Research On Chatter Stability And Surface Quality Of Thin-walled Parts Of Titanium Alloy In Milling-grinding Process

With the rising demand for equipment performance from all aspects of life,an increasing number of components adopt thin-walled parts of titanium alloy.This kind of thin-walled workpiece is formed by plenty of rib plates,side walls and webs.At the same time,it gives rise to a more difficult process of machining and relatively poor processing technology that such parts have a large-size dimension,a less stiffness and complex structures,etc.Therefore,how to realize the target which makes the machining of thin-wall workpiece high accuracy,high efficiency and high stability becomes an urgent problem to solve.This paper aims at studying the force conditions of thin-walled parts of titanium alloy in the course of milling processing and sets up a mechanical model of ball-end mill in the process of machining thin-wall components.Besides,the text brings in relative transfer function,that is to say,it gets the transfer function among ball-end mill,grinding head and workpiece as well as two relative transfer functions between ball-end mill and workpiece,grinding head and workpiece.And then,it establishes the model of the chatter stability about milling and grinding.What is more,this paper focuses on parametric analysis of the model and verifies the analytical conclusions through experiments.Thus,the concrete research details are as follows.Firstly,according to the geometric characteristics of ball-end mill and taking the double mechanisms of cut and plow in the course of milling into consideration,the ball-end mill is divided into multiple micro units along the axis direction,further builds the milling force model of micro units.On the basis of the practical situations of ball-end mill in the milling operation,the.integration of milling force is got in the processing contact region.Consequently,the total milling force of cutting tool is obtained.After that,the text converts the total milling force to a form of Fourier mode by using Fourier transform and builds a milling force model which is convenient to be solved.Secondly,through respectively analyzing the machining characters of milling and grinding,this article selects three milling parameters,including spindle speed,milling depth and feed speed.Then,it constructs a test bench in order to do experiments and uses grinding head speed,feed speed and grinding thickness as the elements of orthogonal experiment.Thirdly,this essay introduces the relative transfer function.According to the modal test,it gains both relative transfer functions of ball-end mill,grinding head and workpiece and the above mentioned functions between ball-end mill and workpiece,grinding head and workpiece.In addition,the paper comes up with the chatter stability model in the process of milling and grinding of thin-walled parts of titanium alloy.On the ground of MATLAB software,it gets the lobe graph of chatter stability.Sequentially,the influence rule of every parameter on chatter is received.Finally,the text makes use of 3D profiler to measure the thin-walled parts of titanium alloy which have already been machined by milling and grinding technologies.After dealing with the experimental data,it analyzes the change rule and tendency of thin-walled parts of titanium alloy surface quality after milling and grinding processes as a result of different machining parameters.