At voestalpine Precision Strip AB, the slitting process is used frequently. Slitting is a commonly applied manufacturing technique during sheet metal processing that aims to split large coils of sheet metal into narrower widths. The coiled sheets are uncoiled and transferred to a slitter, where they pass between rotating circular knives that produce long and straight cuts, splitting the wide sheet into desired widths. However, during operation, their slitting knives are occasionally damaged. This means that the knives must be replaced, which wastes both time and money.   The goal of this project is therefore to examine the damage of a degraded slitting knife. A scanning electron microscope (SEM) is used to analyse the fracture surface and the microstructure of the knife. Further analysis of the knife is a Vickers hardness test to determine the knife’s hardness. Moreover, finite element (FE) simulations of the slitting process are performed in FE software Abaqus to understand the stresses that the knives are subject to during operation. The results show that the Mises stress reaches a maximum value of around 2250 MPa, which is approximately 75% of the materials yield stress in compression.   The SEM images show clear signs of smooth cleavage zones in the fracture area, indicating that the knife has failed by a brittle fracture. Furthermore, the images reveal possible signs of fatigue. The hardness test proved that the knife is very hard with a hardness of 802,2 HV. Plenty of carbides were revealed by the microstructure test – mainly two types. MC vanadium carbides and M6C carbides mainly consisting of tungsten and molybdenum, which explains the hardness of the knife.   To draw further conclusions on the damage of slitting knives in the future, there needs to be proper documentation of the slitting process. This involves taking note of the knife setup, the sheet material and its thickness, as well as the lifetime of the knives as failure occurs.

The spin-splitting energies in strained bulk wurtzite aluminum nitride (AlN) are studied using the linear combination of atomic orbital method. It is found that strain and crystal field induce not only a linear-k (£\wz ) but also two cubic-k terms (£^¡¦and £f¡¦ ) in the two-band k¡Dp Hamiltonian Hso=(£\wz-£^¡¦k2//+£f¡¦k2z)(£mxky-£mykx)+H0so, where H0so=(-£^0k2//+£f0k2z)(£mxky-£mykx) is for ideal wurtzite and generates a cone-shaped minimum-spin-splitting (MSS) surface. As biaxial strain increases, the shape of the MSS surface changes from a hexagonal hyperboloid of two sheets in unstrained AlN to a hexagonal cone, and eventually becomes a hyperboloid of one sheet. The spin-splitting energies of first conduction band for A-plane and M-plane wurtzite are calculated by the sp3 linear combination of atomic orbital (LCAO). The results show the spin-splitting energies are dominated by linear-k term but contribution of cubic-k terms can not be neglected for larger k//. The parameter of linear-k and cubic-k terms are evaluated from the LCAO calculated spin-splitting energies fitting to two band k¡Ep model as increasing well width. The coefficients of linear-k and cubic-k terms decrease.

Die Verarbeitung von Folien auf Schneid und Wickelmaschinen erzeugt je nach verwendetem Material Schneidstaubpartikel, welche die Produktqualität herabsetzen können. Um eine hohe Qualität sicherzustellen, wird der Schneidstaub in unmittelbarer Nähe zu seiner Entstehung durch spezielle Absaugungsvorrichtungen entfernt. Versuche haben jedoch gezeigt, dass trotz hoher Absaugleistung bei bestimmten Prozessparametern ein Teil der Partikel nicht erfasst wird. Daher wird im Anschluss an eine Erhebung der bestehenden Systemgrößen ein Modell der Absaugdüse mittels numerischer Simulation auf ihre Eignung zur Partikelentfernung untersucht. Die Untersuchung zeigt, dass bei der Auslegung der Düse eine Berücksichtigung der auf der Folie entstehenden Grenzschicht zwingend erforderlich ist. Um eine zuverlässige Absaugung aller Schneidstaubpartikel auch bei extremen Prozesseinstellungen sicherzustellen, werden weitere Untersuchungen und Anpassungen erforderlich.

This thesis deals with the cutting of steel thin-walled parts by slitting saw. Its subject is to study and test of cutting edges of slitting saws with a goal to reduce cutting forces to a minimum. The thesis is divided into the theoretical and practical part. In the theoretical part, existing knowledge about slitting saws and general cutting technology is analyzed. In the practical part testing of four slitting saws with different geometries of cutting edges during machining of chosen thin-walled part is performed. The performed measurements show that by the proper choice of the geometry of cutting edge, the cutting force can be reduced approximately by 30 %.

The pulp- and paper industry is a key industry globally and stands for a production of 600 million tonnes pulp and paper worldwide with a total revenue of 400 billion dollars. Due to high quality requirements on paper, it is important to use instruments that control that the produced paper fulfill the promised requirements. To control the quality, a sample strip needs to be taken along the full length of each paper reel. The purpose of this master’s thesis project was consequently to develop a unit that will be used when cutting out these samples.  The project started with a pre-study on existing sample cutters to define all integrated subsystems and their functionalities, advantages and drawbacks. The essential subsystems were found to be: (1) paper reel cutting, (2) path movement, (3) motion generation and (4) mechanical transmission. The advantages and drawbacks were found by interviewing people who have used the cutters or in any way have encountered them for opinions, experience and knowledge. Sample winding is an additional subsystem which was found in a few of the existing cutters but was not further studied.  After defining were the problems and development potentials lay, a range of concepts were generated for the subsystems. These concepts were presented to a defined target group to ensure a unit which will create costumer value. By taking their views and ideas into account, further concept development was made. After a few iterations, one concept was chosen for each subsystem in an evaluation with domain experts.  A detail study and design were then made which incorporated all subsystems into one unit. The solution: (1) has two rotating circular blade pushed against sharp guide rails, (2) is hand-held with two pair of wheels on the cutter-head and a digital inclinometer, (3) has a manually generated motion and (4) uses a synchronous belt drive which transfer the manually generated motion to the rotating blades. In addition to this, complete 2D and 3D drawings, along with a bill of materials, were delivered for the future manufacturing of the unit.  Since this thesis presents no solution for the sample winding, the next step is to develop a collector which is easily handled and should be able to co-use the manually generated power with the rotating blades. Further, a design which allows modularization of the unit should be developed. / Pappersindustrin är en nyckelindustri globalt och står för en produktion på 600 miljoner ton pappersmassa och papper över hela världen med en total intäkt på 400 miljarder dollar. På grund av höga kvalitetskrav på papper är det viktigt att använda instrument som kontrollerar att det producerade papperet uppfyller de utlovade kraven. För att kontrollera kvaliteten måste en provremsa tas längs hela pappersrullen. Syftet med denna masteruppsats var följaktligen att utveckla en enhet som kommer att användas vid utskärning av dessa prover.  Projektet startades med en förstudie av befintliga provskärare för att definiera alla integrerade delsystem och deras funktioner, fördelar och nackdelar. De väsentliga delsystemen visade sig vara: (1) skärning av pappersrulle, (2) rörelse av vägar, (3) generering av rörelse och (4) mekanisk kraftöverföring. Fördelarna och nackdelarna hittades genom att intervjua personer som har använt skärarna eller på något sätt har stött på dem för åsikter, erfarenhet och kunskap. Upprullning av proverna är ett ytterligare delsystem som hittades i vissa befintliga skärare men studerades inte vidare.  Efter att ha definierat var problemen och utvecklingspotentialerna låg, genererades ett antal lösningar för delsystemen. Dessa koncept presenterades för en definierad målgrupp för att säkerställa en enhet som skapar kundvärde. Genom att ta hänsyn till deras åsikter och idéer, vidareutvecklades lösningarna. Efter några iterationer valdes ett koncept för varje delsystem i en utvärdering med domänexperter.  En detaljstudie och -design gjordes sedan som inkluderade alla delsystem i en enhet. Lösningen: (1) har två roterande cirkulära knivar tryckta mot vassa styrskenor, (2) är handhållen med två par hjul på skärhuvudet och en digital lutningsmätare, (3) har en manuellt genererad rörelse och (4) använder en synkroniserad remdrivning som överför den manuellt genererade rörelsen till de roterande bladen. Utöver detta levererades kompletta 2D- och 3D-ritningar tillsammans med en stycklista för den framtida tillverkningen av enheten.  Eftersom den här rapporten inte innehåller någon lösning för upprullning är nästa steg att utveckla en provupprullare som är lätt att hantera och bör kunna använda den manuellt genererade effekten. Vidare bör en design som möjliggör modulering av enheten utvecklas.

La prévision de la sédimentation d'une rivière requiert l'utilisation d'un modèle mathématique régissant l'écoulement et de données d'observation. Le but de ce travail est de proposer une méthode d'assimilation de données qui permet de reconstituer les champs en tenant en compte du modèle et des données d'observation. La méthode qui est proposée est fondée sur les techniques de contrôle optimal. On présente les problèmes de sédimentation et leurs approximations numériques, un algorithme de décomposition est introduit et sa convergence est étudiée. En préalable à l'exploitation à des problèmes réels, on a vérifié la faisabilité de la méthode variationnelle d'assimilation de données pour trois types de problèmes de transport des sédiments : 1) la détermination de la condition initiale, 2) l'identification des paramètres, 3) l'estimation de l'erreur de la modélisation. Les études de sédimentation sur le terrain conduisent à des problèmes numériques de très grande dimension, dans une dernière partie on s'est intéressé à des techniques permettant la réduction de l'espace de contrôle pour obtenir des problèmes d'une taille raisonnable.

Master‘s thesis deals with sawing of the thin-walled parts with high speed steel slitting saw. At first the most used conventional and unconventional possibilities of materiál cutting are described by a form of search. The next chapter describes forces arising from splitting saw machining, including their dependence on a specific cutting force, a chip cross section and a engagement angle. The second part of the thesis deals with the technological improvement of the cutting process, where three possible solutions are considered – geometry of the cutting tool, PVD coating deposition of the cutting tool and process fluid change. In the experimental part non coated slitting saw with burrs, non coated deburred slitting saw and coated slitting saws are compared. Used coatings were Ti(C,N), Cr-Al-Si-N, Al-Cr-B-N, and TripleCoating Cr, which is consisting of three layers TiN + (Al,Ti)N + Cr-Al-Si-N. The experiment has shown that the cutting forces inceases as the edge radius and wear level of the cutting tool increases. Coated cuttung tools has shown lower differences between the first and the last cut. Slitting saws have been also used in real cutting process to verify experimental results.

This thesis is dealing with the issue of residual stress present in the wall of a polymer pipe and the influence on its lifetime. Experimental data obtained by the ring slitting method are evaluated and the tangential residual stress in the wall of polypropylene pipe is determined. The evaluation is carried out using a new methodology based on the curved beam theory. The method is verified using numerical simulation. 3D numerical model is used to verify the behavior of the pipe, when there are both tangential and axial residual stresses present in the pipe wall, because the presence of axial stress causes a rise in the magnitude of tangential residual stress. A correction of the tangential stress values corresponding to the pipe length is then proposed. It is shown, that the distribution of the tangential residual stress does not depend significantly on the dimensions or ma-terial of the extruded pipe and a general equation is proposed to describe the distribution. This general distribution is then involved in the calculations of the pipe lifetime that are carried out using a method based on the linear elastic fracture mechanics. A significantly lower lifetimes are obtained when taking the residual stress into account.