FLOORBOARDS OR PARTICLE BOARDS

The invention subject matter is the process of production of a wooden core layer for floorboards or particle boards with face and back veneers or double faced layers.

In the 1940s, the Swedish company Kahr Gustaf developed the construction process of floorboards or particle boards with the core layer made of low quality wooden slats. The core layer was covered with a face layer of high mechanical and aesthetic parameters that fulfilled the functional requirements of the board. For example, this solution was presented in the Canadian CA430631 patent description. The core layer was made of numerous low quality wooden slats situated parallel to each other in the same plane. The construction development towards imparting favourable resilient properties resulted in the introduction of joints between the slats placed at the distances of the slits ranging from 0.5 to 5 mm. The German description of the DE102007062144 invention reveals a method of producing the core layer - its essence lies in the fact that nicks in the form of at least two grooves situated perpendicularly to the width of slats, placed nearby both of their ends, are made in these slats, which were previously manufactured and placed parallel to each other. Then, the slats are moved away by slits ranging from 0.5 to 5 mm in width, and the next phase includes inserting a fusible glue of a short hardening period and elasticity persisting after hardening into the grooves by a constant stream. The obtained binder obtained partially penetrates the slits between the slats, preparing slats' joints to the extent that is essential for the further phases of board production.

In hitherto prevailing production methods biological wood defects including knots, decay, and fissures lead to the fact that, during the first stage of cutting the planks into slats, a significant amount of waste is created even amounting to 40%. Such waste wood can be only used as firewood or recycled by an additional amount of work by joining short slat segments up to the required length by the well-known latching method.

According to the invention described in this document, the process of production of the wooden core layer consisting of numerous low quality wooden slats situated parallel to each other in the same plane within a slit distance ranging from 0.5 to 5 mm and joined together by at least two glue seams, can be performed by two technological methods.

The first method arising from this invention entails performing the following actions:

- lumber of 20-50 mm in width is cut into planks whose length depends on the core layer length and the technological extra length,

- next, some or several planks placed one onto another are used to prepare a packet of the length no shorter than the core layer width, attaching each following plank to the previous one with at least two linear glue seams at the same time, directed transversely to the plank length and simultaneously separating the planks by the slits' intervals,

- the next phase entails cutting the batch into slat grillages with a vertical log bandsaw, in the planes parallel to the side determining the batch height and positioned within the distance equal to the core layer thickness, - during the last phase a slat grillage is adjusted to the core layer size.

The slats of the core layer formed in this method are positioned along their length dimension.

It is advantageous if the plank glue seams of the packet are made close to both planks' ends and in places where knots and fissures are situated, which provides the continuity of the connection along the batch length after cutting the batch.

It is advantageous if glue seams are made using flat interleaved slats 0.5 to 5 mm thick and their width no shorter than the core layer thickness, and their length equal to the plank width.

It is also advantageous if the glue connections constitute glue seams 0.5 to 3 mm high.

The second method arising from this invention entails performing the following actions:

- lumber of 20-50 mm width is cut into planks, whose length is determined as a multiple of the core layer width and the technological extra length,

- next, some or several such planks placed one onto another are used to prepare a packet and simultaneously attaching each further plank to the previous one with at least two linear glue seams directed transversely to the plank length and separating planks by the slits' intervals,

- the next phase entails cutting the packet into some slat grillages with a vertical log bandsaw in the planes parallel to the side determining the batch height and positioned within the distance equal to the core layer thickness,

- arranging slat grillages next to each other into a slat plane as their number along its length dimension slightly exceeds the core layer length constitute at right angles to the slats, - connecting the slat plane along the direction of its length with an adhesive tape or pincers inserted into the cut grooves,

- a 180° turn of the slat plane and sticking a wooden back covering onto the whole surface,

- finally, cutting the slat plane along its length into strips of the core layer width.

The core layer formed in this method is composed of slats placed transversely to its length.

Making glue seams of the batch is equally effective in both aforementioned methods of core layer production.

The figures provide a technological description depicting successive steps of both types of the process of wooden core layer production. Figures 1-7 present the successive steps of the first process, and figures 8-11 show the final steps of the second process.

The first invented process of wooden core layer production is mostly applied to floorboard production where slats are directed along their longer sides.

Spruce lumber 40 mm thick and 120 mm wide is cut into planks (1) of length determined by the core layer (12a) length 11 = 1000 mm and the technological extra length x = 20 mm. Next, 8 planks (1), placed one onto another and joined with glue seams (3), are used to prepare a batch (2) of height h=360 mm that is larger than the core layer (12a) width bl = 340 mm. Glue seams (3) are made by a fusible glue of a short hardening period and elasticity persisting after hardening. Apart from joining planks (1) together, the glue seams (3) help to separate the planks (1) by slits (4) approx. 2 mm wide. This aim can be achieved by two types of glue seams (3) : in the case of narrower slits (4) by the direct application of glue binder (6) 2 mm wide after hardening, whereas in the case of wider 3-5 mm slits, interleaved wooden slats of a width larger than the g core layer thickness (12a) and length equals to the plank (1) width are used to paste them in these slits. Figure 2 depicts both versions of glue seams. Each subsequent plank is fixed to the previous one by at least two glue seams (3) directed transversely to the plank length (1) close to both ends of a plank, and in places where knots and fissures are situated. The force of press pressure is applied while sticking a batch (2). During the next phase, a vertical log bandsaw is used to cut a batch (2) with saws 1 mm thick into 12 slat grillages (7) of thickness g = 8 mm, in the planes parallel to the side that determines the height h of a batch (2) - they are at right angles to the planks (1) . During the last phase, each slat grillage (7) is trimmed to the sizes required by the core layer format (12a) bl = 350 mm and II = 100 mm.

The second type of the process of the core layer production is mostly applied in producing boards of bigger dimensions, linearly long strips, and especially large surface particle boards. A slat grillage (7) obtained by this technological method is manufactured by applying the process described as the first one provided that the planks (1) are cut in such a way that their length II is determined as a multiple of the n width dimension b2 of the core layer (12b) and the technological extra length x. A number of slat grillages (7) in accordance with the length 12 of the core layer (12b) is placed next to each other, forming the slat plane (8) - slats in the slat grillages (7) are directed perpendicularly to the length 12 of the core layer (12b) . Next, a longitudinal connection along adjacent slat grillages (7) is made with adhesive tape (9) and/or bands inserted into previously cut grooves. An adhesive tape (9) and/or bands (10) are placed inside the planned strips (11), only fairly in the zones along the longer sides when the whole width of the slat grillage (7) is used for the core layer (12b) as shown in Figure 8. During the next phase, after the slat plane (8) is turned 180 degrees, a wooden back covering (13), for example in the form of plywood 2-4 mm wide, is stuck to the whole surface. The final phases entail cutting the slat plane (8) into strips (11) equal to the core layer (12b) width b2 and formatting the length 12, or almost only dimensional formatting in the situation where the core layer (12b) occupies the entire width of slat grillages (7) .

While carrying out the test production of the core layers (12a) , planks of 1 m ^J were used to obtain 93 m ² of finished planks, and the waste material amounted to 10% instead of almost 40% if the individual technology is applied.

List of labels in the figure

1 - plank

2 - batch

3 - glue seam

4 - slit

5 - interleaved slat

6 - glue binder

7 - slat grillage

8 - slat plane

9 - adhesive tape

10 - pincer

11 - belt

12a - core layer conforming to the 1 ^st type of process

12b - core layer conforming to the 2 ^nd type of process

13 - wooden back covering

h - batch height

bl - width of core layer conforming to the 1 ^st type of process

b2 - width of core layer conforming to the 2 ^nd type of process

g - core layer thickness

11 - length of core layer conforming to the 1 ^st type of process

12 - length of core layer conforming to the 2 ^nd type of process

x - extra length