Crack Generation And Propagation Analysis Of Universal Joint In Main Drive System Of Plate Mill

Rolling is the work of rolling the main drive system of rolling mill,and the slab is rolled into fixed size finished strip steel.The cross shaft universal coupling is an important part of the transmission torque in the main transmission system.The high efficiency and stability of the crossshaft and fork head of the universal joint parts ensure the quality and productivity of the finished strip steel.In the actual production environment,the main drive system usually suffers from impact load and long-term work.The main research direction of this paper is that the crossshaft and fork head experience wear → early crack → crack propagation → part fracture failure process.The crack initiation position and crack growth process of cross shaft and fork head in production are the main research directions in this paper.This paper mainly completes the following work:(1)The structure and kinematics analysis of the cross shaft universal coupling are studied.The conditions of the constant speed transmission are discussed.The results provide the basis for the modeling and Simulation of the transmission system.Solid modeling of transmission system is carried out by Solid Works to complete interference inspection.The rolling force and rolling torque are deduced by the parameters of rolling products.When the model is introduced into Adams,the rolling force is applied at the roll end,the motor end is applied with the boundary conditions such as the speed and torque.Finally,the output torque of the roller end is compared with the rolling torque of a factory,and a transmission system model is established.(2)The 3D simplified model of transmission system is introduced into ANSYS Workbench:the material setting,mesh division,constraint and load are used to analyze the key parts fork and cross shaft;Considering the influence of low-order mode on torsional vibration system in actual production,the mode analysis of transmission system is carried out to obtain the low-order mode diagram and the natural frequency of each mode.From the above two points,it is concluded that the motor end universal joint is easy to damage,so the motor end universal joint is the key research object,and it is prepared for the crack and crack growth of the key parts.(3)The stress diagram of the crosshead and crosshead is obtained by introducing the cross shaft and fork head of the motor end into ABAQUS,and the stress diagram of the crossshaft and fork is obtained.In FRANC3 D,the crack size,material coefficient related to crack growth and the required criterion for crack growth are set,Finally,the equivalent stress intensity factor and aN curve of each crack growth are obtained.The above research shows that the crossshaft and fork head are dangerous positions.When cracks appear in the crossshaft and fork head,the fork head is prior to the cross shaft fatigue fracture,and the fracture period of the fork head is three times faster than that of the cross shaft.In actual production,the fork head can be monitored in order to avoid accidents.