JPH05116032A - Manufacture of electric discharge machining electrode - Google Patents
Manufacture of electric discharge machining electrodeInfo
- Publication number
- JPH05116032A JPH05116032A JP21802691A JP21802691A JPH05116032A JP H05116032 A JPH05116032 A JP H05116032A JP 21802691 A JP21802691 A JP 21802691A JP 21802691 A JP21802691 A JP 21802691A JP H05116032 A JPH05116032 A JP H05116032A
- Authority
- JP
- Japan
- Prior art keywords
- electrode
- discharge machining
- electric discharge
- mixture
- average particle
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- Electrical Discharge Machining, Electrochemical Machining, And Combined Machining (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は放電加工用グラファイト
電極の製造方法に関する。更に詳しくは、放電加工の際
の電極消耗が少い放電加工用グラファイト電極の製造方
法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a graphite electrode for electric discharge machining. More specifically, the present invention relates to a method for manufacturing a graphite electrode for electric discharge machining, which causes less electrode consumption during electric discharge machining.
【０００２】[0002]
【従来の技術】放電加工電極用グラファイトの消耗は、
自身の機械強度や硬度が高いほど小さくなる傾向があ
り、消耗の低減を図るためには嵩密度を高めて機械強度
や硬度を向上させるのが一般的であった。製造方法とし
ては、ピッチコークスや石油コークスなどの炭素質原料
を微粉砕し、タールやピッチなどのバインダー（結合
剤）と共に加熱捏合して混合物とし、これを再粉砕後Ｃ
ＩＰ成形し、焼成・黒鉛化して製造する方法が多く行わ
れており、この場合、再粉砕粒度が細か過ぎると、充填
密度が低下し得られる製品の嵩密度も低下してしまうた
め、製品の嵩密度ができるだけ高くなるように粒度調製
するのが一般的であった。2. Description of the Related Art The consumption of graphite for electrical discharge machining electrodes is
The higher the mechanical strength and hardness of itself, the smaller it tends to be, and in order to reduce the wear, it is common to increase the bulk density to improve the mechanical strength and hardness. As a manufacturing method, carbonaceous raw materials such as pitch coke and petroleum coke are finely pulverized, and the mixture is heated and kneaded with a binder (binding agent) such as tar and pitch to obtain a mixture.
There are many methods of manufacturing by IP molding, firing and graphitization. In this case, if the re-grinding particle size is too fine, the packing density decreases and the bulk density of the obtained product also decreases. It was common to control the particle size so that the bulk density was as high as possible.
【０００３】[0003]
【発明が解決しようとする課題】本発明の目的は、電極
消耗が小さい放電加工用グラファイト電極を提供するこ
とにある。（以後放電加工用グラファイト電極を単に電
極と呼ぶ）前述のように、放電加工における電極消耗は
電極の機械強度および硬度と関係があり、消耗を小さく
するためには、電極を緻密化して機械強度および硬度を
高める方法が採られてきた。しかし、電極は放電加工の
形状に応じて機械加工するため、硬度が高いと切削性が
低下して工具の消耗が大きくなるほか、加工精度が悪く
なる問題があった。また、電極を緻密化するためには、
焼成・黒鉛化時の収縮を大きくする必要があり、割れ不
良率が増加することも問題であった。SUMMARY OF THE INVENTION It is an object of the present invention to provide a graphite electrode for electric discharge machining which consumes less electrode. (Hereinafter, the graphite electrode for electrical discharge machining is simply referred to as an electrode.) As described above, the electrode wear in electrical discharge machining is related to the mechanical strength and hardness of the electrode. And methods of increasing hardness have been adopted. However, since the electrode is machined according to the shape of the electric discharge machining, if the hardness is high, the machinability is deteriorated, the tool is consumed more, and the machining accuracy is deteriorated. Moreover, in order to make the electrode dense,
It was necessary to increase shrinkage during firing and graphitization, and there was also a problem that the crack failure rate increased.
【０００４】[0004]
【課題を解決するための手段】本発明者らは前記の課題
を解決するため鋭意研究を行った結果、捏合物の粉砕粒
径をコントロールすることで電極消耗を大幅に低減でき
ることを見い出した。As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that the consumption of electrodes can be greatly reduced by controlling the crushed particle size of the kneaded product.
【０００５】すなわち本発明は 平均粒径が１０μｍ以下に粉砕された炭素質原料と
結合材を加熱捏合して得られる混合物を、炭素質原料の
平均粒径の１００〜１５０％の平均粒径に粉砕しＣＩＰ
成形して焼成・黒鉛化することを特徴とする放電加工用
グラファイト電極の製造方法であり、That is, according to the present invention, a mixture obtained by heating and kneading a carbonaceous raw material pulverized to an average particle diameter of 10 μm or less and a binder is made to have an average particle diameter of 100 to 150% of the average particle diameter of the carbonaceous raw material. Crushed CIP
A method for producing a graphite electrode for electric discharge machining, which comprises molding, firing and graphitizing,
【０００６】 平均粒径が炭素質原料の１００〜１５
０％である混合物を分級して得ることを特徴とする前項
１記載の放電加工用グラファイト電極の製造方法であ
る。The average particle size of the carbonaceous raw material is 100 to 15
The method for producing a graphite electrode for electric discharge machining according to item 1, wherein the mixture is obtained by classifying a mixture of 0%.
【０００７】本発明の方法によれば、電極の嵩密度は大
幅に低下するが、意外にも、放電加工時の電極消耗を大
幅に低減できることが分った。この場合、嵩密度は低下
するため、硬度の上昇や、焼成・黒鉛化時の割れ不良率
の増加の問題は完全に解決される。本発明の炭素質原料
の平均粒径は約１０μｍ以下、好ましくは５μｍ以下で
あることが必要である。According to the method of the present invention, the bulk density of the electrode is significantly reduced, but it was surprisingly found that the electrode consumption during electric discharge machining can be significantly reduced. In this case, since the bulk density is lowered, the problems of increased hardness and crack failure rate during firing / graphitization are completely solved. The average particle size of the carbonaceous raw material of the present invention needs to be about 10 μm or less, preferably 5 μm or less.
【０００８】本発明においては炭素質原料の平均粒径が
大きくなるほど電極消耗の低減効果は減少し、１０μｍ
を超える平均粒径では期待される低消耗の電極を得るこ
とができない。更に、炭素質原料の平均粒径が５μｍ以
下では、本発明の効果が極めて顕著となる。In the present invention, the larger the average particle size of the carbonaceous raw material is, the smaller the effect of reducing the electrode consumption is, and
If the average particle size exceeds, it is not possible to obtain the expected low consumption electrode. Furthermore, when the average particle size of the carbonaceous raw material is 5 μm or less, the effect of the present invention becomes extremely remarkable.
【０００９】さて、電極の組織構造は混合物の平均粒径
が炭素質原料の平均粒径に近いほど均一になり、それに
従って電極消耗は小さくなる。しかし、炭素質原料の平
均粒径の１００％より小さく粉砕すると、混合物中の炭
素質原料が元の粒径より小さく粉砕されて新しい破面が
増加するため、結合剤が不足となって電極中の炭素質原
料の粒子の結合力が低下し電極消耗が増加に転じる。た
だし、元々結合剤が過剰の場合はこの限りではない。一
方、１５０％を越えると電極の組織構造が不均一とな
り、充分な電極消耗低減の効果が得られなくなる。The structure of the electrode becomes more uniform as the average particle size of the mixture becomes closer to the average particle size of the carbonaceous raw material, and the electrode consumption decreases accordingly. However, if the carbonaceous raw material is pulverized to be smaller than 100% of the average particle diameter, the carbonaceous raw material in the mixture is pulverized to be smaller than the original particle diameter and a new fracture surface is increased. The binding force of the particles of the carbonaceous raw material is decreased, and the consumption of the electrode is increased. However, this does not apply when the binder is originally excessive. On the other hand, if it exceeds 150%, the tissue structure of the electrode becomes nonuniform, and the effect of sufficiently reducing the electrode wear cannot be obtained.
【００１０】本発明では、混合物の平均粒径の調整を、
炭素質原料粒子の１００％以上の平均粒径に粉砕した混
合物を分級して行っても低消耗電極を製造することがで
きる。しかし、分級で得られた混合物の粒径分布は出来
るだけ滑らかに変化していることが必要であり、例え
ば、極端に粒径の異なる粗粉と微粉の配合によって平均
粒径を調製したものでは本発明の効果は得られない。特
に５０μｍより大きな混合物粒子は含まれないことが望
ましい。ところで、混合物の平均粒径の分級で行う場合
には、混合物の平均粒径が炭素質原料のそれより小さく
なることもある。しかし、この場合の混合物粒子は、上
述したような新しい破面を形成していないと考えられ、
したがって得られる電極中の炭素質原料の粒子の結合力
の低下が殆ど無いため充分な電極消耗低減の効果を得る
ことができる。In the present invention, the average particle size of the mixture is adjusted by
A low consumption electrode can be manufactured even by classifying a mixture obtained by pulverizing carbonaceous raw material particles to an average particle size of 100% or more. However, the particle size distribution of the mixture obtained by classification needs to change as smoothly as possible.For example, in the case where the average particle size is adjusted by mixing coarse powder and fine powder with extremely different particle sizes, The effect of the present invention cannot be obtained. In particular, it is desirable not to include mixed particles larger than 50 μm. By the way, when classifying the average particle size of the mixture, the average particle size of the mixture may be smaller than that of the carbonaceous raw material. However, it is considered that the mixture particles in this case do not form a new fracture surface as described above,
Therefore, there is almost no decrease in the binding force of the particles of the carbonaceous raw material in the obtained electrode, and the effect of sufficiently reducing the electrode consumption can be obtained.
【００１１】[0011]
【作用】本発明の作用については明かでないが、得られ
る電極の組織構造が極めて均一化され、消耗が小さな組
織単位で逐次的に進むことが良い結果をもたらすものと
考えられる。Although the function of the present invention is not clear, it is considered that the tissue structure of the obtained electrode is made extremely uniform, and that it is possible to obtain good results by sequentially advancing in tissue units with small wear.
【００１２】[0012]
【実施例】以下に実施例により本発明を更に具体的に説
明するが、本発明はこの実施例によって何等限定される
ものではない。The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.
【００１３】（実施例１）ピッコークスを平均粒径約
５．０μｍに粉砕し、軟化点９２℃のコールタール系硬
ピッチとともに加熱捏合して混合物を得た。この混合物
を予備粉砕後ジェット粉砕機により平均粒径約５．８μ
ｍに粉砕し、直径１２０φのゴム型に充填して圧力１t/
cm2 でＣＩＰ成形した。得られた成型体を９５０℃で焼
成後、約３０００℃で黒鉛化して電極試料とした。放電
加工評価条件は次の通り。 電極サイズ ：２０φ×６０ｍｍ（１φ加工液噴射孔
付） ピーク電流値：２０Ａ 通電時間 ：５５μｓｅｃ 休止時間 ：５５μｓｅｃ 電極は物性値および放電加工特性は他の実施例、比較例
とともに表１、表２に示した。Example 1 Piccokes were pulverized to an average particle size of about 5.0 μm and kneaded with a coal tar hard pitch having a softening point of 92 ° C. by heating to obtain a mixture. After preliminarily crushing this mixture, the average particle size was about 5.8μ with a jet crusher.
It is crushed to m and filled in a rubber mold with a diameter of 120φ and the pressure is 1 t /
CIP molding was performed at cm 2 . The obtained molded body was fired at 950 ° C. and graphitized at about 3000 ° C. to obtain an electrode sample. The electrical discharge machining evaluation conditions are as follows. Electrode size: 20φ × 60 mm (with 1φ machining fluid injection hole) Peak current value: 20 A Energizing time: 55 μsec Rest time: 55 μsec Electrode physical properties and electrical discharge machining characteristics are shown in Tables 1 and 2 along with other examples and comparative examples. Indicated.
【００１４】（実施例２）（比較例１） 実施例１と同様な方法で得た混合物をアトマイザーで平
均粒径約２３μｍに粉砕後、風力分級機でおよそ１０
０、５０、２０μｍの区切りで分級した。それぞれを実
施例１と同様にＣＩＰ成形、焼成、黒鉛化して放電加工
評価を行った。電極の物性値および放電加工特性は他の
実施例、比較例とともに表１、表２に示した。表１に示
した如く、２０μｍ以下の分級物は平均粒径３．１μｍ
であり、５０μｍ以下の分級物は平均粒径５．９μｍで
あり、ピッチコークスの平均粒径５．０μｍよりみて、
本発明方法のものであるが、１００μｍ以下の分級物は
平均粒径１６．２μｍで、比較例１である。(Example 2) (Comparative Example 1) The mixture obtained by the same method as in Example 1 was pulverized with an atomizer to an average particle size of about 23 μm, and then with an air classifier to about 10
Classification was performed at intervals of 0, 50 and 20 μm. Each of them was subjected to CIP molding, firing and graphitization in the same manner as in Example 1 and evaluated for electrical discharge machining. The physical properties and the electric discharge machining characteristics of the electrode are shown in Tables 1 and 2 together with other examples and comparative examples. As shown in Table 1, the classified particles of 20 μm or less have an average particle size of 3.1 μm.
The average particle size of the classified product of 50 μm or less is 5.9 μm, and the average particle size of the pitch coke is 5.0 μm.
The classified product of the method of the present invention has a mean particle size of 16.2 μm and is classified as Comparative Example 1.
【００１５】（比較例２）実施例２で調製した平均粒径
約２３μｍの混合物を実施例１と同様にＣＩＰ成形、焼
成、黒鉛化して放電加工評価を行った。電極の物性値お
よび放電加工特性は他の実施例、比較例とともに表１、
表２に示した。Comparative Example 2 The mixture prepared in Example 2 and having an average particle size of about 23 μm was subjected to CIP molding, firing and graphitization in the same manner as in Example 1 and evaluated for electrical discharge machining. The physical properties and the electric discharge machining characteristics of the electrodes are shown in Table 1 together with other examples and comparative examples.
The results are shown in Table 2.
【００１６】表２に示した電極消耗比（％）、面粗さ
（Ｒmax μｍ）、加工速度(g/min) 、は夫々次の測定法
による。 (1) 電極消耗比（γο％） 加工終了後の電極消耗長さと工作物の長さの比The electrode consumption ratio (%), surface roughness (Rmax μm) and processing speed (g / min) shown in Table 2 are measured by the following measuring methods. (1) Electrode wear ratio (γο%) Ratio of electrode wear length and work length after machining
【数１】 [Equation 1]
【００１７】(2) 面粗さ（Ｒmax ） 面粗さ計により測定される工作物の面の極大値と極小値
の差即ち面粗さＲmax （μｍ）（図２参照）(2) Surface roughness (Rmax) The difference between the maximum value and the minimum value of the surface of the workpiece measured by the surface roughness meter, that is, the surface roughness Rmax (μm) (see FIG. 2).
【００１８】(3) 加工速度（Ｗoc） １分間当りの工作物の重量変化 （工作物を深さ３mm加工して測定） (3) Machining speed (Woc) Weight change of the workpiece per minute (measured by machining the workpiece to a depth of 3 mm)
【００１９】[0019]
【表１】 [Table 1]
【００２０】[0020]
【表２】 [Table 2]
【００２１】以上のように本発明の効果によって電極の
消耗が著しく低減できる。その他の効果として加工速度
は落ちる反面、加工面の粗さが小さくなる利点がある。As described above, the effects of the present invention can significantly reduce the consumption of electrodes. Another effect is that the processing speed is reduced, but the roughness of the processed surface is reduced.
【００２２】[0022]
【発明の効果】黒鉛電極製造過程における２次粉砕時の
平均粒径を、最初の炭素質原料の平均粒径との関連によ
り１００〜１５０％の平均粒径となるように調整する
か、そのような平均粒径となるよう分級することによっ
て、得た粉砕物をＣＩＰ成形、焼成、黒鉛化した電極を
使用することにより、放電加工における電極消耗を大幅
に低減させることができ、ワーク面粗さも小さくするこ
とができた。放電加工電極の改良としての効果は大き
い。The average particle size at the time of secondary crushing in the graphite electrode manufacturing process is adjusted so as to have an average particle size of 100 to 150% in relation to the average particle size of the first carbonaceous raw material, or By using an electrode obtained by classifying the obtained pulverized product by CIP molding, firing, and graphitization by classifying so as to have such an average particle size, it is possible to greatly reduce electrode consumption in electric discharge machining, and to roughen the work surface. I was able to reduce it too. The effect of improving the electric discharge machining electrode is great.
【図１】工作物Ｂを放電電極Ａで放電加工する断面立面
略図である。FIG. 1 is a schematic sectional elevational view of electric discharge machining of a workpiece B with an electric discharge electrode A.
【図２】工作物の工作面の面粗さを面粗さ計で測定する
断面立面説明図である。FIG. 2 is an explanatory sectional elevation view in which the surface roughness of the work surface of the workpiece is measured by a surface roughness meter.
Ａ 電極 Ｂ 工作物 Ｇ 電極の直径 Ｘ 電極の最初の長さ Ｘ1 加工終了時の長さ Ｙ 工作深さ δ 拡大代A Electrode B Workpiece G Electrode diameter X Initial length of electrode X 1 Length at the end of machining Y Machining depth δ Expansion allowance
───────────────────────────────────────────────────── フロントページの続き (72)発明者 堀田 典男 宮城県仙台市泉区将監８丁目14−３−201 (72)発明者 佐藤 昌宏 宮城県塩釜市清水沢３丁目25−２−833 (72)発明者 森川 文人 宮城県仙台市泉区将監２丁目３−６−201 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Norio Horita 8-14-3-201, General Manager Izumi-ku, Sendai-shi, Miyagi Prefecture (72) Masahiro Sato 3-chome 25-2-833, Shimizuzawa, Shiogama-shi, Miyagi Prefecture (72) Inventor Fumito Morikawa 3-6-201 General Manager 2-chome, Izumi-ku, Sendai City, Miyagi Prefecture
Claims (2)
素質原料と結合材を加熱捏合して得られる混合物を、炭
素質原料の平均粒径の１００〜１５０％の平均粒径に粉
砕し、ＣＩＰ成形して焼成・黒鉛化することを特徴とす
る放電加工用グラファイト電極の製造方法。1. A mixture obtained by heating and kneading a carbonaceous raw material pulverized to an average particle diameter of 10 μm or less and a binder is pulverized to an average particle diameter of 100 to 150% of the average particle diameter of the carbonaceous raw material. A method for manufacturing a graphite electrode for electric discharge machining, which comprises CIP molding, firing and graphitization.
％である混合物を分級して得ることを特徴とする請求項
１記載の放電加工用グラファイト電極の製造方法。2. A carbonaceous raw material having an average particle size of 100 to 150.
The method for producing a graphite electrode for electric discharge machining according to claim 1, wherein the mixture is obtained by classifying the mixture.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP03218026A JP3121053B2 (en) | 1991-08-05 | 1991-08-05 | Manufacturing method of electric discharge machining electrode |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP03218026A JP3121053B2 (en) | 1991-08-05 | 1991-08-05 | Manufacturing method of electric discharge machining electrode |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH05116032A true JPH05116032A (en) | 1993-05-14 |
| JP3121053B2 JP3121053B2 (en) | 2000-12-25 |
Family
ID=16713475
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP03218026A Expired - Fee Related JP3121053B2 (en) | 1991-08-05 | 1991-08-05 | Manufacturing method of electric discharge machining electrode |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3121053B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100354864B1 (en) * | 2000-08-22 | 2002-10-05 | 강신일 | Method of carbon cathode fabrication for micro-electric discharge machining |
-
1991
- 1991-08-05 JP JP03218026A patent/JP3121053B2/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100354864B1 (en) * | 2000-08-22 | 2002-10-05 | 강신일 | Method of carbon cathode fabrication for micro-electric discharge machining |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3121053B2 (en) | 2000-12-25 |
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