Powder material additive manufacturing method, system and equipment using cooling medium circulation

Abstract

The present application relates to a powder material additive manufacturing method, system and equipment using a cooling medium circulation, the method comprising: slicing and / or partitioning a geometric model of a target component to obtain at least one cooling area including at least a portion of the target component and setting an independent cooling medium control loop for each cooling area; allocating a preset periodic pulse thermal disturbance pattern with a cooling medium flushing frequency and flow rate to at least one cooling area based on at least one cooling area and in combination with real-time temperature distribution and / or process objectives, and applying the pattern to an energy beam scanning process, so that when the energy beam scans the cooling area on a forming base, its corresponding cooling medium control loop is switched to a matching periodic pulse thermal disturbance pattern. By specifically extracting the heat accumulated in the forming base, the cooling rate of the formed part and the molten pool is increased, thereby refining the solidification microstructure and improving the mechanical properties of the formed three-dimensional component.

Description

Technical Field

[0001] The present application relates to the field of additive manufacturing technology, and more specifically to a powder material additive manufacturing method using cooling medium circulation, a cooling medium circulation device, an additive manufacturing device, and an electronic device. Background Art

[0002] The powder material additive manufacturing process uses the interaction of an energy beam with the powder material, causing it to undergo a transient melting process from solid to liquid, followed by a solidification process from liquid to solid. Under program control, the melting and solidification processes are precisely regulated, allowing the powder material to be stacked layer by layer to ultimately form a complex three-dimensional component. Therefore, powder material additive manufacturing is an advanced forming technology that combines a rapid solidification mechanism with the formation of complex structures and even large-scale components.

[0003] In the current additive manufacturing process of powder materials, since the melting and solidification of each layer will impose a new thermal cycle on the formed area of the lower layer, the heat accumulates layer by layer and is transferred to the base material, forming a temperature gradient from top to bottom, so that the entire component maintains a high temperature level during the deposition process. However, in actual processing, due to the long heat conduction path and limited heat extraction efficiency, the temperature of the forming base often gradually increases, resulting in obvious overall heat accumulation in the forming area. In this case, the cooling rate is significantly reduced and the solidification conditions of the molten pool deteriorate. If the heat is not extracted in time, not only will the temperature of the forming base continue to rise, breaking the original temperature gradient, but it will also interfere with the flow and solidification behavior inside the molten pool, resulting in grain coarsening and a decrease in mechanical properties.

[0004] Therefore, how to efficiently and promptly remove accumulated heat during the forming process has become a key factor affecting the quality of powder material additive manufacturing. On the one hand, rapid and effective heat removal helps maintain a large temperature gradient and cooling rate, promoting the formation of fine grains and refining the microstructure, thereby improving the strength and toughness of the component. On the other hand, rationally controlling the heat flow path and heat dissipation mechanism can effectively control the heat-affected zone of each layer during the deposition process, reduce residual stress and thermal deformation, and improve forming accuracy and structural integrity.

[0005] The evolution of microstructure is influenced by many factors, the most critical of which are the local solidification conditions within the molten pool and the overall temperature distribution of the formed body under continuous thermal cycling. These two factors are influenced by both the heat input parameters and the thermal storage effect and heat removal capacity. If heat removal is not timely, not only will the temperature of the forming base continue to rise, disrupting the original temperature gradient and causing a decrease in cooling rate, but it will also interfere with the flow and solidification behavior within the molten pool, resulting in coarsening of the microstructure and ultimately affecting the mechanical properties of the formed three-dimensional component. Summary of the Invention

[0006] The present application provides a powder material additive manufacturing method, system and equipment using cooling medium circulation. It can adopt a pulse circulation mode of cooling medium to provide cooling medium with matching cooling medium flushing frequency and flow rate for each cooling area of the forming base, and specifically extract the heat accumulated in the forming base to increase the temperature gradient and cooling rate inside the formed part and the molten pool, thereby refining the solidification microstructure and improving the mechanical properties of the formed three-dimensional component.

[0007] In the first aspect, the present application provides a powder material additive manufacturing method using cooling medium circulation, the method comprising: slicing and / or partitioning the geometric model of the target component to obtain at least one cooling area including at least a portion of the target component and setting an independent cooling medium control loop for each cooling area; assigning a preset periodic pulse thermal disturbance pattern with a cooling medium flushing frequency and flow rate to the at least one cooling area according to the at least one cooling area and in combination with the real-time temperature distribution and / or process objectives; and applying the periodic pulse thermal disturbance pattern to the energy beam scanning process, so that when the energy beam scans the cooling area on the forming base, its corresponding cooling medium control loop is switched to a matching periodic pulse thermal disturbance pattern.

[0008] In an optional scheme of the first aspect, when slicing the geometric model of the target component, the method includes: obtaining at least one cooling area including at least one layer of the target component based on the layered data of the target component after slicing and setting an independent cooling medium control loop for each layer of the cooling area.

[0009] In an optional solution of the first aspect, during energy beam scanning, the method includes:

[0010] According to the number of target component layers scanned by the energy beam, the cooling medium control loop corresponding to the cooling area of the target component layers is switched to a matching periodic pulse thermal disturbance mode.

[0011] In an optional solution of the first aspect, the periodic pulse thermal disturbance pattern includes a transitional thermal disturbance pattern between at least two cooling regions or a composite thermal disturbance pattern formed by stacking at least two cooling regions.

[0012] In an optional scheme of the first aspect, when allocating a preset periodic pulse thermal disturbance pattern with a cooling medium flushing frequency and flow rate, the method includes: reconstructing the temperature distribution of the cooling area using a two-dimensional instantaneous heat conduction equation based on the collected real-time temperature distribution data; establishing a periodic heat flux model coupled with the molten pool boundary based on the characteristics of the generated pulse cooling medium; establishing a grain growth disturbance model of grain refinement rate, temperature disturbance and gradient based on the periodic heat flux model; constructing a preset optimization function and updating the pulse parameters in real time to maximize the grain refinement rate within a limited time and / or space range.

[0013] In an optional scheme of the first aspect, when reconstructing the temperature distribution of the cooling area, the method includes: defining a two-dimensional transient heat conduction equation and using a two-dimensional Gaussian distribution heat source to simulate the energy beam input; defining the cooling boundary conditions for applying a pulsed cooling medium; discretizing the two-dimensional area into a grid and setting the space and time steps, and then assigning an initial temperature; calculating the position of the energy beam heat source; updating the cooling boundary conditions; updating the temperature value using an explicit finite difference method; and outputting the temperature distribution.

[0014] In an optional scheme of the first aspect, when establishing a periodic heat flux model, the method includes: applying a time-varying heat transfer boundary to the molten pool cooling surface; calculating the Reynolds number and the convection heat transfer coefficient equation according to the change in the cooling medium flow rate to generate the instantaneous heat transfer coefficient of the cooling medium; calculating the cooling heat flux at each moment according to the instantaneous heat transfer coefficient and the cooling medium temperature; applying the cooling heat flux at each moment as a Neumann boundary to the heat conduction equation to update the temperature value using an explicit finite difference method.

[0015] In an optional scheme of the first aspect, when establishing a grain growth perturbation model, the method includes: establishing a refinement differential equation of the refinement rate growth rate and introducing a perturbation enhancement function; obtaining the temperature distribution; calculating the cooling rate and temperature gradient; calculating the perturbation enhancement function based on the flushing frequency and flow rate of the cooling medium; solving the refinement differential equation to generate the grain refinement rate; and outputting the equiaxed crystal ratio field.

[0016] In an optional scheme of the first aspect, when updating the pulse parameters in real time, the method includes: constructing a preset optimization function based on the grain refinement model; using a preset optimization strategy to search for the optimal cooling medium flushing frequency and flow rate to update the pulse parameters; and outputting the updated pulse parameters as a control signal to the corresponding cooling medium control loop.

[0017] In an optional scheme of the first aspect, the method also includes: slicing and / or partitioning the geometric model of the target component to obtain at least one cooling area including at least a portion of the target component and setting an independent cooling medium control loop for each cooling area; assigning a preset periodic pulse thermal disturbance pattern with cooling medium flushing frequency, flow rate and flow direction to the at least one cooling area according to the at least one cooling area and in combination with real-time temperature distribution and / or process objectives; and applying the periodic pulse thermal disturbance pattern to the energy beam scanning process, so that when the energy beam scans to the cooling area on the forming base, its corresponding cooling medium control loop is switched to a matching periodic pulse thermal disturbance pattern.

[0018] In an optional solution of the first aspect, the cooling medium control circuit includes a cooling medium pulse parameter control circuit and a cooling medium flow direction control circuit.

[0019] In the second aspect, the present application provides a cooling medium circulation device for additive manufacturing of powder materials, comprising: a forming base, which is provided with at least one cooling circulation channel; at least one pulse pump, which is connected to the at least one cooling circulation channel, and is used to drive the cooling medium to realize a periodic pulse thermal disturbance mode; a temperature monitoring unit, which is arranged in the forming chamber and the forming base, and is used to collect real-time temperature data; a control unit, which is connected to and controls the at least one pulse pump and the temperature monitoring unit to execute the above-mentioned powder material additive manufacturing method using cooling medium circulation.

[0020] In a third aspect, the present application provides a cooling medium circulation device for powder material additive manufacturing, comprising:

[0021] A forming base is provided with a plurality of cooling circulation channels; a variable guide unit is arranged in the plurality of cooling circulation channels and is used to realize dynamic changes in the direction of the cooling medium; at least one pulse pump is connected to the plurality of cooling circulation channels and is used to drive the cooling medium to realize a periodic pulse thermal disturbance mode; a temperature monitoring unit is arranged in the forming chamber and the forming base and is used to collect real-time temperature data; a control unit is connected to and controls the variable guide unit, the pulse pump and the temperature detection unit to execute the above-mentioned powder material additive manufacturing method using cooling medium circulation.

[0022] In a fourth aspect, the present application provides an additive manufacturing device comprising any of the above-mentioned cooling medium circulation devices.

[0023] In a fifth aspect, the present application provides an electronic device comprising: at least one processor; at least one memory; the at least one memory is coupled to the at least one processor and is used to store instructions executed by the at least one processor, and the instructions, when executed by the at least one processor, enable the electronic device to perform a method according to any one of the above items.

[0024] It should be understood that the foregoing general description and the following detailed description are merely illustrative and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings, which are incorporated herein and form a part of the specification, illustrate one or more embodiments of the present application and, together with the description, serve to explain the principles of the present application and to enable one of ordinary skill in the relevant art to make and use the present application.

[0026] Figure 1 This is a schematic structural diagram of an exemplary forming base with a cooling circulation channel according to some embodiments of the present application.

[0027] Figure 2 This is a scanning schematic diagram of an exemplary powder material additive manufacturing using cooling medium circulation according to some embodiments of the present application.

[0028] Figure 3 This is a comparative schematic diagram of the apparent quality of an exemplary three-dimensional component according to some embodiments of the present application; wherein, ① is a three-dimensional component formed without using a cooling medium circulation, and ② is a three-dimensional component formed after using a cooling medium circulation.

[0029] Figure 4 This is a schematic diagram showing a comparison of the microstructures of a three-dimensional component according to some embodiments of the present application, wherein ① is an OM microscopic diagram of a three-dimensional component formed without using a cooling medium circulation, ② is an OM microscopic diagram of a three-dimensional component formed with a cooling medium circulation, ③ is an SEM electron microscope image of a three-dimensional component formed without using a cooling medium circulation, and ④ is an SEM electron microscope image of a three-dimensional component formed with a cooling medium circulation.

[0030] Figure 5 It is a comparative schematic diagram of the mechanical properties of an exemplary three-dimensional component according to some embodiments of the present application.

[0031] Figure 6 This is a scanning schematic diagram of an exemplary sliced layered cooling medium circulation powder material additive manufacturing according to some embodiments of the present application.

[0032] Figure 7 Schematic diagram of a scanning diagram of an exemplary powder material additive manufacturing with partitioned cooling medium circulation according to some embodiments of the present application.

[0033] Figure 8 It is a cross-sectional schematic diagram of an exemplary sliced and layered forming base with a variable guide unit according to some embodiments of the present application.

[0034] Figure 9 This is a scanning schematic diagram of an exemplary powder material additive manufacturing with adjacent layer cooling medium circulation according to some embodiments of the present application.

[0035] Figure 10 Schematic diagram of a scanning diagram of an exemplary powder material additive manufacturing with cross-layer cooling medium circulation according to some embodiments of the present application.

[0036] Figure 11 It is a cross-sectional schematic diagram of an exemplary partitioned forming base with a variable guide unit according to some embodiments of the present application.

[0037] Figure 12 This is a scanning schematic diagram of an exemplary powder material additive manufacturing with adjacent zone cooling medium circulation according to some embodiments of the present application.

[0038] Figure 13 This is a scanning schematic diagram of an exemplary powder material additive manufacturing with cross-zone cooling medium circulation according to some embodiments of the present application.

[0039] Figure 14 This is a schematic diagram of a framework of an exemplary electronic device according to some embodiments of the present application.

[0040] Description of the accompanying drawings:

[0041] 1. Optical path unit, 2. Forming base, 3. Electronic device, 4. Three-dimensional component, 20. Cooling medium, 21. Cooling medium control circuit, 21a. Cooling medium control circuit I, 21b. Cooling medium control circuit II, 21c. Cooling medium control circuit III, 21d. Cooling medium control circuit IV, 21e. Cooling medium control circuit V, 22. Cooling circulation channel, 23. Variable guide unit, 200. Cooling area, 200a. Area I, 200b. Area II, 200c. Area III, 200d. Area IV, 200e. Area V, 301. Memory, 302. Processor, 303. Communication interface. DETAILED DESCRIPTION

[0042] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in a variety of forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that this application will be more comprehensive and complete and will fully convey the concepts of the example embodiments to those skilled in the art. The described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to provide a thorough understanding of the embodiments of this application.

[0043] The embodiments of this application are not limited to a specific type of additive manufacturing and can be applied to various powder-based additive manufacturing processes, including laser-directed energy deposition (L-DED), laser powder bed fusion (LPBF), electron beam melting (EBM), selective laser melting (SLM), selective laser sintering (SLS), and other additive manufacturing processes that use powder as the forming material and an energy beam (such as a laser beam, ion beam, or electron beam) as the energy source. The term "powder material" generally refers to the base material for forming three-dimensional components. It is in a granular form and can have different morphologies, particle sizes, and size distributions. In preferred embodiments, metal powder systems are used, including typical engineering materials such as stainless steel, aluminum alloys, titanium alloys, nickel-based alloys, cobalt-based alloys, copper, and copper alloys. Other optional embodiments can also be expanded to ceramic-based, polymer-based, or composite powder systems.

[0044] Currently, the evolution of microstructure in powder material additive manufacturing is affected by multiple factors. Two important factors determine the microstructure: the local solidification conditions in the molten pool and the temperature field in the deposited sample under thermal cycling. These two factors are affected by heat input on the one hand and the ability to store and remove heat on the other. At present, the powder materials used in powder material additive manufacturing are mainly titanium alloys, high-temperature alloys, stainless steel, aluminum alloys and other powder materials. For titanium alloys, the faster the solidification rate, the easier it is to obtain equiaxed crystals or refined grains. For high-temperature alloys, stainless steel, 2 series (Al-Cu) and 7 series (Al-Zn-Mg-Cu) aluminum alloys, due to the epitaxial growth of internal dendrites along the deposition direction during deposition, the dendrite growth direction in local areas will change with the molten pool morphology and scanning strategy. In addition, the liquid phase between the dendrites of the alloy itself is not easy to shrink during solidification, and it is very easy to crack under the action of thermal stress, which greatly affects the forming quality and tensile properties. Moreover, even for Al-Si alloys, which are very easy to form, due to their low gold density, during the powder material additive manufacturing process, the powder material is easily scattered when transferred to the molten pool. At the same time, due to the low melting point of aluminum alloys, it is not easy to solidify in the molten pool. The cladding layer is prone to semi-solid creep during deposition, resulting in defects in the surface morphology and internal quality of the formed three-dimensional components.

[0045] In addition, in the additive manufacturing process of powder materials, the energy beam emitted by the optical path unit 1 is used as a heat source to scan along the planned path. At the same time, the powder material is continuously fed in, melted, formed into a molten pool and then solidified, and stacked layer by layer to finally construct the target component. During the deposition process, a large amount of heat generated by the interaction between the energy beam and the powder material is mainly transferred from the molten pool to the deposited part and the forming base 2 by heat conduction, forming a temperature gradient that decreases from top to bottom. However, in the actual forming process, due to the long heat conduction path and limited heat extraction efficiency, the heat is often not extracted in time, and the temperature of the forming base 2 gradually increases, making the overall heat accumulation phenomenon in the forming area obvious. In this case, the temperature field in the formed part and the molten pool during the forming process is affected, resulting in a decrease in the cooling rate, resulting in a coarse microstructure, and ultimately affecting the tensile mechanical properties of the formed three-dimensional component 4.

[0046] Therefore, reference Figure 1 As shown, Figure 1A schematic structural diagram of an exemplary forming base with a cooling circulation channel in some embodiments of the present application is shown. In some embodiments of the present application, in order to quickly remove heat and reduce heat accumulation in the forming area, the present application relates to a cooling medium 20 circulation device for powder material additive manufacturing. Based on existing additive manufacturing equipment, a cooling circulation channel 22 is set in the forming base 2 and a circulating cooling medium 20 is passed through it. The heat generated during the forming process is promptly removed, and the temperature gradient and cooling rate inside the formed part and the molten pool are increased. This can not only effectively improve the appearance and internal quality of the deposited sample, but also increase the cooling rate inside the molten pool, thereby achieving the purpose of refining the microstructure, and then simultaneously improving the strength and plasticity of the deposited sample.

[0047] Among them, the cooling medium 20 used in the present application can be any form of fluid medium as long as it can quickly extract the heat from the forming base 2, including but not limited to liquid cooling medium 20, gas cooling medium 20 or liquid and solid combined cooling medium 20. The specific setting is made by the designer according to actual needs. For example, the liquid cooling medium 20 can adopt at least one of coolant, cooling oil, cooling water, etc., for example, the gas cooling medium 20 can adopt at least one of nitrogen, argon, helium, etc., for example, the liquid and solid combined cooling medium 20 can adopt at least one of phase change material (such as paraffin) and liquid cooling medium, solid carbon dioxide and liquid cooling medium, etc.

[0048] Therefore, the specific cooling medium 20 circulation device for powder material additive manufacturing includes at least a forming base 2, at least one pulse pump, a temperature monitoring unit and a control unit. The forming base 2 is provided with at least one cooling circulation channel 22, and the at least one pulse pump is connected to the at least one cooling circulation channel 22, and is used to drive the cooling medium 20 to realize a periodic pulse thermal disturbance mode in the cooling circulation channel 22; the temperature monitoring unit is arranged in the forming bin and the forming base 2 of the additive manufacturing equipment, and is used to collect real-time temperature data; the control unit connects and controls at least one pulse pump and the temperature monitoring unit to execute the powder material additive manufacturing method using the cooling medium 20 circulation involved in this application.

[0049] Specifically, when designing the cooling circulation channel 22 opened for the forming base 2, the cooling circulation channel 22 of the forming base 2 is layered and / or partitioned according to the three-dimensional geometric model of the target component and the scanning path, and the entire forming base 2 is divided into cooling areas 200 of different layers and / or cooling areas 200 of different intervals. Each cooling area 200 has an independent cooling circulation channel 22 and a cooling medium control circuit 21. The independent cooling medium control circuit 21 includes at least one pulse pump and a controller.

[0050] The number of the at least one pulse pump is greater than or equal to the number of the cooling medium control loops 21, and the pulse pump can be any form of pump as long as it can realize the pulse circulation of the cooling medium 20 in the cooling circulation channel 22, including but not limited to electromagnetic pulse pumps, piezoelectric pulse pumps, mechanical pulse pumps, peristaltic pumps, etc., and the specific setting is made by the designer according to actual needs.

[0051] The temperature monitoring unit can be any form of temperature monitoring equipment as long as it can obtain the temperature data of the forming area, including but not limited to infrared thermal imagers, multi-channel temperature recorders, temperature sensors distributed in the forming chamber and in each cooling area 200 of the forming base 2, etc., and is specifically set by the designer according to actual needs.

[0052] Therefore, reference Figure 2 As shown, Figure 2 A schematic diagram of a scanning process for powder material additive manufacturing using a cooling medium circulation method according to some embodiments of the present application is shown. When the cooling medium circulation device 20 for powder material additive manufacturing according to the present application is used to perform a powder material additive manufacturing method using a cooling medium circulation method, the specific process is as follows:

[0053] The first step is to design the forming base 2. In the additive manufacturing process, an alloy material with the same or similar composition as the powder material is usually selected as the forming base 2. Then, the geometric model of the target component is sliced and / or partitioned to obtain at least one cooling area 200 including at least a portion of the target component and an independent cooling medium control loop 21 is set for each cooling area 200. Then, according to the above design requirements, a number of regular channels are opened on the forming base 2 as cooling circulation channels 22 for the flow of cooling medium 20. Then, the inlet and outlet of each cooling circulation channel 22 are respectively connected to the catheter. The outer surface of the catheter is wrapped with tin foil to prevent the heat from the deposition process from burning the catheter. The other end of the catheter is connected to at least one pulse pump of the corresponding cooling medium control loop 21. Figure 1 As shown, for example: a ZL104 aluminum alloy forming base 2 with a size of 200 mm × 200 mm × 20 mm (height) is selected, a 30 mm spacing is left on both sides of the long side, and 8 equally spaced holes with a diameter of 8 mm are dug out as cooling circulation channels 22 for the flow of cooling medium 20. The cooling circulation channels 22 are connected by a conduit, the outer surface of the conduit is wrapped with tin foil, and the conduit is fastened to the forming base 2 by screw threads.

[0054] The second step is to place the punched forming base 2 in the forming chamber of the additive manufacturing equipment for matching installation. It is secured with a clamping device and the conduit is connected to the fluid medium pulse pump. The fluid medium pulse pump is turned on to fill the cooling circulation channel 22 with circulating fluid. After the cooling circulation channel 22 is inspected for leaks, the fluid medium pulse pump is turned off. To prevent the conduit from being burned by high temperatures, a 500 mm x 500 mm square iron plate can be placed in the forming area of the forming base 2. This will transfer the heat generated by the forming of the three-dimensional component 4 through the iron plate.

[0055] The third step is powder material preparation. Before AM, the powder material is dried in a powder oven, typically at 120°C for 3 hours. For energy beam AM, the powder material particles are typically screened to a size range of 40μm-170μm.

[0056] In the fourth step, after the forming base 2 is installed and fixed, the forming chamber is sealed with a glass cover and a plastic film, and the forming chamber is filled with an inert gas (argon / helium). When the oxygen content in the chamber drops below 100 ppm, additive manufacturing processing can be carried out.

[0057] In the fifth step, the dried AlSi10Mg alloy powder material with a particle size of 47μm~165μm is placed into the powder bin, the synchronous powder feeding device is turned on, and the powder feeding passage is inspected.

[0058] The sixth step is the additive manufacturing forming preparation process. The pulse pump of the fluid medium is turned on to fill the cooling circulation channel 22 with the cooling medium 20. When all equipment such as the forming base 2, the powder feeding device of the additive manufacturing equipment, and the optical path unit 1 are in a stable and reliable state, energy beam additive manufacturing is performed according to the scanning strategy in the program. Before additive manufacturing, the scanning program is compiled, the energy beam path is checked, and the forming parameters are set. For different alloy systems, the specific parameters used are different, but the parameter range is usually: energy beam power 100 W-3000 W; scanning rate 5 mm / s-100 mm / s; energy beam diameter 1 mm-5 mm; overlap rate 30%-80%; lifting amount 0.05 mm-2 mm; scanning strategy is forward / reverse reciprocating scanning; powder feeding amount 1 g / min-10 g / min; gas flow rate 1 L / min-20 L / min.

[0059] For example, the process parameters used for aluminum alloy powder material are as follows:

[0060] Table 1: Directed energy deposition forming process parameters for aluminum alloy powder materials

[0061]

[0062] The seventh step is to carry out additive manufacturing of aluminum alloy powder materials. During manufacturing, a preset periodic pulse thermal disturbance mode with a cooling medium 20 flushing frequency and flow rate is allocated to the at least one cooling area 200 according to the at least one cooling area 200 and combined with the real-time temperature distribution and / or process goals, and then the periodic pulse thermal disturbance mode is applied to the energy beam scanning process, so that when the energy beam scans the cooling area 200 on the forming base, its corresponding cooling medium control loop 21 is switched to a matching periodic pulse thermal disturbance mode, and the cooling medium 20 with the corresponding periodic pulse thermal disturbance mode is provided to each cooling area 200 of the forming base 2 in real time.

[0063] In the eighth step, additive manufacturing is completed. After the target component is printed, the powder feeding device and the optical path unit 1 are turned off. At the same time, the cooling medium 20 and the inert gas still need to be running. After the temperature of the forming base 2 drops to room temperature, the pulse pump of the fluid medium and the inert gas valve are turned off, the forming chamber is opened and the forming chamber and the forming base 2 are cleaned, the clamping device is removed, the forming base 2 and the target component are removed, and the target component is cut off from the forming base 2 using an electric spark wire cutting machine. Inside the target component, the electric spark wire cutting machine is used to cut off the sample for metallographic structure observation and mechanical tensile test.

[0064] In the ninth step, the sample surface was metallographically treated using sandpaper, polishing liquid, etching liquid, etc. for optical microscopy (OM) and scanning electron microscopy (SEM) microstructure observation, and then a universal mechanical specimen machine was used to conduct a quasi-static axial tensile test at room temperature.

[0065] refer to Figures 3 to 5 As shown, Figure 3 A schematic diagram showing a comparison of the apparent quality of an exemplary three-dimensional component according to some embodiments of the present application is shown. Figure 3 ① is a three-dimensional component 4 formed without circulating the cooling medium 20. Figure 3 ② is a three-dimensional component 4 formed by circulating the cooling medium 20; Figure 4 FIG2 shows a schematic diagram comparing the microstructure of an exemplary three-dimensional component according to some embodiments of the present application. Figure 4 ① is an OM microscopic diagram of a three-dimensional component 4 formed without using a cooling medium 20 cycle. Figure 4 ② is an OM microscopic diagram of a three-dimensional component 4 formed by circulating a cooling medium 20. Figure 4 ③ is the SEM electron microscope image of the three-dimensional component 4 formed without using the cooling medium 20 cycle, Figure 4 ④ is a SEM electron microscope image of the three-dimensional component 4 formed by circulating the cooling medium 20; Figure 5A schematic diagram comparing the mechanical properties of an exemplary three-dimensional component according to some embodiments of the present application is shown. By adopting the above-described technical solution and circulating a cooling medium 20 through the forming base 2, the accumulated heat generated by energy beam melting in the forming area and its adjacent areas can be continuously and effectively removed during the forming process, significantly reducing the impact of heat input on localized overheating of the molten pool. This significantly refines the microstructure of the formed three-dimensional component 4, improves its surface and internal quality, and enhances its tensile mechanical properties.

[0066] In some examples of the present application, when allocating a preset periodic pulse thermal disturbance pattern with a cooling medium flushing frequency and flow rate, the temperature distribution of the cooling area 200 is reconstructed using a two-dimensional instantaneous heat conduction equation based on the collected real-time temperature distribution data; a periodic heat flux model coupled with the molten pool boundary is established based on the characteristics of the generated pulse cooling medium 20; based on the periodic heat flux model, a grain growth disturbance model of grain refinement rate, temperature disturbance and gradient is established; a preset optimization function is constructed, and the pulse parameters are updated in real time to maximize the grain refinement rate within a limited time and / or space range; thus, a periodic pulse thermal disturbance pattern with corresponding pulse parameters is allocated to each cooling area 200 in combination with the real-time temperature distribution and / or process objectives to control the cooling medium control loop 21 of the cooling area 200 to execute the corresponding working mode.

[0067] Among them, the pulse parameters include the flushing frequency and flow rate of the cooling medium 20. The flushing frequency of the cooling medium 20 is adjustable from 0.1 to 10 Hz, the pulse pressure is adjustable from 0 to 1.5 MPa, and the pulse flow rate is adjustable from 100 to 6000 mL / min. The pulse waveform includes at least one of a trapezoidal wave, a sine wave, a square wave, and a convex wave. The set temperature range of the cooling medium 20 is -40°C to 160°C; and each cooling area 200 can adopt the same periodic pulse thermal disturbance mode of the flushing frequency and flow rate of the cooling medium 20, or can adopt a periodic pulse thermal disturbance mode of different flushing frequencies and flow rates of the cooling medium 20, which is specifically set by the designer according to actual needs.

[0068] Therefore, when reconstructing the temperature distribution of the cooling area 200 using the two-dimensional transient heat conduction equation based on the collected real-time temperature distribution data, it is assumed that the geometric model is a two-dimensional plane (x, y) after analysis, the heating source is a scanning energy beam, which is represented by a time-to-space distribution heat source, and the cooling is the boundary cooling flux caused by time variation (which is caused by the pulsed cooling medium 20); the specific method includes:

[0069] According to the temperature distribution data collected by the temperature monitoring unit, the two-dimensional plane temperature field T(x, y, t) is obtained at each time t and the two-dimensional transient heat conduction equation is defined: , where ρ is the material density, is the time derivative of the temperature field, is the second-order derivative of temperature with respect to spatial position x, is the second-order derivative of temperature with respect to spatial position y, c p is the specific heat capacity of the material, T(x,y,t) is the temperature field at spatial position x,y at time t, k is the thermal conductivity of the material, and Q(x,y,t) is the heat source term of the energy beam input, that is, the heating heat flux density of the energy beam at spatial position x,y at time t.

[0070] Use a two-dimensional Gaussian distribution heat source to simulate the scanning energy beam input heat source term:

[0071] , where η is the energy beam absorptivity, P is the energy beam power, r is the energy beam radius, and (x0(t), y0(t)) are the scanning center coordinates of the heat source position that changes with time.

[0072] Define the cooling boundary conditions for applying the pulse cooling medium 20. The cooling boundary conditions are used to affect the overall temperature field change and reflect the influence of thermal disturbance. Assume that the molten pool cooling surface between the forming base 2 and the three-dimensional component 4 is y = 0, and apply the pulse cooling boundary heat flux on this surface:

[0073] , where h(t) is the pulse heat transfer coefficient, which is controlled by the pulse of the cooling medium 20: , h0 is the cooling base heat transfer coefficient, A is the pulse disturbance flow rate coefficient, f is the pulse flushing frequency, T cool is the temperature of the cooling medium 20.

[0074] The two-dimensional forming area is discretized into a grid and the spatial step Δx, Δy and the time step Δt are set. Then, the initial temperature is assigned and the initial two-dimensional plane temperature field T(x, y, t) is set to room temperature.

[0075] Calculate the energy beam heat source position .

[0076] Update cooling boundary conditions .

[0077] The internal node temperature values are updated using the explicit finite difference method. The formula of the explicit finite difference method is:

[0078] ,in,

[0079] , , where α x +α y ≤1 / 2, is the temperature at position (i, j) at time n, is the heat source at position (i, j) at time n, αx is the thermal diffusivity in the x direction, α y is the thermal diffusion coefficient in the y direction, Δx is the spacing of the grid units in the x direction, and Δy is the spacing of the grid units in the y direction.

[0080] Output the two-dimensional plane temperature field T(x,y,t) at each time step.

[0081] When establishing a periodic heat flux model, a pulse pump provides a periodically variable speed cooling medium 20, whose cooling intensity is non-constant. The cooling medium 20 is transferred to the base of the molten pool through the cooling circulation channel 22. The pulsed cooling medium 20 causes the heat transfer coefficient h(t) to fluctuate periodically. The cooling behavior directly determines the thermal disturbance characteristics of the solidification boundary of the molten pool. The specific method includes:

[0082] Apply a time-varying heat transfer boundary to the cooling surface of the melt pool: , where q cool (t) is the instantaneous cooling heat flux per unit area, T s (t) is the instantaneous temperature of the cooling surface of the molten pool.

[0083] The Reynolds number and the convection heat transfer coefficient equation are calculated according to the real-time cooling medium 20 flow rate change to reconstruct the instantaneous heat transfer coefficient of the cooling medium 20: , where N u (t) is the Nusselt number, N u (t)=0.23*R e (t) 0.8 *P r (t) 0.4 ,

[0084] is the Reynolds number, which reflects the ratio of fluid inertia force to viscous force; is the Prandtl number, reflecting the ratio of thermal diffusion to momentum diffusion; D h is the medium diameter of the cooling circulation channel 22, v(t) is the flow rate of the cooling medium 20; ρ f is the density of the cooling medium 20, μ is the dynamic viscosity of the cooling medium 20, c p,f is the specific heat capacity of the cooling medium 20, k f is the thermal conductivity of the cooling medium 20.

[0085] The cooling heat flux at each moment is calculated based on the instantaneous heat transfer coefficient and the temperature of the cooling medium 20 .

[0086] The cooling heat flux at each moment is applied as a Neumann boundary to the two-dimensional transient heat conduction equation to update the temperature value using the explicit finite difference method; where, for the cooling boundary y=0,

[0087] , the equivalent form can be approximated by difference as follows:

[0088] , and the boundary node temperature update formula is obtained as follows:

[0089] .

[0090] The thermal gradient fluctuation caused by periodic cooling thermal disturbance can be quantified as: , which determines the cooling rate of the solidification interface .

[0091] Therefore, when establishing a grain growth disturbance model, thermal disturbances produce non-steady-state temperature fluctuations and stimulate grain fragmentation or redirection. The temperature gradient and cooling rate jointly determine the grain growth direction. Therefore, the grain refinement rate can be used as an indicator to characterize microstructure uniformity. Specific methods include:

[0092] Establish the refinement differential equation of the refinement rate growth rate: , where G(t) is the temperature gradient, η(t) is the grain refinement rate, representing the proportion of the refined area; α is a material constant; m and n are empirical exponents, for example, m=1, n=1 indicates a linear effect; and [1-η(t)] can be expressed as the proportion of the unrefined area. Furthermore, when considering periodic thermal disturbances, the grain refinement rate is also affected by the flushing frequency and flow rate, so a disturbance enhancement function is introduced:

[0093] , thus, after coupling the disturbance enhancement function into the refined differential equation, it becomes:

[0094] .

[0095] Then, the output temperature value is obtained from the heat conduction equation and the cooling rate R(t) and temperature gradient are calculated:

[0096] , The gradient of the temperature field;

[0097] The disturbance enhancement function is calculated based on the flushing frequency and flow rate of the cooling medium 20. When the cooling medium 20 has a spatial flow rate gradient or the pulse pump is multi-point pulse controlled, the disturbance enhancement function can be expanded to:

[0098] , where A(x,y) is the local flow velocity and f(x,y) is the local flushing frequency, thereby reflecting that different cooling areas 200 are affected by different thermal disturbances, and further improving the local control capability of the growth of the equiaxed crystal area.

[0099] Solving the refinement differential equation to generate the grain refinement ratio ; where the grain refinement ratio of each mesh is updated using an explicit finite difference method in parallel with the calculation of the internal node temperature values:

[0100] , is the value of the impulse perturbation enhancement function at n, The cooling rate at position (i, j) when n is, The temperature gradient at position (i, j) when n is given.

[0101] Output equiaxed crystal ratio field: and grain refinement rate.

[0102] Therefore, when the pulse parameters are updated in real time, the flushing frequency and flow rate of the cooling medium 20 output by the pulse pump are dynamically adjusted by constructing a feedback control optimization function, so that the grain refinement rate is maximized within a limited time or space range, thereby adjusting the grain refinement effect to the optimal level and suppressing the growth of columnar grains. The specific method includes:

[0103] Construct a preset optimization function based on the grain refinement model: , that is, maximizing the integral of the grain refinement rate per unit time; where J(f,A) is the constructed optimization objective function to accumulate the grain refinement rate.

[0104] The preset optimization strategy is used to search for the optimal cooling medium 20 flushing frequency and flow rate to update the cooling medium 20 flushing frequency and flow rate; wherein, the preset optimization strategy includes but is not limited to existing optimization strategies such as gradient ascent, genetic algorithm, and reinforcement learning; for example, referring to the use of gradient ascent, the partial derivative can be obtained , the update strategy is:

[0105] , where γ is the step size.

[0106] The updated flushing frequency and flow rate of the cooling medium 20 are output as control signals to the corresponding cooling medium control circuit 21 .

[0107] Therefore, the above-mentioned periodic pulse thermal disturbance control process is: obtain and reconstruct the temperature distribution of the cooling area 200 at the energy beam scanning position and calculate the corresponding cooling rate, temperature gradient and grain refinement rate, and then update the corresponding optimization objective function and generate the optimized cooling medium 20 flushing frequency and flow rate, and control the corresponding cooling medium control loop 21 to execute the optimized cooling medium 20 flushing frequency and flow rate, so as to extract the heat accumulated in the cooling area 200 and improve the appearance and internal quality of the target component of the part belonging to the area.

[0108] In some examples of this application, when constructing a preset optimization function, an improved objective function may be constructed:

[0109] , where λ1 and λ2 are penalty coefficients for adjusting flushing frequency and flow rate to achieve a compromise between grain refinement efficiency and energy consumption limit.

[0110] In some examples of this application, dynamic constraints can be set to prevent device damage or material quality degradation when optimizing pulse parameters: and , where f min is the minimum flushing frequency, f opt is the optimized flushing frequency, f max is the maximum flushing frequency, where A min is the minimum flow rate, A opt is the optimized flow rate, A max is the maximum flow rate.

[0111] By adopting the above technical solution, a large number of micro-area equiaxed crystals are induced to form in the three-dimensional component 4 through the periodic thermal disturbance mechanism, breaking the continuous growth path of the columnar crystals, and improving the microstructure refinement ability by coupling the disturbance of the molten pool boundary layer with the heat flux distribution, thereby improving the microstructure homogenization and densification enhancement effect.

[0112] In some embodiments of the present application, when the geometric model of the target component is sliced and analyzed, the geometric model of the target component is layered and analyzed, thereby obtaining at least one cooling area 200 including at least one layer of the target component based on the layered data of the target component after slicing, and setting an independent cooling medium control loop 21 for each layer of cooling area 200, that is, a single-layer cooling area 200 can be allocated to a single-layer target component, or multiple layers of cooling areas 200 can be allocated to a single-layer target component, or a single-layer cooling area 200 can be allocated to a multiple-layer target component, or multiple layers of cooling areas 200 can be allocated to a multiple-layer target component. Therefore, after the slicing analysis, the designer designs a single-layer or multi-layer stacked cooling circulation channel 22 for the forming base 2 according to actual needs and the above-mentioned cooling area 200 division process.

[0113] Therefore, the powder material additive manufacturing method using the cooling medium 20 circulation mentioned above further includes:

[0114] A slice analysis is performed on the geometric model of the target component to obtain at least one cooling area 200 including at least one layer of the target component and an independent cooling medium control loop 21 is set for each cooling area 200; a preset periodic pulse thermal disturbance pattern with a flushing frequency and flow rate of the cooling medium 20 is allocated to the at least one cooling area 200 according to the at least one cooling area 200 and in combination with the real-time temperature distribution and / or process target; the periodic pulse thermal disturbance pattern is applied to the energy beam scanning process, so that when the energy beam scans on the forming base, the cooling medium control loop 21 of the corresponding layer of the target component is switched to a matching periodic pulse thermal disturbance pattern.

[0115] refer to Figure 6 As shown, Figure 6 A scanning schematic diagram of an exemplary sliced layered cooling medium circulation powder material additive manufacturing of some embodiments of the present application is shown. For example, when performing slice analysis on the geometric model of the target component, four layers of cooling circulation channels 22 and their corresponding cooling medium control loops 21 are allocated to the layered target component, and the four layers of cooling circulation channels 22 and their corresponding cooling medium control loops 21 are matched with the layered data of the target component, corresponding to four groups of layer families of the target component, each group of layer families can be single-layer or multi-layer slices, thus being divided into layer family I, layer family II, layer family III and layer family IV, as well as cooling medium control loop I21a matching layer family I, cooling medium control loop II21b matching layer family II, cooling medium control loop III21c matching layer family III and cooling medium control loop IV21d matching layer family IV.

[0116] When the energy beam scans the laying powder material on the forming base to form the forming layer family I, the optimized flushing frequency and flow rate of the cooling medium 20 are generated according to the above-mentioned periodic pulse thermal disturbance control process, and then a periodic pulse thermal disturbance pattern matching the cooling medium control loop I21a is generated according to the optimized pulse parameters, and then the cooling medium control loop I21a is controlled to execute the corresponding periodic pulse thermal disturbance pattern; and so on, until the forming of the target component is completed.

[0117] In some embodiments of the present application, when performing a partition analysis on the geometric model of the target component, the geometric model of the target component is partitioned and analyzed, thereby obtaining at least one cooling area 200 including at least a portion of the target component based on the partition data of the target component after slicing, and setting an independent cooling medium control loop 21 for each cooling area 200, that is, a single cooling area 200 can be allocated to part of the target components, or a plurality of cooling areas 200 can be allocated to part of the target components. Therefore, after the partition analysis, the designer designs a single-zone or multi-zone superimposed cooling circulation channel 22 for the forming base 2 according to actual needs and the above-mentioned cooling area 200 division process.

[0118] Therefore, the powder material additive manufacturing method using the cooling medium 20 circulation mentioned above further includes:

[0119] A partition analysis is performed on the geometric model of the target component to obtain at least one cooling area 200 including at least a portion of the target component and an independent cooling medium control loop 21 is set for each cooling area 200; a preset periodic pulse thermal disturbance pattern with a flushing frequency and flow rate of the cooling medium 20 is assigned to at least one cooling area 200 according to the at least one cooling area 200 and in combination with the real-time temperature distribution and / or process target; the periodic pulse thermal disturbance pattern is applied to the energy beam scanning process, so that when the energy beam is scanned on the forming base, the cooling medium control loop 21 corresponding to the cooling area 200 where the energy beam is located is switched to a matching periodic pulse thermal disturbance pattern.

[0120] refer to Figure 7 As shown, a scanning schematic diagram of a powder material additive manufacturing with an exemplary partitioned cooling medium circulation in some embodiments of the present application is shown. For example, when performing a partition analysis on the geometric model of the target component, the cooling circulation channels 22 and their corresponding cooling medium control loops 21 in five regions are allocated to the partitioned target component, and the cooling circulation channels 22 and their corresponding cooling medium control loops 21 in the five regions are matched with the partition data of the target component, respectively corresponding to the five regions of the target component, thereby being divided into region I 200a, region II 200b, region III 200c, region IV 200d and region V 200e, as well as a cooling medium control loop I 21a matching region I, a cooling medium control loop II 21b matching region II, a cooling medium control loop III 21c matching region III, a cooling medium control loop IV 21d matching region IV and a cooling medium control loop V 21e matching region V.

[0121] When the energy beam scans the forming area I200a of the laid powder material on the forming base, the optimized flushing frequency and flow rate of the cooling medium 20 are generated according to the above-mentioned periodic pulse thermal disturbance control process, and then a periodic pulse thermal disturbance pattern matching the cooling medium control loop I21a is generated according to the optimized pulse parameters, and then the cooling medium control loop I21a is controlled to execute the corresponding periodic pulse thermal disturbance pattern; and so on, until the forming of the target component is completed.

[0122] In some embodiments of the present application, the periodic pulse thermal disturbance pattern includes a transitional thermal disturbance pattern between at least two cooling regions 200 .

[0123] Specifically, when the energy beam scans across the boundary between two regions, a transitional thermal disturbance zone is formed. To prevent cracks or structural discontinuities caused by sudden temperature gradient changes, a step-by-step cooling intensity is introduced into this transitional zone. This is achieved by adjusting the pulse parameters (e.g., the pulse parameters transition from Q1 in the first region to Q2 in the second region) to form a continuously changing thermal disturbance waveform. Specifically: , where x is the energy beam scanning position, x0 is the starting point of the transition zone, and L is the length of the transition zone; thus, by adjusting the difference between L and Q1 and Q2, transition disturbances with different flushing frequencies and flow rates can be obtained, which is conducive to the formation of a uniform and refined grain structure.

[0124] In some embodiments of the present application, the periodic pulse thermal disturbance pattern includes a composite thermal disturbance pattern formed by stacking at least two cooling regions 200 .

[0125] Specifically, multiple cooling zones 200 (such as the first zone, the second zone, and the third zone) are arranged in a spatial stacking manner, so that the energy beam molten pool passes through multiple zones with different pulse parameters along a periodic path during the processing process, thereby generating a multi-parameter coupled thermal disturbance response. The stacking can be spatial overlap (such as the superposition of multi-layer microchannel structures) or temporal stacking (such as the energy beam repeatedly entering different cooling zones during scanning), forming a composite superposition of thermal disturbances, which has a composite effect on the heat accumulation and grain evolution of the molten pool. For example, the flushing frequency of the cooling medium 20 in the first zone is f1, and the flushing frequency of the cooling medium 20 in the second zone is f2. After superposition, the main disturbance frequency f = f1 + f2 is formed, and the pulse pattern is constructed with the assistance of the periodicity of the energy beam scanning: , where A1 and A2 are the flow velocity parameters of the first area and the second area respectively.

[0126] The periodic pulse thermal disturbance mode constructed by adopting the above technical solution can effectively promote grain refinement, improve organizational uniformity, and improve thermal cracks and internal defects commonly seen in the additive manufacturing process of powder materials.

[0127] refer to Figure 8 and Figure 11 As shown, Figure 8 shows a cross-sectional schematic diagram of an exemplary sliced and layered forming base with a variable guide unit according to some embodiments of the present application, Figure 11 A schematic cross-sectional view of an exemplary partitioned forming base with variable flow guide units according to some embodiments of the present application is shown. In some embodiments of the present application, the cooling medium 20 circulation device for powder material additive manufacturing of the present application also includes a variable flow guide unit 23, which is disposed within the plurality of cooling circulation channels 22 to achieve dynamic changes in the direction of the cooling medium 20.

[0128] Specifically, the variable guide unit 23 can be any form of structure as long as it can realize dynamic changes in the direction of the cooling medium 20, including but not limited to at least one of a valve, an adjustable nozzle, a diverter or a multi-channel switching device driven by an actuator; the number of variable guide units 23 matches the number of cooling circulation channels 22, and the various cooling circulation channels 22 can be connected through the variable guide unit 23, allowing the cooling medium 20 to circulate in several connected cooling circulation channels 22, further realizing real-time regulation of cooling boundary thermal disturbances and grain growth behavior, thereby inducing multi-directional equiaxed grain growth of the organization and inhibiting the expansion of thermal cracks along a specific path.

[0129] refer to Figure 9 and Figure 10 As shown, Figure 9 A scanning schematic diagram of an exemplary powder material additive manufacturing with adjacent layer cooling medium circulation according to some embodiments of the present application is shown. Figure 10 A scanning schematic diagram of a powder material additive manufacturing with cross-layer cooling medium circulation according to some embodiments of the present application is shown. When performing slicing analysis, the geometric model of the target component is layered and analyzed, thereby obtaining at least one cooling area 200 including at least one layer of the target component based on the layered data of the target component after slicing, and setting an independent cooling medium control circuit 21 for each layer of cooling area 200, and then, according to demand, the cooling medium control circuit 21 of the adjacent layer or the collapsed layer can be connected through the variable guide unit 23, so that the cooling medium 20 can circulate in the cooling medium control circuit 21 of the adjacent layer or the collapsed layer through the variable guide unit 23, and the adjacent layers can be two adjacent layers, or three or more adjacent layers; the collapsed layers can be separated by one layer, or two or more layers, and the specific setting is made by the designer according to actual needs.

[0130] refer to Figure 12 and Figure 13 As shown, Figure 12 A scanning schematic diagram of an exemplary powder material additive manufacturing with adjacent zone cooling medium circulation according to some embodiments of the present application is shown. Figure 13A scanning schematic diagram of powder material additive manufacturing with cross-zone cooling medium circulation according to some embodiments of the present application is shown. When performing partition analysis, the geometric model of the target component is partitioned and analyzed, thereby obtaining at least one cooling area 200 including at least a portion of the target component based on the partition data of the target component after slicing, and setting an independent cooling medium control circuit 21 for each cooling area 200, and then, according to needs, the cooling medium control circuits 21 of adjacent areas or cross-areas can be connected through a variable guide unit 23, so that the cooling medium 20 can circulate in the cooling medium control circuits 21 of adjacent areas or cross-areas through the variable guide unit 23. The adjacent areas can be two adjacent areas, or three or more adjacent areas; the cross-areas can be separated by one area, or two or more areas, which are specifically set by the designer according to actual needs.

[0131] In some embodiments of the present application, based on any one or more of the above embodiments, the temperature of the cooling medium 20 can also be set to be adjustable. When a periodic pulse thermal disturbance mode is set for the cooling area 200, the temperature parameters of the cooling medium 20 are introduced into the pulse parameters to more accurately adjust the temperature of the forming base 2.

[0132] Specifically, after introducing the temperature parameter of the cooling medium 20, define , where T0 is the average cooling medium 20 temperature, B is the temperature disturbance value, f T is the temperature disturbance frequency, is the phase difference between temperature disturbance and flow velocity disturbance, which is used to control peak superposition and staggered cooling behavior. After introducing the temperature disturbance control factor, the enhancement function can be further expanded to:

[0133] ,

[0134] Where β is the response factor of temperature perturbation to grain growth perturbation; thus, the optimization objective function is expanded to:

[0135] , where λ1, λ2 and λ3 are weight coefficients for adjusting the flushing frequency, flow rate and temperature of the cooling medium 20.

[0136] Therefore, if the gradient ascent optimization strategy is adopted, the exemplary one is:

[0137] , ,

[0138] , where γ1, γ2, γ3, γ4, and γ5 are step sizes.

[0139] By adopting the above technical solution and setting the temperature of the adjustable cooling medium 20, not only the cooling intensity can be controlled, but also the direction and size of the local temperature gradient can be regulated, thereby affecting the grain orientation and refinement trend, and realizing multi-dimensional disturbance control closed-loop optimization.

[0140] In some embodiments, reference Figure 14 As shown, Figure 14 The following is a schematic diagram illustrating the framework of an exemplary electronic device according to some embodiments of the present application. The electronic device 3 includes a memory 301 and a processor 302. The memory 301 stores a computer program executable on the processor 302. When the processor 302 executes the computer program, the method described in the above embodiments is implemented. The number of the memory 301 and the processor 302 may be one or more.

[0141] The electronic device 3 further includes a communication interface 303 for communicating with external devices and performing data exchange transmission.

[0142] If the memory 301, processor 302, and communication interface 303 are implemented independently, the memory 301, processor 302, and communication interface 303 can be connected to each other via a bus and communicate with each other. The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, or an Extended Industry Standard Architecture (EISA) bus. The bus can be divided into an address bus, a data bus, a control bus, etc. For ease of representation, Figure 14 Only one thick line is used in the diagram, but this does not mean that there is only one bus or one type of bus.

[0143] Optionally, in a specific implementation, if the memory 301, the processor 302 and the communication interface 303 are integrated on a chip, the memory 301, the processor 302 and the communication interface 303 can communicate with each other through an internal interface.

[0144] An embodiment of the present application provides a computer-readable storage medium storing a computer program, which implements the method provided in the embodiment of the present application when the program is executed by the processor 302.

[0145] An embodiment of the present application also provides a chip, which includes a processor 302 for calling and executing instructions stored in the memory 301 from the memory 301, so that a communication device equipped with the chip executes the method provided in the embodiment of the present application.

[0146] An embodiment of the present application also provides a chip, including: an input interface, an output interface, a processor 302 and a memory 301. The input interface, the output interface, the processor 302 and the memory 301 are connected through an internal connection path. The processor 302 is used to execute the code in the memory 301. When the code is executed, the processor 302 is used to execute the method provided in the embodiment of the application.

[0147] It should be understood that the processor 302 may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA), or other programmable logic devices, discrete gate or die logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor. It is worth noting that the processor 302 may be a processor 302 that supports the Advanced RISC Machines (ARM) architecture.

[0148] Furthermore, the memory 301 may include a read-only memory and a random access memory, and may also include a non-volatile random access memory. The memory may be a volatile memory or a non-volatile memory, or may include both volatile and non-volatile memories. Among them, the non-volatile memory may include a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), or a flash memory. The volatile memory may include a random access memory (RAM), which is used as an external cache. By way of example but not limitation, many forms of RAM are available. For example, static random access memory (SRAM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), double data rate synchronous dynamic random access memory (DDR SDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchronous link dynamic random access memory (SLDRAM) and direct RAM bus random access memory (DR RAM).

[0149] In the above embodiments, all or part of the embodiments may be implemented using software, hardware, firmware, or any combination thereof. When implemented using software, all or part of the embodiments may be implemented in the form of a computer program product. A computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the processes or functions according to the present application are generated in whole or in part. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions may be stored in a computer-readable storage medium or transferred from one computer-readable storage medium to another.

[0150] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A powder material additive manufacturing method using cooling medium circulation, characterized in that: The method comprises: Slicing and / or partitioning the geometric model of the target component to divide the target component into cooling areas of different layers and / or cooling areas of different intervals, and setting an independent cooling medium control loop for each cooling area; Assigning a preset periodic pulse thermal disturbance pattern with cooling medium flushing frequency and flow rate to each cooling zone based on the cooling zone and in combination with real-time temperature distribution and / or process goals; Applying the periodic pulse thermal disturbance mode to the energy beam scanning process, so that when the energy beam scans the cooling area on the forming base, its corresponding cooling medium control loop is switched to the matching periodic pulse thermal disturbance mode; Wherein, when allocating a preset periodic pulse thermal disturbance mode with a cooling medium flushing frequency and flow rate, the method includes: Based on the collected real-time temperature distribution data, the temperature distribution of the cooling area is reconstructed using the two-dimensional transient heat conduction equation; According to the characteristics of the generated pulse cooling medium, a periodic heat flux model coupled with the molten pool boundary is established; According to the periodic heat flux model, a grain growth perturbation model of grain refinement rate, temperature perturbation and gradient is established; Construct a preset optimization function and update the pulse parameters in real time to maximize the grain refinement rate within a limited time and / or space range; Through the periodic thermal disturbance mode, the formation of equiaxed crystals in the micro-area of the target component is induced, the continuous growth path of the columnar crystal is broken, and the microstructure refinement ability is improved by coupling the disturbance of the molten pool boundary layer with the heat flux distribution, thereby improving the microstructure homogenization and densification enhancement effect.

2. The method according to claim 1, characterized in that When slicing the geometric model of the target component, the method includes: According to the layered data of the target component after slicing, cooling areas including different layers of the target component are obtained and an independent cooling medium control loop is set for each layer of the cooling area.

3. The method according to claim 2, characterized in that During energy beam scanning, the method includes: According to the number of target component layers scanned by the energy beam, the cooling medium control loop corresponding to the cooling area of the target component layers is switched to a matching periodic pulse thermal disturbance mode.

4. The method according to claim 1 or 3, characterized in that The periodic pulse thermal disturbance pattern includes a transitional thermal disturbance pattern between at least two cooling regions or a composite thermal disturbance pattern formed by stacking at least two cooling regions.

5. The method according to claim 1, wherein When reconstructing the temperature distribution of the cooling area, the method includes: Define the two-dimensional transient heat conduction equation and use a two-dimensional Gaussian distribution heat source to simulate the energy beam input; Define cooling boundary conditions for applying pulsed cooling medium; Discretize the two-dimensional region into a grid and set the space and time steps to assign the initial temperature. Calculate the energy beam heat source position; Update cooling boundary conditions; Update the temperature value using the explicit finite difference method; Output temperature distribution.

6. The method according to claim 5, characterized in that When establishing a periodic heat flux model, the method includes: Apply time-varying heat transfer boundaries to the cooling surface of the molten pool; Calculate the Reynolds number and convection heat transfer coefficient equation according to the change of cooling medium flow rate to generate the instantaneous heat transfer coefficient of the cooling medium; Calculate the cooling heat flux at each moment based on the instantaneous heat transfer coefficient and the cooling medium temperature; The cooling heat flux at each time instant is applied as a Neumann boundary to the heat conduction equation to update the temperature value using an explicit finite difference method.

7. The method according to claim 6, characterized in that When establishing the grain growth disturbance model, the method includes: The refinement differential equation of the refinement rate growth rate is established and the disturbance enhancement function is introduced; Get temperature distribution; Calculate cooling rates and temperature gradients; Calculate the disturbance enhancement function based on the flushing frequency and flow rate of the cooling medium; Solve the refinement differential equation to generate the grain refinement ratio; Output equiaxed crystal ratio field.

8. The method according to claim 7, characterized in that When updating the pulse parameters in real time, the method includes: Constructing preset optimization functions based on the grain refinement model; Use the preset optimization strategy to search for the optimal cooling medium flushing frequency and flow rate to update the pulse parameters; The updated pulse parameters are output as control signals to the corresponding cooling medium control loop.

9. The method according to claim 1 or 8, characterized in that The cooling medium control circuit includes a cooling medium pulse parameter control circuit and a cooling medium flow direction control circuit.

10. An electronic device, characterized in that: include: at least one processor; at least one memory; The at least one memory is coupled to the at least one processor and is configured to store instructions to be executed by the at least one processor, wherein the instructions, when executed by the at least one processor, cause the electronic device to perform the method according to any one of claims 1 to 9.

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