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Bucharest, Romania

Sebesan I.,Polytechnic University of Bucharest | Badea C.-N.,Polytechnic University of Bucharest | Stefan V.,Polytechnic University of Bucharest | Sebesan M.R.,METROREX SA | And 2 more authors.
Journal of the Balkan Tribological Association

The railway vehicle running is accompanied by forced vibration of the sprung mass, the springs may have large amplitudes vibrations that are hazardous to produce the phenomenon of resonance. Oppose this danger damping properties of the material elements of suspension and friction between oscillating masses liaison bodies which in most cases are insufficient. Therefore, in modern vehicles, in which suspension was used without friction spring elements (helical spring, torsion spring) should be introduced shock. They produce strong forces that dissipate vibration energy and thus limit their amplitudes. The freight wagon ride quality is determined by the appropriate choice of the damping characteristics to satisfy both structural and functional parameters of freight wagons as well as its operating system. Using buffers that were designed for a specific type of freight car wagons, the other cars driving leads to compromise their quality. The silencer (shock absorber) must have stable damping characteristics as changing the thermal and operating conditions, susceptibility to damage reduced weight and size and allow easy access for intervention. The vibration dampers are mounted directly between vehicle parts connected by springs (between axle box and the bogie frame and / or between the bogie and vehicle box) or the insertion of a resilient damper shock absorber to protect against excessive dynamic applications. To achieve the desired damping, the dampers directions are mounted vertically, horizontally or obliquely. After the acting principle on freight wagons, in generally it is used the hydraulic dampers (viscous) and friction dampers (for Coulomb friction). Source

Badanac A.,Technical University Gheorghe Asachi | Lupescu O.,Technical University Gheorghe Asachi | Manole V.,Technical University Gheorghe Asachi | Popa S.,SNTFC Cfr Calatori SA
Applied Mechanics and Materials

It is known that the unevenness of the cutting depths during the cutting processes, the different physico-mechanical characteristics of the processed materials, values as well as the parameters variation of the working regimes can lead a wear more or less pronounced of the used cutting tools. The lubricant presence in the cutting area may contribute to the friction and thermal field values reduction, affecting the wear processes. It can be said therefore that, the tools durability is influenced by all these factors, which requires decisions and actions to reduce the tools or/and the cutting inserts wear processes. In case of the cutting inserts are known many researches concerning their coverage with material (ions) by vacuum deposition, using methods as: electric arc evaporation, pulverization, ionic plating and chemical vapor deposition. Researches carried out by authors had consisted in making titanium deposition, in thin layer, on the cutting inserts surface in their hardening purpose. The results obtained consisted in a substantial increase of the durability for the used tools in cutting processes in report to those, whose cutting inserts were coated with titanium. © (2014) Trans Tech Publications, Switzerland. Source

Rotariu C.,Technical University Gheorghe Asachi | Paraschiv D.,Technical University Gheorghe Asachi | Lungu S.,Technical University Gheorghe Asachi | Rusu O.,Technical University Gheorghe Asachi | And 2 more authors.
Applied Mechanics and Materials

In this paper we will elaborate a statistic analysis on the main parameters which influence the tribologic depositions process of thin TiN layers. The deposition of tribologic layers will be executed on the axes of the supercharging turbines at the automobiles made of C120, the maximum allowed thickness being of 1÷1.5μm. The main stages of the TiN coating operation are washing and drying conditions which we relate to adhesion layer deposited titanium and titanium coating process, the process consists of important elements of the TiN coating (Electron heating time-Argon plasma, electron temperature, plasma heating argon for Bias voltage ramp., Bias voltage temperature ramp., temperature ion cleaning time for coating titanium pressure nitrogen temperature) relative to the thickness of the deposited titanium. The operation of coating with a layer of TiN was realized at S.C. “Rulmenți” S.A. Barlad, România, with a DREVA 400 machine tool. © (2014) Trans Tech Publications, Switzerland. Source

Badanac A.,Technical University Gheorghe Asachi | Popa Scurtu R.,Technical University Gheorghe Asachi | Bosoanca G.,Technical University Gheorghe Asachi | Husanu V.,S.C.Rulmenti S.A | Popa S.,SNTFC Cfr Calatori SA
Advanced Materials Research

It is known that in the cutting processes, due to the parameters variation of the working regimes, to the unevenness of the cutting depth, to the physico-mechanical characteristics of the processed material, to the existence or nonexistence of the coolant oiling, can appear more or less an accentuated wear of the cutting tools. All this factors have a dominant and negative influence on the durability, fact that impose being necessary taking into account some measures to increase the values of the cutting tools and/or of theirs cutting inserts durability. In this sense are known various coating by deposition in vacuum researches (vacuum thermal evaporation and condensation from the vapor phase, ionic plating, vapor chemical deposition at low pressure, and so on) of some different filler materials, in thin layers, having protection role for the cutting inserts, to increase the edge hardness to the superficial layer and of the tool locating and clearance surfaces and respectively, of their wear resistance. For this purpose, the authors propose to improve cutting tools durability using the deposition method by ionic plating in vacuum (PVD) of the thin titanium layers, following the cutting tools behavior in operation treated in this way. It was so studied the metal carbide cutting inserts wear variation, coated with a titanium thin layer and it was determinate the cutting inserts durability increasing, in comparison with those untreated. This research is useful for predicting the lifetime of the cutting tools and/or of theirs cutting inserts durability, after the titanium thin layer application, with a significant cost reduction. © (2014) Trans Tech Publications, Switzerland. Source

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