DK173609B1 - Method for reducing risk of splitting in round timber through removal of the central portion prior to drying - Google Patents

Description

in DK 173609 B1

Description

This invention aims to minimize the staining problems that arise when drying around uncut wood. The technique will have great scope for the utilization of small-sized round wood, which through this technique will have a real significance as nothing but firewood.

Wood fades on drying. The size of the shroud is uniform in the longitudinal direction, radially and tangentially. Technically, especially, the difference between the radial and tangential shrinkage causes problems, in that it causes casts, dimensional changes and staining as the wood is dried. Typically, the tangential shrinkage is twice as large as the radius, causing uncut wood to crack during drying. See Attachment 15 and Figure 1 and Table 1 of Thomas Thomassen's 1977 book "Wood and Wood Materials".

In practice, these problems have so far been solved by cutting the wood into planks, etc. prior to drying. The stresses in the wood, which arises during drying, can thereby be relieved without the wood splitting. The dimension changes can possibly be corrected subsequently by planing etc.

For effects produced without cutting, spotting along the length of the tree has so far been accepted, as this in itself does not substantially reduce the strength of the tree. For carpentry purposes, where appearance is the most important, the utilization of roundwood in its entirety has traditionally caused so many problems with splicing that roundwood is not really used for carpentry work.

30 It is known to provide veneers and planks with holes prior to drying for the purpose of preventing cracking - cf. patents GB 2,058,315 A and SE 504 621 C2. These, however, both start from cut wood and process this from the side, where my invention is based on uncut 35 roundwood, from which the core is emptied from the inside and in the longitudinal direction of the tree.

Externally, apart from the end surfaces, there will thus be nothing to observe on the tree after treatment by my method, contrary to the prior art. A crucial difference if the roundwood in its entirety is to be utilized for carpentry and crafts.

40

The principle of my invention is to remove a large part of the core of the piece of wood prior to drying. This gives the advantage that the piece of wood can actually disappear more radially, since there is not a core that provides a backpressure. The difference between the radial and the tan- gential shrinkage is thereby in fact reduced, thereby minimizing the risk of staining.

DK 173609 B1 2 In a piece of circular wood where a hole with a diameter of x% of the diameter of the piece of wood is drilled prior to the drying, the drying stain will in principle only be x% in relation to a corresponding untreated piece of wood (Figure 2, Figure 3 and Figure 4). In practice, the effect is even 5 much greater, since at the same time the piece of wood will be able to compress the innermost cells somewhat, thus removing an even larger part of the tension between the cells at the outermost part of the tree.

With the right combination of drying technique and pre-drilled hole, the threshold for when the wood is stained can be raised so much that staining is avoided.

According to the above, the greatest success is achieved with the largest hole possible. However, the size of the hole is limited by the practical application of the wood afterwards.

15

Technically, the center of the tree can be removed in many ways (drilling, milling, etc.). Importantly, however, the wood does not dry out beforehand, and drying should be relatively gentle, as the risk of staining remains, albeit substantially reduced.

When the pieces of wood are dried, they can be processed with old-fashioned techniques for all kinds of carpentry, where the beautiful appearance and play of the round wood can come into its own. Only restriction is that the 25 missing centers must either be included in the finished product or be replaced by other material. As Figure 5 is attached image of four-candle candle holder that I have made in this way. Notice how bark, splinters and pine trees can suddenly form part of the finished product that is not stained.

30

Especially for small-dimensioned wood, this method of reducing dry spotting will have the greatest prospects, as this tree is not appreciated today in the industry. The prospects are thus not only sufficient to create “industrial crafts” on the basis of 35 round wood. The perspectives also extend to forestry, fruit growers, etc. who, if these things are taken up industrially, get a marketing niche for their small-sized tree.

Claims (1)

DK 173609 B1 Method for reducing the risk of speckling in round wood, characterized in that the central part of the round wood is removed prior to drying the tree.