A control method for asymmetric "∞" scanning laser welding of dissimilar materials

Abstract

The present invention belongs to the technical field related to dissimilar material welding, and discloses a control method for asymmetric "∞"-shaped scanning laser dissimilar material welding, which includes the following steps: 1) determining an energy distribution coefficient according to the geometric asymmetry degree of the dissimilar material weld seam; 2) determining an energy distribution control scheme and adjustment parameters according to the energy distribution coefficient of the dissimilar material; 3) adjusting the gap between the dissimilar material welding plates to complete the positioning and clamping of the welding plates; 4) adjusting other welding process parameters to complete the welding process of the dissimilar material. The present invention realizes the efficient adjustment of the gap between the dissimilar material welding plates through a gap adjustment block, and uses a variable-power laser beam and an asymmetric "∞"-shaped scanning path to adjust the energy distribution during the dissimilar material welding process, suppress the formation of geometric asymmetry and porosity defects in the dissimilar material weld seam, improve the forming quality of the dissimilar material weld seam, and meet the control requirements for the weld appearance and joint performance of dissimilar material welding.

Description

Technical Field

[0001] The invention relates to a dissimilar material welding technology, in particular to a control method for asymmetric "∞"-shaped scanning laser dissimilar material welding. Background Art

[0002] In order to meet the demand for comprehensive product performance under complex working conditions, dissimilar material welding joints with multiple material characteristics are widely used in transportation, aerospace, and offshore platforms. Compared with the welding process of the same material, the difference in the performance of dissimilar materials easily leads to welding defects such as geometric asymmetry, cracks, and pores in the weld. The geometric asymmetry and pore defects of the weld will lead to problems such as stress concentration, poor corrosion resistance, and low toughness in the joint, which seriously affect the welding quality of dissimilar materials. At present, the welding methods of dissimilar materials mainly include stir friction welding, arc welding, and laser welding. Among them, stir friction welding has a large restriction on the size of the workpiece, the heat-affected zone of the arc welding weld is large, and the pore defects of the conventional laser welding weld are serious. It is difficult to suppress the formation of geometric asymmetry of the weld of dissimilar materials.

[0003] Scanning laser welding is a new type of laser welding process that periodically changes the movement path of the laser beam by rotating the galvanometer. The scanning laser beam can improve the energy distribution of the molten pool and the dynamic behavior of the small holes in the molten pool, enhance the stability of the welding process, reduce weld porosity and cracks, and improve the forming quality of dissimilar material welds. However, in the currently used scanning laser welding method, the laser beam scanning path is often set to be symmetrical along the welding center line, which makes it difficult to effectively suppress the geometric asymmetry of dissimilar material welds. In addition, in the process of dissimilar material welding, the high-precision adjustment and positioning clamping efficiency of the welding plate gap is low, which seriously affects the welding efficiency of dissimilar materials. It is urgent to propose a high-efficiency control method that can be used in the laser welding process of dissimilar materials. Summary of the invention

[0004] The purpose of the present invention is to solve the above problems and propose a control method for asymmetric "∞" scanning laser welding of dissimilar materials. The variable power laser beam and asymmetric "∞" scanning path are used to adjust the energy distribution in the welding process of dissimilar materials, and to suppress the formation of welding defects such as geometric asymmetry and pores of dissimilar material welds. By using the gap adjustment block and the positioning clamping mechanism in combination, the positioning adjustment time of the dissimilar material welding plate is reduced, and the dissimilar material welding process is completed with high efficiency and high quality.

[0005] The present invention is achieved through the following technical solutions:

[0006] A control method for asymmetric "∞" scanning laser welding of dissimilar materials, which uses a variable power laser beam and an asymmetric "∞" scanning path to adjust the energy distribution in the laser welding process of dissimilar materials, and controls the welding process and weld quality of dissimilar materials. The method is characterized in that it includes the following steps:

[0007] 1) According to the degree of geometric asymmetry of the dissimilar material weld, the energy distribution coefficient is determined, and the cross-sectional geometric morphology characteristics of the dissimilar material weld obtained in conventional laser welding are extracted. The upper molten width of the dissimilar material weld on the left and right sides of the welding center line is a and 1 and a 2 (Assume a 1 2 ), the lower weld width is b 1 and b 2 (Assume b 1 2 ), the weld areas are s 1 and 2 (Assume s 1 2 ), the geometric asymmetry degree R of the weld is determined by the asymmetry degree R of the upper end of the weld a =(a 2 -a 1 ) / a 1 , the asymmetry degree R of the lower end of the weld b =(b 2 -b 1 ) / b 1 and the asymmetry degree R of the weld area s =(s 2 -s 1 ) / s 1 Find, that is, R = η a R a +η b R b +η s R s , where η a , η b and η s are the asymmetry degree R of the upper end of the weld a , the asymmetry degree R of the lower end of the weld b and the asymmetry degree of the weld area R s The weight coefficient of , and satisfies η a +η b +η s =1, energy distribution coefficient R on the left side of welding center line 1 =(1+R) / (2+R), energy distribution coefficient R on the right side of the welding center line 2 =1-R 1 ​​​;

[0008] 2) According to the energy distribution coefficient of dissimilar materials, the energy distribution control scheme and adjustment parameters are determined. Laser power and scanning path length are important parameters affecting energy distribution during scanning laser welding. The energy distribution control scheme mainly includes constant power asymmetric "∞" scanning laser control scheme and variable power asymmetric "∞" scanning laser control scheme. The constant power asymmetric "∞" scanning laser control scheme is suitable for the working condition with weaker degree of weld geometric asymmetry, that is, when R≤1 and R 1 ≤2R 2 The variable power asymmetric “∞” scanning laser control scheme is suitable for the working conditions with serious asymmetry of weld geometry, that is, when R>1 and R 1 >2R 2 When the same energy distribution control scheme is used, the welding process parameters such as welding speed, scanning frequency and defocusing amount remain unchanged during the control process;

[0009] 3) Adjust the gap of the dissimilar material welding plates to complete the positioning and clamping of the welding plates. According to the gap requirements of the dissimilar material welding plates, select the gap adjustment block of the corresponding width, adjust the end face of the welding plate to align with the end face of the gap adjustment block, and cooperate with the movement, positioning and clamping mechanism of the welding plate to complete the gap adjustment and positioning and clamping of the dissimilar material welding plates;

[0010] 4) Adjust other welding process parameters to complete the welding process of dissimilar materials. The asymmetric "∞" shape scanning laser controls the welding process of dissimilar materials using argon gas with a concentration of 99.99% as the shielding gas. The energy distribution adjustment parameters during the welding process are the laser power and the length of the laser scanning path. Other main welding process parameters during the welding process also include welding speed, scanning frequency, defocusing amount and shielding gas flow rate. The specific operations are as follows: determine the energy distribution control scheme and adjustment parameters during the welding process of dissimilar materials, adjust the gap and position the plates for dissimilar material welding, turn on the shielding gas and laser, comprehensively adjust other main welding process parameters, and complete the asymmetric "∞" shape scanning laser welding of dissimilar materials.

[0011] Furthermore, in the process of constant power asymmetric “∞” shaped scanning laser regulation of dissimilar material welding, the laser power remains unchanged. The energy distribution during welding is mainly affected by the action time of the laser beam. When the welding speed and the scanning frequency remain unchanged, the laser action time is linearly related to the length of the laser scanning path. Therefore, on both sides of the dissimilar material welding center line, an asymmetric “∞” shaped laser scanning path with different path lengths is used to adjust the energy distribution. The scanning path lengths on the left and right sides of the welding center line are L 1 and L 2 , L 1 / L 2 =α(R 1 / R 2 ), α is the scan path adjustment correction coefficient.

[0012] Furthermore, in the process of dissimilar material welding regulated by variable power asymmetric “∞” scanning laser, the energy distribution is mainly affected by the laser power and the length of the laser scanning path. Therefore, on both sides of the dissimilar material welding center line, the laser beam with an asymmetric “∞” scanning path with periodic power change is used to adjust the energy distribution. The laser powers on the left and right sides of the welding center line are P and P, respectively. 1 and P 2 , the scanning path lengths on the left and right sides of the welding center line are L 3 and L 4 , P 1 L 3 / P 2 L 4 =β(R 1 / R 2 ), β is the correction factor for coordinated adjustment of laser power and scanning path length.

[0013] Furthermore, in the variable power asymmetric “∞” scanning laser control scheme, the laser beam scanning period is T, and the laser power P on both sides of the welding center line within a scanning period T is 1 and P 2 The action time is T 1 and T 2 , T 1 =TL 3 / (L 3 +L 4 ), T 2 =TT 1 .

[0014] Compared with the prior art, the above technical solution conceived by the present invention has the following beneficial effects:

[0015] 1. The present invention proposes a control method for asymmetric "∞"-shaped scanning laser welding of dissimilar materials, which uses a variable power laser beam and an asymmetric "∞"-shaped scanning path to adjust the energy distribution in the dissimilar material welding process, inhibit the formation of welding defects, and complete the positioning and clamping of the dissimilar material welding plate through the cooperation of the gap adjustment block and the positioning and clamping mechanism, so as to complete the dissimilar material welding process with high efficiency and high quality;

[0016] 2. The present invention proposes a control method for asymmetric "∞"-shaped scanning laser welding of dissimilar materials, which adopts two control schemes: constant power asymmetric "∞"-shaped scanning laser and variable power asymmetric "∞"-shaped scanning laser, to meet the personalized improvement needs of different degrees of geometric asymmetry of dissimilar material welds;

[0017] 3. The present invention proposes a control method for asymmetric "∞"-shaped scanning laser welding of dissimilar materials. Through the coordination of components such as a gap adjustment block, a positioning clamping mechanism and a welding platform, the gap adjustment and positioning clamping time of dissimilar material welding plates are reduced while ensuring the gap adjustment accuracy of the welding plates, thereby improving the welding efficiency of dissimilar materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A schematic diagram of a control process of an asymmetric "∞"-shaped scanning laser welding of dissimilar materials according to the present invention;

[0019] Figure 2 This is a schematic diagram of the cross-section of the weld of dissimilar materials a of the present invention;

[0020] Figure 3 It is a schematic diagram of the constant power asymmetric “∞”-shaped scanning laser control process of the present invention;

[0021] Figure 4 It is a schematic diagram of the gap adjustment and positioning clamping process of the dissimilar material welding plates of the present invention;

[0022] Figure 5 This is a schematic diagram of the cross-section of the weld of dissimilar materials b of the present invention;

[0023] Figure 6 It is a schematic diagram of the variable power asymmetric "∞"-shaped scanning laser control process of the present invention;

[0024] [Description of Reference Numerals]

[0025] 1-welding platform, 2-low carbon steel a plate, 3-stainless steel plate, 4-longitudinal moving mechanism, 5-U-shaped block, 6-gap adjustment block, 7-longitudinal positioning mechanism, 8-clamping mechanism, 9-lateral moving mechanism, 10-laser beam, 11-shielding gas nozzle, 12-"∞" shaped scanning path, 13-welding pool, 14-dissimilar material a weld, 15-low carbon steel b plate, 16-aluminum alloy plate, 17-dissimilar material b weld, 1401-low carbon steel a side weld, 1402-stainless steel side weld, 1701-low carbon steel b side weld, 1702-aluminum alloy side weld. DETAILED DESCRIPTION

[0026] In order to make the technical problems, technical solutions and advantages to be solved by the present invention clearer, the following will be described in detail with reference to the accompanying drawings and specific embodiments. The exemplary embodiments of the present invention are only used to explain the present invention and are not intended to limit the present invention. The present invention is further described in detail using two specific embodiments in conjunction with the accompanying drawings:

[0027] A control method for asymmetric "∞"-shaped scanning laser welding of dissimilar materials, according to the requirements for improving the quality of dissimilar material weld formation and welding efficiency, adopts a variable power laser beam 10 and an asymmetric "∞"-shaped scanning path 12 to adjust the energy distribution of a welding molten pool 13 during the dissimilar material welding process, and inhibits the formation of welding defects such as geometric asymmetry and pores of dissimilar material welds; through the use of a gap adjustment block 6 and a positioning clamping mechanism, the gap adjustment and positioning clamping time of dissimilar material welding plates are reduced, and the dissimilar material welding process is completed with high efficiency and high quality, such as Figure 1 shown.

[0028] Example 1

[0029] In this embodiment, the dissimilar material welding plates are selected as 2 mm thick low carbon steel a plate 2 and stainless steel plate 3, respectively, and the cross-sectional morphological characteristics of the dissimilar material a weld 14 of conventional laser single-pass welding under the welding process parameters of 0.02 mm gap between the dissimilar material welding plates, 3000 W laser power, 4 m / min welding speed, and 0 mm defocus are extracted, as shown in FIG. Figure 2 As shown. The upper melting width a of the low carbon steel side a weld 1401 1 0.47mm, lower melting width b 1 0.27mm, area s 1 0.45mm 2 , upper weld width a of stainless steel side weld 1402 2 0.72mm, lower melting width b 2 0.47mm, area s 2 0.67mm 2 , the asymmetry degree R of the upper end of the weld a is 0.53, and the asymmetry degree R b is 0.74, and the asymmetry degree of the weld area R s The influence coefficient of weld width on the weld is set to 0.49 by analyzing the relationship between the cross-sectional morphology of the weld 14 of the dissimilar material and the comprehensive performance of the joint. a is 0.32, and the influence coefficient of weld width is η b is 0.28, and the weld area influence coefficient η s is 0.4, the geometric asymmetry degree R of the weld 14 of the dissimilar material a is 0.57, and the energy distribution coefficient R of the low carbon steel a side is 1 The energy distribution coefficient R on the stainless steel side is 0.61. 2 It is 0.39.

[0030] Since the geometric asymmetry degree R of the weld 14 of the dissimilar material a is 0.57, R<1, a constant power asymmetric “∞” shaped scanning laser is used to control the welding process, such as Figure 3By considering the comprehensive conditions such as the thermophysical parameters of low carbon steel and stainless steel, laser beam parameters and ambient temperature, the scanning path length adjustment correction coefficient α is determined to be 1.05, and the equation of the "∞" scanning curve is X = 0.5Asin(θ), Y = 0.5Asin(2θ), and the distance from the a side of the low carbon steel Stainless steel side distance L 1 / L 2 =A 1 / A 2 =1.64, the "∞" scanning amplitude A of the low carbon steel a side in this embodiment 1 The "∞" scanning amplitude A on the stainless steel side is 1mm. 2 It is 0.61mm.

[0031] like Figure 4 As shown, a U-shaped block 5 is fixedly provided in the middle of the upper surface of the welding platform 1, a longitudinal positioning mechanism 7 is slidably provided in the upper slide groove of the U-shaped block 5, a gap adjustment block 6 that can be flexibly plugged in and out is provided in the upper left part of the U-shaped block 5 and the upper groove of the longitudinal positioning mechanism 7, the width c of the gap adjustment block 6 is the same as the gap required for welding plates of dissimilar materials, four groups of longitudinal moving mechanisms 4 are provided on the upper part of the welding platform 1, a transverse moving mechanism 9 is provided at the end of the longitudinal moving mechanism 4, and a clamping mechanism 8 is provided at the end of the transverse moving mechanism 9. The specific operations of gap adjustment and positioning clamping of dissimilar material welding plates in this embodiment are as follows: place the low carbon steel a plate 2 and the stainless steel plate 3 horizontally on the surface of the U-shaped block 5, and keep the left end face of the welding plate aligned with the left end positioning face of the U-shaped block 5, move the longitudinal moving mechanism 4 and the transverse moving mechanism 9 so that the clamping mechanism 8 can smoothly complete the clamping of the welding plate, according to the 0.02mm gap adjustment requirement of the low carbon steel a plate 2 and the stainless steel plate 3, select two gap adjustment blocks 6 with a width of 0.02mm and place them respectively on the upper left side of the U-shaped block 5 and in the upper groove of the longitudinal positioning mechanism 7, slide the longitudinal positioning mechanism 7 to align its left end face with the right end face of the welding plate, adjust the transverse position of the welding plate by the transverse moving mechanism 9, so that the front end face of the low carbon steel a plate 2 and the rear end face of the stainless steel plate 3 are respectively aligned with the front and rear end faces of the gap adjustment block 6, fix the longitudinal positioning mechanism 7 and the transverse moving mechanism 9, take out the gap adjustment block 6, and complete the gap adjustment and positioning clamping of the dissimilar material welding plates.

[0032] The constant power laser beam 10 and the shielding gas nozzle 11 move synchronously along the asymmetric "∞"-shaped scanning path 12, and the low carbon steel a plate 2 and the stainless steel plate 3 are melted under the radiation of the laser beam 10. The shielding gas nozzle 11 continuously blows argon gas with a concentration of 99.99% to the welding area to prevent the molten metal from being oxidized until the welding of dissimilar materials is completed. In this embodiment, other welding process parameters are selected as laser power 3200W, welding speed 4m / min, defocusing amount 0mm, scanning frequency 50Hz, and shielding gas flow rate 20L / min.

[0033] Example 2

[0034] In this embodiment, the dissimilar materials are selected as 3 mm thick low carbon steel b plate 15 and aluminum alloy plate 16, respectively, and the cross-sectional morphological characteristics of the dissimilar material b weld 17 of conventional laser single-pass welding under the welding process parameters of 0.02 mm gap between the dissimilar material welding plates, 2200 W laser power, 1.5 m / min welding speed, and +1 mm defocus are extracted, as shown in FIG. Figure 5 As shown. Upper melting width a of low carbon steel b side weld 1701 3 0.51mm, lower melting width b 3 0.32mm, area s 3 0.99mm 2 , the upper melting width a of the aluminum alloy side weld 1702 4 1.29mm, lower melting width b 4 0.77mm, area s 4 2.47mm 2 , the asymmetry degree R of the upper end of the weld a is 1.53, and the asymmetry degree R b is 1.41, and the asymmetry degree of the weld area R s is 1.49. By analyzing the relationship between the cross-sectional morphology of the weld 17 of dissimilar materials and the comprehensive performance of the joint, the influence coefficient of the weld width η is set. a is 0.33, the influence coefficient of weld width η b is 0.24, and the weld area influence coefficient η S is 0.43, the geometric asymmetry degree R of the dissimilar material b weld 17 is 1.48, and the energy distribution coefficient R of the low carbon steel b side is 1 The energy distribution coefficient R on the aluminum alloy side is 0.71. 2 It is 0.29.

[0035] Since the geometric asymmetry degree R of the weld 17 of the dissimilar material b is 1.48, R>1, the welding process is regulated by using a variable power asymmetric “∞” scanning laser, such as Figure 6Considering the comprehensive conditions such as the thermophysical parameters of low carbon steel and aluminum alloy, laser beam parameters and ambient temperature, the correction coefficient β of the coordinated adjustment of laser power and scanning path length is determined to be 1.02, and the scanning path lengths on the left and right sides of the welding center line are respectively the distance L on the b side of the low carbon steel 3 Distance from aluminum alloy side L 4 , the laser power on the left and right sides of the welding center line is the power P on the b side of the low carbon steel 1 And aluminum alloy side power P 2 , P 1 L 3 =2.50P 2 L 4 In this implementation, the "∞" scanning amplitude A of the low carbon steel b side 3 The scanning amplitude A of the aluminum alloy side "∞" shape is 1.2mm 4 0.72mm, low carbon steel b side laser power P 1 The laser power on the aluminum alloy side is 3000W. 2 is 2000W, laser power P 1 Action time in a single cycle T 1 is 6.25ms, laser power P 2 Action time in a single cycle T 2 It is 3.75ms.

[0036] A gap adjustment block 6 with a width of 0.02 mm is selected to adjust the gap between the low carbon steel b plate 15 and the aluminum alloy plate 16. The specific steps of gap adjustment and positioning clamping for welding dissimilar materials are the same as those in Example 1 and will not be repeated here.

[0037] The variable power laser beam 10 and the shielding gas nozzle 11 move synchronously along the asymmetric "∞"-shaped scanning path 12. The low carbon steel b plate 15 and the aluminum alloy plate 16 melt under the radiation of the laser beam 10 to form a good dissimilar material b weld 17. In this embodiment, other welding process parameters are selected as a welding speed of 1.5 m / min, a defocus of +1 mm, a scanning frequency of 100 Hz, and a shielding gas flow rate of 15 L / min.

[0038] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A control method for asymmetric "∞" scanning laser welding of dissimilar materials, which uses a variable power laser beam and an asymmetric "∞" scanning path to adjust the energy distribution in the process of laser welding of dissimilar materials, and controls the welding process and weld quality of dissimilar materials. It is characterized in that The method comprises the following steps: 1) According to the degree of geometric asymmetry of the dissimilar material weld, the energy distribution coefficient is determined, and the cross-sectional geometric morphology characteristics of the dissimilar material weld obtained in conventional laser welding are extracted. The upper molten width of the dissimilar material weld on the left and right sides of the welding center line is a and 1 and a 2 , where a 1 2 , the lower weld width is b 1 and b 2 , where b 1 2 , the weld areas are s 1 and 2 , where s 1 2 The geometric asymmetry degree R of the weld is determined by the asymmetry degree R of the upper end of the weld. a =(a 2 -a 1 ) / a 1 , the asymmetry degree R of the lower end of the weld b =(b 2 -b 1 ) / b 1 and the asymmetry degree R of the weld area s =(s 2 -s 1 ) / s 1 Find, that is, R = η a R a +η b R s +η s R s , where η a , η b and η s are the asymmetry degree R of the upper end of the weld a , the asymmetry degree R of the lower end of the weld b and the asymmetry degree of the weld area R s The weight coefficient of , and satisfies η a +η b +η s =1, energy distribution coefficient R on the left side of welding center line 1 =(1+R) / (2+R), energy distribution coefficient R on the right side of the welding center line 2 =1-R 1 ;​​​ 2) According to the energy distribution coefficient of dissimilar materials, the energy distribution control scheme and adjustment parameters are determined. Laser power and scanning path length are important parameters affecting energy distribution during scanning laser welding. The energy distribution control scheme includes constant power asymmetric "∞" scanning laser control scheme and variable power asymmetric "∞" scanning laser control scheme. The constant power asymmetric "∞" scanning laser control scheme is suitable for the working condition with weaker degree of weld geometric asymmetry, that is, when R≤1 and R 1 ≤2R 2 The variable power asymmetric "∞" scanning laser control scheme is suitable for the working conditions with serious geometric asymmetry of the weld, that is, when R>1 and R 1 >2R 2 When the same energy distribution control scheme is used, the welding process parameters of welding speed, scanning frequency and defocus amount remain unchanged during the control process; 3) Adjust the gap of the dissimilar material welding plates to complete the positioning and clamping of the welding plates. According to the gap requirements of the dissimilar material welding plates, select the gap adjustment block of the corresponding width, adjust the end face of the welding plate to align with the end face of the gap adjustment block, and cooperate with the positioning and clamping mechanism of the welding plate to complete the gap adjustment and positioning and clamping of the dissimilar material welding plates; 4) Adjusting other welding process parameters to complete the welding process of dissimilar materials. Argon gas with a concentration of 99.99% is used as the shielding gas during the asymmetric "∞" shape scanning laser controlled welding of dissimilar materials. The energy distribution adjustment parameters during the welding process are the laser power and the laser scanning path length. Other main welding process parameters during the welding process also include the welding speed, scanning frequency, defocusing amount and shielding gas flow rate. The specific operations are as follows: determining the energy distribution control scheme and adjustment parameters during the welding of dissimilar materials, adjusting the gap and positioning and clamping the dissimilar material welding plates, turning on the shielding gas and the laser, and comprehensively adjusting other main welding process parameters to complete the asymmetric "∞" shape scanning laser welding of dissimilar materials.

2. According to the control method of asymmetric "∞" scanning laser welding of dissimilar materials as described in claim 1, It is characterized in that Constant power asymmetric "∞" scanning laser regulation During the welding process of dissimilar materials, the laser power remains unchanged. The energy distribution during welding is mainly affected by the action time of the laser beam. When the welding speed and scanning frequency remain unchanged, the laser action time is linearly related to the length of the laser scanning path. Therefore, on both sides of the welding center line of the dissimilar materials, an asymmetric "∞" laser scanning path with different path lengths is used to adjust the energy distribution. The scanning path lengths on the left and right sides of the welding center line are L 1 and L 2 , L 1 / L 2 =α(R 1 / R 2 ), α is the scan path adjustment correction coefficient.

3. According to the control method of asymmetric "∞" scanning laser welding of dissimilar materials as described in claim 1, It is characterized in that In the process of dissimilar material welding, the energy distribution is mainly affected by the laser power and the length of the laser scanning path. Therefore, on both sides of the dissimilar material welding center line, the laser beam with an asymmetric "∞" scanning path with periodic power changes is used to adjust the energy distribution. The laser powers on the left and right sides of the welding center line are P 1 and P 2 , the scanning path lengths on the left and right sides of the welding center line are L 3 and L 4 , P 1 L 3 / P 2 L 4 =β(R 1 / R 2 ), β is the correction factor for coordinated adjustment of laser power and scanning path length.

4. According to the control method of asymmetric "∞" scanning laser welding of dissimilar materials as described in claim 3, It is characterized in that In the variable power asymmetric "∞" scanning laser control scheme, the laser beam scanning cycle is T, and the laser power P on both sides of the welding center line within a scanning cycle T 1 and P 2 The action time is T 1 and T 2 , T 1 =TL 3 / (L 3 +L 4 ), T 2 =TT 1 .

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