JP2002346745A - Backing metal for connecting reinforcing bar - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a backing metal for connection that does not overlook occurrence of insufficient connecting strength in CO2 gas shielded arc welding by visually confirming the welding condition of a lower part and back side between reinforcing bars after the welding. SOLUTION: A peep hole 2 is arranged at the backing metal 1 in which end of reinforcing bars A, A to be joined to each other by CO2 gas shielded arc welding is fitted, the peep hole 2 is then blocked with a removable heat resistant member 3 the heat resistant member 3 is removed after the welding and the weld zone can be visually inspected through the peep hole 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a connecting back metal used for joining ends of reinforcing bars to each other by carbon dioxide arc welding.

[0002]

2. Description of the Related Art In various types of rebar used for construction of a rebar structure, a connection by semi-automatic carbon dioxide arc welding is adopted as a method for connecting the ends of the rebar in an extended manner.

[0003] This semi-automatic carbon dioxide gas arc welding has a cross section U
Using metal back metal formed in a letter shape, the ends of the reinforcing bars to be connected to each other are fitted into this back metal, and both the reinforcing bars and the back metal are temporarily fixed by spot welding, and then the opposite ends of both reinforcing bars are joined. Both rebars are connected by welding by carbon dioxide arc welding. In addition, the reinforcing bars may be arranged not only horizontally but also vertically.When the reinforcing bars are horizontal, the back metal is placed below the reinforcing bars, but when the reinforcing bars are vertical, the back metal is placed behind the reinforcing bars. Will be.

[0004] The back metal used at the time of welding has a role of positioning the reinforcing bars to be connected to each other, preventing leakage of the molten material, and preventing leakage of carbon dioxide gas, and remains attached to the reinforcing bars after welding of the reinforcing bars.

[0005] By the way, in carbon dioxide arc welding of rebar, in order to obtain a predetermined connection strength, it is necessary to bond the entire area of the end face of the rebar with a molten material, and it is necessary to confirm whether the welding is performed reliably. , A visual inspection must be performed.

[0006]

However, the lower and back sides of the welded portions of the connected reinforcing bars are covered with backing metal, and the lower and back sides of the welded portions cannot be visually inspected from the outside.

[0007] In particular, in the welding of the rebar, the molten material is introduced from the upper side or the near side between the opposing end faces of the rebar.
In many cases, a state in which the molten material does not flow into the lower portion between the end surfaces and the back side occurs. For this reason, even if it is completely welded in the state seen from the top or the front, the molten material may not wrap around to the lower part or the back side between the end faces, and in such a state,
As a result, a predetermined welding strength cannot be obtained, which causes an inconvenience in the construction of the reinforcing steel structure.

Therefore, an object of the present invention is to make it possible to visually confirm the welding state of the lower portion between the end faces and the back side after welding of a reinforcing bar, and to prevent the occurrence of insufficient connection strength in carbon dioxide gas arc welding of the reinforcing bar. An object of the present invention is to provide a backing metal for connection that can be visually inspected without being missed.

[0009]

According to a first aspect of the present invention, a window hole is provided in a back metal in which ends of rebars to be connected to each other by carbon dioxide arc welding are fitted. This adopts a configuration in which the hole is closed by a heat-resistant member that can be removed.

After welding the rebar, if the heat-resistant member attached to the back metal is removed and the window hole is opened, the welded portion of the rebar can be visually inspected from below or from behind.

A second aspect of the present invention employs a configuration in which a window hole is provided in a back metal into which ends of reinforcing bars to be connected to each other are connected by carbon dioxide arc welding, and the window hole is closed with a heat-resistant breakable member. It is.

After the rebar is welded, if the breakable member attached to the back metal is broken and the window is opened, the welded portion of the rebar can be visually inspected from below or from behind.

In these inventions, the heat-resistant member and the breakable member are made of ceramic, and when used as a heat-resistant member, may be adhered and fixed from outside so as to cover the window hole. In the case of a breakable member, the same heat-resistant member as the above-mentioned heat-resistant member is fixed or incorporated in a window hole inside the back metal.

[0014] An enlarged diameter portion is preliminarily machined at the ends of the reinforcing bars to be connected to each other by the carbon dioxide arc welding.
The welding area can be enlarged to improve the connection strength, and the back metal can be formed so that the end faces of the enlarged diameter portions of both rebars are opposed to each other.

[0015]

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

The first embodiment shown in FIG. 1 and FIG. 2 shows a connecting back metal for welding rebars A, A having straight ends, and the back metal 1 using a metal plate is The back metal 1 is formed in a U-shaped cross section in which the end of A is accommodated.

A heat-resistant member 3 for closing the window hole 2 is attached to the outer surface of the back metal 1. This heat resistant member 3
Is made of a heat-resistant material such as ceramic or metal,
And a flange portion 3b provided so as to protrude around the outside of the fitting portion 3a and overlapping the outer surface of the back metal 1. The fitting portion 3a is formed from the flange portion 3b. The protruding thickness is equal to the thickness of the back metal 1, and is formed in an arc shape such that the inner surface thereof matches the curvature of the inner surface of the back metal 1 when fitted to the window hole 2.
a is pressed into the window hole 2 or the flange portion 3 b is adhered to the outer surface of the back metal 1 to be attached to the back metal 1.

In order to weld the reinforcing bars A, A using the back metal 1 of the first embodiment, as shown in FIG.
Is fitted in the window hole 2, and a heat-resistant member 3 is attached to the outer surface of the back metal 1 so as to close the window hole 2, and both ends of the reinforcing bars A, A are fitted into the inside of the back metal 1, and both reinforcing bars A, A After the two rebars A, A and the backing metal 1 are temporarily fixed by spot welding with a predetermined interval secured on the end surfaces of the two rebars A, A, the opposite ends of the two rebars A, A are welded with a filler material B by carbon dioxide arc welding. Connect with

After this welding, in order to confirm the welding state of the lower part, the heat resistant member 3 is removed from the outer surface of the back metal 1 and the window hole 2 is opened. When the heat-resistant member 3 is formed of a breakable material such as ceramic, the heat-resistant member 3 may be detached from the back metal 1 by being broken by applying an external impact.

As described above, by removing the heat-resistant member 3 and opening the window hole 2, both sides from the lower part of the welded portion can be visually inspected from this window hole portion. The connection which cannot obtain a predetermined welding strength due to the shortage can be eliminated.

Next, a second embodiment shown in FIGS. 3 and 4 shows a connecting back metal for welding rebars A, each of which has an enlarged diameter portion a formed at an end in advance. The enlarged diameter portion a is
The end portion of the reinforcing bar A is coldly pressed in the axial direction to form a substantially hemispherical shape having a flat end surface, or the end portion of the reinforcing bar A is pressed in the axial direction in a state where the end portion is heated at a high frequency to have the same shape as above. For example, the diameter of the enlarged diameter portion a is increased such that the end face has an area of 1.2 times or more the cross-sectional area of the reinforcing bar A.

The back metal 11 has a structure in which both enlarged diameter portions a are accommodated, has a U-shaped cross section in which the reinforcing bars A, A are just accommodated, and has an arc-shaped bulging portion extending outward at a central portion in the longitudinal direction. 12
Is formed over the entire circumference in the circumferential direction, and the enlarged diameter portions a of both rebars A, A are accommodated in the arc-shaped bulging portion 12 with a predetermined interval kept between the facing surfaces. In addition, this back metal 11 omits a U-shaped section in which the reinforcing bars A, A just fit, separately from the illustration, and the arc-shaped bulging portion 1 outwardly of the central portion.
It is also possible to have only two structures.

A window hole 13 is provided at a central position of the arc-shaped bulging portion 12 of the back metal 11, and an outer surface of the back metal 11 has a heat-resistant closing the window hole 13 as in the first embodiment. Sex member 3 is attached. The heat-resistant member 3 includes a fitting portion 3a for fitting into the window hole 13 and a fitting portion 3a.
and a flange portion 3b provided so as to protrude around the outer periphery of the fitting portion 3a and overlapping the outer surface of the back metal 11.
The inner surface of a is formed in an arc shape so as to match the curvature of the inner surface of the arc-shaped bulging portion 12.

In order to connect the reinforcing bars A, A using the back metal 11 of the second embodiment, the window hole 13 of the back metal 11 is closed with the heat-resistant member 3 and the enlarged diameter portion is previously provided at the end. a into the back metal 11 and the arcuate bulge 12
The enlarged diameter portions a to be accommodated in the inside are set in a state where a predetermined interval is provided between the end surfaces thereof, and in this state, the end surfaces of the enlarged diameter portions a facing each other are welded by the molten material B.

In the above welding, the ends of both rebars A, A have an enlarged area due to the end face of the enlarged diameter portion a.
The joint area with the welding material B is increased, and the connection strength of the reinforcing bars A, A is improved by that much. The visual inspection of the welded portion is performed by using the heat-resistant member 3 in the same manner as in the first embodiment. It may be performed by removing and opening the window hole 13.

The connection back metal according to the third embodiment shown in FIGS. 5 and 6 is an example in which a window hole 22 provided at a central portion of the back metal 21 is closed by a breakable member 23 such as ceramic. By forming concave steps 24 on both sides of the window hole 22 on the inner surface of the back metal 21 and fitting both sides of a breakable member 23 having a planar size and a plate thickness suitable for the window hole 22 to the concave steps 24. , The window hole 22 is closed. The breakable member 23 includes:
The inner surface is formed in an arc shape matching the curvature of the inner surface of the back metal 21.

The back metal according to the third embodiment can be used for welding rebars A having straight ends, as in the first embodiment, or as in the second embodiment. May have an arc-shaped bulging portion for welding the reinforcing bars A, A having a large diameter portion a formed in advance at the end.

In order to connect the reinforcing bars A, A using the back metal 21 of the third embodiment, the concave step 2 is formed on the inner surface of the back metal 21.
4 with the breakable member 23 fitted therein,
Alternatively, the visual inspection of the welded portion can be performed by tapping the breakable member 23 from outside after welding, removing the broken portion, and opening the window hole 22 after welding.

In any of the embodiments, the reinforcing bar A may be a deformed reinforcing bar, and the illustrated example shows that the reinforcing bars A, A are welded in a horizontal state, but the reinforcing bars A, A are arranged vertically. In this case, the visual inspection of the welded portion is performed from the back side of the back metal.

[0030]

As described above, according to the present invention, a window hole is provided in the back metal in which the ends of both reinforcing bars to be connected to each other are fitted, and this window hole is closed by a heat-resistant member or a breakable member. By removing the heat-resistant member or breakable member after welding and opening the window hole, it becomes possible to visually inspect the welding state from the bottom and the back side after welding the reinforcing bar, and in the carbon dioxide gas arc welding of the reinforcing bar, the connection by welding The occurrence of the lack of strength is not overlooked, and the connection of the reinforcing bars can be obtained without causing any inconvenience to the construction of the reinforcing bar structure.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a connection back metal according to a first embodiment.

FIG. 2 is a longitudinal sectional front view of a reinforcing bar connection state using the connection backing metal.

FIG. 3 is a perspective view showing a connection back metal according to a second embodiment;

FIG. 4 is a longitudinal sectional front view of a reinforcing bar connection state using the connection back metal.

FIG. 5A is a longitudinal sectional front view showing a state where a reinforcing bar is connected using a connection backing metal of the third embodiment, and FIG. 5B is a longitudinal sectional side view of the same.

FIG. 6 is a perspective view showing a connection back metal according to a third embodiment;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 back metal 2 window hole 3 heat-resistant member 11 back metal 12 arc-shaped bulging portion 13 window hole 21 back metal 22 window hole 23 breakable member 24 concave step portion A reinforcing bar B molten material a enlarged diameter portion

Claims (3)

[Claims] A back metal for connecting a reinforcing bar, wherein a window hole is provided in a back metal into which ends of reinforcing bars to be connected to each other by carbon dioxide arc welding are fitted, and the window hole is closed with a removable heat-resistant member. 2. A back metal for connecting a reinforcing bar, wherein a window hole is provided in a back metal into which ends of reinforcing bars to be connected to each other by carbon dioxide arc welding are fitted, and the window hole is closed by a heat-resistant breakable member. 3. An enlarged diameter portion is formed in advance on the ends of the reinforcing bars to be connected to each other by carbon dioxide arc welding, and the back metal is formed so that the end surfaces of the enlarged portions of both the reinforcing bars are opposed to each other. The back metal for connecting a reinforcing bar according to claim 1 or 2.