Apparatus and method for surface treatment of a body

Abstract

 An apparatus (1) and a method for the surface treatment of a body (3), the apparatus (1) including: an advancing means (5) to produce relative movement between the body (3) and the apparatus (1); at least one applicator (7) which is arranged to apply a surface treatment substance to the body (3); and at least a curing device (11) to induce or accelerate curing of the surface treatment substance which has been applied to the body (3), the apparatus (1) further including a texture-producing device (9) which is arranged in a portion between the applicator (7) and the curing device (11) to produce a texture (4) in the surface treatment substance before this hardens.

Description

[0001] The present invention relates to an apparatus and a method for the surface treatment of a body. More particularly, it relates to an apparatus for and a method of applying a surface treatment substance to a body, the apparatus including: an advancing means to produce relative movement between the body and apparatus; at least one applicator which is arranged to apply a surface treatment substance to the body; and at least one curing device to induce or accelerate curing of the surface treatment substance which has been applied to the body.

[0002] In particular, but not exclusively, the invention is directed towards the surface treatment of plate-form bodies such as wood-fibre-based boards for use as internal wall or ceiling panelling in buildings. For that reason, the invention will be directed in particular towards such boards, but it will be understood that the apparatus and the method could also be used for bodies of another shape and with another area of application.

[0003] In the building market there has been, in recent years, a considerable demand for building boards whose surfaces have been treated with paint, for example, so that further surface treatment will not be necessary after mounting. The building boards are typically so-called wood-fibre boards but may also be made of another material.

[0004] The reasons for the increased demand are probably several, but, in short, the most important ones can be summed up into quicker completion of a building project and a more attractive end result.

[0005] There has been a particularly big demand for boards which are formed with a surface that simulates wood panel. This is achieved by embossing the surface of the building boards to provide indentations or beads that extend parallel to the longitudinal axis of the board.

[0006] A visual drawback of such painted wood-fibre boards is that the face portions will be too different from the texture that appears naturally when wooden panels are painted with a brush.

[0007] To simulate such a "brush-painted" appearance, it is known to provide scratches in the longitudinal direction of the surface of the board before applying paint or another surface treatment substance. The scratches are thus to simulate traces from bristles of a brush.

[0008] A person skilled in the art will know that in the industrial production of painted wood-fibre boards the boards are carried through a cure-promoting device immediately after paint has been applied to the surface. In addition to enabling stacking of the boards in height as soon as they come out of the curing device, it is done to effect or accelerate setting of the surface treatment substance before this fills the stripes completely and thereby ruins the desired effect. As a cure-promoting means it is normal to use an oven, IR or UV radiation, for example.

[0009] The stripes are typically provided by means of a grinding means such as grinding paper or another surface-rubbing means, or a milling device.

[0010] There are several drawbacks related to the said method of providing a brush-painted appearance.

[0011] The method is expensive as it requires grinding machines and considerable amounts of grinding means, such as sand paper. Besides, sand paper will wear, which gives large variations in depths and extents of the stripes.

[0012] It is common for wood-fibre boards to be made with an outer layer which is harder than the core portion of the board. By rubbing or grinding the surface, the outer layer is damaged. This may ruin some of the properties of the board. Besides, a board with a rubbed surface may absorb more surface treatment substance, which will, in turn, require larger consumption of surface treatment substance and thereby lead to increased production costs.

[0013] As the surface is being ground, particles will be released in the form of grinding dust. For work-environmental reasons, among other things, this will require air suction. In addition, dust remaining on the surface of the board should be removed before a surface treatment substance is applied, in order to achieve the desired finish.

[0014] The depth of the scratches that must be produced in the surface depends on the end result desired and on how many layers of surface treatment substance are applied. The more layers, the deeper scratches are required.

[0015] However, one of the largest drawbacks of the above-mentioned prior art relates to the end result; boards that are provided with grooves produced to simulate a joint region of a tongue-and-groove joining of wooden panels, for example, will not be affected by the grinding means. For example, grinding paper will not be able to penetrate into the grooves unless customized grinding machines and grinding papers are used. In addition, beads or elevations, if any, will be subjected to a disproportionately powerful grinding action while, at the same time, transitions between the beads and the face portions of the board will not be affected by the grinding paper. Thus, the result will be that portions of the board will appear without the desired brush-painted surface.

[0016] The invention has for its object to remedy or reduce at least one of the drawbacks of the prior art, or at least to provide a useful alternative to the prior art.

[0017] The object is achieved through features which are specified in the description below and in the claims that follow.

[0018] According to a first aspect of the present invention, an apparatus for the surface treatment of a body is provided, the apparatus including: an advancing means to produce relative movement between the body and the apparatus; at least one applicator which is arranged to apply a surface treatment substance to the body; and at least a curing device to induce or accelerate curing of the surface treatment substance which has been applied to the body, the apparatus further including a texture-producing device which is arranged in a portion between the applicator and the curing device to produce a texture in the surface treatment substance before this hardens.

[0019] The desired texture is thereby produced in the surface treatment substance itself, while, at the same time, the body which is being treated has no damage done to its surface.

[0020] The texture-producing means is preferably formed by a plurality of flexible, elongated and mutually independent elements. The texture-producing means may be brought to bear both against smooth board portions and against indentations and elevations at the same time. The entire board portion may thereby appear with a surface treatment substance that has been affected by the texture-producing means.

[0021] Additional features of the invention will appear from the dependent claims 2-8.

[0022] In a second aspect of the invention, a method for the surface treatment of a body is provided, wherein the body is carried on a track and is having a surface treatment substance applied to it by means of an applicator and is then carried into a curing device for curing of the surface treatment substance to be induced or accelerated, a texture-producing device being brought into contact with the surface treatment substance after it has been applied to the body. It is an advantage if the texture-producing device is brought into contact with the surface treatment substance before the body is carried into the curing device.

[0023] In what follows is described an example of a preferred embodiment which is visualized in the accompanying drawings, in which:

Figure 1

shows a principle drawing, in a perspective view, of an apparatus according to the present invention for producing a texture in a surface treatment sub- stance after this has been applied to a board; and

Figure 2

shows a principle drawing, in a side view, of sev- eral apparatuses placed in series.

[0024] Like or corresponding elements are indicated by the same reference numerals.

[0025] In the figures, the reference numeral 1 indicates an apparatus according to the present invention which is arranged for surface treatment of boards 3 which are arranged one after another on an advancing means in the form of a conveyor belt 5.

[0026] For reasons of clarity, the boards 3 are shown with a planar surface but might just as well be provided with grooves and/or beads to resemble joined wooden panels.

[0027] The necessary supporting and propelling means of the conveyor belt 5 are not shown but are of a kind known per se. The moving direction of the conveyor belt 5 is shown by arrows V.

[0028] The individual board 3 is carried between the conveyor belt 5 and an applicator 7 for a surface treatment substance, the applicator 7 being formed, in the embodiment shown, by a roller which extends transversely to the longitudinal direction of the board 3.

[0029] In an alternative embodiment, the surface treatment substance may be applied to the board 3 by means of a spraying plant, not shown.

[0030] The roller 7 is of such a kind that it moulds to the surface texture of the board 3 in order thus to apply a surface treatment substance to the entire board, including possible grooves. A type of roller that has proved suitable for the purpose is made of so-called "moss rubber" which is relatively porous and flexible.

[0031] The apparatus 1 may be provided with several rollers (not shown) to enable switching from one colour to another, for example, without unnecessary stops in the production. Of course, with such an arrangement, only one roller will be moved against the board 3 at a time.

[0032] In what follows, for simplicity, the surface treatment substance will be referred to as paint, even though other surface treatment substances such as varnish, oil, wax or other suitable substances could also be used. This will be explained in further detail in the discussion of figure 2.

[0033] The roller 7 is supplied with paint in a manner known per se, by means of means not shown. However, this will be known to a person skilled in the art.

[0034] As soon as an even layer of paint has been applied to the board 3 by means of the roller 7, the board 3 is advanced by means of the conveyor belt 5 towards the right in figure 1, to a brush whose bristles bear against the surface of the board 3 to produce the desired texture 4 (shown in broken lines in figure 1) in the paint. The board 3 is advanced into a curing device 11.

[0035] In the embodiment shown, the texture-producing device 9 extends transversely across the entire board 3 relative to longitudinal direction of the board 3.

[0036] In one embodiment (not specifically shown), the texture-producing device 9 is divided into several individual portions. Some or all of the individual portions may have different texture-producing effects. For example, the thickness and/or rigidity between some of the individual portions of the texture-producing device may be different. They may also be arranged to be adjusted individually in order thereby to exert different pressures against the board 3. One and the same board 3 may thereby get different paint textures in its transverse direction.

[0037] The curing device 11 is of a kind known per se and may be based on heat, like for example, but not limited to, a so-called convection dryer, and/or radiation such as IR or UV light (infrared radiation and ultraviolet radiation, respectively). The choice of type of curing device depends on the type of surface treatment substance used, among other things. The distances between the roller 7, the texture-producing device 9 and the curing device 11 are arranged to be adjustable. In figure 1 this is shown in principle by the roller 7 and the texture-producing device 9 being attached to respective, movable supporting devices 12. Said adjustment may be necessary to achieve a desired degree of merging of the "tracks" imparted to the paint by the texture-producing device 9 before the paint sets. Thus, the distance depends on the rate of advancement of the board 3 through the apparatus 1, on the viscosity of the paint and on the temperatures of the board 3 and the paint.

[0038] In one embodiment the distance is arranged to be controlled automatically, depending on the rate of advancement of the board 3 through the apparatus 1 and possibly on other parameters such as temperature and paint viscosity.

[0039] Figure 2 shows a principle drawing, in a side view, of a production line in which five apparatuses 1 are arranged in series, and in which boards (not specifically shown in figure 2) are carried through the apparatuses 1 by means of a conveyor belt 5. In the embodiment shown, a cooling device 13 is arranged in addition behind the fifth and last curing device 11. The purpose of the cooling device 13 is to reduce the heat which has been introduced into the boards through the curing devices.

[0040] In the embodiment shown, a texture-producing device 9 is placed between each roller 7 and curing device 11. It will be understood, however, that in an alternative embodiment it is conceivable for one or more of the texture-producing devices 9 to be omitted, but there must be at least one. However, trials have surprisingly shown that the best result is achieved by arranging a texture-producing device 9 between each roller 7 and curing device 11.

[0041] The series of apparatuses 1 that is shown in figure 2 enables the application of five layers of surface treatment substance. For example, the first apparatus 1 in the series could be used to apply a primer to the board; the second, third and fourth apparatuses in the series paints of desired colours, and the fifth and last apparatus 1 in the series a protective varnish. A person skilled in the art will understand that a production line may consist of more or fewer than the five apparatuses 1 that are shown in the exemplary embodiment.

[0042] Thus, the present invention provides an apparatus and a method which possess substantial advantages and solves several of the drawbacks related to the apparatus and method which are used to produce a desired brush-painted texture on a wood-fibre board.

Claims

1. An apparatus (1) for the surface treatment of a body (3), the apparatus (1) including: an advancing means (5) to produce relative movement between the body (3) and the apparatus (1); at least one applicator (7) which is arranged to apply a surface treatment substance to the body (3); and at least a curing device (11) to induce or accelerate curing of the surface treatment substance which has been applied to the body 3), characterized in that the apparatus (1) further includes a texture-producing device (9) which is arranged in a portion between the applicator (7) and the curing device (11) and at a distance from the curing device to produce a texture (4) in the surface treatment substance before this hardens.

2. The apparatus in accordance with claim 1, wherein the applicator (7) includes a roller or a spraying device.

3. The apparatus in accordance with claim 1, wherein the curing device (11) is formed by one of or a combination of a heating device, an IR radiation device and/or a UV radiation device.

4. The apparatus in accordance with claim 1, wherein the texture-producing device (9) includes a plurality of flexible, elongated elements.

5. The apparatus in accordance with claim 4, wherein the elements are fibres.

6. The apparatus in accordance with claim 4 or 5, wherein the texture-producing device (9) is divided into several individual portions.

7. The apparatus in accordance with claim 1, wherein the apparatus (1) includes alternately two or more applicators (7) and curing devices (11) placed in series, the texture-producing device (9) being arranged at least between one of the applicator (7) and the curing device (11).

8. The apparatus in accordance with claim 1, wherein the surface treatment substance is one of or a combination selected from the group consisting of a paint, a varnish, a wax, an oil.

9. A method for the surface treatment of a body (3), in which the body (3) is carried on a track (5) and is having a surface treatment substance applied to it by means of an applicator (7) and is then carried into a curing device (11) for curing of the surface treatment substance to be induced or accelerated, characterized in that a texture-producing device (9) is brought into contact with the surface treatment substance after this has been applied to the body (3).

10. The method in accordance with claim 9, wherein the texture-producing device (9) is brought into contact with the surface treatment substance before the body (3) is carried into the curing device (11).

Drawing