JP2014161852A - Backing strip for welding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a backing strip for welding capable of following up a recess-projection of a work, and capable of surely preventing melting omission by the welding.SOLUTION: The backing strip 30 for the welding is formed in a belt shape, and in the backing strip 30, an overlapping part 30c overlapping with an end part of a groove 10b of a square steel pipe (the work) 10 and a gap formation part 30b for securing a root gap by projecting from the end part of the groove 10b of the square steel pipe 10, are mutually provided in parallel over the other end part from one end part in the longitudinal direction. In the overlapping part 30c, a notch line 30a bendable along a shape of an inside surface 12a abutting on the overlapping part 30c in the square steel pipe 10, is provided in one or a plurality of places.

Description

  The present invention relates to a welding backing metal used when welding and joining column bases and columns of steel structure columns.

  Steel pipes are often used as the pillar body of steel structure pillars. When a steel pipe is used for the column main body, the steel pipe functions as a column material by welding and joining a diaphragm or a column base to the steel pipe. In this type of welding joint, butt welding is generally used, and a backing metal is used for butt welding. For example, when a square steel pipe (square tube) is employed as the column main body, the column main body has four corners on the inner surface. For this reason, the thing of the shape along the curvature of the corner | angular part of a square steel pipe is used as backing metal.

  By the way, the inner surface of the square steel pipe and the backing metal need to be in close contact as much as possible in order to perform good welding. If the gap between them is large, the welding material may leak out from the gap and cause a welding defect. In addition, depending on the manufacturing method, the square steel pipe may not only bend the corners but also have irregularities or inclinations in the flat plate portion between the corners, or there may be a deviation between the inner core and the outer core. Moreover, these states are slightly different for each square steel pipe. On the other hand, since the backing metal is uniformly produced by a press machine or the like, there is a problem that it is difficult to cope with variations in the inner side surface shape of each square steel pipe.

  For such a problem, for example, Patent Document 1 discloses a backing metal body that is bent so as to be in contact with the inner peripheral surface of a corner portion of a column portion. On the inner side surface of the bent portion of the backing metal main body, a square groove group having a plurality of square grooves whose groove width from the opening to the bottom surface is substantially constant is formed. Further, the square grooves are formed by cutting so as to be orthogonal to the longitudinal direction of the backing metal main body, and the square grooves are substantially equally spaced in the longitudinal direction.

Utility Model Registration No. 3163334

  However, in the configuration of Patent Document 1, since the square groove is formed also in the protruding portion that protrudes from the column portion and should secure the root gap, the bottom portion of the groove that becomes thin by forming the square groove is reduced. It can be considered that it melts during welding.

  Then, an object of this invention is to provide the backing metal for welding which can follow the unevenness | corrugation of a workpiece | work and can prevent the through-hole by welding reliably.

  The welding backing metal of the present invention is formed in a band shape, and an overlapping portion that overlaps the contact surface of the end portion of the workpiece and a gap forming portion that protrudes from the end portion of the workpiece and secures a root gap are longitudinal directions. Are provided in parallel from one end to the other end. The overlapping portion is provided with one or a plurality of bending induction portions that allow bending along the shape of the contact surface of the workpiece.

  In this welding backing metal, since the bending induction part is provided in the overlapping part of the backing metal, the backing metal is applied from the gap forming part to the overlapping part in accordance with the shape of the contact surface of the workpiece. It can be bent easily. Moreover, since the bending induction part is provided in the overlap part and the bending formation part is not provided in the gap formation part, the predetermined thickness as a welding backing metal is maintained in the gap formation part. Thereby, even when welding the end part of the workpiece, it is possible to prevent the gap forming part from being melted. As described above, according to the present invention, it is possible to follow the unevenness of the workpiece and to reliably prevent the melt-through by welding.

  One end of the bending induction part is preferably located at the boundary between the overlapping part and the gap forming part. In this case, one end portion of the bending induction portion can be used as a positioning mark when the welding backing metal is placed on the workpiece. Specifically, the welding backing metal is installed so that one end of the bending inducing portion is just hidden behind the end of the workpiece. Thereby, the protrusion length of the gap formation part from the edge part of a workpiece | work is always maintained constant, and only a gap formation part can be made to protrude from the edge part of a workpiece | work. Further, the welding backing metal can be installed on the workpiece without using a separate ruler or the like, so that the workability can be improved.

  The bend-inducing portion has one end located at the boundary between the overlapped portion and the gap forming portion, and the other end located in the middle of the overlapped portion, or a cut line, or the other end It is preferable that it is a notch extended to the other edge part of an overlap part. Thus, by providing a hole or cut line or notch, there is no hole or cut line or notch around the hole or cut line or the portion where the notch is provided. The strength is lower than that of the part. As a result, the welding backing metal can be easily bent starting from the hole, the cut line, or the notch. Further, since the hole, the score line, or the notch is formed so as to penetrate the welding backing metal, these can be easily formed.

  The bending inducing portion is preferably a groove that is recessed from the back surface on the opposite side to the surface in contact with the workpiece toward the surface. In this case, the strength of the portion where the groove is provided by the recessed groove and the periphery thereof are lower than the portion where no groove is present. As a result, the backing metal can be easily bent using the recessed groove as a bent portion. Further, since this groove does not penetrate the welding backing metal, it is possible to reliably prevent the welding material from leaking inside the welding backing metal.

  The gap forming part preferably has a protruding length from the overlapping part equal to the root gap. In this case, with the welding backing metal attached to the end of the work so that the gap forming part protrudes, another work is brought into contact with the tip of the gap forming part so that the gap is formed between these works. A route gap having an accurate length can be provided, and workability can be improved.

  The thickness of the gap forming part is preferably larger than the distance between the root gaps. In this case, the thickness of the gap forming portion can be sufficiently ensured, and the gap forming portion can be reliably prevented from being melted during welding.

  ADVANTAGE OF THE INVENTION According to this invention, the unevenness | corrugation of a workpiece | work can be tracked and the through-hole by welding can be prevented reliably.

It is a side view of the pillar concerning an embodiment. It is a side view which shows the junction part of the square steel pipe and column base of FIG. It is the figure which looked at the square steel pipe of FIG. 2 from the edge part by the side to which the backing metal was attached. It is a figure which shows the backing metal of FIG. 3, (a) is a front view, (b) is a top view. It is the perspective view which looked at the square steel pipe shown in FIG. 2 from the edge part by the side to which the backing metal was attached. It is a front view of the backing metal which concerns on a modification. It is a figure which shows the backing metal which concerns on a modification, (a) is a front view, (b) is sectional drawing along the VII (b) -VII (b) line | wire in (a). It is a front view of the backing metal which concerns on a modification. It is a figure which shows the state which attached the backing metal which concerns on another modification to the square steel pipe. It is a figure which shows the state which attached the backing metal which concerns on another modification to the square steel pipe.

  Hereinafter, a preferred embodiment of a column to which a welding backing metal according to the present invention is applied will be described with reference to the drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.

  As shown in FIG. 1, the column 1 includes a square steel pipe (work) 10 and a column base 20. The pillar 1 is used as a pillar of a steel structure building. The square steel pipe 10 is formed in a square tubular shape, and the column base 20 is a metal plate material formed in a flat plate shape. The square steel pipe 10 and the column base 20 are joined by butt welding. The square steel pipe 10 is erected on the base portion 2 so that the column base 20 contacts the base portion 2. When the column base 20 is brought into contact with the upper surface of the base portion 2, the bolt 3 protruding from the upper surface of the base portion 2 is passed through a bolt hole provided in the column base 20. By attaching the nut 4 to the bolt 3 and connecting the column base 20 and the foundation 2, the standing state of the column 1 is maintained.

  Here, the detail of the square steel pipe 10 is demonstrated using FIG.2 and FIG.3. As shown in FIGS. 2 and 3, the square steel pipe 10 uses a so-called extra-thick steel pipe having a very large thickness (for example, a thickness of about 20 mm to 25 mm). Further, the square steel pipe 10 is a seamless square steel pipe having a small radius of curvature R (for example, about R = 0 mm to 3 mm). As shown in FIG. 3 in particular, the square steel pipe 10 has four corner portions 11 and four flat plate portions 12 that connect between the adjacent corner portions 11.

  The four flat plate portions 12 have substantially the same length when viewed along the extending direction of the square steel pipe 10. The four corner portions 11 have substantially the same bent shape.

  Such a square steel pipe 10 is obtained by, for example, heating a columnar steel material, forming holes along the axis of the columnar steel material, and forming with a roller so that the cross-sectional shape is a square frame shape. be able to. Thereby, the square steel pipe 10 becomes a seamless steel pipe. In addition, when a square steel pipe is manufactured by such a manufacturing method, the inner shape of the manufactured square steel pipe is slightly different between individual square steel pipes, for example, the center of the inner surface (inner core) and the center of the outer surface (outer core). May be slightly different, or the curvature of the corners on the inner surface may be slightly different at each corner.

  Moreover, when the square steel pipe 10 is manufactured as described above, the inner side surface (contact surface) 12a of the flat plate portion 12 includes one end portion to which one corner portion 11 is connected and the other corner portion 11. The central portion 12b between the other end portions to be connected is bent in a valley shape as a bent portion. More specifically, the inner surface 12a is inclined toward the outside of the square steel pipe 10 as it goes from the end on the side to which the corner 11 is connected to the center 12b. In the present embodiment, the case where the inner side surface 12a of the flat plate portion 12 is bent in a valley shape with the central portion 12b as a bent portion will be described as an example, but the present invention is applied even when the inner surface 12a is bent in a mountain shape. can do.

  Thereby, the four inner side surfaces 12a formed inside the square steel pipe 10 have an octagonal shape in which the positions of the four corner portions 11 and the positions of the four central portions 12b are bent portions. The angle of inclination of each octagonal corner of the inner surface 12a may differ depending on each side and each square steel pipe 10. In addition, as the square steel pipe 10, steel materials, such as SS400 or SM490A, STKR490, can be used, for example.

  As shown in FIG. 2, in order to weld and join the column base 20 and the square steel pipe 10 to an end portion (hereinafter referred to as “contact side end portion”) 10 a connected to the column base 20 in the square steel pipe 10. A groove 10b used in the above is formed. The tip of the groove 10b and the column base 20 are arranged with a predetermined interval (for example, an interval of about 5 mm to 7 mm), and the interval is set as a route gap for butt welding. In addition, in FIG. 2, the state before welding is shown.

  A backing metal 30 that secures a root gap between the end of the groove 10b and the column base 20 is provided at the abutting side end 10a of the square steel pipe 10 on the inner side surface 12a. Four backing metals 30 are used, and the four backing metals 30 abut against the inner side surfaces 12a of the four flat plate portions 12, respectively. As the backing metal 30, for example, a steel material such as SS400 or SS490A, which is the same material as the square steel pipe 10, can be used. When joining the square steel pipe 10 and the column base 20, the square steel pipe 10 and the column base 20 are butt-welded using the backing metal 30 as a backing.

  Next, the details of the backing metal 30 will be described. As shown in FIG. 4, the backing metal 30 is a plate material formed in a strip shape. The backing metal 30 includes a gap forming part 30b and an overlapping part 30c. The overlapping portion 30 c overlaps the inner side surface 12 a when the backing metal 30 is overlapped on the inner side surface 12 a of the flat plate portion 12. The gap formation part 30b protrudes from the edge part of the groove | channel 10b of the square steel pipe 10, when it overlaps with the inner surface 12a. The protruding length of the square steel pipe 10 from the groove 10b in the gap forming portion 30b is equal to the root gap for butt welding. Due to the protrusion of the gap forming portion 30b, a route gap between the end portion of the groove 10b of the rectangular steel pipe 10 and the column base 20 can be secured. Of the backing metal 30, at least the thickness of the gap forming portion 30b is larger than the distance between the root gaps. For example, the thickness of the backing metal 30 including the gap forming portion 30b can be set to 6 mm to 9 mm. The four backing golds 30 have the same shape.

  The gap forming portion 30b and the overlapping portion 30c are provided in parallel to each other from one end portion to the other end portion in the longitudinal direction of the belt-like backing metal 30. Specifically, in FIG. 4A, the gap forming part 30b is above the two-dot chain line, and the overlapping part 30c is below the two-dot chain line. The overlapping portion 30c has a larger width when viewed in the longitudinal direction than the gap forming portion 30b, and is, for example, 4 to 8 times the width of the gap forming portion 30b. The overlapping portion 30c is provided with a cut line (bending inducing portion) 30a that enables bending along the shape of the inner surface 12a of the flat plate portion 12. As shown in FIG. 4A, in this embodiment, the remaining portion below the cut line 30a in the overlapping portion 30c is the height of the gap forming portion 30b (when the gap forming portion 30b is viewed in the longitudinal direction). The length of the cut line 30a is at least half the height of the gap forming portion 30b. Alternatively, the cut line 30a may be provided so that the total length of the remaining portion below the cut line 30a in the overlapping part 30c and the height of the gap forming part 30b is shorter than the length of the cut line 30a. Good. The cut line 30a is a hole whose one end is located at the boundary between the overlapping portion 30c and the gap forming portion 30b and whose other end is located in the middle of the overlapping portion 30c. That is, the cut line 30 a extends in a direction orthogonal to the longitudinal direction of the backing metal 30. Further, the cut line 30 a is provided at a position shifted to one end side of both end portions in the longitudinal direction of the backing metal 30. The groove width of the cut line 30a can be set to 0.2 mm, for example. The backing metal 30 can be formed by, for example, laser processing.

  As shown in FIGS. 3 and 5, the length of the backing metal 30 in the longitudinal direction is substantially the same as the length from one corner 11 connected to both ends of the flat plate portion 12 to the other corner 11. Have The backing metal 30 is arranged such that both end portions in the longitudinal direction face the one corner portion 11 and the other corner portion 11 in a state of being overlapped with the inner side surface 12 a of the flat plate portion 12. Further, the central portion between both end portions in the longitudinal direction of the backing metal 30 abuts on the inner side surface 12 a of the flat plate portion 12.

  When the backing metal 30 is brought into contact with the inner surface 12a, the cut line 30a provided in the backing metal 30 is opposed to the central portion 12b of the inner surface 12a. Since the cut line 30a is provided at a position shifted to one end side in the longitudinal direction of the backing metal 30, the end of one backing metal 30 among the backing metals 30 adjacent to each other. Enters the deeper position of the bent portion in the corner portion 11 (the center position of the bent portion) than the end portion of the other backing metal 30, and the end portion of the other backing metal 30 extends to the one backing metal 30. It is opposed to the end of this with a predetermined interval. That is, when the backing metal 30 is provided, the adjacent backing metals 30 win or lose each other. In addition, the edge part of the other backing metal 30 and the edge part of one backing metal 30 may contact | abut.

  As a result, the backing metal 30 is shifted to the end side to which one corner 11 is connected, out of the two corners 11 connected to both ends of the flat plate portion 12 with which the backing metal 30 abuts. In contact with the inner side surface 12a. Further, when viewed along the circumferential direction of the inner side surface 12a of the square steel pipe 10, the four backing metals 30 are arranged so that the opposing states of the end portions of the backing metal 30 in the respective corner portions 11 are the same. Deploy. Thereby, adjacent backing metal 30 adjoins most at the corner | angular part 11. FIG.

  Next, a procedure for joining the square steel pipe 10 and the column base 20 will be described. First, a groove 10b is provided on the abutting side end 10a side of the square steel pipe 10. And the four backing metal 30 is each installed in the four inner surface 12a of the edge part by the side of the groove | channel 10b in the square steel pipe 10. FIG. At this time, the backing metal 30 is installed so that only the gap forming part 30b of the backing metal 30 protrudes from the end of the groove 10b. At this time, by installing the backing metal 30 so that the end of the cut line 30a on the gap forming portion 30b side is just hidden behind the end of the groove 10b of the square steel pipe 10, the cutting line 30a is attached to the backing metal 30. It can be used as a positioning mark for installation, and only the gap forming portion 30b can be protruded from the end portion.

  Further, when the backing metal 30 is viewed along the circumferential direction of the inner side surface 12a of the square steel pipe 10, the backings are arranged so that the opposing states (winning and losing) of the ends of the adjacent backing metal 30 are the same. Gold 30 is installed. Next, the cut line 30a is opposed to the central part 12b so as to follow the shape of the inner side surface 12a bent with the central part 12b as a bent part, and the cut line 30a is pushed into the central part 12b to center the cut line 30a. The backing metal 30 is bent into a square shape. When the backing metal 30 is bent, a vise, a hand vice, or the like can be used.

  Next, the backing metal 30 and the groove 10b of the square steel pipe 10 are assembled and welded (temporary welding). In particular, the back portion of the backing metal 30 can be prevented from being bent back by assembling and welding the vicinity of the backing metal 30 where the cut line 30a is formed and the groove 10b. Next, the column base 20 is brought into contact with the tip of the gap forming portion 30b of the backing metal 30, and the square steel pipe 10 and the column base 20 are welded and joined using the backing metal 30 as a backing. When the square steel pipe 10 and the column base 20 are welded to each other, a root gap between the square steel pipe 10 and the column base 20 is filled with a welding material by performing multiple layers of welding.

  The present embodiment is configured as described above, and the overlap portion 30c of the backing metal 30 is provided with the cut line 30a, so that the overlap portion is formed from the gap forming portion 30b in accordance with the shape of the inner surface 12a of the square steel pipe 10. The backing metal 30 can be easily bent over 30c. Moreover, since the cut line 30a is provided in the overlapping part 30c and the cut line 30a is not provided in the gap forming part 30b, a predetermined thickness as the backing metal 30 is maintained in the gap forming part 30b. . Thereby, even when welding the groove 10b of the rectangular steel pipe 10, it is possible to prevent the gap forming portion 30b from being melted. Thus, according to the backing metal 30 according to the present embodiment, it is possible to follow the unevenness of the inner side surface 12a of the square steel pipe 10 and to reliably prevent through-melting due to welding.

  By positioning one end portion of the cut line 30a at the boundary between the gap forming portion 30b and the overlapping portion 30c, the one end portion of the cut line 30a is connected to the backing metal 30 on the inner surface 12a of the square steel pipe 10. It can be used as a positioning mark when installing. Thereby, the protrusion length of the gap formation part 30b from the groove | channel 10b of the square steel pipe 10 is always maintained constant, and only the gap formation part 30b can be protruded from the groove | channel 10b front-end | tip part of the square steel pipe 10. Moreover, the backing metal 30 can be installed in the square steel pipe 10 without using a separate ruler or the like, and the workability can be improved.

  The cut line 30a formed in the overlapping portion 30c is a hole whose one end is located at the boundary between the overlapping portion 30c and the gap forming portion 30b and whose other end is located in the middle of the overlapping portion 30c. Thus, by providing the cut line 30a in the overlapping portion 30c, the strength of the portion where the cut line 30a is provided and the periphery thereof is lower than that of the portion where the cut line 30a does not exist. As a result, the backing metal 30 can be easily bent starting from the score line 30a. Further, since the cut line 30a is formed so as to penetrate the backing metal 30, the cut line 30a can be easily formed.

  The protruding length from the overlapped portion 30c in the gap forming portion 30b is the same as the root gap when the square steel pipe 10 and the column base 20 are butt welded. In this case, the column base 20 is attached to the gap forming portion with the backing metal 30 attached to the tip of the groove 10b of the rectangular steel tube 10 so that the gap forming portion 30b protrudes from the tip of the groove 10b of the rectangular steel tube 10. By abutting on the tip of 30b, a route gap with an exact length can be provided between the square steel pipe 10 and the column base 20, and workability can be improved.

  In the backing metal 30, at least the thickness of the gap forming portion 30 b is made larger than the distance between the root gaps. In this case, the thickness of the gap forming portion 30b can be sufficiently ensured, and the gap forming portion 30b can be reliably prevented from being melted when the rectangular steel pipe 10 and the column base 20 are welded to each other. .

  In the corner portion 11 of the square steel pipe 10, one end portion of one backing metal 30 of the pair of backing metals 30 abutted at the corner portion 11 is deeper than the bent portion of the corner portion 11. The other end of the other backing metal 30 is opposed to one end of the one backing metal 30 with a predetermined gap. In this way, the backing metal 30 is not bent in accordance with the curved state of the corner portion 11 of the square steel pipe 10, and two members of the backing metal 30 are prepared with the corner portion 11 of the square steel pipe 10 as a boundary. Matches with the edge winning or losing. Thereby, in the corner | angular part 11, the clearance gap between the backing metal 30 and the square steel pipe 10 can be made remarkably small. Furthermore, it is not necessary to prepare a backing metal 30 that matches the bent state of the corner portion 11 of the square steel pipe 10, so that the workability can be improved and the gap can be reduced. Thus, according to the present invention, the interval between the corner of the square steel pipe 10 and the backing metal 30 can be reduced while simplifying the shape of the backing metal. As described above, according to the present embodiment, the interval between the corner portion of the square steel pipe 10 and the backing metal 30 can be reduced while simplifying the shape of the backing metal 30. Moreover, when the curvature radius R of the corner | angular part 11 is small like the square steel pipe 10 used by this embodiment, the flat plate part 12 becomes long. For this reason, by arranging the backing metal 30 appropriately along the flat plate portion 12 without a gap as in the present embodiment, a sufficient welding length can be secured in the flat plate portion 12, and excessively in the corner portion. Therefore, it is possible to suppress the need for welding accuracy and to improve workability.

  The four backing metal 30 have the same length, and the opposing state of the ends of the backing metal 30 in each corner 11 is when the inner surface 12a of the square steel pipe 10 is viewed along the circumferential direction. Same for each. In this case, since the backing metal 30 is stored in the same corner 11, the backing metal 30 can be shared, and the number of member types can be reduced.

  Even if the inner side surface 12a of the flat plate portion 12 with which the backing metal 30 abuts is bent, the backing metal 30 is bent according to the bending of the inner side surface 12a of the flat plate portion by providing a cut line 30a. The degree of contact between the inner surface 12a and the backing metal 30 can be increased. Moreover, since the score line 30a is provided at a position shifted from the longitudinal center of the backing metal 30, it is possible to suppress mistaking of the orientation when the backing metal 30 is installed on the flat plate portion 12.

  Further, the gap between the square steel pipe 10 and the backing metal 30 in the flat plate portion 12 of the square steel pipe 10 is made smaller than the gap between the square steel pipe 10 and the backing metal 30 around the corner 11 of the square steel pipe 10. The function of the backing metal 30 as a backing is improved, and the reliability of the welded joint between the square steel pipe 10 and the column base 20 can be improved. However, the gap in the corner portion 11 of the square steel pipe 10 is filled in the first layer welding when the square steel pipe 10 and the column base 20 are joined by welding.

  In the corner portion 11 of the square steel pipe 10, the adjacent backing metal 30 are opposed to each other by winning and losing, so that the gap generated in the corner portion 11 can be made as small as possible, and the reliability of welding is improved.

  Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment. For example, although the cut line 30a is provided on the backing metal 30, the cut line 30a may be extended to the end of the overlapping portion 30c. Specifically, as shown in FIG. 6, one end of the overlapping portion 30c of the backing metal 30A is positioned at the boundary between the gap forming portion 30b and the overlapping portion 30c, and the other end is the overlapping portion 30c. You may provide the notch (bending induction part) 31 extended to the other edge part. In this case, the backing metal 30A can be bent more easily along the shape of the inner surface 12a of the corner portion 11.

  Furthermore, it may be a configuration in which a groove is provided instead of the cut line 30a. Specifically, as shown in FIG. 7A and FIG. 7B, in the overlapping portion 30c of the backing metal 30B, from the back surface on the opposite side to the surface contacting the inner surface 12a, the surface is directed from the back surface. The groove (bending induction part) 32 may be recessed. In this case, due to the recessed groove 32, the strength of the portion where the groove 32 is provided and the periphery thereof is lower than the portion where the groove 32 does not exist. Accordingly, the backing metal 30B can be easily bent using the recessed groove 32 as a bent portion, similarly to the case where the cut line 30a is provided. Further, since the groove 32 does not penetrate the backing metal 30B like the cut line 30a, the welding material leaks inward from the backing metal 30 when the square steel pipe 10 and the column base 20 are welded to each other. Can be surely prevented.

  Further, instead of the cut line 30a, a plurality of small-diameter holes (bending induction portions) 33 may be provided in the overlapping portion 30c as in a backing metal 30C shown in FIG. Even in this case, it is possible to obtain the same effect as the case where the cut line 30a is provided.

  Moreover, in the said embodiment and modification, although the notch line 30a, the notch 31, the groove | channel 32, and the small diameter hole 33 were each provided in backing metal 30,30A, 30B and 30C, the notch line 30a, You may provide the notch 31, the groove | channel 32, and the small diameter hole 33 in the several places of the overlap part 30c. In this case, for example, even if the inner side surface 12a of the flat plate portion 12 in the square steel pipe 10 is bent at a plurality of locations, the backing metal 30 and the like can be easily bent in accordance with the shape of the inner side surface 12a.

  Further, as shown in FIG. 9, two U-shaped backing metal 30 </ b> D may be arranged inside the square steel pipe 10 instead of the backing metal 30. Similarly to the backing metal 30, the backing metal 30 </ b> D is also provided with a gap forming portion that protrudes from the tip of the groove 10 b of the square steel pipe 10 and an overlapping portion that overlaps the inner side surface 12 a. The backing metal 30D includes a band-shaped main body 30d and two small pieces 30e that are bent and extended from both ends of the main body 30d. When the backing metal 30D is disposed in the square steel pipe 10, the connecting portion between the small piece portion 30e and the main body portion 30d faces the corner portion 11. When the small piece portion 30e and the main body portion 30d are formed, the strip-shaped plate material can be formed by providing one or a plurality of grooves and bending the plate material starting from the grooves. Alternatively, the small piece portion 30e and the main body portion 30d can be formed by bending a band-shaped plate material without forming a groove, or by forming such a U-shaped mold material. The small piece portion 30e and the main body portion 30d are formed so as to abut on the adjacent inner side surface 12a with the corner portion 11 interposed therebetween.

  The main body 30d is provided with a score line 30a at a position facing the central portion 12b (bent portion) of the inner surface 12a. By providing the cut line 30a in the main body portion 30d, the main body portion 30d of the backing metal 30D can be easily formed along the inner side surface 12a bent with the flat plate portion 12d as a bent portion, similarly to the backing metal 30 in the above-described embodiment. It becomes possible to bend it. Thus, even when the U-shaped gap forming portion 30 b is used, the backing metal 30 </ b> D can be reliably brought into contact with the inner side surface 12 a of the square steel pipe 10.

  Further, as shown in FIG. 10, instead of the backing metal 30, a substantially C-shaped backing metal 30 </ b> E formed in an octagonal shape avoiding the corners may be arranged inside the square steel pipe 10. Similarly to the backing metal 30, the backing metal 30 </ b> E is also provided with a gap forming portion that protrudes from the tip of the groove 10 b of the square steel pipe 10 and an overlapping portion that overlaps the inner side surface 12 a. The backing metal 30E includes contact portions 30f, 30g, 30h, 30i and 30j and connecting portions 30k, 30m, 30n and 30p.

  The abutting portions 30f and 30g abut on the first inner side surface 12a among the four inner side surfaces 12a formed on the inner side of the square steel pipe 10. The abutting portion 30 h abuts on the second inner side surface 12 a among the four inner side surfaces 12 a formed on the inner side of the square steel pipe 10. The abutting portion 30 i abuts on the third inner side surface 12 a among the four inner side surfaces 12 a formed on the inner side of the square steel pipe 10. The abutting portion 30j abuts on the fourth inner side surface 12a among the four inner side surfaces 12a formed on the inner side of the square steel pipe 10. The connecting part 30k connects the contact part 30f and the contact part 30h. The connecting part 30m connects the contact part 30h and the contact part 30i. The connecting part 30n connects the contact part 30i and the contact part 30j. The connecting part 30p connects the contact part 30j and the contact part 30g. When the backing metal 30E is used, the weld length is sufficiently secured only in the region excluding the connecting portions 30k, 30m, 30n, and 30p.

  The backing metal 30E is formed by bending a belt-shaped plate material. Note that one or a plurality of grooves may be provided in the bent portion of the plate material, and the plate material may be bent starting from the groove. The connecting portions 30k, 30m, 30n, and 30p are separated from the square steel pipe 10 corner portion 11 by a predetermined distance. The contact part 30f and the contact part 30g are opposed to each other with the central part 12b of the flat plate part 12 interposed therebetween. That is, the contact portions 30f and 30g do not straddle the bent portion of the first inner surface 12a. Thereby, the contact parts 30f and 30g can be reliably contacted with the first inner surface 12a.

  Similar to the backing metal 30 according to the above-described embodiment, the contact portions 30h, 30i, and 30j are provided with cut lines 30a. Thereby, the contact parts 30h, 30i, and 30j of the backing metal 30E can be easily bent according to the shape of the second to fourth inner side surfaces 12a.

  In the above-described embodiments and modifications, the square steel pipe 10 to which the backing metal 30 and the like are attached is a so-called extra-thick steel pipe having a very large thickness. A thin steel pipe may be used. In addition to a seamless steel pipe, a cold-formed square steel pipe formed in an annular shape by bending a flat plate and welding the ends to each other may be used. When a cold-formed square steel pipe is used, a convex weld is formed on the inner surface of the flat plate portion of the steel pipe. When attaching the backing metal 30 to such a cold-formed square steel pipe, the notch 30a of the backing metal 30 is opposed to the convex welded portion, and the backing metal 30 is attached along the shape of the inner surface of the steel pipe. Bend. Thus, by bending the backing metal 30 with the cut line 30a of the backing metal 30 facing the welded portion, even in a cold-formed square steel pipe having a convex welded portion on the inner surface, the inner surface of the steel pipe The backing metal 30 can be attached along the shape.

  In particular, the substantially C-shaped backing metal 30E formed in an octagon described with reference to FIG. 10 may be attached to a cold-formed square steel pipe having a convex weld on the inner surface.

  In the embodiment and the modification described above, the case where the backing metal 30 or the like is used when joining the square steel pipe 10 and the column base 20 is described. The present invention can also be applied to a case where a column and a beam joint (diaphragm) are joined, or the above-described two members are joined.

  DESCRIPTION OF SYMBOLS 1 ... Column, 10 ... Square steel pipe (workpiece), 11b ... Groove, 11 ... Square part, 12 ... Flat plate part, 12a ... Inner side surface, 12b ... Central part, 20 ... Column base, 30, 30A, 30B, 30C, 30D, 30E, 30F ... backing metal (backing metal for welding), 30a ... cut line (bending induction part), 30b ... gap forming part, 30c ... overlapping part, 31 ... notch (bending induction part), 32 ... Groove (bend inducing part), 33... Small diameter hole (bending inducing part).

Claims (6)

An overlapping portion that is formed in a belt shape and overlaps the contact surface of the end portion of the workpiece, and a gap forming portion that protrudes from the end portion of the workpiece and secures a root gap from one end portion in the longitudinal direction to the other end portion. Are provided in parallel with each other,
The overlapping portion is provided with one or a plurality of bending induction portions that allow bending along the shape of the contact surface of the workpiece.
Backing metal for welding.   2. The welding backing metal according to claim 1, wherein one end portion of the bending induction portion is located at a boundary between the overlapping portion and the gap forming portion. The bending inducing portion has one end located at the boundary between the overlapping portion and the gap forming portion, and the other end located in the middle portion of the overlapping portion, or a cut line, or the other Is a notch that extends to the other edge of the overlapped portion,
The welding backing metal according to claim 2.   3. The welding backing metal according to claim 1, wherein the bending inducing portion is a groove that is recessed toward the surface from a back surface that is opposite to a surface that contacts the workpiece.   The said gap formation part is a backing metal for welding as described in any one of Claims 1-4 whose protrusion length from the said overlap part is equal to the said root gap.   The welding backing metal according to claim 5, wherein a thickness of the gap forming portion is larger than an interval between the route gaps.

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