Съдържание


INNO 2/2015 2015

FOREST PRODUCTS RESEARCHES IN THE WORLD: FROM LJUBLJANA UP TO SALT LAKE CITY

Автори: Valentin Shalaev

Резюме

The International Union of Forest Research Organizations (IUFRO) is well known all over the world. It is the oldest and largest organization, which combines forces for about 15 thousand scientists from different countries and regions. The Fifth Division „Forest Products“ is rather significant among IUFRO nine Divisions. This paper examines the scientific directions of the researches, which are the closest to Fifth Division in IUFRO „Forest Product“. They are: the report „Future research in forest products“ by Walter Liese at the XVIII IUFRO World Congress in 1986 in Ljubljana and the report „Forest Products Research in IUFRO: History and Future in Meeting’s Needs“ by Robert Youngs and John Youngquist at the XXI IUFRO World Congress in 2000 in Malaysia. The wide range of active performing 32 working and special research groups reflects the totality of scientific researches made by leading scientists of the international scientist community working on the subject. The agenda of the XXIV IUFRO World Congress (Salt Lake City, USA) and Strategy on 2015-2019 „Intrerconnecting forests, science and people“ emphasizes the significance of this research trend in forest products and in the most general form it determines the dynamics of their development.

Ключови думи: IUFRO, Forest Researches, Forest Products, Directions

EN Version

EUROPEAN OAK’S GROWTH RINGS PROPERTIES: DENSITY DISTRIBUTION AND THERMAL BEHAVIOR ANALYSIS OF EARLY – AND LATEWOOD

Автори: Joël Hamada, Anélie Pétrissans, Frédéric Mothe, Philippe Gérardin

Резюме

Last decades wood is promoted as building material. Unprotected wood exposed to outdoor conditions undergoes a variety of degradation induced essentially by fungi attacks. Heat treatment of wood by mild pyrolysis (180°C<T<240°C under inert atmosphere) is a preservation process with a weak environmental impact, and therefore, is viewed as an interesting alternative to the chemical impregnation methods. Nowadays, the main difficulties of industrial processes are to obtain final products with a constant quality (durability, dimensional stability, mechanical properties and colour). These difficulties may be due to the heat transfer or the inter-specific or intra-specific wood heterogeneity. The aim of this study is to better understand the effect of the intrinsic wood properties: density according to the position in wood, and especially early wood versus latewood, on the thermo-degradation process. Heat treatment using thermo-gravimetric analysis (TGA) was performed on small samples of the European oak (Quercus petraea Liebl.), where the earlywood and the latewood constituting the annual rings were studied separately. The relationship between the radial variation of wood density components assessed by microdensitometer and their thermo-degradation sensibility was investigated. The results show that globally, earlywood and latewood behaved differently under thermal conditions, for the two studied trees; earlywood tended to be more sensitive to thermo-degradation than latewood.

Ключови думи: heat treatment, intra rings, micro-tomography, oak, TGA

EN Version

EVALUATION OF FOREST MILLING MACHINE PERFORMANCES FOR SITE PREPARATION

Автори: Konstantin Marinov, Velika Jordanova

Резюме

This article represents analysis of the technical capabilities of the specialized forest milling machine PT-400 with multi-purpose forestry tiller FAE-300/S for mulching, stump grinding and for deep soil preparation for establishment of intensive forest poplar cultures. The operating productivity, the optimal ways of movement, production capacity and some basic quality indicators of the machine have been determined under specific working conditions. The survey has been conducted on poplar sites and slashes along the Danube river valley.

Ключови думи: forest tiller, productivity, soil preparation

EN Version

IMPACT OF VENEER LAYOUTS ON PLYWOOD BENDING PROPERTIES

Автори: Violeta Jakimovska Popovska, Borche Iliev

Резюме

The research presented in this paper includes the study of the plywood bending properties through a change of the position of the layers in the structure of the panel around the central axis, without changing the number and the thickness of the veneers.
For studying this impact, experimental models of nine-layer plywood are made. The models are made from peeled beech veneers with thickness of 1,2; 1,5; 2,2 and 3,2 mm.
The modeling is made on the basis of changing the position of veneers with thickness of 3,2 mm around the central axis (axis of symmetry).
Pure water-soluble phenol-formaldehyde resin is used as plywood binder.
The bending strength and modulus of elasticity in bending of the plywood panels is test-ed in two directions, parallel and perpendicular to the face grain.
The research results showed that the tested plywood models meet the defined values of bending properties in accordance with the requirements of the MKS standard for structural plywood for use in construction. The different layouts of veneer sheets in panel structure gives opportunities for production of panels with different strength characteristics.

Ключови думи: plywood, veneers, bending properties, changes, position, layers

EN Version

PROGNOSIS OF MECHANICAL STABILITY OF STRUCTURAL PARTICLEBOARDS BASED ON MODIFIED PHENOL-FORMALDEHYDE RESINS DURING LONG-LASTING STAY IN THE OPEN IN REAL CLIMATIC CONDITIONS

Автори: Nikolay Yosifov, Stefan Delin

Резюме

Mechanical stability – relative reduction of modulus of elasticity and stiffness in bending, of structural particleboards (SPBs) based on modified phenol-formaldehyde resins (PFRs) during long-lasting stay in the open in natural climatic conditions has been determined experimentally. The impact of atmospheric effects by varying climatic factors, such as heating, wetting, freezing, insolation, etc., on strain-strength characteristic of SPBs has been established under field conditions.

To assess the mechanical stability of SPBs during long-lasting stay in the open in natural climatic conditions, respective algorithms and a diagram have been proposed. The traditionally used %, and for the stiffness – %, at a board thickness of 18 ± 2 mm, have been adopted as permissible rate of reduction of the relative modulus of elasticity. SPBs based on PFR modified with aluminium sulphate, in which % for a 10-year period of exposure in the open has been attained, have shown relatively highest weather resistance. For the boards based on PFR and aluminium sulphate, % for a 5-year period of stay in the open, but with respect to stiffness, the permissible duration of exposure is considerably lower – under 1.5 years.

Ключови думи: structural particleboards (SPBs); atmospheric effects; long-lasting stay; modified resin; stiffness in bending; module of elasticity in bending

EN Version

EQUIVALENT SOUND PRESSURE LEVELS IN WOODWORKING MILLING MACHINES

Автори: Pavlin Vitchev

Резюме

Equivalent continuous sound pressure level LAeq is the main variable characterizing the physiological effects of noise on humans. The technological equipment for woodworking and furniture industry includes the woodworking milling machines, which at the same time are characterized with high levels of noise emissions.

The current study investigates the changes in equivalent sound pressure level measured at workplace during milling of details from common beech wood (Fagus Sylvatika L). The influence of the construction and rotational speed of the cutting tool have been studied.

It was found that depending on the cutting speed and the construction characteristics of the cutting tool, the equivalent sound pressure level LAeq for eight hour working day varies from 74 dB(A) tо 89 dB(A).

Ключови думи: noise, sound emission, equivalent level, noise during milling

EN Version

CALCULATION OF THE ENERGY CONSUMPTION FOR DEFROSTING OF THE WOOD CHIPS

Автори: Nencho Deliiski, Veselin Brezin, Izabela Radkova, Anton Geffert, Jarmila Geffertova, Natalia Tumbarkova

Резюме

Аn approach for the calculation of the specific mass energy consumption  (in kWh.t-1) needed for defrosting of the wood chips, which contain both frozen bound an free water, has been suggested. For the calculation of the  a software program has been prepared in MS Excel 2010. With the help of the program calculations have been carried out for the determination of  for oak, acacia, beech, and poplar frozen chips with moisture content in the range from u = 0.4 kg·kg-1 to u = 1.0 kg·kg-1 and with an initial temperature at the range from t0 = –40 oC to t0 = –1 oC. At temperature equal to –1 oC the defrosting process of the wood chips has been fully completed.

Ключови думи: wood chips, defrosting, frozen bound water, frozen free water, specific mass energy consumption

EN Version

EMPLOYER-UNIVERSITY INTERACTIONS AS LEADING APPROACH IN TEACHING QUALITY IMPROVEMENT – RESULTS OF BG051PO001-3.1.07-0041 EDUCOMP PROJECT

Автори: Elizabeth Vatchkova, Radostina Popova, Nikolay Neykov

Резюме

The productive interaction between employers and university in almost each level in the University of Forestry is a part of basic approaches for gaining competitive advantages in the competitive struggle to attract students. Project BG051PO001-3.1.07-0041 EDUCOMP achieved spectacular results in that matter. In current paper an attempt is made for presenting the leading results of the project that influence the quality of interactions which could improve the quality of educational programs.

Ключови думи: employers, interaction, EDUCOMP

EN Version

STUDY OF VOC EMISSIONS AND ODOURS FROM FOAM MATERIALS IN FURNITURE PRODUCTION

Автори: Alena Capíková, Petr Čech, Daniela Tesařová

Резюме

The issue of volatile organic compounds (VOCs), odours or smells emitted from materials is researched in terms of our environment and human health. The Department of Furniture at Mendel University in Brno has been dealing with this subject for a long time. Main direction of this research is defined by composition of quantitative and qualitative emissions of VOCs which are emitted into the air from chosen materials used in the manufacturing of upholstered furniture such as polyurethane foams and latex rubber. Emission measurement is determined in space chamber with pre-defined conditions. This methodology is described in the standard ČSN EN ISO 16 000-9. The samples of air from the climate chamber, where the test sample is placed, are then analyzed by gas chromatography (GC) on a gas chromatograph with mass spectrometer and thermal desorption. Another part of this research is olfactometric assessment of odours emitted from tested materials, by the indirect olfactometry method. The relevance of the individual components on emissions of odour intensity and hedonic effect will be determined according to the chemical analyses of the achieved results.

This study investigates the problem of VOC emissions and odours emitted from polyurethane foam, viscoelastic foam and latex at the temperature of 23 °C and a relative humidity of 50 %. The time aspect in connection with the amount of volatile organic compounds released to the air are examined in this document. Particularly it was pointed on the identification of substances which release from these foams. These substances express the characteristics of the foam materials from the point of the release of volatile organic compounds and odours.

Ключови думи: VOC emissions, odours, gas chromatography, olfactometry, foam

EN Version

GUIDELINES FOR THE STUDY OF INNOVATION ACTIVITIES OF THE ENTERPRISES IN THE FOREST INDUSTRY

Автори: Radostina Popova

Резюме

This report presents the specifics of the study of innovation of the enterprises of forest industry. It includes recommendations for distinguishing innovation activities in product and process innovations, organizational and marketing innovations, and eco-innovations. The report presents typical examples of innovation activities in the furniture sector and activities that are not considered for innovative.

Ключови думи: innovation activities, technological innovation, non-technological innovation, forest industry, furniture enterprises.

EN Version

METHODS FOR ASSESSMENT OF SUPPLIERS OF RAW MATERIALS AND MATERIALS (UREA-FORMALDEHYDE RESIN)

Автори: Julia Mihajlova, Tsvetelin Evstatiev

Резюме

Raw materials and materials form a big part of the cost price of the end product. At the same time, the deviations from the requirements put forward to them impede the manufacturing processes, lead to additional expenditure for elimination and compensation of the discrepancies of the raw materials delivered, serious losses and lost profit for the manufacturer.

The provision of raw materials and materials of constant quality is not always achievable and that is why it is necessary to assess the deviations from the optimum requirements and to determine what it costs to us to eliminate / compensate them and at minimum expenditure at that.

In the report, methods for assessment of suppliers of urea-formaldehyde resin are presented. They reflect the relationship between manufacturing and financial indices (price, expenditure, lost profit) when assessing the losses from deviation in the raw materials quality.

Ключови думи: methods, assessment, quality, supplier

EN Version