A swing laser welding method for plates of unequal thickness

Abstract

The present application discloses a swing laser welding method for plates of unequal thickness, aiming to solve the technical problem that the welding quality of plates of unequal thickness in the existing swing laser welding method is poor; the method comprises the following steps: geometric modeling is performed based on the plates of unequal thickness to be welded to obtain a first simulation model of the plates of unequal thickness; based on the first simulation model of the plates of unequal thickness, a number of swing laser welding first parameters are formulated; based on the first simulation model of the plates of unequal thickness, laser welding is performed on the first simulation model of the plates of unequal thickness respectively to obtain a number of second simulation models of the plates of unequal thickness; based on the second simulation models of the plates of unequal thickness, simulated weld seam laser energy integral values ​​of the second simulation models of the plates of unequal thickness are respectively obtained; based on the simulated weld seam laser energy integral values, a number of simulated ratios of the weld seam laser energy integral values ​​are obtained; based on the simulation ratios of the laser energy integral values, a swing laser welding second parameter is obtained; based on the second swing laser welding parameter, laser welding is performed on the plates of unequal thickness to be welded.

Description

Technical Field

[0001] The present application relates to the field of laser welding manufacturing technology, and in particular to a swing laser welding method for plates of unequal thickness. Background Art

[0002] Welding of plates of unequal thickness is a common form of metal component connection in the aviation, aerospace, automotive and other industrial fields. The swing laser welding method uses the high-frequency galvanometer in the optical path system to swing the laser beam along a certain trajectory. During the welding process, it can swing on both sides of the seam between two plates of unequal thickness to adjust the proportion of laser energy absorbed by both sides, improve the welding quality, and avoid the problem of one side being welded through while the other side collapses. However, the existing swing laser welding method has poor welding quality for plates of unequal thickness. Summary of the invention

[0003] The main purpose of the present application is to provide a swing laser welding method for plates of unequal thickness, aiming to solve the technical problem of poor welding quality of plates of unequal thickness in the existing swing laser welding method.

[0004] In order to solve the above technical problems, the embodiment of the present application proposes: a swing laser welding method for plates of unequal thickness, comprising the following steps:

[0005] Based on the unequal thickness plates to be welded, geometric modeling is performed to obtain a first simulation model of the unequal thickness plates; based on the first simulation model of the unequal thickness plates, a number of first swing laser welding parameters are formulated; wherein the first swing laser welding parameters include at least one of a laser radius, a laser power, a welding speed, a swing form of a laser head, a swing amplitude of a laser head, and a swing frequency of a laser head;

[0006] Based on the first swing laser welding parameters, the first simulation models of plates with different thicknesses are respectively subjected to simulated laser welding to obtain the second simulation models of plates with different thicknesses;

[0007] Based on the plurality of second simulation models of plates of unequal thickness, respectively obtaining the simulated weld laser energy integral values ​​of the plurality of second simulation models of plates of unequal thickness;

[0008] Based on the plurality of simulated weld seam laser energy integral values, obtaining a plurality of simulated ratios of the weld seam laser energy integral values; based on the plurality of simulated ratios of the laser energy integral values, obtaining a second parameter of the swing laser welding;

[0009] Based on the second swing laser welding parameter, laser welding is performed on the plates of unequal thickness to be welded.

[0010] As some possible implementation methods of the present application, based on the plurality of second simulation models of plates of unequal thickness, respectively obtaining the simulated weld laser energy integral values ​​of the plurality of second simulation models of plates of unequal thickness, comprises:

[0011] The welds of the second simulation model of the plates of unequal thickness are divided into square grids of equal size, and the integral value of the simulated weld laser energy absorbed by each grid at time t is calculated.

[0012] As some possible implementation methods of the present application, the simulated weld laser energy integral value is obtained by the following relationship:

[0013]

[0014] Among them, Q(x,y) represents the integrated value of the laser energy of the simulated weld; t represents the time when welding starts; t1 represents the time when welding ends; q(x,y,t) represents the energy density value of the laser beam absorbed by the metal plate in the weld at time t; dx represents the size of the square grid in the x direction; dy represents the size of the square grid in the y direction; dt represents the time step; y<0 represents the area of ​​metal plate A in the weld, and y>0 represents the area of ​​metal plate B in the weld.

[0015] As some possible implementation methods of the present application, the energy density value of the laser beam absorbed once by the metal plate in the weld at time t is obtained by the following relationship:

[0016]

[0017] Wherein, q(x, y, t) represents the energy density value of the laser beam absorbed by the metal plate in the weld at time t; (x, y) represents the coordinates of the metal plate in the weld, (x l ,y l ) represents the coordinate of the center point of the laser beam at time l, P represents the laser power, R represents the radius of the laser beam, and η represents the laser energy absorption coefficient of the metal plate in the weld.

[0018] As some possible implementation methods of the present application, the movement form of the center point of the laser beam is the combined movement of the swing of the laser head and the linear movement in the welding direction;

[0019] When the welding direction is along the x-axis, the laser center coordinates are obtained by the following relationship:

[0020]

[0021] Among them, (x l ,y l ) represents the coordinates of the center point of the laser beam at time 1, (x0, y0) represents the initial coordinates of the center point of the laser beam, x(t) represents the swing motion value of the laser head in the x direction, y(t) represents the swing motion value of the laser head in the y direction, v represents the welding speed, and t represents the time.

[0022] As some possible implementation methods of the present application, the swing motion values ​​of the laser head in the x-direction and the y-direction are related to the swing form of the laser head, wherein the swing form of the laser head includes at least one of sinusoidal swing, circular swing and lateral linear swing.

[0023] As some possible implementation methods of the present application, when the swing form of the laser head is a sinusoidal swing, the swing motion values ​​of the laser head in the x direction and the y direction are obtained by the following relationship:

[0024]

[0025] Wherein, x(t) represents the swing motion value of the laser head in the x direction, y(t) represents the swing motion value of the laser head in the y direction, f represents the swing frequency of the laser head, A represents the swing amplitude of the laser head in the y direction, B represents the swing amplitude of the laser head in the x direction, and t represents the swing time value of the laser head.

[0026] As some possible implementation methods of the present application, when the swing form of the laser head is a circular swing, the swing motion values ​​of the laser head in the x direction and the y direction are obtained by the following relationship:

[0027]

[0028] Wherein, x(t) represents the swing motion value of the laser head in the x direction, y(t) represents the swing motion value of the laser head in the y direction, f represents the swing frequency of the laser head, A represents the swing amplitude of the laser head in the y direction, and t represents the swing time value of the laser head.

[0029] As some possible implementation methods of the present application, when the swing form of the laser head is a horizontal linear swing, the swing motion values ​​of the laser head in the x direction and the y direction are obtained by the following relationship:

[0030]

[0031] Wherein, x(t) represents the swing motion value of the laser head in the x direction, y(t) represents the swing motion value of the laser head in the y direction, A represents the swing amplitude of the laser head in the y direction, f represents the swing frequency of the laser head, t represents the swing time value of the laser head, and n is a multiple of the period.

[0032] As some possible implementation methods of the present application, based on the plurality of simulated weld laser energy integral values, obtaining a plurality of weld laser energy integral value simulation ratios; taking the plurality of laser energy integral value ratios to obtain the swing laser welding second parameter, comprises:

[0033] Based on the plurality of simulated weld seam laser energy integral values, obtaining a plurality of simulated weld seam laser energy integral value simulation ratios;

[0034] A number of laser energy integral value ratios are compared, and the first swing laser welding parameter corresponding to the laser energy integral value ratio closest to 1 is selected and used as the second swing laser welding parameter.

[0035] As some possible implementation methods of the present application, the simulated ratio of the weld laser energy integral value is obtained by the following relationship:

[0036]

[0037] Among them, σ represents the simulation ratio of the integral value of laser energy of the weld, Q1 represents the integral value of laser energy absorbed by the thinner plate in the weld, V1 represents the volume value of the weld area of ​​the thinner plate in the weld, Q2 represents the integral value of laser energy absorbed by the thicker plate in the weld, and V2 represents the volume value of the weld area of ​​the thicker plate in the weld.

[0038] Compared with the prior art, the method described in the embodiment of the present application obtains a first simulation model of plates of unequal thickness by geometric modeling based on plates of unequal thickness to be welded; based on the first simulation model of plates of unequal thickness, a number of first swinging laser welding parameters, i.e., initial welding parameters, are formulated, and the initial welding parameters include a number of groups. The initial welding parameters in the groups can be subjected to orthogonal tests to reduce the number of process parameter groups, thereby improving the test efficiency; then, based on the first swinging laser welding parameters, simulated laser welding is performed on the first simulation model of plates of unequal thickness to obtain a number of second simulation models of plates of unequal thickness; based on the second simulation models of plates of unequal thickness, simulated weld laser energy integral values ​​of the second simulation models of plates of unequal thickness are obtained respectively; based on the simulated weld laser energy integral values, a number of simulated ratios of the weld laser energy integral values ​​are obtained; the simulated ratios of the weld laser energy integral values ​​are compared, and the initial parameters corresponding to the appropriate ratios are selected as the second swinging laser welding parameters, and the plates of unequal thickness are laser welded according to the second swinging laser welding parameters. The above-mentioned welding of plates of unequal thickness is a common form of connection of metal components in the aviation, aerospace, automobile and other industrial fields, and laser welding technology has great application potential in the field of welding of plates of unequal thickness due to its advantages of high welding efficiency, high precision, low heat input, and good accessibility. However, since the two plates of unequal thickness have different thermal conductivity characteristics, it is necessary to accurately control the energy on both sides during welding to avoid problems such as the thick plate side being welded through and the thin plate side collapsing. The existing laser welding technology is difficult to control the energy distribution of the two sides due to the small radius of the laser spot, and it is difficult to control the welding quality of plates of unequal thickness. Based on the above-mentioned technical problems, the method described in the present application simulates and models the absorption of swinging laser energy by plates of unequal thickness under different process parameters and compares them, determines the optimal process parameters based on the comparison results, and performs swinging laser welding on the plates of unequal thickness according to the obtained process parameters, thereby improving the welding quality of plates of unequal thickness. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 Schematic diagram of the steps of the swing laser welding method for plates of unequal thickness described in the embodiment of the present application;

[0040] Figure 2 This is a diagram of energy distribution simulation results of circular swing laser welding when the initial offset distance is 0.1 mm as described in Example 1 of the present application;

[0041] Figure 3 This is a diagram of energy distribution simulation results of circular swing laser welding when the initial offset distance is 0.3 mm as described in Example 1 of the present application;

[0042] Figure 4This is a diagram of energy distribution simulation results of circular swing laser welding when the initial offset distance is 0.5 mm as described in Example 1 of the present application;

[0043] Figure 5 This is a diagram of the energy distribution simulation result of the transverse linear oscillating laser welding when the initial oscillation frequency is 10 Hz as described in Example 2 of the present application;

[0044] Figure 6 This is a diagram of the energy distribution simulation result of the transverse linear oscillating laser welding when the initial oscillation frequency is 30 Hz as described in Example 2 of the present application;

[0045] Figure 7 This is a diagram of the energy distribution simulation results of transverse linear oscillation laser welding when the initial oscillation frequency is 50 Hz as described in Example 2 of the present application. DETAILED DESCRIPTION

[0046] It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0047] Welding of plates of unequal thickness is a common form of metal component connection in the aviation, aerospace, automotive and other industrial fields. The swing laser welding method uses the high-frequency galvanometer in the optical path system to swing the laser beam along a certain trajectory. During the welding process, it can swing on both sides of the seam between two plates of unequal thickness to adjust the proportion of laser energy absorbed by both sides, improve the welding quality, and avoid the problem of one side being welded through while the other side collapses. However, the existing swing laser welding method has poor welding quality for plates of unequal thickness.

[0048] Therefore, based on the above technical issues, Figure 1 As shown, the embodiment of the present application proposes: a swing laser welding method for plates of unequal thickness, comprising the following steps:

[0049] Step S10, based on the unequal thickness plates to be welded, geometric modeling is performed to obtain a first simulation model of the unequal thickness plates; based on the first simulation model of the unequal thickness plates, a number of oscillating laser welding first parameters are formulated; wherein the oscillating laser welding first parameters include at least one of the laser radius, laser power, welding speed, oscillation form of the laser head, oscillation amplitude of the laser head and oscillation frequency of the laser head.

[0050] In a specific application, when geometric modeling is performed on the plates of unequal thickness to be welded, the geometric dimensions and material properties of the plates of unequal thickness need to be confirmed first. The geometric dimensions include the thickness, length and width of the two plates of unequal thickness, and the material properties include the absorptivity, density, specific heat capacity and thermal conductivity of the material to the laser. The geometric modeling is performed using general geometric modeling software (such as UG, Catia, etc.). In a specific application, the swing form of the laser head includes at least one of sinusoidal swing, circular swing and transverse linear swing.

[0051] Step S20: Based on the plurality of first swing laser welding parameters, simulated laser welding is performed on the first simulation models of plates of unequal thickness respectively to obtain a plurality of second simulation models of plates of unequal thickness.

[0052] In a specific application, the first simulation model of unequal thickness plates is simulated by laser welding based on the first swing laser welding parameter, aiming to simulate the absorption of laser energy by two unequal thickness plates in the first simulation model of unequal thickness plates during the swing laser welding process, and the second simulation model of unequal thickness plates is obtained after the laser welding is completed. Since the first swing laser welding parameter includes several parameters, wherein the parameter types include at least one of the laser radius, laser power, welding speed, the swing form of the laser head, the swing amplitude of the laser head and the swing frequency of the laser head, and each type includes several groups; therefore, in order to reduce the number of test groups, the embodiment of the present application conducts orthogonal tests on the several parameters.

[0053] Step S30: based on the plurality of second simulation models of plates of unequal thickness, respectively obtain the simulated weld laser energy integral values ​​of the plurality of second simulation models of plates of unequal thickness.

[0054] In a specific application, step S30 includes: dividing the welds of the second simulation model of the plates of unequal thickness into square grids of equal size, and calculating the integral value of the simulated weld laser energy absorbed by each grid at time t. The above steps can be implemented by computer programming, including but not limited to matlab, C++, C language, python language, etc.

[0055] Specifically, the simulated weld laser energy integral value is obtained by the following relationship:

[0056]

[0057] Among them, Q(x,y) represents the integrated value of the laser energy of the simulated weld; t represents the time when welding starts; t1 represents the time when welding ends; q(x,y,t) represents the energy density value of the laser beam absorbed by the metal plate in the weld at time t; dx represents the size of the square grid in the x direction; dy represents the size of the square grid in the y direction; dt represents the time step; y<0 represents the area of ​​metal plate A in the weld, and y>0 represents the area of ​​metal plate B in the weld.

[0058] Specifically, the energy density value of the laser beam absorbed by the metal plate in the weld at time t is obtained by the following relationship:

[0059]

[0060] Wherein, q(x, y, t) represents the energy density value of the laser beam absorbed by the metal plate in the weld at time t; (x, y) represents the coordinates of the metal plate in the weld, (x l ,y l ) represents the coordinate of the center point of the laser beam at time l, P represents the laser power, R represents the radius of the laser beam, and η represents the laser energy absorption coefficient of the metal plate in the weld.

[0061] Specifically, the movement form of the center point of the laser beam is the combined movement of the swing of the laser head and the linear movement in the welding direction;

[0062] When the welding direction is along the x-axis, the laser center coordinates are obtained by the following relationship:

[0063]

[0064] Among them, (x l ,y l ) represents the coordinates of the center point of the laser beam at time 1, (x0, y0) represents the initial coordinates of the center point of the laser beam, x(t) represents the swing motion value of the laser head in the x direction, y(t) represents the swing motion value of the laser head in the y direction, v represents the welding speed, and t represents the time.

[0065] In a specific application, the swing motion values ​​of the laser head in the x-direction and the y-direction are related to the swing form of the laser head, wherein the swing form of the laser head includes at least one of sinusoidal swing, circular swing and transverse linear swing. Specifically, when the swing form of the laser head is sinusoidal swing, the swing motion values ​​of the laser head in the x-direction and the y-direction are obtained by the following relationship:

[0066]

[0067] Wherein, x(t) represents the swing motion value of the laser head in the x direction, y(t) represents the swing motion value of the laser head in the y direction, f represents the swing frequency of the laser head, A represents the swing amplitude of the laser head in the y direction, B represents the swing amplitude of the laser head in the x direction, and t represents the swing time value of the laser head.

[0068] Specifically, when the swing form of the laser head is circular swing, the swing motion values ​​of the laser head in the x direction and the y direction are obtained by the following relationship:

[0069]

[0070] Wherein, x(t) represents the swing motion value of the laser head in the x direction, y(t) represents the swing motion value of the laser head in the y direction, f represents the swing frequency of the laser head, A represents the swing amplitude of the laser head in the y direction, and t represents the swing time value of the laser head.

[0071] Specifically, when the swing form of the laser head is a horizontal linear swing, the swing motion values ​​of the laser head in the x direction and the y direction are obtained by the following relationship:

[0072]

[0073] Wherein, x(t) represents the swing motion value of the laser head in the x direction, y(t) represents the swing motion value of the laser head in the y direction, A represents the swing amplitude of the laser head in the y direction, f represents the swing frequency of the laser head, t represents the swing time value of the laser head, and n is a multiple of the period.

[0074] Step S40, based on the plurality of simulated weld laser energy integral values, obtaining a plurality of simulated ratios of the weld laser energy integral values; based on the plurality of simulated ratios of the laser energy integral values, obtaining a second parameter of the swing laser welding.

[0075] In a specific application, the step S40 includes: based on a number of the simulated weld laser energy integral values, obtaining a number of simulated ratios of the weld laser energy integral values; comparing the ratios of the laser energy integral values, and selecting the first swinging laser welding parameter corresponding to the laser energy integral value ratio closest to 1, and using it as the second swinging laser welding parameter.

[0076] Specifically, the above steps are mainly to compare the energy values ​​absorbed by the unit volume of metal on both sides of the weld to ensure that the welding quality of plates of unequal thickness is close and to ensure the melting effect of the two plates of unequal thickness, that is, the thicker plate absorbs more energy and the thinner plate absorbs less energy, but the energy absorbed by the unit volume of metal in the weld area of ​​the two plates is similar; therefore, after the laser energy integral value is ratio-processed, the first oscillating laser welding parameter corresponding to the laser energy integral value ratio closest to 1 is selected and used as the second oscillating laser welding parameter.

[0077] Specifically, the simulation ratio of the weld laser energy integral value is obtained by the following relationship:

[0078]

[0079] Among them, σ represents the simulation ratio of the integral value of laser energy of the weld, Q1 represents the integral value of laser energy absorbed by the thinner plate in the weld, V1 represents the volume value of the weld area of ​​the thinner plate in the weld, Q2 represents the integral value of laser energy absorbed by the thicker plate in the weld, and V2 represents the volume value of the weld area of ​​the thicker plate in the weld.

[0080] Specifically, the welding process of plates of different thickness generally has specific requirements for the weld morphology. The weld area volumes V1 and V2 are determined according to the welding requirements. For example, the weld length is L, the width of the thin plate side is W1, the depth is H1, and the width of the thick plate side is W2, the depth is H2, where the welding depth of the thin plate side is equal to the thickness of the thin plate, and the welding depth of the thick plate is greater than the thickness of the thin plate. To determine whether the process parameters are feasible, it is necessary to ensure that the energy absorbed by the metal on both sides is similar. The ideal state is σ = 1, but there is a certain deviation in the actual laser welding process. Therefore, σ values ​​between 0.6 and 1.4 can meet the welding requirements.

[0081] Step S50: Based on the second swing laser welding parameter, laser welding is performed on the plates of unequal thickness to be welded.

[0082] The unequal thickness plates obtained by laser welding using the second oscillating laser welding parameter can effectively avoid problems such as full penetration on one side of the thick plate and collapse on the other side of the thin plate due to the precise control of the energy on both sides, thus significantly improving the welding quality of the unequal thickness plates.

[0083] Compared with the prior art, the method described in the embodiment of the present application obtains a first simulation model of plates of unequal thickness by geometric modeling based on plates of unequal thickness to be welded; based on the first simulation model of plates of unequal thickness, a number of first swinging laser welding parameters, i.e., initial welding parameters, are formulated, and the initial welding parameters include a number of groups. The initial welding parameters in the groups can be subjected to orthogonal tests to reduce the number of process parameter groups, thereby improving the test efficiency; then, based on the first swinging laser welding parameters, simulated laser welding is performed on the first simulation model of plates of unequal thickness to obtain a number of second simulation models of plates of unequal thickness; based on the second simulation models of plates of unequal thickness, simulated weld laser energy integral values ​​of the second simulation models of plates of unequal thickness are obtained respectively; based on the simulated weld laser energy integral values, a number of simulated ratios of the weld laser energy integral values ​​are obtained; the simulated ratios of the weld laser energy integral values ​​are compared, and the initial parameters corresponding to the appropriate ratios are selected as the second swinging laser welding parameters, and the plates of unequal thickness are laser welded according to the second swinging laser welding parameters. The above-mentioned welding of plates of unequal thickness is a common form of connection of metal components in the aviation, aerospace, automobile and other industrial fields, and laser welding technology has great application potential in the field of welding of plates of unequal thickness due to its advantages of high welding efficiency, high precision, low heat input, and good accessibility. However, since the two plates of unequal thickness have different thermal conductivity characteristics, it is necessary to accurately control the energy on both sides during welding to avoid problems such as the thick plate side being welded through and the thin plate side collapsing. The existing laser welding technology is difficult to control the energy distribution of the two sides due to the small radius of the laser spot, and it is difficult to control the welding quality of plates of unequal thickness. Based on the above-mentioned technical problems, the method described in the present application simulates and models the absorption of swinging laser energy by plates of unequal thickness under different process parameters and compares them, determines the optimal process parameters based on the comparison results, and performs swinging laser welding on the plates of unequal thickness according to the obtained process parameters, thereby improving the welding quality of plates of unequal thickness.

[0084] Below, the present application will describe in detail the swing laser welding method for plates of unequal thickness described in the present application in combination with specific implementation methods:

[0085] Example 1

[0086] This embodiment aims to simulate the energy distribution of circular swing laser welding under different offset distance parameters, that is, to set the initial offset distance parameters to 0.1mm, 0.3mm and 0.5mm respectively, and then obtain the optimal swing laser welding parameters according to the method described in this application.

[0087] Step 1: Determine the geometric dimensions and material properties of the unequal thickness plate welding and perform geometric modeling. The geometric dimensions of the unequal thickness plates are 200×100×5mm. 3and 200×100×3mm 3 UG software is used for geometric modeling. The material is 6061 aluminum alloy, and the laser absorption rate of the material is η=0.3.

[0088] Step 2: Preliminary formulation of the swing laser welding process plan, the swing laser welding form is a circular swing form, the specific parameters are laser power P = 2kW, welding speed v = 1.2m / min, laser radius R = 0.2mm, swing frequency f = 30Hz, swing amplitude A = 1mm. Thick plate melting requires more energy, and the laser beam needs to be offset in the direction of the thick plate by a certain distance, which is initially set to 0.1mm, 0.3mm, and 0.5mm respectively. The preferred offset distance parameter, that is, the initial laser coordinate y0, is determined by this method.

[0089] Step 3: According to the circular swing form and welding parameters, determine the swing laser welding energy simulation calculation relationship, that is:

[0090] The simulated weld laser energy integral value is obtained by the following relationship:

[0091]

[0092] Among them, Q(x,y) represents the integrated value of the laser energy of the simulated weld; t represents the time when welding starts; t1 represents the time when welding ends; q(x,y,t) represents the energy density value of the laser beam absorbed by the metal plate in the weld at time t; dx represents the size of the square grid in the x direction; dy represents the size of the square grid in the y direction; dt represents the time step; y<0 represents the area of ​​metal plate A in the weld, and y>0 represents the area of ​​metal plate B in the weld.

[0093] In this embodiment, dx=dy=0.05 mm, dt=1 ms.

[0094] The energy density value of the laser beam absorbed by the metal plate in the weld at time t is obtained by the following relationship:

[0095]

[0096] Wherein, q(x, y, t) represents the energy density value of the laser beam absorbed by the metal plate in the weld at time t; (x, y) represents the coordinates of the metal plate in the weld, (x l ,y l ) represents the coordinate of the center point of the laser beam at time l, P represents the laser power, R represents the radius of the laser beam, and η represents the laser energy absorption coefficient of the metal plate in the weld.

[0097] The movement form of the center point of the laser beam is the combined movement of the swing of the laser head and the linear movement in the welding direction;

[0098] When the welding direction is along the x-axis, the laser center coordinates are obtained by the following relationship:

[0099]

[0100] Among them, (x l ,y l ) represents the coordinates of the center point of the laser beam at time 1, (x0, y0) represents the initial coordinates of the center point of the laser beam, x(t) represents the swing motion value of the laser head in the x direction, y(t) represents the swing motion value of the laser head in the y direction, v represents the welding speed, and t represents the time.

[0101] The swing motion values ​​of the laser head in the x-direction and the y-direction are obtained by the following relationship:

[0102]

[0103] Wherein, x(t) represents the swing motion value of the laser head in the x direction, y(t) represents the swing motion value of the laser head in the y direction, f represents the swing frequency of the laser head, A represents the swing amplitude of the laser head in the y direction, and t represents the swing time value of the laser head.

[0104] Step 4: Compare the energy distribution under different process parameter groups to determine the optimized process parameter range. The simulation ratio of the weld laser energy integral value is obtained according to the following formula:

[0105]

[0106] Among them, σ represents the simulation ratio of the integral value of laser energy of the weld, Q1 represents the integral value of laser energy absorbed by the thinner plate in the weld, V1 represents the volume value of the weld area of ​​the thinner plate in the weld, Q2 represents the integral value of laser energy absorbed by the thicker plate in the weld, and V2 represents the volume value of the weld area of ​​the thicker plate in the weld.

[0107] The calculated σ is equal to 1.2, 0.9 and 0.4 respectively. The energy distribution simulation results of circular swing laser welding at different offset distances in this embodiment are as follows: Figure 2-Figure 4 As shown, Figure 2 The initial offset distance is 0.1mm. Figure 3 The initial offset distance is 0.3mm. Figure 4 The initial offset distance is 0.5 mm. According to the selection standard of σ value, the laser welding parameters corresponding to σ=0.9 are selected to perform laser welding on plates of different thickness.

[0108] Example 2

[0109] This embodiment aims to simulate the energy distribution of horizontal vertical swing laser welding under different swing frequency parameters, that is, to set the initial swing frequency parameters to 10Hz, 30Hz and 50Hz respectively, and then obtain the optimal swing laser welding parameters according to the method described in this application.

[0110] Step 1: Determine the geometric dimensions and material properties of the unequal thickness plate welding and perform geometric modeling. The geometric dimensions of the unequal thickness plates are 200×100×5mm. 3 and 200×100×3mm 3 UG software is used for geometric modeling. The material is TC4 titanium alloy, and the laser absorption rate of the material is 0.35.

[0111] Step 2: Preliminary formulation of the swing laser welding process plan, swing laser welding is a horizontal linear swing form, the specific parameters are laser power P = 2kW, welding speed v = 1.2m / min, laser radius R = 0.2mm, swing amplitude A = 1mm, the laser beam needs to be offset in the direction of the thick plate by y0 = 0.3mm. In order to determine the appropriate swing frequency, this method is used to compare the laser energy distribution effects at different frequencies (f = 10Hz, f = 30Hz, f = 50Hz) to optimize the parameters.

[0112] Step 3: Determine the energy simulation calculation of the swing laser welding based on the transverse linear swing form and parameters, namely:

[0113] The simulated weld laser energy integral value is obtained by the following relationship:

[0114]

[0115] Among them, Q(x,y) represents the integrated value of the laser energy of the simulated weld; t represents the time when welding starts; t1 represents the time when welding ends; q(x,y,t) represents the energy density value of the laser beam absorbed by the metal plate in the weld at time t; dx represents the size of the square grid in the x direction; dy represents the size of the square grid in the y direction; dt represents the time step; y<0 represents the area of ​​metal plate A in the weld, and y>0 represents the area of ​​metal plate B in the weld.

[0116] In this embodiment, dx=dy=0.05 mm, and dt=1 ms.

[0117] The energy density value of the laser beam absorbed by the metal plate in the weld at time t is obtained by the following relationship:

[0118]

[0119] Wherein, q(x, y, t) represents the energy density value of the laser beam absorbed by the metal plate in the weld at time t; (x, y) represents the coordinates of the metal plate in the weld, (x l ,y l ) represents the coordinate of the center point of the laser beam at time l, P represents the laser power, R represents the radius of the laser beam, and η represents the laser energy absorption coefficient of the metal plate in the weld.

[0120] The motion form of the center point of the laser beam is the combined motion of the swing of the laser head and the linear motion in the welding direction; when the welding direction is along the x-axis, the laser center coordinates are obtained by the following relationship:

[0121]

[0122] Among them, (x l ,y l ) represents the coordinates of the center point of the laser beam at time 1, (x0, y0) represents the initial coordinates of the center point of the laser beam, x(t) represents the swing motion value of the laser head in the x direction, y(t) represents the swing motion value of the laser head in the y direction, v represents the welding speed, and t represents the time.

[0123] The swing motion values ​​of the laser head in the x-direction and the y-direction are obtained by the following relationship:

[0124]

[0125] Wherein, x(t) represents the swing motion value of the laser head in the x direction, y(t) represents the swing motion value of the laser head in the y direction, A represents the swing amplitude of the laser head in the y direction, f represents the swing frequency of the laser head, t represents the swing time value of the laser head, and n is a multiple of the period.

[0126] Step 4: Compare the energy distribution under different process parameter groups to determine the optimized process parameter range. The simulation ratio of the weld laser energy integral value is obtained according to the following formula:

[0127]

[0128] Among them, σ represents the simulation ratio of the integral value of laser energy of the weld, Q1 represents the integral value of laser energy absorbed by the thinner plate in the weld, V1 represents the volume value of the weld area of ​​the thinner plate in the weld, Q2 represents the integral value of laser energy absorbed by the thicker plate in the weld, and V2 represents the volume value of the weld area of ​​the thicker plate in the weld.

[0129] The calculated σ is equal to 1.8, 1.4 and 0.8 respectively. The energy distribution simulation results of the transverse linear swing laser welding at different offset distances in this embodiment are as follows: Figure 5-Figure 7 As shown, Figure 5 The initial oscillation frequency is 10Hz. Figure 6 The initial oscillation frequency is 30Hz. Figure 7 The initial oscillation frequency is 50 Hz. According to the selection standard of σ value, the laser welding parameters corresponding to σ=0.8 are selected to perform laser welding on plates of different thickness.

[0130] It can be seen from the above embodiments that the method described in this application is different from the prior art. It simulates the plates of different thicknesses after determining their size and material properties, and then uses the simulation model to determine different laser welding parameters. After orthogonal tests are conducted on multiple sets of parameters, the welding energy is calculated based on the completed simulation model, and then the optimal welding process parameters are determined based on the welding energy calculation results of the simulation model. Compared with the prior art, it not only effectively reduces the cost and cycle of process trial and error, but also effectively avoids the problem of unreasonable energy distribution on both sides during welding of plates of different thicknesses, resulting in one side being welded through and the other side collapsing.

[0131] The above are only preferred embodiments of the present application, and are not intended to limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A swing laser welding method for plates of unequal thickness, characterized in that: The following steps are involved: Based on the unequal thickness plates to be welded, geometric modeling is performed to obtain a first simulation model of the unequal thickness plates; based on the first simulation model of the unequal thickness plates, a number of first swing laser welding parameters are formulated; wherein the first swing laser welding parameters include at least one of a laser radius, a laser power, a welding speed, a swing form of a laser head, a swing amplitude of a laser head, and a swing frequency of a laser head; Based on the first swing laser welding parameters, the first simulation models of plates with different thicknesses are respectively subjected to simulated laser welding to obtain the second simulation models of plates with different thicknesses; Based on the plurality of second simulation models of plates of unequal thickness, respectively obtaining the simulated weld laser energy integral values ​​of the plurality of second simulation models of plates of unequal thickness; Based on the plurality of simulated weld laser energy integral values, a plurality of weld laser energy integral value simulation ratios are obtained; based on the plurality of simulated laser energy integral value simulation ratios, a second swing laser welding parameter is obtained; Based on the second swing laser welding parameter, laser welding is performed on the plates of unequal thickness to be welded; The simulated weld laser energy integral value is obtained by the following relationship: Wherein, Q(x,y) represents the integrated value of the laser energy of the simulated weld; t represents the time when welding starts; t1 represents the time when welding ends; q(x,y,t) represents the energy density value of the laser beam absorbed by the metal plate in the weld at time t; dx represents the size of the square grid in the x direction; dy represents the size of the square grid in the y direction; dt represents the time step; y<0 represents the area of ​​metal plate A in the weld, and y>0 represents the area of ​​metal plate B in the weld; The energy density value of the laser beam absorbed by the metal plate in the weld at time t is obtained by the following relationship: Wherein, q(x, y, t) represents the energy density value of the laser beam absorbed by the metal plate in the weld at time t; (x, y) represents the coordinates of the metal plate in the weld, (xl, yl) represents the coordinates of the center point of the laser beam at time l, P represents the laser power, R represents the radius of the laser beam, and η represents the laser energy absorption coefficient of the metal plate in the weld; The motion form of the center point of the laser beam is the combined motion of the swing of the laser head and the linear motion in the welding direction; when the welding direction is along the x-axis, the laser center coordinates are obtained by the following relationship: Wherein, (xl, yl) represents the coordinates of the center point of the laser beam at time l, (x0, y0) represents the initial coordinates of the center point of the laser beam, x(t) represents the swing motion value of the laser head in the x direction, y(t) represents the swing motion value of the laser head in the y direction, v represents the welding speed, and t represents the time; The swing motion values ​​of the laser head in the x-direction and the y-direction are related to the swing form of the laser head, wherein the swing form of the laser head includes at least one of sinusoidal swing, circular swing and transverse linear swing; The method comprises: obtaining a plurality of simulated weld laser energy integral values ​​based on the plurality of simulated weld laser energy integral values; obtaining a second swing laser welding parameter by using the simulated laser energy integral value ratios, including: obtaining a plurality of simulated weld laser energy integral value ratios based on the plurality of simulated weld laser energy integral values; comparing the plurality of simulated laser energy integral value ratios, selecting a first swing laser welding parameter corresponding to a laser energy integral value ratio closest to 1, and using the first swing laser welding parameter as a second swing laser welding parameter; The weld seam laser energy integral value simulation ratio is obtained by the following relationship: Among them, σ represents the simulation ratio of the integral value of laser energy of the weld, Q1 represents the integral value of laser energy absorbed by the thinner plate in the weld, V1 represents the volume value of the weld area of ​​the thinner plate in the weld, Q2 represents the integral value of laser energy absorbed by the thicker plate in the weld, and V2 represents the volume value of the weld area of ​​the thicker plate in the weld.

2. The swing laser welding method for plates of unequal thickness according to claim 1, characterized in that: The step of obtaining the simulated weld laser energy integral values ​​of the plurality of second simulation models of the plates of unequal thickness respectively based on the plurality of second simulation models of the plates of unequal thickness comprises: The welds of the second simulation model of the plates of unequal thickness are divided into square grids of equal size, and the integral value of the simulated weld laser energy absorbed by each grid at time t is calculated.

3. The swing laser welding method for plates of unequal thickness according to claim 1 is characterized in that: When the swing form of the laser head is sinusoidal swing, the swing motion values ​​of the laser head in the x direction and the y direction are obtained by the following relationship: Wherein, x(t) represents the swing motion value of the laser head in the x direction, y(t) represents the swing motion value of the laser head in the y direction, f represents the swing frequency of the laser head, A represents the swing amplitude of the laser head in the y direction, B represents the swing amplitude of the laser head in the x direction, and t represents the swing time value of the laser head.

4. The swing laser welding method for plates of unequal thickness according to claim 1 is characterized in that: When the swing form of the laser head is circular swing, the swing motion values ​​of the laser head in the x direction and the y direction are obtained by the following relationship: Wherein, x(t) represents the swing motion value of the laser head in the x direction, y(t) represents the swing motion value of the laser head in the y direction, f represents the swing frequency of the laser head, A represents the swing amplitude of the laser head in the y direction, and t represents the swing time value of the laser head.

5. The swing laser welding method for plates of unequal thickness according to claim 1, characterized in that: When the swing form of the laser head is a horizontal linear swing, the swing motion values ​​of the laser head in the x direction and the y direction are obtained by the following relationship: Wherein, x(t) represents the swing motion value of the laser head in the x direction, y(t) represents the swing motion value of the laser head in the y direction, A represents the swing amplitude of the laser head in the y direction, f represents the swing frequency of the laser head, t represents the swing time value of the laser head, and n is a multiple of the period.

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