Strip snap analytics in cold rolling process using machine learning

Strip snap, also known as strip breakage or belt tearing, is an undesirable quality incident which results in yield loss and reduced work speed in the cold rolling process of strip products. Therefore, it is necessary to reveal a functional relationship between certain selected variables and strip snap event for the aim of quality improvement. In this study, the probability of strip snap occurrence was quantified by a selected measured variable. Several machine learning algorithms were adopted to predict this target probability. To validate this approach, a case study was conducted based on real-world data collected from an electrical steel reversing mill. The excessively good performance indicates several variables which are strongly correlated with the target

Molecular responses of mouse macrophages to copper and copper oxide nanoparticles inferred from proteomic analyses

The molecular responses of macrophages to copper-based nanoparticles have been investigated via a combination of proteomic and biochemical approaches, using the RAW264.7 cell line as a model. Both metallic copper and copper oxide nanoparticles have been tested, with copper ion and zirconium oxide nanoparticles used as controls. Proteomic analysis highlighted changes in proteins implicated in oxidative stress responses (superoxide dismutases and peroxiredoxins), glutathione biosynthesis, the actomyosin cytoskeleton, and mitochondrial proteins (especially oxidative phosphorylation complex subunits). Validation studies employing functional analyses showed that the increases in glutathione biosynthesis and in mitochondrial complexes observed in the proteomic screen were critical to cell survival upon stress with copper-based nanoparticles; pharmacological inhibition of these two pathways enhanced cell vulnerability to copper-based nanoparticles, but not to copper ions. Furthermore, functional analyses using primary macrophages derived from bone marrow showed a decrease in reduced glutathione levels, a decrease in the mitochondrial transmembrane potential, and inhibition of phagocytosis and of lipopolysaccharide-induced nitric oxide production. However, only a fraction of these effects could be obtained with copper ions. In conclusion, this study showed that macrophage functions are significantly altered by copper-based nanoparticles. Also highlighted are the cellular pathways modulated by cells for survival and the exemplified cross-toxicities that can occur between copper-based nanoparticles and pharmacological agents

POINTWISE LINEAR QUADRATIC OPTIMAL CONTROL OF A TANDEM COLD ROLLING MILL

ABSTRACTPOINTWISE LINEAR QUADRATIC OPTIMAL CONTROL OF ATANDEM COLD ROLLING MILLJohn R. Pittner, PhDUniversity of Pittsburgh, 2006The tandem cold rolling of metal strip is a complex multivariable process whose control presents a significant engineering challenge. The present technology generally relies on a control structure wherein the interactive coupling between process variables is partially reduced by several single-input-single-output and single-input-multi-output control loops operating on certain variables to decompose the overall problem into several separate problems to attempt to allow independent adjustment of strip tension and thickness anywhere in the mill. However, while the existing systems generally have been successful in producing an acceptable product, their failure to completely counteract the effects of interactions between process variables has limited their capability for improvement in performance and in robustness to disturbances and uncertainties. Various techniques for improvement have been proposed and some have been implemented. Many of these techniques offer some improvements, but also have shortcomings. Therefore there is a need for a better approach. It is considered that the pointwise linear quadratic optimal control might fulfill this need. This dissertation investigates the theoretical and applied aspects of this technique for control of a tandem cold rolling mill using criteria based on practical applications. A mathematical model of the mill is developed from which nonlinear state space equations are derived. Using these equations, a pointwise linear quadratic optimal controller is developed, and its performance for variations in operating speed and product are confirmed by simulation. Robustness to disturbances and uncertainties is also confirmed by simulation. The results are compared with those using typical industry practice

Developments in Directed Energy Deposition Additive Manufacturing: In-situ Hot Forging and Indirect Cooling

Additive Manufacturing (AM) by Directed Energy Deposition-arc (DED-arc) is competing with other AM technologies due to its high deposition rate, ability to produce large parts with medium/high geometric complexity and low capital and running costs. However, residual stresses, coarse microstructures, and defects on parts, such as cracks and pores, may compromise in-service industrial applications and need to be overcome. This work aimed to develop and validate two innovative process variants: one based on in-situ hot forging; and the other on temperature control, that is, indirect cooling of deposited material and hot forging. The hot forging variant consisted of locally forging the deposited layer at high temperatures using low forces. The goal is to create an uniform plastic deformation zone along the layer, to promote grain refinement, reduce material anisotropy and collapse defects. The variant based on temperature control consisted of cooling the hammer components and the shielding gas used to protect the molten pool, to increase the solidification rate and thus, prevent grain coalescence. For this, dedicated DED-arc equipment was designed and manufactured with specific features for research. The effect of hot forging was analysed in detail on 316LSi stainless steel, and the feasibility of its application was verified in other relevant industrial materials. It was concluded that hot forging can induce dynamic recrystallization, increase nucleation sites and prevent epitaxial grain growth. Thus, it contributes to an overall refined and homogeneous microstructure with improved mechanical properties. The developed cooling system lowered the average temperature of the nozzle and hammer during consecutive depositions. Cooling of the shielding gas had no major effect on the cooling rates and microstructure of the materials, however, it was observed that the hot forging changes the heat flow conditions of the part, promoting higher cooling rates.A tecnologia de deposição direta de energia por arco (DED-arc) tem competido com outras tecnologias de fabrico aditivo devido à sua elevada taxa de deposição, capacidade de produzir componentes de grandes dimensões com média/alta complexidade geométrica e baixos custos de implementação e funcionamento. Contudo, as elevadas tensões residuais, as microestruturas grosseiras, ou os defeitos do tipo poros, podem comprometer algumas aplicações industriais e necessitam de ser superados. Este trabalho visou desenvolver e validar duas variantes inovadoras de processo DED- arc: uma baseada no forjamento a quente; e outra no controlo de temperatura. A variante baseada no forjamento, consistiu em forjar o material depositado imediatamente após a deposição, utilizando baixas forças. O objetivo foi a produção de uma zona de deformação plástica uniforme ao longo de cada camada, para promover alterações microestruturais, nomeadamente o refinamento dos grãos e a redução da anisotropia. A variante baseada no trabalho termodinâmico consistiu em arrefecer os componentes do martelo e o gás utilizado para proteger o banho de fusão, com o objetivo de aumentar a taxa de arrefecimento e assim evitar a coalescência dos grãos. Neste sentido, foi concebido e fabricado um equipamento de DED-arc, com características específicas para investigação. O efeito do forjamento a quente foi estudado detalhadamente no aço inoxidável 316LSi, e foi verificada a viabilidade da sua aplicação noutros materiais relevantes industrialmente. Concluiu-se que o forjamento induz recristalização dinâmica, aumenta os pontos de nucleação e impede o crescimento de grãos epitaxiais, contribuindo para uma microestrutura globalmente mais fina, homogénea e com melhores propriedades mecânicas. O sistema de arrefecimento desenvolvido baixou a temperatura do bocal e do martelo durante as deposições consecutivas. O arrefecimento do gás de proteção não teve efeito nas taxas de arrefecimento nem na microestrutura do material, contudo, observou-se que o forjamento altera as condições de fluxo de calor, promovendo taxas de arrefecimento maiores

Aeronautical engineering: A special bibliography with indexes, supplement 82, April 1977

This bibliography lists 311 reports, articles, and other documents introduced into the NASA scientific and technical information system in March 1977

. Разработка цифровых алгоритмов управления приводами мехатронной системы реверсивной кле-ти толстолистового прокатного стана

Expanding the plate mill product range implies the improvement of control algorithms for the mechatronics control system drives of the reversing stands. The most important objectives include increasing the accuracy of geometric dimensioning and tolerancing, as well as improving the profile and surface flatness of rolled pro­ducts. The structure explaining the automatic ROLL-GAP CONTROL concept is provided, which allows controlling the thickness and gap between SMS-Demag AG rolls. This concept is implemented in the '5000' mill stand of Magnitogorsk Iron and Steel Works. The structural diagram of the automatic gauge control system (AGS) is presented. The functional diagram of the hydraulic gap control (HGC) system is presented, which includes a fast proportional control channel and a relatively slow integral position control channel. The principle of automatic thickness control is discussed, implemented in the automatic gauge control (AGC) system of the mill stand TCS controller. The diagram and dependences are prepared for the calculation of the nonlinear thickness controller parameters. The functions of the RAC regulator are described, intended for compensation of the tensile difference (gap spacing) at the mill stand sides. The dynamic impact compensation system functions are considered. The removal of the roll bending and deformation control signals is substantiated. The disadvantages of AGC are noted for sheets with a thickness below 10 mm. The most dangerous case is the tearing of metal fragments from the rear sheet side caused by the incorrect operation of the gauge control system. A method for hydraulic gap control is proposed based on the fast increase of the roll gap in the rear part of the rolled sheet during the last passage when rolling thin sheets. The results of experimental studies made on the '5000' mill are presented. The efficiency of the proposed control method has been confirmed. The oscillograms of signals are presented characterizing thickness variations. HGC and AGC systems with the proposed adjustments are proven to provide high-accuracy hydraulic position control and thickness control along the sheet length and width.При расширении сортамента продукции толстолистовых прокатных станов приобретает актуальность проблема совершенствования алгоритмов управления приводами мехатронной системы реверсивной клети. Важнейшими задачами являются повышение точности геометрических размеров, а также улучшение профиля и планшетности проката. Представлена структура, поясняющая концепцию ROLL-GAP CONTROLL автоматического регулирования толщины и зазора валков фирмы SMS-Demag AG. Данная концепция реализована на стане 5000 Магнитогорского металлургического комбината. Приведена структурная схема системы расчета и автоматического регулирования толщины (САРТ). Рассмотрена функциональная схема системы регулирования положения гидравлических нажимных устройств Hydraulic Gap Control (HGC), включающая быстродействующий канал пропорционального регулирования и относительно медленный канал интегрального регулирования положения. Рассмотрен принцип автоматического регулирования толщины, реализованный в ресурсе системы Automatic Gap Control (AGC) контроллера TCS клети. Представлены схема и зависимости для вычисления коэффициентов нелинейного регулятора толщины. Отмечены функции RAC-регулятора, предназначенного для компенсации разницы растяжений (перекоса) зазора по сторонам клети. Рассмотрены функции системы динамической компенсации возмущающих воздействий. Обосновано исключение сигналов коррекции противоизгиба и деформации валков. Отмечены недостатки САРТ при прокатке листов толщиной менее 10 мм. Наболее опасным является отрыв фрагментов металла от хвостовой части, вызванный некорректной работой системы задания толщины. Предложен способ управления гидравлическими нажимными устройствами, суть которого заключается в быстродействующем увеличении межвалкового зазора на «хвосте» раската в последнем проходе при прокатке тонких листов. Представлены результаты экспериментальных исследований, выполненных на стане 5000. Подтверждена техническая эффективность внедрения предложенного способа управления. Рассмотрены осциллограммы сигналов, характеризующих разнотолщинность. Доказано, что при предложенных настройках систем HGC и AGC обеспечивается высокая точность регулирования положения нажимных устройств и толщины по длине и ширине листа