Large-layer-thickness additive manufacturing method and application thereof

Abstract

The invention relates to the field of additive manufacturing, in particular to a large-layer-thickness additive manufacturing method and application thereof. The method comprises the following steps: (a) slicing a three-dimensional model, and setting the thickness of a printing layer; (b) setting entity filling scanning parameters and contour scanning parameters; and (c) according to the parameters set in the step (b), laser scanning is carried out on each powder layer, and contour scanning is carried out at least twice and comprises first contour scanning carried out before entity filling scanning and second contour scanning carried out after entity filling scanning. According to the method, the manufacturing efficiency is remarkably improved on the basis of ensuring the forming precision; by setting two types of parameters of filling and contour, collaborative optimization is carried out on the internal metallurgy quality and the surface forming quality, and splashing is reduced from the source; according to the method, at least two times of contour scanning with a clear sequence are stipulated, a molten pool boundary is formed before entity filling to constrain splashing and stabilize the contour, and then modification is carried out after entity filling to eliminate defects and improve the smoothness.

Description

Technical Field

[0001] This invention relates to the field of additive manufacturing, and more specifically, to a method for additive manufacturing with large layer thickness and its application. Background Technology

[0002] Additive manufacturing, especially selective laser melting (SLM) technology, has been widely used in aerospace, medical devices and other fields because it can directly form complex metal parts. This technology involves slicing a three-dimensional model into layers and then selectively melting metal powder layer by layer using a high-energy laser beam, ultimately creating a dense part.

[0003] In industrial applications, printing efficiency and cost are key considerations. Increasing the thickness of a single layer (i.e., using a high-layer-thickness process) is one of the effective ways to improve efficiency and reduce costs. Conventional SLM processes typically have a layer thickness between 30 and 60 μm to balance forming quality and efficiency. The so-called high-layer-thickness process generally refers to increasing the layer thickness to 80-120 μm or even higher, in order to significantly reduce the total number of layers and shorten printing time.

[0004] However, increased layer thickness presents new challenges to process control. To ensure that a sufficiently thick powder layer is completely melted and to avoid fatal defects such as incomplete fusion between layers, the laser energy input during solid filling scanning must be significantly increased, typically manifested as the use of higher laser power. This high-power solid filling scanning induces intense molten pool dynamics, generating a large amount of spatter. This spatter falls onto the surface of the forming contour or surrounding areas, forming adhesion defects upon cooling. Simultaneously, high energy input also degrades the stability of the solid filling molten pool, making its edges prone to irregular serrations, severely degrading the surface roughness and dimensional accuracy of the part, such as... Figure 1 As shown.

[0005] To address surface quality issues, existing technologies typically employ strategies that optimize contour scanning parameters. For example, smooth boundaries are achieved by individually adjusting the power and speed of the contour scan. However, in the context of processes involving large layer thickness and high-power solid fill, simply adjusting contour parameters yields minimal results. The energy of the contour scan is insufficient to effectively remove or remelt the large amounts of spatter and irregular edges generated by high-energy solid fill, failing to achieve the surface quality required for the application. Furthermore, some technical solutions utilize multi-pass contour scanning to improve the surface finish.

[0006] Therefore, existing technologies lack an effective method to systematically solve the severe surface defects caused by high-power solid filling in additive manufacturing processes with large layer thicknesses of 80-120μm. How to effectively control spatter and refine contours to obtain the required surface quality while ensuring internal metallurgical quality (avoiding incomplete fusion) through innovative combinations of process parameters and scanning strategies has become a critical technical bottleneck that urgently needs to be overcome in this field.

[0007] In view of this, the present invention is hereby proposed. Summary of the Invention

[0008] This invention addresses the surface quality control problem in large-layer-thickness additive manufacturing processes by providing a method and its application. It achieves this by controlling laser forming process parameters from multiple dimensions, including solid filling parameters, contour parameters, the spacing between the contour line and the solid filling line, and the number of contour line scans. This comprehensive adjustment of surface defect influencing factors reduces surface defects.

[0009] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted: One aspect of the present invention relates to a method for additive manufacturing with large layer thickness, comprising the following steps: (a) Slice the 3D model and set the printing layer thickness; (b) Set the entity fill scan parameters and contour scan parameters; (c) Perform laser scanning on each powder layer according to the parameters set in step (b), wherein the contour scanning is performed at least twice, including a first contour scan performed before the solid filling scan and a second contour scan performed after the solid filling scan.

[0010] The aforementioned large-layer-thickness additive manufacturing method directly increases the amount of material processed per layer by setting the printing layer thickness, significantly improving manufacturing efficiency while ensuring forming accuracy. By setting two types of parameters, namely fill and contour, the internal metallurgical quality and surface forming quality are synergistically optimized, reducing spatter from the source. By specifying at least two contour scans in a clear order, the molten pool boundary is formed before the solid fill to constrain spatter and stabilize the contour, and then the solid fill is used for finishing to eliminate defects and improve surface finish. Thus, under the condition of high efficiency and large layer thickness, the industry problem of difficult surface quality is overcome in one fell swoop.

[0011] Another aspect of the present invention relates to an additive manufacturing apparatus, including a memory and a processor, the memory storing a computer program, the processor executing the computer program to implement the steps of the large-layer-thickness additive manufacturing method.

[0012] Another aspect of the invention relates to a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the large-layer-thickness additive manufacturing method.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows: The large-layer-thickness additive manufacturing method provided by this invention suppresses spatter from the source by co-optimizing solid filling parameters and adopts a multi-pass, specific-bias contour scanning strategy to perform a systematic "pre-melting-filling-stabilizing-finishing" process on the edges. This successfully maintains the process efficiency and internal metallurgical quality of large-layer-thickness materials of 80~120μm while significantly reducing surface defects, thereby achieving high-efficiency and high-surface-quality large-layer-thickness additive manufacturing. Attached Figure Description

[0014] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0015] Figure 1 This is a demonstration image illustrating the poor surface quality of existing high-layer-thickness printing processes. Figure 2 This is a schematic diagram of the slice lines; Figure 3 Four comparative fluorescence detection defect images are shown. Figure 4 The images show the fluorescence detection results for five examples. Detailed Implementation

[0016] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0017] One aspect of the present invention relates to a method for additive manufacturing with large layer thickness, comprising the following steps: (a) Slice the 3D model and set the printing layer thickness; (b) Set the entity fill scan parameters and contour scan parameters; (c) Perform laser scanning on each powder layer according to the parameters set in step (b), wherein the contour scanning is performed at least twice, including a first contour scan performed before the solid filling scan and a second contour scan performed after the solid filling scan.

[0018] The aforementioned large-layer-thickness additive manufacturing method achieves a systematic improvement in three aspects: efficiency, quality, and process controllability. First, by setting the printing layer thickness, the processing volume per layer is directly increased, significantly improving manufacturing efficiency while ensuring forming accuracy. Second, by setting two types of parameters—filling and contour—internal metallurgical quality and surface forming quality are synergistically optimized, reducing spatter from the source. Finally, by specifying at least two contour scans in a clear order, the molten pool boundary is formed before the solid filling to constrain spatter and stabilize the contour, and then the solid filling is used for finishing to eliminate defects and improve surface finish. Thus, under highly efficient large-layer-thickness conditions, the industry problem of achieving unsatisfactory surface quality is overcome in one fell swoop.

[0019] Furthermore, the thickness of the printed layer is 80~120μm, including but not limited to a point value of any one of 80μm, 90μm, 100μm, 110μm, or 120μm, or a range between any two. The additive manufacturing method provided by this invention mainly targets large-thickness printed layers of 80~120μm. While ensuring achievable powder spreading and penetration, it significantly improves single-layer processing efficiency, achieving a reliable leap from conventional layer thickness to high-efficiency large-thickness printing, and is the foundation for achieving the overall process cost reduction and efficiency improvement goals.

[0020] Further, the entity filling scanning parameters include: a scanning power of 350~450W (for example, it can be any one of 350W, 360W, 370W, 380W, 390W, 400W, 410W, 420W, 430W, 440W or 450W or any range between two), a scanning speed of 800~1200mm / s (for example, it can be any one of 800mm / s, 850mm / s, 900mm / s, 1000mm / s, 1050mm / s, 1100mm / s, 1150mm / s or 1200mm / s or any range between two), and a scanning spacing of 0.09~0.11mm (for example, it can be any one of 0.09mm, 0.10mm or 0.11mm or any range between two). By limiting the power, speed, and scanning spacing of solid filling within a co-optimized range, while ensuring the penetration of thick powder layers and avoiding incomplete fusion defects, excessive spatter and molten pool instability caused by excessive power are effectively suppressed, thereby reducing the generation of major surface defects from the source.

[0021] The present invention's approach to adjusting solid filling parameters aims to reduce spatter generated during solid filling scanning. This requires controlling the solid filling laser power to avoid excessive levels, minimizing power while ensuring metallurgical quality and tolerance. Simultaneously, energy density can be maintained by reducing scanning speed and scanning spacing.

[0022] Further, the contour scanning parameters include: a scanning power of 270~340W (e.g., a point value or a range between any two of 270W, 280W, 290W, 300W, 310W, 320W, 330W, or 340W), and a scanning speed of 450~600mm / s (e.g., a point value or a range between any two of 450mm / s, 460mm / s, 470mm / s, 480mm / s, 490mm / s, 500mm / s, 510mm / s, 520mm / s, 530mm / s, 540mm / s, 550mm / s, 560mm / s, 570mm / s, 580mm / s, 590mm / s, or 600mm / s). Setting a lower power and a matching lower speed for contour scanning aims to form a stable and energy-concentrated molten pool. This parameter combination enhances the ability of the contour molten pool to capture and remelt spatter, and provides a controllable process window for implementing multi-pass scanning, which is the core of improving edge surface quality.

[0023] Furthermore, the offset distance between the trajectory of the first contour scan and the solid filling scan area is 0~0.02mm, including but not limited to point values ​​of any one of 0mm, 0.01mm, or 0.02mm, or a range between any two. The first contour scan trajectory is set to be offset inward by 0~0.02mm, making it closely adhere to the solid filling boundary. This pre-forms a narrow and shallow molten pool boundary before solid filling, acting as a "dam" to help constrain the subsequent flow of the solid filling molten pool, reducing the disorderly outward spread of molten metal and the splashing of spatter into the contour area.

[0024] Furthermore, the trajectory of the second contour scan is set outside the trajectory of the first contour scan, and the offset distance between them is 0~0.02mm, including but not limited to point values ​​of any one of 0mm, 0.01mm, or 0.02mm, or a range between any two. The second contour scan trajectory is specified to be offset 0~0.02mm outside the first contour. This design allows the second contour to remelt and absorb the area between the first contour and the solid fill edge, effectively handling potential defects such as spatter adhesion, incomplete fusion, or geometric irregularities in this area, thereby widening and stabilizing the forming basis of the final contour.

[0025] Furthermore, the contour scan is performed 2 to 4 times, including but not limited to point values ​​from any one of 2, 3, or 4 scans, or a range of values ​​between any two. Limiting the number of contour scans to 2 to 4 times provides the process with flexibility to meet different surface quality requirements. Users can achieve an optimal balance between efficiency (fewer scans) and ultimate surface quality (more scans).

[0026] The approach to adjusting the contour parameters in this invention is to enhance the ability of contour scanning to handle edge spatter. This involves increasing laser power and scanning speed to control the stability of the molten pool. The offset distance between the contour line and the filler line of the workpiece is adjusted; too large an offset distance can easily lead to near-surface incomplete fusion or surface voids, while too small an offset distance can result in surface nodules and excess material. The contour is scanned 2-4 times (efficiency must be considered). The first scan forms a molten pool, followed by scanning the solid filler line, and finally, a final contour scan refines the boundary molten pool. The second contour scan is offset further outwards to absorb powder and form a stable molten pool.

[0027] Furthermore, when the contour scan is executed 3 to 4 times, the contour scan includes: a first contour scan executed before the solid filling scan and a second, third, and fourth contour scan executed after the solid filling scan; wherein the trajectory of the third contour scan coincides with that of the second contour scan, and the trajectory of the fourth contour scan coincides with that of the second contour scan.

[0028] In the large-layer-thickness additive manufacturing method described above, other parameters such as upper surface parameters, lower surface parameters, and support parameters can be conventional parameters in the field, and the present invention does not impose specific limitations.

[0029] In some specific embodiments, the large-layer-thickness additive manufacturing method includes the following steps: (1) Model design and repair: Use modeling software to complete the three-dimensional modeling of the parts, repair the three-dimensional model through slicing software, add support structures to enhance printing stability; slice the three-dimensional model; (2) Parameter setting and model slicing: Set laser parameters according to material properties, including: printing layer thickness, solid filling parameters, contour parameters, upper surface parameters, lower surface parameters and support parameters; (3) Printing process: The doctor blade spreads the powder evenly onto the molding substrate to form a single layer of powder; the laser beam scans each powder layer layer by layer according to the slice data, and the contour scan is performed at least twice, including the first contour scan performed before the solid infill scan and the second contour scan performed after the solid infill scan. The powder is locally melted by the laser scan to form a molten pool. After the molten pool solidifies rapidly, it combines with the lower layer and is stacked layer by layer to form the final shape.

[0030] Furthermore, the modeling software includes any one of CAD, SolidWorks, or UG.

[0031] Furthermore, the slicing software includes 3DLayer and / or Magics.

[0032] Another aspect of the present invention relates to an additive manufacturing apparatus, including a memory and a processor, the memory storing a computer program, the processor executing the computer program to implement the steps of the large-layer-thickness additive manufacturing method.

[0033] Another aspect of the invention relates to a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the large-layer-thickness additive manufacturing method.

[0034] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0035] Examples 1-5 The large-layer-thickness additive manufacturing method provided in Examples 1-5 includes the following steps: (1) Use modeling software to complete the 3D model of the part, repair the 3D model using slicing software, and add support structures to enhance printing stability; slice the 3D model, such as... Figure 2 As shown; (2) Set the laser parameters according to the material properties. The specific settings are shown in Table 1, including: printing layer thickness, solid filling parameters, contour parameters, upper surface parameters, lower surface parameters and support parameters, etc. Except for printing layer thickness, solid filling parameters and contour parameters, the other parameters are conventional parameters. Table 1

[0036] (3) The scraper spreads the powder evenly onto the molding substrate to form a single layer of powder; the laser beam scans each powder layer layer by layer according to the slice data, so that the powder is locally melted to form a molten pool. After the molten pool solidifies quickly, it combines with the lower layer and is stacked layer by layer to form the shape. The contour scan is performed at least twice, including a first contour scan performed before the solid filling scan and a second contour scan performed after the solid filling scan. The trajectory of the second contour scan is set outside the trajectory of the first contour scan.

[0037] Comparative Example 1: Excessive Solid Filling Power The only difference between this comparative example and Example 1 is that the scanning power of the solid filling scanning parameters is 460W.

[0038] Comparative Example 2: Excessive Entity Fill Scanning Speed The only difference between this comparative example and Example 1 is that the scanning speed of the solid filling scanning parameters is 1250 mm / s.

[0039] Comparative Example 3 uses only a single-layer profile The only difference between this comparative example and Example 1 is that it uses only a single-pass profile.

[0040] Comparative Example 4 has a larger profile offset. The only difference between this comparative example and Example 1 is that the offset distance between the trajectory of the first contour scan and the solid filling scan area is 0.05 mm.

[0041] Experimental Example The fluorescence detection results of the ratio and examples are as follows Figure 3 and Figure 4 As shown, by Figure 3 and Figure 4 It can be known that: The number of defects in Example 1 is 2, the number of defects in Example 2 is 1, the number of defects in Example 3 is 0, the number of defects in Example 4 is 2, and the number of defects in Example 5 is 0. Comparative Example 1: The solid filling power is too high, and the corresponding spatter size is larger. The large slag particles on the edge cannot be completely melted by the contour molten pool, which will randomly form surface defects, with a defect size of about 24. Comparative Example 2: When the solid filling scanning speed is too high, the molten pool becomes unstable, resulting in a corresponding increase in slag shedding and an increased probability of surface defects, with a defect rate of approximately 13.

[0042] Comparative Example 3: Using only a single-layer profile, the single-layer profile cannot completely melt the slag produced by the solid filling, while the double-layer profile can melt large particles of spatter through remelting, and the defect is about 60.

[0043] Comparative Example 4: The contour offset is large. Since the solid filling edge is actually uneven, the liquid melted in the contour is not enough to completely fill the concave part, forming a large number of surface defects, with defects of about 90%.

[0044] Although the present invention has been illustrated and described with specific embodiments, it should be understood that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; those skilled in the art should understand that modifications can be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein, without departing from the spirit and scope of the present invention; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A large layer thickness additive manufacturing method, characterized by, The method comprises the following steps: (a) slicing a three-dimensional model and setting a printing layer thickness; (b) setting a solid filling scanning parameter and a contour scanning parameter; (c) performing a laser scanning on each powder layer according to the parameter set in step (b), wherein the contour scanning is performed at least twice, including a first contour scanning performed before the solid filling scanning and a second contour scanning performed after the solid filling scanning.

2. The large layer thickness additive manufacturing method of claim 1, wherein, The printing layer thickness is 80-120 μm.

3. The large layer thickness additive manufacturing method of claim 1, wherein, The solid filling scanning parameter comprises a scanning power of 350-450 W, a scanning speed of 800-1200 mm / s and a scanning interval of 0.09-0.11 mm.

4. The large layer thickness additive manufacturing method of claim 1, wherein, The contour scanning parameter comprises a scanning power of 270-340 W and a scanning speed of 450-600 mm / s.

5. The large layer thickness additive manufacturing method of claim 1, wherein, The first contour scanning track is offset from the solid filling scanning area by a distance of 0-0.02 mm.

6. The large layer thickness additive manufacturing method of claim 1, wherein, The second contour scanning track is set outside the first contour scanning track, and the offset distance between the two tracks is 0-0.02 mm.

7. The large layer thickness additive manufacturing method of claim 1, wherein, The contour scanning is performed 2-4 times.

8. The large layer thickness additive manufacturing method of claim 7, wherein, When the contour scanning is performed 3-4 times, the contour scanning comprises a first contour scanning performed before the solid filling scanning, a second contour scanning, a third contour scanning and a fourth contour scanning performed after the solid filling scanning, wherein the third contour scanning track coincides with the second contour scanning track, and the fourth contour scanning track coincides with the second contour scanning track.

9. An additive manufacturing apparatus comprising a memory and a processor, the memory storing a computer program, characterized in that, The processor executes the computer program to implement the steps of the large layer thickness additive manufacturing method according to any one of claims 1-8.

10. A computer-readable storage medium having stored thereon a computer program, characterized in that, The computer program is executed by the processor to implement the steps of the large layer thickness additive manufacturing method according to any one of claims 1-8.

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