JP4081335B2 - Coated pipe manufacturing method and coated pipe manufacturing apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention provides a coated pipe in which a foam layer is formed on a pipe surface, and a skin layer is formed on the outer periphery of the foam layer Manufacturing method and coated pipe manufacturing apparatus About.
[0002]
[Prior art]
Conventionally, pipes, for example, synthetic resin pipes, copper pipes, steel pipes, etc., in order to give performance such as dew prevention, heat insulation, sound insulation, etc. Coated pipes are used.
[0003]
However, since the foam layer is weak in friction strength and scratch strength, there is a problem that if the foam layer is exposed to the outside, it is easily damaged by friction or scratch during construction or after piping.
[0004]
Therefore, for the purpose of protecting the surface of the foam layer, there has been proposed one in which a skin layer formed of a non-foamed synthetic resin is formed on the outer peripheral surface of the foam layer.
[0005]
For example, Japanese Patent Application Laid-Open No. 61-293825 discloses a method of manufacturing a heat insulating pipe in which a foam layer is formed on a pipe surface and a skin layer is formed on the outer periphery of the foam layer using an extruder. Yes. In this production method, a long land die is used for the die of the extruder, and the foam layer and the skin layer are piped by supplying the foam layer forming composition and the skin layer forming resin to the head of the extruder. It is disclosed that the foamed synthetic resin composition is foamed in a long land die and cooled at the same time on the outer periphery of the foamed synthetic resin composition.
[0006]
[Problems to be solved by the invention]
However, in the manufacturing method disclosed in Japanese Patent Laid-Open No. 61-293825, foaming is performed in a long land die and cooling is performed in the long land die. Therefore, the shape is fixed by being cooled in the long land die while foaming is restricted.
[0007]
Therefore, when a thermal decomposition type chemical foaming agent is used, it is cooled before the thermal decomposition is completely performed, so the gas pressure of the foaming agent dissolved in the resin is lowered and the expansion ratio is doubled. Only a moderate amount was obtained. Further, even when a physical foaming agent is used, when the foam layer resin composition foams in a state where foaming in the thickness direction is restricted by the long land die and the pipe, and comes out of the long land die, Since the foam layer was covered with the cooled and fixed skin layer, a high foaming ratio could not be obtained.
[0008]
Furthermore, since the conventional heat insulating pipe is formed by simultaneously extruding the foam layer and the skin layer on the outer periphery of the pipe, the foam layer is in close contact with the entire outer peripheral surface of the pipe, and a plurality of heat insulating pipes However, there is also a problem that the foaming layer is too close to the outer peripheral surface of the pipe so that the peeling work is difficult to perform.
[0009]
The present invention solves the problems in the method of manufacturing a coated pipe having a foam layer and a skin layer, and is formed from a pipe while forming a uniformly highly foamed foam layer on the outer periphery of the pipe. Providing a coated pipe that can be easily peeled off the foamed layer, and can efficiently form a coated pipe in which a foam layer that is uniformly highly foamed can be formed on the outer periphery of the pipe, and further, the outer skin layer is coated on the outer periphery. It aims to provide a method.
[0010]
[Means for Solving the Problems]
To achieve the above objective, As described herein The present invention is a coated pipe in which a foam layer is formed on a pipe surface, and a skin layer is formed on the outer periphery of the foam layer. The foam layer is formed in a cylindrical shape and has a cut extending in the longitudinal direction. The skin layer has a continuous continuity extending in the longitudinal direction.
[0011]
The pipe used in the present invention is, for example, a pipe having sound insulation, dew prevention, and heat insulation, for example, a metal pipe such as a steel pipe or a copper pipe, or a polyolefin pipe such as polyethylene, polypropylene, or polybden-1, Synthetic resin pipes such as cross-linked polyolefin pipes such as cross-linked polyethylene.
[0012]
Further, the foam layer coated on the outer periphery of the pipe is made of a foamed resin composition containing a thermoplastic resin that can be foamed in a low pressure zone by a foaming agent. Examples of the thermoplastic resin include polyethylene, polypropylene, polystyrene, chloride, and the like. Extrudable thermoplastic resins such as vinyl, vinylidene chloride, ethylene-vinyl acetate copolymer, chlorinated polyethylene, ethylene-propylene copolymer, ethylene-ethyl acrylate copolymer, polyethylene terephthalate, ABS resin, acrylic resin These may be used alone or in combination of two or more.
[0013]
The expansion ratio of the foam layer is preferably 5 times or more. If it is less than 5 times, the thermal conductivity tends to decrease, and if it is 5 times or more, the heat insulation / dew-proof performance is remarkably improved. In addition, as for the sound insulation performance, the sound absorbing effect is enhanced when the expansion ratio is 5 times or more.
As the bubble diameter of the foam layer, the smaller the thermal conductivity is, the better the heat insulation / dew-proof performance is. However, the higher the expansion ratio, the larger the bubble diameter inevitably, so 50 μm to 4 mm is preferable. . When it is larger than 4 mm, heat convection is generated in the bubbles and the thermal conductivity is increased, so that the heat insulation / dew prevention performance is lowered.
Further, when the open cell ratio defined by ASTM D2856 is high, the thermal conductivity is increased, and the heat insulation / dew prevention performance is lowered.
On the other hand, when used for sound insulation applications, if the open cell ratio is high, the sound absorbing effect is excellent, so 30% or more is preferable. This is because when the open cell ratio is higher, when sound enters the foam layer, it is likely to pass through a complicated path in the foam layer and be converted into thermal energy. In addition, since the skin layer is covered, the sound incident on the foam layer passes through a complicated path, is reflected by the skin layer, and then passes again through the complex path. It is converted to energy and absorbed.
[0014]
The skin layer coated on the outer periphery of the foam layer is preferably an extrudable resin and a thermoplastic resin having scratch resistance. Moreover, desired performance can be imparted by blending various additives. For example, by adding calcium carbonate, barium sulfate or the like to a thermoplastic resin, the specific gravity of the skin layer is increased, and sound insulation performance can be effectively imparted.
[0015]
In this specification According to the described invention, the foam layer is formed in a cylindrical shape, a cut extending in the longitudinal direction for inserting the pipe into the cylinder is formed, and further, the foam layer having the cut has a continuous outer periphery. As a result, the foam layer must be removed from the pipe at the axial end of the coated pipe, such as connecting the coated pipes, while obtaining a foam layer that is uniformly highly foamed. In this case, since the foam layer can be easily peeled from the cut portion, the connecting operation of the coated pipe is also facilitated. The term "compatible" here means that when the compound mixed with the chlorinated vinyl chloride resin is a polymer, the loss elastic modulus of the molded product obtained by kneading the two appears as a single peak in a temperature range of room temperature or higher. This means that when the compound to be mixed is other than a polymer, the compound is not significantly separated from the two kneaded melts.
[0016]
Also, In this specification The described invention the above In the invention of the coated pipe, the cut extending in the longitudinal direction of the foam layer is intermittently fused.
The intermittent fusion means that there are a portion fused along the cut and a portion not fused.
[0017]
In this specification According to the described invention, since the cuts in the foam layer are intermittently fused, it is possible to prevent the opening of the cut at the time of formation of the skin layer at the fused part, while the cuts are not cut. The foam layer can be easily peeled off from the pipe at the fused portion.
[0018]
Claim 1 The invention described in 1 is a method of manufacturing a coated pipe in which a foam layer is formed on a pipe surface, and a skin layer is formed on the outer periphery of the foam layer. A slit forming step for continuously cutting the foamed tube in the longitudinal direction of the tube while supplying, a pipe inserting step for inserting the pipe into the foamed tube while expanding the diameter of the foamed tube, and the pipe A covered pipe is manufactured by a foam tube diameter reducing step for reducing the diameter of the inserted foam tube, and a skin layer forming step for forming a skin layer on the outer periphery of the foam tube after the pipe is inserted and reduced in diameter. To do.
[0019]
As a means for supplying the foamed tube, the foamed tube to be a foam layer manufactured in advance may be wound on a reel or the like and supplied to the slit forming process, or a foamed tube manufacturing process may be provided. The foamed tube after manufacture may be directly supplied to the slit forming step.
[0020]
Claim 1 According to the invention described in the above, a series of steps for manufacturing the coated pipe can be performed in-line, and cooling with the outer diameter regulating mold is rate-controlled as in the prior art, thereby increasing the production speed. There is no problem that it cannot be done, and the coated pipe can be manufactured efficiently.
[0021]
Claim 2 The invention described in claim 1 In the method for manufacturing a coated pipe according to item 1, the slit forming step includes a foamed tube manufacturing step for extruding the foamed tube for continuously supplying the foamed tube.
[0022]
Claim 2 According to the invention described in (2), instead of directly forming the foam layer covering the surface of the pipe on the outer surface of the pipe, only the foam tube that becomes the foam layer is manufactured, and then a cut is formed in the foam tube. By inserting a pipe into the foam tube, a foam layer that is uniformly highly foamed can be obtained.
[0023]
The foaming agent for foaming the thermoplastic resin is not particularly limited as long as it does not degrade the thermoplastic resin. Or the physical foaming agent which is an easily volatile liquid is mentioned.
[0024]
Claim 3 The invention described in claim 2 In the method of manufacturing a coated pipe described in the above, the foamed tube manufacturing process sends a molten resin mixed with a physical foaming agent to a foaming mold in a state where the pressure is reduced from the foaming tube molding extruder, and the foamed mold is largely A foamed tube is produced by releasing the pressure.
[0025]
Examples of physical foaming agents include nitrogen, carbon dioxide, and air for gases, and low boiling point organic hydrocarbons such as propane, butane, and pentane for low-volatile liquids, alcohols, ketones, and esters for easily volatile liquids. Examples thereof include halogenated hydrocarbons such as compounds, monochlorodifluoromethane, dichlorodifluoromethane, dichlorotetrafluoroethane, etc., and these may be used alone or in combination of two or more.
According to the fifth aspect of the present invention, the physical foaming agent having a foaming pressure higher than that of the chemical foaming agent is melted in the resin and then released into the atmosphere to form the foamed tube. Foaming can be performed uniformly.
[0026]
Claim 4 The invention described in claim 3 In the method for producing a coated pipe according to the item 1, the physical foaming agent is carbon dioxide gas.
When using an easily volatile liquid as a physical foaming agent, there is a possibility of ozone layer destruction or flammability, so there are many things that require explosion-proof specifications as equipment, but use carbon dioxide as a physical foaming agent. Thus, there is no possibility of destruction of the ozone layer, the load on the environment can be reduced, and since it is nonflammable, no explosion-proof specification is required as equipment, and the equipment is simplified. Furthermore, since the solubility with respect to resin is also high, the foam layer uniformly highly foamed can be obtained.
[0027]
Claim 5 The invention described in claim 2 To claim 4 In the method for producing a coated pipe according to any one of the above, the foaming ratio of the foamed tube formed by extrusion foaming in the foamed tube production process is 5 times or more.
[0028]
The expansion ratio is defined by the following formula (1).
(Foaming ratio) = (Specific gravity of resin composition before foaming) / (Specific gravity of foam) (1)
Moreover, the reason why the preferable foaming ratio of the foam layer is set to 5 times or more is that the slope of decrease in thermal conductivity is large up to 5 times, and the dew prevention and heat insulation performance are remarkably improved in the region of 5 times or more. .
In addition, stabilizers, antioxidants, processing aids, lubricants, foaming aids, fillers, pigments, flame retardants and the like are added to the resin composition forming the foam layer or skin layer as necessary. be able to.
[0029]
Claim 6 The invention described in claim 1 To claim 5 In the method for manufacturing a coated pipe according to any one of the above, the slit forming step is performed by rotationally driving a rotatable circular cutter in the same direction as the advancing direction of the foamed tube.
Claim 6 According to the invention described in the above, in the slit forming step, the cutter is rotatable in a circular shape and is driven to rotate in the same direction as the direction of travel of the foamed tube, so that the foamed tube is not sufficiently solidified. A slit failure in which the thickness of the foam tube is reduced due to resistance by the cutter does not occur, and good slits can be continuously formed in the foam tube.
Moreover, it is preferable to control the circumferential speed of a circular cutter more than the linear speed of a foaming tube. This is because a part of the circular cutter is susceptible to the resistance of the foam tube.
[0030]
Claim 7 The invention described in claim 1 To claim 6 In the method for manufacturing a coated pipe according to any one of the above, the pipe insertion step is performed by introducing a foamed tube having a cut into a diameter-expanded core having a taper on the upstream side in the feed direction of the foamed tube. The diameter of the tube is increased while the tube is being transported, and the pipe is inserted from a slit that has been expanded into the foamed tube to be transported.
Claim 7 According to the invention described in (1), it is possible to easily widen the cut line of the foamed tube by the expanded core, and it is possible to easily insert the pipe into the foamed tube.
[0031]
Claim 8 The invention described in claim 1 To claim 7 In the method for manufacturing a coated pipe according to any one of the above, the pipe insertion step includes a cooling step for cooling the expanded foam tube.
[0032]
When a pipe is inserted into the foam tube while continuously feeding the foam tube, if the amount of the foam tube is increased, the temperature of the inner and outer surfaces of the foam tube may increase and the foam tube may be stretched. . When the foamed tube stretches, shrinkage of the foamed tube occurs after the formation of the skin layer, and even when the pipe end is exposed greatly after the production of the coated pipe, or when the coated pipe is cut halfway, It may be exposed greatly.
[0033]
Claim 8 The foam tube can be cooled in the cooling step in the pipe insertion process even when the amount of the foam tube delivered is increased. Therefore, the temperature rise can be suppressed and the expansion of the foam tube can be prevented. It is possible to prevent the pipe from being exposed from the pipe end.
[0034]
Claim 9 The invention described in claim 1 To claim 8 In the method for manufacturing a coated pipe according to any one of the above, the foaming tube diameter reducing step is performed by feeding the foamed tube into which the pipe is inserted into the inside of the cylindrical body in which the downstream side in the feeding direction of the foamed tube is tapered. The foamed tube is reduced in diameter by joining the cut portions of the tube.
According to invention of Claim 11, the diameter of the foamed tube expanded by the cylindrical body can be reduced easily.
[0035]
Claim 10 The invention described in claim 1 To claim 8 In the method for producing a coated pipe according to any one of the above, the foaming tube diameter reducing step uses a pair of rotatable rollers having a tapered outer peripheral surface with a recessed central portion in the axial direction, and between the two rollers. The expanded foamed tube is introduced, and the foamed tube is reduced in diameter by pressing the opposing surfaces of the foamed tube with the roller pair in the direction of attaching.
[0036]
Claim 10 According to the invention described in (2), the diameter of the expanded foamed tube can be easily reduced by using a pair of rotatable rollers having a tapered outer peripheral surface with a concave center in the axial direction. Furthermore, since the diameter of the foam tube can be reduced without applying tension to the foam tube, the foam tube can be prevented from shrinking when the coated pipe is cut, and the product dimensions can be stabilized. Can be achieved.
[0037]
Claim 11 The invention described in claim 1 To claim 10 In the method for producing a coated pipe according to any one of the above, a cut fusion process for fusing the opposing faces of the cuts of the reduced diameter foam tube after the foam tube diameter reduction process and before the skin layer forming step. It is characterized by having.
As a method of fusing the opposing surfaces of the cut of the foamed tube, there are a method of fusing the cut portion continuously in the length direction and a method of fusing intermittently along the cut.
[0038]
Claim 11 According to the invention described in (1), since the cut is fused before the skin layer is formed, it is possible to reliably prevent the cut portion from being opened during the formation of the skin layer, and to prevent deterioration in quality.
[0039]
Claim 12 The invention described in claim 11 In the method for manufacturing a coated pipe described in (1), the cut fusion process is characterized in that the opposed surfaces of the cut are fused by hot air.
Claim 12 According to the invention, the surface layer of the cut portion of the foamed tube can be directly brought into contact with a heat source by a simple method, and the cut portion can be fused without causing the foam tube to lose its shape.
[0040]
Claim 13 The invention described in claim 1 To claim 12 In the method for producing a coated pipe according to any one of the above, the skin layer forming step is performed by feeding the foamed tube, into which the pipe has been inserted and having a reduced diameter, into the skin layer forming mold and melting from the skin layer forming extruder. The skin layer forming resin is extruded into a skin layer forming mold to form a skin layer on the outer periphery of the foamed tube.
[0041]
If the thickness of the skin layer is too thin, the surface of the foam layer cannot be protected due to friction or scratching. Therefore, the thickness is preferably 100 μm or more, and more preferably 200 μm or more.
In addition, since the surface of the foam layer is highly likely to be transferred to the skin layer, a concealable pigment is added to the resin to improve the appearance, or embossing or embossing is applied. Is preferred.
Claim 13 According to the invention described in (1), the skin layer can be easily formed on the outer periphery of the foamed tube into which the pipe has been inserted to reduce the diameter.
[0042]
Claim 14 The invention described in 1 is an apparatus for manufacturing a coated pipe in which a foam layer is formed on a pipe surface, and a skin layer is formed on the outer periphery of the foam layer. A slit forming process part that continuously cuts the foam tube in the longitudinal direction of the tube while supplying it, and a pipe insertion process part that inserts the pipe into the foam tube from the cut while expanding the diameter of the foamed tube, A foam tube diameter reducing step for reducing the diameter of the foam tube into which the pipe is inserted, and a skin layer forming step for forming a skin layer on the outer periphery of the foam tube having the diameter reduced by being inserted with the pipe. It is a feature.
[0043]
Claim 14 According to the coated pipe manufacturing apparatus described in the above, the foam layer that covers the surface of the pipe is not directly molded on the outer surface of the pipe, but a foam is formed by forming a cut in the foamed tube that will be the foam layer. By inserting the pipe into the tube, the pipe is covered with the foamed tube, and a coated pipe with a skin layer formed on the outer periphery of the foamed tube can be manufactured, so the coating having a foam layer that is uniformly highly foamed A pipe is obtained.
[0044]
Claim 15 According to the coated pipe manufacturing apparatus described in claim 1, 14 In the coated pipe manufacturing apparatus described in (1), the slit forming step section includes a rotatable circular cutter and cooling equipment for the circular cutter.
[0045]
Claim 15 According to the invention described in (1), by using a rotatable circular cutter, it is possible to rotationally drive in the same direction as the advancing direction of the foamed tube, and resistance to the foamed tube can be suppressed. In addition, since the circular cutter is cooled, the foam tube has residual heat due to extrusion molding, and frictional heat is generated on the cutter blade, so that the temperature rise of the cut portion during the formation of the cut can be suppressed, and the temperature rise of the cut portion It is possible to prevent the formation of cuts due to the above.
[0046]
Claim 16 The invention described in claim 14 Or 15 In the coated pipe manufacturing apparatus according to claim 1, the pipe insertion process section has a taper that is tapered on the upstream side in the feed direction of the foamed tube, and includes a diameter-expanding core that expands the diameter of the foamed tube. The diameter core is provided with a recess that is not in contact with the foamed tube on the outer surface, and a guide passage for inserting a pipe into the foamed tube from the cut of the foamed tube widened by expanding the diameter. It is.
[0047]
The concave portion provided in the expanded core is formed by forming a plurality of annular grooves extending in the circumferential direction on the surface of the expanded core, forming a spiral groove on the surface of the expanded core, or extending in the feed direction of the foam tube. It is obtained by forming a plurality of grooves.
[0048]
Claim 16 According to the invention described in the above, the diameter of the expanded tube is expanded while keeping the inner surface of the expanded tube along the tapered outer peripheral surface of the expanded core, and the pipe is easily inserted into the expanded tube from the guide passage of the expanded core. Can be made. In addition, the recessed portion provided in the expanded core can reduce friction by reducing the contact area between the expanded core and the foam tube inner surface when the inner surface of the expanded tube is brought into contact with the outer peripheral surface of the expanded core. While the diameter of the expanded core can be smoothly expanded, the temperature rise of the foamed tube due to friction can be reduced.
[0049]
Claim 17 The invention described in claim 14 To claim 16 In the coated pipe manufacturing apparatus described in 1), the pipe insertion process unit includes a cooling mechanism that cools the expanded foam tube.
Claim 17 The foam tube can be cooled by the cooling mechanism in the pipe insertion process section even when the amount of the foam tube delivered is increased. Therefore, it is possible to prevent the expansion of the foam tube by suppressing the temperature rise of the foam tube. Further, it is possible to prevent the pipe from being exposed from the pipe end portion of the coated pipe after manufacture.
[0050]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 schematically shows a first embodiment of a manufacturing apparatus for manufacturing a coated pipe by the method for manufacturing a coated pipe according to the present invention, and the coated pipe manufacturing apparatus shown in FIG. The pipe 1 can be manufactured. As shown in FIG. 5, the coated pipe 1 has a foam layer 12 that is a sound insulating layer or a heat insulating layer formed on the surface of the pipe 11, and a skin layer 13 is formed on the surface of the foam layer 12.
[0051]
The coated pipe manufacturing apparatus according to the first embodiment is a slit forming step (slit) for making a cut line 21 in the foam tube 2 that becomes the foam layer 12 shown in FIG. Forming process), a pipe insertion process part (pipe insertion process) for inserting the pipe 11 into the foamed tube 2 from the cut line 21 while expanding the diameter of the foamed tube 2 containing the cut line 21, and foaming in which the pipe 11 is inserted The foamed tube diameter reducing step (foamed tube diameter reducing step) for reducing the diameter of the tube 2 to the state shown in FIG. 4 and the outer skin layer 13 formed on the outer periphery of the expanded foamed tube 2 with the pipe 11 inserted therein. Then, the coated pipe 1 is manufactured through each manufacturing process of the skin layer forming process section (skin layer forming process) in the state shown in FIG. The slit forming process section also has a foam tube manufacturing process for continuously supplying the foam tube 2.
[0052]
As shown in FIG. 1, in the coated pipe manufacturing apparatus according to the first embodiment, the foamed tube manufacturing process includes a foamed tube manufacturing process unit 31 a that extrudes the foamed tube 2 independently.
In addition, between the pipe insertion process and the foam tube diameter reduction process, the heating part 81 shown by the phantom line of FIG. 1 is provided, and the opposing surfaces of the cut line 21 of the foam tube 2 into which the pipe is inserted are intermittently. Or you may make it have the cut | fusion melt | fusion process of melt | disconnecting continuously.
[0053]
In this case, it is preferable that the heating unit is configured by a hot air nozzle 81 that blows hot air onto the foamed tube 2. The specific configuration and operational effects are the same as those of the heating unit shown in the second embodiment to be described later, and will be described in the second embodiment.
[0054]
The coated pipe manufacturing apparatus according to the first embodiment will be specifically described. As shown in FIG. 1, the coated pipe manufacturing apparatus according to the first embodiment repeats a foamed tube manufacturing process unit 31 a that extrudes the foamed tube 2 to be the foamed layer 12 and a flexible pipe 11. A pipe feeding process section 32a to be taken out, a foam layer forming process section 33 for performing a slit forming process, a pipe inserting process, and a foamed tube diameter reducing process, and a skin layer forming process section 34 for performing a skin layer forming process. Yes.
[0055]
The foam tube manufacturing process section 31a includes a foam tube forming extruder 41 in which a foamable thermoplastic resin composition for forming the foam layer 12 is melt-kneaded, and a melt extruded from the foam tube forming extruder 41. A foaming mold 42 for molding the foamed tube 2 by injecting resin and a first take-up machine 43 for receiving the foamed tube 2 coming out of the foaming mold 42 are provided.
[0056]
The extruder 41 for forming a foamed tube includes a raw material hopper 41a to which a thermoplastic resin composition is supplied and a foaming agent supply unit 41b, and a resin composition for forming the foam layer 12 from the raw material hopper 41a. On the other hand, the physical foaming agent in the cylinder 44 is supplied into the foaming tube forming extruder 41 from the foaming agent supply unit 41b.
[0057]
A cooling device 45 and a metering pump 46 are provided in the supply path between the cylinder 44 and the foaming agent supply unit 41b. In this embodiment, carbon dioxide is used as the physical foaming agent. In order to increase the temperature, 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.
[0058]
The metering pump 46 controls the supply amount of the foaming agent into the foaming tube molding extruder 41 so that the target foaming ratio is obtained with respect to the resin extrusion amount of the foaming tube molding extruder 41. ing.
[0059]
The foaming ratio can be controlled by the amount of foaming agent dissolved in the molten resin. When carbon dioxide is used as the physical foaming agent, 1 wt% or more of carbon dioxide gas is dissolved in the molten resin in order to obtain a foaming ratio of 5 times or more. It is necessary to let
[0060]
However, if carbon dioxide gas is supplied excessively with respect to the target magnification, bubble breakage occurs at the outlet of the foaming mold 42 and gas escape is promoted. As a result, the magnification does not increase so that bubble breakage does not occur. It is necessary to control the amount of blowing agent supplied.
[0061]
In the foaming tube forming extruder 41, the foaming agent is dissolved in the molten resin from the foaming agent supply unit 41b while heating and melting the resin composition supplied from the raw material hopper 41a. The molten resin is extruded into a foaming mold 42 connected to 41.
[0062]
Further, in the foam tube forming extruder 41, a screw groove provided in the foam tube forming extruder 41 so that the foaming agent can be stably supplied into the foam tube forming extruder 41 from the foaming agent supply section 41b. The depth is formed so as to be deeper in a portion facing the position where the foaming agent supply part 41b is formed, and the pressure of the molten resin is temporarily lowered when the foaming agent is supplied. In order to efficiently dissolve the foaming agent in the molten resin, it is preferable to provide a mixing element such as a dull mage in the screw.
[0063]
Although not shown, the foaming mold 42 is formed of an inner core and an outer mold in order to be formed into a tube shape. The inner core is held by a bridge, and the outer mold is a band heater or a medium such as oil. The temperature can be adjusted.
[0064]
The first take-up machine 43 is composed of a pair of first transport belts 43a that are rotationally driven. The foam tube 2 is sandwiched between the first transport belts 43a and the first transport belt 43a is rotationally driven. Is sent out to the foam layer forming process section 33.
[0065]
Therefore, in the foaming mold 42, the temperature of the resin composition supplied in a decompressed state from the foaming tube molding extruder 41 is adjusted to the optimum foaming temperature, and the resin composition in the tube state is formed from the foaming mold 42. By being released into the atmospheric pressure, the resin composition is foamed to produce a uniform highly foamed foamed tube 2 as shown in FIG.
[0066]
The optimum temperature for foaming varies depending on the amount of foaming agent dissolved in the molten resin, so the plasticizing effect of the resin varies, so if the resin is crystalline, the melting point is ± 10 ° C. If the resin is amorphous, the glass transition It is preferable to set the temperature within a range of ± 10 ° C. Moreover, it is preferable to provide the thickness adjustment mechanism in the foaming die 42.
[0067]
As shown in FIG. 1, the pipe feeding process unit 32 a that feeds the pipe 11 feeds the pipe 11 from the feeding machine 51 and the feeding machine 51 to which the pipe 11 that has been manufactured and wound in advance by another extruder is attached. And a second take-up machine 52 for sending out to the foam layer forming process unit 33, and a curl correction device 53 provided between the feeding machine 51 and the second take-up machine 52.
The pipe 11 used in the present embodiment is formed of a synthetic resin pipe having flexibility and is long.
[0068]
The feeding machine 51 is composed of a rotating drum fixed to a bearing, and the second take-up machine 52 is constituted by a pair of second conveyor belts 52a that are rotationally driven, and the pipe 11 is sandwiched between the second conveyor belts 52a. Thus, the pipe 11 is sent out to the foam layer forming process section 33 by the rotational driving of the second transport belt 52a.
[0069]
Further, the curl correction device 53 corrects curl attached to the pipe 11, and includes three correcting rollers 53a arranged alternately as shown in FIG. The roller 53a corrects the curl of the pipe 11. The correction roller 53a has a tapered shape in which the center in the longitudinal direction of the roller surface is tapered.
[0070]
If the pipe is not flexible, a straight pipe cut to a predetermined length may be continuously sent to the foam layer forming process unit 33 using a take-up machine, which will be described later. As in the fourth embodiment shown in FIG. 16, the pipe 11 manufactured in the extrusion line of the pipe manufacturing process section 32 b having the pipe forming extruder 54 is continuously fed to the foam layer forming process section 33 by the take-up machine 52. You may make it send out.
[0071]
Furthermore, in 1st Embodiment, the drawing | feeding-out process of the pipe 11 is performed in parallel with the above-mentioned foaming tube manufacturing process, the slit formation process mentioned later, and the process of expanding the diameter of a foaming tube.
[0072]
Further, the foam layer forming process unit 33 includes a cut forming device 61 that continuously cuts the foam tube 2 in the longitudinal direction of the tube in the slit forming process (slit forming process part), and inserts a cut 21 into the pipe insertion process (pipe insertion process). In the process section), the foam tube 2 is provided with a pipe insertion device 62 for expanding the diameter while conveying the foam tube 2 and inserting the pipe 11 into the conveyed foam tube 2 from the cut 21 widened by the diameter-expanding core 62a. In the diameter reduction process (foaming tube diameter reducing process part), a foaming tube diameter reducing device 63 for reducing the diameter of the foaming tube 2 into which the pipe 11 is inserted is provided.
[0073]
As shown in FIG. 1, the cut forming device 61 is fixed to a support plate 64, and is a linear and long long piece that continuously cuts the cut 21 in the extrusion direction (longitudinal direction of the tube) into the foamed tube 2. A cutter blade 61a, a first holding roller 61b provided so as to face the tip of the long cutter blade 61a, and a support to which the long cutter blade 61a and the first holding roller 61b are attached and fixed to the support plate 64 61c.
[0074]
Further, as shown in FIG. 6, the long cutter blade 61a is attached to the support body 61c so as to be able to advance and retract in the radial direction with respect to the foamed tube 2, and the long cutter blade 61a is attached to the U-shaped holder 61d. The holder 61d is supported by the support 61c so that it can be advanced and retracted by operating the position adjusting handle 61f with respect to the support 61c. By supporting the long cutter blade 61a on the support body 61c so as to advance and retreat, the depth of cut can be adjusted according to the thickness of the foamed tube 2.
[0075]
Further, the long cutter blade 61a is fixed to the swinging fixing plate 61e so that the cutting angle into the foamed tube 2 can be changed, and the swinging fixing plate 61e is swung to the holder 61d by a support shaft (not shown). The angle adjustment dial 61g is attached to the support shaft, and the angle adjustment dial 61g is rotated so that the fixed plate 61e is swung to adjust the angle of the long cutter blade 61a. ing.
[0076]
The adjustment angle can be adjusted from 30 degrees to 45 degrees with respect to the surface of the foam tube 2. The reason why the cutting angle can be adjusted is that the appropriate cutting angle changes depending on the surface temperature of the foamed tube 2.
[0077]
The cut forming device 61 includes a cooling mechanism that cools the foamed tube 2 and the long cutter blade 61a when the cut 21 is formed when the cut 21 is formed. A cooling process for cooling the long cutter blade 61a is provided. The cooling may be performed by either the foam tube 2 or the long cutter blade 61a, or may be performed at the same time.
[0078]
As a means for cooling the foamed tube 2 and the long cutter blade 61a, the 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 connected to the surface of the foamed tube 2 The cooling air discharged from the cooling nozzle 61h is blown to the location where the cut 21 of the foam tube 2 is formed to cool the foam tube 2 and the long cutter blade 61a.
[0079]
The cooling nozzle 61h is provided to penetrate the position adjusting handle 61f attached to the support 61c, the support 61c, and the holder 61d so as to be aligned with the long cutter blade 61a, and bends the discharge side tip. ing. And according to the angle adjustment of the long cutter blade 61a from the discharge port of the cooling nozzle 61h, the cooling air is blown directly on the tip of the long cutter blade 61a, or slightly upstream from the tip of the long cutter blade 61a. Spray cooling air.
[0080]
In the first embodiment, since the foam tube 2 and / or the long cutter blade 61a are forcibly cooled, the amount of extrusion of the foam tube 2 in the production process of the foam tube 2 is increased and the inner and outer surface temperatures of the foam tube 2 are increased. Even when the feed rate of the foam tube 2 is large and the frictional heat of the long cutter blade 61a rises, when the cut 21 is formed, the cut forming position of the foam tube 2 and / or the long cutter blade 61a Therefore, it is possible to prevent the molding failure of the cut 21 from occurring.
[0081]
Further, although not shown, the first holding roller 61b has a tapered shape in which the center in the longitudinal direction of the roller surface is tapered and is rotatably supported by the support body 61c. And the foaming tube 2 is hold | maintained in a predetermined position by always positioning the foaming tube 2 conveyed in the recessed part of the 1st holding roller 61b. Since the foam tube 2 is held by the first holding roller 61b, the cut line 21 can be linearly formed at a predetermined position of the foam tube 2 by the long cutter blade 61a.
[0082]
A plurality of guide rollers 47 are provided between the first take-up machine 43 and the cut forming device 61 for guiding the foamed tube 2 sent out from the first take-up machine 43 to the cut forming device 61.
[0083]
In addition, in making the cut line 21, it is not limited to the above-described linear long cutter blade. For example, the disk-shaped cutter blade fixed to the bearing is applied to the side surface of the foam tube, and the disk-shaped cutter blade You may make it cut | disconnect by rotation.
[0084]
An embodiment of the cut forming device 61 using a disc-like cutter blade will be described with reference to FIG. 7 is indicated by the same reference numeral for the same member as the cut forming device 61 shown in FIG.
[0085]
The cut forming device 61 by the disc-shaped cutter blade 61i is the same as the cut forming device 61 shown in FIG. 1 except that the long cutter blade 61a is replaced with the disc-shaped cutter blade 61i in the manufacturing apparatus shown in FIG. The disk-shaped cutter blade 61i is fixed to the support plate 64 and continuously cuts the foam tube 2 in the extrusion direction (longitudinal direction of the tube), and the front end of the disk-shaped cutter blade 61i faces the circumferential tip. The first holding roller 61b provided as described above, and the support body 61c to which the disc-shaped cutter blade 61i and the first holding roller 61b are attached and fixed to the support plate 64 are provided.
[0086]
Further, as shown in FIG. 7, the disc-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 foamed tube 2, and the disc-shaped cutter blade 61i is attached to a U-shaped holder. The holder 61d is supported on the support 61c so that it can be advanced and retracted by operating the position adjusting handle 61f with respect to the support 61c.
[0087]
Although the rotary shaft 61j for rotating the disk-shaped cutter blade 61i is not shown, one end portion is connected to a motor, and the rotary shaft 61j is driven to rotate by driving the motor to rotate the disk-shaped cutter blade. 61i is rotated. Furthermore, the disk-shaped cutter blade 61i is rotated in the same direction as the feeding direction of the foamed tube 2.
And the cutting depth can be adjusted according to the thickness of the foamed tube 2 by making the support body 61c support the disk-shaped cutter blade 61i so that advancement / retraction is possible.
[0088]
Furthermore, the cut forming device 61 shown in FIG. 7 is provided with a cooling mechanism for cooling the disc-shaped cutter blade 61i when forming the cut 21 in forming the cut 21, and in the slit forming step, the disc-shaped cutter blade 61i. A cooling process is performed to perform cooling.
[0089]
As a means for cooling the disk-shaped cutter blade 61i, a cooling nozzle 61h is also attached to the support 61c on which the disk-shaped cutter blade 61i is supported, and the cooling air discharged from the cooling nozzle 61h is supplied to the foaming tube 2. The disk-shaped cutter blade 61i is cooled by spraying the vicinity of the portion where the cut 21 is to be formed.
[0090]
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 so as to cross the disc-shaped cutter blade 61i. Cooling air is blown directly from the discharge port to the tip of the disc-shaped cutter blade 61i.
[0091]
7 also forcibly cools the disk-shaped cutter blade 61i, the amount of extrusion of the foamed tube 2 in the manufacturing process of the foamed tube 2 is increased, and the inner and outer surface temperatures of the foamed tube 2 are increased. Even when the amount of feed of the foamed tube 2 increases and the frictional heat of the disk-shaped cutter blade 61i increases, the disk-shaped cutter blade 61i can be cooled when the cut 21 is formed. It is possible to prevent defective molding.
[0092]
The pipe insertion device 62 according to the first embodiment shown in FIG. 1 includes a diameter-expanding core 62a that expands the diameter while conveying the foamed tube 2, and a second holding roller 62b that holds the foamed tube 2.
[0093]
As shown in FIGS. 1, 6, and 7, the diameter-expanding core 62 a has a cylindrical shape in which the upstream side in the tube conveyance direction is tapered and the downstream end is opened, and the downstream side in the tube conveyance direction is bent. An insertion hole 62d for inserting the pipe 11 into the enlarged core 62a is formed on the outer bent surface of the bent portion 62c. The insertion hole 62d serves as a guide passage for inserting the pipe 11 into the foamed tube 2.
[0094]
In the pipe insertion device 62, the diameter of the foamed tube 2 is increased while being along a tapered surface formed on the upstream side of the diameter-enlarged core 62a in the conveying direction. It is introduced into the enlarged core 62a so as to be positioned on the surface.
[0095]
Therefore, when the foamed tube 2 is bent at the bent portion 62c of the diameter-expanded core 62a, the cut 21 is further expanded, and the diameter of the foamed tube 2 is further expanded. By using the bent diameter expanded core 62a, the cut line 21 of the foamed tube 2 can be easily expanded by the bent portion 62c of the expanded diameter core 62a so that the pipe 11 can be easily inserted.
[0096]
The second holding roller 62b has a shape in which the center in the axial direction of the roller surface is recessed in a tapered shape, and is rotatably supported by the support plate 64. Then, the foamed tube 2 to be conveyed is always positioned in the recess of the second holding roller 62b, so that the foamed tube 2 is foamed by the second holding roller 62b and the diameter-expanded core 62a so as not to deviate from the diameter-expanded core 62a. The tube 2 is held.
[0097]
In the present embodiment, the bent portion 62c is formed in the diameter-expanded core 62a, and the foamed tube 2 is bent so that the cut line 21 of the foamed tube 2 is located on the outer bent surface. While the pipe 11 is linearly conveyed, the conveyance path of the foamed tube 2 is merged with the conveyance path of the pipe 11 at the bent portion forming position, and from the cut 21 widened at the bent portion 62c, The pipe 11 is inserted into the insertion hole 62d so that the foamed tube 2 can be easily fitted into the pipe 11.
[0098]
At this time, in order to reduce the friction between the outer surface of the enlarged core 62a and the inner surface of the foamed tube 2, it is preferable to apply a processing treatment such as a fluororesin coating to the outer surface of the enlarged core 62a.
[0099]
Further, as shown in FIGS. 6 and 7, a plurality of cooling air discharge holes 62e are formed on the outer peripheral surface of the expanded core 62a on the insertion side (upstream side of the bent portion 62c) of the foamed tube 2 and expanded. A cooling air supply pipe 62f for supplying cooling air to the inside of the diameter core 62a is connected to the diameter expansion core 62a. The cooling air supplied from the cooling air supply pipe 62f to the inside of the enlarged core 62a is discharged from the cooling air discharge hole 62e to cool the foamed tube 2 inserted into the enlarged core 62a from the inner surface side. Yes.
[0100]
In addition, in the diameter-expanded core 62a shown in FIG. 6 and FIG. 7, in order to reduce the frictional resistance between the outer surface of the diameter-expanded core 62a and the inner surface of the foamed tube 2, the surface of the diameter-expanded core 62a is coated with fluororesin, etc. 8 to 11, 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 enlarged core 62a, or on the outer surface of the enlarged core 62a. Friction resistance is reduced by forming a plurality of longitudinal grooves extending in the longitudinal direction of the spiral groove or the expanded core 62a, or forming a recess for reducing the contact area of the foamed tube 2 with the expanded core 62a. You may do it.
[0101]
A case where a plurality of annular grooves 62g extending in the circumferential direction is formed on the outer surface of the diameter-expanded core 62a will be described with reference to FIGS. 9 is a cross-sectional view taken along line XX of the diameter-expanded core 62a shown in FIG.
The diameter-expanded core 62a shown in FIG. 8 is formed by bending the foam tube 2 and inserting the pipe 11 into the foam tube 2 in a straight state. The taper is tapered toward the upstream side in the tube conveyance direction. 62h is formed, and the downstream side in the tube conveying direction is bent.
[0102]
A plurality of annular grooves (concave portions) 62g extending in the circumferential direction are formed on the outer peripheral surface of the diameter-enlarged core 62a upstream of the bent portion 62c and downstream of the taper 62h.
Further, an insertion hole 62d for inserting the pipe 11 into the enlarged core 62a is formed on the outer bent surface of the bent portion 62c. The insertion hole 62d serves as a guide passage for inserting the pipe 11 into the foamed tube 2, and the downstream end is opened.
[0103]
Then, as shown in FIGS. 8 and 9, a plurality of cooling air discharge holes 62e are formed in the annular groove 62g in the diameter-expanding core 62a, and cooling air supply for supplying cooling air to the inside of the diameter-expanding core 62a. A passage 62i is formed. The cooling air supplied from the cooling air supply passage 62i to the inside of the enlarged core 62a is discharged from the cooling air discharge hole 62e to cool the foamed tube 2 inserted into the enlarged core 62a from the inner surface side. Yes.
[0104]
Further, in the enlarged core 62a shown in FIG. 8, the pipe 11 is inserted into the foamed tube 2 while being bent, while the foamed tube 2 is bent, but like the enlarged core 62a shown in FIG. The shape of the expanded core 62a may be linear.
The diameter-expanded core 62a shown in FIG. 10 has a tapered taper 62h on the upstream side in the tube conveying direction, and an annular groove (concave part) extending in the circumferential direction on the outer peripheral surface of the diameter-expanded core 62a on the downstream side of the taper 62h. ) A plurality of 62g are formed, and an insertion hole 62d for inserting the pipe 11 into the enlarged core 62a is opened at the middle in the longitudinal direction of the enlarged core 62a. The inserted hole 62d is formed in the enlarged core 62a. It opens to the downstream end.
[0105]
The insertion hole 62d of the expanded core 62a shown in FIG. 10 curves the shape of the guide passage so that the pipe 11 is curved inside the insertion hole 62d, and the pipe 11 is inserted when the pipe 11 is inserted into the insertion hole 62d. The opening area on the pipe 11 insertion side is wide so as not to contact the opening end of the hole 62d.
10, the pipe 11 can be bent and inserted into the foamed tube 2 while the foamed tube 2 is conveyed linearly.
[0106]
Further, as shown in FIG. 11, the diameter-expanding core 62a is bent. However, the bending angle is made gentler than that of the diameter-expanding core 62a shown in FIG. The pipe 11 may be inserted into the tube 2.
[0107]
The diameter-expanded core 62a shown in FIG. 11 also has a tapered taper 62h on the upstream side in the tube conveying direction, and an annular groove (concave part) extending in the circumferential direction on the outer peripheral surface of the diameter-expanded core 62a on the downstream side of the taper 62h. ) A plurality of 62g are formed, and an insertion hole 62d for inserting the pipe 11 into the enlarged core 62a is opened at the middle in the longitudinal direction of the enlarged core 62a. The inserted hole 62d is formed in the enlarged core 62a. It opens to the downstream end.
[0108]
Further, the insertion hole 62d of the diameter-expanded core 62a shown in FIG. 11 also curves the shape of the guide passage so that the pipe 11 is curved inside the insertion hole 62d, and the pipe 11 is inserted when the pipe 11 is inserted into the insertion hole 62d. However, the opening area on the insertion side of the pipe 11 is made large so as not to contact the opening end of the insertion hole 62d.
[0109]
Next, the foamed tube diameter reducing device 63 in the foamed tube diameter reducing process in the first embodiment shown in FIG. 1 will be described. The foaming tube diameter reducing device 63 for reducing the diameter of the foaming tube 2 in which the pipe 11 is inserted is configured by a conical tapered cylindrical body 63a in which the downstream side in the feed direction of the foaming tube 2 is tapered. The foamed tube 2 is fed into the cylindrical body 63a together with the pipe 11, and the foamed tube 2 is allowed to pass through the cylindrical body 63a. The diameter of the tube 2 can be reduced.
[0110]
At this time, in order to reduce the friction between the outer surface of the foamed tube 2 and the inner surface of the cylindrical body 63a, it is preferable to apply a processing process such as a fluororesin coating to the inner surface of the cylindrical body 63a.
[0111]
Furthermore, the skin layer forming process section 34 is provided with a skin layer forming extruder 71 into which the non-foamable thermoplastic resin composition for forming the skin layer 13 is melt-kneaded, the foam tube 2 and the skin layer. A skin layer molding die 72 for feeding the molten resin extruded from the layer molding extruder 71 to mold the skin layer 13 on the outer periphery of the foamed tube 2, and a coated pipe coming out of the skin layer molding die 72 And a third take-up machine 73 that receives 1.
[0112]
The skin layer molding extruder 71 includes a raw material hopper 71a to which a thermoplastic resin composition is supplied. The skin layer molding extruder 71 is connected to a skin layer molding die 72.
[0113]
Although not shown, the skin layer molding die 72 is a crosshead die in which a passage through which the foamed tube 2 passes and a resin supply path for supplying molten resin from the skin layer molding extruder 71 are formed. It is. Moreover, it is preferable to provide an uneven thickness adjusting mechanism at the outlet. Furthermore, in order to make it difficult for the heat of the molten resin flowing through the resin supply path to be transmitted to the foamed tube 2, a member such as a resin tube having heat insulation is inserted into the inner surface of the passage inside the skin layer molding die 72. It is preferable to keep it.
[0114]
When the foam tube 2 is introduced into the passage of the skin layer molding die 72 together with the pipe 11, 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 outer periphery of the foam tube 2. The surface is covered with the skin layer 13.
[0115]
According to the coated pipe manufacturing apparatus in the first embodiment described above, first, in the foamed tube manufacturing process section 31a, the molten resin composition in which carbon dioxide gas as a foaming agent is dissolved is extruded from the foamed tube forming extruder 41. After that, it is sent to the foaming mold 42 connected to the foaming tube forming extruder 41. While the foaming mold 42 is adjusted to the optimum foaming temperature, the foamed resin composition formed into a tube shape from the foaming mold 42 is released to atmospheric pressure, and the foamed tube having a uniform foaming state as shown in FIG. 2 is manufactured. The foamed tube 2 coming out of the foaming mold 42 is sent to the foam layer forming process unit 33 by the first take-up machine 43.
[0116]
In the pipe feeding process part 32 a, the pipe 11 is fed from the feeding machine 51 by the second take-up machine 52, and sent out to the foam layer forming process part 33 while curling flaws are corrected by the curl correction device 53.
[0117]
The foamed tube 2 sent to the foam layer forming process unit 33 by the first take-up machine 43 is continuously cut in the extrusion direction (longitudinal direction of the tube) by the cutter blade 61a of the cut forming device 61, The state shown in FIG. 3 is obtained.
[0118]
The foamed tube 2 is guided by a tapered surface formed on the upstream side in the conveying direction of the diameter-enlarged core 62a in the pipe insertion device 62, and the foamed tube 2 is press-fitted into the diameter-enlarged core 62a to expand the diameter. In the bent part 62c of the diameter core 62a, the cut 21 of the foamed tube 2 is further widened, and the pipe 11 is inserted from the cut 21 into the insertion hole 62d of the diameter-expanded core 62a located inside the foamed tube 2.
[0119]
In this way, the foamed tube 2 that has been subjected to the foamed tube manufacturing process, the slit forming process, and the foamed tube diameter increasing process and the pipe 11 drawn out by the pipe feeding process are merged, and the pipe 11 is inserted into the foamed tube 2. First, the pipe 11 is sent out by the second take-up machine 52 and inserted into the enlarged core 62a from the notch.
[0120]
When the pipe 11 passes through the expanded core 62 a and the pipe 11 is inserted into the foamed tube 2, the expanded foamed tube 2 is reduced in diameter by the expanded foaming device 63. At this time, the foamed tube 2 is fed into the tapered tubular body 63a together with the pipe 11, and the foamed tube 2 is allowed to pass through the tubular body 63a, whereby the cut 21 of the foamed tube 2 widened by the expanded core 62a. The portion is easily closed, and the foamed tube 2 is reduced in diameter, resulting in the state shown in FIG.
[0121]
Next, the foamed tube 2 reduced in diameter with the pipe 11 inserted therein is introduced into a skin layer molding die 72 connected to the skin layer molding extruder 71, and is used for skin layer molding. While continuously passing the foamed tube 2 in which the pipe 11 is inserted into the passage of the mold 72, the melt resin for forming the skin layer is supplied from the skin layer forming extruder 71. As a result, the outer peripheral surface of the foamed tube 2 covering the outer periphery of the pipe 11 in the outer skin layer molding die 72 is further covered with the skin layer 13, and the coated pipe 1 shown in FIG. 5 is obtained.
[0122]
The coated pipe 1 coming out from the skin layer forming mold 72 is taken up by the third take-up machine 73 and taken up by a winder (not shown).
When the pipe is flexible, the coated pipe is wound up by a winder. When the pipe is not flexible, the coated pipe is cut into a certain length using a cutter.
[0123]
As described above, in the first embodiment, the foam layer 12 that covers the surface of the pipe 11 is not directly molded on the outer surface of the pipe 11, but only the foam tube 2 that becomes the foam layer 12 is manufactured, Since the pipe 11 is inserted into the pipe 11 and the pipe 11 is covered with the foamed tube 2, the foam layer 12 which is uniformly highly foamed is obtained. Furthermore, a series of processes for manufacturing the coated pipe 1 can be performed in-line, and the coated pipe can be manufactured continuously, and cooling with the outer diameter regulating mold is rate-controlled as in the prior art, thereby increasing the production speed. Since the problem of not being present can be solved, the coated pipe 1 can be manufactured efficiently and inexpensively.
[0124]
In the first embodiment, the tapered tubular body 63a is used as the foaming tube diameter reducing device 63 in the foaming tube diameter reducing process, but the foaming tube diameter reducing process for reducing the diameter of the foamed tube 2 into which the pipe 11 is inserted is performed as described above. In addition to the tapered tubular body 63a of the first embodiment, the foamed tube 2 is configured by a pair of pressing bodies that press the cuts 21 of the expanded foamed tube 2 in the butting direction, and the foamed tube 2 is sandwiched between the pressing bodies. By doing so, the diameter of the foamed tube 2 may be reduced.
[0125]
For example, as another embodiment of the foam tube diameter reducing device 63 for reducing the diameter of the foam tube 2 into which the pipe 11 is inserted, as shown in the second embodiment in FIG. There is one using a pair of rotatable rollers 63b having an outer peripheral surface.
[0126]
The coated pipe manufacturing apparatus of the second embodiment for manufacturing the coated pipe shown in FIG. 12 is a modification of the specific configuration of the foamed tube diameter reducing device 63 which is the foamed tube diameter reducing process in the manufacturing apparatus of the first embodiment. In addition, a cut fusion process for fusing the cut 21 of the foam tube 2 between the foam tube diameter expansion process and the foam tube diameter reduction process is provided, and the other configuration is the first embodiment. The same reference numerals are used for the same reference numerals, and the description thereof is omitted.
[0127]
As shown in FIGS. 12 and 13, the foam tube diameter reducing device 63 of the second embodiment is composed of a pair of rotatable concave rollers 63 b having a tapered outer peripheral surface with a concave central portion in the axial direction. Yes.
[0128]
In the foam tube diameter reducing device 63 in the second embodiment, the expanded foam tube 2 is introduced between the two concave rollers 63b, and pressed in the direction in which the cuts 21 of the foam tube 2 are attached to each other by the concave rollers 63b. And the part of the cut line 21 of the foamed tube 2 expanded by the diameter-expanding core 62a is closed, and the diameter of the foamed tube 2 is reduced.
[0129]
Furthermore, as shown in FIG. 12 and FIG. 13, a cut fusing device 8 for fusing the cut 21 of the foamed tube 2 is provided on the upstream side of the concave roller 63b. It is comprised from the supply apparatus (not shown) and the hot air nozzle 81 used as a heating part. The cut fusion device 8 melts the surface layer resin of the cut 21 of the foamed tube 2 into which the pipe 11 has been inserted by hot air discharged from the hot air nozzle 81 and shrinks it with the two concave rollers 63 b of the foamed tube diameter reducing device 63. When making the diameter, the cut line 21 is fused, and the cross-section of the fused part can be in the state shown in FIG.
[0130]
Although not shown, the hot air supply device includes a fan and a heater. The hot air supply device can control the temperature of the hot air supplied to the hot air nozzle 81. The temperature of the hot air supplied to the hot air nozzle 81 is controlled by the resin of the foam layer 12. By controlling the melting point or higher, the skin resin of the cut 21 can be melted.
[0131]
The purpose of fusing the cut line 21 of the foamed tube 2 is to prevent the cut line 21 from opening in the skin layer forming step 34, and whether the fusing line 21 is fused at regular intervals or continuously. Can be selected accordingly. By controlling 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.
[0132]
The cut surface fusion process by the cut fusion device 8 is not limited to the above-described cut surface fusion by blowing hot air, but the cut 21 is directly brought into contact with a hot plate made of a heater and a metal plate, so that the surface resin of the cut 21 is obtained. May be melted.
[0133]
As described above, in the second embodiment, since the foam tube diameter reducing device 63 uses the pair of rotatable rollers 63b having a tapered outer peripheral surface having a concave in the center in the axial direction, the expanded foam tube 2 having a diameter increased. Can be easily reduced in diameter, and the melted cut 21 can be easily fused. Moreover, since the diameter reduction operation of the foamed tube 2 by the concave roller 63b can be performed without applying tension to the foamed tube 2, only the foamed tube 2 is prevented from contracting when the coated pipe is cut. The product dimensions can be stabilized.
[0134]
Moreover, in 2nd Embodiment, as a structure which has the cut | fusion fusion process which fuse | melts the opposing surfaces of the cut | disconnection 21 of the foamed tube 2 diameter-reduced after a foam tube diameter reduction process and before a skin layer formation process. Therefore, the cut line 21 can be fused before the skin layer 13 is formed, and it is possible to reliably prevent the cut 21 part from opening during the formation of the skin layer 13 and to prevent deterioration in quality. .
[0135]
Moreover, since the surface fusion resin in the portion of the cut 21 of the foamed tube 2 is melted by hot air blown from the hot air nozzle 81 and the opposing surfaces of the cut 21 are fused, the cut fusion process is simple. The cut 21 can be fused without causing the foam tube 2 to lose its shape by directly contacting the heat source by the method.
[0136]
In the first embodiment, the foam tube supply process is configured by the foam tube manufacturing process section 31a, and in the foam tube diameter reducing process, the tapered tubular body 63a is used as the foam tube diameter reducing device 63, but FIG. As shown in the third embodiment, the foamed tube 2 is prepared in a separate process in advance and wound around the reel 47, and the foamed tube 2 is drawn out from the reel 47 and is foamed by the first take-up machine 43 in the foam layer forming process section 33. In the same manner as in the second embodiment described above, the cut tube fusion process by the hot air nozzle 81 and the foaming by the foaming tube diameter reducing device 63 comprising the two concave rollers 63b are provided. A tube diameter reducing step may be provided.
[0137]
Further, in the first embodiment, in order to fit the foamed tube 2 to the pipe 11, a pipe feeding process part 32 a is provided, and the pipe 11 manufactured in advance from the feeding machine 51 is fed to reach the pipe insertion process. However, as in the fourth embodiment shown in FIG. 16, the pipe molding extruder 54 in which the thermoplastic resin composition for forming the pipe 11 is melt-kneaded, and the pipe molding extruder 54 are extruded. In addition, a pipe manufacturing process section 32b having a mold 55 for molding the pipe 11 and a second take-up machine 52 for receiving the pipe 11 coming out of the mold 55 is provided. As in the second embodiment, a cut fusion process by the hot air nozzle 81 and a foam tube diameter reducing process by the foam tube diameter reducing device 63 including the two concave rollers 63b are provided. It may be so that.
[0138]
【Example】
EXAMPLES Hereinafter, the present invention will be specifically described by way of examples. However, the present examples are illustrative and do not limit the present invention.
Example 1
In Example 1, the manufacturing apparatus in the second embodiment (FIG. 12) described above was used. A mixture of 100 parts by weight of low-density polyethylene (manufactured by Nippon Polychem; product number “LF440HB”) and 3 parts by weight of talc (manufactured by Sumika Color; product number “SS-11-20”) The raw material hopper 41a was supplied and melted by heating with a foam tube forming 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 41 b of the foaming tube forming extruder 41.
[0139]
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, and the resin extrusion rate of the foaming tube molding extruder 41 is 0.2 kg / h. The mixture was controlled so as to be, and kneaded at 120 ° C. in an extruder 41 for forming a foamed tube. The temperature of the foaming mold 42 was set to 108 ° C., and the pressure was released to the atmospheric pressure from the outlet having an inner diameter of 3 mm and an outer diameter of 6 mm to obtain a uniform foamed tube 2 having an inner diameter of 18 mm, an outer diameter of 24 mm, and an expansion ratio of about 6 times.
[0140]
Next, the foam tube 2 was taken up by the first take-up machine 43 and sent to the cut forming device 61 through the guide roller 47, and the cut 21 was continuously made in the extrusion direction by the long cutter blade 61a in the foam tube 2. . Subsequently, the foamed 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.
[0141]
On the other hand, a cross-linked polyethylene pipe having an outer diameter of 17 mm as the pipe 11 is fed from the feeding machine 51 by the second take-up machine 52 at a speed of 3 m / min, inserted into the inside of the expanded core 62a, and the pipe covered with the foam tube 11 was obtained. Subsequently, the center of the axial direction was expanded by the expanded core 62a by pressing in the abutting direction the cut of the expanded foam tube 2 by the pair of rotatable concave rollers 63b having a concave shape in a tapered shape. The cut 21 was closed, and the pipe 11 was continuously inserted into the flow path of the skin layer molding die 72 connected to the skin layer molding extruder 71. In Example 1, the cut was not fused.
[0142]
On the other hand, a mixture of 100 parts by weight of low-density polyethylene (manufactured by Nippon Polychem; product number “LF440HB”) and 5 parts by weight of pigment masterbatch (manufactured by Toyo Ink; product number “TET3MA1070RG”) is extruded from the raw material hopper 71a to form a skin layer. It was supplied to the machine 71 and melt-kneaded at 170 ° C. Subsequently, the skin layer forming resin is led out from the skin layer forming extruder 71 to the resin supply path of the skin layer forming die 72, and the skin layer 13 is 200 μm on the outer periphery of the pipe 11 covered with the foamed tube 2. The coated pipe 1 covered with the thickness was taken up by the third take-up machine 73 and taken up by the winder.
[0143]
(Example 2)
Before introducing the pipe 11 covered with the foamed tube 2 into the foamed tube diameter reducing device 63, a cut fusion process is provided, the heater temperature of the hot air supply device is set to 200 ° C., and the surface layer of the cut 21 is passed through the hot air nozzle 81. After the resin was continuously melted, a coated pipe was manufactured in the same manner as in Example 1 except that the resin was introduced into the foam tube diameter reducing device 63 and the cuts 21 were continuously fused.
In Example 2, since the cut line 21 was continuously fused, it was possible to reliably prevent the cut line 21 from separating when the skin layer 13 was formed.
[0144]
(Example 3)
Example: The fan of the hot air supply device was turned on and off every 10 seconds to melt the cut 21 intermittently, and then introduced into the foam tube diameter reducing device 63 to intermittently fuse the cut 21. A coated pipe was produced in the same manner as described above.
In Example 3, the cut line 21 was intermittently fused, but it was possible to reliably prevent the cut line 21 from separating when the skin layer 13 was formed.
[0145]
Example 4
In Example 4, the manufacturing apparatus in the third embodiment (FIG. 15) described above was used. The foamed tube 2 was previously wound on a reel or the like, and as shown in FIG. 15, these were unwound and the foamed tube 2 was sent to the foam layer forming process section 33 by a take-up machine, as in Example 1. A coated pipe was manufactured.
Since the foamed tube 2 produced in advance and wound on a reel or the like is used, the heat generated when the cut 21 is formed can be reduced as compared with the case where the foamed tube 2 is produced in-line, and the cut is formed. I was able to increase the line speed.
[0146]
(Example 5)
In Example 5, the manufacturing apparatus in the above-described fourth embodiment (FIG. 16) 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, and the foam layer forming step is continuously performed by the second take-up machine 52 without feeding the preformed pipe. A coated pipe was manufactured in the same manner as in Example 1 except that it was sent to the section 33.
Since the pipe 11 and the foamed tube 2 can be performed in-line, the manufacturing cost can be reduced.
[0147]
(Comparative Example 1)
A crosshead die was connected to the foaming extruder used in Example 1, and a long land die having a length of 170 mm (10 times the outer diameter of the pipe) was further connected to the crosshead die. An extruder for layer resin extrusion was connected, and a tank, a pump, and a conduit were connected so that a lubricant could be supplied to the inlet of the long land die.
Resin composition pre-weighed and pre-blended to 100 parts by weight of low density polyethylene and 1.5 parts by weight of P-P'-oxybis- (benzenesulfonylhydrazide) in low density polyethylene in the hopper of the foaming extruder used in Example 1 The product was fed and extrusion started. At this time, the gas supply port was not used with a blind plug.
At the same time, a resin composition pre-weighed so that carbon black was 20 parts by weight with respect to 100 parts by weight of high density polyethylene was supplied to an extrusion hopper for extruding the skin layer resin, and extrusion was started. At this time, a cross-linked high-density polyethylene pipe having an outer diameter of 17 mm was supplied to the crosshead die using the pipe feeder used in Example 1. Further, foam cooling was performed in the long land die using a long land die, and a foam layer and a skin layer were simultaneously formed on the outer periphery of the pipe at the outlet of the long land die. At this time, a lubricant polyoxymethylene-polyoxypropylene copolymer was supplied to the long land die inlet.
[0148]
The thickness of the foam layer of the coated pipe obtained as described above was 3 mm, and the thickness of the skin layer was 0.2 mm. As a result, only a coated pipe having an expansion ratio of about 2 was obtained.
[0149]
Furthermore, the contraction state of the foamed tube 2 was compared between the case where the enlarged core 62a shown in FIGS. 6 and 7 was used and the case where the enlarged core 62a shown in FIG. 8 was used. When the diameter-expanded core 62a shown in FIGS. 6 and 7 is used, the shrinkage at the cut end when the coated pipe is cut after the coated pipe is formed with respect to the tube length (1000 mm) of the foamed tube immediately before the cut is formed. Whereas the dimension was 15 mm, when the diameter-expanded core 62a shown in FIG. 8 was used, the coated pipe after forming the coated pipe was cut with respect to the tube length (1000 mm) of the foamed tube immediately before the cut formation. The shrinkage dimension at the cut end was 1 mm.
[0150]
From the above results, as shown in FIG. 8, the expansion due to frictional heat of the foamed tube 2 can be reduced by forming the concave portion 62 g for reducing the contact area with the inner surface of the foamed tube 2 in the expanded core 62 a. The shrinkage | contraction of the foaming tube 2 after covering pipe formation was able to be suppressed.
[0151]
【The invention's effect】
As described above, according to the coated pipe of the present invention, the foam layer is formed in a cylindrical shape, and a cut extending in the longitudinal direction for inserting the pipe into the cylinder is formed in the cylindrical foam layer. Since a continuous skin layer is formed on the outer periphery of the foam layer having a cut line, an end portion in the axial direction of the coated pipe, such as a connecting operation between the coated pipes, can be obtained while obtaining a uniformly highly foamed foam layer. In the case where the foam layer must be removed from the pipe, the foam layer can be easily peeled off from the cut portion, so that the connecting operation of the coated pipe is also facilitated.
[0152]
Furthermore, according to the manufacturing method and the manufacturing apparatus of the present invention, the outer periphery of the pipe can be uniformly coated with a foam layer that is highly foamed, and the outer periphery of the coated pipe is efficiently coated. Can be manufactured inexpensively.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram of a manufacturing apparatus for manufacturing a coated pipe according to a first embodiment of the present invention.
FIG. 2 is a cross-sectional view of a foamed tube manufactured in a foamed tube manufacturing process in the method for manufacturing a coated pipe of the present invention.
FIG. 3 is a cross-sectional view of a foamed tube in which a cut is formed in the slit forming step in the method for manufacturing a coated pipe of the present invention.
FIG. 4 is a cross-sectional view of a pipe in a state where a foam layer is formed on the outer periphery of the pipe through a diameter reduction step after the pipe is inserted into the foam tube in the pipe insertion step in the method for manufacturing a coated pipe of the present invention. is there.
FIG. 5 is a cross-sectional view of a coated pipe manufactured by the method for manufacturing a coated pipe of the present invention.
FIG. 6 is a perspective view showing a cut forming device and a diameter expanding core of a pipe inserting device in a manufacturing apparatus for manufacturing a coated pipe.
FIG. 7 is a perspective view showing another embodiment of a cut forming device in a manufacturing apparatus for manufacturing a coated pipe and a diameter-expanding core of the pipe insertion device.
FIG. 8 is a perspective view showing another embodiment of a diameter-expanding core of a pipe insertion device in a production apparatus for producing a coated pipe.
9 is a cross-sectional view taken along line XX in FIG.
FIG. 10 is a perspective view showing another embodiment (a linear diameter-expanding core) of a diameter-expanding core of a pipe insertion device in a manufacturing apparatus for manufacturing a coated 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 coated pipe (a foamed tube and a pipe are fitted together while being bent with a bent-type diameter-expanding core); It is.
FIG. 12 is an overall configuration diagram of a manufacturing apparatus for manufacturing a coated pipe according to a second embodiment of the present invention.
FIG. 13 shows a cross-sectional view of a concave roller and a schematic diagram of a hot air nozzle of a foam tube diameter reducing device used in a manufacturing apparatus according to a second embodiment.
FIG. 14 shows a method of manufacturing a coated 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 after a diameter reduction step after the pipe is inserted into the foam tube in the pipe insertion step. It is pipe sectional drawing of the state with which it was worn.
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 is an overall configuration diagram of a manufacturing apparatus for manufacturing a coated pipe according to a fourth embodiment of the present invention.
[Explanation of symbols]
1 Coated pipe
11 Pipe
12 Foam layer
13 Skin layer
2 Foam tube
21 Break
31a Foamed tube manufacturing process department
41 Extruder for forming foamed tubes
42 Foam mold
61a, 61i cutter blade
62a Expanded core
63a Tubular body
71 Extruder for skin layer molding
72 Mold for skin layer molding

Claims (17)

A method for producing a coated pipe in which a foam layer is formed on a pipe surface, and a skin layer is formed on the outer periphery of the foam layer
A slit forming step that continuously cuts the foam tube that becomes the foam layer while continuously feeding in the longitudinal direction,
A pipe insertion step of inserting the pipe into the foam tube from the cut while expanding the diameter of the foam tube having the cut;
A foam tube diameter reducing step for reducing the diameter of the foam tube into which the pipe is inserted;
A method for producing a coated pipe, comprising: a skin layer forming step of forming a skin layer on an outer periphery of a foamed tube having a reduced diameter by inserting a pipe. The method for manufacturing a coated pipe according to claim 1 , wherein the slit forming step includes a foam tube manufacturing step of extruding the foam tube for continuously supplying the foam tube. The foaming tube manufacturing step is characterized in that the molten resin mixed with a physical foaming agent is sent from the foaming tube molding extruder to the foaming mold in a decompressed state and is released from the foaming mold to atmospheric pressure. Item 3. A method for producing a coated pipe according to Item 2 . The method for producing a coated pipe according to claim 3 , wherein the physical foaming agent is carbon dioxide gas. The method for producing a coated pipe according to any one of claims 2 to 4 , wherein a foaming ratio of the foamed tube formed by extrusion foaming in the foamed tube production process is 5 times or more. The slit forming step is performed by rotationally driving a rotatable circular cutter in the same direction as the advancing direction of the foamed tube, and manufacturing the coated pipe according to any one of claims 1 to 5. Method. In the pipe insertion process, the foamed tube is introduced into a diameter-expanding core having a taper that is tapered on the upstream side in the feed direction of the foamed tube, and the diameter of the foamed tube is increased while the foamed tube is being conveyed. The method of manufacturing a coated pipe according to any one of claims 1 to 6 , wherein the pipe is inserted from a slit opened in the foamed tube. The method of manufacturing a coated pipe according to any one of claims 1 to 7 , wherein the pipe insertion step includes a cooling step of cooling the expanded foam tube. In the foam tube diameter reduction process, the foam tube into which the pipe is inserted is fed into the cylindrical body whose downstream side in the feed direction of the foam tube is tapered, and the cut portion of the foam tube is joined to reduce the diameter of the foam tube. The manufacturing method of the covering pipe in any one of Claims 1-8 characterized by the above-mentioned. In the foam tube diameter reduction process, a pair of rotatable rollers having a tapered outer peripheral surface with a recessed central portion in the axial direction is used, and a foam tube expanded in diameter is introduced between two rollers. The method for manufacturing a coated pipe according to any one of claims 1 to 8 , wherein the foamed tube is reduced in diameter by pressing in a direction in which the opposing surfaces of the cut of the foamed tube are attached. 11. The process according to claim 3, further comprising: a cut fusion process for fusing the opposing surfaces of the cuts of the reduced diameter foam tube after the foam tube shrinking process and before the skin layer forming process. The manufacturing method of the covering pipe in any one of. The method for producing a coated pipe according to claim 11 , wherein in the cut fusion step, the surface layer resin at the cut portion of the foamed tube is melted with hot air to fuse the opposing surfaces of the cut. In the skin layer forming step, the foamed tube, into which the pipe has been inserted, is sent to the skin layer forming mold, and the skin layer forming resin melted from the skin layer forming extruder is sent to the skin layer forming mold. The method for producing a coated pipe according to any one of claims 1 to 12 , wherein a skin layer is formed on the outer periphery of the foamed tube by extrusion. An apparatus for manufacturing a coated pipe in which a foam layer is formed on a pipe surface, and a skin layer is formed on the outer periphery of the foam layer
A slit forming process unit that continuously feeds the foam tube to be the foam layer while continuously cutting the foam tube in the longitudinal direction of the tube,
A pipe insertion process part for inserting a pipe into the foamed tube from the cut while expanding the diameter of the foamed tube with the cut;
A foam tube diameter reducing step for reducing the diameter of the foam tube into which the pipe is inserted;
An apparatus for producing a coated pipe, comprising: a skin layer forming step for forming a skin layer on an outer periphery of a foamed tube into which a pipe is inserted and reduced in diameter. 15. The apparatus for manufacturing a coated pipe according to claim 14 , wherein the slit forming step section includes a rotatable circular cutter and a cooling facility for the circular cutter. The pipe insertion process part has a taper that is tapered toward the upstream side of the foam tube feed direction, and has a diameter-expanding core that expands the diameter of the foamed tube. The coated pipe according to claim 14 or 15 , further comprising a guide recess for inserting the pipe into the foamed tube from a cut of the foamed tube widened by expanding the diameter, wherein the guide pipe is provided with a contact recess. Manufacturing equipment. Pipe insertion step portion, the manufacturing apparatus of the coating pipe according to claim 16, further comprising a cooling mechanism for cooling the foam tube is expanded from claim 14, characterized.

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