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Los procesos de conformado incremental simétricos tales como trefilado, laminación cilíndrica, laminación cónica, repulsado, encolado, forjado rotatorio, conformado por flujo de llantas, etc.,tienen una amplia gama de aplicaciones en industrias tales como: automotriz, aeroespacial, ventilación, iluminación, tuberías de petróleo y gas, proceso de materiales a granel, productos químicos y médicos, etc. La mayoría de estos procesos se rigen por un enfoque de prueba y error y es necesario trabajadores altamente calificados. Como intento de superar esto y tener un mejor conocimiento del proceso introduciendo asimismo criterios científico surge este trabajo. Este proyecto se centra en la “laminación cónica incremental” del acero DC-04, un acero muy utilizado por su alta ductilidad. Para ello se ha utilizado una máquina de laminación incremental a escala de laboratorio. Los objetivos específicos han sido: a) determinar loslímites de conformado basado en el ángulo de ataque del rodillo (RAA por sus siglas en inglés), b) correlacionar la deformación plástica con la dureza de piezas producidas con éxito y c) diseñar e imprimir en 3D un prototipo para medir tensiones residuales de muestras laminadas. Para determinar los límites de conformado se ejecutaron varias pruebas de laminación cónica y se construyeron mapas de procesamiento a partir de ellas. Se han identificado zonas de formación seguras que conducen a una combinación óptima de parámetros: ángulo del mandril y velocidad de avance, que dan como resultado piezas laminadas con éxito. Además, se encontró que las zonas de formación seguras son óptimas cuando se implementa un RAA perpendicular a la superficie de los mandriles. Por otro lado, para correlacionar la deformación plástica con la dureza, se realizaron ensayos de tracción y medición de microdureza y se obtuvo una relación lineal, descrita por: 𝐻���𝑉��� = 63.5 𝜀���𝑒���𝑓���𝑓��� + 135.4. Finalmente, los prototipos para medir tensiones residuales fueron diseñados en SolidWorks e impresos por la impresora “Ender 3”. Después de varias pruebas, se obtuvieron con éxito tres prototipos para las muestras laminadas con mandriles de 15 °, 13 ° y 11 °. Els processos de conformat incremental simètrics com ara trefilat, laminació cilíndrica, laminació cónica, repusatge, retallada, encolat, forjat rotatori, conformat per flux de llantes, etc., tenen una àmplia gamma d'aplicacions en indústries com ara: automotriu, aeroespacial, ventilació, il·luminació, canonades de petroli i gas, procés de materials a granel, productes químics i mediqes, etc. La majoria d'aquests processos es regeixen per un enfocament de prova i error i és necessari treballadors altament qualificats. Com a intent de superar això i tenir un millor coneixement del procés incloent-hi criterir científics es que s’ha plantejat aquest treball. Aquest projecte se centra en la “laminació cònica incremental” de l'acer DC-04, un acer molt utilitzat per la seva alta ductilitat. Per a això s'ha utilitzat una màquina de laminació incremental a escala de laboratori. Els objectius específics han estat: a) determinar els límits de conformat basat en l'angle d'atac de la rulina (RAA per les seves sigles en anglès), b) correlacionar la deformació plàstica amb la duresa de peces produïdes amb èxit i c) dissenyar i imprimir en 3D un prototip per a mesurar tensions residuals de mostres laminades. Per a determinar els límits de conformat es van executar diverses proves de laminació cònica i es van construir mapes de processament a partir d'elles. S'han identificat zones de formació segures que condueixen a una combinació òptima de paràmetres: angle del mandril i velocitat d'avanç, que donen com a resultat peces laminades amb èxit. A més, es va trobar que les zones de formació segures són òptimes quan s'implementa un RAA perpendicular a la superfície dels mandrils. A més, per a correlacionar la deformació plàstica amb la duresa, es van realitzar assajos de tracció i mesurament de microduresa i es va obtenir una relació lineal, descrita per: 𝐻��𝑉�� = 63.5 𝜀��𝑒��𝑓��𝑓�� + 135.4. Finalment, els prototips per a mesurar tensions residuals van ser dissenyats en SolidWorks i impresos per la impressora “Ender 3”. Després de diverses proves, es van obtenir amb èxit tres prototips per a les mostres laminades amb mandrils de 15 °, 13 ° i 11 °. Rotational incremental forming processes such as spinning, flow forming, shear spinning, trimming, necking-in, rotatory forging, wheel rim flow forming, pulley forming, etc, have a wide range of applications in industries such as: Automotive, aerospace, ventilation, light & building, pipe oil & gas, bulk materials process, chemical & medical, etc. Most of these processes are ruled by a trial-and-error approach and by highly skilled workers. This project was designed as an attempt to overcome this and to have a better understanding of the process with a more scientific criteria. This project focuses on “Shear spinning processing” of steel DC 04, a steel widely used due to its high ductility. For this purpose, a spinning flow machine scaled at laboratory has been used. The specific goals have been: To determine the forming limit in shear spinning based on the roller attack angle (RAA), to correlate the plastic deformation with the hardness of successfully produced parts and to design and 3D print a prototype to measure residual stresses on conical laminated samples. To determine the forming limits several shear spinning tests were carried out and processing maps were constructed out of them. Safe forming zones have been identified leading to an optimal combination of parameters: mandrel angle and feed rate, that results in successfully processed parts. Additionally, it was found that the safe forming zones exhibit the best performance when a RAA perpendicular to the mandrels surface is implemented. Furthermore, to correlate the plastic deformation with hardness, tensile test and microhardness measurement were carried out and a linear trend was obtained, described as 𝐻�𝑉� = 63.5 𝜀�𝑒�𝑓�𝑓� + 135.4. Finally, the prototypes to measure residual stresses were designed in SolidWorks and printed by a printer “Ender 3”. After several trials, three prototypes were successfully obtained for the laminated samples of mandrels of 15°, 13° and 11°.

Polymeric scaffolds comprising two size scales of microfibers and submicron fibers can better support three-dimensional (3D) cell growth in tissue engineering, making them an important class of healthcare material. However, a major manufacturing barrier hampers their translation into wider practical use: scalability. Traditional production of two-scale scaffolds by electrospinning is slow and costly. For day-to-day cell cultures, the scaffolds need to be affordable, made in high yield to drive down cost. Combining expertise from academia and industry from the United Kingdom and United States, this study uses a new series of high-yield, low-cost scaffolds made by shear spinning for tissue engineering. The scaffolds comprise interwoven submicron fibers and microfibers throughout as observed under scanning electron microscopy and demonstrate good capability to support cell culturing for tumor modeling. Three model human cancer cell lines (HEK293, A549 and MCF-7) with stable expression of GFP were cultured in the scaffolds and found to exhibit efficient cell attachment and sustained 3D growth and proliferation for 30 days. Cryosection and multiphoton fluorescence microscopy confirmed the formation of compact 3D cell clusters throughout the scaffolds. In addition, comparative growth curves of 2D and 3D cultures show significant cell-type-dependent differences. This work applies high-yield shear-spun scaffolds in mammalian tissue engineering and brings practical, affordable applications of multiscale scaffolds closer to reality. © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 35: e2750, 2019.

This paper presents the implementation of an external axis control system on a conventional CNC machine so that the machine can be actively controlled in response to sensors such as vision and force. The controller that runs on an external computer has direct access to the CNC controller for machine position sensing. The control signals to the machine are sent through purpose built circuitry via the machine's manual pulse generator (MPG) inputs. To demonstrate the accuracy and performance of the control system, it was used to visually track the profile of a mandrel used for shear spinning. The implemented system eliminates the parallax error and the need to use an accurate pixel resolution. The raw tracking data is processed by a curvature detection algorithm that detects linear and circular segments and segment transitions. The results show that the visual tracking system provides accurate tracking results that are well within the tolerances used in the industry.

Three commercial Al-Mg alloys containing 3 wt.% to 6 wt.% of Mg (AlMg3, AlMg4.5Mn and AlMg6Mn) were subjected to different forming processes: shear spinning and cold rolling. The effect of Mg content and reduction in thickness on the tensile properties and microstructure evolution of Al-Mg alloys were studied. Both optical (OM) and transmission electron microscopy (TEM) were used for the microstructure characterization. The results show that the addition of Mg in these alloys increases the yield strength (YS) and ultimate tensile strength (UTS) in both cold rolled and spun specimens. The strength of all Al-Mg alloys after shear spinning was lower compared to the strength after cold rolling for the same strain. This effect was attributed to the occurrence of dynamic recovery during shear spinning and confirmed by transmission electron microscopy. [Projekat Ministarstva nauke Republike Srbije, br. TR-34018]