Laser weld joint welding system and method based on diffuse reflection material preheating

Abstract

The invention discloses a laser weld joint welding system based on diffuse reflection material preheating, and belongs to the technical field of laser welding. The system comprises a preheating welding system and a welding workbench, the preheating welding system is composed of a welding laser generator and a preheating device, the welding laser generator is provided with a first laser welding head and a second laser welding head which are used for main welding and auxiliary preheating respectively, and the focusing and working distance can be accurately adjusted; proper sizes of welding light spots and preheating light spots are ensured; the preheating device effectively reflects laser beams and evenly distributes preheating light spots to a welding area through a mirror reflection plate and a U-shaped diffuse reflection light reflection baffle. The system further has an intelligent control function, the laser light source power, the welding parameters and the angle and position of the preheating device can be automatically adjusted according to feedback of the temperature sensor, the laser power and the preheating parameters are automatically adjusted, and the safety of the welding process and the consistency of welding seams are guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of laser welding, and in particular to a laser welding system and method based on preheating of diffuse reflection materials. Background Art

[0002] In the field of laser welding, the quality of the weld is directly related to the overall performance and reliability of the product. The size of the weld is small, which will lead to a large temperature difference between the weld area and the surrounding materials, causing thermal stress and deformation during the welding stage; when the welding is completed, the surrounding materials are at a low temperature, resulting in too fast cooling rate, causing changes in the microstructure of some materials. For materials with low absorptivity or high reflectivity, under laser irradiation, due to surface reflection, the laser energy cannot be effectively concentrated in the weld area, further affecting the welding speed and weld quality.

[0003] In order to solve this problem, researchers began to explore the application of preheating technology in laser welding. Preheating can not only improve the material's absorption rate of laser energy, but also improve the microstructure and mechanical properties of the weld by reducing thermal stress during welding. However, traditional preheating methods often have problems such as uneven surface temperature of the material in the early stage of welding, large energy loss, and easy cracking, which makes it difficult to meet the needs of high-precision and high-efficiency welding. Summary of the invention

[0004] The purpose of the present invention is to provide a laser welding system and method based on diffuse reflection material preheating to solve the problems of uneven material surface temperature, large energy loss and easy cracking in the traditional preheating method in the above-mentioned background technology at the initial stage of welding.

[0005] To achieve the above object, the present invention provides the following technical solutions: A laser seam welding system based on diffuse reflection material preheating, comprising a preheating welding system and a welding workbench, wherein the preheating welding system is composed of a welding laser generator and a preheating device; The welding laser generator includes a first laser welding head, a second laser welding head, a laser light source and a temperature sensor. The first laser welding head is used to adjust the focal length and working distance during welding to obtain a welding spot of a suitable size. The second laser welding head is used to adjust the focal length and working distance during preheating to obtain a preheating spot of a suitable size. The temperature sensor is installed near the welding area to monitor the welding temperature and preheating temperature in real time to ensure that the temperature reaches the set value. The preheating device comprises a specular reflective plate and a U-shaped diffuse reflective baffle, wherein the specular reflective plate is prepared by vacuum deposition of a multi-layer dielectric high reflective film on fused quartz; the interior of the U-shaped shell of the U-shaped diffuse reflective baffle is a diffuse reflective material, wherein the diffuse reflective material has high reflectivity and good thermal stability, and the diffuse reflective material is composed of a substrate, an adhesive layer and a double-layer coating; to ensure a high reflectivity and a low thermal resistance, the laser beam can be effectively reflected and the preheating spot can be evenly distributed to the welding area; As a preferred technical solution of the present invention, the reflectivity of the mirror reflection plate is 99.10%~99.40%; the porosity of the diffuse reflection material is 7~9%, and the reflectivity is 88~92%; the multilayer dielectric high reflection film is a composite film of TiO2 and SiO2; the base material is one or more of copper, aluminum, stainless steel 304, brass, and galvanized steel; the double-layer coating is a dense layer and a functional layer.

[0006] As a preferred technical solution of the present invention, the laser light source adjusts the preheating temperature through different powers and different wavelengths.

[0007] Furthermore, the wavelength of the laser light source is 800-1100 nm, the welding power is 1-4 kW, the preheating power is 0.1-0.8 kW; and the preheating temperature is 15-40% of the welding temperature.

[0008] As a preferred technical solution of the present invention, the preheating spot is located 5 to 10 mm in front of the welding spot and has a diameter 2 to 5 times the width of the weld.

[0009] As a preferred technical solution of the present invention, the preheating welding system also includes a control unit, which is electrically connected to the welding laser generator and the preheating device. The control unit can automatically adjust the laser light source power, welding parameters and the angle and position of the preheating device according to feedback from the temperature sensor to achieve intelligent control.

[0010] In the above-mentioned laser welding system based on preheating of diffuse reflection material, the preparation method of the diffuse reflection material is as follows: S01, substrate pretreatment: after cleaning with ethanol, sandblasting; S02. Preparation of bonding layer and double-layer coating: Adopt normal pressure plasma spraying method, use Ni5Al powder with a particle size of 45~90μm to spray the bonding layer, use aluminum oxide powder with a particle size of 20~45μm to spray the 400~500μm dense layer, and use aluminum oxide powder with a particle size of 20~90μm to spray the 80~100μm functional layer.

[0011] The welding method of the laser seam welding system based on diffuse reflection material preheating described above comprises the following steps: S1. System initialization and parameter setting Placing the workpiece to be welded on the welding workbench, setting the preheating temperature, and adjusting the focal length and working distance parameters of the first laser welding head and the second laser welding head; Determining laser power parameters and welding speed parameters of the first laser welding head and the second laser welding head according to the material, thickness and expected weld width of the workpiece to be welded; S2, Intelligent preheating and temperature monitoring Start the laser transmitter, use the second laser welding head to emit a preheating laser beam, the preheating laser beam is first reflected by the mirror reflection plate to the U-shaped diffuse reflection reflective baffle, and then diffusely reflected by the U-shaped diffuse reflection reflective baffle to the preheating area to be welded; the control center monitors the preheating process in real time, and automatically adjusts the laser power of the second laser welding head and the angle and position of the preheating device according to the feedback of the temperature sensor; ensure that the preheating area to be welded is evenly preheated to the set preheating temperature; The second laser welding head preheats the weld along a predetermined welding path, while the temperature sensor monitors the preheating temperature at the weld in real time to ensure that the safe temperature threshold is reached without cracks. When the weld reaches the set preheating temperature, proceed to step S3; S3. Precision welding and dynamic control After the welding area reaches the set preheating temperature, the first laser welding head performs fine welding along the preheating area path at the set welding speed, and the welding laser beam is reflected by the workpiece to be welded to the U-shaped diffuse reflection reflective baffle and then diffusely reflected to the preheating area to be welded, so as to reduce the power of the second laser welding head; During the welding process, the temperature sensor continuously monitors the weld temperature to ensure the welding quality; the control center intelligently adjusts the welding parameters based on the real-time feedback from the temperature sensor to cope with possible welding changes and form a uniform, dense and high-quality weld; S4. Post-welding treatment and quality control After welding is completed, turn off the laser transmitter immediately to stop the welding process; perform professional cooling treatment on the welded parts to prevent deformation or cracks caused by thermal stress; This is followed by a thorough cleaning to remove welding residues; Finally, strict quality inspection is carried out, including weld appearance inspection and mechanical property testing, to ensure that the welded parts meet all design requirements and quality standards.

[0012] In summary, compared with the prior art, the present invention has the following beneficial effects: 1. By precisely controlling the preheating temperature and combining the unique properties of diffuse reflective materials, the heat is evenly distributed throughout the entire area to be welded, avoiding the problems of excessive temperature gradient and uneven preheating that may occur in traditional preheating methods, thereby improving the preheating efficiency and ensuring the temperature consistency of the weld before welding, creating favorable conditions for the subsequent fine welding process.

[0013] 2. The high-reflectivity diffuse reflective material (reflectivity is 88%~92%, porosity is 7%~9%) contained in the U-shaped diffuse reflective baffle ensures the maximum recovery and reuse of preheating and welding laser energy; the welding laser beam is diffusely reflected, which not only enhances the preheating effect, but also reduces the requirement for the preheating power of the second laser welding head, saving energy.

[0014] 3. The integrated temperature sensor cooperates with the intelligent control unit to automatically adjust the laser power, focal length, working distance and even the position and angle of the preheating device according to the real-time feedback data. This intelligent control system ensures the optimal setting of welding parameters to cope with possible welding changes, thereby ensuring the uniformity, density and high quality of the weld. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a flow chart of the welding method of the present invention; Figure 2 It is a structural schematic diagram of the laser welding system based on diffuse reflection material preheating of the present invention; Figure 3 A method for preparing the diffuse reflection material of the present invention; In the figure: 1-workpiece to be welded, 2-mirror reflection plate, 3-U-shaped diffuse reflection baffle, 41-first laser welding head, 42-second laser welding head. DETAILED DESCRIPTION

[0016] The specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. It should be understood that the specific embodiments given here are only used to illustrate and explain the present invention, and cannot be used to limit the present invention.

[0017] It should be noted that many specific details are set forth in the following description to facilitate a full understanding of the present invention. However, the present invention may also have other implementation modes. Therefore, the protection scope of the present invention is not limited to the specific embodiments disclosed below.

[0018] Combined with Figure 1 It can be seen that a laser seam welding system based on diffuse reflection material preheating includes a preheating welding system and a welding workbench, wherein the preheating welding system is composed of a welding laser generator and a preheating device; The welding laser generator includes a first laser welding head 41, a second laser welding head 42, a laser light source and a temperature sensor. The first laser welding head 41 is used to adjust the focal length and working distance during welding to obtain a welding spot of a suitable size. The second laser welding head 42 is used to adjust the focal length and working distance during preheating to obtain a preheating spot of a suitable size. The temperature sensor is installed near the welding area to monitor the welding temperature and preheating temperature in real time to ensure that the temperature reaches the set value. The preheating device comprises a specular reflective plate 2 and a U-shaped diffuse reflective baffle 3, wherein the specular reflective plate 2 is prepared by vacuum deposition of a multi-layer dielectric high reflective film on fused quartz; the interior of the U-shaped shell of the U-shaped diffuse reflective baffle 3 is a diffuse reflective material, and the diffuse reflective material is composed of a substrate with high reflectivity and good thermal stability, a bonding layer and a double-layer coating; to ensure high reflectivity and low thermal resistance, it can effectively reflect the laser beam and evenly distribute the preheating spot to the welding area; As a preferred embodiment of the present invention, the reflectivity of the mirror reflection plate 2 is 99.10%~99.40%; the porosity of the diffuse reflection material is 7~9%, and the reflectivity is 88~92%; the multilayer dielectric high reflection film is a composite film of TiO2 and SiO2; the base material is one or more of copper, aluminum, stainless steel 304, brass, and galvanized steel; the double-layer coating is a dense layer and a functional layer.

[0019] In this specific embodiment, the reflectivity of the mirror reflection plate 2 is 99.30%; the porosity of the diffuse reflection material is 8% and the reflectivity is 91%; and the base material is galvanized steel.

[0020] As a preferred embodiment of the present invention, the laser light source adjusts the preheating temperature through different powers and different wavelengths.

[0021] Furthermore, the wavelength of the laser light source is 800-1100 nm, the welding power is 1-4 kW, the preheating power is 0.1-0.8 kW; and the preheating temperature is 15-40% of the welding temperature.

[0022] In this specific embodiment, the wavelength of the laser light source is 1064 nm, the welding power is 3 kW, the preheating power is 0.2 kW; and the preheating temperature is 18% of the welding temperature.

[0023] As a preferred embodiment of the present invention, the preheating spot is located 5-10 mm in front of the welding spot and has a diameter 2-5 times the width of the weld.

[0024] In this specific embodiment, the preheating spot is located 10 mm in front of the welding spot and has a diameter that is 4 times the width of the weld.

[0025] As a preferred embodiment of the present invention, the preheating welding system also includes a control unit, which is electrically connected to the welding laser generator and the preheating device. The control unit can automatically adjust the laser light source power, welding parameters and the angle and position of the preheating device according to feedback from the temperature sensor to achieve intelligent control.

[0026] Combined with Figure 3 It can be seen that the preparation method of the diffuse reflection material is as follows: S01, substrate pretreatment: after cleaning with ethanol, sandblasting; S02. Preparation of bonding layer and double-layer coating: Adopt normal pressure plasma spraying method, use Ni5Al powder with a particle size of 45~90μm to spray the bonding layer, use alumina powder with a particle size of 20~45μm to spray the 400~500μm dense layer, and use alumina powder with a particle size of 20~90μm to spray the 80~100μm functional layer.

[0027] In this specific embodiment, Ni5Al powder with a particle size of 80 μm is used to spray the bonding layer, aluminum oxide powder with a particle size of 35 μm is used to spray the 450 μm dense layer, and aluminum oxide powder with a particle size of 65 μm is used to spray the 95 μm functional layer.

[0028] Combined with Figure 2 It can be seen that the welding method of the laser welding system based on diffuse reflection material preheating described above includes the following steps: S1. System initialization and parameter setting Place the workpiece 1 to be welded on the welding workbench, set the preheating temperature, and adjust the focal length and working distance parameters of the first laser welding head 41 and the second laser welding head 42; Determine the laser power parameters and welding speed parameters of the first laser welding head 41 and the second laser welding head 42 according to the material, thickness and expected weld width of the workpiece 1 to be welded; S2, Intelligent preheating and temperature monitoring Start the laser transmitter, and use the second laser welding head 42 to emit a preheating laser beam, which is first reflected by the mirror reflection plate 2 to the U-shaped diffuse reflection reflective baffle 3, and then diffusely reflected by the U-shaped diffuse reflection reflective baffle 3 to the preheating area to be welded; the control center monitors the preheating process in real time, and automatically adjusts the laser power of the second laser welding head 42 and the angle and position of the preheating device according to the feedback of the temperature sensor; ensure that the preheating area to be welded is evenly preheated to the set preheating temperature; The second laser welding head 42 preheats the weld along a predetermined welding path, and the temperature sensor monitors the preheating temperature at the weld in real time to ensure that a safe temperature threshold is reached without cracks. When the weld reaches the set preheating temperature, proceed to step S3; S3. Precision welding and dynamic control After the welding area reaches the set preheating temperature, the first laser welding head 41 performs fine welding along the preheating area path at the set welding speed, and the welding laser beam is reflected by the workpiece 1 to be welded to the U-shaped diffuse reflection reflective baffle 3 and then diffusely reflected to the preheating area to be welded, so as to reduce the power of the second laser welding head 42; During the welding process, the temperature sensor continuously monitors the weld temperature to ensure the welding quality; the control center intelligently adjusts the welding parameters based on the real-time feedback from the temperature sensor to cope with possible welding changes and form a uniform, dense and high-quality weld; S4. Post-welding treatment and quality control After welding is completed, turn off the laser transmitter immediately to stop the welding process; perform professional cooling treatment on the welded parts to prevent deformation or cracks caused by thermal stress; This is followed by a thorough cleaning to remove welding residues; Finally, strict quality inspection is carried out, including weld appearance inspection and mechanical property testing, to ensure that the welded parts meet all design requirements and quality standards.

[0029] Working principle: The laser beam generated by the laser welding generator is used to adjust the focal length and working distance by the second laser welding head 42 to form a preheating spot. The preheating laser beam is reflected by the mirror reflection plate 2 to the U-shaped diffuse reflection reflective baffle 3, and then the laser beam is evenly reflected to the welding area by the diffuse reflection material inside the baffle, so as to achieve uniform preheating of the material surface. The diffuse reflection material is composed of a substrate with high reflectivity and good thermal stability, a bonding layer and a double-layer coating, which ensures high reflectivity and low thermal resistance. During the preheating process, the temperature sensor monitors the temperature of the welding area in real time, and the control unit automatically adjusts the laser power and the angle and position of the preheating device according to the feedback to ensure that the preheating temperature is uniform and reaches the set value. After the preheating is completed, the first laser welding head 41 performs precise welding along the path of the preheating area. At the same time, the temperature sensor continuously monitors the weld temperature, and the control center intelligently adjusts the welding parameters to ensure the welding quality.

[0030] The embodiments of the present invention are described in detail above with reference to the accompanying drawings, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions and variations of these embodiments are made without departing from the principles and spirit of the present invention, and still fall within the scope of protection of the present invention.

Claims

1. A laser seam welding system based on diffuse reflection material preheating, comprising a preheating welding system and a welding workbench, characterized in that: The preheating welding system is composed of a welding laser generator and a preheating device; The welding laser generator includes a first laser welding head, a second laser welding head, a laser light source and a temperature sensor. The first laser welding head is used to adjust the focal length and working distance during welding to obtain a welding spot of a suitable size. The second laser welding head is used to adjust the focal length during preheating to pre-adjust the preheating spot size and the working distance. The temperature sensor is installed near the welding area to monitor the welding temperature and preheating temperature in real time. The preheating device includes a mirror reflection plate and a U-shaped diffuse reflection reflective baffle, the mirror reflection plate is prepared by vacuum deposition of a multi-layer dielectric high-reflection film on molten quartz; the interior of the U-shaped shell of the U-shaped diffuse reflection reflective baffle is a diffuse reflection material, the diffuse reflection material is composed of a substrate, a bonding layer and a double-layer coating, the material of the substrate is one or more of copper, aluminum, stainless steel 304, brass, and galvanized steel; the double-layer coating is a dense layer and a functional layer.

2. The laser seam welding system based on diffuse reflection material preheating according to claim 1 is characterized in that: The reflectivity of the mirror reflection plate is 99.10% to 99.40%; the porosity of the diffuse reflection material is 7 to 9% and the reflectivity is 88 to 92%; the multi-layer dielectric high-reflection film is a composite film of TiO2 and SiO2.

3. The laser seam welding system based on diffuse reflection material preheating according to claim 1 is characterized in that: The laser light source adjusts the preheating temperature through different powers and different wavelengths; and the preheating spot size is further adjusted by using U-shaped shells of different sizes and shapes.

4. The laser seam welding system based on diffuse reflection material preheating according to claim 3 is characterized in that: The wavelength of the laser light source is 800-1100 nm, the welding power is 1-4 kW, the preheating power is 0.1-0.8 kW; and the preheating temperature is 15-40% of the welding temperature.

5. The laser seam welding system based on diffuse reflection material preheating according to claim 1 is characterized in that: The preheating spot is located 5 to 10 mm in front of the welding spot, and its diameter is 2 to 5 times the width of the weld.

6. The laser seam welding system based on diffuse reflection material preheating according to claim 1 is characterized in that: The preheating welding system also includes a control unit, which is electrically connected to the welding laser generator and the preheating device. The control unit can automatically adjust the laser light source power, welding parameters and the angle and position of the preheating device according to feedback from the temperature sensor.

7. The laser welding system based on diffuse reflection material preheating according to any one of claims 1 to 6, characterized in that: The preparation method of the diffuse reflection material is as follows: S01, substrate pretreatment: after cleaning with ethanol, sandblasting; S02. Preparation of bonding layer and double-layer coating: Adopt normal pressure plasma spraying method, use Ni5Al powder with a particle size of 45~90μm to spray the bonding layer, use alumina powder with a particle size of 20~45μm to spray the 400~500μm dense layer, and use alumina powder with a particle size of 20~90μm to spray the 80~100μm functional layer.

8. The welding method of the laser weld system based on diffuse reflection material preheating according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1. System initialization and parameter setting Placing the workpiece to be welded on the welding workbench, setting the preheating temperature, and adjusting the focal length and working distance parameters of the first laser welding head and the second laser welding head; Determining laser power parameters and welding speed parameters of the first laser welding head and the second laser welding head according to the material, thickness and expected weld width of the workpiece to be welded; S2, Intelligent preheating and temperature monitoring The laser transmitter is started, and a preheating laser beam is emitted by a second laser welding head. The preheating laser beam is first reflected by a mirror reflection plate to a U-shaped diffuse reflection baffle, and then diffusely reflected by the U-shaped diffuse reflection baffle to a preheating area to be welded. The control center monitors the preheating process in real time, and automatically adjusts the laser power of the second laser welding head and the angle and position of the preheating device according to feedback from the temperature sensor. The second laser welding head preheats the weld along a predetermined welding path, and the temperature sensor monitors the preheating temperature at the weld in real time; When the weld reaches the set preheating temperature, proceed to step S3; S3. Precision welding and dynamic control After the welding area reaches the set preheating temperature, the first laser welding head performs fine welding along the preheating area path at the set welding speed, and the welding laser beam is reflected by the workpiece to be welded to the U-shaped diffuse reflection reflective baffle and then diffusely reflected to the preheating area to be welded, so as to reduce the power of the second laser welding head; During the welding process, the temperature sensor continuously monitors the weld temperature; the control center intelligently adjusts the welding parameters based on the real-time feedback from the temperature sensor; S4. Post-welding treatment and quality control After welding is completed, turn off the laser transmitter immediately to stop the welding process; Provide professional cooling treatment for welded parts; This is followed by a thorough cleaning to remove welding residues; Finally, strict quality inspection is carried out, including weld appearance inspection and mechanical properties testing.

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