A single-path 3D printing path planning method and system

Abstract

The present invention discloses a single-pass 3D printing path planning method and system. Considering the continuity of continuous fibers, the proposed method generates a single-pass path that can be printed continuously without cutting each layer of fibers. The method adopts the idea of ​​discrete mathematics to discretize a filling model or a path tracing graph into a connected graph formed by connecting points and lines; based on the connected graph, it is determined whether it is an Euler graph or a semi-Eulerian graph, which can be used as a basis for generating path planning; the solution to the Chinese postal route problem is used to find the Euler path in the connected graph and select the optimal solution; the gap value between the path and the original path is increased by changing the method parameters; the printing path is linked in sequence according to the Euler path to generate a printing code; the present invention is applied to various geometric shapes of filling patterns to meet the requirements of 3D printing technology.

Description

Technical Field

[0001] The present invention belongs to the technical field of filling path planning, and in particular relates to a single-path 3D printing path planning method and system. Background Art

[0002] 3D printing technology has the advantages of high efficiency, rapidity and free molding, and has been applied to a certain extent in the fields of biomedicine, industrial manufacturing, construction engineering, and aerospace. However, since traditional 3D printing technology uses gypsum, thermoplastic resin, inorganic powder, etc. as printing materials, the molded parts cannot fully meet the use requirements in the industrial field in terms of stiffness, strength and application performance, which limits the development of 3D printing in the industrial field.

[0003] 3D printers using continuous fiber composites as materials have attracted great research interest worldwide due to their higher mechanical properties compared to other 3D printing materials. In particular, previous studies have shown that continuous carbon fiber composites have great potential as 3D printing materials. The traditional method of using continuous fiber composites as 3D printer materials is to manufacture filaments as intermediate materials and directly impregnate resin onto the fibers in the nozzle during the printing process.

[0004] The characteristics of FDM 3D printers that use only resin or short fibers are very different from those of 3D printers that use continuous fibers as materials. The premise for ensuring the performance of continuous fiber composite materials is to ensure the continuity of the fibers. Path planning for FDM printing processes includes: grid contour filling, contour offset path filling, mixed path filling and other methods cannot be used normally. It is difficult to solve this problem using the current slicing method in the continuous fiber printing process. Fiber cutting is required at the jumping points, and material accumulation will occur at the intersections, causing fiber damage. However, depending on the desired pattern selected, multiple cuts may be required. Cutting the fibers means that there is a discontinuity in the fiber bundle at that point. At these points, the strength is expected to be much lower than that of continuous fibers, which will affect the performance of the structure. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a single-pass 3D printing path planning method and system for solving the technical problem of continuous fiber 3D printing path planning in view of the deficiencies in the above-mentioned prior art.

[0006] The present invention adopts the following technical solutions:

[0007] A single-pass 3D printing path planning method comprises the following steps:

[0008] S1. Determine the printing model, confirm the types of continuous fibers and printing substrates according to the target component requirements, obtain corresponding process parameters, and generate a plane model;

[0009] S2. Based on the idea of ​​discrete mathematics, the plane model obtained in step S1 is discretized into a connected graph connected by points and lines. Based on the connected graph, an Euler graph or a semi-Euler graph is used as the basis for generating path planning;

[0010] S3, planning a printing path according to the Euler diagram or semi-Eulerian diagram obtained in step S2;

[0011] S4, adjusting the gap between the original printed path and the added path according to the printing path obtained in step S3, to complete the path compensation;

[0012] S5. According to the sequence of the Euler path, the coordinate points on the printing path after the path compensation in step S4 are extracted, and a printing program is generated to realize layer-by-layer printing.

[0013] Specifically, in step S1, when the obtained printing model is a filling model, a printing outline is generated, and a pattern is selected to fill the inside of the outline to generate a plane model. When the obtained printing model is a path tracing model, a plane model is directly generated.

[0014] Specifically, in step S1, the target component is a two-dimensional structure.

[0015] Specifically, in step S2, when it is not an Euler graph or a semi-Eulerian graph, paths are added to the edges of the connected graph to give a connected graph, and the optimal solution is found based on the shortest path required to pass through each edge at least once.

[0016] Furthermore, the path generation is specifically as follows:

[0017] Using the FLOYD method, the length of the shortest path between any two points in the connected graph is calculated. After selecting the starting point and the end point, the optimal solution for path increase is found according to the 0-1 programming model.

[0018] Furthermore, the 0-1 planning model is specifically as follows:

[0019]

[0020]

[0021] Among them, z is the length of the path to be increased, x ij is a point V with an odd degree i and V j The pairing relationship, l ij V is an odd number. i and V j distance.

[0022] Specifically, in step S3, the circular arc and the elliptical arc in the Euler diagram or the semi-Euler diagram are compensated as follows:

[0023] The coordinates of the center point, starting angle, and ending angle of the arc or elliptical arc are read, and the values ​​are calculated at fixed angle intervals in the form of a parametric equation. The arc curve is differentiated into line segments. The line segments obtained by differentiating the arc curve in the connected graph are not used as reference edges for adding paths.

[0024] Furthermore, the starting angle and the ending angle of the arc curve are calculated counterclockwise. When the value needs to be taken clockwise, the starting angle and the ending angle need to be interchanged, and the fixed division degree needs to be negative.

[0025] Specifically, in step S4, the gap between the original printed path and the added path is adjusted as follows:

[0026] After the Euler path is generated, the added path is adjusted accordingly. The added path and the original path are adjusted accordingly to form two paths that are symmetrical to the original path. The coordinates of the four vertices are automatically calculated according to the gap distance and the normal direction of the original path, and the four vertices are connected in sequence to generate a continuous and uninterrupted printing path.

[0027] In a second aspect, an embodiment of the present invention provides a single-pass 3D printing path planning system, comprising:

[0028] The generation module determines the printing model, confirms the types of continuous fibers and printing substrates according to the requirements of the target components, obtains the corresponding process parameters, and generates a plane model;

[0029] The discrete module, based on the idea of ​​discrete mathematics, discretizes the plane model obtained by the generation module into a connected graph connected by points and lines. Based on the connected graph, the Euler graph or semi-Euler graph is used as the basis for generating path planning;

[0030] A planning module plans a printing path according to the Euler diagram or semi-Eulerian diagram obtained by the discrete module;

[0031] The compensation module adjusts the gap between the original printed path and the added path according to the printing path obtained by the planning module to complete the path compensation;

[0032] The printing module extracts the coordinate points on the printing path after the compensation module path compensation according to the order of the Euler path, and generates a printing program to realize layer-by-layer printing.

[0033] Compared with the prior art, the present invention has at least the following beneficial effects:

[0034] The present invention discloses a single-distance 3D printing path planning method, which adopts the idea of ​​discrete mathematics to discretize a filling model or a path tracing graph into a connected graph formed by connecting points and lines; based on the connected graph, it is determined whether it is an Euler graph or a semi-Eulerian graph, which can be used as a basis for generating path planning; the solution to the Chinese postal route problem is adopted to find the Euler path in the connected graph and select the optimal solution; the gap value between the path and the original path is increased by changing the algorithm parameters; the printing path is sequentially linked according to the Euler path to generate a printing code; the present invention is applied to the geometric shapes of various filling patterns to meet the 3D printing process requirements.

[0035] Furthermore, when the obtained printing model is a filling model, a printing outline is generated, and a pattern is selected to fill the inside of the outline to generate a plane model. When the obtained printing model is a path tracing model, a plane model is directly generated. During the printing process, the printing of the target specimen is performed by gradually raising the plane model to a three-dimensional model. Generating a plane model helps to identify the basic structure of the event.

[0036] Furthermore, the target component is a two-dimensional structure, and the target specimen targeted by the present invention is a complex planar two-dimensional structure. Accurately identifying the two-dimensional structure of the planar model is a prerequisite for completing path planning.

[0037] Furthermore, when it is not an Euler graph or a semi-Eulerian graph, paths are added to the edges of the connected graph to give a connected graph. The optimal solution is found based on the shortest path required to pass through each edge at least once. The core idea of ​​the present invention is to find the shortest distance to complete the path of the connected graph based on the Chinese postal route problem.

[0038] Furthermore, by finding the length of the shortest path between any two points in the connected graph, after traversing all the nodes, we will know the shortest distance between any two points.

[0039] Furthermore, the purpose of setting up the 0-1 planning model is that the reason why there is no Euler path in the connected graph is that the number of points with odd degrees is not 0 or 2. To solve this problem, we need to increase the path between two odd nodes and make the odd nodes become even nodes, and finally satisfy the existence of Euler path.

[0040] Furthermore, for circular arcs and elliptical arcs in Euler diagrams or semi-Euler diagrams, when performing two-dimensional structural feature recognition, it is necessary to discretize the circular arcs into multiple line segments based on the discrete idea for compensation. The specific method is to use parametric equations, calculate values ​​at fixed angles, and differentiate the arc curve into line segments.

[0041] Furthermore, according to the different clockwise and counterclockwise orientations of the arc curve and the rotation angles of the elliptical arc, the method can automatically adjust the form of the parametric equation. The starting angle and the ending angle of the arc curve are often calculated counterclockwise. When the clockwise value is required, the starting angle and the ending angle need to be interchanged, and the fixed division degree is negative.

[0042] Furthermore, the gap between the original printing path and the added path is adjusted according to different printing materials and printing parameter settings to meet the needs of multi-material printing.

[0043] It can be understood that the beneficial effects of the second aspect mentioned above can be found in the relevant description of the first aspect mentioned above, and will not be repeated here.

[0044] In summary, the present invention optimizes the printing effect of continuous fiber composite materials by printing in a single-stroke path planning manner. Taking the solution to the Chinese postal route problem as the core of the algorithm, the concepts of Euler diagram and semi-Euler diagram are introduced, and the Euler path is found through the FLOYD algorithm and the 0-1 planning model, which avoids jump points in the printing process and the problem of structural performance degradation caused by fiber cutting, greatly improving the effect of continuous fiber printing. The efficiency of printing complex structures is also improved by discretizing the connected graph after pattern filling and differentiating the arc curve. The final printing path can give full play to the performance advantages of the structure and meet the requirements of the printing process.

[0045] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 A flow chart for planning a single-path 3D printing path;

[0047] Figure 2 Floor plans generated for populating models;

[0048] Figure 3 Added optimal solution for filling model path;

[0049] Figure 4 This is a schematic diagram of path adjustment and compensation;

[0050] Figure 5 Print physical images for filling models;

[0051] Figure 6 Floor plans generated for the tracing model;

[0052] Figure 7 Add optimal solution diagram for tracking path;

[0053] Figure 8 Schematic diagram of arc curve optimization compensation;

[0054] Fig. 9 Print physical drawings for tracing models. DETAILED DESCRIPTION

[0055] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0056] In the description of the present invention, it should be understood that the terms “include” and “comprises” indicate the presence of described features, wholes, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or collections thereof.

[0057] It should also be understood that the terms used in the present specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0058] It should be further understood that the term "and / or" used in the present specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes these combinations. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects are in an "or" relationship.

[0059] It should be understood that, although the terms first, second, third, etc. may be used to describe preset ranges, etc. in the embodiments of the present invention, these preset ranges should not be limited to these terms. These terms are only used to distinguish preset ranges from each other. For example, without departing from the scope of the embodiments of the present invention, the first preset range may also be referred to as the second preset range, and similarly, the second preset range may also be referred to as the first preset range.

[0060] The word "if" as used herein may be interpreted as "at the time of" or "when" or "in response to determining" or "in response to detecting", depending on the context. Similarly, the phrases "if it is determined" or "if (stated condition or event) is detected" may be interpreted as "when it is determined" or "in response to determining" or "when detecting (stated condition or event)" or "in response to detecting (stated condition or event)", depending on the context.

[0061] Various structural schematic diagrams of the embodiments disclosed in the present invention are shown in the accompanying drawings. These figures are not drawn to scale, and some details are magnified and some details may be omitted for the purpose of clear expression. The shapes of various regions and layers shown in the figures and the relative sizes and positional relationships therebetween are only exemplary, and may deviate in practice due to manufacturing tolerances or technical limitations, and those skilled in the art may additionally design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0062] The present invention provides a single-pass 3D printing path planning method. Considering the continuity of continuous fibers, the FDM printing method is used as the basis, and continuous fibers are used as the reinforcing material to generate a single-pass printing path. The fibers remain continuous throughout the process, there are no breakpoints, and there is no need to cut the fibers. The core of the present invention is to combine the printing path planning problem with the Chinese postal route problem, calculate the optimal solution for path planning by adding paths, adjusting gaps, compensating distances, optimizing arcs, etc., and finally generate printing codes according to the sequence to meet the printing process requirements.

[0063] See also Figure 1 The present invention provides a single-path 3D printing path planning method, comprising the following steps:

[0064] S1. Determine whether the model to be printed is a filling model or a path tracking model, confirm the types of continuous fibers and printing substrates according to the requirements of the target component, and then determine the matching process parameters, including printing temperature, printing speed, substrate temperature, interlayer thickness, path spacing, etc.;

[0065] The printing target component is a two-dimensional structure, and the printing parameters are adjusted according to the size of the material and the printing nozzle.

[0066] If it is a filled model, use computer-aided design (CAD) to further generate a print outline, select an appropriate pattern to fill the inside of the outline, the type and size of the pattern determines the filling density inside the structure, and then generate a plane model. If it is a path tracing model, the plane model can be directly generated;

[0067] S2. Using the idea of ​​discrete mathematics, the filled plane model is discretized into a connected graph connected by points and lines. Based on the connected graph, it is judged whether it is an Euler graph or a semi-Euler graph. The Euler graph or semi-Euler graph is used as the basis for generating path planning. If not, paths are added to some edges of the connected graph to meet the conditions. The method of adding paths is based on the Chinese postal route problem (given a connected graph, the shortest path required to pass through each edge at least once) to find the optimal solution.

[0068] The method of path generation is combined with the Chinese Postman Problem. The core of the method of generating an Euler graph using the solution of the Chinese Postman Problem lies in: First, using the FLOYD method, find the length of the shortest path between any two points in the connected graph. After selecting the starting point and the ending point, find the optimal solution for path addition according to the 0-1 programming model.

[0069] There are two cases for calculating the shortest path length between any two points in a connected graph:

[0070] One is directly from i to j;

[0071] The other is from i through several nodes k to j.

[0072] Let Dis(i, j) be the distance of the shortest path from node i to node j. For each node k, check whether Dis(i, k) + Dis(k, j) < Dis(i, j) holds. If it holds, it proves that the path from i to k and then to j is shorter than the path from i directly to j. Set Dis(i, j) = Dis(i, k) + Dis(k, j). In this way, when all nodes k are traversed, the distance of the shortest path from i to j recorded in Dis(i, j) is obtained. After that, the shortest distance between any two points is known.

[0073] The reason why a connected graph does not have an Euler path is that the number of points with odd degrees is not 0 or 2. To solve this problem, paths are added between two odd nodes to make the odd nodes become even nodes, ultimately meeting the existence condition of the Euler path.

[0074] Next, the starting point and the ending point need to be selected. After selecting the starting point and the ending point, find the optimal solution for path addition according to the 0-1 programming model.

[0075] The core of the 0-1 model is as follows:

[0076] Let all points with odd degrees be V1, V2, ……, V n , where n is even. Let the variable x ij represent the pairing relationship between V i and V j as follows:

[0077]

[0078] Then there are:

[0079]

[0080]

[0081] Equation 2 is the objective function, indicating that the length of the added path in the connected graph is the smallest. Equations 3, 4, and 5 indicate that any fixed point can only have a matching relationship with one other fixed point.

[0082] S3. Plan the printing path according to the generated Euler diagram or semi-Euler diagram, and there will be targeted compensation methods for the circular arcs and elliptical arcs in the diagram;

[0083] The specific method of targeted compensation for the circular arc and elliptical arc in the figure is: first read the coordinates of the center point, starting angle, ending angle and other information of the circular arc or elliptical arc, calculate the value at fixed angle intervals in the form of parametric equations, and differentiate the arc curve into line segments.

[0084] The arc parameter equation is as follows:

[0085]

[0086] The parametric equation of the ellipse is as follows:

[0087]

[0088] Among them, x0 and y0 are the centers of the circle, r is the radius, θ0 is the starting angle, θ1 is the ending angle, x0 and y0 are the centers of the ellipse, a is the length of the major axis, b is the length of the minor axis, t is the inclination angle of the arc, θ0 is the starting angle, and θ1 is the ending angle.

[0089] The line segments derived from the differentiation of arc curves in the connected graph are not used as reference edges for adding paths.

[0090] According to the different clockwise and counterclockwise orientations of the arc curve and the rotation angles of the elliptical arc, this method can automatically adjust the form of the parametric equation. The starting angle and ending angle of the arc curve are often calculated counterclockwise. When clockwise values ​​are required, the starting angle and ending angle need to be swapped and the fixed division degree needs to be negative.

[0091] S4. Adjust the gap between the original printed path and the added path according to the printing path. This is closely related to the selection of continuous fiber filaments. In addition, the printing path needs to be compensated because the printing path control is deteriorated due to the fiber bending stiffness and the moment of inertia.

[0092] The added path will be adjusted accordingly to the original path to form two symmetrical paths of the original path. The coordinates of the four vertices will be automatically calculated according to the gap distance and the discovery direction of the original path, and the four vertices will be connected in sequence to generate a continuous and uninterrupted printing path.

[0093] The bending stiffness and moment of inertia of the fiber can cause the print path to deteriorate, which occurs when the added path is in tandem with the original path.

[0094] S5. According to the order of the Euler path, the coordinate points on the path are extracted, a printing program is generated, and printing is performed layer by layer.

[0095] In another embodiment of the present invention, a single-pass 3D printing path planning system is provided, which can be used to implement the above-mentioned single-pass 3D printing path planning method. Specifically, the single-pass 3D printing path planning system includes a generation module, a discrete module, a planning module, a compensation module and a printing module.

[0096] Among them, the generation module determines the printing model, confirms the types of continuous fibers and printing substrates according to the requirements of the target component, obtains the corresponding process parameters, and generates a plane model;

[0097] The discrete module, based on the idea of ​​discrete mathematics, discretizes the plane model obtained by the generation module into a connected graph connected by points and lines. Based on the connected graph, the Euler graph or semi-Euler graph is used as the basis for generating path planning;

[0098] A planning module plans a printing path according to the Euler diagram or semi-Eulerian diagram obtained by the discrete module;

[0099] The compensation module adjusts the gap between the original printed path and the added path according to the printing path obtained by the planning module to complete the path compensation;

[0100] The printing module extracts the coordinate points on the printing path after the compensation module path compensation according to the order of the Euler path, and generates a printing program to realize layer-by-layer printing.

[0101] In another embodiment of the present invention, a terminal device is provided, the terminal device includes a processor and a memory, the memory is used to store a computer program, the computer program includes program instructions, and the processor is used to execute the program instructions stored in the computer storage medium. The processor may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components, etc., which are the computing core and control core of the terminal, which are suitable for implementing one or more instructions, and are specifically suitable for loading and executing one or more instructions to implement corresponding method processes or corresponding functions; the processor described in the embodiment of the present invention can be used for the operation of a single-pass 3D printing path planning method, including:

[0102] Determine the printing model, confirm the types of continuous fibers and printing substrates according to the requirements of the target component, obtain the corresponding process parameters, and generate a plane model; based on the idea of ​​discrete mathematics, discretize the plane model into a connected graph connected by points and lines, and use the Euler graph or semi-Euler graph as the basis for generating path planning based on the connected graph; plan the printing path according to the Euler graph or semi-Euler graph; adjust the gap between the original printed path and the added path according to the printing path to complete the path compensation; according to the order of the Euler path, extract the coordinate points on the printing path after path compensation, and generate a printing program to realize layer-by-layer printing.

[0103] In another embodiment of the present invention, the present invention further provides a storage medium, specifically a computer-readable storage medium (Memory), which is a memory device in a terminal device for storing programs and data. It can be understood that the computer-readable storage medium here can include both the built-in storage medium in the terminal device and the extended storage medium supported by the terminal device. The computer-readable storage medium provides a storage space, which stores the operating system of the terminal. In addition, one or more instructions suitable for being loaded and executed by the processor are also stored in the storage space, and these instructions can be one or more computer programs (including program codes). It should be noted that the computer-readable storage medium here can be a high-speed RAM memory, or a non-volatile memory (Non-Volatile Memory), such as at least one disk memory.

[0104] The processor may load and execute one or more instructions stored in a computer-readable storage medium to implement the corresponding steps of the single-pass 3D printing path planning method in the above embodiment; the processor may load and execute the following steps:

[0105] Determine the printing model, confirm the types of continuous fibers and printing substrates according to the requirements of the target component, obtain the corresponding process parameters, and generate a plane model; based on the idea of ​​discrete mathematics, discretize the plane model into a connected graph connected by points and lines, and use the Euler graph or semi-Euler graph as the basis for generating path planning based on the connected graph; plan the printing path according to the Euler graph or semi-Euler graph; adjust the gap between the original printed path and the added path according to the printing path to complete the path compensation; according to the order of the Euler path, extract the coordinate points on the printing path after path compensation, and generate a printing program to realize layer-by-layer printing.

[0106] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. The components of the embodiments of the present invention described and shown in the drawings here can usually be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0107] Example 1

[0108] This embodiment provides a path planning method for a continuous fiber composite material filling model, comprising the following steps:

[0109] 1) In this embodiment, 1K continuous fiber bundles and PLA resin are used as raw materials to perform 3D printing of continuous fiber composite materials.

[0110] According to the material properties, the process parameters are selected as follows: printing temperature 205°C, printing speed 10 mm / s, substrate temperature 50°C, interlayer thickness 0.25 mm, path spacing 0.6 mm, nozzle diameter 1 mm, and compensation length 1 mm.

[0111] 2) Determine the printing outline as a rectangular area of ​​150mm×100mm, fill the pattern and generate a plane model as follows Figure 2 Shown

[0112] 3) Using the idea of ​​discrete mathematics Figure 2 The plane model shown is discretized into a connected graph connected by points and lines (the connected graph is an undirected graph at this time), and then judge whether the plane model is an Euler graph or a semi-Eulerian graph. According to the Euler graph judgment theorem: an undirected connected graph G contains an Euler path if and only if G has zero or two nodes of odd degree. Obviously, the number of odd nodes in this graph is greater than two, indicating that there is no Euler path in this connected graph.

[0113] 4) First, calculate the minimum distance between each odd-numbered node according to the FLOYD method mentioned above. After selecting the starting point and the end point, find the optimal solution for path increase according to the 0-1 planning model. Figure 3 shown.

[0114] 5) According to the Euler path generated in 4), it can be seen that the added path is not simply offset, but adjusted accordingly to form two paths symmetrical to the original path. Figure 4 As shown in a, assume that the coordinates of point A are (xa ,y a ), the coordinates of point B are (x b ,y b ), add the vertices of the path to A1, A2, B1, B2. First calculate the angle α between A and B:

[0115]

[0116] Assuming the path spacing is d, the coordinates of A1 (x1, y1) can be obtained by the following formula

[0117]

[0118] Similarly, find the coordinates of points A2, B1, B2, etc.

[0119] 6) For some special cases, print paths A1, B1, B2, A2, such as Figure 4 As shown in b, the added path and the original path are sequential paths, and the fiber bending stiffness and moment of inertia will cause the printing path control to deteriorate, and printing path compensation is required. The compensation method is to increase the end point of the line segment along the printing direction by a certain distance. At this time, B1, B2, become B m , B n , calculate the coordinates of B1 (x3, y3) according to 5), and calculate the compensated B according to the following calculation formula m The coordinate value x m ,y m :

[0120]

[0121] Where l is the increased distance.

[0122] Similarly, find B n The coordinates of the point.

[0123] 7) By repeating steps 5) and 6), we can find Figure 3 All points after adjustment and compensation.

[0124] 8) After one layer of printing is completed, the Z axis increases by 0.25mm. At this time, the starting and ending points of the previous layer are replaced, and the process is repeated along the original path to complete the printing. Figure 5 shown.

[0125] Example 2

[0126] This embodiment provides a path planning method for a continuous fiber composite material path tracking model, comprising the following steps:

[0127] 1) This embodiment uses 1K continuous fiber bundles and TPU resin as raw materials to perform 3D printing of continuous fiber composite materials. According to the material properties, the process parameters are selected as follows: printing temperature 230°C, printing speed 10mm / s, substrate temperature 65°C, interlayer thickness 0.25mm, path spacing 0.6mm, nozzle diameter 1mm, and compensation length 1mm.

[0128] 2) This embodiment is different from the filling model. All curves in the model file can be directly read and a plane model can be generated. Figure 6 Shown

[0129] 3) Similar to the plane filling model, the idea of ​​discrete mathematics is used to Figure 6 The plane model shown is discretized into a connected graph connected by points and lines (the connected graph is an undirected graph at this time), and then judge whether the plane model is an Euler graph or a semi-Eulerian graph. According to the Euler graph judgment theorem: an undirected connected graph G contains an Euler path if and only if G has zero or two nodes of odd degree. Obviously, the number of odd nodes in this graph is greater than two, indicating that there is no Euler path in this connected graph.

[0130] 4) First, calculate the minimum distance between each odd-numbered node according to the FLOYD method mentioned above. After selecting the starting point and the end point, find the optimal solution for path increase according to the 0-1 planning model. Figure 7 shown.

[0131] 5) The same method as in Example 1 is adopted for adjusting the added path and compensating the printing path. The method is described in detail as follows: Figure 8 Shown

[0132] 6) For the case where the arc curves in the model include elliptical arcs, circular arcs, etc., the invented method is set, in order to reduce the amount of calculation, the arc curve is not in the direction of the path increase, and the specific method of the targeted compensation method is: first read the coordinates of the center point of the circular arc or elliptical arc, the starting angle, the ending angle and other information, calculate the value at fixed angle intervals in the form of a parametric equation, connect the points in sequence, and differentiate the arc curve into line segments. The parametric equation is as follows:

[0133]

[0134]

[0135] Formula 11 is the arc parameter equation, x0 and y0 are the center of the circle, r is the radius, θ0 is the starting angle, and θ1 is the ending angle. Formula 12 is the ellipse parameter equation, x0 and y0 are the ellipse center, a is the major axis length, b is the minor axis length, t is the arc inclination angle, θ0 is the starting angle, and θ1 is the ending angle. The specific calculation method is as follows: Figure 8As shown in the figure, taking the ellipse arc as an example, read the center coordinates O(x0,y0) of the ellipse and the coordinates of the major axis endpoints T(x t ,y t ), the inclination angle t can be calculated as follows:

[0136]

[0137] The arc curve also needs to be adjusted for different printing directions. Figure 8 a and Figure 8 As shown in b, by default, the arc is printed in a counterclockwise direction, which is consistent with the mathematical calculation method. Figure 8 a, no changes are needed at this time, but for the clockwise situation, changes need to be made. In order to make the printing go smoothly, the original starting angle and ending angle need to be swapped as follows Figure 8 b. In addition, because the starting angle is greater than the ending angle, the differential method is also changed from the previous angle increasing value to the angle decreasing value. The arc situation is the same as the ellipse principle.

[0138] 7) By repeating steps 5) and 6), we can find Figure 7 All points after adjustment and compensation.

[0139] 8) After one layer of printing is completed, the Z axis increases by 0.25mm. At this time, the starting and ending points of the previous layer are replaced, and the process is repeated along the original path to complete the printing. Fig. 9 shown.

[0140] In summary, the present invention provides a single-pass 3D printing path planning method and system, which optimizes the printing effect of continuous fiber composite materials by means of single-pass path planning printing. Taking the solution to the Chinese postal route problem as the core of the method, the concepts of Euler diagram and semi-Euler diagram are introduced, and the Euler path is found through the FLOYD method and the 0-1 planning model, thereby avoiding the jump points in the printing process, thus avoiding the problem of structural performance degradation caused by fiber cutting, and greatly improving the effect of continuous fiber printing. The efficiency of printing complex structures is also improved by discretizing the connected graph after pattern filling and differentiating the arc curve. The final printing path can give full play to the performance advantages of the structure and meet the requirements of the printing process.

[0141] The technicians in the relevant field can clearly understand that for the convenience and simplicity of description, only the division of the above-mentioned functional units and modules is used as an example for illustration. In practical applications, the above-mentioned function allocation can be completed by different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiment can be integrated in a processing unit, or each unit can exist physically separately, or two or more units can be integrated in one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of software functional units. In addition, the specific names of the functional units and modules are only for the convenience of distinguishing each other, and are not used to limit the scope of protection of this application. The specific working process of the units and modules in the above-mentioned system can refer to the corresponding process in the aforementioned method embodiment, which will not be repeated here.

[0142] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0143] Those of ordinary skill in the art will appreciate that the units and method steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0144] In the embodiments provided by the present invention, it should be understood that the disclosed devices / terminals and methods can be implemented in other ways. For example, the device / terminal embodiments described above are only schematic. For example, the division of the modules or units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0145] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0146] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0147] If the integrated module / unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the present invention implements all or part of the processes in the above-mentioned embodiment method, and can also be completed by instructing the relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium, and the computer program can implement the steps of the above-mentioned various method embodiments when executed by the processor. Among them, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form. The computer-readable medium may include: any entity or device capable of carrying the computer program code, recording medium, U disk, mobile hard disk, disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electric carrier signal, telecommunication signal and software distribution medium, etc. It should be noted that the content contained in the computer-readable medium can be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, computer-readable media do not include electric carrier signals and telecommunication signals.

[0148] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0149] These computer program instructions may also be stored in a computer readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture including an instruction device, which implements the process Figure 1A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0150] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0151] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A single-path 3D printing path planning method, characterized in that: The following steps are involved: S1. Determine the printing model, confirm the types of continuous fibers and printing substrates according to the target component requirements, obtain corresponding process parameters, and generate a plane model; S2. Based on the idea of ​​discrete mathematics, the plane model obtained in step S1 is discretized into a connected graph connected by points and lines. Based on the connected graph, the Euler graph or semi-Euler graph is used as the basis for generating path planning. When it is not an Euler graph or a semi-Euler graph, a path is added to the edge of the connected graph to give a connected graph. Based on the shortest path required to pass through each edge at least once, the optimal solution is found. The path generation is specifically as follows: Using the FLOYD method, find the length of the shortest path between any two points in the connected graph. After selecting the starting point and the end point, find the optimal solution for path increase according to the 0~1 programming model. S3, planning a printing path according to the Euler diagram or semi-Eulerian diagram obtained in step S2; S4, adjusting the gap between the original printed path and the added path according to the printing path obtained in step S3, to complete the path compensation; S5. According to the sequence of the Euler path, the coordinate points on the printing path after the path compensation in step S4 are extracted, and a printing program is generated to realize layer-by-layer printing.

2. The single-pass 3D printing path planning method according to claim 1, characterized in that: In step S1, when the obtained printing model is a filling model, a printing outline is generated, and a pattern is selected to fill the inside of the outline to generate a plane model. When the obtained printing model is a path tracing model, a plane model is directly generated.

3. The single-pass 3D printing path planning method according to claim 1, characterized in that: In step S1, the target component is a two-dimensional structure.

4. The single-pass 3D printing path planning method according to claim 1, characterized in that: In step S2, the 0~1 planning model is specifically: in, To increase the length of the path, is a point with an odd degree and The pairing relationship, Odd number of points and distance.

5. The single-pass 3D printing path planning method according to claim 1, characterized in that: In step S3, the circular arc and the elliptical arc in the Euler diagram or the semi-Euler diagram are compensated as follows: The coordinates of the center point, starting angle, and ending angle of the arc or elliptical arc are read, and the values ​​are calculated at fixed angle intervals in the form of a parametric equation. The arc curve is differentiated into line segments. The line segments obtained by differentiating the arc curve in the connected graph are not used as reference edges for adding paths.

6. The single-pass 3D printing path planning method according to claim 5, characterized in that: The starting angle and ending angle of the arc curve are calculated counterclockwise. When the value needs to be taken clockwise, the starting angle and the ending angle need to be swapped and the fixed division degree needs to be negative.

7. The single-pass 3D printing path planning method according to claim 1, characterized in that: In step S4, the gap between the original printed path and the added path is adjusted as follows: After the Euler path is generated, the added path is adjusted accordingly. The added path and the original path are adjusted accordingly to form two paths that are symmetrical to the original path. The coordinates of the four vertices are automatically calculated according to the gap distance and the normal direction of the original path. The four vertices are connected in sequence to generate a continuous and uninterrupted printing path.

8. A single-pass 3D printing path planning system, characterized in that: include: The generation module determines the printing model, confirms the types of continuous fibers and printing substrates according to the requirements of the target components, obtains the corresponding process parameters, and generates a plane model; The discrete module, based on the idea of ​​discrete mathematics, discretizes the plane model obtained by the generation module into a connected graph connected by points and lines. Based on the connected graph, the Euler graph or semi-Eulerian graph is used as the basis for generating path planning. When it is not an Euler graph or a semi-Eulerian graph, a path is added to the edge of the connected graph to give a connected graph. Based on the shortest path required to pass through each edge at least once, the optimal solution is found. The path generation is specifically as follows: Using the FLOYD method, find the length of the shortest path between any two points in the connected graph. After selecting the starting point and the end point, find the optimal solution for path increase according to the 0~1 programming model. A planning module plans a printing path according to the Euler diagram or semi-Eulerian diagram obtained by the discrete module; The compensation module adjusts the gap between the original printed path and the added path according to the printing path obtained by the planning module to complete the path compensation; The printing module extracts the coordinate points on the printing path after the compensation module path compensation according to the order of the Euler path, and generates a printing program to realize layer-by-layer printing.

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