Съдържание
- EXAMINATION OF THE DEGREE OF SHRINKAGE AND SWELLING OF THE DOUGLAS FIR CELL WALL
- INFORMATION MODELLING OF SUSTAINABLE BIOENERGY AND BIOFUEL PRODUCTION
- INFLUENCE OF SOME TECHNOLOGICAL FACTORS OVER VIBRATION SPEED WHEN MILLING WHITE PINE DETAILS ON A UNIVERSAL WOOD SHAPER
- MACHINES FOR PRIMARY LOG CUTTING: PART I – A STUDY ON SOME OPERATIONAL INDICATORS
- IMPACT OF FEED RATE ON ROUGHNESS OF THE CUT SURFACE AND ENERGY CONSUMPTION DURING CUTTING DRY BEECH WOOD WITH A CIRCULAR SAW
- EVALUATION OF THE MACHINED SURFACE QUALITY OF SCOTS PINE (PINUS SYLVESTRIS L.) WOOD SPECIMENS, DEPENDING ON THE CUTTING MODE OF A CNC MACHINE
- PROCESSING SAWLOGS INTO PARQUET BLANKS
- INFLUENCE OF THE COMPONENTS OF THE WINDOW ON THERMAL CONDUCTIVITY
- A REVIEW OF SOME FACTORS AFFECTING THE ACCURACY OF MEASURING THE GEOMETRIC CHARACTERISTICS OF MORTISE AND TENON JOINTS
- CHANGES IN THE SURFACE PROPERTIES OF WOOD DURING BROWN ROT
- PRODUCTION OF FURNITURE ELEMENTS WITH PARTICLEBOARD CUTTING WASTE CORE
- EFFECT OF AGING ON THE AESTHETIC AND DECORATIVE FEATURES OF THE INNOVATIVE SALIXDUO PRODUCT FINISHED WITH ACRYLIC AND POLYURETHANE LACQUERS
- FRAGMENTATION IN MACEDONIAN TRADITIONAL ARCHITECTURE IN RELATION TO THE WOOD AS A STRUCTURAL ELEMENT
- SPECIFICITIES OF BRAND DESIGN IN HIGHER EDUCATION
- ADVANCING FABRIC MATERIAL DIGITALIZATION THROUGH PHOTOMETRIC STEREO RECONSTRUCTION
Vol. XIII, Issue 2 2024
- EXAMINATION OF THE DEGREE OF SHRINKAGE AND SWELLING OF THE DOUGLAS FIR CELL WALL
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Резюме
Upon sorption of water, wood swells, and this swelling can be directly measured at the macroscopic level of the scale. The reverse process is called shrinkage. The two processes are reciprocal and can be studied at different levels of scale. More difficult to observe and measure is the sub-microscopic level, i.e. how the cell wall swells and shrinks. There is a difference in the structure of the radial and tangential cell walls due to the different dynamics of the cambium division.
The article studies the swelling and shrinkage of radial and tangential cell walls. An attempt has been made to model these processes geometrically at the cell level. Douglas fir early and late wood zones were studied.Ключови думи: wood, shrinkage, swelling, cell wall, Douglas fir
- INFORMATION MODELLING OF SUSTAINABLE BIOENERGY AND BIOFUEL PRODUCTION
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Резюме
The European Union's Circular Economy project aims to protect the environment and reduce dependence on raw materials. The present study examines the state and the perspective of the sustainable production and use of bioenergy and biofuels as key factors in the realization of a circular economy. For this purpose, an information model is presented. The methodology for building such a model includes a definition of target, scope and users; a generalized scheme of an information system for maintenance of criteria and certificates for sustainability of bioenergy and biofuel production; consideration of software platforms and resources for implementation and publication of the information model. On the base of the generalized schema, a prototype information system is developed consisting of a user interface, functional scripts and a database of bioenergy and biofuel production in Bulgaria. The analysis of data shows the necessity of developing unified standards and classifiers to resolve inconsistencies between bioenergy/biofuel production datasets in all European Union countries.
The report has been developed under the activities of project НИС-Б-1279/19.10.2023 at the University of Forestry, Bulgaria.Ключови думи: bioenergy and biofuel production, information modelling, information system, sustainable certificate
- INFLUENCE OF SOME TECHNOLOGICAL FACTORS OVER VIBRATION SPEED WHEN MILLING WHITE PINE DETAILS ON A UNIVERSAL WOOD SHAPER
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Резюме
This study presents how some technological factors influence the vibrations of the cutting mechanism in a woodworking shaper. The experiment was carried out at different operating rotation frequencies and with cutting tools of different diameters. During the experiment, scots pine (pinus sylvestris) test samples were milled. Measurements were made at four points in the radial direction. Two of them are located in the upper bearing housing, and the other two are in the lower bearing housing. A universal milling machine with a lower position of the working shaft is used for the experiment. During the research, attention was paid to some technological factors such as cutting speed, feed speed of the processed material, which is from 4m.min-1 to 16m.min-1, milling width 12 mm and thickness of removed layer 12 mm. The study is aimed at improving the reliability and efficiency of a wood shaper machine as well as ensuring the accuracy and quality of products.
Ключови думи: Wood shapers, cutting speed, vibration speed
- MACHINES FOR PRIMARY LOG CUTTING: PART I – A STUDY ON SOME OPERATIONAL INDICATORS
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Резюме
The paper presents experimental results obtained during the processing of logs with different machines for primary cutting of logs – a vertical band saw machine with a carriage feed mechanism (Üstünkarli – Turkey), a circular saw machine for logs (Kallion Konepaja Oy – Finland) and a mobile horizontal band saw machine (Arsov 90 Ltd. – Bulgaria). The places for conducting the research are the manufacturing conditions of Training and Experimental Forest Range "G. Avramov" – the village of Yundola, Training and Experimental Forest Range "Petrohan" – the village of Burzia and "Petnop" Ltd. – the town of Varshets. The influence of basic parameters related to processing with these machines – feed speed and cutting amount, on the quality of the obtained wood materials was determined. The evaluation metrics measured are dimensional accuracy and surface roughness. The productivity of the machines was also determined. The studied wood species was Scots pine (Pinus sylvestris L.). The results were analyzed, and practical recommendations were proposed.
Ключови думи: log cutting machines, Scots pine, productivity, roughness, work accuracy
- IMPACT OF FEED RATE ON ROUGHNESS OF THE CUT SURFACE AND ENERGY CONSUMPTION DURING CUTTING DRY BEECH WOOD WITH A CIRCULAR SAW
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Резюме
The feed rate during mechanical processing of wood is one of the factors that has a high influence on the roughness of the cut surface and energy consumption.
The roughness of the cut surface caused by traces of the cutting tool has an influence on the hydrothermal treatment and all other mechanical treatments of the wood. Greater roughness, due to faster evaporation of moisture from the wood, increases the percentage of drying errors. On the other hand, higher roughness values decrease the lumber yield.
Energy consumption is an indicator of the cutting resistance and it depends directly proportionally, or inversely proportionally when the thickness value of the sawdust is less than 0.1 mm. At the same time, the teeth do not cut the wood and they do not create sawdust but wood dust.
In this research, three different feed rates were applied (U1=12 m·min-1, U2=16 m min-1 and U3=20 m·min-1) for a constant cutting height of 45 mm in dry beech wood with moisture content W=10±1%. The measurements were made with a circular saw with diameter of cutting tool D=250 mm, number of teeth Z=40 and width of the cut b=3,2 mm. The number of rounds was n=5500 min-1.
Roughness measurements were taken with a digital comparator, according to the Rmax criterion.
Measurement data for energy consumption were taken with a clamp amperemeter.
The obtained results showed a pronounced significance, directly proportional dependence of the roughness of the cut surface and energy consumption on the feed rate.Ключови думи: beech wood, circular saw, roughness, energy consumption, the feed rate
- EVALUATION OF THE MACHINED SURFACE QUALITY OF SCOTS PINE (PINUS SYLVESTRIS L.) WOOD SPECIMENS, DEPENDING ON THE CUTTING MODE OF A CNC MACHINE
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Резюме
In this paper, the surface quality of scots pine (Pinus sylvestris L.) wood specimens, processed with a CNC woodworking drilling and milling machine with a negative face mill helix, has been investigated. The changes in the surface roughness, depending on the changes in main factors determining the cutting process, such as cutting tool rotation speed (n); feed speed (Vf) and radial depth of cut (h), have been evaluated. The quality of the processed surfaces was evaluated by the roughness parameter Rz, measured with a portable roughness tester, model Surftest SJ-210 (Mitutoyo, Japan).
Based on the experiments performed, graphical dependencies, presenting the influence of the individual factors on the quality of the processed surface, were derived. A regression model was derived that could be used for quantitative prediction of the surface roughness of Scots pine wood specimens when processed with a CNC machine, depending on the changes of the variable factors (n, Vf, h).Ключови думи: surface quality, CNC machines, cutting mode, milling, Scots pine, rotational speed, radial depth of cut, feed speed
- PROCESSING SAWLOGS INTO PARQUET BLANKS
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Резюме
The term parquet refers to a floor covering made of solid wood, consisting of interconnected slats in a horizontal plane. A parquet strip is the principal constructional element of the parquet. This wooden strip is obtained as a result of processing the flooring blank. In the sawmill processing of the sawlogs, the flooring blanks are sawn from the sawlogs, mostly in the radial and tangential direction. For such a purpose, sawlogs from domestic species and foreign species are used. Most dominant in this manner are the hardwood species, although softwood species can be used too. Among the domestic species, the most are beech, oak, acacia, elm, ash, and from the softwood species pine and larch.
The paper focuses on the maximum quantitative yield of beech and oak sawlogs intended for processing into parquet blanks. The sawing was conducted on a bandsaw. The blanks were with a thickness of 25,0 mm. The sawlogs belonged to the I, II, and III quality classes. A total of 12 sawlogs were processed, 6 from beech (Fagus sylvatica L.) and 6 from oak (Quercus robur). All sawlogs were with a constant length of 3,0 m. The mean diameter for beech and oak sawlogs was in the range of 34,0 to 36,0 cm.
The average value for the quantitative yield for beech sawlogs from I, II, and III quality classes was 37.90%. For the oak sawlogs from I, II, and III quality classes the average value of the quantitative yield was 39.40%.Ключови думи: beech, oak, sawlogs, maximum quantitative yield, quality class, parquet blanks
- INFLUENCE OF THE COMPONENTS OF THE WINDOW ON THERMAL CONDUCTIVITY
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Резюме
The purpose of the windows as a construction product is to provide the building with natural light and the opportunity to ventilate the interior and at the same time providing protection to the room against external influences such as wind and rain, as well as to prevent uncontrolled cooling or heating of the room or the whole building in which they are built in. A window is a complex product which is constructed of different parts that could be made of different materials. In addition to providing light and protection from external influences such as rain and wind, the window has a key part in the energy efficiency of buildings. Energy efficiency as a term is usually associated in with two separate approaches, energy effects of devices and energy efficiency measures. When it comes to an energy-efficient device, then it is the device that has a high degree of energy utilization, while measures related to energy efficiency are all that we can do to reduce energy consumption. In order to protect the energy of the buildings, among other things, well-chosen windows of good quality and their proper installation play a key role in it. This research is focused on how much the component parts of the window have an influence on the thermal conductivity of the entire window, in fact, how different combinations of profiles that are used and glass packages affect the coefficient of thermal conductivity of the windows.
Ключови думи: construction carpentry, window, thermal conductivity, energy efficiency
- A REVIEW OF SOME FACTORS AFFECTING THE ACCURACY OF MEASURING THE GEOMETRIC CHARACTERISTICS OF MORTISE AND TENON JOINTS
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Резюме
The geometric characteristics of mortise and tenon joints represent their ideal shape as well as the permitted deviations from that shape. Measurement accuracy as part of production metrology is of crucial importance for maintaining tolerances and fits as well as quality control in production. The closeness of the measurement results to the actual true value of the measurand depends on many factors. Some factors that affect the accuracy of a measurement are caused by the measuring equipment, the environment in which the measurement is performed, the operator who performs the measurement, the method and procedure of the measurement and the properties of the material.
This review paper presents an investigation of the factors and their affect on the accuracy of measurement of mortise and tenon joints while maintaining manufacturing tolerances. The purpose of this investigation is to consider the possibility of their minimization to obtain a more accurate measurement.
According to the theoretical analysis, the group of factors that express the heterogeneity and hygroscopicity of wood as a material have a great effect on the accuracy of the measurement.Ключови думи: measurement, accuracy, mortise and tenon joints, geometric characteristics
- CHANGES IN THE SURFACE PROPERTIES OF WOOD DURING BROWN ROT
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Резюме
We investigated the applicability of the instrumented microscratching and microindentation methods in the examination of fungal decay of wood. Samples of Norway spruce wood (Picea abies) were exposed to the brown rot fungus Gloeophyllum trabeum using the mini-block method. The decay progression was monitored at one-week intervals during the 8-week fungal exposure. The results were complemented by hyperspectral imaging. In contrast to the progression of fungal decay, measured by mass loss of wood samples and where decay could only be detected five weeks after exposure, signs of decay could be detected by microscratching and microindentation measurements after only two weeks of exposure.
Ключови думи: Norway spruce wood, fungal decay, hyperspectral imaging, microscratching, microindentation
- PRODUCTION OF FURNITURE ELEMENTS WITH PARTICLEBOARD CUTTING WASTE CORE
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Резюме
The scarcity of natural resources and the generation of waste without adequate disposal are worldwide concerns related to the linear production model. The present study is part of a research project to create a technology for the utilization of laminated particleboard cutting waste in furniture element production. A layer of waste details was laminated on both sides with High Pressure Laminate (HPL) with a thickness of 0.8 mm. Polyvinyl acetate adhesive was used for lamination. The influence of the lamination process conditions and the arrangement scheme of the core details on the appearance, bending strength, and processing features in the subsequent technological phases of the manufacturing process has been established.
Ключови думи: waste utilization, laminated particleboard, lamination, HPL
- EFFECT OF AGING ON THE AESTHETIC AND DECORATIVE FEATURES OF THE INNOVATIVE SALIXDUO PRODUCT FINISHED WITH ACRYLIC AND POLYURETHANE LACQUERS
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Резюме
An innovative research material called "Salixduo" was developed and patented as part of an ongoing shrub willow wood rods project. With a view to the final use of this product, it was decided to conduct aging tests of the finished product.
Two acrylic and one polyurethane lacquer were selected for testing. Their application by pneumatic spray in the form of two coatings was carried out in the technology laboratory of a leading manufacturer of lacquer products. After 28 days of seasoning under laboratory conditions (temperature 20±5°C and relative humidity 65±5%), the parts were cut into samples for aging tests. The coatings were then exposed to UV radiation, UV+IR radiation, and varying humidity and temperature acc. to the AMK procedure as a function of time. The parameters evaluated were appearance, color, and gloss.
Gloss testing of lacquer coatings was performed by a photoelectric method using a TESTAN DT-G268 gloss meter according to PN-EN ISO 2813:2001. Measurements were made at three angles of incidence of light at ten randomly selected locations in the direction along and across each sample.
The color determination was determined with a DT-145 colorimeter, using a CIELab measurement system equipped with a daylight illuminator and 45º/0° directional measurement geometry. Ten measurements were taken on each sample before and after application of varnish. They were carried out always in the same places, thanks to the marked measuring areas.
Based on the results of the tests, the most significant effect on changes in color and degree of gloss was found after exposure to UV, followed by UV+IR.Ключови думи: Salixduo, acrylic and polyurethane lacquer, aging, colour
- FRAGMENTATION IN MACEDONIAN TRADITIONAL ARCHITECTURE IN RELATION TO THE WOOD AS A STRUCTURAL ELEMENT
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Резюме
Intricate concepts of spatial organization characterize the traditional Macedonian architecture of the 19th century. The limitations imposed by specific materials and technological constraints during that era stimulated the development of intelligent and versatile spatial models. Among the defining features of that architecture is the intricate use of wood as a primary constructional element. This research seeks to investigate the qualities of fragmentation of the form and their practical application.
The study will commence by defining the concept of fragmentation as a fundamental aspect of architectural expression. It will then systematically analyze its physical and formal properties from various aspects such: materials, spatial structure, construction, grouping of window openings. It will also analyze aspects of human experience and perception, evident through: perception and experience, identity, functionality. The study will examine approximately 200 houses from this period.Ключови думи: fragmentation, rhythmic formations, spatial configuration, traditional architecture
- SPECIFICITIES OF BRAND DESIGN IN HIGHER EDUCATION
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Резюме
The report focuses on the problems and specificities of brand design of higher education institutions in Bulgaria, including an analysis of Medical University – Plovdiv and Technical University – Sofia, Plovdiv branch. The paper discusses the creation of a graphic identity, the development of a brandbook and its implementation. In addition, the benefits of brand design in higher education and its application in all aspects are presented. The report also includes a comparison with practices in world-renowned universities. The main objective is to explore how brand design can improve the communication, attractiveness and reputation of higher education institutions.
Ключови думи: brand, design, higher education, graphic identity, brandbook, Medical University – Plovdiv, Technical University – Sofia, Plovdiv branch
- ADVANCING FABRIC MATERIAL DIGITALIZATION THROUGH PHOTOMETRIC STEREO RECONSTRUCTION
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Резюме
Photometric stereo reconstruction is a contemporary approach to digitizing fabric surfaces. By capturing multiple images of the surface illuminated from various angles and analyzing the resulting shadows, this method reconstructs the material's volume. It excels in capturing intricate texture details, particularly on surfaces with microscopic intricacies like fabric materials.
Ключови думи: Photometric stereo reconstruction, textures, fabric surfaces, Adobe Substance Designer