Electrogas arc welding method

Abstract

To provide an electro gas arc-welding method by which improvement in workability of a welding operator is achieved.SOLUTION: An electro gas arc-welding method has: a first weld zone formation process in which a water-cooled slidable copper strap 4 is installed on a first surface f1 so as to cover at least a part of a first groove part 21 of a pair of steel plates 1, a backing rod stock 3 made of ceramics having a width L6 larger than a root gap L5 is installed by bringing a convex surface thereof into contact with a second groove part 22 so as to cover an opening bottom 220, a welding wire 6 is supplied between the water-cooled slidable copper strap 4 and the backing rod stock 3, and a first weld zone is formed; and a second weld zone formation process in which the backing rod stock 3 is removed from the second groove part 22, the water-cooled slidable copper strap 4 is removed from the first surface f1 and is installed on a second surface f2 so as to cover at least a part of the second groove part 22, the welding wire 6 is supplied between the water-cooled slidable copper strap 4 and the first well zone, and a second weld zone is formed.SELECTED DRAWING: Figure 1

Description

Technical Field

[0006] , ,

[0001] The present invention relates to an electro-gas arc welding method for welding one pass each from both surfaces of a butt joint of a pair of steel plates.

Background Art

[0002] The electro-gas arc welding method is a high-efficiency automatic welding method and is widely used in welding construction of large structures such as the shipbuilding industry, energy industry, and construction industry.

[0003] Patent Document 1 discloses a welding method in which, for a butt joint of a pair of steel plates, a convex copper backing is applied to one surface, and the center part of the plate thickness is welded in a state where a copper backing that can be closely inserted into the groove is used as a back-up on the other surface, and then the grooves on both surfaces are welded.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] According to the welding method disclosed in Patent Document 1, when welding the groove on one side, a copper backing for back-up having a shape that can be closely inserted into the groove on the other side is used. Here, the copper backing is heavier than the non-metal backing and cannot be easily attached to the groove portion as a back-up material. In addition, in order to enable close insertion, it is necessary to match the shapes of the butt joint and the copper backing for back-up. Therefore, when the shapes of the butt joints are different, the copper backing for back-up cannot be repeatedly used. For this reason, the welding method disclosed in Patent Document 1 has a problem that the workability of the welder cannot be improved.

[0006] Therefore, the present invention was devised in view of the above-mentioned problems, and its objective is to provide an electrogas arc welding method that improves the work efficiency of the welding operator. [Means for solving the problem]

[0007] The electrogas arc welding method of the first invention is an electrogas arc welding method for welding a butt joint consisting of two opposing grooves that are continuous via an opening bottom and whose width gradually decreases in the depth direction from both surfaces of a pair of steel plates, wherein a water-cooled sliding copper backing plate that slides in the welding direction is installed on the first surface of the pair of steel plates so as to cover at least a part of the first groove provided on the first surface, and a ceramic backing bar having a width greater than the root spacing of the pair of steel plates is provided on the second surface opposite to the first surface and is connected to the first groove The process includes: a first weld formation step in which the convex curved surface is placed in contact with the opening bottom of a continuous second groove, and a welding wire is supplied between the water-cooled sliding copper backing and the backing rod to form a first weld; and a second weld formation step in which, after the first weld formation step, the backing rod is removed from the second groove, the water-cooled sliding copper backing is removed from the first surface and placed on the second surface so as to cover at least a part of the second groove, and a welding wire is supplied between the water-cooled sliding copper backing and the first weld to form a second weld. The water-cooled sliding copper anvil has a first groove that covers at least a portion of the groove provided in the pair of steel plates, and a second groove whose one end is continuous with the one end of the first groove, wherein the first groove is formed parallel to the first surface and the second surface, and the second groove is formed such that its width continuously increases and its depth continuously increases from the one end continuous with the first groove toward the other end. It is characterized by the following:

[0008] The electrogas arc welding method in the second invention is characterized in that, in the first invention, the backing bar material is circular in cross-sectional view. [Effects of the Invention]

[0009] According to the first and second inventions, a water-cooled sliding copper backing plate is placed on the first surface so as to cover at least a portion of the first groove, a ceramic backing rod having a width greater than the root spacing of a pair of steel plates is placed in contact with the second groove so as to cover the bottom of the opening, and then welding wire is supplied between the water-cooled sliding copper backing plate and the backing rod to form the first weld. In other words, a ceramic backing rod, which is lighter than a copper backing plate, is used. Therefore, the backing rod can be easily attached to the second groove. Also, because the backing rod is placed in contact with the second groove with its convex curved surface, the backing rod can be easily attached. This improves the work efficiency of the welder.

[0010] In particular, according to the second invention, the backing bar is circular in cross-section. Therefore, the backing bar can be attached to the second groove even more easily so as to cover the bottom of the opening, regardless of the shape of the groove. This further improves the work efficiency of the welder. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 is a schematic side view showing an example of a workpiece and welding machine when welding one surface in the electrogas arc welding method of this embodiment. [Figure 2] Figure 2 is a schematic cross-sectional view showing an example of the AA section in Figure 1. [Figure 3] Figure 3 is a schematic side view showing an example of the workpiece and welding machine used when welding the other surface in the electrogas arc welding method of this embodiment. [Figure 4] Figure 4 is a schematic cross-sectional view showing an example of the BB section in Figure 3. [Figure 5] Figure 5 is a schematic diagram showing a modified example of a water-cooled sliding copper anvil used in the electrogas arc welding method of this embodiment, where Figure 5(a) is a front view, Figure 5(b) is a side view, and Figure 5(c) is a top view. [Figure 6]Figure 6 is a schematic cross-sectional view showing the cross-section of Figure 5(a), where Figure 6(a) is the CC section, Figure 6(b) is the DD section, and Figure 6(c) is the EE section. [Figure 7] Figure 7 is a schematic cross-sectional view showing a modified example of section AA of Figure 1. [Modes for carrying out the invention]

[0012] Hereinafter, an example of an electrogas arc welding method as an embodiment of the present invention will be described in detail with reference to the drawings. In each figure, the first direction is X, the second direction is Y which is perpendicular to the first direction X, and the third direction is Z which is perpendicular to both the first direction X and the second direction Y. The configurations in each figure are schematically shown for explanatory purposes, and the size of each component, the size comparison between components, etc., may differ from those shown in the figures.

[0013] (Electrogas arc welding method) An example of the electrogas arc welding method in this embodiment will be described with reference to Figures 1 to 4. The electrogas arc welding method in this embodiment is a welding method in which, as shown in Figure 1 for example, two opposing grooves 21 and 22, which are continuous via opening bottoms 210 and 220 and whose width gradually decreases in the depth direction from both surfaces f1 and f2 of a pair of steel plates 1, are joined together as a butt joint, and both sides are welded in two layers, one pass each. Here, both surfaces f1 and f2 refer to the first surface f1 and the second surface f2 opposite to the first surface f1 shown in Figure 1. Furthermore, when the pair of steel plates 1 are arranged along a planar direction including the first direction X and the second direction Y, the depth direction refers to the direction toward the center from both surfaces f1 and f2 of the pair of steel plates 1 along the third direction Z.

[0014] The electrogas arc welding method involves welding the grooves 2 of a pair of steel plates 1 using welding equipment. Here, the welding equipment includes a backing rod 3, a water-cooled sliding copper backing plate 4, a welding torch 5, and welding wire 6.

[0015] A pair of steel plates 1 are arranged to be spaced apart from each other at a predetermined root interval along a planar direction including, for example, a first direction X and a second direction Y. A pair of steel plates 1 are provided with a beveled portion 2. The pair of steel plates 1 are welded with the beveled portion 2 as a butt joint.

[0016] As dimensions of the pair of steel plates 1, for example, the width L1 along a third direction Z is 80 mm to 100 mm.

[0017] <Beveled portion 2> The beveled portion 2 is composed of, for example, a first beveled portion 21 provided on a first surface f1 and a second beveled portion 22 provided on a second surface f2 opposite to the first surface f1. The first beveled portion 21 faces the second beveled portion 22. Each beveled portion 21, 22 has an opening bottom 210, 220 that opens at the bottom. The opening bottom 210 of the first beveled portion 21 is continuous with the opening bottom 220 of the second beveled portion 22. That is, the first beveled portion 21 is continuous with the second beveled portion 22 through each opening bottom 210, 220. The beveled portion 2 may be provided with a root face 23 that connects each opening bottom 210, 220.

[0018] As dimensions of the beveled portion 2, for example, when L1 is 100 mm, the depth L2 of the first beveled portion 21 along the third direction Z is about 49 mm, the depth L3 of the second beveled portion 22 along the third direction Z is about 49 mm, the width L4 of the root face 23 along the third direction Z is about 2 mm, and the width L5 of the root interval along the second direction Y is about 8 mm. Also, as the bevel angle, for example, the bevel angle of the first beveled portion 21 is about 20°, and the bevel angle of the second beveled portion 22 is about 20° similar to the first beveled portion 21. The bevel angle of the second beveled portion 22 may be different from the bevel angle of the first beveled portion 21.

[0019] Next, the backing bar 3, water-cooled sliding copper electrode 4, and welding torch 5 used as welding equipment will be described.

[0020] <Backing bar 3> The backing rod 3 is a backing material used in electrogas arc welding. The backing rod 3 has a rod-like shape with a convex curved surface in part. When welding the first groove 21, the backing rod 3 is installed so that the convex curved surface abuts against the second groove 22 so as to cover the bottom of the opening 220. In this case, the backing rod 3 can be easily attached to a groove with a different shape from the groove 2. This improves the work efficiency of the welder.

[0021] The backing bar 3 may, for example, be circular in cross-section. In this case, the backing bar 3 can be attached to the second groove 22 more easily so as to cover the bottom of the opening 220, regardless of the shape of the groove 2. This further improves the work efficiency of the welder.

[0022] The width L6 of the backing rod 3 is greater than the width L5 of the root spacing, for example, 9 to 12 mm. By using this backing rod 3, it can be brought into contact with the second groove 22 so as to cover the opening bottom 220 of the second groove 22.

[0023] The length of the backing bar 3 is, for example, 30 to 40 mm. Multiple backing bars 3 may be attached in a continuous manner along the welding direction F1, as shown in Figure 2, for example.

[0024] The backing rod 3 is made of ceramics. The composition of the backing rod 3 is not particularly limited, but examples include cordierite, which mainly consists of alumina, silicon dioxide, and magnesium oxide. Corderite has a lower coefficient of thermal expansion than general alumina, and is superior in thermal shock resistance and mechanical strength, and is also lighter than metal.

[0025] <Water-cooled sliding copper anvil 4> The water-cooled sliding copper backing plate 4 is a copper backing plate used in electrogas arc welding. The water-cooled sliding copper backing plate 4 is installed on both surfaces f1 and f2 so as to cover at least a portion of the groove 2, as shown in Figure 1, for example. The water-cooled sliding copper backing plate 4 is mounted on a welding trolley (not shown), for example, and slides along both surfaces f1 and f2 as welding of the groove 2 progresses.

[0026] The water-cooled sliding copper backing plate 4 includes a backing plate block 41 and a shielding gas hood 42. The surfaces of the backing plate block 41 that are installed on both surfaces f1 and f2 have installation surfaces 41a and 41b, and a concave curved groove 43 provided between the installation surfaces 41a and 41b. When the water-cooled sliding copper backing plate 4 is installed on both surfaces f1 and f2, the installation surfaces 41a and 41b contact both surfaces f1 and f2, and the groove 43 of the backing plate block 41 covers at least a portion of the groove 2.

[0027] The metal block 41 has, for example, a cold water pipe 411 inserted inside. The vicinity of the groove 43 of the metal block 41 is cooled by the flow of cold water through the cold water pipe 411.

[0028] The shielding gas hood 42 has, for example, a gas pipe 421 inserted inside. The shielding gas hood 42 blocks the area of ​​the groove 2 covered by the water-cooled sliding copper backing plate 4 from the atmosphere by blowing a shielding gas such as carbon dioxide gas toward the groove 2.

[0029] <Welding Torch 5> The welding torch 5 supplies welding wire 6 to the area of ​​the groove 2 covered by the water-cooled sliding copper backing plate 4. The welding torch 5 is mounted on a welding trolley (not shown), for example, and slides along both surfaces f1 and f2 as welding of the groove 2 progresses.

[0030] <Welding wire 6> The welding wire 6 is supplied to the area of ​​the groove 2 covered by the water-cooled sliding copper backing plate 4, and melts within the groove 2 while generating an arc, forming molten metal. The molten metal filling the groove 2 is cooled and solidified by the water-cooled sliding copper backing plate 4, forming a weld bead.

[0031] As for the material of the welding wire 6, for example, flux-cored wire for electrogas arc welding as described in "JIS Z 3319:1999 / AMENDMENT 1:2007", or known solid wire for electrogas arc welding can be used.

[0032] Next, the procedure for the electrogas arc welding method will be described. The electrogas arc welding method comprises a first weld formation step and a second weld formation step. In the electrogas arc welding method, the second weld formation step is performed after the first weld formation step. In this embodiment, the method of having an operator perform the various steps will be described, but at least some of the steps may be performed via control equipment externally connected to various welding machines.

[0033] <First welding joint formation process> In the first weld formation process, the worker, for example as shown in Figure 2, places a water-cooled sliding copper backing plate 4 on the first surface f1 so as to cover at least a portion of the first groove 21, and places a backing rod 3 in contact with the second groove 22 so as to cover the bottom of the opening 220. Then, the worker slides the water-cooled sliding copper backing plate 4 in the welding direction F1, and while blowing shielding gas into the first space Q1 between the water-cooled sliding copper backing plate 4 and the backing rod 3, supplies the welding wire 6 to form the first weld, which is the weld bead, the first weld 81. Specifically, the supplied welding wire 6 melts due to the heat of an arc (not shown) generated between the welding wire 6 and the molten pool 71, and is cooled by the water-cooled sliding copper backing plate 4 to form the first weld 81. The backing rod 3 is detachably attached near the bottom of the opening 220 of the second groove 22 by being supported, for example, by a steel metal plate 31. The metal plate 31 is supported by one or more steel restraint plates 33 that are temporarily welded to the second surface f2 of a pair of steel plates 1, for example. The worker may firmly support the backing bar material 3 with the metal plate 31 by driving a steel wedge 32 between the metal plate 31 and the restraint plate 33, for example. Since the temporarily welded part can be easily destroyed by impacting the restraint plate 33, the worker can easily remove the restraint plate 33 from the second surface f2 by striking the restraint plate 33 with a hammer or the like after forming the first weld 81, for example.

[0034] In this case, the backing rod 3, which is lighter than the copper backing plate, can be easily attached to the second groove 22. This improves the work efficiency of the welder. Also, since the backing rod 3 is made of ceramics, which has a higher melting point than the welding wire 6, it is partially melted by the molten pool 71. Subsequently, a portion of the molten backing rod 3 becomes part of the molten slag 91 that is generated on the molten pool 71 formed in the groove.

[0035] Molten slag 91 is generated on the molten pool 71. The molten slag 91 is discharged as appropriate from between the formed first weld 81 and the groove 43 of the water-cooled sliding copper anvil 4 (molten slag 910). The discharged molten slag 910 covers the surface of the first weld 81 and improves the appearance of the first weld 81 in the groove 43. Also, since the melting point of the molten slag 910 is lower than the melting point of the first weld 81, as it moves in the welding direction F1, it solidifies in the middle of the groove 43 and becomes solidified slag 911. The solidified slag 911 is removed from the surface of the first weld 81 after the formation of the first weld 81.

[0036] <Second Weld Formation Process> After the first weld formation process, in the second weld formation process, the worker removes the backing bar 3 from the second groove 22, for example, as shown in Figure 3. The worker also removes the water-cooled sliding copper backing plate 4 from the first surface f1 and places it on the second surface so as to cover at least a portion of the second groove 22.

[0037] Subsequently, the worker, for example as shown in Figure 4, slides the water-cooled sliding copper backing plate 4 in the welding direction F1 while supplying the welding wire 6 to the second space Q2 between the water-cooled sliding copper backing plate 4 and the first weld 81 to form the second weld 82, which is the weld bead. More specifically, the welding wire 6 is melted while an arc is generated between the welding wire 6 and the molten pool 72 to form molten metal.

[0038] Molten slag 92 is generated on the molten pool 72. The molten slag 92 is discharged as needed from between the forming second weld 82 and the groove 43 of the water-cooled sliding copper backing plate 4 (molten slag 920). The molten slag 920 covers the surface of the second weld 82 and improves the appearance of the second weld 82 in the groove 43. Also, since the melting point of the molten slag 920 is lower than the melting point of the second weld 82, as it moves in the welding direction F1, it solidifies in the middle of the groove 43 and becomes solidified slag 921. The solidified slag 921 is removed from the surface of the second weld 82 after the formation of the second weld 82.

[0039] The electrogas arc welding method is completed by performing the steps described above. Note that the welding direction in the first weld formation step may differ from the welding direction in the second weld formation step. Also, if the first weld formation step is performed with the first groove 21 facing upwards and the second groove 22 facing downwards, the pair of steel plates 1 may be rotated so that the second groove 22 faces upwards before performing the second weld formation step.

[0040] Furthermore, although this embodiment describes a one-electrode welding method using one welding torch 5 and one welding wire 6, a so-called two-electrode or more welding method using two or more welding torches 5 and two or more welding wires 6 may also be applied. In this case, the welding wire 6 may be two or more flux-cored wires for electrogas arc welding, two or more solid wires for electrogas arc welding, or a combination of these may be used.

[0041] (Variations of electrogas arc welding method) A modified example of the electrogas arc welding method in this embodiment will be described with reference to Figures 5 to 7. This modified electrogas arc welding method uses a water-cooled sliding copper anvil 4 with the shape shown in Figure 5.

[0042] Figure 5(a) shows the surfaces of the water-cooled sliding copper anvil 4 facing both surfaces f1 and f2 of the pair of steel plates 1, Figure 5(b) shows the right side of the water-cooled sliding copper anvil 4 shown in Figure 5(a), and Figure 5(c) shows the top surface of the water-cooled sliding copper anvil 4 shown in Figure 5(a). The groove 43 of the water-cooled sliding copper anvil 4 consists of a first groove 431 parallel to both surfaces f1 and f2 for forming the weld 8, and a second groove 432 for discharging the molten slags 910 and 920. One end of the second groove 432 is continuous with one end of the first groove 431.

[0043] Furthermore, Figures 6(a) to 6(c) show cross-sections of the backing block 41, which is the base of the water-cooled sliding copper backing 4. Specifically, Figure 6(a) shows the CC cross-section of the water-cooled sliding copper backing 4 shown in Figure 5(a), Figure 6(b) shows the DD cross-section of the water-cooled sliding copper backing 4 shown in Figure 5(a), and Figure 6(c) shows the EE cross-section of the water-cooled sliding copper backing 4 shown in Figure 5(a).

[0044] The width W2 and depth D2 of the second groove 432 in the DD section are greater than the width W1 and depth D1 of the first groove 431 in the CC section. Also, the width W3 and depth D3 of the second groove 432 in the EE section are greater than the width W2 and depth D2 of the second groove 432 in the DD section. In other words, the second groove 432 widens as it moves from one end continuous with the first groove 431 to the other end. , ren It is continuously getting larger and deeper. Specifically, the groove width of the second groove 432 is continuously increasing, with an inclination of θ1 relative to the groove width of the first groove 431, as shown in the plan view in Figure 5(a). Also, the second groove 43 2 is For example, in the side view shown in Figure 5(b), the first groove 43 1 In contrast, it slopes by θ2 and deepens continuously.

[0045] By using this water-cooled sliding copper anvil 4, as shown in Figure 7, for example, the molten slag 91 on the molten pool 71 is discharged more smoothly from between the formed first weld 81 and the groove 43 of the water-cooled sliding copper anvil 4 (molten slag 910a). In this case, it is easier to maintain an appropriate amount of molten slag 91 on the molten pool 71, and slag splashing is reduced, making it possible to weld for a long time. As the discharged molten slag 910a moves in the welding direction F1, it solidifies in the middle of the groove 43 and becomes solidified slag 911a.

[0046] Furthermore, if the width of the second groove 432 is parallel to that of the first groove 431, and only the depth increases continuously, depending on the thickness of the width L1 of the pair of steel plates 1, the amount of molten slag 91 on the molten pool 71 may increase, making it difficult to discharge the molten slag 91 adequately, which may cause slag splashing. Also, if the inclination angle θ2 is set too large to improve the discharge of the molten slag 91, molten metal may flow out of the molten pool 71, which may interrupt welding.

[0047] Therefore, in the water-cooled sliding copper anvil 4 of the present invention, it is preferable that the second groove 432 is continuously increased in width direction by θ1 = 5 to 30° relative to the first groove 431, and continuously increased in depth direction by θ2 = 2 to 10°. In this case, molten metal is not discharged from the molten pool 71, and only the molten slag 91 on the molten pool 71 is smoothly discharged, preventing slag splashing. This enables welding for longer periods of time and further improves the work efficiency of the welder.

[0048] According to this embodiment, a water-cooled sliding copper backing plate 4 is placed on the first surface f1 so as to cover at least a portion of the first groove 21, and a ceramic backing rod 3 having a width L6 greater than the root spacing L5 of the pair of steel plates 1 is placed in contact with the second groove 22 so as to cover the opening bottom 220, and then a welding wire 6 is supplied between the water-cooled sliding copper backing plate 4 and the backing rod 3 to form the first weld 81 in a first weld formation step. In other words, a ceramic backing rod 3, which is lighter than a copper backing plate, is used. Therefore, the backing rod 3 can be easily attached to the second groove 22. Also, since the backing rod 3 is placed in contact with the second groove 22 with its convex curved surface, it can be easily attached to a groove with a different shape from the groove 2. This improves the work efficiency of the welder.

[0049] Furthermore, according to this embodiment, the backing bar 3 is circular in cross-section. Therefore, the backing bar 3 can be attached to the second groove 22 more easily so as to cover the bottom of the opening 220, regardless of the shape of the groove 2. This further improves the work efficiency of the welder.

[0050] While several embodiments of the present invention have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These novel embodiments can be carried out in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents. [Explanation of symbols]

[0051] 1 pair of steel plates 1a, 1b steel plate 2 Bevel section 21 1st groove section 210 (Opening bottom of the first groove) 22 2nd groove section 220 (Opening bottom of the second groove) 23 Root Face 3. Backing rod material 31 Metal plate 32 Wedge 33 Restraint plate 4. Water-cooled sliding copper plate 41. Winning Block 41a, 41b Installation surface 411 Cold water pipe 42 Shielded Gas Hood 421 Gas pipe 43 Groove 431 First Groove 432 Second Groove 5. Welding torch 6. Welding wire 7, 71, 72 Melting pools 8. Welded section 81. First Weld 82 Second Weld 9, 91, 92 Molten slag f1 1st surface f2 2nd surface F1 Welding direction Q1 1st space Q2 2nd space

Claims

1. In an electrogas arc welding method for welding a butt joint consisting of two opposing grooves that are continuous via an opening bottom and whose width gradually decreases in the depth direction from both surfaces of a pair of steel plates, A first weld forming step is to form a first weld by supplying welding wire between the water-cooled sliding copper backing plate and the backing plate, wherein a water-cooled sliding copper backing plate that slides in the welding direction is placed on the first surface of a pair of steel plates so as to cover at least a portion of the first groove provided on the first surface, and a ceramic backing rod having a width greater than the root spacing between the pair of steel plates is placed on the second surface opposite to the first surface so as to contact the opening bottom of the second groove which is continuous with the first groove, and then a welding wire is supplied between the water-cooled sliding copper backing plate and the backing rod, After the first weld formation step, the backing rod is removed from the second groove, the water-cooled sliding copper backing plate is removed from the first surface and placed on the second surface so as to cover at least a portion of the second groove, and then a welding wire is supplied between the water-cooled sliding copper backing plate and the first weld to form a second weld, in a second weld formation step, It has, The water-cooled sliding copper anvil has a first groove that covers at least a portion of the grooves provided in the pair of steel plates, and a second groove whose one end is continuous with one end of the first groove. The first groove is a groove formed parallel to the first surface and the second surface, The second groove is formed such that its width continuously increases and its depth continuously increases from one end continuous with the first groove toward the other end. An electrogas arc welding method characterized by the following.

2. The aforementioned backing bar material is circular in cross-section. The electrogas arc welding method according to claim 1, characterized by the following:

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