JPS62110873A - Method for performing fillet welding - Google Patents

Abstract

PURPOSE:To prevent the generation of a pit and a blowhole, and to obtain a fillet weld metal having a high quality by heating in advance the succeeding fillet weld area by a combustion electrode which has been placed in a front position of an electrode for fillet welding. CONSTITUTION:In case of an automatic fillet welding such as a submerged arc welding, a gas shielded arc welding, etc., a combustion electrode 1 is placed in a front position of an electrode for fillet welding. The succeeding fillet weld area is heated in advance by heat of the combustion electrode 1, and subsequently, welding is executed by the succeeding welding electrode 2. Within a range of a speed of a regular fillet welding, an interval between the preceding combustion electrode 1 and the fillet welding electrode 2 is set to about 100-200mm. An arc generating position of the combustion electrode 1 is set to a position 3 of the lower plate 6 side being adjacent to a root bottom 7. In this way, a weld metal which is excellent in a paint steel plate especially can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fillet welding method that can be applied to all locations where fillet welding is required for shipbuilding, marine structures, iron structures, mechanical products, etc.

[Conventional technology]

The majority of fillet welding is welding 4 with a vertical plate (lip material) 5 to increase the separation of the lower plate 6, which is the outer shape of the member, as shown in Fig. 5, and the weld leg length is 4 to 4. Most of them are 8 dragons.

For this fillet welding, each company is increasing the speed and automation of welding, and automatic horizontal fillet welding is performed by submerged arc welding or gas shielded arc welding, which changes from one electrode method to multi-electrode 2 to 5 electrodes. ing.

However, steel plates used in shipbuilding, marine structures, and bridges are painted steel plates that have been treated with anti-corrosion coating called shop primer treatment by steel manufacturers to prevent rust. When fillet welding is performed, as shown in Figure 5, the bit 8 on the weld surface and the plow hole 9 inside the weld metal
This occurs frequently, making it impossible to obtain good welding quality.

For this reason, at present, before assembling a fillet joint, it is common to carry out pretreatment by grinding off the paint on the part to be welded using a belt grinder or the like, which is a bottleneck in reducing costs. In addition, even if this paint grinding is carried out, if the period from grinding to assembly and welding is prolonged, bits and blowholes similar to those caused by paint stains may occur due to the adhesion of oil, moisture, sawdust, etc. There were problems such as.

As mentioned above, in the conventional fillet welding method, in order to ensure the quality of the welded part, the paint film is removed by polishing, and even after the polishing is removed, curing is required to prevent the adhesion of oil, fat, moisture, #R], etc. It took a lot of man-hours (increased cost) to do so.

[Problem that the invention seeks to solve]

The cause of bits and blowholes in the conventional fillet welding method is that paint, oil, moisture, etc. adhering to the fillet weld root bottom 7 burn and decompose, as shown in Figure 5.
This is thought to be the result of applying gas pressure as gas or water vapor (H2O) into the weld metal and blowing it out into the molten metal just before solidification.

Therefore, it is thought that bits and blowholes in the subsequent fillet weld metal can be prevented by burning and decomposing these adhered foreign substances to degas them immediately before welding. However, performing this incineration treatment or grinding and removal using a belt grinder separately from the welding process increases the number of man-hours.

Therefore, in the present invention, the process of polishing and removing paint such as shop primer is omitted (welding is done while the paint is still on),
We also investigated an automatic fillet welding method that can prevent the harmful effects of paint, oil, fat, moisture, etc. at the same time as fillet welding, and can produce a healthy fillet weld.

[Means for solving problems]

The present invention provides a fillet welding electrode at the front position in various automatic fillet welding such as submerged welding and gas shielded arc welding.
This fillet welding method is characterized by arranging a combustion electrode, preheating (melting) the subsequent fillet welding area with the heat of the combustion electrode, and then performing welding with the subsequent welding electrode.

The present invention will be explained in detail below with reference to FIGS. 1 and 2.

First, the setting of the distance between the electrodes will be explained with reference to FIG.

In the normal fillet welding speed range of 40 to 150 cm/min, it is best to set the distance between the preceding paint combustion electrode 1 and the fillet welding electrode 2 to 100 to 200 cm. Effective in preventing holes.

Next, the setting of the arc generation position of the electrode for burning paint will be explained with reference to FIG. The arc generation position of the electrode for burning paint, etc. should be on the lower plate 6 side close to the root bottom 7, and the aim is to aim for a position 6 where the weld metal does not block the gap at the root bottom, to prevent bits and blowholes. Particularly effective in prevention.

[Effect]

If the distance between the electrodes is 100 to 200g, the combustion gas can dissipate from the root bottom to the subsequent fillet weld metal, and the preheating effect of the fillet weld can be obtained, resulting in delaying the solidification and cooling of the fillet weld. , bits and blowholes can be prevented, and the appearance of the weld bead can be improved.

〔Example〕

Table 1 shows steel plates coated with zinc-rich primer (
The leg length was 6 gz by using the conventional fillet welding method (applied ■~■) and the fillet welding method of the present invention (applied ■~O).
This is the result of investigating the number of bits and blowholes in fillet weld metal when fillet welding is performed. According to the conventional method, 200 to 300 blowholes are generated per 1 m of welding length, whereas according to the method of the present invention, 50 blowholes/ff are generated.
It can be seen that the blowhole prevention effect is great when it is less than i (it actually decreases to K).

Figure 3 shows 1 steel plate coated with zinc clinch primer.
When welding using the electrode gas-shielded arc welding method, a gas-shielded arc welding electrode for burning paint is placed at each position within a range of 15 to 400n in front of the welding electrode.
As shown in Fig. 4, only the lower plate side is smaller than the subsequent fillet weld leg length 5 cm, and the root bottom is not melted (1
50AX20VX60cb As a result, a remarkable blowhole prevention effect was obtained in the range of inter-electrode distance of 100 to 200n.

When the distance between the electrodes is less than 100 m, the subsequent fillet weld passes before the combustion gas pressure of the paint at the root bottom has sufficiently dissipated, which applies gas pressure to the fillet weld metal and causes a blowhole. It is estimated that this is the cause. Also 2
00. , 500 or more, and 500i + 1, the number of tile blowholes tends to increase, but this is due to the effect of preheating at short distances, which slows down the solidification of the subsequent fillet weld metal and prevents the blowhole from floating. This is thought to be due to the fact that, although it is effective for dispersion, the effect of floating and dissipating the blowhole due to preheating becomes weaker at longer distances.

FIG. 4 shows an investigation of the influence of the arc generation position of the combustion electrode and the bead shape (black-painted crushed portion) of the preceding electrode (combustion electrode) using a steel plate coated with a zinc clinch primer.

■ is the case of the conventional method, ■ and ■ are the cases where an arc is generated on both the upright plate and the lower plate, and combustion is performed under conditions such that the weld metal closes the gap at the bottom of the root. Blowhole prevention effect is small. -1 Method (2) of the present invention is a case in which a small arc is generated only on the lower plate so as not to block the gap at the root bottom, and the effect of preventing blowholes is remarkable.

As described above, the method of the present invention is a high-quality fillet welding method that is obtained by combining the two effects of the distance between electrodes and the starting position and shape of the combustion arc.

〔Effect of the invention〕

Defects in bits and blowholes in fillet welds are
This is caused by combustion gases from paint, oil, moisture, etc. at the root bottom (gap) where the upright board and the bottom board overlap. For this reason, as a result of an experimental study on a method for burning and degassing paint, oil, moisture, etc. from the root bottom prior to fillet welding, we found that, as in the present invention, the distance between the combustion electrode and the welding electrode and the combustion arc We have discovered a method that makes it possible to obtain high-quality fillet weld metal without pits or blowholes without having to grind away paint, etc. (by optimizing the location and shape of the occurrence).

[Brief explanation of drawings]

Fig. 1 is a diagram showing the arrangement of the combustion electrode and welding electrode of the present invention, Fig. 2 is a diagram showing the combustion arc generation position and shape of the present invention, and Fig. 3 is a diagram showing the basis of the setting between the electrodes of the present invention. Graph showing,
FIG. 4 is a chart showing the basis for setting the generation position and shape of the combustion arc of the present invention. FIG. 5 is a diagram showing an example of a defect in conventional fillet welding. Engraving of drawings (no changes in content) Figure 1 Electrode path iII rental

Claims (1)

[Claims] In various types of automatic fillet welding such as submerged welding and gas shielded arc welding, a combustion electrode is placed in front of the fillet welding electrode, and the subsequent fillet welding area is preheated (melted) with the heat of the combustion electrode. A fillet welding method characterized in that welding is then performed using a subsequent welding electrode.