Electric wire with terminal, wiring harness, and manufacturing method of electric wire with terminal

Abstract

To provide a terminal-equipped wire or the like capable of achieving both connection strength and connection resistance.SOLUTION: A terminal-equipped wire 10 is configured by electrically connecting a terminal 1 and a coated conductor 11. A conductor crimping portion 7 of the terminal 1 is formed into a substantially tubular shape by rolling the ends of a flat plate-shaped material such that the ends thereof meet and welding at least a part of the butting portion, and a weld bead 23 is formed at the welded butting portion. Here, the weld bead 23 has an uneven shape in the circumferential direction on the inner surface side of the wire crimping portion 7. The uneven shape on the inner surface of the conductor crimping portion 7 increases an area where a conductor 13 and the conductor crimping portion 7 are caught, so that the wire can be prevented from being pulled out, and the effect of destroying an oxide film due to the uneven shape can also be expected.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an electric wire with a terminal for use in, for example, an automobile. [Background technology]

[0002] Typically, automotive wire harnesses are bundled together after crimp terminals are connected to the conductors of coated conductors, and are then wired as signal wires for automobiles, etc. In general, coated conductors and crimp terminals are connected by removing the coating from the tip of the coated conductor, crimping the exposed conductor with the conductor crimping part, and crimping the coating with the coating crimping part. In this process, an oxide film with poor conductivity is formed on the surface of the conductor, but this oxide film can be destroyed by strongly compressing the conductor crimping part when it is crimped. Therefore, the wires that make up the conductor come into contact with the conductor crimping part of the crimping terminal, and electrical conductivity is obtained between the crimping terminal and the conductor crimping part.

[0003] However, particularly in wire harnesses used in automobiles, thinner wires than before are sometimes used to reduce weight, and the wires are as thin as 0.3sq (sq:mm 2 There is a demand for thin electric wires with a diameter of 0.1 mm or less (meaning 0.1 mm or less). In the case of thin electric wires, excessive compression can cause the wires to break or become damaged, resulting in a significant decrease in the tensile strength of the joint. However, if the compression is weakened, as mentioned above, the oxide film is not broken down sufficiently, resulting in an increase in the resistance of the joint.

[0004] That is, strong compression causes damage to the wires and reduces the strength of the crimped portion, while weak compression does not destroy the oxide film sufficiently, increasing the resistance of the crimped portion and causing the crimped portion to be pulled out due to insufficient crimping, making it difficult to ensure the strength of the crimped portion. Thus, it is difficult to control the balance between conductivity and tensile strength by the compression ratio alone, especially for thin-diameter coated electric wires. For this reason, a connector that makes it easy to control the balance between conductivity and tensile strength by the compression ratio with a single crimping is desired.

[0005] In response to this, electric wires containing tension members have been considered. For example, when using an electric wire made of a conductor with a tensile strength of about 30 N, in order to ensure a tensile strength exceeding 80 N required for electric wires for automobiles, an electric wire containing a tension member has been proposed in which a conductor wire is wound in a spiral shape around the outer periphery of a metallic or nonmetallic tension member. For such an electric wire, the conductor is stripped in stages to expose the tension member, which is then inserted into a sleeve, the tension member is crimped with a steel clamp, and the two are integrated with a curable resin such as an adhesive, and the conductor portion is crimped with an aluminum clamp or the like (Patent Document 1).

[0006] In addition, a coated electric wire has been proposed, which includes a conductor portion formed by bundling multiple strands together, and a fibrous tensile member disposed in the valleys between the strands on the outer periphery of the conductor portion and the inner periphery of the coating material (Patent Document 2). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Utility Model Application Publication No. 61-046827 [Patent Document 2] JP 2012-3856 A Summary of the Invention [Problem to be solved by the invention]

[0008] However, in both Patent Document 1 and Patent Document 2, for example, when a thick-diameter covered conductor is used to connect to a crimp terminal, crimping can be performed at the conductor crimping portion with a compression ratio that satisfies both connection strength and connection resistance, but as the diameter of the electric wire becomes smaller, the range of appropriate crimping conditions for both connection strength and electrical resistance becomes narrower. This is because, as mentioned above, if an attempt is made to ensure connection strength, the conductor breaks and the connection resistance increases, and if emphasis is placed on connection resistance, connection strength cannot be obtained, which can cause the electric wire to come loose. Thus, the smaller the diameter of the electric wire, the more difficult it becomes to achieve both connection strength and electrical resistance.

[0009] Also, for example, in Patent Document 1, if the compression rate during crimping is low (i.e., strong compression), the tensile strength is reduced due to damage to the tensile member, and if the compression rate during crimping is high (i.e., low compression), the resistance of the crimped portion increases. Also, when connecting a conventional electric wire with a tensile member, a step stripping operation and separate crimping processes for crimping the tensile member and crimping the conductor are required. This results in a large number of parts, an increase in the number of work steps, and high costs. In particular, when the diameter of the electric wire becomes narrow, the step stripping itself becomes difficult. Thus, Patent Document 1 has a problem in that the manufacturing process becomes complicated, resulting in increased processing costs.

[0010] Also, Patent Document 2 discloses an example in which a fibrous tension member is provided between conductor wires to improve strength without degrading electrical properties. However, like Patent Document 1, Patent Document 2 does not solve the problem that if the compression ratio during crimping is low, the tension member is damaged and the tensile strength is reduced, and if the compression ratio during crimping is high, the resistance of the crimped portion increases.

[0011] The present invention has been made in view of the above problems, and has an object to provide an electric wire with a terminal or the like that is capable of achieving both connection strength and connection resistance. [Means for solving the problem]

[0012] In order to achieve the above-mentioned object, a first aspect of the present invention is an electric wire with terminal in which a covered conductor wire and a terminal are electrically connected, before The covered conductor has a tension member, a conductor, and a coating portion that covers the tension member and the conductor, and the cross-sectional area of ​​the conductor is 0.3 sq. or less. The terminal includes a conductor crimping portion to which the conductor exposed from the coating portion at the tip of the covered conductor is crimped, and a coating crimping portion to which the coating portion of the covered conductor is crimped. The conductor crimping portion is formed by rolling the ends of a flat plate-shaped material so that they butt together, and at least a portion of the butt portion is welded. Weld bead It is formed in a generally tubular shape, A welding mark on an opposing surface is formed on an inner surface of the conductor crimping portion on the opposing surface side of the butt portion in addition to the weld bead, The conductor is an electric wire with a terminal, characterized in that the conductor is crimped from the entire circumferential circumference of the conductor in the conductor crimping portion.

[0013] It is desirable that the inner surface area of ​​the weld bead of the butt portion on the inner surface of the conductor crimping portion is greater than 20% of the total inner surface area of ​​the conductor crimping portion.

[0014] It is desirable that the plate thickness of the terminal is greater than 0.3 mm.

[0015] It is desirable that the compression ratio of the conductor crimped portion be 65% or more.

[0016] The butt portion on the inner surface of the conductor crimping portion A weld bead with a gentle uneven shape is formed. It is desirable.

[0017] The tension member may be made of a plurality of wires.

[0018] The conductive wire may be twisted around the outer periphery of the strength member.

[0019] At least the tip of the conducting wire may be compressed from the outer periphery.

[0020] The conductive wire may be subjected to a plating treatment.

[0021] It is desirable that the conductor crimping portion does not come into contact with the strength member.

[0022] According to the first aspect of the present invention, the conductor crimping portion is formed into a generally tubular shape by rolling the ends of a flat plate-shaped material so that they butt together, and at least a portion of the butt joint is welded, so that the conductor can be crimped from the entire circumference in the conductor crimping portion. This makes it possible to prevent local stress from being generated in the conductor during crimping, and ensures a sufficient contact area between the conductor and the conductor crimping portion.

[0023] In addition, by welding the butt joint of the conductor crimping portion, unevenness is formed on the inner surface of the conductor crimping portion due to the weld bead. Therefore, even with weak compression, this unevenness contributes to an increase in the contact area with the conductor and an increase in the pull-out resistance, so that both connection strength and connection resistance can be achieved. The above-mentioned effect is particularly effective when using a thin coated conductor with a cross-sectional area of ​​0.3 sq. or less.

[0024] Furthermore, if the inner area of ​​the weld bead at the butt portion on the inner surface of the conductor crimping portion is greater than 20% of the total inner surface area of ​​the conductor crimping portion, the above-mentioned effects can be obtained more efficiently.

[0025] Also, to increase the tensile strength of the connection, it is preferable for the terminal to be thick. However, particularly in the case of small-diameter terminals, when the terminal is thick, the strength of the crimping blade tends to be insufficient, and when the electric wire is strongly compressed, the strength of the blade is not sufficient, so there is a problem that it is not possible to crimp strongly. For this reason, when the terminal is thick, it is necessary to perform crimping under conditions of high compression ratio (conditions of looser compression). As a result, this can cause the electric wire to come loose and also tends to increase the electrical resistance.

[0026] In contrast, the uneven shape of the weld bead ensures a large contact area between the conductor crimping portion and the conductor and increases the pull-out resistance, making it possible to achieve both connection strength and connection resistance even when the terminal plate thickness is greater than 0.3 mm or the compression rate of the conductor crimping portion is 65% or more.

[0027] Furthermore, if the height of the unevenness of the weld bead at the butt portion on the inner surface of the conductor crimping portion is 50 μm or more, the unevenness increases the contact area with the conductor and increases the pull-out resistance.

[0028] Furthermore, if the strength member is made of a plurality of wires, the wires will form irregularities on the outer periphery of the strength member during compression, and therefore, even if the conductor is deformed by the same amount, part of the conductor can enter the irregularities and deform, which can prevent the conductor from being crushed too much, compared to when the conductor is deformed on the outer periphery of a single strength member.

[0029] Furthermore, if the conductor wires are twisted around the outer periphery of the tension member, the conductor wires can be prevented from becoming unraveled.

[0030] Similarly, by compressing the tip of the conductor from the outer periphery to form a terminal processing portion, it is possible to prevent the conductor from coming apart when the tip of the conductor is inserted into the tubular conductor crimping portion.

[0031] In addition, plating the surface of the conductor with a conductive metal is effective in improving conductivity and tensile strength. It also has the effect of improving workability by reducing the variation of the conductor wire during crimping. Furthermore, if the hardness of the plating is smaller than that of the conductor, the unevenness of the weld bead can be more easily embedded.

[0032] Furthermore, by crimping the conductor crimping portion so that it does not come into contact with the tensile member, it is possible to prevent the conductor from being distorted in its arrangement, ensure that the conductor and the conductor crimping portion are in contact with each other, and ensure that the conductor and the tensile member are compressed.

[0033] A second aspect of the present invention is a wire harness comprising a plurality of electric wires with terminals, including the electric wire with terminal according to the first aspect of the present invention, integrated together.

[0034] According to the second aspect of the present invention, a wire harness in which a plurality of small diameter electric wires are bundled can be obtained.

[0035] The third invention is The coated conductor wire and the terminal are electrically connected A method for producing an electric wire with a terminal, comprising the steps of: The coated conductor has a tension member, a conductor, and a coating portion that coats the tension member and the conductor, and the cross-sectional area of ​​the conductor is 0.3 sq. or less. The terminal includes a conductor crimping portion to which the conductor exposed from the coating portion at the tip of the coated conductor is crimped, and a coating crimping portion to which the coating portion of the coated conductor is crimped, and the conductor crimping portion is a flat plate-shaped The material is rolled and the ends are butted together, and the gap between the ends is made equal to or less than the plate thickness. At least a part of The conductor crimping portion is laser welded to Roughly tubular In forming the electric wire with terminal, a laser passes through the gap in the butt joint to form an opposing surface weld mark on the inner surface of the conductor crimping portion on the opposing surface side of the butt joint, and the conductor is inserted into the conductor crimping portion to crimp the conductor from all around the conductor. This is a method for manufacturing an electric wire with terminal, characterized in that

[0036] According to the third aspect of the present invention, when welding the butt portions, welding marks are also formed on the inner surface of the opposing surface of the terminal, so that the unevenness of the welding marks on the opposing surface can also be utilized. Effect of the Invention

[0037] According to the present invention, it is possible to provide an electric wire with a terminal that is capable of achieving both connection strength and connection resistance. [Brief description of the drawings]

[0038] [Figure 1] FIG. 2 is a perspective view showing a terminal-fitted electric wire 10. [Diagram 2] FIG. 2 is an axial cross-sectional view showing the electric wire with terminal 10. [Diagram 3] 3A is a radial cross-sectional view of the conductor crimping portion 7, taken along line AA in FIG. 2, and FIG. 3B is an enlarged view of part D in FIG. [Figure 4] 5 is a partial enlarged view of the inner surface side of the conductor crimping portion 7, taken along the line G in FIG. [Diagram 5] 4A to 4C are diagrams showing a process of forming a conductor crimping portion 7. [Figure 6] 13(a) and (b) are radial cross-sectional views showing a step of forming a conductor crimping portion 7, and (c) is a diagram showing another method. [Figure 7] A diagram showing the terminal 1 and the coated conductor wire 11 before crimping. [Figure 8] 1A is a diagram showing the tip of a conductive wire 13, and FIGS. 1B to 1D are diagrams showing the form of a terminal processing portion 19. FIG. [Figure 9] 4(a) to 4(b) are schematic diagrams showing a bonding process. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0039] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a perspective view showing an electric wire with terminal 10, Fig. 2 is an axial cross-sectional view of the electric wire with terminal 10, and Fig. 3(a) is a cross-sectional view taken along line AA in Fig. 2. The electric wire with terminal 10 is configured by electrically connecting a terminal 1 and a coated conductor wire 11.

[0040] The coated conductor wire 11 is composed of a tension member 17 (see FIG. 3(a)), a conductor wire 13, and a coating 15 that coats the tension member 17 and the conductor wire 13. That is, the coated conductor wire 11 includes the coating 15 and the conductor wire 13 exposed from its tip. The conductor wire 13 may be, for example, a soft copper wire, a hard copper wire, a copper alloy wire, an aluminum wire, an aluminum alloy wire, or the like, although a soft copper wire is preferable from the viewpoint of electrical conductivity.

[0041] The terminal 1 is made of, for example, copper, a copper alloy, aluminum, or an aluminum alloy. A covered conductor wire 11 is connected to the terminal 1. The terminal 1 is configured by connecting a terminal body 3 and a crimping portion 5 via a transition portion 4.

[0042] The terminal body 3 is a plate material of a predetermined shape formed into a cylinder with a rectangular cross section. The terminal body 3 has an elastic contact piece formed by folding the plate material into the rectangular cylinder inside. The terminal body 3 is connected by inserting a male terminal or the like from the front end. In the following description, an example is shown in which the terminal body 3 is a female terminal that allows the insertion of an insertion tab (not shown) of a male terminal or the like, but the detailed shape of the terminal body 3 is not particularly limited in the present invention. For example, an insertion tab of a male terminal may be provided instead of the female terminal body 3, or a bolt fastening portion like a round terminal may be provided.

[0043] The crimping portion 5 of the terminal 1 is a portion that is crimped to the covered conductor wire 11, and includes a conductor crimping portion 7 that crimps the conductor wire 13 exposed from the coating portion 15 at the tip side of the covered conductor wire 11, and a coating crimping portion 9 that crimps the coating portion 15 of the covered conductor wire 11. That is, the conductor wire 13 exposed when the coating portion 15 is peeled off is crimped by the conductor crimping portion 7, and the conductor wire 13 and the terminal 1 are electrically connected. Also, the coating portion 15 of the covered conductor wire 11 is crimped by the coating crimping portion 9 of the terminal 1.

[0044] The coating crimping portion 9 is a so-called open barrel type. The conductor crimping portion 7 is configured in a tubular (approximately cylindrical) shape that is closed in the circumferential direction. That is, the conductor crimping portion 7 is formed into a substantially tubular shape by rolling the ends of a flat plate-shaped material so that they butt together, and at least a part of the butt joint is welded, and a weld bead 23 is formed at the welded butt joint. The coating crimping portion 9 may also be tubular like the conductor crimping portion 7.

[0045] As shown in Fig. 3(a), the covered conductor wire 11 has a tension member 17 disposed substantially in the center of the cross section, and a conductor wire 13 made of a plurality of conductors disposed on the outer periphery of the tension member 17. The tension member 17 is a member that receives tension in response to a tensile load. The tension member 17 is preferably made of a plurality of strands. Furthermore, on the outer periphery of the tension member 17, the conductor wire 13 may be twisted in a spiral shape in the longitudinal direction of the covered conductor wire 11.

[0046] As described above, the conductor crimping portion 7 is tubular. Therefore, at a predetermined position in the axial direction of the conductor crimping portion 7 (cross section at a predetermined position), the conductor 13 can be crimped from its entire circumference of 360° by the conductor crimping portion 7. That is, the conductor 13 is crimped from the entire circumference in the circumferential direction of the conductor 13 by the conductor crimping portion 7. Therefore, the inner surface of the conductor crimping portion 7 comes into contact with the conductor 13 over the entire circumference, and it is possible to suppress local stress (deformation) occurring in the conductor 13 during crimping.

[0047] As described above, the conductor crimping portion 7 has a butt portion welded to form a weld bead 23. FIG. 3(b) is an enlarged view of portion D in FIG. 3(a). The conductor crimping portion 7 is welded, for example, by laser welding. Here, the weld bead 23 is formed in a gentle uneven shape in the circumferential and longitudinal directions on the inner surface side of the conductor crimping portion 7. Such an uneven shape on the inner surface of the conductor crimping portion 7 contributes to increasing the area where the conductor 13 and the conductor crimping portion 7 get caught. Therefore, even when crimping is performed under conditions of particularly weak compression, it is possible to prevent the electric wire from being pulled out, and the uneven shape can have the effect of destroying the oxide film.

[0048] Serrations (not shown) may be provided in the circumferential direction (direction perpendicular to the longitudinal direction) on a part of the inner surface of the conductor crimping portion 7. By forming the serrations in this manner, the oxide film on the surface of the conductor 13 can be easily destroyed when the conductor 13 is crimped, and the contact area with the conductor 13 can be increased.

[0049] Normally, the width of the recesses of the serrations is wide, and they are effective with a relatively large amount of compression. Also, since the serrations are shaped along the circumferential direction, they do not have an uneven shape in the circumferential direction, and in the case of a thin-diameter conductor 13, there is a risk of damage at the steps (edges) of the serrations. In contrast, by forming small, gentle unevenness in the circumferential and longitudinal directions, as in the weld bead 23, it is possible to prevent the electric wire from being pulled out even with a small amount of compression, and the uneven shape is also expected to have an effect of destroying the oxide film.

[0050] In order to obtain the above-mentioned effects more reliably, it is desirable that the area of ​​weld bead 23 at the butt portion on the inner surface of conductor crimping portion 7 be larger than 20% of the total inner surface area of ​​conductor crimping portion 7. Fig. 4 is a view taken along arrow G in Fig. 3(b), and is a partial conceptual diagram seen from the inner surface side of conductor crimping portion 7 with conductor 13 seen through.

[0051] 2, if the overall length of the conductor crimping portion 7 in the longitudinal direction of the terminal is C, the vicinity of both longitudinal ends may be tapered so that the amount of compression decreases toward the ends to avoid sudden deformation. In this case, the length actually crimped at a predetermined compression rate (B in the figure) is defined as the crimping portion length of the conductor crimping portion 7.

[0052] That is, the area S1 of weld bead 23 at the butt portion on the inner surface of conductor crimping portion 7 is calculated as length B x width (average width) H in Fig. 4. The total inner surface area S2 of conductor crimping portion 7 is calculated as length B x diameter E (Fig. 3(a)) x π. In this case, it is desirable that S1 / S2 (%) > 20%. By doing so, the unevenness effect caused by weld bead 23 can be obtained more reliably.

[0053] It is also desirable that the unevenness height of weld bead 23 at the butt portion on the inner surface of conductor crimping portion 7 is 50 μm or more. Here, the unevenness height of weld bead 23 refers to the maximum convex height toward the inner surface (F in the figure) in the crimping range when an extension line of the portion other than weld bead 23 is used as a reference, as shown in Fig. 3(b). By doing so, the unevenness effect of weld bead 23 can be obtained more reliably.

[0054] Here, this embodiment is particularly effective when the cross-sectional area of ​​the conductor 13 (total cross-sectional area of ​​the wires) is 0.3 sq. or less. As described above, when a large-diameter covered conductor is used to connect to a crimp terminal, it is easy to perform crimping at the conductor crimping portion with a compression ratio that satisfies both connection strength and connection resistance, but when the diameter is small, it is difficult to control the balance between conductivity and tensile strength with the compression ratio alone. For this reason, it becomes more important to prevent the electric wire from being pulled out, especially when the compression ratio is 65% or more.

[0055] Since the conductor 13 is used together with the tensile member 17, the cross-sectional area of ​​the conductor 13 may be 0.05 sq or less. The smaller the cross-sectional area of ​​the conductor 13, the greater the effect of this embodiment. From the viewpoint of ensuring the crimping strength, the cross-sectional area of ​​the conductor 13 is preferably 0.01 sq or more, and more preferably 0.03 sq or more.

[0056] The tension member 17 may be a metal wire such as a steel wire, or may be made of resin or fiber-reinforced resin, but is made by bundling a number of strands. For example, the strands constituting the tension member 17 may be made of PBO (polyparaphenylene benzobisoxazole) fiber, aramid fiber, carbon steel wire, stainless steel wire, liquid crystal polyester fiber, etc., but non-metallic wires are preferable in terms of corrosion resistance.

[0057] Furthermore, it is desirable that the tensile strength of the tension member 17 is higher than that of the conductor 13. Note that, although tensile strength refers to the maximum stress that leads to breakage when subjected to tensile stress, in this embodiment, it is taken as a relative index of the ease of breakage due to crushing of the material during crimping. In other words, the tension member 17 is made of a material that is less likely to deform during crimping compared to the conductor 13. Note that, further, it is desirable that the Young's modulus of the tension member 17 is higher than that of the conductor 13, and the yield stress (or proof stress) of the tension member 17 is higher than the yield stress (or proof stress) of the conductor 13.

[0058] Next, a method for manufacturing the electric wire with terminal 10 will be described. Fig. 5 is a perspective view showing the step of forming the conductor crimping portion 7 of the terminal 1 before crimping. As described above, the terminal 1 has the terminal body 3 and the crimping portion 5, and the crimping portion 5 is composed of the conductor crimping portion 7 and the insulation crimping portion 9. The conductor crimping portion 7 is formed by rolling a plate-shaped material, butting the ends together, and welding the butted portion in the longitudinal direction, for example, with a laser 27.

[0059] 6(a) is a cross-sectional view when welding butt joint 25. A gap is formed in butt joint 25. The gap in butt joint 25 is desirably equal to or smaller than the plate thickness of terminal 1. If a gap equal to or larger than the plate thickness is formed, the amount of metal melted by welding butt joint 25 will be smaller than the spatial volume of the gap, making it difficult to completely seal the gap by welding.

[0060] 6(b) is a cross-sectional view of the conductor wire crimping portion 7 after laser welding. As described above, a weld bead 23 is formed at the butt joint. At this time, it is desirable that the area of ​​the weld bead 23 on the inner surface of the butt joint of the terminal is greater than 20% of the inner area of ​​the terminal. For this reason, it is desirable to use laser welding, which allows the bead width to be variable.

[0061] When the conductor wire has a large diameter, the diameter of the laser welding spot is relatively much smaller than the inner diameter of the terminal. Therefore, the relative area of ​​the weld bead width is smaller than the inner area of ​​the terminal. On the other hand, when the cross-sectional area of ​​the conductor wire 13 (total cross-sectional area of ​​the wires) is small, 0.3 sq. or less, the diameter of the laser welding spot is relatively large compared to the inner diameter of the terminal, so the bead width area can be increased.

[0062] Although the gap in butt joint 25 before welding may be eliminated and the joints may be in contact with each other (i.e., the gap is 0 mm), it is preferable to have a gap that allows a part of laser 27 to pass through as long as the weldability of butt joint 25 is not impaired, as shown in Fig. 6(a). When butt joint 25 is laser-welded with a gap to form cylindrical conductor crimping portion 7, laser 27 that passes through the gap in butt joint 25 forms opposing surface weld mark 23a on the inner surface of conductor crimping portion 7 on the opposing surface side of butt joint 25. Since opposing surface weld mark 23a also forms a fine uneven shape on the inner surface of conductor crimping portion 7, the same effect as weld bead 23 can be obtained.

[0063] That is, a gap is formed in the butt joint 25 of the terminal 1 before welding, and the laser 27 that passes through the butt joint 25 creates unevenness due to welding on the inner surface of the terminal on the opposite side of the butt joint 25, thereby increasing the area where the conductor 13 gets caught compared to when there is no gap. This makes it possible to better prevent the wire from being pulled out, especially under manufacturing conditions with weak compression. In this way, it is desirable for the gap at the butt joint 25 during welding to be greater than 0 mm (and more desirably greater than 50 μm) and less than the plate thickness.

[0064] As a method for controlling the gap at the butt joint 25, as shown in Fig. 6(c), welding may be performed while both sides of the conductor crimped portion 7 before welding are held down by a holding jig 29. For example, when the conductor crimped portion is rounded by a die, a gap is created by springback. Therefore, welding can be performed with a specified gap by pushing back the shape that has returned to its original shape by springback.

[0065] 7, the coating 15 at the tip of the coated conductor wire 11 is stripped to expose the conductor wire 13 at the tip, which is then inserted into the crimping portion 5. Before being inserted into the crimping portion 5 of the terminal 1, the tip of the conductor wire 13 may be subjected to terminal processing.

[0066] 8(a) is a diagram showing a state in which an end processing section 19 is formed at the tip of the conductor wire 13. The end processing section 19 is a processing section that integrates the individual wires of the conductor wire 13 so that they do not come apart.

[0067] As described above, the tensile member 17 is disposed approximately in the center, and the conductor wire 13 is disposed on its outer periphery. The conductor wire 13 is made of a plurality of conductors. In such a case, as shown in FIG. 8(b), at least the tip of the conductor wire 13 can be compressed from the outer periphery to form the end processing portion 19. In this way, by compressing the tip of the conductor wire 13 from the outer periphery, the wire is prevented from coming apart, and it is easy to insert the conductor wire into the tubular crimping portion 5.

[0068] 8(c), at least the tip of the conductor 13 may be plated all at once to form the end processing portion 19 with the plating layer 21. By plating the tip of the conductor 13 all at once from the outer periphery in this manner, the wire is prevented from coming apart, and it is easy to insert the wire into the tubular crimping portion 5.

[0069] Depending on the plating method, high temperatures may be generated when plating is performed all at once from the outer periphery of the conductor 13. If plating is performed all at once after twisting the conductor 13 using such a plating method, the tensile member 17 may be deteriorated by the heat, resulting in a decrease in tensile strength.

[0070] In such a case, as shown in FIG. 8(d), a plating layer 21 may be formed for each conductor and then twisted around the outer periphery of the tension member 17. Alternatively, a plating layer 21 may be formed for each conductor, and the tips of the conductors may be plated together from the outer periphery. In this case, the type of plating for each conductor may be different from the type of plating for all conductors. As described above, by performing plating at the same time, it is possible to prevent the conductors from coming apart, but if the conductors are bundled and plated at the same time, there is a risk that some parts may be thick or thin due to the influence of the conductor shape, etc. In response to this, by performing a base plating treatment for each conductor in advance, this influence can be reduced and approximately uniform plating can be achieved at the same time.

[0071] In addition, by forming a plating layer 21 that is softer than the conductor wire 13, the synergistic effect with the unevenness of the weld bead 23 described above prevents the wire from being pulled out under conditions of weaker compression and increases the tensile strength.

[0072] The terminal processing section 19 is not limited to the method using compression or plating, and may be, for example, soldering or welding the tip of the conductor wire 13 to suppress the stranding of the wire. Also, a combination of multiple terminal processing methods, such as compression from the periphery and collective plating, may be used.

[0073] Next, the coated conductor wire 11 whose tip has been treated in this manner is inserted from the rear end side of the tubular crimping portion 5 of the terminal 1. When the tip of the coated conductor wire 11 is inserted into the crimping portion 5, the exposed portion of the conductor wire 13 is located inside the conductor crimping portion 7, and the coating portion 15 is located inside the coating crimping portion 9. At this time, the tip of the conductor wire 13 may protrude from the tip of the conductor crimping portion 7.

[0074] 9(a) is a cross-sectional view showing the upper blade die 31a, the lower blade die 31b, etc. before crimping the terminal crimping blade die for manufacturing the electric wire with terminal 10, and FIG. 9(b) is a cross-sectional view showing the crimping portion 5 during crimping. The upper blade die 31a and the lower blade die 31b have a substantially semi-cylindrical cavity extending in the longitudinal direction. The upper blade die 31a includes a coating crimping blade die 34 corresponding to the coating crimping portion 9 and having a diameter slightly smaller than the radius of the coating crimping portion 9, and a conductor crimping blade die 32 corresponding to the conductor crimping portion 7 and having a diameter smaller than that of the coating crimping blade die 34. That is, the upper blade die 31a and the lower blade die 31b are formed so that both the portions corresponding to the conductor crimping portion 7 and the coating crimping portion 9 have a substantially circular cross section when the terminal 1 is crimped.

[0075] As shown in FIG. 9(b), when the upper blade die 31a and the lower blade die 31b are engaged to compress the crimping portion 5, the conductor crimping portion 7 is crimped to the conductor 13, and the coating crimping portion 9 is crimped to the coating portion 15. In the longitudinal cross section of the conductor crimping portion 7, the conductor crimping blade die 32 has a straight portion in the approximate longitudinal center, and both ends are tapered. That is, the conductor crimping portion 7 is compressed at an approximately constant compression rate near the longitudinal center, and both ends are gradually compressed to a smaller amount. In this case, the crimping portion length B of the conductor crimping portion 7 is the length of the cross-sectional straight portion compressed at a constant compression rate, relative to the length C of the conductor crimping portion 7.

[0076] In this manner, it is possible to obtain the electric wire with terminal 10. Furthermore, it is possible to obtain a wiring harness in which a plurality of electric wires with terminals, including the obtained electric wire with terminal 10, are integrated together.

[0077] Here, the compression ratio of the conductor crimping portion is desirably 65% ​​or more. Even if the compression ratio is 65% or more, the uneven shape of the weld bead 23 described above improves the tensile strength and reduces the crimping resistance between the terminal and the electric wire. The compression ratio of the conductor crimping portion 7 is expressed as follows: compression ratio of conductor crimping portion 7 = A1 / A0 (%), where A0 is the total cross-sectional area of ​​conductor 13 before the crimping process, and A1 is the total cross-sectional area of ​​conductor 13 at conductor crimping portion 7 after being compressed by upper blade die 31a and lower blade die 31b.

[0078] In addition, since the strength of the tension body 17 is high and it is difficult to deform compared to the conductor 13, the cross-sectional area of ​​the tension body 17 does not decrease significantly during compression, and mainly the deformation (reduction in cross-sectional area) of the conductor 13 progresses. Here, as described above, the conductor 13 is crimped from the entire circumference of the conductor 13 in the circumferential direction at the conductor crimping portion 7. In addition, since the tension body 17 is formed by a plurality of tension body wires, unevenness is formed on the outer periphery of the tension body 17 (region). Therefore, at the interface between the tension body 17 and the conductor 13, the conductor 13 deforms according to the unevenness caused by the tension body wires. The uneven outer shape of the tension body 17 increases the contact area between the conductor 13 and the tension body 17, and the frictional force increases. Therefore, it becomes easier for the force to be transmitted from the conductor 13 to the tension body 17 when tension is applied, and an increase in strength can be expected when tension is applied to the conductor 13.

[0079] For example, if the strength member 17 is a solid wire, the interface between the strength member 17 and the conductor 13 is almost smooth. At this time, the strength member 17 is difficult to deform relative to the conductor 13, so the conductor 13 deforms by being crushed along the surface of the strength member 17. This may cause the conductor 13 to become too thin and break. In contrast, if the outer peripheral surface of the strength member 17 is uneven, the conductor 13 can deform to fit into the unevenness, so it is not crushed excessively and breakage can be suppressed.

[0080] In addition, since the amount of deformation of the tension member 17 is smaller than that of the conductor 13, breakage due to a reduction in cross-sectional area is unlikely to occur. In particular, since the conductor crimping portion 7 is tubular, the conductor 13 is compressed from the entire circumference, and the tension member 17 is disposed between the conductor crimping portion 7 and the tension member 17 does not come into contact with the conductor crimping portion 7, so that the tension member 17 is not damaged.

[0081] During compression, some of the wires constituting the tension member 17 may get between the conductor wires 13, causing part of the tension member 17 to come into contact with the conductor crimping portion 7. To ensure a sufficient conduction area between the conductor wires 13 and the conductor crimping portion 7, it is desirable that the tension member 17 and the conductor crimping portion 7 do not come into contact with each other.

[0082] Furthermore, increasing the area of ​​weld bead 23 also increases the area where strength is reduced by weld bead 23. For this reason, in order to maintain sufficient strength after welding, it is desirable for the plate thickness of the terminal to be thicker than 0.3 mm. Thus, in order to increase the tensile strength of the connection, it is usually preferable for the plate thickness of the terminal to be thicker.

[0083] Here, usually, especially in the case of a terminal with a small diameter, when the plate thickness of the terminal is increased, the strength of the crimping blade is insufficient, and when the electric wire is strongly compressed, the strength of the blade is not sufficient, so there is a problem that strong crimping is not possible. For this reason, when the plate thickness is increased, it is necessary to perform crimping under conditions of high compression ratio (conditions of weaker compression). As a result, it tends to cause the electric wire to come loose and also increases the electrical resistance. However, in this embodiment, the uneven shape of the weld bead 23 improves the tensile strength, so that the tensile strength can be ensured even under conditions of high compression ratio.

[0084] As described above, according to this embodiment, the conductor 13 is crimped from all directions of 360° around the conductor 13 in the conductor crimping section 7, so that it is possible to suppress local stress (deformation) from occurring in the conductor 13 during crimping. Furthermore, it is possible to crimp the conductor 13 without significantly destroying the structure of the central tensile member 17 and the conductor 13 twisted around it during crimping. Furthermore, since the conductor crimping section 7 comes into contact with the conductor 13 all around, it is also possible to suppress deterioration of resistance.

[0085] In addition, since an uneven shape is formed on the inner surface side of weld bead 23, the area where conductor wire 13 gets caught increases, making it possible to prevent the electric wire from being pulled out. In particular, even in a range of conditions where compression is weak (compression rate of 65% or more), it is possible to achieve both tensile strength and connection resistance.

[0086] This effect is particularly effective when the height of the unevenness on the inner surface of weld bead 23 is 50 μm or more and the inner area of ​​weld bead 23 is greater than 20% of the total inner surface area of ​​conductor crimping portion 7. For this reason, this is particularly effective for thin electric wires of 0.3 sq or less, for which it is difficult to achieve both low connection resistance and high tensile strength with only the compression ratio.

[0087] Furthermore, by forming opposing surface weld marks 23a separately from weld beads 23, the unevenness of opposing surface weld marks 23a can be utilized in addition to the unevenness of weld bead 23. EXAMPLES

[0088] Various types of electric wires with terminals were prepared, and the electrical properties (resistance performance of the crimped part) and mechanical properties (tensile strength performance) of the crimped part were evaluated. The terminals used had a tubular crimped part (see Figure 7). The inner diameter of the crimped part of the conductor was 0.45 mm, and the crimped length of the crimped part of the conductor was 4 mm (B in Figure 9(b)).

[0089] The coated conductors all had a tension member placed in the center of the cross section, with the conductor wires twisted together around the outside and tin-plated (see Figure 8(d)). The cross-sectional area of ​​the conductor, which is the total cross-sectional area of ​​the conductor, was 0.05 sq. for all wires. The conductor materials were soft copper wire and PBO fiber. The tensile strength of the soft copper wire was 234 MPa, and the tensile strength of the tension member was 4400 MPa.

[0090] The electrical properties were evaluated by measuring the electrical resistance between the terminal and the coated conductor. The mechanical properties were evaluated by pulling the coated conductor from the terminal and measuring the tensile strength based on the load applied when the coated conductor was pulled out. The conditions and results are shown in Tables 1 and 2.

[0091] [Table 1]

[0092] [Table 2]

[0093] In the table, "butt gap" refers to the gap when the conductor crimped portion is laser welded into a tubular shape. The gap at the butt was determined using a microvice. Gaps less than 10 μm were determined to be non-existent. The presence or absence of welding marks on the opposing surfaces refers to the presence or absence of welding marks on the opposing surfaces of the weld bead when the laser passes through the gap during welding, and the area ratio of the welding marks on the opposing surfaces was calculated in the same way as the inner area of ​​the weld bead.

[0094] The crimped part resistance is the electrical resistance between the tip of the terminal and the rear end of a 100mm long covered conductor. A crimped part resistance of less than 2mΩ is marked as "Good", and 2mΩ or more is marked as "Poor". The tensile strength is the load applied when the covered conductor is pulled out from the terminal. Tensile strength performance is marked as "Good" for 50N or more, and "Poor" for less than 50N.

[0095] As can be seen from Tables 1 and 2, in Examples 1 to 6, in which the weld bead inner area / total inner area ratio exceeded 20%, both the crimped portion resistance performance and the tensile strength performance were acceptable, even though the compression ratio was 65% or more in all cases.

[0096] On the other hand, in Comparative Example 1, the gap during welding was too large, resulting in poor penetration during welding. As a result, part of the conductor protruded from the gap, and both the resistance performance and the tensile strength performance of the crimped portion were unacceptable. In Comparative Example 2, the area ratio of the weld bead was small, and the effect of the weld bead was small, so the tensile strength performance was unacceptable. In Comparative Example 3, the terminal plate thickness was thin, so the conductor crimped portion broke during crimping. As a result, both the resistance performance and the tensile strength performance of the crimped portion were unacceptable.

[0097] Although the embodiment of the present invention has been described above with reference to the attached drawings, the technical scope of the present invention is not limited to the above-described embodiment. It is clear that a person skilled in the art can think of various modifications or alterations within the scope of the technical ideas described in the claims, and it is understood that these also naturally belong to the technical scope of the present invention.

[0098] For example, in the above description, an example was shown in which the conductor 13 is arranged in one layer around the outer periphery of the strength member 17, but the arrangement of the conductor 13 is not limited to this. As long as the conductor 13 is arranged on the outer periphery side of the strength member 17, the conductor 13 may be arranged in two layers around the strength member 17, or the conductor 13 may be arranged in three layers around the strength member 17.

[0099] In the above description, an example has been described in which the tensile body 17 is made up of a plurality of tensile body wires. However, even if the tensile body 17 is a solid wire, it may be a solid wire as long as its external shape can be deformed together with the conductor 13 when compressed and an uneven shape is formed on the outer periphery after compression. [Explanation of symbols]

[0100] 1...Terminal 3: Terminal body 4. Transition section 5……… Crimping section 7………Conductor crimping section 9......Sheathing crimping part 10...Terminal wire 11....Coated conductor 13……Conducting wire 15....Covering part 17……Tensile strength body 19... Terminal processing section 21: Plating layer 23... Weld bead 23a………Welding marks on opposing surfaces 25………Butt joint 27...Laser 29....Pressing jig 31a……Top blade type 31b……Lower blade type 32………Conductor crimping blade type 34……Coated crimp blade type

Claims

1. A terminal-attached electric wire in which a coated conductor wire and a terminal are electrically connected, The covered conductor wire includes a tension member, a conductor wire, and a covering portion that covers the tension member and the conductor wire, The cross-sectional area of ​​the conductor is 0.3 sq. or less, The terminal includes a conductor crimping portion to which the conductor exposed from the coating portion at the tip of the coated conductor is crimped, and a coating crimping portion to which the coating portion of the coated conductor is crimped, The conductor crimping portion is formed in a generally tubular shape having a weld bead formed by rolling ends of a flat plate-shaped material so that the ends are butted together, and at least a portion of the butt joint is welded. A facing surface weld mark is formed on the inner surface of the conductor crimping portion on the facing surface side of the butt joint, separately from the weld bead. The electric wire with terminal, wherein the conductor is crimped at the conductor crimping portion from all around the conductor in a circumferential direction.

2. 2. The electric wire with terminal according to claim 1, wherein an area of ​​the weld bead of the butt portion on the inner surface of the conductor crimping portion is greater than 20% of a total inner surface area of ​​the conductor crimping portion.

3. 3. The electric wire with terminal according to claim 1, wherein the terminal has a plate thickness of more than 0.3 mm.

4. 4. The electric wire with terminal according to claim 1, wherein the conductor crimped portion has a compression ratio of 65% or more.

5. 5. The electric wire with terminal according to claim 1, wherein a weld bead having a gently undulating shape is formed on the butted portion on the inner surface of the conductor crimping portion.

6. The electric wire with terminal according to any one of claims 1 to 5, wherein the tension member is made of a plurality of wires.

7. 7. The electric wire with terminal according to claim 1, wherein the conductor is twisted around an outer periphery of the tension member.

8. The electric wire with terminal according to any one of claims 1 to 7, characterized in that at least a tip portion of the conductor is compressed from an outer periphery side.

9. The electric wire with terminal according to any one of claims 1 to 8, wherein the conductor wire is plated.

10. 10. The electric wire with terminal according to claim 1, wherein the conductor crimping portion does not contact the tension member.

11. A wire harness comprising a plurality of electric wires with terminals, the electric wire with terminal being the electric wire according to any one of claims 1 to 10, integrated together.

12. A method for producing a terminal-equipped electric wire in which a coated conductor wire and a terminal are electrically connected, comprising the steps of: The covered conductor wire includes a tension member, a conductor wire, and a covering portion that covers the tension member and the conductor wire, The cross-sectional area of ​​the conductor is 0.3 sq. or less, The terminal includes a conductor crimping portion to which the conductor exposed from the coating portion at the tip of the coated conductor is crimped, and a coating crimping portion to which the coating portion of the coated conductor is crimped, The conductor crimping portion is formed by rolling a flat plate-shaped material, butting ends together, and laser-welding at least a portion of the butt joint so that the gap between the ends is equal to or smaller than the plate thickness, and forming a generally tubular conductor crimping portion by laser-welding at least a portion of the butt joint, and forming an opposing surface weld mark on the inner surface of the conductor crimping portion on the opposing surface side of the butt joint with a laser that passes through the gap in the butt joint; A method for manufacturing an electric wire with a terminal, comprising inserting the conductor into the conductor crimping portion and crimping the conductor from the entire circumferential direction.

Images