Volume 7, Issue 1, 2012/Journal Proceedings in Manufacturing Systems

Abstract: The productivity improvement, especially in the manufacturing industries helps to reduce the cost and further it assists the firms to be competitive in the market. One of the tools which help the industries to reduce cost, manufacturing lead time and defective products is process modeling. Hence, the present day’s need of the market to achieve the quality with the reduction in cost is possible with the effective utilization of modeling tools. Many modeling and simulation tools are available to simulate manufacturing processes. In the present paper, both conventional regression tools (Design of Experiments, Response Surface Methodology) as well as un-conventional modeling tools based on Neural Networks (Back Propagation Neural Network and Genetic-Neural Network) are discussed. All manufacturing processes can be represented as multi input multi output system. It is important to understand the influence of process variables and establish input-output relationships. Design of Experiments combined with Response Surface Methodology is a powerful statistical tool to analyze the influence of process variables and establish accurate input-output relationships. The requirement of manufacturing processes is to know a set of process variables, which will result in desired output (Reverse mapping). However, most of the times the statistical tools fail in reverse mapping. Hence, the use of soft computing based Neural Network, Genetic Algorithm, Fuzzy Logic and their different combinations can be successfully used in reverse mappings. The application of these tools is illustrated with the help of a case study.

Key words: Modeling, Manufacturing Process, DOE, RSM, NN, GA, FLC.

p. 199-204

PROFILING OF A DISC CUTTER FOR CUTTING LARGE WHEELS

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Yulian MLADENOV¹^*, Desislava ATANASOVA², Ivo ATANASOV³

¹⁾ Prof., PhD, Lecturer, Department of MTM, Ruse University, Ruse, Bulgaria

²⁾ Assoc. Prof., PhD, Lecturer, Department of IIT, Ruse University, Ruse, Bulgaria

Abstract: This article shows a principled approach through application of the method of wrapping the treated surface in its variety - a method of coating design - to profiling the work of the disc cutter for cutting gears with larger modules (m≥10mm). Their requirements for accuracy and roughness of the gears’ side surfaces are not very high, due to the nature of work, as they are used to drive different types of drums in the cement, mining, food and other industries.

This profiling approach allows to be manufactured a prefabricated disk cutter, which has some very important advantages, such as lower manufacturing cost, simple forms of the body and teeth (usually plane and rotational), better productivity, which is a result of sharply ground teeth.

In the paper is also shown a construction of a disk prefabricated cutter, designed by the authors, which is used for milling of teeth of a gear with module 20 mm (m = 20 mm).

Key words: cylindrical gear, disc cutter, large modules, profiling, structural wrapping method.

p. 205-210

FAMILY TOOLS FOR ROBOT-ASSISTED LAPAROSCOPY

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Veronika IVANOVA^1,*, Krassimira KOLEVA², Radko MIHAILOV³, Iossif BENIOZEF⁴

¹⁾ (PhD student), Department of Robotized executive mechanisms and Intelligent Systems, Institute of Systems Engineering and Robotics Bulgarian Academy of Sciences, Sofia, Bulgaria

²⁾Assistant Department of Technical Mechanics, The Technical University of Varna, Varna, Bulgaria

³⁾Asoc. Professor, College of Technology to The Technical University of Varna, Dobrich, Bulgaria

⁴⁾Engineer, Department of Robotized executive mechanisms and Intelligent Systems Institute of Systems Engineering and Robotics Bulgarian Academy of Sciences, Sofia, Bulgaria

Abstract: Laparoscopic surgery rapidly evolves as minimally invasive surgery. The lack of the tactile sense is the most important disadvantage associated with laparoscopy because it limits surgeon abilities to diagnoses and treatment some surgical problems. The introduction of robots in minimally invasive surgery will considerably enhance the accuracy of medical interventions. But investigations of current robot instruments are indicated to have some technological deficiencies the main of which are lack of tactile sense. Research in the area of laparoscopic tools with force measurement capabilities has led to significant advancements over the past several years. Researchers have retrofitted conventional laparoscopic instruments with force and position sensors, developed novel laparoscopic tool with sensors incorporated into their design, and have also developed entire robotic surgical systems with force sensing/reflection capabilities. Several researchers have also incorporated a direct sensing method for tissue characterization through pressure measurement normal to the surface of the jaws. These methods are expensive, none sterilizable and not modular which make them difficult to incorporate into laparoscopic tools. To avoid cardinal problems in direct force measurements in bloodless surgery a mechanical construction was produced where two force sensors by Honeywell USA were incorporated. Our work focuses on design of novel surgical instrument for laparoscopic Cholecystectomy with force feedback control and sensors which are incorporated in handle of tool. The paper shows also some variants of rigid and elastic links for irregular objects manipulations.

Key words: end effectors, haptics, surgical robots, instruments, laparoscopy.

p. 211-216

PRE-TENSIONED C-FRAME FOR THE CRANK MECHANICAL PRESS.
STUDY OF THE stress AND strain STATE

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Ioan DAN^1,*, Romeo CIOARĂ²

¹⁾ PhD student, Eng., Transilvania University of Brasov, Braşov, Romania

²⁾ Prof., PhD, Eng., Economic Engineering and Production Systems Department, Transilvania University of Brasov, Braşov, Romania

Abstract: Considering the long useful life duration of the presses, the reduction of their energetic consumption during exploitation turns into an essential goal. An important path for attaining this objective is raising the rigidity of the press, which equals the consumed energy for the elastic deformation of the machine. The paper herein submits such a new solution of C-frame, achieved through casting and being pre-tensioned. The C-frame of the Romanian crank press PAI 25 was taken as reference, whose general geometrical features were not modified. Modelling the reference C-frame and the new constructive solution was accomplished within the design environment ProEngineering WildFire 4. Both models were subjected to the analysis with finite element, resorting to Catia V5 R16, for determining their stress and strain state. The new constructive solution, adequate to pre-tensioning the front pillars of the machine frame resulted from minimally modifying the reference constructive solution. The front pillars were very little modified in order to be tensioned through tightening with tension-rods. For the study of the strain and deformation state, impelling and straining with external forces were stipulated in full accord with the real case. The study was achieved for three values of the pre-strain generated by every tension-rod.

The paper herein submits a few results obtained with respect to raising the rigidity of the machine frame and to reducing the tension state within its body, through pre-tensioning its front pillars. The compared analysis of the results clearly enhances the superiority of the new solution.

Key words: rigidity, pre-tensioned C-frame, mechanical press, FEA, stress state, strain state.

p. 217-222

DIAGNOSE OF HUMAN RESOURCES

OF SMALL AND MIDDLE SIZE ENTERPRISES (SME)

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Nicolae BOIAN^1,*, Marioara Adriana BOIAN²

¹⁾ PhD, Lecturer, department of Engineering Technology and Industrial Management, University “Transilvania”, Brasov, Romania

²⁾ Head of financial accounting department, Financial Investment Company “Transilvania” SA, Brasov, Romania

Abstract: The paper presents the main elements of human resources diagnose as part of small enterprise resources analysis. Starting from general knowledge regarding human resources, the diagnose objectives and specific demands for small and middle size enterprise, this paper synthesizes a model to be used in diagnose analysis process. According to this model, we established a method of evaluation for each of the three topics of human resources analysis: structure, efficiency and behaviour. For each of these we have tables with the main financial indicators.

A scoring evaluation method is associated to this diagnose model to facilitate setting the business level in accordance to human resources criterion. The score function with variables, coefficients and the main coordinates of their choice is also presented. Following the diagnose score, the business level is established and we suggest the main methods of improvement regarding technical resources.

Finally, the paper presents a case study of a company in the field of production, we assessed the business rate and set the main conclusion following diagnose. We added the tables containing values of indicators for the three topics and also the justification for the choice of coefficients significance and conventional score assigned for each domain of analysis.

Key words: human resources, personnel, diagnose analysis, professional competences, labour productivity, labour efficiency, salary.

p. 223-228

APPLYING PRINCIPLES OF AXIOMATIC DESIGN

IN THE CASE OF A DEVICE FOR ROTATIONAL MOLDING

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Laurenţiu SLĂTINEANU¹, Oana DODUN², Margareta COTEAŢĂ^3,*,

Maricela POIENARU⁴, Alina OANCEA⁴, Irina BEŞLIU⁵

¹⁾Prof., PhD, Department of Machine Manufacturing Technology, “Gheorghe Asachi” Technical University of Iaşi, Romania

²⁾Assoc. prof., PhD, Department of Machine Manufacturing Technology, “Gheorghe Asachi” Technical University of Iaşi, Romania

³⁾Lecturer, PhD, Department of Machine Manufacturing Technology, “Gheorghe Asachi” Technical University of Iaşi, Romania

⁴⁾Master student, Department of Machine Manufacturing Technology, “Gheorghe Asachi” Technical University of Iaşi, Romania

⁵⁾Junior Assistant, Department of Mechanics and Technologies, University “Ştefan cel Mare” of Suceava, Romania

Abstract: Axiomatic design is a design method promoted and applied in the last decades in order to help the designer in systemizing his activity, by taking into consideration some essential principles proposed by the Korean scientist Num Suh Pyo et the end of the previous century . On the other hand, the rotational molding is a manufacturing method applied when hollow parts made of plastic are necessary. The method is based on the rotation of the mold around two perpendicular axes. The paper presents the results obtained by taking into consideration the principles of axiomatic design in the case of a device adaptable on a universal lathe. The device is able to facilitate the application and the study of the rotational molding of plastic parts. The placement of the device on a lathe should ensure a simple modification of the rotational speed. Chain and conical gear transmissions were used to obtain the second rotational motion. The analysis developed by means of the stages specific to the axiomatic design facilitated the highlighting of some specific functional requirements and practical solutions for defining the design parameters. A matrix model was conceived by taking into consideration the functional requirements and the design parameters. There were defined three groups of functional requirements; uncoupled and uncoupled solutions were identified. As direct result of applying the principles specific to the axiomatic design, a constructive solution for a device allowing the applying of the rotational molding was proposed.

Key words: axiomatic design, principles, rotational molding, plastic part, device, lathe, motion transmission.

p. 229-234

ANALYSIS OF ENGINE SPEED EFFECT ON THE FOUR - STROKE

GDI ENGINE PERFORMANCE

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Simeon ILIEV^1,*, Kiril HADJIEV²

¹⁾ PhD, Assistant Prof., Internal Combustion Engine Department, University of Rouse, Ruse, Bulgaria

²⁾ PhD, Assistant Prof., Internal Combustion Engine Department, University of Rouse, Ruse, Bulgaria

Abstract: Application of simulation codes on modeling of thermodynamic cycle of ICE has become more important during last years. The computational simulation model development is use for commercialization of computational fluid dynamics software for development of internal combustion engines performance simulation. Advances in physical models, numerical methods and computational power together have brought large-eddy simulations (LES) to the point where it warrants serious consideration for computing in-cylinder turbulent flows. Recently, a simulation tools, which models the different subsystem in an integrated manner has been developed. Analysis of the results of the model make possible investigation of volumetric efficiency, brake efficiency, burning rate, temperature and cylinder pressure value. The numerical analysis and calculations demonstrates that the numerical computational fluid dynamics (CFD) tools, at their stage of development, can help the engine designers to obtain more complete information on direct injection (DI) gasoline engine. For this investigation, a four-cylinder DI gasoline engine was tested under different engine speeds. The present study focuses on the effect of engine speed on engine performance.

Key words: Computational simulation, Engine performance, Gasoline engine, 1D CFD, Spark ignition engine.

p. 235-240

STUDY OF INCREMENTAL DEEP-DRAWING OF BIMETALLIC SHEETS

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Melania TERA^1*, Octavian BOLOGA², Radu BREAZ³, Ionuţ CHERA⁴, Sorin TÎRNOVEAN⁵

¹⁾ Assist.Prof. PhD. Eng, Melania TERA, Industrial Machines and Equipments Department, Faculty of Engineering, "Lucian Blaga" University of Sibiu, Romania

²⁾ Prof.PhD. Eng, Octavian BOLOGA, Industrial Machines and Equipments Department, Faculty of Engineering, "Lucian Blaga" University of Sibiu, Romania

³⁾ Prof. PhD. Eng, Radu BREAZ, Industrial Machines and Equipments Department, Faculty of Engineering, "Lucian Blaga" University of Sibiu, Romania

⁴⁾ PhD Student. Eng, Ionuţ CHERA, Industrial Machines and Equipments Department, Faculty of Engineering, "Lucian Blaga" University of Sibiu, Romania

⁵⁾ PhD Student. Eng, Sorin TÎRNOVEAN, Industrial Machines and Equipments Department, Faculty of Engineering, "Lucian Blaga" University of Sibiu, Romania

Abstract: The usage, as blanks, of bimetallic sheets it’s justified because of the addition of the advantages offered by both materials of which it is composed and to a reduction of the disadvantages presented by each material if taken separately. There are cases in which certain properties are needed on the part's outer side, while on the part's inner side there are needed very different properties. The theoretical researches have targeted the development of models that would allow the analysis through numerical simulation of the behaviour of this type of blanks. Another research direction referred to the manner of generating the shape of parts obtained through the incremental forming process. For the experimental researches there were employed complex trajectories for generating the part's shape. The researches unfolded in this direction targeted a better understanding of the influence of the punch's movement trajectory on the formability degree of bimetallic sheets, as well as on the quality of the realised parts, on the shape errors and on the dimensional precision.

Key words: incremental deep-drawing, bimetallic sheets, numerical simulation, trajectories, spiral.

p. 241-244

NEW INDUSTRIAL ENGINE – PRIORITY AND FIELD OF APPLICATION

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Todor PENCHEV^1,*, Petar BODUROV², Dimitar Karastojanov³

¹⁾ PhD assoc. professor, Material Processing Department, Technical University – Sofia, Sofia, Bulgaria

²⁾ Material Processing Department, Technical University – Sofia, Sofia, Bulgaria

³⁾PhD assoc. professor, Institute of Computing and Comunication Technologies-Bulgarian Academy of Science, Sofia, Bulgaria

Abstract: A new industrial engine is presented – Industrial Rocket Engine (IRE). It was developed in Bulgaria and certified in Russia. That engine is applicable for propelling hammering machines – a high-speed forging hammer and a diesel hammer for pile fixing. Possibilities for broadening the technological capabilities of these machines by the use of IRE are also shown. Better parameters of deformation of special alloys with little plasticity and better parameters in the production of complex shape details were achieved by using such machienes. Using diesel pile-fixing hammer, fixing of piles at any angle can be achieved, very important technique for landslides and earthquake region stabilization. The IRE uses hydrogen (gaseous or liquid) which brings ecological advantage of that industrial engine.

Key words: engine, impact, impact machines, hammers.

p. 245-252

EFFECT OF CUTTING SPEED AND FEED RATE ON TOOL GEOMETRY, TEMPERATURE AND CUTTING FORCES IN MACHINING AISI 1045 CARBON STEEL USING FEM SIMULATION

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Nicoleta LUNGU^1,*, Marian BORZAN²

¹⁾ PhD, Department of Manufacturing Engineering, Faculty of Machine Building, Cluj-Napoca, Romania

²⁾ Prof., PhD, Department of Manufacturing Engineering, Faculty of Machine Building, Cluj-Napoca, Romania

Abstract: Finite element simulation of the cutting process is increasingly used by researches in the field to the detriment of experimental tests because they are expensive and time consuming. Another advantage of this method is that it provides information on deformations, stresses and temperatures that occur during the machining process but also about chip shape and tool wear rate. This paper studies the influence of cutting speed and feed rate on tool geometry, temperature and cutting forces in machining AISI 1045 carbon steel. For this research were run six trials of simulation. The machining parameters (cutting speed and feed rate) were considered variable and tool geometrical parameters were kept constant. Finite element simulation was performed with the software Deform 2D Machining. Simulation results are showing that increasing the cutting speed increases the temperature values but the values of the cutting forces are decreasing. When cutting with high values of the feed rate, cutting forces and temperature are rising, causing modification of the tool geometry and thus a higher wear.

Keywords: finite element simulation, cutting process, feed rate, Deform 2D, cutting forces, tool geometry.

p. 253-258

APPLICATIONS OF THE MONTE CARLO METHOD IN THE MANUFACTURING PROCESSES

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Adrian Stere PARIS^1,*, Ioan TĂNASE², Constantin TÂRCOLEA³, Cristian DRAGOMIRESCU⁴

¹⁾ Assoc. Prof. PhD, Eng., TMS department, University Politehnica, Bucharest, Romania

²⁾ Prof., PhD, Machines and Production Systems Department, University Politehnica, Bucharest, Romania

³⁾ Prof., PhD, Mathematics Department, University Politehnica, Bucharest, Romania

⁴⁾ Assoc. Prof., PhD, Department of Mechanics, University Politehnica, Bucharest, Romania

Abstract: The accelerated developement of computers and software (particularly free and open-source software) made more accessible, for a large category of researchers and engineers, the use of computer aided simulation techniques. In general terms, the Monte Carlo Method (MCM) or Monte Carlo Simulation (MCS) can be used to describe any technique that approximates solutions to quantitative problems through statistical sampling The Monte Carlo simulation has important applications for discret-event systems (usual in manufacturing), stress/strength stochastic modeling (in design), reliability, maintainability and availability evaluation. Simulation in system reliability analysis is based on the MCS method that generates random failure times from each component's failure distribution. As practical exemplification the paper presents a few Monte Carlo simulation procedures and a manufacturing case study.

Key words: simulation, Monte Carlo method, discret-event system, manufacturing.

p. 259-264

Measurement and analysis of CNC machine tool accuracy in different location on work table

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Ivan Kuric^1,*, Matúš Košinár², Miroslav CIsár³

¹⁾PhD, Prof., Eng., Department of Automation and Production Systems, University of Zilina, Slovak Republic

²⁾PhD, Eng, Department of Automation and Production Systems, University of Zilina, Slovak Republic

¹⁾Ing., Eng, Department of Automation and Production Systems, University of Zilina, Slovak Republic

Abstract: Machine tool accuracy is characterized by the ability of the machine to produce parts of the required shape and dimensions keeping the required tolerances and to achieve the desired surface roughness. Requirements for accuracy of the machine tools result from the required precision of components manufactured on the machine. Geometric accuracy of the machine tool is the precision of shape and position of its individual parts and their mutual movements. Accuracy of parts machined on CNC machines depends crucially on the machine accuracy. The paper deals with possibility of geometrical accuracy monitoring of CNC machine tools with Renishaw Ballbar QC 20 in different locations at the work table. Renishaw's QC20 Ballbar is a linear displacement sensor based tool that provides a simple, rapid check of a CNC machine tool's positioning performance to recognized internationals standards. QC20 Ballbar system is a CNC machine tool diagnostic system. It was compared machine accuracy during the operation in three different positions of work table: central, left side, right side at the different speed. It was analysed the accuracy in these different places. The measurement was performed on milling machine tool Haas VF – 4DHEv

Key words: machine toll, diagnostics, roudness deviation, measurement, Ballbar QC20.

p. 265-268

CUTTING EDGE TEMPERATURE PREDICTION USING THE PROCESS SIMULATION WITH DEFORM 3D SOFTWARE PACKAGE

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Ion TĂNASE^1,*, Victor POPOVICI², Gheorghe CEAU³, Nicolae PREDINCEA⁴

¹⁾ Prof., The Machines and Manufactured Systems Department, University “Politehnica” of Bucharest, Romania

²⁾ Prof., The Technology of Materials and Welding Department, University “Politehnica” of Bucharest, Romania

³⁾ Eng., General Logistics Department, Ministry of Administration and Interior, Romania

⁴⁾ Prof., The Machines and Manufactured Systems Department, University “Politehnica” of Bucharest, Romania

Abstract: High speed machining is submitted to economical and ecological constraints. Optimization of cutting processes must increase productivity, reduce tool wear and control residual stresses in the workpiece. Modeling, as close to reality of the cutting process, cannot be done without taking into account thermal phenomena. On the one hand, material mechanical parameters depend greatly on temperature (although it is difficult to obtain actual values of this dependence) and on the other hand, a decisive role is played both by the thermal regime of cutting speed, through component v_g - chip speed tool rake face – and by the amount of heat that occurs in the area of occurrence and formation of the chip. This paper proposes a new approach for describing the friction behaviour at the tool–chip interface in the area near the cutting edge.

Key words: tool-chip interface, cutting models, process simulation 3D, global heat transfer coefficient.

p. 269-267

A NEW APPROACH OF A LENGTH MEASURING SYSTEM IN ORTHOPEDICS USING A LASER PROBE

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Raluca Ioana GUICA^1,*, Cristian DRAGOMIRESCU², Laura Elena TRIFAN³, Constantin Anton MICU⁴

¹⁾ Asist. PhD Student, eng, Faculty of Engineering in Foreign Languages, University “Politehnica” of Bucharest, Bucharest, Romania

²⁾ Conf. PhD, eng, Faculty of Biotechnical Systems Engineering , University “Politehnica” of Bucharest, Bucharest, Romania

³⁾ Asist. PhD Student, eng, Faculty of Engineering in Foreign Languages, University “Politehnica” of Bucharest, Bucharest, Romania

⁴⁾Prof. PhD, eng, Faculty of Mechanics and Mechatronics, University “Politehnica” of Bucharest, Bucharest, Romania

Abstract: This paper aims to present a new model of a length measuring system in orthopedics using a laser probe. A study of the current measuring methods in orthopedics revealed the need of an accurate, easy to use device, whose production or operating costs are not very high, and that doesn’t expose both pacient and doctor to radiation. In order to achieve this requirements several researches upon different possible models were done. The devices are basen on coordinate metrology, that has reached a high level of accuracy. This paper will present one of the theoretical models, trying to define a certain point of the laser beam, so that in any moment, the doctor to be able to measure the distance between two points, thus achieving, for example, the length of a leg. When the best solution will be found, the device will be built and used both in clinical and intraoperative assesment.

Key words: length measuring, laser probe, coordinate measuring machine, orthopedics, leg length discrepancy.

p. 275-279

Study about the FLUID losses IN the branching pipes

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Iulian FLORESCU^1,*, Daniela FLORESCU², Dragos Iulian NEDELCU³

¹⁾ Professor., PhD, Faculty of Engineering, “Vasile Alecsandri” University of Bacau, Romania

²⁾ Associate professor, PhD, Faculty of Engineering, “Vasile Alecsandri” University of Bacau, Romania

³⁾ PhD, Faculty of Engineering, “Vasile Alecsandri” University of Bacau, Romania

Abstract: This paper aims to determine the losses of branched pipe sections according to the ratio of flow areas, inclination of the adjacent pipe, and source flows ratio.

This paper proposes a method for analyzing the dynamics of real fluid flow through pipe bends. The method can contribute to an optimal design of pipe networks. Along with linear load losses, local losses are particularly important for these piping systems, their analysis for determining coefficients of load losses being of prime importance. Besides the classical experimental attempts to study these tests we can try a method of theoretical analysis based on flow simulation, more accessible to different variants of the pipes. The variation of major structural and functional parameters of the flow is emphasized by the simulation of the flow. We can determine areas of hydraulic energy losses and can appreciate the value of the main flow parameters. Simulations were performed using Fluent 6.3 software and digital data were processed for obtaining graphs with Mathcad 14. Piping systems were represented with SolidWorks program. The Flow simulation allows an analysis of current lines, areas of turbulence and highlighting the hydrodynamic parameters of flow.

Key words: fluid loss, dead flow, wavy flow, cross section, input/output flow.

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