JPH04111975A - Multiple electrode one-side submerged arc welding method - Google Patents

Abstract

PURPOSE:To save labor of condition selection in multiple electrode one-side submerged arch' welding, by giving welding conditions and performing welding after confirming characteristics of beads expected by a data base prepared on a microcomputer in advance. CONSTITUTION:The welding conditions such as the number of welding electrodes, a groove shape and thickness are given and the data base or an empirical formula prepared on the computer in advance is used to calculate the bead penetration width and depth and the quantity of reinforcement of weld which are expected. The welding conditions are determined corresponding to these and welding is performed. Consequently, since the propriety of back bead formation and the excess and deficiency of the quantity of reinforcement of weld can be determined before actual welding, the time, labor and cost for searching the proper welding conditions can be reduced and labor saving is made possible.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for efficiently determining welding conditions for single-sided welding, particularly multi-electrode single-sided submerged door welding used for joining large plates in shipbuilding. It is something.

[Conventional technology]

For jointing large plates in shipbuilding, single-sided Zabumarsito arc welding using two to three electrodes is used as a high-efficiency welding method. However, this welding speed is at most 60 to 70
0m/1Tlln, and there has been little progress in the past 20 years.

On the other hand, recently, from the perspective of marine pollution, there is a trend towards double-structured tankers, and if this is implemented, it will require twice as large plate joining work, creating idle time between the front and rear processes, and reducing work efficiency. It is expected that this will happen. Therefore, in order to flow at the same speed as this large plate joining process, it is necessary to increase the number of factories or to more than double the efficiency of single-sided Zabumarsito arc welding used in the large plate joining process. However, in the former case, it would be enormous not only in terms of securing a factory site but also in terms of funding. On the other hand, in order to increase the speed of welding,
As seen in Publication No. 10570, it is known to increase the number of welding electrodes as a highly efficient welding method for large-diameter steel pipes. However, when increasing the number of electrodes in single-sided welding, the welding conditions must be How to design it is completely unknown territory.

[Problem to be solved by the invention]

The current three-electrode welding conditions are based on various welding factors (welding current,
The results were obtained by conducting experiments using various combinations (voltage, speed, etc.) and evaluating the bead shape one by one. However, in order to implement a new type of single-sided submerged arc welding that exceeds 3 electrodes, a large number of experiments were conducted to address the factors that were even more numerous than when designing the current 3@pole welding conditions, and the bead shape It is necessary to evaluate and design appropriate welding conditions, which is expected to require a great deal of effort, time, and cost.

When designing welding conditions, the first information you need is (1) Will there be a back bead? (2) Will surplus be secured? There are two points. As for the welding parameters related to these, the former is considered to be the penetration depth, and the latter is considered to be the amount of deposited metal. Therefore, if we can know the welding conditions and their relationship, we can estimate the bead shape without extensive experiments.
The number of experiments required to select appropriate conditions can be significantly reduced.

A method of calculating the penetration depth and controlling the welding conditions is proposed in Japanese Patent Application Laid-Open No. 63-260676, but this method is double-sided layered bumashido welding, and unlike single-sided welding, the back bead is welded. There is no formation, and no flux containing metal powder is used to increase welding efficiency, making it difficult to apply to single-sided welding.

[Means to solve the problem]

The present invention performs welding after predicting the bead shape of multi-electrode single-sided welding using more than three electrodes based on the data accumulated in three-electrode single-sided welding. number of electrodes, groove shape, plate thickness, flux type, welding speed, wire diameter of each electrode, protrusion length and angular electrode spacing,
Give the welding conditions of welding current 2 welding voltage, check the expected bead penetration width, depth, and excess amount using a database prepared in advance in the microcomputer or an experimental formula, and perform welding. The feature lies in the multi-electrode single-sided Zabumarsito arc welding method.

[Effect]

FIG. 1 is a flowchart showing the multi-electrode single-sided submerged welding method of the present invention. First, the number of electrodes set N, the groove shape of the steel plate used, the plate thickness t, the type of flux, the welding speed V and the welding current of each electrode, the voltage E, the wire radius, the protrusion length La, the angle AL, the electrode spacing Dk Enter welding conditions such as Then, the electrode number and counter J are set to 1 as initial values.
Maximum penetration depth PMAX and weld metal transfer speed YS
After setting UM to zero, the already accumulated three-electrode single-sided welding data or experimental formula is read out from the computer storage device, and the penetration width W (J) and penetration depth P (J) for each electrode are determined. ). Normally, the shape of the back bead in the case of three-electrode single-sided welding is 1. It is carried out at the second electrode,
The interval between the second and third electrodes is larger than the interval between the first and second electrodes, and the third electrode forms a surface bead. Therefore, when performing single-sided welding with four or more electrodes, the first. Second
If the back bead is formed using an electrode, the current three-electrode single-sided welding data can be applied.

Next, find the amount of weld metal that controls the formation of extra metal.

In the case of single-sided welding, several tens of percent of metal powder is contained in the flux to increase welding efficiency, and the sum of the amount of metal transferred from this flux in addition to the amount that melts the wire is This is the amount of welded metal. Regarding the wire welding speed M v (g/sec), the second
As shown in the figure, the welding current is largely dominated by the welding current (2), regardless of the electrode number. In addition, the true wire protrusion length L (cm) and wire diameter D (cm) are also involved, and Mv is determined by the experimental formula (1) shown by the solid line in Figure 2.
You can find out.

Mv (g/see) = Mo + (1/1000) (4,6
6X 10' (I -L/D")' 22] ■
Welding current (A).

Mo:Ky・■.

KY constant due to flux, on the other hand, metal transfer rate Ml from flux (g/5ec
) is governed by the flux melting rate Fs (g/5ec). Now, the slag generation rate is Sv (g/5e
c), then F s = S v +M I,
Furthermore, if the ratio at which metal powder in the molten flux transfers to the weld metal (hereinafter referred to as transfer rate) is R, and the metal powder mixing ratio in the flux is C, then Ml is MI=Fs-R-C
becomes.

When these equations are rearranged using the metal transfer rate Mf, equation (2) is obtained.

Mf=Sv/(1/R-C-1) - (2) Therefore, if the blending ratio C is determined and the transfer rate R and Sv are known,
You can know Mf. Second Sv.

and R are the welding input (kW) as shown in Figures 3 and 4.
) was found to be related to Therefore, by finding Sv and R from FIGS. 3 and 4, the transition speed Mf can be found from equation (2). And wire welding speed Mv
The welding area is determined from the weld metal transfer rate YSUM, which is the sum of the transfer rate Mf and the transfer rate Mf, and the amount of excess metal is obtained by subtracting the groove area from there.

In addition, in FIG. 1, ρ in the formula for calculating the area of reinforcement is the steel density, and 3 is the groove area.

If the bead shape elements obtained in this way, that is, back penetration width M, penetration depth P, and reinforcement area S match the bead shape target values, welding is performed under these welding conditions.

If they do not match, go back to the beginning, change the welding conditions, and check again.

〔Example〕

Using the present invention, KY in equation (1) is set to 0.003. (2)
Read the formulas Sv and R from Figures 3 and 4, set the metal compounding ratio C in the flux as 0.38, and use the dialogue format with the display of the microcomputer as shown in Table 1. The electrode single-sided welding conditions were input and each bead shape element was determined, and the results shown in Table 2 were obtained. Note that here, since the surface penetration width is not given by information from the previous three-electrode single-sided welding data, an appropriate value is input. Next, using these welding conditions, 50 kg class steel 5M
490C was subjected to 4-electrode single-sided submerged arc welding. Then, the cross section of the bead after welding was measured and compared with Table 2.

Table 3 shows the results. Here, each bead shape element is as shown in Fig. 5, where P is the penetration depth and w
r and wb are the front and back weld penetration widths, respectively, and S is the sum of the bead excess amounts on the front and back sides. The expected values according to the present invention and the actual measurement results are almost the same, except for the surface penetration width of the estimated value that was set appropriately.

Table 3 [Effects of the Invention] As described above, by performing multi-electrode submerged arc welding using the present invention, it is possible to determine whether or not a back bead is formed and whether the amount of extra welding is excessive or insufficient before actual welding. Welding conditions that do not match the target values are screened out without welding, making it possible to significantly reduce the number of experiments required to select appropriate conditions, reducing the time and effort required to select conditions.

and costs can be reduced, and the labor-saving effect on industry is significant.

[Brief explanation of drawings]

Figure 1 is a flowchart showing the multi-electrode single-sided submerged AC welding method of the present invention, where J is the counter, PMAX is the maximum groove depth, YSUM is the deposited metal transfer rate, w (J), p (
J) and Mv(J) are the penetration width of the J electrode, respectively;
Penetration depth and wire welding speed, ρ is steel density, Sk
is the groove area. FIG. 2 is a graph showing the relationship between wire welding speed MY (g/5ec) and welding current I (A). FIG. 3 is a graph showing the relationship between slag production speed Sv (g/5ec) and welding input (kW). FIG. 4 is a graph showing the relationship between the metal transfer rate R from the metal powder in the flux to the weld metal and the welding input (kW). Figure 5 is a cross-sectional view of a bead in single-sided welding, where P is the penetration depth, Wl and wb are the width of the weld, and the width of the weld is the width of the weld, respectively, and S is the sum of the top and bottom bead areas. .

Claims (1)

[Claims] A database prepared in advance on a computer containing welding conditions such as the number of welding electrodes, groove shape, plate thickness, flux type, welding speed, wire diameter of each electrode, protrusion length and angle, electrode spacing, welding current, and welding voltage. A multi-electrode single-sided submerged arc welding method, characterized in that the expected bead penetration width, depth, and excess welding amount are calculated using an empirical formula, and welding conditions are determined in accordance with these and welding is performed.