JP2002248674A - Liner tube and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a saddle branching joint or the like to be surely connected to a liner tube by forming the liner tube in a substantially true circle when the tube is restored in an existing tube. SOLUTION: A press-in part 18 provided at the liner tube 10 is pressed in and deformed, and when the deformed tube 10 is heated and pressurized, the tube 10 having a predetermined radius R2 of curvature is restored. In this case, the part 18 does not completely restore its original shape, but since a radius R1 of curvature of the part 18 is reduced as compared with the predetermined radius R2 of the curvature, the tube 10 after the restoring is of a true circle of the predetermined radius R2 of the curvature.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art FIG. 1 used for the construction of a bent portion of an existing pipe.
As shown in FIG. 14 (B), the liner tube 1 shown in FIG. 4 (A) is subjected to diameter reduction by pressing a pressed portion 1a formed in a part of the tube 1 in a circumferential direction with a pressing plate or the like. I have. The reason why the diameter reduction processing is performed in this way is to reduce the insertion resistance to the existing pipe. Then, in a state where the liner pipe 1 subjected to the diameter reduction processing is inserted into the existing pipe, heating steam of a predetermined pressure is supplied to the inside of the liner pipe 1 to restore the pipe to a pipe having a substantially circular cross section (FIG. 14 (C)). As a result, the existing pipe can be repaired and renewed by bringing the liner pipe 1 into close contact with the inner peripheral surface of the existing pipe.

However, as shown in FIG. 14 (C), the pushed-in portion 1a of the liner tube 1 pushed by the push plate or the like becomes flat even after being restored, and is a perfect circle over the entire circumference of the tube wall. Therefore, when joining a saddle branch joint or the like to the liner tube 1, there is a possibility that a gap may be formed in the joint portion and the joint may not be brought into close contact, resulting in poor joining. When joining the saddle branch joint to the liner pipe 1 inserted into the existing pipe, a hole is formed in the existing pipe so as not to damage the liner pipe, or the existing pipe at the branch portion is cut or crushed. Then, the saddle branch joint is directly joined to the liner tube 1.

A method of manufacturing the liner tube 1 for making the cross-sectional shape of the liner tube in the restored state a perfect circle is disclosed in Japanese Patent Application No. 11-157263 (B29C63 / 00). In this manufacturing method, a circular tube extruded from a mold is pulled down to form a circular tube having a small outer diameter.

When the diameter of the liner tube 1 is reduced, the pushed-in portion 1a pressed by a push plate or the like may be stretched by being bent in a substantially U-shape and may be reduced in thickness. Thickness t1 of other parts to thickness t2 of other parts
Than before. Thus, the push-in part 1
Japanese Patent Application No. 11-157262 discloses a method of manufacturing a liner tube in which a is formed into a thick wall so that the thickness after application is uniform.

[0006]

SUMMARY OF THE INVENTION However, Japanese Patent Application No.
Even with the liner manufacturing method disclosed in Japanese Patent No. 157263, it was not possible to restore the reduced-diameter pipe to a shape close to a perfect circle in the existing pipe.

[0007] Therefore, a main object of the present invention is to restore a reduced-diameter pipe so as to be sufficiently close to a perfect circle in an existing pipe, and to make the wall thickness uniform over the entire circumference. An object of the present invention is to provide a liner tube and a method for manufacturing the same.

[0008]

According to a first aspect of the present invention, there is provided a synthetic resin which can be deformed by pushing in a part in a circumferential direction after extrusion and which can be restored to a tube having a predetermined radius of curvature by heating and pressurizing the inside of the tube. A liner tube characterized in that the radius of curvature of the pushed-in portion during extrusion is smaller than a predetermined radius of curvature.

A second invention relates to a method of manufacturing a liner tube made of a synthetic resin which can be deformed by pushing in a part in the circumferential direction after extrusion and heating and pressurizing the inside of the tube to restore a tube having a predetermined radius of curvature. (A) A method of manufacturing a liner tube, characterized by extruding a pressed portion with a radius of curvature smaller than that of a restored curvature, and (b) deforming by pressing at a pressed portion.

[0010]

According to the first aspect of the present invention, when the pushed portion formed in a part of the tube wall is pushed inward in the radial direction, the pushed portion is deformed into a substantially U shape. When the inside of the deformed tube is heated and pressurized, portions other than the pushed portion of the tube wall have a predetermined radius of curvature, and the deformed pushed portion does not completely restore the original radius of curvature,
The predetermined radius of curvature is larger than the original radius of curvature. Accordingly, the entire circumference of the liner tube is restored so as to have a predetermined radius of curvature. The cross-sectional shape of the restored liner tube is a perfect circle or a circle sufficiently close to the perfect circle.

The pushed-in portion has a slightly reduced tube wall thickness when pushed in. However, by thickening the pushed-in portion in advance, the thickness of the tube wall of the liner tube at the time of restoration is completely reduced. It is uniform over the circumference, and it can be prevented that the strength is partially insufficient.

According to the second aspect of the present invention, it is possible to manufacture a liner tube in which the radius of curvature of the pressed portion is smaller than the radius of curvature after restoration. Like the liner tube of the first invention, this liner tube is restored so that the entire circumference has a predetermined radius of curvature, and the cross-sectional shape becomes a perfect circle or a circle sufficiently close to a perfect circle.

[0013]

According to the first aspect of the invention, the entire circumference of the liner tube is restored so as to have a predetermined radius of curvature, so that the liner tube can be made substantially circular. Thereby, the saddle branch joint and the like can be securely joined to the liner tube.

According to the second aspect of the present invention, it is possible to easily manufacture a liner tube that restores the entire circumference to a predetermined radius of curvature with a stable quality.

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

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A liner tube according to an embodiment of the present invention has a sectional shape as shown in FIG. 1 and is made of synthetic resin (polyethylene, polybutene, polypropylene, nylon, vinyl chloride, etc.). Shows an example in which the material is polyethylene. The method for manufacturing a liner tube according to one embodiment of the present invention is for manufacturing a liner tube 10 having a substantially heart-shaped cross section as shown in FIG. 1 (B). Specifically, as shown in FIG. This is performed using a simple manufacturing apparatus 12.

FIG. 1A shows a cross-sectional shape of a liner tube 10 formed by an extruder 14 provided in a manufacturing apparatus 12 and extruded through a base 16. FIG. 1B shows a cross-sectional shape of a reduced-diameter liner tube 10 manufactured and sent out by a manufacturing apparatus 12. And
FIG. 1 (C) shows the liner tube 1 inserted into the existing tube and restored by being heated and pressurized by steam from the inside.
0 shows the cross-sectional shape.

As shown in FIG. 1A, the extruder 14
The cross-sectional shape of the liner tube 10 extruded through the base 16 is oval, and a part of the tube wall in the circumferential direction is formed as a pressed portion 18 over a predetermined range. The radius of curvature R1 of the pushed-in portion 18 is smaller than the radius of curvature R2 of the other arc-shaped portions 20. Note that the pushed-in portion 18 and the arc-shaped portion 20 of the tube wall
The outer peripheral surface and the inner peripheral surface of the joint portion with are formed by gentle curved surfaces. The pushed-in portion 18 is formed as a thick portion, and its thickness t3 is larger than the thickness t2 of the arc-shaped portion 20.

The liner tube 10 extruded from the extruder 14 and shown in FIG.
The pressing portion 18 is pressed inward in the radial direction by the first forming roller 22 and the second forming roller 24 provided at the bottom, and the diameter is reduced to a substantially heart-shaped cross section as shown in FIG. Shape. At this time, push part 1
Reference numeral 8 denotes a bent portion of the tube wall deformed into a substantially U-shape, which is stretched and thinned with this deformation. As a result, the wall thickness becomes t2 over the entire circumference of the liner tube 10 and is made uniform. As described above, the wall thickness can be made uniform over the entire circumference of the liner tube 10, so that a partial lack of strength of the tube wall can be solved. The reason why the diameter of the liner tube 10 is reduced in this way is to reduce the insertion resistance to the existing tube.

Next, as shown in FIG. 1B, a procedure for repairing and renewing, for example, an existing aging pipe from the inside thereof using a liner pipe 10 whose diameter has been reduced to have a substantially heart-shaped cross section will be described. I do. The cross-sectional shape of the existing pipe is a perfect circle. The liner tube 10 whose diameter has been reduced is pressed and folded from the left and right directions in FIG. 1B so as to be convenient for transportation and storage. First, the folded liner tube 10 is heated to about 80 ° C., and inserted into the existing tube in this heated state. The reason why the liner tube 10 is heated at the time of insertion is that when the liner tube 10 is inserted into an existing tube or the like including a bent portion, the liner tube 10 is easily bent and the insertion resistance is reduced. The liner tube 10 is inserted in a heated state. In order to prevent the liner tube 10 from being restored to the original oval shape by this heating, the liner tube 10 is subjected to a diameter reducing process at a temperature near its melting point. .

Then, for example, a temperature of about 100 ° is inserted into the liner pipe 10 inserted into the existing pipe in a reduced diameter.
C (the temperature at which the melting point of the liner tube 10 is about 130 ° C. or less), and the pressure is about 0.18 MPa (a pressure at which the liner tube 10 does not burst, for example, 0.1 to 0.2 MPa).
The pressure of a is preferred. ) To supply steam. Then, as shown in FIG. 1 (C), the cross-sectional shape of the liner tube 10 is restored to a perfect circle or a circle sufficiently close to the perfect circle, and the entire outer peripheral surface of the liner tube 10 is restored in this restored state. Adhere to the entire inner peripheral surface of the existing pipe. Next, the supply of steam into the liner tube 10 is stopped and the liner tube 10 is naturally cooled, thereby completing the work such as repairing the existing tube. The thickness of the liner pipe 10 restored in the existing pipe is t2, and is uniform over the entire circumference.

The reason that the liner tube 10 is restored to a substantially perfect circle and the pushed-in portion 18 does not become flat as in the conventional liner tube 1 shown in FIG. The pushed-in portion 18 which is a bent portion of the tube wall is
This is because the original curvature radius R1 is not completely restored, but is restored to a predetermined curvature radius R2 larger than the original curvature radius R1. The radius of curvature R2 of the pushed-in portion 18 restored in this manner is the same as the radius of curvature R2 of the restored arc-shaped portion 20, so that the entire circumference of the liner tube 10 is a perfect circle with a predetermined radius of curvature R2 or sufficiently close to it. Restore to a circle. Thereby, the entire outer peripheral surface of the liner tube 10 can be completely adhered to the inner peripheral surface of the existing tube. Therefore, the saddle branch joint and the like can be securely joined to the liner tube 10.

The radius of curvature R1 of the pressed portion 18 before restoration shown in FIG.
Is determined in advance by a test, calculation, or the like so that the radius of curvature becomes R2. That is, for example, the curvature radius R2 of the pushed-in portion 18 after restoration is equal to the curvature radius R before restoration.
If it is 30% larger than 1, the pushed-in portion 18 may be formed at a radius of curvature R1 that is 30% or (30% + α%) smaller than the target radius of curvature R2 after restoration. Thereby, the liner tube 10 having the curvature radius R2 after the restoration can be obtained. α is a margin for preventing the radius of curvature of the pushed-in portion 18 after restoration from becoming larger than R2.

Next, a manufacturing apparatus 1 shown in FIG. 2 for manufacturing a liner tube 10 having a substantially heart-shaped cross section shown in FIG.
2 will be described. The manufacturing apparatus 12 includes an extruder 14, a first
A water tank 26, a second water tank 28, a take-off machine 30 and the like are included. The extruder 14 includes an extruder 34 for melting and extruding the polyolefin-based resin supplied from the hopper 32 by heating and extruding, and a tube molding die 36 is attached to an outlet of the extruder 34.

As shown in FIG. 3, the mold 36 includes a cylindrical die 38 and a mandrel 4 arranged inside the die 38.
0, a cylindrical molten resin passage 42 is formed between the inner surface of the die 38 and the outer surface of the mandrel 40. The inner peripheral surface of the die 38 and the outer peripheral surface of the mandrel 40 are shown in FIG.
As shown in (B), the cross-sectional shape perpendicular to each axial direction is formed in an oval shape. And mandrel 40
Since the lower part of the oval cross section has a small radius of curvature with a crescent-shaped lower part, the cross section of the molten resin passage 42 is wider at the lower part. Therefore, as shown in FIG. 4, the tube 10a extruded from the mold 36 has a thick portion (a portion to be the pushed portion 18) as the pushed portion 18 at the lower portion, and has an oval cross section.

The first water tank 26 is formed by processing a tube 10a having an oval cross section (see FIG. 4) extruded from the extruder 14 so as to be slightly thinner, and forming a liner tube 10 having an oval cross section (see FIG. 1).
(See FIG. 1A) to deform the liner tube 10 into a substantially heart-shaped cross-section and then cool it. As shown in FIG. 5, the first water tank 26 includes a main body 44 extending in the pushing direction of the pipe 10a. An inlet 46 of the tube 10a and an outlet 48 of the liner tube 10 are formed at one end and the other end in the longitudinal direction of the main body 44, and a plurality of openings 50 for maintenance and inspection are formed on the upper surface of the main body 44. A lid 52 is attached to each opening 50. The inner space of the main body 44 is
4, the first region 56 on the entrance 46 side includes:
The base 16 is arranged, the vacuum pump 58 is connected, and a diameter reducing device 62 and a plurality (two in this embodiment) of receiving rollers 64 are arranged in the second region 60 on the outlet 48 side. A watering pipe 66 (see FIG. 7) is arranged over the entire length of the first area 56 and the second area 60.

The base 16 includes a main body 16a having an oval cross section having an inner peripheral length substantially the same as the inner peripheral length of the existing pipe to be repaired or renewed by the liner pipe 10, and a flange on one end of the main body 16a. 16b is formed, and the collar 16b is
Attached to.

The diameter reducing device 62 is for deforming the liner tube 10 having an oval cross section shown in FIG. 1A so as to have a substantially heart-shaped cross section as shown in FIG. 1B. is there. As shown in FIG. 6, the diameter reducing device 62 deforms the first portion 68 defining the upper outer surface of the liner tube 10 having an oval cross section and the lower portion of the tube wall of the oval liner tube 10 into a substantially U-shape. And a second portion 70 for mounting. First part 68
Includes a main body 72 obtained by roughly dividing a cylindrical body in the axial direction,
A flange-shaped mounting portion 74 is formed at one end in the longitudinal direction of the main body 72, and a flat support portion 7 is formed at both ends in the circumferential direction of the main body 72.
6 are formed. Then, the bolt 7 is
8 is formed.

The second portion 70 is formed of a small-diameter first forming roller 2.
2 and a second forming roller 24 having a large diameter. The first forming roller 22 and the second forming roller 24 are arranged at a predetermined interval from each other in this order toward the front of the liner tube 10 in the extrusion direction.
Is arranged at a position higher than the upper part of the first forming roller 22. Then, the first forming roller 22 and the second
At the center of the forming roller 24, a support shaft 82 is provided, and each support shaft 82 is provided with a side plate 84 extending in the vertical direction.
And are rotatably supported. At the upper end of each side plate 84, a total of four support portions 86 extending in the horizontal direction are provided. Each support portion 86 is formed with a hole 88 for inserting a bolt 78. Then, a bolt 78 is inserted from below into the holes 80 and 88 of the support portions 76 and 86, 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.

As shown in FIG. 7, the receiving roller 64 receives the liner tube 10 whose cross-sectional shape has been changed (diameter reduced) into a substantially heart shape by the diameter reducing device 62, and further reduces the diameter thereof. And includes a roller body 94. The outer peripheral surface of the roller body 94 is formed as a pipe receiving portion 94a that is curved in a substantially U-shape when viewed from the extrusion direction of the liner tube 10. The roller body 94 is supported by a support shaft 94b, and the support shaft 94b is rotatably supported by the body 44 via a bearing (not shown).

The second water tank 28 is for further cooling the liner tube 10 cooled by the first water tank 26, and includes a main body 96 substantially similar to the main body 44 of the first water tank 26. A watering pipe is disposed inside the main body 96, and cooling water is sprayed from the watering pipe toward the liner pipe 10.

The take-up machine 30 is for taking the liner tube 10 at a constant speed, and includes a take-up roller 98 pressed against the lower and upper portions of the liner tube 10.
A rotating shaft of a motor (not shown) is connected to at least one of the take-off rollers 98, and the take-up speed of the liner tube 10 is adjusted by controlling the number of rotations of the motor.

When the liner tube 10 is manufactured using the manufacturing apparatus 12 shown in FIG. 2, first, as shown in FIG. 8, the nut 92 (see FIG. 6) in the diameter reducing device 62 is loosened to remove the second portion. Lower 70. Further, the pressure in the first region 56 of the first water tank 26 is reduced to a negative pressure by the vacuum pump 58, and cooling water (about 10 to 20 ° C.) is supplied to each of the water spray pipes 66 of the first water tank 26 and the second water tank 28. Supply). Then, the extruder 14 is driven to start extruding the oval tube 10a.

The tube 10 a having an oval cross section extruded from the extruder 14 passes through the base 16 of the first water tank 26 and is pressed against the inner surface of the base 16 by the negative pressure applied to the first region 56. When the tube 10a passes through the base 16, a cross-sectional shape smaller in size than the tube 10a is formed in the oval liner tube 10. The liner tube 10 is sent to the second region 60 while being cooled by the cooling water from the watering pipe 66. In the second region 60, the diameter reducing device 62
Of the second part 70 (the first and second forming rollers 22, 2)
4) is lowered so as not to contact the liner tube 10, so that the liner tube 10 is cooled without being deformed and the cross-sectional shape remains oval. When the liner tube 10 is extruded by a predetermined length, the dimensions and shape of the liner tube 10 are measured, and the manufacturing conditions (such as the melting temperature of the resin) are adjusted so that the dimensions and the like fall within an allowable range. The dimensions and shape of the liner tube 10 having an oval cross section are, as shown in FIG. 1A, the thickness of the pushed-in portion 18 is t3, its radius of curvature is R1, and the arc-shaped portion 20 other than the pushed-in portion 18 is formed.
Has a thickness t2 and a radius of curvature R2, and the manufacturing conditions are adjusted so as to have this dimension and the like.

When the dimensions of the liner tube 10 having an oval cross section are within an allowable range, the second portion 70 is lifted up while the extrusion of the tube 10 a by the extruder 14 is continued, and the liner tube 10 is placed under the liner tube 10. The first forming roller 22 and the second forming roller 24 are pressed. Then, the pushed-in portion 18 (see FIG. 1A) formed as a lower portion of the tube wall of the liner tube 10 having an oval cross section, that is, a thick portion, is fitted to the first forming roller 2
2 and the second forming roller 24 is stepwise pushed radially inward, and as shown in FIG. 1B, the pushed-in portion 18 is deformed into a substantially U-shape to obtain the substantially heart-shaped liner tube 10. . When the first and second forming rollers 22 and 24 are pressed against the pushed-in portion 18, the pushed-in portion 18 formed as a thick portion is stretched and its thickness is reduced to t2. Since it is formed thicker than the portion, that is, the arc-shaped portion 20, the thickness becomes t2 over the entire circumference of the liner tube 10 and becomes uniform.

The liner tube 10, whose diameter has been reduced by the diameter reducing device 62 and has a substantially heart-shaped cross section, is fed onto the receiving roller 64 while being cooled by cooling water. In each of the receiving rollers 64, the heat shrinkage of the liner tube 10 proceeds along the inner surface of the receiving portion 94a, so that the diameter of the liner tube 10 can be reduced efficiently without using any special means.

The liner tube 10 that has passed through the first water tank 26
Is further cooled by the second water tank 28 and then taken by the take-off machine 30. When the liner tube 10 having a predetermined length is taken by the take-off machine 30, a cutting device (not shown) is driven to cut the liner tube 10 to a predetermined length.

According to the method of manufacturing the liner tube 10 according to this embodiment, the liner tube 10 having an oval cross section (see FIG. 1A) is formed, and the pushed-in portion 18 formed as a thick portion is formed into a first portion. The tube wall including the pressed portion 18 is deformed into a substantially U-shape by being pressed by the first and second forming rollers 22 and 24. At this time, push part 1
The thickness of the liner 8 changes from t3 to t2, and the thickness of the liner tube 10 can be made uniform over the entire circumference. Therefore, the strength shortage of the pushed-in portion 18 can be resolved, and stable quality can be obtained.

As described with reference to FIG. 1, the liner pipe 10 having the reduced diameter manufactured by this manufacturing method is restored to a perfect circle in the existing pipe, and the inner circumference of the existing pipe is removed. It can be in close contact with the surface. The wall thickness of the liner tube 10 in this closely contacted state is made uniform over the entire circumference.

In order to accurately deform (reduce the diameter) the liner tube 10 having an oval cross section, it is necessary to appropriately set the temperature of the liner tube 10 passing through the diameter reducing device 62. As a means for adjusting the temperature, for example, a spacer 100 as shown in FIG. 9 may be used. The spacer 100 is a mounting plate 1 on which the diameter reducing device 62 is mounted.
02, a plurality of connecting rods 104 connecting the mounting plate 102 and the partition wall 54, the length of the connecting rod 104 is appropriately changed, and the position of the diameter reducing device 62 is adjusted. In the first water tank 26, since the temperature of the liner tube 10 decreases as it moves toward the front in the extrusion direction, when the mounting plate 102 is directly attached to the partition wall 54 without using the spacer 100, the liner tube 10 is Can be deformed at high temperature,
The longer the spacer 100 is, the lower the temperature can be.

Even when the spacer 100 is not used, the diameter reducing device 62 is connected to the second water tank 26 after the outlet 48 of the first water tank 26, and
The temperature at the time of diameter reduction processing of the liner tube 10 may be adjusted by attaching the liner tube 10 to the front of the inlet of the water tank 28 or inside the second water tank 28. In such a case, it is desirable that the first water tank 26 be maintained at a negative pressure without being divided into two.

In the above embodiment, the first embodiment shown in FIG.
The forming roller 22 and the second forming roller 24 are used to deform the liner tube 10 having an oval cross section into a substantially heart-shaped cross section. For example, as shown in FIG. The liner tube 10 may be deformed. The diameter reducing device 108 shown in FIG.
A portion 110 is provided. Since the first portion 68 is equivalent to that shown in FIG. 6, detailed description will be omitted. The second portion 110 has a forming plate 106. Formed plate 106
Is formed with an upper edge that is ascending in the direction toward the extrusion direction of the liner tube 10. The forming plate 106 pushes the pushed-in portion 18 of the tube wall of the liner tube 10 which is sequentially extruded by the upper edge portion inward in the radial direction, and substantially pushes the pushed-in portion 18 and the lower portion of the tube wall connected thereto substantially. It is for deforming into a letter shape. The forming plate 106 is provided at the center of the upper surface of the bottom plate 112. The bottom plate 112 is arranged at an upward slope in the direction toward the front of the liner tube 10 in the extrusion direction, and has a gradually narrowing width in the same direction. The bottom plate 112 has side plates 114 rising from both ends in the width direction.
Are formed, and a total of four support portions 86 extending in the horizontal direction from the upper end of the side plate 114 are formed. Each support 86
Is formed with a hole 88 for inserting a bolt 78. Then, a bolt 78 is inserted from below into the holes 88 and 80 provided in 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 110 is lowered, and when the nut 92 is tightened, the second portion 110 is raised.

Further, in the diameter reducing device 108 shown in FIG. 10, the liner tube 10 is deformed by one molding plate 106. For example, as shown in FIG. 11, a plurality of molding plates having different heights are formed. 116a, 116b, 1
16c and 116d may be provided on the upper surface of the bottom plate 112, and the liner tube 10 may be gradually deformed by these formed plates 116a to 116d.

Further, instead of the diameter reducing device 62 shown in FIG.
For example, a diameter reducing device 118 as shown in FIG.
May be used. In the diameter reducing device 118 shown in FIG. 12, the base portion of the first portion 122 is formed in a cylindrical shape, and the tip portion 124 is formed in the shape of an upper portion obtained by dividing the cylindrical body in half in the axial direction. I have. Further, a second portion 128 having a peak portion 126 is provided below the distal end portion 124. The diameter reducing device 120 shown in FIG. 13 is obtained by providing a second portion 130 instead of the second portion 128 in the diameter reducing device 118 shown in FIG. The second portion 130 includes a roller 132 that is rotatably supported. Also in these, the pushed-in portion 18 of the tube wall of the liner tube 10 can be pushed into the U-shape by the ridge 126 or the roller 132.

Further, as shown in FIG. 1 (A), the liner tube 10 has an oval cross section.
It may be elliptical (not shown). When the cross-sectional shape is an elliptical shape, one of the two curved portions having the smallest radius of curvature is formed as the pushed-in portion 18, and the thickness of the pushed-in portion 18 is shown in FIG. It is formed as a thick part like the pushed part 18 of the liner tube 10 shown. Then, the wall of the tube other than the pushed-in portion 18 is made to have a constant thickness smaller than the pushed-in portion 18.
As described above, the liner tube having the elliptical cross section operates in the same manner as the liner tube 10 shown in FIG. And the mold 3 of the manufacturing apparatus 12
6. The shape of the base 16, the first portion 68 of the diameter reducing device 62, and the like may be changed to manufacture a liner tube having an elliptical cross-section.

In the above embodiment, the inner peripheral surface of the die 38 of the mold 36 and the outer peripheral surface of the mandrel 40 are formed as shown in FIG.
As shown in (B), the cross-sectional shape perpendicular to each axial direction is formed in an oval shape. Instead, the cross-sectional shape of the inner peripheral surface of the die of the mold and the cross-sectional shape of the outer peripheral surface of the mandrel are changed. The liner tube 10 having an oval cross section can be formed by passing the tube extruded from the mold through a die 16 having an oval cross section on the inner peripheral surface. Furthermore, the cross-sectional shape of the inner peripheral surface of the die is circular,
The cross-sectional shape of the outer peripheral surface of the mandrel may be a shape in which the lower part of the circle is missing in a crescent shape, and the cross-section of the molten resin passage of this mold becomes wider at the lower part. According to the mold thus formed, the cross-sectional shape of the outer peripheral surface is circular,
It is possible to extrude a tube having a thick portion formed at a lower portion.
By passing the tube extruded from the mold through the base 16, the liner tube 10 having an oval cross section equivalent to that shown in FIG. 1A can be formed.

[Brief description of the drawings]

1A is a front view showing a state before a liner pipe according to an embodiment of the present invention is subjected to a diameter reducing process, and FIG. FIG. 1C is a front view showing the liner pipe after the application, and FIG. 1C is a front view showing the liner pipe after restoration in the embodiment of FIG.

FIG. 2 is a front view showing a manufacturing apparatus used for a method of manufacturing a liner tube according to one embodiment of the present invention.

3 (A) is a longitudinal sectional view showing a mold provided in the embodiment of FIG. 2, and FIG. 3 (B) is a sectional view taken along the line IIIB-IIIB in FIG. 3 (A).

FIG. 4 is a front view showing an oval-shaped tube extruded from a mold provided in the embodiment of FIG. 2;

5 (A) is a plan view showing a primary water tank provided in the embodiment of FIG. 2, and FIG. 5 (B) is a longitudinal sectional view showing the primary water tank of FIG. 5 (A).

6A is a front view showing a diameter reducing device provided in the embodiment of FIG. 2, and FIG. 6B is a side view showing the diameter reducing device of FIG. 6A.

FIG. 7 is a front view showing a roller and a liner tube provided in the embodiment in FIG. 2;

8 is a longitudinal sectional view showing a state where a second portion of the diameter reducing device provided in the embodiment of FIG. 2 is lowered.

9 is a longitudinal sectional view showing a state in which the position of the diameter reducing device provided in the embodiment of FIG. 2 has been changed.

10A is a front view showing a modification of the diameter reducing device provided in the embodiment of FIG. 2, and FIG. 10B is a side view showing the diameter reducing device of FIG. 10A.

FIG. 11A shows a second example of the diameter reducing device provided in the embodiment of FIG. 2;
FIG. 11B is a plan view showing a modification of the portion, FIG. 11B is a front view of the second portion in FIG. 11A, FIG. 11C is a left side view of the second portion in FIG. 11A, and FIG. It is a right view of the 2nd part of (A).

12 (A) is a perspective view showing a modification of the diameter reducing device provided in the embodiment of FIG. 2, and FIG. 12 (B) is an exploded perspective view showing the diameter reducing device of FIG. 12 (A).

FIG. 13 is a perspective view showing a modification of the diameter reducing device provided in the embodiment in FIG. 2;

14 (A) is a front view showing a state before the conventional liner tube is subjected to diameter reduction processing, and FIG. 14 (B) is a state in which the conventional liner tube of FIG. 14 (A) is subjected to diameter reduction processing. FIG. 14C is a front view showing a state after the restoration, and FIG. 14C is a front view showing a state after the restoration of the conventional liner tube of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Liner tube 10a ... Tube 12 ... Manufacturing apparatus 14 ... Extrusion molding machine 16 ... Ling 18 ... Push-in part 20 ... Arc-shaped part 22 ... First molding roller 24 ... Second molding roller 26 ... First water tank 30 ... Pull-off machine 36 ... Mold 62 ... Diameter

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // B29L 23:00 B29L 23:00 (72) Inventor Hideki 64 64 Ishizukitamachi, Sakai-shi, Osaka Inside Kubota Vinyl Pipe Factory (72) Inventor Takachi Harada 64 Ishizu-Kitamachi, Sakai City, Osaka Prefecture Inside Kubota Vinyl Pipe Factory, Inc. Inventor Hiroyuki Maebane 4-1-2, Hirano-cho, Chuo-ku, Osaka-shi Inside Osaka Gas Co., Ltd. (72) Inventor Masahiro Yamada 4-1-2, Hirano-cho, Chuo-ku, Osaka-shi Osaka Gas Co. 3H111 AA04 BA15 DB17 EA04 EA18 4F207 AA04 AA11 AA12 AA15 AA29 AG09 AG21 AH43 AH46 KA01 KA17 KA20 KW26 KW41 4F211 AD12 AG08 AH43 SA13 SC03 SD04 SG01 SH18 SJ01

Claims (4)

[Claims] 1. A liner tube made of a synthetic resin which can be deformed by being pushed in at a part in the circumferential direction after extrusion, and can be restored to a tube having a predetermined radius of curvature by heating and pressurizing the inside of the tube. A liner tube having a radius smaller than the predetermined radius of curvature. 2. The liner tube according to claim 1, wherein the cross-sectional shape at the time of extrusion is an oval shape, and the minimum radius of curvature portion is pushed in. 3. The push-in portion according to claim 1, wherein said push-in portion is made thick.
Or the liner tube according to 2. 4. A method for producing a liner tube made of a synthetic resin which can be deformed by pushing in a part in a circumferential direction after extrusion and heating and pressurizing the inside of the tube to restore a tube having a predetermined radius of curvature. A method of manufacturing a liner tube, comprising: extruding a pressed portion with a radius of curvature smaller than the restored radius of curvature, and (b) deforming by pressing in at the pressed portion.