Laser scanning method, device and storage medium for powder bed fusion process

Abstract

A laser scanning method, device, and storage medium for a powder bed fusion process, wherein the scanning method includes: slicing a part to be printed to obtain a cross-section to be scanned having one or more closed polygons; selecting part or all of at least one polygon as a region to be processed, and filling the interior of the region to be processed with fill lines; all fill lines close to or connected to the contour boundary of the polygon are parallel to each other; and scanning and sorting the parallel fill lines f(k) so that the endpoint of a later scanned fill line that is close to or connected to the contour cannot exceed the adjacent previously scanned fill line. By controlling the scanning order of the fill lines that are connected to or close to the contour, the present invention can accurately control the shape of the molten pool formed by the fill lines, so that the molten pool formed by the later scanned fill lines can adhere to one side of the molten pool formed by the previous scan to the greatest extent possible, which is beneficial to controlling the local temperature gradient of the molten pool and improving the surface quality and density of the part.

Description

Technical Field

[0001] The present application relates to the field of additive manufacturing technology, and in particular to a laser scanning method, apparatus, computer equipment, and storage medium for a powder bed fusion process. Background Art

[0002] Selective laser melting (SLM) is a rapid manufacturing technology that creates three-dimensional workpieces by controlling laser scanning layer by layer, stacking them one by one. The process flow is as follows: First, the 3D model of the workpiece is sliced ​​to obtain the contour information of each layer; powdered material is evenly spread on the work surface, and the laser selectively melts the powder according to system instructions; after completing one section, a new layer of material is applied, and scanning continues selectively based on the cross-sectional information corresponding to the 3D object; this method is then repeated for the next section, ultimately resulting in the 3D workpiece. The advantages of this method are that it can be used to manufacture metal workpieces with high process flexibility, excellent mechanical properties, and high dimensional accuracy.

[0003] However, during selective laser melting, heat distribution is concentrated in the area scanned by the laser, which can easily form a large temperature gradient with the surrounding powder not scanned by the laser, causing problems such as warping, deformation, and cracking. Considering that changes in the laser scanning method during the construction process, such as the scanning path, scanning power, scanning speed, and scanning spacing, will affect the distribution of heat and residual stress, and thus the final manufacturing effect, the design of laser scanning methods has always been a research topic in this technology.

[0004] In the existing technology, the commonly used scanning methods can be mainly divided into parallel line scanning, contour equidistant line scanning, and a mixture of the two. Common partitioning methods include strip type and checkerboard type, but most of them do not clearly stipulate the order of scanning lines; and the order of scanning lines will greatly affect the local melt pool morphology, thereby affecting the surface quality and density of the printed parts. Summary of the Invention

[0005] Based on this, it is necessary to provide a laser scanning method, device, computer equipment and storage medium for powder bed fusion process to address the above technical problems. This method can effectively improve the surface quality and density of the molded parts and suppress local warping (especially at the contour).

[0006] To achieve the above object, the present invention provides a laser scanning method for a powder bed fusion process, the method comprising the following steps:

[0007] Slicing the part to be printed to obtain a section to be scanned, where the section to be scanned is one or more closed polygons;

[0008] Select part or all of at least one polygon as the area to be processed, and scan the area to be processed using the following strategy:

[0009] The interior of the area to be processed is filled with fill lines; all fill lines f(k) (k=1, 2, ...m) that are close to or connected to the outline of the polygon are parallel to each other;

[0010] The parallel filling lines f(k) are scanned and sorted so that the endpoint of a later scanned filling line that is close to or connected to the contour cannot exceed the adjacent previously scanned filling line.

[0011] As a further preferred embodiment of the present invention, scanning and sorting the parallel filling lines f(k) specifically includes the following steps:

[0012] Step 31: Create a pair of unit vectors with opposite directions perpendicular to the parallel filling lines, defined as

[0013] Step 32: Take any point on each edge of the area to be processed and draw a unit vector through the point that is parallel to f(k) and points to the interior of the part to be printed. according to The direction of is parallel to the edge, and Obtain described is the unit vector of the edge;

[0014] Step 33: When one of the filling lines f(k) is close to or connected to two edges of the area to be processed, calculate the unit vectors of the two edges. and and The product of the product of the numbers, if Then the filling line is divided into two or more than two, and n new filling lines f′(k) (k=1, 2, ...n) (n≥m) that are close to or connected to the contour are obtained, and each filling line is close to or connected to only one edge of the area to be processed;

[0015] Step 34: For each fill line in the fill line f′(k), the unit vector of the only side of the polygon close to or connected to the fill line is Respectively Find the dot product if Then determine the sort vector of the filling line as Otherwise, the sort vector of the fill line is determined as

[0016] Step 35 : Group adjacent filling lines with the same sorting vector into a scanning group, and scan the filling lines in the same scanning group in sequence according to the direction of their sorting vectors.

[0017] As a further preferred embodiment of the present invention, when the profile includes two or more scan groups, the two or more scan groups are separated by or Scan in sequence in the following directions.

[0018] As a further preferred embodiment of the present invention, the filling line close to or connected to the contour boundary is a filling line whose endpoint is within 0.5 mm from the contour.

[0019] As a further preferred embodiment of the present invention, in step 33, the filling line is divided into two, and the dividing point is the midpoint of the filling line.

[0020] The present invention also provides a laser scanning device for a powder bed fusion process, the device comprising:

[0021] a slicing module for slicing the part to be printed to obtain a section to be scanned, wherein the section to be scanned is one or more closed polygons; and

[0022] The scanning sequence control module is used to select part or all of at least one polygon as the area to be processed, and scan the area to be processed using the following strategy:

[0023] Fill the interior of the area to be processed with fill lines;

[0024] All fill lines f(k) (k=1, 2, ...m) that are close to or connected to the outline of the polygon are parallel to each other;

[0025] The parallel filling lines f(k) are scanned and sorted so that the endpoint of a later scanned filling line that is close to or connected to the contour cannot exceed the adjacent previously scanned filling line.

[0026] The present invention further provides a powder bed fusion device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of any one of the above methods when executing the computer program.

[0027] The present invention further provides a computer device, comprising a memory and a processor, wherein the memory stores a computer program, wherein the processor implements the steps of any one of the above methods when executing the computer program.

[0028] The present invention further provides a computer-readable storage medium having a computer program stored thereon, and when the computer program is executed by a processor, the steps of any one of the above methods are implemented.

[0029] The laser scanning method for a powder bed fusion process of the present invention comprises: slicing a part to be printed to obtain a cross-section to be scanned, wherein the cross-section to be scanned is one or more closed polygons; selecting part or all of at least one polygon as a region to be processed, and scanning the region to be processed using the following strategy: filling the interior of the region to be processed with a filling line; all filling lines f(k) (k=1, 2, ...m) close to or connected to the contour boundary of the polygon are parallel to each other; scanning and sorting the above-mentioned mutually parallel filling lines f(k) so that the endpoint of the end of the filling line scanned later that is close to or connected to the contour cannot exceed the adjacent filling line scanned previously; so that the present invention can accurately control the shape of the molten pool formed by the filling line by controlling the scanning order of the filling lines that are connected to or close to the contour, especially the molten pool shape at the head and tail of the scanning line, so that the molten pool formed by the filling line scanned later can be attached to one side of the molten pool formed by the previous scan to the greatest extent, which is beneficial to the control of the local temperature gradient of the molten pool, and thus forming a perfect molten pool shape; thereby effectively improving the surface quality and density of the molded part, and suppressing local warping (especially at the contour). BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 A method flow chart is provided for the laser scanning method for powder bed fusion process of the present invention;

[0031] Figure 2 The working example of the laser scanning method for powder bed fusion process provided by the present invention is Figure 1 ;

[0032] Figure 3 The working example of the laser scanning method for powder bed fusion process provided by the present invention is Figure 2 ;

[0033] Figure 4 The working example of the laser scanning method for powder bed fusion process provided by the present invention is Figure 3 ;

[0034] Figure 5 The working example of the laser scanning method for powder bed fusion process provided by the present invention is Figure 4 ;

[0035] Figure 6 The working example of the laser scanning method for powder bed fusion process provided by the present invention is Figure 5 ;

[0036] Figure 7 The working example of the laser scanning method for powder bed fusion process provided by the present invention is Figure 6 ;

[0037] Figure 8 Another working state diagram of the first embodiment of the laser scanning method for powder bed fusion process provided by the present invention;

[0038] Figure 9 The working example 2 of the laser scanning method for powder bed fusion process provided by the present invention Figure 1 ;

[0039] Figure 10 The working example 2 of the laser scanning method for powder bed fusion process provided by the present invention Figure 2 ;

[0040] Figure 11 The working example 2 of the laser scanning method for powder bed fusion process provided by the present invention Figure 3 ;

[0041] Figure 12 The working example 2 of the laser scanning method for powder bed fusion process provided by the present invention Figure 4 ;

[0042] Figure 13 The working example 2 of the laser scanning method for powder bed fusion process provided by the present invention Figure 5 ;

[0043] Figure 14 Another working state diagram of embodiment 2 of the laser scanning method for powder bed fusion process provided by the present invention. DETAILED DESCRIPTION

[0044] In order to make the purpose, technical solutions and advantages of this application more clear, the following further describes this application in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0045] The scanning method of the prior art does not limit the order of the scanning lines, which often leads to local melt pool morphology, thereby affecting the surface quality and density of the printed parts. The inventors of the present application have discovered through creative work that if the filling lines inside each layer of the slice of the part to be printed can be sorted, that is, the filling lines whose ends (including the head and tail) are close to or connected to the contour are controlled, the ends of the scanned lines of the later scanned lines cannot exceed the previous scanned lines adjacent to them, that is, the shape of the melt pool formed by the filling lines can be accurately controlled, especially the melt pool shape at the head and tail of the scan lines, so that the melt pool formed by the later scanned filling lines can be attached to one side of the melt pool formed by the previous scan to the greatest extent, which is beneficial to the control of the local temperature gradient of the melt pool, and then form a perfect melt pool shape; thereby, the surface quality and density of the molded parts can be effectively improved, and local warping (especially at the contour) can be suppressed.

[0046] like Figure 1 As shown, the laser scanning method for powder bed fusion process provided by the present invention comprises the following steps:

[0047] Step 1: Slice the part to be printed to obtain a section to be scanned, where the section to be scanned is one or more closed polygons;

[0048] Step 2: Select part or all of at least one polygon as the area to be processed, and scan the area to be processed using the following strategy:

[0049] The interior of the area to be processed is filled with fill lines; all fill lines f(k) (k=1, 2, ...m) that are close to or connected to the outline of the polygon are parallel to each other;

[0050] The parallel filling lines f(k) are scanned and sorted so that the endpoint of a later scanned filling line that is close to or connected to the contour cannot exceed the adjacent previously scanned filling line.

[0051] The area to be processed here can be all polygons or part of the polygons of the section to be scanned, or it can be part of the area or all of all selected polygons, or part of the area or all of selected part of the polygons. The specific area can be determined according to actual needs. Of course, preferably, the area to be processed here can be the entire area of ​​all polygons of the section to be scanned.

[0052] In order to enable those skilled in the art to better understand and implement the technical solution of the present invention, the technical solution of the present invention is described in detail below in the form of embodiments.

[0053] Example 1

[0054] The laser scanning method for the powder bed fusion process of this embodiment includes the following steps:

[0055] Step 11: Slice the part to be printed to obtain a section to be scanned. The section to be scanned is one or more closed polygons, such as Figure 2 As shown;

[0056] Step 12: Fill the interior of each polygon with a fill line scan vector, select the entire area of ​​at least one polygon as the area to be processed, and all fill lines f(k) (k=1, 2, ...m) that are close to or connected to the outline boundary of the area to be processed are parallel to each other, such as Figure 3 As shown (it should be noted that the figure only shows the scanning strategy of one polygon, and the scanning strategies of other polygons are executed with reference to it); wherein, the filling line close to or connected to the contour boundary is a filling line whose endpoint is within 0.5mm from the contour. It should be noted that in this step, the specific meaning of all the filling lines f(k) (k=1, 2, ...m) that are close to or connected to the contour boundary being parallel to each other is: 1. The endpoints of all the filling lines close to the contour are either directly connected to the contour, or the distance from the contour is less than or equal to 0.5mm; 2. The filling line of the inner center of each polygon (that is, the central area away from the contour) may not be parallel to the filling line close to the contour, such as Figure 3 As shown, of course, all the filling lines within the polygon can also be set to be parallel to each other; third, the length of the parallel filling lines close to the outline is not specifically limited in this application, and can be set according to other parameter requirements such as the area of ​​the polygon.

[0057] Step 13: Scan and sort the parallel filling lines f(k) so that the endpoint of the later scanned filling line that is close to or connected to the contour cannot exceed the adjacent previously scanned filling line. Figure 8 As shown, Figure 8 In the figure, A1 and A2 are a group of adjacent filling lines, and B1 and B2 are another group of adjacent filling lines. Through the implementation of the scheme of the present application, the parallel filling lines f(k) are reasonably controlled for scanning sorting, so that the end point of the later scanned filling line A2 connected to the contour does not exceed the previously scanned filling line A1, that is, a perpendicular line is drawn from the end point of the filling line A2 connected to the contour to the filling line A1, and its foot is located within the filling line A1; similarly, the end point of the later scanned filling line B2 connected to the contour does not exceed the previously scanned filling line B1, that is, a perpendicular line is drawn from the end point of the filling line B2 connected to the contour to the filling line B1, and its foot is located within the filling line B1.

[0058] It should be noted that the innovation of the present invention is to sort the scanning order of the filling lines within the contour, and the scanning order of the contour is not limited. Therefore, it can be scanned using any method of the existing technology, which will not be elaborated here.

[0059] As a preferred embodiment of the present invention, the above Figure 3 The scanning and sorting of the mutually parallel filling lines f(k) specifically includes the following steps:

[0060] Step 31: Create a pair of unit vectors with opposite directions perpendicular to the parallel filling lines, defined as like Figure 3 As shown; it should be noted here that, Figure 3 Although only one polygon's fill line layout is shown in the figure, it should be noted that the fill line settings of other polygons can be set separately according to this scheme. Of course, the fill line directions of different polygons can be the same or different.

[0061] Step 32: Take any point on each edge of the area to be processed and draw a unit vector through the point that is parallel to f(k) and points to the interior of the part to be printed. according to The direction of is parallel to the edge, and Obtain described is the unit vector of the edge; that is, by making Satisfies the conditions: its direction is parallel to the contour segment i, and Right now and The angle does not exceed 90 degrees to obtain like Figure 4 As shown;

[0062] Step 33: When one of the filling lines f(k) is close to or connected to two edges of the area to be processed, calculate the unit vectors of the two edges. and and The product of the product of the numbers, if Then the filling line is divided into two or more than two, and n new filling lines f′(k) (k=1, 2, ...n) (n≥m) that are close to or connected to the contour are obtained, and each filling line is close to or connected to only one edge of the area to be processed, such as Figure 5 As shown; preferably, the filling line can be divided into two, and the dividing point is the midpoint of the filling line, which is convenient for processing. Of course, in a specific implementation, part of the filling line can be divided into two, and part of the filling line can also be divided into multiple lines, for example, three, etc., which is not limited here.

[0063] Step 34: For each fill line in the fill line f′(′), the unit vector of the only side of the polygon close to or connected to the fill line is Respectively Find the dot product if Then determine the sort vector of the filling line as Otherwise, the sort vector of the fill line is determined as like Figure 6 As shown;

[0064] Step 35: Group the adjacent filling lines with the same sorting vector into a scanning group, and scan the filling lines in the same scanning group in sequence according to the direction of their sorting vectors. Figure 7 As shown, the filling lines in the polygon can be divided into four scanning groups, and the scanning order of the filling lines in each scanning group is as follows: Figure 7 shown.

[0065] As one of the further preferred embodiments of the present invention, when the profile includes two or more scan groups, the two or more scan groups are separated by or For example, in this embodiment, the scanning can be performed in the order of B, D, C, and A.

[0066] As a second further preferred solution of the present invention, when a contour includes two or more scanning groups, the two or more scanning groups can be scanned in the order of the contour lines they belong to, such as in the present embodiment, in the order of A, B, C, D.

[0067] Of course, in specific implementations, other scanning orders may also be used between the scanning groups, which is not limited in this application.

[0068] Example 2

[0069] The laser scanning method for the powder bed fusion process of this embodiment includes the following steps:

[0070] Step 21: Slice the part to be printed to obtain a section to be scanned, where the section to be scanned is one or more closed polygons;

[0071] Step 22: Fill the interior of each polygon with a fill line scan vector, and select at least one partial area of ​​the polygon as the area to be processed (the area to be processed is shown in FIG. Figure 9 The area surrounded by the bottom bold outline of the polygon), and all the filling lines f(k) (k=1, 2, ...m) that are at least close to or connected to the outline boundary of the area to be processed are parallel to each other.

[0072] Step 23: Scan and sort the parallel filling lines f(k) so that the end point of the filling line scanned later that is close to or connected to the contour cannot exceed the adjacent filling line scanned earlier. Figure 14 As shown, Figure 14In the figure, A1 and A2 are a group of adjacent filling lines, and B1 and B2 are another group of adjacent filling lines. Through the implementation of the scheme of the present application, the parallel filling lines f(k) are reasonably controlled for scanning sorting, so that the end point of the later scanned filling line A2 connected to the contour does not exceed the previously scanned filling line A1, that is, a perpendicular line is drawn from the end point of the filling line A2 connected to the contour to the filling line A1, and its foot is located within the filling line A1; similarly, the end point of the later scanned filling line B2 connected to the contour does not exceed the previously scanned filling line B1, that is, a perpendicular line is drawn from the end point of the filling line B2 connected to the contour to the filling line B1, and its foot is located within the filling line B1.

[0073] right Figure 9 The scanning and sorting of the mutually parallel filling lines f(k) specifically includes the following steps:

[0074] Step 41: Create a pair of unit vectors with opposite directions perpendicular to the parallel filling lines, defined as like Figure 9 As shown;

[0075] Step 42: Take any point on each edge of the area to be processed and draw a unit vector through the point that is parallel to f(k) and points to the interior of the part to be printed. according to The direction of is parallel to the edge, and Obtain described is the unit vector of the edge; that is, by making Satisfies the conditions: its direction is parallel to the contour segment i, and Right now and The angle does not exceed 90 degrees to obtain like Figure 10 As shown;

[0076] Step 43: When one of the fill lines f(k) is close to or connected to two edges of the area to be processed, calculate the unit vectors of the two edges. and and The product of the product of the numbers, if Then the filling line is divided into two or more than two, and n new filling lines f′(k) (k=1, 2, ...n) (n≥m) that are close to or connected to the contour are obtained, and each filling line is close to or connected to only one edge of the area to be processed, such as Figure 11 shown.

[0077] Step 44: For each fill line in the fill line f′(k), the unit vector of the only side of the polygon close to or connected to the fill line is Respectively Find the dot product if Then determine the sort vector of the filling line as Otherwise, the sort vector of the fill line is determined as like Figure 12 As shown;

[0078] Step 45: Group the adjacent filling lines with the same sorting vector into a scanning group, and scan the filling lines in the same scanning group in sequence according to the direction of their sorting vectors. Figure 13 As shown, the filling lines of the area to be processed within the polygon can be divided into three scanning groups, and the scanning order of the filling lines of each scanning group is as follows: Figure 13 As shown, group C has only one scan vector and is not limited.

[0079] As one of the further preferred embodiments of the present invention, when the profile includes two or more scan groups, the two or more scan groups are separated by or For example, in this embodiment, the scanning can be performed in the order of A, B, and C.

[0080] As a second further preferred solution of the present invention, when the contour includes two or more scanning groups, the two or more scanning groups can be scanned in the order of the contour lines they belong to, such as in the present embodiment, in the order of B, A, and C.

[0081] Of course, in specific implementations, other scanning orders may also be used between the scanning groups, which is not limited in this application.

[0082] The present invention also provides a laser scanning device for a powder bed fusion process, the device comprising:

[0083] a slicing module for slicing the part to be printed to obtain a section to be scanned, wherein the section to be scanned is one or more closed polygons; and

[0084] The scanning sequence control module is used to select part or all of at least one polygon as the area to be processed, and scan the area to be processed using the following strategy:

[0085] The interior of the area to be processed is filled with fill lines; all fill lines f(k) (k=1, 2, ...m) that are close to or connected to the outline of the polygon are parallel to each other;

[0086] The parallel filling lines f(k) are scanned and sorted so that the endpoint of a later scanned filling line that is close to or connected to the contour cannot exceed the adjacent previously scanned filling line.

[0087] The present invention further provides a powder bed fusion device, comprising a memory, a processor, and a computer program stored in the memory and runnable on the processor, characterized in that the processor implements the steps of the method described in any of the above embodiments when executing the computer program.

[0088] The present invention further provides a computer device, comprising a memory and a processor, wherein the memory stores a computer program, wherein the processor implements the steps of the method described in any one of the above embodiments when executing the computer program.

[0089] The present invention further provides a computer-readable storage medium having a computer program stored thereon, and when the computer program is executed by a processor, the steps of the method described in any one of the above embodiments are implemented.

[0090] The technical features of the above embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification. The above-mentioned embodiments only express several implementation methods of the present application. The description is relatively specific and detailed, but it cannot be understood as a limitation on the scope of the invention patent. It should be pointed out that for ordinary technicians in this field, without departing from the concept of the present application, several variations and improvements can be made, which all fall within the scope of protection of the present application. Therefore, the scope of protection of the patent of this application shall be based on the attached claims.

Claims

1. A laser scanning method for powder bed fusion process, characterized in that: include: Slicing the part to be printed to obtain a section to be scanned, where the section to be scanned is one or more closed polygons; Select part or all of at least one polygon as the area to be processed, and scan the area to be processed using the following strategy: Fill the interior of the area to be processed with fill lines; All filling lines f(k) (k=1, 2, ...m) that are close to or connected to the contour boundary of the polygon are parallel to each other; the above-mentioned parallel filling lines f(k) are scanned and sorted so that the endpoint of the later scanned filling line that is close to or connected to the contour cannot exceed the adjacent previously scanned filling line.

2. The laser scanning method for powder bed fusion process according to claim 1, characterized in that: Scanning and sorting the parallel filling lines f(k) specifically includes the following steps: Step 31: Create a pair of unit vectors with opposite directions perpendicular to the parallel filling lines, defined as Step 32: Take any point on each edge of the area to be processed and draw a unit vector through the point that is parallel to f(k) and points to the interior of the part to be printed. according to The direction of is parallel to the edge, and ≥0 to obtain described is the unit vector of the edge; Step 33: When one of the filling lines f(k) is close to or connected to two edges of the area to be processed, calculate the unit vectors of the two edges. and and The product of the product of the numbers, if Then the fill line is divided into two or more, and new n fill lines f are obtained that are close to or connected to the contour. ' (k) (k = 1, 2, ... n) (n ≥ m), and each filling line is close to or connected to only one edge of the area to be processed; Step 34: Fill line f ' For each fill line in (k), the unit vector of the only side of the polygon close to or connected to the fill line is Respectively Find the dot product if Then determine the sort vector of the filling line as Otherwise, the sort vector of the fill line is determined to be - Step 35 : Group adjacent filling lines with the same sorting vector into a scanning group, and scan the filling lines in the same scanning group in sequence according to the direction of their sorting vectors.

3. The laser scanning method for powder bed fusion process according to claim 1 or 2, characterized in that: When the profile contains two or more scan groups, the two or more scan groups are separated by or- Scan in sequence in the following directions.

4. The laser scanning method for powder bed fusion process according to claim 1 or 2, characterized in that: The filling line close to or connected to the outline boundary is a filling line whose endpoint is within 0.5 mm from the outline.

5. The laser scanning method for powder bed fusion process according to claim 2, characterized in that: In step 33, the filling line is divided into two, and the dividing point is the midpoint of the filling line.

6. A laser scanning device for powder bed fusion process, characterized in that: The device comprises: a slicing module for slicing the part to be printed to obtain a section to be scanned, wherein the section to be scanned is one or more closed polygons; and The scanning sequence control module is used to select part or all of at least one polygon as the area to be processed, and scan the area to be processed using the following strategy: Fill the interior of the area to be processed with fill lines; All fill lines f(k) (k=1, 2, ...m) that are close to or connected to the outline of the polygon are parallel to each other; The parallel filling lines f(k) are scanned and sorted so that the endpoint of a later scanned filling line that is close to or connected to the contour cannot exceed the adjacent previously scanned filling line.

7. A powder bed fusion apparatus comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 5 are implemented.

8. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 5 are implemented.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 5 are implemented.

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