Machines. Technologies. Materials.
Vol. 15 (2021), Issue 6

Table of Contents

  • MATERIALS

    • Coupled two-carrier planetary gearboxes for two-speed drives

      pg(s) 212-218

      The following paper reviews all the possible cases of coupled two-carrier planetary gears with four external shafts. An emphasis is made on the work of these gears with one degree of freedom, one input and one output shaft and brakes on the other two shafts . When switching over the gears, the speed ratio of the gear is changed, thus allowing the use in two-speed mechanical transmissions of technological lifting and other machines. Some relations are deduced for determining the speed ratios and the efficiency of all structural schemes.
      Recommendations for the selection of the most appropriate structural scheme according to the current necessities can be made. A 3D model of the S13V3 two-speed, two-carrier gearbox was created to demonstrate the process of determining the viability of a particular gearbox layout.

    • Impact of the Number of Passengers in the Vehicle Braking Performances Equipped with Modern Mechatronics Braking System

      pg(s) 219-222

      Modern vehicle braking systems mainly are based on deceleration of vehicle and tire slip control. Trends in improving vehicle braking performance give rise to a large variety of braking systems and control strategies. An anti -lock braking system is an electronic braking process control system, which greatly increases the ability of the driver and vehicle to avoid road accidents even during difficult braking conditions or circumstances. The load (number of passengers in the vehicle) which is transmitted to the road surface through the vehicle tires is an issue which directly affects the braking efficiency of the vehicle during stopping. The braking efficiency also depends on
      the material of the road surface, climatic condition, road condition, vehicle speeds and tire condition.
      The purpose of this paper is investigation the impact of the number of passengers in the vehicle during the braking process, respectively to determine the performance of the braking of vehicles equipped with modern mechatronic braking systems such as: Antilock Braking System, Electronic Braking System, Emergency Brake System and Electronic Brake-force Distribution System.
      The braking performance of the vehicle was determined experimentally through the XL Meter device which was fixed on the windshield of the VW Polo vehicle. The tests were performed on asphalt roads for different speeds of 40, 60 and 80 km/h. The determination of the center of gravity of the vehicle and the reaction forces in the front and rear axles was performed through the devices in the Motor Vehicle Laboratory of the Faculty of Mechanical Engineering and the developed mathematical model for calculating static and dynamic reactions forces for the respective axes. The obtained results will help the traffic experts in the analysis of road accidents.

    • A new commercial dishwasher design using mineral additives in its drying system

      pg(s) 223-225

      Commercial dishwashers in different performance classes are used in all industrial kitchens. In contrast to existing commercial dishwashers, there is an increasing demand for products that use drying technology to meet customer wishes and needs. Various household dishwashers having zeolite mineral during drying prevents water droplets and detergent stains (including surfaces of plastic containers) on the surfaces of dishes and rinsing of sensitive products (crystal glass glasses, etc.). By pointing out that they prevent excess steam from spreading when opened, they highlight these products as environmentally friendly and value-adding compared to conventional household products. In this work, we developed a new commercial dishwasher prototype using a mineral in the drying process. Technical simulations and experiments are used during the development of our innovative prototype with a drying system using a mineral that stores moisture and converts it into thermal energy. This is the first prototype in commercial dishwashers with its innovative drying system.

  • TECHNOLOGIES

    • Development and computer modeling of a new forging technology in step-wedge strikers

      pg(s) 226-229

      A computer simulation of the broaching of the workpiece in step-wedge-shaped strikers of the first and second configurations was carried out by the finite element method. The comparison was made according to the following parameters of the stress-strain state: equivalent strain, average hydrostatic pressure, damage criterion, as well as the deformation force. A comparative analysis of the stress – strain state showed that the second configuration of step-wedge-shaped strikers is the most optimal option for implementing the process of broaching rectangular or square blanks. When using them, a more uniform distribution of the stress state is realized, the deformation processing is sufficiently realized in comparison with the broaching in step-wedge-shaped strikers of the first configuration

    • Design and mechanical properties of high-voltage transmission line composite insulators

      pg(s) 230-233

      Design of high-voltage insulators with a capacity of 12 kV and 24 kV according to standard specifications and determination of the mechanical properties in virtual environment, as well as verification and validation of the results in laboratory conditions was the aim of this paper. The composition of the insulators was 50 vol. % epoxy resin and 50 vol. % SiO2. Based on the physical and mechanical parameters of high-voltage insulators, 3D models were generated to correlate with them. Virtual simulations of the optimized models were performed by using SolidWorks software based on Finite Element Method. In order to re-examine the results, laboratory tests on physical specimens for determination of tensile, compression and three-point bending strength were conducted. The simulations were positively verified and gave promising results. The research conclusions show that the simulations in virtual environment provide easier and faster design and development of high-voltage  insulators, which is of great importance for power transmission network industry.

    • One of the methods for improving the electrodes cleaning system of the electrostatic precipitator with the purpose of increasing the intensity of checking dust

      pg(s) 234-236

      Electrostatic precipitators are designed for highly efficient cleaning of process gases and aspiration air from solid or liquid particles released during technological processes in various industries. To improve the design of the plate electrostatic precipitator and eliminate its lack of insufficient intensity of shaking of the electrostatic precipitator plates, a design of the system for cleaning electrodes of the electrostatic precipitator based on the prototype was chosen, which provides multilevel shaking (top, bottom, side of the plates) in the process of continuous operation of the plate electrostatic precipitator and increases the intensity of shaking dust from the plates of the electrostatic precipitator.

    • Ecological aspects of metallurgy and mechanical engineering at the beginning of the 21st century

      pg(s) 237-240

      At the beginning of the XXI century the anthropogenic uncontrollable industrial activity continuously disturbs the equilibrium of the planet formed for millions of years. A number of metals of vital importance decrease calamitously or disappear completely. The desire for high profits on behalf of a definite group of people leads to disappearing of fertile areas and whole mountains. This imp oses the sensible part of humanity to undertake measures to return part of the breached balance.
      This elaboration suggests several innovative technologies for use in metallurgy and foundry as well as technologies for mechanical engineering, which ensure saving of material sources and achieve significant ecological effect on the environment.

      The proposed technologies represent a complex of classical and modern methods for obtaining, processing and use of mineral and energy earth resources. Methods for utilization of some metal wastes to obtain fit for use products are also indicated

  • MATERIALS

    • Microcrystallites, granularity and agglomerates of detonation nanodiamonds

      pg(s) 241-243

      Energy-saturated materials are considered to be a source of cheap energy, while detonation synthesis is a new promising form of the basic technology for producing nanodiamonds and other super hard and ceramic nanomaterials. Nanodiamonds is a unique product that combines both the properties of diamond and the advantages of nanostructures. The given work investigated the synthesis products, obtained under industrial conditions, while having detonation of a mixture of trinitrotoluene (TNT) with gecsogen (RDX) and RDX with graphite. The sizes of microcrystallites were, estimated by X-ray diffraction analysis and particle grain size according to the measurement of specific surface area, agglomerate in water suspension after treatment by ultrasound. There was, shown the evolution of nanod iamonds particle sizes and microstructures, both in the primary synthesis products and after enrichment from non-diamond forms of carbon and technological impurities. Changes in the microstructure indicate a high reactivity of nanodiamonds. The obtained results can be useful for studying the mechanism of synthesis and practical application of detonation nanodiamonds.

    • Analysis of the influence of environmental factors on the properties of cellulosic electrical insulating materials

      pg(s) 244-247

      From the practical experience regarding maintenance and service life of power transformers, it is important to know the state of degradation (ageing) of the solid insulation and oil transformer. Therefore, it is important to study and analyse how certain factors influence the dielectric properties of insulating materials used in electrical power transformers. This work proposes the experimental study of the behaviour of cellulose type solid materials used to insulate electrical transformers. The aim was to consider the hygroscopicity of cellulose-based products, the influence of temperature, humidity on the insulation resistance, dielectric strength and proof tracking index (PTI) in humid conditions. Experimental determinations were carried out in the framework of the RENAR accredited laboratory within ICMET Craiova. Experimental results have showed that environmental factors (low temperature -40°C and damp heat steady state for 24 hours at 70°C and relative humidity of 95%) strongly negatively influenced some dielectric properties such as insulation resistance and the PTI.

    • The impact of high voltage electric discharge treatment on the properties of Cu – Al powder mixture

      pg(s) 248-251

      Studies of the impact of high voltage electric discharge (HVED) treatment on the dispersion and phase composition of 87,5 % Al + 12,5 % Cu powder system were performed. It was shown that HVED treatment in kerosene with specific treatment energy of 5 MJ/kg leads to the decrease of mean diameter of treated powder from 15 to 13 μm, and the increase of specific treatment energy leads to the decrease of mean diameter of treated powder from 15 to 6 μm. X-ray diffraction analysis shows that CuAl2 and Al4C3 are synthesized in all considered treatment regimes.
      HVED treatment with increased specific treatment energy leads to the increase of quantity of synthesized Al4C3 phase. The use of “three point – plane” electrode system instead of “point – plane” during HVED treatment of 87,5 % Al + 12,5 % Cu powder system leads to the increase of quantity of synthesized Al4C3 and CuAl2 phases, while the efficiency of powders dispersion slightly decreases. Up to 40% of particles in powder mixture, treated by HVED in kerosene with the use of “three point – plane” electrode system, have diameter close to the diameter of the initial powder mixture