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Recent 29

Vol. 11 (2010), No. 2 (29), July 2010

The 29th issue of RECENT journal was edited and multiplied with support of:

  • Transilvania University of Brasov, Romania

  • Romanian Association for Nonconventional Technologies

  • Brasov County Council (by Scientific Activities, Education, Culture, Cults Committee), Romania


CONTENTS


  • Roxana Ionela ARVINTE, Mihai APREUTESEI, Elena Victoriţa CLINCIU

Aspects about Reactive Magnetron Sputtering Deposition Technique

» Abstract

Within the frame of this work the reactive magnetron sputtering technique used for deposition of the thin films was investigated. Magnetron sputtering is a flexible technique which can be used to coat virtually any work piece with a wide range of materials. This technique is one of the most used physical vapour deposition technology in very large areas from industrial applications to jewellery coatings. In the present paper is presented the reactive magnetron sputtering technique and its characteristics.

» Keywords

reactive magnetron sputtering, thin films, PVD technique, magnetrons, plasma

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  • Sorin Adrian BARABAŞ, Eugen Cornel ŞERBAN

Heat Treatment for 20NiCrMo7 and 15CrNi13 Steels Used on Construction of Extra large Bearings

» Abstract

This paper give an overview to the processes appeared in deep carburizing of elements produced with 20NiCrMo7 and 15NiCr13 steels used in construction of hollow rollers. The used software is specialized to simulate heat treat process of carburizing in controlled atmosphere with different level of carbon potential. Experimental measurement of temperatures and carburizing size, during heat treatment, was made as part of this study and confirm theoretical results to validate the software predictions. Mathematical model is based on mass transfer law and Fick second law and the algorithm was implemented in Visual C++. The objective for this work was to develop a strategy for the process control and optimization of heat treatment process.

» Keywords

carburizing, carbon potential, extra-large bearings

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  • Romeo CIOARĂ, Ovidiu SÎRBU

Upon the Ordination of the Gear Ratios in the Bicycle Chain Gearing

» Abstract

Chain gears used for bicycles may be simple, which achieve a single gear ratio, or complex, in which the gear ratio takes several discreet values. Through regulating the gear ratio, the bicycle advancement speed is in fact regulated, in order to make it adequate to the bicyclist’s desire, the road conditions and the power developed at the pedal shaft by the bicyclist. Different bicyclists have different objectives: some of them aim at performance, others use the bicycle for relaxation, and others simply get out of place. Consequently, the maximal value of the power that the bicyclist is able or is willing to develop at the pedal shaft is different from case to case. Therefore, the bicycle gears must be personalized. The paper herein describes the range of speeds likely of being achieved with a bicycle and emphasizes, if there was still the case, that the optimal ordination of the gear ratios must be performed in geometric series. There is shown that the currently used gears in bicycles do not observe this requirement, there is offered a solution for the teeth number of the chain wheels, which sufficiently solves the correct ordination of the gear ratios and there is specified that researches are justified for conceiving and achieving a gear with self-regulating rotational speed.

» Keywords

chain gear, gear ratios, ordination

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  • Dida CONSTANTIN, Daniel MUNTEANU

Theoretical Aspects on some Mechanical and Tribological Properties of MeNx (Me = Ti, Zr, Ta) Thin Films

» Abstract

This paper presents a bibliographical study concerning the mechanical and tribological properties of MeNx type (Me = Ti, Zr, Ta) coatings. Various researches have shown that these types of MeNx compounds revealed good properties in terms of hardness, friction, wear and corrosion aspects. Wishing to extend the practical applicability area of these compounds, in the last time, the researches were focused for finding optimal compositions which could offer the multifunctional character. That means, coating with good mechanical, tribological, electrical, optical and decorative aspects, in a simultaneously mode.

» Keywords

thin–films, transition metal, nitride, hardness, wear, friction

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  • Carmen-Roxana DASCĂLU, Vladimir MĂRĂSCU KLEIN

Consumption of Electricity from Renewable Resources by Households and Industry in Sweden and Romania

» Abstract

Renewable electricity production, from sources such as wind power and solar power, is sometimes criticized for being variable or intermittent. However, the International Energy Agency has stated that deployment of renewable technologies usually increases the diversity of electricity sources and, through local generation, contributes to the flexibility of the system and its resistance to central shocks. Sweden is among the five most important countries of the EU-27 group, followed by Romania on eleven, due to installed capacity for power generation using renewable energy. In both countries, it is interesting to study the share of energy produced using renewable energy in total energy output, the efficiency measures are taken and the selling prices of electricity are applied to household and industrial consumers.

» Keywords

renewable energy, electricity, electricity prices, electricity production, electricity use

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  • Konstantin D. DIMITROV, Dimitar NURKOV

Complex Algorithmic and Software System for Simulation of Technical States on an Experimental Laboratory Platform

» Abstract

The present paper describes the development and the application of a complex and sophisticated algorithmic and software system, which is designed to simulate technical conditions and systems states, which could be generated in a real industrial equipment, (and under real operational conditions), but on a specific experimental laboratory platform, (specially created for the purpose).

» Keywords

algorithmic system, experimental simulation, technical conditions, systems states

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  • Florina-Cristina FILIP, Vladimir MĂRĂSCU KLEIN

Management of Internal and External Logistics Flow of Materials

» Abstract

All models, processes and means of handling, storage, internal transportation, management of raw materials in an enterprise, necessary to developing the production process are considering industrial logistics. For an enterprise, its logistics management system and integration in partner systems, constitutes a strategic advantage. Through its activities, logistics is vital in creating such an advantage, it can positively affect market share and profitability of the undertaking, if is seen as a strategic resource, not only as a simple activity. By this paper is aims reporting logistics at different activities as the planning, management and control the flow of goods and services, people and information. This includes all the necessary steps to achieve timely delivery of products, goods and services from initial point to destination.

» Keywords

supply chain, cross-dock, milk run, internal logistics flow, external logistics flow

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  • Lavinia Nicoleta NEAGOE, Vladimir MĂRĂSCU KLEIN

Quality and Management Tools, an Integrated Approach for Quality Cost Reduction

» Abstract

Successful quality management is dependent on first class problem solving and continuous improvement. Cost control and product quality can sustain the organizational competitive advantage, while the innovation creates it. Both, problem solving and continuous improvement need the same managerial techniques, quality and managerial tools. However, it is difficult to decide which technique should or could be used in different situations and to see how different approaches are related to each other. The article briefly describes the “Seven basic quality tools”, “Advanced quality tools”, “Seven new management tools” and makes the link between different situation and the tool that must be used. Based on ten years of experience in this field of activity in Romanian companies, in the last part of the article are presented the key points for a good implementation and proper use of all this tools.

» Keywords

quality tools, problem solving, quality cost

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  • Tudor PĂUNESCU

Tolerance Optimization of the 2H2P Assembly for Modular Fixtures

» Abstract

The paper presents a stochastic approach to maximize the geometric accuracy of the two pins - two holes (2H2P) assembly. The probability of successful 2H2P assemblies to engineering specifications is calculated using a Monte Carlo simulation. Applying a “Generate and Test” algorithm, the optimal tolerances of modular systems are obtained. The algorithm is applied to optimize the modular fixture systems with grid pattern holes. The results presented in this paper can be useful to the multi-objective modular fixture system optimization or for other engineering applications using 2H2P assembly system.

» Keywords

statistical design, tolerance optimisation, modular fixture system, Monte Carlo simulation

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  • Cosmina PÖLLNER

Constructive Particularities of a Mechanical Vulcanizing Press

» Abstract

The present paper addresses some of the structural and functional features of a mechanical vulcanizing press. Characteristic for this are the two distinct kinematics chains for the motion of the plates: a kinematics chain for rapid lifting/descent, and a kinematics chain for correcting the pressing position. Both of them determine, in different ways, the translation of the same machine part, a grooved screw. Having as reference the kinematics scheme of the press, original, for which has already been requested patent protection, it has been developed a virtual, constructive and functional model in Pro Engineer Wildfire. The virtual modelling of the press’ operation aims so far only to shape the actions of the main elements of the two kinematics chains of the machine.

» Keywords

mechanical vulcanizing press, operation, structural features

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  • Răzvan RĂCEU

Constructive Particularities of an Equatorial Spherical Hypocycloid Automatic Machine

» Abstract

Technical development is one of the paths of human evolution. New technologies and products emerge, are developed and applied, including new types of machine tools. Research made by Transilvania University of Brasov, Romania has led to the elaboration of a new class of automatic presses, called the “hypocycloids”. These exploit some special features of the plain hypocycloid curves and the planetary mechanisms with internal gearing that can generate such trajectories. Latest research has highlighted the possibility of extending this class of machines, in terms of the conception of spatial hypocycloid automatic machines. Research targets so far the spherical hypocycloid automatic machines, highest priority approach receiving / being given to the equatorial ones. In this sense, was already developed a unique, initial concept, for which the patenting procedure has been initiated. Having as reference the kinematic scheme of an equatorial spheric hypocicloid automatic machine, it has been elaborated a constructive and functional virtual model in Pro Engineer Wildfire. The primary scope of this paper is to present some of the structural features of this automatic press in conjunction with the operating principle of this machine.

» Keywords

hypocycloid automatic machine, structural features, kinematics, operation, invention

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  • Luciana -Cristiana STAN

Development of Economic Competitiveness in Industrial Business

» Abstract

Sustainable economic growth and improving living standards of the population are determined by the development of economic competitiveness in the context of global challenges (economic globalization, open international markets, rapid technological change), challenges which must be transformed into opportunities for the Romanian economy. Labour productivity in industry has had an upward trend due to both decrease the number of staff employed, and as a result of investments for modernization and manufacturing flows better organization of work, based on better management. The concept of industrial policy aims at improving competitiveness by boosting performance of companies, focusing on horizontal policies that affect all industry sectors, namely: innovation, new technology and processing equipment, professional skills, education and training, business management.

» Keywords

competitiveness, business, industry, management, industrial engineering

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  • Ciprian Andrei SZABO, Ioan CIOBANU, Vasile JIMAN, Daniel FERARU

Research on the Influence of Thermoinsulating Cores on the Functioning of Feeders (I)

» Abstract

The paper presents the results of a study on the influence of heat insulation of feeders on the solidification of parts cast in silica sand moulds. The study was conducted by computer simulation of casting. The study concerned the influence of feeder diameter and of heat insulation on casting solidification, and further the influence of the thickness of thermoinsulating cores applied at the superior side of feeders on shrinkhole position and directing the solidification of the casting–feeder system.

» Keywords

casting, solidification, feeder, thermoinsulating core

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