JPH01205870A - Welding method for tube panel - Google Patents

Abstract

PURPOSE:To prevent the occurrence of welding distortion and to eliminate stress relief work by welding simultaneously four corner parts of a member to be welded of a tube panel by two downward high-speed rotating torches on the surface side and two upward high-speed rotating torches on the rear side. CONSTITUTION:The two torches 11 and 13, and the two torches 12 and 14 are arranged respectively with respect to a surface side weld zone and a rear side weld zone. The high-speed rotating arc torches are used wholly for the four torches. The high-speed rotating arc torch feeds a welding wire 6 to the center of an electrode nozzle 5 and is made eccentric by an eccentric hole of an electrifying chip 7. The electrode nozzle 5 is rotated at a high speed by a motor and a heat source is dispersed uniformly and the peripheral penetration is increased and the bead surface is curved. The four torches are inclined at a prescribed angle on the horizontal surface and arranged at prescribed intervals in the welding direction from physical restriction. By this method, the occurrence of the welding distortion is prevented and inversion of a work is not necessary and a manufacturing stage can be simplified.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method of welding tube panels.

[Prior Art] Conventionally, a tube panel shown in FIG. 5 has been used in boilers and the like. This is formed by welding the four corners of a plate-shaped connecting member 2 to a tube 1 arranged in parallel. Conventionally, as shown in FIG. 5, first, both front ends of the connecting member 2 are welded to the tube 1 using a downward welding method, and then the connecting member 2 is reversed and both rear ends are welded using a downward welding method. There is.

[Problems to be Solved] However, welding distortion occurs because the tube 1 and the connecting member 2 have different rigidities and different expansion rates due to welding heat. Therefore, after reversing and removing the distortion by welding the front side, weld the back side. and,
In order to remove the distortion caused by back side welding, it is turned over again and in some cases intermediate annealing is performed before the distortion is removed.

As mentioned above, since the conventional welding method involves downward welding, it is necessary to reverse the weld at least once, and it is necessary to reverse the weld one more time to remove distortion. Further, there are problems such as requiring a large number of man-hours to remove distortion.

In this case, in order to reduce the number of man-hours for strain relief, it may be possible to reduce the occurrence of distortion by restraining and welding with a strong restraint jig, but this poses a problem in that the number of man-hours required for setup increases.

The object of the present invention is to provide a tube panel welding method that can solve the above-mentioned problems.

[Means for Solving the Problems] The tube panel welding method of the present invention provides a tube panel welding method in which four corners of a connecting member of a tube panel are formed by connecting a plurality of tubes arranged in parallel via a connecting member. When welding, two downward torches are placed corresponding to the two welds on the front side, and two upward high-speed rotating arc torches are placed corresponding to the two welds on the back side. This method is characterized by simultaneous welding.

[Function] By simultaneously welding the front side and the back side, thermal stress due to welding is generated almost simultaneously and symmetrically, so almost no distortion occurs. In this way, distortion removal becomes unnecessary and inversion can be omitted.

Further, by welding both ends of the back side with a high-speed upward rotating arc torch, it is possible to perform a good fillet weld.

[Example] Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

In this example, the dimensions of the tube 1 are an outer diameter of 63.5 mm and a wall thickness of 4 mm, and the dimensions of the connecting member 2 are 9 mm wide, 19 mm wide, and 6 mm thick. A connecting member 2 is interposed between each of the 13 tubes 1 to form a tube panel with a width of about 177Z and a length of 12 m.

Two torches 11.13 are provided corresponding to the welds on the front side, and two torches 12.14 are provided corresponding to the welds on the back side. In this case, high speed rotating arc torches were used for all four torches. As shown in FIG. 4, in the high-speed rotating arc torch, a welding wire 6 is fed to the center of an electrode nozzle 5, and is offset by an eccentric hole in an energizing tip 7. The electrode nozzles 5 are concentrically rotated at high speed in the same direction by a motor. Due to the high-speed rotation of the arc, the heat source is uniformly distributed around the bead, increasing the penetration of peripheral melt and curving the bead surface. As a result, it is possible to obtain effects such as equal expansion by suppressing drooping beads, prevention of undercuts, smoothing of the bead surface, and improvement of welding speed (increasing the length of the legs).

The four torches are each inclined at an angle of 60° with respect to the horizontal plane, as shown in FIG. The torches are arranged in the welding direction at intervals of approximately 100 mm as shown in FIG. 3 due to physical constraints.

For the wire, FCAW (cored wire) 1.2Il+
i, and carbon dioxide gas was used as the shielding gas. The welding speed was 55 On/min. The current of torches 11.12 was 25OA and the voltage was 27V, and the current of torches 13.14 was lowered by IOA to 240A. The rotational speed of the front side torches 11.13 was set to 30H2 in order to reduce the scattering of spatter, and the rotational speed of the backside torches 12.14 was set to 50Hz. Further, since the connecting member is heated by the torch 11 and the molten steel flows easily, the torch 13 has a receding angle of 7° so that the molten steel can be raised later. On the other hand, in order to suppress the bead from hanging down due to gravity, the torch 14 has an advance angle of 7'' to allow the molten steel to flow forward.

In this way, we were able to perform good fillet welding with a throat thickness of 3 on both the front and back sides. Then, the local welding distortion was reduced to 2m/
It is within 1m and the overall distortion is lower than the conventional 10011.
We were able to reduce it to less than 1/10 of 11.

In this example, the tube 1 and the connecting member 2 are connected in advance by temporary welding only at their tips, and as shown in FIG. 8 while pulling the temporarily attached tube panel using two sets of
The seams are simultaneously welded and the process is repeated to produce tube panels.

In the above embodiment, a high-speed rotating arc torch is also used for the downward torch on the front side, but other appropriate welding methods may be used for downward fillet welding.

Further, in the above embodiment, one torch is provided for each seam, but the torches may be provided in tandem for each seam.

[Effects of the Invention] The tube panel welding method of the present invention is as described above, and by simultaneously welding the front side and the back side, it is possible to prevent the occurrence of welding distortion and eliminate the troublesome work of removing distortion. Furthermore, there is no need for reversal as in the case of conventional one-sided welding, and the manufacturing process can be simplified. Furthermore, by performing upward welding with a high-speed rotating arc torch, it is possible to perform good bead fillet welding on the back side as well.

[Brief explanation of the drawing]

1 to 3 are explanatory diagrams showing the arrangement of torches in one embodiment of the present invention, FIG. 4 is an explanatory diagram of a high-speed rotating arc torch, and FIG. 5 is an explanatory diagram of a tube panel. 1...Tube 2...Connection member 11.13...
・Downward torch 12.14...Upward torch Applicant's representative Patent attorney Takehiko Suzue Figure 1 7゜7゜ Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] When welding the four corners of the connecting member of a tube panel, which is formed by connecting multiple tubes arranged in parallel via connecting members, to the tubes, welded joints were placed corresponding to the two welds on the front side. A tube panel welding method characterized by simultaneous welding with two downward torches and two upward high-speed rotating arc torches arranged corresponding to two welding parts on the back side.