How to weld steel pipe columns

Abstract

To provide a welding method for steel stand columns enabling stable-quality welding of upper and lower steel stand columns to be more easily performed.SOLUTION: A welding method for steel stand columns includes at least: a clearance measuring step S4 of measuring a clearance S between upper and lower steel stand columns 10 and 20 along the circumferential direction of the columns 10 and 20, the clearance forming a bevel 30 ; an interval splitting step S5 of splitting the bevel 30 revolving along a circumferential direction according to the range of a measured clearance magnitude into a plurality of welding intervals; a welding condition setting step S6 of setting the welding condition for each welding interval according to the pre-decided welding condition for each range of magnitude of the clearance S; and a welding step S7 of performing the welding operation of the upper columns 10 and lower steel stand 20 using an articulated robot 80 under the welding condition set for each welding interval.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a steel pipe pole welding method for welding an upper steel pipe pole to a lower steel pipe pole. [Background technology]

[0002] As an example of this type of technology, Patent Document 1 proposes a method for welding steel pipe columns in which an upper steel pipe column and a lower steel pipe column are welded together while supplying molten welding material to the groove between the upper steel pipe column and the lower steel pipe column.

[0003] Specifically, the upper steel pipe column and the lower steel pipe column, which are temporarily fixed by connecting the erection piece with a plumbing jig, are initially welded in multiple layers by a welding robot, and the plumbing jig is of After removal, the remaining layers are welded using a welding robot. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6315896 Summary of the Invention [Problem to be solved by the invention]

[0005] However, by adjusting the perpendicularity of the upper steel pipe column and the lower steel pipe column, the size of the groove formed by the upper steel pipe column and the lower steel pipe column may change along the circumferential direction. In such a case, if the upper steel pipe column and the lower steel pipe column are welded using the welding method shown in Patent Document 1, welding will be performed under the same welding conditions at the location where the groove is large and at the location where the groove is small, and it is difficult to achieve welding of stable quality along the circumferential direction of the steel pipe column.

[0006] The present invention has been made in consideration of these points, and an object of the present invention is to provide a method for welding steel pipe columns that can more easily perform welding of stable quality between an upper steel pipe column and a lower steel pipe column, even when the size of the groove formed by the upper steel pipe column and the lower steel pipe column changes along the circumferential direction. [Means for solving the problem]

[0007] In view of the above problems, the welding method for steel pipe columns according to the present invention is a welding method for steel pipe columns in which the upper steel pipe column and the lower steel pipe column are welded while 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 an erection piece with a plumbing jig. The method includes at least a gap measurement process for measuring the gap between the upper steel pipe column and the lower steel pipe column that form the groove along the circumferential direction of the upper steel pipe column and the lower steel pipe column, a section division process for dividing the groove that goes around along the circumferential direction into a plurality of welding sections, a welding condition setting process for setting welding conditions for each welding section from welding conditions determined in advance for each range of the gap size and the range of the gap size measured for each welding section, and a welding process for welding the upper steel pipe column and the lower steel pipe column with the welding robot under the welding conditions set for each welding section.

[0008] According to the present invention, the welding conditions are determined in advance for each range of the size of the gap between the upper steel pipe column and the lower steel pipe column that form the groove, and the divided welding sections are welded in accordance with these welding conditions, so that the upper steel pipe column and the lower steel pipe column can be welded under simpler welding conditions. For example, when the measured gap (measurement gap) is constant, welding can be performed under the same welding conditions according to that constant measured gap, and when the measured gap changes, welding can be performed under welding conditions set for each range of the measured gap in that welding section.

[0009] In addition, when the upper steel pipe column and the lower steel pipe column are aligned vertically, the gap between the upper steel pipe column and the lower steel pipe column along the circumferential direction tends to be larger on one side of the axis and smaller on the other side. In such a case, the size of the gap changes continuously in the circumferential direction, so the size of the gap in the welded section also changes continuously in the circumferential direction. Therefore, for example, when dividing the groove into welded sections according to the range of the gap size, the divided sections can be easily set. When dividing the groove into pre-set welding sections (for example, between the erection pieces), the range of the gap size in the welded section is likely to fall within a predetermined range. As a result, the welding conditions for each divided welding section can be set, and stable welding between the upper steel pipe column and the lower steel pipe column can be performed more easily than before by a welding robot.

[0010] Here, in a preferred embodiment, in the section dividing step, the groove going around in the circumferential direction is divided into the plurality of weld sections according to a preset range of the size of the gap. According to this embodiment, since the criterion for dividing into the weld sections is based on the range of the size of the gap, better welding conditions can be set and the upper steel pipe column and the lower steel pipe column can be welded together.

[0011] Here, the above-mentioned welding robot may be, for example, a welding robot that runs on rails or a welding robot that only turns, so long as it can move the position of the torch tip of the welding machine to an appropriate position, and the form of the welding robot is not particularly limited. In a more preferred embodiment, the welding robot is an articulated robot, and includes, before the welding step, a rail mounting step of mounting a pair of rails to the lower steel pipe column so as to sandwich the lower steel pipe column, and in the welding step, welding is performed between the upper steel pipe column and the lower steel pipe column while the articulated robot is made to run along the rails.

[0012] According to this aspect, welding is performed between the upper steel pipe column and the lower steel pipe column while the articulated robot is running along the rail, so that welding can be performed while easily adjusting the distance and angle of the tip of the torch relative to the groove to the desired angle.

[0013] In a further preferred embodiment, the welding process involves welding multiple sets of the upper steel pipe column and the lower steel pipe column arranged in one direction along the horizontal direction, with the upper steel pipe column and the lower steel pipe column forming one set, and in the rail attachment process, the pair of rails are attached to the lower steel pipe column so as to sandwich each of the lower steel pipe columns for the multiple sets of the upper steel pipe column and the lower steel pipe column, and in the welding process, welding of the upper steel pipe column and the lower steel pipe column in each set is performed sequentially while traveling the articulated robot.

[0014] According to this embodiment, the welding of the upper steel pipe column and the lower steel pipe column of each adjacent pair can be performed continuously and sequentially while the articulated robot is traveling along the rail. This makes it possible to perform welding of a plurality of steel pipe columns in succession without the need for the conventional work of attaching rails for the robot to travel around the upper steel pipe column or the lower steel pipe column for each pair.

[0015] In a further preferred embodiment, in the welding process, welding of the upper steel pipe column and the lower steel pipe column is performed by a pair of the multi-joint robots, and in the welding process, welding of the upper steel pipe column and the lower steel pipe column is performed while facing the tips of the torches of the pair of multi-joint robots across the central axis of the steel pipe column.

[0016] According to this embodiment, the upper steel pipe column and the lower steel pipe column are welded while the tips of the torches of the pair of articulated robots are opposed to each other across the central axis of the steel pipe column, so that the heat during welding to the upper steel pipe column and the lower steel pipe column can be input symmetrically across the central axis of the steel pipe column, thereby suppressing distortion of the central axis of the steel pipe column. Effect of the Invention

[0017] According to the present invention, even if the size of the groove formed by the upper steel pipe column and the lower steel pipe column changes along the circumferential direction, welding of the upper steel pipe column and the lower steel pipe column with stable quality can be performed more easily. [Brief description of the drawings]

[0018] [Figure 1] FIG. 2 is a flow chart for explaining a welding method for a steel pipe column according to an embodiment of the present invention. [Diagram 2] FIG. 11 is a side view illustrating a temporary fixing step. [Diagram 3] FIG. 11 is a schematic perspective view for explaining a rail mounting step and a robot installation step. [Figure 4] 5(a) to 5(c) are schematic cross-sectional views for explaining a gap measuring step. [Diagram 5] FIG. 10A is a diagram for explaining a section dividing step, and FIG. 10B is a diagram for explaining a welding condition setting step. [Figure 6] FIG. 13 is a diagram for explaining a section division step according to a modified example. [Figure 7] FIG. 13A is a diagram for explaining a section dividing step according to another modified example, and FIG. 13B is a diagram for explaining a welding condition setting step according to another modified example. [Figure 8] 5(a) to 5(c) are schematic cross-sectional views illustrating a welding process. [Figure 9] FIG. 2 is a schematic conceptual diagram for explaining welding of multi-layer buildup in a welding process. [Figure 10] FIG. 11 is a schematic perspective view for explaining a welding method for a steel pipe pole according to a modified example. [Figure 11] FIG. 11 is a schematic perspective view for explaining a welding method for a steel pipe pole according to a further modified example shown in FIG. 10. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Hereinafter, a welding method for a steel pipe pole according to an embodiment of the present invention will be described with reference to the drawings.

[0020] Fig. 1 is a flow diagram for explaining a welding method for a steel pipe column 1 according to an embodiment of the present invention. Hereinafter, as the welding method in this embodiment, each step from the temporary fixing step S1 to the welding step S7 shown in Fig. 1 will be described in detail.

[0021] 1. Regarding the temporary fixing process S1, In the embodiment, first, a temporary fixing step S1 is performed. As shown in Fig. 2, in the temporary fixing step S1, the upper steel pipe column 10 and the lower steel pipe column 20 are temporarily fixed by a plumbing jig 3, and then the inclination of the upper steel pipe column 10 is adjusted.

[0022] Here, the upper steel pipe column 10 and the lower steel pipe column 20 are made of polygonal steel pipes formed by four flat portions and four curved portions, and erection pieces 11, 21 are attached to the flat portions of the upper steel pipe column 10 and the lower steel pipe column 20, respectively. 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 Figs. 2 and 3 and the like, and may be, for example, rectangular steel pipe columns of a polygon other than a rectangle (specifically, a polygonal steel pipe with four or more sides), or may be a multi-sided box column such as a four-sided box column.

[0023] The lower end edge surface 13 of the upper steel pipe column 10 is a tapered surface inclined outward, and the upper end edge surface 23 of the lower steel pipe column 20 is a flat surface formed so as to be 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 disposed so as to face 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.

[0024] Furthermore, in this embodiment, a backing metal 31 is attached along the circumferential direction to the inner wall surface of the lower steel pipe column 20. The backing metal 31 protrudes in the vertical direction (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 disposed on the lower steel pipe column 20, the protruding portion of the backing metal 31 is inserted into the upper steel pipe column 10.

[0025] As described later, such a backing metal 31 can cover the gap between the upper steel pipe column 10 and the lower steel pipe column 20 when the inclination of the upper steel pipe column 10 is adjusted, so that it is possible to prevent the molten welding material from penetrating into the steel pipe column 1 during welding. Note that in this embodiment, the backing metal 31 is attached to the inner wall surface of the lower steel pipe column 20, but the backing metal may also 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, for example.

[0026] 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 metal 31 is inserted into the upper steel pipe column 10. The upper end of the plumbing jig 3 is fastened to the erection piece 11 using a bolt or the like, and the lower end of the plumbing jig 3 is fastened to the erection piece 21 using a bolt or the like. As a result, the erection pieces 11, 21 of the upper steel pipe column 10 and the lower steel pipe column 20 are connected to each other by the plumbing jig 3, and the upper steel pipe column 10 and the lower steel pipe column 20 can be temporarily fixed.

[0027] Next, the inclination of the upper steel pipe column 10 arranged above the lower steel pipe column 20 is adjusted. This adjusts the verticality of the upper steel pipe column 10 and the lower steel pipe column 20, and allows the upper steel pipe column 10 and the lower steel pipe column 20 to be aligned. Note that, as shown in parts A and B of FIG. 2, the size of the gaps Da and Db between the upper steel pipe column 10 and the lower steel pipe column 20 forming the groove 30 may change in the circumferential direction due to installation errors of the lower steel pipe column 20 and the lower steel pipe column 20, dimensional tolerances of the lower steel pipe column 20 and the lower steel pipe column 20, etc. Specifically, the gap along the circumferential direction between the upper steel pipe column 10 and the lower steel pipe column 20 becomes larger on one side with respect to the axis and smaller on the other side, and the size of the gap changes inclinedly between them.

[0028] Here, detailed description of the structure of the plumbing jig 3 will be omitted, but each plumbing jig 3 is configured to be able to adjust the distance between the two erection pieces 11, 21 arranged above and below. As a result, as shown in FIG. 2, it is possible to adjust the gap between the upper steel pipe column 10 and the lower steel pipe column 20 arranged above and below, and it is also possible to adjust the inclination of the upper steel pipe column 10 arranged on the upper side. After or during the welding process 7 described below, in the removal process S8, the plumbing jig 3 is removed from the erection pieces 11, 21, and the erection pieces 11, 21 are cut from the upper steel pipe column 10 and the lower steel pipe column 20.

[0029] 2. Rail installation process S2 A rail attachment step S2 shown in Fig. 1 is performed. In this step, a pair of rails 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, 26 are welded to each of two flat surfaces located on opposite sides 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 a multi-joint robot (robot arm) 80 described later runs.

[0030] Next, a pair of second support members 72 are fixed across the pair of first support members 71 so as to sandwich the lower steel pipe column 20. The second support member 72 is a long member, and the rail 73 is attached to the second support member 72 along the longitudinal direction, so that the 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. Note that in this embodiment, the rail 73 is attached to the lower steel pipe column 20 using the first support member 71 and the second support member 72, but the rail 73 may be attached to the lower steel pipe column 20 as long as rigidity can be ensured, for example.

[0031] In this embodiment, the rail 73 is a linear guide rail, and a carriage (slider) 74 is attached to the rail 73. The carriage 74 is movable along the rail 73 by a motor (not shown). Note that in this embodiment, the travel control of the carriage 74, the drive control of the articulated robot 80 (described later), and welding according to the welding conditions using a 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.

[0032] 3. Robot installation process S3 1 is performed. In this step, the articulated robot 80 is installed on the carriage 74. The articulated robot 80 used in this embodiment is a robot that rotates on six axes, and is a welding robot connected to a welding machine.

[0033] The articulated robot 80 is a welding robot connected to a welding machine (not shown), and includes a base 82 attached to the cart 74, and a swivel base 83 placed on the base 82 and swivels relative to the base 82. A lower arm 84 is pivotally attached to the swivel base 83. A joint 85 is pivotally attached to the tip of the lower arm 84. An upper arm 86 is attached to the joint 85 so as to be rotatable about an axis extending in the longitudinal direction.

[0034] Furthermore, a support arm 87 that supports a torch 92 of a welding machine that serves as an end effector is attached to the tip of upper arm 86. A cable 91 that feeds a welding wire is connected to torch 92 of support arm 87 relative to upper arm 86, and a base end of cable 91 is connected to a feeding device (not shown) that feeds the welding wire.

[0035] In this embodiment, the rail mounting process S2 and the robot installation process S3 are performed before the gap measurement process S4 described later, but these processes may be performed at any time after the temporary fixing process S1 and before the welding process S7 described later.

[0036] 4. Regarding the gap measurement process S4 Next, a gap measurement process S4 shown in Fig. 1 is performed. In this process, the gap D between the upper steel pipe column 10 and the lower steel pipe column 20 that form the groove 30 is measured along the circumferential direction of the upper steel pipe column 10 and the lower steel pipe column 20.

[0037] In this embodiment, for example, as shown in Figures 4(a) to (c), in a groove 30 formed along the circumferential direction, the vertical distance between the lower end edge surface 13 of the upper steel pipe column 10 and the upper end edge surface 23 of the lower steel pipe column 20 is measured as the gap D. Here, the position at which the distance is measured is, for example, a gap at a position along the vertical inner wall surfaces 18, 28 of the upper steel pipe column 10 and the lower steel pipe column 20, as shown in Figures 4(a) to (c).

[0038] However, it is not limited to this, and may be, for example, the distance between the upper steel pipe column 10 and the lower steel pipe column 20 at positions along the outer wall surfaces 17, 27 in the vertical direction of the upper steel pipe column 10 and the lower steel pipe column 20. As long as the change in size of the groove 30 along the circumferential direction can be specified as a specific numerical value, the position at which the gap is measured is not particularly limited.

[0039] Note that, for example, the measurement of this gap D may be performed by an operator at predetermined intervals along the circumferential direction, or the gap may be measured continuously or intermittently along the circumferential direction of the upper steel pipe column 10 and the lower steel pipe column 20 by touch sensing using an articulated robot 80. The gap D (D1>D2>D3) between the upper steel pipe column 10 and the lower steel pipe column 20 that form the groove 30 becomes smaller in the order of Fig. 4(a) to Fig. 4(c), and the size of the groove 30 also becomes smaller in this order.

[0040] 5. Section division process S5 Next, a section division step S5 shown in Fig. 1 is performed. As shown in Fig. 5(a), in this step, (the welding line of) the groove 30 going around in the circumferential direction is divided into a plurality of 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.

[0041] In addition, for example, as shown in a modified example shown in Fig. 6, the weld line of the groove 30 may be divided into four sections according to the four flat portions of the upper steel pipe column 10 and the lower steel pipe column 20. Note that, although the weld line of the groove 30 is divided into four weld sections in this embodiment, the worker may divide the weld section into an appropriate number according to the ease of welding, changes in the gap, and the like.

[0042] 7(a), in the section dividing step S5, (the welding line of) the groove 30 going around in the circumferential direction may be divided into a plurality of welding sections s1 to s4 according to a preset gap size range (gap ranges A to C). In this modification, the welding line of the groove 30 is divided based on the result of the gap measured in the gap measuring step S4.

[0043] The gap range is, for example, the gap range A being the largest range compared to the other gap ranges B and C, the gap range B being the intermediate range between the gap range A and the gap range C, and the gap range C being the smallest range compared to the other gap ranges A and B. For example, the gap D1 shown in FIG. 4(a) is in the gap range A, the gap D2 shown in FIG. 4(b) is in the gap range B, and the gap D3 shown in FIG. 4(c) is in the gap range C. These gap ranges may overlap in part. In this case, when dividing the groove along the circumferential direction described later into welded sections, the gap may be divided, for example, at the center position of these overlapping gap ranges.

[0044] 6. Regarding welding condition setting process S6 Next, a welding condition setting step S6 shown in Fig. 1 is performed. As shown in Fig. 5(b), in this step, welding conditions d, c, ... are set for each welding section 1L, 1R, ... from welding conditions a, b, ... determined in advance for each gap size range Da-Db, Dc-Dd, ... and gap size ranges Da-Db, Dg-Dh, De-Df, Dc-Dd measured for each welding section 1L, 1R, ....

[0045] Specifically, in this embodiment, as shown in the table on the left of Fig. 5(b), welding conditions are set in advance for each gap range. The ranges of these gap ranges may overlap in part. For example, gap ranges Di to Dj may be included in part of gap ranges Da to Db. In this way, by determining in advance welding conditions a, b, ... corresponding to a plurality of gap ranges Da to Db, Dc to Dd, ..., it is possible to weld the upper steel pipe column 10 and the lower steel pipe column 20 under appropriate welding conditions according to the range of the gap in the welding section divided by the worker.

[0046] In this embodiment, the welding conditions for each of the welding sections 1L, 1R, ... are set as follows. Specifically, as shown in Fig. 5(a), when the measured minimum gap in the welding section 1L is Dg and the measured maximum gap is Dh, the gap range in the welding section 1L is Dg to Dh.

[0047] Therefore, from the relationship between the gap range and the welding conditions in Fig. 5(b) (left table), the welding conditions in this case correspond to condition d, so the welding conditions for welding section 1L are set to condition d (see right table). The welding conditions for the other welding sections 1R, 2L, and 2R can be set to conditions c, b, and a, respectively, by performing similar operations. Thus, in this embodiment, if welding conditions according to the gap range are set in advance in a finer range in Fig. 5(a), higher quality welding can be performed.

[0048] In the modified example shown in FIG. 7(a), as described above, in the section dividing step S5, the groove 30 (the welding line) going around in the circumferential direction is divided into a plurality of welding sections s1 to s4 according to a preset gap size range (gap range A to C). In this case, as shown in the left diagram of FIG. 7(b), conditions X to Z, which are welding conditions, are determined in advance for each of the gap ranges A to C. Therefore, the conditions X, Y, and Z shown in the right table can be set for each of the welding sections s1 to s4. In this modified example, the welding sections s1, s2, ... are divided according to the gap ranges A to B that are optimal for the predetermined welding conditions X to Z, so that stable welding can be performed with fewer welding conditions.

[0049] 7. Welding process S7 Next, a welding step S7 shown in Fig. 1 is performed. In this step, welding of the upper steel pipe column 10 and the lower steel pipe column 20 is performed by an articulated robot 80 under welding conditions set for each welding section. Here, Figs. 8(a) to (c) show the results of welding performed on the groove 30 of the upper steel pipe column 10 and the lower steel pipe column 20 shown in Figs. 4(a) to (c). In this embodiment, the welding conditions are set according to the size of the gap range, so that as the groove 30 becomes larger (i.e., the gap D becomes larger), as shown in Figs. 4(a) to (c), the welding material is supplied from the tip of the torch 92 so that the welded portions 36A to 36C become larger.

[0050] Here, each welding is performed according to the above-mentioned welding conditions. Specifically, when the amount of welding material to be supplied is increased, the articulated robot 80 is controlled to (1) increase the wire feed speed, (2) decrease the movement speed of the torch 92, or perform both (1) and (2). In the case of (1), the applied voltage or current flowing through the torch 92 is increased. On the other hand, when the amount of welding material to be supplied is decreased, the articulated robot 80 is controlled so that the operation of the welding wire feed speed or the movement speed of the torch 92 is the opposite to that when the amount of welding material to be supplied is increased.

[0051] In this embodiment, as shown in Figs. 5(a), 6, and 7(a), each articulated robot (welding robot) 80 is set to perform welding in areas A and B, which are defined by a boundary line separating the space between the opposing rails 73 and 73. When welding is performed by each articulated robot 80 in the set areas A and B, the torch 92 is moved along the welding line of the groove 30, and the welding material is supplied from the tip of the torch 92 to the groove 30. When welding is performed for each welding section shown in Fig. 5(a), the welding is temporarily interrupted when the articulated robot 80 passes through the erection pieces 11 and 21 at the boundary between the welding sections, and the welding conditions are changed, so that the welding can be performed more smoothly. In addition, when the welding is interrupted, the torch 92 and the like can be automatically cleaned.

[0052] Here, the torch 92 may be moved multiple times along the weld line of the groove 30 while supplying the welding material to form a welded portion 36 that will be a multi-layer build-up portion, as shown in FIG. 9. As shown in FIG. 9, in this case, the position of the welding point at the tip of the torch 92 and the direction of the torch differ with each movement, so that when performing such welding, it is suitable to perform the welding using an articulated robot. Also, it is preferable that the number of times that the torch 92 is moved and the welding material is built up is the same in each welding section. This can prevent steps from being formed in the welded portion (bead).

[0053] In this embodiment, welding is performed between the upper steel pipe column 10 and the lower steel pipe column 20 while the tips of the torches 92 of a pair of articulated robots 80, 80 are opposed to each other across the central axis of the steel pipe column 1. This makes it possible to input heat during welding to the upper steel pipe column 10 and the lower steel pipe column 20 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, etc. can be suppressed.

[0054] In the embodiment, the control of the articulated robot 80 in the welding step S7 is performed by a control device (not shown) of the articulated robot 80, and the welding conditions, the robot's operation, etc. are stored in a program in advance, and the welding sections divided by the worker are input to the control device. This allows a series of operations in the welding step S7 to be performed automatically.

[0055] FIG. 10 is a schematic perspective view for explaining a welding method for a steel pipe pole 1 according to a modified example. In this modified example, in the welding process, an upper steel pipe column 10 and a lower steel pipe column 20 are considered as one set, and multiple sets (two sets in Figure 10) of upper steel pipe columns 10 and lower steel pipe columns 20 arranged in one direction along the horizontal direction are welded.

[0056] In the rail attachment process S2, as shown in Fig. 10, a pair of rails 73 are attached to the lower steel pipe columns 20 of two sets of upper steel pipe columns 10 and lower steel pipe columns 20 so as to sandwich each lower steel pipe column 20. In the welding process S7, while each articulated robot 80 is made to travel along the rails 73, welding of the upper steel pipe columns 10 and the lower steel pipe columns 20 in each set is performed sequentially and continuously.

[0057] In this modified example, welding of adjacent pairs of upper steel pipe columns 10 and lower steel pipe columns 20 can be continuously performed in sequence while a pair of articulated robots 80, 80 is made to travel along the rails 73. This makes it possible to eliminate the need for work such as attaching rails for running the robot so that it circles around the upper steel pipe column 10 or the lower steel pipe column 20 for each pair, as in the conventional method, and allows welding of a plurality of steel pipe columns 1 in sequence.

[0058] Furthermore, in the rail attachment step S2, as shown in Fig. 11, a pair of rails 73A, 73B combining a straight portion 73a and a curved portion 73b may be attached to the lower steel pipe column 20 so as to sandwich each lower steel pipe column 20 for a plurality of sets of upper steel pipe columns 10 and lower steel pipe columns 20 arranged on the same floor. Next, in the welding step S7, welding between the upper steel pipe column 10 and the lower steel pipe column 20 in each set is sequentially performed while each articulated robot 80 is made to travel along the rails 73A, 73B. Here, a plurality of articulated robots 80 may be arranged on each rail 73A (73B), and welding may be performed by the plurality of articulated robots 80.

[0059] Although one embodiment of the present invention has been described in detail above, the present invention is not limited to the above embodiment, and various design modifications can be made without departing from the spirit of the present invention described in the claims. [Explanation of symbols]

[0060] 1: Steel pipe column, 3: Plumbing 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, S2: Rail installation process, S4: Gap measurement process, S5: Section division process, S6 Welding condition setting process, S7 Welding process

Claims

1. A method for welding a steel pipe column in which the upper steel pipe column and the lower steel pipe column are welded while 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 plumbing jig, A gap measurement process for measuring a gap between the upper steel pipe column and the lower steel pipe column that form the groove along the circumferential direction of the upper steel pipe column and the lower steel pipe column; A section dividing process of dividing the groove that goes around the circumferential direction into a plurality of welding sections; a welding condition setting step of setting welding conditions for each welding section based on the welding conditions previously determined for each range of the gap size and the range of the gap size measured for each welding section; a welding process in which the upper steel pipe column and the lower steel pipe column are welded together by the welding robot under welding conditions set for each welding section; At least A method for welding a steel pipe column, characterized in that, in the section division step, the groove going around the circumferential direction is divided into the plurality of weld sections according to a preset range of the size of the gap.

2. The welding robot is an articulated robot, A rail mounting process is included in which a pair of rails are mounted to the lower steel pipe column so as to sandwich the lower steel pipe column before the welding process, The method for welding steel pipe columns according to claim 1, characterized in that, in the welding step, the upper steel pipe column and the lower steel pipe column are welded together while the articulated robot is made to travel along the rail.

3. The welding process includes welding a plurality of sets of the upper steel pipe column and the lower steel pipe column arranged in one direction along a horizontal direction, with the upper steel pipe column and the lower steel pipe column being one set, In the rail mounting step, the pair of rails are mounted to the lower steel pipe columns so as to sandwich each lower steel pipe column with respect to the plurality of sets of the upper steel pipe columns and the lower steel pipe columns, The method for welding steel pipe columns according to claim 2, characterized in that, in the welding step, welding of the upper steel pipe column and the lower steel pipe column in each set is performed sequentially while the articulated robot is traveling.

4. In the welding process, welding of the upper steel pipe column and the lower steel pipe column is performed by a pair of the articulated robots, The method for welding steel pipe columns according to claim 2 or 3, characterized in that, in the welding process, the upper steel pipe column and the lower steel pipe column are welded together while the tips of the torches of the pair of articulated robots are opposed to each other across the central axis of the steel pipe column.

Images