Sheet metal assembly, sheet metal welding method and vehicle

Abstract

The invention discloses a metal plate assembly, a metal plate welding method and a vehicle. The sheet metal assembly comprises at least two sheet metal parts and a laser welding structure. The at least two sheet metal parts are stacked in the vertical direction, the sheet metal gap between every two adjacent sheet metal parts is smaller than a first threshold value, the first threshold value is the product of the thickness of the sheet metal part on the uppermost layer and a first coefficient, and the value range of the first coefficient is [0.2, 0.4]; the laser welding structure comprises a first welding structure and / or a second welding structure, the first welding structure is a welding structure which does not penetrate through the lowermost sheet metal part in the vertical direction, and the second welding structure is a welding structure which penetrates through the lowermost sheet metal part in the vertical direction. In the production process of the metal plate assembly, it is guaranteed that the metal plate gap meets the laser welding requirement, the laser welding technology is adopted for welding, and it is helpful to guarantee the efficiency and the finished product quality.

Description

Technical Field

[0001] The invention relates to the technical field of welding, and in particular to a sheet metal welding method, a sheet metal assembly and a vehicle. Background Art

[0002] In the field of body-in-white welding, there are often multi-layer plate overlap structures, and many structures are welded from materials of different thicknesses and costs. In the existing body-in-white welding process, for aluminum alloy plates, flow drill screw connection (FDS) or self-piercing riveting (SPR) processes are usually used, assisted by structural adhesives to achieve composite connections. This connection method has the problems of complex welding process, long single-point connection time, low efficiency, and poor quality of finished products; for galvanized plates, resistance spot welding or carbon dioxide shielded welding connection processes are usually used, which also have the problems of long single-point connection time, low efficiency, and poor quality of finished products. Summary of the invention

[0003] Embodiments of the present invention provide a sheet metal assembly, a sheet metal welding method and a vehicle to solve the problems of low efficiency and poor quality of finished products in existing sheet metal lap joints.

[0004] A sheet metal assembly includes at least two sheet metal parts and a laser welding structure; At least two of the sheet metal parts are stacked in a vertical direction, and a sheet metal gap between two adjacent sheet metal parts is smaller than a first threshold value, wherein the first threshold value is a product of a thickness of the uppermost sheet metal part and a first coefficient, and a value range of the first coefficient is [0.2, 0.4]; The laser welding structure includes a first welding structure and / or a second welding structure, wherein the first welding structure is a welding structure that does not penetrate the bottom sheet metal part in the vertical direction, and the second welding structure is a welding structure that penetrates the bottom sheet metal part in the vertical direction.

[0005] Preferably, in the first welding structure, the difference between the top melting diameter and the bottom weld core diameter of the sheet metal parts except the bottom sheet metal part is greater than or equal to 2 mm; The thickness of the unpenetrated region in the bottom sheet metal part is the product of the thickness of the bottom sheet metal part and the second coefficient, and the value range of the second coefficient is [0.25, 0.5].

[0006] Preferably, in the second welding structure, the difference between the top melting diameter and the bottom weld core diameter of any of the sheet metal parts is greater than or equal to 2 mm; The bottom weld core diameter of the bottom sheet metal part is greater than or equal to 0; The minimum distance from the edge of the bottom weld nugget area of ​​any of the sheet metal parts to the top melting area is the product of the thickness of the sheet metal part and the third coefficient, and the value range of the third coefficient is 0.6-0.7.

[0007] Preferably, in the second welding structure, the inclination angle of the melting area corresponding to any of the sheet metal parts needs to meet the following conditions: 45°≤A≤60°, and cotA*ti*f=Di; Wherein, A is the inclination angle of the melting area of ​​any of the sheet metal parts, ti is the thickness of the i-th sheet metal part, Di is the bottom weld core diameter of the i-th sheet metal part, and f is the correction factor, and the value range of the correction factor is [4, 8].

[0008] A sheet metal welding method, comprising: At least two sheet metal parts are stacked in a vertical direction so that a sheet metal gap between two adjacent sheet metal parts is less than or equal to a first threshold value, wherein the first threshold value is a product of a thickness of the uppermost sheet metal part and a first coefficient, and a value range of the first coefficient is [0.2, 0.4]; Remote laser welding is performed based on target control parameters corresponding to the target welding method to form a laser welding structure between at least two of the sheet metal parts; the laser welding structure is a first welding structure or a second welding structure, the first welding structure is a welding structure that does not penetrate the bottom sheet metal part in the vertical direction, and the second welding structure is a welding structure that penetrates the bottom sheet metal part in the vertical direction.

[0009] Preferably, the remote laser welding is performed based on the target control parameters corresponding to the target welding mode to form a laser welding structure between at least two of the sheet metal parts, including: Performing remote laser welding based on target parameters corresponding to the light spot distance, welding speed, and welding spiral trajectory corresponding to the first welding method to form a first welding structure between at least two of the sheet metal parts; Wherein, the target parameters include the starting point of the light spot, the spiral pitch and the spiral direction; The value range of the light spot distance is [t1, t1+k4*t2], t1 is the thickness of the uppermost sheet metal part, t2 is the thickness of the lowermost sheet metal part, k4 is the fourth coefficient, and the value range of the fourth coefficient is 0.3-0.4; The welding speed has a value range of [180 mm / s, 220 mm / s]; The distance between the starting point of the light spot and the center point of welding is [0.2mm, 0.5mm]; The spiral pitch is [0.2mm, 0.5mm]; The spiral direction is from inside to outside based on the welding spiral trajectory.

[0010] Preferably, the remote laser welding is performed based on the target control parameters corresponding to the target welding mode to form a laser welding structure between at least two of the sheet metal parts, including: Performing remote laser welding based on target parameters corresponding to the light spot distance, welding speed, and welding spiral trajectory corresponding to the second welding method to form a second welding structure between at least two of the sheet metal parts; Wherein, the target parameters include the starting point of the light spot, the spiral pitch and the spiral direction; The value range of the light spot distance is [k5*t1, k6*t1], t1 is the thickness of the uppermost sheet metal part, k5 is the fifth coefficient, and the value range of the fifth coefficient is [0.3, 0.5]; k6 is the sixth coefficient, and the value range of the sixth coefficient is [0.7, 0.9]; The welding speed has a value range of [180 mm / s, 220 mm / s]; The starting point of the light spot is the welding center point; The spiral pitch is [0.2mm, 0.3mm]; The spiral direction is from inside to outside based on the welding spiral trajectory.

[0011] Preferably, the remote laser welding is performed based on the target control parameters corresponding to the target welding mode to form a laser welding structure between at least two of the sheet metal parts, including: Performing first-stage welding based on a linearly increasing first welding power within a first welding time period; After the first stage welding is completed, performing the second stage welding within a second welding time period based on a constant second welding power; The first welding power is smaller than the second welding power, and the first welding duration is smaller than the second welding duration.

[0012] Preferably, the first welding time is the product of the second welding time and the seventh coefficient; if the target welding mode is the first welding mode, the value range of the seventh coefficient is [0.25, 0.35]; if the target welding mode is the second welding mode, the value range of the seventh coefficient is [0.4, 0.5]; The first welding power is determined based on the second welding power, the lower limit welding power and the first welding time. The lower limit welding power is the product of the second welding power and an eighth coefficient. The value range of the eighth coefficient is [0.6, 0.8].

[0013] A vehicle comprises the above-mentioned sheet metal assembly.

[0014] The embodiments of the present invention provide a sheet metal assembly, a sheet metal welding method and a vehicle, wherein the sheet metal gap between two adjacent sheet metal parts is less than or equal to a first threshold value, so as to meet the requirements of laser welding, so as to ensure that a qualified welding spot is formed between at least two sheet metal parts, thereby ensuring the quality of the finished product of the sheet metal assembly. A first welding structure and / or a second welding structure are provided on at least two sheet metal parts 1, wherein the first welding structure does not penetrate the bottom sheet metal part in the vertical direction, which helps to ensure the appearance quality of the sheet metal assembly, and the second welding structure penetrates the bottom sheet metal part in the vertical direction, which helps to ensure the connection strength of the sheet metal assembly, so that different welding structures can be used to connect at least two sheet metal parts according to actual conditions, so as to meet the appearance quality and / or connection strength required by the sheet metal assembly. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative labor.

[0016] Figure 1 is a cross-sectional view of a sheet metal assembly in one embodiment of the present invention; Figure 2 is another cross-sectional view of a sheet metal assembly in one embodiment of the present invention; Figure 3 is a flow chart of a sheet metal welding method in one embodiment of the present invention; Figure 4 is a schematic diagram of the laser focus position in one embodiment of the present invention; Figure 5 is a schematic diagram of a spiral trajectory of a light spot in one embodiment of the present invention; Figure 6 Schematic diagram of a gradient power curve in one embodiment of the present invention.

[0017] In the figure: 1, sheet metal part; 11, uppermost sheet metal part; 12, lowermost sheet metal part; 2, first welding structure; 3, second welding structure. DETAILED DESCRIPTION

[0018] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and 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.

[0019] In the description of the present invention, it should be understood that the terms "longitudinal", "radial", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0020] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0021] An embodiment of the present invention provides a sheet metal assembly, such as Figure 1 and Figure 2 As shown, the sheet metal assembly includes at least two sheet metal parts 1 and a laser welding structure; At least two sheet metal parts 1 are stacked in the vertical direction, and the sheet metal gap between two adjacent sheet metal parts 1 is smaller than a first threshold value, the first threshold value is the product of the thickness of the uppermost sheet metal part 11 and the first coefficient, and the value range of the first coefficient is [0.2, 0.4]; The laser welding structure includes a first welding structure 2 and / or a second welding structure 3. The first welding structure 2 is a welding structure that does not penetrate the bottom sheet metal part 12 in the vertical direction. The second welding structure 3 is a welding structure that penetrates the bottom sheet metal part 12 in the vertical direction.

[0022] As an example, the sheet metal assembly includes at least two sheet metal parts 1 stacked in a vertical direction and a laser welding structure welded on at least two sheet metal parts 1 using laser welding technology. The material and thickness of the sheet metal parts 1 are not limited. The sheet metal parts 1 here can be but are not limited to steel workpieces, galvanized sheets and other metal parts. The sheet metal gap g between two adjacent sheet metal parts 1 is less than or equal to the first threshold value to meet the laser welding requirements to ensure that a qualified weld is formed between at least two sheet metal parts 1, thereby ensuring the quality of the finished product of the sheet metal assembly. In this example, only the first welding structure 2 can be provided on at least two sheet metal parts 1, or only the second welding structure 3 can be provided, or both the first welding structure 2 and the second welding structure 3 can be provided. The first welding structure 2 does not penetrate the bottom sheet metal part 12 in the vertical direction, which helps to ensure the quality of the appearance of the sheet metal assembly. The second welding structure 3 penetrates the bottom sheet metal part 12 in the vertical direction, which helps to ensure the connection strength of the sheet metal assembly, so that different welding structures can be used to connect at least two sheet metal parts 1 according to actual conditions to meet the appearance quality and / or connection strength requirements required by the sheet metal assembly.

[0023] In one embodiment, if Figure 2 As shown, the difference between the overlap width of at least two sheet metal parts 1 and the top melting diameter of the uppermost sheet metal part 11 is less than or equal to 2 mm.

[0024] The overlap width D0 can be understood as the width of the overlapping area of ​​at least two sheet metal parts 1 in the vertical direction. Generally speaking, the value range of D0 is [5mm, 15mm], that is, 5mm≤D0≤15mm. The top melting diameter refers to the diameter of the top melting area, and the top melting area refers to the area where the top of the sheet metal part 1 melts. Generally speaking, the top melting diameter D1 of the topmost sheet metal part 11 is the same as the outermost diameter of its welding spiral track during laser welding.

[0025] As an example, assuming that the overlapping width of at least two sheet metal parts 1 is D0, and the top melting diameter of the uppermost sheet metal part 11 is D1, the difference between the overlapping width D0 of at least two sheet metal parts 1 and the top melting diameter D1 of the uppermost sheet metal part 11 is greater than or equal to 2 mm, that is, D0-D1≥2 mm. This can avoid melting through the non-overlapping area, thereby ensuring the feasibility of laser welding technology for welding at least two stacked sheet metal parts 1, and thus ensuring the welding quality.

[0026] In one embodiment, if Figure 1 As shown, in the first welding structure 2, the difference between the top melting diameter and the bottom weld core diameter of the sheet metal part 1 except the bottom sheet metal part 12 is greater than or equal to 2 mm; the thickness of the unpenetrated area in the bottom sheet metal part 12 is the product of the thickness of the bottom sheet metal part 12 and the second coefficient, and the value range of the second coefficient is [0.25, 0.5].

[0027] The bottom weld nugget diameter refers to the diameter of the bottom weld nugget region of the sheet metal component 1 , and the bottom weld nugget region specifically refers to the region where the bottom of the sheet metal component 1 melts and is welded with other sheet metal components.

[0028] As an example, assuming that the top melting diameter of the sheet metal parts 1 other than the bottom sheet metal part 12 is D1, the bottom weld core diameter of the sheet metal parts 1 other than the bottom sheet metal part 12 is D2, the thickness of the bottom sheet metal part 12 is t2, and the thickness of the incomplete weld area of ​​the bottom sheet metal part 12 is e, then in the first welding structure 2 of at least two sheet metal parts 1, the relevant parameters have the following relationship: (1) The difference between the top melting diameter D1 and the bottom weld core diameter D2 of the sheet metal parts 1 other than the bottom sheet metal part 12 is greater than or equal to 2 mm, that is, D1-D2≥2 mm. For example, when the first welding structure 2 is set between two sheet metal parts 1, the larger the bottom weld core diameter D2 of any sheet metal part 1, the greater the static tensile strength of the first welding structure 2 in the parallel direction. Since the laser energy at D1 is the largest, the energy transmitted to D2 is reduced. Therefore, D2 is smaller than D1. The closer D2 is to D1, the greater its static tensile strength in the horizontal direction.

[0029] (2) The thickness e of the un-welded area of ​​the bottom sheet metal part 12 is the product of the thickness t2 of the bottom sheet metal part 12 and the second coefficient k2. The value range of the second coefficient k2 is [0.25, 0.5], that is, e=k2*t2, 0.25*t2≤e≤0.5*t2, so that the thickness e of the un-welded area is guaranteed to be within a specific range, avoiding the thickness e of the un-welded area being too large, resulting in a small amount of melted and welded part in the bottom sheet metal part 12, causing the bottom sheet metal part 12 to be separated from other sheet metal parts 1, and avoiding the thickness e of the un-welded area being too small, which is easy to be welded through and affect the appearance quality of the sheet metal assembly.

[0030] In one embodiment, if Figure 2 As shown, in the second welding structure 3, the difference between the top melting diameter and the bottom weld core diameter of any sheet metal part 1 is greater than or equal to 2 mm; the bottom weld core diameter of the lowest sheet metal part 12 is greater than or equal to 0; the minimum distance from the edge of the bottom weld core area of ​​any sheet metal part 1 to the top melting area is the product of the thickness of the sheet metal part 1 and the third coefficient, and the value range of the third coefficient is 0.6-0.7.

[0031] As an example, assuming that the top melting diameter of any sheet metal part 1 is D1, the bottom weld core diameter of any sheet metal part 1 is D2, and the bottom weld core diameter of the bottom sheet metal part 12 is D3, then in the second welding structure 3 of at least two sheet metal parts 1, the relevant parameters have the following relationship: The difference between the top melting diameter D1 and the bottom weld core diameter D2 of any sheet metal part 1 is greater than or equal to 2 mm, that is, D1-D2≥2 mm. For example, when the second welding structure 3 is set between two sheet metal parts 1, the larger the bottom weld core diameter D2 of any sheet metal part 1, the greater the static tensile strength of the second welding structure 3 in the parallel direction. Since the laser energy at D1 is the largest, the energy transmitted to D2 is reduced. Therefore, D2 is smaller than D1. The closer D2 is to D1, the greater its static tensile strength in the horizontal direction.

[0032] The bottom weld core diameter D3 of the bottom sheet metal part 12 is greater than or equal to 0 to ensure that the bottom sheet metal part 12 can be melted through, so that it can be visually observed from the bottom of the bottom sheet metal part 12 whether the second welding structure 3 is welded through the bottom sheet metal part 12, thereby evaluating and determining its welding quality to ensure the connection strength of the second welding structure 3 along the horizontal direction.

[0033] The bottom weld nugget diameter refers to the diameter of the bottom weld nugget area of ​​the sheet metal part 1, and the bottom weld nugget area specifically refers to the area where the bottom of the sheet metal part 1 melts and is welded to other sheet metal parts. The top melting area of ​​the sheet metal part 1 refers to the area where the top of the sheet metal part 1 melts. The minimum distance from the edge of the bottom weld nugget area of ​​the sheet metal part 1 to the top melting area can be the distance between the edge of the bottom weld nugget area and its projection point along the vertical direction to the top melting area, which can be represented by tmin.

[0034] As an example, Figure 2As shown, when the second welding structure 3 is arranged on two sheet metal parts 1, assuming that the thickness of the uppermost sheet metal part 11 is t1, the minimum distance from the edge of the bottom weld core area of ​​the uppermost sheet metal part 11 to the top melting area is tmin1 and tmin2, tmin1 and tmin2 are respectively the minimum distances from the left edge and the right edge of the cross-sectional structure of the uppermost sheet metal part 11 along the vertical direction to the top melting area; the third coefficient k3 can be set to 0.6, then tmin1≥0.6*t1, tmin2≥0.6*t1, to ensure the tensile strength of the uppermost sheet metal part 11 in the vertical direction. Similarly, assuming that the thickness of the bottom sheet metal part 12 is t2, the minimum distance from the edge of the bottom weld nugget area of ​​the bottom sheet metal part 12 to the top melting area is tmin3 and tmin4, tmin3 and tmin4 are the minimum distances from the left edge and right edge of the vertical cross-sectional structure of the bottom sheet metal part 12 to the top melting area respectively; the third coefficient can be set to 0.7, then tmin3≥0.7*t2, tmin4≥0.7*t2, to ensure the tensile strength of the bottom sheet metal part 12 in the vertical direction. In this example, the greater the minimum distance from the edge of the bottom weld nugget area of ​​any sheet metal part 1 to the top melting area, the greater the tensile strength of the second welding structure 3 in the vertical direction, and the more helpful it is to ensure the quality of the finished product of the sheet metal assembly formed by at least two sheet metal parts 1 and the second welding structure 3.

[0035] In one embodiment, if Figure 2 As shown, in the second welding structure 3, the inclination angle of the melting area corresponding to any sheet metal part 1 must meet the following conditions: 45°≤A≤60°, and cotA*ti*f=D_i; Wherein, A is the inclination angle of the melting area of ​​any sheet metal part 1, ti is the thickness of the i-th sheet metal part 1, Di is the bottom weld core diameter of the i-th sheet metal part 1, and f is the correction factor, and the value range of the correction factor is [4, 8].

[0036] As an example, the inclination angle of the melting area corresponding to any sheet metal part 1 is the inclination angle of the melting area corresponding to the second welding structure 3 on the sheet metal part 1 relative to the horizontal plane, which can be represented by A. Figure 2As shown, taking the top sheet metal 11 as an example, assuming that the inclination angle of the melting area corresponding to the top sheet metal 11 is A, the thickness of the top sheet metal 11 is t1, and the bottom weld core diameter of the top sheet metal 11 is D2, it is necessary to satisfy 45°≤A≤60°, and cotA*t1*f=D2. In this example, the steeper the inclination angle A of the melting area corresponding to any sheet metal part 1, the higher the tensile strength in the 45° direction. However, when the inclination angle A of the melting area is too steep, the diameter of the bottom weld core along the horizontal direction is smaller. Through experimental comparison, it is determined that when the inclination angle of the melting area corresponding to any sheet metal part 1 satisfies the two conditions of 45°≤A≤60° and cotA*ti*f=Di, the tensile strength in the horizontal direction and the tensile strength in the 45° direction can be taken into account, thereby ensuring the quality of the finished sheet metal assembly formed by at least two sheet metal parts 1 and the second welding structure 3, so that when the sheet metal assembly is used in a vehicle, the fatigue performance and the strength of the vehicle body under complex loads in multiple directions can be guaranteed.

[0037] The embodiment of the present invention provides a sheet metal welding method, such as Figure 3 As shown, the sheet metal welding method includes the following steps: S1: stack at least two sheet metal parts 1 in a vertical direction so that the sheet metal gap between two adjacent sheet metal parts 1 is less than or equal to a first threshold value, where the first threshold value is the product of the thickness of the uppermost sheet metal part 11 and a first coefficient, and the value range of the first coefficient is [0.2, 0.4]; S2: Remote laser welding is performed based on the target control parameters corresponding to the target welding method to form a laser welding structure between at least two sheet metal parts 1; the laser welding structure is a first welding structure 2 or a second welding structure 3, the first welding structure 2 is a welding structure that does not penetrate the bottom sheet metal part 12 in the vertical direction, and the second welding structure 3 is a welding structure that penetrates the bottom sheet metal part 12 in the vertical direction.

[0038] Among them, remote laser welding is an efficient non-contact welding process. The laser beam is guided to the stacked metal workpieces at each welding position of the laser welding according to a pre-programmed sequence. The welding joint does not contact the metal workpiece. The laser beam is irradiated to the surface of the metal workpiece, and the concentrated energy released by the beam forms a welding joint between the overlapping metal workpieces. Specifically, the laser beam is guided to the top surface of the stacked metal workpieces, and the energy of the laser beam is absorbed by the metal workpieces, causing the metal workpieces to melt and form a molten weld pool in the workpieces; the molten weld pool penetrates through the metal workpiece directly irradiated by the laser beam, penetrates into one or more metal workpieces below it, breaks through the joint surface between multiple metal workpieces, and forms a metal weld after cooling, connecting multiple stacked metal workpieces.

[0039] As an example, in step S1, at least two sheet metal parts 1 can be stacked in the vertical direction, and there is no restriction on the material and thickness of the sheet metal parts 1. The sheet metal parts 1 here can be, but are not limited to, steel workpieces, galvanized sheets, and other metal parts. After the stacking of at least two sheet metal parts 1 is completed, the sheet metal gap g between any two adjacent sheet metal parts 1 needs to be measured, and the sheet metal gap g is compared with a first threshold value, which is determined based on the thickness of the top sheet metal part 11; if the sheet metal gap g between the two adjacent sheet metal parts 1 is less than or equal to the first threshold value G, it is determined that the sheet metal gap g between the two adjacent sheet metal parts 1 meets the laser welding requirements, and the subsequent step S2 can be executed; if the sheet metal gap g between the two adjacent sheet metal parts 1 is greater than the first threshold value G, it is determined that the sheet metal gap g between the two adjacent sheet metal parts 1 does not meet the laser welding requirements, and a qualified weld cannot be formed between the at least two sheet metal parts 1.

[0040] In this example, the first threshold value G is the coefficient of the thickness t1 of the top sheet metal part 11 and the first coefficient k1, that is, G=k1*t1, and the value range of the first coefficient k1 can be set to [0.2, 0.4]. Generally speaking, laser spot welding requires a smaller gap, but in reality, the smaller the sheet metal gap g between two adjacent sheet metal parts 1, the higher the precision control and tooling requirements for the sheet metal parts 1. Through experimental analysis combined with experience, the value range of the first coefficient k1 that can achieve both is determined. In this example, the first coefficient k1 can be set to 0.3, and the sheet metal gap g between two adjacent sheet metal parts 1 is between 0≤g≤0.3*t1, and a qualified weld can be formed between two adjacent sheet metal parts 1; if the sheet metal gap g between two adjacent sheet metal parts 1>0.3*t1, a qualified weld cannot be formed between two adjacent sheet metal parts 1. Generally speaking, the smaller the sheet metal gap g between two adjacent sheet metal parts 1, the higher and more reliable the strength after laser welding; the larger the sheet metal gap g between two adjacent sheet metal parts 1, the lower the strength after laser welding. When it exceeds a certain range, there will be a shortage of material when the melted material of the upper sheet metal part 1 fills the sheet metal gap.

[0041] Among them, the target welding method is the welding method required for this welding. The target welding method can be the first welding method or the second welding method. The first welding method refers to a welding method that does not require welding through the bottom layer of sheet metal 12, and the second welding method refers to a welding method that requires welding through the bottom layer of sheet metal 12.

[0042] As an example, in step S2, after determining that the sheet metal gap between at least two stacked sheet metal parts 1 meets the laser welding requirements, the target welding method and the sheet metal parameters corresponding to the at least two sheet metal parts 1 can be input into the laser welding equipment, so that the built-in controller of the laser welding equipment determines the target control parameters corresponding to the target welding method based on the target welding method and the corresponding sheet metal parameters, and controls the welding joint connected thereto to perform remote laser welding based on the target control parameters corresponding to the target welding method, so that the laser beam output by the welding joint moves along a preset welding spiral trajectory relative to the top of the at least two stacked sheet metal parts 1, and the energy provided by the laser beam melts all or part of the at least two sheet metal parts 1 to form a laser welding structure between the at least two sheet metal parts 1. When the formed laser welding structure is a first welding structure 2 that does not penetrate the bottom sheet metal part 12 in the vertical direction, it helps to ensure the appearance quality of the sheet metal assembly; when the laser welding structure is a second welding structure 3 that penetrates the bottom sheet metal part 12 in the vertical direction, it helps to ensure the connection strength of the sheet metal assembly, so that according to actual conditions, different welding structures can be used to connect at least two sheet metal parts 1 to meet the appearance quality or connection strength requirements required by the sheet metal assembly.

[0043] In one embodiment, in step S2, remote laser welding is performed based on target control parameters corresponding to the target welding method to form a laser welding structure between at least two sheet metal parts 1, including: Perform remote laser welding based on target parameters corresponding to the light spot distance, welding speed, and welding spiral trajectory corresponding to the first welding method to form a first welding structure 2 between at least two sheet metal parts 1; Among them, the target parameters include the starting point of the light spot, the spiral pitch and the spiral direction; The value range of the light spot distance is [t1, t1+k4*t2], t1 is the thickness of the uppermost sheet metal part 11, t2 is the thickness of the lowermost sheet metal part 12, k4 is the fourth coefficient, and the value range of the fourth coefficient is 0.3-0.4; The welding speed range is [180 mm / s, 220 mm / s]; The distance between the starting point of the light spot and the center point of welding is [0.2mm, 0.5mm]; The spiral pitch is [0.2mm, 0.5mm]; The spiral direction is from inside to outside based on the welding spiral trajectory.

[0044] As an example, when the target welding method is the first welding method, it is necessary to perform remote laser welding based on the target control parameters corresponding to the first welding method, that is, the welding joint of the laser welding equipment is controlled to perform remote laser welding based on the target parameters corresponding to the spot distance, welding speed, and welding spiral trajectory corresponding to the first welding method, so as to form a first welding structure 2 between at least two sheet metal parts 1. The first welding method here refers to a welding method that does not require welding through the bottom sheet metal part 12.

[0045] Among them, the target parameters corresponding to the welding spiral trajectory specifically include the starting point of the light spot, the spiral pitch and the spiral direction. The welding spiral trajectory is a trajectory used to control the movement of the output laser beam, which can be understood as controlling the direction of rotation of the welding joint of the laser welding equipment. The starting point of the light spot is the starting point of the laser spot, that is, the position of the first laser spot formed by the laser welding equipment between at least two sheet metal parts 1. The spiral pitch is the spacing between adjacent spiral line segments in the welding spiral trajectory. The spiral direction is the direction of rotation of the welding joint of the laser welding equipment controlled based on the welding spiral trajectory, which can be from the inside to the outside or from the outside to the inside.

[0046] In this example, in order to ensure that the back of the first welding structure 2 is not penetrated and that at least two sheet metal parts 1 are melted through to meet the connection strength, the target control parameters need to be set as follows: The range of the spot distance corresponding to the first welding method is [t1, t1+k4*t2], where t1 is the thickness of the top sheet metal 11, t2 is the thickness of the bottom sheet metal 12, and k4 is the fourth coefficient, and the range of the fourth coefficient is [0.2, 0.4]. The spot distance here is the distance between the top of the top sheet metal 11 and the laser spot, such as Figure 4 As shown in L; the fourth coefficient k4 is a coefficient determined by experience or experiment, and its value can be set to any specific value in [0.2, 0.4]. For example, the fourth coefficient k4 can be set to 1 / 3, and the value range of the light spot distance L corresponding to the first welding method is as follows: t1≤L≤t1+1 / 3*t2. This setting can ensure that the top sheet metal 11 is melted through, and avoid melting through the bottom sheet metal 12, so as to ensure the formation of the first welding structure 2.

[0047] The welding speed corresponding to the first welding method has a value range of [180mm / s, 220mm / s], so as to avoid the welding speed being too fast, which will reduce the welding heat input and make it impossible to fully sinter the weld, thus reducing the welding quality. It can also avoid the welding speed being too low, which will increase the weld penetration depth and width, causing cracks and holes on the weld surface, thus reducing the welding quality.

[0048] The distance between the starting point of the light spot and the center point of the welding corresponding to the first welding method is [0.2mm, 0.5mm]. Figure 5 The distance o in A. In this example, the distance o can be set to 0.3 mm, that is, in order to weld the first welding structure 2 without melting through the bottom sheet metal 12, it is necessary to set its spot starting point not to start welding from the welding center point corresponding to the welding spiral trajectory, but to determine the position 0.3 mm away from the welding center point as its spot starting point, and start welding from the spot starting point, which helps to ensure that the welding center depression is small and the appearance quality is good.

[0049] The spiral pitch corresponding to the first welding method is [0.2mm, 0.5mm]. The spiral pitch is related to the spot diameter. Figure 5 The distance s in A. In this example, the spiral pitch is set to [0.2mm, 0.5mm], and the outermost diameter of the welding spiral track can be determined by moving outward in an evenly spaced spiral. The outermost diameter of the welding spiral track is the same as the diameter of the top melting area of ​​the uppermost sheet metal part 11, which can also be represented by D1. In this example, the spiral pitch is set to [0.2mm, 0.5mm] to achieve both welding efficiency and penetration.

[0050] The spiral direction corresponding to the first welding method is from inside to outside based on the welding spiral trajectory, so that the welding joint of the laser welding equipment can be subsequently controlled to rotate from inside to outside, so that the laser spot acting on at least two sheet metal parts 1 moves from inside to outside along the welding spiral trajectory to complete the laser welding purpose.

[0051] In this example, the laser welding equipment is controlled to perform welding based on the light spot distance, welding speed, distance between the light spot starting point and the welding center point, spiral pitch and spiral direction corresponding to the first welding method to form a first welding structure 2 that does not penetrate the bottommost sheet metal 12 in the vertical direction, so that the first welding structure 2 serves as an appearance connection point between at least two sheet metal parts 1 whose appearance quality needs to be guaranteed, which helps to ensure the appearance quality of the sheet metal assembly formed thereby.

[0052] In one embodiment, in step S2, remote laser welding is performed based on target control parameters corresponding to the target welding method to form a laser welding structure between at least two sheet metal parts 1, including: Perform remote laser welding based on target parameters corresponding to the light spot distance, welding speed, and welding spiral trajectory corresponding to the second welding method to form a second welding structure 3 between at least two sheet metal parts 1; Among them, the target parameters include the starting point of the light spot, the spiral pitch and the spiral direction; The value range of the light spot distance is [k5*t1, k6*t1], t1 is the thickness of the uppermost sheet metal part 11, k5 is the fifth coefficient, and the value range of the fifth coefficient is [0.3, 0.5]; k6 is the sixth coefficient, and the value range of the sixth coefficient is [0.7, 0.9]; The welding speed range is [180 mm / s, 220 mm / s]; The starting point of the light spot is the welding center point; The spiral pitch is [0.2mm, 0.3mm]; The spiral direction is from inside to outside based on the welding spiral trajectory.

[0053] As an example, when the target welding method is the second welding method, it is necessary to perform remote laser welding based on the target control parameters corresponding to the second welding method, that is, the welding joint of the laser welding equipment is controlled to perform remote laser welding based on the target parameters corresponding to the spot distance, welding speed, and welding spiral trajectory corresponding to the second welding method, so as to form a second welding structure 3 between at least two sheet metal parts 1. The second welding method here refers to a welding method for penetrating the bottom sheet metal part 12.

[0054] In this example, in order to ensure that the back side of the second welding structure 3 is penetrated and at least two sheet metal parts 1 are melted through to meet the connection strength, the target control parameters need to be set as follows: The range of the spot distance corresponding to the second welding method is [k5*t1, k6*t1], where t1 is the thickness of the top sheet metal 11, k5 is the fifth coefficient, and the range of the fifth coefficient is [0.3, 0.5]; k6 is the sixth coefficient, and the range of the sixth coefficient is [0.7, 0.9]. The spot distance here is the distance between the top of the top sheet metal 11 and the laser spot, such as Figure 4 The fifth coefficient k5 and the sixth coefficient k6 are coefficients determined by experience or experiment. For example, when the fifth coefficient k5 is set to 0.4 and the sixth coefficient k6 is set to 0.8, the value range of the light spot distance L corresponding to the second welding method is as follows: 0.4*t1≤L1≤0.8*t1. This setting can ensure that the welding process melts through at least two sheet metal parts 1 to ensure the formation of the second welding structure 3.

[0055] (2) The welding speed corresponding to the second welding method is in the range of [180 mm / s, 220 mm / s], so as to avoid the welding speed being too fast, which will reduce the welding heat input and make it impossible to fully sinter the weld, thus reducing the welding quality. It can also avoid the welding speed being too low, which will increase the weld penetration depth and width, causing cracks and holes on the weld surface, thus reducing the welding quality.

[0056] (3) The starting point of the light spot corresponding to the second welding method is the welding center point, such as Figure 5B. In this example, it is necessary to control the laser welding equipment to start welding from the welding center point corresponding to the welding spiral track to ensure that it can provide sufficient energy to melt through at least two sheet metal parts 1, thereby ensuring the connection strength of the second welding structure 3 formed between at least two sheet metal parts 1.

[0057] (4) The spiral pitch corresponding to the second welding method is [0.2mm, 0.3mm], so that the spiral pitch is slightly smaller than the spot diameter. During welding, the upper and lower welds overlap partially. Through multiple local repetitions of the laser line and the full stirring and oscillation of the laser spot in the molten pool, the second welded structure 3 formed is fully melted and the internal structure is evenly distributed. In this example, the spiral pitch is set to [0.2mm, 0.3mm], and the outermost diameter of the welding spiral trajectory can be determined by moving outward in an evenly spaced spiral.

[0058] (5) The spiral direction corresponding to the second welding method is from inside to outside based on the welding spiral trajectory, so that the welding joint of the laser welding equipment can be subsequently controlled to rotate from inside to outside, so that the laser spot acting on at least two sheet metal parts 1 moves from inside to outside along the welding spiral trajectory to complete the laser welding purpose.

[0059] In this example, the laser welding equipment is controlled to perform welding based on the light spot distance, welding speed, distance between the light spot starting point and the welding center point, spiral pitch and spiral direction corresponding to the second welding method to form a second welding structure 3 that penetrates the bottom sheet metal 12 in the vertical direction, so that the second welding structure 3 fully penetrates at least two sheet metal parts 1 to ensure the connection strength of the sheet metal assembly formed thereby.

[0060] In one embodiment, step S2, i.e., performing remote laser welding based on target control parameters corresponding to the target welding method to form a laser welding structure between at least two sheet metal parts 1, includes: Performing first-stage welding based on a linearly increasing first welding power within a first welding time period; After the first stage welding is completed, performing the second stage welding within a second welding time period based on a constant second welding power; The first welding power is smaller than the second welding power, and the first welding duration is smaller than the second welding duration.

[0061] The first welding power is the welding power of the first stage, and the second welding power is the welding power of the second stage. The welding power here is determined by the total penetration thickness and welding speed of two adjacent sheet metal parts 1. The first welding time is the welding time of the first stage, and the second welding time is the welding time of the second stage.

[0062] As an example, as the laser beam moves from the inside to the outside along the welding spiral trajectory, the laser energy includes the radiation direction and the conduction direction, so that during the welding process, the energy is most concentrated at the most central position of the welding spiral trajectory, and collapse or back bulge is most likely to occur. During the welding process of at least two sheet metal parts 1, it can be divided into two welding stages. The specific welding process is as follows: the first stage welding is performed based on a linearly increasing first welding power within a first welding duration, that is, welding is performed based on a continuously increasing first welding power within a shorter first welding duration; after the first stage welding is completed, the second stage welding is performed based on a constant second welding power within a second welding duration, that is, welding is performed based on a constant larger second welding power within a longer second welding duration. This welding process helps to avoid collapse or back bulge between two adjacent sheet metal parts, thereby ensuring welding quality.

[0063] In one embodiment, the first welding time is the product of the second welding time and the seventh coefficient; if the target welding mode is the first welding mode, the value range of the seventh coefficient is [0.25, 0.35]; if the target welding mode is the second welding mode, the value range of the seventh coefficient is [0.4, 0.5]; The first welding power is determined based on the second welding power, the lower limit welding power and the first welding time. The lower limit welding power is the product of the second welding power and the eighth coefficient. The value range of the eighth coefficient is [0.6, 0.8].

[0064] As an example, when the target welding mode is the first welding mode, it is necessary to first determine the larger second welding power P2 and the corresponding second welding time T2 according to the total penetration thickness and welding speed of the two adjacent sheet metal parts 1. For example, the pre-set mapping table can be queried based on the total penetration thickness and welding speed to determine the corresponding second welding power P2 and second welding time T2. Then, based on the product of the second welding time T2 and the seventh coefficient k7, the corresponding first welding time T1 is determined. The value range of the seventh coefficient k7 here is [0.25, 0.35]. For example, it can be set to 0.3, that is, T1=k7*T2=0.3*T2. Based on the product of the second welding power P2 and the eighth coefficient k8, the corresponding lower limit welding power Pmin is determined. The value range of the eighth coefficient here is [0.6, 0.8]. For example, it can be set to 0.7, that is, Pmin=k8*P2=0.7*P2. Finally, based on the second welding power P2, the lower limit welding power Pmin, and the first welding time T1, a power rise curve is determined, and the first welding power P1 corresponding to the current welding time is determined according to the current welding time and the power rise curve. Figure 6As shown, in the specific welding process, the welding joint is first controlled to perform the first stage welding based on the continuously increasing first welding power P1 within a shorter first welding time T1; then, the second stage welding is performed based on the constant second welding power P2 within a longer second welding time T2 to form a first welding structure 2, thereby avoiding collapse or back bulge between two adjacent sheet metal parts, thereby ensuring the welding quality.

[0065] As an example, when the target welding mode is the second welding mode, it is necessary to first determine the larger second welding power P2 and the corresponding second welding time T2 according to the total penetration thickness and welding speed of the two adjacent sheet metal parts 1. For example, the pre-set mapping table can be queried based on the total penetration thickness and welding speed to determine the corresponding second welding power P2 and second welding time T2. Then, based on the product of the second welding time T2 and the seventh coefficient k7, the corresponding first welding time T1 is determined. The value range of the seventh coefficient k7 here is [0.4, 0.5]. For example, it can be set to 0.45, that is, T1==k7*T2=0.45*T2. Based on the product of the second welding power P2 and the eighth coefficient k8, the corresponding lower limit welding power Pmin is determined. The value range of the eighth coefficient here is [0.6, 0.8]. For example, it can be set to 0.7, that is, Pmin==k8*P2=0.7*P2. Finally, based on the second welding power P2, the lower limit welding power Pmin, and the first welding time T1, a power rise curve is determined, and the first welding power P1 corresponding to the current welding time is determined according to the current welding time and the power rise curve. Figure 6 As shown, in a specific welding process, after determining the first welding power P1, the first welding time T1, the second welding power P2 and the second welding time T2, the welding joint can be controlled to perform the first stage welding within the shorter first welding time T1 based on the continuously increasing first welding power P1; then, within the longer second welding time T2, the second stage welding is performed based on the constant second welding power P2 to form a second welding structure 3, thereby avoiding collapse or back bulge between two adjacent sheet metal parts, thereby ensuring the welding quality.

[0066] An embodiment of the present invention provides a vehicle, comprising the sheet metal assembly in the above embodiment.

[0067] The vehicle provided in this example includes the sheet metal assembly in the above embodiment, in which the sheet metal gap g between two adjacent sheet metal parts 1 is less than or equal to the first threshold value to meet the laser welding requirements, to ensure that a qualified weld is formed between at least two sheet metal parts 1, and thus to ensure the quality of the finished product of the sheet metal assembly. In this example, only the first welding structure 2 can be provided on at least two sheet metal parts 1, or only the second welding structure 3 can be provided, or both the first welding structure 2 and the second welding structure 3 can be provided, the first welding structure 2 does not penetrate the bottom sheet metal part 12 in the vertical direction, which helps to ensure the appearance quality of the sheet metal assembly, and the second welding structure 3 penetrates the bottom sheet metal part 12 in the vertical direction, which helps to ensure the connection strength of the sheet metal assembly, so that different welding structures can be used to connect at least two sheet metal parts 1 according to actual conditions to meet the appearance quality and / or connection strength requirements required by the sheet metal assembly.

[0068] The embodiments described above are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included in the protection scope of the present invention.

Claims

1. A sheet metal assembly, characterized in that: including at least two sheet metal parts and a laser welded structure; At least two of the sheet metal parts are stacked in a vertical direction, and a sheet metal gap between two adjacent sheet metal parts is smaller than a first threshold value, wherein the first threshold value is a product of a thickness of the uppermost sheet metal part and a first coefficient, and a value range of the first coefficient is [0.2, 0.4]; The laser welding structure includes a first welding structure and / or a second welding structure, wherein the first welding structure is a welding structure that does not penetrate the bottom sheet metal part in the vertical direction, and the second welding structure is a welding structure that penetrates the bottom sheet metal part in the vertical direction.

2. The sheet metal assembly according to claim 1, characterized in that: In the first welding structure, the difference between the top melting diameter and the bottom weld core diameter of the sheet metal parts other than the bottom sheet metal part is greater than or equal to 2 mm; The thickness of the unpenetrated region in the bottom sheet metal part is the product of the thickness of the bottom sheet metal part and the second coefficient, and the value range of the second coefficient is [0.25, 0.5].

3. The sheet metal assembly according to claim 1, characterized in that: In the second welding structure, the difference between the top melting diameter and the bottom weld core diameter of any of the sheet metal parts is greater than or equal to 2 mm; The bottom weld core diameter of the bottom sheet metal part is greater than or equal to 0; The minimum distance from the edge of the bottom weld nugget area of ​​any of the sheet metal parts to the top melting area is the product of the thickness of the sheet metal part and the third coefficient, and the value range of the third coefficient is 0.6-0.

7.

4. The sheet metal assembly according to claim 1, characterized in that: In the second welding structure, the inclination angle of the melting area corresponding to any of the sheet metal parts must meet the following conditions: 45°≤A≤60°, and cotA*ti*f=Di; Wherein, A is the inclination angle of the melting area of ​​any of the sheet metal parts, ti is the thickness of the i-th sheet metal part, Di is the bottom weld core diameter of the i-th sheet metal part, and f is the correction factor, and the value range of the correction factor is [4, 8].

5. A sheet metal welding method, characterized in that: include: At least two sheet metal parts are stacked in a vertical direction so that a sheet metal gap between two adjacent sheet metal parts is less than or equal to a first threshold value, wherein the first threshold value is a product of a thickness of the uppermost sheet metal part and a first coefficient, and a value range of the first coefficient is [0.2, 0.4]; Remote laser welding is performed based on target control parameters corresponding to the target welding method to form a laser welding structure between at least two of the sheet metal parts; the laser welding structure is a first welding structure or a second welding structure, the first welding structure is a welding structure that does not penetrate the bottom sheet metal part in the vertical direction, and the second welding structure is a welding structure that penetrates the bottom sheet metal part in the vertical direction.

6. The sheet metal welding method according to claim 5, characterized in that: The remote laser welding is performed based on the target control parameters corresponding to the target welding mode to form a laser welding structure between at least two of the sheet metal parts, including: Performing remote laser welding based on target parameters corresponding to the light spot distance, welding speed, and welding spiral trajectory corresponding to the first welding method to form a first welding structure between at least two of the sheet metal parts; Wherein, the target parameters include the starting point of the light spot, the spiral pitch and the spiral direction; The value range of the light spot distance is [t1, t1+k4*t2], t1 is the thickness of the uppermost sheet metal part, t2 is the thickness of the lowermost sheet metal part, k4 is the fourth coefficient, and the value range of the fourth coefficient is 0.3-0.4; The welding speed has a value range of [180 mm / s, 220 mm / s]; The distance between the starting point of the light spot and the center point of welding is [0.2mm, 0.5mm]; The spiral pitch is [0.2mm, 0.5mm]; The spiral direction is from inside to outside based on the welding spiral trajectory.

7. The sheet metal welding method according to claim 5, characterized in that: The remote laser welding is performed based on the target control parameters corresponding to the target welding mode to form a laser welding structure between at least two of the sheet metal parts, including: Performing remote laser welding based on target parameters corresponding to the light spot distance, welding speed, and welding spiral trajectory corresponding to the second welding method to form a second welding structure between at least two of the sheet metal parts; Wherein, the target parameters include the starting point of the light spot, the spiral pitch and the spiral direction; The value range of the light spot distance is [k5*t1, k6*t1], t1 is the thickness of the uppermost sheet metal part, k5 is the fifth coefficient, and the value range of the fifth coefficient is [0.3, 0.5]; k6 is the sixth coefficient, and the value range of the sixth coefficient is [0.7, 0.9]; The welding speed has a value range of [180 mm / s, 220 mm / s]; The starting point of the light spot is the welding center point; The spiral pitch is [0.2mm, 0.3mm]; The spiral direction is from inside to outside based on the welding spiral trajectory.

8. The sheet metal welding method according to claim 5, characterized in that: The remote laser welding is performed based on the target control parameters corresponding to the target welding mode to form a laser welding structure between at least two of the sheet metal parts, including: Performing first-stage welding based on a linearly increasing first welding power within a first welding time period; After the first stage welding is completed, performing the second stage welding within a second welding time period based on a constant second welding power; The first welding power is smaller than the second welding power, and the first welding duration is smaller than the second welding duration.

9. The sheet metal welding method according to claim 8, characterized in that: The first welding time is the product of the second welding time and the seventh coefficient; if the target welding mode is the first welding mode, the value range of the seventh coefficient is [0.25, 0.35]; if the target welding mode is the second welding mode, the value range of the seventh coefficient is [0.4, 0.5]; The first welding power is determined based on the second welding power, the lower limit welding power and the first welding time. The lower limit welding power is the product of the second welding power and an eighth coefficient. The value range of the eighth coefficient is [0.6, 0.8].

10. A vehicle, characterized in that: Comprising the sheet metal assembly described in any one of claims 1-4.

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