بررسي، تحليل و عيب يابي ماشين چرخش ورق در واحد نورد سرد پيوسته

چكيده انگليسي :

Investigative Study and Analysis on the Performance of Twist Roll Machine in Continuous Cold Rolling Mill Mostashfi A a mostashfi@me iut ac ir Submitted on March 12 2011 Department of Mechanical Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi Supervisors M Kadkhodaei Assist Prof Email address kadkhodaei@cc iut ac ir Abstract Mobarakeh Steel Complex M S Co extended its production lines in the year 2000 to increase the production rate In many lines old systems were matched with the new ones However in some others there were some difficulties working old machines together with the new ones to overcome which specific plans were necessary Nevertheless there exist some machines with serious challenges in the course of operation One of these is twist roll machine TRM in the 5 stand tandem mill which is used to rotate the sheet to 90 degree Serious deficiencies including high wear rate of the machine rollers and increase in the maintenance expenses occur due to prolonged contact of the rollers with the sheets After all the most important problem is formation of marked defects on the sheet leading to low quality of the sheet surface at exit from the rolling mill In this project we first study the defects created by the machine as well as the influence of which on the product quality Several pin on disc wear tests were carried out on rollers to determine the wear rate as well as the friction coefficient of contact with St12 and to study the variations of which with changes in speed and the applied force The results were obtained for two different polyethylene rollers to investigate the effect of material on the wear parameters The machine geometry and conditions of contact between the sheet and the rollers were further studied by modeling the whole system in CATIA Accordingly practical suggestions to minimize deficiencies due to the quality of contacts with different rollers were proposed To analyze the contact forces as well as stress distribution throughout the sheet finite element simulations were done in ABAQUS for different operational conditions in terms of the sheet width and speed and the bridle rolls tension Distribution of wear along selected rollers was determined by measuring diameter at different sections and the results were compared with finite element predictions according to the distribution of stress along each roller and the relation between the contact force and wear rate obtained in the wear tests Moreover proper amount of the bridle rolls tension to prevent local plastic deformations and hence formation of marked defects on the sheet was determined for different operational conditions Finally to more effectively reduce the rollers wear rate a new arrangement was suggested for machine roll series Finite element simulation shows that this arrangement can lead to more uniformly distributed force on the rollers leading to reduction in TRM defects Key words Twist Roll Machine Wear Roller Continuous Cold Rolling Mill

مستشفي، امير

بررسي، تحليل و عيب يابي ماشين چرخش ورق در واحد نورد سرد پيوسته

سايش , غلتك