Weld assembly box type cross section member and manufacturing method of the same

Abstract

To provide a weld assembly box type cross section member which does not require a large manufacturing facility, can suppress a heat input amount during welding, and can be manufactured with a small number of man-hours.SOLUTION: In a weld assembly box type cross section member 1 where corner weld is performed in a state where four skin plates are assembled so as to become a rectangular cross section, a first skin plate 11 and a second skin plate 12 are arranged on a pair of surfaces opposing to each other, and a third skin plate 13 and a fourth skin plate 14 are sandwiched by the first skin plate and the second skin plate on the other pair of surfaces opposing to each other, and grooves are provided on both ends in the width direction of the first skin plate, but grooves are not provided on the second skin plate. Out of both ends in a width direction of the third skin plate and the fourth skin plate, a groove is not provided on one end corner-welded with the first skin plate, and a groove is provided on an outside surface side of the weld assembly box type cross section member on the other end corner-welded with the second skin plate, and corner weld is performed at the groove.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a welded assembled box-shaped cross-section member configured by joining four skin plates so as to have a rectangular cross-section, and a method for manufacturing the same.

Background Art

[0002] Square steel pipes such as cold-rolled formed square steel pipes, cold-pressed formed square steel pipes, and welded assembled box-shaped cross-section members are often used for column members of buildings. Among these, relatively inexpensive cold-rolled formed square steel pipes and cold-pressed formed square steel pipes are often used for column members of mid-rise and high-rise buildings. On the other hand, in the lower part of super high-rise buildings, since the rigidity and strength required for column members are extremely large, welded assembled box-shaped cross-section members that enable large cross-sections, thickening, and high strength are often used.

[0003] Here, the welded assembled box-shaped cross-section member has a higher manufacturing cost than cold-rolled formed square steel pipes and cold-pressed formed square steel pipes. As a factor, it is mentioned that a large number of man-hours are required for welding construction management and the like during the manufacture of the welded assembled box-shaped cross-section member. This will be explained below.

[0004] As shown in FIGS. 4(a) and 4(b), the welded assembled box-shaped cross-section members 8 and 9 are manufactured by performing fillet welding W in a state where four skin plates 81 to 84 and 91 to 94 are combined so as to have a rectangular cross-section. Here, as a welding method for the fillet welding W of the welded assembled box-shaped cross-section members 8 and 9 having a large wall thickness, it is common to apply submerged arc welding. Specifically, as shown in FIGS. 4(a) and 4(b), the skin plates on both sides or one side of the fillet welding W are cut obliquely to form V-groove 81g to 84g or J-groove 93g and 94g. Then, by performing submerged arc welding on this groove, the four skin plates 81 to 84 and 91 to 94 are joined to each other. Since the heat input amount by submerged arc welding is large, backing bars 85 and 95 are provided on the back side of the fillet welding W.

[0005] The submerged arc welding of these welded and assembled box-shaped cross-sectional members 8 and 9 is performed in a downward position as shown in FIGS. 4(a) and 4(b). That is, as shown in FIGS. 4(a) and 4(b), the grooves 81g, 82g, 84g, and 94g at two locations on both ends in the width direction of one of the skin plates 84 and 94 among the four skin plates 81 to 84 and 91 to 94 are simultaneously welded in a downward position. Next, the welded and assembled box-shaped cross-sectional members 8 and 9 are turned upside down, and the grooves 81g, 83g, 84g, and 93g at two locations on both ends in the width direction of the skin plates 83 and 93 are simultaneously welded in a downward position.

[0006] The submerged arc welding of such welded and assembled box-shaped cross-sectional members is carried out using equipment capable of performing two-electrode submerged arc welding using a gantry frame. Such equipment needs to be equipped with a movable gantry frame, flux and wire supply equipment, a welding power source, etc., and the equipment is large and expensive. The number of steel fabricators having such equipment is limited, and the hurdle for newly introducing such equipment is also high. Therefore, the current situation is that the supply volume of welded and assembled box-shaped cross-sectional members is tight.

[0007] In addition, since the equipment capable of performing two-electrode submerged arc welding using the above-mentioned gantry frame is installed in the factory of the steel fabricator, there is an upper limit to the steel size that can be accommodated in the gantry frame, and there are restrictions on the size of the welded and assembled box-shaped cross-sectional members that can be manufactured.

[0008] Furthermore, when manufacturing a four-sided welded and assembled box-shaped cross-sectional member, the heat input by two-electrode submerged arc welding reaches a large heat input of up to 500 kJ / cm at maximum. Therefore, the cooling rate of the heat-affected zone and the weld metal becomes extremely slow, which may lead to a decrease in the strength and toughness of the welded and assembled box-shaped cross-sectional member.

[0009] In addition, since the submerged arc welding of the corners of the welded and assembled box-shaped cross-sectional members is performed in a downward welding position, it is necessary to perform the welding of the welded and assembled box-shaped cross-sectional members one side at a time. Further, since the heat input by two-electrode submerged arc welding results in a large heat input, welding deformation is likely to increase. In order to keep this welding deformation within the allowable limit, it is necessary to attach a large number of shape retention plates to the welded and assembled box-shaped cross-sectional members.

[0010] In response to such problems, for example, in Patent Document 1, a method for manufacturing a welded and assembled box-shaped cross-sectional member is proposed in which the welding input is kept low by performing fillet welding on the corners of the welded and assembled box-shaped cross-sectional member from the inside.

Prior Art Documents

Patent Documents

[0011]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0012] However, in the manufacturing method described in Patent Document 1, since it is necessary for a welding operator to perform welding in the inner space of the welded and assembled box-shaped cross-sectional member, the load of the welding work is high and there is a risk of danger in the welding work.

[0013] In view of the above problems, an object of the present invention is to provide a welded and assembled box-shaped cross-sectional member and a manufacturing method thereof that do not require large-scale manufacturing equipment, can suppress the heat input of welding, and can be manufactured with a small number of man-hours.

Means for Solving the Problems

[0014] To solve the above problems, the present invention has the following features.

[0015] [1] A welded assembled box-shaped cross-sectional member formed by performing fillet welding on four skin plates combined so as to have a rectangular cross-section, wherein a first skin plate and a second skin plate are arranged on a pair of opposing surfaces, and a third skin plate and a fourth skin plate are arranged on the other pair of opposing surfaces so as to be sandwiched between the first skin plate and the second skin plate. Openings are provided at both ends in the width direction of the first skin plate, no opening is provided in the second skin plate, and among both ends in the width direction of each of the third skin plate and the fourth skin plate, no opening is provided at one end that is fillet welded to the first skin plate, and an opening is provided on the outer surface side of the welded assembled box-shaped cross-sectional member at the other end that is fillet welded to the second skin plate. By performing fillet welding on each of the openings, the first skin plate to the fourth skin plate are joined to each other. A welded assembled box-shaped cross-sectional member.

[0016] [2] The welded assembled box-shaped cross-sectional member according to [1], wherein each of the openings is a J-shaped opening.

[0017] [3] The welded assembled box-shaped cross-sectional member according to [1] or [2], wherein the fillet welding is partial penetration welding.

[0018] [4] A method for manufacturing the welded assembled box-shaped cross-sectional member according to [1] or [2], wherein the fillet welding is performed on each of the openings by horizontal welding. A method for manufacturing a welded assembled box-shaped cross-sectional member.

[0019] [5] A method for manufacturing the welded assembled box-shaped cross-sectional member according to [3], wherein the fillet welding is performed on each of the openings by horizontal welding. A method for manufacturing a welded assembled box-shaped cross-sectional member.

Advantages of the Invention

[0020] According to the welded assembled box-shaped cross-sectional member and the manufacturing method thereof of the present invention, even if the wall thickness is large, large-scale manufacturing equipment is not required, the heat input amount of welding can be suppressed, and the welded assembled box-shaped cross-sectional member can be manufactured with a small number of man-hours.

Brief Description of the Drawings

[0021]

Figure 1

Figure 2

Figure 3

Figure 4

MODE FOR CARRYING OUT THE INVENTION

[0022] Hereinafter, with reference to the drawings, the welded and assembled box-shaped cross-sectional member of the present invention and a manufacturing method thereof will be described in detail. (First Embodiment) FIG. 1(a) and FIG. 1(b) schematically show a cross-section of the welded and assembled box-shaped cross-sectional member 1 according to the first embodiment of the present invention and its manufacturing situation.

[0023] As shown in FIG. 1(a), the welded and assembled box-shaped cross-sectional member 1 of the first embodiment is formed by performing fillet welding W in a state where four skin plates 11 to 14 are combined so as to have a rectangular cross-section. That is, the skin plates 11 to 14 are long thick steel plates constituting the four sides of the welded and assembled box-shaped cross-sectional member 1. The plate thickness of the skin plates 11 to 14 is about 9 mm to 100 mm, and particularly often 28 mm or more. Further, the skin plates 11 to 14 are often made of a steel type having a strength of 490 N / mm 2 class to 780 N / mm 2 class.

[0024] The skin plates 11 to 14 are composed of a pair of skin plates 11 and 12 arranged in parallel so as to face each other, and another pair of skin plates 13 and 14 arranged in parallel so as to face each other. These two pairs of skin plates 11 to 14 are arranged such that their longitudinal directions are along the material length direction of the welded assembled box-shaped cross-sectional member 1, and are combined to form a rectangular closed cross-section, and are joined to each other by welding at the corners of the welded assembled box-shaped cross-sectional member 1. Specifically, in the welded assembled box-shaped cross-sectional member 1, a first skin plate 11 and a second skin plate 12 are arranged on a pair of opposite surfaces. Further, on another pair of opposite surfaces, a third skin plate 13 and a fourth skin plate 14 are arranged so as to be sandwiched between the first skin plate 11 and the second skin plate 12.

[0025] Also, as shown in FIG. 1(b), both ends in the width direction of the first skin plate 11 are cut obliquely to provide a J-groove 11g. No groove is provided on the second skin plate 12. Further, among both ends in the width direction of the third skin plate 13, no groove is provided at one end (the upper end in FIG. 1(b)) that is fillet-welded to the first skin plate 11, and the other end (the lower end in FIG. 1(b)) that is fillet-welded to the second skin plate 12 is cut obliquely to provide a J-groove 13g. Similarly, among both ends in the width direction of the fourth skin plate 14, no groove is provided at one end (the upper end in FIG. 1(b)) that is fillet-welded to the first skin plate 11, and the other end (the lower end in FIG. 1(b)) that is fillet-welded to the second skin plate 12 has the outer surface side of the welded assembled box-shaped cross-sectional member 1 cut obliquely to provide a J-groove 14g.

[0026] Then, by performing fillet welding W on each of the above-described J-grooves 11g, 13g, and 14g with a welding robot 5 described later, the first to fourth skin plates 11 to 14 are joined to each other to form the welded assembled box-shaped cross-sectional member 1.

[0027] As shown in Fig. 1(b), in the welded and assembled box-shaped cross-sectional member 1 of the first embodiment, each of the above-mentioned groove welds 11g, 13g, and 14g is provided only in a part in the plate thickness direction of the first, third, and fourth skin plates 11, 13, and 14. And as shown in Fig. 1(a), the fillet weld W applied to each of the above-mentioned groove welds 11g, 13g, and 14g is a partial penetration weld that does not reach the opposite surface of the first, third, and fourth skin plates 11, 13, and 14. For this reason, a backing plate is not particularly provided on the back side of the fillet weld W. The penetration depth of the partial penetration weld is determined according to the yield strength required for the welded and assembled box-shaped cross-sectional member 1, but it is preferable to set it to be not less than half of the plate thickness of the skin plate because the risk of fracture of the fillet weld W can be reduced.

[0028] The manufacturing method of the welded and assembled box-shaped cross-sectional member of the present embodiment is a method for manufacturing the above-mentioned welded and assembled box-shaped cross-sectional member 1, which is realized by applying the fillet weld W by horizontal welding to each of the above-mentioned groove welds 11g, 13g, and 14g as shown in Fig. 1(b).

[0029] Fig. 2 schematically shows the welding status of the groove welds 11g, 13g, and 14g in the manufacturing method of the welded and assembled box-shaped cross-sectional member of the first embodiment.

[0030] In the method for manufacturing a welded and assembled box-shaped cross-sectional member according to the first embodiment, various welding methods can be applied as the horizontal welding method. However, as shown in FIG. 2, it is preferable to apply MAG welding or MIG welding by automatic welding using a welding robot 5 that moves along a guide rail 51. By doing so, problems such as difficulty in supplying a welding flux and dripping of the weld metal, which occur when submerged arc welding is applied as the horizontal welding method, do not occur. Since the length of the welded and assembled box-shaped cross-sectional member 1 used as a column member of a building can be nearly 10 m at maximum, the welding lengths of the J-grooves 11g, 13g, and 14g are similarly long, and the work load is high in semi-automatic welding by a welding operator. Therefore, as shown in FIG. 2, by using a welding robot 5 that moves along the guide rails 51 arranged along both sides of the welded and assembled box-shaped cross-sectional member 1, horizontal welding of the four J-grooves 11g, 13g, and 14g can be performed simultaneously, improving workability. And the work load of the welding operator can be reduced, and the welded and assembled box-shaped cross-sectional member 1 can be manufactured with fewer man-hours.

[0031] Here, in horizontal MAG welding or MIG welding, compared with downward submerged arc welding as shown in FIGS. 4(a) and 4(b), the amount of welding in one pass is small, so the number of welding passes may increase. Therefore, as shown in FIG. 1(b), by making the horizontal fillet welds W applied to each of the J-grooves 11g, 13g, and 14g into partial penetration welding as described above, the amount of welding required to join the first to fourth skin plates 11 to 14 to each other can be suppressed. Also, for this reason, it is not necessary to provide a backing bar on the back side of the fillet weld W, and the man-hours required for manufacturing the welded and assembled box-shaped cross-sectional member 1 can be reduced.

[0032] Also, by applying MAG welding or MIG welding, the heat input amount can be made smaller than that of welding methods with a large heat input such as submerged arc welding, and a decrease in the strength and toughness of the heat-affected zone of the fillet weld W and welding deformation can be suppressed.

[0033] Furthermore, in the method for manufacturing the welded and assembled box-shaped cross-sectional member according to the first embodiment, as described above, the horizontal welding of the four V-groove edges 11g, 13g, and 14g can be performed simultaneously. Therefore, unlike submerged arc welding as shown in FIGS. 4(a) and 4(b), after the edges 81g, 82g, 84g, and 94g on one side of the welded and assembled box-shaped cross-sectional members 8 and 9 are welded downward, there is no need to invert the welded and assembled box-shaped cross-sectional members 8 and 9 before welding the edges 81g, 83g, 84g, and 93g on the opposite side downward.

[0034] In addition, by simultaneously performing the horizontal welding of the four V-groove edges 11g, 13g, and 14g, the fillet welds W on both sides of the welded and assembled box-shaped cross-sectional member 1 cannot be symmetrically welded simultaneously. Therefore, compared with the case of adopting downward submerged arc welding, the welding deformation within the welded and assembled box-shaped cross-sectional member 1 can be suppressed. For this reason, even if the number of shape-retaining plates welded within the welded and assembled box-shaped cross-sectional member 1 is reduced to keep the welding deformation within the allowable limit, the amount of deformation can be suppressed to be less than a predetermined magnitude. Thus, the man-hours required for manufacturing the welded and assembled box-shaped cross-sectional member 1 can be reduced.

[0035] Furthermore, in the method for manufacturing the welded and assembled box-shaped cross-sectional member according to the first embodiment, by applying MAG welding or MIG welding, the welded and assembled box-shaped cross-sectional member 1 can be manufactured without introducing large-scale submerged arc welding equipment as described above. Therefore, with a relatively low-cost investment, a new manufacturing line for the welded and assembled box-shaped cross-sectional member 1 can be launched. In addition, the welded and assembled box-shaped cross-sectional member 1 can be manufactured not only within a steel structure factory but also at a construction site. This can reduce the man-hours required for manufacturing the welded and assembled box-shaped cross-sectional member 1 and enable the manufacture of large-sized or special-shaped welded and assembled box-shaped cross-sectional members 1 that could not be manufactured with existing equipment. (Second Embodiment) FIGS. 3(a) and 3(b) schematically show a welded and assembled box-shaped cross-sectional member 2 according to the second embodiment of the present invention and its manufacturing situation.

[0036] As shown in Fig. 3(a), similar to the first embodiment, the welded and assembled box-shaped cross-sectional member 2 of the second embodiment is formed by performing fillet welding W on four skin plates 21 to 24 in a combined state where they have a rectangular cross-section.

[0037] And, as shown in Fig. 3(b), both ends in the width direction of the first skin plate 21 are cut obliquely to provide a J-shaped groove 21g. Also, among both ends in the width direction of the third skin plates 23 and 24, the other ends (the lower ends in Fig. 3(b)) that are fillet welded to the second skin plate 22 are cut obliquely to provide J-shaped grooves 23g and 24g.

[0038] As shown in Fig. 3(b), in the welded and assembled box-shaped cross-sectional member 2 of the second embodiment, each of the above-mentioned J-shaped grooves 21g, 23g, and 24g is provided over the entire thickness direction of the first, third, and fourth skin plates 21, 23, and 24. And, as shown in Fig. 3(a), the fillet welding W performed on each of the above-mentioned J-shaped grooves 21g, 23g, and 24g is a full penetration weld that reaches the opposite side surfaces of the first, third, and fourth skin plates 21, 23, and 24. For this reason, a backing plate 25 is provided on the back side of the fillet welding W.

[0039] The manufacturing method of the welded and assembled box-shaped cross-sectional member of the second embodiment is a method for manufacturing the above-mentioned welded and assembled box-shaped cross-sectional member 2, and as shown in Fig. 3(b), it is realized by performing fillet welding W on each of the above-mentioned J-shaped grooves 21g, 23g, and 24g by horizontal welding.

[0040] According to the welded and assembled box-shaped cross-sectional member and the manufacturing method of the welded and assembled box-shaped cross-sectional member of the second embodiment, the same effects as those of the first embodiment can be obtained.

[0041] In addition, in each of the above-mentioned embodiments, the case where each groove is a J-shaped groove has been described, but the shape of each groove in the welded and assembled box-shaped cross-sectional member and its manufacturing method of the present invention is not limited to this. For example, even when each groove has another shape such as a J-groove, the present invention can be applied and the same effects can be exhibited.

Explanation of Reference Numerals

[0042] 1, 2, 8, 9 Welded and assembled box-section members 11, 21, 81, 91 First skin plates 12, 22, 82, 92 Second skin plates 13, 23, 83, 93 Third skin plates 14, 24, 84, 94 Fourth skin plates 11g, 13g, 14g, 21g, 23g, 24g, 81g, 82g, 83g, 84g, 93g, 94g J-grooves 25, 85, 95 Backing plates W fillet weld 5 Welding robots 51 Guide rails

Claims

1. A welded assembled box-shaped cross-sectional member configured by performing fillet welding in a state where four skin plates are combined to have a rectangular cross-section, wherein a first skin plate and a second skin plate are arranged on a pair of mutually opposing surfaces, and a third skin plate and a fourth skin plate are arranged on the other pair of mutually opposing surfaces so as to be sandwiched between the first skin plate and the second skin plate, wherein openings are provided at both ends in the width direction of the first skin plate, wherein no opening is provided in the second skin plate, wherein, among both ends in the width direction of each of the third skin plate and the fourth skin plate, no opening is provided at one end that is fillet welded to the first skin plate, and an opening is provided on the outer surface side of the welded assembled box-shaped cross-sectional member at the other end that is fillet welded to the second skin plate, a welded assembled box-shaped cross-sectional member in which the first skin plate to the fourth skin plate are joined to each other by performing fillet welding at each of the openings.

2. The welded assembled box-shaped cross-sectional member according to claim 1, wherein each of the openings is a J-shaped opening.

3. The welded assembled box-shaped cross-sectional member according to claim 1 or claim 2, wherein the fillet welding is partial penetration welding.

4. A method for manufacturing the welded assembled box-shaped cross-sectional member according to claim 1 or claim 2, wherein the fillet welding is performed by horizontal welding at each of the openings.

5. A method for manufacturing the welded assembled box-shaped cross-sectional member according to claim 3, wherein the fillet welding is performed by horizontal welding at each of the openings.

Images