JPS61206564A - Three o'clock welding of steel material - Google Patents

Abstract

PURPOSE:To disuse a back chipping work and to weld stably without the need of specially big capacity power source by specifying the electrode gap, welding current difference and welding voltage difference in case of welding by arranging in opposition electrodes on both front and back faces of a welding point. CONSTITUTION:The power source characteristics, polarity and wire diameter of the preceding electrodes 2, 3 of the front and back respectively are made the same in the initial layer welding of multiple electrodes both faces simultaneous three o'clock welding method to perform back chipping by opposing the electrodes from the front and back faces. The gap of electrodes in the progressing direction of the front and back preceding electrodes each other is taken as 0-50mm as well. Further the welding is performed with the difference in the welding current between the preceding electrodes each other being within 10% and the difference in welding voltage being within 2%.

Description

Detailed Description of the Invention (Industrial Field of Application) This invention is applied to horizontal butt joints that require complete penetration, in which multiple electrodes are placed facing each other on both sides of the welded part to simultaneously weld both sides of the steel material. This relates to a simultaneous lateral welding method.

(Prior art) In horizontal welding that requires complete penetration, as shown in Fig. 4, conventional welding is carried out on one side of the weld, and the back welding is performed on the opposite side of the weld, indicated by diagonal lines. A method is known in which the root portion (Atjl) is removed by welding the root portion and then welding the root portion. However, implementation of this back hole increases the welding material cost, work cost, and period cost, so it has been required to eliminate the back hole. Therefore, in order to realize simultaneous horizontal welding on both sides, a method is proposed in which a gap is provided in the groove root part A as shown in Fig. 5 to enable back wave welding and ensure penetration of the root part. As shown in Japanese Patent No. 139468, after welding from one side, the welding from the other side is sufficiently large, and the bath metal 11 of the m-joint on one side is still at a high temperature after solidification so that stable lapping can be performed. A method has been adopted in which the weld metal 12 is bath-welded from the opposite side during the process (see FIG. 6).

However, when performing uranaba bathing with a gap provided between the groove root sections, it 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, the welding in root part A will drop, and if the root spacing is too small, uranami welding will be impossible.
For this reason, sufficient penetration cannot be obtained when welding from the opposite side.

Furthermore, it is extremely difficult to maintain this root spacing within an appropriate range for large structures.

On the other hand, in a method in which welding is performed from the opposite side while the weld metal on one side is still hot after solidification so that the penetration from the opposite side is large enough to enable stable lapping, there is a method to prevent fluctuations in root spacing. Sensitive, root spacing must be kept within a certain range. In addition, in this method, it is necessary to control the shape of the bath in order to ensure complete penetration of the root part A, which requires equipment for precise groove tracing. It has drawbacks such as high equipment costs. Furthermore, 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 chiseling work to ensure root spacing accuracy, reduce equipment costs for precise groove tracing, and provide a sufficiently large penetration depth. The purpose of this project is to provide an inexpensive and stable horizontal welding method for steel materials that does not require a special large-capacity power source to ensure this.

(Means for Solving the Problems) The present invention provides a power source for the front and rear leading electrodes in the first layer welding of the multi-electrode double-sided simultaneous horizontal welding method in which electrodes are arranged opposite to each other on both the front and back sides of a weld joint. The characteristics, polarity, and wire diameter should be the same, the distance between the leading electrodes in the direction of movement should be 0 to 50 m, and the welding current difference between the leading electrodes should be within 10 inches, and the welding voltage difference should be within 2 inches. The gist of this paper is a horizontal welding method for steel materials, which is characterized by the following.

The details of the configuration of the present invention will be explained with reference to FIGS. 1(a) and 1(b). In the figure, 1 and 1' are base materials in the horizontal butt joint, 2 is the leading electrode on the front side, 3 is the leading electrode on the back side, 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). The welding wire 6 is supplied with electric power from a welding power source, and shear arc welding is performed by an arc generated between the base material 1.11 and the wire.

Shielding the welding area from the atmosphere can be done by using a shielding gas or a flux. (Function of the invention) Conventionally, when welding horizontally with multiple electrodes facing each other on both the front and back sides, welding progresses first at the initial welding part. When the distance between the front and back electrodes in the direction of movement is short, if the distance between the front side leading electrode 2 and the back side leading electrode 3 is 0 to 50 cm in Figure 1, each of the electrodes 2 and 3 The metal welded by the electrode comes into contact in a molten or semi-molten state. For this reason, the front side leading electrode 2
Due to the difference in arc force generated between the front electrode 3 and the back side leading electrode 3, the molten weld metal is blown off to one side of the groove, as shown in FIG. 3, and both sides cannot be finished at the same time.

For this reason, it has not been possible to commercialize welding where the distance between the front side leading electrode 2 and the back side leading electrode 30 is 0 to 50 cm.

Now, as a condition for stably forming weld metal at the center of the groove, it is sufficient to make the arc force during welding of the front side leading electrode and the back side leading electrode almost the same. The arc force and arc pressure distribution in arc welding will be the same if the wire diameter, protrusion length, shielding gas, or flux are constant, and if the current and voltage are constant.

In order to balance the arc force in this way and stably form weld metal at the center of the groove, the welding power sources for the front side leading electrode 2 and the back side leading electrode 3 need to be in phase.

The range of conditions for forming weld metal at the center of the groove is that a difference of within 10% in welding current and within 2 inches in welding voltage can be tolerated between the leading electrode on the front side and the leading electrode on the back side, as shown in Figure 2 (,). The bead shape shown can be obtained.

In addition, the required current to ensure penetration of the root part at this time is 3508 or more due to the arc interference effect of the front side leading electrode and the back side leading electrode at the 45° mold groove. There is no need for high tracing, and welding can be performed at a root spacing of 0 to 3 m.

According to the present invention, the current can be lowered compared to the conventional method, which requires about 450 A, and there is an advantage that the cost of the welding power source can be reduced by using a general-purpose power source.

The penetration of the initial layer by the front and back electrodes is shown in Figure 2 (&
) As shown in Figure 2, the shape is prone to hot cracking, so by forming weld beads using trailing electrodes on the front and back sides, as shown in Figure 2 (6), the direction of solidification is changed and hot cracking is prevented. do. This trailing electrode does not need to be a one-sided electrode, and may be more than one electrode. It goes without saying that this trailing electrode will greatly improve welding efficiency.

(Example) A steel material with a thickness of 19mm (8M
Lateral butt welding of 50C) was carried out on the test case shown in Table 1, and as shown schematically in Figure 7, sufficient penetration and i
- It was possible to obtain a curved shape.

Table 1 (Effects of the Invention) As described above, according to the present invention, there is no need for special operations such as gap adjustment to ensure root spacing accuracy before welding and chiseling after welding, and it is possible to form a precise groove profile. Since there is no need for equipment costs for this process or a special large-capacity power source to ensure a sufficiently large penetration, it is possible to perform horizontal welding at low cost and stability, resulting in extremely excellent effects such as large economic effects. has.

[Brief explanation of the drawing]

FIG. 1(a) is a top view showing an outline of a welding apparatus for carrying out the present invention, FIG. An explanatory diagram showing a weld bead, Fig. 2(b) is an explanatory diagram showing a weld bead obtained when the front side and back side trailing electrodes are further stacked on top of (a), and Fig. 3 is an explanatory diagram showing the weld bead obtained. A diagram showing a defective bead that occurs when a large difference in arc force occurs between the front leading electrode and the back leading electrode in the device shown in Figure 1. Figure 4 shows the welding procedure of the conventional horizontal welding method in which welding is performed only from one side. Fig. 5 is an explanatory diagram showing the main points of the conventional horizontal welding method, Fig. 6 is an explanatory diagram showing the main points of the conventional horizontal welding method, and Fig. 7 is an explanatory diagram showing the main points of the conventional horizontal welding method. FIG. 2 is a schematic diagram showing a packed state (the shaded area is the first layer). Figure 1 (α) (b) Figure 31 Figure 4 Figure 5 Figure 6

Claims (1)

[Claims] In the first layer welding of the multi-electrode double-sided simultaneous horizontal welding method, in which welding is performed by placing electrodes facing each other on both the front and back surfaces of the weld joint,
The power supply characteristics, polarity, and wire diameter of the leading electrodes on the back side are the same, the electrode interval in the direction of movement between the front and back leading electrodes is 0 to 50 mm, and the welding current difference between the leading electrodes is within 10%. A horizontal welding method for steel materials, characterized by welding with a voltage difference within 2%.