JP5786590B2 - Electric wire, electric wire with terminal fittings, and method of manufacturing electric wire with terminal fittings - Google Patents

Description

  The present invention relates to an electric wire, an electric wire with a terminal fitting, and a connection method between the terminal fitting and the electric wire.

  2. Description of the Related Art Conventionally, as a method for connecting an aluminum electric wire in which a core wire made of an aluminum core material is covered with an insulating coating and a terminal fitting, for example, one described in Patent Document 1 below is known. Aluminum wires are easily formed with an oxide film on the surface of the core material. In order to destroy the oxide film, serrations are formed on the crimping portion of the terminal fitting, and the oxide film formed on the surface of the aluminum wire is serrated. It is being destroyed. By doing so, the aluminum core material is exposed by breaking the oxide film, and at the same time, the core material is connected to the crimping portion so as to be conductive, so that the electrical connection resistance between the aluminum wire and the terminal fitting is reduced. be able to.

JP 2010-3584 A

  However, in the above connection method, serrations cannot be brought into contact with the inside of the core wire, so that the electrical connection resistance cannot be reduced between the strands constituting the core wire. This is particularly noticeable in the case of a large-diameter electric wire with a large number of strands, and a stable electrical connection resistance cannot be obtained. However, even if the crimping portion is caulked strongly, the terminal fitting may be damaged, or the crimping portion may extend and the crimping portion may protrude from the rear end of the connector. Thus, there has been a strong demand for a connection method that can obtain a stable electrical connection resistance even under mild pressure bonding conditions.

  The present invention has been completed based on the above-described circumstances, and an object thereof is to obtain a stable electrical connection resistance under mild pressure bonding conditions.

  The present invention is an electric wire connected to a terminal fitting by crimping, comprising a core wire formed by bundling a plurality of strands in which an aluminum layer or an aluminum alloy layer is formed on the surface layer of the core material, and a pair of adjacent strands At least one of them is characterized in that a hard layer harder than the core material is formed on the surface of the aluminum layer or aluminum alloy layer.

  Moreover, this invention is good also as an electric wire with a terminal metal fitting provided with said electric wire and the terminal metal fitting which has a crimping | compression-bonding part crimped | bonded to the core wire of this electric wire.

  In addition, the present invention is a method of connecting a terminal fitting and an electric wire for connecting a crimping portion provided on the terminal fitting to an electric wire having a core wire formed by bundling a plurality of strands, on the surface layer of the core material in the strand An aluminum layer or an aluminum alloy layer is formed, and a hard layer harder than the aluminum layer or the aluminum alloy layer is formed on at least one of the adjacent strands so as to cover the surface of the aluminum layer or the aluminum alloy layer. When the crimped part is deformed and crimped to the core wire, the hard layer is broken, and the broken hard layer scrapes the surface layer of the core material to expose the core material, and the exposed core materials are pressed together. May be.

  In this case, since the hard layer is harder than the core material, when the crimping portion of the terminal fitting is crimped to the core wire of the electric wire, the hard layer does not follow the deformation of the crimping portion, thereby easily breaking the hard layer. be able to. And since this fracture | ruptured hard layer breaks the oxide film formed in the surface of a strand, and exposes a core material, this exposed core materials can be connected so that conduction | electrical_connection is possible. Accordingly, it is possible to avoid the terminal fitting from being damaged or the crimping portion from protruding from the rear end of the connector by strongly caulking the terminal fitting as in the prior art. As a result, a stable electrical connection resistance can be obtained under mild pressure bonding conditions. Moreover, even when using a large-diameter electric wire, a stable electrical connection resistance can be obtained.

The following configuration is preferable as an embodiment of the present invention.
It is good also as a structure by which the hard layer is formed in all the strands.
According to such a configuration, since the hard layers come into contact with each other, the hard layers are easily broken.

A core material is good also as a structure which is the same metal material as an aluminum layer or an aluminum alloy layer, and makes one.
According to such a configuration, the core material and the aluminum layer or the aluminum alloy layer can be integrally formed.

The hard layer may be configured to be an alumite layer.
Since anodized is formed by forming an oxide film on the surface of aluminum or aluminum alloy, it is easy to form an alumite layer as a hard layer on the surface of the aluminum layer or aluminum alloy layer.

  According to the present invention, a stable electrical connection resistance can be obtained under mild pressure bonding conditions.

The top view of the terminal metal fitting in an embodiment Side view of terminal fitting Side view showing the state just before crimping the crimping part of the terminal fitting with the crimping die Side view showing the state immediately after crimping the crimping part of the terminal fitting with a crimping die Side view of electric wire with terminal bracket Sectional view showing the state of aluminum terminals and aluminum wires before crimping Sectional view showing the state of the aluminum terminal and aluminum wire after crimping Sectional view of the state immediately before crimping the crimping part of the aluminum terminal with the crimping die Cross-sectional view of the aluminum terminal crimping part viewed from the front during crimping with a crimping die Sectional view of the state immediately after crimping the crimping part of the aluminum terminal with a crimping die Sectional drawing which expanded and showed a part of FIG. Sectional drawing which expanded and showed a part of FIG. SEM image showing the crimping surface of the wire barrel when not anodized SEM image showing crimped surface of wire barrel when anodized The SEM image which shows the to-be-bonded surface of the core wire in FIG. The SEM image which shows the to-be-bonded surface of the core wire in FIG. Graph showing the data in Table 1 (without anodizing) Graph showing the data in Table 2 (with anodizing) Graph showing data in Table 3 (with sample No. 200 boehmite treatment) Graph showing data in Table 4 (with sample No. 210 boehmite treatment) Graph showing data in Table 5 (with sample No. 220 boehmite treatment)

<Embodiment>
An embodiment of the present invention will be described with reference to the drawings of FIGS. As shown in FIG. 1, the terminal fitting 12 before crimping includes a main body portion 20 having a rectangular tube shape and a crimp portion 30 formed at the rear of the main body portion 20. The terminal fitting 12 is an aluminum terminal formed by pressing a flat plate of an aluminum alloy as a base material (punching into a predetermined shape and further bending). More specifically, the base material is an aluminum alloy plate made of 6000 series alloy (corresponding to 6061 alloy) of JIS standard (JIS H 4000: 1999), for example, casting, hot rolling, cold rolling, and various Manufactured by a process called heat treatment (for example, T6 treatment). In the present embodiment, a female terminal fitting is exemplified as the terminal fitting 12, but according to the present invention, a male terminal fitting having a tab shape may be used. Moreover, as a base material of the terminal metal fitting 12, arbitrary metal materials, such as copper, a copper alloy, or aluminum, can be used.

  Aluminum alloys having a composition excellent in mechanical properties such as bending and heat resistance, specifically, 2000 series alloys, 6000 series alloys, and 7000 series alloys defined in JIS standards (JIS H 4000: 1999). Etc. can be used. The 2000 series alloy is an aluminum-copper series alloy called duralumin and super duralumin, and is excellent in strength. Specific alloy numbers include, for example, 2024 and 2219. The 6000 series alloy is an aluminum-magnesium-silicon series alloy and is excellent in strength, corrosion resistance, and anodic oxidation. Specific examples of the alloy number include 6061. The 7000 series alloy is an aluminum-zinc-magnesium series alloy called ultra-super duralumin, and has a very high strength. Specific examples of the alloy number include 7075.

  The covered electric wire 40 is an aluminum electric wire, and has a configuration in which a core wire 42 made of a plurality of metal wires 41 is covered with a covering 43 made of an insulating synthetic resin. The covered electric wire 40 of this embodiment is a bundle of 11 metal strands 41. As a core material of the metal strand 41 which comprises the core wire 42, arbitrary metal materials, such as copper, a copper alloy, aluminum, or an aluminum alloy, can be used. In addition, the metal strand 41 of this embodiment is comprised with the aluminum alloy. Thus, in this embodiment, it is set as the connection structure of the terminal metal fitting 12 which consists of aluminum alloys, and the core wire 42 which consists of aluminum alloys, ie, the connection structure which consists of the same kind of metal as a main component, There is virtually no electrical corrosion between them.

  The aluminum alloy constituting the covered electric wire is, for example, 0.005% by mass or more in total of one or more elements selected from iron, magnesium, silicon, copper, zinc, nickel, manganese, silver, chromium, and zirconium. 0.0% by mass or less, with the balance being aluminum and impurities. The preferred content of each element is, by mass, iron: 0.005% to 2.2%, magnesium: 0.05% to 1.0%, manganese, nickel, zirconium, zinc, chromium, and silver. : 0.005% or more and 0.2% or less in total; Copper: 0.05% or more and 0.5% or less; Silicon: 0.04% or more and 1.0% or less. These additive elements may be contained alone or in combination of two or more. In addition to the above additive elements, an alloy containing titanium and boron in a range of 500 ppm or less can be obtained. Examples of the alloy containing the additive element include aluminum-iron alloy, aluminum-iron-magnesium alloy, aluminum-iron-magnesium-silicon alloy, aluminum-iron-silicon alloy, aluminum-iron-magnesium- (manganese, nickel, Zirconium, silver) alloy, aluminum-iron-copper alloy, aluminum-iron-copper- (magnesium, silicon) alloy, aluminum-magnesium-silicon-copper alloy and the like.

  The aluminum alloy constituting the covered electric wire may be a single wire, a stranded wire formed by twisting a plurality of metal wires, or a compressed wire material obtained by compressing a stranded wire. The wire diameter of the core wire (in the case of a stranded wire, the wire diameter of the core wire before twisting) can be appropriately selected depending on the application. For example, a core material having a wire diameter of 0.1 mm to 1.5 mm can be used.

  The aluminum alloy constituting the covered electric wire (metal wire in the case of stranded wire) has a tensile strength of 110 MPa or more, a 0.2% proof stress of 40 MPa or more, an elongation of 10% or more, and a conductivity of 50% IACS (International Annealed Copper Standard) that satisfies at least one of the above. In particular, a core material having an elongation of 10% or more is excellent in impact resistance, and is difficult to be disconnected when a terminal fitting is attached to another terminal fitting, a connector, an electronic device, or the like.

  Examples of the insulating coating constituting the coated electric wire include various insulating materials such as polyvinyl chloride (PVC), a halogen-free resin composition based on a polyolefin resin, and a flame retardant composition. The thickness of the coating can be appropriately selected in consideration of desired insulation strength.

  The said core wire can be manufactured by the process of continuous casting rolling and wire drawing, for example. A covered electric wire can be manufactured by forming an insulating layer on the outer peripheral surface of the core wire.

  A plurality of terminal fittings 12 are connected to one edge side of the carrier C as shown in FIG. Each terminal fitting 12 is configured to protrude forward from the front edge of the carrier C. The terminal fittings 12 are arranged at predetermined intervals along the carrier C conveyance direction. Each terminal fitting 12 and the carrier C are connected by a connecting portion 13. That is, the terminal fitting 11 with a carrier is comprised by the some terminal metal fitting 12, the carrier C, and the several connection part 13 which connects between these.

  The main body portion 20 is formed by bending a bottom surface portion 22, a pair of side surface portions 23 rising from both side edges of the bottom surface portion 22, and bending from an upper edge of one side surface portion 23 toward an upper edge of the other side surface portion 23. And a ceiling portion 24.

  An elastic contact piece 21 that can be elastically displaced is formed inside the main body 20. The elastic contact piece 21 is formed by folding back from the front edge of the bottom surface portion 22. A mating conductor (not shown) in the form of a tab can be inserted between the opposing surface (the lower surface of the ceiling portion 24) facing the elastic contact piece 21 and the elastic contact piece 21 inside the main body 20. ing. The distance between the elastic contact piece 21 in the natural state and the opposing surface is set to be smaller than the plate thickness of the counterpart conductor. For this reason, when the counterpart conductor is inserted between the opposing surfaces while bending the elastic contact piece 21, the counterpart conductor and the elastic contact piece 21 are elastically contacted and electrically connected.

  The crimping portion 30 includes a wire barrel portion 31 having a substantially U shape and an insulation barrel portion 32 having a substantially U shape disposed behind the wire barrel portion 31. The crimping portion 30 has a bottom wall 33 that extends in the front-rear direction continuously to the bottom surface portion 22 of the main body portion 20.

  The wire barrel part 31 has a pair of caulking pieces 31 </ b> A and 31 </ b> A that rise in an opposed state from both side edges of the bottom wall 33. The wire barrel portion 31 can crimp the core wire 42 by placing the end of the core wire 42 on the bottom wall 33 along the front-rear direction and caulking the end of the core wire 42 with both the caulking pieces 31A and 31A. The core wire 42 is electrically connected to the both caulking pieces 31 </ b> A and 31 </ b> A and the bottom wall 33, so that the core wire 42 and the wire barrel portion 31 are electrically connected.

  The insulation barrel portion 32 has a pair of caulking pieces 32 </ b> A and 32 </ b> B rising from both side edges of the bottom wall 33. Both the caulking pieces 32A and 32B are arranged so as to be shifted in the front-rear direction. In the following description, the caulking piece located on the front side is 32A, and the caulking piece located on the rear side is 32B. The insulation barrel portion 32 is capable of crimping the coating 43 together with the core wire 42 by placing the coating 43 on the bottom wall 33 and caulking the coating 43 with both the caulking pieces 32A and 32B.

  As shown in FIG. 1, a transport hole 14 for transporting the carrier C is formed at a position corresponding to each connecting portion 13 in the carrier C. Each conveyance hole 14 is a circular hole and penetrates the carrier C in the plate thickness direction. The crimping machine 50 (see FIGS. 3 and 4) is provided with a conveyance shaft (not shown) that conveys the terminal fitting 11 with the carrier through the conveyance hole 14.

  As shown in FIG. 3, the crimping machine 50 includes an anvil 51 and a pair of crimpers 52 </ b> A and 52 </ b> B provided above the anvil 51. The wire barrel portion 31 and the insulation barrel portion 32 are placed on the anvil 51. Of the two crimpers 52A and 52B, the one corresponding to the wire barrel portion 31 is the first crimper 52A, and the one corresponding to the insulation barrel portion 32 is the second crimper 52B. Both crimpers 52A and 52B can be moved up and down by driving means (not shown).

  A cutting die (not shown) for cutting the terminal fitting 12 from the carrier C is provided on the rear side of the terminal fitting 12. After the terminal fitting 11 with the carrier is transported into the crimping machine 50 by the carrier C and the terminal of the covered electric wire 40 is arranged on the crimping part 30, the crimping part 30 is crimped by the crimping machine 50 and the crimping part 30 is cut. Separated from carrier C by mold. Thereby, the electric wire 10 with a terminal metal fitting is formed.

  By the way, an insulating oxide coating (for example, aluminum oxide) L is easily formed on the surface of the metal wire 41 constituting the core wire 42 by reacting with water or oxygen in the air. And when both 42 and 31 are connected with the oxide film L interposed between the core wire 42 and the wire barrel part 31, there exists a problem that electrical connection resistance becomes large.

  In this embodiment, the serration 34 is provided on the pressure contact surface in contact with the core wire 42 to solve this problem, so that the core wire 42 bites into the serration 34 and the oxide film L is broken at the edge portion of the serration 34. . The serrations 34 are formed in a groove shape extending in the width direction orthogonal to the front-rear direction in the wire barrel portion 31, and are arranged at three positions with a predetermined interval in the front-rear direction.

  However, in order to obtain a stable electrical connection resistance even in a durability test such as a thermal shock test, the compressibility of the wire barrel portion 31 (the conductor cross-sectional area after crimping is divided by the conductor cross-sectional area before crimping). It is necessary to lower the ratio calculated by doing this. Here, “lowering the compression rate” means compressing under higher compression pressure bonding conditions, and hereinafter simply referred to as “high compression”. Similarly, “increasing the compression rate” means compressing under a lower compression (gradual) pressure-bonding condition, and hereinafter simply referred to as “low compression”. When the wire barrel portion 31 is highly compressed, the wire barrel portion 31 is plastically deformed, and accordingly, the wire barrel portion 31 extends in the front-rear direction. In particular, when the rear end 13R of the joint portion 13 projects rearward from the rear end of the rear caulking piece 32B, the electric wire 10 with terminal fittings is inserted into a cavity (not shown) of a connector (not shown). When inserted, there is a problem that the rear end 13R of the connecting portion 13 protrudes rearward from the cavity, and the adjacent electric wires 10 with terminal fittings are likely to leak.

In this embodiment, as shown in FIG. 6, an alumite layer 35 is formed on the crimp surface (conductor contact surface in contact with the core wire 42) of the wire barrel portion 31 in this embodiment. The alumite layer 35 remains between the core wire 42 and the wire barrel portion 31 after the terminal fitting 12 is attached to the end of the covered electric wire 40. Since aluminum oxide (Al ₂ O ₃ ), which is the main component of the alumite layer 35, is an insulator, if the alumite layer 35 is too thick, there is a risk of increasing the electrical connection resistance. On the other hand, even if the alumite layer 35 is too thin, the oxide film L formed on the surface of the core wire 42 is not sufficiently destroyed, and there is a risk of increasing the electrical connection resistance. Therefore, the thickness of the alumite layer 35 is preferably 0.5 μm or more and 10 μm or less. The alumite layer 35 is a porous layer and has a finer crystal structure than the oxide film L. The hardness of the alumite layer 35 is 200 to 250 Hv. On the other hand, the hardness of the aluminum alloy as the base material is 30 to 105 Hv. That is, the alumite layer 35 is a hard layer that is harder than the base material. This is because when the wire barrel portion 31 is caulked, the anodized layer 35 cannot follow the wire barrel portion 31 and is broken into a plurality of anodized pieces, and these anodized pieces protrude from the surface of the wire barrel portion 31. It means that.

  The alumite layer 35 is formed by electrolytic treatment (specifically, treatment performed in the order of a degreasing step, an etching step, a water washing step, a pickling step, a water washing step, an anodizing step, and a water washing step). The degreasing step is a step of impregnating a commercially available degreasing solution, then impregnating the ethanol solution with stirring, and then performing ultrasonic cleaning. In the etching process, a sodium hydroxide aqueous solution (200 g / L, pH = 12) is used, and in the pickling process, a mixed acid aqueous solution in which nitric acid: 400 ml / L and 50% hydrofluoric acid: 40 ml / L are mixed is used. ing. In the anodic oxidation step, a dilute sulfuric acid solution (sulfuric acid aqueous solution (200 ml / L)) is used, and an alumite layer 35 having a desired thickness is obtained by adjusting the energization current and the energization time. Ultrasonic cleaning is used in the water washing step after etching, and running water is used in the water washing step after acid washing and the water washing step after anodization.

  In FIG. 6, in order to simply explain how the alumite layer 35 scrapes the oxide film L along with the pressure bonding, a metal strand 61 in which the oxide film L is formed on the surface of the core material 60 made of an aluminum alloy is shown. ing. First, when both the caulking pieces 31A and 31A are caulked from the state of FIG. 6 to deform the wire barrel portion 31, the anodized layer 35 cannot follow the deformation of the core member 60 and breaks. As shown in FIG. 7, the broken alumite layer 35 breaks the oxide film L so as to be peeled off, and the aluminum alloy which is the base material of the wire barrel portion 31 and the aluminum which is the core material 60 of the metal strand 61. The alloys are brought into an integrated state in pressure contact with each other so as to be conductive. Thereby, stable electrical connection resistance can be obtained even at low compression without making the wire barrel portion 31 highly compressed.

  The oxide film L that can be broken by the serration 34 is naturally limited to the oxide film L of the metal wire 41 disposed on the outer peripheral side of the core wire 42, and the inner metal that does not appear on the outer peripheral side of the core wire 42. Since the oxide film L of the strand 41 cannot be brought into direct contact with the serration 34, there is also a problem that a stable electrical connection resistance cannot be obtained.

  In this embodiment, this problem is addressed by using the core wire 42 in which the alumite layer 44 is formed on the surface of all the metal strands 41. The alumite layer 44 is formed by electrolytically treating the surface of an aluminum alloy that is a core material, similarly to the alumite layer 35 of the wire barrel portion 31, and other physical properties are the same as those of the alumite layer 35.

  Specifically, the manner in which the alumite layer 44 breaks the oxide film L as a result of pressure bonding will be briefly described with reference to FIGS. In FIG. 11 and FIG. 12, in order to simply explain how the alumite layer 44 breaks the oxide film L along with the pressure bonding, the metal element in which the oxide film L is formed on the surface of the base material 62 made of an aluminum alloy. A core wire 64 is illustrated in which a wire 63 and a metal strand 41 having an alumite layer 44 formed on the surface of a base material 62 made of an aluminum alloy are mixed and bundled. Moreover, although the alumite layer 44 is formed in the left half among the crimping | compression-bonding surfaces of the wire barrel part 31, the thing in which the alumite layer 44 is not formed in the right half is illustrated.

  First, as shown in FIG. 8, when the wire barrel portion 31 and the core wire 64 are placed on the anvil 51 and the first crimper 52A is lowered, as shown in FIG. It is bent inward by the first crimper 52A and bites into the core wire 64 from above. Further, when the first crimper 52A is lowered, as shown in FIG. 10, the wire barrel portion 31 is in a state of being crimped to the core wire 64 while the metal wires 41 and 63 are deformed.

  At this time, the anodized layer 44 cannot follow the deformation of each metal wire 41 and each caulking piece 31A, 31A and breaks. Then, as shown in FIG. 12, the broken alumite layer 44 breaks so as to scratch off the oxide film L on the surface of each metal strand 63, and the core of each metal strand 41 covered with the alumite layer 44. The material is exposed. Subsequently, the aluminum alloy that is the core material of the metal element wire 41 and the aluminum alloy that is the core material of the metal element wire 63 are brought into pressure contact with each other and are integrated so as to be conductive. In parallel with this, the base material of the wire barrel portion 31 covered with the anodized layer 44 is exposed, and the base material and the core material of each of the metal strands 41 and 63 are in pressure contact with each other and integrated. And are connected in a conductive manner. In this manner, the oxide film L that does not contact the serration 34 and the alumite layer 44 can be broken, and the metal wires 41 and 63 can be connected to each other even inside the core wire 64. Therefore, stable electrical connection resistance can be obtained even with low compression without making the wire barrel portion 31 highly compressed.

<Example>
Hereinafter, the present embodiment will be described in more detail with reference to examples. In the following description, the aluminum terminal corresponds to the electric wire 10 with terminal fittings of the embodiment, and the aluminum electric wire corresponds to the core wire 42 of the covered electric wire 40 of the embodiment.

  First, the surface state with and without alumite treatment will be described with reference to FIGS. In FIG. 13, after an aluminum terminal that has not been anodized is crimped to an aluminum wire that has not been anodized, the aluminum electric wire is peeled off from the aluminum terminal, and the crimped surface of the aluminum terminal is observed with an SEM image. It shows a state. Similarly, FIG. 15 shows a state where the surface to be bonded of the aluminum electric wire is observed with an SEM image. Looking at the left side of the enlarged view of FIG. 13, it can be seen that the crimp surface of the aluminum terminal is smooth. On the other hand, when the right side of the enlarged view of FIG. 15 is seen, it turns out that the to-be-crimped surface of an aluminum electric wire is also smooth.

  Next, FIG. 14 shows an aluminum terminal that has been alumite-treated and crimped to an aluminum wire that has not been alumite-treated, and then peeled off from the aluminum terminal, and the crimped surface of the aluminum terminal is shown by an SEM image. It shows how it was observed. Similarly, FIG. 16 shows a state where the surface to be bonded of the aluminum electric wire is observed with an SEM image. When the left side of the enlarged view of FIG. 14 is viewed, a plurality of scale-shaped anodized pieces that are broken by breaking the alumite layer are formed on the crimp surface of the aluminum terminal, and fine irregularities are formed on the entire crimp surface. I understand that. Similarly, when the enlarged view of FIG. 16 is seen, it turns out that the fine unevenness | corrugation is transcribe | transferred to the to-be-bonded surface of an aluminum electric wire.

  As can be seen from the SEM image, each anodized piece of aluminum scale breaks the oxide film of the aluminum wire, so that not only the serration edge but also the entire crimping surface of the aluminum terminal. This makes it possible to break the oxide film. However, as a premise that the oxide film can be broken by this method, the alumite needs to be broken into the scale-shaped alumite pieces, and before crimping the crimping surface of the aluminum terminal to the crimping surface of the aluminum wire, It is necessary to deform the crimping surface of the aluminum electric wire in order to break the anodized aluminum.

  Next, changes in the pressure-bonding portion resistance in the durability test (thermal shock test) will be described with reference to FIGS. 17 and 18. The base material of the aluminum terminal used in this durability test was a T6 treatment (3 hours heating at 550 ° C. for 3 hours) of an aluminum alloy plate made of JIS standard (JIS H 4000: 1999) 6000 series alloy (equivalent to 6061 alloy), followed by water cooling. And a process of heating at 175 ° C. for 16 hours). The average thickness of the anodized layer used in this durability test is 2 μm. The average thickness was measured by observing an SEM image of the cross section of the wire barrel portion. FIG. 17 shows changes in the crimped portion resistance of an aluminum wire with an aluminum terminal obtained by crimping an aluminum terminal that has not been anodized to an aluminum wire that has not been anodized. On the other hand, FIG. 18 shows a change in the crimping portion resistance of an aluminum electric wire with an aluminum terminal obtained by crimping an aluminum terminal subjected to anodizing to an aluminum electric wire not subjected to anodizing. In addition, crimping | compression-bonding part resistance is synonymous with the electrical-connection resistance of embodiment.

Table 1 shown below is the original data of the graph of FIG. 17, and Table 2 is the original data of the graph of FIG. The compression rate in FIGS. 17 and 18 is a ratio calculated by dividing the cross-sectional area of the core wire before crimping by the cross-sectional area of the core wire after crimping. That is, it means that the wire barrel portion is caulked with higher compression as the compression rate is smaller, and the wire barrel portion is caulked with lower compression as the compression rate is larger.

  First, as shown in FIG. 18, it can be seen that those subjected to the alumite treatment generally have a lower pressure-bonding portion resistance than those not subjected to the alumite treatment. Moreover, it can be seen that those subjected to the alumite treatment have a low pressure contact resistance regardless of the compression ratio. According to FIG. 18, since the resistance of the crimped part is stable at about 0.2 mΩ before and after the durability test in the compression rate range of 40 to 65%, and the increase in the crimped part resistance is hardly seen, the stable crimped part It can be seen that resistance is obtained. On the other hand, as shown in FIG. 17, in the case where the alumite treatment is not performed, it can be seen that the resistance of the crimping portion increases by about 0.2 mΩ at the maximum after the durability test in the range of the compression rate of 40 to 65%. It can be seen that in the case where the alumite treatment is performed in this manner, the resistance of the crimped portion hardly changes before and after the durability test, and the low resistance state is maintained. In particular, since the increase in the pressure-bonding portion resistance was not observed when the compression rate at which the pressure-bonding conditions were the most gentle was 65%, this meant that a stable pressure-bonding portion resistance could be obtained even under a mild pressure-bonding condition. Therefore, in the case where the alumite treatment is performed, a low resistance state can be maintained for a long time.

Next, changes in the pressure-bonded portion resistance due to the durability test (thermal shock test) when the boehmite treatment is performed on the wire barrel portion instead of the alumite treatment will be described with reference to FIGS. 19 and 21. FIG. Table 3 shown below is the original data of the graph of FIG. 19, Table 4 is the original data of the graph of FIG. 20, and Table 5 is the original data of the graph of FIG. The compression rate in FIGS. 19 to 21 is synonymous with the compression rate in FIGS. 17 and 18, and is a ratio calculated by dividing the cross-sectional area of the core wire before crimping by the cross-sectional area of the core wire after crimping. is there. That is, it means that the wire barrel portion 31 is crimped with higher compression as the compression rate is smaller, and the wire barrel portion 31 is crimped with lower compression as the compression rate is larger.

  Sample No. The aluminum terminals 200, 210, and 220 are samples obtained by performing boehmite treatment on the crimping surface of the wire barrel portion. In the boehmite treatment, the thickness of the boehmite layer was varied by changing the immersion time using a known method. The immersion time is the same as the sample No. 200 is the shortest. 210 is sample No. Longer than 200, sample no. 220 is sample No. It was made longer than 210. After the boehmite treatment, the average thickness of the boehmite layer was measured. 220 is 0.7 μm. 200 was 0.1 μm. The average thickness was measured by observing a cross-sectional SEM image in the same manner as the above-described anodized layer.

  As a core wire of an aluminum electric wire, a stranded wire formed by twisting together a plurality of metal strands (mass%, containing 1.05% iron and 0.15% magnesium, and the balance being aluminum) 11 strands having a wire diameter of 0.3 mm) were prepared, and each sample No. The wire barrel was crimped to the core by placing the core on the wire barrels 200, 210, and 220 and caulking. Each sample No. For each of 200, 210, and 220, five types of samples were prepared so that the compression rate was different by 5% within a range of 40 to 60%.

  Each sample No. For 200, 210, and 220, the initial pressure bonding resistance (before the durability test) and the pressure bonding resistance after the durability test were measured. The crimping part resistance was measured by the four-terminal method for aluminum terminals and aluminum wires. The results are shown in FIGS. FIG. The change of the crimping | compression-bonding part resistance of the aluminum wire with an aluminum terminal which crimped | bonded the aluminum terminal of 200 to the aluminum wire which has not been anodized is shown. 20 shows a sample No. The change of the crimping | compression-bonding part resistance of the aluminum electric wire with an aluminum terminal which crimped | bonded the aluminum terminal of 210 to the aluminum electric wire which has not been anodized is shown. FIG. 21 shows a change in the crimped portion resistance of an aluminum wire with an aluminum terminal in which the aluminum terminal of Sample No. 220 is crimped to an aluminum wire that has not been anodized.

  Sample No. subjected to boehmite treatment Among samples 200, 210 and 220, the sample No. with the thinnest boehmite layer was used. 200 is a pressure-bonded portion resistance comparable to that of the untreated sample (see FIG. 17), but the sample No. 200 has a boehmite layer thicker than this. It can be seen that 210 and 220 have a higher crimped portion resistance than the untreated sample. Sample No. 220 shows that the pressure-bonding portion resistance is different between the initial stage and the endurance, and the pressure-bonding portion resistance is increased after the endurance. That is, when the boehmite treatment is performed, it can be said that the pressure-bonding portion resistance tends to increase with time. From this, it can be seen that in the case where the boehmite treatment is performed, the boehmite layer is not destroyed at all, and the boehmite layer as an insulator is interposed between the wire barrel portion of the aluminum terminal. This is based on the fact that the boehmite layer has a dense layer of 30% of the total thickness and a porous layer of 70%, and the oxide film L cannot be destroyed because of the porous layer. On the other hand, since the alumite layer is almost entirely composed of a dense layer, it is easily broken, and the oxide film L is easily broken by the broken alumite pieces.

  As described above, in the present embodiment, since the surface of the metal element wire 41 is anodized to form the anodized layer 44, the anodized layer 44 is broken at the time of pressure bonding. The oxide film L on the surface of 41 can be broken. And since the aluminum alloy which is the core material of each metal strand 41 can be connected in a state where it is integrated, the metal strands 41 are connected even on the inner side that does not appear on the outer peripheral surface of the core wire 42. can do. Moreover, since the alumite layer 44 is formed in all the metal strands 41, the metal strands 41 can be reliably connected. Moreover, since the core material of the metal strand 41 is formed of an aluminum alloy, the alumite layer 44 can be formed simply by subjecting the core material to electrolytic treatment as it is.

  In addition, since the alumite layer 35 is formed by performing alumite treatment on the crimping surface of the crimping portion 30, the alumite layer 35 is broken during the crimping, and the oxide film L on the surface of the metal element wire 41 is broken by the broken alumite layer 35. Can break. And it can connect so that conduction | electrical_connection is possible in the state which integrated the aluminum alloy which is a core material of the metal strand 41, and the aluminum alloy which is a base material of the crimping | compression-bonding part 30. FIG. Moreover, since the base material of the crimping | compression-bonding part 30 was formed with the aluminum alloy, the alumite layer 35 can be formed only by electrolytically processing to a base material as it is.

<Other embodiments>
The present invention is not limited to the embodiments described with reference to the above description and drawings. For example, the following embodiments are also included in the technical scope of the present invention.
(1) Although the aluminum alloy is used as the core material of the metal strand in the above embodiment, aluminum may be used as the core material according to the present invention. Alternatively, a copper alloy may be used as the core material, and an aluminum alloy layer may be formed on the surface layer of the copper alloy, and the aluminum alloy layer may be subjected to electrolytic treatment to form an alumite layer.

  (2) Although all the metal strands 41 are alumite-treated in the above embodiment, according to the present invention, for example, only a metal strand passing through the axis of the core wire may be alumite-treated.

  (3) In the above embodiment, although the surface of the aluminum alloy layer is subjected to alumite treatment as the hard layer, according to the present invention, aluminum nitride may be used as the hard layer, or the surface of the aluminum alloy layer may be treated with allodin. Etc. may be given.

  (4) Although the alumite treatment is performed on both the wire barrel portion 31 and the core wire 42 in the above embodiment, according to the present invention, only the core wire 42 may be alumite treated.

  (5) In the above embodiment, the metal element wires are connected to each other by crimping the crimping pieces with a crimping die. However, according to the present invention, the metal element is formed by press-fitting the core wire between the pair of press contact blades. The lines may be pressed together.

DESCRIPTION OF SYMBOLS 10 ... Electric wire with a terminal metal fitting 12 ... Terminal metal fitting (before crimping) 30 ... Crimp part 40 ... Covered electric wire 41 ... Metal wire (core material)
42 ... Core wire 44 ... Anodized layer (hard layer)
60 ... Core material 61 ... Metal strand 62 ... Base material 63 ... Metal strand 64 ... Core wire L ... Oxide coating

Claims (10)

An electric wire connected to the terminal fitting by crimping,
Provided with a core wire formed by bundling a plurality of strands in which an aluminum layer or an aluminum alloy layer is formed on the surface layer of the core material,
An electric wire in which an insulating hard layer harder than the core material is formed on the surface of the aluminum layer or the aluminum alloy layer in at least one of a pair of adjacent wires.   The electric wire according to claim 1, wherein the hard layer is formed by altering a surface of the aluminum layer or the aluminum alloy layer.   The electric wire according to claim 1 or 2, wherein the hard layer is formed on all the strands.   The electric wire according to any one of claims 1 to 3, wherein the core material is the same metal material as the aluminum layer or the aluminum alloy layer and is integrated.   The electric wire according to any one of claims 1 to 4, wherein the hard layer is an alumite layer. The electric wire according to any one of claims 1 to 5,
The electric wire with a terminal metal fitting provided with the terminal metal fitting which has a crimping | compression-bonding part crimped | bonded to the core wire of this electric wire. The crimp portion provided on the terminal fitting, a method for producing a wire with the terminal fitting to be connected to the electric wire having a core wire formed by bundling a plurality of strands,
An aluminum layer or an aluminum alloy layer is formed on the surface layer of the core of the strand, and at least one of the adjacent strands has a hard layer harder than the aluminum layer or the aluminum alloy layer. Formed to cover the surface of the layer,
When crimping to the core wire while deforming the crimping portion, the hard layer is broken, and the broken hard layer exposes the core material by scraping the surface layer of the core material. A method of manufacturing an electric wire with a terminal fitting for pressure welding.   The manufacturing method of the electric wire with a terminal metal fitting of Claim 7 in which the said hard layer is formed in all the said strands.   The said core material is a manufacturing method of the electric wire with a terminal metal fitting of Claim 7 or Claim 8 which is the same metal material as the said aluminum layer or an aluminum alloy layer, and makes them.   The method for manufacturing an electric wire with a terminal fitting according to any one of claims 7 to 9, wherein the hard layer is an alumite layer.

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