DE3406689A1 - Sailboard and process for the production thereof - Google Patents

Abstract

A sailboard (10) has a core (11) made of foam and an outer skin (12) made of a smooth, impact-resistant plastic. The core and the outer skin (12) are adhesively bonded to one another via an adhesive layer (14). Unidirectional fibre bands (15) are inserted between the core and outer skin and bonded to the core (11) by adhesion (19). Sailboards of this type are distinguished by increased stiffness as regards the flexural strength in the longitudinal direction. <IMAGE>

Description

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DESCRIPTION

Sailboard and process for its manufacture

TECHNICAL AREA

The invention relates to a sailboard with a foam core surrounded by an outer skin via an adhesive layer, and a method for its production.

STATE OF THE ART

Sailboards are manufactured using a wide variety of processes. As a result, there are numerous, different ones Constructions known. A currently common construction is one in which the outer skin consists of two half-shells made of acrylic-styrene-acrylic ester (ASA). The half-shells surround a foam core made of expandable Polystyrene (EPS), and they are bonded together around their edges. To produce such a board, a preformed one is used Core used, which is coated with a polyurethane (PU) adhesive. Two ASA poles are made in one mold heated, and then drawn into a mold half by means of a vacuum drawing process. Between the half-shells shaped in this way, the prefabricated core is inserted, and then the half-shells are pressed against one another under the constant action of heat, so that their edges together fuse and the core is enclosed in the closed outer skin formed in this way. The PU hot glue at the same time creates a secure connection between the EPS core and the ASA outer skin.

Another manufacturing method and a different construction of a sailboard are known from US Pat. No. 3,929,549. It will there two fiberglass half-shells are used for the outer skin.

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These are filled with foam and then covered with an epoxy resin layer glued together. The half-shells correspond to the two parts of a sailboard that are created when the board is divided lengthways by a plane perpendicular to the top of the board. the adhesive epoxy resin layer along this partial plane is relatively strong. This means the board is opposite Stiffened bending loads. *

Also the surfboards mentioned at the beginning with a plastic outer skin and foam core often need auctioning Components, also called stringers. These stringers are made of light wood or thin aluminum sheets. These stringers, be they epoxy resin, wood or sheet metal construction, always lead to one relatively large increase in weight of the board.

DISCLOSURE OF THE INVENTION

The invention is based on the object of specifying a sailboard and a method for producing a sailboard, which is characterized by its low weight and high flexural rigidity.

The invention is for the sail board by claim 1 and for the method of making a sail board by Claim 10 given. Developments and refinements of the invention that are inventive per se are the subject matter of Subclaims. The features according to the subclaims can also be used together if they are not mutually exclusive.

The sailboard according to the invention has a fiber insert between the plastic outer skin and the foam core. the

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Fiber insert is with the foam core and with the outer skin glued. It is particularly advantageous to have a unidirectional fabric that is aligned with the pasers in the direction of travel is misplaced to use. This is because the pasers then have a particularly pronounced effect on stiffening in the longitudinal direction at .. To achieve a sufficient degree of stiffening, it is sufficient to use only individual slivers to use, which is obviously advantageous in terms of weight savings compared to a full-area insert.

High rigidity in terms of deflection in the longitudinal direction and in terms of rotation about the longitudinal axis at extraordinary low weight results when individual unidirectional slivers are used that are inclined are relocated to the direction of travel.

The method according to the invention is characterized in that a prefabricated core is provided with an adhesive layer and a fiber layer that will later form the pas insert will. An adhesive is applied to the fiber layer, which secures the fibers and the

material core well wetted. The core prefabricated in this way is between two heated half-shells are introduced, which are then joined together, which advantageously involves fusing their edges, but can also be done by gluing. In this process, the pas insert is glued with the foam core and with the outer skin and fastening the half-shells together in one operation. The half-shells are made by heating plastic films and drawing them into the mold halves using negative pressure produced, the production step for the half-shells can also be included in the process sequence for producing the Board can be integrated. The inventive method

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So a light and rigid sailboard can be produced in a simple and cheap way.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is illustrated in more detail below with reference to figures. Show it:

Pig. 1 is a plan view of a sailboard;

FIG. 2 shows a cross section through the sailboard according to FIG. 1 along the line 2-2;

Fig. J5-5 a schematic representation with two mold halves a manufacturing device, for explanation

of the manufacturing process of the sailboard according to FIG. 1.

WAYS OF CARRYING OUT THE INVENTION

The sailboard 10 according to FIG. 1 has an EPS foam core 11 and an ASA outer skin 12. The outer skin is made up of an upper half 12.1 and a lower half 12.2 formed as they can be seen from FIGS. 3-5. In the finished state of the board, the two halves are welded together so well along their edges that in a section according to FIG. 2 no transition between the upper half and lower half is more recognizable. Rather, a closed, smooth outer skin 12 is then formed. This is with the core 11 via a PU adhesive layer tied together.

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Four fiber ribbons 15 made of unidirectional glass fiber fabric run between the core 11 and the outer skin 12. Two bands are at the top and two are at the bottom of the board 10. The belts run obliquely to the direction of travel 16, namely as follows that they cross near the front end of the sailboard 10 and near the rear end I7 at one each Page margin 18 ends. The slivers I5 are glued over PU 19 connected to the outer skin 12 and also to the core 11. The bond I9 extends from a few millimeters to a few Centimeters into the core 11, in which it fills cavities between the individual grains of the ASA foam.

The sailboard 10 according to FIGS. 1 and 2 is produced using a method as illustrated with reference to FIGS. 3-5 is.

3.5 Two mold halves 20 of a manufacturing device are held at a distance from one another. ASA foils 22 for producing the upper half 12.1 and the lower half 12.2 of the outer skin 12 are placed over the mold depressions 21 of the mold halves 20. The mold recesses 21 are each connected to a vacuum connection 23. The two foils 22 are adjacent and parallel to one another. A radiant heater 2.K is pushed between them. This heats the films 22 to about I70 ⁰ C. The mold halves 20 are heated to about 100 ⁰ C. At these temperatures, the foils 22 become so soft that they can be drawn into the mold depressions 21 by negative pressure. This retracted state is illustrated in Fig. K right.

In FIG. 4, on the left, a core 11 provided with the adhesive layer 1h and the fiber tapes 15 is shown. The core 11 is in a special shape by foaming or by

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High-temperature treatment of a granulate introduced into the mold. A dispersion of a PU hot-melt adhesive is then sprayed on in water. After the water has evaporated, the core 11 is provided with the adhesive layer 14. The four glass fiber tapes 15 are then placed on the core 11 with the adhesive layer 14 and fixed thereon by means of a fast-acting adhesive. A bead of adhesive 25 made of a paste-like PU adhesive is then applied to each of the slivers 15. This adhesive becomes very thin ^{at about 50 ° C.} The volume of the adhesive bead is dimensioned such that in the liquid state all cavities between the fibers of the fiber tapes 15 are filled and the adhesive penetrates a few millimeters to a few centimeters into the core 11.

The prefabricated core 11 according to FIG. 4 on the left is inserted into the prefabricated half-shells of the outer skin 12 according to FIG. 4 on the right. The two mold halves 20 of the manufacturing device are then moved towards one another, as shown in FIG. 5. The hot halves 12.1 and 12.2 initially hit the adhesive beads 25 and liquefy the adhesive. Then the fiber tapes 15 are pressed somewhat into the core 11 until the halves 12.1 and 12.2 meet the adhesive layer 14. This activates the hot glue of the adhesive layer 14 and forms the connection between the core 11 and the halves. The volume of the core 11 is dimensioned so that it can still be pressed together until finally the edges of the upper half 12.1 and the lower half 12.2 lie against each other. These edges then merge with one another, so that finally the closed outer skin 12 according to FIG. 2 is formed. The mold halves 20 are then cooled with the enclosed by them sailboard within about 5 minutes at 50 ⁰ C. In these times

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the adhesive of the adhesive beads 25 penetrates into the core 11. Finally, the finished sailboard becomes the manufacturing device taken. The PU adhesive of the adhesive beads 25 then needs some time until it is completely hardened, so that the final stiffness of the board is only reached after a few days is.

A sailboard according to FIG. 1 has, for. B. a length of 377 cm, a maximum width of 60 cm and a maximum height of 1.5 cm. The displacement is about 230 liters and the weight is about 16 kg. This weight is about 10 % lower than in the case of a conventional board, since the outer skin 12, which is decisive for the weight , can be reduced in its thickness by about 15% while still ensuring greater rigidity than with previous boards.

If a conventional board with an ASA outer skin about 2.7 mm thick is clamped at its rear end 17 and about 3 m in front, and is then loaded with about 100 kp in the middle between the clamping points, the deflection is about 37 mm. In the case of a board according to the invention, the deflection in a 2.3 mm thick ASA outer skin is only about 17 mm. Only when the thickness of the outer skin is about. 2 mm, i.e. reduced by about 25% compared to conventional wall thicknesses, the same deflection is achieved again. Such a board is then about 20 % lighter than a conventional board. With the increase in rigidity, an improvement in the damping properties can be observed almost in parallel. If the front, free end of the surfboard is deflected with the specified type of clamping and then released, it swings up and down for a while. With the board according to the invention, the decay time is only about half as long as with a known board

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without glass fiber tapes between the core 11 and the outer skin 12.

Instead of an outer skin 12 made of ASA, any desired outer skin material can be used can be used, which is smooth and hard-wearing, and also for other, conventional sailboard constructions suitable is. Correspondingly, instead of EPS for the core 11 and instead of PU for the adhesive layer 14 or the bond 19 any other material used in other sailboard constructions can be used. But it is important that the adhesive for the adhesive layer 14 is chosen so that it glues the core 11 and the outer skin 12 securely to one another and that the material for the bond 19 is chosen so that it at least the fiber ribbons 15 securely with the core 11, advantageously but also still connects to the outer skin 12. It is particularly advantageous to use an adhesive to use, which wets the material of the core 11 well, so that it is as deep as possible into the pores between the grains the core material can penetrate. A particularly strong bond between the core 11 and the fiber ribbons 15 is then achieved. The material of the core 11 and the outer skin 12 should be matched to one another so that they differ in their strength do not influence each other, so that ζ. Β. not plasticizers from the outer skin 12, the material of the core 11 destroyed. If the outer skin 12 contains such materials, the adhesive of the adhesive layer 14 must be selected accordingly, that it prevents the exchange of substances which are harmful to one of the neighboring materials.

For the fiber ribbons 15 were in a practical unidirectional glass filament fabric with a tear 30

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force in the longitudinal direction of ΙβΟΟ N / cm and across it a Tear force of 175 N / cm with about 0.5 mm thick fibers used. ^

'-The tapes were 8 cm wide upset. The same stiffening effect can also be achieved when using double-width, half-thickness belts. Thinner but wider material will preferably used when the tapes are laid in such a way that crossover points occur in greater numbers, especially if more than two layers cross each other. It should be noted that the slivers are to be pressed into the core 11 when the half-shells of the outer skin are pressed on. This results in greater local loads the outer skin 12, which can lead to bulges if the same is only about 2.5 mm thick. Should this be entirely are prevented, depressions are formed in the core 11 during its manufacture, into which the fiber ribbons 15 are inserted so that their surface is practically in a wrapping line with the other areas of the core 11 lie.

Instead of fiberglass fabrics, fabrics made of carbon, kevlar, can also be used or aramid can be used. These types of fibers lead to an even greater stiffening; however, they are more expensive than Fiberglass.

Instead of unidirectional fibers, fiber fabrics can also be used in which the fibers have no preferred direction exhibit. It should be noted, however, that a sailboard is considerably longer than it is wide. A stiffening is therefore especially required in the longitudinal direction. This stiffening straight in one direction can be combined with a unidirectional Achieve optimal material. To achieve the same rigidity

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with a non-directional material, it is to be used in larger quantities, which increases the weight of a sailboard leads.

In order to achieve a stiffening exactly in the longitudinal or direction of travel 16, it is sufficient to use unidirectional fiber ribbons 15 or Lay flat fabrics with the grain in the direction of travel 16. It is, however, the case that the board 10 is also subject to torsional loads is subject to the longitudinal direction. In order to increase the torsional rigidity, it is necessary that To lay slivers 15 transversely to the direction of travel. This transverse position has up to an angle of 45 ° with respect to the Direction of travel 16 sense. Will be unidirectional slivers at an even larger angle with respect to the direction of travel laid, the transverse rigidity is increased more than the longitudinal rigidity, which is actually to be improved.

Instead of individual slivers I5 on the top and the To lay the underside of the core 11, it is also possible to bandage the core with fiber tapes, for example are wrapped around the core at an angle of about 20 ° to the left and right of the direction of travel. It is also possible to use tapes laid directly in the direction of travel and additional tapes running at an angle. Advantageous is to reinforce the lower side more than the upper. This is because bending loads essentially exist to the effect that the driver loads the middle of the sailboard 10 and this just at his front and his rear end is supported on wave crests, while the middle is above a wave trough. Then the bottom stressed on train. A correspondingly large burden

J50 of the top on pull does not occur. The torsional load on the other hand, it is the same on the underside and on the top.

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It is therefore advantageous to use bands to increase the torsional stiffness to be laid symmetrically on the top and bottom, but additional on the bottom Laying tapes with the pasers in the direction of travel in order to increase the bending stiffness in the longitudinal direction.

Sailboards according to the invention can be manufactured in any desired manner. The inventive method is however, it is particularly advantageous because in a single manufacturing device in directly successive work steps Prefabricated half-shells are connected to a prefabricated core and by connecting in a hot state at the same time all adhesive connections are made. It is possible to heat separately prefabricated half-shells, or, as stated above, the half-shells in the manufacturing device for the board in an upstream Manufacturing step can be generated. The structure according to the invention but instead of half-shells for the outer skin, z. B. produce with a sprayed-on outer skin.

It is also advantageous to use a core with longitudinal grooves which run essentially in the direction of travel. In these The adhesive runs in grooves from the adhesive bead 25 when it is heated, for which a correspondingly large amount of adhesive has to be applied. In the case of four bands 15 as shown in the figures, each approximately 8 cm wide, the grooves run in the direction of the band. The grooves are about 5 mm deep and about 20 mm apart. The glue in the grooves leads to one special solid connection between core and fiberglass fabric, be it in the form of a tape or mat.

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Claims (12)

■::. . : 'BIND-Οθβ _- ..:' '-' ■ 'n.y. Binder CLAIMS Sailing board and process for its manufacture 1. Sail board (10) with - a smooth outer skin (12) made of plastic, - An inner filling which is closely enclosed by the outer skin and has a core (11) made of foam, and - An adhesive layer (14) between the outer skin and the inner filling, marked by - A fiber insert (15) between the outer skin (12) and the core (11) which, together with the core, forms the inner filling forms, and - A bond (19) between the fiber insert and the foam core. 2. Sailboard according to claim 1, characterized in that the adhesive layer (14) between the outer skin (12) and the paving insert (I5) through the material of the core and the fibers each well-wetting adhesive is formed, which is also at least a few millimeters into the cavities between the foam grains of the core (11) has penetrated, that is, at the points of the fiber insert, the bond between the fiber insert and the foam core is also produced. 3. Sailboard according to claim 1, characterized in that g e that the fiber core (I5) is a unidirectional fabric that with the fibers in Direction of travel (16) is relocated. H.J. binder 4. Sailboard according to claim 1, characterized in that the fiber insert (15) is a fiberglass fabric. 5. Sailboard according to claim 1, characterized in that g e - indicates that the fiber core is formed by unidirectional fiber ribbons (15). 6. Sailboard according to claim 5, characterized in that that the slivers (I5) obliquely to the direction of travel (l6) at a maximum of 45 ° to this are relocated. 7. sailing board according to claim 6, characterized in that on the top and there are two bands (15) on the lower side, the two bands on one side close to the front Cross the end of the board and run from the point of intersection to the side edges (18) so that they reaching the edges near or at the rear end (I7) of the board. 8. sailing board according to claim 1, characterized in that g e - the fiber core (I5) is a glass fiber fabric, - The core (11) by foamed polystyrene and - the bond (I9) with a polyurethane adhesive is formed. 9 · Sailboard according to claim 1, characterized in that the outer skin (12) is formed by an acrylic-styrene-acrylic ester (ASA). 10. Sailboard according to claim 2, characterized in that that the core has essentially longitudinally extending grooves into which the adhesive the bond (19) has penetrated. '-'- ■ -' - ■. "--3IND-006 11. A method of manufacturing a sailboard in which - two half-shells (12.1, 12.2) made of plastic for the outer skin (12) of the board (lo) in spaced apart, parallel to each other, - one with an adhesive layer that can be activated by heat (14) coated prefabricated core (11) made of foam in the space between the half-shells is inserted, - and finally the half-shells are joined together including the core, characterized in that - a fiber insert (15) on the prefabricated core (11) is attached and - on this one she herself and the foam core in heated, liquid state well wetting adhesive (25) is applied. 12. The method according to claim 11, characterized in that the half-shells (12.1, 12.2) by heating plastic films and drawing them into mold halves (20) by means of negative pressure and are assembled in half-shells produced in this way by bringing the mold halves together.