JP4257005B2 - Screw rebar - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a screw rebar.
[0002]
[Prior art]
Generally, a threaded reinforcing bar has a pair of screw forming portions opposed to each other in the radial direction on its peripheral surface, and threads are formed at equal intervals in the axial direction in these screw forming portions. A plurality of screw reinforcing bars are connected in a straight line to constitute a main reinforcing bar of a concrete structure. Generally, a cylindrical coupler nut having an internal thread on the inner periphery is used for a joint for connecting threaded reinforcing bars. The ends of the two threaded reinforcing bars to be connected are respectively screwed to both ends of the coupler nut.
[0003]
On the other hand, in Japanese Patent Laid-Open No. 10-121657, a sleeve joint is used for connecting threaded reinforcing bars. The sleeve joint has a cylindrical shape, and no internal thread is formed on the inner periphery. The ends of the two threaded reinforcing bars to be connected are respectively inserted into both ends of the sleeve joint, and a grout material is filled between the inner peripheral surface of the sleeve joint and the threaded reinforcing bar. The grout material enters between adjacent threads and has a thread and catch. At this time, in a general screw rebar, the interval between the screw threads is narrow, and the grout material entering between them is easily sheared. Therefore, the above publication describes that the thread of the threaded reinforcing bar is removed, for example, every one pitch (one turn of the threaded reinforcing bar) or to the extent that some convex portions remain. As a result, the grout material located between the screw threads remaining at the original height increases the shear strength continuously along the axial direction of the screw rebar, and can keep the thread from being caught. As a result, the connection strength between the screw rebars can be maintained.
[0004]
[Problems to be solved by the invention]
However, in the threaded reinforcing bar described in the above publication, the chipping of the thread extends over 1 pitch. Therefore, when the coupler nut is used for the coupling joint, the screw coupling force with the coupler nut is weakened. The necessary connection strength cannot be obtained.
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a threaded reinforcing bar capable of securing sufficient connection strength even when connected by a coupler nut or a sleeve joint. It is in.
[0005]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the first invention has a pair of screw forming portions opposed to each other in the radial direction on the peripheral surface, and threads are formed at equal intervals in the axial direction on these screw forming portions. In the threaded reinforcing bar, each of the thread threads has a first thread thread part and a second thread thread part lower than the first thread thread part.
[0006]
The second invention is characterized in that, in the first invention, in the two screw threads adjacent in the axial direction, the circumferential positions of the first and second screw threads are opposite to each other. To do.
[0007]
According to a third invention, in the first invention, each of the screw threads has a pair of the first screw thread parts, and the second screw thread part is arranged between the first screw thread parts. It is characterized by.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a screw rebar 10 according to a first embodiment of the present invention. On the peripheral surface of the screw rebar 10, a pair of screw forming portions 11 facing each other in the radial direction and a pair of substantially flat unthreaded portions 12 disposed between the screw forming portions 11 are provided. In the screw forming portion 11, screw threads 13 are formed at an equal pitch P (equal intervals) along the axis L direction.
[0009]
As shown in FIGS. 1 and 2, each screw thread 13 has a first screw thread part 14 and a second screw thread part 15 lower than the first screw thread part 14. (In FIG. 2, the two-dot chain line indicates a thread valley.) The height of the second thread portion 15 is about half that of the first thread portion 14. These first and second thread portions 14 and 15 each occupy about half of the length of the thread 13. In the two screw threads 13 adjacent to each other in the axis L direction, the arrangement positions in the circumferential direction of the first and second screw thread portions 14 and 15 are opposite to each other.
[0010]
The effect | action of the screw rebar 10 comprised as mentioned above is demonstrated.
FIG. 3 shows a connection structure A in which two screw rebars 10 are connected by a coupler nut 20. The coupler nut 20 has a cylindrical shape, and an internal thread 21 is formed on the inner periphery thereof. One screw rebar 10 is screwed to about half of the coupler nut 20, and the other screw rebar 10 is screwed to the remaining part. A lock nut 30 is screwed into each screw rebar 10, and the coupler nut 20 is tightened from both sides by the lock nut 30. As a result, the first screw thread portion 14 of the screw rebar 10 is strongly applied to the screw thread 22 of the female screw 21 with a large catching height. The first thread portions 14 are arranged at two ratios in one pitch P of the screw rebar 10 and are arranged alternately in the circumferential direction of each screw forming portion 11, so that the first nut portions 14 are arranged in the axial direction of the coupler nut 20. Can be hooked evenly and closely spaced in the circumferential direction. Thereby, the connection strength of the connection structure A can be reliably maintained high. Further, the second screw thread portion 15 also strongly hits the screw thread 22 of the female screw 21 with a hooking height about half that of the first screw thread portion 14. Thereby, the connection strength can be kept higher.
[0011]
Next, FIG. 4 shows a connection structure B in which two screw rebars 10 are connected by a sleeve joint 40. The sleeve joint 40 has a cylindrical shape, an annular convex portion 41 is formed on the inner periphery thereof, and no female screw is formed. One threaded reinforcing bar 10 is inserted in about half of the inside of the sleeve joint 40, and the other threaded reinforcing bar 10 is inserted in the remaining part. At both ends of the sleeve joint 40, an annular sealing material 42 is provided between the threaded reinforcing bars 10. In the sleeve joint 40, a grout inlet 43 and an air vent 44 are formed. While air is vented from the air vent 44, between the inner peripheral surface of the sleeve joint 40 and the screw rebar 10 from the grout inlet 43. The grout material 50 is filled.
[0012]
The grout material 50 enters between two adjacent screw threads 13. The penetration part 50a between the screw threads 13 in the grout material 50 is connected to the adjacent penetration part 50a along the axis L direction through a step with the first screw thread part 14 in the second screw thread part 15. Yes. Thereby, the shear strength of the entering portion 50a is increased. In addition, since the first and second thread portions 14 and 15 are alternately arranged, the two entering portions 50a connected to each other effectively exhibit the increased shear strength and the first thread portion. The portion 14 can be hooked, and further, the catch between the entering portion 50a and the first screw thread portion 14 can be formed substantially uniformly in both the circumferential direction and the axis L direction of the connection structure B. Thereby, the connection strength of the connection structure B can be sufficiently ensured.
[0013]
As described above, the screw rebar 10 can ensure a sufficient connection strength regardless of whether it is connected by the coupler nut 20 or the sleeve joint 40, and can be applied to any of the connection structures A and B. it can.
[0014]
FIG. 5 shows a threaded reinforcing bar 10A according to the second embodiment of the present invention. Each screw thread 13 of the screw rebar 10A has a pair of first screw thread parts 14, and a second screw thread part 15 is disposed between the first screw thread parts 14.
[0015]
The present invention is not limited to the above-described embodiment, and various forms can be adopted.
For example, the thread 13 having the first and second thread portions 14 and 15 may be formed at least at the end of the screw rebar 10 inserted into the coupler nut 20 or the sleeve joint 40.
All of the first thread portions 14 may be disposed on one end side in the circumferential direction of the screw forming portion 11, and all of the second thread portions 15 may be disposed on the other end side.
In the first embodiment, the first thread portion 14 may be longer than the second thread portion 15 by, for example, about twice.
In the second embodiment, the circumferential positions of the second thread portions 15 adjacent in the direction of the axis L may be shifted from each other.
In the connection structure A, instead of or in addition to tightening the lock nut 30, a grout material may be injected into the gap between the inner periphery of the coupler nut 20 and the screw rebar 10.
[0016]
【The invention's effect】
As described above, in the first and third inventions, the connection strength can be kept high regardless of whether the threaded reinforcing bars are connected by a coupler nut or a sleeve joint.
In the second invention, the connection strength can be kept higher.
[Brief description of the drawings]
FIG. 1A is a side view of a threaded reinforcing bar according to a first embodiment of the present invention.
(B) It is a top view of the said screw reinforcement.
(C) It is a side view of the back side of the said screw reinforcement.
FIG. 2 is a cross-sectional view taken along line II-II in FIG.
FIG. 3 is a cross-sectional view of a connection structure in which two screw rebars are connected by a coupler nut.
FIG. 4 is a cross-sectional view of a connection structure in which two screw rebars are connected by a sleeve joint.
FIG. 5 is a plan view of a threaded reinforcing bar according to a second embodiment of the present invention.
[Explanation of symbols]
10, 10A Screw Reinforcing Bar 11 Thread Forming Part 13 Thread 14 First Thread Part 15 Second Thread Part L Axis

Claims (3)

In the screw rebar having a pair of screw forming portions opposed to each other in the radial direction on the peripheral surface, and thread formed at equal intervals in the axial direction on these screw forming portions,
Each screw thread has a first thread part and a second thread part that is lower than the first thread part. 2. The screw rebar according to claim 1, wherein in two screw threads adjacent in the axial direction, the circumferential positions of the first and second screw thread portions are opposite to each other. 2. The screw rebar according to claim 1, wherein each of the screw threads has a pair of the first screw thread portions, and the second screw thread portion is disposed between the first screw thread portions. .

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