Manufacturing equipment and manufacturing method of micro-channel heat exchanger core

Abstract

The invention relates to manufacturing equipment and a manufacturing method of a micro-channel heat exchanger core, and belongs to the technical field of micro-channel heat exchangers. The manufacturing method comprises the steps that a plurality of runners are formed in the surfaces of core plates, the core plates are stacked to form a core body, the core body is placed in diffusion welding equipment, pre-tightening pressure is applied to the core body, and a furnace body of the diffusion welding equipment is vacuumized; the furnace body is vacuumized, heated and subjected to heat preservation, meanwhile, inert gas is introduced into all the flow channels of the core body, and the temperature of the inert gas is gradually increased; after the temperature rises to a preset temperature, inert gas in the furnace body is pumped out, a radiation heating method is adopted for continuous heating, welding pressure is applied to the core body, and welding is completed; and inert gas is introduced into the furnace body for cooling, and meanwhile inert gas is introduced into each flow channel of the core body for step-by-step cooling. Therefore, the heating and cooling time of the heat exchanger core body can be shortened, the welding efficiency is improved, and the intergranular sensitization tendency of materials is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of microchannel heat exchangers, and in particular to a manufacturing device and a manufacturing method for a microchannel heat exchanger core. Background Art

[0002] Microchannel heat exchanger is a highly efficient and compact heat exchange equipment that achieves excellent heat transfer performance by transferring fluid in tiny channels. As a typical representative of microchannel heat exchangers, printed circuit board heat exchangers have higher reliability and broad application prospects in the fields of nuclear energy, petrochemical industry, oil and gas technology, aerospace, fuel cells and new energy. The manufacturing path of printed circuit board heat exchangers can be summarized into three main parts: channel plate etching, heat exchanger core diffusion welding, and external head pipe box welding. The heat exchanger core diffusion welding is the most important part of the manufacturing of printed circuit board heat exchangers.

[0003] The Chinese invention patent with a publication date of March 18, 2022 and publication number CN114192961A proposes a method for gas pressurized diffusion welding of a thin-walled microchannel heat exchanger core, comprising the following steps: S1. Wipe off the oil stains on the plates, rinse with clean water, and dry the plates; S2. Spot weld the fittings around the upper and lower plates to form a heat exchanger core with the two plates; S3. Weld the upper end surface of the heat exchanger core in step S2 to form a closed cavity inside the heat exchanger core; S4. Diffusion weld the heat exchanger core in step S3, and the vacuum degree is below 1×10-2Pa; S5. Cut off the weld in step S3 and the area outside the weld, and fine-process to obtain the finished microchannel heat exchanger core.

[0004] The above-mentioned diffusion welding method is to first place the heat exchanger core in the furnace body, and then heat the furnace body to heat the heat exchanger core to the welding temperature, and then cool it with the furnace after welding. The above-mentioned diffusion welding method heats the heat exchanger core by heat transfer from the furnace body, and its heating speed is slow and time-consuming. In addition, it takes a lot of time for the furnace body temperature to be above 1000°C and then cooled to 150°C with the furnace, resulting in a long welding process time and low efficiency. In addition, stainless steel is prone to intergranular sensitization in the range of 400°C-700°C, which reduces the corrosion resistance of the material and reduces the service life of the material. Therefore, it is necessary to avoid this temperature range as much as possible during the processing process, and when the heating and cooling link must pass through this range, it should be passed as soon as possible. Therefore, the improvement of the heating and cooling speed of the present invention effectively improves the intergranular sensitization tendency of the heat exchanger material. Summary of the invention

[0005] In order to shorten the heating and cooling time of a heat exchanger core, the present application provides a method for manufacturing a microchannel heat exchanger core.

[0006] On the one hand, the present application proposes a method for manufacturing a microchannel heat exchanger core, the manufacturing method comprising: Preparation stage: forming a plurality of flow channels on the surface of the core plate, and stacking the core plates to form a core body, placing the core body in a diffusion welding device and applying a pre-tightening pressure to the core body, and evacuating the furnace body of the diffusion welding device; Heating stage: Step 1, heating the furnace body, and keeping the furnace body warm when the temperature reaches a first predetermined temperature, introducing a first inert gas into each flow channel of the core body through the air inlet of the diffusion welding device, and monitoring the temperature at the air outlet of the diffusion welding device until the temperature at the air outlet reaches a first predetermined temperature range; Step 2, continue to heat the furnace body and repeat step 1 until the temperature of the air outlet reaches a third predetermined temperature range, evacuate the furnace body and continue to heat the furnace body until the furnace body reaches a fourth predetermined temperature, keep the temperature, apply welding pressure to the core body, and stop heating and complete welding when the plastic deformation of the core body reaches a predetermined value, wherein the welding pressure is greater than the preload pressure; Cooling stage: a second inert gas of predetermined pressure and temperature is introduced into the furnace body, wherein the temperature of the second inert gas is lower than the first predetermined temperature; a third inert gas of different temperatures is introduced into each flow channel of the core body in turn to lower the temperature of the core body, and the introduction of the second inert gas is stopped until the temperature of the air outlet reaches a fifth predetermined temperature, wherein the fifth predetermined temperature is lower than the temperature value of the first predetermined temperature range.

[0007] The manufacturing method of the heat exchanger core provided in the present application improves the manufacturing method of the heat exchanger core. When diffusion welding is performed on the microchannel heat exchanger, an inert gas is introduced into the flow channel of the microchannel heat exchanger during the heating and cooling processes. The heat of the inert gas is used to heat the heat exchanger core during the heating stage. During the cooling stage, the heat exchanger core transfers heat to the inert gas so that the heat is quickly discharged and the heat exchanger core is cooled, thereby greatly improving the heating and cooling rates of the heat exchanger core, improving the production efficiency of the heat exchanger core, and helping to reduce the manufacturing cost of the heat exchanger core.

[0008] According to one aspect of the embodiment of the present application, wind hoods are respectively arranged between the air inlet and the core body and between the air outlet and the core body to introduce gas into the flow channel and to lead gas out of the flow channel.

[0009] According to one aspect of an embodiment of the present application, when the first inert gas and the third inert gas are introduced into the flow channel of the core body, the gas flow directions of the air inlet and the air outlet are repeatedly exchanged so that the gas flow directions in the air inlet and the air outlet are exchanged within a predetermined time.

[0010] According to one aspect of an embodiment of the present application, a switching frequency of the air inlet and the air outlet is 1 time / min.

[0011] According to one aspect of an embodiment of the present application, the first predetermined temperature is 300°C, the first predetermined temperature interval is 260°C-300°C, the third predetermined temperature interval is 860°C-900°C, and the fourth predetermined temperature is 1050°C.

[0012] According to one aspect of an embodiment of the present application, the heating rate of the furnace is 10° C. / min.

[0013] According to one aspect of an embodiment of the present application, the pressure of the second inert gas is 0.3 bar-3 bar, and the temperature is 25° C.-40° C.

[0014] According to one aspect of the embodiment of the present application, the temperature difference between two adjacent times of the third inert gas is 300° C.-450° C.

[0015] On the other hand, an embodiment of the present application also proposes a manufacturing device for a microchannel heat exchanger core, comprising a furnace body, a heating component, a first wind hood and a second wind hood, the furnace body having an inner cavity and an air inlet, an air outlet, an air inlet and an air outlet, the heating component being arranged on the furnace wall of the inner cavity, the first wind hood and the second wind hood having openings at both ends, wherein one end of the first wind hood is connected to the air inlet, and the other end is used to connect to the inlet of the core microchannel, one end of the second wind hood is connected to the air outlet, and the other end is used to connect to the outlet of the core microchannel, the air inlet and the air outlet are respectively used to introduce and discharge high-temperature or low-temperature gases into and out of the furnace body.

[0016] The manufacturing equipment for the microchannel heat exchanger core provided in the embodiment of the present application can, during the heating stage, introduce high-temperature inert gas into the heat exchanger core through the first wind hood so that the heat exchanger core quickly reaches the welding temperature. During the cooling stage, the heat in the heat exchanger core can be quickly discharged through the second wind hood to cool the heat exchanger core, thereby greatly improving the heating and cooling rates of the heat exchanger core and improving the production efficiency of the heat exchanger core.

[0017] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a flow chart of a method for manufacturing a microchannel heat exchanger core according to an embodiment of the present application; Figure 2It is a schematic diagram of a core plate of a structural core in the welding process of the method for manufacturing a microchannel heat exchanger core in an embodiment of the present application; Figure 3 yes Figure 2 Heat transfer diagram of the structural core during welding; Figure 4 It is a schematic diagram of a core plate of a structural core during the welding process of the method for manufacturing a microchannel heat exchanger core in an embodiment of the present application; Figure 5 yes Figure 4 Heat transfer diagram of the structural core during welding; Figure 6 It is a thermal field diagram of the core during the heating process of the manufacturing method of the microchannel heat exchanger core of the embodiment of the present application; Figure 7 yes Figure 6 A partial enlarged view of the middle A; Figure 8 It is a thermal field diagram of the core during the cooling process of the manufacturing method of the microchannel heat exchanger core of the embodiment of the present application; Fig. 9 yes Figure 8 A partial enlarged view of point B in the middle; Fig.10 It is a schematic structural diagram of a manufacturing device for a microchannel heat exchanger core according to an embodiment of the present application.

[0019] In the accompanying drawings, 1 is a core plate, 2 is a flow channel, 3 is a core body, 10 is a furnace body, 11 is an inner cavity, 12 is an air inlet, 13 is an air outlet, 14 is an air inlet, 15 is an air outlet, 20 is a first wind hood, and 30 is a second wind hood. DETAILED DESCRIPTION

[0020] The following detailed description and drawings of the embodiments of the present application are used to illustrate the principles of the present application, but cannot be used to limit the scope of the present application, that is, the present application is not limited to the described embodiments.

[0021] In the description of this application, it should be noted that, unless otherwise specified, "multiple" means more than two; the terms "upper", "lower", "left", "right", "inner", "outer", etc., indicating directions or positional relationships, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting this application. In addition, the terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0022] Reference to "embodiments" in this application 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 in this application may be combined with other embodiments.

[0023] In the related art, in order to prevent the radiator core from causing material performance degradation, deformation or cracking during the welding process, gradual heating or cooling is usually required to reduce thermal stress. However, the gradual heating or cooling usually takes a long time, resulting in a long process time and low efficiency for the radiator core welding.

[0024] Based on this, the embodiment of the present application provides a method for manufacturing a microchannel heat exchanger core to solve the above technical problems. The method for manufacturing a microchannel heat exchanger core provided by the embodiment of the present application is introduced below.

[0025] like Figures 1 to 9 As shown, the present application provides a method for manufacturing a microchannel heat exchanger core, which may include the following steps: Preparation stage: multiple flow channels 2 are formed on the surface of the core plate 1, and the core plates 1 are stacked to form a core body 3, the core body 3 is placed in a diffusion welding device and pre-tightening pressure is applied to the core body, and the furnace body of the diffusion welding device is evacuated. Pre-tightening can ensure that the contact surfaces between two or more core plates 1 fit tightly, eliminate gaps, and create good contact conditions for subsequent welding processes. Pre-tightening also helps promote atomic diffusion between the joint surfaces of the core plates, thereby achieving effective welding connections. Pre-tightening can also increase the pressure on the joint surface, thereby improving the connection strength after welding. The diffusion welding equipment includes a furnace body and an air inlet and an air outlet connected to the furnace body.

[0026] Heating stage: Step 1, heating the furnace body, and keeping the furnace body warm when the temperature reaches a first predetermined temperature, introducing a first inert gas into each flow channel of the core body through the air inlet of the diffusion welding equipment, and monitoring the temperature at the air outlet of the diffusion welding equipment until the temperature of the air outlet reaches a first predetermined temperature range.

[0027] Step 2, continue to heat the furnace body and repeat step 1 until the temperature of the air outlet reaches the third predetermined temperature range, evacuate the furnace body and continue to heat the furnace body until the furnace body reaches the fourth predetermined temperature, keep the temperature, apply welding pressure to the core body, and stop heating and complete welding when the plastic deformation of the core body reaches a predetermined value, wherein the welding pressure is greater than the preload pressure. Gradual heating helps to reduce thermal stress caused by temperature changes and reduce the risk of deformation and cracking of workpieces.

[0028] It should be noted that gradually raising the temperature of the core to the welding temperature helps to achieve uniform temperature distribution inside the workpiece, reduce temperature gradients, and avoid local overheating. It is also conducive to promoting uniform phase transformation, such as austenitization and pearlite transformation, so as to obtain a more optimized microstructure. At the same time, it can also effectively reduce the residual stress inside the core and improve its fatigue life and stress corrosion resistance.

[0029] In addition, it should be noted that stainless steel materials are prone to intergranular sensitization in the range of 400°C-700°C, which reduces the corrosion resistance and service life of the material. Therefore, during the processing, it is necessary to avoid this temperature range as much as possible, and when the heating and cooling links must pass through this range, it should be passed as quickly as possible. Therefore, the improvement of the heating and cooling speed of the present invention effectively improves the intergranular sensitization tendency of the heat exchanger material.

[0030] Cooling stage: a second inert gas of predetermined pressure and temperature is introduced into the furnace body, wherein the temperature of the second inert gas is lower than the first predetermined temperature; a third inert gas of different temperatures is introduced into each flow channel of the core body in turn to lower the temperature of the core body, and the introduction of the second inert gas is stopped until the temperature of the air outlet reaches a fifth predetermined temperature, wherein the fifth predetermined temperature is lower than the temperature value of the first predetermined temperature range.

[0031] Therefore, when diffusion welding is performed on the microchannel heat exchanger, an inert gas is introduced into the flow channel of the microchannel heat exchanger during the heating and cooling processes. The heat of the inert gas is used to heat the heat exchanger during the heating stage; during the cooling stage, the heat exchanger transfers heat to the inert gas so that the heat is quickly discharged and the heat exchanger is cooled, thereby greatly improving the heating and cooling rates of the heat exchanger core, improving the production efficiency of the heat exchanger core, and helping to reduce the manufacturing cost of the heat exchanger core.

[0032] During the preparation stage, the core plate 1 can be made of a plate with a length of 1200mm, a width of 600mm, a thickness of 2mm, and a flow channel diameter of 2mm. The material of the core plate can be GH4169, which is a precipitation-strengthened nickel-based high-temperature alloy with good fatigue resistance, radiation resistance, oxidation resistance, corrosion resistance, as well as good processing performance and welding performance. It can manufacture parts of various complex shapes. The number of stacked layers of the core body can be 120 layers of primary side plates and 120 layers of secondary side plates. The core body is placed between diffusion welding equipment, and pre-spot welding can be performed between each core plate. Laser welding or argon arc welding can be used for spot welding. The embodiment of the present application preferably uses argon arc welding. The axial preload pressure applied to the core body can be 0.5MPa-1MPa. The furnace body is evacuated, and when the vacuum degree reaches 1×10 -2 Pa, start heating the furnace body.

[0033] During the heating stage, the first inert gas can be high-purity argon. Argon is used as a protective gas during welding, which can effectively isolate the air and prevent the welding area from contacting oxygen, nitrogen and other gases in the air, thereby reducing oxidation and contamination of the welding material. The gas pressure of the first inert gas can be 0.8 bar.

[0034] During the cooling stage, the second inert gas and the third inert gas can be high-purity nitrogen, and argon can form a protective atmosphere during the cooling process to prevent the workpiece from contacting oxygen in the air. The gas pressure of the second inert gas and the third inert gas can be 0.8 bar.

[0035] In some embodiments, in order to allow more first inert gas and second inert gas to enter each flow channel of the core body, the manufacturing method further includes: respectively arranging wind shields between the air inlet and the core body and between the air outlet and the core body to introduce gas into the flow channel and to lead gas out of the flow channel. The wind shield material should be compatible with the air inlet and outlet or the core body material so as not to damage the performance of the core body. In this embodiment, the wind shield material can be selected from 316L stainless steel, and the wind shield and the core body can be sealed by argon arc welding.

[0036] It should be noted that the sealing part is allowed to have a poor seal of no more than 1 / 3 of the total sealing length. The wind hood only plays a guiding role. A small amount of leakage will not affect the main flow state of the inert gas. It is sufficient to ensure that more than 80% of the fluid is in circulation. The process cost brought by full sealing is relatively high, so there is no need to require full sealing.

[0037] In some embodiments, when the first inert gas and the third inert gas are introduced into the flow channel of the core body, the gas flow directions of the air inlet and the air outlet are repeatedly exchanged so that the gas flow directions in the air inlet and the air outlet are exchanged within a predetermined time, that is, the air inlet is converted to the air outlet, and the air outlet is converted to the air inlet, so that the flow direction of the inert gas changes. The main purpose is that when a large or complex-shaped workpiece is heated, for example, when the core plate length exceeds 1m, a large temperature gradient may be generated, resulting in thermal stress concentration. Therefore, by switching the flow directions of the air inlet and the air outlet, the temperature gradient in the inlet and outlet directions of the heat exchanger core flow channel can be reduced, the thermal stress concentration during heating and cooling can be reduced, and the performance degradation, deformation or cracks of the core plate can be avoided to ensure the welding quality.

[0038] Furthermore, the reversing frequency of the air inlet and the air outlet is 1 time / min, that is, the air inlet and the air outlet are reversed once every minute to eliminate thermal stress concentration and ensure welding quality.

[0039] In some embodiments, the first predetermined temperature is 300°C, the first predetermined temperature interval is 260°C-300°C, the third predetermined temperature interval is 860°C-900°C, and the fourth predetermined temperature is 1050°C. It should be noted that the core is quickly heated to 260°C-300°C, which is usually lower than the welding temperature. The purpose of this is to shorten the heating time and reduce the residence time of the core at high temperature, thereby reducing oxidation and other possible thermal effects.

[0040] In some embodiments, the heating rate of the furnace body is 10°C / min, that is, the temperature in the furnace body is gradually heated to 860°C-900°C, the main purpose of which is to continue heating the workpiece to reduce thermal stress and avoid degradation of material properties. The heating rate from the third predetermined temperature to the fourth predetermined temperature is 10°C / min to ensure uniform temperature of the workpiece, reduce thermal stress caused by temperature gradient, and prepare for reaching the welding temperature.

[0041] In some embodiments, the holding time after reaching the fourth predetermined temperature is 4h-6h. The long holding time helps to even out the temperature inside the material, reduce the internal stress caused by the temperature gradient, and ensure that the entire core body has a consistent microstructure and performance. At the same time, it also helps to relieve the stress caused by rapid heating or cooling, reduce the risk of deformation and cracking of the workpiece, and improve dimensional stability.

[0042] In some embodiments, the second inert gas has a pressure of 0.3 bar to 3 bar and a temperature of 25° C. to 40° C. By introducing the inert gas at a lower temperature, the inert gas can provide a mild cooling environment, which helps to control the cooling rate of the core, thereby preventing thermal stress and reducing deformation.

[0043] In some embodiments, the temperature difference between two adjacent third inert gases is 300°C-450°C. By setting the temperature difference of 300°C-450°C, it helps to reduce the thermal stress caused by temperature changes, thereby reducing the risk of deformation and cracking of the workpiece, and can promote uniform phase change, improve the mechanical properties of the material, effectively reduce the residual stress inside the workpiece, and increase its fatigue life.

[0044] On the other hand, Fig.10 As shown, the embodiment of the present application also proposes a manufacturing device for a microchannel heat exchanger core, including a furnace body 10, a heating assembly, a first wind hood 20 and a second wind hood 30.

[0045] The furnace body 10 has an inner cavity 11 and an air inlet 12, an air outlet 13, an air inlet 14 and an air outlet 15. The inner cavity 11 is used to place the workpiece, and a pressurizing mechanism may also be provided in the inner cavity 11 to apply welding pressure to the core.

[0046] The heating assembly is arranged on the furnace wall of the inner cavity 11, wherein the heating assembly is composed of a plurality of resistance heating elements, which can be installed in the inner lining of the furnace wall to perform radiation heating on the furnace body, and the resistance heating element can be a resistance wire or resistance belt wound into a coil, which is installed inside the furnace wall to transfer heat to the workpiece in the furnace by radiation. In addition, the resistance heating element can also be installed at the bottom of the furnace body, which also heats the workpiece by radiation and can provide a uniform heating environment.

[0047] The first wind hood 20 and the second wind hood 30 can both be made of 316L stainless steel. Both ends of the first wind hood 20 and the second wind hood 30 have openings, wherein one end of the first wind hood 20 is connected to the air inlet 12, and the other end is used to connect to the inlet of the core microchannel, one end of the second wind hood 30 is connected to the air outlet 13, and the other end is used to connect to the outlet of the core microchannel, the air inlet 14 and the air outlet 15 are respectively used to introduce and discharge high-temperature or low-temperature gas into the furnace body.

[0048] The manufacturing equipment for the microchannel heat exchanger core provided in the embodiment of the present application can, during the heating stage, introduce high-temperature inert gas into the heat exchanger core through the first wind hood 20, so that the heat exchanger core quickly reaches the welding temperature. During the cooling stage, the heat in the heat exchanger core can be quickly discharged through the second wind hood 30 to cool the heat exchanger core, thereby greatly improving the heating and cooling rates of the heat exchanger core and improving the production efficiency of the heat exchanger core.

[0049] The manufacturing method of the microchannel heat exchanger core is further introduced below in conjunction with specific embodiments.

[0050] S1, select a core plate with a plate length of 1200mm, a plate width of 600mm, and a plate thickness of 2mm, use chemical etching to prepare a flow channel on the core plate, the flow channel diameter is 2mm, stack the above 120 core plates of the same specification to form a core body, and perform pre-spot welding, and the spot welding adopts argon arc welding. The core body is placed in the diffusion welding equipment, that is, the furnace body, and the air inlet and outlet of the furnace body are connected with the surface of the core body with the flow channel. The bottom seal is made by argon arc welding, and the sealing part is allowed to be no more than 1 / 3 of the total sealing length. In this embodiment, the material of the wind hood is 316L stainless steel, and the axial pre-tightening pressure is applied to the core body, and the pre-tightening pressure is 0.5MPa-1MPa.

[0051] S2, close the furnace door and evacuate the furnace. When the vacuum degree reaches 1×10 -2 Pa, the furnace body began to be heated at a heating rate of 10°C / min, and the furnace body was kept warm when the temperature reached 300°C.

[0052] S3, introduce 0.8 bar high-purity argon gas into the core flow channel through the air inlet, and start the flow circulation. The circulation system changes direction once every 1 minute, that is, the flow direction of the air inlet and outlet changes once every 1 minute.

[0053] At the same time, monitor the temperature of the core air inlet and outlet. When the air outlet gas temperature is ≥260℃, the furnace body starts to continue heating at a heating rate of 10℃ / min, and heats to 500℃ for insulation. At this time, increase the temperature of the argon gas at the air inlet of the furnace body to 500℃; when the air outlet gas temperature is ≥460℃, the furnace body starts to continue heating at a heating rate of 10℃ / min, and heats to 700℃ for insulation. At this time, gradually increase the temperature of the argon gas at the air inlet to 700℃; when the air outlet gas temperature is ≥660℃, the furnace body starts to continue heating at a heating rate of 10℃ / min, and heats to 900℃ for insulation. At this time, gradually increase the temperature of the argon gas at the air inlet to 900℃; when the air outlet gas temperature is ≥860℃, extract the argon gas in the furnace until the vacuum degree is ≤5×10 - 1 Pa, the furnace body began to continue heating, the heating rate was 10 ℃ / min, heated to 1050 ℃ and kept warm for 4h-6h, at this time began to apply 8MPa-13MPa welding pressure, until the welding deformation reached 15mm, stop heating.

[0054] S4, introduce 0.8 bar high-purity nitrogen into the furnace body, the nitrogen temperature is 25℃-40℃, and start the external cooling cycle, that is, introduce a fixed volume of nitrogen into the furnace body. A circulation pipeline is set outside the furnace body. After the nitrogen circulates through the circulation pipeline, it returns to the furnace body, and this cycle repeats.

[0055] S5, introduce 0.8 bar high-purity nitrogen into the core flow channel through the air inlet, and quickly increase the nitrogen temperature to 700℃, start the flow cycle, change the flow direction of the air inlet and outlet every 1 minute, monitor the gas temperature at the air outlet, ensure that the temperature drop rate of the gas outlet temperature is ≥60℃ / min, and adjust the gas flow rate when the requirement is not met; when the outlet temperature is ≤800℃, adjust the circulating gas temperature to 400℃, maintain the above cycle, monitor the gas temperature at the air outlet, ensure that the nitrogen temperature drop rate at the gas outlet is ≥60℃ / min, and adjust the gas flow rate when the requirement is not met; when the outlet temperature is ≤500℃, adjust the circulating gas temperature to 25℃, stop air intake when the outlet temperature is ≤250℃, and close the external cooling cycle at the same time to complete the heat exchanger core welding.

[0056] S6, the welded core is subjected to a heat treatment process to obtain the best comprehensive mechanical properties.

[0057] The above is only a specific implementation of the present application. Those skilled in the art can clearly understand that for the convenience and simplicity of description, the specific working processes of the systems, modules and units described above can refer to the corresponding processes in the aforementioned method embodiments, and will not be repeated here. It should be understood that the protection scope of the present application is not limited to this. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed in this application, and these modifications or replacements should be included in the protection scope of this application.

Claims

1. A method for manufacturing a microchannel heat exchanger core, characterized in that: The following steps are involved: Preparation stage: forming a plurality of flow channels on the surface of the core plate, and stacking the core plates to form a core body, placing the core body in a diffusion welding device and applying a pre-tightening pressure to the core body, and evacuating the furnace body of the diffusion welding device; Heating stage: Step 1, heating the furnace body, and keeping the furnace body warm when the temperature reaches a first predetermined temperature, introducing a first inert gas into each flow channel of the core body through the air inlet of the diffusion welding device, and monitoring the temperature at the air outlet of the diffusion welding device until the temperature at the air outlet reaches a first predetermined temperature range; Step 2, continue to heat the furnace body and repeat step 1 until the temperature of the air outlet reaches a third predetermined temperature range, evacuate the furnace body and continue to heat the furnace body until the furnace body reaches a fourth predetermined temperature, keep the temperature, apply welding pressure to the core body, and stop heating and complete welding when the plastic deformation of the core body reaches a predetermined value, wherein the welding pressure is greater than the preload pressure; Cooling stage: a second inert gas of predetermined pressure and temperature is introduced into the furnace body, wherein the temperature of the second inert gas is lower than the first predetermined temperature; a third inert gas of different temperatures is introduced into each flow channel of the core body in turn to lower the temperature of the core body, and the introduction of the second inert gas is stopped until the temperature of the air outlet reaches a fifth predetermined temperature, wherein the fifth predetermined temperature is lower than the temperature value of the first predetermined temperature range.

2. The method for manufacturing a microchannel heat exchanger core according to claim 1, characterized in that: Wind shields are respectively arranged between the air inlet and the core body and between the air outlet and the core body to introduce gas into the flow channel and to lead gas out of the flow channel.

3. The method for manufacturing a microchannel heat exchanger core according to claim 1, characterized in that: When the first inert gas and the third inert gas are introduced into the flow channel of the core body, the gas flow directions of the air inlet and the air outlet are repeatedly exchanged so that the gas flow directions in the air inlet and the air outlet are exchanged within a predetermined time.

4. The method for manufacturing a microchannel heat exchanger core according to claim 3, characterized in that: The switching frequency of the air inlet and the air outlet is 1 time / min.

5. The method for manufacturing a microchannel heat exchanger core according to any one of claims 1 to 4, characterized in that: The first predetermined temperature is 300°C, the first predetermined temperature range is 260°C-300°C, the third predetermined temperature range is 860°C-900°C, and the fourth predetermined temperature is 1050°C.

6. The method for manufacturing a microchannel heat exchanger core according to any one of claims 1 to 4, characterized in that: The heating rate of the furnace is 10°C / min.

7. The method for manufacturing a microchannel heat exchanger core according to any one of claims 1 to 4, characterized in that: The pressure of the second inert gas is 0.3 bar-3 bar, and the temperature is 25° C.-40° C.

8. The method for manufacturing a microchannel heat exchanger core according to any one of claims 1 to 4, characterized in that: The temperature difference between two adjacent third inert gas injections is 300°C-450°C.

9. A manufacturing device for a microchannel heat exchanger core, characterized in that: The invention comprises a furnace body (10), a heating component, a first wind hood (20) and a second wind hood (30), wherein the furnace body (10) has an inner cavity (11) and an air inlet (12), an air outlet (13), an air inlet (14) and an air outlet (15), wherein the heating component is arranged on the furnace wall of the inner cavity (11), and both ends of the first wind hood (20) and the second wind hood (30) have openings, wherein one end of the first wind hood (20) is connected to the air inlet (12), and the other end is used to connect to the inlet of the core microchannel, and one end of the second wind hood (30) is connected to the air outlet (13), and the other end is used to connect to the outlet of the core microchannel, and the air inlet (14) and the air outlet (15) are used to respectively introduce and discharge high-temperature or low-temperature gas into and out of the furnace body.

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