DE3490043T1 - Process for the production of a thermally insulating jacket or tube for one or more tubes - Google Patents

Description

TlEDTKE - BüHLING - KlNNE f * ÖftUPE; _: " _: -II-yJireteV'belmEPA p * r \ Ο" ·· * · ** · "· :. *. *" ^: - DTpC-lng. H. Tiedtke

Pellmann - Grams - otruiP "

Dipl.-Chem. G. Bühling

Dipl.-Ing. R. Kinne, Dipl.-Ing. R group

Dipl.-Ing. B. Pellmann O L QQQ !. 3 Dipl.-Ing. K. Grams

Dipl.-Chem. Dr. B. Struif

Bavariaring 4, Postfach 202403 8000 Munich 2

Tel .: 089-53 96 Telex: 5-24 845 tipat Telecopier: 0 89-537377 cable: Germaniapatent Munich

October 2, 1984 DE 4268 /. case FI830487 / TMA-

Neste Oy
Espoo /! Finland

Process for the production of a thermally insulating jacket or tube for one or more tubes.

The present invention relates to a method of manufacturing a pipe of insulating material which is a or has several inner tubes, a foam plastic insulation and a surface layer made of plastic, wherein at In this process, the foam is similar to the starting plastic material is passed to form the surface layer so that it encases the inner tube, and so on Foam plastic insulation and a surface layer are simultaneously created around the inner pipe in one step be, and with this method the surface layer in a calibration element to the desired size is cooled, the surface being pressed against the 'inner surface of this calibration element by means of a calibration pressure will.

Usually intermediate heating elements with two different Process made. In one of the two processes, the so-called internal foaming process,

Oresdner Bank (Munich) KIo 3939844 Deutsche Bank (Müncheni Kto 2861060 Postscheckamt (Munich) Kto 670- «3-80 *

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Next, a thin-walled PEH pipe is made. A steel tube is placed inside this tube by means of bearing supports attached. The space between the PEH pipe

and the steel pipe is then covered with urethane foam. filled. 5

In the other process, the so-called coating process, a steel pipe is placed in a mold in which urethane is foamed. In a separate In the first step, the foam is coated with polyethylene. With the help of this procedure, iso- * lationsröhren produced, wherein the foaming was carried out around a glass fiber reinforced polyester pipe. The foam is coated as described above. Here steel pipes or tubes of various sizes can be used

be inserted into the polyester pipe.

What these procedures have in common is that they have a large number of separate work steps with intermediate storage

exhibit. They are extraordinarily labor intensive and

difficult to automate. With both methods, bearings must be provided for the inner tube; through this the thermal conductivity can be increased. Additionally both procedures involve the use of

Uraethane foam in an unshielded room. 25th

In the prior art there is also a device at which is a plastic-coated pipe made of insulating material in a continuous extrusion process -can be. In addition to the surface layer

the inner tube can also be produced by extrusion ^ will; in connection with the extrusion process, the plastic cliaum is placed between the inner and the surface layers injected.

Finnish patent specification 34878 discloses a pre

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direction, in which the inner tube by means of an extrusion press in one step with a foam layer and a

r- plastic surface layer can be coated, b

The foaming nozzle of this device is arranged in such a way that it follows the nozzle for the surface layer, in such a way that the plastic foam insulation in the space between the surface layer and inner tube can be injected, specifically in the area between the nozzle head and the calibration element. The calibration element, preferably a vacuum calibration element, is at a distance from the nozzle for the Surface layer arranged so that the surface layer cool to a suitable calibration temperature 15th

can.

The disadvantages of the device according to Finnish patent application 54878 include the position of the Foaming nozzle in the direction of passage of the pipe so far behind the ·

Nozzle for the surface layer, whereby behind the Foaming nozzle a cavity is formed. If the air in the cavity is entrained with the foam, it becomes inside the surface layer directly behind the nozzle

Vacuum created. This makes the soft surface 25

layer drawn against the foaming nozzle; production comes to a standstill. The cavity can also be filled with hardened foam, creating a harmful influence exerted on the quality of the surface layer

will.
30th

Another disadvantage of the device according to the fin. Niche patent application 54878 is the arrangement of the Calibration elements at a distance from the nozzle for the surface layer. This makes the application of vacuum potassium 35

bration implies what is also in this patent specification is executed. However, the production is bigger

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Pipe dimensions (over 100mm) due to vacuum calibration are critical as the difficult task occurs, one to produce a tight seal between the tube and the calibration tube.

The invention is based on the object of improving the methods known in the prior art. In detail the invention is to provide a method in which the foaming and the production of the outer tube around the inner tube can be carried out simultaneously in one step and in which no vacuum calibration is necessary is. In addition, the method according to the invention should equally be used for a steel pipe and for a plastic pipe applicable.be.

According to the invention, this object is achieved by a method solved, which is characterized in its main in that the calibration pressure generated by the foaming is ·, the drop in calibration pressure is prevented by the plug that the foam in its Forms solidification.

The other distinguishing features of the invention Method are presented in claim 2.

The method according to the invention has many notable ones Benefits. For example, the invention enables a method for the production of intermediate heating elements, in which the foaming and the production of the outer layer can be carried out simultaneously in one step, and a steel or a polyester pipe. There is also no vacuum calibration in the method according to the invention necessary, as is still necessary in the case of the device of Finnish patent application 54878, for example was. The method according to the invention is the same

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well suited for an inner tube made of steel or plastic.

c As a foam material in the process according to the invention all foams are used which have the appropriate characteristics, for example heat resistance and Isolation ability have. A suitable foam material is, for example, polyurethane.

In the following the invention is based on an advantageous Embodiment described in more detail with reference to the drawing, the invention not based on this Execution example should be limited.

The figure shows an advantageous embodiment of the device used in the method according to the invention in longitudinal section.

In this embodiment, a device 10 ·

a tubular plastic nozzle 11 provided with a hollow mandrel,

a slide bearing 12 provided with centering capability for the Inner tube 17, a combined inner tube guide and foam nozzle body 13, an outer, water-cooled calibration tube 14, tubes 15 for foam feed and feed 25

channels 19 for the plastic starting material of the surface layer on. The method according to the invention makes the plastic surface layer 18 of the insulating tube and the foam plastic insulation 18 is produced.

In the method according to the invention, a foam plastic is used insulation 18 and a surface layer 16 formed simultaneously around the inner tube 17 in one work step. With the foaming, a calibration pressure is generated by the feed metering of the starting material and by the Temperature of the foam feedstock is controlled. External cooling 14 is used to

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the surface layer 16 in precise dimensions cool. As it solidifies, the foam forms a plug that prevents the calibration pressure from falling. The throughput speed, the foam components and the length of the calibration tube 14 must be such may be selected so that the foam is solidified and the element exits the calibration tube 14. Further Cooling and pulling elements can correspond to the conventional elements used in pipe manufacture; the same thing applies to the feed element for the inner tube 17.

The foam nozzle body 13 also serves as a guide element for

the inner tube 17. The nozzle body 13 is from the tube 15

nozzle 11 is insulated and can, if necessary, be water-cooled. A plurality of foaming nozzles can be installed in the nozzle body 13 be arranged to produce homogeneous foam; Pressure sensors can control the dosage. The foaming nozzles are arranged in such a way that the foam occupies the entire space between

of the surface layer 16 and the inner pipe 17 immediately behind the nozzle for the surface layer fills. The space between the interior 17 and the nozzle body 13 is sealed by conventional technology.

If necessary, a ventilation valve can be installed on the nozzle-25

body 13 sit, this valve is in the initial phase in operation. The nozzle body 13 can also be be designed to extend in the machine direction and in this way the inner surface of the

Protective layer 16 precooled. The calibration tube 14 is next to 30

the nozzle 11 arranged, which is necessary because of the pressure calibration technique.

The tubular nozzle 11 can with a conventional centering device and a spiral distributor or üqui-35

valenten devices known from the prior art. The plastic mixture can be through a

: 349 0-4

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or several extrusion presses are placed on this nozzle 11. To produce the protective layer 16 can also Extrusion processes are used.

The cross-sectional opening of the nozzle 11 and the calibration tube 14 do not have to be circular: an oval or other shape may be more advantageous, when two or more pipes are to be insulated.

By the present method, intermediate heating elements can be produced in one step. With Hxlfe the new type of pressure calibration can also large dimensions can be produced. The profile thickness

¹ ^ of the protective layer 16 can be precisely controlled; the outer surface of the protective layer 16 is smooth and corresponds exactly to the dimensions. The arrangement of the foaming nozzles in connection with the nozzle for the surface layer ensures that no cavities remain in the foam. The method also ensures good adhesion between the foam and the inner tube 17 and between the foam and the surface layer.

Claims (2)

Claims 1. Method of manufacturing a pipe from insulating material with one or more inner tubes (17), a plastic foam insulation (18) and a plastic surface layer (16), wherein in this method the foam material is passed in such a way that it creates the inner tube a foamed plastic insulation (18) encased, and in a similar way the plastic starting material to produce a surface layer (16) is passed, whereby around the inner tube (17) in one step simultaneously the foamed plastic insulation (18) and the Surface layer (16) is generated, and in this method the surface layer (16) in a calibration element (14) is cooled to a desired dimension, the surface layer (16) being counteracted by the calibration pressure the inner surface of the calibration element (14) is pressed, characterized in that the calibration pressure is generated by the foaming, the decrease in the calibration pressure is prevented by the plug that is generated by the foam when it solidifies. 2. The method according to claim 1, characterized in that the control of the calibration pressure by regulating the Foam feedstock supply and feedstock temperature is effected. r Rank (Mönchen) KIo 3939844 Deutsche Bank (Munich) Klo 2861060 i iMCincheni KIo 670-43-804