JP2004230517A - Electrical spark drill and forming method of hole by electrical spark - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To create a desired hole on a work in high precision and in a short period of time. <P>SOLUTION: At least one of voltage applied between an electrode and the work, electrical conductivity of liquid supplied between the electrode and the work in the middle of drilling the hole, and a gap distance between the electrode and the work, is controlled on an electric spark drill. Operation or quality of drilling of the hole is improved by control including operation of applied voltage and a contact stopping function, control including use of a consumable electrode, and control to enclose actuation of a guide mechanism. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an electric discharge machine (EDM) and more particularly to an electric spark drill and a method for drilling holes with an electric spark.
[0002]
[Prior art]
There are at least two types of electrical discharge machines (EDMs) that use electrodes to form holes in a workpiece. Wire cutting machine and spark drill machine. In the category of spark drilling machines, liquid intervenes between the electrode and the workpiece. In a conventional spark drill, oil or kerosene oil is used as a liquid. However, these systems are more likely to ignite flammable oils or kerosene oils with electric sparks.
[0003]
For the second type of spark drill, water is used as the liquid. That is, in the conventional spark drill, low conductivity water having a specific resistance of about 100,000 to 1,000,000 cmΩ is used by using a high voltage about five times the arc discharge voltage. However, the applied high voltage wears the electrodes, sometimes leading to abnormal wear of the electrodes, both of which are problems.
[0004]
FIG. 1 is an illustration of a conventional electric spark drill for drilling one or more holes in a workpiece 10 with electrodes 12. The voltage Vg is applied between the electrode 12 and the gantry base 14 (supporting the workpiece 10).
The applied voltage Vg and the low-conductivity liquid 18 supplied from the working fluid tank 20 are set so as to cause arc discharge in the gap 16 ′ between the electrode 12 and the work 10 in order to machine a hole in the work 10. It is.
The voltage Vg of the gap 16 'and the conductivity of the liquid 18 result in a combination of parameters that include the gap, a desirable "arcing condition" and two undesirable conditions "open gap" or "short gap."
Liquid 18 is supplied to gaps 16 and 16 ′ through pump 22. Ideally, if an arc discharge only occurs at the tip gap 16 'of the electrode 12, the hole in the workpiece 10 will be efficiently machined. Further, it is not desirable to perform arc discharge in the side gap 16 of the electrode 12, and the processing efficiency and speed of the workpiece 10 are reduced.
The liquid 18 is typically deionized pure water having a conductivity in the range of 10-1 μS (resistivity 100,000-1,000,000 cmΩ) in conventional systems.
The pump 22 normally supplies the liquid 18 at a pressure of about 50 atm and a flow rate of about 60 to 100 cc / min.
The voltage Vg is supplied using the DC power supply 24, the switching element 26, the current limiting resistor 28, and the pulse generator 30, and feeds back the amplifier 32, the Z-axis drive amplifier 34, the average voltage controller 36, the reference voltage Vr, and the gap state. The gap control circuit is configured by the inter-electrode voltage vg ′ for the purpose. Normally, the DC power supply 24 supplies a voltage on the order of four to six times the arc discharge voltage Va.
[0005]
Pump 22 supplies liquid 18 to high pressure joint 23. The amplifier 34 supplies a voltage to the motor Mz. The motor Mz controls the Z-axis position of the electrode as shown in FIG. The motor Mc controls the rotation of the electrode 12. Voltage Vg is provided between the poles through brush contact 38.
[0006]
When the gap voltage Vg reaches a preset voltage, an electric spark or arc is formed in the gap 16 '. As a result, the arc energy is transferred from the electrode 12 to the workpiece 10 and remains there, causing a high-temperature explosion on the workpiece 10, resulting in the surface of the workpiece 10 being decomposed, usually melted and dispersed and re-solidified. It remains in the gap 16 'as a processing tip.
Further, the chip can be removed from the gap 16 ′ by the pumping action of the liquid 18 due to the periodic “jump up and down movement” of the electrode 12.
[0007]
FIG. 2 illustrates the operation of the conventional electric spark drill illustrated in FIG. The peak voltage Vp is essentially equal to the gap open voltage and is the voltage required to form an open circuit in the gap 16 '. The width of application of the peak voltage can be obtained by performing the gap servo control so that the average voltage Vm becomes a constant value. The arc voltage Va is a spark voltage of the gap 16 'generated when the workpiece 10 is machined to form a hole required by the electrode 12.
[0008]
FIG. 3 illustrates in detail the relationship between electrode 12 and gaps 16 and 16 '. 3, the liquid 18 passes through the hole 13 inside the electrode 12, as more clearly illustrated. In addition, the applied voltage and the liquid 18 generate an arc discharge in the tip gap 16 ′ for forming a through hole in the workpiece 10. However, if the conductivity, open circuit voltage, and gap size are not properly selected, arcing can occur in gap 16 and is undesirable.
The arc discharge in the gap 16 causes the electrode 12 to wear abnormally. Further, in the case of a voltage as high as 4 to 6 times the arc discharge voltage, the remaining portion (stock portion 11) is formed by the tapered shape of the tip of the electrode 12 caused by the wear of the electrode 12 as illustrated in FIG. I can do it.
[0009]
When the electrode 12 has completely penetrated the workpiece 10 and exits on the opposite side, the liquid 18 cannot remain in the gap 16 '. This is because the liquid 18 comes out of the through-hole and air discharge occurs in the gap 16 '. In this situation, it is very difficult to remove the remaining stock portion 11, and a high penetration speed cannot be maintained.
[0010]
FIG. 4 shows the relationship when the gap 16 'and the peak voltage are twice, three times, four times and five times the arc discharge voltage Va in the conventional method.
A typical arc discharge voltage Va is 17-20 volts, and the curves in the graph of FIG. 4 essentially show the average voltage and gap distance at gap 16 '.
As illustrated in FIGS. 1 and 2, the average voltage controller 36 controls the distance of the gap 16 'by controlling the average voltage as shown in FIG.
Control near the arc discharge voltage Va shown in the region 40 of FIG. 4 is extremely difficult as a result because the voltage may be too low.
[0011]
FIG. 5 shows the difficulty of the control in the area 40. FIG. 6 shows a relationship between the processing speed W and the processing current Ig shown in FIG. 5 and a curve in the arrangement of FIG. 1 when the average voltage is a function parameter and the DC power supply 24 is a high voltage.
FIG. 5 illustrates that the W curve clearly changes sharply near Va, and control near the arc discharge voltage Va is extremely difficult or impossible with the arrangement of FIG. It indicates that there is.
That is, it is difficult to determine the normal arc discharge, the open state, and the short circuit state in the gap 16 ′ in the steep change region of the machining speed curve W.
That is, as a result of the conventional control system in which the peak voltage Vp as shown in FIG. 1 is a high voltage such as 2 Va, 3 Va, 4 Va or 5 Va.
[0012]
In the operation of the electric spark drill as described above, the electrode 12 faces the workpiece 10 via the gap 16 ′ to perform processing. That is, a drilling liquid (liquid 18) is supplied to the gap 16 'to cause electrical discharge, and as a result processing is performed. Also, if the electric spark drill device is used for penetrating the workpiece 10 or used for trimming mold processing, a more accurate configuration will be required.
[0013]
[Problems to be solved by the invention]
As a result, this operation is also useful for forming various metals and molds. However, the conventional system illustrated in FIG. 1 has some other deficiencies. First, the conventional method of forming a hole in the workpiece 10 using an electric spark drill automatically creates The moment when the electrode 12 penetrates the workpiece 10 cannot be detected. Until now, it has been necessary for an operator to monitor the detection of penetration by the electrode 12.
[0014]
Therefore, after the hole is formed in the workpiece 10, the current is still supplied to the electrode 12 to continue the electric spark drilling operation. As a result, the nominal time for drilling increases and the sides are over machined. That is, the dimensional accuracy of the hole is considerably reduced. As described above, the operator had to perform cumbersome monitoring operations until the drilling operation was completed in order to detect when the electrode penetrated, thereby reducing work efficiency. .
[0015]
The conventional electric spark drill device is particularly disadvantageous when the hole of the workpiece 10 after the completion of the penetration is formed by the thin tube-shaped electrode 12. After the processing of the electrode 12 on the workpiece 10, the feeding and rotation of the electrode 12 causes the electrode tube to vibrate out of alignment. After the processing of the workpiece 10 has progressed, the electrode tube does not advance in a straight line, and as a result, the accuracy of the formed through hole deteriorates.
[0016]
In addition, since the polarities of the electrode 12 and the workpiece 10 are opposite to those of normal electric discharge machining, there is a disadvantage in the conventional electric spark drill. Since the workpiece 10 has a positive polarity and the electrode 12 has a negative polarity, ions move from the workpiece 10 to the electrode 12 as a result (elution of metal cations). The electrochemical erosion due to the ion transfer is a problem in the sense that the workpiece 10 is eroded.
[0017]
Conventional electric spark drills have further disadvantages. That is, the electrode 12 is usually very thin and easily broken or deformed due to its small inner and outer diameters, and the use of this electrode 12 impairs the quality of the hole to be machined in the workpiece 10.
[0018]
[Means for Solving the Problems]
The present invention is directed to several embodiments of the electric spark drill and the method of drilling a workpiece. During drilling, a voltage is applied to the electrodes and controlled to create a through-hole required by the workpiece, with the electrode and the workpiece facing each other with a gap through a liquid of appropriate conductivity. Things.
[0019]
As an embodiment of the present invention for drilling, the voltage applied to the electrode is a function of the arc discharge voltage and involves the electrical conductivity of the liquid between the electrode and the workpiece and the gap between the electrode and the workpiece. That is. At least one embodiment of the invention is characterized in that the voltage applied to the electrodes is equal to the arc discharge voltage or ranges up to twice the arc discharge voltage.
[0020]
Another specific example of the present invention relates to an average voltage applied to the electrodes, wherein the average voltage is about 0.5 to 0.8 arc discharge voltage.
[0021]
Yet another embodiment of the present invention is that the liquid is a high conductivity liquid. As a specific example of the present invention, the high conductivity liquid has a specific resistivity (conductivity of 167 to 100 μS) of about 6000 to 10000 cmΩ.
[0022]
As yet another embodiment, the present invention is directed to an electric spark drill and a method for drilling the required through-holes, but the servo of the gap between the electrodes measures the voltage applied to the electrode, and the gap between the electrode and the workpiece is measured. This is achieved by appropriately controlling the gap.
[0023]
In yet another embodiment, the present invention is directed to an electric spark drill and a method for drilling the required through-holes, wherein the controller applies a voltage to the electrodes to a liquid supplied between the electrodes and the workpiece. Is controlled in accordance with the electrical conductivity of the substrate.
[0024]
In yet another embodiment, the present invention is directed to an electric spark drill and a method of drilling the required through-holes, but wherein a controller is provided between the electrode and the workpiece to ensure proper arcing at the gap. The electric conductivity of the provided liquid is measured, and a liquid having a proper conductivity is supplied and controlled so that the conductivity becomes appropriate as the conductivity increases or decreases.
[0025]
In yet another embodiment, the invention features an electric spark drill and a method for drilling the required through-holes, wherein contact stop after penetration. The fact that the electrode has completely penetrated the workpiece and has been completely removed is detected by contact of the electrode with an element such as a contact plate.
When the electrode touches an element such as a contact plate by the detection circuit, an electrode feed stop signal is generated, and further progress of the electrode can be stopped.
[0026]
As yet another specific example, the present invention utilizes a sacrificial electrode in an electric spark drill and method for drilling the required through-holes so that metal cations can be prevented from eluting from the workpiece to the electrode. It is characterized by. Instead of eluting metal ions from the workpiece, the cations move from the positive polarity sacrificial electrode to the negative polarity electrode.
[0027]
As yet another specific example, the present invention is an electric spark drill and a method for drilling a desired hole, wherein the rotation of the electrode is detected by the configuration of the guide. If the electrode makes an eccentric rotation, the electrode touches another component of the guide. These components constitute a circuit for controlling a signal for stopping the electrode feeding motor.
[0028]
BEST MODE FOR CARRYING OUT THE INVENTION
What is shown in FIG. 6 is an exemplary illustration of the present invention. The electric spark drill of FIG. 6, which is illustrative of the present invention, is very similar to the conventional electric spark drill illustrated in FIG. 1, and accordingly, like numerals and similar elements and descriptions are omitted here. The difference between the embodiment of FIG. 6 according to the present invention and the conventional electric spark drill shown in FIG. 1 is the electric conductivity of the liquid 118 in the tank 20 of the present invention. The electric conductivity of the liquid 118 used in the present invention shown in FIG. 6 is used in the range of 167 to 100 μS (specific resistance 6000 to 10000 cmΩ).
Standard city tap water also corresponds to such a high-conductivity liquid. This is not as expensive as the pure deionized water 18 utilized in the conventional electric spark drill of FIG. Further, the use of a high conductivity liquid 118 allows the electric spark drill of FIG. 6 to operate at a voltage much lower than the peak voltage of the conventional electric spark drill shown in FIG. As a result, in the embodiment shown in FIG. 6, a DC power supply 124 having a much lower voltage than that of the conventional machine is used.
[0029]
Further, the use of a low peak voltage in this embodiment of the present invention is effective in reducing the wear of the electrodes 12, as illustrated in FIG. In this embodiment of the invention, because of the low peak voltage, arcing does not occur in the gap 16, but only in the controlled gap 16 ', so that no stock 11 remains and a better through hole is created. Made.
[0030]
Further, since no arc discharge occurs in the gap 16, the electrode 12 is more evenly worn. Because of the low peak open-circuit voltage, in the case of the specific example of FIG. 6, processing is performed with a gap 16 ′ smaller than the gap 16 illustrated in FIG. Since the peak open voltage is low as a final plan, this performance can be further improved by coating the electrode 12 with enamel or paint. Such an enamel or paint 17 was easily discharged and removed by a high voltage when used in the conventional electric spark drill of FIG. 1 and had no effect.
[0031]
FIG. 8 illustrates a graph of the embodiment of FIG. 6 similar to the graph of FIG. 4 in connection with FIG. As clearly illustrated by FIG. 8, when a higher conductivity liquid 118 is utilized, the electric spark drill can be processed at a low voltage that is close to the arc discharge voltage. This low voltage results in less wear of the electrodes and allows more desirable through holes in the workpiece 10. The two curves in FIG. 8 are illustrative for liquids in two different conductivity ranges, 200-100 μS (resistivity 5000-10000 cmΩ) and 5-1 μS (resistivity 20000-10000 cmΩ).
[0032]
FIG. 9 is a comparison between the processing speed W and the processing current Ig of the conventional electric drill illustrated in FIG. 1 and the processing speed W and the processing current Ig in the specific example illustrated in FIG. In FIG. 9, W1 and Ig1 correspond to the conventional electric spark drill illustrated in FIG. 1, and W2 and Ig2 correspond to the embodiment of the present invention illustrated in FIG.
[0033]
As illustrated by the curve curve W2 of the graph, for the combined low voltage / high conductivity application of the embodiment of FIG. 6, providing a wider operating range in processing than the conventional electric spark drill of FIG. Can be. The low voltage in the low voltage / high conductivity combination application of the embodiment of FIG. 6 also allows for control at an average voltage very close to the arc discharge voltage Va. In the specific example of FIG. 6, FIG. 9 shows that even if the average voltage is reduced to half of the arc discharge voltage Va, the processing can be controlled without becoming unstable or uncontrollable.
[0034]
FIG. 10 illustrates another embodiment of the present invention, where a servo circuit 50 and a servo amplifier 51 are used to control the voltage provided to the electrode feed motor Mz. In the specific example of FIG. 10, the voltage of the gap 16 ′ during the processing is extracted, and the servo 50 controls “forward”, “stop”, and “reverse in reverse”.
[0035]
FIG. 11 shows a waveform in the specific example of FIG. Vg is a pure gap voltage which is not affected by the inductance or stray capacitance of the electrode, Ig is a gap current, and Vopen and Vshort are voltages generated in the gap 16 '. Cp is a control pulse (check pulse). The control pulse is generated from the pulse generator 30. The Cp is generated at the end of the off time of the switching element 26. The switching element 26 is driven by the pulse generator 30.
The servo circuit 50 always shows the state of the servo voltage Vservo. The Vg, Vopen, and Vshort waveforms always indicate whether the gap gap is open, short (short), or normal. If the gap voltage is lower than Vshort, the gap state is a short-circuit state. If the voltage is higher than the Vopen voltage, the gap state is an open state. If there is a voltage waveform between Vopen and Vshort, the gap state is a normal arc discharge state. Cp is a pulse that is sampled at each point in this waveform form so that the servo operation causes the system to transition to a normal arcing state.
[0036]
FIG. 12 is a specific example of the servo circuit 50 of FIG. This circuit is exemplary only, and other circuit cases as known in ordinary circuit technology may be utilized.
[0037]
FIG. 13 shows another embodiment of the present invention, in which the inter-electrode open-circuit voltage is controlled according to a change in the electric conductivity of the liquid 118. In the embodiment illustrated in FIG. 13, the electrodes 12 are processed in the workpiece 10 in the processing vessel 52 and the waste liquid 54 (highly conductive liquid 118 and waste sludge from the processing) is placed in a suitable container structure. And particles produced as a result of processing) are discharged.
Waste liquid 54 is sent to tank 20 ′, which maintains the same conductivity as liquid 118 in tank 20. The waste liquid 54 removes particles through the filter 156 and is sent to the tank 20 through the pump 122 as the filtered liquid 44.
[0038]
Sensor 158 detects the conductivity of liquid 118. (Usually, the conductivity can be detected by measuring the alternating current. It is also possible to measure the conductivity by other measurement methods).
The output of the sensor 158 is supplied to a voltage controller 160 that controls the open voltage of the applied voltage Vg supplied to the electrode 12 and the workpiece 10 according to the conductivity of the liquid 118 in the tank 20.
In this manner, the voltage can be increased or decreased depending on whether the conductivity of the liquid 118 is decreasing or increasing.
[0039]
FIG. 14 is an exemplary implementation of the open voltage controller 160 of FIG. This implementation can of course be realized by various known techniques.
[0040]
FIG. 15 is another specific embodiment of the present invention that utilizes electromagnetic valve control to control an electric spark drill.
The embodiment of FIG. 15 is similar to the embodiment of FIG. 13, in which a third tank 20 "is filled with pure water or deionized water, and the pure water or deionized water 218 is stored in a third tank 20". The water is supplied from the tank 20 'to the tank 20 by the pump 222 according to the state of the valve 60. The valve 60 is opened and closed by an electromagnetic valve controller 260.
The solenoid valve controller 260 operates on the output of the sensor 158 measuring the conductivity of the liquid 118. If the conductivity is too high, solenoid valve controller 260 opens valve 60 and deionized water is injected from tank 20 ′ into tank 20 to reduce the conductivity of liquid 118. In this different manner, essentially the same operation is performed in the embodiment illustrated in FIG. 15, as in the embodiment illustrated in FIG.
[0041]
FIG. 16 shows a specific embodiment of the electromagnetic valve controller 260 shown in FIG. The electromagnetic valve controller 260 receives the current signal Is (indicating the conductivity of the liquid 118) from the sensor 158, and opens and closes the valve 60 to reduce the conductivity of the liquid 118 with deionized water or pure water 218. A signal is generated to control whether the liquid is supplied from tank 20 'to tank 20.
It will be appreciated that the exemplary embodiment illustrated in FIG. 16 can be implemented with various known techniques.
[0042]
FIG. 17 shows still another embodiment of the present invention. The embodiment of FIG. 17 is illustrative of the invention with two additional features. Although these two features are described together, it should be noted that they are used separately or in combination with other features.
The first feature in FIG. 17 is contact stop. A contact 12 forms a closed circuit by contact, and when the electrode 12 completely passes through the workpiece 10, generates a signal for stopping the electrode feed and stops the drill operation.
In the specific embodiment of FIG. 17, the electrode 12 comes into contact with the contact detection plate 70. In the contact stop circuit 72 (also an exemplary example), the contact detection plate 70 and the electrode 12 form a contact detection circuit. When the electrode 12 contacts the contact detection plate 70, a signal is generated to stop the Mz motor. Further, in order to avoid a short circuit between the contact detection plate 70 and the surface plate of the electric spark drill, it is insulated by a rubber sheet 74 or the like.
[0043]
A second feature of the embodiment illustrated in FIG. 17 is the use of a sacrificial electrode 80. In a normal use operation, the electrode 12 is set to a negative polarity, and the workpiece 10 is set to a positive polarity. Due to the combination of these polarities, positive metal ions from the surface of the workpiece 10 having a positive polarity are electrolytically transferred to the electrode 12 having a negative polarity, thereby causing a kind of corrosion. In fact, if the workpiece 10 is a compacted powder alloy, such as tungsten carbide, having a binder such as cobalt, such workpiece 10 is easily electrolytically eroded. This is due to the electrolytic transition of the metal positive ions from the workpiece 10 to the electrode 12.
[0044]
To reduce the probability of ion migration from the workpiece 10 to the electrode 12, a sacrificial electrode 80 is provided. The electrode 80 has a positive polarity with a higher voltage than the workpiece 10. As a result, the metal positive ions are eluted from the sacrificial electrode 80 instead of the workpiece 10 being eroded. As an alternative embodiment, the polarities of the electrode 12 and the workpiece 10 can be reversed.
[0045]
In yet another exemplary embodiment of the present invention, illustrated in FIG. 18, the features of the contact stop feature described in FIG. 17 are combined with features of the electrode guide mechanism.
The outer diameter and the inner diameter of the electrode 12, which is an extremely thin tube, are very small, and when this is used, the electrode 12 may vibrate in an out-of-center manner. This is not desirable for machining high quality holes.
As a result, a guide sensor 90 (which substantially encircles the center of the electrode 12 in an annular shape) is provided. When the electrode 12 starts to vibrate excessively, the electrode 12 comes into contact with the guide sensor 90 to form a closed circuit, so that a current It1 is generated. When this current is detected, it indicates that the electrode 12 is touching the guide sensor 90, and the electrode rotating motor Mc is stopped.
[0046]
In the specific example of FIG. 17, the characteristics of the contact stop and the characteristics of the sacrificial electrode are described in combination. Further, FIG. 18 illustrates an example in which the feature of the contact stop and the feature of the electrode guide mechanism are combined.
However, the invention should not be limited to only these combinations. In particular, the features of the contact stop, the features of the electrode guide mechanism and the features of the sacrificial electrode can all be used together in some combinations. Similarly, other combinations are also known as a skill in the art.
[0047]
It should be noted that various features have been described herein. Regarding conductivity and voltage control, these features may be used alone or in combination, but with the described control of parameters and other controls to achieve the desired result. Is natural.
[0048]
Additionally, it should be noted that the other features, namely the sacrificial electrode, contact stop, and guide mechanism described herein, are implemented alone or in combination, or as described above for conductivity and It is effective in combination with all the features such as voltage control.
[0049]
Although the invention has been described in this manner, it will be clear that the description can be varied in many ways.
Such changes are not considered to be a departure from the spirit and scope of the invention, and all changes are expressly included in the claims as a skill in the art.
[0050]
【The invention's effect】
According to the present invention, as described above, drilling can be performed with high accuracy in a short time.
[0051]
[Brief description of the drawings]
FIG. 1 is an illustration of a conventional electric spark drill.
FIG. 2 is a graph showing the relationship between voltage and current of the conventional electric spark drill of FIG.
FIG. 3 shows the electrode 12 of the conventional electric spark drill of FIG. 1 in more detail.
FIG. 4 illustrates how the voltage between contacts is related as a function of peak voltage Vp and gap length.
FIG. 5 is a graph showing the relationship between electrode travel speed and current as a function of average voltage and gap distance.
FIG. 6 illustrates a specific example of the electric spark drill of the present invention.
FIG. 7 is an illustration of the electrodes in FIG.
FIG. 8 shows a relationship between an average voltage and a gap length in FIG. 6;
9 shows the relationship between the electrode traveling speed (processing speed W2) and the current (Ig2) in the specific example shown in FIG. 6, and the electrode traveling speed (processing speed W1) and the current (Ig) in the conventional specific example shown in FIG. Ig1).
FIG. 10 is an illustration of an embodiment of the present invention for properly servo-controlling with applied voltage.
11 is a waveform at the time of control according to the specific example shown in FIG.
FIG. 12 is a more detailed description of a specific example of the servo shown in FIG. 10;
FIG. 13 is another illustrative embodiment of the present invention that performs control of the applied open circuit voltage responsive to the conductivity of the liquid.
14 is a more detailed description of a specific example of the control device for the applied open-circuit voltage shown in FIG. 13;
FIG. 15 is a specific example of an apparatus for controlling a voltage applied to an electromagnetic valve for controlling whether to supply an external low-conductivity liquid based on the conductivity of the liquid when using the low-conductivity liquid.
FIG. 16 is a more detailed description of an embodiment of the electromagnetic valve controller of FIG. 15;
FIG. 17 is another embodiment of the present invention including a sacrificial electrode and a contact stop function.
FIG. 18 shows another embodiment of the present invention in which an electrode guide function and a contact stop function are executed.
[Explanation of symbols]
10 Workpiece
11 Stock Department
12 electrodes
13 holes
14 Mount base
16 gap
16 'controlled gap
17 Enamel or paint
18 Deionized water
20 tank 1
20 'tank 2
20 '' tank 3
22 Pump (P1)
23 High pressure fittings
24 DC power supply
26 Switching element
28 Current limiting resistor (Ro)
30 pulse generator
32 amplifier
34 Z-axis drive amplifier
36 Average voltage controller
38 brushes
44 Filtered liquid
50 Servo circuit
51 Servo amplifier
52 Processing container
54 Waste liquid
60 valve
70 Contact detection plate
72 Contact stop circuit
74 rubber sheet
80 Sacrificial electrode
90 Guide sensor
118 Low conductivity liquid
122 pump (P2)
124 DC power supply (Eo)
156 Filter (F)
158 sensor
160 voltage controller
218 Pure or deionized water
222 pump (P3)
260 solenoid valve controller
Vg applied voltage (inter-electrode voltage)
vg 'Inter-pole feedback voltage
vg Actual detectable voltage between contacts
Vr reference voltage
Mz Z axis drive motor
Mc electrode feeding motor
Vp peak voltage
Vm average voltage
Va arc voltage
Vopen Gap open state detection level voltage generated between gaps 16 '
Vshort gap detection level voltage generated between gaps 16 '
Vservo servo voltage
Induced voltage generated in inductor component of VLo electrode
Inductor component of Lo electrode
Stray capacitance existing between Co electrode and workpiece
Ig Processing current (gap current)
Ig1 Machining current in conventional method
Ig2 Processing current in the present invention
Is current signal
Sensor current when the It1 electrode contacts the workpiece
Sensor current that flows when the It2 electrode contacts the guide sensor
Ip peak current
W Processing progress speed
W1 Conventional processing speed
W2 Processing speed of the present invention
Cp control pulse (check pulse)
Eo DC power supply
EAC AC power supply
Ton energizing time
Toff interruption time

Claims (26)

An electrode for creating an arc in the gap between the workpiece and the electrode, a liquid supply source for supplying a liquid to the gap, a voltage source for applying a voltage to the electrode, the voltage range as At least one control, such as maintaining the voltage, the specific resistivity of the liquid, and the size of the gap for creating a desired hole in the workpiece, to be approximately equal to the arc discharge voltage or up to twice the arc discharge voltage. Spark drill with a controller for. 2. The electric spark drill according to claim 1, wherein the voltage applied by the voltage source is higher in the gap open voltage than the gap average voltage. 2. The electric spark drill according to claim 1, wherein the voltage applied by the voltage source is between 17 and 40 volts. The electric spark drill according to claim 1, wherein the liquid is a high conductivity liquid. 2. The electric spark drill according to claim 1, wherein said liquid has a specific resistivity of 6000 to 10000 cm [Omega] (a conductivity of 167 to 100 [mu] S). The electric spark drill of claim 1, wherein the controller includes a servo control, the servo measuring the gap voltage and adjusting the gap distance of the electrodes by advancing, holding, or reversing. . 7. The servo control of claim 6, wherein the servo control is advanced, held, or reversed in response to a control pulse generated by a pulse generator, which occurs at the end of the off time of the switching element. Electric spark drill. The electric spark drill according to claim 1, wherein the controller is a controller including a voltage controller for controlling a voltage applied to the electrode based on a specific resistivity of the liquid. The electric spark drill according to claim 1, wherein the controller is a controller including a resistivity controller for controlling a resistivity of a liquid. 2. The electric spark drill according to claim 1, wherein the electrode is coated with at least a kind of enamel or paint. The contact stop element is installed to complete a closed circuit when the electrode penetrates the workpiece, and completes the closed circuit and generates a detection signal when the electrode contacts the contact stop element. The electric spark drill according to claim 1, wherein the detector emits a signal, and stops the electrode feed in response to the signal. Providing a sacrificial electrode near the electrode and the workpiece such that the metal cations migrate out of the sacrificial electrode to prevent migration of the metal cation from the workpiece. An electric spark drill according to claim 1. The contact stop guide mechanism completes a closed circuit and generates a detection signal when the electrode contacts the guide mechanism when the electrode vibrates while the electrode is penetrating the workpiece. The electric spark drill according to claim 1, wherein the detector emits a signal and stops the rotation of the electrode in response to the signal. In a configuration in which an arc discharge is created in a gap between an electrode and a workpiece and a liquid is supplied to the gap, a voltage is applied to the electrode, and the voltage range is substantially equal to an arc discharge voltage or an arc. Electric discharge characterized by performing at least one control such as maintaining the voltage, the conductivity of the liquid, and the size of a gap for forming a desired hole in a workpiece, up to twice the discharge voltage. A method of forming holes by sparks. The method for forming a hole by an electric spark according to claim 14, wherein the gap voltage is higher than the average voltage at the applied voltage. 15. The method of claim 14, wherein the applied open circuit voltage is between 17 and 40 volts. The method of claim 14, wherein the liquid is a high conductivity liquid. 15. The method of claim 14, wherein the liquid has a resistivity of 6000-10000 cm [Omega] (a conductivity of 167-100 [mu] S). 15. The method according to claim 14, wherein said control measures the voltage to adjust the gap distance of the electrode by advancing, holding, or reversing the electrode. How to form. 20. The method of claim 19, wherein the control advances, holds, or reverses the electrodes in response to a control pulse generated by the pulse generator, which occurs at the end of the off time of the switching element. . 15. The method of forming a hole with an electric spark according to claim 14, wherein the controller is a controller including a voltage controller for controlling an applied voltage to the electrode based on the conductivity of the liquid. The method of claim 14, wherein the controller is a controller including a conductivity controller for controlling the conductivity of a liquid. 15. The method of claim 14, wherein the electrode is coated with at least some enamel or paint. The contact stop element is installed to complete a closed circuit when the electrode penetrates the workpiece, and completes the closed circuit and generates a detection signal when the electrode contacts the contact stop element. 15. The method of claim 14, wherein the detector emits a signal and stops the electrode feed in response to the signal. Providing a sacrificial electrode near the electrode and the workpiece such that the metal cations migrate out of the sacrificial electrode to prevent migration of the metal cation from the workpiece. A method of forming a hole by the electric spark of claim 14. The contact stop guide mechanism completes a closed circuit when the electrode contacts the guide mechanism when the electrode vibrates while penetrating the workpiece, and generates a detection signal. The method of claim 14, wherein the detector emits a signal and stops the electrode advance in response to the signal.

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