JP2014187011A - Terminal, method of manufacturing the terminal, and termination connection structure of electric wire - Google Patents

Abstract

An object of the present invention is to provide a terminal having a tube-shaped crimping portion that is inexpensive, has good formability, and has high sealing reliability of a welded portion.
A terminal having a contact portion for connecting to another terminal and a tubular caulking portion for connecting to a covered electric wire, wherein the terminal is made of a solid solution type copper alloy, A terminal characterized in that the dislocation density in the weld of the base metal part and the tubular caulking part satisfies both of the following mathematical formulas (1) and (2).
(Dislocation density of the base material part of the contact part after heat treatment after welding / dislocation density of the base material part of the contact part after welding) ≧ 0.60 (1)
(Dislocation density of the weld after heat treatment after welding / dislocation density of the weld after welding) ≦ 0.60 (2)
[Selection] Figure 1

Description

  The present invention relates to a component responsible for electrical conduction. In more detail, it is related with the 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 base material and sealing it (for example, see Patent Document 3) is disclosed, but the process is similarly complicated and the sealing is performed. There was a problem that the reliability of the property was lacking.

  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 solve these problems, a method of strengthening a welded part such as performing an aging heat treatment on a welded pipe is known (for example, see Patent Documents 5 and 6).

JP 2011-222243 A JP 2004-207172 A JP 2012-84471 A JP 2007-203330 A JP 2012-84471 A JP-A-6-88177

  However, a terminal with a contact portion has a problem that when aging heat treatment is performed, deterioration of characteristics (strength and spring characteristics) due to softening of the material is inevitable, and terminal required characteristics such as contact resistance cannot be satisfied. Also, as described in Patent Document 6, the strips are finished in a solid solution state, and after joining and aging heat treatment, since the material strength of the solid solution is low, the press formability at the time of terminal manufacture is poor, and the aging heat treatment There is a problem that it is difficult to mold into a desired shape, such as dimensional variation later. Furthermore, aging heat treatment is a production method limited to precipitation type alloys.

  Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide a tube-shaped terminal that is inexpensive, has good formability, and has high sealing reliability of a welded portion.

A feature of the terminal of the present invention is a terminal having a contact portion for connecting to another terminal and a tubular caulking portion for connecting to a covered electric wire, and the terminal is made of a solid solution type copper alloy, The gist is that the dislocation density in the base metal part of the contact part and the welded part of the tubular caulking part satisfies both the following mathematical formulas (1) and (2).
(Dislocation density of the base material part of the contact part after heat treatment after welding / dislocation density of the base material part of the contact part after welding) ≧ 0.60 (1)
(Dislocation density of the weld after heat treatment after welding / dislocation density of the weld after welding) ≦ 0.60 (2)

  Here, the contact portion refers to a leaf spring portion including a contact portion that makes contact with another terminal, such as a female terminal. Further, the base material portion refers to a base material of the material of the region constituting the contact portion. If it is a male terminal, an insertion tab becomes a contact part.

  As the solid solution type copper alloy, any one of a Cu—Mg alloy, a Cu—Zn alloy, a Cu—Sn alloy, and the like can be selected.

  The welded portion of the terminal is preferably formed by fiber laser welding.

  The gist of the manufacturing method of the terminal according to the present invention is that, after forming the crimped portion by welding, at least the welded portion is subjected to a local heat treatment.

  The heat treatment is preferably performed on the entire terminal after forming the tubular crimped portion by welding.

  The gist of the terminal connection structure of the electric wire of the present invention is that the terminal of the present invention and the electric wire are crimped and connected at the tubular caulking portion of the terminal.

  According to the present invention, it is possible to provide a terminal having a tube-shaped crimping portion that is inexpensive, has good formability, and has high sealing reliability of a welded portion.

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. It is a perspective view which shows the other example of the tubular crimping part of the terminal which concerns on embodiment of this invention. It is a perspective view which shows the other example which changed the female terminal of the terminal which concerns on embodiment of this invention into the male terminal.

  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. Note that the same number is assigned to the same element throughout the description of the embodiment.

  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 part (first welded part) 50 and a welded part (second welded part) 51 in the tubular caulked part 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, for example, a part or all of the terminal 1 may be subjected to tin plating or silver plating. 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. The welding part 51 is welding for closing and sealing the end part of the tubular caulking part 30 on the transition part 40 side. Thereby, infiltration of moisture and the like from the transition portion side can be reduced.

(Box part, contact 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 box portion 20 of the terminal of the present invention is provided with a contact for electrical connection with insertion tabs and pins of other terminals. Since it is preferable that the terminal can be inserted and removed, the contact pressure of the contact is usually taken by the restoring force of the spring. The terminal of the present invention has a contact provided with a leaf spring mechanism by bending a tabular member extending in the longitudinal direction of an insertion tab or pin of another terminal. A portion for taking a contact with another terminal is referred to as a contact portion. In the case of a male terminal, the insertion tab itself is referred to as a contact portion.

(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 a wire insertion port 31 into which an aluminum or aluminum alloy 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 as a weld part 51. If moisture adheres to the contact between the 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, so that the caulking part will infiltrate moisture from the outside. It is tubular so that it does not. 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.

  In the tubular caulking portion 30, the copper alloy and the aluminum or aluminum alloy electric wire constituting the tubular caulking portion are mechanically pressure-bonded to each other, thereby ensuring electrical connection at the same time. The copper alloy base material and the electric wire (core wire) are plastically deformed and joined by caulking. Therefore, it is necessary to design the wall thickness of the tubular caulking portion 30 so that it can be caulked and joined, but since it can be freely joined by human processing or machining, it is not particularly limited. Absent.

  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 and an electric wire 60 (for example, a covered electric wire made of a core wire made of aluminum or an aluminum alloy) are connected. In the electric wire terminal connection structure 10, the terminal 1 and the electric wire 60 are crimped and connected by a tubular caulking portion 30. The manner of crimping is not particularly limited, but in FIG. 2, it is composed of a first crimped reduced diameter portion 35, a second crimped reduced diameter portion 36, and a third reduced diameter portion 37. 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 than the original diameter. In the example shown in FIG. 2, the concave portion 35 a of the first crimped reduced diameter portion 35 is a portion having the highest diameter reduction rate. The third reduced diameter portion 37 has a diameter smaller than the original diameter and is in close contact with the insulating coating of the electric wire. In addition, illustration of the welding part 50 and the welding part 51 was abbreviate | omitted in FIG.

In addition, the electric wire 60 consists of the insulation coating 61 and the core wire of the electric wire which is not shown in figure. 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. An existing metal material can be used for the core wire of the electric wire, and it is made of, for example, copper or a copper alloy, aluminum or an aluminum alloy. As described in the background art, in recent years, an aluminum or aluminum alloy core wire has been used for weight reduction. However, the electric wire 60 of the present application is not limited to aluminum or an aluminum alloy. This is because the waterproof property of the connecting portion between the core wire and the terminal of the electric wire can be cited as an issue regardless of the combination of any metal species. Using such a core wire, for example, a core wire in which 7 to 19 strands are twisted so as to have a cross-sectional area of 0.5 to 2.5 sq (mm ² ) can be used. As the core wire covering material, for example, a material mainly composed of polyolefin 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 part 30 so as to overlap the tubular caulking part 30 by the length, and the caulking process is carried out with a dedicated jig or a press machine.

(Terminal manufacturing method)
The terminal 1 of the present invention is formed by punching a strip made of a copper alloy base material into a terminal shape that is flattened, and providing a box portion and a caulking portion by bending. At this time, since the caulking portion has a C-shaped cross section when bent from a plane, the open portion is joined by welding. And in order to block | close the edge part by the side of the transition part 40 of the tubular crimping part 30, it will become the tubular crimping part 30 by overlapping and welding the base materials of a tubular body. 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 unwelded portion 38 (butting portion) over the tubular caulking portion 30. After welding, a weld 50 is formed. Moreover, in order to block | close the edge part by the side of the transition part 40 after this welding, the overlapping part of the base materials of a tubular body is welded. After this welding, a weld 51 as shown in FIG. 1 is formed. 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 this embodiment, after welding the tubular crimping portion 30 of the terminal 1 made of a solid solution type copper alloy base material in a work-hardened state using a fiber laser welding apparatus, further heat treatment is performed to remove welding distortion. doing. Welding strain removal can be performed by local heating of the welded portion by laser, heating of the entire terminal by a heat treatment furnace, or the like. The mechanical strength of the solid solution type copper alloy is directly related to the dislocation density. However, excessive heat treatment affects not only the welded portion but also the strength of the tubular crimped portion 30 itself.

If the heat treatment is to be performed only on the welded portion, for example, local heating with a laser is preferably performed. When the distortion of the welded portion is removed, the base material of the terminal made of a copper alloy is softened and the amount of plastic deformation is recovered, so that defects such as cracks are less likely to occur when crimping with an electric wire later. Further, not only local heat input to the welded portion but also the same effect can be obtained by applying heat treatment to the entire terminal. However, it is necessary to perform heat treatment so that the strength of the entire terminal (particularly the contact portion) does not decrease. That is, it is necessary to perform heat treatment so that the dislocation density of each part of the terminal satisfies the following formulas (1) and (2), whether local heat treatment or global heat treatment.
(Dislocation density of the base material part of the contact part after heat treatment after welding / dislocation density of the base material part of the contact part after welding) ≧ 0.60 (1)
(Dislocation density of the weld after heat treatment after welding / dislocation density of the weld after welding) ≦ 0.60 (2)

  A male / female fitting terminal with a male tab width of 2.3 mm is produced by press forming and forming a tubular crimped portion by fiber laser welding using a JIS C2600 EH material or a JIS C5200 H material with a plate thickness of 0.25 mm. did. Here, EH and H are classification symbols used in JIS. After heat-treating this terminal and measuring the dislocation density ratio of the base metal part of the contact part and the dislocation density ratio of the welded part, these dislocation degree ratios and the contact resistance after crimping the terminal and the aluminum alloy wire The relationship with anticorrosion sealability was evaluated.

<Copper alloy>
The following copper alloy was used as the base material for the terminals.
JIS C2600: Cu 68.5-71.5% by mass, Pb ≦ 0.05% by mass, Fe ≦ 0.05% by mass, balance Zn
JIS C5200: Pb ≦ 0.05 mass%, Fe ≦ 0.15 mass%, Sn 7.0-9.0 mass%, Zn ≦ 0.20 mass%, P 0.03-0.35 mass%, Cu + Sn + P99.7 % By mass

<Wire core wire>
An Fe-Cu-Mg-Si-based aluminum alloy (wire diameter 0.43 mm, 19 strands) was used for the core wire of the electric wire.

<Laser welding conditions>
Laser welding equipment: ASF1J23 (Furukawa Electric Co., Ltd., trade name), 500 W, CW fiber laser Sweep irradiation using a galvano scanner (non-telecentric) Laser beam output: 400 W
Sweep distance: 9mm (butting part about 7mm)
Laser focal diameter 20μm
Sweep speed 140mm / s
Laser beam irradiation with all conditions just focus

<Laser local heating conditions>
Laser welding equipment: ASF1J23 (Furukawa Electric Co., Ltd., trade name), 500 W, CW fiber laser Sweep irradiation using a galvano scanner (non-telecentric) Laser beam output: 400 W
Sweep distance: 9mm (butting part about 7mm)
Laser focal diameter 20μm
Sweep speed 800mm / s
Laser beam irradiation with all conditions just focus

<Measurement of dislocation density>
By direct observation using a TEM (transmission electron microscope), several fields were observed at a magnification of 10,000 to 1,000,000 times, and the dislocation density per unit area was calculated.

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

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

Example 1
JIS C2600 (EH material) was used as a substrate, and after the butt welding with a fiber laser, the welded portion was locally heated with a laser.

(Example 2)
JIS C2600 (EH material) was used as a base material, and heat treatment at 200 ° C. for 2 hours was performed in the air after butt welding with a fiber laser.

(Example 3)
JIS C5200 (H material) was used as a base material, and after the butt welding with a fiber laser, the welded portion was locally heated with a laser.

Example 4
JIS C5200 (H material) was used as a base material, and heat treatment was performed at 200 ° C. for 2 hours in the air after butt welding with a fiber laser.

(Comparative Example 1)
JIS C2600 (EH material) was used as a base material, and butt welding was performed using a fiber laser. No heat treatment after welding.

(Comparative Example 2)
JIS C2600 (EH material) was used as a substrate, and heat treatment was performed at 450 ° C. for 30 minutes in the air after butt welding with a fiber laser.

(Comparative Example 3)
JIS C5200 (H material) was used as a base material, and butt welding was performed using a fiber laser. No heat treatment after welding.

(Comparative Example 4)
JIS C5200 (H material) was used as a base material, and heat treatment was performed at 450 ° C. for 30 minutes in the air after butt welding with a fiber laser.

* Dislocation density of base metal part of contact after heat treatment after welding / Dislocation density of base metal part of contact after welding
** Dislocation density of weld after heat treatment after welding / Dislocation density of weld after welding

  Table 1 shows the evaluation results. As can be seen from Examples 1 to 4, solid solution type copper alloys JISC2600 (EH material) and JIS C5200 (H material) as base materials, after butt welding with a fiber laser, the local heating of the welded portion with laser or shown in the table All the terminals produced by heat treatment under the above conditions showed good contact resistance and anticorrosion sealability, although the dislocation density in the welded portion was reduced. On the other hand, in Comparative Examples 1 and 3 in which solid solution type copper alloys JIS C2600 (EH material) and JIS C5200 (H material) are used as base materials without being subjected to heat treatment after butt welding by a fiber laser, The dislocation density did not change in both the base metal part and the welded part, indicating a low anticorrosive sealability. In addition, Comparative Example 2 in which a solid solution type copper alloy JIS C2600 (EH material) and JIS C5200 (H material) were used as base materials and a terminal was prepared by performing high temperature heat treatment of 450 ° C. × 30 min after butt welding with a fiber laser. In No. 4, since the dislocation density of the base material portion of the contact portion decreased, a high contact resistance was exhibited.

As mentioned above, although the terminal of this invention was demonstrated based on drawing, the aspect of the terminal of this invention is not limited to this.
The tubular caulking portion 30 shown in FIG. 1 is formed from a plurality of tubes having different inner diameters, such as a stepped caulking portion 130, in a state before being crimped to an electric wire, such as the terminal 100 shown in FIG. It may be configured. Specifically, the stepped tubular caulking portion 130 is a member whose transition portion 40 side is closed by a welded portion 51, a cover crimping portion 133 to be crimped to an insulating coating 61 of an electric wire 60 (not shown), and an insertion port 31. From the side to the transition portion 40 side, the diameter-reduced portion 134, the core wire crimping portion (conductor crimping portion) 135 to be crimped to the core wire (conductor) of the electric wire 60, and the insertion port 31 side to the transition portion 40 side. Further, the diameter may be further reduced, and the end may have a reduced diameter portion 136 that is closed by welding. In FIG. 4, there are two types of tubular portions (covered crimping portion 133, core wire crimping portion (conductor crimping portion) 135), but three or more types may be used according to the application and design.

  Thus, when the stepped tubular caulking portion 130 has a stepped shape, when the insulating coating 61 at the end of the electric wire 60 is removed and the end is inserted into the stepped tubular caulking portion 130, the insulating coating 61 of the electric wire 60 is The insulation coating 61 is positioned immediately below the cover crimping portion 133, and the core wire (conductor) of the electric wire 60 is positioned directly below the core wire crimping portion (conductor crimping portion) 135. Therefore, the end portion of the electric wire 60 can be easily positioned, and the crimping between the covering crimping portion 133 and the insulating coating 61 and the crimping between the core wire crimping portion (conductor crimping portion) 135 and the core wire (conductor) are reliably performed. It is possible to achieve both excellent water tightness and electrical connection and to achieve excellent adhesion.

  Moreover, although the example of the female terminal which has the box part 20 is shown in the terminal 1 of FIG. 1, not only this but the connection part with another terminal may be a male terminal. Specifically, as shown in FIG. 5, an insertion port 31 into which an unillustrated electric wire 60 is inserted, a tubular caulking portion 30 to be crimped to the electric wire 60, the tubular caulking portion 30, and the transition portion 40. It may be a terminal 200 provided with a male connection part 220 that is provided integrally and electrically connected to an external terminal (not shown). The male connection part 220 has a long insertion tab 220a, and the insertion tab 220a is an external terminal (not shown) female terminal (for example, a terminal having a box part 20 as shown in FIG. 1). It is electrically connected by being inserted in 1) along the longitudinal direction. Further, a terminal having a male connecting portion 220 at the front end and a stepped caulking portion 130 as shown in FIG. 4 at the rear end is also allowed. In the case of a male terminal, the insertion tab 220a corresponds to the contact portion.

  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. 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.

1 Terminal 10 Terminal Connection Structure 20 Female Terminal Box 30 Tubular Caulking 31 Wire Insertion Port 32 Contact (Spring Contact)
35 1st crimping reduced diameter part 36 2nd crimping reduced diameter part 37 3rd crimping reduced diameter part 38 Unwelded part 40 Transition part 50 Welded part (1st welded part)
51 Welded part (second welded part)
60 Electric Wire 61 Insulation Cover 100 Terminal 130 Stepped Caulking Part 133 Cover Crimp Part 134 Reduced Diameter Part 135 Core Wire Crimp Part (Conductor Crimp Part)
136 Reduced diameter part 200 Terminal 220 Male connection part 220a Contact part (insertion tab)
FL Fiber laser welding equipment L Laser beam

Claims (6)

A terminal having a contact portion for connecting to another terminal and a tubular caulking portion for connecting to a covered electric wire,
The terminal is made of a solid solution type copper alloy,
A terminal in which a dislocation density in a base metal part of the contact part and a welded part of the tubular caulking part satisfies both of the following mathematical formulas (1) and (2).
(Dislocation density of the base material part of the contact part after heat treatment after welding / dislocation density of the base material part of the contact part after welding) ≧ 0.60 (1)
(Dislocation density of the weld after heat treatment after welding / dislocation density of the weld after welding) ≦ 0.60 (2)   The 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, a Cu—Sn alloy, and the like.   The terminal according to claim 1, wherein the weld is formed by fiber laser welding. It is a manufacturing method of the terminal given in any 1 paragraph of Claims 1-3,
A method of manufacturing a terminal, comprising: forming a tubular caulking portion by welding and then subjecting at least the weld portion to a local heat treatment. It is a manufacturing method of the terminal given in any 1 paragraph of Claims 1-3,
A method for manufacturing a terminal, comprising: forming a tubular caulking portion by welding and then performing heat treatment on the entire terminal.   The terminal connection structure of the electric wire which crimp-connected the terminal of any one of Claim 1 to 3, and the electric wire in the tubular crimping part of the said terminal.