A friction stir welding manufacturing method of copper-aluminum composite bus bar

Abstract

This invention discloses a method for manufacturing copper-aluminum composite busbars using friction stir welding. A specialized stirring head for copper-aluminum composite friction stir welding is designed, increasing the diameter of the stirring head shoulder and the stirring needle tip. The stirring needle is changed from a traditional conical shape to a cylindrical shape, increasing the heat generation at the copper-aluminum interface of the composite busbar. The right-hand thread at 1 / 4 of the stirring needle's length is designed as a concave corrugated morphology along the thickness direction, with a corrugation width approximately 1 / 4 of the stirring needle's length. This increases the turbulent stirring effect during copper-aluminum interface welding and the contact area between dissimilar metals, improving the weld strength after copper-aluminum friction stir welding. The complex structure copper-aluminum composite busbar friction stir welding process solves the problem of conventional welding methods being unable to weld copper and aluminum over large areas and in three-dimensional structures. By locally welding a layer of copper alloy onto an aluminum alloy substrate, the manufacturing of complex copper-aluminum busbars with complex structures is achieved.

Description

Technical Field

[0001] This invention relates to the field of product manufacturing technology, and in particular to a method for manufacturing a copper-aluminum composite busbar by friction stir welding. Background Technology

[0002] Busbars, as mainstream high-current electrical connectors, are widely used in the aerospace, electronics, and rail transportation industries. Conventional electrical connector busbars are mainly made of copper alloy or aluminum alloy. Copper busbars are primarily used in applications with high current carrying capacity, offering advantages such as excellent conductivity, high mechanical strength, and good corrosion resistance, but also disadvantages such as heavy weight and high cost. Aluminum busbars are mainly used in applications with relatively low current carrying capacity, offering advantages such as low cost and lightweight design, but also disadvantages such as weak conductivity and low mechanical strength.

[0003] With the increasing demands for integration, high power, lightweight, and low cost in electronic equipment, conventional copper or aluminum busbars can no longer meet the requirements. Copper-aluminum composite busbars combine the advantages of both copper and aluminum, satisfying both the requirements for higher current carrying capacity and achieving lightweight and low cost. However, current traditional copper-aluminum dissimilar metal welding methods, such as friction stir welding and fusion welding, can only weld butt joints and cannot achieve large-area and three-dimensional welding of copper and aluminum. This results in a lack of reliable manufacturing solutions for large-size busbars with complex structures, which still rely on pure copper alloy or aluminum alloy busbars. Therefore, the need to break through the manufacturing process of large-size copper-aluminum composite busbars with complex structures is urgent. Summary of the Invention

[0004] To address the challenge of reliably welding large-area and three-dimensional copper-aluminum composite busbars during manufacturing, a stirring head specifically designed for copper-aluminum composite friction stir welding was developed. This allows for the addition of a highly reliable copper alloy layer to the aluminum alloy busbar substrate, enabling the high-reliability and low-cost manufacturing of complex, large-size copper-aluminum composite busbars.

[0005] This invention is achieved through the following scheme: A method for manufacturing a copper-aluminum composite busbar by friction stir welding includes the following steps: Step 1: Aluminum alloy busbar processing: Processing aluminum alloy busbars with stepped structures; The second step is the copper-aluminum friction stir welding of the first surface; a special stirring head is used to weld the copper alloy piece by piece according to the parts that need to be welded, and the aluminum alloy is locally forced to cool. The special stirring head is based on the traditional stirring head with the following changes: (1) The stirring pin is divided into three sections in the length H direction. The head and root 1 / 4 H area are conventional right-handed single spiral morphology, and the middle 1 / 2 H area is concave wave morphology in the up-down direction. This increases the turbulent stirring effect and the contact area between dissimilar metals during copper-aluminum interface welding, and improves the weld strength after copper-aluminum friction lap welding; (2) The stirring pin has a smaller taper than the conventional stirring pin, and the overall diameter W is more than 30% larger than the conventional stirring pin. This ensures uniform heat generation at the interface during welding and improves the efficiency of friction lap welding. The third step involves copper-aluminum friction stir welding on the second side, using the same welding method as the second step. Step 4: Fine machining of copper-aluminum composite busbar; the copper alloy on the welded surface is machined to retain a copper alloy layer of a set thickness.

[0006] Step 5: Apply powder coating to the surface of the copper-aluminum composite busbar for protection.

[0007] Preferably, in the first step, the aluminum alloy material is a 5-series aluminum alloy, and the busbar thickness is 10-12mm.

[0008] Preferably, in the second step, the copper alloy material is T2 copper with a thickness of 2.5-3mm.

[0009] Preferably, in the second step, when welding one strip at a time, the width of each weld is W, the overlap area is 1 / 4W, the welding speed is 100-200mm / s, the rotation speed is 1000-2000r / min, and X-ray inspection is performed after welding to prevent internal defects.

[0010] Preferably, in the second step, the forced cooling of the aluminum alloy in a localized area specifically involves using tooling and an external cooling source to locally cool only the aluminum alloy below the weld, preventing the aluminum alloy from melting due to excessively high temperatures during copper-aluminum welding, which could lead to welding defects.

[0011] Preferably, in the fourth step, the set thickness is 1-1.5mm.

[0012] Compared with the prior art, the significant advantages of this invention are: I. Through the design of lightweight busbar connectors, the design of friction stir welding stirring heads, and the breakthrough in friction stir welding, we have achieved the manufacturing of large-size lightweight copper-aluminum composite busbars. By directly welding a layer of copper alloy onto the aluminum alloy busbar substrate, we can meet the large current carrying requirements of conventional copper busbars while also achieving the requirements of lightweight and low cost for aluminum busbars.

[0013] 2. A stirring head specifically designed for copper-aluminum composite friction stir welding was developed. The diameter of the stirring head shoulder and stirring needle tip was increased, and the stirring needle was changed from the traditional conical shape to a cylindrical shape to increase the heat generation at the copper-aluminum interface of the copper-aluminum composite manifold. The right-hand thread at 1 / 4 of the stirring needle length was designed as an inwardly concave corrugated morphology along the thickness direction, with the corrugated morphology width being approximately 1 / 4 of the stirring needle length. This increases the turbulent stirring effect and the contact area between dissimilar metals during copper-aluminum interface welding, thereby improving the weld strength after copper-aluminum friction stir welding.

[0014] Third, the complex structure copper-aluminum composite busbar adopts a friction stir welding process, which solves the problem that conventional welding methods cannot weld copper and aluminum in large areas and three-dimensional structures. A layer of copper alloy is locally welded on the aluminum alloy substrate, realizing the manufacturing of complex structure copper-aluminum busbars. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the copper-aluminum composite friction stir welding head of the present invention.

[0016] Figure 2 This is a schematic diagram of the complex three-dimensional aluminum alloy busbar of the present invention.

[0017] Figure 3 This is a schematic diagram of the first copper-aluminum friction stir welding of the present invention.

[0018] Figure 4 This is a schematic diagram of the second copper-aluminum friction stir welding of the present invention.

[0019] Figure 5 This is a schematic diagram of the finished lightweight high-current copper-aluminum busbar of the present invention.

[0020] Figure 6 This is a physical image of the finished product of the lightweight high-current copper-aluminum busbar of this invention. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings.

[0022] This example demonstrates a welding and manufacturing method for a high-power, lightweight copper-aluminum busbar in electronic equipment, comprising the following steps: Step 1: Large-size aluminum alloy busbar processing: The aluminum alloy material is 5-series aluminum alloy, and the busbar thickness is 10-12mm; Step 2, First-side copper-aluminum friction stir welding: The copper alloy material is T2 copper, 2.5-3mm thick, using a special stirring head for copper-aluminum friction stir welding (attached). Figure 1Welding is performed section by section according to the required areas. Each weld width is W, with an overlap area of ​​1 / 4W. The welding speed is 100-200 mm / s, and the rotation speed is 1000-2000 r / min. X-ray inspection is performed after welding to prevent internal defects. The special stirring head is based on the traditional stirring head with the following changes: (1) The stirring pin is divided into three sections in the length H direction. The head and root 1 / 4 H area are conventional right-handed single spiral morphology, and the middle 1 / 2 H area is concave wave morphology in the up-down direction. This increases the turbulent stirring effect and the contact area between dissimilar metals during copper-aluminum interface welding, and improves the weld strength after copper-aluminum friction lap welding; (2) The stirring pin has a smaller taper than the conventional stirring pin, and the overall diameter W is more than 30% larger than the conventional stirring pin. This ensures uniform heat generation at the interface during welding and improves the efficiency of friction lap welding. Step 3, copper-aluminum friction stir welding on the second side: the welding steps and parameters are the same as in step 2; Step 4: Processing according to final dimensions: Machining the welded surface with copper alloy, retaining a 1-1.5mm copper alloy layer to form a lightweight, high-current copper-aluminum busbar. Step 5: Apply powder coating for surface protection.

[0023] The specific embodiments described herein are merely illustrative of the spirit of the invention. Those skilled in the art to which this invention pertains may make various modifications, additions, or similar substitutions to the described specific embodiments without departing from the spirit of the invention or exceeding the scope defined by the appended claims.

Claims

1. A method for manufacturing a copper-aluminum composite busbar by friction stir welding, characterized in that, Includes the following steps: Step 1: Aluminum alloy busbar processing: Processing aluminum alloy busbars with stepped structures; The second step is the copper-aluminum friction stir welding of the first surface; a special stirring head is used to weld the copper alloy piece by piece according to the parts that need to be welded, and the aluminum alloy is locally forced to cool. The special stirring head is based on the traditional stirring head with the following changes: (1) The stirring pin is divided into three sections in the length H direction. The head and root 1 / 4 H area are conventional right-handed single spiral morphology, and the middle 1 / 2 H area is concave wave morphology in the up-down direction. This increases the turbulent stirring effect and the contact area between dissimilar metals during copper-aluminum interface welding, and improves the weld strength after copper-aluminum friction lap welding; (2) The stirring pin has a smaller taper than the conventional stirring pin, and the overall diameter W is more than 30% larger than the conventional stirring pin. This ensures uniform heat generation at the interface during welding and improves the efficiency of friction lap welding. The third step involves copper-aluminum friction stir welding on the second side, using the same welding method as the second step. Step 4: Finishing of copper-aluminum composite busbar; The copper alloy on the welded surface is machined to retain a copper alloy layer of a set thickness; Step 5: Apply powder coating to the surface of the copper-aluminum composite busbar for protection.

2. The method according to claim 1, characterized in that, In the first step, the aluminum alloy material is 5-series aluminum alloy, and the busbar thickness is 10-12mm.

3. The method according to claim 1, characterized in that, In the second step, the copper alloy material is T2 copper with a thickness of 2.5-3mm.

4. The method according to claim 1, characterized in that, In the second step, when welding each section, the width of each weld is W, the overlap area is 1 / 4W, the welding speed is 100-200mm / s, the rotation speed is 1000-2000r / min, and X-ray inspection is performed after welding to prevent internal defects.

5. The method according to claim 1, characterized in that, In the second step, the forced cooling of the aluminum alloy in a localized area specifically involves using tooling and an external cooling source to locally cool only the aluminum alloy below the weld, preventing the aluminum alloy from melting due to excessively high temperature during copper-aluminum welding, which could lead to welding defects.

6. The method according to claim 1, characterized in that, In the fourth step, the set thickness is 1-1.5mm.

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