JP2007023305A - Conductor element wire for electric wire for automobile, and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a conductor element wire, as a conductor wire for electric wire for automobiles, having high performance with respect to all of strength, impact resistance and electric conductivity, and also to provide its manufacturing method. <P>SOLUTION: The element wire is formed using a copper alloy having a composition consisting of, by weight, 0.03 to 0.3% Fe, 0.01 to 0.1% P and the balance Cu with inevitable impurities. In a preferable embodiment, Sn is further added. In a manufacturing process, annealing is carried out by being kept at 300 to 600°C for 0.5 to 4 h after cold wire drawing. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a conductor wire used for a core wire of an automobile electric wire such as an automobile wire harness and a method for manufacturing the same, and in particular, a conductor core wire used for a reduced-diameter automobile electric wire for weight reduction and space saving It relates to the manufacturing method.

BACKGROUND ART Wire harnesses for automobiles are widely used as electric wires for electrically connecting devices and control devices inside the automobile (for example, Patent Documents 1 to 4).
In recent years, with the improvement in performance of automobiles, the number of installed devices and control devices has increased, thereby increasing the number of wiring locations and increasing the total weight of the wire harness used. On the other hand, automobiles are being reduced in weight from the viewpoint of improving fuel consumption and saving resources, and wire harnesses are also required to be light and space-saving. One countermeasure is to reduce the conductor diameter.

Conventionally, a core wire made of seven annealed copper wires has been used for conventional electric wires for automobiles.
A point to keep in mind when reducing the diameter of the core wire is that strength and impact resistance are not inferior to those of a conventional core wire even if the diameter is reduced. In addition, it is necessary to pay attention to the bending resistance.
Strength and impact resistance are important characteristics so as not to cause disconnection during wiring harness installation or installation. In addition, the bending resistance is an important characteristic because the electric wire does not break due to vibration or the like while the vehicle is running.
The diameter of the core wire is reduced depending on whether the strand to be used is thinned or the number of strands to be used is reduced. In any aspect, the strength, impact resistance, and bending resistance of the strands are reduced. It must be improved more than before.

For the purpose of solving these problems, use different material wires such as stainless steel wires and Kevlar fibers, or use copper alloy wires such as Cu-Sn, Cu-Cr-Zr, Cu-Ni-Si, etc. Have been proposed (for example, Patent Documents 5 and 6).
However, these core wires do not completely satisfy the demands for strength, balance between improved impact resistance and improved conductivity, and cost reduction.
Accordingly, there is a demand for a conductor wire for automobile electric wires that is suitable for reducing the weight of a wire harness and that is superior in cost.
Japanese Patent No. 3275506 Japanese Patent Application Laid-Open No. 06-060739 Japanese Patent Laid-Open No. 06-187831 JP 11-224538 A Japanese Patent No. 3156381 Japanese Patent Laid-Open No. 07-192535

  The subject of this invention is providing the conductor strand which has high performance, and its manufacturing method as a conductor strand for the electric wire for motor vehicles about intensity | strength, impact resistance, and electrical conductivity.

As a result of intensive studies to solve the above problems, the present inventors have added a specific amount of Sn, more preferably by limiting the content of Fe and P to a specific range among the components of the copper alloy, Further, it has been found that a strand capable of solving the above-mentioned problems can be obtained by performing heat treatment preferably under a specific temperature condition, and the present invention has been completed.
The present invention has the following features.
(1) A conductor wire for an automobile electric wire, which is made of a copper alloy, and the copper alloy contains 0.03 to 0.3 wt% of Fe and 0.01 to 0.1 wt% of P, A conductor wire for an electric wire for an automobile, wherein the balance is Cu and inevitable impurities.
(2) The copper alloy further contains Sn in an amount of 0.5 wt% or less, and the balance obtained by removing Fe, P, and Sn from the copper alloy is Cu and inevitable impurities. The conductor wire according to (1) above.
(3) The conductor wire according to (1) or (2) above, wherein the tensile strength is 250 MPa or more and the elongation at break is 15% or more.
(4) A method for producing a conductor wire for an automobile electric wire,
Prepare a copper alloy containing 0.03-0.3 wt% Fe and 0.01-0.1 wt% P, the balance being Cu and inevitable impurities, and wire-drawing the copper alloy in the cold A wire drawing step to obtain a conductor wire having a desired wire diameter;
After the wire drawing step, a heat treatment step of performing heat treatment for maintaining the conductor wire at a temperature of 300 to 600 ° C. for 0.5 to 4 hours,
A method for producing a conductor wire for an automotive electric wire, comprising:
(5) The copper alloy prepared in the wire drawing step further contains Sn in an amount of 0.5 wt% or less, and the balance obtained by removing Fe, P, and Sn from the copper alloy is Cu and inevitable impurities. The manufacturing method according to (4) above, characterized in that it exists.

The copper alloy that is the material of the conductor wire is a Cu—Fe—P alloy (in a preferred embodiment, a Cu—Fe—P—Sn alloy), the Fe content is 0.03 to 0.3 wt%, and the P content is By setting the content to 0.01 to 0.1 wt%, it is possible to obtain a conductor wire having the same strength and impact resistance as the conventional one, while reducing the diameter.
The conductor wire formed by using one or more conductor wires is naturally thinner than the conventional wire, and the harness formed using the conductor wire as a core wire can take the same routing method as before. Car weight reduction, fuel efficiency improvement, space saving, resource saving can be achieved.

First, the conductor wire according to the present invention will be described.
The said conductor strand is a strand for forming the core wire of the electric wire for motor vehicles, Comprising: It consists of a copper alloy by which the composition was optimized so that the said subject could be achieved. One or more conductor wires are used and twisted as necessary to form a core wire for an automobile electric wire.
The basic composition of the copper alloy constituting the conductor wire is that the Fe content is 0.03 to 0.3 wt%, the P content is 0.01 to 0.1 wt%, and the balance is Cu and inevitable impurities. . Due to this basic composition, the conductor wire exhibits the above action.

Although content of Fe in the said copper alloy is 0.03-0.3 wt% (weight%), More preferably, it is 0.03-0.2 wt%, The especially preferable range is 0.05-0. 2 wt%. As the content ratio of Fe is narrowed to a particularly preferable range, the above action becomes more prominent.
If the content of Fe is appropriate, the mechanical strength of the conductor wire is mainly improved. If the Fe content is less than the lower limit of 0.03 wt%, the desired strength and impact resistance cannot be obtained when a conductor wire is formed. On the other hand, if the Fe content exceeds the upper limit of 0.3 wt%, impact resistance cannot be obtained, and the conductivity is also lowered.

Although content of P in the said copper alloy is 0.01-0.1 wt%, More preferably, it is 0.01-0.04 wt%, Most preferably, it is 0.02-0.04 wt%.
Along with Fe, the above-mentioned action becomes more prominent as the P content ratio is narrowed to a particularly preferable range. If the content of P is appropriate, the mechanical strength of the conductor wire is mainly improved. If the P content is less than the lower limit of 0.01 wt%, the desired strength and impact resistance cannot be obtained. On the other hand, if the P content exceeds the upper limit of 0.1 wt%, impact resistance cannot be obtained, and the conductivity is also lowered.

A more preferable embodiment of the copper alloy includes an embodiment in which Sn is further added in addition to Fe and P. In this case, the remainder obtained by removing Fe, P, and Sn from the copper alloy becomes Cu and inevitable impurities.
By adding Sn, an effect that the strength of the conductor wire is further improved can be obtained. The preferable addition amount of Sn is 0.5 wt% or less. When Sn is excessively added and exceeds 0.5 wt%, the conductivity tends to decrease, and it tends to be difficult to obtain impact resistance. Moreover, in order to make the effect by Sn addition remarkable, it is preferable to make Sn content 0.05 wt% or more.
From these points, the preferable range of the Sn content is 0.05 to 0.5 wt%, more preferably 0.05 to 0.3 wt%, and particularly preferably 0.05 to 0.25 wt%.

The strengthening mechanism of the conductor element wire (copper alloy element wire) is due to precipitation strengthening due to precipitation of the Fe—P compound, and the strength is further improved by adding solid solution strengthening with Sn as a preferred embodiment.
By making each content of each additive element [Fe, P, Sn added as a more preferable embodiment] within the above range, imparting strength and impact resistance and conductivity can be obtained in a well-balanced manner. Moreover, it becomes possible to manufacture a bus bar (rough drawing wire) in a stage before drawing a conductor wire having a target wire diameter by a continuous casting and rolling method.

As described above, the metals added to the copper alloy are Fe and P, and Sn added as a preferred embodiment. Ideally, the balance other than the added metal is all copper, but in reality there are inevitable impurities.
Inevitable impurities are impurities inevitably present in addition to the main elements constituting the copper alloy [Cu, Fe, P, Sn added as a more preferable embodiment], and mainly include, for example, lead, arsenic , Bismuth, oxygen and the like.
The total content of unavoidable impurities of metals such as lead, arsenic, and bismuth is preferably 0.01 wt% or less from the viewpoint of preventing the conductivity of the conductor wire from being reduced or preventing the occurrence of surface scratches, More preferably, it is 0.005 wt% or less.
Further, if oxygen is present in a large amount, it may adversely affect the strengthening mechanism of the alloying elements [Fe, P, Sn added as a more preferable embodiment] during melting and rolling of the alloy. It is desirable to keep it at a minimum.

  The wire diameter of the said conductor strand is 0.05-0.5 mm, Preferably it is 0.1-0.3 mm. By making the wire diameter of the element wire within the above range, it is possible to achieve both reduction in diameter and material strength. If the wire diameter is smaller than 0.05 mm, the tendency to make it difficult to secure the material strength of the conductor becomes stronger. If it is larger than 0.5 mm, the core wire obtained by using this becomes thicker, and there is an advantage of reducing the diameter. Disappear.

The tensile strength of the said conductor strand is 250 Mpa or more, Preferably it is 300-350 Mpa. Further, the elongation at break of the conductor element wire is 15% or more, preferably 20 to 25%.
These tensile strength and elongation at break are measured according to JIS C 3002.

In order to give the above-mentioned mechanical properties to the conductor wire, it is essential that the wire is annealed as described later after the wire is formed by cold drawing as described later.
The fact that the conductor wire is formed by cold wire drawing and is annealed after cold wire drawing means that the metal structure of the conductor wire is optical microscope. It is possible to determine by observing at. That is, the structure before annealing is a fibrous processed structure, but the structure subjected to annealing is a recrystallized structure.

In order to form an automobile electric wire conductor using the conductor wire, a necessary number of the conductor wires corresponding to the target core wire diameter is used, and a twisted wire is used as a preferred embodiment.
FIG. 1 is a schematic diagram showing an example of a cross section of an automobile electric wire conductor using the conductor wire. In the example of the figure, seven conductor wires 1 are used, which are twisted to form an automobile electric wire conductor (core wire) 2, and an insulating coating layer 3 is formed so as to cover it. ing.
When forming a stranded wire, basically, the conductor strand is made thinner than a conventional annealed copper strand, and the same seven strands as in the past are performed. In addition, by making a large number of strands of ultrafine strands, the bending resistance of the electric wire is further improved, the irregularities on the outer peripheral surface of the strands are reduced, and the cross-sectional shape of the entire conductor is nearly circular, The insulating thickness can be reduced, and the variation in the thickness of the insulating layer is reduced over the entire circumference. As a result, the wear resistance of the whole insulating layer is improved, and at the same time, the effect that the variation in the wear resistance of each part is reduced is also obtained.

In the case of forming a stranded wire, the preferred number of the conductor strands is about 7 to 50, and the strand diameter may be selected so as to be such a number.
The twisting method of the stranded wire may be a known collective twist or concentric twist. Collective twisting is simply a matter of collecting and twisting strands, and has the advantage of low manufacturing costs. In the concentric twisting, the strands are arranged concentrically and twisted so that the cross section becomes a polygonal shape or a circular shape. What is necessary is just to select these twists suitably according to a use.

Next, the manufacturing method of the said conductor strand is demonstrated.
The said manufacturing method is a preferable manufacturing method of the conductor strand by this invention demonstrated above, Comprising: As shown in said (4), it has a wire drawing process and a heat treatment process at least.

  The copper alloy to be prepared in the wire drawing step is the copper alloy described in the explanation of the conductor wire according to the present invention. That is, a Cu—Fe—P alloy, and a preferred embodiment is a Cu—Fe—P—Sn alloy to which Sn is further added. As described above, inevitable impurities may be included.

  The drawing process in the drawing process is further divided into two stages. That is, in the first wire drawing process for roughing the copper alloy material to the state of rough drawing, and in the second wire drawing process for drawing the rough drawing wire to a conductor wire having a target wire diameter in the cold state. is there.

The roughing process in the first wire drawing step may be a known processing method, but as a method for lowering the manufacturing cost, it is possible to perform casting / rolling by melting copper alloy hot water and continuous casting rolling method. preferable.
The continuous casting and rolling method is a method of continuously performing steps from melting of copper alloy hot water, casting, and rolling from an ingot to a wire rod.
The continuous casting and rolling method includes a foil belt type continuous casting and rolling method, a twin belt type continuous casting and rolling method, and a DIP method. For example, it is also possible to manufacture rough drawn wire by applying “Basics and Industrial Technology of Copper and Copper Alloys” (Japan Copper and Brass Association).

An example of the first wire drawing process is given.
First, electrolytic copper is melted in a shaft furnace or the like, and this molten copper is poured into a holding furnace, and the above-described additional elements (Fe, P, and Sn as a preferred embodiment further) are added within specified values to melt the copper alloy hot water To do.
Next, casting and rolling are performed by the continuous casting and rolling method using the molten copper alloy (that is, continuous casting and hot rolling is performed using the molten copper alloy) to obtain a rough drawn wire.
The wire diameter of the rough drawn wire is not particularly limited, but is preferably about 6 to 13 mm.

  It is also possible to cast a molten copper alloy similar to the above by a water-cooled casting method, and obtain a desired rough drawn wire by hot extrusion and hot rolling. However, in this method, the number of steps increases, so that the manufacturing cost increases, and the price of the conductor wire becomes higher compared to the case of the continuous casting and rolling method.

In the second wire drawing step, the rough drawing wire obtained as described above is subjected to cold wire drawing to increase the strength due to the processing effect and finish to the target wire diameter.
The cold wire drawing method itself may use a known technique, and wire drawing by a die is generally used, but rolling, swaging, or the like may be applied.
Cold wire drawing means performing wire drawing, rolling, swaging, etc. with the above-mentioned die on a rough drawn wire held at room temperature (for example, 5 to 35 ° C. according to JIS Z 0050). It is.

The cross-sectional shape of the conductor wire is generally a circular shape, but may be a square shape or a different shape such as a sector depending on the purpose.
As a device used for cold wire drawing, a slip-type continuous wire drawing machine is generally used, but a non-slip type wire drawing machine may be used.

In the heat treatment step, heat treatment is performed on the copper alloy wire obtained by the cold step.
This heat treatment is carried out mainly for the purpose of improving impact resistance. The temperature of the heat treatment is preferably 300 to 600 ° C, more preferably 450 to 550 ° C. When the heating temperature is lower than 300 ° C., the elongation and the conductivity are lowered, and when the heating temperature is higher than 600 ° C., the tensile strength is lowered. A decrease in elongation and tensile strength is not preferable because it causes a decrease in impact resistance.
The heat treatment time is preferably 0.5 to 4 hours, more preferably 0.5 to 2 hours. When the heat treatment time is shorter than 0.5 hours, the elongation and conductivity are low, and when it is longer than 4 hours, the tensile strength is low.

  A known method may be used for annealing, and current annealing is preferable from the viewpoint of productivity, but may be annealing through a tubular furnace, batch annealing, or the like.

In this example, conductor wires are formed using copper alloys in which the contents of Fe, P, and Sn are changed to various values, and further, those subjected to heat treatment and those not subjected to heat treatment are prepared. The performance was observed, and it was investigated whether the set value of the content of the conductor wire according to the present invention and the presence or absence of heat treatment had a critical significance.
As the content of Fe, P, Sn falls within the specified range according to the present invention, Example Product No. 1-10 were produced.
Moreover, any one of the contents of Fe, P, and Sn deviates from the specified range according to the present invention. 11-19 were produced. In addition, although the contents of Fe, P, and Sn belong within the specified range according to the present invention, as a sample not subjected to heat treatment, Comparative Example No. 20-29 were produced.
Furthermore, a copper alloy wire shown in Japanese Patent No. 3275506 was manufactured, and the performance was compared with the product of this example as a comparative product (No. 30, 31,).
Comparative product No. 32 is a conventionally known annealed copper wire, which is produced by drawing a tough pitch copper rough drawn wire produced by a continuous casting and rolling method and subjecting it to a heat treatment.

[Production of Examples 1 to 10 and Comparative Examples 11 to 29]
The electrolytic copper was melted in a shaft furnace, this molten copper was rolled into a holding furnace, and alloy elements were added at a predetermined ratio shown in Table 1 to melt the molten copper alloy.
Next, the molten copper alloy was continuously cast and rolled by a foil belt type continuous casting and rolling method to obtain a copper alloy rough drawn wire having a wire diameter of 8 mm.
The obtained rough drawn wire was subjected to cold working with a drawing die using a continuous wire drawing machine to obtain a copper alloy strand having a wire diameter of 0.22 mm.
Among the obtained copper alloy strands, Examples 1 to 10 and Comparative Examples 11 to 19 were subjected to a heat treatment (annealing) for 1.5 hours in a nitrogen atmosphere at a temperature of 500 ° C. .

[Evaluation]
Tensile strength, electrical conductivity, and impact resistance were measured for the conductor wires of Examples 1 to 10 and Comparative Examples 11 to 32. The evaluation methods were as follows.
Chemical composition: Analytical method defined in JIS H 3250 (copper and copper alloy bar) Tensile strength: JIS Z 2241 (Tensile test method for metal material)
Conductivity: JIS H 0505 (volume resistivity and conductivity measuring method of non-ferrous metal material)
Impact resistance: A tensile test was conducted at a tensile speed of 1 m / sec using a high-speed tensile tester, and the impact absorption energy was determined from the area surrounded by the obtained stress-strain curve.

  Table 2 summarizes the evaluation results. Here, as for impact resistance, those superior to the conventional annealed copper wire (No. 32) are indicated by ◎, equivalents are indicated by ○, and inferior ones are indicated by ×. The conductivity required for the electric wire for automobiles is assumed to be 70% or more.

As is apparent from the evaluation results in Table 2, the example product (conductor wire according to the present invention) has superior impact resistance compared to the conventional annealed copper wire (No. 32), and is an electric wire for automobiles. As a result, it was confirmed that necessary conductivity was secured.
Comparative product No. Although the copper alloy wires 30 and 31 have the same strength and impact resistance as the products of the present invention, the electrical conductivity is as low as 58 to 65% and does not satisfy the electrical conductivity required for electric wires for automobiles. I understood it.

According to the present invention, it is possible to provide a conductor wire having high performance with respect to any of strength, impact resistance, and conductivity.
Moreover, the said conductor strand was twisted together and the preferable electric wire conductor for motor vehicles was obtained.

It is the schematic diagram which showed an example of the cross section of the electric wire for motor vehicles formed using the conductor strand by this invention.

Explanation of symbols

1 Conductor Wire 2 Core Wire 3 Insulation Covering Layer

Claims (5)

  A conductor wire for an electric wire for an automobile, which is made of a copper alloy, the copper alloy contains 0.03 to 0.3 wt% of Fe, 0.01 to 0.1 wt% of P, and the balance is Cu Conductor strands for electric wires for automobiles, characterized in that they are inevitable impurities.   The copper alloy further contains Sn in an amount of 0.5 wt% or less, and the balance obtained by removing Fe, P, and Sn from the copper alloy is Cu and inevitable impurities. 1. A conductor wire according to 1.   The conductor wire according to claim 1 or 2, wherein the tensile strength is 250 MPa or more and the elongation at break is 15% or more. A method for manufacturing a conductor wire for an electric wire for an automobile,
Prepare a copper alloy containing 0.03-0.3 wt% Fe and 0.01-0.1 wt% P, the balance being Cu and inevitable impurities, and wire-drawing the copper alloy in the cold A wire drawing step to obtain a conductor wire having a desired wire diameter;
After the wire drawing step, a heat treatment step of performing heat treatment for maintaining the conductor wire at a temperature of 300 to 600 ° C. for 0.5 to 4 hours,
A method for producing a conductor wire for an automotive electric wire, comprising:   The copper alloy prepared in the wire drawing step further contains Sn in an amount of 0.5 wt% or less, and the balance obtained by removing Fe, P, and Sn from the copper alloy is Cu and inevitable impurities. The manufacturing method according to claim 4, wherein the manufacturing method is characterized.

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