JPS61293720A - Manufacture of carbon electrode for electric discharge machining - Google Patents

Abstract

PURPOSE:To manufacture a carbon electrode with high density further with an excellent electric discharge machining characteristic, by forming a molded dust, restricting a kind of carbon aggregate material and its grain size, to be fired. CONSTITUTION:A binding material is added to a carbon aggregate material consisting of 45-97pts.wt. pitch coke dust, 1-15pts.wt. graphite powder and 2-40pts.wt. carbon black being crushed with a maximum grain size in 15mum and averaged grading in 10mum or less. The method of manufacture, mixing said carbon aggregate material to be crushed, forms a molded dust. The method, pressurizing said molded dust to be formed performing firing at 1,000 deg.C and changing the dust into graphite at 2,700 deg.C, obtains an electrode for electric discharge machining. This carbon electrode is used, and the electrode, having small volume consumption ratio and enabling R in a corner to be decreased to a small value. enables roughness of a work machined surface to be decreased.

Description

【発明の詳細な説明】 （産業上の利用分野） 本発明は放電加工用炭素電極の製造法に関する。[Detailed description of the invention] (Industrial application field) The present invention relates to a method of manufacturing a carbon electrode for electrical discharge machining.

（従来の技術） を配合し、加熱捏和、冷却、粉砕、成形し、約１０００
℃で焼成し、更に必要により２５００〜３０００℃で二
次焼成（黒鉛化）する通常の人造黒鉛の製造法だ従って
製造され、高密度及び高強度を要するものは焼成品にピ
ッチ含浸及び焼成する工程を数回繰返している。又特公
昭５４−４００７４号公報に示されるように９粒子の小
さい炭素骨材にベンゼン不溶分とキノリンネ溶分との差
の大きいピッチを多量に加えて、緻密質の炭素電極を得
る方法がある。(conventional technology), heat-kneaded, cooled, crushed, and molded, approximately 1,000
This is the usual manufacturing method for artificial graphite, in which it is fired at a temperature of 2,500 to 3,000 degrees Celsius (graphitization) if necessary.Those that require high density and strength are impregnated with pitch in the fired product and fired. The process is repeated several times. Furthermore, as shown in Japanese Patent Publication No. 54-40074, there is a method of obtaining a dense carbon electrode by adding a large amount of pitch having a large difference between the benzene insoluble content and the quinoline soluble content to a small carbon aggregate of 9 particles. .

（発明の解決しようとする問題点） 高密度化するためにピッチ含浸及び焼成の工程を繰返す
方法は１例えば曲げ強さを例にとると４００　ｋａ／ｃ
ｗ’から５００に９に増大するが、この効果よりもピッ
チ含浸及び焼成の工数が大きくこれによるコストが上昇
する欠点を有する。またこのようにして得られた放電加
工用炭素電極は、放電加工を行なう際、銅電極に比較し
て荒加工では消耗が少ないが仕上加工では消耗が多く、
仕上面の粗さも１５〜２０μｍａｘが限界とされ、この
ため一般には荒加工には炭素電極、仕上加工には銅電極
というように使い分けされていた。(Problems to be Solved by the Invention) A method of repeating pitch impregnation and firing steps to increase density is 1. For example, taking the bending strength as an example, it is 400 ka/c.
Although w' increases from 500 to 9, this effect has the disadvantage that the number of man-hours for pitch impregnation and firing is greater and the cost increases accordingly. In addition, when performing electrical discharge machining, the carbon electrode for electrical discharge machining obtained in this way has less wear in rough machining than copper electrodes, but has more wear in finishing machining.
The roughness of the finished surface is also limited to 15 to 20 μmax, and for this reason, carbon electrodes are generally used for rough machining, and copper electrodes are used for finishing machining.

特公昭５４−４００７４号公報によって得られる炭素電
極は仕上加工、精密加工にも適するが。The carbon electrode obtained by Japanese Patent Publication No. 54-40074 is also suitable for finishing and precision processing.

炭素骨材を微細化するためにコストが増大し、又結合材
を多量に使用するので揮発分調整が困難となって先度歩
留が悪いという欠点があった。Since the carbon aggregate is made finer, the cost increases, and since a large amount of binder is used, it is difficult to adjust the volatile content, which leads to a poor yield.

本発明は上記した欠点を解消する放電加工用炭素電極の
製造法を提供することを目的とする。An object of the present invention is to provide a method for manufacturing a carbon electrode for electric discharge machining that eliminates the above-mentioned drawbacks.

（問題点を解決するための手段） 本発明者らは、炭素骨材の稲類９粒径、配合割合につい
て研究を重ねた結果、これらを組合せることによシ、緻
密高強度で精密仕上加工も可能で消耗の少ない放電加工
用炭素電極が得られることを見い出した。(Means for Solving the Problems) As a result of repeated research on the nine grain sizes and blending ratios of carbon aggregates, the present inventors found that by combining these, it is possible to achieve a dense, high-strength, and precision finish. It was discovered that a carbon electrode for electrical discharge machining that can be processed and has little wear and tear can be obtained.

本発明は、最大粒径が１５μｍで平均粒径が１０μｍ以
下のピッチコークス粉及び黒鉛粉、前記ピッチコークス
粉の平均粒径の０．４倍以下の粒度を有スるカーボンブ
ラックからなる炭素骨材に結合材を加え、捏和、粉砕し
て成形粉を得２次いで該成形粉を成形し、焼成する放電
加工用炭素電極の製造法に関する。The present invention provides carbon bones made of pitch coke powder and graphite powder having a maximum particle size of 15 μm and an average particle size of 10 μm or less, and carbon black having a particle size of 0.4 times or less than the average particle size of the pitch coke powder. The present invention relates to a method for producing a carbon electrode for electric discharge machining, which involves adding a binder to a material, kneading and pulverizing it to obtain a molded powder, and then molding and firing the molded powder.

本発明においてピッチコークス粉及び黒鉛粉の平均粒径
が１０μｍを越えると緻密な組織の炭素電極が得られず
、又最大粒径が１５μｍを越えると得られる炭素電極中
に塊状のものが生じ、放電加工をしたときに面荒れの原
因となる。In the present invention, if the average particle size of pitch coke powder and graphite powder exceeds 10 μm, a carbon electrode with a dense structure cannot be obtained, and if the maximum particle size exceeds 15 μm, lumps will occur in the obtained carbon electrode. It causes surface roughness during electrical discharge machining.

カーボンブラックはピッチコークス粉及び黒鉛粉の粒子
間隙に分散して空隙を小さくし密な充填状態にするため
に加えるもので、その粒度はピッチコークス粉の平均粒
径の０．４倍以下とされる。Carbon black is added to disperse into the gaps between particles of pitch coke powder and graphite powder to reduce the voids and create a densely packed state, and its particle size is 0.4 times or less the average particle size of pitch coke powder. Ru.

０．４倍を越えると炭素骨材の密な充填が困難となシ、
緻密な炭素電極が得られない。好ましい粒径はｌＯ〜５
００　ｎｍである。カーボンブラックの種類はサーマル
ブラック、ランプブラック、ファーネスブラック等のい
ずれでもよい。If it exceeds 0.4 times, it will be difficult to densely fill the carbon aggregate.
A dense carbon electrode cannot be obtained. The preferred particle size is lO~5
00 nm. The type of carbon black may be thermal black, lamp black, furnace black, etc.

炭素骨材の好ましい配合組成は、ピッチコークス粉４５
〜９７重量部、黒鉛粉１〜１５重量部重量部及ヒソ−ホ
ンプラック２〜４０である。この範囲の組成とすること
によって前記したようにピッチコークス粉及び黒鉛粉の
粒子間隙にカーボンブラックを充填して緻密な組織にす
るもので、カーボンブラックの量が少なすぎるとこの効
果がなく、多すぎると結合材の必要量が多くなシ亀裂。A preferable blending composition of the carbon aggregate is pitch coke powder 45
~97 parts by weight, 1 to 15 parts by weight of graphite powder, and 2 to 40 parts by weight of Hisophone plaque. By setting the composition within this range, as mentioned above, carbon black is filled into the interparticle spaces of pitch coke powder and graphite powder to form a dense structure.If the amount of carbon black is too small, this effect will not be achieved, If it is too much, the amount of bonding material required will be large.

ふくれ等が発生し易く密度も低下してくる。黒鉛粉はピ
ッチコークス粉及びカーボンブラックの熱処理時の収縮
の際に生じ易い亀裂を防止するために加えるもので、少
ないと効果がなく、多すぎると機械的強度が低下し易く
なる。Blisters and the like tend to occur and the density decreases. Graphite powder is added to prevent cracks that are likely to occur when pitch coke powder and carbon black shrink during heat treatment, and if there is too little, there is no effect, and if there is too much, the mechanical strength tends to decrease.

前記炭素骨材と配合する結合剤は主にピッチ。The binder mixed with the carbon aggregate is mainly pitch.

タールを用い、その量は重量で炭素骨材１００部に対し
９０−１５０部が好ましい。結合材が少ないと緻密でか
つ特性の均一のものが得難くなり。Preferably, tar is used in an amount of 90 to 150 parts by weight per 100 parts of carbon aggregate. If there is less binding material, it will be difficult to obtain a product that is dense and has uniform properties.

多すぎると焼成の過程で亀裂、ふくれ等が発生し易い。If there is too much, cracks, blisters, etc. are likely to occur during the firing process.

炭素骨材と結合材との捏和（混線ともいう）は双腕型捏
和機等を用いて公知の方法で行なう。混線物は公知の方
法で粉砕して成形粉を得るが、成形粉は平均粒径１５μ
ｍ以下のものが好ましい。Kneading (also referred to as cross-mixing) of the carbon aggregate and the binder is performed by a known method using a double-arm kneader or the like. The mixed material is crushed by a known method to obtain molded powder, and the molded powder has an average particle size of 15 μm.
m or less is preferable.

粒径が大きくなると得られる炭素型砂中に塊状のものが
生じ、放電加工時に面荒れの原因となり易い。When the particle size becomes large, lumps are formed in the obtained carbon type sand, which tends to cause surface roughness during electrical discharge machining.

成形、焼成（黒鉛化を含む）は公知の方法にょシ、特に
制限はない。Molding and firing (including graphitization) may be carried out by known methods, and there are no particular limitations.

（実施例） 次に本発明の詳細な説明する。(Example) Next, the present invention will be explained in detail.

実施例１ 最大粒径１５μｍで平均粒径が８μｍに粉砕した石炭系
ピッチコークスの粉末７５１ｉＣ量部、ピッチコークス
粉と同じ粒度のコークス系人造黒鉛粉５重量部及び平均
粒径３００　ｎｍの自家製ランプブラック２０重量部か
らなる炭素骨材と軟化点８０℃のタールピッチ（ＪＩＳ
　　Ｋ　　２４３９．一般用中ピツチ）及びエングラ粘
度８のコールタール（ＪＩＳ　　Ｋ　　２４３９．精製
タール１号）からなる結合材とを双腕型捏和機に入れ、
２４０℃まで加熱して４時間混練した。この混練物を粉
砕機によシ平均粒径１２μｍに粉砕し、加圧成形後。Example 1 751 iC parts of coal-based pitch coke powder pulverized to a maximum particle size of 15 μm and an average particle size of 8 μm, 5 parts by weight of coke-based artificial graphite powder with the same particle size as pitch coke powder, and a homemade lamp with an average particle size of 300 nm. Carbon aggregate consisting of 20 parts by weight of black and tar pitch with a softening point of 80°C (JIS
K 2439. A binder consisting of coal tar (JIS K 2439. Refined tar No. 1) with a viscosity of 8 is placed in a double-arm kneading machine.
The mixture was heated to 240°C and kneaded for 4 hours. This kneaded material was pulverized by a pulverizer to an average particle size of 12 μm, and then pressure molded.

１０００℃で焼成、２７００℃で黒鉛化を行なった。Firing was performed at 1000°C, and graphitization was performed at 2700°C.

比較例１ 実施例１と同一粒度のピッチコークス粉９５重景部、実
施例１と同一粒度の人造黒鉛粉５重量部実施例１と同一
のタールピッチ７０重量部及び実施例１と同一のコール
タール３０重量部を実施例１と同様にして混練、粉砕、
成形及び焼成したところ焼成品にふくれが発生した。Comparative Example 1 95 parts by weight of pitch coke powder with the same particle size as Example 1, 5 parts by weight of artificial graphite powder with the same particle size as Example 1, 70 parts by weight of tar pitch the same as Example 1, and the same coal as Example 1 30 parts by weight of tar was kneaded and pulverized in the same manner as in Example 1.
When molded and fired, the fired product blistered.

比較例２ 比較例１の炭素骨材１００重量部に実施例１と同一のタ
ールピッチ及びコールタールを各々６５重量部及び２５
重量部を加えて、実施例１と同様にして混線、粉砕、成
形、焼成及び黒鉛化を行なった。Comparative Example 2 To 100 parts by weight of the carbon aggregate of Comparative Example 1, 65 parts by weight and 25 parts by weight of the same tar pitch and coal tar as in Example 1 were added.
After adding parts by weight, the mixture was mixed, crushed, molded, fired, and graphitized in the same manner as in Example 1.

実施例２ 最大粒径１５μｍで平均粒径が２μｍに粉砕した石炭系
ピッチコークスの粉末８０重量部、ピッチコークス粉と
同じ粒度のコークス系人造黒鉛粉１０重量部及び平均粒
径４０　ｎｍのファーネスブラック１０重量部からなる
炭素骨材に、実施例１と同一のタールピッチ１００重量
部及び実施例１と同一のコールタール４０重量部からな
る結合材とを双腕型捏和機に入れ、実施例１と同様にし
て混線後粉砕して平均粒径４μｍの成形粉を得、以下実
施例１と同一条件で加圧成形、焼成及び黒鉛化を行なっ
た。Example 2 80 parts by weight of coal-based pitch coke powder pulverized to a maximum particle size of 15 μm and an average particle size of 2 μm, 10 parts by weight of coke-based artificial graphite powder with the same particle size as the pitch coke powder, and furnace black with an average particle size of 40 nm. 10 parts by weight of carbon aggregate, 100 parts by weight of the same tar pitch as in Example 1, and a binder consisting of 40 parts by weight of coal tar, the same as in Example 1, were placed in a double-arm kneading machine. The mixture was mixed and then pulverized in the same manner as in Example 1 to obtain a molded powder with an average particle size of 4 μm, followed by pressure molding, firing, and graphitization under the same conditions as in Example 1.

実施例及び比較例２で得られた炭素電極の物理特性を第
１表に示す。Table 1 shows the physical properties of the carbon electrodes obtained in Example and Comparative Example 2.

第１表 第１表から実施例の炭素電極は比較例のものに比して高
密度及び高強度であることがわかる。Table 1 It can be seen from Table 1 that the carbon electrodes of Examples have higher density and strength than those of Comparative Examples.

又実施例及び比較例２で得られた炭素電極について、第
２表に示す３条件によシ放電加工試験を行なった。放電
加工機はスイス製のＣｈａｒｍｉｌｅｓｓＤＩＴ、電源
はＣｈａｒｍｉｌｅｓｓ　　Ｐ　１０３を用いた。Further, the carbon electrodes obtained in Examples and Comparative Example 2 were subjected to electrical discharge machining tests under the three conditions shown in Table 2. The electrical discharge machine used was Charmiless DIT made in Switzerland, and the power supply was Charmiless P 103.

試験結果を第３表に示す。The test results are shown in Table 3.

第２表 第３表 第３表から明らかなように実施例の炭素電極を用いれば
１体積消耗比が小さく、コーナーのＲを小さくすること
ができ、ワークの加工面の粗さを小さくできる。加工速
度はやや小さいがこれは放電条件によって改善できるも
のである。As is clear from Table 2, Table 3, and Table 3, when the carbon electrode of the example is used, the 1 volume consumption ratio is small, the radius of the corner can be made small, and the roughness of the machined surface of the workpiece can be made small. The machining speed is somewhat slow, but this can be improved by changing the discharge conditions.

（発明の効果） 本発明によれば、高密度で放電加工特性に優れた炭素電
極が得られる。(Effects of the Invention) According to the present invention, a carbon electrode with high density and excellent electrical discharge machining characteristics can be obtained.

代理人　弁理士　若　林　邦　彦 ＼穎本争Agent Patent Attorney Kunihiko Wakabayashi ＼Emoto battle

Claims (1)

【特許請求の範囲】[Claims] １、最大粒径１５μｍで平均粒径が１０μｍ以下のピッ
チコークス粉及び黒鉛粉、前記ピッチコークス粉の平均
粒径の０．４倍以下の粒度を有するカーボンブラックか
らなる炭素骨材に結合材を加え、捏和、粉砕して成形粉
を得、次いで該成形粉を成形し、焼成することを特徴と
する放電加工用炭素電極の製造法。1. A binder is added to carbon aggregate made of pitch coke powder and graphite powder with a maximum particle size of 15 μm and an average particle size of 10 μm or less, and carbon black with a particle size of 0.4 times or less than the average particle size of the pitch coke powder. In addition, a method for manufacturing a carbon electrode for electrical discharge machining, which comprises kneading and pulverizing to obtain a molded powder, then molding and firing the molded powder.