CN105045205A - Cutter position path generation method based on triangle mesh offset compensation and numerical control processing system thereof - Google Patents

Abstract

The invention provides a triangle mesh offset compensation method used for cutter position path generation. Offset distance compensation is carried out on a triangle mesh acquired through a vertex offset method again. The specific method comprises the steps that an angle between the current vertex and each adjacent patch normal vector is calculated; the effective offset compensation distance of each patch for the current vertex is calculated; the weight of each patch is calculated; the weight ratio of each patch is calculated; the offset compensation distance of the current vertex is calculated; and the offset distance is the sum of the radius of a ball head cutter and the offset compensation distance. The method automatically compensates the offset distance through calculation, and has the advantages of easy operation and reliable use. A CL path section plane method which carries out direct numerical control processing on a triangle mesh is supplemented and improved. The problem of processing overcut of direct triangle mesh numerical control processing is solved. The processing precision of direct triangle mesh model numerical control processing is improved.

Description

A kind of cutter spacing path generating method based on triangle gridding bias compensation and digital-control processing system thereof

Technical field

The present invention relates to a kind of cutter spacing path generating method based on triangle gridding bias compensation, also relate to the digital-control processing system utilizing the method, belong to the technical field of the digital control system in numerical control machine tool.

Background technology

Along with the development of computer technology and Digitized Manufacturing Technology, increasing physical part directly realizes numerical control programming and processing (triangle grid model by the triangle grid model of scanning, it is the expression-form that a kind of Surface tessellation be made up of a series of interconnective triangle surface in three dimensions approaches, because triangle gridding can reflect the pattern of actual curved surface complexity flexibly, therefore be applicable to the Scattered data points of Arbitrary distribution, it is utilized widely in technical fields such as surface reconstruction, curved surface segmentation and model fairing).The Direct numerical control technology of triangle grid model can expedite product performance history, enhances productivity and reduces costs.Wherein, CL path plane cutting method is one of current cutter path generating method based on triangle grid model, and its way is: be biased triangle grid model according to actual process tool.Wherein, the calculating of vertex normal vector will affect the effect of the biased of triangle grid model and following process.In the plane cutting method of CL path, the distance that triangle gridding is biased carries out selecting according to process tool, and for ball-end mill, offset or dish is the radius of ball-end mill, and for annular cutter, then needs to carry out secondary to triangle grid model and be biased.Be biased the biasing means based on summit and the biasing means based on tri patch to triangle gridding, wherein, the biasing means based on summit needs the vertex normal vector calculating triangle grid model.For the calculating of triangle gridding vertex normal vector, need to consider the tri patch information adjacent with this summit, its method is vowed and is weighted read group total.The CL path main operating process of plane cutting method comprises biased triangle grid model, and cutting plane asks for the cutter location on biased triangle gridding, carries out curve fitting to cutter location, the beeline approaching in matched curve, the generation of numerical control code.Wherein, the method be biased based on summit is conventional triangle gridding biasing means.The main thought of the method is that the method first calculating each summit of triangle gridding is vowed, then makes each summit along the biased ball-end mill radius of the vertex normal vector calculated, and the summit that finally connection is biased generates biased triangle grid model.

The method that summit is biased can calculate fast and effectively and obtain biased triangle grid model, but in fact the method can not ensure that the distance of triangle grid model and the former triangle grid model be biased is the ball-end mill radius of requirement, a schematic three-dimensional analysis is carried out below in conjunction with accompanying drawing 1, summit on square model, along direction of normal offset or dish, obtains the summit be biased.Connect each biased summit, generate biased square model.But get a little on biased square model face, can find that got point to the distance of former square model is be less than the R of requirement.Namely, under three-dimensional situation, the method that summit is biased cannot ensure the offset or dish of bias model.According to existing biasing means principle of operation as Figure 2-Figure 5, Fig. 2 is overall schematic diagram, and Fig. 3-Fig. 5 is the partial enlarged drawing in Fig. 2, is not difficult to find out from Fig. 3-Fig. 5, and number in the figure 6,7,8 is actual cutter location, and over-cutting can be caused in these three point of contacts.This can cause the processing over-cutting of actual digital control processing, and affects the machining precision of digital control processing.

Through retrieval, Chinese patent 200810159746.1 discloses one " triangular gridding subdivision curved surface NC tool track fast generation method ", the generation method of what although the method was very detailed disclose cutter rail, its generating algorithm can not avoid the generation of biased not in place and over-cutting.

Summary of the invention

Technical matters to be solved by this invention is, a kind of triangle gridding bias compensation methodology for cutter spacing coordinates measurement is provided, this bias compensation methodology ensure that the offset or dish of biased triangle grid model dough sheet meets the requirement of CL path plane cutting method, thus improve the machining precision of CL path plane cutting method, reduce digital control processing and cross the degree of cutting.

Technical matters to be solved by this invention is, a kind of triangle gridding bias compensation methodology for cutter spacing coordinates measurement is provided, this bias compensation methodology ensure that the offset or dish of biased triangle grid model dough sheet meets the requirement of CL path plane cutting method, thus improve the machining precision of CL path plane cutting method, reduce digital control processing and cross the degree of cutting.

The present invention solves the technical scheme of above technical matters:

Based on a cutter spacing path generating method for triangle gridding bias compensation, comprise the steps:

(1) triangle grid model is set up;

(2) carry out being biased to triangle grid model and obtain biased triangle grid model, wherein offset or dish is that ball-end mill radius is biased complementary range;

(3) based on described biased triangle grid model, cutter spacing information is obtained by the mode of curve;

(4) tool setting site information carries out code output, generates numerical control code and is used for digital control processing.

The summit biasing means of the present invention to triangle gridding is studied, analyze the problem of its offset or dish deficiency, in conjunction with the CL path plane cutting method of triangle gridding Direct numerical control, what have studied that triangle gridding offset or dish deficiency causes processedly cuts problem, propose the backoff algorithm for triangle gridding offset or dish, solve the processed of triangle gridding Direct numerical control and cut problem, improve the machining precision of triangle grid model Direct numerical control.The method is improved on the basis that triangle gridding summit is biased, effective offset or dish is calculated by summit adjacent triangular faces information, and compensate in the biased process of triangle gridding, thus be effectively biased triangle gridding, and then obtain effective numerical control machining code.

The technical scheme that the present invention limits further is:

Further, biased triangle grid model is determined as follows:

(1) obtain the data message of triangle gridding, extract the coordinate information on each summit and the data message of adjacent dough sheet;

(2) by the data message of the adjacent dough sheet in summit, the direction of normal on each summit of triangle gridding is calculated;

(3) bias compensation distance is calculated according to bias compensation methodology;

(4) according to calculating gained complementary range, double offset is carried out to each summit;

(5) after connecting all double offsets, the summit of gained generates revised triangle gridding.

Further, bias compensation distance obtains as follows:

(1) angle that current vertex and adjacent each dough sheet method are vowed is calculated;

(2) the effective bias compensation distance of each dough sheet for current vertex is calculated;

(3) weight of each dough sheet is calculated;

(4) weight proportion of each dough sheet is calculated;

(5) the bias compensation distance of current vertex is calculated.

Further, obtain cutter spacing information by the mode of curve to carry out as follows:

(1) cutting plane asks for the intersection point on described biased triangle grid model, and intersection point is the borderline point of tri patch;

(2) pair cross-section intersection point carries out curve fitting, and namely carries out the spline curve interpolation of intersection point;

(3) curve of beeline approaching matching, obtains the cutter location information in matched curve.

Further, in the step one that bias compensation distance calculates, the computing formula of angle is:

${\mathrm{\θ}}_{i,j}=arccos\frac{{\stackrel{\→}{N}}_{i,j}\·{\stackrel{\→}{V}}_{pi}}{\left|{\stackrel{\→}{N}}_{i,j}\right|\·\left|{\stackrel{\→}{V}}_{pi}\right|},$

Wherein: θ _i,jfor summit p _iwith adjacent triangular faces F _jangle, for summit p _iadjacent triangular faces F _jmethod vow, for summit p _imethod vow;

Further, in the step 2 that bias compensation distance calculates, effective bias compensation distance is:

Δ _i,j＝L _i,j-R＝L _i,j(1-cosθ _i,j)，

Wherein: Δ _i,jfor adjacent dough sheet F _jcompensation offset or dish, L _i,jfor total distance that actual needs is biased, R is the radius of ball-end mill;

Further, in the step 3 that bias compensation distance calculates, the computing formula of weight is:

Wherein: extremely for summit p _iadjacent triangular faces F ₁to F _nmethod vow, W _{i, 1}to W _i,nfor summit p _iadjacent triangular faces F ₁to F _nweight;

Further, in the step 4 that bias compensation distance calculates, the computing formula of weight proportion is:

$W_{i,j}^{\′}=\frac{w_{i,j}}{{\mathrm{\Σ}}_{j=1}^n{w}_{i,j}},$

Wherein: W _i,jfor step 3 kind calculates the weight of gained, W ' _i,jfor weight proportion;

Further, in the step 5 that bias compensation distance calculates, the computing formula of bias compensation distance is:

${\mathrm{\Δ}}_i=\underset{i=1}{\overset{n}{\Σ}}{W}_{i,j}^{\′}\·{\mathrm{\Δ}}_{i,j}$

Wherein: Δ _ifor bias compensation distance, W ' _i,jfor the weight proportion calculated in step 4, Δ _i,jfor adjacent dough sheet F _jcompensation offset or dish.

Based on a digital-control processing system for triangle gridding bias compensation, comprising:

Triangle grid model generation module, for generating triangle grid model;

Biased triangle grid model generation module, for carrying out being biased to triangle grid model and obtaining biased triangle grid model, wherein offset or dish is that ball-end mill radius is biased complementary range;

Fitting module, for based on described biased triangle grid model, obtains cutter spacing information by the mode of curve;

Numerical control code generation module, carries out code output for tool setting site information, generates numerical control code and is used for carrying out digital control processing.

The present invention compared with prior art, have the following advantages and high-lighting effect: simple to operate, use reliable, by computing auto-compensation offset or dish, the CL path plane cutting method of triangle gridding Direct numerical control is supplemented and improved, solve the processed of triangle gridding Direct numerical control and cut problem, improve the machining precision of triangle grid model Direct numerical control.

Accompanying drawing explanation

Fig. 1 is schematic three-dimensional analysis chart in background technology;

Fig. 2 is the present invention and prior art comparison diagram;

Fig. 3 is the partial enlarged drawing of in Fig. 23;

Fig. 4 is the partial enlarged drawing of in Fig. 24;

Fig. 5 is the partial enlarged drawing of in Fig. 25;

Fig. 6 is use schematic flow sheet of the present invention;

Fig. 7 is the idiographic flow schematic diagram of compensation method;

Fig. 8 is in compensation method, the angle calcu-lation three-dimensional graph of convex surface;

Fig. 9 is that the method on summit in Fig. 8 is vowed and the cross section that the method for adjacent dough sheet is vowed;

Figure 10 is in compensation method, the angle calcu-lation three-dimensional graph of concave surface;

Figure 11 is that the method on summit in Figure 10 is vowed and the cross section that the method for adjacent dough sheet is vowed;

In figure: 1, triangle grid model; 2, the triangle grid model that summit is biased; 3, partial enlarged drawing; 4, partial enlarged drawing; 5, partial enlarged drawing; 6, actual cutter location; 7, actual cutter location; 8, actual cutter location; 9, correct cutter location; 10, correct cutter location; 11: correct cutter location; 12, ball-end mill; 13, actual ball-end mill position; 14, correct ball-end mill position; 15, excessively region is cut.

Embodiment

Embodiment 1

Entire flow of the present invention as shown in Figure 6, its complete triangle gridding process of establishing is as follows: (1) set up triangle grid model (2) carry out being biased according to summit biasing means to triangle grid model and obtain biased after triangle grid model, wherein offset or dish is ball-end mill radius; (3) obtain the data message of triangle gridding, the data message of triangle grid model is reconstructed, extracts the coordinate information on each summit and the data message of adjacent dough sheet; (4) by the data message of the adjacent dough sheet in summit, the direction of normal on each summit of triangle gridding is calculated; (5) bias compensation distance is calculated according to bias compensation methodology; (6) according to calculating gained complementary range, double offset is carried out to each summit; (7) after connecting all double offsets, the summit of gained generates revised triangle gridding (8) cutting plane and asks for the intersection point revised on Vee formation grid model, and intersection point is the borderline point of tri patch; (9) pair cross-section intersection point carries out curve fitting, and namely carries out the spline curve interpolation of intersection point; (10) curve of beeline approaching matching, obtains the cutter location information in matched curve; (11) tool setting site information carries out code output, generates numerical control code.The numerical control code of final generation directly can input numerically-controlled machine, and carries out digital control processing.

Compensation method concrete grammar is: the angle that (1) calculating current vertex and adjacent each dough sheet method are vowed; (2) the effective bias compensation distance of each dough sheet for current vertex is calculated; (3) weight of each dough sheet is calculated; (4) weight proportion of each dough sheet is calculated; (5) the bias compensation distance of current vertex is calculated; (6) offset or dish is ball-end mill radius and bias compensation distance sum.

In compensation method:

Step one, the computing formula of angle is:

${\mathrm{\θ}}_{i,j}=arccos\frac{{\stackrel{\→}{N}}_{i,j}\·{\stackrel{\→}{V}}_{pi}}{\left|{\stackrel{\→}{N}}_{i,j}\right|\·\left|{\stackrel{\→}{V}}_{pi}\right|},$

Wherein: θ _i,jfor summit p _iwith adjacent triangular faces F _jangle, for summit p _iadjacent triangular faces F _jmethod vow, for summit p _imethod vow.

Step 2, effective bias compensation distance is:

Δ _i,j＝L _i,j-R＝L _i,j(1-cosθ _i,j)，

Wherein: Δ _i,jfor adjacent dough sheet F _jcompensation offset or dish, L _i,jfor total distance that actual needs is biased, R is the radius of ball-end mill.

Step 3, the computing formula of weight is:

Wherein: extremely for summit p _iadjacent triangular faces F ₁to F _nmethod vow, W _{i, 1}to W _i,nfor summit p _iadjacent triangular faces F ₁to F _nweight.

Step 4, the computing formula of weight proportion is:

$W_{i,j}^{\′}=\frac{w_{i,j}}{{\mathrm{\Σ}}_{j=1}^n{w}_{i,j}},$

Wherein: W _i,jfor step 3 kind calculates the weight of gained, W ' _i,jfor weight proportion.

Step 5, the computing formula of bias compensation distance is:

${\mathrm{\Δ}}_i=\underset{i=1}{\overset{n}{\Σ}}{W}_{i,j}^{\′}\·{\mathrm{\Δ}}_{i,j}$

Wherein: Δ _ifor bias compensation distance, W ' _i,jfor the weight proportion calculated in step 4, Δ _i,jfor adjacent dough sheet F _jcompensation offset or dish.

Adopt compensation method provided by the invention, as Figure 2-Figure 5, correct cutter location can be obtained during cutter work, fundamentally can avoid the generation of digital control processing over-cutting like this, simultaneously because the method is the supplementary and improvement carried out the existing truncated figure in CL path, so its practice and extension is very easy to, use also very reliable.

In addition to the implementation, the present invention can also have other embodiments.All employings are equal to the technical scheme of replacement or equivalent transformation formation, all drop on the protection domain of application claims.

Claims (10)

1., based on a cutter spacing path generating method for triangle gridding bias compensation, it is characterized in that: comprise the steps:

(1) triangle grid model is set up;

(2) carry out being biased to triangle grid model and obtain biased triangle grid model, wherein offset or dish is that ball-end mill radius is biased complementary range;

(3) based on described biased triangle grid model, cutter spacing information is obtained by the mode of curve;

(4) tool setting site information carries out code output, generates numerical control code and is used for digital control processing.

2. cutter spacing path generating method according to claim 1, is characterized in that: described biased triangle grid model is determined as follows:

(1) obtain the data message of triangle gridding, extract the coordinate information on each summit and the data message of adjacent dough sheet;

(2) by the data message of the adjacent dough sheet in summit, the direction of normal on each summit of triangle gridding is calculated;

(3) bias compensation distance is calculated according to bias compensation methodology;

(4) according to calculating gained complementary range, double offset is carried out to each summit;

(5) after connecting all double offsets, the summit of gained generates revised triangle gridding.

3. cutter spacing path generating method according to claim 1 and 2, is characterized in that: described bias compensation distance obtains as follows:

(1) angle that current vertex and adjacent each dough sheet method are vowed is calculated;

(2) the effective bias compensation distance of each dough sheet for current vertex is calculated;

(3) weight of each dough sheet is calculated;

(4) weight proportion of each dough sheet is calculated;

(5) the bias compensation distance of current vertex is calculated.

4. cutter spacing path generating method according to claim 1, is characterized in that: obtain cutter spacing information by the mode of curve and carry out as follows:

(1) cutting plane asks for the intersection point on described biased triangle grid model, and intersection point is the borderline point of tri patch;

(2) pair cross-section intersection point carries out curve fitting, and namely carries out the spline curve interpolation of intersection point;

(3) curve of beeline approaching matching, obtains the cutter location information in matched curve.

5. cutter spacing path generating method according to claim 3, is characterized in that: in step one, and the computing formula of angle is:

${\mathrm{\θ}}_{i,j}=arccos\frac{{\stackrel{\→}{N}}_{i,j}\·{\stackrel{\→}{V}}_{pi}}{\left|{\stackrel{\→}{N}}_{i,j}\right|\·\left|{\stackrel{\→}{V}}_{pi}\right|},$

Wherein: θ _{i, j}for summit p _iwith adjacent triangular faces F _jangle, for summit p _iadjacent triangular faces F _jmethod vow, for summit p _imethod vow.

6. cutter spacing path generating method according to claim 3, is characterized in that: in step 2, and effective bias compensation distance is:

Δ _i，j＝L _i，j-R＝L _i，j(1-cosθ _i，j)，

Wherein: Δ _{i, j}for adjacent dough sheet F _jcompensation offset or dish, L _{i, j}for total distance that actual needs is biased, R is the radius of ball-end mill.

7. cutter spacing path generating method according to claim 3, is characterized in that: in step 3, and the computing formula of weight is:

Wherein: extremely for summit p _iadjacent triangular faces F ₁to F _nmethod vow, w _{i, 1}to w _{i, n}for summit p _iadjacent triangular faces F ₁to F _nweight.

8. cutter spacing path generating method according to claim 3, is characterized in that: in step 4, and the computing formula of weight proportion is:

$W_{i,j}^{\′}=\frac{W_{i,j}}{{\mathrm{\Σ}}_{j=1}^n{W}_{i,j}},$

Wherein: w _{i, j}for step 3 kind calculates the weight of gained, w ' _{i, j}for weight proportion.

9. cutter spacing path generating method according to claim 3, is characterized in that: in step 5, and the computing formula of bias compensation distance is:

${\mathrm{\Δ}}_i=\underset{i=1}{\overset{n}{\Σ}}{W}_{i,j}^{\′}\·{\mathrm{\Δ}}_{i,j}$

Wherein: Δ _ifor bias compensation distance, w ' _{i, j}for the weight proportion calculated in step 4, Δ _{i, j}for adjacent dough sheet F _jcompensation offset or dish.

10. based on a digital-control processing system for triangle gridding bias compensation, it is characterized in that, comprising:

Triangle grid model generation module, for generating triangle grid model;

Biased triangle grid model generation module, for carrying out being biased to triangle grid model and obtaining biased triangle grid model, wherein offset or dish is that ball-end mill radius is biased complementary range;

Fitting module, for based on described biased triangle grid model, obtains cutter spacing information by the mode of curve;

Numerical control code generation module, carries out code output for tool setting site information, generates numerical control code and is used for carrying out digital control processing.