Лесотехнически Университет

Summary

In this article the, process of longitudinal solid wood profile milling has been studied. In the first part of the article, an analysis is done with regard to: the profile of universal cutterhead used for experimental studies; the characteristics of the chips formation process by longitudinal milling; the influence of the feed per tooth and the accuracy of the cutter teeth placement on the quality of the processed surfaces. The conclusions will be used in the experimental investigation of the milling processes.

Summary

This article presents the results of experimental studies of longitudinal solid wood profile milling. In the present part II, the influence of the cutter rotational frequency and the feed rate on the roughness of the processed surfaces are tested. The studies were carried out in the laboratory of „Cutting of wood and cutting tools“ to University of Forestry. For this purpose universal wood shaper machine, model FD-3 (Bulgaria), with bottom-mounted shaft and mechanical feed of material was used. The results obtained can be used as a basis for the formation of specific recommendations aimed at increasing the reliability of the machine and the accuracy and quality of the production.

Summary

The paper presents basic energy characteristics of wood pellets from different producents. We took the samples from producents in Bulgaria and in Slovakia. Energy characteristics of the pellets, such as their dimensions, moisture content, content of ash, gross and net calorific value were estimated in accordance with European technical standards. We used the standard STN EN 14961-1:2010, Solid biofuels as a basic platform for estimation. Values of net calorific value belonged to interval between 16,103 MJ.kg-1 and 17,120 MJ.kg-1, moisture content values were in interval 7,2÷12 %. We observed ash content of the samples from 0,43 to 1,47 %. All of tested samples met the requirements of the standards for ecological biofuel.
 

Summary

Experimental researches were performed in winter conditions with a horizontal band saw „Wood-Mizer“ WM 3000. The tests were conducted in manufacturing conditions of the „Chil Tepe – 97“ Ltd. facility in town of Laki by processing spruce logs. Two types of cutting tools were used: with normal and hardened teeth. The results are analyzed and some recommendations are proposed for more efficient use of this machine types.

Summary

The paper presents some experimental results concerning cutting process of poplar and pine logs through wide band saw blades with part-set and swage-set teeth. The researches were carried out in a production process of company „Fagus Ltd“, town Pernik. The influence of the feed speed and height of cutting on the productivity of the process and energy consumption were analyzed. The results are suitable to have a better knowledge and work out of the production and operating indexes and its optimization by using of wide band saw blades.

Summary

This report presents some problems on the state and future use of biomass as a renewable source for production of heat and electricity in Bulgaria and Europe. The report covers the potential opportunities of the agricultural lands in Bulgaria for production of energy plantations (SRP) and in particular from forest tree species such as poplar, willow and black locust. A review of their main advantages and disadvantages is made and recommendations for their future development in Bulgaria are presented.

Summary

A study on the technologies for creating and growing SRC plantations for the production of biomass for energy purposes has been conducted in the present report. An analysis of the main steps in the technological process has been made. Recommendations are made to the Bulgarian farmers on the necessary techniques for incorporating the crops and the use of appropriate machinery for site preparation, planting and growing of crops.

Summary

The present survey analyzes the key technologies for harvesting SRC plantation for production of biomass and the typical harvesters, suitable for willow, poplar and black locust harvesting in Bulgaria. The advantages and disadvantages of the various technological schemes are highlighted and some recommendations to the Bulgarian producers on their application are made.

Summary

Sharpening and smoothing of cutting tools are basic and final stages in their preparation as well. Moreover, in these processes can not always get a edge with the necessary quality. This requires engineering and technical staff directly involved in the maintenance of the instruments to have good depth knowledge and practical skills.

The article presents results of experimental studies of narrow band saw blades sharpening with abrasive tools with ceramic and organic bond. The indicators of performance and quality of abrasive tools are defined. The durability of sharpened band saw blades was determined.

Summary

The process of woodworking tools sharpening is a direct connection from the right choice of the abrasive tools form and its characteristics. Commonplace in companies of the woodworking and furniture industry are significant difficulties on the correct selection and use of abrasive tools. This is negatively affects on productivity and sharpening of cutting tools, respectively, on the cost of tools and materials.

The article presents some experimental results concerning indicators of performance and quality of abrasive instruments with ceramic and organic bond by sharpening of circular saws with steel teeth and made appropriate recommendations for their use.

Summary

The article presents the methodology and results of an experimental testing of the calorific value and ash content of wood chips, used as a fuel for heating and electricity plants. The wood chips was extracted from willows’ short rotation plantation of Salix Viminalis – klon Tordis. Studies were conducted in the “Department of Forest Harvesting, Logistic and Amelioration” of the Technical University in Zvolen, R of Slovakia. Wood chips produced from Salix Viminalis, klon Tordis indicates a high gross (20,597 MJ.kg-1) and net calorific value of dry mass (19,255 MJ.kg-1) under the specific production conditions. Naturally dried wood has a relative humidity Wr = 11,3 % and according to ISO 1928:2011 it has a clean net calorific value 16,907 MJ.kg-1. This gives grounds to assume that the wood produced from such an energy plantation will have high energy characteristics and will satisfy the market for energy chips.