Manufacturing method of electric wire with terminal

Abstract

To provide a manufacturing method of an electric wire with a terminal capable of maintaining low electrical resistance between a conductor and a terminal and ensuring sufficient electrical connection.SOLUTION: A terminal 5 connected to a conductor 3 by compressing a cylindrical portion 6 is provided, the tensile strength of a material used for the conductor 3 is greater than the tensile strength of the material used for the terminal 5, the terminal 5 includes three or more compression portions 10 in the longitudinal direction of the conductor 3, and in a step of forming a third compression portion 103 between a first compression portion 101 and a second compression portion 102, when the cross-sectional area of the conductor 3 is S (mm2), the compression width which is the length along the longitudinal direction of the compression portion 10 is W (mm), and the compression interval which is the length along the longitudinal direction of the non-compression portion 11 is L (mm), the third compression portion 103 is formed such that the value of the compression width W and the value of the compression interval L are expressed by the following formulas (1) and (2), respectively. 0.01×S+2.5≤W≤0.07×S+3.5 (1). -1.0≤L≤0.145×S+3.75 (2).SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for producing an electric wire with a terminal. [Background technology]

[0002] Conventionally, in a terminal-attached electric wire in which a conductor of an electric wire is connected to a terminal, the conductor and terminal have been made of copper or a copper alloy from the viewpoint of electrical conductivity, etc. However, in recent years, from the viewpoint of weight reduction, etc., it has been considered to form the conductor and terminal from an aluminum material (aluminum or an aluminum alloy).

[0003] Prior art document information related to the invention of this application includes Patent Document 1. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] WO 98 / 54790 Summary of the Invention [Problem to be solved by the invention]

[0005] In a terminal-attached electric wire, the stress acting on the connection between the conductor and the terminal decreases over time, which may decrease the contact force between the conductor and the terminal and increase the electrical resistance between them. In particular, aluminum is more susceptible to stress relaxation than copper, and the above-mentioned problems are likely to occur when a terminal made of aluminum material is connected to a conductor made of aluminum material. When the electrical resistance between the conductor and the terminal is high, heat is generated in the terminal-attached electric wire, and this heat can cause the wire to break or cause poor contact.

[0006] Therefore, an object of the present invention is to provide a method for manufacturing an electric wire with a terminal, which can maintain low electrical resistance between the conductor and the terminal and ensure sufficient electrical connection. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems, the present invention provides a method for manufacturing a terminal-attached electric wire comprising: an electric wire including a conductor and an insulating layer covering the conductor; and a terminal having a tubular portion into which the conductor exposed at an end of the electric wire is inserted, the tubular portion being compressed with the conductor inserted into the tubular portion to connect the conductor. The method comprises the steps of: preparing the electric wire and the terminal, the tensile strength of a material used for the conductor being greater than the tensile strength of a material used for the terminal; and connecting the terminal to the conductor by compressing the terminal three or more times with the conductor exposed at the end of the electric wire inserted into the tubular portion to form three or more compressed portions in the terminal. The connecting step includes the steps of forming a third compressed portion between the first and second compressed portions after forming a first compressed portion and a second compressed portion, and in the step, the cross-sectional area of ​​the conductor is reduced to S (mm 2 ), a compression width that is a length of the first to third compressed portions along the longitudinal direction is W (mm), and a compression interval that is a length of a non-compressed portion located between the first to third compressed portions along the longitudinal direction is L (mm), the value of the compression width W and the value of the compression interval L are respectively expressed by the following formulas (1) and (2): 0.01×S+2.5≦W≦0.07×S+3.5 (1) -1.0≦L≦0.145×S+3.75 (2) The third compressed portion is formed so as to satisfy the following relational expression. Effect of the Invention

[0008] According to the present invention, it is possible to provide a method for manufacturing an electric wire with a terminal, which can maintain low electrical resistance between a conductor and a terminal and ensure sufficient electrical connection. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1A is a cross-sectional view of an electric wire with a terminal according to an embodiment of the present invention, and FIG. [Diagram 2]5(a) to 5(c) are diagrams illustrating a method for producing an electric wire with a terminal. [Diagram 3] 13(a) and 13(b) are diagrams illustrating the behavior of a terminal and a conductor when a third compressed portion is formed. [Figure 4] FIG. 1 is an explanatory diagram showing an overview of a high-temperature environment exposure test. [Diagram 5] FIG. 4 is an explanatory diagram showing a method for measuring a resistance ratio. [Figure 6(a)] 13 shows the measurement results of the electrical resistance ratio R2 after a high temperature environmental exposure test when the compression width W was changed. [Figure 6(b)] FIG. 13 is a graph showing the measurement results of the electrical resistance ratio R2 after a high-temperature environment exposure test when the compression interval L is changed. [Figure 6(c)] FIG. 13 is a diagram showing an overlapping state. [Figure 7] FIG. 1A is a graph showing the measurement results of the resistance ratio increase rate after a high-temperature environmental exposure test when the compression width W is changed, and FIG. 1B is a graph showing the measurement results of the resistance ratio increase rate after a high-temperature environmental exposure test when the compression interval L is changed. [Figure 8] 1A is a graph showing the relationship between the conductor cross-sectional area S and the compression width W, which indicate the region where the electrical resistance ratio R2 after a high-temperature environmental exposure test is 100% or less, and FIG. 1B is a graph showing the relationship between the conductor cross-sectional area S and the compression interval L, which indicate the region where the electrical resistance ratio R2 after a high-temperature environmental exposure test is 100% or less. [Figure 9] 1A is a graph showing the relationship between the conductor cross-sectional area S and the compression width W, which shows the region where the electrical resistance ratio R2 after a high-temperature environmental exposure test is 100% or less and the resistance ratio increase rate is 20% or less. FIG. 1B is a graph showing the relationship between the conductor cross-sectional area S and the compression interval L, which shows the region where the electrical resistance ratio R2 after a high-temperature environmental exposure test is 100% or less and the resistance ratio increase rate is 20% or less. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] [Embodiment Mode] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0011] (Outline of terminal-attached electric wire configuration) Fig. 1(a) is a cross-sectional view of an electric wire with a terminal according to the present embodiment, and Fig. 1(b) is an enlarged view of part A. As shown in Figs. 1(a) and 1(b), the electric wire with a terminal 1 includes an electric wire 2 and a terminal 5. The electric wire with terminal 1 can be used as a wiring material for use in buildings, wind power generators, railroad cars, automobiles, etc.

[0012] The electric wire 2 includes a conductor 3 and an insulating layer 4 that covers the conductor 3. The conductor 3 may be a metal wire, a stranded wire formed by stranding a plurality of metal wires, or a composite stranded wire formed by further stranding a plurality of stranded wires. The metal material constituting the conductor 3 may be, for example, pure aluminum or an aluminum alloy (hereinafter, these are referred to as "aluminum material"). Pure aluminum is a material made of Al and unavoidable impurities.

[0013] An example of pure aluminum is electrical pure aluminum (ECAl). An example of aluminum alloy is Al-Zr, Al-Fe-Zr, etc. as follows. Al-Zr is an aluminum alloy having a chemical composition containing 0.03 to 1.5 mass% Zr, 0.1 to 1.0 mass% Fe and Si, and the balance being Al and unavoidable impurities. Also, Al-Fe-Zr is an aluminum alloy containing 0.01 to 0.10 mass% Zr, 0.1 mass% or less Si, 0.2 to 1.0 mass% Fe, 0.01 mass% or less Cu, 0.01 mass% or less Mn, 0.01 mass% or less Mg, 0.01 mass% or less Zn, 0.01 mass% or less Ti, and 0.01 mass% or less V, and the balance being Al and unavoidable impurities. In Al-Zr, "0.1 to 1.0 mass% Fe and Si" has the following meaning. When both Fe and Si are contained, the total concentration of Fe and Si is 0.1 to 1.0 mass%. When Fe is contained but Si is not contained, the Fe concentration is 0.1 to 1.0 mass%. When Si is contained but Fe is not contained, the Si concentration is 0.1 to 1.0 mass%. Here, "not contained" means that it is below the detection limit in, for example, high-frequency inductively coupled plasma atomic emission spectrometry.

[0014] The insulating layer 4 is made of, for example, a fluorine-based resin, an olefin-based resin, a silicone-based resin, etc. The insulating layer 4 is provided over the entire length of the electric wire 2, but in this embodiment, a predetermined length of the insulating layer 4 is removed from the end of the electric wire 2, and a part of the end of the conductor 3 is exposed.

[0015] The terminal 5 includes a cylindrical portion 6 having a hollow portion 7 and an extension portion 8, which are integrally formed. The terminal 5 is, for example, formed by pressing one end of a pipe to form the plate-like extension portion 8. Alternatively, the terminal 5 is, for example, formed by drilling one end of a cylindrical base material to form the cylindrical portion 6, and pressing the other end to form the extension portion 8. The hollow portion 7 has a cylindrical shape that is open on one side.

[0016] The terminal 5 is made of, for example, an aluminum material. More specifically, pure aluminum or an aluminum alloy is preferable. Pure aluminum is a material made of Al and unavoidable impurities. For example, electrically pure aluminum (ECAl) can be mentioned. An example of an aluminum alloy is Al-Fe-Zr as follows. Al-Fe-Zr is an aluminum alloy containing 0.01 to 0.10 mass% Zr, 0.1 mass% or less Si, 0.2 to 1.0 mass% Fe, 0.01 mass% or less Cu, 0.01 mass% or less Mn, 0.01 mass% or less Mg, 0.01 mass% or less Zn, 0.01 mass% or less Ti, and 0.01 mass% or less V, with the balance being Al and unavoidable impurities. It is an alloy.

[0017] The cylindrical portion 6 is formed in a cylindrical shape with a circular cross section, and a hollow portion 7 is formed inside the cylindrical portion 6 into which the conductor 3 exposed at the end of the electric wire 2 can be inserted. The inner diameter N (mm) of the cylindrical portion 6 is opened to a size equal to the outer diameter of the conductor 3 to about 90% to 95% of the outer diameter of the conductor 3, and the conductor 3 exposed at the end of the electric wire 2 is inserted from the opening of the hollow portion 7. When the conductor 3 is inserted from the opening of the hollow portion 7, if the outer diameter of the conductor 3 is compressed with a cable tie or the like until the inner diameter of the conductor 3 becomes approximately equal to that of the cylindrical portion 6, damage to the conductor 3 is reduced and the conductor 3 can be smoothly inserted into the hollow portion 7. The thickness A (mm) of the cylindrical portion 6 is determined from the ratio of the cross-sectional area of ​​the cylindrical portion 6 corresponding to the non-compressed portion 11 of the terminal 5 to the cross-sectional area of ​​the conductor 3 corresponding to the non-compressed portion 11 of the terminal 5 in a cross section perpendicular to the longitudinal direction of the conductor 3 when the terminal 5 with the conductor 3 inserted in the hollow portion 7 is compressed. That is, the cross-sectional area of ​​the cylindrical portion 6 of the non-compressed portion 11 of the terminal 5 is T (mm 2 ) and the cross-sectional area of ​​the conductor 3 of the non-compressed portion 11 of the terminal 5 is S (mm 2 ), it is determined by the formula (T / S). The range of this ratio is preferably 1.0 to 3.0. If it is less than 1.0, the thickness A of the cylindrical portion 6 is small, and there is a risk that the cylindrical portion 6 will stretch due to compression and break. If it is more than 3.0, there is a risk that the cylindrical portion 6 will be mainly compressed and the conductor 5 will not be sufficiently compressed, resulting in an insufficient mechanical joint being obtained. The cross-sectional area T (mm 2 ) is calculated as T = (((2A + N) / 2)² - (N / 2)²) × π. Once the cross-sectional area T of the tubular portion 6 and the inner diameter N of the tubular portion 6, which are calculated from the ratio of the cross-sectional area T of the tubular portion 6 of the non-compressed portion 11 of the terminal 5 to the cross-sectional area S of the conductor 3 of the non-compressed portion 11 of the terminal 5, are determined, the thickness A of the tubular portion 6 can be derived.

[0018] The surface of the terminal 5 and the inner surface of the cylindrical portion 6 may be plated with Sn or Ag. A compound containing conductive particles may be applied to the exposed conductor 3 before it is inserted into the hollow portion 7. A compound may be applied to or filled in the hollow portion 7 of the cylindrical portion 6 before the exposed conductor 3 is inserted. As the compound containing conductive particles, for example, a fluorine-based oil or a silicone-based oil containing conductive particles made of Ni-P, Ni-B, Ni, or Zn, or a mixture of these, may be used. The terminal 5 is connected to the conductor 3 by compressing the hollow portion 7 (cylindrical portion 6) with the conductor 3 inserted in the hollow portion 7.

[0019] The extension 8 is configured as a portion to be connected to an external connection counterpart terminal, a bolt, etc. In the present embodiment, the extension 8 is formed in a plate shape and is provided with a bolt hole 9 into which a bolt, etc. used for connection to an external terminal is inserted.

[0020] In the terminal-attached electric wire 1 according to the present embodiment, three or more compressed portions 10 are formed in the tubular portion 6 of the terminal 5 in the longitudinal direction of the conductor 3. Here, a case where three compressed portions 10 are formed will be described, but the number of compressed portions 10 may be four or more. The tubular portion 6 located between adjacent compressed portions 10 is called a non-compressed portion 11. The compressed portion 10 is a portion compressed by a compression die 20 described later, and has a substantially flat surface in the longitudinal direction. The non-compressed portion 11 is a portion not pressed by the compression die 20, and has a larger outer diameter than the compressed portion 10. A tapered portion is formed between the compressed portion 10 and the non-compressed portion 11 by deformation caused by pressing by the compression die 20, and this tapered portion is included in the non-compressed portion 11. Details of the compressed portion 10 and the non-compressed portion 11 will be described later.

[0021] In the compression step, a pair of compression dies 20 having a split structure are used. The pair of compression dies 20 apply a predetermined pressure to the cylindrical portion 6 of the terminal 5 to compressively deform (plastically deform) the pressurized portion of the cylindrical portion 6. The shape of each compression die 20 may be, for example, a semicircular shape, a convex shape, or a hexagonal shape in cross section. Although not particularly limited in this embodiment, the compression ratio of the conductor 3 is preferably 50% or more and 95% or less. Here, the compression ratio is the ratio of the cross-sectional area of ​​the conductor 3 corresponding to the non-compressed portion 11 of the terminal 5 to the cross-sectional area of ​​the conductor 3 corresponding to the compressed portion 10 in a cross section perpendicular to the longitudinal direction of the conductor 3 when the terminal 5 with the conductor 3 inserted in the hollow portion 7 is compressed. In other words, the cross-sectional area of ​​the conductor 3 corresponding to the non-compressed portion 11 of the terminal 5 is defined as S (mm 2 ) and the cross-sectional area of ​​the conductor 3 corresponding to the compressed portion 10 is D (mm 2 ), it can be calculated using the formula (D / S) × 100. The above compression ratio can suppress the decrease in contact force between the conductor 3 and terminal 5 caused by stress relaxation between the conductor 3 and terminal 5, thereby suppressing an increase in the electrical resistance ratio of the terminal-attached wire 1. When multiple metal wires are used as the conductor 3, the cross-sectional area S of the conductor 3 can be calculated by multiplying the cross-sectional area of ​​a single metal wire by the number of metal wires.

[0022] (Method of manufacturing electric wire with terminal) When manufacturing the electric wire with terminal 1, a preparation step is first performed to prepare the electric wire 2 and the terminal 5. At this time, materials for the conductor 3 and the terminal 5 are selected so that the tensile strength of the material used for the conductor 3 is greater than that of the material used for the terminal 5 (for example, greater by 20 MPa or more). For example, when ECAl is used as the material for the terminal 5, materials having a greater tensile strength than ECAl, such as Al-Fe-Zr (tensile strength difference: about 24 MPa or more) and Al-Zr (tensile strength difference: about 46 MPa or more), can be used as the material for the conductor 3. Even when the same material is used for the conductor 3 and the terminal 5, the tensile strength of the material can be adjusted by the heat treatment conditions and the degree of processing during the manufacturing process.

[0023] In the preparation step, a predetermined length of the insulating layer 4 of the electric wire 2 is removed from an end of the electric wire 2 in the longitudinal direction to expose a part of the conductor 3. Then, the exposed part of the conductor 3 of the electric wire 2 is inserted into the hollow portion 7 formed in the tubular portion 6 of the terminal 5.

[0024] Thereafter, a connection step is performed in which the tubular portion 6 of the terminal 5 is compressed three or more times with the conductor 3 inserted in the hollow portion 7 to form three or more compressed portions 10 in the terminal, thereby connecting the terminal 5 to the conductor 3. Here, a case in which the tubular portion 6 of the terminal 5 is compressed three times to form three compressed portions 10 in the terminal will be described.

[0025] In the connection step, first, as shown in Fig. 2(a), the vicinity of the end portion of the tubular portion 6 on the extension portion 8 side (the vicinity of the end portion of the conductor 3) is pressed by a compression die 20 to compress the tubular portion 6 and form a first compressed portion 101. Thereafter, as shown in Fig. 2(b), the vicinity of the end portion of the tubular portion 6 on the opening side of the hollow portion 7 (the insulating layer 4 side) is pressed by a compression die 20 to compress the tubular portion 6 and form a second compressed portion 102.

[0026] Thereafter, as shown in FIG. 2(c), the intermediate position between the first compressed portion 101 and the second compressed portion 102 is pressed by the compression die 20 to compress the tubular portion 6 to form the third compressed portion 103. In this manner, the connection step includes a step of forming a new third compressed portion 103 between the adjacent first and second compressed portions 101 and 102 that have already been formed. The non-compressed portion 11 is formed between the first compressed portion 101 and the third compressed portion 103, and between the third compressed portion 103 and the second compressed portion 102. Here, the case where the second compressed portion 102 is formed after the first compressed portion 101 has been described, but the first compressed portion 101 may be formed after the second compressed portion 102 has been formed, or the first compressed portion 101 and the second compressed portion 102 may be formed simultaneously.

[0027] The first to third compressed portions 101-103 are formed by applying a predetermined pressure to the entire circumference of the tubular portion 6 using a compression die 20, thereby compressively deforming (plastically deforming) the tubular portion 6. In this embodiment, each of the compressed portions 101-103 has a hexagonal cross-sectional shape perpendicular to the longitudinal direction (axial direction) of the conductor 3. By forming each of the compressed portions 101-103, the terminal 5 can be compressed and connected to the conductor 3 to obtain the terminal-attached electric wire 1.

[0028] (Details of the Compression Unit 10 and the Non-Compression Unit 11) Here, the behavior of the terminal 5 and the conductor 3 when the compressed portion 10 is formed will be considered. As shown in Fig. 3(a), when the terminal 5 and the conductor 3 are compressed by the compression die 20, both the terminal 5 (cylindrical portion 6) and the conductor 3 are stretched in the longitudinal direction due to the influence of the compression. In this embodiment, since the tensile strength of the material used for the terminal 5 is smaller than the tensile strength of the material used for the conductor 3, the terminal 5 is deformed more, and the difference in the amount of stretch between the terminal 5 and the conductor 3 is ΔL.

[0029] 3(b), the state in which the first and second compressed portions 101, 102 are formed is taken as the initial state. In this state, when a compression die 20 is used to press a position intermediate between the first and second compressed portions 101, 102, the terminal 5 tends to stretch longer than the conductor 3 by ΔL due to the influence of the pressing force, and a contact force (axial contact force) between the terminal 5 and the conductor 3 is generated at the first and second compressed portions 101, 102, thereby reducing the contact resistance between them.

[0030] Due to the influence of the difference ΔL in the amount of elongation between the terminal 5 and the conductor 3, the contact force (axial contact force) between the terminal 5 and the conductor 3 can be increased, thereby reducing the contact resistance between them. The contact force between the terminal 5 and the conductor 3 decreases with time, but in this embodiment, a force that causes the terminal 5 and the conductor 3 to pull each other not only in the radial direction but also in the longitudinal direction (axial direction), i.e., an axial contact force, is applied, so that the loosening of the radial contact force is supported by the axial contact force, thereby suppressing the increase in the resistance value between the terminal 5 and the conductor 3 due to time.

[0031] In order to increase the contact force (axial contact force) between the terminal 5 and the conductor 3 and to reduce the contact resistance, the elongation strain should be increased. The elongation strain ε is expressed by the following formula, where ΔL is the elongation due to compression and L is the compression interval (the interval between the compressed parts 10 adjacent in the longitudinal direction in FIG. 3(b), i.e., the length along the longitudinal direction of the non-compressed parts 11). ε = ΔL / L Therefore, by increasing the elongation ΔL due to compression and decreasing the compression interval L, the elongation strain due to compression is increased, and the contact force (axial contact force) between the terminal 5 and the conductor 3 is increased, making it possible to further reduce the contact resistance between them.

[0032] In order to increase the difference ΔL in the amount of elongation between the terminal 5 and the conductor 3 due to compression, the compression width W, which is the length along the longitudinal direction of the compressed portion 10, may be set to an appropriate width according to the cross-sectional area of ​​the conductor. The compression width W can be controlled by adjusting the size of the compression die 20 used, and the compression interval L can be controlled by adjusting the position of each of the compressed portions 101-103 (the position along the longitudinal direction of the conductor 3).

[0033] The inventors conducted an experiment to examine the influence of the compression width W and the compression interval L. First, the compression load by the compression die 20 was fixed at 12 t, the compression interval L (mm) was fixed at 7 mm, and the compression width W (mm) was changed. 2 and 250mm 2 A wire 2 having a conductor 3 with a conductor cross-sectional area of ​​50 mm 2 The compression ratio of the specimens was set to 60% to 95%, and the conductor cross-sectional area was set to 250 mm 2 The compression ratio for the samples was 70% to 95%. 2 When an electric wire 2 having a diameter of about 10 mm is used, the inner diameter N of the cylindrical portion 6 of the terminal 5 is 10.2 mm, the thickness A is 3.0 mm, and the conductor cross-sectional area is 250 mm 2When using an electric wire 2 with a diameter of about 23.6 mm, the inner diameter N of the cylindrical portion 6 of the terminal 5 is 21.8 mm and the thickness A is 5.2 mm (in the following experiments, terminals 5 of the same size are used). As the compressed width W (mm) increases, the compression ratio of the conductor 3 also increases.

[0034] (Measurement of resistance ratio increase rate) Next, assuming that the terminal 5 is compressed and the extension portion 8 of the terminal-attached electric wire 1 connected to the conductor 3 is connected to an external terminal of the connection partner with a bolt or the like, an aluminum plate 13 is fixed to the extension portion 8 with a bolt (not shown) to prepare a high-temperature environment exposure test sample. As shown in FIG. 4, this high-temperature environment exposure test sample was placed in a thermostatic chamber 14 set at 200° C. and held in the atmosphere for 100 hours, and a high-temperature environment exposure test was performed in which the sample was taken out of the thermostatic chamber every 10 hours and the bolt was attached and detached. The high-temperature environment exposure test simulated the current-carrying test environment. Note that, although the case where the aluminum plate is fixed to the lower side of the extension portion 8 is shown, the same results as when the aluminum plate is fixed to the upper side of the extension portion 8 are obtained when the aluminum plate is fixed to the lower side of the extension portion 8.

[0035] The electrical resistance ratio was measured before and after the high-temperature environmental exposure test, and the resistance ratio increase rate was calculated from the electrical resistance ratio before and after the test. The resistance ratio increase rate (%) can be calculated from the formula ((R2-R1) / R1)×100, where R1 and R2 are the electrical resistance ratios between the conductor 3 and the terminal 5 before and after the high-temperature environmental exposure test (after 100 hours), respectively.

[0036] (Measurement of electrical resistance ratio) Here, the electrical resistance ratio (initial resistance ratio) R1 of the terminal-attached electric wire 1 before the high-temperature environment exposure test was measured by the so-called four-terminal method. The four-terminal method will be described with reference to FIG.

[0037] First, a constant current of 1A is supplied to the entire terminal-attached electric wire 1, and the electrical resistance value R0 between points P and Q is measured. Here, point P is one end of the tubular portion 6 of the terminal 5, and is a portion corresponding to the tip of the inserted conductor 3. Point Q is a portion of the conductor 3 that is not in contact with the terminal 5. Point S is the other end of the tubular portion 6 of the terminal 5, and is a portion of the entrance portion into which the conductor 3 is inserted. The initial resistance ratio R1 (%) is calculated by the formula {(R0-L2×α) / (L1×α)}×100, where L1 is the distance between points P and S, L2 is the distance between points Q and S, and α is the electrical resistance value per unit length of the conductor 3. The electrical resistance value per unit length of the conductor 3 may be measured in advance, or the electrical resistance value between L2 may be measured and divided by the length between L2 to be used as the electrical resistance value per unit length.

[0038] The electrical resistance ratio R2 after the high-temperature environmental exposure test was measured by the above-mentioned four-terminal method, which was the same as that used to measure the electrical resistance ratio (initial resistance ratio) before the test, after the terminal-attached electric wire 1 was cooled to room temperature. Specifically, a constant current of 1A was supplied to the entire terminal-attached electric wire 1 after the high-temperature environmental exposure test, and the electrical resistance value R between points P and Q was measured. The electrical resistance value α per unit length of the conductor 3 does not change before and after the high-temperature environmental exposure test, and the same value is used. The electrical resistance ratio R2 (%) is calculated by the formula {(R-L2×α) / (L1×α)}×100. The resistance value was measured using a resistance meter manufactured by Hioki Electric Industry Co., Ltd. The experimental results of the electrical resistance ratio R2 after the high-temperature environmental exposure test (after 100 hours of exposure) are shown in Figure 6(a).

[0039] As shown in FIG. 6(a), the cross-sectional area of ​​the conductor 3 is 50 mm 2 In the specimen, the electrical resistance ratio R2 decreases as the compression width W increases, but if the compression width W is made too large, the electrical resistance ratio R2 starts to increase, and it was found that there exists a compression width W at which the electrical resistance ratio R2 becomes a minimum value. 2 It was found that the electrical resistance ratio R2 of the sample decreased as the compression width W increased.

[0040] Similarly, the cross-sectional area of ​​conductor 3 is 50 mm 2The compression width W is 3 mm, and the cross-sectional area of ​​the conductor 3 is 250 mm 2 The electrical resistance ratio R2 after the high temperature environment exposure test was obtained by changing the compression interval L while keeping the compression width W constant at 7 mm and the compression load by the compression die 20 constant at 12 t. The experimental results are shown in Figure 6(b). 2 In the specimen with the cross-sectional area of ​​the conductor 3, the electrical resistance ratio R2 decreases as the compression interval L increases, but if the compression interval L is made too large, the electrical resistance ratio R2 starts to increase, and it was found that there exists a compression interval L at which the electrical resistance ratio R2 has a minimum value. 2 It was found that the electrical resistance ratio R2 of the sample with the compression interval L increased as the compression interval L increased. In addition, FIG. 6(b) also includes an area where the compression interval L is negative, which indicates a state where the compressed parts 10 overlap. FIG. 6(c) shows the overlapped state. The compression widths W of the first compressed part 101, the second compressed part 102, and the third compressed part 103 pressed by the compression die 20 overlap by the compression interval L. The compression interval L can be calculated as L=(WL-3W) / 2, where WL is the distance from the right end of the first compressed part 101 to the left end of the second compressed part 102. Here, when the compressed parts 10 overlap, the value of the compression interval L is negative.

[0041] 7(a) is a graph showing the compression width W on the horizontal axis and the resistance ratio increase rate on the vertical axis. 2 The specimens were conductors with a cross-sectional area of ​​250 mm 2 For both samples, the compression interval L was kept constant at 7 mm, and the compression width W was changed to obtain the resistance ratio increase rate before and after the high temperature environmental exposure test. As shown in Figure 7(a), for both samples, the resistance ratio increase rate basically decreased as the compression width W increased, but if the compression width W was made too large, the resistance ratio increase rate began to increase, and it was found that there exists a compression width W at which the resistance ratio increase rate becomes a minimum value.

[0042] 7(b) is a graph showing the compression interval L on the horizontal axis and the resistance ratio increase rate on the vertical axis.2 The compression width W is 3 mm, and the cross-sectional area of ​​the conductor 3 is 250 mm 2 The compression width W was kept constant at 7 mm, and the compression interval L was changed to determine the increase in resistance ratio before and after the high temperature environmental exposure test.

[0043] As shown in FIG. 7(b), the cross-sectional area of ​​the conductor 3 is set to 50 mm 2 The cross-sectional area of ​​the conductor 3 is 250 mm 2 In both samples, the resistance ratio increase rate decreases as the compression interval L becomes smaller, but if the compression interval L is made too small, the resistance ratio increase rate turns to increase, and it was found that there is a compression interval L where the resistance ratio increase rate becomes a minimum value. In addition, FIG. 7(b) also includes an area where the compression interval L is negative, which represents a state where the compressed parts 10 overlap. The overlapping state in FIG. 7(b) is also the same as the overlapping state shown in FIG. 6(c). The compression widths W of the first compressed part 101, the second compressed part 102, and the third compressed part 103 pressed by the compression die 20 overlap by the compression interval L.

[0044] In FIG. 8(a), the horizontal axis represents the cross-sectional area S (mm 2 ) and the vertical axis is the compression width W (mm). Also, FIG. 8(b) is a graph in which the horizontal axis is the cross-sectional area S (mm 2 ), and the vertical axis is the compression interval L (mm). 2 More than 500mm 2 Under the following conditions, we found the compression width W (mm) and compression interval L (mm) that ensure the electrical resistance ratio R2 after the high-temperature environmental exposure test is 100% or less. As a result, it was found that the electrical resistance ratio R2 after the high-temperature environmental exposure test is 100% or less when the compression width W (mm) satisfies the following formula (1) and the compression interval L (mm) satisfies the following formula (2). 0.01×S+2.5≦W≦0.07×S+3.5 (1) -1.0≦L≦0.145×S+3.75 (2) The region indicated by formula (1) is the shaded area in Fig. 8(a). Similarly, the region indicated by formula (2) is the shaded area in Fig. 8(b). For example, when the cross-sectional area S of the conductor 3 is 50 mm 2 In this case, the compression width W can be selected to be 3 mm or more and 7 mm or less, and the compression interval L can be selected to be -1 mm or more and 11 mm or less. By using the compression width W and compression interval L within the above range, the electrical resistance ratio R2 after the high-temperature environmental exposure test will be 100% or less.

[0045] An even better compression width W (mm) and compression interval L (mm) were found when both of the following conditions (1) and (2) were satisfied. The range of options is narrower than that of the compression width W and compression interval L that satisfy the target specification of 100% or less electrical resistance ratio R2 after the high-temperature environmental exposure test described above. (1) The electrical resistance ratio R2 after a high-temperature environmental exposure test is 100% or less. (2) The resistance ratio increase rate is 20% or less.

[0046] In FIG. 9(a), the horizontal axis represents the cross-sectional area S (mm 2 9(b) is a graph in which the horizontal axis represents the cross-sectional area S (mm 2 ), and the vertical axis is the compression interval L (mm). 2 More than 500mm 2 Under the following conditions, we found the compression width W (mm) and compression interval L (mm) that satisfy both target specifications: (1) the electrical resistance ratio R2 after the high-temperature environmental exposure test is 100% or less, and (2) the increase in the resistance ratio after the high-temperature environmental exposure test is 20% or less. As a result, we found that when the compression width W (mm) satisfies the formula (3) shown below and the compression interval L (mm) satisfies the formula (4) shown below, both target specifications: (1) the electrical resistance ratio R2 after the high-temperature environmental exposure test is 100% or less, and (2) the increase in the resistance ratio before and after the high-temperature environmental exposure test is 20% or less are satisfied. 0.01×S+2.5≦W≦0.035×S+4.25 (3) -1.0≦L≦0.09×S+4.5 (4) The region indicated by formula (3) is the shaded area in Fig. 9(a). Similarly, the region indicated by formula (4) is the shaded area in Fig. 9(b). For example, when the cross-sectional area S of the conductor 3 is 50 mm 2 In this case, the compression width W can be selected to be 3 mm or more and 6 mm or less, and the compression interval L can be selected to be -1 mm or more and 9 mm or less. By using the compression width W and compression interval L within the above range, the electrical resistance ratio R2 after the high temperature environment exposure test will be 100% or less, and the resistance ratio increase rate will be 20% or less.

[0047] From the above results, by forming the compressed portion 10 by adjusting the compression width W and compression interval L so as to satisfy formulas (1) and (2), an electric wire with terminal 1 having a small electrical resistance ratio R2 after a high-temperature environmental exposure test and satisfying the above-mentioned target specifications can be obtained. More preferably, by forming the compressed portion 10 by adjusting the compression width W and compression interval L so as to satisfy formulas (3) and (4), an electric wire with terminal 1 having a small electrical resistance ratio R2 and resistance ratio increase rate after a high-temperature environmental exposure test and satisfying the above-mentioned target specifications can be obtained.

[0048] That is, in the terminal-attached electric wire 1 according to the present embodiment, the compression width W (mm) and compression interval L (mm) are determined based on the cross-sectional area S (mm 2 ) is expressed by the following equation. 0.01×S+2.5≦W≦0.07×S+3.5 (1) -1.0≦L≦0.145×S+3.75 (2) Even within this range, the resistance ratio increase rate may exceed 20% depending on the compression width W and compression interval L. In order to satisfy both (1) and (2) in the above target specifications, it is more preferable that the compression width W (mm) and compression interval L (mm) are within the conductor cross-sectional area S (mm 2 ) should be the relation: 0.01×S+2.5≦W≦0.035×S+4.25 (3) -1.0≦L≦0.09×S+4.5 (4)

[0049] For example, when the outer diameter of the conductor 3 is small, if the compression width W is too small, the target specifications may not be satisfied. 2 More than 500mm 2 It would be better if it was less than this.

[0050] (Functions and Effects of the Embodiments) As described above, in the terminal-attached electric wire 1 according to the present embodiment, the tensile strength of the material used for the conductor 3 is greater than the tensile strength of the material used for the terminal 5, the terminal 5 has three or more compressed portions 10 in the longitudinal direction of the conductor 3, and the cross-sectional area of ​​the conductor 3 is set to S (mm 2 ), the compressed width, which is the length of the compressed portion 10 along the longitudinal direction, is W (mm), and the compressed interval, which is the length of the non-compressed portion 11 located between adjacent compressed portions 10 along the longitudinal direction, is L (mm). The values ​​of the compressed width W (mm) and the compressed interval L (mm) are respectively expressed by the following formulas (1) and (2): 0.01×S+2.5≦W≦0.07×S+3.5 (1) -1.0≦L≦0.145×S+3.75 (2) More preferably, the value of the compression width W (mm) and the compression interval L (mm) satisfy the following relational expression. The values ​​are expressed by the following formulas (3) and (4), 0.01×S+2.5≦W≦0.035×S+4.25 (3) -1.0≦L≦0.09×S+4.5 (4) The following relation is satisfied.

[0051] By configuring it in this manner, it is possible to increase the contact force (axial contact force) between the conductor 3 and the terminal 5 regardless of the size of the conductor 3 (outer diameter or conductor cross-sectional area), and a terminal-attached electric wire 1 can be realized that maintains low electrical resistance between the conductor 3 and the terminal 5 and ensures sufficient electrical connection.

[0052] (Summary of the embodiment) Next, the technical ideas grasped from the above-described embodiment will be described by using the reference numerals and the like in the embodiment. However, the reference numerals and the like in the following description do not limit the components in the claims to the members and the like specifically shown in the embodiment.

[0053] [1] A terminal-attached electric wire (1) comprising: an electric wire (2) including a conductor (3) and an insulating layer (4) covering the conductor (3); and a terminal (5) having a hollow portion (7) into which the conductor (3) exposed at an end of the electric wire (2) is inserted, the hollow portion (7) being compressed with the conductor (3) inserted into the hollow portion (7) to be connected to the conductor (3), wherein the tensile strength of a material used for the conductor (3) is greater than the tensile strength of a material used for the terminal (5), the terminal (5) has three or more compressed portions (10) in the longitudinal direction of the conductor (3), and the cross-sectional area of ​​the conductor (3) is S (mm 2 ), a compression width, which is the length of the compressed portion (10) along the longitudinal direction, is W (mm), and a compression interval, which is the length of a non-compressed portion (11) located between adjacent compressed portions (10) along the longitudinal direction, is L (mm), the value of the compression width W and the value of the compression interval L are respectively expressed by the following formulas (1) and (2): 0.01×S+2.5≦W≦0.07×S+3.5 (1) -1.0≦L≦0.145×S+3.75 (2) A terminal-attached electric wire (1) that satisfies the following relationship:

[0054] [2] The value of the compression width W and the value of the compression interval L are expressed by the following formulas (3) and (4), respectively. 0.01×S+2.5≦W≦0.035×S+4.25 (3) -1.0≦L≦0.09×S+4.5 (4) The electric wire with terminal (1) according to [1] satisfies the following relational expression.

[0055] [3] The electric wire with terminal (1) according to [1] or [2], wherein the terminal (5) is made of an aluminum material, and the conductor (3) is made of an aluminum material having a tensile strength greater than that of the aluminum material used for the terminal (5).

[0056] [4] A method for manufacturing a terminal-attached electric wire (1) including an electric wire (2) including a conductor (3) and an insulating layer (4) covering the conductor (3), and a terminal (5) having a hollow portion (7) into which the conductor (3) exposed at an end of the electric wire (2) is inserted, the hollow portion (7) being compressed with the conductor (3) inserted into the hollow portion (7), wherein the tensile strength of a material used for the conductor (3) is greater than the tensile strength of a material used for the terminal (5). The method includes a preparation step of preparing the electric wire (2) and the terminal (5), and a connection step of compressing the terminal (5) three or more times in a state where the conductor (3) exposed at the end of the electric wire (2) is inserted into the hollow portion (7) to form three or more compressed portions (10) in the terminal (5), thereby connecting the terminal (5) to the conductor (3). The connection step includes a step of forming a new compressed portion (10) between adjacent compressed portions (10) that have already been formed, and a step of reducing the cross-sectional area of ​​the conductor (3) by S (mm 2 ), a compression width, which is the length of the compressed portion (10) along the longitudinal direction, is W (mm), and a compression interval, which is the length of a non-compressed portion (11) located between adjacent compressed portions (10) along the longitudinal direction, is L (mm), the value of the compression width W and the value of the compression interval L are respectively expressed by the following formulas (1) and (2): 0.01×S+2.5≦W≦0.07×S+3.5 (1) -1.0≦L≦0.145×S+3.75 (2) forming the compressed portion (10) so as to satisfy the following relational expression.

[0057] Although the embodiment of the present invention has been described above, the invention according to the claims is not limited to the embodiment described above. It should be noted that not all of the combinations of features described in the embodiment are essential to the means for solving the problems of the invention. The present invention can be modified appropriately without departing from the spirit of the invention. [Explanation of symbols]

[0058] 1...Terminal attached wire 2...Electric wire 3…Conductor 4…Insulating layer 5…Terminal 6...Cylindrical part 7...Hollow part 8...Extension part 9…Bolt hole 10...Compression section 101...first compression section 102...second compression section 103...Third compression section 11...Non-compressed section

Claims

1. An electric wire including a conductor and an insulating layer covering the conductor; a terminal having a tubular portion into which the conductor exposed at an end of the electric wire is inserted, the tubular portion being compressed with the conductor inserted into the tubular portion to be connected to the conductor; A method for manufacturing an electric wire with a terminal, comprising: a preparation step of preparing the electric wire and the terminal, the tensile strength of a material used for the conductor being greater than the tensile strength of a material used for the terminal; a connecting step of inserting the conductor exposed at the end of the electric wire into the cylindrical portion, compressing the terminal three or more times to form three or more compressed portions in the terminal, thereby connecting the terminal to the conductor, The connecting step includes a step of forming a third compressed portion between the first and second compressed portions after forming a first compressed portion and a second compressed portion, and in this step, the cross-sectional area of ​​the conductor is set to S (mm ２ ), a compressed width that is a length of the first to third compressed portions along the longitudinal direction is W (mm), and a compressed interval that is a length of a non-compressed portion located between the first to third compressed portions along the longitudinal direction is L (mm), the value of the compressed width W and the value of the compressed interval L are respectively expressed by the following formulas (1), (2), (3), and (4). 0.01×S+2.5≦W≦0.07×S+3.5 (1) −1.0≦L≦0.145×S+3.75 ... (2) 0.01×S+2.5≦W≦0.035×S+4.25 (3) −1.0≦L≦0.09×S+4.5 (4) The third compression portion is formed so as to satisfy the relational expression: The third compressed portion is a compressed and deformed portion that is compressed and deformed over the entire circumferential direction of the cylindrical portion. A manufacturing method for electric wire with terminal.

2. the terminal is made of an aluminum material; The conductor is made of an aluminum material having a tensile strength greater than that of an aluminum material used for the terminal. A method for producing the electric wire with terminal according to claim 1.

3. The cross-sectional area of ​​the cylindrical portion of the terminal is T (mm ２ ) In this case, T / S calculated from the cross-sectional area T of the cylindrical portion and the cross-sectional area S of the conductor is 1.0 or more and 3.0 or less. A method for producing an electric wire with a terminal according to claim 1 or 2.

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