【発明の詳細な説明】[Detailed description of the invention]
本発明は超電導撚線上に高純アルミニウムを押
出被覆したアルミニウム安定化超電導導体の製造
方法に関するものである。
一般に超電導導体の安定化材には、銅又はアル
ミニウムが用いられているが、銅よりアルミニウ
ムの方が極低温における残留抵抗及び磁気抵抗が
小さいところから、最近ではアルミニウム安定化
超電導導体が多用されるようになり、いくつかの
製造方法が提案されている。これ等の方法は何れ
も導体表面を通常の研磨紙又は研磨ブラシにより
研磨してから導体上にアルミニウムを押出被覆す
るものである。しかるに超電導線を複数本撚り合
せた超電導撚線については、例えば第１図に示す
ように撚線１表面を通常の一次枝毛４ａを有する
研磨ブラシ４により研磨しても、導線２間の谷間
３を研磨することができないため、超電導撚線と
押出被覆したアルミニウムとの接合が不十分とな
り、アルミニウム安定化超電導導体としての特性
が不十分となる欠点があつた。
このため超電導撚線は可撓性が優れているにも
かかわらず、押出被覆によるアルミニウム安定化
超電導導体には用いられず、主に芯線となる超電
導導体又は複数の超電導線を純銅中に内蔵させた
単一の超電導導体上にアルミニウムを押出被覆し
ている。
本発明はこれに鑑み可撓性の優れたアルミニウ
ム安定化超電導導体を得る目的で種々検討の結
果、二次以上の枝毛を有する研磨ブラシで研磨す
ることにより、超電導撚線の導線間の谷間まで研
磨することができることを知見し、撚線上に接合
性の優れた高純アルミニウムを押出被覆したアル
ミニウム安定化超電導導体の製造方法を開発した
もので、超電導線又は表面に銅系部材を被覆した
超電導線を複数本撚り合せ、該撚線表面を二次以
上の枝毛を有する研磨ブラシにより研磨してから
脱脂洗浄し、これを非酸化性雰囲気中に保持して
撚線上に高純アルミニウムを押出被覆することを
特徴とするものである。
即ち本発明は、超電導線、表面に純銅を被覆し
た超電導線又は表面に銅合金を被覆した超電導線
を複数本撚り合せて超電導撚線を形成し、該撚線
表面を第２図に示すように一次枝毛５ａに更に二
次以上の枝毛５ｂを有する研磨ブラシ５で研磨す
ることにより、導線２間の谷間３まで研磨する。
この研磨により撚線１表面の酸化皮膜を除去し、
続いて脱脂洗浄して非酸化性雰囲気に保持し、撚
線上に高純アルミニウムを押出被覆するものであ
る。
撚線を研磨、脱脂洗浄後、非酸化性雰囲気中に
保持するのは、撚線上に高純アルミニウムを押出
被覆するまで、活性な撚線表面を保持するためで
ある。また高純アルミニウムの押出被覆は、第３
図に示すように左右にラム６ａ，６ｂを設けた加
圧室７ａ，７ｂを有し、その一方の側壁８ａ中央
にニツプル９を、他方の側壁８ｂ中央にダイス１
０を取付けた押出機を用い、加圧室７ａ，７ｂ内
に高純アルミニウムビレツト１１ａ，１１ｂを装
入し、ニツプル９を通して押出機内に超電導撚線
１を挿入してダイス１０より出る撚線１の周面
に、ビレツト１１ａ，１１ｂをラム６ａ，６ｂに
より加圧して高純アルミニウムを押出せばよい。
以下本発明を実施例について詳細に説明する。
NbTiからなる直径７μの超電導線を400本内蔵さ
せた純銅線に、Cu−Ni合金を被覆した直径0.66
mmの素線10本を中空状に撚り合せ、これを扁平状
に加圧成形した超電導撚線を用い、その周面に第
３図に示す押出機により純度99.999％の高純Alを
押出し、第４図に示すように素線２ａを撚り合せ
て扁平状とした撚線１ａ周面に高純Al１２を被
覆し、巾８mm、厚さ４mmのアルミニウム安定化超
電導導体を製造した。尚素線１本当りの占積率は
Cu33％、Cu−Ni合金34％、NbTi33％であつた。
高純Alの押出被覆に際しては、超電導撚線の
表面を第１表に示す手段により研磨してから脱脂
洗浄し、これをアルゴンガス雰囲気中に保持し、
第３図に示す押出機内にニツプルを通して挿入
し、ダイスから出る撚線周面に400℃に加熱した
高純Alを押出被覆した。
このようにして製造したアルミニウム安定化超
電導導体について、アルミニウムと超電導撚線の
密着性を評価するため、半径４mmの曲面を有する
金具に挾み、フラツトワイズに90゜曲げを繰返
し、アルミニウムと超電導撚線の界面が剥離する
までの曲げ回数を求めた。その結果を第１表に併
記した。尚曲げ回数は90゜曲げて１回、元に戻し
て２回、反対方向に90゜曲げて３回、元に戻して
４回というようにして求めた。
The present invention relates to a method for producing an aluminum-stabilized superconducting conductor in which superconducting strands are coated with high-purity aluminum by extrusion. Copper or aluminum is generally used as a stabilizing material for superconducting conductors, but recently aluminum-stabilized superconducting conductors are often used because aluminum has lower residual resistance and magnetic resistance at extremely low temperatures than copper. Several manufacturing methods have been proposed. In all of these methods, the conductor surface is polished with ordinary abrasive paper or an abrasive brush, and then aluminum is coated on the conductor by extrusion. However, for a superconducting stranded wire made by twisting a plurality of superconducting wires, even if the surface of the stranded wire 1 is polished with a polishing brush 4 having ordinary primary split ends 4a as shown in FIG. 3 cannot be polished, the bond between the superconducting stranded wire and the extrusion-coated aluminum becomes insufficient, resulting in insufficient properties as an aluminum-stabilized superconducting conductor. For this reason, although superconducting stranded wires have excellent flexibility, they are not used in extrusion-coated aluminum stabilized superconducting conductors, and are mainly made by incorporating a core superconducting conductor or multiple superconducting wires in pure copper. Aluminum is extruded onto a single superconducting conductor. In view of this, the present invention has been developed as a result of various studies for the purpose of obtaining an aluminum-stabilized superconducting conductor with excellent flexibility. By polishing with a polishing brush having secondary or higher branch ends, the valleys between conductive wires of stranded superconducting wires can be removed. We developed a method for manufacturing aluminum stabilized superconducting conductors in which stranded wires are extruded and coated with high-purity aluminum with excellent bonding properties. A plurality of superconducting wires are twisted together, the surface of the stranded wires is polished with an abrasive brush having secondary or higher-order split ends, and then degreased and cleaned.The strands are held in a non-oxidizing atmosphere and high-purity aluminum is coated on the stranded wires. It is characterized by extrusion coating. That is, in the present invention, a plurality of superconducting wires, superconducting wires whose surfaces are coated with pure copper, or superconducting wires whose surfaces are coated with copper alloy are twisted together to form a superconducting stranded wire, and the surface of the stranded wire is formed as shown in FIG. By polishing the primary split ends 5a with a polishing brush 5 having secondary or higher-order split ends 5b, the valleys 3 between the conducting wires 2 are polished.
This polishing removes the oxide film on the surface of the stranded wire 1,
Subsequently, the strands are degreased and cleaned, kept in a non-oxidizing atmosphere, and high-purity aluminum is extruded and coated on the stranded wires. The reason why the stranded wire is kept in a non-oxidizing atmosphere after polishing, degreasing and cleaning is to maintain the active stranded wire surface until the stranded wire is extruded and coated with high purity aluminum. In addition, the extrusion coating of high-purity aluminum
As shown in the figure, it has pressurizing chambers 7a and 7b provided with rams 6a and 6b on the left and right, and a nipple 9 is placed in the center of one side wall 8a, and a die 1 is placed in the center of the other side wall 8b.
Using an extruder equipped with 0, high-purity aluminum billets 11a and 11b are charged into pressurizing chambers 7a and 7b, and superconducting stranded wire 1 is inserted into the extruder through nipple 9, and the stranded wire exits from die 10. Billets 11a and 11b are pressurized by rams 6a and 6b to extrude high-purity aluminum onto the circumferential surface of aluminum plate 1. The present invention will be described in detail below with reference to examples.
A pure copper wire with a diameter of 0.66 mm coated with a Cu-Ni alloy is built into a pure copper wire containing 400 NbTi superconducting wires with a diameter of 7 μm.
A superconducting stranded wire is made by twisting 10 strands of mm wire into a hollow shape and press-molding it into a flat shape, and extruding high-purity Al with a purity of 99.999% on the circumferential surface of the wire using an extruder shown in Figure 3. As shown in FIG. 4, the strands 2a were twisted together to form a flat stranded wire 1a, and the circumferential surface of the stranded wire 1a was coated with high-purity Al12 to produce an aluminum-stabilized superconducting conductor having a width of 8 mm and a thickness of 4 mm. The space factor for one bare wire is
The contents were 33% Cu, 34% Cu-Ni alloy, and 33% NbTi. When extrusion coating high-purity Al, the surface of the superconducting stranded wire is polished by the means shown in Table 1, degreased and cleaned, and held in an argon gas atmosphere.
The wire was inserted through a nipple into the extruder shown in FIG. 3, and high-purity Al heated to 400° C. was coated by extrusion on the circumferential surface of the stranded wire coming out of the die. In order to evaluate the adhesion between aluminum and the superconducting strands, the aluminum stabilized superconducting conductor produced in this way was held between metal fittings with a curved surface of 4 mm in radius and repeatedly bent 90° flatwise. The number of bending cycles until the interface peeled off was determined. The results are also listed in Table 1. The number of bending times was determined by bending 90 degrees once, returning to the original position twice, bending 90 degrees in the opposite direction three times, and returning to the original position four times.
【表】
磨紙等を押し当てた。
第１表から明らかなように本発明方法によるも
のは、比較方法と比べてアルミニウムと超電導撚
線の界面が剥離するまでの回数がはるかに高く、
十分な接合強度を有しており、従来困難とされて
いた超電導撚線上にアルミニウムの押出被覆を可
能にし、可撓性の良好なアルミニウム安定化超電
導導体を製造することができるもので、工業上顕
著な効果を奏するものである。[Front] A polishing paper, etc. was pressed against the surface.
As is clear from Table 1, the number of times it takes for the interface between aluminum and superconducting strands to separate is much higher in the method of the present invention than in the comparative method.
It has sufficient bonding strength and makes it possible to extrude aluminum on superconducting stranded wires, which was previously considered difficult, and to produce aluminum-stabilized superconducting conductors with good flexibility. This has a remarkable effect.
【図面の簡単な説明】[Brief explanation of the drawing]
第１図は従来の一次枝毛ブラシによる研磨状態
を示す説明図、第２図は本発明における二次以上
の枝毛ブラシによる研磨状態を示す説明図。第３
図はアルミニウムの押出被覆装置の一例を示す側
断面図、第４図はアルミニウム安定化超電導導体
の一例を示す断面図である。
１，１ａ……超電導撚線、２，２ａ……超電導
線（素線）、４……一次枝毛研磨ブラシ、５……
二次枝毛研磨ブラシ、６ａ，６ｂ……ラム、７
ａ，７ｂ……加圧室、８ａ，８ｂ……側壁、９…
…ニツプル、１０……ダイス。
FIG. 1 is an explanatory diagram showing a polishing state using a conventional primary split-end brush, and FIG. 2 is an explanatory diagram showing a polishing state using a secondary or higher-order split end brush according to the present invention. Third
The figure is a side sectional view showing an example of an aluminum extrusion coating apparatus, and FIG. 4 is a sectional view showing an example of an aluminum stabilized superconducting conductor. 1, 1a... Superconducting stranded wire, 2, 2a... Superconducting wire (strand), 4... Primary split end polishing brush, 5...
Secondary split end polishing brush, 6a, 6b... Ram, 7
a, 7b...pressure chamber, 8a, 8b...side wall, 9...
...Nitspur, 10...Dice.