Съдържание


Vol. 8, Issue 1, 2019

KEYNOTE ADDRESS IX INTERNATIONAL SCIENTIFIC AND TECHNICAL CONFERENCE INNOVATIONS IN FOREST INDUSTRY AND ENGINEERING DESIGN – INNO 2018 STATE AND TRENDS IN THE DEVELOPMENT OF THE WORLD, EUROPEAN AND BULGARIAN FURNITURE INDUSTRIES

Автори: Vassil Jivkov

Резюме

The present article focuses on the important furniture production and consumption data in the world, Europe and Bulgaria, data about the main exporters in the world and regionally and furniture import. Main conclusions related to world production, consumption, export and import of furniture are drawn. Analysis of the Bulgarian furniture production and the market development have been made. Main trends in furniture market development in the following years globally are given. The information is based on data provided by CSIL (Centre for Industrial Studies, Italy), including official statistical data about the 100 most important countries in the world where the population amount to 6.6 billion, representing 85% of the total population on earth, Eurostat, Bulgarian Chamber of Woodworking and Furniture Industry and the National Statistical Institute.

Ключови думи: furniture world market, furniture world consumption, furniture world export, furniture world import, furniture industry

EN Version

IMPACT OF THE LOAD RATE ON THE ELASTIC PROPERTIES OF BEECH WOOD SAMPLES AT COMPRESSION TEST IN THE LONGITUDINAL AND TANGENTIAL DIRECTION

Автори: Kristijan Radmanović, Robert Roginić, Branimir Šafran, Matija Jug, Tomislav Sedlar, Ružica Beljo Lučić

Резюме

Knowledge of dynamic elastic properties of wood is an important precondition for rational and effective exploitation of wood raw material. In this paper, the impact of the load rate on the elastic properties of wood at the compression test in the longitudinal and tangential directions is analyzed. Elastic properties which were determined in this research are the modulus of elasticity, stress and strain at the point of proportionality and specific energy and power of elastic deformation. The research was carried out on beech samples that were prepared with smaller dimensions than prescribed in the norm (DIN EN 408) in order to achieve a more accurate determination of the specific energy and power of elastic deformation. The load rate was varied from 2 to 50 mm/min.

Ключови думи: wood, Stress, strain, elastic area, load rate

EN Version

ESSENTIAL OILS AS POTENTIAL ECOLOGICAL WOOD PRESERVATIVES – A PRELIMINARY TEST ON THYME ESSENTIAL OIL

Автори: Dana-Mihaela Pop, Anca Maria Varodi, Maria Cristina Timar

Резюме

The paper refers to a laboratory test, designed to allow a quick and reliable evaluation of the potential biocidal effect of essential oils. These are intended to be used as ecological wood preservatives with antifungal properties, for various applications including furniture conservation. The screening tests employed thyme (Thymus vulgaris) essential oil at 3 different concentrations and two types of fungi, one white rot Trametes versicolor and one brown rot Postia placenta. Based on these tests, thyme (Thymus vulgaris)essential oil has proven to be a potential active fungicide against the brown and white rot fungi, in a wide range of concentrations.

Ключови думи: wood preservatives, essential oils, screening test, thyme essential oil

EN Version

TOOLPATH GENERATION AND OPTIMIZATION OF MACHINING OF PINE WOOD SURFACES

Автори: Athanasios Makris, Ioannis Ntintakis

Резюме

In this paper are presented methods for wood working milling machining, specially we are going to use samples of pine wood. In the beginning a sculpture surfaces will be designed in a CAD/CAM software Fusion 360 and tool paths will be generated using four different strategies for finishing stage, these are: a) parallel, b) scallop, c) radial and d) pencil. On the upper machining surface of the final physical parts we measure the roughness in order to check the produced quality for each strategy. Each strategy compared according the total machining time, the cutting conditions and the geometric accuracy. Physical models will be produced with the use of a rapid prototyping machine ROLAND MDX- 40A for evaluation and tool path comparison.

Ключови думи: CNC, wood machining, tool path, CAD/CAM, milling, optimization, pine wood

EN Version

COMPUTATION OF THE CHANGE IN THERMAL CONDUCTIVITIES OF POPLAR LOGS DURING THEIR FREEZING

Автори: Nencho Deliiski, Natalia Tumbarkova

Резюме

A mathematical description of the thermal conductivities λ of frozen and non-frozen wood has been introduced in an own non-linear mathematical model of the logs’ freezing process. For the numerical solution of the model a software program has been prepared in the calculation environment of Visual Fortran Professional. With the help of the program, the 2D non-stationary distribution of the temperature and the change of λ in the longitudinal section of poplar logs with diameter of 240 mm and length of 480 mm during their 50 h freezing in a freezer at about –30 oC have been calculated. The change of λ in the radial and longitudinal directions of the wood on both surfaces and in the center of the subjected to freezing logs during the freezing process has been calculated, visualized and analyzed.

Ключови думи: poplar logs, freezing, radial thermal conductivity, longitudinal thermal conductivity, Visual Fortran

EN Version

FURNITURE AND INTERIOR ENVIRONMENT OF THE NATIONAL PALACE OF CULTURE: PUBLIC TRADITION ANDMESSAGE

Автори: Stela Tasheva, Pavlina Vodenova

Резюме

The paper investigates the interior and furniture of one of the biggest public buildings in Sofia, built in the period 1978–1981 – the National Palace of Culture (NPC). The study is focused on the evaluation of interior design, items and zones, in relation to the design solutions of key public interiors, which were widespread during the socialist period; and follows their presentation in professional publications of the period. The aim of the paper is to reveal the visual messages concentrated in the building and its interior spaces. Thus, researching the National Palace of Culture from the point of view of architecture and interior design specific features are revealed of the development of the contemporary history of design and the arts helps to define the understanding of artistic values, as well as the evolution and preservation of the cultural heritage of the 20th century.

Ключови думи: NPC, interior design, socialist architecture, traditions

EN Version

POWER ANALYSIS OF FORESTRY CUTTERS FOR COMMINUTING OF WOOD WASTE IN POPLAR CLEARINGS. PART 1: ENERGY INTENSITY

Автори: Konstantin Marinov

Резюме

Forestry milling cutters are increasingly used in modern forest technologies for soil preparation of reforestation. In forestry in Bulgaria, although more limited, there is a tendency for introduction of this kind of machinery. Milling machines have good technological qualities, but they also have some drawbacks, such as high-energy consumption and the need of more power drive. In the present work, an experimental study to determine the energy intensity of PT-400 forest milling unit with FAE-300S multifunctional forestry tiller for comminuting of left slash in poplar clearings, was carried out. Based on the results, regression models were developed to express the energy intensity of the forestry cutter, depending on the operating conditions and speed modes of the milling unit. In conclusion, under certain operating conditions, the optimal technological regimes for the operation of the forest mills are defined.

Ключови думи: soil preparation, poplar clearings, slash, fuel consumption

EN Version

POWER ANALYSIS OF FORESTRY CUTTERS FOR COMMINUTING OF WOOD WASTE IN POPLAR CLEARINGS. PART 2: POWER PARAMETERS

Автори: Konstantin Marinov

Резюме

Forest milling machines have high technological properties but also higher energy consumption and higher power requirements. In the present study, a theoretical analysis is performed to determine the power required for propulsion of specialized forest milling machines used for soil preparation of poplar clearings. For this purpose appropriate analytical dependencies are developed to define the required power of forest milling cutters for comminuting left slash and tree-shrub vegetation in fresh poplar cleaning, and shallow soil tilling. A new formula has been developed for a more complete definition of the power balance equation of forest milling aggregates for soil preparation. A suitable theoretical-experimental model for the determination of dynamic parameters in analytical dependencies is proposed.

Ключови думи: milling brush-cutter, poplar slash, power, resistance

EN Version

A STUDY OF THE RUN-OUT OF BAND SAW BLADES IN BAND SAW MACHINES

Автори: Vasil Vlasev, Petar Nikolov, Guerses Camber

Резюме

It has been studied the run-out in the cutting mechanism of band saw machines. The run-out of the band saw blade is viewed as the sum of the frontal run-out of the guide wheels and the band saw blade’s own run-out. Measurements have been made on the frontal run-out of the guide wheels and on three successive full rotations of the band saw blade. It has been found that there is no repeatability of the deviations in any subsequent or preceding rotation. The main result of the study is that the frontal run-out of the guide wheels is very small compared to the actual run-out of the band saw blade, but it is the factor influencing the shape of the deviations in its rotation. It is between 0.12–0.39 mm. The total run-out of the band saw blade, in 60% of all measurements, is in the range of 0.8–1.5 mm. Various band saw blade deviations have also been identified, according to which the cutting force variation can be determined for different parts of the blade.

Ключови думи: band saw machines, band saw blades, run-out of the band saw blade, frontal run-out

EN Version

OUTSOURCING IN DESIGN-PROCESS – PROBLEMS AND OPPORTUNITIES

Автори: Diana Ivanova, Pavlina Vodenova

Резюме

This report reveals the essence of outsourcing as a modern business model. Depending on the field in which it is applied, outsourcing can be considered as production outsourcing and outsourcing of business processes and services. The present study is focused on the outsourcing of business processes and services. The subject of the study is the outsourcing of the design process by business organizations, through which they improve their quality, transfer risk and save money. The purpose of the report is to identify the advantages and disadvantages, problems and opportunities of using outsourcing as a business model. We consider that the research on outsourcing of design process, based on the theoretical formulations and the best practices in this area, will be of interest for researchers and practitioners.

Ключови думи: outsourcing, design-process, furniture design, graphic design, problems, opportunities

EN Version

CONTRIBUTION TO THE METHOD FOR DETERMINATION OF DEGREE OF COMPACTION OF WOOD PARTICLES IN COMPOSITE BOARDS

Автори: Nikolay Yosifiov, Stefan Delin

Резюме

A mathematical model (algorithm) and a nomogram for determination of the compression ratio in flat-pressed composites on the basis of urea-formaldehyde resin as a binding agent and addition of paraffin have been presented in the investigation. By means of an algorithm (KD), the compression ratio of the wood mat during its piezothermal treatment is taken into account. As input data, following parameters are included in the algorithm for KD: bulk densities of the input wood raw material and the composite board; the specific weights of the paraffin and the binding agent; the moisture content of the composite board; the percentage of resin and paraffin; the volumetric swelling of wood.

Ключови думи: compression ratio, composite board, wood component, wood mat

EN Version

THE EFFECT OF SELECTED FACTORS ON THE MILLED SURFACE QUALITY OF NATIVE SYCAMORE MAPLE WOOD AND THERMALLY MODIFIED SYCAMORE MAPLE WOOD

Автори: Richard Kminiak

Резюме

The article deals with the issue of native sycamore maple wood and thermally modified sycamore maple wood milling on CNC machining centers. The milling of thermally modified wood is a very broad topic that deserves attention. The acquired knowledge concerning on the milling process may assist manufacturers improving the efficiency and quality of the process.

Article based on experiments in which was at 5 axis CNC machining center milled 30 mm thick sycamore maple board. In the milling process they were used finishing cutters LEUCO VFW 178354. The mean arithmetic deviation of the roughness profile was investigated during cylindrical milling of the board edges. This article focuses on finding the differences in the roughness of wood surfaces after surface milling of native sycamore maple wood and thermally modified sycamore maple wood and differing feed speeds (1-10 m.min-1).

In comparison with natural wood, thermal treatment had a negative effect on the quality of the wood surface after milling. The results also demonstrated an increased quality of surface finish with a decrease in feed speed.

Ключови думи: thermally modified sycamore maple wood, surface roughness, feed speed, nominal thickness of the chips

EN Version

ANALYSIS OF THE GEOMETRIC DESIGN OF THREE WIRE CHAIRS

Автори: Ioan Muscu, Biborka Bartha, Alin M. Olărescu

Резюме

Wire chairs, starting from the designs of Charles and Ray Eames (DKR Wire Shell, 1951) and Harry Bertoia (Diamond Chair 1952, Side Chair 1952), are a particular field of investigation for both the design historian and the designer. The geometry of their “shell” and supporting structure is still able to puzzle and charm. They are “sculptures made of air”, as Bertoia used to say, yet they are made of a simple industrial material. As true works of art, they fit in any kind of interior. They are often sought as precious vintage collectors’ items.

The authors seek to identify the general and particular features of these mid-century modern classics that had an iconic role in setting new forms and concepts, and to follow a part of their influence upon 21st century design. The analysis itself is allowed to develop into a design process, set between the spatial geometry of an artwork and the functional requirements of the chair.

Ключови думи: wire chair, geometric design, Charles and Ray Eames, Harry Bertoia

EN Version

DESIGN OF AN UXILIARY FURNITURE FOR PATIENTS IN REHABILITATION STAGE

Автори: Ioannis Ntintakis, Sotiria Ferfyri

Резюме

Human spin is a complicate and sensitive body part. Every spine is as unique as a fingerprint. Every person has his own unique ‘spine print’, and that print changes as the person’s posture changes. Injuries in the spine can cause serious problems in a person's daily life. Sometimes the conservative treatment that is often applied is not enough, so surgical intervention is necessary. A serious kind of spine surgery is spinal fusion which is a surgical procedure used to correct problems with small bones in the spine (vertebrae). It is essentially a "welding" process. After this stage, the patient is undergoing rehabilitation, a stage that varies from person to person. The rehabilitation stage is temporary and it is very critical for patient’s recovery. During this phase the patient have to follow doctor guidelines in a very restrict program. In current research, auxiliary furniture is designed, aimed to improving the quality of people life in rehabilitation stage after a serious surgery of spinal fusion.

Ключови думи: furniture design, universal design, patients, spinal fusion, rehabilitation stage

EN Version