₁), terminating point position D₂(X₂,Y₂,Z₂) it is N_n(X_n,Y_n,Z_n), and press formula

$\left\{\begin{array}{c}{X}_i=X_1+rcos({\mathrm{\&alpha;}}_1\&PlusMinus;\mathrm{\&theta;})\\ Y_i=Y_1+r\cos ({\mathrm{\&alpha;}}_1\&PlusMinus;\mathrm{\&theta;})\end{array}\right.$

Calculate key point coordinate N_i(X_i,Y_i), when instruction is for G02, take "-", when instruction is for G03, take "+", θ For angle step；

Subsection optimization: according to formula

$\left\{\begin{array}{c}\left\{\begin{array}{c}{X}_i=X_1+r\cos ({\mathrm{\&alpha;}}_1\&PlusMinus;\mathrm{\&theta;})\\ Y_i=Y_1+r\cos ({\mathrm{\&alpha;}}_1\&PlusMinus;\mathrm{\&theta;})\end{array}\right.\\ Z_i=Z_1+{\mathrm{\&Delta;Z}}_i=Z_1+\mathrm{\&theta;}\left(\frac{Z_2-Z_1}{\mathrm{\&alpha;}}\right)\end{array}\right.$

It is calculated each key point coordinate N_i(X_i,Y_i,Z_i), and each key point coordinate is substituted into formula 1), meter Calculate feed shaft or the actual arc track passed by of main shaft, more each key point actual coordinate value substituted into formula 2), carry out point Duan Youhua；

Depth optimization: gained is respectively optimized key point place value as initial value, substitution formula 1) and formula 2) in constraints | N_i”(X_i”,Y_i”,Z_i”)-N_i'(X_i',Y_i',Z_i')|≤ε₂Under be iterated calculating and realize depth optimization, wherein, ε₂Represent error Threshold value.

G02/03 is instructed for arc track interpolation, further, after carrying out depth optimization, according to formula

$\left\{\begin{array}{c}{I}_i^{\&prime;}=X_o-X_{i-1}^{\&prime;}\\ J_i^{\&prime;}=Y_o-Y_{i-1}^{\&prime;}\end{array}\right.$

The center of circle is corrected, (I_i', J_i') represent the central coordinate of circle after correcting.

G02/03 is instructed for arc track interpolation, further, for carrying out the some place value after depth optimization, also wraps Include:

CalculateWork as Δ > ε₃Time, according to formula

To amended key Point position is further revised, wherein, and ε₃Represent error threshold.

In the present invention, if walking the motion comprising swinging axle in instruction in advance, then:

Between this section of track, insert point midway refine key point, point midway N as segmentation_1.5(X_1.5,Y_1.5,Z_1.5) Coordinate calculation method is:

$\left\{\begin{array}{c}{N}_i(X_i,Y_i,Z_i)=\frac{1}{2}\left(N_1\right(X_1,Y,Z_1)+N_2(X_2,Y_2,Z_2\left)\right)\\ N_i(A_i,B_i)=\frac{1}{2}\left(N_1\right(A_1,B_1)+N_2(A_2,B_2\left)\right)\end{array}\right.;$

Will a position N_1.5(X_1.5,Y_1.5,Z_1.5)、N_1.5(A_1.5,B_1.5) and N₂(X₂,Y₂,Z₂)、N₂(A₂,B₂) substitute into formula 1) and Formula 2), it is achieved first suboptimization obtains a position N_i'(X_i',Y_i',Z_i') and N_i'(A_i',B_i')；

Will position, a site N_i'(X_i',Y_i',Z_i') and N_i'(A_i',B_i') substitute into formula 1) and formula 2), in constraintsUnder be iterated computing and realize depth optimization, obtain correction value N_i”(X_i”,Y_i”,Z_i”) With N_i”(A_i”,B_i"), wherein, ε₄Represent error threshold.

The invention has the beneficial effects as follows: Digit Control Machine Tool synthetic error three rank based on amendment NC program of the present invention optimize mends Compensation method, while need not update Digit Control Machine Tool hardware device and increase cost input, optimizes Digit Control Machine Tool synthetic error Compensate and improve machining accuracy.In the wherein measurement of error and the identification stage, need according to high precision double frequency laser interferometer and ball Bar instrument feed shaft each to multi-axis NC Machine Tools and main shaft carry out comprehensive error measure and identification, provide for three rank Optimization Compensation methods Reliably foundation.Use this three rank Optimization Compensation method efficiency simple to operate high.

Accompanying drawing explanation

Fig. 1 is the multi-axis NC Machine Tools synthetic error three rank Optimization Compensation method flow diagram of embodiment；

Fig. 2 is that the off-line type of the A/B double-swinging angle gantry numerical control milling machine synthetic error of embodiment compensates three rank optimization method behaviour Make flow chart；

Fig. 3 is certain type workpiece numerical-controlled processing NC program of embodiment；

Fig. 4 is certain type workpiece amended numerical control NC program of embodiment.

Detailed description of the invention

Below in conjunction with drawings and Examples, technical scheme is described in further detail, it is noted that Embodiment is only used to help reader to be best understood from the technology design of the present invention and the application example that enumerates, and it is not in order to limit Determine protection scope of the present invention.Those skilled in the art make various real without departing from the present invention according to the technology of the present invention method e nlightenment Other various error compensating methods of matter or do the method for simple change all will be within the scope of the present invention.

The present invention is directed in prior art, the multi-axis NC Machine Tools that long service post-treatment precision significantly decays lacks logical The problem of error compensating method, it is provided that the three rank optimization Digit Control Machine Tools of a kind of " segmentation refinement-subsection optimization-depth optimization " Kinematic error off-line compensation method.Hereby method is based on existing NC program, reads feed shaft or main shaft from corresponding program line The starting point position of motion and terminating point position, carry out segmentation refinement by this section of track；Calculate each key point on this path And use Digit Control Machine Tool pose forecast model to obtain its corresponding error, key point is carried out just suboptimization；After optimizing Point position carries out the iterative computation with predetermined accuracy value as constraints to realize depth optimization.For to track road in concrete operations Footpath does not has the G00 of constraint requirements to instruct, and is optimized according to the method described above；For linear interpolation NC instruction G01, for the degree of depth The key point obtained after optimization, carries out rectilinear direction vector correction；G02/03 is instructed for arc track interpolation, for the degree of depth Key point after optimization, for ensureing the constant smoothness (reduction curvature variation) with circular arc of home position, be to position, the center of circle Put and be corrected, finally give compensation point position.Modifying NC program according to this, the error compensation for workpiece is processed, from And realize the soft upgrading of machine finish.

As it is shown in figure 1, the Digit Control Machine Tool synthetic error three rank Optimization Compensation method based on amendment NC program of the present invention, step Rapid as follows: first, multi-axis NC Machine Tools to be carried out error measure and identification, measure respectively the shifting axle of multi-axis NC Machine Tools with The error of swinging axle, sets up the error chart of described every error；Secondly, opening up of theoretical according to Multibody Kinematics and lathe Flutter structure, set up multi-axis NC Machine Tools position and attitude error forecast model；Then, NC program based on workpiece to be processed, reads feeding The starting point and ending point of axle motion, calculates the distance between starting point and terminating point, if described distance produces error more than setting Fixed error threshold, then carry out error three rank Optimization Compensation and revise described NC program；Finally, amended NC program is imported Multi-axis NC Machine Tools servo-control system, carries out actual Milling Process.

Embodiment

Use the method for the present invention to carry out error compensation large-scale A/B double-swinging angle 5-shaft linkage numerical control planer-type milling machine below to enter The exemplary description of row, before using the method for the present invention, workpiece numerical-controlled processing NC program is as shown in Figure 3.

Large-scale A/B double-swinging angle 5-shaft linkage numerical control planer-type milling machine is carried out synthetic error measurement and identification, and sets up its position Appearance error prediction modular form 3) as follows

NC program based on certain type part, when reading following program segment, according to Fig. 2, carries out error compensation.

N35 X35.Y-55.Z0.

N40 G00 X35.Y-55.Z15.

If original some position D₁(X₁,Y₁,Z₁) and D₂(X₂,Y₂,Z₂)；Distance between first calculating at 2, such as following formula

$\left|D_1{D}_2\right|=\sqrt{{(X_2-X_1)}^2+{(Y_2-Y_1)}^2+{(Z_2-Z_1)}^2}=15mm>2mm.$

In order to make feed process uniformly and arrive ideal position, this segment distance is carried out point by the mode that preferred numbers increases Section refinement also calculates key point.Key point is as follows；N₁(35,-55,0)；N₂(35,-55,1)；N₃(35,-55,2.6)； N₄(35,-55,5.1)；N₅(35,-55,9.1)；N₆(35,-55,15)。

These key points are substituted into error prediction modular form 3) and formulaCalculate actual point Position:

N'₁(35,-55,0)；N'₂(35.0524,-54.9666,0.9351)；N'₃(35.0510,-54.9690, 2.5371)；N'₄(35.0481,-54.9731,5.0428)；N'₅(35.0480,-54.9755,9.0488)；N'₆ (35.0592,-54.9735,14.9392)。

Above-mentioned each key point is substituted into error compensation type formula

This segment distance is made to obtain subsection optimization.

N'₁(35,-55,0)；N'₂(35.0524,-54.9666,1.0649)；N'₃(35.0510,-54.9690, 2.6629)；N'₄(35.0483,-54.9731,5.1572)；N'₅(35.0480,-54.9755,9.1512)；N'₆ (35.0592,-54.9735,15.0608)。

Owing to code command G00 does not consider cutter path, therefore depth optimization is only needed to put position the whole story.Substitution formula | N_i” (X_i”,Y_i”,Z_i”)-N_i'(X_i',Y_i',Z_i')|≤ε₁Obtain after calculating:

N'₁(35,-55,0)；N'6(35,-55,15.0022).

Utilize the processing stand position after optimizing, regenerate the NC processor with error compensation function.As follows:

N35 X35.Y-55.Z0.

N36 G00 X35.0524 Y-54.9666 Z1.0649

N37 X35.0510 Y-54.9690 Z2.6629

N38 X35.0483 Y-54.9731 Z5.1572

N39 X35.0480 Y-54.9755 Z9.1512

N40 X35.Y-55.Z15.0022

So, refine the route that cutter is passed by, it is possible to final optimization pass cutter path, obtain the higher workpiece of precision.

When running into following program segment, owing to G01 is linear interpolation instruction, then for it is also contemplated that during its subsection optimization It is straight line to cutter path.

N50 X0.Y-54.Z-3.

N55 G01 X10.Y-55.F4.

If original some position D₁(X₁,Y₁,Z₁) and D₂(X₂,Y₂,Z₂, the first distance between calculating 2, such as following formulaAnd the direction of straight line is

Carry out segmentation refinement according to preferred numbers increment and obtain corresponding key point:

N₁(0,-54,-3)；N₂(1,-54.1,-3)；N₃(2.6,-54.26,-3)；N₄(5.1,-54.51,-3)；N₅ (9.1,-54.91,-3)；N₆(10,-55,-3)。

These key points are substituted into error prediction modular form 3) andCalculate Go out actual point position:

N'₁(0,-54,-3)；N'₂(1.0387,-54.0967,-3.0413)；N'₃(2.6168,-54.2572,- 3.0267)；N'₄(5.0808,-54.5104,-2.9917)；N'₅(9.0727,-54.9133,-2.9645)；N'₆ (10.0422,-54.9893,-3.0507)。

Above-mentioned each key point is substituted into error compensation type

This section of straight line is made to be optimized:

N'₁(0,-54,-3)；N'₂(0.9613,-54.1033,-2.9587)；N'₃(2.5832,-54.2628,- 2.9733)；N'₄(5.1192,-54.5096,-3.0083)；N'₅(9.1273,-54.9067,-3.0355)；N'₆(9.9578,- 55.0107,-2.9493)；

After above-mentioned each key point is carried out depth optimization it is:

N'₁(0,-54,-3)；N'₂(0.9728,-54.1102,-3.021)；N'₃(2.6113,-54.2635,- 2.9762)；N'₄(5.1089,-54.5199,-3.0102)；N'₅(9.1173,-54.9099,-3.0015)；N'₆(9.9968,- 55.0021,-2.9596)。

On these some positions are not desirably distributed in and are intended to take the air line, and it is aligned in around straight line, needs it is carried out line Property correction for direction.After correction it is:

N'₁(0,-54,-3)；N'₂(0.9728,-54.0972,-3)；N'₃(2.6113,-54.2611,-3)；N'₄ (5.1089,-54.5108,-3)；N'₅(9.099,-54.9099,-3)；N'₆(9.9968,-54.9996,-3)。

The most amended NC program is:

N50 X0.Y-54.Z-3.

N51 G01 X0.9728 Y-54.0972 F4.

N52 X2.6113 Y-54.2611

N53 X5.1089 Y-54.5108

N54 X9.099 Y-54.9099

N55 X9.9968 Y-54.9996

When running into following program segment, owing to G02 represents circular curve interpolation clockwise track, depth optimization to be considered The center of circle of rear circular arc is constant.

N115 G17 G01 X34.Y-50.

N120 G02 X30.Y-54.I-4.J0.

Starting point D of circular arc₁(34 ,-50), terminating point D₂(30 ,-54), also central coordinate of circle D_o(30,-50)。

Radius:Chord length:

Angle:Central angle:

This section of circular arc is found and is carried out segmentation refinement, find the corresponding key point to be:

N₁(34,-50)；N₂(33.9392,-50.6946)；N₃(33.5952,-51.7535)；N₄(32.5173,- 53.1086)；N₅(30,-54)。

These key points are substituted into position and attitude error forecast model formula 3) and

Calculate actual point position:

N₁(34,-50)；N₂(33.9848,-50.6630)；N₃(33.6349,-51.7263)；N₄(32.3314,- 53.0989)；N₅(29.9652,-54.0211)。

Above-mentioned each key point is substituted into error compensation type

This section of circular arc is made to be optimized:

N₁(34,-50)；N₂(33.8936,-50.7262)；N₃(33.5555,-51.7807)；N₄(32.7032,- 53.1183)；N₅(30.0348,-53.9789)。

After above-mentioned each key point is carried out depth optimization it is:

N₁(34,-50)；N₂(33.9026,-50.7114)；N₃(33.5622,-51.7447)；N₄(32.6620,- 53.1100)；N₅(29.8849,-54.0244)。

In order to the center of circle of the circular curve after making correction does not changes, the corresponding I/J value going out each key point is done suitable Work as correction:

I₂(-4,0)；I₃(-3.9026,0.7114)；I₄(-3.5622,1.7447)；I₅(-2.6620,3.1100)。

The most amended NC program is:

N115 G17 G01 X34.Y-50.

N116 G02 X33.9026 Y-50.7114 I-4.J0.

N117 X33.5622 Y-51.7447 I-3.9026 J0.7114

N118 X32.6620 Y-53.1100 I-3.5622 J1.7447

N119 X29.8849 Y-54.0244 I-2.6620 J3.1100

When running into following program segment, while existing linear axes is moved, add the fortune of two swinging axle A/B Dynamic.

N1460 X-0.1307 Y-37.0433 Z-63.0776 A354.332 B3.693

N1470 X-0.734 Y-35.8036 Z-62.8532 A354.518 B3.628

If this geometric locus starting point position N₁(-0.1307 ,-37.0433 ,-63.0776), terminating point

N₂(-0.734 ,-35.8036 ,-62.8532),

This section of track is carried out segmentation refinement, finds the corresponding key point to be:

N₁(-0.1307 ,-37.0433 ,-63.0776),

N_1.5(-0.43235 ,-36.42345 ,-62.9654), N₂(-0.734 ,-35.8036 ,-62.8532),

Above-mentioned each key point is substituted into position and attitude error forecast model formula 3) and

Calculate actual point position:

N₁(-0.1307 ,-37.0433 ,-63.0776),

N_1.5(-0.5114 ,-36.5289 ,-62.8824),

N₂(-0.7424,-35.7787,-62.8673)

Above-mentioned each key point is substituted into error compensation type

This section of track is made to be optimized:

N₁(-0.1307 ,-37.0433 ,-63.0776),

N_1.5(-0.3533 ,-36.314 ,-63.0484),

N₂(-0.7256,-35.8285,-62.8391)

After above-mentioned each key point is carried out depth optimization it is:

N₁(-0.1307 ,-37.0433 ,-63.0776),

N_1.5(-0.4022 ,-36.3955 ,-63.01127),

N₂(-0.72299,-35.8117,-62.8458)

The intermediate change position of generating tool axis vector on this section of track is refined, finds the corresponding key point to be:

N₁(354.332,3.693), N_1.5(354.425,3.6605), N₂(354.518,3.628)

Above-mentioned each key point is substituted into position and attitude error forecast model formula 3) andCalculate Go out actual point position:

N₁(354.332,3.693), N_1.5(354.4468,3.6322), N₂(354.5541,3.6221)

Above-mentioned each key point is substituted into error compensation type

This section of track is made to be optimized:

N₁(354.332,3.693), N_1.5(354.4035,3.6888), N₂(354.4719,3.6339)

After above-mentioned each key point is carried out depth optimization it is:

N₁(354.332,3.693), N_1.5(354.4429,3.6624), N₂(354.4952,3.6331)

The most amended NC program is:

N1460 X-0.1307 Y-37.0433 Z-63.0776 A354.332 B3.693

N1465 X-0.4022 Y-36.3955 Z-63.01127 A354.4429 B3.6624

N1470 X-0.72299 Y-35.8117 Z-62.8458 A354.4952 B3.6331。

After realizing three rank optimizations of key point according to the method described above, amendment NC program realizes the error off-line of Digit Control Machine Tool Compensating, amended numerical control NC program is as shown in Figure 4.

Claims (7)

1. Digit Control Machine Tool synthetic error three rank Optimization Compensation method based on amendment NC program, it is characterised in that include walking as follows Rapid:

According to Multibody Kinematics, the theoretical and topological structure of lathe, sets up multi-axis NC Machine Tools position and attitude error forecast model；

NC program based on workpiece to be processed, reads the starting point and ending point of feed shaft motion, calculates starting point and terminating point Between distance, if described distance produce error more than set error threshold, then combine described error chart and carry out error Three rank Optimization Compensations also revise described NC program；

Amended NC program is imported multi-axis NC Machine Tools servo-control system, carries out actual Milling Process.

2. Digit Control Machine Tool synthetic error three rank Optimization Compensation method based on amendment NC program as claimed in claim 1, it is special Levying and be, the concrete grammar carrying out three rank Optimization Compensations is as follows:

Segmentation refines: feed shaft or main shaft starting point position are set to N₁(X₁,Y₁,Z₁), terminating point position is set to N_n(X_n,Y_n,Z_n), press The track of starting point to terminating point is divided into n-1 section by preferred numbers increment, its each point position N_i(X_i,Y_i,Z_i) obtain as the following formula:

$\left\{\begin{array}{c}{(X_i-X_1)}^2+{(Y_i-Y_1)}^2+{(Z_i-Z_1)}^2={\left(rt\right)}^2\\ X_i=(X_n-X_1)t+X_1;X_1<X_i<X_n\\ Y_i=(Y_n-Y_1)t+Y_1;Y_1<Y_i<Y_n\\ Z_i=(Z_n-Z_1)t+Z_1;Z_1<Z_i<Z_n\end{array}\right.,$

Wherein, rt is the growth factor of preferred numbers, t Yu r is positive number, and i is the value positive integer from 1 to n；

Segmentation just suboptimization: each position coordinate described is substituted into formula

$N_{i,p}^e{(x_i,y_i,z_i)}^T=T_p^e{}_T{}^W\&CenterDot;N_{i-1,p}{(x_{i-1},y_{i-1},z_{i-1})}^T---1)$

After, by calculatedSubstitute into formula

$N_i^{\&prime;}(X_i^{\&prime;},Y_i^{\&prime;},Z_i^{\&prime;})=N_i(X_i,Y_i,Z_i)-\left(N_{i,p}^e\right(x_i,y_i,z_i)-N_i(X_i,Y_i,Z_i\left)\right)---2);$

Depth optimization: by calculated N_i'(X_i',Y_i',Z_i') substitute into formula 1) and 2), in constraints | N_i”(X_i”,Y_i”, Z_i”)-N_i'(X_i',Y_i',Z_i')|≤ε₁Under be iterated calculating and realize depth optimization, wherein, ε₁Represent error threshold.

3. Digit Control Machine Tool synthetic error three rank Optimization Compensation method based on amendment NC program as claimed in claim 2, it is special Levy and be, for linear interpolation NC instruction G01, after carrying out three rank Optimization Compensations, by described each some position direction with read In the NC program taken, the direction of this section of straight line compares, and concrete grammar is as follows:

RelativelyWithSize,

When a minimum, X_i" for retaining benchmark,

Obtain new position coordinate N_i”(X_i”,Y_i”,Z_i"),

When b minimum, Y_i" for retaining benchmark,

Obtain new position coordinate N_i”(X_i”,Y_i”,Z_i"),

When c minimum, Z_i" for retaining benchmark,

Obtain new position coordinate N_i”(X_i”,Y_i”,Z_i”)。

4. Digit Control Machine Tool synthetic error three rank Optimization Compensation method based on amendment NC program as claimed in claim 2, it is special Levying and be, instruct G02/03 for arc track interpolation, its three rank Optimization Compensation method is specific as follows:

It is located in the plane that G17 instruction is arranged, according to formula

$r=\sqrt{I^2+J^2}$

Calculate this section of former arc radius of ideal, according to formula

$\left|D_1{D}_2\right|=\sqrt{{(X_2-X_1)}^2+{(Y_2-Y_1)}^2}$

Calculate chord length, according to formula

$\left\{\begin{array}{c}{\mathrm{\&alpha;}}_1=arccos\left(\frac{X_1-X_o}{r}\right);0<{\mathrm{\&alpha;}}_1<\mathrm{\&pi;}\\ {\mathrm{\&alpha;}}_2=arccos\left(\frac{X_2-X_o}{r}\right);0<{\mathrm{\&alpha;}}_2<\mathrm{\&pi;}\\ \mathrm{\&alpha;}=\&PlusMinus;({\mathrm{\&alpha;}}_2-{\mathrm{\&alpha;}}_1)\end{array}\right.$

Calculate angle, wherein, when instruction for G02 time, α takes "-", when instruction for G03 time, α take "+"；

Segmentation refines: according to preferred numbers, uses the mode of center of circle angle step, determines circular arc | D₁D₂N key point on | Position, carries out segmentation refinement to this section of circular curve, method particularly includes: set this section of circular arc starting point position D₁(X₁,Y₁,Z₁) it is N₁(X₁, Y₁,Z₁), terminating point position D₂(X₂,Y₂,Z₂) it is N_n(X_n,Y_n,Z_n), and press formula

$\left\{\begin{array}{c}{X}_i=X_1+rcos({\mathrm{\&alpha;}}_1\&PlusMinus;\mathrm{\&theta;})\\ Y_i=Y_1+r\cos ({\mathrm{\&alpha;}}_1\&PlusMinus;\mathrm{\&theta;})\end{array}\right.$

Calculate key point coordinate N_i(X_i,Y_i), when instruction is for G02, take "-", when instruction is for G03, take "+", θ is angle Degree increment；

Subsection optimization: according to formula

$\left\{\begin{array}{c}\left\{\begin{array}{c}{X}_i=X_1+r\cos ({\mathrm{\&alpha;}}_1\&PlusMinus;\mathrm{\&theta;})\\ Y_i=Y_1+r\cos ({\mathrm{\&alpha;}}_1\&PlusMinus;\mathrm{\&theta;})\end{array}\right.\\ Z_i=Z_1+{\mathrm{\&Delta;Z}}_i=Z_1+\mathrm{\&theta;}\left(\frac{Z_2-Z_1}{\mathrm{\&alpha;}}\right)\end{array}\right.$

It is calculated each key point coordinate N_i(X_i,Y_i,Z_i), and each key point coordinate is substituted into formula 1), calculate Feed shaft or the actual arc track passed by of main shaft, more each key point actual coordinate value is substituted into formula 2), carry out segmentation excellent Change；

Depth optimization: gained is respectively optimized key point place value as initial value, substitution formula 1) and formula 2) in constraints | N_i” (X_i”,Y_i”,Z_i”)-N_i'(X_i',Y_i',Z_i')|≤ε₂Under be iterated calculating and realize depth optimization, wherein, ε₂Represent error threshold Value.

5. Digit Control Machine Tool synthetic error three rank Optimization Compensation method based on amendment NC program as claimed in claim 4, it is special Levy and be, after carrying out depth optimization, according to formula

$\left\{\begin{array}{c}{I}_i^{\&prime;}=X_o-X_{i-1}^{\&prime;}\\ J_i^{\&prime;}=Y_o-Y_{i-1}^{\&prime;}\end{array}\right.$

The center of circle is corrected, (I '_i, J '_i) represent the central coordinate of circle after correcting.

6. the Digit Control Machine Tool synthetic error three rank Optimization Compensation method based on amendment NC program as described in claim 4 or 5, its It is characterised by, for carrying out the some place value after depth optimization, also includes:

CalculateWork as Δ > ε₃Time, according to formula

${N_{i-1}}^{\&prime;\&prime;}({X_{i-1}}^{\&prime;\&prime;},{Y_{i-1}}^{\&prime;\&prime;},{Z_{i-1}}^{\&prime;\&prime;})=N_{i-1}(X_{i-1},Y_{i-1},Z_{i-1})+\frac{1}{2}\left(N_{i-1,p}^e\right(x_{i-1},y_{i-1},z_{i-1})-N_{i-1}(X_{i-1},Y_{i-1},Z_{i-1}\left)\right)$

Amended key point is further revised, wherein, ε₃Represent error threshold.

7. Digit Control Machine Tool synthetic error three rank Optimization Compensation method based on amendment NC program as claimed in claim 2, it is special Levy and be, if walking the motion comprising swinging axle in instruction in advance, then:

Between this section of track, insert point midway refine key point, point midway N as segmentation_1.5(X_1.5,Y_1.5,Z_1.5) coordinate Computational methods are:

$\left\{\begin{array}{c}{N}_i(X_i,Y_i,Z_i)=\frac{1}{2}\left(N_1\right(X_1,Y_1,Z_1)+N_2(X_2,Y_2,Z_2\left)\right)\\ N_i(A_i,B_i)=\frac{1}{2}\left(N_1\right(A_1,B_1)+N_2(A_2,B_2\left)\right)\end{array}\right.;$

Will a position N_1.5(X_1.5,Y_1.5,Z_1.5)、N_1.5(A_1.5,B_1.5) and N₂(X₂,Y₂,Z₂)、N₂(A₂,B₂) substitute into formula 1) and formula 2), it is achieved first suboptimization obtains a position N_i'(X_i',Y_i',Z_i') and N_i'(A_i',B_i')；

Will a position N_i'(X_i',Y_i',Z_i') and N_i'(A_i',B_i') substitute into formula 1) and formula 2), in constraintsUnder be iterated computing and realize depth optimization, obtain correction value N_i”(X_i”,Y_i”,Z_i”) With N_i”(A_i”,B_i"), wherein, ε₄Represent error threshold.