Reverse Extraction And Reuse Of Five-axis NC Machining Planning Information For Free-form Surfaces

The form of free-form surface is complex and diverse,and its appearance is beautiful.However,CNC machining is difficult and the manufacturing cost is high.Therefore,its trajectory planning is the core content of CNC machining.This paper starts from the experience of valuable numerical control planning of existing curved surfaces,reuses processing information,inherits the successful experience and inspiring knowledge of CNC machining experts,and improves the efficiency and level of CNC machining planning.This reuse proposes a method of “reusing CNC machining planning information”to provide a planning strategy for tool path planning of similar surface NC machining.Based on the similar surface reusable similar NC machining method,the NC machining parameters of the similar surface NC machining information are inversely extracted,and then the machining parameters are locally modified according to the similarity,and the NC machining planning strategy of the surface to be machined is obtained.The second development process produces a numerical control machining program,and the experimental comparison data proves the effectiveness of the method.The article mainly uses NC machining examples generated by UG software as the research object.Based on 3D open source function library Open CASCADE(OCC)and Microsoft Visua Studio 2010(referred to as VS2010)as the program development environment,calculate the curvature,normal vector and tangent vector of free-form surface.And the data information such as the tool position file extraction,using the programming to realize the information extraction and reuse of the NC machining tool path,can not only improve the level of CNC machining planning,but also inherit the valuable experience of CNC experts for the enterprise.(1)The calculation method of inverse extraction of tool location and tool axis vector information from NC code is studied.By studying the kinematics theory of machine tool,the tool position in the CLSF file from the data points in the NC file is derived.The calculation formula of point coordinates and tool axis vector realizes the goal of extracting the tool position and the tool axis vector on the surface from the NC program,which provides a theoretical basis for further realizing the reverse extractionprocess of NC machining information.Finally,the reverse extraction calculation process is realized by VC programming,and the tool position obtained by reverse extraction is obtained.After comparison with the tool position obtained by UGNX software,the conclusion is correct.(2)For the spatial tool attitude in five-axis NC machining,the spatial rotation angle inverse extraction algorithm of the tool axis vector in the local coordinate system is proposed by theoretical derivation.By referring to the tool posture of the existing curved surface,the theoretical basis is provided to further determine the similar tool posture of the surface to be machined,and the inverse data extraction algorithm is correct by the actual data verification.(3)Study the influence of NC machining parameters on the tool path,and propose the extraction algorithm of each parameter information,then use the programming method to extract the NC machining information from the CLSF file,realize the one-time extraction of each CNC parameter information,and the actual setting.The values are compared to prove that the parameters extracted by the method are consistent with the original setting data,thus proving the correctness of the extraction method.Finally,by analyzing the influence of the local curvature of two similar surfaces on the NC machining parameters,the method of reusing CNC machining information is obtained.The experimental verification proves that the method is reasonable and effective.