An integrated construction method for additive manufacturing support structure and printing trajectory thereof

Abstract

The present invention discloses an integrated construction method for an additive manufacturing support structure and its printing trajectory. The support structure is expressed in a mixed explicit and implicit manner. Compared with the explicit expression in existing commercial software, the present invention can greatly reduce the amount of model data and shorten the model generation and rendering time. In addition, compared with explicit models, especially the STL format patch models used in existing additive manufacturing technologies, the present invention can carry model feature information when planning the printing trajectory, which facilitates the optimization of the printing trajectory and process parameters based on the topological features of the model.

Description

Technical Field

[0001] The present invention relates to the field of additive manufacturing technology, and in particular to an integrated construction method of an additive manufacturing support structure and a printing track thereof. Background Art

[0002] Additive Manufacturing (AM) technology, which forms three-dimensional objects by adding material layer by layer, is suitable for the fabrication of complex parts and has widespread application in aerospace, biomedical, automotive, and other fields. However, due to the limitations of the layer-by-layer stacking method, overhanging structures with large angles are prone to collapse during the molding process. Therefore, during pre-processing, such structures often require the addition of additional support structures based on molding constraints. Common support structures include conical supports, tree supports, cross supports, thin-wall supports, and lattice supports. Existing methods for adding support structures are based on a 3D explicit model, such as an STL model of the part. A series of geometric operations are then performed to achieve the 3D shape of the support structure. The support structure is then sliced ​​and filled together with the model to produce the final printing trajectory file. However, this method is computationally intensive and cumbersome, and the manufacturability of the supports cannot be guaranteed. This imposes additional pre-processing computational costs and production risks on AM service providers. Therefore, a support structure that can guarantee manufacturability and a fast and reliable support structure trajectory construction method are needed.

[0003] Therefore, an integrated construction method of an additive manufacturing support structure and its printing trajectory was developed to solve the above problems. Summary of the Invention

[0004] The purpose of the present invention is to design an integrated construction method of an additive manufacturing support structure and its printing trajectory in order to solve the above problems.

[0005] The present invention achieves the above-mentioned purpose through the following technical solutions:

[0006] An additive manufacturing support structure includes an explicit support structure and an implicit support structure, wherein the explicit support structure is a solid form model, and the implicit support structure is a non-solid lattice support. The implicit support structure includes a support construction domain and a lattice structure feature, wherein the support construction domain is a display expression, and the lattice structure feature is a parameterized implicit expression, namely:

[0007] S=S1∪S2

[0008] S2=Ω2∩S_P

[0009] Among them, S is the support structure, S1 is the explicit support structure, S2 is the implicit support structure, Ω2 is the implicit support construction domain, and S_P is the implicitly expressed lattice support structure feature.

[0010] An integrated construction method for an additive manufacturing support structure printing track comprises the following steps:

[0011] S1. Construct the overall support structure domain and create a three-dimensional solid model of the support structure area;

[0012] S2, separating the solid wall support area and the non-solid support area; including: first configuring the wall support parameters; then performing a shell operation on the 3D model in S1, with the shell thickness being t+t0, the inner core area being the implicit support construction domain Ω2, and the outer shell area being the solid wall support area Ω1;

[0013] S3. Create solid wall support; including:

[0014] a. Pre-process the solid wall support region Ω1 obtained in S2 by removing independent regions with a volume smaller than V0. Then, offset the processed region by t0 / 2 on each side to create a wall with a thickness of t.

[0015] b. According to the preset maximum length L of the wall max Interrupt the wall obtained in a and adjust it according to the hollow shape parameter PS a Hollow out the wall;

[0016] c. Set the shape of the contact point between the wall and the part;

[0017] S4. Create a non-solid lattice support, where the non-solid lattice support is expressed as an implicit model. That is, in the implicit support construction domain Ω2, a parameterized form is used to describe the lattice characteristics, but no specific explicit model is generated. Its expression is in the form of equations and parameters. The specific construction steps are:

[0018] a. Select lattice unit type LT from the lattice type database;

[0019] b. Set the lattice parameter LP corresponding to the lattice type LT;

[0020] c. Set the lattice pre-processing parameters LPP;

[0021] S5. Selecting printing trajectory process parameters from the process database, including the process parameter Solid_P for the solid wall support printing trajectory and the process parameter Non_Solid_P for the non-solid lattice support printing trajectory;

[0022] S6. Generate and optimize the support printing process trajectory; the specific steps are:

[0023] a. Plan the printing process trajectory of the solid support based on the solid wall support model and its printing trajectory process parameter Solid_P;

[0024] b. Generate non-solid support process trajectory based on the implicitly expressed model and the corresponding process parameter Non_Solid_P;

[0025] c. Sort the process trajectories.

[0026] The beneficial effects of the present invention are:

[0027] The present invention uses a support structure that is a hybrid of explicit and implicit expressions. Compared with the explicit expressions in existing commercial software, the present invention can greatly reduce the amount of model data and shorten the model generation and rendering time. In addition, compared with explicit models, especially the STL format patch models used in existing additive manufacturing technologies, the present invention can carry model feature information when planning the printing trajectory, making it easier to optimize the printing trajectory and process parameters based on the topological features of the model. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a flow chart of the manufacturing method of the present invention;

[0029] Figure 2 is the model diagram to be supported in Example 1 of the present invention;

[0030] Figure 3 It is the overall support structure area in Example 1 of the present invention;

[0031] Figure 4 These are the solid wall support region (A) and the non-solid implicit lattice support region (B) in Example 1 of the present invention;

[0032] Figure 5 It is the hollow wall support structure in Example 1 of the present invention;

[0033] Figure 6 This is a rendering of the TPMS-Schwarz-P lattice support in Example 1 of the present invention;

[0034] Figure 7 is a rendering of the contour trajectory of the support structure and the solid model in Example 1 of the present invention;

[0035] Figure 8 This is a process trajectory diagram of the first layer of the support structure in Example 1 of the present invention. DETAILED DESCRIPTION

[0036] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings of the embodiments of the present invention. It should be understood that the described embodiments are only a portion of the embodiments of the present invention, not all of them. Generally, the components of the embodiments of the present invention described and illustrated in the drawings herein may be arranged and designed in a variety of different configurations.

[0037] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort shall fall within the scope of protection of the present invention.

[0038] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0039] In the description of the present invention, it should be understood that the terms "upper", "lower", "inside", "outside", "left", "right", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the inventive product is conventionally placed when in use, or are the orientations or positional relationships conventionally understood by those skilled in the art. These are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or component referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0040] Furthermore, the terms “first”, “second”, etc. are merely used for distinguishing descriptions and should not be understood as indicating or implying relative importance.

[0041] In the description of the present invention, it should also be noted that, unless otherwise expressly specified or limited, terms such as "disposed" and "connected" should be understood in a broad sense. For example, "connected" can mean a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can also mean internal communication between two components. Those skilled in the art will be able to understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0042] The specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0043] An additive manufacturing support structure includes an explicit support structure and an implicit support structure, wherein the explicit support structure is a solid form model, and the implicit support structure is a non-solid lattice support. The implicit support structure includes two parts: a support construction domain and a lattice structure feature. The support construction domain is a display expression, and the lattice structure feature is a parameterized implicit expression. That is:

[0044] S=S1∪S2

[0045] S2=Ω2∩S_P

[0046] Among them, S is the support structure, S1 is the explicit support structure, S2 is the implicit support structure, Ω2 is the implicit support construction domain, and S_P is the implicitly expressed lattice support structure feature.

[0047] In some embodiments, the implicit support construction domain Ω2 is an explicit CAD model.

[0048] In some embodiments, the structural features of the implicit support construction domain Ω2 are parameterized implicit models, and the structural features are selected from a lattice structure database whose support manufacturability has been verified.

[0049] like Figure 1 As shown, an integrated construction method for an additive manufacturing support structure printing track includes the following steps:

[0050] S1. Construct the overall support structure domain and create a three-dimensional solid model of the support structure area;

[0051] S2, separating the solid wall support area and the non-solid support area; including: first configuring the wall support parameters; then performing a shell operation on the 3D model in S1, with the shell thickness being t+t0, the inner core area being the implicit support construction domain Ω2, and the outer shell area being the solid wall support area Ω1;

[0052] S3. Create solid wall support; including:

[0053] a. Pre-process the solid wall support region Ω1 obtained in S2 by removing independent regions with a volume smaller than V0. Then, offset the processed region by t0 / 2 on each side to create a wall with a thickness of t.

[0054] b. According to the preset maximum length L of the wall max Interrupt the wall obtained in a and adjust it according to the hollow shape parameter PS a Hollow out the wall;

[0055] c. Set the shape of the contact point between the wall and the part;

[0056] S4. Create a non-solid lattice support, where the non-solid lattice support is expressed as an implicit model. That is, in the implicit support construction domain Ω2, a parameterized form is used to describe the lattice characteristics, but no specific explicit model is generated. Its expression is in the form of equations and parameters. The specific construction steps are:

[0057] a. Select lattice unit type LT from the lattice type database;

[0058] b. Set the lattice parameter LP corresponding to the lattice type LT;

[0059] c. Set the lattice pre-processing parameters LPP;

[0060] S5. Selecting printing trajectory process parameters from the process database, including the process parameter Solid_P for the solid wall support printing trajectory and the process parameter Non_Solid_P for the non-solid lattice support printing trajectory;

[0061] S6. Generate and optimize the support printing process trajectory; the specific steps are:

[0062] a. Plan the printing process trajectory of the solid support based on the solid wall support model and its printing trajectory process parameter Solid_P;

[0063] b. Generate non-solid support process trajectory based on the implicitly expressed model and the corresponding process parameter Non_Solid_P;

[0064] c. Sort the process trajectories to reduce jump distance and improve scanning efficiency.

[0065] In some embodiments, in step S1, the solid model of the overall support structure domain is a general CAD solid model, and the overall support structure domain is created in solid form or patch form; the CAD model formats include '.x_t', '.iges', '.step', '.STL' and '.obj', etc.

[0066] In some embodiments, in step S2, the configured wall support parameters include: wall thickness t, maximum wall support length L max , wall hollow shape parameters PS a .

[0067] In some embodiments, in step S2 , if a variety of lattices are required as non-solid supports, the non-solid regions need to be segmented and marked first.

[0068] In some embodiments, in step S3 , the shapes of the contact points between the wall and the component include sawtooth, cone point, cross, and surface shapes (full contact wall).

[0069] In some embodiments, in step S4 , the lattice cell type LT includes TPMS, Scaffold, Foam, and Voronoi; the lattice parameters LP include a lattice cell size US, a lattice shape factor SF, and specific parameters of a specific lattice.

[0070] In some embodiments, in step S5, the process parameters Solid_P of the solid support printing track include laser power P, scanning speed v, and overlap spacing h; the process parameters Non_Solid_P of the non-solid support printing track include laser power P, scanning speed v, and overlap spacing h.

[0071] In some embodiments, in step S5 , when the non-solid support process trajectory is generated, its input is an implicit equation.

[0072] In some embodiments, in step S6, the specific steps of process trajectory planning of the solid wall support printing process trajectory are: first, the supported solid model is sliced ​​and layered, and then the sliced ​​polygons are filled with straight lines, and finally the straight lines are sorted and optimized; the specific steps of process trajectory planning of the implicitly expressed non-solid lattice support are: slice and layer the support construction domain, and then fill the sliced ​​polygons according to the implicit equations and lattice parameters of the lattice, and finally the filling trajectories are sorted.

[0073] The present invention can realize the rapid generation of the process trajectory of the support structure while ensuring the manufacturability requirements of the support structure and parts.

[0074] Example 1

[0075] An integrated construction method for printing tracks of additive manufacturing support structures is used to Figure 2 The support structure construction and printing process trajectory generation of the Ti6Al4V part shown are as follows:

[0076] S1. Construct the overall support structure domain. Select the area to be supported according to the 45° angle rule, then create a projection surface and stretch the projection area to generate a three-dimensional solid support structure domain, such as Figure 3 shown.

[0077] S2. Separate the solid wall support area and the non-solid support area. First, configure the wall support parameters, such as: set the wall thickness t = 1mm, the maximum wall support length Lmax = 5mm, and the wall hollow shape parameters PSa (shape: diamond; angle: 60°; side length: 2mm; interval: 5mm); then perform a shell extraction operation on the 3D model in S1, with the shell thickness t + t0 = 1.2mm. The core area is the non-solid implicit lattice support area, and the outer shell area is the solid wall support area. The two areas are as follows: Figure 4 shown.

[0078] S3. Create a solid wall support, specifically:

[0079] a. Pre-process the solid wall support area obtained in S2, remove independent areas with a volume smaller than V0 = 1 mm3, and then offset the processed area by t0 / 2 = 0.1 mm on each side to create a wall with a thickness of t = 1 mm;

[0080] b. According to the preset maximum wall length Lmax=5mm, the wall obtained in a is interrupted, and the wall is hollowed out according to the hollow shape parameter PSa, as shown in FIG. Figure 5 As shown;

[0081] c. Set the shape of the contact point between the wall and the part to a zigzag shape.

[0082] S4. Create a non-solid lattice support, where the non-solid lattice support is expressed as an implicit model, that is, a parametric form is used to describe the lattice features when generating a 3D display model. The specific construction steps are as follows:

[0083] a. Select the lattice cell type from the lattice type database: LT = 'TPMS–Schwarz-P';

[0084] b. Set the lattice parameters corresponding to the lattice type TPMS-Schwarz-P: lattice unit size US = 2 mm, shape factor SF = 0;

[0085] c. Set the lattice pre-processing parameters LPP (angle: LA = 0°; overlap region length: LR = 0 mm). The final implicit model equation is:

[0086]

[0087] To explain the structure more intuitively, Figure 6 An explicit model of the lattice is shown, but this application does not require the construction of such an explicit model; Figure 7 A rendering showing the overall support structure and the part's contour trajectory.

[0088] S5. Select the printing trajectory process parameters from the process database. Here, SLM technology is used for printing. The process parameters of the solid wall support printing trajectory are Solid_P (laser power: P = 120W; scanning speed: v = 1200mm / s; overlap interval h = 0.08mm), and the printing trajectory process parameters of the non-solid implicit lattice support are Non_Solid_P (laser power: P = 90W; scanning speed: v = 850mm / s).

[0089] S6. Generate and optimize the support printing process trajectory. The specific steps are as follows:

[0090] a. Plan the printing process trajectory of the solid support based on the solid wall support model and its printing trajectory process parameter Solid_P;

[0091] b. Generate a non-solid implicit lattice support process trajectory based on the implicitly expressed model and the corresponding process parameter Non_Solid_P;

[0092] c. Sort the process tracks, reduce the jump distance, improve the scanning efficiency, and generate the final printing process track. The printing process track of the first layer of the support is as follows: Figure 8 shown.

[0093] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. An integrated construction method for an additive manufacturing support structure printing track, characterized in that: The additive manufacturing support structure includes explicit support structure and implicit support structure. The explicit support structure is a solid form model, and the implicit support structure is a non-solid lattice support. The implicit support structure consists of two parts: the support construction domain and the lattice structure feature. The support construction domain is a display expression, and the lattice structure feature is a parameterized implicit expression, namely: ， ， Wherein, S is the supporting structure, For explicit support structures, Implicit support structure, Construct the domain for the implicit support, is the implicitly expressed lattice support structure feature; Implicit support construction domain is an explicit CAD model; Implicit support construction domain The structural features are implicit models expressed in a parameterized manner, and the structural features are selected from a lattice structure database whose support manufacturability has been verified; The integrated construction method for the printing track of the additive manufacturing support structure includes the following steps: S1. Construct the overall support structure domain and create a three-dimensional solid model of the support structure area; S2, separation of solid wall support area and non-solid support area; including: first configuring wall support parameters; then performing shell extraction operation on the 3D model in S1, with the shell thickness being t+t0, and the core area being the implicit support construction domain , the shell area is the solid wall support area ; S3. Create solid wall support; including: a. For the solid wall support area obtained in S2 Perform pre-processing to remove independent areas with a volume smaller than V0, then offset the processed areas by t0 / 2 on each side to create a wall with a thickness of t; b. According to the preset maximum length L of the wall max Interrupt the wall obtained in a and adjust it according to the hollow shape parameter PS a Hollow out the wall; c. Set the shape of the contact point between the wall and the part; S4. Create a non-solid lattice support, where the non-solid lattice support is an implicit model expression, that is, in the implicit support construction domain In , a parametric form is used to describe the lattice characteristics, but no specific explicit model is generated. Its expression is in the form of equations and parameters. The specific construction steps are: a. Select lattice unit type LT from the lattice type database; b. Set the lattice parameter LP corresponding to the lattice type LT; c. Set the lattice pre-processing parameters LPP; S5. Selecting printing trajectory process parameters from the process database, including the process parameter Solid_P for the solid wall support printing trajectory and the process parameter Non_Solid_P for the non-solid lattice support printing trajectory; S6. Generate and optimize the support printing process trajectory; the specific steps are: a. Plan the printing process trajectory of the solid support based on the solid wall support model and its printing trajectory process parameter Solid_P; b. Generate non-solid support process trajectory based on the implicitly expressed model and the corresponding process parameter Non_Solid_P; c. Sort the process trajectories.

2. The integrated construction method for an additive manufacturing support structure printing track according to claim 1, characterized in that: In step S1 , the solid model of the overall support structure domain is a general CAD solid model, and the overall support structure domain is created in a solid form or a surface form.

3. The integrated construction method for an additive manufacturing support structure printing track according to claim 1, characterized in that: In step S2, the configured wall support parameters include: wall thickness t, maximum wall support length L max , wall hollow shape parameters PS a .

4. The integrated construction method for an additive manufacturing support structure printing track according to claim 1, characterized in that: In step S3 , the shapes of the contact points between the wall and the component include sawtooth, cone point, cross, and surface shapes.

5. The integrated construction method for an additive manufacturing support structure printing track according to claim 1, characterized in that: In step S4 , the lattice cell types LT include TPMS, Scaffold, Foam, and Voronoi; the lattice parameters LP include the lattice cell size US, the lattice shape factor SF, and specific parameters of the specific lattice.

6. The integrated construction method for an additive manufacturing support structure printing track according to claim 1, characterized in that: In step S5 , the process parameters Solid_P of the solid support printing track include laser power P, scanning speed v, and overlap distance h; the process parameters Non_Solid_P of the non-solid support printing track include laser power P, scanning speed v, and overlap distance h.

7. The integrated construction method for an additive manufacturing support structure printing track according to claim 1, characterized in that: In step S6, the specific steps of process trajectory planning for the solid wall support printing process trajectory are: first, slice and layer the supported solid model, then fill the sliced ​​polygons with straight lines, and finally sort and optimize the straight lines; the specific steps of process trajectory planning for the implicitly expressed non-solid lattice support are: slice and layer the support construction domain, then fill the sliced ​​polygons according to the implicit equations and lattice parameters of the lattice, and finally sort the filling trajectories.

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