Titanium alloy skin-framework joint laser swing welding method and system

Abstract

The invention belongs to the technical field of laser welding, discloses a titanium alloy skin-skeleton joint laser swing welding method and system, and relates to an establishment method for forming a process window with good weld forming by introducing characteristic parameters such as energy distribution characteristics and speed change. The problems that in an existing titanium alloy skin-framework joint welding method, the defects such as splashing and undercut occur frequently, and the mechanical property is weak are effectively solved, the mechanical property and quality stability of a welded joint are improved, and therefore the high-quality and efficient welding requirement is met, and technical support is provided for wide application of a titanium alloy skin-framework structure in the aerospace field. No external means or multiple working procedures are needed, and optimal control over welding seam forming is achieved only by flexibly adjusting parameters such as the swing track, the frequency and the amplitude. On the premise of ensuring the stable welding quality, the welding defects such as air holes, undercut and splashing are effectively reduced, and the welding performance of the titanium alloy skin framework joint is remarkably improved.

Description

Technical Field

[0001] The invention belongs to the technical field of laser welding, and in particular relates to a laser swing welding method and system for a titanium alloy skin-frame joint. Background Art

[0002] With the rapid development of aerospace technology, the demand for lightweight and high performance of aircraft structures continues to increase. Titanium alloys have become key structural materials in the aerospace field due to their low density, high specific strength, corrosion resistance and good thermal stability. They are widely used in key parts such as aircraft skins, frames, and bulkheads. Among them, the skin-frame joint is a typical complex structure, which requires the welding process to meet the needs of precision connection while ensuring the strength and service performance of the joint.

[0003] However, titanium alloy materials show significant high activity and high thermal conductivity during welding, which puts forward strict requirements on the welding environment; at the same time, its easy oxidation characteristics easily lead to the degradation of weld quality at high temperature. In addition, the skin-frame joint has complex geometry and uneven welding gap. Traditional laser welding is difficult to effectively adapt to these structural characteristics, and defects such as pores, lack of fusion and poor weld formation are prone to occur.

[0004] Laser oscillation welding uses the movement of the laser's built-in galvanometer to make the laser heat source oscillate along a specific trajectory. The oscillation of the heat source effectively increases the welding path length and reduces the negative impact of heat input on the joint quality; the stirring effect of the heat source promotes the escape of gas in the melt and reduces the porosity; the laser oscillation effectively increases the joint lap area and significantly increases the mechanical properties of the joint. However, the existing technology still has the following problems in parameter optimization and process window establishment:

[0005] (1) The quantitative analysis method for the energy distribution characteristics of the weld is still imperfect, making it difficult to accurately evaluate the energy input characteristics of laser oscillating welding.

[0006] (2) There is a lack of systematic research on the influence of laser oscillation parameters on weld formation. The determination of the process window mainly relies on experimental experience, which is inefficient.

[0007] (3) There are many process parameters in swing welding, and there is a lack of clear understanding and systematic control methods for the synergistic effects between the parameters. Improper parameter adjustment can easily lead to deterioration of the forming process.

[0008] Therefore, it is urgent to propose a more standardized laser oscillating welding method with adjustable parameters to meet the high-quality and high-efficiency requirements of titanium alloy skin-skeleton joint welding. Summary of the invention

[0009] In view of the problems existing in the prior art, the present invention provides a titanium alloy skin-frame joint laser swing welding method and system.

[0010] The present invention is achieved in that a titanium alloy skin-frame joint laser oscillation welding method comprises:

[0011] S101, obtaining the relationship between the swing welding process parameters and the laser energy distribution characteristics and trajectory motion characteristics based on the swing laser beam parameters;

[0012] S102, establishing optimization constraints for energy distribution characteristics and motion characteristics of the laser oscillating welding beam; obtaining a preset range of process parameters;

[0013] S103, substituting the process parameter values ​​within the preset range into the optimization constraints of the energy distribution characteristics and motion characteristics of the laser oscillating welding beam, and then combining the process parameters that simultaneously satisfy the optimization constraints of the energy distribution characteristics and motion characteristics of the laser oscillating welding beam into the optimized process parameters.

[0014] Further, the laser beam parameter is the laser diameter d0; the process parameters include laser power P, welding speed v, swing trajectory, swing amplitude A, and swing frequency f;

[0015] The laser trajectory motion characteristics include the geometric shape, path length and speed change characteristics of the welding beam trajectory during the swing process; by analyzing the influence of different swing trajectories on the weld morphology and internal structure, the influence of the swing trajectory on the energy distribution is determined;

[0016] Taking the circular swing trajectory as an example, the motion equation of the circular swing trajectory is:

[0017]

[0018] Where x and y are the coordinate trajectories of the beam motion, v is the welding speed, A is the swing amplitude, and f is the swing frequency. By taking the derivative of the motion equation with respect to time, we can get the change of the beam swing velocity component and the overall velocity with time, as shown in the following formula:

[0019]

[0020] Among them, V x 、V y They are the components of the beam along the x and y directions at the moment. Finally, by inputting the set parameters and analyzing the average speed and maximum speed of each trajectory, the velocity distribution characteristics of the swing trajectory can be obtained.

[0021] V 平均 =mean(V 合 )

[0022] V max =max(V 合 ).

[0023] Furthermore, the optimization constraint conditions of the motion feature are:

[0024] V max <980mm / s;

[0025] The reason for limiting the minimum average speed is to ensure sufficient stirring effect, so that the molten pool liquid can be fully spread to form a uniform, straight weld with consistent molten width; the reason for limiting the maximum speed is to prevent the molten pool liquid from being accelerated to a critical speed and flying out of the molten pool from the rear end to form splash defects. At the same time, the increase in speed will also aggravate the unevenness of the swing welding liquid level, thereby forming an undercut defect, which becomes a weak point in mechanical properties.

[0026] Furthermore, the laser energy distribution characteristics refer to the energy accumulation and distribution of the laser beam on the two-dimensional plane of the welding workpiece during the entire welding process; the main characteristic parameters include laser comprehensive linear energy density, laser transient linear energy density, and laser energy peak value;

[0027] Assume that the laser beam is a planar heat source and the beam intensity conforms to an ideal Gaussian distribution.

[0028]

[0029] Integrating the light intensity formula over the entire time domain can yield the energy distribution in the entire two-dimensional plane during laser oscillation welding.

[0030]

[0031] The total energy input is

[0032]

[0033] Where m and n are the lengths of the weld in the x direction, q and p are the widths of the weld in the y direction; the laser comprehensive linear energy density E 0 Characterizes the uniformity of the overall heat input. Its physical meaning is the average energy absorbed per unit length of the track. The calculation formula is:

[0034]

[0035] Where L is the actual movement length of the light beam, and the calculation formula is:

[0036]

[0037] Laser transient linear energy density E i Characterize the local heat input, which is the actual energy absorbed by the unit length trajectory after combining the speed of the corresponding point of the beam swing trajectory, the beam action time and other factors. The calculation formula is:

[0038]

[0039] The energy peak reflects the value at which the energy accumulation on the two-dimensional plane of the workpiece is maximum after the welding process is completed.

[0040] I max =Max(E(x,y))

[0041] Furthermore, the optimization constraint of the energy distribution is:

[0042]

[0043] The limiting principle for the comprehensive laser line energy density is to allow the heat to act on the workpiece plane to the greatest extent and most evenly, avoiding local overheating and other phenomena; the limiting principle for the instantaneous laser line energy density is to allow the laser input to maintain the heat level for the stable existence of the small holes in the molten pool, avoiding local instability due to insufficient heat, the periodic collapse of small holes, and the generation of defects such as pores, spatter, and depressions.

[0044] Further, the method for optimizing the process parameters for good forming in the titanium alloy oscillating laser welding is as follows:

[0045] Obtaining a preset range of the process parameters according to the working range of each parameter of the welding system or the process requirements;

[0046] The obtained process parameter interval is input into the optimization constraint conditions. When the process parameters satisfy both the energy distribution characteristic and the motion characteristic optimization constraint conditions, they are retained. Otherwise, they are discarded and the next set of process parameters are verified.

[0047] Another object of the present invention is to provide a titanium alloy skin-frame joint laser oscillation welding system comprising:

[0048] A feature acquisition module, used to acquire the relationship between the swing welding process parameters and the laser energy distribution characteristics and trajectory motion characteristics based on the swing laser beam parameters;

[0049] The constraint condition establishment module is used to establish the optimization constraint conditions of the energy distribution characteristics and motion characteristics of the laser oscillating welding beam; and obtain the preset range of the process parameters;

[0050] The optimization module is used to substitute the process parameter values ​​within a preset range into the optimization constraints of the energy distribution characteristics and motion characteristics of the laser oscillating welding beam, and then the process parameter combination that simultaneously satisfies the optimization constraints of the energy distribution characteristics and motion characteristics of the laser oscillating welding beam is the optimized process parameter.

[0051] Another object of the present invention is to provide a computer device, which includes a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the steps of the titanium alloy skin-skeleton joint laser oscillation welding method.

[0052] Another object of the present invention is to provide a computer-readable storage medium storing a computer program, which, when executed by a processor, enables the processor to perform the steps of the titanium alloy skin-skeleton joint laser oscillation welding method.

[0053] Another object of the present invention is to provide an information data processing terminal, which is used to implement the titanium alloy skin-skeleton joint laser oscillation welding system.

[0054] In view of the technical problems existing in the above-mentioned prior art and the difficulty of solving the problems, the technical solutions to be protected by the present invention and the results and data during the research and development process are closely combined to analyze in detail and deeply how the technical solutions of the present invention solve the technical problems, and some creative technical effects brought about after solving the problems. The specific description is as follows:

[0055] The present invention provides a method and system for controlling the laser oscillating welding process of a titanium alloy skin-skeleton joint. By introducing characteristic parameters such as energy distribution characteristics and speed changes, a method for establishing a good process window for weld formation is formed. The problems of frequent defects such as spatter and undercut, and weak mechanical properties in the existing titanium alloy skin-skeleton joint welding methods are effectively solved, and the mechanical properties and quality stability of the welded joint are improved, thereby meeting the needs of high-quality and efficient welding, and providing technical support for the widespread application of titanium alloy skin-skeleton structures in the aerospace field.

[0056] The present invention proposes a titanium alloy skin skeleton joint welding process based on laser oscillating welding. It does not require external means or multiple processes. It only achieves optimal control of weld formation by flexibly adjusting parameters such as oscillation trajectory, frequency and amplitude. Under the premise of ensuring stable weld quality, it effectively reduces welding defects such as pores, undercuts and spatter, and significantly improves the welding performance of titanium alloy skin skeleton joints.

[0057] Based on the precise quantitative analysis of the energy and speed characteristics of the weld, a scientific and standardized parameter optimization method was proposed, which significantly reduced the reliance on experimental trial and error in welding process development and improved the design efficiency of the welding process. At the same time, it ensured the adjustability of process parameters within a wide range, which is suitable for multi-scenario welding requirements of complex joints.

[0058] The establishment process of this method is not only applicable to laser oscillating welding of titanium alloys, but also has reference value for other materials. From the perspective of motion characteristics and energy distribution, it provides effective ideas and methods for establishing a good process window for oscillating welding surface forming, and provides a reference for high-quality and efficient oscillating welding. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Figure 1 It is a flow chart of the laser oscillating welding method of the titanium alloy skin-frame joint provided in an embodiment of the present invention.

[0060] Figure 2 As shown, the method for optimizing the process parameters for good forming in the titanium alloy oscillating laser welding provided by the embodiment of the present invention is as follows:

[0061] Figure 3 It is a structural block diagram of a titanium alloy skin-frame joint laser oscillation welding system provided in an embodiment of the present invention.

[0062] Figure 4 This is a three-dimensional schematic diagram of energy density provided by an embodiment of the present invention.

[0063] Figure 5 Schematic diagram of energy density cross section provided by an embodiment of the present invention

[0064] Figure 6 Schematic diagram of the top view of the energy density provided by the embodiment of the present invention

[0065] Fig. 7A The schematic diagram of welding under the combination of process parameters a in a common design is shown schematically;

[0066] Figure 7B The welding schematic diagram under the optimized process parameter b combination of the present invention is schematically shown. DETAILED DESCRIPTION

[0067] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0068] like Figure 1 As shown, a titanium alloy skin-frame joint laser oscillation welding method provided by an embodiment of the present invention comprises the following steps:

[0069] S101, obtaining the relationship between the swing welding process parameters and the laser energy distribution characteristics and trajectory motion characteristics based on the swing laser beam parameters;

[0070] S102, establishing optimization constraints for energy distribution characteristics and motion characteristics of the laser oscillating welding beam; obtaining a preset range of process parameters;

[0071] S103, substituting the process parameter values ​​within the preset range into the optimization constraints of the energy distribution characteristics and motion characteristics of the laser oscillating welding beam, and then combining the process parameters that simultaneously satisfy the optimization constraints of the energy distribution characteristics and motion characteristics of the laser oscillating welding beam into the optimized process parameters.

[0072] The laser beam parameter provided in the embodiment of the present invention is the laser diameter d0; the process parameters include the laser power P, the welding speed v, the swing trajectory, the swing amplitude A, and the swing frequency f;

[0073] The laser trajectory motion characteristics include the geometric shape, path length and speed change characteristics of the welding beam trajectory during the swing process; by analyzing the influence of different swing trajectories on the weld morphology and internal structure, the influence of the swing trajectory on the energy distribution is determined;

[0074] Taking the circular swing trajectory as an example, the motion equation of the circular swing trajectory is

[0075]

[0076] By differentiating the equation of motion with respect to time, we can obtain the variation of the beam swing velocity component and the overall velocity with time, as shown in the following formula:

[0077]

[0078] Finally, input the set parameters and analyze the average speed and maximum speed of each trajectory, then the speed distribution characteristics of the swing trajectory can be obtained.

[0079] V 平均 =mean(V 合 )

[0080] V max =max(V 合 ).

[0081] The optimization constraint conditions of the motion features provided by the embodiment of the present invention are:

[0082] V max <980mm / s;

[0083] The reason for limiting the minimum average speed is to ensure sufficient stirring effect, so that the molten pool liquid can be fully spread to form a uniform, straight weld with consistent molten width; the reason for limiting the maximum speed is to prevent the molten pool liquid from being accelerated to a critical speed and flying out of the molten pool from the rear end to form splash defects. At the same time, the increase in speed will also aggravate the unevenness of the swing welding liquid level, thereby forming an undercut defect, which becomes a weak point in mechanical properties.

[0084] The laser energy distribution characteristics provided in the embodiment of the present invention refer to the energy accumulation and distribution of the laser beam on the two-dimensional plane of the welding workpiece during the entire welding process; the main characteristic parameters include laser comprehensive linear energy density, laser transient linear energy density, and laser energy peak value;

[0085] Assume that the laser beam is a planar heat source and the beam intensity conforms to an ideal Gaussian distribution.

[0086]

[0087] Integrating the light intensity formula over the entire time domain can yield the energy distribution in the entire two-dimensional plane during laser oscillation welding.

[0088]

[0089] The total energy input is

[0090]

[0091] Where m and n are the lengths of the weld in the x direction, q and p are the widths of the weld in the y direction; the laser comprehensive linear energy density E 0 Characterizes the uniformity of the overall heat input. Its physical meaning is the average energy absorbed per unit length of the track. The calculation formula is:

[0092]

[0093] Where L is the actual movement length of the light beam, and the calculation formula is:

[0094]

[0095] Laser transient linear energy density E i Characterize the local heat input, which is the actual energy absorbed by the unit length trajectory after combining the speed of the corresponding point of the beam swing trajectory, the beam action time and other factors. The calculation formula is:

[0096]

[0097] The energy peak reflects the value at which the energy accumulation on the two-dimensional plane of the workpiece is maximum after the welding process is completed.

[0098] I max =Max(E(x,y))

[0099] The optimization constraint condition of energy distribution provided by the embodiment of the present invention is:

[0100]

[0101] The limiting principle for the comprehensive laser line energy density is to allow the heat to act on the workpiece plane to the greatest extent and most evenly, avoiding local overheating and other phenomena; the limiting principle for the instantaneous laser line energy density is to allow the laser input to maintain the heat level for the stable existence of the small holes in the molten pool, avoiding local instability due to insufficient heat, the periodic collapse of small holes, and the generation of defects such as pores, spatter, and depressions.

[0102] like Figure 2 As shown, the method for optimizing the process parameters for good forming in the titanium alloy oscillating laser welding provided by the embodiment of the present invention is as follows:

[0103] S201, obtaining a preset range of the process parameters according to the working range of each parameter of the welding system or the process requirements;

[0104] S202, input the obtained process parameter interval into the optimization constraint condition, and retain the process parameter when it satisfies both the energy distribution characteristic and the motion characteristic optimization constraint condition, otherwise, discard it and verify the next set of process parameters.

[0105] like Figure 3 As shown, a titanium alloy skin-frame joint laser oscillation welding system provided by an embodiment of the present invention comprises:

[0106] A feature acquisition module, used to acquire the relationship between the swing welding process parameters and the laser energy distribution characteristics and trajectory motion characteristics based on the swing laser beam parameters;

[0107] The constraint condition establishment module is used to establish the optimization constraint conditions of the energy distribution characteristics and motion characteristics of the laser oscillating welding beam; and obtain the preset range of the process parameters;

[0108] The optimization module is used to substitute the process parameter values ​​within a preset range into the optimization constraints of the energy distribution characteristics and motion characteristics of the laser oscillating welding beam, and then the process parameter combination that simultaneously satisfies the optimization constraints of the energy distribution characteristics and motion characteristics of the laser oscillating welding beam is the optimized process parameter.

[0109] Another object of the present invention is to provide a computer device, which includes a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the steps of the titanium alloy skin-skeleton joint laser oscillation welding method.

[0110] Another object of the present invention is to provide a computer-readable storage medium storing a computer program, which, when executed by a processor, enables the processor to perform the steps of the titanium alloy skin-skeleton joint laser oscillation welding method.

[0111] Another object of the present invention is to provide an information data processing terminal, which is used to implement the titanium alloy skin-skeleton joint laser oscillation welding system.

[0112] The present invention is specifically implemented:

[0113] Specific embodiments of the present invention are:

[0114] Example 1 - Optimization of the swing laser welding process for marine titanium alloy propeller blades

[0115] Welding parameter adjustment:

[0116] Aiming at the complex curved surface and dynamic load requirements of marine titanium alloy (Ti-6Al-4V) propeller blades, the key parameters of oscillating laser welding are optimized by combining orthogonal tests with numerical simulations, including: laser power (3.0-4.5kW), oscillation frequency (50-200Hz), welding speed (1.2-2.0m / min) and spot diameter (0.2-0.5mm). The parameter setting is based on the blade thickness (5-12mm) and the stringent requirements of the marine environment for corrosion resistance and fatigue resistance, ensuring uniform weld penetration and minimization of the heat affected zone (HAZ).

[0117] Application of swing laser welding technology:

[0118] The oscillating laser welding technology uses dynamic control of the laser beam's oscillating trajectory (such as an "∞" shape or a sinusoidal waveform) to significantly improve keyhole stability and suppress common hydrogen embrittlement and porosity problems in titanium alloy welding. The oscillating mode effectively disperses energy input, avoids grain coarsening caused by local overheating, and enhances the fluidity of the molten pool, improving the consistency of weld formation.

[0119] Weld morphology and performance optimize surface quality: Oscillating laser welding makes the weld surface smooth and flat (roughness ≤ Ra3.2μm), meeting the fluid dynamics requirements of marine propellers at high speeds and reducing the risk of cavitation corrosion.

[0120] Microstructure: By optimizing the oscillation parameters, fine equiaxed crystals are formed in the weld area, and the width of the heat-affected zone is controlled within 0.5mm, which significantly improves the tensile strength (≥900MPa) and fracture toughness of the joint.

[0121] Corrosion resistance: Combined with argon double protection (front and back), the weld has no pitting after 1000 hours of salt spray test in 3.5% NaCl solution, and the corrosion rate is less than 1.2 times that of the base material.

[0122] Quality Control and Process Validation:

[0123] Online monitoring: High-speed cameras and infrared thermal imagers are used to monitor the dynamics of the molten pool and the temperature field distribution in real time, and spectral analysis is combined to detect spatter and composition changes during the welding process.

[0124] Nondestructive testing: The welds were tested by X-ray (in accordance with ISO 17636) and ultrasonic testing, with a porosity of ≤0.5% and no cracks or unfused defects were found.

[0125] Service verification: Under simulated marine alternating loads (frequency 5 Hz, stress amplitude 300 MPa), the fatigue life of the optimized welded joint reaches 1×10^7 cycles, which is 40% higher than traditional laser welding.

[0126] Example 2 - High-precision welding of titanium alloy skin skeleton structure of hypersonic aircraft

[0127] The control surfaces of hypersonic vehicles face complex service environments with time-varying coupling, such as heat loads of ≥1000℃, random vibration loads of ≥5g (0-2kHz), and pressure loads of 2-20kPa. The joints are required to have high service performance such as high temperature resistance and fatigue resistance, which puts forward extremely high requirements on the joint geometry, surface forming, and mechanical properties. The welding parameters need to meet the above conditions to adapt to the characteristics of titanium alloy components.

[0128] The method for optimizing the surface forming process parameters in titanium alloy laser oscillation welding provided by the embodiment of the present invention comprises the following steps:

[0129] Step 1: Obtain the relationship between the swing welding process parameters and the laser energy distribution characteristics and trajectory motion characteristics according to the swing laser beam parameters;

[0130] Step 2: Establish the optimization constraint conditions of the energy distribution characteristics and motion characteristics of the laser oscillating welding beam; obtain the preset range of the process parameters;

[0131] Step 3: Substitute the process parameter values ​​within the preset range into the optimization constraints of the energy distribution characteristics and motion characteristics of the laser oscillating welding beam, and then the process parameter combination that simultaneously satisfies the optimization constraints of the energy distribution characteristics and motion characteristics of the laser oscillating welding beam is the optimized process parameter.

[0132] In the embodiment of the present invention, the laser beam parameters include the laser diameter d0; the process parameters include the laser power P, the welding speed v, the swing trajectory, the swing amplitude A, and the swing frequency f.

[0133] In the embodiment of the present invention, the laser trajectory motion characteristics include the geometric shape, path length and speed change characteristics of the welding beam trajectory during the swinging process. By analyzing the influence of different swinging trajectories on the weld morphology and internal structure, the influence of the swinging trajectory on the energy distribution is determined.

[0134] In the embodiment of the present invention, a circular swing trajectory is used, and the motion equation of the circular swing trajectory is:

[0135]

[0136] By differentiating the equation of motion with respect to time, we can obtain the variation of the beam swing velocity component and the overall velocity with time, as shown in the following formula:

[0137]

[0138] Finally, input the set parameters and analyze the average speed and maximum speed of each trajectory, then the speed distribution characteristics of the swing trajectory can be obtained.

[0139] V 平均 =mean(V 合 )

[0140] V max =max(V 合 )

[0141] In the embodiment of the present invention, the optimization constraint condition of the motion feature is: max <V' max , where V' max is the maximum value of the beam speed under empirical conditions, which can also be calculated from theory. max =980mm / s.

[0142] In the embodiment of the present invention, the laser energy distribution characteristics refer to the energy accumulation and distribution of the laser beam on the two-dimensional plane of the welding workpiece during the entire welding process. The main characteristic parameters include laser comprehensive linear energy density, laser transient linear energy density, and laser energy peak value.

[0143] Assume that the laser beam is a planar heat source and the beam intensity conforms to an ideal Gaussian distribution.

[0144]

[0145] Integrating the light intensity formula over the entire time domain can yield the energy distribution in the entire two-dimensional plane during laser oscillation welding.

[0146]

[0147] The total energy input is

[0148]

[0149] Where m and n are the length of the weld in the x direction, and q and p are the width of the weld in the y direction. Laser comprehensive linear energy density E 0Characterizes the uniformity of the overall heat input. Its physical meaning is the average energy absorbed per unit length of the track. The calculation formula is:

[0150]

[0151] Where L is the actual movement length of the light beam, and the calculation formula is:

[0152]

[0153] Laser transient linear energy density E i Characterize the local heat input, which is the actual energy absorbed by the unit length trajectory after combining the speed of the corresponding point of the beam swing trajectory, the beam action time and other factors. The calculation formula is:

[0154]

[0155] The energy peak reflects the value at which the energy accumulation on the two-dimensional plane of the workpiece is maximum after the welding process is completed.

[0156] I max =Max(E(x,y))

[0157] Furthermore, the optimization constraint of energy distribution is

[0158] 9.534J / mm <E 0 <3.183J / mm

[0159] E i <3.101J / mm

[0160] In an embodiment of the present invention, the preset range of the process parameters is obtained according to the working range of each parameter of the welding system or the process requirements.

[0161] In an embodiment of the present invention, the process parameter value is input into the optimization constraint condition, and when the process parameter value satisfies the optimization constraint conditions of the adjustable annular laser beam diameter and the center point line energy at the same time, it is retained; otherwise, it is discarded and the next set of process parameters is verified.

[0162] The following is a detailed introduction to the method of the present invention using the swing welding of titanium alloy skin skeleton joints as an example. Laser swing welding redistributes the laser input energy to make the joint geometry adjustable and greatly improve the mechanical properties. However, there are many adjustable parameters for swing welding, and the interaction between parameters is unclear. The selection and adjustment of process parameters are blind, and defects such as undercut and spatter are prone to occur. The present invention proposes a method for accurately constraining the motion characteristics and energy distribution of the swing trajectory to achieve welding process optimization with good surface forming. As shown in the figure, the method of the present invention includes the following steps S1 to S4.

[0163] S1, obtaining the relationship between the swing welding process parameters and the laser energy distribution characteristics and trajectory motion characteristics according to the swing laser beam parameters;

[0164] In the embodiment, the laser beam parameters include the laser radius r0; the process parameters include the laser power P, the welding speed v, the swing trajectory, the swing amplitude A, and the swing frequency f.

[0165] In this embodiment, a CFL-5000 laser produced by nLIGHT Corporation is used, and the beam diameter r0 is 0.1 mm.

[0166] In an embodiment, the laser trajectory motion characteristics include the geometry of the trajectory of the welding beam during the swinging process, the path length and the speed change characteristics thereof. By analyzing the influence of different swinging trajectories on the weld morphology and internal structure, the influence of the swinging trajectory on the energy distribution is determined.

[0167] In the embodiment of the present invention, a circular swing trajectory is used, and the motion equation of the circular swing trajectory is:

[0168]

[0169] By differentiating the equation of motion with respect to time, we can obtain the variation of the beam swing velocity component and the overall velocity with time, as shown in the following formula:

[0170]

[0171] Finally, input the set parameters and analyze the average speed and maximum speed of each trajectory to obtain the speed characteristics of the swing trajectory.

[0172] V 平均 =mean(V 合 )

[0173] V max =max(V 合 )

[0174] Laser energy distribution characteristics refer to the energy accumulation and distribution of the laser beam on the two-dimensional plane of the welding workpiece during the entire welding process. The main characteristic parameters include laser comprehensive linear energy density, laser transient linear energy density, and laser energy peak.

[0175] Assume that the laser beam is a planar heat source and the beam intensity conforms to an ideal Gaussian distribution.

[0176]

[0177] Integrating the light intensity formula over the entire time domain can yield the energy distribution in the entire two-dimensional plane during laser oscillation welding.

[0178]

[0179] The total energy input is

[0180]

[0181] Where m and n are the length of the weld in the x direction, and q and p are the width of the weld in the y direction. Laser comprehensive linear energy density E 0 Characterizes the uniformity of the overall heat input. Its physical meaning is the average energy absorbed per unit length of the track. The calculation formula is:

[0182]

[0183] Where L is the actual movement length of the light beam, and the calculation formula is:

[0184]

[0185] Laser transient linear energy density E i Characterize the local heat input, which is the actual energy absorbed by the unit length trajectory after combining the speed of the corresponding point of the beam swing trajectory, the beam action time and other factors. The calculation formula is:

[0186]

[0187] The energy peak reflects the value at which the energy accumulation on the two-dimensional plane of the workpiece is maximum after the welding process is completed.

[0188] I max =Max(E(x,y))

[0189] S2, establish the optimization constraint conditions of the energy distribution characteristics and motion characteristics of the laser oscillating welding beam;

[0190] A set of process parameters with the same swing amplitude and different swing frequencies are selected. The swing amplitude-swing frequency are 1.5mm-50Hz, 1.5mm-100Hz, 1.5mm-150Hz, 1.5mm-200Hz, and 1.5mm-250Hz respectively. When the swing frequency is 100Hz-200Hz, the weld surface is well formed and uniform. When the swing frequency is above 200Hz, defects such as spatter and undercut appear. At this time, the corresponding maximum speed V under this parameter is calculated according to the above motion speed characteristics. max =980mm / s, then it can be determined that the material and joint type correspond to V' max =980mm / s.

[0191] When the swing frequency is 100Hz-200Hz, the light integrated line energy density E corresponding to the parameters in this range is obtained according to the above energy distribution calculation formula. 0 Range and laser transient linear energy density Ei for

[0192] 9.534J / mm <E 0 <3.183J / mm

[0193] E i <3.101J / mm

[0194] Substitute the parameters into

[0195]

[0196] S3, obtaining a preset range of process parameters;

[0197] The process parameter range is roughly selected according to the upper and lower limits of the parameters that can be reached by the welding equipment and the specific joint requirements. In the embodiment, the swing welding joint can reach an adjustable range of swing amplitude of 0-5.0mm, and an adjustable range of swing frequency of 0-300Hz. In this way, the change range of the point laser power is roughly obtained as [Pmin, Pmax], the change range of the welding speed is [vmin, vmax], the change range of the laser swing amplitude is [Amin, Amax], and the change range of the laser swing frequency is [fmin, fmax].

[0198] The points in the above variation interval are gradually substituted into the above optimization constraints by interpolation. The parameter combination that satisfies all the above constraints is retained. Otherwise, this group of parameters is discarded and the verification calculation of the next group of parameters is performed. In this way, a better process parameter combination corresponding to the target melting depth can be screened out from the above rough selection range, and the optimal process parameters can be directly selected next time it is used. It is simple and convenient.

[0199] A set of parameters a was randomly selected: laser power of 3000W, welding speed of 25mm / s, swing amplitude of 2.0mm, and swing amplitude of 200Hz; a set of optimized experimental design parameters b was selected according to this patent application: laser power of 3000W, welding speed of 25mm / s, swing amplitude of 1.0mm, and swing amplitude of 250Hz, and the weld surface morphology is shown in the figure. The experimental results show that the surface forming of the process parameters optimized by this method is significantly better than the process parameters of the ordinary experimental design.

[0200] The above method steps only list the process of designing process parameters corresponding to achieving good surface forming of TA15 titanium alloy. In fact, the present invention is also applicable to the process design of other materials. For example, when the material is aluminum or steel, the method of the present invention is also applicable to various joint forms, such as lap joint, butt joint, and T-joint.

[0201] In summary, the present invention proposes a set of scientific and efficient process optimization schemes by constructing an optimization method and system for forming good process parameters in titanium alloy laser oscillating welding, combining the laser trajectory motion characteristics and energy distribution characteristics. This method aims to improve welding quality, stability and efficiency, effectively solves the problems of porosity, undercut, spatter, etc. existing in traditional welding, and significantly improves the uniformity and consistency of weld morphology and joint mechanical properties. At the same time, the present invention is based on theoretical analysis, gets rid of the dependence on a large number of experiments, and provides systematic and standardized guiding principles for parameter selection in engineering practice. This technical solution is suitable for the welding of various titanium alloy materials and complex structural parts, has wide applicability and strong engineering value, and provides solid technical support for the promotion and application of titanium alloy joints in high-end fields such as aerospace.

[0202] The relevant evidence of the technical effects obtained by the embodiments of the present invention is as follows:

[0203] The method of the present invention is used to optimize the process parameters of the swing welding test. The energy distribution axonometric diagram, side view and top view of the optimized process parameters are shown in Figure 1. Figure 4 , Figure 5 , Figure 6 As shown in the figure, it shows that the parameters are reasonably selected, which optimizes the energy distribution along the vertical direction of welding and reduces the negative impact of heat input on the welded joint. The surface shape of the joint obtained by randomly selecting welding process parameters before optimization is shown in the figure. Fig. 7A As shown in Figure 2, the spatter and undercut defects of the welded joint are serious, and blindly adjusting any parameter cannot eliminate the defects. The surface forming of the joint obtained after optimizing the welding process parameters is shown in Figure 2. Figure 7B As shown, the liquid metal is fully spread, there are no obvious surface defects, and the mechanical properties are greatly improved.

[0204] It should be noted that the embodiments of the present invention can be implemented by hardware, software, or a combination of software and hardware. The hardware part can be implemented using dedicated logic; the software part can be stored in a memory and executed by an appropriate instruction execution system, such as a microprocessor or dedicated design hardware. It can be understood by a person of ordinary skill in the art that the above-mentioned devices and methods can be implemented using computer executable instructions and / or contained in a processor control code, such as a carrier medium such as a disk, CD or DVD-ROM, a programmable memory such as a read-only memory (firmware), or a data carrier such as an optical or electronic signal carrier. Such code is provided on the carrier medium. The device and its modules of the present invention can be implemented by hardware circuits such as very large-scale integrated circuits or gate arrays, semiconductors such as logic chips, transistors, etc., or programmable hardware devices such as field programmable gate arrays, programmable logic devices, etc., can also be implemented by software executed by various types of processors, and can also be implemented by a combination of the above-mentioned hardware circuits and software, such as firmware.

[0205] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by any technician familiar with the technical field within the technical scope disclosed by the present invention and within the spirit and principle of the present invention should be covered by the protection scope of the present invention.

Claims

1. A titanium alloy skin-frame joint laser oscillation welding method, characterized in that: The titanium alloy skin-frame joint laser oscillation welding method comprises the following steps: S101, obtaining the relationship between the swing welding process parameters and the laser energy distribution characteristics and trajectory motion characteristics based on the swing laser beam parameters; S102, establishing optimization constraints for energy distribution characteristics and motion characteristics of the laser oscillating welding beam; obtaining a preset range of process parameters; S103, substituting the process parameter values ​​within the preset range into the optimization constraints of the energy distribution characteristics and motion characteristics of the laser oscillating welding beam, and then combining the process parameters that simultaneously satisfy the optimization constraints of the energy distribution characteristics and motion characteristics of the laser oscillating welding beam into the optimized process parameters.

2. The titanium alloy skin-frame joint laser oscillation welding method as claimed in claim 1, characterized in that: The laser beam parameter is the laser diameter d0; the process parameters include laser power P, welding speed v, swing trajectory, swing amplitude A, and swing frequency f; The laser trajectory motion characteristics include the geometric shape, path length and speed change characteristics of the welding beam trajectory during the swing process; by analyzing the influence of different swing trajectories on the weld morphology and internal structure, the influence of the swing trajectory on the energy distribution is determined; Taking the circular swing trajectory as an example, the motion equation of the circular swing trajectory is By differentiating the equation of motion with respect to time, we can obtain the variation of the beam swing velocity component and the overall velocity with time, as shown in the following formula: Finally, input the set parameters and analyze the average speed and maximum speed of each trajectory, then the speed distribution characteristics of the swing trajectory can be obtained. V 平均 =mean(V 合 ) V max =max(V 合 )。 3. The titanium alloy skin-frame joint laser oscillation welding method as claimed in claim 1, characterized in that: The optimization constraints of the motion features are: V max <980mm / s; The reason for limiting the minimum average speed is to ensure sufficient stirring effect, so that the molten pool liquid can be fully spread to form a uniform, straight weld with consistent molten width; the reason for limiting the maximum speed is to prevent the molten pool liquid from being accelerated to a critical speed and flying out of the molten pool from the rear end to form splash defects. At the same time, the increase in speed will also aggravate the unevenness of the swing welding liquid level, thereby forming an undercut defect, which becomes a weak point in mechanical properties.

4. The titanium alloy skin-frame joint laser oscillation welding method as claimed in claim 1, characterized in that: The laser energy distribution characteristics refer to the energy accumulation and distribution of the laser beam on the two-dimensional plane of the welding workpiece during the entire welding process; the main characteristic parameters include laser comprehensive linear energy density, laser transient linear energy density, and laser energy peak value; Assume that the laser beam is a planar heat source and the beam intensity conforms to an ideal Gaussian distribution. Integrating the light intensity formula over the entire time domain can yield the energy distribution in the entire two-dimensional plane during laser oscillation welding. The total energy input is Where m and n are the lengths of the weld in the x direction, and q and p are the widths of the weld in the y direction. The laser comprehensive linear energy density E0 represents the uniformity of the overall heat input. Its physical meaning is the average energy absorbed per unit length trajectory. The calculation formula is: Where L is the actual movement length of the light beam, and the calculation formula is: Laser transient linear energy density E i Characterize the local heat input, which is the actual energy absorbed by the unit length trajectory after combining factors such as the speed of the corresponding point of the beam swing trajectory and the beam action time. The calculation formula is: The energy peak reflects the value of the maximum accumulated energy on the two-dimensional plane of the workpiece after the welding process is completed: I max =Max(E(x,y))。 5. The titanium alloy skin-frame joint laser oscillation welding method as claimed in claim 1, characterized in that: The optimization constraint of the energy distribution is E i <3.101J / mm 9.534J / mm <E0<3.183J / mm The limiting principle for the comprehensive laser line energy density is to allow the heat to act on the workpiece plane to the greatest extent and most evenly, avoiding local overheating and other phenomena; the limiting principle for the instantaneous laser line energy density is to allow the laser input to maintain the heat level for the stable existence of the small holes in the molten pool, avoiding local instability due to insufficient heat, the periodic collapse of small holes, and the generation of defects such as pores, spatter, and depressions.

6. The titanium alloy skin-frame joint laser oscillation welding method as claimed in claim 1, characterized in that: The method for optimizing process parameters for good forming in titanium alloy oscillating laser welding: Obtaining a preset range of the process parameters according to the working range of each parameter of the welding system or the process requirements; The obtained process parameter interval is input into the optimization constraint conditions. When the process parameters satisfy both the energy distribution characteristic and the motion characteristic optimization constraint conditions, they are retained. Otherwise, they are discarded and the next set of process parameters are verified.

7. A titanium alloy skin-frame joint laser oscillation welding system for implementing the titanium alloy skin-frame joint laser oscillation welding method as described in any one of claims 1 to 6, characterized in that: The titanium alloy skin-frame joint laser oscillation welding system comprises: A feature acquisition module, used to acquire the relationship between the swing welding process parameters and the laser energy distribution characteristics and trajectory motion characteristics based on the swing laser beam parameters; The constraint condition establishment module is used to establish the optimization constraint conditions of the energy distribution characteristics and motion characteristics of the laser oscillating welding beam; and obtain the preset range of the process parameters; The optimization module is used to substitute the process parameter values ​​within a preset range into the optimization constraints of the energy distribution characteristics and motion characteristics of the laser oscillating welding beam, and then the process parameter combination that simultaneously satisfies the optimization constraints of the energy distribution characteristics and motion characteristics of the laser oscillating welding beam is the optimized process parameter.

8. A computer device, characterized in that: The computer device includes a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the steps of the titanium alloy skin-skeleton joint laser oscillation welding method as described in any one of claims 1-6.

9. A computer-readable storage medium storing a computer program, wherein when the computer program is executed by a processor, the processor executes the steps of the laser oscillating welding method for a titanium alloy skin-frame joint as claimed in any one of claims 1 to 6.

10. An information data processing terminal, characterized in that: The information data processing terminal is used to implement the titanium alloy skin-skeleton joint laser oscillation welding system as described in claim 7.

Images