Jauhinterien valmistuksen kehittäminen

Diplomityö käsittelee eräälle paperiteollisuuden komponentteja valmistavalle yritykselle tehtyä tutkimusta, jossa tutkittiin erilaisia valmistusmenetelmiä, joilla voidaan valmistaa uudenlaisia jauhinteriä. Diplomityössä ideoitiin erilaisia jauhinteränkonstruktiovaihtoehtoja. Vaihtoehtoja havainnollistamaan piirrettiin jokaisesta ratkaisusta 3D- mallit. Vaihtoehtojen pohjalta päätettiin suoritettavat valmistustestaukset. Työssä suoritettiin valmistustestejä kuitulaserilla, hiilidioksidilaserilla sekä hienosädeplasmalla. Näiden testien perusteella saatiin näkemys siitä, mikä konstruktiovaihto on valmistusteknisesti paras, täyttäen samalla jauhinterälle asetetut vaatimukset. Diplomityön tuloksena syntyi toimiva ja kustannustehokas ratkaisu jauhinterien valmistamiseksi.

Koneinvestoinnin suunnittelu valmistavaan teollisuuteen

Tämän diplomityön tavoitteena oli tutustua ohutlevyjen nykyaikaisiin koneellisiin leikkausmenetelmiin ja tutkia niiden soveltuvuutta yrityksen tarpeisiin. Kohdeyrityksessä investoinnin tarve jakautui tuottavuusinvestoinnin, korvausinvestoinnin ja strategisen investoinnin kesken. Tavoitteena oli luoda investointipolku, jonka avulla poissuljettiin menetelmät, jotka eivät soveltuneet yrityksen tuotantoon. Työn kirjallisuusosuudessa tarkastellaan teoriatietoja, jotka liittyvät yleisesti nykyaikaisiin ohutlevyjen leikkausmenetelmiin sekä investointiprojektin suunnitteluun ja toteutuksen teoriaan. Lisäksi käsitellään investointeihin liittyviä kannattavuus- ja kustannuslaskennan perusperiaatteita. Työn empiirisessä osassa selvitettiin yrityksen ohutlevyosien valmistuksen periaatteita nykytila-analyysin avulla. Tämän perusteella määritettiin nykyaikaisista markkinoilla olevista menetelmistä yritykselle soveltuvin. Tutkimuksen perusteella laserleikkaus oli menetelmistä soveltuvin. Perusinvestoinniltaan laser oli vaihtoehtoisista menetelmistä kallein, mutta se soveltui käytettävyyden, tehokkuuden, joustavuuden ja muiden ominaisuuksiensa perusteella parhaiten tuotannon tarpeisiin. Työn merkittävimmät tulokset osoittivat, että investoinnin kannattavuus riippui koneelle saatavasta käyttösuhteesta. Uusien koneiden tehokkuus lyhentäisi tuotannon läpimenoaikoja, mutta ilman riittävää kapasiteetin käyttöastetta kappaleiden omakustannusarvo nousisi. Lopputulokset ja suositukset on esitetty työn lopussa.

Design and application of experimental methods for steel sheet shearing

Shearing is the process where sheet metal is mechanically cut between two tools. Various shearing technologies are commonly used in the sheet metal industry, for example, in cut to length lines, slitting lines, end cropping etc. Shearing has speed and cost advantages over competing cutting methods like laser and plasma cutting, but involves large forces on the equipment and large strains in the sheet material. The constant development of sheet metals toward higher strength and formability leads to increased forces on the shearing equipment and tools. Shearing of new sheet materials imply new suitable shearing parameters. Investigations of the shearing parameters through live tests in the production are expensive and separate experiments are time consuming and requires specialized equipment. Studies involving a large number of parameters and coupled effects are therefore preferably performed by finite element based simulations. Accurate experimental data is still a prerequisite to validate such simulations. There is, however, a shortage of accurate experimental data to validate such simulations. In industrial shearing processes, measured forces are always larger than the actual forces acting on the sheet, due to friction losses. Shearing also generates a force that attempts to separate the two tools with changed shearing conditions through increased clearance between the tools as result. Tool clearance is also the most common shearing parameter to adjust, depending on material grade and sheet thickness, to moderate the required force and to control the final sheared edge geometry. In this work, an experimental procedure that provides a stable tool clearance together with accurate measurements of tool forces and tool displacements, was designed, built and evaluated. Important shearing parameters and demands on the experimental set-up were identified in a sensitivity analysis performed with finite element simulations under the assumption of plane strain. With respect to large tool clearance stability and accurate force measurements, a symmetric experiment with two simultaneous shears and internal balancing of forces attempting to separate the tools was constructed. Steel sheets of different strength levels were sheared using the above mentioned experimental set-up, with various tool clearances, sheet clamping and rake angles. Results showed that tool penetration before fracture decreased with increased material strength. When one side of the sheet was left unclamped and free to move, the required shearing force decreased but instead the force attempting to separate the two tools increased. Further, the maximum shearing force decreased and the rollover increased with increased tool clearance. Digital image correlation was applied to measure strains on the sheet surface. The obtained strain fields, together with a material model, were used to compute the stress state in the sheet. A comparison, up to crack initiation, of these experimental results with corresponding results from finite element simulations in three dimensions and at a plane strain approximation showed that effective strains on the surface are representative also for the bulk material. A simple model was successfully applied to calculate the tool forces in shearing with angled tools from forces measured with parallel tools. These results suggest that, with respect to tool forces, a plane strain approximation is valid also at angled tools, at least for small rake angles. In general terms, this study provide a stable symmetric experimental set-up with internal balancing of lateral forces, for accurate measurements of tool forces, tool displacements, and sheet deformations, to study the effects of important shearing parameters. The results give further insight to the strain and stress conditions at crack initiation during shearing, and can also be used to validate models of the shearing process.

Cutting edge: IL-1α is a crucial danger signal triggering acute myocardial inflammation during myocardial infarction.

Myocardial infarction (MI) induces a sterile inflammatory response that contributes to adverse cardiac remodeling. The initiating mechanisms of this response remain incompletely defined. We found that necrotic cardiomyocytes released a heat-labile proinflammatory signal activating MAPKs and NF-κB in cardiac fibroblasts, with secondary production of cytokines. This response was abolished in Myd88(-/-) fibroblasts but was unaffected in nlrp3-deficient fibroblasts. Despite MyD88 dependency, the response was TLR independent, as explored in TLR reporter cells, pointing to a contribution of the IL-1 pathway. Indeed, necrotic cardiomyocytes released IL-1α, but not IL-1β, and the immune activation of cardiac fibroblasts was abrogated by an IL-1R antagonist and an IL-1α-blocking Ab. Moreover, immune responses triggered by necrotic Il1a(-/-) cardiomyocytes were markedly reduced. In vivo, mice exposed to MI released IL-1α in the plasma, and postischemic inflammation was attenuated in Il1a(-/-) mice. Thus, our findings identify IL-1α as a crucial early danger signal triggering post-MI inflammation.

Avaliação do desempenho do aço D6 tratado termicamente e netretado em plasma com gaiola catódica visando aplicação industrial

In this research there was an evaluation of the best conditions of nitriding in plasma within a cathodic cage at an atmosphere of 80% N2-20%H2 in samples of tool manganese steel AISI D6, cold working, treated thermally in the following conditions: tension relief, treated thermally to temperature of maximum heat, temperate heat and temperate and temperate heat. A pressure of 2.5mbar and temperatures of 400 and 300ºC com treatment time of two and three hours were used to evaluate its performance as cutting tool (punch) of bicycle backs. Hardness, micro-structural aspects (layer thickness, interface, grain size etc), and crystal phases on the surface were appraised. When treated to tension relief, thermally treated to maximum heat temperature, temperature and temperate heat, the samples presented hardness levels of 243HV, 231HV, 832HV, and 653HV, respectively. The best nitrification conditions were: four hours and 300ºC for heat samples. A superficial hardness of 1000HV and a 108µm thickness for the nitrided layer were found in these samples

Filmes orgânicos contendo óxido de alumínio depositados a plasma

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Efeito da implantação iônica por imersão em plasma no aço ferramenta tipo H13

Pós-graduação em Engenharia Mecânica - FEG

Sintering and model of thermal residual stress for getting cutting tools from functionally gradient materials

Cutting tools with higher wear resistance are those manufactured by powder metallurgy process, which combines the development of materials and design properties, features of shape-making technology and sintering. The annual global market of cutting tools consumes about US$ 12 billion; therefore, any research to improve tool designs and machining process techniques adds value or reduces costs. The aim is to describe the Spark Plasma Sintering (SPS) of cutting tools in functionally gradient materials, to show this structure design suitability through thermal residual stress model and, lastly, to present two kinds of inserts. For this, three cutting tool materials were used (Al2O3-ZrO2, Al2O3-TiC and WC-Co). The samples were sintered by SPS at 1300 °C and 70 MPa. The results showed that mechanical and thermal displacements may be separated during thermal treatment for analysis. Besides, the absence of cracks indicated coherence between experimental results and the residual stresses predicted.

Design and optimization of components and processes for plasma sources in advanced material treatments

The research activities described in the present thesis have been oriented to the design and development of components and technological processes aimed at optimizing the performance of plasma sources in advanced in material treatments. Consumables components for high definition plasma arc cutting (PAC) torches were studied and developed. Experimental activities have in particular focussed on the modifications of the emissive insert with respect to the standard electrode configuration, which comprises a press fit hafnium insert in a copper body holder, to improve its durability. Based on a deep analysis of both the scientific and patent literature, different solutions were proposed and tested. First, the behaviour of Hf cathodes when operating at high current levels (250A) in oxidizing atmosphere has been experimentally investigated optimizing, with respect to expected service life, the initial shape of the electrode emissive surface. Moreover, the microstructural modifications of the Hf insert in PAC electrodes were experimentally investigated during first cycles, in order to understand those phenomena occurring on and under the Hf emissive surface and involved in the electrode erosion process. Thereafter, the research activity focussed on producing, characterizing and testing prototypes of composite inserts, combining powders of a high thermal conductibility (Cu, Ag) and high thermionic emissivity (Hf, Zr) materials The complexity of the thermal plasma torch environment required and integrated approach also involving physical modelling. Accordingly, a detailed line-by-line method was developed to compute the net emission coefficient of Ar plasmas at temperatures ranging from 3000 K to 25000 K and pressure ranging from 50 kPa to 200 kPa, for optically thin and partially autoabsorbed plasmas. Finally, prototypal electrodes were studied and realized for a newly developed plasma source, based on the plasma needle concept and devoted to the generation of atmospheric pressure non-thermal plasmas for biomedical applications.

Modelling, diagnostics and experimental analysis of plasma assisted processes for material treatment

This work presents results from experimental investigations of several different atmospheric pressure plasmas applications, such as Metal Inert Gas (MIG) welding and Plasma Arc Cutting (PAC) and Welding (PAW) sources, as well as Inductively Coupled Plasma (ICP) torches. The main diagnostic tool that has been used is High Speed Imaging (HSI), often assisted by Schlieren imaging to analyse non-visible phenomena. Furthermore, starting from thermo-fluid-dynamic models developed by the University of Bologna group, such plasma processes have been studied also with new advanced models, focusing for instance on the interaction between a melting metal wire and a plasma, or considering non-equilibrium phenomena for diagnostics of plasma arcs. Additionally, the experimental diagnostic tools that have been developed for industrial thermal plasmas have been used also for the characterization of innovative low temperature atmospheric pressure non equilibrium plasmas, such as dielectric barrier discharges (DBD) and Plasma Jets. These sources are controlled by few kV voltage pulses with pulse rise time of few nanoseconds to avoid the formation of a plasma arc, with interesting applications in surface functionalization of thermosensitive materials. In order to investigate also bio-medical applications of thermal plasma, a self-developed quenching device has been connected to an ICP torch. Such device has allowed inactivation of several kinds of bacteria spread on petri dishes, by keeping the substrate temperature lower than 40 degrees, which is a strict requirement in order to allow the treatment of living tissues.

Avaliação do desempenho do aço D6 tratado termicamente e netretado em plasma com gaiola catódica visando aplicação industrial

In this research there was an evaluation of the best conditions of nitriding in plasma within a cathodic cage at an atmosphere of 80% N2-20%H2 in samples of tool manganese steel AISI D6, cold working, treated thermally in the following conditions: tension relief, treated thermally to temperature of maximum heat, temperate heat and temperate and temperate heat. A pressure of 2.5mbar and temperatures of 400 and 300ºC com treatment time of two and three hours were used to evaluate its performance as cutting tool (punch) of bicycle backs. Hardness, micro-structural aspects (layer thickness, interface, grain size etc), and crystal phases on the surface were appraised. When treated to tension relief, thermally treated to maximum heat temperature, temperature and temperate heat, the samples presented hardness levels of 243HV, 231HV, 832HV, and 653HV, respectively. The best nitrification conditions were: four hours and 300ºC for heat samples. A superficial hardness of 1000HV and a 108µm thickness for the nitrided layer were found in these samples

Testosterone Therapy Differently Regulates The Anti- And Pro-inflammatory Cytokines In The Plasma And Prostate Of Rats Submitted To Chronic Ethanol Consumption (uchb).

Ethanol consumption damages the prostate, and testosterone is known by anti-inflammatory role. The cytokines were investigated in the plasma and ventral prostate of UChB rats submitted or not to testosterone therapy by ELISA and Western blot, respectively. Additionally, inflammatory foci and mast cells were identified in the ventral prostate slides stained by hematoxylin and eosin and toluidine blue, respectively. Inflammatory foci were found in the ethanol-treated animals and absent after testosterone therapy. Plasma levels of IL-6 and IL-10 were not changed while TNFα and TFG-β1 were increased in the animals submitted testosterone therapy. Regarding to ventral prostate, IL-6 did not alter, while IL-10, TNFα, and TFG-β1 were increased after testosterone therapy. Ethanol increases NFR2 in addition to high number of intact and degranulated mast cell which were reduced after testosterone therapy. So, ethanol and testosterone differentially modulates the cytokines in the plasma and prostate.

Propylthiouracil Quantification In Human Plasma By High-performance Liquid Chromatography Coupled With Electrospray Tandem Mass Spectrometry: Application In A Bioequivalence Study.

A rapid, sensitive and specific method for quantifying propylthiouracil in human plasma using methylthiouracil as the internal standard (IS) is described. The analyte and the IS were extracted from plasma by liquid-liquid extraction using an organic solvent (ethyl acetate). The extracts were analyzed by high performance liquid chromatography coupled with electrospray tandem mass spectrometry (HPLC-MS/MS) in negative mode (ES-). Chromatography was performed using a Phenomenex Gemini C18 5μm analytical column (4.6mm×150mm i.d.) and a mobile phase consisting of methanol/water/acetonitrile (40/40/20, v/v/v)+0.1% of formic acid. For propylthiouracil and I.S., the optimized parameters of the declustering potential, collision energy and collision exit potential were -60 (V), -26 (eV) and -5 (V), respectively. The method had a chromatographic run time of 2.5min and a linear calibration curve over the range 20-5000ng/mL. The limit of quantification was 20ng/mL. The stability tests indicated no significant degradation. This HPLC-MS/MS procedure was used to assess the bioequivalence of two propylthiouracil 100mg tablet formulations in healthy volunteers of both sexes in fasted and fed state. The geometric mean and 90% confidence interval CI of Test/Reference percent ratios were, without and with food, respectively: 109.28% (103.63-115.25%) and 115.60% (109.03-122.58%) for Cmax, 103.31% (100.74-105.96%) and 103.40% (101.03-105.84) for AUClast. This method offers advantages over those previously reported, in terms of both a simple liquid-liquid extraction without clean-up procedures, as well as a faster run time (2.5min). The LOQ of 20ng/mL is well suited for pharmacokinetic studies. The assay performance results indicate that the method is precise and accurate enough for the routine determination of the propylthiouracil in human plasma. The test formulation with and without food was bioequivalent to reference formulation. Food administration increased the Tmax and decreased the bioavailability (Cmax and AUC).

Reduced Plasma Angiotensin Ii Levels Are Reversed By Hydroxyurea Treatment In Mice With Sickle Cell Disease.

Sickle cell disease (SCD) pathogenesis leads to recurrent vaso-occlusive and hemolytic processes, causing numerous clinical complications including renal damage. As vasoconstrictive mechanisms may be enhanced in SCD, due to endothelial dysfunction and vasoactive protein production, we aimed to determine whether the expression of proteins of the renin-angiotensin system (RAS) may be altered in an animal model of SCD. Plasma angiotensin II (Ang II) was measured in C57BL/6 (WT) mice and mice with SCD by ELISA, while quantitative PCR was used to compare the expressions of the genes encoding the angiotensin-II-receptors 1 and 2 (AT1R and AT2R) and the angiotensin-converting enzymes (ACE1 and ACE2) in the kidneys, hearts, livers and brains of mice. The effects of hydroxyurea (HU; 50-75mg/kg/day, 4weeks) treatment on these parameters were also determined. Plasma Ang II was significantly diminished in SCD mice, compared with WT mice, in association with decreased AT1R and ACE1 expressions in SCD mice kidneys. Treatment of SCD mice with HU reduced leukocyte and platelet counts and increased plasma Ang II to levels similar to those of WT mice. HU also increased AT1R and ACE2 gene expression in the kidney and heart. Results indicate an imbalanced RAS in an SCD mouse model; HU therapy may be able to restore some RAS parameters in these mice. Further investigations regarding Ang II production and the RAS in human SCD may be warranted, as such changes may reflect or contribute to renal damage and alterations in blood pressure.