Active control of machine tool vibrations in external_精品.ppt

Active control of machine tool vibrations in external turning operations Authors: L. Andren, L. Hakansson, and I. Claesson Published June 2003 Presentor: Scott Peterson Date: Oct 29, 2008 * Introduction Function of Paper The purpose of this paper is to validate a method of vibration reduction in external turning operations utilizing a system which combines an actuator control by an algorithm generated by an accelerometer to counteract and dampen the vibrations. * Introduction Why is this important? Vibrations during a cutting operation affect the accuracy of the machining, which in turn affects the surface finish. Severe noise is also an important factor which is induced by tool holder vibrations. * Introduction References * Models and design Principles This process relates to many areas of the course. By reducing vibrations we improve the surface finish, something very pertinent to manufacturing. It also affects the life of the cutting tool because a tool operating under more vibrations will experience more stresses and fail sooner. * Models and design principle Parameters and Design -Cutting trials performed on a MAZAK 250 quickturn lathe -Piezoceramic actuator is able To apply loads up to 1000N -Workpiece material is Chromium Molybdenum nickel steel -cutting speed = 80m/min -depth = 0.9mm -feed rate = 0.25mm Workpiece diameter 100mm (negligible workpiece vibrations) * Models and design principles Challenges Reduces stiffness (20%) Harsh environment for electronics Cutting operation has non-stationary properties Actuators excite the structure such that the vibration level is minimized. * Models and Design Principles Control System – Filtered X LMS algorithim * Results The tool holder is attenuated by aprx 40dB using the active control system. * Results The finish of the surface is improved significantly * Conclusions Practical for industrial use? Technical advancement? Industries most impacted? * Conclusions *