JP2022013693A - Electroslag welding method and magnetic field application device in electroslag welding - Google Patents

Abstract

To apply a magnetic field to a molten pool in electroslag welding.SOLUTION: According to an electroslag welding method, electroslag welding of a base material is performed while applying a magnetic field into a groove by using a front upper side magnetic pole and a front lower side magnetic pole which are two upper and lower magnetic field application magnetic poles which are located on a front side of the groove of the base material, and a rear upper side magnetic pole and a rear lower side magnetic pole which are two upper and lower magnetic field application magnetic poles which are located on a rear side of the groove so that the magnetic field at the tip of the weld wire becomes weaker than the magnetic field at the molten pool in the groove.SELECTED DRAWING: Figure 6

Description

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

In arc welding, a magnetic stirring welding method in which a magnetic field is applied to a molten pool 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, a magnetic coil is 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 weld 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 so that molten slag and molten metal do not spill. 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, the molten slag is present, so that not only is it impossible to apply an effective magnetic field to the molten pool, but the space at the groove is narrow in the first place. , The coil cannot be placed either.

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 is arranged on the front side magnetic pole and the front lower side magnetic pole, which are two upper and lower magnetic field application magnetic poles arranged on the front side of the groove portion of the base metal, and on the back side of the groove portion. Using the two upper and lower magnetic field application magnetic fields, the back upper magnetic field and the back lower magnetic field, the magnetic field in the groove is weakened so that the magnetic field at the tip of the welding wire is weaker than the magnetic field in the molten pool in the groove. Provided is an electroslag welding method for performing electroslag welding of a base material while applying a magnet.

In the electroslag welding method, the front upper pole and the back upper pole are located at the same height, the front lower pole and the back lower pole are located at the same height, and the tip of the welding wire is located at the same height. It may be arranged so as to be located at a height between the height and the height of the lower front pole.

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 has the front side magnetic pole. And when approaching the lower front magnetic pole, the generated magnetic field of the upper front magnetic pole and the lower front magnetic pole is decreased, the generated magnetic field of the upper back magnetic pole and the lower back magnetic pole is increased, and in the reciprocating motion of the welding torch, When the welding torch approaches the back upper magnetic pole and the back lower magnetic pole, the generated magnetic field of the back upper magnetic pole and the back lower magnetic pole is reduced, and the generated magnetic field of the front upper magnetic pole and the front lower magnetic pole is increased. It may be there. In that case, the electroslag welding method maximizes the magnetic field generated by the back upper magnetic pole and the back lower magnetic pole when the welding torch is closest to the front upper magnetic pole and the front lower magnetic pole in the reciprocating motion of the welding torch. When the welding torch is closest to the back upper magnetic pole and the back lower magnetic pole in the reciprocating motion of the welding torch, the generated magnetic fields of the front upper magnetic pole and the front lower magnetic pole are maximized. good. Further, in the electroslag welding method, when the welding torch is located on the front side of the center in the thickness direction of the groove portion in the reciprocating motion of the welding torch, the generated magnetic fields of the back upper magnetic pole and the back lower magnetic pole are generated. Maximum, in the reciprocating motion of the welding torch, when the welding torch is located behind the center in the thickness direction of the groove, the generated magnetic field of the front upper magnetic pole and the front lower magnetic pole is maximized. May be.

The electroslag welding method balances the strength of the generated magnetic field of the front upper magnetic pole with the strength of the generated magnetic field of the front lower magnetic pole and the generation of the back upper magnetic pole so that the strength of the magnetic field at the tip of the welding wire is minimized. It may adjust at least one of the balance between the strength of the magnetic field and the strength of the generated magnetic field of the lower back magnetic pole.

In the electroslag welding method, a front side member made of a soft magnetic material is placed between the front upper magnetic pole and the front lower side magnetic pole, and a back side member made of a soft magnetic material is placed between the back upper magnetic pole and the back lower side magnetic pole. It may be something. In that case, the soft magnetic material may be any of iron, nickel, magnetic stainless steel, permalloy, permendur, and silicon steel. Alternatively, in the electroslag welding method, the front side member is arranged so that the lower end of the front side member is higher than the upper end of the molten pool, and the back side member is arranged so that the lower end of the back side member is higher than the upper end of the molten pool. It may be something.

Further, in the present invention, two upper and lower magnetic field application magnetic poles arranged on the front side of the groove portion of the base material, the upper front magnetic pole and the lower front magnetic pole, and two upper and lower magnetic poles arranged on the back side of the groove portion. It is equipped with a magnetic field application magnetic pole, a back upper magnetic pole and a back lower magnetic pole, and the front upper magnetic pole and the back upper magnetic pole are located at the same height, and the front lower magnetic pole and the back lower magnetic pole are located at the same height. Also provided is a magnetic field application device in electroslag welding in which the tip of the weld wire is located at a height between the height of the front top magnetic pole and the height of the front bottom magnetic pole.

The magnetic field application device in electroslag welding may be configured such that the magnetic field at the tip of the weld wire is weaker than the magnetic field at the molten pool in the groove.

At least one of the front upper pole, the front lower pole, the back upper pole, and the back lower pole may be configured so that the strength of the generated magnetic field can be adjusted.

The front upper pole and the front lower pole may share a coil, and the back upper pole and the back lower pole may share a coil.

In the magnetic field application device in electroslag welding, a front side member made of a soft magnetic material is arranged between the front upper magnetic pole and the front lower side magnetic pole, and the front side member is made of a soft magnetic material material between the back upper magnetic pole and the back lower side magnetic pole. The back side member may be arranged. In that case, the soft magnetic material may be any of iron, nickel, magnetic stainless steel, permalloy, permendur, and silicon steel. Alternatively, in the magnetic field application device in electroslag welding, the front side member is arranged so that the lower end of the front side member is higher than the upper end of the molten pool, and the lower end of the back side member is located higher than the upper end of the molten pool on the back side. The member may be arranged.

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

(A) and (b) are perspective views when the magnetic field application device in the conventional embodiment is viewed from the front side. (A) and (b) are perspective views when the magnetic field application device in the conventional embodiment is 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 the conventional embodiment. (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 upper coil, the front side lower coil, the rear side upper coil, and the rear side lower coil in the magnetic field application device of 1st Embodiment of this invention. It is a contour diagram which shows the magnetic field strength distribution in a molten slag, a molten pool, and a weld part in the magnetic field application device of 1st Embodiment of this invention. It is a contour diagram which shows the magnetic field strength distribution in the molten slag, the molten pool, and the weld part in the magnetic field application device of the conventional embodiment. It is a graph which compared the magnetic field strength distribution in the vertical direction of the central part in the thickness direction of a base metal between this embodiment and the conventional embodiment. (A) and (b) are diagrams showing changes in the flow of molten slag due to the application of a magnetic field. (A) and (b) are graphs for explaining changes in currents of the front coil and the rear coil in the magnetic field applying device of the second embodiment of the present invention. (A) and (b) are graphs for explaining changes in currents of the front coil and the rear coil in the magnetic field applying device according to the third embodiment of the present invention. FIG. 3 is a contour diagram showing a magnetic field strength distribution when the welding torch is at position B in the third embodiment of the present invention. FIG. 3 is a contour diagram showing a magnetic field strength distribution when the welding torch is at position C in the third embodiment of the present invention. FIG. 3 is a contour diagram showing a magnetic field strength distribution when the welding torch is at position F in the third embodiment of the present invention. It is a graph which showed the magnetic field distribution in the anteroposterior direction of the groove part when the welding torch is in the position B in the 3rd Embodiment of this invention. It is a graph which showed the magnetic field distribution in the anteroposterior direction of the groove part when the welding torch is in the position C in the 3rd Embodiment of this invention. It is a graph which showed the magnetic field distribution in the anteroposterior direction of the groove part when the welding torch is in the position F in the 3rd Embodiment of this invention. It is a figure which showed the position of the coil of the magnetic field application device in 5th Embodiment of this invention. It is a figure which showed the structural example of the magnetic field application device in 6th Embodiment of this invention. It is a graph which showed the magnetic flux density distribution when the front side magnetic body piece and the rear side magnetic body piece are arranged in the 6th Embodiment of this invention.

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

[Background of invention]
In electroslag welding, since the molten pool is located under the molten slag having a thickness of 10 to 30 mm, it is difficult to install a coil that generates a magnetic field for electromagnetic agitation in the vicinity of the molten pool as in arc welding. .. In order to solve this problem, the present inventors provide holes or grooves having a depth that does not penetrate each of the water-cooled copper plates installed before and after the welded portion, and fit the iron core of the coil into the holes or grooves. Hereinafter, "conventional embodiment") was considered.

1 (a) and 1 (b) are perspective views when the magnetic field application device 100 in the conventional embodiment is viewed from the front side (also referred to as the front side), and FIGS. 2 (a) and 2 (b) are conventional views. It is a perspective view of the magnetic field application device 100 in the embodiment seen from the rear side (also referred to as the back side).

As shown in FIGS. 1 (a) and 1 (b) and FIGS. 2 (a) and 2 (b), the magnetic field applying device 100 in the conventional embodiment includes a welding wire 5, a front water-cooled copper plate 10, and a rear water-cooled device 100. It includes a copper plate 20, a front coil 30, and a rear coil 40.

The welding wire 5 is inserted into the groove portion 4 formed in the butt 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), 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 inlet (not shown) for flowing in cooling water for water cooling and an outlet (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 inlet (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 rear 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 100 before fitting the front coil 30, and FIG. 1B is a perspective view of the magnetic field applying device 100 after fitting the front coil 30. be. 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 thereof. 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 100 before the rear coil 40 is fitted, and FIG. 2 (b) is a perspective view of the magnetic field applying device 100 after the rear coil 40 is fitted. 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.

Next, the arrangement of the front coil 30 and the rear coil 40 in the magnetic field applying device 100 of the conventional 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 100. In this embodiment, the specifications of the front coil 30 and the rear coil 40 are set as shown in Table 1 below.

That is, as shown in FIG. 3, the iron core 31 of the front coil 30 and the iron core 41 of the rear coil 40 are positioned 20 mm below the interface between the molten slag 6 and the molten pool 7. It is arranged so as to be. Further, as shown in Table 1, 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.

As a result, the iron core 31 of the front coil 30 and the iron core 41 of the rear coil 40 can be arranged in the vicinity of the molten pool 7, and a magnetic field having an effective strength can be applied to the molten pool 7.

By the way, according to this conventional embodiment, the molten pool 7 can be electromagnetically agitated, but not only the molten pool 7 but also the molten slag 6 is greatly drifted and electromagnetically agitated by the action of the magnetic field. This causes a problem that the mechanical strength of the welded portion 8 deteriorates due to the molten slag 6 being caught in the molten pool 7.

Further, in electric slag welding, the welding torch 9 is slid in the front-rear direction in order to weld evenly in the thickness direction of the thick plate to be welded. Therefore, when the welding torch 9 comes near the iron core 31 of the front coil 30 or the iron core 41 of the rear coil 40, a large Lorentz force acts on the molten pool 7 and the molten slag 6, and the molten slag 6 is strongly biased. It will be flowed and electromagnetically agitated. As a result, in addition to the problem that the mechanical strength of the welded portion 8 deteriorates due to the molten slag 6 being caught in the molten pool 7, the uneven flow of the molten slag 6 causes a bias in the penetration of the base materials 2 and 3. Problems also arise.

Hereinafter, embodiments for solving such problems will be described.

[First Embodiment]
First, the configuration of the magnetic field application device 200 according to the present embodiment will be described. 4 (a) and 4 (b) are perspective views when the magnetic field applying device 200 in the present embodiment is viewed from the front side (also referred to as the front side), and FIGS. 5 (a) and 5 (b) are the present implementation. It is a perspective view of the magnetic field application device 200 in the form of the above when viewed from the rear side (also referred to as the back side).

As shown in FIGS. 4 (a) and 4 (b) and FIGS. 5 (a) and 5 (b), the magnetic field applying device 200 in the present embodiment includes a welding wire 5, a front water-cooled copper plate 10, and a rear water-cooled copper plate. 20, the front upper coil 30a, the front lower coil 30b, the rear upper coil 40a, and the rear lower coil 40b. As described above, in the present embodiment, unlike the conventional embodiment, two coils are arranged vertically on the front water-cooled copper plate 10 and two coils are arranged vertically on the rear water-cooled copper plate 20.

The welding wire 5 is inserted into the groove portion 4 formed in the butt portion of the base materials 2 and 3. Then, it is supplied to the molten slag 6 (see FIG. 6) in the groove 4 in a state of being energized by a welding power source (not shown), 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. 6).

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 inlet (not shown) for flowing in cooling water for water cooling and an outlet (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 inlet (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 upper coil 30a is the upper magnetic coil of the two magnetic coils arranged on the front water-cooled copper plate 10, and the front lower coil 30b is the lower of the two magnetic coils arranged on the front water-cooled copper plate 10. It is a magnetic coil. Further, the rear upper coil 40a is the upper magnetic coil of the two magnetic coils arranged on the rear water-cooled copper plate 20, and the rear lower coil 40b is the two magnetisms arranged on the rear water-cooled copper plate 20. The lower magnetic coil of the coils. The front upper coil 30a, the front lower coil 30b, the rear upper coil 40a, and the rear lower coil 40b are each energized by a coil power supply (not shown) to generate a magnetic field, and the magnetic field is generated. It is applied to the molten pool 7 (see FIG. 6). In the following, the front upper coil 30a and the front lower coil 30b may be collectively referred to as a "front coil", and the rear upper coil 40a and the rear lower coil 40b may be collectively referred to as a "rear coil". Further, the front upper coil 30a and the rear upper coil 40a may be collectively referred to as an "upper coil", and the front lower coil 30b and the rear lower coil 40b may be collectively referred to as a "lower coil". Further, the front upper coil 30a, the front lower coil 30b, the rear upper coil 40a, and the rear lower coil 40b may be collectively referred to as "coils".

Here, FIG. 4A is a perspective view of the magnetic field application device 200 before fitting the front upper coil 30a and the front lower coil 30b, and FIG. 4B shows the front upper coil 30a and the front lower coil 30b. It is a perspective view of the magnetic field application device 200 after fitting. When the front water-cooled copper plate 10 moves upward according to the progress of welding, the front upper coil 30a and the front lower coil 30b also need to move upward. Therefore, as shown in the figure, the front water-cooled copper plate 10 has a hole 11a. , 11b are provided, and the iron core 31a of the front upper coil 30a and the iron core 31b of the front lower coil 30b are fitted in the holes 11a and 11b, respectively.

Further, FIG. 5A is a perspective view of the magnetic field application device 200 before fitting the rear upper coil 40a and the rear lower coil 40b, and FIG. 5B is a rear upper coil 40a and the rear lower coil 40a. It is a perspective view of the magnetic field application device 200 after fitting a coil 40b. 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 41a and the rear of the rear upper coil 40a are provided. The iron core 41b of the lower coil 40b is adapted to move upward as the welding progresses while being fitted in the groove 21.

In this embodiment, as shown in FIGS. 4 (a) and 4 (b) and FIGS. 5 (a) and 5 (b), the front upper coil 30a and the front lower coil 30b are arranged on the front side of the groove portion 4. The rear upper coil 40a and the rear lower coil 40b are 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 positions of the front upper coil 30a and the front lower coil 30b are on the opposite sides of the base materials 2 and 3 of the front water-cooled copper plate 10, and the arrangement positions of the rear upper coil 40a and the rear lower coil 40b are. It can be said that the rear side water-cooled copper plate 20 is on the opposite side to the base materials 2 and 3.

Further, in the present embodiment, as shown in FIGS. 4 (a) and 4 (b) and FIGS. 5 (a) and 5 (b), the rear lower coil is on the plane of the center of the base materials 2 and 3 in the thickness direction. The origin is a point at the height of 40b and at the center of the groove portion 4 in the width direction. Then, the direction toward the right side when viewed from the front side of the base materials 2 and 3 in the direction perpendicular to the welding progress direction from the origin on the plane of the center in the thickness direction of the base materials 2 and 3 is defined as the positive direction of the X axis. .. Further, the direction from the origin to the rear side of the base materials 2 and 3 in the direction perpendicular to the central plane in the thickness direction of the base materials 2 and 3 is defined as the positive direction of the Y axis. Further, the direction from the origin to the welding progress direction on the plane of the center in the thickness direction of the base materials 2 and 3 is defined as the positive direction of the Z axis.

Next, the arrangement of the front upper coil 30a, the front lower coil 30b, the rear upper coil 40a, and the rear lower coil 40b in the magnetic field applying device 200 of the present embodiment will be described. FIG. 6 is a diagram showing the positions of the coils 30a, 30b, 40a, and 40b in the magnetic field applying device 200. In the present embodiment, as shown in the figure, the vertical positions of the iron core 31b of the front upper coil 30a and the iron core 41a of the rear upper coil 40a are set to be the same, and the iron core 31b and the rear side of the front lower coil 30b are set to be the same. The vertical position of the iron core 41b of the lower coil 40b is set to be the same. That is, the magnetic poles of the front upper coil 30a and the magnetic poles of the rear upper coil 40a are set to the same height, and the magnetic poles of the front lower coil 30b and the rear lower coil 40b are set to the same height. Here, the magnetic pole of the front upper coil 30a is an example of the front upper magnetic pole, the magnetic pole of the rear upper coil 40a is an example of the back upper magnetic pole, and the magnetic pole of the front lower coil 30b is an example of the front lower magnetic pole. The magnetic pole of the rear lower coil 40b is an example of the back lower magnetic pole.

Then, a current is passed through the front lower coil 30b and the rear lower coil 40b so that a magnetic field is generated from the magnetic pole of the front lower coil 30b toward the magnetic pole of the rear lower coil 40b. Then, a current is passed through the rear upper coil 40a and the front upper coil 30a so that a magnetic field is generated from the magnetic pole of the rear upper coil 40a toward the magnetic pole of the front upper coil 30a. In the figure, the white arrow indicates the direction of the magnetic field. Here, it is assumed that the currents of the coils 30a, 30b, 40a, and 40b are set so that the absolute values of the magnetic forces generated from the magnetic poles of the coils 30a, 30b, 40a, and 40b are the same. Then, the magnetic field in the central portion surrounded by the magnetic poles of the coils 30a, 30b, 40a, and 40b is canceled by the magnetic field generated by the magnetic poles of the coils 30a, 30b, 40a, and 40b, and becomes almost zero.

In the coil arrangement shown in FIG. 6, it is assumed that the molten slag 6, the molten pool 7, and the welded portion 8 are located in the region surrounded by the coils 30a, 30b, 40a, and 40b. Here, it is assumed that the coils 30a, 30b, 40a, 40b satisfy the conditions shown in Table 2 below.

FIG. 7 is a contour diagram showing the magnetic field strength distribution in the molten slag 6, the molten pool 7, and the welded portion 8 in this case. In the figure, the white arrow indicates the direction of the magnetic field. In this figure, the magnetic field strength is small at the center of the upper coils 30a and 40a and the lower coils 30b and 40b, as indicated by the white circles.

On the other hand, in the conventional embodiment, the front coil 30 and the rear coil 40 are arranged on the front side and the rear side of the groove portion 4, respectively. FIG. 8 is a contour diagram showing the magnetic field strength distribution in the molten slag 6, the molten pool 7, and the welded portion 8 in this case. In the figure, the white arrow indicates the direction of the magnetic field. In this figure, the magnetic field strength is small in the vertical position of the front coil 30 and the rear coil 40, as indicated by white circles.

FIG. 9 is a graph showing the magnetic field strength distribution in the vertical direction of the central portion in the thickness direction of the base materials 2 and 3 in comparison between the present embodiment and the conventional embodiment. Here, the central portion of the base materials 2 and 3 in the thickness direction is the central portion of the front upper coil 30a and the rear upper coil 40a (the front lower coil 30b and the rear lower coil 40b) in the present embodiment. Same as the central part) and the same part in the front-back direction. On the other hand, the central portion of the base materials 2 and 3 in the thickness direction is a portion in which the positions of the front coil 30 and the rear coil 40 are the same as those of the central portion in the front-rear direction in the conventional embodiment. Further, in FIG. 9, the vertical position 0 mm is the same as the vertical position of the center of the iron core 31b of the front lower coil 30b (the same as the vertical position of the center of the iron core 41b of the rear lower coil 40b) in the present embodiment. ) Is set. On the other hand, in FIG. 9, the vertical position 0 mm is the vertical position of the center of the iron core 31 of the front coil 30 (the same as the vertical position of the center of the iron core 41 of the rear coil 40) in the conventional embodiment. Is set to.

From the graph of FIG. 9, in the present embodiment, the magnetic field strength is substantially equal to the central portion (vertical position 30 mm) of the upper coils 30a and 40a and the lower coils 30b and 40b, as indicated by black circles on the solid line graph. It turns out to be zero. It can also be seen that the maximum values are obtained at the vertical positions of 0 mm and 60 mm.

On the other hand, from the graph of FIG. 9, in the conventional embodiment, the magnetic field strength becomes maximum at the vertical position 0 mm and decreases as the vertical position increases, but as shown by the black circles on the broken line graph, It can be seen that there is about 30 mT at a vertical position of 30 mm.

That is, it can be seen that in the present embodiment, the magnetic field is weaker in the vertical position range of 16 mm to 34 mm than in the conventional embodiment.

Here, it returns to FIG. FIG. 6 shows an example of the positional relationship between the magnetic poles of the coils 30a, 30b, 40a, and 40b, the welding wire 5, the molten slag 6, the molten pool 7, and the welding torch 9. In the present embodiment, the magnetic poles and the lower of the upper coils 30a and 40a are set so that the midpoint between the magnetic poles of the upper coils 30a and 40a and the magnetic poles of the lower coils 30b and 40b is the same as the height of the tip of the welding wire 5. The magnetic poles of the coils 30b and 40b are arranged. This arrangement is an example of arranging so that the tip of the welding wire 5 is located at a height between the height of the magnetic poles of the upper coils 30a and 40a and the height of the magnetic poles of the lower coils 30b and 40b. Is. In this embodiment, the magnetic poles of the upper coils 30a and 40a, the magnetic poles of the lower coils 30b and 40b, and the welding torch 9 are configured to move up and down integrally, and welding is performed to a position where the magnetic field strength is minimized. It is assumed that the tip of the wire 5 can be positioned accurately to some extent. By arranging the magnetic poles of the upper coils 30a and 40a and the magnetic poles of the lower coils 30b and 40b as described above, the point of zero magnetic field shown in FIGS. 7 and 9 is brought to the tip of the welding wire 5. Can be done. That is, the magnetic field at the tip of the welding wire 5 can be weaker than the magnetic field at the molten pool 7.

It is known that the tip of the welding wire 5 is the hottest region in the molten slag 6 and has the highest current density. When a magnetic field is applied to this region, the flow of the molten slag 6 tends to be biased due to the Lorentz force, but in the present embodiment, the magnetic field at the tip of the welding wire 5 becomes almost zero, so that the coil magnetic field to the flow of the molten slag 6 The effect of is minor. On the other hand, since the magnetic field equivalent to that in the conventional embodiment is applied to the molten pool 7, particularly near the bottom of the molten pool 7, which is originally desired to be agitated, the stirring effect is not impaired.

In FIG. 6, the directions of the magnetic poles of the front upper coil 30a and the rear upper coil 40a are the same, and the directions of the magnetic poles of the front lower coil 30b and the rear lower coil 40b are the same. The directions of the magnetic poles of the front upper coil 30a and the front lower coil 30b are opposite, and the directions of the magnetic poles of the rear upper coil 40a and the rear lower coil 40b are opposite. In order to weaken the magnetic field strength at the position of the tip of the welding wire 5, it is essential to have such a magnetic pole orientation.

10 (a) and 10 (b) are diagrams showing changes in the flow of the molten slag 6 due to the application of a magnetic field. As shown in FIG. 10A, usually, a pinch force acts on the molten slag 6 due to a welding current, and a downward flow S is generated around the welding wire 5. This flow S is bent in the left-right direction according to the direction of the Lorentz force due to the action of the magnetic field applied for electromagnetic stirring. In FIG. 10B, since the magnetic field M in the depth direction of the paper surface is applied, the Lorentz force L acts in the right direction, whereby the flow S curves in the right direction. As a result, temperature unevenness occurs in the molten slag 6 in the left-right direction, and a difference occurs in the amount of penetration of the base materials 2 and 3.

According to the coil arrangement in the present embodiment, the magnetic field directly under the welding wire 5 in the molten slag 6 is canceled and minimized by the magnetic fields generated by the magnetic poles of the upper coils 30a and 40a and the magnetic poles of the lower coils 30b and 40b. Will be done. As a result, the drift and stirring of the molten slag 6 are reduced, and the bias of the melted shape of the base materials 2 and 3 and the entrainment of the molten slag 6 are reduced.

Further, according to the present embodiment, a strong magnetic field acts on the molten pool 7 near the magnetic poles of the upper coils 30a and 40a or the lower coils 30b and 40b to agitate the molten metal. As a result, the metal structure becomes finer and inclusions in the metal are reduced, so that the mechanical properties of the welded portion 8 are improved.

[Second Embodiment]
In the first embodiment, since the magnetic field strength of the central portion of the groove portion 4 in the front-rear direction becomes almost zero, the tip portion of the welding wire 5 is located at the center portion of the groove portion 4 in the front-rear direction. It is effective in preventing the drift of the molten slag 6. However, when the welding torch 9 approaches the side of the coil that generates the magnetic field from the central portion, the tip portion of the welding wire 5 deviates from the region where the magnetic field strength is zero, and the flow of the molten slag 6 is easily affected by the magnetic field.

Therefore, in the present embodiment, when the welding torch 9 approaches the front side from the central portion of the groove portion 4, the currents of the front side upper coil 30a and the front side lower coil 30b are reduced. That is, when the welding torch 9 approaches the magnetic poles of the front upper coil 30a and the magnetic poles of the front lower coil 30b, the generated magnetic fields of the magnetic poles of the front upper coil 30a and the front lower coil 30b are reduced. At this time, the currents of the rear upper coil 40a and the rear lower coil 40b are maintained or increased. That is, the generated magnetic fields of the magnetic poles of the rear upper coil 40a and the magnetic poles of the rear lower coil 40b are maintained or increased.

Further, in the present embodiment, conversely, when the welding torch 9 approaches the rear side from the central portion of the groove portion 4, the currents of the rear side upper coil 40a and the rear side lower coil 40b are reduced. That is, when the welding torch 9 approaches the magnetic poles of the rear upper coil 40a and the magnetic poles of the rear lower coil 40b, the generated magnetic fields of the magnetic poles of the rear upper coil 40a and the rear lower coil 40b are reduced. At this time, the currents of the front upper coil 30a and the front lower coil 30b are maintained or increased. That is, the generated magnetic fields of the magnetic poles of the front upper coil 30a and the magnetic poles of the front lower coil 30b are maintained or increased.

As described above, in the present embodiment, the current values of the front coil 30a and 30b and the rear coils 40a and 40b are changed according to the position of the welding torch 9. As a result, the region where the magnetic field strength becomes zero can be moved to the front side or the rear side of the groove portion 4, and even when the welding torch 9 slides, the influence of the magnetic field on the flow of the molten slag 6 can be suppressed. can.

11 (a) and 11 (b) are graphs for explaining changes in the currents of the front coils 30a and 30b and the rear coils 40a and 40b in this case.

As shown in FIG. 11A, the welding torch 9 periodically moves between the position B (rear side) and the position F (front side), and is temporarily stopped at the position F and the position B. ..

As shown by a thin line in FIG. 11B, the current flowing through the rear coils 40a and 40b is maximum when the welding torch 9 is at position F, decreases as the welding torch 9 moves to the rear, and is welded. It is the minimum (a quarter of the maximum value) when the torch 9 is at position B.

As shown by the thick line in FIG. 11B, the current flowing through the front coils 30a and 30b is maximum when the welding torch 9 is at position B, decreases as the welding torch 9 moves to the front side, and the welding torch 9 Is at the minimum (1/8 of the maximum value) when is at the position F.

Here, the minimum value of the current flowing through the rear coils 40a and 40b is larger than the minimum value of the current flowing through the front coils 30a and 30b because the width of the groove 4 is larger on the front side on the rear side. This is because it is narrower than the above and easily attenuates due to the influence of the base materials 2 and 3.

By passing an electric current through the front coils 30a and 30b and the rear coils 40a and 40b in the energization pattern as shown in FIGS. 11A and 11B, the rear coil 40a is when the position of the welding torch 9 is the rearmost. , The magnetic flux density acting on the welding current of the molten pool 7 can be increased as compared with the case where the current of 40b is set to zero. On the contrary, the same effect is obtained when the position of the welding torch 9 is the frontmost side.

In the present embodiment, the magnetic field of each magnetic pole is changed according to the sliding of the welding torch 9, that is, the movement of the tip of the welding wire 5 reciprocating between the front surface and the rear surface of the groove portion 4. I made it. As a result, even in electroslag welding in which the welding torch 9 is slid, the magnetic field at the tip of the welding wire 5 can always be minimized. As a result, the metal structure becomes finer and inclusions in the metal are reduced, so that the mechanical properties of the welded portion 8 are improved.

[Third Embodiment]
In this embodiment, the currents of the front coils 30a and 30b and the rear coils 40a and 40b are maximized when the welding torch 9 is located at the center of the groove portion 4.

12 (a) and 12 (b) are graphs for explaining changes in the currents of the front coils 30a and 30b and the rear coils 40a and 40b in this case.

As shown in FIG. 12A, the welding torch 9 periodically moves between the position B (rear side) and the position F (front side), and is temporarily stopped at the position F and the position B. ..

The current flowing through the rear coils 40a and 40b is maximum when the welding torch 9 is between the position F and the position C, and the welding torch 9 is rearward from the position C, as shown by a thin line in FIG. 12 (b). It decreases as it moves to the side, and is the minimum (1/4 of the maximum value) when the welding torch 9 is at position B.

As shown by the thick line in FIG. 12B, the current flowing through the front coils 30a and 30b is maximum when the welding torch 9 is between the position B and the position C, and the welding torch 9 moves from the position C to the front side. It decreases as it moves and is at its minimum (1/8 of the maximum) when the weld torch 9 is at position F.

13 to 15 are contour diagrams showing the magnetic field strength distribution when the welding torch 9 is at the position B, the position C, and the position F in the present embodiment, respectively. As shown in FIG. 13, when the welding torch 9 is located at the position B indicated by the vertical line of the broken line, that is, the position near the rear side, the region where the magnetic field is weak moves toward the rear side. Further, as shown in FIG. 14, when the welding torch 9 is located at the position C indicated by the vertical line of the broken line, that is, at a position close to the center, the region where the magnetic field is weak comes to the center. Further, as shown in FIG. 15, when the welding torch 9 is located at the position F indicated by the vertical line of the broken line, that is, at a position close to the front side, the region where the magnetic field is weak moves toward the front side.

16 to 18 are graphs showing the magnetic field distribution in the front-rear direction of the groove portion 4 when the welding torch 9 is at the position B, the position C, and the position F in the present embodiment, respectively. In these graphs, the left side corresponds to the rear side of the groove portion 4, and the right side corresponds to the front side of the groove portion 4. Further, the magnetic field strength when the vertical position is the center position of the lower coils 30b and 40b is shown by a thick line, and the vertical position is the position of the intermediate point between the upper coils 30a and 40a and the lower coils 30b and 40b. The magnetic field strength of is shown by a thin line. Here, although the magnetism of the base materials 2 and 3 is taken into consideration in the magnetic field calculation, it is assumed that the groove portion 4 to 5 mm is non-magnetic. From these graphs, the vertical positions are the upper coils 30a and 40a and the lower coils 30b and 40b regardless of whether the welding torch 9 is located at any of the positions B, C and F indicated by the vertical line of the broken line in each graph. It can be seen that the magnetic field strength at the position of the midpoint of is almost zero, while the magnetic field strength at the position of the center of the upper coils 30a and 40a in the vertical direction is at a constant level.

The Lorentz force that contributes to the stirring of molten metal is proportional to the magnitude of the magnetic force. On the other hand, the magnitude of the magnetic force decreases as the distance from the magnetic pole increases. In the present embodiment, the Lorentz force applied to the molten metal can be increased by maximizing the current at the intermediate point of sliding of the welding torch 9. As a result, the metal structure becomes finer and inclusions in the metal are reduced, so that the mechanical properties of the welded portion 8 are improved.

[Fourth Embodiment]
In the first to third embodiments, the current and magnetomotive force of the front upper coil 30a and the current and magnetomotive force of the front lower coil 30b are the same, and the current and magnetomotive force of the rear upper coil 40a and the rear lower coil are the same. The current and magnetomotive force of 40b were the same. In that case, the region where the magnetic field is canceled and becomes zero is the region of the intermediate point between the upper coils 30a and 40a and the lower coils 30b and 40b.

When the vertical position of the tip of the welding wire 5 is at the midpoint between the upper coils 30a and 40a and the lower coils 30b and 40b as shown in FIG. 6, the upper coils 30a and 40a and the lower coil 30b are thus located. It is desirable that the current and the magnetomotive force are the same at 40b and 40b. On the other hand, if the welding conditions change and the vertical position of the tip of the welding wire 5 is different from the position of the midpoint between the upper coils 30a and 40a and the lower coils 30b and 40b, the magnetic field at the tip of the welding wire 5 The strength does not become zero, and the flow of the molten slag 6 may be biased. In that case, it is advisable to make a difference between the current of the front upper coil 30a and the current of the front lower coil 30b, or make a difference between the current of the rear upper coil 40a and the current of the rear lower coil 40b. By doing so, the region where the magnetic field strength becomes zero is adjusted in the vertical direction from the position of the intermediate point between the upper coils 30a and 40a and the lower coils 30b and 40b.

In the present embodiment, at least one of the current balance between the front upper coil 30a and the front lower coil 30b and the current balance between the rear upper coil 40a and the rear lower coil 40b is adjusted. That is, at least one of the magnetic poles of the front upper coil 30a, the magnetic poles of the front lower coil 30b, the magnetic poles of the rear upper coil 40a, and the magnetic poles of the rear lower coil 40b is configured so that the strength of the generated magnetic field can be adjusted. And said. At least the balance of the strength of the generated magnetic field between the magnetic poles of the front upper coil 30a and the magnetic poles of the front lower coil 30b and the balance of the strength of the generated magnetic field between the magnetic poles of the rear upper coil 40a and the magnetic poles of the rear lower coil 40b. I tried to adjust either one. As a result, even if the positional relationship between the tip of the welding wire 5 and the front water-cooled copper plate 10 and the rear water-cooled copper plate 20 is deviated, the vertical position in the region where the magnetic field becomes zero can be adjusted.

[Fifth Embodiment]
The fifth embodiment is a modification of the shape of the coil in the magnetic field applying device 200 of the first to third embodiments. FIG. 19 is a diagram showing the positions of the coils of the magnetic field applying device 200 in the fifth embodiment.

In the first to third embodiments, the front upper coil 30a and the front lower coil 30b have the same magnetomotive force and the direction of the magnetic field is opposite, and the rear upper coil 40a and the rear lower coil 40b also have the same magnetomotive force. The direction of the magnetic field is opposite. Therefore, in the fifth embodiment, the magnetic poles of the front upper coil 30a and the magnetic poles of the front lower coil 30b are shared, and the magnetic poles of the rear upper coil 40a and the rear lower coil 40b are shared. That is, the front upper magnetic pole that was the magnetic pole of the front upper coil 30a and the front lower magnetic pole that was the magnetic pole of the front lower coil 30b are the front coil 30c that combines the front upper coil 30a and the front lower coil 30b. , And the iron core 31c, which is a collection of the iron core 31a and the iron core 31b. Further, the rear upper magnetic pole, which was the magnetic pole of the rear upper coil 40a, and the rear lower magnetic pole, which was the magnetic pole of the rear lower coil 40b, combined the rear upper coil 40a and the rear lower coil 40b. The rear coil 40c and the iron core 41c, which is a combination of the iron core 41a and the iron core 41b, are shared.

[Sixth Embodiment]
FIG. 20 is a diagram showing a configuration example of the magnetic field applying device 200 according to the sixth embodiment. As shown in the figure, the magnetic field application device 200 according to the present embodiment includes a front water-cooled copper plate 10, a rear water-cooled copper plate 20, a front upper coil 30a and its iron core 31a, and a front lower coil 30b and its iron core 31b. , The rear upper coil 40a and its iron core 41a, and the rear lower coil 40b and its iron core 41b. Further, in the region surrounded by the coils 30a, 30b, 40a, 40b, there are a welding wire 5, a molten slag 6, a molten pool 7, a welded portion 8, and a weld torch 9. Since these components are the same as those described in the first embodiment, the description thereof will be omitted. Further, the conditions of the coils 30a, 30b, 40a, and 40b are also the same as those shown in Table 2 in the first embodiment.

In the present embodiment, the molten pool 7 side of the iron core 31a of the front upper coil 30a (the magnetic pole on the molten pool 7 side of the front upper coil 30a) and the molten pool 7 side of the iron core 31b of the front lower coil 30b (front lower coil 30b). A front magnetic material piece 32 made of a soft magnetic material is arranged between the magnetic pole on the 7 side of the molten pool and the magnetic pole on the 7 side of the molten pool. Further, the molten pool 7 side of the iron core 41a of the rear upper coil 40a (the magnetic pole on the molten pool 7 side of the rear upper coil 40a) and the molten pool 7 side of the iron core 41b of the rear lower coil 40b (rear lower coil 40b). A rear magnetic material piece 42 made of a soft magnetic material is arranged between the magnetic pole on the 7 side of the molten pool and the magnetic pole on the 7 side of the molten pool. The size of the front magnetic material piece 32 and the rear magnetic material piece 42 is 30 mm in the vertical direction, 20 mm in the horizontal direction, and 5 mm in the front-rear direction. Here, the soft magnetic material is, for example, iron such as soft iron, nickel, magnetic stainless steel, permalloy, permendur, or silicon steel. The front magnetic material piece 32 is an example of a front side member made of a soft magnetic material, and the rear magnetic material piece 42 is an example of a back side member made of a soft magnetic material.

Further, the front-rear position of the surface of the front magnetic material piece 32 on the molten pool 7 side is the same as the front-rear position of the end portion of the iron cores 31a and 31b on the molten pool 7 side. The front-rear position of the surface of the rear magnetic material piece 42 on the molten pool 7 side is the same as the front-rear position of the end portion of the iron cores 41a and 41b on the molten pool 7 side.

Further, in the present embodiment, in order to fix the front magnetic material piece 32 between the iron cores 31a and 31b, a non-magnetic and heat-resistant aluminum spacer 33 is arranged. Further, in order to fix the rear magnetic material piece 42 between the iron cores 41a and 41b, a non-magnetic and heat-resistant aluminum spacer 43 is arranged.

The magnetic flux density distribution in the groove 4 when the front magnetic piece 32 and the rear magnetic piece 42 are not arranged is as shown in FIG. FIG. 17 can be generally regarded as a graph showing the magnetic flux density distribution when the current flowing through the front coils 30a and 30b and the current flowing through the rear coils 40a and 40b are equal. In FIG. 17, the magnetic flux density is reduced to approximately zero near the head of the weld wire 5, but deviates from zero when slightly displaced back and forth, and increases to about 60 mT near the front water-cooled copper plate 10 and the rear water-cooled copper plate 20. It has become. In order to further suppress the electromagnetic stirring effect on the molten slag 6, it is desirable to suppress the magnetic flux density in the region R surrounded by the broken line in FIG. 20 as much as possible.

FIG. 21 is a graph showing the magnetic flux density distribution when the front magnetic material piece 32 and the rear magnetic material piece 42 are arranged. In the figure, the solid line shows the magnetic flux density distribution in the state where the front magnetic material piece 32 and the rear magnetic material piece 42 are not arranged, and the broken line shows the magnetic flux in the state where the front magnetic material piece 32 and the rear magnetic material piece 42 are arranged. Shows the density distribution. Comparing the two, the magnetic flux density distribution at the center height (near the solidification interface) of the lower coils 30b and 40b in the groove portion 4 does not change significantly. On the other hand, the magnetic flux density distribution at the intermediate height (near the tip of the welding wire 5) between the upper coils 30a and 40a and the lower coils 30b and 40b is suppressed in the groove portion 4. In particular, it is suppressed to about one-fifth in the vicinity of the front water-cooled copper plate 10 and the rear water-cooled copper plate 20. Therefore, by arranging the front magnetic material piece 32 and the rear magnetic material piece 42, only the molten pool 7 can be selectively electromagnetically agitated.

More specifically, the magnetic fluxes in the vicinity of the front magnetic piece 32 and the rear magnetic piece 42 are absorbed by the front magnetic piece 32 and the rear magnetic piece 42, respectively, and have a relatively high current density in the molten slag 6. The magnetic field strength near the tip of the high welding wire 5 (region R in FIG. 20) is further suppressed. As a result, the electromagnetic stirring effect of the molten slag 6 can be further suppressed, and the entrainment of the molten slag 6 in the molten pool 7 and the left-right bias of the melting of the base materials 2 and 3 can be further suppressed.

As described above, the purpose of arranging the front magnetic piece 32 and the rear magnetic piece 42 is to suppress the magnetic flux density only in the vicinity of the tip of the welding wire 5 in the molten slag 6. Therefore, it is not preferable that the front magnetic material piece 32 and the rear magnetic material piece 42 are arranged at the same vertical position as the molten pool 7. This is because when the front magnetic material piece 32 and the rear magnetic material piece 42 are arranged at the same upper and lower positions as the molten pool 7, the magnetic flux density of the molten pool 7 is also suppressed. Therefore, the front magnetic piece 32 and the rear magnetic piece 42 are arranged at an intermediate point between the upper coils 30a and 40a and the lower coils 30b and 40b, and the lower ends of the front magnetic piece 32 and the rear magnetic piece 42 are arranged. It is desirable that the position is higher than the upper end of the molten pool 7.

2, 3 ... Base material, 4 ... Groove, 5 ... Welding wire, 6 ... Molten slag, 7 ... Molten pond, 8 ... Welding part, 9 ... Welding torch, 10 ... Front water-cooled copper plate, 11a, 11b ... Hole, 20 ... Rear water-cooled copper plate, 21 ... Groove, 30a ... Front upper coil, 30b ... Front lower coil, 30c ... Front coil, 31a, 31b, 31c ... Iron core, 32 ... Front magnetic piece, 33 ... Spacer, 40a ... Rear upper coil, 40b ... Rear lower coil, 40c ... Rear coil, 41a, 41b, 41c ... Iron core, 42 ... Rear magnetic material piece, 43 ... Spacer, 100, 200 ... Magnetic field application device

Claims (16)

Two upper and lower magnetic field application magnetic poles arranged on the front side of the groove portion of the base material, the upper front magnetic pole and the lower front magnetic pole, and two upper and lower magnetic field application magnetic poles arranged on the back side of the groove portion. Using the back upper magnetic pole and the back lower magnetic pole, the base material is applied while applying a magnetic field in the groove so that the magnetic field at the tip of the welding wire is weaker than the magnetic field in the molten pool in the groove. An electroslag welding method characterized by performing electroslag welding. The front upper magnetic pole and the back upper magnetic pole are located at the same height, the front lower magnetic pole and the back lower magnetic pole are located at the same height, and the tip of the weld wire is the front upper magnetic pole. The electroslag welding method according to claim 1, wherein the electroslag welding method is arranged so as to be located at a height between the height and the height of the lower magnetic pole of the table. The welding torch is welded while reciprocating 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 front upper magnetic pole and the front lower magnetic pole, the generated magnetic fields of the front upper magnetic pole and the front lower magnetic pole are reduced, and the back side of the welding torch is generated. Increasing the generated magnetic field of the upper magnetic pole and the back lower magnetic pole,
In the reciprocating motion of the welding torch, when the welding torch approaches the back upper magnetic pole and the back lower magnetic pole, the generated magnetic fields of the back upper magnetic pole and the back lower magnetic pole are reduced, and the front surface. The electroslag welding method according to claim 1, wherein the generated magnetic fields of the upper magnetic pole and the lower magnetic pole on the front surface are increased. In the reciprocating motion of the welding torch, when the welding torch is closest to the front upper magnetic pole and the front lower magnetic pole, the generated magnetic fields of the back upper magnetic pole and the back lower magnetic pole are maximized.
In the reciprocating motion of the welding torch, when the welding torch is closest to the back upper magnetic pole and the back lower magnetic pole, the generated magnetic fields of the front upper magnetic pole and the front lower magnetic pole are maximized. 3. The electroslag welding method according to claim 3. In the reciprocating motion of the welding torch, when the welding torch is located on the front side of the center in the thickness direction of the groove portion, the generated magnetic fields of the back upper magnetic pole and the back lower magnetic pole are maximized.
In the reciprocating motion of the welding torch, when the welding torch is located behind the center in the thickness direction of the groove portion, the generated magnetic fields of the front upper magnetic pole and the front lower magnetic pole are maximized. The electroslag welding method according to claim 4, wherein the method is characterized by the above. The balance between the strength of the generated magnetic field of the front upper magnetic pole and the strength of the generated magnetic field of the front lower magnetic pole, and the generated magnetic field of the back upper magnetic pole so that the strength of the magnetic field at the tip of the welding wire is minimized. The electroslag welding method according to claim 1, wherein at least one of the balance between the strength and the strength of the generated magnetic field of the lower back magnetic pole is adjusted. A front side member made of a soft magnetic material is arranged between the front upper magnetic pole and the front lower side magnetic pole, and a back side member made of a soft magnetic material is arranged between the back upper magnetic pole and the back lower side magnetic pole. The electroslag welding method according to claim 1. The electroslag welding method according to claim 7, wherein the soft magnetic material is any one of iron, nickel, magnetic stainless steel, permalloy, permendur, and silicon steel. The front side member is arranged so that the lower end of the front side member is higher than the upper end of the molten pool, and the back side member is arranged so that the lower end of the back side member is higher than the upper end of the molten pool. 7. The electroslag welding method according to claim 7. The upper and lower magnetic poles, which are the two magnetic field application magnetic poles above and below, arranged on the front side of the groove of the base metal, and the front and lower magnetic poles,
It is provided with two upper and lower magnetic field application magnetic poles, a back upper magnetic pole and a back lower magnetic pole, which are arranged on the back side of the groove portion.
The front upper magnetic pole and the back upper magnetic pole are located at the same height, the front lower magnetic pole and the back lower magnetic pole are located at the same height, and the tip of the welding wire is the height of the front upper magnetic pole. A magnetic field application device in electroslag welding, characterized in that it is located at a height between the height of the lower magnetic pole and the height of the lower magnetic pole. The magnetic field application device in electroslag welding according to claim 10, wherein the magnetic field at the tip of the welding wire is configured to be weaker than the magnetic field at the molten pool in the groove. The tenth aspect of the present invention, wherein at least one of the front upper magnetic pole, the front lower magnetic pole, the back upper magnetic pole, and the back lower magnetic pole is configured so that the strength of the generated magnetic field can be adjusted. Magnetic field application device in electroslag welding. The magnetic field application device in electroslag welding according to claim 10, wherein the front upper magnetic pole and the front lower magnetic pole share a coil, and the back upper magnetic pole and the back lower magnetic pole share a coil. A front side member made of a soft magnetic material is arranged between the front upper side magnetic pole and the front side lower side magnetic pole.
The magnetic field application device in electroslag welding according to claim 10, wherein a back side member made of a soft magnetic material is arranged between the back upper magnetic pole and the back lower magnetic pole. The magnetic field application device in electroslag welding according to claim 14, wherein the soft magnetic material is any one of iron, nickel, magnetic stainless steel, permalloy, permendur, and silicon steel. The front side member is arranged so that the lower end of the front side member is higher than the upper end of the molten pool, and the back side member is arranged so that the lower end of the back side member is higher than the upper end of the molten pool. The magnetic field application device in electroslag welding according to claim 14.

Images