JP2020138237A - Electroslag welding method and magnetic field application device in electroslag welding - Google Patents

Abstract

To provide an electroslag welding method characterized by performing electroslag welding of a base material while applying a magnetic field to a molten pool in a groove portion of the base material.SOLUTION: In the electroslag welding method, a base material is welded while reciprocating a welding torch 90 between a front side position and a rear side position in a groove portion; when the welding torch 90 approaches an iron core of a magnetic filed application coil 30 at a front side that applies the magnetic field through the front side of the groove portion during the reciprocation of the welding torch 90, electric current values of the magnetic field application coil 30 at the front side are reduced and electric current values of the magnetic application coil 40 at the rear side that applies a magnetic field through the rear side of the groove portion are increased; and when the welding torch 90 approaches an iron core of a magnetic field application coil 40 at the rear side during the reciprocation of the welding torch 90, electric current values of the magnetic field application coil 40 at the rear side are reduced, and electric current values of the magnetic field application coil 30 at the front side are increased.SELECTED DRAWING: Figure 20

Description

The present invention relates to an electroslag welding method and a magnetic field application device in electroslag welding.

A magnetic stirring welding method in which a magnetic field is applied to a molten pool in arc welding and welding is performed while stirring the molten metal with a magnetic force in the rotational direction due to the magnetic field and the welding current is known (for example, Patent Document 1, Patent Document 1, 2). In Patent Documents 1 and 2, magnetic coils are arranged so as to surround the welding torch.

Japanese Unexamined Patent Publication No. 4-190976 Japanese Unexamined Patent Publication No. 8-318370

By the way, in electroslag welding, unlike arc welding, a welding wire carrying a current of several hundred amperes is supplied to the molten slag, which is a molten electrolyte, and Joule heat generation in the molten slag causes the base metal and the welding wire to be welded. It is a method of welding while melting. The welding direction is vertical, and welding proceeds from bottom to top. In addition, the groove of the base metal is covered with a water-cooled copper plate to prevent molten slag and molten metal from spilling. In electroslag welding, the front, back, left and right of the molten pool are covered with a base metal and a water-cooled copper plate, and the top and bottom of the molten pool are covered with the welded portion and the molten slag that have already been welded. Therefore, even if the coil is placed in the torch part that supplies the welding wire as in arc welding, not only is it impossible to apply an effective magnetic field to the molten pool because of the presence of molten slag, but the space at the groove is narrow in the first place. , The coil cannot be placed.

An object of the present invention is to apply a magnetic field to a molten pool in electroslag welding.

For this purpose, the present invention provides an electroslag welding method characterized in that electroslag welding of a base metal is performed while applying a magnetic field to a molten pool in the groove portion of the base metal.

The magnetic field may be a static magnetic field or a rotating magnetic field having a frequency of 1 Hz or less.

The electroslag welding method may be one in which a magnetic field is applied from the front side and the back side of the groove portion. In that case, the directions of the magnetic fields applied from the front side and the back side may be the same or opposite.

In the electroslag welding method, the welding torch is welded while reciprocating between the front side position and the back side position in the groove portion, and in the reciprocating movement of the welding torch, the welding torch moves to the groove portion. When approaching the iron core of the magnetic field application coil on the front side where the magnetic field is applied from the front side, the current value of the magnetic field application coil on the front side is reduced, and the current of the magnetic field application coil on the back side where the magnetic field is applied from the back side of the groove. By increasing the value, when the welding torch approaches the iron core of the magnetic field application coil on the back side during the reciprocating movement of the welding torch, the current value of the magnetic field application coil on the back side is reduced, and the current value of the magnetic field application coil on the front side is reduced. It may be one that increases the current value. In that case, when the welding torch is closest to the iron core of the magnetic field application coil on the front side, the current value of the magnetic field application coil on the front side is minimized, the current value of the magnetic field application coil on the back side is maximized, and the welding torch is on the back side. The current value of the magnetic field application coil on the back side may be minimized and the current value of the magnetic field application coil on the front side may be maximized when the magnetic field application coil is closest to the iron core. Further, the direction of the current flowing through the magnetic field application coil on the front side and the magnetic field application coil on the back side may be reversed for each cycle of the reciprocating motion of the welding torch. Further, when the welding torch is closest to the iron core of the magnetic field application coil on the front side or the magnetic field application coil on the back side and is stationary, the current of the magnetic field application coil on the front side and the current of the magnetic field application coil on the back side are valued. May be the same but in the opposite direction.

The front side and the back side of the groove portion may be opposite to the base material of the cooling copper plate arranged on the front surface and the back surface of the groove portion.

In the electroslag welding method, at least one of the front cooling copper plate arranged on the front surface of the groove and the back cooling copper plate arranged on the back surface is fixed to the base material, and the front cooling copper plate is fixed. The front side electromagnet and the back side so that the height of the central axis of the front side electromagnets arranged in the above from the reference surface and the height of the back side electromagnets arranged on the back side cooling copper plate from the reference surface match. It may be one that welds while moving the electromagnet. In that case, one of the front side cooling copper plate and the back side cooling copper plate may be movable in the direction in which the groove portion extends.

In the electroslag welding method, both the front side cooling copper plate arranged on the front surface of the groove and the back side cooling copper plate arranged on the back surface can be moved in the direction in which the groove extends, and the front side cooling copper plate can be used. The front cooling copper plate and the back side so that the height of the central axis of the arranged front side electromagnet from the reference surface and the height of the back side electromagnet arranged on the back side cooling copper plate from the reference surface match. The cooling copper plate may be welded while moving.

Further, in the present invention, an electromagnet for applying a magnetic field to the molten pool in the groove is arranged on the opposite side of the base material of the cooling copper plate arranged on the front surface and the back surface of the groove portion of the base material. Also provided is a magnetic field application device in electroslag welding.

The cooling copper plate may be provided with holes or grooves, and the iron core of the electromagnet may be fitted in the holes or grooves.

The magnetic current application device in electroslag welding further arranges a welding torch for welding while reciprocating between the front side position and the back side position in the groove portion, and the welding torch is reciprocated in the reciprocating movement of the welding torch. However, when approaching the iron core of the electromagnet on the front side to which the magnetic field is applied from the front side of the groove, the current value of the electromagnet on the front side is reduced, and the current value of the electromagnet on the back side to which the magnetic field is applied from the back side of the groove is reduced. When the welding torch approaches the iron core of the electromagnet on the back side in the reciprocating movement of the welding torch, the current value of the electromagnet on the back side is reduced and the current value of the electromagnet on the front side is increased. It may be.

In the magnetic field application device in electroslag welding, at least one of the front side cooling copper plate arranged on the front surface of the groove and the back side cooling copper plate arranged on the back surface is fixed to the base material, and the front side is fixed. The height of the center axis of the front side electromagnets placed on the cooling copper plate from the reference surface matches the height of the center axis of the back side electromagnets placed on the back side cooling copper plate. The electromagnet and the electromagnet on the back side may be configured to be movable.

The magnetic field application device in electroslag welding has a structure in which both the front cooling copper plate arranged on the front surface of the groove and the back cooling copper plate arranged on the back surface can move in the direction in which the groove extends. The front side so that the height of the central axis of the front side electromagnets arranged on the front side cooling copper plate from the reference surface matches the height of the back side electromagnets arranged on the back side cooling copper plate from the reference surface. The cooling copper plate and the back side cooling copper plate may be configured to be movable.

According to the present invention, it is possible to apply a magnetic field to a molten pool in electroslag welding.

(A) and (b) are perspective views of the magnetic field application device according to the first embodiment of the present invention when viewed from the front side. (A) and (b) are perspective views of the magnetic field application device according to the first embodiment of the present invention when viewed from the rear side. It is a figure which showed the position of the front side coil and the rear side coil in the magnetic field application device of 1st Embodiment of this invention. It is a figure which showed the distribution of the magnetic field at the welded part. It is a graph comparing the magnetic field distribution in the state where the coil is fitted in the water-cooled copper plate, and the magnetic field distribution in the state where the coil is not fitted in the water-cooled copper plate. It is a figure which showed the distribution of the welding current density in a molten pool. (A) and (b) are diagrams showing the flow velocity vector distribution of the molten metal on the upper surface of the molten pool. (A) and (b) are diagrams showing the flow velocity distribution of the molten metal inside the molten pool. (A) to (e) are cross-sectional photographs of the welded portion. It is a figure which showed the position of the front side coil and the rear side coil in the magnetic field application device of the 2nd Embodiment of this invention. (A) and (b) are graphs showing the distribution of the welding current density in the height direction when the welding torch is on the frontmost side and the rearmost side. It is a graph which showed the distribution of the magnetic flux density in the height direction in the configuration of Table 2. It is a graph which showed the distribution of the Lorentz force in the height direction in the configuration of Table 2. (A) and (b) are bar graphs comparing the average value of Lorentz force between the molten pool and the molten slag in the configuration of Table 2. (A) and (b) are graphs showing the distribution of welding current densities with respect to the position of the welding torch for the molten slag and the molten pool. (A) and (b) are graphs showing the distribution of Lorentz force on the front side and the rear side in the height direction when the welding torch is located on the front side and the rear side. (A) and (b) are bar graphs comparing the average values of the Lorentz forces on the front side and the rear side when the welding torch is located on the front side and the rear side between the molten pool and the molten slag. (A) and (b) are diagrams showing a problem that occurs when the directions of the magnetic poles of the front coil and the rear coil are not changed. (A) to (d) are time charts for explaining the method of reversing the applied magnetic field for electromagnetic agitation. It is a figure which looked at the structure of the magnetic field application device in 1st Example of 3rd Embodiment of this invention from the side. (A) and (b) are views showing the state of up and down movement of the front coil and the rear coil. (A) and (b) are views showing the state of up and down movement of the front coil and the rear coil. It is a figure which showed the structure of the magnetic field application apparatus in the 2nd Example of the 3rd Embodiment of this invention. It is a figure which looked at the structure of the magnetic field application device in 2nd Example of the 3rd Embodiment of this invention from the side. FIGS. (A) and (b) are views showing a state in which the front water-cooled copper plate and the rear water-cooled copper plate are moved up and down. FIGS. (A) and (b) are views showing a state in which the front water-cooled copper plate and the rear water-cooled copper plate are moved up and down.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[First Embodiment]
First, the configuration of the magnetic field application device 1 according to the first embodiment will be described. 1 (a) and 1 (b) are perspective views of the magnetic field applying device 1 according to the first embodiment as viewed from the front side (also referred to as the front side), and FIGS. 2 (a) and 2 (b) are views. It is a perspective view when the magnetic field application device 1 in the 1st Embodiment is seen from the rear side (also referred to as a back side).

As shown in FIGS. 1 (a) and 1 (b) and 2 (a) and 2 (b), the magnetic field applying device 1 according to the first embodiment includes a welding wire 5, a front water-cooled copper plate 10, and a rear side. A water-cooled copper plate 20, a front coil 30, and a rear coil 40 are included.

The welding wire 5 is inserted into the groove portion 4 formed at the abutting portion of the base materials 2 and 3. Then, it is supplied to the molten slag 6 (see FIG. 3) in the groove 4 in a state of being energized by a welding power source (not shown), and is melted by Joule heat generation in the molten slag 6, and the molten metal is melted in the molten pool 7. It is for welding sequentially from the bottom to the top by dropping it into (see FIG. 3).

The front water-cooled copper plate 10 is a water-cooled copper plate that covers the front side of the groove portion 4 of the base materials 2 and 3. The front water-cooled copper plate 10 is provided with an inflow port (not shown) for flowing in cooling water for water cooling and an outflow port (not shown) for flowing out cooling water for water cooling. The rear water-cooled copper plate 20 is a water-cooled copper plate that covers the rear side of the groove portion 4 of the base materials 2 and 3. The rear water-cooled copper plate 20 is also provided with an inflow port (not shown) for flowing in cooling water for water cooling and an outlet (not shown) for flowing out cooling water for water cooling.

The front coil 30 is a magnetic coil arranged on the front water-cooled copper plate 10. The front coil 30 is energized by a coil power source (not shown) to generate a magnetic field, and the magnetic field is applied to the molten pool 7 (see FIG. 3). The rear coil 40 is a magnetic coil arranged on the posterior water-cooled copper plate 20. The rear coil 40 is also energized by a coil power source (not shown) to generate a magnetic field, and the magnetic field is applied to the molten pool 7 (see FIG. 3).

Here, FIG. 1A is a perspective view of the magnetic field applying device 1 before fitting the front coil 30, and FIG. 1B is a perspective view of the magnetic field applying device 1 after fitting the front coil 30. is there. When the front water-cooled copper plate 10 moves upward according to the progress of welding, the front coil 30 also needs to move upward. Therefore, as shown in the figure, the front water-cooled copper plate 10 is provided with a hole 11, and the hole 11 is provided. The iron core 31 of the front coil 30 is fitted in 11.

2 (a) is a perspective view of the magnetic field applying device 1 before fitting the rear coil 40, and FIG. 2 (b) is a perspective view of the magnetic field applying device 1 after fitting the rear coil 40. Is. Since the rear water-cooled copper plate 20 is fixed to the base materials 2 and 3, as shown in the figure, the rear water-cooled copper plate 20 is provided with a groove 21 in the vertical direction, and the iron core 41 of the rear coil 40 is a groove thereof. While still fitted to 21, it moves upward as the welding progresses.

In the present embodiment, as shown in FIGS. 1 (a) and 1 (b) and FIGS. 2 (a) and 2 (b), the front coil 30 is arranged on the front side of the groove portion 4 and is located on the rear side. The coil 40 is arranged on the back side of the groove portion 4. Further, the front water-cooled copper plate 10 is arranged on the front surface, that is, the front surface of the groove portion 4, and the rear water-cooled copper plate 20 is arranged on the back surface, that is, the back surface of the groove portion 4. .. In this state, the arrangement position of the front coil 30 is on the side opposite to the base materials 2 and 3 of the front water-cooled copper plate 10, and the arrangement position of the rear coil 40 is the base material 2 and 3 of the rear water-cooled copper plate 20. Can be said to be on the other side.

Further, in the present embodiment, as shown in FIGS. 1 (a) and 1 (b) and FIGS. 2 (a) and 2 (b), a plane passing through the center of the base materials 2 and 3 and parallel to the base materials 2 and 3. The direction perpendicular to the welding progress direction and toward the right side when viewed from the front side of the base materials 2 and 3 is defined as the positive direction of the X-axis. Further, the direction toward the rear side of the base materials 2 and 3 in the direction perpendicular to the plane parallel to the base materials 2 and 3 passing through the center of the base materials 2 and 3 is defined as the positive direction of the Y axis. Further, the direction of welding on a plane passing through the center of the base materials 2 and 3 and parallel to the base materials 2 and 3 is set to the positive direction of the Z axis.

Next, the specifications of the front coil 30 and the rear coil 40 in the magnetic field application device 1 of the first embodiment will be described. The table below shows the specifications of the front coil 30 and the rear coil 40.

As shown in the table, the ampere turn of the front coil 30 is 6000 AT, and the ampere turn of the rear coil 40 is 9000 AT. Further, the sizes of the iron core 31 of the front coil 30 and the iron core 41 of the rear coil 40 are both 20 mm in diameter and 60 mm in length.

Next, the arrangement of the front coil 30 and the rear coil 40 in the magnetic field application device 1 of the first embodiment will be described. FIG. 3 is a diagram showing the positions of the front coil 30 and the rear coil 40 in the magnetic field application device 1. In the present embodiment, as shown in the figure, the position of the axis of the iron core 31 of the front coil 30 and the iron core 41 of the rear coil 40 is 20 mm to 25 mm below the tip of the welding wire 5. It is arranged like this. Since the distance from the tip of the welding wire 5 to the molten pool 7 is 10 mm to 15 mm, with such an arrangement, the upper ends of the iron core 31 and the iron core 41 are compared with the interface 8 between the molten slag 6 and the molten pool 7. Then, the height becomes almost the same or lower.

Next, the distribution of the magnetic field applied to the welded portion by the magnetic field applying device 1 of the present embodiment will be described. FIG. 4 is a diagram showing the distribution of the magnetic field at the welded portion. Specifically, it is a simulation result of the distribution of the magnetic field at the welded part. By arranging the front coil 30 and the rear coil 40 shown in FIG. 3, the magnetic field can be applied to the molten pool 7 while keeping the strength of the magnetic field applied to the molten slag 6 through which the welding current is flowing low. I understand.

Next, in the magnetic field application device 1 of the present embodiment, the case where the coil is fitted to the water-cooled copper plate and the case where the coil is not fitted will be compared and described. FIG. 5 is a graph comparing the magnetic field distribution in the state where the coil is fitted in the water-cooled copper plate and the magnetic field distribution in the state where the coil is not fitted in the water-cooled copper plate. Specifically, the magnetic field distribution of the former is a state in which the iron core 31 of the front coil 30 is fitted in the hole 11 of the front water-cooled copper plate 10 and the iron core 41 of the rear coil 40 is fitted in the groove 21 of the rear water-cooled copper plate 20. It is a simulation result of the magnetic field distribution of the molten pool 7 in. On the other hand, the latter magnetic field distribution is a state in which the iron core 31 of the front coil 30 is not fitted in the hole 11 of the front water-cooled copper plate 10 and the iron core 41 of the rear coil 40 is not fitted in the groove 21 of the rear water-cooled copper plate 20. This is a simulation result of the magnetic field distribution of the molten pool 7 in a state where the tip of the iron core 41 is separated from the molten pool 7. In the graph, the positive direction of the front-back direction position indicates the direction on the front side of the magnetic field application device 1. From the graph, it can be seen that the strength of the magnetic field is increased when the coil is fitted to the water-cooled copper plate than when the coil is not fitted to the water-cooled copper plate. The increase in the strength of the magnetic field is remarkable, especially at the interface 8 before and after the molten pool 7, and can be increased about twice.

Next, the distribution of the welding current density of the molten pool 7 in the magnetic field applying device 1 of the present embodiment will be described. FIG. 6 is a diagram showing the distribution of welding current densities in the molten pool 7. Specifically, it is a simulation result of the distribution of the welding current density observed from the rear side by applying a DC voltage of 30 V to the welding wire 5 while applying a magnetic field to the molten pool 7. From Figure 5, the welding current density has become approximately ^{1.0 × 10 5 [A / m} 2] ~3.2 × 10 5 [A / m 2] in the molten pool 7, the welding current in the molten pool 7 You can see that is flowing. Therefore, electromagnetic stirring can be caused by applying a static magnetic field to the welding current of the molten pool 7.

Next, the flow velocity distribution of the molten metal on the upper surface of the molten pool 7 generated by the magnetic field applying device 1 of the present embodiment will be described. 7 (a) and 7 (b) are diagrams showing the flow velocity vector distribution of the molten metal on the upper surface of the molten pool 7. Specifically, it is a simulation result of the flow of molten metal generated by electromagnetic stirring inside the molten pool 7. FIG. 7A shows a case where the direction of the magnetic field generated by the front coil 30 and the direction of the magnetic field generated by the rear coil 40 are the same, and FIG. 7B shows the direction of the magnetic field generated by the front coil 30. The case where the direction of the magnetic field generated by the rear coil 40 is opposite to that of the magnetic field is shown. Since the largest Lorentz force acts on the portion of the molten pool 7 closest to the iron cores 31 and 41, the flow velocity is the fastest on the front side and the rear side of the molten pool 7 and is about 0.2 m / s. In FIG. 7A, since the direction of the magnetic field generated by the front coil 30 and the direction of the magnetic field generated by the rear coil 40 are the same, the flow directions are the same on the front side and the rear side of the molten pool 7, and the melt is melted. An S-shaped flow is generated in the horizontal plane of the pond 7. Further, as can be seen from FIGS. 7 (a) and 7 (b), the flow velocity distribution is asymmetrical. Therefore, reversing the direction of the applied magnetic field at a low frequency of 1.0 Hz or less is effective for averaging the stirring effect. However, when the frequency is 1.0 Hz or higher, the Lorentz force is reversed before the flow grows and the stirring effect becomes smaller, so 1.0 Hz or lower is appropriate.

Next, the flow velocity distribution of the molten metal inside the molten pool 7 generated by the magnetic field applying device 1 of the present embodiment will be described. 8 (a) and 8 (b) are views showing the flow velocity distribution of the molten metal inside the molten pool 7. FIG. 8A shows the flow velocity distribution when a static magnetic field is applied. Here, the magnetomotive forces of the front coil 30 and the rear coil 40 are both set to 6000 AT, and the direction of the magnetic field generated by the front coil 30 and the direction of the magnetic field generated by the rear coil 40 are the same. Further, FIG. 8B shows a flow velocity distribution when a rotating magnetic field of 10 Hz rotating in the horizontal plane of the molten pool 7 is applied. Here, one front coil 30 and two rear coils 40 are used, and the magnetomotive force of each coil is 6000 AT. In each of FIGS. 8A and 8B, the upper flow velocity distribution map shows the upper surface flow velocity distribution map of the molten pool 7, and the central flow velocity distribution map is the flow velocity distribution map of the central surface of the molten pool 7. The lower flow velocity distribution map shows the flow velocity distribution map of the lower surface of the molten pool 7. Comparing FIG. 8A and FIG. 8B, it can be seen that the flow velocity when a rotating magnetic field of 10 Hz is applied is clearly smaller by an order of magnitude or more, and the stirring effect cannot be expected.

Next, the cross-sectional observation result of the welded portion 9 (see FIG. 3) will be described. 9 (a) to 9 (e) are cross-sectional photographs of the welded portion 9. Specifically, FIGS. 9 (a), 9 (b), (c), (d), and (e) show a case where a static magnetic field is applied and a case where a rectangular wave magnetic field having a frequency of 0.25 Hz is applied. (1st time), when a rectangular wave magnetic field with a frequency of 0.25 Hz is applied (2nd time), when a rectangular wave magnetic field with a frequency of 1.0 Hz is applied, and when no magnetic field is applied. is there. When these cross-sectional photographs are arranged in ascending order of grain boundaries, (a) <(b) and (c) <(d) <(e) are obtained as shown by arrows in the photographs. Compared with the case where the magnetic field of (e) is not applied, the crystal grain boundary becomes smaller when the static magnetic field of (a) is applied, and the effect of refining the grain boundary by electromagnetic stirring is obtained. Can be done. Further, when a rectangular wave magnetic field is applied at low frequencies (less than 1.0 Hz) of (b) and (c), the same effect can be obtained although it is inferior when the static magnetic field of (a) is applied. Is done.

In the present embodiment, the front coil 30 is arranged outside the front water-cooled copper plate 10 arranged on the front side of the groove portion 4, and the rear coil 30 is arranged outside the rear water-cooled copper plate 20 arranged on the rear side of the groove portion 4. 40 was placed. Specifically, a hole 11 is dug in the front water-cooled copper plate 10, the iron core 31 of the front coil 30 is fitted into the hole 11, a groove 21 is dug in the rear water-cooled copper plate 20, and the rear coil 40 is formed in the groove 21. The iron core 41 was fitted. As a result, the magnetic field strength that can be applied to the molten pool 7 is improved, and the magnetic stirring effect of the molten pool 7 is also improved.

[Second Embodiment]
Since the configuration of the magnetic field applying device 1'in the second embodiment is the same as that shown in FIGS. 1 (a) and 1 (b) and FIGS. 2 (a) and 2 (b), the description thereof will be omitted.

Next, the arrangement of the front coil 30 and the rear coil 40 in the magnetic field application device 1'of the second embodiment will be described. FIG. 10 is a diagram showing the positions of the front coil 30 and the rear coil 40 in the magnetic field application device 1'. In the present embodiment, the specifications of the front coil 30 and the rear coil 40 are set as shown in Table 2 below.

That is, as shown in FIG. 10, the position of the axis of the iron core 31 of the front coil 30 and the iron core 41 of the rear coil 40 is 20 mm below the interface 8 between the molten slag 6 and the molten pool 7. It is arranged so that it becomes. This is because the magnetic field applied to the molten slag 6 is desired to be reduced. Further, as shown in Table 2, the sizes of the iron core 31 of the front coil 30 and the iron core 41 of the rear coil 40 are both 20 mm in diameter and 60 mm in length. In this state, as shown in Table 2, the Lorentz force acting on the molten pool 7 and the molten slag 6 when a magnetomotive force of 3000 AT (ampere turn) was applied to the front coil 30 and the rear coil 40 was estimated.

Further, in the electric slag welding, the welding torch 90 is slid in the front-rear direction in order to weld the base materials 2 and 3 evenly in the thickness direction. Although FIG. 3 did not show the sliding motion of the welding torch 90, FIG. 10 shows that the welding torch 90 slides with a width of 16 mm in the thickness direction. Specifically, it is assumed that the sliding motion is 9 mm to the front side and 7 mm to the rear side from the center in the thickness direction.

11 (a) and 11 (b) are graphs showing the distribution of the welding current density in the height direction when the welding torch 90 is at the frontmost side and at the rearmost side, respectively. In these graphs, the welding current densities on the front side of the molten pool 7 and the molten slag 6 are shown by solid lines, and the welding current densities on the rear side of the molten pool 7 and the molten slag 6 are shown by broken lines. From FIG. 11A, when the welding torch 90 comes to the front side, comparing the welding current density on the front side of the molten pool 7 with the welding current density on the front side of the molten slag 6, the molten slag 6 is more than the molten pool 7. It can be seen that the welding current density is higher. However, the absolute value of the welding current density on the rear side of the molten slag 6 is smaller than that of the molten pool 7 because the welding torch 90 is separated. On the other hand, from FIG. 11B, it can be seen that the opposite is true when the welding torch 90 is on the rear side.

FIG. 12 is a graph showing the distribution of the magnetic flux density in the height direction in the configuration shown in Table 2. In this graph, the magnetic flux densities on the front side of the molten pool 7 and the molten slag 6 are shown by a solid line, and the magnetic flux densities on the rear side of the molten pool 7 and the molten slag 6 are shown by a broken line. From FIG. 12, it can be seen that the magnetic field strength of the molten slag 6 is lower than that of the molten pool 7 as an effect of lowering the positions of the iron core 31 and the iron core 41.

FIG. 13 is a graph showing the distribution of Lorentz force in the height direction in the configuration shown in Table 2. In this graph, the Lorentz force on the front side of the molten pool 7 and the molten slag 6 when the welding torch 90 is located on the front side is shown by a solid line, and the Lorentz force of the molten pool 7 and the molten slag 6 when the welding torch 90 is located on the rear side is shown by a solid line. The Lorentz force on the posterior side is shown by a broken line.

14 (a) and 14 (b) are bar graphs comparing the average value of Lorentz force between the molten pool 7 and the molten slag 6 in the configuration of Table 2. Specifically, FIG. 14A shows the average value of the Lorentz force acting on the front side of the molten pool 7 and the molten slag 6 when the welding torch 90 is located on the front side, which is shown by a solid line in FIG. Further, FIG. 14B shows the average value of the Lorentz force acting on the rear side of the molten pool 7 and the molten slag 6 when the welding torch 90 is located on the rear side, which is shown by the broken line in FIG. From FIGS. 14 (a) and 14 (b), it can be seen that a larger Lorentz force is acting in the molten pool 7 than in the molten slag 6.

Next, a method of further suppressing the electromagnetic stirring effect generated in the molten slag 6 will be described.

15 (a) and 15 (b) are graphs showing the distribution of welding current densities with respect to the position of the welding torch 90 for the molten slag 6 and the molten pool 7, respectively. In each graph, the welding current density on the front side of the molten slag 6 or the molten pool 7 is shown by a solid line, and the welding current density on the rear side of the molten slag 6 or the molten pool 7 is shown by a broken line. Comparing the distribution of the welding current density in the middle of the molten slag 6 in FIG. 15 (a) with the distribution of the welding current density in the middle of the molten pool 7 in FIG. 15 (b), the former is two with respect to the position of the welding torch 90. While the latter has a shape close to a linear function, the latter has a shape close to a linear function with respect to the position of the welding torch 90. That is, the molten pool 7 is less dependent on the position of the welding torch 90 in the welding current density than the molten slag 6. Therefore, when the welding torch 90 is closest to the iron core 31 of the front coil 30, the current value of the front coil 30 may be minimized and the current value of the rear coil 40 may be maximized. This makes it possible to apply a significant magnitude of electromagnetic force to the molten pool 7 while effectively suppressing the electromagnetic force acting on the molten slag 6. On the contrary, when the welding torch 90 is closest to the iron core 41 of the rear coil 40, the current value of the rear coil 40 may be minimized and the current value of the front coil 30 may be maximized.

By such a method of energizing the front coil 30 and the rear coil 40, the molten pool 7 can be electromagnetically agitated to a significant size and the molten slag 6 can be suppressed, and the molten slag 6 is caught in the molten pool 7. There will be no such thing. As a result, the mechanical strength of the welded portion 9 is improved.

Therefore, the Lorentz force distribution was estimated by adopting the method of changing the current values of the front coil 30 and the rear coil 40 in synchronization with the position of the welding torch 90 described above. The specifications of the front coil 30 and the rear coil 40 at that time are shown in Table 3 below.

In FIGS. 11A and 11B, when the welding torch 90 is located on the front side or the rear side, the welding current density on the opposite side drops to less than half of the maximum value of the welding current density at the position of the welding torch 90. Was there. It is necessary to increase the applied magnetic field in order to compensate for the decrease in the welding current density. Therefore, as shown in Table 3, the positions of the iron core 31 of the front coil 30 and the iron core 41 of the rear coil 40 are raised by 10 mm, and the energization current value is also tripled for the front coil 30 and doubled for the rear coil 40. I made it big.

16 (a) and 16 (b) show the distribution of the Lorentz force on the front side of the molten pool 7 and the molten slag 6 when the welding torch 90 is located on the front side and the rear side, respectively, and the welding torch 90 is on the front side. It is a graph which showed the distribution in the height direction of the Lorentz force on the rear side of the molten pool 7 and the molten slag 6 when it is located on the rear side. Of these, FIG. 16A shows the distribution of Lorentz force on the front side of the molten pool 7 and the molten slag 6 when the welding torch 90 is located on the rear side in the configuration shown in Table 3 with a thick line. In FIG. 16A, the distribution of the Lorentz force in the configuration of Table 2 is also shown by a thin line, but in the case of the configuration of Table 3 shown by a thick line, the Lorentz force can be suppressed more by the molten slag 6. looks like. As shown in FIG. 16B, the same applies to the Lorentz force on the rear side when the welding torch 90 is located on the front side and the rear side.

In order to make this quantitatively easy to understand, a graph evaluated by an average value is shown. 17 (a) and 17 (b) show the average value of the Lorentz force on the front side of the molten pool 7 and the molten slag 6 when the welding torch 90 is located on the front side and the rear side, respectively, and the welding torch 90 is on the front side and the rear side. It is a bar graph comparing the average value of the Lorentz force on the posterior side of the molten pool 7 and the molten slag 6 when it is located in the molten pool 7 and the molten slag 6. Of these, FIG. 17A shows the average value of the Lorentz force on the front side of the molten pool 7 and the molten slag 6 when the welding torch 90 is located on the front side and the rear side. From FIG. 17A, it can be seen that the Lorentz force of the molten slag 6 can be further suppressed in the configuration of Table 3 as compared with the configuration of Table 2. As shown in FIG. 17B, the same applies to the Lorentz force on the rear side when the welding torch 90 is located on the front side and the rear side.

Based on the above, the distribution of Lorentz force in the configuration shown in Table 3 is estimated, and the position of the welding torch 90 and the current values of the front coil 30 and the rear coil 40 are changed in synchronization to obtain the electromagnetic stirring effect of the molten slag 6. It was found that it can be suppressed, but a problem arises when the energization direction of the front coil 30 and the rear coil 40, in other words, the direction of the magnetic poles is not changed.

18 (a) and 18 (b) are diagrams showing such a problem. As shown in FIG. 18A, even when a magnetic field for electromagnetic agitation is not applied to the molten slag 6, a pinch force acts due to the welding current, and a strong flow S from top to bottom is generated along the welding wire 5. It is happening. The flow S is bent in the left-right direction according to the direction of the Lorentz force due to the action of the applied magnetic field for electromagnetic agitation. In FIG. 18B, since the magnetic field M in the depth direction of the paper surface is applied, the Lorentz force F acts in the right direction, whereby the flow S is curved in the right direction. As a result, the molten slag 6 has temperature unevenness in the left-right direction, and the amount of the base materials 2 and 3 is different.

Therefore, in the present embodiment, the direction of the applied magnetic field for electromagnetic agitation is periodically reversed to equalize the amount of penetration of the base materials 2 and 3 on the left and right.

19 (a) to 19 (d) are time charts for explaining a method of reversing an applied magnetic field for electromagnetic agitation. In these time charts, as shown in FIG. 19A, the time when the welding torch 90 is stationary on the rear side is set to time t0 to time t1, and the time when the welding torch 90 is moving from the rear side to the front side. Is time t1 to time t2, the time when the welding torch 90 is stationary on the front side is time t2 to time t3, and the time when the welding torch 90 is moving from the front side to the rear side is time t3 to time t0.

Of these, FIG. 19 (c) shows an energization pattern when the direction of the magnetic poles is reversed for each movement cycle of the welding torch 90. Further, FIG. 19D shows an energization pattern when the directions of the magnetic poles are changed when the welding torch 90 is on the front side or the rear side. Further, for comparison, FIG. 19B also shows an energization pattern when the directions of the magnetic poles of the front coil 30 and the rear coil 40 are not changed according to the sliding motion of the welding torch 90. In the energization pattern of FIG. 19B, the maximum value and the minimum value of the current value of the front coil 30 are set to "maximum front coil" and "minimum front coil", respectively, and the maximum value of the current value of the rear coil 40 is defined. Assuming that the minimum values are "maximum rear coil" and "minimum rear coil", these values are shown as they are even in the energization patterns shown in FIGS. 19 (c) and 19 (d) when the directions of the magnetic poles are not reversed. When the direction of is reversed, these values are shown with a minus.

In the present embodiment, when the welding torch 90 is closest to the iron core 31 of the front coil 30, the current value of the front coil 30 is minimized and the current value of the rear coil 40 is maximized to maximize the welding torch 90. Is closest to the iron core 41 of the rear coil 40, the current value of the rear coil 40 is minimized and the current value of the front coil 30 is maximized, but this is not limited to this. When the welding torch 90 approaches the iron core 31 of the front coil 30, the current value of the front coil 30 is decreased to increase the current value of the rear coil 40, and the welding torch 90 becomes the iron core 41 of the rear coil 40. When approaching, the current value of the rear coil 40 may be decreased to increase the current value of the front coil 30.

[Third Embodiment]
The third embodiment is an embodiment relating to a mechanism for moving the front coil 30 and the rear coil 40 with respect to the base materials 2 and 3.

In the first embodiment of the third embodiment, the magnetic field application device 1 of the first embodiment is used. That is, the structure of the first embodiment of the third embodiment is as shown in FIGS. 1 (a), (b), 2 (a), (b), and 3. In this magnetic field application device 1, as described above, the rear water-cooled copper plate 20 is fixed to the base materials 2 and 3 and does not move, and the front water-cooled copper plate 10 and the front coil 30 and the rear coil 40 are used as the base materials 2 and 2. Move against 3.

FIG. 20 is a side view of the configuration of the magnetic field application device 1 in the first embodiment. As shown in the figure, the front water-cooled copper plate 10, the front coil 30, and the rear coil 40 are fixed to the front vertical lift mechanism 50 and the rear vertical lift mechanism 60, which are independent of each other, respectively. Specifically, the front vertical lifting mechanism 50 presses the front water-cooled copper plate 10 and the front coil 30 against the base materials 2 and 3 by the front frame 51, and the rear vertical lifting mechanism 60 is reared by the rear frame 61. The side coil 40 is pressed against the rear water-cooled copper plate 20. As a result, the front vertical lift mechanism 50 raises and lowers the front water-cooled copper plate 10 and the front coil 30 up and down along the base materials 2 and 3 to be welded, and the rear vertical lift mechanism 60 raises the rear coil 40 to the rear side. It is moved up and down along the groove 21 dug in the water-cooled copper plate 20. As shown in the figure, the front vertical elevating mechanism 50 is also provided with a welding torch 90 for feeding the welding wire 5.

21 (a) and 21 (b) and 22 (a) and 22 (b) are views showing a state in which the front coil 30 and the rear coil 40 are moved up and down. Specifically, FIGS. 21 (a) and 21 (b) show a state in which the front coil 30 and the rear coil 40 are in the initial positions, and FIG. 21 (a) is a view of the front coil 30 and the rear coil 40 viewed from the front. 21 (b) is a view of it from the rear side. 22 (a) and 22 (b) show a state in which the front coil 30 and the rear coil 40 are moving for welding, and FIG. 22 (a) is a view of the front coil 30 and the rear coil 40 viewed from the front side. FIG. 22B is a view of the rear side.

As shown in FIGS. 21 (a) and 22 (a), a gantry 70 is fixed to the base material 3, and the front vertical elevating mechanism 50 is moved up and down along the gantry 70 by moving gears 52 and 53. Go up and down. Further, the front vertical elevating mechanism 50 has a height sensor 54 that detects the height of the front coil 30. As the height sensor 54, a non-contact range finder or the like using infrared rays or the like can be used. A reflector 55 may be provided on the reference surface L1, and the height sensor 54 may measure the distance from the reflector 55. The reference surface L1 may be provided at any height, but in the figure, it is provided at the height of the upper end of the rear water-cooled copper plate 20. Further, the front side vertical lift mechanism 50 is also provided with a front side controller 56 that controls transmission of height information detected by the height sensor 54 to the rear side vertical lift mechanism 60.

As shown in FIGS. 21 (b) and 22 (b), a gantry 80 is also fixed to the base material 3, and the rear vertical elevating mechanism 60 is moved up and down along the gantry 80 by moving gears 62 and 63. Go up and down. Further, the rear side vertical lift mechanism 60 has a height sensor 64 that detects the height of the rear side coil 40. As the height sensor 64, a non-contact range finder or the like using infrared rays or the like can be used. A reflector 65 may be provided on the same reference surface L1 as shown in FIGS. 21 (a) and 22 (a), and the height sensor 64 may measure the distance from the reflector 65. Further, when height information is transmitted from the front vertical lifting mechanism 50 to the rear vertical lifting mechanism 60, the rear coil so that the transmitted height and the height detected by the height sensor 64 match. A rear controller 66 that controls the up and down movement of the 40 is also provided.

First, before the start of welding, as shown in FIGS. 21 (a) and 21 (b), the heights (reference heights) of the front side vertical lift mechanism 50 and the rear side vertical lift mechanism 60 with reference to the reference surface L1 are set. The positions of the front vertical lift mechanism 50 and the rear vertical lift mechanism 60 are adjusted so as to match. As a result, the height of the front coil 30 and the height of the rear coil 40 match. This state is the initial state.

Next, when welding is started, the front vertical elevating mechanism 50 moves upward as the welding progresses, and the height A1 with respect to the reference surface L1 becomes shorter as shown in FIG. 22A. The front controller 56 sequentially transmits information on the height A1 from the initial state of the front vertical lift mechanism 50 to the posterior controller 66. As a result, in the posterior vertical lift mechanism 60, as shown in FIG. 22B, the height sensor 64 measures the height B1 from the reference surface L1 of the posterior vertical lift mechanism 60. Then, the rear controller 66 controls the position of the posterior vertical lift mechanism 60 so that the height A1 transmitted from the front controller 56 and the height B1 measured by the height sensor 64 match. To do.

In the first embodiment, the front controller 56 transmits the information of the height A1 to the posterior controller 66, and the posterior controller 66 is on the posterior side so that the height A1 and the height B1 match. The position of the vertical elevating mechanism 60 is controlled, but the present invention is not limited to this. For example, a common controller is provided on the front side and the rear side, and the front side controller 56 and the rear side controller 66 transmit information on height A1 and height B1 to this common controller, respectively, and this common controller. Sends a signal to control the position of the front vertical lift mechanism 50 to the front controller 56, or sends a signal to control the position of the rear vertical lift mechanism 60 to the rear side so that the height A1 and the height B1 match. It may be sent to the controller 66.

As described above, in the first embodiment of the third embodiment, the positions of the front coil 30 and the rear coil 40 are aligned with each other in the height direction of the molten slag 6 and the molten pool 7. As a result, the violence of the molten slag 6 due to excitation can be suppressed, so that the bead shape can be stabilized and inclusions and the like can be prevented from being mixed.

Further, in the first embodiment of the third embodiment, the rear water-cooled copper plate 20 is fixed to the base materials 2 and 3. As a result, leakage of the molten slag 6 from the rear side can be suppressed, so that the bead shape can be stabilized.

In the above, the front water-cooled copper plate 10 moves along the base materials 2 and 3, and the rear water-cooled copper plate 20 is fixed to the base materials 2 and 3, but the present invention is not limited to this. The front water-cooled copper plate 10 is fixed to the base materials 2 and 3, and the rear water-cooled copper plate 20 moves along the base materials 2 and 3, and both the front water-cooled copper plate 10 and the rear water-cooled copper plate 20 are the base materials 2 and 2. A configuration fixed to 3 may be adopted. That is, at least one of the front water-cooled copper plate 10 and the rear water-cooled copper plate 20 may be fixed to the base materials 2 and 3.

In the second embodiment of the third embodiment, the magnetic field application device 1'in which the rear water-cooled copper plate 20 of the magnetic field application device 1 in the first embodiment is replaced with the same type as the front water-cooled copper plate 10 is used. Use. FIG. 23 is a diagram showing the structure of the magnetic field application device 1'. In this magnetic field application device 1', the component corresponding to the front side water-cooled copper plate 10 of the magnetic field application device 1 is the front side water-cooled copper plate 10a, and the component corresponding to the rear side water-cooled copper plate 20 of the magnetic field application device 1 is the rear side water-cooled copper plate 10b. And. Then, in this magnetic field application device 1', not only the iron core 31 of the front coil 30 fits into the hole 11a of the front water-cooled copper plate 10a and moves together, but also the iron core 41 of the rear coil 40 also moves with the rear water-cooled copper plate 10b. It is a mechanism that fits into the hole 11b and moves together.

FIG. 24 is a side view of the configuration of the magnetic field application device 1'in the second embodiment. As shown in the figure, the front side water-cooled copper plate 10a and the rear side water-cooled copper plate 10b are fixed to the front side vertical lifting mechanism 50a and the rear side vertical lifting mechanism 50b, which are independent of each other, respectively. Specifically, the front vertical elevating mechanism 50a presses the front water-cooled copper plate 10a against the base materials 2 and 3 by the front frame 51a, and the rear vertical elevating mechanism 50b presses the rear water-cooled copper plate 10b by the rear frame 51b. It is pressed against the base materials 2 and 3. As a result, the front side vertical lift mechanism 50a and the rear side vertical lift mechanism 50b move the front side water-cooled copper plate 10a and the rear side water-cooled copper plate 10b up and down along the base materials 2 and 3 to be welded. As shown in the figure, the front vertical elevating mechanism 50a is also provided with a welding torch 90 for feeding the welding wire 5.

25 (a) and 25 (b) and 26 (a) and 26 (b) are views showing the vertical movement of the front water-cooled copper plate 10a and the rear water-cooled copper plate 10b. Specifically, FIGS. 25 (a) and 25 (b) show a state in which the front side water-cooled copper plate 10a and the rear side water-cooled copper plate 10b are in the initial positions, and FIG. 25 (a) is a view of them viewed from the front side. , FIG. 25 (b) is a view of it from the rear side. Further, FIGS. 26 (a) and 26 (b) show a state in which the front water-cooled copper plate 10a and the rear water-cooled copper plate 10b are moving for welding, and FIG. 26 (a) is a view of the front water-cooled copper plate 10a as viewed from the front side. Yes, FIG. 26 (b) is a view of it from the rear side.

As shown in FIGS. 25 (a) and 26 (a), a gantry 70 is fixed to the base material 3, and the front vertical elevating mechanism 50a is moved up and down along the gantry 70 by moving gears 52a and 53a. Go up and down. Further, the front vertical elevating mechanism 50a has a height sensor 54a that detects the height of the front water-cooled copper plate 10a and the front coil 30. As the height sensor 54a, a non-contact range finder or the like using infrared rays or the like can be used. A reflector 55a may be provided on the reference surface L2, and the height sensor 54a may measure the distance from the reflector 55a. The reference surface L2 may be provided at any height, but in the figure, it is provided at the height of the welding start position. Further, the front vertical elevating mechanism 50a is also provided with a front controller 56a that controls transmission of height information detected by the height sensor 54a to the rear vertical elevating mechanism 50b.

As shown in FIGS. 25 (b) and 26 (b), a gantry 80 is also fixed to the base material 3, and the rear vertical elevating mechanism 50b is moved up and down along the gantry 80 by moving gears 52b and 53b. Go up and down. Further, the rear side vertical elevating mechanism 50b has a height sensor 54b that detects the height of the rear side water-cooled copper plate 10b and the rear side coil 40. As the height sensor 54b, a non-contact range finder or the like using infrared rays or the like can be used. A reflector 55b may be provided on the same reference surface L2 as shown in FIGS. 25 (a) and 26 (a), and the height sensor 54b may measure the distance from the reflector 55b. Further, when the height information is transmitted from the front vertical lifting mechanism 50a to the rear vertical lifting mechanism 50b, the rear water cooling is performed so that the transmitted height and the height detected by the height sensor 54b match. A rear controller 56b that controls the vertical movement of the copper plate 10b is also provided.

First, before the start of welding, as shown in FIGS. 25 (a) and 25 (b), the heights of the front water-cooled copper plate 10a and the front coil 30 with reference to the reference surface L2 and the rear side with reference to the reference surface L2. Match the heights of the water-cooled copper plate 10b and the rear coil 40. This state is the initial state.

Next, when welding is started, the front vertical elevating mechanism 50a moves upward as the welding progresses, and the height A2 with respect to the reference surface L2 becomes longer as shown in FIG. 26A. The front controller 56a sequentially transmits information on the height A2 of the front water-cooled copper plate 10a from the initial state to the posterior controller 56b. As a result, in the posterior vertical lift mechanism 50b, as shown in FIG. 26B, the height sensor 54b measures the height B2 of the posterior water-cooled copper plate 10b from the reference surface L2. Then, the rear controller 56b controls the position of the posterior water-cooled copper plate 10b so that the height A2 transmitted from the front controller 56a and the height B2 measured by the height sensor 54b coincide with each other. ..

In the second embodiment, the front controller 56a transmits the information of the height A2 to the posterior controller 56b, and the posterior controller 56b is on the posterior side so that the height A2 and the height B2 match. The position of the water-cooled copper plate 10b is controlled, but the position is not limited to this. For example, a common controller is provided on the front side and the rear side, and the front side controller 56a and the rear side controller 56b transmit information on the height A2 and the height B2 to this common controller, respectively, and this common controller. Sends a signal to control the position of the front water-cooled copper plate 10a to the front controller 56a, and sends a signal to control the position of the rear water-cooled copper plate 10b to the rear controller so that the height A2 and the height B2 match. It may be sent to 56b.

As described above, in the second embodiment of the third embodiment, the positions of the front coil 30 and the rear coil 40 are aligned with each other in the height direction of the molten slag 6 and the molten pool 7. As a result, the violence of the molten slag 6 due to excitation can be suppressed, so that the bead shape can be stabilized and inclusions and the like can be prevented from being mixed.

1,1'... magnetic field application device, 2,3 ... base material, 4 ... groove, 5 ... welding wire, 6 ... molten slag, 7 ... molten pond, 8 ... interface, 9 ... welded part, 10,10a ... Front water-cooled copper plate, 11 ... Hole, 20, 10b ... Rear water-cooled copper plate, 21 ... Groove, 30 ... Front coil, 31, 41 ... Iron core, 40 ... Rear coil, 50, 50a ... Front vertical lift mechanism, 60, 50b ... Rear vertical lift mechanism, 54, 64, 54a, 54b ... Height sensor, 55, 65, 55a, 55b ... Reflector, 56, 56a ... Front controller, 66, 56b ... Rear controller, 90 ... Welding torch

Claims (18)

An electroslag welding method characterized in that electroslag welding of the base metal is performed while applying a magnetic field to a molten pool in the groove portion of the base metal. The electroslag welding method according to claim 1, wherein the magnetic field is a static magnetic field or a rotating magnetic field having a frequency of 1 Hz or less. The electroslag welding method according to claim 1, wherein the magnetic field is applied from the front side and the back side of the groove portion. The electroslag welding method according to claim 3, wherein the directions of the magnetic fields applied from the front side and the back side are the same. The electroslag welding method according to claim 3, wherein the directions of the magnetic fields applied from the front side and the back side are opposite to each other. Welding is performed by reciprocating the welding torch between the front side position and the back side position in the groove portion.
In the reciprocating motion of the welding torch, when the welding torch approaches the iron core of the magnetic field application coil on the front side to which the magnetic field is applied from the front side of the groove portion, the current value of the magnetic field application coil on the front side. To increase the current value of the magnetic field application coil on the back side to which the magnetic field is applied from the back side of the groove portion.
In the reciprocating movement of the welding torch, when the welding torch approaches the iron core of the magnetic field application coil on the back side, the current value of the magnetic field application coil on the back side is reduced, and the magnetic field application coil on the front side is used. The electroslag welding method according to claim 3, wherein the current value is increased. When the welding torch comes closest to the iron core of the magnetic field application coil on the front side, the current value of the magnetic field application coil on the front side is minimized, and the current value of the magnetic field application coil on the back side is maximized.
When the welding torch comes closest to the iron core of the magnetic field application coil on the back side, the current value of the magnetic field application coil on the back side is minimized, and the current value of the magnetic field application coil on the front side is maximized. The electroslag welding method according to claim 6. The electroslag welding method according to claim 6, wherein the direction of the current flowing through the magnetic field application coil on the front side and the magnetic field application coil on the back side is reversed for each cycle of the reciprocating motion of the welding torch. When the welding torch is closest to the iron core of the front side magnetic field application coil or the back side magnetic field application coil and is stationary, the current of the front side magnetic field application coil and the current of the back side magnetic field application coil The electroslag welding method according to claim 6, wherein the values are the same and the directions are reversed. The electroslag welding method according to claim 3, wherein the front side and the back side are opposite sides of the base material of the cooling copper plate arranged on the front surface and the back surface of the groove portion. At least one of the front side cooling copper plate arranged on the surface of the groove portion and the back side cooling copper plate arranged on the back surface is fixed to the base material.
The height of the central axis of the front side electromagnet arranged on the front side cooling copper plate from the reference surface and the height of the center axis of the back side electromagnet arranged on the back side cooling copper plate from the reference surface match. The electroslag welding method according to claim 10, wherein the electromagnet on the front side and the electromagnet on the back side are welded while moving. The electroslag welding method according to claim 11, wherein one of the front side cooling copper plate and the back side cooling copper plate is movable in a direction in which the groove portion extends. Both the front side cooling copper plate arranged on the surface of the groove portion and the back side cooling copper plate arranged on the back surface can move in the direction in which the groove portion extends.
The height of the central axis of the front side electromagnet arranged on the front side cooling copper plate from the reference surface and the height of the center axis of the back side electromagnet arranged on the back side cooling copper plate from the reference surface match. The electroslag welding method according to claim 10, wherein the front side cooling copper plate and the back side cooling copper plate are welded while moving. It is characterized in that an electromagnet for applying a magnetic field to the molten pool in the groove is arranged on the opposite side of the cooling copper plate arranged on the front surface and the back surface of the groove of the base material from the base material. Magnetic field application device in electroslag welding. The magnetic field application device in electroslag welding according to claim 14, wherein the cooling copper plate is provided with a hole or a groove, and the iron core of the electromagnet is fitted in the hole or the groove. A welding torch for welding while reciprocating between the front side position and the back side position in the groove portion is further arranged.
In the reciprocating motion of the welding torch, when the welding torch approaches the iron core of the electromagnet on the front side to which the magnetic field is applied from the front side of the groove portion, the current value of the electromagnet on the front side is reduced. The current value of the electromagnet on the back side to which the magnetic field is applied is increased from the back side of the groove portion.
In the reciprocating motion of the welding torch, when the welding torch approaches the iron core of the electromagnet on the back side, the current value of the electromagnet on the back side is decreased and the current value of the electromagnet on the front side is increased. The magnetic current application device in electroslag welding according to claim 14. At least one of the front side cooling copper plate arranged on the surface of the groove portion and the back side cooling copper plate arranged on the back surface is fixed to the base material.
The height of the central axis of the front side electromagnets arranged on the front side cooling copper plate from the reference surface matches the height of the center axis of the back side electromagnets arranged on the back side cooling copper plate from the reference surface. The magnetic field application device in electroslag welding according to claim 14, wherein the electromagnet on the front side and the electromagnet on the back side are configured to be movable. Both the front-side cooling copper plate arranged on the front surface of the groove portion and the back-side cooling copper plate arranged on the back surface have a structure that can be moved in the direction in which the groove portion extends.
The height of the central axis of the front side electromagnets arranged on the front side cooling copper plate from the reference surface and the height of the center axis of the back side electromagnets arranged on the back side cooling copper plate from the reference surface match. The magnetic field application device in electroslag welding according to claim 14, wherein the front side cooling copper plate and the back side cooling copper plate are configured to be movable.