JP2014164911A - Copper alloy terminal and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tubular shaped a copper alloy terminal that is inexpensive and good in formability and has high sealing reliability of a welded portion, and a method for manufacturing the copper alloy terminal.SOLUTION: A copper alloy terminal 1 is a terminal including a tubular caulking part 30 formed of a base material of a solid solution type copper alloy. The caulking part includes a welded portion 50 joined by the welding of a part 37 to be welded. A plating layer is provided in the part to be welded before welding. The welded portion has a precipitation phase comprising an element constituting the plating layer in a base martial of the solid solution type copper alloy.

Description

  The present invention relates to a component responsible for electrical conduction. In more detail, it is related with the copper alloy terminal which connects an electric wire.

  2. Description of the Related Art Conventionally, in a wire connecting portion in an assembled wire for automobiles, a form in which a wire conductor is crimped with a terminal is common. Usually, copper wires are used as the assembled wires, but aluminum wires (hereinafter also referred to as aluminum wires) may be used for the purpose of weight reduction. In general, the crimping portion has a structure in which the electric wire conductor is exposed. Therefore, when an aluminum electric wire is used, there is a possibility that the aluminum of the conductor is corroded and electrical conduction cannot be secured.

  In order to prevent this, it is conceivable to shield the aluminum conductor from the environment. For example, it is desirable to cover the aluminum surface so as not to touch air. From the standpoint of preventing corrosion, a method of molding the entire crimped part with resin (for example, see Patent Document 1) is reliable, but the molded part becomes enlarged and the size of the connector housing needs to be increased. As a result, the entire assembled electric wire could not be formed into a high-density compact size. In addition, since the molding process is performed on each crimped part after crimping, there are problems such as greatly increasing the number of steps for manufacturing the assembled wire and complicated operations.

  On the other hand, a technique for blocking the aluminum conductor from the outside by a method of crimping after covering the electric wire conductor with the metal can was proposed (for example, see Patent Document 2), but the can is attached to each conductor before the crimping. There are problems such as a complicated process and a case where the can is broken by a wire barrel and a water immersion path is formed at the time of pressure bonding. Moreover, although the terminal and the cap are not separate parts, a technique for covering the electric wire with a part of the terminal strip and sealing it (for example, refer to Patent Document 3) is disclosed, but the process is similarly complicated and the sealing property is closed. There was a problem of lack of reliability.

  The problem as described above can be solved by adopting a structure in which an electric wire is inserted into a tubular terminal and crimped, thereby blocking the wire conductor from the outside without enlarging the crimped portion. There are several methods for forming the tube. From the viewpoint of processing speed and cost, it is preferable to use a laser welding method (for example, see Patent Document 4).

  However, since the welded part is a solidified structure and residual strain exists in the welded part, the welded pipe is inferior in crimping strength and durability reliability as compared with the pipe without joining, and it is sealed during use as a terminal. There is a risk that it may not be possible to maintain. In order to strengthen the structure, a technique is known in which the plated portion is diffused into the base material and alloyed to positively improve the material properties (for example, see Patent Documents 5 to 7).

JP 2011-222243 A JP 2004-207172 A JP 2012-84471 A JP 2007-203330 A JP 2004-188522 A Japanese Patent No. 2554235 Japanese Patent Laid-Open No. 5-1367

  However, the methods disclosed in Patent Documents 5 to 7 are methods for strengthening the structure in the vicinity of the surface of the base material by diffusion in the vicinity of the interface between the plating and the base material. The effect is small because it is not done.

  Accordingly, the present invention has been made in view of the above problems, and an object thereof is to provide a tube-shaped copper alloy terminal that is inexpensive, has good formability, and has high sealing reliability of a welded portion, and a method for manufacturing the same. And

  A feature of the copper alloy terminal of the present invention is a terminal having a tubular caulking portion made of a solid solution type copper alloy base material, and the tubular caulking portion is welded by joining the welded portions. The welded part is provided with a plating layer before welding, and the welded part has a precipitation phase composed of elements constituting the plating layer in the base material of the solid solution type copper alloy. And

  The laser welding part is irradiated with a laser beam and heated locally, or the copper alloy terminal including the laser welding part is subjected to low-temperature heat treatment, so that the elements constituting the plating layer are precipitated in the base material of the laser welding part. The laser welded portion can be strengthened without reducing the strength of the base material excluding the laser welded portion.

  The solid solution type copper alloy is made of any one of a Cu—Mg alloy, a Cu—Zn alloy, and a Cu—Sn alloy.

  The element constituting the plating layer is one or a plurality selected from Sn, Ni, Si and Cr. Si may be an oxide or the like dispersed in the plating metal. This is because it can be melted by laser welding.

  According to the present invention, it is possible to provide a pipe-shaped copper alloy terminal that is inexpensive, has good formability, and has high sealing reliability of a welded portion, and a method for manufacturing the same.

It is a perspective view which shows the terminal which concerns on embodiment of this invention. It is a perspective view which shows the connection structure of the terminal which concerns on embodiment of this invention, and the terminal of an electric wire. It is a perspective view which shows typically an example of the welding method of the terminal which concerns on embodiment of this invention.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention (hereinafter referred to as embodiments) will be described in detail with reference to the accompanying drawings.

  FIG. 1 shows a terminal 1 according to an embodiment of the present invention. The terminal 1 has a female terminal box portion 20 and a tubular caulking portion 30, and has a transition portion 40 as a bridge between them. Further, the terminal 1 has a welded portion 50 (portion indicated by hatching in the drawing) continuous to the tubular caulking portion 30. The terminal 1 is manufactured with a copper alloy base material in order to ensure conductivity and strength. However, in order to ensure various characteristics of the terminal 1, a part or all of the surface of the terminal 1 may be plated. Further, the shape of the welded portion is not particularly limited. Although it is good to form in the strip | belt shape in the longitudinal direction of the tubular crimping part 30 like the welding part 50 shown in figure, you may form in a wavy line shape or a helical shape.

(Box part)
The box part 20 of the female terminal is a box part that allows insertion of an insertion tab such as a male terminal. The detailed shape of the box portion is not particularly limited. That is, it is not necessary to have a box part, for example, it may be an insertion tab of a male terminal. Moreover, the edge part of another terminal may be sufficient. In the present embodiment, an example of a female terminal is shown for the sake of convenience in order to describe the terminal of the present invention, and any terminal having a connecting end portion is tubular through the transition portion 40. A caulking portion 30 is provided, and the tubular caulking portion 30 is formed by welding.

(Tubular caulking part)
The tubular caulking part 30 is a part that crimps and joins the terminal 1 and an aluminum or aluminum alloy electric wire (not shown). One end thereof has an electric wire insertion port 31 into which an aluminum electric wire can be inserted, and the other end is connected to the transition portion 40. It is preferable that the transition part 40 side of the tubular caulking part 30 is closed. If water adheres to the contact between the copper or copper alloy of terminal 1 and aluminum or aluminum alloy wire, either metal (alloy) will corrode due to the difference in electromotive force between the two metals. It is tubular so that it does not enter. If the crimping portion of the terminal is tubular, a certain effect against corrosion can be obtained. Therefore, the crimping portion is not necessarily cylindrical with respect to the longitudinal direction, and may be an elliptical or rectangular tube depending on circumstances. Moreover, the diameter does not need to be constant, and the radius may change in the longitudinal direction.

  Although not shown in the drawings, the tubular caulking portion 30 may be provided with a locking groove (serration) such as a groove or a protrusion in order to make an electrical connection with the electric wire or make it difficult to pull out the electric wire.

(Wire end connection structure)
Next, FIG. 2 shows an end connection structure 10 for electric wires according to the present invention. The terminal connection structure 10 has a structure in which the terminal 1 of the present invention is connected to an aluminum electric wire or an aluminum alloy electric wire (electric wire 60). In the terminal connection structure 10, the terminal 1 and the electric wire 60 are crimped and joined by the tubular caulking portion 30. Although the manner of crimping is not particularly limited, in FIG. 2, it is composed of a first crimping reduced diameter portion 35 and a second crimping reduced diameter portion 36. Normally, when crimped and joined, the tubular caulking portion 30 undergoes plastic deformation and is crimped to the electric wire 60 by being reduced in diameter from the original diameter. In the example shown in FIG. 2, the first crimped reduced diameter portion 35 is a portion where the diameter reduction rate is the highest. In this way, the crimp bonding may be performed with two stages of diameter reduction.

  The electric wire 60 includes an insulating coating 61 and a core wire of aluminum or an aluminum alloy (not shown). Although the electric wire 60 may be a bare wire, from the viewpoint of corrosion prevention, an electric wire with an insulation coating is usually used.

As the core wire of the aluminum electric wire, for example, iron (Fe) is about 0.2% by mass, copper (Cu) is about 0.2% by mass, magnesium (Mg) is about 0.1% by mass, silicon (Si) About 0.04 mass%, and the balance can be aluminum (Al) and an aluminum core wire consisting of inevitable impurities. As other alloy compositions, Fe is about 1.05 mass%, Mg is about 0.15 mass%, Si is about 0.04 mass%, the balance is Al and inevitable impurities, or Fe is about 1.0 % By mass, about 0.04% by mass of Si, the balance being Al and inevitable impurities, about 0.2% by mass of Fe, about 0.7% by mass of Mg, about 0.7% by mass of Si, and the balance Al and inevitable impurities can be used. These may further contain alloy elements such as Ti, Zr, Sn, and Mn. Using such an aluminum core wire, for example, a core wire of 0.5 to 2.5 sq (mm ² ) and 7 to 19 strands can be used. As the core wire covering material, for example, a material mainly composed of polyelephine such as PE or PP, a material mainly composed of PVC, or the like can be used.

  In the present embodiment, the electric wire 60 obtained by removing the insulating coating 61 at the tip portion by a predetermined length using the electric wire 60 coated with the insulating coating is used. It is inserted into the tubular caulking portion 30 so as to overlap the tubular caulking portion 30 by the length, and the caulking process is carried out with a dedicated jig or a press machine.

  In the present embodiment, in order to ensure the mechanical strength of the tubular caulking portion, as a base material of the terminal 1, a Cu—Mg alloy, a Cu—Fe alloy, a Cu—Zn alloy, a Cu—Sn alloy, etc. A base material (plate material) made of a solid solution type copper alloy is used.

(Terminal manufacturing method)
The terminal 1 of the present invention is punched into a terminal shape in which a strip material made of a solid solution type copper alloy base material is flattened, and a box portion and a caulking portion are provided by bending. The surface plating layer may be provided on the strip in advance, or may be plated after punching. Since the portion to be the tubular caulking portion has a C-shaped cross section when bent from a plane, the tubular caulking portion 30 is formed by joining the open portions by welding. In the present embodiment, the tubular caulking portion 30 is formed by fiber laser welding.

  Copper and copper alloys have low laser absorptivity and high thermal conductivity, so the welding width may not be reduced or the width of the heat affected zone may not be reduced. Improved. The laser beam by the fiber laser has the characteristics that the condensing diameter is small, the energy density is high, the condensing distance is long, and the output can be increased by connecting modules in parallel. Furthermore, by using a lens or a mirror, there is an advantage that even if the distance between the fiber laser main body device and the object to be processed (the part to be welded) is long, it can be transmitted directly to the object to be processed by the fiber.

  FIG. 3 is a diagram schematically illustrating an example of a welding method for the terminal 1 according to the present embodiment. FL in the figure represents a fiber laser welding apparatus. The laser beam L emitted from the fiber laser welding apparatus FL is irradiated so as to weld the welded portion 37 (butting portion) over the tubular caulking portion 30. Although FIG. 3 shows an example in which a laser beam is irradiated from one fiber laser welding apparatus, a plurality of fiber laser welding apparatuses may be connected in parallel to irradiate a plurality of laser beams. In this case, each beam may have the same output or a combination of different outputs.

  In the present embodiment, after welding the tubular caulking portion 30 of the terminal 1 made of the above solid solution type copper alloy base material, which has a plated layer on the surface and is in a work-hardened state, using a fiber laser welding apparatus, welding is performed. The portion 50 is irradiated with a laser beam and locally heated, or the terminal 1 including the welded portion 50 is subjected to low-temperature heat treatment to form precipitates made of elements constituting the plating layer in the base material of the welded portion 50. . In addition, this plating layer should just be provided in the site | part (to-be-welded part) to which laser welding is performed at least.

  The plating layer may be formed only on one side of the substrate or on both sides. The plating layer can be composed of one or more elements selected from Sn, Ni, Si and Cr. If the plating thickness (in the case of double-sided plating, the total plating thickness of each side) is within the range shown in Table 1 for the base plate thickness, the heat treatment after welding will strengthen the weld 50. An effective precipitated phase (precipitate, compound) is formed.

  Cu-Mg based alloys, Cu-Fe based alloys, Cu-Zn based alloys, Cu-Sn based alloys, etc. are solid solution type copper alloys, but are deposited in the substrate by incorporating the elements of the plating layer described above. There will be a phase. In other words, the structure of the welded portion after laser welding is basically composed of a Cu matrix phase and a precipitated phase precipitated by taking in the plating element, and the alloy element originally dissolved in the Cu matrix phase is dissolved in the Cu matrix phase. It will be in the state.

When the welded portion is brought into such a structural state by laser welding and heat treatment (aging treatment), the mechanical strength of the tubular crimped portion and the welded portion is kept high. Moreover, since the laser weldability is also improved by the plating layer applied on the copper substrate, the productivity is also excellent.

(Examples 1-3) and (Comparative Examples 1-3)
A male and female with a male tab width of 2.3 mm by press forming and forming a tubular caulking portion by fiber laser welding using a 0.25 mm thick plate of H material of EFTEC-3 (Furukawa Electric Co., Ltd. trade name) A fitting terminal was produced. This terminal was subjected to heat treatment, and the phase state of the welded portion was analyzed, the hardness of the base material excluding the welded portion and the welded portion, the anticorrosion seal test, and the contact resistance measurement were performed. For the heat treatment, only the welded portion was irradiated with a laser beam to locally heat it, or the entire terminal was subjected to a low-temperature heat treatment at 250 ° C. for 30 minutes in a heating furnace. For comparison, in Comparative Example 3, high-temperature heat treatment at 450 ° C. × 30 min was performed.

<Plating and dispersion plating conditions>
(Ni plating)
Treatment liquid:
_{Ni (SO 3 NH 2) 2} · 4H 2 O: 500g / l,
NiCl ₂ : 30 g / liter,
H ₃ BO ₃ : 30 g / liter Current density: 15 A / dm ²
Temperature: 50 ° C

(Ni plating with Si dispersed)
For Si, it was difficult to plate directly, so silica was dispersed in another plating metal. In this example, the Ni plating layer was dispersed.
Treatment liquid:
_{(SO 3 NH 2) 2 ·} 4H 2 O: 500g / l NiCl _2: 30 g / l _H 3 _BO 3: 30g / l MP-2040 (manufactured by Nissan Chemical Industries, Ltd., average particle size 200 nm): 40 g / l , Dodecylamine: 0.3 g / l
Current density: 15 A / dm ²
Temperature: 50 ° C

(Cr plating)
Treatment liquid:
Chromic acid: 200 g / liter Sulfuric acid: 2 g / liter Current density: 50 A / dm ²
Temperature: 50 ° C

(Sn plating)
Treatment liquid: 524M (trade name) liquid manufactured by Ishihara Pharmaceutical Co., Ltd. Treatment temperature: 30 ° C
Current density: 5 A / dm ²

(Ag plating)
Treatment liquid:
AgCN: 50 g / liter KCN: 100 g / liter K ₂ CO ₃ : 30 g / liter Current density: 3 A / dm ²
Temperature: 30 ° C

  In addition, the plating thickness of each metal seed | species was changed by changing time. Samples having a predetermined plating thickness were prepared, and samples were selected so that the desired plating thickness was within ± 0.2 μm.

<Copper alloy base material composition, mass%>
EFTEC-3: Sn0.1, Cu residue The remaining Cu may contain inevitable impurities.

<Aluminum alloy core wire composition, mass%>
Core wire of aluminum electric wire: Fe0.2, Cu0.2, Mg0.1, Si0.04, balance is Al and inevitable impurities (wire diameter 0.43mm, 19 strands)

<Laser welding conditions>
Laser welding equipment: ASF1J23 (Furukawa Electric Co., Ltd., trade name), 500 W, CW fiber laser Laser beam output: 400 W
Sweep distance: 9mm (butting part about 7mm)
Sweep speed 140mm / s
Laser beam irradiation with all conditions just focus

<Local heating conditions>
The local heating conditions were set to 800 mm / s instead of 140 mm / s during the welding conditions, and the other conditions were the same.

<Analysis of phase state of weld zone>
The weld was analyzed with EDX attached to the SEM, and XRD pattern identification was performed as necessary.

<Hardness measurement>
After embedding the resin, the cross section was obtained by polishing, and the Vickers hardness (Hv) was measured at n3 in accordance with JIS Z 2244.

<Evaluation of anti-corrosion seal properties>
After fitting and caulking the aluminum alloy electric wire, positive pressure of 10 to 50 kPa was applied from the electric wire insertion side to check the presence or absence of air leakage, and evaluation was performed according to the following criteria.
No air leakage: ○
With air leakage: ×

<Evaluation of contact resistance>
The contact resistance after fitting and caulking an aluminum alloy electric wire was measured and evaluated according to the following criteria.
<3mΩ: ○
≧ 3 mΩ: ×

  Table 2 shows the evaluation results. As can be seen from Table 2, in Examples 1 to 3 where the welded portion was locally laser-heated or the whole terminal was subjected to low-temperature heat treatment at 250 ° C. for 30 minutes, Hv of the welded portion was 100 to 120, compared with the plating Compared to the Hv of the welded part of Example 1, it was as high as the Hv of the base material excluding the welded part, and both the anticorrosion sealability and the contact resistance were good. In Comparative Example 2, it was not alloyed because the order of the multilayer plating was inappropriate. In Comparative Example 3 in which high-temperature heat treatment at 450 ° C. for 30 minutes was performed, Hv of the base material excluding the welded portion was reduced.

  As mentioned above, although this invention was demonstrated using embodiment, it cannot be overemphasized that the technical scope of this invention is not limited to the range as described in the said embodiment. In particular, although the present invention has been described with respect to female terminals, it is naturally applicable to male terminals. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above-described embodiments. Further, it is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Terminal 10 Termination connection structure 20 Female terminal box part 30 Tubular crimp part 31 Electric wire insertion port 35 1st crimping | compression-reducing diameter part 36 2nd crimping | compression-reducing diameter part 37 Welded part (butting part)
40 Transition part 50 Welding part 60 Electric wire 61 Insulation coating FL Fiber laser welding equipment L Laser beam

Claims (3)

A terminal having a tubular caulking portion made of a solid solution type copper alloy base material,
The tubular caulking portion has a welded portion joined by welding the welded portion,
The welded part is provided with a plating layer before welding,
The copper alloy terminal, wherein the welded portion has a precipitated phase composed of an element constituting the plating layer in a base material of the solid solution type copper alloy.   The copper alloy terminal according to claim 1, wherein the solid solution type copper alloy is made of any one of a Cu—Mg alloy, a Cu—Zn alloy, and a Cu—Sn alloy.   3. The copper alloy terminal according to claim 1, wherein the element constituting the plating layer is one or more selected from Sn, Ni, Si, and Cr. 4.

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