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1.
Numerical simulation of conveying fine powders in a screw conveyor using the discrete element method
Marko Motaln, Tone Lerher, 2023, izvirni znanstveni članek

Opis: Due to their high efficiency and spatial utilization, screw conveyors are widely used in pharmacy, agriculture, and industry. Recently, this has made it a popular research subject in the numerical modelling of the transport of bulk solids. Modelling of granular systems at the level of individual particles is mainly possible due to the use of discrete numerical methods. The most common is the use of the Discrete Element Method (DEM), which is still limited from the point of view of simulations on an industrial scale, as increasing the size of the system also increases the cost of simulation. Certain powders with low density, large angles of repose, poor fluidity, and bad flowability can accumulate during transportation, causing inaccurate and non-uniform movement. Additionally, the friction and impact between the particles can cause wear. To address these issues, the present study utilizes the discrete element method to simulate and analyse powder transportation in an inclined screw conveyor using the commercial software ANSYS-ROCKY. Numerous phenomena that arise while transporting and feeding small-sized or irregularly shaped particles, often present in industrial processes, remain insufficiently investigated. This paper aims to analyse the transportation process of adhesive powders in a screw conveyor, with a focus on evaluating the impact of different screw blade speeds on transport. Multiple simulations were conducted, along with the implementation of an additional wear model, to better understand the transport phenomena and wear. An example was used to demonstrate the impact of screw speed on the wear of the transporter due to the interaction between the material and the structure of the conveyor, power consumption, and performance.
Ključne besede: abrasive wear, bulk handling, coarse graining, conveying equipment, discrete element method, screw conveyor
Objavljeno v DKUM: 12.09.2023; Ogledov: 297; Prenosov: 43
.pdf Celotno besedilo (1,69 MB)
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2.
Wear Behaviour of Multilayer Al-PVD-Coated Polymer Gears
Tonica Bončina, Brigita Polanec, Franc Zupanič, Srečko Glodež, 2022, izvirni znanstveni članek

Opis: A comprehensive experimental investigation of the wear behaviour of coated spur polymer gears made of POM is performed in this study. Three different thicknesses of aluminium (Al) coatings were investigated and deposited by the Physical Vapour Deposition (PVD) process. The Al coating was deposited in three steps: By plasma activation, metallisation of the aluminium by the magnetron sputtering process, and plasma polymerisation. The wear of the gears was tested on an in-house developed testing rig for different torques (16, 20, and 24 Nm) and a rotational speed of 1000 rpm. The duration of the experiments was set to 13 h, when the tooth thickness and, consequently, the wear of the tooth flank were recorded. The experimental results showed that the influence of metallisation with aluminium surface coatings on the wear behaviour of the analysed polymer gear is not significantly important. The results also showed that the gears with a thicker aluminium coating showed greater wear than gears with a thinner coating or even without a coating. This is probably due to the fact that the aluminium particles that started to deviate during gear operation represented the abrasive material, which led to the faster wear of the contacting surfaces of the meshing gear flanks.
Ključne besede: polymer gears, aluminium PVD coating, Physical Vapour Deposition process, multilayer coating, wear
Objavljeno v DKUM: 15.11.2022; Ogledov: 402; Prenosov: 49
.pdf Celotno besedilo (13,01 MB)
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3.
Razvoj aplikacij na platformi android wear
Žiga Vehovec, 2017, diplomsko delo

Opis: V diplomskem delu predstavimo pomen nosljivih tehnologij in se osredotočimo na razvoj aplikacij za pametne ure, ki jih poganja Googlov operacijski sistem Android Wear. Predstavimo, kaj platforma omogoča ter njene pomanjkljivosti in omejitve. Z usvojenim znanjem nato razvijemo aplikacijo, ki uporablja vse glavne koncepte razvoja na omenjeni platformi ter prikaže povezavo med platformama Android in Android Wear.
Ključne besede: Nosljive tehnologije, Android, Android Wear, Pametne ure
Objavljeno v DKUM: 27.10.2017; Ogledov: 1893; Prenosov: 141
.pdf Celotno besedilo (2,59 MB)

4.
Casting process optimization by the regression analysis applied on the wear resistant parts molding
Radomir Slavković, Slavko Arsovski, Aleksandar Veg, Zvonimir Jugović, Aleksandar Jovićić, Nedeljko Dučić, 2012, izvirni znanstveni članek

Opis: Conducting a comprehensive research of the casting process of wear resistant parts (white hard casting), a significant correlation is established between the technological parameters (temperature, aging time in the mold and coolant flow) and the final product hardness. The fundamental theory of Box-Wilson's gradient method marked the baseline for the foreseen researches. The method defines the coherence of the process parameters, since their dispersion in the examined process is relatively small. Main target of the experiment was a definition of the optimal casting conditions. Therefore the different technological routes are identified and the casting process is modified until the best outcome is achieved. Target function was initially in a hypothesized form, while later on evolved into a consistent form due to the application of experiment-statistics, process optimization and process management based on empirical feedback.
Ključne besede: casting, mathematical model, quality management, wear resistance
Objavljeno v DKUM: 11.07.2017; Ogledov: 1088; Prenosov: 115
.pdf Celotno besedilo (595,79 KB)
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5.
Simulation of the casting process - a powerfull tool for enchanced design of the cutting teeth in surface mining
Radomir Slavković, Zvonimir Jugović, Dražan Kozak, Aleksandar Veg, Radomir Radiša, Snežana Dragićević, Marko Popović, 2013, izvirni znanstveni članek

Opis: Recent development in the computer simulation technology caused a tremendous influence on a rapid prototyping in casting process. These computational tools facilitate engineering work and urge moulding verification in foundries. Among dedicated software packages the MAGMASoft is selected for availability reasons. Its effectiveness is proved with the simulation of moulding process of the cutting teeth for a bucket wheel excavator Use of MAGMASoft enables a shortcut to a forceful and durable product, without internal cavities and micro-porosity. Such advancement of the moulding process is described in this paper.
Ključne besede: casting, porosity, wear, simulation, MAGMASoft
Objavljeno v DKUM: 03.07.2017; Ogledov: 2216; Prenosov: 138
.pdf Celotno besedilo (1,03 MB)
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6.
Realno-časovna komunikacija mobilnih aplikacij s senzorji
Tomaž Orter, 2016, diplomsko delo

Opis: V diplomskem delu predstavimo tehnologije in protokole, ki omogočajo realno-časovno komunikacijo med mobilnimi aplikacijami in senzorji. Z uporabo protokola MQTT na praktičnem primeru nadzora ogrevanja stanovanja predstavimo njihovo uporabnost in lastnosti. Začnemo z izdelavo senzorja temperature, ki podatke zaznava in sporoča, ter centralnega strežnika, ki jih obdela, se na njih odzove in jih posreduje do končnega odjemalca. Nadaljujemo z izdelavo mobilne aplikacije, ki v tem primeru predstavlja končnega odjemalca. Aplikacija podatke v realnem času prikazuje in uporabniku omogoča nadzor nad ogrevanjem. Mobilno aplikacijo dopolnimo z izdelavo aplikacije za pametno uro. Ta s pomočjo obvestil in lokacijskih podatkov uporabnika opozori na vklop ali izklop varčnega načina ogrevanja. V zaključku dela preverimo, ali smo z uporabo namenske tehnologije uspeli prihraniti na količini prenesenih podatkov in pohitriti njihovo prejemanje.
Ključne besede: Realno-časovna komunikacija, senzorji, internet stvari, nadzor ogrevanja, mobilna aplikacija, MQTT, HTTP, CoAP, AMQP, XMPP, DDS, WiFi, Raspberry Pi, Arduino, Android Wear
Objavljeno v DKUM: 08.09.2016; Ogledov: 1744; Prenosov: 178
.pdf Celotno besedilo (4,05 MB)

7.
PROGRAMSKA OPREMA ZA ANIMIRANJE OBLIK UR IN IZDELAVA FORMATA ZA NJIHOVO SHRANJEVANJE NA PLATFORMI WATCHFACE EDITOR
Damijan Račel, 2015, diplomsko delo

Opis: V diplomskem delu opišemo kako smo načrtovali in implementirali mobilni Android del platforme Watchface Editor. S pomočjo naše platforme lahko uporabniki na spletni strani preprosto ustvarijo oblike ur ali watchface-e, in jih nato preko naše mobilne aplikacije naložijo na pametno uro Android Wear.
Ključne besede: pametna ura, android, wear, pebble, java
Objavljeno v DKUM: 14.10.2015; Ogledov: 768; Prenosov: 84
.pdf Celotno besedilo (2,30 MB)

8.
Real-time cutting tool condition monitoring in milling
Franc Čuš, Uroš Župerl, 2011, izvirni znanstveni članek

Opis: Reliable tool wear monitoring system is one of the important aspects for achieving a self-adjusting manufacturing system. The original contribution of the research is the developed monitoring system that can detect tool breakage in real time by using a combination of neural decision system and ANFIS tool wear estimator. The principal presumption was that force signals contain the most useful information for determining the tool condition. Therefore, the ANFIS method is used to extract the features of tool states from cutting force signals. ANFIS method seeks to provide a linguistic model for the estimation of tool wear from the knowledge embedded in the artificial neural network. The ANFIS method uses the relationship between flank wear and the resultant cutting force to estimate tool wear. A series of experiments were conducted to determine the relationship between flank wear and cutting force as well as cutting parameters. Speed, feed, depth of cutting, time and cuttingforces were used as input parameters and flank wear width and tool state were output parameters. The forces were measured using a piezoelectric dynamometer and data acquisition system. Simultaneously flank wear at the cutting edge was monitored by using a tool maker's microscope. The experimental force and wear data were utilized to train the developed simulation environment based on ANFIS modelling. The artificial neural network, was also used to discriminate different malfunction states from measured signals. By developed tool monitoring system (TCM) the machining process can be on-line monitored and stopped for tool change based on a pre-set tool-wear limit. The fundamental limitation of research was to develop a single sensor monitoring system, reliable as commercially available system, but 80% cheaper than multisensor approach.
Ključne besede: end-milling, tool condition monitoring, wear estimation, ANFIS
Objavljeno v DKUM: 10.07.2015; Ogledov: 1724; Prenosov: 121
URL Povezava na celotno besedilo

9.
Simple stochastic model for planning the inventory of spare components subject to wear-out
Alenka Brezavšček, 2011, izvirni znanstveni članek

Opis: We treat an industrial system which comprises of a number of identical components subject to wear-out. To support the system maintenance an appropriate inventory of spare components is needed. In order to plan the sufficient inventory of spare components, two variants of a simple stochastic model are developed. In both variants, the aim is to determine how many spare components are needed at the beginning of a planning interval to meet demand for corrective replacements during this interval. Under the first variant the acceptable probability of spare shortage during the planning interval is chosen as a decision variable. While in the second variant the adequate spare inventory level is assessed by taking into account the expected number of component failures within the planning interval. A comparison of both variants of the model shows that calculations involved in the second variant are simpler. However, it can only be used when the inventory of spare components can be planned for a relatively long period of time. The determination of an adequate number of spare components according to both variants of our model depends on the form of the probability density function of component failure times. Since the components are subject to wear-out, this function exhibits a peak-shaped form that can be described by different statistical density functions. Advantages and disadvantages of using the normal, lognormal, Weibull, and Gamma density function in our model are discussed. Among the probability density functions studied, the normal density function is found to be the most appropriate for calculations in our model. The applicability of both variants of the model is given through numerical examples using field data on electric locomotives of Slovenian Railways.
Ključne besede: industrial system, wear-out, maintenance, corrective replacements, spare components
Objavljeno v DKUM: 10.07.2015; Ogledov: 1555; Prenosov: 372
.pdf Celotno besedilo (2,38 MB)
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10.
Wear resistance of coke-crushing hammers
Franc Zupanič, 2013, izvirni znanstveni članek

Opis: This work investigated several methods for improving the wear resistance of the 42CrMo4 tool steel used for coke-crushing hammers. The methods embraced heat treatment for obtaining different combinations of strength and ductility of the bulk steel, and surface-engineering processes comprising TiN thin-film deposition using magnetron-sputtering, nitriding and WC/Ni weld deposit surfaced by gas metal arc (GMA) method. The wear-resistance was tested under industrial conditions. Oil quenching and tempering significantly increased the wear resistance in comparison to the as-received condition. Conversely, nitriding and TiN-hard coating did not show any significant improvement. WC/Ni weld deposit provided the best protection against wear, which was caused predominantly by hard abrasive particles present in the coke.
Ključne besede: zvarni spoj, mikrostrukture, obrabna odpornost, toplotna obdelava, obraba, kladivo, weld deposition, microstructure, impact coke crusher, heat treatment, wear, hammer
Objavljeno v DKUM: 10.07.2015; Ogledov: 1882; Prenosov: 72
URL Povezava na celotno besedilo

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