JP3425374B2 - Engine driven arc welding machine - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine-driven arc welding machine, and more particularly to an arc welding machine in which the characteristics can be selected according to the type and welding position of a coated welding rod.

[0002]

2. Description of the Related Art In an engine-driven arc welding machine, an output obtained by driving a welding generator by an engine is controlled by a control element according to a control signal, and one of the welding output terminals has a welding rod. Is used as an electrode and the other base metal is used as an electrode to generate an arc between both electrodes and perform welding.

In arc welding, a short circuit frequently occurs due to the molten metal or the welding rod coming into contact with the base metal. At this time, if the output characteristic of the welding machine is such that a large current flows at the time of re-arcing, molten metal can be scattered, so that re-arcing easily occurs although spatter and the like increase. On the other hand, in the case where a large current is not passed during re-arcing in order to improve the welding quality, re-arcing is less likely to occur and the arc is broken, or the welding rod easily sticks to the base metal. Depending on the skill of the worker, the welding work may be interrupted. This tends to occur especially when working in a small current region or short arc.

[0004]

In the conventional welding machine which applies a large current at the time of short circuit, the characteristic transition voltage of the characteristic change from the constant current characteristic to the current increase and the increased constant current characteristic value as the short circuit current are The arc characteristics are preset to match the welding rods commonly used in Japan.Therefore, depending on the type and welding position of the welding rod, arc breakage, sticking of the welding rod and the base metal, and frequent occurrence of spatter are allowed. I have to do it. In addition, when a high-level technician performs welding, if spatter increases, there is a problem that the aesthetics of the welding bead is deteriorated and workability is deteriorated, and a fine adjustment of the rod is not possible. And, when welding is performed with a high-cellulosic coated welding rod which is widely used especially in foreign countries, it may not be applicable to this.

The present invention has been made in consideration of the above points, and an engine for supplying power by appropriately adjusting the arc current and short circuit current at the time of droplet transfer required depending on the type of the coated welding rod and the welding posture. An object is to provide a drive type arc welder.

[0006]

To achieve the above object, in the present invention, an engine-driven welding generator according to claim 1 and an output of the welding generator according to a control signal are controlled. An output circuit for supplying to the welding output terminal, a current detector for detecting a current flowing through the welding output terminal, and an error detector for detecting an error by comparing the output of the current detector with a reference signal, A control signal forming circuit that forms the control signal according to the output of the error detector and supplies the control signal to the output circuit, and a voltage detector that detects the voltage supplied to the welding output terminal are provided. In an engine-driven arc welder that has current-controlled arc characteristics, exhibits drooping characteristics near the arc voltage, and has constant current characteristics that increases the current when the arc voltage decreases, depending on the output of the voltage detector. An adjusting circuit for determining the magnitude of a reference signal to be applied to the error detector, the reference circuit comprising:
Corresponding to the arc current by changing the signal
Transition point between constant current control arc characteristics and the drooping characteristics
It is equipped with an adjustment circuit that makes the voltage of
By changing the constant value corresponding to the arc current.
Of the transition point between the characteristics of the current control arc characteristics and the drooping characteristics
An engine-driven arc welder having a variable voltage , and an engine-driven welding generator according to claim 2, and controlling the output of the welding generator according to a control signal. An output circuit for supplying the output terminal for welding, a current detector for detecting a current flowing through the output terminal for welding, an error detector for detecting an error by comparing the output of the current detector with a reference signal, and A control signal forming circuit that forms the control signal according to the output of the error detector and applies the output signal to the output circuit, and a voltage detector that detects the voltage applied to the welding output terminal, and a constant current based on the reference signal. The output of the voltage detector in an engine-driven arc welder that has controlled arc characteristics, exhibits drooping characteristics near the arc voltage, and has constant current characteristics in which the current increases when the arc voltage decreases. A regulating circuit for determining the magnitude of the reference signal to be supplied to the error detector in accordance with the group
By changing the quasi-signal, the drooping characteristic and the short circuit current
Corresponding to the constant current control arc characteristic transition point between characteristics
It has an adjusting circuit that makes the current of the
By changing the drooping characteristic and the short-circuit current.
The voltage at the transition point between the characteristics of the constant current control arc and the characteristics of
Provided is an engine-driven arc welder, which has a variable flow .

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the configuration of an embodiment of the present invention. This Figure 1 shows
Shows the main circuit, that is, the welding current output circuit, and on the left side,
The control circuit is shown.

In the main circuit, the output of the welding generator G is rectified by the mixing bridge circuit by the thyristors SCR1-SCR3 and the diodes D1-D3, and is not shown from the welding output terminals P and N via the reactor L. Electric power is supplied between the welding rod and the base material to generate an arc for welding.

The control circuit is surrounded by a two-dot chain line.
2 shows the thyristor drive circuit connected to the gate of the thyristor SCR in the main circuit and this thyristor drive circuit
Error that is given around the part surrounded by the dotted line and that gives the error signal detected according to the voltage detection signal and the current detection signal in the main circuit to the thyristor drive circuit as a reference signal to be compared with each phase voltage signal And a detection circuit.

The error detection circuit has an error amplifier EA, the welding current detected by the DC current transformer CT is given as a voltage signal to its + input terminal, and the variable resistors VR1 and VR2 are supplied to its − input terminal. , A reference voltage forming circuit including a variable three-terminal regulator REG1 and a grounding resistor R3, and each voltage from the reference voltage adjusting circuit that is connected to the reference voltage forming circuit via a diode D10 and adjusts the reference voltage. A signal is given. The negative terminal of the error amplifier EA is feedback-connected to the output terminal by the resistor R1.

The reference voltage forming circuit is composed of a variable 3-terminal regulator REG1, a variable resistor VR for adjusting the arc current, a variable resistor VR2 for adjusting the variation of each product, resistors R3 to R6 and an electrolytic capacitor C1. That is, the circuit power supply
In parallel with the resistors R5 and R6 in the series circuit of resistors R4, R5 and R6 connected between + 12V and ground, the variable capacitor 3-terminal regulator REG1 is connected across the anode and cathode and the electrolytic capacitor C1. The control terminal of the variable 3-terminal regulator REG1 is connected to the connection point of R5 and R6. The cathode of the variable 3-terminal regulator REG1 is grounded through the resistor R2, the variable resistors VR2, VR1 and the resistor R3, and the connection point between the variable resistor VR1 and the resistor R3 is connected to the-terminal of the error amplifier EA. There is.

As a result, the variable 3-terminal regulator REG1
The shared voltage of the resistor R6 in the series circuit of the resistors R4 to R6 is always applied to the control terminal of, and a constant voltage corresponding to this is generated between the anode and the cathode. This constant voltage is grounded via the resistor R2, the variable resistors VR2, VR1 and the resistor R3, and is applied as a reference signal to the negative terminal of the error amplifier EA from the connection point between the variable resistor VR1 and the resistor R3.

The variable three-terminal regulator REG1 generates a voltage between the anode and the cathode that is approximately proportional to the voltage applied to the control terminal, and can be used as a controllable constant voltage element.

On the other hand, the reference voltage adjusting circuit is composed of a resistor R10, a variable resistor VR10 as a voltage dividing circuit and a constant voltage element.
A voltage output is formed by the photocoupler PC-I which is fed by the voltage response of the variable 3-terminal regulator REG2 similar to the above-mentioned REG1, and is supplied to the-input terminal of the error amplifier EA via the diode D10. That is, the divided voltage taken out from the voltage dividing circuit by the resistor R10 and the variable resistor VR10 connected to the connection points P ′ and N ′ with the output line of the mixed bridge circuit is passed through the noise eliminating CR filter. Is applied to the control terminal of the variable 3-terminal regulator REG2, and when a voltage higher than a predetermined value is applied between the anode and the cathode of the variable 3-terminal regulator REG2, a current flows through the variable 3-terminal regulator REG2 and the photocoupler PC-I emits light. The diode is caused to emit light to make the phototransistor conductive. Here, the protection circuit for the high voltage of the variable 3-terminal regulator REG2 is omitted.

As a result, the variable resistor VR20 becomes the protective resistor R20.
The phototransistor of the photocoupler PC-1 connected in series via the photocoupler is also controlled in conduction degree according to the amount of light emitted from the light emitting diode in the photocoupler, and the phototransistor shares the voltage with the variable resistors VR20, R20 and R3. The applied voltage is applied to the-terminal of the error amplifier EA via the diode D10. The negative terminal of the error amplifier EA is
It is grounded by a noise removing capacitor.

Then, the current detection signal from the DC current transformer CT having a built-in operational amplifier (not shown) is applied to the + terminal of the error amplifier EA, and is compared with the reference signal applied to the-terminal. The error between the two obtained by this is connected to the other end of the resistor R11 whose one end is connected to the circuit power supply,
It is given from the output terminal of the error amplifier EA to the + terminal for inputting the reference signal of the comparator CP via the resistor R12.

A signal corresponding to the u-phase voltage of the welding generator G is given to the-terminal of the comparator CP for taking in the input signal to be compared with the reference signal. That is, this u-phase voltage is applied to the light emitting diode of the photocoupler PC-U, and the voltage signal formed by the phototransistor is applied to the negative terminal of the comparator CP according to the amount of emitted light, and the comparator CP outputs the corresponding output. Is given to the light emitting diode of the photocoupler PC-O via the resistor R13. Then, from the phototransistor of the photocoupler PC-O,
An energization control signal is given to the gate of thyristor SCR1 via R14. That is, the thyristor SCR1 is energized and controlled according to the outputs of the error detection circuit and the thyristor drive circuit according to the output voltage and output current of the mixed bridge circuit.

Although not shown in FIG. 1, a similar circuit configuration is adopted for the v-phase and the w-phase.

FIG. 2A is a diagram in which only the relevant portion is extracted in order to explain the operation of the error amplifier EA according to the output voltage detection signal of the mixing bridge in the circuit of FIG. That is, the connection point P ′ in the mixed bridge circuit
A welding voltage E (no-load voltage V1 or short-circuit voltage VS) given to the welding output terminals P 1 and N 2 is given to N and N '.

This welding voltage E is applied to the resistance R10 and the variable resistance VR10.
The voltage divided by the voltage division ratio with
It is given to the control terminal of REG2, and the voltage according to this is variable 3
It occurs between the anode and cathode of the terminal regulator REG2. As a result, the voltage of the connection point P'-N 'can be varied 3
The voltage obtained by subtracting the share of the terminal regulator REG2 is applied to both the light emitting diode of the photocoupler PC-I and the resistor R15 while the voltage is applied to both of them. And protective resistance
When electricity is supplied through R15, light corresponding to the voltage between the connection points P′-N ′ is generated from the light emitting diode and given to the phototransistor of the photocoupler PC-I.

In response to this, in the phototransistor of the photocoupler PC-I, a voltage obtained by dividing the voltage (+ 12V) of the circuit power supply by the phototransistor, the resistor R20 and the variable resistor VR20 is generated, and the generated voltage is generated. Is fed to the negative terminal of the error amplifier EA through the diode D10.

Here, the variable resistor VR20 is inserted in series between the resistor R20 and the phototransistor as shown in FIG. 2 (a), and as shown in FIG. 2 (b). There is a configuration in which the transistor is connected so as to straddle the emitter-collector of the transistor. FIG. 3A shows an equivalent circuit of the variable 3-terminal regulator shown in FIGS. 1 and 2A. As is clear from this equivalent circuit, in the range where the control signal voltage Vref applied to the control terminal (-) exceeds the constant voltage Vz applied to the reference signal terminal (+), the anode-cathode voltage becomes the control signal voltage Vref. It is a configuration that corresponds.

FIG. 3 (b) shows the measured control characteristic, and the anode-cathode voltage VA-K is approximately proportional to the control signal voltage Vref. In the characteristic diagram, the horizontal axis represents the control signal voltage Vref to be given to the control terminal, and the vertical axis represents the anode-cathode voltage VA-K.

As for the variable three-terminal regulator REG1, constant voltage characteristics are obtained by using a region in which the control signal voltage Vref in FIG.

Regarding the variable 3-terminal regulator REG2, the control signal voltage Vref to be applied to the control terminal is
The voltage between the connection points P'-N 'is divided by the voltage dividing ratio by the resistor R10 and the variable resistor VR10. Then, the voltage VA-K corresponding to the control signal voltage Vref is generated between the anode and the cathode of the variable three-terminal regulator REG2, and this voltage VA-K becomes the shared voltage of the variable three-terminal regulator REG2.

FIG. 3C shows the rising characteristic of the variable 3-terminal regulator from off to on (falling characteristic from on to off). That is, the variable three-terminal regulator becomes almost completely conductive when the anode-cathode voltage VA-K is about 2.5V and almost completely disconnected at about 1.0V. This is used for the output characteristics described later.

FIG. 4 shows the output voltage of the welding machine due to the change in resistance values of the variable resistor VR10 provided on the light emitting diode side of the photocoupler PC-I shown in FIG. 2 and the variable resistor VR20 provided on the phototransistor side. The change characteristics of the output current and the adjustment content thereof are shown.

The welding machine of the present invention has two constant current characteristics I and II.
It has an output characteristic that is a combination of I and drooping characteristic II. The constant current characteristics also include some drooping characteristics (the drooping characteristics include constant voltage characteristics).

The first constant current characteristic I is the − of the error amplifier EA.
It is obtained by keeping the terminal at a constant voltage set by the variable resistor VR1. This constant voltage is turned on when the phototransistor of the photocoupler PC-I is conducting, that is, when the arc voltage is high, that is, V1 or V2, and is grounded by the phototransistor, so the voltage is blocked by the diode D10. Therefore, the negative terminal of the error amplifier EA is not affected and is determined by the set value of the variable resistor VR1.

The drooping characteristic II is the change when the phototransistor of the photocoupler PC-I changes from ON to OFF, that is, the falling characteristic of the variable 3-terminal regulator shown in FIG. 3C from ON to OFF. Based on the change in the degree of conduction during the transition from the conducting state to the non-conducting state of the phototransistor in the photocoupler. This change occurs in a range in which the arc voltage drops to some extent, that is, in a change from V2 to V3. The phototransistor shifts from ON to OFF when the arc voltage drops, that is, in the range of V2 to V3, and is given as the reference signal potential of the minus terminal of the error amplifier EA by the change of the collector voltage at that time.

The second constant current characteristic III is that the phototransistor of the photocoupler PC-I is turned off and the difference between the variable resistor VR20 and mainly the resistor R3 and the variable resistor VR20 is given to the minus terminal of the error amplifier EA. Obtained by piezoelectric voltage. This occurs when the arc voltage drops from V3 to VS.

As described above, while the phototransistor in the photocoupler PC-I is on, the reference signal of the error amplifier EA is the first constant set by the variable resistors VR1 and VR2 and the variable three-terminal regulator REG1. It is equivalent to the current arc characteristic, but because the phototransistor in the photocoupler PC-I turns from on to off,
According to the change, the first constant current characteristic I 1, the drooping characteristic II and the second constant current characteristic III are combined to obtain the characteristic according to the present invention.

Then, from the first constant current characteristic I to the drooping characteristic
The transition point P1 to II corresponds to the point where the anode-cathode voltage VA-K in Fig. 3 (c) is approximately 2.5V, and the transition point P2 from the drooping characteristic II to the second constant current characteristic III is shown in the figure. This corresponds to the point where the anode-cathode voltage VA-K in 3 (c) is about 1.0V.

FIGS. 5A and 5B show the adjustment contents of the output voltage-output current characteristic shown in FIG.
FIG. 5A shows the transition of the transition point P1 when the transition point P1 between the characteristics of the first constant current characteristic portion I and the drooping characteristic portion II is changed.
(B) shows the transition of the transition point P2 when changing the inter-characteristic transition point P2 between the drooping characteristic section II and the second constant current characteristic section III.

The first constant current characteristic portion I is constant or almost constant at the current I1 set by the variable resistor VR1, and the second constant current characteristic portion III is set by the variable resistor VR20. I2 is constant or almost constant. Then, the drooping characteristic part II has a transition point P1 between the characteristics of the first constant current characteristic part I.
And the transition point P2 between the characteristics of the second constant current characteristic section III. The transition point P1 is parallel by adjusting the variable resistor VR10, as shown in FIG. 5A, and the transition point P2 is parallel by adjusting the variable resistor VR20, as shown in FIG. 5B. It can be moved.

As a result of such adjustment, the first constant current characteristic portion I 1 is based on the adjustment of the variable resistor VR1. Further, the transition points P1 and P2 are moved in parallel between Eros or between Hani by adjusting the variable resistance VR10 or VR20.

Therefore, if the first constant current characteristic portion I is set to the arc current I1 by the variable resistor VR1, the first constant current is adjusted by adjusting one or both of the variable resistors VR10 and VR20. The inter-characteristic transition voltage between the characteristic and the drooping characteristic to be combined therewith, and the inter-characteristic transition current between the drooping characteristic and the second constant current characteristic can be arbitrarily selected.

Since the drooping characteristic can be arbitrarily combined with the two constant current characteristics of the first constant current characteristic section I and the second constant current characteristic section III as described above, it is possible to use the high constant characteristic generally used in foreign countries. When performing welding with a short arc length for a cellulosic coated welding rod, it is possible to arbitrarily set the inter-characteristic transition point P1 to the appropriate drooping characteristic and the inter-characteristic transition point P2 to the short-circuit current, Good welding can be performed easily. As a result, it is possible to prevent arc breakage and sticking of the welding rod and the base material, and to suppress spatter to a minimum,
Good welding can be performed with good workability. [Modification]
Although the variable 3-terminal regulator is used in the above embodiment,
Alternatively, a well-known circuit configuration using a Zener diode may be used. Further, in the above-mentioned embodiment, the invention is applied to the welding machine by the phase control of the thyristor as the control element for the output control, but the output of the welding generator is rectified and the rectified output is changed by the chopper control of the transistor, the IGBT and the like. Of course, it can be applied to a welding machine having a circuit configuration.

Further, the variable resistors VR1, VR10, VR20 for various adjustments in the above embodiment may be external or internal to the control box.

[0040]

As described above, according to the present invention, the output characteristics of the arc welding machine are combined by combining predetermined drooping characteristics with respect to certain constant current characteristics at an arbitrary voltage, so that various coatings can be obtained. It is possible to provide an output characteristic suitable for the welding rod.

Two constant current characteristics, one of which corresponds to an arc current and the other of which corresponds to a short-circuit current, are connected by a drooping characteristic between arbitrary points of the two, thereby adapting to a wide variety of coated welding rods. A welding machine can be provided.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention.

2 (a) is a partial circuit diagram showing a circuit configuration example of only a component part for adjusting the welding machine output characteristic in the circuit of FIG. 1, and FIG. 2 (b) is one part of FIG. 2 (a). The partial circuit diagram which shows the example which changed the part.

3A is an equivalent circuit diagram of a variable three-terminal regulator, FIG. 3B is a control signal voltage-anode-cathode voltage characteristic diagram, and FIG. 3C is the same from on to off. Fall characteristic diagram.

FIG. 4 is a characteristic diagram showing the content of adjustment of output voltage-output current characteristics in the partial circuit of FIG.

5 (a) and 5 (b) are characteristic diagrams showing the adjustment contents of the output voltage-output current characteristic shown in FIG.

[Explanation of symbols]

G welding generator SCR thyristor D diode CT DC current transformer L reactor Output terminal for P and N welding PC photo coupler VR variable resistor R resistance C capacitor REG variable 3 terminal regulator EA error amplifier CP comparator

Front page continuation (72) Inventor Shunichi Shunichi 2-8-65 Yoshinodai, Kawagoe City, Saitama Denyo Co., Ltd. Saitama Factory (56) Reference JP 5-185226 (JP, A) JP JP 7-112275 (JP, A) JP-A-6-328247 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B23K 9/073 H02M 9/00

Claims (3)

(57) [Claims] 1. A welding generator driven by an engine, an output circuit for controlling the output of the welding generator according to a control signal and supplying the output to the welding output terminal, and a current flowing through the welding output terminal. A current detector that detects the error, an error detector that compares the output of the current detector with a reference signal to detect an error, and the control signal is formed in accordance with the output of the error detector and applied to the output circuit. A control signal forming circuit and a voltage detector for detecting the voltage applied to the welding output terminal are provided, and constant current control arc characteristics based on the reference signal are provided, exhibiting drooping characteristics near the arc voltage, and a decrease in arc voltage. Sometimes in an engine-driven arc welder having a constant current characteristic with increased current, with an adjustment circuit that determines the magnitude of a reference signal to be given to the error detector according to the output of the voltage detector. There is, before
Corresponding to the arc current by changing the reference signal
Between the constant current control arc characteristic and the drooping characteristic
It is equipped with an adjustment circuit that makes the voltage at the transition point variable, and the arc current is changed by changing the reference signal.
Of the corresponding constant current control arc characteristics and the drooping characteristics
An engine-driven arc welding machine characterized in that the voltage at the transition point between characteristics is variable. 2. A welding generator driven by an engine, an output circuit for controlling the output of the welding generator according to a control signal and supplying the output to the welding output terminal, and a current flowing through the welding output terminal. A current detector that detects the error, an error detector that compares the output of the current detector with a reference signal to detect an error, and the control signal is formed in accordance with the output of the error detector and applied to the output circuit. A control signal forming circuit and a voltage detector for detecting the voltage applied to the welding output terminal are provided, and constant current control arc characteristics based on the reference signal are provided, exhibiting drooping characteristics near the arc voltage, and a decrease in arc voltage. Sometimes in an engine-driven arc welder having a constant current characteristic with increased current, with an adjustment circuit that determines the magnitude of a reference signal to be given to the error detector according to the output of the voltage detector. There is, before
By changing the reference signal, the drooping characteristic and short circuit
Characteristic shift with the constant current control arc characteristic corresponding to the current
It includes an adjusting circuit and variable current row points were the current characteristics between the transition point between the constant current control arc characteristic corresponding to the short-circuit current and the drooping characteristic variable by varying said reference signal An engine-driven arc welder characterized by the following. 3. The engine-driven arc welding machine according to claim 1, wherein the adjustment circuit changes the reference signal.
With the constant current control arc characteristics corresponding to the arc current
With the variable voltage characteristic between the transition point between the drooping characteristic, the droop JP by changing the reference signal
Characteristic and the constant current control arc characteristic corresponding to the short circuit current
Engine-driven arc welder with variable current at the transition point between the characteristics .