Research On The Running Stability Of Oil Film Bearing In Wire Rod Mill

As oil-film bearing is developing in the direction of large scale, heavy load, high speed, continuation and automation, the operating stability of mill oil-film bearing oil is becoming more and more important. The operating stability of oil-film bearing directly determines the property of friction and wear of oil-film bearing, and determines the quality of rolling element. In the process of practical rolling, perturbation on the displacement and velocity of the roller, as well as the fluctuation of rolling force, feeding oil pressure and feeding oil temperature, will have an influence on the operating stability of oil-film bearing. Therefore, the quality of rolling piece and the operating performance of oil-film bearing will be influenced.In order to study the operating stability of wire mill oil-film bearing, this study is based on the large-scale comprehensive test rig of oil-film bearing and supported by Natural Science Foundation of China(51205269), Science Foundation of Shanxi province(2012011018-2) and Science Foundation for returned overseas Chinese(2013-093). In this paper, mathematical model for analyzing the operating stability of oil-film bearing is built and stable operating condition was analyzed theoretically. At same time, a test bearing used for testing oil-film parameters is designed and then the operating stability can be analyzed in experiment. Furthermore, based on the data from the experiment and the methods of grey relational analysis and analytical hierarchy process, the impact factors influencing the operating stability of oil film were calculated and analyzed.The main content of this study is as below.(1) The development and application of oil-film bearing was briefly introduced. And the necessity and importance of studying the operating stability of oil-film bearing was clarified as well.(2) The mathematical model was built for analyzing the operating stability of oil-film bearing. Combining the oil lubricating theory and rotor-bearing dynamics, discriminant model was built and kinematic equation of rotor center is deduced.(3) The theoretical equation with numerical solving method of Fortran language was solved based on oil-film stiffness and damping, and critical mass of rotor-bearing system was obtained. Then the operating stability is analyzed linearly. Meanwhile, the trajectory of rotor center with different structure parameters, different rotational speed and different rolling load is solved. Then operating stability of oil-film bearing is analyzed non-linearly.(4) Based on the present test rig of oil-film bearing, new test bearing used for testing oil-film parameters is designed and its strength is checked. The thermocouples, pressure sensors and eddy current sensors installed on the inner surface of the test bearing is respectively used to monitor and collect the oil-film temperature, oil-film pressure, oil-film thickness and center trajectory of roller.(5) Analysis on impact factors of operating stability of oil-film bearing was done. Based on the methods of grey relational analysis and hierarchy analysis, the impact factors of operating stability were calculated. Thus it will provide some references for reasonably choosing and adjusting the operating loadcases.