Dynamic scanning method and device for laser sintering and additive manufacturing equipment

Abstract

The invention discloses a dynamic scanning method and device for laser sintering and additive manufacturing equipment, and the dynamic scanning method for laser sintering comprises the steps that the section contour of a current layer of a working area is divided into two or more areas, and the areas close to the contour are subjected to laser scanning through Gaussian light spots A, carrying out laser scanning on an area far away from the contour by adopting a binormal light spot B; wherein the size ratio Rb: Ra of the Gaussian light spot A to the binormal light spot B belongs to (1.2, 5); the maximum energy of the Gaussian light spot A is Amax, and the minimum energy of the Gaussian light spot A is Amin; the highest energy of the binormal light spot B is Bmax, and the lowest energy of the binormal light spot B is Bmin; the Amaxt is 0.65 Amaxt; bmaxt, Bmaxt; the Amax is 0.95 Amax, and the Bmax is 0.5 Bmax; b min < lt >; and Bmax. According to the dynamic scanning method and device for laser sintering and the additive manufacturing equipment, partition scanning and light spot energy adjustment are combined, and the printing quality and the workpiece performance are guaranteed while the printing efficiency is improved.

Description

Technical Field

[0001] The present application relates to the field of additive manufacturing technology, and in particular to a dynamic scanning method, device and additive manufacturing equipment for laser sintering. Background Art

[0002] Additive manufacturing technology is a rapid manufacturing technology that forms three-dimensional objects by controlling the laser to scan layer by layer and stacking layer by layer. The process flow is as follows: first, the three-dimensional model of the workpiece is sliced ​​to obtain the contour information of each layer of the workpiece; the powdered material is evenly spread on the surface of the work platform, and the laser selectively melts the powder according to the system instructions; after a section is completed, a new layer of material is spread, and the scanning continues to be selective according to the section information corresponding to the three-dimensional object; according to this method, the next section is scanned for powder spreading, and finally a three-dimensional object is obtained.

[0003] The current selective laser melting (SLM) process (one of the additive manufacturing technologies) mainly uses the traditional Gaussian spot, which has a normal energy distribution, with a high energy density in the center and a gradually decreasing energy density at the edge. Although this energy distribution can meet most processing needs, it has significant limitations for the following application scenarios: 1. Heat concentration problem: For heat-sensitive materials, excessive laser power can easily cause warping and deformation, resulting in printing failure. 2. High-reflectivity material restrictions: High-reflectivity metal materials such as aluminum alloys and copper alloys have poor adaptability to the energy distribution of Gaussian spots, and the material absorption efficiency is low, which affects the molding quality. 3. Printing of large and complex structures: As the size and complexity of parts increase, the printing time is greatly extended, and the equipment may be interrupted due to external factors such as exhaustion of protective gas, lens contamination, and power failure, which significantly affects the printing stability. 4. Melt pool stability: Although increasing the spot size can increase the printing speed, it will reduce the stability of the melt pool and increase the surface roughness.

[0004] In order to solve the above problems, the printing efficiency is usually improved by increasing the number of lasers or optimizing the scanning path, but these measures may increase equipment costs or introduce new quality problems such as processing instability. Therefore, how to improve efficiency while ensuring printing quality has become a core issue in the research of additive manufacturing technology. Summary of the invention

[0005] In order to solve the above-mentioned technical problems existing in the prior art, the present invention provides a dynamic scanning method, device and additive manufacturing equipment for laser sintering. The dynamic scanning method for laser sintering combines partition scanning with spot energy adjustment, thereby improving printing efficiency while ensuring printing quality and workpiece performance.

[0006] In order to achieve the above object, the present invention provides a dynamic scanning method for laser sintering, comprising the following steps:

[0007] The current layer cross-sectional contour of the working area is divided into two or more areas, and the area close to the contour is laser scanned using Gaussian spot A, and the area far from the contour is laser scanned using binormal spot B; wherein,

[0008] The size ratio of Gaussian spot A and binormal spot B is Rb:Ra∈(1.2,5);

[0009] The maximum energy of Gaussian spot A is Amax, and the minimum energy is Amin; the maximum energy of binormal spot B is Bmax, and the minimum energy is Bmin; 0.65Amax <Bmax<0.95Amax,0.5Bmax<Bmin<Bmax。

[0010] As a further preferred embodiment of the present invention, when the current layer cross-sectional contour of the working area is divided into two areas, the area close to the contour is laser scanned using a Gaussian spot A, and the area far from the contour is laser scanned using a binormal spot B, specifically including:

[0011] The current layer cross-sectional contour of the working area is divided into region A and region B by using a virtual contour, wherein region A is the region surrounded by the actual contour of the current layer cross-sectional contour and the virtual contour, and region B is all regions surrounded by the virtual contour, wherein the virtual contour has the same shape as the actual contour, and the area of ​​the virtual contour is smaller than the area of ​​the actual contour;

[0012] Area A is scanned using Gaussian spot A, and area B is scanned using binormal spot B.

[0013] As a further preferred solution of the present invention, the area B is first scanned using a binormal spot B, and then the area A is scanned using a Gaussian spot A.

[0014] As a further preferred embodiment of the present invention, the width of the region A is a, a∈(4Ra, 10mm).

[0015] As a further preferred embodiment of the present invention, when the current layer cross-sectional contour of the working area is divided into two or more regions, the area close to the contour is laser scanned using a Gaussian spot A, and the area far from the contour is laser scanned using a binormal spot B, specifically including:

[0016] The current layer cross-sectional contour of the working area is divided into several areas along the longitudinal or transverse direction of the working area, and Gaussian spot A is used to perform laser scanning on two areas close to the contour, and binormal spot B is used to perform laser scanning on at least one area far from the contour.

[0017] As a further preferred embodiment of the present invention, when the current layer cross-sectional profile of the working area is divided into more than two regions, Gaussian spot A is used for laser scanning in the regions close to the profile, and double-normal spot B is used for laser scanning in the regions far from the profile. Specifically, it includes:

[0018] Determine the centroid position of the current layer cross-sectional profile of the working area. With this centroid as the center, use several "square" shapes of different sizes to divide the current layer cross-sectional profile into several regions from the inside out. Starting from the regions close to the profile, switch and scan Gaussian spot A and double-normal spot B alternately for each adjacent region.

[0019] As a further preferred embodiment of the present invention, the spacing between adjacent "squares" is the same.

[0020] As a further preferred embodiment of the present invention, the filling power, filling speed, and filling spacing of Gaussian spot A and double-normal spot B respectively satisfy the following conditions:

[0021] Filling power: 0.7Pb ≤ Pa ≤ 0.9Pb;

[0022] Filling speed: 0.9Sb ≤ Sa ≤ Sb;

[0023] Filling spacing: 0.6Db ≤ Da ≤ 0.9Db;

[0024] Wherein, Pa is the filling power of Gaussian spot A, Pb is the filling power of double-normal spot B, Sa is the filling speed of Gaussian spot A, Sb is the filling speed of double-normal spot B, Da is the filling spacing of Gaussian spot A, and Db is the filling spacing of double-normal spot B.

[0025] The present invention also provides a dynamic scanning device for an additive manufacturing device, including a memory and a processor. The memory stores a computer program. It is characterized in that when the processor executes the computer program, it realizes the steps of the dynamic scanning method for laser sintering described in any one of the above.

[0026] The present invention also provides an additive manufacturing device, which includes the dynamic scanning device of the additive manufacturing device described above.

[0027] The dynamic scanning method, device, and additive manufacturing device for laser sintering of the present invention significantly improve the efficiency and quality of laser additive manufacturing by combining dynamic spot regulation and zonal scanning, and specifically include the following beneficial effects:

[0028] 1. The dynamic scanning strategy effectively optimizes the utilization rate of the spot and significantly shortens the printing time of large and complex workpieces;

[0029] 2. Precise energy control and zonal design reduce stress concentration and warping deformation;

[0030] 3. By adjusting the spot energy, the central energy density can be reduced, the heat concentration effect can be reduced, and at the same time, the forming ability for highly reflective materials and complex workpieces can be improved, so as to meet the forming requirements of highly reflective materials and complex geometric parts.

[0031] 4. Provide single-cut and multi-cut dynamic scanning strategy modes, which can cover printing scenarios from small-sized fine structures to large-sized complex structures. Description of the Drawings

[0032] Figure 1 It is a schematic diagram of the energy distribution of the Gaussian spot A and the double-normal spot B of the present invention;

[0033] Figure 2 It is a scanning schematic diagram of Embodiment 1 provided by the dynamic scanning method for laser sintering of the present invention;

[0034] Figure 3 It is a scanning schematic diagram of Embodiment 2 provided by the dynamic scanning method for laser sintering of the present invention;

[0035] Figure 4 It is a scanning schematic diagram of Embodiment 3 provided by the dynamic scanning method for laser sintering of the present invention; Detailed Embodiments

[0036] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0037] The dynamic scanning method for laser sintering provided by the present invention includes the following steps:

[0038] Divide the current layer cross-sectional profile of the working area into two or more regions, and use the Gaussian spot A for laser scanning of the region close to the profile, and use the double-normal spot B for laser scanning of the region far from the profile; wherein,

[0039] The size ratio Rb:Ra of the Gaussian spot A and the double-normal spot B ∈ (1.2, 5);

[0040] The highest energy of the Gaussian spot A is Amax, and the lowest energy is Amin; the highest energy of the double-normal spot B is Bmax, and the lowest energy is Bmin; 0.65Amax < Bmax < 0.95Amax, 0.5Bmax < Bmin < Bmax. The energies of the above Gaussian spot A and double-normal spot B are respectively as Figure 1 shown (the left figure is the Gaussian spot A, and the right figure is the double-normal spot B).

[0041] As an implementation scheme of the present invention, when the current layer cross-sectional profile of the working area is divided into two areas, the area close to the profile is laser scanned using a Gaussian spot A, and the area far from the profile is laser scanned using a binormal spot B, specifically including:

[0042] The current layer cross-sectional contour of the working area is divided into region A and region B by using a virtual contour, wherein region A is the region surrounded by the actual contour of the current layer cross-sectional contour and the virtual contour, and region B is all regions surrounded by the virtual contour, wherein the virtual contour has the same shape as the actual contour, and the area of ​​the virtual contour is smaller than the area of ​​the actual contour;

[0043] Area A is scanned using Gaussian spot A, and area B is scanned using binormal spot B.

[0044] In a specific implementation, the present application does not limit the scanning order of area A (also referred to as A light scanning area) and area B (also referred to as B light scanning area), and either area A or area B can be scanned. As an implementation of the present application, area B can be first scanned using a binormal spot B (also referred to as B light), and then area A can be scanned using a Gaussian spot A (also referred to as A light). Preferably, refer to Figure 2 The width of the area A is a, a∈(4Ra, 10mm). This can avoid overburning of the workpiece and the formation of pores while ensuring the printing efficiency as much as possible, thereby further improving the surface quality of the workpiece.

[0045] As another embodiment of the present invention, when the current layer cross-sectional profile of the working area is divided into two or more areas, the area close to the profile is laser scanned using a Gaussian spot A, and the area far from the profile is laser scanned using a binormal spot B, specifically including:

[0046] The current layer cross-sectional profile of the working area is divided into several regions along the longitudinal or transverse direction of the working area, and two regions close to the profile are laser scanned using Gaussian spot A, and at least one region far from the profile is laser scanned using binormal spot B. Specifically, refer to Figure 3 , the current layer cross-sectional profile can be divided into n+1 and n parts (n=1,2,3…10, n is a natural number) according to the two widths a and b; for example, when n=1, the current layer cross-sectional profile is divided into two areas with a width for Gaussian spot A scanning and one area with a width b for binormal spot B scanning. It can be understood that the value of n can be set according to actual printing requirements. The larger the value of n, the better the effect of reducing heat accumulation, but the printing time will also be longer. Therefore, the specific value of n can be set by the designer according to specific needs, and will not be introduced in detail here.

[0047] As another embodiment of the present invention, when the current layer cross-sectional profile of the working area is divided into more than two regions, Gaussian spot A is used for laser scanning of the regions close to the profile, and double-normal spot B is used for laser scanning of the regions far from the profile. Specifically, it includes:

[0048] Determine the centroid position of the current layer cross-sectional profile of the working area. With this centroid as the center, use several "mouth" shapes of different sizes to divide the current layer cross-sectional profile into several regions from the inside out. Starting from the region close to the profile, switch and scan Gaussian spot A and double-normal spot B for each adjacent region in turn. Specifically, cyclic scanning can be performed in the order of Gaussian spot A, double-normal spot B, Gaussian spot A, double-normal spot B... until the scanning of the current layer cross-sectional profile is completed.

[0049] Specifically, let the scanning widths of the regions for Gaussian spot A scanning and the regions for double-normal spot B scanning be Da and Db respectively. By adjusting the values of Da and Db, the number of divided regions can be controlled; the lower the value, the more regions are divided. In this way, the phenomenon of internal stress concentration can be well reduced, but correspondingly, the printing time will also increase.

[0050] For irregular printing layers, the galvanometer system still scans along the original "mouth" - shaped route. The laser does not emit light in the printing area outside the route, and the laser emits light again after scanning to the printing area.

[0051] Preferably, the spacing between adjacent "mouth" shapes is the same, and Rb:Ra = 2. Because the same spacing will make the heat input distribution of two adjacent laser beams relatively uniform during the scanning process, avoiding excessive heat concentration in a certain direction, thereby reducing the risk of local overheating or thermal deformation. In this way, the possibility of defects such as surface depressions or ripples can be reduced. Moreover, the consistent spacing can also make the scanning process more coherent, reduce the pauses during multiple switches, thereby improving the processing efficiency and reducing the risks that the software may generate due to excessive partitioning.

[0052] Further preferably, in order to improve the forming efficiency and reduce the risk of molten pool instability at the same time, the filling power, filling speed, and filling spacing of Gaussian spot A and double - normal spot B respectively meet the following conditions:

[0053] Filling power: 0.7Pb ≤ Pa ≤ 0.9Pb;

[0054] Filling speed: 0.9Sb ≤ Sa ≤ Sb;

[0055] Filling spacing: 0.6Db ≤ Da ≤ 0.9Db;

[0056] Among them, Pa is the filling power of Gaussian spot A, Pb is the filling power of binormal spot B, Sa is the filling speed of Gaussian spot A, Sb is the filling speed of binormal spot B, Da is the filling spacing of Gaussian spot A, and Db is the filling spacing of binormal spot B.

[0057] The present invention also provides a dynamic scanning device for additive manufacturing equipment, comprising a memory and a processor, wherein the memory stores a computer program, and wherein the processor implements the steps of the dynamic scanning method for laser sintering described in any of the above embodiments when executing the computer program.

[0058] The present invention further provides an additive manufacturing device, which includes the dynamic scanning device of the additive manufacturing device described above.

[0059] 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 through embodiments in combination with the accompanying drawings.

[0060] Embodiment 1

[0061] The dynamic scanning method for laser sintering of this embodiment includes the following steps:

[0062] Step 11, dividing the current layer cross-sectional contour of the working area into two or more areas;

[0063] Step 12: using a virtual contour to divide the current layer cross-sectional contour of the working area into region A and region B, wherein region A is the region surrounded by the actual contour of the current layer cross-sectional contour and the virtual contour, and region B is all regions surrounded by the virtual contour, wherein the virtual contour has the same shape as the actual contour, and the area of ​​the virtual contour is smaller than the area of ​​the actual contour;

[0064] Step 13: first scan area B with a binormal spot B, and then scan area A with a Gaussian spot A. The width of area A is a=0.5 mm; Figure 2 As shown,

[0065] The sizes of Gaussian spot A and binormal spot B are Ra=30um and Rb=60um respectively;

[0066] The maximum energy of Gaussian spot A is Amax, and the minimum energy is Amin; the maximum energy of binormal spot B is Bmax, and the minimum energy is Bmin; 0.65Amax <Bmax<0.95Amax,0.5Bmax<Bmin<Bmax。

[0067] The dynamic scanning method of the first embodiment can also be called a "single-cut" dynamic scanning strategy, that is, the light spot is switched only once. For high-reflectivity materials, this embodiment can reduce the reflection of laser energy and improve energy utilization, thereby improving printing quality and reducing damage to the printing system; for small-sized and high-precision consumer electronic workpieces, it can improve detail resolution on the basis of speed increase to ensure the printing accuracy of small and fine structures; for small and medium-sized complex aerospace workpieces with large stress, it can reduce local stress concentration by accurately controlling heat input, thereby improving the mechanical properties and durability of the workpiece.

[0068] Embodiment 2

[0069] The dynamic scanning method for laser sintering of this embodiment includes the following steps:

[0070] Step 21, dividing the current layer cross-sectional contour of the working area into two or more areas;

[0071] Step 22, dividing the current layer cross-sectional contour of the working area into a plurality of regions along the longitudinal or transverse direction of the working area, using Gaussian spot A to perform laser scanning on two regions close to the contour, and using binormal spot B to perform laser scanning on at least one region far from the contour; Figure 3 As shown, the areas of the several regions are not equal. In a specific implementation, the areas of the several regions may be equal; wherein,

[0072] The sizes of Gaussian spot A and binormal spot B are Ra=70um and Rb=150um respectively;

[0073] The maximum energy of Gaussian spot A is Amax, and the minimum energy is Amin; the maximum energy of binormal spot B is Bmax, and the minimum energy is Bmin; 0.65Amax <Bmax<0.95Amax,0.5Bmax<Bmin<Bmax。

[0074] The dynamic scanning method of the second embodiment can also be called a "multi-cut" dynamic scanning strategy, that is, the light spot is switched twice or more. This embodiment has smaller workpiece stress and higher mechanical properties, prolongs the service life of the workpiece to be printed, and is suitable for printing large-size workpieces.

[0075] Embodiment 3

[0076] The dynamic scanning method for laser sintering of this embodiment includes the following steps:

[0077] Step 31, dividing the current layer cross-sectional contour of the working area into two or more areas;

[0078] Step 32, determine the center of gravity of the current layer cross-sectional contour of the working area, and divide the current layer cross-sectional contour into several regions from the inside to the outside using a number of "mouth" characters of different sizes with the center of gravity as the center. Starting from the region close to the contour, Gaussian spot A and binormal spot B are used to switch and scan each adjacent region in turn; Figure 4 As shown,

[0079] The sizes of Gaussian spot A and binormal spot B are Ra=90um and Rb=400um respectively;

[0080] The maximum energy of Gaussian spot A is Amax, and the minimum energy is Amin; the maximum energy of binormal spot B is Bmax, and the minimum energy is Bmin; 0.65Amax <Bmax<0.95Amax,0.5Bmax<Bmin<Bmax。

[0081] This embodiment and the second embodiment are both called "multi-cut" dynamic scanning strategies, that is, the light spot is switched twice or more. This embodiment has smaller workpiece stress and higher mechanical properties, prolongs the service life of the workpiece to be printed, and is suitable for printing large-size workpieces. In contrast, the scanning strategy of the third embodiment is more suitable for printing workpieces with a complete and regular overall structure, and the workpiece does not have many special structures such as thin walls, sharp corners, and cylinders.

[0082] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.

Claims

1. A dynamic scanning method for laser sintering, characterized in that: It includes the following steps: Divide the current layer cross-sectional profile of the working area into two or more regions. Use Gaussian spot A to perform laser scanning on the region close to the profile, and use double-normal spot B to perform laser scanning on the region far from the profile. Among them, The size ratio Rb:Ra of Gaussian spot A and double-normal spot B ∈ (1.2, 5); The highest energy of Gaussian spot A is Amax, and the lowest energy is Amin; the highest energy of double-normal spot B is Bmax, and the lowest energy is Bmin; 0.65Amax < Bmax < 0.95Amax, 0.5Bmax < Bmin < Bmax.

2. The dynamic scanning method for laser sintering according to claim 1, characterized in that: When the current layer cross-sectional profile of the working area is divided into two regions, using Gaussian spot A to perform laser scanning on the region close to the profile and using double-normal spot B to perform laser scanning on the region far from the profile specifically includes: Use a virtual profile to divide the current layer cross-sectional profile of the working area into region A and region B. Region A is the region surrounded by the actual profile and the virtual profile of the current layer cross-sectional profile, and region B is all the regions surrounded by the virtual profile. The virtual profile has the same shape as the actual profile, and the area of the virtual profile is smaller than the area of the actual profile; Scan region A with Gaussian spot A and scan region B with double-normal spot B.

3. The dynamic scanning method for laser sintering according to claim 2, characterized in that: First scan region B with double-normal spot B, and then scan region A with Gaussian spot A.

4. The dynamic scanning method for laser sintering according to claim 3, characterized in that: The width of region A is a, a ∈ (4Ra, 10mm).

5. The dynamic scanning method for laser sintering according to claim 1, characterized in that: When the current layer cross-sectional profile of the working area is divided into more than two regions, using Gaussian spot A to perform laser scanning on the region close to the profile and using double-normal spot B to perform laser scanning on the region far from the profile specifically includes: Divide the current layer cross-sectional profile of the working area into several regions along the longitudinal or transverse direction of the working area. Use Gaussian spot A to perform laser scanning on the two regions close to the profile, and use double-normal spot B to perform laser scanning on at least one region far from the profile.

6. The dynamic scanning method for laser sintering according to claim 1, characterized in that: When the current layer cross-sectional profile of the working area is divided into more than two regions, using Gaussian spot A to perform laser scanning on the region close to the profile and using double-normal spot B to perform laser scanning on the region far from the profile specifically includes: Determine the centroid position of the current layer cross-sectional profile of the working area. Starting from the centroid, use several "square" shapes of different sizes to divide the current layer cross-sectional profile into several regions from the inside out. Starting from the region close to the profile, switch and scan each adjacent region with Gaussian spot A and double-normal spot B in turn.

7. The dynamic scanning method for laser sintering according to claim 6, characterized in that: The spacing between adjacent "square" shapes is the same.

8. The dynamic scanning method for laser sintering according to any one of claims 1 to 7, characterized in that: The filling power, filling speed, and filling spacing of Gaussian spot A and double-normal spot B respectively satisfy the following conditions: Filling power: 0.7Pb ≤ Pa ≤ 0.9Pb; Filling speed: 0.9Sb ≤ Sa ≤ Sb; Filling Spacing: 0.6Db ≤ Da ≤ 0.9Db; Among them, Pa is the filling power of Gaussian spot A, Pb is the filling power of binormal spot B, Sa is the filling speed of Gaussian spot A, Sb is the filling speed of binormal spot B, Da is the filling spacing of Gaussian spot A, and Db is the filling spacing of binormal spot B.

9. A dynamic scanning device for additive manufacturing equipment, comprising a memory and a processor, wherein the memory stores a computer program, characterized in that: When the processor executes the computer program, the steps of the dynamic scanning method for laser sintering according to any one of claims 1 to 8 are implemented.

10. An additive manufacturing device, characterized in that: A dynamic scanning device comprising the additive manufacturing equipment as described in claim 9.

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