JPH06267595A - Crimp metal fitting for electric wire - Google Patents

Abstract

PURPOSE:To reduce contact resistance in a short time with low power and without inviting the decrease in fastening force by depressing the deterioration in an electrical wire or electrodes for resistance welding. CONSTITUTION:The central parts at contact surfaces with the core wire part of a crimp metal fitting 26 are provided with metal bands 22 comprising low-m. p. metal such as tin, etc. Thus, compared with conventional ones having no metal bands, incoming heating value required for decreasing contact resistance down to a predetermined value is dramatically reduced, and the deterioration in an electrical wire 23 or electrodes 31a, 31b for resistance welding due to heat is depressed and the contact resistance is reduced in a short time with low power without inviting the decrease in fastening force.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric wiring circuit for a moving body such as an automobile, a ship, an aircraft, etc., as well as an industrial machine or the like, that is, a so-called wire harness, when connecting electric wires to each other or electric wires to each other and connecting terminals. The present invention relates to an electric wire crimping fitting used.

[0002]

2. Description of the Related Art Conventionally, in a wire harness, joining between electric wires and between electric wires and connecting terminals is generally performed by mechanical crimping. For example, as shown in FIG. When joining the wires, the insulation coating resins 1a and 2 of the portions of the wires 1 and 2 that are joined to each other are used.
After a is stripped to expose the core portions 1b and 2b of the electric wires 1 and 2 (coating stripping step), each exposed by the crimp metal fitting 3 of a metal plate made of copper or copper alloy. The core portions 1b and 2b are collectively held in a hugging state and pressure-bonded to each other (pressure-bonding step) to obtain an electrical connection.

Further, as shown in FIG. 5, in joining the electric wire 4 and the connection terminal 5 to each other, the insulating coating resin 4a at the end of the electric wire 4 is stripped off to expose the core wire portion 4b ( (Coating stripping process step), the exposed core wire portion 4b is press-fitted as a hug shape by the crimp fitting 6 integrally formed with the connection terminal 5 made of copper or copper alloy (crimp bonding) Process), and electrical connection was obtained.

By the way, pressurization of such a crimp fitting is
Taking the crimp fitting 3 as an example, it is performed as shown in FIG.

That is, as shown in FIG.
The crimping metal fitting 3 used for the joining has a substantially U-shaped cross section, and one end of each of the plurality of metal fittings 3 is integrally connected to a long feed plate 7 at regular intervals. Is moved in one direction by a moving means (not shown), and the respective metal fittings 3 are sequentially conveyed to the position of the pressure device described later.

At this time, feed holes 8 are formed in the feed plate 7 at the same pitch as the intervals of the metal fittings 3, and the metal fittings 3 are detected based on the positions of the feed holes 8.

Further, each metal fitting 3 is adapted to be pressure-bonded as described later and, at the same time, separated from the feed plate 7.

Next, the pressurizing device will be described. As shown in FIG. 6, it comprises an anvil 11 and a crimper 12. The anvil 11 is fixed at a predetermined position, and its upper surface 13 is fixed.
Has a slightly concave curved surface, and the metal fitting 3 is placed on the upper surface 13 of the anvil 11, and the exposed core wire portions of the electric wires 1 and 2 are arranged inside the metal fitting 3.

The crimper 12 is arranged above the anvil 11 so as to be movable up and down, and a depression 14 for pressurization is formed on the lower surface. The metal fitting 3 deformed by the pressure of the crimper 12 is guided into the depression 14. A pair of concave curved surfaces 14a and a convex portion 14b located at the confluence of the both concave curved surfaces 14a and protruding toward the anvil 11 are formed.
The lower part of the is expanded outward so that the metal fitting 3 can be easily guided.

The crimper 12 is vertically moved by a hydraulic cylinder or the like (not shown).

When the metal fitting 3 is conveyed onto the anvil 11 by the movement of the feed plate 7, the cores of the electric wires 1 and 2 are arranged inside the metal fitting 3 and the crimper 12 moves downward to move the metal fitting 3 Is pressed and deformed by the anvil 11 and the crimper 12, and the metal fitting 3 is crimped to the core wires of the electric wires 1 and 2,
The metal fitting 3 is cut and separated from the feed plate 7.

A crimping metal fitting 6 for joining the electric wire 4 and the terminal 5 as shown in FIG. 5 is also pressure-bonded by a similar pressurizing device.

By the way, due to the recent development of electronic technology,
The number of electronic components such as sensors used in the mobile body and industrial equipment continues to increase, and since the sensors themselves have become more sophisticated, the number of electric circuits that transmit weak electric signals has increased,
The electrical resistance of the electrical connection, which has not been a problem in the past, has become a major obstacle.

Further, various electric / electronic devices are mounted on various moving bodies, and a power source (for example, a battery in an automobile) is used.
The current also increases, and the increase in contact resistance at the wire connection portion may cause energy loss and, in the worst case, damage to the electric circuit due to heat generation and fire.

Therefore, it has been considered that the above-mentioned conventional mechanical crimping portion (crimping metal fitting) is subjected to thermocompression bonding at the joint portion after mechanical crimping in order to reduce the contact resistance. It is performed as shown in FIG.

That is, taking the case where the electric wires 1 and 2 are joined as an example, as shown in FIG.
A lower electrode 15 and an upper electrode 16 having the same shape as the crimper 12 are provided, and the upper electrode 16 is moved up and down by a hydraulic cylinder or the like like the crimper 12, and the metal fitting 3 after crimping is attached to the lower electrode 15. After being placed on the upper electrode 16, the upper electrode 16 moves downward, and the metal fitting 3 is held in a state of being pressed by both electrodes 15 and 16, and the metal member 3 is connected to both electrodes 15 and 16 by the DC power source 17 for thermal pressure welding. An electric current is passed between the electrodes 15 and 16, and the joint portions of the electric wires 1 and 2 are thermocompressed by the heat generation of the electrodes 15 and 16 to reduce the contact resistance. In addition, the thermal pressure welding of the joint portion of the electric wire-connecting terminal as shown in FIG. 5 is similarly performed.

[0017]

However, as described above, the crimp metal fittings 3 and 8 are made of copper or a copper alloy, and the core wire of an electric wire is also made of copper, and the electric resistance of these is small. In the conventional crimping metal structure, heat is hardly generated at the time of energization, and only the thermocompression bonding mode in which the electrodes 15 and 16 are heated to a high temperature is required, and it takes a long time to reduce the contact resistance of the joint portion to a predetermined value. Heat input is required,
As a result, the core wires of the electric wires 1 and 2 are likely to be softened by heat, and the strength of the electric wire itself is deteriorated by annealing, so that the fixing force is lowered, and the electrodes 15 and 16 themselves are heated to a high temperature. There is a possibility that the life may be shortened due to oxidation of the surface or generation of cracks.

Therefore, the present invention has been made in order to solve the above problems, and suppresses the deterioration of the electric wire and the resistance welding electrode so that the contact resistance can be reduced in a short time with a small amount of electric power. The purpose is to do.

[0019]

A wire crimping metal fitting according to the present invention is a wire crimping metal fitting which is resistance-welded after being crimped to an exposed core wire portion by stripping resin of the electric wire. It is characterized in that a metal band made of a low melting point metal which is formed in a direction orthogonal to the core portion and is melted by resistance welding is provided on the contact surface side with.

Further, the metal strip may be formed substantially in the center of the contact surface.

[0021]

In the present invention, since the metal strip made of a low melting point metal is provided on the contact surface side of the crimping fitting with the core wire portion, the metal strip can be melted at a low temperature to obtain an electrical connection. , The amount of heat input required to reduce the contact resistance to a prescribed value is significantly reduced compared to the conventional one without a metal band, and deterioration of electric wires and resistance welding electrodes due to heat is suppressed, and the adhesion force The contact resistance can be reduced in a short time with a small amount of power without causing a decrease.

Further, by forming the metal band made of a low melting point metal in the substantially central portion of the contact surface of the crimping fitting with the core wire portion, the influence of heat affects only the portion of the core wire portion in contact with the metal band. Therefore, the range in which the electric wire itself is deteriorated can be suppressed to be smaller than that in the conventional case, and the decrease in the fixing force can be effectively prevented.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an explanatory view of a crimping process of an embodiment of a crimping metal fitting of the present invention, and FIGS.

As shown in FIG. 2, in the central portion of the metal plate 21 made of copper or copper alloy, which is the material of the crimp fitting, is formed a low melting point metal such as tin or solder, which is narrower than the metal plate 21. The metal strip 22 is formed in advance, and the metal plate 2
1 is molded into a predetermined length to form a crimp fitting.

At this time, the metal strip 22 has a thickness of 10 to 10
About 0 μm is suitable, and the formation method may be any of well-known wet and dry plating, as well as screen printing and bonding.

Then, as shown in FIG. 1, a crimping metal fitting 26 is formed so that the above-mentioned metal band 22 is orthogonally contacted with the core wire portion 25 exposed by stripping the insulating coating resin 24 of the electric wire 23.
After crimping, the resistance welding electrodes 31a and 31b are brought into contact with both sides of the crimping metal fitting 26, and both electrodes 3a and
A welding current is passed between 1a and 31b to melt the metal strip 22 and alloy the copper of the core wire portion 25 with the tin of the metal strip 22 to reduce the contact resistance.

Therefore, the metal band 22 having a low melting point is attached to the crimp fitting 2
6 is formed on the contact surface side with the core wire portion 25, the metal band 22 is melted by a small amount of heat generated by a small welding current as compared with a conventional one without a metal band. Since the time required to lower the resistance is short and the supply current may be small, the heat input required to obtain the same contact resistance can be greatly reduced compared to the past, and heat can be continuously applied for a long time. Electric wire 2 by
3, deterioration of the electrodes 31a and 31b can be suppressed,
The contact resistance can be reduced without lowering the adhesive strength.

For example, as shown in FIG. 3, crimp metal fittings made of brass with a composition ratio of 7: 3, in which a metal band made of tin having a thickness of 30 μm is formed (corresponding to this embodiment: ● in FIG. 3) and metal. When the relationship between the welding current and the contact resistance was measured for a conventional one without a band (marked with ◯ in FIG. 3), the welding current required to reduce the contact resistance to about 0.1 mΩ was found in this example. In the case of No. 1, it was about 1.5 kA, whereas in the case of the conventional product, it was about 2 kA, and it was revealed that the desired contact resistance can be obtained with a welding current smaller than the conventional one.

Further, since the metal strip 22 is formed at the center of the contact surface of the crimp fitting 26 with the core wire portion 25, the influence of heat affects only the portion of the core wire portion 25 which is in contact with the metal strip 22. As a result, the range in which the electric wire itself is deteriorated can be suppressed to be smaller than in the conventional case, and it is possible to effectively prevent the decrease in the fixing force.

In the above embodiment, the case where the metal band 22 is formed at the center of the contact surface with the core wire portion 25 of the crimp fitting 26 has been described, but it is needless to say that it may be formed on the entire contact surface. .

[0031]

As described above, according to the crimp fitting for electric wire of the present invention, since the metal strip made of the low melting point metal is provided on the contact surface side of the crimp fitting with the core wire portion, the conventional one without a metal strip is provided. Compared with, the amount of heat input required to reduce the contact resistance to a predetermined value can be significantly reduced, deterioration of the electric wire and resistance welding electrode can be suppressed, and the adhesion strength can be reduced. It is possible to reduce contact resistance in a short time with less electric power, and in moving objects such as automobiles and industrial machines, energy loss due to heat generation of the drive power supply circuit and signal characteristics of low-voltage low-current circuits such as sensors. It is possible to prevent deterioration of the.

Further, by forming the metal strip in the center of the contact surface, it is possible to limit the range of deterioration of the electric wire due to heat, so that it is possible to effectively prevent the reduction of the fixing force.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a step in the middle of one embodiment of the wire crimping fitting of the present invention.

FIG. 2 is an operation explanatory diagram of FIG.

FIG. 3 is an operation explanatory diagram of FIG. 1.

FIG. 4 is a perspective view of a conventional example.

FIG. 5 is a perspective view of another conventional example.

FIG. 6 is an operation explanatory view of a step during the crimping of FIG.

FIG. 7 is an operation explanatory view of another step during the crimping of FIG.

[Explanation of symbols]

 22 Metal Band 23 Electric Wire 24 Insulation Coating Resin 25 Core Wire Part 31a, 31b Electrode for Resistance Welding

Claims (2)

[Claims] 1. A crimp metal fitting for an electric wire, which is resistance-welded after being crimped to an exposed core wire portion by stripping resin of an electric wire, in a direction orthogonal to the core wire portion on a contact surface side with the core wire portion. A crimp metal fitting for an electric wire, comprising a metal band made of a low melting point metal that is formed and melts by resistance welding. 2. The crimp metal fitting for an electric wire according to claim 1, wherein the metal band is formed substantially at the center of the contact surface.