Analysis Of The Influence Of Magnetorheological Excitation Solidification Characteristics On Cutting Vibration Suppression Of Thin-Walled Parts

With the development of manufacturing industry,thin-walled parts are widely used in aerospace,national defense,automobile and other fields because of their light weight,material saving and compact structure.However,flutter will occur in the process of processing because of the poor rigidity,weak strength and complex structure of thin-walled parts,which will make the surface quality of the workpiece worse.Therefore,controlling the vibration in cutting is the key to ensure the processing quality of thin-walled parts.Chatter in milling process not only reduces the surface quality of workpiece,but also causes the damage of tool and machine tool,and reduces the processing efficiency.In the process of mechanical manufacturing,fixture is used to fix the workpiece,make it in the right position,and support the workpiece in the process of processing,reduce the vibration and deformation of the workpiece.Therefore,it is of great significance to design fixtures that can increase the stiffness of the system and reduce the deformation of thin-walled workpieces.Magnetorheological fluids(MRF)can be solidified rapidly under the excitation of an external magnetic field(phase change time is in milliseconds).The liquid-solid phase transition can be easily reversed in normal temperature.In this way,the excellent flow characteristics of magnetorheological fluids can be used to fill the clamping gap flexibly to achieve conformal contact between magnetorheological fluids and the clamping surface of parts,and the part or whole low stress support clamping can be realized by excitation solidification characteristics.At the same time,the controllability of magnetorheological fluid excitation phase transition can also be used to control the dynamic characteristics of thin-walled parts processing system and achieve the suppression of machining chatter.Magnetorheological fluid is used as phase change clamping material,which provides an effective option for reliable and flexible clamping of thin-walled parts.Therefore,MR clamping has unique advantages in ensuring the flexibility and reliability of clamping of thin-walled parts,improving the quality and efficiency of component processing,and reducing the integrated manufacturing cost.Aiming at the problem that the research and application of magnetorheological fluids in the field of vibration suppression of mechanical processing are not perfect enough,firstly,the basic properties of magnetorheological fluids are studied and the different working modes of magnetorheological fluids are compared.A set of cantilever magnetorheological flexible fixture for thin-walled parts working under extrusion mode is designed and the c ircuit and magnetic circuit of the fixture system are reasonably planned.Then,the MRF extrusion experiments are carried out starting from the rheological properties of MRF.A method of adding elastic constraints to the clamping part of workpiece in the M RF is proposed aiming at the magnetorheological fluids working in the pre-yield region.The modal of the workpiece clamped by MRF is analyzed by Ansys software and the clamping effect of MRF under different magnetic fields is evaluated.Modal hammering experiments were carried out to measure the modal parameters of thin-walled workpieces and the simulation results were verified by experiments.Finally,aiming at the problem of machining vibration in milling process,milling flutter stability lobe diagram under different magnetic fields were drawn by using the obtained modal parameters and the cutting experiments of thin-walled parts were carried out by selecting reasonable cutting parameters.The cutting of thin-walled workpieces was carried out separately by changing the excitation current to obtain different magnetic fields.The average cutting depth,workpiece surface quality,chip type and processing noise of the workpieces were compared to measure the clamping effect of MR fixture.The results showed that the flexible fixture based on magnetorheological fluids studied in this paper has obvious suppression on milling vibration and contributes to solving the vibration problem of thin-walled parts processing.