JPH0122068B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for cooling materials to be welded during welding.

Welding is used to join pipes together. In this case, the straight pipes are welded together as shown in FIG. The straight pipes 1 are butted against each other and the straight pipes 1 are rotated around the axis of the straight pipes 1. Then, the welding torch 2 is installed downward from above to weld the groove 3 provided around the entire circumference of the straight pipe 1. In this type of welding, the straight pipe 1 rotates, so if the material requires cooling, you can spray water from below toward the straight pipe 1 with the nozzle 4 as shown in the figure, and the straight pipe 1 itself will rotate. The entire circumference of the tube 1 will be cooled.

On the other hand, if the pipe is curved and it is difficult to weld while rotating the curved pipe, so-called all-position welding is performed in which the curved pipe is fixed and the welding torch is rotated around the curved pipe. It will be done.

A front view and a side view of a conventional welding device for all-position welding are shown in FIGS. 2 and 3, respectively. By turning the head clamp handle 6, the welding head 7 is rotatably attached to the bent pipe 8. An arc is ejected from the welding torch 9 toward the bent pipe 8, and the wire cable 14' and wire guide tip 1 are moved from the wire reel 10 by the driving force of the wire feeding motor 11.
A welding wire 14 is fed through 3. While welding in this manner, the welding head 7 equipped with the welding torch 9 rotates once around the curved pipe 8 by a drive motor (not shown), thereby completing one pass welding. At this time, the wire cable 14', the power cable 12 for supplying electricity, and the gas cable 15 for supplying inert gas wind around the bent pipe 8 as shown in FIGS. 4 and 5. Therefore, every time one pass of welding is completed, the welding head 7 is rotated in the opposite direction to that during welding while the arc is stopped, and the wire cable 14' is
The power cable 12 and gas cable 15 are released. As described above, all pass welding is completed by repeating forward and reverse rotation of the welding head 7 around the curved pipe 8.

However, in this welding method in which the welding head rotates around the material to be welded, the bent pipe is not cooled, and on the other hand, if water is sprayed from a fixed direction as in the case of straight pipe welding, the welding head itself will be damaged. As the welding head rotates, water splashes onto the welding head, which is inconvenient. Therefore, in the case of all-position welding, the welding heat is accumulated in the welded material each time welding passes are repeated, and the temperature of the welded part increases. Therefore, welding defects such as weld cracking due to this temperature rise, deterioration of corrosion resistance due to carbide precipitation, and oxidation occur, leading to a decline in quality.

SUMMARY OF THE INVENTION Accordingly, the present invention provides a method for cooling materials to be welded, which eliminates these drawbacks and enables high-quality welding. The configuration of the present invention that achieves such an object is such that in a welding method in which welding is performed by rotating a welding torch around the workpiece, the welding torch is always positioned approximately opposite to the workpiece after the compressed gas has been cooled once. It is characterized by cooling the material to be welded by spraying it from the side toward the material to be welded.

Hereinafter, the present invention will be explained in detail based on an embodiment shown in the drawings.

The method for cooling a material to be welded according to the present invention is used when welding is performed by rotating a welding torch around the material to be welded. Shown is the equipment installed to carry out the process. Note that parts that are the same as those of the conventional welding device are given the same numbers, and only the differences will be explained.

As shown in FIGS. 6, 7, and 8, a nozzle 16 is provided on a side substantially opposite to the welding torch 9 with respect to the bent pipe 8 as the material to be welded. The nozzle 16 is connected to a vortex tube 17 via a connecting pipe 22, and the vortex tube 17 is further connected from a supply port 21 to an air compressor (not shown) via a pipe 24. These nozzles 16 and vortex tubes 17 are attached to the welding head 7. Therefore, the welding torch 9, nozzle 16, and vortex tube 17 rotate together with the welding head 7 around the bent pipe 8, and the nozzle 1
6 is located on the substantially opposite side of the welding torch 9 to the bent pipe 8.

As is well known, the vortex tube 17 has a structure as shown in FIG. In the figure,
An orifice 19 is provided in the upper part of the cylindrical main body 18, and a flow ratio control valve 20 is provided in the lower part. From the supply port 21 connected to the air compressor to the main body 18
When compressed air is blown in the tangential direction of the inner circumference, an ultra-high-speed rotating vortex is created inside the main body 18 as shown by the arrow (200,000 to 300,000 revolutions per minute). A large pressure difference is created between the center and the outer periphery of this vortex, and air moves toward the center, causing its temperature to drop due to expansion. The cold air generated in this center is the orifice 19
The air at the outer periphery is discharged to the outside through the donut-shaped gap of the flow ratio control valve 20.

The nozzle 16 is shown in FIG. The nozzle 16
is a housing whose surface facing the curved pipe 8 forms a concave radius, and is connected to the vortex tube 17 through a connecting pipe 22. A large number of jet ports 23 are provided on the surface facing the curved pipe 8, and cooling air is jetted from the jet ports 23.

Although compressed air is used as the compressed gas in this embodiment, it is not limited to air. A vortex tube is used to cool the gas, but various other cooling methods are possible. Further, in this embodiment, the nozzle is attached to the welding head and rotates together with the welding head, but the nozzle may be rotated by a separate driving means.

Welding is performed as follows using this method of cooling the materials to be welded. Compressed air supplied from the air compressor enters the vortex tube 17 through the supply port 21, and warm air enters the vortex tube 17 through the flow ratio control valve 2.
Only the cooling air discharged to the outside from the connecting pipe 22
It enters the nozzle 16 through. and spout 3
This cooling air is blown out from 3 toward the bent pipe 8. In this case, the welding torch 9 is connected to the bent pipe 8.
Since cooling air is always blown out from the substantially opposite side, the bent pipe 8 can be cooled without interfering with welding.

As described above with reference to the drawings, the present invention has the following effects. Since cooling gas is sprayed onto the welded area, temperature rise can be prevented, preventing welding defects and improving quality. Furthermore, it is possible to weld materials that were previously impossible to weld due to the inability to cool them. Cooling gas can be blown onto the welded material not only during welding but also during non-welding, resulting in a large cooling effect. Since cooling is performed using gas, it is extremely easy to handle and does not require treatment after use, unlike cooling using liquid. By attaching a nozzle that spouts gas to the welding head, the drive motor for rotating the welding head can also be used to rotate the nozzle.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram showing a cooling method for straight pipe welding, Figures 2 to 5 relate to a welding device for curved pipes, Figure 2 is a front view, Figure 3 is a side view, and Figure 4 is a diagram showing a cooling method for straight pipe welding. 5 is a front view for explaining the action, FIG. 5 is a side view for explaining the action, and FIGS. 6 to 10 relate to a welding device for carrying out the method for cooling materials to be welded according to the present invention, 6 is a front view, FIG. 7 is a side view, FIG. 8 is a plan view, FIG. 9 is an explanatory view of the vortex tube, and FIG. 10 is an explanatory view of the nozzle. In the drawing, 6 is a head clamp handle, 7 is a welding head, 8 is a bent pipe, 9 is a welding torch, 10 is a wire reel, 11 is a wire feeding motor, 12 is a power cable, 13 is a wire guide tip, 14
14' is a welding wire, 14' is a wire cable, 15 is a gas cable, 16 is a nozzle, 17 is a vortex tube, 18 is a main body, 19 is an orifice, 2
0 is a flow ratio control valve, 21 is a supply port, 22 is a connecting pipe, 23 is a spout, and 24 is a pipe.

Claims (1)

[Claims] 1. In a welding method in which welding is performed by rotating a welding torch around the welding material, compressed gas is once cooled and then always injected toward the welding material from approximately the opposite side of the welding torch. 1. A method for cooling a welded material, the method comprising: cooling the welded material by cooling the welded material.