JP2001212667A - Welding joint method for reinforcing steel bar - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a welding joint method which prevents the reinforcing bar from cooling rapidly in joint welding by CO2 gas arc welding, controlling the hardness of reinforcing bar's ends, thereby improving bendability, achieves excellent quality and performance in welding, and which is easy for an ultrasonic defect inspection after welding. SOLUTION: When the reinforcing steel bar is welded by semi-automatic CO2 gas arc welding, using metallic U-shaped joint sleeve 2, the welding part of the reinforcing bar is heated until about 300-450 deg.C temperature by a high frequency electro-magnetic heater 3 prior to welding. Soon after that, a windshield for preventing CO2 gas leakage, and inorganic insulation are attached to the welding part of the reinforcement bar 1.1. After that, the reinforcement bar 1.1 is welded by semi-automatic CO2 gas arc welding.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for welding joints of rebar by semi-automatic carbon dioxide gas arc welding in the rebar work of civil engineering and building works.

[0002]

2. Description of the Related Art Conventionally, gas pressure welding has been frequently used for joint welding of reinforcing bars in civil engineering and construction work.
The joint welding method by carbon dioxide arc welding has been adopted.

[0003] The joint welding method by carbon dioxide arc welding uses a U-shaped joint sleeve made of a steel plate to prevent the leakage of carbon dioxide gas and the role of a backing plate for welding, and to form reinforcing bars for connecting to each other in the joint sleeve. The ends are fitted, the ends of the reinforcing bars are welded by carbon dioxide arc welding, and the reinforcing bars are connected to each other.

[0004]

By the way, in the carbon dioxide gas arc welding method, the end temperature of the reinforcing bar is usually about 1500 ° C. to 1600 ° C. by welding, and the welded portion is left to cool in a natural atmosphere when cooled. Quenched.
In the cold season and in strong winds, it will be cooled more rapidly.

[0005] Usually, in a tensile test of a welded portion, the base metal rebar breaks and sufficient strength is obtained in the welded portion.
In the 90 ° bending test, the vicinity of the weld may be damaged.

[0006] Experiments have revealed that this is because the end region of the base metal rebar is quenched by rapid cooling, and the hardness of the quenched portion is increased and the portion is easily broken.

As described above, the conventional joint welding method using carbon dioxide arc welding has a problem that the bendability of a welded portion is reduced.

Further, it is necessary to inspect the welded portion of the reinforcing bar for defects by ultrasonic inspection. If the joint sleeve is long, the joint sleeve existing around the welded portion of the reinforcing bar hinders the inspection. However, there is a problem that flaw detection is difficult to perform.

Accordingly, an object of the present invention is to prevent quenching of a reinforcing bar at the time of joint welding by carbon dioxide gas arc welding and to suppress an increase in hardness at the end of the reinforcing bar, thereby improving bendability and obtaining welding with excellent quality and performance. Accordingly, it is an object of the present invention to provide a rebar welded joint construction method capable of easily performing flaw detection inspection by ultrasonic waves after welding.

[0010]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the invention according to claim 1 uses a metal U-shaped joint sleeve to weld a reinforcing bar by semi-automatic carbon dioxide welding. Welded parts with high-frequency electromagnetic heater
Preheating to the required temperature according to the rebar diameter, immediately after that, attach a windshield hood with a function to prevent leakage of carbon dioxide gas to the rebar to be welded, and then weld the rebar by semi-automatic carbon dioxide welding. It has been adopted.

According to a second aspect of the present invention, in accordance with the first aspect of the present invention, the welding of the reinforcing bar by the semi-automatic carbon dioxide welding is performed in such a manner that the welded portion of the reinforcing bar is wrapped inside the windshield hood, and the inorganic insulating material has a welding opening. The welding is performed in a state in which the material is filled, and a quenching effect due to rapid cooling of the welded portion is prevented by the inorganic heat insulating material, and a configuration is employed in which the bendability of the welded portion is ensured.

According to a third aspect of the present invention, in the first or second aspect of the present invention, the metal U-shaped joint sleeve has a length of about 2.5 times an end face interval of a reinforcing bar to be welded, Circumferential slits are provided at two positions outside the end face spacing of the reinforcing bar, and after completion of the welding of the reinforcing bar by semi-automatic carbon dioxide welding, the portion outside the slit of the joint sleeve is removed to enable welding by ultrasonic waves. This configuration employs a configuration that enables a partial flaw detection inspection.

[0013]

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

As shown in the drawing, the rebar welding joint method of the present invention is implemented by using a metal U-shaped joint sleeve 2 which elastically fits on the rebars 1 and 1 to be welded, and a rebar 1 and a rebar 1.
(1) a portable high-frequency electromagnetic heater 3 for preheating the welded portion, a windshield hood 4 having a function of preventing the leakage of carbon dioxide gas, and a quenching effect by quenching the welded portion so as to enclose the rebar welded portion. An inorganic heat insulating material 5 for prevention and semi-automatic carbon dioxide gas arc welding means are used.

The joint sleeve 2 has a length approximately 2.5 times the end face interval (weld route interval) H of the reinforcing bars 1 and 1 to be welded. Two circumferential slits 6 are provided at the two positions from both sides, so that portions outside the slit 6 can be cut off and removed.

The high-frequency electromagnetic heater 3 is provided with a handle 8 on the upper surface of a U-shaped heating section 7 which is fitted to the reinforcing bars 1 and 1 to be welded from above, and is incorporated in the heating section 7. 9 is connected to a power source through a cord 10 drawn out of a handle 8 to heat the portions of the reinforcing bars 1 and 1 to be welded by high-frequency electromagnetic heating. To pre-heat the welded portions of the reinforcing bars 1 and 1 to a required temperature according to the type of steel and the diameter of the reinforcing bars, for example, about 300 ° C. to 450 ° C.

The windshield hood 4 comprises a pair of half-boxes 11 and 12 made of a heat-resistant material.
2 has a peripheral wall 13 and a bottom wall 14 formed of three surfaces, and both ends of the fitted peripheral wall 13 are connected to each other with a pin 15;
At the edge of both peripheral walls 13, a semicircular cutout 16 is formed to be fitted to the reinforcing bar 1 when closed, and when closed, a rectangular container shape with a lower constriction having an open upper part and a closed lower part. Becomes
At the time of opening, by opening both half-boxes 11 and 12 outward with the pin 15 as a fulcrum, the bottom wall 14 is separated and the edges of both peripheral walls 13 are shaped like a letter C, and can be freely attached to and detached from the reinforcing bars 1, 1. become.

The pair of half boxes 11 and 12 are
The elasticity in the direction of closing each other is urged by a spring 17 stretched between them.

The inorganic heat insulating material 5 is formed as a slow cooling pad that fills the inside of the windshield hood 4 in such a manner as to wrap the welded portion of the reinforcing bar, and is provided with a welding opening 5a.

Next, the construction method of the rebar welding joint method will be described.

As shown in FIG. 1 and FIG.
The heating part 7 of the high-frequency electromagnetic heater 3 is externally fitted from above the rebars 1 and 1 to the coil 9 in a state where the ends of the rebars 1 and 1 are fitted with an end face interval H secured therein. The welding of the rebars 1 and 1 is preliminarily heated to about 300 ° C. to 450 ° C. by electromagnetic waves. At this time, the ends of both reinforcing bars 1, 1 are located inside the slit 6 of the joint sleeve 2.

The high-frequency electromagnetic heater 3 for performing the preceding heating
Is configured to set a heating time according to the steel type and diameter of the reinforcing bar 1 with respect to a constant heating current value, and to display an alarm by detecting a condition of heating to a predetermined temperature by a sensor.

Immediately after the end of the preheating, as shown in FIG. 8, a pair of open half-boxes 11 and 12 are inserted into portions of the reinforcing bars 1 and 1 to be welded, and the notch 16 is
By closing the half-boxes 11 and 12 in a state of facing the windshield 1, the windshield hood 4 having a function of preventing leakage of carbon dioxide gas is mounted, and then, as shown in FIGS. An inorganic heat insulating material 5 having an opening 5a is filled in such a manner as to wrap the welded portion of the reinforcing bars 1, 1, and thereafter, the ends of the reinforcing bars 1, 1 are welded with the welding material A by carbon dioxide arc welding.

At this time, since the ends of the reinforcing bars 1 and 1 are preheated, carbon dioxide arc welding can be performed efficiently, and the welded portion is protected by the windshield hood 4 from strong wind and cold wind. Because it is surrounded by
Prevents leakage of carbon dioxide.

When welding the reinforcing bars 1 and 1 by semi-automatic carbon dioxide gas arc welding, as shown in FIGS. 4 to 6, an inorganic heat insulating material 5 having a welding opening 5a is provided inside the windshield hood 4 to form the reinforcing bars 1 and 1. By filling the welded part in a manner that wraps around it, quenching action due to rapid cooling of the welded part can be prevented, the bendability of the welded part can be ensured and the quality and performance of the rebar welded part can be improved .

When a certain time has elapsed after the completion of the welding, the inorganic heat insulating material 5 is taken out from the welded portion, and then the windshield hood 4 is removed and collected, and then used again for the next welding.

After the welding of the rebar is completed, as shown in FIG. 9, by removing the portion of the joint sleeve 2 outside the slit 6, the joint sleeve 2 is shortened and the rebar 1,
Since the amount of overlap with the outer surface of 1 is reduced and does not hinder the welding inspection by ultrasonic waves, the inspection can be easily performed.

[0028]

As described above, according to the present invention, a welded portion of a reinforcing bar is preheated by a high-frequency electromagnetic heater, and immediately thereafter, a windshield hood having a function of preventing leakage of carbon dioxide gas is attached to the reinforcing bar. Since the rebar is welded by semi-automatic carbon dioxide welding after mounting, semi-automatic carbon dioxide welding can be performed efficiently by preheating the rebar, and the windshield hood prevents leakage of carbon dioxide during welding work. In addition, it is possible to maintain the antioxidant effect of carbon dioxide on the welded portion, and thereby obtain a welded bar with excellent quality and performance.

Immediately after welding the reinforcing bar, the windshield hood is filled with an inorganic heat insulating material so as to wrap the welded portion of the reinforcing bar, thereby preventing the quenching effect due to rapid cooling of the welded portion. Flexibility can be ensured.

Further, circumferential slits are provided at two positions of the metal U-shaped joint sleeve, and after the rebar welding by the semi-automatic carbon dioxide welding is completed, a portion outside the slit of the joint sleeve is removed. In addition, it is possible to perform a welding inspection by ultrasonic waves.

[Brief description of the drawings]

FIG. 1 is a front view of a pre-heated state showing a rebar welding joint method.

FIG. 2 is a longitudinal sectional side view of the above.

FIG. 3 is a perspective view of a joint sleeve.

FIG. 4 is a vertical front view showing a reinforcing bar welding state of a reinforcing bar welding joint method equipped with a windshield hood and an inorganic heat insulating material.

FIG. 5 is a plan view of the above.

FIG. 6 is a longitudinal sectional side view of the above.

FIG. 7 is a perspective view showing an opened state of the windshield hood.

FIG. 8 is a perspective view showing a state in which a windshield hood is attached to a reinforcing bar.

FIG. 9 is a front view showing partial removal of the joint sleeve after reinforcing bar welding.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rebar 2 Joint sleeve 3 High-frequency electromagnetic heater 4 Windshield hood 5 Inorganic heat insulating material 5a Welding opening 6 Slit

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) E04G 21/12 105 E04G 21/12 105E H05B 6/10 331 H05B 6/10 331 F term (reference) 3K059 AA09 AB14 AB24 AB28 AC01 AC33 AC35 AC77 AD03 AD28 AD34 CD44 CD52 4E001 AA03 BB09 CC04 DG03 4E081 AA08 BA48 CA10 DA31 EA37 YB10

Claims (3)

[Claims] When welding a reinforcing bar by semi-automatic carbon dioxide welding using a metal U-shaped joint sleeve, the welded portion of the reinforcing bar is preheated by a high-frequency electromagnetic heater to a required temperature according to the steel type and the reinforcing bar diameter. Immediately thereafter, a windshield hood having a function of preventing leakage of carbon dioxide gas is attached to the reinforcing steel to be welded, and subsequently the reinforcing steel is welded by semi-automatic carbon dioxide welding. 2. A method for welding a reinforcing bar by the semi-automatic carbon dioxide welding in a state where the reinforcing bar welding portion is wrapped in a windshield hood and filled with an inorganic insulating material having a welding opening. The method according to claim 1, wherein the quenching of the welded portion is prevented by quenching to secure the bending property of the welded portion. 3. The metal U-shaped joint sleeve has a length of about 2.5 times the end face interval of the reinforcing bar to be welded, and is provided at two positions outside the end face interval of the reinforcing bar. A slit is provided in the direction, and after welding of the reinforcing bar by semi-automatic carbon dioxide welding is completed, a portion outside the slit of the joint sleeve is removed so that a weld inspection by ultrasonic waves can be performed. Item 1 or 2
Reinforcement welding joint method described in 1.