The present invention relates to a method for scraping off any surplus material as a continuous process during the feeding of long strip and/or flat-surfaced workpieces, each of which is provided with at least one applied coat of a material present in a plastic condition. The invention also relates to an arrangement for executing the method.

Technical field

The production of high-quality wood products which, for example, are to form part of the surface covering for floors and interior fitting components, involves the elimination of a large number of surface imperfections caused by glued joints, knots, knot holes and the like. It can be assumed that, in conjunction with the production of runs of so-called laminated wood such as laminated parquet boards, a proportion of production may require some form of remedial work.

Description of the prior art

A customary procedure for eliminating the aforementioned surface irregularities involves the manual application of some form of stopper compound. The stopper compound is often mixed with wood meal and/or colouring pigment in order to permit a final result which differs as little as possible from a flawless untreated surface. A spade-like tool made of steel, wood, rubber or similar is normally used in the stopping operation to spread the compound. Stopping must often be performed in a number of directions in order to obtain a good final result. The manual stopping

operation is highly labour-intensive and calls for special treatment of those workpieces which exhibit surface irregularities. Persons involved in manual stopping work easily suffer wear-and-tear injuries.

The work of stopping can also be mechanized, and the compound can be applied with the help of a roller, for example. In this case, however, it is generally difficult to reuse any excess stopping compound.

An improvement in this respect is exhibited by the procedure in accordance with SE 442 832. The product which is to be treated is moved along a track beneath a curtain coater. An excess amount of a fusible powder is applied to the surface for treatment, whereupon the excess powder applied is removed with the help of a scraper device. The remaining powder in the irregularities is subjected to a temporary increase in temperature through radiation or thermal conduction until the melting point is reached. The molten material is then allowed to harden. One disadvantage of the process is that vibration of the surface is often necessary in order for the powder to penetrate into cracks and irregularities. The powder can be ejected once more if the frequency of the vibration is incorrectly adjusted. The powder application process must be repeated, if necessary, in order for the holes to be filled completely.

SuTTimlnσ up of the present invention

The present invention proposes a solution to the problems described above. The invention comprises on the one hand a method for scraping off any surplus material as an uninterrupted process during the feeding of continuous and/or flat-surfaced workpieces, each of which is provided with at least one applied coat of a material present in a plastic condition. The material is scraped off in a

direction cross-wise to the direction of advance of the workpieces, with compression of the material in a direction contrary to the aforementioned direction of advance. The compression of the material is achieved through a taper effect and/or pressure.

The invention also comprises an arrangement for executing the method, according to which the workpieces are so arranged as to be advanced, and a plastic material is so arranged as to be applied as a continuous process. A belt¬ like device is arranged above the surface of the workpiece with the plastic material to be scraped off. The belt-like device is driven in a direction cross-wise to the direction of advance of the workpieces, in conjunction with which it largely forms an angle with the surface of the workpiece.

The method and the arrangement in accordance with the invention permit time-consuming and costly manual stopping to be avoided. Any excess stopping material can be reused. Stopping can be performed in a simple fashion without the need to resort to any form of vibration of the workpiece.

The characterizing features of the present invention can be appreciated from the following Patent Claims.

The method is described in greater detail in conjunction with an illustrative embodiment of the invention and with reference to the accompanying drawings.

List of the drawings

Figure 1 is a schematic representation of the arrangement in accordance with the invention viewed from the front.

Figure 2 shows a side view of the arrangement in accordance with Figure 1.

Figure 3 shows a side view of the holder arrangement, the belt-like device and the workpiece during scraping.

Description of the method and the embodiment

Arranged on a frame A are feeder belts B and bearing brackets C for belt holders. A workpiece 1, for example in the form of a laminated parquet board, is advanced along a feed track 2 inwards towards the plane of the paper in Figure 1 (from right to left in Figure 2). In this way the workpiece is caused to pass beneath an application roller 3 for the application of stopper compound in a previously disclosed fashion. The application roller may be grooved in order to deposit a number of parallel stable strands of stopper compound on the workpiece. Once the whole workpiece has passed through the application roller, it is transferred sideways mechanically and automatically from feed track 2 to feed track 4. The workpiece is then moved along feed track 4 in a direction away from the plane of the paper in Figure 1 (from left to right in Figure 2). In so doing the workpiece is caused to pass a belt-like device 5 which is driven and controlled by two rollers 6 mounted to either side of the two feed tracks 2 and 4 in the bearings C. The belt-like device is driven in a direction cross-wise to the direction of advance of the workpiece. The belt-like device 5 largely forms an angle with the surface of the workpiece; see Figure 2. This angle is not shown in Figure 1. In order to obtain a good stopping effect, the angle of attack between the belt-like device and the workpiece is 2.5-60°, and preferably 5-30°. The belt material, belt thickness, belt speed, type of stopping material, and the rate of advance of the workpiece are so adapted that any excess of plastic stopping material accompanies the belt around the roller 6 situated closest to the stopping device and onwards as far as a scraper arrangement 7 which returns the excess material to storage

container 8 for the roller application device via a guide arrangement 9. In another embodiment of the invention any excess of plastic stopping material is instead transferred to and accompanies another belt-like device (not shown) which brings the excess stopping material to a scraper arrangement that returns the excess material to a storage container.

It is possible to appreciate from Figure 3 the appearance of the holding-down arrangement 10 which forces the belt¬ like device against the workpiece during scraping. The holding-down arrangement 10 consists of a belt holding device 11, a pressure cylinder 12 and the associated piston rod 13, which is attached to the belt holding-down device. The pressure cylinder 12 is accommodated in a box-shaped holder 14, from which two guides 15 extend for the sliding control of the holding device 11. The holder 14 is rigidly attached to a support beam 16. The support beam 16 is fixed between the bearing brackets C.

The workpieces generally consist of wood, primarily oak and/or beech. The wood is rough-ground prior to the stopping procedure, whereupon it is polished. The dust on the surface is blown, brushed and/or sucked away. The workpieces are advanced at a speed of 6-70 m/min, preferably 25-30 m/min.

The viscosity of the plastic material is preferably 300,000-900,000 cP. The plastic material is usually plastic-based and preferably UV-hardening. Hardening is performed most rapidly by subjecting the stopped workpieces to UV light from a radiation source in a separate later operation (not shown in the Figures) . The rate of hardening and the depth of hardening can be regulated for the same light source, for example, through the degree of pigmentation in the plastic material.

That part of the belt-like device which does not form an angle with the surface of the workpiece is in contact with the workpiece. This is made possible by the belt-like device being manufactured from a metal, such as steel, glass fibre material, ceramic material or the like, in a thickness of 0.25-4.5 mm, and preferably 0.8 mm, and being elastically resilient. The rate of advance of the belt, i.e. the rate of scraping of the material, is 3-90 m/min, and preferably 20-25 m/min.

Effective filling of cavities is achieved in that the wave of material in the form of stopping compound forced up by the belt 5, apart from being displaced in the longitudinal sense of the workpiece, also has imparted to it a lateral movement in the form of the stopping movement across the direction of advance of the workpiece. The arrangement in accordance with the invention accordingly permits excess plastic material to be scraped off in an elegant fashion in accordance with the invention from continuous and/or flat- surfaced workpieces, each of which workpieces is provided with at least one applied layer of the plastic material. The operation takes place automatically and as a continuous process which ensures that a workpiece which has once moved past the belt-like device 5 and, in so doing, has been divested of any surplus plastic material, need not move past the arrangement for a second time in order for the holes to be filled to their full depth or, alternatively, for any excess of plastic material to be further removed. Manual finishing of the stopping can be avoided, any excess plastic stopping compound can be returned to the process, and the complicated estimation of the vibration frequencies required for shaking the workpieces are avoided. Because the stopping is used efficiently and in the right quantity, relatively expensive stopping compound can also be used.

The invention is not restricted to the procedure described previously and to the embodiment illustrated here, but can be varied within the scope of the following Patent Claims. For example, the application roller 3 and the belt-like device 5 can be installed on the same feed track. It is also possible for two belt-like devices to be combined, in conjunction with which one is preferably set up for optimal filling at a certain angle to the workpiece, and the other for optimal scraping at another, larger angle to the workpiece. The belt-like device can also be so arranged that the direction of advance of the workpiece and the movement path of the belt-like device 5 form an angle other than the 90° shown in the example.