JPH09239622A - Aerial electric dischage machining method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accelerate machining speed without wearing electrodes by injecting pressure gas containing gas chemically reacting with workpieces as machining medium in the gap between the electrode and the workpiece so that it is forcibly made to flow in an approximately cross direction. SOLUTION: The pressure gas sent from a chuck section or the like into an electrode cylinder is injected so that it is forcibly made flow in the cross direction of the face to be machined which has a thin wall thickness of approximately 0.05 to 3mm from the gap between the face to be machined in the machining area of the workpiece, and discharges the fused machining chips produced due to electrical discharge and chemically reacts with the machining chips and in addition, cools the area to be machined while pulsed voltage is not applied. The workpiece 9 can be given translation motion or vibration motion whose radius is the same as the wall thickness of the electrode 1 or less in addition to the rotation relative to the electrode 1.

Description

【発明の詳細な説明】Detailed Description of the Invention

【０００１】[0001]

【発明の属する技術分野】本発明は、金型工作法等とし
て有用な放電加工方法及びその装置の改良に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric discharge machining method and a device therefor which are useful as a die machining method and the like.

【０００２】[0002]

【従来の技術】放電加工は、機械力を直接被加工体に作
用させて加工を行なう通常の機械加工と異なり、被加工
体と加工電極との間の加工液が介在する間隙に休止時間
を置いた電圧パルス印加し、その際に生じる放電現象を
利用する非接触加工法として知られて居り、そしてその
加工方法及び装置としては、上記加工電極として棒状や
総型電極を用いて穿孔や型彫加工を行なう所謂ラム型放
電加工と、上記加工電極として軸方向に連続的に更新送
りされるワイヤ電極を用いて糸鋸状の切り出し加工を行
なうワイヤ放電加工、そして近時、上記ラム型放電加工
の加工電極として比較的単純形状の棒状電極を用い、加
工時に対向方向と直角方向に所望加工領域にわたって相
対的に移動させて表面及び所望形状のキャビティ加工を
するようにする創成加工方法等が良く知られている。2. Description of the Related Art EDM differs from ordinary machining in which mechanical force is directly applied to a workpiece to perform machining, and a dwell time is provided in a gap between the workpiece and a machining electrode in which a machining fluid intervenes. It is known as a non-contact processing method that applies a voltage pulse placed and uses the discharge phenomenon that occurs at that time, and as the processing method and device, there is a hole or die using a rod-shaped or formed electrode as the processing electrode. So-called ram-type electric discharge machining that performs engraving, wire-electric discharge machining that performs wire saw-shaped cutting using wire electrodes that are continuously renewed and fed in the axial direction as the machining electrodes, and recently, the ram-type electric discharge machining described above. A rod-shaped electrode having a relatively simple shape is used as the machining electrode for the machining, and the machining is performed by relatively moving the machining electrode in a direction perpendicular to the facing direction over the desired machining area to machine the cavity of the surface and the desired shape. Processing method and the like are well known.

【０００３】そして、上記の如き各加工の場合、通常必
ず加工電極と被加工体間の微細間隙を隔てて形成される
放電間隙には鉱油系加工液や水系加工液等の加工液が放
電媒体として介在乃至は流通介在せしめられている。加
工液の放電加工に対する役割は、放電柱を周りから冷
却、そして膨脹を押さえ、放電エネルギ密度を高め、発
生する爆発衝撃力を増大させ、電極及び被加工体の各放
電点の溶融物を飛散させ、金属蒸気及び金属溶物の飛散
を増加させる。又、加工液は、放電によって電極及び被
加工体から生成、飛散する加工屑を急冷して固化させ、
粒子化し、電極・被加工体への付着を防止し、且つ、加
工屑の移動を容易にして放電の発生、放電点の移動をう
ながし、放電間隙長を増大させる。又、冷却作用、及び
使用加工液、電極、被加工体の組合せによっては、加工
液の分解によって生成したパイログラファイト等を電極
の加工面に付着させて電極の消耗を防止、低減させる。
そして主に電圧パルス間の放電休止期間中であるが、そ
の液流によって加工及び分解による加工屑、タール、ガ
ス等の一部以上を放電間隙外へ排出して、次の電圧パル
ス印加に基づく間隙での発生放電を正常なものとし、所
期の加工作用が継続して行なわれるように作用してい
る。In each of the above-described machining processes, a working fluid such as a mineral oil-based working fluid or a water-based working fluid is usually used as a discharge medium in the discharge gap which is always formed with a fine gap between the machining electrode and the workpiece. As an intervening or distribution intervening. The role of the machining fluid in electrical discharge machining is to cool the discharge column from the surroundings and suppress expansion, increasing the discharge energy density, increasing the explosive impact force generated, and scattering the molten material at each discharge point of the electrode and the workpiece. And increase the dispersion of metal vapor and metal melt. In addition, the machining liquid rapidly cools and solidifies machining scraps generated and scattered from the electrode and the workpiece by electric discharge,
The particles are prevented from adhering to the electrode / workpiece, the movement of the machining waste is facilitated, the discharge is generated, the movement of the discharge point is promoted, and the discharge gap length is increased. In addition, depending on the cooling action and the combination of the working fluid used, the electrode, and the work piece, pyrographite produced by decomposition of the working fluid is attached to the working surface of the electrode to prevent or reduce the consumption of the electrode.
Then, mainly during the discharge pause period between voltage pulses, the liquid flow discharges some or more of processing dust, tar, gas, etc., caused by processing and decomposition, to the outside of the discharge gap, and based on the application of the next voltage pulse. The discharge generated in the gap is made normal, and the intended machining action is continued.

【０００４】然るに、本発明者等は、 １９９２年度精密工学会春季大会学術講演会（平成４
年３月２５日、講演論文集 Ｐ２８１参照、以下文献１
と言う）に於て、「Ｈ２１ 極間における加工液流が放
電加工特性及び放電柱に与える影響」と言う表題の下
に、大気中で放電間隙に空気流を流して鋼対鋼の正極性
加工で低消耗加工が行えることを報告し、次いで本発明
者は、 電気加工学会全国大会（１９９４）（１９９４年１０
月１８日、講演論文集Ｐ３５参照、以下文献２と言う）
に於て、「［１１］単発放電における加工屑の分散の観
察」と言う表題の下に、単発放電において気中では加工
屑が工作物に再付着すること、パルス幅が１００μＳ
（マイクロ秒）以上で生じる加工屑体積が液中放電の場
合とあまり差が見られなくなること、故に気中加工であ
っても加工屑を放電間隙外へ排出さえすれば、通常の液
中加工と同様に加工が行える可能性があることを報告
し、そして、 １９９５年度精密工学会春季大会学術講演会（平成３
年３月２８日、講演論文集Ｐ９５７参照、以下文献３と
言う）に於て、「Ｇ６２ 気中と液中の放電加工特性の
違い」と言う表題の下に、気中放電加工は、正極性加工
でパルス幅の如何に関らず工具電極の消耗が見られな
い、電極の肉厚が薄いほど加工量が増加する、そして短
絡が液中加工に比べて多いこと、及び短絡の防止には電
極に回転や搖動を付加させると有効であること等を報告
した。Therefore, the inventors of the present invention have been invited to the 1992 Precision Engineering Society Spring Conference Academic Lecture Meeting (1992).
March 25, 2013, See P281
Under the heading "Effect of machining fluid flow between H21 electrodes on EDM characteristics and electric discharge column", the positive polarity of steel to steel It was reported that low consumption machining can be performed by machining, and the present inventor then announced that the Electrical Processing Society of Japan National Convention (1994) (1994
(Refer to P. 35 of the lecture papers on May 18th, referred to as Reference 2 below)
Under the heading "[11] Observation of dispersion of machining chips in single-shot discharge", re-attachment of work chips to the workpiece in the air in single-shot discharge, pulse width of 100 μS
The volume of machining waste generated for (microseconds) or more does not differ much from the case of in-liquid discharge, so even in air machining, as long as the machining waste is discharged outside the discharge gap, normal liquid machining It has been reported that there is a possibility that processing can be performed in the same manner as in the above, and the 1995 Japan Society for Precision Engineering Spring Conference Academic Lecture (1993).
In the collection of lecture papers, P957, March 28, 2013, referred to as Reference 3 below), under the heading "G62: Difference in electrical discharge machining characteristics in air and liquid," The wear of the tool electrode is not seen regardless of the pulse width in the flexible machining, the machining amount increases as the thickness of the electrode is thinner, and the short circuit is more frequent than the submerged machining, and it prevents the short circuit. Reported that it is effective to add rotation and oscillation to the electrode.

【０００５】以上の文献１〜文献３の如き研究開発の結
果は、それ等文献に於て言うところの気中放電加工を、
従来よりの液中放電加工の一部等に替えて産業上利用す
ることができる技術及び製品等として登場させるには、
未だ種々の問題があった。The results of the research and development as described in Documents 1 to 3 above are the results of the air discharge machining as referred to in those documents.
In order to replace it with a part of the conventional submerged electrical discharge machining and to introduce it as technology and products that can be industrially used,
There were still various problems.

【０００６】而して、従来気中放電加工と言えるものと
しては、特公昭４６−４３，７６０号公報及び同４７−
３，０７８号公報に記載のような、不銹鋼製の紡糸口金
オリフィスの加工を、少なくとも２１％、好ましくは少
なくとも３５％の有効酸素を含むガス流を火花放電の区
域内に連続的に指向させた気体中のワイヤ放電加工によ
り、正極性接続の直流電源により、又は７００Ｈｚ以下
の交流電源によりタングステンワイヤ電極と口金間で放
電させて加工するもの、或いは、特公昭５２−１１，０
７３号公報や同５７−４，４５１号公報等に記載されて
いる、大気圧以下に減圧された雰囲気中において電極と
被加工体とを対向させ、両者間でパルス放電を行なわせ
るもの、或いは更に加工液噴霧気流中でワイヤ放電加工
を行なうもの（特公昭５７−４，４５１号公報）、加工
液中に浸漬配置した放電間隙に気体を流通介在せしめな
がら放電加工するもの（特公昭３９−１，４９４号公
報、同４０−２７，４２５号公報）、及び気体を気泡状
に混合した加工液を放電間隙に流通介在させながら放電
加工するもの（特公昭３９−２９，６１５号公報）等も
あったが、何れも今日、なお、実用化されるには到って
いないようである。[0006] Thus, the conventional air discharge machining is disclosed in Japanese Patent Publication Nos. 46-43, 760 and 47-.
Processing stainless steel spinneret orifices, such as those described in US Pat. No. 3,078, was conducted by continuously directing a gas stream containing at least 21%, preferably at least 35% of available oxygen into the area of the spark discharge. Machined by wire electrical discharge machining in gas, by a direct current power supply with positive polarity connection, or by an alternating current power supply of 700 Hz or less to discharge between a tungsten wire electrode and a base, or Japanese Patent Publication No. 52-11,0
No. 73, No. 57-4,451, etc., in which an electrode and a workpiece are opposed to each other in an atmosphere depressurized to atmospheric pressure or less, and pulse discharge is performed between the electrodes, or Further, wire electric discharge machining is performed in a machining liquid spray airflow (Japanese Patent Publication No. 57-4,451), and electric discharge machining is performed while gas is allowed to flow through a discharge gap immersed in the machining liquid (Japanese Patent Publication No. 39-39-39). No. 1,494, No. 40-27,425), and a method in which electric discharge machining is performed while a machining fluid in which gas is mixed in a bubble state is circulated through an electric discharge gap (Japanese Patent Publication No. 39-29,615). However, none of them seems to be in practical use today.

【０００７】そこで本発明者は、更に研究開発を続けた
結果、 電気加工学会全国大会（１９９５）（１９９５年１１
月１日、講演論文集Ｐ１２９参照、以下文献４と言う）
に於て、「［２２］気中放電加工の加工速度向上に関す
る研究」と言う表題の下に、上記文献３で報告したよう
な気中放電加工に於ては、 「ｉ）供給空気圧力には最適値が存在する。供給空気圧
力が高すぎると極間の空気量が過大になり、アーク柱が
工作物上を滑ることによって加工速度が低下する。ま
た、供給空気圧力が低過ぎる場合は、加工屑の排出が困
難となり短絡率が上昇し、さらに、加工屑が工作物に付
着する割合が増えるため加工速度が減少する。 ii）高（電）圧重量の印加によって広い極間での加工が
可能となり、有効放電頻度が増加し加工速度向上に効果
がある。 iii)気中加工でも工具軌跡を工夫することによって、３
次元形状創成加工が（電極）無消耗で行うことができ
る。」ことを、又 １９９５年度精密工学会秋季大会学術講演会（平成７
年９月２９日、講演論文集 Ｐ３１１参照、以下文献５
と言う）に於て、「Ｋ０２ 気中放電加工における電極
無消耗のメカニズム」と言う表題の下に、「気中におけ
る工具電極無消耗の要因を実験および熱伝導解析により
調べた結果… ｉ）工具電極材料の銅は放電直後に２μｍ加工された後
加工が進行せず、工作物材料の鋼は加工直後から工具電
極に付着し、１分以内で付着層厚さ８．５μｍ程度で一
定になる。 ii）鋼の付着が銅工具電極の溶融状態に与える影響は大
きく、３μｍ以上の付着があれば、それ以後は工具電極
の銅部は全く除去されない。 iii)工具電極に付着する工作物付着層厚さの時間変化シ
ミュレーションを行なったところ実験結果と定性的に一
致した。」ことを報告した。Therefore, the present inventor further researched and developed, and as a result, the National Convention of Electrical Processing (1995) (November 1995)
(Refer to P129 on the 1st of the month, P129, referred to as Reference 4 below)
Under the heading "[22] Study on improvement of machining speed in air electric discharge machining", in air electric discharge machining as reported in the above-mentioned reference 3, "i) supply air pressure If the supply air pressure is too high, the air volume between the poles will be too large and the machining speed will be reduced due to the arc column sliding on the work piece, and if the supply air pressure is too low, , It becomes difficult to discharge the machining waste, the short-circuit rate increases, and the machining speed decreases because the ratio of the machining waste adhering to the workpiece increases. Ii) The application of high (electric) pressure weight causes a wide gap between the electrodes. Machining becomes possible, effective discharge frequency increases, and it is effective in improving machining speed.iii) Even in mid-air machining, by devising the tool path, 3
It is possible to perform the three-dimensional shape creation processing without (electrode) consumption. In addition, the 1995 Japan Society for Precision Engineering Autumn Meeting Academic Lecture Meeting (1995
September 29, 2013, See P311, Proceedings, below 5
Under the heading "K02 Mechanism of electrode wear-out in air electric discharge machining", "Results of investigating factors of tool electrode wear-out in air by experiments and heat conduction analysis ... i) Copper of the tool electrode material is machined to 2 μm immediately after the electric discharge, and the machining does not proceed. Steel of the workpiece material adheres to the tool electrode immediately after machining, and the adhesion layer thickness is about 8.5 μm within 1 minute. Ii) The influence of the adhesion of steel on the molten state of the copper tool electrode is large, and if the adhesion is 3 μm or more, the copper part of the tool electrode is not removed at all thereafter. Iii) Workpiece adhered to the tool electrode When the time-varying simulation of the adhesion layer thickness was performed, it was qualitatively consistent with the experimental result. "

【０００８】[0008]

【発明が解決しようとする課題】そして、本発明者はそ
の後もなお研究開発を継続した結果、一つの実用可能と
思われる気中放電加工の方法及び装置をほぼ完成させる
に到ったことにより本発明を提案するに至ったものであ
る。即ち、現用の加工液として鉱油系の加工液を使用す
るラム型放電加工機の主として仕上げ加工域での電極消
耗と加工速度問題、及び斯種放電加工機の消防法及び危
険物に関する政令と規則に関する問題を解決せんとする
ものである。As a result of continuing research and development after that, the present inventor has almost completed one method and apparatus for air electric discharge machining which seems to be practical. The present invention has been proposed. That is, the electrode consumption and machining speed problem mainly in the finishing machining area of the ram type electric discharge machine which uses the mineral oil type machining fluid as the current machining fluid, and the fire decree of this kind of electric discharge machine and the government ordinance and rules concerning dangerous materials. The problem is to solve.

【０００９】放電加工の（以下、特別の断り書きのない
限り、「放電加工」と言うと、鉱油系加工液を使用する
穿孔、型彫加工用のラム型放電加工機を指すものとす
る。）１放電パルス当りの放電エネルギが小さく、加工
面粗度の小さい仕上げ加工条件の加工領域での加工の際
には、加工性能上、加工電極を負極とする所謂正極性加
工が多く用いられるが、電極消耗が多く、単一加工電極
では並進運動（又は搖動運動）加工等複雑で時間を要す
る加工操作等を採用したとしても形状精度が出にくいと
言う問題があった。また、上記仕上げ加工条件の加工領
域での加工速度が遅く、長時間を要することに甘受して
いた節があるが、他の加工手法のもの等と比較する迄も
なく、加工速度の向上が望まれていたものである。[0009] In electrical discharge machining (hereinafter, unless otherwise specified, "electrical discharge machining" refers to a ram type electrical discharge machine for drilling and die cutting using a mineral oil-based machining liquid. ) When machining in a machining area where the discharge energy per discharge pulse is small and the machining surface roughness is small, so-called positive polarity machining in which the machining electrode is the negative electrode is often used in terms of machining performance. However, there is a problem in that the shape is difficult to obtain even if a complicated and time-consuming machining operation such as translational (or swinging) machining is adopted with a single machining electrode. Also, there is a section that the processing speed in the processing area of the finishing processing conditions is slow and it takes a long time, but there is no need to compare with other processing methods, etc., and the processing speed can be improved. It was what was desired.

【００１０】現用の放電加工装置（ラム型及びワイヤ型
の両方）については、既に少し述べたところであるが、
前記装置は、概して、放電加工機本体と、加工用電源装
置及び制御装置と加工液の循環処理供給装置の３つの部
分から成り、この３つの内で加工液関係の装置が最も安
価であるものの加工液の使用は放電加工装置の設置及び
使用に種々の問題や不具合を生じさせていた。加工液の
循環処理供給装置は、周知のように清浄槽や汚濁槽等の
加工液貯槽、加工屑等を除去する濾過装置、１個以上の
循環、汲み上げ等のポンプ、クーラ等加工液の温度制御
装置、配管及び切換、制御弁、そして加工液が鉱油系の
場合には防災のための検知及び消火装置、水系加工液の
場合にはイオン交換とその制御装置及び添加有機物等の
供給及び処理装置等より成り、可成りの床面積を要する
高価格のものであり、保守、管理等にも相当の手間を要
するものである。而して、加工槽へ浄化等により循環供
給し加工部加工間隙に適当な加工屑濃度を保って流通介
在させられる稼動時の加工液供給制御等は、高度に自動
化されているものの、通常鉱油系加工液が使用されるラ
ム型放電加工機は、その加工液の使用及び貯蔵量等にも
よるが、消防法及び危険物に関する政令と規則等によ
り、設置地域とか設置及び取扱いの規制が順次強化され
る傾向にあるものである。Regarding the current electric discharge machine (both the ram type and the wire type), as already mentioned,
The apparatus is generally composed of an electric discharge machine main body, a machining power supply device and a control device, and a machining liquid circulating treatment supply device. Of these three parts, a machining liquid-related device is the cheapest. The use of the working fluid has caused various problems and problems in the installation and use of the electric discharge machine. As is well known, the processing liquid circulation processing supply device is a processing liquid storage tank such as a cleaning tank or a pollution tank, a filtering device for removing processing waste, one or more circulation, pumps such as pumping, a temperature of the processing liquid such as a cooler. Control device, piping and switching, control valve, detection and fire extinguishing device for disaster prevention when the working liquid is mineral oil, ion exchange and control device and supply and treatment of added organic matter when water-based working liquid It is a high-priced product that is made up of devices and the like and requires a considerable amount of floor space, and requires a considerable amount of labor for maintenance and management. Therefore, although the supply of the working fluid during operation, in which it is circulated and supplied to the processing tank by purification or the like, and is circulated through while maintaining an appropriate processing waste concentration in the processing gap of the processing portion, is usually mineral oil. Lamb-type electric discharge machines that use a system-based machining fluid are subject to installation areas and regulations for installation and handling in accordance with the Fire Service Act and governmental regulations and regulations regarding dangerous materials, depending on the amount of machining fluid used and the amount of storage. It tends to be strengthened.

【００１１】[0011]

【課題を解決するための手段】前述の本発明の目的は、
（１）加工電極と被加工体とを微細な加工間隙を隔てて
相対向させると共に対向方向に相対的に近接開離の加工
送り及び送り位置決め制御可能に設け、前記加工間隙に
加工媒体を流通介在させた状態で前記電極、被加工体間
に直流電圧源を電子スイッチ素子をオン・オフ制御する
ことにより生成する休止時間を置いた間歇的な電圧パル
スを繰り返し印加し、発生する放電により被加工体を加
工する放電加工方法に於て、前記加工電極の被加工体と
の相対向加工面が、大凡０．０５〜３ｍｍの薄肉幅でこ
の幅方向と交叉する方向に前記幅以上の長さにわたって
延在し、被加工体の加工領域の被加工面、又は該被加工
面の一部と相対向し得る加工面から成り、該加工電極の
前記加工面のほぼ全面にわたって被加工体の被加工面と
の間にほぼ均一な前記の微細な加工間隙を形成させた状
態として、該加工間隙に被加工体材と化学反応をする気
体を含有する加圧気体を加工媒体として大凡前記幅方向
に強制的に流通するように噴射させて介在させた状態に
すると共に、前記電極・被加工体間のほぼ対向方向の軸
の廻りの相対的な回転及び前記対向方向の軸に対してほ
ぼ直角方向の微細ストロークの相対的な並進運動の両方
又は何れか一方を付与させた状態とし、前記印加電圧パ
ルスによる放電を行なわせつつ前記対向方向の加工送り
による穿孔加工、又は前記対向方向の所定の切込み量位
置での被加工体の加工領域に対する電極加工面の対向部
位を順次に移動させて加工する気中放電加工方法、とす
ることにより、又、（２）前記（１）の気中放電加工方
法に於て、被加工体材と化学反応をする気体を酸素とす
ることにより、又、（３）前記（１）の気中放電加工方
法に於て、被加工体材と化学反応をする気体を含有する
加圧気体を、圧縮空気、好ましくは空気よりも酸素リッ
チな圧縮気体、又は圧縮酸素とすることにより、又、
（４）前記（１），（２），又は（３）に記載の気中放
電加工方法に於て、前記加圧気体が前記加工間隙に少な
くとも０．０５ＭＰａ以上、１．０ＭＰａ以下の圧力で
供給された状態とすることにより、又、（５）前記
（１），（２），（３）、又は（４）に記載の気中放電
加工方法に於て、前記加圧気体を、前記加工間隙に２０
ｍ／ｓ乃至２５０ｍ／ｓ、好ましくは５０ｍ／ｓ乃至２
００ｍ／ｓの流速で流通介在させた状態とすることによ
り、又、（６）前記（１），（２），（３），（４）、
又は（５）に記載の気中放電加工方法に於て、前記被加
工体材と化学反応をする気体が、当該設定加工条件下に
於ける平均放電電力によって加熱溶融、更には溶融飛散
させられる被加工体材の量に応じて供給量を制御するこ
とにより、又、（７）前記（１），（２），（３），
（４），（５）、又は（６）に記載の気中放電加工方法
に於て、前記被加工体が鉄を主成分とする鉄系合金で、
前記加工電極が銅又は銅を主成分とする銅系合金の電
極、被加工体材の組合せ加工とすることにより、又、
（８）前記（１），（２），（３），（４），（５），
（６）、又は（７）に記載の気中放電加工方法に於て、
前記加工電極を、薄肉厚幅の筒状体又は円筒状体の棒状
電極とすることにより、又、（９）前記（１），
（２），（３），（４），（５），（６），（７）、又
は（８）に記載の気中放電加工方法に於て、前記加工電
極と被加工体間に休止時間を置いて印加される間歇的な
加圧電圧パルスが、加工電極を負極とする正極性として
印加放電加工するように構成することにより、又、（1
0）前記（１），（２），（３），（４），（５），
（６），（７），（８）、又は（９）に記載の気中放電
加工方法に於て、前記加工電極と被加工体間に休止時間
を置いて供給される放電電力が、無負荷電圧が１００Ｖ
前後の電圧が低くて放電電流の大きい主加工用パルス電
源と、無負荷電圧が２００Ｖ以上の高電圧で電流容量が
小さい少なくとも１つの補助パルス電源との並設により
供給される構成とすることにより、より良く達成される
ものである。SUMMARY OF THE INVENTION The above-mentioned object of the present invention is as follows.
(1) The machining electrode and the object to be machined are opposed to each other with a minute machining gap therebetween, and the machining feed and the feed positioning can be controlled so that the machining gap is relatively close in the opposing direction, and the machining medium is circulated in the machining gap. Intermittent voltage pulses are repeatedly applied between the electrodes and the object to be processed by turning on and off the electronic switch element by controlling the DC voltage source between the electrodes, and the intermittent voltage pulse is repeatedly applied to generate a discharge by the generated discharge. In an electric discharge machining method for machining a machined body, a machining surface of the machining electrode facing the body to be machined has a thin wall width of approximately 0.05 to 3 mm and a length greater than the width in a direction intersecting with the width direction. A machining surface that extends over the entire length of the machining electrode, or a machining surface that can oppose a part of the machining surface of the machining area of the machining object. Almost uniform with the work surface With the above-described fine machining gap formed, a pressurized gas containing a gas that chemically reacts with the workpiece material is injected into the machining gap as a machining medium so that it is forcedly circulated in the width direction. And intervene, and the relative rotation between the electrode and the work piece about the axis in the substantially opposite direction and the relative translation of the fine stroke in a direction substantially perpendicular to the axis in the opposite direction. Both or any one of the movements is applied, and the punching is performed by the machining feed in the facing direction while the discharge is performed by the applied voltage pulse, or the workpiece at a predetermined cut amount position in the facing direction. In the air-electric discharge machining method according to (2), the work piece is processed by providing an air-electric discharge machining method in which the facing portion of the electrode machining surface with respect to the machining area is sequentially moved for machining. Chemical reaction with wood By using oxygen as the gas, or (3) in the method of the electric discharge machining in the above (1), the pressurized gas containing the gas that chemically reacts with the workpiece is compressed air, preferably compressed air. Is compressed gas that is richer in oxygen than air, or compressed oxygen.
(4) In the air-electric discharge machining method described in (1), (2), or (3), the pressurized gas is applied to the machining gap at a pressure of at least 0.05 MPa and 1.0 MPa or less. By supplying the pressurized gas, in the air discharge machining method according to (5), (1), (2), (3), or (4), 20 in the processing gap
m / s to 250 m / s, preferably 50 m / s to 2
In addition, by making the medium flow through at a flow velocity of 00 m / s, (6) above (1), (2), (3), (4),
Alternatively, in the air-electric discharge machining method according to (5), the gas that chemically reacts with the workpiece material is heated and melted by the average discharge power under the set machining conditions, and further melted and scattered. By controlling the supply amount according to the amount of the work material, (7) the above (1), (2), (3),
In the air-electric discharge machining method according to (4), (5), or (6), the workpiece is an iron-based alloy containing iron as a main component,
The processing electrode is a copper-based or copper-based alloy electrode containing copper as a main component, and is a combination processing of workpiece materials,
(8) The above (1), (2), (3), (4), (5),
In the air electric discharge machining method according to (6) or (7),
By making the processing electrode a rod-shaped electrode having a thin wall thickness or a cylindrical body or a cylindrical body, (9) the above (1),
In the air electric discharge machining method according to (2), (3), (4), (5), (6), (7), or (8), a pause between the machining electrode and the workpiece. The intermittent pressurizing voltage pulse applied at a certain time is configured so as to perform the electric discharge machining as the positive polarity with the working electrode as the negative electrode.
0) The above (1), (2), (3), (4), (5),
In the air electric discharge machining method described in (6), (7), (8), or (9), the electric discharge power supplied with a pause between the machining electrode and the workpiece is Load voltage is 100V
By providing the main processing pulse power source having a low front and rear voltage and a large discharge current and at least one auxiliary pulse power source having a high no-load voltage of 200 V or more and a small current capacity, the power is supplied in parallel. , Better achieved.

【００１２】[0012]

【作用】請求項１記載の発明による気中放電加工方法に
よれば、被加工体材と化学反応をする気体を含有する加
圧気体の制御供給装置を必要とするものの、加工液及び
その循環処理供給装置を必要としない気中放電加工なる
ものを、或る程度の幅の荒、中、仕上げの加工領域にわ
たって、或る程度以上の加工速度で、安定した状態で、
継続して加工を続けることが出来るようになり、被加工
体にその表面加工及び所望キャビティの加工、更には或
る程度の深さの穿孔加工を確実に反復して行なえるよう
になった。請求項２記載の発明による気中放電加工方法
によれば前記請求項１に記載の気中放電加工の加工速度
を格段に向上させることができるようになった。請求項
３記載の発明による気中放電加工方法によれば、前記請
求項１に記載の気中放電加工の加工速度を格段に向上さ
せた状態として確実に加工を継続させることができる。
請求項４記載の発明による気中放電加工方法によれば、
前記請求項３までに記載の気中放電加工を好適な加工条
件下で確実に行なえるようになる。請求項５記載の発明
による気中放電加工方法によれば、前記請求項４までに
記載の気中放電加工をより良い加工条件下で行なうこと
ができるようになる。請求項６記載の発明による気中放
電加工方法によれば、前記請求項５までに記載の気中放
電加工をより良い加工状態での加工が行なえるようにな
る。請求項７記載の発明による気中放電加工方法によれ
ば、前記請求項６までに記載の気中放電加工を、銅又は
銅合金製の加工電極を使用した鉄材金型等の加工として
実用に供することができるようになる。請求項８記載の
発明による気中放電加工方法によれば、前記請求項７ま
でに記載の気中放電加工を被加工体の穿孔加工、及び表
面加工又は順次走査の創成加工による所望キャビティ加
工等を確実に継続した加工として加工できるようにな
る。請求項９記載の発明による気中放電加工方法によれ
ば、前記請求項８までに記載の気中放電加工を仕上げ加
工の加工条件領に於ても電極無消耗乃至は低消耗での加
工が確実に行なえるようになる。請求項１０記載の発明
による気中放電加工方法によれば、前記請求項９までに
記載の気中放電加工を加工間隙を広めて、短絡放電少な
く、有効放電の発生により、より安定した状態での加工
を可能とし、目的通り確実に加工を終了させることがで
きる。According to the air-electric discharge machining method of the first aspect of the present invention, a machining fluid and its circulation are required, though a control and supply device for a pressurized gas containing a gas that chemically reacts with a workpiece is required. Air-electric discharge machining that does not require a processing and feeding device can be performed in a stable state at a machining speed of a certain level or more over a certain width of rough, medium, and finishing machining areas.
It becomes possible to continue the processing, and it becomes possible to reliably and repeatedly perform the surface processing and the desired cavity processing on the object to be processed, and the boring processing to a certain depth. According to the air electric discharge machining method of the second aspect of the present invention, the machining speed of the air electric discharge machining according to the first aspect can be remarkably improved. According to the air-electric discharge machining method of the third aspect of the present invention, the machining speed of the air-electric discharge machining according to the first aspect can be reliably improved and the machining can be reliably continued.
According to the air-electric discharge machining method of the invention of claim 4,
In this way, the electric discharge machining according to claim 3 can be reliably performed under suitable machining conditions. According to the aerial electric discharge machining method of the fifth aspect of the present invention, the aerial electric discharge machining according to the fourth aspect can be performed under better machining conditions. According to the air electric discharge machining method of the sixth aspect of the present invention, the air electric discharge machining according to the fifth aspect can be performed in a better machining state. According to the air electric discharge machining method according to the invention of claim 7, the air electric discharge machining according to claim 6 is put into practical use as machining of an iron material mold or the like using a machining electrode made of copper or a copper alloy. You will be able to serve. According to the air electric discharge machining method according to the invention of claim 8, the air electric discharge machining according to claim 7 is applied to punching of a workpiece, and desired cavity machining such as surface machining or progressive scanning generation machining. Can be reliably processed as continuous processing. According to the air-discharge processing method according to the invention of claim 9, the air-discharge processing according to claim 8 can be performed without electrode wear or low wear even in the processing conditions of finishing. You will definitely be able to do it. According to the air electric discharge machining method according to the invention of claim 10, the air electric discharge machining according to claim 9 is performed in a more stable state by widening the machining gap, reducing short circuit discharge, and generating effective discharge. The processing can be performed, and the processing can be surely completed as intended.

【００１３】[0013]

【発明の実施の形態】図１は、本発明の気中放電加工方
法を実施する一実施例の全体構成説明図で、１は筒状加
工電極、２は電極チャック、３はスピンドル主軸を介し
て電極１を中心軸又は所望偏倚軸の廻りに回転させる回
転装置、４は加工ヘッド、５は送りネジ、６は加工ヘッ
ドの加工送り及び位置決め用の直流又は交流サーボモー
タ、７は該サーボモータ６による電極１先端の送り位置
（現在位置）を検出して検出信号を後述ＣＮＣ制御装置
に供給するエンコーダ等の送り又は現在位置等の送り位
置検出装置、８は前記サーボモータ６の回転速度を検出
して検出信号をＣＮＣ制御装置に供給する指速発電機や
エンコーダ等の回転速度検出装置、９は被加工体、１０
は被加工体９を設置する加工テーブル、１１は加工テー
ブルが載置されたｘｙクロステーブル、１２及び１３は
クロステーブル１１を介し加工テーブル１０をｘｙ各軸
方向に加工送り及び位置決め送りする前記位置検出及び
回転速度検出装置の図示が省略されたｘｙ各軸の加工送
り及び位置決めサーボモータ、１４は前記各サーボモー
タ６，１２、及び１３の駆動装置、１５は放電加工用の
ＣＮＣ制御装置で、１５Ａはコンピュータ、１５Ｂはキ
ーボード等の入力装置、１５Ｃは紙テープ、磁気テー
プ、フロッピィディスク、又はコンパクトディスク等の
放電加工用のデータやプログラム等の外部記憶装置、１
５Ｄは数値制御装置、１６は加工電極１と被加工体９間
に間歇的な電圧パルスを供給する放電加工用パルス電源
で、１７は直流電圧源、１８はＦＥＴ等のオン・オフ電
子スイッチ素子、１９は前記スイッチ素子１８及び電圧
源１７と直列に接続され放電パルスの電流振幅をＦＥＴ
の並列接続数と共に切換設定される電流制限抵抗、２０
は前記電子スイッチ素子１８のオン時間τON及びオフ時
間τOFF 等をＣＮＣ制御装置１５からの信号で選択切換
設定する電圧パルス条件設定装置、２１は逆電圧防止ダ
イオード、２２は電極１・被加工体９間の加工間隙の放
電加工状態検出装置、２３はエアコンプレッサ又は圧縮
若しくは液化気体ボンベまたはそれらの組合せから成
り、被加工体材と化学反応をする気体を含有する圧縮気
体供給装置、２４は必要に応じて設けられる水蒸気除去
のエア・ドライヤ、２５は供給圧縮気体の減圧調整弁で
ある。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an explanatory view of the overall configuration of an embodiment for carrying out the air discharge machining method of the present invention, in which 1 is a cylindrical machining electrode, 2 is an electrode chuck, and 3 is a spindle main shaft. Rotating device for rotating the electrode 1 around a central axis or a desired bias axis, 4 is a machining head, 5 is a feed screw, 6 is a DC or AC servomotor for machining feed and positioning of the machining head, and 7 is the servomotor. 6, a feed position (current position) of the tip of the electrode 1 is detected, and a detection signal is supplied to a CNC control device which will be described later. A rotation speed detecting device such as a finger speed generator or an encoder for detecting and supplying a detection signal to the CNC control device, 9 is a workpiece, 10
Is a machining table on which the workpiece 9 is installed, 11 is an xy cross table on which the machining table is placed, and 12 and 13 are positions for feeding and positioning the machining table 10 through the cross table 11 in the xy axial directions. Machining feed and positioning servomotors for xy axes (not shown) of the detection and rotation speed detection device, 14 is a drive device for each of the servomotors 6, 12 and 13, and 15 is a CNC control device for electric discharge machining. Reference numeral 15A is a computer, 15B is an input device such as a keyboard, 15C is an external storage device such as a paper tape, a magnetic tape, a floppy disk, or a compact disk for electric discharge machining data and programs.
5D is a numerical controller, 16 is a pulse power source for electric discharge machining which supplies intermittent voltage pulses between the machining electrode 1 and the workpiece 9, 17 is a DC voltage source, 18 is an ON / OFF electronic switch element such as FET. , 19 are connected in series with the switching element 18 and the voltage source 17, and are used to detect the current amplitude of the discharge pulse by the FET.
A current limiting resistor that is switched and set with the number of parallel connections of
Is a voltage pulse condition setting device for selectively switching the ON time τON and the OFF time τOFF of the electronic switch element 18 with a signal from the CNC controller 15, 21 is a reverse voltage prevention diode, 22 is the electrode 1 / workpiece 9 A device for detecting an electric discharge machining state of a machining gap between them, 23 is an air compressor or a compressed or liquefied gas cylinder or a combination thereof, and a compressed gas supply device containing a gas that chemically reacts with a workpiece material, and 24 is required. An air dryer for removing water vapor, which is provided accordingly, 25 is a decompression adjusting valve for the compressed compressed gas.

【００１４】図２は、図１放電加工機部の拡大側面図
で、図１のものに圧縮気体の流量計兼流量調整装置２
６、被加工体９加工部の加工屑を飛散除去又は吸引回収
する加工屑処理ノズル２８、及びｘｙクロスデーブル１
１を設置する基台２７等を付加図示したものである。FIG. 2 is an enlarged side view of the electric discharge machine section shown in FIG. 1, and is similar to that shown in FIG.
6, a processing waste processing nozzle 28 that scatters or removes the processing waste of the processed part 9 of the workpiece, and an xy cross table 1
1 is a diagram in which a base 27 for installing 1 and the like are additionally illustrated.

【００１５】図３のＡ乃至Ｉは筒状加工電極１の筒形状
の種類の例を示す電極先端正面図で、Ａは円筒状電極、
Ｂは多角形状電極、Ｃは長方形状電極、Ｄは三角形状電
極、Ｅは偏平長方形電極で一辺部分１Ａが絶縁体から構
成されている場合で必要に応じ機械的強度保持のために
筒口内に径方向に交叉するリブを設けることができる。
又Ｆは円筒状電極で所定円弧間隔毎に所定円弧長さの部
分が絶縁体から構成されている場合で、之等は中心軸の
廻りの回転及び微小半径の並進（揺動）運動両方向又は
何れか一方を与えた状体での被加工体の表面加工又は順
次走査創成加工には適用可能なものの、穿孔又は穴堀り
加工には、Ｅの筒状電極を除き筒状電極内に被加工体の
加工残り中子が存在し、加工の継続が困難となる場合が
あるので、穿孔等の加工の場合には、例えば、偏平長方
形状Ｇ、半円形状Ｈ、及び長楕円形状Ｉの如き筒状電極
を用い、図示ｘ印を中心として回転させるようにすれば
良い。そして加工電極１の軸方向先端部分の加工面は、
被加工体９の被加工領域部分の通常一部と、稀れに大部
分と、相対向し得る外形寸法及び形状を有していると共
に、該加工面は局部的に見ると薄肉厚幅の加工面が、該
幅方向と交叉する方向に前記幅の数倍以上の長さにわた
って延在するように形成されていることになり、図示の
如くチャック部３等から電極筒内に送り込まれた加圧気
体は、被加工体９の加工領域の一部の被加工面と、全体
的にほぼ均一な微細間隙を形成するように配置制御され
る電極加工面との間隙から、大凡前記加工面の前記幅方
向に強制的に流通するように噴射され放電により生成さ
れる溶融加工屑を外部に排出清掃すると共に、外加工屑
や溶融部と化学反応をし、更に電圧パルス休止時間には
加工領域等を冷却することとなる。3A to 3I are front views of electrode tips showing examples of tubular shapes of the tubular machining electrode 1, wherein A is a cylindrical electrode.
B is a polygonal electrode, C is a rectangular electrode, D is a triangular electrode, E is a flat rectangular electrode, and one side portion 1A is made of an insulator. Ribs that intersect in the radial direction may be provided.
Further, F is a cylindrical electrode in the case where a portion having a predetermined arc length at predetermined arc intervals is made of an insulator, and the like, the rotation around the central axis and the translation (swing) movement of a small radius in both directions or Although it can be applied to the surface processing or the sequential scanning generation processing of the object to be processed in the state where either one of them is given, in the case of drilling or digging, the cylindrical electrode except for the cylindrical electrode E is processed. Since the unprocessed core of the processed body may be present and it may be difficult to continue the processing, in the case of processing such as perforation, for example, a flat rectangular shape G, a semicircular shape H, and an oblong shape I are used. Such a cylindrical electrode may be used and rotated about the x mark in the figure. The processing surface of the axial tip of the processing electrode 1 is
The work piece 9 has an outer shape and a shape that can face each other in a normal part of the work area 9 and rarely in most of the work area, and the work surface has a thin thickness width when viewed locally. The machined surface is formed so as to extend over a length that is several times the width or more in the direction intersecting the width direction, and is fed into the electrode cylinder from the chuck portion 3 or the like as shown in the drawing. The pressurized gas is approximately the above-mentioned processing surface from the gap between the processing surface of a part of the processing region of the processing object 9 and the electrode processing surface whose placement is controlled so as to form a substantially uniform fine gap as a whole. In the above-mentioned width direction, the molten machining scraps that are jetted so as to be forced to flow in the width direction and discharged and discharged are discharged and cleaned, and also chemically react with the external machining scraps and the melted portion. The area will be cooled.

【００１６】以上図１乃至図３を参照しつつ本発明気中
放電加工方法を説明すると、前述図３に示したように加
工面が薄肉厚幅の、そして好ましくは、加圧気体を加工
媒体として、主として放電パルスにより溶融さらには飛
散する加工屑等の生成物を加工間隙外へ排出するため、
及びその加圧気体中に一部以上所定の割合で含有させた
被加工体材と化学反応をする気体が被加工体の放電溶融
部及び溶融飛散する加工屑を酸化又は窒化等化学反応さ
せて加工量を増大させると共に加工屑等の電極・被加工
体への再溶着を減ずるように、前記加工媒体としての加
圧気体を前記幅方向に所定高速度で流通させられる通常
筒状体から成る加工電極１は、チャック２により把持さ
れて、Ｚ軸サーボモータ６によりサーボ加工送り、又は
位置決め送りされる加工ヘッド４に回転駆動装置３によ
って必要に応じて回転されるように取り付けられて、加
工テーブル１０に取付けられた被加工体９と相対向せし
められる。これに対し、被加工体９には、必要に応じ、
又は前記加工電極１に対する回転と共に半径が電極１の
肉厚程度又はそれ以内の並進運動又は搖動運動をｘ及び
ｙ軸サーボモータ１２，１３の駆動制御により与え得る
ように構成され、電極１の加工面は各部が全体的にほぼ
均一な微細間隙を被加工体９の被加工表面との間に形成
維持された状態を保つようにして圧縮気体供給装置２３
からの供給加圧気体を前記微細な加工間隙の各部から全
体的に均一に流通噴出し得る状態とし、穿孔加工のため
にＺ軸方向のサーボモータ６による加工制御送りをする
か、又はこの状態を被加工体９の加工領域に対する電極
加工面のｘｙ平面方向の対向部位のサーボモータ１２，
１３制御駆動による走査等の順次移動の如何にかかわら
ず維持させた状態として加工電極１と被加工体９間に印
加される間歇的な電圧パルスに基づいて発生する放電に
より気中放電加工を行なうものである。而して、本発明
の気中放電加工に用いる加工用パルス電源１６は、後述
するように或る種の補助電源を１つ又はそれ以上設ける
ことが好ましい場合があるものの、基本的には無負荷電
圧が約６０〜１２０Ｖ、即ち約１００Ｖ前後の必要に応
じて電圧の切換設定が可能な直流電圧源１７に、逆電圧
防止ダイオード２１と電流制限抵抗１９及びオン・オフ
電子スイッチ素子１８との直列回路の複数個を所望任意
数並列接続可能に構成し、これを加工間隙を介して直列
の閉回路に接続した通常の加工用パルス電源で、電圧パ
ルスのオン時間又は放電パルスの持続時間τONと電圧パ
ルス休止時間τOFF を設定する電圧パルス条件設定装置
２０と放電流振幅Ｉp を設定する電流制限抵抗切換装置
１９とを、ＣＮＣ制御装置１５に於ける入力装置１５Ｂ
からの入力加工指令や加工情報と、記憶装置１５Ｃから
の加工性能、加工条件及び加工プログラム作成用等の各
種の読み出しデータとにより演算したコンピュータ１５
Ａの加工条件設定指令出力により設定し、又さらにＮＣ
制御装置１５Ｄに被加工体９に加工すべき加工穴の寸法
形状、走査加工の軌跡及び電極１のＺ軸位置、送り込み
等の作動制御指令が与えられるようになっている。The air discharge machining method of the present invention will be described with reference to FIGS. 1 to 3 as described above. As shown in FIG. 3, the machined surface has a thin and thick width, and preferably, a pressurized gas is used as a machining medium. In order to discharge the products such as processing chips that are melted and scattered by the discharge pulse to the outside of the processing gap,
And a gas that chemically reacts with the workpiece material that is contained in the pressurized gas at a predetermined ratio in part or more by chemically reacting the discharge melting part of the workpiece and the processing dust that is melted and scattered, such as nitriding or nitriding. To increase the processing amount and reduce the re-welding of processing scraps to the electrode / workpiece, it is composed of a normal cylindrical body through which a pressurized gas as the processing medium is passed at a predetermined high speed in the width direction. The machining electrode 1 is attached to a machining head 4 which is gripped by a chuck 2 and is servo-mechanically fed by a Z-axis servomotor 6 or is positionally fed by a rotary drive device 3 so as to be rotated as necessary. The workpiece 9 attached to the table 10 is opposed to the workpiece 9. On the other hand, if necessary, the workpiece 9
Alternatively, the machining of the electrode 1 is configured so that a translational movement or a swinging movement whose radius is equal to or less than the wall thickness of the electrode 1 can be given by the drive control of the x and y axis servomotors 12 and 13 along with the rotation with respect to the machining electrode 1. As for the surface, the compressed gas supply device 23 is configured such that each part maintains a state in which a substantially uniform fine gap is formed and maintained between the surface and the work surface of the work body 9.
The pressurizing gas supplied from the above is set in a state in which it can be flown and jetted uniformly from each part of the fine processing gap, and the processing control feed is performed by the servo motor 6 in the Z-axis direction for drilling, or in this state. Is a servo motor 12, which is a portion of the electrode processing surface facing the processing area of the workpiece 9 in the xy plane direction,
13 In-air electrical discharge machining is performed by electric discharge generated based on intermittent voltage pulses applied between the machining electrode 1 and the workpiece 9 while maintaining the state regardless of sequential movement such as scanning by control drive. It is a thing. The machining pulse power supply 16 used in the air-electric discharge machining of the present invention may preferably be provided with one or more auxiliary power supplies of a certain type as described later, but is basically not provided. The reverse voltage prevention diode 21, the current limiting resistor 19 and the on / off electronic switch element 18 are connected to the DC voltage source 17 whose load voltage is about 60 to 120 V, that is, about 100 V, and which can be set to switch the voltage as required. With a normal machining pulse power supply, which is configured so that any desired number of series circuits can be connected in parallel and connected in series via a machining gap, the voltage pulse ON time or discharge pulse duration τON The voltage pulse condition setting device 20 for setting the voltage pulse pause time τ OFF and the current limiting resistance switching device 19 for setting the discharge current amplitude Ip are connected to the input device 15B in the CNC control device 15.
The computer 15 calculated based on the input machining command and machining information from the computer and various read data for machining performance, machining conditions and machining program creation from the storage device 15C.
Set by the processing condition setting command output of A, and NC
The control device 15D is provided with an operation control command such as the size and shape of a hole to be machined in the workpiece 9, the locus of scanning, the Z-axis position of the electrode 1, and the feed.

【００１７】以下に本発明の気中放電加工方法を実験例
により説明するが、下記の実験条件及び評価項目の定義
等は断り書きのない限り下記記載の通りのものとする。 加工電極 材質：銅 形状、寸法：外径φ８．６１ｍｍ、内径φ８．０ｍｍ 被加工体 材質：鋼 Ｓ４５Ｃ 加工量 ＝加工前被加工体重量−加工後被加工体重量（ｇ） 加工電極消耗量 ＝加工前加工電極重量−加工後加工電極重量（ｇ） 加工速度 ＝加工量／加工時間（ｇ／ｓｅｃ） 加工電極消耗率 ＝加工電極消耗量／加工量×１００（％） 放電１回当り加工量＝加工量／有効放電数（ｇ／発） 有効放電頻度 ＝有効放電数／加工時間（１／ｓｅｃ） 短絡率 ＝（総放電数−有効放電数）／総放電数×１００（％） 有効放電数とは、放電回路の電流センサ出力信号のある
なしと、検出放電電圧が或しきい値以上か否かとの論理
積を取る短絡検出回路を用い、検出放電電圧が５Ｖ以下
の放電パルスを短絡と看し、有効放電をカウンタで計数
した。又、加工の態様としては、上記円筒加工電極をＺ
軸方向に被加工体と相対向させ、加工電極に対する回転
（１８０ｒｐｍ）と、該加工電極に対する被加工体への
ｘｙ平面方向の並進運動又は搖動運動（半径：パイプ電
極肉厚の約１０％）の両方又は何れか一方を与えつつ、
加工電極のＺ軸の位置を固定した状態で被加工体をｙ軸
方向の所望のストローク長さ、ｘ及びｙ軸方向のサーボ
制御を行いつつ往復移動させるようにし、ｙ軸ストロー
クの両端に於て、加工電極を対向Ｚ軸方向に所定切込み
量被加工体表面に近接送り固定させるようにした。斯種
気中放電加工に於て、加圧気体が可成りの高速で流通す
る加工間隙の放電開始間隙長（ｇｓ：加工電極を被加工
体表面に向けて近接送りをして行った時最初に放電が発
生する極間長さ）は、約５μｍ／１００Ｖ程度又はそれ
以下位で、休止時間を置いて、例えばデューティファク
タ約７０％で設定加工条件の電圧パルスを印加している
気中放電加工中の平均加工間隙長（ｇｍ）は、設定加工
条件によって相違するが、上記放電開始間隙長よりも可
成り大きいものと思えるが、発生加工屑等が加工間隙の
加工媒体中に動きを拘束されると共に浮遊等して加工媒
体と共に加工間隙中に介在することになる加工液中加工
の平均加工間隙長に比べて可成り小さいようである。而
して、上記切込み量とは、加工電極を被加工体表面に近
接加工送りをし、電極先端加工面が大凡被加工体の加工
前の表面位置まで加工送りをして来て、その位置で或る
程度放電を継続させた時に、当該設定加工条件で放電加
工される加工深さ程度、又は加工深さよりも短い長さを
目途として、他方のｙ軸端に達して折り返すときにｚ軸
の切込み量の設定とするものである。Hereinafter, the air discharge machining method of the present invention will be described with reference to experimental examples. The following experimental conditions and evaluation items are defined as described below unless otherwise noted. Machining Electrode Material: Copper Shape, Dimension: Outer Diameter φ8.61 mm, Inner Diameter φ8.0 mm Workpiece Material: Steel S45C Machining Amount = Pre-machining Workpiece Weight-Post-working Object Weight (g) Machining Electrode Consumption ＝ Machining electrode weight before machining-Machining electrode weight after machining (g) Machining speed = Machining amount / Machining time (g / sec) Machining electrode consumption rate = Machining electrode consumption amount / Machining amount x 100 (%) Machining amount per discharge = Machining amount / effective discharge number (g / shot) Effective discharge frequency = Effective discharge number / Processing time (1 / sec) Short circuit rate = (Total discharge number-Effective discharge number) / Total discharge number x 100 (%) Effective discharge The number is a short-circuit detection circuit that takes the logical product of the presence or absence of the current sensor output signal of the discharge circuit and whether the detected discharge voltage is above a certain threshold value. The effective discharge was counted by the counter. As a processing mode, the above-mentioned cylindrical processing electrode is
Rotation (180 rpm) with respect to the work electrode in the axial direction opposite to the work piece, and translational motion or rocking motion in the xy plane direction with respect to the work piece with respect to the work electrode (radius: about 10% of pipe electrode wall thickness) While giving both or either of
With the Z-axis position of the machining electrode fixed, the workpiece is moved back and forth while performing the desired stroke length in the y-axis direction and servo control in the x- and y-axis directions, and at both ends of the y-axis stroke. Then, the processing electrode is fixed in proximity to the surface of the object to be processed by a predetermined cut amount in the opposite Z-axis direction. In such electrical discharge machining in the air, the discharge start gap length of the machining gap in which the pressurized gas circulates at a fairly high speed (gs: first when the machining electrode is fed close to the surface of the workpiece) Is about 5 μm / 100V or less, and there is a rest time, for example, a duty factor of about 70% and a voltage pulse of a set machining condition is applied to the air discharge. The average machining gap length (gm) during machining differs depending on the set machining conditions, but seems to be considerably larger than the above-mentioned discharge start gap length, but the generated machining debris restrains movement in the machining medium in the machining gap. It seems that it is considerably smaller than the average machining gap length of machining in the machining liquid which is suspended and floats and intervenes in the machining gap together with the machining medium. Thus, the above-mentioned depth of cut means that the machining electrode is fed to the surface of the work piece in the proximity of the work piece, and the machining surface of the electrode tip is roughly fed to the surface position of the work piece before the work piece is fed. When the electric discharge is continued for a certain amount, the z-axis is reached when reaching the other y-axis end and folding back, with the aim of the machining depth of the electric discharge machining under the set machining conditions or a length shorter than the machining depth. The depth of cut is set.

【００１８】被加工体材と化学反応をする加圧気体を用
いて気中放電加工することの有効性の確認のために、加
工媒体としての加圧気体としてアルゴン、窒素、空気、
及び酸素と放電加工液（ケロシン）中で、下記の条件で
放電加工を行ない図４及び図５の結果を得た。 実験加工条件 放電電流振幅Ｉp （Ａ） ２０ 無負荷電圧（Ｖ） ２８０ 印加加工電圧極性ＰＬ 正極性 放電パルス幅τON（μＳ） ２０、３５０、及び１０００ デューティファクタ（％） ７１ 搖動の半径（μｍ） ３０ 加圧気体供給圧力（ＭＰａ） ０．３ 切込み量（μｍ） ５（但し、τON：２０μＳ） １５（但し、τON：３５０、及び１０００μＳ ） 図４は、使用加圧気体の種類と加工条件の違いによる加
工速度の比較図で、パルス幅２０μＳ時のアルゴンガス
使用時の加工結果が無いのは、このパルス幅の設定加工
条件では加工が行なえなかったからである。そして図に
よれば、被加工体材（鉄：Ｆｅ）と化学反応をする気体
として酸素（Ｏ2 、なお、空気は約２１％の酸素と約７
８％窒素から成る）を供給した場合の加工速度が一番速
く、特にパルス幅２０μＳの仕上げ加工に近い領域では
液中加工の場合の約１０倍、空気の場合でも数倍以上に
なっているのに対し、不活性ガス（被加工体材と化学反
応をすることがない）アルゴンでは殆んど加工できない
ことが判る。これは、加工媒体の加圧気体が、酸素及び
２１％酸素の空気の場合は、放電により溶融した被加工
体材が、酸化反応によって爆発的に燃焼し、それによっ
て生じた反応熱が被加工体の溶融領域を更に拡大させる
ため加工速度が増大したものと考えられる。また、生じ
る加工屑が微細なほど同じ加工屑体積に対して表面積が
大きいので酸化等の供給気体との化学反応が促進される
と考えられ、本発明気中放電加工の仕上げ加工への適用
が有用なことが伺える。これに対し、窒素の場合は、被
加工体材の鉄と或る程度反応性を有し、かつ窒化物が高
硬度で耐摩耗性を有することから、表面処理加工等とし
ても期待されるところであるが、窒素と被加工体材鉄と
の化学反応は酸素の場合程激しくも反応熱の発生もな
く、溶融部の拡大が生ぜず、加工速度の増大が生じない
ものと考えられる。又、アルゴンの場合は、加工間隙の
被加工体面に再付着することなく外部へアルゴン気流に
よって吹き飛ばされた加工屑のみが加工量となるもので
あるが、上記の加工条件では、その量は何れの加工条件
でも極めて少ないと認められる。そして、以上のような
加工速度の傾向、状態は、上記の如き得られた加工デー
タから、放電１回当りの加工量を求めて照合した結果と
一致しており、本発明の気中放電加工方法の加工機構
は、加工間隙の溶融部分が放電衝撃及び高速流通の加圧
気体により吹き飛ばされることによるのみではなく、被
加工体の放電部分の被加工体材が供給加圧気体の一部以
上と化学反応していることが、加工結果に大きく影響し
ているものであることが判る。従って、本発明の気中放
電加工方法に於て、加工の能率を高めるには、被加工体
材と化学反応をする気体が、当該設定加工条件下に於け
る平均加工放電電力によって加熱溶融、更には溶融飛散
させられる被加工体材の量に応じた供給量に調整するの
が好ましいようで、このための手法としては供給加圧気
体中の被加工体材と化学反応をする気体の割合を、酸素
リッチ気体の如く増大させるか、アーク柱を移動等間隙
から滑らせない範囲で加圧気体の間隙流通流量又は流速
を増大させたりするものである。而して、前記加工条件
のパルス幅３５０μＳの時、放電電流振幅Ｉp を６０Ａ
にしたところ、アルゴンと窒素使用時の加工量増大は２
〜３倍、空気の場合は約２０％増、酸素の場合は約６０
％に減に対し、液中加工の場合は加工安定度が悪く約１
／８に減少した。図５は、上述の加工時の加工電極消耗
率の比較図で、このデータによれば、空気と酸素の場合
の加工電極の電極消耗率がパルス幅τONの大小の如何に
かかわらず非常に少なく、そして酸素は空気の場合より
も少なく、これに対して窒素及びアルゴンはパルス幅が
大きくなるに従って加工電極消耗率は増大し、しかもア
ルゴンの場合の増加率は高く、又前述放電電流振幅を６
０Ａに設定した場合には、窒素以外何れも増加し、酸素
約４０倍、アルゴン約１６倍、窒素は変化なし、空気約
２５倍、液約１９倍であった。次に、上記パルス幅τON
３５０μＳ、放電電流振幅Ｉp ２０Ａの場合の被加工体
の被加工面を観察したところ、液中と窒素の場合に被加
工面に再凝固層が層状に形成されていて、窒素の場合の
再凝固層内に多数の穴が形成されていて、溶融加工屑等
の気体を巻き込んだ再付着が多いことが伺えたが、酸素
の場合には再凝固層の形成が殆ど見られなかった。そし
て、何れにしても、本発明の気中放電加工方法によれ
ば、従来通常の液中放電加工で電極消耗の大きいパルス
幅τONの小さい仕上げ加工の領域で加工電極の消耗が殆
ど生じないと言う優れた特徴があることが認められる。In order to confirm the effectiveness of the air discharge machining using a pressurized gas that chemically reacts with the material to be processed, argon, nitrogen, air, etc. were used as the pressurized gas as the processing medium.
Further, the electric discharge machining was performed under the following conditions in oxygen and the electric discharge machining liquid (kerosene), and the results shown in FIGS. 4 and 5 were obtained. Experimental machining conditions Discharge current amplitude Ip (A) 20 No-load voltage (V) 280 Applied machining voltage polarity PL Positive polarity Discharge pulse width τ ON (μS) 20, 350, and 1000 Duty factor (%) 71 Swing radius (μm) 30 Pressurized gas supply pressure (MPa) 0.3 Depth of cut (μm) 5 (however, τON: 20 μS) 15 (however, τON: 350 and 1000 μS) FIG. 4 shows the type of pressurized gas used and processing conditions. In the comparison chart of the processing speeds due to the difference, there is no processing result when the argon gas is used when the pulse width is 20 μS, because the processing could not be performed under the setting processing conditions of the pulse width. According to the figure, oxygen (O2, air is about 21% oxygen and about 7%) as a gas that chemically reacts with the workpiece material (iron: Fe).
When it is supplied with (8% nitrogen), the processing speed is the highest, and in the region near the finishing processing with a pulse width of 20 μS, it is about 10 times higher than in liquid processing and several times higher than in air. On the other hand, it can be seen that the inert gas (which does not chemically react with the material to be processed) argon can hardly be processed. This is because when the pressurized gas of the processing medium is oxygen and air containing 21% oxygen, the workpiece material melted by the electric discharge explosively burns due to the oxidation reaction, and the reaction heat generated thereby causes the workpiece to be processed. It is considered that the processing speed was increased because the melting region of the body was further expanded. Further, it is considered that the smaller the generated machining waste is, the larger the surface area is with respect to the same machining waste volume, so that the chemical reaction with the supply gas such as oxidation is promoted. It can be useful. On the other hand, in the case of nitrogen, since it has a certain degree of reactivity with iron of the workpiece material, and the nitride has high hardness and wear resistance, it is expected to be used as surface treatment as well. However, it is considered that the chemical reaction between nitrogen and iron, which is the material to be processed, is as vigorous as that of oxygen and does not generate reaction heat, so that the fusion zone does not expand and the processing speed does not increase. Further, in the case of argon, the processing amount is only the processing waste blown away by the argon gas flow to the outside without being reattached to the surface of the object to be processed in the processing gap. It is recognized that there is very little even under the processing conditions of. The above-described tendency and state of the machining speed are in agreement with the result of collation by obtaining the machining amount per discharge from the machining data obtained as described above. The machining mechanism of the method is not only due to the fact that the melted portion of the machining gap is blown away by the discharge shock and the pressurized gas flowing at high speed, but the workpiece material in the discharged portion of the workpiece is more than a part of the supplied pressurized gas. It can be seen that the chemical reaction with is greatly affecting the processing result. Therefore, in the air electric discharge machining method of the present invention, in order to enhance the efficiency of machining, the gas that chemically reacts with the workpiece material is heated and melted by the average machining electric discharge power under the set machining conditions, Furthermore, it seems that it is preferable to adjust the supply amount according to the amount of the work material to be melted and scattered, and as a method for this, the ratio of the gas that chemically reacts with the work material in the supplied pressurized gas Is increased like an oxygen-rich gas, or the gap flow rate or flow velocity of the pressurized gas is increased within a range where the arc column does not slip from the gap due to movement or the like. When the pulse width of the above processing conditions is 350 μS, the discharge current amplitude Ip is 60 A.
However, the increase in processing amount when using argon and nitrogen is 2
~ 3 times, about 20% increase for air, about 60 for oxygen
%, But in the case of in-liquid processing, processing stability is poor and about 1
It decreased to / 8. FIG. 5 is a comparison diagram of the machining electrode wear rate during the above-described machining. According to this data, the electrode wear rate of the machining electrode in the case of air and oxygen is extremely small regardless of the pulse width τON. , And oxygen is less than in the case of air, whereas in nitrogen and argon, the working electrode consumption rate increases as the pulse width increases, and in the case of argon, the rate of increase is high, and the discharge current amplitude is 6
When it was set to 0 A, all the components except nitrogen increased, oxygen was about 40 times, argon was about 16 times, nitrogen was unchanged, air was about 25 times, and liquid was about 19 times. Next, the pulse width τON
When the surface to be machined of the object to be machined at 350 μS and discharge current amplitude Ip of 20 A was observed, a resolidification layer was formed in layers on the surface to be machined in the case of liquid and nitrogen. It was found that a large number of holes were formed in the layer, and that many reattachments involving gas such as melt-processed dust were involved, but in the case of oxygen, formation of a resolidified layer was hardly seen. In any case, according to the air electric discharge machining method of the present invention, there is almost no wear of the machining electrode in the area of the finishing machining with a large pulse width τON, which has a large electrode wear in the conventional ordinary electric discharge machining. It is recognized that there are excellent features to say.

【００１９】そして、本発明の気中放電加工方法開発の
初期の段階である前記文献１の報告に於て、陽陰極とも
鋼（Ｓ４５Ｃ）を用いると共に、加圧空気流を流通させ
た状態での放電により、正極性での（電極）低消耗加工
の可能性が示唆されていた。そして、本発明者は、前記
文献３で報告したように、通常の放電加工の電極と被加
工物の組合せである銅電極対鋼被加工体の組合せでの正
極性の液中及び気中（加圧空気）での、パルス幅が２０
μＳから２５００μＳまでの加工に於て、電極消耗率
が、液中加工では従来より知られているパルス幅小で大
消耗率、パルス幅大で小消耗率であるのに対し、気中加
工ではパルス幅が小から大までの範囲にわたって加工電
極の消耗が殆どなく、仕上げ加工条件での正極性による
電極無消耗ないし低消耗加工実現の可能性を確認した。
そして、その際同時に、本発明の目的とする気中放電加
工の場合は、電極と被加工体間の放電によって生じた溶
融物や加工屑等が、液中加工の場合に比べ冷却されるの
が遅いので、電極と被加工体の対向加工間隙面等に再付
着することなく加工間隙外に排出され易く、又強制的な
排出作用に対しても排出され易くするための電極と被加
工体との組合せ構成として、相対向して形成される加工
間隙の加工面の面積が小さいこと、従って加工面の面積
をある程度以上大きくするには、薄肉厚幅の加工面の該
幅方向の最も好ましい値は、加工条件によって或る程度
異なると共に液中の場合よりも大きい放電アーク柱の径
程度、又はその数倍以内であるから、強度上問題がない
範囲で前記加工面は前記幅方向と交叉する方向に前記幅
の数倍以上の所望の長さにわたって延在するように形成
することが好ましく、そして前記加工屑等を加工間隙外
に速やかに排出するためには、前記被加工体と化学反応
作用を有する空気等の加工媒体を前記加工間隙に於て流
通路が短くなる前記加工面の略幅方向に流通させること
が好ましい訳であるから、前記加工電極としては薄肉厚
幅の筒状体で、被加工体被加工面と微細間隙を隔てて相
対向させた前記筒状体電極から前記被加工面の円環等の
環状加工間隙へと前記加工媒体の加圧気体を噴出させる
構成となるものであり、そしてさらに発生加工屑等の再
付着をある程度物理的及び機械的にも防止するために、
電極と被加工体間の略対向方向の軸の廻りの相対的な回
転及び前記対向方向の軸に対して略直角方向の微小半径
又はストロークの相対的な並進運動又は揺動運動の両方
又は何れか一方を付与した状態での放電加工とすること
が好ましいものである。Then, in the report of the above-mentioned reference 1 which is the initial stage of the development of the air discharge machining method of the present invention, steel (S45C) is used for both the positive and negative electrodes and a pressurized air flow is made to flow. It was suggested that the possibility of low-consumption (electrode) low-consumption machining with positive polarity was caused by the discharge of. Then, the present inventor, as reported in the above-mentioned Document 3, has a positive electrode in a liquid and in an air (in a combination of a copper electrode and a steel workpiece, which is a combination of a normal electric discharge machining electrode and a workpiece ( Pressurized air), pulse width is 20
In the machining from μS to 2500μS, the electrode wear rate is a large wear rate with a small pulse width and a small wear rate with a large pulse width, which is conventionally known in the submerged machining, whereas It was confirmed that there was almost no wear of the machining electrode over a range of small to large pulse widths, and that there was no electrode wear or low wear machining due to the positive polarity under the finishing conditions.
Then, at the same time, in the case of air electric discharge machining which is the object of the present invention, the melt or machining waste generated by the electric discharge between the electrode and the workpiece is cooled as compared with the case of submerged machining. Since it is slow, the electrode and the work piece can be easily discharged outside the work gap without reattaching to the facing work gap surface between the electrode and the work piece, and also for the forced discharge action. In order to increase the area of the machined surface of the machined surface of the machined gap formed opposite to each other, that is, to increase the area of the machined surface to a certain extent or more, it is most preferable in the width direction of the machined surface having a thin thickness. Since the value differs to some extent depending on the processing conditions and is within the diameter of the discharge arc column which is larger than that in the liquid, or within several times of the diameter, the processed surface intersects with the width direction within a range where there is no problem in strength. Desired to be several times larger than the width in the direction It is preferable to form it so as to extend over the length, and in order to promptly discharge the processing waste etc. out of the processing gap, a processing medium such as air having a chemical reaction with the object to be processed is processed. Since it is preferable that the machining electrode is circulated in the width direction of the machined surface where the flow passage is shortened in the gap, the machining electrode is a cylindrical body having a thin wall thickness and a fine gap between the machined surface and the machined surface. And pressurizing gas of the processing medium is ejected from the cylindrical electrodes opposed to each other to an annular processing gap such as an annulus of the surface to be processed, and further generated processing waste and the like. In order to prevent the redeposition of
Relative rotation about an axis in a substantially opposite direction between the electrode and the workpiece and / or relative translational movement or oscillating movement of a minute radius or stroke in a direction substantially perpendicular to the opposite direction axis. It is preferable that the electric discharge machining is performed in a state where one of them is applied.

【００２０】以上につき、実験データにより説明する
と、以下の通りである。 実験加工条件 無負荷電圧（Ｖ） ２８０ 印加電圧極性 液中 逆極性 気中 正極性 放電電流振幅Ｉp（Ａ） ２０ 電圧パルス幅τON（μＳ） ２０、６０、２１０、３５０、１０００、 １５００、２０００、及び２５００ 銅パイプ電極内径（φｍｍ） ８ 銅パイプ電極肉厚幅（ｍｍ） ０．３、０．５、１．０、３．５、及び ５．０ 回転数（ｒｐｍ） ５２ 並進（揺動）運動径（ｍｍ）肉厚幅の１０％ 加工媒体 液体 ケロシン：無噴流 加圧気体 空気：０．５ＭＰａThe above will be described below with reference to experimental data. Experimental processing conditions No-load voltage (V) 280 Applied voltage polarity In-liquid reverse polarity In-air positive polarity Discharge current amplitude Ip (A) 20 Voltage pulse width τ ON (μS) 20, 60, 210, 350, 1000, 1500, 2000, And 2500 Copper pipe electrode inner diameter (φ mm) 8 Copper pipe electrode wall thickness width (mm) 0.3, 0.5, 1.0, 3.5, and 5.0 Rotation speed (rpm) 52 Translation (swing) Movement diameter (mm) 10% of wall thickness Processing medium Liquid kerosene: No jet flow Pressurized gas Air: 0.5 MPa

【００２１】図６は、肉厚幅が０．３〜５．０ｍｍの銅
パイプ電極を用いた液中と気中での各加工の１放電パル
ス当りの加工量（ｍｍ³）と放電パルス幅（μＳ）との
関係を示すもので、圧縮空気噴流（以下気中と言う）で
は加工量は放電パルス幅と比例関係にあるのに対し、液
中では放電パルス幅τON≒１０００μＳまでは、どの肉
厚幅の銅パイプ電極でもパルス幅τONに比例するが、１
０００μＳを越えると肉厚幅の大きいものは加工量が減
少してくる。これは、パイプ電極の肉厚幅が厚く大きく
なると、放電中の加工間隙が加工液の分解気泡で含めら
れる時間の割合が多くなり、加工間隙の状態が気中放電
の状態に近づくためと思われる。FIG. 6 shows the machining amount per discharge pulse (mm ³ ) and the discharge pulse width of each machining in liquid and in air using a copper pipe electrode having a wall thickness width of 0.3 to 5.0 mm. In the compressed air jet (hereinafter referred to as "in the air"), the machining amount is proportional to the discharge pulse width, whereas in the liquid, the discharge pulse width τON ≈ 1000 μS Even with a thick copper pipe electrode, it is proportional to the pulse width τON, but 1
When it exceeds 000 μS, the processing amount of the one having a large thickness width decreases. This is probably because as the wall thickness of the pipe electrode becomes thicker and thicker, the machining gap during electrical discharge increases the proportion of time it is included in the decomposed bubbles of the machining fluid, and the state of the machining gap approaches the state of air discharge. Be done.

【００２２】図７は、放電パルス幅τONが３５０μＳの
ときのパイプ電極の肉厚幅と加工量との関係を示すもの
で、気中及び液中ともパイプ電極の肉厚幅が薄くなるに
従って加工量が増加するが、液中に比べて気中の場合の
方が変化率が大きく指数関数的になっている。肉厚の幅
が０．３ｍｍに於て気中の方が液中よりも加工量が多く
なっているのは、気中では空気噴流により溶融部が酸
化、更には窒化すると共に、肉厚幅が放電のアーク柱直
径と略同じ位となって、溶融加工屑の加工面等への再付
着が生じにくくなっている上に空気噴流によってその溶
融部の大部分が飛ばされて除去されるのに対し、液中は
無噴流のためもあって溶融部の除去割合が、冷却速度が
速いことから、少なくなるのではないかと思われる。そ
して、このようなパイプ電極の肉厚幅と加工量との関係
は、他の放電パルス幅の小さい領域と、より大きい領域
に於ても同様な傾向を示していた。FIG. 7 shows the relationship between the wall thickness of the pipe electrode and the machining amount when the discharge pulse width τON is 350 μS. The machining is performed as the wall thickness of the pipe electrode becomes thinner in both air and liquid. Although the amount increases, the rate of change is larger and exponential in the case of air than that of liquid. At a wall thickness of 0.3 mm, the processing amount in air is larger than in liquid. The reason is that the air jet jet oxidizes and further nitrids the melted portion in the air, Becomes almost the same as the diameter of the arc column of the discharge, making it difficult for re-adhesion of molten processing waste to the processing surface etc., and most of the molten portion is blown away and removed by the air jet. On the other hand, it is considered that the removal rate of the melted portion may decrease due to the high cooling rate, partly because there is no jet in the liquid. Further, such a relationship between the wall thickness width of the pipe electrode and the processing amount showed the same tendency in other regions where the discharge pulse width is small and where it is larger.

【００２３】図８は、パイプ電極の肉厚幅が上記０．３
ｍｍのときの放電パルス幅τONと電極消耗率（％）との
関係を示すもので、気中では全ての放電パルス幅τONに
亘たって加工電極の消耗が無いか、極低消耗であるのに
対し、液中加工では一般に知られている電極消耗の傾向
と一致し、パルス幅τONが小で消耗率が著増している。
液中加工での電極低消耗の原理は電極加工面への炭素の
付着で説明されているが、本発明の気中放電加工では、
炭素の存在はなく、上記低又は無消耗現象は、後述する
ように、被加工体材の電極加工面への付着によるものと
考えられる。In FIG. 8, the wall thickness of the pipe electrode is 0.3.
It shows the relationship between the discharge pulse width τON and the electrode wear rate (%) when the value is mm. In the air, there is no wear of the machining electrode over the entire discharge pulse width τON, or there is very low wear. On the other hand, in the submerged processing, the generally known tendency of electrode consumption is in agreement, the pulse width τON is small, and the consumption rate is remarkably increased.
The principle of low electrode consumption in submerged machining is explained by the adhesion of carbon to the electrode machining surface, but in air discharge machining of the present invention,
There is no carbon, and the low or no consumption phenomenon is considered to be due to the adhesion of the workpiece material to the electrode processing surface, as described later.

【００２４】図９は、上記パイプ電極の肉厚幅３．５ｍ
ｍのときの放電パルス幅τONと短絡率（％）を調べたも
ので、液中に比べて気中の場合は高く、パルス幅τONが
小さい程、その差は顕著となる。これは、高速空気噴流
で加工屑を排出している気中放電加工では、加工間隙長
が小さい放電開始間隙長（ｇｓ≒５μｍ）に近い値にな
るのが多くなるのに対し、噴流のない液中加工では、発
生加工屑が加工液に拘束されて加工間隙の加工屑濃度が
高く、加工間隙長が大きくなっているためと考えられ
る。そこで、気中加工での電極への回転の付与と並進
（揺動）運動の付与の影響を上記短絡率との関係で調べ
たところ、図１０の通りとなった。即ち、回転及び並進
（揺動）運動の付与は何れも短絡率を減少させるのに有
効で、特にパルス幅の小さい領域での付与効果が高く、
又両者の同時付与がより有効なことが判る。以上のこと
から、本発明気中加工の加工電極の肉厚幅の大きさは、
厚くても約３ｍｍ以下、好ましくは１〜２ｍｍ以下で、
最適値は、パルス条件によって相違があるものの、気中
放電時のアーク放電柱の径（放電電流振幅２０Ａ、放電
パルス幅２０μｓで約２００μｍ（＝０．２ｍｍ）前
後）と同等乃至は１．２〜２．０倍程度であるが、機械
的、熱的強度、及び放電電力供給等に問題を生じない約
０．０５ｍｍ以上、好ましくは０．１ｍｍ以上で１ｍｍ
以下とするのがよい。又、加圧気体の噴流圧力は、少な
くとも０．０５ＭＰａ以上、好ましくは０．０８〜０．
１ＭＰａ以上で、１．０ＭＰａ以下、好ましくは０．５
ＭＰａ以下とするのがよい。FIG. 9 shows a wall thickness of the pipe electrode of 3.5 m.
The discharge pulse width τON and the short-circuit rate (%) at m were examined, and the difference was more remarkable in the air than in the liquid, and the smaller the pulse width τON, the more remarkable the difference. This is because in air discharge machining in which machining chips are discharged by a high-speed air jet, the machining gap length often becomes a value close to the discharge start gap length (gs≈5 μm), but there is no jet flow. It is considered that in the submerged machining, the generated machining chips are restricted by the machining liquid, the concentration of the machining chips in the machining gap is high, and the machining gap length is large. Therefore, when the influence of the application of the rotation and the translation (oscillation) motion to the electrode in the aerial working was examined in relation to the above short-circuit rate, it was as shown in FIG. That is, both the rotation and the translational (oscillation) motions are effective in reducing the short-circuit rate, and the effect is high particularly in the region where the pulse width is small,
Also, it is understood that the simultaneous application of both is more effective. From the above, the size of the thickness width of the working electrode of the present invention is
At most about 3 mm or less, preferably 1-2 mm or less,
The optimum value is equal to or smaller than the diameter of the arc discharge column during air discharge (around 200 μm (= 0.2 mm) with a discharge current amplitude of 20 A and a discharge pulse width of 20 μs), although it differs depending on the pulse conditions. It is about 2.0 times, but about 0.05 mm or more, preferably 0.1 mm or more and 1 mm, which does not cause problems in mechanical, thermal strength, discharge power supply, and the like.
It is better to do the following. The jet pressure of the pressurized gas is at least 0.05 MPa or more, preferably 0.08 to 0.
1 MPa or more and 1.0 MPa or less, preferably 0.5 MPa
It is preferable that the pressure is not more than MPa.

【００２５】次に、本発明の気中放電加工方法に於ける
電極無消耗のメカニズム、要因を明らかにするために、
実験と熱伝導解析を行ったので、これについて説明す
る。図１１のＡは実験方法の電極・被加工体部分側断面
説明図、図１１のＢは測定方法の測定サンプルの製作説
明図、及び図１１のＣは測定方法に於ける除去深さと付
着層厚さの側断面説明図である。 実験加工条件 電極（銅、ｍｍ） １０×１０×２０ 被加工体（Ｓ４５Ｃ、ｍｍ） 内径φ５、外径φ１０円筒 無負荷電圧（Ｖ） ２８０ 電圧パルス幅（τON、μＳ） ２０ デューティファクタ（％） ７１ 放電電流振幅（Ａ） ２０ 並進（振動）運動半径（ｍｍ） ０．５ 以上の条件で、加工時間０〜４００ｓｅｃを変えた加工
を行い、各異なる加工時間の電極（銅）の銅部分の除去
深さと、該電極加工面への鋼被加工体材の付着層厚さを
測定したところ、図１２の結果が得られた。この図１２
によれば、電極（銅）の銅の加工面は、気中放電加工開
始時から極めて短い時間のうちに、一旦約２μｍの深さ
（電銅部基準面からの除去深さ）加工された後、加工が
進行せず、他方被加工体材の鋼は、加工開始直後から電
極加工面に付着し、約１分程度以内で、付着層厚さ約
８．５μｍで一定となり、即ち、一部の剥離除去とその
除去量と略等量の再付着とが繰り返され、そして前記付
着層厚さは、約３μｍもあれば、結果として電極無消耗
での加工が継続されることが分かった。Next, in order to clarify the mechanism and the cause of no electrode wear in the method of air discharge machining of the present invention,
Experiments and heat conduction analyzes have been performed, which will be explained. 11A is an explanatory view of the side of the electrode / workpiece part of the experimental method, FIG. 11B is an explanatory view of the production of the measurement sample of the measuring method, and C of FIG. 11 is the removal depth and the adhesion layer in the measuring method. It is a side section explanatory view of thickness. Experimental processing conditions Electrode (copper, mm) 10 × 10 × 20 Workpiece (S45C, mm) Inner diameter φ5, outer diameter φ10 Cylinder No load voltage (V) 280 Voltage pulse width (τON, μS) 20 Duty factor (%) 71 Discharge current amplitude (A) 20 Translational (vibration) radius of motion (mm) 0.5 Under the above conditions, machining with machining time changed from 0 to 400 sec, the copper portion of the electrode (copper) at different machining times When the removal depth and the thickness of the adhered layer of the steel workpiece material on the electrode processing surface were measured, the results shown in FIG. 12 were obtained. This FIG.
According to the above, the copper-worked surface of the electrode (copper) was once machined to a depth of about 2 μm (removal depth from the copper-copper reference surface) within an extremely short time from the start of air discharge processing. After that, the processing does not proceed, while the steel of the workpiece material adheres to the electrode processing surface immediately after the processing is started, and within about 1 minute, the adhesion layer thickness becomes constant at about 8.5 μm, that is, It was found that the peeling and removal of the portion and the re-deposition of the same amount as the removed amount were repeated, and if the thickness of the adhesion layer was about 3 μm, as a result, the processing without electrode consumption was continued. .

【００２６】上記の電極モデルは、銅などの熱伝導率の
高い加工電極に、該電極より高融点の被加工体材（鋼）
が付着した状態であるから、融点の高い物質が表面に付
着している状態で、単発放電を生じさせたときの電極の
非定常熱伝導解析を行い、付着の影響を調べるために、
図１３に示した境界条件下で軸対象モデルを用いて解析
を行った。図１３に於て、半径方向６５０μｍ、深さ方
向３４５μｍの計算領域を４０×６０のメッシュに分割
し、メッシュの大きさは半径方向については中心から３
０メッシュまでは５μｍ、それ以降は５０μｍ、深さ方
向に関しては、加工面から４５メッシュまでは１μｍ、
それ以降は２０μｍとした。本解析では気化熱、融解熱
を考慮したほか、絶縁破壊直後からのアーク柱の直径に
ついてはパルス幅をパラメータとして単発放電を行い、
生じた放電痕の直径をアーク柱直径と等しいとしてその
変化を求めた。鋼の付着層に相当するメッシュの熱物性
値に鋼の値を用いることで鋼の付着の影響を解析に反映
させ、鋼と銅の境界に於ける熱物性値については両者の
熱物性値の調和平均を用いた。下記は解析の諸条件であ
る。 熱伝導率 Ｗ／（ｍ・Ｋ） 銅 ３９８ 鋼 ５３ 比 熱 Ｊ／（ｋｇ・Ｋ） 銅 ３８６ 鋼 ４６０ 密 度 ｋｇ／ｍ³ 銅８８８０ 鋼７８７０ 図１４は、解析結果で、縦軸に放電パルスの放電経過時
間に対する加工電極加工面の被加工体材鋼の付着層を含
めた表面からの溶融深さとの関係を示している。これか
ら分かるように、被加工体材が付着していない場合（Ｃ
ｕ−ａｌｌ）は、放電開始後５μｓｅｃで最大１４μｍ
の深さまで溶融した後、溶融深さが減少し１０μｓｅｃ
以後では溶融していない。これはアーク柱が膨張するに
従い銅電極表面に入力される熱流束が減少し、表面温度
が低下すると共に再凝固するからである。一方、電極を
すべて鋼とした場合（Ｆｅ−ａｌｌ）は銅のようにピー
クは見られず、１０μｓｅｃを過ぎても漸増する傾向が
ある。これは、鋼は銅に比べ融点が高く、熱伝導率が小
さいためである。次に、銅電極表面に被加工体材が付着
した場合に注目すると、付着層厚さ１μｍ（Ｆｅ−ａｌ
ｌ）では付着していない場合とあまり変わらないが、付
着層厚さが３μｍ以上では付着の効果が表れる。例え
ば、絶縁破壊直後から５μｓｅｃ付近に於て、３μｍの
付着層がある場合、鋼付着層と銅部との境界では銅の融
点が低いため銅部分は溶融するが、鋼付着層は２μｍし
か溶融せず、残りの１μｍの鋼の部分は固相であるため
溶融した銅部分は除去されない。したがって、表面の溶
融部のみが除去されると考えると、付着層無し（Ｃｕ−
ａｌｌ）の場合は１４μｍ除去されるが、３μｍの付着
層があると表面から鋼が２μｍだけ除去され、銅部分の
除去はないことになる。又、付着層厚さが厚くなるにつ
れ溶融深さも深くなるが、どの付着層厚さでも付着層厚
さ以上の深さにはなっていないことが分かる。よって、
たとえ鋼の付着層と銅部の境界で銅の融点が低いため溶
融することがあっても銅部は消耗しないことになり、被
加工体材の付着が加工電極消耗に与える影響が大きいこ
とが明かとなった。The electrode model described above is applied to a processed electrode having a high thermal conductivity such as copper, and a workpiece material (steel) having a higher melting point than the electrode.
In the state where a substance with a high melting point is attached to the surface, the unsteady heat conduction analysis of the electrode when a single discharge is generated is performed to investigate the influence of the attachment.
Analysis was performed using the axial symmetry model under the boundary conditions shown in FIG. In FIG. 13, a calculation area of 650 μm in the radial direction and 345 μm in the depth direction is divided into 40 × 60 meshes, and the size of the mesh is 3 from the center in the radial direction.
5 μm up to 0 mesh, 50 μm thereafter, 1 μm from the machined surface to 45 mesh in the depth direction,
After that, the thickness was set to 20 μm. In this analysis, heat of vaporization and heat of fusion were taken into account, and the diameter of the arc column immediately after the dielectric breakdown was single-discharged using the pulse width as a parameter.
The diameter of the generated discharge mark was made equal to the diameter of the arc column, and the change was obtained. The effect of the adhesion of steel is reflected in the analysis by using the value of steel as the thermophysical property value of the mesh corresponding to the adhesion layer of steel, and the thermophysical property value at the boundary between steel and copper is Harmonic mean was used. The following are the conditions for analysis. Thermal conductivity W / (m · K) Copper 398 Steel 53 Specific heat J / (kg · K) Copper 386 Steel 460 Density kg / m ³ Copper 8880 Steel 7870 Fig. 14 shows the analysis results with the discharge pulse on the vertical axis. 2 shows the relationship between the discharge elapsed time and the melting depth from the surface including the adhesion layer of the material steel to be processed on the processed electrode processing surface. As can be seen, when the workpiece material is not attached (C
u-all) is 14 μm at maximum 5 μsec after the start of discharge.
After melting to the depth of 10 μsec
After that, it has not melted. This is because the heat flux input to the surface of the copper electrode decreases as the arc column expands, the surface temperature decreases, and the solidification again occurs. On the other hand, when all the electrodes are made of steel (Fe-all), no peak is seen unlike copper, and there is a tendency for the peak to gradually increase even after 10 μsec. This is because steel has a higher melting point and lower thermal conductivity than copper. Next, paying attention to the case where the workpiece material adheres to the surface of the copper electrode, the thickness of the adhered layer is 1 μm (Fe-al
In l), the effect is not so different from the case of no adhesion, but the effect of adhesion appears when the thickness of the adhesion layer is 3 μm or more. For example, if there is an adhesion layer of 3 μm in the vicinity of 5 μsec immediately after the dielectric breakdown, the copper portion melts at the boundary between the steel adhesion layer and the copper portion because the melting point of copper is low, but the steel adhesion layer melts only 2 μm. No, the remaining 1 μm steel part is the solid phase and the molten copper part is not removed. Therefore, considering that only the melted portion on the surface is removed, there is no adhesion layer (Cu-
In the case of all), 14 μm is removed, but if there is an adhesion layer of 3 μm, the steel is removed by 2 μm from the surface, and the copper portion is not removed. Further, as the thickness of the adhesion layer becomes thicker, the melting depth also becomes deeper, but it is understood that no depth of the adhesion layer is more than the thickness of the adhesion layer. Therefore,
Even if it melts because the melting point of copper is low at the boundary between the steel adhesion layer and the copper part, the copper part will not be consumed, and the adhesion of the workpiece material will have a large effect on the machining electrode wear. It became clear.

【００２７】ところで、一つの放電パルス中で、鋼の付
着と電極材料（鋼あるいは銅）の除去が同時に進行する
と仮定する。実際の連続放電は、加工電極面上へのある
点に放電が生じ、それ以外の表面にひと通り放電が生じ
た後、再びその点に放電が生じる。このようなサイクル
を繰り返す過程で、注目する点での銅表面の後退と鋼層
の成長をシミュレーションすることができる。基本とな
るひとつの放電パルス内のシミュレーションは次のよう
に行った。まず、放電パルス幅２０μｓｅｃを８つのス
テップに分割する。そして、各々の時間ステップ内で
は、まず電極に被加工体材が付着し、その後図１４で示
す溶融深さ分だけ除去されると考える。付着する被加工
体材の厚さは、図１４のＦｅ−ａｌｌの結果を用いて被
加工体がそのときに溶融する深さのＸ％と考える。以上
を注目する点で生じる放電について繰り返せば、加工中
の加工電極の表面状態の時間変化が求められることにな
る。図１５に上記Ｘの値を２５、５０、７５の３通りに
ついて計算した結果を示す。図では、注目する点で放電
が終了してから、それ以外の点でひと通りの放電が生じ
て再びその点に放電が戻ってくるまでの時間を省略し、
電極の表面状態の時間変化を連続的に示した。これから
分かるように、どのＸ値でも付着層厚さはある値以上に
なっていない。一方、銅部の除去深さについて見ると、
Ｘ値が７５では全く銅の除去がない。２５、５０では除
去されるが、除去は最初の放電時のみで、その後は除去
されないことが分かる。このシミュレーション結果と図
１２の測定結果が定性的に一致したことから、気中加工
の加工電極無消耗の要因は、電極に付着する被加工体材
の鋼であることが裏付けられた。このように、加工電極
無消耗加工ができるところから、加工電極９としては、
図１〜３でも説明したように、薄肉厚幅の筒状体のもの
とすることが望ましいのであるが、図３のＥ及びＦに示
したように、筒状体の先端断面を見た場合、必要に応じ
その一部以上をある程度耐熱性を有するセラミックスや
剛性樹脂、又は複合材等から成る高抵抗体や絶縁体１Ａ
で構成したものでも、該電極１を回転又は並進（揺動）
運動させながら加工するようにすることにより、気中放
電加工を継続させることができるものである。By the way, it is assumed that the deposition of steel and the removal of the electrode material (steel or copper) proceed simultaneously in one discharge pulse. In actual continuous discharge, discharge is generated at a certain point on the surface of the machining electrode, and discharge is generated again at all the other surfaces, and then again generated at that point. In the process of repeating such a cycle, the recession of the copper surface and the growth of the steel layer at the point of interest can be simulated. The basic simulation within one discharge pulse was performed as follows. First, the discharge pulse width of 20 μsec is divided into eight steps. Then, within each time step, it is considered that the workpiece material is first attached to the electrode and then removed by the melting depth shown in FIG. The thickness of the adhered workpiece material is considered to be X% of the depth at which the workpiece melts at that time using the result of Fe-all in FIG. By repeating the above with respect to the electric discharge that occurs at the point of interest, the time change of the surface state of the processing electrode during processing can be obtained. FIG. 15 shows the result of calculation of the value of X described above for three ways of 25, 50, and 75. In the figure, the time from the end of the discharge at the point of interest to the discharge at all other points and returning to that point again is omitted,
The time variation of the surface condition of the electrode is shown continuously. As can be seen, the adhesion layer thickness does not exceed a certain value at any X value. On the other hand, looking at the removal depth of the copper part,
When the X value is 75, there is no removal of copper. Although it is removed at 25 and 50, it can be seen that the removal is performed only at the first discharge and not thereafter. The qualitative agreement between the simulation result and the measurement result of FIG. 12 confirms that the cause of no consumption of the machining electrode in air machining is the steel of the workpiece material that adheres to the electrode. As described above, since the machining electrode 9 can be processed without wear, the machining electrode 9 is
As described with reference to FIGS. 1 to 3, it is desirable to use a thin-walled and thick-width tubular body. However, as shown in E and F of FIG. If necessary, a part or more of it is a high resistance body or an insulator 1A made of ceramics or a rigid resin having a certain degree of heat resistance or a composite material.
Even if it is composed of, the electrode 1 is rotated or translated (swing).
By performing machining while moving, air discharge machining can be continued.

【００２８】而して、前述図９の短絡率と放電パルス幅
τONとの関係、及び図１０の短絡率に対する回転と揺動
の効果のところでも指摘したところであるが、本発明
は、加工媒体として従来慣用の加工液の代わりに被加工
体材と化学反応をする気体を含有する加圧気体を用い、
正極性加工で、放電パルス幅τONの小から大の全領域に
亘たって加工電極無消耗ないし低消耗で、特に放電パル
ス幅τONの小さい仕上げ加工条件領域に於て電極無消耗
で、加工速度も液中加工よりも速いのであるが、放電開
始間隙（ｇｓ）長が液中の場合に比べて小さいだけでな
く、加工中の平均加工間隙長（ｇｍ）も、液中の場合の
ように加工屑等の加工間隙内への滞留が小さいことか
ら、かなり小さいと考えられ、前記図９及び図１０の気
中放電加工は放電パルス幅τONの小さい領域で短絡率が
高いという実験データと略符合している。そしてこのた
め、既述の２〜３の実験例に於ては、放電加工用パルス
電源１６として、前述図１に示した無負荷電圧が約１０
０Ｖ前後の直流電圧源１７を電流制限抵抗１９と逆電圧
防止ダイオード２１とを介して接続した電子スイッチ素
子１８をオン・オフさせる最も通常型の間歇的な主電圧
パルス電源に、無負荷電圧が高電圧（２８０Ｖ）の、通
常電流容量の小さい直流高電圧源又は該高電圧源を通常
型の主パルス電源の電圧パルスと同期又は適宜の位相差
を有する高電圧の電圧パルス電源から成る補助電源を設
けたものを用い、電極と被加工体間の放電繰返し周波数
をできるだけ低減させないで平均加工間隙長が広まるよ
うに平均加工電圧を高くして加工することにより、短絡
率を低減させて有効放電頻度を高めて加工するようにし
たもので、図１６により上述の如き１つの高電圧の補助
電源と、更にこれに加えてより高電圧の補助電源を付設
した本発明の加工方法に用いて有効な放電加工用パルス
電源の一実施例を示す。図に於て、１６は前述最も普通
で常用の休止時間を置いて間歇的な矩形波の加工用電圧
パルスを生成供給するノーマル主電源回路で、通常無負
荷電圧約６０〜１２０Ｖの加工用主直流電圧源１７を備
えているのに対し、上記第１の補助電源３２は、電圧約
２８０Ｖで電流容量の小さい直流高電圧源３２Ａ、逆電
圧防止ダイオード３２Ｂ、電流制限抵抗３２Ｃ、及び電
子スイッチ素子３２Ｄの直列接続回路を開閉スイッチ３
３によって主電源回路１６に並列に接続可能に構成さ
れ、前記電子スイッチ素子３２Ｄをパルス条件設定制御
装置２０によって主電源回路１６のスイッチ素子１８に
同期又は適宜のパルス幅で適宜の位相差を有する高電圧
小電流の電圧パルスを加工間隙に供給し、加工間隙の平
均加工電圧を高め、加工間隙長を広く保った状態での気
中放電加工を可能とするのである。なお、３０は間隙並
列抵抗、３１は極性切換器で、本発明の気中放電加工時
は正極性に設定されるものである。以上の第１の補助電
源３２を設けた気中放電加工は、既にいくつかの実験例
で見てきたように、短絡率はかなり高いことから、更に
高電圧の第２の補助電源３４を付設して加工を行った。
即ち、無負荷電圧約５００Ｖの電流容量の小さい直流高
電圧源３４Ａと逆電圧防止ダイオード３４Ｂ及び電流制
限高抵抗３４Ｃの直列接続回路を開閉スイッチ３５を介
して加工間隙に並列に接続すると共に、オン・オフ電子
スイッチ素子３４Ｄを電圧源３４Ａと高抵抗３４Ｃの直
列回路に並列に接続し、パルス条件設定制御装置２０に
よって電子スイッチ素子３４Ｄを、主電源回路１６のス
イッチ素子１８と、例えば逆位相のオン・オフ制御をし
て、より高い電圧パルスを加工間隙に印加して、加工間
隙の平均加工電圧を高くし、加工状態検出装置２２によ
り加工間隙からの検出によるサーボ制御装置（図示せ
ず）への供給検出電圧を大きくし、加工間隙長の拡大状
態での加工を可能として、気中放電加工の加工性能を向
上させる。As described above, the relationship between the short circuit rate and the discharge pulse width τON in FIG. 9 and the effect of rotation and oscillation on the short circuit rate in FIG. 10 have been pointed out. As a pressurizing gas containing a gas that chemically reacts with the workpiece material instead of the conventionally used machining liquid,
With positive polarity machining, there is no wear or low wear of the machining electrode over the entire range from small to large discharge pulse width τON, especially in the finishing machining condition area where discharge pulse width τON is small, and the machining speed is also high. Although it is faster than submerged machining, not only is the discharge start gap (gs) length smaller than in liquid, but the average machining gap length (gm) during machining is the same as when machining in liquid. It is considered to be considerably small because the amount of dust and the like staying in the machining gap is small, and it is almost in agreement with the experimental data that the short circuit rate is high in the air discharge machining of FIGS. 9 and 10 where the discharge pulse width τON is small. are doing. For this reason, therefore, in the above-mentioned 2-3 experimental examples, the no-load voltage shown in FIG.
The most normal type intermittent main voltage pulse power supply for turning on / off the electronic switching device 18 in which the direct current voltage source 17 of about 0 V is connected via the current limiting resistor 19 and the reverse voltage prevention diode 21 Auxiliary power supply composed of a high voltage (280 V) direct current high voltage source having a small normal current capacity or a high voltage voltage pulse power source having the high voltage source synchronized with the voltage pulse of a normal type main pulse power source or having an appropriate phase difference By using the machine with the above, the average machining voltage is increased to widen the average machining gap length without reducing the discharge repetition frequency between the electrode and the workpiece as much as possible, thereby reducing the short circuit rate and effective discharge. The processing of the present invention is performed by increasing the frequency, and one auxiliary power supply of high voltage as described above according to FIG. 16 and additionally a supplementary power supply of higher voltage are additionally provided. Shows an embodiment of a valid discharge machining pulse power supply with the law. In the figure, reference numeral 16 is a normal main power supply circuit for generating and supplying a voltage pulse for machining a rectangular wave which is the most usual and has a regular rest time, and which is usually a no-load voltage of about 60 to 120 V. In contrast to the provision of the DC voltage source 17, the first auxiliary power source 32 has a DC high voltage source 32A having a voltage capacity of about 280V and a small current capacity, a reverse voltage prevention diode 32B, a current limiting resistor 32C, and an electronic switch element. Open / close switch 3 for 32D series connection circuit
3 is configured to be connectable in parallel to the main power supply circuit 16, and the electronic switch element 32D is synchronized with the switch element 18 of the main power supply circuit 16 by the pulse condition setting control device 20 or has an appropriate phase difference with an appropriate pulse width. A high-voltage small-current voltage pulse is supplied to the machining gap to increase the average machining voltage of the machining gap, thereby making it possible to perform electric discharge machining in the air while maintaining a wide machining gap length. In addition, 30 is a gap parallel resistance, 31 is a polarity switcher, and is set to a positive polarity at the time of the air electric discharge machining of this invention. In the above-mentioned air-electric discharge machining provided with the first auxiliary power supply 32, the short-circuit rate is considerably high as already seen in some experimental examples. Therefore, the second auxiliary power supply 34 of higher voltage is additionally provided. And processed.
That is, a series connection circuit of a direct current high voltage source 34A having a small current capacity of about 500 V with no load voltage, a reverse voltage prevention diode 34B, and a current limiting high resistance 34C is connected in parallel to the machining gap via the open / close switch 35 and is turned on. The off electronic switch element 34D is connected in parallel to the series circuit of the voltage source 34A and the high resistance 34C, and the electronic switch element 34D is connected to the switch element 18 of the main power supply circuit 16 by, for example, an opposite phase by the pulse condition setting control device 20. On / off control is performed to apply a higher voltage pulse to the machining gap to increase the average machining voltage of the machining gap, and a servo control device (not shown) based on detection from the machining gap by the machining state detection device 22. By increasing the detection voltage supplied to the machine, it becomes possible to machine in the state where the machining gap length is expanded, and the machining performance of air discharge machining is improved.

【００２９】図１７及び図１８は、本発明の気中放電加
工に於て、加工速度等加工性能を向上させるために、被
加工体材と発熱等の化学反応を過不足なく、又は好まし
い加工状態が生じる気体の供給量、即ち、主として流量
と流速、及び放電発生加工屑を電極・被加工体の加工間
隙面に再付着させることなく、かつ加工電極の肉厚幅の
大きさにもよるが、加工間隙に形成された放電柱を加工
間隙外へ滑らせることなく、前記加工屑を間隙外へ排出
させるに好ましい物理的、機械的力を発生させる気体の
供給圧力及び流速を知るために、圧縮空気を約２〜１５
Ｎｌ／ｍｉｎ、常用的には３〜１０Ｎｌ（但し、Ｎｌと
は基準状態、即ち、温度０℃、圧力を大気圧に換算した
流量）程度の流量で、供給圧力を異ならせて供給流通さ
せたときの切込み量（μｍ）に対する加工速度と１放電
パルス当りの加工量の特性曲線図である。 実験加工条件 無負荷電圧（Ｖ） ２８０、５００ 放電電流振幅（Ａ） ２０ 放電パルス幅（μＳ） ３５０ デューティファクタ（％） ７０ 並進（揺動）運動半径（μｍ） ３０ 回転数（ｒｐｍ） １８０ 圧縮空気供給圧力（ＭＰａ） ０．１、０．３、０．５ なお、電極・被加工体、及び切込み等の加工の態様は、
既述の通りである。FIG. 17 and FIG. 18 show that in the air-electric discharge machining of the present invention, in order to improve machining performance such as machining speed, the chemical reaction such as heat generation with the workpiece material is not excessive or insufficient, or preferable machining is performed. The amount of gas that causes a state, that is, mainly the flow rate and flow rate, and the amount of electric discharge machining dust that does not redeposit on the machining gap surface of the electrode / workpiece, and also depends on the thickness of the machining electrode. However, in order to know the supply pressure and the flow velocity of the gas that generate a physical and mechanical force preferable for discharging the machining waste to the outside of the machining gap without sliding the discharge column formed in the machining gap to the outside of the machining gap. , About 2 to 15 compressed air
Nl / min, ordinarily 3 to 10 Nl (however, Nl is a standard state, that is, a temperature of 0 ° C., a flow rate in which the pressure is converted to the atmospheric pressure), and the supply pressure is varied to supply and circulate. FIG. 9 is a characteristic curve diagram of the machining speed and the machining amount per discharge pulse with respect to the depth of cut (μm). Experimental processing conditions No-load voltage (V) 280, 500 Discharge current amplitude (A) 20 Discharge pulse width (μS) 350 Duty factor (%) 70 Translation (oscillation) radius of motion (μm) 30 Rotation speed (rpm) 180 Compression Air supply pressure (MPa) 0.1, 0.3, 0.5 In addition, the mode of processing such as electrodes / workpieces and notches is
As described above.

【００３０】気中加工では、極間に圧縮空気を供給する
ことによって極間の溶融部分の除去を促進しなければな
らない。したがって、極間に供給する空気圧力は強いほ
ど、加工速度が向上すると考えられる。しかし空気流速
が大き過ぎるとアーク柱が空気流の方向に流され、被加
工体表面上を滑るので加工速度が低下する。そこで、供
給圧力を変化させて供給圧力の影響を調べた。図１７に
加工速度の結果を示し、図１８に放電１回当りの加工量
の結果を示した。図中で０．１ＭＰａのプロットが途中
で終わっているのは、これ以上の切込み量では加工が非
常に不安定となり、その後の実験を行っていないためで
ある。図１８から分かるように、０．３ＭＰａの加工量
が最も多く、０．１ＭＰａがこれに続き、０．５ＭＰａ
が最小になっている。これは、供給空気圧力が大きいと
極間に流れる空気流量が過大になり、アーク柱が空気流
に沿って流され、被加工体が十分に溶融する前にアーク
柱が被加工体上を滑るからである。しかし、供給空気圧
力が小さすぎると空気流量が少なくなり、加工屑及び溶
融部分の酸化させる酸素量が不足して化学反応による加
工が促進せず、他方極間の溶融部分や酸化部分が十分に
除去されず極間に残留してしまうか、極間から除去され
たとしても加工屑が固化する前に極間の近傍の被加工体
上面に再付着する割合が多くなるので、放電１回当りの
加工量が減少すると考えられる。これが切込み量が大き
い場合、０．１ＰＭａが０．３ＰＭａよりも加工量が少
ない理由と考えられる。以上のことから、極間に流れる
空気流量に最適値が存在すると考えられ、上記の場合、
０．３ＭＰａがこれに相当するものと思われる。次に切
込み量との関係をみると、供給空気圧力に於ても切込み
量に最適値が存在することが想像される。これは、切込
み量が少ないと極間が広くなり、極間に流れる空気流量
が過大となって、前述の理由から加工量が少なくなった
ものと考えられる。又、一般に極間が広くなると加工量
が変化することが知られているが、その影響も原因の１
つとして考えられる。逆に切込み量が多くなった場合、
極間が狭くなるため極間の空気流量が減少し、加工屑の
排出が困難に陥ると同時に加工屑の再付着の割合が増加
するため加工量が減少するものと考えられる。図１９に
有効放電頻度の結果を示す。これから分かるように、
０．５ＭＰａは切込み量が増加するにつれ放電頻度は減
少しているが、０．１ＭＰａ、０．３ＭＰａでは放電頻
度を最大にする切込み量があることが分かる。切込み量
が大きすぎると極間が狭くなり、極間に流れる空気流量
が減少するため、後述するように短絡率が上昇するが、
これが切込み量２０μｍ以上で放電頻度が減少する原因
と考えられる。逆に、切込み量が少ないと極間が広いた
め放電頻度は低下する。図２０に前記短絡率の結果を示
すが、どの供給空気圧力に於ても切込み量が増加するに
つれ短絡率が増加していることが分かる。これは、切込
み量の増加にともない極間が狭くなるためであると考え
られる。In the aerial processing, it is necessary to promote the removal of the molten portion between the electrodes by supplying compressed air between the electrodes. Therefore, it is considered that the stronger the air pressure supplied between the poles, the higher the processing speed. However, when the air flow velocity is too high, the arc column is caused to flow in the direction of the air flow and slides on the surface of the workpiece, so that the machining speed decreases. Therefore, the influence of the supply pressure was investigated by changing the supply pressure. FIG. 17 shows the result of the processing speed, and FIG. 18 shows the result of the processing amount per discharge. The plot of 0.1 MPa in the figure ends halfway because the machining becomes very unstable with a cutting depth larger than this and no subsequent experiments have been conducted. As can be seen from FIG. 18, the processing amount of 0.3 MPa is the highest, followed by 0.1 MPa, and 0.5 MPa.
Has been minimized. This is because when the supply air pressure is large, the flow rate of air flowing between the poles becomes excessive, the arc column is flown along the air flow, and the arc column slides on the work piece before the work piece melts sufficiently. Because. However, if the supply air pressure is too low, the air flow rate will decrease, and the amount of oxygen to be oxidized in the processing waste and the molten portion will be insufficient to accelerate the processing by the chemical reaction. If it is not removed and remains in the gap between the gaps, or even if it is removed from the gap between the gaps, the rate of redeposition on the upper surface of the work piece in the vicinity of the gap before the solidification of the machining increases. It is considered that the processing amount of is reduced. This is considered to be the reason why the processing amount of 0.1 PMa is smaller than that of 0.3 PMa when the depth of cut is large. From the above, it is considered that there is an optimum value for the air flow rate flowing between the poles, and in the above case,
0.3 MPa seems to correspond to this. Next, looking at the relationship with the depth of cut, it can be imagined that there is an optimum value for the depth of cut even with the supply air pressure. It is considered that this is because when the depth of cut is small, the gap between the electrodes becomes wide, the flow rate of the air flowing between the gaps becomes excessive, and the processing amount becomes small for the reason described above. In addition, it is generally known that the machining amount changes when the gap is widened.
Can be considered as one. Conversely, if the depth of cut increases,
It is conceivable that the air flow rate between the poles decreases due to the narrow gap between the poles, making it difficult to discharge the machining waste, and at the same time increasing the rate of reattachment of the machining waste, reducing the machining amount. FIG. 19 shows the result of the effective discharge frequency. As you can see,
At 0.5 MPa, the discharge frequency decreases as the depth of cut increases, but at 0.1 MPa and 0.3 MPa, there is a depth of cut that maximizes the discharge frequency. If the depth of cut is too large, the gap between the poles will become narrower and the flow rate of the air flowing between the poles will decrease.
It is considered that this is the reason why the discharge frequency decreases when the depth of cut is 20 μm or more. On the contrary, when the depth of cut is small, the gap between the electrodes is wide, and thus the discharge frequency decreases. FIG. 20 shows the results of the short-circuit rate, and it can be seen that the short-circuit rate increases as the depth of cut increases at any supply air pressure. It is considered that this is because the gap between the electrodes becomes narrower as the depth of cut increases.

【００３１】以上は、図１６に於て、第１の補助電源３
２を併用した無負荷電圧が、２８０Ｖの場合で、更に第
２の補助電源３４をも同時に併用するようにして無負荷
電圧を５００Ｖとした場合の結果を図２１〜２３に示
す。図２１は、加工速度で、切込み量に抗して極間が広
まった様子がうかがえる。図２２に放電１回当りの加工
量の結果を示すが、高電圧を重畳した場合、０．３ＭＰ
ａと０．５ＭＰａの加工量が重畳前に比べて半分以下に
減少しているのに対して、０．１ＭＰａでは減少の度合
が少ない。これは、高電圧を重畳印加することにより極
間が広くなったためと考えられ、前段落でも述べたが、
空気流量が過大となり、アーク柱が被加工体上を滑るた
めだと考えられる。図２３に有効放電頻度の結果を示す
が、これによれば、供給空気圧力の大小に関わらず、高
電圧重畳の効果が表れていることが分かる。又、シンク
ロスコープによる放電電圧及び放電電流の波形観察によ
れば、電圧パルス印加後放電開始までの遅れ時間が、高
電圧重畳無しの場合よりも長くなっており、高電圧を重
畳すると、平均加工電圧の上昇により加工間隙が広がっ
て短絡の減少に効果があることが確かめられた。The above is the first auxiliary power supply 3 in FIG.
FIGS. 21 to 23 show the results when the no-load voltage using 280 is 280 V, and the second auxiliary power source 34 is also used at the same time to set the no-load voltage to 500 V. In FIG. 21, it can be seen that the machining gap has spread the gap between them against the depth of cut. Fig.22 shows the result of machining amount per discharge. When high voltage is superposed, 0.3MP
While the processing amounts of a and 0.5 MPa are reduced to less than half of those before the superimposition, the degree of reduction is small at 0.1 MPa. It is thought that this is because the gap between the electrodes was widened by applying the high voltage in a superimposed manner, and as described in the previous paragraph,
It is considered that the air flow rate becomes excessive and the arc column slides on the work piece. FIG. 23 shows the result of the effective discharge frequency, which shows that the effect of high voltage superimposition appears regardless of the magnitude of the supply air pressure. Moreover, according to the waveform observation of the discharge voltage and the discharge current by the synchroscope, the delay time from the application of the voltage pulse to the start of the discharge is longer than that without high voltage superposition. It was confirmed that the machining gap was expanded by increasing the voltage and it was effective in reducing short circuits.

【００３２】前述の如く、本発明の気中放電加工は穿孔
及び穴堀り加工にも適用可能であるがかかる気中放電加
工の実用化には、３次元の形状創成加工が行えることが
重要である。気中加工の場合、被加工体と加工電極の間
にほぼ均一に空気を流すことが肝要で、例えば、円筒電
極を用いて加工を行う場合、図２４のＡのように通常行
われている形状創成加工法では放電が生じている電極側
面に空気流が存在せず、加工屑の排出が不可能なため加
工が行えないことが考えられる。又、同図Ｂのように既
に荒取りが終了し、仕上げ加工を気中加工で行う場合、
加工電極と被加工体との極間が均一にできず、供給した
空気が放電の生じない極間の広い部分から逃げるため、
肝心の加工間隙に空気流がないので加工が行えないこと
が予想される。そこで、同図Ｃに示したように、常に電
極の端面で、かつ均一な極間で加工する加工電極経路を
考案し３次元形状創成加工を試みたところ、供給空気圧
力を０．３ＭＰａ、各ストロークの切込み量を１０μ
ｍ、高電圧重畳無しで他の加工条件を段落００２９に記
載した通りとして、底辺が約１５×２０ｍｍの凹状の角
錐台のように加工した結果、得られた断面曲線を図２５
に示した。加工に要した時間は８４分２０秒、得られた
加工面粗さはＲｍａｘで１０μｍである。図２５の断面
曲線から算出した加工電極の消耗率は０．６２％と非常
に少ない結果が得られた。又、図２５を見ると、得られ
た角度は略４５°と、作成したプログラムと殆ど同じ角
度が得られており、消耗率の低さを裏付けている。以上
のことから、気中加工は、３次元形状創成加工であって
も、電極経路を工夫することで加工が可能で、しかも無
消耗加工が行えることが明かとなった。As described above, the air electric discharge machining of the present invention can be applied to drilling and hole drilling, but it is important to be able to perform three-dimensional shape forming machining in order to put such air electric discharge machining into practical use. Is. In the case of air processing, it is essential to flow air almost uniformly between the workpiece and the processing electrode. For example, when processing is performed using a cylindrical electrode, it is usually performed as shown in A of FIG. In the shape generation processing method, it is considered that there is no air flow on the side surface of the electrode where the electric discharge is generated and it is impossible to discharge the processing waste, so that the processing cannot be performed. Further, as shown in FIG. 9B, when rough cutting has already been completed and the finishing process is performed in the air,
The gap between the machining electrode and the work piece cannot be made uniform, and the supplied air escapes from the wide area between the gaps where discharge does not occur.
It is expected that machining cannot be performed because there is no air flow in the essential machining gap. Then, as shown in FIG. 6C, when a three-dimensional shape generating process was attempted by devising a machining electrode path that always machined at the end face of the electrode and with uniform electrodes, the supply air pressure was 0.3 MPa, The stroke depth is 10μ
25, the cross-section curve obtained as a result of processing as a concave truncated pyramid having a bottom of about 15 × 20 mm with other processing conditions as described in paragraph 0029 without superimposing a high voltage is shown in FIG.
It was shown to. The time required for processing was 84 minutes and 20 seconds, and the obtained processed surface roughness was Rmax of 10 μm. The wear rate of the processed electrode calculated from the cross-sectional curve in FIG. 25 was 0.62%, which was a very small result. Further, as shown in FIG. 25, the obtained angle is about 45 °, which is almost the same as that of the created program, which confirms the low consumption rate. From the above, it has been clarified that even in the three-dimensional shape creating process, the in-air process can be performed by devising the electrode path and can be the non-consumable process.

【００３３】本発明は気中放電加工方法に於て、今迄に
解明した電極無消耗ノメカニズムによれば、その加工電
極と被加工体の材質組合せとしては、前記電極としては
銅等の熱伝導率の高いものであること、そして被加工体
としては、通常溶融状態の高温状態に於て酸素等の気体
と容易に又は高速での化学反応性を有することが前提で
あるか、電極材より高融点の鋼等の鉄材との組合せがよ
り好ましいものと考えられ、かかる観点によれば鉄系被
加工体に対する加工電極材として、例えばアルミニウム
（Ａｌ）、又はアルミニウム合金の適用が好適なものと
推定されるのであるが、前記文献１の報告に依れば、電
極及び被加工体をともに鋼として空気流中放電加工で、
正極性時に於て、電極低消耗特性を有することが既に報
告されていたことを考慮すると、本発明気中放電加工の
有望なことが明かである。According to the present invention, in the aerial electric discharge machining method, according to the mechanism of electrode non-consumption that has been clarified up to now, the material combination of the machining electrode and the object to be machined is that the electrode is made of heat such as copper. It is premised that it has a high conductivity, and that the object to be processed usually has a chemical reactivity with a gas such as oxygen easily or at a high speed in a high temperature state of a molten state, or an electrode material. It is considered that a combination with an iron material such as steel having a higher melting point is more preferable, and from this viewpoint, it is preferable to use, for example, aluminum (Al) or an aluminum alloy as a processing electrode material for an iron-based workpiece. According to the report of the above-mentioned Document 1, the electrodes and the work piece are both made of steel by the electric discharge machining in the air flow.
Considering that it has already been reported that the electrode has low wear characteristics when it has a positive polarity, it is clear that the air-electric discharge machining of the present invention is promising.

【００３４】そして、本発明の加工方法に於て、加圧圧
縮気体中に含有される被加工体材と化学反応をする気体
の選定及び含有割合を設定維持させることは比較的容易
であり、又上記圧縮気体の減圧弁出口の圧力及び流量調
整装置出口の流量、又は結果として筒状加工電極の加工
媒体入口部に於ける供給加工媒体の圧力及び流量は比較
的容易に設定値に維持させ易いものの、穿孔加工では回
転又は揺動する電極のＺ軸サーボ制御送り、又所謂創成
加工では放電加工中は切込み量の設定後Ｚ軸を固定した
としてもＹ軸１軸方向の加工送り方向に対して、ＸＹ軸
平面内のサーボ送り制御が為されているから、加工間隙
からの圧縮気体の一種の円板状ノズル態様の出口の口径
又は出口断面積は極めて小さいものの、可成り大きな変
化率で絶えず変化しており、通過する圧縮気体の気流を
発生加工屑や被加工面溶融部との接触状態の変化幅も大
きく、加工間隙を流通する加圧気体の圧力、流量、及び
流速は可成りの幅で変化し、加工状態が変化するから、
前記サーボ送り制御は高速応答で精密に制御する必要が
ある。In the processing method of the present invention, it is relatively easy to select and maintain the content ratio of the gas contained in the pressurized compressed gas that chemically reacts with the material to be processed, Further, the pressure of the compressed gas at the outlet of the pressure reducing valve and the flow rate at the outlet of the flow rate adjusting device, or as a result, the pressure and the flow rate of the supplied processing medium at the processing medium inlet of the cylindrical processing electrode, can be maintained at the set values relatively easily. Although easy, Z-axis servo control feed of rotating or oscillating electrode is used in drilling, and in so-called creation machining, even if the Z-axis is fixed after setting the depth of cut during electrical discharge machining, the machining feed direction is in the Y-axis 1-axis direction. On the other hand, since the servo feed control in the XY axis plane is performed, the diameter or outlet cross-sectional area of the outlet of a kind of disk-shaped nozzle of compressed gas from the machining gap is extremely small, but the change rate is considerably large. Constantly changing in The flow of compressed gas that passes through is large, and the range of changes in the state of contact with the processing waste and the molten portion of the surface to be processed is large, and the pressure, flow rate, and flow velocity of the pressurized gas flowing through the processing gap are fairly wide. It changes and the processing state changes,
The servo feed control needs to be precisely controlled with high speed response.

【００３５】而して、前記加工電極としては、筒状体の
肉厚幅が前述の如く大きくても３ｍｍ厚程度のものの、
従って使用する加工気体の量も前述の如く約２〜１５Ｎ
ｌ／ｍｉｎ程度、そして常用的には約３〜１０Ｎｌ／ｍ
ｉｎ程度であるから加工間隙からの加圧気体の噴射速度
は約２０〜２５０ｍ／ｓ、常用的には約５０〜２００ｍ
／ｓ程度の範囲内にものと考えられる。As the machining electrode, although the cylindrical body has a wall thickness of about 3 mm at the maximum as described above,
Therefore, the amount of processing gas used is about 2 to 15 N as described above.
l / min, and usually about 3 to 10 Nl / m
Since it is about in, the injection speed of the pressurized gas from the working gap is about 20 to 250 m / s, normally about 50 to 200 m.
It is considered to be within the range of about / s.

【００３６】本発明の気中放電加工方法により穿孔又は
穴堀り加工を行う場合、加工孔が、例えば電極径程度又
はそれ以上と深くなると、電極に並進（揺動）運動を与
えていたとしても加工屑の排出が困難となって加工困難
となる可能性があるが、かかる場合には図示等して説明
したＺ軸の上下を逆にする対応等も考えられるものであ
り、又加圧気体の供給の仕方等としても、例えば、圧縮
空気を供給するコンプレッサと圧縮酸素を供給する酸素
ボンベとを組合わせて所望の割合の酸素を含有するか圧
縮気体を供給するようにすることができる。尚、前述２
〜３の実験例に於けるパルス幅のデューティファクタ
が、何れも約７０％と言うのは格別技術的な意味はな
く、デューティファクタの加工性能との関係は、従来の
経験則と大きく相違するものは少なく、ただ被加工体材
と化学反応をする気体（酸素）をより多い割合で含有し
ている加圧気体を用いる加工の場合にデューティファク
タの増大がパルス幅の小さい、仕上げ加工の加工速度向
上と消耗率の減少に影響率が大きいと認められた。When performing the drilling or drilling by the air electric discharge machining method of the present invention, it is considered that the electrode is given a translational (swing) motion when the drilled hole becomes deeper, for example, about the electrode diameter or more. However, there is a possibility that it will be difficult to discharge the processing waste and it will be difficult to process, but in such a case, it is conceivable to turn the Z axis upside down as explained in the drawings and the like. As a method of supplying gas, for example, a compressor for supplying compressed air and an oxygen cylinder for supplying compressed oxygen may be combined to contain a desired proportion of oxygen or supply compressed gas. . The above 2
It is meaningless to say that the duty factor of the pulse width in each of the experimental examples (1) to (3) is about 70%, and the relationship between the duty factor and the machining performance is significantly different from the conventional empirical rule. There are few things, but in the case of processing using a pressurized gas containing a gas (oxygen) that chemically reacts with the workpiece material at a higher ratio, the increase of the duty factor is small and the pulse width is small. It was recognized that the rate of impact was large for speeding up and decreasing wear rate.

【００３７】[0037]

【発明の効果】以上述べてきたように、本発明の気中放
電加工方法は、未だ研究開発途上ではあるが、既に明ら
かになったように、加工速度が遅くかつ電極消耗率の大
きい従来型液中放電加工の残る弱点とされてきた仕上げ
加工領域の加工に於て、加工の仕方、態様に制約がある
ものの、電極無消耗で、加工速度の大きい加工ができる
ことから、大きな威力を発揮すると共に、被加工体材と
化学反応する気体と該気体を含有する圧力気体の供給装
置及び加工屑の回収処理装置等を必要とするものの、従
来型の液中放電加工用の可燃性の加工液も、又加工液の
循環処理供給装置も必要としないことによる多くの利点
を有するもので、放電加工に新しいページを開く有用な
発明であると確信するものである。As described above, although the air-electric discharge machining method of the present invention is still in the research and development stage, it has already been clarified that the conventional machining method has a slow machining speed and a large electrode consumption rate. In the machining of the finishing machining area, which has been regarded as a weak point of the electric discharge machining in liquid, there are restrictions on the machining method and mode, but the electrode is not consumed and machining can be performed at a high machining speed. In addition, a flammable machining liquid for conventional submerged electric discharge machining, which requires a gas that chemically reacts with the workpiece material, a pressure gas supply device containing the gas, a device for collecting and processing the machining waste, etc. In addition, it has many advantages by not requiring a circulating treatment supply device of machining fluid, and is convinced that it is a useful invention for opening a new page for electric discharge machining.

【図面の簡単な説明】[Brief description of drawings]

【図１】本発明気中放電加工方法を実施する一実施例装
置の全体構成の説明図である。FIG. 1 is an explanatory diagram of an overall configuration of an apparatus for carrying out an air-electric discharge machining method according to the present invention.

【図２】図１の放電加工機部の拡大側面説明図である。FIG. 2 is an enlarged side view of an electric discharge machine unit shown in FIG.

【図３】ＡないしＦは異なる筒状電極の横断面図であ
る。3A to 3F are cross-sectional views of different cylindrical electrodes.

【図４】異なる気体を加工媒体とする気中放電加工の加
工用電圧パルス幅に対する加工速度の特性図である。FIG. 4 is a characteristic diagram of a machining speed with respect to a machining voltage pulse width in air electric discharge machining using different gases as machining media.

【図５】図４と同様に、加工電圧パルス幅に対する加工
電極消耗率の特性図である。FIG. 5 is a characteristic diagram of a machining electrode wear rate with respect to a machining voltage pulse width, similar to FIG.

【図６】異なる肉厚幅の筒状電極で、液中と気中で放電
加工したときの加工用電圧パルス幅に対する１放電当り
の各加工量の特性曲線図である。FIG. 6 is a characteristic curve diagram of each machining amount per discharge with respect to a machining voltage pulse width when electric discharge machining is performed in a liquid and in air with cylindrical electrodes having different wall thicknesses.

【図７】筒状電極の異なる肉厚幅に対する液中と気中で
の加工の１放電当りの加工量の特性曲線図である。FIG. 7 is a characteristic curve diagram of a machining amount per discharge for machining in a liquid and in air for different wall thicknesses of a cylindrical electrode.

【図８】特定の肉厚幅の筒状電極使用による液中と気中
での加工の加工電圧パルス幅に対する電極消耗率の特性
曲線図である。FIG. 8 is a characteristic curve diagram of an electrode wear rate with respect to a machining voltage pulse width of machining in liquid and in air by using a cylindrical electrode having a specific wall thickness.

【図９】図８と同様に短絡率に関する特性曲線図であ
る。FIG. 9 is a characteristic curve diagram regarding the short-circuit rate, similar to FIG.

【図１０】加工電圧パルス幅に対する短絡率の特性に対
する電極回転と並進（揺動）運動付与の影響に関する特
性曲線図である。FIG. 10 is a characteristic curve diagram relating to the influence of application of electrode rotation and translational (swing) motion on the characteristic of the short circuit rate with respect to the machining voltage pulse width.

【図１１】Ａ、Ｂ、及びＣは、加工電極の消耗メカニズ
ムを測定するための実験及び測定方法に関する説明図で
ある。11A, 11B, and 11C are explanatory diagrams regarding an experiment and a measuring method for measuring the consumption mechanism of the working electrode.

【図１２】放電パルスの放電持続時間幅に対する電極の
除去深さと被加工体材付着層厚さの特性曲線図である。FIG. 12 is a characteristic curve diagram of an electrode removal depth and a work material adhesion layer thickness with respect to a discharge duration of a discharge pulse.

【図１３】電極の熱伝導解析に於ける解析モデルの説明
図である。FIG. 13 is an explanatory diagram of an analysis model in heat conduction analysis of electrodes.

【図１４】同解析結果の放電持続時間幅に対する溶融深
さの特性曲線図である。FIG. 14 is a characteristic curve diagram of melting depth with respect to discharge duration width of the analysis result.

【図１５】同シミュレーション結果の放電持続時間幅に
対する電極の除去深さと被加工体材付着層厚さの特性曲
線図である。FIG. 15 is a characteristic curve diagram of the electrode removal depth and the workpiece material attachment layer thickness with respect to the discharge duration width of the simulation result.

【図１６】本発明気中放電加工の実施に使用する改良さ
れた加工用パルス電源回路の概略構成を説明する結線図
である。FIG. 16 is a wiring diagram illustrating a schematic configuration of an improved machining pulse power supply circuit used for carrying out the air discharge machining of the present invention.

【図１７】異なる供給空気圧力の設定時に於ける加工切
込み量に対する加工速度の各特性曲線図である。FIG. 17 is a characteristic curve diagram of machining speed with respect to machining depth when different supply air pressures are set.

【図１８】同１放電パルス当りの加工量の特性曲線図で
ある。FIG. 18 is a characteristic curve diagram of the machining amount per discharge pulse.

【図１９】同有効放電頻度の特性曲線図である。FIG. 19 is a characteristic curve diagram of the same effective discharge frequency.

【図２０】同短絡率の特性曲線図である。FIG. 20 is a characteristic curve diagram of the same short circuit rate.

【図２１】図１７とこれに加工用電圧パルス電源に高電
圧パルスを重畳した場合の各加工速度の特性曲線図であ
る。FIG. 21 is a characteristic curve diagram of each processing speed when FIG. 17 and a high voltage pulse are superimposed on the processing voltage pulse power supply.

【図２２】同様に図１８とこれに高電圧パルスを重畳し
た場合の１放電パルス当りの加工量の特性曲線図であ
る。FIG. 22 is a characteristic curve diagram of the machining amount per discharge pulse when FIG. 18 and a high voltage pulse are superimposed on FIG.

【図２３】同様に図１９とこれに高電圧パルスを重畳し
た場合の有効放電頻度の特性曲線図である。23 is a characteristic curve diagram of FIG. 19 and the effective discharge frequency when a high voltage pulse is superposed on FIG.

【図２４】Ａ、Ｂ、Ｃは加工方法の説明図で、Ａ及びＢ
は本発明気中放電加工の適用が不適な加工の態様、そし
てＣは適用可能な加工の態様の各説明図である。24A, 24B and 24C are explanatory views of a processing method, and A and B
FIG. 3 is an explanatory view of a machining mode to which the air-electric discharge machining of the present invention is unsuitable, and C is a machining mode that is applicable.

【図２５】本発明気中放電加工方法を適用して加工した
加工モデルの縦断面説明図である。FIG. 25 is a vertical cross-sectional explanatory view of a machining model machined by applying the air discharge machining method of the present invention.

【符号の説明】[Explanation of symbols]

１，加工電極 ２，電極チャック ３，回転装置 ４，加工ヘッド ５，送りネジ ６，１２，１３，サーボモータ ７，エンコーダ ８，回転速度検出装置 ９，被加工体 １０，加工テーブル １１，ｘｙクロステーブル １４，駆動装置 １５，ＣＮＣ制御装置 １５Ａ，コンピュータ １５Ｂ，入力装置 １５Ｃ，記憶装置 １５Ｄ，数値制御装置 １６，放電加工用パルス電源 １７，直流電圧源 １８，電子スイッチ素子 １９，電流制限抵抗 ２０，電圧パルス条件設定装置 ２１，逆電圧防止ダイオード ２２，放電状態検出装置 ２３，圧縮気体供給装置 ２４，エアドライヤ ２５，減圧調整弁 ２６，流量計兼流量調整装置 ２７，基台 ２８，加工屑処理ノズル 1, processing electrode 2, electrode chuck 3, rotating device 4, processing head 5, feed screw 6, 12, 13, servo motor 7, encoder 8, rotational speed detection device 9, workpiece 10, processing table 11, xy cross Table 14, drive device 15, CNC control device 15A, computer 15B, input device 15C, storage device 15D, numerical control device 16, electric discharge machining pulse power source 17, DC voltage source 18, electronic switch element 19, current limiting resistor 20, Voltage pulse condition setting device 21, reverse voltage prevention diode 22, discharge state detection device 23, compressed gas supply device 24, air dryer 25, decompression adjustment valve 26, flow meter and flow rate adjustment device 27, base 28, processing chip processing nozzle

Claims (10)

【特許請求の範囲】[Claims] 【請求項１】 加工電極と被加工体とを微細な加工間隙
を隔てて相対向させると共に対向方向に相対的に近接開
離の加工送り及び送り位置決め制御可能に設け、前記加
工間隙に加工媒体を流通介在させた状態で前記電極、被
加工体間に直流電圧源を電子スイッチ素子をオン・オフ
制御することにより生成する休止時間を置いた間歇的な
電圧パルスを繰り返し印加し、発生する放電により被加
工体を加工する放電加工方法に於て、 前記加工電極の被加工体との相対向加工面が、大凡０．
０５〜３ｍｍの薄肉幅でこの幅方向と交叉する方向に前
記幅以上の長さにわたって延在し、被加工体の加工領域
の被加工面、又は該被加工面の一部と相対向し得る加工
面から成り、該加工電極の前記加工面のほぼ全面にわた
って被加工体の被加工面との間にほぼ均一な前記の微細
な加工間隙を形成させた状態として、該加工間隙に被加
工体材と化学反応をする気体を含有する加圧気体を加工
媒体として大凡前記幅方向に強制的に流通するように噴
射させて介在させた状態にすると共に、前記電極・被加
工体間のほぼ対向方向の軸の廻りの相対的な回転及び前
記対向方向の軸に対してほぼ直角方向の微細ストローク
の相対的な並進運動の両方又は何れか一方を付与させた
状態とし、前記印加電圧パルスによる放電を行なわせつ
つ前記対向方向の加工送りによる穿孔加工、又は前記対
向の所定の切込み量位置での被加工体の加工領域に対す
る電極加工面の対向部位を順次に移動させて加工するこ
とを特徴とする気中放電加工方法。1. A machining electrode and a work piece are made to face each other with a minute machining gap therebetween, and the machining feed and the feed positioning can be controlled so that the machining gap is relatively close in the opposing direction, and the machining medium is provided in the machining gap. Discharge generated by repeatedly applying intermittent voltage pulses with a dwell time generated by controlling the electronic switch element to turn on and off the direct current voltage source between the electrode and the work piece in a state where the In the electrical discharge machining method for machining a workpiece by means of the method described above, the machining surface of the machining electrode facing the workpiece is approximately 0.
It has a thin wall width of 05 to 3 mm and extends over a length greater than the width in a direction intersecting with the width direction, and may face a surface to be processed in a processing region of a workpiece or a part of the surface to be processed. The machining target is formed in the machining gap with a substantially uniform fine machining gap formed between the machining electrode and the machining surface of the machining electrode over substantially the entire machining surface of the machining electrode. A pressurized gas containing a gas that chemically reacts with the material is sprayed as a processing medium so that it is forcedly circulated in the width direction so as to be interposed, and the electrode and the workpiece are almost opposed to each other. Discharge by the applied voltage pulse, in a state where relative rotation about an axis in the direction of rotation and / or relative translational movement of a fine stroke in a direction substantially perpendicular to the axis in the opposite direction are applied. Of the opposite direction Drilling by Engineering feed, or given aerial discharge machining method characterized by machining the opposite portions of the electrode working surface is sequentially moved to with respect to the processing region of the workpiece at the infeed amount position of the counter. 【請求項２】 前記被加工体材と化学反応をする気体が
酸素であることを特徴とする請求項１記載の気中放電加
工方法。2. The air-electric discharge machining method according to claim 1, wherein the gas that chemically reacts with the workpiece is oxygen. 【請求項３】 前記被加工体材と化学反応をする気体を
含有する加圧気体が、圧縮空気、好ましくは空気より酸
素リッチの圧縮気体、又は圧縮酸素であることを特徴と
する請求項１記載の気中放電加工方法。3. The pressurized gas containing a gas that chemically reacts with the material to be processed is compressed air, preferably compressed gas richer in oxygen than air, or compressed oxygen. The air-electric discharge machining method described. 【請求項４】 前記加圧気体が前記加工間隙に少なくと
も０．０５ＭＰａ以上、１．０ＭＰａ以下の圧力で供給
された状態とすることを特徴とする請求項１，２、又は
３の何れか１に記載の気中放電加工方法。4. The method according to claim 1, wherein the pressurized gas is supplied to the processing gap at a pressure of at least 0.05 MPa and not more than 1.0 MPa. The air electric discharge machining method described in. 【請求項５】 前記加圧気体を、前記加工間隙に２０ｍ
／ｓ乃至２５０ｍ／ｓ、好ましくは５０ｍ／ｓ乃至２０
０ｍ／ｓの流速で流通介在させた状態とすることを特徴
とする請求項１，２、又は３の何れか１に記載の気中放
電加工方法。5. The pressurized gas is introduced into the processing gap by 20 m.
/ S to 250 m / s, preferably 50 m / s to 20
The air-electric discharge machining method according to any one of claims 1, 2 or 3, wherein the flow is interposed at a flow rate of 0 m / s. 【請求項６】 前記被加工体材と化学反応をする気体
が、当該設定加工条件下に於ける平均放電電力によって
加熱溶融、更には溶融飛散させられる被加工体材の量に
応じて供給量が制御されるものであることを特徴とする
請求項１，２，３，４、又は５の何れか１に記載の気中
放電加工方法。6. A supply amount of a gas that chemically reacts with the workpiece material, which is heated and melted by the average discharge power under the set processing conditions, and further, is melted and scattered according to the amount of the workpiece material. Is controlled, the air electric discharge machining method according to claim 1, 2, 3, 4, or 5. 【請求項７】 前記被加工体が鉄を主成分とする鉄系合
金で、前記加工電極が銅又は銅を主成分とする銅系合金
であることを特徴とする請求項１，２，３，４，５、又
は６の何れか１に記載の気中放電加工方法。7. The object to be processed is an iron-based alloy containing iron as a main component, and the processed electrode is copper or a copper-based alloy containing copper as a main component. , 4, 5, or 6, any one of the electrical discharge machining method in the air. 【請求項８】 前記加工電極が、薄肉厚幅の長尺筒状体
又は円筒状体から成ることを特徴とする請求項１，２，
３，４，５，６、又は７の何れか１に記載の気中放電加
工方法。8. The processing electrode is formed of a thin tubular body or a cylindrical body having a thin width.
3. The air electric discharge machining method according to any one of 3, 4, 5, 6, or 7. 【請求項９】 前記加工電極と被加工体間に休止時間を
置いて印加される間歇的な加工電圧パルスが、加工電極
を負極とする正極性として印加放電させられるものであ
ることを特徴とする請求項１，２，３，４，５，６，
７、又は８の何れか１に記載の気中放電加工方法。9. The intermittent machining voltage pulse applied with a dwell time between the machining electrode and the object to be processed is applied and discharged as a positive polarity with the machining electrode as a negative electrode. Claims 1, 2, 3, 4, 5, 6,
7. The air electric discharge machining method according to any one of 7 and 8. 【請求項１０】 前記加工電極と被加工体間に休止時間
を置いて供給される放電電力が、無負荷電圧が１００Ｖ
前後の電圧が低くて放電電流の大きい主加工用パルス電
源と、無負荷電圧が２００Ｖ以上の高電圧で電流容量が
小さい少なくとも１つの補助パルス電源との並設により
供給されるものであることを特徴とする請求項１，２，
３，４，５，６，７，８、又は９の何れか１に記載の気
中放電加工方法。10. The discharge power supplied with a pause between the machining electrode and the workpiece has a no-load voltage of 100V.
It is to be supplied by a parallel arrangement of a main machining pulse power source having a low front and rear voltage and a large discharge current, and at least one auxiliary pulse power source having a high no-load voltage of 200 V or more and a small current capacity. Claims 1, 2, characterized in that
3. The air electric discharge machining method according to any one of 3, 4, 5, 6, 7, 8, or 9.