Wire electric discharge machining apparatus and method for adjusting flow rate and flow rate ratio of jet in wire electric discharge machining apparatus

Abstract

To provide a device and a method capable of relatively easily automating the adjustment of the flow rate and the flow rate ratio of upper and lower jet nozzles in a wire electric discharge machining device and being easily introduced.SOLUTION: An upper flow passage group including a plurality of parallel bypass flow passages for supplying the machining liquid to the upper jet nozzle, the plurality of bypass flow passages having different flow rates, and a lower flow passage group including a plurality of parallel bypass flow passages for supplying the machining liquid to the lower jet nozzle; The wire electric discharge machine includes an upper valve that opens and closes a flow path, a lower valve provided in a lower flow path group, a jet pump that supplies a dielectric working fluid to the upper flow path group and the lower flow path group, a flow rate control unit that controls a flow rate of the jet pump, and a flow rate ratio control unit that individually controls opening and closing of the upper valve and the lower valve.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a wire electric discharge machining apparatus that uses a wire electrode as a tool electrode to perform electric discharge machining on a workpiece to form a desired shape, and to a method that can simultaneously adjust the flow rate and the flow rate ratio of upper and lower jets that supply machining fluid to a machining gap in the wire electric discharge machining apparatus. [Background technology]

[0002] A wire electric discharge machining apparatus accommodates a workpiece in a machining tank, applies a machining voltage to a machining gap formed between a wire electrode and a workpiece positioned opposite the wire electrode, and moves the wire electrode and the workpiece relative to each other along a predetermined path while generating intermittent discharges. This type of wire electric discharge machining apparatus uses discharge energy to machine the workpiece into a desired shape. In this type of wire electric discharge machining apparatus, if there is nothing in the machining gap, a so-called aerial discharge state, it is difficult to generate continuous spark discharges suitable for machining, and machining does not progress. Therefore, an insulating and dielectric machining fluid is supplied to the machining gap as a machining medium, and secondary discharges are induced through fine metal powder dispersed in the machining fluid.

[0003] The machining fluid supplied to the machining gap as a machining medium also serves as a cleaning fluid, removing contaminated machining fluid containing unwanted metal chips from the machining gap, which has ionized due to repeated dielectric breakdown caused by successive discharges in a short period of time, thereby restoring the insulation of the machining gap. The machining fluid also serves as a coolant, cooling the machining gap, whose temperature has risen due to heat generated by discharges. A general-purpose wire electric discharge machining device is configured to spray machining fluid coaxially with the wire electrode toward the machining gap from a pair of jet nozzles located above and below the workpiece during machining. As a result, the insulation of the machining gap can be efficiently and effectively restored in a short period of time, the machining gap can be cooled to prevent wire electrode breakage, and the machining gap can always be maintained in a state suitable for machining.

[0004] The flow rate of the machining fluid supplied to the machining gap is particularly important in finish machining after rough machining. For example, if the supply of clean machining fluid is insufficient, the concentration of machining debris increases, causing concentrated discharges and deteriorating machining accuracy. Conversely, if the supply of machining fluid is excessive, the flow of the machining fluid can cause the wire electrode to vibrate, or even the necessary amount of tiny metal powder can be removed from the machining gap, preventing stable EDM through appropriate secondary discharges, again resulting in a deterioration in machining accuracy.

[0005] As an invention for changing the flow rate of machining fluid into the machining gap, Patent Document 1 discloses an electric discharge machine in which the flow rate of machining fluid is changed by opening and closing flow-variable valves connected in parallel. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Special Publication No. 6-22763 Summary of the Invention [Problem to be solved by the invention]

[0007] The appropriate flow rate of machining fluid in the machining gap during finish machining is related to many conditions, including the thickness and material of the workpiece, as well as close contact machining, in which the jet nozzle and workpiece are in close contact, and floating machining, in which the jet nozzle and workpiece are separated. Depending on the conditions, the appropriate flow rate of machining fluid supplied from the upper and lower jet nozzles may differ from each other. In other words, to determine the appropriate machining fluid to be supplied to the machining gap by the upper and lower jet nozzles, it is necessary to adjust not only the flow rate but also the flow rate ratio of the upper and lower jet nozzles.

[0008] However, there is no requirement to adjust the flow rate ratio of the upper and lower jet nozzles so precisely. Furthermore, in most machining processes, the flow rate ratio of the upper and lower jet nozzles can be the same, and it is sufficient to adjust the output of the pump shared by the upper and lower jet nozzles according to the machining conditions. Therefore, currently, the flow rates and flow rate ratios of the upper and lower jet nozzles are manually adjusted by an operator using needle valves installed in the upper and lower jet flow paths while visually checking the analog flow meters. This creates problems such as individual differences between operators and the tendency for setting errors to occur, placing a burden on the operator.

[0009] For this reason, if it were possible to automate the adjustment of the flow rate and flow rate ratio of the upper and lower jet nozzles relatively easily, it would be possible to reduce the burden on the operator during necessary processing. For example, one possible method would be to replace the needle valves with proportional control valves and install flow sensors in each flow path for the upper and lower jets. In this case, feedback control could be performed using the flow sensor values. However, such a structure and method would significantly increase the introduction cost, making it difficult to implement.

[0010] The present invention has been made in view of the above circumstances, and aims to provide a wire electric discharge machining apparatus that can be easily automated and introduced, and a method for adjusting the flow rates and flow rate ratios of the upper and lower jet nozzles in the wire electric discharge machining apparatus. [Means for solving the problem]

[0011] According to the present invention, there is provided a wire electric discharge machining apparatus comprising: an upper jet nozzle that supplies machining fluid from above to a machining gap formed between an electrode and a workpiece; and a lower jet nozzle that supplies machining fluid from below to the machining gap; an upper flow path group having a plurality of parallel bypass flow paths with different flow rates that supply machining fluid to the upper jet nozzle; an upper valve provided in at least one bypass flow path in the upper flow path group for opening and closing the flow path; a lower flow path group having a plurality of parallel bypass flow paths with different flow rates that supply machining fluid to the lower jet nozzle; a lower valve provided in at least one bypass flow path in the lower flow path group for opening and closing the flow path; a jet pump that supplies machining fluid to the upper flow path group and the lower flow path group; a flow rate control unit that controls the flow rate of the jet pump; and a flow rate ratio control unit that individually controls the opening and closing of the upper valve and the lower valve by each valve. [Effects of the Invention]

[0012] In the wire electric discharge machining apparatus according to the present invention, the overall flow rate of the machining fluid supplied to the machining gap is changed by changing the frequency of the jet pump using an inverter controlled by the flow rate control unit.

[0013] An upper flow path group, which is a path for supplying machining fluid to the upper jet nozzle, is provided with multiple bypass flow paths with different flow rates in parallel. At least one of the multiple bypass paths in the upper flow path group is provided with an upper valve that opens and closes the path. Similarly, a lower flow path group, which is a path for supplying machining fluid to the lower jet nozzle, is provided with multiple bypass flow paths with different flow rates in parallel. At least one of the multiple bypass paths in the lower flow path group is provided with a lower valve that opens and closes the path. Furthermore, a flow rate ratio control unit individually controls the opening and closing of each of the upper and lower valves, thereby responding to changes in the upper and lower machining fluid flow rate ratios for the upper and lower jet nozzles. Preferably, the multiple bypass flow paths with different flow rates have different inner diameters, and the upper flow path group and the lower flow path group each include three bypass flow paths, with the flow rate ratios of the three bypass flow paths being 1:2:3. When such bypass flow paths are provided, the flow rate ratio of the upper and lower jet nozzles can be changed in multiple steps in increments of 1 from the minimum flow rate ratio to a flow rate ratio of 6 by individually controlling the opening and closing of the three bypass flow paths.

[0014] By configuring the wire electric discharge machining apparatus in this way, the flow rate ratio of the machining fluid supplied from the upper jet nozzle and the lower jet nozzle can be changed by combining the opening and closing of the upper valve and the lower valve. At the same time, by changing the flow rate of the jet pump itself, the overall flow rate of the machining fluid supplied from the upper jet nozzle and the lower jet nozzle can also be changed.

[0015] Then, by setting the flow rate and flow rate ratio of the upper and lower jet nozzles according to the machining conditions, and changing the combination of opening and closing of the upper valve and the lower valve according to the settings, and the frequency setting value of the jet pump, an appropriate machining fluid corresponding to the machining conditions is supplied to the machining gap. Preferably, open control is performed, and the combination of opening and closing the upper valve and the lower valve according to the flow rates and flow rate ratios of the upper and lower jet nozzles, as well as the frequency setting value of the jet pump, are stored in advance as a data table and are changed based on the data table. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a schematic diagram of the present embodiment. FIG. [Figure 2] 5 is a schematic diagram of control by a flow rate control unit and a flow rate ratio control unit of the present embodiment. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0017] Various embodiments of the present invention will be described below as examples, and the embodiments shown below can be combined with each other.

[0018] FIG. 1 is a schematic diagram showing how machining fluid F is supplied from a jet pump 3 to a machining gap between a workpiece W and a wire electrode E via an upper jet nozzle 11 and a lower jet nozzle 21 in a wire electric discharge machining apparatus according to this embodiment.

[0019] The jet pump 3 branches and supplies clean machining fluid F to an upper flow path group 10 and a lower flow path group 20. The upper flow path group 10 supplies machining fluid F to an upper jet nozzle 11. Similarly, the lower flow path group 20 supplies machining fluid F to a lower jet nozzle 21.

[0020] The upper flow passage group 10 includes three bypass flow passages and two valves. The three bypass flow paths of the upper flow path group 10 have different flow rates when the inverter frequency of the jet pump 3 is set to the reference frequency of 30 Hz: the upper bypass flow path 111 is 0.5 L / min, the upper bypass flow path 112 is 1.0 L / min, and the upper bypass flow path 113 is 1.5 L / min. In other words, the flow rate ratio between the upper bypass flow path 111, the upper bypass flow path 112, and the upper bypass flow path 113 is 1:2:3. The three bypass flow paths have different inner diameters, which results in different flow rates. The two valves in the upper flow passage group 10 are an upper valve 101 provided in an upper bypass flow passage 111 and an upper valve 102 provided in an upper bypass flow passage 112.

[0021] When the upper valve 101 is open, the upper bypass flow path 111 is open, allowing the machining fluid F to pass through. When the upper valve 101 is closed, the upper bypass flow path 111 is closed, preventing the machining fluid F from passing through. When the upper valve 102 is open, the upper bypass flow path 112 is open, allowing the machining fluid F to pass through. When the upper valve 102 is closed, the upper bypass flow path 112 is closed, preventing the machining fluid F from passing through. The upper bypass flow path 113 is always open and does not have any element for closing the flow path.

[0022] The lower channel group 20 also includes three bypass channels and two valves. The three bypass flow paths of the lower flow path group 20 have different flow rates when the inverter frequency of the jet pump 3 is set to the reference frequency of 30 Hz: the lower bypass flow path 211 has a flow rate of 0.5 L / min, the lower bypass flow path 212 has a flow rate of 1.0 L / min, and the lower bypass flow path 213 has a flow rate of 1.5 L / min. In other words, the flow rate ratio between the lower bypass flow path 211, the lower bypass flow path 212, and the lower bypass flow path 213 is 1:2:3. The three bypass flow paths have different inner diameters, which results in different flow rates. The two valves in the lower flow passage group 20 are a lower valve 201 provided in the lower bypass flow passage 211 and a lower valve 202 provided in the lower bypass flow passage 212.

[0023] When the lower valve 201 is open, the lower bypass flow path 211 is open, allowing the machining fluid F to pass through. When the lower valve 201 is closed, the lower bypass flow path 211 is closed, preventing the machining fluid F from passing through. When the lower valve 202 is open, the lower bypass flow path 212 is open, allowing the machining fluid F to pass through. When the lower valve 202 is closed, the lower bypass flow path 212 is closed, preventing the machining fluid F from passing through. The lower bypass flow path 213 is always open and does not have any element for closing the flow path.

[0024] FIG. 2 is a schematic diagram showing the wire electric discharge machining apparatus of this embodiment in which a flow rate control unit 40 controls the flow rate of the jet pump 3 via an inverter 41, and a flow rate ratio control unit 42 controls the flow rate ratio by opening and closing upper valve 101, upper valve 102, lower valve 201, and lower valve 202.

[0025] The inverter 41 changes the frequency of the jet pump 3. The change in frequency changes the flow rate of the jet pump 3, which in turn changes the amount of machining fluid F supplied to the machining gap by the upper jet nozzle 11 and the lower jet nozzle 21. Based on the range of flow rates of machining fluid jets that are practically required in accordance with settable machining conditions, in this embodiment, the inverter 41 uses a state in which the inverter frequency is 30 Hz as a reference, that is, a range of approximately 20 Hz to 40 Hz as a reference frequency.

[0026] The flow rate control unit 40 changes the frequency setting value of the inverter 41 in accordance with the flow rate of the upper and lower jet nozzles corresponding to the processing conditions.

[0027] The flow rate ratio control unit 42 individually controls the opening and closing of the upper valve 101, the upper valve 102, the lower valve 201 and the lower valve 202 in accordance with the flow rate ratio of the upper and lower jet nozzles corresponding to the processing conditions. By combining the opening and closing of the upper valve 101, the upper valve 102, the lower valve 201 and the lower valve 202, it is possible to change the flow rate ratio of the upper and lower jet nozzles individually in multiple stages.

[0028] Specifically, if the flow rate of the upper jet nozzle 11 is a flow rate ratio of 3 when the upper valve 101 is closed and the upper valve 102 is closed, the flow rate ratio is 4 when the upper valve 101 is open and the upper valve 102 is closed, the flow rate ratio is 5 when the upper valve 101 is closed and the upper valve 102 is open, and the flow rate ratio is 6 when the upper valve 101 is open and the upper valve 102 is open. Similarly, if the flow rate of the lower jet nozzle 21 is set to a flow rate ratio of 3 when the lower valve 201 is closed and the lower valve 202 is closed, the flow rate ratio is 4 when the lower valve 201 is open and the lower valve 202 is closed, the flow rate ratio is 5 when the lower valve 201 is closed and the lower valve 202 is open, and the flow rate ratio is 6 when the lower valve 201 is open and the lower valve 202 is open. Therefore, the flow rate ratio of the upper jet nozzle 11 and the flow rate ratio of the lower jet nozzle 21 can be changed separately within the range of flow rate ratio 3 to 6 in increments of 1.

[0029] Generally, the machining conditions in wire electric discharge machining include, for example, discharge time, discharge pause time, servo reference voltage, feed speed, voltage value, feed speed, etc., but in the wire electric discharge machining device of this embodiment, the machining conditions also include the degree of adhesion between the workpiece W and the upper jet nozzle 11 and the lower jet nozzle 21 (so-called floating machining and step machining). Since the set values ​​of the machining conditions differ for each machining process, the flow rate control unit 40 and the flow rate ratio control unit 42 control the flow rate of the jet pump 3 and the opening and closing of the upper valve 101, the upper valve 102, the lower valve 201, and the lower valve 202 for each machining process. The machining conditions may be changed during machining by so-called adaptive control. For example, when the thickness of the workpiece changes during machining, the initially set machining conditions are changed to correspond to the change in thickness.

[0030] The wire electric discharge machining apparatus of this embodiment is provided with a data table in advance. The data table stores the frequency setting value of inverter 41 and the opening and closing of upper valve 101, upper valve 102, lower valve 201, and lower valve 202 according to the flow rates and flow rate ratios of the upper and lower jet nozzles corresponding to the machining conditions. Based on this data table, flow rate control unit 40 and flow rate ratio control unit 42 control the frequency setting value of inverter 41 and the opening and closing of upper valve 101, upper valve 102, lower valve 201, and lower valve 202. By controlling the flow rate and flow rate ratio based on a data table, it is not necessary to calculate the controls performed by the flow rate control unit 40 and flow rate ratio control unit 42 each time the processing conditions are changed, and it is not necessary to install new sensors to measure the flow rate and flow rate ratio of the upper and lower jet nozzles and perform feedback control.

[0031] Table 1 is a data table for this embodiment. The flow rates of the upper and lower jet nozzles range from 1.0 L / min to 4.0 L / min in increments of 0.5 L / min, and the upper and lower jet nozzle flow rate ratio is 1:1, 1:2, or 2:1. Since it is not required to adjust the flow rate and flow rate ratio of the upper and lower jet nozzles very precisely or over a wide range, it is possible to supply the machining gap with an appropriate amount of machining fluid F that corresponds to the machining conditions even with a relatively large change range of 0.5 L shown in Table 1. Furthermore, in order to adjust the upper and lower machining fluid jets within the change range of 0.5 L shown in Table 1, it is clear that it is only necessary to provide three systems of upper and lower jet nozzles with a flow rate ratio of 1:2:3, and two systems with flow rate ratios of 1 and 2 with valves.

[0032] [Table 1]

[0033] Based on Table 1, only a few examples of control embodiments of the flow rate control unit 40 and the flow rate ratio control unit 42 are shown. In this embodiment, the flow rates and flow rate ratios of the upper and lower jet nozzles are approximate values; for example, 1.5 L / min actually means approximately 1.5 L / min, and the flow rates and flow rate ratios of the upper and lower jet nozzles may not strictly match the actual measured values. Furthermore, the frequency setting value of the inverter 41 in the data table is a value before fine adjustment at the time of installation to account for differences in the wire electric discharge machining device and the jet pump 3. The frequency setting value of the inverter 41 in the data table roughly matches the flow rates of the upper and lower jet nozzles even at the value before fine adjustment, but by performing fine adjustment at the time of installation, it is possible to make the flow rates of the upper and lower jet nozzles more accurate.

[0034] When the upper and lower jet nozzle flow rate ratio is 1:1. When the flow rate of the upper jet nozzle 11 is 1.5 L / min and the flow rate of the lower jet nozzle 21 is 1.5 L / min, the upper valve 101 is closed, the upper valve 102 is closed, the lower valve 201 is closed, the lower valve 202 is closed, and the frequency setting value of the inverter 41 is set to 30 Hz. When the flow rate of the upper jet nozzle 11 is 1.0 L / min and the flow rate of the lower jet nozzle 21 is 1.0 L / min, the upper valve 101 is closed, the upper valve 102 is closed, the lower valve 201 is closed, the lower valve 202 is closed, and the frequency setting value of the inverter 41 is set to 20 Hz.

[0035] Basically, the flow rates of the upper and lower jet nozzles are changed by the frequency setting value of the inverter 41. However, in Table 1, when the frequency setting value of the inverter 41 is kept low or when changing the frequency setting value alone requires an excessive setting that would cause the frequency of the jet pump 3 to exceed 60 Hz, an exceptional combination of opening and closing the upper valve and the lower valve is used. Normally, when the flow rate of the upper jet nozzle 11 is 2.0 L / min and the flow rate of the lower jet nozzle 21 is 2.0 L / min, the upper valve 101 is closed, the upper valve 102 is closed, the lower valve 201 is closed, the lower valve 202 is closed, and the frequency setting value of the inverter 41 is set to 40 Hz. However, in Table 1, in order to keep the frequency setting value low, the upper valve 101 is opened, the upper valve 102 is closed, the lower valve 201 is opened, the lower valve 202 is closed, and the frequency setting value of the inverter 41 is set to 30 Hz. If simply changing the frequency setting would cause the frequency of jet pump 3 to exceed 60 Hz, and the flow rate of upper jet nozzle 11 is 4.0 L / min and the flow rate of lower jet nozzle 21 is 4.0 L / min, then by opening upper valve 101, upper valve 102, lower valve 201, lower valve 202, and setting the frequency setting of inverter 41 to 40 Hz, it is possible to supply water without increasing the frequency of jet pump 3 to 60 Hz. Therefore, the wire electric discharge machining apparatus of this embodiment is more energy efficient.

[0036] When the upper and lower jet nozzle flow rate ratio is 1:2. When the flow rate of the upper jet nozzle 11 is 1.5 L / min and the flow rate of the lower jet nozzle 21 is 3.0 L / min, the upper valve 101 is closed, the upper valve 102 is closed, the lower valve 201 is opened, the lower valve 202 is opened, and the frequency setting value of the inverter 41 is set to 30 Hz. When the flow rate of the upper jet nozzle 11 is 1.0 L / min and the flow rate of the lower jet nozzle 21 is 2.0 L / min, the upper valve 101 is closed, the upper valve 102 is closed, the lower valve 201 is opened, the lower valve 202 is opened, and the frequency setting value of the inverter 41 is set to 20 Hz. When the flow rate of the upper jet nozzle 11 is 2.0 L / min and the flow rate of the lower jet nozzle 21 is 4.0 L / min, the upper valve 101 is closed, the upper valve 102 is closed, the lower valve 201 is opened, the lower valve 202 is opened, and the frequency setting value of the inverter 41 is set to 40 Hz.

[0037] Although the case where the upper and lower jet nozzle flow rate ratio is 1:2 has been described, when the upper and lower jet nozzle flow rate ratio is 2:1, it is sufficient to switch the opening and closing of the valves of the upper flow path group 10 and the lower flow path group 20. Specifically, it is sufficient to switch the opening and closing of the upper valve 101 with the opening and closing of the lower valve 201, and to switch the opening and closing of the upper valve 102 with the opening and closing of the lower valve 202.

[0038] When the upper and lower jet nozzle flow rate ratio is 3:4. When the flow rate of the upper jet nozzle 11 is 1.5 L / min and the flow rate of the lower jet nozzle 21 is 2.0 L / min, the upper valve 101 is closed, the upper valve 102 is closed, the lower valve 201 is opened, the lower valve 202 is closed, and the frequency setting value of the inverter 41 is set to 30 Hz. When the flow rate of the upper jet nozzle 11 is 1.0 L / min and the flow rate of the lower jet nozzle 21 is 1.5 L / min, the upper valve 101 is closed, the upper valve 102 is closed, the lower valve 201 is opened, the lower valve 202 is closed, and the frequency setting value of the inverter 41 is set to 20 Hz.

[0039] Although the case where the upper and lower jet nozzle flow rate ratio is 3:4 has been described, when the upper and lower jet nozzle flow rate ratio is 4:3, it is sufficient to switch the opening and closing of the valves of the upper flow path group 10 and the lower flow path group 20, just as when the upper and lower jet nozzle flow rate ratio is changed from 1:2 to 2:1. Specifically, it is sufficient to switch the opening and closing of the upper valve 101 with the opening and closing of the lower valve 201, and to switch the opening and closing of the upper valve 102 with the opening and closing of the lower valve 202.

[0040] When the upper and lower jet nozzle flow rate ratio is 2:3. When the flow rate of the upper jet nozzle 11 is 2.0 L / min and the flow rate of the lower jet nozzle 21 is 3.0 L / min, the upper valve 101 is opened, the upper valve 102 is closed, the lower valve 201 is opened, the lower valve 202 is opened, and the frequency setting value of the inverter 41 is set to 30 Hz. When the flow rate of the upper jet nozzle 11 is 2.5 L / min and the flow rate of the lower jet nozzle 21 is 4.0 L / min, the upper valve 101 is opened, the upper valve 102 is closed, the lower valve 201 is opened, the lower valve 202 is opened, and the frequency setting value of the inverter 41 is set to 40 Hz.

[0041] Although the case where the upper and lower jet nozzle flow rate ratio is 2:3 has been described, when the upper and lower jet nozzle flow rate ratio is 3:2, it is sufficient to switch the opening and closing of the valves of the upper flow path group 10 and the lower flow path group 20, just as when the upper and lower jet nozzle flow rate ratio is changed from 1:2 to 2:1. Specifically, it is sufficient to switch the opening and closing of the upper valve 101 with the opening and closing of the lower valve 201, and to switch the opening and closing of the upper valve 102 with the opening and closing of the lower valve 202.

[0042] As described above, the flow rate and flow rate ratio of the upper and lower jet nozzles can be automatically controlled, which prevents individual differences and setting errors between operators and reduces the burden on the operator.In addition, since the configuration can be automated relatively easily, the introduction cost can be kept low.

[0043] A combination of a 1:1 upper / lower jet nozzle flow rate ratio and a 1.5 L / min upper / lower jet nozzle flow rate, which are the basic conditions used for so-called close contact machining, is frequently used. Therefore, when the jet pump 3 operates at a reference frequency of 30 Hz, the upper / lower jet nozzle flow rate and flow rate ratio are achieved using only the upper / lower bypass flow paths, which are always open. Therefore, in this embodiment, the upper bypass flow path 113 and the lower bypass flow path 213 do not need to be equipped with valves, which simplifies the overall configuration. However, the upper bypass flow path 113 and the lower bypass flow path 213 may also be equipped with additional valves, allowing the flow rate ratio control unit 42 to control the opening and closing of all bypass flow paths, enabling more precise control.

[0044] In this embodiment, the upper flow path group 10 and the lower flow path group 20 each include three bypass flow paths, but each may include two or more bypass flow paths. For example, two, four, or five bypass flow paths may be used. In this case, one of the bypass flow paths may be always open and not include a valve, or all of the bypass flow paths may be provided with a valve.

[0045] A switching valve may be provided after the jet pump 3 and before the branching of the upper flow path group 10 and the lower flow path group 20, and a rough machining flow path that is opened and closed by the switching valve and supplies machining fluid F to the upper jet nozzle 11 and the lower jet nozzle 21 during rough machining may be provided. During rough machining, the switching valve closes the flow paths on the upper flow path group 10 and the lower flow path group 20 side, opens the flow path on the rough machining side, and supplies machining fluid F from the jet pump 3. During finish machining, the switching valve closes the flow path on the rough machining side, opens the flow paths on the upper flow path group 10 and the lower flow path group 20 side, and supplies machining fluid F from the jet pump 3 to the upper flow path group 10 and the lower flow path group 20.

[0046] The present invention is not limited to the configuration of the embodiment, and various modifications and applications are possible within the scope of the technical concept of the present invention. [Explanation of symbols]

[0047] Upper channel group 10 Upper jet nozzle 11 Upper valve 101 Upper valve 102 Upper bypass channel 111 Upper bypass channel 112 Upper bypass channel 113 Lower channel group 20 Downward jet nozzle 21 Lower valve 201 Lower valve 202 Lower bypass channel 211 Lower bypass channel 212 Lower bypass channel 213 Jet pump 3 Flow control unit 40 Inverter 41 Flow ratio control section 42 Work W Wire electrode E Processing fluid F

Claims

1. an upper jet nozzle that supplies a machining fluid from above into a machining gap formed between an electrode and a workpiece, and a lower jet nozzle that supplies the machining fluid from below into the machining gap; an upper flow passage group having a plurality of bypass flow passages with different flow rates arranged in parallel, which supply the machining fluid to the upper jet nozzle; an upper valve provided in at least one bypass flow path in the upper flow path group for opening and closing the flow path; a lower flow passage group including a plurality of bypass flow passages arranged in parallel and having different flow rates, which supply the machining fluid to the lower jet nozzle; a lower valve provided in at least one bypass flow path among the lower flow path group for opening and closing the flow path; a jet pump that supplies the machining fluid to the upper flow path group and the lower flow path group; a flow rate control unit for controlling the flow rate of the jet pump; a flow rate ratio control unit that controls the opening and closing of the upper valve and the lower valve individually for each valve.

2. The wire electric discharge machining apparatus according to claim 1 , wherein the flow rate control unit controls the flow rate of the jet pump by controlling a frequency of an inverter.

3. The wire electric discharge machining device according to claim 1 , wherein the bypass flow passages of the upper flow passage group and the bypass flow passages of the lower flow passage group have different inner diameters, thereby causing different flow rates.

4. one of the bypass flow paths of the upper flow path group does not have the upper valve, and the remaining bypass flow paths each have the upper valve; 2. The wire electric discharge machining apparatus according to claim 1, wherein one of the bypass flow paths of the lower flow path group does not have the lower valve, and the remaining bypass flow paths each have the lower valve.

5. The wire electric discharge machining apparatus according to claim 1 , wherein the upper flow passage group and the lower flow passage group each include three bypass flow passages.

6. 6. The wire electric discharge machining apparatus according to claim 5, wherein the flow rate ratio of each of the three bypass flow paths is 1:2:

3.

7. 6. The wire electric discharge machining apparatus according to claim 5, wherein one of the three bypass flow paths does not have the upper valve or the lower valve, and the remaining two paths are each provided with the upper valve or the lower valve, respectively.

8. 2. The wire electric discharge machining device according to claim 1, wherein the flow rate control unit and the flow rate ratio control unit are controlled by previously preparing a database table according to the flow rate ratios and flow rate conditions of the upper jet nozzle and the lower jet nozzle.

9. The wire electric discharge machining apparatus according to claim 1 , wherein the flow rate control unit and the flow rate ratio control unit perform open control.

10. an upper jet nozzle that supplies a machining fluid from above into a machining gap formed between an electrode and a workpiece, and a lower jet nozzle that supplies the machining fluid from below into the machining gap; an upper flow passage group having a plurality of bypass flow passages with different flow rates arranged in parallel, which supply the machining fluid to the upper jet nozzle; an upper valve provided in at least one bypass flow path in the upper flow path group for opening and closing the flow path; a lower flow passage group including a plurality of bypass flow passages arranged in parallel and having different flow rates, which supply the machining fluid to the lower jet nozzle; a lower valve provided in at least one bypass flow path among the lower flow path group for opening and closing the flow path; a jet pump that supplies the machining fluid to the upper flow path group and the lower flow path group; a flow rate control unit for controlling the flow rate of the jet pump; a flow rate ratio control unit that controls the opening and closing of the upper valve and the lower valve individually, A wire electric discharge machining method comprising: a step in which the flow rate control unit controls the flow rate of the jet pump in accordance with machining conditions of wire electric discharge machining; and a step in which the flow rate ratio control unit controls opening and closing of the upper valve and the lower valve.

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