Wire electric discharge machine and wire electric discharge machining method

Abstract

The present disclosure is a wire electric discharge machine that moves a wire electrode along a machining path and machines an object to be machined in accordance with machining conditions, the wire electric discharge machine being provided with: a first wire guide and a second wire guide that support the wire electrode; a sensor that detects the wire electrode in an intersecting direction that intersects a feeding direction in which the wire electrode is fed; a calculation unit that calculates the amount of displacement of the position of the wire electrode in the intersecting direction on the basis of the detection result of the sensor; and an adjustment unit that adjusts the machining condition or the machining path on the basis of the displacement amount.

Description

Technical Field

[0001] This disclosure relates to a wire electrical discharge machining (EDM) machine and a wire electrical discharge machining (EDM) method. Background Technology

[0002] International Publication No. 2014 / 068681 discloses a wire electrical discharge machining apparatus that reduces machining contour errors by correcting the positional displacement of the wire electrode. Summary of the Invention

[0003] The aim is to suppress the reduction in machining accuracy caused by the displacement of the wire electrode during electrical discharge machining.

[0004] The first aspect of this disclosure is a wire electrical discharge machining (EDM) machine that moves a wire electrode along a machining path relative to a workpiece and generates a discharge between the workpiece and the wire electrode according to machining conditions, thereby machining the workpiece. The wire EDM machine includes: a first wire guide that supports the wire electrode below the workpiece; a second wire guide that supports the wire electrode above the workpiece; a sensor disposed on at least one of the first and second wire guides that detects the wire electrode along a cross direction intersecting the delivery direction of the wire electrode; a calculation unit that calculates the displacement of the wire electrode's position in the cross direction based on the sensor's detection result; and an adjustment unit that adjusts the machining conditions or the machining path based on the displacement.

[0005] The second aspect of this disclosure is a wire electrical discharge machining (EDM) method performed by a wire EDM machine, the wire EDM machine comprising: a first wire guide that supports a wire electrode below a workpiece; a second wire guide that supports the wire electrode above the workpiece; and a sensor disposed on at least one of the first and second wire guides, detecting the wire electrode along an intersecting direction that intersects with the delivery direction of the wire electrode. The wire EDM machine moves the wire electrode relative to the workpiece along a machining path and generates a discharge between the workpiece and the wire electrode according to machining conditions, thereby machining the workpiece. The wire EDM method includes: a calculation step of calculating a displacement of the position of the wire electrode in the intersecting direction based on the detection result of the sensor; and an adjustment step of adjusting the machining conditions or the machining path according to the displacement. Attached Figure Description

[0006] Figure 1 This is a diagram illustrating one embodiment of a wire electrical discharge machining (EDM) machine.

[0007] Figure 2 This is an enlarged view of the sensor holding section.

[0008] Figure 3 This is a block diagram showing a part of the components of a wire electrical discharge machining (EDM) machine.

[0009] Figure 4A , Figure 4B and Figure 4C This is a graph used to illustrate the sensor detection results corresponding to the displacement of the wire electrode position during processing.

[0010] Figure 5 This is a diagram illustrating the process performed as an adjustment of processing conditions.

[0011] Figure 6 This is a flowchart illustrating an example of the processing sequence in a wire electrical discharge machining (WEDM) method. Detailed Implementation

[0012] In existing wire electrical discharge machining (EDM) machines, machining conditions are modified during EDM based on information about the machining path determined by a pre-stored machining program. However, sometimes the actual machined shape differs from the shape indicated by the machining path information. For example, the actual machined shape may differ from the shape indicated by the machining path information due to wire electrode displacement caused by the discharge action or machining hydraulic pressure during EDM.

[0013] Therefore, in cases where multiple cycles of finishing are performed on a workpiece, the amount of machining done in the preceding cycle may become too much or too little. However, if such actual machining shapes are not considered in subsequent electrical discharge machining, the machining accuracy of the workpiece may be reduced.

[0014] Figure 1 This is a diagram illustrating one embodiment of a wire electrical discharge machining (EDM) machine 10. Figure 1 The X, Y, and Z directions shown are orthogonal to each other, with the Z direction being the direction of gravity. However, the positive direction of the Z direction is opposite to the positive direction of gravity. The wire electrical discharge machining (EDM) machine 10 includes a main body 20, a control device 30, and a processing power supply 40. The processing power supply 40 applies a voltage to the electrode space between the wire electrode E and the workpiece W to generate a discharge. Depending on the processing conditions, the wire EDM machine 10 performs electrical discharge machining on the workpiece W through the discharge generated between the electrodes.

[0015] During electrical discharge machining, the control device 30 moves the wire electrode E relative to the workpiece W along the machining path specified by the machining program (machining program 122r described later). The workpiece W is supported on the worktable 62. The relative movement of the wire electrode E and the workpiece W is achieved, for example, by moving the worktable 62 in the X and Y directions.

[0016] The main body 20 of the wire electrical discharge machine 10 has a first wire guide 64 and a second wire guide 66 as a pair of wire guides that are separate from each other. Figure 1 In the example shown, the first wire guide 64 and the second wire guide 66 are located along the direction of gravity (Z direction). Both the first wire guide 64 and the second wire guide 66 can move in the X and Y directions.

[0017] The first wire guide 64 includes a first guide block 68, a first guide wheel 70, and a first nozzle 72. The second wire guide 66 includes a second guide block 74, a second guide wheel 76, and a second nozzle 78. The first wire guide 64 supports the wire electrode E below the worktable 62 and the workpiece W (in the -Z direction relative to the workpiece W). The second wire guide 66 supports the wire electrode E above the worktable 62 and the workpiece W (in the +Z direction relative to the workpiece W).

[0018] The wire electrode E is supplied from the winding tube 80 at a speed determined as one of the processing conditions described later. The wire electrode E is fed via the roller 82 to the second wire guide 66, the workpiece W, and the first wire guide 64. When the second wire guide 66 and the first wire guide 64 are positioned along the direction of gravity (-Z direction), the feeding direction of the wire electrode E is also the direction of gravity (-Z direction).

[0019] The delivered wire electrode E passes through the second wire guide 66, the workpiece W, and the first wire guide 64, and is held by the pinch roller 84 and the feed roller 86. The wire electrode E held by the pinch roller 84 and the feed roller 86 is recovered by the recovery box 88.

[0020] When performing electrical discharge machining on the workpiece W, the machining tank 90 of the main body 20 can also store machining fluid. In this case, the worktable 62, the workpiece W, the first wire guide 64, and the second wire guide 66 are immersed in the machining fluid. The machining tank 90 is mounted on the base 92 of the main body 20. Machining fluid supplied by a machining fluid supply device (not shown) is ejected from the first nozzle 72 of the first wire guide 64 and the second nozzle 78 of the second wire guide 66.

[0021] The sensor holding part 98 is mounted on at least one of the first wire guide 64 and the second wire guide 66. Figure 2 This is an enlarged view of the sensor holding section 98. Two sensors 98x and 98y for detecting the wire electrode E are mounted on the sensor holding section 98. In this embodiment, two sensors 98x and 98y are provided on the first wire guide 64, which supports the wire electrode E below the workpiece W. The sensor holding section 98 functions as a mounting section for mounting the two sensors 98x and 98y on the first wire guide 64.

[0022] Furthermore, each of the two sensors 98x and 98y only needs to detect the wire electrode E at any position from the first wire guide 64 to the second wire guide 66. Therefore, as shown in this embodiment, two sensors 98x and 98y can be provided on the first wire guide 64. However, two sensors 98x and 98y can also be provided on the second wire guide 66, which supports the wire electrode E above the workpiece W. Alternatively, two sensors 98x and 98y can be provided on both the first wire guide 64 and the second wire guide 66.

[0023] In the first wire guide 64, the first guide wheel 70 and the first nozzle 72 are supported by the first guide block 68. A sensor holding part 98 is mounted on the first nozzle 72. Therefore, the two sensors 98x and 98y are located between the first wire guide 64 and the second wire guide 66, and are located slightly away from the position of the wire electrode E supported by the first wire guide 64 in the +Z direction.

[0024] The sensor holding part 98 has a through hole at or near its center for inserting the wire electrode E. The processing fluid ejected from the first nozzle 72 is supplied through this through hole to the electrode space between the wire electrode E and the workpiece W.

[0025] Sensor 98x detects the X-direction electrode E along the first intersection direction (-Z direction) that intersects the output direction of the output electrode E. Sensor 98y detects the Y-direction electrode E along the second intersection direction (-Z direction) that intersects the output direction of the output electrode E.

[0026] In this embodiment, sensor 98x is an optical fiber sensor that detects line electrode E along the X direction. Sensor 98x has a light-emitting fiber 98xt that projects light from a light source in the Y direction, and a light-receiving fiber 98xr that receives light projected by the light-emitting fiber 98xt. The light-emitting end of the light-emitting fiber 98xt and the light-receiving end of the light-receiving fiber 98xr are arranged facing each other in the Y direction. Line electrode E, which extends in the -Z direction, is located between the light-emitting end of the light-emitting fiber 98xt and the light-receiving end of the light-receiving fiber 98xr.

[0027] Similar to sensor 98x, sensor 98y is an optical fiber sensor that detects the line electrode E along the Y direction. Sensor 98y has a light-emitting fiber 98yt that projects light from a light source in the X direction, and a light-receiving fiber 98yr that receives the light projected by the light-emitting fiber 98yt. The light-emitting end of the light-emitting fiber 98yt and the light-receiving end of the light-receiving fiber 98yr are arranged facing each other in the X direction. The line electrode E, which extends in the -Z direction, is located between the light-emitting end of the light-emitting fiber 98yt and the light-receiving end of the light-receiving fiber 98yr.

[0028] Figure 3 This is a block diagram showing a portion of the configuration of a wire electrical discharge machining (EDM) machine 10. The EDM machine 10 also has... Figure 1 The worktable drive unit 102, electrode delivery drive unit 104, machining fluid supply device 106, and signal processing device 110 are not shown in the diagram. The machining power supply 40 repeatedly applies pulse voltages between the online electrode E and the workpiece W.

[0029] The table drive unit 102 drives the table 62. This allows the wire electrode E to move relative to the workpiece W in the X and Y directions. The table drive unit 102 includes an X-motor, a Y-motor, an X-drive transmission mechanism, and a Y-drive transmission mechanism. The X-motor is used to move the table 62 in the X direction. The Y-motor is used to move the table 62 in the Y direction.

[0030] The X-drive transmission mechanism is used to convert the rotary motion of the X-motor into linear motion in the X direction of the worktable 62. The Y-drive transmission mechanism is used to convert the rotary motion of the Y-motor into linear motion in the Y direction of the worktable 62. Both the X-drive transmission mechanism and the Y-drive transmission mechanism may include a ball screw and a nut engaged with the ball screw. Furthermore, each of the X-motor and Y-motor is equipped with an encoder (rotational position detection sensor) for detecting the rotational position.

[0031] Electrode delivery drive unit 104 has Figure 1 The roller 82, pinch roller 84, and feed roller 86 are shown, along with a delivery motor and a recovery motor (not shown). The delivery motor rotates roller 82. The recovery motor rotates pinch roller 84 and feed roller 86. Each of the delivery motor and recovery motor is equipped with an encoder (rotation position detection sensor) for detecting rotational position.

[0032] Roller 82, by rotating, feeds the wire electrode E wound on the winding tube 80 toward the second wire guide 66, the workpiece W, and the first wire guide 64. Pinch roller 84 and feed roller 86 apply tension to the wire electrode E by clamping it. In this state, pinch roller 84 and feed roller 86 further rotate to feed the wire electrode E toward and collect it back into the recycling bin 88.

[0033] The machining fluid supply device 106 supplies machining fluid to the electrode space between the wire electrode E and the workpiece W. Therefore, the machining fluid from the machining fluid supply device 106 is ejected from the first nozzle 72 of the first wire guide 64 and the second nozzle 78 of the second wire guide 66. Alternatively, the machining fluid may be ejected from only one of the first nozzle 72 of the first wire guide 64 and the second nozzle 78 of the second wire guide 66.

[0034] Furthermore, the processing fluid supply device 106 not only supplies processing fluid to the electrode space between the wire electrode E and the workpiece W, but also supplies processing fluid to the processing tank 90 without passing through the first nozzle 72 and the second nozzle 78. Additionally, the processing fluid supply device 106 may include a wastewater tank and a clean water tank (neither shown). The wastewater tank stores processing fluid containing waste residue discharged from the processing tank 90. ​​The clean water tank stores processing fluid supplied from the wastewater tank, and is processing fluid for which waste residue has been removed by a filter (not shown).

[0035] The signal processing device 110 includes a light source 112, a light-receiving element 114, and a signal processing circuit 116. Light emitted from the light source 112 is transmitted within the projection fiber 98xt of the sensor 98x and projected from the projection end through the projection fiber 98xt. If a portion of the projected light is blocked by the line electrode E, the remaining portion of the projected light that is not blocked is received at the light-receiving end of the sensor 98x by the light-receiving fiber 98xr and transmitted within the light-receiving fiber 98xr. The light received by the light-receiving fiber 98xr is detected by the light-receiving element 114.

[0036] The signal processing circuit 116 generates a sensor signal representing the detection result of the sensor 98x based on the detection of light by the light receiving element 114. The detection result of the sensor 98x includes the amount of light received by the light receiving optical fiber 98xr.

[0037] exist Figure 3 Only sensor 98x is shown in the diagram; sensor 98y is omitted. In sensor 98y, similarly to sensor 98x, the light-receiving element 114 detects the remaining portion of the light projected from the light source 112 that is not blocked by the line electrode E. Signal processing circuit 116 generates a sensor signal representing the detection result of sensor 98y, which includes the amount of light received by the light-receiving optical fiber 98yr.

[0038] The signal processing circuit 116 transmits a sensor signal representing the detection result of the sensor 98x and a sensor signal representing the detection result of the sensor 98y to the control device 30. Alternatively, the signal processing circuit 116 may also generate a single sensor signal representing the detection results of both the sensor 98x and the sensor 98y, and transmit this sensor signal to the control device 30.

[0039] The control device 30 includes an arithmetic unit 120 and a storage unit 122. The arithmetic unit 120 includes a processor such as a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit). That is, the arithmetic unit 120 includes processing circuitry.

[0040] The storage unit 122 includes volatile memory such as RAM (Random Access Memory) and non-volatile memory such as ROM (Read Only Memory) or flash memory. The volatile memory serves as the processor's working memory. The non-volatile memory stores necessary data such as the processing program 122r executed by the processor and processing condition data 122c.

[0041] The machining program 122r determines the machining path when machining the workpiece W. The machining condition data 122c determines the various machining conditions used to machine the workpiece W. Regarding these various machining conditions, use... Figure 5 To be described later.

[0042] The arithmetic unit 120 includes a machining control unit 150, a calculation unit 152, and an adjustment unit 154. The arithmetic unit 120 executes the program stored in the storage unit 122 to realize the machining control unit 150, the calculation unit 152, and the adjustment unit 154.

[0043] At least a portion of the processing control unit 150, the calculation unit 152, and the adjustment unit 154 can be implemented by integrated circuits such as ASIC (Application Specific Integrated Circuit) or FPGA (Field Programmable Gate Array), or by electronic circuits containing discrete devices.

[0044] The machining control unit 150 performs control related to the electrical discharge machining of the workpiece W. Specifically, the machining control unit 150 moves the workpiece W and the wire electrode E relative to each other and generates a discharge between them. The machining control unit 150 includes a table drive control unit 182, an electrode delivery control unit 184, a machining fluid supply control unit 186, and a power supply control unit 188.

[0045] The table drive control unit 182 controls the table drive unit 102 to move the table 62 supporting the workpiece W in the X and Y directions. By moving the table 62 in the X and Y directions, the wire electrode E can be moved relative to the workpiece W in the X and Y directions.

[0046] Therefore, the table drive control unit 182 controls the table drive unit 102 to move the wire electrode E relative to the machining path. This machining path is the machining path specified by the machining program 122r, or, as described later, the machining path adjusted by the adjustment unit 154.

[0047] The electrode delivery control unit 184 controls the electrode delivery drive unit 104 to deliver the wire electrode E to the workpiece W and retrieve it into the collection box 88. The delivery speed of the wire electrode E and the tension applied to the wire electrode E are determined as processing conditions. The processing conditions are those specified by the processing condition data 122c, or, as described later, those adjusted by the adjustment unit 154.

[0048] The machining fluid supply control unit 186 controls the machining fluid supply device 106 to supply machining fluid to the electrode space between the wire electrode E and the workpiece W. The power supply control unit 188 controls the machining power supply 40 to apply voltage to the electrode space between the wire electrode E and the workpiece W.

[0049] The calculation unit 152 acquires the sensor signal transmitted from the signal processing circuit 116 of the signal processing device 110. Based on the detection result of the sensor 98x represented by the acquired sensor signal, the calculation unit 152 calculates the displacement of the line electrode E in the first crossing direction (X direction) relative to a reference position. The calculation of the reference position and the displacement relative to the reference position will use… Figure 4A , Figure 4B , Figure 4C This will be explained in detail later.

[0050] The calculation unit 152 calculates the displacement of the wire electrode E in the second crossing direction (Y direction) relative to a reference position based on the detection result of the sensor 98y represented by the acquired sensor signal. Such displacement of the wire electrode E may be caused by, for example, the discharge action or machining hydraulic pressure during electrical discharge machining.

[0051] The wire electrode E should ideally be at a reference position, but it may be displaced due to the discharge action or machining hydraulic pressure. For example, the wire electrode E may be closer to the workpiece W than the reference position, or it may be farther away from the workpiece W. Based on the displacement in the X and Y directions calculated by the calculation unit 152 and the machining position on the machining path, the positional relationship between the wire electrode E and the workpiece W is determined. That is, it can be determined whether the wire electrode E is closer to the workpiece W than the reference position, or farther away from the workpiece W than the reference position.

[0052] When the wire electrode E approaches the workpiece W, the machining amount increases; when the wire electrode E moves away from the workpiece W, the machining amount decreases. Therefore, when the wire electrode E is in a position different from the reference position, the machining amount may increase or decrease, resulting in a decrease in machining accuracy. To prevent this decrease in machining accuracy, the adjustment unit 154 adjusts the machining conditions or the machining path. The machining conditions are adjusted when the wire electrode E is in a position different from the reference position, or the machining path is adjusted to bring the wire electrode E to the reference position.

[0053] By adjusting the processing conditions, the target distance G, which is preset to be the distance between the wire electrode E and the workpiece W after processing, can be changed. Regarding the change of the target distance G, use... Figure 4B , Figure 4C This will be described in detail later. The adjustment unit 154 adjusts the machining conditions based on the displacement in the X and Y directions.

[0054] Based on the adjustment results of the adjustment unit 154, the machining control unit 150 performs electrical discharge machining on the workpiece W. As a result, the distance between the desired linear electrode E and the actual machined workpiece W is close to the adjusted target distance G.

[0055] For example, if the online electrode E is closer to the workpiece W than the reference position, the adjustment unit 154 can reduce the target distance G by an amount corresponding to the displacement in the X and Y directions by adjusting the processing conditions. This prevents excessive machining.

[0056] Furthermore, when the online electrode E is farther from the workpiece W than the reference position, the adjustment unit 154 can increase the target distance G by an amount corresponding to the displacement in the X and Y directions by adjusting the machining conditions. This prevents insufficient machining. Thus, it suppresses the reduction in machining accuracy.

[0057] As described above, the adjustment unit 154 adjusts the machining conditions based on the displacement in the X and Y directions. However, when the machining path is a straight line along the X direction, the adjustment unit 154 may also adjust the machining conditions based solely on the displacement in the Y direction based on the detection result of the sensor 98y. Similarly, when the machining path is a straight line along the X direction, the adjustment unit 154 may also adjust the machining conditions based solely on the displacement in the X direction based on the detection result of the sensor 98x.

[0058] As described above, the adjustment unit 154 can also change the machining path instead of changing the machining conditions. By adjusting the machining path away from the workpiece W using the adjustment unit 154, excessive machining can be prevented. By adjusting the machining path closer to the workpiece W using the adjustment unit 154, insufficient machining can be prevented. In this way, a decrease in machining accuracy can be suppressed.

[0059] Figure 4A , Figure 4B and Figure 4C These are diagrams illustrating the detection results of sensor 98y corresponding to the displacement of the position Pe of the wire electrode E during machining. In the examples shown in these diagrams, the wire electrode E moves relative to the workpiece W along a machining path that is linear in the positive X direction. While moving relative to the workpiece W, the wire electrode E performs electrical discharge machining on the workpiece W, which is positioned in the positive Y direction.

[0060] exist Figure 4A In the process, the position Pe of the wire electrode E during machining is at the reference position Pr. The reference position Pr is the position Pe of the wire electrode E, supported by the first wire guide 64 and the second wire guide 66 located along the direction of gravity, when the workpiece W is not being machined. Figure 4A In the example shown, during the machining process of the workpiece W, the position Pe of the wire electrode E does not shift from the reference position Pr.

[0061] When the position Pe of the line electrode E does not shift from the reference position Pr, a portion of the light L projected from the projection fiber 98yt of the sensor 98y is blocked by the line electrode E. As a result, the amount of light L received by the light-receiving fiber 98yr at the receiving end of the sensor 98y corresponds to a state where the displacement of the position Pe of the line electrode E is zero. That is, the displacement of 0 can be easily derived from the amount of light received, As.

[0062] The wire electrode E, without displacement from the reference position Pr, processes the workpiece W along the processing path specified by the processing program 122r under the processing conditions specified in the processing condition data 122c. According to these processing conditions, the target distance G is the value Gs. In this case, as... Figure 4A As shown, the processed surface Sp of the processed object W is formed at a position Gs that is equal to the distance G from the reference position Pr to the target.

[0063] When the machining surface Si currently being machined and the predetermined machining surface Su to be machined in the future are machined by the wire electrode E, they are also formed at a position Gs that is equal to the distance G from the reference position Pr.

[0064] exist Figure 4B In the process, the position Pe of the wire electrode E during machining is located at a traveling position Pc that is closer to the workpiece W than the reference position Pr. The offset D of the position Pe of the wire electrode E relative to the reference position Pr is calculated as the displacement of the position Pe of the wire electrode E. That is, in Figure 4B In the example shown, the displacement in the second intersection direction, i.e., the Y direction, is the offset D.

[0065] When the position Pe of the line electrode E is displaced by an offset D from the reference position Pr, a portion of the light L projected from the projection fiber 98yt of the sensor 98y is blocked by the line electrode E. As a result, the amount of light Ac received by the light-receiving fiber 98yr of the sensor 98y at the receiving end corresponds to the state where the position Pe of the line electrode E approaches the workpiece W by the aforementioned displacement. Since the amount of light Ac is greater than the amount of light As when the displacement is zero, it can be determined that the position Pe of the line electrode E is close to the workpiece W.

[0066] That is, based on the amount of light received Ac, it is easy to deduce the case where the position Pe of the line electrode E is close to the workpiece W and the case where the displacement is the offset D.

[0067] Since the position Pe of the wire electrode E is closer to the workpiece W than the reference position Pr, it is necessary to reduce the target distance G as the displacement amount of the offset D. Therefore, the adjustment unit 154 adjusts the processing conditions determined in the processing condition data 122c to reduce the processing amount. According to the adjusted processing conditions, the target distance G becomes a value Gc that is smaller than the displacement amount of the offset D compared to the value Gs.

[0068] In this case, such as Figure 4B As shown, the machined surface Sp of the processed object W is formed at a position Gc, which is equal to the distance G from the travel position Pc. The position of the machined surface Sp is also the position Gs, which is the distance G from the reference position Pr before the change in distance G from the target.

[0069] If processing is performed while maintaining the value Gs without changing the target distance G, the processed surface Sc of the processed object W is formed at a position away from the value Gs from the travel position Pc. That is, the processing amount becomes excessive. However, by adjusting the processing conditions to change the target distance G to the value Gc, excessive processing can be prevented.

[0070] When the machining surface Si currently being machined and the predetermined machining surface Su to be machined in the future are machined by the wire electrode E, they are also formed at a position Gc that is equal to the distance G from the target from the traveling position Pc.

[0071] Additionally, as described above, the adjustment unit 154 can also adjust the machining path specified by the machining program 122r. Figure 4B In the example shown, the adjustment unit 154 causes the machining path to move away from the workpiece W by an offset amount D. As a result, the position Pe of the wire electrode E during machining moves from the current traveling position Pc towards the reference position Pr (see reference). Figure 4A ).like Figure 4A As shown, the processed surface Sp of the processed object W is formed at a position Gs that is equal to the distance G from the reference position Pr to the target.

[0072] exist Figure 4C In the process, the position Pe of the wire electrode E during machining is located at a traveling position Pa that is farther away from the workpiece W than the reference position Pr. The offset D of the position Pe of the wire electrode E relative to the reference position Pr is calculated as the displacement of the position Pe of the wire electrode E. That is, in Figure 4C In the example shown, the displacement in the second intersection direction, i.e., the Y direction, is the offset D.

[0073] When the position Pe of the line electrode E is displaced by an offset D from the reference position Pr, a portion of the light L projected from the projection fiber 98yt of the sensor 98y is blocked by the line electrode E. As a result, the amount of light Aa received by the light-receiving fiber 98yr of the sensor 98y at the receiving end corresponds to the state where the position Pe of the line electrode E has moved away from the workpiece W by the aforementioned displacement. Since the amount of light received Aa is less than the amount of light received As when the displacement is zero, it can be determined that the position Pe of the line electrode E has moved away from the workpiece W.

[0074] That is, based on the amount of light received Aa, it is easy to deduce the case where the position Pe of the wire electrode E is away from the workpiece W and the case where the displacement is the offset D.

[0075] Since the position Pe of the wire electrode E is farther from the workpiece W than the reference position Pr, the target distance G needs to be increased as the displacement amount of the offset D. Therefore, the adjustment unit 154 adjusts the processing conditions determined in the processing condition data 122c to increase the processing amount. According to the adjusted processing conditions, the target distance G becomes a value Ga that is larger than the displacement amount of the offset D by the ratio Gs.

[0076] At this time, as Figure 4C As shown, the machined surface Sp of the processed object W is formed at a position Ga, which is equal to the target distance G, from the traveling position Pa. The position of the machined surface Sp is also the position Gs, which is the original value of the distance G from the reference position Pr to the target distance G.

[0077] If processing is performed while maintaining the value Gs without changing the target distance G, the processed surface Sa of the processed object W will be formed at the position where it departs from the travel position Pa and leaves the value Gs. That is, the processing amount becomes too small. However, by adjusting the processing conditions to change the target distance G to the value Ga, it is possible to prevent the processing amount from being too small.

[0078] When the machining surface Si currently being machined and the predetermined machining surface Su to be machined in the future are machined by the wire electrode E, they are also formed at a position Ga that is equal to the target distance G from the traveling position Pa.

[0079] Additionally, as described above, the adjustment unit 154 can also adjust the machining path specified by the machining program 122r. Figure 4C In the example shown, the adjustment unit 154 moves the machining path closer to the workpiece W by a displacement amount D. As a result, the position Pe of the wire electrode E during machining moves from the current traveling position Pa to the reference position Pr (see reference). Figure 4A ).like Figure 4A As shown, the processed surface Sp of the processed object W is formed at a position Gs that is equal to the distance G from the reference position Pr to the target.

[0080] As described above, based on the actual position Pe of the wire electrode E detected by the sensor 98y, the offset D of the position Pe of the wire electrode E relative to the reference position Pr is calculated as the displacement of the position Pe of the wire electrode E. Therefore, even if the actual machining shape differs from the machining shape represented by the machining path information determined by the machining program 122r, the machining conditions or machining path can be adjusted to suppress the reduction in machining accuracy.

[0081] In use Figure 4A , Figure 4B and Figure 4C In the above explanation, since the machining path is a straight line in the X direction, the detection result of sensor 98y is used. When the machining path is a straight line in the Y direction, the detection result of sensor 98x is used in the same way as described above. When the machining path is a two-dimensional shape (e.g., a curved shape with corners, etc.), the detection results of sensors 98x and 98y are used in the same way as described above. Therefore, it is possible to calculate the displacement of the position Pe of the line electrode E moving in various machining paths during machining.

[0082] In addition, Figure 4B , Figure 4C In the example shown, the machining conditions or machining path are adjusted when the displacement (offset D) of the position Pe of the online electrode E is greater than zero. However, the machining conditions or machining path can also be adjusted when the displacement is greater than a non-zero threshold. This threshold is determined based on the machining path, machining shape, or required accuracy, etc.

[0083] As described above, the adjustment unit 154 changes the machining amount by adjusting the machining conditions or machining path. Regarding the change in machining amount caused by the adjustment of machining conditions, the following is used... Figure 5 This will be described later. Adjusting the machining path to approach the workpiece W increases the machining quantity. Adjusting the machining path to move away from the workpiece W decreases the machining quantity.

[0084] Figure 5 This is a diagram illustrating the process performed as an adjustment of processing conditions. Processing conditions include, for example, processing speed, discharge power, inter-electrode voltage, voltage application time, and / or voltage application stop time.

[0085] The processing speed is the speed at which the wire electrode E and the workpiece W move relative to each other during processing, driven by the worktable drive unit 102 to the worktable 62.

[0086] The discharge power is the power generated between the line electrode E, which is energized by the machining power supply 40, and the workpiece W. The applied voltage between the electrodes is the voltage applied by the machining power supply 40 to the electrodes. The voltage application time is the duration during which the machining power supply 40 applies a pulsed voltage to the electrodes. The voltage application stop time is the time during which the voltage application stops when the machining power supply 40 applies a pulsed voltage to the electrodes.

[0087] The wire electrode delivery speed is the delivery speed at which the wire electrode E is delivered by the electrode delivery drive unit 104. The wire electrode tension is the tension applied to the wire electrode E delivered by the electrode delivery drive unit 104.

[0088] The processing fluid flow rate is the amount of processing fluid supplied from the processing fluid supply device 106 to the electrode space between the linear electrode E and the workpiece W.

[0089] When the machining speed, which is a machining condition, is adjusted by the adjustment unit 154, the machining quantity can be increased by decreasing the machining speed, and the machining quantity can be decreased by increasing the machining speed. The worktable drive control unit 182 of the machining control unit 150 controls the worktable drive unit 102 to move the worktable 62 according to the machining speed adjusted by the adjustment unit 154.

[0090] When the discharge power, which is a processing condition, is adjusted by the adjustment unit 154, the processing amount can be increased by increasing the discharge power and decreased by decreasing the discharge power. The power control unit 188 of the processing control unit 150 controls the processing power supply 40 according to the discharge power adjusted by the adjustment unit 154, so that a discharge occurs between the wire electrode E and the workpiece W.

[0091] When the inter-electrode voltage, which serves as a machining condition, is adjusted by the adjustment unit 154, the machining amount can be increased by increasing the inter-electrode voltage, and the machining amount can be reduced by decreasing the inter-electrode voltage. The power control unit 188 of the machining control unit 150 controls the machining power supply 40 to apply a voltage between the wire electrode E and the workpiece W based on the inter-electrode voltage adjusted by the adjustment unit 154.

[0092] When the voltage application time, which is a processing condition, is adjusted by the adjustment unit 154, the processing amount can be increased by increasing the voltage application time, and the processing amount can be reduced by decreasing the voltage application time. The power control unit 188 of the processing control unit 150 controls the processing power supply 40 to apply voltage between the wire electrode E and the workpiece W according to the voltage application time adjusted by the adjustment unit 154.

[0093] When the voltage application stop time, which is a processing condition, is adjusted by the adjustment unit 154, the processing amount can be increased by reducing the voltage application stop time, and the processing amount can be reduced by increasing the voltage application stop time. The power control unit 188 of the processing control unit 150 controls the processing power supply 40 to apply voltage between the wire electrode E and the workpiece W according to the voltage application stop time adjusted by the adjustment unit 154.

[0094] The user of the wire electrical discharge machining (EDM) machine 10 inputs an instruction to start the EDM of the workpiece W into the control unit 30. The machining control unit 150 retrieves the machining program 122r and machining condition data 122c from the storage unit 122. Then, the machining begins... Figure 6 The processing order is shown. Figure 6 This is a flowchart illustrating an example of the processing sequence in a wire electrical discharge machining (WEDM) method. This processing sequence is, for example, performed by the arithmetic unit 120 of the control device 30.

[0095] When this processing sequence begins, electrical discharge machining (EDM) is initiated on the workpiece W. In step S1, the electrode delivery control unit 184 of the machining control unit 150 controls the electrode delivery drive unit 104 to deliver the wire electrode E. In step S2, the table drive control unit 182 of the machining control unit 150 controls the table drive unit 102 to move the table 62. In step S3, the power control unit 188 of the machining control unit 150 controls the machining power supply 40 to apply a voltage between the wire electrode E and the workpiece W.

[0096] In step S4, during the processing of the workpiece W, the calculation unit 152 acquires sensor signals representing the detection results of sensors 98x and 98y from the signal processing device 110. In step S5, the calculation unit 152 calculates the displacement of the position Pe of the line electrode E relative to the reference position Pr based on the detection results of sensors 98x and 98y.

[0097] In step S6, the adjustment unit 154 determines whether the displacement of the position Pe of the wire electrode E is greater than a threshold. If the result is "yes" in step S6, the process proceeds to step S7. If the result is "no" in step S6, the process proceeds to step S8. In step S7, the adjustment unit 154 adjusts the processing conditions or processing path during the processing of the workpiece W.

[0098] In step S8, the machining control unit 150 determines whether the electrical discharge machining of the workpiece W has ended. If the result in step S8 is "yes", the process proceeds to step S9. If the result in step S8 is "no", the process returns to step S1.

[0099] In step S9, the power control unit 188 of the machining control unit 150 controls the machining power supply 40 to stop applying voltage between the wire electrode E and the workpiece W. In step S10, the table drive control unit 182 of the machining control unit 150 controls the table drive unit 102 to stop the movement of the table 62. In step S11, the electrode delivery control unit 184 of the machining control unit 150 controls the electrode delivery drive unit 104 to stop the delivery of the wire electrode E. When the processing in step S11 is completed, this processing sequence ends.

[0100] According to this embodiment, the displacement of the position Pe of the wire electrode E is calculated based on the detection results of the sensors 98x and 98y provided on the first wire guide 64. The machining conditions or machining path are adjusted based on this displacement. Based on this adjustment, the workpiece W moves relative to the wire electrode E, and a discharge is generated between the workpiece W and the wire electrode E. Therefore, the reduction in machining accuracy caused by the displacement of the wire electrode E during electrical discharge machining can be suppressed.

[0101] In this embodiment, sensors 98x and 98y are fiber optic sensors. However, other sensors can be used instead of fiber optic sensors. Other sensors include, for example, optical sensors, proximity sensors (eddy current displacement sensors), contact sensors, ultrasonic sensors, image sensors, etc. These sensors can be integrated with the signal processing device 110.

[0102] When using a light sensor, the change in the amount of reflected light or blocked light generated when light is emitted towards the line electrode E can be used to calculate the displacement of the line electrode E. When using a proximity sensor, the change in impedance caused by the eddy currents generated by the line electrode E can be used to calculate the displacement of the line electrode E.

[0103] When using a contact sensor, the displacement obtained by the contact sensor in contact with the line electrode E can be used to calculate the displacement of the line electrode E. When using an ultrasonic sensor, the change in the ultrasonic wave reflected by the line electrode E can be used to calculate the displacement of the line electrode E. When using an image sensor, the displacement of the line electrode E within the image can be used to calculate the displacement of the line electrode E.

[0104] The above-described embodiments can also be modified as follows. In the following modifications, descriptions that are repeated in the embodiments are omitted.

[0105] (Modified Example)

[0106] In the above embodiment, the adjustment unit 154 can change the machining amount by adjusting the machining conditions. These machining conditions include, for example, adjusting the machining speed, discharge power, inter-electrode voltage, voltage application time, and / or voltage application stop time. By changing the machining amount, a decrease in machining accuracy can be suppressed.

[0107] Regarding the workpiece W, the requirements for machining speed, machining volume, surface roughness, and machining accuracy differ depending on whether roughing or finishing is being performed. To meet various requirements simultaneously, beyond just machining accuracy, other machining conditions need to be adjusted in addition to those exemplified above. These other machining conditions include, for example, the wire electrode feed rate, wire electrode tension, and / or machining fluid flow rate.

[0108] When the wire electrode feed speed, which is a processing condition, is adjusted by the adjustment unit 154, the discharge frequency can be increased by increasing the wire electrode feed speed, and the discharge frequency can be decreased by decreasing the wire electrode feed speed. The electrode feed control unit 184 of the processing control unit 150 controls the electrode feed drive unit 104 to rotate the roller 82 according to the wire electrode feed speed adjusted by the adjustment unit 154, thereby feeding out the wire electrode E.

[0109] By changing the discharge frequency according to the displacement of the line electrode E (Pe), all the above requirements can be met simultaneously.

[0110] When the wire electrode tension, which is a processing condition, is adjusted by the adjustment unit 154, the vibration of the wire electrode E can be reduced by increasing the wire electrode tension, and the risk of wire electrode breakage can be reduced by decreasing the wire electrode tension. The electrode feed control unit 184 of the processing control unit 150 controls the electrode feed drive unit 104 to rotate the roller 82, the pinch roller 84 and the feed roller 86 according to the wire electrode tension adjusted by the adjustment unit 154, thereby applying tension to the wire electrode E.

[0111] When the vibration of the wire electrode E decreases, the displacement of the position Pe of the wire electrode E decreases. Therefore, it is possible to suppress the reduction in machining accuracy. However, the machining volume may decrease. Additionally, the risk of wire electrode E breaking increases. Therefore, for example, during finishing, by adjusting the wire electrode tension according to the displacement of the position Pe of the wire electrode E, it is possible to simultaneously meet all the above requirements.

[0112] When the flow rate of the machining fluid, which is a machining condition, is adjusted by the adjustment unit 154, the influence of the machining fluid on the wire electrode E increases by increasing the flow rate. Therefore, the machining accuracy may decrease. However, since waste residue is easily removed by the machining fluid, the decrease in machining accuracy can be suppressed, and the machining speed can be increased. For example, by increasing the flow rate of the machining fluid during rough machining, the requirements related to the machining speed can be met with particular priority.

[0113] Reducing the machining fluid flow rate makes it difficult to remove waste residue, which may lead to short circuits between electrodes. In this case, machining accuracy may decrease. However, the influence of the machining fluid on the wire electrode E is reduced. Therefore, the decrease in machining accuracy can be suppressed. For example, by appropriately reducing the machining fluid flow rate during finishing, it is possible to prioritize meeting the requirements related to machining accuracy.

[0114] The machining fluid supply control unit 186 of the machining control unit 150 controls the machining fluid supply device 106 to supply machining fluid to the electrode space between the wire electrode E and the workpiece W, based on the machining fluid flow rate adjusted by the adjustment unit 154. By adjusting the machining fluid flow rate according to the displacement of the position Pe of the wire electrode E, all the above-mentioned requirements can be met simultaneously.

[0115] According to this modified example, the wire electrode feed rate, wire electrode tension, and / or machining fluid flow rate are adjusted as machining conditions. Therefore, various requirements such as machining speed, machining volume, surface roughness, and machining accuracy can be met simultaneously.

[0116] The following notes are also disclosed regarding the above-described embodiments and variations.

[0117] (Postscript 1)

[0118] The wire electrical discharge machining (EDM) machine 10 disclosed herein moves a wire electrode E along a machining path relative to a workpiece W, and generates a discharge between the workpiece and the wire electrode according to machining conditions, thereby machining the workpiece. The wire EDM machine includes: a first wire guide 64 supporting the wire electrode below the workpiece; a second wire guide 66 supporting the wire electrode above the workpiece; sensors 98x and 98y disposed on at least one of the first and second wire guides, detecting the wire electrode along intersecting directions X and Y that intersect the feed direction Z of the wire electrode; a calculation unit 152 calculating the displacement of the position Pe of the wire electrode in the intersecting directions based on the detection results of the sensors; and an adjustment unit 154 adjusting the machining conditions or the machining path based on the displacement.

[0119] (Postscript 2)

[0120] In the wire electrical discharge machining machine described in Appendix 1, the calculation unit calculates the offset D of the position of the wire electrode relative to the reference position as the displacement amount, using the position of the wire electrode supported by the first wire guide and the second wire guide located along the direction of gravity as the reference position Pr when the workpiece is not being processed.

[0121] (Note 3)

[0122] In the wire electrical discharge machining machine described in Appendix 2, when the wire electrode is closer to the workpiece than the reference position, the adjustment unit adjusts the machining conditions to reduce the displacement amount by a target distance G, which is preset as the distance between the wire electrode and the workpiece after machining, or adjusts the machining path to move away from the workpiece by the displacement amount. When the wire electrode is farther away from the workpiece than the reference position, the adjustment unit adjusts the machining conditions to increase the displacement amount by the target distance, or adjusts the machining path to move closer to the workpiece by the displacement amount.

[0123] (Note 4)

[0124] In any one of the appendices 1 to 3, the wire electrical discharge machine is provided with two sensors. One of the two sensors detects the wire electrode along a first intersecting direction X that intersects the feed direction, and the other sensor may also detect the wire electrode along a second intersecting direction Y that intersects the feed direction and is orthogonal to the first intersecting direction.

[0125] (Note 5)

[0126] In any one of the appendices 1 to 4, the sensor is an optical fiber sensor, which has a light-emitting fiber 98xt, 98yt that projects light L from the light source 112, and a light-receiving fiber 98xr, 98yr that receives the light projected by the light-emitting fiber. The calculation unit calculates the displacement based on the amount of light received by the light-receiving fiber As, Ac, Aa.

[0127] (Note 6)

[0128] The wire electrical discharge machining method disclosed herein is performed by a wire electrical discharge machining machine, which includes: a first wire guide that supports a wire electrode below a workpiece; a second wire guide that supports the wire electrode above the workpiece; and a sensor disposed on at least one of the first and second wire guides, which detects the wire electrode along a cross direction intersecting the delivery direction of the wire electrode. The wire electrical discharge machining machine moves the wire electrode relative to the workpiece along a machining path and generates a discharge between the workpiece and the wire electrode according to machining conditions, thereby machining the workpiece. The wire electrical discharge machining method includes: a calculation step of calculating the displacement of the position of the wire electrode in the cross direction based on the detection result of the sensor; and an adjustment step of adjusting the machining conditions or the machining path according to the displacement.

[0129] (Note 7)

[0130] In the wire electrical discharge machining method described in Appendix 6, in the calculation step, the position of the wire electrode supported by the first wire guide and the second wire guide located along the direction of gravity is used as a reference position in the state where the workpiece is not being machined, and the offset of the position of the wire electrode relative to the reference position is calculated as the displacement.

[0131] (Postscript 8)

[0132] In the wire electrical discharge machining method described in Appendix 7, during the adjustment step, when the wire electrode is closer to the workpiece than the reference position, the target distance G, which is preset to be the distance between the wire electrode and the workpiece after machining, is reduced by adjusting the machining conditions, or the machining path is adjusted to move away from the workpiece by the displacement amount. When the wire electrode is farther from the workpiece than the reference position, the target distance is increased by adjusting the machining conditions, or the machining path is adjusted to move closer to the workpiece by the displacement amount.

[0133] (Note 9)

[0134] In any one of the line discharge machining methods in Appendices 6 to 8, the sensor is an optical fiber sensor having a light-emitting optical fiber that projects light from a light source and a light-receiving optical fiber that receives the light projected by the light-emitting optical fiber. In the calculation step, the displacement is calculated based on the amount of light received by the light-receiving optical fiber.

[0135] This disclosure has been described in detail, but it is not limited to the various embodiments described above. Various additions, substitutions, modifications, and partial deletions can be made to these embodiments without departing from the spirit of this disclosure, or from the spirit of this disclosure derived from the claims and their equivalents. Furthermore, these embodiments can also be implemented in combination. For example, in the above embodiments, the order of each action and each process is shown as an example, and is not limited thereto. The same applies to the use of numerical values ​​or mathematical formulas in the description of the above embodiments.

[0136] Symbol Explanation

[0137] 10… wire EDM machine 20… main body

[0138] 30…Control device 40…Processing power supply

[0139] 62… Workbench 64… First wire guide

[0140] 66…Second guide wire device 68…First guide block

[0141] 70…First guide wheel 72…First nozzle

[0142] 74…Second guide block 76…Second guide wheel

[0143] 78… Nozzle 2 80… Winding tube

[0144] 82…roller 84…pinch roll

[0145] 86…feed roller 88…recovery box

[0146] 90…machining groove 92…base

[0147] 98… Sensor holding unit 102… Table drive unit

[0148] 104…Electrode delivery drive unit 106…Processing fluid supply device

[0149] 110…Signal processing device 112…Light source

[0150] 114…Light receiving element 116…Signal processing circuit

[0151] 120…Arithmetic Unit 122…Storage Unit

[0152] 150…Machining Control Department 152…Calculation Department

[0153] 154…Adjustment section 182…Workbench drive control section

[0154] 184…Electrode delivery control unit 186…Processing fluid supply control unit

[0155] 188…Power Control Department.

Claims

1. A wire electrical discharge machining (EDM) machine that moves a wire electrode along a machining path relative to a workpiece and, according to machining conditions, generates a discharge between the workpiece and the wire electrode to machine the workpiece. The wire electrical discharge machining machine is characterized by having: The first wire guide supports the wire electrode below the workpiece. The second wire guide supports the wire electrode above the workpiece. A sensor, disposed on at least one of the first wire guide and the second wire guide, detects the wire electrode along a cross direction that intersects the delivery direction of the wire electrode. The calculation unit calculates the displacement of the line electrode in the crossing direction based on the detection results of the sensor. as well as The adjustment unit adjusts the processing conditions or the processing path based on the displacement.

2. The wire electrical discharge machining machine according to claim 1, characterized in that, The calculation unit will use the position of the wire electrode supported by the first wire guide and the second wire guide, which are located along the direction of gravity, as a reference position Pr when the workpiece is not being processed, and calculate the offset of the position of the wire electrode relative to the reference position as the displacement.

3. The wire electrical discharge machining machine according to claim 2, characterized in that, When the line electrode is closer to the workpiece than the reference position, the adjustment unit adjusts the processing conditions to reduce the displacement by a target distance that is preset as the distance between the line electrode and the workpiece after processing, or adjusts the processing path to move away from the workpiece by the displacement. When the line electrode is farther away from the workpiece than the reference position, the adjustment unit adjusts the processing conditions to increase the displacement by a target distance, or adjusts the processing path to move closer to the workpiece by the displacement.

4. The wire electrical discharge machining machine according to any one of claims 1 to 3, characterized in that, Set up two of the aforementioned sensors. One of the two sensors detects the line electrode along a first intersecting direction that intersects the delivery direction, and the other sensor detects the line electrode along a second intersecting direction that intersects the delivery direction and is orthogonal to the first intersecting direction.

5. The wire electrical discharge machining machine according to any one of claims 1 to 4, characterized in that, The sensor is an optical fiber sensor, which has a light-emitting optical fiber that projects light from a light source and a light-receiving optical fiber that receives the light projected by the light-emitting optical fiber. The calculation unit calculates the displacement based on the amount of light received by the light-receiving optical fiber.

6. A wire electrical discharge machining method, performed by a wire electrical discharge machining machine, characterized in that... The wire electrical discharge machining (EDM) machine includes: a first wire guide that supports a wire electrode below a workpiece; a second wire guide that supports the wire electrode above the workpiece; and a sensor disposed on at least one of the first and second wire guides, which detects the wire electrode in a cross direction intersecting the delivery direction of the wire electrode. The EDM machine moves the wire electrode relative to the workpiece along a machining path and generates a discharge between the workpiece and the wire electrode according to machining conditions, thereby machining the workpiece. The wire electrical discharge machining method includes: The calculation steps involve calculating the displacement of the line electrode in the intersecting direction based on the sensor's detection results; and The adjustment steps involve adjusting the processing conditions or the processing path based on the displacement amount.

7. The wire electrical discharge machining method according to claim 6, characterized in that, In the calculation step, the position of the wire electrode supported by the first wire guide and the second wire guide, which are located along the direction of gravity, is used as a reference position in the unprocessed state of the workpiece, and the offset of the position of the wire electrode relative to the reference position is calculated as the displacement.

8. The wire electrical discharge machining method according to claim 7, characterized in that, In the adjustment step, when the wire electrode is closer to the workpiece than the reference position, the processing conditions are adjusted to reduce the target distance between the wire electrode and the workpiece after processing by the displacement amount, or the processing path is adjusted to move away from the workpiece by the displacement amount. When the wire electrode is farther from the workpiece than the reference position, the processing conditions are adjusted to increase the target distance by the displacement amount, or the processing path is adjusted to move closer to the workpiece by the displacement amount.

9. The wire electrical discharge machining method according to any one of claims 6 to 8, characterized in that, The sensor is an optical fiber sensor, which has a light-emitting optical fiber that projects light from a light source and a light-receiving optical fiber that receives the light projected by the light-emitting optical fiber. In the calculation step, the displacement is calculated based on the amount of light received by the light-receiving optical fiber.

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