JP7198458B2 - Fixing metal fittings - Google Patents

Description

The present invention relates to reinforcing bars arranged in reinforced concrete structures, such as footings, mat slabs, walls, columns, beams, abutments, bridge piers, tunnels, and the like. The present invention relates to a fixing metal fitting fixed to the tip of a reinforcing bar or the like. In particular, the present invention relates to a fixation metal fitting in which the tip of a reinforcing bar is attached to a through-hole provided in the metal fitting and fixed in a state of being sandwiched between protuberances and bulges formed from the front and rear reinforcing bars of the metal fitting. be.

Conventionally, when constructing a reinforced concrete structure, an anchoring method is used in which the ends of reinforcing bars are bent in an L-shape or a U-shape and embedded in concrete. Moreover, in recent years, a new anchoring construction method has become mainstream, in which anchors are attached to the ends of the reinforcing bars and embedded in concrete without bending the ends of the reinforcing bars.

As an example of the construction method using a fixture, a threaded reinforcing bar is used as the reinforcing bar. A fixing plate with a screw is screwed into it, and the fixing plate with a screw is positioned at a desired position with respect to the screw reinforcing bar. After that, a filling material such as mortar is injected between the screw reinforcing bar and the screwed fixing plate to fix them. In this construction method, it is necessary to use a threaded fixing plate that matches the thickness of the threaded reinforcing bar.In addition, if the thread is damaged during construction, there are many problems that the screwed fixing plate cannot be screwed. .

Further, there has been proposed an apparatus for forming a disk-shaped enlarged diameter portion by hot upsetting the end portion of a reinforcing bar (see, for example, Patent Document 1). This device comprises a heating means for heating the end of a bar such as a reinforcing bar, a clamping device for holding the bar, and a die support block facing the clamping device so as to upset the bar in the clamping device. and a pressing means for moving the heated bar by upsetting the end of the heated bar to form an enlarged diameter portion.

In this device, the heated area of the rebar is compressed to form an enlarged diameter part as a fixing part for fixing to concrete or other rebar, and the fixing plate with holes is formed by hot upsetting. Fixing is also disclosed (Patent Document 1, see FIG. 11). That is, the heated tip of the reinforcing bar is inserted into the hole of the fixing plate and is compressed in the axial direction by the forming surface of the mold, forming enlarged diameter portions of the reinforcing bar on both sides of the fixing plate and fixing them. (See Patent Document 1, paragraphs 0036 to 0037).

However, due to the conditions for heating the ends of the reinforcing bars, the enlarged diameter portions of the reinforcing bars cannot be accurately formed on both sides of the fixing plate. That is, since the hole of the fixing plate is tapered so that the diameter increases on the tip side, the diameter of the tip side of the reinforcing bar greatly expands along the tapered hole of the fixing portion. However, it can be easily imagined that there are cases in which the fixing plate itself rotates relative to the reinforcing bar due to insufficient holding between the taper and the fixing plate due to thermal contraction of the heated reinforcing bar. Needless to say, if the diameter-expanded portion of the reinforcing bar is thin, it will be damaged by the shearing force acting on the reinforcing bar in the axial direction.

Also, it can be easily imagined that the rear end side of the hole in the fixing plate is not a portion that is enlarged in diameter to sufficiently hold the fixing plate compared to the tip portion side of the reinforcing bar. For this reason, it can be easily imagined that there are cases in which the fixing plate moves toward the rear end portion of the reinforcing bar during the method of embedding in concrete or the like.

For this reason, one of the applicants of the present invention has proposed a protruding portion formed by protruding the tip portion of the reinforcing bar from the front of the through hole of the fixing metal fitting and a penetrating portion of the fixing metal fitting, in order to ensure the fixation of the reinforcing bar. A method has been proposed in which the fixing metal fitting is securely sandwiched between the reinforcing bar on the rear side of the hole and the protruding portion that protrudes along the entire circumference (see Patent Document 2). In this proposal, the protuberances and bulges are formed separately by being heated at different times, so that the positions and sizes to be constructed can be made as desired.

Further, preferably, the through-hole of the fixing metal fitting is a through-hole constructed so as to form a "clearance fit" with respect to the reinforcing bar to be fixed. As a result, it is possible not only to insert the reinforcing bar through the through-hole of the fixing bracket, but also to prevent play between them as much as possible. There is also the advantage of being able to be fixed to the reinforcing bar in a stable state even with the fixing metal fittings in the above.

JP-A-2000-288676 JP 2006-194069 A

However, since the bulging portion of Patent Document 2 protrudes from the outermost end surface of the fixing metal fitting, it may be necessary to increase the "covering thickness". That is, the concrete cover thickness from the outermost end surface of the reinforcing bar to the outer surface of the structure is strictly defined. Therefore, for example, when fixing metal fittings are fixed to the tip of a shear reinforcing reinforcing bar of a reinforced concrete structure, not only the fixing metal fittings but also the bulging portion for fixing the fixing metal fittings protrudes beyond the side surface of the main reinforcement. .

Therefore, the thickness of the cover must be measured from the outermost end of the bulging portion to which the fixing metal fitting is fixed. Therefore, the thickness of the bulging portion for fixing the fixing metal fittings as well as the fixing metal fittings fixed to the shear reinforcing reinforcing bars must be added to the thickness of the main reinforcement bundle alone. For this reason, it is desired that the bulging portion to be formed is equivalent to the outermost end surface of the fixing metal fitting and does not protrude significantly from the outermost end surface of the fixing metal fitting. In addition to the shear reinforcing bars, the tips of fixing brackets fixed to other reinforcing bars such as main bars should not protrude significantly from the outermost end surface of the fixing brackets. Needless to say, it is desirable to increase the degree of freedom.

In the present invention, the reinforcing bar is sandwiched between a protruding portion attached to one end of the reinforcing bar and protruding a predetermined portion near the tip of the reinforcing bar and a protruding portion protruding the tip of the reinforcing bar by hot upsetting. To provide a fixing metal fitting that can be formed so that a bulging part does not protrude from the fixing metal fitting or protrudes as little as possible from the fixing metal fitting to be fixed.

The fixing metal fitting according to the invention described in claim 1 is attached to one end of a reinforcing bar to be arranged, and has a raised portion formed by raising a predetermined portion near the tip of the reinforcing bar, and a tip of the reinforcing bar. A fixing metal fitting that is sandwiched and fixed with a bulging portion that is bulged by hot upsetting,
A fixing metal fitting comprising a through hole through which the tip of the reinforcing bar is inserted and a flange formed around the through hole,
More than the opening of the through-hole on the reinforcing-bar insertion side for accommodating a part or all of the hot-upset body at the tip of the reinforcing bar to be accommodated in the inner circumference of the opening of the through-hole on the tip side of the reinforcing bar to be mounted. A pocket part expanded stepwise is formed ,
The corners of the opening of the through-hole on the reinforcing bar insertion side and the stepwise enlarged pocket are chamfered .

In the fixing metal fitting according to the invention described in claim 2, the stepwise enlarged pocket portion according to claim 1 is formed in a circular, elliptical or It is characterized by having a polygonal planar shape.

In the fixing metal fitting according to the invention described in claim 3, the stepwise enlarged pocket portion according to claim 2 is a countersunk enlarged circular hole with respect to the reinforcing bar insertion side opening of the through hole. It is characterized by having a planar shape of

A fixing metal fitting according to the invention recited in claim 4 is characterized in that a planar shape perpendicular to the through hole of the flange portion according to any one of claims 1 to 3 has a teardrop shape. It is.

In the present invention, the reinforcing bar is sandwiched between a protruding portion attached to one end of the reinforcing bar and protruding a predetermined portion near the tip of the reinforcing bar and a protruding portion protruding the tip of the reinforcing bar by hot upsetting. With regard to the fixing metal fitting to be fixed, there is an effect that it is possible to obtain a fixing metal fitting that can be formed so that the protruding portion does not protrude from the fixing metal fitting or protrudes as little as possible from the fixing metal fitting.

1 is an explanatory view showing the configuration of one embodiment of a fixing metal fitting of the present invention; FIG. FIG. 3 is an explanatory view showing an example of a process of fixing the fixing metal fitting shown in FIG. 1 to a reinforcing bar; 1. It is sectional drawing which changed the quantity of the hot upsetting process accommodated in the pocket part of the fixing metal fitting shown in FIG. FIG. 5 is a plan view of another fixing metal fitting of the present invention;

In the present invention, there are provided a protruding portion which is attached to one end of a reinforcing bar to be arranged and is formed by protruding a predetermined portion near the tip of the reinforcing bar, and a bulging portion which is formed by bulging the tip of the reinforcing bar by hot upsetting. The fixing metal fitting is sandwiched and fixed between the projecting portion, and has a through hole through which the tip of the reinforcing bar is inserted, and a flange portion formed around the through hole.

In this fixing metal fitting, the reinforcing bar of the through-hole for accommodating part or all of the hot-upset body of the tip of the reinforcing bar in the inner periphery of the opening of the through-hole on the tip side of the reinforcing bar to be mounted. A pocket portion is formed so as to be enlarged stepwise from the opening on the insertion side. As a result, it is possible to obtain a fixing metal fitting that can be formed so that the bulging portion does not protrude from the outermost end surface of the fixing metal fitting or protrudes as little as possible.

That is, in the present invention, the position of the outermost end of the bulging portion formed by heating the tip of the reinforcing bar and pressing the heated portion in the axial direction of the reinforcing bar is positioned relative to the position of the outermost end surface of the fixing metal fitting. Part or all of the hot upsetting body at the tip of the reinforcing bar is accommodated in the inner periphery of the opening of the through hole on the tip side of the reinforcing bar where the through hole is mounted so that the tip of the reinforcing bar does not protrude or protrudes as little as possible A stepwise enlarged pocket portion is formed from the opening of the through hole on the reinforcing bar insertion side.

Regarding the hot upsetting of reinforcing bars, there are various commercially available manufacturing devices (" DB Head Manufacturing Apparatus", manufactured by DBS Co., Ltd., manufactured by Sanwa Kiko Co., Ltd.) can be used. Four types of manufacturing equipment, manual manufacturing equipment, semi-automatic manufacturing equipment, automatic manufacturing equipment, and high-frequency induction heating manufacturing equipment, have already been sold, and many manufacturing results have been obtained.

The thickness of the fixing metal fitting of the present invention in the through-hole direction may be changed according to the number of reinforcing bars in the concrete to be fixed according to the shaft diameter of the held reinforcing bars. The through-hole of the fixing metal fitting of the present invention may have a size that allows the tip of the reinforcing bar to be loosely fitted therein. In Japan, there are reinforcing bars with a diameter of 10 mm to 51 mm, but depending on the thickness of each reinforcing bar, the diameter of the through-hole of the fixing metal fitting to be used can be changed. .

The flange portion of the fixing metal fitting of the present invention may be formed around the through-hole and may be fixed to concrete. The planar shape orthogonal to the axial center of the reinforcing bars of the collar may be a preferable planar shape depending on the position of the reinforcing bars to be provided. For example, a circular shape, a shape in which a part of a circular arc is cut along a straight line so that a chord appears, or a circular shape in which two opposing arcs are cut in parallel so that a chord appears , a teardrop shape, etc., in which a part of a circular arc protrudes in a “V shape”.

Also, the size of the flange can be changed according to the thickness of the reinforcing bar to be used, the distance from other reinforcing bars to be used, and the like. In particular, for teardrop-shaped ones, variously changed ratios of the elongated portion of the "V-shaped" protrusion to the diameter of the circle are prepared in advance, The optimum one can be selected according to the distance from other reinforcing bars used.

Teardrop shaped ones are very difficult to work with when working with shear reinforcing bars fixed to one end, especially in the case of footings, mat slabs and other intricate grid-like bar arrangements. It is valid. That is, for example, a teardrop-shaped "V-shaped" protruding long part is inserted into the front lattice along the diagonal line of the front lattice-like reinforcement arrangement to extend the rear lattice-like reinforcement arrangement. When it exceeds, the long part of the collar of the teardrop-type anchoring fitting is intersected with the lattice-shaped reinforcing bar at the back by rotating the shearing reinforcing bar to prevent it from coming off.・Arrange them so that they are in contact with each other. By repeating such work, the shear reinforcing bars can be easily arranged, so that the construction procedure can be simplified and the construction schedule can be shortened.

In the hot upsetting process of the present invention, the tip of the reinforcing bar to be fixed is loosely fitted into the through hole of the fixing metal fitting, and then the reinforcing bar and the fixing metal fitting are not moved relative to each other. The front end of the reinforcing bar is heated to soften the reinforcing bar, and the front end of the reinforcing bar is pressed toward the rear end in the axial direction to upset the reinforcing bar. The pressed upsetting body is accommodated in the pocket.

As the stepwise enlarged pocket portion of the present invention, the opening of the through hole on the tip side of the reinforcing bar of the fixing metal fitting is enlarged in a stepped manner around the opening of the through hole on the side where the reinforcing bar is inserted. By pressing, the upsetting body spreads evenly in the pocket around the axis of the reinforcing bar. By arranging the bulging portion (that is, the hot upsetting body) on the stepped bottom surface of the pocket portion on the reinforcing bar insertion side, it is sandwiched and fixed with the protruding portion of the fixing metal fitting on the reinforcing bar insertion side. become a thing.

However, if the thickness of the bulging portion (hot upsetting body) covering the stepped bottom surface is thin, it is weak against the shear force against the force in the axial direction. In order to firmly fix the fixing bracket and the reinforcing bar, the strength must be increased according to the amount of the bulging part (hot upsetting body) covering the stepped bottom of the pocket on the side where the reinforcing bar is inserted. becomes. In addition, when the swaged body reaches the entire inside of the pocket, the swollen part (hot swaged body) in the pocket spreads so as to stretch the inner peripheral wall of the pocket as a whole, and the thickness of the swollen part (hot swaged body) increases. Become. Therefore, in order to firmly fix the fixing metal fitting and the reinforcing bar, firstly, at least the heated portion is pressed in the axial direction of the reinforcing bar, and the position of the widened edge of the bulging portion is arranged stepwise. More preferably, the entire inner peripheral wall of the enlarged pocket is reached.

Therefore, the fixing metal fitting of the present invention is used so that at least the expanded position of the bulging portion (hot upsetting body) reaches the entire inner peripheral wall of the pocket portion. As a matter of course, the fixing strength is improved according to the total amount obtained from the thickness of the widened bulging portion contacting the inner peripheral wall of the pocket portion and the entire inner circumference. In this case, when the heated upsetting body cools down, the upsetting body shrinks, but the upsetting body that expands so as to stretch the inner peripheral wall of the pocket also heats the inner peripheral wall of the pocket. Since the joints are pressed against each other while being pressed against each other, the fixation is well maintained even after cooling.

In order to increase the thickness of the hot swaged body by uniformly spreading the hot swaged body around the axis of the reinforcing bar in the pocket by uniform pressing, the volume of the pocket must be equal to One end of a reinforcing bar having an equivalent volume is heated, the tip of the reinforcing bar is heated to soften the reinforcing bar, and the tip of the reinforcing bar is pressed to the rear end in the axial direction for upsetting. If the thickness of the hot swaged body is increased, not only can a high resistance to the axial shearing force of the reinforcing bar be obtained, but also the hot swaged body faces the inner peripheral wall of the pocket. A tension force and a thermal crimp are obtained at the interface of the upset body and the inner peripheral wall. The tension force and crimping force are generated on the entire inner peripheral wall of the pocket portion with which the widened edge contacts, but are naturally exerted on the entire inner peripheral wall of the through hole.

Regarding the position of the outermost end of the bulging portion (hot upsetting body), the position of the outermost end of the bulging portion is closer to the inner peripheral wall of the pocket than the outer end of the inner peripheral wall of the pocket. Beyond the outer end, it is advantageous in that the thrusting force against the inner peripheral wall of the pocket portion of the upset body is not reduced. This is because, if the position of the outermost end of the bulging portion is the same as the outer end of the inner peripheral wall of the pocket portion, the position of the outermost end of the bulging portion due to thermal contraction of the heated upsetting body will be the same as that of the pocket portion. This is because the thrust force applied to the inner peripheral wall of the pocket portion of the upsetting body is reduced.

However, as described above, for reinforced concrete structures, since the thickness of the concrete cover from the outermost part of the reinforcing bars to the surface is regulated, it is assumed that the bulging part to be formed is equivalent to the fixing metal fittings, and the fixing metal fittings It is desirable not to protrude from the outermost end surface of the For this reason, preferably, the position of the outermost end of the bulging portion is such that the position of the outermost end of the bulging portion of the swaged body before cooling exceeds the outer end of the inner peripheral wall of the pocket portion, and the position of the outermost end of the bulging portion of the upsetting body exceeds the outer end of the inner peripheral wall of the pocket portion after cooling. The position of the outermost end of the bulging portion of the filling body may be the same as the outer end of the inner peripheral wall of the pocket portion.

It should be noted that the position of the outermost end of the swollen part of the swaged body after cooling is not so strict that it should be the same as the outer end of the inner peripheral wall of the pocket part. to some extent, depending on For example, there is a possibility that the length of the diameter of the ties and stirrups attached to the outer circumference of the main reinforcement may be offset against the cover thickness, so the outer end of the inner peripheral wall of the pocket portion may be offset during cooling. It is also effective even when the height is several to several tens of millimeters.

As for the stepwise enlarged pocket portion of the present invention, the through hole for accommodating part or all of the hot upsetting body of the tip portion of the reinforcing bar is accommodated in the inner periphery of the opening of the through hole on the tip side of the reinforcing bar. Anything that is larger than the opening on the reinforcing bar insertion side of the hole may be used. Specifically, the stepwise enlarged pocket portion has a circular, elliptical, or polygonal planar shape that is enlarged with respect to the opening of the through hole on the reinforcing bar insertion side.

In addition, when the stepwise enlarged pocket portion has a circular planar shape that is counterbore-shaped and enlarged with respect to the through hole, the position of the outermost end of the bulging portion is changed by hot upsetting. It becomes easier to evenly reach all the inner peripheral walls of the pocket portion. For this reason, in the conventional fixing metal fixture having a bulging portion formed at the outermost end, the reinforcement work had to be performed in consideration of the thickness of the concrete cover. In addition to being able to be formed so as not to protrude from the fixing bracket or to be as small as possible, a uniform tension force can be obtained on the entire inner peripheral wall of the pocket portion of the upset body, and the strength of fixing to the reinforcing bar is high. Become.

In the fixing metal fitting of the present invention, preferably, the corners of the opening of the through-hole on the reinforcing bar insertion side and the stepwise enlarged pocket are chamfered. As a result, the stress concentration of the shearing force on the bulging portion (hot upsetting body) against the force in the axial direction of the reinforcing bar can be reduced.

Furthermore, when the pocket portion has an elliptical or polygonal planar shape with respect to the through-hole, the position of the widened edge portion of the bulging portion (hot swaged body) is enlarged stepwise. Existence of elliptical long and short diameters of the hot-upgraded body even if a force around the axis is applied to the fixing metal fixture against the fixed reinforcing bar, provided that it reaches the entire inner peripheral wall of the part. Alternatively, the presence of polygonal corners has the effect of mechanically inhibiting rotation. As for the polygonal shape, a pentagon to a dodecagon is preferable in order to ensure good penetration into the corners of the hot swaged body.

As for the manufacturing of the fixing metal fitting of the present invention, it is sufficient that the fixing metal fitting of the present invention is formed with a pocket portion that is enlarged stepwise from the opening of the through hole on the inner periphery of the opening of the through hole on the tip side. Therefore, it can be manufactured by various manufacturing methods. For example, it can be manufactured by various casting methods, forging methods, various composition processing methods, molding such as sintering, removal processing such as cutting, and joining methods for joining a plurality of members. In particular, the casting method, the cold forging method, the hot forging method, the injection molding method, and the like are preferable because of the degree of freedom in the planar shape of the pocket portion. Regarding the casting method, in addition to the degree of freedom of the planar shape, the outside corners of the opening of the above-mentioned through-hole on the side where the reinforcing bars are inserted and the stepped enlarged pocket are naturally chamfered during the casting process. Therefore, it is particularly suitable.

1A and 1B are explanatory diagrams showing the configuration of an embodiment of the fixing metal fitting of the present invention, wherein a is a plan view, b is a side view, c is a cross-sectional view, and d is a cross-section when fixed to a reinforcing bar. Figures and e are plan views showing the state of hot upsetting when fixed to a reinforcing bar. 2A and 2B are explanatory diagrams showing an embodiment of the process of fixing the fixing metal fittings to the reinforcing bars shown in FIG. Fig. c shows the step of pressing the tip of the reinforcing bar to form a bulging portion, Fig. d shows the step of heating the rear end side of the fixing metal fitting, and Fig. e shows the step of forming the raised portion.

3A and 3B are cross-sectional views showing different amounts of hot swaged bodies accommodated in the pocket portion of the fixing metal fitting shown in FIG. The figure is an enlarged cross-sectional view of a state in which the amount of the hot swaged body is reduced, and FIG. c is an enlarged cross-sectional view of a state in which the amount of the hot swaged body is further reduced. FIG. 4 is a plan view of another fixing metal fitting, in which FIG. Fig. c shows a fixing metal fitting having a dodecagonal pocket portion, and Fig. d shows a fixing metal fitting having a circular flange.

As shown in FIGS. 1a to 1c, the fixing metal fitting 10 of this embodiment has a plate-like main body 11, and a through hole 12 for loosely fitting a reinforcing bar extends through the plate-like main body 11 through the front and back sides. formed. A collar portion 13 around the through hole 12 has a teardrop shape in which a part of a circular arc protrudes in a “V shape”, and a teardrop shaped “V shape” protruding portion 14 A chamfered portion 15 is formed on the outer end side of, for example, so that it is easy to operate when inserting a new shear reinforcing reinforcing bar between the reinforcing bars arranged in a grid pattern.

In such a fixing metal fitting, a pocket portion 16 is formed on the outer end side of the through hole 12 so as to be enlarged stepwise from the opening of the through hole 12 on the reinforcing bar insertion side. The stepwise enlarged pocket portion 16 has concentric planes centered on the axis of the through hole 12, and has a substantially vertical countersunk inner peripheral wall 17 half the thickness of the plate-like main body 11. ing. The corner 18 between the opening of the through-hole 12 on the reinforcing bar insertion side and the pocket 16 that is enlarged stepwise has a rounded edge as if it were rounded. This is because the fixing metal fitting of the present embodiment is produced by casting, so that the outer corner portion 18 is rounded.

As shown in FIG. 1d, the fixing metal fitting 10 of this embodiment is attached to one end portion of the reinforcing bar 20 to be arranged, and the portion near the tip of the reinforcing bar 20 immediately behind the fixing metal fitting 10 is raised. It is fixed by being sandwiched between a bulging portion 22 and a bulging portion 21 formed by bulging the tip of the reinforcing bar 20 by hot upsetting.

The protruding portion 21 of the reinforcing bar 20 is pressed in the axial direction from the tip in a state where the tip is heated and softened in advance, so that the bulging portion 21 is swaged into the pocket portion 16 of the fixing metal fitting 10 . The pocket portion 16 of the present embodiment has a circular planar shape that is counterbore-shaped and enlarged with respect to the through hole 12 .

For this reason, as shown in FIG. The heated upsetting body originating from the tip of the reinforcing bar spreads evenly in the pocket portion 16 around the axis of the reinforcing bar to form a bulging portion 21 due to the uniform pressing in the axial direction from the tip of the reinforcing bar. This upsetting body (bulging portion) 21 spreads over the entire circumference of the inner peripheral wall 17 of the pocket portion 16 so as to stretch.

As a result, conventionally, a bulging portion was formed at the outermost end of the fixing metal fitting, and it was necessary to arrange reinforcing bars in consideration of the thickness of the concrete cover. Since part or all of the hot swaged body is accommodated in 16, it is possible to obtain the fixing metal fitting 10 which can be formed so that the bulging portion 21 does not protrude from the fixing metal fitting 10 or protrudes as little as possible. In addition to this, there is an advantage that it is easy to obtain a uniform tension force on all the inner peripheral walls of the pocket portion of the upset body.

An embodiment of the procedure for attaching the fixing metal fitting 10 to the tip of the reinforcing bar is shown in FIG. As shown in FIG. 2a, the tip of the reinforcing bar 20 is loosely fitted into the through hole 12 of the fixing metal fitting 10. As shown in FIG. As shown in FIG. 2b, the tip of the reinforcing bar 20 is heated. In this case, the tip portion of the reinforcing bar 20 indicated by the two-dot chain line is heated, but at that time, the fixing metal fitting 10 is evacuated to the rear end side of the reinforcing bar 20 so as not to be affected by the heat from the heater. You should leave it.

A heater such as a gas heater, a low-frequency induction heater, or a high-frequency induction heater may be used to heat the tip. After being sufficiently heated, the fixing metal fitting 10 is fixed at a predetermined position from the tip of the reinforcing bar, and is pressed from the tip direction to the rear end direction of the axis of the reinforcing bar using a pressurizer, as shown in FIG. 2c. As shown, a swollen portion (hot swaged body) 21 is formed by swaging in the pocket portion 16 of the fixing metal fitting 10 .

The fixing position of the fixing metal fitting 10 is such that the volume of the bulging portion (hot swaged body) 21 accommodated in the pocket portion 16 by pressing becomes larger than the volume covering the entire bottom surface of the pocket portion 16. , the tip portion of the reinforcing bar 20 is positioned at the pocket portion 16 of the fixing metal fitting 10 so that the tip end portion of the bulging portion (hot swaged body) 21 has a volume that does not protrude greatly from the tip surface of the fixing metal fitting 10. It may be fixed at a position that protrudes from the bottom surface.

As shown in FIG. 2d, the reinforcing bar 20 indicated by the two-dot chain line directly below the rear end side of the fixing metal fitting 10 is heated. After being sufficiently heated, a pressurizer is used to press from the front end direction to the rear end direction of the axis of the reinforcing bar to form a raised portion 22 on the rear end side of the fixing metal fitting 10, as shown in FIG. 2e. . As a result, the fixing metal fitting 10 is firmly sandwiched and fixed between the raised portion 22 and the bulging portion (hot swaged body) 21 .

The process shown in FIG. 2 is an example, and for example, which process is first, the process of forming the protuberance 22 or the process of forming the swollen portion (hot swaged body) 21? may be formed at the same time if possible. That is, as described above, the step of forming the swollen portion (hot swaged body) 21 is employed, but the step of forming the swollen portion (hot swaged body) 21 may be performed first. . In this case, the protruding portion 22 may be formed by heating the position where the reinforcing bar protrudes in advance with a heater and pressing the reinforcing bar 20 from the front end direction to the rear end direction of the shaft using a pressurizer.

In addition, if the positions where the bulging portion 21 and the raised portion 22 are to be formed and the amount of heating for each can be predicted in advance, the heating of the bulging portion and the raised portion can be performed simultaneously to operate the pressurizer. The bulging portion 21 and the raised portion 22 may be simultaneously formed by pressing the reinforcing bar 20 from the tip direction toward the rear end direction of the axis thereof.

After confirming that the fixing metal fitting 10 is prevented from moving axially rearward by the protruding portion 22, the fixing metal fitting 10 is removed from the reinforcing bar 20, and the tip side of the reinforcing bar 20 from the protruding portion is heated. The fixing metal fitting 10 is attached to the tip portion of the reinforcing bar 20, and at the position where it is brought into contact with the raised portion 22, the pressurizer is used to press from the tip direction to the rear end direction of the axis of the reinforcing bar 20 to form the bulging portion. (Hot swaged body) 21 is formed.

The amount of the swollen portion (hot swaged body) 21 accommodated in the pocket portion 16 will be described. As for the stepwise enlarged pocket portion 16 of the present embodiment, since the pocket portion 16 of the fixing metal fitting 10 is enlarged stepwise around the through-hole 12 more than the opening diameter of the through-hole 12, The bulging portion (hot upsetting body) 21 spreads evenly in the pocket portion 16 centering on the axis of the reinforcing bar 20 due to the uniform pressing in the direction of the rear end of the axis of the reinforcing bar 20, and the upsetting body 21 spreads so as to stretch the inner peripheral wall 17 of the pocket portion 16 (see FIG. 1e).

Therefore, it is possible to form the bulging portion so as not to protrude from the fixing metal fitting, or to project it as little as possible. If the position of the outermost end of the bulged portion formed by pressing the bulging portion reaches the entire peripheral wall of the pocket portion expanded stepwise, the fixing metal fitting 10 can be fixed by stretching the inner peripheral wall 17 of the pocket portion 16. and the reinforcing bar 20 are firmly fixed.

As shown in FIGS. 3a to 3c, the lengths at which the outermost positions of the bulging portions (hot upsetting bodies) 21, 21b, and 21c contact the inner peripheral wall 17 of the pocket portion 16 are different. ing. In the expanded portion (hot swaged body) 21 shown in FIG. In the expanded portion (hot swaged body) 21b shown in FIG. It has become. The swollen portion (hot upsetting body) 21c shown in FIG. It is positioned at 1/3.

In order to firmly fix the fixing metal fittings and the reinforcing bars with different amounts of the bulging portions (hot upsetting bodies) 21 accommodated in the pocket portions 16, the bulging portions (heat Needless to say, the one shown in FIG. a in which the outermost end of the swaged body 21 exceeds the length of the inner peripheral wall 17 of the pocket portion 16 has the highest strength. This is because the bulging portion (hot swaged body) 21 is thick and can resist the shearing force acting on the reinforcing bar in the axial direction. In addition, if the thickness of the bulging portion (hot upsetting body) 21 is increased, not only can a high resistance force against shearing force in the axial direction of the reinforcing bar be obtained, but also the inner diameter of the upsetting body can be A tension force against the peripheral wall is also obtained.

As the hot upsetting, the front end of the reinforcing bar is heated to soften the reinforcing bar, and the front end of the reinforcing bar is pressed toward the rear end in the axial direction for upsetting. For this reason, the thrusting force that presses the inner peripheral wall of the pocket portion in a direction orthogonal to the surface of the inner peripheral wall by the hot upsetting body made of heated reinforcing bars, and the boundary between the upsetting body and the inner peripheral wall At the surface, thermal crimping is obtained.

Regarding the position of the outermost end of the swollen portion (hot swaged body) 21, the outermost end shown in FIG. Furthermore, the position of the outermost end of the swelling portion (hot swaged body) 21 shown in FIG. If the length exceeds the length of the inner peripheral wall 17 of 16, a higher resistance to the shear force in the axial direction of the reinforcing bar can be obtained. This is because the bulging portion (hot swaged body) 21 is thick.

However, for columns and beams made of reinforced concrete, since the thickness of the concrete covering from the outermost part of the reinforcing bars to the surface is specified, the formed bulging part (hot upsetting body) 21 is used for fixing. It is desired that it is equal to the outermost end of the metal fitting 10 and does not protrude from the outermost end surface of the fixing metal fitting.

For this reason, preferably, the height position of the outermost end of the bulging portion is equal to the length of the inner peripheral wall of the stepped pocket portion where the position of the outermost end of the swaged body (the bulging portion) before it cools down. and the position of the outermost end of the swaged body (bulged portion) during cooling is the same as the length of the inner peripheral wall of the pocket portion. Even if it protrudes slightly beyond the length of the inner peripheral wall of the pocket during cooling, the length of the diameter of the ties and stirrups attached to the outer periphery of the main reinforcement of the column or beam is offset against the cover thickness. It is possible. Therefore, the height position of the outermost end of the bulging portion should be equal to or less than the cancelable projection length.

Further, conventionally, a bulging portion is formed on the outer end surface side of the fixing metal fitting 10, and reinforcement work has to be performed in consideration of the thickness of the concrete cover. Since part or all of the part (hot swaged body) 21 is accommodated, the bulging part (hot swaged body) 21 should not protrude from the fixing metal fitting 10 or should be formed so as not to protrude as much as possible. In addition to that, it is possible to easily obtain a uniform tension force on the entire inner peripheral wall 17 of the pocket portion 16 of the bulging portion (hot swaged body) 21 .

1 to 3, the flange portion 13 around the through-hole 12 penetrating the front and back of the plate-like main body 11 is teardrop-shaped. For example, as shown in FIG. 4, there are others that have similar effects. Specifically, as shown in FIG. 4a, the fixing bracket 30 of another embodiment has a teardrop shape elongated in the longitudinal direction as compared with FIG.

As in FIG. 1, the fixing metal fitting 30 has a teardrop-shaped flange 33 around a through-hole 32 penetrating the front and back of a plate-like main body 31. A chamfered portion 35 is formed on the outer end side of the "V-shaped" protruding portion 34 so as to facilitate operation when inserting new reinforcing bars between the reinforcing bars arranged in a lattice, for example. ing.

A pocket portion 36 is formed on the outer end side of the through hole 32 so as to be enlarged stepwise from the opening of the through hole 32 on the reinforcing bar insertion side. The stepwise enlarged pocket portion 36 has concentric planes centered on the axis of the through hole 32 , and has a substantially vertical countersunk inner peripheral wall 37 half the thickness of the plate-like main body 31 . ing.

The corner 38 between the opening of the through-hole 32 on the reinforcing bar inserting side and the pocket 36 enlarged stepwise has rounded edges as if they were rounded. This is because the fixing metal fitting 30 of the present embodiment is also manufactured by casting, so that the external corners are rounded. In this fixing metal fitting 30 as well, the heated upsetting body derived from the tip of the reinforcing bar spreads evenly in the pocket portion 36 around the axial center of the reinforcing bar to form a bulging portion. This swaged body (expanded portion) spreads over the entire inner circumference of the inner peripheral wall 37 of the pocket portion 36 so as to stretch.

Further, the fixing metal fitting 40 of another embodiment has an elliptical pocket portion 46, as shown in FIG. 4b. As in FIG. 1, the fixing metal fitting 40 has a teardrop-shaped flange 43 around a through-hole 42 penetrating the front and back of a plate-shaped main body 41. A chamfered portion 45 is formed on the outer end side of the "V-shaped" protruding portion 44 so as to facilitate operation when inserting new reinforcing bars between the reinforcing bars arranged in a lattice for molding. ing.

A pocket portion 46 is formed on the outer end side of the through hole 42 so as to be enlarged stepwise from the opening of the through hole 42 on the reinforcing bar insertion side. The stepwise enlarged pocket portion 46 has an elliptical plane formed around the axis of the through hole 42 and has a substantially vertical inner peripheral wall 47 half the thickness of the plate-like main body 41 . .

The corner 48 between the opening of the through-hole 42 on the reinforcing bar inserting side and the pocket 46 enlarged stepwise has rounded edges as if they were rounded. This is because the fixing metal fitting 40 of the present embodiment is also manufactured by casting, so that the external corner portion 48 is rounded. In this fixing metal fitting 40 as well, the heated upsetting body originating from the tip of the reinforcing bar spreads evenly in the pocket portion 46 around the axial center of the reinforcing bar to form a bulging portion.

This upsetting body (expanded portion) spreads over the entire circumference of the inner peripheral wall 47 of the pocket portion 46 so as to stretch. In addition, since the pocket portion is elliptical, even if a force around the axis centering the through hole 42 is applied to the fixing metal fitting 40, the swaged body (bulge portion) extending to the pocket portion 46 is elliptical. Therefore, there is also an effect of mechanically inhibiting rotation.

Further, the fixing metal fitting 50 of another embodiment has a dodecagonal pocket portion as shown in FIG. 4c. As in FIG. 1, the fixing metal fitting 50 has a teardrop-shaped flange 53 around a through-hole 52 penetrating the front and back of a plate-like main body 51. A chamfered portion 55 is formed on the outer end side of the "V-shaped" projecting portion 54 so as to facilitate operation when inserting new reinforcing bars between the reinforcing bars arranged in a lattice for molding. ing.

A pocket portion 56 is formed on the outer end side of the through hole 52 so as to be enlarged stepwise from the opening of the through hole 52 on the reinforcing bar insertion side. The stepwise enlarged pocket portion 56 has a regular dodecagonal plane formed around the axis of the through hole 52, and has a substantially vertical inner peripheral wall 57 half the thickness of the plate-like main body 51. I have.

The corner 58 between the opening of the through-hole 52 on the reinforcing bar inserting side and the pocket 56 enlarged stepwise has a rounded edge as if rounded. This is because the fixing metal fitting of the present embodiment is also manufactured by casting, so that the outer corner portion 58 is rounded. In this fixing metal fitting 50 as well, the heated upsetting body originating from the tip of the reinforcing bar spreads evenly in the pocket portion 56 around the axial center of the reinforcing bar to form a bulging portion.

This swaged body (expanded portion) spreads over the entire circumference of the inner peripheral wall 57 of the pocket portion 56 so as to stretch. In addition, since the pocket portion is a regular dodecagon, even if a force around the axis centering the through hole 52 is applied to the fixing metal fitting 50, the swaged body (bulging portion) that spreads to the pocket portion 56 will not be affected. ) is a regular dodecagon, it also has the effect of mechanically inhibiting rotation.

A fixing metal fitting 60 of another embodiment has a circular collar as shown in FIG. 4d. In this fixing metal fitting 60, a flange portion 63 around a through-hole 62 passing through a plate-like main body 61 from front to back is circular in plane. A pocket portion 66 is formed on the outer end side of the through hole 62 so as to be enlarged stepwise from the opening of the through hole 62 on the reinforcing bar loading side.

The stepwise enlarged pocket portion 66 has concentric planes centered on the axis of the through hole 62 , and has a substantially vertical countersunk inner peripheral wall 67 half the thickness of the plate-like main body 61 . ing. A protruding corner 68 between the opening of the through-hole 62 on the reinforcing bar inserting side and the stepwise enlarged pocket 66 is rounded to round the edge. In this fixing metal fitting 60 as well, the heated upsetting body originating from the tip of the reinforcing bar spreads evenly in the pocket portion 66 around the axial center of the reinforcing bar to form a bulging portion. This swaged body (expanded portion) spreads over the entire circumference of the inner peripheral wall 67 of the pocket portion 66 so as to stretch.

There is no need to use a dedicated threaded reinforcing bar, and even a slight breakage of the reinforcing bar can be sufficiently treated. Since the pocket portion is provided for accommodating a part or all of the fixing metal fitting, the bulging portion protruding outward from the fixing metal fitting can be minimized, which is advantageous in terms of the thickness of the concrete cover.

10, 30, 40, 50, 60... Fixing metal fittings,
11, 31, 41, 51, 61...main body,
12, 32, 42, 52, 62... through holes,
13, 33, 43, 53, 63... brim portion,
14, 34, 44, 54 ... protrusions,
15, 35, 45, 55 ... chamfered portion,
16, 36, 46, 56, 66... pocket portions,
17, 37, 47, 57, 67... inner peripheral wall,
18, 38, 48, 58, 68... Outer corners,
20 ... rebar,
21, 21b, 21c ... swelling portion (hot upsetting body),
22, 22b, 22c ... protuberances,

Claims (4)

A protruding portion attached to one end of a reinforcing bar to be arranged and formed by protruding a predetermined portion near the tip of the reinforcing bar, and a bulging portion formed by bulging the tip of the reinforcing bar by hot upsetting. A fixing metal fitting that is fixed by sandwiching between
A fixing metal fitting comprising a through hole through which the tip of the reinforcing bar is inserted and a flange formed around the through hole,
More than the opening of the through-hole on the reinforcing-bar insertion side for accommodating a part or all of the hot-upset body at the tip of the reinforcing bar to be accommodated in the inner circumference of the opening of the through-hole on the tip side of the reinforcing bar to be mounted. A pocket part expanded stepwise is formed ,
A fixing metal fitting according to claim 1, characterized in that the corners of the opening of the through-hole on the reinforcing bar inserting side and the stepwise enlarged pocket are chamfered . 2. The method according to claim 1, wherein the stepwise enlarged pocket portion has a circular, elliptical, or polygonal planar shape that is enlarged with respect to the opening of the through hole on the reinforcing bar insertion side. Fixing hardware described. 3. The method according to claim 2, wherein the stepwise enlarged pocket portion has a circular planar shape that is counterbore-shaped and enlarged with respect to the opening of the through hole on the reinforcing bar insertion side. Fixing bracket. The fixing metal fitting according to any one of claims 1 to 3 , wherein a planar shape of the flange portion orthogonal to the through hole has a teardrop shape .

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