Research On The Carrying Capacity Of The Main Transmission System Of Four-high Plate Rolling Mill`

With the rapid development of the industrial technology, the rolling mill equipment continues melting towards maximization, high speed, automation and high-accuracy directions. Meanwhile, the huge dynamic load happens in the rolling procedure causes more trouble to the safe-production so that it results in great accidents and heavy loss occasionally. It is of great meaning to study the dynamic characteristics and carrying capacity of the main transmission system of the rolling mill for improving its production capacity, guaranteeing the safe production, and improving product quality. The R3 four-high milling roll of a heat belt iron plant was taken as the example in this dissertation, the carrying capacity of its main transmission system was studied.Combining the torsional vibration theory, both at home and abroad, of the main transmission system of the rolling mill, the thesis also researched the dynamic characteristic of the main transmission system of the R3 four-roller rolling mill, established the torsional vibration kinetic model and mathematic model of the system, and still made use of Matlab procedure having programmed and calculated the natural frequency, fundamental mode, dynamic response and the torque amplification factor(TAF). All the results accord with the field measurement.The torsional distortion and the torsional rigidity of the cross axle type universal shaft are calculated by using the three-dimensional finite elements method. And in this process the torsional rigidity of the cross axle type universal shaft was found having great impacts on the torsional vibration of the main transmission system. Based on this discovery this dissertation presented that the torsion rigidity of the cross axle type universal shaft must be taken into account when researching the main transmission system of the rolling mill.By applying the large-scale general finite element analytical software ANSYS, the main part of the cross axle type universal shaft was analyzed, the results shows that existing structures of the cross axle type universal shaft is unreasonable. And on this basis, through applying optimum design theory combined with the finite element analytical method, the universal shaft of the mill was restructured and promoted parameter scheme for the cross axle type universal shaft was presented.The dissertation also has full deep research into the influence produced by the gap between the palm end of the roller and its sleeve on the intensity and stress distribution of the cross axle type universal shaft joint roller end, the results indicate that the size of the gap between them had great impact on the intensity of the joint of the roller-ends. The gap is bigger, the stress is obvious larger. When the contact area decrease from 1/2 of the slot width (at this situation the scaleboard is almost contacting with the scaleboard slot completely) to 1/8 of the slot width (atthis situation there is only very narrow contact area between the scaleboard and the slot) the maximal equivalent stress increases 52.2%. The excessive gap is the main cause of the rupture destroys of the universal joint. The dissertation presents that the process of manufacture, assemble, the protection must be controlled strictly so as to ensure that the size of the gap does not excess the design value.The fruit of the research in this dissertation has been adopted by the heat belt iron plant. The reconstruct of the main transmission of the rolling mill according to the research result has greatly improved the carrying capacity of it and the accidents also have been decreased obviously. The research in the dissertation also has great reference value to the research of the main transmission system of the same kind rolling mill.