FI58885C - FOERFARINGSSAETT FOER FRAMSTAELLNING AV LAONGSTRAECKTA HAOLKROPPAR AV SKUMPLAST ELLER LIKNANDE MATERIAL - Google Patents

Description

RSFn M (11) ANNOUNCEMENT c QOO Ci ÄjÄ l J '} UTLÄCGNINOSSKIUFT Ο Ο O 0 0 C (45) Patent granted 11 05 1931 Patent me <Helat v— (51) Kv.ik.Wa.3 B 29 D 27 / 00, 23/10 FINLAND —FINLAND (21) PtMnttlh * k * inu * -P «t« nt ^ kninj 1263/71 *

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_. (44) Date of publication of the decision. -

Patent-och registerttyrelaen AntOkan utl ^ d och uti. * Krtft «n pubtiund 30.01.81 (32) (33) (31) Pyydetty etuelkey * - B« (ird priority 29.05.73

Sweden-Sverige (SE) 7307598-8 (71) Rockwool Aktiebolaget, Skövde, Sweden-Sverige (SE) (72) Willy Hartung, Skövde, Sweden-Sverige (SE) (7U) Berggren Oy Ab (5U) Method for elongated hollow bodies The present invention relates to a process for the production of elongate hollow bodies, in particular for tubular bowls or ventilation ducts, from a foamable, hardenable, or hardenable, hardenable or hardenable material. These hollow bodies are also used, for example, as thermal insulation for pipelines of hot or cold substances. In order for these elongate hollow bodies to be so versatile, they are required to have good thermal insulation on the one hand and relatively good mechanical strength on the other. In addition, they must be able to be manufactured at an economically reasonable cost.

It has already been proposed to make tubular bowls in the shape of elongate hollow bodies from mineral wool. Although such tube bowls can be made mechanically strong to the point where they can also be used as ventilation ducts, if this is desired, the economic difficulties are encountered in that the tube bowls have to be made very tight and thus contain a large amount of mineral wool. At the same time, their thermal insulation would deteriorate significantly due to the increased tightness.

The present invention therefore starts from the fact that such elongate foam or similar shaped bodies must be made of a material having a high thermal insulation capacity and which, in the state in which it has this high thermal insulation capacity, also has satisfactory mechanical strength and rigidity. In addition, the raw material used must be cheap, and finally, the hollow body must be able to be manufactured at the factory with relatively simple equipment, so that the manufacture itself does not become expensive either.

One already known material which meets the said requirements is a self-foaming plastic, such as polyurethane plastic, which, when the plastic mass is mixed with the blowing agent, turns into a foam which is initially relatively soft and plastic, relatively quickly, but not faster than shaping. when it is tacky, but after a short time solidifies in a process comparable to hardening, so that the formed body acquires the desired mechanical strength and rigidity and dries.

Some methods have already been proposed for the design of tubular bowls from polyurethane plastic. According to one such method, a sleeve made according to a pipe to be insulated is made of cardboard or paper fitted to a rotating mandrel or core, after which the reaction mixture of polyurethane plastic is sprayed onto the sleeve. For practical reasons, this spraying could only take place with the sleeve rotating and with a relatively centralized jet moved in the longitudinal direction of the sleeve. This has resulted in the polyurethane layer being helically distributed on the outer surface of the sleeve, although the inner surface of the formed tubular bowl has become flat and relatively accurate in size, but the outer surface has remained uneven and ugly. Moreover, the uneven outer surface has made it difficult to bond the joints between the different parts of such pipe-bowl pieces. Moreover, the tightness of the foam when using an internal slender, which 58885 has often been made of a material whose properties include the ability to absorb moisture and stay moist for a long time, has led to greater corrosion of the pipes.

It has also been proposed, in order to reduce to some extent the unpleasant effects of this known method, to use as a substrate a paper strip sprayed with a polyurethane plastic reaction mixture which is allowed to foam but with the paper strip wound helically around the mandrel before the plastic is hardened. Coating with the reaction mixture has then taken place with a oscillating (= reciprocating) nozzle, which has proved to be the only practical device, but this has resulted in the foamed plastic not having a rectangular cross section but spent at the edges, more or less rounded so-called. to form "shoulders". Thus, even with this method, an uneven outer surface is obtained from a strip coated with polyurethane foam on a tube bowl formed by winding. Attempts to correct this mold defect by compressing the polyurethane foam before it has fully hardened have led to degradation of the foam structure and deteriorated thermal insulation as well as material losses.

When it has been a question of making hollow bodies of rectangular cross-section, e.g. for ventilation ducts, it has also been proposed by some interconnection method to assemble these ducts from four different plates or strips, preferably strips cut from a prefabricated body. This method becomes too complicated to be economically viable, as the part must first be made, then the strips must be cut and transported to their assembly point, where they are assembled into a channel of rectangular cross-section.

Finally, as a third step, the strips are joined into such a channel. Moreover, round moldings suitable for tubular bowls cannot be produced in this way, and if one of the methods described above is used to make round 58885 4 moldings, rectangular cross-sections cannot be produced, but such moldings are sometimes needed as a building material, e.g. .

The disadvantages listed above are eliminated by the present invention. The invention is characterized in that the mass is cast on flexible strip-shaped substrates as at least a substantially uniform coating and a plurality of such strip-shaped substrates with the masses applied thereto are assembled, optionally shaped together to form the desired hollow body, joining the edges of adjacent substrate strips in a known manner. run in the longitudinal direction of the hollow body, and that the assembly takes place when the foaming of the mass has at least substantially ended, but before the hardening, i.e., solidification, has taken place or only to a small extent has begun.

For example, German Pat. No. 1,222,652 already discloses a method for producing a hollow body as described above, without coating the strip-like substrates with a mass, in particular a polyurethane foam-forming mass, or by forming seams as described above. The formation of such seams is, on the other hand, known per se from Swiss patent publication 534,046.

The invention will be explained in more detail below with reference to the embodiments shown in the accompanying drawings, but the invention is not limited to these embodiments, and modifications may occur within the scope of the following claims.

In the drawings, Figures 1-4 show four different manufacturing steps of a rectangular duct, which duct is intended as e.g. a ventilation duct, while Figures 5-8 show corresponding manufacturing steps of a circular duct, which duct is intended to be used e.g. as a tubular bowl. Figure 9 is a schematic perspective view of an apparatus for making a continuous or discontinuous length from a tube bowl as described in connection with Figures 5-8.

5 58885

Although only four strips have been used in the application example of Figures 1-4 and only three strips in the example of Figures 5-8, it is clear that the number of strips used must be determined according to what is considered practical in each case.

Figure 1 thus shows an initial situation in the manufacture of a channel of rectangular cross-section. In this case, a core or mandrel 10 is used, which is shaped in such a way that it determines the internal dimensions of the formed channel. The mandrel is thus rectangular in cross section. A paper base 11 is arranged on all sides of the mandrel, which, before being introduced into the position according to Figure 1 or at the same time as being introduced into it, is sprayed or otherwise suitably coated with a still non-foamed layer 12 of foam, e.g. polyurethane. This plastic is then foamed so that the situation according to Figure 1 changes to that according to Figure 2, in which the foamed plastic is indicated by the number 12 '. When the plastic is at least substantially completely foamed, but before its stiffening and hardening has progressed to such an extent that the plastic is no longer moldable or no longer adhesive, the substrates 11 with their attached plastic layers 12 are moved towards the mandrel 10 to the position shown, with the initially curved shoulders 13 resting on each other. During the next light pressing against the mandrel 10, the curvature of the straws 13 is smoothed out, and these are interconnected due to the adhesion of the plastic, so that a channel with a cross-section according to Fig. 4 is obtained. The seams are then completely joined together and are therefore only marked with dashed lines 13 '.

The formed channel must be pulled forward along a fixedly arranged mandrel 10, the length of which must be such that the mass material has completely stabilized before the channel leaves the connection with the mandrel 10. In this case a continuous channel is thus formed, but of course nothing prevents channels of a certain length. If the duct is continuous, it must, of course, be cut to normal lengths during or after its manufacture.

58885 6

As mentioned above, Figures 5-8 correspond to Figures 1-4, but in this case a channel of circular cross-section is made of the three strips 14, which can be used, for example, as a tube bowl. In the same way as described above, three strips 14 are coated with a layer 15 of foamable and hardenable mass, e.g. polyurethane foam, which expands during foaming so that the position of Fig. 5 changes to the position of Fig. 6 where the expanded foam is marked 15 '. At a suitable point in this part of the manufacturing method, three strips 14 are passed around the mandrel 16. When the foaming has taken place at least in general, but before the hardening has progressed to such an extent that the plastic formability and adhesion of the pulp have disappeared, the three paper strips 14 with their foamed plastics 15 'are bent so that their round-shouldered edges face each other as shown in Fig. 7. is shown, and the shoulders are then pressed against each other, either by external pressure or by a small residual expansion of the foam, so that they join together to form seams 17, see Fig. 8.

The apparatus for carrying out the method, which is shown in more detail in Figures 5 to 8, is shown schematically and in a perspective view in Figure 9.

For the sake of clarity, the mandrel 16 is not shown in Figure 9, as it would cover details that should be visible. However, one skilled in the art will appreciate how this mandrel should be fitted. It should be mentioned in this connection that in many cases a mandrel is not even necessary, but manufacture can take place without such a mandrel, provided that the requirements for a certain precise shape accuracy are compromised with respect to the inside of the formed tube bowl.

The three strips of paper are denoted 18, 19 and 20 in Figure 9. They are each individually coated before being applied to the forming apparatus with a layer of foamable and temperable, but not yet foamed or tempered, 21, 22 and 23. The apparatus for coating this pulp layer is shown in Figure 9 only. but the device is, of course, at least substantially similar for the washers 18 and 7 58885 19. It should also be noted that the pads are described herein as being made of paper, which is of course a very suitable material, but in many cases a substrate of another material may prove more suitable, such as a plastic film, impregnated fabric or the like. Of course, the invention is not limited to the use of paper as a substrate, nor is it limited to the use of polyurethane foam as a pulp coating. Both of these substances should only be considered as application marks.

The coating with the pulp takes place by a spraying method using a nozzle 24 which can move back and forth along the guide 25 in an oscillating motion.

The three thus-coated strips 18, 19, 20 are then pulled forward over the rollers 28, 29 and 30 so that they move from their original at least almost horizontal positions to vertical or almost vertical positions, requiring the mass to be foamed on its way from the injection point to the roll, e.g. 30, to the extent that it is practically formable but no longer runs. It is thus solid-shaped in that it no longer changes shape or runs, but it is still plastically malleable.

The three tracks 18, 19 and 20 are selected in terms of their width so that they each correspond to a third part of the inner circumference of the forming tube 31 into which they are retracted, the mass-coated sides turned inwards. In this case, the compression of the shoulders takes place in the pulp coatings 21, 22, 23, which have been described in more detail above in connection with Figures 5-8.

The shaping tube 31, as well as the mandrel not shown in Fig. 9, must be so long that the formed tube, as it passes along these two parts, has time to stabilize as the mass stiffens and hardens. Thus, a tube with interconnected, barely perceptible seams, similar in type to that shown in Figure 8, emerges at the lower end of the device. This tube can then, depending on the area of use, be further machined. In the case of making a pipe bowl to insulate hot or cold pipelines, cut off

Claims (3)

58885 8 tube into suitably long pieces and the pieces are cut open along the baseline or possibly along several baselines so as to obtain tube bowls of conventional shape. The invention relates to a method for producing elongate hollow bodies, in particular tubular bowls or ventilation channels, from a foamable, hardenable or stiffening mass, e.g. polyurethane foam, possibly around a mandrel, characterized in that the mass is cast on flexible strip-shaped substrates (e.g. 18, 19, 20) as a coating (e.g. 21, 22, 23) and a plurality of such strip-shaped substrates (18, 19, 20) with the masses (21, 22, 23) fitted thereto are assembled, optionally shaped, together to form the desired hollow body, whereby adjacent substrate strips (18, 19, 19) , 20) the edges (e.g. 13. are joined in a known manner so as to form seams (e.g. 13 '/ 17) running in the longitudinal direction of the hollow body and that the assembly takes place when the foaming of the mass is at least substantially completed, but before hardening, vast, solidification has occurred or only a small amount has begun. In carrying out the method according to claim 1, seams (13 '; 17) are provided between the strips (18, 19, 20) so that the hollow body takes the form of a tube. When carrying out the method according to claim 1 or 2, the substrate strips (18, 19, 20) are guided in at least an almost horizontal plane when they are coated with the mass (21, 22, 23). After the pulp has dried so that it is no longer flowable but still has to be plastically shaped, the base strips (18, 19, 20) are turned around the rollers (28, 29, 30) or the like in at least a substantially vertical direction and joined to form a hollow body.