Forming process of copper-clad aluminum wire with high interface bonding rate

Abstract

The invention belongs to the technical field of copper-clad aluminum wire manufacturing, and discloses a high-interface bonding rate copper-clad aluminum wire forming process which comprises the following steps: S1, raw material preparation and pretreatment: a, aluminum rod and copper strip preparation: processing and slitting an aluminum rod and a copper strip; the bonding strength and quality between the copper layer and the aluminum core are remarkably improved through electric field assisted bonding treatment, the diffusion process between copper atoms and aluminum atoms can be accelerated through the electric field, bonding between the copper layer and the aluminum core is tighter, and the effect of the electric field is similar to a driving force; according to the copper-clad aluminum wire forming process, atoms can cross an energy barrier more easily under the action of electric field force, so that more efficient combination is achieved, interaction force between the atoms is enhanced under the action of an electric field, the interface bonding force is improved, and the copper-clad aluminum wire forming process under the assistance of the electric field can remarkably improve the bonding strength between a copper layer and an aluminum core; therefore, the high interface bonding rate is greatly improved, and the interface bonding between the copper layer and the aluminum core is firmer and more stable.

Description

Technical Field

[0001] The invention belongs to the technical field of copper clad aluminum wire manufacturing, and in particular relates to a forming process for copper clad aluminum wire with high interface bonding rate. Background Art

[0002] Copper clad aluminum wire (CCA) is a bimetallic composite conductor with stable performance obtained by concentrically coating a layer of copper strip of equal thickness on an aluminum core to form a metallurgical bond during the drawing process.

[0003] In the prior art copper-clad aluminum forming and preparation process, copper and aluminum are very easy to oxidize in the atmosphere to form an oxide film, especially aluminum, whose surface forms an aluminum oxide (Al2O3) film at room temperature. In the production process of copper-clad aluminum wire, the oxides on the surface of the copper strip and the aluminum rod are not thoroughly cleaned and brushed, or the argon protection in the coating welding device is not in place, which will lead to residual oxide film, thereby affecting the interface bonding rate, resulting in the finished product performance of the copper-clad aluminum wire after preparation is often unstable, including resistivity fluctuations, reduced tensile strength, reduced corrosion resistance, etc., and the actual forming quality is poor. Summary of the invention

[0004] The object of the present invention is to provide a high interface bonding rate copper clad aluminum wire forming process to solve the problems raised in the above background technology.

[0005] In order to achieve the above object, the present invention provides the following technical solution: a high interface bonding rate copper clad aluminum wire forming process, comprising the following steps:

[0006] S1. Raw material preparation and pretreatment:

[0007] a. Preparation of aluminum rod and copper strip: Process and cut aluminum rod and copper strip, select electrolytic aluminum rod with purity higher than 99%, diameter range is Φ2.0mm to Φ10.0mm, select electrolytic copper strip with purity higher than 99.9%, width range is 5mm to 50mm, thickness range is 0.1mm to 1.0mm;

[0008] b. Surface cleaning: Brush the surface of the aluminum rod and copper strip to remove surface oxides and oil stains;

[0009] c Plasma surface modification: After cleaning the aluminum rod and copper strip, plasma is used to bombard and etch the metal surface to form a new, more active surface layer;

[0010] S2. Coating and electric field assisted combination:

[0011] a. Overmolding: The pre-treated aluminum rod and copper strip are fed into the overmolding device, and the copper strip is tightly overmolded on the aluminum rod by hydraulic means, with an overmolding speed ranging from 5 to 30 m / min;

[0012] b Electric field assisted bonding: Immediately after overmolding, a specific electric field is applied at the inlet and outlet of the drawing die, and the attraction and repulsion of metal ions by the electric field causes atomic diffusion and preliminary bonding between the copper layer and the aluminum core;

[0013] S3, drawing and low temperature solid diffusion welding:

[0014] a Precision drawing: The copper-clad aluminum wire after electric field assisted bonding is fed into the drawing machine, and the drawing speed, die angle, diameter reduction and other parameters are precisely controlled to draw the wire so that the interface between the copper layer and the aluminum core is further squeezed and diffused;

[0015] b Low-temperature solid-state diffusion welding: During the drawing process, the copper-clad aluminum wire is subjected to low-temperature solid-state diffusion welding. Pressure is applied and at a temperature below the melting point of copper and aluminum, the atoms between the copper layer and the aluminum core undergo solid-state diffusion and bonding;

[0016] S4. Subsequent processing and testing:

[0017] a. Heat treatment: heat treatment is performed on the copper-clad aluminum wire after drawing and welding to eliminate internal stress;

[0018] b. Eddy current flaw detection: Eddy current flaw detection is performed on the copper clad aluminum wire after heat treatment to detect whether there are defects inside the wire;

[0019] c. Cleaning and wire collection: Clean the qualified copper-clad aluminum wire to remove the oil and impurities on the surface, and then collect and package it;

[0020] d Final inspection: Conduct final mechanical and electrical performance tests on the finished copper-clad aluminum wire to ensure that it meets the use requirements.

[0021] Preferably, in S1, the plasma treatment time ranges from 10 to 60 seconds, the treatment power ranges from 100 to 500 W, the working gas is argon, and the gas flow rate is 5 to 20 L / min.

[0022] Preferably, in S1, mechanical brushing uses a stainless steel wire brush to brush the surface of the aluminum rod and the copper strip at a speed of 50-150rpm to remove surface oxides and oil stains; chemical cleaning uses an alkaline cleaning agent to soak at a temperature of 50-80°C for 5-10 minutes, then rinse with clean water, and use a weak acid cleaning agent to further clean the copper strip and remove surface oxides.

[0023] Preferably, the alkaline cleaning agent is sodium hydroxide solution, and the weakly acidic cleaning agent is dilute sulfuric acid.

[0024] Preferably, the plasma source is a radio frequency induction plasma source, the plasma treatment time ranges from 10 to 60 seconds, the treatment power ranges from 100 to 500 W, the working gas is argon, and the gas flow rate is 5 to 20 L / min.

[0025] Preferably, the plasma source is a DC arc plasma source, the plasma processing time ranges from 15 to 65 seconds, the processing power ranges from 120 to 504 W, the working gas is nitrogen, and the gas flow rate is 5 to 20 L / min.

[0026] Preferably, in S2, the electric field strength ranges from 10 to 100 kV / cm, the electric field direction is perpendicular to the interface between the copper layer and the aluminum core, and the electric field assisted bonding time ranges from 1 to 10 seconds.

[0027] Preferably, in S3, the drawing die is a cemented carbide die, the drawing speed ranges from 5 to 50 m / min, and the drawing ratio (the ratio of the diameter of the wire after drawing to the original diameter) is controlled between 1.1 and 3.0.

[0028] Preferably, in S4, the heat treatment temperature ranges from 200 to 400° C., the heat treatment time ranges from 1 to 4 hours, the eddy current flaw detector is a high-frequency eddy current flaw detector, the detection frequency ranges from 100 kHz to 1 MHz, and the detection speed is between 1 and 10 m / s.

[0029] The beneficial effects of the present invention are as follows:

[0030] 1. The present invention significantly improves the bonding strength and quality between the copper layer and the aluminum core through electric field assisted bonding treatment. The electric field can accelerate the diffusion process between copper atoms and aluminum atoms, making the bonding between the copper layer and the aluminum core tighter. The effect of the electric field is similar to a driving force, making it easier for atoms to cross the energy barrier under the action of the electric field force, thereby achieving more efficient bonding. Under the action of the electric field, the interaction force between atoms is enhanced, thereby improving the bonding force of the interface. The copper clad aluminum wire forming process assisted by the electric field can significantly improve the bonding strength between the copper layer and the aluminum core, thereby achieving a greatly improved high interface bonding rate, and the interface bonding between the copper layer and the aluminum core is more firm and stable.

[0031] 2. The present invention effectively cleans the interface between the copper layer and the aluminum core through plasma treatment, removes surface pollutants and oxide layers, thereby exposing a fresh metal surface and enhancing the atomic bonding force between the copper layer and the aluminum core. The plasma treatment can also form a dense oxide film on the metal surface, which helps to promote atomic diffusion between the copper layer and the aluminum core during the subsequent heat treatment process, further improving the bonding strength of the interface. The plasma treatment also has the effects of improving the surface roughness of the wire, improving the surface wettability and enhancing the surface activity, which is beneficial to the subsequent drawing and forming processes, ensuring that the wire is not easy to break during the drawing process and has excellent mechanical and electrical properties after forming. DETAILED DESCRIPTION

[0032] Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without making any creative work shall fall within the scope of protection of the present invention.

[0033] The embodiment of the present invention provides a high interface bonding rate copper clad aluminum wire forming process, comprising the following steps:

[0034] S1. Raw material preparation and pretreatment:

[0035] a. Preparation of aluminum rod and copper strip: Process and cut aluminum rod and copper strip, select electrolytic aluminum rod with purity higher than 99%, diameter range is Φ2.0mm to Φ10.0mm, select electrolytic copper strip with purity higher than 99.9%, width range is 5mm to 50mm, thickness range is 0.1mm to 1.0mm;

[0036] b. Surface cleaning: Brush the surface of the aluminum rod and copper strip to remove surface oxides and oil stains;

[0037] c Plasma surface modification: After cleaning the aluminum rod and copper strip, plasma is used to bombard and etch the metal surface to form a new, more active surface layer;

[0038] S2. Coating and electric field assisted combination:

[0039] a. Overmolding: The pre-treated aluminum rod and copper strip are fed into the overmolding device, and the copper strip is tightly overmolded on the aluminum rod by hydraulic means, with an overmolding speed ranging from 5 to 30 m / min;

[0040] b Electric field assisted bonding: Immediately after overmolding, a specific electric field is applied at the inlet and outlet of the drawing die, and the attraction and repulsion of metal ions by the electric field causes atomic diffusion and preliminary bonding between the copper layer and the aluminum core;

[0041] S3, drawing and low temperature solid diffusion welding:

[0042] a Precision drawing: The copper-clad aluminum wire after electric field assisted bonding is fed into the drawing machine, and the drawing speed, die angle, diameter reduction and other parameters are precisely controlled to draw the wire so that the interface between the copper layer and the aluminum core is further squeezed and diffused;

[0043] b Low-temperature solid-state diffusion welding: During the drawing process, the copper-clad aluminum wire is subjected to low-temperature solid-state diffusion welding. Pressure is applied and at a temperature below the melting point of copper and aluminum, the atoms between the copper layer and the aluminum core undergo solid-state diffusion and bonding;

[0044] S4. Subsequent processing and testing:

[0045] a. Heat treatment: heat treatment is performed on the copper-clad aluminum wire after drawing and welding to eliminate internal stress;

[0046] b. Eddy current flaw detection: Eddy current flaw detection is performed on the copper clad aluminum wire after heat treatment to detect whether there are defects inside the wire;

[0047] c. Cleaning and wire collection: Clean the qualified copper-clad aluminum wire to remove the oil and impurities on the surface, and then collect and package it;

[0048] d Final inspection: Conduct final mechanical and electrical performance tests on the finished copper-clad aluminum wire to ensure that it meets the use requirements.

[0049] Among them, in S1, the plasma treatment time range is 10-60 seconds, the treatment power range is 100-500W, the working gas is argon, the gas flow rate is 5-20L / min, and the mechanical brushing uses a stainless steel wire brush to brush the surface of the aluminum rod and the copper belt at a speed of 50-150rpm to remove surface oxides and oil stains; chemical cleaning uses an alkaline cleaning agent to soak at a temperature of 50-80°C for 5-10 minutes, then rinse with clean water, and use a weak acid cleaning agent to further clean the copper belt and remove surface oxides. The alkaline cleaning agent is sodium hydroxide solution and the weak acid cleaning agent is dilute sulfuric acid.

[0050] By setting the parameters of time range, processing power, working gas and gas flow, it is ensured that the plasma has enough time to react with the material surface. The power selection affects the intensity and activity of the plasma, which in turn affects the treatment effect. The plasma is stabilized by inert gas and chemical reactions with the material are avoided. The gas flow affects the uniformity and stability of the plasma. The main purpose of plasma treatment is to remove oxides and oil stains on the surface of aluminum rods and copper strips, and to increase the surface roughness, thereby improving the bonding between copper and aluminum.

[0051] Stainless steel wire brushes are wear-resistant and corrosion-resistant and are suitable for brushing metal surfaces. Mechanical brushing can further remove surface residues and increase surface roughness, providing good conditions for subsequent chemical cleaning and copper cladding. Sodium hydroxide solution neutralizes surface acidic substances and removes oil and oxides. The temperature of 50-80°C improves the activity and cleaning effect of the cleaning agent. The cleaning time of 5-10 minutes ensures that the cleaning agent has enough time to react with the material surface. Dilute sulfuric acid is used for further cleaning of the copper strip to remove surface oxides and residues. Chemical cleaning can completely remove surface pollutants without damaging the material.

[0052] Embodiment 1: The plasma source is a radio frequency induction plasma source, the plasma treatment time ranges from 10 to 60 seconds, the treatment power ranges from 100 to 500 W, the working gas is argon, and the gas flow rate is 5 to 20 L / min.

[0053] DC arc plasma can produce high-density plasma, which is suitable for rapid and effective treatment of material surfaces, ensuring the continuity and stability of the plasma.

[0054] Embodiment 2: The plasma source is a DC arc plasma source, the plasma treatment time ranges from 15 to 65 seconds, the treatment power ranges from 120 to 504 W, the working gas is nitrogen, and the gas flow rate is 5 to 20 L / min.

[0055] DC arc technology enables particles in the plasma to obtain higher speeds and energy, thereby reacting with the surface of materials more quickly. Nitrogen is also an inert gas, and its chemical properties may be more active. It can undergo slight chemical reactions with the surface of materials under certain conditions, thereby improving the surface of the materials.

[0056] Among them, in S2, the electric field strength ranges from 10 to 100 kV / cm, the electric field direction is perpendicular to the interface between the copper layer and the aluminum core, and the electric field assisted bonding time ranges from 1 to 10 seconds.

[0057] The electric field can accelerate the diffusion process between copper atoms and aluminum atoms, making the bonding between the copper layer and the aluminum core tighter. The role of the electric field is similar to a driving force, making it easier for atoms to cross the energy barrier under the action of the electric field force, thereby achieving more efficient bonding. Under the action of the electric field, the interaction force between atoms is enhanced, thereby improving the bonding strength of the interface. The copper-clad aluminum wire forming process assisted by the electric field can significantly improve the bonding strength between the copper layer and the aluminum core.

[0058] The direction of the electric field is perpendicular to the interface between the copper layer and the aluminum core, which is conducive to the electric field force acting directly on the atoms on the interface, promoting their diffusion and bonding. The choice of direction ensures that the electric field can play its role to the maximum extent and improve the bonding efficiency. The electric field assisted bonding time range is 1-10 seconds, which ensures that the electric field has enough time to promote the bonding between the copper layer and the aluminum core. At the same time, it also avoids unnecessary energy consumption and possible material damage caused by too long a time.

[0059] Among them, in S3, the drawing die is a cemented carbide die, the drawing speed range is 5-50m / min, and the drawing ratio (the ratio of the diameter of the wire after drawing to the original diameter) is controlled between 1.1-3.0.

[0060] Carbide dies have extremely high wear resistance and hardness, and can withstand the friction and pressure generated during high-speed drawing, ensuring that the wire maintains a stable shape and size during the drawing process. The wear resistance of carbide dies helps to extend the service life of the dies and reduce the frequency of die replacement, thereby improving production efficiency and reducing costs.

[0061] When the drawing speed range is 5-50m / min, it ensures that the wire can be fully deformed during the drawing process, while avoiding wire breakage caused by too fast speed or low production efficiency caused by too slow speed. When drawing at low speed, the drawing force increases with the increase of drawing speed. When the drawing speed increases to a certain range (such as 6-50m / min), the drawing force will decrease. Since the wire is more likely to produce plastic deformation under high-speed drawing, too high a drawing speed may also cause the surface quality of the wire to decrease. Therefore, it is necessary to draw within an appropriate speed range.

[0062] Controlling the drawing ratio between 1.1-3.0 ensures that the wire can obtain the appropriate degree of deformation during the drawing process, thereby achieving the desired diameter and shape.

[0063] Among them, in S4, the heat treatment temperature range is 200-400°C, the heat treatment time range is 1-4 hours, the eddy current flaw detector is a high-frequency eddy current flaw detector, the detection frequency range is 100kHz to 1MHz, and the detection speed is between 1-10m / s.

[0064] Controlling the heat treatment temperature between 200-400℃ helps promote the diffusion of atoms between the copper layer and the aluminum core, thereby enhancing the bonding strength between them. At the same time, the appropriate temperature can also eliminate the internal stress generated during the drawing process and improve the toughness of the wire. The heat treatment time is controlled between 1-4 hours to ensure that the atoms between the copper layer and the aluminum core have enough time to diffuse and combine, thereby achieving a high interface bonding rate.

[0065] The use of high-frequency eddy current flaw detectors can achieve non-destructive testing of surface and internal defects of copper-clad aluminum wires. High-frequency eddy currents can penetrate the surface of wires and detect internal defects such as tiny cracks and inclusions. The detection frequency range is between 100kHz and 1MHz. This frequency range ensures that eddy current flaw detectors can detect defects of different sizes and depths. At the same time, high-frequency eddy currents also have higher sensitivity and resolution, which can more accurately locate the position and size of defects, and the detection speed is between 1-10m / s, which ensures that eddy current flaw detectors can efficiently detect wires.

[0066] Although 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 the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A high interface bonding rate copper clad aluminum wire forming process, characterized by: The following steps are involved: S1. Raw material preparation and pretreatment: a. Preparation of aluminum rod and copper strip: Process and cut aluminum rod and copper strip, select electrolytic aluminum rod with purity higher than 99%, diameter range is Φ2.0mm to Φ10.0mm, select electrolytic copper strip with purity higher than 99.9%, width range is 5mm to 50mm, thickness range is 0.1mm to 1.0mm; b. Surface cleaning: Brush the surface of the aluminum rod and copper strip to remove surface oxides and oil stains; c Plasma surface modification: After cleaning the aluminum rod and copper strip, plasma is used to bombard and etch the metal surface to form a new, more active surface layer; S2. Coating and electric field assisted combination: a. Overmolding: The pre-treated aluminum rod and copper strip are fed into the overmolding device, and the copper strip is tightly overmolded on the aluminum rod by hydraulic means, with an overmolding speed ranging from 5 to 30 m / min; b Electric field assisted bonding: Immediately after overmolding, a specific electric field is applied at the inlet and outlet of the drawing die, and the attraction and repulsion of metal ions by the electric field causes atomic diffusion and preliminary bonding between the copper layer and the aluminum core; S3, drawing and low temperature solid diffusion welding: a Precision drawing: The copper-clad aluminum wire after electric field assisted bonding is fed into the drawing machine, and the drawing speed, die angle, diameter reduction and other parameters are precisely controlled to draw the wire so that the interface between the copper layer and the aluminum core is further squeezed and diffused; b Low-temperature solid-state diffusion welding: During the drawing process, the copper-clad aluminum wire is subjected to low-temperature solid-state diffusion welding. Pressure is applied and at a temperature below the melting point of copper and aluminum, the atoms between the copper layer and the aluminum core undergo solid-state diffusion and bonding; S4. Subsequent processing and testing: a. Heat treatment: heat treatment is performed on the copper-clad aluminum wire after drawing and welding to eliminate internal stress; b. Eddy current flaw detection: Eddy current flaw detection is performed on the copper clad aluminum wire after heat treatment to detect whether there are defects inside the wire; c. Cleaning and wire collection: Clean the qualified copper-clad aluminum wire to remove the oil and impurities on the surface, and then collect and package it; d Final inspection: Conduct final mechanical and electrical performance tests on the finished copper-clad aluminum wire to ensure that it meets the use requirements.

2. A high interface bonding rate copper clad aluminum wire forming process according to claim 1, characterized in that: In S1, the plasma treatment time ranges from 10 to 60 seconds, the treatment power ranges from 100 to 500 W, the working gas is argon, and the gas flow rate is 5 to 20 L / min.

3. A high interface bonding rate copper clad aluminum wire forming process according to claim 2, characterized in that: In S1, mechanical brushing uses a stainless steel wire brush to brush the surface of the aluminum rod and the copper strip at a speed of 50-150rpm to remove surface oxides and oil stains; chemical cleaning uses an alkaline cleaning agent to soak at a temperature of 50-80°C for 5-10 minutes, then rinse with clean water, and use a weak acid cleaning agent to further clean the copper strip and remove surface oxides.

4. A high interface bonding rate copper clad aluminum wire forming process according to claim 3, characterized in that: The alkaline cleaning agent is sodium hydroxide solution, and the weakly acidic cleaning agent is dilute sulfuric acid.

5. A high interface bonding rate copper clad aluminum wire forming process according to claim 4, characterized in that: The plasma source is a radio frequency induction plasma source, the plasma processing time ranges from 10 to 60 seconds, the processing power ranges from 100 to 500 W, the working gas is argon, and the gas flow rate is 5 to 20 L / min.

6. A high interface bonding rate copper clad aluminum wire forming process according to claim 4, characterized in that: The plasma source is a DC arc plasma source, the plasma processing time ranges from 15 to 65 seconds, the processing power ranges from 120 to 504 W, the working gas is nitrogen, and the gas flow rate is 5 to 20 L / min.

7. A high interface bonding rate copper clad aluminum wire forming process according to claim 1, characterized in that: In S2, the electric field strength ranges from 10 to 100 kV / cm, the electric field direction is perpendicular to the interface between the copper layer and the aluminum core, and the electric field assisted bonding time ranges from 1 to 10 seconds.

8. The high interface bonding rate copper clad aluminum wire forming process according to claim 1, characterized in that: In S3, the drawing die is a cemented carbide die, the drawing speed ranges from 5 to 50 m / min, and the drawing ratio (the ratio of the diameter of the wire after drawing to the original diameter) is controlled between 1.1 and 3.

0.

9. The high interface bonding rate copper clad aluminum wire forming process according to claim 1, characterized in that: In S4, the heat treatment temperature range is 200-400° C., the heat treatment time range is 1-4 hours, the eddy current flaw detector is a high-frequency eddy current flaw detector, the detection frequency range is 100kHz to 1MHz, and the detection speed is between 1-10m / s.