JP6972443B1 - Wire EDM, Shape Dimension Compensator, Wire EDM Method, Learning Equipment, and Inference Equipment - Google Patents

Abstract

A processing mechanism (30) in which a wire discharge processing apparatus (100) performs wire discharge processing on a workpiece having a plurality of plate thickness regions having different plate thicknesses on a processing path by using a voltage pulse from a wire electrode. A plate thickness estimator (48) that estimates the plate thickness of the workpiece during wire discharge machining, and the machining voltage during machining, machining energy during machining, machining speed during machining, and machining fluid are supplied to the wire electrodes. Based on the separation distance, which is the distance between the nozzle and the workpiece, and the plate thickness, the difference in machining dimensions between the plate thickness regions becomes smaller, and the wire electrode of the workpiece is straightened in the length direction. The voltage correction value, which is the correction value of the processing voltage, the pause time correction value, which is the correction value of the pause time of the voltage pulse, and the wire, which is the tension command to the wire electrode, so that the accuracy is high in each plate thickness region. It comprises a shape dimension compensator (35) for calculating a tension command, and the machining mechanism (30) is controlled using a voltage correction value, a pause time correction value, and a wire tension command.

Description

The present disclosure relates to a wire electric discharge machine, a shape size compensator, a wire electric discharge machine, a learning device, and an inference device that compensate for the size and shape of a workpiece after processing.

In the wire electric discharge machining apparatus, appropriate machining conditions differ depending on the plate thickness of the workpiece to be machined. Therefore, it is desired that the wire electric discharge machining apparatus selects an appropriate machining condition according to the plate thickness and executes the wire electric discharge machining.

In the wire electric discharge machining apparatus described in Patent Document 1, the electric condition strength is selected from the relationship between the plate thickness and the processing energy, and the wire electrode is prevented from being broken by switching to the electric condition corresponding to the electric condition strength. ..

Japanese Unexamined Patent Publication No. 9-290328

However, in the technique of Patent Document 1, when the workpiece is a thin plate, the removal volume in the machining progress direction is small and the machining speed is high, so that it is difficult for the electric discharge to fly to the side surface in the traveling direction. On the other hand, when the workpiece is a thick plate, the removal volume in the traveling direction is large and the processing speed is slow, so that the electric discharge tends to fly to the side surface in the traveling direction.

Therefore, in the technique of Patent Document 1, in the processing in which the plate thickness of the workpiece changes during processing when a large electric discharge machining energy is applied, the processing groove width becomes narrower in the thin plate thickness, and the thick plate thickness. Then, the machined groove width becomes thicker. As a result, for the workpiece whose plate thickness changes during processing, the processing dimensions differ depending on the plate thickness, and the accuracy of the processing dimensions deteriorates. Further, the wire electrode bends during wire electric discharge machining. Therefore, even within the region of the same plate thickness of the work piece, the machined groove width differs depending on the position of the wire electrode where the work piece is machined. The dimensions vary and the accuracy of the processed shape deteriorates.

The present disclosure has been made in view of the above, and is a wire electric discharge machining apparatus capable of improving the accuracy of machining dimensions and the accuracy of machining shapes even for workpieces whose plate thickness changes during machining. The purpose is to get.

In order to solve the above-mentioned problems and achieve the object, the wire electric discharge machine of the present disclosure has a voltage from a wire electrode with respect to a workpiece having a plurality of plate thickness regions having different plate thicknesses on the processing path. It is provided with a processing mechanism for performing wire electric discharge machining using a pulse and a plate thickness estimator for estimating the plate thickness of the workpiece during wire electric discharge machining. Further, in the wire discharge processing apparatus of the present disclosure, the processing voltage during processing, the processing energy during processing, the processing speed during processing, and the distance between the nozzle that supplies the processing liquid to the wire electrode and the workpiece are separated. Based on the distance and the plate thickness, the difference in processing dimensions between the plate thickness regions is small, and the straightness accuracy of the wire electrode of the workpiece in the length direction is high in each plate thickness region. It is provided with a shape dimension compensator for calculating a voltage correction value which is a correction value of a processing voltage, a pause time correction value which is a correction value of a pause time of a voltage pulse, and a wire tension command which is a tension command to a wire electrode. The machining mechanism is controlled using voltage correction values, pause time correction values, and wire tension commands.

The wire electric discharge machining apparatus according to the present disclosure has an effect that the accuracy of the machining dimension and the accuracy of the machining shape can be improved even for a workpiece whose plate thickness changes during machining.

A perspective view showing a configuration example of a wire electric discharge machine according to an embodiment. A perspective view showing another configuration example of the wire electric discharge machine according to the embodiment. The figure for demonstrating the structure of the workpiece machined by the wire electric discharge machining apparatus which concerns on embodiment. The figure for demonstrating the shape of the workpiece when it is machined without correcting the machining speed with respect to the plate thickness. The figure for demonstrating the shape of the workpiece when it is machined without correcting the bending of a wire electrode with respect to a plate thickness. A block diagram showing an example of a functional configuration of a wire electric discharge machine according to an embodiment. The figure for demonstrating the calculation process of the voltage correction value by the shape dimension compensator which concerns on embodiment. The figure for demonstrating the voltage correction value information used by the shape dimension compensator which concerns on embodiment. The figure for demonstrating the calculation process of the pause time correction value by the shape dimension compensator which concerns on embodiment. The figure for demonstrating the relationship between the amount of nozzle separation and the amount of bending of a wire electrode. The figure for demonstrating the relationship between the wire tension and the amount of bending of a wire electrode. A flowchart showing a processing procedure of wire electric discharge machining by the wire electric discharge machining apparatus according to the embodiment. A block diagram showing a configuration example of a learning device according to an embodiment. A flowchart showing a processing procedure of learning processing by the learning device according to the embodiment. A block diagram showing a configuration example of an inference device according to an embodiment. A flowchart showing a processing procedure of inference processing by the inference device according to the embodiment. The figure which shows the hardware configuration example which realizes the NC control device which concerns on embodiment.

Hereinafter, the wire electric discharge machining apparatus, the shape dimension compensator, the wire electric discharge machining method, the learning apparatus, and the inference apparatus according to the embodiment of the present disclosure will be described in detail with reference to the drawings.

Embodiment.
FIG. 1 is a perspective view showing a configuration example of a wire electric discharge machine according to an embodiment. The wire electric discharge machining device 100 includes a machining mechanism 30, a wire tension control device 31, a machining power supply 32, and an NC (Numerical Control) control device 33 which is a numerical control device.

The processing mechanism 30 includes a wire electrode bobbin 1, a wire electrode 2, a tension load device 3, an upper power supply electron 4, a lower power supply electron 5, an upper guide 6, a lower guide 12, and a surface plate 8. It is provided with a lower roller 13. Further, the processing mechanism 30 includes a wire electrode recovery box 10, a wire traveling speed control motor 9, an X-axis drive motor 11X, and a Y-axis drive motor 11Y.

Further, the wire tension control device 31 is connected to the machining power supply 32 and the NC control device 33, and the machining power supply 32 is connected to the NC control device 33. Further, the machining mechanism 30 is connected to the wire tension control device 31, the machining power supply 32, and the NC control device 33. In the following, two axes in a plane parallel to the upper surface of the plate-shaped surface plate 8 and orthogonal to each other are referred to as an X axis and a Y axis. Further, the axis orthogonal to the X-axis and the Y-axis is defined as the Z-axis. For example, the XY plane is a horizontal plane and the Z-axis direction is a vertical direction. In the following description, the plus Z direction may be referred to as an upward direction, and the minus Z direction may be referred to as a downward direction.

The wire electrode bobbin 1 is wound with the wire electrode 2 and supplies the wire electrode 2 to the tension load device 3. The wire electrode 2 is pulled out from the wire electrode bobbin 1 and sent to the tension load device 3. The tension load device 3 conveys the wire electrode 2 and applies a tension load to the wire electrode 2. The tension load device 3 sends the wire electrode 2 to the lower roller 13 via the upper power supply 4, the upper guide 6, the lower power supply 5, and the lower guide 12. The wire electrode 2 that has passed through the lower roller 13 is sent to the wire electrode recovery box 10 through the wire traveling speed control motor 9.

The upper guide 6 is arranged on the lower side of the upper power supply electron 4, the lower power supply electron 5 is arranged on the lower side of the upper guide 6, and the lower guide 12 is arranged on the lower side of the lower power supply electron 5. The upper power supply 4 and the lower power supply 5 are connected to the machining power supply 32, and a voltage is applied between the wire electrode 2 and the workpiece 7.

The upper guide 6 and the lower guide 12 support the position and inclination of the wire electrode 2 during the machining of the workpiece 7, which is a workpiece. An upper nozzle 81, which will be described later, is arranged on the lower side of the upper guide 6, and a lower nozzle 82, which will be described later, is arranged on the upper side of the lower power supply electron 5. The upper nozzle 81 supplies the machining fluid to the lower side of the wire electrode 2, and the lower nozzle 82 supplies the machining fluid to the upper side of the wire electrode 2. The workpiece 7 is machined between the upper nozzle 81 and the lower nozzle 82.

The wire electric discharge machining apparatus 100 of the present embodiment wire electric discharge machining the workpiece 7 having a step. That is, the workpiece 7 has various plate thicknesses for each plate thickness region. In other words, the workpiece 7 has a plurality of plate thickness regions having different plate thicknesses on the processing path. For example, in the workpiece 7, the first plate thickness region of the plate thickness regions that are the workpiece regions is the first plate thickness, and the second plate thickness region adjacent to the first plate thickness region. Is the second plate thickness, and the first plate thickness region and the second plate thickness region are continuously wire electric discharged. The workpiece 7 is placed on the surface plate 8. The surface plate 8 is provided with a hole for passing the wire electrode 2.

The lower roller 13 conveys the wire electrode 2 after processing the workpiece 7 on the surface plate 8. The wire traveling speed control motor 9 is a recovery roller and generates a driving force for transporting the wire electrode 2. The wire electrode recovery box 10 is a box for collecting the wire electrode 2 sent from the wire traveling speed control motor 9. The X-axis drive motor 11X drives the surface plate 8 in the X-axis direction, and the Y-axis drive motor 11Y drives the surface plate 8 in the Y-axis direction.

The wire tension control device 31 is connected to the tension load device 3, and controls the wire tension, which is the tension of the wire electrode 2, by controlling the tension load device 3. The processing power supply 32 is connected to the upper power supply 4 and the lower power supply 5, and by controlling the upper power supply 4 and the lower power supply 5, a discharge is generated between the workpiece 7 and the wire electrode 2. To generate.

The machining power supply 32 has a machining voltage detector 45 and a machining energy detector 46, which will be described later. The machining power supply 32 sends the machining voltage detected by the machining voltage detector 45 and the machining energy detected by the machining energy detector 46 to the NC control device 33. Further, the processing power supply 32 uses the voltage correction value (hereinafter referred to as voltage correction value) and the voltage pulse pause time correction value (hereinafter referred to as pause time correction value) sent from the NC control device 33. Controls the upper power supply 4 and the lower power supply 5.

The NC control device 33 controls the machining mechanism 30, the machining power supply 32, and the wire tension control device 31. The NC control device 33 is connected to, for example, the X-axis drive motor 11X and the Y-axis drive motor 11Y. The NC control device 33 controls the position of the surface plate 8 in the X-axis direction and the position in the Y-axis direction by sending an axis movement command to the X-axis drive motor 11X and the Y-axis drive motor 11Y. As a result, the NC control device 33 controls the distance between the workpiece 7 placed on the surface plate 8 and the wire electrode 2, and the voltage between the poles between the workpiece 7 and the wire electrode 2. To control.

Further, the NC control device 33 is connected to the wire traveling speed control motor 9 and controls the wire traveling speed control motor 9. In FIG. 1, the connection line between the NC control device 33 and the wire traveling speed control motor 9 is not shown.

The NC control device 33 calculates the wire tension command based on the machining voltage detected by the machining voltage detector 45 and the machining energy detected by the machining energy detector 46. The wire tension command is a command for controlling the tension of the wire electrode 2. The NC control device 33 sends the calculated wire tension command to the wire tension control device 31.

Further, the NC control device 33 calculates the voltage correction value and the pause time correction value based on the processing voltage detected by the processing voltage detector 45 and the processing energy detected by the processing energy detector 46. The NC control device 33 sends the calculated voltage correction value and pause time correction value to the processing power supply 32.

The wire discharge processing apparatus 100 moves the platen 8 in the X-axis direction and the Y-axis direction by the X-axis drive motor 11X and the Y-axis drive motor 11Y, and the workpiece 7 placed on the platen 8 and the wire electrode. The distance between 2 and 2 is controlled to a specific distance at which wire discharge is possible. As a result, the wire electric discharge machine 100 performs electric discharge machining of the workpiece 7 by the wire electrode 2. Hereinafter, a case where the workpiece 7 is moved in the X-axis direction to perform wire electric discharge machining of the workpiece 7 will be described.

The wire electric discharge machine 100 may move the wire electrode 2 instead of the surface plate 8. FIG. 2 is a perspective view showing another configuration example of the wire electric discharge machine according to the embodiment.

The wire electric discharge machining apparatus 101 shown in FIG. 2 includes a machining mechanism 34 instead of the machining mechanism 30 as compared with the wire electric discharge machining apparatus 100 shown in FIG. The machining mechanism 34 does not include the X-axis drive motor 11X and the Y-axis drive motor 11Y as compared with the machining mechanism 30. The wire electric discharge machine 101 sends an axis movement command to the upper guide 6 and the lower guide 12. As a result, in the wire electric discharge machine 100, the upper guide 6 and the lower guide 12 move in the X-axis direction and the Y-axis direction.

As described above, the wire electric discharge machine 100 shown in FIG. 1 is a method of moving the surface plate 8 by the axis movement command from the NC control device 33, and the wire electric discharge machine 101 shown in FIG. 2 is an NC control device. This is a method of moving the upper guide 6 and the lower guide 12 by the axis movement command from 33. In the following description, the wire electric discharge machine 100 shown in FIG. 1 will be described.

Here, the reason why the processing dimensions and the processing shape vary in the processing of the workpiece 7 having various plate thicknesses for each plate thickness region will be described. The processing dimension is the dimension of the workpiece 7 after processing, and the processing shape is the shape of the workpiece 7 after processing. In the present embodiment, the machining dimension is the dimension of the workpiece 7 in the Y-axis direction, that is, the dimension when viewed from the Z-axis direction, and the machining shape is the dimension when the workpiece 7 is viewed from the X-axis direction. The shape of. Since the workpiece 7 has a height in the Z-axis direction, the machining dimensions differ depending on the height. The shape of the workpiece 7 is determined by the machining dimensions for each height.

FIG. 3 is a diagram for explaining the structure of the workpiece to be machined by the wire electric discharge machine according to the embodiment. FIG. 3 illustrates a region in the vicinity of a portion of the workpiece 7 to be machined by the wire electrode 2. Since the workpiece 7 is machined in the X-axis direction, a groove parallel to the X-axis direction is formed in the workpiece 7.

The workpiece 7 is repeatedly machined in the X-axis direction a plurality of times. For example, the workpiece 7 is rough-processed by the first processing, semi-finishing processing is performed by the second processing, and finishing processing is performed by the third processing.

The workpiece 7 has, for example, a first plate thickness region 21 having a first plate thickness, a second plate thickness region 22 having a second plate thickness, and a third plate thickness. It is composed of a third plate thickness region 23 and a fourth plate thickness region 24 having a fourth plate thickness. The first plate thickness is, for example, 200 mm, the second plate thickness is, for example, 150 mm, the third plate thickness is, for example, 100 mm, and the fourth plate thickness is, for example, 50 mm. Hereinafter, any one of the first plate thickness region 21, the second plate thickness region 22, the third plate thickness region 23, and the fourth plate thickness region 24 may be referred to as a plate thickness region.

When the wire electric discharge machine 100 processes the workpiece 7 in the order of the first plate thickness region 21, the second plate thickness region 22, the third plate thickness region 23, and the fourth plate thickness region 24. The plate thickness to be machined changes in the order of the first plate thickness, the second plate thickness, the third plate thickness, and the fourth plate thickness. The workpiece 7 is machined by a wire electrode 2 between the upper nozzle 81 and the lower nozzle 82. The distance between the upper nozzle 81 and the lower nozzle 82 is, for example, 310 mm.

FIG. 4 is a diagram for explaining the shape of the workpiece when it is machined without correcting the machining speed with respect to the plate thickness. FIG. 4 shows the processed shape of the first plate thickness region 21 and the fourth plate thickness region 24 when the workpiece 7 is viewed from the upper surface.

In the processing in which the plate thickness changes, if the processing is performed without considering the plate thickness, the removal volume of the workpiece 7 in the processing progress direction is small in the fourth plate thickness region 24, which is a region where the plate thickness is thin. Since the machining speed is high, it is difficult for the discharge to fly to the side surface in the machining progress direction. On the other hand, in the first plate thickness region 21 where the plate thickness is thick, the removal volume of the workpiece 7 in the processing progress direction is large and the processing speed is slow, so that the electric discharge tends to fly to the side surface in the processing progress direction.

Therefore, in the fourth plate thickness region 24 where the plate thickness is thin, the amount of the workpiece 7 to be machined is small, and in the first plate thickness region 21 where the plate thickness is thick, the amount of the workpiece 7 to be machined is reduced. Will increase. As a result, there arises a problem that the machined groove width is narrow in the region where the plate thickness is thin, the machined groove width is large in the region where the plate thickness is thick, and the processing dimensions are different for each plate thickness region. The machining groove width, that is, the machining dimension is the vibration due to the running of the wire electrode 2, the amount of separation from the upper nozzle 81 to the workpiece 7, the amount of separation from the lower nozzle 82 to the workpiece 7, the machining voltage, and the input. It changes depending on the discharge energy.

Further, even within the same plate thickness region, the amount of bending of the wire electrode 2 differs depending on the height of the workpiece 7, so that the processing progress speed differs depending on the height of the workpiece 7. That is, the processing progress speed differs depending on the amount of separation from the upper nozzle 81 to the workpiece 7 and the amount of separation from the lower nozzle 82 to the workpiece 7. The nozzle separation amount is the separation distance between the upper nozzle 81 and the workpiece 7, and the separation distance between the lower nozzle 82 and the workpiece 7. Since the workpiece 7 has various plate thickness regions, the nozzle separation amount differs depending on the plate thickness region. Therefore, if the workpiece 7 is machined without correcting the machining conditions such as the machining speed, the machining shape will vary.

The wire electric discharge machining apparatus 100 of the present embodiment sets machining conditions such as a machining voltage so that the machining dimensional difference and the machining shape difference in each region in the first machining can be corrected in the second and subsequent machining. adjust. That is, if the machining dimension difference or machining shape difference generated in the first machining is large, the machining dimension and machining shape may not be completely corrected. Therefore, the wire electric discharge machining apparatus 100 is used at the time of the first machining. , EDM is performed according to the change in plate thickness so that the groove width is constant to some extent. In other words, in the wire electric discharge machining apparatus 100, the difference in the machining groove width between the plate thickness regions and the variation in the machining shape within the plate thickness region caused by the change in the plate thickness approach to a constant value at the time of the first machining. Process to.

The NC control device 33 of the embodiment calculates a wire tension command, a voltage correction value, and a pause time correction value based on the machining voltage, the electric discharge machining energy per unit time, and the nozzle separation amount. The NC control device 33 has a wire tension command and a voltage such that the difference in machining dimensions and the difference in machining shape between different plate thickness regions is small for the workpiece 7 having various plate thicknesses for each plate thickness region. Calculate the correction value and the pause time correction value.

The work piece 7 has various plate thickness regions, and the amount to be machined differs at each position from the bottom surface to the top surface of the work piece 7. Therefore, the workpiece 7 has different dimensions after machining depending on the height from the bottom surface of the workpiece 7. In the present embodiment, the average value of the dimensions after machining for each height from the bottom surface of the workpiece 7 in one plate thickness region is referred to as a machining dimension. The processed dimension may be the median value of the processed dimension for each height from the bottom surface of the workpiece 7 in one plate thickness region. The NC control device 33 calculates a wire tension command, a voltage correction value, and a pause time correction value so that the machining dimensions do not vary between the plate thickness regions in each plate thickness region of the workpiece 7.

In the present embodiment, the processed shape of the workpiece 7 is indicated by the straightness accuracy of the workpiece 7 in the Z-axis direction. The straightness accuracy corresponds to the variation in the dimensional accuracy of the machining dimension of the workpiece 7 corresponding to the bending amount of the wire electrode 2 during the wire electric discharge machining. Since the bending of the wire electrode 2 is a bending in a direction perpendicular to the Z-axis direction, a bending component in the X-axis direction and a bending component in the Y-axis direction are included. Since the bending component in the Y-axis direction affects the machining dimensions of the workpiece 7 in the Y-axis direction, the bending component in the Y-axis direction will be described below.

FIG. 5 is a diagram for explaining the shape of the workpiece when it is machined without correcting the bending of the wire electrode with respect to the plate thickness. The horizontal axis of FIG. 5 is the machining dimension of the workpiece 7 in the Y-axis direction, and the vertical axis is the height of the workpiece 7. As shown in FIG. 5, the machining dimensions of the workpiece 7 in the Y-axis direction differ depending on the height of the workpiece 7.

The dimension curve 65 is the machining dimension in the first plate thickness region 21, and the dimension curve 66 is the machining dimension in the second plate thickness region 22. The dimension curve 67 is the processing dimension in the third plate thickness region 23, and the dimension curve 68 is the processing dimension in the fourth plate thickness region 24. For example, in the first plate thickness region 21, the height of the workpiece 7 is from 0 to 200 mm. Then, in the first plate thickness region 21, the machining dimension is small in the central region of the workpiece 7 in the Z-axis direction, which is a portion where the amount of bending of the wire electrode 2 is large. Then, the machining dimension is reduced in the end region in the Z-axis direction of the workpiece 7, which is a portion where the amount of bending of the wire electrode 2 is reduced.

That is, even within one plate thickness region, the workpiece 7 is machined in the upper and lower end regions of the wire electrode 2 due to the bending of the wire electrode 2 (hereinafter referred to as a wire end machined portion). ) And the portion processed in the central region of the wire electrode 2 (hereinafter referred to as the wire central processed portion) differ in the amount processed.

As a result, the bending of the wire electrode 2 is larger at the wire center machined portion than at the wire end machined portion, so that the area to be machined becomes wider. As a result, the amount of processing at the wire center processed portion is larger than that at the wire end processed portion, so that the post-machining dimension becomes smaller. As described above, even within one plate thickness region, the work piece 7 has a variation in post-working dimensions depending on the height from the bottom surface of the work piece 7 due to the bending of the wire electrode 2. The variation in the processing dimension within this one plate thickness region corresponds to the variation in the processing shape.

The NC control device 33 stores the dimensional curve information which is the information of the dimensional curves 65 to 68, and when the workpiece 7 is machined, the machining voltage, the rest time, and the wire tension are set based on the dimensional curve information. Control.

Ideally, the machining dimensions of the workpiece 7 in a plane parallel to the XY plane (in the Y-axis direction in the present embodiment) within one plate thickness region of the workpiece 7 are at each height of the workpiece 7. It is the same. Therefore, the NC control device 33 controls the wire tension command so as to suppress the variation in the machining dimension in the Y-axis direction within one plate thickness region of the workpiece 7, that is, to suppress the variation in the machining shape. Calculate the voltage correction value and the pause time correction value. Specifically, the NC control device 33 has a wire tension command, a voltage correction value, and a pause so that the amount of deflection in the Y-axis direction, which is the direction perpendicular to the X-axis direction, which is the machining progress direction of the wire electrode 2, is small. Calculate the time correction value. In other words, the NC control device 33 calculates the wire tension command, the voltage correction value, and the pause time correction value so as to increase the straightness accuracy in each plate thickness region of the workpiece 7.

The smaller the amount of bending of the wire electrode 2 in the Y-axis direction, the higher the straightness accuracy of the wire electrode 2, the smaller the error in the machining dimensions between the wire end machined part and the wire center machined part, and the work piece 7 The straightness accuracy of is increased. As a result, the error of the machined shape is reduced, and the NC control device 33 can improve the accuracy of the machined shape.

The higher the accuracy of the machined dimensions, the more overlap of the dimension curves 65-68. Further, as the accuracy of the processing dimension becomes higher, the bending amount of the dimension curve 65-68 decreases, and the dimension curve 65-68 approaches a straight line parallel to the vertical axis of FIG.

The wire electric discharge machining apparatus 100 uses the following four parameters that determine the machining shape at the time of machining.
(A) Machining voltage (B) Electric discharge machining energy per unit time (C) Nozzle separation amount (D) Wire tension

The above four parameters have the following effects on the processing into the workpiece 7, respectively.
-The machining voltage affects the machining groove width (machining dimensions, straightness accuracy).
-Electrical discharge machining energy per unit time affects straightness accuracy and machining speed.
-The amount of nozzle separation affects the electric discharge machining energy.
-The wire tension affects the straightness accuracy due to the bending of the wire electrode 2.

The low processing voltage corresponds to the short distance between the wire electrode 2 and the workpiece 7. When adjusting the machining voltage, the wire electric discharge machining apparatus 100 adjusts the distance between the wire electrode 2 and the workpiece 7 by adjusting the feed rate of the wire electrode 2 in the machining progress direction. For example, when the wire electric discharge machining apparatus 100 lowers the machining voltage, the wire electrode 2 reduces the distance between the wire electrode 2 and the workpiece 7 by increasing the feed rate of the wire electrode 2 in the machining progress direction. In this case, since the removal volume of the side surface in the machining progress direction is reduced, the machining dimension of the workpiece 7 becomes large. On the other hand, when the wire electric discharge machining apparatus 100 increases the machining voltage, the wire electrode 2 reduces the feed rate in the machining progress direction to increase the distance between the wire electrode 2 and the workpiece 7. In this case, since the removal volume of the side surface in the machining progress direction becomes large, the machining dimension of the workpiece 7 becomes small. The feed rate of the wire electrode 2 in the machining progress direction corresponds to the machining speed.

When the feed speed in the machining progress direction is increased, the force that tries to separate the wire electrode 2 from the workpiece 7 due to the explosive force generated by the electric discharge causes the wire electrode 2 to be separated by the electrostatic attraction due to the current flowing through the wire electrode 2. Since the force is larger than the force for approaching the workpiece 7, the machined surface has a shape in the bulging direction. On the other hand, when the feed rate in the machining progress direction is lowered, the electrostatic attraction becomes superior to the explosive force generated by the discharge, so that the machining surface shape is in the recessed direction.

The wire electric discharge machining apparatus 100 calculates the electric discharge machining energy based on the energy per one pulse of the electric discharge pulse and the number of pulses. In the wire electric discharge machining apparatus 100, when the electric discharge machining energy is lowered, the amount of bending of the wire electrode 2 is reduced, so that the straightness accuracy can be improved. Further, in the wire electric discharge machining apparatus 100, if the electric discharge machining energy is increased, the machining amount can be increased, so that the machining speed can be increased.

The wire electric discharge machine 100 detects the nozzle separation amount by the nozzle separation amount detector 49 described later, or the setting input IF (InterFace, interface) 20 described later receives from the user.

As the amount of nozzle separation increases, the amount of machining fluid supplied to the poles between the wire electrode 2 and the workpiece 7 decreases, so the electric discharge machining energy that can be charged up to the disconnection limit of the wire electrode 2 decreases. Further, as the wire tension is higher, the bending of the wire electrode 2 is reduced, so that the straightening accuracy is improved.

The wire electric discharge machining apparatus 100 controls machining so that the machining dimensions for each plate thickness region to be machined and the machining shape within each plate thickness region approach a constant value. Therefore, the manufacturer of the wire electric discharge machining apparatus 100 obtains in advance the results of each machining dimension and each machining shape when machining is performed with various combinations of the parameters (A) to (D) above. .. The manufacturer of the wire electric discharge machine 100 manufactures the shape dimension compensator 35 described later by formulating the relationship between each of the above parameters (A) to (D) and the machined dimension and the machined shape. The shape dimension compensator 35 is arranged in the NC control device 33, and calculates a wire tension command, a voltage correction value, and a pause time correction value.

That is, the manufacturer of the wire electric discharge machining apparatus 100 uses a formulated function to approach the minimum machining dimensional difference between the plate thickness regions, and the straightness accuracy difference, which is the machining shape, approaches the minimum within each plate thickness region. A control model is constructed and set in the shape dimension compensator 35. This control model corresponds to the control by the shape dimension compensator 35. As a result, the shape dimension compensator 35 is based on the machining dimensions and straightness accuracy of the workpiece 7 when wire electric discharge machining is performed with a plurality of combinations of machining voltage, electric discharge machining energy, nozzle separation amount, and wire tension. The voltage correction value, the pause time correction value, and the wire tension command are calculated using the control model set in the above.

The shape dimension compensator 35 is set with voltage correction value information 77, energy correction value information, and first to third correspondence information, which will be described later, based on the processing result of the wire electric discharge machining apparatus 100 in advance. NS. In the prior machining process by the wire electric discharge machining device 100, in addition to the parameters (A) to (D) above, parameters that affect the machining shape such as the diameter of the wire electrode 2 and the material of the workpiece 7. May be combined in various ways. In this case, the manufacturer of the wire electric discharge machine 100 constructs a control model for each diameter of the wire electrode 2 and for each material of the workpiece 7, and sets the control model in the shape dimension compensator 35.

The shape and dimension compensator 35 uses a control model corresponding to at least one of the diameter of the wire electrode 2 and the material of the workpiece 7 specified by the user. The shape dimension compensator 35 calculates a wire tension command, a voltage correction value, and a pause time correction value based on the processing voltage, processing energy, processing speed, nozzle separation amount, and the like during processing.

FIG. 6 is a block diagram showing a functional configuration example of the wire electric discharge machine according to the embodiment. The machining power supply 32 includes a machining voltage detector 45, a machining energy detector 46, a feedback controller 43, and arithmetic units 41 and 42. The NC control device 33 includes a plate thickness estimator 48, a nozzle separation amount detector 49, a setting input IF 20, and a shape dimension compensator 35.

In the processing power supply 32, the arithmetic unit 41 is connected to the arithmetic unit 42, and the arithmetic unit 42 is connected to the feedback controller 43. Further, the feedback controller 43 is connected to the processing mechanism 30. Specifically, the feedback controller 43 is connected to the upper power supply electron 4 and the lower power supply electron 5.

Further, the machining mechanism 30 is connected to a machining voltage detector 45, a machining energy detector 46, a wire tension control device 31, a nozzle separation amount detector 49, and a plate thickness estimator 48. The machining voltage detector 45 is connected to the plate thickness estimator 48 and the shape dimension compensator 35. The machining energy detector 46 is connected to the plate thickness estimator 48 and the shape dimension compensator 35. The shape dimension compensator 35 is connected to a plate thickness estimator 48, a nozzle separation amount detector 49, a setting input IF 20, a calculator 41, and a wire tension control device 31.

The wire tension control device 31 controls the tension load device 3 of the processing mechanism 30. Further, the NC control device 33 controls the X-axis drive motor 11X, the Y-axis drive motor 11Y, and the like of the processing mechanism 30.

The machining voltage detector 45 is connected to the wire electrode 2 via the upper power supply electron 4 or the lower power supply electron 5, and is also connected to the workpiece 7. The machining voltage detector 45 detects the machining voltage between the electrodes between the wire electrode 2 and the workpiece 7 during machining. The machining voltage detected by the machining voltage detector 45 corresponds to the distance between the wire electrode 2 and the workpiece 7. The machining voltage detector 45 sends the detected machining voltage to the calculator 42, the plate thickness estimator 48, and the shape and dimension compensator 35.

The machining energy detector 46 is connected to the wire electrode 2 via the upper power supply electron 4 or the lower power supply electron 5, and is also connected to the workpiece 7. The machining energy detector 46 detects a discharge pulse generated between the wire electrode 2 and the workpiece 7 during machining. The machining energy detector 46 calculates the discharge machining energy based on the energy per one pulse of the discharge pulse and the number of pulses. The machining energy detector 46 sends electric discharge machining energy to the calculator 42, the plate thickness estimator 48, and the shape dimension compensator 35.

The arithmetic unit 41 receives a command voltage and a pause time from the NC control device 33. The command voltage is a command value of the voltage used for wire electric discharge machining. The calculator 41 receives the voltage correction value and the pause time correction value sent from the shape dimension compensator 35. The voltage correction value is a correction value for correcting the command voltage received by the arithmetic unit 41 from the NC control device 33. The pause time correction value is a correction value for correcting the pause time received by the arithmetic unit 41 from the NC control device 33. The voltage correction value and the pause time correction value are correction values for improving the accuracy of the machining dimensions and the accuracy of the machining shape for the workpiece 7 having a plurality of plate thickness regions having different plate thicknesses on the machining path. Is.

The calculator 41 subtracts the voltage correction value and the pause time correction value from the received command voltage and pause time, and sends the voltage correction value and the pause time correction value to the calculator 42. The arithmetic unit 41 may be arranged in the NC control device 33.

The calculator 42 subtracts the current machining voltage sent from the machining voltage detector 45 from the command voltage sent from the calculator 41 and sends it to the feedback controller 43. Further, the arithmetic unit 42 subtracts the current electric discharge machining energy transmitted from the machining energy detector 46 from the pause time sent from the arithmetic unit 41 and sends it to the feedback controller 43.

The feedback controller 43 controls the machining mechanism 30 using the result calculated by the arithmetic unit 42. Specifically, the feedback controller 43 corrects the position in the X-axis direction and the position in the Y-axis direction of the surface plate 8 by sending an axis movement command to the X-axis drive motor 11X and the Y-axis drive motor 11Y. As a result, the feedback controller 43 controls the machining voltage, electric discharge machining energy, and the like with respect to the machining mechanism 30.

The X-axis drive motor 11X and the Y-axis drive motor 11Y of the processing mechanism 30 are connected to the encoder, respectively, and the encoder detects the processing speed and sends it to the plate thickness estimator 48.

The plate thickness estimator 48 is based on the machining speed sent from the machining mechanism 30, the machining voltage sent from the machining voltage detector 45, and the electric discharge machining energy sent from the machining energy detector 46. , Estimate the plate thickness of the workpiece 7. The plate thickness estimator 48 estimates the plate thickness of the processed portion of the workpiece 7 in the processing in which the plate thickness changes. The plate thickness estimator 48 sends the estimated plate thickness to the shape dimension compensator 35 as a plate thickness estimated value.

The nozzle separation amount detector 49 detects the nozzle separation amount from the processing mechanism 30 during processing and sends it to the shape dimension compensator 35. The setting input IF 20 receives the reference plate thickness input by the user and sends it to the shape dimension compensator 35. The reference plate thickness is a plate thickness that is used as a reference for processing dimensions. The wire electric discharge machine 100 processes a plate thickness region other than the reference plate thickness so that the workpiece 7 has the processing dimensions at the reference plate thickness.

For example, when the shape dimension compensator 35 stores the information of the dimension curves 65 to 68 as the dimension curve information, when 200 mm is specified as the reference plate thickness, the shape dimension compensator 35 has the dimension curve 65 of 200 mm. Controls the machining so that is close to parallel to the vertical axis. That is, the shape dimension compensator 35 calculates the voltage correction value, the rest time correction value, and the wire tension command so that the dimension curve 65 of 200 mm approaches parallel to the vertical axis.

Further, the shape dimension compensator 35 calculates a voltage correction value, a pause time correction value, and a wire tension command so that the machined dimension of 50 mm to 150 mm approaches the dimension curve 65 which is brought closer to parallel to the vertical axis.

When the reference plate thickness is not specified, the shape dimension compensator 35 controls the processing so as to approach the processing dimension (dimension curve) of the specific plate thickness. The shape dimension compensator 35 controls machining so as to approach the machining dimension of the thinnest plate thickness, for example.

The setting input IF 20 may receive the nozzle separation amount from the user and send it to the shape dimension compensator 35. In this case, the NC control device 33 does not have to have the nozzle separation amount detector 49.

The shape dimension compensator 35 issues a voltage correction value, a pause time correction value, and a wire tension command based on the processing voltage, processing energy, processing speed, plate thickness estimation value, nozzle separation amount, and reference plate thickness during processing. calculate.

The shape dimension compensator 35 sends a voltage correction value and a pause time correction value to the calculator 41, and sends a wire tension command to the wire tension control device 31. The wire tension control device 31 controls the machining mechanism 30 according to the wire tension command. Specifically, the wire tension control device 31 controls the tension load device 3 according to the wire tension command.

As described above, the shape dimension compensator 35 is based on the machining voltage during machining, the machining energy during machining, the machining speed during machining, the estimated plate thickness during machining, the nozzle separation amount during machining, and the reference plate thickness. Since the voltage correction value, the pause time correction value, and the wire tension command are calculated, the accuracy of the machining dimensions and the accuracy of the machining shape in the rough machining, which is the first machining, can be improved.

Here, the details of the parameters (A) to (D) described above will be described. First, the correction of the processing voltage according to the estimated plate thickness will be described. The shape dimension compensator 35 calculates the voltage correction value of the processing voltage based on the plate thickness estimated value.

FIG. 7 is a diagram for explaining a voltage correction value calculation process by the shape dimension compensator according to the embodiment. FIG. 7 shows the configuration of the voltage correction value calculation unit 85 included in the shape dimension compensator 35.

The voltage correction value calculation unit 85 includes arithmetic units 75 and 76. The arithmetic unit 75 calculates a plate thickness corresponding voltage correction value based on the plate thickness estimated value and sends it to the arithmetic unit 76. The plate thickness corresponding voltage correction value is a correction value of the processing voltage according to the plate thickness estimated value. The calculator 75 calculates the plate thickness corresponding voltage correction value by using the voltage correction value information indicating the correspondence relationship between the plate thickness estimated value and the plate thickness corresponding voltage correction value.

FIG. 8 is a diagram for explaining voltage correction value information used by the shape dimension compensator according to the embodiment. In the graph of the voltage correction value information 77 shown in FIG. 8, the horizontal axis is the plate thickness estimated value, and the vertical axis is the plate thickness corresponding voltage correction value. In the voltage correction value information 77, the voltage correction value corresponding to the plate thickness is 0 for the low plate thickness, and the voltage correction value corresponding to the plate thickness increases from the specific plate thickness in proportion to the thickness of the plate, and the specific plate is used. Above the thickness, the voltage correction value corresponding to the plate thickness is not changed. When the possibility that the wire electrode 2 is broken is low, the voltage correction value corresponding to the plate thickness may be increased even if the plate thickness is more than a specific plate thickness.

The calculator 75 calculates the plate thickness corresponding voltage correction value based on the voltage correction value information 77 and the plate thickness estimated value. The voltage correction value information 77 may be a mathematical formula showing the correspondence between the plate thickness estimated value and the plate thickness corresponding voltage correction value, or may be a data table.

The calculator 76 calculates the voltage correction value by adding the plate thickness corresponding voltage correction value to the measured processing voltage which is the measured processing voltage. The calculator 76 sends the voltage correction value to the calculator 41. In this way, the voltage correction value calculation unit 85 corrects the processing voltage with respect to the plate thickness estimated value. In the thick plate region, the processing speed becomes slow, and the bending of the wire electrode 2 widens the gap between the plate thickness region and the side surface of the workpiece 7, resulting in low straightness accuracy. Therefore, the voltage correction value calculation unit 85 corrects the processing speed by calculating the voltage correction value for correcting the processing voltage to be high in the plate thickness region where the plate thickness is thick. As a result, the voltage correction value calculation unit 85 suppresses the difference in processing dimensions between the thin plate thickness region and the thick plate thickness region.

Next, the correction of the electric discharge machining energy according to the estimated plate thickness will be described. The shape dimension compensator 35 calculates a pause time correction value for correcting the electric discharge machining energy based on the plate thickness estimation value.

FIG. 9 is a diagram for explaining the calculation process of the pause time correction value by the shape dimension compensator according to the embodiment. FIG. 9 shows the configuration of the pause time correction value calculation unit 86 included in the shape dimension compensator 35.

The pause time correction value calculation unit 86 has arithmetic units 63, 64, 80. The calculator 63 calculates the target electric discharge machining energy based on the estimated plate thickness and sends it to the calculator 64. The target electric discharge machining energy is a target value of electric discharge machining energy according to the estimated plate thickness. The calculator 63 calculates the target electric discharge machining energy by using the energy correction value information indicating the correspondence relationship between the plate thickness estimated value and the target electric discharge machining energy.

The arithmetic unit 64 calculates the electric discharge machining energy obtained by subtracting the target electric discharge machining energy from the current electric discharge machining energy, and sends the electric discharge machining energy to the arithmetic unit 80. The arithmetic unit 80 calculates the pause time correction value based on the electric discharge machining energy received from the arithmetic unit 64. The calculator 80 calculates the pause time correction value by the combination of the proportional control and the integral control. In this way, the arithmetic unit 80 sets the target electric discharge machining energy based on the calculated plate thickness estimation value, and calculates the pause time correction value so that the target electric discharge machining energy and the current electric discharge machining energy match. By doing so, the pause time is controlled.

Next, the wire tension command or the voltage correction value according to the nozzle separation amount will be described. The shape dimension compensator 35 calculates a wire tension command or a voltage correction value for correcting the machining voltage based on the nozzle separation amount.

Since the wire electrode 2 bends due to the influence of discharge reaction force, electrostatic attraction, etc. during machining, the straightness accuracy, that is, the shape accuracy of the workpiece 7 differs depending on the installation height of the workpiece 7. .. FIG. 10 is a diagram for explaining the relationship between the nozzle separation amount and the wire electrode deflection amount. In FIG. 10, the position of the lower nozzle 82 is the height 0, and the position of the upper nozzle 81 is the height T5.

The work piece 7D is a work piece machined by the wire electrode 2 in the region from height 0 to height T1. Further, the workpiece 7C is a workpiece processed by the wire electrode 2 in the region from the height T2 (> T1) to the height T3 (> T2). Further, the workpiece 7B is a workpiece processed by the wire electrode 2 in the region from the height T4 (> T3) to the height T5 (> T4).

The nozzle separation amount of the workpiece 7D is a distance R3 from the upper nozzle 81 and 0 from the lower nozzle 82. The nozzle separation amount of the workpiece 7C is a distance R2a from the upper nozzle 81 and a distance R2b from the lower nozzle 82. The nozzle separation amount of the workpiece 7B is 0 from the upper nozzle 81 and a distance R1 from the lower nozzle 82. R2a and R2b are both smaller values than R1 and R3.

As shown in FIG. 10, during machining, the wire electrode 2 bends in the Y-axis direction, which is a direction perpendicular to the machining progress direction. When the wire electrode 2 bends, the amount of bending becomes the largest at the central portion between the upper nozzle 81 and the lower nozzle 82, and the closer to the upper nozzle 81 or the lower nozzle 82, the smaller the amount of bending.

As described above, the shorter the distance between the nozzle closer to the workpiece 7 and the workpiece 7, the smaller the amount of deflection. In other words, the smaller the absolute value of the difference between the distance from the lower nozzle 82 and the distance from the upper nozzle 81 of the workpiece 7, the larger the amount of deflection. In the workpiece 7B shown in FIG. 10, the absolute value of the difference between the distance from the lower nozzle 82 and the distance from the upper nozzle 81 is R1, and the workpiece 7D has the distance from the lower nozzle 82 and the upper nozzle. The absolute value of the difference from 81 to the distance is R3. Further, in the workpiece 7C shown in FIG. 10, the absolute value of the difference between the distance from the lower nozzle 82 and the distance from the upper nozzle 81 is | R2a-R2b |, which is smaller than R1 and R3.

As described above, in the workpiece 7C processed at the central portion of the wire electrode 2, the bending amount of the wire electrode 2 is about the same on both the upper surface and the lower surface of the workpiece 7C, so that the straightness accuracy is high. On the other hand, in the workpieces 7B and 7D machined at the end of the wire electrode 2, the straightness accuracy is low because the amount of bending of the wire electrode 2 differs between the upper surface and the lower surface of the workpieces 7B and 7C.

Therefore, if the shape dimension compensator 35 can acquire the nozzle separation amount via the nozzle separation amount detector 49 or the setting input IF 20, the work piece 7 can be processed by performing machining control according to the nozzle separation amount. The straightness accuracy can be improved.

The shape dimension compensator 35 calculates the wire tension for improving the straightness accuracy of the workpiece 7 based on the first correspondence information indicating the correspondence between the nozzle separation amount and the wire tension. The shape dimension compensator 35 can reduce the amount of bending of the wire electrode 2 by increasing the wire tension, for example, and can improve the straightness accuracy.

Further, the shape dimension compensator 35 calculates a voltage correction value for improving the straightness accuracy of the workpiece 7 based on the second correspondence relationship information indicating the correspondence relationship between the nozzle separation amount and the voltage correction value. do. Since the shape dimension compensator 35 can increase the machining speed by lowering the machining voltage according to the voltage correction value, it is possible to reduce the machining amount at the place where the nozzle separation amount is large, and control the straightness accuracy and the machining dimensional accuracy. can do.

Next, the wire tension command according to the estimated plate thickness will be described. The shape dimension compensator 35 calculates the wire tension command based on the estimated plate thickness.

When the plate thickness of the workpiece 7 is thick, the processing speed becomes slow and the processing amount increases. Especially in the central portion of the wire electrode 2, the amount of processing increases due to the bending of the wire electrode 2. In this case, since the wire electric discharge machining apparatus 100 can reduce the bending of the wire electrode 2 by increasing the wire tension, the machining amount in the region where the bending amount of the wire electrode 2 is large can be reduced, and the straightening accuracy is improved. Can be made to.

FIG. 11 is a diagram for explaining the relationship between the wire tension and the amount of bending of the wire electrode. In FIG. 11, the wire electrode when the amount of deflection is large is shown as the wire electrode 2B, and the wire electrode when the amount of deflection is reduced by increasing the wire tension is shown as the wire electrode 2A.

As shown in FIG. 11, the wire electric discharge machine 100 can suppress the bending of the wire electrode 2 by increasing the tension of the wire electrode 2, and can improve the straightness accuracy of the workpiece 7 accordingly. When the wire electric discharge machining apparatus 100 increases the wire tension, the wire electric discharge machining apparatus 100 increases the wire tension only to such an extent that the probability that the wire electrode 2 is broken is smaller than a specific value. The shape dimension compensator 35 calculates the wire tension for improving the straightness accuracy of the workpiece 7 based on the third correspondence information indicating the correspondence between the estimated plate thickness and the wire tension.

Next, a processing procedure for wire electric discharge machining by the wire electric discharge machining apparatus 100 will be described. FIG. 12 is a flowchart showing a processing procedure of wire electric discharge machining by the wire electric discharge machining apparatus according to the embodiment.

When the wire electric discharge machine 100 starts the wire electric discharge machining (step S10), the NC control device 33 collects data (step S20). Specifically, the plate thickness estimator 48 receives the machining voltage, the electric discharge machining energy, and the machining speed. Further, the nozzle separation amount detector 49 detects the nozzle separation amount, and the setting input IF 20 receives the reference plate thickness.

The plate thickness estimator 48 estimates the plate thickness of the workpiece 7 based on the processing voltage, electric discharge machining energy, and processing speed (step S30). The plate thickness estimator 48 sends the estimated plate thickness to the shape dimension compensator 35 as a plate thickness estimated value.

The shape dimension compensator 35 calculates the wire tension command, the voltage correction value, and the pause time correction value based on the plate thickness estimated value, the nozzle separation amount, and the reference plate thickness (step S40). The wire electric discharge machining apparatus 100 controls the machining voltage, machining energy, and wire tension by using the wire tension command, the voltage correction value, and the pause time correction value (step S50). Specifically, the feedback controller 43 feedback-controls the machining mechanism 30 with a voltage value and a pause time corresponding to the voltage correction value and the pause time correction value, and the wire tension control device 31 controls the wire tension of the wire electrode 2. Control.

The shape dimension compensator 35 may estimate and store the machined groove width at the time of the first machining. In this case, the shape and dimension compensator 35 estimates the machined groove width based on the first machined condition and the dimensional curve information, which are the machined conditions used in the first machined. Further, the wire electric discharge machining apparatus 100 may store the estimated plate thickness value at the time of the first machining. The shape dimension compensator 35 associates the estimated machining groove width and plate thickness estimated value with the coordinate information indicating the machining position of the workpiece 7, and stores it as machining result information.

The shape and dimension compensator 35 uses, for example, the second machining condition and the offset, which are the machining conditions used in the second and subsequent machining, by using the correspondence between the machining groove width and the coordinate information included in the machining result information. Adjust at least one of the quantities. The offset amount is the amount of the machining position (position of the wire electrode 2 in the Y-axis direction) used in the second and subsequent machining toward the workpiece 7.

In the second and subsequent machining, the machining amount changes depending on the offset amount, making it difficult to estimate the plate thickness. However, the shape dimension compensator 35 stores the machining result information generated in the first machining. Machining control can be executed based on the machining result information even in the second and subsequent machining.

The shape dimension compensator 35 calculates a voltage correction value, a pause time correction value, and a wire tension command by using, for example, the correspondence between the plate thickness estimated value and the coordinate information included in the machining result information.

In this way, the wire electric discharge machining apparatus 100 calculates the voltage correction value, the pause time correction value, and the wire tension command using the shape dimension compensator 35, so that the first time in the machining where the plate thickness changes. It is possible to improve the machining dimensions and straightening accuracy regardless of the plate thickness region of the workpiece 7 from the machining of.

Further, the wire electric discharge machining apparatus 100 continuously controls the axis movement command for keeping the machining voltage at a specific value and the time when the machining voltage is started to be applied next, without changing the machining conditions. The machining shape and machining dimensions of the workpiece 7 can be controlled by control.

In the present embodiment, the case where the shape dimension compensator 35 calculates the voltage correction value, the pause time correction value, the wire tension, and the like has been described, but the learning device that performs machine learning has the voltage correction value, the pause time correction value, and the like. , Wire tension, etc. may be calculated. That is, the function that models the machining dimension and straightness accuracy may be derived experimentally or by a learning device. When derived by the learning device, the learning device calculates voltage correction values, pause time correction values, and wire tension commands so that the machining dimensions of multiple plate thickness regions approach the machining dimensions of a particular plate thickness region. ..

When derived experimentally, the creator of the wire discharge machining apparatus 100 creates a function that models the machining dimensions and straightness accuracy based on the dimensional information that is the machining dimension information included in the past machining results. Set to the compensator 35.

When the learning device derives, the learning device is based on the information acquired in the machining process (hereinafter referred to as process information) such as the estimated plate thickness, machining voltage, discharge machining energy, machining speed, and nozzle separation amount. Information such as voltage correction value, pause time correction value, and wire tension (hereinafter referred to as accuracy improvement information) that can improve the accuracy of the machine and the accuracy of the machined shape is calculated.

The learning device generates a trained model that derives accuracy improvement information that can improve the accuracy and straightness accuracy of the machined dimension from the process information. In other words, the learning device generates a trained model that is a function that models the correspondence between the process information and the accuracy improvement information that can improve the accuracy and straightness accuracy of the machined dimensions. The inference device uses the trained model to derive accuracy improvement information that can improve the accuracy and straightness accuracy of the machined dimension from the process information.

<Learning phase>
FIG. 13 is a block diagram showing a configuration example of the learning device according to the embodiment. The learning device 50 includes a data acquisition unit 51 and a model generation unit 52. The data acquisition unit 51 acquires the processing result (behavior) and the processing parameter (state) as learning data.

The processing result is the processing dimension and processing shape (straightness accuracy). The machining parameters are a combination of parameters that affect the machining shape, such as the plate thickness, the wire diameter of the wire electrode 2, the material of the workpiece 7, the machining voltage, the electric discharge machining energy, the nozzle separation amount, and the wire tension.

The model generation unit 52 learns the voltage correction value, the pause time correction value, and the wire tension command based on the learning data including the behavior which is the machining result and the state which is the machining parameter. That is, the model generation unit 52 generates a trained model 71 that infers a voltage correction value, a pause time correction value, and a wire tension command from the processing parameters of the wire electric discharge machining apparatus 100.

The model generation unit 52 can use known learning algorithms such as supervised learning, unsupervised learning, and reinforcement learning. As an example, a case where reinforcement learning is applied to the model generation unit 52 will be described. In reinforcement learning, an agent (behavior) in a certain environment observes the current state (environmental parameters) and decides the action to be taken. The environment changes dynamically depending on the behavior of the agent, and the agent is rewarded according to the change in the environment. The agent repeats this process and learns the action policy that gives the most reward through a series of actions. Q-learning, TD-learning, and the like are known as typical methods of reinforcement learning. For example, in the case of Q-learning, the general update formula of the action value function Q (s, a) is expressed by the following formula (1).

In the formula (1), s _t represents the state of the environment at time t, a _t represents the behavior in time t. By the action a _t, the state is changed to s _{t + 1.} r _{t + 1} represents the reward received by the change of the state, γ represents the discount rate, and α represents the learning coefficient. Note that γ is in the range of 0 <γ ≦ 1 and α is in the range of 0 <α ≦ 1. Processing results in a behavioral action a _t next, a state is processed parameter next state s _t, the model generation unit 52 learns the best action a _t in state s _t at time t.

In the update formula represented by the equation (1), if the action value Q of the action a having the highest Q value at time t + 1 is larger than the action value Q of the action a executed at time t, the action value Q is increased. However, in the opposite case, the action value Q is reduced. In other words, the action value function Q (s, a) is updated so that the action value Q of the action a at time t approaches the best action value at time t + 1. As a result, the best behavioral value in a certain environment is sequentially propagated to the behavioral value in the previous environment.

As described above, when the trained model 71 is generated by reinforcement learning, the model generation unit 52 includes a reward calculation unit 53 and a function update unit 54.

The reward calculation unit 53 calculates the reward based on the machining result and the machining parameter. The reward calculation unit 53 calculates the reward r based on the machining accuracy, that is, the accuracy of the machining dimensions and the accuracy of the machining shape. For example, in the case of improving the processing accuracy, the reward r is increased (for example, the reward of "1" is given), while in the case of the deterioration of the processing accuracy, the reward r is decreased (for example, the reward of "-1" is given). .).

The function update unit 54 updates the function for determining the voltage correction value, the pause time correction value, and the wire tension command according to the reward calculated by the reward calculation unit 53, and outputs the function to the trained model storage unit 70. For example, in the case of Q-learning, action value function Q (s _t, a _t) represented by the formula (1) the voltage correction value, downtime correction value, and used as a function for calculating the wire tension instruction.

The function update unit 54 repeatedly executes the above learning. Learned model storage unit 70, action value is updated by the function updating unit 54 function _{Q (s t, a t)} , i.e., storing the learned model 71.

Next, the processing procedure of the learning process by the learning device 50 will be described with reference to FIG. FIG. 14 is a flowchart showing a processing procedure of learning processing by the learning device according to the embodiment. The data acquisition unit 51 acquires the machining result and the machining parameter as learning data (step S110).

The model generation unit 52 calculates the reward based on the machining result and the machining parameter (step S120). Specifically, the reward calculation unit 53 of the model generation unit 52 acquires the processing result and the processing parameter, and determines whether to increase the reward (step S130) or decrease the reward based on the predetermined processing accuracy. (Step S140). The reward standard is whether the accuracy of the machined dimensions and the precision of the machined shape have improved or deteriorated. The model generation unit 52 determines that the reward is increased when the accuracy of the machining dimension and the accuracy of the machining shape are improved, and is determined to reduce the reward when the accuracy of the machining dimension and the accuracy of the machining shape are deteriorated.

The model generation unit 52 may determine that the reward is increased or the reward is decreased when either the accuracy of the machining dimension or the accuracy of the machining shape is improved and the other is deteriorated. Further, the model generation unit 52 does not have to increase or decrease the reward when either the accuracy of the machining dimension or the accuracy of the machining shape is improved and the other is deteriorated.

When the reward calculation unit 53 determines that the reward is to be increased, the reward calculation unit 53 increases the reward in step S130. On the other hand, when the reward calculation unit 53 determines that the reward is to be reduced, the reward calculation unit 53 reduces the reward in step S140.

Function update unit 54 based on the compensation calculated by compensation calculation unit 53 updates the action value learned model storage unit 70 is represented by the formula (1) for storing function Q (s _t, a _t) (Step S150).

Learning apparatus 50 repeatedly executes the steps up to this step S110 to S150, the generated action-value function Q (s _t, a _t) a, and stores the learned model storage unit 70 as the learned model 71.

The learning device 50 according to the present embodiment stores the trained model 71 in the trained model storage unit 70 provided outside the learning device 50, but the trained model storage unit 70 is stored in the learning device 50. It may be provided inside.

<Utilization phase>
FIG. 15 is a block diagram showing a configuration example of the inference device according to the embodiment. The inference device 60 includes a data acquisition unit 61 and an inference unit 62. The data acquisition unit 61 acquires machining parameters.

The inference unit 62 infers the processing information 79 by using the learned model 71 stored in the learned model storage unit 70. The machining information 79 is a voltage correction value, a pause time correction value, and a wire tension command. That is, the inference unit 62 infers the voltage correction value, the pause time correction value, and the wire tension command suitable for the processing parameters by inputting the processing parameters acquired by the data acquisition unit 61 into the trained model 71. Can be done.

In the present embodiment, the case where the inference device 60 uses the trained model 71 learned by the model generation unit 52 of the learning device 50 has been described, but the trained model 71 acquired from another learning device is used. May be good. In this case as well, the inference device 60 outputs a voltage correction value, a pause time correction value, and a wire tension command based on the learned model 71 acquired from another learning device.

Next, the processing procedure of the inference processing by the inference device 60 will be described with reference to FIG. FIG. 16 is a flowchart showing a processing procedure of inference processing by the inference device according to the embodiment. The data acquisition unit 61 acquires inference data, which is data for inferring a voltage correction value, a pause time correction value, and a wire tension command (step S210). Specifically, the data acquisition unit 61 acquires machining parameters.

The inference unit 62 inputs machining parameters into the trained model 71 stored in the trained model storage unit 70 (step S220), and obtains a voltage correction value, a pause time correction value, and a wire tension command. The inference unit 62 outputs the obtained data, that is, the voltage correction value, the pause time correction value, and the wire tension command to the wire electric discharge machine 100 (step S230).

The wire electric discharge machining apparatus 100 corrects the machining voltage and the pause time by using the voltage correction value and the pause time correction value output from the inference unit 62 (step S240), and the wire tension command output from the inference unit 62 is used to correct the wire. The tension of the electrode 2 is controlled. As a result, the wire electric discharge machining apparatus 100 can improve the accuracy of the machining dimensions and the precision of the machining shape of the workpiece 7.

In the present embodiment, the case where reinforcement learning is applied to the learning algorithm used by the inference unit 62 has been described, but the present invention is not limited to this. As for the learning algorithm, it is also possible to apply supervised learning, unsupervised learning, semi-supervised learning, or the like, in addition to reinforcement learning.

Further, as the learning algorithm used in the model generation unit 52, deep learning, which learns the extraction of the feature amount itself, can also be used, and other known methods such as neural networks, genetic programming, and functions can be used. Machine learning may be performed according to logical programming, support vector machines, and the like.

The learning device 50 and the inference device 60 may be connected to the wire electric discharge machine 100 via a network, and may be separate devices from the wire electric discharge machine 100. Further, at least one of the learning device 50 and the inference device 60 may be built in the wire electric discharge machining device 100. Further, the learning device 50 and the inference device 60 may exist on the cloud server.

Further, the model generation unit 52 may learn the voltage correction value, the pause time correction value, and the wire tension command by using the learning data acquired from the plurality of wire electric discharge machines. The model generation unit 52 may acquire learning data from a plurality of wire electric discharge machines used in the same area, or may be collected from a plurality of wire electric discharge machines operating independently in different areas. The voltage correction value, the pause time correction value, and the wire tension command may be learned by using the learning data. It is also possible to add or remove the wire electric discharge machine for collecting learning data from the target on the way. Further, the learning device 50 that has learned the voltage correction value, the pause time correction value, and the wire tension command for one wire electric discharge machine is applied to another wire electric discharge machine, and the other wire electric discharge machine is used. The voltage correction value, the pause time correction value, and the wire tension command may be relearned and updated.

Here, the hardware configuration of the NC control device 33 will be described. FIG. 17 is a diagram showing a hardware configuration example that realizes the NC control device according to the embodiment. The NC control device 33 can be realized by the processor 91, the memory 92, the output device 93, and the input device 94.

An example of the processor 91 is a CPU (Central Processing Unit, a central processing unit, a processing unit, an arithmetic unit, a microprocessor, a microcomputer, a DSP (Digital Signal Processor)) or a system LSI (Large Scale Integration). Examples of the memory 92 are RAM (Random Access Memory) and ROM (Read Only Memory).

The NC control device 33 is realized by the processor 91 reading and executing a computer-executable control program for executing the operation of the NC control device 33 stored in the memory 92. It can also be said that the control program for executing the operation of the NC control device 33 causes the computer to execute the procedure or method of the NC control device 33. The control program for executing the operation of the NC control device 33 includes a program for processing the workpiece 7 and a program for executing the operation of the shape dimension compensator 35.

The control program executed by the NC control device 33 has a modular configuration including a plate thickness estimator 48, a shape dimension compensator 35, and a nozzle separation amount detector 49, and these are loaded on the main memory. And these are generated on the main memory.

The input device 94 receives the reference plate thickness and the like and sends it to the processor 91. The memory 92 stores voltage correction value information 77, energy correction value information, first to third correspondence information, dimensional curve information, and the like. Further, the memory 92 is used as a temporary memory when the processor 91 executes various processes.

The output device 93 outputs the voltage correction value and the pause time correction value generated by the processor 91 to the processing power supply 32. Further, the output device 93 outputs the wire tension command generated by the processor 91 to the wire tension control device 31.

The control program may be a file in an installable or executable format, stored in a computer-readable storage medium, and provided as a computer program product. Further, the control program may be provided to the NC control device 33 via a network such as the Internet. It should be noted that some of the functions of the NC control device 33 may be realized by dedicated hardware such as a dedicated circuit, and some may be realized by software or firmware.

Since the feedback controller 43, the wire tension control device 31, the learning device 50, and the inference device 60 have the same hardware configuration as the wire electric discharge machining device 100, the description thereof will be omitted.

As described above, in the embodiment, the shape dimension compensator 35 reduces the difference in machining dimensions between the plate thickness regions based on the machining voltage, machining energy, machining speed, nozzle separation amount, and plate thickness estimation value. Moreover, the voltage correction value, the rest time correction value, and the wire tension command are calculated so that the straightness accuracy of the workpiece becomes high in the plate thickness region. Then, the machining mechanism 30 uses the voltage correction value, the pause time correction value, and the wire tension command to perform wire electric discharge machining of the workpiece 7 whose plate thickness changes during machining. As a result, the wire electric discharge machining apparatus 100 can improve the accuracy of the machining dimensions and the accuracy of the machining shape even for the workpiece 7 whose plate thickness changes during machining.

The configuration shown in the above embodiment is an example, and can be combined with another known technique, or a part of the configuration may be omitted or changed without departing from the gist. It is possible.

1 Wire electrode bobbin, 2,2A, 2B Wire electrode, 3 Tension load device, 4 Upper power supply, 5 Lower power supply, 6 Upper guide, 7,7B, 7C, 7D workpiece, 8 platen, 9 wires Traveling speed control motor, 10 wire electrode recovery box, 11XX axis drive motor, 11YY axis drive motor, 12 lower guide, 13 lower roller, 20 setting input IF, 21 first plate thickness region, 22 second plate thickness Region, 23 3rd plate thickness region, 24 4th plate thickness region, 30, 34 machining mechanism, 31 wire tension control device, 32 machining power supply, 33 NC control device, 35 shape dimension compensator, 41, 42, 63 , 64, 75, 76, 80 Calculator, 43 Feedback Controller, 45 Machining Voltage Detector, 46 Machining Energy Detector, 48 Plate Thickness Estimator, 49 Nozzle Separation Detector, 50 Learning Device, 51 Data Acquisition Unit, 52 Model generation unit, 53 Reward calculation unit, 54 Function update unit, 60 Inference device, 61 Data acquisition unit, 62 Inference unit, 70 Learned model storage unit, 71 Learned model, 77 Voltage correction value information, 79 Processing information, 81 upper nozzle, 82 lower nozzle, 85 voltage correction value calculation unit, 86 pause time correction value calculation unit, 91 processor, 92 memory, 93 output device, 94 input device, 100, 101 wire discharge processing device.

Claims (10)

A processing mechanism that performs wire electric discharge machining using voltage pulses from wire electrodes on workpieces that have multiple plate thickness regions with different plate thicknesses on the processing path.
A plate thickness estimator that estimates the plate thickness of the workpiece during wire electric discharge machining, and
Based on the machining voltage during machining, the machining energy during machining, the machining speed during machining, the separation distance which is the distance between the nozzle that supplies the machining liquid to the wire electrode and the workpiece, and the plate thickness. The processing voltage is corrected so that the difference in processing dimensions between the plate thickness regions is small and the straightness accuracy of the work piece in the length direction of the wire electrodes is high within each plate thickness region. A voltage correction value that is a value, a pause time correction value that is a correction value for the pause time of the voltage pulse, and a shape dimension compensator that calculates a wire tension command that is a tension command to the wire electrode.
Equipped with
The machining mechanism is controlled using the voltage correction value, the pause time correction value, and the wire tension command.
A wire electric discharge machine characterized by this. The shape dimension compensator is the processing of the workpiece when wire electric discharge machining is executed by a plurality of combinations of the machining voltage, electric discharge machining energy, the separation distance, and the wire tension of the wire electrode. Using the control model set based on the dimensions and the straightness accuracy, the voltage correction value, the pause time correction value, and the wire tension command are calculated.
The wire electric discharge machining apparatus according to claim 1. In the control model, at least one of the wire diameter of the wire electrode and the material of the workpiece is set.
The wire electric discharge machining apparatus according to claim 2. The shape and dimension compensator is
The voltage correction value and the pause so that the machining dimensions of the plurality of plate thickness regions approach the machining dimensions in a specific plate thickness region based on the dimensional information which is the machining dimension information included in the past machining results. Calculate the time correction value and the wire tension command,
The wire electric discharge machining apparatus according to any one of claims 1 to 3. The shape and dimension compensator estimates the machining groove width for the workpiece based on the first machining conditions and the dimensional information used in the first wire electric discharge machining for the workpiece, and the above-mentioned Based on the plate thickness estimated in the first wire electric discharge machining on the workpiece and the machined groove width, to the workpiece of the wire electrode used in the second and subsequent wire electric discharge machining. Adjust the offset amount, which is the amount of alignment of the wire, and the second machining condition.
The wire electric discharge machining apparatus according to claim 4. The specific plate thickness region is the thinnest plate thickness region among the plurality of plate thickness regions.
The wire electric discharge machining apparatus according to claim 4. The plate thickness of each of the plate thickness regions estimated when wire electric discharge machining is performed using a voltage pulse from a wire electrode on a workpiece having a plurality of plate thickness regions having different plate thicknesses on the processing path. Based on the machining voltage, machining energy, machining speed, and separation distance, which is the distance between the nozzle that supplies the machining liquid to the wire electrode and the workpiece, when machining each of the plate thickness regions. With the correction value of the machining voltage, the difference in machining dimensions between the plate thickness regions is small and the straightness accuracy of the work piece in the length direction of the wire electrode is high within each plate thickness region. A certain voltage correction value, a pause time correction value which is a correction value of the pause time of the voltage pulse, and a wire tension command which is a tension command to the wire electrode are calculated.
A shape and dimension compensator characterized by that. Including a machining step in which a wire electric discharge machine performs wire electric discharge machining using a voltage pulse from a wire electrode on a workpiece having a plurality of plate thickness regions having different plate thicknesses on a machining path.
The processing step is
An estimation step in which the wire electric discharge machine estimates the plate thickness of the work piece during wire electric discharge machining.
The separation distance, which is the distance between the nozzle and the workpiece to which the wire electric discharge machining apparatus supplies the machining voltage during machining, the machining energy during machining, the machining speed during machining, and the machining liquid to the wire electrode. And based on the plate thickness, the difference in machining dimensions between the plate thickness regions becomes small, and the straightness accuracy of the workpiece in the length direction of the wire electrode becomes high in each of the plate thickness regions. As described above, the calculation step of calculating the voltage correction value which is the correction value of the machining voltage, the pause time correction value which is the correction value of the pause time of the voltage pulse, and the wire tension command which is the tension command to the wire electrode.
Including
The wire electric discharge machine controls the wire electric discharge machining by using the voltage correction value, the pause time correction value, and the wire tension command.
A wire electric discharge machining method characterized by this. The machining parameters of a wire electric discharge machine that performs wire electric discharge machining using a voltage pulse from a wire electrode on a workpiece having a plurality of plate thickness regions having different plate thicknesses on the machining path, and the above-mentioned machining parameters. A data acquisition unit that acquires learning data including the processing results of the wire electric discharge machine,
Using the learning data, from the machining parameters of the wire electric discharge machine to the voltage correction value which is the correction value of the machining voltage, the pause time correction value which is the correction value of the pause time of the voltage pulse, and the wire electrode. A model generator that generates a trained model for inferring the wire tension command, which is the tension command of
Equipped with
The trained model is
Based on the machining voltage during machining, the machining energy during machining, the machining speed during machining, the separation distance which is the distance between the nozzle that supplies the machining liquid to the wire electrode and the workpiece, and the plate thickness. The voltage correction value is such that the difference in processing dimensions between the plate thickness regions is small and the straightness accuracy of the work piece in the length direction of the wire electrode is high within each plate thickness region. , The pause time correction value, and the wire tension command are inferred.
A learning device characterized by that. A data acquisition unit that acquires the machining parameters of a wire electric discharge machine that performs wire electric discharge machining using voltage pulses from wire electrodes on a workpiece having multiple plate thickness regions with different plate thicknesses on the machining path. ,
Using a trained model for inferring the machining result of the wire electric discharge machining device from the machining parameters, the voltage correction value, which is the correction value of the machining voltage, and the voltage pulse are obtained from the machining parameters acquired by the data acquisition unit. The pause time correction value, which is the correction value for the pause time, and the inference unit, which infers and outputs the wire tension command, which is the tension command to the wire electrode, and
Equipped with
The trained model is
Based on the machining voltage during machining, the machining energy during machining, the machining speed during machining, the separation distance which is the distance between the nozzle that supplies the machining liquid to the wire electrode and the workpiece, and the plate thickness. The voltage correction value is such that the difference in processing dimensions between the plate thickness regions is small and the straightness accuracy of the work piece in the length direction of the wire electrode is high within each plate thickness region. , The pause time correction value, and the wire tension command are inferred.
An inference device characterized by that.

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