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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Development of an actuation system for a specialized fixture: providing two degrees of freedom for single point incremental forming

Fatima, Mariam 01 February 2013 (has links)
In this thesis, an actuation system is developed for a Two-Axis Gyroscopic (TAG) adapter. This adapter is a fixture with two auxiliary axes which is used for the Single Point Incremental Forming (SPIF) technique to enhance a three-axis mill to have five-axis capabilities. With five-axis mill capabilities, variable angles between line segments of the toolpath and the tool can be obtained. To achieve specialized angles between a line segment and the SPIF tool, the sheet is rotated. Inverse kinematic equations for the TAG adapter are derived to calculate the required rotations for the TAG adapter’s auxiliary axes for a line segment of a toolpath. If the next line segment requires a different orientation of the sheet, the sheet is rotated while the tool follows the rotation of the sheet to maintain its position at the connecting point of the line segments of the toolpath. Five equations of motions are derived to calculate the three translations of the mill and two rotations of the TAG adapter’s frames, during forming. A toolpath execution algorithm is implemented in MATLAB which uses the five equations of motion to execute a toolpath. The algorithm generates an array of data points that can be used by a Computer Numerically Controlled (CNC) machine to follow a desired path. A visual representation for the execution of the toolapth is implemented in MATLAB and is used to illustrate the successful completion of a toolpath. A computer controlled motor system is selected and tested in this thesis which will ultimately be integrated with a worm gear system and a CNC machine to develop a full CNC actuation system. / UOIT
2

A STUDY OF ENERGY, CARBON DIOXIDE EMISSIONS AND ECONOMICS IN MACHINING: MILLING AND SINGLE POINT INCREMENTAL FORMING

BRANKER, KADRA 05 December 2011 (has links)
A simple model that includes energy and carbon dioxide (CO2) emissions in the economics of machining is proposed, which has been published in the highly respected and cited journal, Annals of CIRP (International Academy for Production Engineering). This is a timely analysis in current government discussions on a proposed carbon tax or a carbon cap and trade regime and greater energy efficiency. The new cost model is based on life cycle analysis methodology for the initial part production. An illustrative example is given showing that the cheapest electrical grid should not be chosen, if it also has the highest CO2 emissions. Accurate pricing is important, because the more expensive product was highly dependent on the carbon price. A comprehensive review of machining economic models is covered. However, there is a dearth of actual machining data in the literature. This work includes studies in milling and single point incremental forming (SPIF) which can be used by other manufacturing engineers in their machining economic model development. The first milling study involved simple straight cuts. In general, as feed rate (FD) increased (increasing the material removal rate, MRR), the energy consumed decreased as process time decreased. In contrast, as spindle speed (N) increased, energy consumed increased, since more power is drawn by the motor, without a process time reduction. Given the inverse power relationship observed for the time, energy, process CO2 and cost against MRR, the recommended parameters were the same at the highest FD and lowest N permissible. In the second milling study with constant N for a more complex part (sprocket), similar relationships were observed. However, for sprockets made at constant chip load (allowing FD and N to change together), there were varying prescribed MRRs for time, energy, process CO2 and cost minimization. The SPIF studies showed a similar relationship to the constant N milling, and, that results for a simple part can be extrapolated to improve efficiency in more complex parts. Finally, although the energy and carbon costs represented a small contribution to the final cost, their significance increased for higher efficiency parameters or user conditions, e.g. low labour rate. / Thesis (Master, Mechanical and Materials Engineering) -- Queen's University, 2011-12-03 19:58:07.76
3

Aplikace CNC programovaní na jednobodové tváření / CNC Programming if the Single Point Incremental Forming

Ladecký, Tomáš January 2010 (has links)
V současné době se zvyšuje potřeba rozvoje agilních výrobních postupů, které lze snadno přizpůsobit neustálému zavádění nových produktů na trh. Jednobodové inkrementální tváření je nový, inovativní a proveditelný tvářecí proces s jednoduchým uspořádáním. Proces se provádí při pokojové teplotě (tváření za studena) a vyžaduje CNC stroj, nástroj s kulovou hlavou a jednoduché příslušenství pro uchycení obrobku plechu. V samotném procesu jde o přírůstkové formování, řízené CNC programem. Plastická deformace je lokalizována pod formovacím nástrojem takže plech je tvářen souhrnem pohybů lokální plastické zóny. Tento proces je zdlouhavý a proto se hodí pouze pro prototypovou výrobu nebo pro malé výrobní dávky. Na druhé straně umožňuje vyšší tvářitelnost ve srovnání s konvenčními procesy tváření, umožňuje použití levných nástrojů a také je charakterizován krátkou dobou od návrhu po výrobu produktu. Tato práce je výsledkem mezinárodní spolupráce Danmarks Tekniske Universitet v Lyngby a Instituto Superior Técnico v Lisabonu. Práce začíná krátkým hodnocením dílčích tvářecích procesů, pokračuje představováním jednobodového inkrementálního tváření a identifikací jeho praktických aplikací. Teoretická část obsahuje přehled nového rámce pro jednobodové inkrementální tváření, který je vytvořen na základě analýzy styku třecích sil. Praktická část projektu poskytuje úplný popis experimentálních technik použitých pro charakterizaci materiálů a stanovení limitů tvářitelnosti, dále se analyzuje vliv různých vstupních parametrů procesu (poloměru nástroje, tepelné zpracování materiálu obrobku, druh maziva,...). Tato část také obsahuje přehled experimentálního uspořádaní procesu jednobodového inkrementálního tváření i krátký popis CAD / CAM vývoje tří testovacích modelů. Poté jsou popsány v samostatné kapitole výsledky pozorování a analýzy hlavních parametrů procesů, které ovlivňují tvařitelnostní limity v jednobodovém inkrementálním tváření v souvislosti s aplikovaným teoretickým rámcem. Výsledky experimentů z časti objasňují probíhající mezinárodní diskusi kolem tvářitelnosti mechanismu jednobodového inkrementálního tváření vzhledem k tradičním metodám tváření. Jako logické pokračování prováděných experimentů, byla práce rozšířena na více-stupňové jednobodové inkrementální tváření, které umožňuje tváření součástek (kalíšku) se svislými stěnami ve více krocích. Za účelem objasnění procesů spojených s tímhle procesem byly navrženy a ve čtyřech krocích vyrobeny dva experimentální modely. Hlavním přínosem této práce k více-stupňovému jednobodovému inkrementálnímu tváření byla úspěšná výroba součásti s nekruhovým průřezem a kolmými stěnami. S cílem aplikovat celkové znalosti získáných v předchozích částí práce byla vyrobena prototypová součást. Popis designu a vývoje prototypu je součástí práce. V neposlední řadě jsou celkové závěry uvedené v poslední kapitole. Předpokládá se, že tato práce přizpívá k lepšímu pochopení mechanismu jednobodového inkrementálního tváření.
4

Estampagem incremental de múltiplos passes em chapa de latão C268

Maximiliano, Gerson January 2016 (has links)
O presente trabalho investiga o comportamento da chapa de latão C268, com 0,50 mm de espessura, quando exposto ao processo de Estampagem Incremental de Chapas de Metal (Incremental Sheet Metal Forming -ISMF). Especificamente para a pesquisa, foram utilizadas as modalidades de Estampagem Incremental com Ponto Simples (Single Point Incremental Forming- SPIF) e Estampagem Incremental de Múltiplos Passes (Multi Pass Single Point Incremental Forming- MSPIF). Os experimentos foram baseados em uma geometria de tronco de pirâmide de base quadrada com 100 mm de lado e 45 mm de profundidade. Para as estratégias de estampagem foi atribuído, a estampagem helicoidal. Como resultado principal, foi verificado o ângulo de parede máximo atingido por cada processo de estampagem incremental. Adicionalmente, ensaios de tração, análise de deformações e de rugosidade da chapa de latão foram realizados. Todos os seus resultados estão detalhados na investigação. Para os parâmetros adotados nestes experimentos, o ângulo de parede obtido por SPIF foi maior do que pelo estudo proposto por MSPIF. / The present study investigates the performance of the brass plate C-268 with 0.50 mm thickness, when exposed to Incremental Sheet Metal Forming (ISMF). Specifically for research, it was used the modalities Single Point Incremental Forming (SPIF) and Multi Pass Single Point Incremental Forming (MSPIF). The experiments were based on a truncated pyramid geometry with square base 100 mm side and 45 mm depth. For forming strategies has been assigned, the helical forming. As the main outcome, it was found the maximum wall angle achieved by each process of incremental printing. In addition, tensile tests, analysis of deformation and roughness of the brass sheet were performed. All results are detailed in the investigation. For the parameters used in these experiments, the wall angle obtained by SPIF is greater than the study proposed by MSPIF.
5

Estampagem incremental de múltiplos passes em chapa de latão C268

Maximiliano, Gerson January 2016 (has links)
O presente trabalho investiga o comportamento da chapa de latão C268, com 0,50 mm de espessura, quando exposto ao processo de Estampagem Incremental de Chapas de Metal (Incremental Sheet Metal Forming -ISMF). Especificamente para a pesquisa, foram utilizadas as modalidades de Estampagem Incremental com Ponto Simples (Single Point Incremental Forming- SPIF) e Estampagem Incremental de Múltiplos Passes (Multi Pass Single Point Incremental Forming- MSPIF). Os experimentos foram baseados em uma geometria de tronco de pirâmide de base quadrada com 100 mm de lado e 45 mm de profundidade. Para as estratégias de estampagem foi atribuído, a estampagem helicoidal. Como resultado principal, foi verificado o ângulo de parede máximo atingido por cada processo de estampagem incremental. Adicionalmente, ensaios de tração, análise de deformações e de rugosidade da chapa de latão foram realizados. Todos os seus resultados estão detalhados na investigação. Para os parâmetros adotados nestes experimentos, o ângulo de parede obtido por SPIF foi maior do que pelo estudo proposto por MSPIF. / The present study investigates the performance of the brass plate C-268 with 0.50 mm thickness, when exposed to Incremental Sheet Metal Forming (ISMF). Specifically for research, it was used the modalities Single Point Incremental Forming (SPIF) and Multi Pass Single Point Incremental Forming (MSPIF). The experiments were based on a truncated pyramid geometry with square base 100 mm side and 45 mm depth. For forming strategies has been assigned, the helical forming. As the main outcome, it was found the maximum wall angle achieved by each process of incremental printing. In addition, tensile tests, analysis of deformation and roughness of the brass sheet were performed. All results are detailed in the investigation. For the parameters used in these experiments, the wall angle obtained by SPIF is greater than the study proposed by MSPIF.
6

Estampagem incremental de múltiplos passes em chapa de latão C268

Maximiliano, Gerson January 2016 (has links)
O presente trabalho investiga o comportamento da chapa de latão C268, com 0,50 mm de espessura, quando exposto ao processo de Estampagem Incremental de Chapas de Metal (Incremental Sheet Metal Forming -ISMF). Especificamente para a pesquisa, foram utilizadas as modalidades de Estampagem Incremental com Ponto Simples (Single Point Incremental Forming- SPIF) e Estampagem Incremental de Múltiplos Passes (Multi Pass Single Point Incremental Forming- MSPIF). Os experimentos foram baseados em uma geometria de tronco de pirâmide de base quadrada com 100 mm de lado e 45 mm de profundidade. Para as estratégias de estampagem foi atribuído, a estampagem helicoidal. Como resultado principal, foi verificado o ângulo de parede máximo atingido por cada processo de estampagem incremental. Adicionalmente, ensaios de tração, análise de deformações e de rugosidade da chapa de latão foram realizados. Todos os seus resultados estão detalhados na investigação. Para os parâmetros adotados nestes experimentos, o ângulo de parede obtido por SPIF foi maior do que pelo estudo proposto por MSPIF. / The present study investigates the performance of the brass plate C-268 with 0.50 mm thickness, when exposed to Incremental Sheet Metal Forming (ISMF). Specifically for research, it was used the modalities Single Point Incremental Forming (SPIF) and Multi Pass Single Point Incremental Forming (MSPIF). The experiments were based on a truncated pyramid geometry with square base 100 mm side and 45 mm depth. For forming strategies has been assigned, the helical forming. As the main outcome, it was found the maximum wall angle achieved by each process of incremental printing. In addition, tensile tests, analysis of deformation and roughness of the brass sheet were performed. All results are detailed in the investigation. For the parameters used in these experiments, the wall angle obtained by SPIF is greater than the study proposed by MSPIF.
7

Induction Assisted Single Point Incremental Forming of Advanced High Strength Steels

Al-Obaidi, Amar Baker Salim 28 September 2018 (has links)
Induction Assisted Single Point Incremental Forming (IASPIF) is a die-less hot sheet metal forming. The IASPIF does not apply characteristic complex tooling like those applied in deep drawing and bending. In this thesis, induction heating was used to heat up the sheet while simultaneously forming with a tool. The research goal is to improve the formability of high strength steels by heating. The IASPIF consists of non-complicated set up that allows induction heating to be utilized through the coil inductor moved under the sheet and synchronized with the forming tool that moves on the upper side of the sheet. The advanced high strength steel alloys, DP980, DP600 and 22MnB5 steels, were investigated. The influence of induction heating on formability was evaluated by the maximum wall angle that can be achieved in a single pass. Additionally, tool diameter and tool feed rate was also varied. The most influencing parameters were tool feed rate, induction power, and the profile depth. A new forming strategy was also developed by control the heating temperature through coupling the formed profile depth with a successively increased tool feed rate. The forming forces of DP980 steel sheet, were reduced from 7 kN to 2.5 kN when forming process was performed at room and elevated temperature, respectively. Stretching stresses were developed during forming process causing a high reduction in the resulting wall part thickness. New findings in this investigation were the reverse relationship between the step-down depth and the thickness reduction percentage. The smaller the tool diameter, the better was the formability. The finite element simulation of the investigated forming process showed that the increase in heating temperature has a direct effect on rising the plastic strain from 0.2 at room temperature to 1.02 at 800 ◦ C. The maximum true strain achieved in the resulting wall part thickness was determined by FEM simulations and validated with experimental trials. The part shape accuracy was measured and the highest deflection was founded when the part was formed by the highest step-down depth. Moreover, the minimum deflection in the part shape was achieved by utilizing a high induction power in the experiments. Finally, the resulting mechanical properties of the 22MnB5 alloy sheet material were tailored during IASPIF. For this purpose, the sheets were locally heated by induction during the forming process and subsequently quenched at different rates. As a result, the produced tailored parts consist of three different regions, which consist of a ductile, transitional and hardened region. The proposed procedure allows forming and quenching at the same time without transfer and thus, process time was reduced. / Die induktionsgestützte, inkrementelle Blechumformung (englisch: Induction Assisted Single-Point Incremental Forming IASPIF) ist Warmumformprozess, bei dem keine komplexen Werkzeuge wie beim Tiefziehen und Biegen benötigt werden. Inhalt dieser Arbeit ist die inkrementelle Umformung eines Bleches mit gleichzeitig ablaufender induktiver Erwärmung. Das Forschungsziel bestand in der Verbesserung der Umformbarkeit von hochfesten Stahlwerkstoffen wie DP600, DP980 und 22MnB5 durch eine gezielte partielle Erwärmung. Der prinzipielle Aufbau des Versuchsstandes besteht aus einem Spuleninduktor, der unterhalb des umzuformenden Blechs platziert ist, und der synchron mit dem Werkzeug – einem Drückdorn – während des Umformvorganges verfährt. Ein wesentlicher Untersuchungsschwerpunkt bestand in der Ermittlung der Einflussgrößen auf den untersuchten IASPIF-Prozess. Für die Bewertung der Umformbarkeit wurden hierbei der maximal erreichbare Teilwandwinkel und die Profiltiefe, die in einem Umformdurchgang herstellbar waren, ermittelt und ausgewertet. Darüber hinaus konnten im Rahmen der Arbeit die Induktionsleistung des Generators, der Werkzeugdurchmesser und die Werkzeugvorschubgeschwindigkeit als relevante Prozessparameter identifiziert werden. Im Ergebnis der durchgeführten Untersuchungen zeigten die Werkzeugvorschubgeschwindigkeit und die Induktionsleistung einen wesentlichen Einfluss auf die erreichbare Profiltiefe. Aufbauend auf den erzielten Ergebnissen konnte eine prozessangepasste Umformstrategie entwickelt werden, bei der eine konstante Erwärmungstemperatur durch das Koppeln der momentanen Profiltiefe mit einer sukzessiv steigenden Werkzeugvorschubgeschwindigkeit erreicht wird. Weiterhin ließen sich die Kräfte bei der Umformung eines Stahlbleches aus DP980 von 7 kN (bei Raumtemperatur) auf 2,5 kN (bei erhöhter Temperatur) reduzieren. Aufgrund des mit einem Streckziehvorgang vergleichbaren Spannungszustandes während des Umformprozesses war eine starke Verringerung der resultierenden Wanddicke zu beobachten. Als neue Erkenntnis in dieser Untersuchung konnte die umgekehrte Beziehung zwischen der Zustelltiefe und dem Dickenreduktionsprozentsatz abgleitet werden. Aus der Finite - Elemente - Simulation des vorgestellten Umformprozesses wurde erkennbar, dass die Erhöhung der Erwärmungstemperatur einen direkten Einfluss auf die plastische Dehnung von 0,2 (bei Raumtemperatur) auf 1,02 (bei 800 °C) hat. Mittels der numerischen Simulation und der nachfolgenden experimentellen Validierung erfolgte darüber hinaus die Bestimmung der maximalen wahren Dehnung, die in der resultierenden Wanddicke erreicht wurde. Bei den Versuchen mit der größten Zustellung ließ sich durch die Bestimmung der Teileformgenauigkeit die höchste Abweichung von der Sollgeometrie CAD Modell feststellen. Abschließend wurde nachgewiesen, dass der IASPIF Prozess auch zur Einstellung maßgeschneiderter Bauteileigenschaften wie der resultierenden mechanischen Eigenschaften des Blechmaterials aus 22MnB5 einsetzbar ist. Zu diesem Zweck wurden die Bleche während des Umformprozesses lokal induktiv erwärmt und anschließend zur Einstellung des gewünschten Gefüges bei unterschiedlichen Abkühlgeschwindigkeiten abgeschreckt.

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