JPH0444311Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention relates to a switching mechanism that switches and supplies shielding gas and compressed air for preventing spatter adhesion to an arc welding torch. The present invention relates to a shield gas switching mechanism that prevents

[Prior Art] Some automatic arc welding machines used in automobile production lines and the like are equipped with an air circuit for blowing off spatter adhering to the inside of a welding torch.

FIG. 2 shows a switching mechanism for a shielding gas circuit in a conventional arc welding machine and an air circuit for removing spatter adhering to the inside of a welding torch. Second
In the figure, 1 indicates a shielding gas supply source, and a first electromagnetic valve 2 is connected to the shielding gas supply source 1. The outlet side of the first electromagnetic valve 2 is connected to a welding torch 4 via a gas passage 3.
Reference numeral 5 indicates a compressed air supply source, and a second electromagnetic valve 6 is connected to the compressed air supply source 5. Second
The outlet side of the solenoid valve 6 is connected to the gas passage 3.

In such a shield gas switching mechanism, only the first electromagnetic valve 2 is energized and opened during welding, and the shield gas is supplied to the welding torch 4. After welding is completed, the first solenoid valve 2 is turned off, and then the second solenoid valve 6 is energized and opened, and compressed air is supplied to the welding torch 4. As a result, spatter adhering to the inside of the welding torch 4 is blown away by the compressed air, and the welding torch is cleaned. Note that the shielding gas pressure is normally
It is set to 0.5~2Kg/ ^cm2 , and the air pressure is usually 3~2Kg/cm2.
It is set at 8Kg/ ^cm2 .

[Problems to be solved by the invention] Generally, when a small amount of air is mixed into the shielding gas, blowholes are generated in the welded part, causing problems such as strength problems and water leakage. In FIG. 2, if there is a gap in the seat surface inside the second electromagnetic valve 6 that controls the flow of air, there is a risk that air will get mixed into the shielding gas through that gap. In other words, if the seat surface of the second electromagnetic valve 6 is damaged due to intrusion of foreign matter such as dust, air leaking from the damaged portion will flow into the welding torch together with the shielding gas.

In addition, if there is a leak in the first solenoid valve 2 that controls the flow of shielding gas, for example, if the gas flow path in the welding torch 4 is clogged with spatters or the like during air blowing, and the pressure in the gas passage 3 increases. A problem arises in that air flows into the shielding gas supply source 1 side.

Focusing on the above problem, this invention prevents air from entering the shield gas even if a leak occurs in each solenoid valve, and switches the shield gas to obtain a high-quality weld bead without blowholes. The purpose is to provide a mechanism.

[Means for Solving the Problems] The shielding gas switching mechanism in arc welding of the present invention that meets this purpose has a first electromagnetic switch whose upstream side is connected to a shielding gas supply source and which supplies shielding gas to the welding torch during welding. a first check valve provided between the first solenoid valve and the welding torch and allowing shielding gas to flow only from the first solenoid valve to the welding torch; and an upstream side connected to a compressed air supply source. a second solenoid valve that supplies compressed air to the welding torch to remove spatter after welding is completed;
a third solenoid valve provided between the second solenoid valve and the welding torch and having a port open to the atmosphere; and a third solenoid valve provided between the third solenoid valve and the welding torch and having a port open to the atmosphere.
and a second check valve that allows compressed air to flow only from the solenoid valve to the welding torch.

[Function] In the shielding gas switching mechanism for arc welding configured in this way, the first
Only the first solenoid valve is energized and opened, and the shielding gas flowing out from the first solenoid valve is supplied to the welding torch via the first check valve. in this case,
The second solenoid valve and the third solenoid valve are in an off state. Since the second solenoid valve is connected to the welding torch side via the third solenoid valve, even if leakage occurs in the second solenoid valve, in this state,
The leaked air is discharged to the atmosphere through a port of the third solenoid valve that is open to the atmosphere. Further, since a second check valve is provided between the third solenoid valve and the welding torch, shielding gas is prevented from flowing into the third solenoid valve.

When welding is completed, the first solenoid valve is closed,
Voltage is applied to both the second solenoid valve and the third solenoid valve, and both valves are in an open state. This results in
Compressed air is supplied from the compressed air supply source to the welding torch through the second solenoid valve, the third solenoid valve, and the second check valve. In this case, even if a leak occurs in the first solenoid valve that controls the flow of shielding gas, the first check valve is provided between the first solenoid valve and the welding torch, so the first check valve The valve prevents compressed air from flowing back to the shielding gas side.

Therefore, both during and after welding,
Compressed air is prevented from entering the shielding gas, resulting in a high quality weld bead.

[Example] Hereinafter, a preferred example of the shielding gas switching mechanism in arc welding according to the present invention will be described with reference to the drawings.

FIG. 1 shows an embodiment of the present invention. In the figure, 11 indicates a shielding gas switching mechanism, 12 indicates a shielding gas supply source, and 13 indicates a compressed air supply source. A two-port, two-position type first solenoid valve 14 is connected to the shielding gas supply source 12 . The outlet side of the first solenoid valve 14 is
It is connected to a first check valve 16 via a passage 15. Furthermore, the first check valve 16 is connected to a welding torch 18 via a passage 17.
The first check valve 16 is arranged to allow shielding gas to flow only from the first solenoid valve 14 to the welding torch 18. The first solenoid valve 14 is opened when energized, and closed by a built-in spring when not energized. Therefore, the shielding gas is supplied to the welding torch 18 only when the first electromagnetic valve 14 is energized.

A second solenoid valve 20 of a two-port, two-position type is connected to the compressed air supply source 13 . The outlet side of the second solenoid valve 20 opens a passage 21 and is connected to a third solenoid valve 22 . Third solenoid valve 22
is a 3-port, 2-position type solenoid valve, and the passage 21 is opened to the atmosphere when the current is not energized. The outlet side of the third solenoid valve 22 is connected to the passage 2
3 to a second check valve 24. Further, the second check valve 24 is connected to the passage 25.
It is connected to the shielding gas passage 17 via. The second check valve 24 is connected to the third solenoid valve 22.
The welding torch 18 is arranged to allow compressed air to flow only from the welding torch 18 to the welding torch 18. The second solenoid valve 20 and the third
The solenoid valves 22 are energized at the same time and are configured to open when energized. When the electromagnetic valves are not energized, the springs built into each electromagnetic valve close the valves. Therefore, compressed air is supplied to the welding torch 18 only when both the first solenoid valve 20 and the second solenoid valve 22 are energized.

Next, the operation of the above-mentioned shield gas switching mechanism will be explained.

First, during welding, the first solenoid valve 14 is excited by electricity, and the first solenoid valve 14 is in an open state. Therefore, the shielding gas flows through the first solenoid valve 1
The welding torch 18 is supplied to the welding torch 18 through the passage 15, the first check valve 16, and the passage 17. In this case, the second solenoid valve 20 and the third
Since the electromagnetic valve 22 is de-energized, compressed air is not supplied to the welding torch. Here, even if there is a leak inside the second solenoid valve 20 and compressed air flows out from the outlet port of the second solenoid valve 20, the outlet port of the second solenoid valve 20 Since it is opened to the atmosphere via the valve 22, the leaked compressed air is released to the atmosphere and is not mixed into the shield gas side. Moreover, the passage 2 between the welding torch 18 and the third solenoid valve 22
Since the second check valve 24 is located at 5, shielding gas is also prevented from flowing into the compressed air side.

When welding is completed, the first electromagnetic valve 14 is de-energized, and the first electromagnetic valve 14 is closed. Thereafter, the second solenoid valve 20 and the third solenoid valve 22 are energized simultaneously, and compressed air is supplied to the welding torch 18. Spatter generated during welding is attached to the inside of the tip of the welding torch 18, and the attached spatter is blown off by the compressed air, thereby cleaning the inside of the tip of the welding torch 18.

Here, suppose there is a leak in the first solenoid valve 14,
If the gas passage in the welding torch 18 is clogged, the pressure in the passage 17 will increase, and there is a risk that compressed air, whose pressure is set higher than that of the shielding gas, may flow into the shielding gas supply source 12. but,
The first check valve 16 provided between the first electromagnetic valve 14 and the welding torch 18 is connected to the welding torch 18.
Since the structure does not allow flow from the side toward the first electromagnetic valve 14, backflow of compressed air toward the shield gas side is reliably prevented.

In this way, even if a leak occurs in the first solenoid valve 14 and the second solenoid valve 20, the situation where compressed air gets mixed into the shielding gas is reliably prevented, and pure shielding gas is supplied to the welding area. only is supplied.

[Effect of the invention] As explained above, when using the shield gas switching mechanism in arc welding of the invention, even if air leaks from the second solenoid valve during welding, the leaked compressed air is transferred to the third solenoid valve. Since the gas is discharged to the atmosphere via the solenoid valve, it is possible to prevent compressed air from entering the shield gas. In addition, since the first check valve is provided between the first solenoid valve and the welding torch, backflow of compressed air to the shielding gas supply side during air blowing is prevented, and similarly compressed air to the shielding gas is prevented from flowing back to the shielding gas supply side. Contamination is prevented. Therefore, no air is mixed into the shielding gas, and a high-quality weld bead without blowholes can be obtained.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a shield gas switching mechanism in arc welding according to an embodiment of the present invention, and FIG. 2 is a schematic diagram of a shield gas switching mechanism in conventional arc welding. 12... Shield gas supply source, 13... Compressed air supply source, 14... First solenoid valve, 16... First
18... welding torch, 20... second solenoid valve, 22... third solenoid valve, 24... second check valve.

Claims (1)

[Scope of utility model registration request] a first solenoid valve whose upstream side is connected to a shielding gas supply source and supplies shielding gas to the welding torch during welding; a first check valve that allows shielding gas to flow only to the welding torch; a second solenoid valve whose upstream side is connected to a compressed air supply source and supplies compressed air to the welding torch to remove spatter after welding is completed; a third solenoid valve provided between the solenoid valve and the welding torch and having a port open to the atmosphere; and a third solenoid valve provided between the third solenoid valve and the welding torch, from the third solenoid valve to the welding torch. A switching mechanism for shielding gas in arc welding, consisting of a second check valve that only allows the flow of compressed air.