JP3569507B2 - Reinforcing bar joining method and joining device used for the method - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for joining reinforcing bars and a joining device used for the method.
[0002]
[Prior art]
As shown in FIG. 15, when assembling a reinforced concrete beam by a precast method or a rebar pre-assembly method, a column precast member, a pre-assembled column bar a, and the like are generally erected and fixed in position. For this reason, when the joint of the reinforcing steel c is performed between the precast beam reinforcing bar or the pre-assembled beam reinforcing bar b or the like to be inserted later, in a construction method that requires an upset (pressing accompanied by deformation) like a butt joint by pressure welding, etc. Since the rebar shrinks, it is necessary to move the precast beam reinforcement, the pre-assembled beam reinforcement b, and the like, which is a problem in construction.
[0003]
However, if the joint between the column and the beam is precast, a part of the column and the beam is integrated into a precast member, and the middle of the beam is used as the joint, the above problem does not occur. The weight and volume increase, which hinders transportation and lifting. On the other hand, if you try to precast columns or beams with wire rods, the number of joints by rebar will increase, and the mechanical joining described later will be adopted because deformation and displacement of the wire rods are not allowed, leading to cost increase. I will.
[0004]
For this reason, butt joints by welding or mechanical load transmission, which have no or very little movement of the beam streaks, are used. Not only is it necessary, but also because the construction depends on the weather, and in the latter case, processing of parts and reinforcing bars is required, which is significantly disadvantageous in terms of cost and construction period as compared with the above-mentioned pressure welding method.
[0005]
On the other hand, lap joints such as (1) lap joints caused by adhesion to concrete, (2) lap joints formed by flare welding, and (3) lap joints formed by mechanical load transmission do not require upsets. Problems.
[0006]
[Problems to be solved by the invention]
The lap joints described in the above (1) to (3) are used for wall streaks or slab streaks having a small diameter, but are rarely applied to main bars of columns or beams. This is because in (1), the cross-sectional area of the rebar increases in proportion to the square of the diameter, whereas the circumference in proportion to the adhesive force increases only in a linear relationship with the diameter. This is because, when the diameter increases, the adhesive force sharply decreases relative to the cross-sectional area of the reinforcing bar, which is disadvantageous.
[0007]
(2) is a method in which two joining rebars are overlapped and flare welding is performed using a covered arc welding rod on one or both sides. If the rebar diameter increases, the number of flare welding passes simply increases. Although it is necessary, the workability and the quality of the welded portion are extremely deteriorated depending on the welding posture and the shape of the reinforcing bar.
[0008]
(3), as shown in FIG. 16, the joint hardware e is fitted into the overlapped portion of the two rebars d, and the wedge f is driven between the rebars, and the rebars are joined by crimping. When the rebar diameter increases, the distance between the centers of the two rebars to be joined increases, and a large bending moment is generated. Therefore, the joint metal e needs to be increased in proportion to the square of the diameter. This is because the larger the diameter, the sharper the disadvantage.
[0009]
As related techniques, Japanese Unexamined Patent Publication No. Hei 6-280348 discloses a tubular coupler, a short tubular tapered first joint covering a connecting end of a first reinforcing bar, and a connecting side end of a second reinforcing bar. A short tubular tapered second joint covering the portion, and each joint is formed with an axial cutout in the direction in which the other reinforcing bar extends, and when the rebar is pulled in, the joint is A reinforcing bar lap joint device is shown which is deformed by receiving a side pressure in a notch portion, is crimped to a reinforcing bar, and is integrated. In short, the two rebars are mechanically connected to each other by drawing in the rebar through the joint and the coupler.
[0010]
Japanese Patent Application Laid-Open No. Hei 8-246604 discloses a technique for mechanically reinforcing a superimposed portion of rebars joined in advance, that is, in a lap joint in which ends of rebars are overlapped with each other, clamps are provided on both sides in the overlapping direction. Arrange the metal fittings, fit the grooves of the restraining parts to the ends of each reinforcing bar, insert bolts so as to connect to the through holes of both clamp metal fittings, and tighten them with nuts so that their fulcrum parts abut each other. In this state, a reinforcing bar lap joint reinforcing method is shown in which the restricting portion tightens the ends of the reinforcing bars in the overlapping direction and presses and integrates them in the overlapping state.
[0011]
SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and provides a method of joining a reinforcing bar capable of obtaining a high-quality reinforcing bar joint that does not cause shrinkage at low cost and in a small number of steps, and a joining apparatus used for the method. The purpose is to:
[0012]
[Means for Solving the Problems]
As a first means, in a method in which the ends of two reinforcing bars 1 and 2 are overlapped and joined, a heating step of heating the overlapping portion of the reinforcing bars, and after heating, a radial direction is applied to the overlapping portion of the reinforcing bars. Pressurizing step of applying the above force to join the overlapped portions.
[0013]
As a second means, the method has the first means, and after the contact portion of the reinforcing bar overlapping portion is melted by heating, pressure is applied.
[0014]
As a third means, there is provided the first or second means, and the ends of the two rebars are offset outward from each other by bending, and the insides of the offset portions are brought into contact with each other, so that the overlapping is performed. Form a joint.
[0015]
A fourth means includes the first, second, or third means, and the base ends of the two reinforcing bars are restrained.
[0016]
A fifth means is an apparatus used in the heating / pressurizing step, which has a pair of clamps 3 and 4 which can be freely contacted and separated from each other, and one clamp is used for one of the reinforcing bars forming the overlapping portion. The other clamp has engagement grooves 5 and 6 for engaging the other rebar, respectively, and further heats a superposed portion of the rebar sandwiched between the pair of clamps.
[0017]
The sixth means has a fifth means, and the heating means has a crater 10 capable of injecting a gas flame toward a contact portion of the reinforcing bar in the overlapping portion.
[0018]
As a seventh means, there is provided a fifth means, and the heating means has a power supply device 11 capable of energizing two rebars via the clamp.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
1 to 6 show a method of joining a reinforcing bar according to the present invention.
FIG. 1 shows two rebars 1 and 2 with their tops overlapped, and the base ends of these rebars are restrained by concrete (not shown). Incidentally, it is easier to understand if the reinforcing steel is assumed to be the reinforcing steel c in FIG. In order to join the two rebars, as will be described later, the overlapping portion is heated and then pressed by applying a radial force.
[0020]
The joint strength of the lap joint must be equal to or greater than that of the rebar, and the joint length L 1 of the overlapped portion required to obtain the next joint strength is determined. The strength S of the reinforcing bar is, for example, 175 KN for D25 and SD345, and the breaking strength is about 304 KN.
[0021]
Since the load transmission between the two rebars is caused by shearing, as shown in FIG. 4, if the joining width of the overlapped portion is B, the proof stress S of the joined portion is represented by B × L × 345 ÷ 1.73. You. If B = 10 mm, L = S B ÷ 345 × 1.73 = 175000 ÷ 10 ÷ 345 × 1.73 = 89 mm. Therefore, if the joint length is about 10 cm, a proof stress higher than that of a reinforcing bar can be obtained.
[0022]
The superposed portion of the two rebars superimposed as shown in FIG. 1 with the above-described joint length is first heated. However, upon heating, these rebars are described later so as not to shift in the radial direction. Clamp using device. Heating uses gas flames of acetylene gas and oxygen, electric resistance heat, flash heat, and the like.
[0023]
When a gas flame is used as the heating means, the heating is performed around the contact portion without heating the entire peripheral surfaces of the two rebars. By doing so, the gas consumption and the construction time can be reduced, and the top and the lower part of the reinforcing bar far from the heated part are not heated, so that there is no decrease in rigidity at this part. As described later, a pressing force is applied to the top portion and the lower portion of the reinforcing bar, but stable pressurization is possible because no reduction in rigidity is observed.
[0024]
After heating to the extent that the contact portion of the rebar is melted, pressing force is applied to the top of one rebar and the lower portion of the other rebar to press the two rebars together. The pressure is about 50 MPa as described later. As shown in FIG. 3, the press contact lugs 1a are formed at the contact portions of the reinforcing bars by press contact. This pressure welding hump is an important indicator of the quality of the joint as in normal pressure welding.
[0025]
In addition, as shown in FIG. 5, the two rebars may be linear, respectively. However, as shown in FIG. 6, each end of both rebars is bent to be offset outward from each other. It is also possible to form an overlapping portion by contacting the inside of the offset portion. By doing so, the step 2a is reduced as compared with the case where the reinforcing bars are straight, so that the interference between the reinforcing bars when building the precast concrete is reduced, 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.
[0026]
FIG. 7 to FIG. 10 show an apparatus used for the above-described method of joining reinforcing bars. The device has a fixed clamp 3 and a movable clamp 4, both of which are formed with V-grooves 5, 6 in which the reinforcing bars 1, 2 can be fitted. The groove is not limited to the V-shape but may be a semicircle.
[0027]
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 into the jack. A shaft 8 is slidably inserted into the through hole, and a shaft portion protruding from the through hole further slidably penetrates a through hole formed in the fixed clamp 3, and a tip end thereof is a movable clamp. 4. On the other hand, a reaction force nut 9 is screwed into the base end of the shaft, and is brought into contact with the end surface of the piston rod 7a.
[0028]
A crater 10 capable of injecting a gas flame toward both sides of the contact portion of the overlapping portion 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 needs 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 during upsetting.
[0029]
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 7 a is slightly extended, so that the shaft is By moving the movable clamp 4 closer to the fixed clamp 3 by raising the movable clamp 8, the rebar is gripped by the V groove.
[0030]
Next, a gas flame is injected from the crater 10 to heat and melt the contact portion between the two rebars, and then the piston rod 7a is further extended, so that the rebars are pressurized at a pressure of 50 MPa and joined. FIG. 10 shows the state after pressurization.
[0031]
11 and 14 show a second embodiment of the joining device.
In the present embodiment, the rebar is heated by electric resistance heat or flash heat. That is, by connecting the power supply device 11 to the fixed and movable clamps 3 and 4, both clamps have a function as an electrode in addition to the function as a clamp.
[0032]
At this time, the shaft 8 is coated with an insulating material such as an epoxy resin or a ceramic, and an insulating material 12 is provided between the reaction force nut and the piston rod 7a. Arrange materials. The other configuration is the same as that of the first embodiment, and the description is omitted.
[0033]
Since the operation is the same as described above except for the heating step, only the same step will be described here. When both clamps 3 and 4 are energized by the power supply device 11, the contact portions of the reinforcing bars are melted. Thereafter, both clamps are clamped and pressurized as described above. FIG. 14 shows this state.
In both cases of the first and second embodiments, an example of use of the device in the case where the reinforcing bars are arranged vertically is shown. Use by rotating °.
[0034]
【The invention's effect】
The invention according to claims 1 to 4 only presses the rebar in the radial direction and does not press the rebar in the axial direction, so that no shrinkage occurs at the time of joining the rebar and is equal to or more than a conventional mechanical joint. It is possible to realize the joining quality of the steel sheet with a small number of man-hours and at a low cost, and it is particularly effective for joining a precast beam reinforcement or a pre-assembled beam reinforcement.
[0035]
In addition, since the joint is formed by heating and pressurizing, the joint quality is high, so less wrapping is required to secure the structural performance of the joint than a mechanical lap joint. When doing so, the amount of post-cast concrete can be reduced.
[0036]
Furthermore, even in the joining of deformed reinforcing bars, a special process such as screw processing and a special member such as a filling type sleeve are not required unlike the mechanical lap joint, so that the cost can be further reduced.
[0037]
Furthermore, since the joint can be performed without causing deformation or displacement of the beam member and the amount of post-cast concrete can be reduced, the column and the beam can be precast with a wire, thereby shortening the construction period.
[0038]
Furthermore, since the beam-to-column connection where the number of reinforcing bars becomes the most dense can be precast, labor saving at the site can be achieved.
[0039]
In the invention according to claim 3, since the overlapping portion of the reinforcing bars is offset, the interference between the reinforcing bars at the time of building the precast concrete is reduced, so that the workability can be improved.
[0040]
The invention according to claims 5 to 7 has a pair of clamps, and both clamps have engagement grooves, so that the rebar does not shift during pressurization.
[0041]
Since the invention according to claim 6 has a crater capable of injecting a gas flame toward a contact portion of a reinforcing bar, gas consumption and construction time can be reduced, and the rigidity of the pressurized portion does not decrease. , Stable processing becomes possible.
[Brief description of the drawings]
FIG. 1 is an explanatory view showing a joining method according to the present invention.
FIG. 2 is a schematic diagram showing a bonding state.
FIG. 3 is a cross-sectional view taken along line AA of FIG. 2;
FIG. 4 is an explanatory diagram when a joint length is calculated.
FIG. 5 is a schematic view showing an example of an overlapping portion of a reinforcing bar.
FIG. 6 is a schematic view showing another example of the overlapping portion of the reinforcing bars.
FIG. 7 is a front view of a bonding apparatus used in the above method.
8 is an arrow view as seen from the line BB in FIG. 7;
FIG. 9 is an arrow view as seen from the line CC in FIG. 7;
FIG. 10 is a view similar to FIG. 7, showing a state after pressurization.
FIG. 11 is a view similar to FIG. 7, showing a second embodiment of the bonding apparatus.
FIG. 12 is a diagram corresponding to FIG. 8 of the second embodiment.
FIG. 13 is a diagram corresponding to FIG. 9 of the second embodiment.
FIG. 14 is a view similar to FIG. 10, showing a state after pressurization.
FIG. 15 is a schematic view for explaining a conventional method.
FIG. 16 is an explanatory diagram of a conventional example.
[Explanation of symbols]
1, 2 rebar 3 fixed clamp 4 movable clamp 5, 6 engagement groove 10 crater 11 power supply device

Claims (5)

In the method in which the ends of the two reinforcing bars 1 and 2 are overlapped and joined,
The ends of the two reinforcing bars are offset in the radial direction apart from each other by bending, and the ends are overlapped in a state where the opposing sides of the offset portions are in contact with each other, and the overlapping portion is heated. Process and
A pressure step of applying a force to the overlapping portions of the reinforcing bars after heating to join the overlapping portions. The method for joining rebars according to claim 1, wherein after the contact portion of the rebar overlapping portion is melted by heating, pressure is applied. 2. An apparatus used in the heating / pressing step according to claim 1, comprising a pair of clamps 3 and 4 which can be freely brought into contact with and separated from each other, one of which clamps one of the reinforcing bars forming the overlapping portion. And the other clamp has engagement grooves 5 and 6 for engaging the other rebar, respectively, and further has a heating means for heating the overlapped portion of the rebar sandwiched between the pair of clamps. A joining device used for joining reinforcing bars. The joining apparatus according to claim 3, wherein the heating means has a crater (10) capable of injecting a gas flame toward a contact portion of the reinforcing bar in the overlapping portion. The joining apparatus according to claim 3, wherein the heating means includes a power supply device (11) capable of energizing two rebars via the clamp.

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