Research On Tool Axis Vector Smoothing Algorithm For Five-axis NC Machining Of Stone Engraving

With the rapid development of the manufacturing industry,the numerical control machining technology of complex curved surfaces is involved in more and more fields such as automobile shell design and aerospace impeller processing.Due to the continuous development of complex surface NC machining technology,NC machining of special-shaped stone products has become possible.At the same time,NC machining has the characteristics of high material removal rate and good surface finish as it can handle geometrically complex workpieces,and thus making the NC machining technology of special-shaped stone products stand out.At present,the NC machining technology mainly includes traditional three-axis NC machining and more flexible five-axis NC machining.Compared with three-axis NC machining,five-axis NC machining is more efficient in the rough and finishing stages.In five-axis NC machining,the tool can be controlled with two additional degrees of freedom,making it suitable for machining complex surfaces.However,with the increase of the degree of freedom,the planning of the cutter axis vector has an increasingly greater influence on the surface machining quality and processing efficiency.This paper proposes a five-axis NC machining tool axis vector control algorithm for special-shaped stone products.By smooth control of the tool axis vector,the tool path with good interference,continuity and smoothness is obtained.The processing quality and processing efficiency of the surface of the shaped stone product gets improved.Firstly,the basic concept of five-axis NC machining is introduced,and the advantages of five-axis NC machining compared to three-axis NC machining are described.At the same time,the kinematics analysis of the existing five-axis NC machine tool is carried out,and the kinematics process of the tool point transformation from the workpiece coordinate system to the machine coordinate system is described,which provides the tool path planning and tool axis vector smoothing control for the special-shaped stone NC machining.Secondly,based on the analysis of the existing method of dividing the surface area,this paper proposes a method for dividing the surface area of special-shaped stone products.Through the reverse engineering technology,the surface model of the surface of the special-shaped stone products is obtained.Based on the analysis of the differential geometry of the surface model and the C-map analysis method,the complex surface is divided into different processing sub-areas.The tool axis vector smoothing control algorithm for five-axis NC machining of stone carving is used as a bedding.At the same time,the related concepts of five-axis NC machining tool trajectory planning and the selection of tool types in NC machining of stone products are expounded.The process of trajectory planning of five-axis NC machining tools for special-shaped stone products is introduced in detail by taking the residual height method as an example.Finally,this paper proposes a method to adjust the tool axis vector by comparing the vector change rate of the tool axis,which not only ensures the processing bandwidth but also keeps the change of the tool axis vector.smooth.At the same time,the effective cutting shape of the flat head knife projected in the feed direction and the calculation method of the processing bandwidth of the flat head knife are described.The theoretical optimal tool axis vector position is proposed due to the influence of the change of tool attitude on the machining bandwidth.Comparing with the change of the cutter axis vector before and after optimization,it can be seen that the algorithm can effectively improve the processing quality and processing efficiency of the surface of the shaped stone products.