Juan de Juanes Márquez

Command shaping for micro-mills and CNC controllers

Micro-milling requires both high speed and high accuracy in order to economically produce parts with features on the scale of 1 micron. Because micro-mills are small, they are more flexible than traditional large scale machines and therefore vibration is a problem. Since they also require high positioning precision, even small vibrations of the cutting tool are also an issue. This paper presents a nonlinear command shaping technique to reduce the vibrations of a micro-mill which can be implemented with a standard CNC controller. The robustness of this technique to modelling errors and disturbances is investigated. Theoretical proofs and experimental demonstrations of the command shaping technique are presented. The improved performance from the command shaping technique enables higher throughput and improved accuracy of the machine.

Generic Mathematical Model for Efficient Milling Process Simulation

The current challenge in metal cutting models is to estimate cutting forces in order to achieve a more accurate and efficient machining process simulation and optimization system. This paper presents an efficient mathematical model for process simulation to evaluate the cutting action with variable part geometries of helical cutters and predict the cutting forces involved in the process. The objective of this paper has been twofold: to improve both the accuracy and computational efficiency of the algorithm for cutting force estimation in peripheral milling. Runout effect and the real tool tooth trajectory are taken into account to determine the instantaneous position of the cutting flute. An expression of average chip thickness for the engaged flute in the cut is derived for cutting force calculations resulting in a more efficient process simulation method in comparison with previous models. It provides an alternative to other studies in scientific literature commonly based on numerical integration. Experiments were carried out to verify the validity of the proposed method.

Intelligent Decision System Based on Fuzzy Logic Expert System to Improve Plastic Injection Molding Process

Intelligent Systems are the best way to manage complex industrial processes with a high number of process parameters, like injection molding process. Specifically, Fuzzy Logic is a solution to estimate if the qualitative inspection of parts produced allows us to determine correct process parameter value setting to produce good quality parts. This paper shows an intelligent decision system based on Fuzzy Logic techniques designed using defect behavior tendency curves as membership functions. These functions are improving with dynamics and adaptive regression membership functions based on the assessment of quality for a given part done by an operator. The implementation of this intelligent decision system designed for injection molding process shows that is able to transform a qualitative variable deduced of qualitative injection inspection of part defects, into a quantitative inspection, identifying the correct process parameters. Experimental results show that the effectiveness is improved and also reduces the time of a process in a 40%.

Optimización del Proceso de Microfresado mediante la Reducción de Vibraciones empleando Técnicas de Generación de Ordenes de Movimiento

espanolSe ha desarrollado un sistema de control que permite generar ordenes de movimiento sobre un sistema de microfresado existente. El sistema de control permite reducir el error de seguimiento en las trayectorias de mecanizado y por lo tanto permite aumentar las condiciones de corte y aumentar la productividad del proceso. Se hace uso de tecnicas de reduccion de vibraciones, basadas en el empleo de ordenes de accionamiento especiales y se propone una solucion para el seguimiento de trayectorias de mecanizado. El trabajo muestra que se puede mejorar hasta en un 65% el error de seguimiento sobre una trayectoria de mecanizado con movimientos realizados a una velocidad de 1500 mm/min. EnglishA control system has been developed which permits implementation of command shaping in an existing micromilling system. The control system allows reduction of machined trajectory following error, and thus allows improving the cutting conditions and the productivity of the process. Techniques of vibration reduction are employed based on the use of special command shaping orders, and a solution is proposed for tracking machining operations. The study shows that up to 65% improvement can be obtained over trajectory following error, with movements done at feed speeds of 1500 mm/min.