Connecting member for aluminum electric wires and method for manufacturing the same

Abstract

This invention provides a highly reliable wire connector that can safely connect aluminum wires to copper wires and copper terminals, and can be manufactured at low cost. [Solution] A wire connecting member (1) characterized by comprising: a first conductive part (10) made of aluminum with a purity of 99.9% or more and having a first cylindrical part (11) into which an aluminum wire is inserted; a second conductive part (20) located adjacent to the first conductive part and made of copper or a copper alloy, having a second cylindrical part into which a copper wire is inserted or a terminal for connecting to equipment; and an atomic bonding part (30) formed at the interface between the first conductive part and the second conductive part by cold pressure welding at room temperature.

Description

[Technical Field]

[0001] The present invention relates to a connecting member for aluminum wires and a method for manufacturing the same, which is used to connect an aluminum wire or an aluminum alloy wire to an aluminum wire or terminal made of copper or a copper alloy. [Background technology]

[0002] Electricity has become an indispensable part of daily life, and there are a vast number of power transmission lines (electricity circuits) around the world. Electricity generated at power plants is transported to individual homes via substations, indoor transformers, and other facilities, and power lines are used to transmit power between these locations. Power lines are also used to supply power to various parts of electrical appliances and electric vehicles.

[0003] Copper is widely used for electrical wires and connecting components used to connect wires to other wires or equipment. Related technologies, such as those specified in JIS standards, have already been standardized for copper wires and connecting components. Electrical circuits using copper wires and copper connecting components are connected by inserting the copper wire into the copper connecting component and then mechanically joining them at room temperature using pressure welding or crimping. Pressure welding refers to joining objects by applying pressure to bring them into contact. Crimping refers to joining objects by applying pressure to plastically deform one or both of them. In both of these mechanical joining methods, it is necessary to enclose the outer circumference of the wire with a cylindrical or similar terminal and apply a mechanical load to the joint. If the terminal is too thin, a phenomenon occurs in heat cycle tests where loosening increases contact resistance. These mechanical joining methods, such as bonding and crimping, are also called riveting.

[0004] In recent years, the price of copper has risen, creating a demand for alternative materials. Against this backdrop, attempts have been made to replace copper wire with aluminum wire, and a technology has been developed to insert aluminum wire into aluminum connectors and crimp them at room temperature. While aluminum wire has a larger diameter than copper wire if the current capacity is the same, it is still lighter and cheaper. Aluminum wire itself is already in practical use in systems with a current capacity of 600A, similar to copper wire. However, because the terminals of most devices and equipment to which the wires are connected are made of copper, the combination of aluminum wire and aluminum terminals is not yet widespread. On the other hand, in electric vehicles, improving fuel efficiency is a goal through vehicle weight reduction.

[0005] In conventional electrical circuits, replacing copper wires with aluminum wires means connecting to copper wires or copper terminals on devices and equipment. However, when aluminum wires are connected to copper connectors, if moisture penetrates the connection between the copper and aluminum, the aluminum, which has a higher ionization tendency than copper, becomes the anode and the copper becomes the cathode, forming a potential difference (cell). This can cause galvanic corrosion, leading to the aluminum corroding and eventually causing the wire to break.

[0006] Several technologies have already been proposed to address the above problems. For example, in large-diameter power lines that transmit and receive high-voltage power between power plants and substations, aluminum wires are connected to copper terminals, firmly screwed together under very high loads, and the area around the connection is sealed with resin to prevent moisture from entering the connection point from the outside, thereby ensuring reliability. This suggests that if moisture does not enter the joint, corrosion failure will not occur even if there is a potential difference. However, such treatment makes the joint larger, limiting its placement and also increasing costs. Therefore, it is economically difficult to apply this treatment to all connection points in power lines that transmit and receive power between substations, or to power lines that transmit and receive power downstream of substations.

[0007] Furthermore, as an improvement, a terminal has been developed and put into practical use in which a thick copper chemical bonding plating treatment (thick copper plating treatment) is applied to a part of the aluminum connecting member that connects aluminum wires in the power transmission circuit between substations (for example, the copper-plated aluminum terminal described in Non-Patent Document 1). In this terminal, the surface of the part of the aluminum connecting member that connects to the terminal of the equipment is plated with thick copper.

[0008] In this connecting component, aluminum is located on the surface that contacts the aluminum wire, and since the same type of metal is in contact, galvanic corrosion does not occur when crimped at room temperature. In addition, the surface of the part that contacts the copper terminals of the equipment or device is plated with thick copper, and since the same type of metal is in contact, galvanic corrosion does not occur when crimped at room temperature.

[0009] On the other hand, in this connecting component, aluminum and copper are joined by applying a thick copper plating to a portion of the aluminum surface. Because dissimilar metals are in contact, a potential difference is generated at the joint surface. If water penetrates the joint between aluminum and copper, galvanic corrosion may occur, but it can withstand galvanic corrosion at least until the lifespan required for the electrical circuit. Power grids undergo regular maintenance, and the components are replaced when they reach the end of their lifespan before galvanic corrosion failure occurs. Therefore, it has been reported that this structure can be used outdoors. This indicates that there are no problems in terms of use even when exposed to wind and rain.

[0010] Previously, when connecting aluminum wires to copper connectors, moisture entering the connection between copper and aluminum would cause a potential difference (battery) to form, with aluminum, which has a higher ionization tendency than copper, becoming the anode and copper the cathode. This would lead to galvanic corrosion, causing the aluminum to corrode and potentially resulting in wire breakage. However, in this connector, aluminum and copper are joined by a thick copper plating treatment on a portion of the aluminum surface, resulting in contact between dissimilar metals. It can be used outdoors. It can withstand wind and rain without any problems. This suggests that, as long as there are no internal defects in the aluminum-copper joint of the connector, galvanic corrosion failure will not occur for the entire lifespan of the connector.

[0011] This principle can also be applied to connecting members. Even if moisture comes into contact with the interface between the aluminum part and the thick copper plated part, if there are no defects, moisture will penetrate the interior, generating a potential difference that will not cause defects in the thick copper plated part from the surface to the interior. At the very least, corrosion that would lead to failure will not progress until the end of its lifespan.

[0012] However, achieving high reliability with this configuration requires a large-area, thick copper plating process, which is very costly. Furthermore, this system is large and expensive.

[0013] Compared to directly connecting wires, connecting wires using connecting components offers greater convenience and versatility, making it a rational and economical joining method. Systems using this joining technology have been in use for over 100 years and are now widely implemented, from countries near the equator to those near the Arctic and Antarctic. Furthermore, because these systems are essential to power grids, they have been standardized under JIS (Japanese Industrial Standards).

[0014] The wires used between small substations, between switchboards in factories, and for supplying power to indoor transformers and electrical appliances in homes are short. While the aluminum-thick copper-plated systems used in power grids like those described above are a highly reliable technology standardized by JIS, the number of connection points for power distribution wires is enormous, and using such systems for all of them is not practical in terms of size and economics.

[0015] Therefore, attempts are being made to join the aluminum and copper conversion parts of the connecting components by friction welding. This is based on the idea that friction welding allows for the inexpensive and economical manufacture of smaller connecting components. The specific manufacturing method of friction welding involves cutting one wire and the other wire to a predetermined length, setting the resulting cylindrical body in a friction welding machine, bringing the two into contact, applying a suitable load, and rotating one or both for several tens of seconds to several minutes to generate frictional heat and join them. After that, the burrs of the material are removed and processed to the predetermined shape. Then, various inspections are performed. Friction welding has been used in various fields of industry for a long time, and a great deal of research has been conducted on it (for example, Non-Patent Literature 2).

[0016] While there are many research reports and inventions on friction welding, a physical joining method for aluminum and copper, it is considered extremely difficult to achieve a stable and strong bond due to the formation of intermetallic compounds (e.g., Non-Patent Documents 3 and 4). In friction welding, aluminum and copper wires are cut to predetermined lengths, the resulting cylindrical bodies are set in a friction welding machine, and a suitable load is applied. One or both of the aluminum and copper wires are rotated for several tens of seconds to several minutes, generating frictional heat to join them. Once the joint is red-hot and deformed, the rotation is stopped and a large load is applied to expel dirt, oxides, and intermetallic compounds as burrs. While reliability cannot be ensured under conditions where the joint does not red-hot, the formation of oxides and intermetallic compounds is unavoidable when the joint red-hot. Methods that remove oxides and intermetallic compounds formed in such joining using burrs are insufficient, and oxides and intermetallic compounds remain at the joint. Therefore, the quality of manufacturing depends on condition control. Destructive testing of several pieces per 100 trials is necessary. In addition, numerous inspections are required, including ultrasonic inspection of the joining surface of the joining materials, burr removal, outer circumference inspection, and outer circumference inspection of the joint after processing. This increases costs and makes the product expensive. Furthermore, it is difficult to completely remove defective parts using this method. There are reports of risks such as corrosion failure due to intermetallic compounds during use, and disconnection due to joint failure during heat cycling. Moreover, it is not economically suitable for manufacturing small to medium diameter connecting components, such as those commonly used in electrical circuits (φ3-10mm).

[0017] The friction-welded connection components were developed based on the observation that if a portion of an aluminum connection component is thickly copper-plated, and there are no internal defects in the joint between aluminum and copper, galvanic corrosion failure will not occur, and the component will last for its entire lifespan. However, friction welding leaves intermetallic compounds at the joint. Therefore, rigorous inspection is required, and the cost is high.

[0018] Many of the wires used in electric vehicles are thin wires, and it is common practice to bundle multiple thin, insulated wires (harness wires) together and connect them to terminals. A bundle of multiple insulated wires assembled into a single component (assembly) is called a wire harness.

[0019] Many wiring harnesses are short and have numerous connections to other wires and terminals. Terminals used in power and electrical grids are large and expensive, making them unsuitable for automotive applications. Furthermore, high reliability is required. In addition, replacing components of the wiring harness during maintenance is difficult. Simple, high-speed press-manufactured connectors used in applications of copper wire connection systems have low load capacity and inadequate waterproofing, so waterproof versions using resin or sealing treatments are being considered. However, this structure has limitations and cannot be used for multi-wire aluminum harnesses or wires supplying high currents.

[0020] Attempts have also been made to connect wire harnesses to terminals using ultrasonic bonding, which is simpler than friction welding. In ultrasonic bonding, it is said that by applying pressure while applying ultrasonic vibrations, the oxide film covering the surface of the aluminum wire is removed by local friction, exposing the new surface of the aluminum and allowing it to be connected to a copper terminal (for example, Non-Patent Document 5).

[0021] However, the mechanism of joining dissimilar metals by ultrasonic bonding is not fully understood. Therefore, there are concerns about its reliability. Furthermore, there are reports that, similar to friction welding, intermetallic compounds are formed at the interface between aluminum and copper during ultrasonic bonding (e.g., Non-Patent Document 6). Additionally, even if the joint is sealed with resin or other materials for waterproofing, it is susceptible to corrosion, requiring rigorous waterproofing measures, which is costly. Moreover, ultrasonic bonding machines are expensive, require high-cost materials, and have long cycle times.

[0022] Furthermore, low-output ultrasonic waves are used in medical treatment and are considered safe. However, ultrasonic waves are also used for pest control such as insects and mice, and there are concerns that they may affect living organisms depending on the frequency and output. Around the 1970s, operators complained of symptoms such as discomfort, headache, tinnitus, and earache when using devices for joining resins or cleaning machines with high-output ultrasonic waves, and strict countermeasures were required (for example, Non-Patent Document 7). To join harness wires for wire harnesses, ultrasonic waves with an output dozens to hundreds of times higher are required, and there are concerns about the health hazards to those engaged in such work.

[0023] Attempts to replace the harness wires used in automobiles and the like with aluminum wires contribute to weight reduction of the circuit due to the pursuit of economy, but do not necessarily lead to cost reduction, and there are also concerns about reliability.

Prior Art Documents

Non-Patent Documents

[0024]

Non-Patent Document 1

Non-Patent Document 2

Non-Patent Document 3

Non-Patent Document 4

[0025] As mentioned above, humanity has achieved significant results in reducing weight and costs by replacing wires with aluminum wires in power grids. However, in power distribution, power distribution lines, and automotive harnesses, we are plagued by corrosion and failure due to defects caused by intermetallic compounds at the joints between aluminum and copper.

[0026] The problem that this invention aims to solve is to provide a highly reliable wire connection component that can safely connect aluminum wires to copper wires and copper terminals, and can be manufactured at low cost. [Means for solving the problem]

[0027] The inventor first envisioned a wire connection component that allows aluminum wire to be connected to a cylindrical terminal by mechanical joining such as crimping at room temperature, and to which a cylinder or terminal for crimping copper wire can be connected, and which can handle a current of up to 600A. However, there were obstacles to this, namely defects due to the formation of intermetallic compounds at the aluminum-copper joint and corrosion failure due to potential difference. When using mechanical joining for dissimilar metal joining of aluminum and copper, it is necessary to hold the joint at very high pressure to prevent moisture intrusion. Chemical joining methods such as plating are extremely expensive. Furthermore, friction welding has the problem of intermetallic compound formation and delamination.

[0028] According to Non-Patent Document 8, methods of joining materials (metals) are classified into mechanical bonding, material bonding, and chemical bonding. Mechanical bonding includes methods such as bolting and riveting, material bonding includes methods such as solid-state bonding / diffusion bonding, fusion welding, and sintering, and chemical bonding includes methods such as plating and vapor deposition.

[0029] In addressing the above challenges, we focused on cold pressure welding (also called room temperature bonding or cold compression bonding, but hereafter referred to as cold pressure welding), which allows metals to be joined at room temperature by the material bonding (physical bonding method) described above. Cold pressure welding is a technology invented in the 1950s that joins similar or dissimilar metals by applying pressure to the joint at room temperature and without heating, causing the interface between the two to be plastically deform instantaneously. This method has conventionally been applied to non-ferrous materials, especially ductile materials such as aluminum. Cold pressure welding methods are broadly classified into overlapping and butt joints. In cold pressure welding, the joint area is plastically deformed instantaneously, and the two are joined by the atomic bonds of the metals being joined (for example, Non-Patent Literature 9). In cold pressure welding, although plastic deformation heat is instantaneously generated when pressure is applied to the joint of similar or dissimilar metals, this heat diffuses instantaneously, so oxides or intermetallic compounds are not formed at the interface between the two.

[0030] As described in Non-Patent Literature 8, in cold pressure welding, a type of solid-state bonding, an active, clean surface is exposed at the joint of the members to be joined, and the two are joined across the entire interface by the interdiffusion of atoms constituting these surfaces. This is a technique classified as solid-state diffusion bonding in Non-Patent Literature 8, and its basic bonding mechanism differs from that of riveting, which is classified as mechanical bonding. Even in the case of bonding by mechanical bonding such as riveting, localized atomic diffusion can occur at the joint, but with localized atomic diffusion, measures such as continuously applying a load to the joint are necessary to maintain the bonded state over a long period of time. On the other hand, in cold pressure welding, an atomic bond is formed over the entire interface (joint surface) of the members after bonding, so there is no need to apply a load to the joint after bonding. Furthermore, in ultrasonic bonding and friction welding, a large amount of heat is generated locally at the joint by ultrasound or friction, forming intermetallic compounds and oxides, whereas in cold pressure welding in the present invention, the joint undergoes instantaneous plastic deformation and generates heat, but the amount of heat is small and quickly diffuses. The bonded product is not hot. Therefore, intermetallic compounds and oxides are not formed. With this method, a highly reliable and stable bond can be obtained without applying a load during use. Thus, the joining mechanism differs between cold pressure welding in this invention and other joining methods.

[0031] There are no reports comparing cold and hot pressure welding in metal joining, and even in the case of joining aluminum and copper, many experts believe that hot or warm pressure welding is more advantageous for joining metals. For this reason, the use of cold pressure welding in the manufacture of wire connection components had not been considered. However, hot welding, such as electric resistance welding and laser welding which involve melting, presents problems with intermetallic compounds. Warm welding involves joining by rolling at temperatures higher than the oxidation temperatures of aluminum and copper, and there are many reports of phenomena such as uncertainty in joint strength due to oxidation of the joint surface.

[0032] The manufacturing process for joining dissimilar metals using cold pressure welding is almost identical to that using friction welding, except that the joining method is changed from friction welding to cold pressure welding, and inspection is simplified. Aluminum and copper wires are cut to the specified lengths, the cylindrical shapes are cleaned, and then set in a cold pressure welding machine. A large load is applied to bring them into contact, causing plastic deformation in less than one second, which generates burrs from the joint. These burrs are removed during shaping. Inspection is basically only required for the finished product, and inspection costs are significantly lower compared to jointed parts manufactured by friction welding. Furthermore, it is highly resistant to corrosion fracture, and fracture due to intermetallic compounds is not considered to occur.

[0033] There are no restrictions on the structure of a cold welding machine; it is not a difficult machine to manufacture if you understand the principle of cold welding. Furthermore, it is possible to incorporate the cold welding machine's structure into a high-speed press during manufacturing. Additionally, it is possible to incorporate the cold welding machine's structure into a cold or hot forging machine to quickly produce the shape of joined parts.

[0034] When replacing copper wire with aluminum wire, it is desirable to construct a system with a current rating of 600A by crimping the copper wire to the connecting component, similar to the copper wire system. It is already known that it is possible to construct a system with a current rating of 600A by crimping copper wire or aluminum wire together if the connecting part is made of the same material.

[0035] Based on the above, the wire connection member according to the present invention is: A first conductive part having a first cylindrical portion into which an aluminum wire is inserted, which is made of aluminum with a purity of 99.9% or higher, A conductive part located adjacent to the first conductive part, which is made of copper or a copper alloy and has a second cylindrical part into which a copper wire is inserted or a terminal for connecting to equipment, Atomic bonding portion formed at the interface between the first conductive portion and the second conductive portion It is characterized by having the following features.

[0036] Furthermore, the method for manufacturing a wire connection member according to the present invention is A step of preparing a columnar first conductive member made of aluminum with a purity of 99.9% or higher, A step of preparing a columnar second conductive member made of copper or a copper alloy, A step of joining the first conductive member and the second conductive member by cold pressure welding while they are in contact with each other, The process of forming a hole in the first conductive member after joining, into which an aluminum wire is inserted, The process involves forming a hole in the second conductive member after joining, or a terminal for connecting to equipment, into which a copper wire is inserted. Equipped with [Effects of the Invention]

[0037] The inventor has succeeded in inventing a new joining component capable of handling currents up to 600A, which is necessary for replacing copper wires with aluminum wires in target electrical circuits. The reliability of cold pressure welding was discovered by chance when aluminum foil was cut and the foil was joined at room temperature. As mentioned above, hot or warm welding is the conventional method for joining metals, and the use of cold pressure welding in the manufacture of wire connection components had not been considered. For this reason, there are almost no reports on research and development of cold welding or reports on practical use. In this context, as is still used today for extending the length of single-strand copper wires (φ0.1mm~φ5mm), cold pressure welding directly joins wires without causing thermal deterioration of materials and additives or defects. Furthermore, cold welding requires less manufacturing equipment and has high productivity compared to other methods. No problems occur when drawing the wire after joining, and it has high strength and reliability. It is a highly reliable joining technology with a proven track record of being used worldwide for extending the length of single-strand copper and aluminum wires for over 60 years. The equipment is also commercially available. Thus, cold pressure welding is an ideal technique for joining aluminum and copper, as in the present invention. However, a dedicated cold welding machine is required to directly join wires. Although the joining time is short, the setup time is long, making it inconvenient and unsuitable for mass production. The solution is to develop connecting components that utilize this method. Furthermore, it is not possible to directly join multi-wire wires (bundles of multiple wires or strands of multiple wires) such as harness wires.

[0038] Evaluation of the new connecting member according to the present invention revealed that, because aluminum and copper are joined by cold pressure welding at room temperature, no fracture due to intermetallic compounds occurs during heat cycling even when used in electrical circuits. Furthermore, it is more resistant to corrosion fracture than joints formed by conventional techniques, and naturally has a longer lifespan than conventional joints, so no problems occur in the joint until the required lifespan for the electrical circuit is reached. Moreover, there is almost no risk of accidents caused by joint failure or other issues. In addition, the present invention does not cause the formation of intermetallic compounds, aggregation of additives (oxides of materials, deposits, etc.) on or near the outer circumference of the joint, or the formation of voids, which can occur with hot welding.

[0039] The connecting members according to the present invention can be broadly classified into two types: one in which both ends are cylindrical (for example, cylindrical), and another in which one end is cylindrical (for example, cylindrical) and the other end has a terminal for connecting equipment. Furthermore, the connecting members according to the present invention can connect not only single wires but also bundles of multiple wires. Of course, it is possible to connect multiple wires to each other or to connect multiple wires to terminals.

[0040] Inexpensive devices and jigs for crimping wires and connectors at room temperature are commercially available for use at construction sites and factories. This method allows for parallel crimping of wires and terminals, making it suitable for mass production. It is also ideal for automotive wiring harnesses.

[0041] In the novel joining member according to the present invention, single-strand or multi-strand aluminum wires can be connected to the first conductive part. Furthermore, single-strand or multi-strand copper wires can be connected to the second conductive part. The second conductive part may have terminals formed on it, such as a plate or a circular shape. In this invention, it is not necessary to cold-crimp the aluminum wires or copper wires to the first or second conductive part. To improve the adhesion between the aluminum and copper wires, they may be connected at a warm temperature, provided that this does not adversely affect the cold-press-welded aluminum and copper joint. Additionally, the aluminum wires or copper wires may be fixed to the first or second conductive part by mechanical joining methods other than crimping (such as screw fastening or fitting).

[0042] While this invention can handle currents from 5 to 600A, the most commonly used applications are for circuits carrying 5 to 50A, with connection members having an outer diameter of φ3 to 10mm. Producing such small-diameter connection members by friction welding is costly. On the other hand, cold welding, as in this invention, is well-suited for manufacturing such small-diameter connection members. Furthermore, cold welding is fast, and by integrating a cold welding machine into a high-speed press, high-speed and inexpensive products can be produced, resulting in high productivity. Moreover, by integrating a cold forging machine into the cold welding machine, high-speed and inexpensive products can be produced. This makes it possible to mass-produce connection terminals at low cost.

[0043] When comparing the cost of connecting aluminum wires using connecting components with the cost of connecting copper wires of the same dimensions and shape, the cost is reduced by the difference in cost due to the change from copper wire to aluminum wire. The raw material cost of aluminum wire is cheaper than that of copper wire, and therefore cheaper than connecting copper wires. In addition, although the present invention requires costs for cold pressure welding, these can be kept low by automating the manufacturing process and mass-producing. Furthermore, the shape of aluminum can be processed in the same way as copper. The same applies to inspection. In this way, by replacing copper wire with aluminum wire of a certain length, both weight reduction and cost reduction are achieved.

[0044] The inventors initially manufactured a wire joint component by joining a cylindrical first conductive component made of general pure aluminum (99.0% purity) or an aluminum alloy with a second conductive component made of copper or a copper alloy by cold pressure welding. It was confirmed that this wire joint component also had sufficient reliability compared to conventional ones.

[0045] High-purity aluminum is naturally more expensive than pure aluminum or alloy aluminum. However, the amount of aluminum used in terminals is small, and the benefits of switching from copper to aluminum are substantial enough that this is not a problem. Also, while the mechanical strength of aluminum is slightly lower than that of copper, this can be addressed by increasing the diameter or length of the terminals if mechanical strength becomes a concern.

[0046] Wire joint components can be used as public infrastructure, for example, to supply power from power plants to end devices such as electrical appliances. There are countless wire joint components used in public infrastructure, and they require extremely high reliability. This same extremely high reliability is required not only in public infrastructure but also in automotive circuits, etc. From this perspective, our verification revealed that in order to obtain the high level of reliability suitable for use in public infrastructure, the first conductive component must be made of aluminum with a purity of 99.9% or higher. Furthermore, for the second conductive component, no defects occurred even when using commonly used copper, tough pitch copper, or copper alloys, and high reliability suitable for the above-mentioned applications was obtained. [Brief explanation of the drawing]

[0047] [Figure 1] A diagram showing the main components of one embodiment of a wire connection member according to the present invention. [Modes for carrying out the invention]

[0048] Hereinafter, embodiments of the wire connection member and its manufacturing method according to the present invention will be described with reference to the drawings. Note that, in order to clearly illustrate the configuration of each part, the scale of each part in the drawings has been appropriately changed from the actual scale.

[0049] One of the features of the manufacturing method of the wire connector 1 of this embodiment is that it uses cold pressure welding. In the wire connector 1 of this embodiment, failure due to galvanic corrosion caused by the potential difference between copper and aluminum does not occur. The joint in the wire connector 1 of this embodiment is an extremely thin joint layer at the atomic level, and no intermetallic compounds are formed at the interface between aluminum and copper, so even if moisture penetrates the joint, corrosion will not progress.

[0050] The advantage of the wire connector 1 in this embodiment is that a system with a permissible current of 600A can be constructed by crimping aluminum wires to the connector at room temperature, crimping copper wires to the connector at room temperature, or crimping the connector at room temperature to form copper terminals, similar to a copper wire system.

[0051] Cold welding is a technology discovered approximately 80 years ago. Cold welding is a technique that joins materials at room temperature without heating by applying instantaneous pressure to the joint between aluminum, copper, or dissimilar metals, causing plastic deformation. The cold welding equipment has a capacity of 200 kgf / mm². 2 Cold welding has been used to join aluminum wires to each other or copper wires to each other, by instantaneously applying pressure for less than one second. Cold welding does not necessarily require a non-oxidizing atmosphere and can be performed in the atmosphere. Also, heating of the joint is unnecessary and it can be performed at room temperature. The time required for cold welding is less than one second, and dissimilar metals can be joined with the extremely thin atomic bonding layer that is formed. Cold welding is a type of physical joining and is sometimes called atomic joining or atomic diffusion joining. By optimizing the joining conditions, the joint surface becomes stable, and a high-quality, highly reliable joint state can be obtained.

[0052] Cold welding is a room-temperature joining method, and no oxidation or intermetallic compounds are formed at the joint. While some heat may be generated when metal atoms come into contact and undergo instantaneous plastic deformation, the heat-generating layer is extremely thin, as described above, and the generated heat dissipates quickly. Therefore, the joined material after cold welding is not hot to the touch, and there is no discoloration due to heat. Consequently, there is no discoloration of the copper portion of the wire joining component after manufacturing. Furthermore, there is virtually no possibility of failure due to galvanic corrosion. Cold welding itself was developed for the purpose of joining copper wires together. When joining aluminum and copper, some reports suggest that a pressure approximately 40% lower than that used when joining copper to copper should be applied. There are also reports that, although the equipment becomes larger, applying a higher pressure results in a stronger and more stable joint. In this embodiment, the same pressure (200 kgf / mm²) as when joining copper to copper is used. 2 Aluminum and copper were joined by applying ).

[0053] Cold pressure welding is a technique that joins dissimilar metals at room temperature without heating by applying pressure to the joint. Many people involved in the field mistakenly believe that it is unreliable because heat is required for joining. However, there are no reports verifying this. Rather, as discovered in this invention, cold pressure welding is ideal for joining aluminum and copper in wire connection components. First, since the joining is done at room temperature, there is no possibility of intermetallic compounds forming. The joint is made up of very thin atomic bonds that are highly reliable.

[0054] Cold pressure welding has been used, for example, for joining long single-strand copper wires or aluminum wires for the past 70 years. The resulting joint does not delaminate or break down at the joint even after wire drawing. Furthermore, numerous tests have been conducted to check for corrosion of copper wires joined by cold pressure welding using salt spray, and no problems have been observed.

[0055] First, although the atomic bonds formed by cold welding are extremely thin, no intermetallic compounds are present at the joint, and this method has a proven track record of high strength and reliability as a technique for joining single-wire electric wires. When a predetermined pressure is applied to the cold welding apparatus, burrs are discharged from the joint between aluminum and copper, completing the joining process. It is advisable to clean the surface of the aluminum and copper wires before cold welding. This allows any thin oxide film or atmospheric gases formed on the surface to be discharged as burrs during welding, thus avoiding problems such as damage caused by oxides.

[0056] There are no intermetallic compounds at this joint, and the two metals are joined with extremely high strength. The joint strength correlates with the pressure applied during joining; at pressures below 50% of the pressure used for joining copper to copper, no burrs are formed, and when the strength is tested, the joint surface may delaminate. Upon observation of the delaminate surface, voids were found in the wire joint members manufactured with the above-mentioned pressure below 50%, which are thought to have been formed by air being trapped during joining.

[0057] Figure 1 shows a cross-sectional view of the wire connection member 1 of this embodiment. The wire connection member 1 comprises a first conductive part 10 made of aluminum or an aluminum alloy and a second conductive part 20 made of copper or a copper alloy. The first conductive part 10 has a structure that combines a large-diameter cylindrical part and a small-diameter cylindrical part, and a first hole 111 is formed in the portion corresponding to the large-diameter cylindrical part. The second conductive part 20 has a cylindrical part with the same diameter as the small-diameter cylindrical part of the first conductive part 10, and a second hole 211 is formed therein. An atomic bonding part 30 is formed at the interface between the first conductive part 10 and the second conductive part 20, and the first conductive part 10 and the second conductive part 20 are firmly joined by this atomic bonding part 30.

[0058] When connecting the aluminum wire and the copper wire, the aluminum wire 12 is inserted into the first hole 111 and the copper wire 22 is inserted into the second hole 211. Then, the aluminum wire 12 and the copper wire 22 are fixed in place by crimping the outer circumferences of the first conductive part 10 and the second conductive part 20, respectively.

[0059] Household wiring, home appliances, and harnesses are commonly used with currents in the range of 5 to 50A. Therefore, in this embodiment, a wire connector capable of supplying a current of 20A, which is considered the most common allowable current, was manufactured.

[0060] As described above, in the wire joint member 1 of this embodiment, a sleeve terminal with the most easily understood basic configuration is selected, with a cross-sectional area of ​​1.25 mm². 2 Aluminum wire 12 (sq1.25) with a current rating of 20A and a cross-sectional area of ​​0.75mm² 2 A copper wire 22 (sq0.75) with a current rating of 20A was connected. Note that copper has a higher electrical conductivity than aluminum, so for the same current rating, the copper wire will be thinner than the aluminum wire. Also, the outer diameter of the connecting member will be smaller.

[0061] If the dimensions or crimping conditions of the cylindrical part of the wire joint component and the wire are incorrect, loosening will occur during the heat cycle, increasing resistance and leading to heat generation. The inner diameter d and outer diameter D of the copper wire connection part of the wire joint component were based on JIS standards, and for the aluminum wire connection part, JIS standards and commercially available products were used as references. In addition, since there are commercially available cylindrical aluminum wire connectors manufactured by friction welding, these were also used as references to determine the shape and dimensions of the connector component and to consider evaluation methods. For the crimping device, a dedicated cold-pressure welding device was used, and a jig suitable for the outer diameter D of the connection part of the aluminum wire and copper wire was used.

[0062] The outer diameter of the large-diameter cylindrical portion of the first conductive part 10 was Φ3.4 (±0.2) mm, and the outer diameter of the small-diameter cylindrical portion of the first conductive part 10 and the second conductive part 20 was Φ2.2 (±0.2) mm. The inner diameter of the first hole 111 was Φ1.7 (±0.1) mm, and the inner diameter of the second hole 211 was Φ1.2 (±0.1) mm. Furthermore, the length of the first conductive part 10 (length in the transverse direction of the paper) was 45 mm, and the length of the second conductive part 20 was 40 mm.

[0063] In this embodiment, the wire connection member 1 is manufactured using a cold welding machine. In the prototype of the wire connection member in this embodiment, an aluminum material and a copper material having the above shape were joined using a PWM M101 cold welding machine for electric wires, sold by Toyo International Co., Ltd. The aluminum and copper materials were butted together in the welding machine and welded at 200 kgf / mm². 2 The pressure was applied for 1 second. Although aluminum and copper can be cold-welded at lower pressures than copper-to-copper, increasing the applied pressure allows for the discharge of more burrs from the joint surface, thereby improving the joint strength. At this time, any small amount of dirt or oxides present at the interface before joining can also be discharged to the outside as burrs. The outer circumference and joint surface of the prototype wire joint member were observed using an SEM, and no defects such as voids were found. Furthermore, various evaluations were performed as described below, and all passed.

[0064] Next, the manufacturing method of the wire connection member of this embodiment will be described.

[0065] First, a columnar first conductive member made of aluminum and a columnar second conductive member made of copper are prepared (member preparation step).

[0066] Next, the end faces of the first conductive member and the end face of the second conductive member are brought into contact and positioned (positioning step).

[0067] Then, the end faces of the first conductive member and the second conductive member are brought into contact, and pressure is applied from the side opposite the joining surface toward the joint (from both sides) (pressing step). This pressing step is static in that a constant force is applied uniformly to the joining surface. The pressing step is performed in a room temperature environment (for example, in the range of 10°C to 35°C), and the pressure applied during the above pressing is 120 kgf / mm or more. 2 300 kgf / mm 2It is preferable to apply a pressure within the following range for 0.5 to 5 seconds and join them so as to form burrs. As a result, a joint portion (atomic bond portion 30) in which aluminum and copper are atomically bonded is formed at the contact portion between the first conductive member 15 and the second conductive member 25. A higher pressure results in a more stable joint state, but the apparatus becomes larger. However, if the pressure is low, the joint state becomes unstable. A joining time of 0.5 seconds is sufficient, and exceeding 5 seconds may sometimes make the joint state unstable. Note that the above temperature range, pressure range, and time range are examples of preferable ranges determined experimentally and may be appropriately changed according to the shape and size of the members to be actually joined, and the implementation conditions of the manufacturing method of the wire connection member according to the present invention are not limited only to this range.

[0068] Worldwide, the joining of copper wires to each other, the joining of copper wires and copper terminals, the joining of aluminum wires to each other, the joining of aluminum wires and copper wires, and the joining of aluminum wires and copper terminals are carried out in a number amounting to several billions in total. If the joint portion peels off, it will result in a great disaster such as a fire. Several cases have been reported in the past. For this reason, customers considering new joints for mass use may sometimes request confirmation that there are zero defects even if 100,000 products are prototyped. Therefore, the following experiments were conducted.

[0069] As described above, the high-speed press apparatus is modified, and after the first conductive member and the second conductive member are cold-welded (1 piece / 1 second), the burrs at the joint portion are removed at high speed. As described above, when removing burrs from a large number of joined products, high-speed trimming (1 piece / 1 second) is to be performed. In high-speed trimming, a high peeling pressure is applied to the joint portion. Trimming under such pressure application may correspond to a full inspection of the joint portions of defective products. By applying a pressure of 50% or more of the pressure during cold-welding (in the above example, 60 kgf / mm 2 or more up to 150 kgf / mm 2 within the following range of pressure) during trimming, it is possible to reduce the remaining voids in the joint portion.

[0070] A first hole 111 is formed in the first conductive part 10, which is made of a first conductive member, for inserting an aluminum wire 12, and a second hole 211 is formed in the second conductive part 20, which is made of a second conductive member, for inserting a copper wire 22. The first hole 111 and the second hole 211 only need to be shaped in such a way that the aluminum wire 12 and copper wire 22 can be inserted and crimped. Therefore, the periphery of the hole may be closed, or a part of the periphery of the hole may be open (for example, a slit may be formed on the side circumference of the cylindrical body). Alternatively, instead of forming a hole 211, it may be processed into the shape of a terminal for connecting to equipment.

[0071] In the above example, the first conductive member and the second conductive member were cold-press-welded as described above, and then the first hole 111 and the second hole 211 were formed. However, if the sides of these holes have a certain thickness and the shape is unlikely to change even after cold-press-welding, the first conductive member with the first hole 111 formed therein and the second conductive member with the second hole 211 formed therein may be cold-press-welded separately.

[0072] If the temperature at the location where the above pressing process is performed is high, the joint may be cooled by an appropriate method such as blowing cold air onto it. In cold pressure welding, although plastic deformation heat is instantaneously generated when pressure is applied to the joint of dissimilar metals, this heat dissipates instantly, so no intermetallic compounds are formed at the interface between the two. Therefore, it is possible to manufacture a wire connection member 1 in which no intermetallic compounds are present at the joint of dissimilar metals. Furthermore, in order to prevent the formation of aluminum or copper oxides at the joint due to the intrusion of oxygen, it is preferable to perform the pressing process in an oxygen-free atmosphere (for example, under a non-oxygen gas displacement atmosphere such as nitrogen, under a vacuum atmosphere, or under blowing of a non-oxygen gas such as nitrogen).

[0073] Next, we will describe the tests conducted to evaluate the characteristics of the wire connection components manufactured using the above process.

[0074] <Heat cycle test> Electrical circuits consisting of commonly used wires and wire connectors are designed to melt due to overheating if a current twice the allowable current (rated current) is continuously passed through them for more than two minutes, and are usually protected by circuit breakers. The rated current is the maximum current value that electrical equipment and electronic components can safely handle, and its value is determined according to the thickness (cross-sectional area) of the wire. In other words, if a circuit can withstand repeated applications of a current twice the rated current for two minutes, it can be judged to be sufficiently suitable for practical use. Therefore, in this heat cycle test, first, a current of 20A was passed and the voltage was measured, then a current twice the rated current (20A) (40A) was passed through for two minutes, and then the current supply was stopped for the following five minutes. This heat cycle was performed 50 times, and after the heat cycle, a current of 20A was passed again and the voltage was measured. The increase in electrical resistance was calculated from the change in the measured voltage (voltage difference) before and after the heat cycle test, and the pass criterion was that the increase was less than 20% of the electrical resistance value before the heat cycle test. In this test, the quality of the wire connection components was determined by evaluating them under a harsh operating environment in which a current twice the rated current of 40A was repeatedly passed through them.

[0075] <Corrosion Test> Various corrosion tests for electrical wires and circuits have been reported. Typically, wire connectors are moistened with a 4% salt solution and left for a week, after which their pass / fail status is determined by their appearance and resistance changes. In this test, first, a 20A current was passed through and the voltage was measured. Then, the wire connectors were moistened with a 4% salt solution and left for two weeks, after which a 20A current was passed through and the voltage was measured again. The increase in electrical resistance was then calculated from the change in the measured voltage (voltage difference) before and after moistening with salt water, and the pass / fail criterion was that this increase was less than 20% of the electrical resistance value before moistening with salt water. In this test, the quality of wire connectors was judged by evaluating them under a harsh operating environment, which involves moistening with salt water for two weeks, twice the period of a normal corrosion test.

[0076] <Corrosion test after heat cycling> This test is a new evaluation method that combines a heat cycle test and a corrosion test. It is a more rigorous evaluation method conducted for comparison with connecting members manufactured by friction welding, which are already in practical use. In this test, a corrosion test is performed after the heat cycle described above. A current of 20A is passed through the material before and after both tests, and the voltage is measured. The electrical resistance value is calculated from the change in the measured voltage, and the pass criterion is that the increase in electrical resistance value is less than 20% of the value before both tests were performed.

[0077] In addition to a reference example having a configuration corresponding to the wire joint member 1 of the above embodiment, three comparative examples were prepared, and the above tests were performed on each of them.

[0078] <Reference example> The wire connection member 10 (first conductor 11 and second conductor 21) manufactured in the above embodiment is subjected to a temperature of 200 kgf / mm² at room temperature. 2 An example was a wire connector 1 in which an aluminum wire 12 (sq 1.25) and a copper wire 22 (sq 0.75) were fixed, using a joint 30 formed by atomic bonding of aluminum and copper, which is created by cold pressure welding with the pressure applied for 1 second.

[0079] <Comparative Example 1> Comparative Example 1 was a wire connector that used a wire connector of the same shape and size as described above (however, one in which aluminum and copper are joined by friction welding) and fixed the same aluminum wire and copper wire as in the example.

[0080] <Comparative Example 2> Comparative Example 2 was created by using a wire connector (made entirely of copper) of the same shape and size as described above, and fixing the same aluminum and copper wires as in the reference example.

[0081] <Comparative Example 3> Comparative Example 32 was created by using a wire connector (made entirely of aluminum) of the same shape and size as described above, and fixing the same aluminum wire and copper wire as in the reference example.

[0082] Table 1 shows the results of the three tests performed on each of the above reference examples and comparative examples 1-3. [Table 1]

[0083] As shown in the table above, only the reference example passed all three tests. As stated above, these three tests were conducted under conditions more severe than those typically expected in the intended usage environment, and it has been proven that the reference example wire connector 1 can be used safely even under such extremely harsh conditions.

[0084] Wire connection components can be used as public infrastructure, for example, to supply power from power plants to end devices such as electrical appliances. There are countless wire connection components used in public infrastructure, and they require extremely high reliability. This same high reliability is also required for applications such as automotive electrical circuits. Therefore, we further verified the reliability of wire connection components by mass-producing them.

[0085] Similar inventions for cold joining of aluminum or aluminum alloys with copper have existed in the past, but they have not become widespread. This is likely because sufficient testing of a large number of products before practical application was not carried out, and reliability was not adequately confirmed. Problems were only discovered after the product was actually commercialized and mass-produced. Furthermore, although defects occurred with an extremely low probability, the cause could not be determined because the aggregation of the defective areas was small and the joint was thin.

[0086] In the above reference example, the first conductive part 10 was fabricated using a columnar body made of general pure aluminum (99.0% purity), which is widely used in electric wires and the like. However, in the following verification, the first conductive part 10 was also fabricated using columnar members made of high-purity aluminum (99.9% purity or higher) and aluminum alloy. The elements added to the aluminum alloy include, for example, silicon (Si), copper (Cu), magnesium (Mg), zinc (Zn), and manganese (Mn), and are selected based on properties such as corrosion resistance, strength, and workability according to the intended use. In this verification, a high-strength aluminum alloy with Mg and Si added to aluminum was used. Furthermore, the second conductive part 20 was fabricated using columnar members made of tough pitch copper (copper containing a trace amount of oxygen of about 0.02-0.05%), oxygen-free copper, and alloy copper (alloy with Ag).

[0087] For each combination of the first conductive part 10 and the second conductive part 20, the columnar first conductive part 10 and the columnar second conductive part 20 were joined by cold pressure welding, burrs were removed from the joint, and first holes 111 and second holes 211 were formed in the first conductive part 10 and the second conductive part 20, respectively, to manufacture the wire joining member 1. In this verification, 100,000 joints (cold-press-welded and deburred) were fabricated for each combination of the first conductive member and the second conductive member, and their condition was checked. Only those joints that did not show any defects were used to form the first hole 111 and the second hole 211, and the wire joint member 1 was manufactured.

[0088] Table 2 shows the verification results. Circles in the table indicate that no defective products were found, and the numbers indicate the number of defective products. [Table 2]

[0089] As shown in Table 2, in the cases where the first conductive part was made using a columnar body made of high-purity aluminum (Examples 1-3), delamination did not occur regardless of the material of the second conductive part, and no problems occurred during the process of forming the first hole 111 and the second hole 211 in the joint to make the wire joint member 1.

[0090] On the other hand, in the cases where the first conductive part was made using columnar bodies made of pure aluminum (Comparative Examples 4-6) or columnar bodies made of alloy aluminum (Comparative Examples 7-9), no problems occurred at the time of cold pressure welding, but after deburring, delamination occurred at the joint in several cases (4-9 cases). In the case of Comparative Examples 4-9, since delamination was confirmed in several cases, the verification was terminated without forming the first and second holes.

[0091] Considering the results of the above tests together, while the wire joint members of Comparative Examples 4-9 also offer higher reliability compared to conventional wire joint members, they may not be suitable for use in situations where large quantities of wire joint members are used, such as in public infrastructure, and where high reliability is required for all of them. In contrast, the failure rate of the wire joint members of Examples 1-3 is less than ppm, and these wire joint members can withstand large-scale use and situations requiring extremely high reliability.

[0092] With high-purity aluminum, even when the type of copper changed, there were zero defects due to delamination in each of the 100,000 wire joint components. Furthermore, the outer surface of the joint was visually inspected for all wire joint components, and there was no opening of the joint surface, which is a sign of impending delamination. This means that even with a total of 300,000 components using the three types of copper in Examples 1-3, there were no defects. Thus, high reliability was confirmed for the wire joint components in Examples 1-3.

[0093] The joint in the wire joining member 1 of this embodiment is an extremely thin joining layer at the atomic level. In cold welding at room temperature, aluminum has low fluidity. In general pure aluminum and alloy aluminum materials, if the proportion of impurities and additives of dissimilar elements at the aluminum interface of the bonding surface with copper exceeds a certain level, some of the impurities and additives may remain or aggregate at the bonding interface without being ejected as burrs. In particular, when dissimilar elements form layers, it is thought that the location where the dissimilar metals aggregated becomes the starting point for deburring during trimming.

[0094] If an intermetallic compound were to form at the joint between aluminum and copper in the wire joint member of the present invention, Examples 1, 2, and 3 would also fail. It is believed that the higher the purity of the aluminum, the higher the reliability. However, the higher the purity, the higher the cost of the aluminum material. Considering the balance between reliability and cost, it is considered that a purity of 99.9% or higher and 99.99% or lower is an appropriate range for the aluminum material constituting the first conductive part 10.

[0095] The above embodiments and examples are merely examples and can be modified as appropriate in accordance with the spirit of the present invention. In the above embodiments, a wire connector was used to connect an aluminum wire and a copper wire, but an aluminum wire may be connected to a wire connector that has terminals of an appropriate shape formed thereon for connection to various devices.

[0096] The numerical values ​​and shapes given in the above embodiments and examples are merely examples and can be modified as appropriate within the scope of satisfying the requirements described in Claim 1 of this application.

[0097] [Pattern] It will be obvious to those skilled in the art that the exemplary embodiments described above are specific examples of the following embodiments.

[0098] (Section 1) A wire connecting member according to one aspect of the present invention is A first conductive part having a first cylindrical portion into which an aluminum wire is inserted, which is made of aluminum with a purity of 99.9% or higher, A conductive part located adjacent to the first conductive part, which is made of copper or a copper alloy and has a second cylindrical part into which a copper wire is inserted or a terminal for connecting to equipment, Atomic bonding portion formed at the interface between the first conductive portion and the second conductive portion It is equipped with.

[0099] (Section 6) The method for manufacturing the wire connection member relating to paragraph 6 is: A step of preparing a columnar first conductive member made of aluminum with a purity of 99.9% or higher, A step of preparing a columnar second conductive member made of copper or a copper alloy, A step of joining the first conductive member and the second conductive member by cold pressure welding while they are in contact with each other, The process of forming a hole in the first conductive member after joining, into which an aluminum wire is inserted, The process involves forming a hole in the second conductive member after joining, or a terminal for connecting to equipment, into which a copper wire is inserted. Includes.

[0100] In the wire connection member described in paragraph 1, a first conductive part, which is made of aluminum with a purity of 99.9% or higher and has a first cylindrical part into which an aluminum wire is inserted, and a second conductive part, which is made of copper or a copper alloy and has a second cylindrical part into which a copper wire is inserted or a terminal for connecting to equipment, are joined by an atomic bond formed at the interface between the two. Conventional wire connection members were manufactured at a hot temperature, which made it possible for delamination or galvanic corrosion to occur due to intermetallic compounds formed at the interface between aluminum and copper. In contrast, in the wire connection member described in paragraph 1, since aluminum with a purity of 99.9% or higher and copper or a copper alloy are joined by an atomic bond, an aluminum wire can be safely connected to a copper terminal or copper wire with high reliability without causing problems such as delamination or fracture due to galvanic corrosion. In particular, by using a first conductive part made of aluminum with a purity of 99.9% or higher, a wire connection member with extremely high reliability, with a defect rate of less than 0 / 100,000, can be obtained.

[0101] Furthermore, the wire connection member described in paragraph 1 can be manufactured simply and at low cost, regardless of the size of the joint, by applying a predetermined pressure to the interface between aluminum and copper at room temperature and without heating (cold pressure welding), as described in paragraph 6. While the above-mentioned cylindrical shape is typically cylindrical, it may also be a cylindrical shape with an elliptical or polygonal cross-section.

[0102] (Section 2) The wire connection member relating to paragraph 2 is, in the wire connection member relating to paragraph 1, After inserting and crimping an aluminum wire into the first cylindrical section and crimping it, and inserting and crimping a copper wire into the second cylindrical section, a current twice the rated current (determined according to the thickness of the aluminum wire and the copper wire) is applied for 2 minutes, and then the current supply is stopped for the following 5 minutes. After performing this cycle 50 times, the increase in electrical resistance is less than 20%.

[0103] (Section 3) The wire connection member relating to paragraph 3 is, in the wire connection member relating to paragraph 1 or 2, After inserting an aluminum wire into the first cylindrical part and crimping it, and inserting a copper wire into the second cylindrical part and crimping it, the device is moistened with salt water and left for two weeks. Then, a rated current determined according to the thickness of the aluminum wire and the copper wire is applied for two minutes, and the current supply is stopped for the following five minutes. After performing this cycle 25 times, the increase in electrical resistance is less than 20% of the electrical resistance before immersion in salt water.

[0104] (Section 4) The wire connection member relating to paragraph 4 is, in any of the wire connection members relating to paragraphs 1 to 3, An aluminum wire is inserted into the first cylindrical part and crimped, and a copper wire is inserted into the second cylindrical part and crimped. A current twice the rated current, determined according to the thickness of the aluminum wire and the copper wire, is applied for 2 minutes, and then the current supply is stopped for the following 5 minutes. This cycle is repeated 50 times. After that, the device is soaked in salt water and left for 1 week, and then the rated current is applied for 2 minutes, followed by the current supply being stopped for the following 5 minutes. The increase in electrical resistance after this cycle is less than 20% of the electrical resistance before immersion in salt water.

[0105] The aforementioned rated current refers to the maximum current value that can be safely handled, determined according to the thickness (cross-sectional area) of the aluminum wire inserted into the first cylindrical part and the copper wire inserted into the second cylindrical part. The wire connection members described in paragraphs 2 to 4 can withstand use under conditions exceeding those practically expected, and therefore can be used more safely.

[0106] (Section 5) The wire connection member relating to paragraph 5 is, in any of the wire connection members relating to paragraphs 1 to 4, The first cylindrical portion has a hole open only on the side into which the aluminum wire is inserted, and a flat surface without a hole is formed on the opposite side of that surface. The second cylindrical portion has a hole that is open only on the side into which the copper wire is inserted, and a flat surface without a hole is formed on the opposite side of that side.

[0107] In the wire connection member relating to paragraph 5, the first conductor and the second conductor are joined on a flat surface without holes, allowing them to be crimped together more firmly. [Explanation of Symbols]

[0108] 1…Wire connection component 10…First conductive part 11…First cylindrical part 111...First hole 12…Aluminum wire 15…First conductive member 20...Second conductive part 21...Second cylindrical part 211...Second hole 22...Copper wire 25...Second conductive member 30…Atomic bonding part

Claims

1. A first conductive part having a first cylindrical portion into which an aluminum wire is inserted, which is made of aluminum with a purity of 99.9% or higher, A conductive part located adjacent to the first conductive part, which is made of copper or a copper alloy and has a second cylindrical part into which a copper wire is inserted or a terminal for connecting to equipment, Atomic bonding portion formed at the interface between the first conductive portion and the second conductive portion A wire connection member characterized by comprising the following features.

2. After inserting and crimping an aluminum wire into the first cylindrical section and crimping it, and inserting and crimping a copper wire into the second cylindrical section, a current twice the rated current (determined according to the thickness of the aluminum wire and the copper wire) is applied for 2 minutes, and then the current supply is stopped for the following 5 minutes. After performing this cycle 50 times, the increase in electrical resistance is less than 20%. The wire connection member according to feature 1.

3. After inserting and crimping an aluminum wire into the first cylindrical section and crimping a copper wire into the second cylindrical section, the equipment is moistened with salt water and left for one week. Then, a rated current, determined according to the thickness of the aluminum and copper wires, is applied for two minutes, followed by a five-minute period of no current supply. This cycle is repeated 25 times, and the increase in electrical resistance after this period is less than 20% of the electrical resistance before immersion in salt water. The wire connection member according to feature 1.

4. An aluminum wire is inserted into the first cylindrical section and crimped, and a copper wire is inserted into the second cylindrical section and crimped. A current twice the rated current is applied for 2 minutes, and then the current supply is stopped for the following 5 minutes. This cycle is repeated 50 times. After that, the material is moistened with salt water and left for 1 week. Then, a rated current determined according to the thickness of the aluminum wire and the copper wire is applied for 2 minutes, and then the current supply is stopped for the following 5 minutes. After repeating this cycle 50 times, the increase in electrical resistance is less than 20% of the electrical resistance before immersion in salt water. The wire connection member according to feature 1.

5. The first cylindrical portion has a hole open only on the side into which the aluminum wire is inserted, and a flat surface without a hole is formed on the opposite side of that surface. The second cylindrical portion has a hole open only on the side into which the copper wire is inserted, and a flat surface without a hole is formed on the opposite side. The wire connection member according to feature 1.

6. A step of preparing a columnar first conductive member made of aluminum with a purity of 99.9% or higher, A step of preparing a columnar second conductive member made of copper or a copper alloy, A step of joining the first conductive member and the second conductive member by cold pressure welding while they are in contact with each other, The process of forming a hole in the first conductive member after joining, into which an aluminum wire is inserted, The process involves forming a hole in the second conductive member after joining, or a terminal for connecting to equipment, into which a copper wire is inserted. A method for manufacturing an electric wire connection member, characterized by comprising the above.

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