A scanning path planning method for additive manufacturing

Abstract

This application relates to a scanning path planning method for additive manufacturing. The method includes: generating parallel melting lines with a preset scanning spacing within a closed contour region for scanning and filling; when the part to be printed is a part that does not require splicing printing, dividing the region within the closed contour into a first region, a second region, and a third region; scanning the first region according to a first scanning and filling path, the second region according to a second scanning and filling path, and the third region according to a third scanning and filling path. This application achieves complete melting of the powder near the sidewalls of the upper surface of the three-dimensional part by using partitioned scanning and increasing the melting energy near the sidewalls of the upper surface, resulting in a smooth surface without holes or defects. This improves the forming quality of the upper surface near the sidewalls of the three-dimensional part and solves the problems of protrusions and holes near the sidewalls of the upper surface.

Description

Technical Field

[0001] This application relates to the field of additive manufacturing technology, and in particular to a scanning path planning method for additive manufacturing. Background Technology

[0002] In the powder bed additive manufacturing process, a powder layer of a certain thickness is laid on a substrate preheated to a certain temperature. A high-energy beam selectively melts the powder on the substrate in a back-and-forth manner according to the two-dimensional contour information of the current layer, processing one layer thickness. Then the substrate is lowered by one layer thickness, and a layer of metal powder of one layer thickness is laid on the processed layer. The two-dimensional cross-sectional information of the next layer is then introduced. This process is repeated layer by layer to complete the melting and forming of the entire three-dimensional part.

[0003] Since the powder bed forming process of metal materials is a process of successively stacking molten pools into layers and then building up the solid, the surface of the two-dimensional cross-section near the sidewall, formed by multiple layers, is a crucial component of the formed part, and its forming quality and accuracy are paramount. Furthermore, to meet the processing requirements of large-sized parts, splicing printing is often employed. This means that the current two-dimensional cross-section is not melted and processed in one go, but rather divided into multiple sub-sections, which are melted and spliced ​​together one by one. The splicing points involve the surface of each sub-section near its corresponding sidewall. The surfaces of the sub-sections near the sidewall are ultimately spliced ​​together to form the interior of the large-sized part; therefore, the surface quality of the sub-sections near their sidewalls is also particularly important.

[0004] In related technologies, powder bed additive manufacturing processes occur in a powder environment. Each molten pool contains varying amounts of powder particles, especially near the sidewalls of the powder bed in 3D parts. Near the sidewalls, the molten pools contain a large amount of loose powder. Due to surface tension, more powder is adsorbed near the molten pools, causing agglomeration and resulting in a "protrusion" on the upper surface of the 3D part near the sidewalls. Furthermore, when melting with the same energy scan line, the heating state of the upper surface near the sidewalls of the 3D part differs from that inside the part. The sidewalls are surrounded by a relatively cool, loose powder bed, resulting in faster heat dissipation. With the same linear energy density, the powder near the sidewalls of the upper surface is insufficient to completely melt. The under-melted powder particles are only connected by sintering necks, creating gaps and causing protrusions. When processing the next layer, the same energy input cannot penetrate the preset powder thickness to achieve complete melting. This accumulation layer by layer further deteriorates the sidewall formation, causing protrusions on the upper surface of the 3D part near the sidewalls. Metallographic examination of the Z-axis longitudinal section of the printed part revealed a hole defect of a certain thickness near the sidewall.

[0005] In addition, splicing printing is usually used when printing large-size 3D parts. However, due to poor melting of the splicing area during splicing printing, the splicing area may have a protrusion problem.

[0006] Therefore, it is necessary to provide a new technical solution to improve one or more of the problems existing in the above solutions.

[0007] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of this application, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0008] The purpose of this application is to provide a scanning path planning method for additive manufacturing, thereby overcoming, at least to some extent, one or more problems caused by the limitations and defects of related technologies.

[0009] A scanning path planning method for additive manufacturing according to an embodiment of this application includes:

[0010] The three-dimensional model of the part to be printed is divided into layers according to a preset layer thickness to obtain the two-dimensional cross-sectional information after layering. The two-dimensional cross-sectional information includes the closed contour and the region within the closed contour.

[0011] A parallel melt line scan fill path with a preset scan spacing is generated within the region of the closed contour; wherein, the parallel melt line scan fill path includes a first scan fill path, a second scan fill path, and a third scan fill path; the first scan fill path includes a scan fill path extending inward from the end of the parallel melt line by a first preset distance, the second scan fill path includes a scan fill path extending inward from the closed contour parallel to the direction of the parallel melt line by a second preset distance, and the third scan fill path is the scan fill path within the region of the closed contour excluding the first scan fill path and the second scan fill path;

[0012] When the part to be printed is a part that does not require splicing printing, the region within the closed contour is divided into a first region, a second region, and a third region, including: dividing the region formed from the side of the closed contour perpendicular to the direction of the parallel melting line to a first preset distance into the first region; dividing the region formed from the side of the closed contour parallel to the direction of the parallel melting line to a second preset distance into the second region; and dividing the region within the closed contour excluding the first region and the second region into the third region.

[0013] The first region is scanned according to the first scan fill path, the second region is scanned according to the second scan fill path, and the third region is scanned according to the third scan fill path; wherein, the energy of the second scan fill path is higher than the energy of the first scan fill path, and the energy of the first scan fill path is higher than the energy of the third scan fill path.

[0014] In the embodiments of this application, the first preset distance is less than the second preset distance.

[0015] In the embodiments of this application, the first preset distance is greater than 0 and less than one-third of the parallel melting line scan length.

[0016] In the embodiments of this application, the energy of the first scan fill path, the energy of the second scan fill path, and the energy of the third scan fill path are all calculated using the following formula:

[0017] (1)

[0018] In the formula, when calculating the energy of the first scan fill path, E represents the energy of the first scan fill path. E represents the preset layer thickness used to calculate the energy of the first scan fill path, h represents the preset scan spacing used to calculate the energy of the first scan fill path, P represents the scan power used to calculate the energy of the first scan fill path, V represents the scan movement speed used to calculate the energy of the first scan fill path, and R represents the scan resolution used to calculate the energy of the first scan fill path. When calculating the energy of the second scan fill path, E represents the energy of the second scan fill path. E represents the preset layer thickness used to calculate the energy of the second scan fill path, h represents the preset scan spacing used to calculate the energy of the second scan fill path, P represents the scan power used to calculate the energy of the second scan fill path, V represents the scan movement speed used to calculate the energy of the second scan fill path, and R represents the scan resolution used to calculate the energy of the second scan fill path. When calculating the energy of the third scan fill path, E represents the energy of the third scan fill path. The preset layer thickness is used to calculate the energy of the third scan fill path, h is used to calculate the preset scan spacing, P is used to calculate the scan power, V is used to calculate the scan movement speed, and R is used to calculate the scan resolution.

[0019] In embodiments of this application, the method further includes:

[0020] When the part to be printed is a part that needs to be spliced ​​together, the area within the closed outline is divided into at least a first printing area and a second printing area; wherein, there is an overlapping area between the first printing area and the second printing area;

[0021] Dividing the first printing area into a first area, a second area, and a third area includes: dividing the area formed from the side of the first printing area perpendicular to the direction of the parallel melting line to the first preset distance into the first area; dividing the area formed from the side of the first printing area parallel to the direction of the parallel melting line to the second preset distance into the second area; and dividing the area of ​​the first printing area other than the first area and the second area into the third area.

[0022] The area in the second printing area excluding the overlapping area is divided into a first area, a second area, and a third area, including: dividing the area formed by the side perpendicular to the direction of the parallel melt line to the first preset distance in the area in the second printing area excluding the overlapping area into the first area; dividing the area formed by the side parallel to the direction of the parallel melt line to the second preset distance in the area in the second printing area excluding the overlapping area into the second area; and dividing the area in the second printing area excluding the first area and the second area into the third area.

[0023] The first region is scanned according to the first scan fill path, the overlapping region is scanned according to the third scan fill path, the second region is scanned according to the second scan fill path, and the third region is scanned according to the third scan fill path; wherein, the energy of the second scan fill path is higher than the energy of the first scan fill path, and the energy of the first scan fill path is higher than the energy of the third scan fill path.

[0024] In embodiments of this application, the method further includes:

[0025] The first printing area is adjacent to the second printing area, and the direction of the parallel melting line of the first printing area is parallel to the direction of the parallel melting line of the second printing area;

[0026] Alternatively, the first printing area is adjacent to the second printing area, and the direction of the parallel melting line of the first printing area is not parallel to the direction of the parallel melting line of the second printing area.

[0027] In embodiments of this application, the width of the overlapping area is greater than the first preset distance.

[0028] The technical solutions provided by the embodiments of this application may include the following beneficial effects:

[0029] In one embodiment of this application, the method described above divides the region within the closed contour into a first region, a second region, and a third region. The first region is scanned according to a first scan fill path, the second region according to a second scan fill path, and the third region according to a third scan fill path, thus achieving partitioned scanning of the region within the closed contour. Simultaneously, the energy of the second scan fill path is higher than that of the first scan fill path, and the energy of the first scan fill path is higher than that of the third scan fill path. By partitioned scanning and increasing the melting energy near the sidewalls of the upper surface of the part to be printed, the powder near the sidewalls of the three-dimensional part is completely melted, resulting in a smooth surface without holes or defects. This improves the forming quality of the upper surface near the sidewalls of the three-dimensional part and solves the problems of protrusions and holes near the sidewalls of the upper surface of the three-dimensional part.

[0030] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0031] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. It is obvious that the drawings described below are merely some embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0032] Figure 1 The illustration schematically shows a three-dimensional part drawing scanned and printed using the conventional scanning method of Example 1;

[0033] Figure 2 The metallographic image of a three-dimensional part scanned and printed using the conventional scanning method of Example 1 is shown schematically.

[0034] Figure 3 This schematically illustrates a flowchart of the steps of a scanning path planning method for additive manufacturing in an exemplary embodiment of this application;

[0035] Figure 4 This schematic diagram illustrates the scanning path planning when no splicing printing is required in an exemplary embodiment of this application.

[0036] Figure 5 This schematically illustrates a flowchart of the steps of another additive manufacturing scanning path planning method in an exemplary embodiment of this application;

[0037] Figure 6 This schematic diagram illustrates a scanning path planning method for splicing printing in an exemplary embodiment of this application.

[0038] Figure 7 This schematic diagram illustrates another scanning path planning method for splicing printing in an exemplary embodiment of this application;

[0039] Figure 8 This schematically illustrates a three-dimensional part drawing scanned and printed using the scanning method of this application according to Embodiment 2;

[0040] Figure 9 A metallographic image of a three-dimensional part scanned and printed using the scanning method of this application according to Embodiment 2 is shown schematically.

[0041] Figure 10 The illustration schematically shows a three-dimensional part drawing scanned and printed using the conventional scanning method of Example 3;

[0042] Figure 11 The illustration schematically shows a three-dimensional part drawing scanned and printed using the scanning method of this application according to Embodiment 4. Detailed Implementation

[0043] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, they are provided to make this application more comprehensive and complete, and to fully convey the concept of the exemplary embodiments to those skilled in the art. The described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0044] Furthermore, the accompanying drawings are merely illustrative of this application and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and therefore repeated descriptions of them will be omitted. Some block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities. These functional entities can be implemented in software, in one or more hardware modules or integrated circuits, or in different network and / or processor devices and / or microcontroller devices.

[0045] This example implementation first provides a scanning path planning method for additive manufacturing. (See reference...) Figure 3 As shown, the method may include steps S101 to S104.

[0046] In step S101, the three-dimensional model of the part to be printed is layered according to a preset layer thickness to obtain the two-dimensional cross-sectional information after layering. The two-dimensional cross-sectional information includes the closed contour and the region within the closed contour.

[0047] Step S102: Generate a parallel melt line scan fill path with a preset scan spacing in the region within the closed contour; wherein, the parallel melt line scan fill path includes a first scan fill path, a second scan fill path, and a third scan fill path; the first scan fill path includes a scan fill path extending inward from the end of the parallel melt line by a first preset distance, the second scan fill path includes a scan fill path extending inward from the closed contour parallel to the direction of the parallel melt line by a second preset distance, and the third scan fill path is the scan fill path within the region within the closed contour excluding the first scan fill path and the second scan fill path.

[0048] Step S103: When the part to be printed is a part that does not require splicing printing, the area within the closed contour is divided into a first area, a second area and a third area, including: dividing the area formed from the side of the closed contour perpendicular to the direction of the parallel melting line to a first preset distance into the first area; dividing the area formed from the side of the closed contour parallel to the direction of the parallel melting line to a second preset distance into the second area; and dividing the area within the closed contour excluding the first and second areas into the third area.

[0049] Step S104: Scan the first region according to the first scan filling path, scan the second region according to the second scan filling path, and scan the third region according to the third scan filling path; wherein, the energy of the second scan filling path is higher than the energy of the first scan filling path, and the energy of the first scan filling path is higher than the energy of the third scan filling path.

[0050] In one embodiment of this application, the method described above divides the region within a closed contour into a first region, a second region, and a third region. The first region is scanned according to a first scan fill path, the second region according to a second scan fill path, and the third region according to a third scan fill path, thus achieving partitioned scanning of the region within the closed contour. Simultaneously, the energy of the second scan fill path is higher than that of the first scan fill path, and the energy of the first scan fill path is higher than that of the third scan fill path. By partitioned scanning and increasing the melting energy near the sidewalls of the upper surface of the part to be printed, the powder near the sidewalls of the three-dimensional part is completely melted, resulting in a smooth surface without holes or defects. This improves the forming quality of the upper surface near the sidewalls of the three-dimensional part and solves the problems of protrusions and holes near the sidewalls of the upper surface of the three-dimensional part.

[0051] Below, we will refer to Figure 4 The steps of the method described above in this example embodiment will be explained in more detail.

[0052] In step S101, the three-dimensional model of the part to be printed obtains two-dimensional cross-sectional information according to the preset layer thickness of the part to be printed. The two-dimensional cross-sectional information includes the closed contour and the region within the closed contour.

[0053] In step S102, a parallel melt line scan fill path with a preset scan spacing of h is generated within the closed contour region. The parallel melt line scan fill path includes a first scan fill path, a second scan fill path, and a third scan fill path. The preset scan spacing of the first scan fill path, the second scan fill path, and the third scan fill path are all h. The value of the preset scan spacing can be set according to actual conditions, which will not be elaborated in this application.

[0054] The first scanning fill path includes a scanning fill path extending inwards from the end of the parallel melt line by a first preset distance. The parallel melt line has two ends; taking the left and right ends as examples, the first scanning fill path includes a scanning fill path extending inwards (i.e., to the right) from the left end of the parallel melt line by a first preset distance, and a scanning fill path extending inwards (i.e., to the left) from the right end of the parallel melt line by a first preset distance. The first preset distance is denoted by 'a'. The range of the first preset distance is 0.2mm-1mm, and the first preset distance can be 0.2mm, 0.5mm, 0.7mm, 0.8mm, 1mm, etc., and can be set according to actual conditions; this application will not elaborate on this.

[0055] Similarly, the second scanning fill path includes a scanning fill path extending inwards from the closed contour parallel to the direction of the melting line by a second preset distance. The closed contour parallel to the direction of the melting line has two sides; taking the upper and lower sides as examples, the second scanning fill path includes a scanning fill path extending inwards (i.e., downwards) from the upper side parallel to the direction of the melting line by a second preset distance, and a scanning fill path extending inwards (i.e., upwards) from the lower side parallel to the direction of the melting line by a second preset distance. The second preset distance is denoted by b. The range of the second preset distance is 0.3mm-1.5mm, and the second preset distance can be 0.3mm, 0.5mm, 0.7mm, 0.8mm, 1.0mm, 1.3mm, 1.5mm, etc., and can be set according to actual conditions; this application will not elaborate on this.

[0056] The third scan fill path is the scan fill path within the closed contour region excluding the first and second scan fill paths. The first, second, and third scan fill paths together constitute the parallel melt line scan fill path within the closed contour region.

[0057] In steps S103 and S104, when the parts to be printed do not require splicing, the area formed from the side perpendicular to the direction of the parallel melting line in the closed contour to the first preset distance is designated as the first region. There are two sides perpendicular to the direction of the parallel melting line in the closed contour. Therefore, there are also two first regions formed.

[0058] Similarly, the area formed by the side parallel to the direction of the melt line within the closed contour and the second preset distance is designated as the second region. There are two sides parallel to the direction of the melt line within the closed contour. Therefore, there are also two second regions. The third region is the area within the closed contour that does not include the first and second regions. The first, second, and third regions together constitute the area within the closed contour. For example... Figure 4 As shown, the first zone is represented by A, the second zone by B, and the third zone by C.

[0059] By dividing the parallel melt line scanning fill path within a closed contour into a first scan fill path, a second scan fill path, and a third scan fill path, the closed contour area is further divided into three zones. The first zone is scanned according to the first scan fill path, the second zone according to the second scan fill path, and the third zone according to the third scan fill path, thus achieving zoned scanning within the closed contour. Furthermore, the energy of the second scan fill path is higher than that of the first scan fill path, and the energy of the first scan fill path is higher than that of the third scan fill path. By increasing the melting energy near the sidewalls of the upper surface of the part to be printed, the powder near the sidewalls of the 3D part is completely melted, resulting in a smooth surface without holes or defects. This improves the forming quality of the upper surface near the sidewalls of the 3D part and solves the problems of protrusions and holes near the sidewalls of the upper surface of the 3D part.

[0060] The third region is the internal area, and the energy of its corresponding scanning filling path is just enough to completely melt the powder. The first and second regions are edge regions, affected by heat dissipation, requiring higher melting energy to compensate for heat loss. Therefore, the energy of the first and second scanning filling paths is higher than that of the third scanning filling path. The parallel melting lines in the melting filling process are generally scanned back along their ends. Due to the acceleration and deceleration factors of the parallel melting lines, the high-energy beam stays for a longer time than in the middle section of the parallel melting lines. Therefore, the heat input (i.e., energy) at the ends of the parallel melting lines is relatively higher, and the energy compensation can be relatively less. Therefore, the energy of the first scanning filling path is less than that of the second scanning filling path.

[0061] In one embodiment, the first preset distance is less than the second preset distance.

[0062] Understandably, the first preset distance is less than the second preset distance, i.e., a < b. On one hand, the end of the parallel melting line is the starting or ending point of the high-energy beam scan. Due to the acceleration and deceleration factors of the scan line (i.e., the parallel melting line), the high-energy beam stays at the end of the parallel melting line for a longer time than in the middle section. Therefore, the heat input at the end of the parallel melting line is relatively higher. On the other hand, compared to the end of the parallel melting line, the contact area between the parallel melting line near the sidewall of the upper surface of the part to be printed and the loose powder bed is larger. Therefore, its heat loss is relatively smaller than that in the second region where the second filling scan path is located. The first preset distance being less than the second preset distance results in dense, pore-free melting of the sidewall edges and a smooth upper surface of the printed 3D part.

[0063] Furthermore, the first preset distance is greater than 0 and less than one-third of the parallel melting line scan length.

[0064] Specifically, the first preset distance refers to the distance between the two ends of the parallel melt line. A parallel melt line is divided into three parts: the left end, the right end, and the middle section. Therefore, the first preset distance must be at least one-third of the total scanning length of the parallel melt line. To ensure the forming quality of the 3D part, the first preset distance must exist, and therefore, the first preset distance is greater than 0.

[0065] In one embodiment, the energy of the first scan fill path, the energy of the second scan fill path, and the energy of the third scan fill path are all calculated using the following formula:

[0066] (1)

[0067] In the formula, when calculating the energy of the first scan fill path, E represents the energy of the first scan fill path. E represents the preset layer thickness used to calculate the energy of the first scan fill path, h represents the preset scan spacing used to calculate the energy of the first scan fill path, P represents the scan power used to calculate the energy of the first scan fill path, V represents the scan movement speed used to calculate the energy of the first scan fill path, and R represents the scan resolution used to calculate the energy of the first scan fill path. When calculating the energy of the second scan fill path, E represents the energy of the second scan fill path. E represents the preset layer thickness used to calculate the energy of the second scan fill path, h represents the preset scan spacing used to calculate the energy of the second scan fill path, P represents the scan power used to calculate the energy of the second scan fill path, V represents the scan movement speed used to calculate the energy of the second scan fill path, and R represents the scan resolution used to calculate the energy of the second scan fill path. When calculating the energy of the third scan fill path, E represents the energy of the third scan fill path. The preset layer thickness is used to calculate the energy of the third scan fill path, h is used to calculate the preset scan spacing, P is used to calculate the scan power, V is used to calculate the scan movement speed, and R is used to calculate the scan resolution.

[0068] It is understandable that the energy of the first scan fill path, the energy of the second scan fill path, and the energy of the third scan fill path can all be calculated using the above formula. The fact that the energy of the second scan fill path is higher than that of the first scan fill path, and the energy of the first scan fill path is higher than that of the third scan fill path, can be achieved by controlling the scan resolution of each scan fill path.

[0069] Furthermore, increasing the scanning resolution of the high-energy beam, i.e., reducing the preset scanning interval of the high-energy beam, results in higher energy for the scanning filling path. Generally, the energy of each scanning filling path is controlled by adjusting the corresponding scanning power and scanning speed. However, due to the limitations of the device's hardware response speed, adjusting the scanning power and scanning speed can cause a certain degree of positioning accuracy deviation in the high-energy beam, affecting the forming effect of the printed part. Therefore, controlling the energy of each scanning filling path by increasing the scanning resolution is simple and easy to implement. The three-dimensional part printed using the scanning method provided in this application has a smooth upper surface near the sidewall, and the internal structure of the sidewall is dense and free of pores or defects upon inspection.

[0070] In one embodiment, reference Figure 5 , Figure 6 and Figure 7 The method further includes steps S201 to S204.

[0071] In step S201: when the printable part is a printable part that needs to be spliced, the area within the closed outline is divided into at least a first printable area and a second printable area; wherein, there is an overlapping area between the first printable area and the second printable area.

[0072] Step S202: Divide the first printing area into a first area, a second area, and a third area, including: dividing the area formed by the side perpendicular to the direction of the parallel melting line in the first printing area to a first preset distance into the first area; dividing the area formed by the side parallel to the direction of the parallel melting line in the first printing area to a second preset distance into the second area; and dividing the area in the first printing area other than the first and second areas into the third area.

[0073] Step S203: Divide the area in the second printing area after removing the overlapping area into a first area, a second area, and a third area, including: dividing the area formed by the side perpendicular to the direction of the parallel melt line to a first preset distance in the area in the second printing area after removing the overlapping area into a first area; dividing the area formed by the side parallel to the direction of the parallel melt line to a second preset distance in the area in the second printing area after removing the overlapping area into a second area; and dividing the area in the second printing area after removing the overlapping area, excluding the first and second areas, into a third area.

[0074] Step S204: The first region is scanned according to the first scan filling path, the overlapping region is scanned according to the third scan filling path, the second region is scanned according to the second scan filling path, and the third region is scanned according to the third scan filling path; wherein, the energy of the second scan filling path is higher than the energy of the first scan filling path, and the energy of the first scan filling path is higher than the energy of the third scan filling path.

[0075] In step S201, large-sized printable parts generally require splicing before printing can be completed. When splicing is required, the closed contour area of ​​the two-dimensional cross-section of the printable part is divided into at least a first printing area and a second printing area. There is an overlapping area between the first and second printing areas, and this overlapping area has a certain width, which is greater than a first preset distance. For example... Figure 6 and Figure 7 As shown, the width of the overlapping area is represented by w.

[0076] In steps S202 and S203, the area formed by the side perpendicular to the direction of the parallel melt line in the first printing area to a first preset distance is designated as the first area. There are two sides perpendicular to the direction of the parallel melt line in the first printing area. Therefore, two first areas are formed. Similarly, the area formed by the side parallel to the direction of the parallel melt line in the first printing area to a second preset distance is designated as the second area. There are two sides parallel to the direction of the parallel melt line in the first printing area. Therefore, two second areas are also formed. The third area is the region within the first printing area that does not include the first and second areas. Dividing the first printing area into zones facilitates subsequent partitioned scanning.

[0077] The area within the second printing area, excluding the overlapping areas, formed by the side perpendicular to the direction parallel to the melt line and extending to a first preset distance, is designated as the first area. There are two sides perpendicular to the direction parallel to the melt line within the second printing area, excluding the overlapping areas. Therefore, there are two first areas. Similarly, the area within the second printing area, excluding the overlapping areas, formed by the side parallel to the direction parallel to the melt line and extending to a second preset distance, is designated as the second area. There are two sides parallel to the direction parallel to the melt line within the second printing area, excluding the overlapping areas. Therefore, there are also two second areas. The third area is the area within the second printing area that does not include the first and second areas. Dividing the area within the second printing area (excluding the overlapping areas) facilitates subsequent partitioned scanning.

[0078] The overlapping area is the region where the parts to be printed meet during the splicing process. This application divides the areas of the first and second printing areas, excluding the overlapping area, into zones and performs zone scanning to eliminate the problem of raised areas at the splicing points when large-sized parts are printed together.

[0079] In step S204, the areas within the first and second printing areas, excluding the overlapping areas, are divided into a first area, a second area, and a third area, respectively. The first area is scanned according to the first scan fill path, the second area according to the second scan fill path, the third area according to the third scan fill path, and the overlapping area according to the third scan fill path. This achieves partitioned scanning of the area within the closed contour. Simultaneously, the energy of the second scan fill path is higher than that of the first scan fill path, and the energy of the first scan fill path is higher than that of the third scan fill path. Energy differentiation is not performed in the overlapping area, ensuring that the parts to be printed (which require splicing) can be fully melted in the overlapping area. This avoids bulging at the splicing points and improves the forming quality of the 3D parts to be printed.

[0080] It should be noted that when melting the first printing area, the energy of the first scan fill path and the energy of the second scan fill path were planned for the overlapping area between the first and second printing areas. When melting the second printing area, the energy of the first scan fill path and the energy of the second scan fill path are not planned again for the overlapping area between the first and second printing areas; instead, the energy of the third scan fill path is used for melting in the overlapping area.

[0081] In spliced ​​printing, bulges may appear on the upper surface of the part near the sidewalls. Therefore, during the printing process of parts requiring spliced ​​printing, a scanning strategy is employed: the first area is scanned according to the first scan fill path, the second area according to the second scan fill path, the third area according to the third scan fill path, and the overlapping area is scanned according to the third scan fill path. Simultaneously, an energy strategy is used where the energy of the second scan fill path is higher than that of the first scan fill path, and the energy of the first scan fill path is higher than that of the third scan fill path. Therefore, bulges and holes near the sidewalls of the upper surface of the 3D part requiring spliced ​​printing can be avoided.

[0082] It should be noted that when the area within the closed contour of the two-dimensional cross-section of the workpiece to be printed is divided into at least a first printing area and a second printing area, the area within the closed contour of the two-dimensional cross-section of the workpiece to be printed can be divided into three or four printing areas. The specific division depends on the actual situation.

[0083] When divided into three printing areas, the area within the closed contour of the two-dimensional cross-section of the workpiece to be printed is divided into a first printing area, a second printing area, and a third printing area. The region division and subsequent scanning strategy for the first printing area when divided into three printing areas are the same as when divided into two printing areas. The difference is that the printing area located in the middle area (the second printing area) overlaps not only with the first printing area but also with the third printing area. When there are two overlapping areas on the left and right sides of the printing area located in the middle area, these two overlapping areas need to be removed when dividing the printing area in the middle area, and then scanning is performed after partitioning. The overlapping areas are scanned according to the third scan fill path.

[0084] In one embodiment, the method further includes:

[0085] The first printing area is adjacent to the second printing area, and the direction of the parallel melting line of the first printing area is parallel to the direction of the parallel melting line of the second printing area.

[0086] Alternatively, the first printing area is adjacent to the second printing area, and the direction of the parallel melting line of the first printing area is not parallel to the direction of the parallel melting line of the second printing area.

[0087] It is understandable that printing in the first and second printing areas includes two scenarios: Scenario 1 and Scenario 2. Scenario 1: As... Figure 6 As shown, the first printing area and the second printing area are adjacent, and the direction of the parallel melt line in the first printing area is parallel to the direction of the parallel melt line in the second printing area. Case 2: [Example 2] Figure 7As shown, the first and second printing areas are adjacent, and the parallel melting line direction of the first printing area is not parallel to the parallel melting line direction of the second printing area. Regardless of the situation, it is possible to print parts that need to be joined together, avoiding protrusions at the joints of the 3D parts and improving the final forming quality of the 3D parts.

[0088] In one embodiment, the width of the overlapping area is greater than a first preset distance.

[0089] It is understandable that the width of the overlapping area is greater than the first preset distance. The width of the overlapping area is 1mm-2mm, and can be 1mm, 1.3mm, 1.5mm, 1.7mm, 1.9mm, 2mm, etc. The specific width can be set according to the actual situation. When setting the width of the overlapping area, the condition that the width of the overlapping area is greater than the first preset distance must also be met.

[0090] The following embodiments further illustrate this application.

[0091] It should be noted that the powder used in Examples 1, 2, 3, and 4 is TC4 powder with a particle size range of 45μm-106μm. In the process of printing the part to be printed into a three-dimensional component, the conventional substrate preheating, powder spreading, and powder preheating processes are the same; the difference lies in the selective melting process, which mainly involves the scanning method. Therefore, this section primarily describes the conventional scanning method used in Example 1, the scanning method of this application used in Example 2, the conventional scanning method for splicing printing in Example 3, and the scanning method of this application for splicing printing in Example 4. Examples 3 and 4 specifically address scanning the area within a closed contour into a first printing area, a second printing area, and a third printing area.

[0092] Example 1 (scanning and printing using conventional scanning methods):

[0093] Step 1: Divide the 3D model of the part to be printed into layers with a preset layer thickness of 0.05mm to obtain the 2D cross-sectional information after layering; the 2D cross-sectional information includes the closed contour and the area within the closed contour.

[0094] Step 2: Within the closed contour, scan the filling path using parallel melting lines with a preset scanning interval, ranging from 0.05mm to 0.2mm. The scanning power is 900W, the scanning speed is 5m / s, the preset scanning interval is 0.1mm, the preset layer thickness is 0.05mm, the scanning resolution is 0.1mm, and the calculated energy is 6000J.

[0095] Example 2 (scanning and printing using the method of this application):

[0096] Step 1: Divide the 3D model of the part to be printed into layers with a preset layer thickness of 0.05mm to obtain the 2D cross-sectional information after layering; the 2D cross-sectional information includes the closed contour and the area within the closed contour.

[0097] Step 2: Generate parallel melt line scan fill paths with a preset scan spacing within the closed contour area. The preset scan spacing ranges from 0.05mm to 0.2mm. The parallel melt line scan fill paths include a first scan fill path, a second scan fill path, and a third scan fill path. The first scan fill path includes a scan fill path extending inward from the end of the parallel melt line by a first preset distance. The second scan fill path includes a scan fill path extending inward from the closed contour parallel to the direction of the parallel melt line by a second preset distance. The third scan fill path is the scan fill path within the closed contour excluding the first and second scan fill paths.

[0098] Step 3: When the part to be printed is a part that does not require splicing printing, the area within the closed contour is divided into a first area, a second area, and a third area, including: the area formed by the side of the closed contour perpendicular to the direction of the parallel melting line to a first preset distance is divided into a first area; the area formed by the side of the closed contour parallel to the direction of the parallel melting line to a second preset distance is divided into a second area; and the area within the closed contour excluding the first and second areas is divided into a third area.

[0099] Step 4: Scan the first area according to the first scan filling path, the second area according to the second scan filling path, and the third area according to the third scan filling path; wherein, the scanning power is 900W, the scanning movement speed is 5m / s, the preset scanning spacing is 0.1mm, the preset layer thickness is 0.05mm, the scanning resolution is 0.1mm, and the energy of the third scan filling path is calculated to be 6000J according to formula (1). The energy of the second scan filling path can be 1.2-1.3 times the energy of the third scan filling path. The energy of the first scan filling path can be 1.1-1.2 times the energy of the third scan filling path.

[0100] from Figure 1 , Figure 2 , Figure 8 and Figure 9 It can be seen that during the printing process of the workpiece into a three-dimensional part, the conventional scanning method of Example 1 produces protrusions and holes on the upper surface of the three-dimensional part near the sidewall. The scanning method of Example 2, used in this application, produces a smooth upper surface without protrusions or holes near the sidewall. This demonstrates that the scanning method of this application solves the problem of protrusions and holes on the upper surface of three-dimensional parts near the sidewall.

[0101] Example 3 (Conventional scanning method when splicing and printing are required):

[0102] Step 1: When the printable part is a piece that needs to be spliced ​​together, the area within the closed outline is divided into a first printing area, a second printing area, and a third printing area; there is an overlap between the first and second printing areas, and there is an overlap between the second and third printing areas. The second printing area is the printing area located in the middle area, therefore, the second printing area has two overlapping areas.

[0103] Step 2: In the first, second, and third printing areas, a parallel melting line scanning and filling path with a preset scanning interval is used for scanning. The preset scanning interval ranges from 0.05mm to 0.2mm. The scanning power is 900W, the scanning speed is 5m / s, the preset scanning interval is 0.1mm, the preset layer thickness is 0.05mm, and the scanning resolution is 0.1mm. According to formula (1), the energy of the parallel melting line scanning and filling path in the first printing area is calculated to be 6000J. The energy of the parallel melting line scanning and filling path in the second and third printing areas is equal to that in the first printing area.

[0104] Example 4 (Scanning method for this application when splicing and printing is required):

[0105] Step 1: When the printable part is a piece that needs to be spliced ​​together, the area within the closed outline is divided into a first printing area, a second printing area, and a third printing area; there is an overlap between the first and second printing areas, and there is an overlap between the second and third printing areas. The second printing area is the printing area located in the middle area, therefore, the second printing area has two overlapping areas.

[0106] Step 2: Divide the first printing area into a first area, a second area, and a third area, including: dividing the area formed by the side perpendicular to the direction of the parallel melting line in the first printing area to a first preset distance into the first area; dividing the area formed by the side parallel to the direction of the parallel melting line in the first printing area to a second preset distance into the second area; and dividing the area in the first printing area other than the first and second areas into the third area.

[0107] Step 3: Divide the area in the second printing area after removing the two overlapping areas into a first area, a second area, and a third area, including: dividing the area formed by the side perpendicular to the direction of the parallel melt line to a first preset distance from the area in the second printing area after removing the overlapping areas into a first area; dividing the area formed by the side parallel to the direction of the parallel melt line to a second preset distance from the area in the second printing area after removing the overlapping areas into a second area; and dividing the area in the second printing area after removing the overlapping areas, excluding the first and third areas, into a third area.

[0108] Step 4: The first region is scanned according to the first scan filling path, the overlapping region is scanned according to the third scan filling path, the second region is scanned according to the second scan filling path, and the third region is scanned according to the third scan filling path; wherein, the scanning power is 900W, the scanning movement speed is 5m / s, the preset scanning spacing is 0.1mm, the preset layer thickness is 0.05mm, the scanning resolution is 0.1mm, and the energy of the third scan filling path is calculated to be 6000J according to formula (1). The energy of the second scan filling path can be 1.2-1.3 times the energy of the third scan filling path. The energy of the first scan filling path can be 1.1-1.2 times the energy of the third scan filling path.

[0109] from Figures 10 to 11 It can be seen that during the printing process of the workpiece into a three-dimensional part, the three-dimensional part obtained using the conventional scanning method of Example 3 exhibits a protrusion at the joint. The three-dimensional part obtained using the scanning method of this application (Example 4) shows no protrusion at the joint. This indicates that the scanning method of this application solves the problem of protrusions at the joint of three-dimensional parts.

[0110] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein.

Claims

1. A scanning path planning method for additive manufacturing, characterized in that, The method includes: The three-dimensional model of the part to be printed is divided into layers according to a preset layer thickness to obtain the two-dimensional cross-sectional information after layering. The two-dimensional cross-sectional information includes the closed contour and the region within the closed contour. A parallel melt line scan fill path with a preset scan spacing is generated within the region of the closed contour; wherein, the parallel melt line scan fill path includes a first scan fill path, a second scan fill path, and a third scan fill path; the first scan fill path includes a scan fill path extending inward from the end of the parallel melt line by a first preset distance, the second scan fill path includes a scan fill path extending inward from the closed contour parallel to the direction of the parallel melt line by a second preset distance, and the third scan fill path is the scan fill path within the region of the closed contour excluding the first scan fill path and the second scan fill path; When the part to be printed is a part that does not require splicing printing, the region within the closed contour is divided into a first region, a second region, and a third region, including: dividing the region formed from the side of the closed contour perpendicular to the direction of the parallel melting line to a first preset distance into the first region; dividing the region formed from the side of the closed contour parallel to the direction of the parallel melting line to a second preset distance into the second region; and dividing the region within the closed contour excluding the first region and the second region into the third region. The first region is scanned according to the first scan fill path, the second region is scanned according to the second scan fill path, and the third region is scanned according to the third scan fill path; wherein, the energy of the second scan fill path is higher than the energy of the first scan fill path, and the energy of the first scan fill path is higher than the energy of the third scan fill path.

2. The scanning path planning method for additive manufacturing according to claim 1, characterized in that, The first preset distance is less than the second preset distance.

3. The scanning path planning method for additive manufacturing according to claim 2, characterized in that, The first preset distance is greater than 0 and less than one-third of the parallel melting line scan length.

4. The scanning path planning method for additive manufacturing according to claim 1, characterized in that, The energy of the first scan fill path, the energy of the second scan fill path, and the energy of the third scan fill path are all calculated using the following formula: （1） In the formula, when calculating the energy of the first scan fill path, E represents the energy of the first scan fill path. E represents the preset layer thickness used to calculate the energy of the first scan fill path, h represents the preset scan spacing used to calculate the energy of the first scan fill path, P represents the scan power used to calculate the energy of the first scan fill path, V represents the scan movement speed used to calculate the energy of the first scan fill path, and R represents the scan resolution used to calculate the energy of the first scan fill path. When calculating the energy of the second scan fill path, E represents the energy of the second scan fill path. E represents the preset layer thickness used to calculate the energy of the second scan fill path, h represents the preset scan spacing used to calculate the energy of the second scan fill path, P represents the scan power used to calculate the energy of the second scan fill path, V represents the scan movement speed used to calculate the energy of the second scan fill path, and R represents the scan resolution used to calculate the energy of the second scan fill path. When calculating the energy of the third scan fill path, E represents the energy of the third scan fill path. The preset layer thickness is used to calculate the energy of the third scan fill path, h is used to calculate the preset scan spacing, P is used to calculate the scan power, V is used to calculate the scan movement speed, and R is used to calculate the scan resolution.

5. The scanning path planning method for additive manufacturing according to any one of claims 1 to 4, characterized in that, The method further includes: When the part to be printed is a part that needs to be spliced ​​together, the area within the closed outline is divided into at least a first printing area and a second printing area; wherein, there is an overlapping area between the first printing area and the second printing area; Dividing the first printing area into a first area, a second area, and a third area includes: dividing the area formed from the side of the first printing area perpendicular to the direction of the parallel melting line to the first preset distance into the first area; dividing the area formed from the side of the first printing area parallel to the direction of the parallel melting line to the second preset distance into the second area; and dividing the area of ​​the first printing area other than the first area and the second area into the third area. The area in the second printing area excluding the overlapping area is divided into a first area, a second area, and a third area, including: dividing the area formed by the side perpendicular to the direction of the parallel melt line to the first preset distance in the area in the second printing area excluding the overlapping area into the first area; dividing the area formed by the side parallel to the direction of the parallel melt line to the second preset distance in the area in the second printing area excluding the overlapping area into the second area; and dividing the area in the second printing area excluding the first area and the second area into the third area. The first region is scanned according to the first scan fill path, the overlapping region is scanned according to the third scan fill path, the second region is scanned according to the second scan fill path, and the third region is scanned according to the third scan fill path; wherein, the energy of the second scan fill path is higher than the energy of the first scan fill path, and the energy of the first scan fill path is higher than the energy of the third scan fill path.

6. The scanning path planning method for additive manufacturing according to claim 5, characterized in that, The method further includes: The first printing area is adjacent to the second printing area, and the direction of the parallel melting line of the first printing area is parallel to the direction of the parallel melting line of the second printing area; Alternatively, the first printing area is adjacent to the second printing area, and the direction of the parallel melting line of the first printing area is not parallel to the direction of the parallel melting line of the second printing area.

7. The scanning path planning method for additive manufacturing according to claim 5, characterized in that, The width of the overlapping area is greater than the first preset distance.

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