JPH09314638A - Manufacture of synthetic resin tube for lining existing tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the fusing strength of a re-fused surface so as not to develop cracks due to the expansion at softening under heat by a method wherein a resin material is once divided into branch flows and then met again so as to be integrally fused together by providing a large number of resin branch flow holes in the annular resin flow passage of a circular die. SOLUTION: A fused synthetic resin material passes through resin branch flow holes 5 inclining axially by a predetermined angle in a circular die, resulting in applying a part of the back pressure being applied to the axial direction of the circular die in an extruder to a re-fused surface 7 locating just after the passing of the resin material through the holes as a partial pressure so as to be turned into a synthetic resin tube 6 for lining an existing tube having the strength equivalent to that of the other part by improving the fusing strength of the resin material and making the fusing integration more stronger. In addition, in the re-fused surface 7, which is obtained through the division into the branch flows by a large number of the resin branch flow holes and then the strong re-fusion of the branch flows, a large number of cell-like walls 8 under densely aggregated state are formed. Further, by being connected cell-like walls 8 adjacent to each other with each other, the walls formed in zigzags to the direction of the thickness of the wall, resulting in remarkably increasing the proof capability to external stress.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method of manufacturing a synthetic resin pipe for an existing pipe lining.

[0002]

2. Description of the Related Art In recent years, for repairing or reinforcing an existing pipe buried underground or in the structure of a building, which constitutes a conduit for laying cables such as power wiring and communication wiring, the inner surface of the pipe is repaired and reinforced. A lining construction method has been developed in which a synthetic resin pipe is inserted into and installed in a lined state. For example, Japanese Patent Laid-Open No. 1-298582.
As disclosed in Japanese Patent Publication No. 8, a thermoplastic synthetic resin pipe having an outer diameter smaller than the inner diameter of an existing pipe is inserted in a heated state, and then pressurized steam is introduced into the resin pipe to apply an internal pressure to the resin. The pipe is expanded in the radial direction, brought into close contact with the existing pipe, and then cooled and solidified.

The synthetic resin pipe for lining used in the lining method as described above is manufactured by an extrusion molding method. For example, a synthetic resin such as polyvinyl chloride resin is heated and kneaded in an extruder and then extruded. A so-called synthetic resin extrusion molding method is generally used in which a continuous die is formed by using a round die installed at the tip of a machine.

However, the synthetic resin pipe for lining an existing pipe manufactured by such a conventional manufacturing method has a structure in which an inner surface of the existing pipe is heated and softened by the pressurized steam introduced into the pipe during lining. There is a problem that the temperature of the contact portion and the drain accumulation portion is lowered, and a temperature difference from the other portions is generated, resulting in non-uniform expansion, and cracks called so-called bursts occur on the pipe wall. In many cases, such cracks are generated along the surface where the synthetic resin diverted by the spider of the round die at the time of its production is reassembled and fused.

The above-mentioned crack-causing part is a circular die (21) shown in FIG. 4 (a) as a typical known example.
As a so-called scar by the Spider (22) of Fig.
As shown in (b), the re-fusion surface (27) continuously appears in the substance of the synthetic resin pipe (26) in the pipe axial direction. Then, the re-fusion surface (27) becomes inferior in strength to the other portions, and moreover, it continuously appears from the inner surface of the pipe to the outer surface of the pipe, so that external stress is applied to the synthetic resin pipe (26). , Cracks are likely to occur in this part. Especially when the synthetic resin pipe (26) is heated and softened and the internal pressure of the pipe is increased for the purpose of expanding the synthetic resin pipe (26) like the lining synthetic resin pipe, cracks on the re-fusion surface (27) are more likely to occur. Cheap.

In order to solve this point, similarly, as a well-known round die, for example, the spider (32) is deformed like a spiral arm like the round die (31) shown in FIG. A circular die (41) shown in FIG. 6 (a), which uses a perforated plate (42) in which two or more rows of inner and outer rows of resin distribution holes are arranged in concentric circles with a circular cross section in a portion corresponding to the spider, is known. ing.

In the round die (31) shown in FIG. 5 (a),
Although the synthetic resin pipe (36) in the state shown in Fig. 5 (b) is obtained, and the re-fusion surface (37) is continuous from the pipe inner surface to the pipe outer surface, its length increases the pipe thickness. Since it appears in a state in which it is inclined in the tangential direction of the pipe circumference, the resistance to external stress increases more than that shown in Fig. 4, but due to insufficient flow of synthetic resin in the narrow corner (P) of the base of the spider (32). Then, the substantial part of the synthetic resin pipe (36) separated by the re-fusion surface (37) becomes thin near the inner and outer surfaces of the synthetic resin pipe (36), and as a result, it becomes a point of concentration of external stress.
Not enough solution for crack prevention.

Further, in the round die (41) shown in FIG. 6 (a), a synthetic resin pipe (46) in the state shown in FIG. 6 (b) is obtained, and its re-fusion surface (47) has a large number of parts. Although the cell walls (48) are densely packed and continuous from the inner surface of the tube to the outer surface of the tube, they appear in a zigzag shape in the thickness direction, so that the proof stress against external stress increases more than that shown in FIG. As expected, this also results in an increase in the number of poorly rebonded surfaces (47), which again does not provide a satisfactory overall solution.

The inventors of the present invention have conducted extensive research in the background of such conventional circumstances, and as a result, in the production of synthetic resin pipes for existing pipe linings, the molten state in the extruder is the same as in the conventional pipe production. The synthetic resin material thus prepared is pressed in one direction along the axial direction of the round die, and the synthetic resin material is diverted by a spider to be assembled and fused again. The pressure is not sufficient for re-fusion, and even if the re-fusion surface is increased unnecessarily in such a state, a synthetic resin pipe of the same kind with resistance to cracks due to external stress cannot be obtained. In order to split and reassemble by using a spider, it is necessary to increase the re-fusion surface and at the same time increase the pressure in the direction of the fusion surface required for fusion integration to increase the fusion strength. Focused on, and completed this invention

[0010]

That is, the present invention provides:
Against the above background, when manufacturing a synthetic resin pipe for an existing pipe lining by using an extruder with a round die, the synthetic resin material is diverted in the round die and reassembled to be fused together. Manufacture to obtain a synthetic resin pipe for an existing pipe lining that has excellent fracture strength and does not crack when expanded due to heat softening during lining by increasing the fusion strength of the re-fusion surface The purpose is to provide a method.

[0011]

Based on the above-mentioned object, the present invention is to manufacture a synthetic resin pipe for an existing pipe lining, in which a synthetic resin material is extruded into a pipe shape by using an extruder with a round die. In the method, in the annular resin flow path of the round die, a large number of resin shunt holes having a circular cross section having an axial direction of a predetermined angle with respect to the axial direction of the round die are at least two rows inside and outside, Between adjacent rows, it is assumed that annular porous members provided in a zigzag arrangement are mutually arranged, the synthetic resin material is once diverted through the resin diverting hole, and then reassembled until reaching the die outlet. A gist of the present invention is a method for manufacturing a synthetic resin pipe for an existing pipe lining, which is characterized by extruding into a pipe shape by fusing and unifying.

In the present invention, the resin distribution holes provided in at least two rows inside and outside the annular porous member are usually
The outer row has a larger diameter than the inner row.

Further, in the present invention, the annular porous member is within a range of 20 to 60 degrees with respect to the axial direction of the round die, and the odd-numbered rows and the even-numbered rows are in the same direction at a predetermined angle. The resin distribution hole having the axial direction may be provided.

Further, in the present invention, the annular porous member is in the range of 20 to 60 degrees with respect to the axial direction of the round die, and the odd-numbered rows and the even-numbered rows have different axial directions. It is possible to provide a resin diversion hole having

The present invention will be described below with reference to the drawings showing the embodiments.

That is, as shown in FIG. 1, a method for manufacturing a synthetic resin pipe for an existing pipe lining of the present invention is such that a synthetic resin material (M) is heated and melted by an extruder (E) to be kneaded, and then a round die is used. Pipe shape (k) continuously using (1)
The method of extrusion molding is adopted.

The circular die (1) has an annular porous member (f) in an annular resin flow channel (f) formed by being surrounded by an outer die (3) and an inner die (4) as shown in FIG. 2) is arranged. The annular porous member (2) is usually sandwiched by the outer molds (3a), (3b) at its peripheral edge and by the inner molds (4a), (4b) at its central portion, and the annular porous member (2) itself is a cyclic resin. The resin distribution channel is formed in the channel (f), and it also functions as a so-called perforated plate spider that supports the inner mold (4).

As shown in FIG. 3 (a), a large number of resin distribution holes (5) having a circular cross section are provided in at least two rows inside and outside of the annular porous member (2) where the resin distribution channels are formed. The resin flow-dividing holes (5) are provided in a zigzag arrangement with respect to each other between adjacent rows. And this resin flow-dividing hole (5) is the axial direction (x-) in the AA line cross section of the 1st row (L ₁ ) illustrated in FIG. 3B.
x) is formed so as to be different from the axial direction (d-d) of the round die (1) and has a predetermined angle (α) in the tangential direction of the annular resin flow path.

Further, the embodiment of the resin distribution hole (5) is as follows.
As shown in FIG. 3B, all the columns (L ₁ ) to (L ₃ ) have a predetermined angle (α) in the same direction, and odd-numbered columns and even numbers having the predetermined angle (α). The columns may have different positive and negative directions, the odd columns and the even columns may have mutually different predetermined angles, or a combination thereof may be adopted.

The predetermined angle of the resin diversion hole (5) is within the range of 20 to 60 degrees in the tangential direction of the annular resin flow path with respect to the axial direction of the round die (1). When the predetermined angle (α) is less than 20 degrees, when the synthetic resin material (M) in a molten state is split, reassembled and fused, the re-fusion surface (7) required to increase the fusion strength is required. When the pressure is insufficient, sufficient fusion and integration cannot be achieved, and when it exceeds 60 degrees, the synthetic resin material (M) has an increased flow resistance, and the extrusion operation becomes difficult. Therefore, the predetermined angle is preferably 30
~ 45 degrees.

According to the present invention, the molten synthetic resin material (M) passes through the resin diversion hole (5) having an axial direction of a predetermined angle in the round die (1), so that the round die ( A part of the back pressure in the extruder applied in the axial direction of 1) acts as a partial pressure on the re-fusion surface (7) immediately after passing, so that the fusion strength is increased and the fusion integration becomes stronger. The synthetic resin pipe (6) for the existing pipe lining has a strength comparable to the other parts. Moreover, as shown in FIG.
The re-fusion surface (7) obtained by dividing and re-sealing firmly by a large number of resin distribution holes (5) has a large number of cellular walls (8).
Are formed in a dense state, and adjacent cell-shaped walls (8) are connected to each other to appear in a zigzag shape in the thickness direction, so that the proof stress against external stress is significantly increased. Therefore, the existing synthetic resin pipe for pipe lining (6) obtained according to the present invention has a high proof stress against cracks due to external stress at the time of heat softening and expansion during lining construction. The present invention can be applied not only to a synthetic resin pipe for an existing pipe lining to be subjected to processing accompanied by heating and expansion, but also to a final synthetic resin pipe product that is normally used at room temperature. Needless to say.

[0022]

Embodiments of the present invention will now be described with reference to the drawings along with comparative examples.

First, as an apparatus for producing a synthetic resin pipe for an existing pipe lining, as shown in FIG. 1, an extrusion molding apparatus in which a round die (1) was attached to an extruder (E) was prepared.

The extruder (E) has a screw diameter of 55 m.
m, L / D = 18 different-direction twin-screw extruder is used, and the circular die (1) is the one shown in FIG. 2 and the annular porous member (2) is the resin shunt of the embodiment shown in FIG. 3 (a). The one having holes (5) was used.

Here, the annular porous member (2) has a thickness of 50.
mm, and the resin diversion hole (5) was located in the annular resin flow path (f) having an outer diameter of 170 mm and an inner diameter of 125 mm centered on the axis of the round die (1). Furthermore, the resin distribution holes (5) were arranged in three rows inside and outside, and the diameters were set to 8 mm, 7.5 mm, and 7 mm from the outermost row, and the predetermined angle was provided in the direction of 45 degrees. The opening ratio of the resin distribution hole (5) to the annular resin flow channel (f) was set to 50%.

Next, as a synthetic resin material, 100 parts by weight of polyvinyl chloride resin, 1.5 parts by weight of octyltin mercapto, 1 part by weight of acrylic processing aid, 1.5 parts by weight of lubricant, 0.3 parts by weight of titanium oxide. Was prepared, and after mixing these, the mixture was put into the extrusion molding device, kneaded by heating, and molded into a pipe having a diameter of 150 mm and a thickness of 3 mm.

A sample having a length of 2 m was sampled from the pipe obtained as described above, and two kinds of tests were carried out for pressure resistance. The test method is as follows.

-Test Method-Test 1: Using the test apparatus shown in FIG. 7, a cap (C1) provided with a pressurized water introduction pipe (51) and a cap provided with a drain pipe (52) were provided at both ends of the sample (T). The water at a temperature of 20 ° C. is fed into the sample (T) from the water pressure pump (m) which is sealed with (C2) and is connected to the pressurized water introducing pipe (51), and the rising speed of the water pressure inside the sample (T) is increased. The water pressure at the time of breaking of the sample (T) was measured by setting the pressure at 1 kgf / cm ² per minute and setting the maximum water pressure within 20 kgf / cm ² .

Test 2: In the test apparatus shown in FIG. 7, an iron pipe with an inner diameter of 225 mm was attached to the outside of the sample (T) with caps (C1) and (C2) (not shown), and in this state, 0.1 kgf / cm The pressurized steam of ² was introduced for 20 minutes, and then the pressurized steam was pressurized at a rate of 0.1 kgf / cm ² per minute and kept at 0.5 kgf / cm ² .
The sample (T) was expanded in a heat-softened state, and the state of crack generation was observed within 1 hour from the time when it was confirmed that the sample (T) was pressure bonded to the iron pipe. The sample (T) in Test 2
The expansion ratio is 1.5 times in the radial direction.

According to the test results of the pipes obtained in the examples, in Test 1, there was no fracture until the water pressure reached a maximum of 20 kgf / cm ^2, and in Test 2, neither rupture nor any cracks occurred.

COMPARATIVE EXAMPLE 1 Except that the spider (22) shown in FIG. 4 (a) has the same shape as the spider (22) shown in FIG. Got a pipe.

Taking a sample from the pipe obtained above,
A pressure resistance test was conducted in the same manner as in the example. As a result, in Test 1, the sample broke at a water pressure of 16 kgf / cm ² . Further, in Test 2, 35 minutes after the sample was pressure-bonded to the iron pipe, cracks elongated in the length direction and occurred in a state of penetrating from the sample inner surface to the sample surface.

Comparative Example 2 A round die used for manufacturing has a shape as shown in FIG. 6 (a), and the resin diversion hole has an axial direction coinciding with the axial direction of the round die. Except for the above, a pipe having the same outer shape was obtained by the same manufacturing method as that of the example.

Taking a sample from the pipe obtained above,
A pressure resistance test was conducted in the same manner as in the example. As a result, in Test 1, the sample broke at a water pressure of 18.5 kgf / cm ² . In test 2, 45 minutes after the sample was pressed onto the iron pipe,
Countless cracks were generated, and one of them cracked on the sample surface.

Comparative Example 3 A pipe was manufactured in exactly the same manner as in the example except that the resin diversion holes of the round die used in the example had an axial direction of 70 degrees with respect to the axial direction of the round die. I tried to mold.
However, the synthetic resin stayed in the vicinity of the inlet of the resin diversion hole of the round die and caused thermal decomposition, so that the pipe could not be molded.

[0036]

As described above, according to the present invention, in the annular resin flow path of the round die used in the conventional method for producing a synthetic resin pipe, the annular resin flow is made in the axial direction of the round die. Arrangement of a plurality of resin shunt holes having a circular cross section having an axial direction of a predetermined angle in the tangential direction of the passage in at least two rows inside and outside, and in a zigzag arrangement between adjacent rows. Since the round die is used, the fusion and integration of the re-fusion surface immediately after passing through the resin distribution hole becomes strong, and in addition, the re-fusion which is divided by a large number of resin distribution holes and re-bonded firmly The fusion surface is formed in a state in which a large number of cellular walls are densely packed, and adjacent cellular walls are connected to each other and appear in a zigzag shape in the thickness direction. Made of strong synthetic resin pipe There is an effect that can be. Therefore, the existing synthetic resin pipe for a pipe lining obtained by the present invention has an effect that it has a high proof stress against cracks due to external stress at the time of softening and expanding during lining.

[Brief description of drawings]

FIG. 1 is a schematic view showing a manufacturing apparatus for manufacturing a synthetic resin pipe for an existing pipe lining, which is adopted in the present invention.

FIG. 2 is a cross-sectional view showing a round die used in the present invention.

3 is a drawing showing the annular porous member shown in FIG. 2, and FIG. 3 (a) is an axial plan view of a round die, FIG.
(B) is a cross-sectional view taken along the line AA showing the aspect of the resin distribution holes, FIG.
(C) is an enlarged partial cross-sectional view of an existing synthetic resin pipe for pipe lining.

FIG. 4 is a cross-sectional view showing a conventional round die used for producing a pipe and a synthetic resin pipe produced by this round die, and FIG. 4 (a) is a cross-sectional view showing the round die. 4 (b) is an enlarged partial view of a cross section of the synthetic resin pipe.

FIG. 5 is a cross-sectional view showing another conventional round die used for manufacturing a pipe and a synthetic resin pipe produced by this round die, and FIG. 5 (A) is a cross section showing the round die. FIG. 5 (B) is an enlarged partial view of the cross section of the synthetic resin pipe.

FIG. 6 is a cross-sectional view showing another conventional round die used for producing a pipe and a synthetic resin pipe produced by this round die, and FIG. 6 (a) shows the round die. A sectional view and FIG. 6B are enlarged sectional views of the synthetic resin pipe.

FIG. 7 is a schematic view showing a test apparatus used for a pressure resistance test of the samples obtained in the examples and the comparative examples.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Round die 2 ... Annular porous member 3 ... Outer die 4 ... Inner die 5 ... Resin diversion hole 6 ... Existing pipe lining synthetic resin pipe 7 ... Re-fusion surface 8 ... Cellular wall E ... Extruder M ... Synthesis Resin material f ... Annular resin flow path

Claims (4)

[Claims] 1. A method for manufacturing a synthetic resin pipe for an existing pipe lining, comprising extruding a synthetic resin material into a pipe shape by using an extruder with a round die, wherein the annular resin flow path of the round die is provided with A large number of resin shunt holes with a circular cross section having an axial direction at a predetermined angle in the tangential direction of the annular resin flow path with respect to the axial direction of the round die are provided in at least two rows inside and outside, and between adjacent rows. It is assumed that the annular porous members provided in a zigzag arrangement are arranged in the pipe, the synthetic resin material is once diverted through the resin diverting hole, and then the dies are reassembled and fused and integrated by the time it reaches the die outlet to form a pipe. A method for producing a synthetic resin pipe for an existing pipe lining, which comprises extruding into a tubular shape. 2. A resin in which an annular porous member is within a range of 20 to 60 degrees with respect to an axial direction of a round die, and odd-numbered rows and even-numbered rows have axial directions of a predetermined angle in the same direction. The method for producing a synthetic resin pipe for an existing pipe lining according to claim 1, wherein a diversion hole is provided. 3. The annular porous member is within a range of 20 to 60 degrees with respect to the axial direction of the round die, and the odd-numbered rows and the even-numbered rows have axial directions of predetermined angles in different positive and negative directions. The method for producing a synthetic resin pipe for an existing pipe lining according to claim 1, wherein a resin diversion hole is provided. 4. An annular porous member is provided with a resin distribution hole having an axial direction in which the odd-numbered rows and the even-numbered rows have different axial directions within a range of 20 to 60 degrees with respect to the axial direction of the round die. The method for producing a synthetic resin pipe for an existing pipe lining in the axial direction of the existing round die according to claim 2 or 3, which is provided.