JP7280098B2 - Wire electric discharge machine and wire electric discharge machining method - Google Patents

Description

The present invention provides a wire electric discharge machine and a wire electric discharge machine for re-machining a machined surface by relatively moving a wire electrode along the machined surface of a workpiece and applying a voltage between the machined surface and the wire electrode to cause electric discharge. It relates to an electrical discharge machining method.

A wire electric discharge machine processes a workpiece by applying a voltage between the workpiece and the wire electrode to cause electrical discharge while moving the workpiece and the wire electrode relative to each other according to a machining program. A machining program indicates a machining path of a wire electrode for an object to be machined, and is generated for each object to be machined.

For example, in Patent Document 1, first machining (rough machining) is performed using a machining program generated in advance, and second machining is performed using a machining program in which the machining path is shifted by a predetermined distance toward the workpiece. A technique for (finishing, reworking) is disclosed.

JP-A-2000-158235

Since the discharge energy during rough machining is strong, the workpiece may be distorted. If the finish machining of a distorted workpiece is performed using a machining program generated in advance, there is a risk that the surface roughness will deteriorate. Moreover, the work of generating the machining program takes time.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a wire electric discharge machine and a wire electric discharge machining method that do not require a machining program when remachining an object to be machined.

A first aspect of the present invention is
Wire electric discharge machining for re-machining the machined surface by applying a voltage between the gap formed by the machined surface and the wire electrode while relatively moving the wire electrode along the machined surface of the object to be machined to cause electric discharge. machine and
a discharge state detection unit that detects a discharge state value indicating a state of discharge occurring between the electrodes;
a drive control unit that determines a traveling direction of the wire electrode with respect to the workpiece based on the discharge state value and moves the wire electrode along the traveling direction at a constant speed with respect to the workpiece;
Prepare.

A second aspect of the present invention is
A wire electric discharge machine is used to relatively move a wire electrode along a machining surface of an object to be machined, and apply a voltage between electrodes formed by the machining surface and the wire electrode to cause electric discharge. A wire electric discharge machining method for remachining a surface, comprising:
a state value detecting step of detecting a discharge state value indicating the state of the discharge occurring between the electrodes;
a driving control step of determining a traveling direction of the wire electrode relative to the workpiece based on the discharge state value and moving the wire electrode along the traveling direction at a constant speed relative to the workpiece;
including.

According to the present invention, wire electric discharge machining can be performed without using a machining program.

FIG. 1 is a schematic diagram showing the overall configuration of a wire electric discharge machine. FIG. 2 is a block diagram showing the configuration of the machining control system of the wire electric discharge machine 10. As shown in FIG. 3A to 3C are schematic diagrams showing advancing patterns of the wire electrode during machining. FIG. 4 is a schematic diagram showing the amount of change in the advancing direction of the wire electrode. FIG. 5 is a schematic diagram showing the amount of change in the advancing direction of the wire electrode. FIG. 6 is a schematic diagram showing the movement trajectory of the wire electrode. FIG. 7 is a flow chart showing the procedure of pre-processing. FIG. 8 is a flow chart showing the processing procedure. FIG. 9 is a schematic diagram showing a detected machining path and a generated machining path. FIG. 10 is a schematic diagram showing the detected machining path and the generated machining path.

BEST MODE FOR CARRYING OUT THE INVENTION A wire electric discharge machine and a wire electric discharge machining method according to the present invention will be described in detail below with preferred embodiments and with reference to the accompanying drawings.

[1. Overall configuration of wire electric discharge machine 10]
The overall configuration of the wire electric discharge machine 10 will be described with reference to FIG. The wire electric discharge machine 10 applies a voltage to the workpiece W (FIG. 2) and the wire electrode 12 in the machining fluid to generate electrical discharge between the gaps formed by the workpiece W and the wire electrode 12. It is a machine tool for performing electrical discharge machining on the workpiece W. The wire electric discharge machine 10 includes a machine main body 14 , a machining liquid processing device 16 and a control device 18 .

The material of the wire electrode 12 is, for example, a metallic material such as a tungsten system, a copper alloy system, or a brass system. On the other hand, the material of the workpiece W is, for example, a metal material such as an iron-based material or a superhard material.

The machine main body 14 includes a supply system 20 for supplying the wire electrode 12 toward the object W to be processed (work, workpiece), and a recovery system 22 for recovering the wire electrode 12 that has passed through the object W to be processed. .

The supply system 20 includes a wire bobbin 24 around which an unused wire electrode 12 is wound, a torque motor 26 that applies torque to the wire bobbin 24, and a brake shoe 28 that applies braking force to the wire electrode 12 by friction. , a brake motor 30 that applies braking torque to the brake shoe 28, a tension detector 32 that detects the magnitude of the tension of the wire electrode 12, and a wire guide that guides the wire electrode 12 above the workpiece W ( upper wire guide) 34. The torque motor 26 and the brake motor 30 are provided with encoders for detecting rotational positions or rotational speeds. The control device 18 feedback-controls the torque motor 26 and the brake motor 30 based on the detection signal detected by the encoder so that the rotation speed of the torque motor 26 and the brake motor 30 becomes a predetermined rotation speed.

The recovery system 22 includes a wire guide (lower wire guide) 36 that guides the wire electrode 12 below the workpiece W, pinch rollers 38 and feed rollers 40 that can pinch the wire electrode 12, and feed rollers 40. A torque motor 42 for applying torque and a collection box 44 for collecting used wire electrodes 12 transported by the pinch rollers 38 and the feed rollers 40 are provided. This torque motor 42 is provided with an encoder for detecting a rotational position or rotational speed. The control device 18 feedback-controls the torque motor 42 based on the detection signal detected by the encoder so that the rotation speed of the torque motor 42 reaches a predetermined rotation speed.

The machine main body 14 is provided with a machining tank 46 capable of storing machining fluid such as deionized water or oil used in electric discharge machining. This processing tank 46 is placed on a base portion 48 . Wire guides 34 and 36 are arranged in the machining tank 46 , and a workpiece W is provided between the wire guides 34 and 36 . The wire guides 34 , 36 have die guides 34 a , 36 a that support the wire electrode 12 . The wire guide 36 also includes a guide roller 36b that guides the wire electrode 12 to the pinch roller 38 and the feed roller 40 while changing the direction of the wire electrode 12. As shown in FIG.

The wire guide 34 ejects clean machining fluid containing no sludge (machining waste) toward the gap formed between the wire electrode 12 and the workpiece W. As shown in FIG. As a result, it is possible to fill the space between the gaps with a clean machining fluid suitable for electric discharge machining, and to prevent the accuracy of electric discharge machining from deteriorating due to sludge generated by electric discharge machining. Also, the wire guide 36 may also eject clean machining fluid containing no sludge toward the gap between the electrodes.

The workpiece W is supported by a table 50 (FIG. 2) movable in the X and Y directions. The wire guides 34 , 36 , the workpiece W, and the table 50 are immersed in the machining fluid stored in the machining tank 46 . The X and Y directions are orthogonal to each other.

The machining fluid treatment device 16 is a device that removes machining waste (sludge) generated in the machining tank 46 and controls the quality of the machining fluid by adjusting electrical resistivity, temperature, and the like. The machining fluid whose liquid quality is controlled by the machining fluid processing device 16 is returned to the machining tank 46 again, and the machining fluid is ejected from at least the wire guide 34 . The control device 18 controls the processing machine main body 14 and the processing liquid processing device 16 .

[2. Configuration of machining control system of wire electric discharge machine 10]
The configuration of the machining control system of the wire electric discharge machine 10 will be described with reference to FIG. The processing machine main body 14 has a table 50 , a drive section 52 , a discharge state detection section 54 and a power supply section 56 . On the other hand, the control device 18 has an operation section 74 , a storage section 80 and a calculation section 82 .

The table 50 supports the workpiece W. FIG. The drive unit 52 includes a servomotor 60x that outputs a driving force for moving the table 50 in the X direction, a servomotor 60y that outputs a driving force for moving the table 50 in the Y direction, and servomotors 60x and 60y. has a driving force transmission mechanism (not shown) for transmitting the driving force output by to the table 50, and a driver (not shown) for controlling the servomotors 60x and 60y. The servomotors 60x and 60y are provided with encoders 62x and 62y for detecting the drive amount. The encoders 62 x and 62 y output detection signals to the computing section 82 . In this embodiment, the wire electrode 12 is moved relative to the workpiece W by moving the table 50 . Alternatively, the wire electrode 12 may be moved.

The discharge state detector 54 detects a discharge state value indicating the state of discharge occurring between the electrodes. The discharge state value may be a voltage value between electrodes during discharge (referred to as an inter-electrode voltage value), may be a current flowing during discharge, or may be the number of discharge pulses detected within a unit time. may The discharge state detector 54 shown in FIG. 2 is connected to the workpiece W and the wire electrode 12 in order to detect the inter-electrode voltage value as the discharge state value. In the following description, the discharge state value is the inter-electrode voltage value. The discharge state detection unit 54 outputs the detected inter-electrode voltage value to the calculation unit 82 .

Based on the drive pulse signal generated by the discharge control section 86, the power supply section 56 repeatedly applies a voltage pulse to the workpiece W and the wire electrode 12 at predetermined intervals.

The operation unit 74 has an operation panel 76 and a screen 78 . The operation panel 76 and the screen 78 may be integrated like a touch panel or the like. The operation unit 74 outputs to the calculation unit 82 various information and a start signal input by the operator using the operation panel 76 . The various information includes machining conditions (material, thickness, wire diameter, re-machining amount of workpiece W, machining allowance, surface roughness, number of times of machining, etc.) and an initial traveling direction 100 of the wire electrode 12 (described later) (Fig. 6) and other information is included. The screen 78 displays operation guides and input various information.

The storage unit 80 is configured by a memory. The storage unit 80 stores a map (not shown) that associates processing conditions output from the operation unit 74 with control information corresponding to the processing conditions. The control information includes information such as the application condition of the voltage to be applied, the driving condition of the table 50, and the reference range for determining the magnitude of the inter-electrode voltage value (see [3] below). The application condition is information such as the voltage value of the applied voltage pulse (referred to as a voltage pulse) and the pulse interval. It should be noted that the pulse interval is the time between pulses, and is a rest time during which no voltage is applied to the workpiece W and the wire electrode 12 . The drive condition is information on the speed at which the wire electrode 12 is moved with respect to the object W to be processed.

The calculation unit 82 is configured by a processor such as a CPU. The calculation unit 82 functions as a drive control unit 84 , a discharge control unit 86 and a path detection unit 88 by executing programs stored in the storage unit 80 .

The drive control unit 84 determines the traveling direction of the wire electrode 12 with respect to the workpiece W based on the inter-electrode voltage value when the machining surface S is re-machined, and moves the wire electrode 12 with respect to the workpiece W at a constant speed. Move along the direction of travel. The drive control unit 84 reads from the storage unit 80 speed information corresponding to the processing conditions output from the operation unit 74 . The drive control section 84 outputs a numerical control signal for moving the table 50 to the driver of the drive section 52 .

The discharge control unit 86 reads from the storage unit 80 application conditions corresponding to the machining conditions output from the operation unit 74, and generates a drive pulse signal for driving the power supply unit 56 so as to apply voltage under the application conditions. do. The discharge control section 86 outputs the generated drive pulse signal to the power supply section 56 .

The path detection unit 88 detects the machining position of the workpiece W based on the detection signals output from the encoders 62x and 62y. The path detection unit 88 causes the storage unit 80 to store position information indicating the machining position.

[3. Operation of wire electric discharge machine 10]
The operation of the wire electric discharge machine 10 according to this embodiment will be described with reference to FIGS. 3A to 3C. The wire electric discharge machine 10 re-machines the machined surface S of the workpiece W that has been machined once or more without using a machining program. In other words, the wire electric discharge machine 10 does not advance the wire electrode 12 using a machining program, but estimates the position of the wire electrode 12 with respect to the machining surface S based on the state of electric discharge generated between the electrodes, The wire electrode 12 is advanced while automatically adjusting the distance between the electrodes.

The inter-electrode voltage value increases (becomes a large value) as the distance from the processing surface S increases in the vertical direction. That is, there is a correlation between the distance between the electrodes and the voltage value between the electrodes. On the other hand, the inter-electrode voltage value changes according to the relative speed of the wire electrode 12 with respect to the workpiece W. FIG. In view of these characteristics, the drive control unit 84 keeps the relative speed of the wire electrode 12 with respect to the workpiece W constant, suppresses the change in the inter-electrode voltage value due to the speed change, and based on the inter-electrode voltage value The position of the wire electrode 12 with respect to the machining surface S is estimated.

As shown in FIGS. 3A to 3C, there is an optimum position (referred to as optimum position 90) of the wire electrode 12 in a direction away from the machining surface S in its vertical direction. There is a range suitable for processing (referred to as an optimal range 92) on the side closer to and further from the processing surface S than the optimal position 90 as the center. When discharge occurs at the boundary position 92a closest to the machined surface S in the optimum range 92, the inter-electrode voltage value is relatively low. On the other hand, when the discharge occurs at the boundary position 92b farthest from the machining surface S in the optimum range 92, the inter-electrode voltage value becomes relatively high. In this way, the voltage value (inter-electrode voltage value) of the discharge generated when the wire electrode 12 is positioned in the optimum range 92 has a range.

In the present embodiment, the range of voltage values of discharge generated when the wire electrode 12 moves through the optimum range 92 at a constant speed is referred to as a reference range. Also, the voltage value of the discharge generated when the wire electrode 12 moves at the boundary position 92a at a constant speed is referred to as the lower limit. Further, the voltage value of discharge generated when the wire electrode 12 moves at a constant speed across the boundary position 92b is referred to as an upper limit value.

The drive control unit 84 compares the inter-electrode voltage value detected by the discharge state detection unit 54 (specifically, the average value of inter-electrode voltage values per unit time) with the upper limit value and the lower limit value of the reference range. While doing so, the traveling direction of the wire electrode 12 is automatically adjusted. The upper limit value and lower limit value of the reference range are stored in advance in the storage unit 80 .

For example, as shown in FIG. 3A, when a discharge occurs when the wire electrode 12 is positioned within the optimum range 92, the inter-electrode voltage value (average value) falls within the reference range. At this time, the advancing direction of the wire electrode 12 is maintained as indicated by the arrow 94a.

For example, as shown in FIG. 3B, when electrical discharge occurs when the wire electrode 12 exceeds the boundary position 92b of the optimum range 92 and is moving away from the machining surface S, the inter-electrode voltage value (average value) is the upper limit value surpass. At this time, the traveling direction of the wire electrode 12 is changed to approach the machining surface S as indicated by an arrow 94b.

For example, as shown in FIG. 3C, when electrical discharge occurs when the wire electrode 12 crosses the boundary position 92a of the optimum range 92 and approaches the machining surface S, the inter-electrode voltage value (average value) is the lower limit value. below. At this time, the advancing direction of the wire electrode 12 is changed in the direction away from the machining surface S as indicated by the arrow 94c.

As shown in FIG. 4, the change amount (angle) of the traveling direction may be a predetermined angle θ1. Further, as shown in FIG. 5, the amount of change (angle) in the traveling direction may be determined according to the magnitude of the inter-electrode voltage value (average value). For example, the greater the difference between the inter-electrode voltage value (average value) and the lower limit value or upper limit value, the larger the change amount (angle θ2) of the direction of travel may be.

[4. Processing flow for reprocessing]
A series of processes performed when the workpiece W is reprocessed will be described with reference to FIGS. 6 to 8. FIG.

[4.1. Pre-processing performed by the operator]
The operator sets the workpiece W to be reprocessed on the table 50 . Further, the operator operates the operation unit 74 to set the machining conditions, and also sets the initial traveling direction 100 and either the first direction 102 or the second direction 104 . As shown in FIG. 6 , the initial advancing direction 100 is the direction in which the wire electrode 12 approaches the workpiece W set at a position distant from the wire electrode 12 .

A first direction 102 and a second direction 104 pivot the direction of travel of the wire electrode 12 moving along the initial direction of travel 100 when the wire electrode 12 reaches a position suitable for reworking the workpiece W. is the direction. When the traveling direction is directed in the first direction 102 , the machining surface S is located on the left side when viewed from the wire electrode 12 . On the other hand, when the traveling direction is directed in the second direction 104 , the machined surface S is located on the right side as viewed from the wire electrode 12 . Once the first direction 102 or the second direction 104 is determined, the direction in which the wire electrode 12 is brought closer and the direction in which the wire electrode 12 is moved away from the machining surface S are specified. The first direction 102 is defined within a range greater than 0 degrees and less than +180 degrees with respect to the initial heading 100, and the second direction 104 is less than 0 degrees and less than -180 degrees with respect to the initial heading 100. is defined within the range of

[4.2. Pre-processing performed by wire electric discharge machine 10]
After making various settings, the operator operates a trajectory switch (not shown) of the operation unit 74 . Then, an activation signal is output from the operation unit 74 to the calculation unit 82, and the pre-processing shown in FIG. 7 is started. At this time, the drive control unit 84 reads information on the drive conditions and the reference range corresponding to the set processing conditions from the storage unit 80 . The discharge control unit 86 reads the application conditions corresponding to the set machining conditions from the storage unit 80 .

In step S<b>1 , the drive control section 84 generates a numerical control signal for relatively moving the wire electrode 12 in the initial traveling direction 100 and outputs it to the drive section 52 . The drive unit 52 drives the servomotors 60x and 60y to relatively move the wire electrode 12 along the initial traveling direction 100, thereby bringing the workpiece W and the wire electrode 12 closer together. At this time, the drive control unit 84 sets the moving speed of the wire electrode 12 to the speed indicated by the drive conditions. At the same time, the discharge control section 86 generates a drive pulse signal according to the application conditions and outputs it to the power supply section 56 . The power supply unit 56 applies a pulse voltage between the workpiece W and the wire electrode 12 . After step S1 ends, the process proceeds to step S2.

In step S2, the drive control unit 84 calculates an average value of inter-electrode voltage values per unit time. When the workpiece W and the wire electrode 12 approach each other to some extent, electric discharge occurs between the electrodes, and as the distance between the electrodes decreases, the voltage between the electrodes decreases and the average value also decreases. After step S2 ends, the process proceeds to step S3.

In step S<b>3 , the drive control unit 84 compares the average value calculated in step S<b>2 with the upper limit value of the reference range read from the storage unit 80 . If the average value is below the upper limit of the reference range (step S3: YES), that is, if the wire electrode 12 reaches the optimum range 92, the process proceeds to step S4. On the other hand, if the average value is equal to or greater than the upper limit value of the reference range (step S3: NO), that is, if the wire electrode 12 has not reached the optimum range 92, the process returns to step S1.

In step S<b>4 , the drive control section 84 directs the traveling direction of the wire electrode 12 with respect to the workpiece W to either the first direction 102 or the second direction 104 output from the operation section 74 . At this time, the path detection section 88 detects the position of the wire electrode 12 based on the detection signals output from the encoders 62x and 62y. Then, the path detection unit 88 stores the position in the storage unit 80 as the machining start position. With the above, the pre-processing is finished.

[4.3. Machining processing performed by wire electric discharge machine 10]
After the pre-processing shown in FIG. 7 is finished, the processing shown in FIG. 8 is started.

In step S11, the drive control unit 84 outputs a numerical control signal for relatively moving the wire electrode 12 along the traveling direction set at that time (for example, the arrows 106a, 106b, and 106c shown in FIG. 6). It generates and outputs it to the drive unit 52 . The drive unit 52 drives the servomotors 60x and 60y to relatively move the wire electrode 12 along the traveling direction. At the same time, the discharge control section 86 generates a drive pulse signal according to the application condition read from the storage section 80 and outputs it to the power supply section 56 . The power supply unit 56 applies a pulse voltage between the workpiece W and the wire electrode 12 . After the end of step S11, the process proceeds to step S12.

In step S12, the drive control unit 84 calculates an average value of inter-electrode voltage values per unit time. When the traveling direction of the wire electrode 12 approaches the workpiece W, the average value is low. When the traveling direction of the wire electrode 12 is the direction away from the workpiece W, the average value is high. After step S12 ends, the process proceeds to step S13.

In step S<b>13 , the drive control unit 84 compares the average value calculated in step S<b>12 with the upper limit value of the reference range read from the storage unit 80 . If the average value exceeds the upper limit of the reference range (step S13: YES), that is, if the wire electrode 12 is far from the workpiece W and away from the optimum range 92 as shown in FIG. goes to step S14. On the other hand, if the average value is equal to or less than the upper limit of the reference range (step S13: NO), the process proceeds to step S15.

In step S14, the drive control unit 84 brings the workpiece W and the wire electrode 12 close to each other. At this time, as shown in FIG. 3B, the drive control unit 84 changes the advancing direction of the wire electrode 12 to a direction approaching the machining surface S as indicated by an arrow 94b. After step S14 ends, the process proceeds to step S17.

In step S<b>15 , the drive control unit 84 compares the average value calculated in step S<b>12 with the lower limit value of the reference range read from the storage unit 80 . If the average value is below the lower limit of the reference range (step S15: YES), that is, if the wire electrode 12 is close to the workpiece W and away from the optimum range 92 as shown in FIG. goes to step S16. On the other hand, if the average value is equal to or greater than the lower limit of the reference range (step S15: NO), that is, if the wire electrode 12 is positioned within the optimum range 92 as shown in FIG. 3A, the process proceeds to step S17. At this time, the drive control unit 84 maintains the advancing direction of the wire electrode 12 as indicated by the arrow 94a.

In step S16, the drive control unit 84 keeps the workpiece W and the wire electrode 12 away. At this time, as shown in FIG. 3C, the drive control unit 84 changes the traveling direction of the wire electrode 12 to move away from the machining surface S as shown by an arrow 94c. After step S16 ends, the process proceeds to step S17.

In step S17, the path detection section 88 detects the machining position of the wire electrode 12 based on the detection signals output from the encoders 62x and 62y. Then, the path detection unit 88 causes the storage unit 80 to store the machining position as the machining path 110 (FIG. 9). After the end of step S17, the process proceeds to step S18.

In step S18, the drive control unit 84 determines whether or not the machining has ended. For example, after starting machining and moving the wire electrode 12 by a predetermined distance, the drive control unit 84 terminates machining when the machining position detected by the path detection unit 88 reaches within a predetermined range of the machining end position. It is determined that The machining end position may be input by the operator through the operation unit 74 . Further, when the processing surface S of the workpiece W is annular, the processing end position may be the processing start position stored in the storage unit 80 . If the processing has ended (step S18: YES), the series of processes ends. On the other hand, if the machining has not ended (step S18: NO), the process returns to step S11.

[5. Modification]
The accuracy of the machined surface S is improved by performing the re-machining process a plurality of times. It is possible to perform the processing described using FIG. 8 multiple times. Alternatively, the machining path 110 (FIG. 9) detected in the nth reworking process can be used in the n+1th and subsequent reworking processes.

For example, as shown in FIG. 9, the drive control unit 84 interpolates the n-th machining path 110 at the time of the n+1-th machining process, and performs a new machining that is closer to the machining surface S by the amount of the machining allowance. Generate path 112 . Then, the drive control unit 84 moves the wire electrode 12 with reference to the machining path 112 . At this time, the drive control unit 84 corrects the traveling direction while performing a series of processes shown in FIG.

Further, the drive control unit 84 detects the intermediate coordinates of the machining path 110, generates a machining path 110' by interpolating each intermediate coordinate, and further brings the machining path 110' closer to the machining surface S by the machining allowance. machining path 112 may be generated. As shown in FIG. 10, the intermediate coordinate is the average value of the coordinates of the machining path 110 existing within a predetermined length L along the machining surface S. As shown in FIG. Then, the drive control unit 84 moves the wire electrode 12 with reference to the machining path 112 . At this time, the drive control unit 84 corrects the traveling direction while performing a series of processes shown in FIG.

By repeatedly performing machining using the machining path 112 , the machining accuracy is improved and wasteful operation of the wire electrode 12 is eliminated.

[6. Invention obtained from the embodiment]
Inventions that can be understood from the above embodiments will be described below.

A first aspect of the present invention is
While relatively moving the wire electrode 12 along the machining surface S of the workpiece W, a voltage is applied between the electrodes formed by the machining surface S and the wire electrode 12 to cause electric discharge, whereby the machining surface S is changed. A wire electric discharge machine 10 for remachining,
a discharge state detection unit 54 for detecting a discharge state value indicating the state of discharge occurring between the electrodes;
A drive control unit that determines the traveling direction of the wire electrode 12 with respect to the workpiece W based on the discharge state value, and moves the wire electrode 12 along the traveling direction at a constant speed with respect to the workpiece W. 84 and
Prepare.

According to the above configuration, since the wire electrode 12 is relatively moved at a constant speed, the position of the wire electrode 12 with respect to the machining surface S can be estimated based on the inter-electrode voltage value. That is, according to the above configuration, it is possible to determine the advancing direction of the wire electrode 12 with respect to the processing surface S, that is, whether the wire electrode 12 should be moved closer to or away from the processing surface S. Therefore, wire electric discharge machining can be performed without using a machining program. Therefore, work becomes simple.

In addition, the workpiece W that has been processed once, such as rough processing, can be removed from the machine and then subjected to finish processing. In the case of a conventional wire electric discharge machine, it is necessary to re-fix the workpiece W in the same position as when it was removed. On the other hand, in the case of the wire electric discharge machine 10 according to the first aspect, the workpiece W may be fixed at any position on the table 50 . This also makes the work easier.

In a first aspect,
The discharge state detection unit 54 may detect any one of a voltage value, a current value, and the number of pulses as the discharge state value.

In a first aspect,
The drive control unit 84 may calculate an average value of the discharge state values per unit time, and determine the traveling direction based on the average value.

In a first aspect,
The drive control unit 84 compares the average value with a preset reference range, and changes the traveling direction to a direction to move the wire electrode 12 closer to or away from the workpiece W according to the comparison result. You can change it.

In a first aspect,
The drive control section 84 may change the traveling direction by a predetermined amount (angle θ1).

According to the above configuration, it is possible to simplify the process of changing the traveling direction.

In a first aspect,
The drive control unit 84 may increase the change amount (angle θ2) of the traveling direction as the difference between the average value and the reference range increases.

According to the above configuration, the advancing direction of the wire electrode 12 can follow the processing surface S even if the extending direction of the processing surface S changes greatly.

In a first aspect,
The drive control unit 84 causes the workpiece W and the wire electrode 12 to approach each other before starting the re-machining of the machining surface S, and when the average value reaches the reference range, the progress The direction may be directed to either a first direction 102 in which the processing surface S is positioned on the left side as viewed from the wire electrode 12 or a second direction 104 in which the processing surface S is positioned on the right side.

According to the above configuration, re-machining of the processing surface S can be automatically started regardless of the position of the workpiece W before processing.

In a first aspect,
An operation unit 74 that sets either the first direction 102 or the second direction 104 according to an input operation may be further provided.

In a first aspect,
further comprising a path detection unit 88 for detecting a machining path 110 passed by the wire electrode 12 during the n (n is an integer) re-machining of the machining surface S,
The drive control unit 84 sets the traveling direction based on the machining path 110 detected during the n+1 re-machining at the time of n+1 re-machining, and sets the traveling direction based on the discharge state value. may be corrected.

According to the above configuration, a smoother machined surface S can be achieved. Furthermore, according to the above configuration, the wire electrode 12 can be efficiently operated with respect to the workpiece W during the (n+1)th re-machining.

A second aspect of the present invention is
Using the wire electric discharge machine 10, the wire electrode 12 is relatively moved along the machining surface S of the workpiece W, and a voltage is applied between the electrodes formed by the machining surface S and the wire electrode 12. A wire electric discharge machining method for re-machining the machined surface S by causing electric discharge,
a state value detecting step (step S12) of detecting a discharge state value indicating the state of the discharge occurring between the electrodes;
A drive control step of determining the traveling direction of the wire electrode relative to the workpiece based on the discharge state value and moving the wire electrode along the traveling direction at a constant speed relative to the workpiece (step S13) ~ step S16);
including.

According to the above configuration, like the first aspect, wire electric discharge machining can be performed without using a machining program.

It goes without saying that the wire electric discharge machine and the wire electric discharge machining method according to the present invention are not limited to the above-described embodiments, and various configurations can be adopted without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 10... Wire electric discharge machine 12... Wire electrode 54... Discharge state detection part 74... Operation part 84... Drive control part 88... Path detection part W... Workpiece S... Machining surface

Claims (8)

Wire electric discharge machining for re-machining the machined surface by applying a voltage between the gap formed by the machined surface and the wire electrode while relatively moving the wire electrode along the machined surface of the object to be machined to cause electric discharge. machine and
The upper limit value and the lower limit value of the discharge state value indicating the state of the discharge generated between the electrodes when the wire electrode moves away from the machining surface in the vertical direction and in a range suitable for machining at a constant speed are stored in advance. a storage unit;
a discharge state detection unit that detects the discharge state value;
determining a traveling direction of the wire electrode relative to the workpiece based on the discharge state value; moving the wire electrode relative to the workpiece along the traveling direction at a constant speed; calculating an average value of the discharge state values, changing the advancing direction so as to bring the workpiece and the wire electrode closer to each other when the average value exceeds the upper limit value, wherein the average value exceeds the lower limit value; a drive control unit that changes the direction of movement so as to move the workpiece and the wire electrode away from each other when falling below ;
A wire electric discharge machine, comprising: The wire electric discharge machine according to claim 1,
The wire electric discharge machine, wherein the discharge state detection unit detects any one of a voltage value, a current value, and the number of pulses as the discharge state value. The wire electric discharge machine according to claim 1 ,
The wire electric discharge machine, wherein the drive control unit changes the traveling direction by a predetermined amount. The wire electric discharge machine according to claim 1 ,
The wire electric discharge machine, wherein the drive control unit increases the change amount of the traveling direction as the difference between the average value and the upper limit value or the difference between the average value and the lower limit value increases. The wire electric discharge machine according to any one of claims 1 to 4 ,
The drive control unit causes the workpiece and the wire electrode to approach each other before starting re-machining of the machined surface, and when the average value reaches the upper limit value or when the average value and the lower limit value are reached. and the traveling direction is directed to either a first direction in which the machined surface is positioned on the left side or a second direction in which the machined surface is positioned on the right side as viewed from the wire electrode. . The wire electric discharge machine according to claim 5 ,
A wire electric discharge machine, further comprising an operation unit that sets either the first direction or the second direction according to an input operation. The wire electric discharge machine according to any one of claims 1 to 6 ,
further comprising a path detection unit that detects a machining path passed by the wire electrode during n (n is an integer) re-machining of the machining surface;
The drive control unit sets the advancing direction based on the machining path detected during the n+1th re-machining, and corrects the set advancing direction based on the discharge state value at the time of n+1 re-machining. , wire electric discharge machine. A wire electric discharge machine is used to relatively move a wire electrode along a machining surface of an object to be machined, and apply a voltage between electrodes formed by the machining surface and the wire electrode to cause electric discharge. A wire electric discharge machining method for remachining a surface, comprising:
Upper and lower limits of discharge state values indicating the state of discharge generated between the electrodes when the wire electrode moves at a constant speed through a range suitable for machining and separated from the machining surface in the vertical direction are stored in advance. process and
a state value detecting step of detecting the discharge state value;
determining a traveling direction of the wire electrode relative to the workpiece based on the discharge state value; moving the wire electrode relative to the workpiece along the traveling direction at a constant speed; calculating an average value of the discharge state values, changing the advancing direction so as to bring the workpiece and the wire electrode closer to each other when the average value exceeds the upper limit value, wherein the average value exceeds the lower limit value; a drive control step of changing the direction of travel so as to move the workpiece and the wire electrode away from each other when falling below ;
A method of wire electrical discharge machining, comprising:

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