JPS6016306B2 - Arc welding method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an arc welding method for efficiently and high-quality welding of thick plates in a single-type joint state.

Conventionally, when performing arc welding of a type 1 groove on a thick plate with a thickness of 10 to 2, in order to ensure fusion at the bottom, the first
As shown in the figure, the MIG wire/electrode 6 of the MIG (skin G) welding torch 5 is perpendicular to the base material 1 to be welded, and the groove gap G
The arc 8 is ignited in this state. The migwayer/electrode 6 is melted and fused with the base material 1 to be welded.

In this state, the welding bead 2 is formed by moving the migwire/electrode 6 along the groove gap and performing one pass welding. Figure 2 is a cross-sectional view of Figure 1, where 1 is the base material to be welded;
2 is a one-pass MIG welding beat on one side. FIG. 3 shows another conventional embodiment in which the wire and electrode 6 of the welding torch 5 is oriented at right angles to the extending direction of the welding point and at an inclination angle of 500 to 60 degrees with respect to the surface of the base material 1 to be welded. arc 8 is generated at a location somewhat below the surface.

The migwire/electrode 6 is melted and fused with the base material 1 to be welded. In this state, by moving the MIG wire/electrode 6 along the groove gap and welding in one pass, the MIG front side welding bead 3 is obtained as shown in the cross section of Fig. 4, and the back side is also welded in one pass in the same manner as above. By doing this, the MIG back side welding bead 4 shown in FIG. 4 above is obtained. However, in the single-side one-pass method as shown in FIG. As a result, the grooved packing plate 7 is significantly damaged, and components of the packing plate (mainly copper) are mixed into the welded area, resulting in weld cracking.

Furthermore, since it is one-sided welded, the welding speed is slow, and even when takt time is limited, there is a major drawback in that it cannot meet the demands. In addition, in the case of double-sided MIG welding as shown in Figure 3, not only the torch angle but also the error in the aiming position of the electrode tip greatly affects the weld bead shape, and even a small error can cause an arc to occur at the top or near the bottom. The shape of the weld bead is not consistent due to arc generation. If the arc occurs at the top, the weld metal will not fuse to the inside, resulting in a bead with insufficient penetration, whereas if the arc occurs near the bottom, the weld metal will not fuse to the inside, resulting in a concave bead with sufficient penetration but a concave surface. Become. Figures 5 and 6 show the state of insufficient penetration and concave beats. Furthermore, in welding where the takt time is limited, the welding speed is quite high, so the welding current needs to be very high, which causes the molten metal to drip, promoting concave bead formation, and causing continuation. It is difficult to maintain the penetration depth at around 60% of the plate thickness and to obtain convex beats with good reproducibility.Furthermore, in the double-sided single-layer welding shown in Figure 3, welding on the front side and back side is a separate process. When targeting automated welding equipment in line, the welding time required for one side is shorter than one-pass welding on one side, so if takt time is limited, it is not more advantageous than one-pass welding on one side. However, there were problems with reproducibility.

As described above, although the conventional methods have certain advantages, they have fatal drawbacks.

The present invention was made to eliminate these drawbacks, and provides an arc welding method with good reproducibility and a smooth welded area.

Hereinafter, FIG. 7 showing an embodiment of the present invention will be described.

In Fig. 7, the wire/electrode 6 of the MIG welding torch 5 is
A direction perpendicular to the direction in which the shaped groove extends, that is, a direction perpendicular to the direction of movement of the MIG welding torch 5, and set at an oblique angle of 60o to 80o with respect to the surface of the base material 1 to be welded, The wire/electrode 6 is aimed at a slightly lower position and reciprocating welding is performed. In Figure 7, 1, 5, 6'
8 shows the same thing as in FIG. 3, and 9 is a packing plate without grooves. During outward welding, the arc 8 is generated at the lower part of the weld joint, so that the weld metal 12 is completely exposed to the bottom as shown in FIG. In return welding, the top of the welded part during outward welding is re-welded, so that a welded part 13 with excess welding is obtained as shown in FIG. 10. Since the grooveless packing plate 9 is used, the weld metal exposed at the bottom is almost smooth. As shown in FIG. 8, the back side of the weld is tanned by TIG welding to obtain a smooth weld bead 14 as shown in FIG. 11.

In this case, it is necessary to use a packing plate 7 with grooves.

In FIG. 8, 10 is a TIG welding torch, 11 is a tungsten electrode, and 7 is a grooved packing plate. As mentioned above, in the conventional MIG double-sided single-layer welding method shown in Figures 3 to 6, it is necessary to control the penetration depth to around 60%, and it is necessary to control the penetration depth to around 60%, so that the electrode aim position, current, butt gap, etc. In contrast, according to the present invention, there is no need to control the penetration depth, and it is only necessary to ensure that the weld metal is exposed at the bottom, so the aim of the electrode can be adjusted. There is considerable margin in terms of accuracy, current conditions, and butt gap, and the reproducibility of welding quality is good.

For this reason, it is possible to weld with a very large current in MIG front side welding, and as a result, it is possible to weld at approximately twice the welding speed. This is equivalent to the case of single-layer welding. Moreover, in the case of automatic welding, it is possible to use the return time of the equipment and jig for return welding, so even if the welding time is slightly longer, the overall time required per welding piece is the same. It is possible to Do not use filler wire for TIG welding on the diamond side either.

Because it is tanned welding, the welding speed is equivalent to MIG welding. Furthermore, the welding torch angle should be increased from 60o to 800o.
Therefore, the arc generation point does not occur on the packing plate 7b, but is generated reliably in the base material within the joint, so that the packing plate is not damaged.

Also, since the back side is TIG tanned and welded, the welded part is very smooth and there is no spatter attached like with MIG welding.
There is no need for post-grinding or replacement work, and the product value is greatly improved.

Next, an example of welding conditions for a European steel plate with a thickness of 14 ribs will be shown.

For front welding, the current is 42 mm and the welding speed is 80 m/min, and for hair side welding, the current is 35 m, 300-40 m/min. In the above, MIG welding was used to weld the front side of the type 1 joint of the base material to be welded, but carbon dioxide gas semi-automatic welding may also be used.

As described above, according to the present invention, after performing reciprocating welding on the front side of type 1 joint with the welding torch set at an angle of 600 to 800, the back side is tanned and welded, so the welded part becomes smooth and the This eliminates the need for grinding and post-finishing, and improves the reproducibility of welding quality.

[Brief explanation of the drawing]

Figures 1 and 3 are perspective views showing conventional arc welding, Figures 2 and 4 are sectional views of welds in conventional single-layer MIG welding on one side and both sides, and Figures 5 and 6 are single-layer welding on both sides. A sectional view showing an example of insufficient penetration and concave beats in MIG welding, FIGS. 7 and 8 are perspective views and front views showing an embodiment of the present invention, and FIGS. 9 and 10 are front views of the present invention. FIG. 11 is a cross-sectional view of a welded portion in forward and backward welding, and FIG. 11 is a cross-sectional view of a welded portion in which the back side is tanned and welded after the front side reciprocating welding of the present invention is completed. In the figure, 1 is the base material to be welded, 5 is the MIG welding torch, and 6 is the welding torch.
8 is a filler wire/electrode, 8 is an arc, 9 is a packing plate without grooves, and 10 is an FIG welding torch. Note that the same reference numerals in the figures indicate the same or corresponding parts. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 0 Figure 11

Claims (1)

[Scope of Claims] 1. The consumable electrode of the welding torch is placed in a direction perpendicular to the extending direction of the I-shaped groove of the base material to be welded, and at an angle of 60° to 80° with respect to the surface of the base material to be welded. The I-shaped groove is inserted into the I-shaped groove at an inclination angle of An arc welding method characterized by tanning and welding the back side of an I-shaped groove. 2. The arc welding method according to claim 1, which is tanning welding by TIG welding without supplying filler wire. 3. The arc welding method according to claim 1, which is tanning welding by plasma welding.