JP2011001765A - Screw type reinforcement joint and connecting method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a screw type reinforcement joint by which stress transmission of each peripheral part of a threadingly fitted part between a male screw part of a reinforcing bar and a threaded tube is made even, enabling transmission of a larger force.SOLUTION: Facing ends of a pair of reinforcing bars 1 joined to each other are formed into male screw parts 1a having a larger diameter. The threaded tube 2 having a female screw part 2a threadingly fitted by the male screw parts 1a of the pair of the reinforcing bars 1 is arranged. Areas L having the length corresponding to one or more thread ridges of the female screw part 2a from both axial end edges of an outer peripheral surface of the screw tube 2 are formed into tapered parts 2b narrowing toward the fronts.

Description

  The present invention relates to a screw-type reinforcing bar joint used for reinforced concrete and a connection method thereof.

In reinforced concrete, various types of reinforcing bar joints are used in order to make a limited standard length reinforcing bar continuous in the field. As reinforced joints, lap joints and gas pressure welding joints in which reinforcing bars are stacked for a predetermined length are generally used. There is a drawback that the quality is affected.
Therefore, as a special joint, a joint for injecting grout with a reinforcing bar into the sleeve has been developed, and a threaded joint has been proposed. The special joint for injecting grout into the sleeve is preferable in terms of simplification of the bar arrangement structure, and has been put to practical use. However, a curing period of about one day is required for hardening the grout, and the construction period is long. There are drawbacks.

  The screw-type joint has the advantage that the curing period required for the grout-injection type special joint is unnecessary, but has not yet been put into practical use. For example, the one shown in Patent Document 1 has been proposed. In this type of threaded joint, for example, as shown in FIG. 11, the opposing ends of a pair of reinforcing bars 1 connected to each other are formed in a large-diameter male screw portion 1a, and the female screw into which these male screw portions 1a are screwed together. A screw cylinder 2 having a portion 2a is provided. The outer peripheral surface of the screw cylinder 2 has the same diameter over the entire length, and has a circular cross section or a polygonal shape.

JP-A-11-336256

  In the screw-type reinforcing bar joint shown in FIG. 11, the female threaded portion 2 a of the screw cylinder 2 and the male threaded portion 1 a of the reinforcing bar 1 are screwed together over a large number of screw threads (for example, a little less than 10). However, when a tensile load is applied between the reinforcing bars 1 on both sides, the stress is not evenly applied to the entire screwed portion a, but the first portion that is the inlet side of the screw tube 2 in the screwed portion. It was found by stress analysis that a considerably uneven stress concentration occurs in the threaded portion a1 of the peripheral thread. That is, the tensile load of the reinforcing bar 1 is almost received at the thread threaded portion a1 in the first circumference, and the remaining threaded portion a does not contribute much to the transmission of the tensile load. Therefore, when a strong tensile load is applied to the reinforcing bar 1, there is a problem that the tensile strength of the screw tube 2 is insufficient and the strength of the thread of the threaded portion a is insufficient, and it is difficult to ensure reliability. Even if the thickness of the screw cylinder 2 is simply increased, the strength of the threaded portion a cannot be improved, and material is wasted due to the increase in the overall thickness.

  Further, in the screw-type reinforcing bar joint shown in FIG. 11, although the load is uneven, the distribution of the tensile load acting on each part of the screw cylinder 2 in the axial direction increases as it reaches the center in the axial direction of the screw cylinder 2. In the center, all tensile loads acting between the reinforcing bars 1 on both sides act. Therefore, there is a possibility that the tensile strength is insufficient at the center portion of the screw cylinder 2. If the thickness of the entire screw cylinder 2 is increased, the thickness of the portion having a sufficient strength is also increased, so that the steel material is wasted.

An object of the present invention is to provide a screw-type reinforcing bar joint in which stress transmission at each peripheral portion in a screwed portion between a male thread portion of a reinforcing bar and a screw cylinder is made uniform, and a larger force can be transmitted. Another object of the present invention is to solve the lack of strength at the center of the screw cylinder without increasing the amount of steel material used unnecessarily.
Still another object of the present invention is to provide a connection method that is excellent in workability when the threaded reinforcing bar joint of the present invention is constructed.

  In the first threaded reinforcing bar joint of the present invention, the opposing ends of a pair of reinforcing bars connected to each other have a large diameter at which the groove bottom diameter of the thread groove is equal to or greater than the outer diameter of the general portion of the reinforcing bar. A screw cylinder formed on a female screw part in which the male screw part of the pair of reinforcing bars is screwed, and an axial edge of both ends on the outer peripheral surface of the screw cylinder. Accordingly, the taper-shaped portion that tapers the range of the length of one or more threads of the female screw portion. Note that the male screw portions of the pair of reinforcing bars may have the same spiral direction, or may be in opposite directions. Corresponding to both male screw portions, the female screw portion of the screw cylinder has the same spiral direction as a whole, or opposite side portions with respect to the center.

  According to this configuration, when a pulling force acts between the reinforcing bars on both sides, the pulling force is transmitted between the reinforcing bars via the threaded portion between the male screw portion of the reinforcing bar and the female screw portion of the screw cylinder. At this time, the tensile force is not evenly distributed and loaded on each peripheral portion of the screwed portion, but the largest force is applied to the screwed portion of the first thread on the inlet side of the screw cylinder. Acts to cause some stress concentration. However, in the present invention, since the range of the length from the end edge on the outer peripheral surface of the screw cylinder to one or a plurality of threads is a tapered portion that is tapered, elastic deformation is most likely to occur. A portion in the vicinity of the screw cylinder inlet, which is a portion to which a large force acts, is elastically deformed into a diameter-expanded state by the action of a pulling force. For this reason, the tensile force borne by the screwing portion of each circumference after the second round will increase, the stress transmission of each peripheral portion in the screwing portion will be made uniform, and without increasing the thickness of the screw cylinder, A large force can be transmitted. In addition, insufficient strength of the threaded portion of the thread is also eliminated. Since the male thread portion of the reinforcing bar has a larger diameter than the general portion, there is no problem of strength reduction due to the formation of the thread groove.

In the screw-type reinforcing bar joint of the present invention, the central portion in the axial direction of the screw cylinder may be a thick wall portion whose outer diameter surface is enlarged.
As the screw tube reaches the center in the axial direction, the tensile force borne by the threaded portion of each circumference is added. At the center in the axial direction, all the tensile force acts between the reinforcing bars on both sides. It will be. However, if the central part of the screw cylinder is a thick part, there is no problem of insufficient strength at the central part of the screw cylinder, and the thick part is only the central part requiring strength, so the screw cylinder is configured. There is no waste of steel. Unlike the case where the thick part of the screw cylinder is expanded to the outer diameter side and expanded to the inner diameter side, the male threaded part of the reinforcing bar is screwed into the screw cylinder beyond the center to the other end side. It does not become an obstacle. Therefore, the workability is not lowered at the thick portion.

In the second threaded reinforcing bar joint according to the present invention, the opposing ends of a pair of reinforcing bars connected to each other have a large diameter where the groove bottom diameter of the thread groove is equal to or greater than the outer diameter of the general portion of the reinforcing bar. A screw cylinder formed on a female screw part in which the male screw part of the pair of reinforcing bars is screwed together, and the shape of the outer peripheral surface of the screw cylinder is formed at both end portions in the axial direction. The outer diameter of this is a shape that is smaller than the outer diameter of the central portion. In this case, a portion of a certain length from the end of the screw shaft may be tapered or the entire center from the end may be tapered, and the central portion of the screw cylinder in the axial direction may be thickened by the outer diameter surface. It may be a meat part.
When the outer peripheral surface of the screw cylinder is tapered, the stress transmission of each peripheral part in the screwed part is made uniform, as in the first joint structure, and the screw cylinder can be made thicker without increasing the thickness. A large force can be transmitted. In addition, if the central part in the axial direction of the screw cylinder is a thick part with an enlarged outer diameter surface, the lack of strength at the center of the screw cylinder can be resolved without increasing the amount of steel used. it can. When the screw tube is tapered from the end edge to the entire center, both the effect of transmitting a tensile load in a wide range at the screwed portion and insufficient strength at the center of the screw tube can be obtained.

The connecting method of the threaded reinforcing bar joint according to the present invention is a connecting method in the threaded reinforcing bar joint of any one of the above configurations according to the present invention, wherein the male threaded portion of one reinforcing bar is opposite to the screwed side end in the screw cylinder. The process of screwing up to the vicinity of the end of the steel bar, the process of bringing the other reinforcing bar into a substantially abutted state with respect to the one reinforcing bar, and screwing back the screw cylinder into which the one reinforcing bar is screwed into the other reinforcing bar. Process.
According to this connection method, since the male threaded portion of one reinforcing bar is screwed into the screw cylinder to the vicinity of the end opposite to the screwed side end, the pair of reinforcing bars to be joined to each other are particularly spaced apart for connection work. The connection can be made by unscrewing the screw tube in the connection completed state without spreading. Therefore, the workability of connection is excellent. Further, the male threaded portion of one of the reinforcing bars may be transported and stored from the factory to the construction site in a state where the male threaded portion is screwed into the screw cylinder to the vicinity of the end opposite to the screwed side end. As a result, the male threaded portion of the reinforcing bar is not exposed by being covered with the screw cylinder, and the male threaded portion is prevented from being damaged by being hit by an instrument or the like during transportation or handling. In addition, said "it is set as a substantially matching state" means making it into a facing state or making it an opposing state through some gaps.

  In the first threaded reinforcing bar joint of the present invention, the opposing ends of a pair of reinforcing bars connected to each other have a large diameter at which the groove bottom diameter of the thread groove is equal to or greater than the outer diameter of the general portion of the reinforcing bar. A screw cylinder formed on a female screw part in which the male screw part of the pair of reinforcing bars is screwed, and an axial edge of both ends on the outer peripheral surface of the screw cylinder. From the above, since the taper portion having a taper is formed in the range of the length of one or a plurality of threads of the female thread portion, the stress transmission of each peripheral portion in the threaded portion between the male thread portion of the reinforcing bar and the screw cylinder is achieved. It is made uniform and a larger force can be transmitted.

In the second threaded reinforcing bar joint of the present invention, the opposing ends of the pair of reinforcing bars connected to each other have a large diameter where the groove bottom diameter of the thread groove is equal to or greater than the outer diameter of the general portion of the reinforcing bar. A screw cylinder formed on a female screw part in which the male screw part of the pair of reinforcing bars is screwed together, and the shape of the outer peripheral surface of the screw cylinder is formed at both end portions in the axial direction. Because the outer diameter of the core is smaller than the outer diameter of the central part, it is possible to perform highly reliable joining without causing stress concentration at some threaded threaded parts, or wasteful use of steel The effect of eliminating the lack of strength at the center of the screw cylinder can be obtained without increasing.
According to a third threaded reinforcing bar joint of the present invention, the opposing ends of a pair of reinforcing bars connected to each other have a large diameter where the groove bottom diameter of the thread groove is equal to or greater than the outer diameter of the general portion of the reinforcing bar. Provided with a threaded cylinder formed on a female threaded part in which the male threaded part of the pair of reinforcing bars is screwed together, and an outer diameter surface of the axially central part of the threaded cylinder is provided. Since the thickened portion has an enlarged diameter, the effect of eliminating the strength shortage at the center of the screw cylinder, which becomes the portion where the tensile force acts most, is eliminated without increasing the amount of steel material used unnecessarily.

  The connecting method of the threaded reinforcing bar joint according to the present invention is a connecting method in the threaded reinforcing bar joint of any one of the above configurations according to the present invention, wherein the male threaded portion of one reinforcing bar is opposite to the screwed side end in the screw cylinder. The process of screwing up to the vicinity of the end of the steel bar, the process of bringing the other reinforcing bar into a substantially abutted state with respect to the one reinforcing bar, and screwing back the screw cylinder into which the one reinforcing bar is screwed into the other reinforcing bar. Therefore, it is possible to obtain an effect of excellent connection workability.

It is sectional drawing of the screw-type reinforcing bar joint in 1st Embodiment of this invention. It is sectional drawing of the decomposition | disassembly state of the screw-type reinforcement joint. It is explanatory drawing of the connection process of the screw-type rebar joint. It is sectional drawing of the screw-type reinforcing bar joint in other embodiment of this invention. It is sectional drawing of the screw-type rebar joint in other embodiment of this invention. It is sectional drawing of the decomposition | disassembly state of the screw-type reinforcement joint. It is sectional drawing of the screw-type rebar joint in other embodiment of this invention. FIG. 8A is a cross-sectional view taken along the line VIII-VIII in FIG. 7, and FIG. 8B is a cross-sectional view of a modified example of the screw cylinder shown in the same cross section. It is sectional drawing of the screw-type rebar joint in other embodiment of this invention. It is sectional drawing of the screw-type rebar joint in other embodiment of this invention. It is sectional drawing of the proposal example of a screw-type screw-type reinforcing steel joint.

  A first embodiment of the present invention will be described with reference to FIGS. In this threaded reinforcing bar joint, opposing ends of a pair of reinforcing bars 1 and 1 connected to each other are formed in a large-diameter male threaded portion 1a, and an inner peripheral surface is a male threaded part 1a of the pair of reinforcing bars 1 and 1, A screw cylinder 2 is provided as a female screw portion 2a to which 1a is screwed. A range L of a length extending from one end of the threaded portion of the female threaded portion 2a to a plurality of peaks on the outer peripheral surface of the screw cylinder 2 from the axial end edges is defined as a tapered portion 2b that is tapered. The cross-sectional shapes of the thread groove and the thread thread of the male thread part 1a and the female thread part 2 are triangular in the illustrated example, but may be trapezoidal or rectangular. In this embodiment, the spiral directions of the male screw portions 1 a and 1 a of both the reinforcing bars 1 and 1 are the same, and the spiral direction of the female screw portion 2 a is the same over the entire length of the screw cylinder 2. Both are forward screw directions.

  The external thread portion 1a of the reinforcing bar 1 has a groove bottom diameter equal to or larger than the outer diameter d1 of the general portion of the reinforcing bar 1. The reinforcing bar 1 may be a deformed reinforcing bar having projecting portions such as a semicircular ridge 1b and an axial ridge 1c as shown in FIG. In that case, the male screw portion 1a may have a groove bottom diameter equal to or greater than the outer diameter d1 of the portion of the reinforcing bar 1 excluding the protrusions 1b and 1c, but as shown in the example of FIG. It is preferable to be equal to or greater than the outer diameter including 1b and 1c.

  The pitch circle diameter d2 (= 2r) of the external thread 1a of the reinforcing bar 1 is preferably increased within a range where no other bearing is generated. This is due to the following reason. The overall thread groove length of the male screw portion 1a is [2πr × (l / P1)] where l is the axial length of the male screw portion 1a and P1 is the lead. Since the ability to transmit the screw force depends on the thread groove length, the axial length l of the male thread portion 1a is greatly increased by increasing the pitch circle diameter d2 (= 2r) to obtain the same thread groove length. Becomes shorter. In addition, when the pitch circle diameter d2 is increased, the male thread 1a can be formed into a deep groove, which also has the ability to transmit screw force. If the axial length 1 of the male screw portion 1a is shortened, the length of the screw cylinder 2 can be shortened, and interference with the surrounding bar arrangement of the reinforcing bar 1 can be avoided. For example, when the reinforcing bar 1 is a main bar of a beam or a column, there are many arrangements of stirrups or hoops around it, but the external thread 1a and the screw cylinder 2 interfere with such arrangements. This is easily avoided.

  For example, the following two types of methods can be employed as a method of providing the reinforcing bar 1 with such a large-diameter male screw portion 1a. One of them is to form a large-diameter portion by applying a compression force to the end of the reinforcing bar 1 while performing high-frequency induction heating, and by threading the large-diameter portion, the large-diameter male screw portion 1a It is a method to do. The other is a method in which a male screw member 1a having a large diameter is formed by joining a male screw member having a diameter larger than that of the reinforcing bar 1 to the end surface of the reinforcing bar 1 by pressure welding or the like.

  The screw cylinder 2 is formed by threading a female thread portion 2a that is uniform over the entire length on the inner peripheral surface of a steel sleeve. The sleeve (not shown) that is the material of the screw cylinder 2 is obtained by cutting a thick steel pipe every length of the screw cylinder, or applying a compressive force to a general thick steel pipe. The thickness may be increased by induction heating to increase the thickness, and the increased thickness steel pipe may be cut off. The tapered portions 2b at both ends of the screw cylinder 2 may be formed by cutting, or may be formed in a tapered shape in the process of increasing the thickness when the above-described thickened steel pipe is used.

  The entire length of the screw cylinder 2 is such that the ends of the male screw parts 1a coincide with the ends of the screw cylinder 2 in a state where the male screw parts 1a of the reinforcing bars 1 and 2 on both sides are screwed together. The length is such that the unthreaded portion of about one round is left on the opening edge of the female screw portion 2a. In the illustrated example, an unthreaded portion of about one turn is left behind. The length of the screw cylinder 2 may be sufficiently longer than the length obtained by adding the lengths of the male screw portions 1a of the reinforcing bars 1 on both sides. In that case, the male threaded portions 1a of the reinforcing bars 1 on both sides are screwed to both ends of the screw cylinder 2, and the interval between the opposing male threaded portions 1a is widened.

  The length range L of the tapered portion 2a to be tapered is preferably as long as possible, and may be up to the center in the axial direction of the screw cylinder 2, but a tool for rotating the screw cylinder 2 at the time of connection work is provided at the center. As the engaging portion, it is preferable to leave a straight tube portion in the center. Moreover, if the taper-shaped part 2a becomes long, it will take time and effort to process the taper-shaped part 2a. Therefore, the length range L of the tapered portion 2a is preferably about 3/4 of the length from one end of the screw cylinder 2 to the center. Considering the labor of the above processing, it may be shortened to some extent as long as the effect of equalizing stress transmission described later by the formation of the tapered portion 2a can be obtained. Therefore, the range L may be about one or two threads of the female thread portion 2a (that is, about one or two leads of the screw lead) or may be more than that. When the unthreaded portion of the male thread portion 1a is generated at the end of the screw cylinder 2, the range L is set to the above-described one or two threads in addition to the length of the unthreaded portion. The number of threads of the female screw portion 2a is, for example, about 7 to 8 threads for each one side portion from the center to the edge. This is a case where the male screw portions 1a, 1a on both sides are substantially abutted as in the example of the figure, and when a wide space is provided between the male screw portions 1a, 1a on both sides, the screw thread to which the space is added is added. It is a number.

  The amount of restriction of the outer diameter by the tapered portion 2b of the screw cylinder 2 (that is, the difference in radius between the minimum diameter portion and the maximum diameter portion of the tapered portion 2b) b is, for example, 1 with respect to the wall thickness t of the screw cylinder 2. It is preferable to set it to about / 2 to 1/5, and about 1/3 is the most preferable. The wall thickness t of the screw cylinder 2 indicates the wall thickness in a cross-sectional shape giving an effective cross-sectional area since the female screw portion 2a is formed.

  According to the joint structure of the reinforcing bar having this configuration, when a tensile force acts between the reinforcing bars 1 on both sides, both the reinforcing bars 1 are connected via the threaded portion a between the male threaded portion 1a of the reinforcing bar 1 and the female threaded portion 2a of the screw cylinder 2. A pulling force is transmitted between them. At this time, the tensile force is not evenly distributed and loaded on each of the peripheral portions a1 to an of the screwing portion a, but the screwing portion of the first screw thread on the inlet side of the screw cylinder. The greatest force acts on a1, and some stress concentration occurs. However, in this embodiment, since both ends of the outer peripheral surface of the screw tube 2 are tapered portions 2a that are tapered, elastic deformation is likely to occur, and the portion near the screw tube inlet that is the portion where the greatest force acts is formed. Then, it is elastically deformed into an expanded state by the action of a pulling force. For this reason, the stress transmission in the screwed portions a2 to an of each circumference after the second round is made uniform, and a larger force can be transmitted without increasing the thickness of the screw cylinder 2. Further, the insufficient strength of the threaded portion a of the screw thread is also eliminated.

  The length range L of the tapered portion 2a to be tapered is preferably as long as possible from the viewpoint of uniform stress transmission. However, as described above, as the engaging portion of the tool for rotating the screw cylinder 2 during the connection work, In addition, it is preferable to leave a straight tube portion in the center, and from the viewpoint of labor of processing the tapered portion 2a, a shorter one is preferable. Therefore, the range L is preferably about 3/4 of the length from one to two threads of the female screw portion 2a to one end of the screw cylinder 2 to the center. When the length range L of the tapered portion 2b is less than one thread, the effect that the tapered portion 2a is easily deformed and stress concentration is relaxed is insufficient.

Since the male thread portion 1a of the reinforcing bar 1 has a large diameter with respect to the general portion, there is no problem of strength reduction due to the formation of the thread groove.
The pair of reinforcing bars 1 connected by the screw cylinder 2 may abut end surfaces of the male screw portions 1a with each other or may not contact each other. However, when they are abutted, the compressive force is directly transmitted between the reinforcing bars 1 and 1. . In reinforced concrete, the reinforcing bar mainly serves as a member that bears the tension, and therefore, the transmission of the compressive force is unlikely to cause a problem in strength in the screw-type reinforcing bar joint.

  FIG. 3 shows an example of a joining method in the joint structure of the reinforcing bars. In this joining method, as shown in FIG. 2A, the male threaded portion 1a of one reinforcing bar 1 (the left reinforcing bar in the same figure) is placed in the screw cylinder 2 in the vicinity of the end opposite to the screwed side end. A process in which the other rebar 2 (the rebar 1 on the right in the figure) is brought into a substantially abutted state (the state in FIG. 5B), and the one rebar 1 is A process of unscrewing the screwed cylinder 2 and screwing it into the other reinforcing bar 1 as shown in FIG. 1 so that the screw cylinder 2 is screwed into the male threaded portions 1a of the reinforcing bars 1 on both sides substantially evenly. Including. In this case, the above-mentioned one reinforcing bar 1 is screwed into the screw cylinder 2 as shown in FIG. 3 (A), transported from the manufacturing factory of this reinforcing bar structure to the construction site of the reinforced concrete, It is preferable to arrange the reinforcing bars 1 in a state in which the screw cylinder 2 is screwed by storing or the like. In addition, the above-mentioned “substantially abutting state (state of FIG. 5B)” means that the state is a butting state or a facing state with a slight gap.

  According to this connection method, since the male threaded portion 1a of one reinforcing bar 1 is screwed into the screw cylinder 2 to the vicinity of the end opposite to the screwed side end, a pair of reinforcing bars to be joined to each other are used for connecting work. Connection can be performed by unscrewing the screw cylinder 2 in an arrangement in a connection completed state without widening the interval. Further, since the male threaded portions 1a and 1a of the reinforcing bars 1 and 1 on both sides are both forward threads, a large force is not required for fastening as compared with the case where one of them will be described later with reference to FIGS. Can be connected. Therefore, the workability of connection is excellent. Further, the male threaded portion 1a of one of the reinforcing bars 1 can be transported and stored from the factory to the construction site with the screw cylinder 2 covered, so that the male threaded portion 1a of the reinforcing bar 1 is damaged by hitting an object during transportation or handling. It is prevented.

  5 and 6 show a joint structure for reinforcing bars according to still another embodiment of the present invention. In this embodiment, in the embodiment shown in FIGS. 1 to 3, the spiral direction of the external thread 1a of the reinforcing bar on one side (left side of the figure) is opposite to the spiral direction of the external thread part 1a of the reinforcing bar on the other side (right side of the figure). The direction is as a reverse screw. The screw cylinder 2 is provided with female screw portions 2a and 2a whose spiral directions are opposite to each other on both sides with respect to the center in the axial direction. Other configurations are the same as those of the first embodiment shown in FIGS.

  In the case of this embodiment, as a connecting operation, the male threaded portion a of the reinforcing bar 1 is screwed from both sides of the screw cylinder 2, and the reinforcing bars 1, 1 on both sides are pulled into the screw cylinder 2 by the rotation of the screw cylinder 2 and fastened. The male threaded portion 1a of one reinforcing bar 1 as shown in FIG. 3 (A) cannot be screwed into the screw cylinder 2 to the vicinity of the end opposite to the screwed side end. As described above, the reinforcing bars 1 and 1 on both sides are drawn into the screw cylinder 2 and fastened, and since the drawn reinforcing bars 1 and 2 are long, a large force is required for fastening work. However, depending on the application, a rebar joint with such a reverse thread is also practical.

  7 and 8 show a reinforcing bar joint structure according to still another embodiment of the present invention. In this example, in the first embodiment shown in FIGS. 1 to 3, the central portion in the axial direction of the screw cylinder 2 is a thick portion 2 c whose outer diameter surface is enlarged. The cross-sectional shape of the cross section along the axial direction of the thick portion 2c may be a trapezoidal shape as in the illustrated example or an arc shape as in the example of FIG. The cross-sectional shape in the cross section perpendicular to the axial direction of the thick portion 2c may be, for example, a circle as shown in FIG. 8A, a polygon such as an octagon as shown in FIG. Although omitted, a part of a circle may be cut off by a pair of parallel surfaces. In the case of a polygon, it is preferable that the number of corners be an even number, for example, so that a parallel portion is formed at a diametrically opposed portion.

As the screw tube 2 reaches the center in the axial direction, a tensile force borne by the screwed portions a1 to an of each circumference is added. All the pulling force will act. However, in this embodiment, since the central part of the screw cylinder 2 is the thick part 2c, the problem of insufficient strength at the central part of the screw cylinder 2 is solved. Since the thick part 2a is only the central part which requires strength, there is no waste of the steel material constituting the screw cylinder 2. Since the thick portion 2c of the screw cylinder 2 is provided with an enlarged diameter toward the outer diameter side, unlike the case where it is expanded toward the inner diameter side, the male thread portion 1a of the reinforcing bar 1 is placed in the screw cylinder 2 at the other end beyond the center. It does not become an obstacle to screwing to the side. Therefore, the workability is not reduced in the thick portion 2c.
Further, when the thick part 2c is polygonal as in the example of FIG. 8B, or when the parallel surface is formed as described above, the thick part 2c is rotated when the screw cylinder 2 is turned. The contact surface of the tool can be used, and the tightening workability of the screw cylinder 2 is improved.
Other configurations and effects in this embodiment are the same as those in the first embodiment.

  FIG. 9 shows still another embodiment of the present invention. In this embodiment, both ends of the screw cylinder 2 are formed in a cylindrical shape without providing tapered portions 2a at both ends of the screw cylinder 2 in the embodiment of FIG. That is, as for the outer peripheral surface shape of the screw cylinder 2, the central portion in the axial direction is a thick-walled portion 2c whose outer diameter surface is enlarged, while the other portions are cylindrical. Other configurations are the same as those of the embodiment of FIG. Although the cross-sectional shape of the cross section along the axial direction of the thick part 2c is trapezoidal, it may be arcuate as in the example of FIG. Further, the cross-sectional shape in the cross section perpendicular to the axial direction of the thick portion 2c may be a circle as shown in FIG. 8A or an octagon as shown in FIG. 8B, as in the embodiment of FIG. It is good also as polygons, such as etc. Furthermore, it is good also as a shape which cut off a part of circular shape by a pair of parallel surface. In the case of a polygon, it is preferable that the number of corners be an even number, for example, so that a parallel portion is formed at a diametrically opposed portion.

  When the thick portion 2c is provided in the center of the screw cylinder 2 as in this embodiment, as described above with reference to the example of FIG. 7, the screw on which all the tensile forces acting between the reinforcing bars 1 and 1 on both sides act. The problem of insufficient strength at the center of the tube 2 is solved. Since the thick part 2a is only the central part which requires strength, there is no waste of the steel material constituting the screw cylinder 2. Further, when the thick part 2c is polygonal as in the example of FIG. 8B, or when the parallel surface is formed as described above, the thick part 2c is rotated when the screw cylinder 2 is turned. The contact surface of the tool can be used, and the tightening workability of the screw cylinder 2 is improved.

DESCRIPTION OF SYMBOLS 1 ... Rebar 1a ... Male screw part 2 ... Screw cylinder 2a ... Female screw part 2b ... Tapered part 2c ... Thick part a ... Screwing part

Claims (5)

  The opposing ends of a pair of reinforcing bars connected to each other are formed into a large-diameter male screw portion in which the groove bottom diameter of the screw groove is equal to or larger than the outer diameter of the general portion of the reinforcing bar, and the inner peripheral surface is A screw cylinder formed on a female screw part into which the male screw part of the pair of reinforcing bars is screwed is provided, and one or more threads of the female screw part are formed from the axial edges of both ends on the outer peripheral surface of the screw cylinder. A threaded steel rebar joint with a taper-shaped part that spans the mountain.   2. The threaded reinforcing bar joint according to claim 1, wherein a central portion in an axial direction of the screw cylinder is a thick portion with an outer diameter surface enlarged. The opposing ends of a pair of reinforcing bars connected to each other are formed into a large-diameter male screw portion in which the groove bottom diameter of the screw groove is equal to or larger than the outer diameter of the general portion of the reinforcing bar, and the inner peripheral surface is A screw cylinder formed in a female thread part into which the male thread part of the pair of reinforcing bars is screwed is provided, and the outer peripheral surface of the screw cylinder has an outer diameter at both end portions in the axial direction with respect to an outer diameter of the central part. A threaded steel rebar joint with a small diameter.
  The opposing ends of a pair of reinforcing bars connected to each other are formed into a large-diameter male screw portion in which the groove bottom diameter of the screw groove is equal to or larger than the outer diameter of the general portion of the reinforcing bar, and the inner peripheral surface is A screw-type reinforcing bar joint provided with a threaded cylinder formed in a female threaded part in which the male threaded part of the pair of reinforcing bars is screwed and having a central part in the axial direction of the threaded cylinder with a thickened outer diameter surface . It is a connection method in the screw-type reinforcing bar joint according to any one of claims 1 to 4, wherein the male thread part of one reinforcing bar is in the screw tube to the vicinity of the end opposite to the screwed side end. A screw including a process of screwing, a process of bringing the other reinforcing bar into a substantially abutted state with respect to the one reinforcing bar, and a process of unscrewing the screw cylinder into which the one reinforcing bar is screwed and screwing the screw into the other reinforcing bar Type rebar joint connection method.

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