Aluminum terminals

Abstract

To provide an aluminum-based terminal capable of suppressing a temperature rise amount during repeated electrification.SOLUTION: An aluminum-based terminal comprises: a lead wire connection part connected with a lead wire; and a tabular connection part which includes a penetration hole penetrating from a first principal surface and a second principal surface, the first and second principal surfaces being opposed to each other, and in which a peak point height Sxp representing a differential between a height of load area rate 0% and a height of load area rate 10% on at least one principal surface in contact with a connection member between the first principal surface and the second principal surface is 0.30 μm or more and 40.00 μm or less.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to an aluminum-based terminal. [Background technology]

[0002] Copper-based conductors and copper-based terminals are typically used for power distribution cables. In recent years, aluminum-based conductors have also been used to reduce weight. Aluminum-based terminals are also sometimes used to connect the terminals of aluminum-based conductors. An aluminum-based conductor cable with aluminum-based terminals attached to an aluminum-based conductor is fastened to a connecting member using bolts or the like to create an electrical circuit and allow current to flow.

[0003] For example, Patent Document 1 describes that in an electrical connection member made of 6101-T6 aluminum alloy used for electrical connection by mechanical fastening with copper fastened members, the arithmetic mean roughness Ra and mean length RSm at the contact surface with the fastened members satisfy 21≦RSm−21×ln(Ra)≦38 (Ra is less than 10 μm, RSm is less than 100 μm). Patent Document 1 describes that in an electrical connection member made of an aluminum alloy used for electrical connection by mechanical fastening, when the arithmetic mean roughness Ra and mean length RSm at the contact surface with the fastened members satisfy a predetermined relationship, the contact resistance (electrical contact resistance) at the contact surface with the fastened members is reduced.

[0004] However, Patent Document 1 does not mention and is unclear as to whether the electrical connection member can maintain low contact resistance under usage conditions in which current is repeatedly passed over a long period of time after fastening to the fastened members, or whether heat generation in the electrical connection member can be suppressed under such usage conditions. Therefore, when the electrical connection member of Patent Document 1 is applied to a terminal, the temperature change of the terminal due to repeated current passing can cause mechanical misalignment between the terminal and the connection member due to thermal expansion of the terminal, or stress relaxation in the terminal, increasing the contact resistance between the terminal and the connection member, which can result in heat generation or, in the worst case, fire. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6193070 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present disclosure is to provide an aluminum-based terminal that can suppress the amount of temperature rise during repeated current application. [Means for solving the problem]

[0007] [1] An aluminum-based terminal comprising: a conductor connection portion that connects to a conductor; and a plate-shaped connection portion that has a through hole that penetrates from the opposing first principal surface to the second principal surface, and at least one of the first principal surface and the second principal surface that comes into contact with a connecting member has a pole height Sxp that represents the difference between the height at an area load ratio of 0% and the height at an area load ratio of 10% of 0.30 μm or more and 40.00 μm or less. [2] The aluminum-based terminal according to [1] above, having a plating layer on the main surface that contacts the connection member, and a pole height Sxp representing the difference between the height of the plating layer at an area load ratio of 0% and the height at an area load ratio of 10% is 0.30 μm or more and 40.00 μm or less. [3] The aluminum-based terminal according to [2] above, wherein the plating layer is Sn, Ni, Ni-P or Cu. [4] The aluminum-based terminal according to any one of [1] to [3] above, wherein the plate-shaped connecting portion has a 0.2% yield strength of 35 MPa or more and 150 MPa or less when compressed in the thickness direction. [5] In a cross section of the plate-like connecting part along a tangent line on the opposite side of the conductor connection part in the through hole, a line segment connecting both end portions A and B of the first main surface with a straight line is defined as a line segment AB, a midpoint of the line segment AB is defined as a midpoint P, an intersection point between a line L1 that is perpendicular to the line segment AB and passes through the midpoint P and the first main surface is defined as an intersection point R, a line segment connecting the end portion A and the intersection point R is defined as a line segment AR, a line segment connecting both end portions C and D of the second main surface with a straight line is defined as a line segment CD, and The aluminum-based terminal according to any one of the above [1] to [4], wherein, when the midpoint of the line segment CD is defined as midpoint Q, the intersection point between a straight line L2 that is perpendicular to the line segment CD and passes through the midpoint Q and the second main surface is defined as intersection S, and a line segment CS is defined as a line segment connecting the end portion C and the intersection point S, at least one of an angle α1 between the line segment AB and the line segment AR and an angle α2 between the line segment CD and the line segment CS is 0.1 degrees or more and 5.0 degrees or less. [Effects of the Invention]

[0008] According to the present disclosure, it is possible to provide an aluminum-based terminal that can suppress the amount of temperature rise during repeated current application. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a perspective view showing an example of a main configuration of an aluminum-based terminal according to an embodiment. [Figure 2] FIG. 2 is a cross-sectional view taken along line AA in FIG. [Figure 3] FIG. 3 is a perspective view showing an example of an electric wire with an aluminum-based terminal in which the aluminum-based terminal and the electric wire according to the embodiment are crimped together. [Figure 4] FIG. 4 is a schematic diagram for explaining the pole height Sxp of the plate-shaped connecting portion that constitutes the aluminum-based terminal of the embodiment, and is a cross-sectional view showing an example of a main surface of the plate-shaped connecting portion. [Figure 5] FIG. 5 is a schematic diagram for explaining the pole height Sxp of the plate-like connecting portion that constitutes the aluminum-based terminal of the embodiment, and is a diagram showing an example of a load curve. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, a detailed description will be given based on an embodiment.

[0011] As a result of extensive research, the inventors have found that by appropriately controlling the pole height Sxp of the main surface of the plate-shaped connecting portion that comes into contact with the connecting member, it is possible to suppress the amount of temperature rise in the aluminum-based terminal during repeated current flow, even when the main surface having the appropriately controlled pole height Sxp is connected to the connecting member as the contact surface, and have completed the present disclosure based on this finding.

[0012] The aluminum-based terminal of the embodiment includes a conductor connection portion that connects to a conductor wire, and a plate-like connection portion that has a through hole that penetrates from the opposing first principal surface to the second principal surface, and at least one of the first and second principal surfaces that comes into contact with the connecting member has a pole height Sxp that represents the difference between the height at an area load ratio of 0% and the height at an area load ratio of 10% of 0.30 μm or more and 40.00 μm or less.

[0013] Fig. 1 is a perspective view showing an example of a main configuration of an aluminum-based terminal of an embodiment. Fig. 2 is a cross-sectional view taken along line AA in Fig. 1. Fig. 3 is a perspective view showing an example of an aluminum-based terminal-attached electric wire in which the aluminum-based terminal of an embodiment and an electric wire are crimped. For convenience, a plating layer 23 is omitted from Fig. 2.

[0014] As shown in Fig. 1, the aluminum-based terminal 1 includes a conductor connection portion 10 and a plate-shaped connection portion 20. The aluminum-based terminal 1 is made of an aluminum-based material including pure aluminum and aluminum alloys. For example, the aluminum-based terminal 1 is made of A1070.

[0015] The conductor connection portion 10 constituting the aluminum-based terminal 1 is connected to a conductor 51 as shown in Fig. 3. The conductor 51 is composed of at least one or more elemental wires 51a, for example as shown in Fig. 3. The conductor 51 may be a stranded wire in which a plurality of elemental wires 51a are twisted together as shown in Fig. 3, a bundled wire in which a plurality of elemental wires 51a are bundled, or a single elemental wire 51a. The conductor 51 and the elemental wire 51a are preferably made of an aluminum-based material including pure aluminum and an aluminum alloy, or a copper-based material including pure copper and a copper alloy, and more preferably made of an aluminum-based material.

[0016] An insulating coating portion 52 may be provided on the outer periphery of the conductor 51, and a sheath 53 may be provided on the outer periphery of the insulating coating portion 52.

[0017] In Figure 3, at one end of an electric wire 50 having a conductor 51, an insulating coating portion 52, and a sheath 53, the insulating coating portion 52 covering the outer periphery of the conductor 51 and the sheath 53 covering the outer periphery of the insulating coating portion 52 are stripped from the electric wire 50, exposing the conductor 51.

[0018] As shown in Fig. 3, one end of the aluminum-based terminal 1 is provided with a tubular conductor connection portion 10 into which the conductor 51 exposed at one end of the electric wire 50 is inserted. When the conductor connection portion 10 of the aluminum-based terminal 1 is crimped with the conductor 51 inserted into it, a crimped portion 11 is formed, and an electric wire with an aluminum-based terminal is obtained. The conductor connection portion 10 is crimped to the conductor 51 via the crimped portion 11, and is electrically connected to the conductor 51. At the crimped portion 11, the conductor 51 of the electric wire 50 is crimped to the conductor connection portion 10 of the aluminum-based terminal 1.

[0019] Here, an example is shown in which the conductor connection part 10 has a closed tubular shape, but the shape of the conductor connection part 10 is not limited as long as the conductor connection part 10 can be crimped to the conductor 51. The conductor connection part 10 may have, for example, an open tubular shape.

[0020] 1 and 3, a plate-shaped connecting portion 20 is provided on the other end side of the aluminum-based terminal 1. The plate-shaped connecting portion 20 has a through-hole 22 that penetrates from the first main surface 21a to the second main surface 21b, which are opposed to each other. A fastening member (not shown), such as a bolt, is inserted into the through-hole 22 of the plate-shaped connecting portion 20 to mechanically and electrically connect the plate-shaped connecting portion 20 of the aluminum-based terminal 1 to a connecting member (not shown) (including the plate-shaped connecting portion 20 of a separate aluminum-based terminal 1, not shown) (not shown), rather than the aluminum-based terminal 1 shown). Because a cylindrical fastening member is inserted into the through-hole 22, it is preferable that the through-hole 22 be circular.

[0021] In the plate-shaped connecting part 20, the pole height Sxp (hereinafter simply referred to as the pole height Sxp) representing the difference between the height at a load area ratio of 0% and the height at a load area ratio of 10% of at least one of the first main surface 21a and the second main surface 21b that contacts the connecting member (not shown) is 0.30 μm or more and 40.00 μm or less.

[0022] Fig. 4 is a schematic diagram for explaining the pole point height Sxp of a plate-shaped connecting part constituting an aluminum-based terminal of an embodiment, and is a cross-sectional view showing an example of a main surface of a plate-shaped connecting part. Fig. 5 is a schematic diagram for explaining the pole point height Sxp of a plate-shaped connecting part constituting an aluminum-based terminal of an embodiment, and is a diagram showing an example of a load curve.

[0023] When the second main surface 21b of the plate-like connecting portion 20 is used as a contact surface to be joined to a joining member (not shown), the inventors consider the relationship between the suppression of the temperature rise of the aluminum-based terminal 1 during repeated current application and the surface shape of the second main surface 21b as follows. Also, for convenience, the plating layer 23 is omitted.

[0024] When the second main surface 21b of the plate-shaped connecting portion 20 is viewed microscopically, as shown in FIG. 4, there are minute irregularities on the second main surface 21b. When joining the plate-shaped connecting portion 20 of the aluminum-based terminal 1 to a connecting member (not shown) to pass electricity, it is necessary to destroy the oxide films present on the surfaces of the plate-shaped connecting portion 20 and the connecting member to bring the metals of the plate-shaped connecting portion 20 and the connecting member into contact. This is because the oxide film is insulating or has very low conductivity. To destroy the oxide film, it is necessary to apply a certain amount of load to bring the plate-shaped connecting portion 20 and the connecting member into contact. Once the oxide film is destroyed and the metals come into contact, the contact resistance between the plate-shaped connecting portion 20 and the connecting member is reduced, ensuring electrical continuity between the plate-shaped connecting portion 20 and the connecting member.

[0025] It is believed that material deformation affects such oxide film breakdown and contact resistance, and further microscopic observation has revealed that the amount of deformation of the peaks on the second main surface 21b that first come into contact with the connecting member is related. When the peaks on the second main surface 21b deform, the oxide film is broken, exposing the metal, reducing contact resistance and ensuring electrical continuity between the plate-shaped connecting part 20 and the connecting member. The deformability of an oxide film differs from that of a metal. Therefore, when the peaks are deformed to a large extent, a large shift occurs corresponding to that amount of deformation, making the oxide film more likely to be broken and ensuring electrical continuity. On the other hand, when the peaks are deformed to a small extent, the shift corresponding to that amount of deformation is small, making the oxide film less likely to be broken and electrical continuity less likely to be achieved.

[0026] Therefore, controlling the amount of deformation of the peaks is important for destroying the oxide film and reducing contact resistance, and we have devised the extreme point height Sxp as a parameter representing the amount of deformation of the peaks. This is expressed as the distance from the peak of the peak to a certain depth. We have found that the certain depth can be expressed as the depth x at which the cross-sectional area of ​​various peaks, when cut vertically at a position of a certain depth x from the peak of the highest peak in the measurement region, becomes 10% of the total area of ​​the measurement region. In this embodiment, as shown in Figure 5, the extreme point height Sxp is defined as the difference between the height at which the peak of the peak is at a material load ratio of 0% and the height at which the material load ratio is at a depth at which the cross-sectional area of ​​the peak is 10% of the total area of ​​the measurement region.

[0027] If the pole point height Sxp of the second main surface 21b is less than 0.30 μm, the deformation of the ridges will be insufficient, resulting in high contact resistance and a large temperature rise during repeated energization. Furthermore, if the pole point height Sxp of the second main surface 21b is greater than 40.00 μm, uneven plating may occur in the plated surface layer on the second main surface 21b side, resulting in high contact resistance and a large temperature rise during repeated energization. Furthermore, wear powder is likely to be generated, and the wear powder may get between the second main surface 21b and the connecting member, increasing contact resistance and a large temperature rise during repeated energization.

[0028] The above describes a case where electricity flows by contacting the second main surface 21b of the aluminum-based terminal 1 with a connecting member (not shown). When the first main surface 21a of the aluminum-based terminal 1 contacts the connecting member, the pole height Sxp of the first main surface 21a may be controlled in the same way as the second main surface 21b.

[0029] From the above, the lower limit of the pole height Sxp of at least one of the first main surface 21a and the second main surface 21b that comes into contact with the connecting member is 0.30 μm or more, preferably 2.20 μm or more, and more preferably 10.00 μm or more, and the upper limit is 40.00 μm or less. It is even more preferable that both the first main surface 21a and the second main surface 21b are within the above ranges.

[0030] Here, a typical index representing surface roughness is the arithmetic mean height Sa. The arithmetic mean height Sa is an index expressed as the average of the peaks and valleys on a surface. However, in this embodiment, the amount of deformation of the peaks that first come into contact with the connecting member is thought to have a significant effect on the contact resistance, so the extreme point height Sxp is used instead of the arithmetic mean height Sa. As an example, on a surface with a grid-like pattern, such as that of tiles glued together, the area of ​​the peaks on the flat surface has a significant effect on the contact resistance. Therefore, evaluating the surface using the extreme point height Sxp will appropriately represent the peaks, but evaluating the surface using the arithmetic mean height Sa will result in an index that also includes the valleys (grooves). Therefore, using the arithmetic mean height Sa in this embodiment is not appropriate.

[0031] Furthermore, the plate-shaped connecting part 20 has a plating layer 23 on the main surface that contacts the connecting member, and the extreme height Sxp, which represents the difference between the height of the plating layer 23 at a load area ratio of 0% and the height at a load area ratio of 10%, is preferably 0.30 μm or more and 40.00 μm or less.

[0032] The plating layer 23 is provided on one of the first and second main surfaces 21a and 21b, whichever is in contact with a connecting member. Similar to the first and second main surfaces 21a and 21b, an oxide film is also formed on the surface of the plating layer 23. When the plating layer 23 is used as a contact surface to join to a connecting member (not shown), the considerations regarding the second main surface 21b described above can also be applied to the plating layer 23 in terms of reducing contact resistance by destroying the oxide film, with regard to the relationship between the suppression of temperature rise in the aluminum-based terminal 1 during repeated current application and the surface shape of the plating layer 23. Therefore, the lower limit of the pole height Sxp of the plating layer 23 is preferably 0.30 μm or more, more preferably 2.20 μm or more, and even more preferably 10.00 μm or more, and the upper limit is preferably 40.00 μm or less.

[0033] First, the surface is observed using a laser microscope to determine the above-mentioned pole height Sxp. The highest and lowest points of the pole height are set to 0% and 10% of the observation area, respectively, and the pole height is calculated. This measurement is performed multiple times so that the observation areas do not overlap. These multiple pole height values ​​are then averaged to obtain the pole height Sxp.

[0034] Furthermore, the plating layer 23 is preferably made of Sn, Ni, Ni-P, or Cu. The plating layer 23 made of Sn is commonly used for electrical contacts and is soft, making it easy to destroy oxide films and reducing contact resistance. The plating layer 23 made of Ni or Ni-P is a hard material, improving durability. The plating layer 23 made of Cu exhibits intermediate properties between Sn and Ni plating layers, achieving a good balance between electrical resistivity and durability. Thus, the type of plating for the plating layer 23 can be appropriately selected depending on the application of the aluminum-based terminal 1. When the plating layer 23 made of these plating types is connected to a connecting member, it is believed that, when viewed microscopically, the ridges deform, destroying the oxide film and reducing contact resistance.

[0035] Furthermore, the 0.2% yield strength (hereinafter simply referred to as 0.2% yield strength) of the plate-shaped connecting part 20 when compressed in the thickness direction is preferably 35 MPa or more and 150 MPa or less. The thickness direction of the plate-shaped connecting part 20 is the direction of a straight line connecting the first main surface 21a and the second main surface 21b.

[0036] The amount of deformation of the ridges present on the surface of the plate-shaped connecting part 20 depends on the crushability of the plate-shaped connecting part 20. Therefore, the 0.2% yield strength of the plate-shaped connecting part 20 obtained when the plate-shaped connecting part 20 is compressed in the thickness direction is defined as an index representing the crushability of the plate-shaped connecting part 20. If the 0.2% yield strength is less than 35 MPa, the plate-shaped connecting part 20 is too soft and may deform or break during or after installation, potentially preventing the installation as designed. On the other hand, if the 0.2% yield strength is greater than 150 MPa, the oxide film is difficult to break, making it difficult to ensure sufficient conductivity and resulting in a large temperature rise during repeated current application. For these reasons, the lower limit of the 0.2% yield strength is preferably 35 MPa or more, and the upper limit is preferably 150 MPa or less, and more preferably 130 MPa or less.

[0037] Regarding the angles α1 and α2 described in detail below, the 0.2% yield strength of the plate-like connecting part 20 where the angles α1 and α2 are 0 degrees is obtained by the offset method described in JIS Z 2241 from a stress-strain curve obtained by performing a compression test in the thickness direction of the plate-like connecting part 20 on a sample obtained by cutting out the plate-like connecting part 20. The sample is cut out so that its thickness is the same as that of the plate-like connecting part 20. Furthermore, the 0.2% yield strength of the plate-like connecting part 20 where at least one of the angles α1 and α2 is other than 0 degrees cannot be accurately measured because the contact area with the sample changes during the compression test. Therefore, the 0.2% yield strength is measured for the plate-like connecting part 20 where the angles α1 and α2 are 0 degrees.

[0038] 2 is a cross-sectional view taken along line AA in FIG. 1, and is a schematic diagram for explaining the angle α1 formed between line segment AB and line segment AR and the angle α2 formed between line segment CD and line segment CS in the cross section of plate-like connecting part 20. The cross section shown in FIG. 2 is a cross-section seen from the conductor connection part 10 side, and is a cross-section of a portion that does not include through-hole 22. For convenience, plating layer 23 is omitted from FIG. 2.

[0039] As shown in FIGS. 1 and 2, in a cross section of the plate-like connecting part 20 taken along a tangent line of the through-hole 22 on the opposite side to the conductor connection part 10, a line segment connecting both end parts A and B of the first main surface 21a with a straight line is defined as a line segment AB, the midpoint of the line segment AB is defined as a midpoint P, the intersection of a line L1 that is perpendicular to the line segment AB and passes through the midpoint P with the first main surface 21a is defined as an intersection point R, a line segment connecting the end part A with the intersection point R is defined as a line segment AR, and both end parts A and B of the second main surface 21b are defined as a line segment AB. If the line segment connecting ends C and D is defined as line segment CD, the midpoint of line segment CD is defined as midpoint Q, the intersection of line L2 that is perpendicular to line segment CD and passes through midpoint Q with second main surface 21b is defined as intersection S, and the line segment connecting end C with intersection S is defined as line segment CS, then it is preferable that at least one of angle α1 between line segment AB and line segment AR and angle α2 between line segment CD and line segment CS be 0.1 degrees or more and 5.0 degrees or less. Line segment AB, line segment L1, line segment AR, line segment CD, line segment L2, and line segment CS shown in Figure 2 are imaginary lines.

[0040] Here, when the first main surface 21a of the plate-shaped connecting part 20 is brought into contact with a connecting member, if the contact area between the first main surface 21a and the connecting member is reduced and the load per unit area is increased, the load can be applied efficiently, allowing the peaks to deform more greatly, the oxide film to be further destroyed, and the contact resistance to be further reduced. Also, when the second main surface 21b of the plate-shaped connecting part 20 is brought into contact with a connecting member, similar to the first main surface 21a, if the contact area between the second main surface 21b and the connecting member is reduced and the load per unit area is increased, the load can be applied efficiently, allowing the peaks to deform more greatly, the oxide film to be further destroyed, and the contact resistance to be further reduced.

[0041] Therefore, when at least one of the angles α1 and α2 is 0.1 degrees or greater, the area of ​​contact with the connecting member can be reduced around the through hole 22, where the plate-shaped connecting portion 20 is most heavily loaded, and contact resistance can be further reduced. Furthermore, when at least one of the angles α1 and α2 exceeds 5.0 degrees, the gap between the plate-shaped connecting portion 20 and the connecting member becomes large, which may result in the accumulation of wear powder and dust generated when the aluminum-based terminal 1 is fastened to the connecting member by the bolt. For this reason, the lower limit of at least one of the angles α1 and α2 is preferably 0.1 degrees or greater, more preferably 1.0 degrees or greater, and the upper limit is preferably 5.0 degrees or less. More preferably, both the angles α1 and α2 are within the above ranges.

[0042] 1, the tangent line of through hole 22 on the side opposite conductor connection portion 10 does not refer to the tangent line on the conductor connection portion 10 side when viewed from the center of through hole 22, but to the tangent line on the side opposite conductor connection portion 10. The cross section of plate-like connection portion 20 taken along the tangent line of through hole 22 on the side opposite conductor connection portion 10 is the cross section viewed from the conductor connection portion 10 side, and is the cross section of the portion that does not include through hole 22.

[0043] 2 shows an example in which the first main surface 21a has a concave shape, but the first main surface 21a may have a convex shape. Similarly, although the example in which the second main surface 21b has a convex shape is shown, the second main surface 21b may have a concave shape.

[0044] Next, a method for manufacturing the aluminum-based terminal 1 will be described.

[0045] First, in the first forging step, the center of a round bar made of an aluminum-based material is compressed by forging to form the conductor wire connection portion 10.

[0046] The first heat treatment step, which is carried out after the first forging step, is carried out for the purpose of reducing deformation resistance when the conductor connection part 10 and the conductor are crimped. The first heat treatment step is not particularly limited, but is preferably carried out at 300°C to 450°C for 1 to 3 hours, as this is an industrially stable heat treatment. For example, heat treatment is carried out at 300°C for 1 hour.

[0047] In the second forging step carried out after the first heat treatment step, the end opposite the conductor wire connection portion 10 is forged into a die and compressed to form a plate-like portion.

[0048] In the third forging process performed after the second forging process, the plate-shaped portion is forged using a die to change the pole height Sxp of the main surface of the plate-shaped portion. Two dies are placed to sandwich the plate-shaped portion, and the plate-shaped portion is pressed to change the surface condition of the plate-shaped portion. In this way, the plate-shaped connecting portion 20 is formed. The inner surface of the die is sandblasted. Furthermore, when forming a plate-shaped connecting portion 20 in which at least one of the formed angles α1 and α2 is other than 0 degrees, a die that can be curved concentrically toward the center of the plate-shaped portion is used.

[0049] In the punching step carried out after the third forging step, through holes 22 are formed in the plate-shaped connecting portions 20 by punching.

[0050] In the deburring process carried out after the punching process, chamfering is performed by lathe processing to remove burrs around the through-hole 22 generated in the punching process.

[0051] The second heat treatment process, which is carried out after the deburring process, is carried out for the purpose of increasing the amount of deformation at the plate-like connecting portion 20 when the bolt is fastened, making it easier to destroy the oxide film. The second heat treatment process is carried out at a temperature of 300°C to 600°C for 1 hour to 3 hours. The second heat treatment process is an optional process.

[0052] If the plate-like connecting portion has a plating layer 23, a plating step is performed after the second heat treatment step. As an example, Ni-P plating is applied using a double zincate treatment, and then Sn, Ni, or Cu plating is applied to the outer surface. To improve adhesion, a thin Cu plating layer may be applied to the outer surface adjacent to the Ni-P plating layer. In this way, the aluminum-based terminal 1 is obtained.

[0053] Next, a method for manufacturing the electric wire with aluminum terminal 100 in which the aluminum terminal 1 and the electric wire 50 are crimped will be described.

[0054] First, in the compound insertion process, a compound material is applied to the inside of the conductor connection portion 10 to improve adhesion between the conductor connection portion 10 and the conductor 51. The compound material is mainly composed of mineral oil and zinc powder and is used to ensure a good connection between the conductor connection portion 10 and the conductor 51. When the compound material is provided inside the conductor connection portion 10, it plays a role in ensuring good conductivity of the aluminum-based terminal-attached wire 100, destroying the oxide coatings on the conductor connection portion 10 and the conductor 51, and waterproofing the crimped portion 11.

[0055] In the crimping process carried out after the compound insertion process, the conductor 51 is inserted into the conductor connection portion 10, and a crimping tool is used to apply force to the conductor connection portion 10 from one direction to crimp the conductor connection portion 10 and the conductor 51 together, forming the crimped portion 11. The larger the depression of the crimped portion 11, in other words, the greater the pressing force during crimping, the stronger the bond between the conductor connection portion 10 and the conductor 51. In this way, an electric wire with an aluminum-based terminal 100 is obtained.

[0056] Such an aluminum-based terminal 1 is suitable for use as a terminal connecting member used when connecting electric wires together.

[0057] According to the embodiment described above, by appropriately controlling the pole height Sxp of the main surface of the plate-shaped connecting portion that contacts the connecting member within a predetermined range, the amount of temperature rise in the aluminum-based terminal can be suppressed even when the plate-shaped connecting portion is connected to the connecting member and current is repeatedly applied, so that the aluminum-based terminal can be used safely and securely without catching fire even when current is repeatedly applied.

[0058] Although the embodiments have been described above, the present invention is not limited to the above embodiments, but includes all aspects encompassed by the concept and scope of the claims of the present disclosure, and can be modified in various ways within the scope of the present disclosure. [Example]

[0059] Next, examples and comparative examples will be described, but the present invention is not limited to these examples.

[0060] (Examples 1 to 36, Comparative Examples 1 to 8) The center of a round bar made of an aluminum-based material having the components shown in Tables 1 and 2 was compressed by forging to form a conductor connection portion.

[0061] Subsequently, in order to reduce the deformation resistance when the conductor connection portion and the conductor are crimped, a first heat treatment step was carried out at 300° C. for 1 hour.

[0062] Next, the end opposite the conductor connection portion was forged into a die and compressed to form a plate-like portion.

[0063] Next, the plate-shaped portion was forged using a die to set the pole height Sxp of the main surface of the plate-shaped portion to the values ​​in Tables 1 and 2. In the forging, two dies were placed to sandwich the plate-shaped portion, and the plate-shaped portion was pressed to change the surface condition of the plate-shaped portion. In this way, the plate-shaped connecting portion was formed.

[0064] The inner surface of the mold used here was sandblasted. Sandblasting was performed in accordance with JIS R6001 using abrasive particles of F20, F40, F60, F80, F100, F220, F400, F600, and F1200. However, due to the large variation in the pole height Sxp across the entire machined surface, the distance from the mold and the irradiation time of the abrasive particles were increased to ensure uniformity over a wide area of ​​the machined surface. In Comparative Examples 1 and 3-8, the normal molds without sandblasting were used, and the inner surface of the mold was finished using #4000 abrasive paper. Furthermore, in Examples 11-16, 19-24, 26, 28, 30-31, 33-34, and 36, a mold capable of concentrically curving toward the center of the plate-shaped portion was used to form a plate-shaped connecting portion in which at least one of the angles α1 and α2 was other than 0 degrees.

[0065] Subsequently, a through hole was drilled in the plate-like connecting portion, and then the plate-like connecting portion was chamfered by lathe processing.

[0066] Next, in Examples 9 to 10, 16, and 18, in order to increase the amount of deformation at the plate-like connecting portion when the bolt is fastened and make it easier to destroy the oxide film, a second heat treatment step was performed in an atmospheric heating furnace under the conditions shown in Table 1.

[0067] Subsequently, in Examples 20 to 36 and Comparative Examples 5 to 8, a plating layer having a thickness of 5 μm as shown in Table 2 was formed on the plate-like connecting portion.

[0068] In this way, an aluminum-based terminal was obtained.

[0069] Next, a compound material (Compound A, manufactured by Furukawa Power Systems Co., Ltd.) was applied to the inside of the conductor connection portion. Next, an aluminum-based conductor wire was inserted into the conductor connection portion, and a crimping tool was used to apply force to the conductor connection portion from one direction to crimp the conductor connection portion and the aluminum-based conductor wire, thereby forming a crimped portion. In this way, an aluminum-based electric wire with an aluminum-based terminal was obtained.

[0070] [Measurement and Evaluation] The aluminum-based electric wires with aluminum-based terminals obtained in the above Examples and Comparative Examples were subjected to the following measurements and evaluations. The results are shown in Tables 1 and 2.

[0071] [1] Pole height Sxp Using a laser microscope (VK-X1000, manufactured by Keyence), the surface of the second main surface in contact with the connecting member was observed in an observation area of ​​210 μm × 280 μm. The highest and lowest points of the polar height were set to 0% and 10%, respectively, for the observed area, and the polar height was calculated. This measurement was performed three times (n = 3) so that the observation areas did not overlap, and the average of n3 was calculated.

[0072] [2] 0.2% yield strength Rectangular samples measuring 10 mm wide and 10 mm deep were cut from the plate-like joints, and compression tests were performed twice (n=2) in the thickness direction of the samples using a Shimadzu Corporation autograph, AG-100KND model. The 0.2% yield strength was determined from the stress-strain curves obtained from the compression tests using the offset method specified in JIS Z 2241, and the average n2 was calculated. The sample thickness was 8.3 mm, the same as the thickness of the plate-like joints. For plate-like joints in which at least one of the angles α1 and α2 was non-zero, such as in Examples 11-16, 19-24, 26, 28, 30-31, 33-34, and 36, the 0.2% yield strength was measured for plate-like joints in which the angles α1 and α2 were 0 degrees.

[0073] [3] Angle α1 and Angle α2 After filling the plate-shaped connection part with resin, the plate-shaped connection part was cut along the tangent line of the through-hole on the opposite side to the conductor connection part. The cut surface of the plate-shaped connection part was then polished and observed under a microscope to determine the angles α1 and α2.

[0074] [4] Heat cycle test To evaluate the amount of temperature rise during repeated current application, a heat cycle test was conducted with reference to the heat cycle test described in "JIS C 2810 General Rules for Electric Wire Connectors for Indoor Wiring - Non-Separable Type." Multiple aluminum-based electric wires with aluminum-based terminals, each 2 m or longer, obtained in each Example or Comparative Example were prepared. The second principal surfaces of the aluminum-based terminals were connected in series via a terminal block, and a current value was set so that the temperature of the aluminum-based electric wire reached 105°C. A slit was made in the insulating coating of any aluminum-based electric wire at its center, and a thermocouple was inserted so that it contacted the conductor of the aluminum-based electric wire to measure the temperature of the aluminum-based electric wire. A thermocouple was also soldered to the plate-shaped connection portion of the aluminum-based terminal to measure the temperature of the aluminum-based terminal. A cycle consisted of applying current at a set current value for one hour, followed by stopping the current for one hour. The temperature rise (°C) of the aluminum-based terminal one hour after the 500th cycle was measured, compared to the temperature of the aluminum-based terminal one hour after the 25th cycle. The smaller the temperature rise, the better, in terms of being able to suppress heat generation in aluminum-based electric wires with aluminum-based terminals. For aluminum-based terminals without a plating layer, if the temperature rise is less than 20°C, it is considered to have the effect of suppressing the temperature rise and is therefore considered to have passed the test. For aluminum-based terminals with a plating layer, although the plating process adds costs, if the temperature rise is less than 8°C, it is considered to have an even greater effect of suppressing the temperature rise and is therefore considered to have passed the test.

[0075] [Table 1]

[0076] [Table 2]

[0077] As shown in Table 1, in Examples 1 to 19, the pole height Sxp of the main surface (the second main surface in all of these Examples) of the plate-shaped connecting portion that comes into contact with the connecting member was within the range of 0.30 μm or more and 40.00 μm or less, and the temperature rise after the heat cycle test was less than 20° C., whereas in Comparative Examples 1 to 4, the pole height Sxp of the main surface (the second main surface in all of these Comparative Examples) that comes into contact with the connecting member of the plate-shaped connecting portion was outside the above range, and the temperature rise after the heat cycle test was 20° C. or more. Furthermore, in Examples 11 to 16 and 19, at least one of the formed angles α1 and α2 was 0.1 degrees or more and 5.0 degrees or less, and the temperature rise after the heat cycle test was further suppressed. In addition, in Comparative Example 4, an aluminum-based terminal was manufactured in the same manner as in Comparative Example 3, except that stripe-shaped grooves were finally formed on the surface of the plate-shaped connection portion using a lathe.The arithmetic mean height Sa of this surface was 70 μm, but the pole height Sxp was 0.27 μm because it was not related to the groove portion, and the temperature rise was 20°C or more.

[0078] Furthermore, as shown in Table 2, in Examples 20 to 36 and Comparative Examples 5 to 8, which included a plating layer, although the manufacturing costs increased due to the additional plating process, the temperature rise after the heat cycle test was reduced compared to Examples not including a plating layer. Furthermore, in Examples 20 to 36, the pole height Sxp of the main surface (second main surface) of the plate-shaped connecting portion that contacts the connection member was within the range of 0.30 μm to 40.00 μm, and the temperature rise after the heat cycle test was less than 8°C, whereas in Comparative Examples 5 to 8, the pole height Sxp of the main surface (second main surface) of the plate-shaped connecting portion that contacts the connection member was outside the above range, and the temperature rise after the heat cycle test was 8°C or more. Furthermore, in Examples 20 to 24, 26, 28, 30 to 31, 33 to 34, and 36, at least one of the formed angles α1 and α2 was within the range of 0.1 degrees to 5.0 degrees, and the temperature rise after the heat cycle test was further reduced. [Explanation of symbols]

[0079] 1 Aluminum terminal 10 Conductor connection 11 Crimping section 20 Plate-shaped connection part 21a 1st main surface 21b 2nd principal surface 22 through holes 23 plating layer 50 Electric wire 51 Conductor 51a Bare wire 52 Insulation coating 53 Sheath 100 Aluminum terminal-attached wire

Claims

1. a conductor connection portion for connecting to the conductor; a plate-like connecting part having a through hole penetrating from a first main surface to a second main surface facing each other, and at least one of the first main surface and the second main surface that comes into contact with a connecting member has a pole height Sxp that represents a difference between a height at an area load ratio of 0% and a height at an area load ratio of 10% of 0.30 μm or more and 40.00 μm or less; An aluminum-based terminal comprising:

2. a plating layer on the main surface that contacts the connection member; 2. The aluminum-based terminal according to claim 1, wherein a pole height Sxp representing a difference between a height at an area load ratio of 0% and a height at an area load ratio of 10% of the plating layer is 0.30 μm or more and 40.00 μm or less.

3. 3. The aluminum-based terminal according to claim 2, wherein the plating layer is made of Sn, Ni, Ni--P or Cu.

4. The aluminum-based terminal according to any one of claims 1 to 3, wherein the plate-shaped connecting portion has a 0.2% yield strength of 35 MPa or more and 150 MPa or less when compressed in the thickness direction.

5. In a cross section of the plate-shaped connection portion taken along a tangent line of the through hole on the opposite side to the conductor connection portion, A line segment connecting both end portions A and B of the first main surface with a straight line is defined as a line segment AB, a midpoint of the line segment AB is defined as a midpoint P, an intersection point between a line L1 that is perpendicular to the line segment AB and passes through the midpoint P and the first main surface is defined as an intersection point R, and a line segment connecting the end portion A and the intersection point R is defined as a line segment AR, A line segment CD connects both end portions C, D of the second main surface, a midpoint Q of the line segment CD, an intersection S of a line L2 that is perpendicular to the line segment CD and passes through the midpoint Q with the second main surface, and a line segment CS that connects the end portion C with the intersection S. The aluminum-based terminal according to any one of claims 1 to 4, wherein at least one of the angle α1 between the line segment AB and the line segment AR and the angle α2 between the line segment CD and the line segment CS is 0.1 degrees or more and 5.0 degrees or less.

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