【発明の詳細な説明】[Detailed description of the invention]
本発明は、放電加工用電極の改良に関する。
一般にダイヤモンドダイスの穴明け加工を行な
うには、第１図に示す如く先端部１ａを10度の角
度で尖鋭に研摩成形した白金族又は白金族合金よ
り成る放電加工用電極１を電解液（硝酸カリウム
10％）２中に４mm程度浸漬し、電解液２中に於い
て放電加工用電極１の下方にセツトしたダイヤモ
ンド３を回転せしめながら、放電加工用電極１か
ら放電してダイヤモンド３にダイス穴３ａを穴明
け加工している。
ところでこのダイヤモンドダイスの放電加工
時、酸素，水素（ガス）泡の発生により、電解液
２放電加工用電極１との間に僅かな間隙が生じ、
液面下で放電が起る。特に液表面付近にある電極
の部分（以下、「電解液境界部」という。）は穴明
け加工に寄与しない放電が激しく、第２図に示す
如く放電加工用電極１の電解液境界部１ｂの局部
的消耗が著しく、第３図に示す如く電解液境界部
１ｂがやせ細つて折損してしまう。この為点線の
如く研摩して再使用しているが、先端部１ａが無
駄となるので、放電加工用電極１の使用回数が少
なく、歩留が悪いものである。
本発明はかかる問題点を解決すべくなされたも
のであり、放電加工中電解液境界部が決して消耗
することのない放電加工用電極を提供せんとする
ものである。
本発明の放電加工用電極はダイヤモンドを回転
させながら電極から電解液に放電するダイヤモン
ド穴明け加工用の、白金族金属又は白金族合金の
放電加工用電極において、該電極の電解液境界部
を絶縁体により被覆し、先端部を尖鋭に研摩成形
したことを特徴とするものである。
かかる本発明の放電加工用電極１′は、第４図
に示す如く電解液（硝酸カリウム10％）２中に４
mm程度浸漬し、電解液２中に於いて放電加工用電
極１′の下方に予めセツトしたダイヤモンド３を
回転せしめながら、放電加工用電極１′から放電
してダイヤモンド３にダイス穴３ａを穴明け加工
すると、酸素，水素（ガス）泡の発生により、電
解液２と放電加工用電極１′との間に僅かな間隙
が生じ、液面下で放電が起るが、放電加工用電極
１′の電解液境界部１ｂがセラミツク４に被われ
ているのでこの部分から放電は起らず、従つて電
解液境界部１ｂは消耗せず、先端部１ａのみ第５
図に示す如く消耗していき、やがて第６図に示す
如く先端部１ａがやせ細つたならば点線の如く研
摩成形して再使用する。
尚、第４図に示す本発明の放電加工用電極１′
は、尖鋭な先端部１ａにのみセラミツク４を有し
ないが、セラミツク４は放電の激しい電解液表面
付近にありさえすれば良いもので、電解液境界部
１ｂの下方の円柱部１ｃもダイヤモンド３のダイ
ス穴３ａの穴明け加工に使用される場合は、第７
図に示す如く円柱部１ｃのセラミツクは無くとも
良いものである。この放電加工用電極１″は使用
により第８図に示すやせ細つた場合第６図に示す
点線の如く研摩成形して再使用する。
次に本発明による放電加工用電極の効果を明瞭
ならしめる為にその具体的な実施例と従来例によ
るダイヤモンドダイスの穴明け加工について説明
する。
第４図に示す如く白金―イリジウム33w／ｏ合
金より成る直径0.5mm，長さ50mmの放電加工用電
極１の表面にセラミツク４を0.1mm被覆し、先端
部１ａを10度の角度で尖鋭に研摩成形して成る本
発明の放電加工用電極１′と、第１図に示す如く
白金―イリジウム３３ｗ／ｏ合金より成る直径
0.5mm，長さ50mmで先端部１ａを10度の角度で尖
鋭に研摩成形した従来の放電加工用電極１とによ
り、夫々ダイヤモンドに直径0.03mm，深さ0.3mm
のダイス穴の穴明け加工を行なつて電極の消耗度
合を測定したところ、下記の表に示すような結果
を得た。
The present invention relates to improvements in electrodes for electric discharge machining. Generally, in order to drill holes with a diamond die, an electrode 1 for electrical discharge machining made of a platinum group metal or a platinum group alloy whose tip 1a is sharply ground at an angle of 10 degrees as shown in FIG.
10%) 2, and while rotating the diamond 3 set below the electrical discharge machining electrode 1 in the electrolytic solution 2, a discharge is generated from the electrical discharge machining electrode 1 to form a die hole 3a in the diamond 3. is being drilled. By the way, during electrical discharge machining of this diamond die, due to the generation of oxygen and hydrogen (gas) bubbles, a slight gap is created between the electrolytic solution 2 and the electrical discharge machining electrode 1.
Electric discharge occurs below the liquid surface. Particularly in the part of the electrode near the liquid surface (hereinafter referred to as the "electrolyte boundary part"), the electric discharge that does not contribute to drilling is intense, and as shown in FIG. The local consumption is significant, and the electrolyte boundary portion 1b becomes thin and broken as shown in FIG. For this reason, although it is polished and reused as shown by the dotted line, the tip portion 1a is wasted, so the number of times the electric discharge machining electrode 1 is used is small, resulting in poor yield. The present invention has been made to solve these problems, and aims to provide an electrode for electric discharge machining in which the electrolyte boundary part is never consumed during electric discharge machining. The electrode for electric discharge machining of the present invention is an electrode for electric discharge machining of platinum group metals or platinum group alloys, which is used for diamond drilling in which electric discharge is discharged from the electrode into an electrolyte while rotating the diamond. It is characterized by being covered with a body and having a sharply polished tip. Such an electrode 1' for electric discharge machining of the present invention is made by dissolving 4 in an electrolytic solution (potassium nitrate 10%) 2 as shown in FIG.
3 mm, and while rotating the diamond 3 which had been set in advance below the electrical discharge machining electrode 1' in the electrolytic solution 2, a die hole 3a was made in the diamond 3 by discharging from the electrical discharge machining electrode 1'. During machining, due to the generation of oxygen and hydrogen (gas) bubbles, a slight gap is created between the electrolytic solution 2 and the electrical discharge machining electrode 1', and electrical discharge occurs below the liquid surface, but the electrical discharge machining electrode 1' Since the electrolyte boundary part 1b is covered with the ceramic 4, no discharge occurs from this part, and therefore the electrolyte boundary part 1b is not consumed, and only the tip part 1a is
It wears out as shown in the figure, and when the tip 1a becomes thin as shown in FIG. 6, it is polished and formed as shown by the dotted line and reused. Incidentally, the electric discharge machining electrode 1' of the present invention shown in FIG.
does not have the ceramic 4 only at the sharp tip 1a, but the ceramic 4 only needs to be near the surface of the electrolyte where the discharge is intense, and the cylindrical part 1c below the electrolyte boundary 1b also has diamonds 3. When used for drilling the die hole 3a, the seventh
As shown in the figure, the ceramic of the cylindrical portion 1c is not necessary. When this electric discharge machining electrode 1'' becomes thin due to use as shown in FIG. 8, it is reused after being polished and molded as shown by the dotted line in FIG. 6.Next, the effect of the electric discharge machining electrode according to the present invention will be clarified. For this purpose, we will explain the drilling process using a diamond die according to a specific example and a conventional example.As shown in Fig. 4, an electric discharge machining electrode 1 made of a platinum-iridium 33 w/o alloy and having a diameter of 0.5 mm and a length of 50 mm is used. The electrode 1' for electric discharge machining of the present invention is made by coating the surface of ceramic 4 with 0.1 mm of ceramic 4 and polishing the tip 1a to a sharp point at an angle of 10 degrees, and as shown in FIG. Diameter made of alloy
By using the conventional electrical discharge machining electrode 1, which has a diameter of 0.5 mm and a length of 50 mm, and the tip part 1a is sharpened and formed at an angle of 10 degrees, each diamond has a diameter of 0.03 mm and a depth of 0.3 mm.
When the degree of wear of the electrode was measured by drilling the die hole, the results shown in the table below were obtained.
【表】
上記の表で明らかなように実施例の放電加工用
電極１′は、消耗による再研摩までの使用時間は
従来例の放電加工用電極１と同じであるが、再研
摩による使用回数は従来例の放電加工用電極１の
2.5倍もあつて著しく多いことが判る。
以上詳記した通り本発明による放電加工用電極
は、放電の激しい電解液表面付近が絶縁体に被わ
れているので放電加工中電解液境界部からは放電
が起らない。従つて電解液境界部は消耗せず折損
することがないので、電極先端部を有効に使用で
きて、地金の無駄が無く、再研摩による使用回数
が数倍に増えて放電加工用電極の寿命が著しく増
長するという優れた効果がある。[Table] As is clear from the above table, the usage time of the electrical discharge machining electrode 1' of the example until re-polishing due to wear is the same as the conventional electrical discharge machining electrode 1, but the number of times it can be used due to re-polishing is the conventional electrical discharge machining electrode 1.
It can be seen that the number is 2.5 times higher, which is significantly higher. As detailed above, in the electrode for electric discharge machining according to the present invention, the vicinity of the surface of the electrolyte where intense electric discharge occurs is covered with an insulator, so that no electric discharge occurs from the boundary of the electrolyte during electric discharge machining. Therefore, the electrolyte boundary part does not wear out or break, so the tip of the electrode can be used effectively, there is no waste of metal, and the number of times it can be used due to re-polishing is increased several times, making it easier to use the electrode for electrical discharge machining. It has the excellent effect of significantly extending lifespan.
【図面の簡単な説明】[Brief explanation of drawings]
第１図は従来の放電加工用電極によるダイヤモ
ンドダイスの穴明け加工の状態をを示す図、第２
図，第３図は従来の放電加工用電極の電解液境界
部の放電による消耗過程を示す図、第４図は本発
明による放電加工用電極によるダイヤモンドダイ
スの穴明け加工の状態を示す図、第５図、第６図
は本発明の放電加工用電極の先端部の消耗過程を
示す図、第７図は本発明による放電加工用電極の
他の実施例を示す図、第８図は第７図の放電加工
用電極の先端部の消耗状態を示す図である。
１′……放電加工用電極、１ａ……先端部、１
ｂ……電解液境界部、４……セラミツク。
Figure 1 is a diagram showing the state of drilling a diamond die using a conventional electrical discharge machining electrode.
3 is a diagram showing the wear process due to discharge of the electrolyte boundary part of the conventional electric discharge machining electrode, and FIG. 4 is a diagram showing the state of drilling a diamond die using the electric discharge machining electrode according to the present invention. 5 and 6 are diagrams showing the wear process of the tip of the electrode for electrical discharge machining according to the present invention, FIG. 7 is a diagram showing another embodiment of the electrode for electrical discharge machining according to the present invention, and FIG. FIG. 8 is a diagram showing the state of wear of the tip of the electric discharge machining electrode shown in FIG. 7; 1'...Electrode for electric discharge machining, 1a...Tip part, 1
b... Electrolyte boundary part, 4... Ceramic.