JP3817149B2 - Manufacturing method of FRP pipe - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method of manufacturing an FRP pipe used as a bridge girder of an FRP (Fiber Reinforced Plastic) bridge, a pipe for transporting liquid, or the like.
[0002]
[Prior art]
Pipe-shaped FRP is used as various civil engineering structures such as liquid transport pipes. As one of methods for manufacturing such an FRP pipe, for example, a filament winding method is known. In this method, a continuous fiber bundle or the like is wound around a metal core while being impregnated with a liquid resin mixed with a catalyst or a curing agent in advance, and is cured after being made to have a predetermined thickness, and then demolded to obtain an FRP pipe. However, when an FRP pipe is manufactured by the filament winding method, there is a problem that the length of the pipe can only be about the length of the core metal.
[0003]
As a method for solving such a problem that the length of the pipe is limited, a pultrusion method is used. In this method, fiber reinforcing materials (continuous fiber bundles, mat-like fiber base materials, etc.) are constructed according to strength characteristics and drawn, and while being drawn, they are impregnated with a liquid resin mixed with a catalyst and a curing agent in advance and heated. The FRP pipe is continuously obtained by curing while passing through the mold. According to this method, the length of the FRP pipe is not limited, and the length of the FRP pipe can be freely adjusted by cutting the drawn long molded product with a cutter or the like.
[0004]
[Problems to be solved by the invention]
However, the conventional drawing method has the following problems. In other words, the braid is composed of continuous fiber bundles whose axes are oriented in a plurality of directions, but when drawing the braid into the mold, there is a problem of causing a so-called misalignment in which the positions of the intersecting continuous fiber bundles are shifted. was there. If the continuous fiber bundle is misaligned, the orientation balance of the continuous fiber bundle constituting the FRP pipe is lost. Especially, the portion where the continuous fiber bundle is shifted and the resin is locally increased is weak in strength and breaks from that portion. Is likely to advance.
[0005]
The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a method for manufacturing an FRP pipe that can suppress misalignment of a braid during pultrusion molding.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a method for manufacturing an FRP pipe obtained by impregnating a resin into a braided fabric, wherein the braided fabric includes a layer composed of a plurality of continuous fiber bundles having the same axial direction. Three or more different bundles are provided so that the axial direction of the continuous fiber bundles included in both outermost layers in the overlapping direction is one direction, and is assembled along one direction. It is characterized in that it includes the step of drawing the cloth through a mold and making it into a pipe shape.
[0007]
In the FRP pipe manufacturing method of the present invention, the braided fabric is pulled out along one axial direction among the continuous fiber bundles in a plurality of directions, so that no force is applied in the direction of obliquely shifting the continuous fiber bundles. Difficult to cause misalignment.
[0008]
In the FRP pipe manufacturing method of the present invention, the basis weight of another continuous fiber bundle having an axial direction different from that of the one continuous fiber bundle is larger than the basis weight of the continuous fiber bundle in the one direction. It is good.
[0009]
In this case, since the basis weight of the continuous fiber bundle in the circumferential direction of the obtained FRP pipe becomes larger than the basis weight of the continuous fiber bundle in the axial direction, the strength in the circumferential direction of the pipe can be improved. For this reason, even if the FRP pipe obtained by the above-described method is used as a liquid transport pipe to which a large internal pressure is applied, the occurrence of breakage in the circumferential direction of the pipe can be suppressed.
[0010]
Moreover, in the manufacturing method of the FRP pipe of this invention, a braid is a continuous fiber bundle with which the axial direction inclined 30 degrees-60 degrees with respect to the axial direction of one continuous fiber bundle, and -30 degrees--60 degrees. An inclined continuous fiber bundle, and a continuous fiber bundle inclined by 75 ° to 105 °, and a continuous fiber bundle inclined by 30 ° to 60 ° when the basis weight of the continuous fiber bundle in one direction is 1. The total of the basis weight, the basis weight of the continuous fiber bundle tilted by −30 ° to −60 °, and the basis weight of the continuous fiber bundle tilted by 75 ° to 105 ° may be 1.5 or more.
[0011]
As a result of the analysis using the finite element method of the present inventors, when the ratio of the basis weight of each continuous fiber bundle was set to such a value, the FRP pipe was excellent in the balance of strength in the axial direction and the circumferential direction. It turned out to be something. In the numerical analysis of the finite element method, the objective function was the strength of the FRP pipe, the design variable was the orientation and configuration of the continuous fiber bundle, and the numerical experiment was repeated so that the strength of the FRP pipe as the objective function was maximized.
[0012]
In the FRP pipe manufacturing method of the present invention, the continuous fiber bundle in the direction with the larger basis weight may have a higher tex count than the continuous fiber bundle in the direction with the smaller basis weight. In this way, the basis weight can be increased by adjusting the tex count.
[0013]
Further, in the method for producing an FRP pipe of the present invention, before the drawing through the mold, the braid is subjected to a needling treatment, and before or simultaneously with the drawing, the braid is impregnated with the molten resin. Is preferred.
[0014]
By performing the needling treatment and opening the fiber, the resin impregnation property can be improved, and the adhesion at the intersection of the braided fabric can be improved to prevent misalignment.
[0015]
In the FRP pipe manufacturing method of the present invention, the braided fabric is a triaxial braided fabric or a four-shaft braided fabric, and a mat-like fiber substrate such as a continuous strand mat is stacked on the braided fabric. Drawing is preferably performed.
[0016]
Thus, the appearance quality and strength of the FRP pipe can be improved by overlapping the mat-like fiber base material on the braided fabric.
[0017]
The continuous fiber bundle can be formed of glass fiber, carbon fiber, alumina fiber, aramid fiber, or the like.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of a method for producing an FRP pipe according to the present invention will be described in detail with reference to the accompanying drawings. In addition, the same code | symbol shall be used for the same element and the overlapping description is abbreviate | omitted.
[0019]
FIG. 1 is a schematic configuration diagram of a pultrusion apparatus 10 for manufacturing the FRP pipe of the present embodiment. In the present embodiment, a four-axis assembly fabric (also referred to as a four-axis nonwoven fabric) 20 composed of continuous glass fibers and a continuous strand mat 30 that is a mat-like fiber substrate formed of glass fibers are stacked. Pull out things to make FRP pipes. The continuous strand mat 30 is obtained by dispersing glass continuous fibers randomly and uniformly and matting with a binder, and is arranged so as to cover the front and back surfaces of the four-axis assembly fabric 20.
[0020]
The pultrusion molding apparatus 10 includes a resin tank 40 containing a molten resin 42 mixed with a catalyst and a curing agent, a mold 50 in which a cylindrical drawing passage is formed, a four-axis assembly fabric 20 and a continuum. A puller 60 that pulls out the asstrand mat 30 through the mold 50 and a cutting machine 70 that cuts the FRP formed in a pipe shape to a desired length are provided.
[0021]
On the upstream side of the resin tank 40, a slit member 44 for laminating the continuous strand mat 30 on the front and back surfaces of the four-axis assembly fabric 20 and immersing the continuous strand mat 30 in the resin tank 40 is provided. However, the slit member 44 is not necessarily provided. As the molten resin 42 to be retained in the resin tank 40, various thermoplastic resins such as thermosetting resins such as unsaturated polyester resins, vinyl ester resins, phenol resins, epoxy resins, and methacrylate resins, and nylon resins and polypropylene resins. Can be used.
[0022]
The mold 50 located downstream of the resin tank 40 is formed of SKD or SCM die steel, and a cylindrical passage is formed by fastening the upper mold 50a and the lower mold 50b. Further, the molded product passing through the mold 50 is heated by the heater 52, and the resin impregnated in the four-axis assembly fabric 20 is cured. Upstream of the mold 50, the molten resin 42 is infiltrated into the 4-axis assembly fabric 20 and the continuous strand mat 30, the excess molten resin 42 is removed, and the 4-axis assembly fabric 20 and the like are removed from the mold 50. A roller group 54 composed of three rollers for introduction into the passage is provided.
[0023]
The puller 60 is a so-called caterpillar type in which a molded product that has passed through a mold is sandwiched from above and below by a rotating roller. The puller 60 may be a so-called clamp unit system in which a molded product is pulled out by two clamps that reciprocate mechanically and hydraulically. The cutting machine 70 rotates the blade with the driving force of the motor M to cut the molded product.
[0024]
Next, with reference to FIG. 2, the 4-axis assembly fabric 20 is demonstrated. The four-axis braided fabric 20 includes, in order from the top, a warp 11 as a continuous glass fiber bundle, a weft 12 inclined by 90 ° thereto, an oblique yarn 13 inclined by −45 ° with respect to the warp 11, and a warp 11 An oblique thread 14 inclined by 45 °, a weft 15 inclined by 90 ° with respect to the warp 11, and a warp 16 parallel to the warp 11 are provided. The yarns that overlap vertically are bonded by resin.
[0025]
In the present embodiment, each continuous fiber bundle constituting the four-axis assembly fabric 20 is formed of glass fibers, but may be formed of carbon fibers, alumina fibers, aramid fibers, or the like.
[0026]
Further, the four-axis assembly fabric 20 is arranged such that the drawing direction in the mold 50 is the direction of the arrow A in FIG. That is, the molded product is pulled out along the axial direction (in other words, the longitudinal direction) of the warps 11 and 16.
[0027]
Further, the basis weights of the yarns in the direction different from the drawing direction, that is, the other oblique yarns 13 and 14 and the wefts 12 and 15 are larger than the basis weights of the warp yarns 11 and 16. Specifically, the tex count (weight (g) per 1000 m of strands) of the oblique yarns 13 and 14 and the weft yarns 12 and 15 is increased to increase the basis weight. Here, the basis weight referred to in the present invention means the weight per unit area (1 m ² ) of an assembly of continuous fiber bundles (for example, an assembly of warps 11) oriented in the same direction. More specifically, the configuration of the four-shaft fabric 20 will be described. When the basis weight of the warps 11 and 16 is 1, the total amount of the basis weights of the oblique yarns 13 and 14 and the basis weight of the wefts 12 and 15 is 1.5. This is the relationship. Preferably, the basis weight of the warps 11 and 16, the basis weight of the oblique yarn 13, the basis weight of the oblique yarn 14, and the basis weight of the warp yarns 12 and 15 are preferably 1: 1: 1: 2. .
[0028]
The above is the configuration of the pultrusion apparatus 10 and the four-axis assembly fabric 20 used in the present embodiment. Next, the manufacturing method of the FRP pipe of this embodiment is demonstrated.
[0029]
First, the puller 60 is driven to rotate, and the 4-axis assembly fabric 20 and the continuous strand mats 30 and 30 wound in a drum shape are pulled out. Thereafter, the mats 30, 30 are overlapped by the slit member 44 so as to cover the front and back surfaces of the four-axis assembly fabric 20, and are impregnated in the molten resin 42 in the resin tank 40.
[0030]
The 4-axis assembly fabric 20 and the like that have passed through the resin tank 40 are pressed into contact with each other by the roller group 54 and the resin penetrates into the interior, and is drawn into the cylindrical passage of the mold 50. At this time, the laminate of the four-axis assembly fabric 20 and the mat 30 is pulled out while being rounded into a cylindrical shape following the path of the mold 50. Further, in the subsequent stage of the mold 50, the molded product is heated by the heater 52, and the impregnated molten resin 42 is cured.
[0031]
Here, as described above, since the four-axis assembly fabric 20 is pulled out along the axial direction of the warp yarns 11 and 16, no force is applied in a direction in which the warp yarns 11 and 16 are shifted obliquely, and misalignment is unlikely to occur. . For this reason, it is possible to smoothly perform the drawing operation of the molded product.
[0032]
The long molded product drawn from the mold 50 is cut into a desired length by the cutting machine 70, and the target FRP pipe 80 can be obtained.
[0033]
FIG. 3 shows a perspective view of the obtained FRP pipe 80, and FIG. 4 shows an enlarged view of the region S in FIG. As shown in FIG. 3, the FRP pipe 80 has a flat portion 82 formed on the inner side of the pipe in order to improve the strength as a wrap portion between the four-axis assembly fabric 20 and the continuous strand mat 30. Further, as shown in FIG. 4, the FRP pipe 80 includes, in order from the outside, a mat 30, a warp 11 layer, a weft 12 layer, an oblique yarn 13 layer, an oblique yarn 14 layer, a weft 15 layer, It has a laminated structure of a warp 16 layer and a mat 30. Thus, the appearance quality and strength of the FRP pipe 80 can be improved by stacking the continuous strand mat 30 that is easily impregnated with the molten resin 42 on the four-axis assembly fabric 20.
[0034]
Here, in this embodiment, since the basis weight of each yarn in the circumferential direction of the FRP pipe 80 is larger than the basis weight of the warp yarns 11 and 16 in the axial direction, the strength in the circumferential direction of the FRP pipe 80 is high. It is a thing. For this reason, even if the FRP pipe 80 is used as a liquid transport pipe or the like to which a large internal pressure is applied, it is possible to prevent the FRP pipe 80 from being broken in the circumferential direction.
[0035]
Further, when an internal pressure is applied to a pipe having a closed cross section, the stress applied in the circumferential direction is approximately twice the stress applied in the axial direction of the pipe. As described above, the basis weights of the warps 11 and 16 are set to 1, and the basis weights of the oblique threads 13 and 14 whose axial directions are inclined by −45 ° and 45 °, respectively, are inclined by 90 ° with respect to this. When the total value of the basis weights of the wefts 12 and 15 is 1.5 or more, the balance of strength in the axial direction and the circumferential direction of the FRP pipe 80 is excellent. This is a matter found by the present inventors as a result of analysis using the finite element method. Preferably, the basis weight of the warp yarns 11 and 16, the basis weight of the oblique yarn 13 whose axial direction is inclined by -45 °, the basis weight of the oblique yarn 14 inclined by 45 ° relative to the warp yarn, and the warp yarn The ratio of the basis weights of the wefts 12 and 15 inclined 90 ° is preferably 1: 1: 1: 2.
[0036]
The oblique yarn 13, the oblique yarn 14, and the warp yarns 12 and 15 do not necessarily have to be inclined at −45, 45 °, and 90 ° with respect to the warp yarns 11 and 16, respectively. The same effect can be obtained if it has inclinations of °, 30 ° to 60 °, and 75 ° to 105 °.
[0037]
Furthermore, in this embodiment, before drawing through the mold 50, the braid 20 may be subjected to a needling treatment to be opened. By performing the needling treatment in this way and performing the fiber opening treatment, the resin impregnation property is enhanced, and the adhesion at the intersection of the braided fabric is improved, thereby preventing misalignment.
[0038]
Moreover, according to this embodiment, the following effects can also be acquired. That is, in the conventional pultrusion method, the continuous fiber bundle, which is the main component of the pultruded product, greatly contributes to the strength in the longitudinal direction of the pultruded product, and the steel material has a specific weight of about 1/4 of the steel material. Although equivalent strength can be realized, on the other hand, there is a drawback that the strength in the direction perpendicular to the longitudinal direction of the pultruded product is extremely weak. The biggest factor was that the continuous fibers were oriented in the longitudinal direction of the pultruded product. In particular, when internal pressure is applied to a square pipe or cylindrical pipe with a closed cross section, it is known that the generated stress value is twice as long as the stress value in the circumferential direction perpendicular to the longitudinal direction. The improvement was strongly desired.
[0039]
In the conventional pultrusion method, in order to solve such a problem, continuous strand mats in which continuous fibers are randomly and uniformly dispersed and matted with a binder, or strands are cut short and randomly and uniformly. A chopped strand mat dispersed in a binder and matted with a binder was used in combination with a continuous fiber bundle. However, the strength in the direction orthogonal to the longitudinal direction of the pultruded product cannot be sufficiently improved only by using such a mat-like reinforcing material together with the continuous fiber bundle, and cracks in the orthogonal direction are prevented. Only a moderate effect could be expected.
[0040]
For this reason, conventionally, the strength in the longitudinal direction and the circumferential direction has been improved by carrying out a two-stage operation of further wrapping glass fibers in the circumferential direction of the pipe obtained by the pultrusion method. However, when carrying out such a two-stage operation, there is a problem that a facility for winding is required in addition to the pultrusion molding apparatus, and the entire apparatus becomes large. In addition, incidental facilities such as base material supply facilities have become large, resulting in a large capital investment and a significant decrease in molding workability compared to ordinary pultrusion methods alone. There was a problem to do.
[0041]
On the other hand, in the present embodiment, at least two or more of the continuous fibers provided in three or more directions are arranged in an oblique direction with respect to the longitudinal direction of the pipe. The strength of the FRP pipe in the circumferential direction can be improved without performing work. Further, the equipment for winding the glass fiber is not necessary, and the cost can be greatly reduced.
[0042]
As mentioned above, although the invention made by the present inventors has been specifically described based on the embodiment, the present invention is not limited to the above embodiment. For example, the step of impregnating the molten resin into the fabric may be performed at the same time as the drawing without adopting a configuration in which the molten resin is poured into a mold, not before the drawing. Moreover, the braiding used for the FRP pipe is not limited to the four-shaft braiding, and may be any one having three or more axes such as a triaxial braiding.
[0043]
Further, the FRP pipe may be formed into a rectangular tube shape or the like by variously changing the cross-sectional shape of the passage in the mold through which the braid is pulled out.
[0044]
【The invention's effect】
As described above, according to the method for manufacturing an FRP pipe of the present invention, the braided fabric is pulled out along one axial direction among the continuous fiber bundles in a plurality of directions. No force is applied to the lens, and misalignment can be prevented.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing a pultrusion apparatus used in a method for producing an FRP pipe of the present invention.
FIG. 2 is a plan view showing a braid (four-axis braid) used in the present invention.
FIG. 3 is a perspective view showing the obtained FRP pipe.
4 is an enlarged view of a region S shown in FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Pull-out molding apparatus, 11 ... Warp (0 degree), 12 ... Weft (90 degree), 13 ... Oblique thread (-45 degree), 14 ... Oblique thread (45 degree), 15 ... Weft (90 degree) , 16 ... Warp (0 °), 20 ... 4-axis braid (braid), 30 ... Continuous strand mat (mat-like fiber substrate), 40 ... Resin tank, 42 ... Molten resin, 44 ... Slit member , 50 ... mold, 52 ... heater, 54 ... roller group, 60 ... puller, 70 ... cutting machine, 80 ... FRP pipe, A ... axial direction of warp.

Claims (5)

In the manufacturing method of the FRP pipe formed by impregnating the fabric with resin,
The braided fabric includes a plurality of layers of continuous fiber bundles having the same axial direction stacked so that three or more of the axial directions are different from each other, and both outermost layers in the overlapping direction of the continuous fiber bundles The axial direction of what is included in is composed of one direction,
A method of manufacturing an FRP pipe, comprising a step of drawing the braided fabric through a mold along the one direction to form a pipe. 2. The method for manufacturing an FRP pipe according to claim 1, wherein the basis weight of another continuous fiber bundle having an axial direction different from that of the one continuous fiber bundle is larger than the basis weight of the continuous fiber bundle in the one direction. . The braided fabric has a continuous fiber bundle whose axial direction is inclined by 30 ° to 60 ° with respect to the axial direction of the one continuous fiber bundle, a continuous fiber bundle inclined by −30 ° to −60 °, and 75 ° to A continuous fiber bundle inclined by 105 °,
When the basis weight of the continuous fiber bundle in the one direction is 1, the basis weight of the continuous fiber bundle inclined by 30 ° to 60 °, the basis weight of the continuous fiber bundle inclined by −30 ° to −60 °, 3. The method of manufacturing an FRP pipe according to claim 1, wherein a total basis weight of the continuous fiber bundle inclined by 75 ° to 105 ° is 1.5 or more. Before the drawing through the mold, the braided fabric is subjected to needling treatment, and before or simultaneously with the drawing, the braided fabric is impregnated with a molten resin. Item 4. The method for producing an FRP pipe according to any one of Items 3 to 3. The said assembly is a triaxial assembly fabric or a 4-axis assembly fabric, The mat-like fiber base material is piled up on the said assembly fabric, and the said extraction is carried out, The Claim 1-Claim 4 characterized by the above-mentioned. The manufacturing method of the FRP pipe as described in any one.

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