JP2004114359A - Coated pipe, method for manufacturing coated pipe and coated pipe manufacturing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coated pipe with a foam layer highly expanded uniformly on the outer periphery of a pipe and a method for efficiently manufacturing the coated pipe by which the uniformly highly expanded foam layer is formed on the outer periphery of the pipe and a skin layer is laminated on the outer periphery. <P>SOLUTION: This method for manufacturing the coated pipe comprises a slitting step of continuously slitting a foamed tube longitudinally while supplying the foamed tubes which become the foam layer in succession, a pipe inserting step of inserting the pipe into the foamed tube from the slit while expanding the diameter of the slit foamed tube, a foamed tube diameter contracting step of contracting the diameter of the foamed tube into which the pipe is inserted and a skin layer forming step of forming the skin layer on the outer periphery of the foamed tube with the contracted diameter into which the pipe is inserted. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a coated pipe in which a foam layer is formed on a pipe surface, and further, a skin layer is formed on the outer periphery of the foam layer, and a method for manufacturing the coated pipe.
[0002]
[Prior art]
Conventionally, pipes, for example, synthetic resin pipes, copper pipes, steel pipes, etc., for the purpose of imparting performance such as dew proofing, heat insulation, sound insulation, etc., the outer periphery of the pipe with a foam layer molded from a foamed synthetic resin composition. Coated coated pipes are used.
[0003]
However, since the foam layer has low frictional strength and scratching strength, there is a problem that when the foamed layer is exposed to the outside, the foam layer is easily damaged by friction or scratching during construction or after piping.
[0004]
In order to protect the surface of the foam layer, a foam layer having a skin layer formed of a non-foamed synthetic resin on the outer peripheral surface has been proposed.
[0005]
For example, Japanese Patent Application Laid-Open No. S61-293825 discloses a method for manufacturing an insulated pipe having a foam layer formed on a pipe surface and a skin layer formed on the outer periphery of the foam layer using an extruder. I have. In this production method, a long land die is used as a die of an extruder, and a foam layer forming composition and a skin layer forming resin are supplied to an extruder head to pipe the foam layer and the skin layer. It is disclosed that the foamed synthetic resin composition is foamed in a long land die and cooled at the same time by extrusion molding on the outer periphery of the resin.
[0006]
[Problems to be solved by the invention]
However, in the manufacturing method disclosed in JP-A-61-293825, foaming is performed in a long land die and cooling is performed in the long land die. And the inner surface of the long land die is cooled by the inside of the long land die while foaming is restricted, and the shape is fixed.
[0007]
Therefore, when a thermal decomposition type chemical foaming agent is used, the gas is cooled before the thermal decomposition is completely performed, so that the gas pressure of the foaming agent dissolved in the resin becomes low, and the expansion ratio becomes twice. Only something of the degree was obtained. Also, even when using a physical foaming agent, when the resin composition of the foam layer foams in a state where foaming in the thickness direction is regulated by the long land dice and the pipe, and when coming out of the long land dice, Since the foam layer was covered with the skin layer fixed by cooling, a foam having a high expansion ratio could not be obtained.
[0008]
Further, since the conventional heat insulating pipe is formed by simultaneously extruding the foam layer and the skin layer on the outer periphery of the pipe, the foam layer is in close contact with the entire outer peripheral surface of the pipe, and a plurality of heat insulating pipes are formed. Is required to peel off the foam layer at the end of the heat-insulating pipe. However, there is a problem that the peeling work is difficult to perform because the foam layer adheres too closely to the outer peripheral surface of the pipe.
[0009]
The present invention solves a problem in a method for manufacturing a coated pipe having a foam layer and a skin layer, and forms a highly foamed foam layer uniformly on the outer periphery of the pipe while removing the pipe from the pipe. In addition to providing a coated pipe that can easily perform the peeling operation of the foam layer, it is also possible to efficiently form a coated pipe in which a highly foamed foam layer can be formed on the outer circumference of the pipe and a skin layer is further coated on the outer circumference. The aim is to provide a method.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 is a coated pipe in which a foam layer is formed on a pipe surface, and further, a skin layer is formed on an outer periphery of the foam layer. The skin layer is formed in a cylindrical shape and has a cut extending in the longitudinal direction, and the skin layer has continuous continuity extending in the longitudinal direction.
[0011]
As the pipe used in the present invention, for example, a pipe having sound insulation, dew-proof, heat insulation, for example, a metal pipe such as a steel pipe, a copper pipe, or a polyolefin pipe such as polyethylene, polypropylene, and polybutene-1, Synthetic resin pipes such as crosslinked polyolefin pipes such as crosslinked polyethylene.
[0012]
Further, the foam layer coated on the outer periphery of the pipe is made of a foamed resin composition containing a thermoplastic resin that can be foamed in a low pressure zone by a foaming agent. Examples of the thermoplastic resin include polyethylene, polypropylene, polystyrene, and chloride. Extrudable thermoplastic resins such as vinyl, vinylidene chloride, ethylene-vinyl acetate copolymer, chlorinated polyethylene, ethylene-propylene copolymer, ethylene-ethyl acrylate copolymer, polyethylene terephthalate, ABS resin, and acrylic resin. These may be used alone or in combination of two or more.
[0013]
The expansion ratio of the foam layer is preferably 5 times or more. If it is smaller than 5 times, the thermal conductivity is apt to decrease, and if it is 5 times or more, the heat insulation / dew-proof performance is remarkably improved. Also, as for the sound insulation performance, when the foaming ratio is 5 times or more, the sound absorbing effect is enhanced.
As the cell diameter of the foam layer, the smaller the cell diameter, the lower the thermal conductivity and the better the heat insulation / dew-proof performance, but the higher the expansion ratio, the larger the cell diameter inevitably. Therefore, preferably 50 μm to 4 mm . If it is larger than 4 mm, convection of heat is generated in the bubbles and the thermal conductivity increases, so that the heat insulation / dew-proof performance is reduced.
Further, when the open cell ratio defined by ASTM D2856 is high, the thermal conductivity increases, and the heat insulation / dewproofing performance is reduced. Therefore, when used for heat insulation / dewproofing applications, 0 to 30% is preferable.
On the other hand, when used for sound insulation, a high open cell ratio is excellent in sound absorbing effect, so that it is preferably 30% or more. This is because the higher the open cell ratio, the more easily sound passes through a complicated path in the foam layer and is converted into thermal energy when the sound enters the foam layer. In addition, since the skin layer is covered, the sound incident on the foam layer passes through a complicated path, is reflected by the skin layer, and passes through the complicated path again, so that the sound is more effectively heated. It is converted to energy and absorbed.
[0014]
The skin layer coated on the outer periphery of the foam layer is preferably an extrudable resin, and is preferably a scratch-resistant thermoplastic resin. In addition, desired performance can be imparted by blending various additives. For example, by adding calcium carbonate, barium sulfate, or the like to a thermoplastic resin, the specific gravity of the skin layer increases, and sound insulation performance can be effectively provided.
[0015]
According to the first aspect of the present invention, the foam layer is formed in a cylindrical shape, and a cut extending in the longitudinal direction for inserting the pipe into the tube is formed. Since the continuous skin layer is formed on the outer periphery, the foam layer is removed from the pipe at the axial end of the covered pipe, such as connection work between the covered pipes, while the foam layer is uniformly foamed. When it is necessary, since the foam layer can be easily peeled from the cut portion, the connection work of the coated pipe is also facilitated.
[0016]
According to a second aspect of the present invention, in the invention of the coated pipe according to the first aspect, a cut extending in a longitudinal direction of the foam layer is intermittently fused. .
Intermittent fusion means that there is a portion that is fused along a cut and an unfused portion.
[0017]
According to the second aspect of the present invention, since the cuts of the foam layer are intermittently fused, it is possible to prevent the cuts from being opened at the time of forming the skin layer in the fused portion. The peeling of the foam layer from the pipe in the unfused portion of the cut can be easily performed.
[0018]
The invention according to claim 3 is a method for manufacturing a coated pipe in which a foam layer is formed on a pipe surface and further a skin layer is formed on the outer periphery of the foam layer. A slit forming step of continuously forming a cut in the foam tube in the longitudinal direction of the foam tube while continuously supplying the pipe, and a pipe inserting step of inserting a pipe into the foam tube from the cut while expanding the diameter of the cut foam tube. Producing a coated pipe by a foam tube reducing step of reducing the diameter of the foam tube in which the pipe is inserted, and a skin layer forming step of forming a skin layer on the outer periphery of the foam tube in which the pipe is inserted and reduced in diameter. It is characterized by the following.
[0019]
As means for supplying the foamed tube, a foamed tube to be a foam layer manufactured in advance may be wound on a reel or the like and supplied to the slit forming step, or a foamed tube manufacturing step may be provided. Alternatively, the manufactured foam tube may be directly supplied to the slit forming step.
[0020]
According to the third aspect of the present invention, a series of processes for manufacturing a coated pipe can be performed in-line, and the cooling by the outer diameter-regulating mold is rate-determined as in the prior art, thereby reducing the production speed. There is no problem that it cannot be raised, and the coated pipe can be manufactured efficiently.
[0021]
According to a fourth aspect of the present invention, in the method for manufacturing a covered pipe according to the third aspect, the slit forming step includes a foam tube manufacturing step of extruding the foam tube for continuously supplying the foam tube. It is characterized by doing.
As described above, the foam layer coated on the outer periphery of the pipe is made of a foamed resin composition containing a thermoplastic resin that can be foamed in a low-pressure zone with a foaming agent. When the cell nucleating agent is added in an amount of 2 to 3 parts by weight with respect to 100 parts by weight of the thermoplastic resin, the cell diameter of the obtained foam becomes fine, and the sound insulation, dew-proof and heat insulation performances are improved.
[0022]
According to the invention as set forth in claim 4, the foam layer covering the surface of the pipe is not directly formed on the outer surface of the pipe, but only the foam tube to be the foam layer is manufactured. By forming and inserting the pipe into the foam tube, a foam layer uniformly and highly foamed can be obtained.
[0023]
The foaming agent for foaming the thermoplastic resin is not particularly limited as long as it does not degrade the thermoplastic resin. Alternatively, a physical foaming agent which is a volatile liquid can be used.
[0024]
According to a fifth aspect of the present invention, in the method for producing a coated pipe according to the fourth aspect, the foamed tube producing step includes a step of reducing the pressure of the molten resin mixed with the physical foaming agent from the extruder for foaming tube molding. It is sent to a foaming mold and released from the foaming mold to atmospheric pressure to produce a foamed tube.
[0025]
Examples of the physical foaming agent include nitrogen, carbon dioxide, and air as gases, and low-boiling organic hydrocarbons such as propane, butane, and pentane as low-boiling aliphatic hydrocarbons, alcohols, ketones, and esters as volatile liquids. Examples include compounds, halogenated hydrocarbons such as monochlorodifluoromethane, dichlorodifluoromethane, and dichlorotetrafluoroethane. These may be used alone or in combination of two or more.
According to the invention as set forth in claim 5, after the physical foaming agent having a higher foaming pressure than the chemical foaming agent is melted in the resin, the resin is released into the atmosphere to form the foamed tube, so that a predetermined foaming ratio can be obtained. Foaming can be carried out uniformly.
[0026]
According to a sixth aspect of the present invention, in the method for producing a coated pipe according to the fifth aspect, the physical foaming agent is carbon dioxide.
When using an easily volatile liquid as a physical foaming agent, there is a possibility of destruction of the ozone layer or explosion-proof specifications are required as equipment because it is flammable, but carbon dioxide is used as a physical foaming agent Thus, there is no possibility of destruction of the ozone layer, the load on the environment can be reduced, and since it is nonflammable, the equipment does not require explosion-proof specifications and the equipment is simplified. Furthermore, since it has high solubility in resin, a foam layer uniformly and highly foamed can be obtained.
[0027]
According to a seventh aspect of the present invention, in the method for producing a coated pipe according to any one of the fourth to sixth aspects, the expansion ratio of the foam tube formed by extrusion foaming in the foam tube manufacturing step is 5 times or more. It is characterized by the following.
[0028]
The expansion ratio is defined by the following equation (1).
(Expansion ratio) = (specific gravity of resin composition before foaming) / (specific gravity of foam) (1)
Further, the preferable expansion ratio of the foam layer is set to 5 times or more because the slope of the thermal conductivity decrease is large up to 5 times, and in the region of 5 times or more, the dew-proofing and heat insulating performance are remarkably improved. .
In the resin composition forming the foam layer or the skin layer, a stabilizer, an antioxidant, a processing aid, a lubricant, a foaming aid, a filler, a pigment, a flame retardant, and the like are added as necessary. be able to.
[0029]
According to an eighth aspect of the present invention, in the method for manufacturing a coated pipe according to any one of the third to seventh aspects, the slit forming step includes rotating the rotatable circular cutter in the same direction as the traveling direction of the foam tube. It is characterized by being performed by rotational driving.
According to the invention described in claim 8, in the slit forming step, the cutter has a rotatable circular shape and is rotationally driven in the same direction as the traveling direction of the foam tube, so that the foam tube is not sufficiently solidified. Even in the state, there is no occurrence of a slit defect in which the thickness of the foam tube is reduced due to resistance from the cutter, and a good slit can be continuously formed in the foam tube.
Further, it is preferable to control the peripheral speed of the circular cutter to be equal to or higher than the linear speed of the foam tube. This is because a part of the circular cutter is easily affected by the resistance of the foam tube.
[0030]
According to a ninth aspect of the present invention, in the method for manufacturing a coated pipe according to any one of the third to eighth aspects, in the pipe inserting step, the upstream side in the feeding direction of the foamed tube has a tapered shape having a tapered shape. Introducing a foamed tube with a cut into the diameter core, expanding the diameter while transporting the foamed tube, and inserting a pipe from the cutout expanded into the foamed tube being transported. .
According to the ninth aspect of the present invention, the cut of the foam tube can be easily widened by the expanded core, and the pipe can be easily inserted into the foam tube.
[0031]
According to a tenth aspect of the present invention, in the method for manufacturing a coated pipe according to any one of the third to ninth aspects, the pipe inserting step includes a cooling step of cooling the expanded foam tube. It is characterized by the following.
[0032]
When a pipe is inserted into the foam tube while continuously feeding the foam tube, the temperature of the inner and outer surfaces of the foam tube increases when the amount of the foam tube fed out increases, and the foam tube may be stretched. . When the foamed tube expands, the foamed tube shrinks after the skin layer is formed, and the pipe end is cut at the cut portion even when the pipe end of the pipe is largely exposed after manufacturing the coated pipe or when the coated pipe is cut in the middle. Exposure may be large.
[0033]
According to the invention as set forth in claim 10, even if the amount of the foamed tube to be sent out is large, the foamed tube can be cooled in the cooling step in the pipe insertion step, so that the temperature rise can be suppressed and the foamed tube can be prevented from being elongated, Exposure of the pipe from the pipe end of the coated pipe can be prevented.
[0034]
According to an eleventh aspect of the present invention, in the method for manufacturing a coated pipe according to any one of the third to tenth aspects, the step of reducing the diameter of the foamed tube includes a step in which the downstream side in the feed direction of the foamed tube is tapered. The foamed tube in which the pipe is inserted is fed into the body, and the cut portion of the foamed tube is joined to reduce the diameter of the foamed tube.
According to the eleventh aspect, it is possible to easily reduce the diameter of the foamed tube expanded by the cylindrical body.
[0035]
According to a twelfth aspect of the present invention, in the method for manufacturing a coated pipe according to any one of the third to tenth aspects, the step of reducing the diameter of the foamed tube includes a tapered outer peripheral surface having a concave central portion in the axial direction. Using a pair of rotatable rollers, the expanded foam tube is introduced between the two rollers, and the roller pair is pressed in a direction in which the opposing surfaces of the cuts of the foam tube are brought together to reduce the diameter of the foam tube. It is characterized by doing.
[0036]
According to the twelfth aspect of the present invention, the diameter of the expanded foam tube can be easily reduced by using a pair of rotatable rollers having a tapered outer peripheral surface with a concave axial center. it can. Furthermore, since the diameter of the foam tube can be reduced without applying tension to the foam tube, the foam tube can be prevented from shrinking when the coated pipe is cut, and the product dimensions can be stabilized. Can be achieved.
[0037]
According to a thirteenth aspect of the present invention, in the method for producing a coated pipe according to any one of the third to twelfth aspects, the foamed material whose diameter has been reduced after the foaming tube diameter reducing step and before the skin layer forming step. The method includes a step of fusing the opposing surfaces of the cuts of the tube to each other.
As a method of fusing the opposing surfaces of the cut of the foam tube, there is a method of fusing the cut portion continuously in the length direction, and a method of fusing the cut portion intermittently along the cut.
[0038]
According to the thirteenth aspect, since the cut is fused before the skin layer is formed, it is possible to reliably prevent the cut portion from being opened at the time of forming the skin layer, thereby preventing the quality from being deteriorated.
[0039]
According to a fourteenth aspect of the present invention, in the method for manufacturing a coated pipe according to the thirteenth aspect, the break fusing step is performed by fusing with hot air to fuse opposing surfaces of the break. .
According to the fourteenth aspect of the present invention, the surface layer of the cut portion of the foam tube can be directly contacted with a heat source by a simple method, and the cut portion can be fused without breaking the shape of the foam tube.
[0040]
According to a fifteenth aspect of the present invention, in the method for producing a coated pipe according to any one of the third to fourteenth aspects, the skin layer forming step includes forming the skin layer into which the pipe is inserted and reduced in diameter. The skin layer forming resin extruded from the skin layer forming extruder into the skin layer forming mold to form a skin layer on the outer periphery of the foamed tube. .
[0041]
The thickness of the skin layer is preferably 100 μm or more, more preferably 200 μm or more, because if the thickness is too small, the surface of the foam layer cannot be completely protected by friction or scratching.
In addition, since there is a high possibility that irregularities on the foam surface are transferred to the skin layer, a concealable pigment is added to the resin to improve the appearance, or embossing, embossing, or the like is performed. Is preferred.
According to the fifteenth aspect, the skin layer can be easily formed on the outer circumference of the foamed tube whose diameter has been reduced by inserting the pipe.
[0042]
The invention according to claim 16 is an apparatus for manufacturing a coated pipe in which a foam layer is formed on a pipe surface and further a skin layer is formed on the outer periphery of the foam layer, wherein the foam tube serving as the foam layer is A slit forming process section that continuously cuts the foam tube in the longitudinal direction of the tube while continuously supplying the pipe, and a pipe insertion process that inserts a pipe into the foam tube from the cut while expanding the diameter of the cut foam tube. Part, a foam tube reducing step for reducing the diameter of the foam tube in which the pipe is inserted, and a skin layer forming step for forming a skin layer on the outer periphery of the foam tube in which the pipe is inserted and reduced in diameter. It is characterized by having.
[0043]
According to the apparatus for manufacturing a coated pipe according to claim 16, a cut is formed in the manufactured foamed tube that becomes the foamed layer, instead of directly forming the foamed layer covering the surface of the pipe on the outer surface of the pipe. Then, by inserting the pipe into the foam tube, the pipe is covered with the foam tube, and a coated pipe having a skin layer formed on the outer periphery of the foam tube can be manufactured. Is obtained.
[0044]
According to the apparatus for manufacturing a coated pipe according to claim 17, in the apparatus for manufacturing a coated pipe according to claim 16, the slit forming process unit includes a rotatable circular cutter and a cooling device for the circular cutter. It is characterized by having.
[0045]
According to the seventeenth aspect of the present invention, by using the rotatable circular cutter, it is possible to rotate and drive in the same direction as the traveling direction of the foam tube, and it is possible to suppress the resistance to the foam tube. In addition, since the circular cutter is cooled, the foam tube has residual heat due to extrusion molding, and frictional heat is generated on the cutter blade, so it is possible to suppress the rise in the temperature of the cut portion when forming the cut, and to increase the temperature of the cut portion. This makes it possible to prevent the formation of breaks due to the above.
[0046]
According to an eighteenth aspect of the present invention, in the apparatus for manufacturing a coated pipe according to the sixteenth or seventeenth aspect, the pipe insertion step has a taper in which the upstream side in the feed direction of the foam tube has a tapered shape. The expanded core is provided with a concave portion that is not in contact with the foam tube on the outer surface, and the pipe is inserted into the foam tube from a cut of the expanded foam tube by the diameter expansion. For providing a guide passage for the vehicle.
[0047]
The concave portion provided in the enlarged core has a plurality of annular concave grooves extending in the circumferential direction on the surface of the enlarged core, a spiral groove formed on the surface of the enlarged core, a concave portion extending in the feeding direction of the foam tube. It is obtained by forming a plurality of grooves.
[0048]
According to the invention as set forth in claim 18, the expanded tube is expanded while the inner surface of the expanded tube is along the tapered outer peripheral surface of the expanded core, and the pipe is inserted into the expanded tube from the guide passage of the expanded core. It can be easily inserted. In addition, the concave portion provided in the expanded core reduces the contact area between the expanded core and the inner surface of the expanded tube when the inner surface of the expanded tube is brought into contact with the outer peripheral surface of the expanded core, thereby reducing friction. While the diameter expansion by the diameter expansion core can be performed smoothly, the temperature rise of the foam tube due to friction can be reduced.
[0049]
According to a nineteenth aspect of the present invention, in the apparatus for manufacturing a coated pipe according to any one of the sixteenth to eighteenth aspects, the pipe insertion step includes a cooling mechanism for cooling the expanded foam tube. It is assumed that.
According to the invention as set forth in claim 19, even if the amount of the foamed tube sent out is large, the foamed tube can be cooled by the cooling mechanism in the pipe insertion step, so that the temperature rise of the foamed tube is suppressed and the expansion of the foamed tube is expanded. Can be prevented, and exposure of the pipe from the pipe end of the coated pipe after manufacture can be prevented.
[0050]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 schematically shows a first embodiment of a manufacturing apparatus for manufacturing a coated pipe according to the method for manufacturing a coated pipe of the present invention. The coated pipe manufacturing apparatus shown in FIG. The pipe 1 can be manufactured. As shown in FIG. 5, the coated pipe 1 has a foam layer 12 which is a sound insulation layer or a heat insulating layer formed on the surface of a pipe 11, and further has a skin layer 13 formed on the surface of the foam layer 12.
[0051]
The coated pipe manufacturing apparatus according to the first embodiment includes a slit forming step (slit) for continuously forming cuts 21 in the foam tube 2 serving as the foam layer 12 shown in FIG. 2 in the tube longitudinal direction as shown in FIG. Forming step), a pipe insertion step (pipe insertion step) in which the pipe 11 is inserted into the foam tube 2 from the cut 21 while expanding the diameter of the foam tube 2 having the cut 21 therein, and foaming in which the pipe 11 is inserted. A foam tube reducing step (foam tube reducing step) for reducing the diameter of the tube 2 to the state shown in FIG. 4 and forming a skin layer 13 on the outer periphery of the reduced foam tube 2 with the pipe 11 inserted therein. Then, the coated pipe 1 is manufactured through each manufacturing process of the skin layer forming process section (skin layer forming process) to be in the state shown in FIG. The slit forming process section also has a foam tube manufacturing process for continuously supplying the foam tube 2.
[0052]
As shown in FIG. 1, in the coated pipe manufacturing apparatus according to the first embodiment, the foamed tube manufacturing process includes a foamed tube manufacturing process unit 31 a that extrudes and forms the foamed tube 2 alone.
In addition, between the pipe insertion step and the foam tube reducing step, a heating unit 81 shown by a virtual line in FIG. 1 is provided to intermittently connect the opposing surfaces of the cuts 21 of the foam tube 2 into which the pipe is inserted. Alternatively, a break fusing step of continuously fusing may be provided.
[0053]
In this case, it is preferable that the heating unit is configured by a hot air nozzle 81 that blows hot air onto the foam tube 2. The specific configuration and operation and effect are the same as those of the heating unit described in a second embodiment described later, and thus will be described in the second embodiment.
[0054]
The coated pipe manufacturing apparatus according to the first embodiment will be specifically described. As shown in FIG. 1, the coated pipe manufacturing apparatus according to the first embodiment includes a foamed tube manufacturing process section 31 a for extruding the foamed tube 2 to be the foamed layer 12 by itself and a flexible pipe 11. It has a pipe feeding process section 32a to take out, a foam layer forming step section 33 for performing a slit forming step, a pipe inserting step, and a foam tube reducing step, and a skin layer forming step section 34 for performing a skin layer forming step. I have.
[0055]
The foamed tube manufacturing process section 31a includes a foamed tube forming extruder 41 in which a foamable thermoplastic resin composition for forming the foamed layer 12 is melt-kneaded, and a melt extruded from the foamed tube forming extruder 41. A foaming mold 42 for molding the foamed tube 2 into which resin is injected, and a first take-off machine 43 for receiving the foamed tube 2 coming out of the foaming mold 42 are provided.
[0056]
The extruder 41 for forming a foam tube includes a raw material hopper 41a to which a thermoplastic resin composition is supplied and a foaming agent supply unit 41b, and a resin composition for forming the foam layer 12 from the raw material hopper 41a. On the other hand, the physical foaming agent in the cylinder 44 is supplied from the foaming agent supply section 41b into the extruder 41 for forming a foamed tube.
[0057]
In the supply path between the cylinder 44 and the foaming agent supply section 41b, a cooling device 45 and a metering pump 46 are provided. In this embodiment, since the carbon dioxide gas is used as the physical foaming agent, the supply efficiency is reduced. A cooling device 45 is provided in front of the metering pump 46 in order to increase the pressure, and the cooling device 45 liquefies the carbon dioxide gas and supplies it to the metering pump 46.
[0058]
Further, the metering pump 46 controls the supply amount of the foaming agent into the foaming tube forming extruder 41 so that a desired expansion ratio can be obtained with respect to the resin extrusion amount of the foaming tube forming extruder 41. ing.
[0059]
The expansion ratio can be controlled by the amount of blowing agent dissolved in the molten resin. When carbon dioxide is used as a physical blowing agent, 1 wt% or more of carbon dioxide gas is dissolved in the molten resin to obtain an expansion ratio of 5 times or more. Need to be done.
[0060]
However, if the carbon dioxide gas is supplied excessively with respect to the target magnification, bubbles are generated at the outlet of the foaming mold 42 and gas escape is promoted, and as a result, the magnification does not increase. It is necessary to control the blowing agent supply amount.
[0061]
The foaming tube forming extruder 41 dissolves the foaming agent into the molten resin from the foaming agent supply unit 41b while heating and melting the resin composition supplied from the raw material hopper 41a. The molten resin is extruded into a foaming mold 42 connected to 41.
[0062]
In addition, in the foaming tube forming extruder 41, a screw groove provided in the foaming tube forming extruder 41 so that the blowing agent can be stably supplied from the foaming agent supply unit 41b into the foaming tube forming extruder 41. The depth is formed so as to be deeper at a portion facing the position where the foaming agent supply section 41b is formed, so that the pressure of the molten resin is temporarily reduced when the foaming agent is supplied. In order to efficiently dissolve the foaming agent in the molten resin, it is preferable to provide the screw with a mixing element such as dalmage.
[0063]
Although not shown, the foaming mold 42 is formed of an inner core and an outer mold for molding into a tube shape. The inner core is held by a bridge, and the outer mold is formed by a band heater or a medium such as oil. The temperature can be adjusted.
[0064]
The first take-up device 43 is constituted by a pair of first transport belts 43a that are driven to rotate. The first transport belt 43a sandwiches the foam tube 2 and the first transport belt 43a drives the foam tube 2 to rotate. Is sent to the foam layer forming section 33.
[0065]
Therefore, in the foaming mold 42, the resin composition supplied in a state where the pressure is reduced from the foaming tube molding extruder 41 is temperature-adjusted to the foaming optimum temperature, and the resin composition in a tube state is formed from the foaming mold 42. When the resin composition is released to the atmospheric pressure, the resin composition foams, and a uniform highly foamed foam tube 2 as shown in FIG. 2 is manufactured.
[0066]
The optimum foaming temperature depends on the plasticizing effect of the resin depending on the amount of the foaming agent dissolved in the molten resin. Therefore, when the resin is crystalline, the melting point is ± 10 ° C., and when the resin is amorphous, the glass transition is performed. It is preferable to set the temperature within a range of ± 10 ° C. Further, it is preferable to provide the foam mold 42 with an uneven thickness adjustment mechanism.
[0067]
As shown in FIG. 1, the pipe feeding section 32a for feeding the pipe 11 includes a feeding machine 51 to which a pipe 11 manufactured and wound in advance by another extruder is attached, and a pipe 11 from the feeding machine 51. A second take-up machine 52 for feeding the foamed material to the foam layer forming section 33; and a curl correcting device 53 provided between the pay-out machine 51 and the second take-up machine 52.
The pipe 11 used in the present embodiment is formed of a flexible synthetic resin pipe and is long.
[0068]
The feeder 51 is composed of a rotating drum fixed to bearings, and the second take-up device 52 is composed of a pair of second transport belts 52a that are driven to rotate, and holds the pipe 11 between the second transport belts 52a. The pipe 11 is sent to the foam layer forming section 33 by the rotation of the second conveyor belt 52a.
[0069]
The curl correction device 53 corrects a curl attached to the pipe 11, and as shown in FIG. 1, includes three correction rollers 53a which are alternately arranged. The curl of the pipe 11 is corrected by the rollers 53a. The correction roller 53a has a shape in which the longitudinal center of the roller surface is tapered and concave.
[0070]
If the pipe is not flexible, a straight pipe cut to a predetermined length may be continuously sent out to the foam layer forming step unit 33 using a take-off machine, or will be described later. As in the fourth embodiment shown in FIG. 16, the pipe 11 manufactured in the extrusion line of the pipe manufacturing process unit 32 b having the pipe forming extruder 54 is continuously transferred to the foam layer forming process unit 33 by the take-off machine 52. You may send it out.
[0071]
Further, in the first embodiment, the process of feeding the pipe 11 is performed in parallel with the above-described foam tube manufacturing process, the slit forming process described later, and the process of expanding the diameter of the foam tube.
[0072]
Further, the foam layer forming step section 33 includes a cut forming apparatus 61 that cuts the cut 21 continuously in the tube longitudinal direction in the foam tube 2 in the slit forming step (slit forming step section). In the process section), there is provided a pipe insertion device 62 that expands the diameter of the foamed tube 2 while transporting the same, and inserts the pipe 11 from the cut 21 expanded by the expanded core 62a into the transported foamed tube 2. In the diameter reduction step (foam tube reduction step), a foam tube reduction device 63 for reducing the diameter of the foam tube 2 into which the pipe 11 is inserted is provided.
[0073]
As shown in FIG. 1, the cut forming device 61 is fixed to a support plate 64, and is a linear, long and long cut that continuously cuts the foam tube 2 in the extrusion direction (the longitudinal direction of the tube). A cutter blade 61a, a first holding roller 61b provided so as to face the tip of the long cutter blade 61a, and a support to which the long cutter blade 61a and the first holding roller 61b are attached and fixed to a support plate 64 61c.
[0074]
As shown in FIG. 6, the long cutter blade 61a is attached to the support body 61c so as to be able to advance and retreat in the radial direction with respect to the foam tube 2, and the long cutter blade 61a is attached to the U-shaped holder 61d. The holder 61d is fixed via a swing fixing plate 61e, and is supported by the support 61c so that the holder 61d can advance and retreat by operating the position adjustment handle 61f with respect to the support 61c. The cutting depth can be adjusted according to the thickness of the foam tube 2 by supporting the long cutter blade 61a so as to be able to advance and retreat to the support body 61c.
[0075]
Further, the long cutter blade 61a is fixed to a swing fixing plate 61e so that the cutting angle to the foam tube 2 can be changed, and the swing fixed plate 61e is swung to a holder 61d by a support shaft (not shown). While being movably supported, the angle adjustment dial 61g is attached to the support shaft, and by rotating the angle adjustment dial 61g, the swing fixing plate 61e is swung to adjust the angle of the long cutter blade 61a. ing.
[0076]
The adjustment angle can be adjusted from a cut angle of 30 degrees to 45 degrees with respect to the surface of the foam tube 2. The reason why the cut angle can be adjusted is that an appropriate cut angle changes depending on the surface temperature of the foam tube 2.
[0077]
In forming the cut 21, the cut forming device 61 includes a cooling mechanism that cools the foam tube 2 and the long cutter blade 61a when the cut 21 is formed. A cooling step of cooling the length cutter blade 61a is provided. The cooling may be performed on either the foam tube 2 or the long cutter blade 61a, or may be performed simultaneously.
[0078]
As means for cooling the foam tube 2 and the long cutter blade 61a, a cooling nozzle 61h is also attached to a support body 61c on which the long cutter blade 61a is supported, and the discharge port of the cooling nozzle 61h is placed on the surface of the foam tube 2 The cooling air discharged from the cooling nozzle 61h is blown to the location where the cut 21 of the foam tube 2 is formed to cool the foam tube 2 and the long cutter blade 61a.
[0079]
The cooling nozzle 61h is provided so as to be aligned with the long cutter blade 61a so as to penetrate the position adjustment handle 61f attached to the support 61c, the support 61c, and the holder 61d, and bend the discharge-side tip. ing. Then, according to the angle adjustment of the long cutter blade 61a, cooling air is directly blown from the discharge port of the cooling nozzle 61h to the tip of the long cutter blade 61a, or slightly upstream from the tip of the long cutter blade 61a. Or spraying cooling air.
[0080]
In the first embodiment, since the foam tube 2 and / or the long cutter blade 61a are forcibly cooled, the extrusion amount of the foam tube 2 in the manufacturing process of the foam tube 2 increases, and the inner and outer surface temperatures of the foam tube 2 increase. When the cut 21 is formed, the cut position of the foam tube 2 and / or the long cutter blade 61a is increased even if the frictional heat of the long cutter blade 61a increases due to the increase in the feed amount of the foam tube 2 and the feeding amount of the foam tube 2. Can be cooled, so that occurrence of molding failure of the cut 21 can be prevented.
[0081]
Although not shown, the first holding roller 61b has a shape in which the longitudinal center of the roller surface is tapered and recessed, and is rotatably supported by the support 61c. The foamed tube 2 is held at a predetermined position by always positioning the conveyed foamed tube 2 in the concave portion of the first holding roller 61b. Since the foam tube 2 is held by the first holding roller 61b, the cut 21 can be linearly cut at a predetermined position of the foam tube 2 by the long cutter blade 61a.
[0082]
A plurality of guide rollers 47 are provided between the first take-up device 43 and the cut forming device 61 to guide the foam tube 2 sent from the first take-up device 43 to the cut forming device 61.
[0083]
The cut 21 is not limited to the linear long cutter blade described above, but may be, for example, a disk-shaped cutter blade fixed to a bearing applied to a side surface of the foam tube to cut the disk-shaped cutter blade. A cut may be made by rotation.
[0084]
An embodiment of a cut forming device 61 using a disk-shaped cutter blade will be described with reference to FIG. In the cut forming device 61 using the disk-shaped cutter blade 61i shown in FIG. 7, the same members as those of the cut forming device 61 shown in FIG.
[0085]
The cut forming device 61 using the disc-shaped cutter blade 61i is the same as the cut forming device 61 shown in FIG. 1 except that the long cutter blade 61a is replaced with the disc-shaped cutter blade 61i in the manufacturing apparatus shown in FIG. A disk-shaped cutter blade 61i fixed to the support plate 64 and continuously cuts 21 in the foaming tube 2 in the extrusion direction (longitudinal direction of the tube), and faces the circumferential tip of the disk-shaped cutter blade 61i. A first holding roller 61b provided in such a manner as described above, and a support 61c to which the disk-shaped cutter blade 61i and the first holding roller 61b are attached and fixed to the support plate 64 are provided.
[0086]
As shown in FIG. 7, the disk-shaped cutter blade 61i is attached to a support 61c so as to be able to advance and retreat in the radial direction with respect to the foam tube 2, and the disk-shaped cutter blade 61i is provided with a U-shaped holder. The holder 61d is fixed to the support 61d via a rotation shaft 61j, and the holder 61d is supported by the support 61c so that the holder 61d can advance and retreat by operating the position adjustment handle 61f with respect to the support 61c.
[0087]
Although not shown, a rotating shaft 61j for rotating the disc-shaped cutter blade 61i is connected at one end to a motor, and the motor is driven to rotate the rotating shaft 61j to rotate the disc-shaped cutter blade 61i. 61i is rotated. Further, the disc-shaped cutter blade 61i is rotated in the same direction as the direction in which the foam tube 2 is sent out.
The cutting depth can be adjusted according to the thickness of the foam tube 2 by supporting the disc-shaped cutter blade 61i on the support 61c so as to be able to advance and retreat.
[0088]
Further, the cut forming apparatus 61 shown in FIG. 7 is provided with a cooling mechanism for cooling the disc-shaped cutter blade 61i when forming the cut 21 in forming the cut 21, and in the slit forming step, the disc-shaped cutter blade 61i is provided. And a cooling step of cooling.
[0089]
As means for cooling the disk-shaped cutter blade 61i, a cooling nozzle 61h is also attached to a support 61c on which the disk-shaped cutter blade 61i is supported, and the cooling air discharged from the cooling nozzle 61h is used to cool the foam tube 2. The disk-shaped cutter blade 61i is cooled by spraying it near the portion where the cut 21 is to be formed.
[0090]
The cooling nozzle 61h is provided so as to penetrate the position adjustment handle 61f attached to the support 61c, the support 61c and the holder 61d, and to traverse the disk-shaped cutter blade 61i. Cooling air is directly blown from the discharge port to the tip of the disc-shaped cutter blade 61i.
[0091]
Since the disc-shaped cutter blade 61i is also forcibly cooled by the notch forming device 61 shown in FIG. 7, the extrusion amount of the foam tube 2 in the manufacturing process of the foam tube 2 increases, and the inner and outer surface temperatures of the foam tube 2 increase. Is increased, or even if the feed amount of the foam tube 2 is large and the frictional heat of the disc-shaped cutter blade 61i is increased, the disc-shaped cutter blade 61i can be cooled when forming the cut 21. It is possible to prevent molding defects from occurring.
[0092]
The pipe insertion device 62 according to the first embodiment shown in FIG. 1 includes an enlarged core 62 a for expanding the diameter of the foam tube 2 while transporting the foam tube 2, and a second holding roller 62 b for holding the foam tube 2.
[0093]
As shown in FIG. 1, FIG. 6, and FIG. 7, the enlarged core 62a has a tubular shape in which the upstream side in the tube transport direction is tapered and the downstream end is open, and the downstream side in the tube transport direction is bent. An insertion hole 62d for inserting the pipe 11 into the large-diameter core 62a is formed on the outer bent surface of the bent portion 62c. The insertion hole 62d serves as a guide passage for inserting the pipe 11 into the inside of the foam tube 2.
[0094]
In the pipe insertion device 62, the diameter of the foam tube 2 is increased along a tapered surface formed on the upstream side in the transport direction of the diameter-increased core 62a. The core is introduced into the enlarged core 62a so as to be positioned on the surface.
[0095]
Therefore, when the foam tube 2 is bent at the bent portion 62c of the expanded core 62a, the cut 21 further widens, and the diameter of the foam tube 2 further increases. By using the bent expanded core 62a, the cut 21 of the foam tube 2 can be easily expanded by the bent portion 62c of the expanded core 62a so that the pipe 11 can be easily inserted.
[0096]
The second holding roller 62b has a shape in which the center of the roller surface in the longitudinal direction of the roller is tapered, and is rotatably supported by the support plate 64. The foamed tube 2 is always positioned in the recess of the second holding roller 62b, so that the foamed tube 2 is foamed by the second holding roller 62b and the enlarged core 62a so as not to deviate from the enlarged core 62a. The tube 2 is held.
[0097]
In the present embodiment, the bent portion 62c is formed in the expanded core 62a, and the foamed tube 2 is bent so that the cut 21 of the foamed tube 2 is located on the outer bent surface, so that the foamed tube 2 is fed from the feeder 51. While the pipe 11 is being conveyed linearly, the conveying path of the foamed tube 2 is joined to the conveying path of the pipe 11 at the bent portion forming position, and from the cut 21 expanded at the bent portion 62c, the expanded core 62a is formed. The pipe 11 is inserted into the insertion hole 62d, and the foam tube 2 can be easily fitted into the pipe 11.
[0098]
At this time, in order to reduce friction between the outer surface of the expanded core 62a and the inner surface of the foam tube 2, it is preferable to perform a processing such as fluororesin coating on the outer surface of the expanded core 62a to reduce frictional resistance.
[0099]
Further, as shown in FIGS. 6 and 7, a plurality of cooling air discharge holes 62e are formed on the outer peripheral surface of the expanded core 62a on the insertion side (upstream of the bent portion 62c) of the foam tube 2 and expanded. A cooling air supply pipe 62f for supplying cooling air to the inside of the diameter core 62a is connected to the enlarged diameter core 62a. The cooling air supplied from the cooling air supply pipe 62f to the inside of the expanded core 62a is discharged from the cooling air discharge hole 62e, and cools the foam tube 2 inserted into the expanded core 62a from the inner surface side. I have.
[0100]
In order to reduce the frictional resistance between the outer surface of the expanded core 62a and the inner surface of the foam tube 2, the expanded core 62a shown in FIGS. 8 to 11, a plurality of annular grooves (recesses) 62g extending in the circumferential direction are formed on the outer surface of the enlarged diameter core 62a, as shown in FIGS. A plurality of vertical grooves extending in the length direction of the spiral groove and the enlarged core 62a are formed, and a concave portion for reducing the contact area of the foam tube 2 with the enlarged core 62a is formed to reduce frictional resistance. You may do so.
[0101]
A case where a plurality of annular grooves 62g extending in the circumferential direction are formed on the outer surface of the enlarged core 62a will be described with reference to FIGS. FIG. 9 is a cross-sectional view of the enlarged core 62a shown in FIG.
The expanded diameter core 62a shown in FIG. 8 is formed by bending the foam tube 2 and inserting the pipe 11 into the foam tube 2 while keeping the pipe 11 in a straight state, and has a taper that tapers toward the upstream side in the tube transport direction. 62h is formed, and the downstream side in the tube transport direction is bent.
[0102]
A plurality of annular grooves (recesses) 62g extending in the circumferential direction are formed on the outer peripheral surface of the enlarged core 62a upstream of the bent portion 62c in the tube transport direction and downstream of the taper 62h.
Further, an insertion hole 62d for inserting the pipe 11 into the enlarged core 62a is formed on the outer bent surface of the bent portion 62c. The insertion hole 62d serves as a guide passage for inserting the pipe 11 into the inside of the foam tube 2, and has a downstream end opened.
[0103]
As shown in FIGS. 8 and 9, a plurality of cooling air discharge holes 62e are formed in an annular groove 62g of the enlarged core 62a, and a cooling air supply for supplying cooling air to the inside of the enlarged core 62a. A passage 62i is formed. The cooling air supplied from the cooling air supply passage 62i to the inside of the expanded core 62a is discharged from the cooling air discharge hole 62e to cool the foam tube 2 inserted into the expanded core 62a from the inner surface side. I have.
[0104]
Further, in the expanded core 62a shown in FIG. 8, the pipe 11 is inserted into the foam tube 2 while keeping the pipe 11 straight while bending the foam tube 2, but as in the expanded core 62a shown in FIG. Alternatively, the diameter of the enlarged core 62a may be linear.
The enlarged core 62a shown in FIG. 10 forms a tapered tapered portion 62h on the upstream side in the tube transport direction, and has an annular groove (recess) extending in the circumferential direction on the outer peripheral surface of the enlarged diameter core 62a downstream of the taper 62h. ) 62g are formed, and an insertion hole 62d for inserting the pipe 11 into the enlarged core 62a is opened at a longitudinally intermediate portion of the enlarged core 62a, and the insertion hole 62d is formed in the enlarged core 62a. It is open at the downstream end.
[0105]
The insertion hole 62d of the enlarged core 62a shown in FIG. 10 has a guide passage curved so that the pipe 11 is bent inside the insertion hole 62d, and the pipe 11 is inserted when the pipe 11 is inserted into the insertion hole 62d. The opening area on the pipe 11 insertion side is formed large so as not to contact the opening end of the hole 62d.
According to the expanded core 62a shown in FIG. 10, the pipe 11 can be curved and inserted into the foam tube 2 while the foam tube 2 is transported linearly.
[0106]
Further, as shown in FIG. 11, the expanded core 62a is bent, but the bending angle is made gentler than that of the expanded core 62a shown in FIG. The pipe 11 may be inserted into the tube 2.
[0107]
The enlarged core 62a shown in FIG. 11 also has a tapered 62h that is tapered on the upstream side in the tube transport direction, and has an annular groove (recess) extending in the circumferential direction on the outer peripheral surface of the enlarged core 62a downstream of the taper 62h. ) 62g are formed, and an insertion hole 62d for inserting the pipe 11 into the enlarged core 62a is opened at a longitudinally intermediate portion of the enlarged core 62a, and the insertion hole 62d is formed in the enlarged core 62a. It is open at the downstream end.
[0108]
Further, the insertion hole 62d of the enlarged core 62a shown in FIG. 11 also has a curved guide passage so that the pipe 11 is bent inside the insertion hole 62d, and the pipe 11 is inserted into the insertion hole 62d when the pipe 11 is inserted into the insertion hole 62d. The opening area on the side where the pipe 11 is inserted is formed wide so that does not contact the opening end of the insertion hole 62d.
[0109]
Next, the foam tube reducing device 63 in the foam tube reducing step in the first embodiment shown in FIG. 1 will be described. The foam tube reducing device 63 for reducing the diameter of the foam tube 2 into which the pipe 11 is inserted is constituted by a conical tapered tubular body 63a whose downstream side in the feed direction of the foam tube 2 is tapered. The foam tube 2 is fed into the tubular body 63a together with the pipe 11, and the foam tube 2 is passed through the tubular body 63a. The diameter of the tube 2 can be reduced.
[0110]
At this time, in order to reduce the friction between the outer surface of the foam tube 2 and the inner surface of the cylindrical body 63a, it is preferable to perform a processing such as fluororesin coating on the inner surface of the cylindrical body 63a to reduce frictional resistance.
[0111]
Further, the skin layer forming process section 34 includes a skin layer forming extruder 71 in which a non-foamable thermoplastic resin composition for forming the skin layer 13 is melt-kneaded, the foam tube 2 is introduced, and the skin layer is formed. The molten resin extruded from the layer forming extruder 71 is supplied to form the skin layer 13 on the outer periphery of the foam tube 2, and a coating pipe coming out of the skin layer forming mold 72. 1 and a third take-off machine 73 for receiving the same.
[0112]
The skin layer forming extruder 71 includes a raw material hopper 71a to which a thermoplastic resin composition is supplied, and the skin layer forming extruder 71 is connected to a skin layer forming die 72.
[0113]
Although not shown, the skin layer forming mold 72 is a crosshead die in which a passage for passing the foam tube 2 and a resin supply path for supplying a molten resin from the skin layer forming extruder 71 are formed. It is. In addition, it is preferable to provide an uneven thickness adjustment mechanism at the outlet. Furthermore, in order to make it difficult for the heat of the molten resin flowing through the resin supply passage to be transmitted to the foam tube 2, a member such as a resin cylinder having heat insulation is inserted into the inner surface of the passage inside the skin layer forming mold 72. It is preferable to keep it.
[0114]
When the foam tube 2 is introduced together with the pipe 11 into the passage of the skin layer forming mold 72, the molten resin for forming the skin layer is supplied to the outer surface of the foam tube 2 from the resin supply path, and the outer periphery of the foam tube 2 is formed. The surface is covered with a skin layer 13.
[0115]
According to the coated pipe manufacturing apparatus in the first embodiment described above, first, in the foamed tube manufacturing process section 31a, the molten resin composition in which carbon dioxide as a foaming agent is dissolved is extruded from the foamed tube forming extruder 41. After that, it is sent to a foaming mold 42 connected to a foam tube forming extruder 41. While the temperature of the foaming mold 42 is adjusted to the optimum foaming temperature, the foamed resin composition formed into a tube from the foaming mold 42 is released to the atmospheric pressure, and the foamed tube having a uniform foaming state as shown in FIG. 2 are manufactured. The foam tube 2 coming out of the foam mold 42 is sent to the foam layer forming section 33 by the first take-off device 43.
[0116]
In the pipe feeding section 32a, the pipe 11 is fed from the feeding machine 51 by the second take-off machine 52, and sent out to the foam layer forming section 33 while the curl is corrected by the curl correcting device 53.
[0117]
In the foam tube 2 sent to the foam layer forming step 33 by the first take-off device 43, the cut 21 is continuously formed in the extrusion direction (the longitudinal direction of the tube) by the cutter blade 61a of the cut forming device 61. The state shown in FIG. 3 is obtained.
[0118]
The expanded tube 2 is guided by a tapered surface formed on the upstream side of the expanded core 62a in the conveying direction in the pipe insertion device 62, and the expanded tube 2 is press-fitted into the expanded core 62a to expand the diameter. At the bent portion 62c of the radial core 62a, the cut 21 of the foam tube 2 is further widened, and the pipe 11 is inserted from the cut 21 into the insertion hole 62d of the expanded core 62a located inside the foam tube 2.
[0119]
As described above, the foam tube 2 that has undergone the foam tube manufacturing process, the slit forming process, and the foam tube expanding process is merged with the pipe 11 drawn out in the pipe feeding process, and the pipe 11 is inserted into the foam tube 2. First, the pipe 11 is sent out by the second take-off machine 52 and inserted into the enlarged core 62a from the notch.
[0120]
When the pipe 11 passes through the expanded core 62 a and the pipe 11 is inserted into the foam tube 2, the expanded tube 2 is reduced in diameter by the foam tube reducing device 63. At this time, the foam tube 2 is fed together with the pipe 11 into the tapered tubular body 63a, and the foam tube 2 is passed through the tubular body 63a. The portion is easily closed, the diameter of the foam tube 2 is reduced, and the state shown in FIG. 4 is obtained.
[0121]
Next, the foamed tube 2 reduced in diameter with the pipe 11 inserted therein is introduced into a skin layer forming die 72 connected to a skin layer forming extruder 71, and the skin tube forming mold 72 is formed. The molten resin for forming the skin layer is supplied from the skin layer forming extruder 71 while continuously passing the foam tube 2 in which the pipe 11 is inserted into the passage of the mold 72. Thereby, the outer peripheral surface of the foam tube 2 covering the outer periphery of the pipe 11 in the skin layer forming mold 72 is further covered with the skin layer 13, and the covered pipe 1 shown in FIG. 5 is obtained.
[0122]
The coated pipe 1 coming out of the skin layer forming mold 72 is taken up by a third take-up machine 73 and taken up by a take-up machine (not shown).
When the pipe is flexible, the coated pipe is wound by a winder. When the pipe is not flexible, the coated pipe is cut into a predetermined length using a cutter.
[0123]
In the first embodiment, the foam layer 12 covering the surface of the pipe 11 is not directly formed on the outer surface of the pipe 11, but only the foam tube 2 serving as the foam layer 12 is manufactured. Since the pipe 11 is covered with the foam tube 2 by inserting the pipe 11, the foam layer 12 which is uniformly and highly foamed can be obtained. Further, a series of processes for manufacturing the coated pipe 1 can be performed in-line to continuously manufacture the coated pipe, and the cooling rate in the outer diameter-regulated mold is rate-limiting as in the prior art, thereby increasing the production speed. Since the problem of no covering pipe can be solved, the coated pipe 1 can be manufactured efficiently and at low cost.
[0124]
In the first embodiment, the tapered tubular body 63a is used as the foam tube reducing device 63 in the foam tube reducing step. However, the foam tube reducing step of reducing the diameter of the foam tube 2 into which the pipe 11 is inserted is performed in the foam tube reducing step. The foamed tube 2 is not limited to the tapered tubular body 63a of the first embodiment, but is constituted by a pair of pressing bodies that press the cuts 21 of the expanded foamed tube 2 in the butting direction, and sandwich the foamed tube 2 by the pressed body. By doing so, the diameter of the foam tube 2 may be reduced.
[0125]
For example, as another embodiment of the foam tube reducing device 63 for reducing the diameter of the foam tube 2 into which the pipe 11 is inserted, as shown in the second embodiment in FIG. There is an apparatus using a pair of rotatable rollers 63b having an outer peripheral surface.
[0126]
The coated pipe manufacturing apparatus according to the second embodiment for manufacturing the coated pipe shown in FIG. 12 is different from the manufacturing apparatus according to the first embodiment in the specific configuration of the foam tube reducing device 63 in the foam tube reducing step. In addition, a cut fusion step for fusing the cut 21 of the foam tube 2 is provided between the foam tube expanding step and the foam tube reducing step, and other configurations are the same as those of the first embodiment. , The same reference numerals are used for the same components, and the description is omitted.
[0127]
As shown in FIGS. 12 and 13, the foam tube reducing device 63 according to the second embodiment includes a pair of rotatable concave rollers 63 b having a tapered outer peripheral surface with a concave central portion in the axial direction. I have.
[0128]
In the foam tube reducing device 63 according to the second embodiment, the expanded foam tube 2 is introduced between two concave rollers 63b, and is pressed in a direction in which the cuts 21 of the foam tube 2 are brought into contact with each concave roller 63b. Then, the portion of the cut 21 of the foamed tube 2 expanded by the expanded core 62a is closed, and the diameter of the foamed tube 2 is reduced.
[0129]
Further, on the upstream side of the concave roller 63b, as shown in FIG. 12 and FIG. 13, a cut fusion device 8 for fusing the cut 21 of the foam tube 2 is provided. It comprises a supply device (not shown) and a hot air nozzle 81 serving as a heating unit. The cut fusion device 8 melts the surface resin of the cut 21 of the foam tube 2 into which the pipe 11 is inserted by hot air discharged from the hot air nozzle 81, and compresses the resin by the two concave rollers 63 b of the foam tube diameter reducing device 63. When making the diameter, the cut 21 is fused, and the cross section of the fused portion can be in the state shown in FIG.
[0130]
The hot air supply device includes a fan and a heater (not shown), and can control the temperature of the hot air supplied to the hot air nozzle 81. By controlling at or above the melting point, the skin resin of the cut 21 can be melted.
[0131]
The purpose of fusing the cut 21 of the foamed tube 2 is to prevent the cut 21 from being opened in the skin layer forming process section 34, and whether to perform fusing at regular intervals or continuous fusing is intended. Can be selected accordingly. By controlling on / off of the fan of the hot air supply device, the surface resin of the cut 21 can be melted intermittently or continuously.
[0132]
The cut surface fusion step performed by the cut fusion device 8 is not limited to the above-described cut surface fusion method in which hot air is blown, and the cut 21 is brought into direct contact with a hot plate made of a heater and a metal plate to form a surface resin of the cut 21. May be melted.
[0133]
As described above, in the second embodiment, since the foam tube reducing device 63 uses the pair of rotatable rollers 63b having a tapered outer peripheral surface with a concave center in the axial direction, the expanded foam tube 2 has a larger diameter. Can be easily reduced in diameter, and the melted cut 21 can be easily fused. Moreover, since the diameter reduction operation of the foam tube 2 by the concave roller 63b can be performed without applying tension to the foam tube 2, it is possible to prevent only the foam tube 2 from shrinking when the covering pipe is cut. And the product dimensions can be stabilized.
[0134]
Further, in the second embodiment, after the foam tube reducing step and before the skin layer forming step, the structure having a cut fusion step of fusing the opposing surfaces of the cut 21 of the reduced diameter foam tube 2 to each other is provided. Therefore, the cut 21 can be fused before the skin layer 13 is formed, and the cut 21 can be reliably prevented from opening when the skin layer 13 is formed, and the quality can be prevented from deteriorating. .
[0135]
In addition, in the break fusing step, the surface layer resin at the break 21 of the foam tube 2 is melted by hot air blown from the hot air nozzle 81 so that the opposing surfaces of the break 21 are fused to each other. The cut 21 can be fused without causing the foam tube 2 to lose its shape by directly contacting the heat source by the method.
[0136]
Further, in the first embodiment, the foaming tube supplying step is constituted by the foaming tube manufacturing process section 31a, and in the foaming tube diameter reducing step, a tapered cylindrical body 63a is used as the foaming tube diameter reducing device 63. As shown in the third embodiment, the foam tube 2 is prepared in a separate process in advance and wound on a reel 47, the foam tube 2 is drawn out from the reel 47, and the foam layer forming step 33 A foam tube feeding process section 31b is provided to feed the cut tube, and similarly to the above-described second embodiment, the cut fusion process by the hot air nozzle 81 and the foaming by the foam tube reducing device 63 including the two concave rollers 63b. A tube reducing step may be provided.
[0137]
Further, in the first embodiment, in order to fit the foam tube 2 into the pipe 11, a pipe feeding section 32a is provided, and the pipe 11 manufactured in advance is fed from the feeding machine 51 to reach the pipe inserting step. However, as in the fourth embodiment shown in FIG. 16, the thermoplastic resin composition for forming the pipe 11 is melt-kneaded and extruded from the pipe forming extruder 54, and extruded from the pipe forming extruder 54. The molten resin is injected, and a pipe manufacturing process section 32b including a mold 55 for molding the pipe 11 and a second take-off machine 52 for receiving the pipe 11 coming out of the mold 55 is provided, and the above-described process is performed. As in the second embodiment, a cut fusion step using the hot air nozzle 81 and a foam tube reducing step using the foam tube reducing device 63 including two concave rollers 63b are provided. It may be so that.
[0138]
【Example】
Hereinafter, the present invention will be described in detail with reference to examples. However, the examples are illustrative and do not limit the present invention.
(Example 1)
Example 1 used the manufacturing apparatus in the above-described second embodiment (FIG. 12). A mixture of 100 parts by weight of low-density polyethylene (manufactured by Nippon Polychem Co., Ltd .; product number "LF440HB") and 3 parts by weight of talc (manufactured by Sumika Color Co., Ltd .; product number "SS-11-20") is mixed with an extruder 41 for foam tube molding. It was supplied to the raw material hopper 41a, and was heated and melted by the extruder 41 for forming a foamed tube. On the other hand, carbon dioxide gas was supplied as a foaming agent from a cylinder 44 to the foaming agent supply section 41b of the foam tube extruder 41.
[0139]
At this time, after the carbon dioxide gas discharged from the cylinder 44 is cooled by the cooling device 45, the amount of the resin extruded by the foaming tube forming extruder 41 is set to 0.2 kg / h using the metering pump 46. The mixture was supplied in a controlled manner, and kneaded at 120 ° C. in an extruder 41 for forming a foamed tube. The temperature of the foaming mold 42 was set at 108 ° C., and was released from the outlet having an inner diameter of 3 mm and an outer diameter of 6 mm to atmospheric pressure to obtain a uniform foamed tube 2 having an inner diameter of 18 mm, an outer diameter of 24 mm, and an expansion ratio of about 6 times.
[0140]
Next, the foam tube 2 was taken out by the first take-off device 43, sent to the cut forming device 61 via the guide roller 47, and the cut 21 was continuously formed in the foam tube 2 in the extrusion direction by the long cutter blade 61a. . Subsequently, the foam tube 2 was guided to the large-diameter core 62a, the opening was introduced into the large-diameter core 62a, and the cut 21 of the foam tube 2 was widened at the bent portion 62c.
[0141]
On the other hand, a cross-linked polyethylene pipe having an outer diameter of 17 mm as the pipe 11 is drawn out at a speed of 3 m / min from the feeder 51 by the second take-up machine 52 and inserted into the expanded core 62a to cover the foamed tube 2 11 was obtained. Subsequently, the cut portion of the expanded foam tube 2 whose diameter was expanded by a pair of rotatable concave rollers 63b whose central portion in the axial direction was tapered was pressed in the abutting direction, thereby being expanded by the expanded core 62a. The cut 21 was closed, and the pipe 11 was continuously inserted into the flow path of the skin layer forming die 72 connected to the skin layer forming extruder 71. In addition, in Example 1, the fusion of the cut was not performed.
[0142]
On the other hand, a mixture of 100 parts by weight of low-density polyethylene (manufactured by Nippon Polychem; product number "LF440HB") and 5 parts by weight of a pigment masterbatch (manufactured by Toyo Ink Company; product number "TET3MA1070RG") is extruded from the raw material hopper 71a for forming a skin layer. The mixture was supplied to a mixing machine 71 and melt-kneaded at 170 ° C. Subsequently, the skin layer forming resin is led out from the skin layer forming extruder 71 to the resin supply path of the skin layer forming mold 72, and the skin layer 13 having a thickness of 200 μm is further formed around the pipe 11 covered with the foam tube 2. The coated pipe 1 covered with the thickness was taken up by the third take-up machine 73 and taken up by the take-up machine.
[0143]
(Example 2)
Before introducing the pipe 11 covered with the foaming tube 2 into the foaming tube reducing device 63, a cut fusion step is provided, the heater temperature of the hot air supply device is set to 200 ° C., and the surface layer of the cut 21 is passed through the hot air nozzle 81. After the resin was continuously melted, a coated pipe was manufactured in the same manner as in Example 1 except that the resin was introduced into the foam tube reducing device 63 to continuously fuse the cuts 21.
In Example 2, since the cuts 21 were continuously fused, it was possible to reliably prevent the cuts 21 from separating when the skin layer 13 was formed.
[0144]
(Example 3)
Example 2 except that the fan of the hot air supply device was turned on and off every 10 seconds to melt the gap 21 intermittently, and then introduced into the foam tube reducing device 63 to fuse the gap 21 intermittently. A coated pipe was produced in the same manner as in Example 2.
In Example 3, the cuts 21 were intermittently fused, but the cuts 21 could be surely prevented from separating when the skin layer 13 was formed.
[0145]
(Example 4)
Example 4 used the manufacturing apparatus in the third embodiment (FIG. 15) described above. The foamed tube 2 is wound up in advance on a reel or the like, and as shown in FIG. 15, these are unwound, and the foaming tube 2 is sent out to the foamed layer forming process section 33 by a take-off machine in the same manner as in Example 1. To produce a coated pipe.
Since the foam tube 2 manufactured in advance and wound on a reel or the like is used, the heat generated at the time of forming the cut 21 can be reduced as compared with the case where the foam tube 2 is manufactured in-line. I was able to increase the line speed at the time.
[0146]
(Example 5)
In Example 5, the manufacturing apparatus according to the above-described fourth embodiment (FIG. 16) was used. As shown in FIG. 16, without extruding a preformed pipe, a polyethylene pipe having an outer diameter of 17 mm is manufactured by an extrusion line arranged in parallel, and a foam layer forming step is continuously performed by a second take-off machine 52. A coated pipe was manufactured in the same manner as in Example 1 except that the pipe was sent to the section 33.
Since the pipe 11 and the foam tube 2 can be formed in-line, the manufacturing cost can be reduced.
[0147]
(Comparative Example 1)
A crosshead die was connected to the foam extruder used in Example 1, and a long land die (10 times the pipe outer diameter) having a length of 170 mm was connected to the crosshead die. An extruder for extruding the bed resin was connected, and a tank, a pump, and a conduit were connected so that a lubricant could be supplied to an inlet of the long land die.
Resin composition pre-weighed and pre-blended in a hopper of a foam extruder used in Example 1 so that 100 parts by weight of low-density polyethylene and 1.5 parts by weight of body-designated PP'-oxybis- (benzenesulfonylhydrazide) are used. The material was supplied and extrusion was started. At this time, the gas supply port was not used with a blind plug.
At the same time, a resin composition pre-measured and pre-blended so that carbon black was 2.0 parts by weight with respect to 100 parts by weight of high-density polyethylene was supplied to an extrusion hopper for extruding a skin layer resin, and extrusion was started. At this time, a crosslinked high-density polyethylene pipe having an outer diameter of 17 mm was supplied to the crosshead die using the pipe feeding machine used in Example 1. Further, foam cooling was performed in the long land die using a long land die, and a foam layer and a skin layer were simultaneously formed on the outer periphery of the pipe at the outlet of the long land die. At this time, the lubricant polyoxymethylene-polyoxypropylene copolymer was supplied to the entrance of the long land die.
[0148]
The thickness of the foam layer of the coated pipe obtained as described above was 3 mm, and the thickness of the skin layer was 0.2 mm. As a result, only a coated pipe having an expansion ratio of about 2 was obtained.
[0149]
Further, the contracted state of the foam tube 2 when using the enlarged core 62a shown in FIGS. 6 and 7 and when using the enlarged core 62a shown in FIG. 8 were compared. When the expanded core 62a shown in FIGS. 6 and 7 is used, the shrinkage at the cut end when the coated pipe is cut after forming the coated pipe with respect to the tube length (1000 mm) of the foamed tube immediately before the cut is formed. When the expanded core 62a shown in FIG. 8 was used while the dimension was 15 mm, the coated pipe after forming the coated pipe was cut for the tube length (1000 mm) of the foamed tube immediately before the cut was formed. The shrinkage dimension at the cut end at that time was 1 mm.
[0150]
From the above results, as shown in FIG. 8, by forming the concave portion 62g for reducing the contact area with the inner surface of the foam tube 2 in the expanded core 62a, the expansion of the foam tube 2 due to frictional heat can be reduced, The shrinkage of the foam tube 2 after the formation of the coated pipe was able to be suppressed.
[0151]
【The invention's effect】
As described above, according to the coated pipe of the present invention, the foam layer is formed in a tubular shape, and the tubular foam layer has a cut extending in the longitudinal direction for inserting the pipe into the inside of the tube. Since the continuous skin layer is formed on the outer periphery of the cut foam layer, the foam layer having a uniform high foaming can be obtained, and the end portions of the coated pipe in the axial direction, such as a connection work between the coated pipes. When the foam layer must be removed from the pipe in the above, the foam layer can be easily peeled off from the cut portion, so that the connecting operation of the coated pipe becomes easy.
[0152]
Furthermore, according to the production method and the production apparatus of the present invention, the outer periphery of the pipe can be uniformly coated with the highly foamed foam layer, and furthermore, the coated pipe having the outer periphery covered with the skin layer can be efficiently produced. , And can be manufactured at low cost.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram of a manufacturing apparatus for manufacturing a coated pipe according to a first embodiment of the present invention.
FIG. 2 is a cross-sectional view of a foam tube manufactured in a foam tube manufacturing step in the method for manufacturing a coated pipe of the present invention.
FIG. 3 is a cross-sectional view of a foam tube in a state where a cut is formed in a slit forming step in the method for manufacturing a coated pipe of the present invention.
FIG. 4 is a cross-sectional view of a pipe in a state where a foam layer is formed on the outer periphery of the pipe through a diameter reducing step after the pipe is inserted into the foam tube in the pipe inserting step in the pipe inserting step in the method of manufacturing a coated pipe of the present invention. is there.
FIG. 5 is a cross-sectional view of a coated pipe manufactured by the method for manufacturing a coated pipe of the present invention.
FIG. 6 is a perspective view showing a nick forming device and a diameter-expanding core of a pipe insertion device in a manufacturing apparatus for manufacturing a coated pipe.
FIG. 7 is a perspective view showing another embodiment of a cut forming apparatus in a manufacturing apparatus for manufacturing a covered pipe and an enlarged core of a pipe inserting apparatus.
FIG. 8 is a perspective view showing another embodiment of the expanded core of the pipe insertion device in the manufacturing apparatus for manufacturing a covered pipe.
9 is a sectional view taken along line XX in FIG.
FIG. 10 is a perspective view showing another embodiment (linear enlarged core) of the enlarged core of the pipe insertion device in the production apparatus for producing the coated pipe.
FIG. 11 is a perspective view showing another embodiment of the expanded core of the pipe insertion device in the manufacturing apparatus for manufacturing the coated pipe (the foamed tube and the pipe are fitted while bending and expanding with a bent-type expanded core). It is.
FIG. 12 is an overall configuration diagram of a manufacturing apparatus for manufacturing a coated pipe according to a second embodiment of the present invention.
FIG. 13 shows a cross-sectional view of a concave roller and a schematic view of a hot-air nozzle of a foam tube reducing device used in a manufacturing apparatus according to a second embodiment.
FIG. 14 is a cross-sectional view of a method of manufacturing a coated pipe according to the present invention, in which a pipe is inserted into a foam tube in a pipe inserting step, and a cut is formed in a state where a foam layer is formed on the outer periphery of the pipe through a diameter reducing step; It is a pipe sectional view of the state where it was worn.
FIG. 15 is an overall configuration diagram of a manufacturing apparatus for manufacturing a covered pipe according to a third embodiment of the present invention.
FIG. 16 is an overall configuration diagram of a manufacturing apparatus for manufacturing a coated pipe according to a fourth embodiment of the present invention.
[Explanation of symbols]
1 Insulated pipe
11 pipe
12 Foam layer
13 Skin layer
2 Foam tube
21 cut
31a Foam tube production process department
41 Extruder for foam tube molding
42 foam mold
61a, 61i cutter blade
62a expanded core
63a cylindrical body
71 Extruder for skin layer molding
72 Mold for forming skin layer

Claims (19)

A foam pipe is formed on the surface of the pipe, and further, a coated pipe having a skin layer formed on the outer periphery of the foam layer,
The foam layer is formed in a tubular shape and has a cut extending in a longitudinal direction,
The coated pipe, wherein the skin layer has continuity without a cut extending in a longitudinal direction. The coated pipe according to claim 1, wherein the cuts extending in the longitudinal direction of the foam layer are intermittently fused. A foam layer is formed on the pipe surface, and further a method for producing a coated pipe in which a skin layer is formed on the outer periphery of the foam layer,
A slit forming step of continuously making a cut in the longitudinal direction while continuously supplying a foam tube to be a foam layer,
A pipe insertion step of inserting a pipe into the foam tube from the cut while expanding the diameter of the cut foam tube,
A foam tube reducing step of reducing the diameter of the foam tube in which the pipe is inserted,
A method for forming a skin layer on the outer periphery of a foamed tube whose diameter has been reduced by inserting a pipe. The method for manufacturing a covered pipe according to claim 3, wherein the slit forming step includes a foam tube manufacturing step of extruding the foam tube to continuously supply the foam tube. The foaming tube manufacturing step is characterized in that the molten resin mixed with the physical foaming agent is sent to a foaming mold in a state where the pressure is reduced from the foaming tube molding extruder, and the foamed mold is released to the atmospheric pressure. Item 5. A method for producing a coated pipe according to Item 4. The method according to claim 5, wherein the physical foaming agent is carbon dioxide. The method for producing a coated pipe according to any one of claims 4 to 6, wherein the expansion ratio of the expanded tube formed by extrusion foaming in the expanded tube manufacturing step is 5 times or more. The manufacturing of the coated pipe according to any one of claims 3 to 7, wherein the slit forming step is performed by rotating a rotatable circular cutter in the same direction as the traveling direction of the foam tube. Method. In the pipe insertion step, the foamed tube with a cut is introduced into the enlarged core having a tapered tapered upstream side in the feed direction of the foamed tube, and the foamed tube is conveyed while being expanded while being conveyed. The method for producing a coated pipe according to any one of claims 3 to 8, wherein the pipe is inserted from a cut extending into the foam tube. The method for producing a coated pipe according to any one of claims 3 to 9, wherein the pipe inserting step includes a cooling step of cooling the expanded foam tube. In the foam tube reducing step, the foam tube in which the pipe is inserted is fed into the inside of the tubular body in which the downstream side in the feed direction of the foam tube is tapered, and the cut portion of the foam tube is joined to reduce the diameter of the foam tube. The method for producing a coated pipe according to any one of claims 3 to 10, wherein the method comprises: In the foam tube reducing step, a pair of rotatable rollers having a tapered outer peripheral surface with a concave central portion in the axial direction is used, and the expanded foam tube is introduced between the two rollers to form a roller pair. The method for manufacturing a coated pipe according to any one of claims 3 to 10, wherein the diameter of the foamed tube is reduced by pressing in a direction in which opposing surfaces of cuts of the foamed tube are brought into contact with each other. The method according to claim 3, further comprising a step of fusing the opposing surfaces of the cuts of the reduced-diameter foam tube after the step of reducing the diameter of the foam tube and before the step of forming the skin layer. 14. The method for producing a coated pipe according to any one of the above. 14. The method for manufacturing a coated pipe according to claim 13, wherein, in the cut fusion step, the surface layer resin at the cut portion of the foamed tube is melted by hot air to fuse the opposing surfaces of the cut. In the skin layer forming step, the foamed tube into which the pipe is inserted and whose diameter is reduced is fed to the skin layer forming mold, and the skin layer forming resin melted from the skin layer forming extruder is used for the skin layer forming mold. The method for producing a coated pipe according to any one of claims 3 to 14, wherein a skin layer is formed on the outer periphery of the foamed tube by extrusion. A foamed layer is formed on the surface of the pipe, and further, a coated pipe manufacturing apparatus in which a skin layer is formed on the outer periphery of the foamed layer,
A slit forming process section that continuously cuts the foam tube in the tube longitudinal direction while continuously supplying the foam tube to be the foam layer,
A pipe insertion process section for inserting a pipe into the foam tube from the cut while expanding the diameter of the cut foam tube,
A foam tube reducing step for reducing the diameter of the foam tube in which the pipe is inserted,
And a skin layer forming step for forming a skin layer on the outer periphery of the foamed tube having the diameter reduced by inserting the pipe. 17. The coated pipe manufacturing apparatus according to claim 16, wherein the slit forming section includes a rotatable circular cutter and cooling equipment for the circular cutter. The pipe insertion process section has a taper whose upstream side in the feeding direction of the foaming tube has a tapered shape, and includes a diameter-enlarging core that expands the foamed tube with a cut. 18. The coated pipe according to claim 16 or 17, further comprising a contact recess, and a guide passage for inserting the pipe into the foam tube from a cut of the foam tube expanded by expanding the diameter. manufacturing device. The apparatus for manufacturing a coated pipe according to any one of claims 16 to 18, wherein the pipe insertion processing unit includes a cooling mechanism for cooling the expanded foam tube.

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