阅读说明：本技术 一种基于随机点的3d打印填充路径生成方法 (3D printing filling path generation method based on random points ) 是由 王华楠 郝星星 于 2020-10-21 设计创作，主要内容包括：本发明公开了一种基于随机点的3D打印填充路径生成方法,包括如下步骤根据3D打印设备以及打印精度确定合适的层厚和随机点密度,并根据层厚和三维模型文件得到每一层需要打印的外轮廓；根据随机点密度和轮廓外接矩形面积获取一定数量的内部随机点；设定点与点之间距离阈值,在外轮廓和内部随机点中删除距离过近的点,在外轮廓点之间对距离过远的点进行内插；根据轮廓点和内部随机点生成网格,采用增加网格线或删除网格线算法对网格进行优化；根据优化后的网格生成不间断打印路径。该方法根据点与点的距离阈值确定删除或增加点,对已有的点集进行网格划分,并对划分好的网格进行优化,确保网格中所有点的度为偶数,最后根据优化后的网格生成不间断打印路径。(The invention discloses a 3D printing filling path generation method based on random points, which comprises the following steps of determining proper layer thickness and random point density according to 3D printing equipment and printing precision, and obtaining an outer contour to be printed of each layer according to the layer thickness and a three-dimensional model file; obtaining a certain number of internal random points according to the density of the random points and the area of a rectangle circumscribed to the outline; setting a distance threshold value between points, deleting points with too close distance from the outer contour and the internal random points, and interpolating points with too far distance between the points of the outer contour; generating grids according to the contour points and the internal random points, and optimizing the grids by adopting an algorithm of adding grids or deleting grids; and generating an uninterrupted printing path according to the optimized grid. The method determines to delete or add points according to the distance threshold value between the points, carries out grid division on the existing point set, optimizes the divided grids, ensures that all points in the grids are even numbers, and finally generates an uninterrupted printing path according to the optimized grids.)

1. A3D printing filling path generation method based on random points is characterized by comprising the following steps:

determining appropriate layer thickness and random point density according to the 3D printing equipment and the printing precision, and obtaining the outline to be printed of each layer according to the layer thickness and the three-dimensional model file;

obtaining a certain number of internal random points according to the density of the random points and the area of a rectangle circumscribed to the outline;

setting a distance threshold value between points, deleting points with too close distance from the outer contour and the internal random points, and interpolating points with too far distance between the points of the outer contour;

generating grids according to the contour points and the internal random points, and optimizing the grids by adopting an algorithm of adding grids or deleting grids;

and generating an uninterrupted printing path according to the optimized grid.

2. The method of claim 1, wherein: wherein, the outline tangent plane to be printed on each layer is obtained by intersecting with the triangular mesh of the STL file, and the following method is specifically adopted:

obtaining that the current tangent plane is Z-Z0 according to the layer thickness, searching all triangles intersected with the current tangent plane and optionally selecting one triangle as an initial triangle; and sequentially solving intersection points of the triangles and the tangent plane, putting the intersection points into the result point set according to the topological sequence of the triangles, when a plurality of contours exist in the current layer, optionally selecting any one of the remaining triangles as an initial triangle, and repeating the process to obtain the result point set of the plurality of contours.

3. The method of claim 1, wherein: the internal random points are obtained by the density of the random points and the area of a rectangle circumscribed to the outline, and the following method is specifically adopted:

obtaining the maximum value and the minimum value in the x direction and the maximum value and the minimum value in the y direction from one or more contour point sets of the current layer; constructing a circumscribed rectangle of the contour point set: calculating the area s of the circumscribed rectangle according to the coordinate values of the left lower corner point and the point coordinate values of the right upper corner of the rectangle, and calculating the number of random points generated in the rectangle according to the area s of the rectangle and the density f of the random points to be s multiplied by f; uniformly and randomly scattering points in the external rectangle to obtain a point set of random points in the outline; and deleting random points outside the contour from the point set of the random points inside the contour.

4. The method of claim 1, wherein: when deleting points that are too close:

and deleting one of the contour points when the distance between the contour points and the contour points is smaller than a distance threshold, deleting one of the internal random points when the distance between the internal random points and the internal random points is smaller than the distance threshold, and deleting the internal random points when the distance between the contour points and the internal random points is smaller than the distance threshold.

Firstly, judging contour points: if other contour points or internal random points exist in a circle which takes the current contour point as the center of the circle and takes the distance threshold value as the radius, deleting the points in the circle;

judging the internal random point, if there are other points in the circle taking the current internal random point as the center of the circle and the distance threshold as the radius, deleting the points in the circle;

and judging contour points, and if the distance of the contour line formed by two adjacent points is greater than a distance threshold value which is 2 times, interpolating the points between the two points by taking the distance threshold value as a distance.

5. The method of claim 1, wherein: the grid is a Delaunay triangular grid or a Voronoi grid.

6. The method of claim 5, wherein: when the grid is optimized, a grid line deleting algorithm is adopted, and the specific mode is as follows:

calculating the degree of each point in the grid division result, optionally selecting a point with an odd degree as a current point, and forming a set omega 1 by points connected with the current point;

judging whether points with odd numbers exist in the set omega 1, if not, forming a set omega 2 by the points connected with the middle point of the omega 1, judging the points in the omega 2, and if one point exists in the omega 1 and also exists in the omega 2, deleting the point in the omega 2;

judging whether points with odd numbers exist in the set omega 2, if not, forming a set omega 3 by the points connected with the middle point of the omega 2, judging the points in the omega 3, and if one point exists in the omega 1 or the omega 2 and also exists in the omega 3, deleting the point in the omega 3;

obtaining two or more point sets omega 1, omega 2.. omega n with connection relations by adopting the method, wherein points with odd degrees exist in the omega n, and obtaining a connection path A-B-C-. from the current point to the points with odd degrees in the omega n from the omega 1, omega 2.. omega n;

deleting the connecting lines formed by the connecting paths in the grid;

the above steps are repeated until the degree of all points in the grid is even.

7. The method of claim 5, wherein: the optimization criterion when optimizing the Delaunay triangular mesh is to add a grid line algorithm, and the specific steps are as follows:

calculating the degree of each point in the Delaunay triangular mesh division result, optionally selecting a point with an odd degree as a current point, and forming a set omega 1 by points connected with the current point;

and judging whether points with odd numbers exist in the set omega 1, if not, forming a set omega 2 by the points connected with the omega 1. Judging a point in the omega 2, and if one point exists in the omega 1 and also exists in the omega 2, deleting the point in the omega 2;

judging whether points with odd numbers exist in the set omega 2, if not, forming a set omega 3 by the points connected with the omega 2, judging the points in the omega 3, and if one point exists in the omega 1 or the omega 2 and also exists in the omega 3, deleting the point in the omega 3;

the method is adopted to obtain two or more point sets omega 1 and omega 2 having a connection relation, wherein points with odd numbers exist in omega n. Obtaining a connecting path A-B-C-from a current point to a point of odd degree in the omega n from the omega 1, the omega 2.. omega n;

adding connecting lines in the Delaunay triangular mesh according to the connecting paths, and specifically comprising the following steps:

a first point i and a second point j in a connecting path form a current working line segment, a triangle containing the current working line segment is found in a Delaunay triangular mesh, the triangle is used as a current working triangle, and an included hexagon is constructed in the current working triangle;

finding a line segment which is parallel to the current working line segment and is closest to the current working line segment in the hexagon as an adding line segment, and connecting the end point of the current working line segment with the end point which is closest to the adding line segment to form a parallelogram;

adding three segments of the parallelogram except the current working segment into the grid as newly added connecting lines; the above steps are repeated until the degree of all points in the grid is even.

8. The method of claim 6, wherein: the generation algorithm of the uninterrupted printing path is an Euler loop algorithm for solving an undirected graph, wherein the Euler loop algorithm for solving the undirected graph is a Hierholzer algorithm.

9. The method of claim 6, wherein: wherein the starting point of the euler loop is selected to satisfy the nearest principle: in the first layer, one point is selected as the initial point of the euler path, and in the next layer, the point closest to the initial point of the previous layer is selected as the initial point of the euler path of the layer.

Technical Field

The invention relates to a 3D printing technology, in particular to a 3D printing filling path generation method based on random points.

Background

The 3D printing technology firstly utilizes computer aided design software to construct or obtain a three-dimensional solid model through reverse engineering, then the three-dimensional solid model generates section layers by layer through slicing software, and a three-dimensional solid is obtained in a layer-by-layer processing mode. Because the cross section is processed layer by using liquid, powder or sheet materials in the printing process, objects in any shapes can be processed by the technology. Therefore, in some fields which cannot be completed by the traditional processing technology, the 3D printing technology is developed rapidly, and is widely applied to the fields of buildings, aerospace, machinery, biomedicine and the like. Although 3D printing can shorten the development cycle of products and reduce the production cost, since a model generally has a large number of layers, and the filling path of each layer has an influence on the formed entity, finding a good filling path is always one of the key technologies for 3D printing.

The currently common 3D printing fill path mainly includes two types. One is a parallel reciprocating straight-line path, and the path is characterized in that the main body part of the path consists of a large number of equidistant parallel straight-line segments, so that the filling efficiency is high, meanwhile, the path generation algorithm is simple and reliable, and the path generation speed is high; the problem is that the filling accuracy at the corners is poor due to the large number of path connecting corners. Meanwhile, from the aspect of single-layer strength, the parallel linear filling cannot bear large bending moment. The other is a profile parallel path, and the path has high filling precision due to the fact that a large number of corners are avoided, and can well avoid the problems of stress concentration and the like of a forming material in the forming process; however, for complex parts with more cavities, the path generation algorithm needs to deal with the problems of self-intersection, mutual intersection and the like after outline deviation, and relates to the problem of polygon Boolean operation, so that the algorithm is relatively complex, the path generation speed is slow, a large number of curves exist in the generated path track, and the filling efficiency is low. The existing path generation method basically combines the two paths, adopts a profile parallel path at the edge of a section profile to ensure the surface forming precision, and adopts a parallel reciprocating linear path for internal filling to improve the filling efficiency.

However, the influence of the filling path on the strength of the single layer is not considered in the current parallel reciprocating straight line path generation process, so that the condition that the parallel straight line bears large bending moment is ignored, and the application of the 3D printing technology is limited to a certain extent. This can lead to 3D printing techniques that are difficult to meet the requirements of various fields for the models to withstand large bending moments. Meanwhile, under the condition of the determined line spacing, the linear filling rate is low, and the requirement of high filling rate cannot be met.

In addition, the existing linear filling algorithm is simple and quick, but the fact that a single-layer profile filled linearly cannot bear large bending moment is not considered, so that the overall strength of the structure is influenced; the contour offset algorithm has a large amount of graph self-intersection operation, so that the algorithm efficiency is low, meanwhile, contour offset filling is also straight line parallel offset, so that the contour offset filling cannot bear larger bending moment parallel to the contour line, and in addition, under the condition of given straight line spacing, the filling rate of the straight line filling is lower.

Disclosure of Invention

According to the problems in the prior art, the invention discloses a 3D printing filling path generation method based on random points, which specifically comprises the following steps:

determining appropriate layer thickness and random point density according to the 3D printing equipment and the printing precision, and obtaining the outline to be printed of each layer according to the layer thickness and the three-dimensional model file;

obtaining a certain number of internal random points according to the density of the random points and the area of a rectangle circumscribed to the outline;

setting a distance threshold value between points, deleting points with too close distance from the outer contour and the internal random points, and interpolating points with too far distance between the points of the outer contour;

generating grids according to the contour points and the internal random points, and optimizing the grids by adopting an algorithm of adding grids or deleting grids;

and generating an uninterrupted printing path according to the optimized grid.

Further, the outline tangent plane to be printed on each layer is obtained by intersecting with the triangular mesh of the STL file, specifically adopting the following method:

obtaining that the current tangent plane is Z-Z0 according to the layer thickness, searching all triangles intersected with the current tangent plane and optionally selecting one triangle as an initial triangle; and sequentially solving intersection points of the triangles and the tangent plane, putting the intersection points into the result point set according to the topological sequence of the triangles, when a plurality of contours exist in the current layer, optionally selecting any one of the remaining triangles as an initial triangle, and repeating the process to obtain the result point set of the plurality of contours.

Further, the internal random points are obtained by the density of the random points and the area of a rectangle circumscribed to the outline, and the following method is specifically adopted:

obtaining the maximum value and the minimum value in the x direction and the maximum value and the minimum value in the y direction from one or more contour point sets of the current layer; constructing a circumscribed rectangle of the contour point set: calculating the area s of the circumscribed rectangle according to the coordinate values of the left lower corner point and the point coordinate values of the right upper corner of the rectangle, and calculating the number of random points generated in the rectangle according to the area s of the rectangle and the density f of the random points to be s multiplied by f; uniformly and randomly scattering points in the external rectangle to obtain a point set of random points in the outline; and deleting random points outside the contour from the point set of the random points inside the contour.

Further, when deleting points that are too close in distance:

and deleting one of the contour points when the distance between the contour points and the contour points is smaller than a distance threshold, deleting one of the internal random points when the distance between the internal random points and the internal random points is smaller than the distance threshold, and deleting the internal random points when the distance between the contour points and the internal random points is smaller than the distance threshold.

Firstly, judging contour points: if other contour points or internal random points exist in a circle which takes the current contour point as the center of the circle and takes the distance threshold value as the radius, deleting the points in the circle;

judging the internal random point, if there are other points in the circle taking the current internal random point as the center of the circle and the distance threshold as the radius, deleting the points in the circle;

and judging contour points, and if the distance of the contour line formed by two adjacent points is greater than a distance threshold value which is 2 times, interpolating the points between the two points by taking the distance threshold value as a distance.

Further, the mesh is a Delaunay triangular mesh or a Voronoi mesh.

Further, a grid line deleting algorithm is adopted when the grid is optimized, and the specific mode is as follows:

calculating the degree of each point in the grid division result, optionally selecting a point with an odd degree as a current point, and forming a set omega 1 by points connected with the current point;

judging whether points with odd numbers exist in the set omega 1, if not, forming a set omega 2 by the points connected with the middle point of the omega 1, judging the points in the omega 2, and if one point exists in the omega 1 and also exists in the omega 2, deleting the point in the omega 2;

judging whether points with odd numbers exist in the set omega 2, if not, forming a set omega 3 by the points connected with the middle point of the omega 2, judging the points in the omega 3, and if one point exists in the omega 1 or the omega 2 and also exists in the omega 3, deleting the point in the omega 3;

obtaining two or more point sets omega 1, omega 2.. omega n with connection relations by adopting the method, wherein points with odd degrees exist in the omega n, and obtaining a connection path A-B-C-. from the current point to the points with odd degrees in the omega n from the omega 1, omega 2.. omega n;

deleting the connecting lines formed by the connecting paths in the grid;

the above steps are repeated until the degree of all points in the grid is even.

Further, the optimization criterion when optimizing the Delaunay triangular mesh is to add a grid line algorithm, and the specific steps are as follows:

calculating the degree of each point in the Delaunay triangular mesh division result, optionally selecting a point with an odd degree as a current point, and forming a set omega 1 by points connected with the current point;

and judging whether points with odd numbers exist in the set omega 1, if not, forming a set omega 2 by the points connected with the omega 1. Judging a point in the omega 2, and if one point exists in the omega 1 and also exists in the omega 2, deleting the point in the omega 2;

judging whether points with odd numbers exist in the set omega 2, if not, forming a set omega 3 by the points connected with the omega 2, judging the points in the omega 3, and if one point exists in the omega 1 or the omega 2 and also exists in the omega 3, deleting the point in the omega 3;

the method is adopted to obtain two or more point sets omega 1 and omega 2 having a connection relation, wherein points with odd numbers exist in omega n. Obtaining a connecting path A-B-C-from a current point to a point of odd degree in the omega n from the omega 1, the omega 2.. omega n;

adding connecting lines in the Delaunay triangular mesh according to the connecting paths, and specifically comprising the following steps:

a first point i and a second point j in a connecting path form a current working line segment, a triangle containing the current working line segment is found in a Delaunay triangular mesh, the triangle is used as a current working triangle, and an included hexagon is constructed in the current working triangle;

finding a line segment which is parallel to the current working line segment and is closest to the current working line segment in the hexagon as an adding line segment, and connecting the end point of the current working line segment with the end point which is closest to the adding line segment to form a parallelogram;

adding three segments of the parallelogram except the current working segment into the grid as newly added connecting lines; the above steps are repeated until the degree of all points in the grid is even.

Further, the generation algorithm of the uninterrupted printing path is an euler loop algorithm for solving an undirected graph, wherein the euler loop algorithm for solving the undirected graph is a Hierholzer algorithm.

Wherein the starting point of the euler loop is selected to satisfy the nearest principle: in the first layer, one point is selected as the initial point of the euler path, and in the next layer, the point closest to the initial point of the previous layer is selected as the initial point of the euler path of the layer.

By adopting the technical scheme, the 3D printing filling path generation method based on the random points determines the slice layer height, the random point density and the distance threshold between the points according to the precision of a printer and the printing requirement, obtains the printing contour of each layer according to a model and the slice layer height, randomly scatters the points in the circumscribed rectangle of the contour, determines to delete or increase the points according to the distance threshold between the points, carries out grid division on the existing point set, optimizes the divided grid, ensures that all the points in the grid are even numbers, and finally generates an uninterrupted printing path according to the optimized grid, can effectively improve the section filling rate by the random point-based filling method under the limitation of the same distance threshold, and can be enhanced in a limited way compared with a linear filling algorithm or a contour offset algorithm, the ability of moment is born to current layer to the holistic intensity of reinforcing model.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments described in the present application, and other drawings can be obtained by those skilled in the art without creative efforts.

FIG. 1 is a flow chart of the method of the present invention;

FIG. 2 is a schematic view of the outer profile of the current printed layer of the present invention;

FIG. 3 is a schematic diagram of the generation of internal random points with a random point density of 50 according to the present invention;

FIG. 4 is the result of deletion and interpolation when the threshold value of the distance between a defined point and a point is 1mm in the invention;

FIG. 5 is a schematic diagram of Delaunay triangle mesh partitioning in the present invention;

FIG. 6 is a schematic diagram of a deleted grid optimization algorithm of the present invention;

FIG. 7 is a schematic diagram of a straight-line fill algorithm of the present invention;

FIG. 8 is a diagram illustrating the filling amount of two filling algorithms under the same distance threshold limit in the present invention;

FIG. 9 is a diagram of a printed object according to the delete grid optimization algorithm of the present invention

FIG. 10 is a flow chart of the method of the present invention.

Detailed Description

In order to make the technical scheme and advantages of the present invention clearer, the following describes the technical scheme in the embodiment of the present invention clearly and completely with reference to the attached drawings in the embodiment of the present invention:

as shown in fig. 1, a method for generating a 3D printing fill path based on random points specifically includes the following steps:

s1, determining appropriate layer thickness and random point density according to the 3D printing equipment and the printing precision, and obtaining the outline to be printed of each layer according to the layer thickness and the three-dimensional model file;

s2, obtaining a certain number of internal random points according to the density of the random points and the area of the outline circumscribed rectangle;

s3, setting a distance threshold value between points, deleting points with too close distance from the outer contour and the inner random points, and interpolating points with too far distance between the outer contour points;

s4, generating grids according to the contour points and the internal random points, and optimizing the grids by adopting an algorithm of adding grids or deleting grids;

and S5, generating an uninterrupted printing path according to the optimized grid.

Further, the three-dimensional model file in S1 is an STL model file.

Further, the printing outline of each layer is obtained by intersecting a tangent plane and a triangular mesh of the STL file, and the method specifically comprises the following steps:

s11, obtaining a current tangent plane Z-Z0 according to the layer thickness;

s12, finding all the triangles intersected with the current tangent plane;

s13, selecting a triangle as an initial triangle;

and S14, sequentially solving the intersection points of the triangle and the tangent plane, and putting the intersection points into the result point set according to the topological sequence of the triangle. When there are multiple contours in the current layer, optionally any one of the remaining triangles is used as the initial triangle, and repeating S14 to obtain a result point set of the multiple contours.

In S2: the generation of the random points is controlled by the density of the random points and the area of a rectangle circumscribed to the outline, and the method specifically comprises the following steps:

s21: and obtaining the maximum value x _ max, the minimum value x _ min, the maximum value y _ max and the minimum value y _ min in the x direction from one or more contour point sets of the current layer.

S22: constructing an external rectangle of the contour point set, wherein the coordinates of the lower left corner point of the rectangle are (x _ min, y _ min), the coordinates of the upper right corner point of the rectangle are (x _ max, y _ max), calculating the area s of the external rectangle, and calculating the number of random points generated in the rectangle according to the area s of the rectangle and the density f of the random points to be s multiplied by f

S23: uniformly and randomly scattering points in the external rectangle to obtain a point set of random points in the outline

S24: and deleting random points outside the contour from the point set of the random points inside the contour.

In S3: the point and the point meet the requirement of a distance threshold, and the relationship between the point and the point comprises the relationship between a contour point and a contour point, between an internal random point and an internal random point, and between the contour point and the internal random point. The specific operation is as follows:

(1) firstly, judging the contour points, and deleting the points in the circle if other contour points or internal random points exist in the circle taking the current contour point as the center of the circle and the distance threshold value as the radius.

(2) And judging the internal random point, and deleting the points in the circle, wherein the current internal random point is taken as the center of the circle, and the distance threshold is taken as the radius.

(3) And judging contour points, and if the distance of the contour line formed by two adjacent points is more than a distance threshold value which is two times, directly carrying out point interpolation on the two points by taking the distance threshold value as the distance.

Further, the mesh is a Delaunay triangular mesh or a Voronoi mesh.

When the optimization criterion is a grid line deletion algorithm, the method specifically comprises the following steps:

and S51, calculating the degree of each point in the grid division result. The calculation method is to count the number of points connected with the current point. And if the number of the points connected with the current point is i, the degree of the current point is i.

S52, selecting one degree odd number point as current point, the points connected with the current point form a set omega 1

And S53, judging whether points with odd degrees exist in the set omega 1, if not, forming a set omega 2 by the points connected with the middle point of the omega 1. A point in Ω 2 is judged, and if a point exists in both Ω 2 and Ω 1, the point is deleted in Ω 2.

S54, whether the points with odd degree exist in the set omega 2 is judged. If not, the points connected to the midpoint of Ω 2 form the set Ω 3. A point in Ω 3 is judged, and if a point exists in Ω 1 or Ω 2, and also in Ω 3, the point is deleted in Ω 3.

S55 obtains two or more point sets Ω 1, Ω 2.. Ω n having a connection relationship according to the above method. Where there are odd numbered points in Ω n. One connection path a-B-C-. X from the current point to a point in Ω n of odd degree is derived from Ω 1, Ω 2.

And S56, deleting the connecting lines formed by the connecting paths in the grid.

S57, repeating S51-S56 until all points in the grid are even.

Further, if the optimization criterion is to add a grid line algorithm, the specific steps are as follows:

and 5.1, calculating the degree of each point in the Delaunay triangular mesh division result. The calculation method is to count the number of points connected with the current point. And if the number of the points connected with the current point is i, the degree of the current point is i.

Step 5.2 optionally selecting a point with an odd number as the current point, wherein the points connected with the current point form a set omega 1

And 5.3, judging whether points with odd numbers exist in the set omega 1, and if not, forming a set omega 2 by the points connected with the omega 1. A point in Ω 2 is judged, and if a point exists in both Ω 2 and Ω 1, the point is deleted in Ω 2.

And 5.4, judging whether points with odd numbers exist in the set omega 2, and if not, forming a set omega 3 by the points connected with the omega 2. A point in Ω 3 is judged, and if a point exists in Ω 1 or Ω 2, and also in Ω 3, the point is deleted in Ω 3.

Step 5.5, obtaining two or more point sets Ω 1, Ω 2.. Ω n with connection relations according to the method. Where there are odd numbered points in Ω n. One connection path a-B-C-. X from the current point to an odd-numbered point in Ω n is obtained from Ω 1, Ω 2.

Step 5.6, adding connecting lines in the Delaunay triangular mesh according to the connecting paths, and specifically comprising the following steps:

and 5.6.1, forming a current working line segment by the first point i and the second point j in the connecting path, finding a triangle containing the current working line segment in the Delaunay triangular mesh, and taking the triangle as the current working triangle.

Step 5.6.2 in the current working triangle, an inclusive hexagon is constructed. The method comprises the following specific steps:

step 5.6.2.1 constructs three line segments of a length inside the triangle that are parallel to and do not intersect three sides of the triangle.

Step 5.6.2.1 connects three line segments in a counterclockwise sequence to form a hexagon.

Step 5.6.3 finds a line segment in the hexagon that is parallel to and closest to the current working line segment as the added line segment. And connecting the end point of the current working line segment with the end point nearest to the adding line segment to form a parallelogram.

And 5.6.4, adding three line segments of the parallelogram except the current working line segment into the grid as newly added connecting lines.

Step 5.7: repeat 5.1-5.6 until all points in the grid are even in degree.

Further, the generation algorithm of the uninterrupted printing path is an Euler loop algorithm for solving an undirected graph. The Euler loop algorithm for solving the undirected graph is a Hierholzer algorithm.

Further, the starting point of the euler loop is chosen to satisfy the closest principle. The method comprises the following specific steps:

in the first layer, an optional point is used as the initial point of Euler path

At the next layer, the point closest to the initial point of the previous layer is selected as the initial point of the euler path for this layer.

Example (b): taking the model in fig. 1 as an example, the printing path algorithm is explained, and the specific steps include:

reading a model file;

setting the slice thickness to be 0.1mm to obtain the outer contour of the model to be printed on each layer, as shown in FIG. 2;

setting the density of random points to be 50, and generating uniform random points inside, as shown in FIG. 3;

defining the distance threshold value between the point and the point to be 1mm, deleting the point with the too close distance, and interpolating the point on the boundary point, as shown in FIG. 4;

performing Delaunay triangular mesh division on the existing point set, as shown in fig. 5;

the optimization algorithm for removing the grid lines is performed on the grid, as shown in fig. 6. Compared with the existing straight line filling algorithm, the straight line filling result is shown in fig. 7, the straight line row spacing and the distance threshold between the point and the point are set to be the same, and under the condition of the same distance, the filling rate of grid line filling is far greater than that of straight line filling.

In an embodiment, FIG. 8 shows that the total length of the grid-line-filled fill lines is 215.946 and the total length of the straight-line-filled fill lines is 120. The longer the total length of the filling line, the greater the filling rate and the greater the load-bearing capacity of the model.

FIG. 6 shows grid line filling, and FIG. 7 shows straight line filling, and comparing FIG. 6 with FIG. 7, it is known that when two filling models simultaneously bear bending moment in a direction perpendicular to the tangent plane, the grid filling has stronger capability of bearing bending moment than straight line filling. From a strength perspective, the load bearing capacity of the grid fill is greater than the load bearing capacity of the straight fill, whether it is tensile in the y-direction, bending in the x-direction, or bending in the z-direction.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.