JP2000343578A - Production of polyolefinic liner pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To certainly and closely bond the outer surface of a liner pipe to the inner surface of a worn-out pipe to enhance the strength of the pipe. SOLUTION: A round pipe 12a having an outer diameter of a first size is extruded to be pulled downwardly to set the outer diameter of the pipe 12a to a second size almost same to the inner diameter of a worn-out pipe and, thereafter, a part of the round pipe 12a is pushed inwardly in a diameter direction to contract the outer diameter of the pipe 12a as a whole to form a liner pipe 12. This liner pipe 12 is inserted in the worn-out pipe and, when steam pressure is applied to the interior of the liner pipe 12 to restore the pipe 12 under heating, the outer diameter of the liner pipe 12 exceeds the second size to be expanded and the outer surface of the liner pipe 12 is closely bonded to the inner surface of the worn-out pipe.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a polyolefin-based liner pipe, and more particularly to a method for manufacturing a polyolefin-based liner pipe used for repairing and renewing an existing deteriorated pipe from the inside.

[0002]

2. Description of the Related Art Japanese Patent Application Laid-Open No. 64-56531 discloses an example of a method for manufacturing this type of liner pipe. This conventional technique extrudes a circular pipe from a mold,
By pressing a roller against the outer surface of the circular pipe, the wall of the pipe is deformed into a substantially U-shape.

[0003]

In the prior art, the outer diameter of a circular pipe extruded from a mold is set to be substantially the same as the inner diameter of an old pipe to be repaired or renewed. Therefore, even if the steam pressure is applied to the inside of the liner pipe to restore it to a circular shape, the outer surface of the liner pipe cannot be securely adhered to the inner surface of an old pipe, etc.
There was a problem that sufficient pipe strength could not be obtained.

[0004] Therefore, a main object of the present invention is to provide a method for producing a polyolefin-based liner pipe that can reliably adhere an outer surface to an inner surface of an aged pipe or the like.

[0005]

According to a first aspect of the present invention, a circular pipe having an outer diameter of a first size is extruded from a mold, and the outer diameter is reduced to a second size smaller than the first size by pulling down the circular pipe. This is a method for producing a polyolefin-based liner pipe, in which a part of a circular pipe is pushed radially inward.

A second invention has an outer diameter of a first size,
In addition, a circular pipe whose peripheral diameter is partially thickened is extruded from a mold, and the circular pipe is pulled down to have an outer diameter of a second size smaller than the first size. Is pressed radially inward to produce a polyolefin-based liner pipe.

[0007]

For example, a circular pipe having an outer diameter of a first size is extruded, and this circular pipe is pulled down, so that the outer diameter becomes a second size substantially equal to the inner diameter of an aging pipe or the like. Then, a part of the circular pipe is pushed inward in the radial direction to reduce the entire outer diameter. When repairing or updating an aging pipe or the like, a liner pipe is inserted into the aging pipe or the like, and steam pressure is applied to the inside of the liner pipe to restore it while heating. Then, due to the shape memory effect of the first size, the outer diameter of the liner pipe becomes the second diameter.
The diameter is expanded beyond the size, and the outer surface of the liner pipe is closely attached to the inner surface of an old pipe or the like.

[0008]

According to the present invention, the outer surface of the liner pipe can be securely brought into close contact with the inner surface of an aged pipe or the like. Therefore, the liner pipe and the aging pipe can be firmly integrated, and the pipe strength can be improved.

The above objects, other objects, features and advantages of the present invention will become more apparent from the following detailed description of embodiments with reference to the drawings.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for producing a polyolefin liner pipe according to one embodiment of the present invention is for producing a liner pipe 12 having a substantially heart-shaped cross section as shown in FIGS. This is performed using a manufacturing apparatus 10 as shown in FIG.

The manufacturing apparatus 10 includes an extruder 14, a first water tank 16, a second water tank 18, a take-off machine 20, and the like. The extruder 14 includes an extruder 24 for heating and melting and extruding a polyolefin-based resin (polyethylene, polybutene, polypropylene, or the like) supplied from a hopper 22, and a pipe molding die is provided at an outlet of the extruder 24. 26 is attached.

The mold 26 includes a substantially cylindrical die ring 28 and a solid mandrel 30 disposed inside the die ring 28, as shown in FIG. A cylindrical molten resin passage 32 is formed between the inner surface of the die ring 28 and the outer surface of the mandrel 30. The molten resin passage 32 has an outer diameter larger than the inner diameter of an old pipe to be repaired or renewed. The circular pipe 12a (FIG. 3) is extruded. As shown in FIG. 2 (B), the mandrel 30 is formed in a circular cross-section with a lower part missing in a crescent shape. Therefore, the cross section of the molten resin passage 32 becomes wider at the lower portion, and the thick portion 34 is formed at the lower portion of the circular pipe 12a as shown in FIG.

The first water tank 16 deforms the circular pipe 12a extruded from the extruder 14 into a substantially heart shape and cools the same. As shown in FIG. 4, the first water tank 16 extrudes the circular pipe 12a. A body 36 extends in the direction. A pipe inlet 38 and an outlet 40 are formed at one longitudinal end and the other end of the main body 36.
A plurality of openings 42 for maintenance / inspection and the like are formed on the upper surface, and a lid 44 is attached to each opening 42. The internal space of the main body 36 is divided into two by a partition wall 46, and the entrance 3
The base 50 is disposed in the first region 48 on the side of the outlet 8, and a vacuum pump 52 is connected to the first region 48 on the side of the outlet 40.
4 includes a diameter reducing jig 56 and a plurality (2 in this embodiment).
) Receiving rollers 58 are disposed. Also, the first area 4
8 and the entire length of the second region 54
2 (FIG. 7) are arranged.

The base 50 includes a cylindrical main body 64 having an inner diameter substantially the same as the inner diameter of an aged pipe or the like.
A flange 66 is formed on the outer periphery of one end of the flange 4, and the flange 66 is attached to the inlet 38.

The diameter reducing jig 56 is for deforming the circular pipe 12a into a substantially heart shape, and as shown in FIG. 5, the first portion 6 defining the upper outer surface of the circular pipe 12a.
8 and a second portion 70 for deforming the pipe wall of the circular pipe 12a into a substantially U-shape. The first portion 68 includes a substantially half-cylindrical cylindrical main body 72, and a flange-like mounting portion 74 is formed at one longitudinal end of the main body 72, and a flat support portion is formed at both circumferential ends of the main body 70. 76 is formed. A hole 80 for inserting a bolt 78 is formed in the support portion 76. The second portion 70 includes a bottom plate 82 that gradually increases in height in the extrusion direction of the circular pipe 12a and decreases in width. The second plate 70 rises from both ends in the width direction of the bottom plate 82 to form side plates 84. A total of four support portions 86 extend horizontally from the portion. Each support portion 86 is formed with a hole 88 through which a bolt 78 is inserted. In the center of the upper surface of the bottom plate 82, a circular pipe 12
Forming plate 90 gradually increasing in the extrusion direction of a
Is formed. Then, a bolt 78 is inserted from below into the holes 88 and 80 of the support portions 86 and 76, and a nut 92 is screwed into the bolt 78. Therefore, when the nut 92 is loosened, the second portion 70 is lowered, and when the nut 92 is tightened, the second portion 70 is raised.

The receiving roller 58 receives the liner pipe 12 deformed (diameter reduced) into a substantially heart shape by the diameter reducing jig 56, and further reduces the diameter thereof.
As shown in the figure, a pipe receiving portion 94a curved in a substantially U shape
And a body 94 having The main body 94 is connected to the rotating shaft 9.
4b rotatably supported.

The secondary water tank 18 is for further cooling the liner pipe 12 cooled by the primary water tank 16, and has a main body 96 substantially similar to the main body 36 of the primary water tank 16.
including. A watering pipe is disposed inside the main body 96, and cooling water is sprayed from the watering pipe toward the liner pipe 12.

The take-up machine 20 is for taking out the liner pipe 12 at a constant speed, and includes a take-up roller 98 pressed against the lower and upper parts of the liner pipe 12. A motor (not shown) is connected to at least one of the take-off rollers 98, and the take-up speed of the liner pipe 12 is adjusted by controlling the number of rotations of the motor.

When manufacturing the liner pipe 12 using the manufacturing apparatus 10 (FIG. 1), first, as shown in FIG. Lower 70. Also, 1
A negative pressure is applied to the first region 48 of the next water tank 16, and
Cooling water (about 10 to 20 ° C.) is supplied to each sprinkling pipe 62 of the secondary water tank 16 and the secondary water tank 18. Then, the extruder 14 is driven to start extruding the circular pipe 12a.

The circular pipe 12a extruded from the extruder 14 is provided to a base 50 of the primary water tank 16, and
The region 50 is pressed against the inner surface of the base 50 by the negative pressure applied. Therefore, the circular pipe 12a extruded from the mold 26 is pulled down in the process of reaching the base 50, and its diameter is reduced.

The circular pipe 12a that has passed through the base 50 is
While being cooled by the cooling water from the watering pipe 62,
It is provided to the second area 54. In the second region 54, the second portion 70 (formed plate 90) of the diameter reducing jig 56 is connected to the circular pipe 12.
Since the circular pipe 12a is lowered so as not to come into contact with the circular pipe 12a, the circular pipe 12a is cooled in a circular shape without being deformed.
When the circular pipe 12a is extruded for a predetermined length, the dimensions of the circular pipe 12a are measured, and the manufacturing conditions (such as the melting temperature of the resin) are adjusted so that the dimensions fall within an allowable range.

When the size of the circular pipe 12a is within the allowable range, the second portion 70 is pulled up and the forming plate 90 is pressed against the lower part of the circular pipe 12a while the extrusion of the circular pipe 12a by the extruder 14 is continued. . Then, the lower tube wall of the circular pipe 12a, that is, the thick portion 34
(FIG. 3) is pressed inward in the radial direction by the forming plate 90, and the thick portion 34 is deformed into a substantially U-shape to obtain the substantially heart-shaped liner pipe 12. When the molded plate 90 is pressed against the thick part 34, the thick part 34 is stretched and its thickness becomes thinner. However, since the thick part 34 is thicker than the other parts in advance, the liner The thickness is made uniform over the entire circumference of the pipe 12.

The liner pipe 12 obtained by the diameter reducing jig 56 is given to the receiving roller 58 while being cooled by cooling water. In the receiving roller 58, since the heat shrinkage of the liner pipe 12 proceeds along the inner surface of the receiving portion 94a, the diameter of the liner pipe 12 can be reduced efficiently without using any special means.

The liner pipe 12 passing through the primary water tank 16
Is further cooled by the secondary water tank 18 and then supplied to the take-off machine 20. When the liner pipe 12 having a predetermined length is taken by the take-up machine 20, a cutting device (not shown) is driven to cut the liner pipe 12.

According to this embodiment, the outer diameter of the circular pipe 12a extruded from the mold 26 is reduced to almost the same size as the inner diameter of an old pipe by pulling down the circular pipe 12a. When a steam pressure is applied to the inside of the pipe 12 to heat it, the liner pipe 12
However, the shape memory effect tends to return to the shape when extruded from the mold 26. That is, the liner pipe 12
Is expanded beyond the inner diameter of an aged pipe or the like. Therefore, when repairing or renewing an aging pipe or the like, the outer surface of the liner pipe 12 is closely attached to the inner surface of the aging pipe or the like, and the liner pipe 12 and the aging pipe or the like are firmly integrated.

The circular pipe 12 having the thick portion 34
a (FIG. 3), and the pipe wall is substantially U-shaped at the thick portion 34.
The liner pipe 1
2 can be made uniform over the entire circumference. Therefore, partial strength shortage can be resolved, and stable quality can be obtained.

In order to accurately deform the circular pipe 12a into a predetermined shape, it is necessary to appropriately set the temperature of the circular pipe 12a passing through the diameter reducing jig 56. For example, a spacer 100 as shown in FIG. 9 may be used. The spacer 100 includes a mounting plate 102 on which the diameter reducing jig 56 is mounted, and a mounting plate 1.
02 and a plurality of connecting rods 104 connecting the partition 46 to each other.
Is adjusted. In the primary water tank 16, since the temperature of the circular pipe 12a decreases as it moves toward the front in the extrusion direction, the circular pipe 12a can be deformed at the highest temperature when the spacer 100 is not used, and the spacer 100 is lengthened. The lower the temperature, the lower the temperature.

Even when the spacer 100 is not used, the jig 56 can be attached after the outlet 40 of the primary water tank 16, before the entrance of the secondary water tank 18, or inside the secondary water tank 18. Alternatively, the molding temperature of the circular pipe 12a may be adjusted. In these cases, it is desirable to keep the whole under negative pressure without bisecting the primary water tank 16.

Also, in the above-described embodiment, one formed plate 9
0, the circular pipe 12a is deformed. For example, as shown in FIG. 10, a plurality of molded plates 106 having different heights are formed on the upper surface of the bottom plate 82, and the circular pipe 12a is formed by these molded plates 106. You may make it deform | transform in steps.

Further, instead of the diameter reducing jig 56 (FIG. 5),
For example, a diameter reducing jig 108 as shown in FIG.
May be used. The diameter reducing jig 108 (FIG. 11) is a cylindrical first portion 1.
A second portion 118 having a peak portion 116 is disposed below a half-cylindrical portion 114 that constitutes a part of the second portion 12, while a diameter reducing jig 110 (FIG. 12) is a cylindrical first portion.
A second portion 122 having a roller 120 is disposed below a half-cylindrical portion 114 constituting a part of the portion 112. Also in these, the pipe wall (thick part 34) of the circular pipe 12a is formed by the peak part 116 or the roller 120.
Can be deformed into a substantially U-shape.

[Brief description of the drawings]

FIG. 1 is an illustrative view showing a liner pipe manufacturing apparatus;

FIG. 2 is an illustrative view showing a mold;

FIG. 3 is an illustrative view showing a circular pipe extruded from a mold;

FIG. 4 is an illustrative view showing a primary water tank;

FIG. 5 is an illustrative view showing a diameter reducing jig;

FIG. 6 is an illustrative view showing a second portion of the diameter reducing jig;

FIG. 7 is an illustrative view showing a roller and a liner pipe;

FIG. 8 is an illustrative view showing a state where a second portion of the diameter reducing jig is lowered.

FIG. 9 is an illustrative view showing a state where the position of the diameter reducing jig is changed;

FIG. 10 is an illustrative view showing a modified example of the second portion of the diameter reducing jig;

FIG. 11 is an illustrative view showing a modified example of the diameter reducing jig;

FIG. 12 is an illustrative view showing a modified example of the diameter reducing jig;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Manufacturing apparatus 12 ... Liner pipe 12a ... Circular pipe 14 ... Extruder 16 ... Primary water tank 18 ... Secondary water tank 20 ... Take-off machine 26 ... Die 34 ... Thick part 56 ... Diameter jig 90 ... Molding plate

────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] February 4, 2000 (200.2.4)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0005

[Correction method] Change

[Correction contents]

[0005]

According to the present invention, (a) a circular pipe having an outer diameter of a first size is extruded from a mold;
the outer diameter to the second size smaller than the first size by debiting the (b) a circular pipe, a (c) pushes a portion of the circular pipe radially inward, producing a polyolefin liner pipe.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0006

[Correction method] Deleted

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction contents]

The receiving roller 58 receives the liner pipe 12 deformed (diameter reduced) into a substantially heart shape by the diameter reducing jig 56, and further reduces the diameter thereof.
As shown in FIG. 5, the main body 94 has a concave portion curved in a substantially U-shape, that is, a pipe receiving portion 94a. And the body 9
4 is rotatably supported by the rotating shaft 94b.

Continued on the front page (72) Inventor Takachi Harada 64 Ishizukita-cho, Sakai-shi, Osaka F-term in Kubota Vinyl Pipe Factory (reference) 3H025 AA05 AB01 4F207 AA03 AG08 AG21 KA01 KA17 KA20 KL63 KL76 KL88 KW26 4F211 AA03 AG08 AG21 SA10 SC03 SD04 SG01

Claims (2)

[Claims] 1. A circular pipe having an outer diameter of a first size is extruded from a mold, and the outer diameter is reduced to a second size smaller than the first size by pulling down the circular pipe. A polyolefin-based liner pipe by pushing the rubber inward in the radial direction. 2. A circular pipe having an outer diameter of a first size and a part of which is made thicker in a circumferential direction is extruded from a mold, and the outer diameter is reduced to the first diameter by pulling down the circular pipe. A method for manufacturing a polyolefin-based liner pipe, wherein the second pipe has a second size smaller than the size, and the thickened portion of the circular pipe is pressed inward in the radial direction.