DE2166791A1 - PROCESS FOR MANUFACTURING PIPES FROM PLASTIC-METAL LAMINATES - Google Patents

Description

Applicant: Austral-Erwin Engineering Company,

2700 Exxon Building, Houston, Texas, V. St. A.

Process for the production of pipes from plastic-metal laminates

The invention relates to a method of manufacture of tubes made of plastic-metal laminates, which consist of a flexible sheet of metal that is placed on or on Both sides are completely coated with one or more heat-sealable plastic films without air inclusions is.

Plastic-metal laminates, where plastic films are applied to a metal surface and are connected to this essentially without air inclusions known. A newly developed process has made it possible to produce plastic-metal laminates in which poly-

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More fluorocarbons used for coating can be produced in a very economical manner. There such fluorocarbons are particularly resistant as well as being completely corrosion-resistant and subject to little pollution and slagging, they are preferred substances for coating metal surfaces in industrial plants, where it is necessary, such metal surfaces to protect against corrosion and wear, to prevent or at least to prevent the formation of deposits and in order to make them wettable, in particular with oil. But it is well known that it is very difficult and time-consuming and often not economical it is feasible to apply plastic coatings on curved, i.e. convex and especially concave surfaces, so that the coating of pipes and pipelines is great for a wide variety of applications Offers problems. For this reason, for example, rust-proof and corrosion-resistant lines are often expensive Metal alloys, such as copper-nickel, are used. Such pipelines are, for example, profitable for Sea water stills, heat exchanger piping or systems, and the like, are prohibitive. Therefore Coated metal parts are still used.

In known processes for coating concave surfaces, i. H. including the inner surfaces of pipes and Pipelines, is cemented and cemented, whereby mandrels, inflated bags and the difference in heat dissipation expansion of the polymer and the metal are used to pressure contact of the plastic film with the concave to create curved surface. It has been shown that

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Films that have been applied to concave surfaces without adhesive putty are unsatisfactory in terms of quality and thus economically. The processes themselves are costly and limited to short pipelines. Cementing or cementing a film on curved surfaces is also relatively expensive and therefore unsuitable for many possible applications, since the surfaces must be prepared for this and the very thin films must be carefully treated. In the case of small pipes, such as 25.0 mm and 19.05 m, which are commonly used in the long pipe systems in heat exchangers in sea and seawater distillation systems, no means are known for lining or coating with thin polymeric fluorocarbon To allow films economically in accordance with the costs appropriate for such systems. Economic efficiency can neither be achieved by coating with an applied film nor by using sintered, dispersed particles.

It is the object of the invention to provide a method of production of pipes made of plastic-metal laminates, which can be carried out easily and economically, regardless of whether the pipe is only on the inside or only on the On the outside or on the inside as well as on the outside is coated with plastic and which makes it possible Manufacture high quality corrosion-resistant pipes.

This task is accomplished by a method of the type mentioned at the beginning Type solved, which is characterized in that a prefabricated plastic-metal laminate is used which has exposed strips of the plastic coating to form the pipe seam, which when the

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Laminate placed one on top of the other in the pipe form, these overlapping pipe seam strips with a forming device in brought into close contact and then welded together by heating.

The plastic-metal laminate can be guided through a conventional tube forming device. To make it easier the passage through the pipe former and to prevent the plastic coating from being removed during heating sticks to the surfaces of the former, one or both sides of the laminate is coated with a lubricant and anti-stick agent Mistake. The bendable metal sheet, which is used as the metal core of the pipe, can be one or both sides be coated, the one-sided coating either as the inner surface or as the outer surface of the pipe can serve. In the case of a laminate coated on one side, the pipe seam is formed on the one opposite the coating A plastic strip is applied to the surface of the exposed metal sheet, which is then used when the Tube is welded to the seam area on the coated side of the metal sheet. Furthermore, one edge of the Sheet metal are exposed during manufacture of the pipe is embedded in overlapping plastic seam strips. The tube can also be helical Wrap the plastic-metal laminate on top of one Mandrel are produced, also overlapping plastic strips are welded together and form a spiral pipe seam.

In this way it is possible to make metal pipes and piping very economical to manufacture, the flawless even with the very corrosion-resistant and therefore for many Plants in industrial systems are very advantageous and

ORIGINAL INSPECTED

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valued polymeric fluorocarbons are coated.

Apart from the simplicity of the method according to the invention, the pipes produced in this way have excellent properties Quality that surpasses that of the known coated pipes. The plastic-metal laminate is in shape a straight bendable or convex sheet metal prefabricated, so that the difficulties of coating a concave Surface, i.e. the inner pipe jacket, are completely switched off. It is guaranteed with certainty that the coating is flawless and without air pockets. The pipe seam is made without additional adhesives, putty or welding agents produced in a simple manner completely firm and tight.

The invention is illustrated by some in the drawings illustrated embodiments explained in more detail. Show it:

Fig. 1 is a schematic representation of a tube forming device for producing a tubular body made of a plastic-metal laminate;

Fig. 2 is a schematic representation of a somewhat modified embodiment of such a pipe device ;

Fig. 5 is a sectional view of a three-layer plastic-metal laminate that is to a tubular body can be formed in the devices of Figure 1 or 2;

4 and 5 are sectional views of other embodiments of the plastic-metal laminate with im Seam strips arranged at a distance from one another

ORIGINAL INSPECTED

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on the uncoated metal surface j

6 shows a partial cross-sectional view of an overlapping seam area to be welded of a three-layer pipe j

FIG. 7 is a view similar to FIG. 6 showing a two-layer pipe made of a plastic-metal laminate, the seam of which for welding according to FIG. 6 is exposed;

Fig. 8 is a view similar to FIG ¹ J, which shows a slightly modified embodiment of the laminate. and

Fig. 9 is a schematic representation of an arrangement for pulling a bendable tube from a Plastic-metal laminate, its cross-section is round and when passing through a shape a longitudinally wavy or receives fluted profile.

In the method according to the invention for molding a Tube or a tubular body, a plastic-metal laminate is used, in which an edge region of the is exposed on the bendable metal applied plastic film to form a seam. These seam areas or seam strips are laid one on top of the other, heated and welded to one another in the process. The plastic coating consists preferably of a fluorocarbon polymer, for example tetrafluoroethylene or a Copolymer, hexafluoropropylenetetrafluoroethylene. The laminate is conveniently moved by conventional pipe forming apparatus and is preferably made with a Silicone lubricant pre-coated to the passage by the shape to facilitate.

ORIGINAL INSPECTED

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In the pig. 1 and 2 schematically shows an arrangement for forming a plastic-metal laminate, where 'heat but no additional pressure sensitive adhesive than that Plastic layer itself is used. The process is based on coated with hydrofluorocarbon Metal sheets described.

In the arrangement of the device according to FIG. 1, a Prefabricated plastic-metal laminate with a longitudinal seam and the device according to FIG. 2 with a spiral suture made.

Both methods have certain advantages, but it has been found that the formation of a longitudinal seam one spiral suture is preferable. The longitudinal seam requires compared to the spiral wound seam about $ 20 less flat material when making of a pipe with the same overlapping seam area., which determines the strength of the seam. To one both on the inside and on the outside with plastic coated pipe with an inner diameter of 19> 5 mm make a 76.2 mm wider, with on both sides Plastic coated metal strips are used. Such a strip (Fig. 3) consists of a bendable one Sheet metal 4j5 and the two plastic layers 42, which preferably consist of copolymeric hexafluoropropylenetetrafluoroethylene exist. A plastic-metal laminate 53 assembled in this way is pulled off a roll 52 and first through a device 54 (not shown in detail) moves, in which the laminate is coated on both sides with a lubricant, e.g. silicone oil. Through this treatment the laminate strip can pass through the forming device more easily

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are guided and it is prevented that he is when welding the seam adheres or sticks to the mandrels. To form a pipe with an overlapping longitudinal seam, the silicone-coated composite laminate strip 55 becomes in and through a die mold 56 (not shown in detail) out. The strip leaves this die form as a tube 57, its overlapping The seam is not glued. The tube so formed is then moved through a heated mold 58, viz with enough close tolerance to easily fit any overlapping area into those adjacent to them, with plastic embed the coated surface. The two seam strips are firmly connected to each other and the raw one exposed edge of the metal is embedded and welded. Such an edge was formed as that with Plastic-coated sheet metal in strips of the desired width - in this case 76.2 mm - was cut. Of the strips fed into the apparatus from roll 52 53? comes after passing through the individual stations 54 - 58 out as a welded tube 59 that continuously can be made in lengths equal to the length of the supply strip 52 on the roll.

A pipe cross-section is welded at 60 to one overlapping seam, which in this case is about 12.7 nm wide. Tensile strength tests of Sections of pipe with an inner diameter of 19.05 mm, made from 0.127 mm thick, soft aluminum with a 0.0254 mm thick hexafluoropropylene tetrafluoroethylene layer on each side, showed that an overlapping 12.7mm weld was much stronger than that Laminate itself. The pipe wall failed at temperatures

ORIGINAL INSPECTED

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up to 204.5 ° C, but not the weld if it has been subjected to tensile stress. To a spiral To produce a wound tube, the silicone-coated plastic-metal strip 61 is removed from the coating device 54 on a mandrel in level 62 (not in individually shown) moved and welded in stage 65 or heat-glued. The tube formed in this way is detached from the mandrel at 64 and comes as a welded spiral tube 65 out. A strip pre-coated with silicone oil makes it possible to use a winding mandrel and this to heat. Otherwise the strip would stick to the mandrel. In these experiments it was found that one Silicone treatment of a fluorocarbon film bonded to the metal prevents the plastic from bonding to other metals even at 3l6 ° C, but still no noticeable adverse effect on the adhesiveness of the previously bonded to the metal Exerts fluorocarbon sheets against one another, d. H. sticking to itself is not affected. This fact makes the very important use of the Silicone oil coating possible. So far it has only become known to apply a silicone coating to the mandrels, around unsealed fluorocarbon foils that are not themselves coated with silicone oil to stick to prevent. When making this pipe, the use of a "pre-welded" or "pre-glued" Fluorocarbon meta-11 laminate vital, because unconnected superimposed Layers of fluorocarbon foil and metal do not adhere properly to each other if they form a tube with an overlapping longitudinal seam or with a spiral overlap Seam to be shaped.

ORiGiNAL INSPECTED 509887/0859.

Fig. 3 shows a plastic-metal strip 43 with fluorocarbon films 42 and 42, preferably polymeric, previously welded on both sides Hexafluoropropylenetetrafluoroethylene, which has a width of 76 * 2 mm, in order to be able to use a on both the interior and also produce a pipe coated on the outside with an inner diameter of 19 * 05 mm.

Fig. 4 - and in a similar form Fig. 5 - shows a corresponding wide sheet metal 43, with one as well

wide, pre-welded fluorocarbon film 42 on one side and 25.4 mm wide fluorocarbon strips 44 on the other side, with a distance of 127 mm between these strips 44, 44 being provided. This sheet laminate is split as shown in the middle of the 25.4 mm strip at 47 and in the middle of the distance between two 25.4 mm strips at 48. This results in the strip shown in FIG. 5, which consists of a 76.2 mm wide metal sheet, which on one side has an equally wide welded fluorocarbon film 42 and on the other side a 12.7 mm wide strip 44 of ψ fluorocarbon is provided. One edge of this last-mentioned strip 44 lies flush with an edge of the metal sheet. This laminate can be passed through the work steps shown in FIGS. 1 and 2 to form a metal tube with an inner diameter of 19 * 05 mm, which is similar to the tubes 60 and 65 in FIGS. The welded-on fluorocarbon foil is either on the inside or on the outside of the pipe. In each case, the metal surface is exposed on the opposite side.

ORIGINAL INSPECTED

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Where the coated or uncoated side is, depends on the manner in which the composite strip is inserted into the die form 56 or for spiral winding in Level 62 is introduced. Because the previously welded fluorocarbon layer in the presence of silicone (which is supposed to prevent sticking to the thorns or other coated surfaces) not easy with the raw Metal can be joined, the 12.7 will now be strip on the exposed side of the sheet metal needed to create a good bond and still use it of the silicone non-stick agent.

Fig. 6 shows an overlapping seam and illustrates how this is connected and the exposed edge of the raw metal is welded when the metal is coated with fluorocarbon on each side to create a Completely coated on the inside and outside Form tube. The sheet metal is 43, the fluorocarbon coating with 42 and the weld on the metal edges with 45.

7 shows one provided with an overlapping seam 45 Laminate strip in which one side of a metal strip 45 is completely covered with the plastic film 42 is. On the opposite, exposed side of the metal sheet, this laminate strip is on an edge section 45/42 a plastic strip 44 is applied. A such a laminate can result in a tube with a completely coated inside and a bare metal surface on the outside and a weld 45 on the inner edge of the metal, where the strip 44 adheres to the coating 42.

ÖRSÖiNAL INSPECTED

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Pig. 8 shows in cross section an overlapping seam of a pipe made of a plastic-metal laminate, in which the fluorocarbon film completely covers one side of the metal sheet and the other side only in the edge area. A pipe made from this laminate has an outside completely coated with fluorocarbon and an inside made of bare metal. The same reference numerals are used as in the other figures, namely sheet metal K ^>, the continuous fluorocarbon coating 42, the narrow fluorocarbon strip 44 and the weld seam 45 on the metal edge.

One produced by the method according to the invention Pipe made from a plastic-metal laminate can also be easily provided with a profile of the pipe jacket be provided, which can be corrugated, fluted, grooved, ribbed or corrugated in the longitudinal direction.

9 shows a schematic arrangement for production of a tube with a tube jacket that is corrugated in the longitudinal direction. A finished tube 59 is formed by a conventional die shape 66 drawn, which leaves it as a tube 67 corrugated in the longitudinal direction. Such profiling is the The outer diameter of the pipe is reduced and prepared in this way for corresponding further uses.

OB / GJNAL INSPECTED

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Claims (1)

Ί 1667 P_a_t_e_n_t_a_n_s_g_r_ü_c_h_e 1. Process for producing a pipe from plastic-metal laminates, which consist of a bendable sheet of metal, which on one or both sides with one or more heat-sealable plastic film is completely coated without air inclusions, characterized in that a prefabricated plastic-metal laminate is used which
has exposed strips of the plastic coating to form the pipe seam, which are superimposed when the laminate is bent into the pipe shape, these overlapping pipe seam strips are brought into close contact with a mold and then welded together by heating. 2. The method according to claim 1, characterized in that the plastic-metal laminate by a conventional tube forming device to be led. 3 · The method according to claim 2, characterized in that
To facilitate the passage through the pipe forming device, the plastic-metal laminate is coated on both sides with a lubricant and anti-adhesive agent, such as a silicone oil. 4. The method according to claim 1 to ~ $, characterized in that a metal sheet completely coated with plastic on both sides is used. 5. The method according to claims 1 to j5, characterized in that that one either only on the inside or only on the ORIGINAL INSPECTED 50 98 87/0859 Tube coated on the outside made of sheet metal completely coated with plastic on only one side is made, being in front of the passage of the plastic-metal laminate by the pipe forming device on the side of the metal sheet opposite the coated side a narrow plastic strip is applied as a seam strip and this over the seam area of the completely laid with plastic-coated side and then welded to this by heating P will. 6. The method according to claim I _3, characterized in that on the inside and / or on the outside exposed metal edges of a metal core of a laminate to be formed by welding overlapping edges to form a tube embedded in the softened adjacent plastic compound during passage through a closely fitted heated molding device and be welded with it. 7. The method according to claim 1, characterized in that the plastic-metal laminate in the form of a strip guided in and through a pipe forming device and in it to a pipe with an unconnected * in the longitudinal direction running overlapping seam is formed, this tube is moved through a heated molding device and thereby formed the pipe seam by softening and welding the overlapping plastic seam strips will. 8. The method according to one or more of claims 1 to 7> characterized in that the plastic-metal laminate ORIGINAL INSPECTED B 0988 7./0859 b & 791 in the form of a strip spirally wound around a mandrel and into a tube with a spiral overlap unbonded seam is formed, then this tube is moved through a heated forming device and the two contacting surfaces of the overlapping plastic strips forming the seam and softened together be welded. 9 · method according to one or more of claims 1 to 8, characterized in that as a plastic-metal laminate one or both sides with a polymeric fluorocarbon, such as tetrafluoroethylene or hexafluoropropylene tetrafluoroethylene coated bendable metal sheet is used. ORIGINAL INSPECTED ¹ P ^r 4 u ί! 7 / 0B ^c i