JP2003130257A - Photo-curing conductive paint composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an insulating pipe having a uniformly and highly foamed foam body layer on the outer periphery thereof, and a method of efficiently manufacturing, at a low cost, the insulating pipe having the uniformly and highly foamed foam body layer formed on the outer periphery thereof and having the surface layer covered on the outer periphery thereof. SOLUTION: A method of manufacturing the insulating pipe comprises a slit formation step for continuously slitting a foam tube in the longitudinal direction of the tube while continuously feeding the foam tube forming the foam body layer, a pipe insertion step for inserting the pipe into the foam tube from a slit while expanding the diameter of the slit foam tube, a foam tube diametrally reducing step for diametrally reducing the foam tube having the pipe inserted therein, and a surface layer forming step for forming a surface layer on the outer periphery of the foam tube diametrally reduced by the insertion of the pipe therein.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat insulating pipe having a foam layer formed on the surface of the pipe and a skin layer formed on the outer periphery of the foam layer, and a method for manufacturing the heat insulating pipe.

[0002]

2. Description of the Related Art Conventionally, for the purpose of imparting heat insulating properties to a pipe, for example, a synthetic resin pipe, a copper pipe, a steel pipe, etc., the outer periphery of the pipe has been covered with a foam layer formed of a foam synthetic resin composition. Insulated pipes are used.

However, since the foam layer has low frictional strength and scratching strength, if the foam layer is exposed to the outside, there is a problem that it is easily damaged by friction or scratching during construction or after piping.

Therefore, for the purpose of protecting the surface of the foam layer, it has been proposed that a skin layer formed of a non-foaming synthetic resin is further formed on the outer peripheral surface of the foam layer.

For example, Japanese Patent Application Laid-Open No. 61-293825 discloses a method for producing an adiabatic pipe using an extruder, in which a foam layer is formed on the surface of the pipe and a skin layer is formed on the outer periphery of the foam layer. It is disclosed. In this manufacturing method, a long land die is used for the die of the extruder, and the foam layer-forming composition and the skin layer-forming resin are supplied to the head of the extruder 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.

[0006]

However, JP-A-61-161
In the manufacturing method disclosed in Japanese Patent No. 293825, since foaming is performed in the long land die and cooling is performed in the long land die, foaming of the foam layer is performed between the outer surface of the pipe and the long land die. The shape is fixed by being cooled in the long land die while being restricted by the inner surface and foaming being restricted.

Therefore, when a thermal decomposition type chemical foaming agent is used, it is cooled before it is completely decomposed by heat, so that the gas pressure of the foaming agent dissolved in the resin is lowered and the expansion ratio is increased. Was only about double.
Further, even when using a physical foaming agent, the resin composition of the foam layer is foamed in a state where foaming in the thickness direction is restricted by the long land die and the pipe, and when it comes out from the long land die, Since the foam layer had been covered with the skin layer that had been cooled and fixed, a high expansion ratio could not be obtained.

Further, since the conventional heat-insulating pipe is formed by extruding the foam layer and the skin layer on the outer periphery of the pipe at the same time, the foam layer is brought into close contact with the entire outer peripheral surface of the pipe, and a plurality of layers are formed. When connecting the heat-insulating pipe, it is necessary to peel off the foam layer at the end of the heat-insulating pipe, but there is also a problem that the peeling work is difficult because the foam layer adheres too much to the outer peripheral surface of the pipe.

The present invention is intended to solve the problems in the method of manufacturing a heat insulating pipe having a foam layer and a skin layer, and while forming a highly foamed foam layer uniformly on the outer periphery of the pipe, In addition to providing a heat-insulating pipe that can easily remove the foam layer from the pipe, a highly foamed foam layer can be uniformly formed on the outer circumference of the pipe, and a heat-insulating pipe covered with a skin layer on the outer circumference can be efficiently used. An object is to provide a good and inexpensive manufacturing method.

[0010]

In order to achieve the above object, the invention according to claim 1 is a heat insulation in which a foam layer is formed on the surface of a pipe, and a skin layer is formed on the outer periphery of the foam layer. In the pipe, the foam layer is formed in a tubular shape, the tubular foam layer is formed with a cut extending in the longitudinal direction for inserting the pipe into the cylinder, and a foam layer having a cut is formed. It is characterized in that a continuous skin layer is formed on the outer periphery.

The pipe used in the present invention is a pipe having a heat insulating property, and is, for example, a metal pipe such as a steel pipe or a copper pipe, a polyolefin pipe such as polyethylene, polypropylene or polybutene-1, or a cross-linked polyethylene pipe. Examples include synthetic resin pipes such as cross-linked polyolefin pipes.

The foam layer coated on the outer periphery of the pipe is made of a foamed resin composition containing a thermoplastic resin which can be foamed in a low pressure zone by a foaming agent. Examples of the thermoplastic resin include polyethylene, polypropylene, Extrudable thermoplastics such as polystyrene, vinyl chloride, vinylidene chloride, ethylene-vinyl acetate copolymer, chlorinated polyethylene, ethylene-propylene copolymer, ethylene-ethyl acrylate copolymer, polyethylene terephthalate, ABS resin, acrylic resin Examples thereof include resins, and these may be used alone or in combination of two or more kinds.
The skin layer coated on the outer periphery of the foam layer is preferably an extrudable resin and is a thermoplastic resin having scratch resistance.

According to the first aspect 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 cylinder. Since a continuous skin layer is formed on the outer periphery of the foam layer having cuts, the foam layer having a high degree of foaming can be obtained uniformly, while connecting the heat insulating pipes, etc. When the foam layer has to be removed from the pipe in (1), the foam layer can be easily peeled from the cut portion, so that the work of connecting the heat insulating pipe becomes easy.

The invention described in claim 2 is the same as claim 1
In the invention of the heat-insulating pipe described in (1), the breaks in the tubular foam layer are intermittently fused. Intermittent fusing of the breaks means that there are fused parts and unfused parts along the breaks.

According to the second aspect of the present invention, since the cuts of the tubular foam layer are intermittently fused, the cuts at the time of forming the skin layer at the fused portion. While preventing the opening, the foam layer can be easily peeled from the pipe in the unfused portion of the break.

A third aspect of the present invention is a method for producing a heat insulating pipe in which a foam layer is formed on the surface of the pipe, and a skin layer is formed on the outer periphery of the foam layer, which is the foam layer. A slit forming process in which a foam tube is continuously supplied while making continuous cuts in the foam tube in the longitudinal direction of the foam tube, and a pipe that inserts a pipe into the foam tube from the break while expanding the diameter of the cut foam tube. A heat insulating pipe is formed by an inserting step, 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 being manufactured.

As a means for supplying the foam tube, a foam tube which is a foam layer produced in advance may be wound on a reel or the like and supplied to the slit forming step, or the foam tube manufacturing step. May be provided so that the manufactured foam tube is directly supplied to the slit forming step.

According to the third aspect of the present invention, 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 produced, and then the foam tube is formed. Since the pipe is covered with the foam tube by forming a cut in the foam tube and inserting the pipe into the foam tube, a foam layer having a high degree of uniform foam can be obtained.

According to a fourth aspect of the present invention, in the method of manufacturing a heat insulating pipe according to the third aspect, the slit forming step is a foaming process in which the foaming tube is independently extruded for continuously supplying the foaming tube. It is characterized by having a tube manufacturing process section. The foam layer coated on the outer circumference of the pipe is made of a foamed resin composition containing a thermoplastic resin that can be foamed in the low-pressure zone by a foaming agent, as described above. When 2 to 3 parts by weight of the cell nucleating agent is added, the cells of the obtained foam become fine and the heat insulation performance is improved.

The foaming agent for foaming the thermoplastic resin is not particularly limited as long as it does not deteriorate the thermoplastic resin, and for example, a thermal decomposition type foaming agent such as azodicarbonamide, benzenesulfonyl hydrazide, toluenesulfonyl hydrazide, or the like. Mention may be made of physical blowing agents which are gases or volatile liquids under pressure. According to the invention described in claim 4, the series of steps for manufacturing the heat insulating pipe can be performed in-line, so that the heat insulating pipe can be efficiently manufactured at low cost.

According to a fifth aspect of the present invention, in the method for producing a heat insulating pipe according to the fourth aspect, the foam tube manufacturing step section extrudes a molten resin mixed with a physical foaming agent from the foam tube molding extruder. And is sent to a foaming mold connected to an extruder for forming a foaming tube, and the foaming mold is released to atmospheric pressure to manufacture a foaming tube.

The physical foaming agent includes nitrogen, carbon dioxide, air and the like as gas, and the low boiling point aliphatic hydrocarbons such as propane, butane and pentane, alcohols, ketones and esters as easily volatile liquids. Examples thereof include low boiling point organic compounds such as compounds, halogenated hydrocarbons such as monochlorodifluoromethane, dichlorodifluoromethane, and dichlorotetrafluoroethane. These may be used alone or in combination of two or more kinds. . According to the fifth aspect of the present invention, the foam tube is exposed to the atmosphere by the physical foaming agent and foam-molded, so that the foaming can be uniformly performed while the predetermined expansion ratio is obtained.

The invention according to claim 6 is characterized in that, in the method for producing an adiabatic pipe according to claim 5, the physical foaming agent supplied to the molten resin in the foam tube molding extruder is carbon dioxide gas. To do. When using an easily volatile liquid as a physical foaming agent, there is a possibility that the ozone layer may be destroyed or it is flammable, so many facilities require explosion-proof specifications, but carbon dioxide gas is used as a physical foaming agent. As a result, there is no possibility of depleting the ozone layer, the load on the environment can be reduced, and because it is nonflammable, explosion-proof specifications are not required as equipment, and the equipment becomes simple. Further, it has high solubility in resin.

The invention according to claim 7 is the method for producing a heat insulating pipe according to any one of claims 4 to 6, wherein the expansion ratio of the foamed tube extruded and foamed in the foamed tube manufacturing step is 5 It is characterized by being more than double.

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 preferred expansion ratio of the foam layer is 5 times or more is up to 5 times. The reason is that the higher the magnification is, the more rapidly the thermal conductivity is lowered and the heat insulation performance is improved. Incidentally, in the resin composition forming the foam layer or the skin layer, if necessary, a stabilizer, an antioxidant, a processing aid, a lubricant, a foaming aid, a filler, a pigment, a flame retardant, etc. are added. be able to.

The invention according to claim 8 is the method for manufacturing an adiabatic pipe according to any one of claims 3 to 7, wherein the slit forming step includes cooling the foam tube and / or a cutter blade for forming a cut line. It has a cooling step for performing. According to the invention of claim 8, in the slit forming step, since the foam tube and / or the cutter blade for forming the slit is cooled, the foam tube has residual heat due to extrusion molding, and the cutter blade has friction heat. It is possible to suppress the temperature rise of the cut portion at the time of forming the cut portion due to the occurrence of cracks, and prevent the cut formation failure due to the temperature rise of the cut portion.

According to a ninth aspect of the present invention, in the method for manufacturing a heat insulating pipe according to any of the third to eighth aspects, in the pipe inserting step, a taper is formed on the upstream side of the foam tube in the feed direction. Introducing a notched foam tube into the diameter-expanding core having, and expanding the diameter while conveying the foam tube, and inserting the pipe from the notched slit in the foam tube to be conveyed. It is a thing. According to the invention of claim 9,
The expanded core makes it easy to widen the cuts in the foam tube, making it easier to insert the pipe into the foam tube.

According to a tenth aspect of the present invention, in the method for manufacturing a heat insulating pipe according to any of the third to ninth aspects, the pipe inserting step includes a cooling step of cooling the foamed tube to be expanded in diameter. It is characterized by doing.

While continuously feeding the foam tube,
When the pipe is inserted into the foam tube, the temperature of the inner and outer surfaces of the foam tube may rise and the foam tube may expand if the amount of the foam tube fed out increases. When expansion occurs in the foam tube, the foam tube shrinks after the skin layer is formed, and the pipe end of the pipe is largely exposed after manufacturing the heat-insulating pipe, or when the heat-insulating pipe is cut midway. Also in the case, the phenomenon that the pipe is largely exposed at the cutting portion occurs.

According to the tenth aspect of the present invention, the foamed tube can be cooled in the cooling step in the pipe inserting step even if the amount of the foamed tube fed out increases, so that the temperature rise of the foamed tube is suppressed and the foamed tube is suppressed. Can be prevented and the pipe can be prevented from being exposed from the end of the heat insulating pipe.

The invention described in claim 11 is the method for manufacturing a heat insulating pipe according to any one of claims 3 to 10, wherein the step of reducing the diameter of the foamed tube is tapered on the downstream side in the feed direction of the foamed tube. The foamed tube in which the pipe is inserted is fed into the inside of the tubular body, and the cut portion of the foamed tube is joined to reduce the diameter of the foamed tube. According to the invention as set forth in claim 11, the diameter of the foamed tube expanded by the tubular body can be easily reduced.

According to a twelfth aspect of the present invention, in the method for producing a heat insulating pipe according to any one of the third to tenth aspects, in the step of reducing the diameter of the foam tube, a taper-shaped outer periphery having a depressed central portion in the axial direction. Using a pair of rotatable rollers having a surface, introduce a foam tube expanded in diameter between two rollers, and press in the direction in which the facing surfaces of the cuts of the foam tube are brought into contact with each other by the roller pair. It is characterized by reducing the diameter.

According to the twelfth aspect of the invention, the rotatable 1 having the tapered outer peripheral surface with the axial center recessed
By using a pair of rollers, it is possible to easily reduce the diameter of the expanded foam tube. Furthermore, since the diameter of the foam tube can be reduced without applying tension to the foam tube, it is possible to prevent the foam tube from shrinking when the heat insulating pipe is cut, and stabilize the product dimensions. Can be achieved.

According to a thirteenth aspect of the invention, in the method for producing a heat insulating pipe according to any of the third to twelfth aspects, the diameter is reduced after the pipe inserting step and before the skin layer forming step. It is characterized in that it has a break fusion step of fusing the opposing surfaces of the break of the foamed tube. As a method for fusing the opposing surfaces of the cuts of the foamed tube, there are a method of continuously fusing the cuts in the length direction and a method of intermittently fusing along the breaks.

According to the thirteenth aspect of the present invention, since the cuts are fused before the skin layer is formed, it is possible to reliably prevent the cut portion from opening during the formation of the skin layer, and to improve the quality. It can prevent the deterioration.

According to a fourteenth aspect of the present invention, in the method for producing a heat insulating pipe according to the thirteenth aspect, in the break fusion step, the surface layer resin in the break portion of the foam tube is melted by hot air to face the cut surface. It is characterized in that they are fused together. According to the invention as set forth in claim 14, the cut portion can be fused by a simple method without directly contacting the heat source and causing the foam tube to lose its shape.

The invention according to claim 15 is the method for producing a heat insulating pipe according to any one of claims 3 to 14, wherein in the skin layer forming step, the pipe is inserted to reduce the diameter of the foamed tube. It is characterized in that, while being fed into the skin layer forming die, the melted skin layer forming resin is extruded from the skin layer forming extruder into the skin layer forming die to form a skin layer on the outer periphery of the foam tube. It is a thing.

If the thickness of the skin layer is too thin, the surface of the foam layer cannot be completely protected due to friction or scratching.
The thickness is preferably 00 μm or more, and more preferably 200 μm or more. In addition, since it is highly likely that the unevenness of the foam surface is transferred to the skin layer, a pigment having a concealing property is added to the resin in order to improve the appearance, or embossing or embossing is performed. Is preferred. According to the fifteenth aspect of the present invention, the skin layer can be easily formed on the outer periphery of the foam tube in which the pipe is inserted and the diameter of which is reduced.

The invention as set forth in claim 16 is an apparatus for producing a heat insulating pipe in which a foam layer is formed on the surface of the pipe, and a skin layer is formed on the outer periphery of the foam layer, which is the foam layer. Insert the pipe into the foam tube through the slit while expanding the diameter of the slit forming process part and the slit forming process part that continuously cuts the foam tube in the longitudinal direction of the foam tube while continuously supplying the foam tube A pipe insertion step part, a foam tube diameter reducing step part for reducing the diameter of the foam tube in which the pipe is inserted, and a skin layer forming step part for forming a skin layer on the outer circumference of the foam tube in which the pipe is inserted and reduced in diameter. It is characterized by having.

According to the apparatus for producing a heat-insulated pipe of the sixteenth aspect, the foam layer covering the surface of the pipe is not directly formed on the outer surface of the pipe, but is formed on the foam tube after production which becomes the foam layer. By forming a cut and inserting the pipe into the foam tube, the pipe is covered with the foam tube, and it is possible to manufacture an adiabatic pipe in which a skin layer is formed on the outer periphery of the foam tube, so that the foam is uniformly and highly foamed. An insulating pipe with a foam layer is obtained.

According to a seventeenth aspect of the present invention, in the heat insulating pipe manufacturing apparatus according to the sixteenth aspect, the pipe insertion step portion has a taper on the upstream side in the feed direction of the foam tube, and has a break. Equipped with a diameter-expanding core that expands the diameter of the foam tube inside.The diameter-expansion core has a recess on the outer surface that is not in contact with the foam tube, and inserts a pipe into the foam tube through the cut of the foam tube expanded by diameter expansion. It is characterized in that it is provided with a guide passage for making it.

The concave portion provided in the diameter-expanding core is formed by forming a plurality of annular concave grooves extending in the circumferential direction on the surface of the diameter-expanding core, forming a spiral groove on the surface of the diameter-expanding core, or feeding the foam tube. It can be obtained by forming a plurality of recessed grooves extending to.

According to the seventeenth aspect of the invention, the diameter of the foam tube is expanded while the inner surface of the foam tube is aligned with the taper outer peripheral surface of the expanded core, and the pipe is expanded from the guide passage of the expanded core. It can be easily inserted into the tube. Moreover, since the recessed 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, friction can be reduced. It is possible to reduce the temperature rise of the foam tube due to friction while smoothly expanding the diameter with the diameter-expanding core.

The invention described in claim 18 is the apparatus for manufacturing an adiabatic pipe according to claim 16 or claim 17, wherein the pipe insertion step portion is provided with a cooling mechanism for cooling the expanded foam tube. It was configured. According to the eighteenth aspect of the present invention, the foamed tube can be cooled by the cooling mechanism in the pipe insertion step even if the amount of the foamed tube delivered is increased, so that the temperature rise of the foamed tube is suppressed and the expansion of the foamed tube is suppressed. Can be prevented, and the pipe can be prevented from being exposed from the pipe end portion of the heat insulating pipe after manufacturing.

[0045]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 schematically shows a first embodiment of a manufacturing apparatus for manufacturing a heat insulating pipe by the method for manufacturing a heat insulating pipe of the present invention. The heat insulating pipe manufacturing apparatus shown in FIG. The pipe 1 can be manufactured. The heat insulating pipe 1 is, as shown in FIG.
A foam layer 12 serving as a heat insulating layer is formed on the surface of the pipe 11, and a skin layer 13 is further formed on the surface of the foam layer 12.

The heat insulating pipe manufacturing apparatus of the first embodiment is
The foam tube 2 that will become the foam layer 12 shown in FIG.
As shown in, the cut 21 is continuous in the longitudinal direction of the tube.
And a slit forming process section (slit forming process)
While expanding the diameter of the foam tube 2 having the cut 21, the pipe inserting step (pipe inserting step) for inserting the pipe 11 from the cut 21 into the foam tube 2 and the diameter of the foam tube 2 in which the pipe 11 is inserted are reduced. Foam tube reducing step (foam tube reducing step)
And the foam tube 2 with the diameter reduced by inserting the pipe 11.
The heat insulating pipe 1 is manufactured through each manufacturing process of the skin layer forming process part (skin layer forming process) in which the skin layer 13 is formed on the outer periphery of the heat insulating pipe 13 to the state shown in FIG. The slit forming process section also has a foam tube supply process for continuously supplying the foam tube 2.

The heat insulating pipe manufacturing apparatus of the first embodiment is
As shown in FIG. 1, the foamed tube supply step is configured by a foamed tube manufacturing step section 31a for independently extruding and molding the foamed tube 2. In addition, between the pipe insertion step and the foam tube diameter reduction step, a heating portion 81 shown by a virtual line in FIG. 1 is provided to intermittently connect the opposing surfaces of the cut 21 of the foam tube 2 into which the pipe is inserted, Alternatively, there may be provided a break fusion step of continuously fusion bonding.

In this case, it is preferable that the heating section is constituted by a hot air nozzle 81 for blowing hot air onto the foam tube 2. Since the specific configuration and operational effects are the same as those of the heating unit shown in the second embodiment described later, the second configuration
This will be described in the embodiment.

The heat insulating pipe manufacturing apparatus according to the first embodiment will be specifically described. As shown in FIG. 1, the heat insulation pipe manufacturing apparatus according to the first embodiment repeats a flexible tube 11 and a foam tube manufacturing process section 31 a for independently extruding and molding the foam tube 2 to be the foam layer 12. A pipe feeding process unit 32a, a foam layer forming process unit 33 that performs a slit forming process, a pipe inserting process, and a foam tube reducing process, and a skin layer forming process unit 3 that performs a skin layer forming process.
4 and.

The foamed tube manufacturing process section 31a comprises a foamed tube molding extruder 41 in which a foamable thermoplastic resin composition for forming the foamed layer 12 is melt-kneaded, and a foamed tube molding extruder 41. The foamed metal mold 42 for molding the foamed tube 2 into which the melted resin is injected.
And a first take-off machine 43 for receiving the foam tube 2 coming out of the foam mold 42.

The extruder 41 for forming a foam tube is provided with a raw material hopper 41a to which the thermoplastic resin composition is supplied and a foaming agent supply section 41b, and a resin for forming the foam layer 12 from the raw material hopper 41a. While supplying the composition, the physical foaming agent in the cylinder 44 is supplied into the foaming tube molding extruder 41 from the foaming agent supply section 41b.

A cooling device 45 and a metering pump 46 are provided in the supply path between the cylinder 44 and the foaming agent supply section 41b. Since carbon dioxide is used as the physical foaming agent in this embodiment, In order to improve the supply efficiency, a cooling device 45 is provided in front of the metering pump 46, and carbon dioxide gas is liquefied in the cooling device 45 and supplied to the metering pump 46.

Further, in the metering pump 46, the supply amount of the foaming agent into the foaming tube molding extruder 41 is set so that a desired foaming ratio can be obtained with respect to the resin extrusion amount of the foaming tube molding extruder 41. Have control over.

The expansion ratio can be controlled by the amount of the foaming agent dissolved in the molten resin. When carbon dioxide gas is used as the physical foaming agent, in order to obtain an expansion ratio of 5 times or more, 1% by weight or more of carbonic acid in the molten resin is used. It is necessary to dissolve the gas.

However, if carbon dioxide gas is supplied in excess of the target magnification, bubble breakage will occur at the outlet of the foaming mold 42, and gas escape will be promoted. As a result, the magnification will not increase and bubble breakage will occur. It is necessary to control the amount of foaming agent supplied so that it does not exist.

In the foam tube molding extruder 41, the foaming agent is melted in the molten resin from the foaming agent supply section 41b while heating and melting the resin composition supplied from the raw material hopper 41a to form the foam tube. The molten resin is extruded into the foaming mold 42 connected to the extrusion extruder 41.

Further, in the foaming tube molding extruder 41, the foaming tube supplying extruder 41b is provided in the foaming tube molding extruder 41 so that the foaming agent can be stably supplied into the foaming tube molding extruder 41. The groove depth of the screw is formed so as to be deep at a portion facing the position where the foaming agent supply section 41b is formed, and the pressure of the molten resin is once reduced when the foaming agent is supplied.
In addition, 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 dullage.

Although not shown, the foaming mold 42 is composed of an inner core and an outer mold for molding in a tube shape, the inner core is held by a bridge, and the outer mold is a band heater or oil. The temperature can be adjusted by the medium.

The first take-up machine 43 is composed of a pair of first conveyor belts 43a which are rotationally driven. The first conveyor belt 43a sandwiches the foam tube 2 and the first conveyor belt 43a is rotationally driven. The foam tube 2 is sent to the foam layer forming process unit 33.

Therefore, in the foaming mold 42, the temperature of the resin composition supplied from the foaming tube molding extruder 41 is adjusted to the optimum foaming temperature, and the resin composition in the tube state from the foaming mold 42 is at atmospheric pressure. When released inside, the resin composition is foamed, and a uniform highly foamed foam tube 2 as shown in FIG. 2 is manufactured.

The optimum foaming temperature varies depending on the amount of the foaming agent dissolved in the molten resin in the plasticizing effect of the resin. Therefore, when the resin is crystalline, the melting point is ± 10 ° C., and when the resin is amorphous, Is preferably set within the range of the glass transition temperature ± 10 ° C. Further, it is preferable that the foaming mold 42 is provided with an uneven thickness adjusting mechanism.

A pipe feeding process unit 32 for feeding the pipe 11
As shown in FIG. 1, a is a payout machine 51 to which a pipe 11 which is manufactured and wound in advance by another extruder is attached.
And a second take-up machine 52 for taking out the pipe 11 from the pay-out machine 51 and sending it to the foam layer forming step section 33, and a curl correction device 5 provided between the pay-out machine 51 and the second take-up machine 52.
3 and 3. Pipe 11 used in the present embodiment
Is made of a flexible synthetic resin pipe and is long.

The feeding device 51 is composed of a rotary drum fixed to bearings, and the second take-up device 52 is composed of a pair of second conveyor belts 52a which are rotationally driven. And the pipe 11 is sent to the foam layer forming process unit 33 by the rotational driving of the second conveyor belt 52a.

The curl correction device 53 corrects a larger or smaller curl on the pipe 11, and as shown in FIG. 1, three correction rollers 53a are arranged alternately. Equipped with these correction rollers 5
The winding tendency of the pipe 11 is corrected by 3a. The straightening roller 53a has a shape in which the center of the roller surface in the longitudinal direction is tapered and recessed.

If the pipe is not flexible,
A straight pipe cut into a predetermined length may be continuously sent to the foam layer forming step unit 33 using a take-off machine, or as in a fourth embodiment shown in FIG. 16 described later, The pipe 11 manufactured in the extrusion line of the pipe manufacturing process section 32b having the pipe molding extruder 54 is taken up by the take-up machine 5
Alternatively, it may be continuously sent out to the foam layer forming process section 33 by the step 2.

Further, in the first embodiment, the feeding step of the pipe 11 is performed in parallel with the above-mentioned foam tube manufacturing step, the slit forming step and the step of expanding the diameter of the foam tube which will be described later.

Further, the foam layer forming process section 33 is provided with a break forming device 61 which continuously cuts the foam tube 2 in the longitudinal direction of the foam tube 2 in the slit forming process (slit forming process section). In the (pipe insertion step part), a pipe insertion device 62 for expanding the diameter of the foam tube 2 while being conveyed and inserting the pipe 11 from the cut 21 widened by the diameter expansion core 62a in the conveyed foam tube 2 is provided. In the foamed tube diameter reducing step (foamed tube diameter reducing step section), a foamed tube diameter reducing device 63 for reducing the diameter of the foamed tube 2 into which the pipe 11 is inserted is provided.

As shown in FIG. 1, the break forming device 61 is fixed to a support plate 64 and is linear and long so that breaks 21 are continuously formed in the foam tube 2 in the extrusion direction (longitudinal direction of the tube). A long cutter blade 61a, a first holding roller 61b provided so as to face the tip of the long cutter blade 61a, a long cutter blade 61a and a first holding roller 61b are attached and fixed to a support plate 64. And a supporting body 61c.

Further, as shown in FIG. 6, the long cutter blade 61a is attached to the support 61c so as to be able to move forward and backward in the radial direction with respect to the foam tube 2, and the long cutter blade 6a.
1a is fixed to a U-shaped holder 61d via a swinging fixing plate 61e, and the holder 61d is supported by a support body 61c so that it can be moved forward and backward with respect to the support body 61c by operating a position adjusting handle 61f. There is. By supporting the long cutter blade 61a so that the support 61c can move forward and backward, the cutting depth can be adjusted according to the thickness of the foam tube 2.

Further, the long cutter blade 61a is fixed to a swinging fixing plate 61e so that the cutting angle into the foam tube 2 can be changed, and the swinging fixing plate 61e is supported by a holder 61d (not shown). ), The angle adjusting dial 61g is attached to the support shaft, and the angle adjusting dial 61g is rotated to swing the swing fixing plate 61e to adjust the angle of the long cutter blade 61a. I am trying to do it.

The adjustment angle can be adjusted to a cutting angle of 30 to 45 degrees with respect to the surface of the foam tube 2. The cutting angle can be adjusted because the appropriate cutting angle changes depending on the surface temperature of the foam tube 2.

Then, the cut forming device 61 uses the cut 2
In forming No. 1, a cooling mechanism for cooling the foam tube 2 and the long cutter blade 61a at the time of forming the cut 21 is provided, and cooling for cooling the foam tube 2 and the long cutter blade 61a during the slit forming process. I have a process. The cooling may be performed by either the foam tube 2 or the long cutter blade 61a, or may be performed simultaneously.

Foam tube 2 and long cutter blade 61
As a means for cooling a, a cooling nozzle 61h is also attached to the support 61c on which the long cutter blade 61a is supported, and the discharge port of the cooling nozzle 61h is opposed to the surface of the foam tube 2 to cool the nozzle 61h. The cooling air discharged from the blower is blown onto the location of the cut 21 of the foam tube 2 to cool the foam tube 2 and the long cutter blade 61a.

The cooling nozzle 61h is provided so as to pass through the position adjusting handle 61f attached to the support 61c, the support 61c, and the holder 61d, and is aligned with the long cutter blade 61a. Is bent. Then, depending on the angle adjustment of the long cutter blade 61a, cooling air is blown directly from the outlet of the cooling nozzle 61h to the tip of the long cutter blade 61a, or slightly upstream of the tip of the long cutter blade 61a. Blow cooling air.

In the first embodiment, since the foam tube 2 and / or the long cutter blade 61a is forcibly cooled, the foam tube 2 in the manufacturing process of the foam tube 2
Even if the extrusion amount increases and the inner and outer surface temperatures of the foam tube 2 rise, or the friction heat of the long cutter blade 61a increases due to the large feed amount of the foam tube 2, the foam tube is formed when the cut 21 is formed. Since it is possible to cool the second cut formation position and / or the long cutter blade 61a, it is possible to prevent defective formation of the cut 21.

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. Then, the foam tube 2 to be conveyed is always positioned in the concave portion of the first holding roller 61b, so that the foam tube 2 is held at a predetermined position. Since the foam tube 2 is held by the first holding roller 61b, the slit 21 can be linearly formed at a predetermined position of the foam tube 2 by the long cutter blade 61a.

The first take-up machine 43 and the break forming device 6
A plurality of guide rollers 47 for guiding the foam tube 2 sent from the first take-up machine 43 to the cut forming device 61 are provided between the first and second take-up machines 43.

When making the break 21,
Not limited to the linear long cutter blade described above, for example, by applying a disc-shaped cutter blade fixed to the bearing to the side surface of the foam tube, and making a cut by rotating the disc-shaped cutter blade. Good.

Cut forming device 6 using a disc-shaped cutter blade
The first embodiment will be described with reference to FIG. 7. Figure 7
A slit forming device 6 using a disc-shaped cutter blade 61i shown in FIG.
1 is the same as that of the cut forming device 61 shown in FIG.

The cut forming device 61 using the disc-shaped cutter blade 61i is the same as the manufacturing device shown in FIG. 1, except that the long cutter blade 61a is replaced with the disc-shaped cutter blade 61i. A support plate 64 similar to 61
The disk-shaped cutter blade 61i, which is fixed to the foamed tube 2 and continuously cuts 21 in the extrusion direction (longitudinal direction of the tube) in the foamed tube 2, and the circumferential tip of the disk-shaped cutter blade 61i. First holding roller 61b provided
And the disc-shaped cutter blade 61i and the first holding roller 61b
Is attached and fixed to the support plate 64.

Further, as shown in FIG. 7, the disk-shaped cutter blade 61i 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. The holder 61d is fixed to the holder 61d via a rotary shaft 61j, and the holder 61d is supported by the support 61c so that the holder 61d can be moved back and forth by operating the position adjusting handle 61f.

Although not shown, the rotary shaft 61j for rotating the disc-shaped cutter blade 61i has one end connected to a motor, and the drive of this motor drives the rotary shaft 61j.
Is rotated to rotate the disc-shaped cutter blade 61i. Furthermore, the disc-shaped cutter blade 61i is
The foam tube 2 is rotated in the same direction as the delivery direction. The cutting depth can be adjusted according to the thickness of the foam tube 2 by supporting the disk-shaped cutter blade 61i so that the support 61c can move back and forth.

Further, the break forming device 61 shown in FIG.
Is provided with a cooling mechanism for cooling the disc-shaped cutter blade 61i when forming the cut 21, and in the slit forming step, the disc-shaped cutter blade 61i is formed.
A cooling step for cooling i is provided.

As a means for cooling the disc-shaped cutter blade 61i, the support 6 which supports the disc-shaped cutter blade 61i is used.
A cooling nozzle 61h is also attached to 1c so that the cooling air discharged from the cooling nozzle 61h is blown near the location where the cut 21 of the foam tube 2 is to be formed to cool the disk-shaped cutter blade 61i.

The cooling nozzle 61h includes a position adjusting handle 61f attached to the support 61c and the support 61c.
The disc-shaped cutter blade 61 by penetrating the holder and the holder 61d.
i is provided so as to cross i, and the cooling nozzle 61 is provided.
Cooling air is blown directly from the discharge port of h to the tip of the disk-shaped cutter blade 61i.

Since the disc-shaped cutter blade 61i is also forcibly cooled by the cut forming device 61 shown in FIG. 7, the foam tube 2 in the manufacturing process of the foam tube 2 is also improved.
Even if the extrusion amount increases and the temperature of the inner and outer surfaces of the foam tube 2 rises, or the frictional heat of the disc-shaped cutter blade 61i increases due to the large feed amount of the foam tube 2, the circle 21 is formed when the cut 21 is formed. Since the plate-shaped cutter blade 61i can be cooled, it is possible to prevent defective molding of the cut 21.

The pipe insertion device 62 of the first embodiment shown in FIG. 1 has a diameter-expanding core 62a for expanding the diameter of the foam tube 2 while conveying it, and a second core 62a for holding the foam tube 2.
And a holding roller 62b.

The expanded core 62a has a structure similar to that shown in FIGS.
As shown in FIG. 5, the upstream side in the tube transport direction is tapered, and the downstream end has a tubular shape with an opening. The downstream side in the tube transport direction is bent, and the pipe 11 is bent on the outer bent surface of the bent portion 62c. An insertion hole 62d is formed for inserting into the expanded core 62a. The insertion hole 62d serves as a guide passage for inserting the pipe 11 into the foam tube 2.

In the pipe insertion device 62, the foam tube 2
Is expanded along the tapered surface formed on the upstream side in the conveying direction of the expanded core 62a, and the expanded tube 2 is expanded so that the cut 21 is located on the outer bent surface of the bent portion. 62a.

Therefore, when the foam tube 2 is bent at the bent portion 62c of the expanded core 62a, the cut 21 further expands, and the expanded tube 2 further expands in diameter. 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 to facilitate insertion of the pipe 11.

The second holding roller 62b has a shape in which the center of the roller surface in the axial longitudinal direction is tapered and is rotatably supported by a support plate 64. Then, the foam tube 2 to be conveyed is always positioned in the concave portion of the second holding roller 62b so that the foam tube 2 is expanded.
The foam tube 2 is held by the second holding roller 62b and the expanded core 62a so as not to deviate from 2a.

In the present embodiment, a bent portion 62c is formed in the expanded core 62a, and the foam tube 2 is bent so that the cut 21 of the foam tube 2 is located on the outer bending surface, so that the feeding device 51 is provided. While linearly transporting the pipe 11 fed out from the pipe 11, the transport path of the foam tube 2 is merged with the transport path of the pipe 11 at the bending portion forming position, and the diameter is expanded from the cut 21 widened at the bending portion 62c. The pipe 11 can be easily fitted into the pipe 11 by inserting the pipe 11 into the insertion hole 62d of the core 62a.

At this time, in order to reduce the friction between the outer surface of the expanded core 62a and the inner surface of the foam tube 2, the expanded core 6 is formed.
The outer surface of 2a is preferably subjected to a processing treatment such as a fluororesin coating to reduce the frictional resistance.

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 side of the bent portion 62c) of the foam tube 2. At the same time, a cooling air supply pipe 62f for supplying cooling air into the expanded core 62a is connected to the expanded core 62a. The cooling air supplied from the cooling air supply pipe 62f into the expanded core 62a is discharged from the cooling air discharge hole 62e to cool the foam tube 2 inserted in the expanded core 62a from the inner surface side. There is.

The expanded core 62a shown in FIGS. 6 and 7 is used.
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, a surface treatment such as a fluororesin coating process was applied to the surface of the expanded core 62a.
As 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 expanded core 62a, or a spiral groove or expanded core 62a is formed on the outer surface of the expanded core 62a.
The frictional resistance may be reduced by forming a plurality of vertical grooves extending in the lengthwise direction or by forming a recess for reducing the contact area of the expanded tube 2 with the expanded core 62a.

A case where a plurality of annular grooves 62g extending in the circumferential direction are formed on the outer surface of the expanded core 62a will be described with reference to FIGS. 8 to 11. 9 is a cross-sectional view of the expanded core 62a shown in FIG. 8 taken along line XX. The expanded core 62a shown in FIG.
Is inserted into the foam tube 2 in a straight state, and a taper 62h having a tapered shape is formed on the upstream side in the tube transport direction, and the downstream side in the tube transport direction is bent.

An annular groove (recess) 6 extending in the circumferential direction is formed on the outer peripheral surface of the expanded core 62a on the upstream side of the bent portion 62c in the tube conveying direction and on the downstream side of the taper 62h.
A plurality of 2 g are formed. Further, an insertion hole 62d for inserting the pipe 11 into the expanded 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 foam tube 2, and has a downstream end opened.

Then, the annular groove 6 in the expanded core 62a.
As shown in FIGS. 8 and 9, a plurality of cooling air discharge holes 62e are formed in 2g, and a cooling air supply passage 62i for supplying cooling air is formed inside the expanded core 62a. From the cooling air supply passage 62i to the expanded core 6
The cooling air supplied to the inside of 2a is cooled by the cooling air discharge hole 62.
The foam tube 2 discharged from e and inserted into the expanded core 62a is cooled from the inner surface side.

In the expanded core 62a shown in FIG. 8, the pipe 11 is inserted straight into the foam tube 2 while bending the foam tube 2.
The expanded core 62a may have a linear shape like the expanded core 62a shown in FIG. The diameter-expanding core 62a shown in FIG. 10 has a tapered taper 62h on the upstream side in the tube conveying direction, and an annular groove (recessed portion) extending in the circumferential direction on the outer peripheral surface of the diameter-expanding core 62a on the downstream side of the taper 62h. ) 62 g are formed, and an insertion hole 62 d for inserting the pipe 11 into the diameter-expanding core 62 a is opened at the middle portion in the lengthwise direction of the diameter-expanding core 62 a. It is opened at the downstream end.

Insertion hole 62 of expanded core 62a shown in FIG.
d bends the shape of the guide passage so as to bend the pipe 11 inside the insertion hole 62d, and prevents the pipe 11 from coming into contact with the opening end of the insertion hole 62d when the pipe 11 is inserted into the insertion hole 62d. The opening area on the insertion side of the pipe 11 is formed wide. 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 conveyed linearly.

Further, as shown in FIG. 11, the expanded core 62
The diameter-expanding core 62 shown in FIG.
The pipe 11 may be inserted into the foam tube 2 while bending the foam tube 2 and the pipe 11 more gently than the angle a.

The diameter-expanding core 62a shown in FIG. 11 also has a tapered taper 62h on the upstream side in the tube conveying direction, and an annular ring extending in the circumferential direction on the outer peripheral surface of the diameter-expanding core 62a on the downstream side of the taper 62h. A plurality of grooves (recesses) 62g are formed, and the pipe 1 is provided at the middle portion in the length direction of the expanded core 62a.
The insertion hole 62d for inserting 1 into the diameter-expanding core 62a is opened, and the insertion hole 62d is opened at the downstream end of the diameter-expanding core 62a.

Further, as for the insertion hole 62d of the expanded core 62a shown in FIG. 11, the shape of the guide passage is curved so that the pipe 11 is curved inside the insertion hole 62d, and when the pipe 11 is inserted into the insertion hole 62d. In order to prevent the pipe 11 from coming into contact with the opening end of the insertion hole 62d, the opening area on the insertion side of the pipe 11 is formed wide.

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
The downstream side in the feeding direction of the is formed by a conical tapered cylindrical body 63a, which has a tapered shape.
By sending the foam tube 2 together with the pipe 11 and allowing the foam tube 2 to pass through the tubular body 63a, the cut portion 21 of the foam tube 2 expanded by the diameter-expanding core 62a is closed and the foam tube 2 is removed. The diameter can be reduced.

At this time, in order to reduce friction between the outer surface of the foam tube 2 and the inner surface of the tubular body 63a, the tubular body 63a is formed.
It is preferable to perform a processing treatment such as a fluororesin coating on the inner surface of the to reduce frictional resistance.

Further, in the skin layer forming step section 34, the skin layer forming extruder 71 in which the non-foaming thermoplastic resin composition for forming the skin layer 13 is melt-kneaded, and the foam tube 2 are introduced. Further, the molten resin extruded from the skin layer forming extruder 71 is supplied, and the skin layer forming die 72 for forming the skin layer 13 on the outer periphery of the foam tube 2 and the skin layer forming die 72 come out. Third receiving a heat-insulated pipe 1
And a take-off machine 73.

The skin layer forming extruder 71 is equipped with a raw material hopper 71a to which the thermoplastic resin composition is supplied.
The skin layer forming extruder 71 is connected to a skin layer forming die 72.

Although not shown, the skin layer molding die 72 was provided with a passage for passing the foam tube 2 and a resin supply passage for supplying the molten resin from the skin layer molding extruder 71. It is a crosshead die. Further, it is preferable to provide an uneven thickness adjusting mechanism at the outlet portion. Furthermore, in order to make it difficult for the heat of the molten resin flowing through the resin supply path to be transferred to the foam tube 2 inside the skin layer molding die 72,
It is preferable to insert a member having a heat insulating property such as a resin cylinder into the inner surface of the passage.

When the foam tube 2 is introduced together with the pipe 11 into the passage of the skin layer molding die 72, the molten resin for forming the skin layer is supplied from the resin supply passage to the outer surface of the foam tube 2, and the foam tube is formed. The outer peripheral surface of No. 2 is covered with the skin layer 13.

According to the heat insulation pipe manufacturing apparatus in the first embodiment described above, first, in the foam tube manufacturing step section 31a, the molten resin composition in which the carbon dioxide gas as the foaming agent is dissolved is used as the foam tube molding extruder. After being extruded from 41, it is sent to a foaming mold 42 connected to a foaming tube molding extruder 41. While the foaming mold 42 is temperature-adjusted to the optimum foaming temperature, the foaming resin composition in the form of a tube is released from the foaming mold 42 to the atmospheric pressure, and a foaming tube having a uniform foaming state as shown in FIG. 2 is produced. The foam tube 2 coming out of the foam mold 42 is the first
It is sent to the foam layer forming step unit 33 by the take-off machine 43.

In the pipe feeding process section 32a, the pipe 11 is fed from the feeding device 51 by the second take-up machine 52, and the curl is corrected by the curl correction device 53.
It is sent to the foam layer forming step unit 33.

The foam tube 2 sent to the foam layer forming process section 33 by the first take-up machine 43 is used as the cut forming device 6.
The first cutter blade 61a makes continuous cuts 21 in the extrusion direction (longitudinal direction of the tube), resulting in the state shown in FIG.

The foam tube 2 is guided by the tapered surface formed on the upstream side of the expanded core 62a in the pipe insertion device 62 in the conveying direction, and the expanded tube 2 is press-fitted into the expanded core 62a to expand its diameter. Then, in the bent portion 62c of the expanded core 62a, the cut 21 of the foam tube 2 is further expanded, 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. To be done.

As described above, the foam tube 2 which has undergone the foam tube manufacturing step, the slit forming step and the foam tube expanding step, and the pipe 11 drawn out by the pipe feeding step.
Are joined together and the pipe 11 is inserted into the foam tube 2. First, the pipe 11 is connected to the second take-up machine 52.
And is inserted into the inside of the expanded core 62a through the notch.

When the pipe 11 passes through the expanded core 62a and is inserted into the expanded tube 2, the expanded tube contractor 63 contracts the expanded expanded tube 2. It At this time, the foam tube 2 is sent together with the pipe 11 into the tapered cylindrical body 63a and the foam tube 2 is passed through the cylindrical body 63a, so that the expanded tube 2 expanded by the expanded core 62a.
21 is easily closed and the diameter of the foam tube 2 is reduced, resulting in the state shown in FIG.

Next, the foam tube 2 whose diameter has been reduced with the pipe 11 inserted therein is used as the skin layer forming extruder 71.
It is introduced into the skin layer forming die 72 connected to the skin layer forming die 72, and the skin layer forming extrusion is performed while continuously passing the foam tube 2 in which the pipe 11 is inserted into the passage of the skin layer forming die 72. The molten resin for forming the skin layer is supplied from the machine 71. As a result, the outer peripheral surface of the foam tube 2 that covers the outer periphery of the pipe 11 in the skin layer forming die 72 is further covered with the skin layer 13, and the heat insulating pipe 1 shown in FIG. 5 is obtained.

The heat-insulating pipe 1 coming out of the skin layer forming die 72 is taken up by the third take-up machine 73 and taken up by a take-up machine (not shown). When the pipe is flexible, the heat-insulating pipe is wound by a winder, but when the pipe is not flexible, the heat-insulating pipe is cut into a certain length using a cutter.

As described above, 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 to be the foam layer 12 is manufactured, and then the foam layer 12 is foamed. Since the pipe 11 is inserted into the tube 2 so that the pipe 11 is covered with the foamed tube 2, the foamed layer 12 uniformly and highly foamed is obtained. Furthermore, since the series of steps for manufacturing the heat insulating pipe 1 can be performed in-line, the heat insulating pipe 1 can be manufactured efficiently and at low cost.

In the first embodiment, the tapered tubular body 63a is used as the foam tube diameter reducing device 63 in the foam tube diameter reducing step, but the foam tube diameter reducing step of reducing the diameter of the foam tube 2 into which the pipe 11 is inserted is used. Is not limited to the tapered cylindrical body 63a of the first embodiment described above, but includes a pair of pressing bodies that press the cut 21 of the expanded foam tube 2 in the butt direction, and the pressing body forms the foam tube. The diameter of the foam tube 2 may be reduced by sandwiching the two.

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 of FIG. 12, the central portion in the axial direction is recessed. There is one using a pair of rotatable rollers 63b having a tapered outer peripheral surface.

The heat insulating pipe manufacturing apparatus of the second embodiment for manufacturing the heat insulating pipe shown in FIG. 12 is the same as the foam tube reducing apparatus 63 in the foam tube reducing step in the manufacturing apparatus of the first embodiment. While changing the configuration,
A manufacturing method of the manufacturing apparatus according to the first embodiment is provided in which a break fusion step for melting the break 21 of the foam tube 2 is provided between the foam tube expanding step and the foam tube reducing step. Since they are the same, the same reference numerals are given to the same symbols and the description thereof will be omitted.

The foam tube diameter reducing device 63 of the second embodiment.
As shown in FIGS. 12 and 13, is composed of a pair of rotatable concave rollers 63b having a tapered outer peripheral surface with a concave center portion in the axial direction.

In the foam tube diameter-reducing device 63 of the second embodiment, the expanded foam tube 2 is introduced between two concave rollers 63b, and the cuts 21 of the foam tube 2 are brought into contact with each other by the concave rollers 63b. Foam tube 2 pressed in the direction and expanded by the expanded core 62a
The diameter of the foam tube 2 is reduced by closing the cut 21.

Further, on the upstream side of the concave roller 63b, as shown in FIGS. 12 and 13, the foam tube 2 is provided.
A cut fusing device 8 for fusing the cut 21 is provided, and the cut fusing device 8 is a hot air supply device (not shown).
And a hot air nozzle 81 serving as a heating unit. The break fusion device 8 melts the surface layer resin of the break 21 of the foam tube 2 into which the pipe 11 is inserted by the hot air discharged from the hot air nozzle 81, and the foam tube diameter reducing device 6
When the diameter is reduced by the two concave rollers 63b of No. 3, the cut 21 can be fused and the cross section of the fused portion can be brought into the state shown in FIG.

Although not shown, the hot air supply device is composed of a fan and a heater, the temperature of the hot air supplied to the hot air nozzle 81 can be controlled, and the temperature of the hot air supplied to the hot air nozzle 81 is controlled by the foam layer 12. By controlling the temperature to be equal to or higher than the melting point of the resin, the skin resin of the cut 21 can be melted.

The purpose of fusing the cuts 21 of the foamed tube 2 is to prevent the cuts 21 from opening in the skin layer forming process section 34. Whether the fusing is performed at regular intervals or continuously. Can be selected according to the purpose. By controlling the on / off of the fan of the hot air supply device, the surface layer resin of the cut 21 can be melted intermittently or continuously.

The cut surface fusion process performed by the cut fusion device 8 is not limited to the cut surface fusion of blowing hot air as described above, and the cut 21 directly formed on the hot plate composed of the heater and the metal plate.
May be brought into contact with each other to melt the surface layer resin of the cut 21.

As described above, in the second embodiment, since the foam tube diameter reducing device 63 uses the pair of rotatable rollers 63b having the tapered outer peripheral surface with the axial center recessed, the diameter is expanded. The diameter of the foam tube 2 can be easily reduced, and the melted cut 21 can be easily fused. Moreover, the foam tube 2 formed by the concave roller 63b
Since the diameter reducing operation can be performed without applying tension to the foam tube 2, it is possible to prevent only the foam tube 2 from contracting when the heat insulating pipe is cut and stabilize the product dimension. Can be achieved.

In the second embodiment, after the pipe inserting step and before the skin layer forming step, there is provided a cut fusion step of fusion-bonding the facing surfaces of the cut 21 of the foam tube 2 having the reduced diameter. Therefore, the cut 21 can be fused before the skin layer 13 is formed.
It is possible to surely prevent the cut 21 from opening during the formation of the, and it is possible to prevent the deterioration of quality.

Moreover, in the break fusion step, the surface resin of the break 21 of the foam tube 2 is melted by the hot air blown from the hot air nozzle 81 to fuse the facing surfaces of the break 21. It is possible to perform fusion bonding of the cut 21 portion without contacting the heat source directly and causing the foam tube 2 to lose its shape by a simple method.

Further, in the first embodiment, the foam tube supply step is constituted by the foam tube manufacturing step section 31a, and the foam tube diameter reducing step is performed by the foam tube diameter reducing device 6
Although the tapered tubular body 63a is used as 3, the foam tube 2 is prepared in a separate step in advance and wound around the reel 47 as in the third embodiment shown in FIG. 15, and the foam tube 2 is delivered from the reel 47. Foam tube feeding process unit 3 that sends the foam layer forming process unit 33 by the first take-up machine 43.
1b is provided, and in the same manner as in the second embodiment described above, a break fusion process using a hot air nozzle 81,
You may make it provide the foaming tube diameter reduction process by the foaming tube diameter reduction apparatus 63 which consists of two concave rollers 63b.

Further, in the first embodiment, in order to fit the foamed tube 2 to the pipe 11, the pipe feeding process section 32a is provided, and the pre-manufactured pipe 11 is fed from the feeding machine 51 to perform the pipe inserting process. However, as in the fourth embodiment shown in FIG. 16, a pipe molding extruder 54 in which the thermoplastic resin composition for forming the pipe 11 is melt-kneaded, and a pipe molding extruder 54. A pipe manufacturing process section 3 provided with a mold 55 for molding the pipe 11 into which the molten resin extruded from the mold is injected, and a second take-up machine 52 for receiving the pipe 11 coming out of the mold 55.
2b is provided, and similarly to the above-described second embodiment, a break fusion step by the hot air nozzle 81 and a foam tube diameter reducing step by the foam tube diameter reducing device 63 including two concave rollers 63b are provided. Good.

[0133]

EXAMPLES The present invention will be specifically described below with reference to examples, but the examples are merely examples and do not limit the present invention. (Example 1) Example 1 is the same as the above-described second embodiment (Fig. 1).
The manufacturing apparatus in 2) was used. Low-density polyethylene (manufactured by Nippon Polychem; product number "LF440HB") 100
Parts by weight and talc (manufactured by Sumika Color Co., Ltd., product number “SS-11-
20 ") 3 parts by weight was supplied to the raw material hopper 41a of the foaming tube molding extruder 41, and heated and melted in the foaming tube molding extruder 41. On the other hand, carbon dioxide gas was supplied as a foaming agent from the cylinder 44 to the foaming agent supply section 41b of the foaming tube molding extruder 41.

At this time, after the carbon dioxide gas discharged from the cylinder 44 is cooled by the cooling device 45, the metering pump 46 is used to
Resin extruding amount of the foaming tube molding extruder 41 is 10 kg /
It was supplied while being controlled to be 0.2 kg / h with respect to h, and kneaded at 120 ° C. in the foaming tube molding extruder 41. The temperature of the foaming mold 42 was set to 108 ° C., and an outlet having an inner diameter of 3 mm and an outer diameter of 6 mm was released to atmospheric pressure to obtain a uniform foamed tube 2 having an inner diameter of 18 mm, an outer diameter of 24 mm and a foaming ratio of about 6 times.

Then, the foam tube 2 is taken by the first take-up machine 43 and sent to the cut forming device 61 through the guide roller 47, and the cut tube 21 is continuously cut in the extruding direction by the long cutter blade 61a. I put it in. Subsequently, the expanded tube 2 was guided to the expanded core 62a, the opening was introduced into the expanded core 62a, and the cut 21 of the expanded tube 2 was widened at the bent portion 62c.

On the other hand, as the pipe 11, a cross-linked polyethylene pipe having an outer diameter of 17 mm is fed from the feeding device 51 by the second take-up device 52 at a speed of 3 m / min, inserted into the expanded core 62a, and covered with the foam tube 2. Pipe 11
Got Subsequently, a pair of rotatable concave rollers 63b each having a tapered central portion in the axial direction are pressed in the abutting direction by a cut of the foam tube 2 whose diameter is expanded, so that the expanded core 62a is expanded. Break 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 break was not performed.

On the other hand, 100 parts by weight of low-density polyethylene (manufactured by Nippon Polychem, product number "LF440HB") and pigment masterbatch (manufactured by Toyo Ink, product number "TET3MA1".
070RG ") 5 parts by weight of a mixture with the raw material hopper 71.
It was supplied to the skin layer forming extruder 71 from a and melt-kneaded at 170 ° C. Then, 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 die 72, and the skin layer 13 having a thickness of 200 μm is further provided on the outer periphery of the pipe 11 covered with the foam tube 2. The heat-insulated pipe 1 covered with the thickness was taken up by the third take-up machine 73 and taken up by the take-up machine.

(Example 2) Before introducing the covered pipe 11 covered with the foam tube 2 into the foam tube diameter-reducing device 63, a break fusion step is provided to raise the heater temperature of the hot air supply device to 200 ° C. After setting and melting the surface layer resin of the cut 21 continuously through the hot air nozzle 81, it was introduced into the foam tube diameter-reducing device 63 and the cut 21 was continuously fused. Insulated pipes were manufactured. 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.

(Embodiment 3) The fan of the hot air supply device is set to 10
After turning on / off every second to intermittently melt the cut 21, the cut tube 21 is introduced into the foam tube diameter reducing device 63.
An adiabatic pipe was produced in the same manner as in Example 2 except for intermittently fusing. In Example 3, the cuts 21 were intermittently fused, but it was possible to reliably prevent the cuts 21 from separating when the skin layer 13 was formed.

Example 4 In Example 4, the manufacturing apparatus in the third embodiment (FIG. 15) described above was used. The foam tube 2 is wound up in advance on a reel or the like, and as shown in FIG.
A heat-insulating pipe was manufactured in the same manner as in Example 1 except that the above was sent to the foam layer forming step section 33. Since the foamed tube 2 is manufactured in advance and wound on a reel or the like, the heat generated during the formation of the cut 21 can be reduced as compared with the case where the foamed tube 2 is manufactured in-line, and the cut is formed. I was able to increase the line speed of time.

(Example 5) In Example 5, the manufacturing apparatus in the fourth embodiment (FIG. 16) described above was used. As shown in FIG. 16, a polyethylene pipe having an outer diameter of 17 mm is manufactured by an extrusion line arranged in parallel without feeding a preformed pipe, and a foam layer forming step is continuously performed by the second take-up machine 52. A heat insulating pipe was manufactured in the same manner as in Example 1 except that the heat insulating pipe was sent to the part 33. Since the pipe 11 and the foam tube 2 can be formed in-line, the manufacturing cost can be reduced.

Comparative Example A heat insulating pipe was manufactured by the method for manufacturing a heat insulating pipe in Example 1 disclosed in JP-A-61-293825. In the comparative example, a cross-linked high-density polyethylene pipe having an outer diameter of 17 mm was used as the pipe.

As the resin composition for forming the foam layer, 100 parts by weight of low-density polyethylene and P as a foaming agent were used.
A mixture of 1.5 parts by weight of -P'-oxybis- (benzenesulfonylhydrazide) was used. As the resin composition for forming the skin layer, high density polyethylene 1
A mixture of 00 parts by weight and 2.0 parts by weight of carbon black was used.

Then, using a long land die, while passing a pipe through the long land die, while simultaneously supplying the foam layer-forming resin composition and the skin layer-forming resin composition to the head by an extruder. The head and the long land die were passed through the pipe to simultaneously form a foam layer and a skin layer on the outer periphery of the pipe.

The foam layer of the heat insulating pipe obtained in the comparative example had a thickness of 3 mm and the skin layer had a thickness of 0.2 mm. As a result, only a heat insulating pipe having a foaming ratio of about 2 was obtained.

Further, the expanded core 6 shown in FIG. 6 and FIG.
Comparison was made between the contracted state of the foam tube 2 when 2a was used and when the expanded core 62a shown in FIG. 8 was used. When the expanded core 62a shown in FIGS. 6 and 7 is used, the length of the foamed tube (1000
mm), the contraction dimension at the cut end when the heat insulating pipe was cut after forming the heat insulating pipe was 15 mm, whereas when the expanded core 62a shown in FIG. 8 was used,
The length of the foam tube (100
0 mm), the shrinkage dimension at the cut end when the heat-insulating pipe after the formation of the heat-insulating pipe was cut was 1 mm.

From the above results, as shown in FIG. 8, the expanded core 62a is provided with the recess 62g for reducing the contact area with the inner surface of the foam tube 2, so that the expansion of the foam tube 2 due to frictional heat is reduced. Thus, the shrinkage of the foam tube 2 after forming the heat insulating pipe could be suppressed.

[0148]

As described above, according to the heat insulating pipe of the present invention, the foam layer is formed in a tubular shape, and the tubular foam layer has a longitudinal direction for inserting the pipe into the cylinder. Since a continuous skin layer is formed on the outer periphery of the foam layer having a cut, a foam layer having a high degree of foaming is uniformly obtained, while insulating pipes such as connecting pipes between heat insulating pipes are obtained. If the foam layer has to be removed from the pipe at the axial end of the, the foam layer can be easily peeled from the cut portion, so that the work of connecting the heat insulating pipe is also facilitated.

Further, according to the manufacturing method and the manufacturing apparatus of the present invention, the outer circumference of the pipe can be uniformly covered with a foam layer having a high degree of foaming, and the outer circumference thereof is covered with a skin layer. Can be manufactured efficiently and at low cost.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a manufacturing apparatus for manufacturing a heat insulating 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 heat insulating pipe of the present invention.

FIG. 3 is a cross-sectional view of the foam tube in which a slit is formed in the slit forming step in the method for manufacturing a heat insulating pipe of the present invention.

FIG. 4 is a cross-sectional view of a pipe in which a foam layer is formed on the outer periphery of the pipe through a diameter reducing process after the pipe is inserted into the foam tube in the pipe inserting process in the method for manufacturing a heat insulating pipe of the present invention. is there.

FIG. 5 is a cross-sectional view of a heat insulating pipe manufactured by the heat insulating pipe manufacturing method of the present invention.

FIG. 6 is a perspective view showing a diametrical expansion core of a cut forming device and a pipe insertion device in a manufacturing apparatus for manufacturing a heat insulating pipe.

FIG. 7 is a perspective view showing another embodiment of the break forming device in the manufacturing apparatus for manufacturing the heat insulating pipe and the expanded core of the 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 the heat insulating pipe.

9 is a sectional view taken along line XX in FIG.

FIG. 10 is a perspective view showing another embodiment (straight diameter expanding core) of the expanding core of the pipe inserting device in the manufacturing apparatus for manufacturing the heat insulating pipe.

FIG. 11 is a perspective view showing another embodiment of a diameter-expanding core of a pipe insertion device in a manufacturing apparatus for manufacturing an adiabatic pipe (a foam tube and a pipe are fitted with a bending-type diameter-expanding core while curving). Is.

FIG. 12 is an overall configuration diagram of a manufacturing apparatus for manufacturing a heat insulating 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 view showing a method of manufacturing a heat-insulated pipe according to the present invention, in which a cut is melted in a state where a foam layer is formed on the outer periphery of the pipe through a diameter reduction step after the pipe is inserted into the foam tube in the pipe insertion step It is a pipe sectional view of the state where it was put on.

FIG. 15 is an overall configuration diagram of a manufacturing apparatus for manufacturing a heat insulating pipe according to a third embodiment of the present invention.

FIG. 16 is an overall configuration diagram of a manufacturing apparatus for manufacturing a heat insulating pipe according to a fourth embodiment of the present invention.

[Explanation of symbols]

1 Insulated pipe 11 pipes 12 Foam layer 13 epidermis 2 foam tube 21 breaks 31a Foam tube manufacturing process department 41 Foam Tube Extruder 42 foam mold 61a, 61i Cutter blade 62a Expanded core 63a tubular body 71 Extruder for forming skin layer 72 Mold for forming skin layer

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[Procedure amendment]

[Submission date] July 19, 2002 (2002.7.1)
9)

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] Full text

[Correction method] Change

[Correction content]

[Document name] Statement

Title: Photocurable conductive coating composition

[Claims]

Detailed Description of the Invention

[0001]

The present invention relates, the foam layer is formed on the pipe surface, further to a process for the preparation of coated pipes and the coating pipe the skin layer is formed on the outer periphery of the foam layer.

[0002]

Heretofore, pipes, for example, synthetic resin pipe, copper pipe, for the purpose of imparting heat insulating property and the like such as a steel tube,
A coated pipe in which the outer periphery of the pipe is coated with a foam layer formed of a foamed synthetic resin composition is used.

However, since the foam layer has low frictional strength and scratching strength, if the foam layer is exposed to the outside, there is a problem that it is easily damaged by friction or scratching during construction or after piping.

Therefore, for the purpose of protecting the surface of the foam layer, it has been proposed that a skin layer formed of a non-foaming synthetic resin is further formed on the outer peripheral surface of the foam layer.

For example, Japanese Patent Application Laid-Open No. 61-293825 discloses a method for producing an adiabatic pipe using an extruder, in which a foam layer is formed on the surface of the pipe and a skin layer is formed on the outer periphery of the foam layer. It is disclosed. In this manufacturing method, a long land die is used for the die of the extruder, and the foam layer-forming composition and the skin layer-forming resin are supplied to the head of the extruder 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.

[0006]

However, JP-A-61-161
In the manufacturing method disclosed in Japanese Patent No. 293825, since foaming is performed in the long land die and cooling is performed in the long land die, foaming of the foam layer is performed between the outer surface of the pipe and the long land die. The shape is fixed by being cooled in the long land die while being restricted by the inner surface and foaming being restricted.

Therefore, when a thermal decomposition type chemical foaming agent is used, it is cooled before it is completely decomposed by heat, so that the gas pressure of the foaming agent dissolved in the resin is lowered and the expansion ratio is increased. Was only about double.
Further, even when using a physical foaming agent, the resin composition of the foam layer is foamed in a state where foaming in the thickness direction is restricted by the long land die and the pipe, and when it comes out from the long land die, Since the foam layer had been covered with the skin layer that had been cooled and fixed, a high expansion ratio could not be obtained.

Further, since the conventional heat-insulating pipe is formed by extruding the foam layer and the skin layer on the outer periphery of the pipe at the same time, the foam layer is brought into close contact with the entire outer peripheral surface of the pipe, and a plurality of layers are formed. When connecting the heat-insulating pipe, it is necessary to peel off the foam layer at the end of the heat-insulating pipe, but there is also a problem that the peeling work is difficult because the foam layer adheres too much to the outer peripheral surface of the pipe.

The present invention, to be and a foam layer and a skin layer
It has been made to solve the problems in the method of manufacturing the covering pipe, the outer circumference of the pipe, uniformly while can form a high-foamed foam layer, provide a coating pipe peeling operation also allows easier of the foam layer from the pipe At the same time, it is an object of the present invention to provide a method for efficiently and inexpensively manufacturing a covered pipe in which a highly foamed foam layer can be uniformly formed on the outer circumference of the pipe, and the outer circumference of which is covered with a skin layer.

[0010]

To achieve the above object, according to an aspect of, the invention according to claim 1, the foam layer is formed on the pipe surface, further coating the skin layer is formed on the outer periphery of the foam layer In the pipe, the foam layer is formed in a tubular shape, the tubular foam layer is formed with a cut extending in the longitudinal direction for inserting the pipe into the cylinder, and a foam layer having a cut is formed. It is characterized in that a continuous skin layer is formed on the outer periphery.

As the pipe used in the present invention, for example,
For example, a pipe having a heat insulating property, for example, a metal pipe such as a steel pipe or a copper pipe, a polyolefin pipe such as polyethylene, polypropylene, or polybutene-1, or a synthetic resin pipe such as a crosslinked polyolefin pipe such as crosslinked polyethylene can be used. .

The foam layer coated on the outer periphery of the pipe is made of a foamed resin composition containing a thermoplastic resin which can be foamed in a low pressure zone by a foaming agent. Examples of the thermoplastic resin include polyethylene, polypropylene, Extrudable thermoplastics such as polystyrene, vinyl chloride, vinylidene chloride, ethylene-vinyl acetate copolymer, chlorinated polyethylene, ethylene-propylene copolymer, ethylene-ethyl acrylate copolymer, polyethylene terephthalate, ABS resin, acrylic resin Examples thereof include resins, and these may be used alone or in combination of two or more kinds.
The skin layer coated on the outer periphery of the foam layer is preferably an extrudable resin and is a thermoplastic resin having scratch resistance.

According to the first aspect 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 cylinder. Since a continuous skin layer is formed on the outer periphery of the foam layer having a cut, a uniform highly foamed foam layer can be obtained, and the axial end portion of the coated pipe, such as the connection work between the coated pipes, can be performed. When the foam layer has to be removed from the pipe in (1), the foam layer can be easily peeled from the cut portion, so that the work of connecting the covered pipe is facilitated.

The invention described in claim 2 is the same as claim 1
In the invention of the coated pipe as described in the above item 1, the breaks of the tubular foam layer are intermittently fused. Intermittent fusing of the breaks means that there are fused parts and unfused parts along the breaks.

According to the second aspect of the present invention, since the cuts of the tubular foam layer are intermittently fused, the cuts at the time of forming the skin layer at the fused portion. While preventing the opening, the foam layer can be easily peeled from the pipe in the unfused portion of the break.

A third aspect of the present invention is a method for producing a covered pipe in which a foam layer is formed on the surface of the pipe, and a skin layer is formed on the outer periphery of the foam layer, which is the foam layer. A slit forming process in which a foam tube is continuously supplied while making continuous cuts in the foam tube in the longitudinal direction of the foam tube, and a pipe that inserts a pipe into the foam tube from the break while expanding the diameter of the cut foam tube. The insertion pipe, the foamed tube diameter reducing process for reducing the diameter of the foamed tube in which the pipe is inserted, and the skin layer forming process for forming a skin layer on the outer periphery of the foamed tube in which the pipe is inserted and reduced in diameter form a covered pipe. It is characterized by being manufactured.

As a means for supplying the foam tube, a foam tube which is a foam layer produced in advance may be wound on a reel or the like and supplied to the slit forming step, or the foam tube manufacturing step. May be provided so that the manufactured foam tube is directly supplied to the slit forming step.

According to the third aspect of the present invention, 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 produced, and then the foam tube is formed. Since the pipe is covered with the foam tube by forming a cut in the foam tube and inserting the pipe into the foam tube, a foam layer having a high degree of uniform foam can be obtained.

According to a fourth aspect of the present invention, in the method for producing a covered pipe according to the third aspect, the slit forming step is a foaming process in which the foaming tube is independently extruded for continuously supplying the foaming tube. It is characterized by having a tube manufacturing process section. The foam layer coated on the outer circumference of the pipe is made of a foamed resin composition containing a thermoplastic resin that can be foamed in the low-pressure zone by a foaming agent, as described above. When 2 to 3 parts by weight of the cell nucleating agent is added, the cells of the obtained foam become fine and the coating performance is improved.

The foaming agent for foaming the thermoplastic resin is not particularly limited as long as it does not deteriorate the thermoplastic resin, and for example, a thermal decomposition type foaming agent such as azodicarbonamide, benzenesulfonyl hydrazide, toluenesulfonyl hydrazide, or the like. Mention may be made of physical blowing agents which are gases or volatile liquids under pressure. According to the invention described in claim 4, it is possible to perform the series of steps for producing the coated pipes in-line, the coated pipe efficiently, can be manufactured at low cost.

According to a fifth aspect of the present invention, in the method for producing a covered pipe according to the fourth aspect, the foam tube manufacturing step section extrudes a molten resin mixed with a physical foaming agent from an extruder for molding a foam tube. And is sent to a foaming mold connected to an extruder for forming a foaming tube, and the foaming mold is released to atmospheric pressure to manufacture a foaming tube.

The physical foaming agent includes nitrogen, carbon dioxide, air and the like as gas, and the low boiling point aliphatic hydrocarbons such as propane, butane and pentane, alcohols, ketones and esters as easily volatile liquids. Examples thereof include low boiling point organic compounds such as compounds, halogenated hydrocarbons such as monochlorodifluoromethane, dichlorodifluoromethane, and dichlorotetrafluoroethane. These may be used alone or in combination of two or more kinds. . According to the fifth aspect of the present invention, the foam tube is exposed to the atmosphere by the physical foaming agent and foam-molded, so that the foaming can be uniformly performed while the predetermined expansion ratio is obtained.

The invention according to claim 6 is characterized in that, in the method for producing a covered pipe according to claim 5, the physical foaming agent supplied to the molten resin in the foaming tube molding extruder is carbon dioxide gas. To do. When using an easily volatile liquid as a physical foaming agent, there is a possibility that the ozone layer may be destroyed or it is flammable, so many facilities require explosion-proof specifications, but carbon dioxide gas is used as a physical foaming agent. As a result, there is no possibility of depleting the ozone layer, the load on the environment can be reduced, and because it is nonflammable, explosion-proof specifications are not required as equipment, and the equipment becomes simple. Further, it has high solubility in resin.

The invention according to claim 7 is the method for producing a covered pipe according to any one of claims 4 to 6, wherein the expansion ratio of the foamed tube extruded and foamed in the foamed tube manufacturing step is 5 It is characterized by being more than double.

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 preferred expansion ratio of the foam layer is 5 times or more is up to 5 times. the magnification is higher rapidly reduced thermal conductivity, because the heat insulating performance and the like are improved. In the resin composition forming the foam layer or the skin layer, if necessary, a stabilizer, an antioxidant, a processing aid, a lubricant, a foaming aid,
Fillers, pigments, flame retardants and the like can be added.

The invention according to claim 8 is the method for producing a covered pipe according to any one of claims 3 to 7, wherein the slit forming step includes cooling the foam tube and / or a cutter blade for forming a cut. It has a cooling step for performing. According to the invention of claim 8, in the slit forming step, since the foam tube and / or the cutter blade for forming the slit is cooled, the foam tube has residual heat due to extrusion molding, and the cutter blade has friction heat. It is possible to suppress the temperature rise of the cut portion at the time of forming the cut portion due to the occurrence of cracks, and prevent the cut formation failure due to the temperature rise of the cut portion.

According to a ninth aspect of the present invention, in the method for manufacturing a covered pipe according to any of the third to eighth aspects, in the pipe inserting step, a taper is formed on the upstream side in the feed direction of the foam tube. Introducing a notched foam tube into the diameter-expanding core having, and expanding the diameter while conveying the foam tube, and inserting the pipe from the notched slit in the foam tube to be conveyed. It is a thing. According to the invention of claim 9,
The expanded core makes it easy to widen the cuts in the foam tube, making it easier to insert the pipe into the foam tube.

According to a tenth aspect of the present invention, in the method of manufacturing a covered pipe according to any of the third to ninth aspects, the pipe inserting step includes a cooling step of cooling the foamed tube to be expanded in diameter. It is characterized by doing.

While continuously feeding the foam tube,
When the pipe is inserted into the foam tube, the temperature of the inner and outer surfaces of the foam tube may rise and the foam tube may expand if the amount of the foam tube fed out increases. Then, it will be the elongation is generated in the foaming tube foam tube after skin layer formation shrinkage occurs, and phenomena of the pipe end portion of the pipe after production of the coated pie <br/> flop will be largely exposed, coated on the way Even when the pipe is cut, the phenomenon that the pipe is largely exposed at the cutting portion occurs.

According to the tenth aspect of the present invention, the foamed tube can be cooled in the cooling step in the pipe inserting step even if the amount of the foamed tube fed out increases, so that the temperature rise of the foamed tube is suppressed and the foamed tube is suppressed. Can be prevented, and the pipe can be prevented from being exposed from the end of the coated pipe.

According to an eleventh aspect of the present invention, in the method for manufacturing a covered pipe according to any of the third to tenth aspects, in the step of reducing the diameter of the foam tube, the downstream side of the foam tube in the feed direction is tapered. The foamed tube in which the pipe is inserted is fed into the inside of the tubular body, and the cut portion of the foamed tube is joined to reduce the diameter of the foamed tube. According to the invention as set forth in claim 11, the diameter of the foamed tube expanded by the tubular body can be easily reduced.

According to a twelfth aspect of the present invention, in the method for manufacturing a covered pipe according to any one of the third to tenth aspects, the step of reducing the diameter of the foamed tube has a tapered outer periphery with a recessed central portion in the axial direction. Using a pair of rotatable rollers having a surface, introduce a foam tube expanded in diameter between two rollers, and press in the direction in which the facing surfaces of the cuts of the foam tube are brought into contact with each other by the roller pair. It is characterized by reducing the diameter.

According to the twelfth aspect of the invention, the rotatable 1 having the tapered outer peripheral surface with the axial center recessed
By using a pair of rollers, it is possible to easily reduce the diameter of the expanded foam tube. Furthermore, since the diameter of the foam tube can be reduced without applying tension to the foam tube, it is possible to prevent the foam tube from shrinking when the coated pipe is cut, and stabilize the product dimensions. Can be achieved.

According to a thirteenth aspect of the present invention, in the method for producing a covered pipe according to any of the third to twelfth aspects, the diameter is reduced after the pipe inserting step and before the skin layer forming step. It is characterized in that it has a break fusion step of fusing the opposing surfaces of the break of the foamed tube. As a method for fusing the opposing surfaces of the cuts of the foamed tube, there are a method of continuously fusing the cuts in the length direction and a method of intermittently fusing along the breaks.

According to the thirteenth aspect of the present invention, since the cuts are fused before the skin layer is formed, it is possible to reliably prevent the cut portion from opening during the formation of the skin layer, and to improve the quality. It can prevent the deterioration.

According to a fourteenth aspect of the present invention, in the method for producing a covered pipe according to the thirteenth aspect, in the break fusion step, the surface layer resin in the break portion of the foam tube is melted by hot air to face the cut surface. It is characterized in that they are fused together. According to the invention as set forth in claim 14, the cut portion can be fused by a simple method without directly contacting the heat source and causing the foam tube to lose its shape.

The invention described in claim 15 is the method for manufacturing a covered pipe according to any one of claims 3 to 14, wherein in the step of forming the skin layer, the diameter of the foamed tube is reduced by inserting the pipe. It is characterized in that, while being fed into the skin layer forming die, the melted skin layer forming resin is extruded from the skin layer forming extruder into the skin layer forming die to form a skin layer on the outer periphery of the foam tube. It is a thing.

If the thickness of the skin layer is too thin, the surface of the foam layer cannot be completely protected due to friction or scratching.
The thickness is preferably 00 μm or more, and more preferably 200 μm or more. In addition, since it is highly likely that the unevenness of the foam surface is transferred to the skin layer, a pigment having a concealing property is added to the resin in order to improve the appearance, or embossing or embossing is performed. Is preferred. According to the fifteenth aspect of the present invention, the skin layer can be easily formed on the outer periphery of the foam tube in which the pipe is inserted and the diameter of which is reduced.

The invention according to claim 16 is a manufacturing apparatus of a covered pipe, wherein a foam layer is formed on the surface of the pipe, and further, a skin layer is formed on the outer periphery of the foam layer, which is the foam layer. Insert the pipe into the foam tube through the slit while expanding the diameter of the slit forming process part and the slit forming process part that continuously cuts the foam tube in the longitudinal direction of the foam tube while continuously supplying the foam tube A pipe insertion step part, a foam tube diameter reducing step part for reducing the diameter of the foam tube in which the pipe is inserted, and a skin layer forming step part for forming a skin layer on the outer circumference of the foam tube in which the pipe is inserted and reduced in diameter. It is characterized by having.

According to the coated pipe manufacturing apparatus of the sixteenth aspect, the foam layer for coating the surface of the pipe is not directly formed on the outer surface of the pipe, but is formed on the foam tube after manufacturing to be the foam layer. by forming a cut for inserting a pipe into the foam tube, by coating the pipes with foam tube, it is possible to produce a coating path <br/> type of skin layer is formed on the outer periphery of the foam tube, A coated pipe having a uniformly highly foamed foam layer is obtained.

According to a seventeenth aspect of the present invention, in the coated pipe manufacturing apparatus according to the sixteenth aspect, the pipe insertion step portion has a taper on the upstream side in the feed direction of the foam tube, and has a break. Equipped with a diameter-expanding core that expands the diameter of the foam tube inside.The diameter-expansion core has a recess on the outer surface that is not in contact with the foam tube, and inserts a pipe into the foam tube through the cut of the foam tube expanded by diameter expansion. It is characterized in that it is provided with a guide passage for making it.

The concave portion provided in the diameter-expanding core is formed by forming a plurality of annular concave grooves extending in the circumferential direction on the surface of the diameter-expanding core, forming a spiral groove on the surface of the diameter-expanding core, or feeding the foam tube. It can be obtained by forming a plurality of recessed grooves extending to.

According to the seventeenth aspect of the invention, the diameter of the foam tube is expanded while the inner surface of the foam tube is aligned with the taper outer peripheral surface of the expanded core, and the pipe is expanded from the guide passage of the expanded core. It can be easily inserted into the tube. Moreover, since the recessed 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, friction can be reduced. It is possible to reduce the temperature rise of the foam tube due to friction while smoothly expanding the diameter with the diameter-expanding core.

The invention as set forth in claim 18 is the apparatus for manufacturing a covered pipe as set forth in claim 16 or claim 17, wherein the pipe insertion step portion is provided with a cooling mechanism for cooling the expanded foam tube. It was configured. According to the invention as set forth in claim 18, 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 suppressed. Can be prevented, and the pipe can be prevented from being exposed from the pipe end portion of the coated pipe after manufacturing.

[0045]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. 1, a first embodiment of a manufacturing apparatus for manufacturing a coated pipe by the method for producing a coated pipe of the present invention is intended to schematically show, this coating Pas <br/> type production apparatus, The coated pipe 1 shown in FIG. 5 can be manufactured. The coated pipe 1 is, as shown in FIG.
A foam layer 12 serving as a heat insulating layer is formed on the surface of the pipe 11, and a skin layer 13 is further formed on the surface of the foam layer 12.

The coated pipe manufacturing apparatus of the first embodiment is
The foam tube 2 that will become the foam layer 12 shown in FIG.
As shown in, the cut 21 is continuous in the longitudinal direction of the tube.
And a slit forming process section (slit forming process)
While expanding the diameter of the foam tube 2 having the cut 21, the pipe inserting step (pipe inserting step) for inserting the pipe 11 from the cut 21 into the foam tube 2 and the diameter of the foam tube 2 in which the pipe 11 is inserted are reduced. Foam tube reducing step (foam tube reducing step)
And the foam tube 2 with the diameter reduced by inserting the pipe 11.
Through the respective manufacturing steps of the skin layer forming step (skin layer forming step) in which the skin layer 13 is formed on the outer periphery of the
The coated pipe 1 is manufactured. The slit forming process section also has a foam tube supply process for continuously supplying the foam tube 2.

The coated pipe manufacturing apparatus of the first embodiment is
As shown in FIG. 1, the foamed tube supply step is configured by a foamed tube manufacturing step section 31a for independently extruding and molding the foamed tube 2. In addition, between the pipe insertion step and the foam tube diameter reduction step, a heating portion 81 shown by a virtual line in FIG. 1 is provided to intermittently connect the opposing surfaces of the cut 21 of the foam tube 2 into which the pipe is inserted, Alternatively, there may be provided a break fusion step of continuously fusion bonding.

In this case, it is preferable that the heating section is constituted by a hot air nozzle 81 for blowing hot air onto the foam tube 2. Since the specific configuration and operational effects are the same as those of the heating unit shown in the second embodiment described later, the second configuration
This will be described in the embodiment.

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 foam tube manufacturing step section 31a for independently extruding and molding the foam tube 2 to be the foam layer 12, and flexibility. Pipe feeding process part 32a for feeding out the pipe 11, a foam layer forming process part 33 for performing a slit forming process, a pipe inserting process and a foam tube reducing process, and a skin layer forming process part 3 for performing a skin layer forming process.
4 and.

The foamed tube manufacturing process section 31a comprises a foamed tube molding extruder 41 in which a foamable thermoplastic resin composition for forming the foamed layer 12 is melt-kneaded, and a foamed tube molding extruder 41. The foamed metal mold 42 for molding the foamed tube 2 into which the melted resin is injected.
And a first take-off machine 43 for receiving the foam tube 2 coming out of the foam mold 42.

The extruder 41 for forming a foam tube is provided with a raw material hopper 41a to which the thermoplastic resin composition is supplied and a foaming agent supply section 41b, and a resin for forming the foam layer 12 from the raw material hopper 41a. While supplying the composition, the physical foaming agent in the cylinder 44 is supplied into the foaming tube molding extruder 41 from the foaming agent supply section 41b.

A cooling device 45 and a metering pump 46 are provided in the supply path between the cylinder 44 and the foaming agent supply section 41b. Since carbon dioxide is used as the physical foaming agent in this embodiment, In order to improve the supply efficiency, a cooling device 45 is provided in front of the metering pump 46, and carbon dioxide gas is liquefied in the cooling device 45 and supplied to the metering pump 46.

Further, in the metering pump 46, the supply amount of the foaming agent into the foaming tube molding extruder 41 is set so that a desired foaming ratio can be obtained with respect to the resin extrusion amount of the foaming tube molding extruder 41. Have control over.

The expansion ratio can be controlled by the amount of the foaming agent dissolved in the molten resin. When carbon dioxide gas is used as the physical foaming agent, in order to obtain an expansion ratio of 5 times or more, 1% by weight or more of carbonic acid in the molten resin is used. It is necessary to dissolve the gas.

However, if carbon dioxide gas is supplied in excess of the target magnification, bubble breakage will occur at the outlet of the foaming mold 42, and gas escape will be promoted. As a result, the magnification will not increase and bubble breakage will occur. It is necessary to control the amount of foaming agent supplied so that it does not exist.

In the foam tube molding extruder 41, the foaming agent is melted in the molten resin from the foaming agent supply section 41b while heating and melting the resin composition supplied from the raw material hopper 41a to form the foam tube. The molten resin is extruded into the foaming mold 42 connected to the extrusion extruder 41.

Further, in the foaming tube molding extruder 41, the foaming tube supplying extruder 41b is provided in the foaming tube molding extruder 41 so that the foaming agent can be stably supplied into the foaming tube molding extruder 41. The groove depth of the screw is formed so as to be deep at a portion facing the position where the foaming agent supply section 41b is formed, and the pressure of the molten resin is once reduced when the foaming agent is supplied.
In addition, 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 dullage.

Although not shown, the foaming mold 42 is composed of an inner core and an outer mold for molding in a tube shape, the inner core is held by a bridge, and the outer mold is a band heater or oil. The temperature can be adjusted by the medium.

The first take-up machine 43 is composed of a pair of first conveyor belts 43a which are rotationally driven. The first conveyor belt 43a sandwiches the foam tube 2 and the first conveyor belt 43a is rotationally driven. The foam tube 2 is sent to the foam layer forming process unit 33.

Therefore, in the foaming mold 42, the temperature of the resin composition supplied from the foaming tube molding extruder 41 is adjusted to the optimum foaming temperature, and the resin composition in the tube state from the foaming mold 42 is at atmospheric pressure. When released inside, the resin composition is foamed, and a uniform highly foamed foam tube 2 as shown in FIG. 2 is manufactured.

The optimum foaming temperature varies depending on the amount of the foaming agent dissolved in the molten resin in the plasticizing effect of the resin. Therefore, when the resin is crystalline, the melting point is ± 10 ° C., and when the resin is amorphous, Is preferably set within the range of the glass transition temperature ± 10 ° C. Further, it is preferable that the foaming mold 42 is provided with an uneven thickness adjusting mechanism.

A pipe feeding process unit 32 for feeding the pipe 11
As shown in FIG. 1, a is a payout machine 51 to which a pipe 11 which is manufactured and wound in advance by another extruder is attached.
And a second take-up machine 52 for taking out the pipe 11 from the pay-out machine 51 and sending it to the foam layer forming step section 33, and a curl correction device 5 provided between the pay-out machine 51 and the second take-up machine 52.
3 and 3. Pipe 11 used in the present embodiment
Is made of a flexible synthetic resin pipe and is long.

The feeding device 51 is composed of a rotary drum fixed to bearings, and the second take-up device 52 is composed of a pair of second conveyor belts 52a which are rotationally driven. And the pipe 11 is sent to the foam layer forming process unit 33 by the rotational driving of the second conveyor belt 52a.

The curl correction device 53 corrects a larger or smaller curl on the pipe 11, and as shown in FIG. 1, three correction rollers 53a are arranged alternately. Equipped with these correction rollers 5
The winding tendency of the pipe 11 is corrected by 3a. The straightening roller 53a has a shape in which the center of the roller surface in the longitudinal direction is tapered and recessed.

If the pipe is not flexible,
A straight pipe cut into a predetermined length may be continuously sent to the foam layer forming step unit 33 using a take-off machine, or as in a fourth embodiment shown in FIG. 16 described later, The pipe 11 manufactured in the extrusion line of the pipe manufacturing process section 32b having the pipe molding extruder 54 is taken up by the take-up machine 5
Alternatively, it may be continuously sent out to the foam layer forming process section 33 by the step 2.

Further, in the first embodiment, the feeding step of the pipe 11 is performed in parallel with the above-mentioned foam tube manufacturing step, the slit forming step and the step of expanding the diameter of the foam tube which will be described later.

Further, the foam layer forming process section 33 is provided with a break forming device 61 which continuously cuts the foam tube 2 in the longitudinal direction of the foam tube 2 in the slit forming process (slit forming process section). In the (pipe insertion step part), a pipe insertion device 62 for expanding the diameter of the foam tube 2 while being conveyed and inserting the pipe 11 from the cut 21 widened by the diameter expansion core 62a in the conveyed foam tube 2 is provided. In the foamed tube diameter reducing step (foamed tube diameter reducing step section), a foamed tube diameter reducing device 63 for reducing the diameter of the foamed tube 2 into which the pipe 11 is inserted is provided.

As shown in FIG. 1, the break forming device 61 is fixed to a support plate 64 and is linear and long so that breaks 21 are continuously formed in the foam tube 2 in the extrusion direction (longitudinal direction of the tube). A long cutter blade 61a, a first holding roller 61b provided so as to face the tip of the long cutter blade 61a, a long cutter blade 61a and a first holding roller 61b are attached and fixed to a support plate 64. And a supporting body 61c.

Further, as shown in FIG. 6, the long cutter blade 61a is attached to the support 61c so as to be able to move forward and backward in the radial direction with respect to the foam tube 2, and the long cutter blade 6a.
1a is fixed to a U-shaped holder 61d via a swinging fixing plate 61e, and the holder 61d is supported by a support body 61c so that it can be moved forward and backward with respect to the support body 61c by operating a position adjusting handle 61f. There is. By supporting the long cutter blade 61a so that the support 61c can move forward and backward, the cutting depth can be adjusted according to the thickness of the foam tube 2.

Further, the long cutter blade 61a is fixed to a swinging fixing plate 61e so that the cutting angle into the foam tube 2 can be changed, and the swinging fixing plate 61e is supported by a holder 61d (not shown). ), The angle adjusting dial 61g is attached to the support shaft, and the angle adjusting dial 61g is rotated to swing the swing fixing plate 61e to adjust the angle of the long cutter blade 61a. I am trying to do it.

The adjustment angle can be adjusted to a cutting angle of 30 to 45 degrees with respect to the surface of the foam tube 2. The cutting angle can be adjusted because the appropriate cutting angle changes depending on the surface temperature of the foam tube 2.

Then, the cut forming device 61 uses the cut 2
In forming No. 1, a cooling mechanism for cooling the foam tube 2 and the long cutter blade 61a at the time of forming the cut 21 is provided, and cooling for cooling the foam tube 2 and the long cutter blade 61a during the slit forming process. I have a process. The cooling may be performed by either the foam tube 2 or the long cutter blade 61a, or may be performed simultaneously.

Foam tube 2 and long cutter blade 61
As a means for cooling a, a cooling nozzle 61h is also attached to the support 61c on which the long cutter blade 61a is supported, and the discharge port of the cooling nozzle 61h is opposed to the surface of the foam tube 2 to cool the nozzle 61h. The cooling air discharged from the blower is blown onto the location of the cut 21 of the foam tube 2 to cool the foam tube 2 and the long cutter blade 61a.

The cooling nozzle 61h is provided so as to pass through the position adjusting handle 61f attached to the support 61c, the support 61c, and the holder 61d, and is aligned with the long cutter blade 61a. Is bent. Then, depending on the angle adjustment of the long cutter blade 61a, cooling air is blown directly from the outlet of the cooling nozzle 61h to the tip of the long cutter blade 61a, or slightly upstream of the tip of the long cutter blade 61a. Blow cooling air.

In the first embodiment, since the foam tube 2 and / or the long cutter blade 61a is forcibly cooled, the foam tube 2 in the manufacturing process of the foam tube 2
Even if the extrusion amount increases and the inner and outer surface temperatures of the foam tube 2 rise, or the friction heat of the long cutter blade 61a increases due to the large feed amount of the foam tube 2, the foam tube is formed when the cut 21 is formed. Since it is possible to cool the second cut formation position and / or the long cutter blade 61a, it is possible to prevent defective formation of the cut 21.

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. Then, the foam tube 2 to be conveyed is always positioned in the concave portion of the first holding roller 61b, so that the foam tube 2 is held at a predetermined position. Since the foam tube 2 is held by the first holding roller 61b, the slit 21 can be linearly formed at a predetermined position of the foam tube 2 by the long cutter blade 61a.

The first take-up machine 43 and the break forming device 6
A plurality of guide rollers 47 for guiding the foam tube 2 sent from the first take-up machine 43 to the cut forming device 61 are provided between the first and second take-up machines 43.

When making the break 21,
Not limited to the linear long cutter blade described above, for example, by applying a disc-shaped cutter blade fixed to the bearing to the side surface of the foam tube, and making a cut by rotating the disc-shaped cutter blade. Good.

Cut forming device 6 using a disc-shaped cutter blade
The first embodiment will be described with reference to FIG. 7. Figure 7
A slit forming device 6 using a disc-shaped cutter blade 61i shown in FIG.
1 is the same as that of the cut forming device 61 shown in FIG.

The cut forming device 61 using the disc-shaped cutter blade 61i is the same as the manufacturing device shown in FIG. 1, except that the long cutter blade 61a is replaced with the disc-shaped cutter blade 61i. A support plate 64 similar to 61
The disk-shaped cutter blade 61i, which is fixed to the foamed tube 2 and continuously cuts 21 in the extrusion direction (longitudinal direction of the tube) in the foamed tube 2, and the circumferential tip of the disk-shaped cutter blade 61i. First holding roller 61b provided
And the disc-shaped cutter blade 61i and the first holding roller 61b
Is attached and fixed to the support plate 64.

Further, as shown in FIG. 7, the disk-shaped cutter blade 61i 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. The holder 61d is fixed to the holder 61d via a rotary shaft 61j, and the holder 61d is supported by the support 61c so that the holder 61d can be moved back and forth by operating the position adjusting handle 61f.

Although not shown, the rotary shaft 61j for rotating the disc-shaped cutter blade 61i has one end connected to a motor, and the drive of this motor drives the rotary shaft 61j.
Is rotated to rotate the disc-shaped cutter blade 61i. Furthermore, the disc-shaped cutter blade 61i is
The foam tube 2 is rotated in the same direction as the delivery direction. The cutting depth can be adjusted according to the thickness of the foam tube 2 by supporting the disk-shaped cutter blade 61i so that the support 61c can move back and forth.

Further, the break forming device 61 shown in FIG.
Is provided with a cooling mechanism for cooling the disc-shaped cutter blade 61i when forming the cut 21, and in the slit forming step, the disc-shaped cutter blade 61i is formed.
A cooling step for cooling i is provided.

As a means for cooling the disc-shaped cutter blade 61i, the support 6 which supports the disc-shaped cutter blade 61i is used.
A cooling nozzle 61h is also attached to 1c so that the cooling air discharged from the cooling nozzle 61h is blown near the location where the cut 21 of the foam tube 2 is to be formed to cool the disk-shaped cutter blade 61i.

The cooling nozzle 61h includes a position adjusting handle 61f attached to the support 61c and the support 61c.
The disc-shaped cutter blade 61 by penetrating the holder and the holder 61d.
i is provided so as to cross i, and the cooling nozzle 61 is provided.
Cooling air is blown directly from the discharge port of h to the tip of the disk-shaped cutter blade 61i.

Since the disc-shaped cutter blade 61i is also forcibly cooled by the cut forming device 61 shown in FIG. 7, the foam tube 2 in the manufacturing process of the foam tube 2 is also improved.
Even if the extrusion amount increases and the temperature of the inner and outer surfaces of the foam tube 2 rises, or the frictional heat of the disc-shaped cutter blade 61i increases due to the large feed amount of the foam tube 2, the circle 21 is formed when the cut 21 is formed. Since the plate-shaped cutter blade 61i can be cooled, it is possible to prevent defective molding of the cut 21.

The pipe insertion device 62 of the first embodiment shown in FIG. 1 has a diameter-expanding core 62a for expanding the diameter of the foam tube 2 while conveying it, and a second core 62a for holding the foam tube 2.
And a holding roller 62b.

The expanded core 62a has a structure similar to that shown in FIGS.
As shown in FIG. 5, the upstream side in the tube transport direction is tapered, and the downstream end has a tubular shape with an opening. The downstream side in the tube transport direction is bent, and the pipe 11 is bent on the outer bent surface of the bent portion 62c. An insertion hole 62d is formed for inserting into the expanded core 62a. The insertion hole 62d serves as a guide passage for inserting the pipe 11 into the foam tube 2.

In the pipe insertion device 62, the foam tube 2
Is expanded along the tapered surface formed on the upstream side in the conveying direction of the expanded core 62a, and the expanded tube 2 is expanded so that the cut 21 is located on the outer bent surface of the bent portion. 62a.

Therefore, when the foam tube 2 is bent at the bent portion 62c of the expanded core 62a, the cut 21 further expands, and the expanded tube 2 further expands in diameter. 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 to facilitate insertion of the pipe 11.

The second holding roller 62b has a shape in which the center of the roller surface in the axial longitudinal direction is tapered and is rotatably supported by a support plate 64. Then, the foam tube 2 to be conveyed is always positioned in the concave portion of the second holding roller 62b so that the foam tube 2 is expanded.
The foam tube 2 is held by the second holding roller 62b and the expanded core 62a so as not to deviate from 2a.

In the present embodiment, a bent portion 62c is formed in the expanded core 62a, and the foam tube 2 is bent so that the cut 21 of the foam tube 2 is located on the outer bending surface, so that the feeding device 51 is provided. While linearly transporting the pipe 11 fed out from the pipe 11, the transport path of the foam tube 2 is merged with the transport path of the pipe 11 at the bending portion forming position, and the diameter is expanded from the cut 21 widened at the bending portion 62c. The pipe 11 can be easily fitted into the pipe 11 by inserting the pipe 11 into the insertion hole 62d of the core 62a.

At this time, in order to reduce the friction between the outer surface of the expanded core 62a and the inner surface of the foam tube 2, the expanded core 6 is formed.
The outer surface of 2a is preferably subjected to a processing treatment such as a fluororesin coating to reduce the frictional resistance.

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 side of the bent portion 62c) of the foam tube 2. At the same time, a cooling air supply pipe 62f for supplying cooling air into the expanded core 62a is connected to the expanded core 62a. The cooling air supplied from the cooling air supply pipe 62f into the expanded core 62a is discharged from the cooling air discharge hole 62e to cool the foam tube 2 inserted in the expanded core 62a from the inner surface side. There is.

The expanded core 62a shown in FIGS. 6 and 7 is used.
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, a surface treatment such as a fluororesin coating process was applied to the surface of the expanded core 62a.
As 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 expanded core 62a, or a spiral groove or expanded core 62a is formed on the outer surface of the expanded core 62a.
The frictional resistance may be reduced by forming a plurality of vertical grooves extending in the lengthwise direction or by forming a recess for reducing the contact area of the expanded tube 2 with the expanded core 62a.

A case where a plurality of annular grooves 62g extending in the circumferential direction are formed on the outer surface of the expanded core 62a will be described with reference to FIGS. 8 to 11. 9 is a cross-sectional view of the expanded core 62a shown in FIG. 8 taken along line XX. The expanded core 62a shown in FIG.
Is inserted into the foam tube 2 in a straight state, and a taper 62h having a tapered shape is formed on the upstream side in the tube transport direction, and the downstream side in the tube transport direction is bent.

An annular groove (recess) 6 extending in the circumferential direction is formed on the outer peripheral surface of the expanded core 62a on the upstream side of the bent portion 62c in the tube conveying direction and on the downstream side of the taper 62h.
A plurality of 2 g are formed. Further, an insertion hole 62d for inserting the pipe 11 into the expanded 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 foam tube 2, and has a downstream end opened.

Then, the annular groove 6 in the expanded core 62a.
As shown in FIGS. 8 and 9, a plurality of cooling air discharge holes 62e are formed in 2g, and a cooling air supply passage 62i for supplying cooling air is formed inside the expanded core 62a. From the cooling air supply passage 62i to the expanded core 6
The cooling air supplied to the inside of 2a is cooled by the cooling air discharge hole 62.
The foam tube 2 discharged from e and inserted into the expanded core 62a is cooled from the inner surface side.

In the expanded core 62a shown in FIG. 8, the pipe 11 is inserted straight into the foam tube 2 while bending the foam tube 2.
The expanded core 62a may have a linear shape like the expanded core 62a shown in FIG. The diameter-expanding core 62a shown in FIG. 10 has a tapered taper 62h on the upstream side in the tube conveying direction, and an annular groove (recessed portion) extending in the circumferential direction on the outer peripheral surface of the diameter-expanding core 62a on the downstream side of the taper 62h. ) 62 g are formed, and an insertion hole 62 d for inserting the pipe 11 into the diameter-expanding core 62 a is opened at the middle portion in the lengthwise direction of the diameter-expanding core 62 a. It is opened at the downstream end.

Insertion hole 62 of expanded core 62a shown in FIG.
d bends the shape of the guide passage so as to bend the pipe 11 inside the insertion hole 62d, and prevents the pipe 11 from coming into contact with the opening end of the insertion hole 62d when the pipe 11 is inserted into the insertion hole 62d. The opening area on the insertion side of the pipe 11 is formed wide. 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 conveyed linearly.

Further, as shown in FIG. 11, the expanded core 62
The diameter-expanding core 62 shown in FIG.
The pipe 11 may be inserted into the foam tube 2 while bending the foam tube 2 and the pipe 11 more gently than the angle a.

The diameter-expanding core 62a shown in FIG. 11 also has a tapered taper 62h on the upstream side in the tube conveying direction, and an annular ring extending in the circumferential direction on the outer peripheral surface of the diameter-expanding core 62a on the downstream side of the taper 62h. A plurality of grooves (recesses) 62g are formed, and the pipe 1 is provided at the middle portion in the length direction of the expanded core 62a.
The insertion hole 62d for inserting 1 into the diameter-expanding core 62a is opened, and the insertion hole 62d is opened at the downstream end of the diameter-expanding core 62a.

Further, as for the insertion hole 62d of the expanded core 62a shown in FIG. 11, the shape of the guide passage is curved so that the pipe 11 is curved inside the insertion hole 62d, and when the pipe 11 is inserted into the insertion hole 62d. In order to prevent the pipe 11 from coming into contact with the opening end of the insertion hole 62d, the opening area on the insertion side of the pipe 11 is formed wide.

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
The downstream side in the feeding direction of the is formed by a conical tapered cylindrical body 63a, which has a tapered shape.
By sending the foam tube 2 together with the pipe 11 and allowing the foam tube 2 to pass through the tubular body 63a, the cut portion 21 of the foam tube 2 expanded by the diameter-expanding core 62a is closed and the foam tube 2 is removed. The diameter can be reduced.

At this time, in order to reduce friction between the outer surface of the foam tube 2 and the inner surface of the tubular body 63a, the tubular body 63a is formed.
It is preferable to perform a processing treatment such as a fluororesin coating on the inner surface of the to reduce frictional resistance.

Further, in the skin layer forming step section 34, the skin layer forming extruder 71 in which the non-foaming thermoplastic resin composition for forming the skin layer 13 is melt-kneaded, and the foam tube 2 are introduced. Further, the molten resin extruded from the skin layer forming extruder 71 is supplied, and the skin layer forming die 72 for forming the skin layer 13 on the outer periphery of the foam tube 2 and the skin layer forming die 72 come out. Third receiving the covered pipe 1
And a take-off machine 73.

The skin layer forming extruder 71 is equipped with a raw material hopper 71a to which the thermoplastic resin composition is supplied.
The skin layer forming extruder 71 is connected to a skin layer forming die 72.

Although not shown, the skin layer molding die 72 was provided with a passage for passing the foam tube 2 and a resin supply passage for supplying the molten resin from the skin layer molding extruder 71. It is a crosshead die. Further, it is preferable to provide an uneven thickness adjusting mechanism at the outlet portion. Furthermore, in order to make it difficult for the heat of the molten resin flowing through the resin supply path to be transferred to the foam tube 2 inside the skin layer molding die 72,
It is preferable to insert a member having a heat insulating property such as a resin cylinder into the inner surface of the passage.

When the foam tube 2 is introduced together with the pipe 11 into the passage of the skin layer molding die 72, the molten resin for forming the skin layer is supplied from the resin supply passage to the outer surface of the foam tube 2, and the foam tube is formed. The outer peripheral surface of No. 2 is covered with the skin layer 13.

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 gas as the foaming agent is dissolved is foamed. After being extruded from the tube molding extruder 41, it is sent to the foam mold 42 connected to the foam tube molding extruder 41. While the foaming mold 42 is temperature-adjusted to the optimum foaming temperature, the foaming resin composition in the form of a tube is released from the foaming mold 42 to the atmospheric pressure, and a foaming tube having a uniform foaming state as shown in FIG. 2 is produced. The foam tube 2 coming out of the foam mold 42 is the first
It is sent to the foam layer forming step unit 33 by the take-off machine 43.

In the pipe feeding process section 32a, the pipe 11 is fed from the feeding device 51 by the second take-up machine 52, and the curl is corrected by the curl correction device 53.
It is sent to the foam layer forming step unit 33.

The foam tube 2 sent to the foam layer forming process section 33 by the first take-up machine 43 is used as the cut forming device 6.
The first cutter blade 61a makes continuous cuts 21 in the extrusion direction (longitudinal direction of the tube), resulting in the state shown in FIG.

The foam tube 2 is guided by the tapered surface formed on the upstream side of the expanded core 62a in the pipe insertion device 62 in the conveying direction, and the expanded tube 2 is press-fitted into the expanded core 62a to expand its diameter. Then, in the bent portion 62c of the expanded core 62a, the cut 21 of the foam tube 2 is further expanded, 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. To be done.

As described above, the foam tube 2 which has undergone the foam tube manufacturing step, the slit forming step and the foam tube expanding step, and the pipe 11 drawn out by the pipe feeding step.
Are joined together and the pipe 11 is inserted into the foam tube 2. First, the pipe 11 is connected to the second take-up machine 52.
And is inserted into the inside of the expanded core 62a through the notch.

When the pipe 11 passes through the expanded core 62a and is inserted into the expanded tube 2, the expanded tube contractor 63 contracts the expanded expanded tube 2. It At this time, the foam tube 2 is sent together with the pipe 11 into the tapered cylindrical body 63a and the foam tube 2 is passed through the cylindrical body 63a, so that the expanded tube 2 expanded by the expanded core 62a.
21 is easily closed and the diameter of the foam tube 2 is reduced, resulting in the state shown in FIG.

Next, the foam tube 2 whose diameter has been reduced with the pipe 11 inserted therein is used as the skin layer forming extruder 71.
It is introduced into the skin layer forming die 72 connected to the skin layer forming die 72, and the skin layer forming extrusion is performed while continuously passing the foam tube 2 in which the pipe 11 is inserted into the passage of the skin layer forming die 72. The molten resin for forming the skin layer is supplied from the machine 71. As a result, the outer peripheral surface of the foam tube 2 covering the outer periphery of the pipe 11 in the skin layer forming die 72 is further covered with the skin layer 13, and the covered pipe 1 shown in FIG. 5 is obtained.

The covering pipe 1 coming out of the skin layer molding die 72 is taken up by the 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, but when the pipe is not flexible, the coated pipe is cut into a certain length using a cutter.

As described above, 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 to be the foam layer 12 is manufactured, and then the foam layer 12 is foamed. Since the pipe 11 is inserted into the tube 2 so that the pipe 11 is covered with the foamed tube 2, the foamed layer 12 uniformly and highly foamed is obtained. Furthermore, since the series of steps for producing the coated pipe 1 can be performed in-line, the coated pipe 1 can be efficiently produced at low cost.

In the first embodiment, the tapered tubular body 63a is used as the foam tube diameter reducing device 63 in the foam tube diameter reducing step, but the foam tube diameter reducing step of reducing the diameter of the foam tube 2 into which the pipe 11 is inserted is used. Is not limited to the tapered cylindrical body 63a of the first embodiment described above, but includes a pair of pressing bodies that press the cut 21 of the expanded foam tube 2 in the butt direction, and the pressing body forms the foam tube. The diameter of the foam tube 2 may be reduced by sandwiching the two.

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 of FIG. 12, the central portion in the axial direction is recessed. There is one using a pair of rotatable rollers 63b having a tapered outer peripheral surface.

The coated pipe manufacturing apparatus of the second embodiment for manufacturing the coated pipe shown in FIG. 12 is the same as that of the foamed tube diameter reducing device 63, which is the foaming tube diameter reducing step in the manufacturing apparatus of the first embodiment. While changing the configuration,
A manufacturing method of the manufacturing apparatus according to the first embodiment is provided in which a break fusion step for melting the break 21 of the foam tube 2 is provided between the foam tube expanding step and the foam tube reducing step. Since they are the same, the same reference numerals are given to the same symbols and the description thereof will be omitted.

The foam tube diameter reducing device 63 of the second embodiment.
As shown in FIGS. 12 and 13, is composed of a pair of rotatable concave rollers 63b having a tapered outer peripheral surface with a concave center portion in the axial direction.

In the foam tube diameter-reducing device 63 of the second embodiment, the expanded foam tube 2 is introduced between two concave rollers 63b, and the cuts 21 of the foam tube 2 are brought into contact with each other by the concave rollers 63b. Foam tube 2 pressed in the direction and expanded by the expanded core 62a
The diameter of the foam tube 2 is reduced by closing the cut 21.

Further, on the upstream side of the concave roller 63b, as shown in FIGS. 12 and 13, the foam tube 2 is provided.
A cut fusing device 8 for fusing the cut 21 is provided, and the cut fusing device 8 is a hot air supply device (not shown).
And a hot air nozzle 81 serving as a heating unit. The break fusion device 8 melts the surface layer resin of the break 21 of the foam tube 2 into which the pipe 11 is inserted by the hot air discharged from the hot air nozzle 81, and the foam tube diameter reducing device 6
When the diameter is reduced by the two concave rollers 63b of No. 3, the cut 21 can be fused and the cross section of the fused portion can be brought into the state shown in FIG.

Although not shown, the hot air supply device is composed of a fan and a heater, the temperature of the hot air supplied to the hot air nozzle 81 can be controlled, and the temperature of the hot air supplied to the hot air nozzle 81 is controlled by the foam layer 12. By controlling the temperature to be equal to or higher than the melting point of the resin, the skin resin of the cut 21 can be melted.

The purpose of fusing the cuts 21 of the foamed tube 2 is to prevent the cuts 21 from opening in the skin layer forming process section 34. Whether the fusing is performed at regular intervals or continuously. Can be selected according to the purpose. By controlling the on / off of the fan of the hot air supply device, the surface layer resin of the cut 21 can be melted intermittently or continuously.

The cut surface fusion process performed by the cut fusion device 8 is not limited to the cut surface fusion of blowing hot air as described above, and the cut 21 directly formed on the hot plate composed of the heater and the metal plate.
May be brought into contact with each other to melt the surface layer resin of the cut 21.

As described above, in the second embodiment, since the foam tube diameter reducing device 63 uses the pair of rotatable rollers 63b having the tapered outer peripheral surface with the axial center recessed, the diameter is expanded. The diameter of the foam tube 2 can be easily reduced, and the melted cut 21 can be easily fused. Moreover, the foam tube 2 formed by the concave roller 63b
Since the diameter reducing operation can be performed without applying tension to the foam tube 2, it is possible to prevent only the foam tube 2 from contracting when the covering pipe is cut, and stabilize the product dimension. Can be achieved.

In the second embodiment, after the pipe inserting step and before the skin layer forming step, there is provided a cut fusion step of fusion-bonding the facing surfaces of the cut 21 of the foam tube 2 having the reduced diameter. Therefore, the cut 21 can be fused before the skin layer 13 is formed.
It is possible to surely prevent the cut 21 from opening during the formation of the, and it is possible to prevent the deterioration of quality.

Moreover, in the break fusion step, the surface resin of the break 21 of the foam tube 2 is melted by the hot air blown from the hot air nozzle 81 to fuse the facing surfaces of the break 21. It is possible to perform fusion bonding of the cut 21 portion without contacting the heat source directly and causing the foam tube 2 to lose its shape by a simple method.

Further, in the first embodiment, the foam tube supply step is constituted by the foam tube manufacturing step section 31a, and the foam tube diameter reducing step is performed by the foam tube diameter reducing device 6
Although the tapered tubular body 63a is used as 3, the foam tube 2 is prepared in a separate step in advance and wound around the reel 47 as in the third embodiment shown in FIG. 15, and the foam tube 2 is delivered from the reel 47. Foam tube feeding process unit 3 that sends the foam layer forming process unit 33 by the first take-up machine 43.
1b is provided, and in the same manner as in the second embodiment described above, a break fusion process using a hot air nozzle 81,
You may make it provide the foaming tube diameter reduction process by the foaming tube diameter reduction apparatus 63 which consists of two concave rollers 63b.

Further, in the first embodiment, in order to fit the foamed tube 2 to the pipe 11, the pipe feeding process section 32a is provided, and the pre-manufactured pipe 11 is fed from the feeding machine 51 to perform the pipe inserting process. However, as in the fourth embodiment shown in FIG. 16, a pipe molding extruder 54 in which the thermoplastic resin composition for forming the pipe 11 is melt-kneaded, and a pipe molding extruder 54. A pipe manufacturing process section 3 provided with a mold 55 for molding the pipe 11 into which the molten resin extruded from the mold is injected, and a second take-up machine 52 for receiving the pipe 11 coming out of the mold 55.
2b is provided, and similarly to the above-described second embodiment, a break fusion step by the hot air nozzle 81 and a foam tube diameter reducing step by the foam tube diameter reducing device 63 including two concave rollers 63b are provided. Good.

[0133]

EXAMPLES The present invention will be specifically described below with reference to examples, but the examples are merely examples and do not limit the present invention. (Example 1) Example 1 is the same as the above-described second embodiment (Fig. 1).
The manufacturing apparatus in 2) was used. Low-density polyethylene (manufactured by Nippon Polychem; product number "LF440HB") 100
Parts by weight and talc (manufactured by Sumika Color Co., Ltd., product number “SS-11-
20 ") 3 parts by weight was supplied to the raw material hopper 41a of the foaming tube molding extruder 41, and heated and melted in the foaming tube molding extruder 41. On the other hand, carbon dioxide gas was supplied as a foaming agent from the cylinder 44 to the foaming agent supply section 41b of the foaming tube molding extruder 41.

At this time, after the carbon dioxide gas discharged from the cylinder 44 is cooled by the cooling device 45, the metering pump 46 is used to
Resin extruding amount of the foaming tube molding extruder 41 is 10 kg /
It was supplied while being controlled to be 0.2 kg / h with respect to h, and kneaded at 120 ° C. in the foaming tube molding extruder 41. The temperature of the foaming mold 42 was set to 108 ° C., and an outlet having an inner diameter of 3 mm and an outer diameter of 6 mm was released to atmospheric pressure to obtain a uniform foamed tube 2 having an inner diameter of 18 mm, an outer diameter of 24 mm and a foaming ratio of about 6 times.

Then, the foam tube 2 is taken by the first take-up machine 43 and sent to the cut forming device 61 through the guide roller 47, and the cut tube 21 is continuously cut in the extruding direction by the long cutter blade 61a. I put it in. Subsequently, the expanded tube 2 was guided to the expanded core 62a, the opening was introduced into the expanded core 62a, and the cut 21 of the expanded tube 2 was widened at the bent portion 62c.

On the other hand, as the pipe 11, a cross-linked polyethylene pipe having an outer diameter of 17 mm is fed from the feeding device 51 by the second take-up device 52 at a speed of 3 m / min, inserted into the expanded core 62a, and covered with the foam tube 2. Pipe 11
Got Subsequently, a pair of rotatable concave rollers 63b each having a tapered central portion in the axial direction are pressed in the abutting direction by a cut of the foam tube 2 whose diameter is expanded, so that the expanded core 62a is expanded. Break 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 break was not performed.

On the other hand, 100 parts by weight of low-density polyethylene (manufactured by Nippon Polychem, product number "LF440HB") and pigment masterbatch (manufactured by Toyo Ink, product number "TET3MA1".
070RG ") 5 parts by weight of a mixture with the raw material hopper 71.
It was supplied to the skin layer forming extruder 71 from a and melt-kneaded at 170 ° C. Then, 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 die 72, and the skin layer 13 having a thickness of 200 μm is further provided on the outer periphery of the pipe 11 covered with the foam tube 2. coating Pas <br/> type 1 coated with thickness taken off by the third puller 73, was wound up by a winder.

[0138] (Example 2) pipe 11 which foam tube 2 is coated prior to introduction into the foam tube diameter device 63, provided with a slit fusing step, by setting the heater temperature of the hot air supply device 200 ° C. After the surface layer resin of the cut 21 was continuously melted through the hot air nozzle 81, the coated pipe was formed in the same manner as in Example 1 except that the cut tube 21 was continuously fused by being introduced into the foam tube diameter reducing device 63. Manufactured.
In Example 2, since the cut 21 was continuously fused,
It was possible to reliably prevent the cut 21 from separating when the skin layer 13 was formed.

(Embodiment 3) The fan of the hot air supply device is set to 10
After turning on / off every second to intermittently melt the cut 21, the cut tube 21 is introduced into the foam tube diameter reducing device 63.
A coated pipe was produced in the same manner as in Example 2 except that the resin was intermittently fused. In Example 3, the cuts 21 were intermittently fused, but it was possible to reliably prevent the cuts 21 from separating when the skin layer 13 was formed.

Example 4 In Example 4, the manufacturing apparatus in the third embodiment (FIG. 15) described above was used. The foam tube 2 is wound up in advance on a reel or the like, and as shown in FIG.
A coated pipe was manufactured in the same manner as in Example 1 except that the powder was sent to the foam layer forming step section 33. Since the foamed tube 2 is manufactured in advance and wound on a reel or the like, the heat generated during the formation of the cut 21 can be reduced as compared with the case where the foamed tube 2 is manufactured in-line, and the cut is formed. I was able to increase the line speed of time.

(Example 5) In Example 5, the manufacturing apparatus in the fourth embodiment (FIG. 16) described above was used. As shown in FIG. 16, a polyethylene pipe having an outer diameter of 17 mm is manufactured by an extrusion line arranged in parallel without feeding a preformed pipe, and a foam layer forming step is continuously performed by the second take-up 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.

Comparative Example A heat insulating pipe was manufactured by the method for manufacturing a heat insulating pipe in Example 1 disclosed in JP-A-61-293825. In the comparative example, a cross-linked high-density polyethylene pipe having an outer diameter of 17 mm was used as the pipe.

As the resin composition for forming the foam layer, 100 parts by weight of low-density polyethylene and P as a foaming agent were used.
A mixture of 1.5 parts by weight of -P'-oxybis- (benzenesulfonylhydrazide) was used. As the resin composition for forming the skin layer, high density polyethylene 1
A mixture of 00 parts by weight and 2.0 parts by weight of carbon black was used.

Then, using a long land die, while passing a pipe through the long land die, while simultaneously supplying the foam layer-forming resin composition and the skin layer-forming resin composition to the head by an extruder. The head and the long land die were passed through the pipe to simultaneously form a foam layer and a skin layer on the outer periphery of the pipe.

The coated pipe obtained in Comparative Example had a foam layer having a thickness of 3 mm and a skin layer having a thickness of 0.2 mm. As a result, only a coated pipe having an expansion ratio of about 2 was obtained.

Further, the expanded core 6 shown in FIG. 6 and FIG.
Comparison was made between the contracted state of the foam tube 2 when 2a was used and when the expanded core 62a shown in FIG. 8 was used. When the expanded core 62a shown in FIGS. 6 and 7 is used, the length of the foamed tube (1000
shrinkage dimension in the cutting end portion of a cutaway of the coated pipe after coating pipe formed against mm) whereas was 15 mm, when using the expanded cores 62a shown in FIG. 8,
The length of the foam tube (100
Shrinkage dimension in the cutting end portion of a cutaway of the coated pipe after coating pipe formed against 0 mm) was 1 mm.

From the above results, as shown in FIG. 8, the expanded core 62a is provided with the recess 62g for reducing the contact area with the inner surface of the foam tube 2, so that the expansion of the foam tube 2 due to frictional heat is reduced. Thus, the shrinkage of the foam tube 2 after forming the covered pipe could be suppressed.

[0148]

As described above, according to the coated pipe of the present invention, the foam layer is formed in a cylindrical shape, and the tubular foam layer has a longitudinal direction for inserting the pipe into the cylinder. are cut extending formation, so forming a skin layer that is continuous to the outer periphery of the foam layer having a cut, while uniformly high foamed foam layer is obtained, such connection work between coated pipes, coated pipes When the foam layer has to be removed from the pipe at the axial end of the, the foam layer can be easily peeled from the cut portion, so that the work of connecting the covering pipe can be easily performed. Become.

[0149] Further, according to the manufacturing method and manufacturing apparatus of the present invention, the outer circumference of the pipe, uniformly can be coated with high foamed foam layer, further coated pipe skin layer is coated on the outer periphery thereof Can be manufactured efficiently and at low cost.

[Brief description of 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 covered pipe of the present invention.

FIG. 3 is a cross-sectional view of the foam tube in which a slit is formed in the slit forming step in the method for manufacturing a covered 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 reduction process after the pipe is inserted into the foam tube in the pipe insertion process in the method for manufacturing a covered pipe of the present invention. is there.

It is produced by the production method of the coated pipe of the present invention; FIG
It is sectional drawing of a covering pipe.

FIG. 6 is a perspective view showing a diameter-expanding core of a cut forming device and a pipe inserting device in a manufacturing apparatus for manufacturing a covered pipe.

FIG. 7 is a perspective view showing another embodiment of a cut forming device in a manufacturing apparatus for manufacturing a covered pipe and a diameter-expanding 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 the covered pipe.

9 is a sectional view taken along line XX in FIG.

FIG. 10 is a perspective view showing another embodiment (straight diameter expanding core) of the expanding core of the pipe inserting device in the manufacturing apparatus for manufacturing the covered pipe.

FIG. 11 is a perspective view showing another embodiment of a diameter-expanding core of a pipe insertion device in a manufacturing apparatus for manufacturing a covered pipe (a foamed tube and a pipe are fitted with a bending-type diameter-expansion core while curving). 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 view showing 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 method for producing a covered pipe according to the present invention, and the break is melted. It is a pipe sectional view of the state where it was put on.

FIG. 15 is an overall configuration diagram of a manufacturing apparatus for manufacturing a coated pipe according to a third embodiment of the present invention.

FIG. 16 shows an overall configuration diagram of a manufacturing apparatus for manufacturing a coated pipe according to a fourth embodiment of the present invention.

[Explanation of reference numerals] 1 coated pipe 11 pipe 12 foam layer 13 skin layer 2 foam tube 21 cut 31a foam tube manufacturing process section 41 foam tube molding extruder 42 foam mold 61a, 61i cutter blade 62a expanded core 63a cylinder Body 71 Extruder for forming skin layer 72 Mold for forming skin layer

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F16L 9/04 F16L 9/04 9/12 9/12 9/16 9/16 // B29K 105: 04 B29K 105: 04 B29L 23:00 B29L 23:00 F Term (reference) 3H111 AA01 BA02 BA04 BA15 CA07 CA52 CB04 CB14 CB24 CC18 DA15 DB02 4F100 AK06 AT00A AT00C BA03 BA10A BA10C CA01B DD31 DJ01B EH17 JJ02 4F207 AA07 AG20 AE02 AE02 AE02 AE02 AE02 KB26 KF02

Claims (18)

[Claims] 1. A heat insulating pipe having a foam layer formed on the surface of a pipe, and a skin layer formed on the outer periphery of the foam layer, wherein the foam layer is formed in a tubular shape. A heat insulating pipe characterized in that a cut extending in the longitudinal direction for inserting the pipe into the cylinder is formed in the body layer, and a continuous skin layer is formed on the outer periphery of the foam layer having the cut. 2. The heat insulating pipe according to claim 1, wherein the cuts of the tubular foam layer are intermittently fused. 3. A method for producing a heat-insulating pipe in which a foam layer is formed on the surface of the pipe, and a skin layer is formed on the outer periphery of the foam layer, wherein a foam tube to be the foam layer is continuously supplied. While forming a slit in the foam tube by making a continuous cut in the longitudinal direction of the tube, a pipe insertion step of inserting the pipe into the foam tube from the cut while expanding the diameter of the foam tube with the cut, and inserting the pipe Characterized in that the heat insulation pipe is manufactured by a foaming tube reducing step of reducing the diameter of the foamed tube and a skin layer forming step of forming a skin layer on the outer periphery of the foamed tube where the pipe is inserted and reduced in diameter. Method of manufacturing heat insulating pipe. 4. The heat insulation according to claim 3, wherein the slit forming step includes a foam tube manufacturing step of independently extruding the foam tube for continuously supplying the foam tube. Pipe manufacturing method. 5. A foam tube manufacturing process extrudes a molten resin mixed with a physical foaming agent from a foam tube molding extruder and sends it to a foam mold connected to the foam tube molding extruder. 5. The foamed tube is manufactured by releasing from the above to atmospheric pressure.
The method for manufacturing an insulated pipe according to. 6. The method for producing a heat insulating pipe according to claim 5, wherein the physical foaming agent supplied to the molten resin in the foam tube molding extruder is carbon dioxide gas. 7. The method for producing a heat-insulated pipe according to claim 4, wherein the foamed tube extruded and foamed in the foamed tube manufacturing step has a foaming ratio of 5 times or more. . 8. The slit forming step has a cooling step of cooling a foam tube and / or a cutter blade for forming a cut line, according to any one of claims 3 to 7. Method of manufacturing heat insulating pipe. 9. In the pipe inserting step, a notched foam tube is introduced into a diameter-expanding core having a taper on the upstream side in the feed direction of the foam tube, and the foam tube is expanded while being conveyed. At the same time, the pipe is inserted through a slit opened in the foam tube to be conveyed, and the method for manufacturing a heat insulating pipe according to any one of claims 3 to 8. 10. The method for manufacturing an adiabatic pipe according to claim 3, wherein the pipe inserting step includes a cooling step of cooling the expanded tube whose diameter is expanded. 11. The step of reducing the diameter of a foamed tube is performed by feeding a foamed tube with a pipe inserted into a tubular body having a tapered shape on the downstream side of the foamed tube in the feeding direction to join the cut portion of the foamed tube. The method for manufacturing a heat insulating pipe according to claim 3, wherein the foamed tube is reduced in diameter. 12. The step of reducing the diameter of a foamed tube uses a pair of rotatable rollers having a tapered outer peripheral surface with a recessed central portion in the axial direction, and introduces a foamed tube expanded in diameter between the two rollers. Then, the diameter of the foamed tube is reduced by pressing the opposing surfaces of the cuts of the foamed tube by the pair of rollers in a direction to bring them into contact with each other.
0. The method for manufacturing a heat insulating pipe as described in 0. 13. The method according to claim 3, further comprising a cut-fusing step of fusing the facing surfaces of the cuts of the foamed tube having a reduced diameter after the pipe inserting step and before the skin layer forming step. The method for manufacturing the heat insulating pipe according to claim 12. 14. The heat insulation pipe manufacturing method according to claim 13, wherein in the cut fusion-bonding step, the surface layer resin in the cut portion of the foamed tube is melted by hot air to fuse the opposing surfaces of the cut. Method. 15. In the skin layer forming step, a foam tube having a pipe inserted therein and having a reduced diameter is fed into a skin layer forming mold, and the skin layer forming resin melted from the skin layer forming extruder is used as a skin. The method for producing a heat insulating pipe according to any one of claims 3 to 14, wherein the skin layer is formed on the outer circumference of the foamed tube by extruding it into a layer forming mold. 16. A heat insulating pipe manufacturing apparatus comprising a foam layer formed on the surface of a pipe and a skin layer formed on the outer periphery of the foam layer, wherein a foam tube to be the foam layer is continuously supplied. While forming a slit in the foam tube to make a continuous cut in the longitudinal direction of the tube, and a pipe insertion step section that inserts a pipe into the foam tube from the cut while expanding the diameter of the cut foam tube Is provided with a foamed tube reducing step for reducing the diameter of the foamed tube, and a skin layer forming step for forming a skin layer on the outer periphery of the foamed tube where the pipe is inserted and reduced in diameter. Equipment for manufacturing heat insulation pipes. 17. The pipe inserting step portion has a diameter-expanding core which has a taper on the upstream side in the feed direction of the foam tube and which has a taper shape, and which expands the diameter of the foam tube with a cut,
The diameter-expanding core is characterized in that it has a concave portion on the outer surface that is not in contact with the foam tube, and that it has a guide passage for inserting a pipe into the foam tube through a break in the foam tube expanded by the diameter expansion. The manufacturing apparatus of the heat insulation pipe according to claim 16. 18. The heat insulating pipe manufacturing apparatus according to claim 16 or 17, wherein the pipe inserting step portion is provided with a cooling mechanism for cooling the expanded tube whose diameter is expanded.