Construction of gear box for roller conditioner for disc mowers

V magistrskem delu je predstavljen proces konstruiranja novega gumijastega gnetilnika za diskaste kosilnice. Opisani so način in namen uporabe gnetilnikov, njihove prednosti in slabosti. Prikazane so trenutne izvedbe gumijastih gnetilnikov z dvema valjema. Izvedena je raziskava trga na področju diskastih kosilnic. Ugotovljene so bile priložnosti za nove rešitve. Opisane so ideje za izboljšave oz. nove rešitve postavitve valjev. Predstavljeni in vrednoteni so koncepti za novo izvedbo gumijastega gnetilnika. Za izbrani koncept (trije valji, gnani z zobniškim gonilom) je opravljeno detajliranje in modeliranje komponent. Prikazan je potek moči od traktorja do grebena in gumijastega gnetilnika. Opisani so proces izračuna oz. določitve geometrije zobnikov (stožčastih in valjastih), preračun medosnih razdalj, dimenzij gredi, izbira ležajev in oblikovanje ohišja. Natančneje je opisana, detajlirana in vrednotena stožčasta zobniška dvojica po standardu SIST ISO 10300. Izvedeno je vrednotenje gredi v gonilu in prikazana celotna zasnova gonila. Cilj znotraj magistrskega dela je bil razviti novo gonilo, ki bo nato izdelano, testirano in v prihodnosti implementirano na kosilnicah z gumijastim gnetilnikom.This thesis describes the process of construction and development of the new roller conditioner for disc mowers. It describes the types and usage of conditioners for disc mowers. The current solutions of roller conditioners with two rollers are shown and described, the thesis also contains analysis of the market and shows new opportunities for upgrades. The ideas for better positioning of rollers are described. Furthermore, new concepts are described and rated. The chosen concept (with three rollers and a gear box) is detailed and models are created. The process of power path from the tractor to the mower is described. This thesis includes the calculation of geometry for spur and bevel gears, calculations of distances between axes, shafts dimensions, construction of housings and bearings. The complete calculation of bevel gears is conducted and described, according to standard SIST ISO 10300. The calculations of shafts and whole design of gear box are included. The goal of this thesis is to develop new gear box, which will be made, implemented and tested on the mowers with roller conditioners

Thermal simulation of water-cooled electric motor

Zaključna naloga obravnava termične simulacije, kjer je analiziran vodno-hlajen asinhroni elektromotor. Simulacije so opredeljene na podlagi specifikacij motorja in kupčevih zahtev. Namen naloge je raziskati ozadje in princip delovanja programske opreme za izdelavo numeričnih simulacij prevoda toplote. Cilj zaključne naloge je izvesti zanesljive in realne simulacije, ki bodo v pomoč kupcu ter podjetju, ki izdeluje motorje. V teoretičnem delu naloge je predstavljena splošna zgradba in vrste elektromotorjev. Predstavljene so tudi osnove in zakoni o prevodu in prestopu toplote. V delu metodologije raziskave je predstavljen model s pripadajočimi robnimi in začetnimi pogoji. Prikazane so obremenitve modela ter predstavljeni so materiali, iz katerih so izdelane komponente. Rezultati analiz prikazujejo porazdelitev polja temperatur znotraj elektromotorja. Ugotovljena je tudi učinkovitost hladilnega sistema.This thesis shows thermal simulations of a water-cooled brushless electric motor. The simulations are defined on the basis of engine specifications and customer requirements. The purpose of the thesis is to explore the principle of the software, that we use for performing heat conduction numerical simulation. The goal of the work is to create reliable and realistic simulations, which will then be available to the customer and to the company, that makes motors. The theoretical part of the paper presents the general structure and types of electric motors. The basics and the laws of heat transfer are also presented. In the part of the research methodology, a numerical model with corresponding boundary and initial conditions is presented. The loads of the model are shown and the materials from which the components are made are also presented. The results of the analysis show the distribution of the temperature field within the electric motor and the efficiency of the cooling system

Stabilisation of butter with rosemary antioxidants

The aim of the present study was to test the antioxidant activity of rosemary extract and its mixture with propylene glycol on the stability of fat in butter. Rosemary extract was added at a concentration of 0.02% (w/w) and mixture of rosemary extract with propylene glycol at a concentration of 0.25% (w/w) to the cream before churning. For comparison, control samples without added antioxidant were also prepared and tested. Samples were stored at 4 °C and at 20 °C for 27 days and their peroxide values were determined periodically. The measurement of peroxide values for butter at 60 and 98 °C was also performed. Activity of rosemary extracts was compared with synthetic antioxidant BHT. The rosemary extract and its mixture with propylene glycol exhibited strong antioxidant activity in butter when added to a cream before churning and in an aqueous emulsion system of β-carotene and linolenic acid

Isolation and concentration of natural antioxidants with high-pressure extraction

In present work, the purification of crude rosemary extract with supercritical fluids is presented. Carbon dioxide was used as a solvent. The crude extract was prepared from rosemary with conventional extraction process. The supercritical CO2 extraction of crude extracts was performed at pressures 10 and 20 MPa and temperatures 35 and 60 °C. The best results were obtained at pressure 10 MPa and temperature 35 °C. The content of carnosic acid in the samples before and after high pressure extraction was identified by high performance liquid chromatography. The content of carnosic acid in purified extract is higher compared to crude extract. The antioxidative efficiency of extracts was determined by measuring peroxide value. Activity ofpurified rosemary extracts is higher compared to crude extracts

Phenols, proanthocyanidins, flavones and flavonols in some plant materials and their antioxidant activities

Methanol extracts prepared from five plant materials native to the Mediterranean area, namely olive tree (Olea europaea) leaf, St. John\u27s wort (Hypericum perforatum), hawthorn (Crataegus laevigata), oregano (Origanum vulgare) and laurel leaf (Lauris nobilis), were examined for their phenolic components. Total phenolic content was determined by the Folin-Ciocalteu method. The content of proanthocyanidins in acid-hydrolysed extracts was determined spectrophotometrically. The contents of free flavones (apigenin andluteolin) and flavonols (kaempferol, myricetin and quercetin) were determined by HPLC analysis. The time of hydrolysis of flavones, flavonols andproanthocyanidins was optimised. Antioxidant activities of apigenin, luteolin, kaempferol, myricetin, quercetin and of plant extracts were examined. Antioxidative activities were studied in sunflower oil at 98 °C, by measuring peroxide value, and in an aqueous emulsion system of -carotene and linoleic acid by measuring the absorbance of the sample. Among flavones and flavonols investigated, only myricetin inhibited oxidation of sunflower oil. All other flavones and flavonols showed pro-oxidative activity. Oppositely, in the emulsion system, only apigenin showed pro-oxidative activity while otherflavones and flavonols and plant extracts inhibited oxidation of -carotene

Pretreatment of Natural Materials Used for Supercritical Fluid Extraction of Commercial Phytopharmaceuticals

A proper method was to be developed for the pretreatment of different types of natural materials in order to increase the efficiency of supercritical fluid extraction (SFE) regarding yield and active substance content. The effects of different mechanical pretreatments were investigated: flaking, impact plus shearing, and cutting plus grinding. Additionally, the influence of intermediate rapid gas decompression was studied. Significant effects of the applied pretreatments on the yield (increase by up to 1350 %) were shown for SFE of selected oilseeds, artemisia aerial parts, and the lichen Usnea barbata. Flaking was the most effective pretreatment for increasing the yield of SFE of fennel seeds, artemisia aerial parts, and Usnea lichen, while impact plus shearing was optimal for processing amaranth, milk thistle, and oat seeds. The use of defined optimal pretreatments led to notable increases in the contents of usnic acid (50 %) and artemisinin (300 %)