Deformation Suppression Method For Thin-walled Parts Under Stable Cutting Condition

Thin-walled parts are widely used in aerospace field because of its feature of light weight,compact structure and so on.However,due to the hash work condition,it must be made by difficult-to-machine material.As a kind of typical difficult-to-machine material,TC4 has the characteristic of light weight,corrosion resistant,heat-resisting,high specific strength and good mechanical property.As a result,it becomes the ideal material for the manufacturing of turbine blade and turbine.However,because of the low thermal conductivity,low ductility,high hardness,low elastic modulus of TC4,the processability is poor.Though the traditional mechanical manufacturing method can realize the high precision manufacturing,the machining efficiency is quite low that severely restrained the widely use of components made by difficult-to-machine material.High-speed machining provides an efficient approach for using them widely.As the rigidity of thin-walled parts are quite low,and the cutting force when machining difficult-to-machine material is relatively large,the machining vibration and deformation become very notable among the high-speed machining process,which not only influences the machining quality of thin-walled parts,but also restrains the improvement of machining efficiency.Consequently,the investigation of deformation suppression method for difficult-to-machine material thin-walled parts under stable cutting condition has high value in engineering application.The purpose of this study is to diminish the cutting deformation of thin-walled parts under stable cutting condition.Through the optimization of cutting parameters under stable cutting condition and the reasonable redesign of cutting path,then by the method of cutting deformation compensation based on the modification of cutting location point,the thickness uniformity of thin-walled parts can be guaranteed in high-speed machining process,so as to realize the high quality and high efficiency machining.The main research contents are as follows:Firstly,the stable domain of thin-walled part is worked out based on the typical stable domain solving method,and the stable domain boundary curve with respect to spindle speed and axial cutting depth can be obtained,so that the axial cutting depth range of process system can be determined,so as to provide a reference for further investigation.Secondly,different from the former calculation method which ignores the rigidity variation among the cutting process of thin-walled parts,the rigidity changing along with the removal of workpiece material is considered in this study.By doing this,the machining efficiency can be maximized under stable cutting condition.Then,under the stable cutting condition,aiming at reducing the machining deformation and improving the surface quality,the cutting parameters are optimized.The cutting parameters are primary elected for finding suitable cutting parameter range by the designing of single factor experiment about spindle speed,feed per tooth and axial cutting depth.Next,according to the primary elected parameter range,response surface method is used to do the orthogonal experiment,so as to find a suitable cutting parameter combination which leads to a smaller cutting force and diminishes machining deformation.Moreover,the cutting force forecast model can be obtained by multiple regression fitting method which provides an efficient approach for the estimation of cutting force.Finally,combined with the optimized machining parameters combination,and analyze the influence of different cutting tool path on machining deformation and quality of thin-walled parts,the reasonable cutting tool path can be worked out so as to diminish the machining deformation of high-speed machining of thin-walled parts.On this basis,a deformation compensation method for thin-walled part based on the cutter location point modification is proposed,so as to guarantee the thickness uniformity of thin-walled parts,and improve the machining geometry accuracy.The above research contents provide some references for further investigation of difficult-to-machine material thin-walled parts machining deformation and at the same time is a guidance for the actual production and processing.