Table of Contents

  • MACHINES

  • TECHNOLOGIES

    • ON THE APPLICATION OF FUNCTIONAL APPROACH TO CREATING AND PROVIDING OPERATIONAL CHARACTERISTICS OF ULTRALIGHT THERMAL PROTECTION OF REUSABLE LAUNCH SPACECRAFT

      pg(s) 109-116

      The main task of the research is to establish the regularities of the formation of a non-detachable compound of thin-walled elements from the Ni-20Cr-6Al-1Ti-1Y2O3 alloy and to determine the functional condition of the influence of soldering modes on the physical-mechanical characteristics of the compound. It has been shown the modeling of temperature fields in ANSYS 18.1. It has been established that the process of vacuum soldering should take place at a temperature of 1350°C for 15-20 min; the strength of the resulting compound is 390-420 MPa when the sample is stretched. The obtained information can be used as a theoretical basis for the development of the manufacturing process of the elements of the spaceship heat-shielding system.

    • OPTIONS OF REAL TIME MONITORING METALWORKING FLUIDS

      pg(s) 117-120

      The article is focused to describing the current monitoring systems for cutting liquids used in turning, drilling, milling and grinding operations. Based on the findings, a proprietary monitoring system is designed. The monitoring system consists of the hardware and software parts. The hardware part is a data acquisition device that contains sensors of concentration, conductivity, acidity and temperature. The device is located in the machine tank reservoir with cutting fluids. The Software section – The application displays current real-time information and a historical overview of the measured quantities. The application allows setting of limit values for monitored quantities and, if overtaken, it can alert the operator. The proposed device represents a simple way to control selected fluid properties during their life cycle.

    • ALGORITHMS FOR VECTORIZING DRAWINGS OF THE UPPERS SHOES

      pg(s) 121-123

      Perfection of methods of footwear production technology through the use of computer-aided design systems allows to develop production technology, to supply consumers with high-quality and comfortable footwear. At the stage of development of design and design documentation for a new model of footwear, there are a number of difficulties, the formalization of which using computer graphics tools would significantly reduce the subjectivity of the designer’s design decisions or free it from performing the same procedures. In the framework of the research known algorithms for vectorizing the drawing were considered, on the basis of which a new method using a set of apertures appropriate for the drawings of the upper parts of the shoe was proposed.

      The results of the research were – formulated requirements for the "Digitization" module; its structural and logical scheme, allowing automated input of information about drawings of designs of the uppers shoes in CAD; structural and logical scheme of a topological algorithm that allows vectorizing drawings of the uppers shoe in accordance with the set of apertures.

      The calculation of material costs for the design of footwear was also carried out, which showed the economic efficiency from the introduction of the proposed method into production.

    • ELECTRON BEAM ENERGY DEPOSITION AND RESIST PROFILE MODELING DURING ELECTRON BEAM LITHOGRAPHY PROCESS

      pg(s) 124-127

      Electron beam lithography (EBL) is a key technology for the fabrication of new generation integral circuits and devices of electronics, photonics and nano-engineering. The computer simulation of the processes of electron exposure and development of the resist profiles in EBL is important for the optimization of this expensive technology process, due to the expensive equipment used in microelectronic fabrication, the use of sophisticated materials and the long chain of sequential steps required to obtain the desired microand nano-structure. In this work investigation of the exposure and the development of Poly-methyl methacrylate resist (PMMA) with 100 nm thickness on Si substrate is presented. Different simulation techniques are implemented for the estimation of the distribution of the absorbed energy in the sample during electron beam exposure and for the development of the resist profile. Results from Monte Carlo simulation softwares CASINO, TREM, SELID are presented.

    • METHOD FOR PREPARATION AND SETTING OF A COLOR TONER-BASED PRINTER FOR COLOR MANAGED PRINT PRODUCTION COMPARABLE TO OFFSET TECHNOLOGY

      pg(s) 128-131

      The paper presents some of the results, obtained during the research on scientific project at TU-Sofia № 171ПР0012-06 “Research on the influence of using raster image processors (RIP) on the quality of color printing of poligraphic digital proofing systems“. The purpose of the parer is to present an optimized method for preparation of digital color toner based printer for color managed printing. The printer being researched uses specialized color server (RIP), that introduces many new functionalities, but at the same time introduces new difficulties related to setting the corrects settings in order to obtain predictable and repeatable quality prints. There are not many references in the literature to the correct way ot making these settings and the paper will be very usefull to those interested in the research of such printers as well as to practitioners in the field of digital printing, because it presents, in an organized way, the author’s experience in the research of these printers and his practical experience in the field.

  • MATERIALS

    • THE LABORATORY TESTING OF STEEL 20MnCr5

      pg(s) 132-135

      In this paper the laboratory tests on the selected steel for cementation 20MnCr5 was perfomed. The influence of the contact load resistance to the adhesion wear of high-temperature carbonitrided MnCr steels was analyzed. As a representative example was selected a tribosystem drive/driven gear of reducers in which are expressed high contact loads. For the purposes of these tests, the samples were first high-temperature carbonitrided, and then they are carried to the appropriate chemical and metallographic analysis, control of the surface hardnesses and the resistance to the adhesion wear. The aim of this paper was to observe the representative tribosystem as much possible to define its working parameters in order to determine the optimum conditions for testing the influence of the contact load on resistance to the adhesion wear. The analysis results show that high-temperature carbonitrided steel where the atmosphere of furnace at the beginning of carburizing was enriched with nitrogen, and finally with carbon showed significantly greater resistance to the adhesion wear compared to steel that at the beginning of carburizing had atmosphere of furnace rich in carbon, and finally with nitrogen.

    • ION PLAZMA NITRIDING OF MECHANICAL PARTS

      pg(s) 136-138

      This practical research work is devoted to the adaptation of technology for ion plasma nitriding of mechanical parts (pins and gears). Formerly these parts were inductive hardened, and requirement of the purchaser was to replace inductive hardening technology with the chemical-heat treatment i.e. ion plasma nit riding.

      Procedure for ion plasma nitriding of pin hammers and gears made of 4M2CrMo4 steel was described. Starting from the heat treatment of the parts, their cleaning and charging of the parts in the chamber. Description of the chamber and complete installation for nitride in is described. Experimental nitriding parameters are given too. Finally, accuracy of obtained results was checked using hardness measured of nitrided parts. Hardness values were in accordance with purchaser requirement.

    • COMBUSTION SYNTHESIS: FROM SIMPLE REACTANTS TO CARBON-RELATED NANOMATERIALS

      pg(s) 139-142

      Combustion synthesis (CS) is a technique for the synthesis of various nanopowders and complex compounds. This manuscript describes principles, some recent developments in CS and its exemplary applications: formation of silicon carbide nanofibers (SiCNFs) and transformation of synthetic and natural (Nepali dolomite) carbonates into graphene-related carbon nanostructures.

  • MACHINES

    • EMBEDDED RESEARCHES ON ADAPTIVE PARAMETRIC MODELING OF HYDRAULIC GEAR PUMPS

      pg(s) 90-93

      This paper presents some of the research results on a fundamental and applicative procedures regarding the integrated intelligent conception of a Romanian series of hydraulic gear pumps. Following the analysis of the pump series in the manufacturing process, the requirement for a modernized parametric design of this product has been identified. Thus, we observed the beneficiaries’ requirement for certain flows that are currently not provided by the current range of pumps. The parametric design of the pump leads to an easy and adaptive modification of the supplied flows, resulting in an innovative methodology which is very useful for the design and process engineers. The methodology is based on a computer-aided 3D modeling, specific pressure, drive torque, flow rate, etc. Each of these parameters leads to the intelligent modification of the certain geometric and functional features of the pump series designed to be adaptable to the dynamic demands of a modern economy.

    • POSITION CONTROL ALGORITHM FOR ANTAGONISTICALLY DRIVEN PNEUMATIC MUSCLE ACTUATORS

      pg(s) 94-97

      Pneumatic artificial muscles (PAM) have many useful properties (low cost, high power to weight ratio, flexibility…), but present a challenge if we want to achieve accurate position control due to their nonlinear characteristics. In this paper we present the development of the new control algorithm for the accurate position control of two antagonistically coupled PAM’s. We tested the algorithm on an experimental setup (rotational one-DOF pneumatic actuator with two PAM’s) for measuring muscles’ response. Newly developed control algorithm is an upgraded A-PID (Adaptive PID) control algorithm (by M. Pipan), that was developed for a linear actuator with only one pneumatic artificial muscle. The final part of this paper contains the comparison of experimental results to two other similar systems.

    • ANALYSIS OF A MECHANISM FOR SHEET CUTTING

      pg(s) 98-101

      Significant number of mechanisms for sheet cutting are already designed and produced. In spite of the fact that all of these mechanisms are suitable for cutting, all of them have some advantages and disadvantages. The aim of the paper is to present a new type of cutting mechanism. It is a crank mechanism with the cutting tool. The geometric and kinematic properties of the mechanism are analyzed. As the result the constraints of the mechanism are defined. The force and torque distribution of the elements of the mechanism is investigated. Based on the known cutting force the necessary input torque of the input element of the mechanism is calculated. In the paper a numerical example is considered. Based on the obtained results the discussion about properties of such mechanisms is given. Besides, the priority for application of such mechanism in comparison to the already known is motivated.