Research On Interference Prediction Of NC Machining For Subdivision Surface Based On Multi-resolution Mesh Segmentation

In order to solve the manufacturing requirements of high-end equipment and high-performance products,digital design and data-driven are the key steps to achieve product manufacturing accuracy.How to achieve control of the production quality of complex products is one of the important issues in current research.Subdivision surface NC machining technology has become an important research direction in the field of numerical control processing.Since subdivision surfaces usually represent high-precision complex surface models,local processing interferences are likely to occur in the machining process.Moreover,the huge amount of data processing makes the subdivision surface local processing interference become the main problem of subdivision surface NC machining technology.In this paper,based on the Catmull-Clark subdivision surface method,the related problems such as local processing interference prediction and optimal small tool size calculation in subdivision surface NC machining are discussed.There are mainly the following aspects:(1)This paper analyzes the relevant features of local processing interference,and introduces the basic theory of the subdivision surface method to construct a machining model.Using the characteristics of cell data structure,the fragment representation of Catmull-Clark subdivision surface is realized.Based on the characteristics of multi-resolution representation of subdivision surface model,the construction of subdivision surface models with different machining accuracy is realized,and the calculation of relevant geometric properties of subdivision surface models is elaborated,which provides important theoretical support for the follow-up research of the subject.(2)Local machining interference detection of machining model based on space constraint method.By analyzing the spatial constrains of the cutter location,cutter contact and its normal vector information,a method for local interference detection of subdivision surface model is established.Compared with the interference detection method of using curvature matching,the space-constraint method is more efficient for performing local processing interference detection.Moreover,the curvature matching detection method has limitations,but the space constraint detection method is applicable not only to a ball end mill but also to an face milling cutter and a ring mill.(3)Based on patch morphology analysis and multi-resolution sampling technology,the local interference prediction of machining model can be realized quickly.Based on the patch morphology analysis,the local processing interference area within the processing model is quickly searched for.Then,the interference-detecting unit is used to detect the local interference.Using the multi-resolution sampling technology and the space constraint method,the area of each concave curved surface is most likely to be affected by the local processing interference region.Taking the vertex of the most prone to localized interference region as the research object,combined with the constraint conditions such as knife contact,tool location and its normal vector information,a method for calculating the optimal small tool size was established to realize subdivision surface model NC machining.The local processing interference prediction,this method provides an important reference for the selection of tool size in the numerical control machining process.