JP5621961B2 - Submerged arc welding method and apparatus - Google Patents

Description

  The present invention relates to a submerged arc welding method and apparatus, and more particularly to a submerged arc welding method and apparatus using multiple electrodes.

  Submerged arc welding is frequently used in the manufacture of large-sized welded structures (for example, ships, bridges, boilers, pressure vessels, etc.). In submerged arc welding, an arc is generated between the tip of the wire wound in a coil shape and the base material, and the wire is fed in the welding direction while keeping the arc length constant, In this welding method, welding is performed while covering a molten pool formed by an arc with a flux. Such submerged arc welding can apply a large current because a large-diameter wire can be applied, and the welding speed is large and efficient. Since the arc is generated in the flux, the heat efficiency is high. Can be increased, and there is an advantage that it is not necessary to shield light.

  Further, in submerged arc welding, high efficiency is achieved by narrowing the groove and increasing the number of electrodes (see, for example, Non-Patent Document 1, Patent Document 1, and Patent Document 2). The number of passes of the weld layer can be reduced by narrowing the groove, and the welding speed can be improved by using multiple electrodes.

  Non-Patent Document 1 discusses various narrow groove welding methods for reducing the number of welding passes by narrowing the groove cross-sectional area of welded joints for the purpose of improving the efficiency of welding work in thick plate welding. It has been described that narrow groove welding can be applied to submerged arc welding since a good flux was developed.

  Further, in Patent Document 1, when welding a narrow groove having a groove width of 10 to 25 mm and a groove angle of 15 degrees or less in one pass by submerged arc welding, a predetermined leading electrode and trailing electrode are provided. A method of using and welding is described. Note that welding in which a plurality of electrodes are arranged before and after the welding direction is generally called tandem welding.

  Further, in Patent Document 2, the flow of the molten metal is controlled by applying a forced magnetic field to the molten pool while the plurality of electrodes are translated at a predetermined lateral interval across the welding line, and the welding efficiency is improved. A multi-electrode submerged arc welding method is described which seeks to improve and improve weld quality. Note that welding in which a plurality of electrodes are arranged on the left and right with respect to the welding direction is generally called parallel welding.

Kobe Steel Engineering Reports Vol. 31, no. 4, p. 77-80

JP-A-60-177966 JP-A-55-136571

  However, even when the groove is narrowed, in the case of thick plate multi-layer welding, in practice, two-pass welding is often performed in consideration of securing joint performance and slag peelability. In particular, when the flux is solidified in the groove, the slag bites into the groove wall or becomes stretched on both the groove walls, making it difficult to peel off the slag. Therefore, one layer of welding is divided into a plurality of passes so that no slag adheres to the surface.

  In addition, in multi-pass multi-pass welding, bead distribution is performed, so the wire aiming position must be adjusted and work efficiency is reduced. There is a problem that the joint performance varies from part to part. Further, in the submerged arc welding, since the welding state cannot be visually confirmed, adjustment of the wire aiming position and the like depends on the skill and experience of the operator, and it is difficult to perform stable welding.

  Furthermore, in the case of narrow gaps and multiple electrodes, undercuts generally occur, making it difficult to remove slag or causing hot cracks, so welding conditions such as welding current and welding speed There is also a problem that it is difficult to manage.

  The present invention was devised in view of the above-described problems, and an object thereof is to provide a submerged arc welding method and apparatus capable of laminating and welding in one pass even with a wide groove shape. .

According to the present invention, there is provided a submerged arc welding method in which a plurality of electrodes are arranged in a direction crossing the welding direction and the joint is laminated and welded, and a phase difference of an alternating current sent to the electrodes is determined by the joint. Phase control setting step that is set according to the type, and interelectrode distance that sets the interelectrode distance when the electrodes are arranged in parallel in the width direction of the groove shape of the joint within a range in which one molten pool can be formed A setting step, an electrode support angle adjustment step for adjusting the crossing angle between the parallel direction of the electrodes and the welding direction while maintaining the distance between the electrodes, and a welding construction step for laminating and welding the joint in a single pass, A submerged arc welding method is provided.

  In the inter-electrode distance setting step, the inter-electrode distance may be set in consideration of the groove shape and the number of stacked layers.

  In the electrode support angle adjusting step, the intersecting angle may be adjusted in consideration of the amount of penetration of the groove shape in the wall direction, and the intersecting angle or the inter-electrode distance may be determined for each weld layer. You may make it adjust to.

The Te phase control setting step smell, pre Symbol retardation may be set in the range of 0 ° to 90 °.

  Prior to the welding construction step, it may have a current waveform adjustment step for shifting the EN polarity ratio of the alternating current waveform to the negative side, and a current value for adjusting the current value flowing through the electrode for each weld layer You may make it have an adjustment process. The groove shape preferably has a maximum width larger than 25 mm.

In addition, according to the present invention, there is provided a submerged arc welding apparatus in which a plurality of electrodes are arranged in a direction intersecting the welding direction and the joints are laminated and welded, and the distance between the electrodes of the electrodes is formed as one molten pool. An inter-electrode distance changing mechanism that holds the electrodes so that the electrodes can be changed within a possible range, and holds the electrodes so that the crossing angle between the parallel direction of the electrodes and the welding direction can be adjusted while maintaining the inter-electrode distance. possess a crossing angle adjusting mechanism, a phase difference of the alternating current flowing sent to the electrode is set according to the type of the joint, submerged arc welding apparatus is provided, characterized in that.

  According to the above-described submerged arc welding method according to the present invention, the molten metal penetration shape can be set by the phase control setting step, and welding can be performed with a bead width suitable for the groove shape by the inter-electrode distance setting step. The slag peelability can be improved by the electrode support angle adjusting process, and the lamination welding can be further performed in one pass by the welding construction process. In other words, according to the present invention, by setting the welding conditions such as electrode arrangement in consideration of the penetration shape and slag peelability, it is possible to perform laminar welding in one pass even with a wide groove shape. it can. As a result, homogenization of joint performance can be achieved, work depending on the skill of the operator such as the wire aiming position can be omitted, and stable welding can be performed.

  In addition, according to the above-described submerged arc welding apparatus according to the present invention, the interelectrode distance changing mechanism and the crossing angle adjusting mechanism can be arranged, so that the interelectrode distance and the crossing angle can be easily changed or adjusted. A plurality of electrodes can be arranged so that even one groove shape can be laminated and welded in one pass.

It is process drawing which shows the submerged arc welding method which concerns on embodiment of this invention. It is sectional drawing which shows the joint welded in embodiment of this invention, (a) is before welding construction, (b) has shown after welding construction. It is explanatory drawing of a phase control setting process, (a) shows the case where phase difference is 0 degree, (b) shows phase difference 90 degree, (c) shows phase difference 180 degree. It is explanatory drawing of electrode arrangement | positioning, (a) has shown the distance setting process between electrodes, (b) has shown the electrode support angle adjustment process. It is explanatory drawing at the time of adjusting a crossing angle for every weld layer, (a) is the uppermost layer, (b) Intermediate layer, (c) is the lowermost layer, (d) Furthermore, the uppermost layer which adjusted the distance between electrodes, Show. It is explanatory drawing of the modification of the submerged arc welding method which concerns on this embodiment, (a) is process drawing, (b) is a current waveform figure, (c) is the relationship between a current waveform, slag thickness, and wire welding speed. FIG. It is a schematic block diagram which shows the submerged arc welding apparatus which concerns on embodiment of this invention, (a) is a side view, (b) has shown the b arrow view in Fig.7 (a).

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. Here, FIG. 1 is a process diagram showing a submerged arc welding method according to an embodiment of the present invention. FIG. 2 is a cross-sectional view showing a groove shape of a joint to be welded in the embodiment of the present invention. FIG. 3 is an explanatory diagram of the phase control setting process, in which (a) shows a phase difference of 0 °, (b) shows a phase difference of 90 °, and (c) shows a phase difference of 180 °. 4A and 4B are explanatory diagrams of electrode arrangement, where FIG. 4A shows an inter-electrode distance setting step, and FIG. 4B shows an electrode support angle adjustment step.

  A submerged arc welding method according to an embodiment of the present invention is a submerged arc welding method in which a plurality of electrodes 1a and 1b are arranged in a direction crossing the welding direction and the joint 2 is laminated and welded, and is shown in FIG. As described above, the required quality acquisition step (Step 1) for obtaining the required quality of the joint 2 after welding, the welding material selection step (Step 2) for selecting the welding material according to the required quality of the joint 2, and the required quality of the joint 2 The groove shape design step (Step 3) for designing the groove shape according to the above, the phase control setting step (Step 4) for setting the phase difference of the alternating current sent to the electrodes 1a and 1b, and the electrodes 1a and 1b. The inter-electrode distance setting step (Step 5) for setting the inter-electrode distance S when arranged in parallel in the width direction of the two groove shapes, and the electrode for adjusting the crossing angle θ between the parallel direction of the electrodes 1a and 1b and the welding direction Holding angle adjustment step (Step 6), welding operation condition setting step (Step 7) for setting the remaining welding conditions such as current magnitude and welding speed, and welding operation step (Step 8) for laminating and welding the joint 2 in one pass. And).

  The required quality acquisition step (Step 1) is a step of acquiring basic information necessary for welding, such as the material of the base material, the type of the joint 2, the strength required for the joint 2, and the mechanical properties. Examples of the joint 2 include a butt joint, a T joint, a cross joint, a square joint, a lap joint, and a contact plate joint. The strength of the joint 2 is calculated from the material of the base material, the plate thickness, the use of the joint 2, the usage environment, and the like.

  The welding material selection step (Step 2) is a step of selecting a suitable welding material according to the required quality obtained in Step 1. In submerged arc welding, the type of wire and flux (solvent) is selected as the welding material. In addition to the wires shown in the JIS standard, commercially available wires for high tensile steel, low alloy steel, stainless steel, etc. can be used. As the flux, a melt flux or a fired flux suitable for the base material and the selected wire is selected.

  The groove shape design step (Step 3) is a step of designing a groove shape based on the required quality obtained in Step 1 and the welding material selected in Step 2. There are various types of groove shapes such as I shape, V shape, Y shape, Les shape, X shape, K shape, J shape, U shape, and H shape. Hereinafter, description will be made assuming a U-shaped groove shape as shown in FIG.

  The groove shape shown in FIG. 2 (a) is a U-shaped groove shape constituting a butt joint made of a steel material having a thickness T, and a groove depth D, a groove angle φ, a groove width (intermediate portion). The groove width is Wx, and the maximum width of the groove width is Wmax.), The bottom radius R, and a predetermined route interval (here, 0). The plate thickness T is, for example, 150 mm or more, the groove width is a size that is not narrowed, and the maximum width Wmax is set to be larger than, for example, 25 mm. However, it is not intended to exclude that the maximum width Wmax is 25 mm or less, but is not intended to be narrowed intentionally even if the maximum width Wmax is about 20 mm. The groove angle φ is designed according to the relationship with the groove depth D. For example, in the case of a thick steel material, the groove angle φ is set in a range of about 5 to 30 °.

The phase control setting step (Step 4) is a step of adjusting the penetration amount of the molten metal. In general, when two AC welding power sources are used, the arc interference is controlled by shifting the phase by the primary side connection method. In this embodiment, the phase difference between the two electrodes is also controlled, and the bead due to arc interference is used. The change in shape was confirmed. The basic test result by bead-on-plate welding is shown in FIG. Here, the phase difference was evaluated for three types of 0 °, 90 °, and 180 ° shown in FIGS. In each figure, one electrode is shown by a solid line and the other electrode is shown by a broken line.

  As shown in FIG. 3A, when the phase difference was 0 °, the arc attracted, so that a weld bead having a narrow width and a deep penetration was obtained. As shown in FIG. 3C, the arc was repelled at a phase difference of 180 °, so that it was divided into two weld beads. Further, as shown in FIG. 3B, when the phase difference was 90 °, the arc repeatedly attracted and repelled alternately, and a weld bead having a shallower penetration and a wider width was obtained compared to the phase difference of 0 °. When a dent is formed at the center of the bead, a weld defect is likely to occur. Therefore, in the present embodiment, the phase difference is preferably set within a range of 0 ° to 90 °. In particular, by setting the phase difference to 90 ° or the vicinity thereof, a wide bead without a dent can be obtained. In addition, since the bead width can be controlled by controlling the phase difference, a weld bead suitable for each weld layer can be obtained by setting the phase difference in accordance with the groove width of each weld layer when performing lamination welding. Can be obtained.

  Moreover, since this phase difference accompanies the change of the penetration amount, it is preferable to set it according to the type of the joint 2. Further, which phase difference is set for which joint 2 is selected based on the results of test data, experience values, simulations, and the like acquired in advance. Thus, by setting the phase difference for each type of joint 2, work efficiency can be improved, and even a less experienced worker can easily set a phase difference suitable for the type of joint 2. can do. Although a case where a digital AC power source is used as a power source is illustrated here, the phase difference may be controlled by an analog power source.

  In the inter-electrode distance setting step (Step 5), as shown in FIG. 4A, the inter-electrode distance is an interval when the electrodes 1a and 1b are arranged in a direction orthogonal to the welding direction (so-called parallel). This is a step of setting S. This is a result of studying the arrangement of the two electrodes 1a and 1b perpendicular to the weld line in order to obtain a wide weld bead. The inter-electrode distance S is set to a distance that can be welded in one more pass with respect to at least the maximum width Wmax of the groove width in consideration of the wire diameter. Further, the interelectrode distance S may be set in consideration of the groove shape and the number of layers, assuming welding within the groove. By considering the groove shape and the number of layers, the lowermost layer and the intermediate layer can be further welded one pass at the same interelectrode distance S by adjusting the current value and the welding speed. For example, in a U-shaped groove shape with a bottom radius R = 10 mm, a groove depth D = 20 mm, and a groove angle φ = 10 °, three layers are welded one pass at a time with a wire diameter of 4.0 mm and a phase difference of 90 °. In this case, the inter-electrode distance S is set to 8 mm.

  The electrode support angle adjustment step (Step 6) is a step of adjusting the intersection angle θ between the electrodes 1a and 1b as shown in FIG. For example, the intersection angle θ is set based on the parallel arrangement shown in FIG. 4A (intersection angle θ = 0 °). Here, in the electrode arrangement (θ = 0 °) shown in FIG. 4A, the slag peelability was evaluated by changing the heat input and changing the thickness of the slag. As the slag became thinner, the slag peelability improved. There was a trend. Therefore, by changing the electrode arrangement (intersection angle θ), the distance C between the electrodes 1a and 1b and the groove wall was changed, and the influence on the slag peelability was verified. The slag peelability was improved by changing the electrode arrangement from θ = 30 ° to θ = 45 °.

  In order to improve the slag peelability, it has been reported that the amount of slag shrinkage during cooling is larger than the amount of shrinkage of the groove and undercut does not occur, and this time, the electrodes 1a and 1b and the groove are reported. It is thought that the penetration in the groove wall direction is reduced by the separation of the distance C from the wall, and the shrinkage amount in the bead width direction during cooling is affected. Therefore, the crossing angle θ is preferably adjusted in consideration of the amount of penetration of the groove shape in the wall direction. Further, the crossing angle θ is set so that the distance C between the electrode 1a and the electrode 1b is the same distance. The crossing angle θ is adjusted within a range of 0 to 90 °.

  In the electrode support angle adjustment step (Step 6), the crossing angle θ may be adjusted for each weld layer. Here, FIG. 5 is an explanatory view when the crossing angle θ is adjusted for each weld layer, (a) is the uppermost layer, (b) the intermediate layer, (c) is the lowermost layer, and (d) is further between the electrodes. The top layer with the distance adjusted is shown. As shown in FIGS. 5A to 5C, the groove width of the groove shape shown in FIG. 2A is the maximum width Wmax, the intermediate width Wx, and the minimum width from the top layer to the bottom layer. It becomes narrower in the order of Wmin. In the uppermost layer shown in FIG. 5A, the crossing angle θ = 0 ° (parallel arrangement), in the intermediate layer shown in FIG. 5B, the crossing angle θ = 45 ° (lamination arrangement), and in FIG. In the lowermost layer shown, the intersection angle θ is set to 90 ° (tandem arrangement). Thus, by individually setting the crossing angle θ for each weld layer, one-pass welding can be easily performed under conditions suitable for each weld layer, and the slag peelability in each weld layer can be improved. .

  Furthermore, as shown in FIG. 5D, when performing wide and multi-layer welding, the inter-electrode distance S may be adjusted in addition to the intersection angle θ. Specifically, the inter-electrode distance S is adjusted to be increased to the inter-electrode distance S ′ from the state of the intersection angle θ = 0 ° (parallel arrangement). Thus, by adjusting both the crossing angle θ and the inter-electrode distance S for each weld layer, a joint such as a groove shape having a maximum groove width Wmax or a groove shape having a deep groove depth D is obtained. 2 can be optimally arranged, and each weld layer can be welded in a single pass. Note that, depending on the groove shape, only the inter-electrode distance S may be adjusted to weld each weld layer in a single pass.

  The welding construction condition setting step (Step 7) is a step of setting the remaining welding construction conditions that were not set in Steps 1 to 6 described above. Specifically, conditions necessary for submerged arc welding such as a current value, a voltage value, a welding speed, a preheating temperature, a temperature between passes, a heat treatment after welding, and a backing are set. Moreover, in this welding construction condition setting process (Step 7), you may make it include the electric current value adjustment process which adjusts the electric current value sent through the electrodes 1a and 1b for every welding layer. By increasing the current value, the diameter of the molten pool of the electrodes 1a and 1b can be increased and the bead width can be increased. Therefore, this is the case where lamination welding is performed at a constant interelectrode distance S and crossing angle θ. However, the bead width required for each weld layer can be obtained by adjusting the current value. Even when the crossing angle θ is adjusted for each weld layer, the interelectrode distance S is not changed instead of increasing the interelectrode distance S to the interelectrode distance S ′ as shown in FIG. The same effect can be obtained by increasing the current value as it is.

  The said welding construction process (Step8) is a process of constructing welding by the welding construction conditions set by the process of Step1-Step7 mentioned above. According to the present embodiment, the electrode arrangement is performed in consideration of the penetration shape and the slag peelability by including the phase control setting step (Step 4), the inter-electrode distance setting step (Step 5), and the electrode support angle adjustment step (Step 6). As shown in FIG. 2B, even if the groove shape is wide, it can be laminated and welded in a single pass. As a result, the joint performance can be homogenized in the weld layer, and the adjustment for ensuring the joint performance can be easily performed. In addition, the operation depending on the skill of the operator such as the wire aiming position can be omitted, and stable welding can be performed.

  Next, a modified example of the above-described submerged arc welding method according to the present embodiment will be described. Here, FIG. 6 is explanatory drawing of the modification of the submerged arc welding method which concerns on this embodiment, (a) is process drawing, (b) is a current waveform figure, (c) is a current waveform and slag thickness. FIG. 6 shows a relationship diagram between wire welding speed and wire welding speed.

  As shown in FIG. 6A, in this modification, an alternating current is applied between the electrode support angle adjustment step (Step 6) and the welding execution condition setting step (Step 7), which are before the welding execution step (Step 8). A current waveform adjustment step (Step 9) for shifting the EN polarity ratio of the waveform to the negative side; In the current waveform adjustment step (Step 9) in this modification, as shown in FIG. 6B, using a digital AC power source, the positive / negative time ratio (balance) of the current waveform and the positive / negative current value ratio (offset) ) And both. The EN polarity ratio means to include both the time ratio (balance) and the current value ratio (offset) described above, and only one of them may be adjusted.

  As shown in FIG. 6B, the conventional current waveform has a positive / negative time ratio (balance) with respect to the time of the waveform period of 50%. In this modification, the balance amount (positive time ratio) is 35. % (That is, the negative time ratio is set to 65%). The balance amount is preferably adjusted in the range of 25% ≦ balance amount (positive time ratio) <50%, for example. In the conventional current waveform, the negative current value ratio (offset) with respect to the waveform amplitude is 0%. In this modification, the offset amount is set to -15% (15% on the negative side). For example, when the current setting is 600 A and the offset amount is −15%, the positive current value is 510 A and the negative current value is 690 A in the calculation. However, when the power source is controlled so that the effective value becomes the set value, the actual current value may slightly deviate from the calculated value described above. The offset amount is preferably adjusted in a range of −25% ≦ offset amount <0%, for example.

  In this way, by shifting the EN polarity ratio of the current waveform to the negative side, the amount of heat input to the flux can be reduced, and the slag generation amount can be controlled. Here, FIG. 6C is a result of investigating the relationship between the slag thickness and the wire welding speed using the specimen having the EN polarity ratio shown in FIG. 6B. In this figure, the white circle and solid line are the slag thickness (mm), the white triangle and the alternate long and short dash line are the wire welding speed (m / min) at the start, and the black triangle and the alternate long and short dash line are the wire welding speed (m / min) at the end. Show. As shown in the figure, it was confirmed that the wire welding speed increased by shifting the EN ratio to the negative side, while the slag thickness decreased, and the slag peelability was improved. Note that the thickness of the weld layer (welded metal) can be properly maintained by increasing the welding speed by the amount corresponding to the increase in the wire welding speed.

  In this test, in a U-shaped groove shape having a bottom radius R = 10 mm, a groove depth D = 20 mm, and a groove angle φ = 10 °, the wire diameter is 4.0 mm, the interelectrode distance S = 8 mm, and the crossing angle θ. When the three layers were welded one pass at a phase difference of 90 ° under the condition of = 45 °, a slag with a thickness of 9 mm was generated, and the peelability was also good. Moreover, the weld bead toe of each layer was smooth and had good wettability, sufficient penetration, and good results without weld defects were obtained.

  Then, the submerged arc welding apparatus which concerns on embodiment of this invention is demonstrated. Here, FIG. 7 is a schematic configuration diagram illustrating a submerged arc welding apparatus according to an embodiment of the present invention, in which (a) is a side view and (b) is a view as viewed in the direction of arrow b in FIG. 7 (a). ing.

  As shown in FIG. 7, the submerged arc welding apparatus according to the present embodiment is a submerged arc welding apparatus that places a plurality of electrodes 1a and 1b in a direction intersecting the welding direction and welds the joint 2 by lamination. The interelectrode distance changing mechanism 3 that holds the electrodes 1a and 1b so that the interelectrode distance S can be changed, and the crossing angle θ between the parallel direction of the electrodes 1a and 1b and the welding direction can be adjusted. And an intersecting angle adjusting mechanism 4 that holds 1a and 1b.

  The electrodes 1a and 1b are constituted by a torch 11 having a contact tip and a wire 12, and are configured so that the wire 12 can be automatically fed out by a wire feeding device (not shown). Moreover, although not shown in figure, the flux supply apparatus is arrange | positioned in the position ahead of the electrodes 1a and 1b. The wire feeding device, the flux feeding device, and the like are mounted on a cart 5 that can move along the welding direction.

  The inter-electrode distance changing mechanism 3 is configured by a mechanism for holding the torches 11 of the electrodes 1a and 1b so as to be slidable in the horizontal direction. Specifically, the inter-electrode distance changing mechanism 3 includes, for example, a plate-shaped electrode support member 31 and a rail 32 disposed on the electrode support member 31. The torch 11 is slidably locked on the rail 32 manually or automatically, and is configured to be fixed at a predetermined position. The inter-electrode distance changing mechanism 3 is merely an example, and is not limited to the illustrated configuration, and may be configured using any one of a rack and pinion mechanism, an actuator, an electric motor, and the like.

  The crossing angle adjusting mechanism 4 is configured by a mechanism that rotates the electrodes 1a and 1b arranged at a predetermined interelectrode distance S so as to cross the welding direction. Specifically, the crossing angle adjustment mechanism 4 includes, for example, a rotation shaft 41 connected to the electrode support member 31 and a rotation shaft support member 42 that rotatably supports the rotation shaft 41. The The rotation shaft 41 is connected to the back surface of the electrode support member 31 so as to extend in a direction orthogonal to the rail 32. The rotation shaft support member 42 is also an arm portion that connects the rotation shaft 41 and the carriage 5. The rotation shaft 41 is inserted through a through hole formed at the tip of the rotation shaft support member 42.

  The rotation shaft 41 may be manually rotated, but an electric motor or a rotary encoder may be disposed on the rotation shaft 41 so that the rotation shaft 41 can be automatically rotated. Although not shown, a lock mechanism is disposed on the rotation shaft 41 and the rotation shaft support member 42 so that the rotation shaft 41 (that is, the electrodes 1a and 1b) can be fixed at a predetermined intersection angle θ. . The lock mechanism may mechanically constrain the rotation shaft 41 by a pin or hook, or may constrain the rotation shaft 41 by a brake by an electric motor.

  When the crossing angle θ of the electrodes 1a and 1b is changed for each weld layer, the crossing angle θ may be manually adjusted for each weld layer, or an electric motor or a rotary encoder may be attached to the rotating shaft 41. When these are arranged, these may be connected to a control device and the crossing angle θ may be adjusted by an electrical signal.

  According to the above-described submerged arc welding apparatus according to the present embodiment, the interelectrode distance changing mechanism 3 and the crossing angle adjusting mechanism 4 are arranged, so that the interelectrode distance S and the crossing angle θ can be easily changed or adjusted. A plurality of electrodes can be arranged so that even a wide groove shape can be laminated and welded in one pass. Further, it is possible to perform lamination welding while changing or adjusting the interelectrode distance S and the crossing angle θ for each weld layer with a single submerged arc welding apparatus.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention, such as being applicable to multi-electrode submerged arc welding using three or more electrodes. Of course.

DESCRIPTION OF SYMBOLS 1a, 1b ... Electrode 2 ... Joint 3 ... Interelectrode distance change mechanism 4 ... Intersection angle adjustment mechanism 5 ... Carriage 11 ... Torch 12 ... Wire 31 ... Electrode support member 32 ... Rail 41 ... Turning shaft 42 ... Turning shaft support member

Claims (9)

A submerged arc welding method in which a plurality of electrodes are arranged in a direction crossing the welding direction and the joint is laminated and welded,
A phase control setting step for setting the phase difference of the alternating current sent to the electrode according to the type of the joint ;
An inter-electrode distance setting step for setting the inter-electrode distance within a range in which one molten pool can be formed when the electrodes are arranged in parallel in the width direction of the groove shape of the joint;
An electrode support angle adjustment step of adjusting an intersection angle between the parallel direction of the electrodes and the welding direction while maintaining the distance between the electrodes;
A welding process for laminating and welding the joint in a single pass;
A submerged arc welding method characterized by comprising:   2. The submerged arc welding method according to claim 1, wherein in the inter-electrode distance setting step, the inter-electrode distance is set in consideration of the groove shape and the number of stacked layers.   2. The submerged arc welding method according to claim 1, wherein in the electrode support angle adjustment step, the crossing angle is adjusted in consideration of a penetration amount of the groove shape in a wall direction.   2. The submerged arc welding method according to claim 1, wherein, in the electrode support angle adjustment step, the crossing angle is adjusted for each weld layer.   2. The submerged arc welding method according to claim 1, wherein in the phase control setting step, the phase difference is set within a range of 0 ° to 90 °.   2. The submerged arc welding method according to claim 1, further comprising a current waveform adjustment step of shifting the EN polarity ratio of the alternating current waveform to the negative side before the welding construction step.   2. The submerged arc welding method according to claim 1, further comprising a current value adjusting step of adjusting a current value flowing through the electrode for each weld layer before the welding construction step.   The submerged arc welding method according to claim 1, wherein the groove shape has a maximum width greater than 25 mm. A submerged arc welding apparatus for laminating and welding joints by arranging a plurality of electrodes in a direction crossing the welding direction,
An inter-electrode distance changing mechanism for holding the electrodes such that the distance between the electrodes can be changed within a range in which one molten pool can be formed;
Have a, a crossing angle adjustment mechanism for holding the adjustably the electrode crossing angle between the parallel direction and the direction of welding of the electrode while maintaining the distance between the electrodes,
The phase difference of the alternating current sent to the electrode is set according to the type of the joint,
A submerged arc welding apparatus characterized by that.