Table of Contents


    • Applications of collaborative industrial robots

      pg(s) 96-99

      Collaborative robots, or cobots, are increasingly being taken out from behind the cages and being used alongside human beings to automate a variety of tasks, including quality inspection, pick-and-place. Collaborative industrial robots are harmless to the human worker, affordable, and easy to use and program. This paper studies applications of collaborative industrial robots in industry.

    • Plastic gears: State-of-the-art design and technology (review)

      pg(s) 100-105

      A review of the retrospective and modern state in the field of theory and practice of plastic gears is presented. Various aspects of such gears design, technology and applications are discussed. It is noted that corresponding problems are under considerationpermanently on the last common engineering meetings and specialized ones. The analysis of the papers allows to conclude that main trends in plastic gears are the following once: comparison the experimental results with VDI 2736 and JIS 1759 normative paper data; development of the methods of accelerated tests; investigation on fatigue bending strength, pitting and wear resistance; improvement of the noise, vibration and harshness behaviors; analysis and optimization of reinforced composite materials structure; application of additive technologies; fabrication of high precise plastic gears and development of computer-aided design methodology.


    • Investigation of the influence of basic technical parameters of ribbon electron flow on the microrelief of the optical glass surface

      pg(s) 106-109

      The article presents the results of a study of the influence of the main technical parameters of a ribbon electron flow on the microrelief of the surface of optical glass. A mathematical apparatus has been developed that allows the processing of probe characteristics obtained by sensing the energy parameters of a paraxial electron flow. The dependence of the influence of the main technical parameters (shape, size and distribution of current density) of a low-energy electronic stream of ribbon form on the microrelief of the surface of an optical glass of the crown variety has been established. This made it possible to evaluate the interaction of the electron flow with the surface of the optical glass. It was also found that the useful current of the electron flow is about 30% of the total emission current of the cathode of the electron gun. It is shown that the following factors can influence the accuracy of determining the technical parameters of a ribbon electron flow by sounding: a decrease in the diameter of the probes under the influence of the electron flow and heating of the probes during measurement. The total error of the probe method for determining the current density of the electron flow does not exceed 8%. Using atomic force microscopy, it was established that after processing the surfaces of optical glass of the crown variety with a low-energy electron-beam of a ribbon-shaped shape, provided that the rational shape, size and distribution of current density both in the working space and on the treated surface are reduced by irregularities from 40-75 nm to 3.5-5 nm. However, it was noted that the surface of the glass after electron flow treatment has a more uniform structure and is free from microdefects, in contrast to surfaces without electron flow processing

    • Influence of chemical surface pretreatment on adhesion properties and protective effect of coatings

      pg(s) 110-114

      The quality of the resulting surface treatment is influenced especially by the pre-treatment of the substrate, the design of the surface treatment such as the choice of the coating system, the method and the quality of application. From a variety of chemical surface pre-treatment methods, Bonderite chemical pre-treatment is at the forefront. This chemical pre-treatment is used at ambient temperature, phosphate-free. It forms a nano-ceramic protective layer on steel, zinc and aluminum surfaces. The use of Bonderite gives the coating a high quality, which shows good adhesion and excellent corrosion protection. Contribution is devoted to the evaluation of these properties

    • High pressure die casting mould renovation by cladding

      pg(s) 114-116

      The paper presents the results of the research of the evaluation of the overlay layers quality made by the fusible arc methods. By applying arc welding methods, it is possible to significantly extend the life of injection molds and thus significantly reduce production costs. The newly formed layers must meet a number of requirements so as not to degrade the advantages of high-pressure injection technology over conventional casting technologies. High pressure casting solves most of the problems of conventional casting technologies such as: porosity of the casting, high surface roughness, long casting time, inability to produce thin cross-sections and low dimensional accuracy. During exploitation, the mold surface is damaged, mostly by thermal cracking and combined adhesive-abrasive wear. Material used for high pressure die casting permanent mold is a medium alloyed hot tool steel Uddeholm Dievar. Layers were made using three types of filler materials on the Fronius TransTig 4000. To eliminate the effect of mixing, three layers were made. The quality of the deposits was assessed by non-destructive and destructive tests.

    • Influence of complex ultrasound vibrations and composite lubricants on wear resistance of materials of endoprosthesis

      pg(s) 117-119

      As a rule, parts that are made of titanium alloys are critical parts that can work in corrosive medium, accept alternating loads, have certain parameters of surface quality and surface layer. A finite-element simulation of a burnishing process of titanium alloy Ti-6Al-4V (an alloy that is widely used in medicine, as an example in endoprostheses) with/without ultrasonic loading at various processing speeds was carried out. It is established that when burnishing with ultrasonic vibrations of the tool, it is possible to obtain a qualitatively different picture of the distribution of residual stresses in the surface layer of the part. The features of the contact interaction of the tool with the workpiece surface were established for ultrasonic vibrations of the tool. For finite element simulation two types of ultrasonic vibrations were chosen (according to real ultrasonic tool): longitudinal and longitudinal-torsion vibrations. It is shown that the use of ultrasound can reduce the temperature of the deformation zone, which is extremely important when processing titanium alloys. It was also found that the use of metal-containing lubricant can improve the surface quality  arameters after ultrasonic burnishing.


    • Porosity and corrosion properties of CoCr alloys for dental application

      pg(s) 120-123

      The paper deals with the problem of occurrence of internal defects in materials produced by SLM technology. The influence of the position of materials on the platform during the SLM on selected properties – porosity and corrosion resistance were examined. The reuse of non-compacted powder (three times recycled powder) and its effect on porosity and corrosion resistance of materials was also tested. Porosity was measured on metallographic sections in two perpendicular directions by image analysis, corrosion properties were tested by linear polarization method.

    • Investigation on the efficiency of internal crystallization chemical admixtures for cement concrete – structural characteristics

      pg(s) 124-128

      In recent years, the use of internal crystallization chemical admixtures for concrete and mortar to increase their water-tightness and other physical and mechanical characteristics has been of increasing importance in modern construction. These types of chemical modifiers allow for the effective replacement of conventionally performed waterproofing works (membranes, rolls, brushed or sprayed coatings, etc.) by purposefully improving the physical-mechanical characteristics of structural concretes, rendering them, to one degree or another, impermeable to water or/and aggressive agents from different origins. In the specialized world market for such products there are several leading competing companies – producers of internal-crystallization chemical admixtures, which have different activity in Bulgaria. Based on results of purposeful set of structural investigations (DTA, SEM, BET) conducted the purpose of the report is to assist participants  in the construction investment process in understanding the nature, specific characteristics and differences in the performance (effectiveness) of different products in terms of their ability to limit the ingress of water into concrete and reinforced concrete sections, as well as their ability to increase the durability of concrete as the main structural material.

    • Hydrophilized unsaturated polyester resin-based polymer-silicate compositions

      pg(s) 129-131

      This work is a continuation of the development of hydrophilized unsaturated polyester resin (HUPER). Again, the authors’ main aim is a possibility for hydrophilization of unsaturated polyester resin (UPER), but in this case the previously selected hydrophilizer cement ‘milk’ was replaced by the water glass component without disregarding the contribution of cement to the multicomponent hydrophilizing system. The special thing about this case is that there are a number of hydrophilizers, all of which individually have a hydrophilizing effect on resin, and that they are influenced by each other. This is of utmost importance not only for the hydrophilization technology but also for the research into important accompanying issues, such as kinetics, mechanical strength characteristics, spectrum and derivatographic analysis. This study only addresses some of the issues mentioned for reasons of volume of work. However, due to the possible interest they could arouse in the different fields of chemistry, in medical and technical terms, they are to be developed and resolved in the future.

    • Mineralogical characterization of different clay varieties on behalf of advanced industrial handling

      pg(s) 132-136

      Clay is a group of minerals that which is more industrial demanded material because of the specific strengths of some components of such clays in the fulfilments of some industrial and technological needs. The chemical composition and other important properties of clays are depended on the origin, location and some other environmental factors. The industrial applications might be varied upon the mineralogy of some of clay. In the existing research, three different types of clay were selected as the materials that namely as anthill clay, brick clay and roof tile clay. The selected types of clay samples were collected from three different regions in Sri Lanka. The collected clay samples were characterized using X-ray fluorescence (XRF) spectrophotometer, Fourier transform infrared (FT-IR) spectrophotometer and optical microscope. According to the investigation results, there were observed the presence of Fe as the most abundant element in all of clays at least 75%, large amounts of kaolinite in three clay types, intermediate amount of quartz and trace amounts of rutile in three clay types. In addition that it is possible to present muscovite in brick clays as a trace mineral and some trace amounts of Fe minerals such as glauconite and marcsite in three clay types. When comparing of the mineralogy of such clays mainly those clays are possible to be further developed as the adsorption materials (adsorber) for the recovering of metals from waste water and polluted air and a recovery material to remove some unnecessary components in chemical processes.