Research On Key Technology Of FDM Based Composite Processing

The parts made of additive will show obvious step effect on the inclined or concave convex surface,which can not meet the surface accuracy requirements of the actual formed parts,w hile the machining accuracy of reducing material is high,but the machining flexibility is poor.The advantages and disadvantages of the two technologies are fully utilized to realize effective complementarity.The integration of CNC processing and additive manufacturing,i.e.the flexibility and speed of additive manufacturing,as well as the dimension and surface accuracy of additive manufacturing,can not only improve the production efficiency,reduce the production cost,broaden the range of product raw material processing,but also reduce the use of cutting fluid in the production process,and ensure the production cost Environment protection has a broad application prospect.However,at present,the composite processing technology for increasing and decreasing materials is still not mature,especially when obtaining the composite processing code for increasing and decreasing materials,it integrates the increasing material code and reducing material code manually,with low degree of automation.In this paper,the adaptive layering method based on STL data model,the tool path planning based on STL data model,and the development of the composite software system for increasing and decreasing materials are studied.The additive processing code,the additive processing code and the additive processing code can be automatically generated in a software system.The main contents of this paper are as follows:(1)An adaptive hierarchical algorithm based on cross-sectional area gradient.Using-VC++6.0 software platform to realize the reading and display of STL model,and using the relationship between the properties of triangular patches and the position of layered plane to process the data of STL model.When adjusting the layered thickness of the model,using the triangle segmentation method to calculate the section plane contour area product and adjust the layered thickness,the feasibility of the adaptive layered algorithm is verified by the design experiment.(2)Study on the influence of heat transfer process on forming quality of FDM.The mathematical model of the extrusion quantity of the important process parameters in the forming process was established.The FDM forming process is simulated by using the command flow input method of ANSYS finite element analysis software and the "life and death element technology ".The temperature field and stress field distribution of layered thickness and forming speed are analyzed,and the influence of layered thickness and forming speed on the accuracy of forming parts is studied.The mathematical model of extrusion amount is modified by analyzing the temperature field distribution of forming parts It is verified by experiments.(3)Tool path planning based on STL data model.For the interference and collision between tool and workpiece caused by tool path intersection,overlap and self intersection,an automatic generation method of tool path based on STL data 3D model is proposed.In this method,the results of STL 3D model data slicing are used as tool contact locus,and the vertex offset algorithm is used to generate tool path which can meet the requirements of NC machining.The interference or collision of tool path can be judged by vector point multiplication,and the tool path can be divided into rings.After the validity of the sub ring is judged,the single connected tool path can be obtained.The automatic generation of tool path of STL discrete triangular mesh model is realized.(4)The development of post-processing software for composite processing of increasing and decreasing materials.In view of the current additive processing code and reducing material processing code need to use their own software for code output,the data processing process of adding and subtracting material composite processing code is complex.In this paper,VC++6.0 software platform is used to develop a composite processing software system,which can automatically read and display STL model,set processing parameters,add G code,reduce NC code,and generate composite processing code.The existing printer in the laboratory is used to test the additive G code,the VERICUT software is used to simulate the additive G code,and the additive composite processing code is tested by the constructed additive composite experimental platform to verify the applicability of the software system.