FI57365C - VAERMEISOLERANDE MANTEL FOER ETT ROER ELLER EN SLANG - Google Patents

Description

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Patents »and the Board of Regents' 'Ansaksi' Exterior and Expenditure Public 30.0U. 80 (32) (33) (31) Pyydetty Utuelkuu »—Begird Priorlttt (71) Oy Fiskars Ab, Pojo, FI; 10600 Ekenäs, Suomi-Finland (Fl) (72) Jarl Theman, Tenala, Suomi-Finland (Fl) (7 * 0 Oy Kolster Ab (5 * 0 Heat insulating jacket for a pipe or hose) - Lempelöä eristävä vaippa putkea tai letkua varten BACKGROUND OF THE INVENTION The present invention relates to a heat-insulating jacket for tubing or tubing, which jacket is made of a thermoplastic mass of a thermoplastic or rubber material and a foaming agent and, if necessary, a bridge former which has been extruded and expanded by heating the mass above the foaming medium's decomposition temperature. brought to enclose the tube.

It is known to add thermoplastics and rubber mass foaming agents, which at elevated temperature decompose and emit gases, whereby the heated plastic mass expands to a porous mass of cell structure. This condition has also been utilized to, by extrusion through a nozzle of the desired cross-section, enclose a tube centrally inserted through the nozzle with an envelope of cellular plastic or cellular rubber.

Due to the fact that the mass extruded through the nozzle can freely expand after the nozzle during e.g. atmospheric pressure, this method obtains in its form quite indeterminate envelopes with undesirable dimensional variations and otherwise uneven quality. It has also not been possible to achieve the desired tight measurement tolerances of the casing by pressing or pulling after withdrawal from the extruder nozzle cooling and solidifying cellular plastic profile by a shaping calibration tool which, as known with success, is applied in extrusion and calibration. plastprofMer. The procedure requires Sven to make its own nozzle for each pipe and mantle size.

For example, Swedish laying-out document 6,813,801 and German laying-out letter 1 69 ** 130 It is previously known a method for manufacturing plates or geometrically simple cellular plastic articles, which mainly comprises two different steps. In the first step, in a thermoplastic material by kneading in an extruder, a foaming agent and bridging agent are mixed at a temperature lower than the decomposition temperature of said additive, after which the homogeneous mixture is extruded through a nozzle into a preformed Smne in the form of a thin plate. The obtained Smet is substantially compact and unsaturated, since neither foam formation nor bridge formation Snnu has occurred.

In the second step of the process, the preformed Smnet is passed, i.e. the preformed thin plate through a heating device which raises its temperature above the decomposition temperature of said additives, thereby foaming and bridging. The disc-shaped butter, which is heated on both sides to obtain sufficient iron and rapid temperature rise, is then allowed to expand freely into three dimensions and a cellular plastic plate or profile body is obtained to its dimensions in an unstressed shape.

With this method, only iron-thick plates and geometrically simpler profile bodies can be manufactured because the pre-formed Smnet S obtained after the process is disc-shaped. Of course, to produce a cylindrical sheath around a tube, the obtained foamed plates can be wound spirally around the tube, but the method is not suitable for such a more advantageous wrapping process, since the men are formed around the tube in its axial direction.

It is reasonably well known to those skilled in the art that one cannot apply the aforementioned German and Swedish method, that instead of extruding a preformed plate, a plastic tube with a compact and unprotected mass and then after a second step by external heating of the sheathed pipe bring the pulp to expansion and refinement. The reason for this failure simply lies in the fact that the mass expands in three dimensions, the diameter of the resulting foam sheath increasing and the foam sheath no longer seated to the tube, but forming an undefined foam mass around the tube, which should be fed at a constant rate. speed while the expanding men constantly strive to increase their linear velocity as a result of the three-dimensional 1a expansion. In addition, no heating of the non-expanded pulp for its foaming cannot be carried out inside due to e.g. the presence of the pipe, which is not exposed to harmful thermal effects because the pipe consists of heat-sensitive material.

The present invention is intended to provide a heat insulating jacket for a tube, which jacket can be manufactured in a simple set with precise desired melt tolerances and with uniform cellular structure throughout. The casing of the pipe can be manufactured Sven with thick dimensions and without the need for extra extruding nozzles and 3 57365 o in thick preforms.

This is thus achieved with a jacket according to the invention, characterized in that the male ends are made up of a number of longitudinal strands of said mass, which strings are adhered to each other by means of heating, expansion and grouping around the tube and forming a coherent casing. around the tube.

By means of the embodiment according to the invention, men can be made up of a larger or smaller number of similar strands, which are separately expanded under similar conditions, whereby a fine and evenly uniform cellular structure is obtained regardless of the thickness of the mantle. This is due to the fact that the strings can be heated evenly from all directions and that the strings can be given a possible symmetrical cross-section, which allows even and rapid heat absorption.

By performing men's coins of preformed strings instead of a single deformed disc, one can, according to the building block principle, be built up into large jackets of a number of strings adjacent to one another. One can thereby make preformed strings in layers with a large capacity and with a single strand dimension one can then manufacture sheaths in different dimensions, thus making it possible with a single extruder.

The special construction of the casing of the pipe also makes it possible to continuously re-coat pipes and hoses of heat-sensitive material without the material having to be subjected to a harmful heating.

In addition, the desired shape of the final men can be achieved precisely by means of external shaping without giving the men a hard compact surface layer and without subjecting the men to frictional forces.

The invention will be described in greater detail in the following with reference to the accompanying drawings, in which Fig. 1 shows schematically an advantageous method for manufacturing a sheathed pipe according to the invention, and Figs. 2, 3 and k show cross sections along lines 11-11, Ill. III and IV-IV in Figure 1.

The method shown in Fig. 1 consists of preformed strands 1 of substantially compact undegradable plastic or rubber material, preferably the polyethylene or other polyolefin, containing a suitable amount of a foaming agent, e.g. azodicarbonamide or at the same time a foaming agent as a bridging agent, e.g. a suitable organic peroxide, such as dicumyl peroxide. All substances preferably have a possible symmetrical cross section and the same cross section profile1 - round or angular.

The strings 1 are passed in separate paths without mutual contact with each other through their heating device 2, where the strands are heated by hot air, infrared radiation, microwaves or other suitable heating technology. By this heating to the decomposition temperature of the foaming agent and the brewing agent, the strands begin to expand during simultaneous cross-linking of the molecules. It is often an advantage if the surface layer of the strands is first heated rapidly, so that partial bridging? the surface layer enters, before the core begins sub-gS expansion and bridging. Thereby, a stronger surface layer is obtained, which facilitates the joining of the relatively soft and partially plastic expanding strands.

When the strands are reached in the near full expansion and bridging, the sticky strands are brought together for mutual contact in a predetermined geometric pattern, which in most men corresponds to the profile one wishes to obtain. The strings are evenly arranged around a continuously advancing tube 3, whose insulating sheath the strings are intended to form. The strings are joined by inserting them together in a form in the order A in Moving in the production direction A at a constant speed adapted to the volume of the input string.

The shaping device consists of two interconnected endless conveyor belts or chains 5, pS which are mounted pre-assembled shaping blocks 6, which in pairs enclose and form the strand, which here still possesses sufficient expansion s to fill the mold space to the desired fu .

Upon entry into the shaping device, the expansion is mechanically inhibited axially, i.e. in the production direction, because the bundle forming members, which move at a constant speed, prevent any further increase in speed of the string bundle in the axial direction. Tili, as a result of the thus hindered axial expansion, instead increases the radial expansion to a desirable extent to better fill all the mold cavities and veneers.

In the mold space 7 bounded by the molding blocks 6, the sticky strands are welded to each other due to the deforming pressure resulting from the material expansion of the material and the compressive action of the molding elements. It is advantageous to arrange the possibility of heating and / or cooling the design elements if necessary.

No damaging frictional forces between the product and the shaping surfaces of the shaping device do not exist. The D5 strands are fully or partially heated to a plastic state during shaping, in addition to the molding contemplated by the swelling against the mold surfaces, a further mechanical, thermoplastic normal hot molding can proceed through the pressure of the molding surfaces against the moldable plastics material.

It will be seen that the casing 8 of the fabricated sheathed tube 3 is made up of a plurality of adherent strand-shaped cellular plastics.

5 S 73 6 S

elements which exhibit a uniform cell structure in that their heating in and for foaming and bridging can be carried out separately from each other in a heating point of view advantageous smaller strands. This way of constructing the tube mantle of separate strands thus makes it possible to manufacture different Large and different thick mantles merely by adjusting the number of strands to the cross section of the manhole and using a single strand dimension.

It is convenient to manufacture the aforementioned preformed strands 1 by mixing the plastic or rubber material 1 with the foaming agent and optionally a brewing agent by kneading in an extruder at a temperature lower than the decomposition temperature of the batches. The so-obtained homogeneous mass is extruded through a multi-ply nozzle to form said preformed strings 1, which are preferably wound into rollers for storage in storage.

Instead of manufacturing the strands by extrusion, strings suitable for the process according to Fig. 1 can also be obtained by cutting streams from a plate which is operated in a manner known per se of said pulp by extrusion in disk form.

The drawings and the accompanying description portion are intended only to illustrate the idea of the invention. Tili sinä details, the sheathed pipe can vary considerably within the scope of the claims. In other words, it is e.g. It is possible to build men's strings of several strings joined together.

Claims (3)

6 57365 1. Heat-insulating tube or tubing mantle, which jacket (8) is made of a thermoplastic mass of a thermoplastic or rubber material and a foaming agent and, if necessary, also a bridge former, the mass of which is extruded and expanded by heating the mass. The decomposition temperature of the foaming agent and caused to enclose the tube, characterized in that the manifold (8) consists of a number of tubes (1) of the said mass (1) of said tubes extending tubes, which are swirled by means of tubes (3). extend to each other and form a cohesive casing around the tube. 2. A mantle according to claim 1, characterized in that the strands (1) are formed of extruded preforms, 1111 initially non-expanded smears which, in connection with the grouping around the tube (3) and a residual expansion, are subjected to an outer molding (6) to elongate the strands. for tSt application to each other and the pipe. 3. A jacket according to claim 2, characterized in that the preformed non-expanded smears (1) have a symmetrical cross section.