JP5837628B2 - Fiber reinforced plastic curved pipe - Google Patents

Description

  The present invention relates to a fiber reinforced plastic bent pipe used for a hydraulic pipe or the like of a hydroelectric power plant.

  FRP pipes made of fiber reinforced plastic (FRP) are widely used in the field of water transport pipes because they are lighter and have better corrosion resistance than metal pipes. When piping an FRP pipe as a water transport pipe, a plurality of fiber reinforced plastic short pipes (FRP short pipes) having at least one end face inclined with respect to the pipe axis direction are usually located at positions where the direction of the pipe line changes. The fiber reinforced plastic curved pipe (FRP curved pipe) is used in which the end faces are joined to each other so as to form a curved pipe. This is because it is technically difficult to manufacture a smooth arc-shaped tube (generally referred to as a smooth bend tube) with a single FRP tube.

  This FRP bent pipe is usually manufactured by cutting a straight FRP pipe at a predetermined angle with respect to the pipe axis direction in advance to produce a plurality of the above FRP short pipes. In a state where the short pipes are butted as described above, bonding is performed by forming a connection layer such as a resin on the outer peripheral surface of each butted portion (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 10-305481 (FIG. 7)

  By the way, when the FRP bent pipe manufactured by the method as described in Patent Document 1 is used for agricultural waterways and sewers, an angle formed by the pipe axis directions of two adjacent FRP short pipes (for each node). Is set at 30 degrees or less. However, normally, as shown in FIG. 5, for example, the angle swing θ for each node is set to be relatively large even within the setting range (θ = 30 degrees in FIG. 5). The appearance shape is quite different from the smooth bend pipe, and the performance is inferior to the smooth bend pipe. That is, the connection layer 52 that joins the FRP short pipe 51a and the intermediate FRP short pipe 51b arranged at both ends of the curved pipe and the intermediate FRP short pipe 51b is connected to the outer peripheral surface of the curved pipe. Therefore, the connection layer 52 is easily separated or peeled off, and there is a possibility that sufficient watertightness cannot be maintained due to the separation or peeling. Further, since the resistance to the water flow in the curved pipe is large, there is a problem that the pressure loss of the water pressure in the pipe is large and water cannot be efficiently transported.

  On the other hand, FRP curved pipes used for hydraulic power plant hydraulic pipes have a radius of curvature of 3 times or more of the pipe inner diameter by regulations, and the angle of each node in order to minimize the pressure loss of the pipe water pressure. Since the swing is less than 7 degrees, the water transport efficiency is higher than that used for agricultural waterways and sewers. However, compared with the smooth bend pipe, the pressure loss of the pipe water pressure is still large, there is room for improving the water transport efficiency, and there is a possibility that the water tightness may be lowered due to separation or separation of the connection layer.

  Accordingly, an object of the present invention is to provide an FRP bent pipe manufactured by joining a plurality of FRP short pipes with performance comparable to a smooth bend pipe.

  In order to solve the above-described problems, the first invention of the present application is to form a plurality of fiber reinforced plastic short tubes (FRP short tubes) having at least one end surface inclined with respect to the tube axis direction into a curved tube shape. In the fiber reinforced plastic bent pipe (FRP bent pipe) joined in a state where the end faces are butted together, the fiber reinforced plastic short pipe has a random fiber orientation on the outer peripheral surface of each butted portion. A structure in which a cloth body and a reinforcing fiber woven in a cloth shape are joined by resin impregnation to form a laminated body, and the laminated body is formed so as to be continuous with adjacent ones. It was adopted. Here, the FRP bent tube and the FRP short tube include an FRPM bent tube and an FRPM short tube formed by a mortar layer in which the pipe body is sandwiched between the FRP layer and “continuous”. In addition, it is assumed that the laminated body includes a form in which the laminated body partially overlaps with a part adjacent to each other, a form in which end faces are abutted with each other, and a form in which they are integrally formed (the same applies hereinafter).

  That is, according to the first aspect of the present invention, the cloth-like body having a random fiber orientation and suitable for ensuring water-tightness is woven in a cloth shape on the outer peripheral surface of the butt portion of each FRP short tube, and the joint strength is increased. By forming a laminated body obtained by impregnating a reinforcing fiber suitable for the resin with a resin, the FRP short pipe is joined, and the laminated body is formed so as to be continuous with those adjacent to each other. Thus, separation and peeling from the outer peripheral surface of the FRP bent pipe of the laminate were made difficult to maintain sufficient water tightness over a long period of time.

  In the second invention of the present application, a plurality of fiber reinforced plastic short pipes (FRP short pipes) whose at least one end face is inclined with respect to the pipe axis direction are faced to each other so as to be curved. In the fiber reinforced plastic bent pipe (FRP bent pipe) joined together, the inner peripheral surface of the butt portion of each fiber reinforced plastic short pipe is impregnated with a cloth-like body with random fiber orientation and laminated. The configuration in which the laminated body is formed so as to be continuous with those adjacent to each other is adopted.

  In this second invention, laminated bodies obtained by laminating cloth-like bodies having random fiber orientations suitable for ensuring watertightness on the inner peripheral surfaces of the abutting portions of the respective short pipes made of FRP are laminated with each other. By forming it so as to be continuous with the adjacent one, water tightness was improved and resistance to water flow in the pipe was reduced to reduce pressure loss in the pipe water pressure so that water could be transported efficiently. .

  In the first and second inventions, the radius of curvature is at least three times the inner diameter of the tube, and among the short tubes made of fiber reinforced plastic, the two adjacent fiber short tubes made of fiber reinforced plastic are arranged in the tube axis direction. The present invention can be applied particularly effectively to a fiber reinforced plastic bent tube in which the angle formed (the swing of the angle for each node) is 7 degrees or less.

  As described above, the FRP bent pipe of the present invention is formed so that the laminated body is continuous with the adjacent ones on the outer peripheral surface and inner peripheral surface of the butted portion of the FRP short pipe. In addition, in terms of water transport efficiency, it has performance close to that of a smooth bend pipe.

Longitudinal sectional view of FRP curved pipe of embodiment Fig. 1 is an enlarged longitudinal sectional view of the main part of Fig. 1 The longitudinal cross-sectional view which shows the modification of the formation form of a laminated body corresponding to FIG. The longitudinal cross-sectional view which shows another modification of the formation form of a laminated body corresponding to FIG. Vertical section of a conventional FRP curved pipe

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. As shown in FIG. 1, this FRP bent pipe is obtained by joining two types of FRP short pipes 1 (1 a and 1 b) in a state where end faces are butted together so as to form a curved pipe. Because the radius of curvature is more than 3 times the inner diameter of the pipe, the angle formed by the two FRP short pipes 1 adjacent to each other in the pipe axis direction (angle swing for each node) is 7 degrees. It is as follows. Hereinafter, the FRP bent pipe is also simply referred to as “curved pipe”, and the FRP short pipe is also simply referred to as “short pipe”. Further, among the short pipes 1, those arranged at both ends of the curved pipe are referred to as connecting short pipes 1a, and those arranged in the middle portion of the bent pipe, that is, between the connecting short pipes 1a, are referred to as intermediate short pipes 1b. .

  Each of the short pipes 1 is manufactured by cutting a straight pipe made of FRP at the same angle with respect to the pipe axis direction. Among them, only one end surface of the connecting short pipe 1a is inclined with respect to the pipe axis direction, and the other end side is connected to an FRP straight pipe constituting the straight portion of the hydraulic pipe through the connecting pipe (illustration). (Omitted). On the other hand, the intermediate short tube 1b is shorter than the connecting short tube 1a, and both end surfaces are inclined with respect to the tube axis direction, and is joined to the adjacent connecting short tube 1a or the intermediate short tube 1b.

  The short tubes 1 are joined to each other by forming a laminated body 2 containing a resin on the outer peripheral surface of the butted portion in a state where the end surfaces of the short tubes 1 to be joined are butted. Moreover, the laminated body 3 for improving water-tightness is formed in the inner peripheral surface of a butt | matching part so that it may mention later.

  Of the laminates 2 and 3, the laminate 2 formed on the outer peripheral side of the curved pipe is composed of a glass mat that is a cloth-like body with random fiber orientation and a glass cloth that is a reinforcing fiber woven in a cloth shape. And the laminate 3 formed on the inner peripheral side of the curved pipe is obtained by impregnating only a glass mat with resin. An unsaturated polyester resin is used as the resin impregnated into the glass mat and the glass cloth. The arrangement of the glass mat and the glass cloth in the laminated body 2 on the outer periphery side of the curved pipe is arbitrary, but a glass mat suitable for ensuring water-tightness is used for the innermost layer, and the bonding strength is increased for the outermost layer. It is desirable to arrange a suitable glass cloth.

  Each of these laminates 2 and 3 is formed by the following procedure. First, the short tube 1 is butted about 3 nodes, and the outer circumferential surface of the laminated body 2 is formed by laminating and laminating a glass mat and a glass cloth having a size covering each butted portion together on the outer circumferential surface, Thereafter, a glass mat having the same size as that of the outer peripheral side is impregnated on the inner peripheral surface and laminated to form an inner peripheral laminated body 3, and a short tube 1 joined body having about three nodes is formed. To manufacture. After repeating this to produce the required number of joined bodies, the joined bodies are butted together, and the laminated bodies 2 and 3 similar to those at the time of producing the joined body are joined to the outer peripheral surface and inner peripheral surface of the butted portion. It forms so that it may overlap with the laminated bodies 2 and 3 of a body. As shown in FIG. 2, the laminates 2 and 3 formed by this procedure are integrated with ones adjacent to each other, or are partially overlapped and continuous.

  3 and 4 show a modified example of the formation form of the laminates 2 and 3. In the example of FIG. 3, each of the stacked bodies 2 and 3 is formed so as to be continuous with one adjacent to each other. On the other hand, in the example of FIG. 4, each of the stacked bodies 2 and 3 is formed so as to be continuous in a form in which the adjacent end surfaces face each other.

  2 to 4 show an example in which the outer peripheral laminate 2 and the inner peripheral laminate 3 are formed to be continuous in the same form, but the respective laminates 2 and 3 are continuous. As long as it is formed, the form of formation may be different between the outer peripheral side and the inner peripheral side.

  This FRP bent pipe has the above-described configuration, and the outer peripheral side and inner peripheral side laminated bodies 2 and 3 are formed so as to be continuous with those adjacent to each other, so that the external shape is close to a smooth bend pipe, In terms of performance, it is comparable to a smooth bend tube.

  That is, it is difficult for the outer peripheral laminate 2 joining each short tube 1 to be separated from the outer peripheral surface of the curved tube or to be peeled off, and to maintain sufficient watertightness for a long period of time. As a result, the resistance to the water flow in the pipe is reduced, the pressure loss of the pipe water pressure is reduced to the level that occurs in the smooth bend pipe, and as a result, the water transport efficiency equivalent to that of the smooth bend pipe is obtained.

  Here, the outer peripheral laminate 2 is formed by laminating a glass mat and a glass cloth, and the inner peripheral laminate 3 is formed by laminating a glass mat, which improves the water tightness and bonding strength of the curved pipe. Contributing to In addition, the glass mat can be replaced with another cloth-like body having random fiber orientation and suitable for ensuring watertightness, and the glass cloth is woven into a cloth shape and is suitable for increasing the bonding strength. It can be replaced with a reinforcing fiber (roving cloth or the like).

  The present invention can be widely applied not only to FRP bent pipes used for hydraulic pipes of hydroelectric power plants as in the embodiment but also to FRP bent pipes for water transport pipes. Further, as described above, the subject of the invention includes a bent pipe made of FRPM.

1 FRP short pipe 1a Connection short pipe 1b Intermediate short pipe 2 Laminate (outer circumference side)
3 Laminate (inner circumference side)

Claims (3)

In a fiber reinforced plastic curved pipe joined with a plurality of fiber reinforced plastic short pipes whose at least one end face is inclined with respect to the pipe axis direction in a state where the end faces are brought into contact with each other so as to be a curved pipe,
Each of the fiber reinforced plastic short tubes forms a laminated body on the outer peripheral surface of each butt portion by impregnating resin-impregnated cloth-like bodies with random fiber orientations and reinforcing fibers woven in a cloth shape. The laminated body is formed such that a cloth-like body in which the direction of the fibers is random is arranged in the innermost layer and is continuous with the adjacent ones. Reinforced plastic curved pipe. In a fiber reinforced plastic curved pipe joined with a plurality of fiber reinforced plastic short pipes whose at least one end face is inclined with respect to the pipe axis direction in a state where the end faces are brought into contact with each other so as to be a curved pipe,
On the inner peripheral surface of the butt portion of each fiber reinforced plastic short tube, a laminate in which only a cloth-like body with random fiber orientation is impregnated with a resin is laminated so as to be continuous with those adjacent to each other. A fiber-reinforced plastic bent tube characterized by
  The radius of curvature is three times or more of the inner diameter of the tube, and the angle formed by the tube axis directions of two adjacent fiber reinforced plastic short tubes among the fiber reinforced plastic short tubes is 7 degrees or less. The bent pipe made of fiber-reinforced plastic according to claim 1 or 2.

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