Manufacturing method and device of double-layer metal composite wire

Abstract

The invention relates to the technical field of metal composite wires, in particular to a manufacturing method and device of a double-layer metal composite wire. The manufacturing method comprises the following steps that S1, a double-layer metal composite blank rod is taken, the double-layer metal composite blank rod comprises a core layer metal wire and a metal coating layer coating the outer side of the core layer metal wire, and the tensile strength of the metal coating layer is larger than that of the core layer metal wire; s2, the double-layer metal composite blank rod is subjected to multi-pass drawing, a composite metal wire is obtained, pulse current is applied to a metal coating layer located in a drawing area in the drawing process, the mechanical property of the metal coating layer is made to be matched with that of a core layer metal wire, and interface fracture is restrained; and S3, the composite metal wire is subjected to annealing treatment, and the composite metal wire is obtained. According to the method, the effect that only the metal coating layer is softened is achieved by controlling pulse current parameters and utilizing the skin effect and the electroplastic performance, the drawing deformation of the inner metal and the drawing deformation of the outer metal are consistent, the quality of the composite wire is improved, and the method is suitable for the situation that the conductivity of the inner-layer metal is larger than that of the outer-layer metal.

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 wire is a composite wire product composed of two different metals or alloys in the core and outer layer. It is widely used as the lead wire of electronic parts such as high-frequency cables, shielding wires, capacitors, transistors, bonding wires, etc. Its conventional production method is to first make a dissimilar metal composite blank rod by solid-solid phase composite or solid-liquid phase composite method, and then perform multiple drawing and annealing to achieve the target wire diameter and target performance. However, the mechanical properties of dissimilar metals such as tensile strength, elastic modulus, and elongation are very different, and the stress-strain response is not matched. Especially for double-layer metal composite wires with strong outer and soft core, the plastic deformation of dissimilar metals is inconsistent during the drawing process, such as copper-clad aluminum, steel-clad copper, kovar alloy-clad copper, gold-clad silver, palladium-clad copper, etc., which often leads to cracking of the composite metal and exposure of the core material, which greatly affects the production efficiency and the conductivity, thermal conductivity, strength, corrosion resistance and other properties of the final wire. There is a lack of effective means to deal with this problem 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, in which a current-assisted method is used in the composite wire drawing stage to match the deformation of the metal coating 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 for 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 particularly 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, wherein 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, wherein the tensile strength of the metal cladding layer is greater than that of the core metal wire;

[0009] S2. Drawing the double-layer metal composite blank rod for multiple times until a composite metal wire with a target wire diameter is obtained, and 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 those of the core metal wire, thereby suppressing interface fracture, and the frequency f of the pulse 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 coating layer, μ2 is the magnetic permeability of the metal coating layer, and ω is the thickness of the metal coating layer;

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

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

[0015] Preferably, the initial diameter of the double-layer metal composite blank rod is 5-20 mm, and the initial thickness of the metal coating 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 in any drawing process is 100-1000A / mm 2 .

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

[0022] Preferably, the drawing is performed in a wire drawing liquid, and the wire drawing liquid 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 the double-layer metal composite wire described in any one of the aforementioned embodiments, comprises 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, and 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 wheels 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 wire 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 make most of the current pass through the metal coating, thereby utilizing the "electroplasticity" effect to soften only the high-strength metal of the coating, 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 coating 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 layers of metal 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, which becomes the basis for softening only the high-strength cladding layer metal. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying 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 pulse current provided by an embodiment of the present invention;

[0032] Figure 2 A 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. If specific conditions are not specified in the embodiments, they are carried out according to normal conditions or conditions recommended by the manufacturer. If the manufacturer is not specified in the reagents or instruments used, they are all 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 a double-layer metal composite billet rod, the double-layer metal composite billet rod comprises a core metal wire and a metal coating layer coated on the outer surface of the core metal wire, the tensile strength of the metal coating layer is greater than the core metal wire;

[0036] S2. Drawing the double-layer metal composite blank rod for multiple passes until a composite metal wire with a target wire diameter is obtained, and 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 those of the core metal wire, inhibit interface fracture, and the frequency f of the pulse current satisfies the first condition or the second condition;

[0037] The first condition is: σ1≤σ2;

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

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

[0040] S3. Annealing the composite metal wire with 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 so that most of the current density passes through the cladding metal, softens the high-strength cladding metal, effectively reduces the shear force between the cladding metal and the core metal, matches the mechanical properties of the two, and inhibits interface fracture, thereby avoiding 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 size of the conductivity of the core metal and the coating metal on the skin effect. When the conductivity of the outer metal (metal coating) is ≥ 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 coating thickness, 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; but the formula It is only applicable to the case where the 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 coating layer, and the current density in the core metal can be ignored; while for the case where the 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 is difficult to reduce or eliminate the difference in mechanical properties between the coating metal and the core metal. The above formula is not applicable to the case where the conductivity of the outer metal is less than that of the core metal (i.e., σ1>σ2); in response to 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 is equal, 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 on the surface 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 is greater than , 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 alternating 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., at 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 Then require Where ω is the coating thickness (ω=r2-r1), (σ1≥σ2), when σ1=σ2, It is consistent with the skin effect formula for 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 layer, so that the current can be concentrated in most of the thickness of the metal cladding layer to ensure the plastic deformation of the metal cladding layer. If the frequency is too large, firstly, the current is mainly concentrated in a very thin layer on the surface of the metal cladding layer, and the current does not pass through the entire metal cladding layer, which is not conducive to the plastic deformation of the entire metal cladding layer and it is difficult to match the mechanical properties of the metal cladding layer with the core metal wire; secondly, the power supply requirements are also very high, so it is necessary to reasonably control the frequency range to match the mechanical properties of the metal cladding layer with the inner metal wire.

[0045] In some specific embodiments of the present invention, the double-layer metal composite billet rod is prepared by core-filling continuous casting. The coating layer metal and the inner layer metal billet are placed in the coating layer and the core metal crucible respectively, and the composite metal billet rod is prepared by core-filling continuous casting through a composite crystallizer to achieve metallurgical bonding of dissimilar metals. The core-filling continuous casting method is particularly suitable for preparing a composite billet rod with a high-melting-point metal coating and a low-melting-point metal core. The composite billet rod prepared by this method has high bonding strength, and the bonding layer strength is higher than that of 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 respectively 50-250°C higher than the melting points of the corresponding metals, 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 30-300mm / min, for example, they can be any point value among 30mm / min, 60mm / min, 100mm / min, 150mm / min, 200mm / min, 250mm / min, and 300mm / 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 rod 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, and 20 mm, or a range value composed 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, applies pulse current at least 60 times during the deformation of the wire through the wire drawing die, and fully exerts the electroplastic effect of the current on the wire, which can ensure that the 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 wire drawing die is usually not less than 100% of the wire diameter D of the die, and the length l2 of the sizing zone of the wire drawing die is usually 20%-50% of the wire diameter D of the die.

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

[0053] In some specific embodiments of the present invention, the average current density J applied to the double-layer metal composite blank rod or the composite metal wire in any drawing process is 100-1000A / 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 value composed of any point value or any two point values ​​in the equation; 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 point value among 5%, 10%, 15%, 20% or a range value consisting of any two point values.

[0055] In some specific embodiments of the present invention, the drawing process is carried out in a wire drawing liquid, which is an insulating medium. The wire drawing liquid acts as a lubricant on the one hand and a cooling medium on the other hand to cool 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 surface 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, and includes 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 the current to the composite wire in the drawing area through the current transfer device. The skin effect and electroplasticity are used to make the current mainly concentrated on the metal coating layer, so that the high-strength metal coating layer is softened, and the shear force between the coating layer metal and the core metal is reduced, so that the mechanical properties of the two are matched, and the interface fracture is suppressed, thereby avoiding the cracking of the metal coating layer and the 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 coating layer 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 circulating cooling medium. The two guide wheels are respectively located on both sides of the drawing die to play a guiding role. 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 required to be an insulating medium and functions 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 tungsten carbide coating. The two brushes and the two conductive guide wheels are respectively located on both sides of the wire 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. High-frequency pulses can be transmitted to the conductive guide wheels through the brushes, and then introduced into the composite wire.

[0061] The following is a detailed description of some embodiments of the present invention in conjunction with specific application examples. The raw materials used in the examples can be purchased from the market unless otherwise specified.

[0062] Example 1

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

[0064] S1. 304 stainless steel and high-purity copper billets with a purity of 99.99% are placed in the cladding layer and the core metal crucible respectively, and the composite crystallizer is used to realize the metallurgical bonding of dissimilar metals by core-filling continuous casting to form a composite metal billet rod with a diameter of 10 mm, wherein the core copper metal diameter is 4 mm, the cladding layer steel is smelted at 1700°C, the core copper is smelted at 1200°C, and the casting speed is 60 mm / min;

[0065] S2. Use a rough wire drawing machine to draw the bimetallic composite billet rod in a single-mode to reduce the diameter to 2mm, the surface reduction rate is 10%-12%, the wire drawing speed v1 is 8-50m / min, the wire drawing die is required to be immersed in the forced circulation wire drawing liquid, and a high-frequency pulse current is applied during the drawing process. The positive and negative output ends of the power supply are connected to the conductive guide wheel through brushes. The guide wheel is made of composite material, the core is aluminum oxide, and the outer layer is sprayed with conductive and wear-resistant tungsten carbide material. The high-frequency pulse can be transmitted to the conductive guide wheel through the brush, and then introduced into the composite wire. Average current density J = 320A / mm 2 , the frequency f is 510kHz-10000kHz, meeting the frequency application principle This principle requires that pulse current be applied at least 60 times 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 metal thickness of the coating layer, 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, the annealing temperature is 600°C, and the annealing time is 5 minutes.

[0068] Table 1

[0069]

[0070] Example 2

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

[0072] S1. A high-purity copper billet with a purity of 99.99% and a high-purity aluminum with a purity of 99.99% are placed in a cladding layer and a core metal crucible respectively, and a composite metal billet rod with a diameter of 8 mm is made by a core-filling continuous casting method through a composite crystallizer to achieve metallurgical bonding of dissimilar metals, wherein the diameter of the core aluminum metal is 4 mm, the melting temperature of the cladding layer copper is 1200°C, the melting temperature of the core aluminum is 850°C, and the casting speed is 60 mm / min;

[0073] S2. Use a rough wire drawing machine to draw the bimetallic composite billet rod in a single-mode to reduce the diameter to 2mm, the surface reduction rate is 10%-13%, the wire drawing speed v1 is 8-50m / min, the wire drawing die is required to be immersed in the forced circulation wire drawing liquid, and a high-frequency pulse current is applied during the drawing process. The positive and negative output ends of the power supply are connected to the conductive guide wheel through brushes. The guide wheel is made of composite material, the core is aluminum oxide, and the outer layer is sprayed with conductive and wear-resistant tungsten carbide material. The high-frequency pulse can be transmitted to the conductive guide wheel through the brush, and then introduced into the composite wire. 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 wire drawing die, which is about 100% of the wire diameter of the die; l2 is the length of the sizing zone of the wire drawing die, which is about 20% of the wire diameter of the die. The values ​​of v1, l1 and l2 of 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 wire drawing die; the duty cycle is 10%.

[0074] Since the conductivity of the core aluminum is lower than that of the outer copper, the frequency application principle is Here ω is the metal thickness of the coating layer, 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 is annealed online after final drawing, with an annealing temperature of 580°C and an annealing time of 1 min.

[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 pulling, and the other conditions are the same as 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, and 10 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 was 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 was 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] It can be seen from the table that 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 density is the highest, which 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, but 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 line 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 heterogeneous 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, and is 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 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 worse than that of the method of the present invention, indicating that a certain amount of heterogeneous interface fracture occurs during the drawing process. 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 with specific embodiments, it should be appreciated that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. 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 make the essence of the corresponding technical solutions deviate from 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-layer metal composite blank rod, wherein 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, wherein the tensile strength of the metal cladding layer is greater than that of the core metal wire; S2. Drawing the double-layer metal composite blank rod for multiple times until a composite metal wire with a target wire diameter is obtained, and 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 those of the core metal wire, thereby suppressing interface fracture, and the frequency f of the pulse current satisfies the first condition or the second condition; The first condition is: The second condition is: Wherein, σ1 is the electrical conductivity of the core metal wire, σ2 is the electrical conductivity of the metal coating layer, μ2 is the magnetic permeability of the metal coating layer, and ω is the thickness of the metal coating layer; 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, characterized in that: The double-layer metal composite billet rod is prepared by core-filling continuous casting; And / or, the initial diameter of the double-layer metal composite blank rod 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, characterized in that: The frequency f of the pulse current also satisfies: 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.

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

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

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