Virtual Design Of Inverse Rotating Bending Fatigue Cutting Mechanism

Blanking quality directly affects the quality and efficiency of follow-up process. With the developing of processing industries, for different materials, volume and precision requirements, there has been a variety of cutting methods. Traditional cutting methods often have many defects such as low efficiency, energy consumption and poor quality cross-section, while, electrochemical, electron beam blanking methods and other modern methods cost too much for the general cutting requirements. Anti-rotating bending fatigue cutting machine can effectively solve the problem above.Based on crack technical theory and metal fatigue crack fracture mechanism, combining the oretical analysis with practical case, fatigue life of bar under inverse rotating bending is studied, major moving organizations in the machine are designed and virtualy assembled, and its motion simulation and finite element analysis is did.In order to improve the efficiency and quality of fracture, the math model of bar fatigue life is studied at the beginning. Then the assembly model is established with virtual design method. Specifically speaking, the following work is completed in this thesis: First, according to the fact that crack closure phenomenon exists in traditional bending fatigue blank which influence efficiency I improves the mode of fatigue loading to increase stress ratio and establishes a new mathematical model of life prediction. Second, because bar does not rotate in the inverse rotate bending mode, wedge block and lever institutions are designed to solve hydraulics component which supply pre-load force should not rotate, and the motor, hydraulic cylinder and other power components can remain stationary relative to machine frame; Taking into account the adverse effects of friction torque to cross-section's flatness, a self-centering fixture is designed that can transfer fixture load reliably and reduce friction torque between the bar and the fixture; the expansion mechanisiam and counter weight are used to balance the basic shaft in various conditions. Finally, the finite element software ABAQUS are used to do static analysis and modal analysis, which verifies the basic shaft stiffness and provide technical parameters to the choice of speed.Based on the study of the fatigue fracture mechanism and inverse rotating bending fatigue cutting mechanism, the application of crack technical theory is enriched in the paper,meanwhile,theoretical support is provided for the development and application of inverse rotating bending fatigue cutting mechanism.