KR19990046308A - Electro-discharge machining way - Google Patents

Abstract

The present invention relates to an electric discharge machining in which the workpiece is processed in the same manner as the shape of the electrode because the workpiece is placed in the processing liquid so that the electrode is brought close to each other.

In the three-dimensional electric discharge machining, it provides a method to determine the optimum electric discharge machining conditions for the case of the direct discharge processing and the electric discharge machining of the pre-processed object without pre-processing the workpiece, and the electric discharge machining time can be easily estimated accordingly. It is an object of the present invention to provide a process capable of processing at an optimum electric discharge machining condition.

Therefore, in order to achieve the above object, in the three-dimensional discharge machining, since the discharge machining areas according to the machining parts are different from each other, the method of first obtaining the discharge machining area from the curved surface of the tool electrode and the NC code for machining the tool electrode Z-Map modeling is to find the discharge machining area and the tooling electrode to calculate the discharge machining area from the data measured by a three-dimensional measuring instrument.

Description

Determination of Optimal Discharge Machining Conditions and Estimation of Discharge Machining Times in Discharge Machining {ELECTRO-DISCHARGE MACHINING WAY}

The present invention relates to an electric discharge machining in which the workpiece is processed in the same manner as the electrode shape by disposing the workpiece in the processing liquid so that the electrode is close to each other. In particular, the shape of the workpiece to be processed is three-dimensionally discharged. Method for determining discharge processing conditions and estimating discharge processing time in electric discharge machining, which enables to calculate the optimal electric discharge machining condition and electric discharge machining time easily in order to make planned production, improve productivity and improve product quality. will be.

In general, as shown in FIG. 1, the electric discharge machining is performed by using a conductive material such as copper or graphite as the tool electrode 1, and widely used to process conductive materials such as steel and cemented carbide. In this discharge processing, when a pulse voltage of about 60 V to 300 V is applied between the pore electrode 1 and the workpiece 3 separated by the insulating liquid 2, the insulating state is destroyed and spark discharge occurs. In this case, a part of the electrode 1 is consumed by the heat generated and the workpiece 3 is processed into a product having the same shape as the tool electrode 1 by using this consumption phenomenon.

Therefore, the discharge machining method is a method of using the thermal energy generated when the discharge is generated by artificially setting the discharge occurrence phenomenon as follows.

One). Arc column formation by discharge and local melting by discharge heat energy (about 5000K or more).

2). Generation of vaporization explosive force of the working liquid and the vaporization of the molten part accordingly.

3). The generation of minute discharge traces on the workpiece due to cooling, solidification, deionization between the melt and the like to the processing liquid.

Therefore, if the above process is repeated at a high speed (1 ~ several kHz), processing proceeds by accumulation of discharge traces, and if the distance between the poles increases and the process progresses, the servo mechanism maintains a constant gap between the tools. The electrodes are moved towards the workpiece, causing continuous discharge machining.

However, in the conventional electric discharge machining as described above, the discharge area has a close relationship with the peak current value I _p , which is the discharge processing condition most closely related to the discharge machining performance. The method of deciding how to determine is not presented, and especially in the case of 3D electric discharge machining, the electric discharge machining area cannot be predicted. In the case of discharging the remaining shapes after preliminary processing of the workpiece for shortening, it is more difficult to calculate the discharge machining area, which makes it more difficult to determine the discharge machining conditions.In addition, the discharge machining method is a machining method using discharge heat. It is very difficult to estimate the machining time, so the discharge machining time As a method of estimating has not been suggested, it is impossible to establish a production plan, and based on the experience of a skilled worker, the optimal discharge machining condition is calculated or the discharge machining time is estimated. It is urgent to calculate the conditions and the discharge machining time.

The present invention was created in order to solve the problems caused in the conventional electric discharge machining as described above, in the case of the discharge discharge and the pre-discharge machining the direct discharge processing without pre-processing the workpiece in the three-dimensional discharge machining The purpose of the present invention is to provide a method for determining the optimum discharge machining conditions and to make it possible to easily estimate the discharge machining time. will be.

Therefore, in order to achieve the above object, in the three-dimensional discharge machining, since the discharge machining areas according to the machining parts are different from each other, the method of first obtaining the free machining area from the tool electrode curved surface and from the NC code for machining the tool electrode are performed. Z-Map modeling to find out the discharge machining area and the tool electrode measuring the discharge machining area from the data measured by a three-dimensional measuring instrument.

1 is a schematic view showing the structure of an electric discharge machine.

2 is a schematic diagram showing a grid search method applied to the present invention.

3 is a curved curve generated with the curved surface and the plane according to the present invention.

4 is a graph showing the calculation of the discharge area from the cross curve.

5 is a plan sectional view showing the discharge machining area;

FIG. 6 is a graph illustrating determination of the discharge area region of FIG. 5; FIG.

7 is a graph showing determination of a contact point.

8 is a graph showing a Z-map.

9 is a graph showing a path of a ball end mill.

10 is a graph showing initialization of a Z-map.

11 is a graph showing the maximum and minimum of the tool moving point.

12 is a state diagram showing a Z-map modeled from an NC code.

FIG. 13 is a graph for calculating a discharge area in a Z-map. FIG.

14 is a state diagram showing data measured by a three-dimensional measuring instrument.

15 is a graph for forming a three-dimensional measurement point in a triangular network.

16 is a state diagram showing an example in which a measuring point is formed of a triangular net;

17 is a graph showing Z values for grid points in a polyhedron.

18 is a state map modeled from a polyhedron (Z-map).

19 is a conceptual view of the discharge machining of a pre-processed object.

20 is a state diagram showing a Z-map modeling result of a pre-processed object.

FIG. 21 is a graph illustrating a Z-map modeling process of tool electrodes. FIG.

22 is a schematic diagram for calculating a volume of electric discharge machining.

Hereinafter, the method of calculating the optimum discharge processing conditions and the method of estimating the discharge processing time in the three-dimensional discharge processing by the method proposed in the present invention will be described.

First, the method of calculating the discharge processing conditions in the three-dimensional discharge processing is as follows.

When calculating the conditions of discharge machining in 3D discharge processing, the first requirement is to find the intersection of the shape to be processed according to the same height. Thus, in the surface modeling, the method of finding the intersection between two surfaces is algebraic method, grid search method, There are tracing method and subdivision method. Among them, the grid search method is proposed as a suitable method for finding the intersection between the horizontal plane and the free curved surface having a constant height, and the free surface and horizontal plane by the grid search method. Model the Z-map from the NC code to obtain the discharge area from the intersection or to process the tool electrodes, and then calculate the spinning surface from the Z-map or use the 3D measuring machine (CMM). The tool geometry is approximated by the triangular polyhedron from the data obtained through the data. Z-map modeling is performed by dividing the XY plane section of triangular polyhedron by lattice spacing using the plane equation representing triangular polyhedron and calculating the corresponding Z values. map) When modeling is done, calculate the depth of discharge.

In addition, when the electric discharge machining area for the electric discharge machining position is calculated by the above method, the optimum electric discharge machining condition should be determined. In order to determine the optimum electric discharge machining condition, a current density suitable for the material of the electrode and the workpiece is determined. It is to determine the discharge machining condition so that it can be kept constant.

In this case, since the discharge machining process is slow, in order to shorten the processing time and improve productivity, after the preliminary processing of the workpiece by the method such as cutting process, the remaining parts are generally processed by the discharge machining. To geo-map the geometry of the workpiece and to process the tool electrodes from the NC code for pre-machining the workpiece to determine the optimum discharge machining conditions in an efficient and systematic way in the case of the discharge machining of the pre-processed object. After geo-modeling the geometry of the tool electrode from the NC code or the curve modeling the geometry of the tool electrode, we determine the discharge processing conditions appropriate for the discharge area based on the two modeled G-maps. Tool from surface modeling NC code or tool electrode for preliminary processing If the discharge area is calculated by geo-map modeling the geometry of the electrode, the discharge machining conditions can be determined in the same way as the three-dimensional discharge machining conditions.

Therefore, the method for calculating the optimum discharge machining conditions for the workpiece by the above methods is as follows.

Example 1

In Example 1, the tool electrode is modeled as a curved surface, and then the area is calculated by a grid search method, which is a method of obtaining an intersection between two curved surfaces.

As a method of finding the intersection between the free surface r (u, v) = x (u, v), y (u, v), z (u, v) and the horizontal surface z = h, the parameter of the surface r (u, v) When (u _i , v _j ) is a grid point after forming a square grid in the (parameter) region, any grid cell has four grid points (u _i , v _j ), (u as shown in FIG. _{i + 1} , v _j ), (u _i , v _{j + 1} ), (u _{i + 1} , v _{j + 1} ), and after examining whether the intersection of the horizontal and curved surfaces passes through the grid cell, If the intersection crosses the corner of two points (u _i , v _j ) and (u _{i + 1} , v _{j + 1} ) at both ends, the following equation is satisfied.

[Equation 1]

The intersection point on the edge by Equation 1 is easily obtained by the numerical method. When the intersection line passes through the grid cell, the intersection point with the edge exists so that another intersection point is found in a similar manner.

In this way, the entry intersection point and the retreat intersection point exist in one grid cell, and the obtained retreat intersection point becomes the entry intersection point of the neighboring grid cell, so that intersection points for neighboring grid cells can be obtained continuously and the first starting point is reached or the boundary of the free curve Continue until you reach one, and after finding one bridge, find the bridge in the same way for the remaining grid cells.

Therefore, by using the method described above, the intersection between the curved surface of the tool electrode and the XY plane corresponding to the discharge machining depth is obtained, and the discharge machining area is obtained from the intersection, the intersection generated by the tool electrode curved surface and the plane corresponding to the discharge machining position. As shown in FIG. 3, a closed curve is formed, and the discharge processing area can be obtained by obtaining an area inside the bridge that forms such a closed curve, and the bridges forming the closed curve are connected to a plurality of intersections, and thus a closed polygon made of bridges. As shown in FIG. 4, the area of the closed polygon is a position vector of a line segment constituting one side of the polygon in the triangle OAB. , In other words, the vector area of triangle △ OAB is The area of the entire polygon is given by Eq.

[Equation 2]

In addition, in the case where there are a plurality of intersections between the electrode curved surface and the plane of the discharge position, the sum of the areas of the closed curves formed by the intersection curves calculates the discharge area at the discharge machining position, as shown in FIG. 5. Similarly, since the inside of the closed curve surrounded by the intersection CV ₂ inside the discharge machining surface is a concave area unless it is processed, the actual discharge area is the area S ₁ surrounded by the intersection CV ₁ except the area S ₂ of the concave area. In order to calculate the accurate discharge machining area, it is necessary to distinguish the bridges corresponding to the concave areas where the discharge is not performed from the entire bridges, and to determine the bridges corresponding to the concave areas where the discharge is not processed. As shown in After finding the intersection point of the straight line (decision line) set in one direction and the other intersections (decision point) at one point on the intersection line indicated by ', the decision points between the decision line and the intersection points are shown as' ×. If the number of intersections is even, the area surrounded by the corresponding intersection is discharged area, and if it is odd, the area surrounded by the intersection is determined as a concave area where discharge is not generated. For convenience, the contact is generated at the vertices of the intersection polygon when the judgment line is in contact with the closed polygon consisting of intersections.

Therefore, if three consecutive vertices of the cross polygon are P ₁ , P ₂ , and P ₃ as shown in FIG. 7, the center point P ₂ passes through P ₂ when the center point P ₂ is the judgment intersection. When the direction vector is 'u', the decision intersection becomes a contact point as shown in FIG. 7 when the condition of Equation 3 is satisfied.

[Equation 3]

or,

here,

Example 2

When the calculation of the discharge area is completed as in Example 1, the curved surface Z value must be obtained at grid points (i, j) at regular intervals defined in the X and Y planes. The Z-map can be obtained by using the Z-map. The Z-map has only a height value at each lattice point to simulate and verify the 3-axis NC machining procedure on a computer. As shown in FIG. 8, at each lattice point, one side of the lattice point is a solid rectangular column whose height is the size of the grid spacing and whose height corresponds to the height z at the lattice point. By extending the concept of Z-map, it is possible to easily calculate the discharge machining area for the discharge machining position.The track surface formed when the ball end mill moves to process the tool electrode moves the sphere. Since it is a formed surface, it becomes a cylinder surface, and a ball end Grid on the height value z _p a will schematic diagram is as shown in Figure 9 and finding, w (plan view from the sectional view represented in Fig. 9 w are obtained in advance in the plan view of a grid point (x _p, y _p) in the trajectory plane of The vertical distance between the point and the tool center line) is obtained. By applying a simple trigonometric function in the cross section, the height value z _p can be obtained from the side view.

[Equation 4]

Example 3

In order to calculate the discharge area with respect to the discharge depth, Z-map modeling of the geometry of the tool electrode from the NC code is performed. This modeling procedure is as follows.

Step 1: From the NC code for machining the tool electrodes, the maximum (Max.x, Max.Y, Max.z) and minimum (Min.x, Min.y, Min.x) points for the tool's movement path Obtain

Step 2: Divide the section on the XY plane formed by the maximum point and the minimum point calculated in step 1 by a certain lattice spacing (g), and calculate the number of gratings in the X direction (gxNo) and the number of gratings in the Y direction (gyNo) as shown in FIG. After retrieval, we initialize each z _p value at each lattice point (X _p , Y _p ) to the maximum point (Max.z) calculated in step 1.

Step 3: Attached drawings As shown in Fig. 11, the tool moving point P _i-1 , P _i is the center point of the cylinder from the NC code, and the radius of the cylinder corresponds to the range of the cylinder surface equal to the radius of the ball end mill used for the tool electrode. To determine the minimum and maximum.

Step 4: At each grid point of the grid area determined in step 3, obtain the height W shown in FIG. 9, and the grid point smaller than the tool radius R is obtained by obtaining the height Z _p of the grid point. Update the z value of to the calculated Z _p .

Step 5: Repeat steps 3 and 4 above.

The geometric shape of the tool electrode can be obtained as shown in FIG. 12 from the NC code obtained through the modeling procedure as described above.

Example 4

Therefore, when the modeling by the Z-map is completed according to the third embodiment, the discharge area at an arbitrary discharge machining position C _z is Z-map as shown in FIG. 13. Calculate the number of grids whose height Z at each lattice point is larger than the discharge machining position C _z from the model and multiply the area of the square whose length (g) is the one side as shown in Equation 5.

[Equation 5]

Where g: the size of the grid grid.

C _z : Random discharge machining position.

N; The number of grids in which the height Z [i] [j] of the grid points is larger than the discharge machining position C _z .

In addition, if there is no geometric information about the tool electrode or NC code for machining the electrode, and only the actual object of the tool electrode, the tool electrode is measured by a three-dimensional measuring device (CMM) and approximated to a triangular polyhedron based on the measured point data. After calculating the discharge area from the Z-map model of the approximate polyhedron, the optimal discharge condition can be determined based on the calculated discharge area. It is.

Example 5

As shown in FIG. 14, if there is point data measured by a 3D measuring device in real, the four points consisting of the closest points are determined from the measured two points of data to form a triangular network. As shown in FIG. 16, a triangle including a short diagonal line is selected by comparing the diagonal lengths d1 and d2 of the OAB and the OAC that can form a triangle from the measured points. As shown in FIG. 1, it is possible to obtain a measurement point formed of a triangular net.

Example 6

Since the Z-map expresses the Z value of the curved surface only at regular intervals of grid points (i, j) defined in the XY plane, the shape of the tool electrode approximated by a triangular polyhedron is shown in FIG. 17. Z-map modeling is possible by dividing the XY plane section of the triangular polyhedron by the lattice spacing and calculating the Z value corresponding to each lattice point using the plane equation representing the triangular polyhedron. This is the result of Z-map modeling the geometric shape of tool electrode approximated by triangular polyhedron.

When the Z-map is modeled on the basis of the data measured with the real tool electrode using the 3D measuring device as described above, the discharge area is obtained from the Z-map by the method of Example 4 The discharge area for the discharge depth can be obtained.

Therefore, when the discharge area obtained from the above embodiments is obtained, the discharge machining conditions must be determined. In order to determine the optimum discharge machining conditions, the discharge machining conditions are maintained so that the current density suitable for the material of the electrode and the workpiece can be kept constant. Determination of the discharge processing conditions can be obtained by the seventh embodiment.

Example 7

The current density is the average processing current per unit area, which is determined by the peak current (I _p ) and the pulse on time (τ _p ) .Equation 6 shows the current density for single discharge. In order to process adaptively according to the change of, the electric discharge machining condition should be determined so that the average processing current density (Jm) of Equation 6 is constant.

[Equation 6]

Where τ _p : pulse on time (μs)

τ _r : rest time (μs)

τ _w : delay time (μs)

S: discharge processing area (cm ² )

I _p : peak current (A)

D: Duty factor

In this case, the impact coefficient D can be expressed as shown in Equation 7 below, and the delay time τ _W in the impact coefficient is a very small value compared to the pulse on time τ _p and the rest time τ _r . Therefore, the impact coefficient (D) shown in Equation 7 can be simplified as shown in Equation 8.

[Equation 7]

[Equation 8]

In the present invention, in order to improve the productivity of the discharge machining in one of the three methods presented above to determine the discharge machining conditions that can maximize the discharge machining speed in the range of no damage to the electrode When the discharge processing area is determined, the peak current value I _p that satisfies Equation 6 can be obtained by Equation 9 so that the average current density can be kept constant.

[Equation 9]

At this time, the discharge area and the optimal current density are not known, but the impact coefficient (D) is unknown, so the equation cannot be solved. Therefore, if the impact coefficient (D) is fixed at a constant value in Equation 9, the peak current value (I _p) appropriate for the discharge area is obtained. If the peak current value (I _p ) is determined, the pulse on time (τ _p ) and the pause time (τ _r ) should be determined.The peak current value (I _p ) and the pulse on time (τ _p ) according to the so electrode somobi (ε) is determined as shown in equation 10 will, which is available for the electrode somobi pulse on-time (τ _p), such as when formula 11 fixed to the appropriate value, the impact when the determined pulse-on time (τ _p) Since the coefficient D is fixed, the idle time τ _r required for insulation recovery can be determined from the impact coefficient D of Equation 8 as shown in Equation 12.

[Equation 10]

[Equation 11]

[Equation 12]

As another condition of the present invention, the electric discharge machining takes much more processing time than the general cutting method, so as to reduce the processing time and improve productivity, as shown in FIG. After discharging the remaining parts, it is generally carried out. In order to determine the optimum discharge machining conditions in an efficient and systematic manner for discharging the object subjected to the preliminary processing, Z-map modeling of the geometry of the workpiece from the NC code, and Z-map modeling of the geometry of the tool electrode from a curve modeling the geometry of the NC electrode or tool electrode for machining the tool electrode. After modeling, based on the two modeled Z-maps, The method of determining the pre-processing conditions can be carried out by the following example, and the discharge area for the discharge machining position is calculated from the modeled two Z-maps and the same discharge as the three-dimensional discharge machining. The processing conditions can be determined.

Example 8

In the three-dimensional discharge, which directly discharge-processes raw raw materials, the discharge area can be calculated only by the shape information of the tool electrode. However, the pre-processed workpieces have different heights in the machining area. The geometric shape information of the tool electrode is required, and Z-map modeling of the preprocessed workpiece and Z-map modeling of the tool electrode are performed to determine the machining conditions for the discharge area. Should

First, in order to model the Z-map of the pre-processed workpiece, Z-map modeling of the shape of the workpiece from the NC code for pre-processing the workpiece is performed. It can be obtained through the same procedure, the accompanying drawings Figure 20 shows the Z-map modeling obtained from the NC code.

In addition, the Z-map modeling representing the geometry of the tool electrode can be generated from a curved surface modeling the tool electrode or an NC code for processing the tool electrode. The Z-map modeling procedure from the code is the same as the Z-map modeling of the shape of the workpiece, but in the discharge machining, the tool electrodes are mounted upside down on the ram and move downwards. Z-map modeling of the shape of the tool electrode as shown in FIG. 21 and processing the Z value of each lattice point with respect to the base line, then Z at the lattice point. The value moved in the + Z direction by the height of the tool electrode is a Z-map representing the shape of the tool electrode.

The process of determining suitable discharge machining conditions in the discharge machining of the pre-processed workpiece is as follows.

Step 1: Z-map model the shape of the workpiece from the NC code for pre-machining the workpiece.

Step 2: Z-map modeling of the shape of tool electrode from NC code for tool electrode or curved surface modeling tool electrode.

Step 3: Move the tool electrode downward by a certain height (dz) and store the tool electrode Z-map as small as the height (dz) of each grid point.

Step 4: Calculate the discharge area S = N ^* g ² by determining the number of lattice N whose height of each lattice point of the preliminary workpiece WZ is larger than the height of each lattice point of the tool electrode TZ.

Step 5: Determine the discharge processing condition based on the calculated discharge area.

Step 6: The preliminary workpiece WZ larger than the height of the tool electrode TZ with respect to the entire lattice point is updated to the height of the tool electrode.

Step 7: Repeat the steps 3 to 6 for the entire discharge section.

When the conditions for electric discharge machining are calculated according to Examples 1 to 8, the production time can be increased by estimating the machining time based on this, and the productivity of the tool electrode can be estimated in order to estimate the systematic machining time. The method of estimating the discharge machining time using a curved surface modeling the shape, and the Z-map modeling of the geometry of the tool electrode from the NC code for machining the tool electrode. The discharge machining time is determined by the discharge machining speed (discharge machining weight), and the discharge machining speed is different depending on the material of the tool electrode, the material of the workpiece, and the applied discharge machining conditions. In the method of estimating time, the present invention has the greatest influence on the discharge machining among the plurality of discharge machining conditions. Factor of the peak current (I _p), the pulse-on time (τ _p), pulse off-time method for estimating a processing time from the relationship between the discharge (τ _r) and electrical discharge machining by weight are as described in Example 9.

Example 9

The discharge machining speed W (g / min) is a function of the peak current (I _p ) and the impact coefficient (D) as shown in Equation 13, so that the discharge machining time can be easily estimated by knowing the discharge machining weight and the applied discharge machining conditions. .

[Equation 13]

Here, α and β are discharge rate coefficients, which depend on the material of the tool electrode and the material of the workpiece.

In addition, the estimation of the discharge machining time is different from the estimation of the discharge machining time required for discharge and discharge of the unprocessed object and the estimation of the time required for discharge machining the preprocessed object. As a method of calculating the discharge machining weight during discharge machining, the discharge machining weight can be calculated from a curved surface modeling the tool electrode, and the geometry of the tool electrode from the NC code for machining the tool electrode. Z-map) is a method of calculating the discharge processing weight by modeling, the method of calculating the discharge processing weight by calculating the discharge area from the curved surface of the tool electrode as shown in the former as shown in FIG. When the discharge area is calculated using Equation 2 from the cross-sectional shape information of the tool electrode, the discharge to be removed by the discharge machining at the discharge machining position Weight W is shown in Equation 14.

[Equation 14]

Here, S _i is the cross section of the tool electrode at an arbitrary discharge machining position, dz is the depth of the discharge machining section, and γ is the specific weight of the workpiece.

In addition, when the discharge area is calculated as shown in Equation 5 from the Z-map, the discharge processing weight can be calculated as shown in Equation 14.

As described above, when the discharge machining weight is calculated, the discharge machining time can be calculated. The relationship between the discharge machining condition and the discharge machining speed can be calculated from the information of the discharge machining conditions applied to the discharge machining and the calculated discharge machining weight. When the discharge machining weight is calculated, the discharge machining time T _EDM can be obtained from the theoretical experimental formula for the discharge machining rate coefficient and the discharge machining rate of Equation 13.

[Equation 15]

Here, W _(EDM) is the discharge processing weight, and I _p is the peak current which is the discharge processing condition.

Therefore, in order to estimate the machining time in three-dimensional discharge machining, first, the total discharge depth is divided into a plurality of sections at regular intervals, and when the geometric information of the tool electrode is given as a curved surface, the cutting plane corresponding to the electrode curved surface and the section depth for each section and After calculating the intersection of, calculate the area of the polygon consisting of the intersection with Equation 2, and if the geometric information of the tool electrode is NC code, calculate it using Equation 5 from the modeled Z-map and discharge area. Calculate the discharge processing weight by multiplying the discharge area by the area discharge depth and the specific weight of the workpiece, and then calculate the discharge processing time for each section from the relationship with the processing conditions applied to the discharge processing. The sum of the processing times for each star yields the total discharge processing time as shown in Eq.

[Equation 16]

As such, the present invention does not simply determine the processing conditions or estimate the processing time based on the expert's experience in electric discharge machining, but rather presents the exact basis of the calculation. By providing a method to determine the optimum discharge machining conditions for the discharge machining of the workpiece and to easily estimate the discharge machining time accordingly, the planned machining conditions and planned production is possible.

Claims (7)

A method for determining an optimum discharge machining condition for electric discharge machining, characterized in that after calculating an intersection between a tool electrode and a horizontal area during a three-dimensional electric discharge machining, calculating a discharge machining area by calculating a cross sectional area of the tool electrode from the intersection. The method of claim 1, A method for determining an optimum discharge machining condition in electric discharge machining, wherein the electric discharge machining area for the discharge position is determined by using a grid search method for the cross-sectional area of the tool electrode. The method of claim 1, Method for determining the optimum discharge processing conditions in the discharge machining, characterized in that for determining the discharge machining area for the discharge position using a Z-map cross-sectional area of the tool electrode. The method according to claim 1 or 3, If there is no curve for the tool electrode and there is an NC code for machining the tool electrode, Z-map modeling of the shape of the tool electrode from the NC code is used to determine the discharge machining area for the discharge position. Method for determining the optimum discharge processing conditions in the electrical discharge machining. The method according to claim 1 or 3, If there is no curved surface for the tool electrode and the NC code for processing it, the shape of the tool electrode is approximated to a triangular polyhedron from the data of the actual measurement of the tool electrode with a three-dimensional measuring instrument, and the approximate triangular polyhedron A method for determining an optimum discharge machining condition in electric discharge machining, characterized in that the electric discharge machining area for the discharge position is determined based on the modeling. The method according to claim 1 or 3, When discharging a pre-processed object, the shape of the tool electrode and the workpiece is Z-map modeled to determine the discharge machining area for the discharge position based on this. How to determine the condition. A method for estimating the discharge machining time in the discharge machining, characterized by calculating the discharge machining time from the relationship between the discharge machining condition and the discharge machining speed from the discharge machining conditions applied to the discharge machining and the calculated discharge machining weight information.