JPH0671653B2 - Double-sided simultaneous welding method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a double-sided simultaneous welding method for simultaneously welding from both front and back sides of a plate material and a pipe material.

2. Description of the Related Art Conventional welding of plate materials and pipe materials has generally been performed on the front and back separately.

Problems to be Solved by the Invention Although conventional welding methods, especially TIG welding, are of high quality, there are drawbacks that humping occurs when the welding speed is increased and the penetration depth is shallow. Although there is a switching arc welding method or the like to solve this problem, the price of the welding machine is high and it has not been put to practical use.

Means and Actions for Solving Problems The present invention has been made in view of the above, and a plate material,
In the simultaneous double-sided welding method in which the pipe material is welded from both front and back sides simultaneously, the downward CO ₂ welding or TIG welding electrode is arranged as the leading electrode, the upward TIG welding electrode is arranged as the trailing electrode, and the material to be welded by the leading electrode is arranged. The trailing electrode is arranged at the temperature peak position in the inside to perform welding, and the back side welding is performed by the trailing electrode at the portion welded by the leading electrode and at the temperature peak position by the leading electrode.

Embodiment An embodiment of the present invention will be described with reference to the drawings.

In the figure, reference numeral 1 denotes a pipe to be weld-joined.
Rotate in the direction of the arrow. Reference numerals 2 and 3 denote welding torches which are positioned so as to face each other on the front side and the back side of the welded portion of the pipe 1, and the two tori 2 and 3 are displaced by a predetermined distance 1 in the rotation direction of the pipe 1, that is, the welding direction. There is. The leading welding torch 2 performs CO ₂ welding or TIG welding, and the trailing welding torch 3 performs TIG welding.

FIG. 2 shows the welding temperature distribution by the preceding welding torch 2, and 4a, 4b and 4c in the figure show isotherms. As shown in this figure, the temperature distribution in the plate due to the leading bead has a peak at a position somewhat delayed from the leading welding torch 2, and the trailing welding torch 3 is located at the temperature peak position due to this leading torch.
Face each other. As a result, the preheating effect of the preceding welding torch 2 improves the efficiency of welding by the subsequent welding torch 3.

The actual welding results will be described below.

Figure 3 shows the penetration depth when the preceding welding is performed by TIG welding (300A) and the following welding is performed by TIG welding (150A). The results shown at the left end in the figure are for the case where the inner surface and the outer surface are welded separately, and the other results are for the case where both sides are simultaneously welded by the method of the present invention by changing the leading amount of the torch, and when the inner and outer surfaces are welded separately. On the other hand, in the method of the present invention, the average penetration depth is deep.

Fig. 4 shows the results of CO ₂ welding (350A, 35V) followed by TIG welding (200A).

Usually, in TIG welding, if the welding speed is high, good welding cannot be performed due to a humping phenomenon. Welding current is 20
At 0 A, the humping phenomenon occurs at a welding speed of 250 mm / min or more.

However, according to the method of the present invention, good welding can be performed even at a welding speed of 1000 mm / min or more, and the penetration depth can be dramatically increased.

EFFECTS OF THE INVENTION According to the present invention, the upward trailing electrode is arranged at the temperature peak position in the material to be welded by the downward leading electrode so as to perform welding, so that the preheating effect by the leading electrode is utilized to the maximum extent. The result is a deep penetration depth. Further, according to the present invention, high-speed TIG welding is possible.

[Brief description of drawings]

The drawings show an embodiment of the present invention. FIG. 1 is a diagram showing an embodiment of welding, FIG. 2 is a temperature distribution diagram in a welding plate, and FIG. 3 is a diagram showing a relationship between a penetration amount and a penetration depth of a torch. , 4th
The figure shows the relationship between the welding speed and the penetration depth. 2 and 3 are welding torches.

Claims (1)

[Claims] 1. A double-sided simultaneous welding method in which a plate material and a pipe material are simultaneously welded from both front and back sides, a downward CO ₂ welding or TIG welding electrode is arranged as a leading electrode, and an upward TIG welding is performed.
A double-sided simultaneous welding method characterized in that a welding electrode is arranged as a trailing electrode, and the trailing electrode is arranged at a temperature peak position in the material to be welded by the leading electrode for welding.