Wire electric discharge machining device and wire electric discharge machining method

Abstract

A wire electric discharge machining device (100) has a moving device (3), a control section, a machining tank (6) that houses a workpiece (W) and stores a machining liquid (10), and a container (9) that is disposed above the workpiece (W) and has a capacity capable of covering the workpiece (W), and has an opening only toward the bottom surface of the workpiece (W). The container (9) is capable of changing to a first state in which a side surface (9c) is contracted, an opening (9a) and an upper surface (9b) are located below a liquid surface (10a) of the machining liquid (10) of the machining tank (6), and a second state in which the side surface (9c) is elongated, the opening (9a) is located below the liquid surface (10a), and the upper surface (9b) is located above the liquid surface (10a). By changing the container (9) from the first state to the second state, the machining liquid (10) is filled in the inside of the container (9) up to a position higher than the liquid surface (10a). The workpiece (W) is capable of entering the inside of the container (9) in the second state as the electric discharge machining advances.

Description

Technical Field

[0001] This invention relates to a wire discharge machining apparatus and a wire discharge machining method for performing electrical discharge machining on a workpiece by generating a discharge between an online electrode and the workpiece. Background Technology

[0002] Previously, wire electrical discharge machining (EDM) apparatuses were known that generated a discharge by applying a voltage between a wire electrode and a workpiece, thereby melting the workpiece and performing EDM on it.

[0003] As disclosed in Patent Document 1, a typical wire EDM apparatus has a processing tank containing an insulating processing fluid. In this processing fluid, a discharge is generated between the wire electrode and the workpiece to perform EDM. The rationale for performing EDM in this way is to achieve effects such as cooling of the wire electrode and the workpiece, fire prevention, and removal of processing debris generated during EDM. By performing EDM on the workpiece, a processing groove is formed on it.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2014-656 Summary of the Invention

[0005] In electrical discharge machining (EDM) where the workpiece is moved upwards from below relative to a wire electrode, the machining tank becomes higher than the wire electrode as the EDM progresses. If the EDM continues, the machining tank becomes higher than the surface of the machining fluid, and the surface tension of the remaining machining fluid in the machining tank exerts a force in the direction where the machining tank narrows. Therefore, a problem arises where, if the workpiece is thin and lacks sufficient rigidity, it deforms, leading to a narrowing of the machining tank. If the machining tank is narrow, it becomes difficult to remove machining chips through the flow of the machining fluid, resulting in abnormal discharges, wire electrode breakage, etc., leading to reduced workpiece quality and lower workpiece productivity.

[0006] As a solution to the above problems, one proposed method is to make the machining tank sufficiently deep and raise the water level of the machining fluid so that the workpiece can be electrically processed while completely immersed in the machining fluid. However, when the workpiece is moved from bottom to top relative to the wire electrode for electrical discharge machining, the wire electrode is positioned to contact the upper end of the workpiece at the start of the machining process, but is located at the lower end of the workpiece at the end of the machining process. Therefore, this method requires the depth of the machining tank to be greater than or equal to twice the height of the workpiece, resulting in a large overall size of the wire electrical discharge machining apparatus.

[0007] As another solution to the aforementioned problem, a method for electrical discharge machining (EDM) is conceived, as disclosed in Patent Document 1, in which the workpiece is moved from top to bottom relative to a wire electrode. In this method, the machining tank formed on the workpiece during EDM is sequentially immersed in the machining fluid, thus effectively solving the aforementioned problem. However, in this method, the machining fluid vaporizes due to the heat of the discharge, and the bubbles generated by this vaporization tend to accumulate in the machining tank where the discharge occurs, thus posing a risk of instability in the EDM process.

[0008] The present invention was made in view of the above circumstances, and its object is to provide a wire electrical discharge machining apparatus that can suppress the overall enlargement of the wire electrical discharge machining apparatus even when the workpiece is moved from below to above relative to the wire electrode for electrical discharge machining, and can perform electrical discharge machining on the workpiece while the workpiece is completely immersed in the machining fluid.

[0009] To address the aforementioned issues and achieve the objectives, the present invention relates to a wire electrical discharge machining (EDM) apparatus that generates a discharge between a wire electrode and a workpiece to perform EDM on the workpiece. This wire EDM apparatus includes: a moving device that moves the wire electrode and the workpiece relative to each other; and a control unit that controls the moving device. Furthermore, the wire EDM apparatus of the present invention includes: a machining tank that contains the workpiece and stores a machining fluid; and a container disposed above the workpiece and having a capacity capable of covering the workpiece, having an opening only facing the bottom surface of the workpiece. The container has an upper surface disposed above the opening on the bottom surface, separate from the opening, and side surfaces extending from the upper surface to the opening and formed in a manner that allows free expansion and contraction in the vertical direction. The container can be changed to a first state and a second state. The first state is characterized by side contraction, with the opening and upper surface below the surface of the machining fluid in the machining tank; the second state is characterized by side extension, with the opening below the surface of the machining fluid in the machining tank and the upper surface above the surface of the machining fluid in the machining tank. By changing the container from state 1 to state 2, the container is filled with processing fluid up to the level of the processing fluid in the processing tank. The workpiece can then enter the container in state 2 as the electrical discharge machining progresses.

[0010] The effects of the invention

[0011] The wire electrical discharge machining apparatus of the present invention achieves the following effects: even when the workpiece is moved from below to above relative to the wire electrode and electrical discharge machining is performed on the workpiece, the overall size of the wire electrical discharge machining apparatus can be suppressed, and the workpiece can be electrically processed while the entire workpiece is immersed in the processing fluid. Attached Figure Description

[0012] Figure 1 This is a perspective view showing the main parts of the wire electrical discharge machining apparatus according to Embodiment 1.

[0013] Figure 2 This is a front view showing the process of filling the container with processing fluid according to Embodiment 1, and a diagram showing the state of the container's side contraction.

[0014] Figure 3 This is a front view showing the process of filling the container with processing fluid in Embodiment 1, and a diagram showing the state of the container's side extension.

[0015] Figure 4 This is a flowchart illustrating the process of a wire electrical discharge machining method performed by the wire electrical discharge machining apparatus according to Embodiment 1.

[0016] Figure 5 This is a front view showing the container, wire electrode, and the area around the workpiece during the electrical discharge machining process in Embodiment 1.

[0017] Figure 6 It is along Figure 5 The cross-sectional view along line VI-VI shown is a diagram of the wire electrode and the area around the workpiece during the electrical discharge machining process in Embodiment 1.

[0018] Figure 7 This is a front view showing the container, wire electrode, and workpiece surrounding the electrical discharge machining process in Embodiment 1, and a diagram showing the state in which bubbles are generated inside the container.

[0019] Figure 8 This is a front view showing the container, wire electrode, and workpiece surrounding the completed electrical discharge machining in Embodiment 1, and a diagram showing the state of a gas layer generated inside the container.

[0020] Figure 9 This is a front view showing the container, wire electrode, and workpiece surrounding the electrical discharge machining process in a modified example of Embodiment 1, and a diagram showing the state in which bubbles are generated inside the container.

[0021] Figure 10 This is a front view showing the container, wire electrode, and workpiece surrounding the completed electrical discharge machining in a modified example of Embodiment 1. It is also a diagram showing the state of a gas layer generated inside the container.

[0022] Figure 11 This is a front view showing the container, wire electrode, and workpiece surrounding the wire discharge machining apparatus according to Embodiment 2 during the discharge machining process, and a diagram showing the state of bubbles and gas layers generated inside the container.

[0023] Figure 12This is a front view showing the container, wire electrode, and workpiece surrounding the wire electrical discharge machining apparatus according to Embodiment 2, and a diagram showing the state of venting the gas remaining inside the container.

[0024] Figure 13 This is a flowchart illustrating the process of a wire electrical discharge machining method performed by the wire electrical discharge machining apparatus according to Embodiment 2.

[0025] Figure 14 This is a front view of the wire electrical discharge machining apparatus according to Embodiment 3.

[0026] Figure 15 This is a front view of the wire electrical discharge machining apparatus according to Embodiment 3, and a diagram showing the state in which bubbles generated inside the container are discharged. Detailed Implementation

[0027] The wire discharge machining apparatus and wire discharge machining method according to the embodiments will now be described in detail based on the accompanying drawings.

[0028] Implementation Method 1

[0029] Figure 1 This is a perspective view showing the main parts of the wire electrical discharge machining (EDM) apparatus 100 according to Embodiment 1. The EDM apparatus 100 is a device that generates a discharge between a wire electrode 2 and a workpiece W, performing EDM machining on the workpiece W. The EDM apparatus 100 cuts the workpiece W into multiple plate-shaped components. Figure 1 The X, Y, and Z axes of a 3-axis Cartesian coordinate system are shown. The X-axis direction is the same as the travel direction of the wire electrode 2 on the workpiece W, that is, the wire electrode 2 is in the same direction of travel relative to the workpiece W disposed in the wire electrical discharge machining apparatus 100. Figure 1 Arrow 101 indicates the travel direction of the wire electrode 2 on the workpiece W. The Y-axis direction is parallel to the direction in which the wire electrode 2 is parallel to the workpiece W disposed in the wire electrical discharge machining apparatus 100. The Z-axis direction is parallel to the height direction of the wire electrical discharge machining apparatus 100. The height direction of the wire electrical discharge machining apparatus 100 is parallel to the vertical direction.

[0030] The wire electrical discharge machining (EDM) apparatus 100 includes multiple guide rollers 1, wire electrodes 2, a moving device 3, a power supply unit 4, and a control unit 5. Additionally, the EDM apparatus 100 includes a machining tank 6, a machining fluid tank 7, a machining fluid nozzle 8, and a container 9. Examples of materials for the workpiece W include tungsten, molybdenum, silicon carbide, monocrystalline silicon, monocrystalline silicon carbide, gallium nitride, and polycrystalline silicon. Silicon carbide is also known as silicon carbide.

[0031] Multiple guide rollers 1 guide the movement of the wire electrode 2. Each guide roller 1 is cylindrical, extending along the Y-axis. The guide rollers 1 are rotated by a motor (not shown). In this embodiment, there are four guide rollers 1, but there can be more than four. Hereinafter, the four guide rollers 1 will be referred to as guide rollers 1a, 1b, 1c, and 1d. Each of the guide rollers 1a, 1b, 1c, and 1d is configured to rotate about the Y-axis. The rotation axes of each of the guide rollers 1a, 1b, 1c, and 1d are parallel to each other. The parallel rotation axes of the guide rollers 1a, 1b, 1c, and 1d enable the wire electrode 2 to move with high precision.

[0032] Guide rollers 1a, 1b, 1c, and 1d lie in a plane orthogonal to the rotation axis (in... Figure 1 Within the XZ plane, guide rollers 1a and 1b are arranged separately from each other in the X-axis and Z-axis directions. Specifically, guide rollers 1a and 1b are at the same height and are arranged separately from each other in the X-axis direction. Guide roller 1c and 1d are also at the same height and are arranged separately from each other in the X-axis direction. Guide roller 1c is positioned below guide roller 1b and separate from it, while guide roller 1d is positioned below guide roller 1a and separate from it. The rotation axis of each of guide rollers 1a, 1b, 1c, and 1d is positioned at a position corresponding to each vertex of the quadrilateral. Guide rollers 1a and 1b are positioned above the processing tank 6 and separate from it. Guide rollers 1c and 1d are disposed inside the processing tank 6. Part or all of guide rollers 1c and 1d are immersed in the processing fluid 10 of the processing tank 6.

[0033] The wire electrode 2 serves to cut the workpiece W. A single wire electrode 2, emitted from a feed tube (not shown), is repeatedly wound in the order of guide rollers 1a, 1b, 1c, and 1d. Specifically, the wire electrode 2 is wound multiple times at intervals on the outer circumferential surfaces of each of the guide rollers 1a, 1b, 1c, and 1d, along the rotation axes of each of the guide rollers 1a, 1b, 1c, and 1d.

[0034] The wire electrode 2 has multiple cutting wire portions 2a for cutting the workpiece W. These multiple cutting wire portions 2a are arranged separately from each other and face the workpiece W. The multiple cutting wire portions 2a are the portions of the wire electrode 2 that are mounted between guide rollers 1c and 1d. The multiple cutting wire portions 2a are arranged separately from each other in the direction along the respective rotation axes of guide rollers 1c and 1d. Preferably, the multiple cutting wire portions 2a are arranged parallel to each other. The wire electrode 2 travels as the guide rollers 1a, 1b, 1c, and 1d rotate, and finally winds from guide roller 1b onto a winding tube (not shown).

[0035] The power supply component 4 supplies power to the wire electrode 2, generating a discharge between the wire electrode 2 and the workpiece W. The power supply component 4 is cylindrical, extending along the Y-axis. In this embodiment, there are two power supply components 4, but this can be varied appropriately. Hereinafter, the two power supply components 4 will be referred to as power supply components 4a and 4b. Each power supply component 4a and 4b is in contact with the wire electrode 2. Specifically, each power supply component 4a and 4b is positioned below and in contact with the cutting wire portion 2a. The power supply components 4a and 4b are separated from each other in the X-axis direction, with the workpiece W between them.

[0036] One power supply unit 4a is disposed between the guide roller 1c and the machining fluid nozzle 8a (described later) in the X-axis direction. Another power supply unit 4b is disposed between the guide roller 1d and the machining fluid nozzle 8b (described later) in the X-axis direction. The wire EDM apparatus 100 has a machining power supply, such as a power supply panel (not shown). The power supply side terminals of the machining power supply are electrically connected to the power supply units 4a and 4b respectively. The ground side terminals of the machining power supply are electrically connected to the workpiece W. The voltage (voltage pulse) output from the machining power supply is applied between each cut wire portion 2a in the wire electrode 2 and the workpiece W. This allows a discharge to be generated between each cut wire portion 2a and the workpiece W.

[0037] The moving device 3 functions to move the wire electrode 2 and the workpiece W relative to each other. Specifically, the moving device 3 changes the relative position between each cutting wire portion 2a and the processing table 11 on which the workpiece W is placed. In this embodiment, the position of each cutting wire portion 2a in the Z-axis direction (vertical direction) is fixed, and the moving device 3 allows the processing table 11 and the workpiece W to move in the vertical direction. The moving device 3 is disposed below the processing table 11 and the workpiece W. The upper end of the moving device 3 is fixed to the processing table 11. The workpiece W is fixed in the moving device 3 via the processing table 11. Most of the moving device 3 is disposed at the bottom 6a of the processing tank 6. A portion of the moving device 3 is disposed inside the processing tank 6.

[0038] The wire electrical discharge machining (EDM) apparatus 100 performs EDM on the workpiece W by bringing the machining table 11, on which the workpiece W is placed, closer to or further away from the cutting line portion 2a. Furthermore, through EDM on the workpiece W, a machining groove W1, described later, is formed along the cutting line portion 2a on the workpiece W. Finally, the workpiece W is cut into multiple plate-shaped components. Additionally, the moving device 3 may be configured to move along the X-axis, Y-axis, and Z-axis directions.

[0039] The control unit 5 controls the moving device 3 and the processing power supply. The control unit 5 drives the moving device 3 and controls the relative position between each cutting wire section 2a and the processing table 11 on which the workpiece W is placed. The control unit 5 controls the operation by applying a command to the output voltage of the processing power supply to generate a discharge between each cutting wire section 2a and the workpiece W.

[0040] The machining tank 6 serves to contain the workpiece W and store the machining fluid 10. The machining tank 6 is box-shaped with an opening on its upper surface. The cut-off wire portions 2a that generate the discharge and the workpiece W are immersed in the machining fluid 10 in the machining tank 6. The machining fluid 10 helps to cool the wire electrodes 2 and the workpiece W, prevents fires, and removes machining chips generated by the electrical discharge machining.

[0041] A processing fluid tank 7 is located outside the processing tank 6 and serves to temporarily store the processing fluid 10. The processing fluid tank 7 is a hollow, box-shaped container. During processes such as setting up the workpiece W inside the processing tank 6, and when the operator prepares the processing tank 6, the processing fluid 10 is temporarily stored inside the processing fluid tank 7. A water supply and drainage mechanism (not shown) is used to discharge the processing fluid 10 from the processing tank 6 to the processing fluid tank 7 and to supply the processing fluid 10 from the processing fluid tank 7 to the processing tank 6. The water supply and drainage mechanism includes a pump, piping, etc. The liquid level 10a of the processing fluid 10 in the processing tank 6 is managed by the water supply and drainage mechanism to maintain an appropriate height. Specifically, when the liquid level 10a of the processing fluid 10 in the processing tank 6 is higher than a preset reference height, the processing fluid 10 is discharged from the processing tank 6 to the processing fluid tank 7. Conversely, when the liquid level 10a of the processing fluid 10 in the processing tank 6 is lower than the preset reference height, the processing fluid 10 is supplied from the processing fluid tank 7 to the processing tank 6.

[0042] The machining fluid nozzle 8 sprays machining fluid 10 between the wire electrode 2 and the workpiece W to remove machining chips generated by electrical discharge machining. One machining fluid nozzle 8 is arranged on each side of the workpiece W in the X-axis direction. In this embodiment, there are two machining fluid nozzles 8, but this can be varied appropriately. Hereinafter, the two machining fluid nozzles 8 will be referred to as machining fluid nozzles 8a and 8b. Each machining fluid nozzle 8a and 8b is arranged above and separate from each cutting line portion 2a. One machining fluid nozzle 8a is arranged between the workpiece W and the power supply component 4a in the X-axis direction. The other machining fluid nozzle 8b is arranged between the workpiece W and the power supply component 4b in the X-axis direction. Machining fluid is supplied from the machining fluid tank 7 via a machining fluid supply pipe (not shown).

[0043] Figure 2This is a front view showing the process of filling the container 9 with the processing fluid 10 according to Embodiment 1, and a diagram showing the state of the container 9's side 9c being contracted. Figure 3 This is a front view showing the process of filling the container 9 with the processing fluid 10 according to Embodiment 1, and a diagram showing the extended state of the side 9c of the container 9. Figure 2 and Figure 3 As shown, container 9 is positioned above the workpiece W and has a capacity capable of covering it. Container 9 is positioned near the surface 10a of the processing fluid 10 in the processing tank 6. Container 9 has an opening only on its bottom surface facing the workpiece W. An opening 9a extending through the bottom surface in the vertical direction is formed on the bottom surface of container 9. That is, the surfaces and edges of container 9, except for the bottom surface, are sealed.

[0044] The container 9 has an upper surface 9b disposed above and separate from the opening 9a on the bottom surface, and a side surface 9c extending from the upper surface 9b to the opening 9a and formed in a manner that allows free expansion and contraction in the vertical direction. The container 9 is fixed to surrounding components with the opening 9a located below the liquid surface 10a of the processing fluid 10 in the processing tank 6. In this embodiment, the container 9 is fixed to the upper surface of each of the processing fluid nozzles 8a and 8b, but it may also be fixed to other components. The side surface 9c is formed in a serpentine shape that allows expansion and contraction in the vertical direction. The side surface 9c is a cylindrical surface extending downward from the periphery of the upper surface 9b. A direct-acting actuator 12 is connected to the upper surface 9b. By moving the upper surface 9b in the vertical direction using the direct-acting actuator 12, the side surface 9c can be expanded and contracted in the vertical direction, thereby changing the capacity of the container 9.

[0045] Specifically, container 9 can change to state 1 and state 2, where state 1 is as follows: Figure 2 As shown, the side 9c is contracted, the opening 9a and the upper surface 9b are below the liquid surface 10a of the processing fluid 10 in the processing tank 6, and this second state is as follows. Figure 3 As shown, the side 9c is extended, the opening 9a is below the surface 10a of the processing fluid 10 in the processing tank 6, and the upper surface 9b is above the surface 10a of the processing fluid 10 in the processing tank 6. By changing the container 9 from the first state to the second state, processing fluid 10 is filled into the container 9 until the processing fluid 10 is above the surface 10a of the processing fluid 10 in the processing tank 6. That is, by extending the side 9c until the upper surface 9b of the container 9 is above the surface 10a of the processing fluid 10 in the processing tank 6, the surface 10b of the processing fluid 10 in the container 9 is above the surface 10a of the processing fluid 10 in the processing tank 6. The workpiece W can enter the interior of the container 9 in the second state as the electrical discharge machining progresses.

[0046] When the workpiece W is a semiconductor wafer material, in order to make the plate-shaped component (semiconductor wafer) cut from the workpiece W into a circular thin plate, the workpiece W is usually pre-shaped into a cylindrical shape. If a voltage of a certain value is applied to the gap between each cutting line 2a and the workpiece W, i.e., between the electrodes, and the electrode distance is within a certain range, a discharge occurs between the electrodes, the cutting line 2a heats up, and the workpiece W melts. As a result, multiple plate-shaped components are cut from the workpiece W at the same time. If the processing fluid 10 is supplied to the gap between each cutting line 2a and the workpiece W during the cutting process, the processing chips generated between each cutting line 2a and the workpiece W can be discharged out of the gap. Processing chips can cause short circuits between the cutting line 2a and the workpiece W; therefore, by supplying the processing fluid 10 to the gap between each cutting line 2a and the workpiece W, the frequency of short circuits can be reduced.

[0047] Next, refer to Figures 1 to 8 This describes a wire discharge machining method for performing electrical discharge machining on a workpiece W using the wire discharge machining apparatus 100 according to this embodiment. Figure 4 This is a flowchart illustrating the process of the wire electrical discharge machining method performed by the wire electrical discharge machining apparatus 100 according to Embodiment 1. Figure 5 This is a front view showing the container 9, the wire electrode 2, and the workpiece W surrounding the electrical discharge machining process in Embodiment 1. Figure 6 It is along Figure 5 The cross-sectional view along line VI-VI shown is a diagram of the wire electrode 2 and the workpiece W surrounding it during the electrical discharge machining process in Embodiment 1. Figure 7 This is a front view showing the container 9, the wire electrode 2, and the workpiece W surrounding the electrical discharge machining process in Embodiment 1. It is a diagram showing the state in which bubbles 14 are generated inside the container 9. Figure 8 This is a front view showing the container 9, the wire electrode 2, and the workpiece W after the electrical discharge machining in Embodiment 1 is completed. It is also a diagram showing the state in which a layer of gas 15 is generated inside the container 9.

[0048] The wire electrical discharge machining method includes a storage step, a filling step, and a machining step.

[0049] The storage step is in Figure 1 The step of storing the processing fluid 10 inside the processing tank 6 shown. In the storage step, the following steps are performed: Figure 4The processes described in steps S1 and S2 are as follows: In the storage step, processing fluid 10 is supplied from processing fluid tank 7 to the interior of processing tank 6 (step S1). This causes the level 10a of processing fluid 10 in processing tank 6 to rise. Next, in the storage step, it is confirmed whether the level 10a of processing fluid 10 in processing tank 6 has reached a preset height (step S2). If the level 10a of processing fluid 10 in processing tank 6 has not reached the preset height (in the case of No in step S2), the tank remains in standby mode while processing fluid 10 is continuously supplied to the interior of processing tank 6. A liquid level sensor (not shown) is used to determine whether the level 10a of processing fluid 10 in processing tank 6 has reached the preset height. The preset height must be higher than the opening 9a of container 9. If the level 10a of processing fluid 10 in processing tank 6 reaches the preset height (in the case of Yes in step S2), the supply of processing fluid 10 to the interior of processing tank 6 is stopped, and the process moves to the next filling step. Alternatively, the container 9 can be placed inside the processing tank 6 after the processing fluid 10 is supplied to the inside of the processing tank 6, causing the liquid level 10a of the processing fluid 10 in the processing tank 6 to rise. Or, the processing fluid 10 can be supplied to the inside of the processing tank 6 after the container 9 is placed inside the processing tank 6, causing the liquid level 10a of the processing fluid 10 in the processing tank 6 to rise.

[0050] like Figure 2 and Figure 3 As shown, the filling step involves lifting the upper surface 9b of container 9 before the start of electrical discharge machining (EDM) to fill the interior of container 9 with the processing fluid 10, creating a space 13 inside container 9 filled with the processing fluid 10 up to a position higher than the liquid level 10a of the processing fluid 10 in the processing tank 6. During the filling step, the following steps are performed: Figure 4 The processing in step S3 is shown. (As shown...) Figure 3 As shown, during the filling step, the upper surface 9b of the container 9 is lifted by the direct-acting actuator 12. Before the filling step, the container 9 is in a position... Figure 2 The first state is shown. That is, the side 9c of container 9 is contracted in the vertical direction, and the entire container 9 is below the liquid surface 10a of the processing fluid 10 in the processing tank 6. If the upper surface 9b of container 9 is pulled up from the first state by the direct-acting actuator 12, then container 9 becomes Figure 3 The second state is shown. That is, the side 9c of the container 9 extends in the vertical direction, the opening 9a and a part of the side 9c are below the liquid surface 10a of the processing liquid 10 in the processing tank 6, and the upper surface 9b and the remaining part of the side 9c are above the liquid surface 10a of the processing liquid 10 in the processing tank 6.

[0051] If container 9 is in the second state, the internal pressure of container 9 decreases, and the internal pressure of container 9 reaches equilibrium with the atmospheric pressure at the surface 10a of the processing fluid 10 applied to the processing tank 6. As a result, the processing fluid 10 of the processing tank 6 flows into the interior of container 9, forming a space 13 inside container 9 filled with processing fluid 10 up to a position above the surface 10a of the processing fluid 10 of the processing tank 6. That is, the surface 10b of the processing fluid 10 in container 9 is above the surface 10a of the processing fluid 10 in the processing tank 6. In the filling step, the upper surface 9b of container 9 is pulled up to a position where container 9 and the workpiece W do not contact each other during the processing steps described later. Furthermore, in the filling step, the amount of pulling up the upper surface 9b of container 9 (the amount of movement of the direct-acting actuator 12) can be appropriately adjusted according to the size of the workpiece W.

[0052] like Figure 5 As shown, the processing step involves moving the workpiece W while performing electrical discharge machining (EDM), causing the workpiece W to enter the interior of the container 9 as the EDM progresses. During this processing step, the following steps are performed: Figure 4 The processing steps S4 to S6 are shown. In the processing step, electrical discharge machining begins (step S4). Specifically, by applying a voltage output from the processing power supply between each cut wire 2a and the workpiece W, a discharge is generated between each cut wire 2a and the workpiece W. Furthermore, in the processing step, the moving device 3 begins to move upward toward a pre-set position where the electrical discharge machining is completed, and the workpiece W begins to move upward at an appropriate speed. If the workpiece W is moved upward relative to the wire electrode 2, the workpiece W melts due to the discharge generated between each cut wire 2a and the workpiece W.

[0053] like Figure 6 As shown, if the moving device 3 is further moved upwards, and the workpiece W is further moved upwards relative to the wire electrode 2, the electrical discharge machining on the workpiece W is advanced, forming multiple machining grooves W1 on the workpiece W. Figure 7 and Figure 8 As shown, the workpiece W moves upwards as the electrical discharge machining (EDM) progresses, entering the container 9 in its second state. Next, in the machining process, it is confirmed whether the moving device 3 has reached the position where the EDM is complete (step S5). If the moving device 3 has not reached the position where the EDM is complete (if No in step S5), it remains in standby mode while continuing to move upwards. If the moving device 3 has reached the position where the EDM is complete (if Yes in step S5), the moving device 3 is stopped, and the EDM is completed (step S6).

[0054] In addition, such as Figure 7As shown, during the electrical discharge machining (EDM) process, the machining fluid 10 vaporizes due to the heat generated, thereby producing bubbles 14, or the bubbles 14 mix into the machining fluid 10 ejected from the machining fluid nozzle 8. Figure 8 As shown, due to these bubbles 14, air, gases, and other gases 15 accumulate inside the container 9, creating a layer of gas 15. Therefore, Figure 8 The liquid level 10c of the processing fluid 10 in container 9 after the discharge machining is shown is higher than that of the liquid level 10c of the processing fluid 10. Figure 3 The liquid level 10b of the processing fluid 10 in the container 9 shown at the start of the electrical discharge machining is located at the bottom. Therefore, it is assumed that gas 15 will accumulate inside the container 9. In order to prevent the workpiece W from being exposed to the layer of gas 15 during the electrical discharge machining process, it is only necessary to design the volume of the container 9 to be sufficiently large.

[0055] Next, the effects of the wire electrical discharge machining apparatus 100 according to this embodiment will be explained.

[0056] In this embodiment, such as Figure 2 and Figure 3 As shown, the wire electrical discharge machining apparatus 100 includes a container 9, which is disposed above the workpiece W and has a capacity capable of covering the workpiece W, with an opening only facing the bottom surface of the workpiece W. Furthermore, in this embodiment, the container 9 has an upper surface 9b disposed above and separate from the opening 9a on the bottom surface, and a side surface 9c extending from the upper surface 9b to the opening 9a and formed in a manner that allows free expansion and contraction in the vertical direction. In this embodiment, the container 9 can be changed to a first state and a second state. The first state is that the side surface 9c is contracted, and the opening 9a and the upper surface 9b are below the liquid surface 10a of the machining fluid 10 in the machining tank 6. The second state is that the side surface 9c is extended, and the opening 9a is below the liquid surface 10a of the machining fluid 10 in the machining tank 6, while the upper surface 9b is above the liquid surface 10a of the machining fluid 10 in the machining tank 6. Furthermore, in this embodiment, by changing the container 9 from the first state to the second state, the container 9 is filled with processing fluid 10 up to a position higher than the liquid level 10a of the processing fluid 10 in the processing tank 6. Additionally, in this embodiment, the workpiece W can enter the container 9 in the second state as the electrical discharge machining progresses. In summary, this embodiment employs a structure in which the liquid level 10b of the processing fluid 10 in the container 9 is partially formed by filling the container 9 with processing fluid 10, thus creating a space 13 where the liquid level 10b of the processing fluid 10 in the container 9 is higher than the liquid level 10a of the processing fluid 10 in the processing tank 6. The workpiece W is then subjected to electrical discharge machining while being completely immersed in the processing fluid 10 within this space 13. With this structure, even when the workpiece W is moved upwards relative to the wire electrode 2 during electrical discharge machining, it is possible to avoid… Figure 6 The machining groove W1 shown is compared to Figure 5In the container 9 shown, the liquid level 10b of the processing fluid 10 is at the top (the processing tank W1 is exposed to gas), which suppresses the narrowing of the processing tank W1 due to the surface tension of the processing fluid 10 remaining in the processing tank W1. Therefore, the flow of the processing fluid 10 facilitates the discharge of machining chips generated by electrical discharge machining out of the processing tank W1, suppressing abnormal discharge and wire breakage of the wire electrode 2, thereby improving the processing quality and productivity of the workpiece W.

[0057] like Figure 6 As shown, when multiple cutting lines 2a are arranged side-by-side to cut multiple plate-shaped parts from the workpiece W, the surface tension of the machining fluid 10 remaining in the machining tank W1 can result in machining tanks W1 that are either narrow or wide, leading to differences in the discharge of machining chips in each machining tank W1 and causing fluctuations in the processing quality of each plate-shaped part. In this embodiment, by avoiding placing the machining tank W1 above the liquid surface 10b of the machining fluid 10 in the container 9, it is possible to suppress the narrowing or widening of the machining tank W1 due to the surface tension of the machining fluid 10 remaining in the machining tank W1. Therefore, differences in the discharge of machining chips in each machining tank W1 are less likely to occur, and fluctuations in the processing quality of each plate-shaped part are less likely to occur.

[0058] Furthermore, in the final stage of electrical discharge machining, since the cross-sectional area of ​​the connecting portion (i.e., the uncut portion) of the workpiece W is very small relative to the area of ​​the machining tank W1, the workpiece W may break due to the surface tension of the machining fluid 10 remaining in the machining tank W1. In this embodiment, by avoiding placing the machining tank W1 above the liquid surface 10b of the machining fluid 10 in the container 9, the breakage of the workpiece W due to the surface tension of the machining fluid 10 remaining in the machining tank W1 can be suppressed.

[0059] In this embodiment, by adopting the structure described in paragraph 0040 (the third paragraph from this point), compared to the case where the depth of the machining tank 6 is set to be greater than or equal to twice the height of the workpiece W in order to perform electrical discharge machining while the workpiece W is entirely immersed in the machining fluid 10, it is possible to achieve a lighter and smaller machining tank 6. This prevents the overall enlargement of the wire electrical discharge machining apparatus 100. Furthermore, it also allows for a reduction in the amount of machining fluid 10 used.

[0060] In this embodiment, such as Figures 6 to 8 As shown, the workpiece W is moved from below to above relative to the wire electrode 2 to perform electrical discharge machining. Since the bubbles 14 generated by the vaporization of the processing fluid 10 are not easily accumulated in the processing tank W1 where the discharge phenomenon occurs, the electrical discharge machining is stable.

[0061] As described above, in this embodiment, even when the workpiece W is moved from below to above relative to the wire electrode 2 to perform electrical discharge machining, it is possible to suppress the overall enlargement of the wire electrical discharge machining apparatus 100 and to perform electrical discharge machining on the workpiece W while it is completely immersed in the processing fluid 10.

[0062] The following describes a variation of Implementation 1.

[0063] In this embodiment, such as Figure 7 and Figure 8 As shown, an example illustrates a case where the shape of side 9c is formed by alternating and repeating protrusions protruding into the container 9 and protruding outwards from the container 9, and is generally parallel in the vertical direction from the opening 9a toward the upper surface 9b, but is not limited to this. For example, as... Figure 9 and Figure 10 As shown, the shape of the side 9c can also be a shape that gradually widens from the opening 9a toward the upper surface 9b. Figure 9 This is a front view showing the container 9, the wire electrode 2, and the workpiece W surrounding the electrical discharge machining process in a modified example of embodiment 1. It is a diagram showing the state in which bubbles 14 are generated inside the container 9. Figure 10 This is a front view showing the container 9, the wire electrode 2, and the workpiece W after the discharge machining is completed in a modified example of embodiment 1. It is also a diagram showing the state in which a layer of gas 15 is generated inside the container 9.

[0064] The shape of side 9c is such that the cross-sectional area of ​​container 9 widens from bottom to top. In this modified example, the volume of container 9 can be increased. Therefore, even if a layer of gas 15 is formed inside container 9 due to bubbles 14 generated during the electrical discharge machining process, the workpiece W will not be exposed to the layer of gas 15 during the electrical discharge machining process, and the workpiece W can be electrically processed while being completely immersed in the processing fluid 10. As a result, the narrowing of the processing tank W1 due to the surface tension of the processing fluid 10 remaining in the processing tank W1 can be suppressed. Therefore, the flow of the processing fluid 10 makes it easy to discharge the machining chips generated by the electrical discharge machining to the outside of the processing tank W1, suppressing the occurrence of abnormal discharge and wire breakage of the wire electrode 2, thereby improving the processing quality of the workpiece W and the productivity of the workpiece W.

[0065] In this embodiment, the filling step and the processing step are performed at different times (the filling step is performed before the start of the electrical discharge machining), but the filling step and the processing step can also be performed simultaneously. That is, the wire electrical discharge machining method can also include a processing step that combines the above-mentioned filling step and processing step. This processing step is the following step, namely, while... Figure 5The upper surface 9b of the container 9 shown is raised, and processing fluid 10 is filled into the container 9. A space 13 filled with processing fluid 10 is formed inside the container 9 up to a position higher than the liquid surface 10a of the processing fluid 10 in the processing tank 6. While the workpiece W is moved, electrical discharge machining is performed, and the workpiece W is brought into the interior of the container 9 as the electrical discharge machining progresses. That is, the upper surface 9b of the container 9 can also be gradually raised in accordance with the progress of the electrical discharge machining while the workpiece W is brought into the interior of the container 9.

[0066] Implementation Method 2

[0067] Next, refer to Figure 11 and Figure 12 The wire electrical discharge machining apparatus 100A according to Embodiment 2 will be described. Figure 11 This is a front view showing the container 9, the wire electrode 2, and the workpiece W around the wire electrical discharge machining apparatus 100A according to Embodiment 2 during the electrical discharge machining process. It is also a diagram showing the state in which a layer of bubbles 14 and gas 15 is generated inside the container 9. Figure 12 This is a front view showing the container 9, the wire electrode 2, and the workpiece W surrounding the wire electrical discharge machining apparatus 100A according to Embodiment 2. It also shows the state in which the gas 15 accumulated inside the container 9 is discharged. In this embodiment, the difference from Embodiment 1 is that the gas 15 accumulated inside the container 9 during the electrical discharge machining process is discharged to the outside of the container 9. Furthermore, in Embodiment 2, parts that are repeated with those in Embodiment 1 are labeled with the same reference numerals and their descriptions are omitted.

[0068] The position of the workpiece W can be changed to enter. Figure 11 The processing position inside container 9 in state 2 and the retreat to Figure 12 The first state shown is the external retracted position of container 9. By changing container 9 from the second state to the first state, the gas 15 accumulated inside container 9 is discharged to the outside of container 9.

[0069] Next, refer to Figures 11 to 13 This describes a wire discharge machining method for performing electrical discharge machining on a workpiece W using the wire discharge machining apparatus 100A according to this embodiment. Figure 13 This is a flowchart illustrating the process of the wire electrical discharge machining method performed by the wire electrical discharge machining apparatus 100A according to Embodiment 2.

[0070] The wire discharge machining method includes a storage step, a filling step, a machining step, an adjustment step, a retraction step, a discharge step, and a reopening step. Since the storage step (steps S11, S12) and the filling step (step S13) are the same as the storage step (steps S1, S2) and the filling step (step S3) of the wire discharge machining method according to Embodiment 1 above, their description is omitted here.

[0071] The processing steps (steps S14, S16, S17) of this embodiment are the same as the processing steps (steps S4, S5, S6) of the line discharge processing method described in Embodiment 1 above. However, the difference between the processing steps of this embodiment and the processing steps of the line discharge processing method described in Embodiment 1 is that a determination is made as to whether a certain amount of gas 15 has accumulated inside the container 9 during the discharge processing (step S15). In the processing steps of this embodiment, if a certain amount of gas 15 has not accumulated inside the container 9 (if No in step S15), it is confirmed whether the moving device 3 has moved to the position where the discharge processing is completed (step S16). Next, in the processing step, if the moving device 3 has not moved to the position where the discharge processing is completed (if No in step S16), the processing of step S15 is repeated. In the processing step, if the moving device 3 has moved to the position where the discharge processing is completed (if Yes in step S16), the moving device 3 is stopped, and the discharge processing is completed (step S17). On the other hand, if a certain amount of gas 15 accumulates inside the container 9 during the processing step (if Yes is in step S15), the process moves to the adjustment step (step S18).

[0072] The adjustment step is a step in which the voltage applied between the wire electrode 2 and the workpiece W is adjusted when a certain amount of gas 15 accumulates inside the container 9 during the electrical discharge machining process. In this adjustment step, the following steps are performed: Figure 13 The process shown in step S18. In the adjustment step, the voltage applied between each cutting wire portion 2a and the workpiece W is adjusted so that the portion of the workpiece W that has undergone electrical discharge machining (machining groove W1) is not damaged due to accidental discharge. In the adjustment step, the voltage is reduced or the application of voltage is stopped. However, depending on the diameter of the wire electrode 2, the width of the machining groove W1, etc., sometimes the adjustment step is not necessary. In such cases, the adjustment step can be omitted.

[0073] like Figure 12 As shown, the retraction step is the step of retracting the workpiece W to the outside of the container 9. In the retraction step, the following steps are performed: Figure 13The process shown in step S19. In the retraction step, the workpiece W is retracted to the outside of the container 9 so that the workpiece W and the container 9 do not contact each other. In the retraction step, the moving device 3 begins to move downward, starting to move downward towards the workpiece W at an appropriate speed. If the workpiece W is moved downward relative to the container 9, the position of the workpiece W is changed to a retracted position outside the container 9 in the first state.

[0074] like Figure 12 As shown, the discharge step involves pressing the upper surface 9b of container 9 towards the opening 9a, causing the side 9c to contract, thereby discharging the gas 15 accumulated inside container 9 to the outside of container 9. In this discharge step, the following steps are performed: Figure 13 The process shown in step S20. In the discharge step, the upper surface 9b of container 9 is pressed down by the direct-acting actuator 12. As a result, the side 9c of container 9 contracts in the vertical direction, and the entire container 9 is positioned below the liquid surface 10a of the processing liquid 10 in the processing tank 6, discharging the gas 15 accumulated inside container 9 to the outside of container 9. That is, by changing container 9 from the second state to the first state, the gas 15 accumulated inside container 9 is discharged to the outside of container 9.

[0075] like Figure 11 As shown, the reopening step involves pulling the upper surface 9b of container 9 in a direction away from opening 9a, causing the side 9c to extend, and then allowing the workpiece W to enter the interior of container 9 to restart the electrical discharge machining process. In the reopening step, the following steps are performed: Figure 13 The processing steps S21 to S23 are shown below. First, in the reopening step, the upper surface 9b of the container 9 is pulled up by the direct-acting actuator 12 (step S21). As a result, the side 9c of the container 9 extends in the vertical direction, with the opening 9a and a portion of the side 9c below the surface 10a of the processing liquid 10 in the processing tank 6, and the remaining portion of the upper surface 9b and the side 9c above the surface 10a of the processing liquid 10 in the processing tank 6. Next, in the reopening step, the moving device 3 begins to move upward, moving the workpiece W upward at an appropriate speed, returning the moving device 3 and the workpiece W to their previous positions (step S22). As a result, the position of the workpiece W is changed to the processing position inside the container 9 in the second state. Next, in the reopening step, by applying a voltage output from the processing power supply between each cutting wire 2a and the workpiece W, a discharge is generated between each cutting wire 2a and the workpiece W, and the discharge processing is restarted (step S23).

[0076] In the wire discharge machining method according to this embodiment, discharge machining is performed while repeatedly performing the above-described machining steps, adjustment steps, retraction steps, discharge steps, and reopening steps. Furthermore, the timing of the discharge step (the timing for discharging the gas 15 accumulated inside the container 9 to the outside of the container 9) can be arbitrarily set. For example, the relationship between the discharge machining time and the volume of the gas 15 accumulated inside the container 9 can be determined in advance through experiments, and the discharge step is performed at a time when an arbitrarily set discharge machining time is reached. Alternatively, for example, it is also possible to pre-determine the relationship between the discharge machining time and the volume of the gas 15 accumulated inside the container 9. Figure 11 A liquid level sensor 16 is installed on the upper surface 9b of the container 9 shown. The discharge step is performed at a time when the liquid level 10c of the processing fluid 10 drops to an arbitrary set position.

[0077] Next, the effects of the wire electrical discharge machining apparatus 100A according to this embodiment will be explained.

[0078] In this embodiment, such as Figure 11 and Figure 12 As shown, the position of the workpiece W can be changed to a processing position inside the container 9 in the second state and a retreat position outside the container 9 in the first state. Furthermore, in this embodiment, by changing the container 9 from the second state to the first state, the gas 15 accumulated inside the container 9 is discharged to the outside of the container 9. With these structures, even if the container 9 cannot be designed to be large enough due to size limitations of the wire EDM apparatus 100A, the workpiece W will not be exposed to the layer of gas 15 during EDM, and EDM can be performed on the workpiece W while it is completely immersed in the processing fluid 10. This suppresses the narrowing of the processing tank W1 due to the surface tension of the processing fluid 10 remaining in the processing tank W1. Therefore, the flow of the processing fluid 10 facilitates the discharge of machining debris generated by EDM to the outside of the processing tank W1, suppressing abnormal discharge and wire breakage of the wire electrode 2, thereby improving the processing quality and productivity of the workpiece W.

[0079] Implementation Method 3

[0080] Next, refer to Figure 14 and Figure 15 The wire electrical discharge machining apparatus 100B according to Embodiment 3 will be described. Figure 14 This is a front view of the wire electrical discharge machining apparatus 100B according to Embodiment 3. Figure 15This is a front view of the wire electrical discharge machining apparatus 100B according to Embodiment 3, showing the state in which the bubbles 14 generated inside the container 9 are discharged. In this embodiment, the difference from Embodiments 1 and 2 is that the container 9 does not freely expand or contract, and the wire electrical discharge machining apparatus 100B has a suction device 17. Furthermore, in Embodiment 3, parts that are repeated with those in Embodiments 1 and 2 are labeled with the same reference numerals and their descriptions are omitted.

[0081] The side 9c of container 9 is not formed by freely expanding and contracting in the vertical direction. Container 9 can be changed to state 1 and state 2, state 1 as follows: Figure 14 As shown, container 9 is entirely disposed in processing fluid 10 in processing tank 6, in the second state as follows. Figure 15 As shown, the opening 9a is below the surface 10a of the processing fluid 10 in the processing tank 6, and the upper surface 9b is above the surface 10a of the processing fluid 10 in the processing tank 6. By changing the container 9 from the first state to the second state, the processing fluid 10 is filled into the container 9 up to a position above the surface 10a of the processing fluid 10 in the processing tank 6. The workpiece W can enter the interior of the container 9 in the second state as the electrical discharge machining progresses.

[0082] The suction device 17 is connected to the upper surface 9b of the container 9 and is used to attract bubbles 14 and gas 15 generated inside the container 9. The suction device 17 has a suction tube 17a and a suction device 17b. One end of the suction tube 17a is connected to the upper surface 9b of the container 9 and communicates with the interior of the container 9. The other end of the suction tube 17a is disposed in the processing fluid 10 stored inside the processing fluid tank 7. The processing fluid tank 7 is located below the processing tank 6 and the container 9. The suction device 17b is disposed in the middle section of the suction tube 17a.

[0083] Next, refer to Figure 14 and Figure 15 This describes a wire discharge machining method for performing electrical discharge machining on a workpiece W using the wire discharge machining apparatus 100B according to this embodiment.

[0084] The wire discharge machining method includes a storage step, a filling step, and a machining step. Since the filling step is the same as the filling step in the wire discharge machining method described in Embodiment 1 above, its description is omitted here.

[0085] The storage and processing steps in this embodiment are largely the same as those in the wire discharge machining method described in Embodiment 1 above. However, the difference lies in the use of a suction device 17 to attract the bubbles 14 and gas 15 generated inside the container 9. That is, as... Figure 14As shown, in the storage step of this embodiment, if gas 15 is generated inside the container 9 during the process of placing the container 9 in the processing liquid 10 of the processing tank 6, or during the process of supplying the processing liquid 10 into the processing tank 6 after placing the container 9 inside the processing tank 6 and causing the liquid level 10a of the processing liquid 10 to rise, the gas 15 is drawn in by the suction device 17. This allows the gas 15 to be discharged to the outside of the container 9, and allows the inside of the container 9, the inside of the suction tube 17a, and the inside of the suction device 17b to be pre-filled with the processing liquid 10. In this state, as... Figure 15 As shown, if the upper surface 9b of the container 9 is pulled up by the direct-acting actuator 12, the container 9 will be filled with processing fluid 10 until it is above the liquid level 10a of the processing fluid 10 in the processing tank 6. That is, the liquid level 10b of the processing fluid 10 in the container 9 is above the liquid level 10a of the processing fluid 10 in the processing tank 6.

[0086] During the processing steps, i.e., during electrical discharge machining, bubbles 14 are generated due to the vaporization of the processing fluid 10, or bubbles 14 are mixed into the processing fluid 10 sprayed from the processing fluid nozzle 8. Regarding this, as shown in this embodiment, if the interior of the container 9, the interior of the suction pipe 17a, and the interior of the suction device 17b are filled with the processing fluid 10, bubbles 14 will be continuously discharged from the upper surface 9b of the container 9 through the suction pipe 17a to the interior of the processing fluid tank 7 via the siphon principle, even if the suction device 17b is not activated. Therefore, in this embodiment, even if bubbles 14 are generated inside the container 9 during electrical discharge machining, the bubbles 14 can be quickly discharged to the outside of the container 9.

[0087] Next, the effects of the wire electrical discharge machining apparatus 100B according to this embodiment will be explained.

[0088] In this embodiment, such as Figure 14 and Figure 15 As shown, the wire electrical discharge machining apparatus 100B has a suction device 17 connected to the upper surface 9b of the container 9, for attracting bubbles 14 and gas 15 generated inside the container 9. This structure allows the bubbles 14 and gas 15 generated inside the container 9 to be discharged to the outside of the container 9.

[0089] The structure shown in the above embodiments is an example and can be combined with other known technologies. The embodiments can also be combined with each other, and without departing from the main idea, a part of the structure can be omitted or changed.

[0090] Explanation of the label

[0091] 1, 1a, 1b, 1c, 1d Guide rollers; 2 Wire electrode; 2a Wire cutting section; 3 Moving device; 4, 4a, 4b Power supply unit; 5 Control unit; 6 Machining tank; 6a Bottom; 7 Machining fluid tank; 8, 8a, 8b Machining fluid nozzle; 9 Container; 9a Opening; 9b Upper surface; 9c Side; 10 Machining fluid; 10a, 10b, 10c Liquid surface; 11 Machining table; 12 Direct actuator; 13 Space; 14 Bubble; 15 Gas; 16 Liquid level sensor; 17 Suction device; 17a Suction tube; 17b Suctioner; 100, 100A, 100B Wire EDM device; 101 Arrow; W Workpiece; W1 Machining tank.

Claims

1. A wire electrical discharge machining (EDM) apparatus, which generates a discharge between a wire electrode and a workpiece to perform EDM on the workpiece. The wire electrical discharge machining apparatus is characterized by having: A moving device that moves the wire electrode and the workpiece relative to each other; A control unit that controls the mobile device; A processing tank that contains the workpiece and stores processing fluid; as well as A container, positioned above the workpiece, has a capacity to cover the workpiece and has an opening only facing the bottom surface of the workpiece. The container has an upper surface disposed above and separate from the opening on the bottom surface, and a side surface extending from the upper surface to the opening and formed in a manner that allows it to freely expand and contract in the vertical direction. The container can be changed to a first state and a second state. In the first state, the sides are contracted, and the opening and the upper surface are below the surface of the processing fluid in the processing tank. In the second state, the sides are extended, the opening is below the surface of the processing fluid in the processing tank, and the upper surface is above the surface of the processing fluid in the processing tank. By changing the container from the first state to the second state, the container is filled with processing fluid up to a position above the level of the processing fluid in the processing tank. As the electrical discharge machining progresses, the workpiece is able to enter the interior of the container in the second state.

2. A wire electrical discharge machining (EDM) apparatus, which generates a discharge between a wire electrode and a workpiece to perform EDM on the workpiece. The wire electrical discharge machining apparatus is characterized by having: A moving device that moves the wire electrode and the workpiece relative to each other; A control unit that controls the mobile device; A processing tank that contains the workpiece and stores processing fluid; as well as A container, positioned above the workpiece, has a capacity to cover the workpiece and has an opening only facing the bottom surface of the workpiece. The container has an upper surface disposed above and separate from the opening on the bottom surface, and a side surface extending from the upper surface to the opening. The container can be changed to a first state and a second state. In the first state, the container is entirely disposed in the processing fluid in the processing tank. In the second state, the opening is located below the surface of the processing fluid in the processing tank, and the upper surface is located above the surface of the processing fluid in the processing tank. By changing the container from the first state to the second state, the container is filled with processing fluid up to a position above the level of the processing fluid in the processing tank. As the electrical discharge machining progresses, the workpiece is able to enter the interior of the container in the second state.

3. The wire electrical discharge machining apparatus according to claim 1 or 2, characterized in that, The side surface has a shape that gradually widens from the opening toward the upper surface.

4. The wire electrical discharge machining apparatus according to claim 1 or 2, characterized in that, It has an attraction device connected to the upper surface of the container for attracting bubbles and gas generated inside the container.

5. The wire electrical discharge machining apparatus according to claim 1, characterized in that, The position of the workpiece can be changed to a processing position inside the container in the second state and a retreating position outside the container in the first state. By changing the container from the second state to the first state, the gas accumulated inside the container is discharged to the outside of the container.

6. A wire electrical discharge machining method, wherein the workpiece is subjected to electrical discharge machining using the wire electrical discharge machining apparatus according to any one of claims 1 to 5. The wire electrical discharge machining method is characterized by including: The filling step involves filling the container with the processing fluid before the start of the electrical discharge machining (EDM), creating a space inside the container filled with the processing fluid up to a level higher than the surface of the processing fluid in the machining tank; and The processing steps involve moving the workpiece while performing electrical discharge machining (EDM), and as the EDM progresses, the workpiece enters the interior of the container.

7. A wire electrical discharge machining method, wherein the workpiece is subjected to electrical discharge machining using the wire electrical discharge machining apparatus according to any one of claims 1 to 5. The wire electrical discharge machining method is characterized by including: The processing steps involve lifting the upper surface of the container, filling the container with the processing fluid to form a space inside the container filled with the processing fluid up to a position higher than the liquid level of the processing tank, while moving the workpiece to perform electrical discharge processing, and as the electrical discharge processing progresses, the workpiece enters the interior of the container.

8. A wire electrical discharge machining method, wherein the workpiece is subjected to electrical discharge machining using the wire electrical discharge machining apparatus as described in claim 1 or 5. The wire electrical discharge machining method is characterized by including: In the filling step, before the start of the electrical discharge machining, the upper surface of the container is lifted and the machining fluid is filled into the container, forming a space inside the container filled with the machining fluid up to a position higher than the liquid level of the machining tank. The processing steps involve moving the workpiece while performing electrical discharge machining, and as the electrical discharge machining progresses, the workpiece enters the interior of the container. The retraction step involves retracting the workpiece to the outside of the container when a certain amount of gas accumulates inside the container during the electrical discharge machining process. The discharge step involves pressing the upper surface of the container toward the opening to contract the sides, thereby discharging the gas accumulated inside the container to the outside of the container. as well as The restart step involves stretching the side of the container by pulling its upper surface away from the opening, then allowing the workpiece to enter the container and restarting the electrical discharge machining process. While repeating the processing steps, the retraction steps, the discharge steps, and the reopening steps, electrical discharge machining is performed.

9. The wire electrical discharge machining method according to claim 8, characterized in that, The process includes an adjustment step, which, between the processing step and the retraction step, adjusts the voltage applied between the wire electrode and the workpiece when a certain amount of gas accumulates inside the container during the electrical discharge machining process. While repeating the processing steps, adjustment steps, retraction steps, discharge steps, and reopening steps, electrical discharge machining is performed.

10. A wire electrical discharge machining method, wherein the workpiece is subjected to electrical discharge machining using the wire electrical discharge machining apparatus according to claim 1 or 5. The wire electrical discharge machining method is characterized by including: The processing steps involve lifting the upper surface of the container, filling the container with the processing fluid to form a space inside the container filled with the processing fluid up to a level higher than the liquid level of the processing fluid stored in the processing tank, while moving the workpiece to perform electrical discharge machining, and as the electrical discharge machining progresses, the workpiece enters the interior of the container. The retraction step involves retracting the workpiece to the outside of the container when a certain amount of gas accumulates inside the container during the electrical discharge machining process. The discharge step involves pressing the upper surface of the container toward the opening to contract the sides, thereby discharging the gas accumulated inside the container to the outside of the container. as well as The restart step involves stretching the side of the container by pulling its upper surface away from the opening, then allowing the workpiece to enter the container and restarting the electrical discharge machining process. While repeating the processing steps, the retraction steps, the discharge steps, and the reopening steps, electrical discharge machining is performed.

11. The wire electrical discharge machining method according to claim 10, characterized in that, The process includes an adjustment step, which, between the processing step and the retraction step, adjusts the voltage applied between the wire electrode and the workpiece when a certain amount of gas accumulates inside the container during the electrical discharge machining process. While repeating the processing steps, adjustment steps, retraction steps, discharge steps, and reopening steps, electrical discharge machining is performed.

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