EP0462597B1 - Construction element composed of a wooden part and a part of synthetic material - Google Patents

Abstract

In a construction element composed of a wooden part and a part of synthetic material, the wooden part has, on at least one side, at least one recess into which the part of synthetic material is injection moulded. In this case, the at least one recess penetrates so deeply into the wooden part that a self-supporting bond between synthetic material and wood results. In a method for manufacturing these construction elements, a wooden bar (1) is provided, at its end face, with at least one deep, approximately roof-like notch (3, 4). The wooden bar (1) is then, at least with its notched end face (2), placed into a mould (7) and finally a synthetic material entering into an adhesive bond with the wood is injection moulded into the mould (7) and the notches (3, 4). <IMAGE>

Description

The invention relates to a construction element with a wooden and a plastic part.

From DE-GM 89 09 880 a construction element made of a wooden stick is known. which is provided with tines on one end. hereinafter referred to as zincing. Bores are arranged between the teeth. going beyond the depth of the tine. penetrating into the depth of the wooden part of the element to accommodate reinforcing bars, which are necessary for establishing a secure connection between the plastic part and the wooden part of this element. The wooden stick can consist of a long wood or of long wood glued together. The individual tines of the tine can be pyramid-shaped. This - the usual finger jointing between wood and wood - connection between plastic and wood is not or only partially suitable or applicable, especially in the open air. since the different material behavior of wood and plastic in the short transition area between the wood and plastic part cannot be compensated or - more precisely - does not compensate. The reinforcing bars connecting wood and plastic can be made of GRP (= glass fiber plastic). Steel or other reinforcing elements or bars exist. The reinforcements protruding freely from the plastic part of the structural element serve for connection to other components. for example on concrete foundations.

The known construction element has proven itself to a limited extent, but is both in view of its usability outdoors. as well as for reasons of increasing the static load capacity. and also for reasons of durability. and can also be improved for reasons of simplifying the production process.

From DE-A-38 28 476 (Fig. 9) it is known to restore the load-bearing capacity of a damaged wooden beam by removing the damaged area, drilling out the healthy material, inserting reinforcement into the hole and then using a potting compound Filled hole and the removed area of the beam is replaced by the hardened casting compound.

The aim of the invention is to create a stable construction element with a wooden and a plastic part. Here an improved anchorage between wood and plastic should be guaranteed.

This goal is achieved by a construction element according to claim 1.

The special idea of the invention is to create a self-supporting, stable wood-plastic connection. The "self-support" of the connection is achieved by a sufficiently large depth of penetration of the recess - or of the plastic - into the wooden part.

According to the invention, the recess is formed by intersecting incisions. Such a recess is easy to manufacture on the one hand and on the other hand further optimizes the strength of the connection.

The wood is immobilized in the course of the long transition area from wood to plastic in that the proportion of the wood volume decreases slowly and gently and continuously. while the volume proportion of the plastic increases in the same way, thus ensuring a smooth transition from wood to plastic. a kind of stress-free transition from one of the different materials to the other. The end grain / end grain is therefore simultaneously protected against the absorption of moisture, other weather influences, road salt broth and pest infestation, since each individual fiber and capillary is individually packed and firmly bound.

Both the immobilization of the wood and the stability and strength of the transition from the wooden to the plastic part can be regulated and adjusted to the respective strength requirements and the type of wood to be used by varying the shape and depth of the recess.

Larch works e.g. extremely strong and requires particularly deep recesses. Less deep recesses are sufficient for spruce. Glued wood behaves "benevolently" than solid. non-glued wood. Glued wood or glulam therefore requires less deep recesses.

A particularly firm connection is achieved in that the recess tapers in the direction of penetration, in particular if the course of penetration of the recess extends predominantly at a more or less acute angle to the wood fiber. The diagonally cut fibers and capillaries offer the plastic optimal conditions for both cohesive and adhesive, stable connection with the wooden part.

The recess preferably tapers very gently, so to speak gently. As a result, a smooth transition between the different working materials is achieved without the need for additional reinforcements in the boreholes of the wooden part.

If at least one anchoring element is anchored in the plastic part without penetrating into the wooden part (claim 2), the construction element can be connected particularly easily and well to other construction parts.

In a particularly preferred embodiment the recess is deeper than the largest width of the wooden stick. in particular approximately equal to twice the width of the wooden stick (claim 3). A construction element in the form of a wooden stick is a common one. universally usable component. It is a good idea. that the recess tapers like a roof, in particular in such a way that its ridge runs parallel to a length of wooden stick (claim 4). Functionality and simple manufacturability are further perfected. A ridge provides a functional, clean finish to the recess.

A usable artificial cleat part preferably consists of a two-component reaction resin. which penetrates into the texture of the wooden part in the liquid phase. This makes the connection extremely resilient and the construction element remains stable in the long term (claim 5). This effect reinforces the immobilization of the wood. An area of pure wood is followed by a transition area in which plastic and wood mix together. The proportion of wood decreases almost continuously in the direction of the plastic section. until an area of pure plastic is reached. The wood is progressively immobilized by this further "gentle" transition.

Anchoring elements are guided more securely. if the plastic part is designed as a plastic block protruding from the recess (claim 6). The entire end face is preferably covered with plastic. also then. if the recesses only extend over part of the end faces. The entire end face is then protected against pest infestation and weather conditions. Toxic wood preservatives are no longer necessary.

The anchoring elements protrude from the plastic part for easier connection to other components. The anchoring elements are in particular pin-shaped or spherical (claim 7). As anchoring elements e.g. Rods (e.g. made of glass fiber) are particularly suitable. Ropes can also be used for special requirements. Fibers, hooks. Joint connections and the like be used. Such anchoring elements are e.g. advantageous for connecting the construction elements to one another.

Construction elements according to the invention are available inter alia. preferred for the construction of stable scaffolding structures. E.g. Wooden rod-like elements provided on both sides with plastic connections according to the invention and with anchoring elements. complicated constructions such as Hall roof scaffolding or the like can be realized.

For this purpose, construction elements with external threaded rods are particularly suitable as anchoring parts. An additional metal ball with several internal threads as a connecting part enables the construction of star-shaped or "atomium-like" constructions.

For wooden parts with a larger cross-section. especially for rectangular cross sections with very different edge lengths. Repetitions of the recesses can be advantageous. Here, e.g. intersecting incisions or simply tapered sections are repeated. Repeated recesses increase the strength.

Another object of the invention is. to create a procedure. that allows the production of construction elements according to the invention in a simple manner.

This is achieved with the method characterized in claim 8. The process is straightforward and does not require much effort.

A preferred embodiment of the construction element according to the invention combines e.g. The following features: The construction element consists of a wooden stick with recesses on one side. into which a plastic block comprising anchoring elements is cast. The recesses are of two roof-like. intersecting incisions formed on the end face, the anchoring elements and the plastic block extend into the incisions, and matrix-forming fillers are embedded in the plastic block. The roof-like and intersecting incisions not only allow large-area connection of the plastic block to the wooden stick. they also enable a particularly favorable transfer of forces and moments between the wooden stick and the plastic block, because practically all fibers of the wooden stick are connected to the plastic block over a large area. For this purpose, the incisions should extend in particular over a length of the wooden stick. which is larger than the greatest width of the wooden stick. The incisions should preferably extend over a length. which corresponds to twice the width of the wooden stick. The ridges of the incisions should extend parallel to the sides of the wooden stick.

The anchoring elements can extend into the incisions. On separate. the holes receiving the anchoring elements on the end face of the wooden rod can be dispensed with. For the transmission of forces and moments, it is favorable if the anchoring elements are arranged in the outer areas of the incisions.

The matrix of the fillers stabilizes the plastic and improves the anchoring of the plastic to the wood as well as the anchoring of the anchoring elements in the plastic. Preferably, the packing should be designed so that they can get caught with each other and thus can also transmit tensile forces. In particular, the matrix can consist of packing elements in the form of tetrapods.

A preferred method for producing this structural element is characterized in that a wooden rod is provided on the end face with roof-like, intersecting incisions, that the wooden rod is placed at least with its incised end face in a form that anchoring elements reaching into the incisions are inserted into the mold that the mold space and the incisions are filled with matrix-forming moldings and that the mold and the incisions are then cast with plastic. The matrix (or reinforcement) can be adapted to the respective technical and statistical requirements. Appropriate design means hardness or softness, UV stability, as well as adjustable electrical and thermal conductivity. A thermosetting, solvent-free reaction resin or epoxy resin is preferably used as the plastic.

The incisions can be made by sawing or milling. In order to enlarge the surface in the area of the incisions, the inner surfaces of the incisions can be sandblasted. This also has the advantage that the softer wood components (summer rings) are removed, while the hard wood components (winter rings) remain as ribs or the like and are encased in plastic.

Depending on the type of plastic to be used for the plastic block, it may be expedient to keep the molding space at a temperature suitable for casting the plastic. This is especially true when two-component reactive resins are used. Hot air can be blown into the mold space to heat and maintain the temperature. If the plastic is then poured into the heated mold space, it is evenly and bubble-free distributed around the packing elements located there. After the plastic has cooled and hardened, the construction element can be removed from the mold. This process has also been successfully carried out using a microwave and the corresponding microwave device.

The construction element can be manufactured using customary shapes. It is expedient to use molds, one end of which has guide openings for the anchoring elements, so that the anchoring elements can be introduced into the mold and into the incisions in the longitudinal direction of the wooden stick. This can be done with a lost molding that has guide openings. The wooden bar with recesses can be turned into a U-shape Cardboard are inserted, which has release agents on the inside. One end remains open. This end is closed with a felt plate. The felt plate has holes and possibly other release agents. Through the holes, anchor and anchoring elements such as glass fiber rods, threaded rods, fiber bundles, ropes, profiles or the like can be be led into the casting room and poured out. The felt plate reliably closes the encapsulation area even in the case of heat and high viscosity. Instead of this, it is also possible to work with a prefabricated plastic block which has guide openings and which is then part of the plastic block on the finished construction element.

The invention can be combined with known devices; e.g. the rods can also be anchored in the wood, although this is not necessary to achieve sufficient strength.

Fig. 1

eine Draufsicht auf eine geöffnete Form zur Herstellung eines Konstruktionselementes aus einem Holzstab und einem an eine Stirnseite anschließenden Kunststoffblock;

Fig. 2

eine Stirnansicht des Holzstabes;

Fig. 3

eine Draufsicht auf das fertige Konstruktionselement:

Fig. 4

in kleinerem Maßstab eine Draufsicht auf ein anderes Bewehrungselement.

In the following an embodiment of the invention shown in the drawing is explained; show it:

Fig. 1

a plan view of an open mold for producing a construction element from a wooden stick and a plastic block adjoining an end face;

Fig. 2

an end view of the wooden stick;

Fig. 3

a top view of the finished construction element:

Fig. 4

on a smaller scale a top view of another reinforcement element.

In the drawing, the front end of a wooden stick 1 can be seen, which can be in one piece or can consist of several wooden sticks glued together. A The end face 2 of the wooden stick 1 has two intersecting cuts 3, 4, the ridges 5, 6 of which extend parallel to the sides of the wooden stick 1 with a square cross-section. The length of the incisions 3, 4 is approximately twice the width of the wooden stick 1.

The wooden stick 1 is placed in a mold 7, the cross section of which corresponds to the cross-sectional shape of the wooden stick 1. In the embodiment shown, the mold 7 is closed at the end facing away from the wooden rod 1 with a lost molded part 8 which has guide openings for anchoring elements 10. The guide openings 9 are arranged such that the anchoring elements 10 introduced thereby can extend in the outer regions of the incisions 3, 4 to close to their ridges 5, 6. In Figure 2, the arrangement of the anchoring elements 10 is indicated by dash-dotted lines.

Before the wooden stick 1 is inserted into the mold 7, the inner surfaces of the incisions 3, 4 are sandblasted or brushed with a steel brush, the softer wooden components (summer rings) being removed and the harder components (winter rings) remaining like ribs.

After the wooden stick 1 is inserted into the mold 7, the anchoring elements 10 are inserted into the mold through the guide openings 9 until they extend as far as possible into the incisions 3, 4. Then fillers 11 are filled into the mold 7, which form a matrix. This matrix is indicated by hatching in FIG. 1. The shape of the filler 11 is in itself arbitrary if it is only suitable to form a matrix which, to a certain extent, can also transmit tensile forces. The filling elements 11 can preferably consist of tetrapods.

After the plastic has cooled and hardened a plastic block 12 firmly connected to the cut end face 2 of the wooden stick, over which the free ends 13 of the anchoring elements 10 protrude. These free ends 13 are connected to other components or poured into a concrete foundation. It goes without saying that the arrangement and number of the anchoring elements 10 can also be different from that shown in the exemplary embodiment.

FIG. 4 shows an anchoring element, the elements of which are designed as flat bars 14. The planes of the flat bars 14 are perpendicular to one another. The flat bars 14 have tapered ends which engage in the incisions 3, 4. At the other ends, the flat bars 14 are combined to form an anchoring part 15, which protrudes beyond the plastic block 12 and is preferably intended for anchoring the structural element in grown or loose soil. In the area of the anchoring part 15, the flat bars 14 are united with one another by stiffeners 16 arranged perpendicular to the plane of the flat bars. The anchoring element can be made of metal or fiber-reinforced plastic.

Any material can be used for anchoring the part that has a tensile and / or pressure absorption capacity that corresponds to the respective technical and / or static requirements.

Claims (8)

1. Structural element consisting of a wooden and a plastic part. The wooden part being shaped to form a rod (1) with at least one recess on at least one front end (2) and with the plastic part being poured into the recess whereby a self-supporting link is generated between the plastic part (12) and the wooden surfaces of the recess and characterized in that the recess consists of roof-shaped tapered and intersecting mortises (3, 4) into which the plastic part is poured.
2. Structural element as per claim 1) characterized in that at least one anchoring element (10) is anchored in the plastic part such that it does not penetrate into the wooden part.
3. Structural element as per one of the aforegoing claims characterized in that the recess is deeper than the greatest width of the wooden rod (1), and in particular, approximately equal to double the width of the wooden rod.
4. Structural element as per one of the aforegoing claims 1) to 3) characterized in that the ridge of the recess (5, 6) extends parallel to one longitudinal side of the wooden rod.
5. Structural element as per one of the aforegoing claims characterized in that the plastic part consists of a two-component thermosetting resin that, while in its liquid phase, penetrates the texture of the wooden part.
6. Structural element as per one of the aforegoing claims characterized in that the plastic part is shaped such that it projects as a plastic block (12) from the recess.
7. Structural element as per one of the aforegoing claims characterized in that the anchoring elements (10) project from the plastic part and particularly in that they are pin or ball-shaped.
8. Process for producing a structural element specifically in accordance with any one of the aforegoing claims characterized in that a wooden rod (1) is furnished with deep roof-shaped tapered and intersecting mortises (3, 4) and the wooden rod (1) is inserted at least with its recessed front end (2) in a form (7) and that form (7) and the recesses (3, 4) are finally poured with a plastic material that enters into an adhesive connection with the wood.

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