VIRTUAL LABORATORY FOR STUDY OF CONSTRUCTION OF MACHINE TOOLS

MM (Modern Machinery) Science Journal, November_2018
DOI:10.17973/MMSJ.2018_11_2017100
JIRI KROUPA, ZDENEK TUMA, JIRI KOVAR, VLADISLAV SINGULE
Brno University of Technology, Faculty of Mechanical Engineering, Brno, Czech Republic
e-mail: kroupa@fme.vutbr.cz
Abstract
Virtual reality is quickly evolving technology which is starting to push not only in entertainment but also in other disciplines like an automotive, machine or aircraft industry. Due to ever higher teaching demands of these problematics virtual reality is one of the ways how to increase teaching efficiency. This paper aims to create a virtual laboratory with an interactive model of a machine tool. Head-mounted display and controllers from Oculus were used for the visualization and interaction with the machine tool. The interactivity of model lies in the opportunity of assembling and disassembling basic parts of the machine tool to elementary construction parts. This enables to the interested person better and faster understanding of construction problematics of machine tools which contribute to the improvement of the teaching effectiveness.
Keywords: virtual laboratory, virtual reality, machine tools, visualization, education
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NON DESTRUCTIVE EVALUATION OF SURFACES AFTER HARD MILLING

MM (Modern Machinery) Science Journal, November_2018
DOI:10.17973/MMSJ.2018_11_201815
MIROSLAV NESLUSAN1, MARIA CILLIKOVA1, PAVEL KEJZLAR2, JURAJ URICEK1
1University of Žilina, Faculty of Mechanical Engineering, Žilina, Slovak Republic
2Technical University in Liberec, Liberec, Czech Republic

e-mail:miroslav.neslusan@fstroj.uniza.sk
Abstract
Grinding operations are sometimes replaced with hard turning or milling cycles. Mechanism of chip separation during grinding and the corresponding surface integrity remarkably differs from hard turning or milling. For this reason, this paper deals with application of Barkhausen noise for evaluation of surface anisotropy after hard milling. Experiments were carried out on hardened bearing steel 100CrMn6. The analysis contains comparison of RMS values for the different hardness and tool wear after hard milling and also discusses the specific mechanism of BW motion in the case of cyclic magnetization. The paper also discusses significance of surface state after hard milling from the point of view of the consecutive technological operations.
Keywords: barkhausen noise, milling, surface integrity, white layer, wear
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POLYNOMIAL INTERPOLATION IN 5-AXIS MILLING

MM (Modern Machinery) Science Journal, November_2018
DOI:10.17973/MMSJ.2018_11_201816
PETRA OHNISTOVA, MIROSLAV PISKA, DAVID PRAT
Brno University of Technology, Faculty of Mechanical Engineering, Institute of Manufacturing Technology, Czech Republic
e-mail: petra.ohnistova@vutbr.cz
Abstract
This study is an introduction to the five-axis milling using polynomial interpolation approach. Progressive milling technologies using different spline interpolations in the control system Sinumerik 840D were compared for a defined number and distributions of the controls points of a planar curve. A tool trajectory for the five-axis CNC milling of a concave profile was generated as the superposition of the third order polynomials, that had been generated with a special algorithm in Mathematica.
Keywords: polynomial interpolation, spline, control system, control point, milling
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INVESTIGATION OF THE INFLUENCE OF PVD COATINGS FOR DRY GROOVE MILLING

MM (Modern Machinery) Science Journal, November_2018
DOI:10.17973/MMSJ.2018_11_201817
ALES JAROS, JOSEF SEDLAK, JIRI VONDRA
Brno University of Technology, Faculty of Mechanical Engineering, Institute of Manufacturing Technology, Brno, Czech Republic
e-mail: jaros.a@fme.vutbr.cz
Abstract
This paper deals with the benefits of PVD coatings applied to HSS three edges end milling cutter. Three types of PVD coatings ((Al,Ti)N, (Al,Ti,Cr)N and nanocomposite nACo) were used to extend the tool life. The coatings were synthesized by a cathodic-arc deposition process. Machining was carried out on the vertical milling machine FB 32V without using process liquid. Set up cutting conditions were constant throughout the machining and tool steel called as Stabil steel DIN 90MnCrV8 (W. Nr. 1.2842) was used as workpiece material. The aim of this experiment was to compare coated and uncoated HSS milling cutters and find out the benefits of PVD coatings during groove milling. The monitored parameters were force loading measured by piezoeletrical dynamometer Kistler 9257B and flank wear measured by tool microscope Alicona.
Keywords: high-speed steel, groove milling, PVD coatings, force loading, flank wear
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ANALYSIS OF MATERIAL REMOVAL ON RADIAL COMPRESSOR WHEEL OF AIRCRAFT ENGINE AFTER FINISHING PRODUCTION OPERATIONS USING CMM

MM (Modern Machinery) Science Journal, November_2018
DOI:10.17973/MMSJ.2018_11_201818
PETR MIKES, LIBOR BERANEK, ZDENEK PITRMUC
Department of Machining, Process Planning and Metrology, Faculty of Mechanical Engineering, Czech Technical University in Prague
e-mail: p.mikes@fs.cvut.cz
Abstract
This paper deals with the dimensional analysis of the turboprop aircraft engine radial compressor wheel. The radial compressor wheel is very complex component. This part is manufactured by turning and five-axis milling technology. Due to the high stress of this part in service life, the residual stress in the surface layer is important. Desirable are the compressive stress levels to prevent cracks. For this reason, research is being carried out on technologies that influence the surface layer. They are the finishing technologies vibrational tumbling and superfinishing. The article describes the method used to measure the thickness variation of blade of the compressor wheel after vibrational tumbling and superfinishing. In terms of shape complexity a coordinate measuring machine with a rotary table was used.
Keywords: coordinate Measuring Machine, compressor wheel, finishing technology
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DIRECT MILLING ON CNC CAROUSEL

MM (Modern Machinery) Science Journal, November_2018
DOI:10.17973/MMSJ.2018_11_201820
KAREL OSICKA, MILAN KALIVODA, MILAN DVORAK
Brno, University of Technology, Faculty of Mechanical Engineering, Institute of Manufacturing Technology, Brno, Czech Republic
e-mail: osicka@fme.vutbr.cz
Abstract
The article discusses an application of new possibilities for the older type of machine. This machine is a heavy vertical lathe in the single column design (series carousel SKJ) which after modernization has a new CNC control system. It has a generally wide range of standardized machining cycles, which are determined not only for carousels. When upgrading the system usually not all software on the machine is operational. That would be useless and expensive. Limited possibilities of the original carousel are then enhanced by the software. In particular, it is the machining of non-rotating surfaces on rotary components. Longer production cycle shorten time because there is no need to move the direct machining to another machine. The operation of these heavy machines are energy-intensive, so the use of advances positively influence the economy of production.
Keywords: carousel, adjustable rotation axis, milling, CNC system, Sinumerik,  cartesian coordinates
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RESIDUAL STRESS WHEN FACE MILLING ALUMINIUM ALLOYS

MM (Modern Machinery) Science Journal, November_2018
DOI:10.17973/MMSJ.2018_11_201821
JOSEF SEDLAK, PETR OSICKA, JOSEF CHLADIL, ALES JAROS, ALES POLZER
Brno, University of Technology, Faculty of Mechanical Engineering, Institute of Manufacturing Technology, Brno, Czech Republic
e-mail: sedlak@fme.vutbr.cz
Abstract
The contribution analyzes the causes of the residual stress in the material during face milling. It focuses on characteristics of internal tension in materials (causes of occurrence, consequences), influence of cutting conditions, machining strategy and possibilities of removal / elimination of internal tension. The experimental section of this article deals with the measurement of internal stresses during face milling of samples (comparison of the aluminium alloys of groups 5th, 6th and 7th) before and after the heat treatment using the method of drilling holes using tensometric rosettes. Part of the contribution is also devoted to the comparision of milling tool diameter influence on the machined surface of sample flatness. The article ends with a discussion that evaluates the achieved results from a practical point of view, an overall conclusion of the results achieved with the problems that arose during the measurement and the final recommendation.
Keywords: residual stress, internal tension, face milling, aluminium alloys, hole-drilling method
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SHOULDER END MILLS WITH PCD INSERTS SHARPENED BY DIFFERENT ELECTRICAL TECHNOLOGIES

MM (Modern Machinery) Science Journal, November_2018
DOI:10.17973/MMSJ.2018_11_201822
TOMAS TRCKA, ALES POLZER, JOSEF SEDLAK
Brno University of Technology, Faculty of Mechanical Engineering, Brno, Czech Republic
e-mail: 153306@vutbr.cz
Abstract
Diamond materials are increasingly used in machining processes as a cutting material, due to their specific properties. Nowadays, is a natural diamond successively replaced by an man-made - synthetic diamond, what also increases their availability. The most used diamond material for milling operations is a synthetic polycrystalline diamond (PCD) produced by HPHT (high-pressure high-temperature) process, because the high fracture toughness of the tool during milling is required [DAVIS 1995] [Tso 2002]. In this work, five end mills with PCD brazed inserts sharpened by different electrical technologies were designed and then produced for the experiment. Three end mills were sharpened by Electrical Discharge Machining – Grinding and the remaining two by WEDM. The comparison of these technologies of sharpening was investigated. At the end of the experiment, the temperatures in the cutting area were determined by a temperature measurement and a different geometry of the tools was also evaluated. This was based on the force loading of the tools measured by the piezoelectric dynamometer 9257B.
Keywords: PCD, electrical technologies, force loading, temperature measurement, tool geometry
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COMPARING THE PERFORMANCE OF MICRO-END MILLS WHEN MICRO-MILLING OF ADDITIVE MANUFACTURED TI-6AL-4V TITANIUM ALLOY

MM (Modern Machinery) Science Journal, November_2018
DOI:10.17973/MMSJ.2018_11_201823
ZDENKA RYSAVA1, STEFANIA BRUSCHI1, MIROSLAV PISKA2, JAN ZIDEK2
1Department of Industrial Engineering, University of Padova, Italy
2Institute of Manufacturing Technology, Brno University of Technlogy, Czech Republic

e-mail:piska@fme.vutbr.cz
Abstract
The objective of this work is to compare the performance of uncoated micro-end-mills and their effect on micro-milling of the Ti6Al4V titanium alloy that had been manufactured in the technology of Additive Manufacturing (AM). In this work, two different geometries of square-end micro-mills with two and fourcutting fluteshave been used. The effective tool geometry at the real micro-machining is rather problematic, because most of the tools are just down-scaled dimensions of standard cutters, so the cutting geometries might not be working well for all dimensions. The Ti6Al4V titanium alloy was made in technologyof Direct Metal Laser Sintering (DMLS). Micro-milling tests were done with use of high precision 5-axis KuglerTM micro-milling centre under dry cutting conditions. The performances were evaluated in terms of surface topography, burrs formation, surface integrity and tool wear.
Keywords: micro-milling, additive manufacturing, surface integrity, micro-end mills
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USAGE OF THE FUZZY LOGIC TO PREDICT SURFACE QUALITY OF MACHINED PARTS DURING MILLING OPEARTION

MM (Modern Machinery) Science Journal, November_2018
DOI:10.17973/MMSJ.2018_11_201824
JAN STREJCEK, LIBOR ZAK, JAKUB DVORAK
Brno University of Technology, Faculty of Mechanical Engineering, Brno, Czech Republic
e-mail: strejcek@fme.vutbr.cz; zak.l@fme.vutbr.cz
Abstract
High level of the quality requirements of machined parts is the standard, which is not unique only for automotive industry, but in industry general. The quality of the product surface roughness is key parameter for every machined product, one of the process with the high influence to surface  quality is the milling process. In this article is used fuzzy logic to predict the surface quality by milling operation. Based on milling process parameters and measured data, the surface quality will be estimated using the Fuzzy Inference System (FIS).
The result shows, that selected fuzzy model can be used to predict surface quality with the selected process parameters.  Finally this study can bring cost evaluation during tool selection and  machine set up parameters.
Keywords: quality, fuzzy logic, surface, tool, parameter
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INFLUENCE OF END MILL VARIABLE PITCH ON SURFACE QUALITY OF ALUMINIUM THIN-WALLED PARTS

MM (Modern Machinery) Science Journal, November_2018
DOI:10.17973/MMSJ.2018_11_201827
IVAN BURANSKY, MATEJ BRACIK, VLADIMIR SIMNA, TOMAS VOPAT
Slovak University of Technology in Bratislava, Faculty of Materials Science and Technology in Trnava, Trnava, Slovak Republic
e-mail: ivan.buransky@stuba.sk
Abstract
In this paper the effect of the end mill variable pitch on the flatness and surface quality of aluminium (EN AW 6082) thin-walled partswas studied. Tests were performed using the HSC 105 linear CNC machine and following cutting parameters: cutting speeds (800, 100, 1200 and 1400 m.min-1), feed per tooth (0.12 mm), cutting depth (for roughing 10 mm and for finishing 5 mm). Three teethsolid end millsof 12mm diameter with a regular pitch of120° and an irregular pitch of 125°, 130° and 135° were used. Surface analysis of the processed thin-walled parts showed that both the irregular pitch of the end mills and the used cutting speed have a significant influence on the surfacequality of the thin-walled parts. The best results were obtained in the case of 130°, 135°irregular pitch end mills and cutting speed 800 and1000 m.min-1.
Keywords: milling, irregular pitch end mills, aluminium thin-walled parts, 3D scanning, colour deviation map, flatness
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DEVELOPMENT OF A VALVE FOR A BRAKING-TORQUE CONTROL USED ON RAILWAY BRAKES

MM (Modern Machinery) Science Journal, November_2018
DOI:10.17973/MMSJ.2018_11_201834
PATRIK BORDOVSKY, PHILIP AMOS MERKEL, HBERTUS MURRENHOFF, OLIVER REINERTZ, KATHARINA SCHMITZ
IFAS - Institute for Fluid Power Drives and Systems, RWTH Aachen University, Aachen, Germany
e-mail: Patrik.Bordovsky@ifas.rwth-aachen.de
Abstract
A novel hydraulic disc brake system with a closed-loop control of the braking torque is under development at the Institute for Fluid Power Drives and Systems (ifas) of RWTH Aachen University. During the braking process, the torque on the caliper acts on a supporting rod. It has been found that the resulting supporting force is proportional to the braking torque. Thus, this force is utilized as a feedback variable for a hydro-mechanical control unit.
In this paper, a simulation model of a spring-applied disc brake is introduced and the behavior of this brake is investigated. Based on those results, necessary requirements on the control unit are deduced and a suitable prototype for the investigation on a test rig is developed. Finally, the behavior of the control unit is analyzed using the simulation model.
Keywords: spring-applied disc brake, hydro-mechanical braking-torque control, valve design, railway application, simulation
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PRODUCTION QUALITY IMPROVEMENT BASED ON 1D DIGITAL TWIN

MM (Modern Machinery) Science Journal, November_2018
DOI:10.17973/MMSJ.2018_11_201839
JOZEF MICIETA, PETR CHLEBANA, MICHAL MASNY, PETER, KRISSAK
Danfoss Power Solutions a.s., Povazska Bystrica, Slovak Republic

e-mail: jmicieta@danfoss.com
Abstract
One of key component of hydrostatic close circuit pump or motor is hydrostatic control. The control influences their performance and behavior. That is the reason to pay high attention on the qualitative aspects. One of them is the First Pass Yield (FPY) indicator.The aim of the paper is to show simulation deployment into the problem solving of leakage issue. High leakages caused low FPY indicator at production line tests. A digital twin was fundamental source of useful information. Selection and finding out the most influencing parameters were based on sensitivity analysis and correlation with the test data and production processes. Final parameters have been found out from their combinations itself in relation to the machining. Outcome of the analysis leads to quality improvement of machining. This improvement of production process of hydrostatic controls resulted to increase FPY indicator close to 100% and reduce its variation into almost 0%.
Keywords: hydrostatic control, sensitivity analysis, simulation, digital twin, leakage
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MACHINE TOOL VIBRATION REDUCTION USING HYDROSTATIC GUIDEWAY

MM (Modern Machinery) Science Journal, November_2018
DOI:10.17973/MMSJ.2018_11_201843
TOMAS LAZAK, MATEJ SULITKA, EDUARD STACH
Czech Technical University in Prague, Faculty of Mechanical engineering, RCMT, Prague, Czech Republic
e-mail: t.lazak@rcmt.cvut.cz
Abstract
Utility properties of the machine tools, such as machining accuracy, surface quality, and productivity are affected by many factors that also include guideway properties. Guideways enable machine tool parts to move. It is generally understood that hydrostatic guideways exhibit better damping properties than linear guideways with rolling elements. However, quantitative expressions of better damping appear in the literature very sporadically. Therefore, this paper presents a model of hydrostatic guideway damping, that include squeeze damping of the thin layer of oil. Furthermore, hydrostatic and linear guideways damping properties are compared on a model example of a large machine tool. Results indicate that hydrostatic guideway reduces the forced oscillation amplitude of the first eigenfrequency 15 times in case of the modeled machine tool.
Keywords: hydrostatic guideway, squeeze damping, vibration attenuation, machine tool
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HIGH PRESSURE HYDRAULICS IN DIESEL ENGINE FUEL SYSTEM

MM (Modern Machinery) Science Journal, November_2018
DOI:10.17973/MMSJ.2018_11_201847
VACLAV VONDRACEK1, ZDENEK TROJAN1, MIROSLAV MALY2
1Bosch Diesel, s.r.o., Jihlava, Czech Republic
2Technická univerzita v Liberci, Liberec, Czech Republic

e-mail: Vaclav.Vondracek@cz.bosch.com
Abstract
The use of high-pressure fuel injection with ultra-fast actuators provides an opportunity for flexible molding of injection parameters, not only for the corect size of the fuel batch, but also in terms of very precise timing. These are good preconditions for optimizing the combustion process and improving of engine performance parameters
Keywords: fuel distribution, injection system, injector
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LNU-FUZZY NETWORK AS A MATHEMATICAL ADAPTIVE MODEL OF A HYDRAULIC SYSTEM

MM (Modern Machinery) Science Journal, November_2018
DOI:10.17973/MMSJ.2018_11_201856
MARTIN VESELY
FMV Design, Czech Technical University in Prague, Faculty of Mechanical Engineering, Department of Instrumentation and Control Engineering, Prague, Czech Republic

e-mail: mveselymartin@hotmail.com
Abstract
Model adaptive controllers such as Model Predictive Control or Model Reference Adaptive Control need a precise mathematical model of the controlled system adaptable in real-time. Systems consisting of a hydraulic 4-way proportional valve and a linear motor have non-linear behaviour such as hysteresis of and valve, death zone of a valve spool, time delay of a data transfer and control unit, dependence on coils temperature and oil temperature and nonlinear flow characteristics. This paper introduces modified Neuro-Fuzzy network as a mathematical adaptive model of a hydraulic system with above mentioned properties. The paper presents the basic architecture of Neuro-Fuzzy network which consists of artificial neural units a fuzzy layer and introduces modifications focused on identification. The basic real-time learning method such as Normalized Gradient Descent is introduced specially for the designed Neuro-Fuzzy Network. Identification and real time learning abilities of the model were tested on the hydraulic stand.
Keywords: neuro-fuzzy network, 4-way proportional valve, adaptive model
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EXPERIMENTAL TESTING OF STEEL WIRE ROPES

MM (Modern Machinery) Science Journal, November_2018
DOI:10.17973/MMSJ.2018_11_201857
MARIANNA TOMASKOVA
Faculty of Mechanical Engineering, Department of Safety and Quality, Technical University of Kosice, Kosice, Slovak Republic
e-mail: marianna.tomaskova@tuke.sk
Abstract
The construction of the steel rope is a complex set which characteristic features, functional ability and life are based on the co-ordination of the separate elements from which the rope is made - steel wires. The paper is focused on fatigue testing of steel ropes. After the fatigue tests, the properties of the wire material, rope erasure and wire strength were determined. Steel ropes were subjected to a cyclically tensile and bending test during the test, while the sample is rotated around the axle to ensure a uniform wear on the surface of the rope. For specific steel wire tests, the mechanical tests of wires from the fatigue straps and the positive influence of lubrication on steel ropes were evaluated by the Cpk Index. Lubrication creates an oil film between the wires, which reduces the internal friction between the wires and prevents the formation of premature notches on the wires that are the cause of fatigue wire breaks.
Keywords: steel wire rope, mechanical tests, competence coefficient
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USAGE OF TOPOLOGICAL OPTIMIZATION IN DESIGN OF MECHANICAL FORGING PRESSES

MM (Modern Machinery) Science Journal, November_2018
DOI:10.17973/MMSJ.2018_11_201877
KAREL RAZ, MILAN CECHURA
University of West Bohemia, Faculty of Mechanical Engineering, Regional Technological Institute, Pilsen, Czech Republic
e-mail: kraz@rti.zcu.cz
Abstract
This article deals with the usage of topological optimization method in the design of mechanical forging press. This area of industry is worldwide without significant development changes for long time. Topological optimization is used here for minimizing weight of forging press and maximizing stiffness of whole machine. Mechanical press with nominal force 80 MNis used as an example.  Frame of press is made from two separate crossbeams and two preloaded columns. The article describes application of optimization methods for welded and also for casted frame of press. Remodeling and verification is performed for welded steel frame.Three optimization tools (FEM codes Tosca, NX Nastran and Frustum) were used for optimization.Main focus is here on upper and lower crossbeam. Optimization theory and parameters (design area, design objective and design variables) are described here from computational point of view. Method called “compliance” and “weight minimizing”was used with respect to considered machine. The simulation model for optimization is considering whole assembly of forging press. Submodeling was used as second step for refinement of results. Loading cases were considering centric and eccentric loading of press. All results were used to create new design of crossbeams for mechanical forging press with nominal forging force 80 MN.
Keywords: mechanical press, topological optimization, deformation, weight, forging
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