JPH08127064A - Screwed fiber reinforced thermoplastic resin composite pipe and production thereof - Google Patents

Abstract

PURPOSE: To facilitate the connection work to a joint, to enhance the reliability of connection strength and to prevent not only the generation of a cut powder at the time of the formation of a screw part but also the reduction of fiber reinforcing effect. CONSTITUTION: A fiber reinforced thermoplastic resin composite pipe 15 is obtained by laminating and welding a thermoplastic resin inner layer 2, a first reinforcing layer 3 composed of a thermoplastic resin containing a continuous reinforcing fiber oriented in a pipe axial direction, a second reinforcing layer 4 composed of a thermoplastic resin containing a continuous reinforcing fiber spirally oriented in a pipe axial direction and a thermoplastic resin outer layer 5 and screw parts 14 are formed to both end parts of the thermoplastic resin outer layer 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a threaded fiber reinforced thermoplastic resin composite pipe and a method for producing the same.

[0002]

2. Description of the Related Art Fiber-reinforced thermoplastic resin composite pipes are widely used as piping members because they are lighter in weight than metal pipes, do not rust, and have higher strength than synthetic resin pipes.
When connecting the fiber-reinforced thermoplastic resin composite pipe to the pipe joint during pipe construction, an adhesive was applied to at least the end of the former to bond them to each other.

However, the connection between the pipe and the pipe joint by the adhesive is not only troublesome, but the workability may be deteriorated by the solvent in the adhesive, and in the case of the fiber-reinforced composite pipe, the reinforcing fiber is usually used. Since it was raised on the surface of the pipe and the surface smoothness was poor, the connection strength was particularly poor as compared with the case of the synthetic resin pipe. Further, if the fiber-reinforced thermoplastic resin pipe and the pipe joint are once adhered and connected, there is a problem that the joint cannot be released and removed at the time of member replacement or repair.

In order to solve the above-mentioned problems, it has been proposed that the inner surface or the outer surface of the end portion of the fiber reinforced thermoplastic resin pipe is cut to form a screw thread, and the screw portion is provided (Japanese Patent Laid-Open No. HEI 5). No. 126119).

However, when the threads are formed by cutting, not only does the environment worsen by the generation of cutting chips in which the thermoplastic resin and the reinforcing fibers are mixed, but the reinforcing fibers are exposed on the surface of the threaded portion. The tightening of the screw to the screw may be incomplete, and the reinforcing fiber will be cut together with the thermoplastic resin during the cutting process, so the reinforcing effect of the fiber of the screw part will be reduced, causing the breakage or cracking of the pipe. Becomes

[0006]

DISCLOSURE OF THE INVENTION The present invention provides a threaded fiber which facilitates connection work to a joint, improves reliability of connection strength, and does not generate cutting chips when forming a threaded portion and does not reduce fiber reinforcing effect. To provide a reinforced thermoplastic resin composite pipe and a method for manufacturing the same.

[0007]

According to a first aspect of the present invention, there is provided a threaded fiber reinforced thermoplastic resin composite tube, wherein a thermoplastic resin outer layer is provided on at least an outer surface side of an outer surface and an inner surface of the fiber reinforced thermoplastic resin composite tube. The threaded portion is provided on the outer layer of at least one end of both ends of the composite pipe.

According to a second aspect of the present invention, there is provided a method for producing a fiber-reinforced thermoplastic resin composite pipe with a thread, wherein a thermoplastic resin outer layer is provided on at least an outer surface side of an outer surface and an inner surface of the fiber-reinforced thermoplastic resin composite tube. The outer layer of at least one of the both ends is heated to soften the thermoplastic resin, and then the outer layer end is pressed by a split mold for screw molding to form a screw part at the same end. It is a thing.

Specific examples of the thermoplastic resin include, for example,
Examples thereof include polyvinyl chloride, chlorinated polyvinyl chloride, polyethylene, polypropylene, polystyrene, polyamide, polycarbonate, polyphenylene sulfide, polysulfone, and polyether ether ketone, which are appropriately selected depending on the use of the pipe.

The thermoplastic resins may be used alone or in combination. When they are used in combination, they must be compatible with each other in order to prevent the strength of the fiber-reinforced thermoplastic resin composite pipe from being lowered. is there.

If necessary, a heat stabilizer, a plasticizer, a lubricant, an antioxidant, an ultraviolet absorber, a colorant, an inorganic filler, etc. may be added to the thermoplastic resin.

Although the thermoplastic resin outer layer may be provided only on the outer surface side of the fiber-reinforced thermoplastic resin composite tube, the thermoplastic resin inner layer may be provided on the inner surface side as well. The thermoplastic resin and the thermoplastic resin of the reinforcing layer are preferably a combination with good fusion properties in terms of suppressing delamination.
It is particularly preferable to use the same thermoplastic resin. Further, a plurality of reinforcing layers may be present, and in some cases, an adhesive layer may be interposed between the respective layers.

Specific examples of the reinforcing fibers of the reinforcing layer include inorganic fibers such as glass fibers and carbon fibers; organic fibers such as aramid, vinylon and polyester. These may be used alone or in combination. May be.

The reinforcing fibers may be in the form of monofilament-like, roving-like, strand-like, mat-like continuous fibers such as swirl mat, or cross-like, net-like or net-like fibers having continuous fibers in the longitudinal direction, or continuous. Not only the fibers but also mat-like or non-woven fabrics may be used together, and the short fibers may be randomly arranged together with the continuous fibers.

The method for producing the fiber-reinforced thermoplastic resin tube before forming the threaded portion is not particularly limited. For example, a layer of a thermoplastic resin containing continuous reinforcing fibers may be laminated on the thermoplastic resin tube as an inner layer. The tape-shaped or string-shaped fiber composite in which the thermoplastic resin is held on the continuous reinforcing fibers is spirally wound, and then the thermoplastic resin of the outer layer is laminated to manufacture. The inner and outer thermoplastic resin layers are usually formed by extrusion molding in terms of production efficiency, but are not limited thereto. As a method for producing a fiber-reinforced thermoplastic resin composite pipe, which is obtained by laminating and laminating three layers of an inner layer thermoplastic resin layer, a thermoplastic resin reinforcing layer containing continuous reinforcing fibers, and an outer layer thermoplastic resin layer, Japanese Patent Laid-Open No. 165930/1990, Japanese Patent Laid-Open No. 3-1
The methods described in JP-A-57591 and JP-A-4-201548 are preferable in terms of production efficiency.

The threaded portion is a male thread since it is formed in the outer layer, and its shape is not particularly limited. However, when it is used for piping, it is necessary that the gas and liquid flowing inside the tube do not leak. The shape of the B 0203 tapered thread for pipes is most preferred. However, the present invention is not limited to this, and parallel threads may be used depending on the application.

Since the threaded portion is formed in the outer layer, the thermoplastic resin in the outer layer at least at the pipe end must be softened at this time, but the thermoplastic resins in the other layers do not necessarily have to be in a softened state. The resin temperature for softening the outer layer thermoplastic resin is
The temperature may be a flowable state, and although it depends on the applied pressure, it is preferable to appropriately select it in accordance with the molding state from a range not lower than the Vicat softening point temperature of the outer layer thermoplastic resin and not higher than the melting point and not thermally decomposed. .

The method for heating the thermoplastic resin is not particularly limited, but may be heated with a hot air blower, infrared rays, fire or the like, or may be pressurized using a heated split mold for screw molding. Further, the pressing force is 3 to 200 kg / cm ² , preferably 5 to 100 kg / cm ² , and more preferably 10 to 50 kg /, though it varies depending on the type of resin and the flow state of the softened resin at the time of pressurization. cm ² .

The pipe joint used when piping the threaded fiber-reinforced thermoplastic resin pipe is not particularly limited as long as it has an internal thread on its inner surface. The shape is also appropriately selected depending on the application, such as socket, elbow, cheese, and union. When the pipe joint is made of synthetic resin, it is generally injection-molded.

In order to improve the sealing property during piping, it is effective to wrap the thread part with a sealing tape having Teflon property or to apply a sealing agent such as liquid or paste to connect with the joint. Target.

[0021]

In the fiber-reinforced thermoplastic resin composite pipe with a thread according to the first aspect of the present invention, a thermoplastic resin outer layer is provided on at least the outer surface side of the outer surface and the inner surface of the fiber-reinforced thermoplastic resin composite tube. Since the threaded portion is provided on the outer layer of at least one of the both ends, it is sufficient to screw this composite pipe to the female threaded pipe joint at the time of piping work, and the reinforcing fiber is exposed on the threaded surface. I have never done it.

According to a second aspect of the present invention, there is provided a method for producing a fiber-reinforced thermoplastic resin composite pipe with a thread, in which a thermoplastic resin outer layer is provided on at least the outer surface side of the outer surface and the inner surface of the fiber-reinforced thermoplastic resin composite tube. After heating the outer layer of at least one of the two ends of the tube to soften the thermoplastic resin, the end of the outer layer is pressed with a split mold for screw molding to form a thread at the same end. Unlike forming a screw thread by cutting, no cutting chips are generated, and since only the thermoplastic resin outer layer forms a screw portion, there is no risk of the fibers of the reinforcing layer being cut.

[0023]

Embodiments of the present invention will be described below with reference to the drawings. Example 1 First, an inner diameter of 25 mm, an outer diameter of 32 mm, and a length of 1 shown in FIG.
1. Prepare a fiber-reinforced thermoplastic resin composite pipe (1) of m. This fiber reinforced thermoplastic resin composite pipe (1) has a thermoplastic resin inner layer
(2) a thermoplastic resin first reinforcing layer (3) containing continuous reinforcing fibers oriented in the pipe axis direction, a thermoplastic resin second reinforcing layer (4) containing continuous reinforcing fibers oriented in the pipe circumferential direction, and heat The outer layer of plastic resin (5) is laminated and fused, and each layer (2)
The thickness of (5) is 1 mm, 0.5 mm, 0.5 mm and 1.5 mm. The thermoplastic resin is vinyl chloride resin (polymerization degree 700) and the reinforcing fiber is glass fiber (diameter). 23 μm), and is manufactured by the method described in JP-A-3-157591.

One end of the fiber-reinforced thermoplastic resin composite tube (1) was heated by a hot air generator until the temperature of the thermoplastic resin of the outer layer (5) reached 180 ° C. Next, the outer layer (5)
The thread forming device (6) shown in Fig. 2 is used to form the threaded portion at the end of the thread forming device (6). This thread forming device (6) has one end and the inside diameter of the fiber-reinforced thermoplastic resin composite pipe (1). A cylindrical main body (8) having a horizontal core (7) having a substantially equal outer diameter and having an outer diameter within the thickness of the outer layer (5), and a male screw portion (9a) provided above and below the main body (8). A bar-shaped protrusion (9) with a core (7)
And tapered taper female thread (10a) (JISB 0203
Has the same shape as the female screw of PT1) and has a base (10
The base of each bar-shaped protrusion (9) by the hole (11) drilled in b).
Split mold with a semicircular cross section that can be moved up and down in (9b) and is kept at a predetermined distance from the main body (8)
(10) and a nut (13) screwed to the male screw portion (9a) of the rod-shaped protrusion (9) via the annular spacer (12).

Fit one end of the fiber-reinforced thermoplastic resin composite pipe (1) to the core (7) of the screw forming device (6), then tighten the nut (13) and screw each split mold (10). Move inward,
When one end of the thermoplastic resin outer layer (5) softened by heating was pressed at 30 kg / cm ² for 1 minute, a taper screw portion (14) as shown in FIG. 3 was formed. After forming the screw part (14), in order to ensure its dimensional accuracy, after cooling sufficiently, remove it from the screw forming device (6), and similarly form the screw part (14) on the other end as well. A fiber reinforced thermoplastic resin composite pipe (15) with a thread was obtained.

The core (7) is a fiber-reinforced thermoplastic resin composite tube.
This is to prevent inward deformation when pressing one end of (1) with a split mold. The split mold (10) has 2
However, depending on the pipe diameter, three or more may be used. In this case, the number of rod-shaped protrusions (9) having male threads (9a), spacers (12) and nuts (13) , Split type (10)
It is possible to correspond to the number of.

Example 2 Polyethylene was used as the thermoplastic resin of the fiber-reinforced thermoplastic resin composite pipe, and the heating temperature of the outer layer of the composite pipe was 17
Fiber reinforced thermoplastic resin with both ends screwed in the same manner as in Example 1 except that the temperature was 0 ° C., the pressure applied to the split mold was 20 kg / cm ^2, and the screw part described in JIS B 0203 was formed. A composite tube was obtained.

Comparative Example 1 A fiber reinforced thermoplastic resin composite pipe with threaded ends is formed by forming threaded portions at both ends of the fiber reinforced thermoplastic resin composite pipe in Example 1 by a thread cutting device that has been conventionally used for pipe construction. Got It should be noted that chips were generated during the formation of the threaded portion.

Comparative Example 2 The fiber reinforced thermoplastic resin composite pipe of Example 1 was not provided with a threaded portion because it was connected to the pipe joint with an adhesive. For the construction evaluation, 50 pipes (15) with screw at both ends of Example 1 were prepared, and female screw parts (16) were provided at both ends as shown in FIG.
A vinyl chloride resin pipe joint (17) having the above was wound with a sealing tape and screwed (referred to as A).

Further, 50 pipes with threaded ends were prepared in Example 2, and a polyethylene pipe joint having female threaded portions at both ends was wrapped with a seal tape and screwed and connected (referred to as B).

The same number of Comparative Example 1 as in Example 1 was connected to the pipe joint in the same manner (referred to as C).

Further, 50 threadless fiber-reinforced thermoplastic resin pipes of Comparative Example 2 were prepared, and the TS method (“Taper Sized Solvent
Abbreviation of "Welding Method", that is, a method of connecting pipes by inserting by utilizing the lubrication and elasticity of resin by an adhesive) and the pipe joint (referred to as D).
Warm water at 80 ° C is added to the above A to D at 3 kg / cm 2 1
After passing the water for an hour and inspecting for leaks, Table 1
It was as follows.

[0033]

[Table 1]

[0034]

According to the fiber reinforced thermoplastic resin composite pipe with a thread of the present invention, it is only necessary to screw the composite pipe into the female threaded pipe joint at the time of piping work, so that the composite pipe and the joint are connected. The work can be performed easily, and since the reinforcing fiber is not exposed on the screw surface, the reliability of the connection strength with respect to the joint is improved.

According to the manufacturing method of the fiber-reinforced thermoplastic resin composite pipe with a screw of the second aspect of the present invention, unlike the case where the thread is formed by cutting, no cutting chips are generated and the environment is not deteriorated. Since the screw portion is formed only by the outer layer of the thermoplastic resin, there is no risk of the fibers of the reinforcing layer being cut, and the fiber reinforcing effect of the reinforcing layer is not reduced.

[Brief description of drawings]

FIG. 1 is a partial perspective view showing an example of a fiber reinforced thermoplastic resin composite pipe used in the invention of claim 1, wherein an outer layer, a second reinforced layer and a first reinforced layer are partially cut out in order.

FIG. 2 is a vertical sectional view showing an example of a thread forming device used in the invention of claim 2;

FIG. 3 is a partial vertical cross-sectional view showing an example of the fiber-reinforced thermoplastic resin composite pipe according to the invention of claim 1.

FIG. 4 is a partially cutaway front view showing a state of connection with a joint when piping the fiber-reinforced thermoplastic resin composite pipe according to the invention of claim 1.

[Explanation of symbols]

 (1): Fiber reinforced thermoplastic resin composite pipe (5): Thermoplastic resin outer layer (10): Split mold (14): Threaded portion (15): Threaded fiber reinforced thermoplastic resin composite pipe

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Claims (2)

[Claims] 1. A thermoplastic resin outer layer is provided on at least an outer surface side of an outer surface and an inner surface of a fiber-reinforced thermoplastic resin composite pipe, and a screw portion is provided on an outer layer of at least one end of both ends of the composite pipe. A fiber reinforced thermoplastic resin composite pipe with a thread characterized by the following. 2. A thermoplastic resin outer layer is provided on at least the outer surface side of the outer surface and the inner surface of the fiber-reinforced thermoplastic resin composite pipe,
After heating the outer layer of at least one end of both ends of the composite pipe to soften the thermoplastic resin, press the end of the outer layer with a split mold for screw molding to form a screw part at the same end. A method for producing a fiber-reinforced thermoplastic resin composite pipe with a thread, which is characterized.