Font Size: a A A

Study On Milling Cutter Motion And Cutting Force Modeling Considering The Tool Runout

Posted on:2018-05-10Degree:DoctorType:Dissertation
Country:ChinaCandidate:D L ZhangFull Text:PDF
GTID:1362330563495813Subject:Aviation Aerospace Manufacturing Engineering
Abstract/Summary:PDF Full Text Request
The complex shaped,thin-walled and processing highly-precise workpieces are manufactured in the aeronautics,astronautics and aircraft engine industries to meet the requirement of the weight reduction,structural strength controlling and the performance optimization.Obviously,the machining accuracy and the surface quality of the workpiece are influenced by the variation of the cutting force caused by the cutting tool runout.The cutting force is treated as an important physical quantity,which is influenced by the tool runout caused by the spindle error motions and the tool camping error.And the cutting force has an immediate impact on the cutting temperature,which further affects the tool wear and the workpiece surface quality.It is important to note that the tool runout is unavoidable and significantly infuential factor of the instantaneous undeformed chip thickness.In the thin-walled structural components machining,the variation of cutting forces resulted from the tool runout maybe cause the parts scrapping.It is different from previous studies from the standpoint about the result from the tool runout,a milling cutter motion modeling method is proposed in this paper from the standpoint about the reason for the tool runout.This modeling method provide the ability to help the researchers analyse the reasons for the error influencing the tool motion,optimize machining parameters and monitoring machining status.This work is supported by the Nation Natural Science Foundation of China(Grant No.51475381/Grant No.51375395)and the Natural Science Foundation of Shaanxi Province(Grant No.2013JM7001).It aims to monitor the tool wear states timely during the metal cutting,by integrating the milling cutter swept volume model and the cutting force model.Firstly,the milling cutter swept volume model was established considering the rotation motion of a spindle and the tool clamping error,on the basis of research of the major factors affecting the tool motion.With the milling cutter swept volume model,a numerical calculation method of the instantaneous uncut chip thickness was proposed,and the calibration method of the cutting force coefficients and the parameters of the milling cutter swept volume model were presented.Finally,the features to monitor the tool wear state were extracted from the cutting model with tool flank wear.Specific research content includes the following aspects:1)The motion modeling of the milling cutter axis was carried out,considering the spindle motion and the tool clamping error.The instantaneous volume of workpiece cutted is determined by the motion of the milling cutter axis and the milling cutter's swept profile,which is the key to the calculating magnitude of cutting forces.The motion track of the sphere ball of the APIs Spindle Dynamic Analyzer(SPN 300)was treated as the motion track of the bottom of the milling cutter to validate this model.It is worth noting that the PSO(Particle Swarm Optimization)can optimize this problem by iteratively trying to improve a candidate solution with regard to a given measure of quality.So in this paper,the PSO algorithm was presented for searching for the optimum parameters in the feasible area.The results of this experiment showed the measuring data was in concordance with the theoretical results and the calibration method has a good performance of accuracy and robustness.2)a numerical calculation method of the instantaneous uncut chip thickness was proposed based on the model of the milling cutter motion.The calculation method of the instantaneous uncut chip thickness is one of the core problem in the cutting force model.The motion surface model of the tool blade was built based on the model of the motion of the milling cutter axis,and the calculation method of the instantaneous uncut chip thickness was present on the basis of it.Compared with a traditional analytic calculating method,there is no simplification of the motion of the cutter in this method to avoid the loss of the detail of the instantaneous uncut chip thickness.3)A new calibration algorithm of the cutting force coefficients,the edge coefficients and the parameters of the tool motion model was proposed.Based on the calibration algorithm of the instantaneous cutting force coefficients,the one of the constant cutting force coefficients was carried out.Compared with the calibration algorithm based on the average cutting force,it can avoid a series of cutting tests and get the run-out parameters.In order to show the expression forms of the cutting force coefficients,it's defined the reference planes and vectors to represent angular relations in the mechanics of orthogonal cutting and oblique cutting.Depending on the calibrated cutting force coefficients and the numerical calculation method of the instantaneous uncut chip thickness,the calibration algorithm based on the PSO(Particle Swarm Optimization)of the tool clamping error angle parameter?,the tool clamping error radial parameter?,the tool blade clamping parameter?_B was suggested.At last,through the milling experiment,the feasibility of the calibration algorithm was verified.4)A new recognition algorithm for the tool wear condition monitoring based on the model of the milling cutter motion and the model of cutting force was suggested.In the related researches,the method of decreasing the dimension of feature vector is necessary and the accuracy of recognition is easy to be affected by the amplitude of the cutting force caused by the tool clamping error.In order to solve these problems,a new recognition algorithm for the tool wear condition monitoring based on the model of the milling cutter motion and the model of cutting force was proposed.Firstly,the cutting force model with tool flank wear on the basis of the tool wear mechanism and stress distributions on the tool flank was proposed.Secondly,taking advantage of the calculation results of the instantaneous uncut chip thickness and the transform matrix of the local cutting force coordinate,the calibration method of the tool flank wear coefficients can be suggested.Finally,the recognition algorithm for the tool wear condition monitoring was built by treating the tool flank wear coefficients as the recognition feature and using the SVM(support vector machine)theory as the classification approach.Through the verification test,the availability and the feasibility of the recognition model were verified.
Keywords/Search Tags:Milling, Milling force, runout, Swept Volume Modeling, Tool wear condition monitoring, SVM
PDF Full Text Request
Related items