Selective laser melting method and system

Abstract

The invention discloses a selective laser melting method and system, and relates to the technical field of additive manufacturing. The selective laser melting method comprises the following steps that a part model created by 3D software is obtained, and whether a rib beam and / or a supporting piece are / is machined or not is judged based on the part model; the slicing software obtains the part model, divides the part model into two-dimensional layers and selects different scanning strategies; the temperature control module preheats the substrate to a set temperature; and based on the selected scanning strategy, laser is used for melting powder layer by layer till part machining is completed. The dimensional stability of the component is improved by selecting different scanning strategies, the rib beam is machined to reduce the deformation risk so as to enhance the mechanical property, and the supporting piece is machined to improve the stability of the printing process.

Description

Technical Field

[0001] The present application relates to the field of additive manufacturing, and in particular to a selective laser melting method and system. Background Art

[0002] During the selective laser melting (SLM) forming process of high-temperature alloys, due to uneven thermal stress and cooling rate, ribs, thin walls and lattice structures are prone to deformation, affecting the precision and performance of the formed parts; the deformation of these structures is mainly due to the uneven distribution of thermal stress and the temperature gradient caused by rapid cooling, resulting in local shrinkage or warping.

[0003] As the application of additive manufacturing technology in high-precision fields such as aerospace continues to expand, the requirements for accuracy and stability are becoming more stringent. Summary of the invention

[0004] To solve the above problems, the present application discloses a selective laser melting method, which improves the dimensional stability of the component by selecting different scanning strategies, reduces the risk of deformation by processing the ribs and thus enhances the mechanical properties, and improves the stability of the printing process by processing the support parts; at the same time, a corresponding selective laser melting system is proposed to realize the selective laser melting method provided by the present application.

[0005] The first technical solution adopted in this application is: providing a selective laser melting method, comprising the following steps: Obtaining a part model created by 3D software, and determining whether to process the rib beam and / or the support member based on the part model; The slicing software obtains the part model and divides it into two-dimensional layers and selects different scanning strategies; the temperature control module preheats the substrate to a set temperature; Based on the selected scanning strategy, the laser is used to melt the powder layer by layer until the part is completed.

[0006] The temperature control module is arranged on a side of the substrate away from the processing surface, and the temperature control module continuously obtains temperature data of the substrate, and adjusts the temperature of the substrate to a set temperature based on the temperature data.

[0007] The scanning strategies include circumferential scanning, unidirectional scanning and interlayer rotation scanning. Different scanning strategies are selected based on different part models to optimize the temperature field and stress distribution.

[0008] The scanning strategy further includes dividing the part model into a plurality of part modules to reduce the thermal load on the module components.

[0009] The temperature control module can be divided into a plurality of sub-temperature control modules, and the plurality of sub-temperature control modules correspond to a plurality of part modules one by one to obtain temperature data.

[0010] Among them, different rib-beam structures are processed based on the part model, and the rib-beam structures include variable cross-sections, transition sections or gradual changes; and thermal stress concentration is reduced based on the selected different rib-beam structures.

[0011] Wherein, the support member is processed based on the part model; the support member is arranged at the connection between the rib beam and the part model to enhance stability.

[0012] The method further includes removing the support member after the part model is processed.

[0013] The second technical solution adopted in the present application is to provide a selective laser melting system for implementing the selective laser melting method as described in any one of the above items, comprising: A temperature control module, wherein the temperature control module is used to obtain temperature data of the substrate; Laser scanning system: operates based on the set scanning strategy; Data processing unit: used to process the 3D model data and convert it into multiple slice layers; A control unit is connected to the temperature control module and the laser scanning system, and is used to obtain temperature data of the temperature control module and adjust the working state of the laser scanning system.

[0014] Wherein, the temperature control module comprises: The temperature control panel is divided into zones, and each zone is equipped with a hollow metal spiral coil; A temperature detection device is installed in each partition to monitor the substrate temperature in each partition in real time; A temperature control component, the temperature control component includes a control cabinet, a water cooler and a partition channel valve, and the temperature control component is used to adjust the temperature of each partition.

[0015] The beneficial effects of this application are as follows:

[0016] 1. The temperature control module can accurately control the temperature of the substrate during processing, effectively reduce thermal stress and deformation, and improve component processing accuracy and quality.

[0017] 2. Select different scanning strategies based on different part models to improve the dimensional stability of components.

[0018] 3. Divide large-scale part models into multiple part modules to reduce the heat load on individual module components and reduce overall deformation caused by thermal stress.

[0019] 4. Set up support parts to ensure the stability of ribs and large-size areas during printing to avoid deformation caused by external forces or thermal stress. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. Among them: Figure 1 A schematic diagram of a process flow of an embodiment of a selective laser melting method provided in the present application; Figure 2 A schematic structural diagram of an embodiment of a part model provided in this application; Figure 3 A schematic diagram of a framework of an embodiment of a selective laser melting system provided in the present application; Figure 4 for Figure 3 A schematic diagram of the framework of an embodiment of a medium temperature control module. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. It will be appreciated that the specific embodiments described herein are only used to explain the present application, rather than to limit the present application. It should also be noted that, for ease of description, only some but not all structures related to the present application are shown in the drawings. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the art without making creative work are within the scope of protection of the present application.

[0022] The terms "first", "second", etc. in this application are used to distinguish different objects, rather than to describe a specific order. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally includes steps or units that are not listed, or optionally includes other steps or units inherent to these processes, methods, products or devices.

[0023] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0024] In order to improve the accuracy of the model generated by selective laser melting (SLM) processing to meet the existing standards of high-precision fields such as aerospace, the deformation of the part model should be reduced during the selective laser melting process; the present application provides a selective laser melting method, such as Figure 1 As shown, Figure 1 The schematic diagram of the process of an embodiment of the selective laser melting method provided in the present application includes the following steps: Step S11: Obtain a part model created by 3D software. The 3D software may be SolidWorks or AutoCAD, etc., and there is no limitation on this. The part model should include all necessary geometric information and structural details of the part to be processed, so as to facilitate subsequent processing and analysis.

[0025] Based on the part model, determine whether to process ribs and / or supports, and conduct a detailed analysis of the part model to determine which areas need to add ribs to enhance the structural strength, and which locations may require supports to avoid deformation due to overhang or tilt; based on the analysis results, adjust the original design if necessary, such as adding ribs or designing appropriate supports. The design of these ribs and supports needs to consider their impact on the final part performance and how to minimize the risk of deformation during the printing process.

[0026] Step S12: The slicing software obtains the part model and divides it into two-dimensional layers and selects different scanning strategies; the slicing software will cut the three-dimensional part model into a series of continuous two-dimensional cross-sectional layers along the Z-axis direction according to the set layer thickness parameters; according to the specific structural features of the part model (such as ribs, thin walls and lattice structures), the most suitable laser scanning path and mode are selected in the slicing software.

[0027] The temperature control module preheats the substrate to a set temperature. The specific value of the set temperature is not limited here. For example, the set temperature is 200°C±5°C. It should be clear that the set temperature is a temperature range rather than a single temperature value, so as to reduce the working frequency of the temperature control module and reduce the burden. Preheating the substrate can balance heat input and output, prevent thermal stress concentration caused by local overheating or inconsistent cooling speed, and thus reduce the risk of warping and cracking; a uniform and stable substrate temperature environment is conducive to maintaining good adhesion and flatness between layers.

[0028] Step S13: Based on the selected scanning strategy, the powder is melted layer by layer by laser until the part is processed; the selected scanning strategy uses a high-precision laser beam to scan the laid metal powder layer layer by layer along a predetermined path. The laser energy causes the powder material to melt locally and tightly combine with the next layer; after each layer is printed, the workbench will drop a certain distance, and the distance dropped each time is the set layer thickness; a new powder layer is laid, and the above process is repeated until the entire part is processed.

[0029] By precisely controlling the energy input and scanning path of the laser, fine control of each layer can be achieved, thereby ensuring the dimensional accuracy and shape accuracy of the final part; by adjusting the scanning strategy, various complex manufacturing tasks can be flexibly responded to according to different types of parts and their special requirements, meeting diverse design needs.

[0030] It should be clarified that the powder can be high temperature alloy powder, titanium alloy powder or stainless steel powder, etc., without any limitation.

[0031] In summary, the selective laser melting method of this embodiment includes the following steps: obtaining the part model created by 3D software, judging whether to process the ribs and / or supports based on the part model; the slicing software obtains the part model and divides it into two-dimensional layers and selects different scanning strategies; the temperature control module preheats the substrate to the set temperature; based on the selected scanning strategy, the laser is used to melt the powder layer by layer until the part processing is completed. By selecting different scanning strategies, the dimensional stability of the component is improved, the processing of the ribs reduces the risk of deformation and thus enhances the mechanical properties, and the processing of the supports improves the stability of the printing process.

[0032] Optionally, the temperature control module is arranged on a side of the substrate away from the processing surface, and the temperature control module is arranged on a side of the substrate away from the processing surface to ensure that it can effectively heat or cool the substrate.

[0033] The temperature control module continuously obtains the temperature data of the substrate. The temperature data can be obtained through the temperature sensor and sent to the control unit; the temperature of the substrate is adjusted to the set temperature based on the temperature data. If the substrate temperature is higher than the set temperature, the temperature control module cools the substrate; if the substrate temperature is lower than the set temperature, the temperature control module heats the substrate.

[0034] The temperature control module can accurately control the temperature of the substrate during processing, effectively reducing thermal stress and deformation, and improving component processing accuracy and quality.

[0035] Optionally, the scanning strategies include circumferential scanning, unidirectional scanning and interlayer rotation scanning. Different scanning strategies are selected based on different part models to optimize the temperature field and stress distribution. Different scanning strategies are selected based on different part models. The part models applicable to each scanning strategy are described below: Circular scanning: Applicable to circular or ring structures, helps to evenly distribute heat.

[0036] One-way scanning: suitable for long strips or rectangular areas, simplifying path planning.

[0037] Inter-layer rotation scanning optimizes the temperature field and stress distribution by changing the scanning direction between different layers. It is suitable for large flat areas or when heat accumulation needs to be reduced.

[0038] Different scanning strategies can help achieve a more uniform heating and cooling process, thereby avoiding problems caused by local overheating or inconsistent cooling rates, such as warping and cracking; through reasonable scanning path design, the thermal stress generated during the manufacturing process can be effectively dispersed and the risk of deformation caused by stress concentration can be reduced.

[0039] Optionally, the scanning strategy further includes dividing the part model into a plurality of part modules to reduce the heat load on the module components; the steps of dividing the part model into a plurality of part modules are described in detail below: Perform a comprehensive analysis of the part model to identify areas that are prone to concentrated thermal loads and deformation risks due to oversize or complex shapes.

[0040] Based on the analysis results, large-sized or complex-structured parts are reasonably divided into several small modules. The design of each module should keep its internal structure relatively simple to reduce the heat load on a single module and ensure that the connection between modules is convenient for subsequent assembly.

[0041] Select the most suitable scanning strategy for each module and adjust the processing parameters (such as laser power, scanning speed, layer thickness, etc.) according to specific needs to achieve optimal control of temperature field and stress distribution.

[0042] During the processing, each module is manufactured separately, and the temperature changes and stress distribution are closely monitored. If necessary, corresponding adjustments are made to ensure the quality of each module.

[0043] After all modules are printed, they are assembled precisely according to the design to form a complete part, followed by necessary post-processing operations such as surface treatment and heat treatment.

[0044] By splitting large parts into smaller modules, the heat load on the overall structure can be effectively dispersed, local overheating can be avoided, and the risk of deformation caused by thermal stress can be reduced; small modules are easier to control, which helps to improve the manufacturing precision of each part, thereby ensuring the dimensional accuracy and shape stability of the entire part; if a problem occurs in a module, only the module needs to be remanufactured instead of the entire part, reducing resource waste and time costs.

[0045] Optionally, the temperature control module can be divided into multiple sub-temperature control modules, and the multiple sub-temperature control modules correspond to multiple part modules one by one to obtain temperature data; each part module is configured with a corresponding sub-temperature control module to ensure that each sub-temperature control module can work independently and accurately control the temperature of its own responsible area. In this way, the temperature of different modules can be finely managed; the control unit will continuously monitor the data of each sub-temperature control module to ensure that the temperature of the area where each part module is located remains stable.

[0046] By equipping each part module with a dedicated sub-temperature module, highly precise control of the temperature in a specific area can be achieved, effectively avoiding the problem of thermal stress concentration caused by local overheating or inconsistent cooling speeds. Different part modules may have different heat requirements, and independent sub-temperature modules can flexibly adjust their respective heating or cooling rates according to actual needs, optimize the overall heat distribution, and reduce the risk of deformation.

[0047] It should be clarified that in this embodiment, the sub-temperature control modules correspond one-to-one to the parts modules. In other embodiments, multiple sub-temperature control modules correspond to a single parts module or a single sub-temperature control module corresponds to multiple parts modules. There is no limitation on this.

[0048] The following describes in detail the parameters of an embodiment of selective laser melting of large-sized metal components: The temperature control module is divided into 5 sub-temperature control modules, each of which includes 3 temperature sensors, which are used to monitor the temperature of the substrate; the set temperature is 200°C±5°C.

[0049] The scanning strategies selected were circumferential scanning and interlayer rotation scanning, where the interlayer rotation angle was set to 67°; laser parameter adjustment: laser power was set to 350 W, scanning speed was 1000 mm / min, and layer thickness was 0.05 mm.

[0050] The ribbed beam structure adopts a variable cross-section design, and a transition section is designed in the ribbed beam area with a length set to 20 mm to gradually change the cross-section and reduce thermal stress concentration.

[0051] The large-size structure is divided into 10 part modules, that is, one sub-temperature control module corresponds to two part modules, and the heat load borne by each module does not exceed 20% of the set value.

[0052] like Figure 2 As shown, Figure 2 A schematic structural diagram of an embodiment of a part model provided in the present application, including a skin, a lattice, ribs, depressions and linear defects.

[0053] In order to reduce the mass of the structure and achieve the purpose of lightweighting, the outside of the structure is usually covered with a thin-walled structure with a thickness of 1 mm, which is called a skin.

[0054] The lattice adopts a four-bar structure, which on the one hand reduces the mass of the structure and achieves the purpose of lightweighting; on the other hand, it provides support for the skin to prevent macroscopic skin buckling deformation.

[0055] The stiffness of thin-walled structures is relatively low, and the overall stiffness of the structure is mainly contributed by the ribs and beams.

[0056] Due to the existence of the ribs, a large cross-sectional change occurs during slicing, resulting in uneven macroscopic stress distribution of the parts, a large shrinkage occurs at the rib position, and ultimately a macroscopic depression is formed.

[0057] Linear defects refer to linear flaws that appear inside or on the surface of a material due to various factors during the manufacturing process.

[0058] Optionally, different rib beam structures are processed based on the part model, and the rib beam structures include variable cross-sections, transition sections or gradual changes; thermal stress concentration is reduced based on the selected different rib beam structures; the effects obtained by the different rib beam structures are described in detail below: Variable cross-section design: Introducing variable cross-section design into the ribbed beam structure, that is, gradually increasing or decreasing the thickness of the ribbed beam at certain locations; variable cross-section design helps to disperse stress and avoid local stress concentration.

[0059] Transition section design: Adding a transition section at the connection between the rib beam and the main structure or other components makes the connection between the two smoother, thereby reducing stress concentration points caused by sudden changes.

[0060] Gradual variation design: For long reinforced beams or beams with complex shapes, a gradual variation design concept is adopted to ensure that the stiffness and strength of the entire reinforced beam structure are evenly distributed, further reducing the risk of stress concentration.

[0061] Based on different part models, select one or more most suitable combinations of different rib beam structures; at the same time, consider how to integrate these designs into the overall part design to ensure that they can enhance the structural strength without affecting part printing.

[0062] The rib beam not only enhances the overall rigidity and bending resistance of the parts, but also improves their ability to resist external loads, especially when subjected to dynamic loads. Compared with the traditional design, the optimized rib beam structure can reduce unnecessary material usage, reduce costs and reduce weight while ensuring or even improving structural performance.

[0063] Optionally, support parts are processed based on the part model; support parts are set at the connection between the rib beam and the part model to enhance stability; the slicing software analyzes the part model, determines whether to process support parts based on the analysis results, and designs the position of support parts at the connection between the rib beam and the part model or other key positions; support parts should be placed in places that can effectively disperse stress and provide sufficient support. The specific shape and size of the support parts are designed according to actual needs. The support structure includes columnar support, mesh support, and adaptive support, etc., and no restrictions are made on this.

[0064] Setting supports at the connection between the rib beam and the part model can significantly enhance the mechanical stability of the area and prevent structural deformation due to gravity or uneven material flow; the presence of supports enables the part to maintain the correct shape during the printing process, helping to achieve higher dimensional accuracy and better surface finish.

[0065] Optionally, the selective laser melting method also includes removing supports after the part model is processed. Removing supports can not only significantly improve the surface quality and functional performance of the part, but also reduce material waste, optimize manufacturing costs, and ensure that the part can meet various stringent industrial standards and application requirements.

[0066] The present application also provides a selective laser melting system for implementing the selective laser melting method of any of the above embodiments; Figure 3 As shown, Figure 3 A schematic diagram of a framework of an embodiment of a selective laser melting system provided in the present application, including a temperature control module, a laser scanning system, a data processing unit and a control unit; The temperature control module is used to obtain temperature data of the substrate; the temperature control module controls the working state of the temperature control component based on the obtained temperature data and thus adjusts the temperature of the substrate.

[0067] The laser scanning system is connected to the control unit and receives the scanning strategy, and the laser scanning system operates based on the set scanning strategy.

[0068] The data processing unit is used to process the three-dimensional model data and convert it into multiple slice layers; the data processing unit is connected to the control unit and sends data such as the slice layers and scanning strategies to the control unit.

[0069] The control unit is connected to the temperature control module and the laser scanning system. The control unit is used to obtain the temperature data of the temperature control module and adjust the working state of the laser scanning system. The operation of the laser scanning system will increase the temperature of the substrate. The temperature data obtained by the temperature control module is then used to adjust the working state of the laser scanning system through the control unit to achieve negative feedback control.

[0070] like Figure 4 As shown, Figure 4 for Figure 3 A schematic diagram of a framework of an embodiment of a medium temperature control module includes: The temperature control board is arranged in zones, and the temperature control board is arranged at the bottom of the base plate; each zone is provided with a hollow metal spiral coil; A temperature detection device is installed in each partition to monitor the substrate temperature in each partition in real time; The temperature control component includes a control cabinet, a water cooler and a partition channel valve. The temperature control component is used to adjust the temperature of each partition.

[0071] The temperature control principle of the temperature control assembly of this embodiment is described in detail below: If the temperature detection device detects that the temperature of a certain partition is too high, it sends a signal to the control cabinet, and the control cabinet controls the working status of the water cooler and the partition channel valve; that is, turn on the water cooler and open the channel valve to the partition, and the cooling water flows into the hollow metal spiral coil to keep cooling until the temperature of the partition remains normal.

[0072] In the several embodiments provided in this application, it should be understood that the disclosed methods and devices can be implemented in other ways. For example, the device implementation described above is only illustrative, for example, the division of the modules or units is only a logical function division, and there may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed.

[0073] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the present embodiment.

[0074] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0075] The above description is only an implementation method of the present application, and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly used in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A selective laser melting method, characterized in that: The steps include: Obtaining a part model created by 3D software, and determining whether to process the rib beam and / or the support member based on the part model; The slicing software obtains the part model and divides it into two-dimensional layers and selects different scanning strategies; the temperature control module preheats the substrate to a set temperature; Based on the selected scanning strategy, the laser is used to melt the powder layer by layer until the part is completed.

2. The selective laser melting method according to claim 1, characterized in that: The temperature control module is arranged on a side of the substrate away from the processing surface. The temperature control module continuously obtains temperature data of the substrate and adjusts the temperature of the substrate to a set temperature based on the temperature data.

3. The selective laser melting method according to claim 2, characterized in that: The scanning strategies include circumferential scanning, unidirectional scanning and interlayer rotation scanning. Different scanning strategies are selected based on different part models to optimize the temperature field and stress distribution.

4. The selective laser melting method according to claim 3, characterized in that: The scanning strategy also includes dividing the part model into a plurality of part modules to reduce the thermal load borne by the module components.

5. The selective laser melting method according to claim 4, characterized in that: The temperature control module can be divided into a plurality of sub-temperature control modules, and the plurality of sub-temperature control modules correspond to a plurality of part modules one by one to obtain temperature data.

6. The selective laser melting method according to claim 5, characterized in that: Different rib beam structures are processed based on the part model, wherein the rib beam structures include variable cross-sections, transition sections or gradual changes; and thermal stress concentration is reduced based on the selected different rib beam structures.

7. The selective laser melting method according to claim 6, characterized in that: A support member is processed based on the part model; the support member is arranged at the connection between the rib beam and the part model to enhance stability.

8. The selective laser melting method according to claim 7, characterized in that: The method also includes removing the support member after the part model is processed.

9. A selective laser melting system, used to implement the selective laser melting method according to any one of claims 1 to 8, characterized in that: include: A temperature control module, wherein the temperature control module is used to obtain temperature data of the substrate; Laser scanning system: operates based on the set scanning strategy; Data processing unit: used to process the 3D model data and convert it into multiple slice layers; A control unit is connected to the temperature control module and the laser scanning system, and is used to obtain temperature data of the temperature control module and adjust the working state of the laser scanning system.

10. The selective laser melting system according to claim 9, characterized in that: The temperature control module comprises: The temperature control panel is divided into zones, and each zone is equipped with a hollow metal spiral coil; A temperature detection device is installed in each partition to monitor the substrate temperature in each partition in real time; A temperature control component, the temperature control component includes a control cabinet, a water cooler and a partition channel valve, and the temperature control component is used to adjust the temperature of each partition.

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