Research On The Chatter Of Mill–turning CNC

The equipment manufacturing industry is an indispensable strategic industry in the development of national industry,and the machine tool is a symbol of the development level of the national equipment manufacturing industry. As we all know,modern high-speed machines are commonly used in Spindle,it is the ultimate implementation of parts of the machine. And chatter has a direct impact on the accuracy of parts.Using The Mill-turning CNC as the research object,respectively on direct driven rotary power head rest and direct drive turntable for the modal and harmonic response analysis,the sixth order intrinsic mode and the contrast between the two under the excitation of all directions of amplitude.The dynamic equation is established and the traditional kinetic equation model is optimized to make it more accurate.According to the kinetics equation,chatter stability lobes diagram has been got. And using the DEFORM-3D software to verify the simulation results.We also analyze the influence of cutter tooth number, radial depth of cut,feed on dynamic characteristic of machine tool chatter system.The research of this paper provides a theoretical basis for the reasonable selection of cutting parameters and reducing chatter. The main contents of this paper are as follows:(1) Direct-drive turntable and power turret are made for modal analysis and harmonic response analysis.It is found that the dynamic front rest two order natural frequency with spindle speed for the frequency range of 35~12000r/min.During cutting,we should avoid the spindle speed corresponding to the frequency;The theory-maximum amplitude of the direct drive rotary table is 0.0324 mm,the theory-maximum amplitude of the power tool carrier is 2.66 mm.The influence of power turret for machining accuracy is more serious.(2) According to the working theory of the power turret,cutting mode is selected and the dynamic model is deveded,In the milling process,the calculation formula of the cutting and cutting angle ate infored,which can effectively solve the problem of time variation of the dynamic cutting force coefficient.The chatter stability lobes diagram and the cutting depth of the axial direction has been reducted,which the number is 4.8mm.(3) According to the obtained chatter stability lobes diagram,stable region and unstable region has been selected.The X, Y, Z three direction Cutting force changecurve are getted by DEFORM-3D software three-dimensional simulation.By comparison with the change of cutting force change curve,the change of cutting force is affirmed conforming to the prediction we obtained.The average value of the main cutting force data is extracted and the numerical comparison with the empirical formula of the cutting force is obtained which Verify the correction of Deform-3D simulation results.(4) The influence of cutter tooth number,radial cutting depth and feed consequence for the flutter stability of the system are discussed.The stability lobes diagram and cutting force curve are obtained which influced by different tooth numberof milling cutter,different radial depth of cut and feed.With the increase of cutter tooth number and radial cutting depth,stable region is becomed smaller and minimum limit cutting depth is decreased.Contrarily,the stability region and minimum limit depth of cut are both increased when feed is increased.