JP6035544B2 - Mechanical coupling - Google Patents

Description

  The present invention relates to a mechanical joint for connecting reinforcing bars made of a nonmagnetic metal material.

Conventionally, when building a building, a reinforcing bar is used to reinforce the building. Various joints are used to connect the reinforcing bars.
Currently, mechanical joints that are widely supplied to the market are mainly made of iron from the viewpoints of required strength, material cost, ease of processing during manufacturing, and the like.

  However, since rebars are used in various buildings, the environment in which they are used varies widely. Therefore, for example, in an environment where the influence on the magnetic field is a concern, it is not preferable to use a material mainly composed of a magnetic material such as iron.

  In this regard, Patent Document 1 is a stainless steel rebar joint formed by thermally joining a stainless steel bar base material, containing a solid solution Cr concentration at the interface between the oxide scale and the base metal: 80 to 13.5%, and the balance Has proposed a stainless steel rebar joint made of iron and inevitable impurities.

JP 2010-90456 A

However, at present, no mechanical joint for connecting reinforcing bars made of nonmagnetic metal materials has been provided.
In this regard, the inventors of the present application manufactured a mechanical joint in which a reinforcing bar made of a non-magnetic metal material is connected by a stainless steel sleeve. The reinforcing bar inserted into the through hole of the sleeve It was easy to break in the vicinity of the opening end, and it was not possible to obtain the fatigue strength that the metal used as the material should originally exhibit.

  As a result of investigations by the inventors, the reinforcing bars made of non-magnetic metal material were broken because of the hardness of the metal used as the material of the reinforcing bars and the sleeve and the open end of the through hole of the sleeve. It was found that there was a cause of stress concentration and fine scratches on the nonmagnetic rebar in the vicinity.

  Accordingly, an object of the present invention is to obtain a high mechanical strength by preventing stress concentration on a reinforcing bar in a mechanical joint for connecting reinforcing bars made of a nonmagnetic metal material.

In order to achieve the above object, a mechanical joint according to the present invention is a mechanical joint for connecting reinforcing bars made of nonmagnetic metal, is made of nonmagnetic stainless steel, and has a substantially cylindrical shape into which the reinforcing bars are inserted. The sleeve has a through hole for inserting the reinforcing bar, the end of which is open, and the inner peripheral surface of the opening end of the through hole into which the reinforcing bar is inserted In addition, a tapered surface that gradually increases in diameter toward the opening side is formed.
In the present invention, the term “non-magnetic metal” does not necessarily require strict non-magnetism but also includes a low-magnetic metal. Furthermore, the term “low magnetism” as used herein refers to a magnetism in a range in which magnetism is not preferable, and in the environment where the mechanical joint according to the present invention is used, the influence of magnetism on the environment can be ignored or the influence of magnetism is allowed. means.

  Moreover, the said taper surface is good also as what is formed in R shape toward the opening edge part from the back of the said penetration hole.

  The sleeve may have an uneven thickness at the opening end of the through hole.

  In addition, the sleeve may be subjected to a softening process on an opening end portion of the insertion hole.

  The stainless steel may be austenitic stainless steel.

  According to the present invention, stress concentration in the vicinity of the opening end portion of the through hole of the sleeve can be prevented, and high mechanical strength can be obtained.

In the mechanical coupling which concerns on embodiment of this invention, it is a partial cross section figure which shows the state before a reinforcing bar is connected. In the mechanical coupling which concerns on this embodiment, it is a partial cross section figure which shows the state with which the reinforcing bar was connected. It is a figure which shows the sleeve which comprises the mechanical coupling which concerns on this embodiment, Comprising: It is (a) perspective view, (b) top view, (c) sectional drawing. It is a figure which shows the sleeve which comprises the mechanical coupling which concerns on another embodiment of this invention, Comprising: (a) Perspective view, (b) Top view, (c) AA sectional drawing, (d) BB It is sectional drawing. It is a figure which shows the sleeve which comprises the mechanical coupling which concerns on another embodiment of this invention, Comprising: (a) Perspective view, (b) Top view, (c) AA sectional drawing, (d) BB It is sectional drawing. It is a figure which shows the sleeve which comprises the mechanical coupling which concerns on another embodiment of this invention, Comprising: (a) Perspective view, (b) Top view, (c) AA sectional drawing, (d) BB It is sectional drawing.

Next, an embodiment of the present invention will be described with reference to the drawings.
As shown in FIGS. 1 and 2, the mechanical joint of nonmagnetic reinforcing bars according to the present embodiment includes a cylindrical sleeve 1 and a bolt 2.

As shown in FIG. 3, the sleeve 1 has a substantially cylindrical shape, and includes a reinforcing bar insertion portion 11 constituting one end side and a bolt screwing portion 12 constituting the other end side.
Moreover, the sleeve 1 has the penetration hole 1a in which both ends are opened and a reinforcing bar is inserted from the opening on one end side.
The through hole 1 a of the sleeve 1 includes a reinforcing bar insertion hole 11 a formed in the reinforcing bar insertion part 11 and a bolt screwing hole 12 a formed in the bolt screwing part 12.

The reinforcing bar insertion hole 11a formed in the reinforcing bar insertion part 11 has a smooth inner peripheral surface, has substantially the same diameter as the diameter of the reinforcing bar 3, and the reinforcing bar 3 is inserted through the opening.
When the reinforcing bar 3 is connected to the reinforcing bar insertion portion 11, plastic working is performed to apply a pressing force radially inward from the outer peripheral surface, whereby the reinforcing bar 3 is pressed against the inner peripheral surface of the sleeve 1.

In addition, the diameter of the inner peripheral surface of the opening end portion of the reinforcing bar insertion hole 11a into which the reinforcing bar 3 is inserted out of the opening end portion of the penetration hole 1a is gradually increased from the back toward the opening side (from inside to outside). A tapered surface 13 is formed.
Further, the tapered surface 13 forms an R-shaped curved surface. Thereby, the tightening with respect to the reinforcing bar 3 inserted into the reinforcing bar insertion hole 11a gradually becomes gentle from the back toward the opening side (inside to outside), and the stress is dispersed.

On the other hand, the bolt screwing part 12 is previously reduced in diameter by plastic working from the same diameter as the reinforcing bar insertion part 11, and the diameter is slightly smaller than that of the reinforcing bar insertion part 11.
On the inner peripheral surface of the bolt screw hole 12a formed in the bolt screw part 12, a female screw is formed. A bolt 2 having a male screw formed on the outer peripheral surface is screwed into the bolt screw hole 12a.

The sleeve 1 having the above shape is made of stainless steel. For example, austenitic nonmagnetic stainless steel such as JIS steel type symbols SUS304, SUS305, and SUS316 is more preferably used.
Here, as described above, the sleeve 1 is subjected to plastic working, but the austenitic stainless steel can generate work-induced martensite by cold forging to exhibit magnetism. In this respect, in this embodiment, the magnetization can be suppressed by performing a heat treatment such as annealing described later.
In the implementation of the present invention, it is preferable to suppress the magnetism of the sleeve 1 as much as possible. When there is a metal material that does not become magnetized by plastic working, the present invention does not depend on the metal material exemplified above. A metal material may be used.

Further, in particular, when the reinforcing bar 3 is made of a metal different from that of the sleeve 1, an anticorrosive material is coated or painted on the inner peripheral surface (inner wall) of the through hole 1a in order to prevent electric corrosion from coming into contact with each other May be.
For example, an epoxy resin, a urethane resin, a silicone resin, a polysulfide resin, a polyester resin, or the like can be used as the anticorrosive material.

The bolt 2 is a columnar member having a male screw formed on the outer peripheral surface.
The bolt 2 is made of the same stainless steel as the sleeve 1.

The outer diameter of the bolt 2 corresponds to the diameter of the bolt screwing hole 12a of the sleeve 1, and the bolt 2 can be screwed into the bolt screwing hole 12a in which a female screw is formed on the inner peripheral surface.
Further, the length of the bolt 2 in the axial direction is about twice the length of the bolt screwing hole 12a, and one end side is screwed into the bolt screwing hole 12a of one sleeve 1 and the other end side is inserted. Are screwed into the bolt screw holes 12a of the other sleeves 1, so that the sleeves 1 into which the reinforcing bars 3 are inserted can be connected to each other.

Note that the reinforcing bars 3 to be connected in the present embodiment are deformed reinforcing bars in which uneven ribs are formed on the outer peripheral surface, and are made of a nonmagnetic metal, but unless otherwise specified, the nonmagnetic bars in the implementation of the present invention. The concept includes low magnetism, and thus the nonmagnetic reinforcing bar 3 includes low magnetism.
Further, the surface of the reinforcing bar 3 is coated with an anticorrosive material in order to prevent electrolytic corrosion due to contact with the insertion hole 1 a of the sleeve 1, similarly to the inner peripheral surface (inner wall) of the insertion hole of the sleeve 1. Or it may be painted.
As the anticorrosion material used here, for example, an epoxy resin, a urethane resin, a silicone resin, a polysulfide resin, a polyester resin, or the like can be used.

A process of connecting the reinforcing bars 3 by the mechanical joint having the above configuration will be described.
First, two sleeves 1 are prepared, and the reinforcing bars 3 are inserted into the reinforcing bar insertion holes 11 a of the respective sleeves 1.
Then, the two sleeves 1 in which the reinforcing bars 3 are inserted into the reinforcing bar insertion holes 11a are arranged so that the opening end portions of the bolt screwing holes 12a face each other, and one end side or the other end of the bolt 2 is inserted into each bolt screwing hole 12a. Screw the sides.

Furthermore, the reinforcing bar insertion part 11 in which the reinforcing bar 3 is inserted into the reinforcing bar insertion hole 11a is pressed radially inward from the outer peripheral surface to perform plastic working. By pressing, the diameter of the reinforcing bar insertion hole 11a is reduced, and the inner peripheral surface of the reinforcing bar insertion hole 11a and the reinforcing bar 3 are pressure-bonded.
As a result, as shown in FIG. 2, the reinforcing bar 3 is crimped to the reinforcing bar insertion hole 11 a of each of the two sleeves 1, and the sleeve 1 is connected by the bolt 2 to connect the two reinforcing bars 3.

  According to the mechanical joint according to the present embodiment, an R-shaped tapered surface 13 that gradually increases in diameter toward the opening side is formed on the inner peripheral surface of the opening end portion of the sleeve 1 into which the reinforcing bar 3 is inserted. Therefore, tightening of the reinforcing bar 3 by the sleeve 1 is gradually slowed from the back toward the opening (inside to outside) at the opening end of the sleeve 1. Therefore, concentration of stress can be prevented, and even when the stress is repeatedly or continuously applied, the rebar 3 is hardly broken and high mechanical strength is realized.

Next, sleeves 4, 5, and 6 used in a mechanical joint according to another embodiment of the present invention will be described with reference to FIGS.
As with the sleeve 1, the sleeves 4, 5, and 6 are all formed with taper surfaces 43, 53, and 63 that gradually increase in diameter toward the opening side on the inner peripheral surface of the opening end. The thickness of the reinforcing bar insertion portions 41, 51, 61 in which the reinforcing bar insertion holes 41a, 51a, 61a are inserted is uneven around the circumference.
The sleeves 4, 5, and 6 have a through hole 41, a bolt screw part 42, and a bolt screw hole that have the same configuration as the through hole 11, the bolt screw part 12, and the bolt screw hole 12 a of the sleeve 1. 42a, a through hole 51, a bolt screwing part 52, a bolt screwing hole 52a, a through hole 61, a bolt screwing part 62, and a bolt screwing hole 62a.
Further, the tapered surfaces 43, 53, 63 are formed in an R shape like the tapered surface 13, and tightening of the reinforcing bars 3 inserted into the reinforcing bar insertion holes 41a, 51a, 61a is performed from the back to the opening side (from the inside). The stress gradually disperses toward the outside.

  In the sleeve 4, the reinforcing bar insertion hole 41 a is formed in a circular cross section in accordance with the outer peripheral shape of the reinforcing bar 3, whereas a part of the circle is notched flat in the outer peripheral part of the reinforcing bar insertion part 41. A notch 44 is formed. The notch 44 is formed in the vicinity of the opening end of the reinforcing bar insertion hole 41a. By the notch 44, the thickness of the reinforcing bar insertion part 41 is not increased in the vicinity of the opening end of the reinforcing bar insertion part 41. It is uniform.

In the sleeve 5, the reinforcing bar insertion hole 51a is formed in an elliptical cross section, whereas the outer peripheral portion of the reinforcing bar insertion part 51 is formed in a circular cross section. Due to the difference in cross-sectional shape, the thickness of the reinforcing bar insertion portion 51 is not uniform around the circumference.
In addition, the ellipse constituting the cross-sectional shape of the reinforcing bar insertion hole 51a has a short diameter slightly larger than the diameter of the circle constituting the cross-sectional shape of the reinforcing bar 3, and the reinforcing bar insertion hole 51a can insert the reinforcing bar 3. It is formed to be able to.

Further, the sleeve 6 is formed such that the reinforcing bar insertion hole 61a is gently expanded from the circular cross section to the quadrangular cross section from the back to the opening side (from the inside to the outside). The outer peripheral portion of 61 is formed in a circular cross section. Due to the difference in cross-sectional shape, the thickness of the reinforcing bar insertion portion 61 is not uniform around the circumference.
The quadrangle constituting the cross-sectional shape of the reinforcing bar insertion hole 61a is a substantially square, and one side thereof is slightly larger than the diameter of the circle constituting the cross-sectional shape of the reinforcing bar 3, and the reinforcing bar insertion hole 61a It is formed so that it can be inserted.

  According to the mechanical joint in which the reinforcing bars are connected by the sleeves 4, 5, 6, the opening of the reinforcing bar insertion portions 41, 51, 61 is provided at the opening ends of the reinforcing bar insertion holes 41 a, 51 a, 61 a into which the reinforcing bars 3 are inserted. Since the thickness of the end portion is uneven around the circumference, the opening end portion of the reinforcing bar insertion hole 41a, 51a, 61a is formed where the rebar 3 is loosely tightened. As a result, concentration of stress can be prevented, breakage of the reinforcing bar 3 can be prevented, and high mechanical strength can be realized.

  The above-described sleeves 4, 5, and 6 are examples of a structure for preventing concentration of stress, and at the opening end portions of the reinforcing bar insertion holes 41a, 51a, and 61a, the meat of the reinforcing bar insertion parts 41, 51, and 61 is provided. As long as the thickness can be unevenly distributed around the circumference, the shape is not necessarily limited to the shape of the opening end.

In the above embodiment, in order to further prevent stress concentration and increase the mechanical strength, the opening ends of the reinforcing bar insertion portions 11, 41, 51, 61 of the sleeves 1, 4, 5, 6 are subjected to heat treatment to be softened. May be.
The opening end softening process is realized by, for example, annealing or heat treatment such as solution heat treatment.

By performing the softening process, the reinforcing bar insertion portions 11, 41, 51, 61 are softened from the back toward the opening end (from the inside to the outside), so that they are inserted into the reinforcing bar insertion portions 11, 41, 51, 61. The force for tightening the rebar 3 is gentle from the back of the rebar insertion parts 11, 41, 51, 61 toward the opening end. Therefore, the concentration of stress on the reinforcing bar 3 can be reduced at the opening ends of the reinforcing bar insertion portions 11, 41, 51, 61, thereby preventing breakage of the reinforcing bar 3 in the vicinity of the opening end. .
Further, by applying heat treatment, the slight magnetism generated when the sleeves 1, 4, 5, 6 are pressure-bonded to the reinforcing bar 3 can be canceled out simultaneously.

  In the mechanical joint according to the present embodiment, the sleeves 1, 4, 5, 6 and the bolt 2 are made of nonmagnetic stainless steel. Otherwise, other nonmagnetic metal materials can be used.

  Further, in the mechanical joint according to the above-described embodiment, the reinforcing bar 3 is connected by the pair of sleeves 1, 4, 5, 6 and the bolt 2. However, for example, openings for inserting the reinforcing bars at both ends are provided. Inserting the end portions of the two reinforcing bars 3 from the openings on one end side or the other end side, respectively, and pressing them from the outer peripheral surface by a cylindrical sleeve having a through hole formed with a portion Thus, the reinforcing bar and the mechanical joint may be pressure-bonded. In this case, an R-shaped tapered surface that gradually increases in diameter from the back toward the opening side is formed at the opening at both ends of the sleeve, the thickness is unevenly distributed around the circumference, or a softening process is performed. Just do it.

DESCRIPTION OF SYMBOLS 1 Sleeve 1a Through hole 11 Reinforcing bar insertion part 11a Reinforcing bar insertion hole 12 Bolt screwing part 12a Bolt screwing hole 13 Tapered surface 2 Bolt 3 Reinforcing bar 4 Sleeve 4a Through hole 41 Reinforcing bar insertion part 41a Reinforcing bar insertion hole 42 Bolt screwing part 42a Bolt screwing hole 43 Tapered surface 44 Notch 5 Sleeve 5a Through hole 51 Reinforcing bar insertion part 51a Reinforcing bar insertion hole 52 Bolt screwing part 52a Bolt screwing hole 53 Taper surface 6 Sleeve 6a Through hole 61 Reinforcing bar insertion part 61a Reinforcing bar Insertion hole 62 Bolt screwing part 62a Bolt screwing hole 63 Tapered surface

Claims (4)

A pair of rebars made of non-magnetic metal is a mechanical joint that is crimped into a substantially cylindrical sleeve made of non-magnetic stainless steel,
In the above sleeve,
The through hole for inserting the above-mentioned rebar with the end opened is formed,
The inner peripheral surface of the opening end portion of the transmembrane insertion hole in which the reinforcing bars are inserted is gradually enlarged in R shape toward the opening side,
The open end of the transmembrane insertion hole, the heat treatment is applied,
A mechanical joint characterized by that. The sleeve has a cutout outer peripheral surface of the opening end of the through hole.
The mechanical joint according to claim 1. The sleeve has an uneven thickness at the opening end of the through hole,
The mechanical joint according to claim 1 . A substantially cylindrical sleeve made of non-magnetic stainless steel, having an opening at the end, an insertion hole for inserting a reinforcing bar, and an inner peripheral surface of the opening end of the insertion hole However, due to the sleeve gradually expanding in an R shape toward the opening side,
A method of forming a mechanical joint in which a pair of reinforcing bars made of non-magnetic metal are connected,
Inserting the pair of reinforcing bars into the sleeve, and pressing the sleeve from the outer peripheral surface to press the pair of reinforcing bars;
  Heat-treating the opening end of the through hole of the sleeve,
A method for forming a mechanical joint.

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