JP2003119897A - Method for joining reinforcing bars and joining device used in the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a joint of reinforcing bars capable of preventing the occurrence of shrinkage by reducing man-hour and cost. SOLUTION: In a method for joining end parts of two reinforcing bars 1, 2 by overlapping them mutually, an overlapping part of the reinforcing bars is heated, then a force in the radial direction is applied to the reinforcing bar overlapping part, and the overlapping parts are joined.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reinforcing bar joining method and a joining apparatus used for the method.

[0002]

2. Description of the Related Art As shown in FIG. 15, when a reinforced concrete beam is assembled by a precast method or a rebar preassembly method, a column precast member, a prefabricated column rebar a, etc. are generally constructed in advance and the position is fixed. Has been done. For this reason,
When reinforcing bar c is jointed with pre-cast beam bar or pre-assembled beam bar b, which will be inserted later, shrinks to the reinforcing bar by the method that requires upset (pressurizing with deformation) such as butt joint by pressure welding. Therefore, it is necessary to move the precast beam reinforcement or the pre-assembled beam reinforcement b, which is a problem in construction.

However, in order to precast the joint between the pillar and the beam, if the pillar and the beam are partially integrated into a precast member and the middle of the beam is used as a joint, the above problem does not occur. This increases the weight and volume of the member, which hinders transportation and lifting. On the other hand, when attempting to precast pillars or beams with wire rods, the number of joints due to reinforcing bars increases, and because mechanical deformation and displacement of the wire rods are not allowed, mechanical joining, which will be described later, is adopted, leading to higher costs. I will end up.

For this reason, a butt joint by welding or a mechanical butt joint by which the amount of movement of the beam stiffener does not occur or the amount of movement of which is extremely small is adopted. Not only a special tool is required, but also the construction depends on the weather, and in the latter case, processing of parts and reinforcing bars is required, which is significantly disadvantageous in cost and construction period as compared with the above pressure welding method.

On the other hand, lap joints such as lap joints by adhesion with concrete, lap joints by flare welding, and lap joints by mechanical load transmission do not require upset, but have the following problems.

[0006]

Although the lap joints described above and above are used for wall rebars and slab rebars having a small diameter, they are rarely applied to the main rebars of columns and beams. In this, the rebar cross-sectional area increases in proportion to the square of the diameter, whereas the circumference, which is proportional to the adhesive force, only increases in proportion to the diameter in a linear relationship. This is because the adhesive force sharply decreases relative to the cross-sectional area of the reinforcing bar, which is disadvantageous.

In the method, two joining reinforcing bars are superposed and flare welding is performed by using a covered arc welding rod on one side or both sides thereof. If the reinforcing bar diameter increases, the number of flare welding passes is simply increased. This is because the workability and the quality of the welded portion are extremely deteriorated depending on the welding posture and the shape of the reinforcing bar.

As shown in FIG. 16, the two reinforcing bars d
The joint metal fitting e is fitted to the overlapping portion of, and the wedge f is driven between both the reinforcing bars, and the both reinforcing bars are pressure-bonded to each other. When the diameter of the reinforcing bars becomes large, the two reinforcing bars to be bonded are joined together. This is because the center-to-center distance becomes large and a large bending moment is generated, so that the size of the joint metal fitting e needs to be increased in proportion to the square of the diameter, and a sharp increase in the diameter results in a disadvantage.

Incidentally, as a related technique, Japanese Patent Laid-Open No. 6-280
Japanese Patent No. 348 discloses a tubular coupler, a short tubular taper first armor covering a connecting side end of a first reinforcing bar, and a short tubular taper first covering a connecting side end of a second reinforcing bar. Two joints are provided, and each joint has an axial notch formed in the extension direction of the other reinforcing bar, and the joint receives the lateral pressure at the notch and is deformed by the retraction of the reinforcing bar. A rebar lap joint device is shown that is crimped to and integrated with the rebar. In short, this is to mechanically connect the two reinforcing bars by pulling in the reinforcing bars via the connector and the coupler.

Further, Japanese Laid-Open Patent Publication No. 8-246604 discloses a technique for mechanically reinforcing the overlapping portions of pre-joined rebars, that is, in a lap joint in which reinforcing bar ends are superposed on each other, the direction of superposition. Place the clamp metal fittings on both sides, fit the groove of the restraint part to the end of each rebar,
Insert the bolts so that they connect to the through holes of both clamp fittings, and tighten them with nuts, so that the restraint part tightens the reinforcing bar ends in the stacking direction while the fulcrum parts are abutted against each other A reinforcing bar lap joint reinforcement method is shown.

The present invention has been made in view of the above problems, and a method for joining reinforcing bars capable of obtaining a high-quality reinforcing bar joint which does not cause shrinkage in a low cost and in a small number of steps, and a joining apparatus used therefor. The purpose is to provide.

[0012]

[Means for Solving the Problems] As a first means, in a method of joining end portions of two reinforcing bars 1 and 2 by superimposing them on each other, a heating step of heating a superimposing section of the reinforcing bars and a heating step after heating. A pressurizing step of applying a force in the radial direction to the reinforcing bar overlapping portion to bond the overlapping portion.

As a second means, the first means is provided, and the contact portion of the reinforcing bar overlapping portion is melted by heating and then pressurized.

As a third means, the first or second means is provided, and the ends of the two reinforcing bars are offset outward by bending, and the insides of the offset portions are brought into contact with each other. To form the overlapping portion.

As a fourth means, the first, second, or third means is provided, and the base ends of the two reinforcing bars are restrained.

As a fifth means, an apparatus used in the heating / pressurizing step, which has a pair of clamps 3 and 4 which can be brought into contact with and separated from each other, and one of the clamps forms the overlapping portion. Of the rebar, and the other clamp has engaging grooves 5 and 6 for engaging the other rebar, respectively.
The overlapping portion of the reinforcing bars sandwiched by the pair of clamps is heated.

As the sixth means, in addition to having the fifth means, the heating means has a crater 10 capable of injecting a gas flame toward the contact portion of the reinforcing bars in the overlapping portion.

As a seventh means, in addition to having the fifth means, the heating means has a power supply device 11 capable of energizing two reinforcing bars through the clamp.

[0019]

1 to 6 show a method of joining reinforcing bars according to the present invention. Fig. 1 shows the tip part overlapped 2
This shows the reinforcing bars 1 and 2 of the book, and the base end portions of these reinforcing bars are constrained by concrete (not shown). Incidentally, if the same reinforcing bar is assumed to be the reinforcing bar c in FIG. 15, it will be easier to understand. To join the two reinforcing bars, as described later, after heating the overlapping portion, a radial force is applied to apply pressure.

The proof strength of the lap joint must be equal to or higher than that of the reinforcing bar, and therefore the joining length L of the lap portion required to obtain the next proof strength will be obtained. The strength S of the reinforcing bar is, for example, 1 for D25 and SD345.
The breaking strength is 75 KN and the breaking strength is about 304 KN.

Since the load transmission of the two reinforcing bars is due to shearing, as shown in FIG. 4, if the joining width of the overlapping portion is B, the yield strength S of the joining portion is B × L × 345 ÷ 1.73. It is represented by. If B = 10 mm, then L = S ÷ B ÷ 345
× 1.73 = 175000 ÷ 10 ÷ 345 × 1.73 =
It will be 89 mm. Therefore, if the joint length is about 10 cm, it is possible to obtain a proof stress higher than that of the reinforcing bar.

First, the overlapping portion of the two reinforcing bars which are superposed as shown in FIG. 1 with the above-mentioned joining length is heated, but during heating, these reinforcing bars do not shift in the radial direction. Clamp using the device described below. For heating, gas flame of acetylene gas and oxygen, resistance heat by electricity, flash heat, or the like is used.

When a gas flame is used as the heating means, the entire peripheral surface of the two reinforcing bars is heated without heating the contact portions. By doing so, it is possible to reduce the gas consumption and the construction time, and since the reinforcing bar top and the lower part far from the heating part are not at high temperature, there is no decrease in rigidity in this part. As will be described later, a pressing force is applied to the top portion and the lower portion of the rebar, but since the rigidity is not reduced, stable pressurization is possible.

After heating to such an extent that the contact portions of the reinforcing bars are melted, a pressing force is applied to the top portion of one reinforcing bar and the lower portion of the other reinforcing bar to press them together. The pressing force is 50 as described later.
It is about MPa. As shown in FIG. 3, the pressure contact forms a pressure contact bump 1a at the contact portion of the reinforcing bar. This crimping bump is an important indicator of joint quality, as is the case with normal crimping.

As shown in FIG. 5, each of the two reinforcing bars may have a straight shape, but as shown in FIG.
It is also possible to bend the respective end portions of both the reinforcing bars to offset them outwardly, and to make the overlapping portions by contacting the insides of these offset portions. By doing so, the step 2a is reduced as compared with the case where the reinforcing bars are straight, so that interference between the reinforcing bars is reduced when constructing the precast concrete, and the workability is improved. The offset L is preferably about the radius of the reinforcing bar, and at the same time, the moment due to the offset generated at the joint can be reduced.

FIGS. 7 to 10 show an apparatus used in the method for joining reinforcing bars. The device has a fixed clamp 3 and a movable clamp 4, and both clamps are formed with V grooves 5 and 6 into which the reinforcing bars 1 and 2 can be fitted. The groove is not limited to the V shape, but may be a semicircular shape.

A hydraulic jack 7 is fixed to the fixed clamp 1, and a through hole is formed in a piston rod 7a which is reciprocally fitted in the jack. The shaft 8 is slidably inserted into the through hole, and the shaft portion projecting from the through hole further slidably penetrates through the through hole formed in the fixed clamp 3, and the tip portion thereof is a movable clamp. Connected to four. On the other hand, a reaction force nut 9 is screwed into the base end portion of the shaft and brought into contact with the end surface of the piston rod 7a.

A crater 10 capable of injecting a gas flame toward both sides of the contact portions of the reinforcing bars 1 and 2 is disposed between the clamps 3 and 4. In this case, the crater can be provided only on one side of the contact portion. The hydraulic jack 7 is required to have a capacity of 50 KN (50 × B × L = 50 × 10 × 100) and a stroke of 20 mm or more so that a pressure of 50 MPa can be applied at the time of upsetting.

Next, the operation of the above device will be described.
When joining the reinforcing bars, first, the overlapping portion of the reinforcing bars is positioned between the V grooves 5 and 6 of the clamps 3 and 4, and then the piston rod 7a is slightly stretched, so that the shaft is inserted through the reaction force nut 9. By raising 8 to bring the movable clamp 4 closer to the fixed clamp 3, the rebar is gripped in the V groove.

Next, a gas flame is jetted from the crater 10 to heat and melt the contact portions of both rebars, and then the piston rod 7a is further extended to make both rebars 50MP.
The pressure is applied with the pressure of a to join. FIG. 10 shows the state after pressurization.

11 and 14 show a second embodiment of the joining device. In the present embodiment, heating of the reinforcing bar is performed by electric resistance heat or flash heat. That is, the power supply device 11
Is connected to the fixed and movable clamps 3 and 4, both clamps have a function as an electrode in addition to a function as a clamp.

At this time, the shaft 8 is coated with an insulating material such as epoxy resin or ceramic, and the insulating material 12 is provided between the reaction force nut and the piston rod 7a to prevent a short circuit between both clamps. Place insulation material in place. The other configurations are similar to those of the first embodiment, and thus the description thereof is omitted.

The operation is similar to the above except for the heating step. Therefore, only the step will be described here. When both the clamps 3 and 4 are energized by the power supply device 11, the contact portion of the reinforcing bar is melted. After that, both clamps are clamped and pressed in the same manner as above. This state is shown in Figure 1.
It is 4. Although both the first and second embodiments show examples of use of the device when the reinforcing bars are arranged vertically, when the reinforcing bars are arranged horizontally, the joining device is Use by rotating it.

[0034]

The invention according to claims 1 to 4 only presses the reinforcing bar in the radial direction and does not pressurize the reinforcing bar in the axial direction. It is possible to achieve joint quality equal to or better than that of the formula joint with a small number of steps and low cost, and it is particularly effective for joining precast beam bars and pre-assembled beam bars.

Further, since the joint portion is formed by heating and pressurizing, the joining quality is high, and therefore the lap margin for securing the structural performance of the joint is smaller than that of the mechanical lap joint, and in particular, the precast The amount of post-cast concrete can be reduced when applied to members.

Further, even in the case of joining deformed rebars, it is possible to further reduce the cost because a special process such as screwing and a special member such as a filling type sleeve are not required unlike the mechanical lap joint.

Furthermore, since the beam members can be joined without causing deformation or displacement and the amount of post-cast concrete can be reduced, the pillars and beams can be precast with wire rods, which shortens the construction period. .

Furthermore, since the column-beam joint portion where the number of reinforcing bars is most dense can be precast, it is possible to save labor on site.

According to the third aspect of the present invention, since the overlapping portions of the reinforcing bars are offset, the interference between the reinforcing bars when constructing the precast concrete is reduced, so that the workability can be improved.

The invention according to claims 5 to 7 has a pair of clamps, and both clamps have an engaging groove, so that the reinforcing bar will not be displaced during pressurization.

The invention according to claim 6 has a crater capable of injecting a gas flame toward the contact portion of the reinforcing bar, so that the consumption of gas and the construction time can be reduced, and the rigidity of the pressurizing portion is lowered. Since it is not, stable processing is possible.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a joining method according to the present invention.

FIG. 2 is likewise a schematic view showing a joined state.

3 is a sectional view taken along the line AA of FIG.

FIG. 4 is likewise an explanatory diagram for obtaining a joining length.

FIG. 5 is a schematic view showing an example of an overlapping portion of reinforcing bars.

FIG. 6 is a schematic view showing another example of the overlapping portion of the reinforcing bars.

FIG. 7 is likewise a front view of the joining device used in the above method.

FIG. 8 is likewise a view seen from the line BB of FIG.

FIG. 9 is likewise a view seen from the line C-C in FIG. 7.

FIG. 10 is also a view corresponding to FIG. 7, showing a state after pressurization.

FIG. 11 is likewise FIG. 7 showing a second embodiment of the joining device.
FIG.

FIG. 12 is also a view corresponding to FIG. 8 of the second embodiment.

FIG. 13 is also a view corresponding to FIG. 9 of the second embodiment.

FIG. 14 is also a view corresponding to FIG. 10 showing a state after pressurization.

FIG. 15 is a schematic diagram for explaining a conventional construction method.

FIG. 16 is likewise an explanatory view of a conventional example.

[Explanation of symbols]

1, 2 rebar 3 fixed clamp 4 movable clamps 5, 6 Engagement groove 10 crater 11 Power supply device

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hideki Furukawa             4-1-1 Honmachi, Chuo-ku, Osaka-shi, Osaka Prefecture             Takenaka Corporation Osaka Main Store F-term (reference) 2E125 AA48 AB11 AC14 AC18 BE10                       CA90                 2E164 AA02 BA24

Claims (7)

[Claims] 1. A method of overlapping and joining ends of two reinforcing bars 1, 2 in a heating step of heating the overlapping portion of the reinforcing bar, and after heating, a radial direction is applied to the overlapping portion of the reinforcing bar. And a step of applying pressure to join the overlapped portions together. 2. The method for joining reinforcing bars according to claim 1, wherein the contact portions of the reinforcing bar overlapping portions are melted by heating and then pressed. 3. The overlapping portion is formed by offsetting the respective end portions of the two reinforcing bars outwards by bending and contacting the inner sides of the offset portions with each other. The method for joining reinforcing bars according to 1 or 2. 4. The method of joining reinforcing bars according to claim 1, 2 or 3, wherein the base ends of the two reinforcing bars are restrained. 5. An apparatus used in the heating / pressurizing step, comprising a pair of clamps 3 and 4 which can be brought into contact with and separated from each other, and one of the clamps is one of the reinforcing bars forming the overlapping portion, The other clamp has engaging grooves 5 and 6 for respectively engaging the other reinforcing bar, and further has heating means for heating the overlapping portion of the reinforcing bars sandwiched by the pair of clamps. A joining device used for joining reinforcing bars. 6. The joining apparatus according to claim 5, wherein the heating means has a crater 10 capable of injecting a gas flame toward a contact portion of a reinforcing bar in the overlapping portion. 7. The heating means is connected to the clamp 2 via the clamp.
The joining device according to claim 5, further comprising a power feeding device 11 capable of energizing the reinforcing bars of the book.