Reasearch On Production Mechanism And Test Of Chatter Mark On Roller Surface For Cold-roll Temper Rolling Mill

Automotive industry is supporting industry in those countries with advanced industry. More and more requirement focused on quality and variety of automobile leaf-spring, thus result in iron and steel production enterprise continuously reform technic and improve quality. Temper rolling mill a kind of cold rolling mill with small quantity of reduction, it is used in production technology process of automobile leaf-spring. Sometimes doubtful vibration occured when temper rolling mill runs with high speed. In one cold rolling plant, light and shade chatter mark appeared on the surface of back-up roll of the temper rolling mill after a period of usage, the chatter mark may be impressed on the surface of strip steel, thus severely affected production efficiency and surface quality of strip steel. Solving problem of temper rolling mill vibration is an important subject faced during the course of improve quality of domestic strip steel.The studying work of this dissertation is based on the theory of rolling, linear vibrations, nonlinear vibrations, diagnosis of vibrations, friction and lubrition in rolling, the temper rolling mill was regarded as research object, the following studying work was proceeded in the dissertation:(1) The dynamic model of torsional vibration is created, the equivalent mass and the equivalent rigidity of the model elements are obtained. Using lumped mass method and finite element method to calculate the nature characteristic of the model, the results calculated by the above two methods also be compared. Modal flexibility and energy distribution of tortional vibration system are calculated and analyzed. Torque amplified factor of each shaft is calculated under condition of damping and undamping, thus verified the dynamic character of torsional vibration system.(2) The dynamic model of vertical vibration is created, the equivalent mass and equivalent rigidity of the model elements are obtained. Using lumped mass method and finite element method to calculate the nature characteristic of the model, the results calculated by the above two methods also be compared. Modal flexibility and energy distribution of vertical vibration system are calculated and analyzed. Based on the analysis results, resonable suggestion about dynamic optimum design of temper rolling mill's vertical vibration is proposed.(3) The horizonal equation and the horizonal dynamic model of temper rolling mill's working roll are created, vibrate simulation and stability analysis of the model are proceeded, the reason which caused negative damping of the rolling interface is analyzed. The character of horizonal friction self-excited vibration caused by negative damping is described through phase picture, Poincare section, maximum Lyapunov exponent, et, al. According to the influence of horizonal and vertical movement of the working roll, the dynamic model and mathematic model of the top roll system modal coupling vibration system are created, the conclusion of working roll's self-excited vibration caused by the effect of rolling interface dynamic friction and modal coupling is drawn through numerical simulation.(4) Combined with working roll's horizonal dynamic model and oil film thickness model at the entrance of rolling deform area, the mathematic model of temper rolling mill's rolling force and dynamic rigidity change with working roll's horizonal chatter velocity is created. The conclusion of coupling relationship among horizonal chatter velocity, rolling interface and vertical dynamic rigidity is drawn. According to the above mathematic model and vertical dynamic model of the temper rolling mill, the simulate result shows that the coupling relationship result in self-excited vibration of temper rolling mill's vertical vibrate system, and therefore influenced generation of chatter mark on the surface of strip steel.Based on the above studying results and combined with the analysis result of the local testing signal, the correction of temper rolling mill's vibration mechanics which analyzed in the frontal chapters is validated, all of these provide theoretics guide for restraining chatter mark and vibration of temper rolling mill in production field. According to the production mechanism of chatter mark, technics measures are put forward to restrain vibration at the same time, practise result shows that these measures take good effect on restraining chatter mark on the surface of strip steel.