Metso develops (among many other things) refiners. The refiner grinds the wood chips intopulp. The grinding is done by segments that are placed on a rotor inside the refiner hosing.In time this segments wear and needs to be replaced.When changing refiner segments or performing service to the refiner the rotor needs to berotated. To perform the rotating motion today the overhead crane is used. This procedure isboth impractical, dangerous and takes precious time from the overhead crane. Because ofthis Metso wanted to create a new way to rotate the rotor.The aim of this thesis is to create a tool or equipment which can be used to rotate therefiner rotor and can be installed as an upgrade on all Metso refiner models.The proposed design is driven with a 1.1 kW electrical motor and a gearbox with a gear ratioof approximately 1:217. The torque is transferred from the outgoing gearbox shaft to therefiner shaft with the help of gearwheels. To connect the gearbox gearwheel with the refinershaft gearwheel, the gear motor has to be moveable in a radial direction. This is done by themeans of two shafts that glides in four bushings. On the gearbox shaft a gearwheel with 120mm of face width is mounted. The large face width is used to take up the axial movement ofthe refiner shaft.The proposed concept fulfills all of the demands set in the pilot study. The design is goodbecause of the low cost and straight forward design that is easy to build and simple to use.The disadvantage is that the equipment is a bit large and heavy, but as stationary equipmentthis should not be a problem.

No description available.

Aluminium castings with a large grain structure have poor mechanical properties which are primarily due to casting defects as opposed to fine grain structure. The grain refinement practice using chemical addition is well established for wrought alloys, however in the case of casting alloys, the practice of adding grain refiners and the impact on castability is not well established. The addition of well known Al-5Ti-B grain refiner to casting alloys with silicon (Si) content above 3 wt.% is not effective. This is believed to be due to the chemical reaction between Ti and Si. The current research aim is to find an alternative, but effective, chemical phase which can refine Al-Si alloy grains. Based on a crystallographic database search and intermetallic phases found in Aluminium–Niobium-Boron, there exists several iso-structural phases similar to those of Al3Ti and TiB2. We have selected a phase which exhibits chemical phase stability with Si (below 900 oC) and developed a potential novel grain refiner Nb-B for Al-Si cast alloys. Various Al-Si binary alloys and a commercial sourced LM6 (Al-10Si-Mg) cast alloys were cast after novel grain refiner addition to the melt. It is the first time that such fine grain structures were achieved for Al-Si alloys when Si >4wt.%. It is believed that Nb-B grain refiner enhances the heterogeneous nuclei in the melt. The effectiveness of this grain refiner under various cooling rate conditions is investigated to simulate various practical casting conditions. Due to increased heterogeneous nuclei density, a fine grain structure is also obtained at low cooling rates and the grain size is less sensitive to the cooling rate. The processing of high Si containing alloys for complex shaped castings with reduced defects, fine grain structure and improved mechanical properties are now possible.

<p>Examensarbetet har utförts på Metso Refiner Segments AB i Hagfors, Värmland. Gjuteriet arbetar mot pappersindustrin och produkten de tillverkar kallas för malsegment. Malsegmenten sitter monterad på två stora skivor i en raffinör, vilket används för att framställa mekanisk pappersmassa. </p><p>För att minska personalkostnaderna och för att få bort ett monotont moment för operatörerna vill Metso automatisera den station där malsegmenten härdas. Värmebehandlingen sköts idag av två operatörer och är tänkt att efter en automatisering kunna skötas av en operatör. </p><p>Arbetet har gått ut på att ta fram förslag på automatisk utrustning som gör att härdstationen kan gå obemannad i en timme. Den största utmaningen har legat i att anpassa automationsutrustningen till det stora antalet storlekar. Metso tillverkar idag cirka 1400 olika varianter av malsegmenten. Detta försvårar arbetet med att konstruera en utrustning som kan klara av alla modeller och samtidigt vara ekonomiskt försvarbar samt driftsäker. </p><p>Två olika koncept på utrustningar presenteras i rapporten. Koncepten har genom en utvärdering med våra handledare blivit utvald bland totalt åtta förslag. Dessa två koncept är funktionsförslag på hur en automationsutrustning kan vara utformad. Om en investering ska göras krävs en närmare specificering av ingående detaljer. Under arbetet har en strävan efter att vara tydlig med funktion och utformning vilket är för att underlätta en vidare specificering.</p>

Examensarbetet har utförts på Metso Refiner Segments AB i Hagfors, Värmland. Gjuteriet arbetar mot pappersindustrin och produkten de tillverkar kallas för malsegment. Malsegmenten sitter monterad på två stora skivor i en raffinör, vilket används för att framställa mekanisk pappersmassa. För att minska personalkostnaderna och för att få bort ett monotont moment för operatörerna vill Metso automatisera den station där malsegmenten härdas. Värmebehandlingen sköts idag av två operatörer och är tänkt att efter en automatisering kunna skötas av en operatör. Arbetet har gått ut på att ta fram förslag på automatisk utrustning som gör att härdstationen kan gå obemannad i en timme. Den största utmaningen har legat i att anpassa automationsutrustningen till det stora antalet storlekar. Metso tillverkar idag cirka 1400 olika varianter av malsegmenten. Detta försvårar arbetet med att konstruera en utrustning som kan klara av alla modeller och samtidigt vara ekonomiskt försvarbar samt driftsäker. Två olika koncept på utrustningar presenteras i rapporten. Koncepten har genom en utvärdering med våra handledare blivit utvald bland totalt åtta förslag. Dessa två koncept är funktionsförslag på hur en automationsutrustning kan vara utformad. Om en investering ska göras krävs en närmare specificering av ingående detaljer. Under arbetet har en strävan efter att vara tydlig med funktion och utformning vilket är för att underlätta en vidare specificering.

Refiners are used in the pulp and paper industry to separate wood chips into individual fibres and to develop the morphology of fibres to be suitable for the type and grade of paper to be produced. Within a refiner are discs, at least one of which rotates at high speed and all of which are lined with radial patterns of bars on their opposing surfaces. As the chips and fibres are accelerated through the refiner, compressive and shear forces are applied to them by the bars as the opposed discs cross each other. Experiments have shown that the contact mechanics of bar-crossings are a significant factor in the development of fibre properties. To investigate the contact mechanics in operating refiners, a prototype piezoelectric-based sensor was developed to measure the forces applied by the bars. This work re-designs the prototype sensor to function at the mill-scale, and validates the design in two trials. Performance during these trials is presented along with an in-depth analysis of the recorded data. Arrays of force sensors were installed in two single-disc refiners: a pilot-scale machine operating as a primary stage, and a mill-scale machine operating as a rejects stage. In the rejects refiner, mean forces were highest at the periphery of the refining zone, while in the primary stage, mean forces were higher at the sensor closest to the refiner axis. Higher coefficients of friction were measured in the primary stage refiner, which also showed less active bar-crossings. Distributions of peak force values were generated for a range of standard operating conditions. Primary stage refining showed near decreasing exponential distributions, while rejects refining showed skewed normal distributions. These results indicate a fundamental difference in the behavior of these refiners, which is explained in terms of the processing stage of the wood fibre and scale of the refiner. Past laboratory experiments in a single-bar refiner have shown that pulp consistency can greatly affect the contact mechanics of bar-crossing impacts. The effect was observed as a positive correlation between the coefficient of friction and the mass fraction of fibre in the stock, known as the consistency. In the present work, a similar correlation was found in the primary stage refiner, but only in the sensor closest to the refiner axis. No significant changes in the coefficient of friction were observed in the rejects refiner; however, only a small range of consistencies was tested. These initial findings suggest relationships found in past laboratory tests may translate to larger-scale equipment. The clashing of plates during refining accelerates bar wear, and delays production. An investigation of the ability of the sensor to predict plate clash was conducted. The force sensors consistently provided advanced warning of a clash event, many seconds before the accelerometer-based plate protection system currently in use by the mill. A sensitivity study showed that the new system was able to outperform the accelerometer system over a range of detection settings, and that the accelerometer could not be tuned to match the performance of the new system.

Submitted by Maria Suzana Diniz (msuzanad@hotmail.com) on 2015-11-10T14:25:28Z No. of bitstreams: 1 arquivototal.pdf: 4860574 bytes, checksum: 7d8f4382d837797d850361eeced8c0c9 (MD5) / Made available in DSpace on 2015-11-10T14:25:28Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 4860574 bytes, checksum: 7d8f4382d837797d850361eeced8c0c9 (MD5) Previous issue date: 2014-11-21 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The process Squeeze casting is a casting process in which the cast metal is solidified in the liquid state under pressure into a metallic permanent mold closed by a puncture. It is an economical and relatively simple technique, possessing great potential for automation and high production rates. The product is of high quality and usually has the final form. Currently, components of aluminum alloys, copper, magnesium, cast iron, stainless steels and nickel-based superalloys are easily manufactured by squeeze casting, for our work alloy studied for this process was the Aluminum Alloy Zinc. The aim of this study was to analyze the influence of operating parameters such as pressure and pressing time on the correlation between solidification macrostructure and mechanical properties of dilute Al-Zn through the process Squeeze Casting, alloy alloys used in this work of Al-1% Zn ; Al-3% Zn and 5% Al-Zn, and pressures of 50, 100 and 150 MPa and solidification without pressure and with pressing time of 5 seconds. The results show the macrostructure, tensile test and hardness. The study of macro-structure and properties of these alloys shows the effectiveness of this process in the grain refining and improves the mechanical properties of the alloys studied. / O processo Squeeze Casting é um processo de fundição, no qual o metal vazado no estado liquido é solidificado sob pressão dentro de uma coquilha metálica fechada por um punção. É uma técnica econômica e relativamente simples, possuindo grande potencial para automatização e altas taxas de produção. O produto é de alta qualidade e geralmente, tem a forma final. Atualmente, componentes de ligas de alumínio, cobre, magnésio, ferro fundido, aços inoxidáveis e de superligas à base de níquel são facilmente fabricados por squeeze casting, para o nosso trabalho a liga estudada para esse processo foi a liga de Alumínio Zinco. O objetivo deste trabalho foi analisar a influência dos parâmetros operacionais como pressão e tempo de prensagem na correlação entre macroestrutura de solidificação e propriedades mecânicas de ligas diluídas de Al-Zn, através do processo Squeeze Casting, utilizou neste trabalho ligas de Al-1%Zn; Al-3%Zn e Al-5%Zn, além de pressões de 50, 100 e 150 MPa, bem como a solidificação sem pressão, com tempo de prensagem de 5 s. Os resultados obtidos mostram a macroestrutura, ensaio de tração e dureza. O estudo da macroestrutura e propriedades dessas ligas mostra a eficácia desse processo no refino de grão e melhora as propriedades mecânicas das ligas estudadas.

High shear mixing offers a promising solution for particle dispersion in a liquid with intensive turbulence and high shear rate, and has been widely used in the chemical, food and pharmaceutical industries. However, a practical high shear mixing process has not yet been adapted to solve the particle agglomeration in metallurgy due to the high service temperature and reactive environment of liquid metal. In this study, the effect of high shear mixing using the newly designed rotor-stator high shear device have been investigated with both Al and Mg matrix composites reinforced with SiC particles through casting. The microstructural observation of high shear treated Al and Mg composites show improved particle distribution uniformity in the as-cast state. Increased mechanical properties and reduced volume fraction of porosity are also obtained in the composite samples processed with high shear. With the melt conditioning procedure developed for twin roll casting process, two distinct solutions has been provided for thin gauge Mg strip casting with advanced microstructure and defect control. The melt conditioning treatment activates the MgO as heterogeneous nuclei of α-Mg through dispersion from continuous films to discrete particles. Thus enhanced heterogeneous nucleation in the twin roll casting process not only refines the α-Mg grain size but also eliminates the centre line segregation through equiaxed grain growth and localized solute distribution. The grain refinement of the α-Mg through SiC addition has also been studied through EBSD and crystallographic approaches. Two reproducible and distinct crystallographic orientation relationships between α-SiC (6H) and α-Mg have been determined: [1010]SiC//[2113]Mg, (0006)SiC//(1011)Mg, (1216)SiC//(2202)Mg and [0110]SiC//[1100]Mg, (0006)SiC// (0002)Mg, (2110)SiC//(1120)Mg.

En segmentbytesrigg kan ofta användas vid segmentbyte för raffinörer. Raffinörer har stora hållare som det sitter segment i för att mala ned träflis till pappersmassa. Eftersom dessa nöts ut med tiden är det viktigt att de byts ut, och där är segmentbytesriggen ett viktigt användarverktyg. På uppdrag av Valmet i Sundsvall undersöker detta kandidatarbete möjligheten att förenkla en av Valmets nuvarande segmentbytesriggar. Detta för att göra den mindre dyr och komplex, och därmed mer lättillverkad och mer kostnadseffektiv. Arbetet har följt designprocessens tillvägagångssätt, vilket har bestått av tre stycken faser; analytisk, kreativ och en presentationsfas. Detta resulterade slutligen i ett nytt koncept för en segmentbytesrigg, som är mer simplifierad, billigare att tillverka, men fortfarande bibehåller samma huvud- och bifunktioner. Konceptet har fått kompromissa med viss praktisk bekvämlighet för att kunna nå målet om att göra riggen mer kostnadseffektiv och lättillverkad. / Adjunkt

This thesis is focused on the novel wood chip refining process called AdvancedThermomechanical Pulp (ATMP) refining. ATMP consists of mechanical pretreatmentof chips in Impressafiner and Fiberizer prior to first stage refining atincreased intensity. Process chemicals (this study was concentrated on hydrogenperoxide and magnesium hydroxide) are introduced into the first stage refiner.It is known that the use of chemicals in TMP process and first stage refining atelevated intensity can reduce the energy demands of refining. The downside is thatthey also alter the character of the produced pulp. Reductions in fibre length andtear index are usually the consequences of refining at elevated intensity. Additionof chemicals usually leads to reduction of the light scattering coefficient. Usingstatistical methods it was shown that it is possible to maintain the TMP character ofthe pulp using the ATMP process. This is explained by a separation of thedefibration and the fibre development phases in refining. This separation allowsdefibration of chips to fibres and fibre bundles without addition of chemicals orincrease in refining intensity. Chemicals are applied in the fibre developmentphase only (first stage refiner). The energy demand in refining to reach tensileindex of 25 Nm/g was reduced by up to 1.1 MWh/odt (42 %) using the ATMPprocess on Loblolly pine. The energy demand in refining of White spruce, requiredto reach tensile index of 30 Nm/g, was reduced by 0.65 MWh/odt (37%).Characterizations of individual fibre properties, properties of sheets made fromlong fibre fractions and model fibre sheets with different fines fractions werecarried out. It was established that both the process equipment configuration (i.e.the mechanical pre‐treatment and the elevated refining intensity) and the additionof process chemicals in the ATMP process influence fibre properties such as external and internal fibrillation as well as the amount of split fibres. Improvementof these properties translated into improved properties of sheets, made from thelong fibre fractions of the studied pulps. The quality of the fines fraction alsoimproved. However, the mechanisms of improvement in the fines quality seem tobe different for fines, generated using improved process configuration andaddition of process chemicals. The first type of fines contributed to better bondingof model long fibre sheets through the densification of the structure. Fines whichhave been influenced by the addition of the process chemicals seemed in additionto improve bonding between long fibres by enhancing the specific bond strength.The improved fibre and fines properties also translated into better airpermeability and surface roughness of paper sheets, properties which areespecially important for supercalendered (SC) printing paper. The magnitude offibre roughening after moistening was mainly influenced by the processequipment configuration while the addition of process chemicals yielded lowestfinal surface roughness due to the lowest initial surface roughness. There was nodifference in how fines fractions from the studied processes influenced the fibreroughening. However, fines with better bonding yielded model fibre sheets withhigher PPS, probably due to their consolidation around fibre joints. Hence, thedecrease in PPS can probably be attributed to the improvements in the long fibrefraction properties while the improvement of fines quality contributed to thereduction of air permeability.The process chemicals, utilized in the ATMP process (Mg(OH)2 and H2O2) alsoproved to be an effective bleaching system. Comparable increases in brightnesscould be reached using the ATMP process and conventional tower bleaching.Maximum brightness of the pulp was reached after approximately 10 minutes ofhigh‐consistency storage after refining or 40 minutes of conventional bleaching.This study was conducted using a pilot scale refiner system operated as a batchprocess. Most of the experiments were performed using White spruce (Piceaglauca). In Paper I, Loblolly pine (Pinus taeda) was used. It is believed that theresults presented in this thesis are valid for other softwood raw materials as well,but this limitation should be considered.