Лесотехнически Университет

Summary

In the current work are presented the results from an experimental procedure for the establishment of quantitative yields and their variation depending on the thickness and length of details, the defects of the wood and the location of the logs in the stems of Scots pine (Pinus sylvestris L.). The experimental procedure was performed according to standardized methodology with selected model stems. It has been established the presence, size and number of defects of treated wood by using EN 1927-2 standard. In the normal technological sequence the stems were cut of sections with lengths 1, 2 and 4 m, and from the obtained sections (logs for sawing) according to acute sawing method the boards were cut of details with a thickness of 3, 6 and 9 cm. The obtained results allow drawing analysis and conclusions in relation to quantitative yields and their change depending on the thickness and length of the details. On the basis of these results an analysis can be drawn in relation to the impact of disadvantages of the wood and the importance of the place for harvesting of the logs from the tree stems. The resulting information allows more accurate and objective assessment of the technology and the machines in terms of more efficient wood processing and manufacturing of materials from solid wood.

Summary

The results from the studies on the dimensional and qualitative characteristics of model trunks of Scots pine have been presented in this report. The following dimensional characteristics: diameter, length and taper have been determined. The presence, type and dimensions of knots on the outer surface of the tree trunks and inside the wood have been determined. The presence of decay, spiral grain and other defects of wood and trunk shape have been established. The results have been analysed and relations to the existing standards, possible application of wood and requirements to the solid wood materials have been made. Relevant methods and techniques for efficient processing have been suggested.

Summary

The expansions of the raw material base for solid wood materials production are particularly important in terms of wood deficit and increased consumption. The aim is to use solid wood materials production like replacement wood, which doesn’t deteriorate the performance of the finished products, as well as technical and economic production parameters. The Douglas fir (Pseudotsuga menziesii) is non popular wood species for Republic of Bulgaria. The studies for our country show that this tree species well adapted in these conditions, particularly in areas with high humidity. This gives reason to believe that this tree species is perspective for the production of solid wood materials.

This report presents the results of studies about the size and quality characteristics of Douglas fir stems.

Summary

This paper presents experimental work results on establishing the quantitative yield of sawing thin round Scots pine (Pinus sylvestris L.) logs for production of dimensional lumber without defects. The experimental work was performed on thin logs obtained from the top part of tree stems. These were examined for the presence of the wood defects, their size and number. Following the normal production sequence, the thin logs were sawn into lengths of 500, 800, 1000 and 1200 mm. These, in turn, were plain sawn into boards and after that into dimensional lumber with widths of 3, 6 and 9 mm. The obtained pieces were analysed and conclusions were drawn on the quantitative wood yield depending on pieces’ thickness and length. The data allow to evaluate more accurately and objectively the technology and machinery in order to ensure more efficient processing of thin roundwood.

Summary

This study examines some of the most common problems associated with cutting thin logs. Various authors summarise information regarding some of the characteristic features and difficulties that arise when cutting this type of timber. Several approaches are presented to processing thin logs with different types of primary woodworking machines. The dimensional and qualitative characteristics of this timber are directly related to the quantitative and assortment gains and the deficiencies and defects in the final product. The application of technologies for further processing the obtained bonded materials in producing engineered wood products (EWP) is associated with high labour costs and low quantitative and qualitative yields. Nevertheless, research in this area needs to continue due to the increasingly intensive decrease in the diameter of trees and, consequently, a decrease in the average and large construction wood.