Joint between copper terminal and aluminum wire, and magnetic induction welding method therefor

Abstract

A joint of a copper terminal and an aluminum wire, the copper terminal is divided into a connecting part and a functional part connected to the connecting part, and an aluminum wire core of the aluminum wire is connected to the connecting part of the copper terminal. Preferably, the aluminum wire core extends or does not extend to the functional part. The connecting part is a component of the copper terminal that is connected with the aluminum wire, and the functional part is a fixed area of the copper terminal that is configured to connect to a power consumption device.

Claims

1. A joint of a copper terminal and an aluminum wire, wherein, the copper terminal is divided into a connecting part and a functional part connected to the connecting part, and an aluminum wire core of the aluminum wire is connected to the connecting part of the copper terminal; the aluminum wire core extends or does not extend to the functional part; the joint of the copper terminal and the aluminum wire has a welding zone, and an area of the welding zone is at east 1% of an area of an overlapping zone of the aluminum wire and the copper terminal; and a metal spacer layer is arranged between the aluminum wire core and the connecting part of the copper terminal, and a thickness of the metal spacer layer is 3 μm to 5000 μm in a radial direction of the aluminum wire core.

2. The joint of the copper terminal and the aluminum wire according to claim 1, wherein, the area of the welding zone is at least 10% of that the area of the overlapping zone of the aluminum wire and the copper terminal.

3. A magnetic induction welding method for preparing the joint of the copper terminal and the aluminum wire according to claim 2, comprising the following steps: S1: assembling the aluminum wire core and the connecting part of the copper terminal, wherein a distance between the aluminum wire core and the connecting part of the copper terminal is 0 to 10 mm; adding a metal spacer layer between the aluminum wire core and the connecting part of the copper terminal, wherein a thickness of the metal spacer layer is 3 μm to 5000 μm; and S2: welding the aluminum wire core and the connecting part of the copper terminal together by magnetic induction welding so that an outer surface of the aluminum wire core is connected to a surface of the connecting part of the copper terminal.

4. The magnetic induction welding method for preparing the joint of the copper terminal and the aluminum wire according to claim 3, wherein, the distance between the metal spacer layer and the connecting part of the copper terminal is 0 to 10 mm; and S2 further comprises the following steps: welding the aluminum wire core, the connecting part of the copper terminal and the metal spacer layer together by magnetic induction welding so that the outer surface of the aluminum wire core is connected to an inner surface of the metal spacer layer and an outer surface of the metal spacer layer is connected to the surface of the connecting part of the copper terminal.

5. The magnetic induction welding method for preparing the joint of the copper terminal and the aluminum wire according to claim 3, wherein, the method further comprises the following steps before S1: in a case that the aluminum wire core is a multi-strand aluminum wire core, the multi-strand aluminum wire core is formed by compacting.

6. The magnetic induction welding method for preparing the joint of the copper terminal and the aluminum wire according to claim 3, wherein the distance between the aluminum wire core and the connecting part of the copper terminal is 0 to 3 mm.

7. The magnetic induction welding method for preparing the joint of the copper terminal and the aluminum wire according to claim 3, wherein, the metal spacer layer is independently arranged; or the metal spacer layer is adhered to the copper terminal or the aluminum wire core by electroplating, pressure plating, chemical plating or arc spraying.

8. The joint of the copper terminal and the aluminum wire according to claim 1, wherein, the material of the metal spacer layer is one or any combination of nickel, cadmium, manganese, zirconium, cobalt, aluminum, tin, titanium, zinc, chromium, gold or silver.

9. The joint of the copper terminal and the aluminum wire according to claim 1, wherein the thickness of the metal spacer layer is 5 μm to 1000 pin.

10. The joint of the copper terminal and the aluminum wire according to claim 1, wherein, the metal spacer layer is independently arranged.

11. The joint of the copper terminal and the aluminum wire according to claim 1, wherein, the metal spacer layer is adhered to the copper terminal or the aluminum wire core by electroplating, pressure plating, chemical plating or arc spraying.

12. The joint of the copper terminal and the aluminum wire according to claim 1, wherein, the copper terminal is made of copper or copper alloy; and a shape of the connecting part is flat, arc-shaped, wing-shaped open, circular closed or polygonal closed.

13. The joint of the copper terminal and the aluminum wire according to claim 1, wherein, the aluminum wire is a solid aluminum wire or a multi-strand aluminum wire; and the aluminum wire core of the aluminum wire is made of aluminum or aluminum alloy.

14. A magnetic induction welding method for preparing the joint of the copper terminal and the aluminum wire according to claim 1, comprising the following steps: S1: assembling the aluminum wire core and the connecting part of the copper terminal, wherein a distance between the aluminum wire core and the connecting part of the copper terminal is 0 to 10 mm; adding a metal spacer layer between the aluminum wire core and the connecting part of the copper terminal, wherein a thickness of the metal spacer layer is 3 μm to 5000 μm; and S2: welding the aluminum wire core and the connecting part of the copper terminal together by magnetic induction welding so that an outer surface of the aluminum wire core is connected to a surface of the connecting part of the copper terminal.

15. The magnetic induction welding method for preparing the joint of the copper terminal and the aluminum wire according to claim 14, wherein, the distance between the metal spacer layer and the connecting part of the copper terminal is 0 to 10 mm; and S2 further comprises the following steps: welding the aluminum wire core, the connecting part of the copper terminal and the metal spacer layer together by magnetic induction welding so that the outer surface of the aluminum wire core is connected to an inner surface of the metal spacer layer and an outer surface of the metal spacer layer is connected to the surface of the connecting part of the copper terminal.

16. The magnetic induction welding method for preparing the joint of the copper terminal and the aluminum wire according to claim 14, wherein the distance between the aluminum wire core and the connecting part of the copper terminal is 0 to 3 mm.

17. The magnetic induction welding method for preparing the joint of the copper terminal and the aluminum wire according to claim 14, wherein, the metal spacer layer is independently arranged; or the metal spacer layer is adhered to the copper terminal or the aluminum wire core by electroplating, pressure plating, chemical plating or arc spraying.

18. The magnetic induction welding method for preparing the joint of the copper terminal and the aluminum wire according to claim 14, wherein, the method further comprises the following steps before S1: in a case that the aluminum wire core is a multi-strand aluminum wire core, the multi-strand aluminum wire core is formed by compacting.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic view showing the structure of a preferred embodiment of a joint of a copper terminal and an aluminum wire according to the present application.

(2) FIG. 2 is a schematic view showing the structure of another preferred embodiment of the joint of the copper terminal and the aluminum wire according to the present application.

(3) FIG. 3 is a schematic view showing the structure of the copper terminal according to the present application.

(4) FIG. 4 is a schematic view showing the structure of a cross section of a terminal at a certain stage in the process that the copper terminal as shown in FIG. 1 is welded with the wire core of a multi-strand aluminum wire by the magnetic induction welding.

(5) FIG. 5 is a schematic view showing the structure of the cross section of the terminal at the same stage as FIG. 4 by using a solid aluminum wire core.

(6) FIG. 6A and FIG. 6B are schematic views illustrating the distance between the copper terminal and the aluminum wire.

DETAILED DESCRIPTION OF EMBODIMENTS

(7) In order to further elaborate the technical means and functions adopted by the present application to achieve the intended object of the present application, the specific embodiments, structures, features and functions according to the present application are described in detail below with reference to the drawings and preferred embodiments.

First Embodiment

(8) This embodiment is one of the preferred embodiments of the joint of the copper terminal and the aluminum wire of the present application. As shown in FIG. 1, the copper terminal is divided into a connecting part 12 and a functional part 11 connected to the connecting part, and an aluminum wire core of the aluminum wire 21 is connected to the connecting part of the copper terminal. Preferably, the aluminum wire core extends or does not extend to the functional part.

(9) Preferably, the material of the copper terminal is copper or copper alloy. Preferably, the material of the aluminum wire core of the aluminum wire is aluminum or aluminum alloy.

(10) In this embodiment, the aluminum wire is a multi-core aluminum wire, and in other embodiments, the aluminum wire can also be a solid aluminum wire, as shown in FIG. 2.

(11) In one of the preferred embodiments, the shape of the connecting part is flat, arc-shaped, wing-shaped open, circular closed, or polygonal closed. In some specific installation layouts, copper terminals and aluminum wires are required to avoid interference positions, so the shape of the connecting part of the terminal is designed according to the special case of the cable installation, to facilitate the cable installation and avoid interference between the cable and other components.

(12) In one of the preferred embodiments, the joint of the copper terminal and the aluminum wire has a welding zone 13, and an area of the welding zone 13 is at least 1% of the area of the overlapping zone of the aluminum wire and the copper terminal. Preferably, the area of the welding zone 13 is at least 10% of the area of the overlapping zone of the aluminum wire and the copper terminal.

(13) In order to prove the beneficial effects of the above preferred embodiments, the inventor provides the following experiments: 120 sets of copper terminals and aluminum wires with the same material and structure are used, which are divided into 12 groups, that is, 10 sets for each group, the same magnetic induction welding machine and tooling, the same metal spacer Sn, and the same thickness of the metal spacer are used; and welding operations with the same area of the overlapping zone of the aluminum wire and the copper terminal and different areas of welding zone 13 are performed, to compare the effect of the different area proportions of the welding zone 13 in the overlapping zone of the aluminum wire and the copper terminal on the electrical and mechanical performances of the joint made by using magnetic induction welding.

(14) It can be seen from the data in Table 1 that the larger the area proportion of the welding zone 13 in the overlapping zone of the aluminum wire and the copper terminal, the better the voltage drop performance and pullout force performance of the corresponding welded joint, and when the proportion is less than 1%, the electrical and mechanical performances of the joint are apparently decreased. Therefore, the area of the welding zone 13 of the joint is at least 1% of the area of the overlapping zone of the aluminum wire and the copper terminal. Preferably, the area of the welding zone 13 of the joint is at least 10% of the area of the overlapping zone of the aluminum wire and the copper terminal.

(15) TABLE-US-00001 TABLE 1 Effect of different areas of welding zone on the voltage drop (mV) and the pullout force (N) Area Voltage pullout NO. proportion drop (mV) force(N) 1 100%  2.9 2189.7 2 90% 3.0 2057.6 3 80% 3.1 1998.5 4 70% 3.1 1973.6 5 60% 3.2 1936.8 6 50% 3.2 1922.1 7 40% 3.4 1900.5 8 30% 3.5 1873.7 9 20% 3.6 1862.3 10 10% 3.7 1830.6 11  1% 4.0 1822.5 12 <1% 4.2 1701.2

(16) In one of the preferred embodiments, a metal spacer layer is arranged between the aluminum wire core and the copper terminal.

(17) Preferably, the material of the metal spacer layer is one or any combination of nickel, cadmium, manganese, zirconium, cobalt, aluminum, tin, titanium, zinc and chromium. Preferably, the material of the metal spacer layer is one or any combination of tin, nickel or zinc. Preferably, the material of the metal spacer layer is one or a combination of gold or silver.

(18) Preferably, a thickness of the metal spacer layer is 3 μm to 5000 μm. Preferably, the thickness of the metal spacer layer is 5 μm to 1000 μm. In order to illustrate an implementation effect of the technical features, the inventor provides the corresponding data support, as shown in Table 2 and Table 3.

(19) TABLE-US-00002 TABLE 2 Effect of different thickness of the metal spacer layer on the pullout force (N) of the connecting part Thickness of the metal spacer layer 1 3 5 10 50 100 300 500 μm μm μm μm μm μm μm μm NO. The pullout force (N) after welding 1 1992 2172 2324 2481 2371 2318 2283 2234 2 1973 2164 2351 2517 2408 2324 2284 2218 3 1976 2181 2337 2493 2384 2331 2276 2221 4 1977 2165 2328 2534 2376 2317 2291 2235 5 1984 2164 2346 2513 2406 2321 2280 2216 6 1982 2169 2339 2529 2411 2319 2274 2213 7 1975 2165 2341 2492 2408 2318 2294 2224 8 1983 2160 2349 2537 2391 2324 2283 2230 9 1982 2171 2337 2528 2386 2320 2285 2219 10 1978 2173 2330 2483 2378 2315 2279 2228 Average 1980.2 2168.4 2338.2 2510.7 2391.9 2320.7 2282.9 2223.8 value Thickness of the metal spacer layer 800 1000 2000 3000 4000 5000 6000 μm μm μm μm μm μm μm NO. The pullout force (N) after welding 1 2201 2154 2094 2076 2055 2016 1975 2 2207 2150 2089 2068 2058 2014 1964 3 2202 2149 2088 2081 2059 2013 1968 4 2213 2158 2094 2074 2051 2019 1971 5 2205 2144 2091 2072 2057 2020 1972 6 2214 2146 2099 2076 2058 2017 1965 7 2198 2153 2086 2082 2049 2015 1969 8 2215 2161 2094 2068 2064 2021 1958 9 2209 2155 2097 2075 2056 2022 1967 10 2213 2158 2089 2070 2055 2018 1968 Average 2207.7 2152.8 2092.1 2074.2 2056.2 2017.5 1967.7 value

(20) TABLE-US-00003 TABLE 3 Effect of different thickness of the metal spacer layer on the voltage drop (mV) of the connecting part Thickness of the metal spacer layer 1 3 5 10 50 100 300 500 800 1000 2000 3000 4000 5000 6000 μm μm μm μm μm μm μm μm μm μm μm μm μm μm μm NO. The voltage drop (mV) after welding 1 4 3.5 3.3 3.1 3.2 3.4 3.6 3.6 3.7 3.8 4.1 4.1 4.2 4.2 5 2 4.3 3.6 3.3 3.1 3.2 3.4 3.5 3.7 3.5 4 4 4 4.2 4.4 5.1 3 4.1 3.4 3.2 3.1 3.3 3.4 3.6 3.6 3.6 3.9 4.1 4 4.1 4.2 5 4 4.3 3.5 3.1 3.3 3.2 3.5 3.6 3.7 3.7 4 3.8 4.2 4.3 4.3 5.2 5 4 3.4 3.3 3.1 3.3 3.5 3.5 3.5 3.8 3.9 4 4.2 4.3 4.4 5.1 6 4.1 3.4 3.3 3.2 3.1 3.5 3.5 3.6 3.8 3.8 3.8 4.2 4.2 4.3 5 7 4.1 3.4 3.2 3.1 3.3 3.4 3.5 3.7 3.6 3.8 3.9 4.1 4.1 4.3 5.1 8 4.3 3.5 3.3 3.2 3.2 3.4 3.4 3.7 3.8 4 4.1 4.3 4.1 4.3 5.2 9 4 3.4 3.2 3.2 3.3 3.5 3.6 3.6 3.6 3.8 4.1 4.1 4.2 4.4 5 Average 4.13 3.46 3.24 3.16 3.23 3.44 3.53 3.63 3.68 3.89 3.99 4.13 4.19 4.31 5.08 value

(21) It can be seen from the above table that when the thickness of the metal spacer layer is less than 3 μm or more than 5000 μm, the pullout force and voltage drop performance of the connecting part will be apparently decreased, so the thickness of the metal spacer layer is set as 3 μm to 5000 μm; and preferably, the thickness of the metal spacer layer is set as 5 μm to 1000 μm, and the welded joint has better performance.

(22) In order to realize the arrangement and function of the metal spacer layer, the metal spacer layer is independently provided; or, the metal spacer layer is attached to the copper terminal or aluminum wire core by electroplating, pressure plating, chemical plating or arc spraying.

Second Embodiment

(23) This embodiment is a preferred embodiment of the magnetic induction welding method for the copper terminal and the aluminum wire of the present application, which includes the following steps:

(24) S1: the aluminum wire core is assembled with the connecting part of the copper terminal, and the distance between the aluminum wire core and the connecting part of the copper terminal is 0 to 10 mm. Preferably, the distance between the aluminum wire core and the connecting part of the copper terminal is 0 to 3 mm.

(25) S2: the aluminum wire core and the connecting part of the copper terminal are welded together by magnetic induction welding, so that an outer surface of the aluminum wire core is connected with a surface of the connecting part of the copper terminal.

(26) Before step S1, an insulation layer of the aluminum wire is removed according to the size of the connecting part of the terminal, and then the portion of the aluminum wire with the insulation layer being peeled off and the connecting part of the copper terminal are assembled. FIG. 3 is a schematic view showing the structure of the copper terminal, and the copper terminal includes a functional part 11 and a connecting part 12 with an open structure. The connecting part is arranged to have an open structure, the processing is simple, and it is easier to use automatic equipment for production. Then, as shown in FIGS. 4 and 5, a welding end of the aluminum wire 21 after the insulation layer is peeled off is assembled with the connecting part 12 of the copper terminal, and the size of the removed insulation layer corresponds to the size of the connecting part of the copper terminal.

(27) The distance between the aluminum wire core of the aluminum wire and the connecting part of the copper terminal is 0 to 10 mm. Preferably, the distance between the welding end of the aluminum wire and the connecting part of the copper terminal is 0 to 3 mm.

(28) Next, the aluminum wire with the insulation layer being removed and the copper terminal are put into a work fixture, and a start button of the magnetic induction welding equipment is pressed to charge a capacitor by a charging power supply. After the set capacity of electricity is charged, the high voltage capacitance is discharged instantly, and the high voltage current passes through a magnetic induction coil to generate a high voltage electromagnetic field in the processing area, so that, under the action of Lorentz force, the conductive metals in the electromagnetic field collide with each other at a speed of 300-700 m/s in a duration of 30-100 μs, and fusion occurs at an atomic energy level, thereby realizing the connection between the terminal and the aluminum wire.

(29) The inventor has carried out many experiments on the impacts of the distance between the aluminum wire core of the aluminum wire and the connecting part of the copper terminal on the welding effect in the welding process, and found that the different distances mentioned above can have different impacts on the welding effect. The specific experimental data are as follows:

(30) TABLE-US-00004 TABLE 4 Impacts of different distances between the aluminum wire core of the aluminum wire and the connecting part of the copper terminal on the pullout force and the voltage drop of the connecting part NO. Distance (mm) pullout force (N) Voltage drop (mV) 1 0 2027.2 2.8 2 0.5 2351.4 2.8 3 1 2324.8 2.8 4 1.5 2331.5 2.8 5 2 2346.7 2.9 6 2.5 2338.6 2.9 7 3 2308.4 3.0 8 3.5 2215.8 3.6 9 4 2174.7 3.8 10 4.5 2108.6 3.9 11 5 2002.7 4.0 12 5.5 1942.8 4.2 13 6 1927.4 4.5 14 6.5 1903.4 4.6 15 7 1857.4 4.7 16 7.5 1804.6 4.9 17 8 1778.4 5.1 18 8.5 1739.7 5.1 19 9 1718.4 5.2 20 9.5 1678.3 5.3 21 10 1644.2 5.4 22 11 1581.9 6.3 23 12 1532.7 6.4

(31) It can be seen from the above table that the inventor found that when the distance between the welding end of the aluminum wire and the connecting part of the copper terminal is 0-10 mm, the pullout force is relatively high and the voltage drop is relatively low, and the welding effect meets the requirements of the mechanical and electrical performances of the joint of the copper terminal and the aluminum wire.

(32) Further, when the distance between the welding end of the aluminum wire and the connecting part of the copper terminal is 0-3 mm, the performance of the pullout force and voltage drop is better, and the welding effect is better.

(33) For the distances mentioned above, when the connecting part of the copper terminal is non-flat shaped, there may be multiple distance values, all of which are equal or not all equal. The two cases are further described and explained below. As shown in FIG. 6a, in a case that the aluminum wire is within the connecting part of the copper terminal and the distances between the welded surfaces are equal, that is, a=b=1 mm; at this time, if a is within the above range of 0-10 mm, it is within the scope of protection of the present application; as shown in FIG. 6b, in a case that the aluminum wire is within the connecting part of the copper terminal and the distances between the welded surfaces are not all equal, for example, in a case of a≠b≠c; at this time, a=1 mm, b=4 mm, c=12 mm, and if the minimum value of a, b and c is within the above range of 0-10 mm, it is within the scope of protection of the present application.

(34) In one of the embodiments, the aluminum wire core 21 is a multi-strand aluminum wire core. The function of this kind of multi-strand aluminum wire core is to utilize each strand in the multi-strand aluminum wire core to disperse a stress caused by the vibration in the vibration environment, so as to prolong the service life of the aluminum wire in the vibration environment.

(35) Preferably, the method further includes the following steps before Step S1: when the aluminum wire core is a multi-strand aluminum wire core, the multi-strand aluminum wire core is formed by extrusion.

(36) It should be noted that the use of this multi-strand aluminum wire core has its own structural defect, that is, there will be gaps inside the multi-strand aluminum wire core, and these gaps may cause residual water and air inside the multi-strand aluminum wire core. In order to solve this problem, a process is added before Step S1 by the inventor, that is, the multi-strand aluminum wire core is formed by extrusion first, so that there will be no gap inside the aluminum wire, thus excluding the entry of water and air, and avoiding the electrochemical reaction between copper and aluminum due to the water and air which may result in corrosion between the copper terminal and the aluminum wire and reduce the service life.

(37) Another beneficial effect of the extrusion process is that during the extrusion process, an oxide layer on the surface of the aluminum wire may be destroyed at the same time, which makes the electrical conductivity of the aluminum wire better, and make the welding effect more desirable.

(38) In another preferred embodiment, the aluminum wire core 21 can also be solid, In a non-vibration environment, a solid aluminum wire can be used, the processing cost of the solid aluminum wire is much less than that of the multi-strand aluminum wire, and the solid aluminum wire can be welded directly with the connecting part of the copper terminal, which can avoid an unqualified situation that some core wires of the multi-strand aluminum wire core are not welded. In addition, the interior is a solid aluminum wire, and it does not have an issue that there is an oxide film on the surface of the monofilament of the multi-strand aluminum wire core, and thus the electrical conductivity is better.

Third Embodiment

(39) This embodiment is another preferred embodiment of the magnetic induction welding method for the copper terminal and the aluminum wire of the present application and the joint structure formed thereby, and the difference between this embodiment and the above embodiment is as follows:

(40) In this embodiment, Step S1 further includes the following steps: a metal spacer layer is added between the welding end of the aluminum wire and the connecting part of the copper terminal. Since copper and aluminum are different elements, metal inertia of copper is greater than that of aluminum, and the electrode potential of copper and aluminum is quite different (copper is +0.337, aluminum is −1.662), when the two metals are in direct contact, aluminum will gradually lose electrons under the action of air and water, forming electrochemical reactions and resulting in corrosion of the aluminum wire and reducing the service life of wire hardness, and in severe cases, sparks generated at the wire harness joint due to poor contact may cause an accident (such as burning a car). However, the smaller the electrode potential difference between the metals is, the less apparent the electrochemical reaction is. Therefore, in the technical solution, the inventor introduces a solution providing the metal spacer layer, that is, a metal spacer layer is added between the aluminum wire core and the connecting part of the copper terminal, and the electrode potential of the material of the metal spacer layer is between copper and aluminum. After welding, the electrochemical reaction between the copper terminal and the aluminum wire will be reduced, thus prolonging the service life of wire harness and reducing the occurrence of accidents (such as burning a car).

(41) The material of the metal spacer layer is one or any combination of nickel, cadmium, manganese, zirconium, aluminum, tin, titanium, zinc, cobalt and chromium.

(42) Preferably, the material of the metal spacer layer is one or any combination of tin, nickel or zinc.

(43) The electrode potential of nickel is −0.250, the electrode potential of tin is −0.136, and the electrode potential of zinc is −0.763, which are between copper and aluminum. Moreover, nickel, tin and zinc are relatively easy to obtain and thus can be widely used in industrial production.

(44) Preferably, the material of the metal spacer layer may also be one or a combination of gold or silver. Gold and silver are very stable in chemical performance and have good electrical conductivity, and thus can also be used as the metal spacer layer.

(45) The shape of the metal spacer layer is sheet-shaped, arc-shaped, annular, wing-shaped or polygonal.

(46) The metal spacer layer can be independently arranged, or can be attached to the copper terminal or the wire core of the aluminum wire by electroplating, pressure plating, chemical plating or arc spray plating.

(47) As mentioned above, the metal spacer layer can be attached to the copper terminal or the aluminum wire core by electroplating, pressure plating, chemical plating or arc spraying, the specific methods are described as follows:

(48) The electroplating method includes the following steps: 1. placing the plating metal at an anode; 2. placing the material to be plated at a cathode; 3. connecting the cathode and anode by an electrolyte solution composed of positive ions of the plating metal; 4. using the power supply to provide direct current, to oxidize the metal at the anode (losing electrons), and allowing the positive ions in the solution to be reduced into atoms at the cathode (obtaining electrons) and to be accumulated on the surface layer of the cathode.

(49) The pressing plating method includes the following steps: 1. stacking two kinds of metals to be pressure welded; 2. applying a pressure force to make the surface to be welded fully diffused to realize the interatomic combination; 3. increasing the temperature according to different metals and pressure sources, to improve the welding effect and shortening the welding time.

(50) The chemical plating method is a plating method in which the metal ions in the plating solution are reduced into metal and deposited on a surface of a part with the help of a suitable reducing agent without external current.

(51) The arc spraying method includes transporting the metal spacer to an arc area and atomized, and spraying the atomized metal onto the surface of the workpiece at a high speed under the action of compressed gas, to form an arc spray coating.

(52) In order to prove the beneficial effect of the metal spacer layer on magnetic induction welding, the inventor made a copper terminal welding piece with plating protection and a copper terminal welding piece without plating protection to compare the mechanical and electrical performances of the two samples; and after 48 hours of salt spray experiment, the mechanical and electrical performances of the samples were also compared.

(53) TABLE-US-00005 TABLE 5 Effect of Ni plating on the performance of the welded connecting part before and after salt spray corrosion Without Ni plating layer With Ni plating layer Without Ni plating layer With Ni plating layer Before salt spray corrosion After 48 hours of salt spray corrosion pullout Voltage pullout Voltage pullout Voltage pullout Voltage No. force (N) drop(mV) force (N) drop(mV) force (N) drop(mV) force (N) drop(mV) 1 2216 3.2 2385 3.1 1865 4.8 2247 3.4 2 2184 3.4 2354 2.8 1923 4.7 2264 3.3 3 2264 3.1 2423 2.9 1884 4.8 2185 3.5 4 2310 3.5 2371 2.7 1867 4.6 2274 3.5 5 2275 3.4 2425 3.2 1928 4.5 2294 3.4 6 2245 3.2 2328 3.1 1924 4.8 2156 3.2 7 2268 3.3 2481 3 1874 4.7 2147 3.5 8 2289 3.5 2466 2.8 1850 4.5 2189 3.3 9 2327 3.1 2451 2.9 1867 4.6 2248 3.4 10 2254 3.5 2361 3.1 1902 4.9 2234 3.2 Average 2263.2 3.32 2404.5 2.96 1888.4 4.69 2223.8 3.37 value

(54) It can be seen from the above table that, the inventor found that after the Ni layer is plated on the copper terminal, the pullout force is increased and the voltage drop is decreased, that is, the mechanical and electrical performances of the copper terminal with the Ni layer after welding are better than those of the copper terminal without the Ni layer.

(55) Furthermore, the copper terminal is plated with the Ni layer, and after 48 hours of salt spray corrosion, the reduction of the performances of the pullout force and the voltage drop is apparently less than that of the joint without the Ni layer. In other words, the existence of the metal spacer is more beneficial for the manufacture of the joint of the copper terminal and aluminum wire by using magnetic induction welding, which can improve the mechanical and electrical performances of the joint of the copper terminal and the aluminum wire. The metal spacer layer is added between the aluminum wire core and the connecting part of the copper terminal. Preferably, the distance between the metal spacer layer and the connecting part of the copper terminal is 0 to 10 mm. Preferably, the distance between the metal spacer layer and the connecting part of the copper terminal is 0 to 3 mm. The following experiments are used to prove the effectiveness of the technical solution.

(56) TABLE-US-00006 TABLE 6 Effect of the distance between the metal spacer layer and the connecting part of the copper terminal on the performance of the welded connecting part NO. Distance (mm) pullout force (N) Voltage drop (mV) 1 0 2289.4 2.8 2 0.5 2317.4 2.9 3 1 2327.6 3.0 4 1.5 2344.8 3.0 5 2 2372.7 3.1 6 2.5 2366.8 3.2 7 3 2316.7 3.2 8 3.5 2213.3 3.6 9 4 2188.7 3.7 10 4.5 2149.4 3.8 11 5 2137.6 4.0 12 5.5 2086.4 4.2 13 6 2019.5 4.3 14 6.5 1983.8 4.4 15 7 1924.6 4.5 16 7.5 1873.5 4.6 17 8 1811.9 4.7 18 8.5 1792.7 4.9 19 9 1752.9 5.0 20 9.5 1722.8 5.1 21 10 1691.7 5.2 22 11 1592.1 6.3 23 12 1557.6 6.5

(57) It can be seen from the above table that, the inventor found that when the distance between the metal spacer layer and the connecting part of the copper terminal is 0 to 10 mm, the pullout force is relatively high, the voltage drop is relatively low, and the welding effect meets the requirements of the mechanical and electrical performances. When the distance between the metal spacer layer and the connecting part of the copper terminal is 0 to 3 mm, the above effect is more significant as shown in the table.

(58) It is should be noted that the content required to be considered by the distance mentioned in the above paragraph can be referred to the above description of the summary of the present application, the second embodiment and FIGS. 6A and 6b, and are not repeated herein.

(59) The remaining embodiments are the same as the above embodiments and are not repeated herein.

(60) The above embodiments are only preferred embodiments of the present application, and cannot be used to limit the scope of protection of the present application, and any non-substantive changes and substitutes made by those skilled in the art based on the present application fall within the scope of protection of the present application.