JPS6028584B2 - Weaving welding method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to an improved weaving process using non-consumable electrode welding.

Generally, the weaving welding method is often used for automatic welding of fixed pipes in all positions.

When a circumferential joint is formed by automatic welding in all positions by bringing together the ends of a pair of pipes 3 having joints, as shown in Fig. 1,
The welding torch 1 is rotated in the direction of the arrow, and the filler metal 2 is supplied from the advancing direction side. In this type of welding, first, after initial layer welding as shown in FIG. 2, overlay welding is performed as shown in FIG. 3 to fill in the joint portion. Above all, overlay welding is the part that affects welding efficiency. Therefore, a method has been adopted in which the welding torch is mechanically moved within the groove in a direction perpendicular to the direction of rotation of the welding torch to increase the deposited metal for one layer of overlay welding. This method is called the weaving method, and a diagram of its principle is shown in FIG. 4 is a groove, 5 is an electrode of a welding torch, and 6 is a cross section of the pipe 3.

On the other hand, in all-position welding, prevention of dripping of weld metal,
In order to achieve complete penetration at both ends of the weaving, it is customary to provide a momentary pause time for the welding torch 5 at both ends of the weaving, and to make the welding current vary in height in synchronization with the behavior of the weaving. There is. The conventional weaving pattern and welding current have a relationship as shown in FIG.

The horizontal arrow direction is the moving direction of the welding torch 5, and the welding torch 5 moves between the weaving width B corresponding to the width of the joint 4 and stops at both ends 7a and 7b of the cross section 4. The moving time of the welding torch 5 is T, and the stopping time is T2. The weaving pattern of the welding torch 5 is shown in FIG. 4a, and the welding current pattern is shown in FIG. 4b. That is,
Welding is performed at a low current of 1 L during the moving time T of the welding torch 5, and at a high current IH during the period of stop. Furthermore, the behavior of the filler rod 2 is similar to the welding current, when the current is high,
When the current is low, the pattern becomes less coupled. However, recently, the desire to improve welding efficiency is increasing day by day.

As a means of increasing the amount of welded metal per unit time,
In other words, a method is taken to increase the amount of contribution of melting salary. However, in the above-mentioned conventional method, the heat input of the welding current is taken to melt the filler rod, and the welding toe 7a
, 7b could not be completely fused, and a defect appeared. The present invention has been made to eliminate the above-mentioned drawbacks, and it is an object of the present invention to provide an improved weaving welding method in which the high current time is increased and the low current time is shortened in the weaving pattern.

The method of this invention will be explained in detail below based on the drawings.

In FIG. 5, the weaving pattern is the same as that of the conventional method. However, the welding current pattern is different from the conventional method as shown in FIG. 5b. As soon as the welding torch 5 starts to move from one end, the welding current changes to a low current IL.
Therefore, that time is T3 (T,), and the current is high IH before reaching the other end, and the current IH is high even during the time when the welding torch 5 is stopped, and that time is T4 (>T2). It is something. As a result, a high heat input due to the high current IH is applied from before reaching both ends, increasing the heat input effect to the toe, resulting in a defect-free fused part.
In particular, the second layer of overlay welding has been described in detail, but the above effects can be obtained in any layer. moreover,
Actual pipe welding is complicated, and arc blow phenomena are often observed. This phenomenon also greatly affects the fusion of the toe.
In this case, the above welding conditions may be used at either the left or right weaving end facing the arc blow side. It should be noted that it is more advantageous from the viewpoint of heat input effect to supply the melt in a pattern based on the follow-up method. As described above, the method of the present invention has the effect of increasing the amount of deposited metal while eliminating defects, particularly at the toe, and significantly improving welding efficiency.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the principle of all-position welding, Figure 2 is a diagram showing the first layer welding at the weld groove, Figure 3 is a diagram to explain weaving welding, and Figure 4 is a diagram showing weaving by the conventional method. FIG. 5 is a pattern diagram showing the relationship between weaving and current according to the present invention. 1... Welding torch, 2... Filler rod, 3... Pipe, 4
... Groove, 5... Electrode, 6... Material to be welded, 7a
, 7b... stop weaving part. In the drawings, the same or corresponding parts are denoted by the same reference numerals.
Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] 1 In the weaving welding method in which build-up welding is performed while weaving a non-consumable electrode type welding torch, a process in which the welding torch starts moving from one end and welds with a low current; A weaving welding method comprising the step of performing welding at a high current from a predetermined time before reaching the end of the frame and during a stop period at the other end.