Design Optimization and Development of PQF Mill 238 mm Pass

In order to solve the problems of low wall thickness accuracy, high rates of pipe body pulled concave, hole and longitudinal internal damage of the light-wall gas vessel-service steel pipe, the FE simulation method is used to analyze the influence of pass parameters before and after the optimization on distribution of outlet wall thickness distribution of each pass of the section, the distributions of rolling stress and strain, and metal flow velocity of each point. Accordingly the pass parameters are optimized, including the height, the eccentricity, the groove radius, the connecting angle, and the roll gas, etc. The FEA results show that due to the above mentioned said optimization, the uneven metal deformation is improved, and the maximum equivalent stress reduce. Thanks to application of the said optimized design to the actual production of the light-wall gas vessel-service pipe, the roll wear becomes more uniform, the pipe wall thickness accuracy is improved, and the rate of the pulled-concave and hole defects reduced from 1.1‰ down to 0.21‰, and the that of the longitudinal inner damage defect from 12% down to 3.12%.