Scientific Bulletin Series C, Volume XXXIV (2020)

Instantaneous Squeeze Force in the Case of the Narrow Sliding Radial Bearing
Exposed to Shocks and Vibrations

Ioan Marius Alexandrescu, Radu Cotetiu, Dinu Daraba

Abstract: Theoretical and experimental research is presented regarding the behavior of narrow radial HD bearings in high loading conditions. We determined relationship of carrying capacity in dimensional form for narrow radial HD bearings exposed to shocks and vibrations, the determining relationships of the lubricating minimum thickness in relation to the dynamic loading and pressure distribution from the film to be lubricated in five places of the bearing’s body. Details on the measuring accomplishments and the experimental results are recorded in relation to the results obtained. In the very short time of the shock, we consider only the approach movement between spindle and bushing on direction of the center line, without the rotation of the spindle (the case of the non-rotating bearing), such that the effect of the lubricating expulsion be prevalent in achieving load-bearing capacity.

Keywords: lubricating expulsion, pressure distribution, shock amplitude

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The Theory of Drilling Industrial Plastics

Vladimir Bardai, Mircea Lobonțiu

Abstract: The cutting of industrial plastics has begun to develop a growing interest from companies processing cutting machines in various industries worldwide. The aircraft construction industry, machine manufacturing, civil and military defense have begun to develop the range of products they own and manufacture in their plants, the use of industrial plastics brings a number of significant benefits compared to their metallic materials or alloys. The properties of polymeric materials can be adapted to almost any functional need, so that the attention paid not only in the industrial environment is increasing. The complex parts of these types of materials also require complex processing operations to obtain the desired surface quality, the challenge that occurs in the case of these materials is their melting point, the temperature they reach during drilling.

Keywords: surface roughness; castamide; end milling; cutting edge

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Experimental Results of Heat Flow in the Roof of the Maramures (MM) Tiny House

Adi Ben-Senior, Nicolae Ungureanu, Mihai Banica

Abstract: This paper is presenting the results of the experiment of the heat flow via convection in the roof of the MM tiny house and additional two other reference models. The convection in the roof cavity is highly affected by the angle at the base of the roof. The model and its experimental results provide predicative and quantifiable result of the efficiency performance of the convection in the roof cavity. The method can be used as a new tool for designing a hip roof when one wants to account for thermal performance in addition to architectural and structural considerations. The tool provides a more sustainable design and a real application for passive and NZEB house design.

Keywords: MM tiny house, roof, pitch, convection, heat, speed, time

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Studies and Research on Adhesive Wear of Gears with Pairs of Gears Made of Plastics and Steel

Lucian Butnar, Otto Eberst

Abstract: Steel and plastic twin gear gears are increasingly used in various industrial sectors. They often work in areas where gear lubrication is not possible or very difficult. So, between the sides of the two gears there is a dry friction and intense adhesive wear. The present paper carries out theoretical research on the phenomena from the contact between the sides of the gears and aims to determine, by calculation, the speeds of adhesive wear that occur at each of the two gears that form the gear.

Keywords: adhesive wear, gear, plastic-steel

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Verification of Machine Tools for the Purpose of Remanufacturing

Catalin Daraba, Dinu Daraba, Ioan-Marius Alexandrescu

Abstract: The analysis of technological equipment before remanufacturing through modal analysis involves the determination of the frequencies and vibration modes of their mechanical components. Based on this analysis, information obtained is about the dynamic behavior of the analyzed structure. The decision to remanufacture a machine tools also takes into account the issues related to the dynamic behavior of its structure.

Keywords: machine tools, remanufacturing, modal analysis

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The Romanian Industry and the COVID-19 Pandemic

Raul Florentin Drenta, Dan Adrian Pop

Abstract: The COVID-19 pandemic was a shock for the Romanian economy, starting with March 2020. The Romanian industrial sector was also influenced by the effects generated by the global and national measures taken in order to combat the pandemic. This article aims to analyze the stages of economic evolution of Romanian industry in the first year of the pandemic. It analyzes the possible factors behind the official figures. The analysis uses a series of public data from both the private and institutional spheres, compiled in a chronology of what the COVID-19 effects meant for the Romanian industry. The evolution that is taking place so far follows the letter V pattern with a slight consolidation in the last quarter of 2020. However, in order to sustain this long-term evolution, the industrial sector needs support through well-founded and globally correlated public policies. The main lesson learned is the need to make the value chain more flexible depending on the stage of the pandemic.

Keywords: COVID-19, industry, value system

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Spectral Analysis of the Signal Applied to the Electromechanical Actuators in the Thermal Power Plant Component

Flaviu-Nicolae Kesucz, Nicolae Ungureanu, Mihai Banica

Abstract: The purpose of the scientific research in this paper is the spectral analysis of the signal applied to the
electromechanical actuators from the thermal power plants component through experimental measurements to determine the level of noise and vibrations in operation. Experimental measurements were performed with the signal analyser system, on the Brüel & Kjaer platform for noise and vibration analysis PULSE Diagnostics Toolbox Type 9727, with the PULSE Type 3560-B measurement system and with the Bundle Type 7910 package the basic measurement software is the fast Fourier transform (FFT) analysis and a constant percentage bandwidth filter (CPB) analysis to determine the maximum frequencies, magnitudes in terms of spectral density. The measurements were performed on the solenoid valve produced by SIT Group, model Sigma 845 which includes in its composition the electromechanical actuators EV1 – EV2 which are the object of the study in this scientific paper. The electronic transducers produced by ENDEVCO model TEDS and ISOTRON 752A12 which are piezoelectric accelerometers with integrated electronics, which have electronic data of the IEEE P1451.4 transducer, measure the mechanical oscillation, the dynamic acceleration of a physical device as a voltage, obtaining the amplitude-frequency spectra are at different values of the alternating supply voltage.

Keywords: actuator, analysis, electromechanical, signal, transducer, vibration

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Selected Aspects of the Technology of Broaching of Internal Contoured Surfaces

Jozef Martinovič, Jozef Peterka

Abstract: The technology of broaching is one of the machining methods used in mass production. It is a very rare technology. Its application is very economical and it achieves high quality parameters of machined surfaces. In our paper we describe two selected aspects: 1. the economical aspect – the use of statistical methods in the field of metal chip machining in the technology of broaching of internal contoured surfaces, 2. the technology aspect – the achieved surface roughness of internal contoured surfaces – the groove – in the conditions of mass production.

Keywords: broaching, statistical methods, profile shape, roughness

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Research on the Process Activation Importance to Obtain the Quality of the Processing Surfaces

Alina Bianca Pop, Aurel Mihail Țîțu

Abstract: Electrical erosion is one of the most common methods of processing with concentrated energy. In this way, the sampling method of the material is discontinuously and cumulative. The way in which the activation of dimensional processing is performed is effectively a cumulative result of erosion processes of an elementary and temporary nature and which is spatially concentrated. This concentration takes place between a transfer object and a processing object. In this context, this scientific paper highlights an experimental statistical analysis whose experimental set refers to the processing of sintered hard alloys of type P30. The transfer objects that were used were made of specific materials: electrolytic copper, steel and graphite. In this experimental study was examined the modeling and statistical optimization of some objective functions. These objective functions aim at the process productivity, the transfer objects volume and last but not least the quality of the surface that was processed, measured by the Ra [μm] parameter.

Keywords: electrical erosion, processing object, productivity, statistical analysis, transfer object, quality

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Management Aspects Related to the Optimization of the Technological Operation of Cutting by Electric Erosion with Contact Breaking

Alina Bianca Pop, Aurel Mihail Țîțu

Abstract: This scientific paper presents some aspects related to the management of the optimization of processing operations by electrical erosion with contact breaking. The introductory part contains a series of theoretical considerations on the approached field, highlighting the importance and role of optimizing such a process. The criteria for achieving an optimization process in this way, in the industry, as well as the restrictions imposed by them in optimizing the cutting are also analyzed. In the last part of the research are presented the own points of view and the conclusions derived from this study that point out the need to correlate the technological, mechanical and working parameters in the electrical erosion process. At the same time, the way in which this process can be improved in the sense of creating favorable conditions regarding its stability was highlighted.

Keywords: electrical erosion, operation, optimization, processing object, transfer object

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Open Innovation – The Driver for a Smart, Sustainable and Livable Europe

Sorin Pop, Mircea Lobonțiu, Gabriela Lobonțiu

Abstract: Innovation in Europe, and especially Romania is lagging behind the State of the Art. The European
Commission and policy makers are trying to learn from best practice examples, such as the big corporate models in USA and adapt innovation ecosystems to its specific context. European Universities, Cities, Policy makers are driven to work together in Digital Innovation Hubs, while building ecosystems designed to drive research and innovation to the foreground of European Development. As SME’s are the main pillar for economic growth and Cities are the driver for sustainable social development, Europe’s future depends in leveraging on their adaptability, resources and creativity, while bringing academia, users and communities to the co-creation and co-design table of goods, services and processes. Digital Innovation Hubs and Urban Innovative Actions provide the context for making these actors work together for the common good in a smart, sustainable and livable Europe.

Keywords: Open Innovation, Urban Innovative Action, European Context

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Model of the Surface Roughness Prediction in Turning

Róbert Straka, Jozef Peterka, Jozef Martinovič

Abstract: Surface roughness is one of the parameters thanks to which machining can maintain itself as a competitive method of component production in various areas of industry. By predicting the roughness of the machined surface by simulation, it is possible to improve the surface quality and speed up the process of determining suitable cutting parameters for the production of parts by machining. This article deals with developing a surface roughness prediction model and comparing it to another model for verification of its function.

Keywords: model, surface roughness, turning process, machining

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