Eng. Nicolae ENE

Contributions regarding the Optimization of Beech Conversion by using Operation Lines Equipped with a Single High-Capacity Band Saw

SCIENTIFIC COORDINATOR: Prof.dr.eng. Victor Dogaru

PhD thesis asserted at “Transilvania” University of Brasov – Faculty of Wood Industry, September 2005.

In the context of increasing competitiveness on the timber market which generates a non-concordance between sell prices and production expenses, this thesis aimed at a critical analysis of the more and more complex practical situations and pursued to establish the way to follow in order to achieve an optimum economic efficiency, in case of beech conversion by using modern band saws.

The development of a new technology is recommended, capable of increasing the conversion productivity and efficiency. The proposed technology uses a high-capacity band saw. A calculation relation is defined for its production capacity in case of processing beech logs with different sizes. This enhances optimization in terms of selecting the most suitable band saw that is going to be adopted for a certain technological line and also of synchronizing its conversion capacity with the production capacity of the circular saws on the same line, in order to eliminate narrow places.

The author proposes to divide the conversion process into two distinctive stages (separated by the steaming, preservation and kiln-drying sector):

• the first stage comprises ripping and crosscutting (rough conversion), on a single operation line;
• the second stage is meant to finalize processing, on a separate operation line, in order to obtain the sawn timber boards in accordance with the contractual requirements regarding dimensions and quality.

The efficiency of such a technology registers an accentuated increase, if the first line includes only a high-capacity band saw (48 – 50cbm logs / 8 hours). This assumes cutting the logs according to three different cutting patterns (for different log diameters) and applying the allowance for shrinkage, determined experimentally by the author as function of the position of each piece of timber relative to the annual rings direction.

Besides increasing productivity, an increase of the quantitative efficiency by 2% can be obtained, as well as an improved qualitative level of the cut parts. The latter is not only due to the increased dimensioning precision of the sawn timber boards, but also due to the methods proposed for identifying and eliminating all possible manufacturing flaws.