JPS61206563A - Horizontal welding method for steel materials - Google Patents

Abstract

PURPOSE:To disuse the adjustment of a gap and back chipping and to perform the three o'clock welding of lower cost having stability by specifying the gap in the progressing direction of the preceding electrode each other of the front and back of a welding joint part respectively and the gap between the preceding electrode and succeeding electrode. CONSTITUTION:The gap in the progressing direction of the preceding electrodes 2, 3 each other of the front and back respectively is taken as 30-80mm, the inside of the groove is subjected to a seal weld by the tip-most electrode and the groove center part is melted by the preceding electrode on the opposite side in order to stably forming a welding metal at the groove center part. The distance between the preceding electrode and succeeding electrode is taken as 50-150mm by the succeeding electrodes 4, 5 provided respectively on the front side and back side in order to prevent a high temp. crack by changing the solidifying direction.

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention is a horizontal butt joint of steel materials that requires complete penetration, in which welding is performed simultaneously by facing the upper electrodes on both the front and back sides of the welding part. This relates to a double-sided simultaneous horizontal welding method.

(Conventional technology) In horizontal welding of steel materials that require complete penetration,
Conventionally, as shown in Fig. 4, after welding one side of the welded joint, welded the part shown in diagonal lines on the other side, removed the unwelded root part A, and then welded that part. A common method is to implement However, this back chiseling increases welding material costs, work costs, and period costs'f:
There was a demand for the elimination of the backing, as there was no hope of improving efficiency by simultaneously constructing both sides.

For this purpose, there is a method of providing a gap at the groove root part AK in the rounding to realize simultaneous horizontal welding on both sides as shown in Fig. 5 to enable Uranami welding and ensure penetration of the root part A, or as shown in Fig. 6. After welding from one side, weld metal 12 is welded from the opposite side while the weld metal U in the weld on one side is still at a high temperature after it has solidified so that the penetration from the other side is large enough to enable stable lapping. Method (Japanese Unexamined Patent Publication No. 57-13946
Publication No. 8) etc. have been adopted.

However, when performing Uranami welding with a gap provided in the groove root portion A, the welding is very sensitive to variations in the root spacing, and it is necessary to maintain the root spacing within a certain range. In other words, if the root spacing is too large, welding in the root portion A will drop, and if the root spacing is too small, it will be impossible to carry out Uranami welding, and therefore sufficient penetration will not be obtained when welding from the opposite side. Furthermore, it is extremely difficult to maintain this root spacing within an appropriate range for large steel structures.

On the other hand, the penetration from the opposite side is large enough to allow stable lapping. Even in a method in which welding is performed from the opposite side while the weld metal on one side is still hot after solidification, it is difficult to prevent fluctuations in the root spacing. Be sensitive.

Route spacing must be kept within a certain range. In addition, in this method, in order to ensure complete penetration of the root part, it is necessary to control the shape of the penetration completely, which requires equipment for precise groove tracing. Therefore, it has drawbacks such as high equipment costs. moreover,
This welding method requires a large current to ensure a sufficiently large penetration, requires a welding power source with a large current capacity, and has problems such as increased equipment costs.

(Problems to be Solved by the Invention) The purpose of the present invention is to eliminate the need for special operations such as adjusting the gap to ensure the precision of the route spacing before welding and chiseling the back side after welding, and to form a precise groove. Equipment costs for tracing and special dog capacity to ensure a sufficiently large penetration
The present invention aims to provide an inexpensive and stable horizontal welding method for steel materials that does not require a fi power source.

(Failure to solve the problem) The gist of the present invention is as follows.

(1) In the first layer welding of the multi-electrode double-sided simultaneous horizontal welding method, in which electrodes are arranged facing each other on both the front and back sides of the weld joint, the distance between the leading electrodes on each of the front and back sides in the direction of movement is 30 to 80. 1. A horizontal welding method for steel materials characterized by welding with a distance f of 50 to 150 m between the leading electrode and the trailing electrode on each of the front and back sides.

(2) In 1) above, welding is performed by setting the welding current of the electrode located furthest forward in the direction of movement among the leading electrodes on the front and back sides to be the same as or lower than the welding current of the leading electrode on the opposite side. horizontal welding method.

The details of the configuration of the present invention will be explained with reference to FIG.

1, r indicates the base material in the lateral butt joint. 2
is the leading electrode on the front side, and 3 is the leading electrode on the back side. Also 4
5 is a trailing electrode on the front side, and 5 is a trailing electrode on the back side. A staining force is supplied to each of these electrodes by a welding power source (not shown here). The welding wire is arc welded by the arc generated between the base metal and the wire when a staining force is supplied from the welding power source.

A shielding gas or flux may be used to shield the welding area from the atmosphere.

(Function of the invention) Conventionally, when performing horizontal welding with electrodes facing each other from both the front and back surfaces, if the distance between the front and back electrodes in the advancing direction is short in the initial layer, the welding in the mating section shown in FIG. When the distance between the front side leading electrode 2 and the back side leading electrode 3 is θ~30 dew, the weld metals from each of the six electrodes, electrode 2 and electrode 3, come into contact in a molten or semi-molten state.
As shown in FIG. 3, the molten weld metal is blown away to one side of the groove (due to the difference in arc force generated between the front electrode and the back side leading electrode 3), and both sides cannot be finished at the same time.

Now, as a condition for stably forming weld metal at the center of the groove, the distance between the leading electrodes on each of the front and back sides in the direction of movement is 30 to 80. As m, seal weld the inside of the groove with the most advanced electrode, and melt the center part of the groove with the leading electrode on the opposite side. At this time, if it is less than 30 degrees, the opposite side will be in a molten state, so the melt will drop off at the end, and if it exceeds 80 degrees, the preheating effect will be low and the root part will be difficult to melt. At this time, the current value of the most advanced electrode is set to be the same as or lower than the current value of the preceding electrode on the opposite side, thereby preventing the most recent electrode from blowing through to the back surface. In addition, the required current to ensure penetration of the root section at this time is 3.5 mm each due to the preheating effect of the cutting edge electrode at the 45" mold groove.
It requires less than 50A, which allows the current to be lower than the conventional method, which requires about 450A, and has the advantage of reducing the cost of the welding power source by using a general-purpose power source.6. There is no need for particularly precise tracing, and welding can be performed at root spacings of 0 to 3 m. Penetration of the initial layer by only the leading electrodes on the front and back sides creates a shape that is prone to high-temperature cracking as shown in Figure 2 (Hata). By forming a weld bead on the trailing electrode, the direction of solidification is changed and hot cracking is prevented. For this purpose, it is best to set the distance between the leading electrode and the next trailing electrode to 50 to 150 m (if it is shorter than -50 m, the leading bead may be melted or semi-molten;
On the contrary, 150
If (2) is exceeded, cracks will occur before a bead is formed by the trailing electrode. The trailing electrodes do not need to be one electrode on each of the front and back sides, and may be more than one electrode. It goes without saying that this trailing electrode can improve welding efficiency.

At this time, controllability is better if the power supply characteristics, wire diameter, and polarity of the front, back, leading electrodes, and trailing electrodes are made the same.

(Example) A hot blast furnace body (5M50C material, plate thickness 32 days) of blast furnace equipment was horizontally welded according to the present invention. Table 1 shows the conditions for welding the first layer at that time. FIG. 7 schematically shows the penetration state of the welded part obtained by performing finish welding after the first layer welding. Excellent results were obtained in terms of penetration of the deposited metal in the weld zone, bead shape, and work efficiency, far exceeding those of conventional horizontal welding methods.

Table 1 Leading-to-trailing electrode spacing: 100 spacing between leading electrodes in the advancing direction = 50 ■ (Effects of the invention) As described above, according to the present invention, the distance between the leading electrodes and the trailing electrodes before welding is The back side after adjustment and welding does not require special work such as combs, and is inexpensive and stable as it does not require equipment costs for precise bevel tracing or a special large-capacity power supply to ensure sufficient penetration. Since horizontal welding of certain steel materials can be carried out, the industrial advantage is extremely large.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an outline of a welding apparatus for carrying out the present invention, FIG. 2(a) is a diagram showing a weld bead obtained by the front side and back side leading electrodes according to the present invention, and FIG. (,)
Figure 3 shows the weld bead obtained when the weld bead is further stacked on the front side and back side trailing electrodes.
The figure shows a defective bead that occurs when there is a large difference in arc force between the front side leading electrode and the back side leading electrode in the device shown in Figure 1. Figure 4 shows welding using the conventional horizontal welding method in which welding is performed only from one side. Fig. 5 is an explanatory drawing showing the main points of the conventional horizontal welding method, Fig. 6 is an explanatory drawing showing the main points of the conventional horizontal welding method, and Fig. 7 is an explanatory drawing showing the main points of the conventional horizontal welding method. FIG. 2 is a schematic diagram showing the state of penetration of a horizontal weld (the shaded area indicates the initial layer). Figure 1 (&) (b) Figure 3 Figure 4 Figure 5 Figure 6

Claims (2)

[Claims] (1) In the first layer welding of the multi-electrode double-sided simultaneous horizontal welding method, in which electrodes are arranged facing each other on both the front and back sides of a welded joint, the spacing in the advancing direction between the leading electrodes on each of the front and back sides should be 30 to 80 mm. A lateral welding method for steel materials, characterized in that the welding is performed with the distance between the leading electrode and the following trailing electrode on each of the front and back sides being 50 to 150 mm. (2) Welding is performed by setting the welding current of the electrode located furthest forward in the direction of movement among the leading electrodes on the front and back sides to be the same as or lower than the welding current of the leading electrode on the opposing surface. Lateral welding method for steel materials according to claim 1