Force Prediction For Five-axis Complex Surface Milling With Fillet End Mill

Five-axis surface milling with fillet end mill is wide used in die,aerospace,shipbuilding and other fields.Cutting force is an important parameter to describe milling process,which is closely related to cutting vibration,tool and workpiece deformation,processing efficiency and workpiece processing quality.It is a key and difficult point to study milling process.Taking fillet end mill as research object,using mechanical model and considering tool run-out,this paper establishes a force prediction for five-axis complex surface milling with fillet end mill,which is of great significance both in theory and in practice.The In-Cut Cutting Edge(ICCE)and the cutting force coefficients are the bases for predicting the milling force with the mechanical model and they are the focus of this paper.The main contents of this paper are as follows:(1)The model of Cutter Workpiece Engagement(CWE)is established for five-axis inclined plane milling with fillet end mill.Inclination angle is defined to describe the angle between cutter axis and workpiece surface.Cutter coordinate system is established on inclined plane.Cutter envelope surface,to-be machined surface and previous cutter swept surface are established in cutter coordinate system.Whereupon a parametric model for five-axis wide strip inclined surface milling with fillet end mill is established.The CWE boundary curve is obtained by intersecting the surfaces.The candidate endpoints of the CWE are obtained by intersecting the curves.Because the candidate endpoints are more than one,the feasible endpoints are chosen from the candidate endpoints according to the characteristics of the intersecting points.(2)Algorithms of ICCE are proposed.The ICCE is calculated on inclined plane.Two kinds of ICCE algorithms are proposed,one is CWE-limiting method and the other is the space-limiting method.Both methods can obtain the ICCE.The space limiting method can obtain ICCE without CWE.The cutter edge can be discretized into a series of cutter edge elements.ICCE are obtaiend by judging each cutter edge elements.(3)Force prediction model is established.Considering cutter runout,a formula for calculating the thickness of the chip thickness in five-axis milling of fillet end mil is established.Milling force model is established by combining mechanical thickness of undeformed chip and ICCE.The method to identify cutting force coefficients and cutter run-out parameters is proposed.The instantaneous average milling force of actual working conditions is used to identify the cutting force coefficients.Taking chip thickness and axial position angle as variables,cutting force coefficients are fitted using polyomial.Cutter run-out parameters identification are carried out after cutting force coefficients identification.Cutter run-out parameters are calculated by instantaneous peak force.The relationship between inclined plane and complex surface is transformed into the relationship between cutter coordinate system and workpiece coordinate system.(4)Cutting experiments were carried out on inclined plane and complex surface to validate force prediction model established in this paper,which shows that the predicted milling force agrees well with the measured force in amplitude range and variation range.Cutting experiments were carried out on inclined plane and complex surface,respectively.For five-axis inclined plane machining,the milling force during a cutter revolution is predicted.Surface milling experiments include Z-constant machining and sinusoidal machining.The peak milling force of the cutter along the tool path is predicted.The experimental results show that the predictive force is also in good agreement with the experimental force in both trend and amplitude.The experiment results validate the milling force prediction model.