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

STUDY OF IN VITRO ANTI-INFLAMMATORY ACTIVITY OF ETHNOMEDICINAL PLANTS OF SIKKIM VISCUM ARTICULATUM AND ACORUS CALAMUS

Objective: The present study was carried out to evaluate the anti-inflammatory property of ethnomedicinal plants Viscum articulatum and Acoruscalamus.Methods: Human red blood cells membrane stabilization method was applied to assess the anti-inflammatory property of both the plants.Results: It was observed that both plant extracts have the anti-inflammatory potential comparable with that of the drug indomethacin. However, A.calamus was found to provide slightly more inhibition of hemolysis (76.8%) than that of standard drug (indomethacin) (72.8%), whereas V. articulatumprovided slightly lesser inhibition (68%) in comparison to the drug. There was the tendency of increase protection along with the increase in theconcentration of the extract, and maximum protection was achieved at the maximum concentration of 5000 µg/ml.Conclusion: The study proves the anti-inflammatory efficacy of both the plants and they hold a good prospect for drug development againstinflammation.Keywords: Anti-inflammatory, Viscum articulatum, Acorus calamus, Sikkim

Self-excited vibrations in turning: cutting moment analysis

This work aims at analysing the moment effects at the tool tip point and at the central axis, in the framework of a turning process. A testing device in turning, including a six-component dynamometer, is used to measure the complete torsor of the cutting actions in the case of self-excited vibrations. Many results are obtained regarding the mechanical actions torsor. A confrontation of the moment components at the tool tip and at the central axis is carried out. It clearly appears that analysing moments at the central axis avoids the disturbances induced by the transport of the moment of the mechanical actions resultant at the tool tip point. For instance, the order relation between the components of the forces is single. Furthermore, the order relation between the moments components expressed at the tool tip point is also single and the same one. But at the central axis, two different order relations regarding moments are conceivable. A modification in the rolling moment localization in the (y, z) tool plan is associated to these two order relations. Thus, the moments components at the central axis are particularly sensitive at the disturbances of machining, here the self-excited vibrations.Comment: 8 page