A path planning method of a 5-axis 3D printer

Abstract

The application belongs to the field of industrial manufacturing, and discloses a path planning method of a 5-axis 3D printer, which comprises a representation method of a random shape entity, a nozzle direction constraint method on a contour, an entity filling path planning method and a sampling interpolation method. The representation method of the random shape entity extracts shape data of a CAD model of the random shape entity, decomposes the model into constituent surfaces and edges, and determines the order and parameter direction of each constituent surface. The nozzle direction constraint method on the contour adopts a side tangent direction and a transition surface normal direction, a gradually deformed transition layer and adaptive material extrusion. The entity filling path planning method selects the last deposition layer to coincide with the top surface, designs a filling layer, fuses the base and the top surface by using a surface transition concept, and generates an internal filling path. The sampling interpolation method samples and interpolates a path according to position, and converts the path into G-code to obtain a printing path. The application can eliminate step effects and internal voids, reduce non-feeding movements, and support complex structures without the need for support.

Description

Technical Field

[0001] This invention belongs to the field of industrial manufacturing technology, specifically a path planning method for a 5-axis 3D printer. Background Technology

[0002] Since its inception in the 1980s, additive manufacturing (AM), or 3D printing, has continuously evolved. Additive manufacturing involves depositing material layer by layer along a path generated from a computer-aided design (CAD) model. A wide variety of materials, from flexible polymers to strong metals, can be manufactured using additive manufacturing. The most common additive manufacturing method is fused deposition modeling (FDM) or fused filament fabrication (FFF), which relies on the ductility of thermoplastics at low temperatures to deposit molten material to form solid parts. However, AM still has limitations in demanding industrial production environments.

[0003] First, the need for support structures: During additive manufacturing, due to the layer-by-layer deposition of materials, support structures are required to support the upper layers and prevent the parts from deforming or collapsing. These support structures need to be manually removed after manufacturing, which increases manufacturing costs and time.

[0004] Second, poor surface quality: Traditional additive manufacturing methods use parallel planes or offset surfaces to intersect with the CAD model, without considering the shape of the part. This rigid layering method leads to a stepped effect on the surface, affecting the accuracy and surface quality of the part.

[0005] Third, toolpath inefficiency: Traditional additive manufacturing methods usually only consider the parallel direction of the tool and do not make full use of the advantages of five-axis machining, resulting in low toolpath efficiency, which affects manufacturing efficiency and quality.

[0006] Fourth, insufficient load-bearing capacity: Because additive manufacturing involves layer-by-layer material deposition, its mechanical properties and load-bearing capacity may not be as good as those of traditional manufacturing methods. This may limit the application areas and functions of additively manufactured parts. Summary of the Invention

[0007] This invention addresses the aforementioned problems by proposing a path planning method for a 5-axis 3D printer. A novel 5-axis path planning model is presented, which takes into account the surface contours of conformal solid parts, preventing the staircase effect from affecting the outer shell. It reduces repetitive paths and nozzle constraints, offering a new process planning method to overcome obstacles in additive manufacturing. This invention addresses some of the frustrations of additive manufacturing by exploring new methods for model representation, geometric calculation, and path planning.

[0008] The technical solution adopted by the present invention to solve the above technical problems is as follows.

[0009] A path planning method for a 5-axis 3D printer includes a method for representing conformal solids, a method for constraining nozzle directions on the contour, and a method for planning solid filling paths. The conformal surface layer cutting method is implemented through a conformal surface layer cutting module, and the three-dimensional spatial path planning method is implemented through a three-dimensional spatial path planning module.

[0010] The 5-axis 3D printer has two additional degrees of freedom, generated by the rotation and tilting of the print bed. The print bed rotates about the C-axis, and its rotation is controlled by a motor attached to the bed platform base. The entire print bed rotates about the B-axis, and its tilting is controlled by a motor connected to a belt on the side of the print bed.

[0011] Furthermore, the representation of the conformal entity is performed using boundary representation (B-rep), which includes a set S(u, v) of trimmed non-uniform rational B-spline (NURBS) surfaces, edges, and vertices;

[0012] The method for representing conformal entities decomposes the conformal entity model into constituent surfaces and edges: the CAD model of the conformal entity is decomposed into its constituent surfaces and edges.

[0013] The conformal solid model determines the parameter orientation of the surfaces according to a specific order. The parameter orientation of the top surface T(u, v) and the bottom surface B(u, v) matches the material deposition direction. The side surfaces (S1, S2, S3, ...) are enumerated starting from the parameter origin edge in a counterclockwise direction, and the v direction of the boundary side surfaces is aligned with the additive direction.

[0014] Furthermore, the nozzle direction constraint method on the contour adopts side tangent direction constraint and transition surface normal direction constraint. The side tangent direction constraint keeps the nozzle direction tangent to the side, and the transition surface normal direction constraint keeps the nozzle direction normal to the filling surface and the top surface.

[0015] The nozzle orientation constraint method changes the local nozzle orientation through two degrees of freedom of the print bed of a 5-axis 3D printer;

[0016] The transition surface is a gradually deforming transition layer: during the process of filling the model to the top surface, a gradually deforming transition layer is used so that the path gradually changes from the reference surface to the top surface.

[0017] The transition layer employs adaptive material extrusion: this variable thickness within the layer is achieved by utilizing the wire length extruded at each point. Conversely, variations in layer thickness are achieved by adjusting the material extrusion amount according to the gaps in each layer's curve. That is, a diameter D... f Transformed into a grid with a rectangular cross-section and a width of w t , Δl i For the local layer thickness, from point (x) i y i, z i ) to point (x i+1 y i+1 , z i+1 ), wire extrusion length ΔE i ;

[0018]

[0019] The number of side layers is determined by the length of the longest curve from the bottom to the top edge and the maximum layer thickness, i.e., the length divided by the thickness. N points are evenly distributed along the common edge of each surface. The curves are the points mapped to connect all N layers on each side surface. On any side surface S(u, v), the parametric line of the mapping from point p1(u1, v1) to p2(u2, v2) will yield a curve C(t), 0 ≤ t ≤ 1. These provide the desired transition from the bottom to the top edge in the construction direction.

[0020] C(t)=S(u1+(u2-u1)t, v1+(v2-v1)t)

[0021] The nozzle orientation is determined by a combination of the lateral tangential direction constraint and the tangential direction of the curved path. Nozzle orientation tangent perpendicular to the local curve And perpendicular to the local surface normal

[0022] Furthermore, the entity filling path planning method adopts a topological internal filling mode, using a zigzag-shaped filling path.

[0023] The entity filling path planning method makes the intermediate layer surface L(u,v) = B(u,v) when n→0, and makes L(u,v) = T(u,v) when n→N.

[0024] The described solid-filling path planning method integrates the base and top surfaces using the concept of surface transition, establishing a one-to-one correspondence. A suitable transition layer is generated between the two surfaces using linear combination or linear deformation methods to achieve a smooth transition. The transition layer is denoted as L′(u, v).

[0025]

[0026] The entity filling path planning method maps the filling path onto the surface through the generation of network curves (NCs). These paths can generate continuous 3D curved paths on the surface, providing accurate path information for subsequent G-code processing.

[0027] The described solid-filling path planning method is applicable to composite models composed of multiple free-form models. Each independent model part can be manufactured sequentially, and the corresponding path planning strategy can be applied.

[0028] The present invention has the following beneficial effects:

[0029] 1. The present invention provides a path planning method for a 5-axis 3D printer, which eliminates or significantly reduces the step effect by optimizing path planning and filling strategy, thereby obtaining a smoother surface quality.

[0030] 2. The present invention provides a path planning method for a 5-axis 3D printer, which can improve manufacturing speed and reduce manufacturing time by reducing non-feeding motion and optimizing filling strategy.

[0031] 3. The present invention provides a path planning method for a 5-axis 3D printer, which can fully fill the internal space of the model by designing an appropriate filling path and implementing a suitable tool direction.

[0032] 4. The present invention provides a path planning method for a 5-axis 3D printer. Through reasonable path planning and filling strategies, it is possible to manufacture complex conformal solid models and achieve high-quality manufacturing of both the internal and external parts. Attached Figure Description

[0033] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof.

[0034] In the attached diagram:

[0035] Figure 1 This is a schematic diagram of the structure of the 5-axis 3D printer of the present invention;

[0036] Figure 2 This is a flowchart of the method of the present invention;

[0037] Figure 3 This is a flowchart of the CAD model representation of the present invention as an organized connected surface;

[0038] Figure 4 This is a flowchart of the algorithm for generating 3D curve paths from the side surface of the present invention;

[0039] Figure 5 This is a flowchart of the path planning for the filled surface according to the present invention;

[0040] Figure 6 This is a flowchart of the gradient line generation process of the present invention;

[0041] Figure 7This is a schematic diagram of the surface alignment and arrangement of the conformal solid model of the present invention;

[0042] Figure 8 This is a comparison diagram between the method of the present invention and the traditional planar slicing method;

[0043] Figure 9 This is a schematic diagram of the side contour path generation of the present invention.

[0044] Figure 10 This is a schematic diagram of the side path nozzle direction of the present invention;

[0045] Figure 11 This is a schematic diagram of the layer profile obtained by mixing the top and bottom surfaces according to the present invention;

[0046] Figure 12 This is a schematic diagram of the path generation for the fill transition layer in this invention;

[0047] Figure 13 This is a schematic diagram of the composite model sample of the present invention.

[0048] In the diagram: 1. Print head positioning motor; 2. Gantry; 3. Extrusion motor; 4. Print head; 5. Print bed; 6. Print bed tilting motor; 7. Print bed rotation motor; 8. Nozzle; 9. Synchronous belt; 10. Slide rail. Detailed Implementation

[0049] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0050] like Figure 1 As shown, Figure 1The design of a 5-axis 3D printer and its gantry 2 structure supporting and positioning the print head 4 are shown. Sliders connected to each slide rail 10 are vertically positioned by a timing belt 9, and the slides are connected to this timing belt and controlled by a print head positioning motor 1 above each slide rail 10. The positions of the slides on the three slide rails 10 collectively determine the position of the print head 4. An extrusion motor 3 injects filament into the interior of the print head 4, where it is heated and deposited within the nozzle 8. This 3D printer has two additional degrees of freedom generated by the rotation and tilting of the print bed 5. Giving these two additional rotational degrees of freedom to the print bed 5 instead of the print head 4 avoids additional loads on the print head 4, and keeping the print head 4 aligned with the direction of gravity facilitates material deposition. The rotation of the print bed 5 about the C-axis is controlled by a print bed rotation motor 7 attached to the base of the print bed 5. The tilting of the print bed about the B-axis is controlled by a print bed tilting motor 6 connected to a belt on the side of the print bed 5.

[0051] Path planning for 5-axis 3D printers includes methods for representing conformal solids, methods for constraining nozzle orientation on contours, and methods for solid infill path planning. For example... Figures 2 to 5 As shown, the method steps are as follows:

[0052] Step 1: Load the CAD model using CAD software (such as Rhinoceros) (file format STEP, IGES, or Rhinoceros);

[0053] Step 2: Determine if the model is a composite model. If so, divide the model into a combination of several single conformal entities, such as... Figure 13 As shown, the composite model is divided into four parts: 1, 2, 3, and 4; otherwise, you can directly proceed to step 3 to perform subsequent operations.

[0054] Step 3: Determine if the model is a solid. If so, establish a script environment to access its shape data and decompose the CAD model to extract its constituent surfaces and edges. The extracted surfaces are NURBS (Non-Uniform Rational B-Splines) surfaces, defined by parametric control points and possessing parameter domains and shape attributes. Otherwise, proceed directly to Step 4 for subsequent operations.

[0055] Step 4: The CAD software's scripting environment automatically flips and reverses the parameters of the extracted surfaces to ensure that the surfaces face the same direction.

[0056] Step 5: Determine whether the surface edge coincides with the boundary and other parametric lines, that is, whether the edges of the surface are connected to each other. If they do, extract the surface; otherwise, report an error and exit.

[0057] Step Six: Adjust the parameters of the top, bottom, and side surfaces to align them in the additive manufacturing direction. Adjust the parameter directions of the top surface T(u, v) and the bottom surface B(u, v) to be perpendicular to the additive manufacturing direction. Select the v parameter direction as the additive manufacturing direction for the side surfaces. Enumerate the side surfaces and label them in a counter-clockwise order starting from the parameter origin edge (e.g., S1, S2, S3, etc.). Figure 7 As shown.

[0058] Step 7: Save the representation file of the conformal solid model;

[0059] Step 8: Sidewall path planning. For example... Figure 9 As shown;

[0060] a. After aligning the curved surfaces according to the aforementioned conventions, determine the required number of layers. The number of layers (N) can be calculated by dividing the length by the thickness, by determining the length of the longest curve from the bottom to the top edge and using the target maximum layer thickness;

[0061] b. Distribute N points evenly along the common edge of each surface. For all N layers, connect two points on the side.

[0062] c. For Figure 9 The parametric lines mapping from point p1(u1, v1) to point p2(u2, v2) on the surface S(u, v) shown generate curves C(t), where 0 ≤ t ≤ 1. These curves may differ from the isoparametric lines of the surface, but they form a transition from the bottom to the top edge.

[0063] C(t)=S(u1+(u2-u1)t,v1+(v2-v1)t)

[0064] d. Nozzle direction The nozzle direction is determined by a nozzle orientation constraint method on the described profile. The nozzle direction is perpendicular to the ideal tangent direction of the local curve. Similarly, this method also determines the nozzle direction. The constraint is perpendicular to the direction of the local surface normal. like Figure 10 As shown;

[0065]

[0066] Step 9: Fill layer path planning. For example... Figure 12 As shown;

[0067] a. After aligning the surfaces according to the aforementioned conventions, determine the required number of layers. The number of layers (N) can be calculated by dividing the length by the thickness, by determining the length of the longest curve from the bottom to the top edge and using the target maximum layer thickness; extract the network curves of the bottom surface B(u, v) and the top surface T(u, v);

[0068] b. Distribute N points evenly along the common edge of each surface. For all N layers, connect two points on the side to form the contour of each layer; generate the surface of the transition layer by blending the bottom and top surfaces. The blending function L(u, v) is initially defined by establishing a linear relationship between the two surfaces;

[0069]

[0070] c. For each layer, the blending function L(u, v) may not lie on its exact contour. The exact contour is extracted directly from the boundary surface as the boundary of the new layer surface, i.e., curves L′(u, v0), L′(u1, v), L′(u, v1), L′(u, v0). The displacement vector d of the surface point located on the isoparametric curve in the u-direction is obtained by interpolation between the determinable displacement vectors L′(u, v0)-L(u, v0) and L′(u, v1)-L(u, v1). u Similarly, the displacement vector d of the surface point located on the isoparametric curve in the v-direction can be obtained (u, v). v (u, v), such as Figure 11 As shown;

[0071]

[0072] The displacement d(u, v) is calculated using a weighted average of the two values, where γ and (1-γ) represent the displacement vector weights in the u and v directions, respectively.

[0073] Finally, a new layer surface is constructed through linear combination or linear deformation, and a displacement vector is applied to the new layer surface to transfer it from the original surface to the new surface L′(u, v). The displacement vector is obtained by linear interpolation of the corresponding displacement vector.

[0074]

[0075] d. For each layer, a zigzag fill path is generated on the parameter domain of the surface, similar to traditional layer-by-layer slicing, with the zigzag direction alternating between layers.

[0076] e. Map the path onto each surface layer to obtain the 3D curved path on each surface layer, forming the final nozzle path.

[0077] The direction of the nozzle is determined by the tangent of the contour path of each side layer. The nozzle direction from the bottom layer to the top layer is perpendicular to the surface of each layer.

[0078] Step 10: The shape changes of the paths obtained in steps 8 and 9 within the same layer are caused by the changes in the gaps between adjacent curves. Only when the gaps between adjacent curves change will the shape of the entire layer change; that is, the shape of the curves will gradually deform from the bottom to the top. If the gaps between adjacent curves remain constant, the shape of the same layer will also remain constant. Therefore, during the printing process, in order to achieve complex geometric shapes and transition effects, the shape of the filament extruded by the nozzle must change with the gaps between adjacent curves.

[0079] Step 11: Based on the constant material volume and local layer thickness, calculate the material extrusion length at each point. That is, the length of a diameter D. f Transformed into a grid with a rectangular cross-section and a width of w t , Δl i For the local layer thickness, from point (x) i y i , z i ) to point (x i+1 y i+1 , z i+1 ), wire extrusion length ΔE i ;

[0080]

[0081] Step 12: The material extrusion length is added to the path, and the material extrusion rate varies according to the gap variation;

[0082] Step 13: Path points are sampled at their locations. The interpolator calculates the timestamp for each location point based on the set location intervals and the geometric characteristics of the path curve.

[0083] Step 14: Determine if the path configuration for all parts is complete. If yes, generate the G-code for the actual printing path; otherwise, switch to the next conformal solid model, ensuring the bottom surface overlaps seamlessly with the top surface of the previous model, and continue from Step 3.

[0084] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0085] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A path planning method for a 5-axis 3D printer, characterized in that: This includes methods for representing conformal entities, methods for constraining nozzle directions on contours, and methods for planning entity filling paths. The conformal surface slicing method is implemented through the conformal surface slicing module, and the three-dimensional spatial path planning method is implemented through the three-dimensional spatial path planning module. The representation of the conformal entity uses boundary representation (B-rep), which includes a set of trimmed non-uniform rational B-spline (NURBS) faces, edges, and vertices. ; The method for representing conformal entities decomposes the conformal entity model into constituent surfaces and edges: the CAD model of the conformal entity is decomposed into its constituent surfaces and edges; The conformal solid model determines the parameter orientation of the surface according to a specific order, top surface and bottom The parameter orientation matches the material deposition orientation, side surface Starting from the parameter origin edge, enumerate in a counter-clockwise direction, and align the v direction of the boundary side with the additive direction; The nozzle direction constraint method on the contour adopts side tangent direction constraint and transition surface normal direction constraint. The side tangent direction constraint keeps the nozzle direction tangent to the side, and the transition surface normal direction constraint keeps the nozzle direction normal to the filling surface and the top surface. The nozzle orientation constraint method changes the local nozzle orientation through two degrees of freedom of the print bed of a 5-axis 3D printer; The transition surface is a gradually deforming transition layer: during the process of filling the model to the top surface, a gradually deforming transition layer is used so that the path gradually changes from the reference surface to the top surface. The transition layer employs adaptive material extrusion: this variable thickness within the layer is achieved by utilizing the wire length extruded at each point, and conversely, the thickness variation within the layer is achieved by adjusting the material extrusion amount according to the gap of each layer's curve, i.e., a diameter... Transformed into a grid with a rectangular cross-section, the width is... , For local layer thickness, from point Time Wire extrusion length ; The number of side layers is determined by the length of the longest curve from the bottom to the top edge and the maximum layer thickness, i.e., the length divided by the thickness. N points are evenly distributed on the common edge of each surface, and the curve is the discovery point mapped to connect all N layers of each side surface. On any side surface Up, from point arrive The mapping parameter line will produce a curve , 0≤t≤1, they provide the desired transition from the bottom to the top edge in the construction direction, The nozzle direction is determined by a combination of the lateral tangential direction constraint and the tangential direction of the curved path. tangent perpendicular to the local curve And perpendicular to the local surface normal ； The entity filling path planning method employs a topology-internal filling mode, using a zigzag-shaped filling path. The entity filling path planning method in... At that time, the surface of the intermediate layer ,exist At that time, The solid filling path planning method, through the concept of surface transition, merges the base and top surfaces, establishing a one-to-one correspondence. Using linear combination or linear deformation methods, a suitable transition layer is generated between the two surfaces to achieve a smooth surface transition. The transition layer is represented as... , ； in, This is the lower bound of the direction of the u parameter. Let u be the upper bound of the direction of the parameter u. This is the lower bound of the direction of the v parameter. The upper bound of the v parameter direction is given by γ, which is the interlayer interpolation coefficient. The value range is γ∈[0,1], and it varies uniformly from the bottom to the top as the number of layers n increases. When γ=0, the transition layer is the base surface, and when γ=1, the transition layer is the top surface. The solid filling path planning method maps the filling path onto the surface through the generation of network curves. These paths can generate continuous 3D curve paths on the surface, providing accurate path information for subsequent G-code. The solid filling path planning method is suitable for composite models composed of multiple free-form models. Each independent model part can be manufactured in sequence, and the corresponding path planning strategy can be applied. Side paths and solid fill paths are interpolated by position sampling. The path is divided into a series of points with fixed position intervals, and each point has corresponding position coordinates.

2. A 5-axis 3D printer, used to execute the path planning method for the 5-axis 3D printer of claim 1, characterized in that: The 5-axis 3D printer has two additional degrees of freedom generated by the rotation and tilt of the print bed. The print bed rotates about the C-axis, which is controlled by a print bed rotation motor attached to the bed platform base. The entire print bed rotates about the B-axis, and its tilt is controlled by a belt connected to the side of the print bed, which is controlled by a print bed tilt motor.

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