JP2003181725A - Electric discharge machining apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric discharge machining apparatus having both high machining accuracy and high machining speed and suitable for micromachining. <P>SOLUTION: The electric discharge machining apparatus machines a workpiece 6 by applying voltage to a gap defined between an electrode 6 and a workpiece 5 from a machining power source 1 to generate electric discharge and by relatively moving the electrode 6 and the workpiece 5. The apparatus comprises an interelectrode voltage dividing means 8 arranged in parallel to the gap of the electrodes of the electrode 6 and workpiece 5 for dividing the voltage between the discharge electrodes and a discharging state detecting means 10 comprising a comparator means 11 for outputting a logic signal by comparing a voltage proportional to potential difference generated at the gap of the electrodes detected from the interelectrode voltage dividing means 8 and a reference voltage, a pulse width extending means 12 for retaining a logic value for a given period of time triggered by either rise or decay of the logic signal, an OR means 13 for taking OR from the input and the output of the pulse width extending means 12, and a smoothing means 14 for smoothing the logic signal output of the OR means 13 to convert it into analogue voltage is provided. <P>COPYRIGHT: (C)2003,JPO

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、放電加工によって
被加工物を加工する放電加工装置に関し、特にワイヤ放
電研削加工によって５０マイクロメートル以下の微細軸
を高い加工精度で短時間で加工する放電加工装置に関す
る。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric discharge machining apparatus for machining a work piece by electric discharge machining, and in particular, electric discharge machining for machining a fine axis of 50 micrometers or less by wire machining with high machining accuracy in a short time. Regarding the device.

【０００２】[0002]

【従来の技術】放電加工は、放電現象を媒体として高精
度・微細形状の加工が容易であることなど多くの特色を
持つとともに、非接触加工である。このために、電極と
被加工物との間隔を常に放電発生に適した間隔に保持す
ることが必要になる。形彫り放電加工では、加工の進行
に従って電極と被加工物とが除去される量だけ常に極間
隔を追い込まなければならないが、、極間の加工くずや
ガスの発生、放電面形状の変化などに対応して放電極間
隔を維持することが必要になる。2. Description of the Related Art Electric discharge machining has many characteristics such as high precision and easy machining of fine shapes using an electric discharge phenomenon as a medium, and is non-contact machining. For this reason, it is necessary to always maintain the distance between the electrode and the workpiece at a distance suitable for generating an electric discharge. In die-sinking EDM, it is necessary to constantly push the gap between electrodes by the amount by which the electrode and the work piece are removed as the machining progresses.However, machining scraps between the electrodes, gas generation, changes in the shape of the discharge surface, etc. Correspondingly, it is necessary to maintain the discharge electrode spacing.

【０００３】また、特開平１−１０３２３４号で示され
るようなワイヤ放電研削加工は、通常の研削の砥石に相
当する部分にワイヤガイド上をゆっくり走行するワイヤ
の外部エッジを用い、回転する被加工物を円筒研削のよ
うにして加工する方法であるが、切れ込みをとる場合
に、加工の進行に従って電極と被加工物が除去される量
だけ常に極間隔を追い込まなければならず、形彫り放電
加工と同様に放電極間隔を維持することが必要になる。
ワイヤ放電加工では、被加工物の板厚が変化する場合に
は放電面積も変化するために放電加工量も変化し、一定
の電気的条件、一定速度で送った場合には溝幅が大きく
変化し、加工精度が大幅に低下する。つまり、加工面積
の変化に伴い、放電極間隔が変化するため、板厚の変化
に対応して放電極間隔を維持することが必要になる。Further, in wire electric discharge grinding as disclosed in Japanese Patent Laid-Open No. 1-103234, an outer edge of a wire slowly traveling on a wire guide is used for a portion corresponding to a grindstone for ordinary grinding, and a rotating workpiece is machined. It is a method of machining an object like cylindrical grinding, but when making a notch, it is necessary to always push in the polar interval by the amount that the electrode and the workpiece are removed as the machining progresses Similarly to the above, it is necessary to maintain the discharge electrode interval.
In wire electric discharge machining, the discharge area also changes when the plate thickness of the work piece changes, so the amount of electric discharge also changes, and the groove width changes significantly when feeding at constant electrical conditions and constant speed. However, the processing accuracy is significantly reduced. That is, since the discharge electrode interval changes with the change in the processing area, it is necessary to maintain the discharge electrode interval corresponding to the change in the plate thickness.

【０００４】このような課題を解決するために、一般的
には放電間隔の極間平均電圧をある基準電圧と比較し
て、極間平均電圧が一定になるように送り速度を変化さ
せる方法がとられている。さらに、送り速度だけでな
く、最適な電気的条件を計算機を用いて出力する方式も
ある（精密工学会 新版精密工作便覧 コロナ社 P46
5,P494 <1992>）。極間平均電圧検出によって、電極と
被加工物との短絡も検知可能である。In order to solve such a problem, generally, there is a method of comparing the inter-electrode average voltage of the discharge interval with a certain reference voltage and changing the feed rate so that the inter-electrode average voltage becomes constant. It is taken. Furthermore, there is also a method that outputs not only the feed rate but also the optimum electrical conditions using a computer (Precision Engineering Society New Edition Precision Machinery Handbook, Corona P46).
5, P494 <1992>). A short circuit between the electrode and the workpiece can be detected by detecting the average voltage between the electrodes.

【０００５】特開昭５９−７５２３号では、極間平均電
圧を一定になるように送り速度を制御する方法に加え
て、さらに、平均加工電流を検出し、被加工物とワイヤ
電極との相対速度、所望の加工溝幅から板厚検出を行
い、電気的加工条件を切り替えるワイヤカット放電加工
機を提供している。In Japanese Patent Laid-Open No. 59-7523, in addition to the method of controlling the feed rate so that the average voltage between electrodes is constant, the average machining current is further detected to determine the relative between the workpiece and the wire electrode. We provide a wire-cut electric discharge machine that detects sheet thickness from speed and desired machining groove width and switches electrical processing conditions.

【０００６】特開平１０−２３５５２１号では、前記ワ
イヤ放電研削加工において、単位時間当たりの放電回数
を計数し、この計数値を所定値と比較して、送り速度や
電極と被加工物間距離の放電加工条件を制御する放電加
工装置を提供している。これは、放電極間隔が狭くなる
にしたがって、放電回数が増加する性質を利用したもの
である。例えば、被加工物にうねりがある場合、山部で
は除去すべき放電加工量が多くなるため、放電回数が増
すので、送り速度を遅くすれば所望の放電加工量を供給
することが可能となり、短絡を防止し、放電間隔も一定
にできる。また、逆に谷部では除去すべき放電加工量が
少なくなるため、放電回数が減り、送り速度を速くする
ことによって、加工速度を速くすることができる。In Japanese Patent Laid-Open No. 10-235521, the number of electric discharges per unit time is counted in the wire electric discharge grinding, and the counted value is compared with a predetermined value to determine the feed rate and the distance between the electrode and the workpiece. Provided is an electric discharge machining apparatus that controls electric discharge machining conditions. This utilizes the property that the number of discharges increases as the spacing between the discharge electrodes becomes narrower. For example, if the workpiece has undulations, the amount of electrical discharge machining to be removed increases at the ridges, so the number of electrical discharges increases, so it is possible to supply the desired amount of electrical discharge machining by slowing the feed rate. A short circuit can be prevented and the discharge interval can be made constant. On the contrary, since the electric discharge machining amount to be removed is small in the valley portion, the number of electric discharges is reduced, and the machining speed can be increased by increasing the feeding speed.

【０００７】[0007]

【発明が解決しようとする課題】しかしながら、このよ
うな従来の放電加工機において、極間平均電圧や平均加
工電流を検出することによって、放電加工条件を制御す
る方法は、一定周期、一定幅のパルス電圧を極間に供給
するようなスイッチング素子を使用した回路に非常に有
効であるが、極間への電圧供給が不定期で、かつ放電エ
ネルギの供給期間が無供給期間に比較して無視できるほ
ど急峻なパルスを供給するコンデンサと抵抗の充放電を
利用した回路においては、極間平均電圧や平均加工電流
は無放電時とほとんど違いはみられないため、制御が難
しいという課題があった。また、極間平均電圧や極間平
均電流は、放電エネルギと放電頻度が組み合わされて出
力された結果であるので、粗加工と仕上げ加工とで放電
エネルギを変える場合などはピーク値やパルス幅などの
パラメータを考慮しなければならないため、基準点を比
例式などの単純計算では決められないという課題があっ
た。However, in such a conventional electric discharge machine, a method of controlling the electric discharge machining conditions by detecting the average voltage between the electrodes and the average machining current is a constant cycle and a constant width. It is very effective for a circuit that uses a switching element that supplies a pulse voltage between the electrodes, but the voltage supply between the electrodes is irregular, and the discharge energy supply period is ignored compared to the non-supply period. In a circuit that uses the charging and discharging of a capacitor and a resistor that supply a pulse that is as steep as possible, there is almost no difference between the average voltage between contacts and the average machining current when there is no discharge, so there is the problem that control is difficult. . In addition, since the inter-electrode average voltage and inter-electrode average current are the results output by combining the discharge energy and the discharge frequency, when changing the discharge energy between rough machining and finishing machining, the peak value, pulse width, etc. However, there is a problem that the reference point cannot be determined by a simple calculation such as a proportional expression because the parameter of must be taken into consideration.

【０００８】この点、特開平１０−２３５５２１号で
は、放電回数値を制御に用いているため、抵抗とコンデ
ンサの充放電を利用した回路においても有効である。し
かしながら、少なくとも一定時間の計数時間が必要であ
り、応答性の面で不利となるし、また別途短絡検出手段
が必要になるなど部品点数も多くなりコスト面の課題も
あった。さらに、５０マイクロメートル以下の微細軸を
加工するといった微細加工が必要な場合には、放電間隔
が短くなるとともに、放電を抑制する働きのある絶縁液
が進入しにくくなるため、放電パルスの減衰特性が悪化
し、１回の放電で数回の放電パルスの計数が行われるこ
ともあり、実際の放電回数の倍以上の放電回数を誤計数
する危険性がある。In this respect, in Japanese Patent Laid-Open No. 10-235521, the value of the number of discharges is used for control, so that it is also effective in a circuit using charge and discharge of a resistor and a capacitor. However, at least a certain time is required for counting, which is disadvantageous in terms of responsiveness, and a short-circuit detecting means is additionally required, so that the number of parts is increased and there is a problem in cost. Further, when fine machining such as machining a fine shaft of 50 micrometers or less is required, the discharge interval becomes short, and the insulating liquid that has a function of suppressing discharge does not easily enter. May occur, and discharge pulses may be counted several times in one discharge, and there is a risk of miscounting the number of discharges that is more than twice the actual number of discharges.

【０００９】本発明は、上記課題を解決するものであ
り、高い加工精度と高速性を兼ね備え、特に微細加工に
適した放電加工装置を提供することを目的とする。The present invention is intended to solve the above problems, and an object of the present invention is to provide an electric discharge machining apparatus having both high machining accuracy and high speed, which is particularly suitable for fine machining.

【００１０】[0010]

【課題を解決するための手段および作用・効果】上記目
的を達成するために請求項第１項記載の発明は、電極と
被加工物によって形成される間隔に加工用電源から電圧
を印加して放電を発生させるとともに、前記電極と前記
被加工物を相対移動させて前記被加工物の加工を行う放
電加工装置において、前記電極と前記被加工物との極間
隔と並列に設けられて放電極間の電圧を分圧する放電極
間電圧分圧手段を設けるとともに、前記放電極間電圧分
圧手段から検出された極間隔に発生する電位差に比例し
た電圧と基準電圧を比較して論理信号を出力するコンパ
レータ手段と、前記論理信号の立ち上がり、または立ち
下がりのいずれか一方をトリガとして一定時間論理値を
保持するパルス幅伸長手段と、前記パルス幅伸長手段の
入力と出力とで論理和をとる論理和手段と、前記論理和
手段の論理信号出力を平滑してアナログ電圧に変換する
平滑手段とからなる放電状態検出手段を設けた。本発明
によれば、放電極間隔に応じて変化する放電頻度を、誤
計数することなく、しかも速い応答でアナログ電圧に変
換することができるとともに、短絡検知も兼ね備えるこ
とができる。また、抵抗とコンデンサの充放電を利用し
た加工用電源を使用する場合においても放電頻度の差を
認識しやすい。さらに、放電頻度のみを検出することに
なるので、制御する上での基準点を求めやすく、よっ
て、高精度な加工を実現する上での極間隔の検知が可能
になる。In order to achieve the above object, the invention according to claim 1 applies a voltage from a machining power source to a gap formed by an electrode and a workpiece. In an electric discharge machine for generating an electric discharge and for moving the electrode and the workpiece relative to each other to machine the workpiece, a discharge electrode provided in parallel with a polar interval between the electrode and the workpiece. A voltage dividing means for dividing the voltage between the discharging electrodes is provided, and a voltage proportional to the potential difference generated in the pole interval detected from the voltage dividing means between the discharging electrodes is compared with a reference voltage to output a logical signal. And a comparator means, a pulse width extending means for holding a logical value for a certain period of time by using one of the rising edge and the falling edge of the logic signal as a trigger, and the input and output of the pulse width extending means. Provided a logical OR means taking the sum, the smooth discharge state detection means comprising a smoothing means into an analog voltage by a logic signal output of the logical sum means. According to the present invention, the discharge frequency that changes according to the discharge electrode interval can be converted into an analog voltage with a fast response without miscounting, and short-circuit detection can also be provided. Further, it is easy to recognize the difference in discharge frequency even when using a processing power source that uses charging and discharging of a resistor and a capacitor. Furthermore, since only the discharge frequency is detected, it is easy to obtain a reference point for control, and thus it is possible to detect the pole interval for realizing highly accurate machining.

【００１１】請求項第２項記載の発明は、前記放電状態
検出手段から出力されるアナログ電圧データと記憶手段
に記録されている加工用電源の設定値データとから前記
電極と前記被加工物との推定放電極間隔を演算する放電
極間隔演算手段と、前記放電極間隔演算手段の演算結果
から前記記憶手段に記録された前記電極と前記被加工物
の相対移動条件を修正する軸移動制御手段と、前記軸移
動制御手段により制御され前記修正された相対移動条件
に基づき前記電極と前記被加工物とが相対移動するよう
駆動する軸移動駆動手段とを備えるようにした。本発明
によれば、前記放電状態検出手段の出力から放電極間隔
を推定し、放電極間隔を一定に保つような機械的制御が
可能になり、高精度の加工が短時間で可能となる。According to a second aspect of the present invention, the electrode and the workpiece are identified from the analog voltage data output from the discharge state detecting means and the set value data of the processing power source recorded in the storage means. Discharge electrode interval calculation means for calculating the estimated discharge electrode distance, and axial movement control means for correcting the relative movement condition of the electrode and the workpiece recorded in the storage means from the calculation result of the discharge electrode distance calculation means. And an axial movement drive means that is driven by the axial movement control means so as to relatively move the electrode and the workpiece based on the corrected relative movement condition. According to the present invention, the discharge electrode interval can be estimated from the output of the discharge state detecting means, and mechanical control can be performed to keep the discharge electrode interval constant, and high-precision machining can be performed in a short time.

【００１２】請求項第３項記載の発明は、前記放電極間
隔演算手段の演算結果から前記記憶手段に記録された加
工用電源の電気的条件を修正する加工用電源制御手段を
備えるようにした。本発明によれば、前記放電状態検出
手段の出力から放電極間隔を推定し、放電極間隔を一定
に保つような電気的制御が可能になり、高精度の加工が
可能となる。According to a third aspect of the present invention, there is provided a machining power supply control means for correcting the electrical condition of the machining power supply recorded in the storage means from the calculation result of the discharge electrode interval calculation means. . According to the present invention, it is possible to estimate the discharge electrode interval from the output of the discharge state detection means and perform electrical control so as to keep the discharge electrode interval constant, thereby enabling highly accurate machining.

【００１３】請求項第４項記載の発明は、前記加工用電
源が直流電源と、抵抗と、コンデンサとからなる放電加
工装置において、前記直流電源の両極と並列に前記放電
極間電圧分圧手段で検出する無放電時の分圧電圧よりも
低い電圧になるような分圧比をもつ直流電源電圧分圧手
段を設けるとともに、前記直流電源電圧分圧手段の出力
電圧が前記コンパレータ部の基準電圧となるよう構成し
た。本発明によれば、直流電源が供給する印加電圧が変
化しても自動的にコンパレータ部のしきい値を補正する
ことができるため、高精度加工を行う上での条件設定が
簡易になる。According to a fourth aspect of the present invention, in the electric discharge machining apparatus in which the machining power source includes a DC power source, a resistor, and a capacitor, the voltage dividing means between the discharge electrodes is arranged in parallel with both electrodes of the DC power source. In addition to providing a DC power supply voltage dividing means having a voltage division ratio to be a voltage lower than the divided voltage at the time of no discharge detected by, the output voltage of the DC power supply voltage dividing means and the reference voltage of the comparator section. Configured to be. According to the present invention, the threshold value of the comparator unit can be automatically corrected even when the applied voltage supplied from the DC power source changes, so that the condition setting for high-precision machining becomes simple.

【００１４】請求項第５項記載の発明は、前記電極がワ
イヤ電極であり、前記被加工物が回転手段によって回転
する微細軸である前記放電加工装置において、前記ワイ
ヤ電極と前記微細軸の軸方向とが直交して走行するため
のワイヤガイドを備えた。本発明によれば、５０マイク
ロメートル以下の微細軸を高精度に加工することが出来
る。According to a fifth aspect of the present invention, in the electric discharge machining device wherein the electrode is a wire electrode and the workpiece is a fine shaft rotated by a rotating means, the wire electrode and the shaft of the fine shaft are provided. It was equipped with a wire guide for traveling orthogonal to the direction. According to the present invention, it is possible to process a fine axis of 50 micrometers or less with high accuracy.

【００１５】請求項第６項記載の発明は、前記電極を所
望の３次元形状にあらかじめ加工した工具電極とすると
ともに、該工具電極の３次元形状を前記被加工物に転写
するようにした。本発明によれば、形彫り放電加工装置
においても高精度の加工が可能となる。According to a sixth aspect of the present invention, the electrode is a tool electrode pre-machined into a desired three-dimensional shape, and the three-dimensional shape of the tool electrode is transferred to the workpiece. According to the present invention, high-precision machining is possible even in a die-sinking electric discharge machine.

【００１６】請求項第７項記載の発明は、前記電極がワ
イヤ電極であり、前記被加工物が板状導電体である放電
加工装置において、前記ワイヤ電極と板状導電体の面方
向とを直交させるとともに、前記ワイヤ電極と前記板状
導電体の相対位置を変化させるための少なくとも２軸以
上の軸移動手段を備えるようにした。本発明によれば、
ワイヤカット放電加工装置においても高精度の加工が可
能となる。According to a seventh aspect of the present invention, in an electric discharge machine in which the electrode is a wire electrode and the work piece is a plate-shaped conductor, the wire electrode and the plane direction of the plate-shaped conductor are set. It is arranged to be orthogonal to each other and to be provided with at least two or more axis moving means for changing the relative position of the wire electrode and the plate conductor. According to the invention,
High-precision machining is possible even with a wire-cut electric discharge machine.

【００１７】[0017]

【発明の実施の形態】以下、本発明の形態により添付図
面を参照して説明する。BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings.

【００１８】図１は本発明の実施に係る放電加工装置の
第１の構成例を示す。加工用電源１は、直流電源２、抵
抗３、およびコンデンサ４から構成される。直流電源２
のプラス極は被加工物５に接続され、直流電源２のマイ
ナス極は電極６に接続される。被加工物５と電極６との
間隔は、水や放電油などで満たされる。また、被加工物
５は上下左右に動作する軸移動駆動部７に接続されてい
る。直流電源２が直流電圧を印加すると、コンデンサ４
に電荷が充電され、コンデンサ４の端子間電圧が徐々に
上昇する。コンデンサ４の端子間電圧が、被加工物５と
電極６との間の間隔の放電開始電圧を超えたとき、被加
工物６と電極６との間で放電が発生する。このプロセス
の被加工物５と電極６との間の電位差の変化を放電極間
電圧分圧手段８で検出する。放電極間電圧分圧手段８
は、例えば、８．２メガオームの抵抗と１メガオームの
抵抗を直列に接続して、１メガオームの抵抗の両端にか
かる電位差を検出するといった十分に高い抵抗値での分
圧によって実現する。FIG. 1 shows a first configuration example of an electric discharge machine according to the present invention. The processing power supply 1 includes a DC power supply 2, a resistor 3, and a capacitor 4. DC power supply 2
Of the DC power source 2 is connected to the electrode 6. The space between the workpiece 5 and the electrode 6 is filled with water, discharge oil or the like. Further, the workpiece 5 is connected to an axial movement drive unit 7 that moves vertically and horizontally. When the DC power supply 2 applies a DC voltage, the capacitor 4
Is charged, and the voltage across the terminals of the capacitor 4 gradually rises. When the voltage between the terminals of the capacitor 4 exceeds the discharge start voltage in the interval between the work piece 5 and the electrode 6, a discharge is generated between the work piece 6 and the electrode 6. The change in the potential difference between the workpiece 5 and the electrode 6 in this process is detected by the inter-discharge voltage dividing means 8. Voltage dividing means 8 between discharge electrodes
Is realized by voltage division with a sufficiently high resistance value, for example, by connecting a resistance of 8.2 megohm and a resistance of 1 megohm in series and detecting the potential difference across both ends of the resistance of 1 megohm.

【００１９】また、直流電源２の両極間の電位差を直流
電源電圧分圧手段９によって検出する。直流電源電圧分
圧手段９も、十分に高い抵抗値での分圧によって実現す
るが、分圧比を放電極間電圧分圧手段８の分圧比よりも
やや大きくとるようにして、無放電時に放電極間電圧分
圧手段８が検出する電圧よりも常に直流電源電圧分圧手
段９が検出する電圧が低くなるようにする。例えば、放
電極間電圧分圧手段８が、８．２メガオームの抵抗と１
メガオームの抵抗で構成されるとき、直流電源電圧分圧
手段９を１０メガオームの抵抗と１メガオームの抵抗で
構成する。このとき、直流電源２の印加電圧を１００ボ
ルトにしたときには、十分にコンデンサ４が充電してい
るときの放電極間電圧分圧手段８の１メガオーム抵抗の
両端の電圧は、１０．８６ボルトになり、直流電源電圧
分圧手段９の１メガオーム抵抗の両端の電圧は、９．０
６ボルトになる。直流電圧２の印加電圧を変化すると、
それに応じて放電極間電圧分圧手段８の出力と直流電源
電圧分圧手段９が両者の比が常に一定値を保ちながら変
化する。つまり、コンデンサ４が十分に充電している状
態では、常に放電極間隔電圧分圧手段８よりも直流電源
電圧分圧手段９の方が小さい値となる。なお、放電極間
電圧分圧手段８の分圧比と直流電源電圧分圧手段９の分
圧比を等しい値にして、直流電源電圧分圧手段９の出力
をオペアンプなどを使って、任意の電圧値で減算する方
法により、コンデンサ４が十分に充電している状態のと
き常に放電極間電圧分圧手段８よりも直流電源電圧分圧
手段９の方が小さい値となるようにしてもよい。Further, the potential difference between the two electrodes of the DC power supply 2 is detected by the DC power supply voltage dividing means 9. The DC power supply voltage dividing means 9 is also realized by voltage division with a sufficiently high resistance value, but the voltage dividing ratio is set to be slightly larger than the voltage dividing ratio of the inter-electrode voltage dividing means 8 so as to discharge when there is no discharge. The voltage detected by the DC power supply voltage dividing means 9 is always lower than the voltage detected by the inter-electrode voltage dividing means 8. For example, the voltage dividing means 8 between the discharge electrodes has a resistance of 8.2 megohm and a
When it is configured with a resistance of mega ohm, the DC power supply voltage dividing means 9 is configured with a resistance of 10 mega ohm and a resistance of 1 mega ohm. At this time, when the applied voltage of the DC power supply 2 is set to 100 V, the voltage across the 1 megohm resistor of the inter-discharge electrode voltage dividing means 8 when the capacitor 4 is sufficiently charged becomes 10.86 V. Therefore, the voltage across the 1 megohm resistor of the DC power supply voltage dividing means 9 is 9.0.
It will be 6 volts. When the applied voltage of DC voltage 2 is changed,
In response to this, the output of the voltage dividing means 8 between the discharge electrodes and the DC power supply voltage dividing means 9 change while the ratio between them is always kept constant. That is, when the capacitor 4 is sufficiently charged, the DC power supply voltage dividing means 9 always has a smaller value than the discharge electrode interval voltage dividing means 8. It should be noted that the voltage division ratio between the discharge electrode voltage dividing means 8 and the DC power supply voltage dividing means 9 are set to the same value, and the output of the DC power supply voltage dividing means 9 is set to an arbitrary voltage value using an operational amplifier or the like. Alternatively, the DC power supply voltage dividing means 9 may have a smaller value than the inter-discharge electrode voltage dividing means 8 when the capacitor 4 is sufficiently charged.

【００２０】直流電源電圧分圧手段９の出力電圧を、放
電状態検出手段９内にあるコンパレータ手段１１の基準
電圧と入力し、放電極間電圧分圧手段８の出力電圧をコ
ンパレータ手段１１に入力する。さらに、パルス幅伸長
手段１２、論理和手段１３、平滑手段１４を経由して、
放電極間隔演算装置１５に放電頻度に比例するアナログ
信号を出力する。放電極間隔演算装置１５で、放電極間
隔を推定し、その推定値に基づいて、軸移動制御手段１
６に対して、速度変更指令や送り動作の一時的逆方向動
作指令などを行い、軸移動駆動手段を放電極間隔が一定
になるように動作させる。The output voltage of the DC power supply voltage dividing means 9 is input to the reference voltage of the comparator means 11 in the discharge state detecting means 9, and the output voltage of the inter-electrode voltage dividing means 8 is input to the comparator means 11. To do. Furthermore, via the pulse width expansion means 12, the logical sum means 13, and the smoothing means 14,
An analog signal proportional to the discharge frequency is output to the discharge electrode interval calculation device 15. The discharge electrode interval calculation device 15 estimates the discharge electrode interval, and based on the estimated value, the axis movement control means 1
6, a speed change command, a temporary reverse motion command of the feed motion, and the like are issued to operate the axis movement drive means so that the discharge electrode interval becomes constant.

【００２１】図２は本発明の実施に係る放電状態検出手
段の各部の波形を示す。放電極間電圧分圧手段８からの
出力１９の波形は２５のとおりであり、被加工物５と電
極６との極間隔で放電が発生すると、極間電位差は急激
に下降し、再度充電が開始される。下降した際に、極間
隔に放電油の進入が遅い場合など条件によっては振動が
見られる場合もある。FIG. 2 shows the waveform of each part of the discharge state detecting means according to the present invention. The waveform of the output 19 from the discharge electrode voltage dividing means 8 is as shown in 25. When discharge is generated at the gap between the workpiece 5 and the electrode 6, the potential difference between the electrodes sharply decreases and the charge is recharged. Be started. When descending, vibration may be seen depending on the conditions, such as when discharge oil is slowly entering the pole interval.

【００２２】一方、直流電源電圧分圧手段９からの出力
２０の波形は２６のとおりであり、直流電源２の印加電
圧が一定ならば放電のあるなしに依らず一定であり、そ
の値は、コンデンサ２が十分に充電したときの放電極間
電圧分圧手段の出力よりも低い値となっており、その差
がコンパレータ手段１１の出力２１が反転するしきい値
となっている。つまり、直流電源電圧分圧手段９の出力
電圧を、放電状態検出手段９内にあるコンパレータ手段
１１の基準電圧と入力し、放電極間電圧分圧手段８の出
力電圧をコンパレータ手段１１に入力した際に、コンデ
ンサ２が十分に充電しているときには放電極間電圧分圧
手段８の出力は基準電圧よりも高い状態であり、このと
きコンパレータ手段１１の出力がＬＯＷになるようにす
る。そして、放電が開始し、放電極間電圧分圧手段８の
出力が基準電圧よりも低い状態になったときには、コン
パレータ手段１１の出力はＨＩＧＨになり、波形２７の
ようになる。On the other hand, the waveform of the output 20 from the DC power supply voltage dividing means 9 is as shown by 26, and if the applied voltage of the DC power supply 2 is constant, it is constant regardless of whether or not there is discharge, and its value is The value is lower than the output of the voltage dividing means between discharge electrodes when the capacitor 2 is sufficiently charged, and the difference is the threshold value at which the output 21 of the comparator means 11 is inverted. That is, the output voltage of the DC power supply voltage dividing means 9 is inputted as the reference voltage of the comparator means 11 in the discharge state detecting means 9, and the output voltage of the inter-electrode voltage dividing means 8 is inputted to the comparator means 11. At this time, when the capacitor 2 is sufficiently charged, the output of the inter-discharge electrode voltage dividing means 8 is higher than the reference voltage, and at this time, the output of the comparator means 11 is set to LOW. Then, when the discharge is started and the output of the voltage dividing means 8 between the discharge electrodes becomes lower than the reference voltage, the output of the comparator means 11 becomes HIGH, as shown by the waveform 27.

【００２３】なお、仕上げ加工などで、被加工物５と電
極６との放電極間隔が狭く、水や放電油が進入しにくい
場合には、電圧が振動してしまう場合もあるため、１回
の放電で数回のパルスが放電時コンパレータ手段出力波
形２７に発生する可能性がある。放電時コンパレータ手
段出力２１は、２つに分岐され、一方はパルス幅伸長手
段１２に、他方は論理和手段１３に入力される。なお、
後者のパルス幅伸長手段１２を経由しない経路には、タ
イミングを調整するための遅延回路を挿入するのが望ま
しい。パルス幅伸長手段１２は、例えば単安定マルチバ
イブレータが使用され、入力パルスをトリガとして、任
意に設定した時間幅のパルスを出力し、その時間幅内に
入力されたパルスの立ち上がりについては無視さる。こ
れにより、放電時コンパレータ手段出力波形２７に、１
回の放電で複数のパルスが発生していても、１つのパル
ス、しかも一定の時間幅のパルスを出力するような放電
時パルス幅伸長手段出力波形２８になる。When the discharge electrode gap between the work piece 5 and the electrode 6 is narrow due to finishing work or the like, and water or discharge oil is difficult to enter, the voltage may oscillate, so that once. There is a possibility that several pulses will be generated in the output waveform 27 of the comparator means during discharge by the discharge. The discharging comparator means output 21 is branched into two, one is inputted to the pulse width extending means 12 and the other is inputted to the logical sum means 13. In addition,
It is desirable to insert a delay circuit for adjusting timing in a path that does not pass through the latter pulse width expansion means 12. The pulse width expansion means 12 uses, for example, a monostable multivibrator, outputs a pulse having an arbitrarily set time width by using an input pulse as a trigger, and ignores the rising edge of the pulse input within the time width. As a result, the output waveform 27 of the comparator means during discharging is 1
Even if a plurality of pulses are generated by one discharge, the pulse width expansion means output waveform 28 during discharge is such that one pulse is output and a pulse having a constant time width is output.

【００２４】また、放電周期はランダムであり、しかも
放電極間電圧分圧手段８から出力される電圧パルス幅は
放電周期に対して非常に短いので、放電極間電圧分圧手
段８の出力を直接平滑しても放電頻度の変化による平滑
信号の変化幅は小さいが、パルス幅伸長手段１２によっ
て、１回の放電によるパルス幅を長くすることによっ
て、放電頻度による平滑信号の変化幅を大きくすること
が可能となる。つまり、放電によるパルス幅は一定であ
るが、放電周期がランダムなために、放電頻度によって
平滑信号が大きく変化するのである。放電時パルス幅伸
長手段出力２２は、論理和手段１３に入力され、コンパ
レータ手段出力２１で分岐された片方の信号と論理和が
とられる。放電時には、パルス幅伸長手段出力波形２７
の波形がそのまま論理和手段出力波形２９となり、平滑
手段１４に入力され、放電頻度に応じて変化するアナロ
グ信号波形３０となる。Since the discharge cycle is random and the voltage pulse width output from the inter-discharge electrode voltage dividing means 8 is very short with respect to the discharge cycle, the output of the inter-discharge electrode voltage dividing means 8 is changed. Even if it is directly smoothed, the change width of the smoothed signal due to the change of the discharge frequency is small, but the pulse width expansion means 12 lengthens the pulse width of one discharge to increase the change width of the smoothed signal depending on the discharge frequency. It becomes possible. That is, the pulse width due to the discharge is constant, but the smoothing signal largely changes depending on the discharge frequency because the discharge cycle is random. The discharge pulse width expansion means output 22 is input to the logical sum means 13 and is logically summed with one of the signals branched by the comparator means output 21. At the time of discharge, the pulse width expansion means output waveform 27
Waveform becomes the output waveform 29 of the logical sum means as it is, is inputted to the smoothing means 14, and becomes the analog signal waveform 30 which changes according to the discharge frequency.

【００２５】以上は、被加工物５と電極６との間で正常
に放電が発生している場合であるが、短絡事故発生時に
は平滑手段出力２４が最大電圧で一定となり、短絡が検
知できる。The above is the case where the discharge is normally generated between the workpiece 5 and the electrode 6, but when the short circuit accident occurs, the smoothing means output 24 becomes constant at the maximum voltage, and the short circuit can be detected.

【００２６】図３は本発明の実施に係る短絡を検知した
場合の放電検出回路の各部の波形を示す。短絡が発生す
ると、放電極間電圧分圧手段８の出力は０ボルト、また
は０ボルトに近い値となる。従って、短絡によりコンパ
レータ手段１１の出力１９は、波形３３のように短絡発
生時から短絡が解除されるまでＨＩＧＨの状態を継続す
ることになる。このとき、パルス幅伸長手段１２は、短
絡発生時に一定幅のパルスを出力した後、その後、短絡
が解消されるまでＬＯＷのままとなる。FIG. 3 shows the waveform of each part of the discharge detection circuit when a short circuit according to the present invention is detected. When a short circuit occurs, the output of the voltage dividing means 8 between discharge electrodes becomes 0 volt or a value close to 0 volt. Therefore, due to the short circuit, the output 19 of the comparator means 11 continues to be in the HIGH state from the time of occurrence of the short circuit to the cancellation of the short circuit as indicated by the waveform 33. At this time, the pulse width expansion means 12 outputs a pulse having a constant width when a short circuit occurs, and thereafter remains LOW until the short circuit is resolved.

【００２７】一方、コンパレータ手段１１の出力１９に
ついて、短絡後はＨＩＧＨ状態を継続するため、論理和
手段１３の出力２３は波形３５のように短絡後はＨＩＧ
Ｈ状態を継続する。従って、平滑手段１４の出力２４は
波形３６のように最大電圧で一定となり、これを監視す
ることにより短絡を検出することができる。また、図２
のとおり、放電頻度が多くなるほど放電時の平滑手段出
力波形３０は高い値のアナログデータとなり、放電頻度
が多くなり過ぎた結果として短絡が生じ、図３の波形３
６のとおり最大電圧になるということで制御上の論理も
整合性があり、制御しやすくなっている。On the other hand, with respect to the output 19 of the comparator means 11, since the HIGH state is continued after the short circuit, the output 23 of the logical sum means 13 is HIG after the short circuit as shown by the waveform 35.
The H state is continued. Therefore, the output 24 of the smoothing means 14 becomes constant at the maximum voltage as shown by the waveform 36, and a short circuit can be detected by monitoring this. Also, FIG.
As the discharge frequency increases, the smoothing means output waveform 30 at the time of discharge becomes high-value analog data, and a short circuit occurs as a result of excessive discharge frequency, and the waveform 3 in FIG.
Since the maximum voltage is obtained as shown in 6, the control logic is consistent and easy to control.

【００２８】図４は本発明の実施に係る放電加工装置の
第２の構成例を示す。放電極間演算手段１４で、推定さ
れる放電極間隔に基づいて、記憶手段１７に記録された
加工用電源１の設定値と比較して、加工用電源制御手段
１８は加工用電源に対して、印加電圧変更指令などを行
い、放電極間隔が一定になるように動作させる。FIG. 4 shows a second configuration example of the electric discharge machine according to the present invention. On the basis of the estimated discharge electrode interval, the inter-discharge electrode calculation means 14 compares the set value of the processing power supply 1 recorded in the storage means 17, and the processing power supply control means 18 controls the processing power supply with respect to the processing power supply. , The applied voltage change command, etc., are operated so that the discharge electrode interval becomes constant.

【００２９】以上の実施例では、主にワイヤ放電研削加
工を例として説明したが、これに限定されるものではな
く、形彫り放電加工やワイヤカット放電加工に適用して
もよい。In the above embodiments, the wire electric discharge grinding was mainly described as an example, but the present invention is not limited to this and may be applied to die-sinking electric discharge machining or wire cut electric discharge machining.

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

【図１】本発明の実施に係る放電加工装置の第１の構成
例を示す図である。FIG. 1 is a diagram showing a first configuration example of an electric discharge machine according to an embodiment of the present invention.

【図２】本発明の実施に係る放電状態検出手段の各部の
波形を示す図である。FIG. 2 is a diagram showing a waveform of each part of the discharge state detecting means according to the embodiment of the present invention.

【図３】本発明の実施に係る短絡を検知した場合の放電
検出回路の各部の波形を示す図である。FIG. 3 is a diagram showing a waveform of each part of the discharge detection circuit when a short circuit according to an embodiment of the present invention is detected.

【図４】本発明の実施に係る放電加工装置の第２の構成
例を示す図である。FIG. 4 is a diagram showing a second configuration example of an electric discharge machine according to the present invention.

【符号の説明】[Explanation of symbols]

１…加工用電源、２…直流電源、３…抵抗、４…コンデ
ンサ、５…被加工物、６…電極、７…軸移動駆動手段、
８…放電極間電圧分圧手段、９…直流電源電圧分圧手
段、１０…放電状態検出手段、１１…コンパレータ手
段、１２…パルス幅伸長手段、１３…論理和手段、１４
…平滑手段、１５…放電極間演算部、１６…軸移動制御
部、１７…記憶部、１８…加工用電源制御部、１９…放
電極間電圧分圧手段分圧電圧、２０…直流電源電圧分圧
手段分圧電圧、２１…コンパレータ部出力、２２…パル
ス幅伸長手段出力、２３…論理和手段出力、２４…平滑
手段出力、２５…放電時放電極間分圧手段分圧電圧波
形、２６…放電時直流電源電圧分圧手段分圧電圧波形 ２７…放電時コンパレータ部出力波形、２８…放電時パ
ルス幅伸長手段出力波形、２９…放電時論理和手段出力
波形、３０…放電時平滑手段出力波形 ３１…短絡時放電極間分圧手段分圧電圧波形、３２…短
絡時直流電源電圧分圧手段分圧電圧波形 ３３…短絡時コンパレータ部出力波形、３４…短絡時パ
ルス幅伸長手段出力波形、３５…短絡時論理和手段出力
波形、３６…短絡時平滑手段出力波形1 ... Machining power supply, 2 ... DC power supply, 3 ... Resistance, 4 ... Capacitor, 5 ... Workpiece, 6 ... Electrode, 7 ... Shaft movement drive means,
8 ... Discharge electrode voltage dividing means, 9 ... DC power supply voltage dividing means, 10 ... Discharge state detecting means, 11 ... Comparator means, 12 ... Pulse width extending means, 13 ... Logical sum means, 14
... smoothing means, 15 ... discharge electrode calculation unit, 16 ... axis movement control unit, 17 ... storage unit, 18 ... machining power supply control unit, 19 ... discharge electrode voltage dividing means voltage dividing voltage, 20 ... DC power supply voltage Voltage dividing means divided voltage, 21 ... Comparator section output, 22 ... Pulse width expansion means output, 23 ... Logical sum means output, 24 ... Smoothing means output, 25 ... Discharging inter-electrode voltage dividing means divided voltage waveform, 26 Discharge DC power supply voltage dividing means Divided voltage waveform 27 Discharge comparator output waveform 28 Discharge pulse width expansion means output waveform 29 Discharge logical sum output waveform 30 Discharge smoothing means output Waveform 31 ... Voltage waveform between voltage dividing means between discharge electrodes at short circuit, 32 ... Voltage waveform of DC power source voltage dividing means at short circuit, voltage waveform 33 ... Comparator output waveform at short circuit, 34 ... Pulse width expansion means output waveform at short circuit, 35 ... Output of OR means at short circuit Form, 36 ... short-circuit smoothing means output waveform

Claims (7)

【特許請求の範囲】[Claims] 【請求項１】 電極と被加工物によって形成される間隔
に加工用電源から電圧を印加して放電を発生させるとと
もに、前記電極と前記被加工物を相対移動させて前記被
加工物の加工を行う放電加工装置において、前記電極と
前記被加工物との極間隔と並列に設けられて放電極間の
電圧を分圧する放電極間電圧分圧手段を設けるととも
に、前記放電極間電圧分圧手段から検出された極間隔に
発生する電位差に比例した電圧と基準電圧を比較して論
理信号を出力するコンパレータ手段と、前記論理信号の
立ち上がり、または立ち下がりのいずれか一方をトリガ
として一定時間論理値を保持するパルス幅伸長手段と、
前記パルス幅伸長手段の入力と出力とで論理和をとる論
理和手段と、前記論理和手段の論理信号出力を平滑して
アナログ電圧に変換する平滑手段とからなる放電状態検
出手段を設けたことを特徴とする放電加工装置。1. A machining power source applies a voltage to a gap formed by an electrode and a workpiece to generate a discharge, and the electrode and the workpiece are moved relative to each other to process the workpiece. In the electric discharge machining device for performing, an inter-discharge electrode voltage dividing means is provided in parallel with a polar interval between the electrode and the workpiece to divide a voltage between the discharge electrodes, and the inter-discharge electrode voltage dividing means is provided. The comparator means for comparing the voltage proportional to the potential difference generated in the pole interval detected from the reference voltage with the reference voltage and outputting the logic signal, and the logical value for a certain period of time triggered by either one of the rising edge and the falling edge of the logical signal. Pulse width extending means for holding
Discharge state detecting means is provided which comprises a logical sum means for taking a logical sum of the input and output of the pulse width expanding means, and a smoothing means for smoothing the logical signal output of the logical sum means to convert it into an analog voltage. Electric discharge machine characterized by. 【請求項２】 前記放電状態検出手段から出力されるア
ナログ電圧データと記憶手段に記録されている加工用電
源の設定値データとから前記電極と前記被加工物との推
定放電極間隔を演算する放電極間隔演算手段と、前記放
電極間隔演算手段の演算結果から前記記憶手段に記録さ
れた前記電極と前記被加工物の相対移動条件を修正する
軸移動制御手段と、前記軸移動制御手段により制御され
前記修正された相対移動条件に基づき前記電極と前記被
加工物とが相対移動するよう駆動する軸移動駆動手段と
を備えたことを特徴とする請求項１記載の放電加工装
置。2. An estimated discharge electrode distance between the electrode and the workpiece is calculated from analog voltage data output from the discharge state detection means and setting value data of the processing power source recorded in the storage means. The discharge electrode interval calculation means, the axis movement control means for correcting the relative movement condition of the electrode and the workpiece recorded in the storage means from the calculation result of the discharge electrode distance calculation means, and the axis movement control means. The electric discharge machining apparatus according to claim 1, further comprising: an axial movement driving unit that drives the electrode and the workpiece to move relative to each other based on the controlled relative movement condition that has been corrected. 【請求項３】前記放電極間隔演算手段の演算結果から前
記記憶手段に記録された加工用電源の電気的条件を修正
する加工用電源制御手段を備えたことを特徴とする請求
項１及至２記載の放電加工装置。3. A machining power supply control means for correcting the electrical condition of the machining power supply recorded in the storage means from the calculation result of the discharge electrode interval calculation means. The electric discharge machine described. 【請求項４】 前記加工用電源が直流電源と、抵抗と、
コンデンサとからなる放電加工装置において、前記直流
電源の両極と並列に前記放電極間電圧分圧手段で検出す
る無放電時の分圧電圧よりも低い電圧になるような分圧
比をもつ直流電源電圧分圧手段を設けるとともに、前記
直流電源電圧分圧手段の出力電圧が前記コンパレータ部
の基準電圧となるよう構成したことを特徴とする請求項
１及至３記載記載の放電加工装置。4. The processing power source is a direct current power source, a resistor,
In an electric discharge machine comprising a capacitor, a DC power supply voltage having a voltage division ratio such that the voltage is lower than the voltage division voltage at the time of no discharge detected by the voltage dividing means between the discharge electrodes in parallel with both electrodes of the DC power supply. 4. The electric discharge machine according to claim 1, wherein the voltage dividing means is provided and the output voltage of the DC power supply voltage dividing means is configured to be a reference voltage of the comparator section. 【請求項５】 前記電極がワイヤ電極であり、前記被加
工物が回転手段によって回転する微細軸である前記放電
加工装置において、前記ワイヤ電極と前記微細軸の軸方
向とが直交して走行するためのワイヤガイドを備えたこ
とを特徴とする請求項１及至４の放電加工装置。5. In the electric discharge machining apparatus, wherein the electrode is a wire electrode and the workpiece is a fine shaft rotated by a rotating means, the wire electrode and the fine shaft run in a direction orthogonal to each other. An electric discharge machine according to any one of claims 1 to 4, further comprising a wire guide. 【請求項６】 前記電極を所望の３次元形状にあらかじ
め加工した工具電極とするとともに、該工具電極の３次
元形状を前記被加工物に転写することを特徴とする請求
項１及至４記載の放電加工装置。6. The tool electrode according to claim 1, wherein the electrode is a tool electrode pre-machined into a desired three-dimensional shape, and the three-dimensional shape of the tool electrode is transferred to the workpiece. Electric discharge machine. 【請求項７】 前記電極がワイヤ電極であり、前記被加
工物が板状導電体である放電加工装置において、前記ワ
イヤ電極と板状導電体の面方向とを直交させるととも
に、前記ワイヤ電極と前記板状導電体の相対位置を変化
させるための少なくとも２軸以上の軸移動手段を備えた
ことを特徴とする請求項１及至４記載の放電加工装置。7. An electric discharge machine in which the electrode is a wire electrode and the workpiece is a plate-shaped conductor, and the wire electrode and the plate-shaped conductor are made to intersect at right angles with each other, and 5. The electric discharge machine according to claim 1, further comprising at least two or more axis moving means for changing the relative position of the plate-shaped conductor.