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Cold extrusion spur gear precision forming technology saves material because of its high production efficiency , to ensure the dimensional accuracy of parts , tooth surface quality, high load capacity and product quality comprehensive advantages, become spur gear forming a kinds of trends. But the spur gear are not allowed undercut, so extrusion mold design have a certain degree of difficulty. Flow curves and surfaces can greatly reduce the appearance of moving objects on the object forward the process fluid resistance , surface modeling is a new direction of development. This thesis is based on this theory, the stream function introduction of CAD design, design a line with rheological properties of metal extrusion transition chamber , to ensure uniformity of metal flow increase and improve the performance of the metal flow , reduce product twisting and bending , reduce forming pressure and improve the accuracy of the gear forming has a positive meaning . In this thesis, the extrusion cavity mathematical modeling, geometric modeling , interactive graphics programming and CNC machining CNC automatic simulation aspects. First, we apply the principles of fluid mechanics to analyze flow curves and surfaces derived parametric equations , to achieve the extrusion cavity mathematical modeling . In mathematical modeling, the use of Bezier curve fitting, curve approaching flow . And in accordance with the actual situation of the gear contour line to divide it into five sections : the root circle segment , the transition curve segment , segment involute tooth fillet top section and the addendum circle segment , the entire extrusion chamber is divided into five patches were fitted with five sets of parameters equation to describe ; followed geometric modeling , we use the mathematical model , using Pro / ENGINNEER software first create curvilinear grid , and then create the patch , and finally the surface blending , the establishment squeeze pressure chamber geometry ; Finally, the geometric model created in Pro / MANUFACTURE module , the realization of interactive graphics CNC automatic programming and CNC machining simulation . The research projects in accordance with the direction of modern manufacturing CAD / CAM trends , carried out on the spur gear precision forming of research, the research will promote the application of advanced forming technology , production of high precision gears to play an active role for the development of China's precision forming theories and techniques to make some contribution .
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