JPH08103968A - Plastic spiral winding double tube for propulsion method and manufacture thereof - Google Patents

Abstract

PURPOSE: To obtain a plastic spiral winding double tube which can be applied to a sewage pipe, etc., laid by a propulsion method and has a light weight, excellent strength and watertightness by arranging a spirally wound inner tube, a smooth outer tube and spiral protrusions for connecting both the tubes at the intermediate between the inner tube and the outer tube. CONSTITUTION: A plastic spiral winding double tube comprises an inner wall (inner tube) 1 formed of a spiral winding, a substantially smooth outer wall (outer tube) 2, and a spiral bandlike wall (spiral protrusions to the inner tube) 3 for connecting both the tubes 1, 2 at the intermediate between the tubes 1 and 2. The concrete structure example of the detail can employ, as shown in an enlarged sectional view of the wall, several molds according to manufacturing means. For example, in a corrugated tube having a bandlike material 4 which has, for example a finned U-shaped section and is spirally lap wound with a hollow part 5, a film 7 is spirally lap wound on an assumed cylindrical surface formed by connecting the outer surface 6 of the part 5 to form a double tube having substantially smooth surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention can be used in a propulsion method, and is a plastic helically wound double pipe for a propulsion method which is resistant to strong internal and external pressures and has watertightness as an underground drainage pipe. Related to the manufacturing method.

[0002]

Conventionally, an excavation method (or an excavation method) has been generally used for laying sewer pipes, laying water pipes, etc., but digging a trench by excavating from the ground surface. Therefore, it is necessary to close the road during the construction, and recently, unlike the excavation method, a vertical hole is dug in one place, and then a horizontal hole is excavated with a rotary cutter type mechanical excavator from there. The propulsion method of pushing in steel pipes and fume pipes has become popular.

However, steel pipes and fume pipes are heavy in weight and poor in flexibility, so that hard plastic pipes have been used instead. Hard plastic pipes conventionally used for this purpose are solid plastic pipes and corrugated pipes, but solid plastic pipes have low pressure resistance for their weight, and corrugated pipes have irregularities on the outer surface For this reason, the resistance when pushing into the lateral hole is large, and there is a concern that the outer surface is easily damaged and water leaks. Therefore, it is considered preferable to make the outer surface smooth. Such a thing is, for example, a substantially square shape,
A tubular body having symmetrically provided concave steps on the upper and lower wall surfaces, and fins provided at upper and lower diagonal positions, respectively, is spirally wound and fused, and at this time, the concave steps and fins are made to correspond to each other. Synthetic resin pipes with a smooth surface (No. 48-25214) are known, and as a smooth outer surface pipe for a different purpose, it is known as 55-4
No. 3704 is known.

However, from the viewpoint of plastics molding technology, in Japanese Utility Model Publication No. Sho 48-25214, it is difficult to fuse the side wall surfaces of the tubular bodies which are in contact with each other, and it is considerable to ensure that the strength and watertightness of the tubular body are maintained. Ingenuity is necessary, while Jitsuko Sho 55-437
A double pipe that fits the outer pipe to fill the irregularities on the outer surface of the corrugated pipe and smooth the outer surface as in No. 04 is considered unsuitable for mass production even if it is possible by hand. .

[0005] On the other hand, a method of making a plastics pipe by a spiral winding method is known. For example, Japanese Patent Publication 60-4772
And JP-A-60-18333. These are extruded from the extruder to extrude a molten plastic strip and supplied to the core metal.Then, the ends are overlapped and wound together so that their ends overlap each other, and they are sequentially moved in the axial direction of the core metal. The plastics spiral wound tube is formed by letting it go. The strip-shaped member is formed into a shape having a bulging portion continuous in the extrusion direction, that is, a U-shape with fins or a square-shape with fins, and these are overlapped with each other. It is possible to form a spirally wound tube in which a hollow strip is spirally wound. Such a spirally wound tube has a high pressure resistance due to the reinforcing strip, and is light in weight because the reinforcing strip is hollow. However, the pipe obtained by such a method has a smooth inner surface, but the outer surface has irregularities due to a bulging portion, and when used for the propulsion method as it is, friction with the soil is large and a large amount of energy is required for propulsion, There is a disadvantage that the bulging portion is easily damaged.

The present invention has developed a double pipe suitable for propulsion and a technique for manufacturing the same using such a plastic spiral wound pipe and a technique for manufacturing the same.

[0007]

SUMMARY OF THE INVENTION According to the present invention, while a plastics strip is spirally wound, a flexible reinforcing material is inserted inside the strip along the longitudinal direction of the strip to be integrated. On the assumed cylindrical surface formed by connecting the inner tube portion formed on the, the spiral convex portion of the trapezoidal cross section integrally formed on the surface of the inner tubular portion, and the outermost peripheral surface of the spiral convex portion. In addition, while spirally winding a plastics film or sheet having a width that spans two or more of the spiral convex portions separately from the inner tube portion, a plurality of layers are stacked and wound around the spiral convex portions. A plastic spiral-wound double tube for a propulsion method, which is composed of an integrally formed substantially smooth outer tube portion.

The present invention is also directed to a trapezoidal shape formed by spirally winding a plastic strip and partitioning a reinforcing hollow portion on the surface of the strip along the longitudinal direction of the strip. An inner tube portion having a helical convex portion having a cross section, and the helical convex portion formed separately from the inner tube portion on an assumed cylindrical surface formed by connecting the outermost peripheral surface of the helical convex portion. A plastics spiral for a propulsion method comprising a substantially smooth outer tube portion formed by laminating and winding a plurality of layers on the spiral convex portion while spirally winding a plastics film or sheet having a width extending over the above. It is a wound double tube.

That is, the present invention facilitates press-fitting into soil by forming a specific double pipe by spirally lap-joining to form a specific double pipe, and by making the outer pipe portion substantially smooth. It is to be able to withstand large pressure applied to the soil. According to another aspect of the present invention, a plastics strip in a molten state is supplied from an extruder around a cylindrical mandrel so that its cross section is bent or hollow, and a part of the strips is overlapped. Spirally wound,
Thereby, the inner tube portion and the helical convex portion outside the inner tube portion are integrally formed, and then plastic molded in advance on an assumed cylindrical surface formed by connecting the outermost peripheral surface of the helical convex portion. Or a plastic film or sheet in a molten state is supplied from an extruder, spirally wound and welded to form a substantially smooth outer tube integrally. It is possible to provide a method for manufacturing a spirally wound plastic double tube for a propulsion method. That is, first, the circular tube portion and the spiral ridge portion are formed by spirally overlapping and joined, and then the plastic sheet or film is spirally overlapped and formed on the outer peripheral surface of the spiral convex portion.

Here, the inner tube portion and the spiral ridge portion can be easily formed by forming the cross section of the plastic strip into a U-shaped portion and a fin portion integrally extending from its free end. . On the other hand, a substantially smooth outer tube portion can be formed by spirally winding and welding a plastic film or sheet. Even if the film or sheet is preformed,
It may be supplied in a molten state from an extruder.
It is set to 0.5 to 30 mm, preferably 1.0 to 10 mm. The outer diameter of the double pipe is 50 to 3000 mm. As described above, when the continuous core material is inserted into the hollow portion formed of the synthetic resin strip in the molten state to maintain the shape of the spiral convex portion, the continuous core material is formed of the spiral convex portion. It functions as a cap for closing the cut portion when the outermost peripheral portion is cut and taken out.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, a schematic (membrane type) structure of a plastics spirally wound double tube of the present invention is shown in a cross section parallel to its axis as shown in FIG. 1 and formed by spiral winding. By the inner wall 1 (inner pipe part), the substantially smooth outer wall 2 (outer pipe part), and the spiral band wall 3 (helical convex part for the inner pipe part) which is an intermediate part and connects both pipes. It is configured. The detailed structural example of the details is an enlarged schematic cross-sectional view
As shown in FIG. 8, several forms can be taken depending on the manufacturing means.

In FIG. 2, a corrugated tube having a hollow portion 5 is formed by spirally winding a belt-shaped member 4 having a U-shaped cross section in a helical shape (a spiral tube integrally formed on the inner tube portion and the surface thereof). A spiral concave portion is formed along the spiral convex portion.) The film 7 is spirally formed on an assumed cylindrical surface formed by connecting the outer surface 6 of the hollow body. A double tube having a substantially smooth surface is formed by lap winding.

In FIG. 3, when a hollow section 5 is formed by spirally winding a U-shaped strip 4 having a fin-shaped cross section in the same manner as in FIG. Flexible continuous core material
(Hereinafter, abbreviated as "shape retention belt") is inserted and fitted, and after cooling, the outer center portion of the hollow portion 5 is torn to take out the shape retention belt, and the film 7 is spirally formed as in FIG. A double tube having a substantially smooth surface is formed by overlapping and winding. This drawing shows a case where the band-shaped body 4 is a U-shaped part with a rib 8 provided in advance and is cut at the center of the rib 8.

In the double tube of FIG. 4, after the cap band 9 is put on the cut portion in FIG.
Is spirally wound around. The double tube in FIG.
A corrugated tube having a hollow portion 5 is formed by spirally winding one fin-shaped U-shaped band 4 having a cross section, which is a variation of the fin-shaped U-shaped band. Hollow part 5
The film 7 is spirally wound around a cylindrical surface formed by connecting the outer side surfaces 6 of the film to form a substantially smooth surface.
In FIG. 6, the cross-section is a U-shaped band with a fin, and the univariate band 4 whose U-shaped direction is reversed is helically wrapped and wound to form a double tube. The film 7 is spirally wound around a cylindrical surface formed by connecting the side surfaces, and the surface is formed substantially smooth.

In the double pipe shown in FIG. 7, a reinforcing pipe 4a as a flexible reinforcing material formed in advance is supplied into the inside of the strip 4 to form a spiral convex portion having a trapezoidal cross section, and the spiral is formed. A plastic sheet is wrapped around at least two or more adjacent outer peripheral surfaces of the convex portion, and the surface is finished almost smoothly. The cross-sectional shape of the spiral convex portion of the belt-like body may be a quadrangle, a mountain, or the like, in addition to the trapezoid in this example.

In the double pipe of FIG. 8, in addition to that of FIG. 7, a U-shaped cross section (can take various cross sections such as a circle and a square) along the joint of the adjacent strips 4 is provided. Of the stainless steel member 4b is continuously supplied. This metal member 4b can be used not only for reinforcement but also for detecting a joint failure at the joint portion as follows. That is, while the corrugated pipe is held on the mandrel (before winding the plastic sheet), the dielectric terminal of the high-voltage, high-frequency generator is brought close to the outer peripheral end of the joint of the corrugated pipe from the outside, and By monitoring the occurrence of a stable spark between the dielectric terminal and the metal member, it is possible to confirm the adhesion or bonding of the bonding portion. An elongated metal member, for example, a piano wire having a circular cross section can also be inserted into the joint portion of the double-tube plastic sheet shown in FIG.

Various devices can be used as a device for manufacturing the spirally wound double tube of the present invention. FIG. 9 shows an example of the device shown in FIG. Was.
Next, this device and its operation will be described with reference to FIGS. 9 to 11. FIG. 9 is a schematic top view of the entire device, FIG. 10 is a schematic cross-sectional view of a band, and FIG. 11 is formed. 3 is a schematic cross-sectional view of the wall of an emerging tube. A belt-shaped body 4 of plastics (hard polyethylene resin) having a U-shaped fin with a cross section extruded in a molten state from the main extruder 10 as shown in FIG. 10 is wrapped around a mandrel. However, the strip 4 may be extruded in a flat plate shape and applied to a forming guide to form a U-shaped bulging portion 11. The shape may correspond to the cross-sectional shape (shape as shown in FIG. 10) of the belt-shaped body 4 having the shape.

In principle, the apparatus comprises a plurality of rolls 1 arranged in a cylindrical shape at a position in contact with the inner surface of the tube to be formed.
2-1, 12-2, 12-3, 12-4,..., And the rolls are inclined at a fixed angle with respect to the axis 13 (also the axis of the pipe to be formed) in substantially the same cylindrical plane. This group of rolls is simultaneously driven by the driving device 14, and the belt is slightly pulled in the direction in which the extruded belt 4 is wound up, and all the rolls are rotated at the same speed, Since the rolled-up band 4 is moved in the axial direction by the inclination of the roll group 12, if the degree of the inclination is adjusted, the band 4 after one turn will be wound up with a constant overlap. A shape-retaining belt 15 is inserted or fitted in the U-shaped bulging portion 11 while being rolled up. The shape retaining belt 15 is, for example, a rubber V-belt, a spring wire, or the like.

In order to explain the operation of the band 4 and the shape retaining belt 15, a cross section of the wall of the tube being formed in FIG. 9 is shown in FIG. At the initial stage of winding the belt-shaped body 4 around the core bar, the flat part 1 of the band-shaped body 4 is fitted around the bulged part 11 and wound around the bulged part 11 by being wound together.
6, the shape-retaining belt 15 is confined in the hollow portion formed. After leaving the sealing for a few rotations, the center of the tip of the bulging portion is cut open by the cutter 17, and the shape-retention belt 15 is rotated several times. After being rolled up, it is taken out.
It is preferable that the removed shape retaining belt 15 is taken up by the cooling guide roller 18, and is sequentially moved to a position where it is first wound together with the belt-shaped body 4, so as to be an endless continuous core material.

The outer surface of the bulging portion 11, that is, the valley portion between the ridges formed by the bulging portion 11, that is, the strip 4 which is one round front in 19 of FIG. In order to strengthen the joint, the pressing belt 20 may be wound around the tube being formed by a mechanism similar to that of the shape-retaining belt 15 and continuously pressed. In the figure, the pressing belt 20 is taken out before taking out the shape retaining belt 15. Shape keeping belt 1
Since the torn portion 21 from which 5 has been taken out naturally returns substantially to the original shape, the cap band 9 extruded from another cap band extruder 22 is extruded and coated thereon. The cap band 9 causes the flow of the extruded resin to flow over the tearing portion 21, but the bulging portion 1 immediately before the cap band 9 is covered to strengthen the bond.
1 may be heated by a heater 24 or after being covered with the cap band 9, it may be pressed down by a pressing roll 23.

As a heating method in the heater 24, various local heating methods such as blowing of hot air and a far-infrared heater can be used. Then, while extruding the flat band-shaped film 7 from another film extruder 25, the film is spirally wrapped around an assumed cylindrical surface formed by connecting the outer surfaces of the cap band 9 to form an outer tube. The film 7 is wrapped in multiple layers so that the width of the film 7 extends over two or more of the bulging portions 11 of the pipe to be covered. Further, the outer tube may be formed by increasing the width of the film and, for example, winding the film several times over three to four bulging portions.

The core metal shown in the apparatus of FIG. 9 is an apparatus for easily producing a pipe having a fixed pipe diameter and a constant helical pitch. This apparatus is capable of forming a spirally wound pipe having an arbitrary pipe diameter and a helical pitch. In order to change the pitch of the spirally wound tube, the angle formed by the rolls with respect to the axis of the spirally wound tube may be adjusted in order to change the pitch of the spirally wound tube. Since a person skilled in the art can easily combine various mechanisms, a description thereof will be omitted.

In the case of FIG. 2, in the apparatus of FIG. 9, the shape-retaining belt 15, the cap belt extrusion molding machine 22, and the cutter 17 are used.
The use of the cap strip extruder 22 in the apparatus shown in FIG. 9 may be stopped in the case of FIG. In the case of FIG. 5, in the apparatus of FIG. 9, the base of the main extrusion molding machine 10 is formed into a fin-shape corresponding to FIG. 22, use of the cutter 17 may be stopped.

In the case of FIG. 6, the cap of the main extruder 10 in the apparatus of FIG. 9 is formed into a modified U-shape corresponding to FIG. The use of 17 should be stopped. When the plastics spiral wound double pipe of the present invention is joined, for example, an extrapolation type packing 26 can be used as shown in FIG.
As shown in the figure, the protrusion of the packing into the pipe is small and the flow in the pipe is not hindered as compared with the conventional plastics spiral wound pipe which cannot be used unless the internal packing 27 is used. The plastics spiral wound double pipe of the present invention can be manufactured without substantially changing the conventional plastics spiral wound pipe manufacturing method, so that productivity is good.

Here, the excellent pressure resistance of the pipe of the present invention will be described by way of examples. Experimental Example FIG. 14 was molded as an example of the product of the present invention using the production apparatus shown in FIG.
Not used). On the other hand, as a comparative example, the one shown in FIG.
7. The film extrusion molding machine 25 is not used.

I) Manufacturing conditions a. Main extruder Cylinder temperature 170-190 ℃ Cap temperature 180 ℃ b. Film extrusion molding machine Cylinder temperature 180 ~ 200 ℃ Cap temperature 220 ℃

II) Resin used High density polyethylene (specific gravity 0.95) (band and sheet) III) Sample A tube having an inner diameter of 450 m / mφ was obtained under the above conditions. However, the thickness of the strip is 1.2 m / m, the outer width of the spiral ridge is about 31 m / m, the height is about 30 m / m, and the thickness of the sheet is 0.6 m / m. IV) Withstand voltage test conditions a. Testing machine Compression tester manufactured by Toyo Seiki Seisaku-sho, Ltd. Model T5-S Measurement temperature 23 ± 1 ℃ c. Compression speed 10mm / min d. Sample length 500m e. Number of samples 5 V each) Results of pressure test

[0028]

[Table 1] VI) As described above, the results of the pressure test show that the pipe of the present invention (FIG. 14) is about 30% more reinforced than the comparative pipe (FIG. 15).

[0029]

Since the outer surface of the plastic spiral wound double pipe for the propulsion method according to the present invention is smooth, when used for sewer pipes, water pipes, etc. laid by the propulsion method, the weight is low. In addition, it is easy to lay, there is little damage when laying the pipe itself, and after laying, it has the strength to withstand strong pressure from inside and outside, and has good watertightness. According to the method of manufacturing a plastic spirally wound double pipe for a propulsion method according to the present invention, productivity can be improved because it can be manufactured without essentially changing the conventional method of manufacturing a plastic spirally wound pipe.

[Brief description of drawings]

FIG. 1 is a schematic view of a partially cut side structure of an example of a plastics spirally wound double tube for a propulsion method according to the present invention.

FIG. 2 is a schematic cross-sectional view of a tube wall showing another embodiment of the tube of the present invention.

FIG. 3 is a schematic sectional view of a wall portion of a tube showing another embodiment of the tube of the present invention.

FIG. 4 is a schematic cross-sectional view of a tube wall showing another embodiment of the tube of the present invention.

FIG. 5 is a schematic cross-sectional view of a tube wall showing another embodiment of the tube of the present invention.

FIG. 6 is a schematic sectional view of a wall portion of a pipe showing another embodiment of the pipe of the present invention.

FIG. 7 is a schematic cross-sectional view of a tube wall showing another embodiment of the tube of the present invention.

FIG. 8 is a schematic cross-sectional view of a tube wall showing another embodiment of the tube of the present invention.

9 is a schematic top view showing an example of a tube manufacturing apparatus according to the embodiment shown in FIGS. 1 to 8. FIG.

FIG. 10 is a schematic sectional view of an example of a band-shaped body.

FIG. 11 is a schematic cross-sectional view of a tube being formed by the manufacturing apparatus of FIG. 9, which is parallel to the plane of the paper.

FIG. 12 is a schematic sectional view showing an example of a connecting portion of the pipe of the present invention.

FIG. 13 is a schematic sectional view showing a connecting portion of a conventional spirally wound tube.

FIG. 14 is a diagram corresponding to FIG. 2 of an example of a plastic spirally wound double tube of the present invention used in an embodiment.

FIG. 15 is a diagram corresponding to FIG. 2 of a conventional one used as a comparative example of FIG. 14;

[Description of sign]

 DESCRIPTION OF SYMBOLS 1 Inner wall (inner pipe part) 2 Outer wall (outer pipe part) 3 Strip-shaped wall (spiral convex part) 4a Reinforcement pipe (flexible reinforcing material) 5 Hollow part 7 Film

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Claims (5)

[Claims] 1. An inner tube portion formed integrally by inserting a flexible reinforcing material into the inside of the plastic strip along the longitudinal direction of the plastic strip while spirally winding the plastic strip. ,
A spiral convex portion having a trapezoidal cross-section integrally formed on the surface of the inner pipe portion, and an inner cylindrical portion formed on the assumed cylindrical surface formed by connecting the outermost peripheral surface of the spiral convex portion are different from the inner pipe portion. A substantially smooth outer tube formed by integrally winding and forming a plurality of layers on the spiral convex portion while spirally winding a plastics film or sheet having a width over two or more of the spiral convex portions in a body. Spiral spiral wound double pipe for propulsion method consisting of a part. 2. A spiral having a trapezoidal cross section integrally formed by spirally winding a plastic strip and partitioning a reinforcing hollow portion on the surface of the strip along the longitudinal direction of the strip. The inner tube portion having the convex portion and the inner tube portion are separately formed on the assumed cylindrical surface formed by connecting the outermost peripheral surface of the spiral convex portion and straddle two or more of the spiral convex portions. A plastics spiral wound double for propulsion method comprising a substantially smooth outer tube portion formed by laminating a plurality of layers on the spiral convex portion while integrally winding a plastics film or sheet having a width in a spiral shape. tube. 3. A molten plastic strip is supplied from an extruder around a cylindrical mandrel so that its cross section is bent or hollow, and is spirally formed so as to partially overlap each other. An assumed cylindrical surface formed by winding, thereby integrally forming an inner tube portion and a spiral convex portion having a trapezoidal cross section outside the inner tube portion, and then connecting the outermost peripheral surface of the spiral convex portion Supplying a preformed plastics film or sheet having a width over two or more of the spiral convex portions or supplying a molten plastic film or sheet from an extruder onto the spiral convex portion A spirally wound double pipe for a propulsion method, wherein a plurality of layers are spirally wound and welded together to form a substantially smooth outer pipe. 4. A cross section of a plastic strip supplied in a molten state comprises a U-shaped portion and a fin portion integrally extending from at least one free end of the U-shaped portion. The manufacturing method according to claim 3, wherein the fin portion forms a spiral convex portion, and the fin portion forms an inner tube portion. 5. A plastics strip in a molten state is supplied from an extruder around a cylindrical mandrel and spirally wound so as to partially overlap each other. Is continuously and simultaneously supplied to the inside of the plastic strip to form a spiral convex portion having a trapezoidal cross section on the surface, and then an assumed cylindrical surface formed by connecting the outermost peripheral surface of the spiral convex portion. On the top, a preformed plastics film or sheet having a width extending over two or more of the spiral convex portions is supplied, or a molten plastic film or sheet is supplied from an extruder to form the spiral convex portion. A method for manufacturing a plastics spiral wound double pipe for a propulsion method, wherein a plurality of layers are spirally overlapped and welded on a portion to form a substantially smooth outer pipe section.