JP3768899B2 - Precipitation strengthened copper alloy trolley wire and manufacturing method thereof - Google Patents

Description

【００３１】
トロリ線の完成品としては、引張り強さが５７０ＭＰａ以上、かつ、導電率が７５％ＩＡＣＳ以上のものが合格品とされる。当該基準では、実施例１（完成品）のみが合格品であることが表１から明らかである。
【００３２】
【発明の効果】
本発明に係る製造方法においては、（Ｃ）時効熱処理工程の後に（Ｄ）第２の冷間加工工程に供することで、高強度化を達成することができ、導電率の低下も最小限に抑えることができる。また、従来の方法に比べて加熱する工程が増加するわけではないので、トロリ線の製造コストを大幅に増大させずに、高強度のトロリ線を製造することができる。
【図面の簡単な説明】
【図１】従来技術における、析出強化型銅合金トロリ線の製造フローを示す図である。
【図２】本発明の析出強化型銅合金トロリ線の製造フローを示す図である。
【図３】本発明の製造方法における各製造工程の温度の推移を例示する図である。
【符号の説明】
Ａ 溶体化処理工程
Ｂ 第１の冷間加工工程
Ｃ 時効熱処理工程
Ｄ 第２の冷間加工工程[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a precipitation-strengthened copper alloy trolley wire and a method for producing the same.
[0002]
[Prior art]
The trolley line is an electric wire that is installed at the bottom of the overhead line of the train and sends power to the train in contact with the pantograph. In order to respond to the recent demand for higher speed of the Shinkansen and longer life by improving the wear resistance of the trolley wire, the trolley wire is required to have higher strength and higher electrical conductivity. As a trolley wire satisfying such requirements, a trolley wire made of an aging copper alloy (precipitation strengthened copper alloy) (hereinafter referred to as “precipitation strengthened copper alloy trolley wire” or simply “trolley wire”) has been proposed. (See JP-A-7-266939).
[0003]
Precipitation-strengthened copper alloy trolley wire is at least (A) solution treatment process and (B) cold-worked rough drawn wire obtained by melting, forging, rolling, extruding, etc. from raw materials (copper base material and additive elements, etc.) It is a trolley wire obtained through three steps of step, (C) aging heat treatment step (see FIG. 1). In the step (A), in order to uniformly dissolve the elements (Zr, Cr, Si, etc.) added in the copper base material, heat treatment is performed at a high temperature (about 800 to 1050 ° C.), and then poured into water or the like. This is a rapid cooling process. Step (B) is a step of subjecting the rough drawn wire cooled to about room temperature to processing such as die drawing or roll rolling. The step (C) is a step of improving the tensile strength and the electrical conductivity by precipitating the additive element dissolved in the copper base material in the step (A) by the heat treatment after the step (B).
[0004]
The precipitation-strengthened copper alloy trolley wire is a trolley wire intended to improve strength and conductivity by precipitating the alloy element (additive element) dissolved in the step (A) in the step (C). It is. However, although the trolley wire can obtain good conductivity, it may not obtain the desired strength. As desired conductivity and tensile strength, for example, in the case of a trolley wire having a cross-sectional area of 110 mm ² , the conductivity is 75% IACS or more and the tensile strength is 570 MPa or more.
[0005]
As a conventional technique for increasing the strength of the trolley wire, firstly, there is a method of increasing the degree of processing in the step (B), that is, a method of increasing the cross-section reduction rate by performing more processing in the cold processing step. . However, in the case of this method, it is necessary to increase the diameter of the rough drawing wire before the cold working process, which makes it difficult to handle the material, and in some cases, requires new equipment investment. It is not preferable.
[0006]
As a second prior art for increasing the strength of the trolley wire, there is a method of performing aging heat treatment twice as described in JP-A-6-1554838. However, this method is not preferable because it increases the number of heat treatments and increases costs.
[0007]
[Problems to be solved by the invention]
An object of the present invention is to provide a method for producing a precipitation-strengthened copper alloy trolley wire that is lower in cost and higher in strength than in the past.
[0008]
[Means for Solving the Problems]
The precipitation-strengthened copper alloy has been thought to be effective to be subjected to an aging heat treatment in the final process of production, and therefore there has never been an idea that further processing is performed after the (C) aging heat treatment process. However, when trying to perform cold working again (hereinafter referred to as “(D) second cold working step”) after the step (C), the decrease in conductivity is surprisingly small, and It was found that the strength was improved. The present inventors have completed the present invention based on such knowledge.
[0009]
That is, the present invention has the following features.
(1) at least, solution heat treatment step, a first cold working step, the aging heat treatment process, have a second cold working step, the cold working of at least a circular during the first cold working step A method for producing a precipitation-strengthened copper alloy trolley wire , which is deformed and has a workability of 10 to 20% in the second cold working step .
( 2 ) A precipitation-strengthened copper alloy trolley wire produced by the method described in ( 1) .
(3) Cr is 0.1-0.5%, Zr is 0.01-0.2 wt%, Si is at 0.01～0.05Wt%, the balance being copper and inevitable impurities, (2), wherein Precipitation strengthened copper alloy trolley wire.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the manufacturing method of the trolley wire of this invention is demonstrated. The production flow of the trolley wire of the present invention is shown in FIG. 2, and an example of the transition of the processing temperature in the production is shown in FIG.
[0011]
In the present invention, the precipitation-strengthened copper alloy trolley wire (or simply “trolley wire”) means that at least the above-described (A) to (C) by adding a precipitation type additive element such as Cr, Zr or Si to a copper base material. ) Means a trolley wire that has undergone the above process. The manufacturing method of the trolley wire is a process in which steps (A) and (C) are further added to conventional pure copper and solid solution strengthened copper alloys (Sn-containing copper alloys, etc.) that undergo only the step (B). However, it is a method that can obtain a trolley wire having higher strength and higher electrical conductivity.
[0012]
The trolley wire according to the present invention is a trolley wire made of a copper alloy containing Cr, Zr, and Si in at least Cu. From the viewpoint of balance between strength and conductivity, the Cr content is preferably 0.1 to 0.5 wt%, more preferably 0.25 to 0.45 wt%, and the Zr content is preferably 0.01. It is -0.2 wt%, More preferably, it is 0.05-0.15 wt%, Content of Si becomes like this. Preferably it is 0.01-0.05 wt%. The remainder other than these additives is preferably all copper, but may contain inevitable impurities such as oxygen, As, Pb, and Sb. The total content of the inevitable impurities is preferably 0.01 wt% or less, more preferably 0.005 wt% or less, from the viewpoint of preventing a decrease in conductivity. However, since the presence of oxygen atoms significantly reduces the tensile strength, the oxygen atoms are preferably 0.001 wt% or less.
[0013]
As a raw material used in the production method of the present invention, a conventionally known copper alloy raw material can be arbitrarily used. For example, the above-mentioned additive elements can be added using electrolytic copper as a raw material.
[0014]
These raw materials are preferably heated and melted and stirred in a non-oxidizing atmosphere, and then the obtained copper alloy molten metal is cast into a mold to obtain a billet or cake. Then, the method of obtaining a rough drawing line by well-known hot rolling, for example, rolling using a rolling roll etc. at 300-700 degreeC is mentioned. There is also a method of obtaining rough drawn lines by hot extrusion using an extruder instead of hot rolling. Further, the rough drawn wire may be manufactured by a continuous casting and rolling method in which melting, casting, and hot rolling are continuously performed.
[0015]
Thereafter, the rough drawn wire is subjected to the step (A), that is, the solution treatment step. In this step, a conventionally known method may be used. For example, the obtained drawn wire is heated to 800 to 1050 ° C., preferably 900 to 1000 ° C., so that the additive element is dissolved in the solution and then poured into a water tank or the like at room temperature (according to JIS K 0050). Cool to 5 to 35 ° C.).
[0016]
The rough drawn wire whose temperature has dropped to room temperature is subjected to (B) a cold working step (hereinafter, referred to as “first cold working step” in order to distinguish it from the (D) step). The process can be performed by any known method, for example, a die drawing method, a roll rolling method, a swaging method, and the like, but is not limited thereto. Usually, during this step (B), at least a cold work in a circular shape and an irregular shape unique to a trolley wire are performed. In addition, during the step (B), a so-called “peeling” treatment is performed, in which a surface layer of 0.1 to 0.5 mm, preferably 0.1 to 0.2 mm, is removed from the surface using a die or the like. Is preferable from the viewpoint of improving the surface smoothness.
[0017]
Here, as an index representing the degree of processing by various processes in the step (B), the concept of “processing degree” is defined by the following equation.
Degree of processing (%) = 100 × (A−B) / A
Here, A is a cross-sectional area before processing, and B is a cross-sectional area after processing.
[0018]
In the present invention, the degree of work in the first cold working step (B) is preferably 50 to 90%, and more preferably 70 to 90%. In the present invention, since the cold working process is performed twice (that is, the process (B) and the process (D) described later) or more, if the degree of processing at each time is too large, the number of processes increases, resulting in high costs. Therefore, it is not preferable. On the other hand, if the degree of processing is too small, the desired strength cannot be obtained.
[0019]
Following the step (B), (C) an aging heat treatment step is performed. The aging heat treatment step is a treatment for improving strength and conductivity by precipitating alloy components by heat treatment as will be described later. (C) In a process, it heats at 350-550 degreeC, Preferably it is 400-500 degreeC. When the heating temperature is lower than 350 ° C., the alloy components are not sufficiently precipitated, and improvement in strength and electrical conductivity cannot be expected. Conversely, at a temperature higher than 550 ° C., there is a concern that improvement in tensile strength cannot be expected. is there.
[0020]
Subsequently, it hold | maintains at the said temperature for 0.5 to 4 hours, Preferably it is 1-3 hours. If the holding time is shorter than 0.5 hours, the alloy components are not sufficiently precipitated, and improvement in strength and electrical conductivity cannot be expected. Conversely, if the holding time is longer than 4 hours, the energy consumption during manufacturing is large and the manufacturing cost is high. There is a concern that will increase.
[0021]
As described above, the present invention is characterized by having (D) the second cold working step after the steps (A) to (C). The process (D) is the same as the process (B) described above, and is a process of performing processes such as die drawing, roll rolling, and swaging at room temperature.
[0022]
From the viewpoint of realizing cost reduction by minimizing the loss of raw materials, obtaining the desired strength, and minimizing the decrease in conductivity, the degree of processing in the step (D) is 10 to 30%. And is more preferably 10 to 20%. In this way, the strength can be increased by work hardening by subjecting it to the cold working step after the step (C). At this time, although there is a slight decrease in conductivity, the decrease is within an allowable range for the trolley wire.
[0023]
【Example】
EXAMPLES Hereinafter, although this invention is demonstrated further in detail based on an Example, this invention is not limited only to an Example.
[0024]
Example 1
In order to produce a trolley wire consisting of 0.3 wt% Cr, 0.1 wt% Zr, 0.04 wt% Si, and Cu and inevitable impurities (50 ppm or less) as the final composition, the following processing is performed. Was given.
[0025]
First, electrolytic copper was heated to 1500 ° C. in a reducing atmosphere (Ar gas) and melted, and after adding metal Cr, metal Zr, and metal Si, it was cast into a billet shape. Subsequently, rough drawing wire (diameter of 30 mm in cross section) was obtained using a rolling roll as hot rolling (400 ° C.). (A) As the process, the rough drawn wire is heated at 950 ° C. for 1 hour, and then rapidly cooled by water cooling. As the process (B), cold working with a work degree of 81% is performed by die drawing. A scale trolley wire (before aging heat treatment (before step (C)) was obtained. At this time, a surface layer of about 0.1 mm was cut from the surface using a skinning die as a skinning step. Next, as step (C), the trolley wire before aging heat treatment was heated at 500 ° C. for 2 hours (aging heat treatment).
[0026]
Thereafter, a trolley wire was obtained by performing a process with a processing degree of 15% by die drawing as a step (D) at room temperature.
[0027]
(Comparative Example 1)
A trolley wire was obtained by the same method as in Example except that the degree of processing in the step (B) was 84% and the step (D) was not performed.
[0028]
(Evaluation)
The strength (tensile strength) and conductivity of the trolley wire 100 cm of Example 1 and Comparative Example 1 were measured. In addition, the same measurement was performed by sampling 100 cm at the stage of the manufacture of Example 1 (after completion of the steps (B) and (C)).
[0029]
The tensile strength was measured based on JIS Z 2241, and the electrical conductivity was measured based on JIS H0505. The results are summarized in Table 1.
[0030]
[Table 1]

[0031]
As a finished product of the trolley wire, a product having a tensile strength of 570 MPa or more and a conductivity of 75% IACS or more is regarded as an acceptable product. It is clear from Table 1 that only Example 1 (finished product) is an acceptable product based on this standard.
[0032]
【The invention's effect】
In the manufacturing method according to the present invention, (C) the aging heat treatment step is followed by (D) the second cold working step, whereby high strength can be achieved and the decrease in conductivity is also minimized. Can be suppressed. Moreover, since the heating process does not increase compared to the conventional method, a high-strength trolley wire can be manufactured without significantly increasing the manufacturing cost of the trolley wire.
[Brief description of the drawings]
FIG. 1 is a diagram showing a manufacturing flow of a precipitation strengthened copper alloy trolley wire in the prior art.
FIG. 2 is a view showing a manufacturing flow of a precipitation-strengthened copper alloy trolley wire of the present invention.
FIG. 3 is a diagram illustrating temperature transition of each manufacturing process in the manufacturing method of the present invention.
[Explanation of symbols]
A Solution treatment step B First cold working step C Aging heat treatment step D Second cold working step

Claims (3)

At least, the solution treatment step, a first cold working step, the aging heat treatment process, have a second cold working step, at least cold working circular and irregular processing in the first cold working step The manufacturing method of the precipitation-strengthening-type copper alloy trolley line | wire which is performed and the workability in a 2nd cold working process is 10 to 20% . A precipitation strengthened copper alloy trolley wire produced by the method according to claim 1 . The precipitation strengthening according to claim 2 , wherein Cr is 0.1 to 0.5 wt%, Zr is 0.01 to 0.2 wt%, Si is 0.01 to 0.05 wt%, and the balance is made of copper and inevitable impurities. Type copper alloy trolley wire.

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