KR100284597B1 - Inverter welding machine for arc and gas welding and its welding method - Google Patents

Abstract

The present invention relates to an inverter welder for arc and gas welding and a welding method thereof. Inverter welding machine for arc and gas welding, the first and second rectifier, single-phase voltage inverter, transformer, coupling reactor, drive unit, waveform control unit, PWM circuit, amplification circuit, D / A conversion circuit, central processing unit, voltage current An inverter welding machine composed of a detector, a welding condition setting unit, and a welding parameter setting unit includes an input gas detection unit that detects an amount of gas to be input and outputs a resultant detection signal to the central processing unit. The welding method of the inverter welding machine for arc and gas welding includes the steps of initializing the welding machine, checking the mode, and performing the mode checking step, in the welding mode, setting and storing the welding current and the welding voltage. And after the gas welding, the process goes back to the mode check step. The present invention can perform the work by using both arc welding and gas welding, and is suitable for a moving or special working environment.

Description

Inverter welder for arc and gas welding and its welding method

The present invention relates to an arc and gas combined welding machine capable of simultaneously performing inverter arc welding and gas welding. In particular, the present invention relates to an inverter welder for arc and gas welding and a welding method thereof.

In general, welding is a technique for cutting and joining metals using heat or pressure, and is widely used in electric and electronic product manufacturing and general industrial fields. The development trend of such welding is the trend of high quality, high precision, multifunction, unmanned and automated according to the development of power electronics and consumer's demand, and the reduction of spatter in the workplace is required.

Therefore, in order to improve the welding performance and quality, the development and control elements of the welding power source are required, and the research on the inverter arc welder adopting the inverter circuit in the welding machine system has been actively conducted in the AC arc welder in the early stage of the welding machine development.

The main concern of welding is the urgent need for high quality welding due to the high quality of welding, the development of new resources and the development of new methods of energy.

In addition, the progress of high quality materials is inevitably followed, which is expected to help diversify welding technology, guarantee stability, widen use environment, and develop new materials and new technologies.

Inverter controlled welding machine has better features than conventional thyristor controlled welding machine, so the demand is increasing day by day, but technical cooperation with foreign countries is dominant, and large-capacity (over 350A) control part is almost dependent on imports. I can't.

The inverter arc welding machine can significantly reduce the size of the transformer and the output reactor through the high frequency switching, and the output current is directly controlled by the control of the inverter to achieve the stability of the arc. Compared to this, there is an advantage that the use can be significantly increased.

In addition to directly controlling the output current of the inverter system of the welding machine, and in the event of an abnormality during welding in the welding machine, the instantaneous control using the microprocessor to enable the protection function to pursue the flexibility and variety of functions.

In order to weld a material based only on the type of metal by the general welding in which the metal and the melting point are joined by heating using an additive metal having almost the same melting point, it is necessary to select electric welding or gas welding according to the type of welding or the environment of the base metal. Have

Electric welding machines are usually a single-phase secondary circuit, and a lot of voltage transformers are used. However, this method can generate a lot of reactive power not only in the electric folding part but also in the supplied power line part depending on the base metal or the metal state to be welded, and also due to the increase of noise, it is possible to use a welding machine or a nearby OA device or FA. Harmonic disturbances can also be caused in computer systems and communication systems such as personal computers. And, according to the use it is necessary to develop a welding machine that can use these two welding together.

Domestic welding technology is in the past stage of advanced countries, that is, the size of the structure and the speed of welding speed are high. In the welding equipment, the advanced countries are mainly made of high quality inverter control welding machine, but in Korea, SCR control, general arc and gas welding machine, Resistance welding machines are only produced.

However, most of these products are of low quality, and in recent years, they are trying to produce inverter controlled welding machines.

Inverter arc welding machine can significantly reduce the size of transformer and output-side reactor (r-eactor) through high frequency switching, and can improve the stability of the arc because the output current is directly controlled by the control of inverter. Compared to this, the use can be significantly increased.

On the other hand, if nonlinear noise generated in the arc during welding flows into the primary side of the transformer, the switching element may be destroyed.

And although special welding is needed according to the base material of a welded material, most use an electric welder. The electric welder becomes large and heavier when the capacity becomes larger, and when a lot of noise and propagation disturbances are severe, it may also cause a short circuit on the power supply side.

This problem can be sufficiently solved by adopting the scheme according to the invention. Electric welding machines are diversified from tens of thousands to tens of thousands, but may vary according to the use of the workplace.

The main concern of welding is that the demand for high quality welding is more urgent as the key to high quality welding, development of new energy method and practical application. In the early 80's, an inverter control type was developed using SCR as an address.

However, due to the generation of harmonics on the power supply side, this system is gradually being developed as a PWM control type inverter system.

The general AC arc welding machine spread in Korea makes up most of the main, and if the AC arc welding machine is replaced by the inverter welding machine according to the present invention, it contributes to the quality improvement of the product.

On the other hand, the quality of SCR control, general arc and control welding machines produced in Korea is low, and the production of inverter control welding machines is being attempted by small and medium enterprises mainly in small companies.

Therefore, the main concern of welding is that the demand for high quality welding is more urgent due to the high quality of welding, the development of new energy method and practical use, and the welding conditions for each work, adjustment of parameters, productivity improvement, process Improvements in sales and labor costs are reduced by 10-15%.

Next, the welding background is as follows. When assembling metal machines or structures, it is sometimes necessary to join metal parts separately. In this case, rivets and bolts were mainly used, but in recent years, welding has been widely used to save materials, reduce weight, and increase production speed.

Welding means a method of joining by heating, melting, cooling and solidifying a joined portion of a metal. For welding, high-temperature molten iron generated by overlapping a metal heated to a high temperature, then tapping with a hammer or heating by a roller die, etc., and igniting a mixture of aluminum and iron oxide powder causes a chemical reaction. Such as thermite welding (thermit welding), which is injected into and welded to the welding, the gas welding which heat-welds the spark of gas or the spark of oxygen acetylene to the joint, and the electric welding referred to here.

Electrical welding refers to a method of electrically heating a joint, and may be classified into three types, such as resistance welding, induction welding, and arc welding, depending on the heating method.

Arc welding belongs to fusion welding because it completely dissolves and joins the joint, and the remaining two belong to pressure welding because of welding under pressure. Arc welding can be classified into two types, one is coated arc welding and the other is gas metal arc (GMA) welding. The former is a very agile welding method in which a welding rod is placed in a holder, and a direct arc or high current is applied to a base metal, and the welding rod and the base are fused and fused together while producing a strong arc and high heat. to be. The latter is shielded gas and carbon dioxide gas ( Co ₂ ) This welding method uses a wire containing special components as a filler material by flowing a mixed gas containing carbon dioxide or carbon dioxide to block the welding part from the atmosphere so that blow holes are not generated. The shielding gas has a great effect on the arc's electrical and thermal characteristics, bead shape, and the metallurgical properties of the molten metal. Co ₂ , MAG and MIG.

There are two types of wires. One is a solid wire with appropriate chemical composition, and is the most widely used wire from thin plate welding to electric field welding and thick plate welding. Another one is a flux cored wire to which deoxidizer, alloying element and flux are added.

Among the welding methods currently used in the industrial field, the coated arc welding method has decreased by more than 50% in the last 10 years and currently occupies about 25%. GMA welding, on the other hand, is stretched by 50% or more and occupies about 65% or more. This indicates that automation of arc welding is underway throughout the industry.

Arc arc welders include a DC arc welder and an AC arc welder. First, the DC arc welder will be described as follows.

For DC arc welding, it is also possible to obtain a drooping characteristic by connecting a series resistor to a 50 to 70 [V] DC constant voltage power supply.However, the loss of power in the resistor is very large, so a special DC generator with external characteristics is directly connected to the three-phase induction motor. Use one welder.

As generators, tahedral lottery generators, 203 brush generators, series Rosenberg generators, etc. are used, but recently, a welder in which a series reactor is inserted into the AC side using a dry rectifier is also used.

Next, an AC arc welding machine is demonstrated. AC arc welding machine can obtain the drooping characteristic by reactance, so it is possible to connect the reactor to the secondary side of the transformer or use the magnetic leakage transformer to obtain the necessary characteristic.

The transformer is a movable toe type, which moves one coil up and down to adjust the reactance, and as a movable iron type, fine current can be adjusted by moving the iron core in addition to the adjustment by the tap.

As a rating, 200, 300, 400, and 500 [A] things are produced. The power factor is generally very low, such as 40 [%].

For this reason, there is also a welding machine that puts a capacitor on the primary side to improve the power factor. Moreover, the efficiency is also low, usually about 70 to 80 [%]. In particular, when it is necessary to stabilize the arc, a method of increasing the conductivity of the arc space by overlapping high frequency and high voltage is also used.

Since welding systems are generally used in poor environmental conditions such as high temperature, high humidity, dust, etc., it is necessary to reduce the control part in order to be minimized in such an external environment, and use arc and gas in combination with welding conditions. There is a case to do it.

A general welding machine performs welding in which arc and gas are separated, and an AC arc, MIG, TIG, etc. mainly constitute a power supply centered on SCR, or a full bridge mainly using a power diode. ) Method is generally adopted.

Firms whose main products are conventional plant products account for the power loss caused by the welding machine, that is, the generation rate of reactive power is 30-40%, and the power factor is extremely low.

In order to improve this part, significant improvement can be achieved by adopting PWM control (PWM converter control) method.

As the arc welding power source, both bridge and DC are used. In the case of direct current, the base metal is the anode. When the current is extremely small, it exhibits negative characteristics and the voltage decreases as the current increases. In the current of 100 [A] or more, which is usually used for welding, the arc voltage is almost constant if the arc length is constant.

In order to stably connect the arc current to maintain a constant current, the external characteristic curve of the power supply must be a drooping characteristic. Normally, the arc voltage when welding with proper arc length is 20 to 35 [V], but the no-load voltage, that is, the maximum voltage of the welding power supply is 50 to 70 [V] for direct current and 70 to 100 [V] for alternating current. It is about.

Moreover, in the case of an AC arc of 50 A or less, since it is easy to become unstable especially, a no load voltage may be set to about 140 [V].

Next, when a DC arc and an AC arc are compared, it is as follows. AC is twice unstable at 1 [Hz] and the arc is unstable, but DC is inherently more stable. In addition, the direct current can select the polarity appropriately, and is particularly advantageous for the welding of a small current which is easy to break arc.

However, in practice, the covering material of the electrode has advanced, and at about 100 [A] or higher, the alternating current and the direct current are almost the same in the stability of the arc. At 100 [A] or higher, the arc easily disappears due to the phenomenon of magnetic blowout in DC and becomes unstable, but in AC, the magnetic field near the arc is weakened by the eddy current in the metal. In exchange is rather excellent.

Also, in the structure of a welding machine, there are many motor generator types in direct current, which is much more expensive and requires more power than an AC welding transformer, and therefore it is generally preferable to use an AC welding machine.

The power factor and efficiency of the AC arc welder are given by the following equation.

Table 1. Specification of welding machine

Kinds Rated secondary current (A) Rated utilization rate (%) Rated load voltage 2nd highest no-load voltage (V) Secondary current Available electrode diameter (mm) Resistance drop Reactance drop Maximum value (A) Minimum value (A) 50 Hz 60 Hz AW200 200 40 30 0 85 or less 200 or more 220 or less 35 or less 2.0 to 4.0 AW300 300 35 0 300 or more330 or less 60 or less 2.6 to 6.0 AW400 400 40 0 400 or more and 440 or less 80 or less 3.2 to 8.0 AW500 500 60 40 10 12 95 or less 500 or more550 or less 100 or less 4.0-8.0

Next, the arc welding and gas welding power supply unit will be described.

First, an inverter welding machine will be described.

Inverter-type welding machines, which appeared in the early 1980s, converted the conventional thyristor welding machine to control welding power at a speed of several hundred Hz to high-speed control of several tens of KHz. Direct control of physical phenomena is made possible.

Therefore, the parts to be developed are divided into three parts: the power supply part, the inverter part, and the output side coupling part.

First, in the power part, commercial power is usually used. Since the conventional method is a moving coil type or a moving iron type, an accident occurring in the welding part directly affects the power supply side. Short circuit accidents can be prevented.

Secondly, in the inverter section, short circuit condition is not allowed during welding, so no inrush current of the load or voltage drop due to short circuit should occur.

The inverter unit may be configured of a single-phase voltage inverter using an IGBT, a power transistor, or a GTO, and may control a system capable of synchronizing with a power supply using a microprocessor.

Such an inverter unit has the following functions regardless of the load condition.

1. Voltage control according to load variation

2. Harmonic current mitigation by load current (by welding part)

3. Reactive Power and Noise Reduction

Third, since the output part is a part that is actually making a product, a transient current fluctuation occurs when the output impedance is relatively high and the load changes rapidly.

Although the actual inverter is a voltage type, it can be seen that it is maintained by the current operation, so the welding state of the output is a short circuit or the same state, so a large short-circuit current can affect the primary side of the output transformer. You can use to mitigate abrupt changes in current.

The configuration of the whole system is difficult to develop in a short period of time, it is possible to commercialize in consideration of the condition and capacity of the workplace.

Next, gas welding is demonstrated. The advantage of gas welding is that the inert gas protection and constant temperature are usually maintained, and excellent shielding can be achieved by the concentrated arc supplied by the electrode, so that the shielding is excellent. Argon and helium gases are mostly used to completely shield the weld from the atmosphere in gas tungsten arc welding.

These gases are inert gases. Therefore, in order to protect the weld, filler material, and tungsten electrode from oxygen, nitrogen, and hydrogen in the atmosphere during welding, the inert gas is shielded to cover and block the weld.

Opaque inert gas shielding eliminates the need for solvents and also makes slag-free welds. As such, no removal of slag between the layers or after welding is completed.

There is no slag covering at the welds, and also fewer defects due to slag incorporation and intervention. Since gas tungsten arc welding usually does not show smoke or sparks, it is easy to observe the scene in which the weld is welded.

As a result, a good cross section and appearance are obtained, and a cleaner weld portion is formed, so that spatter is hardly generated. There is no need to remove spatters and slags, which makes welding finishing very easy and inexpensive.

Since the heat concentration is good, the arc forms a very narrow heat affected zone (HAZ) and therefore has less shear deformation, alloy segregation and residual stress.

In addition, a competent welder can easily polish a variety of welds of different metals in all positions, complicated equipment, expensive equipment, and frequent breakdowns.

One mile per hour cross airflow 0.5 mm / sec, a reasonable distance from the wind or an air barrier must be installed. A schematic diagram of a general arc welder and a gas welder is shown in FIG. 2.

Tungsten arc welding uses an electric arc to generate heat between a tungsten (or tungsten alloy) electrode and a base material to weld using heat, which protects the weld and the electrode from inert gas through a welding torch from a gas bottle. The flow is continued to protect the weld from air pollution.

Tungsten electrodes are only used to generate arcs and filler metal is supplied by hand holding the filler rod, or automatically wound around the filler wire with a spool. Supply.

As such, a tungsten electrode is considered nonconsumable, although it is periodically replaced. In addition, gas tungsten arc welding requires the following devices.

① AC (AC) or DC (DC) constant current welding machine

② Welding Torch (for tungsten electrode holding and inert shielding gas supply)

③ tungsten or tungsten alloy electrode

④ Flow regulator for inert gas supply pressure regulator and shielded gas flow rate

Table 2. Comparison of Elements with Different Currents

Since most arc heat is concentrated on electrodes with direct current reverse polarity, the electrodes used for direct current reverse polarity are much larger than those used for direct current positive polarity at the same current value. The electrode also consumes faster to make direct current reverse polarity.

If too thin an electrode is used, the electrode tip melts, damaging the tip appearance and contaminating the weld. Metals such as aluminum and magnesium are mainly welded by gas tungsten arc welding.

However, it causes hard, but poorly conducted, surface oxidation at the welding temperature. These oxidation phenomena disrupt the electron flow and make the arc unstable.

As shown in Table 2, in direct current reverse polarity, electrons flow in the direction of the electrode from the workpiece, and apparently, charged ions flow from the electrode to the workpiece.

The cation impacts the oxidation of heat-resistant surfaces and strikes the weld surface for clean action.

Figure 4 is a block diagram showing the configuration of the arc-type electric welder using a voltage inverter of the contents of the present invention filed in the name of the type of the electric welding machine using a voltage inverter and its welding method on September 27, 1997.

A summary of FIG. 4 is as follows. As shown in FIG. 4, an arc type electric welding machine using a voltage inverter includes a three-phase rectifying diode and a snubber circuit, and includes a power supply unit 100 for converting three-phase AC power into a DC power supply, and the power supply unit 100. Inverter unit 200 to control the voltage according to the load change by inputting the DC power supply, to mitigate the harmonic current caused by the load current, to reduce the reactive power and noise, and to control the system that can be synchronized with the power supply, coupling reactor It is composed of an output unit 300 to mitigate the sudden change of the current using.

That is, a commercial power source is usually used as the power supply unit 100. In the conventional movable coil type or movable iron core type welding machine, an accident occurring at the weld portion immediately affected the power supply side. However, since the inverter unit 200 is included in the configuration of FIG. 4, a short circuit accident can be prevented with a current and voltage sensing device. In addition, since the short circuit state is not allowed during welding in the inverter unit 200, the voltage drop due to the inrush current or the short circuit of the load should not occur.

Thus, the structure of the inverter unit 200 is configured by using an IGBT, a power transistor, or a GTO to configure a single-phase voltage type inverter, and to control a system capable of synchronizing with a power source using a microprocessor. The inverter unit 200 has the following function regardless of the load state.

-Voltage control according to load change

-Harmonic current mitigation by load current (by welding part)

Reactive Power and Noise Reduction

Next, since the output unit 300 is a part that is actually making a product, a transient current fluctuation occurs when the output impedance is relatively high and the load change is fast.

Although the actual inverter is a voltage type, it can be seen that it is maintained by the current operation, so the welding state of the output is a short circuit state. This type of large short-circuit current can affect the primary side of the output side transformer, so in the present invention, the coupling reactor is used to mitigate the sudden change in the current.

The inverter of the power supply unit on the main power supply side of the welding machine was configured as a single phase inverter using an IGBT element as an addresser. The drive circuit of this inverter was comprised using EXB841. In particular, the PWM control method is adopted to remove harmonics that may occur on the power supply side. However, the arc-type electric welding machine using the voltage inverter of the above configuration has a problem that can not combine arc and gas welding.

The present invention has been made to solve the above problems, and developed a high-performance inverter control welding machine at a low capacity, gradually increasing the capacity based on the experience, high performance, sex energy, stability, maximization of the use environment range, new materials and Its purpose is to provide inverter welding machine which can combine arc and gas welding superior to existing SCR method by focusing on the development of new technology.

It is another object of the present invention to provide a welding method for an inverter welder for arc and gas welding.

1 is a graph showing an external characteristic curve of voltage and current.

2 is a configuration diagram of a gas tungsten electrode arc welder.

3 illustrates a tungsten arc welding method.

Figure 4 is a block diagram showing the configuration of an arc-type electric welder using a conventional voltage inverter.

Figure 5 is a block diagram showing the configuration of the inverter welding machine for arc and gas welding of the present invention.

Figure 6 is a flow chart showing the flow of the welding method of the inverter welding machine for arc and gas welding in accordance with the present invention.

7 is a waveform diagram of an input voltage and an input current of an arc welder in operation.

8 shows waveforms at the time of welding;

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. Figure 5 is a block diagram showing the configuration of the inverter welding machine for arc and gas welding of the present invention. As shown in Figure 5, the arc and gas welding inverter welding machine of the present invention, the first and second rectifiers, single-phase voltage inverter, transformer, coupling reactor, drive unit, waveform control unit, PWM circuit, amplifier circuit, D In an inverter welding machine comprising a / A conversion circuit, a central processing unit, a voltage current detection unit, a welding condition setting unit, and a welding parameter setting unit, an input gas detection unit which detects an amount of gas to be input and outputs the resultant detection signal to the central processing unit. And (28). As the input gas detector 28, a gas sensor is used.

In the welding method of the inverter welding machine for arc and gas welding of the present invention, the step of initializing the welder, checking the mode, performing the mode check step, if the welding mode, and setting the welding current, the welding voltage and storing them After the arc and gas welding, the step of going back to the mode check step is made.

In the welding method of the inverter welding machine for arc and gas welding according to the present invention, if the setting mode is the result of performing the mode checking step, selecting the welding parameter to be set, setting the welding parameter, and then going back to the mode checking step. It further comprises a step.

Next, the electric current relationship at the time of welding is demonstrated as follows. In gas-shielded metal arc welding, the weld line has a function of one electrode of the arc, and is fused by arc heat to form a weld metal.

Most of the heat contributing to the melting of the welding line is supplied by the heat generation of the tip portion by the arc. This calorific value is proportional to the product of the welding current and the welding voltage. When there is almost no change in the welding voltage, the heating value, that is, the welding output power, is proportional to the welding current.

The welding current is the ability to melt the wire and the base material to be fed, and it has a great influence on the melt rate, penetration, and work efficiency of the wire.

Next, the operation mode at the time of welding is as follows.

First, as a welding mode, this welding mode is a mode in which welding can be performed with welding condition setting and set current and voltage.

Secondly, as a welding parameter setting mode, this mode can set various parameters related to welding.

Third, as an operation mode, this mode is achieved by simultaneously operating a switch between a welding mode and a welding parameter setting mode.

That is, the voltage current detector 28, the PWM circuit 24, and the waveform controller 23 automatically widen the pulse width of the inverter when the welding current becomes lower than or equal to a predetermined value, so that the welding current does not become lower than or equal to the predetermined value. Perform control.

When the change in the input power detected by the voltage current detector 28 is input outside the proper operating range, the PWM output is immediately interrupted, the central processing unit 27 is stopped, and the error lamp is turned on.

In addition, since the short circuit state is not acceptable during welding in the inverter unit 201, the voltage drop due to the inrush current of the load or the short circuit should not occur. Thus, the inverter unit 201 is configured using an IGBT, a power transistor, or a GTO to configure a single-phase voltage inverter, and to control a system capable of synchronizing with a power source using a microprocessor.

The IGBT turns the PWM output off immediately when the junction rises above a certain temperature. Then, a circuit is provided to prevent the current flowing through the IGBT from exceeding the capacitance of the transistor and damaging the element.

PWM control method is adopted to remove harmonics that may be generated on the power supply side.

Next, FIG. 6 is explained in full detail. First, the welder is initialized (S1) and then the mode is checked. (S2)

As a result of performing the mode check step S2, in the welding mode, the welding current and the welding voltage are set and stored. (S3)

Then, after arc and gas welding, it goes back to the mode check step. (S4)

Then, as a result of performing the mode check step S2, if it is the setting mode, the welding parameter to be set is selected (S5), the welding parameter is set, and then the mode check step is performed again. (S6)

More detailed description is as follows.

First, after the power is supplied to the welding machine, it is operated in a welding state that allows welding work in an initializing state. Next, the switch can be operated simultaneously to operate the state with a switch capable of confirming and counting previously set welding parameters.

Then repeat the above steps to change the welding parameters after the operation.

When operating in the above state, it is possible to consider the case of simulating the operating state.

When high speed pulse (MIDDLE) is set, thin plate can be welded at high speed and fine beads can be obtained. When low speed pulse (LOW) is set, excellent performance is achieved for thick plate welding and wide welding.

7 is a diagram illustrating input voltage and current waveforms simulated during operation of the arc welder. 8 is a view showing waveforms at the time of welding.

Since the present invention is an inverter control, the input KVA 1/2, size 1/3, weight 1/5 compared to the conventional welding machine, so that it can be operated optimally and economically in the field workshop or small space, and the start-up current- Slop control prevents the melt at the start of thin plate welding and the lack of penetration at the time of thick plate welding, and the down-slop control at the end of welding enables the adjustment of the crater current, and prevents the melting of the finish and the cracking.

Compared with the inverter control welding machine and the existing SCR welding machine, it has the following advantages so that even beginners can easily weld.

1. Increasing the control frequency reduces the volume of the transformer, thereby reducing the size and weight.

2. As the control frequency increases, the stability of the arc is secured even in the low current region by controlling the current rate of increase in the short circuit, and the amount of spatter is reduced.

3. The welding performance in the automatic welding device is improved by controlling the waveform to stabilize the arc even at high speed welding.

4. The current rise time can be reduced at the start of the arc, which is advantageous for automatic welding.

5. It can store energy of rated input as compared with thyristor welding machine.

6. Gas welding can be performed easily according to the environment and work materials.

7. There is an advantage that both arc and gas welding can be used, but the structure of the facility has a disadvantage.

In addition, the work can be performed by the combination of arc welding and gas welding, which is suitable for a moving or special case working environment.

Claims (5)

1st, 2nd rectifier, single phase voltage inverter, transformer, coupling reactor, drive part, waveform control part, PWM circuit, amplification circuit, D / A conversion circuit, central processing part, voltage current detection part, welding condition setting part, welding parameter In the inverter welding machine composed of a setting unit, An inverter welder for arc and gas welding, comprising an input gas detector for detecting the amount of gas to be input and outputting the resultant detection signal to the central processing unit. Initializing the welder; Checking a mode of the initialized welder; Setting and storing a welding current and a welding voltage when the mode check result is a welding mode; And And arc and gas welding, and then going back to the mode check step. The method of claim 2, Selecting a welding parameter to be set if the mode check result is set mode; And And after the setting of the selected welding parameter, performing the mode check again. The welding method for an inverter welder for arc and gas welding according to claim 2, wherein the welding mode is a mode in which welding conditions are set and welding is performed with a set current and voltage. 4. The welding method of the inverter welder for arc and gas welding according to claim 3, wherein the setting mode is a welding parameter setting mode for setting various parameters related to welding.