Hector Plascencia Mora

Model of the Planetary Gear Based on Multi-Body Method and Its Comparison with Experiment on the Basis of Gear Meshing Frequency and Sidebands

Model tests can be used as a source of information about gearbox dynamics. Simulation of phenomena occurring in gearboxes allows to identify vibration signatures related to other failures of gears, bearings and shafts. In the chapter, the rigid-elastic model of the planetary gear is presented. The model was developed on the basis of the multi-body dynamics method. To conduct dynamic simulations specialized software MSC ADAMS was used. The multi-body method merges advantages of CAD modeling and efficient numerical simulations. Developed model allows to simulate the transmission error generated by a gearbox and forces in planet-sun and planet-ring meshing. In the tests it was observed that phase relations between meshing process influence on the sidebands of meshing frequency harmonics. The model was compared with experimental data on the basis of gears’ meshing frequencies and modulation sidebands.

EL PROCESO DE BRUÑIDO CON BOLA: ESTADO DEL ARTE DE UNA TECNOLOGÍA EN DESARROLLO

El brunido de bola es un proceso secundario de mejoramiento de las propiedades fisico-mecanicas y el acabado superficial de piezas manufacturadas. A pesar de ser conocido hace mas de 30 anos, recientemente se ha visto potencializado su uso industrial en diversas aplicaciones como la fabricacion de moldes para inyeccion de plastico, herramentales para el conformado de metales, asi como, numerosos componentes en la industria automotriz, ferrocarrilera, aeronautica y aeroespacial; por lo que su investigacion es fundamental. En las ultimas decadas diversas investigaciones se han enfocado en el estudio teorico, numerico y experimental del proceso de brunido de bola; con la finalidad de estudiar, predecir y analizar la influencia de parametros especificos que permitan mejorar la comprension del proceso asi como la optimizacion de los parametros involucrados en el. En este articulo, se presenta un analisis de diversos articulos cientificos, que son de gran relevancia para el proceso de brunido de bola. El estudio permite acelerar la comprension del proceso, presentando un estudio actualizado del estado del arte e identificando las diversas areas de oportunidad para mejorarlo.

OPTIMIZACIÓN PARAMÉTRICA DEL PROCESO DE ENGATILLADO LINEAL POR ROLDANA PARA CHAPAS METÁLICAS

The present work, focus on the parametric optimization of geometric parameters for Roll Hemming process. Here, the parameters of interest are the Roller radius, the angle for pre-hemming stage and the fillet radius. The main objective is to improve the quality parameters of the process: Roll-In, Roll-Out and wrinkling. Furthermore, a comparison between results generated, in numerical and experimental studies, with optimum and non-optimal parameters, is presented. Finite Element Analysis (FEA) Software, ANSYS Workbench 15® was implemented for numerical simulation of the process. For the experiments, a 6 degree of freedom (DOF) NACHI SRA210 industrial manipulator was used. From numerical results, 2 Rollers were developed with optimum (10.18 mm of radius) and non-optimal (25 mm of radius) parameters. Multiple tests of roll hemming in straight paths were performed on several 0.9 mm thick Aluminum sheets 6011 (120 x 100 mm2). Similar to simulation, the analysis of the obtained results shows that the Roller with optimum parameters generates the best quality in hemmed samples.

ACEROS AVANZADOS: COMPARACIÓN DEL COMPORTAMIENTO MECÁNICO EN EL ESTAMPADO DE UN TRAVESAÑO DE AUTOMOVIL

One of the fundamental objectives of the automotive industry today is the fuel economy; therefore, reducing vehicle weight has been pushed to the limit especially in the new body designs, without neglecting the passengers passive safety that these structures should provide. Thus, the achievement of these goals is only possible through the implementation of advanced high strength materials along with new design techniques and their associated manufacturing processes. In this investigation, a study of the implementation of three steels, categorized by the AISI, as advanced high strength steels (AHSS) in the manufacture of a cross bar is done. The results obtained are compared each other and with similarly obtained results considering a conventional high-strength steel (CHSS) possessing superior forming properties, but lower resistance properties regarding AHSS considered in this study . To this goald the foundation of the simulation process all necessary operations are presented to perform the sheet forming of a cross car for commercial vehicle floor and a comparative performance takes place between the four selected steels. A safety factor regarding the FLD curve is proposed. The use of appropriate material models of deformation processes involved in forming sheet and the correct definition of the mechanical properties associated with them are essential.

MODELADO TRIDIMENSIONAL DE RUGOSIDAD SUPERFICIAL PARA EL PROCESO DE BRUÑIDO

Ball burnishing is a plastic deformation process that improves the surface quality of mechanical parts decreasing roughness. The surface roughness is an important parameter of study; it is known that affects friction, lubrication and wear. In this work, a general methodology for finite element and a programming routine based on Parametric Design Language was developed and validated. This methodology is useful to generate parametric models of three-dimensional rough surfaces in a commercial software of finite element. The routine produces a random surface roughness using the mean (x ?) and standard deviation (s) of a normal distribution of real surface roughness. The routine was used to generate roughness models of rectangular and cylindrical specimens. The nodal density for generating roughness and repeatability for a given surface finish were evaluated to optimize the modeled surface roughness. The numerical results show a good correlation to the experimental results. In a future, the routine can be used to generate models through the finite element method to simulate any machining process with random roughness and this enable to study the processes, allowing reducing the high costs of experimental tests.

Optimización topológica de una bovedilla de espuma de poliestireno con mezcla de densidades

RESUMEN Los procesos de manufactura tradicionales para fabricar bovedillas de espuma de poliestireno (EPS) se limitan a producirlas en una densidad uniforme dentro de la pieza a partir de cierta longitud; estas piezas son ampliamente utilizadas en la construccion de casas en Mexico. Sin embargo, al analizar las condiciones de carga a las cuales se somete la bovedilla durante su uso, resulta evidente que existen zonas de material que presentan bajos valores de esfuerzo. Recientemente se han desarrollado nuevas tecnologias de moldeo continuo de EPS para producir piezas con mezclas de densidades localizadas por zonas, lo cual ha llevado a considerar una optimizacion que proporcione informacion sobre la distribucion optima de materiales de diferentes densidades, de tal forma que se disminuya la masa de materia prima utilizada sin afectar la resistencia mecanica global requerida en la pieza. Uno de los metodos aplicados en procesos de optimizacion en la industria automotriz, aeronautica y construccion es la optimizacion topologica. Para realizar este proceso de optimizacion es necesario conocer de manera precisa las propiedades mecanicas del material que conforma la pieza. El comportamiento de la bovedilla de EPS utilizada en la industria de la construccion es analizada en este trabajo. Este elemento constructivo opera bajo cargas de flexion y falla debido a esfuerzos de tension en las fibras inferiores de la pieza. Se realizaron pruebas uniaxiales de tension para determinar las propiedades mecanicas de cada densidad utilizada. El comportamiento del EPS es analizado con un modelo elastico multi-lineal utilizando el metodo de elementos finitos basado en la tendencia de las curvas experimentales. La bovedilla de EPS actualmente es fabricada con material de densidad 12 kg/m3. Se utiliza el metodo del criterio optimo (OC) para el proceso de optimizacion. Con esta optimizacion se obtiene un ahorro del 15% del material conservando la misma resistencia mecanica de la bovedilla base.