Method of welding reinforcing-bar, and reinforcing-bar structure

Abstract

To provide a method of welding reinforcing-bars without moving a tip end of a weld wire.SOLUTION: A method of welding reinforcing-bars 10 includes facing end surfaces 11 of a pair of reinforcing-bars 10 with a clearance Z provided therebetween, placing a ceramic jig 20 having U-shaped cross section with respect to the pair of the reinforcing-bars 10 so as to cover the clearance Z, placing a tip of a weld wire 30 in the clearance Z, and welding the pair of the reinforcing-bars 10 while making a molten pool P in the clearance Z, with the tip of the weld wire 30 separated away from a liquid surface V of the molten pool P.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for welding reinforcing bars and a reinforcing bar structure. [Background technology]

[0002] Patent Document 1 and other publications disclose a technique for welding reinforcing bars together using a ceramic backing material. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent No. 3764272 Summary of the Invention [Problem to be solved by the invention]

[0004] When welding rebars, the arc was brought into contact with the welding point to ensure that the rebar itself was melted. To achieve this, the tip of the welding wire was moved in a square shape while being gradually pulled upward within the gap between the rebars. This ensured that the arc contacted the end faces of the left and right rebars alternately, and the contact point with the arc was also moved in the depth direction of the end faces of the rebars, ensuring that the arc contacted the entire end faces of the left and right rebars. However, with this welding method, the tip of the welding wire needs to be moved within the gap between the end faces of the left and right rebars, so a groove dimension of approximately 10 mm is required. If the groove dimension is smaller than 10 mm, it becomes difficult to move the tip of the welding wire, making it difficult to bring the arc into contact with the end face of the rebar. However, if the groove dimensions are large, a large amount of welding wire must be melted to fill the gaps between the rebars, which increases costs. Furthermore, delicate movements are required to accurately move the tip of the welding wire, which requires skilled work and hinders automation. [Means for solving the problem]

[0005] In order to achieve the above object, the present disclosure provides a method for welding reinforcing bars that allows welding without complex movements of the tip of the welding wire.

[0006] According to the present disclosure, The end faces of the pair of reinforcing bars are arranged facing each other with a gap between them, A ceramic jig with a U-shaped cross section is placed on the pair of reinforcing bars so as to cover the gap, A tip of a welding wire is placed in the gap; A method for welding reinforcing bars is provided, in which a pair of reinforcing bars are welded together while creating a molten pool in the gap and moving the tip of the welding wire away from the liquid surface of the molten pool.

[0007] In the welding method of the present disclosure, The jig is placed on the pair of reinforcing bars so that the U-shaped opening faces upward, The pair of reinforcing bars may be welded together while the tip of the welding wire is being pulled upward.

[0008] According to the present disclosure, The end faces of the pair of reinforcing bars are arranged facing each other with a gap between them, A ceramic jig with a U-shaped cross section is placed on the rebar so as to cover the gap, The welding wire is arranged so that a tip of the welding wire is positioned in the gap and the welding wire extends in a direction intersecting the longitudinal direction of the reinforcing bar; A reinforcing bar welding method is provided in which the pair of reinforcing bars are welded together while melting the welding wire and creating a molten pool in the gap without moving the welding wire.

[0009] In the welding method of the present disclosure, The jig may be placed against the pair of reinforcing bars so that the U-shaped opening faces upward.

[0010] According to the present disclosure, A reinforced concrete structure in which a pair of reinforcing bars are welded at a weld point, A reinforced concrete structure is provided in which the cross section of the reinforcement bar at the welded portion along the longitudinal direction has a uniform structure. [Effects of the Invention]

[0011] According to the present disclosure, a method for welding reinforcing bars is provided that allows welding without complex movements of the tip of the welding wire. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a schematic diagram showing the welding method of this embodiment. [Figure 2] FIG. 2 is a cross-sectional view from the left showing how an arc is generated between the welding wire and the molten pool. [Figure 3] FIG. 3 is a cross-sectional view from the front showing how an arc is generated between the welding wire and the molten pool. [Figure 4] FIG. 4 is a cross-sectional schematic diagram of the structure of a welded portion obtained by a conventional welding method. [Figure 5] FIG. 5 is a cross-sectional schematic diagram of the structure of a welded portion obtained by the welding method of this embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments of the present disclosure will be described in more detail with reference to the drawings. FIG. 1 is a schematic diagram showing a welding method of this embodiment. As shown in FIG. 1, the welding method of this embodiment is a method for welding reinforcing bars 10. The welding method of this embodiment is used when welding opposing ends of a pair of reinforcing bars 10 extending in the longitudinal direction. The welding method of this embodiment can be applied to techniques such as arc welding and TIG welding. The welding method of this embodiment can be applied to a welding method in which power is supplied to a welding wire 30 to generate an arc (ARC) from the welding wire 30.

[0014] First, the end faces 11 of a pair of reinforcing bars 10 are placed opposite each other with a gap Z between them. More specifically, a gap Z is provided between the left end face 11R of the right reinforcing bar 10R located on the right side and the right end face 11L of the left reinforcing bar 10L located on the left side. The distance between the end faces 11 of the pair of reinforcing bars 10 is preferably approximately 1.5 to 12 times the diameter of the welding wire 30. More preferably, the distance between the end faces 11 of the pair of reinforcing bars 10 is approximately 2 to 10 times the diameter of the welding wire 30. In the illustrated example, the pair of reinforcing bars 10 are arranged to extend in the left-right direction. In the following description, the "end face 11 of the reinforcing bar 10" refers to either or both of the left end face 11R of the right reinforcing bar 10R and the right end face 11L of the left reinforcing bar 10L.

[0015] Next, a ceramic jig 20 with a U-shaped cross section is placed on the pair of reinforcing bars 10 so as to cover the gap Z. The jig 20 has a curved portion 21 forming the bottom of the U-shape and two plate-like portions 22 protruding upward from both ends of the curved portion 21. In the illustrated example, the two plate-like portions 22 are plate-like portions extending in the up-down and left-right directions, respectively. The two plate-like portions 22 face each other in the front-to-rear direction. The curved portion 21 extends in the front-to-rear direction so as to connect the lower portions of these two plate-like portions 22. The curved portion 21 is curved so as to be convex downward. To minimize the occurrence of a gap between the inner surface of the jig 20 and the outer peripheral surface of the reinforcing bars 10, it is preferable that the distance between the two plate-like portions 22 of the jig 20 (the distance in the front-to-rear direction in the illustrated example) be slightly larger than the diameter of the reinforcing bars 10. When the jig 20 is placed on a pair of reinforcing bars 10, only the upper part of the gap Z between the pair of reinforcing bars 10 is open, and the front, rear and lower parts of this gap Z are blocked by the jig 20.

[0016] The jig 20 may be held by hand by a worker and positioned so as to cover the gap Z relative to the reinforcing bar 10, or the jig 20 may be maintained attached to the reinforcing bar 10 by the frictional force between the inner surface of the jig 20 and the outer circumferential surface of the reinforcing bar 10. If the worker continues to hold the jig 20 by hand, the worker will continue to hold the jig 20 until the jig 20 is removed in the welding process described below.

[0017] Next, the tip of the welding wire 30 is placed in this gap Z. The welding wire 30 is inserted from above into the gap Z until the tip of the welding wire 30 is positioned within the gap Z.

[0018] Once the tip of the welding wire 30 is positioned within the gap Z, current is passed through the welding wire 30 to generate an arc ARC between the welding wire 30 and the end face 11 of at least one of the reinforcing bars 10. For the sake of explanation, it is assumed here that an arc ARC is generated between the left end face 11R of the right reinforcing bar 10R and the welding wire 30. The arc ARC then melts the left end face 11R of the right reinforcing bar 10R and the welding wire 30, and a molten pool P accumulates on the upper surface of the curved portion 21 of the jig 20. An arc ARC is generated between the left end face 11R of the right reinforcing bar 10R and the welding wire 30 until the molten pool P accumulates from the left end face 11R of the right reinforcing bar 10R to the right end face 11L of the left reinforcing bar 10L. If the distance between the pair of reinforcing bars 10 is sufficiently short, an arc ARC may be generated between the welding wire 30 and the end faces 11 of both reinforcing bars 10 from the beginning, and the end faces 11 of both reinforcing bars 10 may be melted.

[0019] When the molten pool P is sufficiently formed so that it accumulates from the left end face 11R of the right rebar 10R to the right end face 11L of the left rebar 10L, an arc ARC is generated between the welding wire 30 and the molten pool P. This heats the molten pool P to a high temperature. Figures 2 and 3 are schematic diagrams showing this state. Figure 2 is a cross-sectional view from the left showing the state in which the arc ARC is generated between the welding wire 30 and the molten pool P, and Figure 3 is a cross-sectional view from the front.

[0020] As shown in Figure 3, when the molten pool P is sufficiently heated, both the left end surface 11R of the right rebar 10R and the right end surface 11L of the left rebar 10L, which are in contact with the high-temperature molten pool P, melt. When the end surfaces 11 of both rebars 10 melt and flow into the molten pool P, the liquid level V of the molten pool P rises. Therefore, as the liquid level V of the molten pool P rises, the tip of the welding wire 30 is moved away from the liquid level V of the molten pool P so as to maintain a state in which an arc ARC is generated between the liquid level V of the molten pool P and the tip of the welding wire 30.

[0021] According to the welding method of the present disclosure, the reinforcing bar 10 is melted by the molten pool P, so the tip of the welding wire 30 only needs to be pulled straight up above the liquid surface V of the molten pool P. In other words, there is no need to move the welding wire 30 along the end face 11 of the reinforcing bar 10 or to alternately bring the welding wire 30 close to the end faces 11 of the left and right reinforcing bars 10, so welding can be performed without complex movements of the tip of the welding wire 30.

[0022] The molten pool P can be kept sufficiently heated by adjusting the current supplied to the welding wire 30 and the rising speed of the welding wire 30. Furthermore, it is preferable to make the groove dimensions smaller as the diameter of the reinforcing bar 10 to be welded increases. This is because as the diameter of the reinforcing bar 10 increases, the cross-sectional area of ​​the reinforcing bar 10 increases, causing heat to dissipate from the molten pool P to the reinforcing bar 10, making it difficult to maintain the molten pool P at a high temperature.

[0023] Furthermore, according to the welding method of the present disclosure, the end faces 11 of the reinforcing bars 10 are not melted directly by the welding wire 30, but are melted by the molten pool P formed by the welding wire 30. Therefore, even if the welding wire 30 is spaced a large distance from the end faces 11 of both reinforcing bars 10 in consideration of workability, the end faces 11 of both reinforcing bars 10 can be heated simultaneously.

[0024] The state in which an arc ARC is generated between the tip of the welding wire 30 and the molten pool P is maintained until the gap Z is completely filled with the molten pool P. Thereafter, the current to the welding wire 30 is stopped, the jig 20 is removed, and the welding is completed when the molten pool P has sufficiently cooled and solidified. Note that if the jig 20 is stuck to the welded location where the molten pool P has solidified, the jig 20 may be broken and removed.

[0025] As described above, the welding method for the reinforcing bar 10 of this embodiment is as follows: The end faces 11 of the pair of reinforcing bars 10 are arranged to face each other with a gap Z therebetween, A ceramic jig 20 having a U-shaped cross section is placed on the pair of reinforcing bars 10 so as to cover the gap Z, The tip of the welding wire 30 is placed in the gap Z, A pair of reinforcing bars 10 are welded together while forming a molten pool P in the gap Z and keeping the tip of the welding wire 30 away from the liquid surface V of the molten pool P.

[0026] The welding method for reinforcing bars 10 of this embodiment generates an arc ARC between the welding wire 30 and the molten pool P, eliminating the need to move the tip of the welding wire 30 back and forth between both end surfaces 11 of a pair of reinforcing bars 10. In other words, the operation is extremely simple, as it is sufficient to simply pull the tip of the welding wire 30 upward, eliminating the need for complex movements of the welding wire 30. Therefore, while welding work previously required skill, any worker with a certain level of skill can easily perform the welding work. Furthermore, the welding method for reinforcing bars 10 of this embodiment is highly suitable for automated welding using robots, etc.

[0027] Further, the welding method for the reinforcing bar 10 of this embodiment is as follows: The jig 20 is placed on the pair of reinforcing bars 10 so that the U-shaped opening faces upward. The pair of reinforcing bars 10 are welded together while the tip of the welding wire 30 is pulled upward. According to this method, the molten pool P tends to accumulate at the bottom of the U-shaped jig 20.

[0028] The structure of the weld (the portion where the molten pool P has solidified) obtained by the welding method of this embodiment differs from the structure of the weld obtained by a conventional welding method in which the welding wire 30 is moved back and forth between the end faces 11 of a pair of reinforcing bars 10. Fig. 4 is a cross-sectional schematic diagram of the structure of the weld obtained by the conventional welding method, and Fig. 5 is a cross-sectional schematic diagram of the structure of the weld obtained by the welding method of this embodiment.

[0029] As shown in Figure 4, in the conventional welding method, the tip of the welding wire 30 is brought close to the left end face 11R of the right rebar 10R in order to melt the left end face 11R of the right rebar 10R. Then, the tip of the welding wire 30 moves away from the right end face 11L of the left rebar 10L, and no arc ARC is generated between them. Therefore, while the left end face 11R of the right rebar 10R is melting, the right end face 11L of the left rebar 10L does not melt, so a molten pool P is formed between the left end face 11R of the right rebar 10R and the welding wire 30. Furthermore, the molten pool P is hot near the left end face 11R of the right rebar 10R, but cold near the right end face 11L of the left rebar 10L, so the portion of the molten pool P near the right end face 11L of the left rebar 10L solidifies. Therefore, as shown in Figure 4, the structure of the welded area obtained by the conventional welding method is a laminate of a first structure A1 derived from the left end surface 11R of the right reinforcing bar 10R, which is thicker on the right side, and the welding wire 30, and a second structure A2 derived from the right end surface 11L of the left reinforcing bar 10L, which is thicker on the left side, and the welding wire 30.

[0030] 5, the structure of the welded portion obtained by the welding method of this embodiment is such that the molten pool P simultaneously melts both the left end surface 11R of the right reinforcing bar 10R and the right end surface 11L of the left reinforcing bar 10L, and therefore the molten pool P is formed of a single structure A derived from the left end surface 11R of the right reinforcing bar 10R, the right end surface 11L of the left reinforcing bar 10L, and the welding wire 30. In this way, the reinforced concrete structure obtained by the welding method of this embodiment, in which a pair of reinforcing bars 10 are welded at the welded portion, has a uniform structure A in the cross section along the longitudinal direction of the reinforcing bars 10 at the welded portion.

[0031] When an arc ARC is generated between the tip of the welding wire 30 and the molten pool P, the welding wire 30 itself also melts, so the tip position of the welding wire 30 gradually rises without the need to pull up the welding wire 30 itself. Therefore, if the diameter of the welding wire 30, the diameter of the reinforcing bar 10, the distance of the gap Z, and the like are adjusted so that the rate of rise of the liquid level V of the molten pool P and the rate of rise of the tip position of the welding wire 30 are balanced, an arc ARC can be continuously generated between the tip of the welding wire 30 and the molten pool P without moving the welding wire 30. The welding method for the reinforcing bar 10 in such a case can also be expressed as follows.

[0032] A method for welding reinforcing bars (10), comprising: The end faces 11 of the pair of reinforcing bars 10 are arranged to face each other with a gap Z therebetween, A ceramic jig 20 having a U-shaped cross section is placed on the reinforcing bar 10 so as to cover the gap Z, The welding wire 30 is arranged so that the tip of the welding wire 30 is positioned in the gap Z and the welding wire 30 extends in a direction intersecting the longitudinal direction of the reinforcing bar 10; The pair of reinforcing bars 10 are welded together while the welding wire 30 is melted and a molten pool P is formed in the gap Z without moving the welding wire 30. According to this welding method, the welding wire 30 does not need to be moved, so that welding can be performed more easily.

[0033] Although the embodiments of the present invention have been described above, it goes without saying that the technical scope of the present invention should not be construed as being limited by the description of the present embodiments. The present embodiments are merely examples, and it will be understood by those skilled in the art that various modifications of the embodiments are possible within the scope of the invention described in the claims. The technical scope of the present invention should be determined based on the scope of the invention described in the claims and its equivalents. [Explanation of symbols]

[0034] 10 Reinforced concrete 10L Left rebar 10R Right Rebar 11 End face 11L Right end surface 11R Left end surface 20 Jig 21 music section 22 Plate-shaped part 30 welding wire A organization A1 First Organization A2 Second organization ARC P molten pool V liquid level Z gap

Claims

1. The end faces of a pair of rebars are placed facing each other with a gap between them, A ceramic jig having a U-shaped cross section is placed on the pair of reinforcing bars so as to cover the gap, A tip of a welding wire is placed in the gap; A reinforcing bar welding method in which a pair of reinforcing bars are welded together while creating a molten pool in the gap and moving the tip of the welding wire away from the liquid surface of the molten pool.

2. The jig is placed on the pair of reinforcing bars so that the U-shaped opening faces upward, The welding method according to claim 1 , wherein the pair of reinforcing bars are welded together while pulling the tip of the welding wire upward.

3. The end faces of a pair of rebars are placed facing each other with a gap between them, A ceramic jig with a U-shaped cross section is placed on the reinforcing bar so as to cover the gap, The welding wire is arranged so that a tip of the welding wire is positioned in the gap and the welding wire extends in a direction intersecting the longitudinal direction of the reinforcing bar; The reinforcing bar welding method includes welding the pair of reinforcing bars while melting the welding wire and forming a molten pool in the gap without moving the welding wire.

4. The welding method according to claim 3 , wherein the jig is placed against the pair of reinforcing bars so that the openings of the U-shape face upward.

5. A reinforced concrete structure in which a pair of reinforcing bars are welded at a weld point, A reinforced concrete structure in which the cross section of the welded portion along the longitudinal direction of the reinforcement bar has a uniform structure.

Images