A method for generating a scanning path for laser additive manufacturing

Abstract

The present invention discloses a method for generating a scanning path for laser additive manufacturing, which relates to the technical field of additive manufacturing and aims to solve the problem of deformation caused by stress concentration during the printing of large-area parts. The method includes: obtaining the physical parameters of each sliced layer of the part and the diameter of the small-hole area; marking the sliced layers whose area, maximum length, and maximum width all meet the conditions based on the diameter of the small-hole area to obtain the marked sliced layers; partitioning the marked sliced layers according to the edge contour lines of the marked sliced layers and the diameter of the small-hole area to obtain small-hole areas evenly distributed within the marked sliced layers and linear areas other than the small-hole areas; performing path filling on the small-hole areas and the linear areas to obtain the scanning path corresponding to the marked sliced layer of the part; the small-hole areas are scanned after the linear areas are scanned. The method for generating a scanning path for laser additive manufacturing provided by the present invention is used to reduce stress concentration during the printing of large-area parts.

Description

Technical Field

[0001] The present invention relates to the technical field of additive manufacturing, and in particular to a method for generating a scanning path for laser additive manufacturing. Background Art

[0002] Selective laser melting (SLM) forming is one of the main methods of metal additive manufacturing. Based on the idea of discrete - stacking, a part is divided into several micron - thick thin layers from top to bottom. After the scanning path is planned for each layer, the laser melts the metal powder according to the scanning path, and the melted metal cools and forms to obtain the part. Selective laser melting has the advantages of no need for a mold, short processing cycle, and can realize the manufacturing of complex cavities and special - shaped structures, and has been widely used in the fields of aviation, aerospace, automotive, etc.

[0003] In recent years, the demand for additive manufacturing of large - sized parts has gradually increased. There are usually large - area solids in large - sized parts. When the laser scans on the large - area solid, it takes more time, which will cause the continuous accumulation of heat, resulting in thermal stress concentration, and then lead to the deformation of the part. When the large - area solid is a hanging structure, the deformation is particularly significant. The deformation of the additive - manufactured part or the warping of the printing surface may cause the scrapping of the part.

[0004] The scanning path is one of the important factors affecting SLM forming. The scanning path determines the melting and cooling sequence of the metal powder and affects the stress distribution during the printing process. The scanning method is usually internal scanning plus boundary contour scanning. The common internal scanning method is to regard the solid part of the part as one or several uniform regions, and each region is filled with serpentine lines or parallel lines inside, and then each region is scanned in sequence. If the part size area is too large, this scanning method is prone to stress concentration. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for generating a scanning path for laser additive manufacturing, which is used to solve the deformation problem caused by stress concentration during the printing of large - area parts.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] The present invention provides a method for generating a scanning path for laser additive manufacturing, including:

[0008] Obtaining the physical parameters of each sliced layer of the part and the diameter of the small - hole area; the physical parameters include the area, the maximum length, and the maximum width of the sliced layer;

[0009] Marking the sliced layer that satisfies the conditions for the area, the maximum length, and the maximum width based on the diameter of the small - hole area to obtain a marked sliced layer;

[0010] Partition the marked slice layer according to the edge contour line of the marked slice layer and the diameter of the small hole area, to obtain small hole areas evenly distributed within the marked slice layer and a linear area other than the small hole areas; the distance from the center point of the small hole area to the edge contour line is greater than or equal to 2 times the diameter of the small hole area, and the distance between the center points of adjacent small hole areas is within the range of three times to five times the diameter of the small hole area;

[0011] Perform path filling on the small hole areas and the linear area to obtain the scanning path corresponding to the marked slice layer of the part; the small hole areas are scanned after the linear area is scanned.

[0012] Compared with the prior art, the scanning path generation method for laser additive manufacturing provided by the present invention includes obtaining the physical parameters of each slice layer of the part and the diameter of the small hole area; marking the slice layer that meets the conditions for area, maximum length, and maximum width based on the diameter of the small hole area to obtain a marked slice layer; through marking, it can be ensured that only the large-area slice layers are subjected to subsequent partitioning processing, and the slice layers of non-large-area entities are not partitioned; partition the marked slice layer according to the edge contour line of the marked slice layer and the diameter of the small hole area to obtain small hole areas evenly distributed within the marked slice layer and a linear area other than the small hole areas; this partitioning method can greatly reduce the overlapping positions between regions, avoid problems of excessive local input and stress concentration caused by too many overlapping positions, and at the same time dividing the part into parts with small hole areas can make the printing deformation smaller. The small hole areas are scanned after the linear area is scanned, so that when the laser scans a certain layer, it first scans the linear area, reserves the small hole areas, and then scans the small hole areas, avoiding continuous scanning of a slice layer, resulting in heat accumulation, thereby reducing the risk of part deformation and cracking and effectively alleviating the problem of stress concentration.

[0013] Optionally, the maximum length of the marked slice layer is greater than or equal to 8 times the diameter of the small hole area, the maximum width of the marked slice layer is greater than or equal to 8 times the diameter of the small hole area, and the area of the marked slice layer is greater than or equal to the product of 16Π and the square of the diameter of the small hole area.

[0014] Optionally, the performing path filling on the small hole areas and the linear area to obtain the scanning path corresponding to the marked slice layer of the part includes:

[0015] Perform filling on the marked slice layer to obtain a plurality of filling paths;

[0016] Use the contour line of the small hole area to divide the plurality of filling paths to obtain the scanning path corresponding to the marked slice layer of the part; the scanning path corresponding to the marked slice layer includes a small hole area scanning path and a linear area scanning path.

[0017] Optionally, after performing path filling on the small hole area and the linear area to obtain the scanning path corresponding to the marked slice layer of the part, the following steps are further included:

[0018] Perform path filling on the slice layers of the part other than the marked slice layer to obtain the scanning path of the non-marked slice layer of the part. The filling method of the scanning path of the non-marked slice layer is the same as that of the scanning path of the linear area.

[0019] Optionally, after performing path filling on the small hole area and the linear area to obtain the scanning path corresponding to the marked slice layer of the part, the following steps are further included:

[0020] Determine whether the slice layer is a marked slice layer. If it is a marked slice layer, scan the linear area in the marked slice layer based on the scanning path of the linear area until all the linear areas in the marked slice layer are scanned; scan the small hole area in the marked slice layer based on the scanning path of the small hole area;

[0021] If the slice layer is not a marked slice layer, scan the slice layer according to the scanning path of the non-marked slice layer;

[0022] Scan the next slice layer until all slice layers are scanned to obtain the part.

[0023] Optionally, the scanning of the small hole area in the marked slice layer based on the scanning path of the small hole area includes:

[0024] Scan the first small hole area based on the scanning path of the small hole area until the first small hole area is scanned; when scanning the small hole area, only scan the filling path of the small hole area;

[0025] Perform scanning of the second small hole area until all small hole areas are scanned. The second small hole area and the first small hole area are adjacent small hole areas.

[0026] Optionally, the scanning path of the linear area is a parallel line or a serpentine line; the scanning of the next slice layer includes:

[0027] Rotate the scanning direction of the previous slice layer by 60° and then perform scanning of the slice layer.

[0028] Optionally, each slice layer of the part includes at least two slice layers of the part; the marked slice layer includes: determining the target slice layer in each slice layer based on the diameter of the small hole area; the target slice layer is the slice layer whose area, maximum length, and maximum width all meet the conditions;

[0029] Mark the target slice layer to obtain the marked slice layer.

[0030] Mark the target slice layer to obtain a marked slice layer.

[0031] Optionally, the shape of the small hole area is circular, elliptical, rectangular or triangular. Description of the Drawings

[0032] The drawings described herein are used to provide a further understanding of the present invention, and constitute a part of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention, and do not constitute an improper limitation of the present invention. In the drawings:

[0033] Figure 1 is a flowchart of a scanning path generation method for laser additive manufacturing provided by the present invention;

[0034] Figure 2 is a schematic diagram of a part printing surface provided by the present invention;

[0035] Figure 3 is a schematic diagram of a partition provided by the present invention;

[0036] Figure 4 is a schematic diagram of path filling provided by the present invention.

[0037] Reference Signs:

[0038] 1 - outer contour line, 2 - internal entity, 3 - linear area, 4 - small hole area. Detailed Embodiments

[0039] In order to facilitate a clear description of the technical solutions of the embodiments of the present invention, in the embodiments of the present invention, terms such as "first" and "second" are used to distinguish the same items or similar items with basically the same functions and effects. For example, the first threshold and the second threshold are only used to distinguish different thresholds, and do not limit their order. Those skilled in the art can understand that terms such as "first" and "second" do not limit the quantity and execution order, and terms such as "first" and "second" do not necessarily limit being different.

[0040] It should be noted that in the present invention, words such as "exemplary" or "for example" are used to represent examples, illustrations or explanations. Any embodiment or design solution described as "exemplary" or "for example" in the present invention should not be construed as being more preferred or having more advantages than other embodiments or design solutions. Rather, the use of words such as "exemplary" or "for example" is intended to present relevant concepts in a specific manner.

[0041] In the present invention, "at least one" means one or more, and "a plurality" means two or more. "And / or" describes the relationship between associated objects and indicates that three relationships can exist. For example, A and / or B can represent the situations of A existing alone, A and B existing simultaneously, and B existing alone, where A and B can be singular or plural. The character " / " generally indicates an "or" relationship between the associated objects before and after. "At least one (item)" or similar expressions refer to any combination of these items, including any combination of single item or plural items. For example, at least one (item) among a, b, or c can represent: a, b, c, the combination of a and b, the combination of a and c, the combination of b and c, or the combination of a, b, and c, where a, b, and c can be single or multiple.

[0042] With the wide application of additive manufacturing technology, the emergence of various new structural components and new technical fields have put forward higher requirements for additive manufacturing technology. In the conventional scanning method, the printing process of each layer is boundary contour scanning plus internal solid scanning. For parts with large areas, if the conventional scanning method is used entirely, problems such as cracking and deformation caused by stress concentration will occur.

[0043] To address the above problems, the present invention provides a method for generating a scanning path for laser additive manufacturing to optimize the printing process of large-area solids. The three-dimensional model is stratified according to the layer thickness, and the printing layers with large-area solids are marked, simply referred to as marked layers. The marked layer area is divided into a linear area and several small-hole areas. The small-hole areas are hole-shaped areas evenly distributed on the printing surface, and the linear area is the other area except the small-hole areas. During the process of generating the scanning path, first, each sliced layer after stratification is identified layer by layer. The sliced layer with a large-area solid is a marked sliced layer, otherwise it is an unmarked sliced layer. The entire printing surface of the unmarked sliced layer is regarded as a linear area without area division. By region division and setting the printing order of different regions, the problem of stress concentration during single-layer large-area printing is solved. The following will be described in conjunction with the accompanying drawings.

[0044] See Figure 1 , the present invention provides a method for generating a scanning path for laser additive manufacturing, and the method includes the following steps:

[0045] Step 101: Obtain the physical parameters of each sliced layer of the part and the diameter of the small-hole areas; the physical parameters include the area, maximum length, and maximum width of the sliced layer;

[0046] The sliced layers of the part are obtained by slicing the three-dimensional model of the part according to a preset layer thickness. The size of the diameter of the small-hole areas is set according to requirements. Whether a sliced layer is identified as a marked sliced layer is determined according to the diameter size of the small-hole areas.

[0047] Step 102: Based on the diameter of the small hole area, mark the slice layers whose area, maximum length, and maximum width all meet the conditions to obtain marked slice layers;

[0048] The maximum length of the marked slice layer is greater than or equal to 8 times the diameter of the small hole area, the maximum width of the marked slice layer is greater than or equal to 8 times the diameter of the small hole area, and the area of the marked slice layer is greater than or equal to 16Πd 2 , where d is the diameter of the small hole area, and the length and width are the dimensions in two mutually perpendicular directions in the slice layer. The limiting conditions of this marked slice layer are to identify the slice layers of large-area entities. The size of the area can be subjectively defined. The area, length, and width of the slice layer are related to the diameter of the small hole area. When the area of the slice layer is larger, the diameter of the small hole area is larger, and vice versa. This can ensure that the small hole area can appear on the printing surface of any area.

[0049] Step 103: Divide the marked slice layer according to the edge contour line of the marked slice layer and the diameter of the small hole area to obtain small hole areas evenly distributed in the marked slice layer and linear areas except the small hole areas;

[0050] The distance from the center point of the small hole area to the edge contour line is greater than or equal to 2 times the diameter of the small hole area, and the distance between the center points of adjacent small hole areas is in the range of three times to five times the diameter of the small hole area. The shape of the small hole area is circular, elliptical, rectangular, or triangular.

[0051] Step 104: Perform path filling on the small hole areas and the linear areas to obtain the scanning path corresponding to the marked slice layer of the part;

[0052] Specifically, first fill the marked slice layer to obtain multiple filling paths; the filling method can be parallel line filling, serpentine line filling, or other filling methods. Then use the contour line of the small hole area to divide the multiple filling paths to obtain the scanning path corresponding to the marked slice layer of the part; the scanning path corresponding to the marked slice layer includes the small hole area scanning path and the linear area scanning path.

[0053] The linear area scanning path is a parallel line or a serpentine line; the small hole area is scanned after the linear area scanning is completed. When scanning the marked slice layer, the laser first scans the linear area, and after the linear area is completely scanned, then the small hole area is scanned.

[0054] The scanning path generation method for laser additive manufacturing marks the sliced layers whose hole area meets the conditions for diameter, area, maximum length, and maximum width to obtain marked sliced layers; through marking, it can be ensured that only the large-area sliced layers are subjected to subsequent zoning processing, and the sliced layers of non-large-area entities are not zoned; according to the edge contour line of the marked sliced layer and the hole area diameter, the marked sliced layer is zoned to obtain uniformly distributed hole areas and linear areas except for the hole areas within the marked sliced layer; this zoning method can greatly reduce the overlapping positions between regions, avoid problems such as excessive local input and stress concentration caused by too many overlapping positions, and at the same time dividing the part into parts with hole areas can make the printing deformation smaller. The hole areas are scanned after the linear areas are scanned, so that when the laser scans a certain layer, it first scans the linear areas, leaving the hole areas reserved, and then scans the hole areas, avoiding continuous scanning of a sliced layer, resulting in heat accumulation, thereby reducing the risk of part deformation and cracking and effectively alleviating the problem of stress concentration.

[0055] As an optional method, after filling the paths of the hole areas and the linear areas to obtain the scanning paths corresponding to the marked sliced layers of the part, it further includes:

[0056] Fill the paths of the sliced layers of the part other than the marked sliced layers to obtain the scanning paths of the non-marked sliced layers of the part. The filling method of the scanning paths of the non-marked sliced layers is the same as that of the scanning paths of the linear areas. Since the non-marked sliced layers are not preset large-area sliced layers, there will be no situation of too much scanning time and heat accumulation causing thermal stress concentration, and then resulting in part deformation. Therefore, there is no need to perform zoning, and not zoning the non-marked sliced layers can also avoid the problem of too many overlapping positions caused by too many regions, and then avoid the problems of excessive local heat input and stress concentration.

[0057] As an optional method, after filling the paths of the hole areas and the linear areas to obtain the scanning paths corresponding to the marked sliced layers of the part, it further includes:

[0058] Judge whether the sliced layer is a marked sliced layer. If it is a marked sliced layer, scan the linear areas in the marked sliced layer based on the scanning paths of the linear areas until all the linear areas in the marked sliced layer are scanned; scan the hole areas in the marked sliced layer based on the scanning paths of the hole areas;

[0059] If the sliced layer is not a marked sliced layer, scan the sliced layer according to the scanning paths of the non-marked sliced layers;

[0060] Scan the next sliced layer until all the sliced layers are scanned to obtain the part.

[0061] When scanning the next slice layer, the scanning direction of the laser of the upper slice layer can be rotated by 60° and then the current slice layer can be scanned.

[0062] As an alternative, scanning the small hole area in the marked slice layer based on the small hole area scanning path includes:

[0063] Scanning the first small hole area based on the small hole area scanning path until the scanning of the first small hole area is completed; when scanning the small hole area, only scan the filling path of the small hole area and do not scan the contour line of the small hole area;

[0064] Perform the scanning of the second small hole area until the scanning of all small hole areas is completed, and the second small hole area and the first small hole area are adjacent small hole areas.

[0065] As an alternative, each slice layer of the part includes at least two slice layers of the part; when multiple parts are printed simultaneously, each part is separately identified in each printing layer, and it is allowed that there is a large-area slice layer in the first part of the same layer while there is no large-area slice layer in the second part. At this time, only the slice layer of the first part is divided into a linear area and a small hole area. Specifically, for the marked slice layer includes:

[0066] Determine the target slice layer in each slice layer based on the diameter of the small hole area; the target slice layer is the slice layer whose area, maximum length, and maximum width all meet the conditions;

[0067] Mark the target slice layer to obtain the marked slice layer.

[0068] Next, in combination with Figures 2 - 4 The scanning path generation method for laser additive manufacturing will be further elaborated.

[0069] See Figure 2 , taking a cuboid part with dimensions of 200×200×300mm 3 and having a rectangular through hole of 20×20×300mm 3 inside as an example for illustration. As shown in Figure 2 , the part slice layer includes two outer contour lines 1 and an internal entity 2. Before slicing, the shape of the small hole area is set to a circle in the slicing program, the diameter of the small hole area is 20mm, the distance between the small hole area and the contour line is greater than or equal to 40mm, and the distance between the center points of adjacent small hole areas is greater than or equal to 60mm. The recognition condition for a large-area entity is that the maximum distances in the X and Y directions of the printing surface are both greater than or equal to 160mm, and the area of the slice layer is greater than or equal to 6400Πmm 2 . After judgment, each slice layer of the part meets the recognition condition of the large-area entity, so each slice layer is recognized as a marked slice layer.

[0070] Refer to Figure 3 , according to the set conditions such as the diameter of the small hole area and the distance between the center points of adjacent small hole areas, the marked slice layer is divided into a linear area 3 and a small hole area 4.

[0071] Refer to Figure 4 , the marked slice layer is filled with paths in a parallel line filling manner, and the filled paths are segmented by the contour lines of the small hole area to obtain the filled paths as shown in Figure 4 . When printing, first scan the scanning paths in the linear area. After all the scanning is completed, scan each small hole area in turn. Exemplarily, as shown in Figure 4 , the laser first scans from point A to point B, then scans from point C to point D, and scans the next scanning path in the linear area. After all the scanning paths in the linear area are scanned, assuming that B is the starting point for scanning the small hole area, the laser moves to point B and scans from point B to point C, and then scans the next scanning path of this small hole area. After all are completed, scan the next small hole area until all the small hole areas are scanned, complete the scanning of this marked slice layer, and perform the scanning of the next slice layer to complete the printing of the part.

[0072] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer programs or instructions. When the computer program or instructions are loaded and executed on a computer, the processes or functions described in the embodiments of the present invention are executed in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, a terminal, a user device, or other programmable devices. The computer program or instructions can be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer program or instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center in a wired or wireless manner. The computer-readable storage medium can be any available medium that the computer can access, or a data storage device such as a server or data center that integrates one or more available media. The available medium can be a magnetic medium, such as a floppy disk, a hard disk, or a magnetic tape; it can also be an optical medium, such as a digital video disc (DVD); it can also be a semiconductor medium, such as a solid state drive (SSD).

[0073] Although the present invention has been described in connection with the various embodiments, however, in the process of implementing the claimed invention, those skilled in the art can understand and realize other variations of the disclosed embodiments by viewing the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other components or steps, and "a" or "one" does not exclude a plurality. A single processor or other unit may implement several functions recited in the claims. Certain measures are recited in mutually different dependent claims, but this does not mean that these measures cannot be combined to produce good results.

[0074] Although the present invention has been described in connection with specific features and their embodiments, it is obvious that various modifications and combinations can be made without departing from the spirit and scope of the present invention. Accordingly, the present specification and the drawings are merely exemplary illustrations of the present invention defined by the appended claims, and are considered to cover any and all modifications, variations, combinations, or equivalents within the scope of the present invention. Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these changes and modifications.

Claims

1. A scanning path generation method for laser additive manufacturing, characterized in that: include: Obtain the physical parameters of each slice layer of the part and the diameter of the small hole area; Physical parameters include the area, maximum length, and maximum width of the slice layer; Based on the diameter of the pinhole area, the slice layer whose area, the maximum length and the maximum width all meet the conditions is marked to obtain a marked slice layer; The marked slice layer is partitioned according to the edge contour line of the marked slice layer and the diameter of the small hole area, so as to obtain small hole areas and linear areas excluding the small hole areas that are evenly distributed in the marked slice layer; the distance between the center point of the small hole area and the edge contour line is greater than or equal to twice the diameter of the small hole area, and the distance between the center points of adjacent small hole areas is within the range of three times to five times the diameter of the small hole area; the maximum length of the marked slice layer is greater than or equal to eight times the diameter of the small hole area, the maximum width of the marked slice layer is greater than or equal to eight times the diameter of the small hole area, and the area of ​​the marked slice layer is greater than or equal to the product of 16π and the square of the diameter of the small hole area; Filling the marked slice layer to obtain multiple filling paths; The plurality of filling paths are segmented using the contour line of the pinhole area to obtain a scanning path corresponding to the marked slice layer of the part; the scanning path corresponding to the marked slice layer includes a pinhole area scanning path and a linear area scanning path; Performing path filling on the slice layers other than the marked slice layer in the part to obtain a scanning path of the unmarked slice layer of the part, wherein the filling method of the scanning path of the unmarked slice layer is the same as the filling method of the linear area scanning path; Determine whether the slice layer is a marked slice layer, and if it is a marked slice layer, scan the linear area in the marked slice layer based on the linear area scanning path until all the linear areas in the marked slice layer are scanned; scan the small hole area in the marked slice layer based on the small hole area scanning path; If the slice layer is not a marked slice layer, scanning the slice layer according to the scanning path of the non-marked slice layer; The next slice layer is scanned until all slice layers are scanned to obtain a part; the small hole area is scanned after the linear area is scanned.

2. The scanning path generation method for laser additive manufacturing according to claim 1, characterized in that: The scanning of the pinhole area in the marked slice layer based on the pinhole area scanning path comprises: Scanning the first pinhole area based on the pinhole area scanning path until the first pinhole area scanning is completed; when scanning the pinhole area, only scanning the filling path of the pinhole area; The scanning of the second pinhole area is performed until the scanning of all pinhole areas is completed, and the second pinhole area and the first pinhole area are adjacent pinhole areas.

3. The scanning path generation method for laser additive manufacturing according to claim 1, characterized in that: The linear area scanning path is a parallel line or a serpentine line; and scanning the next slice layer includes: The scanning direction of the previous slice layer is rotated by 60° before scanning the slice layer.

4. The scanning path generation method for laser additive manufacturing according to claim 1, characterized in that: Each slice layer of a part includes at least two slice layers of the part; the marked slice layer includes: Determine a target slice layer in each slice layer based on the diameter of the pinhole area; the target slice layer is a slice layer whose area, maximum length and maximum width all meet the conditions; The target slice layer is marked to obtain a marked slice layer.

5. The scanning path generation method for laser additive manufacturing according to claim 1, characterized in that: The shape of the small hole area is circular, elliptical, rectangular or triangular.

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