CN101510086B - Multi-shaft numerical control machining knife rail generating method for product triangle grid model - Google Patents

Abstract

The invention provides a multi-axis numerical control machining tool path generation method for the triangular mesh model of a product, and is characterized in that: a R*S-tree dynamic space index structure organization triangle patch topological neighbor relationship is adopted; based on the structure, the intersection is carried out to the tool-path cross-section and the triangular mesh model for obtaining a cross-section data point; according to an area averaging method, the vector of the corresponding cross-section data point is calculated; the instantaneous processing area corresponding to each cross-section data point is inquired; according to the tangent relationship between the tool and the surface, edge, and vertex of each triangle in the instantaneous processing area, a tool path calculation method of surface tangency, edge tangebcy or vertex tangency is adopted for obtaining corresponding cutting points; a minimum tree generation method is adopted for arranging the cutting points in sequence; and a multi-axis numerical control machining tool path is generated. The method is suitable for the generation of the multi-axis numerical control machining tool path of various complex triangular mesh models, and has high algorithm running efficiency.

Description

The multi-shaft numerical control machining knife rail generating method of product triangle grid model

Technical field

The invention provides a kind of multi-shaft numerical control machining knife rail generating method of product triangle grid model, belong to the Computer-aided manufacturing field.

Background technology

In the product reverse-engineering, adopt equipment such as laser scanner to obtain the scattered point cloud data of product entity model surface usually, and these data are carried out triangulation generate triangle grid model, approach former solid model.Directly generate numerical control machining knife rail based on triangle grid model, can avoid the process of reconstruction of products C AD model and the cumulative errors of Model Reconstruction, thereby effectively improve product development efficiency and machining precision based on reverse-engineering.

The prior art literature search is found, Sun Yuwen etc. are at academic journal " mechanical engineering journal " 2002,38 (10): in the scientific paper of delivering on the P50-53 " based on the cutter spacing track computing method of triangular gridding curve model ", by creating the tri patch adjacency list, search the tri patch that intersects with cutter rail cutting plane, vow the intersection point calculation cutter location of interpolation boundary curve and cutter rail cutting plane according to the grid vertex method, higher based on the cutter rail precision that this method generates, but tri patch is too loaded down with trivial details in abutting connection with the foundation and the maintenance process of chained list, there is a large amount of dough sheet redundant informations in the chained list, have a strong impact on the formation speed of numerical control machining knife rail, and this method can not effectively be avoided cutter rail interference problem.Gao Hongwei etc. are at academic journal " Engineering Drawing journal " 2005; 26 (3): in the scientific paper of delivering on the P168-172 " three processing do not have the accelerating algorithm of interfering cutter path based on the Zmap grid "; be triangle grid model structure cutter spacing face and protective surface; ask friendship by the vertical curve of Zmap mesh node and the cutter spacing face and the protective surface of triangular plate; get the maximum intersection point of z value as cutter location; can effectively handle the nothing that is suitable for various cutters interferes the cutter rail to generate; but this method is required to be the summit in the numerical control machining knife rail generative process; the limit increases sphere; the face of cylinder is as protective surface; its algorithm complexity and calculated amount are big, and this algorithm only is applicable to the generation of three-axis numerical control processing cutter rail.Zhu Hu etc. are at academic journal " Liaoning Project Technology University's journal " 2007,26 (2): in the scientific paper of delivering on the P273-275 " the STL model cutter path based on the summit biasing generates ", the normal vector of each tri patch that utilization links to each other with the summit, calculate the bias point on each summit, and by the complete bias model of forming by tri patch of these bias point structures; With parallel cut bias model is cut into slices, in two-dimensional space, gained intersection section is carried out cutting and connection processing to generate numerical control machining knife rail, the formation speed of the cutter rail that when avoiding interfering, effectively improves, but this method can only be applicable to three machining locus of ball end mill.

In sum, existing triangle grid model numerical control machining knife rail generating method can not be directly used in multi-shaft numerical control machining knife rail and generate, therefore, generate multi-shaft numerical control machining knife rail fast based on triangle grid model and become the technical matters that those skilled in the art need to be resolved hurrily.

Summary of the invention

The object of the present invention is to provide a kind of multi-shaft numerical control machining knife rail generating method of product triangle grid model, and this method is applicable to that the numerical control machining knife rail of tack slotting cutter, ball end mill and three kinds of cutters of annulus slotting cutter generates.Its technical scheme is:

A kind of multi-shaft numerical control machining knife rail generating method of product triangle grid model is characterized in that steps in sequence is: 1) improve R ^*-tree obtains being suitable for the dynamic space index structure R of storage products triangle grid model ^*The S-tree is improved R ^*-tree dynamic space index data structure obtains R ^*The method of S-tree is specifically: be expressed as four-dimensional some object (x, y, z, r with tri patch and index node MBR are unified ₁), x wherein, y, z are the MBR centre coordinate, r ₁Be MBR circumsphere radius value,, make up product triangle grid model dynamic space index structure, based on R by the cluster sub-clustering of tri patch set ^*The S-tree is set up the dynamic space index structure of product triangle grid model, and wherein MBR represents minimum area-encasing rectangle; 2) based on triangle grid model dynamic space index structure, tool setting rail cutting plane and triangle grid model are asked friendship, obtain the cross-section data point, its acquisition methods is specifically: by the position relation of cutter rail cutting plane and each layer of triangle grid model space index structure node, successively search each the layer index node that intersects with cutter rail cutting plane, extract the data node that intersects with cutter rail cutting plane, each limit of extracting data inter-node tri patch and cutter rail cutting plane asked hand over and overlapping point that deletion is asked in the intersection point obtains the cross-section data point, with the intersection point that obtains as the cross-section data point; 3) based on triangle grid model dynamic space index structure, regional neighbour's tri patch of inquiry cross-section data point, the method that adopts the area averaging method to calculate the respective cross-section data point vows, its computing method specifically: employing R ^*S-tree range query algorithm is searched fast apart from the tri patch of cross-section data point less than ζ, the product that each tri patch area and its per unit system the are vowed summation that adds up, the method that the gained result asks for corresponding cross-section data point divided by the area sum of each tri patch is vowed that wherein ζ represents the coverage threshold value; 4) vow according to cross-section data point and method thereof and determine tool axis that based on triangle grid model dynamic space index structure, inquiry is apart from the tri patch set of tool axis less than tool radius, with it as instantaneous machining area; 5) according to the position orientation relation between each tri patch in cutter and the instantaneous machining area, employing face is tangent, tangent or the tangent cutter Location Calculation Method in summit in limit is obtained corresponding cutter location, and in the cutter location that obtains, be taken at the highest cutter location in position on the cutter axis orientation as the corresponding cutter location of current cross-section data point, its method is specifically: each cross-section data is put each tri patch in the corresponding instantaneous machining area, at first adopt the face tangent method to calculate cutter location, if the cutter location that is obtained is effective, then with the cutter location of this cutter location as this tri patch correspondence, otherwise three limits of tri patch and three summits are carried out respectively the tangent cutter spacing in limit is calculated and the tangent cutter spacing in summit is calculated, in the effective cutter location that obtains, be taken at the cutter location of the highest cutter location in position on the cutter axis orientation as this tri patch correspondence, relatively the height of the corresponding cutter location of each tri patch on cutter axis orientation is taken at cutter location the highest on the cutter axis orientation as the corresponding cutter location of current cross-section data point; 6) adopt the cutter location of minimum spanning tree method pair cross-section data point correspondence to sort, generate the multi-shaft numerical control machining knife rail of triangle grid model.

The multi-shaft numerical control machining knife rail generating method of described product triangle grid model, in the tangent cutter location computing method of step 5) face, ball end mill, tack slotting cutter and the unification of annulus slotting cutter are the annulus slotting cutter, vow the property calculation cutter location vertical according to cutter-contact point place tool surface method with tri patch, specifically: establishing current tri patch is T, unified tack slotting cutter, ball end mill are the annulus slotting cutter, tool radius is R, radius of corner is r, v is the vector of unit length of cutter shaft A, n is that the per unit system of tri patch T is vowed P _cFor the points of tangency on cutter and plane, T place is a cutter-contact point, P ₀Be the intersection point on A and plane, T place, P _sBe the cutter location of tri patch T correspondence, v _rBe P _sPoint to P _cThe vector in the corresponding fillet center of circle, by formula (1):

$\left\{\begin{array}{c}{v}_r=(R-r)\frac{v\×(v\×n)}{|v\×(v\×n)|}\\ (\mathrm{tv}+v_r-\mathrm{rn})\·n=0\end{array}\right.---\left(1\right),$

Get P _sWith P ₀Between apart from t, in conjunction with P ₀, v, v _r, n tries to achieve P _s, P _c, judge P _cWhether in T inside, if at T inside, then P _sEffectively, otherwise P _sIt is invalid,

The multi-shaft numerical control machining knife rail generating method of described product triangle grid model, in the tangent cutter location computing method in step 5) limit, for ball end mill or tack slotting cutter, vow the property calculation cutter location vertical according to cutter-contact point place tool surface method with place, limit straight line, adopt the iteration Method cutter location extract the effective range on limit for the annulus slotting cutter after, specifically be for ball end mill or tack slotting cutter: establish when the front be E, R is tack slotting cutter or ball end mill radius, A is a tool axis, v is the vector of unit length of A, L is the straight line at E place, limit, and n is the vector of unit length of L, P ₀, P ₁Be respectively A and E and go up 2 nearest points, P _sBe cutter location, P _cBe cutter-contact point, f is by P ₁And vector

The plane of determining, P _tBe P _sSubpoint on f, v _cFor by P _cPoint to P _tVector, v _tBe the vector of f perpendicular to L, by formula (2):

$\left\{\begin{array}{c}{v}_t=\frac{n\×(v\×n)}{|n\×(v\×n)|}\\ (\mathrm{tv}-v_c)\·v_t=0\end{array}\right.---\left(2\right),$

Ask for P _sWith P ₀Apart from t, with its substitution formula (3):

$\left\{\begin{array}{c}{P}_s={\mathrm{<figure-callout\; id="0"\; label="P"\; filenames="H2009100202017E00022.png"\; state="\{\{state\}\}">P</figure-callout>}}_0+\mathrm{tv}\\ P_c=P_s+\stackrel{\&OverBar;}{P_0{\mathrm{<figure-callout\; id="1"\; label="P"\; filenames="H2009100202017E00021.png,H2009100202017E00082.png"\; state="\{\{state\}\}">P</figure-callout>}}_1}-v_c\end{array}\right.---\left(3\right),$

Calculate P _s, P _c, judge P _cWhether in E inside, as P then in E inside _sEffectively; For the annulus slotting cutter, look in the other direction along tool axis, the part that is covered by cutter is the effective range that needs iterative computation in the tangent cutter location computation process in limit, obtain after the effective range its effective line segment when calculating cutter location, effectively evenly getting the individual point of 2n+1 (n＞1) on the line segment, each point is carried out the tangent cutter spacing in summit calculate, iterative obtains final cutter location, and concrete steps are as follows: 1. effectively evenly getting individual some P of 2n+1 (n＞1) on the line segment _i(i=0,1 ..., 2n); 2. each point is carried out the tangent cutter spacing in summit and calculate, obtain corresponding cutter location Q _i(i=0,1 ..., 2n); 3. more corresponding cutter location Q _i(i=0,1 ..., the 2n) height on the tool axis direction obtains the highest cutter location Q _jWith minimum cutter location Q _k, if j=0 or j=2n, then the highest cutter location Q _jBe the cutter location of asking, cutter location calculates and finishes, otherwise carries out 4.; 4. calculate the highest cutter location Q _jWith minimum cutter location Q _kBetween apart from d, if apart from d less than the deviation threshold of setting, the highest cutter location Q _jBe the cutter location of asking, EOP (end of program), otherwise with P _J-1P _J+1For 1. effective line segment returns step.

The multi-shaft numerical control machining knife rail generating method of described product triangle grid model, in the tangent cutter location computing method in step 5) summit, ball end mill, tack slotting cutter and the unification of annulus slotting cutter are the annulus slotting cutter, calculate cutter location according to the relation of the position between cutter-contact point and the tool axis, specifically: establishing R is tool radius, and r is the cutter radius of corner, and v is the vector of unit length of cutter shaft A, point P ' is the projection of P on A, and l is cutter-contact point P _cTo the distance of A, by formula (4):

$\left\{\begin{array}{cc}{P}_s=P^{\&prime;}+\mathrm{rv}& (l\&le;R-r)\\ P_s=P^{\&prime;}+\sqrt{r^2-{(l-R+r)}^{2}v}& (R-r<l\&le;R)\end{array}\right.---\left(4\right),$

Try to achieve effective cutter location P _s

The present invention compared with prior art has following three advantages:

(1) adopts R ^*The S-tree is set up triangle grid model dynamic space index structure, realizes the inquiry of regional neighbour's data fast and accurately, has effectively improved the cutter rail formation efficiency of triangle grid model;

(2) by regional neighbour's tri patch of inquiry cross-section data point, the method that adopts the area averaging method to calculate the respective cross-section data point is vowed and is determined tool axis, realized the generation of product triangle grid model multi-shaft numerical control machining knife rail;

(3) tangent by face, the limit is tangent or the tangent mode in summit is carried out cutter spacing and calculated, and has effectively avoided the cutter spacing interference problem of tack slotting cutter, ball end mill and annulus slotting cutter, improved the cutter rail and generated quality.

Description of drawings

Fig. 1 is a program flow diagram of the present invention;

Fig. 2 is that intermediate cam grid model dynamic space index structure of the present invention makes up synoptic diagram;

Fig. 3 is people's face portion's triangle grid model and each layer of dynamic space index structure node MBR design sketch thereof in the embodiment of the invention;

Fig. 4 is numerical control machining knife rail product process figure of the present invention;

Fig. 5 is a cutter rail cutting plane data point set acquisition process synoptic diagram in the embodiment of the invention;

Fig. 6 is that the present invention calculates cross-section data point method arrow synoptic diagram according to tri patch normal vector and area;

Fig. 7 is the process flow diagram that cutter location of the present invention calculates;

Fig. 8 is that the tangent cutter spacing of face is calculated synoptic diagram among the present invention;

Fig. 9 is that the tangent cutter spacing of tack slotting cutter and ball end mill limit is calculated synoptic diagram among the present invention;

Figure 10 determines in the cutter scope the effectively synoptic diagram of line segment when adopting the tangent cutter spacing in limit to calculate at the annulus slotting cutter among the present invention;

Figure 11 is that the tangent cutter spacing in summit is calculated synoptic diagram among the present invention;

Figure 12 is that cutter spacing track and the method thereof that people's face portion triangle grid model is generated in the embodiment of the invention vowed partial enlarged drawing.

Embodiment

The invention will be further described below in conjunction with drawings and Examples:

Fig. 1 the present invention is based on the program flow diagram that triangle grid model generates multi-shaft numerical control machining knife rail fast.Data entry program 1 is responsible for reading in the triangle grid model data file, and creates the linear linked list storage organization for it.Triangle grid model dynamic space index structure construction procedures 2 adopts nested MBR that the triangle grid model data are carried out the dynamic space cluster and divides, for the data linear linked list that data entry program 1 is generated is set up upper strata R ^*S-tree space index structure.Numerical control machining knife rail calculation procedure 3 is by depth-first traversal triangle grid model dynamic space index structure, obtaining cross-section data point and method thereof fast vows, vow the instantaneous position of determining cutter shaft according to cross-section data point and method thereof, inquire about the instantaneous machining area of each cross-section data point, face according to each tri patch in cutter and the instantaneous machining area, the limit, the tangent relation on summit adopts face tangent, tangent or the tangent cutter Location Calculation Method in summit in limit is calculated the cutter location of each tri patch correspondence, compare the height of the corresponding cutter location of each tri patch on cutter axis orientation, be taken at the highest cutter location in position on the cutter axis orientation as the corresponding cutter location of current cross-section data point, adopt the minimum spanning tree method that each cross-section data is put corresponding cutter location and sort, realize the generation of triangle grid model multi-shaft numerical control machining knife rail.

Fig. 2 is the set of 13 tri patchs a), Fig. 2 b) for based on node MBR synoptic diagram in the constructed index structure of this set (wherein the child node of index node counts that higher limit is 8, lower limit is 3), Fig. 2 c) is the structural representation of index structure, node A is a root node, B, C are leaf node, and D, E, F, G, H, I, J, K, L, M, N, O, P, Q are the data node.

Embodiment: to Fig. 3 a) let others have a look at face portion triangle grid model generate five-shaft numerical control processing cutter rail.

Fig. 3 is embodiment people's face portion triangle grid model a), tri patch quantity is 7851, when making up its dynamic space index structure, indexing parameter is m=8, M=20, inserts nodal point number R=6 again, and the time that makes up this model dynamic space index knot is about 0.215364 second, Fig. 3 b) is dynamic space index structure root node MBR, Fig. 3 c) be second layer node MBR, Fig. 3 d) be three-layered node point MBR, Fig. 3 e) be leaf node MBR..

Fig. 4 is the process flow diagram of numerical control machining knife rail calculation procedure 3 among the present invention.The program of obtaining 4 that cutter rail cutting plane data point and method thereof are vowed, successively judge and the position of each layer of triangle grid model space index structure node relation for the current cutter rail cutting plane that reads, rapid extraction goes out the data node that intersects with cutter rail cutting plane, each limit of extracting data inter-node tri patch and cutter rail cutting plane asked hand over and overlapping point that deletion is asked in the intersection point obtains the cross-section data point, with the cross-section data point is impact point, inquire about its regional neighbour's tri patch, the method arrow of corresponding cross-section data point is asked for the gained result in the product that each tri patch area and its per unit system the are vowed summation that adds up divided by the area sum of each tri patch; Cutter location calculation procedure 5, vow the instantaneous position of determining tool axis according to cross-section data point and method thereof, depth-first traversal triangle grid model index structure obtains and the distance of the P tri patch smaller or equal to tool radius, according to cutter inquire in the face of each tri patch, the limit, the tangent relation on summit adopts face tangent, tangent or the tangent cutter Location Calculation Method in summit in limit is calculated the cutter location of each tri patch correspondence, the height of the corresponding cutter location of each tri patch on cutter axis orientation relatively is taken at the cutter location of the highest cutter location in position on the cutter axis orientation as current cross-section data point correspondence; Adopt the minimum spanning tree method that cutter location is sorted by cutter location sequencer program 6 at last and realize the generation of single file cutter rail.

Fig. 5 is the synoptic diagram of cutter rail cutting plane data point acquisition process among the present invention.Be v if cutter rail cutting plane method is vowed, the summit of index node is v _i(1≤i≤8), q is arbitrfary point on the cutter rail cutting plane, according to formula ε _i=v (q-v _i) (1≤i≤8) gained ε _iEach summit of symbol decision index node MBR of value and the position of cutter rail cutting plane relation, and then the position of judging index node and cutter rail cutting plane concerns, judge position relation with cutter rail cutting plane intersection data inter-node tri patch and cutter rail cutting plane, extract each tri patch that intersects with cutter rail cutting plane, each limit of tri patch and the cutter rail cutting plane that extract are asked friendship, obtain the cross-section data point, Fig. 5 a), Fig. 5 b) is respectively ground floor and the second layer index node that intersects with cutter rail cutting plane, Fig. 5 c) is the data node that intersects with cutter rail cutting plane, Fig. 5 d) be the tri patch that intersects with cutter rail cutting plane, Fig. 5 e) be the cross-section data point that obtains.

If current cross-section data point is P, the center of index node and its circumsphere radius are respectively c, r ₁, according to formula d=| (P-C) n|-r ₁Calculate the distance between cutter rail cutting plane data point and the index node, depth-first triangle grid model index structure obtains and the distance of the P data node less than ζ (coverage threshold value), calculate the distance of each data inter-node tri patch and P, extract from the distance of P tri patch smaller or equal to ζ, the tri patch of Ti Quing is total m as shown in Figure 6, calculates the wherein method arrow n of each tri patch _kWith area s _k(1≤k≤m), calculate the pairing cross-section data point of P according to formula (5).

$n=\underset{k=1}{\overset{m}{\mathrm{\&Sigma;}}}{s}_k{n}_k/\underset{k=1}{\overset{m}{\mathrm{\&Sigma;}}}{s}_k---\left(5\right)$

Fig. 7 is the process flow diagram of cutter location calculation procedure 5 of the present invention.For current cross-section data point is P, and its method vows that to n can determine instantaneous tool axis A by P, n, center and the circumsphere radius of triangle grid model index node MBR are respectively C, r ₁, then the distance of index node and A can be by formula d=| (C-P) * n|-r ₁Try to achieve.Adopt the depth-first traversal method to obtain fast and the distance of A data node set less than tool radius R, calculate in this set each tri patch to the distance of A, will be apart from the instantaneous machining area of the zone of forming less than the tri patch of R as cutter, the cutter location computing method tangent by face, that the limit is tangent or the summit is tangent are calculated the cutter location of each tri patch correspondence, compare the height of the corresponding cutter location of each tri patch on cutter axis orientation, fetch bit is put the highest cutter location as the corresponding cutter location of current cross-section data point.

Fig. 8 calculates synoptic diagram for the tangent cutter location of face among the present invention.Current tri patch is T, and unified tack slotting cutter, ball end mill are the annulus slotting cutter, and tool radius is that its value of R is 4, and radius of corner is r, and its value is 2, and v is the vector of unit length of cutter shaft A, and n is that the per unit system of tri patch T is vowed P _cFor the points of tangency on cutter and plane, T place is a cutter-contact point, P ₀Be the intersection point on A and plane, T place, P _sBe the cutter location of tri patch T correspondence, v _rBe P _sPoint to P _cThe vector in the corresponding fillet center of circle is asked for P by formula (6) _sWith P ₀Between apart from t, in conjunction with P ₀, v, v _r, n tries to achieve P _s, P _c, judge P _cWhether in T inside, if at T inside, then P _sEffectively, otherwise P _sInvalid.

$\left\{\begin{array}{c}{v}_r=(4-2)\frac{v\&times;(v\&times;n)}{|v\&times;(v\&times;n)|}\\ (\mathrm{tv}+v_r-\mathrm{rn})\&CenterDot;n=0\end{array}\right.---\left(6\right)$

Fig. 9 calculates synoptic diagram for the tangent cutter location of tack slotting cutter among the present invention and ball end mill limit.When the front is E, R is tack slotting cutter or ball end mill radius, and its value is 4, and A is a tool axis, and v is the vector of unit length of A, and L is the straight line at E place, limit, and n is the vector of unit length of L, P ₀, P ₁Be respectively A and E and go up 2 nearest points, P _sBe cutter location, P _cBe cutter-contact point, f is by P ₁And vector

The plane that (method as f is vowed) determined, P _tBe P _sSubpoint on f, v _cFor by P _cPoint to P _tVector, v _tBe the vector of f, ask for P by formula (7) perpendicular to L _sWith P ₀Apart from t, its substitution formula (8) is calculated P _s, P _c, judge P _cWhether in E inside, as P then in E inside _sEffectively.

$\left\{\begin{array}{c}{v}_t=\frac{n\&times;(v\&times;n)}{|n\&times;(v\&times;n)|}\\ (\mathrm{tv}-v_c)\&CenterDot;v_t=0\end{array}\right.---\left(7\right)$

$\left\{\begin{array}{c}{P}_s={\mathrm{<figure-callout\; id="0"\; label="P"\; filenames="H2009100202017E00022.png"\; state="\{\{state\}\}">P</figure-callout>}}_0+\mathrm{tv}\\ P_c=P_s+\stackrel{\&OverBar;}{P_0{\mathrm{<figure-callout\; id="1"\; label="P"\; filenames="H2009100202017E00021.png,H2009100202017E00082.png"\; state="\{\{state\}\}">P</figure-callout>}}_1}-v_c\end{array}\right.---\left(8\right)$

Figure 10 is the active line scope synoptic diagram on limit in the tangent cutter location calculating of annulus vertical milling knife-edge among the present invention.For looking in the other direction along tool axis as front E, the part that is covered by cutter is the effective range (solid line part) that needs iterative computation in the tangent cutter location computation process in limit, Figure 10 a) for center section effectively, Figure 10 b) be an end effectively, Figure 10 c) for all effectively, Figure 10 d) for when the front invalid.Obtain after the effective range its effective line segment when calculating cutter location, effectively evenly getting the individual point of 2n+1 (n＞1) on the line segment, each point is carried out the tangent cutter spacing in summit calculate, iterative obtains final cutter location, and concrete steps are as follows: 1. effectively evenly getting individual some P of 2n+1 (n＞1) on the line segment _i(i=0,1 ..., 2n); 2. each point is carried out the tangent cutter spacing in summit and calculate, obtain corresponding cutter location Q _i(i=0,1 ..., 2n); 3. more corresponding cutter location Q _i(i=0,1 ..., the 2n) height on the tool axis direction obtains the highest cutter location Q _jWith minimum cutter location Q _k, if j=0 or j=2n, then the highest cutter location Q _jBe the cutter location of asking, cutter location calculates and finishes, otherwise carries out 4.; 4. calculate the highest cutter location Q _jWith minimum cutter location Q _kBetween apart from d, if d is less than the deviation threshold of setting, the highest cutter location Q _jBe the cutter location of asking, EOP (end of program), otherwise with P _J-1P _J+1For 1. effective line segment returns step.

Figure 11 is tack slotting cutter among the present invention and cutting knife site, ball end mill limit calculating synoptic diagram.Tack slotting cutter, the unification of tack slotting cutter are the annulus slotting cutter, and R is a tool radius, and its value is 4.0, and r is the cutter radius of corner, and its value is 2.0, and v is the vector of unit length of cutter shaft A, and some P ' is the projection of P on A, and l is cutter-contact point P _cTo the distance of A, try to achieve effective cutter location P by formula (9) _s

The multiaxis processing cutter rail of Figure 12 for generating in the embodiment of the invention.Wherein Figure 12 is the cutter rail that generates based on the inventive method a), Figure 12 b) vow Figure 12 c for each cutter location and the method thereof that generate) be Figure 12 b) center choosing enlarged drawing partly.

The multi-shaft numerical control machining knife rail generating method of other product triangle grid models is the same.

Claims (4)

1. the multi-shaft numerical control machining knife rail generating method of a product triangle grid model is characterized in that steps in sequence is: 1) improve R ^*-tree obtains being suitable for the dynamic space index structure R of storage products triangle grid model ^*The S-tree is improved R ^*-tree dynamic space index data structure obtains R ^*The method of S-tree is specifically: be expressed as four-dimensional some object (x, y, z, r with tri patch and index node MBR are unified ₁), x wherein, y, z are the MBR centre coordinate, r ₁Be MBR circumsphere radius value,, make up product triangle grid model dynamic space index structure, based on R by the cluster sub-clustering of tri patch set ^*The S-tree is set up the dynamic space index structure of product triangle grid model, and wherein MBR represents minimum area-encasing rectangle; 2) based on triangle grid model dynamic space index structure, tool setting rail cutting plane and triangle grid model are asked friendship, obtain the cross-section data point, its acquisition methods is specifically: by the position relation of cutter rail cutting plane and each layer of triangle grid model space index structure node, successively search each the layer index node that intersects with cutter rail cutting plane, extract the data node that intersects with cutter rail cutting plane, each limit of extracting data inter-node tri patch and cutter rail cutting plane asked hand over and overlapping point that deletion is asked in the intersection point obtains the cross-section data point, with the intersection point that obtains as the cross-section data point; 3) based on triangle grid model dynamic space index structure, regional neighbour's tri patch of inquiry cross-section data point, the method that adopts the area averaging method to calculate the respective cross-section data point vows, its computing method specifically: employing R ^*S-tree range query algorithm is searched fast apart from the tri patch of cross-section data point less than ζ, the product that each tri patch area and its per unit system the are vowed summation that adds up, the method that the gained result asks for corresponding cross-section data point divided by the area sum of each tri patch is vowed that wherein ζ represents the coverage threshold value; 4) vow according to cross-section data point and method thereof and determine tool axis that based on triangle grid model dynamic space index structure, inquiry is apart from the tri patch set of tool axis less than tool radius, with it as instantaneous machining area; 5) according to the position orientation relation between each tri patch in cutter and the instantaneous machining area, employing face is tangent, tangent or the tangent cutter Location Calculation Method in summit in limit is obtained corresponding cutter location, and in the cutter location that obtains, be taken at the highest cutter location in position on the cutter axis orientation as the corresponding cutter location of current cross-section data point, its method is specifically: each cross-section data is put each tri patch in the corresponding instantaneous machining area, at first adopt the face tangent method to calculate cutter location, if the cutter location that is obtained is effective, then with the cutter location of this cutter location as this tri patch correspondence, otherwise three limits of tri patch and three summits are carried out respectively the tangent cutter spacing in limit is calculated and the tangent cutter spacing in summit is calculated, in the effective cutter location that obtains, be taken at the cutter location of the highest cutter location in position on the cutter axis orientation as this tri patch correspondence, relatively the height of the corresponding cutter location of each tri patch on cutter axis orientation is taken at cutter location the highest on the cutter axis orientation as the corresponding cutter location of current cross-section data point; 6) adopt the cutter location of minimum spanning tree method pair cross-section data point correspondence to sort, generate the multi-shaft numerical control machining knife rail of triangle grid model.

2. the multi-shaft numerical control machining knife rail generating method of product triangle grid model as claimed in claim 1, it is characterized in that: in the tangent cutter location computing method of step 5) face, with ball end mill, tack slotting cutter and annulus slotting cutter are unified to be the annulus slotting cutter, vow the property calculation cutter location vertical according to cutter-contact point place tool surface method with tri patch, specifically: establishing current tri patch is T, unified tack slotting cutter, ball end mill is the annulus slotting cutter, tool radius is R, radius of corner is r, v is the vector of unit length of cutter shaft A, n is that the per unit system of tri patch T is vowed P _cFor the points of tangency on cutter and plane, T place is a cutter-contact point, P ₀Be the intersection point on A and plane, T place, P _sBe the cutter location of tri patch T correspondence, v _rBe P _sPoint to p _cThe vector in the corresponding fillet center of circle, by formula (1):

Get P _sWith P ₀Between apart from t, in conjunction with P ₀, v, v _r, n tries to achieve P _s, P _c, judge P _cWhether in T inside, if at T inside, then P _sEffectively, otherwise P _sIt is invalid..

3. the multi-shaft numerical control machining knife rail generating method of product triangle grid model as claimed in claim 1, it is characterized in that: in the tangent cutter location computing method in step 5) limit, for ball end mill or tack slotting cutter, vow the property calculation cutter location vertical according to cutter-contact point place tool surface method with place, limit straight line, adopt the iteration Method cutter location extract the effective range on limit for the annulus slotting cutter after, specifically be for ball end mill or tack slotting cutter: establish when the front be E, R is tack slotting cutter or ball end mill radius, A is a tool axis, v is the vector of unit length of A, L is the straight line at E place, limit, and n is the vector of unit length of L, P ₀, P ₁Be respectively A and E and go up 2 nearest points, P _sBe cutter location, P _cBe cutter-contact point, f is by P ₁And vector The plane of determining, P _tBe P _sSubpoint on f, v _cFor by P _cPoint to P _tVector, v _tBe the vector of f perpendicular to L, by formula (2):

Ask for P _sWith P ₀Apart from t, with its substitution formula (3):

Calculate P _s, P _c, judge P _cWhether in E inside, as P then in E inside _sEffectively; For the annulus slotting cutter, look in the other direction along tool axis, the part that is covered by cutter is the effective range that needs iterative computation in the tangent cutter location computation process in limit, obtain after the effective range its effective line segment when calculating cutter location, effectively evenly getting the individual point of 2n+1 (n＞1) on the line segment, each point is carried out the tangent cutter spacing in summit calculate, iterative obtains final cutter location, and concrete steps are as follows: 1. effectively evenly getting individual some P of 2n+1 (n＞1) on the line segment _i(i=0,1 ..., 2n); 2. each point is carried out the tangent cutter spacing in summit and calculate, obtain corresponding cutter location Q _i(i=0,1 ..., 2n); 3. more corresponding cutter location Q _i(i=0,1 ..., the 2n) height on the tool axis direction obtains the highest cutter location Q _jWith minimum cutter location Q _k, if j=0 or j=2n, then the highest cutter location Q _jBe the cutter location of asking, cutter location calculates and finishes, otherwise carries out 4.; 4. calculate the highest cutter location Q _jWith minimum cutter location Q _kBetween apart from d, if apart from d less than the deviation threshold of setting, the highest cutter location Q _jBe the cutter location of asking, EOP (end of program), otherwise with P _J-1P _J+1For 1. effective line segment returns step.

4. the multi-shaft numerical control machining knife rail generating method of product triangle grid model as claimed in claim 1, it is characterized in that: in the tangent cutter location computing method in step 5) summit, ball end mill, tack slotting cutter and the unification of annulus slotting cutter are the annulus slotting cutter, calculate cutter location according to the relation of the position between cutter-contact point and the tool axis, specifically: establishing R is tool radius, and r is the cutter radius of corner, and v is the vector of unit length of cutter shaft A, point P ' is the projection of P on A, and l is cutter-contact point P _cTo the distance of A, by formula (4):

Try to achieve effective cutter location P _s

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