Manufacturing process of aluminum-clad steel composite automobile wire

Abstract

The invention discloses a manufacturing process of an aluminum-clad steel composite automobile wire, which solves the problems of high copper consumption, high cost, imperfection of an aluminum strip copper scheme in a low-voltage loop, limited application of an aluminum-clad steel scheme in an automobile cable, low cost and the like in the prior art through the steps of material selection and optimization, cladding, wire drawing, terminal connection and welding. And problems exist in the welding process of the aluminum wire in the connector. According to the aluminum-clad steel composite automobile wire manufactured by the process, on the premise of ensuring the conductivity, the copper consumption is further reduced, the mechanical strength is improved, the corrosion resistance is enhanced, meanwhile, a reliable connection solution is provided, the production cost is reduced, the overall performance of an automobile wire harness is improved, and the service life of the automobile wire harness is prolonged.

Description

Technical Field

[0001] The invention belongs to the technical field of wire and cable manufacturing, and particularly relates to a manufacturing process for an aluminum-clad steel composite automotive wire. Background Art

[0002] In today's rapidly developing automotive industry, automotive wiring harnesses, as a key component of the vehicle's electrical system, have a significant impact on the competitiveness of the vehicle due to their performance and cost. In recent years, copper prices have continued to rise, and environmental protection requirements have become increasingly stringent, making the development of new automotive wiring harness materials and technologies an urgent need in the industry.

[0003] Currently, conventional weight reduction solutions utilize copper-clad steel technology, achieving a 60% reduction in copper content and a 30% reduction in weight in wiring harnesses, achieving certain cost reductions and efficiency gains. However, this technology still has room for further reductions in copper usage, and the implementation of aluminum-copper strips in low-voltage circuits is still incomplete. The application of aluminum-clad steel solutions in automotive cables also faces numerous challenges.

[0004] On the one hand, aluminum wire is prone to problems during connector soldering. Aluminum is chemically reactive and easily oxidizes in air, forming a dense aluminum oxide film. This film has a high resistivity, which can seriously affect welding quality, increase contact resistance, and even cause weak welds. On the other hand, existing aluminum-clad steel wire manufacturing processes make it difficult to ensure the bond strength between the aluminum layer and the steel core, as well as the stability of the overall electrical conductivity and mechanical properties of the cable, in automotive cable applications. Summary of the Invention

[0005] To solve the above problems, the present invention provides a manufacturing process for aluminum-clad steel composite automotive wire, comprising the following steps: S1. Material Selection and Optimization: An aluminum alloy with excellent electrical conductivity and corrosion resistance is selected as the outer cladding material, and its composition is adjusted through alloying design. A high-strength steel wire is used as the core material, and surface treatment is performed. S2. Cladding: The aluminum alloy is clad on the surface of the steel wire using the CONCLAD extrusion method, with precise control of temperature, pressure, and speed parameters and optimized die structure; S3. Wire drawing: Wire drawing of aluminum-clad steel composite wire is performed, selecting appropriate lubricants and drawing dies, and controlling the drawing speed and deformation; S4. Terminal connection: Develop terminal connection technology specifically for aluminum-clad steel composite automotive cables, design new terminal structures, and adopt special crimping processes; S5. Welding: Weld the aluminum-clad steel composite wire, optimize welding parameters, and control heat input during welding.

[0006] Preferably, magnesium and silicon are added to the aluminum alloy in step S1, and heat treatment is performed to improve its microstructure; wherein the magnesium content is 0.5% - 2%, and the silicon content is 0.3% - 1%.

[0007] Preferably, the surface treatment method of the steel wire in step S1 is copper plating, and the thickness of the copper plating layer is 5-15 μm.

[0008] Preferably, in the coating process of step S2, the extrusion temperature is 450° C.-500° C., the pressure is 50 MPa-100 MPa, and the speed is 5-10 m / min.

[0009] Preferably, in the wire drawing process of step S3, the lubricant is a mineral oil-based lubricant or a synthetic lubricant, and the material of the wire drawing die is a cemented carbide or diamond.

[0010] Preferably, in the terminal connection in step S4, the crimping process is hot crimping, and the hot crimping is maintained at a temperature of 150° C. to 200° C. and a pressure of 15 to 25 kN.

[0011] Preferably, in step S5, the welding technique is resistance welding, the resistance welding current is 5-10 kA, and the duration is 0.1-0.3 s.

[0012] The beneficial effects of the present invention are: This aluminum-clad steel composite automotive cable combines the excellent conductivity of aluminum with the high strength of steel, achieving an optimized combination of electrical and mechanical properties. Compared to traditional pure copper automotive cables, this significantly improves mechanical strength while maintaining electrical conductivity, better adapting to the complex automotive operating environment.

[0013] Through the CONCLAD extrusion and wire drawing process, we achieve efficient and high-quality production of aluminum-clad steel composite automotive wire. The optimized production process improves production efficiency and reduces production costs, laying the foundation for large-scale industrial production.

[0014] Through terminal connection and welding technology, we provide a reliable connection solution for aluminum-clad steel composite automotive cables. The new terminal structure and crimping process, as well as optimized welding parameters, effectively improve the reliability and stability of the connection, reduce contact resistance, and minimize the probability of electrical failure. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 Schematic diagram of the method of the present invention. DETAILED DESCRIPTION

[0016] The technical solutions in the embodiments of the present invention will be described clearly and completely below with reference to the accompanying drawings in the embodiments of the present invention.

[0017] In accordance with design requirements, an aluminum alloy with excellent electrical conductivity and corrosion resistance was selected as the cladding material. Through alloying design, the aluminum alloy's composition was adjusted, such as by adding elements such as magnesium and silicon, to improve its strength and electrochemical corrosion resistance. The addition of magnesium refines the aluminum alloy's grain size, enhancing its strength and toughness; the addition of silicon forms a strengthening phase, further increasing the alloy's strength. Adding 1% magnesium and 0.8% silicon to the aluminum alloy significantly improves its overall performance. Simultaneously, the aluminum alloy undergoes heat treatment to improve its microstructure and enhance its overall performance. For example, a combination of solution treatment and aging treatment is employed: the solution treatment temperature is controlled at 530°C for 1.5 hours, followed by aging treatment at 170°C for 6 hours. This allows the alloying elements in the aluminum alloy to fully dissolve and precipitate strengthening phases, thereby improving the alloy's strength and hardness.

[0018] High-strength steel wire is used as the core material to provide mechanical support for the composite wire. The steel wire is surface-treated with copper plating to enhance its bond with the aluminum layer while reducing the risk of electrochemical corrosion. This copper plating creates a uniform copper layer on the steel wire surface. Copper and aluminum have a good affinity, strengthening the bond between the aluminum layer and the steel core. Steel wire of the appropriate strength grade, with a tensile strength of 1600 MPa, is selected to minimize its impact on electrical conductivity while maintaining the mechanical properties of the composite wire. The steel wire undergoes pre-treatment, including drawing and heat treatment, to achieve the desired strength and surface finish. For example, the aluminum alloy smelting process requires strict temperature and composition control to ensure consistent quality. The wire drawing process gradually reduces the wire diameter to improve its strength and surface finish. The compression ratio is controlled at 22% per drawing pass, and the heat treatment temperature is kept at 450°C for 1.5 hours.

[0019] The pre-treated aluminum alloy and steel wire are fed into the CONCLAD extruder. This machine utilizes continuous extrusion and cladding technology. Its operating principle combines continuous extrusion with cladding processes, achieving continuous deformation and cladding of the metal through friction and pressure. Billet Feeding: Metal rods or pellets are continuously fed into the extrusion chamber by the friction of the extrusion wheels. Frictional Heating and Plastic Deformation: Friction between the extrusion wheels and the billet generates heat, softening the metal. Simultaneously, the rotation of the extrusion wheels applies pressure, propelling the billet through the die. Overmolding: In the die area, the metal billet wraps around the core wire, forming a composite material. The die shape and dimensions determine the thickness and uniformity of the cladding layer. Cooling and Winding: The formed product solidifies in a cooling unit before being wound into a coil, cladding the steel wire with the aluminum alloy. During the extrusion process, precise control of parameters such as temperature, pressure, and speed ensures a tight bond between the aluminum layer and the steel core, without gaps or defects. Excessively high extrusion temperatures can cause the aluminum alloy to melt, while excessively low temperatures can complicate extrusion and compromise the quality of the aluminum layer. Typically, the extrusion temperature is controlled at 480°C, the pressure at 75 MPa, and the speed at 7 m / min. Optimizing the die design ensures the dimensional accuracy and surface quality of the aluminum-clad steel composite wire. The die shape and dimensions are precisely designed according to the specifications of the composite wire, with the die entry angle controlled at 45° and the die exit angle at 5° to ensure that the composite wire's outer diameter, wall thickness, and other dimensions meet the required specifications. After extrusion, the clad composite wire undergoes a preliminary inspection to check the bond between the aluminum layer and the steel core, as well as the surface quality. An ultrasonic flaw detector is used to test the bond between the aluminum layer and the steel core to ensure the absence of defects such as delamination and bubbles. A surface roughness tester is used to test the composite wire's surface roughness to ensure it meets the required specifications.

[0020] Feed the coated composite wire into the wire drawing machine, and select the appropriate lubricant and drawing die. The aluminum-clad steel composite wire is drawn to further improve its strength and surface finish. During the wire drawing process, select the appropriate lubricant and drawing die, control the drawing speed and deformation, and avoid problems such as separation of the aluminum layer and the steel core and brittle fracture of the composite wire. The lubricant can be a mineral oil-based lubricant or a synthetic lubricant with good lubrication and cooling properties. The material of the wire drawing die can be cemented carbide or diamond, and the appropriate die aperture and taper are selected according to the material and specifications of the composite wire. The drawing speed is controlled at 7m / min and the deformation is controlled at 15%. After the wire drawing is completed, the composite wire is cleaned and dried to remove the lubricant and impurities on the surface. In this embodiment, an organic solvent is used to clean the lubricant on the surface of the composite wire, and then it is dried with hot air, and the drying temperature is controlled at 90°C.

[0021] Design and manufacture new terminals based on the specifications and connection requirements of aluminum-clad steel composite automotive cables. Develop terminal connection technology specifically for aluminum-clad steel composite automotive cables. Design a new terminal structure to increase the contact area between the terminal and the composite cable and enhance connection reliability. The new terminal can adopt a special design, such as increasing the number of teeth or changing the shape of the teeth, to increase the contact area with the composite cable. In this example, a terminal with seven trapezoidal teeth was designed. A hot press bonding process was used to ensure the electrical and mechanical properties of the connection. A higher temperature was used to better bond the terminal to the composite cable, enhancing connection strength. The hot press bonding temperature was controlled at 180°C and the pressing pressure was controlled at 20 kN. After the crimping process was completed, the connection was tested for electrical and mechanical properties to verify the connection quality. In this example, a tensile tester was used to test the mechanical strength of the connection, requiring a pull-out force of no less than 50 N. A resistance tester was used to test the contact resistance of the connection, requiring no more than 0.1 mΩ.

[0022] When welding aluminum-clad steel composite automotive wire, the appropriate welding technology is selected based on the actual situation. In this case, resistance welding is chosen. By optimizing welding parameters and controlling heat input during welding, the melting of the aluminum layer and overheating of the steel core are avoided, thereby ensuring the quality and performance of the welded joint. During resistance welding, parameters such as welding current, welding time, and electrode pressure must be appropriately selected. The welding current should be controlled at 7kA, the welding time at 0.2s, and the electrode pressure at 7kN. After welding, the welded joint is quality inspected to ensure that its strength and conductivity meet the requirements. The microstructure of the welded joint is observed using a metallographic microscope to check for defects such as cracks and pores. The tensile strength of the welded joint is tested using a tensile testing machine, which must be no less than 90% of the strength of the composite wire itself.

[0023] Completed aluminum-clad steel composite automotive wire undergoes comprehensive inspection, including testing for dimensional accuracy, surface quality, electrical performance, and mechanical properties. Only qualified products are packaged. Appropriate packaging materials and methods should be used to protect the product from damage during transportation and storage. For example, moisture-proof and shock-resistant packaging materials should be used, the composite wire should be neatly coiled, and then placed in a box filled with cushioning material.

[0024] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A manufacturing process for aluminum-clad steel composite automotive wire, characterized in that: The following steps are involved: S1. Material Selection and Optimization: An aluminum alloy with good electrical conductivity and corrosion resistance was selected as the outer cladding material, and its composition was adjusted through alloying design. Use high-strength steel wire as the core material and perform surface treatment; S2. Cladding: The aluminum alloy is clad on the surface of the steel wire using the CONCLAD extrusion method, with precise control of temperature, pressure, and speed parameters and optimized die structure; S3. Wire drawing: Wire drawing of aluminum-clad steel composite wire is performed, selecting appropriate lubricants and drawing dies, and controlling the drawing speed and deformation; S4. Terminal connection: Develop terminal connection technology specifically for aluminum-clad steel composite automotive cables, design new terminal structures, and adopt special crimping processes; S5. Welding: Weld the aluminum-clad steel composite wire, optimize welding parameters, and control heat input during welding.

2. The manufacturing process of the aluminum-clad steel composite automotive wire according to claim 1, characterized in that: In step S1, magnesium and silicon elements are added to the aluminum alloy, and heat treatment is performed to improve its microstructure; wherein the magnesium content is 0.5%-2%, and the silicon content is 0.3%-1%.

3. The manufacturing process of the aluminum-clad steel composite automotive wire according to claim 1, characterized in that: The surface treatment method of the steel wire in step S1 is copper plating, and the thickness of the copper plating layer is 5-15 μm.

4. The manufacturing process of the aluminum-clad steel composite automotive wire according to claim 1, characterized in that: In the coating process of step S2, the extrusion temperature is 450° C.-500° C., the pressure is 50 MPa-100 MPa, and the speed is 5-10 m / min.

5. The manufacturing process of the aluminum-clad steel composite automotive wire according to claim 1, characterized in that: In the wire drawing process of step S3, the lubricant is a mineral oil-based lubricant or a synthetic lubricant, and the material of the wire drawing die is a cemented carbide or diamond.

6. The manufacturing process of the aluminum-clad steel composite automotive wire according to claim 1, characterized in that: In the terminal connection described in step S4, the crimping process is hot crimping, and the hot crimping is maintained at a temperature of 150° C. to 200° C. and a pressure of 15 to 25 kN.

7. The manufacturing process of the aluminum-clad steel composite automotive wire according to claim 1, characterized in that: In step S5, the welding technique is resistance welding, the resistance welding current is 5-10 kA, and the duration is 0.1-0.3 s.

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