JPH04163148A - Reinforced plastic composite pipe composed of a plurality of resin mortar layers and its manufacture - Google Patents

Abstract

PURPOSE:To prevent the strength per unit from being deteriorated even when the thickness of a pipe increases by a method wherein an internal layer and an external layer are formed with fiber reinforced plastic layers, and at least between two layers of resin mortar layer and between both layers, a fiber reinforced plastic layer is placed. CONSTITUTION:By spirally winding a plastic reinforced band shaped body 6A, for which a glass fiber is immersed in a heat curing type plastic liquid, on a core cylinder 4, an internal layer 7 is formed. A material for which the heat curing type plastic is blended and mixed with sand grain, etc., is formed into a band shaped body 9A from a press-out device 8A to form a first resin mortar layer 10A, and on the top of it, by winding a plastic reinforced band shaped body 6B spirally, a first intermediate reinforced layer 11 is formed. To a pipe shaped body which is withdrawn from a first curing oven 12A, a second band shaped body 9B is continuously wound on the surface spirally from a second press-out device 8B, to form a second resin mortar layer 10B. In addition, a third plastic reinforced band shaped body 6C is wound spirally, and the pipe shaped body is induced to a second curing oven 12B again.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a reinforced plastic composite pipe in which the inner and outer layers are formed of fiber-reinforced plastic layers, and the intermediate layer is formed of a resin mortar layer.

[Conventional technology] Focusing on the properties of fiber-reinforced plastics such as strength, corrosion resistance, and light weight, composite pipes in which a resin mortar layer is interposed as an intermediate layer to strengthen rigidity are widely used as underground sewer pipes. It is used.

By taking advantage of the characteristics of both materials, it can withstand corrosive conditions when buried underground, withstand external pressure due to the weight of earth and sand, and can withstand vibrations, shocks, and uneven pressure caused by earthquakes and the passage of heavy vehicles. It has a high resistance to strong external forces.

Such a composite pipe requires a structure in which the fiber-reinforced plastic layers that form the inner and outer layers and the resin mortar layer that is the intermediate layer overlap closely as one unit to resist the applied external pressure. , several proposals have been announced for this manufacturing method.

As an example, in Japanese Patent Publication No. 48-37139, Figures 4(a) and 4(b), a strip 3a of cardboard or the like is spirally wound around a mandrel 1a to form a core tube 4a.
A strip 6a of fiber (or woven fabric or non-woven fabric) impregnated with a thermosetting plastic liquid is wound thereon to form an inner layer 7a, and then the thermosetting plastic is kneaded into a base material such as sand. The resin mortar layer 1 is formed by squeezing out the material to a desired thickness T and spirally winding the strip 9a.
Form 0a. Various methods can be applied to form this band-like body, but in this reference, the above-mentioned mixed wire material is supplied from the upper part of one end of a cylinder 51 with a rotary screw 50 pivotally supported inside, and is forced by a screw toward the other end. A squeezer 8a is used to extrude the compression-molded strip from a rectangular opening at the other end while feeding the strip. This strip 9a is sent out as it is and tightly wound on top of the inner layer 7a, and then a fiber strip 6b impregnated with a thermosetting plastic liquid is wound again on top of this to form the outer layer 13a. Up to this point is the process of forming a composite tube, and the three-fold cumulative layer formed on the mandrel and its outer surface continues as it is and is evenly heated from the outer periphery in the curing oven 12a, forming an inner layer, an outer layer, and an intermediate layer between them. The blended thermosetting resin hardens to form a strong composite tube.

As mentioned above, a considerable number of proposals have been published in this technical field, and another example is the method of squeezing out a resin mortar layer as shown in Figures 5 (a) and (b) of Japanese Patent Publication No. 1177/1983. However, the cross-wire material that naturally falls from the feeder 53 is squeezed out into a band from a rectangular opening formed between the partition plates 54 and 54 on both sides and the rotating roller 55 by its own weight and the friction of the rotating rollers. There is also.

[Problem to be solved by the invention] Recently, the use of reinforced plastic pipes with a resin mortar layer has expanded, and the increasing demand for increasing the inner diameter of the pipes can be said to be a natural progression from the improvement of urban functions. .

Increasing the diameter of the pipe will naturally amplify the earth pressure and sudden vibrations that are applied to the pipe, so to withstand this it is necessary to increase the wall thickness of the pipe. In this case, for example, when the pipe thickness is 1211 mm, the structure of each layer is: inner layer (fiber reinforced plastic layer) 1.5 mm, middle layer (resin mortar layer) 9
If setting the outer layer (same as the inner layer) to 1.5 mm is the best combination of strength and rigidity, then the pipe thickness should be 3 mm.
Even when it is necessary to double the ratio, the above ratio can be used as is: inner layer: 4.5 mm, intermediate layer: 27 HL, outer layer: 4.5 mm.
mm, a total of 36 mm is considered to be the most balanced configuration.

However, it is known from experience that this calculation no longer holds true when the pipe thickness exceeds a certain upper limit. For example, it is recognized that when the thickness of the intermediate layer exceeds 251 mm, the strength and rigidity per unit area of the tube decrease significantly.

The main reason for this is thought to be the formation process of the resin mortar layer. In other words, as per the definition of mortar, resin mortar is made by mixing sand grains with liquid resin and kneading it, and although it depends on the amount of resin, it generally takes the form of a paste, and when squeezed out through a narrow opening, whether by extrusion or squeezing, it becomes a strip. Although it can be molded, it is difficult to maintain this shape by itself, and as shown in Figure 4 (
In (b), the strip 52 of nonwoven fabric or the like is attached to the bottom of the mortar layer to prevent it from deforming during movement. The same applies to the tape 56 in FIG.

With mortar of this nature, the thickness of the formed strip can be changed by changing the opening, but as long as the means of squeezing remains the same, as the formed object becomes thicker, the compacted coal will gradually become smaller. I don't get it.

Apart from the limit on the thickness of the resin mortar layer during the molding process, problems arise due to heat curing.

That is, as the layer thickness increases, it is a natural consequence that the time required for heating the entire surface from the outer periphery increases, and all steps in the continuous pipe manufacturing process lose their equilibrium here and suffer from abnormally low productivity.

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention aims to provide a thick-walled reinforced plastic composite pipe in which the strength per unit does not deteriorate even when the wall thickness of the pipe increases, and a method for manufacturing the same.

[Means for Solving the Problems] The reinforced plastic composite pipe according to the present invention has an inner layer and an outer layer formed of fiber-reinforced plastic layers, and has at least two resin mortar layers and a fiber-reinforced plastic layer interposed between the two layers. By doing this, the above problem was solved.

More specifically, it was also shown that an embodiment in which the thickness of the resin mortar layer does not exceed 25 mm is most desirable.

In addition, as a manufacturing method for such a reinforced plastic pipe consisting of a plurality of mortar layers, a core cylinder is formed by winding a strip in a spiral shape on a mandrel, and a thermosetting plastic liquid is impregnated onto the core cylinder. A plastic reinforced belt made of fibers is spirally wound to form an inner layer, and a material made by kneading thermosetting plastic with sand or the like is squeezed out to a predetermined thickness onto the inner layer, and the belt is spirally wound. The plastic reinforcing strip is wound spirally onto the first resin mortar layer to form an intermediate reinforcing layer, and the three layers of polymer are evenly distributed from the outer periphery. The second resin mortar layer is formed by heating and curing the intermediate reinforcing layer, and the second resin mortar layer is formed by spirally winding the band on the intermediate reinforcing layer in substantially the same manner as the first resin mortar layer. This problem is solved by the process of alternately winding the mortar layer in a spiral shape and repeating heating and hardening each time, and then spirally wrapping the plastic reinforced band around the outermost layer that has reached the desired pipe thickness to tightly cover the whole. solved.

Furthermore, the most desirable embodiment is that the thickness of the resin mortar strips to be squeezed out does not exceed 25 mm.

[Function/Example] FIG. 1 is a front view showing an example of the manufacturing method of the present invention.

One end of the mandrel 1 is supported horizontally by a support frame 2, and a strip 3 such as cardboard is wound diagonally around this as a core material to continuously form a core tube 4. In this figure, the endless belt 5t rotates and due to the friction between the belt 3 and the belt, the belt is spirally wound around the mandrel and moves to the right in the figure while sliding, continuously forming the core cylinder 4. A preferred embodiment is shown below.

An inner layer 7 is formed by winding a plastic reinforced band 6A made of glass fibers impregnated with a thermosetting plastic liquid in a spiral shape onto the core cylinder 4.

A material obtained by blending and kneading thermosetting plastic with sand grains or the like is molded into a strip 9A from a squeezer 8A to form a first resin mortar layer 10A, and then a plastic reinforced strip 6B is further spirally formed on top of the first resin mortar layer 10A. to form the first intermediate reinforcing layer 11.

Subsequently, this accumulated layer moves in one piece to the right and enters the interior of the first curing oven 12A. The curing oven is a tunnel furnace that heats the tubular material evenly from the entire circumference, for example, 130 degrees until it exits from the right end of the figure, all the way to the inner layer.
Heat to about C to harden. In this case, resin mortar layer 1
It is necessary to set the layer thickness of 0A below a limit value known empirically in advance, and it is most desirable to set the thickness to 25 mm for resin mortar layers of currently known reinforced plastic composite pipes.

Following the tubular body exiting the first curing oven 12A, a second belt-like body 9B is spirally wound around the surface from the second squeezer 8B to form a second resin mortar layer 10B. Furthermore, the third plastic reinforced strip 6C is wound spirally and guided into the second curing oven 12B again. At this stage, when the pipe thickness has reached the desired dimension, the surface layer formed by the third plastic reinforced strip 6C becomes the outer layer 13, and when the pipe thickness is insufficient, this surface layer becomes the outer layer 13. The same procedure will be repeated for the second intermediate layer.

The long tube molded and hardened in this manner is appropriately cut into a predetermined length to produce a finished product, or if necessary, after complete cooling, the innermost core cylinder 4 is pulled out to expose the inner layer 7 on the inner surface.

FIG. 2 is a partial cross-sectional view of the finished product, in which a plurality of relatively dense resin mortar layers are combined to exhibit an effect of maintaining strength against bending stress, which is approximately proportional to the wall thickness.

[Effects of the Invention] The present invention forms a plurality of resin mortar layers in the middle, each of which is individually limited to a layer thickness within the density limit, and is heated and hardened by being separately exposed to external heat for an appropriate period of time. By doing so, it is possible to obtain a strength approximately equal to the sum of the strengths of each individual resin mortar layer.

Since only the appropriate heating time based on the limited layer thickness can be applied from the outer periphery, multiple thermal curing processes can proceed simultaneously and separately in the assembly process. In the past, curing a thick resin mortar layer that exceeded the limit required long heating times, resulting in adverse effects such as temperature unevenness between the inner and outer layers and overheating deterioration in the vicinity of the outer layer. Improved work efficiency. At the same time, significant improvements in quality were also observed.

The effects of the present invention are illustrated in FIGS. 3(a) and 3(b) in comparison with the prior art.

FIG. 3(A) shows the relationship between load and deflection when a line load P is applied to a tube sandwiched between upper and lower sides by rubber plates G as shown in FIG. 3(B) as a result of an external pressure test.

The two curves both have an inner diameter of 2000+ nm and a tube thickness of 40 μl.
The test results for the reinforced plastic composite tube shown in Figure 2 show that the tube manufactured according to the present invention, indicated by the chain line, has significantly higher strength and rigidity than the tube manufactured according to the conventional technique, indicated by the solid line.

The tube made in accordance with the present invention is made of two layers of resin mortar with a layer of fiber-reinforced plastic interposed between the two layers, but is otherwise made under the same conditions as the prior art tube.

[Brief explanation of drawings]

FIG. 1 is a front view showing an embodiment of the method according to the present invention, and FIG.
The figure also shows a part of a vertical sectional view showing an example of the product.
Figure (a) (opening) is a diagram showing the external pressure test results of the example and its test method, Figure 4 (a) (opening) is a front view and side view showing the conventional technology, and Figure 5 (a) ( Figure 3) is a front view and side view showing another conventional example. 1... Mandrel 3... Band-shaped body (core material) 4... Core cylinder [iA, 6B... Plastic reinforced band-shaped body 7
...Inner layer 8A, 8B...Expressor 9A, 9B...Strip body (resin mortar) 10A,
IOB...Resin mortar layer 11...
Intermediate reinforcing layer J2A, 12B...Curing oven 13...
・Outer layer

Claims (4)

[Claims] (1) A reinforced plastic composite consisting of a plurality of resin mortar layers, characterized in that the inner layer and the outer layer are formed of fiber-reinforced plastic layers, and at least two resin mortar layers and a fiber-reinforced plastic layer are sandwiched between both layers. tube. (2) A reinforced plastic composite pipe comprising a plurality of resin mortar layers according to claim 1, wherein the thickness of each resin mortar layer does not exceed 25 mm. (3) A core tube is formed by winding a strip around a mandrel in a spiral manner, and a plastic reinforced strip made of fibers impregnated with a thermosetting plastic liquid is wound around the core tube in a spiral manner to form an inner layer. A first resin mortar layer is formed by squeezing out a material obtained by kneading sand or the like and thermosetting plastic onto the inner layer to a predetermined thickness and spirally winding the band-shaped body.
The plastic reinforcing strip is spirally wound again onto the first resin mortar layer to form an intermediate reinforcing layer, and the three layers of polymer are uniformly heated and hardened from the outer periphery, and a second reinforcing layer is formed on the intermediate reinforcing layer. A second resin mortar layer is formed by spirally winding the strip in almost the same manner as the first resin mortar layer, and then, if necessary, the intermediate reinforcing layer and the resin mortar layer are alternately wound spirally. is a reinforced plastic composite consisting of multiple resin mortar layers, which is characterized by repeating heating and curing each time, and then spirally wrapping the plastic reinforced band around the outermost layer that has reached the desired pipe thickness to tightly cover the whole. Method of manufacturing tubes. (4) A method for manufacturing a reinforced plastic composite pipe comprising a plurality of resin mortar layers according to claim 3, characterized in that the thickness of each resin mortar strip to be squeezed out does not exceed 25 mm.