Welding method for steel pipe columns

Abstract

To provide a welding method of a steel pipe column which can achieve easier welding of stable quality of an upper part steel pipe column and a lower part steel pipe column.SOLUTION: In a first welding section Pa, a torch 92 is inclined from a position where one plumbing fixture 3 faces toward a rear side of a moving direction D of the torch 92. While keeping the state, as the torch 92 is moved, welding is performed by reducing a retreat angle α of the torch 92 relative to a normal direction of a surface of a steel pipe column 1. In a second welding section Pb, while keeping an inclination angle (the retreat angle) α of the torch 92 in an end edge of the first welding section Pa, the welding is performed by inclining the torch 92 to the rear side of the moving direction D of the torch 92. In a third welding section Pc, the inclination of the torch 92 is varied from an inclination angle (the retreat angle) β of the torch 92 in an end edge of the second welding section Pb to a front side in the moving direction of the torch 92.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a method for welding steel pipe columns that welds upper steel pipe columns and lower steel pipe columns.

Background Art

[0002] As a technique of this kind, for example, Patent Document 1 proposes a method for welding steel pipe columns that welds upper steel pipe columns and lower steel pipe columns while supplying molten welding material to the grooves between the upper steel pipe columns and the lower steel pipe columns.

[0003] Specifically, the upper steel pipe column and the lower steel pipe column, which are temporarily fixed by connecting the erection pieces with an erection jig, are initially welded in multiple layers by a welding robot. After removing the erection jig, the remaining layers are welded by the welding robot.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, when welding the upper steel pipe column and the lower steel pipe column along the circumferential direction of the steel pipe column with a welding robot, depending on the direction of the torch attached to the welding robot, a stable bead may not be formed, and the quality of the welded part may not be satisfactory.

[0006] The present invention has been made in view of such points, and an object thereof is to provide a method for welding steel pipe columns that can perform welding of stable quality between an upper steel pipe column and a lower steel pipe column.

Means for Solving the Problems

[0007] In view of the above problems, the present invention provides a welding method for steel pipe columns, wherein the welding of the upper steel pipe column and the lower steel pipe column, which are temporarily fixed by connecting erection pieces with erection jigs, is performed by moving the torch along the groove while supplying molten welding material from the tip of the torch attached to a welding robot, and welding the upper steel pipe column and the lower steel pipe column, wherein the welding method is performed by welding the upper steel pipe column and the lower steel pipe column with the welding robot between erection jigs that are temporarily fixed along the circumferential direction of the steel pipe column, and in the inter-jig welding section between one erection jig and the other erection jig, the torch is tilted toward the rear in the direction of movement of the torch from the position where the one erection jig faces the other. The welding apparatus is characterized by comprising: a first welding section in which welding is performed while the torch is tilted and the angle of inclination of the torch is reduced with respect to the normal direction of the surface of the steel pipe column as the torch moves; a second welding section continuous with the first welding section, in which welding is performed while maintaining the angle of inclination of the torch at the end of the first welding section and tilting the torch toward the rear in the direction of movement of the torch; and a third welding section continuous with the second welding section, in which welding is performed up to the position where the other erection jig is facing, while changing the angle of inclination of the torch toward the front in the direction of movement of the torch from the angle of inclination of the torch at the end of the second welding section and further increasing the angle of inclination with respect to the normal direction of the surface of the steel pipe column.

[0008] According to the present invention, the upper steel pipe column and the lower steel pipe column can be welded together by supplying molten welding material from the tip of a torch attached to a welding robot to the groove between the upper steel pipe column and the lower steel pipe column, which are temporarily fixed by connecting the erection piece with a jig, while moving the torch along the groove.

[0009] Here, multiple erection jigs are provided at intervals in the circumferential direction of the steel pipe column. In this embodiment, the welding method involves welding the upper and lower steel pipe columns together using a welding robot between the erection jigs that are temporarily fixed along the circumferential direction of the steel pipe column. Specifically, the inter-jig welding section between one erection jig and the other has first to third welding sections.

[0010] In the first welding section, welding is performed with the torch tilted toward the rear in the direction of movement of the torch, starting from a position where one of the erection jigs is facing the other. As the torch moves, the tilt angle (reverse angle) of the torch with respect to the normal direction of the surface of the steel pipe column is reduced. This allows for a stable supply of molten welding material to the groove located opposite one of the erection jigs, while avoiding contact between the torch and one of the erection jigs, and allows the tilt angle of the torch to be changed until the position in the second section described later.

[0011] Here, the initial retraction angle of the torch is not particularly limited, as long as it can stably supply molten welding material to the groove located opposite one of the aligning fixtures. For example, it is preferable that the inclination angle is in the range of 5° to 25° by the time the torch reaches the second welding section (at the end of the first welding section).

[0012] Furthermore, the second welding section is continuous with the first welding section, and in this section, the torch's tilt angle (retraction angle) at the end of the first welding section is maintained, and welding can be performed while tilting the torch toward the rear in the direction of torch movement at a constant retraction angle. In the second welding section as well, molten welding material can be supplied to the groove, enabling stable welding. Here, it is preferable to tilt the torch at a retraction angle of 5° to 25° in the second welding section as well.

[0013] Thus, in the first and second welding sections, welding is performed while tilting the torch so that it faces backward in the direction of torch movement (i.e., welding is performed using the back-reverse method). In this back-reverse method, the molten welding material does not precede the arc, and the molten welding material is pushed upward in the direction of torch movement. As a result, the molten welding material penetrates more easily into the groove, allowing for more reliable and stable welding.

[0014] Furthermore, the third welding section is continuous with the second welding section. In this section, welding can be performed up to the opposing position of the other erection jig while changing the inclination of the torch from the inclination angle of the torch at the end of the second welding section toward the forward side in the direction of torch movement, and further increasing the inclination angle with respect to the normal direction of the surface of the steel pipe column, thereby avoiding contact of the torch with the other erection jig.

[0015] In a preferred embodiment, the steel pipe column is a rectangular steel pipe column, the erection jig is installed on the flat portion, and the second welding section includes a rounded corner connecting it to the flat portion of the steel pipe column.

[0016] In this embodiment, since the surface of the R-shaped corner is curved, it is difficult to form a stable bead with the molten welding material. However, by tilting the torch at a constant retraction angle toward the rear in the direction of torch movement while welding is performed, it is possible to stably supply molten welding material to the groove in such an R-shaped corner while welding is performed.

[0017] In a preferred embodiment, in the first welding section, the inclination angle of the torch is linearly reduced in accordance with the amount of movement of the torch, and in the third welding section, the inclination angle of the torch is linearly increased in accordance with the amount of movement of the torch.

[0018] According to this embodiment, in the first welding section, welding is performed while linearly decreasing the torch tilt angle in accordance with the amount of torch movement, so that a stable welded area (bead) can be formed even when the tilt angle is reduced. Similarly, in the third welding section, welding is performed while linearly increasing the torch tilt angle in accordance with the amount of torch movement, so that a stable welded area (bead) can be formed even when the tilt angle is increased.

[0019] Here, the welding robot described above is not particularly limited in form, as it can move the position of the torch tip of the welding machine to an appropriate position, for example, a welding robot that travels on rails or a welding robot that only rotates. In a more preferred embodiment, the welding robot is an articulated robot, and before welding, a rail installation step is included in which a pair of rails are attached to the lower steel pipe column so as to sandwich the lower steel pipe column, and in the welding, the articulated robot is moved along the rails while welding is performed between the upper steel pipe column and the lower steel pipe column, and after welding is performed multiple times in the welding section between the jigs over the entire circumference of the steel pipe column, the erection jig is removed from the steel pipe column, and in the welding section welded by each articulated robot, welding is performed while tilting the torch toward the rear in the direction of movement of the torch in at least the section where welding begins and the section where welding ends.

[0020] According to this embodiment, even after the erection jig is removed from the steel pipe column, stable welding can be performed by tilting the torch toward the rear in the direction of torch movement in the welding section, excluding at least the welding start section and the welding end section, of the welding section to be welded by each articulated robot. [Effects of the Invention]

[0021] According to the present invention, it is possible to more easily perform welding of stable quality between the upper steel pipe column and the lower steel pipe column. [Brief explanation of the drawing]

[0022] [Figure 1] It is a flowchart for explaining a welding method of a steel pipe column according to an embodiment of the present invention. [Figure 2] It is a side view for explaining the temporary fixing process. [Figure 3] It is a schematic perspective view for explaining the rail mounting process and the robot installation process. [Figure 4] It is a schematic plan view for explaining the first welding process in the state where the building jig is attached. [Figure 5] (a) is a view showing the relationship between the torch and the groove as viewed from the horizontal direction, (b) is a view for explaining the retreat angle of the torch, and (c) is a view for explaining the forward angle of the torch. [Figure 6] It is a schematic diagram for explaining the tilt angle of the torch. [Figure 7] It is a view showing the relationship between the movement amount and the tilt angle of the torch. [Figure 8] It is a schematic plan view for explaining the second welding process after removing the building jig. [Figure 9] It is a schematic perspective view for explaining a welding method of a steel pipe column according to a modified example. [Figure 10] It is a schematic plan view for explaining a welding method of a steel pipe column according to a further modified example shown in FIG. 9.

Embodiments for Carrying Out the Invention

[0023] Hereinafter, a welding method of a steel pipe column according to an embodiment of the present invention will be described with reference to the drawings.

[0024] FIG. 1 is a flowchart for explaining a welding method of a steel pipe column 1 according to an embodiment of the present invention. Hereinafter, as the welding method in the present embodiment, each process from the temporary fixing process S1 to the second welding process S6 shown in FIG. 1 will be described in detail.

[0025] 1. Regarding the temporary fixing process S1, In this embodiment, first, a temporary fixing step S1 is performed. As shown in Figure 2, in the temporary fixing step S1, the upper steel pipe column 10 and the lower steel pipe column 20 are temporarily fixed with the erection jig 3, and then the inclination of the upper steel pipe column 10 is adjusted.

[0026] Here, the upper steel pipe column 10 and the lower steel pipe column 20 are made of polygonal steel pipes formed by four flat sections and four curved sections, and erection pieces 11 and 21 are attached to the four flat sections 10a and 20a of the upper steel pipe column 10 and the lower steel pipe column 20, respectively. Between the flat sections 10a, 10a (20a, 20a), four R-shaped sections 10b (20b) are formed, whose surfaces are curved with a predetermined radius of curvature. Note that the upper steel pipe column 10 and the lower steel pipe column 20 are not limited to the rectangular steel pipe columns shown in Figures 2 and 3, etc., but may be, for example, polygonal steel pipe columns other than rectangular ones (specifically, polygonal steel pipes with four or more faces), multi-faceted box columns such as four-faced box columns, or cylindrical steel pipe columns.

[0027] The lower end edge surface 13 of the upper steel pipe column 10 is a tapered surface that slopes outward, and the upper end edge surface 23 of the lower steel pipe column 20 is a flat surface formed perpendicular to the longitudinal direction of the lower steel pipe column 20. As a result, when the lower end edge surface 13 of the upper steel pipe column 10 is positioned opposite the upper end edge surface 23 of the lower steel pipe column 20, a groove 30 can be formed between the upper steel pipe column 10 and the lower steel pipe column 20, along the circumferential direction of the upper steel pipe column 10 and the lower steel pipe column 20.

[0028] Furthermore, in this embodiment, a backing plate 31 is attached to the inner wall surface of the lower steel pipe column 20 along the circumferential direction, as shown in Figure 5(a). The backing plate 31 protrudes vertically (in the longitudinal direction of the lower steel pipe column 20) from the upper end edge surface 23 of the lower steel pipe column 20, and when the upper steel pipe column 10 is placed on the lower steel pipe column 20, the protruding portion of the backing plate 31 is inserted into the upper steel pipe column 10.

[0029] With this backing plate 31, as will be described later, when the inclination of the upper steel pipe column 10 is adjusted, the gap between the upper steel pipe column 10 and the lower steel pipe column 20 can be covered with the backing plate 31, thereby preventing molten welding material from entering the interior of the steel pipe column 1 during welding. In this embodiment, the backing plate 31 is attached to the inner wall surface of the lower steel pipe column 20, but for example, the backing plate may be attached to the inner wall surface of the upper steel pipe column 10 so as to protrude from the lower end edge surface 13 of the upper steel pipe column 10.

[0030] In the temporary fixing process S1, first, the upper steel pipe column 10 is placed on the lower steel pipe column 20, and the protruding portion of the backing plate 31 is inserted into the upper steel pipe column 10. The upper end of the erection jig 3 is fastened to the erection piece 11 using bolts, and the lower end is fastened to the erection piece 21 using bolts, etc. This connects the erection pieces 11 and 21 of the upper steel pipe column 10 and the lower steel pipe column 20 with the erection jig 3, and the upper steel pipe column 10 and the lower steel pipe column 20 can be temporarily fixed.

[0031] Next, the inclination of the upper steel pipe column 10, which is positioned above the lower steel pipe column 20, is adjusted. This adjusts the verticality between the upper steel pipe column 10 and the lower steel pipe column 20, allowing them to be aligned.

[0032] A detailed explanation of the structure of the erection jig 3 is omitted here, but each erection jig 3 is configured to allow adjustment of the distance between the two erection pieces 11 and 21 that are positioned vertically. This makes it possible to adjust the gap between the upper steel pipe column 10 and the lower steel pipe column 20, which are positioned vertically, as well as to adjust the inclination of the upper steel pipe column 10, which is positioned above. After or during the welding process 7, which will be described later, in the removal process S8, the erection jig 3 is removed from the erection pieces 11 and 21, and the erection pieces 11 and 21 are cut from the upper steel pipe column 10 and the lower steel pipe column 20.

[0033] 2. Regarding rail installation process S2 The rail installation process S2 shown in Figure 1 is performed. In this process, a pair of rails 73, 73 are attached to the lower steel pipe column 20 so as to sandwich the lower steel pipe column 20. In this embodiment, a pair of support pieces 78, 78 are welded to each of the two opposite flat surfaces of the four flat surfaces of the lower steel pipe column 20. In this embodiment, first, the first support member 71 is fixed to the support pieces 78, 78 so as to sandwich the lower steel pipe column 20 with the first support member 71. In this embodiment, the first support member 71 is a long member such as an H-shaped steel, and extends in a direction perpendicular to the rail 73 on which the articulated robot (robot arm) 80, which will be described later, travels.

[0034] Next, a pair of second support members 72 are fixed across a pair of first support members 71 so as to sandwich the lower steel pipe column 20. The second support members 72 are elongated members, and rails 73 are attached to the second support members 72 along their longitudinal direction. Therefore, a pair of rails 73, 73 can be attached to the lower steel pipe column 20 so as to sandwich the lower steel pipe column 20. In this embodiment, the rails 73 are attached to the lower steel pipe column 20 using the first support members 71 and the second support members 72, but for example, the rails 73 may be attached to the lower steel pipe column 20 if sufficient rigidity can be ensured.

[0035] In this embodiment, the rail 73 is a linear guide rail, and a trolley (slider) 74 is attached to the rail 73. The trolley 74 is able to move freely along the rail 73 by a motor (not shown). In this embodiment, the movement control of the trolley 74, the drive control of the articulated robot 80 (described later), and welding according to welding conditions by the torch 92 attached to the tip of the articulated robot 80 are performed by a control device (not shown), but for example, at least a part of these operations may be performed by an operator.

[0036] 3. Regarding the robot installation process S3 Next, the robot installation process S3 shown in Figure 1 is performed. In this process, the articulated robot 80 is installed on the trolley 74. The articulated robot 80 used in this embodiment is a robot that rotates on 6 axes and is a welding robot connected to a welding machine.

[0037] The articulated robot 80 is a welding robot connected to a welding machine (not shown). The articulated robot 80 comprises a base 82 attached to a carriage 74, and a turntable 83 mounted on the base 82 and rotating relative to the base 82. A lower arm 84 is pivotally attached to the turntable 83. A joint 85 is pivotally attached to the tip of the lower arm 84. An upper arm 86 is pivotally attached to the joint 85 with its longitudinal axis as the axis.

[0038] Furthermore, a support arm 87 is attached to the tip of the upper arm 86 to support the welding machine torch 92, which serves as the end effector. The support arm 87 is connected to the upper arm 86, and a cable 91 for feeding welding wire is connected to the torch 92, with the base end of the cable 91 connected to a welding wire feeding device (not shown) for feeding welding wire.

[0039] 4. Regarding the first welding process S4 Next, the first welding process S4 shown in Figure 1 is performed. In this process, the articulated robot 80 performs welding between the upper steel pipe column 10 and the lower steel pipe column 20. In this embodiment, as shown in Figure 4, the articulated robots (welding robots) 80 are set to perform welding in areas A and B, which are separated by a boundary line between opposing rails 73, 73. When welding with each articulated robot 80 within these set areas A and B, the torch 92 is moved along the welding line of the groove 30, and welding material is supplied from the tip of the torch 92 to the groove 30. Specifically, the groove 30 (and its welding line) which circulates along the circumferential direction is divided into four inter-jig welding sections 1L, 1R, ... In this embodiment, the welding line of the groove 30 is divided into four sections sandwiching the erection pieces 11 and 21.

[0040] When welding is performed at each inter-jig welding section 1L, 1R, ... shown in Figure 4, welding is temporarily interrupted and the welding conditions are changed as the articulated robot 80 passes through the erection pieces 11, 21 at the boundaries of the inter-jig welding sections 1L, 1R, ..., allowing for smoother welding. Furthermore, cleaning of the torch 92 and other components can be performed automatically during this welding interruption.

[0041] Here, the torch 92 may be moved multiple times along the welding line of the groove 30 while supplying welding material to form a multi-layered welded portion (bead) 36. In this case, the position of the welding point located at the tip of the torch 92 and the direction of the torch 92 will differ with each movement, so it is suitable to perform welding using an articulated robot when performing such welding. Furthermore, it is preferable that the number of times the torch 92 is moved and welding material is applied is the same in each welding section 1L, 1R, ... between jigs. This makes it possible to suppress the formation of steps in the welded portion (bead).

[0042] In this embodiment, the tips of the torches 92 of a pair of articulated robots 80, 80 are positioned opposite each other across the central axis of the steel pipe column 1 while welding the upper steel pipe column 10 and the lower steel pipe column 20. This allows the heat generated during welding to the upper steel pipe column 10 and the lower steel pipe column 20 to be applied symmetrically across the central axis of the steel pipe column 1. As a result, distortion of the central axis of the steel pipe column 1 can be suppressed.

[0043] In this embodiment, the articulated robot 80 in welding process S7 is controlled by a control device (not shown) for the articulated robot 80. Welding conditions, robot movements, etc., are stored in a program beforehand, and the welding sections between jigs 1L, 1R, ... divided by the operator are input to the control device. This allows a series of operations in welding process S7 to be performed automatically.

[0044] In the first welding step S4 and the second welding step S6 described later, as shown in Figure 5(a), molten welding material is supplied from diagonally above the groove 30 by the torch 92. Also, as shown in Figure 5(b), welding is performed using the backward method while tilting the torch 92 toward the rear in the direction of movement D of the torch 92 (welding is performed at a backward angle α). If necessary, as shown in Figure 5(c), welding is performed using the forward method while tilting the torch 92 toward the front in the direction of movement D of the torch 92 (welding is performed at an forward angle β).

[0045] In this embodiment, when welding the upper steel pipe column 10 and the lower steel pipe column 20 between the erection jigs 3, 3 that are temporarily fixed along the circumferential direction of the steel pipe column 1 is performed by an articulated robot 80, the welding sections 1R, 1L, 2R, and 2L between each jig between one erection jig 3 and the other erection jig 3 are divided into the following first to third welding sections Pa to Pc, and welding is performed accordingly.

[0046] As shown in Figures 4, 6, and 7, in the first welding section Pa, the torch 92 is tilted toward the rear in the direction of movement D of the torch 92 from a position where one of the erection jigs 3 is facing the other. In this state, welding is performed while decreasing the tilt angle (reverse angle) α of the torch with respect to the normal direction of the surface of the steel pipe column 1 as the torch 92 moves. Here, at the starting point of the first welding section Pa, it is sufficient that a stable quality weld can be performed without the torch 92 mechanically interfering with one of the erection jigs 3. Preferably, the tilt angle (reverse angle) of the torch 92 at the starting point of the first welding section Pa is in the range of 30° to 45°, and the tilt angle (reverse angle) at the ending point of the first welding section Pa is in the range of 5° to 25°. Within these ranges, welding is performed while decreasing the reverse angle from the starting point to the ending point of the first welding section Pa. For example, in the first welding section Pa, the tilt angle (retraction angle) α of the torch 92 is changed from 45° to 10°.

[0047] This allows for stable welding of the welding material, molten at a retraction angle α, to the groove 30 located opposite one of the alignment jigs 3. Furthermore, the tilt angle of the torch 92 can be changed up to the position in the second welding section Pb, described later, while avoiding contact between one of the alignment jigs 3 and the torch 92.

[0048] The second welding section Pb is continuous with the first welding section Pa. In the second welding section Pb, the inclination angle (retraction angle) α of the torch 92 at the end of the first welding section Pa is maintained, and welding is performed while inclining the torch 92 toward the rear in the direction of movement D of the torch 92. The second welding section Pb includes an R-shaped corner 10b (20b) connecting it to the flat section 10a (20a) of the steel pipe column 1. The normal direction of the surface of the R-shaped corner 10b (20b) is the direction perpendicular to the surface of the R-shaped corner 10b (20b) in the cross-section of the steel pipe column 1 along the horizontal direction. Here, the retraction angle of the second welding section Pb is preferably in the range of 5° to 25°, for example, 10°. This allows molten welding material to be supplied to the groove 30 at a constant retraction angle β in the second welding section Pb as well, enabling stable welding.

[0049] Thus, in the first and second welding sections Pa and Pb, welding is performed while tilting the torch 92 so that it faces backward in the direction of movement of the torch 92 (i.e., welding is performed using the back-reverse method). In this back-reverse method, the molten welding material does not precede the arc, and the molten welding material is pushed upward in the direction of movement D of the torch 92. As a result, the molten welding material penetrates more easily into the groove 30, and stable welding can be performed more reliably.

[0050] Because the R-shaped corner 10b (20b) of the steel pipe column 1 has a curved surface, it is difficult to form a stable bead 36 with the molten welding material. However, welding can be performed by tilting the torch 92 toward the rear in the direction of movement D of the torch 92 at a constant retraction angle α. This allows welding to be performed while stably supplying molten welding material to the groove 30 at the R-shaped corner 10b (20b) of the steel pipe column 1.

[0051] Furthermore, the third welding section Pc is continuous with the second welding section Pb. In the third welding section Pc, the inclination of the torch 92 is changed from the inclination angle (reverse angle) β of the torch 92 at the end of the second welding section Pb toward the forward direction in the direction of movement of the torch 92. Specifically, welding is performed until the other erection jig 3 is opposed, while further increasing the inclination angle (advancing angle) β with respect to the normal direction of the surface of the steel pipe column 1. Here, the angle at the start of the third welding section Pc is maintained at the angle at the end of the second welding section Pc, and the angle at the end of the third welding section Pc is sufficient if the torch 92 does not mechanically interfere with the other erection jig 3 and a stable quality weld can be performed. For example, the inclination angle (retraction angle) α of the torch 92 at the starting point of the third welding section Pc is preferably in the range of 5° to 25°, and the inclination angle (advance angle) β at the ending point of the third welding section Pc is preferably in the range of 30° to 45°. Within these ranges, welding is performed by changing the retraction angle of the torch 92 to an advance angle from the starting point to the ending point of the third welding section Pc, and then continuing to increase the advance angle.

[0052] This allows welding to be performed up to the opposing position of the other erection jig 3 while further increasing the inclination angle (advance angle) β with respect to the normal direction of the surface of the steel pipe column 1, thus avoiding contact between the torch 92 and the other erection jig 3.

[0053] In this embodiment, after welding the inter-jig welding section 1R using the articulated robot 80, the posture of the articulated robot 80 is changed, and welding is continued in the inter-jig welding section 1L. In the inter-jig welding section 1R, the first welding sections Pa to Pc are set and welding is performed. This is considered the first pass of welding. In the second pass, in the inter-jig welding section 1L, the first welding sections Pa to Pc are set sequentially starting from the erection jig 3 at the boundary and welding is performed. Subsequently, in the inter-jig welding section 1R, the first welding sections Pa to Pc are set sequentially starting from the erection jig 3 facing the rail 73 and welding is performed. Welding is repeated multiple times, moving back and forth between these sections. Therefore, the third welding section Pc, which was welded using the forward method in the previous pass, becomes the first welding section Pa, which is welded using the backward method in the subsequent pass, thus enabling stable welding.

[0054] 5. Regarding the removal process S5 In removal process S5, welding is performed multiple times in the welding section around the entire circumference of the steel pipe column, and then the erection jig 3 is removed from the steel pipe column 1. At this time, the erection pieces 11 and 21 may be cut from the steel pipe column 1.

[0055] 6. Regarding the second welding process S6 After the removal process S5, the second welding process S6 is performed. In this process, in the welding sections 1T and 2T to be welded by each articulated robot 80, welding is performed while tilting the torch 92 toward the rear in the direction of movement of the torch 92, excluding at least the welding start section and the welding end section.

[0056] In this process, as shown in Figure 8, welding is performed between the upper steel pipe column 10 and the lower steel pipe column 20 in welding sections 1T and 2T, in the same manner as in the first welding process S4, in the first to third welding sections Pa to Pc. In this process, welding is performed in the set first to third welding sections Pa to Pc while moving the torch 92 back and forth in each of welding sections 1T and 2T. In the example in Figure 8, the forward welding is shown, and in the case of the return welding, these sections are set in reverse. In this embodiment, welding is performed with the first to third welding sections Pa to Pc set, but welding may be performed with a constant retraction angle α for all of welding sections 1T and 2T.

[0057] In this process, even after the erection jig 3 is removed from the steel pipe column 1, stable welding can be performed by each articulated robot 80 in the welding sections 1T and 2T, excluding at least the welding start section (e.g., the first welding section Pa) and the welding end section (e.g., the third welding section Pc), by tilting the torch 92 toward the rear in the direction of movement D of the torch 92. Furthermore, although the position where the erection jig 3, which was positioned opposite the rail 73, was removed has welded sections formed by the backward and forward methods, after the erection jig 3 is removed, welding can be performed multiple times at this position at a constant backward angle α.

[0058] Figure 9 is a schematic perspective view illustrating a modified example of a welding method for a steel pipe column 1. In this modified example, during the welding process, the upper steel pipe column 10 and the lower steel pipe column 20 are treated as one set, and welding is performed on multiple sets (two sets in Figure 10) of upper steel pipe columns 10 and lower steel pipe columns 20 that are arranged in one direction along the horizontal.

[0059] In the rail installation process S2, as shown in Figure 9, a pair of rails 73 are attached to the lower steel pipe columns 20 so as to sandwich each of the two sets of upper steel pipe columns 10 and lower steel pipe columns 20. In the first and second welding processes S4 and S6, the articulated robots 80 are moved along the rails 73, and welding of the upper steel pipe columns 10 and lower steel pipe columns 20 in each set is performed sequentially and continuously.

[0060] In this modified version, a pair of articulated robots 80, 80 can be driven along the rail 73, allowing for continuous and sequential welding of adjacent upper steel pipe columns 10 and lower steel pipe columns 20. This eliminates the need to install rails for the robots to travel around each set of upper or lower steel pipe columns 10, as in the conventional method, and allows for the continuous and sequential welding of multiple steel pipe columns 1.

[0061] Furthermore, in the rail installation process S2, as shown in Figure 10, a pair of rails 73A and 73B, each consisting of a straight section 73a and a curved section 73b, may be attached to the lower steel pipe columns 20 of multiple sets of upper steel pipe columns 10 and lower steel pipe columns 20 arranged on the same floor, so as to sandwich each lower steel pipe column 20. Next, in the first and second welding processes S4 and S6, the articulated robots 80 are made to run along the rails 73A and 73B, and welding is performed sequentially between the upper steel pipe columns 10 and lower steel pipe columns 20 of each set. Here, multiple articulated robots 80 may be placed on each rail 73A (73B), and welding may be performed by multiple articulated robots 80.

[0062] Although one embodiment of the present invention has been described in detail above, the present invention is not limited to the above-described embodiment, and various design modifications can be made without departing from the spirit of the invention as described in the claims. [Explanation of symbols]

[0063] 1: Steel pipe column, 3: Erection jig, 10: Upper steel pipe column, 11: Erection piece, 20: Lower steel pipe column, 21: Erection piece, 30: Groove, 80: Welding robot (articulated robot), 92: Torch, 1L, 1R, 2R, 2L: Welding section between jigs, Pa: First welding section, Pb: Second welding section, Pc: Third welding section

Claims

1. A welding method for steel pipe columns, comprising: welding the upper steel pipe column and the lower steel pipe column, which are temporarily fixed by connecting erection pieces with a jig, by moving a torch attached to a welding robot along the groove while supplying molten welding material from the tip of the torch; The welding method involves welding the upper steel pipe column and the lower steel pipe column between erection jigs that are temporarily fixed along the circumferential direction of the steel pipe column, using the welding robot. The welding section between one erection jig and the other erection jig is, A first welding section in which welding is performed with the torch tilted toward the rear in the direction of movement of the torch from a position where one of the aforementioned erection jigs is facing the other, and as the torch moves, the tilt angle of the torch with respect to the normal direction of the surface of the steel pipe column decreases, A second welding section is continuous with the first welding section, maintaining the inclination angle of the torch at the end of the first welding section, and performing welding while tilting the torch toward the rear in the direction of movement of the torch, A third welding section, which is continuous with the second welding section, is performed while changing the inclination of the torch from the inclination angle of the torch at the end of the second welding section toward the forward direction in the direction of movement of the torch, and further increasing the inclination angle with respect to the normal direction of the surface of the steel pipe column, until the other erection jig is facing it, It has, The welding robot is an articulated robot, Prior to the welding, the process includes attaching a pair of rails to the lower steel pipe column so as to sandwich the lower steel pipe column, In the welding process described above, the articulated robot is moved along the rail while welding is performed between the upper steel pipe column and the lower steel pipe column. A method for welding a steel pipe column, characterized by repeating welding multiple times so as to move back and forth between the welding section between the jigs over the entire circumference of the steel pipe column.

2. The method for welding a steel pipe column according to claim 1, characterized in that the steel pipe column is a rectangular steel pipe column, the erection jig is installed on the flat surface, and the second welding section includes an R-shaped corner connecting to the flat surface of the steel pipe column.

3. In the first welding section, the tilt angle of the torch is reduced linearly in accordance with the amount of movement of the torch. The method for welding a steel pipe column according to claim 1 or 2, characterized in that, in the third welding section, the inclination angle of the torch is increased linearly in accordance with the amount of movement of the torch.

4. After welding is performed multiple times in the inter-jig welding section over the entire circumference of the steel pipe column, Remove the erection jig from the steel pipe column. A method for welding steel pipe columns according to any one of claims 1 to 3, characterized in that, in the welding sections to be welded by each articulated robot, welding is performed while tilting the torch toward the rear in the direction of movement of the torch in at least the sections excluding the welding start section and the welding end section.

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