Papers by Keyword: Robotic Machining

Abstract: Robotic machining is an attractive, cost-effective, and flexible alternative for basic machining applications. Having these characteristics, industrial robots are assumed to be the next generation of machine tools. But, due to weaker structure of robotic manipulators in comparison to conventional CNC machines, robotic machining processes are more subject to unwanted detrimental vibrations. At this work, simulations are realized in Time-Domain using the linearized robot structure model as transfer function of chatter block diagram and end milling force as machining force model. This article presents a new technique for simulating and analyzing the possibility of happening chatter vibrations at different values of machining parameters considering structure and configuration of the studied robot. Results show that limit of chatter occurrence is dramatically affected by changing robotic machining configuration.

Abstract: The robotic machining is one of the most versatile manufacturing technologies. Its emerging helped to reduce the machining cost of complex parts. However, its application is sometimes limited due to the low rigidity of the robot. This low stiffness leads to high level of vibrations that limit the quality and the precision of the machined parts. In the present study, the vibration response of a robotic machining system was investigated. To do so, a new method based on the variation of spindle speed was introduced for machining operation and a new process stability criterion (CS) based on acceleration energy distribution and force signal was proposed for analysis. With the proposed method the vibrations and the cutting force signals were collected and analyzed to find a reliable dynamic stability machining domain. The proposed criterion and method were validated using data obtained during high speed robotic machining of 7075-T6 blocks. It was found that the ratio of the periodic energy on the total energy (either vibrations or cutting forces) is a good indicator for defining the degree of stability of the machining process. Besides, it was observed that the spindle speed with the highest ratio stability criterion is the one that has the highest probability to generate the best surface finish. The proposed method is rapid and permits to avoid trial-error tests during robot programming.

Abstract: The interaction force and the environments uncertainties are the most challenges for robotic material removal process. The conventional constant force control methods for the deburring process have the inherent characteristic of leaving the deburred surface as an imprint of the original. A process force model considering the burrs variation is presented to predict the contact force in robotic machining process. A self-tuning fuzzy strategy is adopted to implement the on-line compensation for the static error caused by the traditional impedance controller. The fuzzy controller is adjusted by an updating factor to select the most appropriate fuzzy rule set based on the measured performance results. Simulation results show efficacy of the proposed method in robotic machining process, and the control performance is better than that of a traditional impedance controller.