JPH0939064A - Method for manufacturing heat-insulating material covered tube with protective sheet - Google Patents

Abstract

(57) [Summary] SOLUTION: A resin die in which a fiber 2 serving as a heat insulating material is supplied into a heat insulating material die 3 to cover the outer circumference of the inner pipe 7, and the outer circumference of the fiber 2 is joined to the heat insulating material die 3. The outer circumference of the inner tube 7 is covered with the resin layer 6a formed via the resin layer 6a. After that, the inner tube 7 whose outer periphery is covered with the fiber 2 and the resin layer 6a is cooled and sized. [Effect] Insulation material with a protective sheet that has good outer diameter dimensional accuracy while preventing fluctuations in coating thickness due to uneven expansion of the fiber layer, sagging due to the weight of the fiber layer, and deformation due to cracking at the fiber confluence. Pipes continuously,
And it can be manufactured with inexpensive equipment.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a heat-insulating material-coated pipe having a heat-insulating material on the outer periphery of a tubular body and a protective sheet on the outer periphery of the heat-insulating material.

[0002]

2. Description of the Related Art For transporting heat medium such as hot water, steam, and cold water that needs to be insulated from the outside, a heat insulating material is coated on the outer periphery of the tubular body, and a protective sheet is further coated on the outer periphery of the heat insulating material. A heat insulating coating is adopted. And as a method of manufacturing this kind of heat insulation material covering pipe, for example, Japanese Patent Laid-Open No. 52-7
No. 061, JP-A-52-48153, or JP-A-53-66961 has been proposed.

Among them, the methods proposed in JP-A-52-7061 and JP-A-52-48153 use a foaming resin as a heat insulating material. First, the foaming resin is formed on the outer circumference of the inner tube. This is a method of forming a layer and then coating the outer periphery of the foamable resin layer with a thermoplastic resin.

Further, the method proposed in Japanese Patent Laid-Open No. 53-66961 uses fiber or powder as a heat insulating material, runs an inner tube at the center of a hollow heat insulating material extruding screw, and makes the outer circumference of this inner tube. In this method, the fiber or powder is coated and then sized, and then the outer periphery of the sized fiber or powder coating layer is coated with a thermoplastic resin.

[0005]

However, the above-mentioned conventional method has the following problems. First, in the methods proposed in JP-A-52-7061 and JP-A-52-48153, since a foaming resin is used as a heat insulating material, the heat insulating property is higher than that of fibers such as glass wool and rock wool. Is inferior. Further, since it is difficult to cool the inside of the resin after the resin is foamed, there is also a problem that the production speed must be reduced in order to perform sufficient cooling to prevent the deformation of the product.

Next, the method proposed in Japanese Patent Laid-Open No. 53-66961 uses fibers or powder as a heat insulating material, but since these are materials which are difficult to maintain their shape by themselves, they are sized. There is a problem that it is easy to expand or deform after leaving the part, and it is difficult to obtain a coating layer having a constant thickness. In addition, when the outer diameter of the inner pipe to be coated becomes large, the screw for pushing out the heat insulating material also has to be large, and the equipment cost becomes high.

The present invention has been made in view of the above-mentioned conventional problems, and manufactures a heat insulating material-covered pipe with a protective sheet which can solve the problems of moldability and equipment cost when fibers are used as a heat insulating material. It is intended to provide a way.

[0008]

In order to achieve the above-mentioned object, a method for producing a heat insulating material-covered pipe with a protective sheet according to the present invention is to supply a fiber as a heat insulating material into a heat insulating material die and The outer circumference is covered, and further, the outer circumference of the inner tube is covered with a resin layer formed on the outer circumference of the fiber through a resin die bonded to a heat insulating material die, and then cooling,
Sizing.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In the method for producing a heat insulating material-covered pipe with a protective sheet according to the present invention, first, a fiber serving as a heat insulating material is supplied to a heat insulating material die by using a heat insulating material screw, and the fiber is heated through the heat insulating material die. Guide the fiber to the outer circumference of the inner tube.
On the other hand, the resin die is supplied with a thermoplastic resin which is melted by a resin screw and serves as a protective sheet, and is joined to the surface of the fiber in the resin die to form a resin layer on the outer periphery of the fiber. Then, the heat insulating die and the resin die are coated with these in a state where a resin layer is formed on the outer circumference of the fiber on the outer circumference of the inner tube conveyed in a penetrating manner. Next, the inner tube, the fiber, and the resin layer are integrated and sent to the sizing / cooling zone to cool and solidify the resin layer.

As described above, in the method of the present invention, the resin layer is coated while the outer surface of the fiber layer is constrained in the resin die, and cooling and sizing are performed, so that the coating thickness varies due to the non-uniform expansion of the fiber layer. Also, it is possible to prevent the fiber layer from sagging due to its own weight and from being deformed due to cracking of the fiber joining portion.

In the method proposed in Japanese Patent Laid-Open No. 53-66961, a heat insulating material screw coaxial with the inner tube is used to eliminate the joint portion of the fiber layer to prevent cracking of the joint portion. However, since the fiber layer is once opened, it is not possible to prevent uneven expansion of the fiber layer and sag due to the weight of the fiber layer.

[0012]

EXAMPLES A method for manufacturing a heat insulating material-coated tube with a protective sheet according to the present invention will be described below with reference to an example shown in FIGS. FIG. 1 is an explanatory view of a method for manufacturing a heat insulating material-covered pipe with a protective sheet according to the present invention, and FIG.
(B) is also a view taken along the arrow BB, and (c) is also a view taken along the arrow C-.
FIGS. 3C and 3 are detailed explanatory diagrams of the sizing unit.

In the drawings, reference numeral 1 denotes a heat insulating material screw, which feeds a fiber 2 serving as a heat insulating material to a heat insulating material die 3. In this embodiment, as shown in FIG. 2, the gap in the heat insulating die 3 is devised so that the fibers 2 can be uniformly supplied in the circumferential direction in the heat insulating die 3.

Reference numeral 4 denotes a resin die provided on the downstream side of the heat insulating material die 3 so as to be continuous therewith, and the fiber 2 is guided to the resin die 4 through the heat insulating material die 3. On the other hand, to the resin die 4, the thermoplastic resin 6 which is supplied to the resin screw 5 and melted therein is guided,
The resin 2 is joined in the resin die 4 to form a resin layer 6a serving as a protective sheet on the outer periphery of the fiber 2.

Reference numeral 7 denotes an inner tube which is conveyed through the heat insulating material die 3 and the resin die 4 in a penetrating manner, and the outer periphery thereof is covered with the fiber 2 and the resin layer 6a in the above-mentioned state. Then, the inner tube 7 covered with the fiber 2 and the resin layer 6a
Is guided to the sizing / cooling zone 8 installed on the downstream side of the resin die 4, where the resin layer 6a is cooled and solidified.

That is, the fiber 2 and the resin layer 6a
The inner pipe 7 covered with is indirectly cooled by the copper pipe portion 8a with a spiral fin through which cooling water is passed around the outer periphery thereof, and then, while passing through the plurality of sizing plates 8b, the resin layer 6a is formed. It is directly cooled again by cooling water and solidified to form a heat insulating material-covered pipe with a protective sheet. In addition, 9 in FIG. 1 is a heat insulating material interposed between the resin die 4 and the sizing / cooling zone 8.

Next, the results of the actual production of the heat insulating material-coated tube with the protective sheet by the method of the present invention will be described.
Rockwool [JIS A9504] is supplied to a heat insulation screw with a caliber of 80 mm, L / D of 12, and tip groove depth of 25 mm. With this heat insulation screw, the inner diameter is 50 mm and the slit width is through a heat insulation die. Rockwool was extruded into a 2.2 mm resin die at 8000 cm ³ / min.

On the other hand, low density polyethylene [MFR = 0.3, density = 0.92] was fed to a resin screw having a diameter of 150 mm, L / D of 26, and a groove depth of 6 mm, and the resin screw was used to melt the low density polyethylene. And extruded into the resin die at a rate of 1.2 kg / min.

The outer diameter of the above resin die is 21.7 mm.
The steel pipe [JIS SGP 15A] was conveyed at 5 m / min, and the outer periphery thereof was coated with rock wool and low density polyethylene. Then, lead to the sizing / cooling zone (length of copper tube with spiral fin: 15 cm, length of sizing plate: 15 cm, cooling water temperature: 20 ° C.) having the configuration shown in FIG.
Here, the low density polyethylene layer was cooled and solidified. In addition,
The surface temperature of the low density polyethylene layer on the outlet side of the sizing / cooling zone was 50 ° C.

As described above, when the heat-insulating material-covered pipe with the protective sheet is continuously manufactured, the obtained product is
The total thickness of the coating layer was about 13 to 15 mm, the thickness of the protective sheet was 1.3 to 1.6 mm, and the thickness of the coating layer was almost constant. .

Although rock wool is used as the heat insulating material in the above-mentioned embodiments, glass wool, asbestos or the like may be used as long as it is a short fiber that can be supplied by extrusion. Although low-density polyethylene was used as the protective sheet, polypropylene, vinyl chloride or the like may be used as long as it is a thermoplastic resin having physical properties suitable for extrusion molding.

Further, as the constitution of the sizing / cooling zone, it is desirable to indirectly cool through a copper pipe portion as shown in FIG. 1 in order to prevent the cooling water from scattering in the resin die. It is possible to directly perform water cooling by using a sizing plate as shown in FIG. 1 or a copper tube having many holes.

In this embodiment, a tube having a circular cross section is coated one by one, but according to the method of the present invention, for example,
It is also possible to integrally extrude and coat the two inner tubes. It is also possible to coat a deformed tube such as a square tube.

Further, in the method of the present invention, when there is a possibility that the protective sheet may have penetrating flaws due to the condition of piping, a second layer of the protective sheet is extruded and coated after water cooling to provide excellent heat resistance. It is also possible to manufacture cladding. Further, in order to prevent the heat insulating material from sliding in the axial direction with respect to the inner pipe, it is possible to apply an adhesive in the previous step.

[0025]

As described above, according to the method of the present invention, the resin layer is coated in the resin die while the outer surface of the fiber layer is constrained, and cooling and sizing are performed. While preventing thickness fluctuations, sagging due to the weight of the fiber layer, and deformation due to cracks in the fiber confluence, it is possible to continuously and inexpensively install heat-insulating pipes with a protective sheet that have good outer diameter dimensional accuracy. Can be manufactured.

[Brief description of drawings]

FIG. 1 is an explanatory view of a method for manufacturing a heat insulating material-coated tube with a protective sheet according to the present invention.

2A is a view taken along the line AA of FIG. 1, FIG. 2B is a view taken along the line BB of FIG. 1, and FIG. 2C is a view taken along the line CC of FIG.

FIG. 3 is a detailed explanatory diagram of a sizing unit.

[Explanation of symbols]

 2 Fiber 3 Heat insulating material die 4 Resin die 6a Resin layer 7 Inner tube 8 Sizing and cooling zone

Claims (1)

[Claims] 1. A state in which a fiber serving as a heat insulating material is supplied into a heat insulating material die to cover the outer circumference of the inner tube, and a resin layer is formed on the outer circumference of the fiber through a resin die bonded to the heat insulating material die. A method for producing a heat-insulating material-covered pipe with a protective sheet, which comprises coating these on the outer circumference of an inner pipe, followed by cooling and sizing.