RS51078B - PROCEDURE FOR CORRECTING FLOOR PANEL WITH COMPRESSED EDGE - Google Patents

Abstract

Floorboards consisting of a core (30) and a surface layer (31) with curved edge portions (20), which are formed by a compression of the core.

Description

Technical field

[0001] This invention relates in a general sense to floorboards, which have a core based on wood fibers, a surface layer and compressed curved edge parts. In more detail, the present invention relates to interlocking floor panels with compressed edge portions located below the panel surface. The present invention relates to panels with such edge portions and to a process for manufacturing such panels.

Field of application of the invention

[0002] This invention is particularly suitable for use with floating floors, which are made of floorboards consisting of a core based on wood fibers with a surface layer and it is advisable to connect them with a fitting system that is integrated with the floorboard. The floor panel with the mechanical fit system has a fairly advanced edge profile and curved edge pieces are more difficult to manufacture than traditional furniture components. The following description of the state of the art, the problems of the known systems and the aims and characteristics of the present invention will therefore, as a non-restrictive example, be directed above all to this field and in particular to laminate floors with a mechanical fitting system. However, it should be emphasized that the present invention can be used with optional floorboards with optional fitting systems, wherein the floorboards have a core and at least one surface layer and where these two parts can be formed by applying pressure to that surface layer. The present invention can therefore also be applied, for example, to floors with one or more surface layers of wood placed on a wood fiber core. This invention can also be used with building panels, i.e. wall panels, strips for ceilings and floors such as expansion profiles, transition profiles or end profiles.

Definition of certain terms

[0003] In the text that follows, the visible surface of the installed floor plate is called the "front side", while the opposite side is called the "back side". "Horizontal plane" refers to the plane that runs along the outer flat portions of the surface layer on the face. "Vertical plane" refers to a plane that is at right angles to the horizontal plane and to the outer edge of the surface layer. "Up" means toward the front, "down" means toward the back, "vertical" means parallel to the vertical plane, and "horizontal" means parallel to the horizontal plane.

[0004] "Edge part" means the part of the edge that is below the horizontal plane. "Floor surface" refers to the outer flat portions of the surface layer along a horizontal plane. "Edge surface" means the surface of the edge part. "Fixing system" refers to the means of connection by fitting, which mutually connect the floor slabs vertically and/or horizontally. "Mechanical fitting system" means that joining is possible without glue.

Information on the invention, state of the art and problems related thereto

[0005] Laminate floors and other similar floorboards are made of one or more top layers of decorative laminate, decorative plastic material or wood veneer, a central core of wood fiber-based material or plastic material and, as recommended, of a lower balance layer on the back side of the core.

[0006] Laminate floor material usually consists of a fiber board core with a thickness of 6-9 mm, an upper decorative surface layer of laminate with a thickness of 0.2-0.8 mm and a lower balance layer of laminate, plastic, paper or similar material with a thickness of 0.1-0.6 mm. The surface layer gives the floorboards an appearance and durability. The core provides stability and the balance layer keeps the board flat when the relative humidity (RH) varies throughout the year. The floor slabs are placed so that they float, ie. without gluing, on the existing floor substrate. Traditional hard floor boards with floating flooring of this type are usually connected with glued tongue and groove joints.

[0007] In addition to such traditional floors, floorboards have been developed that do not require the use of glue and are instead joined mechanically with the help of so-called mechanical fitting systems. These systems consist of fasteners that join the panels horizontally and vertically. These mechanical fit systems can be formed by machining the core. Or, parts of the fitting system can be formed from a special material, which is integrated with the floor plate, ie. connected to the floor plate during its construction.

[0008] The most common core material is a high-density fiberboard with good stability, which is usually called HDF - "High Density Fibreboard". Sometimes MDF - "Medium Density Fibreboard" is used as a core. MDF and HDF contain wood fibers, which are combined into a board material with the help of binding agents.

[0009] Laminate floor material, as well as other floor materials with a surface layer of plastic, wood, veneer, cork or the like, are produced in several steps. As shown in Figures 1a-1d, the surface layer and the balance layer are produced in a separate step and are then placed on the core material by, for example, gluing the previously produced decorative layer and balance layer to the fiberboard. Such a manufacturing process is used when the floor panel has a high pressure pressed decorative laminate (HPL) surface which is made in a separate operation where multiple sheets of paper, impregnated with a thermosetting resin such as melamine and/or phenol, are compressed under high pressure and at high temperature.

[0010] Currently, the most common procedure for making laminate floor materials, however, is the direct pressed laminate (DPL) procedure, which is based on a more modern principle in which both the production of the decorative laminate layer and the attachment of the fiber board takes place in just one production step. One or more papers impregnated with a thermoset resin, such as melamine, are placed directly on the board and pressed together under pressure and temperature without any bonding.

[0011] One prior art method is disclosed in document FR 2 846023. In order to achieve a relief effect, straight lines are pressed into the floor element using a relief cube next to each planned parting line. Parting lines are formed in a later step when cutting the floor panels. In a still later step, the fitting means are machined in the area between the stamped straight line and the parting line.

[0012] Another prior art process is disclosed in document US 4 084 996, in which this process begins by assembling several individual layers such as plywood, sawdust and fiber mesh. These layers, together with a thin metal plate, are placed in a hot press where they are exposed to high temperature and pressure, which hardens and adheres the layers and preserves the surface model transferred to the surface by that metal plate. This process is used to produce plywood panels suitable for outdoor use.

[0013] Another prior art procedure is disclosed in document JP-A-2003200405. This document discloses the process by which a covering material is provided for a floor material or the like. The edge part between the top surface and the side surface is pushed with a solid roller to make a bevel cut. Oblique cutting is done after cutting the panels and forming the joining means.

[0014] Drawings 1a-1d show how laminate flooring material is produced according to known technology. As a rule, the above procedures produce a floor element (3 in drawing lb) in the form of a large laminate board, which is then cut into several individual floor panels (2 in drawing lc), which are then machined into floor boards (1 in drawing ld). Floor panels are individually machined along the edges into floor slabs with mechanical edge fit systems. Edge machining is performed in advanced milling machines where the floor panel is precisely positioned between one or more chains and belts or the like, so that it can be moved at high speed and very precisely past a large number of machining motors, which have diamond cutting tools, or metal cutting tools, which machine the edge of the floor panel. By using several machining motors operating at different angles, advanced profiles can be produced at speeds exceeding 100 m/min and with an accuracy of ± 0.02 mm.

[0015] The upper edges of the floor plates are in most cases very sharp and at right angles to the floor surface and in the same plane as the floor surface.

[0016] Recently, laminate floors with decorative grooves or bevels on the edges have been developed, which looks like a real opening or bevel between planks or parquet strips of a solid wooden floor.

[0017] It is known that such edges can be made in several different ways.

[0018] In recent years, laminate floors, which are imitations of stone, tiles and the like, have been used more and more often. It is known that the process used to produce the decorative edges of such floors can also be used to produce edge pieces that look like an opening in solid wood floors. This is shown in drawing 2a and 2b. The starting material is a decorative paper with marked edge parts that is impregnated with melamine resin. In this operation there is an uncontrolled rise. In the next lamination stage, the decorative impregnated paper is placed on the core and the lamination takes place along the embossed metal plate, which forms a recess (20) in those parts of the floor element (3) where the edge parts are to be formed. This is shown in drawing 2a. The result is a floor element (1, 1') whose front side has a concave or convex edge model corresponding to the provided edge parts between the floor plates, as shown in drawing 2b.

[0019] This production process is accompanied by numerous problems, which, in the first place, relate to the difficulty of placing the decorative paper and metal plates in the appropriate position during lamination and the difficulty of placing the floor element and floor panels in the appropriate position during the cutting and machining of the edges that follows. The result is a floor panel with edge sections that exhibit considerable and unwanted variation in structure and design as shown in Figure 2b. Another problem is that this process is only suitable for relief structures that are less than 0.2 mm deep and cannot be made deeper than the thickness of the surface layer. The disadvantage of this procedure is that the edge, although below the floor surface, is sharp and parallel to the surface.

[0020] Drawings 2c and 2d represent another procedure. Decorative edge parts can be made when machining the edges of the floor panel 1, 1'. The lamination and cutting of the floor element (3) can then be done without any special requirements regarding leveling, and there are no lifting problems either. A decorative and recessed edge section can be made by removing part of the decorative surface layer so that the reinforcing layer of the laminate becomes visible (drawing 2d). Alternatively, the core (30) alone may be used to create a decorative recessed edge portion. This is shown in drawing 3a. The surface layer is removed, and the core (30) is exposed in the parts that are to form the decorative edge part (20). A decorative groove can be made on only one edge as shown in drawing 3a.

[0021] The most common procedure is shown in drawing 3b. A part of the edge part of the floor plate (1, 1') is formed as a bevel 20, and this bevel is covered in a special operation with a special material such as ribbon, plastic tape or, it can be painted, printed, etc. Special materials are complicated and expensive to apply and it is not possible to make an edge part of the same design and structure as the floor surface. Such an edge part has significantly lower wear resistance and moisture resistance than the floor surface. This manufacturing process is quite slow and requires several application units to reach the speed of a modern laminate flooring production line.

[0022] The second procedure is shown in drawing 3c. The edge part (20) is formed in a special material, which is pressed or pressed into the groove. This procedure has the same disadvantages as the previously described procedure.

[0023] Drawing 3d shows that the rounded edge part (20) can be produced by a well-known postforming process used for furniture components. The postforming laminate surface (31) of HPL, which is so pliable that it can be formed after the production of the laminate board, can be glued to the already machined floorboard (1). In a second manufacturing step, the edge can be heated and the laminate can be folded and glued around the edge part. This process can be very complicated, expensive and is not used with laminate flooring materials.

[0024] The principles of the present invention are intended for edge parts in building panels, which overcome one or more limitations and disadvantages of the prior art.

[0025] These and other objectives of the invention are achieved by floorboards and production methods having the characteristics specified in the independent patent claims. Dependent patent claims define recommended modes of application of the invention.

Brief content of the essence of the invention

[0026] The main objective of the present invention is to provide floorboards, with curved edge parts made in one piece with the surface layer, which could be produced more efficiently than products currently on the market.

[0027] A further object of the present invention is to provide such panels with edge portions having improved design and wear resistance.

[0028] In order to achieve these objectives, according to the first principle which does not form part of the present invention, a floor panel is provided with a fitting system, a core based on wood fibers and a surface layer placed on the upper side of the core. The outer flat parts of the surface layer form the floor surface and the horizontal plane. A plane, at right angles to that horizontal plane and at the edge of the surface layer, represents the vertical plane. The floor plate has an edge part with an edge surface, which is located below the horizontal plane. The edge surface in the vertical plane is at a distance from the horizontal plane which represents the edge depth and which is greater than the thickness of the surface layer.

[0029] The floor surface and the edge surface are made in one part from the same material. The part of the core in the edge part below the edge surface next to the vertical plane and at a vertical distance from the edge surface has a higher density than the part of the core below the floor surface next to that edge part and at the same vertical distance from the floor surface.

[0030] According to one principle of the present invention, a method for making a floor panel is provided, with a fitting system, a core based on wood fibers and a surface layer placed on the upper side of the core. The outer flat parts of the surface layer form the floor surface and the horizontal plane. The floor plate has an edge portion with an edge surface that is located below the horizontal plane. This procedure consists of the following steps:

• Placing the surface layer on the core to form the floor element.

• Cutting the floor element into floor panels.

• Applying pressure to the surface of the edge part of the floor panel so that the core under the surface layer is compressed and the surface layer permanently bends towards the rear side.

Brief description of the drawing

[0031] Drawings la-d represent different steps of production of the floor board according to the known technology. Drawings 2a-d represent manufacturing processes for forming edge parts according to known technology. Drawings 3a-d represent examples of different ways of manufacturing edge parts according to the state of the art. Figures 4a-d represent the press forming of an edge portion according to the present invention. Figures 5a-c show various features of a convexly curved edge portion according to the present invention. Figures 6a-b represent alternative procedures, this procedure is not part of the present invention. Drawing 7 represents an expansion profile which is not considered part of the present invention.

Figure 8 represents an edge section with a curved edge surface.

Description of recommended methods of application of the invention

[0032] Drawings 4a-4c represent four steps of production of floorboards according to one way of applying the invention. Drawing 4a represents two opposite edges of two essentially similar panels 2, 2' which should be joined together by a mechanical fitting system. The floorboards have a surface layer 31 of, for example, HPL, DPL or wood veneer, a core 30 of HDF and a balance layer 32. As shown in Figure 4b an edge groove 16, 16' is formed on the upper side of the edge and part of the surface layer 31 is removed. This could be done in a separate operation or when cutting the floor element 3 into the floor panels 2. If the surface layer 31 is a laminate, at least one part of the edge groove 16, 16' and the surface layer 31 next to the edge groove 16, 16' should be heated by a suitable heating device H, such as, for example, blowers that emit warm air evenly. The temperature should be higher than 100 degrees Celsius. The recommended temperature is around 150-200 degrees. In many applications, a temperature of around 170 degrees Celsius gives the best results. A normal grade of laminate can be used as the surface layer 31 and no special postforming grade is required. If the surface layer 31 is wood veneer, heating is not required. It is recommended that the floor panel has a reference surface 17, 17' which could be used to accurately position the floor panel when the edge pieces and fitting systems are formed. As shown in Figure 4c, the edge portions 20, 20' are then compressed with a compression tool TO which is, as recommended, heated to a similar temperature as described above. The compression tool TO may be a wheel and/or a pressure shoe or similar profile which, as recommended, matches the desired edge profile. Several tools can be used to create a border in several steps. During compression, the fibers in the core will be permanently compressed, the position of the fibers will in many cases change and the density in the edge portion 20 will increase. The change in the position of the fibers in some core materials is hardly noticeable. The increased density, however, could be measured with great accuracy. The edge section 20 will be significantly stronger than traditional beveled edges in laminate flooring materials. Abrasion resistance will be similar to that floor surface and the visible edge part will have the same design and structure as the edge surface. The upper parts of the core 30 under the surface layer 31, which is impregnated with melamine in DPL floor materials, and with glue in HPL floor materials, support the laminate surface layer 31 during bending and increase the flexibility of the laminate layer. The advantage is that the usual qualities of thermoset decorative laminates, which are quite weak, can be used. HDF is particularly suitable for this type of permanent compression molding according to the present invention, because the fiber structure and binders used in HDF are ideal for this application.

[0033] As shown in drawing 4d, a mechanical fit system with tongue 10 and groove 9 for vertical fit and strip 6 with fit element 8 and fit groove 12 for horizontal fit, could easily be formed and placed with high precision in relation to the compressed edge elements 20, 20'. In this method of application of the invention, the press forming of the edge parts 20, 20' is performed on the floor panel 2, which is then machined into the floor plate 1. The advantage is that the formation of the mechanical fit system can be done with high accuracy and the press forming will not change the dimensions of the profile, which in this embodiment of the invention is mainly the tongue 10 and the groove 9. Of course, it is possible to form the edge parts 20, 20' on the floor plate after edge machining, but this is more complicated and the compression possibilities are less. In most cases, additional machining is required to form the upper outer edge.

[0034] Drawing 5a represents a cross-section of the edge of a panel according to the present invention. In this recommended way of applying the invention, the floor panel 1 has a surface layer 31 of DPL with a surface thickness ST and an outer edge 51. The upper flat part of the surface layer 31 forms a horizontal plane HP and a floor surface 33. A plane at right angles to the horizontal plane and from the outer edge 51 of the surface layer 31, forms a vertical plane VP. The convexly curved edge part 20, which is located below the horizontal plane HP and extends to the vertical plane VP has an edge width EW, measured parallel to the horizontal plane HP and the edge surface 50. The edge part 20 has an edge depth ED measured vertically from the horizontal plane HP, which is equal to the distance SD from the horizontal plane HP to the outer edge 51 on the vertical plane VP. As shown in drawing 5a, the fibers in the edge portion 20 are compressed and the position of the fibers is changed so that they are curved in the same direction as the edge surface 50 of the edge portion 20.

[0035] Several ratios are recommended in order to produce the edge part (20) according to the present invention. • The edge depth ED should be greater than the thickness of the surface layer ST. In an ideal application of the present invention, the edge depth ED should be at least two or even three times greater than the surface thickness ST. This procedure enables the formation of edge portions 20 of edge depth ED that exceed ten times the thickness of the surface ST. • The edge width EW should be greater than the edge depth ED. In an ideal implementation of the present invention, the edge width EW should be at least twice the edge depth ED. • The edge depth ED should be over 0.1 times the thickness of the floor slab T. • The thickness ST of the surface layer 31 should be 0.1 to 0.01 times the thickness of the floor T.

[0036] These relationships could be applied separately or in combination.

[0037] Drawing 5b represents the density profile D in the part (A-A) of the floor plate 1 which is not

compressed, while drawing 5c represents the density profile D in the compressed edge part (B-B) of the same floor slab. Density profiles can be measured extremely accurately with gamma rays. The distance between the measuring points can be as little as 0.04 mm. In this example, the surface layer 31 of the laminate, which is about 0.2 mm thick, has a density of about 1300 kg/m<3>. Below the surface layer 31 is a part of the core 52 which, during direct pressing lamination, is impregnated with melamine and whose density varies between about 1200 and 1000 kg/m<3>. Below this part of the core 52, there is another part 53 whose density is

slightly higher than in the central parts of the core 30. The average density is represented by the line AD. It should be pointed out that compression with board material based on wood fibers always gives an increased density.

[0038] Drawing 5c represents the density profile in the compressed part B-B of the edge part 20. The part of the core 30 in the edge part next to the vertical plane VP and at the vertical distance SD from the surface layer 31, has a higher density D than the part of the core located under the floor surface next to the edge part 20 and at the same vertical distance SD from the surface layer 31.

[0039] This is contrary to the traditional postforming process where the edge part is machined and the surface layer is glued to the core part, which has the same or lower density.

[0040] Drawing 6a represents an alternative procedure for forming the edge part 20 in the floor material DPL. The floor plate 1 is produced with an edge groove 19 under the surface layer 31. The upper part of the edge groove 19 consists of the surface layer 31 and a core part 30. This upper part of the edge groove 19 is folded over the lower part of the edge groove 19 and both parts are pressed and glued. Figure 6b shows that this process can be used to form an edge section of a floor panel which is then machined into a floor slab. Both of these processes are more complicated than press forming because glue and special machining are necessary. This process can partially be combined with press forming and the core can be compressed during bonding.

[0041] Drawing 7 represents an expansion profile 4 with edge parts 20, 20' formed by pressing, according to the present invention.

[0042] Drawing 8 represents a floor plate with edge parts 20 on opposite edges which are curved and where the outer adjacent parts of the edge surfaces 50 are basically parallel to the horizontal plane HP.

[0043] This invention is particularly suitable for the production of laminate flooring materials that look like solid wooden floor strips 5-10 cm wide and where the compressed edge parts are formed only on the longer sides. Such floorboards could also be easily manufactured in different lengths as long press-formed floor panels can be produced which are then machined and cut into floorboards of various lengths.

[0044] A floor consisting of such floorboards will have numerous curved edge portions 20 and can only use a very economical production process such as press forming to achieve production costs that are competitive and lower than similar solid wood floors.

[0045] Press forming is very efficient and can easily reach the speed of modern profile production lines.

[0046] The process of compressing the core with the surface layer of the laminate floor element, floor panel, i.e. floor slab or similar building panel according to the present invention could be used to form relief parts on other non-edge parts.

Claims (5)

1. A method for making a floor panel, with a fitting system, a core based on wood fibers (30) and a surface layer (31) placed on the upper side of the core, wherein the outer flat parts of the surface layer (31) form the floor surface (33) and the horizontal plane (HP), while the floor panel has an edge part (20) with an edge surface (50) located below the horizontal plane, indicated by the surface layer (31) is placed on the core to form a laminate floor element (3), the core (30) being made of HDF, the floor element is cut into floor panels (2), and pressure is applied to the surface of the edge part (20) of the floor panel so that the core under the surface layer is compressed and the surface layer is permanently bent to the rear, with an edge groove (16) being formed on the edge of the floor panel before compression is applied. panel (2), and after applying compression a mechanical fitting system (9, 10, 6, 8) is formed on the edge of the floor panel (2). 2. The method according to claim 1, characterized in that the surface layer (31) consists of paper sheets impregnated with thermoreactive resin. 3. The method according to claim 1, characterized in that the surface layer (31) is wood veneer. 4. The method according to claim 4, indicated by the fact that the edge part (20) is pressed at a temperature of over 100 degrees Celsius. 5. The method according to claim 4, indicated by the fact that the edge part (20) is pressed at a temperature of over 160 degrees Celsius.