Positive pressure environment aluminum matrix composite welding device and method

Abstract

The welding device comprises a high-pressure cabin, a welding platform is arranged in the high-pressure cabin, the high-pressure cabin is externally connected with a gas tank, and the aluminum-based composite material is welded through environment pressure, mechanical movement and automatic temperature control under the inert atmosphere and the pressure environment of 0.5 MPa-1. 0 MPa. High-quality welding of the aluminum-based composite material under the inert gas and positive pressure environment is achieved, and the solidification part of a welding pool is forcibly cooled, so that the solidification part is rapidly cooled and solidified, the microstructure is refined, and the density of a welding seam is improved; the high-quality welding method for aluminum-based composite material products in various to-be-welded form areas is achieved, and the method has the advantages of being high in welding density, uniform and solidified in weld joint structure, wide in welding application range and low in stress deformation.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum alloy welding, and in particular to a device and method for welding aluminum-based composite materials in a positive pressure environment. Background Art

[0002] Aluminum-based composite materials have the characteristics of high specific strength, high stiffness, high modulus, corrosion resistance, etc. due to the presence of ceramic reinforcement phases such as SiC and TiB2. They are widely used in aviation, aerospace, weapons, transportation, electronics and other fields.

[0003] According to Henry's law, the solubility of a gas in a liquid is proportional to its partial pressure. Forming aluminum alloys under positive pressure, such as in differential pressure casting and autoclave casting (generally above 0.5 MPa), effectively reduces hydrogen precipitation and the likelihood of pore formation under system pressure. Forming under positive pressure can effectively compensate for tiny shrinkage cavities, resulting in denser castings. Positive pressure also promotes grain refinement, comprehensively improving mechanical properties and significantly enhancing material quality.

[0004] When aluminum-based composite products need to be welded, the distribution state of the ceramic phase in the molten pool will be redistributed after the welding area melts and re-solidifies, making it difficult to achieve uniform distribution. In addition, when solidified under normal conditions, defects such as pores and tiny shrinkage are easily generated, and the density is poor, making this area the weakest position of the product, seriously affecting the use of the product, thereby restricting the application scope of aluminum-based composite materials.

[0005] If aluminum-based composite materials are combined with a positive pressure environment and welded into shape in a positive pressure environment, it can not only ensure the high specific strength, high stiffness and other characteristics of the product, but also ensure the density of the welding area and the uniformity of the mechanical properties of the product.

[0006] At present, in the research on aluminum-based composite material welding, the welding environment is mainly atmospheric environment and vacuum environment, and the pressure environment is mainly normal pressure environment and pressurized environment.

[0007] Atmosphere + normal pressure environment: The invention with publication number CN1895830A discloses a particle-reinforced aluminum-based composite material plasma arc welding technology, and the key technology is to add some metal elements to the molten pool; the invention with publication number CN 117245201 A discloses an intermediate layer for aluminum-based composite material welding and its production method and welding method; the invention with publication number CN100396416C discloses a discontinuously reinforced aluminum-based composite material tungsten inert gas arc welding weld in situ reinforcement method, by installing an electromagnetic stirring device on the welding gun and filling alloy elements to achieve the welding of aluminum-based composite materials; the document "Research on Stir Friction Welding Process of 6061 Aluminum-based Silicon Carbide Composite Material" (Zhao Xiaoqiang) explores the influence of different stirring parameters on the welding zone. The welding environment of the above patents and documents is an atmospheric environment. This method is prone to produce oxidation inclusions, and solidification in an atmospheric environment is not conducive to material densification, resulting in reduced performance in this area.

[0008] Atmosphere + pressurized environment: The invention with announcement number CN 105618885 B discloses a method for forming a reinforced phase reinforced composite weld structure material by regulating and controlling. This method performs welding by applying a certain pressure under a certain temperature and ultrasonic field; the invention with publication number CN1686659A discloses an ultrasonic-resistance welding method for aluminum-based composite materials. This method is mainly achieved by ultrasonic and resistance heating, and then applying a certain welding pressure. Although the above method applies a certain pressure, it is a mechanical pressure and cannot suppress the precipitation of [H], resulting in the formation of pores and easily forming oxide inclusions.

[0009] Vacuum + normal pressure environment: The invention with publication number CN110293304A discloses a method for electron beam welding of SiCp particle-reinforced aluminum-based composite materials. This method uses an electron beam as a heat source and places an intermediate layer containing a reinforcing phase between base materials for welding. The welding environment of the above method is vacuum. Welding under negative pressure results in poor material density and easy precipitation of [H] in the material, making it difficult to ensure the welding quality at this location.

[0010] Vacuum + pressurized environment: The document "Vacuum Diffusion Welding of Aluminum-Based Composite Materials and Analysis of Their Microstructure and Performance" (Cheng Ling) studied the effects of different vacuum diffusion welding process parameters on the shear properties of the welded surface of aluminum-based composite materials. Although this method can reduce oxidation, the mechanical pressure of the vacuum machine can easily cause the precipitation of [H] in the material, thereby forming pore defects. In addition, this welding method has high requirements on the welding shape, and some complex shapes will be difficult to weld.

[0011] In summary, there are various technical difficulties in welding aluminum-based composite materials in vacuum environments, normal pressure environments and pressurized environments. Summary of the Invention

[0012] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide a positive pressure environment aluminum-based composite material welding device and method, which realizes high-quality welding method of aluminum-based composite materials products in various welding areas through automated control of environmental pressure, mechanical movement, etc. under inert atmosphere and pressure environment of 0.5MPa to 1.0MPa, and has the advantages of high welding density, uniform solidification of weld structure, wide range of welding applications, and low stress deformation.

[0013] In order to achieve the above object, the technical solution of the present invention is:

[0014] A positive pressure environment aluminum-based composite material welding device, comprising a high-pressure chamber 1, on which are provided a pressure-reducing automatic control valve 11-1 connected to a pressure-reducing pipe 11, a high-pressure chamber pressure gauge 5, and a vacuum pump 6;

[0015] A welding platform 3 is provided in the hyperbaric chamber 1. The welding platform 3 is arranged on a track 4. A matching welding robot 2 is provided next to the welding platform 3. The signal end of the welding robot 2 is controlled by a computer 13. The front end of the mechanical arm of the welding robot 2 is provided with an inert gas air cooling pipe 2-1, which is connected to a gas storage tank 8.

[0016] The high-pressure chamber 1 is also connected to the boosting automatic control valve 10 - 1 through the boosting pipe 10 , and the boosting automatic control valve 10 - 1 is connected to the gas drying equipment 9 , the gas storage tank 8 and the nitrogen generator 7 in sequence.

[0017] The hyperbaric chamber 1 is further provided with an observation window 1-2 and a hyperbaric chamber safety valve 1-3, a hyperbaric chamber door 1-1 is provided on one side of the hyperbaric chamber 1, and an infrared temperature sensor 12 is further provided on the inner wall of the hyperbaric chamber 1.

[0018] The gas storage tank 8 is provided with a gas storage tank pressure gauge 8-1, and a gas storage tank safety valve 8-2 is provided on the top.

[0019] A positive pressure environment aluminum-based composite material welding method comprises the following steps:

[0020] Step 1: Bevel the two SiC / TiB2 reinforced aluminum matrix composite workpieces to be butt-welded, clean them, and dry them. Install the two workpieces on the welding platform 3 in the hyperbaric chamber 1. Adjust the position of the welding platform 3 via the track 4, calibrate the welding gun positioning of the welding robot 2, set the welding path and welding parameters on the computer 13, and after confirmation, close the hyperbaric chamber door 1-1.

[0021] Step 2: Start the vacuum pump 6 to remove the air from the hyperbaric chamber 1. When the vacuum degree is ≤0.05 MPa, start the nitrogen generator 7 and build up the inert gas environment pressure in the hyperbaric chamber 1 through the gas storage tank 8, the booster pipe 10 and the booster automatic control valve 10-1 until the pressure meets the design requirement of 0.5 MPa to 1.0 MPa.

[0022] Step 3: After step 2 is completed, the welding robot 2 is started and welding is started according to the set path and welding parameters. The welding material is SiC / TiB2 reinforced aluminum-based composite wire of the same material as the base material. The welding process is regulated according to the pressure in the high-pressure chamber 1 through the boost automatic control valve 10-1 and the decompression automatic control valve 11-1 to ensure that the pressure in the chamber is relatively constant at ±0.05MPa. During the welding process, the inert gas air cooling pipe 2-1 is turned on to force cooling of the solidified part of the welding pool, and the temperature of the workpiece after cooling is monitored by the infrared temperature sensor 12;

[0023] Step 4: After welding is completed, close the boost automatic control valve 10-1 and the decompression automatic control valve 11-1, start the vacuum pump 6 to remove the inert gas in the high-pressure chamber 1, and after the vacuum degree reaches ≤0.05MPa, turn off the vacuum pump 6, open the decompression automatic control valve 11-1, restore the high-pressure chamber 1 to the atmospheric environment, open the high-pressure chamber door 1-1, and take out the welded workpiece.

[0024] The welding parameters of step 1 are: deposition current: 100A-120A, deposition voltage: 11.5V-12.5V.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] (1) Step 2 of the present invention achieves high-quality welding of aluminum-based composite materials under an inert gas and positive pressure environment. Compared with welding under a conventional atmospheric or vacuum environment, the weld structure is denser, without component segregation, inclusions, pinholes and other defects.

[0027] (2) In step 3 of the present invention, the solidified portion of the welding molten pool is forced to cool, so that the weld is rapidly cooled and solidified, the microstructure is refined, and the density of the weld is improved.

[0028] In summary, the process of the present invention has the advantages of high welding density, uniform weld solidification, wide welding application range, and low stress deformation. It can be used not only for repair welding of aluminum-based composite materials under an inert gas positive pressure environment, but also for arc additive manufacturing under an inert gas positive pressure environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the aluminum-based composite material welding system in a medium- and high-pressure environment of the present invention.

[0030] In the figure, 1. Hyperbaric chamber, 1-1. Hyperbaric chamber door, 1-2. Observation window, 1-3. Hyperbaric chamber safety valve, 2. Welding robot, 2-1. Inert gas air cooling pipe, 3. Welding platform, 4. Track, 5. Hyperbaric chamber pressure gauge, 6. Vacuum pump, 7. Nitrogen generator, 8. Gas storage tank, 8-1. Gas storage tank pressure gauge, 8-2. Gas storage tank safety valve, 9. Gas drying equipment, 10. Boosting pipe, 10-1. Boosting automatic control valve, 11. Decompression pipe, 11-1. Decompression automatic control valve, 12. Infrared temperature sensor, 13. Computer.

[0031] Figure 2 It is a partial enlarged view of the welding robot 2 and the inert gas cooling pipe 2-1 in the present invention.

[0032] Figure 3 The diagram in the middle is the result of the gold phase comparison, where: Figure 3 (a) Metallographic results of welding specimens under normal pressure, Figure 3 (b) in the figure is the metallographic result of the sample welded using this method. DETAILED DESCRIPTION

[0033] In order to more clearly illustrate the implementation of the present method, those skilled in the art can more clearly understand the advantages and usage of the present method through this specification. The structure, advantages and specific implementation methods of the present method are now described in detail with reference to the accompanying drawings.

[0034] Reference Figure 1 、 Figure 2 A positive pressure environment aluminum-based composite material welding device includes a high-pressure chamber 1, on which a pressure-reducing automatic control valve 11-1 connected to a pressure-reducing pipe 11, a high-pressure chamber pressure gauge 5, and a vacuum pump 6 are provided;

[0035] A welding platform 3 is provided in the high-pressure chamber 1. The welding platform 3 is provided on a track 4 and can be adjusted in position by movement. A welding robot 2 is provided next to the welding platform 3. The signal end of the welding robot 2 is controlled by a computer 13. Figure 2 An inert gas air cooling pipe 2-1 is provided at the front end of the robotic arm of the welding robot 2, and the inert gas air cooling pipe 2-1 is connected to the gas storage tank 8; wherein the inert gas air cooling pipe 2-1 moves synchronously with the robotic arm of the welding robot 2, is located at the rear side of the robotic arm welding gun, and the gas of the inert gas air cooling pipe 2-1 comes from the gas storage tank 8.

[0036] The high-pressure chamber 1 is also connected to the boosting automatic control valve 10 - 1 through the boosting pipe 10 , and the boosting automatic control valve 10 - 1 is connected to the gas drying equipment 9 , the gas storage tank 8 and the nitrogen generator 7 in sequence.

[0037] The hyperbaric chamber 1 is further provided with an observation window 1-2 and a hyperbaric chamber safety valve 1-3, a hyperbaric chamber door 1-1 is provided on one side of the hyperbaric chamber 1, and an infrared temperature sensor 12 is further provided on the inner wall of the hyperbaric chamber 1.

[0038] The gas storage tank 8 is provided with a gas storage tank pressure gauge 8-1, and a gas storage tank safety valve 8-2 is provided on the top.

[0039] A positive pressure environment aluminum-based composite material welding method comprises the following steps:

[0040] Step 1: Bevel the two SiC / TiB2 reinforced aluminum-based composite workpieces to be butt-welded, clean them, and dry them. Install the two workpieces on the welding platform 3 in the high-voltage chamber 1. Adjust the position of the welding platform 3 via the track 4, calibrate the welding robot 2 welding gun positioning, set the welding path and welding parameters on the computer 13, and select deposition current: 100A-120A, deposition voltage: 11.5V-12.5V. After confirmation, close the high-voltage chamber door 1-1.

[0041] Step 2: Turn on the vacuum pump 6 to evacuate the air in the high-pressure chamber 1. When the vacuum degree is ≤0.05MPa, start the nitrogen generator 7, and build up the pressure of the high-pressure chamber 1 with an inert gas environment through the gas storage tank 8, the boost pipe 10 and the boost automatic control valve 10-1 until the pressure meets the design requirement of 0.5MPa~1.0MPa; the welding process is completed in an inert positive pressure environment to avoid the oxygen components in the atmospheric environment from generating oxidation inclusions on the aluminum matrix. At the same time, the liquid melt in the weld pool solidifies under pressure, which is beneficial to the densification of the weld structure, and avoids the precipitation of gases contained in the base material or welding material at high temperature under atmospheric pressure or vacuum negative pressure environment, resulting in defects such as pinholes and pores.

[0042] Step 3: After step 2 is completed, start the welding robot 2 and start welding according to the set path and welding parameters. The welding material is SiC / TiB2 reinforced aluminum-based composite wire of the same material as the base material. During the welding process, the pressure in the high-pressure chamber 1 is adjusted by the boost automatic control valve 10-1 and the decompression automatic control valve 11-1 according to the pressure in the high-pressure chamber 1 to ensure that the pressure in the chamber is relatively constant at ±0.05MPa. During the welding process, the inert gas air cooling pipe 2-1 is turned on to force the solidification part of the welding pool to cool, and the workpiece after cooling is cooled. The workpiece temperature is monitored using an infrared temperature sensor 12; the infrared temperature sensor 12 is located 3-4 cm from the molten pool, and the body temperature does not exceed 100°C. The present invention utilizes an inert gas air cooling function. The air cooling port moves synchronously with the welding robot arm, following the path of the molten pool, instantly forcibly cooling the solidified molten pool. The workpiece temperature after cooling is monitored using infrared temperature measurement to ensure the degree of solidification undercooling in the molten pool area, refine the microstructure in this area, improve the density of the weld, and prevent the molten pool from segregating and agglomerating the reinforcing phase in the material during the free solidification process. At the same time, the system monitors the ambient pressure in real time and uses the boost and decompression pipelines to dynamically and stabilise the inert gas in the pressure chamber to maintain the consistency of the ambient pressure in the chamber.

[0043] Step 4: After welding is completed, close the boost automatic control valve 10-1 and the decompression automatic control valve 11-1, start the vacuum pump 6 to remove the inert gas in the high-pressure chamber 1, and after the vacuum degree reaches ≤0.05MPa, turn off the vacuum pump 6, open the decompression automatic control valve 11-1, restore the high-pressure chamber 1 to the atmospheric environment, open the high-pressure chamber door 1-1, and take out the welded workpiece.

[0044] Figure 3 (a) and (b) are the metallographic comparison results of the sample welded under normal pressure and the sample welded using this method. By comparison, we can see that: Figure 3 (a) The metallographic grain size of the welded sample under normal pressure is 6-6.5, and there is obvious silicon phase enrichment; Figure 3 In (b), the grain size of the sample welded using this method was significantly increased to 8-8.5, with uniform and fine grains and a uniform distribution of silicon phases, showing no significant enrichment. These results demonstrate that this method can effectively refine the grain size of welded joints, improve microstructure uniformity, and eliminate silicon phase segregation, resulting in a superior microstructure.

[0045] In summary, the present invention realizes linked control of pressure chamber pressure building, automatic positioning of workpiece welds, rapid welding fusion, air cooling treatment, and temperature monitoring, so that the weld pool solidifies in a pressurized inert gas environment, and refines the microstructure through rapid cooling, thereby achieving uniform weld structure and avoiding segregation of reinforcement phase and chemical composition.

Claims

1. A positive pressure environment aluminum-based composite material welding device, characterized in that: The high-pressure chamber (1) is provided with a pressure-reducing automatic control valve (11-1) connected to a pressure-reducing pipe (11), a high-pressure chamber pressure gauge (5), and a vacuum pump (6); A welding platform (3) is provided in the high-pressure chamber (1), the welding platform 3 is provided on a track (4), a welding robot (2) matched therewith is provided next to the welding platform (3), a signal end of the welding robot 2 () is controlled by a computer (13), an inert gas air-cooling pipe (2-1) is provided at the front end of the mechanical arm of the welding robot (2), and the inert gas air-cooling pipe (2-1) is connected to a gas storage tank (8); The high-pressure chamber (1) is also connected to a boosting automatic control valve (10-1) via a boosting pipe (10), and the boosting automatic control valve (10-1) is sequentially connected to a gas drying device (9), a gas storage tank (8), and a nitrogen generator (7).

2. The positive pressure environment aluminum-based composite material welding device according to claim 1, characterized in that: The high-pressure chamber (1) is also provided with an observation window (1-2) and a high-pressure chamber safety valve (1-3).

3. The positive pressure environment aluminum-based composite material welding device according to claim 1, characterized in that: A high-pressure chamber door (1-1) is provided on one side of the high-pressure chamber 1.

4. The positive pressure environment aluminum-based composite material welding device according to claim 1, characterized in that: An infrared temperature sensor 12 is also provided on the inner wall of the high-pressure chamber (1).

5. The positive pressure environment aluminum-based composite material welding device according to claim 1, characterized in that: The gas storage tank (8) is provided with a gas storage tank pressure gauge (8-1), and a gas storage tank safety valve (8-2) is provided on the top.

6. A positive pressure environment aluminum-based composite material welding method, based on the welding device according to any one of claims 1 to 5, characterized in that: The following steps are involved: Step 1: Bevel the two SiC / TiB2 reinforced aluminum-based composite material workpieces to be butt-welded, clean and dry them, install the two workpieces on the welding platform (3) in the high-pressure chamber (1), adjust the position of the welding platform (3) through the track (4), calibrate the welding robot (2) welding gun positioning, set the welding path and welding parameters on the computer (13), and close the high-pressure chamber door (1-1) after confirmation; Step 2: Start the vacuum pump (6) to remove the air in the high-pressure chamber (1). After the vacuum degree is ≤0.05MPa, start the nitrogen generator (7) and build up the pressure of the high-pressure chamber (1) with an inert gas environment through the gas storage tank (8), the booster pipe (10) and the booster automatic control valve (10-1) until the pressure meets the design requirement of 0.5MPa to 1.0MPa; Step 3: After step 2 is completed, the welding robot (2) is started and welding is started according to the set path and welding parameters. The welding material is SiC / TiB2 reinforced aluminum-based composite wire of the same material as the base material. During the welding process, the pressure in the high-pressure chamber (1) is adjusted through the boost automatic control valve (10-1) and the decompression automatic control valve (11-1) according to the pressure in the high-pressure chamber (1) to ensure that the pressure in the chamber is relatively constant at ±0.05MPa. During the welding process, the inert gas air cooling pipe (2-1) is turned on to force the solidification part of the welding pool to cool, and the temperature of the workpiece after cooling is monitored by an infrared temperature sensor (12); Step 4: After welding is completed, close the boost automatic control valve (10-1) and the decompression automatic control valve (11-1), start the vacuum pump (6) to remove the inert gas in the high-pressure chamber 1, and after reaching a vacuum degree of ≤0.05MPa, turn off the vacuum pump (6), open the decompression automatic control valve (11-1), restore the high-pressure chamber 1 to the atmospheric environment, open the high-pressure chamber door (1-1), and remove the welded workpiece.

7. The positive pressure environment aluminum-based composite material welding method according to claim 6, characterized in that: The welding parameters of step 1 are: deposition current: 100A-120A, deposition voltage: 11.5V-12.5V.

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