Fracture Research And Simulation Optimization Of Universal Coupling Of Straightening Machine

The main transmission system of roller straightener is the most important as well as the weakest link in the whole straightener system, and it will transfer the motion and torque of the main motor to the straightening roller. The transmission mode of the main transmission system of roller straightener widely used is motor, reduction gear distribution box, safety coupling, universal coupling to the straightening roll. The universal coupling is the key components to transfer motion and torque, and the most dangerous part of the main transmission system,which occurs failures most frequently in the straightener.In this paper,the universal coupling of one straightener is taken as the research object,and a comprehensive analysis is carried out about the universal coupling in the direction of the internal factors and external factors. The main contents are as follows:(1) Torque analysis was carried out on the model of straightening. Straightening torque calculation model is established, and the influence of the wear of straightening roll on straightening torque is analyzed through the finite element simulation. Measures are put forward to improve the torque distribution inequality, and thus the stress condition of the universal coupling is improved;(2) The force analysis was carried out on the universal coupling through the finite element method. The change of stress value and the maximum stress position under the different working angles and the necessity of considering working angle in universal coupling static analysis are obtained;(3) The modal analysis is briefly introduced, and the first 10 order vibration modes and natural frequencies are obtained. First of all, the relationship between the working angle and universal coupling modal is determined according to the changes in the value of the natural frequency of the different working angles; Then, whether the cross shaft universal coupling is a smooth operation is determined through the comparison between the critical speed which is further obtained and actual speed, that is, whether resonance is the cause of the universal shaft fracture accidents is determined;(4) The cause of the universal coupling fracture accident is found according to the results of the static analysis and modal analysis. The universal coupling is optimized aiming at the cause of the accident, and the stress condition before and after optimization were compared;(5) The lives of universal coupling before and after the optimization are studied. Their values of fatigue life, the safety factor and fatigue sensitive coefficient are compared to determine the best optimization method.