JP2006130653A - Electrical discharge machining device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrical discharge machining device certainly performing parallel discharging and enhancing electrical discharge machining speed. <P>SOLUTION: An electrical discharge machining electrode 14 is constituted by a layered anisotropy conductor 11, a resistance body 12 and an electricity feeding body 13. The layered anisotropy conductor 11 is a member in which thin plates of metal coated with an insulation coating film are superposed and press-fitted. In the conductor, a conductive layer and a non-conductive layer are alternately superposed in a layered shape, it has anisotropy conductivity that conductivity in a direction parallel to the non-conductive layer is outstandingly higher than conductivity in a direction crossing the non-conductive layer and an opposed area of the respective conductive layers to a work is 0.1 mm<SP>2</SP>or more. The resistance body 12 is connected to a laminated layer crossing end surface 11c of the layered anisotropy conductor 11 and the electricity feeding body 13 is further connected to the resistance body 12. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electric discharge machining apparatus.

As one of the measures for improving the machining speed in the electric discharge machining, it is conceivable to simultaneously generate a plurality of electric discharges (hereinafter referred to as parallel discharge). The method for realizing this parallel discharge can be found in the countermeasure against the deterioration of the machined surface roughness in the finishing area of a large area.

For example, Japanese Patent Application Laid-Open No. 61-71920 discloses a method for improving the surface roughness in a finishing area having a large area by using a resistor as the surface of the electrode (hereinafter referred to as a resistor electrode method). Has been.
FIG. 11 is a structural diagram showing electrodes in the resistor electrode method. In the figure, an electrode is formed by adhering a resistor 1 made of a thin silicon plate having a thickness of 1.5 mm and a power feeder 2 made of copper with a conductive adhesive.

  The principle of the resistor electrode method is that the stray capacitance formed between the electrode and the workpiece (hereinafter referred to as the machining gap) is divided by the resistance inherent in the resistor 1 placed on the electrode surface to obtain a distributed constant state. None, to reduce the amount of energy input from the stray capacitance to the point of occurrence of discharge in the same manner as in small area machining, thereby preventing deterioration of machined surface roughness in large area machining. However, in a small amount, in the above disclosed example, if the electrode surface is a resistor, a potential gradient is generated in the electrode, and thus multiple discharges may occur simultaneously (that is, parallel discharge is realized). However, there are problems as described below.

  In addition, as electric discharge machining methods similar to the above, there are JP-A-58-186532 and JP-A-62-84920, and the surface is roughened in a finishing area having a large area by dividing the electrode into columns. A method for improving the degree (hereinafter referred to as a divided electrode method) is disclosed.

  FIG. 12 is a structural view showing electrodes in the divided electrode method, and FIG. 13 is a perspective view showing the whole electrodes in the divided electrode method. 11 that are the same as or equivalent to those in FIG. 12 and 13, 3 is an insulator, and 4 is a columnar member made of a low resistance material such as copper.

  The principle of the divided electrode method is that, as shown in FIG. 12, a plurality of columnar members 4 insulated from each other by the insulator 3 are connected to the power feeder 2 through the resistor 1, so that the entire electrode is shown in FIG. It is to form a bundle of columnar electrodes, and to reduce the stray capacitance formed in the machining gap by dividing it as small as in the small area machining, thereby preventing deterioration of the machined surface roughness in the large area machining. However, there is no mention of parallel discharge in the disclosed example of the split electrode method.

  Also, in the literature (see Precision Engineering Journal vol. 53, No. 1, P124-130) that summarizes the electric discharge machining methods of the resistor electrode method and the split electrode method, the resistor electrode method is used for parallel discharge. Only a few are mentioned, and there is no mention in the split electrode method. The parallel discharge in the case of this document has the following problems.

JP-A-61-71920 JP 58-186532 A JP 62-84920 A Journal of Japan Society for Precision Engineering (vol. 53, No. 1, P124-130)

  As described above, in the resistor electrode method, in order to solve the problem that the finished surface roughness is deteriorated in large-area finishing, the stray capacitance formed in the machining gap is divided into small parts by resistance, and thus, when the small-area machining is performed. The main objective is to obtain the same finished surface roughness. In other words, a large-area finishing process is performed by limiting the stray capacitance that contributes to machining when a discharge occurs to the capacitance that is formed near the discharge occurrence point (generally within a circle with a radius of about several hundred microns) by a resistor placed on the electrode surface. The effect of stray capacitance formed in the machining gap, which is sometimes problematic, is made as small as possible.

Therefore, in this case, since the amount of processing due to the stray capacitance formed in the processing gap is negligibly small, it may be considered that all the energy provided for processing is supplied in a pulse form from the processing power source. For this reason, the energy provided for machining can be considered to be almost constant regardless of whether or not parallel discharge occurs, so that when parallel discharge occurs, the machining current supplied from the machining power source is at multiple discharge points. There is a problem that the electrical discharge machining speed is not improved even with parallel discharge.
Further, the resistor electrode method has a problem in that when a large machining current such as rough machining flows, the electrode generates heat due to resistance heating caused by the machining current, so that the electrode is consumed greatly.

Moreover, in the electrode by the divided electrode method, there was a problem that practically no parallel discharge occurred. This is because, in electrical discharge machining, the higher the scrap density, the longer the distance between the electrodes that can generate electrical discharge, so that once electrical discharge begins, electrical discharge is continuously generated in the vicinity, as described in the above document. For example, in a divided electrode in which columnar members having a side of about 10 mm are bound, it is considered that discharge is continuously generated in a specific columnar member where discharge has started. In addition, in the divided electrode method, it is surmised that it is due to this problem that there is no mention of parallel discharge in the above-mentioned document.
Furthermore, the divided electrode method has a problem that the structure of the electrode is complicated.

The present invention has been made to solve the above-described problems, and a first object is to obtain an electric discharge machining apparatus capable of improving the electric discharge machining speed.
The second object is to obtain an electric discharge machining apparatus capable of suppressing electrode consumption.
Furthermore, the third object is to obtain an electric discharge machining apparatus capable of reliably performing parallel discharge and having a simple electrode structure.

The electric discharge machining apparatus according to the present invention is an electric discharge machining apparatus including an electric discharge machining electrode facing a workpiece with a machining gap interposed therebetween, wherein the electric discharge machining electrode includes a thin plate-shaped conductive layer and a defective conductive layer. Are laminated alternately, a layered anisotropic conductor, a resistor connected to the laminated transverse end face of the layered anisotropic conductor, and a power supply connected to the resistor, The area facing the workpiece is 0.1 square mm or more.

  Since the present invention is configured as described above, the following effects can be obtained.

  An electric discharge machining apparatus including an electric discharge machining electrode facing a workpiece via a machining gap, and a layered anisotropic conductor in which thin plate-like conductive layers and defective conductive layers are alternately laminated, and An electrode for electric discharge machining is composed of a resistor connected to the laminated transverse end face of the layered anisotropic conductor and a power supply connected to the resistor, and the area of the conductive layer facing the workpiece is 0. Although the thickness of each conductive layer is thin because the thickness is not less than 1 square mm, the facing surface to the workpiece is elongated and the facing area that can be regarded as the same capacitor can be widened. For this reason, the capacitance formed in the machining gap with the workpiece becomes an aggregate of minute capacitors connected in parallel with each other via a resistor, and each capacitor performs an electric discharge machining. Because it has sufficient capacitance and is close enough to the distance where parallel discharge can be generated, it is possible to perform electrical discharge machining reliably in parallel and for simple electrical discharge machining. It becomes possible to improve the electric discharge machining speed by using the electrode.

Embodiment 1 FIG.
1 is a perspective view showing the structure of an electrode for electric discharge machining in Embodiment 1 of the present invention, FIG. 2 is an equivalent circuit diagram showing the principle of electric discharge of the electric discharge machining apparatus in FIG. 1, and FIG. 3 is for electric discharge machining in FIG. It is a block diagram which shows schematic structure of the electrical discharge machining apparatus provided with the electrode. In FIG. 1, an electrode 14 is composed of a layered anisotropic conductor 11, a resistor 12, and a power feeder 13. The layered anisotropic conductor 11 is a member obtained by stacking and press-bonding metal thin plates made of copper or the like whose surface is coated with an insulating coating made of ceramics such as alumina or enamel, and a conductive layer and a defective conductive layer in layers. Are alternately stacked, and the conductivity in the direction parallel to the defective conductive layer has an anisotropic conductivity significantly higher than the conductivity in the direction crossing the defective conductive layer.

  In the following description, for the sake of explanation, a surface parallel to the conductive layer and the defective conductive layer is referred to as a laminated surface 11a, and of the end surfaces of the layered anisotropic conductor 11, an end surface parallel to the laminated surface 11a is referred to as a laminated parallel end surface 11b. An end face that crosses the laminated surface 11a is referred to as a laminated transverse end face 11c. Further, in the drawing, as shown in FIG. 1, a plurality of laminated surfaces 11a are drawn on the laminated transverse end surface 11c to distinguish them from the laminated parallel end surfaces 11b.

  For the production of the layered anisotropic conductor 11, for example, if a thin metal sheet coated with an insulating film is supplied to a rapid prototyping apparatus using a method of cutting and laminating a thin sheet material, three-dimensional CAD data is provided. Thus, an electrode having a desired shape can be easily manufactured directly. The thickness of each conductive layer is preferably 1 mm or less, and is satisfactory if it is 100 μm or less. Further, it is desirable that the thickness of the defective conductive layer is as thin as possible, and the thickness is approximately equal to or less than the thickness of the conductive layer.

The resistor 12 is made of carbon or nickel chrome alloy having electric resistance connected to the laminated transverse end face 11c of the layered anisotropic conductor 11, and for example, a thin plate having electric resistance is laminated on the laminated transverse end face 11c. It is configured by pressure bonding to the conductor 11 or forming an electric resistance thin film by a vacuum process.
The power feeder 13 is made of conductive copper or the like connected to the resistor 12, and is connected to the resistor 12 by pressure bonding or thin film formation as in the case of the resistor 12.

  With such a configuration, each conductive layer in the layered anisotropic conductor 11 is connected to the power feeder 13 via the resistor 12. A desirable value of the electrical resistance value from the power supply body 13 to the conductive layer varies depending on various factors, but is preferably approximately 10Ω to 10 kΩ.

  Next, characteristics when the electrode 14 having the above structure is used will be described with reference to FIG. In electric discharge machining, since the electrode and the workpiece are opposed to each other with a minute gap, a capacitor with a stray capacitance is formed in the machining gap as described above. When the electrode 14 is used, the respective conductive layers in the layered anisotropic conductor 11 are connected in parallel to each other through the electric resistance in the resistor 12 as in the equivalent circuit shown in FIG. Will form an accumulator.

  Therefore, if a voltage is applied between the electrode 14 and the workpiece 15, each capacitor is charged and then discharge occurs in the machining gap. Since each of the capacitors is connected in parallel with each other via a resistor, the voltage between the terminals has a different value. That is, even when a discharge occurs in a certain capacitor, parallel discharge can be generated because the voltage between the terminals of the capacitor sufficiently away from the discharge position hardly changes.

  The difference between the first embodiment and the conventional resistor electrode method will be described next. In the case of the resistor electrode method, as shown in FIG. 11, the electrode is configured by adhering a resistor 1 made of a thin silicon plate and a power feeder 2 made of copper with a conductive adhesive. Thus, the stray capacitance formed in the machining gap between the electrode and the workpiece is divided into small pieces by the resistance. In other words, a large-area finishing process is performed by limiting the stray capacitance that contributes to machining when a discharge occurs to a capacitor that is formed near the discharge occurrence point (generally within a circle with a radius of about several hundred microns) by a resistor placed on the electrode surface. The effect of stray capacitance formed in the machining gap, which is sometimes problematic, is made as small as possible.

  Therefore, in this case, since the amount of processing due to the stray capacitance formed in the processing gap is negligibly small, it may be considered that all the energy provided for processing is supplied in a pulse form from the processing power source. For this reason, the energy provided for machining can be considered to be almost constant regardless of whether or not parallel discharge occurs, so that when parallel discharge occurs, the machining current supplied from the machining power source is at multiple discharge points. The electric discharge machining speed is not improved even with parallel discharge.

  On the other hand, in the present invention, as shown in FIG. 1, a layered anisotropic conductor 11 in which a conductive layer and a defective conductive layer are stacked, and a laminated transverse end face 11 c of the layered anisotropic conductor 11 are connected. An electrode 14 including a resistor 12 having electrical resistance and a conductive power supply 13 connected to the resistor 12 is presented. In this case, since the electrical resistance between two points in the same conductive layer is almost zero, each conductive layer can be regarded as one capacitor, so the range that can be regarded as one capacitor is the discharge occurrence point. The point that can be regarded as a single capacitor as long as the same conductive layer is used without depending on the distance from is a point that is greatly different from the resistor electrode method. Since each conductive layer is thin but the surface facing the workpiece 15 is elongated, the opposing area that can be regarded as the same capacitor can be made wider than that of the resistor electrode method. It is possible to increase the capacitance so that the contribution of processing by the capacitor formed by can not be ignored.

  That is, the stray capacitance formed in the machining gap with the workpiece 15 is a target to be excluded in the resistor electrode method, and the machining mainly depends on the pulse current supplied from the machining power source. However, in the present invention, the stray capacitance is positively utilized, and the current supplied from the machining power source is stored once in each capacitor formed by the stray capacitance and then used for processing. Therefore, each conductive layer is formed. Parallel electric discharge machining by discharging of the battery can be realized, and the electric discharge machining speed can be improved by using the electrode 14 having a simple structure. In the case of the present invention, the current supplied from the machining power supply is a charging current to each capacitor and is not used for direct discharge as in the resistor electrode method. It is not necessary to be in the shape, and supply is possible with an arbitrary current waveform such as a steady current waveform.

  Next, differences between the first embodiment of the present invention and the conventional divided electrode method will be described. In the case of the divided electrode method, as shown in FIG. 12, a plurality of columnar members 4 insulated from each other by the insulator 3 are connected to the power feeder 2 via the resistor 1, whereby the entire electrode is formed as shown in FIG. As shown in FIG. 4, the columnar electrode is formed into a bundle, and the stray capacitance formed in the processing gap is divided and reduced as small as in the small area processing. However, as already described, once electrical discharge occurs in electrical discharge machining, it tends to occur continuously around it, and each columnar member is close enough to several hundred microns, for example, to generate parallel discharge. It is necessary to install it. However, in order to bring the columnar members close to each other, it is necessary to make the respective columnar members thinner. Therefore, the opposing area between each columnar member and the work must be reduced, and each columnar member is formed. Since the stray capacitance to be reduced also becomes small, the charge stored in the stray capacitance hardly contributes to the processing.

  That is, the columnar member 4 is sufficiently thick in order to store and process the floating capacity formed by each columnar member facing the workpiece 15, and it is necessary to face the workpiece 15 in a wide area of, for example, 1 square mm or more. There is. On the other hand, in order to generate parallel discharge, the columnar member 4 is sufficiently thin and needs to be adjacent to another columnar member at a distance of, for example, about several hundred microns or less, and it is very difficult to achieve both. Therefore, in the split electrode method using a columnar member having a thickness of several mm square or more where an electrode can actually be manufactured, the discharge is continuously generated in a specific columnar member where the discharge has started. It hardly occurs.

  However, in the case of the present invention, as described above, each conductive layer is thin and long, so that each conductive layer has a sufficient facing area to form a capacitance large enough to contribute to processing. The other conductive layers can be adjacent to each other at a distance where parallel discharge can be sufficiently generated. For example, if the distance between each conductive layer is about several hundred microns and a facing area of about 1 square mm or more is to be realized, each conductive layer and the workpiece should be opposed over a length of about several mm. Good. In this way, in the present invention, it becomes possible to place a capacitor having a large capacity close to each other, so that it is not a situation in which a discharge occurs substantially in only one capacitor as in the split electrode method, Parallel electric discharge machining can be realized reliably, and the electric discharge machining speed can be improved by using the electrode 14 having a simple structure.

  Next, the configuration and operation of the electrical discharge machining apparatus including the electrical discharge machining electrode according to Embodiment 1 of the present invention will be described with reference to FIG. The electrode 14 having the structure described above is mounted on the main shaft 16 of the electric discharge machining apparatus, and the work 15 is installed in a machining tank 17. Here, if the opposing area of each conductive layer in the electrode 14 and the work 15 is too small, the stray capacitance contributing to the processing becomes too small as in the case of the resistor electrode. The desirable facing area varies depending on the distance between the electrode 14 and the work 15, but is preferably 0.1 square mm or more, and is satisfactory if it is 1 square mm or more. That is, if the thickness of the conductive layer is about 100 μm, it can be said that the conductive layer and the workpiece are facing each other over a length of 10 mm or more.

  The processing tank 17 is filled with a processing liquid 18. The machining power source 19 is a constant voltage power source having a sufficient current supply capability, and is connected to the power supply body 13 and the work 15 provided on the electrode 14. The control device 20 controls the position of the electrode 14 via the main shaft 16 so that the distance between the electrode 14 and the work 15 is constant. As the control method, for example, a known method such as controlling the electrode position so that the machining current is constant can be adopted. That is, the charging current to the capacitor formed in the machining gap is measured using a current detector such as a Hall element or current transformer, or the voltage across the terminals of a shunt resistor inserted in series in the charging circuit. The position of the electrode 14 may be controlled so as to decrease the distance between the electrode 14 and the work 15 when the value falls below a preset value and increase when the value exceeds the value. The machining current is charged from the machining power source 19 to the individual capacitors formed between the respective conductive layers and the work 15 via the power supply 13 and the resistor 12, and then subjected to machining by discharge generated simultaneously in parallel. It is done.

  In the example of the first embodiment, the machining power supply 19 supplies a constant voltage. However, a normal electric discharge machining apparatus or a power supply that applies a pulsed voltage as in the resistor electrode method is used. In this case, the effect of suppressing the occurrence of arc discharge can be expected. In addition, if a power supply that can change the voltage value to be applied is used, it is convenient because machining with various surface roughnesses can be realized and it can be used for avoidance control of abnormal discharge states.

  Moreover, in the example of the first embodiment, the configuration is such that the charging current to the capacitor is measured and the position of the electrode 14 is controlled. However, since the output voltage value of the machining power source 19 is known, the charging power supply circuit of the capacitor is in series. If a machining power source with a high output impedance is used, a charging current value can also be obtained from the potential difference between the power supply body 13 and the work 15, so the measurement of the charging current value is omitted, and this power supply body Needless to say, the position of the electrode 14 may be controlled based on the potential difference between the workpiece 13 and the workpiece 15. That is, a known control for controlling the position of the electrode 14 to increase the distance between the electrode 14 and the work 15 when the voltage between the power supply body 13 and the work 15 is lower than a preset value, and to decrease when the voltage is higher. The method can be used.

  In the example of the first embodiment, the layered anisotropic conductor 11 of the thin metal plate coated with the insulating film is illustrated as the layered anisotropic conductor 11, but the defective conductive layer needs to be a complete insulator. Instead, an electric resistor may be used, and the same effects as described above can be achieved. In this case, an electrode can be realized at low cost. However, since the resistance value needs to be large enough to cause a significant potential difference between different laminated surfaces, it is desirable to employ a material having a resistance value of 100Ω or more per 1 cm of the laminated thickness.

  In the first embodiment, the resistor and the power feeder are formed on the upper surface of the electrode. However, these positions may be anywhere on the stacked transverse end surface 11c that crosses the stacked surface, for example, formed on the side surface of the electrode. May be.

  In the first embodiment, the shape of the power feeding body 13 is not particularly mentioned. However, the larger the processing volume for each conductive layer per unit electrode moving distance in the processing progress direction, the larger the power feeding facing the conductive layer. If the total sum of the widths of the bodies 13 is set to be large, the charge resistance to the capacitor decreases as the machining amount increases, so that the discharge frequency can be increased. Accordingly, since the discharge frequency per unit processing volume is made uniform, there is an advantage that discharge is not concentrated and generated at a high frequency in a narrow range, and abnormal wear of the electrode is prevented.

  For example, as in the case of normal rough machining, when the machining progress direction is vertically downward, the width of the power feeding body is increased in a portion connected to a conductive layer having a large electrode projection area in the vertical direction. For this purpose, as shown in FIG. 4, the electrode 14e may be cut along a horizontal plane, and the resistor 12e and the power supply 13e may be formed on the entire cut surface. In addition, for example, in the case of rocking machining in the finishing machining stage, when the machining in the horizontal direction is the main and the projected area in the machining progress direction of any conductive layer is almost equal, the shape of the power feeder is the laminated surface The width in the direction parallel to the width may be constant.

  As described above, according to the first embodiment, the layered anisotropic conductor in which the conductive layers and the defective conductive layers are alternately stacked, and the resistor connected to the stacked transverse end face of the layered anisotropic conductor, Since the electrode for electric discharge machining is composed of the power supply body connected to the resistor, each conductive layer is thin, but the surface facing the workpiece is long and narrow, so the same capacitor The facing area that can be considered as can be widened. For this reason, the capacitance formed in the machining gap with the workpiece becomes an assembly of minute capacitors that are connected in parallel with each other via a resistor, and each capacitor has sufficient capacitance to perform electric discharge machining. Since it has a capacitance and is close to a distance where parallel discharge can be sufficiently generated, electric discharge machining can be performed reliably in parallel, and an electric discharge machining electrode with a simple structure can be formed. It becomes possible to improve the electric discharge machining speed.

  Further, since the defective conductive layer of the layered anisotropic conductor is made of an electric resistor, the electrode can be manufactured at low cost.

  Furthermore, the larger the processing volume for each conductive layer per unit electrode movement distance in the processing progress direction, the larger the total sum of the widths of the power feeding bodies facing the conductive layer, so that the portion with the larger processing amount has a higher discharge frequency. As a result, it is possible to prevent abnormal consumption of the electrodes.

Embodiment 2. FIG.
5 is a perspective view showing the structure of an electric discharge machining electrode according to Embodiment 2 of the present invention, and FIG. 6 is a block diagram showing a schematic configuration of an electric discharge machining apparatus provided with the electric discharge machining electrode of FIG. 5 and 6, the same reference numerals as those in FIGS. 1 to 3 indicate the same or corresponding parts, and the description thereof is omitted. In FIG. 5, the layered anisotropic conductor 11, the resistor 12, the power feeder 13, the dielectric 21, and the grounding body 22 constitute an electrode 24. The dielectric 21 is a dielectric member installed on the laminated transverse end face 11c of the layered anisotropic conductor 11, and is formed of, for example, a thin film of titanium oxide or barium titanate. The grounding body 22 is a conductive member installed on the dielectric 21 and is formed by pressure bonding, thin film formation, or the like, similar to the power feeding body 13.

  Next, the operation will be described. As shown in FIG. 6, the electrical discharge machining apparatus according to the second embodiment and the first embodiment are different in that the grounding body 22 and the work 15 are connected by a wire or the like. In the first embodiment, the processing is performed by the stray capacitance formed between the respective conductive layers facing each other via the machining liquid 18 and the workpiece 15, but in the second embodiment, in addition to this, the respective conductive layers are grounded. The capacitance formed between the bodies 22 also contributes to the processing. Here, various materials can be used for the dielectric 21 existing between each conductive layer and the grounding body 22. For example, if a high dielectric constant material such as the barium titanate is used, the working liquid is reduced. Therefore, it is possible to easily obtain a capacitance several thousand times larger in the same area than when facing each other.

  Further, since the laminated transverse end face 11c forming the dielectric 21 exists not only on the upper surface of the electrode but also on the side face, for example, it is possible to provide many fine slits on the surface of the laminated transverse end face 11c. The opposing area between the laminated transverse end face 11c and the grounding body 22 can be remarkably increased by a method such as forming the dielectric 21 on all the surfaces of the fine slits. Obtaining a capacitance can be realized.

  Therefore, according to the second embodiment, the conductive grounding body 22 is provided on the laminated transverse end face 11 c of the layered anisotropic conductor 11 via the dielectric 21, and the grounding body 22 is connected to the work 15. As a result, the electrostatic capacity formed in the machining gap between the electrode 24 and the workpiece is further increased as compared with the case of the first embodiment. It becomes possible to further improve the electric discharge machining speed by using the electric discharge machining electrode having the structure.

  In the case of the first embodiment, if the distance between the electrode 14 and the workpiece 15 changes, the capacitance used for processing changes, but in the case of the second embodiment, the grounding body 22 and the layered anisotropic are changed. Since the capacitance value formed between the laminated transverse end faces 11c of the conductive conductor 11 is not affected by the machining gap length, the machining surface has a uniform surface roughness that is not affected by the facing area between the electrode 24 and the workpiece. Can be realized.

  In the second embodiment, the dielectric body and the grounding body are formed on the side surface of the electrode. However, these positions may be anywhere on the crossing end surface crossing the stacking surface, for example, on the top surface of the electrode. Also good. As for the shape of the power feeding body 13, as in FIG. 4, the larger the processing volume for each conductive layer per unit electrode movement distance in the processing progress direction, the greater the total width of the power feeding body 13 facing the conductive layer. It may be set larger, and the same effect as the case of Embodiment 1 is produced.

Embodiment 3 FIG.
7 is a perspective view showing the structure of an electric discharge machining electrode according to Embodiment 3 of the present invention, and FIG. 8 is a block diagram showing a schematic configuration of an electric discharge machining apparatus provided with the electric discharge machining electrode of FIG. 7 and 8, the same reference numerals as those in FIGS. 1 to 3 denote the same or corresponding parts, and the description thereof is omitted. In FIG. 7, the layered anisotropic conductor 11, the resistor 12, and the power feeding body 33 constitute an electrode 34. The power feeding body 33 is composed of a first power feeding body 33a and a second power feeding body 33b, and is connected to the resistor 12 at two locations separated from each other in a direction crossing the laminated surface 11a of the layered anisotropic conductor 11, It consists of copper etc. which have electroconductivity, and is formed in the resistor 12 by pressure bonding, thin film formation, etc.

  As shown in FIG. 8, the first electric power feeder 33a and the second electric power feeder 33b are processed through the electric power supply lines 35a and 35b in the electric discharge machining apparatus according to the third embodiment and the first embodiment. It differs from the first embodiment in that a first current detector 36a and a second current detector 36b connected to the power source 19 and connected to the control device 20 are provided on the power supply lines 35a and 35b. .

Next, the operation will be described. Since the mechanism for generating the parallel discharge is the same as in the first embodiment, the description thereof is omitted.
In general, when an electrode material having a relatively high electric resistance such as graphite is used, it is known that a discharge generation position can be specified by providing a plurality of feeding points and measuring each machining current.
The layered anisotropic conductor 11 has a low electric resistance in a direction parallel to the laminated surface 11a, but has an extremely high electric resistance in a direction crossing the laminated surface 11a. Therefore, when the charging current flows in the direction crossing the laminated surface 11 a, it flows not in the layered anisotropic conductor 11 but in the resistor 12.

  Therefore, as in the case of the graphite electrode, by measuring the feeding currents flowing through the first and second feeding bodies 33a and 33b using the first and second current detectors 36a and 36b, respectively, It is possible to detect which capacitor is charged between feeding points. For this reason, based on a known method for controlling the electrode position so that the machining current is constant as described in the first embodiment, or on the potential difference between the power feeder and the workpiece as described in the first embodiment. In addition to the known method of controlling the position of the electrodes, if it can be determined from the outputs of the two current detectors 35a and 35b that the charging current is concentrated on a specific capacitor, it is considered that a short circuit has occurred. Control to separate the electrode and the workpiece can be added, and damage to the processed surface of the workpiece 15 can be avoided.

  In the above embodiment, two power feeding bodies are provided. However, power feeding bodies may be provided at three or more places.

  As described above, according to the third embodiment, the power feeding body is composed of at least two power feeding bodies, and the power feeding bodies are separated from each other in the direction crossing the laminated surface of the layered anisotropic conductors to become the resistor bodies. By including a current detector that is connected and measures the current flowing to each power supply body, it is possible to determine whether or not the charging current is concentrated on a specific capacitor, so that damage to the workpiece surface can be avoided.

Embodiment 4 FIG.
9 is a perspective view showing the structure of an electric discharge machining electrode according to Embodiment 4 of the present invention, and FIG. 10 is a perspective view showing another electric discharge machining electrode according to Embodiment 4 of the present invention. 9 and 10, the same reference numerals as those in FIG. 1 denote the same or corresponding parts, and the description thereof is omitted. 9 and 10, the layered anisotropic conductor 11, the resistor 12, and the power feeding body 43 constitute an electrode 44. The power feeding body 43 is made of conductive copper or the like, and is composed of a first power feeding body 43a and a second power feeding body 43b.

  The first power feeding body 43a and the second power feeding body 43b are separated from each other in a direction parallel to the laminated surface 11a, and are opposed to each conductive layer of the layered anisotropic conductor 11 and each of the two power feeding bodies. The area difference or ratio is set differently for each conductive layer. For example, as shown in FIG. 9, the first power feeding body 43a has a constant width in the direction parallel to the laminated surface 11a, and the second power feeding body 43b has a width in the direction parallel to the laminated surface 11a. This can be realized by gradually increasing the installation.

  The electric discharge machining apparatus according to Embodiment 4 is configured in the same manner as in FIG. For example, the first power supply body 43a and the second power supply body 43b are connected to the machining power supply 19 via power supply lines 35a and 35b, and the first power supply lines 35a and 35b are connected to the control device 20. Current detector 36a and second current detector 36b are provided.

  Next, the operation will be described. Since the mechanism for generating the parallel discharge is the same as in the first embodiment, the description thereof is omitted. In the case of this embodiment, current flows in the thickness direction of the resistor 12 from the first and second power feeding bodies 43a and 43b to the respective conductive layers. Therefore, the charging resistance to the capacitor formed between each conductive layer and the work 15 is inversely proportional to the facing area between each conductive layer and the first and second power feeding bodies 43a and 43b.

  Moreover, since the charging current to each capacitor is inversely proportional to the charging resistance, the charging current flows in proportion to the facing area. As is apparent from the already described power supply installation mode, the difference or ratio of the opposing areas of the conductive layer and the first and second power supply bodies 43a and 43b is set differently for each conductive layer. Therefore, the difference or ratio of the charging currents flowing through the first and second power feeding bodies 43a and 43b is also different for each conductive layer. Therefore, by measuring the charging currents flowing through the first and second power feeding bodies 43a and 43b individually as in the third embodiment, it is possible to detect which capacitor is charged. Therefore, it is possible to avoid damage to the work surface of the workpiece.

  In the fourth embodiment, the relationship between the difference or ratio between the opposing areas of each conductive layer and each of the two power feeders and the position of each conductive layer is not particularly mentioned. Is a monotonous increase or decrease with respect to the position of each conductive layer, and more preferably, it is changed so as to change in a linear function relationship as shown in FIG. Has the advantage of becoming easier.

Furthermore, since the charging resistance in the fourth embodiment is determined by the sum of the opposing areas of each conductive layer and the two power feeding bodies 43a and 43b, the sum of the opposing areas is the same as that of each conductive layer in the first embodiment. This corresponds to the area facing the power feeder. Therefore, as in the first embodiment, the larger the processing volume for each conductive layer per unit electrode movement distance, the greater the processing amount if the shape is such that the sum of the widths of the power feeding bodies facing the conductive layer is larger. Since the discharge frequency can be increased as much as possible, abnormal wear of the electrodes can be prevented.
In the above embodiment, two power feeding bodies are provided. However, three or more power feeding bodies may be provided, and two of them may be used as necessary.

  As described above, according to the fourth embodiment, the power feeding body includes at least two power feeding bodies, and the power feeding bodies are separated from each other in a direction parallel to the laminated surface 11a of the layered anisotropic conductor 11. In addition, the difference or ratio of the opposing areas of the conductive layers of the layered anisotropic conductor 11 and the power feeders is different for each conductive layer, and the current flowing to each power feeder is connected to the resistor. By providing the current detector to be measured, it is possible to determine whether or not the charging current is concentrated on a specific battery, so that damage to the work surface of the workpiece can be avoided.

  In addition, since the configuration is such that the difference or ratio of the facing area between each conductive layer and each power supply body changes in a linear function relationship with respect to the position of each conductive layer, the process of specifying the charging position from the current detector output Becomes easier.

It is a perspective view which shows the structure of the electrode for electrical discharge machining in Embodiment 1 of this invention. It is an equivalent circuit diagram which shows the principle of the discharge of the electric discharge machining apparatus of FIG. It is a block diagram which shows schematic structure of the electrical discharge machining apparatus provided with the electrode for electrical discharge machining of FIG. It is a perspective view which shows the structure of the other electrode for electrical discharge machining in Embodiment 1 of this invention. It is a perspective view which shows the structure of the electrode for electrical discharge machining in Embodiment 2 of this invention. It is a block diagram which shows schematic structure of the electrical discharge machining apparatus provided with the electrode for electrical discharge machining of FIG. It is a perspective view which shows the structure of the electrode for electrical discharge machining in Embodiment 3 of this invention. It is a block diagram which shows schematic structure of the electrical discharge machining apparatus provided with the electrode for electrical discharge machining of FIG. It is a perspective view which shows the structure of the electrode for electrical discharge machining in Embodiment 4 of this invention. It is a perspective view which shows the other electrode for electrical discharge machining in Embodiment 4 of this invention. It is a structural diagram which shows the electrode in the conventional resistor electrode method. It is a structural diagram which shows the electrode in the conventional split electrode method. It is a perspective view which shows the whole electrode in the conventional split electrode method.

Explanation of symbols

11, 11e Laminated anisotropic conductor 11a Laminated surface 11b Laminated parallel end surface 11c Laminated transverse end surface 12, 12e Resistors 13, 13e, 33a, 33b, 43a, 43b Electric power feeders 14, 14e, 24, 34, 44 For electric discharge machining Electrode 15 Workpiece 21 Dielectric 22 Grounding body 36a, 36b Current detection means

Claims (8)

An electric discharge machining apparatus including an electric discharge machining electrode facing a workpiece with a machining gap interposed therebetween, wherein the electric discharge machining electrode has a layered structure in which thin plate-like conductive layers and defective conductive layers are alternately laminated. An area of the conductive layer facing the workpiece, comprising a isotropic conductor, a resistor connected to the laminated transverse end face of the layered anisotropic conductor, and a power feeding body connected to the resistor Is an electric discharge machining apparatus characterized by being 0.1 square mm or more. 2. The electric discharge machining apparatus according to claim 1, wherein a conductive grounding body is provided on a crossing end face of the layered anisotropic conductor via a dielectric, and the grounding body is connected to a workpiece. 3. The electric discharge machining apparatus according to claim 1, wherein the defective conductive layer of the layered anisotropic conductor is made of a non-conductive material. 3. The electric discharge machining apparatus according to claim 1, wherein the defective conductive layer of the layered anisotropic conductor is made of an electric resistor. The power feeding body includes at least two power feeding bodies, and is provided with a current detection unit that is connected to a resistor apart from each other in a direction transverse to the laminated surface of the layered anisotropic conductors and measures a current flowing to each of the power feeding bodies. The electric discharge machining apparatus according to any one of claims 1 to 4, wherein The power feeding body is composed of at least two power feeding bodies, the power feeding bodies are separated from each other in a direction parallel to the laminated surface of the layered anisotropic conductor, and each conductive layer of the layered anisotropic conductor A difference or ratio of a facing area with each of the power feeding bodies is connected to the resistor in a state that is different for each of the conductive layers, and includes a current detection unit that measures a current flowing to each of the power feeding bodies. The electric discharge machining apparatus according to claim 1. The larger the processing volume for each conductive layer per unit electrode movement distance in the processing progress direction, the larger the total sum of the widths of the respective conductive layers in the length direction of the power supply body facing the respective conductive layers is set. The electric discharge machining apparatus according to claim 1, wherein the electric discharge machining apparatus is provided. The constitution is such that the difference or ratio of the opposing areas of the respective conductive layers forming the layered anisotropic conductor and the respective power feeders changes in a linear function relationship with respect to the position of each of the conductive layers. Item 7. The electric discharge machining apparatus according to Item 6.

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