JPS6010836B2 - Horizontal electroslag welding method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in lateral electroslag welding.

Welding of horizontal seams (horizontal joints) in locally assembled footing structures such as sluices, blast furnaces, hot blast furnaces, and tanks, even for plate thickness, was mostly done by hand, and automatic welding methods were not used.

There are a few cases where horizontal submerged welding or gas-shielded arc welding is performed as automatic welding, but there are problems such as discrepancies in the surface of the base metal, errors in the groove gap, and difficulty in aiming the arc at the beginning of the shoulder. However, there are various problems and it has not been put into practical use.

Therefore, the inventor's company developed the electroslag welding method, which had previously been used only for automatic vertical welding of plate thickness.
By applying it to horizontal seam welding, they not only made it possible, but also found that the properties of the welded part were extremely good, and by taking advantage of the characteristics of electroslag welding, it was extremely efficient, and developed the horizontal electroslag method. completed.

The present invention further improves this horizontal electroslag welding method, and not only improves welding efficiency but also obtains a welded part of stable quality.
Furthermore, it is intended to be applied to welding extremely thick plates.

That is, in general, in horizontal electroslag welding using a single electrode, it is possible to penetrate the upper and lower base metals of the joint by adjusting the current and voltage, but it is possible to penetrate the joint into the upper and lower base metals by adjusting the current and voltage. The thickness of the plate is up to the base material, and there is a flow of molten metal and slag in the deep part of the groove, so filling is not successful, and this part becomes the cross section shown in Figure 1, and the groove is deep inside the groove. Poor penetration may occur and it is extremely unstable.

In the figure, 1 and 2 indicate the base metal, and 3 indicates the weld metal. In addition, when applied to extremely thick plates, this tendency becomes even more pronounced, and the welding speed must be extremely slow, which makes it easier for the molten metal to precede the electrode, causing damage to the lower base metal. It also tends to be unstable. Therefore, in order to solve these problems, the present invention arranges the electrodes extremely effectively so that welding is possible even when the base material plate thickness is large. Aim for stabilizing penetration of the groove by setting the aim position of at least one of the electrodes located deep inside the groove and at the trailing position as the front end surface, and then By supplying a welding current in series between the electrodes, the slag and molten metal directly under each electrode receive force in the repulsive direction due to electromagnetic force, and the slag and molten metal are distributed deep in the plate thickness and in all directions on the surface of the groove. The fluidity of the metal increases melting at the back of the joint, and provides a new effect in which the surface bead is also beautiful.

Furthermore, since the number of electrodes is increased, it is possible to easily cope with an increase in the thickness of the base material, and the present invention can be applied to welding extremely thick (about a low rib) plates.

Next, the method of the present invention will be explained in detail based on the embodiments shown in the drawings.

As shown in Fig. 2, first, a packing agent 4 for forming a back bead is set on the back side of the joints formed on the upper and lower base materials 1 and 2, and a water-cooled steel dowel 5 is set on the front side, and then sprinkled inside the joints. Spray an appropriate amount of flux 7 using nozzle 6.

Next, two or more electrodes 8-, 98-2 are arranged at a predetermined interval in the welding direction at this joint part, but in this case, in the present invention, the electrodes 8-, 9-8-2 are placed at the top The aim position of the electrode 8-, which is to be removed, is the inner part of the bevel, and the aim position of at least one electrode 8-2 among the electrodes located in the rear row is the front end face part. In addition, in the present invention, the inner part and the front end surface part of the position of the base point refer to the position in the thickness direction of the mother village,
The former is at the 1'3 deep part of the lower groove surface, and the latter is at 1'
Point to the front side of 3. The reason why the leading electrode is aimed at the deep part of the joint is because it is an L-shaped joint, so naturally the melting position of the electrode is close to the joint surface of the upper base metal, and
This is because the slag jet flow from the tip of the electrode hits the groove surface of the upper base metal more strongly, and sufficient penetration can be obtained. If the electrode is aimed at the middle or surface of the joint, This is because the droplets generated from the electrode fall onto the center or surface of the lower base material and form a molten pool, which prevents the trailing pole from penetrating the lower base material. As a result, the weld is prevented from shifting upward or downward, and the appearance of the bead is significantly improved.

In this example, the case of two electrodes was explained, but "3
If the number of electrodes exceeds 1, the target positions of the remaining trailing electrodes are not limited.

The target position is appropriately selected depending on the plate thickness or the rate of acid dissolution. Next, the position of the preceding electrode 8-, which aims at the deep part of the joint, is, for example, as shown in Fig. 3. ) It is preferable that the distance A from the back is about 4 to 1 distance; if it is smaller than this, a short circuit will occur with the upper parent part, making welding impossible, which is not good.

If it is larger than this, the heat source will be far away, making it impossible to achieve stable penetration deep into the joint.

Further, the aiming position of the trailing electrode 8-2 aiming at the front end surface is preferably such that the distance B from the mother village surface is about 4 to 1 rib.
If it is smaller than this, an arc will occur with the front copper plate, resulting in poor welding. Moreover, if it is larger than this, the lower base material surface end face will have poor penetration. The present invention aims to provide a method that can form a stable hemline bead even when the root face is enlarged in order to facilitate hemming work. That is, the electrodes having the above configuration are connected in series and a large current is passed between the electrodes. This causes active flow to the surface of the copper plate, which contributes to the heating by the slag on the surface of the Mohamura Seki and the smooth formation of the front bead. The molten metal of the leading electrode, which is targeted at the position, moves deeper into the interior and melts the base material 2, at the same time ensuring the formation of a back bead.Here, current is applied in series between the electrodes to prevent the slag and molten metal flow. The reason why it is possible to flow in the repulsion direction will be explained with reference to the principle diagram in FIG.
First, the direction of the current in the leading electrode 8- and the trailing electrode 8-2 is reversed, and the current flows as shown by the dotted line. (Because the distance between the base metal and the electrode is much smaller than the distance between the electrodes.) Therefore, the direction of the current flowing in the slag or molten metal directly under the electrode is also reversed, and the magnetic field created by the other side's current and the own current Due to the flow, the slag and molten metal directly under the electrode are marked with an arrow (■)
1 direction (Fleming's law) causes a flow (→) as shown by the solid line, which not only allows for penetration of the upper base material joint surface, but also achieves the melting bag speed at the back of the opening. .
If the direction of this current is supplied in parallel instead of in series, this phenomenon will be weakened and there will be no Z effect. This is because, as shown in the figure, arranging the electrodes itself has the tendency to cause slag and metal flow as the electroslag phenomenon, as shown by the solid line in the figure, but by arranging them in series, this problem becomes even more While the direction is promoted for the reason mentioned above, when the Z is arranged in parallel, electromagnetism works in the opposite direction of attraction, so the direction decreases at this time and there is no effect as described above. The high current used here is 40
0 to 50M, but 60 ships or more are required.

This suppresses the advance of the molten metal and also makes the electromagnetic force strong, increasing the above effects. On the other hand, the slag flow directly under the trailing electrode 8-2 ensures penetration of the base metal 2 on the lower side of the surface edge and transfers to the surface of the steel contact plate 5, resulting in a stable bead shape (indicated by other marks in the figure). shall be. Next, a wiring diagram for passing a current in series between the electrodes will be explained with reference to FIG.

First, FIG. 5a shows a connection diagram limited to the target position of the electrodes in the method of the present invention, and is a so-called normal multi-electrode diagram in the electroslag welding method.

The leading electrode 8- and the trailing electrode 8-2 are connected in parallel to power sources 9-, 9-2, respectively.

The one shown in Fig. 5d is a modified version of Fig. 5a, and the number of electrodes is 3.
An example is shown below. The one shown in FIG. 5b is the leading electrode 8-
, and the trailing electrode 8-2 are connected in series.

That is, the leading electrode 8-2 is wired to one terminal of the welding transformer 10, and the trailing electrode 8-2 is wired to the other terminal.

The intermediate point 11 of the transformer may be connected to the welding base metal or may be disconnected during welding. The connection at the intermediate point varies depending on the transformer or power supply characteristics and the type of electrode supply speed control; The connection at the intermediate point is unnecessary, and in the case of the constant-speed electrode supply V supply method, it is necessary to flow an unbalanced current between the two poles.

This is necessary to melt the slag at the start of welding. Figure 5c
What is shown in Fig. 3 is a case where two DC constant voltage power supplies 9-, 9-2 are connected in series with a striped wire, and the series connection point is set as the midpoint. The thin material is striped. What is shown in Figures 5e and 5f is the 5th
This is an example in which the number of electrodes is four in the modified type of Figure c. Figure 5 e
What is shown in FIG.
, 8-4 are connected in series. That is, the leading electrode 8-, is connected to one terminal of the welding transformer 9, the trailing electrode group 8-2, 8-3, 8-4 is connected to the other terminal, and the electrode 8-2 is connected to the front end surface. This method is used for horizontal welding of relatively thick plates by setting welding conditions so that the current value of the leading electrode group is equal to the total current value of the trailing electrode group.
Furthermore, the one shown in Fig. 5f is also applied to a thick plate, but the leading electrode 8- and 8-3 located between the trailing pole group are connected to one terminal of the welding transformer 9, and the trailing pole group is connected to one terminal of the welding transformer 9. Electrode group 8-
2 and 8-4 are striped to the other terminal, and electrode 8-2 is arranged on the front end surface, so that there is no repulsive force not only between the electrodes 8- and 8-2, but also between the trailing electrodes. generation, ensuring stabilization of penetration.

In addition, the trailing electrode group generates an appropriate repulsion force in the welding direction as well, and supplies molten metal in the welding direction as well, making it suitable for high-speed welding. In the above configuration, the interval between the leading electrode and the trailing electrode located on the front end surface, that is, the bipolar interval, is preferably about 25 to 10 ribs.

If it is smaller than that, it is easy for the current to flow directly between the leading electrode and the trailing electrode without passing through the molten metal and the base material, which not only slows down the effective electromagnetic force but also causes melting in the center of the plate thickness. This is undesirable as it results in a welded section with a large amount of welding. Moreover, if the interval is larger than this, the repulsive force in the depth direction of the plate thickness and the surface direction due to the action of electromagnetic force becomes weaker, and the formation of diamond beads and the penetration of the front end surface become unstable.

Further, hair beads can be produced even if the root face is large, and a suitable range is 0 to 15 ribs.

The fact that the root face can be made larger is preferable because it facilitates skin matching during hemming work.

Next, regarding an example in which the method of the present invention is adopted for mechanical welding of a plate thickness of 5 mm for a hot air stove, the welding conditions are shown in Table 1, the joint shape before welding is shown in Fig. 6, and the joint shape after welding is shown in Fig. 6. Figure 7 shows a macro photograph of the weld section of the weld.

As is clear from Table 1 and FIG. 7, the difference in penetration in the plate thickness direction can be reduced, and the welding stress exerted on angular deformation can also be alleviated.

Another example is shown in Table 2 and FIG. 8, and all of them satisfied the object of the present invention and had good results.

Table 2 above describes an example of the present invention using a series connection method using a DC constant voltage as a welding power source, but the object of the present invention can also be achieved by a parallel connection method, but experiments have shown that when the root face is two or more pigs. , no hair bead is formed.

Therefore, if the root face is on two or more sides, it is necessary to perform gouging separately before welding. Below are three tables of examples (
Welding conditions) and Fig. 9 (a cross-sectional macro photograph of the welded part showing the welding results). As can be seen from Table 3, by limiting the target position of the electrode, sufficient penetration of the groove surface of the upper base material can be obtained, and it is also possible to weld the deep part of the groove and even form a back bead. became.

As detailed above, according to the present invention, it is possible to perform single-sided welding, which was previously impossible, and to obtain a stable cold bead, thereby improving the efficiency of horizontal welding and stabilizing the quality of the welded part. It has the effect of being able to secure the required amount, and has great practical value.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a welded part according to the conventional method, Fig. 2 is a perspective view illustrating the method of the present invention, Fig. 3 is a side view of the same, Fig. 4 is a side view illustrating the principle of the present invention, and Fig. 5 Figures a, b, c, d, e
, f are connection explanatory diagrams in the present invention, Figures 6 and 8 are diagrams showing the groove shape of an embodiment of the present invention, and Figure T is a diagram showing the welding after welding in the embodiment of the present invention. Sectional macro photo,
FIG. 9 is a cross-sectional macro photograph of a welded part after welding in another embodiment of the present invention. 1, 2...Mother village, 3...Welded metal, 4...
... Packing agent, 5 ... Water-cooled steel dowel, 6
...Flux spray nozzle, 7...Flux, 8...Electrode, 9.・・・． ...Power supply, 10...
...Welding transformer, 11...Transformer intermediate point,
12...Current path. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure T Figure 8 Figure 9

Claims (1)

[Claims] 1. When performing lateral horizontal electroslag welding, at least two or more electrodes are arranged at appropriate intervals in the welding direction, and among the electrodes, the electrode located at the beginning in the welding direction A horizontal electroslag welding method characterized in that the aiming position is at the back of the groove and the aiming position of at least one of the electrodes located at the rear is the front end face. 2 When performing lateral horizontal electroslag welding, at least two or more electrodes are arranged at appropriate intervals in the welding direction, and among the above electrodes, the aim position of the electrode located at the beginning in the welding direction is set at the depth of the groove. The aim position of at least one of the electrodes located at the front end and the rear end is the front end face part, and the welding current is applied in series to the electrodes so that the welding current is applied to the leading electrode and the front end face part. A horizontal electroslag welding method characterized in that the slag and molten metal directly under the row electrode repel each other and flow toward the depth of the plate thickness and toward the surface.