JP5376662B2 - Steel tube column base joining method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a steel pipe column base joint method which can achieve stable full penetration welding when obtaining a rib-less welding joint between a steel pipe column and a base plate whose plate thicknesses are largely different from each other. <P>SOLUTION: A groove is formed in the outer surface of the lower end of the steel pipe column 11. A hole 12a having a diameter equal to the inner diameter of the steel pipe column 11 is formed in the base plate 12. The steel pipe column 11 is vertically abutted against the base plate 12 so that the inside surface of the steel pipe column 11 coincides with that of the base plate hole 12a when viewed from the pipe axis direction, and a cylindrical backing material 13 having an outer diameter fittable to the inside surface of the steel pipe column 11, having a circumferential groove 13a formed in the outer surface thereof, and detachable after welding is abutted on the inside surface of the steel pipe column 11 and on the inside surface of the hole 12a so that the circumferential groove 13a strides a boundary between the inside surface of the steel pipe column 11 and the inside surface of the base plate hole 12a. The steel pipe column 11 and the base plate 12 are welded to each other from the outer surface side of the lower end of the steel pipe column 11 so that a penetration bead projects into the circumferential groove 13a, and then the backing material is removed. Full penetration welding can be stably achieved, and can be confirmed by visual observation. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a steel pipe column base joining method in which a lower end portion of a steel pipe column is welded and fixed to a base plate when a steel pipe column having a large plate thickness difference and a base plate are joined without a rib.

Steel pipes are generally used for the main pillars of outdoor lights, signs, signals, etc. When installing this steel pipe pillar, the base plate is welded and fixed to the lower end of the steel pipe pillar, and this base plate is anchor bolt. In general, the base plate exposed type structure is fixed to the foundation.
In this case, the column base joint portion is generally a column base joint structure in which a steel pipe column is fillet welded to a base plate and stiffened by a rib or the like. The ribs are generally triangular and are vertically fixed on the base plate and applied to the outer peripheral surface of the steel pipe column and fixed by welding.

In the column base joint structure with ribs, there is a problem such as hindrance because the rib protrudes, and from the recent demand for universal design, the exposed column base joint structure without ribs seems to be adopted It has become.
In this type of structure, as shown in FIG. 12, the steel pipe column 1 is inserted into the hole 2a formed in the base plate 2, and the upper and lower two-stage corners are formed by two locations, the lower end of the steel pipe column 1 and the upper edge of the hole 2a of the base plate 2. A method of joining by meat welding is common. The fillet weld is indicated by 3. This welding method does not result in full penetration welding.

  It can be said that the column base joining method in Patent Document 1 is substantially the same as that shown in FIG. However, Patent Document 1 is different in that it is fillet welding only on the outer periphery of the pipe (“the welding is performed without uneven distribution along the outer periphery of the pipe main body” (described in paragraph [0011])). The invention of Patent Document 1 is characterized in that the thickness of the main body portion of the base plate 2 is larger than the thickness of the spot facing portion, not the welded portion.

There is also a welding method with a groove without a backing material, in which a groove is formed on the outer peripheral surface side of the lower end of the steel pipe column and is mounted on the base plate by welding.
However, for example, in the case of a lighting column, since the difference in thickness between the steel tube column and the base plate is generally large, welding is performed by increasing the heat input with a relatively large current and voltage. For this reason, we aimed for complete penetration welding. In this case, it is necessary to install a steel backing material directly at the joint.
That is, as shown in FIG. 13, a groove is formed on the outer peripheral surface of the lower end of the steel pipe column 5, and welding is performed in a state where the backing metal 7 is attached to the lower end of the steel pipe column 5 or the base plate 6 (Patent Document 2). ). A weld is indicated by 8.

JP 2003-343119 A JP 2000-008494 A

  In the column base joining method by fillet welding as shown in FIG. 12 or Patent Document 1, there is a problem in management of welding quality in that an internal defect due to nondestructive inspection cannot be performed. In addition, in order to ensure the welding strength, it is necessary to perform two-stage welding (two rounds for one round each at two locations), and there is a problem that the work efficiency is poor and the cost is high.

With the above-described welding method with a groove without a backing material, it is possible to inspect internal defects due to nondestructiveness. However, when the thickness difference between the steel pipe column and the base plate is large, it is difficult to obtain a good weld.
On the other hand, in the column base joining method using the backing material as shown in FIG. 13, even if the plate thickness difference between the steel pipe column and the base plate is large, complete penetration welding is possible, but the welding conditions for obtaining a good weld are obtained. There is a problem that is severe. In addition, it is not always necessary to perform complete penetration welding, and it is desired that complete penetration welding that does not require strict defect inspection can be obtained stably.
In addition, if there is a backing material, the back wave of the weld cannot be visually confirmed, so there is a problem that quality control cannot be performed only by visual observation.

  The present invention was made to eliminate the above-mentioned conventional drawbacks, and when obtaining a welded joint without a rib between a steel pipe column and a base plate having a large plate thickness difference, complete penetration welding can be stably realized, And it aims at providing the steel pipe pillar base joining method which can confirm it visually and has favorable working efficiency.

The invention of claim 1 which solves the above-mentioned problem is a steel pipe column base joining method in which a lower end portion of a steel pipe column is welded and fixed to a base plate when obtaining a welded joint without a rib between a steel pipe column having a large plate thickness difference and a base plate. There,
A groove is formed in the outer surface of the lower end of the steel pipe column, a hole is formed in the base plate with the same diameter as the inner diameter of the steel pipe column, and the steel pipe column is formed in the base plate so that its inner surface coincides with the inner surface of the base plate hole when viewed from the tube axis direction. A cylindrical backing material that has a diameter that can be fitted to the inner surface of the steel pipe column and has a circumferential groove formed on the outer surface and that can be removed after welding is formed.The circumferential groove is formed between the inner surface of the steel tube column and the inner surface of the base plate hole. The steel pipe column and the base plate are applied to the inner surface of the steel pipe column and the hole so as to straddle the boundary, and the steel pipe column and the base plate are welded from the outer surface of the lower end of the steel pipe so that the back bead protrudes into the circumferential groove of the backing material, and then backed. It is characterized by removing the material.

  A second aspect of the present invention is the steel pipe column base joining method according to the first aspect, wherein the backing material is made of a copper plate or ceramic.

  Claim 3 is the steel pipe column base joining method according to claim 1 or 2, wherein the steel tube column is temporarily attached to the base plate, and the backing material is inserted into the peripheral groove using a backing material fixing jig disposed in the hole of the base plate. Is applied to the inner surface of the steel tube column and the inner surface of the hole so as to straddle the boundary between the inner surface of the steel tube column and the inner surface of the base plate hole, and the base plate support rotation drive unit in the welding machine having a base plate support rotation drive unit that supports and rotates the base plate Fix the base plate, direct the welding torch at the groove on the outer surface of the lower end of the steel pipe, and rotate the base plate integrally with the steel pipe column so that the steel pipe column and the base plate protrude into the circumferential groove of the backing material. It is characterized by welding and then removing the backing material.

According to the present invention, since a groove is provided on the outer surface of the lower end of the steel pipe column and welded to the base plate using the backing metal, the backing metal is disposed so as to straddle the boundary between the steel pipe column inner surface and the base plate hole inner surface. And welded so that the back bead protrudes into the circumferential groove. After welding, check the back bead visually to confirm that complete penetration welding has been performed. be able to. In addition, according to the test result of the applicant of the present application, if the back bead is confirmed, it can be generally determined that complete penetration welding has been performed.
Moreover, it is easy to obtain a uniform backside bead, and it becomes easy to obtain a certain welding quality.
Also, in welding with a large plate thickness difference between a thin steel pipe column and a thick base plate, it is difficult to set appropriate welding conditions to obtain a good weld. By setting the welding conditions in which welding joining is performed so as to project inward, it is possible to set conditions for performing complete penetration welding, and it is possible to stably realize complete penetration welding.
In addition, unlike the conventional method of performing fillet welding of upper and lower two stages, only one stage is required, so that the work efficiency of the welding work is good.
Further, since the backing material is removable, it can be reused and is economical.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure explaining the state at the time of welding and fixing a steel pipe column to a baseplate by the steel pipe column base joining method of one Example of this invention, (a) is a top view which showed the steel pipe column in the cross section (B- of (b)) (Equivalent to B sectional drawing), (b) is AA sectional drawing of (a). It is a partially cutaway principal part enlarged view of FIG. FIG. 3 is an enlarged view of a main part of FIG. 2. (A) is the figure which expanded and showed only the backing material in FIG. 1 (a), (b) is the principal part enlarged view of (a). It is a figure explaining the condition which fixes a steel pipe pillar and a baseplate to the baseplate support rotation drive part of a welding machine in the state of FIG. 1, and welds. It is sectional drawing which showed the state by which the steel pipe column and the baseplate were welded. It is a macro sectional photograph taken by cutting the welded part between the steel pipe column and the base plate. (A) shows the case where the raised back bead is clearly obtained, (b) shows the raised back bead. It is a thing when it was not done. It is the enlarged view which showed only the backing material and backing material fixing jig in FIG. It is the figure which showed only the backing material fixing jig in FIG. (A) is the figure which showed the four segment members in FIG. 9, (b) shows one segment member, and is C arrow line view of (a). It is the figure which showed the segment support member in FIG. 9, (a) is a top view, (b) is D arrow directional view of (a). It is a partially cutaway front view of a state in which a conventional steel pipe column base joining method is shown, and a steel pipe column is welded to a base plate and installed on a foundation. It shows the other conventional steel pipe column base joining method, and is a cross-sectional view near the lower end of a steel pipe column welded and fixed to a base plate.

  Hereinafter, the Example of the steel pipe pillar base joining method of this invention is described with reference to FIGS.

FIG. 1 is a view for explaining a state when a steel pipe column is welded and fixed to a base plate by a steel pipe column base joining method according to an embodiment of the present invention, and (A) is a plan view showing a cross section of the steel pipe column ((B)). (B) is a cross-sectional view taken along the line AA in FIG. FIG. 2 is an enlarged view of a principal part of FIG. 1 (b), and FIG. 3 is an enlarged view of the principal part of FIG.
In these drawings, 11 is a steel pipe column, 12 is a base plate, 13 is a backing material, and 14 is a backing material fixing jig.
The steel pipe column 11 used in the welding test described later has a plate thickness of 4.2 mm and the base plate 12 has a thickness T of 19 to 40 mm. However, the present invention provides a rib between the steel pipe column and the base plate having a large difference in plate thickness. This is a steel pipe column base joining method in which the lower end portion of the steel pipe column 11 is welded and fixed to the base plate 12 when obtaining the welded portion without, and the steel pipe column 11 is welded and fixed to the base plate 12 as follows.
For example, a 45 ° groove 11 a is formed on the outer surface of the lower end of the steel pipe column 11, and a hole 12 a having the same diameter as the inner diameter of the steel pipe column 11 is formed in the base plate 12.
The lower end of the steel pipe column 11 is applied to the base plate 12 so that its inner surface coincides with the inner surface of the base plate hole 12a when viewed from the tube axis direction. In the embodiment, there is no route gap.

The backing material 13 has a cylindrical shape having an outer diameter that can be fitted to the inner surface of the steel pipe column 11 and has a circumferential groove 13a formed on the outer surface, and is removable after welding. The backing material 13 is preferably made of a material having a high melting point and high thermal conductivity. In the embodiment, it is made of a copper plate. Ceramics can also be used. That the backing material is “removable after welding” means that the material does not melt at the time of welding and does not solidify integrally with the weld metal part, or satisfies the condition.
As shown in FIG. 4, the backing material 13 of the example was formed by curving a strip-shaped copper plate with both ends sharpened in opposite taper shapes to form a ring shape, and wrapping the tapered both end portions 13 b. Is. The wrapped both ends 13b can slide with each other, and the diameter of the ring-shaped backing material 13 can be elastically increased. In the state where the diameter is not expanded, the entire tapered surfaces S of both end portions 13b are in contact with each other as shown in an enlarged view in FIG. 4B, and the thickness of the lap portion at this time is equal to the thickness of the copper plate. . When the diameter is expanded and the both end portions 13b are slid away from each other, the thickness of the lap portion is slightly reduced, but there is no particular problem because the thickness is slight.

  As shown in FIG. 3 in an enlarged manner, the backing material 13 is formed so that the circumferential groove 13a straddles the boundary P between the inner surface of the steel pipe column 11 and the inner surface of the base plate hole 12a. It fixes to the inner surface of the hole 12a. The detailed structure of the backing material fixing jig 14 for fixing the backing material 13 and the specific procedure for fixing the backing material 13 using this will be described later.

In the state where the steel pipe column 11 and the base plate 12 are positioned as described above and the backing material 13 is set on the inner surface, a welding torch 32 is attached to the groove on the lower outer surface of the steel pipe column 11 as shown in FIG. Then, the base plate 12 is rotated integrally with the steel pipe column 11, and the steel pipe column 11 and the base plate 12 are welded together over the entire circumference. In this case, the welding conditions are set so that the back bead protrudes into the circumferential groove 13a of the backing material 13, and then the welding is performed.
After the welding is completed, the backing material 13 is removed.
Thereby, as schematically shown in FIG. 6, it is possible to obtain a welded portion (a weld metal portion is indicated by 15) having a cross-section in which the back bead 15 a clearly appears (FIG. 6 will be described later). This corresponds roughly to the macro sectional photograph of FIG.

The test performed in order to select the weld condition in which a favorable weld is obtained when the steel pipe column 11 is welded to the base plate 12 as described above will be described.
The specimens are as shown in Table 1, the size of the steel pipe column 11 is φ177.8 × 4.2 mm, the base plate 12 is 350 × 350 × T (plate thickness T = 19, 25, 36, 40) mm, the base plate The hole diameter is 169.4 (+0, −1.5 mm). The number of specimens is 4 types of No. 1 to No. 4, 16 pieces of 4 pieces each. The welding materials are as shown in Table 1.
The backing material 13 has a copper plate ring shape shown in FIG. 4, and in FIG. 3, the width W = 30 mm, the plate thickness 5 mm, the width w of the circumferential groove 13a = 15 mm, and the depth 1 mm. In addition, although it seems that the width of the circumferential groove of the backing material is 10 to 20 mm, it does not necessarily have to be the size.
Then, four types of 16 specimens were welded by changing various combinations of welding conditions of “current A, voltage V, frequency Hz, speed mm / sec”.
The combination of welding conditions "current A, voltage V, frequency Hz, speed mm / sec"
"260A-35V-32Hz-650mm / sec"
"270A-30V-20Hz-400mm / sec"
"270A-35V-32Hz-650mm / sec"
「280A-34V-35Hz-700mm / sec」
「280A-36V-32Hz-650mm / sec」
「280A-34V-35Hz-800mm / sec」
"290A-34V-40Hz-800mm / sec"
"290A-36V-40Hz-800mm / sec"
"290A-38V-40Hz-800mm / sec"
I went there.
After welding was completed, external defect inspection and internal defect inspection (ultrasonic flaw detection test, macro structure test) were performed to check the status of the weld. In the external defect inspection, the appearance of welds such as undercuts, overlaps, pits, surface cracks, weld toe shapes, etc. were inspected, and the situation of the back bead in particular was confirmed.
In the ultrasonic flaw detection test, it was performed on the entire circumference of the welded portion, and the presence / absence of a defect, the size and position of the defect (position in the 360 ° circumferential direction) were examined. In addition, after the ultrasonic flaw detection test, macro cross-sectional photographs were taken at 2 to 5 locations in the circumferential direction of the weld bead for each specimen. The location where the cross section was examined was taken up appropriately where the back bead clearly appeared and where it did not.

7A and 7B show a part of a macro cross-sectional photograph of a weld bead in the above welding test.
FIG. 7A shows the portion where the raised back bead is clearly obtained (position in the circumferential direction), and FIG. 7B shows the case where the raised back bead is not obtained.
In the place where the raised back bead was clearly obtained in the appearance inspection, no flaw was detected in the place by the ultrasonic flaw detection test, and as a result of examining the cross section, it completely melted as shown in the macro cross-sectional photograph of FIG. 7A. Welding was performed (there was almost no unwelded portion between the steel pipe column and the base plate).
On the other hand, at the location where the back bead did not come out (the position in the circumferential direction), there were cases where a flaw was detected at the location in the ultrasonic flaw detection test and when it was not. And as a result of examining the cross section for the portion where the back bead did not come out, there was a case where there was an unwelded portion due to insufficient penetration as in the macro sectional photograph of FIG. 7B, and there was a complete penetration welding without an unwelded portion. There was a case.
In addition, there existed another factors, such as the case where a pipe pipe core shift | offset | difference occurred as well as the case where it was thought that the welding conditions were not appropriate as a cause which the back wave bead did not come out (circumferential position).
From the above, if the raised back bead can be clearly confirmed over the entire circumference, it can be judged that complete penetration welding has been performed for the entire circumference.
Depending on the results of a large number of welding tests, it may be considered that the inspection standard is “welding quality is acceptable when back waves can be confirmed”. In that case, it becomes possible to omit internal defect inspections such as an ultrasonic flaw detection test.
In the welding experiment using the 16 specimens, the number of specimens was not sufficient, so a clear and regular relationship between complete penetration welding and welding conditions could not be obtained. For example, with a base plate thickness of 19 mm Under the welding conditions of "280A-36V-32Hz-650mm / sec", almost complete penetration welding was performed. When the base plate 12 had a thickness of 25 mm and 36 mm, almost complete penetration welding was performed under the welding conditions of “280 A-34 V-35 Hz-700 mm / sec”. With the base plate 12 having a thickness of 40 mm, almost complete penetration welding was performed under the welding conditions of “280A-34V-35Hz-800 mm / sec” and “290A-38V-40Hz-800 mm / sec”.

A detailed structure of the backing material fixing jig 14 of the embodiment used for fixing the backing material 13 will be described with reference to FIGS. 5 and 8 to 11.
8 is an enlarged view showing only the backing material 13 and the backing material fixing jig 14 in FIG. 1A, and FIG. 9 is a diagram showing only the backing material fixing jig 14 in FIG.
The backing material fixing jig 14 includes four segment members 21 and a segment support member 22 that supports the four segment members 21.
As shown in FIG. 10, each segment member 21 has a fan-shaped plate portion 23, an arc-shaped side wall portion 24 rising from the outer circular arc portion, and a bolt insertion hole 25a, and is fixed to the fan-shaped plate portion 23 vertically. The support plate portion 25 is formed.
As shown in FIG. 11, the segment support member 22 includes a plate-shaped ring 27, a nut 28 welded and fixed to a hole 27 a formed in two perpendicular directions of the plate-shaped ring 27, and a screw on the nut 28. It consists of a backing material expansion bolt 29 combined.

A specific procedure for welding and joining the base portion of the steel pipe column 11 to the base plate 12 using the backing material fixing jig 14 will be described.
First, a position where the backing material 13 is to be fixed is marked in the hole 12a of the base plate 12.
The backing material 13 is arranged in the base plate hole 12a in accordance with the marking, and fixed to the inner surface of the base plate hole 12a by the backing material fixing jig 14 arranged inside the backing material 13. At that time, the backing material diameter increasing bolt 29 of the segment support member 22 of the backing material fixing jig 14 is turned to push the arc-shaped side wall portions 24 of the four segment members 21 outward in the radial direction. The backing material 13 is expanded in diameter via the arc-shaped side wall portion 24, and pressed and fixed to the inner surface of the hole 12 a of the base plate 12.
Next, the base plate 12 is fixed to the base plate support rotation drive unit 31 in the automatic welding machine having the base plate support rotation drive unit 31 schematically shown in FIG. Reference numeral 31a denotes a disk-like support part that supports the base plate 12, and 31b denotes a drive part that rotationally drives the support part 31a.
Next, the steel pipe column 11 is abutted against the base plate 12 so that the lower end portion of the steel pipe column 11 is covered with the outer periphery of the backing material 13 fixed in the hole 12a of the base plate 12 by the backing material fixing jig 14, and the steel pipe column 11 is After confirming that it is exactly horizontal, it is temporarily attached to the base plate 12 at, for example, three locations in the circumferential direction. In the embodiment, since there is no root gap, it is easy to set the steel pipe column 11 to the base plate 12.
In this state, as shown in FIG. 2, FIG. 3, FIG. 5, etc., the backing material 13 has its circumferential groove 13a straddling the boundary P between the inner surface of the steel pipe column 11 and the inner surface of the base plate hole 12a, It contacts the inner surface of the steel pipe column 11 and the inner surface of the hole 12a.

In the state where the steel pipe column 11 and the base plate 12 are positioned as described above and the backing material 13 is set on the inner surface, a welding torch 32 is attached to the groove on the lower outer surface of the steel pipe column 11 as shown in FIG. The steel pipe column 11 and the base plate 12 are welded over the entire circumference while rotating the base plate 12 integrally with the steel pipe column 11 (torch angle is 40 ° or 45 °, etc.). In this case, the welding conditions are set so that the back bead protrudes into the circumferential groove 13a of the backing material 13, and then the welding is performed.
After the welding is completed, the base plate 12 is removed from the support portion 31a of the base plate support rotation drive unit 31, and then the bolt 29 of the backing material fixing jig 14 is loosened to remove the backing material 13 together with the backing material fixing jig 14. .
Next, it is confirmed that the backside bead has protruded from the inner surface in an appropriate state. Thereby, the weld joint part by which complete penetration welding was performed can be obtained.
In addition, after confirming a back bead and confirming that there is no welding defect, you may scrape a back bead and may be flush with the inner surface of a steel pipe column.

According to the steel pipe column base joining method, the backing material 13 having the circumferential groove 13a is set so that the circumferential groove 13a straddles the boundary P between the inner surface of the steel tube column 11 and the inner surface of the hole 12a of the base plate 12. Therefore, as described above, after welding and welding, the back bead can be visually confirmed to confirm that complete penetration welding has been performed.
In welding with a large plate thickness difference between the thin steel pipe column 11 and the thick base plate 12, it is difficult to set appropriate welding conditions for obtaining a good weld, but the back bead is backed. By setting the welding conditions under which welding joining is performed so as to project into the circumferential groove 13a of the material 13, it is possible to set the conditions under which complete penetration welding is performed, and to achieve complete penetration welding stably. It becomes possible.
Moreover, it is easy to obtain a uniform backside bead, and it becomes easy to obtain a certain welding quality.
In addition, unlike the conventional method of performing fillet welding of upper and lower two stages, only one stage is required, so that the work efficiency of the welding work is good.
Moreover, since the backing material 13 is removable, it can be reused and is economical.
Further, since the inner surface of the steel pipe column 11 and the inner surface of the hole 12a of the base plate 12 are flush with each other, more electric wires and the like can be passed through the steel tube column as compared with the conventional steel tube column base joining method shown in FIG. .

In the embodiment, a copper plate is used as a backing material, but ceramic can be used. In the case of a ceramic product, it is preferable to use a segmented one divided into a plurality of segments in order to follow the inner surface of the steel pipe column.
The size (width W, plate thickness) of the backing material 13 is not limited to the size used in the test example, but may be appropriately changed according to the size of the steel pipe column and the base plate, or according to other conditions.
The width w of the circumferential groove 13a of the backing material 13 is suitably 10 to 20 mm in the case of the size of the steel pipe column and base plate of the test example. Further, the depth h of the circumferential groove 13a may be appropriately in a range of 0.5 to 5 mm depending on the size of the steel pipe column and the base plate.

In the embodiment, the backing material fixing jig 14 is fixed to the base plate 12 side together with the backing material 13 by pressing the backing material 13 against the inner surface of the base plate hole 12 a with the backing material fixing jig 14. On the contrary, the backing material fixing jig can be fixed to the steel tube column 11 side together with the backing material 13 by pressing the backing material 13 against the inner surface of the steel tube column 11 with the backing material fixing jig. is there. It is also possible to set the backing material 13 with a backing material fixing jig fixed on the welding machine side.
Moreover, the structure of the backing material fixing jig is not limited to that of the embodiment, and various structures can be used.

In the embodiment, the base plate 12 is rotationally driven and welded, but the steel pipe column 11 side can be rotationally driven and welded.
In the embodiment, MAG welding is adopted as the welding method, but other arc welding methods may be adopted. Moreover, although the semi-automatic or automatic welding machine is suitable for the welding machine to be used, it is not necessarily limited to this.
In the present invention, the present invention is applied to a welding joint in which the thickness difference between a thin steel pipe column and a thick base plate is large. For example, the steel pipe column thickness is 4.2 to 12 mm and the base plate thickness is 16 mm. The plate thickness ratio is preferably about 52 mm or so, and the thickness of the base plate is preferably 3 to 12 times the plate thickness of the steel pipe column.
Specific examples of the steel pipe column are mainly main lamps such as an illuminating lamp, a sign, and a signal. However, the present invention can be applied to various steel pipe column base joint structures having no exposed base plate and having no ribs.

11 Steel pipe column 12 Base plate 12a Hole (base plate hole)
13 Backing material 13a Circumferential groove 13b Both ends 14 Backing material fixing jig 15 Welded part (welded metal part)
15a Back wave bead 21 Segment member 22 Segment support member 23 Fan-shaped plate portion 24 Arc-shaped side wall portion 25 Support plate portion 25a Bolt insertion hole 27 Plate-shaped ring 27a Hole 28 Nut 29 Backing material expanded bolt 31 Base plate (for welding machine) Support rotation drive part 31a Support part 31b Rotation drive part 32 Welding torch

Claims (3)

When obtaining a welded joint without ribs between a steel pipe column and a base plate with a large plate thickness difference, a steel pipe column base joining method in which the lower end of the steel pipe column is welded and fixed to the base plate,
A groove is formed in the outer surface of the lower end of the steel pipe column, a hole is formed in the base plate with the same diameter as the inner diameter of the steel pipe column, and the steel pipe column is formed in the base plate so that its inner surface coincides with the inner surface of the base plate hole when viewed from the tube axis direction. A cylindrical backing material that has a diameter that can be fitted to the inner surface of the steel pipe column and has a circumferential groove formed on the outer surface and that can be removed after welding is formed.The circumferential groove is formed between the inner surface of the steel tube column and the inner surface of the base plate hole. The steel pipe column and the base plate are applied to the inner surface of the steel pipe column and the hole so as to straddle the boundary, and the steel pipe column and the base plate are welded from the outer surface of the lower end of the steel pipe so that the back bead protrudes into the circumferential groove of the backing material, and then backed. Steel pipe column base joining method characterized by removing material.   The steel pipe column base joining method according to claim 1, wherein the backing material is made of a copper plate or ceramic.   Temporarily attach a steel pipe column to the base plate, and use the backing material fixing jig placed in the hole of the base plate to attach the backing material so that the circumferential groove spans the boundary between the inner surface of the steel pipe column and the inner surface of the base plate hole. The base plate is fixed to the base plate support rotation drive unit in a welding machine having a base plate support rotation drive unit that supports the base plate and rotates by supporting the base plate and the inner surface of the hole, and the welding torch is directed to the groove on the outer surface of the lower end of the steel pipe. The steel pipe column and the base plate are welded and joined so that a back bead protrudes into the circumferential groove of the backing material, and then the backing material is removed. Or the steel pipe pillar base joining method of 2.