发明内容 SUMMARY

[0005] 发明目的:本发明旨在提供一种运算量少、计算时间短、计算效率高的自适应性的有效分层切片方法，该方法根据成型件的表面特征，可以自动调节切片的厚度，能够显著提高制件表面质量和几何精确度。 [0005] The object of the invention: The present invention aims to provide a small amount of calculation, calculation time is short, computationally efficient and effective adaptive slicing method according to the surface characteristics of molded parts, can automatically adjust the thickness of slices can significantly improve workpiece surface quality and geometric accuracy.

[0006] 技术方案:一种基于选择性激光烧结的分层切片方法，其特征在于，包括以下步骤: [0006] Technical Solution: A slicing method based on selective laser sintering, characterized in that it comprises the following steps:

[0007] (1)读取待加工零件的STL文件； [0007] (1) read the STL file of the part to be machined;

[0008] (2)确定分层方向、分层厚度的最大最小值、台阶误差的最大值以及表面粗糙度的最大值； [0008] (2) determining the direction of layering, layer thickness of maximum and minimum, maximum step error and the maximum surface roughness;

[0009] (3)将STL模型里的三角面片在分层方向上进行第一层切片； [0009] (3) The STL model in the triangular faces in the direction of the first layer layered slice;

[0010] (4)根据层平面轮廓多边形的各条边以及与其相关的各三角面片，计算出下一层满足精度要求的最小分层厚度； [0010] (4) based on respective sides of the layer plane contour polygons and triangles associated with each piece, the next layer is calculated layer thickness accuracy to meet the minimum requirements;

[0011] (5)根据每层层厚对该层切片的交点集合组进行排序处理得到该切平面的轮廓线。 [0011] (5) sorting process to obtain the contour tangent plane according to the thickness of each layer of sliced ​​intersection set group.

[0012] 所述步骤(4)中，计算下一层满足精度要求的最小分层厚度的具体步骤为: [0012] the step (4), the calculation of the next layer of concrete steps to meet the accuracy requirements of the minimum layer thickness is:

[0013] 设STL模型的三角面片在分层方向上的最大和最小坐标值分别为叾_和Z_，允许的台阶误差最大值为，表面粗糙度极值为Rb，每层的最大烧结厚度和最小烧结厚度分别为UP h _， [0013] Let STL model triangular faces maximum and minimum coordinate value in the direction of stratification were 叾 _ and Z_, the maximum permissible error for the stairs, the surface roughness of extreme value Rb, the maximum sintering of each layer thickness and the minimum thickness were sintered UP h _,

[0014] 假设在层高为Z的层面，一个三角面片F与切平面S相交，其交线的两个端点坐标为PJxd γ1; Zi)和P2(x2, y2, z)，其交线的中点PQ(x。，y。，z。)的坐标可以通过下列算式求得: [0014] Assuming storey level of Z, a triangular facet F and S tangent plane intersects the line of intersection of the two endpoints of its coordinates PJxd γ1; Zi) and P2 (x2, y2, z), which cross the line the midpoint of PQ (... x, y, z) coordinates can be obtained by the following formula:

[0015] x0= (x !+x2)/2 ； [0015] x0 = (! X + x2) / 2;

[0016] y0= (y ； [0016] y0 = (y;

[0017] Z0= Z != Z 2= z ； ! [0017] Z0 = Z = Z 2 = z;

[0018] 以除ΡΛ之外任意一点P。 [0018] In addition to ΡΛ any point P. 作一投影面M，该平面与Ρ Λ垂直，经过Ρ。 Make a projection plane M, the plane Ρ Λ vertical, through Ρ. 点，由此可得该平面的点法式方程: Point, which can get the point of the French plane equation:

[0019] (x2-xi) (χ-χ0) + (y2-yi) (y-y0) = 0 ； [0019] (x2-xi) (χ-χ0) + (y2-yi) (y-y0) = 0;

[0020] 由可允许的最大台阶误差δ _可得该三角面片F允许的最大分层厚度: [0020] step by the maximum permissible error δ _ available to the triangular facet F maximum allowable layer thickness:

[0021] htnaxl= δ nax/cos θ ； [0021] htnaxl = δ nax / cos θ;

[0022] 其中θ为三角面片F与切片面S的夹角； [0022] where θ is triangular facet F and S slice surface angle;

[0023] 由可允许的表面粗糙度的最大值Rb可得三角面片F允许的最大分层厚度: [0023] by the allowable maximum surface roughness Rb available triangular facet F maximum permissible layer thickness:

[0024] htnax2= (R b+2.04067-0.22 α +0.001368 α 2) /0.06722 ； [0024] htnax2 = (R b + 2.04067-0.22 α +0.001368 α 2) /0.06722;

[0025] 其中α为三角面片F与切平面法S向量的夹角； [0025] where α is the angle between the triangular facet F and S vector tangent plane method;

[0026] 计算Μ平面与三角面片F的上交点P3 (x3, y3, z3)，交点距切平面S的距离为: [0026] Calculation Μ plane triangular facet F to be paid to the point P3 (x3, y3, z3), cross-cut from the pitch plane S is:

[0027] htnax3= z 3-z ； [0027] htnax3 = z 3-z;

[0028]取 ht= min {h tnaxl, htnax2, htnax3}， [0028] Take ht = min {h tnaxl, htnax2, htnax3},

[0029] ght>h_，则利用三维实体的点、面、边拓扑关系找到与三角面片F相邻的三角面片，并继续计算相邻三角面片的分层厚度，并与UP h _相比较，若所有ht都在h _和hmax之间，则取h tmin为下一层切片的厚度； [0029] ght> h_, the use of three-dimensional solid point, surface, edge topology found with triangular facets F adjacent triangular faces, and layer thickness triangular facets adjacent to continue the calculation, and the UP h _ compared if all ht are between h _ and hmax, then take the next layer h tmin slice thickness;

[0030] 若ht< h min，则停止计算，取hmin为下一层切片的厚度； [0030] If ht <h min, then stop counting, taking hmin for the thickness of the lower layer of slices;

[0031] 若遍历该层所有相交三角面片，得到的ht均大于等于h _，则取h_为下一层切片的厚度。 [0031] If the layer traverse all intersecting triangular faces, and get ht were more than equal to h _, then take h_ thickness of the next layer slices.

[0032] 所述步骤(5)中根据每层层厚对该层切片的交点集合组进行排序处理得到该切平面的轮廓线的具体步骤为:由步骤(4)得到下一层层厚，找到一个与下一层切平面相交的三角面片FJA，B, C}，求得相交的两个交点，根据拓扑关系找到与三角面片F。 [0032] The step (5) in accordance with each slice thickness of the layer set intersection group sorting process to obtain concrete steps outline the cut plane is: the step (4) to give the next layers of thick, find a cut and the next layer plane intersecting triangular facets FJA, B, C}, obtained by the intersection of two intersecting, according to the topology found with triangular facets F. 相邻的三角面片匕，并求得下一个交点，依次遍历该层所有相交三角面片直至到达第一个三角面片F。 Adjacent triangular faces dagger, and seek the next intersection, turn to traverse all the layers until you reach the intersection of triangular facets first triangular facets F. 结束，得到该层切片的轮廓线。 The end to give the layer slice contour.

[0033] 有益效果:本发明在确定下一层的分层厚度时，不需要多次的试切过程，只需要利用当前层片多边形截面轮廓上各边的顶点坐标，以及与各边相关的三角面片对应关系和三维实体的点、面、边的拓扑信息，就可以直接计算出下一层满足分层精度要求(台阶误差和表面粗糙度)的分层厚度，简化了计算，提高了计算效率。 [0033] beneficial effects: in the present invention is determined by layer thickness of the next layer, the cutting process does not require the test several times, only need to use the current layer sheet polygon vertex coordinates of the cross-sectional profile of each side, as well as associated with each side triangular facets corresponding points and the relationship between three-dimensional solid, surface, edge topology information, you can directly calculate the next level to meet the accuracy requirements layered (step error and surface roughness) of the layer thickness, simplifies the calculation and improve computational efficiency. 通过自适应调整切片的厚度来控制成型的速度和精度，从而可以有效的提高生产效率和生产质量，尤其是针对结构比较复杂的成型件，在保证成型速度的前提下，工件的精度得到了很大的提高。 By adjusting the thickness of the slice adaptive to control the speed and precision molding, which can effectively improve production efficiency and quality, especially for complex structure of molded parts, molded in ensuring the premise of speed, accuracy of the workpiece has been very greatly improved.