RADIALLY SAWN TIMBER - GLUING OF STAR-SAWN TRIANGULAR PROFILES INTO FORM-STABLE PRODUCTS WITH VERTICAL ANNUAL RINGS

A method is presented for the gluing of star-sawn triangular profiles of pine (Pinus silvestris L.) into form-stable wood products with vert ical annual rings. The triangular profiles are free from pith and from most of the juvenile wood. The method is based on dried and condition ed triangular profiles. Undesired defects are removed and the wood is finger-jointed into long lengths. In the finger-jointing, consideratio n is given to the appearance and annual ring orientation of the jointe d materials. After the jointing, the triangular profiles are planed an d glued into rectangular blocks with vertical annual rings. These bloc ks can then e.g. be used as construction beams or be sawn up into soli d wood panels. A pilot plant has been built for the manufacture of kno t-free solid wood panels based on the proposed method. Results show a total volume yield of 53.8%. Three critical production stages can be d istinguished: removal of knots and defects, planing, and division of b locks into boards. These three operations are together responsible for more than 93% of the total losses in the manufacture. The removal of knots and defects meant a volume loss of 12.8%. 13% of the manufacture d units were 2.1 m long without finger-jointing and free from knots an d other defects. The average length of the remaining pieces used for f inger-jointed units was 0.41 m.