Welding method of flexible connection copper bar

Abstract

A welding method for a flexible connection copper bar comprises the following steps that S1, a silver soldering lug is placed at a to-be-welded point position on the flexible copper bar, and the silver soldering lug and the to-be-welded point position are tightly attached; and S2, after fitting is completed, laser equipment is started, and spot welding is carried out on the fitting position of the silver soldering lug and the soft copper bar along a preset spiral line-shaped path. According to the utility model, a spiral line-shaped path is adopted for welding, so that the defect that a silver soldering lug is easy to point through in point-shaped welding is avoided, and meanwhile, the welding contact area is increased through full coverage of the spiral path, so that the welding firmness is not lower than 10N, and the use requirement of a new energy automobile is met; when two or four independent spiral paths are adopted, through the symmetrical or annular distribution design, the distribution uniformity of welding spots is further optimized, local energy overload is avoided, and meanwhile the overall welding stability is improved.

Description

Technical Field

[0001] This invention relates to the field of flexible copper busbar welding technology, and more specifically to a welding method for flexible copper busbars. Background Technology

[0002] As a core conductive component in the battery pack and electronic control system of new energy vehicles, the flexible copper busbar directly affects the circuit conductivity stability and structural reliability through its welding quality with silver solder sheets. In existing technologies, laser spot welding often employs spot or concentric welding paths (such as...). Figure 4 and Figure 5 As shown, there are obvious defects: spot welding is prone to local energy concentration of silver solder sheets and can be punctured, causing adhesion failure; concentric welding has limited contact area and insufficient welding strength, which cannot meet the requirement of new energy vehicles for a tensile force of not less than 10N for connecting parts. Summary of the Invention

[0003] The purpose of this invention is to solve the problems in the prior art where spot welding easily leads to local energy concentration of silver solder sheets, resulting in point penetration and adhesion failure; and concentric welding has limited contact area and insufficient welding strength. Therefore, this invention proposes a welding method for flexible copper busbars.

[0004] The objective of this invention can be achieved through the following technical solutions: A method for welding flexible copper busbars includes the following steps: S1. Place the silver solder sheet on the soft copper busbar at the point to be soldered, so that the two are tightly attached; S2. After bonding is completed, the laser equipment is started and spot welded to the bonding area between the silver solder sheet and the soft copper busbar along the preset spiral path.

[0005] As a further aspect of the present invention: In step S2, the spiral path is coaxially spiraled with the geometric center of the silver solder sheet as the spiral center, and the spiral direction is clockwise or counterclockwise.

[0006] As a further aspect of the present invention: the number of spiral turns is 1 to n, the pitch is 0.1 to 2 mm and is evenly distributed along the spiral path, the outer diameter of the spiral is adapted to the maximum lateral dimension of the silver solder sheet, the inner diameter of the spiral is not less than 1 / 3 of the maximum lateral dimension of the silver solder sheet, and the spiral path covers the effective contact area between the silver solder sheet and the soft copper busbar throughout the entire process.

[0007] As a further aspect of the present invention: the laser performs spot welding along the spiral path at preset intervals, with the weld spot spacing being 0.2 to 1 mm.

[0008] As a further aspect of the present invention: In step S2, spot welding is performed on the bonding area between the silver solder sheet and the soft copper busbar along at least two preset independent spiral paths, and the at least two independent spiral paths are symmetrically or circularly distributed with the geometric center of the silver solder sheet as the reference.

[0009] As a further aspect of the present invention: each spiral path is coaxially spiraled with its own preset path center as the spiral center, and the spiral direction is clockwise or counterclockwise.

[0010] As a further aspect of the present invention: the laser performs spot welding along each of the spiral paths at preset intervals, the spacing between the weld points on a single spiral path is 0.2 to 1 mm, and the weld points of all spiral paths do not overlap and uniformly cover the bonding surface of the silver solder sheet and the soft copper busbar.

[0011] As a further aspect of the present invention: when there are 4 spiral paths, the centers of the four spiral paths are distributed in a square or rhombus shape, and the center of the square or rhombus coincides with the geometric center of the silver solder sheet.

[0012] As a further aspect of the present invention: In step S1, the soft copper busbar needs to undergo surface cleaning treatment before placement to remove surface oil, oxide layer and impurities. The cleaning method is polishing or wiping.

[0013] As a further aspect of the present invention: the welding power of the laser equipment is 50-300W, the welding speed is 10-50mm / s, the laser outputs energy uniformly along each spiral path, and the energy input of a single weld point is 0.1-0.5J, so as to avoid the damage of the silver solder sheet caused by concentrated energy at a single point.

[0014] The beneficial effects of this invention are as follows: the spiral path welding avoids the defect of easy penetration of silver solder sheets by point welding, and the full coverage of the spiral path increases the welding contact area, so that the welding strength is not less than 10N, which meets the requirements of new energy vehicles. When using two or four independent spiral paths, the uniformity of weld point distribution can be further optimized through symmetrical or ring-shaped distribution design, avoiding local energy overload and improving the overall stability of the weld. Attached Figure Description

[0015] The invention will now be further described with reference to the accompanying drawings.

[0016] Figure 1 This is a flowchart illustrating the present invention; Figure 2 This is a schematic diagram of the structure of the present invention; Figure 3 This is a schematic diagram of the spiral path welding of the present invention; Figure 4This is a point welding path in existing technology; Figure 5 It is a concentric welding path in the existing technology.

[0017] In the diagram: 1. Soft copper busbar; 2. Silver solder sheet. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] like Figure 1-3 As shown, Example 1: Single spiral linear path welding This embodiment uses a single spiral path to complete the welding.

[0020] Clean the surface of the soft copper busbar 1 to be soldered: gently polish the area to be soldered with 1200-grit sandpaper to remove the surface oxide layer, then wipe it with a lint-free cloth moistened with anhydrous ethanol to remove oil stains and polishing residue, and let it dry before use to avoid contaminants affecting the soldering adhesion and conductivity.

[0021] Fitting operation: After cleaning, the soft copper busbar 1 is fixed on the positioning fixture of the welding station, and the positioning accuracy is controlled within ±0.05mm. The silver solder sheet 2 is precisely placed at the welding point of the soft copper busbar 1 by manual or automated pressing mechanism. The pressing pressure of the pressing mechanism is set to 0.3MPa to ensure that the silver solder sheet 2 is tightly attached to the surface of the soft copper busbar 1, with no gaps or offsets in the contact surface.

[0022] Spiral laser spot welding: The equipment used is a fiber laser welding device that supports custom path editing and has stable energy output.

[0023] The equipment control system presets the following spiral path parameters: the geometric center of the silver solder sheet 2 is the spiral center, and the spiral direction is clockwise; the number of spiral turns is 2, the pitch is 1mm and it is evenly distributed along the spiral path; the outer diameter of the spiral is adapted to the maximum lateral dimension of the silver solder sheet 2, which is 8mm, and is set to 8mm; the inner diameter of the spiral is 3mm (not less than 1 / 3 of the maximum lateral dimension of the silver solder sheet 2, i.e., 8mm×1 / 3≈2.67mm), ensuring that the spiral path fully covers the effective contact area between the silver solder sheet 2 and the soft copper busbar 1.

[0024] Set the laser welding parameters: welding power 150W, welding speed 30mm / s, energy input of a single weld point is 0.3J; the laser performs spot welding along a preset spiral path at preset intervals of 0.5mm, the weld points are evenly distributed, and energy concentration at a single point is avoided.

[0025] Once the laser equipment is activated, the laser beam sequentially completes the spot welding operation along a preset spiral path. During the welding process, the status of the weld points is observed in real time through the equipment's built-in visual monitoring system to ensure that there are no incomplete welds or missed welds.

[0026] Example 2: Welding with dual independent spiral paths This embodiment uses two independent spiral paths to complete the welding.

[0027] Fitting operation: The silver solder sheet 2 is precisely placed on the soldering point of the soft copper busbar 1, and a pressure of 0.25MPa is applied by the pressing mechanism to ensure that the two are tightly attached.

[0028] Double-helix laser spot welding: The laser device still uses the one in Example 1, which presets two independent spiral paths through the control system: they are symmetrically distributed with the geometric center of the silver solder sheet 2 as the reference, the line connecting the centers of the two spiral paths is parallel to the length direction of the silver solder sheet 2, and the center distance is 1 / 3 of the maximum lateral dimension (10mm) of the silver solder sheet 2, that is, about 3.3mm.

[0029] The parameters for each helical path are set as follows: the paths are coaxially spiraled with their respective center as the spiral center. One path is clockwise and the other is counterclockwise (this can be adjusted according to actual needs or kept in the same direction). The number of spiral turns is 2, the pitch is 0.8mm, the outer diameter of a single spiral is 2 / 3 of the lateral dimension of the corresponding area of ​​the silver solder sheet 2, which is about 6.7mm, and the inner diameter of the spiral is 2mm. The laser performs spot welding along each spiral path at intervals of 0.4mm, and the energy input of a single weld spot is 0.25J.

[0030] Laser welding parameters: welding power 120W, welding speed 25mm / s, the laser beam sequentially completes spot welding along two independent spiral paths, the weld points of all spiral paths do not overlap, and the entire surface of the silver solder sheet 2 and soft copper busbar 1 is uniformly covered.

[0031] Example 3: Welding of four independent spiral paths This embodiment uses four independent spiral paths to complete the welding.

[0032] Fitting operation: Place the silver solder sheet 2 on the soldering point of the soft copper busbar 1, and apply a pressure of 0.4 MPa using the pressing mechanism to ensure a seamless fit.

[0033] Four-helix laser spot welding: The laser equipment control system has four preset independent spiral paths: they are evenly distributed in a ring around the geometric center of the silver solder sheet 2, and the centers of the four spiral paths are distributed in a square. The center of the square coincides with the geometric center of the silver solder sheet 2. The side length of the square is 1 / 3 of the maximum lateral dimension (12mm) of the silver solder sheet 2, which is 4mm. The center distance between two adjacent spiral paths is 4mm.

[0034] Parameters for each spiral path: The spirals are coaxially distributed with the center of each path as the spiral center, and the spiral direction is clockwise; the number of spiral turns is 1.5 turns, the pitch is 0.6mm, the outer diameter of a single spiral is 1 / 2 of the lateral dimension of the corresponding area of ​​the silver solder sheet 2, i.e., 6mm, and the inner diameter of the spiral is 2mm; the laser performs spot welding along each spiral path at intervals of 0.3mm, and the energy input of a single weld spot is 0.2J.

[0035] Laser welding parameters: welding power 100W, welding speed 20mm / s, the laser beam completes spot welding of 4 spiral paths in a preset order, and the shortest distance between different spiral paths is 0.5mm to avoid weld interference.

[0036] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention. The scope of protection claimed by the appended claims and their equivalents is defined.

Claims

1. A method of welding a flexible copper busbar, characterized by, The method comprises the following steps: S1, placing the silver soldering sheet on the soft copper bar at the welding point, so that the two are closely attached; S2, after the attachment is completed, the laser equipment is started, and the attachment of the silver soldering sheet and the soft copper bar is spot welded along the preset spiral line path.

2. The welding method according to claim 1, characterized in that, In the S2 step, the spiral line path takes the geometric center of the silver soldering sheet as the spiral center and is coaxially distributed in a spiral shape, and the spiral direction is clockwise or counterclockwise.

3. The welding method according to claim 2, characterized in that The number of spiral turns is 1-n turns, the pitch is 0.1-2mm and is uniformly distributed along the spiral path, the spiral outer diameter is matched with the maximum transverse size of the silver soldering sheet, the spiral inner diameter is not less than 1 / 3 of the maximum transverse size of the silver soldering sheet, and the spiral path covers the effective attachment area of the silver soldering sheet and the soft copper bar.

4. The welding method according to claim 2, characterized in that, The laser is spot welded along the spiral line path at a preset interval, and the welding point spacing is 0.2-1mm.

5. The welding method of claim 1, wherein In the S2 step, the attachment of the silver soldering sheet and the soft copper bar is spot welded along at least two independent spiral line paths, and the at least two independent spiral line paths are symmetrically or annularly distributed with the geometric center of the silver soldering sheet as the reference.

6. The welding method according to claim 5, characterized in that Each spiral line path takes the preset path center as the spiral center and is coaxially distributed in a spiral shape, and the spiral direction is clockwise or counterclockwise.

7. The welding method according to claim 5, characterized in that The laser is spot welded along each spiral line path at a preset interval, and the welding point spacing on a single spiral path is 0.2-1mm, and the welding points of all spiral paths do not overlap and uniformly cover the attachment surface of the silver soldering sheet and the soft copper bar.

8. The welding method of claim 5, wherein When the number of spiral line paths is four, the centers of the four spiral paths are distributed in a square or a regular rhombus, and the center of the square or the regular rhombus coincides with the geometric center of the silver soldering sheet.

9. The welding method of claim 1, wherein In the S1 step, the soft copper bar needs to be surface cleaned before being placed, and the surface oil, oxide layer and impurities are removed, and the cleaning method is polishing or wiping.

10. The welding method of claim 1, wherein The welding power of the laser equipment is 50-300W, the welding speed is 10-50mm / s, the laser uniformly outputs energy along each spiral path, the energy input of a single welding point is 0.1-0.5J, and the single-point energy concentration is avoided to cause damage to the silver soldering sheet.

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