JPS5935327B2 - Manufacturing method of reinforced plastic tube - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing reinforced plastic pipes using a filament winding method, but the method for manufacturing reinforced plastic pipes according to the present invention is equally applicable to single-layer pipes and composite pipes. The method detailed below is mainly explained when applied to a typical composite pipe, but the application of the present invention is not limited to composite pipes, but can also be applied to single-layer pipes. Needless to say, it is possible.

In addition, the conventional manufacturing method of reinforced plastic pipes, for example ■■■■
■■■Mi■■■■■■■■■■■■■ Any method in which a single core mold is rotated and layered while sequentially moving in the axial direction or lateral direction of the core mold is the manufacturing method of the present invention. available for use.

A typical structure of composite reinforced plastic pipes is that the inner and outer layers are made of relatively thin layers made of glass fiber impregnated with a thermosetting resin, and the mortar layer is made of granular materials such as silica sand bonded with a binder in the middle of the inner and outer layers. Composite pipes with interposed

The reinforced plastic pipe with the above structure has excellent corrosion resistance and light weight, and can withstand internal and external pressure, so it is attracting attention as an alternative to concrete pipes and metal pipes, and has a wide range of uses and extremely high utility value. Various methods for manufacturing such reinforced plastic tubes are known, and a typical one is the filament winding method. In this method, first, long resin-impregnated glass fibers or carbon fibers (hereinafter referred to as transverse threads) are wound around a rotating core bar in the circumferential direction. As it is, the bending moment and tensile strength in the axial direction of the pipe are weak, so in order to increase this, a method has been used in which short lengths of glass fiber or carbon fiber (hereinafter referred to as longitudinal reinforcement) are arranged in a direction that intersects with the horizontal reinforcement. There is. As a general method for arranging vertical reinforcements, a method is widely known in which the vertical reinforcements are placed on top of the running horizontal reinforcements under tension, and then the horizontal reinforcements are wound at the same time as the horizontal reinforcements are wound (see FIG. 1). This completes the single-layer pipe, but in the case of composite reinforced plastic pipes, a layer of mortar made of silica sand bound with a binder is wrapped around the inner layer constructed in this way in the form of a band, or a layer of mortar is wrapped inside the mold. An intermediate layer is formed by filling and coating the outer surface of the inner layer tube placed in the tube with the mortar, and finally an outer layer is wrapped and heat treated in the same manner as the inner layer. In such conventional methods, the strength of reinforced plastic pipes is greatly influenced by the skill of arranging the glass fibers and carbon fibers wound in the inner and outer layers, and large variations in the strength of the manufactured pipes are unavoidable. Ta. For this purpose, many methods for arranging vertical stripes other than those described above have been proposed, but none of them have been satisfactory. For example, for glass fibers that serve as horizontal stripes, vertical strips are knitted in advance into a strip shape and connected to a strip, and this is then wrapped around a core metal. Methods such as insertion have been proposed, but in these cases the cost is high and moreover, more resin than necessary adheres to the stitches, so they are not desirable from an economical point of view. Therefore, in the end, the method according to the method shown in FIG. 1 described above had no choice but to become mainstream.

FIG. 1 is a schematic plan view showing an example of a conventional method for manufacturing reinforced plastic tubes, and shows an example in which a so-called Dorstholm machine is used. FIG. 2 shows a cross-sectional view of a main part of a reinforced plastic tube obtained by the filament winding method shown in FIG. It is a schematic explanatory view showing a winding method. The vertical reinforcement 3 is placed on the horizontal reinforcement 2 and supplied from the vertical reinforcement supply device 8. It is advantageous to have a vertical fiber supplying device 8 of a natural fall type or a forced fall type using air, which cuts the long fibers with an appropriate cutting device to provide the vertical fibers. The horizontal stripes 2 constituting the inner layer A are immersed in a solution of thermosetting resin 6 while running in the direction of the arrow, and further run in a state impregnated with an appropriate amount of thermosetting resin 6. Next, the vertical reinforcement 3 supplied from the vertical reinforcement supply device 8 is dropped and transferred onto the upper surface of the horizontal reinforcement 2, and finally wrapped around the core metal 5 to form the inner layer A. For the intermediate layer B, a mixture of silica sand and a binder is formed into a sheet-like mortar 4 (FIG. 1), and the sheet-like mortar 4 is continuously wound on the inner layer along the rotation of the core bar 5. It is formed by The outer layer C is formed by the same or similar method as the inner layer A, and the outer layer C is formed by further wrapping the horizontal strips 2 and the vertical strips 3 on the mortar 4 of the intermediate layer B. Various factors can be considered to affect the strength of such composite reinforced plastic pipes, but in particular, the resin layer (inner layer A1 outer layer C) has horizontal stripes 2 and vertical strips 3.
and the bonding properties of the thermosetting resin 6 are important factors.
That is, since the transverse reinforcement wound in the circumferential direction is a long filament, sufficient tension can be applied, and a strong tensile force acts on the external force in the direction perpendicular to the tube axis. However, since the longitudinal reinforcements 3 arranged in the axial direction are simply tightened by the horizontal reinforcements 2, sufficient tension is not applied. Therefore, in order to make a reinforced plastic pipe that has sufficient strength against the bending moment of the pipe and can withstand the tension applied in the axial direction, when the horizontal reinforcement 2 is wound spirally, the vertical reinforcement must gradually wrap around each other. It is desirable to wrap it in a similar manner. In order to do this, it was necessary to use short fibers slightly longer than the width of the long fiber band as the vertical strips 3 so that the ends of these strips were intertwined with each other. However, according to this method, as can be inferred from FIG. 1, only one end of the vertical strip is wrapped, and the expected strength improvement cannot be obtained. Of course, as shown in FIG. 2, the inner layer A receives the tightening force from the intermediate layer B, so that a certain degree of strength is obtained, but it cannot be said that sufficient strength is obtained due to entanglement. This also applies to the outer layer C, and in this case, since there is no tightening with mortar, etc., the ends 3' of the vertical strips 3, which are longer than the pitches of the spiral winding, are exposed as whiskers from the tube wall. However, it should be said that an increase in strength due to the actual lapping can be expected. In addition, since the longitudinal stripes in the resin layer have a wavy shape, air bubbles 10 are likely to be generated between the thermosetting resin and each fiber.
As a result, not only is the bond between the resin and the fibers weak;
Another problem is that it is difficult to use as a high-pressure pipe because it may cause water leakage. The present invention was made in view of the above circumstances, and its purpose is to create a reinforced plastic tube that can sufficiently increase its strength against bending moments by ideally arranging vertical bars. The purpose of this invention is to provide a method for manufacturing.

The structure of the manufacturing method according to the present invention that can achieve the above object is that the fibers of the transverse stripes are arranged in a medium-thickness fiber band that becomes denser from both sides toward the center, and when wrapped, The gist is that the primary winding is performed in a gap having a width smaller than the width of the thick fibrous band, and then the medium-thick fibrous band is wrapped again so as to fill the gap. As a result, the vertical bars overlap each other at both ends to maintain strength in the axial direction, and do not protrude from the horizontal bars. In addition, the degree of bonding between the medium-thickness fiber band, the short fiber for longitudinal reinforcement, and the thermosetting resin is significantly improved, and air bubbles are not generated in the inner layer and/or the outer layer, resulting in excellent strength and watertightness. Summer. In addition, the length of the short fibers for the longitudinal strips can be shorter than the pitch of the long fiber band, and it is easy to align the short fibers for the longitudinal strips in parallel and at equal intervals. As a result, it was possible to obtain a reinforced plastic tube in which the reinforcing efficiency of the longitudinal reinforcing fibers was significantly improved. The configuration and effects of the present invention will be explained below based on the drawings which are examples, but it goes without saying that the following explanations relate to typical examples of the present invention and are not intended to limit the present invention.

FIG. 4 is a perspective view of a long filament according to the present invention, in which the transverse striations 2 are arranged to have a substantially constant width to form a filament band, and the filament band is arranged in such a way that the filaments are arranged from both sides toward the center. The medium-thickness fiber bands 2a are shown arranged densely, and the medium-thickness fiber bands 2a are impregnated with a thermosetting resin and transferred with longitudinal strips 3 in the same manner as explained in FIG. It will be done. FIG. 5 is a schematic explanatory diagram showing one embodiment of a method for manufacturing a composite reinforced plastic tube by the filament winding method using such a medium-thickness filament band 2a, and FIG. A sectional view of a main part of a reinforced plastic tube obtained using the thick fiber strip 2a is shown. That is, in the method of the present invention, the medium-thickness filament band 2a is spirally formed so as to form a gap T2 having a width smaller than the width t1 of the medium-thickness filament band 2a on the axial surface of the rotating core bar 5. Perform primary winding. Next, the medium-thick fiber band 2b is wound spirally so as to fill the gap T2. Therefore, both ends 12' of the medium-thickness fibrous band 2b are wrapped so as to wrap around each end 12 (FIG. 6) of the medium-thickness fibrous band 2a which has been primarily wound. In this way, first, the inner layer A' is spirally wound along the circumference of the core metal 5, then the mortar 4 is spirally wound in the same manner as before to form the intermediate layer B2, and the outer layer c' is formed in the same manner as the inner layer N. Perform spiral winding according to the procedure. It should be noted that although the above explanation was mainly given in the case of a composite pipe, it goes without saying that it can be similarly applied to a single-layer pipe. Since the present invention is carried out in this manner, the medium-thickness filament bands 2a, 2b are wrapped around each other.

Therefore, as shown in the inner layer A and the outer layer C2, the medium thickness filament band 2a
, 2b correspond to each other and overlap to form an inner layer A and an outer layer c' of constant thickness. Furthermore, since the lap area of the medium-thickness fiber bands 2a, 2a' is wider than that of the conventional example, the binding force in the axial direction is excellent, and an unprecedented strength can be exhibited. Further, since the medium-thickness filament band 2a, which is the transverse strip, is formed into a band shape, the transverse fibers are bound together within the medium-thickness filament band 2a, resulting in even better strength. Furthermore, according to the present invention, the generation of air bubbles at the bonding surface between each fiber and the thermosetting resin is eliminated, and the longitudinal fibers can be made shorter than the width of the medium-thickness fiber band, so that they are not exposed from the tube wall. This eliminates the stubble that had been associated with the process, making it possible to obtain a reinforced plastic tube that is stronger in both the circumferential and axial directions. Since the present invention is constructed as described above, by using medium-thickness fiber bands as the transverse reinforcement, the reinforcement efficiency of the short longitudinal fibers is significantly improved, and the reinforced plastic tube is made even stronger. Furthermore, since there is no water leakage, the industrial value has further increased.

[Brief explanation of the drawing]

The drawings are for explaining the present invention, and FIG. 1 is a schematic diagram showing a conventional method for manufacturing reinforced plastic pipes, FIG. 2 is a cross-sectional view of the main part of FIG. 1, FIG. 3 is a schematic explanatory diagram, and FIG. 4 5 is a schematic explanatory view corresponding to FIG. 1, and FIG. 6 is a sectional view of a main part corresponding to FIG. 2. 1... Reinforced plastic tube, 2... Horizontal stripes, 3... Vertical stripes, 6... Thermosetting resin, A... Inner layer , B...middle class, C...
...outer layer, 2a...medium-thick filamentous band.

Claims (1)

[Claims] 1. In forming a reinforced plastic tube, a large number of long fibers are arranged to have a substantially constant width to form a fiber band, and the fiber band is impregnated with a thermosetting resin, and the surface thereof is coated with the above-mentioned material. In a method of manufacturing a reinforced plastic tube by arranging short longitudinal fibers so as to intersect with long fibers and winding the fiber band in an annular shape, the fiber band has a structure in which the fiber arrangement is changed from both sides. Medium-thickness fiber bands are arranged densely as they reach the center, and during winding, primary winding is performed with a gap smaller in width than the width of the medium-thickness fiber band, and then the first winding is performed again to fill the gap. A method for manufacturing a reinforced plastic tube characterized by wrapping a medium-thickness filament band around it.