FR2536007A1 - PROCESS FOR THE PRODUCTION OF A HEAT INSULATING PIPING - Google Patents

Abstract

A.PROCESS FOR THE MANUFACTURE OF A HEAT INSULATING PIPE; B.PROCESS CHARACTERIZED BY THE COMBINATION OF THE FOLLOWING CHARACTERISTICS: USED AS TAPE 9 OF PLASTIC MATERIAL A SOFT TAPE, PREFERREDLY OF PLASTICIZED POLYVINYL CHLORIDE; -THE TAPE IS SHAPED SO THAT ITS EDGES ARE OVERLAPPED AND THESE EDGES ARE GLUED TOGETHER; -THE WALL THICKNESS OF STRIP 9 OF PLASTIC MATERIAL IS BETWEEN 0.08 AND 0.40MM; - THE METAL PIPE 2, WITH THE ORGAN 7 SPREADER AND THE STRIP OF PLASTIC MATERIAL 9 SHAPED INTO A TUBE AND GLUED TO ITS EDGES, IS MAINTAINED ON THE EXTERIOR DURING THE PERIOD OF FOAM FORMATION; -AND, AS A FOAM, A SOFT POLYURETHANE FOAM IS USED, WITH FIRM PORES; C. THE INVENTION APPLIES TO THE MANUFACTURE OF METAL TUBE, ESPECIALLY OF COPPER, THERMALLY PROTECTED.

Description

PROCESS FOR MANUFACTURING A PIPING

INSULATION OF HEAT

  The invention relates to a method for the manufacture of a thermally insulated pipe, in which, on a metal pipe, copper is preferably applied a helical winding intended to maintain a gap, it surrounds

  the metal pipe provided with this helical winding

  coldal, as it moves in the direction of its

  length of a plastic strip, preferably

  Polyvinyl chloride reinforcement, shapes this tube-shaped plastic strip and connects its edges, while applying to the strip of plastic material, before joining its edges, a mixture of plastics capable of forming a foam-based foam. polyurethane, which fills the annular space between the metal pipe and the strip of plastic, after the edges have been joined, A method of this kind is already known from DE-OS 19 However, this known method is suitable only for the manufacture of rigid thermally insulated pipes. The reason for this is that a plastic strip, itself rigid, is used as the outer casing. As this strip of material 25360 O Ot plastic constitutes at the same time the mold of the

  foam that forms, this band must be by itself

  even stable enough to contain the pressure that

  is established during the formation of the foam.

  For this reason, it was necessary to use a relatively thick polyvinyl chloride strip. This material was well suited to constitute the mold for the foam, and remained stable despite

  even the heat that emerges during the training

the foam.

  The object of the invention is to improve the known method by departing from the fact that it is possible to manufacture thermally insulated pipes that can be bent, that is to say pipes that can be to wind in crowns with a diameter of approximately 1 meter and that one can also pose, during the installation, in the curved state, that is to say

  without using tubular bends.

  This result is obtained by combining the following characteristics: a) using, as band

  of plastic material, a flexible band, preferably

  plasticized polyvinyl chloride; b) the strip is shaped so that its edges are superimposed and these edges are glued together; c) the thickness of the wall of the plastic strip is between 0.08 and 0.40 mm; d) the metal pipe with the spacer member and the plastic strip formed into a tube and glued on its edges is held on the outside in the foam-forming period;

2536 007

  e) and, as a foam, a uses flexible polyurethane foam, closed pores, it is further essential for the invention to use an annealed pipe We start here, either an annealed pipe which is in the form of crown, or again, it is annealed this pipe by operating continuously immediately before applying the element now the distance It is further essential that the metal pipe is

  introduced into the installation in the rectified state.

  Through the use of a strip of plastic material

  soft tick, it becomes easy to bend

  thermally insulated insulation without tearing the plastic strip The bonding of the overlapping edges ensures a solid connection between these edges

  which do not open even in case of curvature.

  Depending on the outer diameter of the foam layer, the wall thickness of the plastic strip will be between 0.08 and 0.40 mm. In the course of the formation of foam by the appropriate mixture, the relatively plastic material does not deform, the band formed in tube relative to the pipe will be maintained

  shaped from the outside until the operation -

  In contrast to what is known in the known processes, Iton uses, for reasons of insulation, a hard polyurethane foam, using a closed-cell polyurethane foam, flexible which even supports the ability of the pipe to bend, without the foam S crumbling or tearing during bending The tubular pipe, manufactured by the method according to the invention, can be wound without difficulty, that is to say without the outer shell is torn or the layer of foam deforms unacceptably, in crowns less than one meter in diameter, or placed in the curved state. According to an improvement of the invention, the bonding of the edges of the strip is effected by means of a solvent, or an adhesive in solution, in the form of, for example, cyclohexanone and / or tetrahydrofuran. These adhesives are shown the ones that best suited and

  the formation of a solid weld bead

  times it can be advantageous also to use

  a hot melt adhesive.

  The thus wrapped tube then passes into a calibrating device, for example a tube, a helical winding or a perforated plate, in which the relatively flexible plastic strip is clamped. The calibration device bore corresponds to the outside diameter of the pipe. thermally insulated finished, Due to the support from the outside, not only the stability of the form is obtained, but also the weld bead of the cover is stuck in an optimum way The pressure of the foam pressing

  the welding of the interior is absorbed by the

  Positive sizing, so that the superimposed edges of the band are tightly clamped on each other So that the friction forces, acting on the outer circumference of the pipe during the passage through the sizing tube or the helical winding, be kept as small as possible, the pipe, or the outer casing made of plastic material, is lubricated from the outside while passing through the calibration tube or the helical winding O As lubricant are suitable those which do not attack polyvinyl chloride, such as, for example, water, to which a slip agent, for example

  soap or even oils and similar substances

  guages. According to another advantageous design of the invention, the plastic band formed into a tube is surrounded, during the formation of the foam layer of a sheath.

  of external support, introducing itself longitudinally

  nally, pressed on its edges, in a mechanically strong material, paper, for example, and

  this holding sheath is eliminated from the

  completed, preferably after hardening

  This material, this paper for example, arrives, in the form of a strip, on the

  strip of plastic material in a long path

  dinal, the overlapping edges of the paper

  applied to form a tube being preferably

  together by means of an appropriate adhesive

  The section of the paper tube thus shaped into a tube corresponds to the outer diameter of the

  thermally insulated ducting Thanks to this

  On the one hand, on the one hand, the flexible plastic strip is protected against deformation, and on the other hand, it is obtained that the superimposing bead of the flexible plastic strip is completely bonded.

  due to the formation of foam on the

  hard layer is absorbed by the sheath

  out of paper, so that the edges super-

  laid of the plastic strip are strongly

tight against each other.

In the pursuit of

  tion of the process according to the invention, it has proved

253600 T

  advantageously placed between the holding sheath and the strip of flexible plastic material formed into a tube, a thread running along the length, made of textile, nylon for example By means of this thread, it is ensured the possibility of tear the retaining sheath, at the end of the manufacturing operation, in the direction of the axis of the tube This tear wire thus allows

  to easily remove the holding sheath previously

  This support sleeve may, however, remain on the pipe as protection during transport and be removed only at

the location of the assembly.

  The invention will be better understood with regard to the exemplary embodiments shown

  schematically in Figures 1 and 2.

  A ring 1 is drawn from a copper tube 2 drawn without welding and which is

  directed continuously by means of a set of ori-

  The pipe 2 is then passed through an annealing device 4, in which the copper pipe 2 is rendered ductile by annealing by means of a resistor. The annealed pipe 2 is then again oriented by means of another set of oriented rollers 5 This ductile copper pipe 2, thus prepared, is filled by a tangential winding 6 and held at a distance by a spiral 7, which may be made, for example of a cord of paper or a cord of foam Around the space of spiral material 7 intended to maintain the distance, a strip 9 of plastic material is wound which is drawn from a supply reel 8 and which is gradually shaped into a tube

  plastic strip is preferably made of

  plasticized polyvinyl chloride and has a wall thickness of approximately 0.2 mm Before closing

  the plastic strip 9 into a tube, it is sprayed

  on the plastic strip 9, by means of a spraying device 10, the plastic mixture which will form foam and which is usually composed of polyol and isocyanate. 1, an adhesive is applied to the edges of the shaped plastic strip 9 in the form of a tube 9,

  and strongly press these edges against each other.

  The assembly consisting of the strip of plastic material

  9 and the copper tube 2 held at a distance by the holding space 7, as well as the foam forming components which are in the annular space, is then introduced into a holding device 12, which can be, for example, for example, a calibration tube, a perforated plate or, as shown in the figure, a helical winding of elongated wire. The inner diameter of this

  helical winding of wire 12 corres-

  to the outside diameter of the pipe 13, thermally insulated, finished This winding 12 of wire must prevent the

  plastic material 9 deforms in an inadmissible manner

  under the influence of pressure, due to the

  For this reason, the axial length of the helical winding of wire 12 is chosen such that at the end of this winding,

  the foam forming operation is completed.

  As a foam, a closed-pored polyurethane foam is used which is set so as to be flexible enough that the thermally insulated pipe assembly 13 can be easily bent. During passage through the helical coil 12, on this pipe 3) I, from a wetting device 1 h 1, a lubricating agent, for example water with a slip agent This lubricant serves 6 ntiellement to reduce the friction between the strip of material 9 plastic and metal wire winding

  12, but it also serves as a source of heat.

  it is necessary during the operation of the formation of foam After the winding 12 of the metal, in the direction of the passage, a puller, chenille

  operates on line 13 thermal-

  This isolated Lr extractor is controlled in synchronism with the oriented roller sets 3 and 5. The finished thermally insulated pipe 13 is wound in a ring-shaped device 16 by means of a device 16.

and cut to the desired lengths.

Following the example of

  2, the assembly, consisting of the plastic strip 9 shaped in tube iorme and copper pipe 2, kept at a distance by the holding space 7, as well as the foam forming composites which are located in the annular space, is surrounded by a retaining sheath applied to the passage for this purpose, there is posed in the surrounding, a strip 18 of solid paper from a coil 17, which is shaped progressively in During this formation of a tube, a solid textile thread 19, coming from a spool 20, passes in the longitudinal direction of the pipe between the plastic strip 9 and the paper strip 18 The sheath 18, made of the strip of paper and used for holding, is stuck firmly to its edges by means of a gluing device

  21 The inside diameter of this sheath

  18 is the outer diameter of the

  pipe 13 thermally insulated and completed.

  This holding sheath 18 must prevent the plastic band 9 from deforming in an inadmissible manner under the effect of the pressure of the formation of foam. For this reason, the holding sheath 18 remains closed on the material band. Plastic 9 until the foam forming operation is completed As a foam, a closed-pored polyurethane foam is used, which is adjusted with such flexibility that the thermally insulated pipe 13 can be bent easily. in the direction of travel, a crawler extractor 15 exerts its action on the entire thermally insulated pipe, including the retaining sheath 18 This crawler extractor 15 is mounted in synchronism with the

  oriented rollers games 3 and 5 also oriented.

  After the crawler extractor 15, the holding sheath 18, previously applied, is cut by means of the tear wire 19 in the axial direction, torn off and eliminated in pieces 22. The thermally insulated pipe 13 is then wound into crowns by means of a device 16 and cut to the desired lengths. Using a copper pipe

  ductile rendering by annealing, polyurethane foam

  flexible thane, and a strip of plastic material 9 in plasticized polyvinyl chloride, it has been possible to manufacture a pre-insulated pipe which can be bent out of the workshop, the difficulties that arise during manufacture being solved

in an advantageous way.

Claims (6)

  1 Process for the manufacture of a thermally insulated pipe, in which, on a metal pipe (2), copper is preferably applied a helical winding (7) intended   to maintain a gap, one surrounds, the metal pipe   that (2) provided with this helical winding (12), while advancing in the direction of its length, a strip of plastic material (9) preferably   polyvinyl chloride, shapes this band of   a plastic tube-like mold and connects its edges, while applying to the plastic strip, before joining its edges, a mixture of plastics capable of forming a foam-based polyurethane foam, after which the the edges, the annular space between the metal pipe (2) and the strip of plastic material (9) characterized by the combination of the following characteristics: a) using as strip (9) - plastic material, a flexible band, preferably plasticized polyvinyl chloride; b) the strip is shaped so that its edges are superimposed and these edges are glued together; c) the thickness of the wall of the strip (9) of plastic material is between 0.08 and 0.40 mm; d) the metal pipe (2-) with the spacer member (,) and the strip of plastic material (9) shaped into a tube and glued to its edges, is held on the outside in the foam-forming period ; e) and, as a foam, we use   a soft polyurethane foam with closed pores. 2 Process according to the claim   cation 1, characterized in that the bonding of the plastic strip (9) is effected by means of a solvent or an adhesive in solution, based on   for example cyclohexanonre and / or tetrahydro- furan. 3 Process according to the claim   1, characterized in that the bonding of the edges of the strip (9) is carried out hot with what is calls a molten adhesive. 4 Process following one   any of claims 1 to 3, characterized   in that the pipe (2) passes into a -   calibration device which is in the form of a tube, perforated plates or a helical winding. Process according to any one   one of claims 1 to 4, characterized in that   that the pipe (2) is lubricated on the outside during its passage in the calibration device (3). 6 Process according to any one   one of claims 1 to 5, characterized in that   that the plastic web (9) formed into a tube is surrounded during formation of the foam layer with an outer holding sheath (12, made of a mechanically solid material   for example, applied by a lengthy introduction   dinal, the edges of which are glued together, this holding sheath being preferably removed from the   duct finished after the foam has hardened. 7 Process according to the claim   6, characterized in that a yarn (19) is introduced as a tear cord between the retaining sheath and the plastic strip.   shaped into a tube, in the axial direction.