JP3014402B2 - Fiber reinforced plastic pipe and method for producing the same - Google Patents

Description

The present invention relates to a fiber-reinforced plastic pipe and a method for producing the same, which can be suitably used for, for example, a winding core of photographic film, photographic paper, and various rolls. About.

(Problems to be Solved by the Prior Art and the Invention) As a method of manufacturing a fiber reinforced plastic pipe, a reinforcing fiber bundle impregnated with a thermosetting resin is wound around a mandrel by operating a traverse, and then heated and cured to release the mold. There is a filament winding method. By the way, even pipes formed by this filament winding method became heavy, weighing over 300 kg, and were difficult to handle.

The present invention has been made in view of such conventional problems, and has as its object to reduce the weight within a range that does not affect the strength, and to manufacture a fiber-reinforced plastic pipe. There is a way to provide.

(Means for Solving the Problems) Accordingly, a fiber-reinforced plastic pipe according to the present invention has the following configuration to achieve the above object. That is, in the fiber reinforced plastic pipe formed by the filament winding method, the thickness of the intermediate portion excluding both side portions is reduced by forming a stepped concave portion on the inner surface side.

As a method for manufacturing such a fiber-reinforced plastic pipe, there is the following method. That is, in a method for producing a fiber-reinforced plastic pipe by a filament winding method, a part of the outer periphery of a mandrel is covered with a thermoplastic foam. Then, a reinforcing fiber bundle impregnated with a thermosetting resin is wound around the outer circumference of the mandrel including the portion covering the foam to form a fiber layer. Thereafter, by heating, the fiber layer is cured and the foam is dissolved and gasified, and then the mold is released.

(Embodiment) An embodiment of the present invention will be described below with reference to FIGS. In the figure, reference numeral 1 denotes a mandrel which is rotated by a shaft 2 and the outer periphery of an intermediate portion excluding both sides thereof is covered with a thermoplastic foam 3 which is attached by appropriate means. The thermoplastic foam 3 is selected to be dissolved and gasified at a predetermined temperature in relation to a thermosetting resin impregnated into a reinforcing fiber bundle described later. In this example, a foam that melts and gasifies within a temperature range of 120C to 180C is selected.

As evident in FIG. 3, this thermoplastic foam 3
It is formed in a half-split shape to form a pair of cylinders.
One or more sheets may constitute a cylinder, and of course, a cylinder may be integrally formed. Also, both ends 4 of the thermoplastic foam 3 are:
It has a gentle slope so that it does not affect the winding of the reinforcing fiber bundle.
Angle of inclination within.

In this manner, the intermediate portion of the mandrel 1 is covered with the thermoplastic foam 3, and the outer periphery of the mandrel 1 including the covered portion is impregnated with a thermosetting resin, and the reinforcing fiber bundle is impregnated with the filament winding method. To form a fiber layer 5 (5a, 5b).

The reinforcing fiber bundle is composed of continuous fibers made of a suitable reinforcing material such as glass fiber, carbon fiber, and boron fiber.The thermosetting resin impregnated in the fiber bundle is, for example, an epoxy resin. You. A conductive material such as carbon may be mixed into the thermosetting resin to perform a process for preventing static electricity from being charged.

In order to maintain the strength of the pipe, the reinforcing fiber bundle needs to be continuously wound without being cut, and the fiber layer 5 (5a, 5b) formed by the continuous winding is required. Requires that the surface be formed flush. That is, the first fiber layer 5 which is a portion covering the foam 3
(5a) surface and second fiber layer 5 as uncovered portion
It is necessary to wind the reinforcing fiber bundle so that a step is not formed between the reinforcing fiber bundle and the surface of (5b).

In FIG. 2, Level L indicates the first layer in which the entire peripheral surface of the foam 3 is completely filled with the reinforcing fiber bundle. This first fiber layer 5
The step does not occur if the thickness A of the foam 3 is further filled in the second fiber layer 5 (5b) during molding of one layer of (5a). Such a wrap is mandrel 1
It is possible by changing the winding angle of the reinforcing fiber bundle with respect to the axis of the first fiber layer 5 (5a) and the second fiber layer 5 (5b). While the first fiber layer 5 (5a) is formed as one layer, the number of layers of the second fiber layer 5 (5b) formed so that the two levels match each other depends on the outer diameter of the mandrel 1 and the reinforcement. It is determined by the roving band width of the fiber bundle and the winding angle of the reinforcing fiber bundle in the first and second fiber layers 5 (5a, 5b). Of course, the first fiber layer 5 (5a)
Can be wound so that the levels of both fiber layers 5 (5a, 5b) match.

After reaching the level L, the first fiber layer 5 (5a) and the second fiber layer 5 (5b) are both formed at the same winding angle. However, for winding after level L,
A unit layer having the same winding angle may be set, and the winding angle may be appropriately changed for each unit layer, and the unit layers may be wound.

When the winding of the reinforcing fiber bundle is completed by such a winding method, the bundle is transferred to a curing furnace and heated. First, the mandrel 1 and the fiber layers 5 (5a, 5b) wound around the mandrel 1 can be uniformly heated.
Preheat at 100 ° C for about 2 hours. After preheating, 120
C. and heat for about 2 hours. The thermosetting resin (epoxy resin) impregnated in the reinforcing fiber bundle is cured. In order to increase the strength, the heating temperature is raised to 160-180 ° C and additional heating is performed for about 4 hours. As the fiber layer hardens to a high degree,
The thermoplastic foam 3 melts and gasifies. Thereafter, the mandrel 1 is removed so as to be pulled out. The portion where the foam 3 is dissolved becomes a void, and the fiber layer 5 and the mandrel 1 are not in contact with each other. A stepped concave portion 6 corresponding to the volume of the melted foam 3 is formed on the inner surface side of the intermediate portion of the removed pipe, so that the thickness is reduced and the weight is reduced.

In this embodiment, an epoxy resin is used as a thermosetting resin to be impregnated into the reinforcing fiber bundle, and a thermoplastic foam 3 which is attached to the mandrel 1 is melted and gasified in a temperature range of 120 ° C. to 180 ° C. The body was selected, but is not intended to be limited to these materials. At first, like the combination of the epoxy resin and the thermoplastic foam 3, in the predetermined temperature range (120 ° C. to 180 ° C. in the example), the former is cured first, and after the curing, the latter is dissolved and gasified. A relationship is needed. That is, in the course of the heat treatment in the curing furnace, the two are required to have such a relationship that the thermoplastic foam 3 does not thermally deform until the thermosetting resin is cured, but is dissolved and gasified after the curing.

After removal from the mold, finishing processes such as cutting, painting, and polishing are performed.

Next, FIG. 4 shows an example of a multi-cavity in which one mandrel 1 is used to form two pipes. That is,
A thermoplastic foam 3 is provided on the outer periphery of the left and right sides of the mandrel 1.
To each. Thereafter, the reinforcing fiber bundle impregnated with the thermosetting resin is wound by the same winding method as in the above-described embodiment. After heat curing, the mold is removed, and the mold is divided vertically into two equal parts from the center. As is apparent from this embodiment, two or more pipes can be formed by filament winding using one mandrel 1. The point that a stepped recess is formed on the inner surface of the intermediate portion of each formed pipe is exactly the same as that of the pipe of the above embodiment.

(Effects of the Invention) As is apparent from the detailed description above, the fiber-reinforced plastic pipe of the present invention has a stepped recess formed on the inner surface side of the intermediate portion thereof and has a reduced thickness, so that the weight of the entire pipe is reduced. However, it is lightweight and easy to carry and other handling. Since the wall thickness is not reduced on both sides of the pipe to which the load is applied, the strength of the pipe is not affected.

Further, according to the production method of the present invention, a fiber-reinforced plastic pipe having a stepped concave portion on the inner surface side of the intermediate portion can be easily obtained with a simple configuration in which a part of the outer periphery of the mandrel is covered with a thermoplastic foam. . In addition, according to this manufacturing method, the portion covered with the thermoplastic foam forms a gap between the mandrel and the fiber layer due to the dissolution of the foam, so that the pull-out resistance of the mandrel during demolding is reduced. This also has the effect of reducing the number of molds and facilitating the removal work.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the manufacturing method of the present invention,
FIG. 2 is an enlarged sectional view of a main part thereof, FIG. 3 is an exploded perspective view of a state in which a thermoplastic foam is attached to a mandrel, and FIG. 4 is an exploded perspective view of another state in which a thermoplastic foam is attached to a mandrel. It is. 1 ... mandrel, 3 ... thermoplastic foam 5 (5a, 5b) ... fiber layer 6 ... step recess

Claims (2)

(57) [Claims] 1. A fiber reinforced plastic pipe formed by a filament winding method, wherein an intermediate portion excluding both side portions is reduced in thickness by forming a stepped recess on an inner surface side. pipe. 2. A method of manufacturing a fiber-reinforced plastic pipe by a filament winding method, wherein a part of the outer periphery of a mandrel is covered with a thermoplastic foam, and the outer periphery of the mandrel including a portion covering the foam is thermoset. Winding a reinforcing fiber bundle impregnated with a conductive resin to form a fiber layer, and then heating to cure the fiber layer and dissolve and gasify the foam,
A method for producing a fiber-reinforced plastic pipe, which is then demolded.