Fiber-reinforced resin bent pipe and its manufacturing method

Abstract

To enhance rigidity of an FRP-based bent pipe manufactured by connecting a plurality of FRP-based short pipes.SOLUTION: A laminate 2 for connecting FRP-based short pipes 1 is provided on an outer peripheral surface of the plurality of FRP-based short pipes 1 constituting an FRP-based bent pipe. A glass mat, which is a sheet body forming an inner mat layer 2a of the laminate 2, and a glass cloth, which is a sheet body forming an outer reinforcing fiber layer 2b, are each impregnated with resin and are wound spirally from one end side of the bent pipe to the other side seamlessly with end parts in a width direction overlapping each other. Therefore, it is possible to obtain higher rigidity than when the reinforcing fiber layer is formed from a plurality of sheets that are not sewn together.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a fiber-reinforced plastic bent pipe manufactured by joining a plurality of short fiber-reinforced plastic pipes, and a manufacturing method thereof. [Background technology]

[0002] Fiber-reinforced plastic (FRP) pipes are lighter and more corrosion-resistant than metal pipes, and are therefore widely used in the field of water transport pipes. When laying FRP pipes as water transport pipes, at the point where the direction of the pipe changes, fiber-reinforced plastic bent pipes (FRP bent pipes) are usually used, in which multiple fiber-reinforced plastic short pipes (FRP short pipes), at least one end of which is inclined with respect to the pipe axis direction, are joined with their end faces butted together to form a curved pipe. This is because it is technically difficult to manufacture a smooth arc-shaped pipe (smooth bend pipe) from a single FRP pipe.

[0003] The manufacturing method for this FRP bent pipe typically involves cutting a straight FRP pipe at a predetermined angle to the axial direction of the pipe to produce a number of short FRP pipes as described above, and then joining these short FRP pipes by butting them together as described above and forming a connecting layer on the outer surface of each butted joint.

[0004] For example, in Patent Document 1 and the like, a laminate is formed on the outer surface of the butt joint as a connecting layer for joining FRP short pipes, in which a mat layer with random fiber orientation and a cross-woven reinforcing fiber layer are laminated. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 5837628 Summary of the Invention [Problem to be solved by the invention]

[0006] The manufacturing method of the FRP bent pipe in Patent Document 1 involves first joining two short FRP pipes, then repeating the process of joining one of the short FRP pipes to another short FRP pipe to produce a curved pipe of a predetermined length. In the FRP bent pipe manufactured in this way, the laminates that join adjacent short FRP pipes are formed separately for each joint, which leaves room for improvement in terms of the rigidity of the entire pipe.

[0007] Therefore, an object of the present invention is to increase the rigidity of an FRP bent pipe manufactured by joining a plurality of FRP short pipes. [Means for solving the problem]

[0008] In order to solve the above problems, the fiber-reinforced resin bent pipe (FRP bent pipe) of the present invention is a fiber-reinforced resin bent pipe in which a plurality of fiber-reinforced resin short pipes (FRP short pipes) with at least one end face inclined with respect to the pipe axis direction are butted together to form a bent pipe as a whole, and the outer circumferential surface of each of the fiber-reinforced resin short pipes has a laminate in which a mat layer with random fiber orientation and a woven or knitted reinforcing fiber layer are laminated. The mat layer and the reinforcing fiber layer are each made of a sheet body, and at least the sheet body forming the reinforcing fiber layer is wound in a spiral shape without a break from one end side to the other end side (Configuration 1). Here, "without a break" includes not only that the sheet body is an integrated one without a break, but also that a plurality of sheets are sewn together. In addition, the FRP bent pipe and the FRP short pipe include an FRPM bent pipe and an FRPM short pipe in which the pipe body is formed of an FRP layer and a mortar layer sandwiched between them (the same applies below).

[0009] In other words, of the laminates laminated on the outer peripheral surfaces of multiple FRP short pipes that make up the FRP bent pipe, at least the sheet body that forms the reinforcing fiber layer is wrapped spirally without interruption from one end to the other end of the FRP bent pipe, thereby achieving higher rigidity than when the reinforcing fiber layer is formed from multiple sheets that are not sewn together.

[0010] In addition, in the above-mentioned configuration 1, the rigidity can be further increased by configuring (configuration 2) in which not only the sheet body forming the reinforcing fiber layer but also the sheet body forming the mat layer is spirally wound without interruption from one end side to the other end side of the FRP bent pipe.

[0011] Here, in the above-mentioned configuration 1 or 2, it is preferable that the sheet body forming the reinforcing fiber layer is wound in a form in which its width direction ends overlap (configuration 3). Also, in the above-mentioned configuration 2 or 3, when the sheet body forming the mat layer is wound spirally without interruption, it is preferable that the sheet body is wound in a form in which its width direction ends overlap (configuration 4).

[0012] In any of the above configurations 1 to 4, it is preferable that the innermost layer of the laminate is composed of the mat layer (configuration 5). This is because, when used as a water transport pipe, it is advantageous to ensure watertightness by using the mat layer as the innermost layer.

[0013] The manufacturing method of a fiber-reinforced resin bent pipe of the present invention, in the manufacturing method of a fiber-reinforced resin bent pipe of any of the above configurations 1 to 5, comprises temporarily fixing the multiple fiber-reinforced resin short pipes to form a temporary bent pipe, and then winding a sheet body forming the mat layer and a sheet body forming the reinforcing fiber layer in a resin-impregnated state in a spiral shape without interruption from one end side to the other end side of the temporary bent pipe. Effect of the Invention

[0014] As described above, in the present invention, of the mat layer and reinforcing fiber layer laminated on the outer peripheral surface of the FRP bent pipe, at least the sheet body forming the reinforcing fiber layer is wound spirally without interruption from one end to the other end, thereby increasing the rigidity of the FRP bent pipe compared to when the reinforcing fiber layer is formed from multiple sheets that are not sewn together. [Brief description of the drawings]

[0015] [Figure 1] A longitudinal sectional view of an embodiment of an FRP bent pipe [Diagram 2] Enlarged longitudinal sectional view of the main part of Figure 1 [Diagram 3] Front view of the FRP bend in Figure 1 [Figure 4] Fig. 1: Perspective view of the FRP bent pipe DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows approximately half of one end of an FRP bent pipe according to an embodiment. This FRP bent pipe is for use as a water transport pipe, and is made by joining two types of FRP short pipes 1 (1a and 1b) with their end faces butted together to form a bent pipe. The angle between the two adjacent FRP short pipes 1 in the pipe axis direction (the angle at each section) is not particularly limited. In the following, the FRP bent pipe will be simply referred to as a "bent pipe" and the FRP short pipe will be simply referred to as a "short pipe." In addition, of the short pipes 1, those disposed at both ends of the bent pipe will be referred to as the connecting short pipes 1a, and those disposed in the middle of the bent pipe, i.e., between the two connecting short pipes 1a, will be referred to as the intermediate short pipe 1b.

[0017] Each of the short pipes 1 is manufactured by cutting a straight FRP pipe at a specified angle with respect to the pipe axis direction. Of these, the connecting short pipe 1a has only one end face inclined with respect to the pipe axis direction, and the other end side is connected via a connecting pipe to the FRP straight pipe that constitutes the straight section of the water transport pipe (not shown). Meanwhile, the intermediate short pipe 1b is shorter than the connecting short pipe 1a, has both end faces inclined with respect to the pipe axis direction, and is joined to the adjacent connecting short pipe 1a or intermediate short pipe 1b.

[0018] A laminate 2 for joining the short pipes 1 is formed on the outer circumferential surface of each of the short pipes 1 which are connected together to form a curved pipe as a whole.

[0019] As shown in Fig. 2, the laminate 2 is made by laminating a mat layer 2a made by resin-impregnating a glass mat, which is a cloth-like sheet (sheet body) with random fiber orientation, and a reinforcing fiber layer 2b made by resin-impregnating a glass cloth, which is a woven reinforcing fiber sheet (sheet body), with the mat layer 2a suitable for ensuring watertightness as the inner layer and the reinforcing fiber layer 2b suitable for increasing the bonding strength as the outer layer. Note that unsaturated polyester resin is used as the resin with which the glass mat and glass cloth are impregnated.

[0020] As shown in Figures 2 to 4, the glass mat forming the mat layer 2a and the glass cloth forming the reinforcing fiber layer 2b are spirally wound without gaps from one end to the other with their widthwise ends overlapping.

[0021] In the manufacturing method of this FRP bent pipe, first, a plurality of short pipes 1 are butted together at their ends to form a curved pipe of a predetermined length, and then temporarily fixed in this state to form a temporary bent pipe. Next, a resin-impregnated band-shaped glass mat is wound around the outer circumferential surface of the temporary bent pipe in a spiral manner from one end side to the other end side of the temporary bent pipe without any gaps and with the widthwise ends overlapping to form a mat layer 2a. Then, a resin-impregnated band-shaped glass cloth is wound around the surface of the mat layer 2a in a spiral manner from one end side to the other end side of the temporary bent pipe without any gaps and with the widthwise ends overlapping to form a reinforcing fiber layer 2b. This results in an FRP bent pipe in which each short pipe 1 is joined by a laminate 2 consisting of the mat layer 2a and the reinforcing fiber layer 2b.

[0022] This FRP bend pipe has the above-mentioned structure, and the mat layer 2a and the reinforcing fiber layer 2b constituting the laminate 2 on the outer periphery are formed by spirally winding the glass mat and the glass cloth from one end to the other end without any breaks and with the widthwise ends overlapping, so that it has higher rigidity than a conventional one in which each layer constituting the laminate is formed from a plurality of sheets that are not sewn together, and deflection during use is effectively suppressed. In addition, by improving the longitudinal strength of the bend pipe, it is possible to improve the resistance to the centrifugal force caused by the water flow and the thrust force generated by uneven water pressure compared to the conventional one. Therefore, when it is used for buried purposes, it may be possible to omit pouring protective concrete to suppress deflection of a normal bend pipe.

[0023] Here, the glass mat forming the mat layer can be replaced with other sheet bodies having random fiber orientation, and the glass cloth forming the reinforcing fiber layer can be replaced with other woven sheet bodies (roving cloth, etc.) or knitted sheet bodies.

[0024] The arrangement of the mat layer and the reinforcing fiber layer in the laminate can be changed as desired, but from the viewpoint of ensuring watertightness, it is preferable to arrange the mat layer as the innermost layer as in the embodiment.

[0025] In order to further improve the watertightness of the FRP bent pipe, a mat layer made of a sheet body having random fiber orientation may be provided on the inner peripheral surface of the butted portion of each of the FRP short pipes 1 .

[0026] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims, not by the above meaning, and is intended to include all modifications within the scope and meaning equivalent to the claims.

[0027] For example, in the embodiment, both the mat layer and the reinforcing fiber layer are formed from a sheet body that is spirally wound without gaps from one end to the other end and with the widthwise ends overlapping. However, as long as at least the sheet body forming the reinforcing fiber layer is spirally wound without gaps from one end to the other end, the rigidity can be increased compared to conventional ones.

[0028] In addition, the method of spirally winding the mat layer or the reinforcing fiber layer is not limited to that in the embodiment, and may be any method as long as the sheet body that forms the mat layer or the reinforcing fiber layer on the target portion of the bent pipe is wound so that no gaps are ultimately generated, including partial spiral winding. For example, the spiral winding in a form in which the width direction ends of the sheet body do not overlap can be repeated from one end side to the other end side of the temporary bent pipe and from the other end side to the one end side so that no gaps are ultimately generated.

[0029] In addition, in the embodiment, a sheet body forming a mat layer is wrapped around the outer peripheral surface of the temporary bent pipe, and then a sheet body forming a reinforcing fiber layer is wrapped around that surface. However, the sheet body forming the mat layer and the sheet body forming the reinforcing fiber layer may be overlapped in advance, and the two overlapped sheet bodies may be simultaneously wrapped around the outer peripheral surface of the temporary bent pipe. [Explanation of symbols]

[0030] 1 FRP short tube 1a Short connection pipe 1b Intermediate short pipe 2. Laminate 2a Matte layer 2b Reinforcement fiber layer

Claims

1. A composite pipe made of reinforced plastics is provided with a laminate in which a mat layer having random fiber orientation and a woven or knitted reinforcing fiber layer are laminated on the outer circumferential surface of each of the short pipes made of reinforced plastics, the short pipes being butted against each other so that the end faces of the short pipes made of reinforced plastics are curved as a whole, the mat layer having random fiber orientation and the woven or knitted reinforcing fiber layer are laminated on the outer circumferential surface of each of the short pipes made of reinforced plastics, the mat layer and the reinforcing fiber layer are each formed of a sheet body, and the sheet body forming the mat layer and the reinforcing fiber layer is wound in a spiral shape without interruption from one end side to the other end side, The innermost layer of the laminate is composed of the mat layer, A bent pipe made of reinforced plastic composite pipes, characterized in that the sheet body forming the mat layer is wound in a form in which its widthwise ends overlap, and the sheet body forming the reinforcing fiber layer is wound in a form in which its widthwise ends overlap, and the overlap of the widthwise ends of the sheet body forming the mat layer and the overlap of the widthwise ends of the sheet body forming the reinforcing fiber layer overlap in the pipe axial direction.

2. 2. The method for manufacturing a bent pipe made of a reinforced plastic composite pipe as described in claim 1, wherein a plurality of the short pipes made of the reinforced plastic composite pipe are temporarily fixed to form a temporary bent pipe, a resin-impregnated sheet body having random fiber orientation is spirally wound around the outer peripheral surface of the temporary bent pipe from one end side to the other end side of the temporary bent pipe without gaps and with widthwise ends overlapping to form a mat layer, and a resin-impregnated woven or knitted sheet body is spirally wound around the surface of the mat layer without gaps and with widthwise ends overlapping to form a reinforcing fiber layer, thereby forming a laminate in which the overlapping positions of the widthwise ends of the sheet body forming the mat layer and the overlapping positions of the widthwise ends of the sheet body forming the reinforcing fiber layer overlap in the pipe axial direction.

3. A method for manufacturing a curved pipe made of reinforced plastic composite pipe, in which end faces of short pipes made of reinforced plastic composite pipes formed of a plurality of fiber-reinforced resin layers and mortar layers, at least one end face of which is inclined with respect to the pipe axial direction, are butted together so that the end faces form a curved pipe as a whole, and the outer surface of each of the short pipes made of reinforced plastic composite pipes has a laminate in which a mat layer having random fiber orientation and a woven or knitted reinforcing fiber layer are laminated, wherein a plurality of the short pipes made of reinforced plastic composite pipes are temporarily fixed to form a temporary curved pipe, and then a sheet body forming the mat layer and a sheet body forming the reinforcing fiber layer are repeatedly wound in a resin-impregnated state from one end side to the other end side of the temporary curved pipe and from the other end side to the one end side, in a manner such that no gaps are ultimately generated.

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