JPH03184210A - Cable conductor for automobile - Google Patents

Abstract

PURPOSE:To make a 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) 60-120kg 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 0.01-0.25% 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 by 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.

Electric wires for control circuits, 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 thicker than the electrically required diameter to ensure mechanical strength. This is because it increases 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
Conductors using materials such as phosphor bronze containing %Sn have also been developed and are used in some areas (Special Publications No. 60-30043, No. 6l-
29133).

[Problem that the invention seeks to solve]

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 conductor, which increases the amount of insulator used and the wiring space. In addition to increasing costs, sufficient weight reduction effects cannot be expected.

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. The limit is 0.15 to 0.3 mm, and if you lower it to the currently required 0.05 to 0.15 + os, the strength will still be insufficient, or even if it is strong, 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 t of 60
~120kg, conductivity is 25% IACS or higher, surface layer is copper or copper alloy, core metal part has carbon content of 0.01-0.25%
In addition, Si, Mn, P, S, Ni are added as additional elements.
Composite structure elementary conductors made of steel containing 5Cr etc. are twisted together and the total cross-sectional area of the conductor after twisting is 0.05 to 0.30a.
m", and the conductor breaking load T is 6 kg or more.

FIG. 1 shows a cross section of one example, and the illustrated electric wire conductor 1 is constructed by twisting seven element conductors 2 each having a diameter d. In the figure, 3 is a steel wire serving as the core of the bare conductor, and 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 metal core is coated with 20 to 80% by weight of oxygen-free copper or copper alloy.

The upper limit of the conductivity of the elementary conductor should also be kept at 80% [Function] If a composite with a copper (including alloy) coating is used as the elementary conductor, the required conductivity (25% IACS or more) and solder adhesion can be maintained. properties can be obtained by coating copper.

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 higher than before because steel wire containing 0.01 to 0.25% C is used as the core 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 t of the elementary conductor is 60~
60kg was limited to 120kg/llll112
/m" or less, the total cross-sectional area D=0.
This is because the conductor breaking load at 1 mm" is less than 6 kg, which may cause the wire to break or fail to provide a satisfactory terminal holding force. On the other hand, if t = 120 kg/1 IIlt or more, the characteristics of the m-wire used This is an unreasonable value.A more desirable value for tensile strength considering the holding force of the terminal is 80 to 110 kg.
/Open 2.

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 acceptable type i1A 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 set to 0.05 to 0°30.
The reason why we chose Kaku 2 is that when D = 0.30 am" or more, the required strength can be obtained with conventional products, but the purpose of weight reduction cannot be achieved. On the other hand, when D = 0.05 m" or less, T is 5.
This is because a structure with a diameter of 710.08 kg or less is likely to be deformed due to tension. A more desirable value of this D is 0.07
~0.20+nm".

Conventional annealed copper wire has a total cross-sectional area of D=0.3a due to its mechanical properties.
n2 is the limit, and copper containing Sn (0.3 to 0.9 Sn)
But 3J! The limit is usually D=0.2mII+2,
According to the present invention, even if D=0.1 mm2, the conventional 0.
The same strength as 3-layer 2 products can be obtained, and the weight of the electric wire can be reduced (for example, 0.1 mm" is 60% less than 0.3-layer 2).

In addition, the carbon content of the steel wire used as the core metal of the elementary conductor is 0. The reason for limiting O to 1 to 0.25% is that if it is less than 0.01%, it is difficult to secure a tensile strength t of 60 kg/m+m' or more, preferably 80 kg/am' or more, and if it is less than 0.25% This is because intermediate heat treatment becomes difficult, and unless special heat treatment is performed, a material with high strength, that is, a material with good bending value and difficult to break, cannot be obtained.Here,
In the steel, SiO,3 is added as a deoxidizer or to prevent embrittlement.
% or less, Mn 1.5% or less, other p, so, Ni, C
r is slightly lowered.

〔Example〕

Four types of 81111φ steel ronds with different carbon contents were prepared as core metal materials for elementary conductors of samples NαI to 4 shown in the table of FIG. The steel has S i (
0.1-0.3%) and Mn (0.6-1.3%). In addition, the target 11ilvi4 for sample Hiro 1 to 3
An oxygen-free tJ4 (JIS 3510) pipe (hereinafter referred to as an OFC pipe) was prepared as the pipe, and a 0.3% Sn-containing steel pipe was prepared as the sample hole 4. These coated steel pipes are all straight pipes with an outer diameter of 16mm and an inner diameter of 12aa.

Next, in order to obtain a composite conductor from these materials, the surface of each of the steel rondos is dry polished (shot plus polishing) and inserted into the OFC pipe and Sn-containing steel pipe, and then squeezed with a fitting die. It was made to have a diameter of about 10m. This results in
The electrical conductivity is about 40%, about 60%, about 3 in order from sample Nα1.
0%, resulting in a copper composite of approximately 25%.

Therefore, these materials were repeatedly drawn and softened to a length of 0.5 m.
I made it m. After final softening was performed at 600 to 800°C for about 1 hour, wire drawing was performed so that the diameter d became 0.127 wrφ. 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 wires and the total cross-sectional area D = 0.0
8~O,IIl+a+'' was made into an electric wire conductor, which was then coated with a 0.2 mm thick vinyl chloride coating 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 body 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, the tensile breaking load is preferably about 10 kg or more without losing the flexibility of the conductor, and the higher 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, and then examining the ratio of the area wetted by molten solder to the total immersed surface area. A score of less than 90% was graded as poor.

As can be seen from the data in the table, when comparing the weight reduction effect of T4vA between the inventive product and the conventional product, the total cross-sectional area D = 0
．． 3m” conductor (sample output, 6), wire weight is 5.0g/m
D=O, 1m” (sample Ncil~
4) becomes 1.4-1.5g/m, about 3.5g7m,
It was possible to reduce the weight by about 70%. The strength in this case is equivalent 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 reductions in vehicle weight and wiring space due to an increase in the number of wiring locations, as well as cost reductions 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 view explaining the mode of a bending test, and FIG. 3 is a table comparing the bending characteristics. 1...Wire conductor, 2...Elementary conductor,
3... Steel wire, 4... Oxygen-free copper, 5... Coated 1! Line, 6...Jig, W...Load. Figure 1 Figure 20

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<120, conductivity of bare conductor is 25%IACS or more, 0.05<D<0.3
0, T>6, and the above elementary conductor has a surface layer of copper or copper alloy, and a core metal part with a carbon content of 0.01 to 0.25.
An electric wire conductor for an automobile, characterized in that it is a composite element conductor made of steel containing Si, Mn, Ni, Cr, etc. as additive elements in the amount of %. (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.