terminal

Abstract

To provide a terminal capable of suppressing a temperature rise in a case where electrification is repeated for a long time.SOLUTION: A terminal 1 consists of aluminum or an aluminum alloy and comprises a lead wire connection part 10 and a tabular part 20 which includes a first principal surface 21a and a second principal surface 21b opposed to the first principal surface 21a and in which a penetration hole 22 penetrating the first principal surface 21a and the second principal surface 21b is formed. In crystal orientation analysis performed in a first cross section region including the first principal surface 21a and a second cross section region including the second principal surface 21b in four cross section regions obtained by equally dividing a thickness of the tabular part 20 into four in a view on a predetermined cross section by an annular portion 20a of the tabular part 20 defined by the penetration hole 22 and a virtual concentric circle R having a diameter 1.5 times as large as a hole diameter of the penetration hole 22, both ratios of measurement points where KAM values in the first cross section region and the second cross section region are within a range of 1° or more to less than 4° are 70% or more with respect to all the measurement points.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a terminal made of aluminum or an aluminum alloy. [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. By fastening an aluminum-based conductor cable with aluminum-based terminals, in which aluminum-based terminals are attached to an aluminum-based conductor, to a connecting member using bolts or the like, an electrical circuit can be formed and current can flow.

[0003] Of these, Patent Document 1, for example, describes an aluminum-based terminal that 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 a load area ratio of 0% and the height at a load area ratio of 10% of 0.30 μm to 40.00 μm.By adopting this configuration, it is possible to provide an aluminum-based terminal that can suppress the amount of temperature rise during repeated current flow by appropriately controlling the pole height Sxp of the principal surface of the plate-like connection portion that comes into contact with the connecting member within a predetermined range. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2023-53682 Summary of the Invention [Problem to be solved by the invention]

[0005] The fastening parts between the aluminum-based terminals and the connecting members may generate heat due to temperature changes in the aluminum-based terminals caused by repeated current flow, which may cause stress relaxation in the aluminum-based terminals and increase the contact resistance between the aluminum-based terminals and the connecting members, and in the worst case scenario, this may lead to a fire.

[0006] In this regard, the aluminum-based terminal described in Patent Document 1 suppresses the amount of temperature rise when electricity is repeatedly passed through it by controlling the surface shape of the main surface that contacts the connecting member. However, sufficient consideration has not been given to the characteristics of the aluminum-based conductor that constitutes the plate-shaped portion (plate-shaped connecting portion) that has the main surface that contacts the connecting member, particularly in terms of controlling the crystal orientation, and there is room for improvement in terms of suppressing the amount of temperature rise when electricity is repeatedly passed through it for a longer period of time, particularly taking this viewpoint into consideration.

[0007] Therefore, the present invention has been made in consideration of the above problems, and aims to provide a terminal that can control the characteristics of the aluminum-based conductor that makes up the plate-shaped portion, thereby suppressing the amount of temperature rise when electricity is repeatedly passed through it over a long period of time. [Means for solving the problem]

[0008] The inventors have thoroughly studied the properties of the aluminum-based conductor that makes up the plate-like portion, and have focused on controlling the crystalline structure of the aluminum-based conductor, more specifically, controlling the KAM value, which represents the difference in crystal orientation between measurement points included in a first cross-sectional area including the first main surface and a second cross-sectional area including the second main surface opposite the first main surface, within the annular portion defined by the through hole of the plate-like portion and a virtual concentric circle having a diameter 1.5 times the diameter of the through hole.They have found that by increasing the proportion of measurement points in both the first and second cross-sectional areas where the KAM values ​​are within a specific range, it is possible to suppress temperature rise when electricity is repeatedly passed through for a long period of time, thereby reducing stress relaxation in the terminal and maintaining low contact resistance, and have completed the present invention.

[0009] That is, the gist of the present invention is as follows. (1) A terminal comprising: a conductor connection portion made of aluminum or an aluminum alloy and connected to a conductor; and a plate-like portion integrally formed with the conductor connection portion, the plate-like portion having a first main surface and a second main surface opposite the first main surface, and a through hole penetrating the first main surface and the second main surface, wherein, in a cross section of the annular portion of the plate-like portion defined by the through hole and imaginary concentric circles having a diameter 1.5 times the diameter of the through hole, when viewed in a cross section cut along an imaginary plane including the central axis of the through hole, the plate-like portion is divided into four equal cross-sectional regions obtained by dividing the plate-like portion into four equal sections, a first cross-sectional region including the first main surface and a second cross-sectional region including the second main surface, and in this cross-sectional region, the proportion of measurement points in which the KAM value is in the range of 1° or more and less than 4° in the first cross-sectional region and the second cross-sectional region is 70% or more of all measurement points. (2) The terminal described in (1) above, wherein in the crystal orientation analysis, the proportion of measurement points in the first cross-sectional area and the second cross-sectional area where the KAM value is in the range of 1° or more and less than 2° is 70% or more of all measurement points in each area. (3) The terminal according to (1) or (2) above, having one or more surface treatment layers selected from the group consisting of a Zn layer, a Sn layer, a Ni layer, a Ni-P layer, and a Cu layer on at least a portion of one or both of the first main surface and the second main surface. [Effects of the Invention]

[0010] According to the present invention, the characteristics of the aluminum-based conductor constituting the plate-shaped portion are controlled, thereby providing a terminal capable of suppressing the amount of temperature rise when current is repeatedly applied over a long period of time. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a perspective view showing an example of the configuration of a terminal according to an embodiment of the present invention. [Figure 2]FIG. 2 is a cross-sectional view of the terminal of FIG. 1 taken along an imaginary plane P including the central axis of the through hole. [Figure 3] FIG. 3 is a perspective view showing an example of a terminal-attached electric wire in which a terminal and an electric wire according to an embodiment of the present invention are crimped together. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, preferred embodiments of the terminal of the present invention will be described in detail.

[0013] Fig. 1 is a perspective view showing an example of the configuration of a terminal according to an embodiment of the present invention. Fig. 2 is a cross-sectional view of the terminal of Fig. 1 cut along an imaginary plane P including the central axis of the through hole. Fig. 3 is a perspective view showing an example of a terminal-attached electric wire in which the terminal according to the embodiment and an electric wire are crimped. For convenience, a surface treatment layer 24 is omitted from Fig. 2.

[0014] The terminal 1 is made of aluminum or an aluminum alloy and includes a conductor connection portion 10 for connection to a conductor wire, and a plate-like portion 20 formed integrally with the conductor connection portion 10, the plate-like portion 20 having a first main surface 21 a and a second main surface 21 b opposed to the first main surface 21 a, and having a through hole 22 penetrating the first main surface 21 a and the second main surface 21 b, and the annular portion 20 a of the plate-like portion 20 defined by the through hole 22 and an imaginary concentric circle R having a diameter 1.5 times the diameter of the through hole 22 is aligned with an imaginary plane including a central axis C of the through hole 22. When viewed from a cross section cut at P, of the four cross-sectional regions obtained by dividing the thickness of the plate-shaped portion 20 into four equal parts, crystal orientation analysis was performed by electron backscatter diffraction (EBSD) on the first cross-sectional region 23a, 23a' including the first main surface 21a and the second cross-sectional region 23b, 23b' including the second main surface 21b. In this analysis, the proportion of measurement points in the first cross-sectional region 23a, 23a' and the second cross-sectional region 23b, 23b' where the KAM value is in the range of 1° or more and less than 4° is 70% or more of all measurement points.

[0015] In the terminal 1 of the present invention, in the annular portion 20a defined by the through hole 22 in the plate-like portion 20 and the imaginary concentric circle R having a diameter 1.5 times the diameter of the through hole 22, the KAM value, which represents the crystal orientation difference between the measurement points included in the first cross-sectional region 23a, 23a' including the first main surface 21a and the second cross-sectional region 23b, 23b' including the second main surface 21b opposite the first main surface 21a, is set to 70% or more in both cross-sectional regions, thereby suppressing temperature rise during repeated energization over a long period of time. As a result, stress relaxation of the terminal due to temperature rise can be reduced, and contact resistance with the connecting member can be maintained low.

[0016] Here, a connecting member (not shown) such as a terminal block is connected adjacent to the first main surface 21a or the second main surface 21b of the plate-like portion 20 of the terminal 1, and a fastening member (not shown) is provided so as to sandwich the plate-like portion 20 and the connecting member. For example, the connecting member can be placed adjacent to the plate-like portion 20 of the terminal 1, and a fastening member such as a bolt can be inserted through the through hole 22 to fasten the terminal 1 and the connecting member with the fastening member so as to sandwich them, thereby connecting them.

[0017] When connecting the terminal 1 and the connecting member, it is preferable to ensure a sufficient contact area at the portion of the plate-shaped portion 20 that comes into contact with the connecting member, thereby reducing contact resistance. In particular, when considering a configuration in which a fastening member such as a bolt is inserted through the through hole 22 to fasten the terminal 1 and the connecting member with a specified torque, it is preferable to ensure a low contact resistance at the periphery of the through hole 22, for example, at the portion where a washer contacts. In either configuration, the contact state between the terminal 1 and the connecting member immediately after fastening the terminal 1 and the connecting member is achieved by connecting the terminal 1 and the connecting member with high contact pressure at least at the portion of the plate-shaped portion 20 where the washer contacts around the through hole 22, thereby ensuring a sufficient contact area and reducing contact resistance. However, when the temperature of the terminal repeatedly changes due to repeated energization, the contact pressure between the terminal 1 and the connecting member decreases due to stress relaxation in the terminal 1, reducing the contact area. Furthermore, the contact resistance increases due to the formation of an oxide film, making the fastening portion between the terminal 1 and the connecting member more susceptible to heat generation.

[0018] The plate-shaped portion 20 of the terminal 1 is generally formed by forging or the like, and such plate-shaped portion 20 often has significant surface distortion and is hard, making it susceptible to stress relaxation due to temperature rise during repeated energization. In this regard, in the present invention, by optimizing the manufacturing conditions of the plate-shaped portion 20 of the terminal 1, the proportion of measurement points in the first cross-sectional regions 23a, 23a' and the second cross-sectional regions 23b, 23b', which are regions near the surface (first main surface 21a and second main surface 21), where the KAM value is in the range of 1° to 4° is adjusted to 70% or more of all measurement points. This reduces the surface distortion of the terminal 1, thereby suppressing temperature rise during repeated energization over a long period of time and also suppressing the accompanying stress relaxation.

[0019] As shown in FIG. 1, the terminal 1 includes a conductor connection portion 10 and a plate-shaped portion 20. The terminal 1 is formed from an aluminum-based material including aluminum (pure aluminum) and aluminum alloys. The aluminum alloy may contain, in addition to aluminum, one or more elements selected from the group consisting of Ti, B, V, Fe, Si, Cu, Mn, Mg, and Zn. Examples of such aluminum-based materials include pure aluminum A1050 and A1070, and aluminum alloy A5052.

[0020] The conductor connection portion 10 of the terminal 1 is configured to connect to a conductor 51, for example, as shown in Fig. 3. Here, 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.

[0021] An insulating coating 52 may be provided on the outer periphery of the portion of the conductor 51 that is not connected to the terminal 1. Furthermore, a sheath 53 may be provided on the outer periphery of the insulating coating 52.

[0022] 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.

[0023] As shown in Fig. 3, one end of the 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 terminal 1 is crimped with the conductor 51 inserted into it, a crimped portion 11 is formed, and an electric wire with a 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 terminal 1.

[0024] 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.

[0025] On the other hand, as shown in FIGS. 1 and 3 , a plate-shaped portion 20 is provided on the other end side of the terminal 1. The plate-shaped portion 20 is formed integrally with the conductor connection portion 10 and has a first main surface 21a and a second main surface 21b opposite the first main surface 21a. A through-hole 22 is formed through the first main surface 21a and the second main surface 21b. This allows a fastening member such as a bolt (not shown) to be inserted through the through-hole 22, making it easier to mechanically and electrically connect the plate-shaped portion 20 of the terminal 1 to a connecting member. Here, from the viewpoint of facilitating insertion of a cylindrical fastening member through the through-hole 22, it is preferable that the through-hole 22 be circular. Note that the connecting member to which the terminal 1 is connected may include a terminal block or the like as well as the plate-shaped portion of another terminal (not shown).

[0026] When the terminal 1 of this embodiment shown in Figure 1 is viewed in cross section when cut by an imaginary plane P including the central axis C of the through hole 22, as shown in Figure 2, the annular portion 20a of the plate-like portion 20, which is defined by the through hole 22 and an imaginary concentric circle R having a diameter 1.5 times the diameter of the through hole 22, is of four cross-sectional regions obtained by dividing the plate-like portion 20 into four equal sections. In a crystal orientation analysis by electron backscatter diffraction (EBSD) performed on a first cross-sectional region 23a, 23a' including the first main surface 21a and a second cross-sectional region 23b, 23b' including the second main surface 21b, the proportion of measurement points in the first cross-sectional region 23a, 23a' and the second cross-sectional region 23b, 23b' where the KAM value is in the range of 1° or more and less than 4° is 70% or more of all measurement points. 2, the four cross-sectional regions obtained from the annular portion 20a of the plate-shaped portion 20 are regions vertically defined by lines R1 and R2 perpendicular to the first and second main surfaces 21a and 21b, including an imaginary concentric circle R having a diameter 1.5 times the diameter of the through-hole 22, and horizontally defined by lines S1-S3 parallel to the first and second main surfaces 21a and 21b, which divide the thickness of the plate-shaped portion into four equal parts. Of the four cross-sectional regions horizontally defined by lines S1-S3 dividing the thickness into four equal parts, the first cross-sectional regions 23a and 23a' including the first main surface 21a and the second cross-sectional regions 23b and 23b' including the second main surface 21b are regions where internal stress occurs due to processes such as forging and polishing performed to form the plate-shaped portion 20. Therefore, it is desirable to remove this internal stress to reduce distortion.

[0027] There are various contact states when fastening the terminal 1 to a connecting member such as a terminal block, but an example of a state with a small contact area is one in which a fastening member such as a bolt is inserted into the through hole 22 and the terminal 1 and the connecting member are fastened with a specified torque. In this state, the terminal 1 and the connecting member are connected with high contact pressure at least in the region of the plate-like portion 20 where the washer around the through hole 22 comes into contact. Therefore, the contact state between the terminal 1 and the connecting member in the annular portion 20a of the plate-like portion 20 defined by the through hole 22 and an imaginary concentric circle R having a diameter 1.5 times the diameter of the through hole 22 is important in determining the contact state at the region where the washer comes into contact. Therefore, by increasing the proportion of measurement points with small KAM values, which are the average orientation differences between adjacent measurement points, in the first cross-sectional regions 23a, 23a' and the second cross-sectional regions 23b, 23b' of the annular portion 20a of the plate-shaped portion 20, particularly in the regions near the surface including the first main surface 21a and the second main surface 21b, distortion in these regions, where connecting members and washers often come into contact, is reduced, thereby suppressing temperature rise when electricity is repeatedly passed through for a long period of time and also suppressing the accompanying stress relaxation.

[0028] In particular, from the viewpoint of further suppressing temperature rise when current is repeatedly applied over a long period of time, in the crystal orientation analysis using the above-mentioned electron backscatter diffraction (EBSD) method, it is preferable that the proportion of measurement points in the first cross-sectional regions 23a, 23a' and the second cross-sectional regions 23b, 23b' where the KAM value is in the range of 1° or more and less than 2° is 70% or more of all measurement points in each region.

[0029] The "KAM value" in this specification can be obtained from crystal orientation analysis data obtained by continuously measuring crystal orientation data using an EBSD detector (OIM5.0 HIKARI, manufactured by TSL) attached to a high-resolution scanning analytical electron microscope (JSM-7001FA, manufactured by JEOL Ltd.), and then calculating (processing) the measured crystal orientation data using analysis software (OIM Analysis, manufactured by TSL Solutions). "EBSD" stands for Electron Backscatter Diffraction, and is a crystal orientation analysis technique that utilizes backscattered electron Kikuchi diffraction that occurs when a copper-based wire, which is a measurement sample, is irradiated with an electron beam inside a scanning electron microscope (SEM). The measurement target is a surface of the terminal 1 in which the plate-shaped portion 20 is embedded in resin and the cross section perpendicular to the extension direction of the plate-shaped portion 20 is mirror-finished by electrolytic polishing. The measurement target includes at least one of the first cross-sectional regions 23a, 23a' and one of the second cross-sectional regions 23b, 23b'. The measurement area can be, for example, 800 μm long and 800 μm wide. Measurements can be performed with a step size of, for example, 0.1 μm. That is, measurement points in the measurement area are set every 0.1 μm. From these measurement points, measurement points with a reliability index (CI) of 0.1 or higher are selected as measurement points, and the KAM value at each measurement point can be calculated using the Map-Kernel Average Misorientation analysis software.

[0030] Here, the CI value is a value used as an index for indexing the crystal orientation analysis pattern obtained by the EBSD method and for evaluating whether the calculated crystal orientation is correct. In other words, the CI value is a value that reflects the reliability of the crystal orientation measured by the EBSD method in a cross section perpendicular to the drawing direction of the above-mentioned copper-based wire rod. This CI value can be calculated from the Map-Confidence Index of the analysis software (OIM Analysis, manufactured by TSL) by analyzing the crystal orientation data obtained in the cross section by the EBSD detector as described above.

[0031] When the terminal 1 is made of pure aluminum A1050 or A1070, it is preferable that the Vickers hardness of each of the first cross-sectional regions 23a, 23a' and the second cross-sectional regions 23b, 23b' is in the range of 30 Hv to 50 Hv. If the Vickers hardness of at least one of the first cross-sectional regions 23a, 23a' and the second cross-sectional regions 23b, 23b' is less than 30 Hv, the strength of the terminal 1 decreases and the terminal 1 becomes too soft. This may cause plastic deformation or fracture of the terminal 1 near the through hole 22 where the fastening load is concentrated during or after fastening an electric wire to the terminal 1. As a result, installation using the terminal 1 may become difficult, and the increased thermal resistance due to the reduced cross-sectional area of ​​the plastically deformed portion may make it difficult to dissipate heat from the terminal 1, which may result in a larger temperature rise during repeated current application than when the Vickers hardnesses of the first cross-sectional regions 23a, 23a' and the second cross-sectional regions 23b, 23b' are all in the range of 30 Hv or more and 50 Hv or less. On the other hand, if the Vickers hardness of at least one of the first cross-sectional regions 23a, 23a' and the second cross-sectional regions 23b, 23b' is greater than 50 Hv, stress relaxation of the plate-shaped portion 20 of the terminal 1 due to temperature rise increases, which may result in a larger temperature rise during repeated current application than when the Vickers hardnesses of the first cross-sectional regions 23a, 23a' and the second cross-sectional regions 23b, 23b' are all in the range of 30 Hv or more and 50 Hv or less.

[0032] Furthermore, when the terminal 1 is made of the aluminum alloy A5052, it is preferable that the Vickers hardness of each of the first cross-sectional regions 23a, 23a' and the second cross-sectional regions 23b, 23b' is in the range of 80 Hv to 150 Hv. If the Vickers hardness of at least one of the first cross-sectional regions 23a, 23a' and the second cross-sectional regions 23b, 23b' is less than 80 Hv, the strength of the terminal 1 will be reduced and the terminal 1 will be too soft. This may cause plastic deformation or breakage of the terminal 1 near the through hole 22 where the fastening load is concentrated during or after fastening an electric wire to the terminal 1. As a result, installation using the terminal 1 may become difficult, and the increased thermal resistance due to the reduced cross-sectional area of ​​the plastically deformed portion may make it difficult to dissipate heat from the terminal 1, which may result in a larger temperature rise during repeated energization than when the Vickers hardnesses of the first cross-sectional regions 23a, 23a' and the second cross-sectional regions 23b, 23b' are all in the range of 80 Hv to 150 Hv. On the other hand, if the Vickers hardness of at least one of the first cross-sectional regions 23a, 23a' and the second cross-sectional regions 23b, 23b' is greater than 150 Hv, stress relaxation of the plate-shaped portion 20 of the terminal 1 due to temperature rise increases, which may result in a larger temperature rise during repeated energization than when the Vickers hardnesses of the first cross-sectional regions 23a, 23a' and the second cross-sectional regions 23b, 23b' are all in the range of 80 Hv to 150 Hv.

[0033] Here, the Vickers hardness (HV) of the first cross-sectional regions 23a, 23a' and the second cross-sectional regions 23b, 23b' can be measured in accordance with the Vickers hardness testing method described in, for example, JIS Z2244 (2009). At this time, a diamond indenter is pressed into the first cross-sectional regions 23a, 23a' and the second cross-sectional regions 23b, 23b' as test pieces with a load (test force) of 0.029 N and a pressing time of 10 seconds. The measurement is performed five times at different measurement locations within the first cross-sectional regions 23a, 23a' or the second cross-sectional regions 23b, 23b', and the average of the measured values ​​can be used as the Vickers hardness measurement result.

[0034] The terminal 1 preferably has one or more surface treatment layers 24 selected from the group consisting of Zn, Sn, Ni, Ni-P, and Cu on at least a portion of one or both of the first and second main surfaces 21a and 21b of the plate-shaped portion 20. Examples of the surface treatment layer 24 include, but are not limited to, a plating layer. In particular, a surface treatment layer 24 made of Sn is commonly used for electrical contacts. Because of its softness, it can easily destroy oxide films, thereby reducing contact resistance. Furthermore, a surface treatment layer 24 made of Ni or Ni-P is a hard material, thereby improving durability. Furthermore, a surface treatment layer 24 made of Cu exhibits intermediate properties between a Sn plating layer and a Ni plating layer, providing a good balance between electrical resistivity and durability. Thus, the constituent elements of the surface treatment layer 24 can be appropriately selected depending on the application of the terminal 1.

[0035] The terminal 1 of this embodiment can be suitably used as an electric wire connecting member used when connecting electric wires to each other or as a terminal connecting member used when connecting an electric wire to an external electronic device. That is, the plate-shaped portion 20 of the terminal 1 may be electrically connected to another electric wire with a terminal or to a connection terminal provided on a connected portion of the external electronic device.

[0036] Next, a method for manufacturing the terminal 1 will be described.

[0037] First, in the forging process, when the terminal 1 is manufactured using a round bar made of an aluminum-based material, the center of the round bar is compressed by forging to form the wire connection portion 10, and then the end opposite the wire connection portion 10 is placed in a mold and compressed by forging to form the plate-like portion 20. On the other hand, when the terminal 1 is manufactured using a tubular material made of an aluminum-based material, the center of the tubular material is compressed by forging to form the wire connection portion 10 and also form the plate-like portion 20.

[0038] After the forging step, a first heat treatment step is preferably performed. The first heat treatment step is performed for the purpose of adjusting the hardness of the region near the surface including the first main surface 21a and the second main surface 21b of the plate-shaped portion 20 (the region including the first cross-sectional regions 23a, 23a' and the second cross-sectional regions 23b, 23b'). The first heat treatment step can be performed at a temperature ranging from 200°C to 250°C for a time ranging from 1 hour to 3 hours. Here, by performing the first heat treatment step, the Vickers hardness of both the first cross-sectional regions 23a, 23a' and the second cross-sectional regions 23b, 23b' can be adjusted to a preferred range.

[0039] After the first heat treatment step, a polishing step is performed in which the first main surface 21a and the second main surface 21b of the plate-shaped portion 20 are polished by sandblasting. This makes the first main surface 21a and the second main surface 21b of the terminal 1 flatter, thereby increasing the contact area with the connecting member connected to the terminal 1 and reducing the contact resistance with the connecting member.

[0040] In the punching step performed after the polishing step, through-holes 22 are formed in the plate-like portion 20 by punching.

[0041] After the punching process, it is preferable to perform a deburring process in which the portions of the through hole 22 that open to the first main surface 21a and the second main surface 21b are chamfered by lathe processing in order to remove burrs around the through hole 22 that were generated in the punching process.

[0042] The subsequent second heat treatment step is performed to remove internal stresses generated during the forging and polishing steps performed on the plate-shaped portion 20. From the viewpoint of removing internal stresses, the second heat treatment step is preferably performed at a temperature of 250°C or less for a long period of time, and more preferably at a temperature ranging from 100°C to 250°C for a period of from 6 hours to 24 hours. By performing the second heat treatment step for 6 hours or more, internal stresses generated during the forging and polishing steps can be removed, reducing distortion in the plate-shaped portion 20 and suppressing temperature rise during repeated energization over a long period of time. In particular, from the viewpoint of further increasing the proportion of measurement points in the first and second cross-sectional regions where the KAM values ​​are in the range of 1° to 2°, thereby further suppressing temperature rise during repeated energization over a long period of time, it is even more preferable to perform the second heat treatment step at a temperature of 180°C or higher.

[0043] When the plate-shaped portion 20 has a surface treatment layer 24, a plating step is performed after the second heat treatment step. As an example, a Ni-P plating layer may be formed by double zincate treatment, and a Sn, Ni, or Cu plating layer may be further formed on the outer side thereof. Furthermore, to improve adhesion with the connecting member, a thin Cu plating layer may be formed on the outer side adjacent to the Ni-P plating layer.

[0044] In this manner, the terminal 1 of this embodiment can be obtained.

[0045] Next, a method for manufacturing the terminal-fitted electric wire 100 in which the terminal 1 and the electric wire 50 are crimped will be described.

[0046] 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 terminal-attached wire 100, destroying the oxide coatings on the conductor connection portion 10 and the conductor 51, and waterproofing the crimped portion 11.

[0047] 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, the electric wire with terminal 100 is obtained.

[0048] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, but includes all aspects encompassed by the concept of the present invention and the scope of the claims, and can be modified in various ways within the scope of the present invention. [Example]

[0049] Next, in order to further clarify the effects of the present invention, examples of the present invention and comparative examples will be described, but the present invention is not limited to these examples of the present invention.

[0050] (Invention Examples 1 to 38, Comparative Examples 1 to 8) The aluminum-based materials used were the types of materials listed in Tables 1 and 2. Of these, in Inventive Examples 1 to 38 and Comparative Examples 1 to 6, a round bar with a diameter of 17 mm was used as the aluminum-based material, and the center of this round bar was compressed by forging to form the conductor connection portion.

[0051] Next, in Inventive Examples 8 to 19, 27 to 38 and Comparative Examples 1, 2, 4, and 5, a first heat treatment step was performed in an atmospheric heating furnace at the temperature and for the time shown in Tables 1 and 2. On the other hand, Inventive Examples 1 to 7, 20 to 26 and Comparative Examples 3 and 6 did not perform the first heat treatment step.

[0052] Thereafter, a polishing process was carried out in which both main surfaces (first main surface and second main surface) of the plate-like portion were polished by sandblasting using an alumina-silicon carbide abrasive (manufactured by Fuji Manufacturing Co., Ltd., model number: Fuji Random A-30) as abrasive particles. Thereafter, a punching process was carried out in which through-holes 22 with a hole diameter of 11 mm were formed in the plate-like portion by punching using a die having an upper die and a lower die, and then chamfering was carried out by lathe processing.

[0053] Subsequently, in Inventive Examples 1 to 38, a second heat treatment step was performed in an atmospheric heating furnace at the temperature and for the time shown in Tables 1 and 2. On the other hand, in Comparative Examples 1 to 6, the second heat treatment step was not performed.

[0054] Thereafter, in Inventive Examples 1, 2, 4 to 21, 23 to 38 and Comparative Examples 1 to 6, a Zn layer, a Ni layer, a Cu layer, and a Sn layer were formed in this order over the entire first and second main surfaces of the plate-shaped portion, forming a plating layer with a total thickness of 16 μm as a surface treatment layer on the plate-shaped portion.On the other hand, in Inventive Examples 3 and 22, no surface treatment layer was formed.

[0055] In this manner, terminals of the present invention and comparative examples were obtained.

[0056] [Various measurement and evaluation methods] The terminals according to the present invention and the comparative example were used to evaluate the following characteristics. The evaluation conditions for each characteristic are as follows, and the results are shown in Tables 1 and 2.

[0057] [1] Measurement of the KAM value at the measurement points included in the first cross-sectional area and the second cross-sectional area The KAM values ​​for the measurement points within the first and second cross-sectional regions were obtained by continuously measuring crystal orientation data using an EBSD detector (TSL, OIM5.0 HIKARI) attached to a high-resolution scanning analytical electron microscope (JEOL, JSM-7001FA). The measured crystal orientation data was then calculated (processed) using analysis software (TSL Solutions, OIM Analysis). The measurement targets were three locations within the first and second cross-sectional regions of the cross-sections containing the central axis of the through-holes, which were obtained by embedding the plate-shaped portions of the terminals obtained in the present invention and comparative examples in resin and then electropolishing a mirror-finished cross section perpendicular to the extension direction of the plate-shaped portions. The measurement regions were 800 μm long x 800 μm wide. Measurements were performed with a step size of 0.1 μm. Among the measurement points in the measurement area, those with a reliability index (CI) of 0.1 or higher were extracted as measurement points, and the analysis software Map-Kernel Average Misorientation was selected to calculate the KAM value at each measurement point.

[0058] Here, the reliability index (CI) was calculated from the Map-Confidence Index of the analysis software (OIM Analysis, manufactured by TSL) by analyzing the crystal orientation data obtained in the cross section by the EBSD detector.

[0059] From the KAM value data obtained in each measurement region, the ratio of the number of measurement points with KAM values ​​in the range of 1° or more and less than 4° to the total number of all measurement points in the first cross-sectional region, and the ratio of the number of measurement points with KAM values ​​in the range of 1° or more and less than 4° to the total number of all measurement points in the second cross-sectional region were calculated, and the ratio of the number of measurement points with KAM values ​​in the range of 1° or more and less than 4° for the first cross-sectional region and the second cross-sectional region with the smaller ratio is listed in Tables 1 and 2. In addition, the ratio of the number of measurement points with KAM values ​​in the range of 1° or more and less than 2° to the total number of all measurement points in the first cross-sectional area, and the ratio of the number of measurement points with KAM values ​​in the range of 1° or more and less than 2° to the total number of all measurement points in the second cross-sectional area were calculated, and the values ​​of the ratio of the number of measurement points with KAM values ​​in the range of 1° or more and less than 2° for the first cross-sectional area and the second cross-sectional area with the smaller ratio are listed in Tables 1 and 2.

[0060] [2] Vickers hardness of the first cross-sectional area and the second cross-sectional area The Vickers hardness (HV) was measured in the first cross-sectional regions 23a, 23a' and the second cross-sectional regions 23b, 23b' using a microhardness tester DUH-211 manufactured by Shimadzu Corporation in accordance with the Vickers hardness testing method described in JIS Z2244 (2009). At this time, the cross sections of the terminals obtained in the examples of the present invention and the comparative examples were each mirror-finished by electrolytic polishing, and for each test piece showing a cross section including the central axis of the through hole, measurements were carried out in the areas corresponding to the first cross-sectional area 23a, 23a' and the second cross-sectional area 23b, 23b', with a load (test force) of 0.029 N when pressing the diamond indenter and a pressing time of 10 seconds, in an environment at room temperature of 25°C, and the average of the measured values ​​obtained when changing the measurement location in the first cross-sectional area 23a, 23a' or the second cross-sectional area 23b, 23b' was used as the Vickers hardness measurement result.

[0061] [3] Heat cycle test To evaluate the 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." For each of the present invention and comparative examples, two aluminum-based electric wires with terminals, each 2 m or longer, were prepared, with identical terminals attached to both ends. These two aluminum-based electric wires with terminals were connected in series via a terminal block, with their second principal surfaces facing each other. The temperature of the aluminum-based electric wire was measured by making a slit in the insulating coating at the center of the aluminum-based electric wire and inserting a thermocouple so that it contacted the conductor of the aluminum-based electric wire. A thermocouple was also soldered to the plate-shaped portion of the terminal where the two aluminum-based electric wires with terminals were connected, and the temperature of the terminal was measured. One cycle consisted of passing a current for one hour at a value set so that the temperature of the aluminum-based electric wire reached 105°C, followed by stopping the current for one hour. The temperature of the terminals one hour after the 25th cycle of current passing was compared with the temperature of the terminals one hour after the 500th cycle of current passing, and the amount of temperature rise Δθ (°C) of the terminals one hour after the 500th cycle of current passing was measured. The smaller the temperature rise, the better, as it allows for suppression of heat generation in the aluminum-based electric wire with terminal.

[0062] The measured terminal temperature rise Δθ was evaluated as "A" when it was 2°C or less. Furthermore, a temperature rise Δθ between more than 2°C and less than 4°C was evaluated as "B." A temperature rise Δθ between more than 4°C and less than 6°C was evaluated as "C." A temperature rise Δθ between more than 6°C and less than 8°C was evaluated as "D." On the other hand, a temperature rise Δθ greater than 8°C was evaluated as "E." In the present invention and comparative examples, the results were evaluated in descending order of "A," "B," "C," "D," and "E," with "A," "B," "C," and "D" being considered pass levels.

[0063] [Table 1]

[0064] [Table 2]

[0065] As shown in Tables 1 and 2, in Examples 1 to 38 of the present invention, when the proportion of measurement points in the first cross-sectional region and the second cross-sectional region where the KAM value was in the range of 1° or more and less than 4° was 70% or more of all measurement points, the temperature rise after the heat cycle test was 8°C or less, whereas in Comparative Examples 1 to 6, the proportion of measurement points in the first cross-sectional region and the second cross-sectional region where the KAM value was in the range of 1° or more and less than 4° was outside the above range, and the temperature rise after the heat cycle test exceeded 8°C.

[0066] From these results, it was confirmed that the terminals of the present invention example have a small temperature rise after the heat cycle test when the proportion of measurement points in the first cross-sectional area and the second cross-sectional area where the KAM value is in the range of 1° or more and less than 4° is within the appropriate range of the present invention. [Explanation of symbols]

[0067] 1 terminal 10 Conductor connection 20 Plate-shaped part 20a Annular portion of plate-shaped part 21a 1st main surface 21b 2nd principal surface 22 Through hole 23a, 23a' 1st cross-sectional area 24 Surface treatment layer 50 Electric wire 51 Conductor 51a Bare wire 52 Insulation coating 53 Sheath 100 Wires with terminals C Center axis of through hole P is an imaginary plane including the central axis of the through hole R is an imaginary concentric circle with a diameter 1.5 times the diameter of the through-hole R1, R2 A line containing imaginary concentric circles with a diameter 1.5 times the diameter of the through-hole Lines dividing the thickness of plate-shaped parts S1 to S3 into four equal parts

Claims

1. Made of aluminum or an aluminum alloy, a conductor connection portion for connecting to the conductor; a plate-like portion integrally formed with the conductor connection portion, having a first main surface and a second main surface opposite to the first main surface, and having a through hole formed therein that penetrates the first main surface and the second main surface; A terminal comprising: A terminal in which, when viewed in a cross section cut along an imaginary plane including the central axis of the through hole, the annular portion of the plate-like portion defined by the through hole and an imaginary concentric circle having a diameter 1.5 times the diameter of the through hole is such that, in a crystal orientation analysis performed by electron backscatter diffraction (EBSD) on a first cross-sectional region including the first main surface and a second cross-sectional region including the second main surface out of four cross-sectional regions obtained by dividing the plate thickness of the plate-like portion into four equal parts, the proportion of measurement points in the first cross-sectional region and the second cross-sectional region where the KAM value is in the range of 1° or more and less than 4° is 70% or more of all measurement points in each of the first cross-sectional region and the second cross-sectional region.

2. 2. The terminal according to claim 1, wherein in the crystal orientation analysis, the proportion of measurement points in the first cross-sectional region and the second cross-sectional region where the KAM value is in the range of 1° or more and less than 2° is 70% or more of all measurement points in each of the first cross-sectional region and the second cross-sectional region.

3. 3. The terminal according to claim 1, wherein at least a portion of one or both of the first main surface and the second main surface has one or more surface treatment layers selected from the group consisting of a Zn layer, a Sn layer, a Ni layer, a Ni—P layer, and a Cu layer.

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