JP2000084741A - Electric discharge machining device and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress irregularities of machining quantities on a machining bottom face, by obtaining an average machining width relative to each machining path or each contour path from an actual machining region, and by acquiring an optimum electrode wear correction coefficient from the average machining width. SOLUTION: An actual machining region 82 overlapping a machining region 212 of obtained machining path 112 and a machining remaining region 72 is calculated. An average machining width is calculated by dividing the actual machining region 82 by a machining path length. The machining path length is calculated from a machining path memorized in a machining path memory part. An optimum electrode wear correction coefficient is calculated from the average machining width by an optimum electrode wear correction coefficient calculation part. An electrode wear correction coefficient change code is outputted with one machining path unit. The electrode wear correction coefficient memorized in an electrode wear correction coefficient memory part is changed into the obtained electrode wear correction coefficient by the electrode wear correction coefficient change code.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric discharge machining apparatus and an electric discharge machining method, and more particularly, to an electric discharge machining apparatus and an electric discharge machining method which are less likely to generate a step or undulation on a machining bottom surface of a work and can shorten machining time.

[0002]

2. Description of the Related Art Conventionally, a tool electrode having a simple shape such as a cylinder, a cylinder, a prism, etc. is three-dimensionally moved by numerical control instead of a transfer processing using a forming tool, and a workpiece is formed into a desired three-dimensional shape. 2. Description of the Related Art An electric discharge machining apparatus for machining is known. In such an electric discharge machining apparatus, there is no need to produce a complex shaped tool electrode having a complicated shape, and therefore, there is an advantage that the mold production cost and the production time can be improved. Further, since a tool electrode having a simple shape is used, there is an advantage that standardization of the tool electrode is possible, construction of a CAM system is easy, and automation of a machining process can be expected.

However, in such an electric discharge machine,
Since a wide area is machined using a tool electrode having a simple shape, accuracy of the machined shape becomes a problem compared to electric discharge machining using a full-shaped electrode.

FIG. 11 is an explanatory view showing a conventional electric discharge machining method. A cylindrical tool electrode 501 with respect to the workpiece W
Is lowered from the position A to the position B, a discharge removal phenomenon occurs between the workpiece W and the tool electrode 501. The workpiece W is moved to the tool electrode 501 by the removal action by the intermittent discharge.
Process into the shape of Subsequently, the tool electrode 501 moves horizontally from the position B to the position C according to the machining path (the machining amount 502). Thus, the removal processing of the predetermined shape is performed by the tool electrode 501 having the simple shape. Further, since the tool electrode 501 is consumed by the discharge phenomenon, the tool electrode 501 is vertically moved downward in the machining process to correct the consumption of the tool electrode 501 (electrode consumption amount 503). Therefore, the tool electrode 501
Means that in the processing step, a movement combining the horizontal movement and the vertical movement is performed (the oblique feed amount 50).
4).

As a technique for correcting such a tool electrode, an EDM apparatus described in Japanese Patent Application Laid-Open No. 5-345228 is known. FIG. 12 is an explanatory diagram of a method of correcting a tool electrode in the EDM device. In this electric discharge machining,
Machining is performed while rotating the cylindrical tool electrode 601 at a predetermined angle (electrode oblique feed angle) α with respect to the electric discharge machining surface of the work W. Thereby, the tool electrode 601 is formed.
It is possible to create a steady state after the position (d) where the contour shape and machining depth of the tool electrode 601 do not change through the transitional state from the position (a) to the position (d) where the contour shape and the machining depth change. it can.

The electrode oblique feed angle α is determined in consideration of the machining amount in a steady state and the amount of electrode consumption. Assuming that the thickness E is one layer, the radius R of the machining electrode, the cross-sectional area S of the machining electrode, and the volume consumption rate U, the electrode oblique feed angle α of the cylindrical tool electrode 601 is tan (α) = R · E · It can be determined by U / S.

The electrode oblique feed angle α of the cylindrical tool electrode 601 is determined by the outer radius R of the tool electrode 601.
1, assuming that the inner radius is R2, tan (α) = (R1 + R2) .EU / S = EU / π (R1-R2).

In this EDM apparatus, the above-mentioned calculation formula for the wear correction is prepared according to the shape of the tool electrode 601. Further, the EDM device includes a simulator that calculates a value for performing wear correction of the tool electrode 601. The simulator calculates the electrode oblique feed angle α from the thickness E of the first removal layer, the radius R of the tool electrode, and the wear volume U.
Based on the electrode oblique feed angle α, the numerical control unit of the EDM device gives a tilting motion to the tool electrode 601 to perform the wear correction of the tool electrode 601. With this configuration, the machining can be performed by using the tool electrode consumption area, so that the machining speed can be increased.

Next, the processing area by the tool electrode will be described. FIG. 13 is an explanatory diagram illustrating a horizontal movement trajectory of the tool electrode. First, the tool electrode 701 is shown in FIG.
As shown in FIG. 8, the initial machining remaining area 751 is moved along the machining path on the machining path 703 between AB and the machining path 7 between BC.
04 move on.

Here, a processing area to be removed from the work W will be considered. The machining area is a tool electrode 7 for machining.
01 means the part which passed. In FIG.
3, 724 is a processing area. Also, the processing area 723,
The machining width of 724 is a value obtained by adding the diameter of the tool electrode 701 and the discharge gap (both sides). When the tool electrode moves along the machining path 705 between CDs, the machining path 706 between DEs, and the machining path 707 between EFs and returns to the machining start point A as shown in FIG. The path 721 ends. Therefore, the actual machining width in the first contour path 721 is the sum of the diameter of the tool electrode 701 and the discharge gap (both sides).

Next, the tool electrode 701 is placed in the unprocessed area 7.
The machining path 708 between the FGs is moved to the 52 side. The pick feed amount of the tool electrode 701 is usually
1 radius. The tool electrode 701 moves along the machining path 709 between GH and the machining path 710 between HI, and continues the removal processing of the processing area. Therefore, the second contour path 73
The actual machining width in No. 2 is the sum of the radius of the tool electrode 701 and the discharge gap (one side) since the pick feed of the tool electrode 701 becomes the tool radius.

[0012]

However, in the above-mentioned conventional electric discharge machining, as shown in FIG. 13, the actual machining width differs for each of the contour paths 731 and 732 in the remaining machining area. Further, as the machining shape becomes more complicated, even within the same contour path 731, the machining paths 703 to
The actual processing width starts to vary every 707. For this reason, the processing amount of the work W becomes non-uniform, and there is a problem that a step or undulation is generated on the processing bottom surface of the work W. Also,
In order to remove steps and undulations on the processed bottom surface, a finishing process is required, and it is necessary to reduce the thickness of one layer and perform a plurality of removal processes on the processed bottom surface. For this reason, there is a problem that the processing time increases.

Accordingly, the present invention has been made in view of the above, and an object of the present invention is to provide an electric discharge machining apparatus and an electric discharge machining method in which a step or undulation is hardly generated on a machining bottom surface of a work and machining time can be shortened. I do.

[0014]

In order to achieve the above-mentioned object, an electric discharge machine according to the present invention applies a pulsed voltage between a tool electrode and a workpiece and simultaneously applies a pulse-like voltage in the longitudinal direction of the tool electrode. In an electric discharge machine that performs electric discharge machining while correcting wear based on an electrode consumption correction coefficient, a machining remaining area acquisition unit that acquires a machining unprocessed area every time machining is performed, and machining that acquires a machining area from a tool electrode and a machining path. An area acquiring unit, an actual machining area acquiring unit that acquires an actual machining area that is an actual overlapping area of the machining area and the remaining machining area, and the actual machining area is defined by a contour path length or a machining path length. Means for obtaining an average processing width by dividing to obtain an average processing width,
And an optimal electrode consumption correction coefficient acquiring means for acquiring an optimal electrode consumption correction coefficient based on the average processing width, and performing the consumption correction using the acquired electrode consumption correction coefficient.

Conventionally, since the processing width is different for each contour path, the processing amount is not uniform. However, according to the present invention, an actual processing area to be actually processed is obtained, and the actual processing area is determined for each processing pass. Alternatively, an average machining width is obtained for each contour pass, and an optimum electrode wear correction coefficient is obtained from the average machining width. Normally, the tool electrode is moved in the length direction by the Z-axis feed in the electric discharge machine, but the movement of the tool electrode is performed based on the optimum electrode wear correction coefficient, so that the variation in the machining amount on the machining bottom surface is effectively suppressed. it can. For example, when the average contour width is smaller in the second contour path than in the first contour path, the feed amount of the tool electrode in the Z-axis direction is reduced. With this configuration, it is possible to reduce the level difference and undulation on the processing bottom surface. Further, since the dependence on the finishing processing is reduced, the processing time can be reduced.

In the electric discharge machining apparatus according to the next invention, in the electric discharge machining apparatus described above, when electric discharge machining is performed by using the entire diameter of the tool electrode, a machining area is acquired for each contour pass, and the actual machining area is contoured. Acquire the electrode wear correction coefficient for the contour path from the average machining width divided by the path length, and when performing EDM using a part of the diameter of the tool electrode, acquire the machining area in machining path units and perform actual machining. The normal electrode consumption correction coefficient is obtained from the average processing width obtained by dividing the area by the processing path length.

As a result of experiments conducted by the inventors, when electric discharge machining is performed using the entire diameter of the tool electrode, the electrode wear correction coefficient is determined in contour path units rather than acquiring and correcting the electrode wear correction coefficient in machining path units. It has been found that a better machining state can be obtained by acquiring the above and correcting the wear. Therefore, when electric discharge machining is performed using the entire diameter of the tool electrode, an electrode wear correction coefficient is obtained in contour path units, and in other cases, an electrode wear correction coefficient is obtained in machining path units. With this configuration, it is possible to effectively suppress the occurrence of steps and undulations on the processing bottom surface.

The electric discharge machining apparatus according to the next invention is the electric discharge machining apparatus according to the above, further comprising, for the first contour path, obtaining a machining area for each contour path and dividing the actual machining area by the contour path length. An electrode wear correction coefficient for the first contour pass is acquired from the machining width, and the second contour pass or the first contour pass is corrected.
For the machining paths subsequent to the contour path, a machining area is acquired in machining path units, and a normal electrode wear correction coefficient is acquired from an average machining width obtained by dividing the actual machining area by the machining path length.

Regarding the first contour path, the inventors have found that, as a result of the experiment, the electrode wear correction coefficient is obtained for each contour path rather than the electrode wear correction coefficient obtained for each machining path, and the electrode wear correction coefficient is obtained. It has been found that a better processing state can be obtained by correcting. Therefore, regarding the first contour path,
The electrode wear correction coefficient is obtained for each contour path, and the electrode wear correction coefficient for each of the other second contour paths and machining passes is obtained. If you do this,
The generation of steps and undulations on the processing bottom surface can be effectively suppressed.

[0020] In the electric discharge machining apparatus according to the next invention, in the electric discharge machining apparatus, when the machining area acquiring means acquires the machining area, the electric discharge gap of the tool electrode is taken into consideration.

Usually, a discharge gap is formed around the tool electrode. For this reason, when actually machining, it is machined by the width obtained by adding the discharge gap to the diameter of the tool electrode. In the present invention, a machining region is obtained in consideration of the discharge gap. For this reason, as a result of being able to obtain the machining region accurately, it is possible to obtain the electrode wear correction coefficient more optimally.

The electric discharge machining apparatus according to the next invention is the electric discharge machining apparatus described above, wherein the average machining width obtaining means sets the actual machining area as a rectangle, divides it by a machining path length or a contour path length, and The processing width is obtained.

When the outer shape of the tool electrode is circular and a plurality of tool electrodes having different diameters are used, the actual machining area is not necessarily rectangular. Therefore, since the machining path length can be calculated, the actual machining area is regarded as a rectangle, and then divided by the machining path length or the contour path length to obtain an average machining width.

In the electric discharge machining method according to the next invention, a pulse-like voltage is applied between the tool electrode and the workpiece, and the electric discharge machining is performed while correcting the wear in the length direction of the tool electrode based on the electrode wear correction coefficient. In the electric discharge machining method, a machining remaining area acquisition step of acquiring a machining remaining area each time machining is performed,
A machining area acquisition step of acquiring a machining area from a tool electrode and a machining path, and an actual machining area acquisition step of acquiring an actual machining area to be actually machined, which is an overlapping area of the machining area and the remaining machining area, An average machining width acquisition step of acquiring the average machining width by dividing the actual machining area by the contour path length or the machining path length, and an optimal electrode consumption compensation coefficient acquiring step of acquiring an optimal electrode consumption compensation coefficient based on the average machining width. And the consumption correction is performed using the acquired electrode consumption correction coefficient.

First, an actual machining area to be actually machined is determined. The actual machining area is an overlapping area of the machining area and the remaining machining area. Next, an average machining width is determined for each machining pass or contour path from the actual machining area. The average processing width is obtained by dividing the actual processing area by the processing path or the contour path. Then, an optimum electrode wear correction coefficient is obtained from the average processing width, and electric discharge machining is performed using the electrode wear correction coefficient. Conventionally, the processing width was varied due to different processing widths. In this way, if the electrode consumption correction coefficient is obtained for each processing path or contour path having a different processing width, the processing amount can be varied. Can be effectively suppressed. For this reason, steps and undulations on the processing bottom surface can be reduced. Further, since the dependence on the finishing processing is reduced, the processing time can be reduced.

In the electric discharge machining method according to the present invention, in the electric discharge machining method, when electric discharge machining is performed using the entire diameter of the tool electrode, a contour path machining area acquiring step of acquiring a machining area in contour path units; An electrode wear correction coefficient for a contour pass for obtaining an electrode wear correction coefficient for a contour path from an average machining width obtained by dividing the actual machining area by a contour path length, and discharging using a part of the diameter of the tool electrode. In the case of machining, a machining path machining area acquisition step of acquiring a machining area in machining path units, and a normal electrode wear correction coefficient obtained from an average machining width obtained by dividing an actual machining area by a machining path length. And obtaining an electrode wear correction coefficient.

In the case of electric discharge machining using the entire diameter of the tool electrode, a machining area is obtained for each contour path, an actual machining area is obtained from the machining area, and the actual machining area is divided by the contour path to obtain an electrode wear correction coefficient. I got to get. on the other hand,
When electric discharge machining is performed using a part of the diameter of the tool electrode, an electrode wear correction coefficient is obtained for each machining pass. That is, only when performing EDM using the entire diameter of the tool electrode,
The electrode wear correction coefficient is obtained not in the unit of the processing pass but in the unit of the contour path. This is because
The inventors have conducted an experiment and found that when performing EDM using the entire diameter of the tool electrode, an electrode wear correction coefficient is obtained for each contour path, rather than obtaining an electrode wear correction coefficient for each machining pass. This is because it has been found that a better machining state can be obtained by performing wear compensation. Therefore, by performing the electric discharge machining in the above process, it is possible to effectively suppress the occurrence of steps and undulations on the machining bottom surface.

The electric discharge machining method according to the next invention is the electric discharge machining method according to the above, further comprising, for the first contour path, a contour path machining area acquiring step of acquiring a machining area for each contour path; A first contour pass electrode wear correction coefficient acquiring step of acquiring a first contour pass electrode wear correction coefficient from the average machining width divided by the contour path length. For subsequent machining paths, a machining path machining area acquisition step of acquiring a machining area in machining path units and a normal electrode wear correction coefficient are acquired from an average machining width obtained by dividing the actual machining area by the machining path length. A normal electrode wear correction coefficient acquiring step.

In the first contour pass, a machining area is acquired in contour path units, an actual machining area is obtained from the machining area, and the electrode machining correction coefficient is acquired by dividing the actual machining area by the contour path. . On the other hand, for the second contour pass and the machining pass, the electrode wear correction coefficient is obtained for each machining pass. That is, in the first contour pass, the electrode wear correction coefficient is calculated not in the machining pass but in the contour pass. The reason for this is that, based on experiments performed by the inventors, regarding the first contour path, rather than acquiring an electrode wear correction coefficient for each machining pass and performing wear correction,
This is because it has been found that a better machining state can be obtained by acquiring the electrode wear correction coefficient for each contour path and performing the wear correction. Therefore, by performing the electric discharge machining in the above process, it is possible to effectively suppress the occurrence of steps and undulations on the machining bottom surface.

[0030] In the electric discharge machining method according to the next invention, in the electric discharge machining method described above, further, in the machining area acquiring step, a discharge gap of a tool electrode is taken into consideration when acquiring a machining area.

When the discharge gap is taken into consideration, the actual machining state is approximated, so that the machining area can be accurately obtained. For this reason, the electrode wear correction coefficient can be obtained more optimally.

In the electric discharge machining method according to the present invention, in the electric discharge machining method, further, in the step of obtaining the average machining width, the actual machining area is regarded as a rectangle, and is divided by a machining path length or a contour path length. The processing width is obtained.

The outer shape of the tool electrode is circular. Also, machining is frequently performed using a plurality of tool electrodes having different diameters. For this reason, the actual machining area is not necessarily rectangular. Therefore,
In the present invention, the actual machining area is regarded as a rectangle, and then divided by the machining path length or the contour path length to obtain the average machining width.

[0034]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an electric discharge machining apparatus and an electric discharge machining method according to the present invention will be described in detail with reference to the drawings. The present invention is not limited by the embodiment.

Embodiment 1 FIG. 1 is a block diagram showing an electric discharge machine according to a first embodiment of the present invention.
This electric discharge machine 100 has a hollow cylindrical tool electrode 1.
An electrode rotating device 2 for rotating the tool electrode 1 about the axis of the tool electrode 1; a work table 3 on which the work W is placed; and a work liquid 4 provided on the work table 3 and storing a machining fluid 4 in a tank. And a processing tank 5 for sinking the work W. The tool electrode 1 and the work W are connected to a processing power source 6 for applying a voltage between them. The processing power supply 6 is controlled by the control device 7.

Further, the control device 7 has a storage unit 8 and a calculation unit 9. The storage unit 8 includes a processing path storage unit 801 that stores a processing shape path, a wear correction coefficient storage unit 802 that stores a wear correction coefficient of the tool electrode 1, and an electrical condition storage unit 803 that stores electrical conditions. ing. The calculation unit 9 includes a remaining processing area calculation unit 901 that calculates a remaining processing area that changes with the progress of processing, a processing area calculation unit 902 that calculates a processing area (area) using a processing path, and an average processing of the processing path. An average machining width calculator 903 for calculating the width,
An optimum wear correction coefficient calculator 904 calculates an optimum electrode wear correction coefficient based on the obtained average processing width. The control device 7 controls the X-axis drive device 10, the Y-axis drive device 11, and the Z-axis drive device 12 based on the machining shape path, the wear correction coefficient, and the electrical conditions, and controls the relative position between the tool electrode 1 and the workpiece W. Perform positioning.

Next, the optimum calculation of the electrode wear correction coefficient when the simple pipe electrode (1) is used in the electric discharge machine 100 will be described. FIG. 2 is a flowchart showing an electric discharge machining process by the electric discharge machine of FIG.
FIG. 3 and FIG. 4 are explanatory diagrams showing processing regions in the steps in the flowchart shown in FIG. The electric discharge machining method by the electric discharge machining apparatus 100 will be outlined. First, since the machining width differs for each machining pass, an optimum electrode wear correction coefficient is calculated based on the machining width for each machining pass. Next, the electric discharge machining is performed while the consumption of the tool electrode 1 is corrected using the electrode consumption correction coefficient. In the first contour pass, an optimum electrode wear correction coefficient is calculated not from each machining pass but from an average machining width using the contour path as a unit. After the second contour pass, the optimum electrode wear correction coefficient is calculated not from the contour pass unit but from the average machining width for each machining pass. Hereinafter, the details will be described along the flowchart.

In step S201, the unprocessed area of the solid work W is stored. The remaining machining area is calculated from the machining path stored in the machining path storage unit 801. The unprocessed area is substantially synonymous with the unprocessed area on the workpiece W.

In step S202, it is determined whether or not all machining passes have been completed. When all the machining passes are completed, the machining is completed. If not completed, the process proceeds to step S203, where electric discharge machining is performed according to the machining path stored in the machining path storage unit 801.

In step S203, it is determined whether the machining path is the first contour path. The contour path is a set of closed machining paths that make a round along the contour shape of the unprocessed area, as shown in FIG. 12 of the conventional example. In the case of the first contour pass, the process proceeds to step S204, and processing is performed under the conditions dedicated to the first contour pass. That is, the electrode wear correction coefficient is calculated not from each machining pass but from the average machining width of the first contour pass. The reason for selecting the processing conditions based on whether or not the first contour pass is based on the fact that the inventors have conducted an experiment and found that the first contour pass is not an average machining width for each machining pass but a contour. This is because it has been found that the machining state is better when the electrode machining coefficient is calculated from the average machining width of the pass and the electric discharge machining is performed.

First, the processing in the first contour pass will be described. In step S204, a machining area based on the contour path is calculated. Specifically, as shown in FIG. 3, the machining path 10 from the machining start point A to the intermediate point B on the workpiece W
1, processing path 102 between BC, processing path 10 between CD
3. Calculate the processing areas 201 to 205 of the contour path in which the processing path 104 between the DE and the processing path 105 from the intermediate point E to the processing start point A are collected. The processing area 61 of the first contour path 51 is obtained by adding the processing areas 201 to 205 of the processing paths 101 to 105 and excluding the overlapping portions 106 to 110 of the processing areas of the processing paths 101 to 105. .

In step S205, the processing area 61 and the remaining processing area 71 of the obtained first contour path 51 (step S205).
201) is calculated. in this case,
Since the work W is in a solid state, the first contour path 51
The overlap region 81 (for convenience, referred to as “actual machining region”) of the machining region 61 and the remaining machining region 71 coincides with the machining region 61 of the first contour path 51. In this case, the work W is processed using the entire diameter of the tool electrode 1.

In step S206, the unprocessed area 72 is calculated (see FIG. 4). The unprocessed region 72 is necessary for obtaining the actual processed region 81, and needs to be recalculated constantly because it changes each time the process is performed. The recalculation step S206 of the unprocessed area 72 does not have to be at this position, and may be performed at least immediately before step S205 of calculating the actual processed area 81.

In step S207, the average processing width is calculated by the average processing width calculation unit 903. The average processing width is
As shown in FIG. 5, it can be obtained by dividing the actual processing area (the processing area 61 of the contour path 51) 81 by the processing path length. The processing path length is calculated from the processing path stored in the processing path storage unit 801.

In step S208, the optimum electrode consumption correction coefficient calculating section 904 calculates an optimum electrode consumption correction coefficient from the average processing width. The wear correction coefficient is obtained by a basic experiment from the average processing width and set as processing conditions.

FIG. 6 is an explanatory diagram showing the relationship between the average processing width and the electrode correction coefficient. As shown in the figure, a case where a solid work W is machined by a straight machining path P will be described as an example. Since the tool electrode 1 has a circular cross section, when the tool electrode 1 moves from time Ta to time Tb,
One end of the processing region SE has a convex semicircular shape, and the other end has a concave semicircular shape (see FIG. 3A). Therefore, the processing area SE
Can be transformed into a rectangle.

The actual machining amount (machining volume) by the tool electrode 1 is equal to the machining width W × the machining length L × the machining thickness t of one layer (see FIG. 9B). In actual processing, since the processing is performed so that the processing conditions are constant, the processing amount is also constant, and further, since the processing length is constant, the processing width W
X The processing length L becomes constant. Here, the processing thickness t of one layer
Has a proportional relationship with the consumption correction coefficient k, so that a relationship of t = α × k (α is a constant coefficient) is established between the two.

Thus, if the processing length L is constant, the value of the processing width W × α × consumption correction coefficient k is constant. Therefore, it can be seen from the relational expression that the processing width W and the consumption correction coefficient k have an inversely proportional relationship. For example, if the processing width W is doubled, the consumption correction coefficient k may be reduced to 1/2.

Next, since the optimum electrode wear correction coefficient has been obtained, the electric discharge machining of the first contour path 51 is performed based on this. In step S209, it is determined whether the processing of the first contour path 51 has been completed. When the processing of the first contour path 51 is completed, the process returns to step S202. If the processing has not been completed, the process proceeds to step S210, and it is determined whether or not the machining path is the first path of the first contour path 51. If it is not the first pass, it means that the first contour pass 51 has not been completed yet, so that the machining path N in one pass unit is continued.
Electric discharge machining is continued while outputting the C code (step S
212). On the other hand, if the machining pass is the first pass, it means that the first contour pass 51 has been completed.
Proceed to 1 to output a consumption correction coefficient change code. When the consumption correction coefficient change code is output, the process returns to step S202 via step S209 without outputting the machining path NC code.

Next, in step S202, the first
When the entire machining pass is completed by the contour path 51, the electric discharge machining is completed, but when the entire machining pass is not completed,
Move on to processing of the second contour path 52 (step S20)
3).

In step S213, a machining area by one machining pass is calculated. Specifically, as shown in FIG. 4, a processing area 212 by the processing path 112 between the FGs is calculated. Note that the machining path 111 between AFs is a pick feed, and its amount is equal to the radius of the tool electrode 1.

In step S214, an actual machining area 82 is obtained. That is, the processing area 2 of the obtained processing path 112
An area where the 12 and the unprocessed area 72 overlap is calculated. In this case, since the work W has already been processed by the first contour path 51, the unprocessed area 72 is smaller than the state where the work W is solid. Therefore, the workpiece W is processed using a part of the diameter of the tool electrode 1. In addition,
Since the unprocessed region 72 has been recalculated in step S206, its value is used.

In step S215, the unprocessed area (not shown) is recalculated. Note that the recalculation step S215 of the unprocessed area does not have to be at this position, and may be performed at least immediately before step S214 of calculating the actual processed area.

In step S216, the average processing width is calculated by the average processing width calculation unit 903. The average processing width is
As shown in FIG. 7, it can be obtained by dividing the actual machining area 82 by the machining path length. The processing path length is calculated from the processing path stored in the processing path storage unit 801.
Since the tool electrode 1 has a cylindrical shape, the actual machining area 82
Are formed in an arc shape at both ends.
a) is regarded as a square shape having the same width as the other portions (82b in the figure), and the average processing width is determined.

In step S217, the optimum electrode consumption correction coefficient calculating section 904 calculates an optimum electrode consumption correction coefficient from the average processing width. The wear correction coefficient is obtained by a basic experiment from the average processing width and set as processing conditions.
The relationship between the average processing width and the electrode correction coefficient is as described above (see FIG. 6).

Next, since the optimum electrode wear correction coefficient has been obtained, electric discharge machining is actually performed based on this. In step S218, an electrode wear correction coefficient change code is output for each processing pass. With this electrode wear correction coefficient change code, the electrode wear correction coefficient (for example, the electrode wear correction coefficient for the first contour path) stored in the electrode wear correction coefficient storage unit 802 is changed to the electrode wear correction coefficient obtained above. I do.

In step S219, a machining path NC code is output for each pass based on the electrode wear correction coefficient, and the tool electrode 1 is moved while correcting the tool electrode wear. The wear correction of the tool electrode 1 is performed by the control device 7 having received the pass command and the electrode wear correction coefficient by controlling the Z-axis drive device 12. Then, while optimizing the electrode wear correction coefficient for each machining pass, electric discharge machining is performed until all machining passes are completed (step S202).

As described above, according to the electric discharge machining apparatus 100,
Taking into account the average machining width, the tool electrode 1 is compensated for consumption by calculating the optimum electrode consumption compensation coefficient for each machining pass or first contour pass. Swell is unlikely to occur. In addition, since the time and effort for the finishing processing can be omitted, the processing time can be reduced.

Embodiment 2 FIG. 8 is an explanatory diagram showing a method of calculating an electrode wear correction coefficient by the electric discharge machine according to the second embodiment of the present invention. The method for calculating the electrode wear correction coefficient according to the second embodiment is substantially the same as the method for calculating the electrode wear correction coefficient according to the first embodiment, except that the discharge gap is taken into account when calculating the machining area. . Except for this point, the configuration is the same as that of the first embodiment, and a description thereof is omitted.

As shown in FIG. 8, a discharge gap 1a is usually generated around the tool electrode 1. Discharge gap 1
The size a depends on the dielectric strength of the work material, the dielectric strength of the working fluid, dirt due to processing waste, voltage, and the like. The average discharge gap 1a is set for each electrical condition and work material. The size of the discharge gap 1a is determined by the electrical condition storage unit 8
03.

When calculating the machining areas 61 and 212 in steps S204 and S213 in FIG.
The double is added to the diameter D of the tool electrode 1. With this configuration, the actual processing areas 81 and 82 can be accurately calculated because the workpiece W is close to a state where the workpiece W is actually processed. Therefore, since a realistic average processing width can be obtained, the electrode consumption correction coefficient can be calculated more accurately. For this reason, steps and undulations are less likely to occur on the processing bottom surface.

Embodiment 3 FIG. 9 is an explanatory diagram showing a method of calculating an electrode wear correction coefficient by the electric discharge machine according to the third embodiment of the present invention. The method for calculating an electrode wear correction coefficient according to the third embodiment relates to a case where the method for calculating an electrode wear correction coefficient according to the first embodiment is used for an electric discharge machine that performs machining with tool electrodes having different diameters.

As shown in FIG. 9, in the case of an electric discharge machining apparatus using a small-diameter tool electrode 15 and a large-diameter tool electrode 16, the actual machining area 83 has a complicated shape. For example, when an island shape W1 as shown in FIG. 1 is formed, the periphery of the island shape W1 is processed by the small-diameter tool electrode 15, and the small-diameter tool electrode 1 is formed.
5 and the large diameter tool electrode 1
Process according to 6. For this reason, step S20 in FIG.
When the actual machining area 83 is calculated in 5 and 21, the actual machining area 83 has a distorted shape in which a part is missing. Further, both sides of the actual machining area 83 are semicircular. Therefore, FIG.
As shown in FIG.
The average processing width is calculated based on a.

First, the actual machining area 83 is obtained by removing the overlapping area between the remaining machining area and the machining area. Next, the area of the actual machining area 83 is calculated using an arbitrary calculation method. Then, an average processing width is obtained by dividing the obtained area by the processing path length. Other processes are as shown in FIG.

In this way, the tool electrodes 1 having different diameters can be used.
Even when 5 and 16 are used, the optimum electrode wear correction coefficient can be calculated, so that steps and undulations are less likely to occur on the processing bottom surface. Even when using three or more tool electrodes having different diameters, the actual processing area is regarded as a rectangle as described above,
An average processing width can be determined.

[0066]

As described above, according to the electric discharge machining apparatus and the electric discharge machining method of the present invention, an actual machining area to be actually machined is obtained, and from this actual machining area, for each machining pass or each contour pass. Since the average processing width is obtained and the optimum electrode consumption correction coefficient is obtained from the average processing width, it is possible to effectively suppress the variation in the processing amount on the processing bottom surface. As a result, steps and undulations on the processing bottom surface can be reduced. Further, since the dependence on the finishing processing is reduced, the processing time can be reduced.

Further, in the electric discharge machining apparatus and the electric discharge machining method of the present invention, when electric discharge machining is performed using the entire diameter of the tool electrode, an electrode wear correction coefficient is obtained for each contour path, and otherwise, for each machining path. To acquire the electrode wear correction coefficient. For this reason, the occurrence of steps and undulations on the processing bottom surface can be effectively suppressed.

Further, in the electric discharge machining apparatus and the electric discharge machining method according to the present invention, for the first contour path, the electrode wear correction coefficient is obtained for each contour path, and for the other second contour paths and machining paths, The electrode wear correction coefficient is obtained for each processing pass. For this reason, the occurrence of steps and undulations on the processing bottom surface can be effectively suppressed.

Further, in the electric discharge machining apparatus and the electric discharge machining method according to the present invention, the machining area is acquired in consideration of the electric discharge gap, so that the machining area can be acquired accurately. As a result, the electrode wear correction coefficient can be acquired more optimally, and the step and undulation of the bottom surface can be more effectively suppressed.

In the electric discharge machining apparatus and the electric discharge machining method of the present invention, the actual machining area is regarded as a rectangle, and then divided by the machining path length or the contour path length to obtain the average machining width. Therefore, even in the case of electric discharge machining having a complicated shape, steps and undulations on the machining bottom can be effectively suppressed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an electric discharge machine according to a first embodiment of the present invention.

FIG. 2 is a flowchart showing an electric discharge machining process by the electric discharge machine of FIG.

FIG. 3 is an explanatory diagram showing a processing region in a step in the flowchart shown in FIG. 2;

FIG. 4 is an explanatory diagram showing a processing region in a step in the flowchart shown in FIG. 2;

FIG. 5 is an explanatory diagram showing a method for calculating an average processing width.

FIG. 6 is an explanatory diagram showing a relationship between an average processing width and an electrode correction coefficient.

FIG. 7 is an explanatory diagram showing a method for calculating an average processing width.

FIG. 8 is an explanatory diagram showing a method of calculating an electrode wear correction coefficient by the electric discharge machine according to the second embodiment of the present invention;

FIG. 9 is an explanatory diagram showing a method for calculating an electrode wear correction coefficient by the electric discharge machine according to the third embodiment of the present invention;

FIG. 10 is an explanatory diagram showing a calculation method of an average processing width.

FIG. 11 is an explanatory view showing a conventional electric discharge machining method.

FIG. 12 is a diagram showing an example of E described in JP-A-5-345228.
FIG. 4 is an explanatory diagram of a correction method of a tool electrode in the DM device.

FIG. 13 is an explanatory diagram showing a horizontal movement locus of a tool electrode.

[Explanation of symbols]

Reference Signs List 100 electric discharge machine, 1 tool electrode, 2 electrode rotating device, 3 work table, 4 machining fluid, 5 machining tank, 6
Power supply for processing, 7 control device, 8 storage unit, 9 operation unit,
801 machining path storage section, 802 wear correction coefficient storage section, 803 electrical condition storage section, 901 remaining processing area calculation section, 902 processing area calculation section, 903 average processing width calculation section, 904 optimal wear correction coefficient calculation section, 10 X axis Drive, 11 Y axis drive, 12 Z axis drive.

Claims (10)

[Claims] An electric discharge machine for applying a pulse-like voltage between a tool electrode and a workpiece and performing electric discharge machining while correcting wear in the length direction of the tool electrode based on an electrode wear correction coefficient. An unprocessed area obtaining means for obtaining the unprocessed area each time processing is performed, a processing area obtaining means for obtaining the processed area from the tool electrode and the processing path, and an actual processing which is an overlapping area of the processed area and the unprocessed area. An actual machining area acquiring means for acquiring an actual machining area to be obtained, an average machining width acquiring means for dividing the actual machining area by a contour path length or a machining path length, and an average machining width acquiring means, based on the average machining width. An electric discharge machining apparatus comprising: an optimum electrode consumption correction coefficient acquisition unit for acquiring an optimum electrode consumption correction coefficient; and wherein the wear correction is performed using the acquired electrode consumption correction coefficient. Further, when performing electric discharge machining using the entire diameter of the tool electrode, a machining area is obtained for each contour path, and the actual machining area is divided by the contour path length to obtain an average machining width for the contour path. When the electrode wear correction coefficient is obtained and electric discharge machining is performed using a part of the diameter of the tool electrode, the machining area is acquired for each machining path and the actual machining area is divided by the machining path length. The electric discharge machining apparatus according to claim 1, wherein the electrode wear correction coefficient is obtained. Further, for the first contour path, a machining area is acquired in units of the contour path, and an electrode machining correction coefficient for the first contour path is calculated from an average machining width obtained by dividing the actual machining area by the contour path length. For the second contour path or the machining paths after the first contour path, the machining area is acquired in machining path units, and the normal electrode consumption is calculated from the average machining width obtained by dividing the actual machining area by the machining path length. The electric discharge machining apparatus according to claim 1, wherein a correction coefficient is obtained. 4. The apparatus according to claim 1, wherein the machining area acquiring means considers a discharge gap of a tool electrode when acquiring the machining area. Electric discharge machine. 5. The method according to claim 1, wherein the average processing width obtaining means obtains an average processing width by dividing the actual processing area into a rectangle and dividing the actual processing area by a processing path length or a contour path length. The electric discharge machine according to claim 1. 6. An electric discharge machining method for performing electric discharge machining while applying a pulsed voltage between a tool electrode and a workpiece and correcting the wear in the length direction of the tool electrode based on an electrode wear correction coefficient. An unprocessed area obtaining step for obtaining the unprocessed area each time the processing is performed, a processing area obtaining step for obtaining the processed area from the tool electrode and the processing path, and an actual processing that is an overlapping area of the processed area and the unprocessed area An actual machining area acquiring step of acquiring an actual machining area to be obtained, an average machining width acquiring step of dividing the actual machining area by a contour path length or a machining path length, and an average machining width acquiring step of acquiring the average machining width. An optimum electrode wear correction coefficient obtaining step of obtaining an optimum electrode wear correction coefficient, wherein the wear correction is performed using the obtained electrode wear correction coefficient. 7. In the case of electric discharge machining using the entire diameter of the tool electrode, a contour path machining area acquiring step of acquiring a machining area in contour path units, and an average machining width obtained by dividing the actual machining area by the contour path length. And a contour path electrode wear correction coefficient obtaining step of obtaining a contour path electrode wear correction coefficient from the above.If the electric discharge machining is performed using a part of the diameter of the tool electrode, a machining area is defined in each machining path. A machining path machining area acquiring step of acquiring, and a normal electrode consumption compensation coefficient acquiring step of acquiring a normal electrode consumption compensation coefficient from an average machining width obtained by dividing the actual machining area by the machining path length. The electric discharge machining method according to claim 6, wherein 8. A contour path machining area acquiring step of acquiring a machining area in units of the contour path, and a first contour path from an average machining width obtained by dividing the actual machining area by the contour path length. A first contour pass electrode wear correction coefficient obtaining step of obtaining a pass electrode wear correction coefficient; and a machining area for each of the second contour path or the first contour path. And a normal electrode wear correction coefficient obtaining step of obtaining a normal electrode wear correction coefficient from an average processing width obtained by dividing the actual processing area by the processing path length. The electric discharge machining method according to claim 6, wherein 9. The method according to claim 6, wherein, in the processing area obtaining step, a discharge gap of a tool electrode is taken into account when obtaining the processing area. Electric discharge machining method. 10. The method according to claim 1, wherein in the step of obtaining an average processing width, the actual processing area is regarded as a rectangle, and then divided by a processing path length or a contour path length to obtain an average processing width. The electric discharge machining method according to claim 6.