Research On Design Of Double Helical Rotors Profile Configuration And Tool Shape-edge

Screw compressor is widely used in the fields of mine, metallurgy, aerodynamic force, refrigeration, etc, in which double helical rotors are the core component. The rotor profile directly effects the performance of the compressor, so it has theoretical and practical significance to study the configuration design of rotor profile and the edge design of form milling cutter for rotor.There are good meshing characteristics for arc-arc envelope, which can realize the surfaces sealing between rotors. According to the meshing theory, curve equations of the arc envelope line which meshes with the known arc are derived, and a set of relatively complete analytical solution method of the rotor profile based on arc-arc envelope line is formed. On this basis, the mathematical model of rotor profile made up with arc-arc envelope line is established. With MATLAB, each tooth curve and its parameters are computed, and rotor profile graphic and meshing graphic are drawn.For the helical rotor profile which is expressed by discrete coordinate points, NURBS provides an accurate construction method of curve and surface, so backward design for rotor profile is deeply analyzed with NURBS method. The calculation model of The rotor feature points, the corresponding node vector, control points and weight factor are determined, then the rotor profile NURBS fitting based on discrete profile points is realized. According to conjugate meshing principle, the calculation model of conjugate profile meshing with the NURBS fitting profile is derived. Aiming at discrete problem of rotor profile, equal arc-length discrete algorithm is proposed, and the rationality of profile discrete is verified by approximation error checking. Then the equal arc-length discrete of rotor profile base on NURBS is realized.The generation principle of tooth surface of helical rotor in three-dimensional design software is studied. On the basis of analyzing date construction of rotor profile, the three-dimensional solid modeling scheme of rotor is designed. Furthermore, three-dimensional solid models of moon rotor and sun rotor are completed, and the assembly and the dynamic meshing simulation for rotors are realized.The forming milling principles for helical rotor surface and the edge design ideas of form milling cutter are deeply analyzed. The calculation model of the cutter-rotor contact conditional expression is solved by NURBS method, and the cutter edge design is realized based on NURBS. The example of cutter is realized with MATLAB, and the cutter is modeled with the obtained data in UG.