Control-Oriented Characterization of Product Properties during Hot Hole-Flanging of X46Cr13 Sheet Material in a Progressive-Die

Robust and versatile production is enabled by a closed-loop control of product properties. This essentially relies on the characterization of the interaction between properties and available degrees of freedom to control the process. In particular, this work examines the setting of collar height, thinning, curvature, and hardness during hot hole-flanging of X46Cr13 sheet material with simultaneous heat treatment to identify approaches for a closed-loop property control in hot hole-flanging during multi-stage hot sheet metal forming. To scrutinize the adjustability of the hardness of X46Cr13 sheet material by heat treatment with rapid heating and short dwell times, quenching tests with austenitizing temperatures from 900 to 1100 °C and dwell times from 1 to 300 s were carried out. A hardness between 317 and 680 HV10 was measured. By analyzing the force-displacement curve and the contact situation between tools and blank during hot hole-flanging, an understanding for the process was established. To determine the adjustability of geometrical collar properties and the hardness of the collar, collars were formed at punch speeds between 5 and 100 mm/s and at different temperatures. Here, a dependency of the geometry of the collar on temperature and punch speed as well as setting of the hardness was demonstrated

Control-Oriented Characterization of Product Properties During Hot Hole-Flanging of X46Cr13 Sheet Material in a Progressive-Die

Robust and versatile production is enabled by a closed-loop control of product properties. This essentially relies on the characterization of the interaction between properties and available degrees of freedom to control the process. In particular, this work examines the setting of collar height, thinning, curvature, and hardness during hot hole-flanging of X46Cr13 sheet material with simultaneous heat treatment to identify approaches for a closed-loop property control in hot hole- flanging during multi-stage hot sheet metal forming. To scrutinize the adjustability of the hardness of X46Cr13 sheet material by heat treatment with rapid heating and short dwell times, quenching tests with austenitizing temperatures from 900 to 1100 ◦ C and dwell times from 1 to 300 s were carried out. A hardness between 317 and 680 HV10 was measured. By analyzing the force-displacement curve and the contact situation between tools and blank during hot hole-flanging, an understanding for the process was established. To determine the adjustability of geometrical collar properties and the hardness of the collar, collars were formed at punch speeds between 5 and 100 mm/s and at different temperatures. Here, a dependency of the geometry of the collar on temperature and punch speed as well as setting of the hardness was demonstrated

Reduction of Warping in Kinematic L-Profile Bending Using Local Heating

Kinematic bending of profiles allows to manufacture parts with high flexibility concerning the geometry. Still, the production of profiles with asymmetric cross-sections regarding the force application axis using kinematic bending processes offers challenges regarding springback and warping. These geometric deviations can be reduced by partial, cross-sectional heating during the process as it lowers the flow stress locally. In this work, the influence of partial, cross-sectional heating during a three-roll push-bending process on the warping and springback of L-profiles is investigated. Numerical and experimental methods reveal the influence of temperature on warping and springback. A newly developed analytical model predicts the warping and bending moment in the design phase and assists to understand the effect of warping reduction through partial heating during plastic bending. With increasing temperature of the heated profile area, the warping is reduced up to 76% and the springback of the bend profiles is decreased up to 44%. The warping reduction is attributed to a shift in stress free fiber due to the temperature gradient between heated and room temperature areas. The shift of stress-free fiber leads to an adapted shear center position, resulting in an approximated “quasi-symmetric” bending case

On mesh dependencies in finite-element-based damage prediction : application to sheet metal bending

The properties of a local and a regularised gradient-enhanced continuum damage model are highlighted and both types of models are applied to the simulation of an air bending process. Constitutive relations are summarised for both Lemaitre-type models and a brief description of their implementation into Abaqus user material subroutines is given. With (several) material parameters obtained from a basic parameter identification process, an air bending experiment is simulated with different mesh densities. By means of the damage evolution as well as the distribution of representative damage and hardening variables, the mesh dependence of the local model in contrast to the mesh independence of the gradient-enhanced model is analysed for two air bending processes with different die width

Informe científico de Beca de Entrenamiento: Bianchi, María Belén (2015-2016)

En este trabajo se tuvo como objetivo evaluar el uso del recubrimiento antimicrobiano comestible a base de dextrina, ácido cítrico y ácido ascorbico sobre la calidad y el tiempo de vida útil de morrones, tanto verde como rojos recien cosechados y de verdurleria, y de repollitos de bruselas recien cosechados. Se formuló el recubrimiento probando diferentes concentraciones de antioxidantes y del soporte polimérico. Se estudió la variación de propiedades fisicas (resistencia a la compresión, pérdida de peso, contenido de sólidos solubles), microbiológicas (recuento de hongos y levaduras, coliformes y aerobios mesófilos) y químicas (cuantificación de fenoles totales y malonildialdheído) a medida que transcurre el tiempo, hasta observar deterioro organoléptico. Se puso a punto la técnica de cuantificación de fenoles totales y de malondialdehido (MDA) adaptándola a las diferentes matrices vegetales de estudio (morrones verdes y rojos y repollitos de bruselas). Se pudo concluir que la aplicación del recubrimiento comestible en morrones recien cosechados permitió retardar el deterioro y conservar la calidad fisicoquímica. Con respecto a los morrones obtenidos de verdulería, el tratamiento fue efectivo solo en la conservación de calidad respecto a lo microbiológico. Por otra parte en los repollitos de bruselas el tratamiento también fue efectivo para los parámetros estudiados. En este último caso se sugiere ampliar la investigación. Las dificultades encontradas en el desarrollo de las actividades fueron el reemplazo de las hortalizas, debido a considerar la estacionalidad de las mismas para poder trabajar con hortalizas recién cosechadas. Para finalizar, se destaca el cumplimiento del objetivo de trabajo propuesto durante el desarrollo de la Beca de Entrenamiento, debido a que se evaluó el uso del recubrimiento antimicrobiano comestible sobre la calidad y el tiempo de vida útil de hortalizas, a través del estudio de la variación de propiedades fisicas, microbiológicas y químicas a medida que transcurre el tiempo de almacenamiento