The objective of the invention is a bed bottom.

Several materials are used as bottom materials for beds, such as hardboard, compact plywood, which enable the adding of holes. Plywood is formed by attaching several veneer layers to each other by gluing. Bending plywood products are formed by hot-pressing several superimposed veneer layers. It is known, that plywood can be bent in several directions only as very thin layers, when the wood is moistened, and thereafter dried in a heated press mould. Other materials used are detachable lath bottoms, spring mattresses and water beds. A need has arisen to manufacture a uniform bottom by veneering, which better considers the capability of the plywood to form a structural part by combining the flexibility and the thinness of the bed bottom. The inven¬ tion is based on a quite new structure and manufacturing method of a bed bottom.

The DE-patent 2738261 describes a uniform or into several parts divided laminated plywood board. The thickness (strength) of the laminate (board) varies according to the load on different parts of the board. The board is charac- terized in that the plywood board is not equally thick in its whole dimension, and not always one uniform board. Moreover, should be observed, that the plywood board is only laterally curved, i.e. it is substantially equally curved from one edge to the other. By this the board touches the support or the frame from its edge (not the plane surface). The bottom plywood of the publication is laterally divided into strips in several different ways, with the objective to achieve a solution substituting independent laths. The division into strips is made either so that the edge portion of the bottom is whole (uniform) (Fig. 1; 10, 12a) or broken (Fig. 2; 15). This indicates clearly that the bottom plywood of the publication is not intended to be used as the con-

structive part of the supporting structure of the bottom, but as an independent part supported by the bottom frame of the bed. The independence of the bottom board becomes espe¬ cially evident from the description of Fig. 2 on page 10, stating that outer ends of the laths can at the border-area freely extend outward, and that the bottom plywood consists of three different parts A,B,C. Thus the bed bottom present¬ ed in the DE-publication differs substantially to its struc¬ ture and characteristics from the bed bottom according to our invention.

The Fl-patent 62763 describes a bed bottom board, which is a uniform or into several parts divided, laterally curved plywood board. The plywood board is laterally divided into laths. The bed bottom is especially characterized in that, the bottom plywood does not function as a compact, construc¬ tive part of the bottom structure of the bed, but is an independent part of the bed, supported by a separate sup¬ porting structure. This characteristics become evident from page 3 (last paragraph), which states that the board moves independently by means of plastic slides.

The bed bottom according to the invention and its manufac¬ turing method are characterized in what is presented in the claims 1 and 6.

A significant advantage of the invention is, that the bottom of the bed is elastic and at the same time thin. The bottom material itself is made by a fairly simple method. The bottom does not necessarily need any other cover than e.g. an overlay. The board according to the invention is curved (convex) both in the lateral and the longitudinal direction so, that the plywood can be attached to the frame from the not-bending part of the plywood. The invention does not contain any curved edges. The board is uniform. The cupped form of the bottom plywood, being horizontal from its edges, enables the parallel attachment of the plywood to the frame

surface. In other words, so designed, the plywood board functions as a compact, supporting part of the bottom struc¬ ture, and not just as an independent part to be supported separately by the supporting structures, as in the reference publications. The structure enables also a lower structural height than the solutions of the reference publications. The independent bottom boards of the reference publications do not provide equally durable and light structures. The struc¬ ture of the board and the bending form enable the use of the board as the supporting structural part of the bed bottom.

The invention is in detail presented below with reference to the enclosed drawings:

Fig. 1 presents a bed bottom according to the invention and a cross-section of the frame attached thereto; Fig. 2 presents a perspective illustration of a bed fur¬ nished with gables; Fig. 3 presents the bottom frame; Fig. 4 presents the bottom, and

Fig. 5 presents the bed bottom attached to the frame.

Fig. 1 presents a cross-section of the bed bottom. The bed bottom 1 comprises a pre-pressed plywood 2, which is convex in the middle. The plywood 2 is from its edges attached to the bottom frame 4. The plywood edges 5 are from the fixing surfaces parallel with the frame surfaces 6. Fig. 2 presents a perspective illustration of a bed, comprising gables 7, 8 and the bed bottom 1 according to the invention.

Fig. 3 presents a known frame, comprising boards 10, 11 and 12, 13, joined together to form the frame.

Fig. 4 presents the plywood structure 2 according to the invention. The plywood structure is manufactured by cutting the plywood veneers into desired shapes and sizes. All veneer layers are glued and pressed simultaneously against a

hot mould, leaving the edge portions 5 of the veneers as the plane surface, and the middle portions 3 of the veneers adjusting to the predetermined shape of the mould, the so called cup shape, by which each veneer is stretched into its shape in the joint press, and is glued to a plywood. In the plywood, comprising several pre-pressed veneers, is thereaf¬ ter drilled holes, from which slots 9 are cut through the plywood at certain distances from each other to enable bending. The slots 9 are made in the bending portion of the plywood, i.e. the middle portion 3. When finished, the structure 2 is attached to the frame 4 so, that the bossage of the plywood is outward from the frame 4, as illustrated by Fig. 5. The thickness of the plywood could vary e.g. between 5-15 mm, and plywood of 5-9 mm has been found favor- able. Due to the bending, the thickness of the plywood might vary outside these limits. The plywood can have 3-10 layers, e.g. 4-6 layers, depending on the thickness of the veneer. The slots 9 can start from the edge portion of the plywood and end at the same.

The slots can be at equal distances from each other or e.g. farther away in the middle than at the edges, etc. The width of the slots as well as the intermediate portions of the slots can vary. The plywood can be build separately for children and adults e.g. according to the weight. The ply¬ wood is so formed, that the middle portion of the bottom is substantially highest/deepest in the middle line of the bed. In the method, glue is applied to the veneer, whereafter the next veneer is attached on top of the same, and this is repeated as many times as necessary. The so formed pack is taken into a hot mould for bending and pressing. Because the interspace of the veneers are not yet completely glued together, the veneers can move in relation to each other, and so adjust to the shape of the mould, and attach to each other to provide a plywood of desired shape.

The invention has been above described with reference to

only one of its favorable examples of embodiment. The inven¬ tion is not to be considered as so limited, but several modifications within the scope of the inventive idea charac¬ terized by the claims are feasible.