JPH0516476Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a fiber-reinforced plastic tube having a threaded portion at the end (hereinafter, fiber-reinforced plastic is referred to as FRP).

[Prior Art] The integral type joint is as shown in FIG. 7, and has a structure in which the female threaded part of an FRP pipe is screwed into the male threaded part of another FRP pipe. There are two types of threaded parts of FRP pipes that have such an integral type joint structure:

FRP pipe reinforced with roving is formed, hardened, and then machined using a diamond tool, grinding wheel, etc. to create female and male threads at both ends.

A female thread is provided by forming an FRP pipe by winding a roving impregnated with uncured synthetic resin around a mandrel with a male thread carved on one end, and a separately molded male thread on the other end.
FRP socket 11 is fitted and bonded with adhesive.

[Problem that the invention attempts to solve] However, in the above case, the conventional threaded part is provided at the end.
Each FRP pipe has the following problems.

In FRP pipes with machined threads on the ends, the rovings are cut off during the thread machining, significantly reducing the strength of the threaded parts.

Threaded parts that have female threads installed during molding of FRP pipes, or glued sockets of molded products with male threads after hardening, have low strength. That is, in the female threaded part, as shown in FIG.
2, the shear strength of the thread is low, and the male threaded portion has a low bonding strength.

In this way, it has a threaded part on the conventional end.
FRP pipes have problems with the strength of their threaded parts, and cannot be applied to applications that require strength, especially against tensile loads.

The present invention solves the problems of the conventional technology described above, and the FRP has a threaded part at the end where the strength of the threaded part is large.
The purpose is to provide pipes.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a fiber-reinforced plastic tube having a threaded portion at the end, the tube body is a synthetic resin layer reinforced with roving, and the threaded portion is made of a synthetic resin layer reinforced with roving. Consists of a synthetic resin layer reinforced with short fibers,
This is a fiber-reinforced plastic tube in which the locking portion of the threaded portion is integrally fixed to the synthetic resin layer of the tube body.

[Function] A resin layer using roving as a reinforcing material has high shear strength and strength against tensile load, but depending on the orientation of the roving, the shear strength and tensile strength become low values. On the other hand, the shear strength of the resin layer reinforced with short fibers is high. The present invention is constructed by combining the two resin layers, and uses the characteristics of each resin layer to compensate for their shortcomings.

Short fibers are randomly oriented in a resin reinforced with short fibers. Therefore, the threaded portion reinforced with short fibers has high shear strength in any direction.

Further, the locking portion provided on the threaded portion is designed so that the roving is locked to the threaded portion when forming the FRP pipe body. Therefore, even if a tensile load is applied, the threaded portion will not come out of the FRP pipe body.

In addition, the short fiber referred to in this invention refers to a single fiber of 1 mm to less than 10 mm, and usually 1 mm to 6 mm.
The preferred length is slightly longer than the height of the screw thread.

[Embodiments of the invention] Hereinafter, embodiments of the invention will be described based on the accompanying drawings.

Fig. 1 is a sectional view showing an FRP pipe with threaded parts at both ends, which is an embodiment of the present invention, and Fig. 2a,
Figure b shows a partial cross-section of an FRP pipe having a threaded portion at the end, Figure a is a partial cross-sectional view of the female threaded part, and Figure b is a partial cross-sectional view of the male threaded part. Further, FIG. 3 is a partially enlarged cross-sectional view of the female threaded portion and the male threaded portion.

In Figure 1, this FRP pipe consists of an FRP pipe main body 1 made of a synthetic resin layer reinforced with rovings, a female threaded part 2 made of a synthetic resin layer reinforced with short fibers, and a synthetic resin layer reinforced with short fibers. It is constituted by a male screw portion 3 made of a resin layer. The female threaded portion 2 and the male threaded portion 3 are formed by casting such as injection molding, and a locking portion is provided on the joint surface with the FRP pipe body 1. and,
This locking portion is fixed integrally with the synthetic resin layer of the FRP pipe main body 1, and is firmly connected to the FRP pipe main body 1.

In FIG. 2, the main body 1 of the FRP pipe has rovings 4 made of high-strength fibers such as glass fibers, carbon fibers, and poamide fibers oriented in a mesh pattern to increase its strength. Further, as shown in FIG. 3, in the female threaded portion 2 or the male threaded portion 3, high-strength short fibers 5 such as glass fibers, carbon fibers, and poamide fibers are randomly oriented.

And FRP of female thread part 2 and male thread part 3
A large number of protrusions 6, which are locking parts, are provided on the surface in contact with the main body 1 of the pipe, and these protrusions 6 are used to lock the roving 4 that is wound to strengthen the main body 1 of the FRP pipe. The threaded portion 3 is designed not to be pulled out from the main body 1 of the FRP pipe.

FIGS. 4a and 4b are diagrams schematically showing the shapes of the female threaded portion and the male threaded portion; FIG. 4a is a diagram showing the female threaded portion, and FIG. 4b is a diagram showing the male threaded portion. In Fig. 4a, the female thread part is a short pipe with a female thread,
A protrusion 6 is formed on the outside thereof, and this protrusion 6
are arranged in accordance with the winding angle α of the roving to ensure that the roving is locked. In figure b, the male threaded part is a short tube with a male thread on one side, and a protrusion 6 on the outside of the other side.
is formed. The arrangement of the protrusions 6 is matched to the winding angle α of the roving, similarly to the female threaded portion.

FIGS. 5a and 5b are views showing other embodiments of locking portions formed on the female threaded portion and the male threaded portion. Fifth
In figures a and b, figure a shows the female threaded part,
Figure b shows the male threaded part, and the outside of the female threaded part and the male threaded part has the winding angle α of the roving.
Accordingly, a large number of grooves 7 serving as locking portions are formed in a mesh shape, and these grooves 7 are connected to the protrusions 6 in FIGS. 4a and 4b.
Lock the roving in the same way.

Next, a method of manufacturing an FRP pipe having a threaded portion at the end according to the present invention will be explained with reference to FIG. The female threaded part 2 and the male threaded part 3, which have been formed in advance in a separate process, are inserted into both ends of the mandrel 10, and a roving impregnated with an uncured thermosetting resin is wound around them using the filament winding method. A roving reinforced resin layer, that is, an FRP pipe body is formed. After heating and curing this molded product, the mandrel is removed to obtain a product. When the resin hardens in this step, the female threaded portion 2 and the male threaded portion 3 are firmly fixed and integrated with the main body of the FRP pipe.

[Effects of the invention] The FRP pipe with a threaded end at the end of the invention has a high shear strength because the threaded part is made of a synthetic resin layer reinforced with short fibers. A locking part is provided on the surface of the threaded part that contacts the main body of the FRP pipe to increase the strength against tensile loads.
The joint with the main body of the pipe is not adhesive, but is firmly fixed and formed as an integral part when the main body of the FRP pipe hardens, so the tensile strength of the joint (joint efficiency) is significantly improved.

In addition, the female threaded part and the male threaded part are molded in separate processes and are fixed and integrated when the main body of the FRP pipe is molded, so there is no need for threading.
Easy to manufacture.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view showing an FRP pipe with threaded sections at both ends, which is an embodiment of the present invention, Figures 2 a and b are partial cross-sectional views of the female threaded part and the male threaded part, and Figure 3 is the female threaded part. A partially enlarged sectional view showing the threaded part and the male threaded part,
Figures 4a and b are diagrams schematically showing the shapes of the female threaded part and the male threaded part, and Figures 5a and b are diagrams showing other embodiments of the locking parts formed on the female threaded part and the male threaded part. The illustrated diagram, Figure 6, is an explanatory diagram of a method for manufacturing an FRP pipe with threaded parts at both ends, which is an embodiment of the present invention, and Figure 7.
The figure shows a joint of FRP pipes with a conventional threaded end, and Figure 8 shows a joint with a conventional threaded end.
FIG. 3 is a diagram showing a cross section of a threaded portion of an FRP pipe. 1...Main body of FRP pipe, 2...Female thread part, 3...
...Male thread part, 4...Roving, 5...Short fiber,
6...Protrusion, 7...Groove.

Claims (1)

[Scope of utility model registration request] A fiber-reinforced plastic tube with a threaded end, the tube body is made of a synthetic resin layer reinforced with roving,
A fiber-reinforced plastic tube, characterized in that the threaded portion is made of a synthetic resin layer reinforced with short fibers, and a locking portion of the threaded portion is fixed integrally with the synthetic resin layer of the tube body.