JPH08300148A - Arc working equipment - Google Patents

Abstract

PURPOSE: To dispense with a high frequency generating equipment by connecting a capacitor between positive and negative output terminals, and intermittently flowing the DC current to a rector when the arc is started by a switching circuit. CONSTITUTION: A starting switch 8 is pressed to start an inverter circuit TR1, and the connection/disconnection command signal is fed to a switching circuit TR2. When the switching circuit TR2 is connected, the current flowing in the series circuits of a rector L1 and the switching circuit TR2 is increased. When the switching circuit TR2 is disconnected, the negative pulse-shaped high voltage is generated at the negative terminal of the reactor L1. The pulse-shaped high voltage charges a capacitor C4. The charged voltage of the capacitor C4 is boosted by repeating the connection and disconnection of the switching circuit TR2. When the charged voltage of the capacitor C4 is boosted higher than the breakdown voltage between an electrode 4 and a work 5, the spark discharge is generated to induce the main arc discharge for welding.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of an arc processing apparatus used for arc welding or cutting.

[0002]

2. Description of the Related Art FIG. 1 is a diagram showing an example of a conventional device in the case of arc welding when a high DC voltage is used for starting an arc. In FIG. 1, 10 is a welding power source, 1 to 3 are primary input lines, and 4 are electrodes which are held by a welding torch (not shown). Reference numeral 5 is a work piece, that is, a work piece, 6 is an electrode side cable, 7 is a work side cable, 8 is a start switch, and 9 is a remote output regulator. In the welding power source 10, DR1 is a primary rectifier circuit, C1 is a smoothing capacitor, T
R1 is an inverter circuit, T1 is an inverter transformer, D
R2 is a secondary rectifier circuit, L1 is a reactor, CT1 is an output current detector, CL1 is a control circuit, TR2 is a switching circuit, DR3 is a reverse blocking diode, Tm1 is an electrode side output terminal, and Tm2 is a workpiece side output terminal. is there.

In FIG. 1, when the start switch 8 is pressed,
The control circuit CL1 drives a gas supply circuit (not shown) by the input of this activation signal. Gas supply circuit is electrode 4
A shield gas is discharged between the workpiece and the workpiece 5. Control circuit CL, considering the time when the shield gas reaches the electrode 4
1 is an inverter circuit TR1 and a switching circuit T
Drive R2. The inverter circuit TR1 is several tens of kHz
Switching operation at the frequency of
The voltage necessary for the welding arc is induced on the secondary side of 1 and rectified by the secondary rectifying circuit DR2, and appears at the electrode side output terminal Tm1 and the workpiece side output terminal Tm2 via the reactor L1 and the reverse blocking diode DR3, It is applied between the electrode 4 and the workpiece 5. Switching circuit TR2 is reactor L1
And the positive output terminal of the secondary rectifier circuit DR2 conduct and cut off. When the switching circuit TR2 is going to be cut off from the conducting state, the current of the reactor L1 is going to suddenly change toward zero.
That is, a positive pulsed high voltage is generated at the secondary rectifying circuit DR2 side terminal of the reactor L1 and a negative pulsed high voltage is generated at the reverse blocking diode DR3 side terminal. This pulsed high voltage passes through the secondary rectifier circuit DR2, the workpiece side output terminal Tm2 and the workpiece side cable 7 on the positive side, and the reverse blocking diode D on the negative side.
It is applied between the electrode 4 and the workpiece 5 via R3, the electrode side output terminal Tm1 and the electrode side cable 6.

Here, when the pulsed high voltage is higher than the dielectric breakdown voltage between the electrode 4 and the workpiece 5, spark discharge is generated during this period, and the spark discharge causes the main arc for welding. A discharge is triggered. On the other hand, when the pulse voltage at this time is insufficient to break the insulation between the electrode 4 and the workpiece 5, this pulse voltage is applied to the electrode side cable 6 and the workpiece side cable 7. Charge stray capacitance between and. This charge is blocked by the reverse blocking diode DR3 and prevented from flowing back to the secondary rectifier circuit DR2, and is maintained. When the main arc does not occur due to the interruption of the previous switching circuit, the control circuit CL1 conducts the switching circuit TR2 again for a certain period of time after a certain period of time and again interrupts it. The reactor L1 again generates a pulsed high voltage due to the conduction and interruption of the switching circuit again. Since this high voltage has the same polarity as the voltage charged in the stray capacitance between the electrode side cable 6 and the workpiece side cable 7, the voltage is further increased. Even if the insulation between the electrode 4 and the workpiece 5 is not destroyed by this result, the switching circuit TR2 repeats conduction and interruption again. As a result, the charging of the stray capacitance between the electrode side cable 6 and the workpiece side cable 7 progresses, and eventually the insulation between the electrode 4 and the workpiece 5 is destroyed, and spark discharge occurs. However, this will trigger the main arc.

[0005]

In the above-mentioned conventional device, the reverse blocking diode DR3 blocks the charging charge charged in the floating capacitance between the electrode side cable 6 and the workpiece side cable 7 The backflow to the next rectifier circuit DR2 is prevented, but the electrostatic capacitance at the junction of the reverse blocking diode DR3 is prevented before the reverse blocking action is started.
It is necessary to charge by the electric charge of the floating capacitance between the workpiece side cable 7 and the workpiece side cable 7. However, since the welding current is generally large, the capacitance of the junction of the reverse blocking diode DR3 is not negligible with respect to the stray capacitance between the electrode side cable 6 and the workpiece side cable 7, and the reverse blocking diode DR3.
In some cases, the electrostatic capacitance of the joint portion becomes larger than the stray capacitance between the electrode side cable 6 and the workpiece side cable 7. Similarly, the secondary rectifier circuit DR2 also has a capacitance at the junction. For example, while the capacitance of each of the junctions of the secondary rectifier circuit DR2 and the reverse blocking diode DR3 is 5,000 to 20,000 pF,
The stray capacitance of the cable is at most 100 to 250 pF
It is a degree.

Therefore, when the pulse voltage of the reactor L1 generated when the switching circuit TR2 is cut off disappears, the charge charged in the electrostatic capacitance between the electrode side cable 6 and the workpiece side cable 7 through the reactor L1. Is supplied to the series circuit of the electrostatic capacitance of each junction of the secondary rectifier circuit DR2 and the reverse blocking diode DR3 to charge them. Here, the capacitance of the secondary rectifier circuit DR2 is C
2, the capacitance of the reverse blocking diode DR3 is C3, and the stray capacitance between the cables is Cs, the voltage Vcs charged in the stray capacitance between the cables by the voltage generated by the switching circuit TR2 and the reactor L1.
Becomes a voltage Vs that finally satisfies the following expression because the electrostatic capacity of each junction is charged when the pulsed voltage disappears. Cs.multidot.Vcs = (Cj + Cs) .Vs However, since Cj = C2.multidot.C3 / (C2 + C3), Vs = {Cs / (Cj + Cs)}. Multidot.Vcs. As mentioned above, C2 and C3 are Cs 2
If it is about 5 to 100 times, Cj will also be C2 and C
Since it is about 25 to 100 times that of 3, Vs = (1/26) Vcs to (1/101) Vcs, and Vs is significantly reduced from the initial voltage Vcs. Moreover, the electric charge charged at these junctions is discharged when the switching circuit TR2 is turned on next time. Therefore, in order to break the insulation between the electrode 4 and the workpiece 5, the switching circuit TR2 requires a very large number of conduction / interruption operations or the electrode 4 workpiece 5
It also means that the voltage to break the insulation between the two is not reached. Further, the repeated operation of the switching circuit TR2 diminishes the noise reduction effect of this system. This tendency becomes more remarkable as the cable becomes shorter, and changes greatly depending on the size of the stray capacitance between the cables.

[0007]

In order to solve the problems of the above-mentioned conventional device, the present invention comprises a capacitor having a capacitance sufficiently larger than the electrostatic capacitance of the junction of the reverse blocking diode DR3, and charges the capacitor once. It is intended to obtain a stable DC high voltage by accumulating the terminal voltage between the electrode 4 and the workpiece 5 to obtain a stable arc start with low noise.

[0008]

The present invention will be described below with reference to the illustrated embodiments. FIG. 2 is a connection diagram showing an embodiment of the present invention. In FIG. 2, the switching circuit TR2 includes reactors L1 and 2
It is a switching circuit for short-circuiting between the positive output terminal of the next rectifier circuit DR2 and forcibly flowing a current of the same polarity as the welding current in the reactor L1, such as a switching transistor or a gate turn-off thyristor (GTO). A self-extinguishing type switching element, a thyristor provided with a suitable commutation circuit, or a high voltage mechanical switch such as a vacuum switch can be used. C4 is a capacitor, DR
4 is a bypass diode and R4 is a resistor. CL2
Is a control circuit and controls the switching circuit TR2 together with the inverter circuit TR1. In the figure, the other parts and assemblies having the same functions as those of the conventional device of FIG.

In FIG. 2, at the start of welding, an operator brings the electrode 4 close to the workpiece 5 and presses the start switch 8. The control circuit CL2 receives the activation signal from the activation switch 8 and sends a drive signal to the inverter circuit TR1 to activate it, and at the same time supplies a conduction / interruption command signal to the switching circuit TR2. The startup of the inverter circuit TR1 causes several tens of kHz on the primary side of the inverter transformer T1
Is converted into a voltage value required for arc welding on the secondary side, converted into a direct current by the secondary rectifier circuit DR2, and applied to the series connection circuit of the reactor L1 and the switching circuit TR2. When the switching circuit TR2 becomes conductive, the output of the secondary rectification circuit DR2 is short-circuited through the reactor L1, and the current flowing through the series circuit of the reactor L1 and the switching circuit TR2 increases with the passage of time. The control circuit CL2 is a reactor L
1 and the switching circuit TR2, when the current flowing through the series circuit reaches a certain value, the drive signal to the inverter circuit TR1 is kept applied and the switching circuit T1 is applied.
The conduction command signal for R2 is cut off and cut off. As a result, the current of the reactor L1 tends to suddenly change toward zero, so that the sudden change is prevented, that is, the secondary rectifier circuit DR2 side terminal of the reactor L1 is positive, and the reverse blocking diode DR3 side terminal is negative pulse-shaped. High voltage is generated.
This pulsed high voltage is applied to the reactor L1, the secondary rectifier circuit DR2, the capacitor C4, the bypass diode DR.
4. The capacitor C4 is charged by the circuit of the reverse blocking diode DR3.

At this time, the capacity of the capacitor C4 is sufficiently larger than the capacity of the junction of the secondary rectifier circuit DR2 and the reverse blocking diode DR3, and is, for example, about 10 times (reverse to that of the secondary rectifier circuit DR2 as shown above. If the electrostatic capacitances of both junctions of the blocking diode DR3 are about 10,000 pF in total, then approximately 0.001 μF), and most of the energy stored in the reactor L1 is charged in the capacitor C4. It will be. The voltage charged in the capacitor C4 and the stray capacitance Cs between the cables by the pulsed voltage is Vcs, and when the pulsed voltage disappears, the electrostatic capacitance Cj of both the junctions of the secondary rectifier circuit DR2 and the reverse blocking diode DR3. = C2.C3 / (C2 + C3) where Vs is the voltage charged and C4 is the capacitance of the capacitor C4, (C4 + Cs) Vcs = (C4 + Cs + Cj) Vs, so Cs << C4 , Cj = C4 .1 / 1
When set to 0, Vs = Vcs · 10/11 and almost no change. The charging voltage of the capacitor C4 rises as the switching circuit TR2 repeats conduction and interruption, and the positive side has a workpiece side output terminal T.
It is applied between the electrode 4 and the workpiece 5 via m2 and the workpiece side cable 7, and on the negative side via the current limiting resistor R4, the electrode side output terminal Tm1 and the electrode side cable 6. When this high voltage is higher than the dielectric breakdown voltage between the electrode 4 and the workpiece 5, spark discharge is generated during this period, and this spark discharge induces the main arc discharge for welding. The conduction / interruption operation of the switching circuit TR2 may be stopped when the occurrence of the main arc is detected by the current detector CT1, or when the voltage of the capacitor C4 reaches a constant value or the voltage of the capacitor C4. May be stopped after repeating conduction and interruption a certain number of times in anticipation of reaching a certain value. In addition, the reverse blocking diode DR
Numeral 3 prevents the secondary rectifier circuit DR2 from being damaged by the high voltage applied between the electrode side output terminal Tm1 and the workpiece side output terminal Tm2 being applied to the secondary rectifier circuit DR2.

As described above, most of the electromagnetic energy held by the reactor L1 is charged in the capacitor C4, and this charged electric charge is applied between the electrode 4 and the workpiece 5 through the current limiting resistor R4. Side cable 6
The stray capacitance between the workpiece and the work-side cable 7 is charged to almost the terminal voltage of the capacitor C4, and the voltage between the electrode 4 and the work 5 rapidly rises to a level between these. The main arc is triggered when the insulation of is broken. The generation of the main arc is detected by the output current detector CT1, and the control circuit CL1 stops the repeated operation of the conduction interruption of the switching circuit TR2 and keeps the interruption state. As a result, the number of times of charging / discharging the stray capacitance is reduced, and the generation of noise accompanying this is also reduced.

FIG. 3 shows another embodiment. In the figure, the bypass diode DR4 is connected between the reactor L1 and the reverse blocking diode DR3, and the capacitor C4 is connected.
2 is different from the embodiment of FIG. 2 only in that the charging circuit of FIG. 2 does not include the reverse blocking diode DR3, and the other points are the same as those of FIG.

2 and 3, the reverse blocking diode DR3 may be connected between the positive side terminal of the secondary rectifier circuit DR2 and the output terminal Tm2 so that the output terminal Tm2 side serves as a cathode. Also, the resistor R4 and the diode DR
4 is omitted and the capacitor C4 is directly connected to the output terminals Tm1 and Tm2.
You may connect between and. Further, in any of the above-mentioned embodiments, if a resistor of several 100 MΩ is connected in parallel with the capacitor C4, the high voltage charged in the capacitor C4 will not be generated even if the arc starting fails. After the operation is stopped, it discharges and drops in a relatively short time, so that there is no danger of electric shock even if the electrode is touched by mistake.

FIG. 4 is a modification of FIGS. 2 and 3 as described above, and includes diode DR4 and resistor R4.
Is excluded. A resistor R5 is connected between the output terminals. As a result, the residual electric charge of the capacitor C4 is discharged in a relatively short time after the operation is stopped. It is desirable that the resistance value of this resistor is set to, for example, about several seconds so that the discharge time constant becomes sufficiently smaller than the repeating cycle of conduction / interruption of the switching circuit TR2 according to the capacitance of the capacitor C4.

FIG. 5 shows still another embodiment. In the figure, the series circuit of the capacitor C4 and the resistor R4 is connected in parallel to the series circuit of the reactor L1 and the reverse blocking diode DR3, and occurs in the reactor L1 when the switching circuit TR2 is cut off from conduction. The pulsed high voltage charges the capacitor C4 with the circuit of the reactor L1, the capacitor C4, and the bypass diode DR4. The high voltage charged in the capacitor C4 is the secondary rectifier circuit DR2, the workpiece side output terminal Tm2, the workpiece side cable 7 on the positive side, the current limiting resistor R4, the electrode side output terminal Tm1 on the negative side, The electrode-side cable 6 is passed between the workpiece 5 and the electrode 4 via the electrode-side cable 6. At this time, the bypass diode DR4 prevents the high voltage of the capacitor C4 from being short-circuited by the reactor L1, and the reverse blocking diode DR3 causes the capacitor C4 to short.
4 is prevented from being short-circuited by the reactor L1 due to the high voltage appearing at both ends of the series circuit of the current limiting resistor R4 and the current limiting resistor R4, and the stray capacitance between the electrode side cable 6 and the workpiece side cable 7 is charged. Secondary rectification circuit DR by charge
The reverse high voltage is prevented from being applied to 2. Others are the same as those in FIG. 2, and thus detailed description of the operation is omitted.

FIG. 6 shows another embodiment. In the figure, only the point that the bypass diode DR4 and the resistor R4 are in parallel is different from the embodiment of FIG. In the case of the same drawing, the pulsed high voltage generated in the reactor L1 is the reactor L1, the capacitor C4, the bypass diode D.
R4, reverse blocking diode DR3 circuit C4
To charge. The high voltage charged in the capacitor C4 is the secondary rectifier circuit DR2, the workpiece side output terminal Tm2, the workpiece side cable 7 on the positive side, the current limiting resistor R4, the electrode side output terminal Tm1 on the negative side, The electrode-side cable 6 is passed between the workpiece 5 and the electrode 4 via the electrode-side cable 6. At this time, the reverse blocking diode D
R3 prevents the high voltage appearing across the series circuit of the capacitor C4 and the current limiting resistor R4 from being short-circuited by the reactor L1. Since the others are the same as those in FIG. 5, detailed description of the operation is omitted.

FIG. 7 shows still another embodiment, in which a reactor L2 is provided as a reactor for generating a high voltage due to arc firing. In the figure, the reactor L
2 is divided into two insulated windings L2 (1/2) and L2 (2/2), and both windings are magnetically tightly coupled. The switching circuit TR2 interrupts the current of the reactor L2 (1/2), and the capacitor C4 is charged by the pulsed high voltage induced in the magnetically coupled reactor L2 (2/2). Others are the same as those in FIG. 5, and thus detailed description will be omitted.

FIG. 8 shows still another embodiment. Reactor L2 has two insulated windings L2 (1/2) and L2 (2 /
2), the switching circuit TR2 interrupts the current of the reactor L2 (1/2), and the reactor L2 (2/2)
The capacitor C4 is charged by the pulse-like high voltage generated at. Others are the same as those in FIG. 6, so detailed description will be omitted.

In the embodiment of FIGS. 7 and 8, the current flowing through the switching circuit TR2 can be freely set by appropriately selecting the turns ratio of the reactors L2 (1/2) and L2 (2/2). You can do it.

FIG. 9 shows still another embodiment. In the figure, an inverter transformer T2, which is insulated from the welding output circuit, is used as a power source for the current flowing in the reactor L2 (1/2).
7 is different from FIG. 7 in that a secondary winding and a secondary rectifying circuit DR5 thereof different from those on the welding output circuit side are separately provided, and other details are the same as in FIG. In the embodiment shown in the figure, the switching circuit TR2
Is insulated from the welding circuit, the control circuit is easily insulated from the welding circuit.

FIG. 10 shows still another embodiment. In the figure, the reactor L3 is two insulated windings L3.
It is divided into (1/2) and L3 (2/2), and the current of reactor L3 (1/2) is interrupted by TR2, and the high voltage pulsed to reactor L3 (2/2) causes reactor L3 (2). /
2) The capacitor C4 is charged by the circuit of the capacitor C4 and the bypass diode DR4. The high voltage charged in the capacitor C4 is L1 on the positive side, the secondary rectification circuit DR2, the workpiece side output terminal Tm2, the workpiece side cable 7, the negative side is the bypass diode R4, the electrode side output terminal Tm1, The electrode side cable 6 is passed between the workpiece 5 and the electrode 4 via the electrode side cable 6.
At this time, the reverse blocking diode DR3 prevents the high voltage appearing at both ends of the series circuit of the capacitor C4 and the current limiting resistor R4 from being short-circuited by the welding current circuit, and the bypass diode DR4 acts as a reactor L3 (2/2). Prevents the high voltage of the capacitor C4 from being short-circuited. In the case of the same figure, no welding current flows through the reactor L3 (2/2). Therefore, the current capacity may be smaller than that of the reactor L2 (2/2) of the embodiment shown in FIGS. Others are the same as those in FIG. 9, so detailed description will be omitted.

FIG. 11 shows another embodiment. In the figure, the reactor L4 is composed of a main winding L4 (1/2) and an auxiliary winding L4 (2/2) magnetically coupled to the main winding L4 (1/2), and the switching circuit TR2 is a secondary winding through the reactor L4 (1/2). The output of the rectifier circuit DR2 is connected so as to be short-circuited. The reactor auxiliary winding L4 (2/2) is connected between the terminals of the capacitor C4 in series with the bypass diode DR4. In the figure, the switching circuit TR2 interrupts the current of the reactor L4 (1/2), and the high voltage pulse generated in the reactor L4 (2/2) causes the reactor L4 (2/2), the capacitor C4, and the bypass diode. The capacitor C4 is charged by the circuit of DR4. The high voltage charged in the capacitor C4 includes the work side output terminal Tm2 and the work side cable 7 on the positive side, the current limiting resistor R4, the electrode side output terminal Tm1, and the electrode side cable 6 on the negative side. After that, it is applied between the workpiece 5 and the electrode 4. At this time, the reverse blocking diode DR3 prevents the high voltage of the capacitor C4 from being applied to the secondary rectification circuit DR2 and destroying the secondary rectification circuit DR2, and the bypass diode DR4 acts as the reactor L4.
(2/2) prevents the high voltage charged in the capacitor C4 from being short-circuited. In the case of the figure, the reactor L4 (1 /
No welding current flows in 2). Therefore, the reactor L4 is the reactor L2 of the embodiment shown in FIGS.
A current capacity smaller than (2/2) will suffice.
Others are the same as those in FIGS. 2 to 4, and thus detailed description will be omitted.

FIG. 12 shows still another embodiment. In the case of the same drawing, as in the embodiment of FIG. 10, the reactor L divided into two insulated windings L5 (1/2) and L5 (2/2).
5 is used, and the reactor L5 (2/2) is connected to both ends of the capacitor C4 in series with the bypass diode DR4. The switching circuit TR2 interrupts the current of the reactor L5 (1/2), and the high voltage pulse generated in the reactor L5 (2/2) causes the reactor L5 (2 /) to flow.
2) The capacitor C4 is charged by the circuit of the capacitor C4 and the bypass diode DR4. The high voltage charged in the capacitor C4 includes the work side output terminal Tm2 and the work side cable 7 on the positive side, the current limiting resistor R4, the electrode side output terminal Tm1, and the electrode side cable 6 on the negative side. Work piece 5
And between the electrode 4. At this time, the reverse blocking diode DR
3 prevents the high voltage of the capacitor C4 from being applied to the secondary rectifier circuit DR2 and destroying the secondary rectifier circuit DR2, and the bypass diode DR4 short-circuits the high voltage charged in the capacitor C4 by the reactor L5 (2/2). To be prevented. Also in the case of the same drawing, since the welding current does not flow in the reactor L5 (2/2) like the reactor L3 (2/2) of the embodiment shown in FIG. 10, a small current capacity is sufficient. Others are the same as those in FIG. 2 to FIG. 4 and FIG. 11, so detailed description will be omitted.

[0024]

[Other Embodiments] In FIGS. 2 to 6, a switching circuit TR2 is provided in an intermediate terminal of a reactor L1 and is connected between the intermediate terminal and a positive output terminal of a secondary rectifying circuit DR2 to form a direct current in a part of the reactor L1. You may make it pass an electric current and make it intermittent.

In FIGS. 7 to 9, the reactor L is shown.
If 2 (2/2) also has the function of the reactor L1, the reactor L1 can be omitted.

Also in the embodiment of FIGS. 5 to 12, the diode DR4 and the resistor R4 may be omitted. In this case, in FIGS. 5 to 9, the diode DR4 and the resistor R4 may be removed, and the capacitor C4 may be connected between the output terminal Tm1 and the negative output terminal of the secondary rectifier circuit DR2. 10 to 12, the resistor R4 may be removed and the diode DR4 and the capacitor C4 may be directly connected to the output terminal Tm1.

Furthermore, when the starting operation is performed, the electrode 4 is brought close to the object to be welded 5, and the arc is started when the conduction and interruption of the switching circuit TR2 are repeated several times. Switching circuits usually stop operating. However, if the electrode is too far from the work piece, it will not start forever. In such a case, the repetition of the conduction cutoff operation of the switching circuit TR2 is useless and the high voltage is continuously applied to the electrodes. Therefore, in order to prevent this and protect the equipment, the switching circuit is turned on. It is desirable to limit the number of times the -OFF operation is stopped so that it will stop after several to ten or more times. To do this,
The control circuit CL2 may be provided with a function of counting the number of times the switching circuit TR2 operates and stopping the device as an abnormality when the number of repetitions reaches a set number.

In each of the above embodiments, the main circuit of the welding power source has been described using the inverter control type, but in implementing the present invention, the main circuit system of the welding power source is not limited to the inverter control type. That is, thyristor control or DC chopper control on the secondary side of the transformer may be used. Further, it is needless to say that the output form thereof may be a component including a periodically pulsating component or a pulse waveform other than the direct current described above.

Further, although the above-mentioned embodiments have been described only with respect to the case where the present invention is applied to arc welding, the present invention can be applied to any processing which uses arc discharge, for example, Arc cutting in addition to welding
It can be applied to arc spraying, arc heating, arc melting, etc.

It can also be applied to plasma arc welding and plasma arc cutting without using a pilot arc.

[0031]

As described above, the present invention does not use the high frequency generated by the high frequency generator and repeats conduction and interruption of the current flowing in the reactor, and the high voltage generated at the time of interruption is temporarily charged in the capacitor to cause pulsation. Since it is used to start an arc with a high DC voltage with a small amount of electricity, a large and expensive high-frequency generator is not required, and regardless of the length of the cable or the size of the stray capacitance between the electrode and the work piece. It is possible to reliably start the arc and almost eliminate noise interference.

[Brief description of drawings]

FIG. 1 is a connection diagram showing an example of a conventional arc processing device.

FIG. 2 is a connection diagram showing an embodiment when the present invention is applied to arc welding.

FIG. 3 is a connection diagram showing another embodiment when the present invention is applied to arc welding.

FIG. 4 is a connection diagram showing another embodiment when the present invention is applied to arc welding.

FIG. 5 is a connection diagram showing still another embodiment when the present invention is applied to arc welding.

FIG. 6 is a connection diagram showing still another embodiment when the present invention is applied to arc welding.

FIG. 9 is a connection diagram showing still another embodiment when the present invention is applied to arc welding.

FIG. 10 is a connection diagram showing still another embodiment when the present invention is applied to arc welding.

FIG. 11 is a connection diagram showing still another embodiment when the present invention is applied to arc welding.

FIG. 12 is a connection diagram showing still another embodiment when the present invention is applied to arc welding.

[Explanation of symbols]

 4 Electrode 5 Workpiece 6 Electrode side cable 7 Workpiece side cable 8 Start switch 9 Remote output regulator 10 Welding power supply 11 Welding power supply DR1 Primary rectification circuit DR2 Secondary rectification circuit DR3 Reverse blocking diode DR4 Bypass diode DR5 Secondary Rectifier circuit TR1 Inverter circuit TR2 Switching circuit T1, T2 Inverter transformer L1 Reactor C4 Capacitor L2 (1/2), L2 (2/2) Reactor L3 (1/2), L2 (2/2) Reactor L4 (1/2) ), L4 (2/2) Reactor L5 (1/2), L5 (2/2) Reactor CT1 Output current detector CL1, CL2 Control circuit Tm1 Electrode side output terminal Tm2 Workpiece side output terminal R1 Resistor R4 current Limiting resistor R5 Discharge resistor

Front page continuation (72) Inventor Hitoshi Nakamura 2-11-1, Tagawa, Yodogawa-ku, Osaka DAIHEN CORPORATION

Claims (13)

[Claims] 1. A series circuit of a reactor and a reverse blocking diode is connected in series between a DC power source and an output terminal, a capacitor is connected between the positive and negative output terminals, and the reactor or a part of the reactor is connected at the time of starting an arc. An arc machining device with a switching circuit for forcibly flowing a DC current repeatedly and intermittently at a predetermined time width and interval. 2. A series circuit of a reactor and a reverse blocking diode is connected in series between a DC power source and an output terminal, and a series circuit of a capacitor and a resistor is connected between positive and negative output terminals,
A switching circuit is provided for forcibly and repeatedly flowing a direct current in the reactor or a part of the reactor at a predetermined time width and an interval at the time of starting an arc, and the switching circuit is for the voltage generated in the reactor at the time of interruption. Arc processing device in which a diode is connected to a position that bypasses the resistor with a forward polarity. 3. A series circuit of a reactor and a reverse blocking diode is connected in series between a DC power supply and an output terminal, and a capacitor is connected in parallel to the reactor or the series circuit of the reactor and a reverse blocking diode, An arc machining device provided with a switching circuit for forcibly and intermittently flowing a DC current in a predetermined time width and interval in the reactor or a part of the reactor when the arc is started. 4. A series circuit of a reactor and a reverse blocking diode is connected in series between a DC power supply and an output terminal, and a series circuit of a capacitor and a resistor is connected in series with the reactor or the reactor and the reverse blocking diode. Connected in parallel to the circuit, provided a switching circuit for forcibly and intermittently flowing a direct current to the reactor or a part of the reactor at a predetermined time width and interval at the time of arc start, and when the switching circuit is cut off, An arc machining device in which a diode is connected to a position that bypasses the resistor with a polarity that becomes a forward direction with respect to a voltage generated in a reactor. 5. The reactor has an auxiliary winding that is magnetically coupled, and the switching circuit replaces the reactor when the arc is started and forcibly applies a direct current to the auxiliary winding at predetermined time widths and intervals to intermittently repeat. 5. The arc machining apparatus according to claim 1, wherein the arc machining apparatus is a circuit that flows through the circuit. 6. An auxiliary reactor having a primary and a secondary winding, wherein a series circuit of a reactor and a reverse blocking diode is connected in series between a DC power source and an output terminal, a capacitor is connected between the positive and negative output terminals. And a switching circuit for forcibly and intermittently flowing a direct current at a predetermined time width and interval in the primary winding of the auxiliary reactor when the arc is started, and the secondary winding of the auxiliary reactor is the switching circuit. Is connected in parallel with the capacitor in series with a diode having a polarity that is in the forward direction with respect to the voltage generated in the secondary winding of the auxiliary reactor at the time of interruption. 7. A series circuit of a reactor and a reverse blocking diode is connected in series between a DC power source and an output terminal, and a series circuit of a capacitor and a resistor is connected between positive and negative output terminals,
An auxiliary reactor having primary and secondary windings and a switching circuit for forcibly and intermittently flowing a DC current at a predetermined time width and interval at the time of starting an arc are provided in the primary winding of the auxiliary reactor. An arc processing device in which the secondary winding of the auxiliary reactor is connected in parallel to the capacitor in series with a diode having a polarity that is in a forward direction with respect to the voltage generated in the secondary winding of the auxiliary reactor when the switching circuit is cut off. . 8. A series circuit of a reactor and a reverse blocking diode is connected in series between a DC power supply and an output terminal, and a capacitor is connected in parallel to the reactor or the series circuit of the reactor and a reverse blocking diode, An auxiliary reactor having primary and secondary windings, and a switching circuit for forcibly and intermittently flowing a direct current to the primary winding of the auxiliary reactor at a predetermined time width and interval when the arc is started are provided. Arc machining in which the secondary winding of the auxiliary reactor is connected in parallel with the capacitor by making the secondary winding of the auxiliary reactor in series with a diode having a polarity that is forward to the voltage generated in the secondary winding of the auxiliary reactor when the switching circuit is cut off. apparatus. 9. A series circuit of a reactor and a reverse blocking diode is connected in series between a DC power source and an output terminal, and a series circuit of a capacitor and a resistor is connected in series with the reactor or the reactor and the reverse blocking diode. An auxiliary reactor connected in parallel with the circuit and having primary and secondary windings,
A switching circuit for forcibly and intermittently flowing a DC current in the primary winding of the auxiliary reactor at a predetermined time width and interval at the time of starting the arc is provided, and the secondary winding of the auxiliary reactor is provided with the switching circuit. An arc machining device in which a diode having a polarity that is in a forward direction with respect to a voltage generated in the secondary winding of the auxiliary reactor at the time of interruption is connected in series with the capacitor in series. 10. A capacitor, a series circuit of the capacitor and a resistor, or between the output terminals,
10. The arc machining apparatus according to claim 1, wherein high resistance resistors forming a discharge circuit of the capacitor are connected in parallel. 11. The arc machining apparatus according to claim 1, wherein the switching circuit includes a DC power source insulated from a welding circuit and a switching element. 12. The arc machining apparatus according to claim 1, wherein the switching circuit is a circuit that stops operation when a main arc for machining occurs. 13. The switching circuit according to claim 1, wherein the switching circuit is a circuit that stops when a main arc for machining occurs or when the operation is repeated a predetermined number of times, whichever comes first. Arc processing device described in the crab.