Machining Error Analysis Of Ball End Milling Cutter For Curved Surface Splicing Area Of Hardened Steel Die

The die surface of automobile outer panel is becoming more and more complex.In order to improve the machining efficiency,mostly large panel dies are spliced by insert-type dies.There is a large proportion of non-uniform and high hardness surface in the machining area,which is easy to cause sudden change of load and cause obvious impact vibration to the tool.This results in instability of tool load and decreases the quality of the machined surface.In this paper,the hardened steel surface die is taken as the research object.And the milling force,milling vibration and machining error caused by tool deformation and impact vibration in the splicing area are modeled are analyzed and predicted.Firstly,this paper analyses the milling state of the ball-end cutter at the seam crossing,and establishes the cutting thickness model at the seam crossing of the ballend cutter milling splicing.The above work is based on the general cutting thickness model,and considers the influence of surface feature pairs and the splicing characteristics of the workpiece.It is based on the instantaneous rigid force model to divide the milling process and establish the milling force prediction model in stages.The prediction model of milling force suitable for surface splicing area is obtained.Secondly,the time-varying delay characteristics of cutting-edge elements were analyzed,and the milling dynamics model considering the time-varying delay parameters was established.Taking the characteristics of die splicing into consideration,the impact vibration of the tool at the splicing joint was analyzed,and the milling dynamic equation of the splicing area with time delay was established.Then,finite element method was used to analyze the force and deformation of the tool,and the error model of the tool yield caused by the tool deformation is established.It is concluded that the error of tool setting of curved surface die increases with the increase of processing inclination angle.A machining error model considering impact vibration was established,which considering the influence of impact vibration on cutting edge trajectory.Compared with the error model of tool deformation,it is more suitable for the prediction of machining errors of milling splices.Finally,the simulation experiment of splicing die milling was carried out.The measurement of machining errors is carried out by 3-D coordinate measuring machine.The experimental results and simulation results were compared to verify that the variation law is basically the same.This research can solve the problem of low machining accuracy of die surface in splicing die and provide theoretical basis and practical guidance for hard milling technology.