Low-temperature welding method for thin-walled sheet of automobile lightweight component

Abstract

This invention relates to the field of welding technology, specifically disclosing a low-temperature welding method for thin-walled plates used in lightweight automotive components. The welding method includes the following steps: S1: Raw material preparation, taking raw material, preparing a constant-temperature welding chamber and welding equipment, and a heating gun; S2: Raw material transfer, placing the raw material and welding equipment in the constant-temperature welding chamber; S3: Raw material cleaning, grinding the welding area of ​​the raw material to remove dirt, oxide scale, etc. This invention avoids the problems of excessive temperature difference and rapid cooling rate during welding of thin-walled plates under low-temperature external conditions by setting a constant-temperature welding chamber and limiting its ambient temperature to no lower than 0℃, preferably 7℃. Furthermore, the sealed constant-temperature environment ensures uniform and stable temperature in the welding space, preventing stress accumulation in the weld and base material due to environmental temperature changes, thereby reducing appearance defects such as warping, deformation, and wrinkles in the thin-walled plate.

Description

Technical Field

[0001] This invention relates to the field of welding technology, and in particular to a low-temperature welding method for thin-walled plates used in lightweight automotive components. Background Technology

[0002] With the rapid development of automotive lightweighting technology, thin-walled sheets such as aluminum alloys, high-strength steel, and composite material sheets are being widely used in automotive chassis, body panels, and structural support components.

[0003] Currently, conventional welding processes in the industry mostly employ high-temperature fusion welding, with welding temperatures generally exceeding 600℃. Furthermore, there is no environmental temperature control, no preheating before welding, and no post-weld heat preservation and slow cooling processes. Thin-walled plates are inherently thin, have low rigidity, and are extremely heat-sensitive. During high-temperature welding, localized heat concentration and excessive temperature gradients easily lead to defects such as welding deformation, warping, plate surface depressions, and weld cracks. Simultaneously, conventional processes do not limit the welding environment temperature. In low-temperature environments, the cooling rate of the base material and weld increases sharply, further exacerbating internal stress concentration, resulting in decreased mechanical properties and reduced corrosion resistance of the welded joint. Therefore, to address these issues, a low-temperature welding method for thin-walled plates used in lightweight automotive components has been proposed. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by proposing a low-temperature welding method for thin-walled plates used in lightweight automotive components.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A low-temperature welding method for thin-walled plates used in lightweight automotive components, comprising the following steps:

[0007] S1: Raw material preparation, take the raw material of the plate, prepare the constant temperature welding chamber and welding equipment, heating gun;

[0008] S2: Raw material transfer, placing the sheet metal raw materials and welding equipment in a constant temperature welding chamber;

[0009] S3: Cleaning of sheet material, grinding the welding area of ​​the sheet material to remove dirt, oxide scale, etc.;

[0010] S4: Fixing the sheet material: Use a clamping device to clamp and fix the sheet material, and move the welding equipment next to the sheet material to prepare for welding.

[0011] S5: Temperature adjustment of the constant temperature welding chamber. Adjust the temperature of the constant temperature welding chamber to greater than or equal to 0℃ and maintain a constant temperature.

[0012] S6: Preheating of board material: The board material is preheated using a heating gun. The board material is heated as a whole by moving the heating gun back and forth and up and down to preheat the board material comprehensively.

[0013] S7: Adjust the welding parameters of the welding equipment to set the welding temperature to 200℃-500℃;

[0014] S8: Welding, using welding equipment to weld preheated sheet metal raw materials;

[0015] S9: Post-weld treatment: After the sheet material is welded, it is continuously heated as a whole using a heating gun.

[0016] Preferably, the temperature of the constant temperature welding chamber in S5 is 7°C.

[0017] Preferably, the heating temperature of the heating gun in S6 and S9 is 450°C.

[0018] Preferably, in the S3 plate material cleaning step, fine sandpaper and steel wool are used to repeatedly polish the welding joint area of ​​the raw material plate. After polishing, the surface is wiped with anhydrous ethanol and left to air dry to remove residual oil and dust.

[0019] Preferably, in the S4 material fixing step, the clamping device uses a flexible silicone anti-slip pad to contact the surface of the material, so as to avoid the thin-walled material from being rigidly clamped and causing indentations and deformation.

[0020] Preferably, in the S6 board material preheating step, the distance between the heating gun and the board surface is maintained at 80-120mm, the moving speed is 10-15cm / s, and the horizontal and vertical cross-sweeping method is used for comprehensive heating. The preheating time is controlled at 3-5min to ensure that the overall temperature of the board material is uniform.

[0021] Preferably, the welding equipment in S7 is a pulsed argon arc welding machine, the welding current is set to 60-110A, the welding travel speed is 20-30cm / min, the shielding gas is high-purity argon, and the gas flow rate is controlled at 8-12L / min.

[0022] Preferably, in the S8 welding step, a segmented symmetrical welding method is adopted, and after the segment is completed, the entire weld seam is continuously repaired.

[0023] Preferably, in the S9 post-weld treatment step, the heating gun maintains the same spacing and movement as the preheating gun, and the heating time is not less than 15 minutes. After that, it is allowed to cool down naturally to room temperature in the constant temperature welding chamber. Sudden cooling by air is prohibited.

[0024] Preferably, the raw material of the sheet is automotive aluminum alloy sheet or high-strength steel cold-rolled sheet, and the constant temperature welding chamber is a closed heat-insulated structure, equipped with a circulating air distribution device to ensure that the temperature deviation throughout the entire area does not exceed ±1℃.

[0025] Compared with the prior art, the beneficial effects of the present invention are:

[0026] 1. In this invention, by setting up a constant temperature welding chamber and limiting the ambient temperature of the constant temperature welding chamber to no less than 0°C, preferably a constant temperature working environment of 7°C, the problem of excessive temperature difference and excessively fast cooling rate during the welding of thin-walled plates under low external working conditions is avoided. In addition, the sealed constant temperature environment can achieve uniform and stable temperature in the welding space, avoiding the accumulation of internal stress in the weld and base material due to ambient temperature changes, thereby reducing appearance defects such as warping, deformation, and wrinkles in the welding of thin-walled plates. At the same time, the pre-welding heating gun heats the raw material of the plate comprehensively, changing the traditional local fixed-point heating mode. It adopts a sweeping heating method that moves up and down and back and forth, so that the overall temperature of the raw material of the plate tends to be uniform, eliminating the welding stress caused by the temperature difference of the raw material itself, improving the flatness of the welded thin-walled components of automobiles, and eliminating the need for a large number of subsequent shaping and correction processes.

[0027] 2. In this invention, the welding temperature is controlled in the low-temperature range of 200℃-500℃, which is different from the traditional high-temperature fusion welding mode with large heat input. This reduces the range of the heat-affected zone and avoids the situation where the raw material of the bar becomes coarse-grained and the performance of the base material deteriorates due to high-temperature burning. In addition, the heating gun is set to a constant heating temperature of 450℃. Preheating before welding and continuous heating and slow cooling after welding can effectively suppress the generation of quenching cracks and delayed cracks in the weld and stabilize the metallographic structure and mechanical properties of the welded joint. Attached Figure Description

[0028] Figure 1 This is a flowchart of the low-temperature welding method for thin-walled plates used in lightweight automotive components proposed in this invention. Detailed Implementation

[0029] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0030] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0031] Reference Figure 1 A low-temperature welding method for thin-walled plates used in lightweight automotive components, comprising the following steps:

[0032] S1: Raw material preparation, take the raw material of the plate, prepare the constant temperature welding chamber and welding equipment, heating gun;

[0033] S2: Raw material transfer, placing the sheet metal raw materials and welding equipment in a constant temperature welding chamber;

[0034] S3: Cleaning of sheet material, grinding the welding area of ​​the sheet material to remove dirt, oxide scale, etc.;

[0035] S4: Fixing the sheet material: Use a clamping device to clamp and fix the sheet material, and move the welding equipment next to the sheet material to prepare for welding.

[0036] S5: Temperature adjustment of the constant temperature welding chamber. Adjust the temperature of the constant temperature welding chamber to greater than or equal to 0℃ and maintain a constant temperature.

[0037] S6: Preheating of board material: The board material is preheated using a heating gun. The board material is heated as a whole by moving the heating gun back and forth and up and down to preheat the board material comprehensively.

[0038] S7: Adjust the welding parameters of the welding equipment to set the welding temperature to 200℃-500℃;

[0039] S8: Welding, using welding equipment to weld preheated sheet metal raw materials;

[0040] S9: Post-weld treatment: After the sheet material is welded, it is continuously heated as a whole using a heating gun.

[0041] As a technical optimization of the present invention, the temperature of the constant temperature welding chamber in S5 is 7°C; the heating temperature of the heating gun in S6 and S9 is 450°C.

[0042] As a technical optimization of the present invention, in the S3 plate material cleaning step, fine sandpaper and steel wool are used to repeatedly polish the welding joint area of ​​the plate material. After polishing, the surface is wiped with anhydrous ethanol and left to air dry to remove residual oil and dust. In the S4 plate material fixing step, the clamping device uses flexible silicone anti-slip pads to contact the plate surface to avoid the thin-walled plate material from being rigidly clamped and causing indentations and deformation. In the S6 plate material preheating step, the distance between the heating gun and the plate surface is maintained at 80-120mm, the moving speed is 10-15cm / s, and a horizontal and vertical cross-sweeping method is used for comprehensive heating. The preheating time is controlled at 3-5min to ensure that the overall temperature of the plate material is uniform.

[0043] As a technical optimization of the present invention, in step S7, a pulsed argon arc welding machine is selected as the welding equipment, the welding current is set to 60-110A, the welding travel speed is 20-30cm / min, and the shielding gas is high-purity argon with a gas flow rate controlled at 8-12L / min; in step S8, a segmented symmetrical welding method is adopted, and after the segment is completed, the entire weld seam is continuously repaired by welding; in step S9, the post-weld treatment step, the heating gun maintains the same spacing and movement method as the preheating, and the continuous heat preservation time is not less than 15min, after which it is naturally cooled to room temperature by the constant temperature welding chamber, and sudden cooling by air is prohibited; the raw material of the plate is automotive aluminum alloy thin plate or high-strength steel cold-rolled thin plate, and the constant temperature welding chamber is a closed heat-insulated structure, equipped with a circulating air distribution device to ensure that the temperature deviation of the entire area does not exceed ±1℃.

[0044] The workflow is as follows:

[0045] In the S1 raw material preparation stage, first select 5052 aluminum alloy thin-walled sheets that meet automotive lightweighting standards, and verify the sheet thickness, flatness, and material specifications. At the same time, test the sealed, insulated constant temperature welding chamber, pulse argon arc welding machine, and industrial constant temperature heating gun in advance. Check whether the constant temperature welding room temperature control system, circulating air distribution device, welding machine circuit and gas circuit, and heating gun temperature control air outlet system are normal. Prepare auxiliary consumables and tooling such as fine sandpaper, steel wool, anhydrous ethanol, flexible clamping fixtures, and high-purity argon gas to ensure that all equipment and materials are in good condition and meet the conditions for continuous welding operations.

[0046] In the S2 raw material transfer stage, the aluminum alloy thin-walled sheet to be welded is smoothly transported to the placement platform inside the constant temperature welding chamber; then the pulse argon arc welding machine that has been debugged is moved into the constant temperature welding chamber as a whole, and the welding machine power supply and argon gas pipeline are connected to ensure that the pipeline is neatly arranged without bends or leaks, so as to make preliminary arrangements for subsequent constant temperature operations and welding operations.

[0047] In the S3 raw material cleaning stage, 800-grit sandpaper and steel wool are used to finely grind the area on both sides of the weld seam of the two thin-walled plates. The grinding range is strictly controlled to 20mm on each side of the weld seam. The plate surface oxide scale, rust, stamping oil stains and processing residue burrs are thoroughly removed. After grinding, a dust-free cotton cloth soaked in anhydrous ethanol is used to repeatedly wipe the weld seam area and surrounding plate surface. After wiping, let it stand naturally for 8 minutes. Only after the surface ethanol is completely dry and there are no residual water stains or oil stains can it proceed to the next process to avoid impurities causing weld slag inclusions and porosity defects.

[0048] In the S4 stage of fixing the sheet material, a special clamping device with a built-in flexible silicone anti-slip pad is used to position and clamp the thin-walled sheet material, ensuring precise alignment of the sheet material to be joined. The clamping force is adjusted to set the clamping pressure to 0.4MPa, allowing the silicone pad to make soft contact with the sheet material. This ensures that there is no displacement or misalignment of the sheet material during welding, and also prevents indentations and dents caused by rigid clamping on the surface of the thin-walled sheet material. After the sheet material is fixed, the welding torch head of the welding equipment is moved to the side of the weld start position to prepare for welding.

[0049] During the temperature adjustment phase of the S5 constant temperature welding chamber, the constant temperature welding chamber temperature control system and internal circulating air distribution device are activated to precisely adjust and maintain the indoor temperature at 7℃. The circulating air distribution device enables slow air circulation in the chamber, ensuring uniform temperature in all areas of the welding chamber, with the overall temperature deviation controlled within ±1℃. After temperature adjustment, the chamber is kept at the desired temperature for 10 minutes to confirm that there are no fluctuations in the indoor temperature or uneven heating / cooling in any localized areas. This avoids interference from external ambient temperature fluctuations on the welding of thin-walled plates and establishes a stable low-temperature constant temperature welding environment.

[0050] In the preheating stage of the S6 sheet material, the heating gun is turned on and the heating temperature is set to a constant 450℃. After the temperature of the air outlet of the gun head stabilizes, the distance between the heating gun and the surface of the aluminum alloy sheet is controlled to be 100mm. The heating gun is moved back and forth, up and down, horizontally and vertically at a uniform speed of 12cm / s to preheat the entire thin-walled sheet material. The preheating time is controlled to be 4 minutes. There is no local stop or close-range direct heating throughout the process to ensure that the overall temperature rise of the sheet material is uniform, eliminate the internal temperature gradient of the sheet material, and avoid stress deformation caused by local temperature difference during subsequent welding. This lays the temperature foundation for low-temperature welding.

[0051] S7 In the stage of adjusting the welding parameters of the welding equipment, the welding temperature range of the pulse argon arc welding machine is adjusted to 300℃, which is within the low temperature welding range of 200℃-500℃ defined by this invention; the welding current is set to 90A, the welding travel speed is set to 25cm / min, the shielding gas is selected as high-purity argon, and the argon flow rate is adjusted to 10L / min. After all parameters are set, a no-load test run is performed for 30s to confirm that the welding machine has stable arc ignition and stable gas flow output.

[0052] In the S8 welding stage, a segmented symmetrical welding method is adopted. The standard welding length of a single segment is set at 50mm. After each segment is completed, there is a 25-second pause to allow the weld seam to cool down slightly and stabilize before proceeding to the next segment. The welding is completed segment by segment in a symmetrical order from the middle to both ends. After all segments are welded, a continuous repair welding is performed along the entire weld seam to reshape it. The heat input is controlled to be uniform throughout the process to avoid heat concentration in a single welding process, which could cause deformation of the thin plate. This ensures that the weld seam is full, without undercut, and without any incomplete or missing welds.

[0053] In the S9 post-weld treatment stage, the heating gun is not removed immediately after welding. The heating gun is kept at a constant temperature of 450℃, with a spacing of 100mm and a cross-sweeping movement. The entire thin-walled plate is continuously heated for 18 minutes after welding. After the heating is completed, the heating gun is turned off and the constant temperature welding chamber is kept sealed. The plate is allowed to cool down to room temperature naturally and slowly with the indoor environment. It is strictly forbidden to open the chamber door for ventilation or use a fan for cooling. The continuous heating and slow cooling after welding releases the welding internal stress, inhibits the formation of cold cracks in the weld, and stabilizes the microstructure and properties of the welded joint.

[0054] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A low-temperature welding method for thin-walled plates used in lightweight automotive components, characterized in that, The welding method includes the following steps: S1: Raw material preparation, take the raw material of the plate, prepare the constant temperature welding chamber and welding equipment, heating gun; S2: Raw material transfer, placing the sheet metal raw materials and welding equipment in a constant temperature welding chamber; S3: Cleaning of sheet material, grinding the welding area of ​​the sheet material to remove dirt, oxide scale, etc.; S4: Fixing the sheet material: Use a clamping device to clamp and fix the sheet material, and move the welding equipment next to the sheet material to prepare for welding. S5: Temperature adjustment of the constant temperature welding chamber. Adjust the temperature of the constant temperature welding chamber to greater than or equal to 0℃ and maintain a constant temperature. S6: Preheating of board material: The board material is preheated using a heating gun. The board material is heated as a whole by moving the heating gun back and forth and up and down to preheat the board material comprehensively. S7: Adjust the welding parameters of the welding equipment to set the welding temperature to 200℃-500℃; S8: Welding, using welding equipment to weld preheated sheet metal raw materials; S9: Post-weld treatment: After the sheet material is welded, it is continuously heated as a whole using a heating gun.

2. The low-temperature welding method for thin-walled plates used in lightweight automotive components according to claim 1, characterized in that, The temperature of the constant temperature welding chamber in S5 is 7℃.

3. The low-temperature welding method for thin-walled plates used in lightweight automotive components according to claim 1, characterized in that, The heating temperature of the heating guns in S6 and S9 is 450℃.

4. The low-temperature welding method for thin-walled plates used in lightweight automotive components according to claim 1, characterized in that, In the S3 sheet material cleaning process, fine sandpaper and steel wool are used to repeatedly polish the welding joint area of ​​the sheet material. After polishing, the surface is wiped with anhydrous ethanol and left to air dry to remove residual oil and dust.

5. The low-temperature welding method for thin-walled plates used in lightweight automotive components according to claim 1, characterized in that, In the S4 sheet material fixing step, the clamping device uses flexible silicone anti-slip pads to contact the sheet surface, avoiding indentations and deformation caused by rigid clamping of the thin-walled sheet material.

6. The low-temperature welding method for thin-walled plates used in lightweight automotive components according to claim 1, characterized in that, In the preheating step of S6 board material, the distance between the heating gun and the board surface is maintained at 80-120mm, the moving speed is 10-15cm / s, and the horizontal and vertical cross-sweeping method is used for comprehensive heating. The preheating time is controlled at 3-5min to ensure that the overall temperature of the board material is uniform.

7. The low-temperature welding method for thin-walled plates used in lightweight automotive components according to claim 1, characterized in that, The welding equipment used in S7 is a pulsed argon arc welding machine. The welding current is set to 60-110A, the welding travel speed is 20-30cm / min, and the shielding gas is high-purity argon with a gas flow rate controlled at 8-12L / min.

8. The low-temperature welding method for thin-walled plates used in lightweight automotive components according to claim 1, characterized in that, In the S8 welding process, a segmented symmetrical welding method is adopted. After the segments are completed, the entire weld seam is continuously repaired.

9. The low-temperature welding method for thin-walled plates used in lightweight automotive components according to claim 1, characterized in that, In the S9 post-weld treatment steps, the heating gun should maintain the same spacing and movement as the preheating gun, and the heating time should be kept at a constant temperature for no less than 15 minutes. After that, the temperature should be allowed to drop naturally to room temperature in the constant temperature welding chamber. Sudden cooling by air is prohibited.

10. The low-temperature welding method for thin-walled plates used in lightweight automotive components according to claim 1, characterized in that, The raw material for the sheet is aluminum alloy sheet for automobiles or cold-rolled sheet of high-strength steel. The constant temperature welding chamber is a closed and heat-insulated structure, and is equipped with a circulating air distribution device to ensure that the temperature deviation throughout the entire area does not exceed ±1℃.

Images