JP3156159B2 - Method and apparatus for bending FRP reinforcement - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method and an apparatus for bending an FRP reinforcing bar used as a reinforcing bar for civil engineering or construction, instead of a reinforcing bar.

[Conventional technology and its problems]

The FRP reinforcing bar is formed of a rod-like body in which a large number of organic synthetic fibers are bundled and bonded together in a radial direction with a thermosetting resin, and can be used instead of a reinforcing bar. This kind of FR
P reinforcement is a thermosetting resin that bonds fibers, so conventionally, in the molding production line of a factory, if it is not in an uncured or semi-cured state, it cannot be bent, As for the shape, only the size determined by the mold or mandrel specified at the time of molding was obtained, and it was extremely difficult to deal with various shapes and sizes.

In addition, this type of FRP reinforcement is required to be bent quickly at the construction site, but even if the resin-cured rod is heated by an external heating method and bent, it will be long. Must be heated for about 30 minutes.

Further, when the rod is heated at a high temperature for a long time by the external heating method, the outer surface of the rod becomes high in temperature, so that the physical properties of the fiber are impaired, and therefore the mechanical properties of the rod, that is, the reinforcing bar are impaired.

Furthermore, when heating and bending this type of FRP rod-shaped body, if the fibers constituting the rod-shaped body do not have specific physical properties, even if heated and bent in a short time, Again, it has been found that the mechanical properties of the rod before bending are reduced.

The present invention has been made in view of the above problems, the FRP rod-shaped body using a thermosetting resin, quickly at the construction site, etc.
Further, it is an object of the present invention to provide a processing method and an apparatus which can be bent and formed into a predetermined shape and can be formed without deteriorating the mechanical properties of the FRP rod.

[Means and actions for solving the problem]

In order to achieve the above object, the bending method of the present invention is based on the premise that the organic synthetic fibers constituting the FRP reinforcement have mechanical properties described later. By sticking the organic synthetic fibers to each other in the radial direction with a thermosetting resin, the rod-shaped body preformed is heated in a predetermined temperature range by high-frequency dielectric heating or microwave heating to soften the thermosetting resin. . Next, the rod-shaped body is bent while the thermosetting resin is softened.

The reinforcing effect of the fiber-reinforced resin using continuous fibers is high, because if the fiber alignment is uniform, it follows the extremely simplified compound rule and is proportional to the tensile strength of the fiber and the adhesive force of the cement. Tensile strength and modulus are required.

Therefore, as the organic synthetic fiber constituting the FRP reinforcement of the present invention, its tensile strength is 15 g per denier.
As described above, the initial elastic modulus needs to be 300 g or more per denier. Preferably, the tensile strength is 17 g per denier
-30 g, and an initial elastic modulus of 450 g-1000 g are preferred. Tensile strength and initial modulus are each 15 g per denier
If it is less than 300 g, the performance as a concrete reinforcing bar cannot be sufficiently exhibited.

Further, the cutting elongation of the organic synthetic fiber needs to be 3.5% or more. When the elongation at break is less than 3.5%, when the rod-shaped body is heated and bent, breakage or buckling of the organic synthetic fiber occurs in the bent portion, and therefore, the mechanical properties of the rod-shaped body are impaired. .

By the way, conventionally, the lower limit of the bending radius of the rod has been determined by the diameter of the rod. In contrast,
The rod-shaped body comprising the thermosetting resin of the present invention and fibers containing polyvinyl alcohol (hereinafter, referred to as “PVA”) synthetic fiber or wholly aromatic polyester synthetic fiber is softened by high-frequency heating or microwave heating. By
The bending process can be performed without being limited to the bending radius as in the case of the reinforcing bar. This is a fact that breaks common sense that had never been thought before.

That is, as the organic synthetic fibers constituting the rod-shaped body, the mechanical properties described above, or after softening by microwave, are limited to the same bending radius as the rebar or the minimum bending radius depending on the diameter of the rod-shaped body. It has been found that PVA-based synthetic fibers or wholly aromatic polyester-based synthetic fibers are suitable in that they can be bent without being subjected to bending.

The PVA-based synthetic fiber used in the present invention has a degree of polymerization of 1000.
Using PVA with a saponification degree of 98 mol% or more at ~ 20,000
It is obtained by using specific conditions in a spinning method such as a wet method, a dry-wet method, and a dry method.
It is produced by the method described in US Pat. Of course, a mixture of a plasticizer, an oil agent and the like may be used.

A wholly aromatic polyester is an aromatic polyester that can be melt-processed by condensation of one or more aromatic hydroxy acids, optionally with aromatic diols and / or aromatic diacids, wherein at least one of the components present is present. A wholly aromatic polyester, which is called wholly aromatic in the sense that one aromatic ring contributes to the polymer main chain, and is a so-called thermotropic liquid crystalline wholly aromatic polyester capable of forming an anisotropic molten phase It is. In the present invention, a fiber which is melt-spun from such a wholly aromatic polyester and further heat-treated at a melting point of the wholly aromatic polyester and at a temperature 50 ° C. lower than the melting point is used as an organic synthetic fiber.

The rod-shaped body of the present invention is characterized in that both fibers are 100%
It is not limited to the one used. For example, when a rod is formed only of glass fiber or carbon fiber, a problem such as breakage occurs during bending of the rod. However, glass fiber or the like is mixed with the PVA-based fiber and / or wholly aromatic polyester fiber of the present invention. Alternatively, the rod-shaped body can be bent by disposing the glass fiber at the core portion of the bundle.

In the rod-shaped body, the volume occupied by the fibers is preferably 60% or more. That is, the volume occupied by the resin is preferably less than 40% by volume. The reason for this is that, as is clear from the rules of compounding, the smaller the amount of the resin that is the matrix, the stronger the fiber exerts its strength as a reinforcing material, and the higher the tensile strength and Young's modulus of the compound (rod-like body). In the present invention, when the volume occupied by the fibers in the rod-shaped body is less than 60%, the mechanical properties such as the strength and Young's modulus of the fibers are inferior.

In addition, in order to manufacture the rod-shaped body itself by the draw molding which is a premise of the present invention, it is preferable to use a large amount of resin. The reason for this is that when the amount of the resin is large, when the fibers pass through the inside of the drawing nozzle, the infiltration of air is suppressed and the fibers are formed smoothly. However, if the amount of the resin exceeds 40% by volume, the resin sagging and bulge at the time of the bending process become thick, and the shape of the rod-shaped body is changed, which is not preferable.

As the thermosetting resin to which the fibers are adhered, those using unsaturated polyester, epoxy resin, water-soluble epoxy resin, vinyl ester resin, melamine-formalin resin, phenol resin, urea resin and the like are preferable. In particular,
Epoxy resins or vinyl ester (epoxy acrylate) resins are more preferable in terms of alkali resistance and handling.

The softening temperature of the rod can be determined by differential thermal analysis. Even in the case where a thermosetting resin is used, the temperature at which the shift to the heat absorbing side starts is the softening temperature, that is, the glass transition temperature, as in the case of the amorphous polymer. The softening temperature of the epoxy resin is 110 ° C. to 140 ° C., which slightly shifts to a high temperature side depending on the thermosetting conditions, but is determined by measuring by the above-described differential thermal analysis method.

According to the present invention, what has conventionally been considered to be impossible to bend unless the resin is a rod in a semi-cured state is now softened by internal heating of a rod which has been molded and cured. In addition, bending can be easily performed without deteriorating physical properties.

If the bending temperature is lower than the softening start temperature of the thermosetting resin, it is difficult to bend and does not easily bend, cracking or buckling occurs, and the strength of the bent portion decreases. If the temperature is higher than 200 ° C., the strength of the organic synthetic fiber itself decreases,
In addition, since the resin is decomposed and the adhesion between the resin and the fiber is impaired, the strength of the rod-shaped body is reduced.

The present inventors have conducted intensive studies on the internal heating method of the FRP rod, and found that the frequency was 10 MHz to 50 MHz, preferably
35MHz ~ 42MHz, its output is 0.5Kw ~ 100Kw, preferably 1K
High frequency dielectric heating of w ~ 7Kw or frequency of 2000MHz
~ 3000MHz, preferably about 2450MHz, its output is 0.5Kw
Microwave heating of ~ 10Kw, preferably 1Kw ~ 3Kw is preferred, and it has been found that according to these internal heating methods, a flexible FRP rod that is sufficiently plasticized to the inside with a heating time of 5 minutes or less can be obtained. . Although it depends on the diameter and cross-sectional shape of the rod, the surface roughness, etc., it is preferably 4 minutes or less,
It was found that it softened by heating for less than a minute.

Normally, when heating with hot air, heat radiation, or the like, a long heating time is required to heat the rod-shaped body to the inside, and it cannot be handled at the construction site. For example, in the case of a rod having a diameter of 3 mm to 50 mm, or a single rod having a large number of single wires bundled together, or a rod having a stranded wire, it takes 50 minutes to heat.
It takes about 100 minutes. Moreover, since the temperature between the surface portion and the inside becomes high, the resin and the fiber on the surface are deteriorated by heating, so that it is difficult to bend and the mechanical properties of the FRP rod-shaped body are extremely lowered, which is not preferable.

In the bending step of the rod-shaped body, it is preferable to bend the rod-shaped body along a mold in a state where the thermosetting resin is softened, and to cool the rod-shaped body along the mold. The reason is that even if the rod is bent into a predetermined shape, if the temperature of the rod is high, the shape of the rod is not stable, it is difficult to handle, and the rod cannot be used. Therefore, by cooling the heated rod-like body in a state of being bent along the mold, a rod-like body of a predetermined shape can be quickly obtained.

As described above, according to the present invention, the working becomes easy and quick, and the mechanical properties of the rod-shaped body can be maintained.

 Next, the bending apparatus will be described.

The bending apparatus according to the present invention includes a high-frequency dielectric heating device or a microwave heating device for heating a rod-like body, and a molding apparatus for molding the heated rod-like body into a predetermined shape. The molding apparatus includes a fixed mold and a movable mold, and a cooling water passage for flowing cooling water is formed in each mold. The fixed die is fixed to a base, and the fixed die is provided along the inside of the rod-shaped body having a small radius of curvature of the bent portion.
The movable mold is slidably attached to the base and presses the outside of the rod-shaped body having a large radius of curvature of the bent portion.

Since the rod is cooled while being pressed between the two molds, a rod having a predetermined shape can be quickly obtained as described above.

〔Example〕

Hereinafter, an embodiment of a bending apparatus according to the present invention will be described with reference to the drawings.

The bending apparatus includes the high-frequency heating device 10 shown in FIG. 1 or the microwave heating device 20 shown in FIG. 3, and the molding device 30 shown in FIG. 4 or FIG. The heating devices 10 and 20 shown in FIG. 1 or FIG. 3 internally heat a rod-shaped body 50 formed by bonding bundles of fibers containing organic synthetic fibers to each other with a thermosetting resin in a radial direction. The molding apparatus 30 shown in FIG. 4 or 7 is for molding the heated rod 50 into a predetermined shape.

 First, the high-frequency heating device 10 shown in FIG. 1 will be described.

Reference numeral 11 denotes terminals of the high-frequency oscillator, which are arranged in a large number in the length direction of the rod-shaped body 50. Terminal 11 of each high-frequency oscillator is ON / OF
The switch 12 is connected to the high-frequency oscillator 13 via the F switch 12, and the number of switches 12 corresponding to the heating length of the rod 50 is
By setting the ON state, the heating length of the rod 50 is adjusted. The high-frequency oscillator 13 is supplied with 5 KVA of power from, for example, a 200 V power supply (not shown).

The terminal 11 of the high-frequency oscillator is attached to the fixed heating plate 14 or the movable heating plate 15. As shown in FIG. 2, the movable heating plate 15 can move in the radial direction R of the rod-shaped body 50, and the input by the stepping moves in the radial direction R via a link mechanism (not shown), so that the movable heating plate 15 has various shapes and dimensions. To be in pressure contact with the rod-shaped body 50. The rod 50 is inserted between the pair of heating plates 14 and 15 from the direction of arrow A.

In FIG. 1, a temperature sensor 16 is attached to a terminal 11 of the high-frequency oscillator. The temperature sensor 16 is in contact with the surface of the rod 50, measures the temperature of the surface of the rod 50, and outputs a temperature signal c to the controller 17. Controller 17
Is to output a control signal d for stopping the power supply from the power supply to the high-frequency oscillator 13 when the heating temperature of the rod reaches the set temperature.

Although FIG. 2 shows a round bar-shaped rod 50, it goes without saying that the rod 50 can be heated even if it is rectangular.

This high-frequency heating device 10 is a rod-shaped body 50 having a diameter of about 6 mm, a rod-shaped body of 30 seconds or less, and sometimes 15 seconds or less.
50 can be softened by raising the temperature to 180 ° C.

Next, the microwave heating device 20 shown in FIG. 3 will be described.

In FIG. 3, a rod 50 is inserted into a metal cavity 21.
A window 22 is provided for inserting the information. A sealing ring for sealing the window 22 according to the wire diameter D of the rod 50 is provided on the window 22.
23 are installed.

Above the cavity 21, a magnetron 24 and a stirrer 25 are provided. The magnetron 24 radiates a microwave M from the antenna 26. Stirrer
25 rotates so that the heating of the rod 50 is performed uniformly.

Above the rod 50, a blocking plate 27 is provided. The blocking plate 27 blocks the microwave M and adjusts the length of the rod 50 to be heated.

The irradiation time of the microwave M is set based on a calibration curve previously obtained from the softening temperature range of the rod-shaped body 50 or the like.

In the microwave heating device 20, although it depends on the output, if the rod 50 has a wire diameter of about 6 mm, the rod 50 is heated to 180 ° C. and softened in about 2 minutes, and in some cases about 1 minute. The softened rod-shaped body 50 is bent by a molding device 30 described later.

Note that heating with high frequency is more excellent in workability and safety than heating with microwaves.

Next, the molding apparatus 30 shown in FIGS. 4 and 5 will be described.

In FIG. 4, a fixed mold 32 is fixed to a base 31 and movable molds 33, 34, and 35 divided into three are slidably mounted in a radial direction R of a rod-shaped body 50. . The fixed diameter 32 extends along the inner side 52 of the rod body 50 where the radius of curvature of the bent portion 51 is small. on the other hand,
The movable dies 33 to 35 press the outer side 53 of the rod-shaped body 50 having a large radius of curvature of the bent portion 51.

As shown in FIG. 5, stepped bolts 36 are fixed to the movable dies 33 to 35 from below. The head 36a and the shaft portion 36b of the stepped bolt 36 are guided by the groove 37 having a convex vertical cross section, so that the movable dies 33 to 35 are slidable in the radial direction R in FIG. The movable molds 33 to 35 move to the fixed mold 32 side by an input by a stepping through a link mechanism (not shown),
The side surface of the rod 50 is pressed. The movable mold 35 is a rod-shaped body.
It can also be moved in 50 axial directions S.

As shown in FIG. 5, a cooling water passage 38 through which cooling water flows is formed in each of the dies 32 to 35. This cooling water passage
Cooling water is introduced into 38 through the inlet pipe 39A in FIG. 4, and the cooling water is discharged from the outlet pipe 39B through the cooling water passage 38 (FIG. 5).

 Next, the bending process will be described.

The movable molds 33 to 35 are moved in a direction away from the fixed mold 32 in advance. After the heating portion of the rod 50 heated by the heating devices 10 and 20 in FIG. 1 or 3 is bent by hand, it is inserted between the fixed mold 32 and the movable molds 33 to 35 in FIG. Then, the rod-shaped body 50 is pulled in the axial direction S while holding both ends 54 of the rod-shaped body 50 by hand. Accordingly, the rod-shaped body 50 has a predetermined shape along the fixed mold 32 on the inner side 52 where the radius of curvature of the bending portion 51 is small. Thereafter, the movable molds 33 to 35 are pressed against the fixed mold 32 side, and at the same time, cooling water is caused to flow through the cooling water passage 38 (FIG. 5) to cool the rod-shaped body 50 via the molds 32 to 35. In this way, as shown in FIG. 6, a bar-shaped body 50 bent into a U-shape is obtained.

In the above configuration, the molding device 30 of FIG.
Since the cooling water passage 38 through which cooling water flows is formed in the rods 50 to 35, the rods 50 can be cooled while the rods 50 are bent along the two dies 32 to 35. Therefore, since the rod-like body 50 is cooled quickly, no deformation occurs later, so that the rod-like body 50 having a predetermined shape can be obtained quickly.

Meanwhile, it is conceivable that the inner fixed mold 32 in FIG. 4 is movably provided on the base 31 and the outer movable molds 33 to 35 are fixed. However, in order to bend the rod-shaped body 50 so as to follow the molds 32-35, the rod-shaped body 50 is pushed from the inside and the outer movable molds 33-35 are pushed.
It is easier to pull the two end portions 54 of the rod 50 and press it against the inner fixed die 32 than to make the rod 50 move along the fixed die 32.
In this state, the fixed mold 32 must be pressed and moved together with the rod-shaped body 50, and the workability deteriorates. On the other hand, in the molding apparatus 30 of the present invention, since the outer movable molds 33 to 35 can be freely moved, only the movable molds 33 to 35 need to be moved at the time of pressing, so that the workability is good.

 FIG. 7 shows a modification of the molding apparatus 30.

As shown in FIG. 8, this molding device 30 is for molding a rod-shaped body 50 having a shape folded in a loop. In the molding device 30 shown in FIG. 7, movable dies 34A and 34B are movable in the direction of arrow F. Further, a cooling water passage (not shown) is formed in the fixed mold 32 and the movable molds 34A and 34B. Fixed type 32
The cooling water is introduced into the cooling water passage from an introduction pipe (not shown) formed in the base 31. The other configuration is the same as that of the molding apparatus 30 in FIG. 4, and the same or corresponding portions are denoted by the same reference characters and description thereof will be omitted.

(Test example)

Hereinafter, test examples and comparative examples of the bending method of the present invention will be described to clarify the effects.

In the following examples, the physical properties of the fibers constituting the rod-shaped body and the method for producing the same are as follows.

Test fiber 1 (PVA fiber): As test fiber 1, polymerization degree 4500, saponification degree 99.9 mol%
The PVA fiber is obtained by wet spinning from a PVA aqueous solution. The test fiber 1 has a single fiber fineness of 1.8 denier, a tensile strength of 18.5 g / denier, an initial elastic modulus of 460 g / denier, and a cut elongation of 4.8%.

Test Fiber 2 (Wholly Aromatic Polyester Fiber): Test fiber 2 was prepared by melt-spinning using a molten liquid crystal polymer composed of a copolymer of P-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid. 300 with 1500 denier yarn
This is a wholly aromatic polyester fiber obtained by obtaining a filament and further performing a heat treatment at 290 ° C. for 24 hours in the air.
Test fiber 2 had a single fiber fineness of 5 denier and a tensile strength of 24.5.
g / denier, initial elastic modulus 650g / denier, breaking elongation 3.8%
It is.

Test Fiber 3 (Aromatic Polyamide Fiber): Kevlar (registered trademark) 49 manufactured by Toray DuPont was used as the test fiber 3. Test fiber 3 has a fiber diameter of 12 μm and a density of 1.
45, the tensile strength ^{21.5g / dr (280kg / mm 2} ), elastic modulus 996 g / dr
(13000 kg / mm ² ) and elongation at break 2.3%.

Test Examples 1 and 2 and Comparative Examples 1 to 5 Any one of the above test fibers 1 to 3 was used as a fiber constituting the rod-like body, and an epoxy resin (oil) was used as a thermosetting resin for binding the aligned assembly of the fibers. Shell Co., Ltd .: Epicoat (registered trademark) 828) was used. That is, first, a predetermined number of yarns are bundled, guided into a resin bath, impregnated with the resin, and passed through a molding nozzle. Then, the resin was cured in a heat radiation furnace at a resin curing temperature of 180 ° C., and a rod-shaped body having a circular cross section with a diameter of 6 mm was obtained in a manufacturing process of cooling. The fiber content volume% of the rod was adjusted to be 60% to 65%. The test fibers of Test Examples 1 and 2 and Comparative Examples 1 to 5 are as shown in FIG.

Each of the obtained FRP rods was heated by the following heater under the heating conditions shown in FIG. 9, and immediately after being heated, bent by a molding device shown in FIG. 4 and processed into the shape shown in FIG. The workability was determined.

Heater A (high-frequency dielectric heater): A high-frequency welder T-2000 manufactured by Pearl Industries was used as the heater A, and the heating conditions were a voltage of 200 V and OSCFREQ 38.8M.
The heating time was changed with Hz, input 5.3KVA and output 3KW.

Heater B (microwave heater): A modified microwave oven of National NE-300 was used as heater B, input voltage 100V, rated power consumption 930W,
Heating was performed under the conditions of an oscillation frequency of 245 MHz and an output of 500 W, and the heating time was changed.

Heating machine C (hot air heating machine): A heating furnace of a hot air circulation type which can be set at a predetermined temperature was used as the heating C, and the heating time was changed at the predetermined temperature.

The radius of curvature of the bent portion of the molding apparatus of FIG.
Was set to be 1.5 times the wire diameter, ie, 9 mm, and cooled.

 The conditions and the results obtained are shown in FIG.

In FIG. 9, the criteria for the bending workability are as follows.

◎: The rod-shaped body had no discoloration, had flexibility to be easily bent, and had no abnormality in the bent portion.

○: There is no discoloration of the rod-shaped body, but the flexibility is slightly less when set in the molding device, and the outside of the bent portion is whitened,
A wrinkle-like thing was seen inside.

Δ: Discoloration occurred in the rod-shaped body, the flexibility of the resin was lost, the adhesion was deteriorated, and a peeling phenomenon was observed between the layers at the bent portion.

X: The rod-shaped resin does not have flexibility, the fiber contained therein breaks, and no bending can be performed.

 FIG. 9 will be described.

In Comparative Example 1, high-frequency heating was performed for 20 minutes by the heater A, but the rod-shaped body was not softened and could not be bent at all. This is presumed to be due to the use of the rod-shaped body using the aromatic polyamide fiber as the test fiber 3. Note that 20
Even before the minute passed, it did not soften at all.

In Comparative Examples 2 and 4, since the hot-air heater was used as the heater C, the heating time of about 6 minutes did not allow the rod-shaped body to sufficiently heat up to the inside, resulting in insufficient bending workability. Disadvantages were seen.

On the other hand, as in Comparative Examples 3 and 5, the hot air heater was
When heated for 20 minutes, it becomes slightly easier to bend, but due to the external heating method, the surface of the rod becomes too hot, causing discoloration of the resin and residual strength of the rod (the ratio of the tensile strength of the rod before and after processing). ) Was significantly reduced.

Test Examples 3 and 4 Using the high-frequency induction heater A used in Test Example 1, the rods having a wire diameter of 6 mm obtained in Test Examples 1 and 2 were heated for 1 minute each, and the other heating conditions were tested. The heating was carried out under exactly the same conditions as in Example 1. Immediately after the rod is heated, the molding device shown in FIG.
Molded at 30. The major axis of the elliptical portion of the rod 50 in FIG. 8 was 3 cm, and the minor axis was 1.8 cm.

Also in this case, the rod-shaped body had good bending workability, and there was no problem such that no abnormality was observed in the bent portion.

As shown in FIG. 10, the rod-shaped body shown in FIG. 8 can be fitted into a stainless-steel clamp die 41 and can be easily fastened by a fastening member.

〔The invention's effect〕

As described above, according to the bending method of the present invention, a rod formed in advance can be quickly and easily bent to a required shape and dimensions at an execution site. In addition, the mechanical properties of the rod are not deteriorated. It goes without saying that the same effect can be obtained in a factory.

Further, according to the bending method of the invention (2) or the bending apparatus of the present invention, the rod-shaped body heated by the internal heating is cooled while being bent along the mold.
A rod having a predetermined shape can be obtained more quickly and easily.

In particular, according to the bending apparatus of the present invention, since the inside of the rod-shaped body having a small radius of curvature of the bent portion is made to follow the fixed die, the mounting of the rod-shaped body to the mold becomes easy, so that the workability is good. .

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing one embodiment of a high-frequency dielectric heating apparatus according to the present invention, FIG. 2 is a sectional view of a heating portion, and FIG.
FIG. 4 is a schematic structural view showing a microwave heating apparatus, FIG. 4 is a schematic plan view showing a first embodiment of a molding apparatus according to the present invention, FIG. 5 is a sectional view of the same, and FIG. FIG. 7 is a plan view showing a second embodiment of the molding apparatus, FIG. 8 is a plan view showing the shape of the obtained rod, FIG. 9 is a table showing a test example and a comparative example, FIG. 10 shows a clamping device using the obtained rod-like body. 10 ... High frequency heating device, 20 ... Microwave heating device, 30
…… Molding device, 31 …… Base, 32 …… Fixed type, 33-35,3
4A, 34B: movable type, 38: cooling water passage, 50: rod-shaped body,
51 …… Bending part, 52 …… Inner with small radius of curvature, 53…
… Outside with a large radius of curvature.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Mitsuo Mayahara 1-2-1, Kaigandori, Okayama City, Okayama Prefecture Inside Kuraray Co., Ltd. (72) Inventor Sumio Hattori 1-112, Umeda, Kita-ku, Osaka-shi, Osaka No. Kuraray Co., Ltd. (72) Inventor Yuichi Tanaka 1 Ao Nakadahara, Joetsu City, Niigata Prefecture Inside Arisawa Works, Ltd. (56) References JP-A-2-133347 (JP, A) JP, A) JP-A-59-42919 (JP, A)

Claims (5)

(57) [Claims] 1. A bundle of fibers containing an organic synthetic fiber having a tensile strength of 15 g / denier or more, a cut elongation of 3.5% or more, and an initial elastic modulus of 300 g / denier or more is radially bonded to each other with a thermosetting resin. By heating the preformed rod-shaped body by high-frequency dielectric heating or microwave heating at a temperature equal to or higher than the softening temperature of the thermosetting resin and equal to or lower than 200 ° C. for a predetermined time, A method for bending an FRP reinforcing bar, comprising a bending step of bending the rod-like body into a predetermined shape in a state where the thermosetting resin is softened. 2. The method according to claim 1, wherein the bending step comprises:
A method of bending an FRP reinforcing bar, wherein the rod is bent along a mold in a state where the thermosetting resin is softened by the heating step, and the rod is cooled along the die. 3. The method according to claim 1, wherein the organic synthetic fiber is a polyvinyl alcohol synthetic fiber. 4. The method according to claim 1, wherein the organic synthetic fiber is a wholly aromatic polyester synthetic fiber. 5. A high-frequency dielectric heating device or microwave heating device for heating a preformed rod by bonding a bundle of fibers containing organic synthetic fibers to each other with a thermosetting resin in a radial direction; A molding device, comprising: a molding device configured to mold the rod into a predetermined shape, wherein the molding device is fixed to a base, and has a fixed mold along a small radius of curvature of a bent portion of the rod-shaped body; A movable die that is slidably attached to the base and presses the outside of the bent portion of the rod-shaped body having a large radius of curvature, wherein the fixed die and the movable die have a cooling water passage through which cooling water flows. Bending equipment.