【発明の詳細な説明】[Detailed description of the invention]
〔発明の属する技術分野〕
本発明は真空しや断器に用いられるCu−Cr接
点材料の製造方法の改良に関する。
〔従来技術とその問題点〕
一般に真空しや断器は次のような特徴を有して
いる。
１ 電流しや断を真空容器内で行い、電流自然零
値時における消イオン作用が、高真空中の電子
の拡散によるため、他の消弧原理のものに比べ
て著しく大きく、すぐれたしや断性能を示す。
２ しや断時にアークが露出しないので、火災や
爆発の危険性がなく安全である。
３ 小型、軽量にでき保守点検の省力化に役立
つ。
４ しや断時の騒音が少い。
５ 接点が真空中に密封されているので雰囲気の
影響を受けず保守の必要がない。
６ 接点を開閉する機器以外は特に補助装置や付
属品を必要としない。
以上のような幾多の特徴を備えているために、
真空しや断器は、一般産業、ビルや工場の受配電
設備への需要が増加しており、さらに利用範囲の
拡大が図られている。
この真空しや断器に使用される接点材料の選定
は重要であり、通常接点材料としては次のような
特性が要求されている。
(1) 十分に脱ガスされていること。
(2) 電気伝導、熱伝導が良いこと。
(3) 消耗が少なく溶着をしないこと。
(4) しや断性能がすぐれていること。
(5) 接触抵抗が小さく通電容量が大きいこと。
(6) 耐圧が高いこと。
(7) さい断電流が小さいこと。
(8) 機械加工性に富み、形状付与性に優れるこ
と。
これらのうちとくにさい断電流は真空しや断器
の特徴的現象として短所ともなつているものであ
つて、小電流をしや断するとき電流が自然零点と
なる以前にアークを安定に維持することができず
に急激に消滅するという問題があるために、真空
しや断器を用いた誘導性回路などでは異常電圧が
発生して機器の絶縁劣化を生じ、機器損傷の原因
となるので、この種の用途ではさい断電流値の小
さいことが要求されるが、この特性は殆ど接点材
料によつて左右される。
以上のことから大電流しや断性能を有し、耐溶
着、さい断電流特性にすぐれた真空しや断器用接
点の適切な材料選定が望まれているがこれら要求
特性は相反関係をなすものもあるので全てを満足
する接点材料を得ることはむづかしく、それぞれ
の用途に応じてとくに重要な特性を満たし、その
他の特性は若干犠牲にする使用例が多い。
例えば従来用いられているこの種の接点材料の
代表的なものとしてCu−Bi系合金やCu−Cr系合
金などがよく知られている。これらのうちCu−
Bi系合金はしや断性能、耐溶着性などの点です
ぐれているが、この合金中に含まれているBiが
真空しや断器の耐電圧特性を劣化させる要因にな
りやすく、またさい断電流値も低いが、大電流し
や断を繰り返すことによりBiの浸み出しや蒸発
が盛んになつて次第にさい断電流特性が悪化する
ようになるなどの欠点をもつている。一方Cu−
Cr系合金は元来CuとCrが互に溶融し難いために、
Cr粉末の焼結体に溶融Cuを浸透させて得られる
ものであり、この合金中に占めるCrの割合は20
〜60重量％が普通である。このCu−Cr系合金は
しや断性能、耐電圧特性、さい断電流特性が相対
的にすぐれ、しかもこの合金の構成元素となつて
いるCrがガスを吸収するゲツター作用を有する
ため、真空しや断器用接点として有効であること
が一般に認められている。しかしながらCu−Cr
系合金の耐溶着性はCu−Bi系合金より劣るとい
う欠点がある。Cuを主成分とした接点材料を所
要の真空しや断器用接点の形状に加工する際に
は、Cuが粘いため切削しずらく、加工時間が長
くなりかつ切削工具の寿命も短くなりやすい問題
がある。さらに、Cr焼結体にCuを溶浸したCu−
Cr系接点材料においても、CuとCrの界面の接合
が比較的強いので、機械加工性はそれほど良好で
なく、Cuの粘さと延性により切削時の切粉が細
長く連続し、切削速度を上げることが困難である
問題がある。
〔発明の目的〕
本発明は上述の点に鑑みてなされたものであ
り、その目的は耐溶着性とさい断電流特性にすぐ
れかつ機械加工性にすぐれた真空しや断器用Cu
−Cr接点材料の製造方法を提供することにある。
〔発明の要点〕
本発明に係る接点材料はCuが45〜60％、Teが
0.05〜４％、残部がCrからなるCu−Cr−Te合金
であり、Cr焼結体にCu−Te合金を溶浸すること
により得られるものである。
〔発明の実施例〕
以下本発明を実施例に基づき説明する。
通常Cu−Cr合金を製造するには前述したよう
に焼結溶浸法が用いられ、例えばまずCr粉末を
黒鉛鋳型に充てんし、これを1200〜1350℃で数時
間真空焼結してCr焼結体とし、このCr焼結体に
真空中1100〜1250℃でCuを溶浸する。本発明の
合金を得るためには基本的にはこの方法と変らな
いがTeを添加するためにCuの代りにCu−Te合
金を用いた。Teを添加したのはCu−Cr合金の中
に脆弱なTeを均一微細に分散させることにより
接点の溶着現象が起りにくくなることと、Teが
CuやCrに比べて蒸気圧が高いので電流しや断時
のアークを持続させるためにさい断電流値を低く
する効果が得られることが別途実験結果からわか
つていたからである。本発明ではまず100メツシ
ユ以下325メツシユ以上の粒径を有するCr粉末を
内径65mmφ、深さ25mmの黒鉛鋳型に振動を与えな
がら充填し、これを1250℃で１時間真空焼結して
空孔率50％のCr焼結体を得、このCr焼結体に前
もつて真空溶解により作製しておいたCu−0.1％
Te、Cu−１％Te、Cu−３％Te、Cu−５％Te、
Cu−８％TeのTe含有量の異なる５種のCu−Te
合金をそれぞれ真空雰囲気中1200℃で溶浸させ
Teの最適含有量を求めた。この際Cr焼結体の空
孔率はCr粉末の焼結温度を1100〜1400℃の範囲
で設定することにより45〜55％の範囲とすること
ができ、この範囲の空孔率で前述の５種類のCu
−Te合金を溶浸するとCu−Cr合金に対するCuの
含有量も決められ45〜60％となる。
このようにして得られた５種類のCu−Cr−Te
合金の化学成分と物理的性質を第１表に示す。第
１表には比較のためCr焼結体に真空溶解したCu
を溶浸して得られる従来合金についても併記して
あるが、No.１〜No.５は本発明合金でありNo.６が従
来合金である。
[Technical field to which the invention pertains] The present invention relates to an improvement in a method for manufacturing a Cu--Cr contact material used in a vacuum shield circuit breaker. [Prior art and its problems] Generally, a vacuum shield disconnector has the following characteristics. 1 The current is cut off in a vacuum chamber, and the ionization effect at the natural zero value of the current is due to the diffusion of electrons in a high vacuum, so it is significantly larger and has superior ionization compared to those using other arc-extinguishing principles. Indicates breaking performance. 2. Since the arc is not exposed when the flame is cut off, there is no risk of fire or explosion and it is safe. 3. Compact and lightweight, helping to save labor during maintenance and inspection. 4. Less noise when the sheath is turned off. 5. Since the contacts are sealed in a vacuum, they are not affected by the atmosphere and do not require maintenance. 6 No special auxiliary equipment or accessories are required other than the equipment that opens and closes the contacts. Due to the many features mentioned above,
There is an increasing demand for vacuum shields and disconnectors for power distribution equipment in general industries, buildings, and factories, and the range of use is being expanded further. The selection of the contact material used in this vacuum shield and disconnector is important, and contact materials are usually required to have the following characteristics. (1) The gas must be sufficiently degassed. (2) Good electrical and thermal conductivity. (3) Less wear and tear and no welding. (4) Excellent shearing performance. (5) Low contact resistance and high current carrying capacity. (6) High pressure resistance. (7) Small cutting current. (8) Excellent machinability and formability. Among these, the breaking current is a characteristic phenomenon of vacuum circuit breakers, which is also a disadvantage.When cutting a small current, the arc is maintained stably before the current reaches its natural zero point. As a result, abnormal voltage is generated in inductive circuits using vacuum shields and disconnectors, causing insulation deterioration of equipment and causing equipment damage. This type of application requires a small breaking current value, but this characteristic is largely determined by the contact material. From the above, it is desired to select an appropriate material for vacuum shield contacts that have high current breaking performance, excellent welding resistance, and cutting current characteristics, but these required properties are in a contradictory relationship. Therefore, it is difficult to obtain a contact material that satisfies all of the requirements, and there are many usage examples in which the characteristics that are particularly important for each application are satisfied, while other characteristics are sacrificed to some extent. For example, Cu--Bi alloys and Cu--Cr alloys are well known as typical contact materials of this type that have been conventionally used. Of these, Cu−
Bi-based alloys are excellent in terms of breaking performance and welding resistance, but the Bi contained in this alloy tends to deteriorate the withstand voltage characteristics of vacuum breakers and Although the cut-off current value is low, it has the disadvantage that repeated high-current cycles increase the leaching and evaporation of Bi, which gradually deteriorates the cut-off current characteristics. On the other hand, Cu−
In Cr-based alloys, Cu and Cr are originally difficult to melt together, so
It is obtained by infiltrating molten Cu into a sintered body of Cr powder, and the proportion of Cr in this alloy is 20
~60% by weight is common. This Cu-Cr alloy has relatively excellent breaking performance, withstanding voltage properties, and breaking current properties, and since Cr, which is a constituent element of this alloy, has a getter action that absorbs gas, it can be used in vacuum. It is generally accepted that it is effective as a disconnector contact. However, Cu−Cr
The disadvantage of this type of alloy is that its welding resistance is inferior to that of the Cu-Bi type alloy. When processing a contact material containing Cu as a main component into the desired shape of a vacuum or disconnection contact, the problem is that Cu is sticky and difficult to cut, resulting in long processing times and shortening the life of the cutting tool. There is. In addition, we have developed a Cu− infiltrated Cr sintered body
Even in Cr-based contact materials, the bond between the Cu and Cr interfaces is relatively strong, so the machinability is not very good, and the viscosity and ductility of Cu causes the chips to become long and thin during cutting, increasing the cutting speed. There is a problem that is difficult. [Object of the Invention] The present invention has been made in view of the above-mentioned points, and its purpose is to provide a Cu material for vacuum insulation breakers that has excellent welding resistance and cutting current characteristics, and has excellent machinability.
-Providing a method for manufacturing Cr contact material. [Summary of the Invention] The contact material according to the present invention contains 45 to 60% Cu and 45% to 60% Te.
It is a Cu-Cr-Te alloy consisting of 0.05 to 4% Cr and the balance is Cr, and is obtained by infiltrating a Cu-Te alloy into a Cr sintered body. [Examples of the Invention] The present invention will be described below based on Examples. Normally, the sintering infiltration method is used to manufacture Cu-Cr alloys, as described above. For example, Cr powder is first filled into a graphite mold, which is then vacuum sintered at 1200 to 1350°C for several hours to sinter the Cr. This Cr sintered body is infiltrated with Cu at 1100 to 1250°C in vacuum. In order to obtain the alloy of the present invention, the method was basically the same as this, but a Cu--Te alloy was used instead of Cu to add Te. The reason for adding Te is that by uniformly and finely dispersing the brittle Te in the Cu-Cr alloy, welding of the contacts becomes less likely to occur.
This is because separate experimental results showed that since it has a higher vapor pressure than Cu or Cr, it is effective in lowering the breaking current value in order to sustain the arc when the current is interrupted. In the present invention, first, Cr powder having a particle size of 100 meshes or less and 325 meshes or more is filled into a graphite mold with an inner diameter of 65 mmφ and a depth of 25 mm while being vibrated, and then vacuum sintered at 1250°C for 1 hour to reduce the porosity. A 50% Cr sintered body was obtained, and Cu-0.1%, which had been previously prepared by vacuum melting, was added to this Cr sintered body.
Te, Cu-1%Te, Cu-3%Te, Cu-5%Te,
Five types of Cu-Te with different Te contents of Cu-8%Te
Each alloy was infiltrated at 1200℃ in a vacuum atmosphere.
The optimal content of Te was determined. At this time, the porosity of the Cr sintered body can be set in the range of 45 to 55% by setting the sintering temperature of the Cr powder in the range of 1100 to 1400℃, and with the porosity in this range, the above-mentioned 5 types of Cu
Infiltration of -Te alloy also determines the Cu content relative to Cu-Cr alloy, which is 45-60%. Five types of Cu-Cr-Te obtained in this way
The chemical composition and physical properties of the alloy are shown in Table 1. Table 1 shows Cu vacuum melted in a Cr sintered body for comparison.
Conventional alloys obtained by infiltrating are also listed, and No. 1 to No. 5 are the alloys of the present invention, and No. 6 is the conventional alloy.
【表】
第１表から本発明のCu−Cr−Te合金は従来の
Cu−Cr合金と比べて物理的性質は導電率がやや
低目であるがほぼ同等と見做すことができる。次
に、本発明におけるCu−Cr−Te合金の破断面の
微視組織を顕微鏡で観察すると、大部分のTeが
CuとCr粒子の界面に粒状の状態で存在し、残り
の一部がCu基地中に分散していることが確認さ
れた。
本発明のCu−Cr−Te合金と従来のCu−Cr合
金とについて、切削加工によつて後述する溶着試
験片および接点形状を採取する際の加工性を比較
した。
本発明のCu−Cr−Te合金の切粉は連続せず、
短い鱗片状となり加工性は非常に良好であつた。
本発明のCu−Cr−Te合金の加工時間を１とする
と、従来のCu−Cr合金のそれは1.5〜1.6倍であ
り、また切削工具の磨耗率も従来合金に比べて、
本発明の合金の方が約30％低位であつた。
上記のように、本発明の接点材料は、機械加工
性がよく形状付与性に優れるものであることが確
認されたが、これは、大部分のTeがCuとCr粒子
の界面に粒状の状態で存在する合金の組織に起因
するものである。
次にこれらの合金から直径15mm、高さ10mm、先
端径が100Rの溶着試験片を採取し、溶着試験機
を用いて溶着力を測定した。試験条件は試験片の
接触力８Kg、真空度５×10-4torr、通電電流は
2kAから1kAのステツプで順次上昇させ通電後の
10kAまでの溶着力を測定したものであり、その
結果を第１図に示す。第１図は溶着力と試験電流
値との関係を表わした線図であり、第１表に示し
たNo.と第１図の各曲線に付したNo.とが対応してい
る。第１図にも従来合金No.６をプロツトしてある
が、本発明の合金は溶着力に大巾な差がないので
試験電流10kAにおける最大の溶着力を示すNo.１
と最低の溶着力を示すNo.４およびその中間的な値
を示すNo.３の３本の曲線のみをあげ、No.２とNo.５
は曲線が錯そうして判別しにくい部分が生ずるの
で省略してある。第１図は本発明の合金が従来合
金に比べて溶着力は著しく低く、接点が溶着して
も容易に開離するのに対し、従来合金は電流増加
とともに増々強固に溶着することを示しており、
第１図から本発明の合金が耐溶着性に勝ることが
わかる。
次にさい断電流値は定格7.2kV／8kAの真空バ
ルブに組込んで測定し本発明合金と従来合金を比
較した。接点寸法は外径25mm、内径13mmであり、
接点間隙は６mm、接触荷重は20Kg、真空度は
10-6torrであつて試験条件は試験電圧AC300V、
しや断電流30.5Aピーク、開極位相90°とした。試
験回数はいずれも50回行つたがさい断電流値の最
大、最小および平均値で示すと第２表の結果を得
た。第２表に示すNo.は第１表のNo.と対応してい
る。第２[Table] From Table 1, the Cu-Cr-Te alloy of the present invention is
Although the physical properties are slightly lower in electrical conductivity than Cu-Cr alloys, they can be considered to be almost the same. Next, when the microstructure of the fracture surface of the Cu-Cr-Te alloy in the present invention was observed with a microscope, most of the Te was
It was confirmed that it exists in a granular state at the interface between Cu and Cr particles, and the remaining part is dispersed in the Cu base. The Cu-Cr-Te alloy of the present invention and a conventional Cu-Cr alloy were compared in terms of workability when welding test pieces and contact shapes, which will be described later, were obtained by cutting. The chips of the Cu-Cr-Te alloy of the present invention are not continuous,
It formed into short scales and had very good workability.
If the processing time of the Cu-Cr-Te alloy of the present invention is 1, it is 1.5 to 1.6 times that of the conventional Cu-Cr alloy, and the wear rate of cutting tools is also lower than that of the conventional alloy.
The alloy of the present invention was about 30% lower. As mentioned above, it was confirmed that the contact material of the present invention has good machinability and excellent shapeability, but this is because most of the Te is in a granular state at the interface between Cu and Cr particles. This is due to the structure of the alloy present in the steel. Next, welding test pieces with a diameter of 15 mm, a height of 10 mm, and a tip diameter of 100R were taken from these alloys, and the welding force was measured using a welding tester. The test conditions were a contact force of 8 kg on the test piece, a degree of vacuum of 5 x 10 -4 torr, and a current applied.
After increasing the current in steps from 2kA to 1kA,
The welding force up to 10kA was measured, and the results are shown in Figure 1. FIG. 1 is a diagram showing the relationship between welding force and test current value, and the numbers shown in Table 1 correspond to the numbers assigned to each curve in FIG. 1. Conventional alloy No. 6 is also plotted in Figure 1, but the alloy of the present invention has no large difference in welding force, so No. 1 shows the maximum welding force at a test current of 10 kA.
We list only three curves, No. 4 showing the lowest welding force and No. 3 showing an intermediate value, and No. 2 and No. 5.
is omitted because the curves are confusing and difficult to distinguish. Figure 1 shows that the welding force of the alloy of the present invention is significantly lower than that of conventional alloys, and even if the contacts are welded, they open easily, whereas the conventional alloys weld more and more firmly as the current increases. Ori,
It can be seen from FIG. 1 that the alloy of the present invention has superior welding resistance. Next, the cutting current value was measured by installing it in a vacuum valve with a rating of 7.2 kV/8 kA, and the alloy of the present invention and the conventional alloy were compared. The contact dimensions are 25 mm outside diameter and 13 mm inside diameter.
Contact gap is 6mm, contact load is 20Kg, vacuum degree is
10 -6 torr and the test conditions are test voltage AC300V,
The break current was 30.5A peak, and the opening phase was 90°. Although the number of tests was 50 in each case, the results shown in Table 2 were obtained when the maximum, minimum, and average cutting current values were expressed. The numbers shown in Table 2 correspond to the numbers in Table 1. Second
〔発明の効果〕〔Effect of the invention〕
以上実施例で説明したように、Cr焼結体にCu
−Te合金を溶浸して製造する本発明に係る真空
しや断器用接点材料は従来のCu−Cr系合金にTe
を0.05〜４％添加し、合金中にTeを微細均一に
分散させCuを45〜60％の範囲に設定することに
より、導電率を損うことなく耐溶着性とさい断電
流特性を改善することができる。さらに、本発明
の接点材料は、機械加工性がよく切削時間の短縮
と切削工具の寿命の増大を図ることができる。
この結果本発明の合金を用いた真空しや断器は
さい断電流に起因する異常電圧の発生による機器
損傷を防ぐためのサージアブソーバの付設などを
必要とせず、また耐溶着性にすぐれることから操
作機などの小型軽量化も可能であり、Cu−Cr接
点の適用範囲の拡大とともに経済的効果も大き
い。
As explained in the examples above, Cu is added to the Cr sintered body.
-The contact material for vacuum shields and breakers according to the present invention, which is manufactured by infiltrating a Te alloy, is a Te alloy in the conventional Cu-Cr alloy.
By adding 0.05 to 4% of Te, finely and uniformly dispersing Te in the alloy, and setting Cu in the range of 45 to 60%, welding resistance and scissor current characteristics are improved without impairing conductivity. be able to. Furthermore, the contact material of the present invention has good machinability and can shorten cutting time and extend the life of cutting tools. As a result, the vacuum circuit breaker using the alloy of the present invention does not require the installation of a surge absorber to prevent damage to equipment due to the generation of abnormal voltage caused by the cutting current, and has excellent welding resistance. It is also possible to make operating devices smaller and lighter, expanding the scope of application of Cu-Cr contacts and having great economic effects.
【図面の簡単な説明】[Brief explanation of drawings]
第１図は本発明に係る接点材料の溶着力と電流
の関係を示す線図である。
FIG. 1 is a diagram showing the relationship between the welding force and current of the contact material according to the present invention.