Method and device for manufacturing double-layer metal composite wire

Abstract

The present invention relates to the technical field of metal composite wires, and in particular, to a method and device for manufacturing a double-layer metal composite wire. The manufacturing method comprises the following steps: S1. taking a double-layer metal composite billet, comprising a core metal wire and a metal cladding layer coated on the outside of the core metal wire, wherein the tensile strength of the metal cladding layer is greater than that of the core metal wire; S2. performing multiple drawing on the double-layer metal composite billet to obtain a composite metal wire, and applying a pulse current to the metal cladding layer located in the drawing zone during the drawing process to match the mechanical properties of the metal cladding layer with those of the core metal wire, thereby suppressing interface fracture; S3. annealing the composite metal wire to obtain the composite wire. The present invention controls the pulse current parameters, utilizes the skin effect and electroplastic properties to achieve the effect of softening only the metal cladding layer, makes the inner and outer metals draw-deformed in the same manner, and improves the quality of the composite wire. In addition, the method is applicable to the case where the electrical conductivity of the inner metal layer is greater than that of the outer metal layer.

Description

Technical Field

[0001] The present invention relates to the technical field of metal composite wires, and in particular to a method and device for manufacturing a double-layer metal composite wire. Background Art

[0002] Double-layer metal composite wires are composite wires whose core and outer layers consist of two different metals or alloys. They are widely used as leads for electronic components such as high-frequency cables, shielded cables, capacitors, transistors, and bonding wires. Conventional production involves first creating a dissimilar metal composite billet through solid-solid or solid-liquid composite methods, followed by multiple drawing and annealing steps to achieve the target wire diameter and performance. However, the dissimilar metals exhibit significant differences in mechanical properties such as tensile strength, elastic modulus, and elongation, leading to mismatched stress-strain responses. This is particularly true for double-layer metal composite wires with a strong outer layer and a soft core, such as copper-clad aluminum, steel-clad copper, Kovar-clad copper, gold-clad silver, and palladium-clad copper. This inconsistency in plastic deformation during the drawing process often leads to cracking of the composite metal and exposure of the core material, significantly impacting production efficiency and the final wire's electrical conductivity, thermal conductivity, strength, corrosion resistance, and other properties. Effective solutions to this problem are lacking in engineering production.

[0003] In view of this, the present invention is proposed. Summary of the Invention

[0004] The first object of the present invention is to provide a method for manufacturing a double-layer metal composite wire. During the composite wire drawing stage, a current-assisted method is used to match the deformation of the metal cladding layer with the core layer base metal, thereby suppressing cracking and wire breakage of the composite wire during the drawing process, improving production efficiency, reducing energy consumption, and extending the life of the drawing die.

[0005] A second object of the present invention is to provide a manufacturing device for a double-layer metal composite wire, which is suitable for the manufacturing method of the double-layer metal composite wire as described above.

[0006] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are adopted:

[0007] A method for manufacturing a double-layer metal composite wire comprises the following steps:

[0008] S1. Take a double-layer metal composite blank rod, the double-layer metal composite blank rod comprises a core metal wire and a metal cladding layer coated on the outer surface of the core metal wire, the tensile strength of the metal cladding layer is greater than the core metal wire;

[0009] S2. Drawing the bilayer metal composite blank rod in multiple passes until a composite metal wire having a target wire diameter is obtained, applying a pulsed current to the metal cladding layer within the drawing zone during the drawing process to match the mechanical properties of the metal cladding layer with those of the core metal wire and suppress interface fracture, wherein the frequency f of the pulsed current satisfies the first condition or the second condition;

[0010] The first condition is: σ1≤σ2;

[0011] The second condition is: σ1≥σ2;

[0012] Wherein, σ1 is the electrical conductivity of the core metal wire, σ2 is the electrical conductivity of the metal cladding layer, μ2 is the magnetic permeability of the metal cladding layer, and ω is the thickness of the metal cladding layer;

[0013] S3. Annealing the composite metal wire to obtain the double-layer metal composite wire.

[0014] Preferably, the double-layer metal composite billet is prepared by a core-filling continuous casting method.

[0015] Preferably, the initial diameter of the double-layer metal composite blank is 5-20 mm, and the initial thickness of the metal cladding layer is not less than 0.1 mm.

[0016] Preferably, the frequency f of the pulse current also satisfies:

[0017]

[0018] Among them, v1 is the drawing speed, l1 is the length of the compression zone of the drawing die, and l2 is the length of the sizing zone of the drawing die.

[0019] Preferably, the frequency f of the pulse current is 500 Hz-10000 kHz.

[0020] Preferably, the average current density J applied to the double-layer metal composite blank or the composite metal wire during any drawing process is 100-1000 A / mm 2 .

[0021] Preferably, the duty cycle of the pulse current is 5%-20%.

[0022] Preferably, the drawing is performed in a drawing liquid, which is an insulating medium.

[0023] Preferably, the surface reduction rate of the drawing process is 10%-15%, and the drawing speed is 8-50 m / min.

[0024] A manufacturing device for a double-layer metal composite wire, suitable for the manufacturing method of a double-layer metal composite wire described in any of the aforementioned embodiments, comprising an unwinding device, a winding device, a pulse power supply, and a drawing device and a current transfer device arranged between the unwinding device and the winding device, wherein the pulse power supply transfers current to the metal cladding in the drawing area through the current transfer device.

[0025] Preferably, the drawing device includes a drawing box and a drawing die, a cooling medium and two guide wheels located in the drawing box. The drawing die is immersed in the cooling medium. The two guide wheels are respectively located on both sides of the drawing die. The drawing box is also provided with a cooling medium inlet and a cooling medium outlet. The cooling medium is a drawing liquid, and a thermocouple is provided in the cooling medium.

[0026] Preferably, the current transfer device includes two brushes and two conductive guide wheels, the core of the conductive guide wheel is made of insulating material, and the outer surface is provided with a conductive layer. The two brushes and the two conductive guide wheels are respectively located on both sides of the drawing die, and the positive and negative output ends of the pulse power supply are respectively connected to the two brushes through wires, and the two brushes are respectively in contact with the conductive layers of the two conductive guide wheels.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] (1) During the wire drawing process, the present invention applies high-frequency and high-energy pulse current to the composite metal wire in the drawing zone, and utilizes the "skin effect" of alternating current to allow most of the current to pass through the metal cladding layer, thereby utilizing the "electroplasticity" effect to soften only the high-strength metal of the cladding layer, while the mechanical properties of the low-strength metal in the core remain basically unchanged, thereby matching the mechanical properties of the soft metal in the core, reducing the shear force between dissimilar metals, inhibiting interface fracture, avoiding cracking of the metal cladding layer and exposure of the core material, and improving the quality of the double-layer metal composite wire. At the same time, the softening of the surface metal can also extend the life of the wire drawing die, reduce the total drawing force, reduce wire breakage, and improve production efficiency and forming quality.

[0029] (2) The present invention takes into account the influence of the difference in electrical conductivity between the inner and outer metal layers on the skin effect. Regardless of whether the electrical conductivity of the core metal wire is greater than or less than the electrical conductivity of the metal cladding layer, the parameter setting in the method of the present invention can make the current mainly concentrated in the metal cladding layer, forming the basis for softening only the high-strength cladding metal. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0031] Figure 1 A cross-sectional view of a double-layer metal composite wire and a current density distribution diagram in the skin effect of a pulsed current provided by an embodiment of the present invention;

[0032] Figure 2 Schematic diagram of a double-layer metal composite wire manufacturing device provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0033] The technical scheme of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and specific embodiments, but it will be understood by those skilled in the art that the following described embodiments are part of embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention, and should not be considered as limiting the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of the present invention. Those who do not specify specific conditions in the embodiments are carried out according to normal conditions or the conditions recommended by the manufacturer. Those whose reagents or instruments are not specified by the manufacturer are conventional products that can be purchased commercially.

[0034] A first aspect of the present invention provides a method for manufacturing a double-layer metal composite wire, comprising the following steps:

[0035] S1 take double metal composite billet rod, double metal composite billet rod comprising a core metal wire and a metal cladding coated on the outer surface of the core metal wire, the tensile strength of the metal cladding layer is greater than the core metal wire;

[0036] S2. Drawing the double-layer metal composite blank rod in multiple passes until a composite metal wire having a target wire diameter is obtained, applying a pulsed current to the metal cladding layer within the drawing zone during the drawing process to match the mechanical properties of the metal cladding layer with those of the core metal wire and suppress interface fracture, wherein the frequency f of the pulsed current satisfies the first condition or the second condition;

[0037] The first condition is: σ1≤σ2;

[0038] The second condition is: σ1≥σ2;

[0039] Wherein, σ1 is the electrical conductivity of the core metal wire, the unit is S / m, σ2 is the electrical conductivity of the metal coating, the unit is S / m, μ2 is the magnetic permeability of the metal coating, the unit is H / m, ω is the thickness of the metal coating, the unit is m, and the unit of f is Hz;

[0040] S3. Annealing the composite metal wire having the target wire diameter obtained in step S2 to obtain a double-layer metal composite wire.

[0041] The present invention utilizes the skin effect and electroplasticity of high-frequency pulse current to allow most of the current density to pass through the cladding metal, softening the high-strength cladding metal, effectively reducing the shear force between the cladding metal and the core metal, matching the mechanical properties of the two, and inhibiting interface fracture. This avoids cracking of the metal cladding and exposure of the core material caused by large differences in mechanical properties such as tensile strength, elastic modulus, and elongation between the two metals and mismatched stress-strain responses during the drawing process, thereby improving the quality of the double-layer metal composite wire. At the same time, the softening of the high-strength metal cladding reduces the total drawing force, reduces wire breakage, improves production efficiency and forming quality, and extends the life of the wire drawing die.

[0042] The present invention also considers the influence of the relative conductivity of the core metal and the cladding metal on the skin effect. When the conductivity of the outer metal (metal cladding) is greater than or equal to the conductivity of the core metal wire (i.e., σ1≤σ2), the effective depth formula δ=(π·μ·f / ρ) -1 / 2 Control the frequency of the pulse current by controlling Where ω is the thickness of the coating layer, so that the skin penetration depth is less than or equal to the thickness of the coating metal, so that the current is mainly concentrated in the coating metal, achieving the effect of softening only the high-strength metal coating; However, the formula It is only applicable to the case where the electrical conductivity of the outer metal in the composite wire is ≥ the core metal, such as copper-clad aluminum. At this time, the current density is concentrated within the thickness ω of the metal cladding layer, and the current density in the core metal can be ignored; while for the case where the electrical conductivity of the outer metal is less than that of the core metal, such as steel-clad copper and Kovar alloy-clad copper, the current density in the core metal cannot be ignored. If the current density in the core metal is large, the core metal will also be softened, and it will be difficult to reduce or eliminate the difference in mechanical properties between the cladding metal and the core metal. The above formula is not applicable to the case where the electrical conductivity of the outer metal is less than that of the core metal (i.e., σ1>σ2); to address this problem, the present invention proposes a parameter setting method applicable to the case of σ1>σ2, that is, when σ1>σ2, the pulse frequency is controlled. When the formula takes the sign equal to ω, the maximum current density of the core metal (i.e., at the thickness of the metal coating ω) is 1 / e of the current density of the surface layer of the composite wire, the skin penetration depth is equal to the thickness of the metal coating, and the current mainly flows through the coating metal. When the formula takes the sign greater than ω, the skin penetration depth is less than the thickness of the metal coating, and as the depth increases, the current density continues to decrease exponentially. Therefore, under this condition, the current density of the core metal can be ignored, and most of the current passes through the metal coating, which becomes the basis for achieving only softening of the high-strength coating metal.

[0043] formula The derivation process is as follows: The AC current density distribution in the wire J = J0e -z / δ , where J0 is the current density on the wire surface, the current density decreases exponentially from the wire surface to the core, and z is the depth from the wire surface. δ is the skin depth, and the current density at z = δ is 1 / e of the surface current density; Figure 1 As shown, for a double-layer metal composite wire, the core metal is recorded as material 1, the radius is r1, the conductivity is σ1, and the skin depth is In the core material, the current density distribution (0≤r≤r1), r is the distance from the center line of the wire core, J 1,0 is the current density on the core metal surface (i.e., r1); the cladding metal is recorded as material 2, with radius r2, conductivity σ2, and skin depth In the coating material, the current density distribution (r1≤r≤r2), J 2,0 is the current density at the metal surface of the coating layer (i.e., at r2); at r1; According to the principle of electric field continuity, E1(r1)=E2(r1), where but but If the current density on the surface of the core metal is required to be less than or equal to 1 / e of the current density on the surface of the cladding metal, that is, It requires Where ω is the coating thickness (ω=r2-r1), (σ1≥σ2), when σ1=σ2, It is consistent with the skin effect formula of the same metal and is a special case of the derived formula.

[0044] control σ1≤σ2 or The purpose of σ1≥σ2 is to make the skin depth δ greater than 90% of the thickness of the metal cladding, so that the current can be concentrated in most of the thickness of the metal cladding to ensure the plastic deformation of the metal cladding. If the frequency is too large, firstly, the current is mainly concentrated in a very thin layer on the surface of the metal cladding, and the current does not flow through the entire metal cladding, which is not conducive to the plastic deformation of the entire metal cladding and it is difficult to match the mechanical properties of the metal cladding with those of the core metal wire. Secondly, the power supply requirements are also very high. Therefore, the frequency range needs to be reasonably controlled to match the mechanical properties of the metal cladding with those of the inner metal wire.

[0045] In some specific embodiments of the present invention, a bilayer metal composite billet is produced using a core-filling continuous casting method. The cladding metal and inner metal billets are placed in respective crucibles for the cladding and core metals, respectively. The composite billet is then metallurgically bonded using a composite crystallizer using the core-filling continuous casting method. The core-filling continuous casting method is particularly suitable for producing composite billets with a high-melting-point metal cladding a low-melting-point metal core. The composite billet produced using this method exhibits high bonding strength, with the bonding layer exhibiting greater strength than the core metal.

[0046] In some specific embodiments of the present invention, when a double-layer metal composite billet is prepared by a core-filling continuous casting method, the melting temperatures of the core layer metal and the cladding layer metal are 50-250°C higher than the melting points of the corresponding metals, respectively. For example, they can be any point value among 50°C, 100°C, 150°C, 200°C, and 250°C, or a range value consisting of any two point values; the casting speed is 30-300 mm / min, for example, they can be any point value among 30 mm / min, 60 mm / min, 100 mm / min, 150 mm / min, 200 mm / min, 250 mm / min, and 300 mm / min, or a range value consisting of any two point values.

[0047] In some specific embodiments of the present invention, the initial diameter of the double-layer metal composite blank is 5-20 mm, for example, it can be any point value among 5 mm, 8 mm, 10 mm, 12 mm, 15 mm, 18 mm, 20 mm, or a range value consisting of any two point values; the initial thickness of the metal coating layer is not less than 0.1 mm, for example, it can be 0.1 mm, 0.6 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 4 mm, 5 mm, 6 mm, etc.

[0048] In some specific embodiments of the present invention, the frequency f of the pulse current also satisfies:

[0049]

[0050] Among them, v1 is the drawing speed, the unit is m / s, l1 is the length of the compression zone of the drawing die, the unit is m, l2 is the length of the sizing zone of the drawing die, the unit is m, and the unit of f is Hz.

[0051] The present invention takes into account the influence of the drawing rate, and applies pulse current at least 60 times during the deformation of the wire through the drawing die, fully exerting the electroplastic effect of the current on the wire, ensuring that high-frequency pulse current passes through the wire during the plastic deformation stage, thereby ensuring the effect and consistency of the electroplasticity; the length l1 of the compression zone of the drawing die is usually not less than 100% of the die wire diameter D, and the length l2 of the sizing zone of the drawing die is usually 20%-50% of the die wire diameter D.

[0052] In some specific embodiments of the present invention, the frequency f of the pulse current is 500 Hz-10000 kHz, for example, it can be any point value among 1.4 kHz, 10 kHz, 21 kHz, 32.5 kHz, 50 kHz, 100 kHz, 520 kHz, 1000 kHz, 2100 kHz, 3100 kHz, 5500 kHz, 8000 kHz, 9740 kHz, and 10000 kHz, or a range value consisting of any two point values; adjustment within this frequency range can enable most of the current to pass through the metal coating, and only the outer high-strength metal coating is softened by electroplasticity, thereby matching the mechanical properties of the inner and outer metal layers.

[0053] In some specific embodiments of the present invention, the average current density J applied to the double-layer metal composite billet or the composite metal wire during any drawing process is 100-1000 A / mm 2 , for example, it can be 100A / mm 2 、300A / mm 2 , 500A / mm 2 , 700A / mm 2 , 900A / mm 2 , 1000A / mm 2 The range of values ​​composed of any point value or any two point values ​​in the equation is ; controlling the average current density within this range can ensure both the electroplastic effect and the safety of the work.

[0054] In some specific embodiments of the present invention, the duty cycle of the pulse current is 5%-20%, for example, it can be any value among 5%, 10%, 15%, 20%, or a range consisting of any two values.

[0055] In some specific embodiments of the present invention, the drawing process is carried out in a drawing liquid, which is an insulating medium. The drawing liquid acts as a lubricant on the one hand and a cooling medium on the other hand, cooling the metal wire in the energized area to ensure a smooth surface of the metal wire.

[0056] In some specific embodiments of the present invention, the area reduction rate of the drawing process is 10%-15%, and the drawing speed is 8-50 m / min.

[0057] In some specific embodiments of the present invention, the annealing temperature of the annealing process is based on the annealing temperature of the high melting point metal, usually 30%-40% of the melting point, and the annealing time is 1-5 minutes.

[0058] like Figure 2 As shown, the second aspect of the present invention provides a manufacturing device for a double-layer metal composite wire, which is suitable for the manufacturing method of the double-layer metal composite wire described in any one of the aforementioned embodiments, including an unwinding device, a winding device, a high-frequency pulse power supply, and a drawing device and a current transfer device arranged between the unwinding device and the winding device. The composite wire is supported and tensioned by the unwinding device and the winding device. The rotation of the unwinding device and the winding device can drive the composite wire to be continuously transmitted toward the winding device at a certain speed. The drawing device draws the composite wire, and the pulse power supply transfers current to the composite wire in the drawing area through the current transfer device. By utilizing the skin effect and electroplasticity, the current is mainly concentrated on the metal cladding, so that the high-strength metal cladding is softened, the shear force between the cladding metal and the core metal is reduced, the mechanical properties of the two are matched, the interface fracture is suppressed, thereby avoiding cracking of the metal cladding and exposure of the core material, and improving the quality of the double-layer metal composite wire. At the same time, the softening of the high-strength metal cladding reduces the total drawing force, reduces wire breakage, improves production efficiency and forming quality, and extends the life of the wire drawing die.

[0059] In some specific embodiments of the present invention, the drawing device includes a drawing box and a drawing die, a cooling medium and two guide wheels located in the drawing box. The drawing die is immersed in the forced circulation cooling medium. The two guide wheels are located on both sides of the drawing die and serve as a guide. The drawing box is also provided with a cooling medium inlet and a cooling medium outlet for the entry and exit of the cooling medium. The cooling medium is a drawing liquid, which is an insulating medium and serves as lubrication and cooling. A thermocouple is provided near the drawing die in the cooling medium to detect the temperature of the drawing liquid near the drawing die to avoid excessive temperature affecting the cooling effect.

[0060] In some specific embodiments of the present invention, the current transfer device includes two brushes and two conductive guide wheels. The conductive guide wheels are made of composite materials, the core is an insulating material, such as aluminum oxide, and the outer surface is provided with a conductive layer, such as a tungsten carbide coating. The two brushes and the two conductive guide wheels are respectively located on both sides of the drawing die. The positive and negative output ends of the pulse power supply are respectively connected to the two brushes through wires, and the two brushes are respectively in contact with the conductive layers of the two conductive guide wheels. The high-frequency pulses can be transmitted to the conductive guide wheels through the brushes, and then introduced into the composite wire.

[0061] The following describes some embodiments of the present invention in detail with reference to specific application examples. Unless otherwise specified, the raw materials used in the examples can be purchased from the market.

[0062] Example 1

[0063] Preparation of 304 stainless steel copper clad composite metal wire:

[0064] S1. 304 stainless steel and 99.99% high-purity copper billets were placed in cladding and core metal crucibles, respectively. A core-filling continuous casting method was used to achieve metallurgical bonding of the dissimilar metals in a composite crystallizer to produce a 10 mm diameter composite metal billet. The core copper metal had a diameter of 4 mm. The cladding steel and core copper were smelted at 1700°C and 1200°C, respectively, at a casting speed of 60 mm / min.

[0065] S2. Use a coarse wire drawing machine to draw the bimetallic composite billet to 2mm in a single die, with a surface reduction rate of 10%-12% per pass. The drawing speed v1 is 8-50m / min. The drawing die is required to be immersed in a forced circulating drawing liquid. A high-frequency pulse current is applied during the drawing process. The positive and negative output terminals of the power supply are connected to a conductive guide wheel through brushes. The guide wheel is made of a composite material with an aluminum oxide core and a conductive and wear-resistant tungsten carbide sprayed on the outer layer. The high-frequency pulse can be transmitted to the conductive guide wheel through the brush and then introduced into the composite wire. The average current density J = 320A / mm 2 , the frequency f is 510kHz-10000kHz, meeting the frequency application principle This principle requires that at least 60 pulse currents be applied during the deformation of the wire through the drawing die; l1 is the length of the compression zone of the drawing die, which is approximately 100% of the wire diameter of the die; l2 is the length of the sizing zone of the drawing die, which is approximately 20% of the wire diameter of the die. The values ​​of v1, l1 and l2 for different passes are shown in Table 1, and the duty cycle is 10%.

[0066] Since the conductivity of the core copper is greater than that of the outer 304 stainless steel, the frequency application principle is Here ω is the thickness of the coating metal, σ1 is the electrical conductivity of copper, which is 57.1×10 6 S / m, μ r1 is the relative magnetic permeability of copper, which is 0.99999H / m, and σ2 is the electrical conductivity of steel, which is 1.5×10 6 S / m, μ r2 is the relative magnetic permeability of steel, which is 1.005H / m, e is a natural constant, μ0=4π×10 -7H / m is the vacuum magnetic permeability. The thickness of the steel coating layer during the drawing process is 3mm-0.6mm. The pulse current frequency should be selected according to the different thicknesses of the steel coating layer during each drawing process. The pulse current frequencies applied during different drawing processes are shown in Table 1.

[0067] S3. The bimetallic composite wire after final drawing is annealed online at an annealing temperature of 600° C. for 5 minutes.

[0068] Table 1

[0069]

[0070] Example 2

[0071] Preparation of copper-clad aluminum composite metal wire:

[0072] S1. A 99.99% pure copper billet and a 99.99% pure aluminum billet were placed in a cladding and core metal crucible, respectively. A core-filling continuous casting method was used to achieve metallurgical bonding of the dissimilar metals in a composite crystallizer to produce a composite metal billet with a diameter of 8 mm. The core aluminum metal had a diameter of 4 mm. The cladding copper and the core aluminum were smelted at temperatures of 1200°C and 850°C, respectively, at a casting speed of 60 mm / min.

[0073] S2. Use a coarse wire drawing machine to draw the bimetallic composite billet in a single die and reduce its diameter to 2mm. The surface reduction rate is 10%-13%. The drawing speed v1 is 8-50m / min. The drawing die is required to be immersed in the forced circulation drawing liquid. High-frequency pulse current is applied during the drawing process. The positive and negative output terminals of the power supply are connected to the conductive guide wheel through brushes. The guide wheel is made of a composite material with an aluminum oxide core and a conductive and wear-resistant tungsten carbide sprayed on the outer layer. The high-frequency pulse can be transmitted to the conductive guide wheel through the brush and then introduced into the composite wire. The average current density J = 160A / mm 2 , the frequency f is 500Hz-100kHz, this frequency range can meet the frequency application principle Where l1 is the length of the compression zone of the drawing die, approximately 100% of the wire diameter; l2 is the length of the sizing zone of the drawing die, approximately 20% of the wire diameter. The values ​​of v1, l1, and l2 for different passes are shown in Table 2. This principle requires that at least 60 pulse currents be applied during the deformation of the wire through the drawing die; the duty cycle is 10%.

[0074] Since the conductivity of the core aluminum is less than that of the outer copper, the frequency application principle is Here ω is the thickness of the coating metal, σ1 is the electrical conductivity of aluminum, which is 37.7×10 6 S / m, μ r1is the relative magnetic permeability of aluminum, which is 1.0003H / m, and σ2 is the electrical conductivity of copper, which is 57.1×10 6 S / m, μ r2 is the relative magnetic permeability of copper, which is 0.99999H / m, e is a natural constant, μ0=4π×10 -7 H / m is the vacuum magnetic permeability. The thickness of the copper coating during the drawing process is 2.0mm-0.37mm. The pulse current frequency should be selected according to the different thicknesses of the copper coating during each drawing process. The pulse current frequencies applied during different drawing processes are shown in Table 2.

[0075] S3. The bimetallic composite wire after final drawing is annealed online at an annealing temperature of 580° C. for 1 minute.

[0076] Table 2

[0077]

[0078] Comparative Example 1

[0079] Comparative Example 1 is similar to Example 1, except that a 500 Hz medium frequency pulse current is used to assist the drawing, and the other conditions are the same as those of Example 1.

[0080] Comparative Example 2

[0081] Comparative Example 2 is similar to Example 1, except that pulse current is not used to assist drawing during the drawing process, and the other conditions are the same as Example 1.

[0082] Comparative Example 3

[0083] Comparative Example 3 is similar to Example 1, except that the frequency applied in each pass during the drawing process is based on the skin depth formula value, but much smaller than The remaining conditions are the same as in Example 1.

[0084] Comparative Example 4

[0085] Comparative Example 4 is similar to Example 2, except that the frequency applied in each pass during the drawing process is based on the skin depth formula Value, some passes do not meet The remaining conditions are the same as those in Example 2.

[0086] Test example

[0087] A sample was taken every 1 meter from the composite wire prepared in each embodiment and comparative example. Ten samples were taken for each composite wire. The density of the composite wire was tested by the Archimedes drainage method to check the density of the composite wire. The density is equal to the measured density / theoretical density. The theoretical density of the 304 steel-clad copper composite wire in Example 1 of the present invention and Comparative Examples 1, 2, and 3 is 8.0884 g / cm 3 The theoretical density of the copper-clad aluminum composite wire in Example 2 and Comparative Example 4 is 7.365 g / cm 3 The test results are shown in Table 3.

[0088] Table 3

[0089]

[0090]

[0091] As can be seen from the table, for the steel-clad copper composite wire, the average density of the composite wire prepared by the method of the present invention is 8.0878 g / cm 3 The highest density is 99.993%, indicating that the composite wire prepared by this method is dense, and there are very few voids or fracture defects at the steel-copper interface, reflecting the consistent deformation of dissimilar materials during the drawing process; the average density of the composite wire prepared by medium frequency 500Hz pulse current assisted drawing is 8.0582g / cm 3 The density is 99.627%, which is worse than that of the method of the present invention and better than that of the traditional direct drawing method, indicating that the pulse current also has a certain effect, but the effect is general; the composite linear density prepared by the traditional direct drawing method is 8.0386g / cm 3 , the lowest density is 99.384%, indicating that a large number of dissimilar interface fractures and delamination occurred during the drawing process; the average density of the composite wire prepared by pulse current assisted drawing according to the traditional skin depth principle is 8.0731g / cm 3 The density is 99.811%, which is higher than that of Comparative Example 1 and Comparative Example 2, but worse than that of the method of the present invention. It can be seen that the bimetallic composite wire prepared by the method of the present invention has the best quality.

[0092] For copper-clad aluminum wire, the average density of the composite wire prepared by the method of the present invention is 7.3645 g / cm 3 The density is 99.993%, indicating that there are very few holes or fracture defects at the copper-aluminum interface, reflecting the consistent deformation of dissimilar materials during the drawing process; the composite linear density prepared by the method that meets the skin depth frequency selection principle but does not meet the mold specification and drawing rate selection principle is 7.3608g / cm 3 The density is 99.943%, which is lower than that of the method of the present invention, indicating that some dissimilar interface fracture occurs during the drawing process. Therefore, it can be seen that the bimetallic composite wire prepared by the method of the present invention has the best quality.

[0093] Although the present invention has been illustrated and described using specific embodiments, it should be appreciated that the above embodiments are merely intended to illustrate the technical solutions of the present invention rather than to limit them. Those skilled in the art should understand that the technical solutions described in the above embodiments may be modified, or some or all of the technical features thereof may be replaced by equivalents, without departing from the spirit and scope of the present invention. However, these modifications or replacements do not deviate from the essence of the corresponding technical solutions within the scope of the technical solutions of the embodiments of the present invention. Therefore, this means that all such replacements and modifications within the scope of the present invention are included in the appended claims.

Claims

1. A method for manufacturing a double-layer metal composite wire, characterized in that: The following steps are involved: S1 take a double metal composite billet rod, the double metal composite billet rod comprises a core wire and a metal cladding coated on the outer surface of the core wire, the tensile strength of the metal cladding is greater than the core wire; S2. The double-layer metal composite blank is subjected to multiple drawing passes until a composite metal wire having a target wire diameter is obtained. During the drawing process, a pulse current is applied to the metal cladding layer in the drawing zone to match the mechanical properties of the metal cladding layer with the core metal wire to suppress interface fracture. The frequency of the pulse current is f Satisfy the first or second condition; The first condition is: , σ 1≤ σ 2; The second condition is: , σ 1≥ σ 2; Wherein, σ1 is the electrical conductivity of the core metal wire, the unit is S / m, σ2 is the electrical conductivity of the metal coating layer, the unit is S / m, µ 2 is the magnetic permeability of the metal coating layer, the unit is H / m, ω is the thickness of the metal coating layer, in m, f The unit is Hz; S3. Annealing the composite metal wire to obtain the double-layer metal composite wire.

2. The method for manufacturing a double-layer metal composite wire according to claim 1, wherein: The double-layer metal composite billet is prepared by a core-filling continuous casting method; And / or, the initial diameter of the double-layer metal composite blank is 5-20 mm, and the initial thickness of the metal coating layer is not less than 0.1 mm.

3. The method for manufacturing a double-layer metal composite wire according to claim 1, wherein: The frequency of the pulse current f Also meets: ； in, v 1 is the drawing speed, the unit is m / s, l 1 is the length of the compression zone of the drawing die, the unit is m, l 2 is the length of the sizing zone of the drawing die, in m. f The unit is Hz.

4. The method for manufacturing a double-layer metal composite wire according to claim 1, wherein: The frequency of the pulse current f 500Hz-10000kHz.

5. The method for manufacturing a double-layer metal composite wire according to claim 1, wherein: The average current density applied to the double-layer metal composite billet or the composite metal wire during any drawing process is J 100-1000A / mm 2 .

6. The method for manufacturing a double-layer metal composite wire according to claim 1, wherein: The duty cycle of the pulse current is 5%-20%.

7. The method for manufacturing a double-layer metal composite wire according to claim 1, wherein: The drawing is carried out in a drawing liquid, which is an insulating medium; And / or, the drawing process has a pass reduction rate of 10%-15%, and a drawing speed of 8-50 m / min.

8. A manufacturing device for a double-layer metal composite wire, characterized in that: A method for manufacturing a double-layer metal composite wire according to any one of claims 1 to 7, comprising an unwinding device, a winding device, a pulse power supply, and a drawing device and a current transfer device arranged between the unwinding device and the winding device, wherein the pulse power supply transfers current to the metal cladding in the drawing zone through the current transfer device.

9. The manufacturing device of the double-layer metal composite wire according to claim 8, characterized in that: The drawing device includes a drawing box and a drawing die, a cooling medium and two guide wheels located in the drawing box. The drawing die is immersed in the cooling medium. The two guide wheels are respectively located on both sides of the drawing die. The drawing box is also provided with a cooling medium inlet and a cooling medium outlet. The cooling medium is a drawing liquid, and a thermocouple is provided in the cooling medium.

10. The manufacturing device of the double-layer metal composite wire according to claim 9, characterized in that: The current transfer device includes two brushes and two conductive guide wheels. The core of the conductive guide wheel is made of insulating material and the outer surface is provided with a conductive layer. The two brushes and the two conductive guide wheels are respectively located on both sides of the drawing die. The positive and negative output ends of the pulse power supply are respectively connected to the two brushes through wires, and the two brushes are respectively in contact with the conductive layers of the two conductive guide wheels.

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