Research On The Compensation Of Deformation Error And The Optimization Of Tool Position Based On The Fine Machining Of Complex Ruled Surface

Nowadays,with the development of manufacturing industry,aerospace and other front-end fields,China's demand for excellent high-end equipment is more and more urgent.The precision and complex curved surface parts widely used in this field are put forward higher requirements in processing efficiency,forming accuracy,yield and other indicators.Complex ruled surface is a typical feature of this kind of complex parts.Generally,it is formed by side milling of multi-axis CNC machine tool,but in the process of machining,the tool always moves according to the ideal path without considering the influence of tool deformation,which leads to the problem of machining accuracy.Therefore,based on the analysis of the geometric characteristics of complex ruled surface,the theory and strategy of tool path planning,milling force modeling,and tool deformation error prediction and compensation are deeply studied in this paper,in order to improve the overall machining quality and machining qualification rate of such complex curved surface parts.The main contents are as follows:Based on the analysis of geometric characteristics of complex ruled surface,a tool path point planning strategy for its side milling is proposed,including the equal bow height error interpolation method based on the boundary line of ruled surface to determine the position of tool path point and the planning algorithm to determine the tool position and orientation at the interpolation position.A simulation example is designed to verify the superiority of this planning method by comparing with the tool path automatically generated by the software.It realizes that the tool path points are as few as possible within the allowable range of the bow height,and the bow height error of the machined surface is kept uniform.Based on the kinematic analysis of 5-axis CNC machine tool,a milling force prediction model considering tool runout,single multi tooth cutting and complex machining path is established,including the establishment of coordinate conversion relationship between tool and workpiece,the definition and parameter identification of tool eccentricity,the analysis of effective contact range between tool and workpiece based on point cloud discrete method,and an equivalent instantaneous undeformed chip thickness model is proposed by using the idea of parametric compensation.The accuracy of the milling force model is verified by comparing the simulation value with the measured value.Based on the analysis of the actual distribution of the milling force on the tool in side milling,the tool deformation is accurately predicted by the superposition of deflection deformation along the normal direction of the workpiece surface.According to the specific analysis of the tool deformation,a more accurate tool position and orientation adjustment criterion is proposed,and the off-line compensation of the tool deformation error in machining is realized by combining the principle of image iterative compensation of the deformation error.In addition,the least square method is used to establish the functional relationship between the deformation compensation value and the corresponding radial milling force.The validity of the compensation model is verified by comparing the surface profile errors before and after compensation,and the overall machining surface accuracy of complex ruled surface feature parts is improved.