JPH09201674A - Welding method and equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the welding performance at the start of welding and reduce shielding gas consumption in arc welding using shielding gases. SOLUTION: At the start of welding, a shielding gas is supplied that is excellent in welding performance and then, at the point of time with a stabled arc forming state, the gas supply is switched to other kind of shielding gas. For this purpose, the shielding gas supply device 4a is constituted of at least two kinds of gas supply sources 41a, 41b and a switching valve 44 capable of selecting at least two gas supply sources 41a, 41b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a welding method and a welding apparatus, and more particularly to an arc welding method and a welding apparatus using carbon dioxide gas or a mixed gas as a shield gas.

[0002]

2. Description of the Related Art In welding of steel materials, an arc welding method in which carbon dioxide gas or a mixed gas is used as a shield gas is widely used. The advantages of this welding method are that the mechanical properties of the welded part are as excellent as the welding method using a low hydrogen coated arc welding rod, high efficiency, large penetration, and welding in all positions. It is possible, it is a visible arc, etc. Carbon dioxide gas as a shield gas is characterized by being extremely inexpensive as compared with an inert gas or a mixed gas of argon or helium. The mixed gas has improved welding performance by adding another gas to carbon dioxide gas as compared with the case of carbon dioxide gas alone. As the mixed gas, a mixture of carbon dioxide gas with argon gas, a mixture of oxygen gas, a mixture of carbon monoxide gas, a mixture of argon gas and oxygen gas, and the like are used. For example, in a mixed gas of carbon dioxide gas and argon gas, the bead shape is improved, the amount of spatter is reduced, the arc temperature is increased, and the amount of penetration is increased. With a mixed gas of carbon dioxide gas and oxygen gas, the arc temperature rises, the melting rate of the wire increases, and the amount of penetration increases.

Conventionally, arc welding using this carbon dioxide gas or mixed gas as a shield gas has been carried out by a welding device having a structure as shown in FIG. That is, in FIG. 2, the welding device is configured with the welding machine 1 having a control function, the wire feeding device 2, the welding torch 3, and the shield gas supply device 4 as main components. The welding machine 1 is supplied with the shield gas from the shield gas supply device 4 through the first connecting pipe 7a, and the second connecting pipe 7 is supplied.
It is connected by piping so as to supply a shield gas to the welding torch 3 via b. Further, the welding machine 1 is
It is connected so as to supply a welding current to the welding torch 3 via the power cable 5a and to the workpiece 10 via the second power cable 5b. The wire feeding device 2 includes a wire reel 2 a, and a welding wire 6 is attached to the welding torch 3.
To supply. The shield gas supply device 4 further includes a gas cylinder (shield gas supply source) 41 filled with shield gas, a regulator 42 for adjusting the flow rate of the shield gas, and a third connecting pipe 43 for connecting the two devices. .

With the welding device configured as described above,
In the arc welding, a welding current is supplied from the welding machine 1 to the welding torch 3 and the workpiece 10 via the first power cable 5a and the second power cable, and the shield gas of the gas cylinder 41 is supplied to the third connecting pipe 43 and the regulator 42. And the first connecting pipe 7
The welding wire 6 is supplied from the welding machine 1 to the welding torch 3 via the second connecting pipe 7b while the flow rate is adjusted via a, and the welding wire 6 is supplied from the wire feeding device 2 to the welding torch 3. Is done.

[0005]

Since the conventional welding method and apparatus for arc welding using carbon dioxide gas or mixed gas as the shield gas are constructed as described above, the following problems exist. Was there. That is, welding is always performed using one type of shield gas. Therefore, when using carbon dioxide gas, from the start of welding until the state of arc formation is stable, penetration is insufficient and the bead shape is inferior, and the amount of spatter is large,
It may cause welding failure. Further, when the mixed gas is used, the problem as in the case of carbon dioxide gas does not occur even at the start of welding, but the mixed gas is expensive as compared with carbon dioxide gas, and the welding construction cost becomes high. Further, in the conventional welding apparatus, it is impossible to change the shield gas during the welding, that is, to replace the gas cylinder while continuing the welding without giving a sharp change to the welding conditions.

The present invention has been made to solve the above problems, and in arc welding using carbon dioxide gas or a mixed gas as a shield gas, a welding method for improving the welding performance at the start of welding at a low cost. And a welding device.

[0007]

In order to achieve the above object, in arc welding using a shield gas, the welding method according to the present invention provides a shield gas having good welding performance at the start of welding, It is characterized in that when the formation state becomes stable, another type of shield gas is switched and supplied.

More specifically, when the shield gas at the start of welding is switched to another type of shield gas, the supply of the other type of shield gas is stopped and then the supply of the shield gas at the start of welding is stopped. Is a welding method.

More specifically, the welding method is characterized in that the other type of shielding gas is carbon dioxide gas.

Further, in arc welding using shield gas, the welding device according to the present invention comprises a welding machine having a control function, a wire feeding device, a welding torch, and a shielding gas supplying device. In the welding device, the shield gas supply device includes at least two types of shield gas supply sources and a switching valve capable of selectively switching at least two types of gas supply sources. .

More specifically, the switching valve switches between at least two inflow ports and the outflow port to communicate with each other, and while switching the communication state between the outflow port and any two inflow ports. The welding device is characterized in that the outflow port and the arbitrary two inflow ports are communicated at the same time.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION A preferred embodiment of a welding method and apparatus for arc welding using a shielding gas according to the present invention will be described in detail below with reference to the drawings. FIG.
FIG. 1 is an overall configuration diagram of a welding device according to the present invention. In FIG. 1, the welding device includes a welding machine 1 having a control function, a wire feeding device 2, a welding torch 3, and a shield gas supply device 4.
a is a main constituent device. The welding machine 1
Is from the shield gas supply device 4a to the first connecting pipe 7a.
A shield gas is supplied through the pipe, and the pipe is connected so that the shield gas is supplied to the welding torch 3 through the second connecting pipe 7b. Further, the welding machine 1 is connected so as to supply a welding current to the welding torch 3 via the first power cable 5a and to the workpiece 10 via the second power cable 5b. The wire feeding device 2 includes a wire reel 2 a and supplies a welding wire 6 to the welding torch 3.

The shield gas supply device 4a further comprises two shield gas supply sources, that is, one mixed gas cylinder 41a filled with a mixed gas of carbon dioxide gas and argon gas having good welding performance at a high pressure and an inexpensive one. One carbon dioxide gas cylinder 41b filled with carbon dioxide at a high pressure, one switching valve 44, the switching valve 44 and the two gas cylinders 41
a fourth connecting pipe 43a, a fifth connecting pipe 45a, a sixth connecting pipe 43b, a seventh connecting pipe 45b and a fourth connecting pipe 43a, a fifth connecting pipe 45a, a sixth connecting pipe 43
b, a first regulator 42a and a second regulator 42b provided in the middle of the seventh connecting pipe 45b. The switching valve 44 is provided with one outflow port and two inflow ports, such as a three-way switching valve,
By the switching operation, the outlets are individually communicated with the respective inlets, and when the communication state is switched, the outlets and the two inlets are simultaneously communicated in the middle of the switching.

The case where welding is carried out by the welding device configured as described above will be described below. To start welding, first, the switching valve 44 connects the first connecting pipe 7a and the fifth connecting pipe 45a, and the stop valve (not shown) of the mixed gas cylinder 41a is opened to supply the mixed gas. The mixed gas is supplied from the mixed gas cylinder 41a to the welding torch 3 through the fourth connecting pipe 43a, the first regulator 42a, the fifth connecting pipe 45a, the switching valve 44, the first connecting pipe 7a, the welding machine 1, and the second connecting pipe 7b. Then, it is discharged from the tip of the welding torch 3 to the welding portion. The supply amount of the mixed gas is adjusted to a predetermined supply amount by operating the first regulator 42a. Next, the welding machine 1 is operated to start the supply of the welding current to the welding torch 3 and the workpiece 10 via the first power cable 5a and the second power cable, and at the same time, the wire feeding device 2 transfers the wire to the welding torch 3. The supply of the welding wire 6 wound on the reel 2a is started, and the welding of the workpiece 10 is started. The control function of the welding machine 1 corresponds to the welding conditions of the workpiece 10,
The feeding speed of the welding wire 6 supplied from the wire feeding device 2, the supply amount of the mixed gas, and the welding current are set and adjusted. Even in a state where the arc formation condition of the welding started in this way is unstable, the shielding gas is a mixed gas with good welding performance, penetration is sufficient, and the bead shape is good, The amount of spatter is small and good welding is performed.

After starting the welding as described above, the switching valve 44 is operated to switch the shield gas from the mixed gas to the carbon dioxide gas when the conditions for forming the arc and the state of the formed arc become stable. That is, carbon dioxide cylinder 41b
The stop valve (not shown) is opened to supply carbon dioxide gas. The regulator 42b is set to a predetermined supply amount, the switching valve 44 is operated, and the shield gas supplied to the connection pipe 7a is switched from the mixed gas to the carbon dioxide gas. At the time of switching, the supply amount of carbon dioxide gas gradually increases and the supply amount of mixed gas gradually decreases, so that the mixed gas and carbon dioxide gas are mixed and supplied while changing the mixing ratio thereof. The switching operation of 44 is performed. By this switching operation, the composition of the shield gas gradually changes from the mixed gas to the carbon dioxide gas at the welded portion of the object to be welded 10, and the sudden change in the properties of the shield gas, the pressure fluctuation or the pulsation due to the switching does not occur, which is excellent. A good welding condition is maintained. When the switching operation of the switching valve 44 is completed, the first connecting pipe 7a and the seventh connecting pipe 45b communicate with each other in a normal state, and the first connecting pipe 7a and the fifth connecting pipe 45a are shut off. Then, the stop valve of the mixed gas cylinder 41a is closed. After that, welding is continued in this state using carbon dioxide gas as a shield gas.

In the above description, the case where a mixed gas of carbon dioxide gas and argon gas and carbon dioxide gas are used as the two kinds of shield gas has been described, but the technique of the present invention is a mixed gas other than these. For example, carbon dioxide mixed with oxygen, carbon monoxide mixed,
The same can be applied to a case where a mixture of argon gas and oxygen gas or argon gas, helium gas, etc. (inert gas) is used as the shield gas, and the shield gas supply device is provided with three types and four types of shield gas. It is also possible to appropriately select and switch the shield gas according to the material of the object to be welded 10 or the welding conditions. The switching valve 44 at that time is provided with one outlet and at least three inlets, and the outlet is individually communicated with each inlet by the switching operation, and when switching the communication state. The outlet and the arbitrary two inlets can be simultaneously communicated. For example, one opening of each of three or more stop valves is connected as one outflow port, the other opening is independent as it is, and any two stop valves are independently adjusted while adjusting the opening degree. This can be done by opening and closing (while shutting off other stop valves during this period).

Further, although the operation of the switching valve has been described in the manual state, it is a technique that can be automated and is a technique that can be applied to a semi-automatic welding device or a fully automatic welding device. Furthermore, the technique of the present invention is not limited to welding of steel materials, but is also applied to metal materials other than steel materials on which arc welding using shield gas is performed.

[0018]

The welding method and apparatus for arc welding using a shielding gas according to the present invention are configured as described above, so that the following effects can be obtained. In other words, the shielding gas with good welding performance is supplied at the start of welding, and when the state of arc formation stabilizes, the shielding gas is switched to another type of shielding gas and supplied, so that the welding performance with poor welding performance is shortened. Supplying an expensive shield gas with good welding performance only during the time, and then supplying cheap shield gas with good welding performance, ensuring good welding performance from the start of welding, and then applying the shield gas for welding The cost can be reduced.

For example, when welding a steel material, by supplying a mixed gas at the start of welding and then supplying carbon dioxide gas, the penetration is sufficient from the start of welding, the bead shape is good, and spatter is generated. The quantity is small, and good welding performance that does not cause welding defects can be realized at low cost.

Further, when switching from the shield gas at the start of welding to another type of shield gas, by gradually switching while supplying both shield gases at the same time, a sudden change in the properties and pressure of the shield gas accompanying the switching can be achieved. No fluctuation or pulsation occurs and a good welding condition is maintained.

In the welding apparatus according to the present invention, since a plurality of shield gas supply sources are connected to a switching valve capable of selectively switching the gas supply sources, the shielding gas supplied by operating the switching valve is provided. It is possible to easily switch from one type to another.

Further, the switching valve gradually switches two types of shield gas by connecting two inflow ports and an outflow port for switching at the same time during the switching operation to gradually switch two types of shield gas. Smooth switching is possible without causing sudden changes in properties, pressure fluctuations, or pulsation.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing a welding device for arc welding using a shielding gas according to the present invention.

FIG. 2 is an overall configuration diagram showing a welding device for arc welding using a conventional shield gas.

[Explanation of symbols]

 1 Welder 2 Wire feeder 3 Welding torch 4 Shield gas supply device 4a Shield gas supply device 5a Power cable 5b Power cable 6 Welding wire 7a Connection pipe 7b Connection pipe 10 Welding object 41 Gas cylinder (shield gas supply source) 41a Gas cylinder (Shield gas supply source) 41b Gas cylinder (shield gas supply source) 42 Regulator 42a Regulator 42b Regulator 43 Connection pipe 43a Connection pipe 43b Connection pipe 44 Switching valve 45a Connection pipe 45b Connection pipe

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[Procedure amendment]

[Submission date] July 1, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0015

[Correction method] Change

[Correction contents]

After the welding is started as described above, the switching valve 44 is operated to switch the shield gas from the mixed gas to the carbon dioxide gas when the conditions for forming the arc and the state of the formed arc become stable. That is, carbon dioxide cylinder 41b
Supply carbon dioxide gas from the side . The regulator 42b is set to a predetermined supply amount, the switching valve 44 is operated, and the connection pipe 7a
The shield gas supplied to is switched from mixed gas to carbon dioxide gas. At the time of switching, the supply amount of carbon dioxide gas gradually increases and the supply amount of mixed gas gradually decreases, so that the mixed gas and carbon dioxide gas are mixed and supplied while changing the mixing ratio thereof. The switching operation of 44 is performed. By this switching operation, the composition of the shield gas gradually changes from the mixed gas to the carbon dioxide gas at the welded portion of the object to be welded 10, and the sudden change in the properties of the shield gas, the pressure fluctuation or the pulsation due to the switching does not occur, which is excellent. A good welding condition is maintained. When the switching operation of the switching valve 44 is completed, the first connecting pipe 7a and the seventh connecting pipe 45b communicate with each other in a normal state, and the first connecting pipe 7a and the fifth connecting pipe 45a are shut off. After that, the mixed gas cylinder 41a side is closed, and thereafter, in this state, welding is continued using carbon dioxide gas as a shield gas.

Claims (5)

[Claims] 1. In arc welding using a shield gas, a shield gas having good welding performance is supplied at the start of welding, and is switched to another kind of shield gas when the arc formation state is stable. Welding method characterized by. 2. When switching from the shield gas at the start of welding to another type of shield gas, the supply of the shield gas at the start of welding is stopped after the supply of the other type of shield gas is started. The welding method according to claim 1. 3. The welding method according to claim 1, wherein the other type of shield gas is carbon dioxide gas. 4. A shield gas comprising a welding machine (1) having a control function, a wire feeding device (2), a welding torch (3) and a shield gas supply device (4a) is used. In the welding apparatus for arc welding, the shield gas supply device (4a) can selectively switch between at least two types of shield gas supply sources (41a, 41b) and at least two types of shield gas supply sources (41a, 41b). And a switching valve (44). 5. The switching valve (44) switches at least two inflow ports and the outflow port to communicate with each other, and while switching the communication state between the outflow port and any two inflow ports. The welding device according to claim 4, wherein the outflow port and the arbitrary two inflow ports are communicated at the same time.