JPH03184212A - 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 specified composite elemental conductor. CONSTITUTION:Composite elemental conductors 2 having tensile strength (t) 60-140kg and conductivity at least 25% IACS and composited of a copper or copper alloy surface layer 4 and a core part 3 of an Fe-based alloy containing Ni, Cr, etc., 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 due to using the Fe-based alloy as the core of the element conductor, and thus the cross section surface area 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 a strand of tin-plated cotton is 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 is unavoidable to use it, and it causes an increase in weight.

Therefore, in an attempt to reduce the weight of this type of electric wire, some studies have considered using aluminum (including alloys, the same hereinafter) for the conductor. In addition, conductors using 0.3 to 0.9% 5nIJJ4 alloy wire and phosphor bronze containing 4 to 8% Sn have been developed and used in some cases (Japanese Patent Publications No. 60-30043, No. 61-29133). .

[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. , the amount of insulator used and the wiring space increase, leading to an increase in cost, and a sufficient weight reduction effect 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 tpaaz, and the currently required 0.05 to 0.15 al+++
If the strength was lowered to 20%, the strength would still be insufficient, and even if strength was present, the electrical conductivity would be less than 20% IACS, resulting in a high electrical resistance.

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 for Solving the Problems] The automotive wire conductor proposed by the present invention has a tensile strength t of 60
~140 kg, conductivity of 25% IACS or higher, surface layer made of copper or copper alloy, core metal part made of Fe-based alloy containing Nj, Cr, Si, Mn, etc. Composite structure element conductor is twisted together. The total cross-sectional area of the conductor is 0.05 to 0.30 m”,
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 an Fe-based alloy wire that becomes the core metal of the elementary 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.

Metal elements other than Fe used in the metal core include Co, Mo, Nb, etc. in addition to those mentioned above.

It is preferable that the core metal contains 20 to 80% by weight of one or more selected from these elements including the above-mentioned elements, with the balance being iron.

Further, the elementary conductor used is preferably one in which the outer periphery of the core metal is coated with 25 to 80% by weight of oxygen-free copper or copper alloy.

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

[Effect]

When a composite with a copper (including alloy) coating is used as the elementary conductor, the necessary electrical conductivity (25% IACS or higher) and solder adhesion can be obtained by the copper coating.

In addition, the breaking load T due to conductor tension, the holding force in the terminal housing, and the wire bending value are higher than before because Fe-based alloy wire is used as the core of the bare conductor, and therefore, the Weight reduction can be achieved by reducing the cross-sectional area of the conductor.

Here, in this invention, the tensile strength of the elementary conductor is 60~
140 kg/+s+e” is limited to 60 kg/
11111” or less, total cross-sectional area D for 6-stranded wire
= 0.1+mm" conductor breaking load is less than 6 kg, which may cause the wire to break or fail to provide a satisfactory terminal holding force. On the contrary, it is desirable that t = 140 kg/open 2 or more. However, the alloy wire used is extremely special, which poses a problem in terms of price.Therefore, a more desirable value for the tensile strength t, which also takes into account the holding force of the terminal, is 80 to 120 kg/mm, which allows use of common materials. ” is.

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 made 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 why we chose Kaku 2 is that if the conventional product is over 0.30+w", the required strength can be obtained, but the purpose of weight reduction cannot be achieved. On the other hand, when D=0.05 or less, T is less than 5kg, This is because the 710.08φ structure is prone to deformation due to tension.A more desirable value of D is 0.07 to 0.
20 gardens 2.

Conventional annealed copper wire has a total cross-sectional area D = 0.3I due to its mechanical properties.
IIlz is the limit, and copper containing Sn (0.3 to 0.9S
Normally, D = 0.2 ms" is the limit for n), but according to the present invention, even if D = 0.1 m", it is faster than the conventional 0.3 III
It has the same strength as the III2 product, and it is possible to reduce the weight of the wire (for example, 0.1 m" is 60% less than 0.3 m").In addition, among the components of the Fe-based alloy in the extra core part, Ni, Co,
, Cr, Si, Mn, Mo, and Nb are preferably added in an amount of 20 to 80% by weight in order to ensure the necessary tensile strength and to suppress cost increases as much as possible.

That is, in general, the tensile strength of Fe-based materials increases when elements such as Ni and Cr are added. The tensile strength is, for example, Ni,
Approximately 70 to 80 kg can be produced by adding 20% or more of Co.
/-m”, and S t, Mn.

If the amount added including Cr etc. is 20% or more, the tensile strength will be approximately 100 to 140 kg/am. However, increasing the amount added does not mean that the tensile strength enhancement effect will increase proportionally. , 20 to 80% was selected as a range that would not use these expensive additive elements in vain.

In addition, generally known alloys used for the core metal in this application include, for example, 36 to 50%Ni1 about 1%Si%M
n, Fe-Ni alloys with a balance of iron and 15-25% C
r, 3 to 10% Ni, about 1% Si, Mn, and the balance is stainless steel, or high tensile strength Invar, high tensile strength stainless steel, etc. that are strengthened by adding Mo, Nb, etc. be.

[Example] 36%Ni, 1.2%MO%1. O%Mn, 0
．． 3% Si, Invar with balance Fe, 42% Ni,
1.0%Mn, 0.2%Si, balance Fe-
We prepared three types of 8ms+φ rods made of Ni alloy and 18%C, -8%Ni1 and balance Fe.We also prepared coated steel pipes with an outer diameter of 16mmφ and an inner diameter of 12mφ.
An oxygen-free copper (JIS 3510) pipe (hereinafter referred to as an OFC pipe) was prepared.

Next, in order to obtain composite conductors from these materials, the surfaces of each of the above alloy rods are dry polished (shot plus polishing).
While doing so, it was inserted into the above OFC pipe and squeezed with a fitting die to a diameter of about 10 mm.

As a result, the conductivity of samples 1 to 3 was approximately 40%, and Na4
It became a copper complex of about 65% and Ko 5 about 60%.

Therefore, these materials were repeatedly drawn and softened for 0.5 seconds.
I made it mφ. The final softening process was carried out at 600 to 900"C for about 1 hour, and then the wire was drawn so that the diameter d became 0.127 tmφ.The tensile strength t and electrical conductivity of the elementary conductor thus obtained were is as shown in the table in Figure 3.

After this, each elementary conductor is twisted into 7 wood wires and the total cross-sectional area D = 0.0
8 to 0.1 m" wire conductor, and furthermore, 0.1 m" to this.
It was coated with a two-layer thick vinyl chloride coating and made into automotive electrical wire.

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.
The number of times it takes to bend alternately at 90 degrees and break is shown as one round trip of 90'.

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 the electric wire between the inventive product and the conventional product, the total cross-sectional area D = 0.3
mm” conductor (sample N (L7), wire weight is 5.0 g/m
D=0.1mm” (sample N[L
l~5) is 1.4~1.5g/m, which is about 3.
It was possible to reduce the weight by 5g/m, or 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 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... Covered electric wire, 6... Jig, 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 elementary conductor is a composite elementary conductor whose surface layer is made of copper or copper alloy and whose core metal part is made of Fe-based Ni and Cr alloy. conductor. (2) As the elementary conductor, Ni, Co, Cr, in weight ratio,
The outer periphery of an alloy core metal containing a total of 20 to 80% of one or more selected from Si, Mn, Mo, and Nb and the remainder being iron is coated with 25 to 80% by weight of oxygen-free copper or copper alloy. The electric wire conductor for an automobile according to claim (1). (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.