Contents


Vol. IX, Issue 2 2020

INNOVATION OF CNC MACHINERY PROGRAMMING EDUCATION AT THE FACULTY OF TECHNOLOGY

Authors: Peter Koleda, Pavol Koleda, Štefan Barcík

Summary

The paper describes the educational project ending in 2020, which is focused on increasing the quality of teaching and making the study more attractive by introducing new selective courses: CNC technology in bachelor study programs and Programming of CNC technology in engineering study programs at the Faculty of Technology of the Technical University in Zvolen, Slovakia. The solution of the project is also to create a background for building a CNC machining workplace. The article summarizes the educational machinery for teaching especially milling operations. Teaching programming takes place in professional CNC emulators that are commonly used in praxis. These emulators allow program debugging, tests, trajectory drawing and optimising and collision checking of tool and workpiece. Altogether 23 students successfully completed the introduced course. Within the project solution, 5 theses were defended.

Keywords: CNC programming, CNC simulators, teaching, innovation, workplace building

EN Version

ANALYSIS OF FACTORS EFFECTING ON QUALITATIVE PARAMETERS OF SURFACE WHEN PLANAR MILLING HEAT–TREATED OAK WOOD

Authors: Marek Vančo, Michal Korčok, Štefan Barcík, Zhivko Gochev

Summary

This article deals with the experimental examination of the temperature influence of heat–treated oak wood in terms of quality of the machined surface, as well as analysis of the impact of monitored independent parameters: cutting speed, feed rate, material, angular geometry of the tool, on dependent parameters representing surface treatment quality (Ra – mean arithmetic roughness) in flat milling of thermally modified oak wood (T = 160°C, 180°C, 200°C, 220°C), and their comparison with native wood. The roughness measurement was carried out by non–contact method.

Based on experimental measurements, the effect of the observed factors on surface quality was determined in this order: used type of cutting tool, thermal modification, cutting speed, feed rate, rake angle.

Keywords: surface roughness, plane milling, ThermoWood®, quality of machining

EN Version

SURFACE SMOOTHING OF THE SIDES OF PRISM-SHAPED BEECH WOOD DETAILS VIA LAPPING WITH FAST-ROTATING METAL CYLINDER

Authors: Dimitar Angelski, Andrey Kavalov, Vladimir Mihailov

Summary

The article presents and analysis the results from laboratory experimental researches over opportunity for effective surface smoothing of cutter-processed or initially sanded surfaces of prism-shaped steamed beech samples with grit number of a sandpaper № 80. The lapping is executed by a special work instrument – cylindrical steel circlet, loaded on the milling spindle. Upon handing over and further pressure of a detail to the smooth polished surrounding surface of the rotating bushing, the lapping that occurs results in smoothing of the detail’s surface that has been in contact. It is also due to the partial heating, densification, decrease and rounding of the tops of the microgrades remaining after sanding. The purpose of the research has been to evaluate the degree of smoothing, by checking the multiple influence of the major factors on which it depends. In this particular case, we have chosen to vary the following factors: feed speed of detail U; radially directed force of pressing to the spindle q; number of impacts over the same surface n. The research results show that a quality smoothing, equal to the traditional one that is double sanded with sandpaper №180 or №240, can be reached at values of the variable factors, as follows: u = 8÷10 m.min-1; q = 6÷8 kN.m-1; n = 1÷2 impact. Apart from the quality smoothing, this lapping method results in further economy of sandpaper and lacquer of up to 20%.

Keywords: surface smoothing, lapping, beech, lapping regime

EN Version

UNIVERSAL DESIGN – SOCIAL, PEDAGOGICAL AND MANAGERIAL CHALLENGE

Authors: Ophelia Kaneva

Summary

Universal design (UD) as a concept of consideration rather than an afterthought that may lead to subsequent adaptations – following the principle of early intervention to address the cause, rather than the symptom. It enforces and empowers everyone to play a full role in society. Individually and mutually, professionally and secularly, UD should fly inspirationally above all social areas. A physical platform which allows to be complemented by practical and emotional learning, that fights stereotypes and prejudices and examines the limits of normality by defining difference as the new normal – is excellent example for Universal design. So, Universal design is the natural way things happen for everyone. Therefore, it should preferably be possible to influence, to attract and invite ideas leading to something everyone can agree with and something that comforts all in own understanding of successful living and prosperity.

Keywords: universal design, managerial challenges, social welfare through design, pedagogical challenges, UD

EN Version

25 YEARS OF THE ENGINEERING DESIGN PROGRAM: CHALLENGES AND SUCCESSES

Authors: Regina Raycheva

Summary

The paper is an attempt to summarize 25 years of experience of Furniture Design Education at the University of Forestry. The author attempts to look at the whole complex circle of problems facing the management and teaching staff at the university, such as compiling of curriculum and syllabi, creating study content and textbooks, securing study space and all organizational issues. On the non–material side key issues were: awareness of the creative nature of the designer’s profession; establishing of artistic ethos and new relationship between staff and students; innovative teaching methods encouraging self-confidence and presentational skills of young people. These issues include not only staff and facilities, but also active involvement of students. Here we mean active student participation in: mobility programs abroad, national and international workshops, annual exhibitions, introducing opportunities for professional career at the university. In this line we can add the educational module “Project Week” and links with business. Meanwhile, positive program accreditation of the Engineering Design Program by the National Accreditation Agency; as well as the image of our alumni and their overall professional career gave the first rewarding signs. Last but not least, the report compares the program with analogical programs elsewhere in Europe with consequent conclusions for success and failures.

Keywords: design, creativity, engineering design, education

EN Version

MINIMALIST HOUSING UNITS. ECO AND SMART TRENDS

Authors: Ralitsa Stavreva-Pancheva

Summary

Minimalist housing units are a contemporary tendency that has developed widely in recent years, motivated by changing lifestyles and demographics, global social, economic and environmental problems. This requires reconsideration of needs and requirements of society in connection to the living environment and its sustainable development. The aim of the scientific research is to evaluate the contemporary architectural forms of the small urban dwelling and its interior environment peculiarities. This research presents an analysis of innovative examples in the context of the minimalist housing unit and its affordability. The focus is on the development of the small urban dwelling both for the benefit of the contemporary consumer and as a tool for dealing with many global problems and environmental changes.

Keywords: minimalist housing unit, eco, smart solutions, affordability, sustainability

EN Version

FORMAL-ANALYTICAL DESCRIPTION OF WOOD FOR THE PURPOSES OF THE CLASSIFICATION OF WOOD SPECIES. PART 1: QUANTITATIVE LEVELS

Authors: Nikolai Bardarov, Vladislav Todorov, Petar Antov, Mariana Kaludova

Summary

Wood is a product of woody plants, formed by a complex of tissues - conductive, mechanical, reserve and secretory. However, it is not just a mechanical mixture of chemical compounds, but a complex biological and physico-chemical system composed of polymers, monomers, made up of cell walls and cell cavities (lumens). The knowledge of its structure allows the tree species to be determined, the conditions under which it is formed, as well as its behavior under different loads.

The paper examines the variation of the quantitative indicators of individual tissues and the possibility of using it to classify individual species.

Keywords: structure, levels, vessels, wood rays, fibers, parenchyma

EN Version

THE FORMAL-ANALYTICAL DESCRIPTION OF WOOD FOR THE PURPOSES OF THE CLASSIFICATION OF WOOD SPECIES. PART 2. WOOD FORMULAS

Authors: Nikolai Bardarov, Vladislav Todorov, Petar Antov, Mariana Kaludova

Summary

The structure of wood can be examined at several qualitatively different levels of consideration (macro, meso, micro and nano). Each of these levels can be considered as a separate, single and relatively independent subsystem in the wood structure. They are determined by the characteristics of the species, the ecology of the global, regional and local habitats. Each of these levels requires a separate, more precise and comprehensive classification. If the quantities and distribution of the main tissues are known, the tree species can be grouped in groups of construction and conclusions can be made about its physical and mechanical properties.

This work examines the possibility for a more in-depth formal-analytical description of the individual tree species and a theoretical representation of wood structure that more adequately reflects its characteristic features.

Keywords: wood, structure, levels, vessels, core rays, fibers, parenchyma, wood formulas

EN Version