Curved surface-oriented three-dimensional printing path generation method and device

Abstract

The invention discloses a curved surface-oriented three-dimensional printing path generation method and device. The method comprises the following steps: selecting a boundary of a grid curved surface as an initial path; marking the initial path as a current path to perform path offset circulation operation, and finally forming a three-dimensional printing path based on all offset paths, and the path offset is as follows: constructing a reference plane which passes through a current path point and takes a tangent vector direction of the current path as a normal vector direction; determining an intersection line segment of the reference plane and the grid curved surface in the reference plane; respectively calculating to obtain two overlapping areas of the drum-shaped cross section created based on the two end points of the intersection line segment and the drum-shaped cross section created based on the current path point; if the target overlapping area is between the two overlapping areas, iteratively determining a bias path point on the intersection line segment by using a dichotomy method; and connecting the offset path points corresponding to the path points to obtain an offset path of the current path. The manufacturing precision of the three-dimensional printing curved surface can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of three-dimensional printing, and in particular to a method and device for generating a three-dimensional printing path for a curved surface. Background Art

[0002] Traditional 3D printing is a manufacturing technology based on the gradual accumulation of materials layer by layer. While this provides good process stability and simplifies the manufacturing principles, it also results in a significant step effect in the printed parts, negatively impacting the surface quality and mechanical properties of the manufactured products. Surface 3D printing is an advanced technology of traditional 3D printing, primarily designed for high-precision molding of objects with complex curved structures (such as free-form and irregular surfaces).

[0003] However, existing curved surface 3D printing processes simply decompose parts into relatively simple voxels, adjust the forming direction of the manufactured surface, and still use traditional plane slicing technology to obtain layered contours, then fill in the plane contours and connect the paths. This fundamentally does not change the characteristics of planar layered forming, resulting in the printed product still having low quality and performance defects. The concept of equal residual height has been proposed in existing curved surface 3D printing processes, but it cannot meet the manufacturing requirements of surfaces with large curvatures, resulting in poor precision of the final printed product, rough surfaces, low quality, and low mechanical properties. Summary of the Invention

[0004] An embodiment of the present invention provides a method for generating a three-dimensional printing path for a curved surface, which is used to improve the manufacturing accuracy of the curved surface, reduce roughness, and enhance the manufacturing quality and mechanical properties of the curved surface. The method includes: Construct a mesh surface based on the surface model to be printed; Selecting a boundary of the mesh surface as an initial path; the initial path includes a plurality of path points; The initial path is recorded as the current path, and the following steps 1 to 3 are repeated for the current path until multiple offset paths are obtained: Step 1: Perform the following steps 1.1 to 1.4 for each path point on the current path until the offset path point corresponding to each path point is obtained: Step 1.1: Construct a reference plane passing through the current path point and with the tangent vector direction of the current path as the normal direction; Step 1.2: Determine the intersection line segment between the reference plane and the mesh surface within the reference plane; Step 1.3: Calculate the first overlapping area and the second overlapping area of ​​the drum-shaped section created based on the two endpoints of the intersection line segment and the drum-shaped section created based on the current path point; the drum-shaped section is the cross-sectional shape of the 3D printing extruded filament; Step 1.4: If the preset target overlap area is between the first overlap area and the second overlap area, iteratively determine the offset path point corresponding to the current path point on the intersection line segment using a bisection method; wherein the third overlap area of ​​the drum section created based on the offset path point and the drum section created based on the current path point meets a preset difference requirement with the target overlap area; 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; Step 3: Update the bias path to the current path; All offset paths are connected end to end at adjacent positions to obtain a three-dimensional printing path.

[0005] An embodiment of the present invention further provides a computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the above-mentioned surface-oriented three-dimensional printing path generation method when executing the computer program.

[0006] An embodiment of the present invention further provides a computer-readable storage medium storing a computer program. When the computer program is executed by a processor, the computer program implements the above-mentioned method for generating a curved surface-oriented three-dimensional printing path.

[0007] An embodiment of the present invention further provides a computer program product, which includes a computer program. When the computer program is executed by a processor, it implements the above-mentioned method for generating a three-dimensional printing path for a curved surface.

[0008] In an embodiment of the present invention, a direct offset basis for generating a three-dimensional printing surface path is proposed. If a preset target overlapping area is between a first overlapping area and a second overlapping area, the offset path point corresponding to the current path point is iteratively determined on the intersection line segment by bisection; wherein the third overlapping 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 and the target overlapping area meet the preset difference requirement, that is, the equal overlapping area offset basis. In this method, it is believed that when the overlapping area is equal to the preset target overlapping area, the material cladding can achieve uniform filling without under- or over-accumulation. Through the embodiment of the present invention, the density of the material cladding for three-dimensional printing of the surface can be directly controlled while ensuring its uniform accumulation, which can reduce the roughness of the manufactured surface and improve the mechanical properties and quality of the manufactured surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work. In the drawings:

[0010] Figure 1 Schematic diagram of the process of generating a curved surface 3D printing path according to an embodiment of the present invention;

[0011] Figure 2 A diagram showing a specific example of a cross-sectional model of a three-dimensionally printed extruded filament in an embodiment of the present invention;

[0012] Figure 3 Schematic diagram of overlapping area calculation in an embodiment of the present invention;

[0013] Figure 4 Schematic diagram of path bias in an embodiment of the present invention Figure 1 ;

[0014] Figure 5 Schematic diagram of path bias in an embodiment of the present invention Figure 2 ;

[0015] Figure 6 Schematic diagram of target overlapping area in an embodiment of the present invention;

[0016] Figure 7 Schematic diagram of a curved surface model to be printed in an embodiment of the present invention;

[0017] Figure 8 Schematic diagram of the printing effect of the curved surface model to be printed in an embodiment of the present invention;

[0018] Figure 9 A diagram showing a specific example of a method for generating a curved surface 3D printing path according to an embodiment of the present invention;

[0019] Figure 10 Schematic diagram of a device for generating a three-dimensional printing path for a curved surface in an embodiment of the present invention. DETAILED DESCRIPTION

[0020] To make the purpose, technical solutions and advantages of the embodiments of the present invention more clear, the embodiments of the present invention are further described in detail below with reference to the accompanying drawings. Here, the exemplary embodiments of the present invention and their descriptions are used to explain the present invention, but are not intended to limit the present invention.

[0021] In order to clearly describe the technical solutions of the embodiments of the present invention, in the embodiments of the present invention, words such as "first" and "second" are used to distinguish between identical or similar items with basically the same functions and effects. Those skilled in the art can understand that words such as "first" and "second" do not limit the quantity and execution order.

[0022] The acquisition, storage, use, and processing of data in this application's technical solution comply with relevant national laws and regulations.

[0023] First, the technical terms involved in the present invention are introduced.

[0024] 3D printing: An industrial manufacturing technology that heats materials and extrude, fuses, and forms them.

[0025] Path generation: In the computer-aided manufacturing process, the processing path is planned through a certain algorithm, so that the processing equipment can control the material removal or accumulation according to the planned path to manufacture the target part.

[0026] One existing method for 3D printing curved surfaces first determines the process parameters and corresponding cross-sectional dimensions for a single pass based on model parameters. These parameters and dimensions are then used to directly construct a path surface for the entire model in 3D space. This path surface is then sliced ​​layer by layer to obtain the layered surface and its contour lines for each layer. However, this method only decomposes the part into relatively simple voxels, adjusting the forming direction of the manufactured surface. It still uses traditional plane slicing technology to obtain the layered contours, then fills the plane contours and connects them with the path. This process essentially does not change the characteristics of plane layered forming. Furthermore, the range of surfaces that can be manufactured is very limited, making it difficult to form even slightly complex parts using this method. Furthermore, it cannot be considered a path generation technology for curved surfaces.

[0027] Another existing surface 3D printing method uses the concept of generating a medium residual height by using a subtractive machining surface path. However, it cannot intuitively control the material cladding quality and surface manufacturing accuracy of 3D printing, and it can only meet the manufacturing requirements of surfaces with not too large curvature. Otherwise, the print head vector direction will have a serious deviation from the surface normal vector, affecting the printing effect.

[0028] In general, the existing technology lacks a surface path generation method that is adapted to its process characteristics, which restricts the further improvement and promotion of the manufacturing quality of surface 3D printing technology.

[0029] To address the shortcomings of existing technologies, the present invention proposes a method that uses the overlapping area of ​​3D printing extruded filament cross-sections as the basis for path offsets. This method also implements a process for polygonal discrete mesh surfaces and proposes a method for calculating the optimal overlapping area. This method is suitable for 3D printing manufacturing features, can obtain high-quality 3D printing surface manufacturing paths, and has good algorithmic robustness and efficiency.

[0030] Figure 1 FIG. 1 is a flow chart of a method for generating a curved surface 3D printing path according to an embodiment of the present invention. Figure 1 As shown, the method includes:

[0031] Step 101: constructing a mesh surface based on the surface model to be printed;

[0032] Step 102: Select the boundary of the mesh surface as an initial path; the initial path includes a plurality of path points;

[0033] Step 103: record the initial path as the current path, and repeat the following steps 1031 to 1033 on the current path until multiple offset paths are obtained: Step 1031: Perform the following operations, steps 1031.1 to 1031.4, for each path point on the current path until the offset path point corresponding to each path point is obtained:

[0034] Step 1031.1: Construct a reference plane passing through the current path point and with the tangent vector direction of the current path as the normal vector direction;

[0035] Step 1031.2: Determine the intersection line segment between the reference plane and the mesh surface within the reference plane.

[0036] Step 1031.3: Calculate the first overlapping area and the second overlapping area of ​​the drum-shaped section created based on the two endpoints of the intersection line segment and the drum-shaped section created based on the current path point; the drum-shaped section is the cross-sectional shape of the 3D printing extruded filament;

[0037] Step 1031.4: If the preset target overlap area is between the first overlap area and the second overlap area, iteratively determine the offset path point corresponding to the current path point on the intersection line segment using a bisection method; wherein the 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 meets the preset difference requirement with the target overlap area;

[0038] Step 1032: Connect the offset path points corresponding to each path point on the current path to obtain the offset path of the current path;

[0039] Step 1033: Update the offset path to the current path;

[0040] Step 104: Connect all the offset paths end to end at adjacent positions to obtain a three-dimensional printing path.

[0041] The following is a detailed explanation of the method for generating a curved surface 3D printing path in an embodiment of the present invention.

[0042] In the embodiment of the present 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.

[0043] (1) 3D printed extruded filament cross-section model.

[0044] In an embodiment of the present invention, the cross-section of the 3D printing extruded filament is a drum-shaped cross-section. The drum-shaped cross-section is in the shape of a racetrack and includes two circular arc segments and a straight line segment in the middle.

[0045] Figure 2 Detailed example of a cross-sectional model of a three-dimensionally printed extruded wire according to an embodiment of the present invention. Figure 2 As shown, the right side shows a three-dimensional image of the extruded filament, and the left side shows a cross-section of the extruded filament, namely the drum-shaped cross-section model of the extruded filament. The drum-shaped cross-section has an overall length of w, a radius of the arcs on both sides of R, and a central rectangle with a length of l and a height of h. The drum-shaped cross-section model used in the embodiments of the present invention is a cross-sectional model that better simulates the shape of the actual extruded filament in 3D printing, can more accurately reproduce the actual printing process, and can obtain more reasonable extrusion amount calculation results.

[0046] (2) Calculation of overlapping area.

[0047] like Figure 2 As shown in , in an embodiment of the present invention, the cross section of the 3D printing extruded filament is regarded as a drum-shaped closed segmented analytical body cross section composed of two semicircular arcs and a straight line, and the overlapping area of ​​the drum-shaped cross section of the two paths is used as the offset basis of the path.

[0048] Figure 3 FIG. 1 is a schematic diagram of overlapping area calculation in an embodiment of the present invention, as shown in FIG. Figure 3 As shown in the figure, the overlapping area of ​​the drum-shaped section is an irregular figure with an arc. Its area calculation can be decomposed into the polygon area and the additional area brought by the arc. The intersection cross-sectional area of ​​the two drum-shaped sections in any position state can be solved by adding the two areas. Figure 3 In the intersection section, each vertex Expressed as (The calculation of the intersection coordinates is based on basic analytic geometry algorithms and is not detailed here.) In actual implementation, the intersection point of the intersection sections is calculated based on a local Cartesian coordinate system, with the origin of this coordinate system located at the current path point, the x-axis being the offset direction f of the current path point, and the y-axis being the normal vector of the patch at the current path point. In this embodiment, the first and second overlapping areas of the drum section created based on the two endpoints of the intersection line segment and the drum section created based on the current path point are calculated, respectively, and may include:

[0049] Calculate the overlapping area of ​​two drum sections using the following formula:

[0050] S overlap =S polygon +S extra ;

[0051] Among them, S overlap is the overlapping area, S polygon is the area of ​​the polygon, S extra The difference between the area of ​​the sector formed by the arc and the center of the circle and the area of ​​the polygon formed by the starting and ending points of the arc and the center of the circle.

[0052] Furthermore, S polygon and S extra It can be expressed as follows:

[0053] ;

[0054] ;

[0055] Where n is the number of vertices of the polygon, are the x-coordinates of the intersection points of the intersecting polygons, are the y coordinates of the intersection points of the intersecting polygons, Indicates the starting point of the intersecting arcs. Indicates the ending intersection point of the intersecting arcs, is the arc angle corresponding to the starting point of the intersecting arc, The arc angle corresponding to the ending point of the intersecting arc is Represents a triangle formed by the centers of the intersecting arcs and the starting and ending points, where x i The subscript i indicates that it is a general reference and can be used to traverse polygon coordinates based on the size of i.

[0056] (3) Path bias method.

[0057] Path generation depends on the previous path, so the entire surface path used for manufacturing is actually a continuous offset from an initial path. Path offsetting involves calculating the corresponding points on the next path to be generated based on specific points in the path according to certain rules. By traversing all points on the current path and applying the offset, the next path is generated. Simply repeating the offsetting process can create a path that covers the entire surface to be printed.

[0058] In this embodiment, an initial path on a discrete surface is selected, and based on the equal overlapping area of ​​adjacent paths, a reference plane is established with the tangent direction of the previous path as the normal. The surface is intercepted within the reference plane to form multiple line segments, and the path points on the adjacent paths are calculated using the bisection method on the line segments. Figure 4 This is a first diagram of path offset in an embodiment of the present invention. Figure 4 In the example, the current path point is p i,j , specifically the coordinates of the jth path point on the i-th path, n i,j Represents the current path point p i,j The normal vector of the corresponding patch on the mesh surface, t i,j Represents the current path point p i,j The direction pointing to the next path point, or the tangent direction of path i at path point j, AB is the intersection line segment between 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 expressed as:

[0059] ;

[0060] Where, subscripts i and j represent the jth path point of the i-th path.

[0061] Figure 5 Schematic diagram of path bias in an embodiment of the present invention Figure 2 , Figure 5 Medium i+1,j is the current path point p i,j The offset path point, Figure 5 The overlapping area shown in is equal to or less than the preset difference. It can be expressed as:

[0062] (4) Target overlapping area setting.

[0063] Unlike traditional subtractive processing, dense paths do not bring a positive correlation improvement to the manufacturing quality of 3D printing, because overly dense paths will cause material accumulation. Therefore, based on the equal overlapping area in the embodiment of the present invention, in a preferred embodiment, the gap area between adjacent extruded wire drum sections is selected as the target overlapping area to obtain the basis for the discrete surface mesh path offset. Figure 6This is a schematic diagram of the target overlapping area in an embodiment of the present invention. The target overlapping area can be expressed as follows:

[0064] ;

[0065] Where S Target is the preset target overlapping area, R is the radius of the arc, d is the distance between the centers of the two adjacent arcs in the intersecting drum sections, .

[0066] The following introduces Figure 1 Each step in the.

[0067] Step 101 constructs a mesh surface based on the surface model to be printed.

[0068] For example, a polygonal mesh surface obtained by discretizing a NURBS (Non-Uniform Rational B-Splines) surface. Figure 7 This is a schematic diagram of a surface model to be printed in an embodiment of the present invention, with reference to Figure 7 ,based on Figure 7 The surface shown generates a 3D printing path that can uniformly manufacture a polygonal mesh surface.

[0069] In order to better obtain the intersection line segments in the embodiment, a half-edge topology model is established for the mesh surface, and a three-dimensional topology model without redundant data is established to quickly find the intersection line segments between the reference plane and the mesh surface.

[0070] Step 102 selects the boundary of the mesh surface as an initial path; the initial path includes a plurality of path points.

[0071] For example, the discrete polyline segment corresponding to the u-line in the NURBS surface is selected as the initial path, that is, the boundary of the mesh surface is selected as the initial path.

[0072] Step 103: record the initial path as the current path, and start from the current path to offset each path. Once a new path is generated, set it as the current path and continue to offset.

[0073] The specific offset step is to perform the following operations on each path point on the current path until the offset path point corresponding to each path point is obtained:

[0074] Step 1031.1: Construct a reference plane that passes through the current path point and takes the tangent vector direction of the current path as the normal vector direction. Figure 4 Center reference plane.

[0075] Step 1031.2: Determine the intersection line segment between the reference plane and the mesh surface within the reference plane.

[0076] The reference plane intercepts the mesh surface to obtain multiple line segments in the same plane. In the actual operation process, the reference plane and the patch are gradually intersected to obtain line segments.

[0077] Specifically, in one embodiment, determining the intersection line segment between the reference plane and the mesh surface within the reference plane may include:

[0078] Determine the intersection line segment of the reference plane and the patch on the mesh surface where the current path point is located within the reference plane;

[0079] After respectively calculating the first overlapping area and the second overlapping area of ​​the drum section created based on the two endpoints of the intersection line segment and the drum section created based on the current path point, Figure 1 The method may further include:

[0080] If the preset target overlapping area is not between the first overlapping area and the second overlapping area, determine the intersection line segment between the reference plane and the next face of the face where the current path point is located on the grid surface within the reference plane; one of the two endpoints of the intersection line segment is on the next face.

[0081] For example, reference Figure 4 When reading in the polygonal mesh model, the topological relationship between vertices, half edges and patches is established. The reference plane is intersected with the patch where the current tool position is located to obtain the intersection line segment AB. The first and last points A and B in the intersection line segment are adjusted so that the line segment direction AB is consistent with the offset direction f. i,j If it forms an acute angle, the next face can be searched through the relationship between the end point B of the line segment and the half edge and the topological face.

[0082] Step 1031.3, respectively calculate the first overlapping area and the second overlapping area of ​​the drum-shaped section created based on the two endpoints of the intersection line segment and the drum-shaped section created based on the current path point; the drum-shaped section is the cross-sectional shape of the 3D printing extruded wire.

[0083] For example, the first overlapping area and the second overlapping area of ​​the drum section created by any point on the straight line segment with the two endpoints of the intersection line segment as the drum section and the drum section created by any point on the straight line segment with the current path point as the drum section are calculated respectively. Figure 4 、 Figure 5 , the path point is located on the straight line segment of the drum section.

[0084] Step 1031.4: 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 is iteratively determined on the intersection line segment using the bisection method; wherein the third overlapping 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 and the target overlapping area meet the preset difference requirements.

[0085] Sampling is performed at the starting and ending points AB of the current intersection line segment, and the overlapping area between the calculated points A and B and the drum-shaped section generated by the current path point is checked. If the preset target overlapping area is within the overlapping area corresponding to the calculated starting and ending points, the offset path point is obtained through binary iteration.

[0086] When it is determined that there must be an offset path point on the current intersection line segment, the starting and ending points of the intersection line segment are used as the initial iteration points, and the offset path points that meet the target overlapping area requirements are quickly obtained through binary search.

[0087] Step 1032: Connect the offset path points corresponding to each path point on the current path to obtain the offset path of the current path.

[0088] Step 1033: Update the offset path to the current path.

[0089] End the path offset and connect the separated path points to obtain a continuous surface manufacturing path.

[0090] Step 104 : Connect all the offset paths end to end at adjacent positions to obtain a three-dimensional printing path, that is, to obtain a final continuous curved surface manufacturing path.

[0091] In one embodiment, in order to further clarify the appropriate end path offset, after step 1031.3, respectively calculating the first overlapping area and the second overlapping area of ​​the drum-shaped section created based on the two endpoints of the intersection line segment and the drum-shaped section created based on the current path point, Figure 1 The method also includes:

[0092] If the preset target overlapping area is between the first overlapping area and the second overlapping area, and the offset path point corresponding to the current path point cannot be iteratively obtained on the intersection line segment using the bisection method, it means that the boundary has been reached, the path offset is completed, and the loop is exited.

[0093] Figure 8 This is a schematic diagram of the printing effect of the surface model to be printed in an embodiment of the present invention, based on Figure 7 The final path generated is used for manufacturing simulation, and the results are as follows Figure 8 As shown, it can be seen that the cladding is uniform and the shape meets the requirements. It is predicted that high-quality 3D printed surfaces can be manufactured.

[0094] Figure 9 FIG is a specific example of a method for generating a three-dimensional printing path for a curved surface according to an embodiment of the present invention, and shows a specific example of a path offset. Figure 9As shown in the figure, in this method: a target overlap area STarget is given in advance; then the boundary of the mesh surface is selected as the initial path, and a calculation method for the assumed offset direction f is set; when it is determined that f is a valid offset direction, the subscript i = 0 is initialized, and it is further determined whether the path i is empty. If it is not empty, j = 0 is initialized, and it is determined whether j < paths[i].size(). If so, the intersection line segment is obtained according to the method shown in Figure 1 The offset path points are determined by the bisection method until the offset of all paths is completed. Here, paths[i].size() represents the number of path points in the current path to be offset. Therefore, j is initialized to 0 and continuously increased until it is equal to paths[i].size() and exits the loop. In fact, it is traversing all the path points of the current path i and performing offsets.

[0095] In summary, the embodiment of the present invention proposes a more reasonable offset basis for the three-dimensional printing surface path - the equal overlap area offset basis. In the embodiment of the present invention, when the overlap area is equal to the air raid area, the material cladding can achieve uniform filling without under - or over - stacking. Selecting the overlap area by this method can predictably reduce the surface roughness of the manufactured surface and improve the mechanical properties and quality of the manufactured surface. The method of directly performing path offset on the discrete polygon surface in this method does not depend on the geometric features of the continuous surface, expands the available range of path point offset, improves the robustness and reliability of path generation, and can directly control the density of the material cladding in the three - dimensional printing manufacturing of the surface and ensure its uniform stacking at the same time.

[0096] In the embodiment of the present invention, a three - dimensional printing path generation device for a surface is also provided, as described in the following embodiments. Since the principle of the device for solving problems is similar to the three - dimensional printing path generation method for a surface, the implementation of the device can refer to the implementation of the three - dimensional printing path generation method for a surface, and the repeated parts will not be described again.

[0097] Figure 10 is a schematic diagram of the three - dimensional printing path generation device for a surface in the embodiment of the present invention, as shown in Figure 10 As shown, the device 1000 includes:

[0098] A mesh surface construction module 1001, configured to construct a mesh surface based on the surface model to be printed;

[0099] An initial path confirmation module 1002, configured to select the boundary of the mesh surface as the initial path; the initial path includes multiple path points;

[0100] A path offset module 1003, configured to record the initial path as the current path and perform a loop operation on the current path until multiple offset paths are obtained; The three-dimensional printing path determining module 1004 is configured to connect all the offset paths end to end at adjacent positions to obtain a three-dimensional printing path.

[0101] The above-mentioned cycle operation includes: Step 1: Perform the following steps 1.1 to 1.4 for each path point on the current path until the offset path point corresponding to each path point is obtained: Step 1.1: Construct a reference plane passing through the current path point and with the tangent vector direction of the current path as the normal direction; Step 1.2: Determine the intersection line segment between the reference plane and the mesh surface within the reference plane; Step 1.3: Calculate the first overlapping area and the second overlapping area of ​​the drum-shaped section created based on the two endpoints of the intersection line segment and the drum-shaped section created based on the current path point; the drum-shaped section is the cross-sectional shape of the 3D printing extruded filament; Step 1.4: If the preset target overlap area is between the first overlap area and the second overlap area, iteratively determine the offset path point corresponding to the current path point on the intersection line segment using a bisection method; wherein the third overlap area of ​​the drum section created based on the offset path point and the drum section created based on the current path point meets a preset difference requirement with the target overlap area; 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; Step 3: Update the offset path to the current path.

[0102] In one embodiment, the drum-shaped cross-section is in the shape of a racetrack, comprising two arc segments and a straight line segment in the middle;

[0103] The path offset module 1003 is specifically used for:

[0104] Calculate the overlapping area of ​​two drum sections using the following formula:

[0105] S overlap =S polygon +S extra ;

[0106] Among them, S overlap is the overlapping area, S polygon is the area of ​​the polygon, S extra The difference between the area of ​​the sector formed by the arc and the center of the circle and the area of ​​the polygon formed by the starting and ending points of the arc and the center of the circle.

[0107] In one embodiment, the path offset module 1003 is specifically configured to:

[0108] The first overlapping area and the second overlapping area of ​​the drum section created by any point on the straight line segment with the two end points of the intersecting line segment as the drum section and the drum section created by any point on the straight line segment with the current path point as the drum section are calculated respectively.

[0109] In one embodiment, the target overlapping area is set to the gap area between two adjacent extruded drum-shaped cross sections.

[0110] In one embodiment, the target overlap area is expressed as follows:

[0111] ;

[0112] Where S Target is the preset target overlapping area, R is the radius of the arc, and d is the distance between the centers of the two overlapping drum sections. .

[0113] In one embodiment, the path offset module 1003 is specifically configured to:

[0114] Determine the intersection line segment of the reference plane and the patch on the mesh surface where the current path point is located within the reference plane;

[0115] After respectively calculating the first overlapping area and the second overlapping area of ​​the drum-shaped section created based on the two endpoints of the intersection line segment and the drum-shaped section created based on the current path point, if the pre-set target overlapping area is not between the first overlapping area and the second overlapping area, determine the intersection line segment of the reference plane and the next face of the face where the current path point is located on the grid surface within the reference plane; one of the two endpoints of the intersection line segment is on the next face.

[0116] An embodiment of the present invention further provides a computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the above-mentioned surface-oriented three-dimensional printing path generation method when executing the computer program.

[0117] An embodiment of the present invention further provides a computer-readable storage medium storing a computer program. When the computer program is executed by a processor, the computer program implements the above-mentioned method for generating a curved surface-oriented three-dimensional printing path.

[0118] An embodiment of the present invention further provides a computer program product, which includes a computer program. When the computer program is executed by a processor, it implements the above-mentioned method for generating a three-dimensional printing path for a curved surface.

[0119] In an embodiment of the present invention, a direct offset basis for generating a three-dimensional printing surface path is proposed. If a preset target overlapping area is between a first overlapping area and a second overlapping area, the offset path point corresponding to the current path point is iteratively determined on the intersection line segment by bisection; wherein the third overlapping 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 and the target overlapping area meet the preset difference requirement, that is, the equal overlapping area offset basis. In this method, it is believed that when the overlapping area is equal to the preset target overlapping area, the material cladding can achieve uniform filling without under- or over-accumulation. Through the embodiment of the present invention, the density of the material cladding for three-dimensional printing of the surface can be directly controlled while ensuring its uniform accumulation, which can reduce the roughness of the manufactured surface and improve the mechanical properties and quality of the manufactured surface.

[0120] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Thus, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0121] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowcharts and / or block diagrams, as well as combinations of processes 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 device to produce 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 flowcharts and / or block diagrams. 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.

[0122] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0123] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0124] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for generating a three-dimensional printing path for a curved surface, characterized in that: include: Construct a mesh surface based on the surface model to be printed; Select the boundary of the mesh surface as the initial path; The initial path includes a plurality of path points; The initial path is recorded as the current path, and the following steps 1 to 3 are repeated for the current path until multiple offset paths are obtained: Step 1: Perform the following steps 1.1 to 1.4 for each path point on the current path until the offset path point corresponding to each path point is obtained: Step 1.1: Construct a reference plane passing through the current path point and with the tangent vector direction of the current path as the normal direction; Step 1.2: Determine the intersection line segment between the reference plane and the mesh surface within the reference plane; Step 1.3: Calculate the first overlapping area and the second overlapping area of ​​the drum-shaped section created based on the two endpoints of the intersection line segment and the drum-shaped section created based on the current path point; the drum-shaped section is the cross-sectional shape of the 3D printing extruded filament; Step 1.4: If the preset target overlapping area is between the first overlapping area and the second overlapping area, iteratively determine the offset path point corresponding to the current path point on the intersection line segment using a bisection method; wherein a third overlapping 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 and the target overlapping area meet a preset difference requirement; 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; Step 3: Update the bias path to the current path; All offset paths are connected end to end at adjacent positions to obtain a three-dimensional printing path.

2. The method according to claim 1, wherein The drum-shaped cross section is in the shape of a runway, comprising two arc segments and a straight line segment in the middle; The first overlapping area and the second overlapping area of ​​the drum section created based on the two endpoints of the intersection line segment and the drum section created based on the current path point are calculated respectively, including: Calculate the overlapping area of ​​two drum sections using the following formula: S overlap =S polygon +S extra ; Among them, S overlap is the overlapping area, S polygon is the area of ​​the polygon, S extra The difference between the area of ​​the sector formed by the arc and the center of the circle and the area of ​​the polygon formed by the starting and ending points of the arc and the center of the circle.

3. The method according to claim 2, wherein The first overlapping area and the second overlapping area of ​​the drum section created based on the two endpoints of the intersection line segment and the drum section created based on the current path point are calculated respectively, including: The first overlapping area and the second overlapping area of ​​the drum section created by any point on the straight line segment with the two endpoints of the intersecting line segment as the drum section and the drum section created by any point on the straight line segment with the current path point as the drum section are calculated respectively.

4. The method according to claim 2, wherein The target overlapping area is set as the gap area between two adjacent extruded drum sections.

5. The method according to claim 4, wherein The target overlap area is expressed as follows: ； Where S target is the preset target overlapping area, R is the radius of the arc, and d is the distance between the centers of the two overlapping drum sections. .

6. The method according to claim 1, wherein Determine the intersection line segment between the reference plane and the mesh surface within the reference plane, including: Determine the intersection line segment of the reference plane and the patch on the mesh surface where the current path point is located within the reference plane; After respectively calculating the first overlapping area and the second overlapping area of ​​the drum-shaped section created based on the two endpoints of the intersection line segment and the drum-shaped section created based on the current path point, the method further includes: If the preset target overlapping area is not between the first overlapping area and the second overlapping area, determine the intersection line segment between the reference plane and the next face of the face where the current path point is located on the grid surface within the reference plane; one of the two endpoints of the intersection line segment is on the next face.

7. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the computer program, the method according to any one of claims 1 to 6 is implemented.

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

9. A computer program product, characterized in that The computer program product comprises a computer program, and when the computer program is executed by a processor, the method according to any one of claims 1 to 6 is implemented.

Images