Laser welding system and method based on diffuse reflection material preheating

Abstract

The invention discloses a laser weld system based on diffuse reflection material preheating, belonging to the field of laser welding technology; 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, wherein the welding laser generator has a first laser welding head and a second laser welding head, which are respectively used for main welding and auxiliary preheating, and can accurately adjust the focus and working distance to ensure the appropriate size of the welding spot and the preheating spot; the preheating device utilizes a mirror reflection plate and a U-shaped diffuse reflection reflective baffle to effectively reflect the laser beam and evenly distribute the preheating spot to the welding area; the system also has an intelligent control function, which can automatically adjust the laser light source power, welding parameters and the angle and position of the preheating device according to the feedback of the temperature sensor, realize automatic adjustment of the laser power and preheating parameters, and ensure the safety of the welding process and the consistency of the weld.

Description

Technical Field

[0001] This invention relates to the field of laser welding technology, and in particular to a laser weld system and method based on preheating with diffuse reflection materials. Background Art

[0002] In the field of laser welding, weld quality directly affects the overall performance and reliability of products. Conventional laser spot size...

[0003] The small size of the weld seam leads to a large temperature difference between the weld area and the surrounding material, resulting in thermal stress and deformation during the welding process. Upon completion of welding, the low temperature of the surrounding material causes a rapid cooling rate, altering the microstructure of some materials. For materials with low absorptivity or high reflectivity, surface reflection under laser irradiation prevents the laser energy from being effectively concentrated in the weld area, further affecting welding speed and weld quality.

[0004] To address this issue, researchers began exploring the application of preheating technology in laser welding. Preheating not only increases the material's absorption rate of laser energy but also improves the microstructure and mechanical properties of the weld by reducing thermal stress during the welding process. However, traditional preheating methods often suffer from uneven material surface temperature, significant energy loss, and susceptibility to cracking in the initial stages of welding, making it difficult to meet the demands of high-precision and high-efficiency welding. Summary of the Invention

[0005] The purpose of this invention is to provide a laser welding system and method based on preheating of diffuse reflection materials, so as to solve the problems of uneven material surface temperature, large energy loss and easy cracking in the traditional preheating method in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A laser welding system based on preheating of diffuse reflection material includes a preheating welding system and a welding worktable, wherein the preheating welding system consists of a welding laser generator and a preheating device;

[0008] The welding laser generator includes a first laser welding head, a second laser welding head, a laser 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 appropriate size. The second laser welding head is used to adjust the focal length and working distance during preheating to obtain a preheating spot of appropriate size. The temperature sensor is installed near the welding area to monitor the welding temperature and preheating temperature in real time, ensuring that the temperature reaches the set value.

[0009] The preheating device includes a mirror reflector and a U-shaped diffuse reflective baffle. The mirror reflector is prepared by vacuum deposition of a multilayer dielectric high-reflectivity film onto fused silica. The interior of the U-shaped diffuse reflective baffle is made of a diffuse reflective material with high reflectivity and good thermal stability. The diffuse reflective material consists of a substrate, an adhesive layer, and a double-layer coating. This ensures high reflectivity and low thermal resistance, effectively reflecting the laser beam and uniformly distributing the preheating spot to the welding area.

[0010] As a preferred embodiment of the present invention, the reflectivity of the mirror reflector is 99.10%~99.40%; the porosity of the diffuse reflective material is 7~9% and the reflectivity is 88~92%; the multilayer dielectric high reflective film is a composite film of TiO2 and SiO2; the substrate material is one or more of copper, aluminum, 304 stainless steel, brass, and galvanized steel; and the double coating consists of a dense layer and a functional layer.

[0011] As a preferred embodiment of the present invention, the laser light source adjusts the preheating temperature by using different powers and wavelengths.

[0012] 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.

[0013] As a preferred embodiment of the present invention, the preheating spot is located 5-10 mm in front of the welding spot, and its diameter is 2-5 times the width of the weld.

[0014] As a preferred embodiment of the present invention, the preheating welding system further 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 source power, welding parameters, and the angle and position of the preheating device according to the feedback of the temperature sensor, thereby achieving intelligent control.

[0015] The laser welding system based on diffuse reflection material preheating described above, wherein the diffuse reflection material is prepared as follows:

[0016] S01. Substrate pretreatment: After cleaning with ethanol, sandblasting is performed.

[0017] S02. Preparation of the adhesive layer and double coating: The adhesive layer was prepared by atmospheric pressure plasma spraying using Ni5Al powder with a particle size of 45~90μm, the dense layer was prepared by alumina powder with a particle size of 20~45μm, and the functional layer was prepared by alumina powder with a particle size of 20~90μm.

[0018] The welding method of the laser weld seam welding system based on diffuse reflection material preheating described above includes the following steps:

[0019] S1. System Initialization and Parameter Setting

[0020] The workpiece to be welded is placed on the welding worktable, and the preheating temperature is set, and the focal length and working distance parameters of the first laser welding head and the second laser welding head are adjusted.

[0021] Based on the material, thickness, and expected weld width of the workpiece to be welded, determine the laser power parameters and welding speed parameters of the first laser welding head and the second laser welding head;

[0022] S2, Intelligent Preheating and Temperature Monitoring

[0023] The laser emitter is activated, and a preheating laser beam is emitted from the second laser welding head. The preheating laser beam is first reflected by a mirror reflector to a U-shaped diffuse reflector baffle, and then diffusely reflected by the U-shaped diffuse reflector baffle to the area to be preheated for welding. 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 based on feedback from the temperature sensor to ensure that the area to be preheated is uniformly preheated to the set preheating temperature.

[0024] The second laser welding head preheats the weld along a predetermined welding path, while a temperature sensor monitors the preheating temperature at the weld in real time to ensure that a safe temperature threshold without crack formation is reached.

[0025] When the weld reaches the set preheating temperature, proceed to step S3;

[0026] S3, Precision Welding and Dynamic Control

[0027] 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. The welding laser beam is reflected by the workpiece to be welded to the U-shaped diffuse reflection baffle and then diffusely reflected back to the preheated welding area to reduce the power of the second laser welding head.

[0028] During the welding process, temperature sensors continuously monitor the weld temperature to ensure welding quality; the control center intelligently adjusts welding parameters based on real-time feedback from the temperature sensors to cope with possible welding changes and form a uniform, dense, and high-quality weld.

[0029] S4. Post-welding treatment and quality control

[0030] After welding is completed, immediately turn off the laser emitter and stop the welding process; perform professional cooling treatment on the welded parts to prevent deformation or cracks caused by thermal stress.

[0031] Then a thorough cleaning is performed to remove welding residue;

[0032] Finally, rigorous quality inspections are conducted, including weld appearance inspection and mechanical property testing, to ensure that the welded parts meet all design requirements and quality standards.

[0033] In summary, compared with the prior art, the beneficial effects of the present invention are as follows:

[0034] 1. By precisely controlling the preheating temperature and combining it with the unique properties of diffuse reflective materials, heat is evenly distributed throughout the area to be welded, avoiding the problems of excessive temperature gradient and uneven preheating that may occur in traditional preheating methods. This improves preheating efficiency, ensures the temperature consistency of the weld before welding, and creates favorable conditions for the subsequent fine welding process.

[0035] 2. The U-shaped diffuse reflective baffle contains a high-reflectivity diffuse reflective material (reflectivity of 88%~92% and porosity of 7%~9%), which 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 preheating power requirements of the second laser welding head, saving energy.

[0036] 3. The integrated temperature sensor works in conjunction 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 based on 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. Attached Figure Description

[0037] Figure 1 This is a flowchart of the welding method of the present invention;

[0038] Figure 2 This is a schematic diagram of the laser weld seam welding system based on diffuse reflection material preheating according to the present invention;

[0039] Figure 3 This invention relates to a method for preparing diffuse reflective materials;

[0040] In the figure: 1-workpiece to be welded, 2-mirror reflector, 3-U-shaped diffuse reflection baffle, 41-first laser welding head, 42-second laser welding head. Detailed Implementation

[0041] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments given herein are for illustration and explanation only and are not intended to limit the present invention.

[0042] It should be noted that many specific details are set forth in the following description in order to provide a full understanding of the present invention. However, the present invention may have other embodiments, and therefore, the scope of protection of the present invention is not limited to the specific embodiments disclosed below.

[0043] Combined with appendix Figure 1 It is known that a laser weld seam welding system based on preheating of diffuse reflection material includes a preheating welding system and a welding worktable, wherein the preheating welding system consists of a welding laser generator and a preheating device;

[0044] The welding laser generator includes a first laser welding head 41, a second laser welding head 42, a laser 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 appropriate 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 appropriate size. The temperature sensor is installed near the welding area to monitor the welding temperature and preheating temperature in real time, ensuring that the temperature reaches the set value.

[0045] The preheating device includes a mirror reflector 2 and a U-shaped diffuse reflective baffle 3. The mirror reflector 2 is prepared by vacuum deposition of a multilayer dielectric high-reflectivity film onto fused silica. The interior of the U-shaped diffuse reflective baffle 3 is made of a diffuse reflective material, which consists of a substrate with high reflectivity and good thermal stability, an adhesive layer, and a double-layer coating. This ensures high reflectivity and low thermal resistance, effectively reflecting the laser beam and uniformly distributing the preheating spot to the welding area.

[0046] In a preferred embodiment of the present invention, the reflectivity of the mirror reflector 2 is 99.10%~99.40%; the porosity of the diffuse reflective material is 7~9% and the reflectivity is 88~92%; the multilayer dielectric high reflective film is a composite film of TiO2 and SiO2; the substrate material is one or more of copper, aluminum, 304 stainless steel, brass, and galvanized steel; and the double coating layer consists of a dense layer and a functional layer.

[0047] In this specific embodiment, the reflectivity of the mirror reflector 2 is 99.30%; the porosity of the diffuse reflective material is 8% and the reflectivity is 91%; the substrate material is galvanized steel.

[0048] In a preferred embodiment of the present invention, the laser light source adjusts the preheating temperature by using different powers and wavelengths.

[0049] Furthermore, the wavelength of the laser light source is 800~1100nm, 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.

[0050] In this specific embodiment, the wavelength of the laser light source is 1064nm, the welding power is 3 kW, the preheating power is 0.2 kW, and the preheating temperature is 18% of the welding temperature.

[0051] In a preferred embodiment of the present invention, the preheating spot is located 5-10 mm in front of the welding spot, and its diameter is 2 to 5 times the width of the weld.

[0052] In this specific embodiment, the preheating spot is located 10mm directly in front of the welding spot, and its diameter is 4 times the width of the weld.

[0053] In a preferred embodiment of the present invention, the preheating welding system further 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 source power, welding parameters, and the angle and position of the preheating device based on the feedback from the temperature sensor, thereby achieving intelligent control.

[0054] Combined with attachment Figure 3 It can be seen that the preparation method of the diffuse reflective material is as follows:

[0055] S01. Substrate pretreatment: After cleaning with ethanol, sandblasting is performed.

[0056] S02. Preparation of adhesive layer and double coating: The adhesive layer is prepared by atmospheric pressure plasma spraying. Ni5Al powder with a particle size of 45~90μm is used to spray the adhesive layer, alumina powder with a particle size of 20~45μm is used to spray the dense layer of 400~500μm, and alumina powder with a particle size of 20~90μm is used to spray the functional layer of 80~100μm.

[0057] In this specific embodiment, Ni5Al powder with a particle size of 80μm is used to spray the adhesive layer, alumina powder with a particle size of 35μm is used to spray the 450μm dense layer, and alumina powder with a particle size of 65μm is used to spray the 95μm functional layer.

[0058] Combined with attachment Figure 2 It can be seen that the welding method of the laser weld seam welding system based on diffuse reflection material preheating described above includes the following steps:

[0059] S1. System Initialization and Parameter Setting

[0060] Place the workpiece 1 to be welded on the welding worktable, 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;

[0061] Based on the material, thickness, and expected weld width of the workpiece 1 to be welded, determine the laser power parameters and welding speed parameters of the first laser welding head 41 and the second laser welding head 42;

[0062] S2, Intelligent Preheating and Temperature Monitoring

[0063] The laser emitter is activated, and a preheating laser beam is emitted using the second laser welding head 42. The preheating laser beam is first reflected by the mirror reflector 2 to the U-shaped diffuse reflector baffle 3, and then diffusely reflected by the U-shaped diffuse reflector baffle 3 to the area to be preheated for welding. 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 based on the feedback from the temperature sensor to ensure that the area to be preheated for welding is uniformly preheated to the set preheating temperature.

[0064] The second laser welding head 42 preheats the weld along a predetermined welding path, while a temperature sensor monitors the preheating temperature at the weld in real time to ensure that a safe temperature threshold without crack formation is reached.

[0065] When the weld reaches the set preheating temperature, proceed to step S3;

[0066] S3, Precision Welding and Dynamic Control

[0067] 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. The welding laser beam is reflected by the workpiece 1 to be welded to the U-shaped diffuse reflection reflector 3 and then diffusely reflected to the preheated welding area to reduce the power of the second laser welding head 42.

[0068] During the welding process, temperature sensors continuously monitor the weld temperature to ensure welding quality; the control center intelligently adjusts welding parameters based on real-time feedback from the temperature sensors to cope with possible welding changes and form a uniform, dense, and high-quality weld.

[0069] S4. Post-welding treatment and quality control

[0070] After welding is completed, immediately turn off the laser emitter and stop the welding process; perform professional cooling treatment on the welded parts to prevent deformation or cracks caused by thermal stress.

[0071] Then a thorough cleaning is performed to remove welding residue;

[0072] Finally, rigorous quality inspections are conducted, including weld appearance inspection and mechanical property testing, to ensure that the welded parts meet all design requirements and quality standards.

[0073] Mechanism of action:

[0074] The laser beam generated by the laser welding generator is used by the second laser welding head 42 to adjust the focal length and working distance to form a preheating spot. The preheating laser beam is reflected by the mirror reflector 2 to the U-shaped diffuse reflective baffle 3, and then the laser beam is uniformly reflected onto the welding area by the diffuse reflective material inside the baffle, achieving uniform preheating of the material surface. The diffuse reflective material consists of a substrate with high reflectivity and good thermal stability, an adhesive layer, and a double coating layer, ensuring 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 based on the feedback to ensure that the preheating temperature is uniform and reaches the set value. After preheating, the first laser welding head 41 performs precise welding along the path of the preheating area, while the temperature sensor continuously monitors the weld temperature, and the control center intelligently adjusts the welding parameters to ensure welding quality.

[0075] 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. It is apparent to those skilled in the art that various changes, modifications, substitutions, and variations to these embodiments may be made without departing from the principles and spirit of the present invention, and these changes and modifications 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 comprises a specular reflector and a U-shaped diffuse reflective baffle, wherein the specular reflector 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, and the diffuse reflective material is composed of a substrate, a bonding layer and a double-layer coating, and 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; The reflectivity of the mirror reflector is 99.10% to 99.40%; the porosity of the diffuse reflector is 7% to 9% and the reflectivity is 88% to 92%; the multi-layer dielectric high reflective film is a composite film of TiO2 and SiO2; 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; 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.

2. 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.

3. The laser seam welding system based on diffuse reflection material preheating according to claim 1 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.

4. 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.

5. The welding method of the laser weld system based on diffuse reflection material preheating according to any one of claims 1 to 4, 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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