【発明の詳細な説明】[Detailed description of the invention]
本発明は、ワイヤカツト放電加工に於て利用す
るワイヤ電極線に関する。
従来、耐熱性で抗張力の高い芯線に対して適正
形状の導電性金属（合金を含む）の被覆を密着
し、又は接着層間で拡散接着したワイヤカツト放
電加工用電極線について、提案されている。ワイ
ヤカツト放電加工用電極線は、導電性が良好で、
全体の引張り強度が高く、曲撓若しくは方向位角
がきびしいような導通路に用いられる場合が多
い。
このような利用をするために、抗張力の高い芯
線に良導電性材の表面被覆層を形成した複合線が
用いられるが、被覆層の形成と、その厚さ等の厚
薄と、密着性と全体強度は、時として相反する要
求をもたらし、時として合体強度を劣化させ、時
には芯線又被覆物組成の成分変更を必要とすると
きを生じる。又所要の形状が、ワイヤ使用の結果
として維持できないものになつたときの再成形性
を維持できるか否かも重要である。このような要
求を満たすために、例えば特公昭57−57211号の
ような有用なものが既に提案されている。これは
鉄を基礎成分とした芯線を用いるから張力を大と
することができ、ねじれ、振れが少なくなる。芯
線の周囲に導電性金属の被覆層を形成するから放
電加工のための通電性、放電特性が良好である。
又芯線の鋼線と被覆金属の銅等の結合力が強い
ため、加工中に被覆層が剥離することなく、安定
した放電加工を行なうことができる特徴を有す
る。
本発明は、抗張力の高い芯線に良導電性材を被
覆してなるこのような従来の電極線を改良して、
更に被覆層の密着力が強く、強度が高く、且つ加
工性能に於て優れたワイヤカツト放電加工用電極
線提供を目的とするものであり、鋼線を芯線と
し、該芯線に芯線よりも通電性良好な金属に重量
比で１〜10％の希土類元素を含ませた材料の被覆
層を形成するようにしたことを特徴とするもので
ある。
次に、本発明を一実施例について説明する。第
１図は本発明の一実施例ワイヤ電極の断面円形の
ものの一部拡大側断面図である。鋼製ワイヤ１
（炭素0.1％JIS−SWRMI）の外周にサマリウム
を５％（重量比）含ませた銅、又は銅合金の被覆
密着層２（以下、被覆密着層には良好な密着をす
るメツキによる形成層をも含んで呼ぶ。）を形成
し、更に該層２の外周にサマリウムを３％（重量
比）含ませた銅金（Cu−Zn，Cu−Sn，Cu−Al，
Cu−Sn−Zn，Cu−Sn−Ｐ，Cu−Al−Si等）の
密着被覆層３を形成した複層被覆層からなるワイ
ヤ電極１０を示す。
しかして、本発明により被覆層２に希土類元素
を適量含ませるようにすると、芯線１と被覆層２
との接合部の密着性が良くなり、密着力が増大す
ると共に、被覆層２の強度も増大して、全体とし
て抗張力、強度が増大し、被覆層２の硬度、強度
等をも高め、又放電加工性能向上に有効な易放電
性及び良好な放電発生点の分散性を有する電極線
とすることができるが、これは希土類元素を含ま
せたことによる次のような現象によるものと考え
られる。
即ち、本発明により被覆層２中に含ませた希土
類元素は、その一部が希土類元素のままで分散合
金化されているだけでなく、その分散合金化され
た希土類元素は殆んどその種類によらず、芯線及
び被覆層を構成する他の各金属元素等に対しより
高い活性度を有しているため、その一部以上のも
のが結晶中や粒界内に介在する酸素を取り込ん
で、易放電性の希土類元素酸化物を結晶中や粒界
内に均一に分散介在させて分散強化し、或いは更
に、製造、後処理、使用等の条件によつては、芯
線の表層部分及び被覆層を構成する他の金属の金
属酸化物を還元して前記易放電性の希土類元素酸
化物を結晶中や粒界内に生成分散介在させて接合
部を活性化及び分散強化し、又希土類元素は被覆
層を構成する金属、特に被覆層金属として常用の
銅と多くの化合物Ｒ・CUX（但し、Ｒ：希土類元
素、Ｘ＝１，２，３，……７）を殆んどどの希土
類元素の場合にもほぼ同じ比率で生成し、該化合
物は結晶中や粒界内に分散する。
そして、本発明のような、芯線と被覆層間の密
着性の如きものを考える場合の一つの指標とし
て、両者の元素間の化合物の生成エネルギを、該
エネルギが大きい程密着性が良い、又は強いとい
う合理的な理由がある故に、検討するに、銅系合
金からなる被覆層が希土類元素を含まない場合、
被覆層と芯線鋼（Fe−Si−Ｃ−他合金）との境
界に於ける化合物生成エネルギを調べると、
FeCu −△Ｈ＝10K cal／mol
SiCu2 −△Ｈ＝13K cal／mol
の如くであるが、上記被覆層に希土類元素を含ま
せた場合、更に希土類元素との化合物生成エネル
ギが加算されることになるが、その生成エネルギ
は次のように相当大きなものである。
CeFe −△Ｈ＝57.0K cal／mol
CeSi −△Ｈ＝73.5K cal／mol
DySi −△Ｈ＝63.0K cal／mol
ErSi −△Ｈ＝83.7K cal／mol
EuSi −△Ｈ＝62.5K cal／mol
従つて、芯線の鋼成分と銅系合金被覆層に含さ
せた希土類元素とは、強力に結合し合金化するた
め密着性が良好になるものである。又芯線として
の鋼線表面の酸化物が酸化被膜もその一部以上
が、前述したように銅系合金被覆層に含ませた希
土類元素により還元されて酸化物が生成される一
方で活性化され、鋼芯線と被覆層との密着性が良
好、強力なものとなる。酸化物生成エネルギの列
を挙げると下の如くである。
−△Ｈ〔Ｋ cal／mol〕−△Ｈ〔Ｋ cal／mol〕
FeO 63.2 Ce2O3 435.4
Fe2O3 −196.3 Er2O3 453.6
SiO2 −217.6 Eu2O3 412.4
Gd2O3 434.0
La2O3 428.6
CeAlO3 421.4
上記の芯線としての鋼線がアルミニウムを有効
成分として含有する鋼線（Fe−Si−Ｃ−Al）の
場合には、
FeAl −△Ｈ＝12.2 Ｋ cal／mol
Cu3Al2 −△Ｈ＝14.0 Ｋ cal／mol
これに更に希土類元素を含ませると化合物生成
エネルギは、例えば、
Ce3Al2 −△Ｈ＝42.0 Ｋ cal／mol
の如くであつて、密着性が向上するものである。
そして以上のような芯線１と被覆層２との間の
密着性の作用等は、被覆層２と被覆層３との密着
性の場合にも、ほぼ類似の作用等を適用推定可能
であつて、複層被覆層電極線の場合にも、その一
層又は各に希土類元素を含ませることにより、被
覆層と芯線間、或いは更に被覆層間の密着力が増
し、全体としてより抗張力、及び強度等を高めた
電極線とすることができるものである。
又、希土類元素は、上述の如く高活性元素であ
つて、又、生成により分散介在することになる希
土類元素酸化物は、何れもその仕事函数が約２〜
3eVの範囲にあつて、トリウム酸化物（ThO2）
に次ぐ程度に低く、易電子放射性である所から易
放電性であり、これが被覆層の主に表面部に分散
して存在することにより希土類元素の含有部位で
効率良く放電が発生し、加工速度が向上する。
又、放電の発生し易い希土類元素及びその酸化
物や前述銅化合物等の化合物が被覆層に分散して
含有されることにより、放電の分散性が良くな
り、集中放電が起き難くくなるため集中放電によ
る電極線の断線を防止することができる。
最終仕上り寸が直径200ミクロンの前記のワイ
ヤ電極１０において、前記の銅層２の厚さ（片
側）ｔ４と、銅合金層３の厚さ（片側）ｔ３と、
銅層プラス銅合金層の厚さ（片側）ｔ２とから積
層したワイヤ電極に於て、厚さｔ２とワイヤ１０
の引張り強度と抵抗及び夫々の場合の加工速度の
関係を第１表に示した。
加工速度は、最大196mm2／minで、ワークの材
質SKD１１を加工し、平均的には130mm2／minで
加工した。
The present invention relates to a wire electrode wire used in wire cut electrical discharge machining. Conventionally, proposals have been made for wire-cut electrode wires for electrical discharge machining, in which a conductive metal (including alloy) coating of an appropriate shape is closely adhered to a heat-resistant, high-tensile core wire, or diffusion bonded between adhesive layers. Wire cut electrode wire for electrical discharge machining has good conductivity.
It has a high overall tensile strength and is often used for conductive paths with severe bending or orientation. For such uses, composite wires are used, in which a surface coating layer of a highly conductive material is formed on a core wire with high tensile strength, but the formation of the coating layer, its thickness, adhesion, and overall Strength sometimes results in conflicting requirements, sometimes resulting in deterioration of the composite strength, and sometimes requiring changes in the core wire or coating composition. It is also important to maintain remouldability when the desired shape becomes unsustainable as a result of wire use. In order to meet such requirements, useful devices such as Japanese Patent Publication No. 57-57211 have already been proposed. Since this uses a core wire with iron as its basic component, the tension can be increased and twisting and wobbling are reduced. Since a conductive metal coating layer is formed around the core wire, it has good electrical conductivity and discharge characteristics for electrical discharge machining. Furthermore, since the bond between the core steel wire and the coating metal, such as copper, is strong, the coating layer does not peel off during machining, and stable electrical discharge machining can be performed. The present invention improves such a conventional electrode wire in which a core wire with high tensile strength is coated with a highly conductive material.
Furthermore, the purpose is to provide a wire cut electrode wire for electric discharge machining that has strong adhesion of the coating layer, high strength, and excellent machining performance. It is characterized in that a coating layer is formed of a material containing a rare earth element in a weight ratio of 1 to 10% in a good metal. Next, one embodiment of the present invention will be described. FIG. 1 is a partially enlarged side sectional view of a wire electrode having a circular cross section according to an embodiment of the present invention. steel wire 1
Coating adhesion layer 2 of copper or copper alloy containing 5% samarium (by weight) on the outer periphery of (carbon 0.1% JIS-SWRMI) (hereinafter, the coating adhesion layer is a layer formed by plating that provides good adhesion. copper-gold (Cu-Zn, Cu-Sn, Cu-Al,
1 shows a wire electrode 10 made of a multilayer coating layer on which an adhesive coating layer 3 of Cu-Sn-Zn, Cu-Sn-P, Cu-Al-Si, etc.) is formed. According to the present invention, when the coating layer 2 contains an appropriate amount of rare earth elements, the core wire 1 and the coating layer 2
The adhesion of the joint with the coating layer 2 is improved, the adhesion is increased, and the strength of the coating layer 2 is also increased, the tensile strength and strength of the coating layer 2 are increased as a whole, and the hardness and strength of the coating layer 2 are also increased. It is possible to obtain an electrode wire that has easy discharge properties and good dispersion of discharge points, which are effective in improving electrical discharge machining performance, and this is thought to be due to the following phenomenon caused by the inclusion of rare earth elements. . That is, the rare earth element contained in the coating layer 2 according to the present invention is not only partially alloyed as a rare earth element, but also almost all of the rare earth elements that have been dispersed alloyed are of the same type. However, it has a higher activity than other metal elements constituting the core wire and coating layer, so some or more of them may take in oxygen present in the crystals or grain boundaries. , Dispersion strengthening is achieved by uniformly dispersing easily dischargeable rare earth element oxides in the crystals and grain boundaries, or depending on the conditions of manufacturing, post-treatment, use, etc., the surface layer of the core wire and the coating. The metal oxides of other metals constituting the layer are reduced to generate and disperse the easily dischargeable rare earth element oxides in the crystals and grain boundaries, thereby activating and dispersing and strengthening the joints. is the metal constituting the coating layer, especially copper, which is commonly used as the coating layer metal, and many compounds R・C UX (where R: rare earth element, In the case of elements, they are produced in approximately the same ratio, and the compounds are dispersed in crystals and grain boundaries. When considering the adhesion between the core wire and the coating layer, as in the present invention, the energy for forming a compound between the two elements is used as an indicator. For this reason, we will consider that if the coating layer made of copper-based alloy does not contain rare earth elements,
Examining the energy of compound formation at the boundary between the coating layer and the core steel (Fe-Si-C-other alloy), it is as follows: FeCu −△H=10K cal/mol SiCu 2 −△H=13K cal/mol However, when the above-mentioned coating layer contains a rare earth element, the energy for forming a compound with the rare earth element is further added, and the energy for forming the compound is considerably large as shown below. CeFe −△H=57.0K cal/mol CeSi −△H=73.5K cal/mol DySi −△H=63.0K cal/mol ErSi −△H=83.7K cal/mol EuSi −△H=62.5K cal/mol Therefore, the steel component of the core wire and the rare earth element contained in the copper-based alloy coating layer are strongly bonded and alloyed, resulting in good adhesion. In addition, at least a part of the oxide film on the surface of the steel wire used as the core wire is reduced by the rare earth element contained in the copper-based alloy coating layer as described above, and oxides are generated while being activated. , the adhesion between the steel core wire and the coating layer is good and strong. The sequence of oxide production energies is as follows. −△H [K cal/mol] −△H [K cal/mol] FeO 63.2 Ce 2 O 3 435.4 Fe 2 O 3 −196.3 Er 2 O 3 453.6 SiO 2 −217.6 Eu 2 O 3 412.4 Gd 2 O 3 434.0 La 2 O 3 428.6 CeAlO 3 421.4 If the above steel wire as the core wire is a steel wire containing aluminum as an active ingredient (Fe-Si-C-Al), FeAl −△H=12.2 K cal/mol Cu 3 Al 2 −△H = 14.0 K cal/mol If a rare earth element is further included in this, the compound formation energy is, for example, Ce 3 Al 2 −△H = 42.0 K cal/mol, and the adhesion is It will improve. The effects of the adhesion between the core wire 1 and the coating layer 2 as described above can be estimated by applying almost similar effects to the adhesion between the coating layers 2 and 3. In the case of a multi-layer coated electrode wire, by including a rare earth element in one layer or each layer, the adhesion between the coating layer and the core wire, or even between the coating layers, is increased, and the overall tensile strength and strength etc. are increased. This can be used as a raised electrode wire. Furthermore, as mentioned above, rare earth elements are highly active elements, and the rare earth element oxides that become dispersed as a result of their formation have work functions of approximately 2 to 2.
In the 3eV range, thorium oxide (ThO 2 )
It is easily dischargeable because it is electron emissive, and because it is dispersed mainly on the surface of the coating layer, electric discharge occurs efficiently in the rare earth element-containing parts, which increases the machining speed. will improve. In addition, by dispersing and containing rare earth elements and their oxides, and compounds such as the aforementioned copper compounds, which are likely to cause discharge, in the coating layer, the dispersibility of discharge becomes better and concentrated discharge becomes less likely to occur. Breakage of the electrode wire due to discharge can be prevented. In the wire electrode 10 with a final finished size of 200 micrometers in diameter, the thickness of the copper layer 2 (on one side) t4, the thickness of the copper alloy layer 3 (on one side) t3,
In the wire electrode laminated from the copper layer plus the copper alloy layer thickness (one side) t2, the thickness t2 and the wire 10
Table 1 shows the relationship between the tensile strength and resistance and the processing speed in each case. The machining speed was a maximum of 196 mm 2 /min for the workpiece material SKD11, and the average speed was 130 mm 2 /min.
【表】
ヤを示す。
第１表に示す実験結果から、鋼線に被覆層を形
成する場合は、鋼芯を有さないCu−Zn合金のみ
からなるワイヤと比較して、被覆層の厚さｔ２を
30〜50ミクロン（電極線全体の径の約18〜29％に
相当）としたときに同程度の加工速度が得られ、
このとき抗張力が２倍以上になることが分る。
次に、0.18mmφの鋼線に銅を10μm厚に直流電
流密度5A／ｄm2で電気メツキした銅被覆鋼線を
用いる特公昭57−57211号公報記載のものとの比
較例を挙げると、直流電流密度5A／ｄm2の電気
メツキ条件で、２％Sm−残部Cuメツキして本発
明の0.19mmφワイヤ電極を製作し、上記公報記載
の加工条件、板厚45mmのSKD１１材をワイヤ電
極更新送り速度1m／min、付与張力2000grとし
たときの加工速度、及びワイヤ電極の特性は夫々
次の通りであつた。[Table] Shows y.
From the experimental results shown in Table 1, when forming a coating layer on a steel wire, the thickness t2 of the coating layer is
A similar processing speed can be obtained when the diameter is 30 to 50 microns (corresponding to about 18 to 29% of the entire electrode wire diameter).
It can be seen that the tensile strength is more than doubled at this time. Next, we will give a comparison example with the one described in Japanese Patent Publication No. 57-57211, which uses a 0.18 mmφ steel wire electroplated with copper to a thickness of 10 μm at a DC current density of 5 A/dm 2 . A 0.19 mmφ wire electrode of the present invention was produced by electroplating with 2% Sm and the remainder Cu under the electroplating conditions of a current density of 5 A/dm 2 , and the wire electrode renewal feed of SKD11 material with a plate thickness of 45 mm was carried out under the processing conditions described in the above publication. The processing speed at a speed of 1 m/min and applied tension of 2000 gr and the characteristics of the wire electrode were as follows.
【表】
又、上述の実験に於て、被覆層形成の電気メツ
キ条件を5A／ｄm2、τon：2μs，τoff：6μsのパル
ス通電メツキとし、夫々6μmの被覆を形成したワ
イヤ電極を用いた場合の夫々の結果は次の通りで
あつた。尚、加工する被加工体の板厚及びワイヤ
電極への付与張力は前述の実験と同一とし、ワイ
ヤ電極の更新送り速度は0.3m／minとした。[Table] In addition, in the above experiment, the electroplating conditions for forming the coating layer were pulse current plating of 5A/dm 2 , τon: 2μs, τoff: 6μs, and wire electrodes with a coating of 6μm were used. The results for each case were as follows. The thickness of the workpiece to be machined and the tension applied to the wire electrode were the same as in the previous experiment, and the renewal feed rate of the wire electrode was 0.3 m/min.
【表】
以上鋼線を芯線とする被覆層の場合も、被覆中
に希土類金属を含ませた本発明のものが何れも優
れていた。
このように本発明によれば、ワイヤ電極線が鋼
芯線と希土類元素を含む銅、黄銅等の被覆層が強
く結合して抗張力、強度を増大し、強い張力をか
けて加工するこができ、ねじれ、振動等を減少し
て安定加工でき、加工精度を向上することができ
る。
又、易放電性物質である希土類元素が被覆層に
分散して含有されることにより、能率良く加工が
行なわれて加工速度が向上すると共に、集中放電
による電極線の断線を防止し得る効果がある。
又、被覆層は芯線に強く接合し剥離することが
なく、又被覆層自体、希土類元素の含有によつて
強度が高まりガイドによる変形等もなく安定した
加工ができる。又活性度の高い希土類元素の含有
によつてより厚い被覆層が形成でき、層上に他の
材質の層を積層形成でき、且つ層間は強く結合す
る。厚い被覆の形成によつて精度が低下する場
合、異形外形とする場合等には被覆層形成後に線
引加工して精度を出すことが行なえる。
尚、芯線には、炭素含有量を多くした鋼線、ク
ロム系の鋼線、ステンレス鋼線その他の鉄を基礎
成分とした抗張力が大で曲撓性のある鋼線を、前
実施例の鋼線に代えて用い、同様の効果が得られ
た。被覆層も、銅以外の、例えば銅合金、亜鉛、
銀、ニツケル、アルミニウム系金属のような芯線
よりも良導電性の金属を、同様に用い得ることが
判明した。又含有させる希土類元素はイツトリウ
ムを含む殆んどすべてのランタニド元素を殆んど
区別なく用いることができ、元素のままで混合す
ることにより、被覆層中やその表層で酸化物やそ
の他の金属との化合物を形成する等して芯線表面
を活性化し、且つ被覆層を活性化して強い結合、
層の強度を高めるが、一部を予め酸化物として混
合しても有効である。混合量は前記実施例のよう
に重量比で５〜10％程度以下でよく少なくとも１
％程度以上加えないと有効でない。
又、希土類元素の含有量が10％を越えると電極
線の曲撓性が劣化し、ワイヤ電極の走行系に於け
る円滑な更新送りに支障を来すため、10％以下の
含有量とすることが望ましい。
又、芯線への良導電性金属の被覆には電着以外
に、化学メツキ、どぶ漬け等の従来の被覆電極に
利用されている被覆方法、手段が利用できる。被
覆層形成後熱処理して安定化させることもよい。
そして芯線、又は被覆形成された電極線の外形形
は丸線に限らず、帯線、角線、その他が適宜利用
できる。
既に述べた通り、本発明の電極線を用いた放電
芯線に於ては、在来の電極線を用いた場合に比
し、よく成果を上げ、良好な精度を得られるこ
と、コストダウンに寄与すること、芯線の表面に
薄い導電性金属被覆を用いるという技術思想は応
用分野が更に拡大されることを期待できる。[Table] In the case of the above-mentioned coating layers having a steel wire as the core wire, the coatings of the present invention containing rare earth metals in the coating were all excellent. As described above, according to the present invention, the wire electrode wire is strongly bonded to the steel core wire and the coating layer of copper, brass, etc. containing rare earth elements, increasing tensile strength and strength, and can be processed by applying strong tension. Stable machining can be achieved by reducing torsion, vibration, etc., and machining accuracy can be improved. In addition, by dispersing and containing rare earth elements, which are easily dischargeable substances, in the coating layer, machining can be carried out efficiently and the machining speed can be increased, as well as being effective in preventing disconnection of the electrode wire due to concentrated discharge. be. In addition, the coating layer is strongly bonded to the core wire and does not peel off, and the coating layer itself has increased strength due to the inclusion of rare earth elements, allowing stable processing without deformation due to guides. Furthermore, by containing a highly active rare earth element, a thicker coating layer can be formed, layers of other materials can be laminated on top of the layer, and the layers are strongly bonded. In cases where the accuracy is lowered due to the formation of a thick coating, or when an irregular outer shape is to be formed, etc., the accuracy can be increased by wire drawing after the coating layer is formed. The core wire may be a steel wire with a high carbon content, a chromium-based steel wire, a stainless steel wire, or other steel wire that has iron as its basic component and has high tensile strength and flexibility. A similar effect was obtained when used in place of the wire. The coating layer is also made of materials other than copper, such as copper alloy, zinc,
It has been found that metals with better conductivity than the core wire, such as silver, nickel, or aluminum based metals, can be used as well. In addition, almost all lanthanide elements including yttrium can be used without discrimination as rare earth elements, and by mixing the elements as they are, they can be mixed with oxides and other metals in the coating layer and its surface layer. Activate the core wire surface by forming a compound, and activate the coating layer to form a strong bond.
Although it increases the strength of the layer, it is also effective to mix some of it as an oxide in advance. The mixing amount may be about 5 to 10% by weight or less, as in the above embodiment, and at least 1%.
It is not effective unless you add about % or more. In addition, if the content of rare earth elements exceeds 10%, the flexibility of the electrode wire will deteriorate and this will hinder smooth renewal of the wire electrode running system, so the content should be 10% or less. This is desirable. In addition to electrodeposition, coating methods and means used for conventional coated electrodes, such as chemical plating and doweling, can be used to coat the core wire with a highly conductive metal. After forming the coating layer, it may be stabilized by heat treatment.
The outer shape of the core wire or the covered electrode wire is not limited to a round wire, but a band wire, a square wire, and others may be used as appropriate. As already mentioned, in the discharge core wire using the electrode wire of the present invention, compared to the case of using the conventional electrode wire, the results are better, good accuracy can be obtained, and it contributes to cost reduction. The technical idea of using a thin conductive metal coating on the surface of the core wire can be expected to further expand its application fields.
【図面の簡単な説明】[Brief explanation of drawings]
第１図は本発明の一実施例の側断面拡大図であ
る。
１……芯線、２……銅被覆層、３……銅合金被
覆層、１０……電極ワイヤ、ｔ……電極ワイヤ直
径、ｔ１……鉄（芯）ワイヤの直径、ｔ２……銅
と銅合金の被覆の片側厚さ、ｔ３……銅合金被覆
の片側厚さ。
FIG. 1 is an enlarged side sectional view of one embodiment of the present invention. 1... Core wire, 2... Copper coating layer, 3... Copper alloy coating layer, 10... Electrode wire, t... Electrode wire diameter, t1... Diameter of iron (core) wire, t2... Copper and copper Thickness on one side of alloy coating, t3...Thickness on one side of copper alloy coating.