Active control of machine tool Active control of machine tool vibrations in external turning vibrations in external turning

operationsoperations

Authors: L. Andren, L. Hakansson, and I. ClaessonAuthors: L. Andren, L. Hakansson, and I. Claesson

Published June 2003Published June 2003

Presentor: Scott PetersonPresentor: Scott Peterson

Date: Oct 29, 2008Date: Oct 29, 2008

IntroductionIntroduction

•Function of PaperFunction of Paper• The purpose of this paper is to The purpose of this paper is to

validate a method of vibration validate a method of vibration reduction in external turning reduction in external turning operations utilizing a system which operations utilizing a system which combines an actuator control by an combines an actuator control by an algorithm generated by an algorithm generated by an accelerometer to counteract and accelerometer to counteract and dampen the vibrations. dampen the vibrations.

IntroductionIntroduction

•Why is this important?Why is this important?• Vibrations during a cutting Vibrations during a cutting

operation affect the accuracy of operation affect the accuracy of the machining, which in turn the machining, which in turn affects the surface finish. Severe affects the surface finish. Severe noise is also an important factor noise is also an important factor which is induced by tool holder which is induced by tool holder vibrations.vibrations.

IntroductionIntroduction

•ReferencesReferences

Models and design Models and design PrinciplesPrinciples

•This process relates to many areas This process relates to many areas of the course. By reducing of the course. By reducing vibrations we improve the surface vibrations we improve the surface finish, something very pertinent to finish, something very pertinent to manufacturing. It also affects the manufacturing. It also affects the life of the cutting tool because a life of the cutting tool because a tool operating under more tool operating under more vibrations will experience more vibrations will experience more stresses and fail sooner.stresses and fail sooner.

Models and design Models and design principleprinciple

• Parameters and DesignParameters and Design• -Cutting trials performed on a-Cutting trials performed on a• MAZAK 250 quickturn latheMAZAK 250 quickturn lathe• -Piezoceramic actuator is able-Piezoceramic actuator is able• To apply loads up to 1000NTo apply loads up to 1000N• -Workpiece material is Chromium Molybdenum nickel -Workpiece material is Chromium Molybdenum nickel

steelsteel• -cutting speed = 80m/min-cutting speed = 80m/min• -depth = 0.9mm-depth = 0.9mm• -feed rate = 0.25mm-feed rate = 0.25mm• Workpiece diameter > 100mm (negligible workpiece Workpiece diameter > 100mm (negligible workpiece

vibrations)vibrations)

Models and design Models and design principlesprinciples

• ChallengesChallenges• Reduces stiffness (20%)Reduces stiffness (20%)• Harsh environment for electronicsHarsh environment for electronics• Cutting operation has non-stationary propertiesCutting operation has non-stationary propertiesActuators excite the structure such that the vibration Actuators excite the structure such that the vibration

level is minimized.level is minimized.

Models and Design Models and Design PrinciplesPrinciples

• Control System – Filtered X LMS algorithimControl System – Filtered X LMS algorithim

ResultsResults

• The tool holder The tool holder is attenuated by is attenuated by aprx 40dB using aprx 40dB using the active the active control system. control system.

ResultsResults

• The finish of the surface is improved significantly The finish of the surface is improved significantly

ConclusionsConclusions

•Practical for industrial use?Practical for industrial use?

•Technical advancement?Technical advancement?

•Industries most impacted?Industries most impacted?

ConclusionsConclusions