Study On The Influence Of The Slip In The Cold Rolling Process On The Torsional Vibration Of The Main Drive System

Metallurgy industry is a predominant impetus of national economy. As the main device of metallurgical production, steel rolling machine is developing with high speed, high load, continuum and large-scale. Characterized by high precision and thin strip steel, the cold tandem mill requirs a strick quality control of it’s products. At the same time, vibration caused by rolling mill can affect quality of products and can also affect or even destroy the machine itself. Slipping phenomenon which happens while rolling can affects the vibration of rolling mill, the main transmission system and also quality of strip.Cold rolling line of Hanbao cold tandem mill in Handan Iron and Steel Comapny offen encounters vibration while the machine operating with a high speed, because of it’s big rolling force, high rolling speed and thin rolling strip.This thesis takes vibration problem of cold tandem mill F4 unit as the research object, pointing at slipping phenomenon from the following aspects.(1)Establishing a 7 degrees of freedom torsional vibration of transmission system, which is based on the characteristics of the main drive system of cold tandem rolling mill. With MATLAB software, the principal mode and the natural frequency of F4 unit can be gained, besides, torsional vibration amplitude of every shaft segment of the main drive system while slipping can be got. The self-excited vibration model of the driving system of the cold tandem mill can also be established while slipping. After calculation, we can draw the conclusion that self-induced vibration is unstable.(2)After deep analyze of the causes and mechanism of slipping while biting and rolling, the influnce factors can be found out. Defining a rolling factor as the judging conditon of slipping and amend it when actual conditions are taken into account.(3)Simulating the rolling process by ANSYS/LS-DYNA software, the influence of rolling process on the strip is obtained. Obtaining rolling force variation curve and relative velocity variation curve of metal flow in deformation zone with different friction coefficient, reduction rate, rolling speed and tension. Based on this, the controllable measures for the skid are put forward.(4)Getting the safety factor on this unit of slip phenomenon after verifying the data of cold tandem mill F4 unit. The factors affecting the slippage factor were analyzed by the rolling process parameters of F4 unit, and trends of the factors affecting the change of the slippage factor were obtained. Through the working data, getting some relationship of the factors that have not been obtained according to the theoretical judgment. Finally according to the overall characteristics of the cold tandem mill, getting the feasible measure of the slip phenomenon of the F4 unit in actual working conditions, and the effect of the performance of the emulsion on the friction coefficient between the strip and the roll is analyzed. Adjusted the saponification value, PH value and the iron content of the emulsion, getting the best adjustable threshold to restrain occurrence of the slip phenomenon.