Suppression Of Milling Vibrations Via Active Control Techniques

A vibration problem in a mechanical system occurs due to the oscillation of a system about an equilibrium position which leads to a dissipation of energy.Milling is a machining practice of material deduction from a work surface via rotating cutters.It starts by feeding the cutter into the workpiece at a definite course,where the cutter is held at an angle relative to the axis of a tool.In manufacturing industries,a vibration is a common problem associated with the machining of a blade,impellers,and a turbine due to force removal of material from a work surface,and hardness.Also,a vibration in milling occurs as a result of a dynamic interaction between the cutting tool and a workpiece during cutting due to friction,and rotation of the spindle.Such problems cause many negative effects,such as high production cost,machine impairment,poor surface finish,and reduces work quality.However,in the past,many techniques were applied to resolve the machine vibration problem via process damping,passive control,and active control techniques.Owing to the above deliberation,this thesis organizes active control techniques to solve the milling vibration problem of the thin-walled workpiece.Innovative control methods are suggested,to safeguard the machined surface from vibrations,affecting the milling practice.All the active control techniques in this work consider a unique design,which differs from the existing methods.Five active control techniques are described as follows.Firstly,a work delivers a novel approach of damping forced vibration using a proportional-integral controller in the milling process.Secondly,an active control process is developed to address the problem of workpiece-backoff with consideration of bending moment in the modeling and control part.Thirdly,new work is organized to tackle the problem of excited vibration in the milling process using an adaptive controller that considers parameter estimation of the machined surface vibration.Fourthly,a response matrix is presented to control free vibration considering feed rate,tooth passing frequency,and time-varying dynamic milling force coefficients.Finally,a novel H? controller is examined to control self-excited vibration.It provides optimal control for milling vibration suppression.The five different techniques are explained in detail as follows.1.This work delivers a novel approach of damping forced vibration control in the milling process.The intended technique develops a proportional-integral controller by analyzing a time-varying dynamic milling force coefficient.Its application is verified using an active damping device on a steel workpiece,where significant damping performance is realized.The work provides a new vibration control process for industrial purposes.Also,it improves the existing method by considering the depth of cut and a spindle speed variation using a real milling system.An existing work examined a field-programmable gate arrays(FPGA)module.2.In this procedure,an active damping controller is offered to actively damp vibration of a workpiece in the milling process.The research reflects vibration related to the bending moment,of the workpiece due to the applied load.The work differs from the present method,which employed a flexible fixture based on magnetorheological fluid(MR)to solve the bending vibration of the workpiece,using the Euler–Bernoulli beam theory.The main benefit of this controller is to solve the workpiece back-off and decreases vibration on the machined surface.It is assumed that the vibration of the workpiece is proportional to the perpendicular distance between the cutting force and the support point.The proposed system has invented a unique technique that addresses the problem of vibration despite technical hitches in modeling and controller design.3.This work is organized to solve an excited-vibration problem using an adaptive controller.The excited-effect is the most severe form of vibration resulting from the interaction between a previous and current wave of cut.In particular,this new adaptive technique estimates the excited-vibration of the machined surface.It differs from the previous adaptive control scheme,which considered spindle drive dynamics,and the one based on Fourier series analysis,which estimates a cutting force variation matrix.4.This work presents an inventive active response matrix controller design to resolve a free vibration in the milling process.The technique considered feed rate,tooth passing frequency,and time-varying dynamic milling force coefficients.It differs from an existing method that employed a feedback controller based on linear matrix inequality,using multiple delay differential equations.The proposed procedure is technically and economically beneficial.Its advantages are confirmed via experimental work.The arrangement provides a reliable way of tackling vibration in an automated process.5.This work is designed to solve the problem of self-excited vibration using H? optimal control.The main objective is to investigate the effect of an optimized controller in the self-excited vibration control of the milling process.Its main advantage is to increase stabilization.The milling test is designed to observe the effect of the method.