Technologies Research And System Development Of The CAD/CAM Of Non-circular Gear With Random Pitch Curve

Non-circular is a kind of mechanical transmission parts that can realize variable gear ratio, which has many merits, such as stable and precise transmission, big load bearing capacity and so on. The pitch curves of non-circular gear have a great variety and complex shapes, the calculated pitch curves from special motion demands are often be expressed as segmenting curve or list curve, which have not a unified mathematical expression form. For a new designed non-circular gear, the check analysis, model building, machining data generating and virtual manufacture verification need to be conducted with new developed program usually, which make the design and manufacture cycle of non-circular gear is long and limit the popularization and application of non-circular gear. Therefore, research on the unified method of design and manufacture of non-circular gear with random pitch curve and develop the corresponding program module have significant practical application value.This paper make the intensive research to the key technology about CAD/CAM unified module development of non-circular gear with random pitch curve, analyze the mathematical expression method to unify all kinds of non-circular gear pitch curves, research the solid modeling technology of non-circular gear with random pitch curve, deduce the machine tool linkage mathematical models of non-circular gear hobbing and shaping, and then realize the non-circular gear machining codes generating and virtual manufacture verification. The CAD/CAM system development of non-circular gear with random pitch curve is conducted by secondary development to3D modeling software SolidWorks.First, the common design methods of non-circular gear with random pitch curve are summarized, and the design examples are listed to verified those methods. The expression demands of random pitch curve are analyzed, and then the piecewise cubic splines are used to fitting random pitch curve, which unify the polar coordinate expression form of non-circular gear pitch curves.Second, the solid modeling method of non-circular gear is analyzed, and the mathematical models that the rack cutter or gear shaper make pure rolling along pitch curve when pitch curve is fixed are deduced. And then, the non-circular gear solid modeling is realized through Boolean subtraction between the gear billet and cutter model. Third, the machine tool linkage mathematical models used in non-circular gear hobbing and shaping are deduced, the machining data calculation methods are analyzed based on the linkage models, and then the validity of machining linkage mathematical models and machining data are verified by virtual manufacture.Fourth, on the basis of the comprehensive analysis of demands, design process and function implementation methods of CAD/CAM system of non-circular gear with random pitch curve, the solid modeling module and virtual hobbing and shaping modules are integrated, and then the development of CAD/CAM system of non-circular gear with random pitch curve is conducted.Fifth, a design and manufacture example of non-circular gear with random pitch curve is given, and making test to the CAD/CAM system.