JPH03184211A - Automotive wire conductor - Google Patents

Abstract

PURPOSE:To make cable conductor lightweighted by satisfying specified conditions of tensile strength of elemental conductor before twisting, total cross section surface area after twisting, and breaking load of the conductor and preparing the cable conductor as a composite conductor consisting of a copper or copper alloy surface layer and a core part of a steel containing specified additional elements. CONSTITUTION:Composite elemental conductors 2 having tensile strength (t) 60-140kg and conductivity at least 25% IACS and composed of a copper or copper alloy surface layer 4 and a core part 3 of a steel containing 0.25-0.85% C and Si, Mn, P, S, Ni, Cr, etc., as other additional elements are twisted each other. Consequently, breaking load T of the conductor 1 caused tensile force and holding force in terminal housings and bending strength of an electric cable are improved as compared with a conventional one and thus the cross section surface area of a conductor can be decreased after the elemental conductors are twisted so as to make the cable lightweighted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a lightweight electric wire conductor for automobiles.

[Conventional technology]

JISC31 is mainly used as a wire conductor for wiring in automobiles.
Annealed copper wire as specified in 02 or wires plated with tin are used, and this is coated with an insulator such as vinyl chloride, cross-linked vinyl, or cross-linked polyethylene, and used as an electric wire. there was.

However, as the performance of automobiles increases, the number of various control circuits increases, resulting in an increase in the number of wiring locations within the automobile.Therefore, there is an increasing demand for weight reduction while maintaining reliability. Electric wire conductors tend to be avoided.

Control circuit wires, which account for most of the wiring, carry signal currents, so most of them have an allowable current of less than IA, but conventional wire conductors have a diameter that is smaller than the electrically required diameter to ensure mechanical strength. This is because a thicker one has no choice but to increase the weight of the vehicle.

Therefore, in an attempt to reduce the weight of this type of electric wire, some studies have been made to use aluminum (including alloys, hereinafter referred to as "aluminum") for the conductor. In addition, 0.3-0.9% Sn copper alloy wire and 4-8
%Sn Conductors using large Lirin bronze bars have also been developed and are used in some areas (Special Publications No. 60-30043, No. 6l-
29133).

[Problems to be solved by the invention] Aluminum is weak in strength, and in order to obtain sufficient wire strength, it is essential to take measures such as increasing the outer diameter or increasing the number of twisted wires in the elementary conductor. This increases the amount of body used and the wiring space, leading to an increase in cost, and it is not possible to expect sufficient weight reduction effects.

In addition, many terminals are used in automobile wiring, but these terminals have various problems such as electrical corrosion and poor solderability.

On the other hand, in the wire conductor shown in the above-mentioned publication, the strength of the copper wire is increased by adding Sn, which makes it possible to reduce the cross-sectional area of the wire after twisting, but the cross-sectional MD of the wire conductor is The limit is 0.15~0.3+m'', and if you lower it to the currently required 0.05~0.15m'', the strength will still be insufficient, or even if it has strength, the conductivity will be less than 20% IACS. Therefore, the problem of increased electrical resistance remained.

An object of the present invention is to solve these problems and provide an electric wire conductor for an automobile that is further lightweight while ensuring reliability.

[Means to solve the problem]

The automotive wire conductor proposed by the present invention has a tensile strength of 60
~140kg! Electricity is 25%lAc5 or more, surface layer is copper or copper alloy, core metal has carbon content 0°25-0.85%
, other additive elements include Si, Mn, P, S, Ni,
Composite structure elementary conductors made of steel containing Cr etc. are twisted together and the total cross-sectional area of the conductor after twisting is 0.05 to 0.3011I.
112, the conductor breaking load T is 6 kg or more.

Figure 1 shows the cross section of one example, and the illustrated electric wire conductor 1 is constructed by twisting seven elementary conductors 2 with a diameter d. 3 in the figure is the core metal of the elementary conductor w4I ! ! , 4 is oxygen-free copper coated on the outer periphery of 3.

In order to maintain the flexibility of the electric wire conductor, it is better to have more twists in the elementary conductor 2 even if the cross-sectional area is the same.
In this case, it is necessary to prepare thin bare conductors and set a large number of bare conductors in the wire twisting machine during twisting, which is difficult, so 2 to 37 conductors, more preferably 7 to 19 is recommended.

Further, the elementary conductor used is preferably one in which the outer periphery of the core metal is coated with 20 to 80% by weight of oxygen-free steel or copper alloy.

The upper limit of the conductivity of the elementary conductor is also preferably 80%.

[Function] When a composite body having a copper (including alloy) coating is used as an elementary conductor, the necessary electrical conductivity (25% IACS or more) and solder adhesion can be obtained by the copper coating.

In addition, the breaking load T due to tension of the conductor, the holding force in the terminal housing, and the wire bending value are different from those of conventional ones because steel wire containing 0.25 to 0.85% C is used as the core metal 7 of the elementary conductor. Therefore, it is possible to reduce the weight by reducing the cross-sectional area of the conductor after twisting.

Here, in this invention, the tensile strength of the elementary conductor is 60~
The limit to 140 kg/m1 is 60 kg/mta.
``Below, in the case of 7-stranded electric wire, the total cross-sectional area D = 0.1
This is because the breaking load of the conductor at t = 140 kg/open 2 or more is less than 6 kg, which may cause the wire to break or fail to obtain a satisfactory terminal holding force. This is an unreasonable value due to its nature.It is more desirable that the tensile strength t is 80 to 130 kg/m considering the holding force of the terminal.
n''.

Furthermore, the reason why the conductivity of the elementary conductor is set to 25% IACS or more is based on the result of calculating the allowable current from the electrical resistance value of the conductor when the surface layer of the elementary conductor is formed of oxygen-free copper or copper alloy. If the allowable current IA is the minimum condition, the conductivity is 25% or more,
If possible, an IACS of 30 to 40% or more is optimal. Note that the upper limit of the electrical conductivity is 80% IACS when trying to maintain the necessary tensile strength using a composite, and if it exceeds this, the tensile strength will be sacrificed.

Next, the total cross-sectional area of the conductor after twisting is 0.05 to 0.30.
The reason for setting uz is that if D = 0.30 mm" or more, conventional products can obtain the required strength, but the purpose of weight reduction cannot be achieved. On the other hand, if D = 0.05 am" or less, T is 5 kg or less, 710 This is because the .08φ structure is likely to be deformed due to tension. A more desirable value of this D is 0.0
7 to 0.20 m”.

Conventional annealed copper wire has a total cross-sectional area of D=0.5+ due to its mechanical properties.
nm” is the limit, and Sn-containing R (0.3 to 0.93n
), the limit is usually D = 0.2 mm, but according to the present invention, even with D = 0.b + o", the same strength as the conventional 0.3 tone 2 products can be obtained, and the weight of the electric wire can be reduced ( For example 0.1m
60% reduction of 0.3+nm").

In addition, the carbon content of the steel wire used as the core metal of the elementary conductor is limited to 0.25 to 0.85%, which is 0.2! If it is less than 0.25%C, it is difficult to secure a tensile strength of 100 kg/IIN" or more, preferably 120 kg/mm2 or more.If it is more than 0.25%C, it will be difficult to maintain a tensile strength of 100 kg/IIN" or more, preferably 120 kg/mm2 or more. It is difficult to obtain a material that has a good bending value and is difficult to break, so it is difficult to obtain a material that has a good bending value and is hard to break.
When using a steel wire with a temperature of 40% C or higher, the temperature is raised to exceed the transformation point (723°C), and then a batenting treatment is performed to transform it into a bainite structure at around 400°C. Element wire is a strong material that is very easy to work with. The reason why the upper limit of the C content was set at 0.85% is that if the C content was higher than this, the steel wire would be extremely hard and it would be very difficult to thin the wire even after patenting treatment.

〔Example〕

Four types of 8uΦΦ steel ronds with different carbon contents were prepared as core metal materials for elementary conductors in samples Nos. 1 to 4 shown in the table of FIG. In addition, an oxygen-free copper (LrS 3510) pipe (hereinafter referred to as an OFC pipe) was prepared as a coated steel pipe for sample Nal~3, and a steel pipe containing 0.3% Sn was prepared as a coated steel pipe for sample No.4. These coated steel pipes are all straight pipes with an outer diameter of 16-φ and an inner diameter of 125 wφ.

Next, in order to obtain a composite conductor from these materials, the surface of each of the above-mentioned steel rondos is dry-polished (dry polishing).
While doing so, it was inserted into the OFC pipe and the Sn-containing steel pipe, and this was squeezed with a fitting die to a diameter of approximately 10 mm. As a result, the 24-electroconductivity is approximately 30%, approximately 45%, and approximately 45% starting from sample Nαl.
It became a copper composite of about 60% and about 25%.

Therefore, these materials were repeatedly drawn and softened to 0.5+
+m+φ. A special patenting process was performed for final softening. Then, this wire was drawn so that the diameter d was 0.12711 Imφ. The tensile strength and electrical conductivity of the elementary conductor thus obtained are as shown in the table of FIG.

After this, each elementary conductor is twisted into 7 wood wires and the total cross-sectional area D = 0.0
8 to 0.1M" wire conductor, and furthermore, 0.1M" wire conductor.
A 2++++l+ thick vinyl chloride coating was applied to make an electric wire for an automobile.

The characteristics of these electric wires are shown in the table of FIG. 3 along with the characteristics of conventional products and comparative products.

The terminal housing retention force is an important characteristic for the reliability of the connection to the terminal in automotive electric wires, and this characteristic is determined by crimping the conductor to the terminal and then pulling the conductor in the axial direction using a tensile tester. The load at which the wire was pulled out (or broken) was measured. It is desired that this holding force be 7 kg or more in most cases, preferably 10 kg or more.

Further, it is desirable that the tensile breaking load is approximately 10 kg or more without losing the flexibility of the conductor, and the larger the better.

Regarding the bending resistance of the electric wire, it is desirable that the conductor does not break when repeatedly bent, especially near the terminal portion, and this measurement is performed by placing the coated electric wire 5 in a jig 6 shown in FIG. 90° to the left and right with a load W of 500g applied to one end.
It was bent alternately at 90 degrees, and the number of times it took to break was expressed as one round trip of 90 degrees.

Solderability was determined by immersing the specimen in white rosin flux and then immersing it in eutectic solder at 230°C for 2 seconds.
The ratio of the area wetted by the molten solder to the total immersed surface area was examined, and those of 90% or more were considered good, and those less than 90% were judged bad.

As can be seen from the data in the table, when comparing the weight reduction effect of the electric wire between the inventive product and the conventional product, the total cross-sectional area D = 0.3
m" conductor (sample N116) and the wire weight was 5.0 g/m, but D = 0.1 mm" (sample N11l ~
4) becomes 1.4 to 1.5 g/m, which is approximately 3.5 g/m
, it was possible to reduce the weight by about 70%. The strength in this case is comparable to that of conventional products.

〔effect〕

As described above, according to the present invention, the holding force of the terminal housing, tensile breaking load, mechanical properties such as bending resistance, electrical properties, and solderability can be fully satisfied, and the large width of the wire conductor can be improved. This has the effect of contributing to suppressing increases in vehicle weight and wiring space due to an increase in the number of wiring locations, and reducing costs by reducing the amount of insulators used.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of the present invention, FIG. 2 is a diagram explaining type B of the bending test, and FIG. 3 is a table comparing the bending characteristics. 1...Wire conductor, 2...Elementary conductor,
3...Steel wire, 4...Oxygen-free steel, 5...Coated electric wire, 6...Bin fixture, W... ·load.

Claims (3)

[Claims] (1) The tensile strength of the bare conductor before twisting is t (kg/mm^2)
, when the total cross-sectional area of the conductor after stranding is D (mm^2) and the conductor breaking load is T (kg), 60<t<140, conductivity of bare conductor is 25%IACS or more, 0.05<D<0.3
0, T>6, and the element conductor has a surface layer of copper or copper alloy, and a core metal having a carbon content of 0.25 to 0.85.
An electric wire conductor for an automobile, characterized in that it is a composite element conductor made of steel containing Si, Mn, P, S, Ni, Cr, etc. as additive elements in %. (2) The electric wire conductor for an automobile according to claim 1, wherein the elementary conductor is a metal core (steel) whose outer periphery is coated with 20 to 80% by weight of oxygen-free copper or copper alloy. (3) The electric wire conductor for an automobile according to claim (1) or (2), wherein the elementary conductor has an upper limit of electrical conductivity of 80% IACS.