WO1983002599A1 - Method for producing prefabricated elements having large surfaces, particularly sailing boards - Google Patents

Abstract

Process for the production of a flat prefabricated element, in particular a windsurfing board, from a prefabricated foam core and from two half-shells attached to this core and to each other. At the joint line of the two half-shells, the foam core has dimensions less than the prescribed dimension. The resulting empty space between the foam core and the half-shells is filled with a molding material after closing the negative mold. This prevents the negative mold from closing when foam overflows at the joint line, which could hinder subsequent welding of the edges of the half-shells. In addition, the molding material makes the joint line impact resistant by its reinforcing effect, thereby eliminating any possibility of bursting, even if the prefabricated element is subjected to high stresses.

Description

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Method for producing a large-area component, in particular a sailing board.

The invention relates to a method for producing a large-area component, in particular a sail board, by inserting a prefabricated foam core, in particular an EPS foam core, between two half-shells in a negative form and connecting the half-shells to one another and to the foam core by closing the negative mold, a core zone made of impact-resistant mass being provided along the connecting seam.

Foam cores, which have a certain amount of foam, are used in the manufacture of sailing boards by this method

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OMPI ^ WlfO Have oversize so that when the half-shells are joined together in a mold, they form a good adhesive or welded connection with the shell material over their entire surface. DE-OS 30 19 535 describes a process for the manufacture of a sailing board, in which a structure is first produced from a central longitudinal belt and a central piece from a medium-density foam which is embedded in a low-density foam and from a foam jacket made of high-density shockproof foam. This foam core is made with oversize, which creates the required pressure during the curing process in the closed mold.

Foam cores, especially those made from EPS foam (expanding polystyrene) lung shrink slightly after its Herstel¬ so that shrinkage dimensions advertising considered dne must, which in turn causes that must be taken into account in total rela¬ tively high seeds ^"dimensional tolerances in prefabricated foam- From this it follows that a considerable excess must be provided so that a secure connection between the foam core and the shell material is ensured even in the event of more shrinkage. This in turn leads to the problem that a material accumulation can occur in the edge area. which is particularly harmful if the half-shells have outward-facing edges which are to be squeezed together and thereby welded to one another, since the foam core material can penetrate into the area of the weld seam, so that inadequate or no welding takes place Such an inadequate Welding the half-shells later on, when using the sailing board, can cause the weld seam to burst open and water to penetrate, which is particularly the case with to an EP S-Scha umk, that this water has not come up, we can not have it any more.

The invention has for its object to provide a method of the type mentioned, which ensures a flawless connection of the half-shells and results in a circumferential seam that withstands even the heaviest loads.

This object is achieved according to the invention in that the foam core is made to an undersize in the area of the connecting seam and the resulting space between the foam core and half-shells is filled with a casting compound after the negative mold has been closed.

The undersize of the prefabricated foam core provided according to the invention avoids any entry of foam material into the seam area, so that the welding of the half-shell edges that may be provided cannot be impaired. In addition, there is the advantage that the cavity caused by the undersize allows air to escape which is still in the component when the shells are joined to the core and would otherwise impair the adhesive or welded connection between the foam core and the shell material . After the shells have been joined together with the core, the cavity is filled with the casting compound, which makes the connecting seam impact-resistant due to its reinforcing function, so that bursting can be reliably ruled out even when the component is subjected to the greatest stress.

If the component has a curved profile at the connecting seam of the half-shells, which is usually the case, the undersize is advantageously achieved by removing the foam core along the circumferential connecting seam. is flat. Such a flattening can in particular also be retrofitted to the prefabricated foam core, advantageously directly before the pressing process, since then a precisely defined cavity can be reached when the shells are joined to the core. Should the shell curvature at the connecting seam be too small, however, the required cavity can be achieved by a groove with a circular segment-shaped cross-section running along the circumferential connecting seam.

Two-component PU foam aces, silicone compound or epoxy casting resin, for example, are provided as the permanently elastic casting compound.

The casting compound provided according to the invention not only performs the function of filling the cavity remaining along the seam and thus increasing the strength of the joint seam, it also performs the adhesive function, so that it is possible according to a further development of the invention to use the half-shells exclusively to be glued to one another by means of the casting compound filling the cavity and to dispense entirely with a weld seam. In this embodiment, the half-shell edges meet practically butt.

The invention can be used wherever flat components are produced from at least two shell parts and a prefabricated foam core. In addition to the manufacture of sailing boards, the manufacture of wind deflectors or spoilers for motor vehicles, in particular above the driver's cab of trucks, of door leaves, facade cladding elements, boat hulls and the like. Large-area components by the method according to the invention is advantageous. The invention is explained in more detail below on the basis of the description of exemplary embodiments with reference to the drawing. Show it:

1 shows a sectional illustration in the region of the connecting seam of the half-shells of a sailing board with a prefabricated foam core in which the half-shell edges are welded to one another and

2 shows a sectional illustration in the region of the connecting seam of the half-shells of a sailing board with a prefabricated foam core in which the edges of the half-shells are not welded to one another.

As FIG. 1 shows, the sailing board 1 consists of two half shells, namely an upper shell 2 and a lower shell 3, which enclose an EPS foam core 4. To produce this sail board, for example, two sheets of thermoplastic material are simultaneously deep-drawn in negative drawing tools. In the still plastic state of the half-shells, the prefabricated EPS core is fed in and the two half-shells are welded to one another and to the EPS core 4 using a compressive force. The material protrusion at the weld seam 5 is then removed along the broken line 6.

The prefabricated EPS core 4 has a slight oversize, so that it is welded over the entire surface to the thermoplastic shell material. Only along the weld seam 5 does the EPS core 4 have a flattening 7, which creates a cavity 8 during welding. The flattening 7 can be seen directly when the core 4 is foamed; however, it is also possible to flatten the core only after the EPS core has been adequately stored. bring so that the cavity 8 can be given a desired volume regardless of the volume shrinkage of the EPS core 4 after its manufacture. The height h of the flattening is 5 mm, for example.

When the shells 2, 3 are joined together with the EPS core 4, air which is still inside the shells collects in the cavity 8 created by the flattening 7 during welding and is guided to the outside when or after the half shells are joined together. The cavity 8 is subsequently filled with a high-strength casting compound 9 via bores in the shell leading into the cavity, air contained in the cavity 8 escaping through corresponding bores. As a result of its high strength, the casting compound forms an excellent reinforcement of the connecting seam running around the weld seam, which in this way can withstand the highest stress.

As the casting compound 9, for example, two-component PU compound, silicone compound and epoxy casting resin can be considered. These casting compounds can in particular also be reinforced with glass fibers. If the casting compound consists of a material which forms a good adhesive connection with the shell material, the edges of the half-shells 2, 3 can be completely welded away. An example of this is shown in FIG. 2. In this exemplary embodiment, the material protrusions that are not welded to one another are removed along the dashed line 10 after the casting compound 9 has produced a permanent, sealed adhesive connection to the edges of the half-shells 2, 3.

The invention is not directed to the manufacture of sailing

OMPI boards, still limited to the materials mentioned. For example, the half-shells do not have to be produced in the deep-drawing process and also do not have to be made of thermoplastic. It is sufficient if the shell material can be glued to the material of the foam core, the material for the foam core, of course, not necessarily having to be EPS. All foams that can be glued or welded to the shell material are possible. Instead of the welding of the shell edges shown in FIG. 1, normal gluing is possible in the same way, after which the circumferential cavity 8 is then filled with casting compound 9.

Finally, instead of the flattening 7, the seam 5 of the half-shells can also be opposed to an arching of the surface of the prefabricated foam core to form the cavity 8, which is particularly advantageous if the shells in the area of the seam 5 run in one plane.

Claims

Claims 1. A method for producing a large-area member, especially a sailboard, gene by Einle- ^'a preformed foam core, in particular an EPS show core, between two half-shells in a negative mold, and connecting the half-shells mit¬ and with each other the foam core by closing the negative mold , a core zone made of impact-resistant material being provided along the connecting seam, characterized in that the foam core is made with undersize in the area of the connecting seam and the resulting space between the foam core and half-shells is filled with a casting compound after the negative mold has been closed. 2. The method according to claim 1, for producing a component which has a curved profile at the joint seam of the half-shells, characterized in that the foam core is flattened along the circumferential joint seam. 3. The method according to claim 2, characterized gekennzeich¬ net that the foam core is made flattened by about 5 mm. 4. The method according to any one of the preceding claims, characterized in that two-component PU foam compound is used as the casting compound. 5. The method according to any one of the preceding claims 1 to 3, characterized in that silicone compound is used as the casting compound. 6. The method according to any one of claims 1 to 3, characterized in that epoxy casting resin is used as the casting compound. 7. The method according to any one of the preceding claims, characterized in that the edges of the half-shells are connected to one another solely by the casting compound. 8. Large-area component, in particular a sailing board, made of a prefabricated foam core, in particular an EPS foam core, and two half shells connected to this and to one another, characterized in that the foam core (4) in the region of the connecting seam (5) of the half shells (2 , 3) has undersize and the resulting cavity (8) is filled with a casting compound (9). 9. Large-area component according to claim 8, characterized in that the edges of the half-shells (2, 3) are welded together. 10. Large-area component according to claim 8, characterized in that the edges of the half-shells (2, 3) abut each other and are connected to one another via the casting compound (9).