JP2008100338A - Electrical discharge processing device and electric discharge processing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an electrical discharge processing device capable of realizing an electrical discharge processing without breaking a wire when a fixing hole exists on a processing path of a workpiece. <P>SOLUTION: This device comprises a processing condition storage part storing processing conditions including a control parameter at a workpiece shape variation portion corresponding to a kind of a shape formed on a workpiece and a processing section for executing the control parameter, an shape information acquisition part 15 on a processing path for acquiring the shape variation position and the kind of the shape on the processing path, extracting the processing section corresponding to a combination of the kind of the shape and a nozzle separation volume from the processing conditions of the processing condition storage part 13 per shape variation position on the processing path, and creating processing path information set on the processing path, a processing progression position acquisition part 17, and a processing condition decision part 18 for extracting the processing condition corresponding to the kind of the shape in the processing section from the processing condition storage part 13 and setting it as a new processing condition when the current processing progression position reaches the processing section in the processing path information. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electric discharge machining apparatus and an electric discharge machining method.

  In machining a workpiece in a conventional electric discharge machining apparatus, the wire may be disconnected depending on the distance from the nozzle that discharges the machining fluid to the workpiece. Therefore, a technique for preventing wire breakage during wire electric discharge machining has been proposed (see, for example, Patent Document 1).

  The electric discharge machining apparatus of Patent Document 1 includes a machining condition storage unit that stores machining conditions when a nozzle is in close contact with a workpiece, a liquid flow rate database that stores a relationship between a plate thickness, a nozzle height, and a liquid flow rate, A liquid flow rate determining means for determining a liquid flow rate in rough machining based on this relationship, and a controller for performing electric discharge machining based on the determined liquid flow rate are provided. When the nozzle height is input, the liquid flow rate corresponding to the plate thickness, the upper nozzle height, and the lower nozzle height is extracted from the liquid flow rate database and determined.

International Publication No. 02/034445 Pamphlet

  By the way, a work hole to be machined is formed with a stop hole having a narrow diameter and a deep shape, and this stop hole may exist on the processing path. When the wire passes through this stop hole, the flow of the machining fluid is disturbed, which causes the wire to vibrate and break the wire. With conventional electrical discharge machining equipment, machining can be controlled appropriately with the stop hole shape. Even if the machining is interrupted as a result of repeated disconnection or the machining progresses, there is a problem that the line at the time of the disconnection remains on the machining surface and affects the accuracy.

  Moreover, the determination of the processing conditions when processing the workpiece in the above-described conventional technology is performed when the workpiece is regarded as a flat plate, that is, on the assumption that there is no change in the thickness of the workpiece. Moreover, in the above conventional technique, the processing is performed on all processing paths under the conditions. Therefore, in the above conventional technology, since the machining fluid control is not performed for the disturbance of the machining fluid due to the change in the thickness shape of the workpiece, there is a special shape such as a stop hole or a large step on the machining path. It did not solve the problem of the occurrence of wire breakage.

  The present invention has been made in view of the above, and when performing a wire electric discharge machining process on a workpiece, if a stop hole exists on the machining path, the electric discharge machining process can be performed without disconnecting the wire. An object is to obtain an electric discharge machining apparatus and an electric discharge machining method.

  In order to achieve the above object, an electric discharge machining apparatus according to the present invention provides a wire for electric discharge machining of a workpiece to be machined under predetermined machining conditions and a machining portion between the wire and the workpiece from the extending direction of the wire. In an electric discharge machining apparatus comprising a nozzle for supplying a machining fluid toward a workpiece and numerical control means for processing the workpiece using the wire based on a numerical control program, the type of shape formed on the workpiece A machining condition storage means for storing machining conditions including a control parameter in a corresponding shape change portion of the workpiece and a processing section for executing the control parameter, a shape change position on the machining path, and a type of the shape For each shape change position on the processing path, the processing condition storage means obtains a processing section corresponding to a combination of a shape type and the nozzle separation amount. Machining path shape information acquisition means for creating machining path information extracted from machining conditions and set on the machining path, and machining progress position acquisition means for acquiring the current machining progress position in the workpiece during electric discharge machining processing And when the current machining progress position acquired by the machining progress position acquisition means reaches the processing section in the processing path information, the processing condition corresponding to the type of shape in the processing section is set as the processing condition. Machining condition setting means that is extracted from the storage means and is set as a new machining condition, and the numerical control means executes the electric discharge machining process based on the machining condition set by the machining condition setting means. Features.

  According to this invention, even if there is a sudden change in the machining shape of the workpiece on the machining path, the machining is performed under the machining conditions according to the combination of the shape type and the nozzle separation amount. There is an effect that it is possible to suppress the occurrence of disconnection and machining streaks due to the disturbance of the machining fluid due to the shape change.

  Exemplary embodiments of an electric discharge machining apparatus and an electric discharge machining method according to the present invention will be described below in detail with reference to the accompanying drawings. Note that the present invention is not limited to the embodiments.

  First, a description will be given of a stop hole to be subjected to special control in the wire electric discharge machining process according to the present invention. FIG. 1 is a perspective view schematically showing an example of a stop hole shape. The stop hole 111 is a hole formed in the workpiece 101, and is generally a hole having an aspect ratio, which is a ratio of a depth to a hole diameter, of 0.25 or more. For example, it is a stop hole having a hole diameter of 20 mm or less and a hole depth of 5 mm or more.

  FIG. 2 is a diagram schematically illustrating a state of the wire when the wire passes through the stop hole portion during the electric discharge machining process. In FIG. 2, it is assumed that the processing proceeds from the left side to the right side of the drawing. As shown in FIG. 2, the wire 31 is in a normal state with no slack at the positions R1, R3, and R5 where there is no change in the shape of the work 101, but the position of the entrance portion in the shape of the stop hole 111. In a portion where there is a sudden change in the shape of the workpiece 101, such as R2 or the position R4 of the exit portion, the wire 31 vibrates due to the influence of the disturbance of the flow of the machining fluid. Since the wire 31 is brought into contact with the workpiece due to the vibration and the current is concentrated on the contacted portion, the wire 31 is disconnected at the shape change portion as a result.

  There are at least four types of stop holes that cause wire cutting during such processing. FIGS. 3-1 to 3-4 are cross-sectional views showing types of stop holes in which the wire is cut. Here, the upper and lower sides are defined based on the state where the workpiece 101 is installed in the electric discharge machining apparatus when machining the workpiece 101. FIG. 3A is a counterbore stop hole in which a stop hole 111 is formed on the upper surface of the work 101, and FIG. 3B is a lower hole stop hole in which the stop hole 111 is formed on the lower surface of the work 101. Yes, FIG. 3C is a counterbore stop hole in which a stop hole 111 is formed at substantially the same position above and below the workpiece 101. FIG. 3-4 shows that the stop hole 111 is formed inside the workpiece 101. It is a hollow stop hole. If any one of these stop holes 111 exists on the machining path, the wire 31 is likely to be cut as described with reference to FIG. 2, and the phenomenon that the wire contacts the workpiece is repeated even when the wire 31 is not cut. Streaks remain in the workpiece.

  Incidentally, the cutting of the wire 31 is influenced not only by the presence of the stop hole 111 but also by the distance between the workpiece 101 and the nozzle for supplying the machining liquid (hereinafter referred to as the nozzle separation amount). FIG. 4 is a schematic diagram for explaining the definition of the nozzle separation amount. As shown in this figure, an upper nozzle 41 for supplying a machining fluid to the wire 31 is disposed at a position above the workpiece 101 of the wire 31 for cutting the workpiece 101, and is located below the workpiece 101 of the wire 31. A lower nozzle 42 for supplying the processing liquid to the wire 31 is disposed at the position. Here, the distance between the intersection of the upper surface of the workpiece 101 and the wire 31 and the machining liquid discharge surface of the upper nozzle 41 is the upper nozzle separation amount, and the intersection of the lower surface of the workpiece 101 and the wire 31 and the machining of the lower nozzle 42 are performed. The distance from the liquid discharge surface is the lower nozzle separation amount.

  FIG. 5 is a diagram illustrating the relationship between the nozzle separation amount and the hydraulic pressure. In this figure, the horizontal axis indicates the nozzle separation (mm), and the vertical axis indicates the hydraulic pressure (unit Pa). As shown in this figure, as the nozzle separation amount increases, that is, as the nozzles 41 and 42 move away from the intersection between the surface of the workpiece 101 and the wire 31, the liquid pressure decreases and the machining liquid reaching the machining site decreases and sludge becomes smaller. It turns out that it is not discharged enough.

  For example, as shown in FIGS. 3A to 3C, when the stop hole 111 appears on the surface of the workpiece 101, the nozzle separation amount differs between the stop hole 111 and other portions. In other words, in the portion where the stop hole 111 exists, the fluid pressure of the machining fluid is weakened and sludge cannot be sufficiently discharged. That is, the two causes of the disturbance of the liquid in the stop hole and the weakening of the liquid due to the separation of the nozzle are related to each other, and the wire breakage occurs.

  FIG. 6 is a diagram illustrating an example of a positional relationship between the workpiece and the upper and lower nozzles before and after the machining shape change position. In this figure, the case where the stop holes 111 are formed on the upper and lower surfaces of the workpiece 101 is shown. The upper nozzle separation amount at the position R11 before the machining shape change position is s0, and the lower nozzle separation amount is t0.

  On the other hand, when passing the machining shape change position, the wire 31 is in the position of the stop hole, the upper nozzle separation amount at the position R12 after the machining shape change position is s1 larger than s0, and the lower nozzle separation amount is from t0. Is also large t1.

  Thus, before and after the machining shape change position, the upper nozzle separation amount / lower nozzle separation amount changes. As described above, when the upper nozzle separation amount / lower nozzle separation amount increases, the fluid pressure of the machining fluid is weakened. Therefore, in this embodiment, the upper nozzle separation is prevented so that the fluid pressure of the machining fluid is not weakened. The flow rate of the machining fluid is changed according to the rate of change in the amount / lower nozzle separation amount.

  Specifically, control is performed so that the flow rate of the machining fluid is increased when the nozzle separation amount increases. Further, since it is difficult to control the machining at the machining shape change position, the machining energy amount and the machining area speed are reduced as compared with the machining conditions at the normal position.

  In other words, in this embodiment, information on the stop hole existing on the processing path is acquired in advance, and in the stop hole portion, the processing condition including the liquid amount of the processing liquid is set according to the nozzle separation amount and the type of the stop hole. It is characterized by being controlled.

  Further, in this embodiment, the processing conditions are not changed suddenly at the stop hole portion, but the processing conditions are changed between the region including the portion where the step hole is present and the region before and after the region.

  Specifically, in the part of the processing path before the step part of the stop hole, the processing condition is gradually changed from the current processing condition to the processing condition of the step part, so that the wire break does not occur in the step part. Processing is performed, and the processing condition is gradually returned from the processing condition in which the wire breakage does not occur to the original processing condition in the portion after the step portion of the stop hole of the processing path. The length of the processing section is determined by the hole diameter of the machining liquid discharge port, the feature of the shape, and the error between the shape position information and the actual position. According to the experiment, when the hole diameter of the machining fluid discharge port is 4 mm, the machining conditions are changed linearly within a processing section length of about 4 mm with a stop hole shape with an aspect ratio of 2.5 and a positional error of ± 0.5 mm. Further, it is known that when the wire is returned, wire breakage does not occur and stable processing is performed.

  By doing in this way, it becomes possible to reduce the machining streak generated in the machining location due to a sudden change in machining conditions. Below, the electrical discharge machining apparatus and electrical discharge machining method which implement | achieve such a machining process are demonstrated.

  FIG. 7 is a block diagram schematically showing the configuration of the electric discharge machining apparatus according to the present invention. The electric discharge machining apparatus 10 includes a three-dimensional shape information storage unit 11, an NC program storage unit 12, a machining condition storage unit 13, a nozzle position acquisition unit 14, a machining path shape information acquisition unit 15, a machining path information storage unit 16, a machining It consists of a progress position acquisition unit 17, a processing condition determination unit 18, a processing condition change unit 19, an output / display unit 20, a numerical control unit 21, and a control unit 22 that controls these processing units.

  The three-dimensional shape information storage unit 11 stores three-dimensional shape information of a workpiece that is a machining target. The three-dimensional shape information is configured by a set of data such as coordinates and thicknesses at the coordinate positions of the shape of a workpiece to be processed. As this three-dimensional shape information, data created by CAD (Computer-Aided Design) can be used.

  Further, the three-dimensional shape information includes a shape name indicating what the shape (hole, step, etc.) of the characteristic portion of each shape in the data is. The technology for identifying and setting the shape of each shape feature in this data is publicly known (see, for example, Japanese Patent Application Laid-Open No. 2006-142396 and International Publication No. 01/081035 pamphlet). Omitted. The three-dimensional shape data is created or input by the user of the electric discharge machining apparatus 10. In this embodiment, the feature portion of the shape is automatically extracted from the three-dimensional shape information. However, it is not always necessary to automatically extract the feature portion. For example, a database of machining positions and shape features is input from the outside. Or may be created and edited by an operator.

  The NC program storage unit 12 stores an NC program for machining a workpiece. The NC program includes a machining path for machining a workpiece and machining conditions at a predetermined position in the machining accounting.

  The machining condition storage unit 13 stores machining conditions including control parameters in a shape change transition section including a step on the machining path of the stop hole.

  FIG. 8 is a diagram illustrating an example of processing conditions. This processing condition includes processing state information including information on the nozzle separation amount and stop hole, and control parameters for the processing state information. The processing state information includes an upper nozzle separation amount that is a distance between the ejection surface of the upper nozzle and the upper surface of the workpiece, and a lower nozzle separation amount that is a distance between the ejection surface of the lower nozzle and the lower surface of the workpiece. Further, the stop hole information includes the type of the stop hole shown in FIGS. 3-1 to 3-4, the hole diameter and the hole depth for the stop hole.

  The control parameter is a control parameter (inlet) that is a control parameter when machining from the outside of the stop hole to the stop hole, a control parameter (outlet) that is a control parameter when machining from the stop hole to the outside of the stop hole, Consists of. In these control parameters, the machining fluid flow rate, machining fluid control including the balance of machining fluid flow discharged from the upper nozzle and lower nozzle, machining energy amount, maximum machining area speed during machining, and processing section length It consists of. In this example, the control parameter is divided between the inlet and the outlet. However, as long as the wire breakage does not occur at the inlet and the outlet, the control parameters may be set as one control parameter without distinguishing between the two.

  When the machining fluid flow changes abruptly, such as at the entrance and exit of a stop hole, the conventional function to determine the machining feed rate by feeding back the state between the poles does not operate correctly, and the machining feed rate becomes abnormal. As a result, the machining may become unstable. Here, the machining area speed is represented by the product of the workpiece thickness and the machining speed. The maximum machining area speed is a machining area speed set in order to suppress an increase in the abnormal machining feed rate as described above. This speed is set to a machining area speed at which the machining speed is sufficiently slow even with the plate thickness at the deepest part of the stop hole. In actual machining, processing is executed at a machining area speed equal to or lower than the maximum machining area speed indicated in the machining conditions.

  The processing section length is performed after the main process, which is a process performed in the shape change transition section including a portion where the shape changes (stepped part), a pre-process which is a process performed before the main process, and the main process. It is further subdivided into post-processing that is processing. The processing section length of this processing indicates the length when the midpoint is brought to the machining shape change position.

  The machining condition storage unit 13 is set with electrical conditions such as the amount of machining energy reduced compared to the machining conditions at the normal position and machine conditions such as the maximum machining area so that the wire is not disconnected at the machining shape change position. ing. In addition, the flow rate balance is changed in consideration of the change in the upper nozzle separation amount / lower nozzle separation amount due to the presence of the stop hole. The machining condition storage unit 13 corresponds to the machining condition storage means in the claims.

  The nozzle position acquisition unit 14 acquires the nozzle position including the upper nozzle separation amount and the lower nozzle separation amount during the electric discharge machining process. As the nozzle position, a value input by a user of the electric discharge machining apparatus 10 may be used, or the nozzle position may be obtained by calculation using the specification of the electric discharge machining apparatus 10 and the three-dimensional shape information of the workpiece. Good. The nozzle position acquisition unit 14 corresponds to nozzle position acquisition means in the claims.

  The machining path shape information acquisition unit 15 acquires a plan view when wire EDM of the workpiece is performed from the three-dimensional shape information of the workpiece in the three-dimensional shape information storage unit 11, and the machining path of the NC program is included in this plan view. And processing path information in which a processing section in which processing control is performed according to the processing shape change position is set. If there is a stop hole on the processing path of the NC program, the processing path information indicates a processing section length corresponding to the type of the stop hole and the nozzle position acquired by the nozzle position acquisition unit 14. A processing section length is acquired from among the 13 processing conditions, and a processing section for performing processing control is set on the processing path. This on-machining path shape information acquisition unit 15 corresponds to on-machining path shape information acquisition means in the claims.

  9 to 10 are diagrams showing specific examples of shape information acquisition processing by the shape information acquisition unit on the processing path, and FIG. 9 is a diagram showing a state in which the processing path is superimposed on the top view of the workpiece. In the drawings, 111A and 111B indicate counterbore stop holes having a predetermined diameter. FIG. 10 is a diagram illustrating an example of processing section setting processing. The machining path shape information acquisition unit 15 obtains a top view from the 3D shape information of the workpiece 101 in the 3D shape information storage unit 11. Further, the machining path 51 of the NC program is acquired from the NC program storage unit 12, and the machining path 51 is superimposed on the top view of the workpiece 101. This is shown in FIG. At this time, the processing path shape information acquisition unit 15 determines that the stop holes 111A and 111B on the processing path are both spotted from the shape name of the feature part included in the three-dimensional shape information, and the hole diameter and hole. Acquires the hole information including depth.

  Further, the processing path shape information acquisition unit 15 performs processing corresponding to the nozzle position and the stop hole information acquired by the nozzle position acquisition unit 14 for the portion where the upper stop holes 111A and 111B exist on the processing path 51. The section length is acquired from the machining condition storage unit 13. Here, the length of each processing section is assumed to be preprocessing L, main processing M, and postprocessing N (L, M, N> 0). The L section is a section in which processing conditions in the M section are set as target values and the machining conditions are gradually changed. In the N section, the machining conditions changed in the M section are gradually restored.

  The machining path shape information acquisition unit 15 matches the midpoint of the length M of this process (a point corresponding to M / 2) with the intersection R between the step boundary line portion of the stop hole 111 </ b> A and the machining path 51. A range of M / 2 is set as a shape change transition section in each direction on the machining path 51 with the intersection R as the center.

  Furthermore, the range of the length L of the preprocessing from the end on the front side in the direction of travel of the shape change transition section is set as a shape change transition section preprocess section (hereinafter referred to as a preprocess section), and the direction of travel of the shape change transition section A range from the end on the side to the post-processing length N is set as a shape change transition section post-processing section (hereinafter referred to as a post-processing section). This is shown in FIG.

  Then, the preprocessing section, the shape change transition section, and the postprocessing section are registered on the machining path 51. Similar processing is performed on other portions that intersect with the shape change positions of the stop holes 111A and 111B on the processing path 51, and processing path information is created. Taking the amount of machining fluid at the inlet of number 1 in FIG. 8 as an example, if the normal amount of fluid is 40, the amount of fluid in the example of number 1 is 20, so 2 mm before and 3 mm before the shape boundary. The liquid volume is decreased by 2 every 0.1 mm until the 2 mm section is controlled by the liquid volume 20 and the liquid volume is increased by 2 every 0.1 mm from 2 mm to 3 mm after the shape boundary. .

  The machining path information storage unit 16 stores the machining path information acquired by the machining path shape information acquisition unit 15. Further, the machining progress position acquisition unit 17 acquires a machining progress position that indicates at which position on the workpiece the wire is actually present during wire electric discharge machining. The processing progress position acquisition unit 17 corresponds to processing progress position acquisition means in the claims.

  The machining condition determination unit 18 superimposes the current machining progress position acquired by the machining progress position acquisition unit 17 on the machining path, determines whether or not the current machining progress position is in the shape change transition section, and performs the current machining. When the advancing position is in the shape change transition section, control parameters corresponding to the nozzle position and stop hole information acquired by the nozzle position acquisition unit 14 are acquired from the processing condition storage unit 13, and the processing conditions are determined.

  When the current machining progress position is within the preprocessing section, the machining conditions were gradually changed so that the machining condition at the normal position becomes the machining condition in the shape change transition section at the end of the preprocessing section. Determine the processing conditions.

  In addition, when the current processing progress position is a post-processing section, the processing conditions are gradually changed so that the processing conditions in the shape change transition section become the processing conditions at the normal position at the end of the post-processing section. Decide on the condition.

  The machining condition changing unit 19 changes the machining conditions performed based on the NC program to the machining conditions determined by the machining condition determining unit 18. These machining condition determining unit 18 and machining condition changing unit 19 correspond to the machining condition setting means in the claims.

  The output / display unit 20 visually displays three-dimensional shape information, NC programs, condition change areas, and the like. Generally, it is configured by a display device such as a liquid crystal display device.

  The numerical control unit 21 controls the wire feed speed, the flow rate of the machining fluid, the discharge energy, etc. so as to machine the workpiece based on the NC program having the machining conditions changed by the machining condition changing unit 19. Wire electrical discharge machining is performed. The numerical control unit 21 corresponds to numerical control means in the claims.

  Here, a processing procedure of electric discharge machining in the electric discharge machining apparatus 10 will be described. First, the shape change extraction process on the machining path will be described with reference to the flowchart of FIG.

  First, the on-machining path shape information acquisition unit 15 acquires the three-dimensional shape information of the workpiece to be machined from the three-dimensional shape information storage unit 11 and the machining path of the NC program for machining the workpiece from the NC program storage unit 12. Obtain (step S11). Next, the machining path shape information acquisition unit 15 obtains a drawing viewed from an angle at which the wire passage path becomes clear from the three-dimensional shape information of the workpiece, that is, a drawing (an upper surface view) of the angle viewed from the longitudinal direction of the wire. Create (step S12). Thereafter, the processing path shape information acquisition unit 15 superimposes the processing path on the top view of the workpiece (step S13). This state is shown in FIG.

  Next, the machining path shape information acquisition unit 15 acquires the shape change position of the workpiece on the machining path and its stop hole information (step S14). The shape is already registered in the three-dimensional shape information, and is extracted from there.

  Moreover, the shape information acquisition part 15 on a process path | route acquires the nozzle position acquired by the nozzle position acquisition part 14 (step S15). Thereafter, for each shape change position, the processing section length corresponding to the shape and the nozzle position is acquired from the processing condition storage unit 13, and the shape change transition section, the preprocessing section, and the postprocessing section are set on the processing path ( Step S16). The set contents are stored as machining path information in the machining path information storage unit 16 (step S17), and the shape change extraction process is completed.

  Next, the electric discharge machining process will be described with reference to the flowcharts of FIGS. First, the numerical control unit 21 executes an actual electric discharge machining process based on a predetermined machining condition at a normal position defined in the NC program stored in the NC program storage unit 12 and stores machining path information. The actual machining progress position is traced on the machining path in the machining path information stored in the unit 16 (step S31). Next, the numerical controller 21 determines whether or not the machining process is finished (step S32). If the machining process is not completed (No in step S32), the machining progress position acquisition unit 17 determines whether or not the current machining progress position has reached the preprocessing section (step S33). If the preprocessing section has not been reached (No in step S33), the process returns to step S31. When the preprocessing section is reached (Yes in step S33), shape change transition section preprocessing is executed (step S34).

  FIG. 13 is a flowchart showing the procedure of the shape change transition section pre-processing. Here, when the machining progress position reaches the pre-processing section, the machining condition determination unit 18 stores the machining conditions corresponding to the nozzle position and the stop hole information recorded at the current machining progress position of the machining path information. Extracted from the unit 13 (step S101). Thereafter, the machining conditions are changed so as to be the extracted machining conditions at the last position in the preprocessing section (step S102), and the electric discharge machining process is executed under the changed machining conditions (step S103). In other words, the processing conditions at the normal position at the entrance of the preprocessing section are the processing conditions stored in the processing condition storage unit 13 in which the processing conditions are suppressed at the exit of the preprocessing section. The machining conditions are gradually changed as the process proceeds.

  Thereafter, the machining progress position acquisition unit 17 determines whether or not the current machining progress position has reached the shape change transition section (step S104). If the shape change transition section has not been reached (No in step S104), the process returns to step S102 and the above-described processing is repeated. If the shape change transition section has been reached (Yes in step S104), the shape change transition section pre-processing ends, and the process returns to the flowchart of FIG.

  Returning to FIG. 12 again, when the current machining progress position reaches the shape change transition section, the machining condition determination unit 18 corresponds to the nozzle information and the stop hole information recorded at the current machining progress position of the machining path information. The machining conditions are extracted from the machining condition storage unit 13 (step S35), and the electric discharge machining process is executed under the extracted machining conditions (step S36). In the electric discharge machining process under these machining conditions, since the machining conditions such as the electrical condition and the machine condition are suppressed as compared with the electric discharge machining process at the normal position, the wire breakage can be prevented.

  Thereafter, the machining progress position acquisition unit 17 determines whether or not the current machining progress position has reached the post-processing section (step S37). If the post-processing section has not been reached (No in step S37), the process returns to step S36, and the electric discharge machining process is performed in the shape change transition section. Further, when the current machining progress position has reached the post-processing section (Yes in step S37), the shape change transition section post-processing is executed (step S38).

  FIG. 14 is a flowchart illustrating a procedure of post-processing of the shape change transition section. Here, when the processing progress position reaches the post-processing section, the processing condition determination unit 18 sets the processing conditions corresponding to the nozzle position and the stop hole information recorded at the current processing progress position of the processing path information. Extracted from the storage unit 13 (step S121). Thereafter, the machining conditions are changed (step S122) so that the predetermined machining conditions at the normal position (the machining conditions in step S31) are reached at the last position in the post-processing section, and the electric discharge machining process is performed under the changed machining conditions. Execute (step S123). That is, the processing conditions stored in the processing condition storage unit 13 in which the processing conditions are suppressed at the entrance of the post-processing section, but the post-processing section is set so that the processing condition at the normal position is set at the exit of the post-processing section. The machining conditions are gradually changed as the process proceeds.

  Thereafter, the machining progress position acquisition unit 17 determines whether or not the current machining progress position has reached outside the post-processing section (step S124). If the position has not reached the post-processing section (No in step S124), the process returns to step S122 and the above-described processing is repeated. In addition, when the position has reached the outside of the post-processing section (Yes in step S124), the post-process for the shape change transition section is finished, the process returns to the flowchart of FIG. 12, and the electric discharge machining process is finished.

  Further, returning to FIG. 12 again, when the machining process is finished in step S32 (Yes in step S32), the electric discharge machining process is finished.

  In the above description, the machining condition determination by the machining condition determination unit 18 is stored in the machining condition storage unit 13 based on the nozzle position and stop hole shape information acquired by the nozzle position acquisition unit 14. The corresponding machining conditions are extracted from the machining conditions, but the machining conditions stored in the machining condition storage unit 13 are displayed on the output / display unit 20, and the user can specify the nozzle position and the stop hole in the machining conditions. You may comprise so that the edit means which inputs and selects a shape may be provided.

  According to this embodiment, even when a stop hole exists on the processing path, the processing conditions are reduced in the shape change transition section in the vicinity of the processing shape change position of the stop hole and the processing conditions are reduced as compared with the processing processing at the normal position. As a result, the wire breakage in the vicinity of the machining shape change position can be prevented.

  In addition, the pre-processing section and post-processing section that gently change the change in the machining condition between the normal position and the shape change transition section are provided before and after the shape change transition section. There is also an effect that generation of machining streaks can be suppressed.

  Further, in the above-described embodiment, the case where a stop hole exists on the machining path has been described as an example, but the same applies to a shape change on the workpiece that changes the flow of the machining liquid. It is possible to control the processing conditions.

  As described above, the electric discharge machining apparatus according to the present invention is useful for electric discharge machining of a workpiece having a stop hole on the machining path.

It is a perspective view which shows typically an example of a stop hole shape. It is a figure which shows typically the state of the wire at the time of a wire passing a stop hole part at the time of an electrical discharge machining process. It is sectional drawing which shows the kind of stop hole in which the cutting | disconnection of a wire produces. It is sectional drawing which shows the kind of stop hole in which the cutting | disconnection of a wire produces. It is sectional drawing which shows the kind of stop hole in which the cutting | disconnection of a wire produces. It is sectional drawing which shows the kind of stop hole in which the cutting | disconnection of a wire produces. It is a schematic diagram for demonstrating the definition of nozzle separation amount. It is a figure which shows the relationship between nozzle separation amount and a hydraulic pressure. It is a figure which shows an example of the positional relationship of the workpiece | work and an up-and-down nozzle before and behind a process shape change position. It is a block diagram which shows typically the structure of the electric discharge machining apparatus by this invention. It is a figure which shows an example of processing conditions. It is a figure which shows the state which piled up the process path | route on the upper side figure of the workpiece | work. It is a figure which shows an example of the setting process of a process area. It is a flowchart which shows an example of the extraction process of the shape change on a process path | route. It is a flowchart which shows an example of the procedure of an electrical discharge machining process. It is a flowchart which shows the procedure of a shape change transition area pre-process. It is a flowchart which shows the procedure of a shape change transition area post-process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Electrical discharge machining apparatus 11 Three-dimensional shape information storage part 12 NC program storage part 13 Processing condition storage part 14 Nozzle position acquisition part 15 Machining path shape information acquisition part 16 Machining path information storage part 17 Machining progress position acquisition part 18 Machining condition determination Unit 19 Machining condition change unit 20 Output / display unit 21 Numerical control unit 22 Control unit 31 Wire 41 Upper nozzle 42 Lower nozzle 101 Workpiece 111, 111A, 111B Stop hole

Claims (11)

A wire for electric discharge machining a workpiece to be machined under predetermined machining conditions;
A nozzle for supplying a machining fluid from the extending direction of the wire toward a machining portion of the wire with the workpiece;
Numerical control means for processing the workpiece using the wire based on a numerical control program;
In an electric discharge machining apparatus comprising:
A machining condition storage means for storing a machining parameter including a control parameter in a shape change portion of the workpiece corresponding to a type of shape formed on the workpiece, and a processing section for executing the control parameter;
The shape change position on the machining path and the type of the shape are acquired, and for each shape change position on the machining path, a processing section corresponding to a combination of the shape type and the nozzle separation amount is stored in the machining condition storage unit. Machining path shape information acquisition means for creating machining path information extracted from the machining conditions and set on the machining path;
Machining progress position acquisition means for acquiring a current machining progress position in the workpiece during electric discharge machining;
When the current machining progress position acquired by the machining progress position acquisition unit reaches a processing section in the processing path information, a processing condition corresponding to the shape type in the processing section is stored in the processing condition storage unit. Machining condition setting means that is extracted from and set as new machining conditions;
With
The electrical discharge machining apparatus, wherein the numerical control means executes an electrical discharge machining process based on the machining conditions set by the machining condition setting means. Nozzle position obtaining means for obtaining the nozzle separation amount;
The machining condition storage means is a shape change portion of the workpiece corresponding to a combination of a type of shape formed on the workpiece and a nozzle separation amount which is a distance between the surface of the workpiece and a machining liquid discharge surface of the nozzle. Storing processing conditions including a control parameter and a processing section for executing the control parameter;
The shape information acquisition means on the processing path superimposes the processing path of the numerical control program on the three-dimensional shape information having the three-dimensional shape of the workpiece, and determines the shape change position on the processing path and the type of the shape. The processing section corresponding to the combination of the shape type and the nozzle separation amount is extracted from the processing conditions of the processing condition storage means and set on the processing path for each shape change position on the processing path. Create machining path information,
The machining condition setting means, when the current machining progress position acquired by the machining progress position acquisition means reaches the processing section in the processing path information, the type of shape in the processing section and the nozzle separation The electric discharge machining apparatus according to claim 1, wherein a machining condition corresponding to a combination with a quantity is extracted from the machining condition storage means and set as a new machining condition.   The shape information acquisition means on the machining path superimposes the machining path of the numerical control program on the three-dimensional shape information having the three-dimensional shape of the workpiece, thereby determining the shape change position on the machining path and the type of the shape. The electric discharge machining apparatus according to claim 1, wherein the electric discharge machining apparatus is obtained. The processing section of the processing condition includes a shape change transition section that performs processing with the control parameter, and a preprocessing section and a postprocessing section that are provided before and after the shape change transition section.
The processing condition setting means includes
When the current processing progress position is within the preprocessing section, the end of the preprocessing section is the end point of the processing condition storage means corresponding to the combination of the shape type on the processing path and the nozzle separation amount. Gradually change the processing conditions so that it becomes the processing conditions,
If the current machining progress position is within the shape change transition section, set the machining conditions corresponding to the combination of the shape type on the machining path and the nozzle separation amount,
When the current processing progress position is within a post-processing section, the processing conditions are gradually changed at the end point of the post-processing section so as to satisfy the processing conditions specified in the numerical control program. The electric discharge machining apparatus according to any one of claims 1 to 3.   The control parameter of the processing condition includes a processing fluid amount from the nozzle, a processing energy amount, and a maximum processing area for each combination of a shape type on the processing path and a nozzle separation amount. The electric discharge machining apparatus according to any one of 1 to 4.   The control parameters for the machining conditions include an entrance control parameter for performing processing from the normal position toward the machining shape change position, and an exit control parameter for performing processing from the machining shape change position to the normal position. The electric discharge machining apparatus according to claim 1, wherein: The wire is arranged vertically with respect to the workpiece;
The nozzle is provided above and below the workpiece,
The control parameter of the processing condition includes processing liquid control information including a liquid amount of the processing liquid and a flow rate balance from the upper and lower nozzles for each combination of a shape type on the processing path and a nozzle separation amount. The electric discharge machining apparatus according to claim 5, wherein the electric discharge machining apparatus is characterized.   The shape type formed on the workpiece under the processing conditions is further classified according to a shape type that causes a shape change and a size of the shape. The electric discharge machining apparatus according to 1.   The electric discharge machining apparatus according to claim 8, wherein the type of shape formed on the workpiece under the machining conditions is a stop hole. Display means for displaying the machining conditions stored in the machining condition storage means;
Editing means for editing the machining conditions displayed on the display means;
Further comprising
The electrical discharge machining apparatus according to claim 1, wherein the numerical control unit performs an electrical discharge machining process based on the edited machining condition selected and edited by the editing unit. A wire for electric discharge machining a workpiece to be machined under predetermined electrical conditions;
A nozzle for supplying a machining fluid from the extending direction of the wire toward a machining portion of the wire with the workpiece;
Control parameters in the shape change portion of the workpiece corresponding to the combination of the type of shape formed on the workpiece and the nozzle separation amount which is the distance between the surface of the workpiece and the machining liquid discharge surface of the nozzle, and the control thereof Machining condition storage means for storing machining conditions including a processing section for executing parameters;
Numerical control means for processing the workpiece using the wire based on a numerical control program;
An electrical discharge machining method for an electrical discharge machining apparatus comprising:
Obtaining the nozzle separation amount;
Superimposing the machining path of the numerical control program on the three-dimensional shape information indicating the three-dimensional shape of the workpiece, and obtaining the shape change position and the shape type on the machining path;
Extracting a processing section corresponding to a combination of the type of shape on the machining path and the nozzle separation amount from the machining condition storage unit and setting it on the machining path, and creating machining path information;
Obtaining a current machining progress position in the workpiece during electric discharge machining;
When the acquired current processing progress position reaches a processing section in the processing path information, the processing conditions corresponding to the combination of the shape type on the processing path and the nozzle separation amount are stored in the processing conditions. Extracting from the means and setting as new processing conditions;
The numerical control means performing an electric discharge machining process based on the new machining conditions;
An electrical discharge machining method comprising:

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