Short Stress Path High Rigidity Rolling Mill Dynamics Analysis And Simulation

Short stress path rolling mill was very popular among bar mills, and widely used in the production line of profile steel, narrow strip steel and non-ferrous strip steel. In rolling hot narrow strip steel, it was not only enduring much more rolling force and moment, but also suffering dynamic loading. Dynamic characteristics directly acted on narrow strip steel and influenced its dimensional precision and surface quality. Short stress path rolling mill was used in the front of the finishing mill group by rolling300mm-width narrow strip steel and used as the object of study, and its dynamic characteristics were researched. After reading dynamic papers on rolling mill and theory about rolling thickness, dynamic analysis in the vertical direction which was closely related to the thickness of the strip and simulation were conducted. Conducting dynamic analysis and simulation could contribute to enhancing dimensional precision of the strip, ruling the craft of hot rolling and designing new roll mill, it was very useful and meaningful in academic and production. The main content of this paper are as follows:First, dynamic analysis was conducted. According to the characteristic of the structural, four degree of freedom vibrating system was created in the vertical direction. Then differential equations of motion were listed and solved. From the calculation, resonance could happen around the first three order of frequency. Under the second order of frequency’s (182.87Hz) simulation, the system would vibrate and create deviation in dimensional precision.Second, the inherent characteristic of the major parts was analysed. The following was found from the major parts’modal and harmony analysis using ANSYS. The rigidity of the bearing pedestal was strong enough that it wouldn’t cause fluctuation of the strip’s thickness. The weakness of the roller which was directly contacting strip is at the two ends, and under bearing support, the radial displacement response to the mid-frequency was big, the harmonic response also reflected the phenomenon. So the rigid rollers was replaced with its modal neutral files after building the virtual prototype in ADAMS.Third, Simulation was done in the vertical direction with the whole mechanism. Under the vibration module, simulation was conducted, considering influence from parameters such as strip’s wideness, bearing pedestal’s simulation, rolling force, system’s damping and stiffness. It was found that the displacement response to the mid frequency around200Hz and400Hz was so big, and simulation caused by rolling should be avoided. To reduce the displacement response to the low frequency, the following measures could be possible. In designing new short stress path rolling mill for producing narrow strip steel, appropriate damper should be adopted in balance device and enhance the stiffness between the draw bar and bearing pedestal as much as possible. In drawing up the craft of hot rolling300mm-wideness strip, shorter and thicker roller should be adopted and appropriate rolling reduction in vertical direction should be distributed to reduce rolling force. In daily maintenance, inspection and lubrication should be intensified to avoid causing simulating force to the roller.