KR20110064502A - Wire electric discharge machine of alternating current power source providing method - Google Patents

Abstract

PURPOSE: A wire electric spark machine using an AC power supply method is provided to transfer working currents to discharge electrodes without energy loss. CONSTITUTION: A wire electric spark machine using an AC power supply method comprises a power supply unit(330), a switching unit(320), a resonance circuit(310), and an amplification circuit(300). The power supply unit supplies DC power. The switching unit is connected to the power supply unit and switches to generate resonance. The resonance circuit is composed of serial and parallel circuits using inductance and capacitance and outputs a minimum discharge current. The amplification circuit is connected to the resonance circuit and amplifies power.

Description

Wire Discharge Machine with AC Power Supply {WIRE ELECTRIC DISCHARGE MACHINE OF ALTERNATING CURRENT POWER SOURCE PROVIDING METHOD}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wire electric discharge machine, and in particular, an alternating current (hereinafter referred to as "AC") that can prevent a voltage drop in a wire electric discharge machine and improve surface quality and processing precision of a workpiece without losing energy of an input power source. '') It is related to a wire electric discharge machine of power supply type.

In general, the electric discharge machine is a device for processing an object by using an electrical action generated when a discharge is generated between two electric discharge electrodes, a total electric discharge machine using a total electrode as a discharge electrode and a wire electric discharge machine using a wire as a discharge electrode. There are various types.

On the other hand, such a discharge processor has a discharge power that can finely control the size of the discharge power applied between the discharge electrodes because the processing speed of the object and the roughness of the processing surface vary depending on the size of the discharge power applied between the discharge electrodes. Control devices must be provided.

Among the electric discharge machines, the wire electric discharge machine usually performs the 4th machining to improve the dimensional accuracy and the surface roughness. Looking at the machining performance of the electric discharge machining, the first machining is roughing and the surface roughness Ra (surface roughness) It is about 3um and the secondary processing is medium cutting and the surface roughness is Ra 2um. The 3rd and 4th machining is the finishing, the surface roughness is about Ra 1um and the surface roughness is about Ra 0.7um during the 4th machining.

As such, the configuration of the wire electric discharge machine in which the surface roughness is processed to about Ra 0.7 μm in the fourth processing may be illustrated in FIG. 1.

Referring to FIG. 1, the variable resistors 100 are connected in parallel and the resistance values are varied to adjust the machining current flowing between the discharge electrodes to match the desired machining surface roughness. At this time, the smaller the processing current flows, the better the surface roughness, so that the larger the resistance value of the variable resistor 100, the smaller the processing current flowing between the discharge electrodes, thereby improving the surface roughness.

However, when the resistance is increased by more than a predetermined value, there is a problem that the voltage applied between the discharge electrodes is small and discharge does not occur. Therefore, the resistance cannot be increased indefinitely and the current cannot be reduced.

Accordingly, when the applied voltage (V) is increased to compensate the voltage drop between the poles due to the variable resistor, the machining current increases, resulting in poor surface finish. As a result, a suitable value of the applied voltage (V) and the variable resistance value is found. The maximum value of the current limiting resistor is about 100 Ω. When the applied voltage is 80 V, the current flowing between the discharge electrodes is about 0.8 A.

As such, when the current flowing between the discharge electrodes is about 0.8A, the surface roughness is the maximum Ra 0.7um level.

As shown in FIG. 1, a direct current flows in a direction in which the current flowing between the discharge electrodes flows in the direction of the wire 104 in the object 103 or in the direction of the object 103 in the wire 104, that is, in one direction. Current) It is called power supply method.

However, as the technology for improving the surface roughness was developed, a circuit was developed such that the fourth processing surface roughness was less than Ra 0.3um, which is smaller than Ra 0.7um.

The wire electric discharge machining machine to make the fourth processing surface roughness Ra 0.3um or less may be illustrated in FIG. 2.

2, the configuration of the variable resistor between the discharge electrodes is removed, and the ring core inductance 200 is inserted. In addition, the DC input power was switched to 1 MHz using a MOSFET (Tr) to limit the ON time of the power applied between the discharge electrodes to 0.5 us.

In this way, the amount of current flowing between the discharge electrodes is limited, the power supply voltage (V) is changed, and the processing current is varied to enable processing for materials of various thicknesses, and the fourth processing surface roughness is Rmax 0.8 ~ 2.5um ( In the case of Ra, about Ra 0.2 ~ 0.3um).

However, when the ring core 200 is used as shown in FIG. 2, the energy of the input power is actually used for only about 10%, and the remaining 90% of the energy is lost as heat in the ring core 200. there was. Therefore, in order to cool the heat of the ring core 200, the ring core has to be manufactured in a water-cooled structure.

Accordingly, the present invention is to solve the problems described above to prevent the voltage drop in the wire electric discharge machine, to provide a wire electric discharge machine that can improve the surface quality and processing precision of the workpiece without losing energy of the input power source do.

The wire discharge processing machine according to the present invention for this purpose, the power supply unit 330 for supplying DC power, the switching unit is connected to the power supply unit 330, switching to generate a resonance at a predetermined resonance frequency in the resonance circuit 310 ( 320, a resonant circuit 310 connected to the switching unit 320, and configured as a series-parallel circuit using inductance and capacitance, for outputting a minimum discharge current at the predetermined resonant frequency, and the resonant circuit 310. And an amplifying circuit 300 connected to the AC power supply to a discharge electrode 341 and 351 for processing the object 340 by amplifying the AC power by a predetermined size, wherein the switching circuit 320 includes: The resonant circuit 310 and the amplifying circuit 300 may be used to convert the DC power supplied from the power supply unit 330 into AC power to be supplied between the discharge electrodes 341 and 351.

In addition, according to an example of the present invention, the switching unit 320 is characterized in that for generating the resonant frequency used in the resonant circuit 310 through the switching.

In addition, according to an example of the present invention, the power supply unit 330 may be configured as a variable power source to select an applied voltage according to the type and thickness of the object to be processed 340.

The wire discharge processing machine according to the present invention as described above is provided with a resonant type amplifier circuit for generating an alternating frequency to improve the surface roughness of the object to be processed and does not use a resistance configuration as in the conventional wire discharge processing machine problems that occurred The problem of voltage drop caused by phosphorus resistance can be solved.

In addition, it is possible to solve the energy loss problem caused by the use of the ring core by switching to a predetermined resonance frequency in order to deliver the maximum processing current to the discharge electrode without energy loss.

Further, by allowing the applied voltage value to be selected within a predetermined range, it is possible to generate suitable processing conditions according to the type and thickness of the material to be processed, thereby achieving the surface roughness of a desired dimension.

Hereinafter, with reference to the accompanying drawings to be described in detail with respect to the wire electric discharge machine according to a preferred embodiment of the present invention.

In the present invention, the object to be processed is connected to the discharge electrode on one side of the discharge electrode, the direction of the current flowing between the discharge electrode in the wire discharge machine consisting of a wire to the other side discharge electrode alternately in the direction of the wire on the object and the direction of the object on the wire It implements a wire discharge machine of AC power supply system that is changed over and over.

3 is a block diagram showing a wire discharge processing machine of the AC power supply method according to an embodiment of the present invention. Referring to FIG. 3, the wire discharge processor of the AC power supply method includes a power supply unit 330, a switching circuit 320, a known circuit 310, an amplification circuit 300, and a discharge electrode 351 on one side of the discharge electrode 351. Is connected, and the object to be processed 340 to be processed is connected to the discharge electrode 341 on the other side.

The switching circuit 320 is connected to the power supply unit 330, and switches so that resonance occurs at a predetermined resonance frequency in the resonance circuit 310. At this time, in the embodiment of the present invention, the resonant frequency may be set to a frequency enough to output the minimum discharge current from the resonant circuit 310. The ideal value may be 1 MHz.

The resonant circuit 310 is connected to the switching unit 320, consists of a series-parallel circuit using inductance and capacitance, the resonance occurs at a predetermined resonant frequency by the operation of the switching circuit 320, at the generated resonant frequency Output the minimum discharge current.

The amplifying circuit 300 is connected to the resonant circuit 310, and amplifies the AC power by a predetermined size to supply the discharge electrodes 341 and 351 for processing the object 340.

The DC power supplied from the power supply unit 330 is converted into AC power using the switching circuit 320, the resonance circuit 310, and the amplification circuit 300, and is supplied between the discharge electrodes 341 and 351. Accordingly, the current between the discharge electrodes 341 and 351 is supplied by an AC power supply method in which current flows alternately from the object 340 to the wire 351 and then from the wire 351 to the object 340. .

When the AC power is supplied between the discharge electrodes 341 and 351 in this manner, the processing OFF time required for the insulation recovery can be greatly reduced, and processing with a high frequency power source is possible.

A rough function relationship between the processing current applied to the discharge electrodes 341 and 351 and the resonance frequency may be expressed by Equation 1 below.

In the present invention, since the variable resistor configuration is not used, the value of the resistor R becomes zero, so the current is determined by the inductance L, the capacitance C, and the applied voltage V. The circuit is designed such that a weak processing current with a maximum current of 1 A or less is transmitted to the discharge electrodes 220 and 230 using a series-parallel resonance circuit 310 using inductance L and capacitance C. At this time, the resonant frequency is to use a resonant frequency of the processing current is 1A or less.

Since the wire electric discharge machine of the present invention does not use a resistor, it is possible to solve the problem of voltage drop caused by the use of a resistor as in the related art.

In addition, since the inductance L and the capacitance C values of the resonant circuit 310 are fixed in the wire electric discharge machine of the present invention, the processing current value is determined by the applied voltage V of the power supply unit 330.

In addition, in the present invention, it is important to switch to the resonant frequency in order to transfer the processing current to the maximum without loss of energy, and preferably to the resonant frequency of 1Mhz. However, the size of the resonance frequency is not limited to 1 Mhz, and the resonance frequency is designed to occur so that the processing current may have a value of 1 A or less.

By doing so, the present invention can solve the energy loss problem, which is a problem due to high energy efficiency in the conventional wire electric discharge machine. In addition, when switching the resonance frequency to 1Mhz as described above, the power consumption is about 50W, the surface roughness (Ra) of the object to be processed 340 can achieve a fourth-order surface roughness of 0.2 ~ 0.3um.

Wire electric discharge machine should be able to process a variety of material types and thickness for this purpose can be combined with the two circuit elements of the wire electric discharge machine according to the present invention can create a processing condition suitable for the type and thickness of the material.

That is, the applied voltage V applied from the power supply unit 330 may be adjusted according to the type and thickness of the object 340 to be processed.

For example, the applied voltage values may be set to 16 levels in 10V units in the range of 50 to 200V voltage as shown in Table 1 below.

level Voltage value level Voltage value One 50 V 9 130 V 2 60 V 10 140 V 3 70 V 11 150 V 4 80 V 12 160 V 5 90 V 13 170 V 6 100 V 14 180 V 7 110 V 15 190 V 8 120 V 16 200 V

That is, depending on the type and thickness of the object to be processed, one of the 16 levels defined in Table 1 may be used.

After the roughing (primary) processing and the medium cutting (secondary) processing is completed, the third processing, which is the finishing process can be processed using a wire electric discharge machine according to an embodiment of the present invention.

Since the processing speed varies according to the thickness of the object to be processed, if the applied voltage is changed according to the thickness and the third process is performed, it can be processed according to various material types and thicknesses.

For example, in the case of 40mm steel material, if the 3rd processing is applied with 100V and the 4th processing is applied with 50V, the surface roughness of the processed object is less than Ra 0.3um. You can get it.

In the wire resonator according to the embodiment of the present invention, a surface roughness Ra of 0.3 μm or less can be achieved by adding a resonance type amplifying circuit for generating AC high frequency to improve surface roughness.

In the above, the specific Example of this invention was described above. However, the spirit and scope of the present invention is not limited to these specific embodiments, and various modifications and variations can be made without departing from the spirit of the present invention. Those who have it will understand.

Therefore, since the embodiments described above are provided to completely inform the scope of the invention to those skilled in the art, it should be understood that they are exemplary in all respects and not limited. The invention is only defined by the scope of the claims.

1 and 2 is a configuration diagram showing a wire electric discharge machine according to the prior art.

Figure 3 is a block diagram showing a wire discharge processing machine of the AC power supply method according to the present invention.

Figure 4 is a graph showing the surface roughness measurement results processed through a wire electric discharge machine of the AC power supply method according to the present invention.

<Explanation of symbols for the main parts of the drawings>

300: amplification circuit 310: resonant circuit

320: switching circuit 330: power supply

340: processing object 350: wire

341, 351: discharge electrode

Claims (3)

In the wire electric discharge machine, A power supply unit 330 for supplying direct current (DC) power; A switching unit 320 connected to the power supply unit 330 and switching to generate resonance at a predetermined resonance frequency in the resonance circuit 310; A resonant circuit 310 connected to the switching unit 320 and configured of a series-parallel circuit using inductance and capacitance, and outputting a minimum discharge current at the predetermined resonant frequency; It is connected to the resonant circuit 310, and includes an amplifier circuit 300 for amplifying the size of the power supply by a predetermined size, Discharge electrodes 341 and 351 by converting direct current (DC) power supplied from the power supply unit 330 into alternating current (AC) power using the switching circuit 320, the resonance circuit 310, and the amplification circuit 300. AC power supply type wire discharge processing machine, characterized in that the supply to the liver. The method of claim 1, wherein the switching unit 320, AC power supply type wire discharge processing machine, characterized in that for generating the resonant frequency used in the resonant circuit 310 by switching. The method of claim 1, wherein the power supply unit 330, An AC power supply type wire discharge processing machine, characterized in that configured to be a variable power source to be applied voltage according to the type and thickness of the object to be processed (340).

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