Claudiu-Florinel Bisu

Dynamic Behavior Analysis for a Six Axis Industrial Machining Robot

The six axis robots are widely used in automotive industry for their good repeatability (as defined in the ISO92983) (painting, welding, mastic deposition, handling etc.). In the aerospace industry, robot starts to be used for complex applications such as drilling, riveting, fiber placement, NDT, etc. Given the positioning performance of serial robots, precision applications require usually external measurement device with complexes calibration procedure in order to reach the precision needed. New applications in the machining field of composite material (aerospace, naval, or wind turbine for example) intend to use off line programming of serial robot without the use of calibration or external measurement device. For those applications, the position, orientation and path trajectory precision of the tool center point of the robot are needed to generate the machining operation. This article presents the different conditions that currently limit the development of robots in robotic machining applications. We analyze the dynamical behavior of a robot KUKA KR240-2 (located at the University of Bordeaux 1) equipped with a HSM Spindle (42000 rpm, 18kW). This analysis is done in three stages. The first step is determining the self-excited frequencies of the robot structure for three different configurations of work. The second phase aims to analyze the dynamical vibration of the structure as the spindle is activated without cutting. The third stage consists of vibration analysis during a milling operation.

The milling process monitoring using 3D envelope method

This paper proposes a method to vibration analysis in order to on-line monitoring of milling process quality. Adapting envelope analysis to characterize the milling tool materials is an important contribution to the qualitative and quantitative characterization of milling capacity and a step by modeling the three-dimensional cutting process. An experimental protocol was designed and developed for the acquisition, processing and analyzing three-dimensional signal. The vibration envelope analysis is proposed to detect the cutting capacity of the tool with the optimization application of cutting parameters. The research is focused on Hilbert transform optimization to evaluate the dynamic behavior of the machine/ tool/workpiece.

Analyse du comportement dynamique d’une broche de machine-outils

L’apparition de vibrations, ou bien des regimes instables, est induite par l’interaction dynamique du processus de coupe avec le systeme elastique de la machine-outil dans differentes conditions de travail. L’objectif de ce travail est de developper un modele dynamique applique au processus de fraisage pour realiser la surveillance du processus, l’analyse et l’optimisation des conditions de coupe lors du contact outil/piece/machine. Pour mettre en place ce protocole et atteindre les connaissances approfondies des phenomenes dynamiques nous effectuons une etude de ceux-ci divisee en deux parties : la machine et le processus de coupe. Une analyse dynamique detaillee de la machine est obligatoire avant de modeliser les phenomenes vibratoires presents lors de la coupe.

Link between Chips and Cutting Moments Evolution

The better understanding of the material cutting process has been shown with the benefit of the forces and moments measurement since some years ago. In paper, simultaneous six mechanical components and chip orientation measurements were realized during turning tests. During these tests, the influence of the depth of cut or feed rate has been observed and a link between the chip orientation and the moment vector orientation or the central axis characteristics has been shown. Nomenclature * corresponding author