FI106743B - Method for drying wood material - Google Patents

Description

1 106743

Method for drying wood material

The present invention relates to a method for drying wood material in a production and manufacturing humidity, wherein the wood material is placed in an environmentally defined drying space where energy is supplied to dry the wood material, and wherein the wood drying is done in blanks or preforms vacuum is formed and the energy used for drying is introduced into the drying space as high frequency energy.

10 In the woodworking industry, it is generally a long-term process that wood material has been dehydrated and that production and manufacturing humidity have been appropriate. In many cases, drying of the timber has taken up to several weeks, so the drying process has led to attempts to handle even very large quantities of timber at a time. In this context it should be noted 15 that the quantities of timber required for production have in some cases been considerable. Handling large quantities of timber at one time leads to large stocks of timber which, in turn, are capital intensive, and in addition, not all affordable options, such as otherwise suitable but small batches of wood, can always be procured. A further disadvantage of the prior art is that in the course of drying also material which is not usable is dried. With large amounts of wood material to be dried, the amount of such non-recoverable material to be dried also becomes substantial.

·.! In order to eliminate the above drawbacks, solutions have been developed in the art which utilize a closed drying space, which is formed by vacuum and in which the energy used for drying is supplied as high frequency energy. Examples of such solutions include those disclosed in U.S. Patent Nos. 3,986,268 and 4,466,198 and WO 9601971. As an example of other solutions known in the art, the solutions described in U.S. Patent 4,246,704 and F1102694 may be mentioned.

However, the disadvantages of the solutions according to the above-mentioned publications are mainly that they are not so much intended for drying billets or preforms but mainly for drying large timber.

It is an object of the invention to provide a method by which the drawbacks of the prior art can be eliminated. 2 106743 have been achieved by the method according to the invention. The process according to the invention is characterized in that the blanks or preforms are bent during drying.

An advantage of the invention is above all that the drying process no-5 is substantially reduced compared to the prior art. For the sake of clarity, the invention refers to hours at the time of drying, whereas prior art refers to weeks. The fast drying process, in turn, allows for a low-capital, fast-moving raw material cycle. In addition to the fast 10, the raw material cycle enables you to obtain customer-oriented timber for the right purpose. Rapid drying of timber in pre-formulated blanks saves costs because only wood that is reused is dried. Another advantage is that the preforms can be made before drying. A further advantage of the invention is that the volume of the drying space is made substantially smaller than when using conventional technology, thereby reducing costs compared to the prior art.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be explained in more detail with reference to the accompanying drawings, in which Figure 1 is a side elevational view of the apparatus utilizing the method 20 of the invention and Figure 2 is a longitudinal view of the apparatus of Figure 1.

The figures show, in principle, an apparatus utilizing the method of the invention.

·. 25 Timber is made before the actual drying stage into preforms or preforms, which have sufficient labor to produce components that enter the product. The blanks or preforms are loaded into the drying load 2 of the drying space 1 either so that all the blanks or preforms in one load are the same, or in one drying load 30 2 all the blanks or preforms necessary for manufacturing the product are present. The blanks or preforms can be inserted into the drying space 1 through, for example, an openable filling opening 3.

The preforms or preforms may be sawn into shape, for example, curved chair legs or similar shapes. Blanks or components are made from fresh or pre-dried or dried wood below 106743 3 wood grain saturation point. The dryer load 2 is loaded into the drying space 1 with no gaps or only with small gaps compared to a conventional drying load.

In accordance with the essential idea of the invention, rapid drying is achieved using vacuum and high frequency energy. The use of vacuum or high frequency energy is, in principle, known in the prior art, but the invention utilizes the aforementioned matters in a new way. Vacuum is sucked into the drying space 1 by using a vacuum pump 4 and the energy required for drying is introduced into the preforms or preforms using high frequency energy, i.e. using the Greater 10 frequency generator 5 and electrodes 6, 7 located on opposite sides of the drying load. .

Because vacuum is formed in the drying space 1, the water to be removed from the wood material, i.e., preforms or preforms, boils at a temperature below the normal boiling point of water. By means of the high-frequency devices 5, 6, the energy required for the evaporation of water is introduced into the water-containing areas of the wood, whereupon the water is vaporized and ejected out of the blanks or preforms to be dried.

When properly carried out under suitable conditions, the process can achieve within minutes the moisture content of the preforms suitable for production or manufacture. In addition, the blanks or preforms are also bent during drying, for example, using a suitable mold or other aid.

Preferably, the walls of the drying space 1 are uninsulated, whereby the walls of the drying space can be used to condense moisture removed from the blanks or preforms. In this case, the heat released during condensation is retained in the process, improving the drying efficiency. It is particularly advantageous that the water condensed on the walls is directed to the lower part of the drying space 1, from which it is removed, for example, by means of a suitable drainage means 9. Water control can be enhanced by designing the drying space. It has been found particularly advantageous to form a drying space in the form of a tubular body of substantially circular cross-section, whereby water preferably drains to the lowest point of the pipe where it can be removed. Such a solution is shown in principle in the figures.

The embodiment illustrated in the figures is by no means intended to limit the invention, but the invention can be modified freely within the scope of the claims. Therefore, it is clear that the apparatus 4,106743 applying the invention or the details thereof need not necessarily be exactly as shown in the figures, but other solutions are possible. For example, the drying space need not necessarily have a circular cross-section as shown in the figures, but the drying space may be shaped differently, etc.

5

Claims (5)

A process for drying wood material to a production and manufacturing moisture content, wherein the wood material is placed in a drying space away from its surroundings, into which energy is conducted for drying the wood material and in which the drying process of the wood material is carried out in the form of semi-finished products. or semi-finished products (2) which exhibit a sufficient amount of workmanship for the manufacture of a part or component of the final product and that a negative pressure is formed in the drying space (1) and the energy used for the drying is led to the drying space (1) as high frequency energy. (5, 6, 7, 8), characterized in that the semi-finished products or semi-finished products (2) are bent in connection with the drying. Method according to claim 1, characterized in that the bending is performed by means of a mold or some other means. Process according to Claim 1, characterized in that the semi-finished products or semi-finished products (2) are made from fresh wood or wood which has been pre-dried or dried below the fiber saturation point. Process according to Claim 1, characterized in that the walls of the drying space (1) are used for condensing water removed from the semi-finished products or semi-finished products (2). 20 Process according to claim 4, characterized in that the condensate water is led to the lower part of the drying space (1), from where it is removed (9).