JP2019155409A - Steel pipe welding method and column construction method - Google Patents

Abstract

To provide a steel pipe welding method which enables a lower steel pipe to provide a well-balanced support to an upper steel pipe even when a temporarily fixing means such as an erection piece is withdrawn.SOLUTION: A method for welding polygonal section steel pipes 1, 2 having a plurality of corners 1a, 2a and a plurality of sides 1b, 2b with each other in a state of being abutted vertically includes: a corner weld zone forming step of forming a plurality of corner weld zones 10 by welding the lower end of each corner 1a of the upper steel pipe 1 with the upper end of each corner 2a of the lower steel pipe 2; and a side weld zone forming step of forming a plurality of side weld zones 20 by welding the lower end of each side 1b of the steel pipe 1 with the upper end of each side 2b of the steel pipe 2 after the corner weld zone forming step. In the corner weld zone forming step, the lower end of each corner 1a of the steel pipe 1 is welded with the upper end of each corner 2a of the steel pipe 2 by semi-automatic welding. In the side weld zone forming step, the lower end of each side 1b of the steel pipe 1 is welded with the upper end of each side 2b of the steel pipe 2 by automatic welding.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a method for welding steel pipes in a state where the steel pipes are butted against each other, and a method for constructing a column.

  Patent document 1 is disclosing the method of welding each other in the state which faced up and down the steel pipes of a square cross section which has four corner | angular parts and four side parts. In Patent Document 1, first, the lower ends of the two sides of the upper steel pipe and the upper ends of the two sides of the lower steel pipe are welded. Next, in order to temporarily fix the upper steel pipe and the lower steel pipe to each other, the erection piece provided in advance on these steel pipes is removed. Next, the lower ends of the remaining two sides of the upper steel pipe and the upper ends of the remaining two sides of the lower steel pipe are welded, and the lower ends of the four corners of the upper steel pipe and the lower The upper ends of the four corners of the side steel pipe are welded.

Japanese Patent Laid-Open No. 06-198442

  However, in the technique disclosed in Patent Document 1, since the erection piece is removed only by welding the lower ends of the two sides of the upper steel pipe and the upper ends of the two sides of the lower steel pipe, After removal of this erection piece, it was difficult for the lower steel pipe to support the upper steel pipe in a well-balanced manner.

  In view of such a situation, an object of the present invention is to provide a steel pipe welding method in which a lower steel pipe can support an upper steel pipe in a well-balanced manner even after a temporary fixing means such as an erection piece is removed.

Therefore, the welding method of the steel pipe which concerns on this invention is a method of welding each other in the state which faced up and down the polygonal-section steel pipe which has a some corner | angular part and a some side part. The steel pipe welding method according to the present invention is a method for forming a plurality of corner welds by welding a lower end portion of each corner portion of the upper steel pipe and an upper end portion of each corner portion of the lower steel pipe. Side welded part that forms a plurality of side welded parts by welding the lower end part of each side part of the upper steel pipe and the upper end part of each side part of the lower steel pipe after the step and the corner welded part forming step Forming step. In the side welded portion forming step, the lower end portion of each side portion of the upper steel pipe and the upper end portion of each side portion of the lower steel pipe are welded by automatic welding.
The column construction method according to the present invention includes the above-described steel pipe welding method.

  According to the present invention, after forming a plurality of corner welds by welding the lower end of each corner of the upper steel pipe and the upper end of each corner of the lower steel pipe, each side of the upper steel pipe A plurality of side welds are formed by welding the lower end of the part and the upper end of each side of the lower steel pipe. Therefore, for example, after forming a plurality of corner welds, the temporary fixing means such as the aforementioned erection piece can be removed, and after removing the temporary fixing means, a plurality of side welds can be formed. Moreover, since each of the upper steel pipe and the lower steel pipe has a polygonal cross section, the plurality of corner welds are three or more corner welds. Therefore, even after the above-described temporary fixing means is removed, the lower steel pipe can support the upper steel pipe in a well-balanced manner through three or more corner welds.

The front view of the upper steel pipe and lower steel pipe which were temporarily fixed mutually by temporary fixing means in one embodiment of the present invention. Sectional drawing of the upper steel pipe and sectional drawing of the lower steel pipe in the one embodiment The figure which shows the welding method with the upper steel pipe and lower steel pipe in the said one Embodiment. The figure which shows the welding method with the upper steel pipe and lower steel pipe in the said one Embodiment. The figure which shows the welding method with the upper steel pipe and lower steel pipe in the said one Embodiment. The figure which shows the welding method of the upper steel pipe in the modification of the said one embodiment, and a lower steel pipe The figure which shows schematic structure of the automatic welding apparatus in the said one Embodiment. The figure which shows the formation method of the side welding part in the said one Embodiment. The figure which shows the formation method of the side welding part in the said one Embodiment. The figure which shows the back step process and main welding process at the time of the side weld part formation in the said embodiment. The figure which shows the welding conditions of the main welding process at the time of edge | side weld part formation in the said one Embodiment, and the welding conditions of a back step process.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a front view of an upper steel pipe and a lower steel pipe temporarily fixed to each other by temporary fixing means in an embodiment of the present invention. FIG. 2A is a cross-sectional view of the upper steel pipe. FIG. 2A is a cross-sectional view of the lower steel pipe. For convenience of explanation, as shown in FIG. 1 and FIG.

  In this embodiment, when a column is constructed by welding (connecting) column steel members at a construction site when constructing a steel structure, the steel pipe welding method and the column constructing method according to the present invention are applied. An example will be described. However, application examples of the steel pipe welding method and the column construction method according to the present invention are not limited thereto.

Each of the upper steel pipe 1 and the lower steel pipe 2 shown in FIGS. 1 and 2 corresponds to the above-described column steel member. Each of the steel pipes 1 and 2 extends in the vertical direction. The column 100 includes steel pipes 1 and 2.
The steel pipes 1 and 2 have a polygonal cross section having a plurality of corner portions 1a and 2a and a plurality of side portions 1b and 2b. In the present embodiment, the steel pipes 1 and 2 are so-called square steel pipes, which will be described below as having a square cross section having four corners 1a and 2a and four sides 1b and 2b. The cross-sectional shape is not limited to a quadrangle, and may be a triangle, pentagon, hexagon, heptagon, octagon, or the like. The polygon of the cross-sectional shape of the steel pipes 1 and 2 is preferably any one of a triangle, a rectangle, a pentagon, a hexagon, a heptagon, and an octagon, and more preferably a rectangle. Moreover, although the example whose cross-sectional shape of the steel pipes 1 and 2 is square is illustrated by FIG.1 and FIG.2, a cross-sectional shape may be a rectangle in addition to this.

  The corner portions 1a and 2a of the steel pipes 1 and 2 correspond to the above-described polygonal “corners”. The corners 1a and 2a of the steel pipes 1 and 2 are rounded. Therefore, the cross-sectional shapes of the corner portions 1a and 2a of the steel pipes 1 and 2 are arc-shaped, and the outer surface (the surface on the side constituting the outer peripheral surface of the steel pipes 1 and 2) and the inner surface (the inner peripheral surface of the steel pipes 1 and 2). Each side surface is a curved surface.

  The side parts 1b and 2b of the steel pipes 1 and 2 correspond to the above-described polygonal "sides". The cross-sectional shapes of the side portions 1b and 2b of the steel pipes 1 and 2 are linear, and the outer surface (the surface on the side constituting the outer peripheral surface of the steel pipes 1 and 2) and the inner surface (the side constituting the inner peripheral surface of the steel pipes 1 and 2). Are planes. In addition, the one side parts 1b and 2b of the steel pipes 1 and 2 are located between the two corners 1a and 2a. In other words, one side 1b, 2b of the steel pipes 1, 2 is sandwiched between two corners 1a, 2a.

  In the present embodiment, the pillar 100 is constructed by welding the steel pipes 1 and 2 to each other in a state where the steel pipes 1 and 2 are butted together (state shown in FIG. 1). For this reason, the backing material 4 is attached to the inner peripheral surface of the upper end part of the steel pipe 2 over the entire circumference before the steel pipes 1 and 2 are abutted up and down. When the steel pipes 1 and 2 are butted together, the upper end portion of the backing material 4 overlaps the inner peripheral surface of the lower end portion of the steel pipe 1. In addition, the taper surface 5 is formed in the lower end part of the steel pipe 1 so that it may go inside the steel pipe 1 as it goes below.

Next, a method of welding the steel pipes 1 and 2 to each other will be described with reference to FIGS. 3 to 5 in addition to FIGS. 1 and 2 described above.
3-5 is a figure which shows the welding method of the steel pipes 1 and 2 in this embodiment. Here, FIGS. 3A, 3A, 4A, 4A, and 5A, 5A correspond to the AA cross section of FIG. Yes.

In the welding method of the steel pipes 1 and 2, first, as shown in FIG. 1 and FIG. 3A, the lower part of the four side portions 1b of the steel pipe 1 and the steel pipe 2 in a state where the steel pipes 1 and 2 are butted together. These four side portions 2b are temporarily fixed by the four erection pieces 3 (temporary fixing step). Here, the erection piece 3 corresponds to the “temporary fixing means” of the present invention. The erection piece 3 is attached to the outer surface of the lower part of the side part 1b of the steel pipe 1 and the lower part is attached to the outer surface of the upper part of the side part 2b of the steel pipe 2 so as to straddle the welding target area of the steel pipes 1 and 2. .
Then, the position adjustment of the steel pipe 1 with respect to the steel pipe 2 is performed as needed. In addition, about the erection piece 3, it is comprised so that position adjustment of the steel pipe 1 with respect to the steel pipe 2 is possible.

  Next, as shown in FIG. 3 (a), eight ceramic end tabs (flux tabs) 6 are inserted into the gaps between the steel pipes 1 and 2 so as to demarcate the regions where the four corner welds 10 are to be formed. Thus, eight end tabs 6 are installed between the steel pipes 1 and 2. About the end tab 6, it installs between the steel pipes 1 and 2 so that the surface of the side contact | abutted with the corner welding part 10 formed may become a right angle with respect to the circumferential direction of the steel pipes 1 and 2. FIG.

Then, as shown in FIG. 3 (a), the four corner welds 10 are formed by welding the lower ends of the four corners 1a of the steel pipe 1 and the upper ends of the four corners 2a of the steel pipe 2. (Corner weld formation process). In this corner welded portion forming step, the lower end portions of the four corner portions 1a of the steel pipe 1 and the upper end portions of the four corner portions 2a of the steel pipe 2 are welded by semi-automatic welding. Here, the semi-automatic welding means welding in which the supply of the wire is mechanized (refer to the definition of the term “semi-automatic welding” in “JIS Z 3001-1: 2013 Welding Terms—Part 1: General”). . In the present embodiment, carbon dioxide arc welding (CO ₂ welding) is performed as semi-automatic welding. In the corner welding portion forming step, semi-automatic welding is performed by an operator by so-called lateral welding. In the corner welded portion forming step, multi-layer welding is performed in which one corner welded portion 10 is welded in a plurality of passes.

  In the above description, the corner welded portion 10 is formed after the end tab 6 is installed between the steel pipes 1 and 2. However, even if the end tab 6 is installed between the steel pipes 1 and 2 during the formation of the corner welded portion 10. Good. That is, the corner welded portion forming step may include a step of installing the end tab 6 between the steel pipes 1 and 2. In this case, first, positioning welding of about three passes is performed on a portion adjacent to the backing material 4 in the region where the four corner welds 10 are to be formed, and then the four corner welds 10 are formed. Eight end tabs 6 are inserted between the steel pipes 1 and 2 by inserting the eight end tabs 6 into the gaps between the steel pipes 1 and 2 so as to define a predetermined region, and then the four corner welds 10 are formed. Of the planned region, the four corner welded portions 10 may be formed by performing main welding on portions where the positioning welding is not performed. Even in this case, positioning welding and main welding can be performed by semi-automatic welding.

  Next, as shown in FIG. 4A, the eight end tabs 6 are removed. About the edge part 10a with which the end tab 6 was contacting among the square welding parts 10, you may grind | polish the surface by grind | polishing using grinders, such as a grinder, as needed.

  Next, as shown in FIG. 4A, the front erection piece 3 and the rear erection piece 3 are removed from the steel pipes 1 and 2 (temporary fixing means removing step). Even after the front erection piece 3 and the rear erection piece 3 are removed, the steel pipe 1 is connected to the steel pipe through the four corner welds 10, the left erection piece 3, and the right erection piece 3. 2 can be supported in a balanced manner.

  Next, as shown in FIG. 4 (a), the lower end portion of the front side portion 1b and the lower end portion of the rear side portion 1b of the steel pipe 1, and the upper end portion and rear side of the front side portion 2b of the steel pipe 2 are used. The front side welded portion 20 and the rear side welded portion 20 are formed by welding the upper end portion of the side portion 2b (side welded portion forming step). In this side welded portion forming step, the lower end portion of the front side portion 1b and the lower end portion of the rear side portion 1b of the steel pipe 1, the upper end portion of the front side portion 2b of the steel pipe 2, and the upper end of the rear side portion 2b. The parts are welded by automatic welding. Here, automatic welding means welding in which the operation excluding the supply of the base materials (steel pipes 1 and 2) is automated (note: artificial adjustment of welding conditions during welding is possible) ("JIS Z 3001-"). 1: 2013 Welding terminology—see definition of the term “automatic welding” in Part 1: General ”). In the present embodiment, automatic welding is performed using an automatic welding apparatus 40 (see FIG. 7 described later). The configuration of the automatic welding apparatus 40 will be described later with reference to FIG. In the side weld formation process, automatic welding is performed by so-called lateral welding. In the side welded portion forming step, multi-layer welding for welding one side welded portion 20 in a plurality of passes is performed.

  Next, as shown in FIG. 5A, the left erection piece 3 and the right erection piece 3 are removed from the steel pipes 1 and 2 (temporary fixing means removing step). Even after removing the left erection piece 3 and the right erection piece 3, the steel pipe 1 is connected via the four corner welds 10, the front side welds 20, and the rear side welds 20. The steel pipe 2 can be supported in a well-balanced manner.

  Next, as shown in FIG. 5 (a), the lower end of the left side 1b and the lower end of the right side 1b of the steel pipe 1, the upper end of the left side 2b of the steel pipe 2, and the right side The left side welded part 20 and the right side welded part 20 are formed by welding the upper end part of the part 2b (side welded part forming step). In this side welded portion forming step, the lower end portion of the left side portion 1b and the lower end portion of the right side portion 1b of the steel pipe 1, the upper end portion of the left side portion 2b of the steel pipe 2, and the upper end portion of the right side portion 2b, Are welded by automatic welding. Again, automatic welding is performed using an automatic welding apparatus 40 (see FIG. 7 described later). Also in this side welded portion forming step, automatic welding is performed by so-called lateral welding. Moreover, also in this side weld part formation process, the multilayer pile welding which welds in one pass about the one side weld part 20 is performed.

  As described above, the four corner welds 10 and the four side welds 20 are alternately and continuously formed in the circumferential direction of the steel pipes 1 and 2 in the region to be welded of the steel pipes 1 and 2. Is welded around the entire circumference. The corner welded portion 10 is formed between the lower end portion of the corner portion 1 a of the steel pipe 1 and the upper end portion of the corner portion 2 a of the steel pipe 2. The side welding part 20 is formed between the lower end part of the side part 1b of the steel pipe 1 and the upper end part of the side part 2b of the steel pipe 2 facing each other. The side welds 20 are joined to the adjacent corner welds 10 in the formation process.

  FIG. 6 is a diagram showing a welding method for the steel pipes 1 and 2 in a modification of the present embodiment. Here, FIGS. 6A and 6A correspond to the AA cross section of FIG. 1, respectively.

  In this modification, after the four corner welds 10 are formed as shown in FIG. 3 (A), the eight end tabs 6 are removed as shown in FIG. 6 (A). About the edge part 10a with which the end tab 6 was contacting among the square welding parts 10, you may grind | polish the surface by grind | polishing using grinders, such as a grinder, as needed.

  Next, as shown in FIG. 6A, the four erection pieces 3 are removed from the steel pipes 1 and 2 (temporary fixing means removing step). Even after the four erection pieces 3 are removed, the steel pipe 1 can be supported by the steel pipe 2 in a well-balanced manner through the four corner welds 10.

  Next, as shown in FIG. 6A, the four side welds 20 are formed by welding the lower ends of the four sides 1b of the steel pipe 1 and the upper ends of the four sides 2b of the steel pipe 2. It forms (side weld part formation process). In this side welded portion forming step, the lower end portions of the four side portions 1b of the steel pipe 1 and the upper end portions of the four side portions 2b of the steel pipe 2 are welded by automatic welding. Again, automatic welding is performed using an automatic welding apparatus 40 (see FIG. 7 described later). Also in this side welded portion forming step, automatic welding is performed by so-called lateral welding. Moreover, also in this side weld part formation process, the multilayer pile welding which welds in one pass about the one side weld part 20 is performed.

  Also in this modified example, the steel pipes 1 and 2 are formed by alternately and continuously forming the four corner welded portions 10 and the four side welded portions 20 in the circumferential direction of the steel pipes 1 and 2. 1 and 2 are welded over the entire circumference. The corner welded portion 10 is formed between the lower end portion of the corner portion 1 a of the steel pipe 1 and the upper end portion of the corner portion 2 a of the steel pipe 2. The side welding part 20 is formed between the lower end part of the side part 1b of the steel pipe 1 and the upper end part of the side part 2b of the steel pipe 2 facing each other. The side welds 20 are joined to the adjacent corner welds 10 in the formation process.

FIG. 7 is a diagram showing a schematic configuration of the automatic welding apparatus 40 in the present embodiment.
The automatic welding device 40 includes a linearly extending rail 41, an automatic welding robot 42, a welding power source device (not shown), and a welding control device (not shown).

  The rail 41 is provided on the outer surface of the side portion 1b of the steel pipe 1, and extends in parallel with the outer surface and in parallel with the weld line in the side welded portion forming step. Here, the weld line in the side welded portion forming step extends in parallel with the lower end edge of the side portion 1 b of the steel pipe 1 and the upper end edge of the side portion 2 b of the steel pipe 2.

  The automatic welding robot 42 is provided at a traveling device 43 that can reciprocate along the rail 41, a bendable arm 44 that has a proximal end fixed to the traveling device 43 and extends downward, and a distal end portion of the arm 44. And a welding torch 45. The welding torch 45 is a welding torch for gas shielded arc welding, and a welding wire is fed from the tip thereof.

The above-described welding control device controls welding by the automatic welding robot 42.
When the welding speed setting value is input to the welding control device, the traveling of the traveling device 43 is controlled so that the welding speed setting value is obtained. Here, the “welding speed” is a distance at which welding proceeds per unit time, and the unit is, for example, “mm / min”.

  When the set value of the welding current and the set value of the welding voltage are input to the above-described welding control device, the power corresponding to the set value of the welding current and the set value of the welding voltage from the welding power source device to the welding torch 45 Is supplied to the welding wire passing through the welding torch 45.

  In welding by the automatic welding robot 42, the welding amount is determined by the setting value of the welding speed, the setting value of the welding current, and the setting value of the welding voltage input to the above-described welding control device. Here, the “deposition amount” is the amount (mass) of deposited metal per unit weld length, and the unit is, for example, “g / m”.

  Therefore, in this embodiment, the automatic welding robot 42 can reciprocate along the weld line in the side welded portion forming step. In addition, the automatic welding device 40 can automatically perform sideways welding and multi-layer welding in the side welded portion forming step.

  8 and 9 are diagrams illustrating a method of forming the side welded portion 20 in the present embodiment. Here, each of FIGS. 8A to 8C and FIGS. 9A to 9C corresponds to the portion P in FIG. 4A.

  In the present embodiment, the side welded portion 20 has a three-layer structure in which the first layer 21, the intermediate layer 22, and the finishing layer (surface layer) 23 are stacked in this order from the inside to the outside of the steel pipes 1 and 2. (See FIG. 9C).

In the method of forming the side welded portion 20, first, as shown in FIGS. 8A and 8A, the first layer 21 is adjacent to the outer surface of the backing material 4 by automatic welding using an automatic welding device 40. Form.
Next, as shown in FIG. 8C, the intermediate layer 22 is formed so as to be adjacent to the outer surface of the initial layer 21 by automatic welding using the automatic welding device 40.

  Next, as shown in FIG. 9A, a tapered surface 11 is formed on a region of the corner welded portion 10 that covers the end of the bead that constitutes the finishing layer 23 (a region that is planned to cover the end of the bead). Form. The tapered surface 11 is inclined so as to be directed toward the inner side of the steel pipes 1 and 2 as it approaches the side portions 1b and 2b adjacent to the corner welded portion 10 in a plan view (that is, viewed in a horizontal cross section). The tapered surface 11 is formed at the end 10 a of the corner welded portion 10. The tapered surface 11 can be formed at any time after the corner weld 10 is formed and before the finishing layer 23 is formed. For example, a grinding device such as a grinder can be used to form the tapered surface 11.

  Here, “bead” means an elongated band of weld metal made by one pass. “Pass” means one welding operation along the direction of operation during welding (Inada Wada, Ikuo Honjo, Taro Fukunaga, Taiji Arai, Nanao Ishikawa, -Third revision- ", Jikkyo Publishing Co., Ltd., January 25, 1994, p.283).

  Next, as shown in FIG. 9A, the finishing layer 23 is formed so as to be adjacent to the outer surface of the intermediate layer 22 by automatic welding using the automatic welding device 40. In the formation of the finishing layer 23, the end portion of the bead constituting the finishing layer 23 is covered with the tapered surface 11, and the surplus portion 23 a is formed.

Next, as shown in FIG. 9C, the surplus portion 23a is removed by grinding using a grinding device such as a grinder.
In this way, the side welded portion 20 having a three-layer structure is formed.

  FIG. 10 is a diagram showing a back step process 51 and a main welding process 52 at the time of forming the side welded portion 20 in the present embodiment. Here, FIG. 10 corresponds to a portion P in FIG.

  For example, the right corner weld 10 in FIG. 10 corresponds to the “first corner weld” of the present invention, and the left corner weld 10 in FIG. 10 corresponds to the “second corner weld” of the present invention. Can do. That is, FIG. 10 shows a space between the right corner welded portion 10 (first corner welded portion) and the left corner welded portion 10 (second corner welded portion) formed in the aforementioned corner welded portion forming step. Fig. 9 shows a state in which the side weld 20 is formed.

  10 shows one pass 50p (bead 50), back step 51, and main welding step 52 when the intermediate layer 22 constituting the side welded portion 20 is formed, the same as this. The pass (bead), the back step process 51, and the main welding process 52 may be included in the formation of the finishing layer 23 and / or the initial layer 21 described above.

In the aforementioned side welded portion forming process, at least one pass 50p includes a back step process 51 and a main welding process 52. In the present embodiment, the side welded portion forming step described above may include a back step 51 and a main welding step 52 for each pass 50p.
The back step process 51 includes a regression process 51a and a progress process 51b. In FIG. 10, the retreat process 51a and the progress process 51b constituting the back step process 51 are illustrated in an arc shape. However, in practice, the welds of these processes overlap to form a bead. 50.

  In the regression step 51a, welding is advanced from the predetermined position S near the right corner welded portion 10 to the right corner welded portion 10. The predetermined position S is a position away from the right corner welded portion 10 by a predetermined distance D1 on the left corner welded portion 10 side. The predetermined distance D1 is, for example, 5 to 10 mm.

  In the advancing step 51b, welding is advanced toward the left corner welded portion 10 so as to overlap the welded portion welded in the regressing step 51a following the regressing step 51a. Note that the direction in which welding proceeds in the regression step 51a (operation direction) and the direction in which welding proceeds in the progression step 51b (operation direction) are opposite. The pass 50p is folded from the regression step 51a at the right end portion (one end portion) 50a of the bead 50, and proceeds to the progress step 51b.

  In the main welding step 52, the welding is advanced toward the left corner welded portion 10 following the progression step 51b. In addition, the direction (operation direction) in which welding proceeds in the regressing step 51a is opposite to the direction (operation direction) in which welding proceeds in the main welding step 52. Moreover, the direction (operation direction) in which welding proceeds in the progressing step 51b and the direction (operation direction) in which welding proceeds in the main welding step 52 are the same direction.

  In FIG. 10, the back step 51 is adopted at the right end (one end) 50 a of the bead 50, but instead, the back step process 51 is performed at the left end (other end) 50 b of the bead 50. Step process 51 may be adopted.

  In FIG. 10, the welding length in the regression step 51a and the welding length in the progression step 51b are the same (predetermined distance D1). In addition, the welding length in the regression step 51a and the welding length in the progression step 51b. The length may be different.

  In FIG. 10, the back step 51 is performed at the start of one pass 50p (the right end 50a that is the start end side of the bead 50), but in addition to or in place of this, The back step process may be performed at the end of one pass 50p (the left end 50b which is the end side of the bead 50). In this case, the back-step process includes a progress process in which welding is continued to the left corner welded part 10 (second corner welded part) following the main welding process 52 described above, and a weld welded in this progress process. And a regressing step of proceeding welding to a predetermined position near the left corner welded portion 10 (second corner welded portion) so as to overlap the portion. This predetermined position is a position that is a predetermined distance away from the left corner welded portion 10 (second corner welded portion) to the right corner welded portion 10 (first corner welded portion) side. This predetermined distance may be 5-10 mm, for example.

  By the way, in the side welded portion forming step described above, the arc is difficult to stabilize at the start and end of welding, so that a large amount of weld metal is generated, and the weld metal may sag in sideways welding. For this reason, in the above-mentioned side welded part forming process, when the above-mentioned back step process is adopted at the start and / or end of welding, at least the welding amount in the regression process and the welding amount in the progressing process One is preferably less than the amount of welding in the main welding process.

  In order to suppress the sag of the weld metal in this lateral welding, for example, the welding conditions of the main welding process 52 shown in FIG. 11A and the welding conditions of the back step process 51 shown in FIG. It can be set by automatic welding using the automatic welding device 40. Here, the welding conditions shown in FIGS. 11A and 11B are based on the premise that the welding current is 200 A and the welding voltage is 20 V with respect to the crater welding standard setting.

  As shown in FIG. 11A, in the welding conditions of the main welding step 52, when the first layer 21 is formed, the welding current is in the range of 260 to 320A, and the welding voltage is in the range of 30 to 40V. The welding speed is in the range of 250 to 450 mm / min. Further, in the welding conditions of the main welding step 52, when the intermediate layer 22 is formed, the welding current is in the range of 240 to 320A, the welding voltage is in the range of 30 to 40V, and the welding speed is 300 to 550 mm / min. Is within the range. Further, in the welding conditions of the main welding step 52, when the finish layer 23 is formed, the welding current is in the range of 200 to 300A, the welding voltage is in the range of 25 to 35V, and the welding speed is 500 to 800 mm / min. Is within the range.

  As shown in FIG. 11 (a), in the welding conditions of the back step process 51, the welding current is 0.7 to the welding conditions (within a range of 240 to 320A) of the main welding process 52 when the intermediate layer 22 is formed. It is in the range of 1.0 times, the welding voltage is in the range of 0.8 to 1.0 times the welding conditions of the main welding step 52 (in the range of 30 to 40 V), and the welding speed is the main welding. It is in the range of 1.3 to 1.6 times the welding conditions in step 52 (in the range of 300 to 550 mm / min). Moreover, in the welding conditions of the back step process 51, when the finishing layer 23 is formed, the welding current is within a range of 0.4 to 0.7 times the welding conditions of the main welding process 52 (within a range of 200 to 300A). Yes, the welding voltage is in the range of 0.5 to 0.8 times the welding conditions in the main welding process 52 (in the range of 25 to 35 V), and the welding speed is the welding conditions in the main welding process 52 (500 to Within a range of 1.3 to 1.6 times within a range of 800 mm / min.

  In the example shown in FIGS. 11A and 11B, there is no backstep process 51 when forming the first layer 21 and only the main welding process 52. However, when the first layer 21 is formed, the backstep process 51 is performed. Needless to say, there may be step 51.

  The welding current in the back step process 51 (the welding current set in the back step process 51) is preferably equal to or less than the welding current in the main welding process 52 (welding current set in the main welding process 52). In other words, is the welding current in the back step process 51 (the welding current set in the back step process 51) smaller than the welding current in the main welding process 52 (the welding current set in the main welding process 52)? Or it is preferable that it is equivalent to the welding current in the main welding step 52 (the welding current set in the main welding step 52).

  The welding voltage in the back step 51 (the welding voltage set in the back step 51) is preferably equal to or lower than the welding voltage in the main welding step 52 (welding voltage set in the main welding step 52). In other words, is the welding voltage in the back step process 51 (welding voltage set in the back step process 51) lower than the welding voltage in the main welding process 52 (welding voltage set in the main welding process 52)? Or it is preferable that it is equivalent to the welding voltage in the main welding step 52 (the welding voltage set in the main welding step 52).

  The welding speed in the back step process 51 (the welding speed set in the back step process 51) is preferably equal to or higher than the welding speed in the main welding process 52 (welding speed set in the main welding process 52). In other words, is the welding speed in the backstep process 51 (the welding speed set in the backstep process 51) faster than the welding speed in the main welding process 52 (welding speed set in the main welding process 52)? Or it is preferable that it is equivalent to the welding speed in the main welding step 52 (the welding speed set in the main welding step 52).

  In the present embodiment, the welding conditions of the back step process 51 described above can be applied between the predetermined position S and the welding length of 20 to 30 mm.

  By the way, Patent Document 1 discloses that the lower ends of the four corners of the upper steel pipe and the upper ends of the four corners of the lower steel pipe are welded by automatic welding. However, it is difficult to adjust the welding current, welding voltage, welding speed, etc., even if the corners with roundness are actually welded, so the welding quality is not stable. It was difficult to use with. In this respect, in this embodiment, by welding the lower ends of the four corners 1a of the upper steel pipe 1 and the upper ends of the four corners 2a of the lower steel pipe 2 by semi-automatic welding, The welding quality can be stabilized easily. If the welding quality is good even if the lower end of the four corners 1a of the upper steel pipe 1 and the upper end of the four corners 2a of the lower steel pipe 2 are welded by automatic welding, Needless to say, the automatic welding may be used.

  FIG. 6 of Patent Document 1 illustrates that the end portion of the weld bead is formed in a cascade shape. However, in practice, it was difficult to form the end in a clean cascade at the initial stage of welding. In this regard, according to the present embodiment, the tapered surface 11 is formed on the end 10a of the corner weld 10 by grinding the end 10a of the corner weld 10 using a grinding device such as a grinder. Thereby, the taper surface 11 can be formed easily.

  According to this embodiment, the welding method of the steel pipes 1 and 2 is a state in which the steel pipes 1 and 2 having a polygonal cross section having a plurality of corner portions 1a and 2a and a plurality of side portions 1b and 2b face each other up and down. It is a method of welding together. The welding method of the steel pipes 1 and 2 forms the several corner weld part 10 by welding the lower end part of each corner | angular part 1a of the upper steel pipe 1, and the upper end part of each corner | angular part 2a of the lower steel pipe 2. FIG. After the corner welded portion forming step (see FIG. 3 (a)) and the corner welded portion forming step, the lower end portion of each side portion 1b of the upper steel pipe 1 and the upper end portion of each side portion 2b of the lower steel pipe 2 A side welded portion forming step (see FIGS. 4 (a), 5 (a), and 6 (a)) for forming a plurality of side welded portions 20 by welding. In the side welded part forming step, the lower end of each side 1b of the upper steel pipe 1 and the upper end of each side 2b of the lower steel pipe 2 are welded by automatic welding. Therefore, for example, after forming the plurality of corner welds 10, the temporary fixing means such as the erection piece 3 can be removed, and after removing the temporary fixing means, the plurality of side welds 20 can be formed. Further, even after the temporary fixing means such as the erection piece 3 is removed, the lower steel pipe 2 can support the upper steel pipe 1 through the four corner welds 10 in a well-balanced manner.

  Further, according to the present embodiment, in the corner welded portion forming step (see FIG. 3A), the lower end portion of each corner portion 1a of the upper steel pipe 1 and the upper end portion of each corner portion 2a of the lower steel pipe 2 Are welded by semi-automatic welding. Therefore, the worker who welds the corners 1a and 2a of the steel pipes 1 and 2 welds the corners 1a and 2a of the steel pipes 1 and 2 by semi-automatic welding, and then moves to the next construction place for welding. Work can be done and there is no need to return to the original construction site. Therefore, the welding operation can be performed efficiently.

  Further, according to the present embodiment, in the side welded portion forming step (see FIGS. 4 (a), 5 (a), and 6 (a)), the corner welded portion forming step (see FIG. 3 (a)). A side weld 20 is formed between the right corner weld 10 (first corner weld) and the left corner weld 10 (second corner weld) formed as described above (see FIG. 10). In the side welded portion forming process, at least one pass 50p includes a back step process 51 and a main welding process 52. The back step 51 includes a regressing step 51a that advances welding from a predetermined position S in the vicinity of the right corner weld 10 (first corner weld) to the right corner weld 10 (first corner weld). Then, following the regression step 51a, a progression step 51b of proceeding welding toward the left corner welded portion 10 (second corner welded portion) so as to overlap the welded portion welded in the regression step 51a. Including. In the main welding step 52, the welding is advanced toward the left corner welded portion 10 (second corner welded portion) following the proceeding step 51b. As a result, an arc is generated in front of the weld end (for example, the right end 50a of the bead 50) at the joining surface position (for example, the position where the right end 50a of the bead 50 and the right corner weld 10 are joined). Penetration by a stable arc can be achieved.

  Further, according to the present embodiment, in the side welded portion forming step (see FIGS. 4 (a), 5 (a), and 6 (a)), the corner welded portion forming step (see FIG. 3 (a)). A side weld 20 is formed between the right corner weld 10 (first corner weld) and the left corner weld 10 (second corner weld) formed as described above (see FIG. 10). In the side welded portion forming process, at least one pass 50p includes a back step process 51 and a main welding process 52. The back step 51 includes a right corner weld from a predetermined position S that is a predetermined distance D1 away from the right corner weld 10 (first corner weld) to the left corner weld 10 (second corner weld). Regression step 51a in which welding is performed up to part 10 (first corner welded portion), and left corner welded portion 10 (overlapping the welded portion welded in regression step 51a, following regression step 51a. Progressing step 51b which advances welding toward the second corner welded portion). In the main welding step 52, the welding is advanced toward the left corner welded portion 10 (second corner welded portion) following the proceeding step 51b. As a result, an arc is generated in front of the weld end (for example, the right end 50a of the bead 50) at the joining surface position (for example, the position where the right end 50a of the bead 50 and the right corner weld 10 are joined). Penetration by a stable arc can be achieved.

  Further, according to the present embodiment, the amount of welding in the regression step 51 a is made smaller than the amount of welding in the main welding step 52. Thereby, dripping of the deposited metal at the starting end of the horizontal welding can be suppressed. In addition, it is possible to make the weld height uniform.

  Further, according to the present embodiment, the amount of welding in the proceeding step 51 b is made smaller than the amount of welding in the main welding step 52. Thereby, dripping of the deposited metal at the starting end of the horizontal welding can be suppressed. In addition, it is possible to make the weld height uniform.

  Moreover, according to this embodiment, the edge part of the bead welded in the edge welding part formation process (refer FIG. 4 (a), FIG. 5 (a), and FIG. 6 (a)) among the corner welding parts 10. FIG. The tapered surface 11 is formed in the region covered by the cover prior to the end of the bead covering the region. The tapered surface 11 is inclined so as to be directed toward the inner side of the steel pipes 1 and 2 as the side parts 1b and 2b adjacent to the corner welded part 10 are approached. Therefore, the end portion of the bead can be smoothly put on the end portion 10a of the corner weld portion 10.

  Moreover, according to this embodiment, the welding method of the steel pipes 1 and 2 is the lower part of the side part 1b of the upper steel pipe 1, and the lower steel pipe 2 prior to the corner welded part forming step (see FIG. 3 (A)). A temporary fixing step (see FIGS. 1 and 3A) for temporarily fixing the upper portion of the side portion 2b to the upper portion of the side portion 2b by the temporary fixing means (erection piece 3) and a corner welded portion forming step (see FIG. 3A). Before and prior to the side welded portion forming step (see FIGS. 4 (a), 5 (a), and 6 (a)), the temporary fixing means (erection piece 3) is attached to the upper steel pipe 1 and A temporary fixing means removing step (see FIGS. 4A, 5A, and 6A) for removing from the lower steel pipe 2 is further included. Therefore, as in this embodiment, after the four corner welds 10 are formed, the four temporary fixing means (erection piece 3) are removed, and after the temporary fixing means are removed, the four side welded parts 20 are Can be formed. Further, even after the four temporary fixing means (erection piece 3) are removed, the lower steel pipe 2 can support the upper steel pipe 1 through the four corner welds 10 in a well-balanced manner.

  Moreover, according to this embodiment, the cross-sectional shape of the steel pipes 1 and 2 is a polygon, and the cross-sectional shape of the steel pipes 1 and 2 is a rectangle in the example shown to FIG. In the corner welded portion forming step (see FIG. 3A), the lower end portions of the four corner portions 1a of the upper steel pipe 1 and the upper end portions of the four corner portions 2a of the lower steel pipe 2 are welded. By doing so, four corner welds 10 are formed. Therefore, after the four corner welds 10 are formed, the four temporary fixing means (erection piece 3) can be removed, and the four side welded parts 20 can be formed after the temporary fixing means are removed. Further, even after the four temporary fixing means (erection piece 3) are removed, the lower steel pipe 2 can support the upper steel pipe 1 through the four corner welds 10 in a well-balanced manner.

According to the present embodiment, the corner portions 1a and 2a are rounded. Thus, even if the corner portions 1a and 2a are rounded, the steel pipes 1 and 2 can be efficiently welded to each other.
Moreover, according to this embodiment, the construction method of the pillar 100 includes the above-described welding method of the steel pipes 1 and 2. Therefore, the work which welds steel pipes 1 and 2 at the time of construction of pillar 100 can be performed efficiently.

  The illustrated embodiments are merely examples of the present invention, and the present invention is not limited to those directly described by the described embodiments, and various improvements and modifications made by those skilled in the art within the scope of the claims. Needless to say, it encompasses changes.

1, 2 Steel pipe 1a, 2a Corner 1b, 2b Side 3 Erection piece (temporary fixing means)
4 Backing material 5 Tapered surface 6 End tab 10 Square welded portion 10a End portion 11 Tapered surface 20 Side welded portion 21 Initial layer 22 Intermediate layer 23 Finishing layer (surface layer)
23a Extra section 40 Automatic welding device 41 Rail 42 Automatic welding robot 43 Traveling device 44 Arm 45 Welding torch 50 Bead 50a Right end (one end)
50b Left end (other end)
50p Pass 51 Back step 51a Regression 51b Progress 52 Main welding 100 Column

Claims (8)

It is a method of welding each other in a state in which steel pipes having a polygonal cross section having a plurality of corners and a plurality of sides are butted against each other,
A corner welded part forming step of forming a plurality of corner welds by welding the lower end of each corner of the upper steel pipe and the upper end of each corner of the lower steel pipe;
Side welded portion forming step of forming a plurality of side welded portions by welding the lower end portion of each side portion of the upper steel pipe and the upper end portion of each side portion of the lower steel pipe after the corner welded portion forming step. When,
Including
A steel pipe welding method in which, in the side welded portion forming step, a lower end portion of each side portion of the upper steel pipe and an upper end portion of each side portion of the lower steel pipe are welded by automatic welding.   The steel pipe welding method according to claim 1, wherein, in the corner welded portion forming step, a lower end portion of each corner portion of the upper steel pipe and an upper end portion of each corner portion of the lower steel pipe are welded by semi-automatic welding. In the side welded portion forming step, the side welded portion is formed between the first corner welded portion and the second corner welded portion formed in the corner welded portion forming step,
In the side welded portion forming process, at least one pass has a back step process and a main welding process,
The back step process includes
A regressing step of proceeding welding from a predetermined position near the first corner weld to the first corner weld;
Following the regressing step, an advancing step of proceeding welding toward the second corner welded portion so as to overlap the welded portion welded in the regressing step;
Including
3. The steel pipe welding method according to claim 1, wherein, in the main welding step, welding is advanced toward the second corner welded portion subsequent to the progressing step.   The welding method of the steel pipe of Claim 3 which makes the welding amount in the said regression process smaller than the welding amount in the said main welding process.   A taper surface is formed in a region where the end of the bead to be welded in the side welded portion forming step is covered before the end of the bead is covered in the region. The steel pipe welding method according to any one of claims 1 to 4. The polygon is a rectangle;
In the corner welded portion forming step, four corner welds are formed by welding the lower end portions of the four corner portions of the upper steel pipe and the upper end portions of the four corner portions of the lower steel pipe. The steel pipe welding method according to any one of claims 1 to 5.   The steel pipe welding method according to any one of claims 1 to 6, wherein the corner portion is rounded.   A column construction method including the steel pipe welding method according to any one of claims 1 to 7.