Method and device for generating a three-dimensional printing path for a curved surface

Abstract

The application discloses a kind of surface-oriented three-dimensional printing path generation method and device, wherein the method includes: selecting the boundary of grid surface as initial path;Current path is recorded as initial path and path offset cycle operation is carried out, and finally three-dimensional printing path is formed based on all offset paths, and path offset is as follows: construct reference plane with the tangent direction of current path point and the tangent direction of current path as normal vector direction;Determine the intersection line section of reference plane and grid surface in reference plane;Two overlapping areas of the drum-shaped section created based on the two end points of intersection line section and the drum-shaped section created based on current path point are calculated respectively;If target overlapping area is between two overlapping areas, offset path point is determined on intersection line section by bisection method iteratively;Offset path point corresponding to each path point is connected, and the offset path of current path is obtained.The application can improve the manufacturing precision of three-dimensional printing surface.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of three-dimensional printing, in particular to a curved surface-oriented three-dimensional printing path generation method and device. BACKGROUND

[0002] Traditional three-dimensional printing is a manufacturing technology based on layer-by-layer printing and gradual accumulation of materials, which brings good manufacturing process stability and simplifies the manufacturing principle, but also makes the printed parts have obvious step effect, which has a negative impact on the surface quality and mechanical properties of the manufactured products. Curved surface three-dimensional printing is an advanced technology of traditional three-dimensional printing, which is mainly used for high-precision forming of objects with complex curved surface structures (such as free curved surfaces, irregular curved surfaces, etc.).

[0003] However, in the existing curved surface three-dimensional printing process, the part is only decomposed into relatively simple voxels, the forming direction of the manufacturing curved surface is adjusted, and the traditional plane slicing technology is still used to obtain the layered contour for plane contour filling and path connection, which does not change the characteristics of plane layered forming in essence, resulting in the printed finished product still having the defect of low quality and performance. The concept of equal residual height is proposed in the existing curved surface three-dimensional printing process, but it cannot meet the manufacturing requirements of curved surfaces with large curvature, resulting in poor precision, roughness, quality and mechanical properties of the final printed product. SUMMARY

[0004] The embodiment of the present application provides a curved surface-oriented three-dimensional printing path generation method to improve the manufacturing precision of curved surfaces, reduce roughness, and improve the manufacturing quality and mechanical properties of curved surfaces. The method comprises the following steps:

[0005] Constructing a grid curved surface based on a to-be-printed curved surface model;

[0006] Selecting the boundary of the grid curved surface as an initial path; the initial path comprises a plurality of path points;

[0007] Recording the initial path as a current path, and performing the following loop operation steps 1 to 3 on the current path until a plurality of offset paths are obtained:

[0008] Step 1: performing the following operation steps 1.1 to 1.4 on each path point on the current path until an offset path point corresponding to each path point is obtained:

[0009] Step 1.1: constructing a reference plane passing through the current path point and having a tangent direction of the current path as a normal direction;

[0010] Step 1.2: determining a intersection line segment of the reference plane and the grid curved surface in the reference plane;

[0011] Step 1.3: Calculate the first and second overlap areas of the drum-shaped cross-section created based on the two endpoints of the intersecting line segment and the drum-shaped cross-section created based on the current path point; the drum-shaped cross-section is the cross-sectional shape of the 3D printed extruded filament.

[0012] Step 1.4: If the pre-set target overlap area is between the first overlap area and the second overlap area, the offset path point corresponding to the current path point is determined iteratively on the intersection line segment using the bisection method; wherein the third overlap area of ​​the drum-shaped cross section created based on the offset path point and the drum-shaped cross section created based on the current path point meets the preset difference requirement with the target overlap area.

[0013] Step 2: Connect the offset path points corresponding to each path point on the current path to obtain the offset path of the current path;

[0014] Step 3: Update the bias path to the current path;

[0015] Connect all offset paths end-to-end at adjacent positions to obtain the 3D printing path.

[0016] This invention also provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the above-described method for generating three-dimensional printing paths for curved surfaces.

[0017] This invention also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the above-described method for generating 3D printing paths for curved surfaces.

[0018] This invention also provides a computer program product, which includes a computer program that, when executed by a processor, implements the above-described method for generating 3D printing paths for curved surfaces.

[0019] This invention proposes a direct offset basis for generating paths on 3D printed curved surfaces. If the pre-set target overlap area is between the first and second overlap areas, the offset path point corresponding to the current path point is determined iteratively on the intersection line segment using a bisection method. The third overlap area of ​​the drum-shaped cross section created based on the offset path point and the drum-shaped cross section created based on the current path point meets the preset difference requirement with the target overlap area, i.e., equal overlap area offset basis. This method assumes that when the overlap area is equal to the pre-set target overlap area, the material cladding can achieve uniform filling without under- or over-stacking. This invention can directly control the density of the cladding material in 3D printed curved surfaces while ensuring its uniform stacking, thereby reducing the surface roughness and improving the mechanical properties and quality of the manufactured curved surfaces. Attached Figure Description

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description only constitute some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained from these drawings without creative labor. In the drawings:

[0021] Figure 1 A flowchart of the method for generating a three-dimensional printing path facing a curved surface in the embodiments of the present application;

[0022] Figure 2 A specific example diagram of the three-dimensional printing extrusion filament cross-section model in the embodiments of the present application;

[0023] Figure 3 An overlapping area calculation schematic diagram in the embodiments of the present application;

[0024] Figure 4 A path offset schematic diagram in the embodiments of the present application Figure 1 ;

[0025] Figure 5 A path offset schematic diagram in the embodiments of the present application Figure 2 ;

[0026] Figure 6 A target overlapping area schematic diagram in the embodiments of the present application;

[0027] Figure 7 A to-be-printed curved surface model schematic diagram in the embodiments of the present application;

[0028] Figure 8 A printing effect schematic diagram of the to-be-printed curved surface model in the embodiments of the present application;

[0029] Figure 9 A specific example diagram of the method for generating a three-dimensional printing path facing a curved surface in the embodiments of the present application;

[0030] Figure 10 A schematic diagram of the device for generating a three-dimensional printing path facing a curved surface in the embodiments of the present application. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solutions and advantages of the embodiments of the present application more clear, the following will further describe the embodiments of the present application in combination with the drawings. Herein, the illustrative embodiments of the present application and their descriptions are used to explain the present application, but not as a limitation of the present application.

[0032] In order to clearly describe the technical solutions of the embodiments of the present application, in the embodiments of the present application, the terms "first", "second", etc. are used to distinguish the same or similar items with basically the same function and role, and those skilled in the art can understand that the terms "first", "second", etc. do not limit the quantity and execution order.

[0033] In the technical solutions of the present application, the acquisition, storage, use, processing, etc. of data comply with the relevant provisions of national laws and regulations.

[0034] First, the technical terms related to the present application are introduced.

[0035] Three-dimensional printing: an industrial manufacturing technology that heats materials and extrudes, melts, and forms them.

[0036] Path generation: in the computer-aided manufacturing process, a machining path is planned through a certain algorithm, so that the machining equipment can control the material removal or accumulation forming according to the planned path to manufacture the target part.

[0037] An existing curved surface three-dimensional printing method is to first determine the process parameters and corresponding cross-sectional dimensions of single-channel forming according to the model parameters, then directly construct the path surface of the entire model in three-dimensional space using these parameters and dimensions, and then slice the path surface to obtain the layered surface and its contour line of each layer. However, in fact, this method only decomposes the part into relatively simple voxels, and at the same time, adjusts the forming direction of the manufacturing surface, and still obtains the layered contour through the traditional plane slicing technology, and then performs plane contour filling and path connection. Its essence does not change the characteristics of plane layering forming, and the range of the manufactured curved surface is very limited. For slightly complex parts, it is difficult to form according to this method, and its essence cannot be considered as a path generation technology for curved surfaces.

[0038] Another existing curved surface three-dimensional printing method uses the concept of residual height in subtractive machining curved surface path generation, but it cannot directly control the material melting quality and curved surface manufacturing precision of three-dimensional printing, and it can only meet the curved surface manufacturing requirements of small curvature, otherwise the printing nozzle vector direction will deviate seriously from the curved surface normal vector, affecting the printing effect.

[0039] In general, there is a lack of curved surface path generation method suitable for the process characteristics in the prior art, which restricts the further improvement and promotion of the manufacturing quality of curved surface three-dimensional printing technology.

[0040] In order to solve the defects in the prior art, the embodiment of the present application proposes a method taking the cross-sectional area of the three-dimensional printing extrusion filament as the path bias basis, and a flowchart for the polygon discrete grid surface is connected, and a calculation method of the optimal overlap area is proposed. The method is a method suitable for three-dimensional printing manufacturing features, which can obtain high-quality three-dimensional printing surface manufacturing path, and has good algorithm robustness and efficiency.

[0041] Figure 1 The flowchart of the three-dimensional printing path generation method for the surface in the embodiment of the present application is shown in Figure 1 The method comprises the following steps:

[0042] Step 101, constructing a grid surface based on a to-be-printed surface model;

[0043] Step 102, selecting the boundary of the grid surface as an initial path; the initial path comprises a plurality of path points;

[0044] Step 103, taking the initial path as a current path, and performing the following loop operation steps 1031 to 1033 on the current path until a plurality of bias paths are obtained:

[0045] Step 1031, performing the following operation steps 1031.1 to 1031.4 on each path point on the current path until a bias path point corresponding to each path point is obtained:

[0046] Step 1031.1, constructing a reference plane passing through the current path point and taking the tangent direction of the current path as the normal direction of the reference plane;

[0047] Step 1031.2, determining the intersection line segment of the reference plane and the grid surface in the reference plane;

[0048] Step 1031.3, calculating the first overlap area and the second overlap area of the drum-shaped section created based on the two end points of the intersection line segment and the drum-shaped section created based on the current path point, respectively; the drum-shaped section is the cross-sectional shape of the three-dimensional printing extrusion filament;

[0049] Step 1031.4, if the target overlap area is between the first overlap area and the second overlap area, the bias path point corresponding to the current path point is determined on the intersection line segment by iteration using the bisection method; wherein the third overlap area of the drum-shaped section created based on the bias path point and the drum-shaped section created based on the current path point satisfies the preset difference requirement;

[0050] Step 1032, connecting the bias path point corresponding to each path point on the current path to obtain the bias path of the current path;

[0051] Step 1033: Update the bias path to the current path;

[0052] Step 104: Connect all offset paths end-to-end according to their adjacent positions to obtain the 3D printing path.

[0053] The method for generating 3D printing paths for curved surfaces in the embodiments of the present invention will be explained in detail below.

[0054] In this embodiment of the invention, the path generation for curved surface 3D printing includes some key technical points: 3D printing extrusion filament cross-section model, overlap area calculation, path offset method, target overlap area setting, etc.

[0055] (1) Three-dimensional printed extruded filament cross-section model.

[0056] In this embodiment of the invention, the cross-sectional shape of the 3D printing extrusion filament is a drum-shaped cross-section. The drum-shaped cross-section is racetrack-shaped, comprising two circular arcs and a straight line segment in the middle.

[0057] Figure 2 This is a specific example diagram of the cross-sectional model of the three-dimensional printed extruded filament in an embodiment of the present invention, such as... Figure 2 As shown, the right side displays a three-dimensional view of the extruded filament, while the left side displays the cross-section of the extruded filament, i.e., the drum-shaped cross-section model. The overall length of the drum-shaped cross-section is w, the radius of the arcs on both sides is R, the length of the rectangle in the middle is l, and the height is h. The drum-shaped cross-section model used in this embodiment of the invention is a good simulation of the actual shape of the extruded filament in 3D printing, and it can more accurately reproduce the actual printing process, resulting in a more reasonable calculation of the extrusion amount.

[0058] (2) Calculation of overlapping area.

[0059] like Figure 2 As shown in the embodiment of the present invention, the cross section of the three-dimensional printing extrusion filament is regarded as a drum-shaped closed segmented analytical body cross section composed of two semi-circular arcs and a direct line, and the overlapping area of ​​the drum-shaped cross sections of the two paths is used as the basis for path offset.

[0060] Figure 3 This is a schematic diagram illustrating the calculation of overlapping area in an embodiment of the present invention, as shown below. Figure 3 As shown, the overlapping area of ​​the drum-shaped cross-section is an irregular shape with an arc. Its area calculation can be decomposed into the polygon area and the additional area brought by the arc. By adding the two areas together, the intersection area of ​​the two drum-shaped cross-sections in any position can be solved. Figure 3 In the intersection section, each vertex Represented as The intersection point coordinates are calculated based on basic analytic geometry algorithm, which is not described herein. In actual implementation, the intersection point of the intersection section is calculated based on a local Cartesian coordinate system, the original center of which is located at the current path point, the x-axis is the offset direction f of the current path point, and the y-axis is the normal vector of the face sheet where the current path point is located. In the embodiment, the first overlapping area and the second overlapping area of the drum-shaped section created based on the two end points of the intersection line segment and the drum-shaped section created based on the current path point are calculated, which can include:

[0061] The overlapping area of the two drum-shaped sections is calculated according to the following formula:

[0062] S overlap =S polygon +S extra ;

[0063] Wherein, S overlap is the overlapping area, S polygon is the polygon area, and S extra is the difference between the sector area composed of the circular arc and the center and the polygon area composed of the start and end points of the circular arc and the center.

[0064] Further, S polygon and S extra can be expressed as follows:

[0065] ;

[0066] ;

[0067] Wherein, n is the number of vertices of the polygon, are the x coordinates of the intersection points of the intersecting polygon, are the y coordinates of the intersection points of the intersecting polygon, denotes the start intersection point of the intersecting arc, denotes the end intersection point of the intersecting arc, is the radian of the arc corresponding to the start intersection point of the intersecting arc, is the radian of the arc corresponding to the end intersection point of the intersecting arc, denotes the triangle composed of the intersection arc center and the start and end intersection points, wherein, the subscript i of x i indicates that it is a general term, which can be used to traverse the polygon coordinates based on the size of i.

[0068] (3) Path offset method.

[0069] Since path generation depends on the previous path, the full path used to create the surface is actually generated by continuously offsetting an initial path. Path offsetting refers to calculating the corresponding points on the next path to be generated for specific points in the current path according to certain rules. By traversing all points on the current path and offsetting them, the next path can be generated. By simply repeating the offsetting process, the path can be filled to cover the entire surface to be printed.

[0070] In this embodiment, an initial path on a discrete surface is selected. Based on the equal overlap area of ​​adjacent paths, a reference plane is established with the tangent of the previous path as the normal. Within this reference plane, the surface is intercepted to form multiple line segments. The path points on adjacent paths are then calculated on the line segments using the bisection method. Figure 4 This is a schematic diagram of path offset in an embodiment of the present invention. Figure 4 In the middle, the current path point is p i,j Specifically, it refers to the coordinates of the j-th path point on the i-th path, n i,j Indicates the current path point p i,j The normal vector t of the corresponding patch of the mesh surface i,j Indicates the current path point p i,j The direction pointing to the next path point, or the tangent of path i at path point j, where AB is the intersection of the reference plane and the mesh surface, f i,j Defined as the bias direction, f i,j =t i,j ×n i,j . t i,j It can be represented as:

[0071] ;

[0072] In the formula, the subscripts i and j represent the j-th path point of the i-th path.

[0073] Figure 5 This is a schematic diagram of path offset in an embodiment of the present invention. Figure 2 , Figure 5 p i+1,j For the current path point p i,j The offset path point, Figure 5 The overlapping areas shown are equal to or less than a preset difference. This can be expressed as:

[0074] (4) Target overlap area setting.

[0075] Unlike traditional subtractive manufacturing, dense paths do not necessarily improve the manufacturing quality of 3D printing, as excessively dense paths will cause material buildup. Therefore, based on the principle of equal overlap area in this embodiment of the invention, in a preferred embodiment, the gap area between adjacent extruded filament drum cross-sections is selected as the target overlap area to obtain the basis for the discrete surface mesh path offset. Figure 6For the target overlapping area in the embodiment of the present application, the target overlapping area can be represented as follows:

[0076] ;

[0077] In the formula, S Target is a pre-set target overlapping area, R is the radius of the circular arc, and d is the distance between the centers of the two adjacent arcs in the drum-shaped cross section that generates the intersection, .

[0078] The following describes Figure 1 each step.

[0079] Step 101 constructs a mesh surface based on a to-be-printed curved surface model.

[0080] For example, a polygon mesh surface obtained by discretizing a NURBS (Non-Uniform Rational B-Splines) curved surface. Figure 7 For the to-be-printed curved surface model in the embodiment of the present application, refer to Figure 7 , and generate a three-dimensional printing path of the polygon mesh surface that can be uniformly manufactured based on the curved surface shown in Figure 7 .

[0081] In the embodiment, in order to better obtain the intersection line segment, a half-edge topological model of the mesh surface is established, and a three-dimensional topological model without redundant data is established, so as to quickly find the intersection line segment of the reference plane and the mesh surface.

[0082] Step 102 selects the boundary of the mesh surface as an initial path; the initial path includes a plurality of path points.

[0083] For example, the discrete multi-line segment corresponding to the u-line in the NURBS curved surface is selected as the initial path, that is, the boundary of the mesh surface is selected as the initial path.

[0084] Step 103 records the initial path as a current path, and starts from the current path to offset each path. Once a new path is generated, the new path is set as the current path, and the offsetting is continued.

[0085] Specifically, the following operations are performed on each path point on the current path until the offset path point corresponding to each path point is obtained:

[0086] Step 1031.1, a reference plane passing through the current path point and having a tangent direction of the current path as a normal direction is constructed. For example, Figure 4 the reference plane in .

[0087] Step 1031.2, the intersection line segment of the reference plane and the mesh surface is determined in the reference plane.

[0088] In the actual operation process, the intersection line segments of the reference plane and the patches are obtained step by step.

[0089] Specifically, in an embodiment, determining the intersection line segments of the reference plane and the mesh surface in the reference plane can include:

[0090] determining the intersection line segments of the reference plane and the patch in which the current path point is located in the reference plane;

[0091] After the first overlap area and the second overlap area of the drum-type cross sections created based on the two end points of the intersection line segment and the drum-type cross section created based on the current path point are calculated respectively, Figure 1 The method can further include:

[0092] If the target overlap area set in advance is not between the first overlap area and the second overlap area, determining the intersection line segments of the reference plane and the next patch of the patch in which the current path point is located in the reference plane; wherein one of the two end points of the intersection line segment is on the next patch.

[0093] For example, referring to Figure 4 When the polygon mesh model is read in, the topological relationship of the vertices, half-edges and patches is established, the intersection line segment AB is obtained by intersecting the reference plane and the patch in which the current tool position point is located, and the first and last points A and B in the intersection line segment are adjusted so that the line segment direction AB and the offset direction f i,j form an acute angle, then the next patch can be searched through the relationship between the end point B of the line segment and the half-edges and topological patches.

[0094] Step 1031.3, calculating the first overlap area and the second overlap area of the drum-type cross sections created based on the two end points of the intersection line segment and the drum-type cross section created based on the current path point, respectively; the drum-type cross section is the cross section shape of the three-dimensional printing extrusion filament.

[0095] For example, the first overlap area and the second overlap area of the drum-type cross sections created based on the two end points of the intersection line segment and the drum-type cross section created based on the current path point are calculated respectively. Referring to Figure 4 、 Figure 5 , the path point is located on the straight line segment of the drum-type cross section.

[0096] Step 1031.4, if the target overlap area set in advance is between the first overlap area and the second overlap area, the current path point corresponding to the offset path point is determined on the intersection line segment by bisection iteration; wherein the third overlap area of the drum-type cross section created based on the offset path point and the drum-type cross section created based on the current path point meets the preset difference requirement of the target overlap area.

[0097] At the start and end points AB of the current intersection line segment, the overlapping area between the drum-shaped section generated between the points A and B and the current path point is checked, and if the preset target overlapping area is within the range of the calculated overlapping area corresponding to the start and end points, the offset path point is obtained through bisection iteration.

[0098] In the case where it has been determined that there is an offset path point on the current intersection line segment, the start and end points of the intersection line segment are taken as initial iteration points, and the offset path point satisfying the target overlapping area requirement is quickly obtained through bisection.

[0099] Step 1032, connecting the offset path points corresponding to each path point on the current path to obtain the offset path of the current path.

[0100] Step 1033, updating the offset path to the current path.

[0101] End the path offset, and connect the separated path points to obtain a continuous curved manufacturing path.

[0102] Step 104, connecting all offset paths in a head-to-tail manner according to adjacent positions to obtain a three-dimensional printing path, that is, a final continuous curved manufacturing path.

[0103] In an embodiment, in order to further clearly determine the appropriate end of the path offset, step 1031.3, after the first overlapping area and the second overlapping area of the drum-shaped sections created based on the two end points of the intersection line segment and the drum-shaped section created based on the current path point are calculated respectively, Figure 1 The method further comprises:

[0104] If the preset target overlapping area is between the first overlapping area and the second overlapping area, the offset path point corresponding to the current path point cannot be iteratively obtained on the intersection line segment through bisection, which indicates that the boundary has been reached, the path offset is completed, and the loop is exited.

[0105] Figure 8 A printing effect diagram of the curved surface model to be printed in the embodiment of the present application is based on Figure 7 The final path generated is used for manufacturing simulation, and the result is as shown in Figure 8 It can be seen that the cladding is uniform, the shape meets the requirements, and a high-quality three-dimensional printed curved surface can be predicted.

[0106] Figure 9 A specific example diagram of the curved surface-oriented three-dimensional printing path generation method in the embodiment of the present application is shown in Figure 9As shown in the method, the target overlapping area STarget is given in advance; then the grid surface boundary is selected as an initial path, and a calculation method of a supposed bias direction f is set; in the case that f is a valid bias direction, the subscript i=0 is initialized, and it is further judged whether the path i is empty, and in the case that the path i is not empty, j=0 is initialized, it is judged whether j Figure 1 The method shown obtains the intersection line segment, and determines the bias path point by bisection until the bias of all paths is obtained. paths[i].size() represents the number of path points in the current bias path, so j is initialized to 0 and continuously increases until it is equal to paths[i].size() and the loop is exited, and in fact, all path points of the current path i are traversed and biased.

[0107] In summary, the embodiment of the present application proposes a more reasonable three-dimensional printing curved surface path bias basis-equal overlapping area bias basis. In the embodiment of the present application, when the overlapping area is equal to the empty area, the material cladding can achieve uniform filling and no underfilling and overfilling. The method selects the overlapping area, which can predict the reduction of the manufacturing curved surface roughness and the improvement of the mechanical properties and quality of the manufacturing curved surface. In the method, the path bias is directly performed on the discrete polygonal surface, which does not depend on the geometric characteristics of the continuous curved surface, expands the available range of path point bias, improves the robustness and reliability of path generation, and can directly control the density of the material cladding of the three-dimensional printing manufacturing curved surface and ensure uniform accumulation at the same time.

[0108] The embodiment of the present application also provides a curved surface-oriented three-dimensional printing path generation device, as described in the following embodiment. Since the principle of solving the problem of the device is similar to that of the curved surface-oriented three-dimensional printing path generation method, the implementation of the device can be referred to the implementation of the curved surface-oriented three-dimensional printing path generation method, and the repeated parts will not be described again.

[0109] Figure 10 A schematic diagram of the curved surface-oriented three-dimensional printing path generation device in the embodiment of the present application is shown in the following figure. Figure 10 As shown in the figure, the device 1000 includes:

[0110] The grid surface construction module 1001 is configured to construct a grid surface based on a to-be-printed curved surface model;

[0111] The initial path confirmation module 1002 is configured to select the boundary of the grid surface as an initial path; the initial path includes a plurality of path points;

[0112] The path bias module 1003 is configured to record the initial path as a current path, and perform a loop operation on the current path until a plurality of bias paths are obtained;

[0113] The three-dimensional printing path determination module 1004 is configured to connect all the offset paths in sequence to obtain a three-dimensional printing path.

[0114] The above-mentioned loop operation comprises:

[0115] Step 1: performing the following steps 1.1 to 1.4 on each path point on the current path until the offset path point corresponding to each path point is obtained:

[0116] Step 1.1: constructing a reference plane passing through the current path point and having a tangent direction of the current path as a normal direction;

[0117] Step 1.2: determining a line segment of intersection of the reference plane and the mesh surface in the reference plane;

[0118] Step 1.3: calculating a first overlap area and a second overlap area of a drum-shaped section created based on two end points of the line segment of intersection and a drum-shaped section created based on the current path point, respectively; the drum-shaped section is a cross-sectional shape of the three-dimensional printing extrusion filament;

[0119] Step 1.4: if a preset target overlap area is between the first overlap area and the second overlap area, iteratively determining the offset path point corresponding to the current path point on the line segment of intersection by bisection; wherein a third overlap area of the drum-shaped section created based on the offset path point and the drum-shaped section created based on the current path point satisfies a preset difference requirement with the target overlap area;

[0120] Step 2: connecting the offset path point corresponding to each path point on the current path to obtain an offset path of the current path;

[0121] Step 3: updating the offset path as the current path.

[0122] In an embodiment, the drum-shaped section is a racetrack shape, a circular arc including two segments and a straight line segment in the middle;

[0123] The path offsetting module 1003 is specifically configured to:

[0124] The overlap area of the two drum-shaped sections is calculated according to the following formula:

[0125] S overlap =S polygon +S extra ;

[0126] Wherein, S overlap is the overlap area, S polygon is the polygon area, and S extra is a difference between a sector area of a circular arc and a center and a polygon area of start and end points of the circular arc and the center.

[0127] In an embodiment, the path biasing module 1003 is specifically configured to:

[0128] The first overlap area and the second overlap area are respectively calculated as the first overlap area and the second overlap area between a drum-shaped section created at an arbitrary point on a straight line segment with two end points of the intersection line segment and a drum-shaped section created at an arbitrary point on a straight line segment with the current path point as a drum-shaped section.

[0129] In an embodiment, the target overlap area is set as a gap area of two adjacent extruded wire drum-shaped sections.

[0130] In an embodiment, the target overlap area is represented as follows:

[0131] ;

[0132] In the formula, S Target is a pre-set target overlap area, R is a radius of a circular arc, d is a distance between centers of two adjacent arcs in the two drum-shaped sections that generate the overlap, .

[0133] In an embodiment, the path biasing module 1003 is specifically configured to:

[0134] determining an intersection line segment of the reference plane and a next patch of the patch on the mesh surface in the reference plane, wherein one of the two end points of the intersection line segment is on the next patch.

[0135] After the first overlap area and the second overlap area between the drum-shaped section created based on the two end points of the intersection line segment and the drum-shaped section created based on the current path point are respectively calculated, if the pre-set target overlap area is not between the first overlap area and the second overlap area, determining an intersection line segment of the reference plane and the next patch of the patch on the mesh surface in the reference plane, wherein one of the two end points of the intersection line segment is on the next patch.

[0136] The embodiment of the present application further provides a computer device, including a memory, a processor and a computer program stored in the memory and executable on the processor, and the processor implements the above-mentioned curved surface-oriented three-dimensional printing path generation method when executing the computer program.

[0137] The embodiment of the present application further provides a computer readable storage medium, which stores a computer program, and the computer program is executable on a processor to implement the above-mentioned curved surface-oriented three-dimensional printing path generation method.

[0138] The embodiment of the present application further provides a computer program product, which includes a computer program, and the computer program is executable on a processor to implement the above-mentioned curved surface-oriented three-dimensional printing path generation method.

[0139] The direct bias basis for three-dimensional printing curved surface path generation is provided in the embodiment of the present application, if the preset target overlap area is between the first overlap area and the second overlap area, the bias path point corresponding to the current path point is determined on the intersection line segment by bisection iteration; wherein the third overlap area of the drum-type cross section created based on the bias path point and the drum-type cross section created based on the current path point meets the preset difference requirement, that is, the equal overlap area bias basis, in the method, when the overlap area is equal to the preset target overlap area, the material cladding can achieve uniform filling and no underfilling and overfilling, through the embodiment of the present application, the density of the material cladding of the curved surface three-dimensional printing manufacturing can be directly controlled and uniform accumulation is ensured at the same time, the manufacturing curved surface roughness can be reduced, and the mechanical properties and quality of the manufacturing curved surface are improved.

[0140] Those skilled in the art will appreciate that embodiments of the present application can be provided as methods, systems, or computer program products. Accordingly, the present application can take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present application can take the form of a computer program product on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROMs, optical storage devices, etc.) having computer usable program code embodied in the medium.

[0141] The present application is described with reference to flowcharts and / or block diagrams of the method, device (system), and computer program product according to the embodiments of the present application. It should be understood that each flow and / or block in the flowcharts and / or block diagrams, and the combination of flows and / or blocks in the flowcharts and / or block diagrams 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 apparatus to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing apparatus produce a device that implements the functions specified in the flowcharts and / or block diagrams. Figure 1 The functions specified in one or more flows and / or blocks Figure 1 The means for performing the functions specified in one or more flows and / or blocks.

[0142] These computer program instructions can also be stored in a computer-readable memory that can direct the computer or other programmable data processing apparatus to work in a specific manner, so that the instructions stored in the computer-readable memory produce a manufactured product including instruction means, which implements the functions specified in the flowcharts and / or block diagrams. Figure 1 The functions specified in one or more flows and / or blocks Figure 1 The means for performing the functions specified in one or more flows and / or blocks.

[0143] These computer program instructions can also be loaded into a computer or other programmable data processing devices, so that a series of operational steps are performed on the computer or other programmable data processing devices to generate a computer implemented process, so that the instructions executed on the computer or other programmable data processing devices provide a process for implementing the flowchart Figure 1 one flow or multiple flows and / or the functions specified in the block Figure 1 one flow or multiple flows and / or the functions specified in the block

[0144] The above described specific embodiments, the purpose, technical solutions and beneficial effects of the present application are further described in detail, it should be understood that the above described is only a specific embodiment of the present application, and is not used to limit the protection scope of the present application, any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A method for generating a three-dimensional printing path for a curved surface, the method comprising: The method comprises the following steps: constructing a mesh surface based on a curved surface model to be printed; selecting a boundary of the mesh surface as an initial path; the initial path comprises a plurality of path points; the initial path is recorded as a current path, and the following steps 1 to 3 are performed on the current path in a loop until a plurality of offset paths are obtained: step 1: the following steps 1.1 to 1.4 are performed on each path point on the current path until an offset path point corresponding to each path point is obtained: step 1.1: constructing a reference plane passing through the current path point and having a tangent direction of the current path as a normal direction; step 1.2: determining a line segment of intersection of the reference plane and the mesh surface in the reference plane; step 1.3: calculating a first overlap area of a drum-shaped section created based on one end point of the line segment of intersection and a drum-shaped section created based on the current path point, and a second overlap area of a drum-shaped section created based on the other end point of the line segment of intersection and the drum-shaped section created based on the current path point; the drum-shaped section is a cross-sectional shape of an extrusion filament for three-dimensional printing; step 1.4: if a preset target overlap area is between the first overlap area and the second overlap area, iteratively determining the offset path point corresponding to the current path point on the line segment of intersection by bisection method; wherein a third overlap area of a drum-shaped section created based on the offset path point and a drum-shaped section created based on the current path point meets a preset difference requirement with the target overlap area; the target overlap area is a void area of adjacent extrusion filament drum-shaped sections; step 2: connecting the offset path point corresponding to each path point on the current path to obtain an offset path of the current path; step 3: updating the offset path as the current path; connecting all the offset paths end to end according to adjacent positions to obtain a three-dimensional printing path.

2. The method of claim 1, wherein, The drum-shaped section is a racetrack shape, comprising two circular arcs and a straight line segment in between; the first overlap area and the second overlap area are calculated by the following steps: calculating the overlap area of the two drum-shaped sections according to the following formula: S overlap = S polygon + S extra ； wherein, S overlap is the area of the overlapping region, S polygon is the area of the polygon, S extra is the difference between the area of the sector formed by the circular arc and the center of the circle and the area of the polygon formed by the start and end points of the circular arc and the center of the circle.

3. The method of claim 2, wherein, the first overlap area and the second overlap area are calculated by the following steps: the first overlap area and the second overlap area are calculated by the following steps:

4. The method of claim 2, wherein, the first overlap area and the second overlap area are calculated by the following steps:

5. The method of claim 4, wherein, the target overlap area is set as a void area of two adjacent extrusion filament drum-shaped sections. ； In the formula, S target is a pre-set target overlapping area, R is a radius of the circular arc, d is a distance between the centers of the two arcs in the drum cross section, .

6. The method of claim 1, wherein, The target overlap area is represented as follows: determining the line segment of intersection of the reference plane and the mesh surface in the reference plane comprises: determining the line segment of intersection of the reference plane and a face sheet on which the current path point is located in the mesh surface in the reference plane; after the first overlap area and the second overlap area are calculated by the following steps: If the preset target overlap area is not between the first overlap area and the second overlap area, a reference plane and a next patch of the patch on which the current path point of the mesh surface is located are determined in the reference plane to obtain a cross line segment; one of two end points of the cross line segment is on the next patch.

7. A computer device comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, The processor implements the method in any of claims 1-6 when executing the computer program.

8. A computer-readable storage medium, characterized in that, The computer readable storage medium stores a computer program, and the computer program is executed by the processor to implement the method in any of claims 1-6.

9. A computer program product, characterised in that, The computer program product comprises a computer program, and the computer program is executed by the processor to implement the method in any of claims 1-6.

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