Research On The Setting Roundness Process By Three Follers

All the natural gad and more than85percent of the petroleum in the world rely steelpipeline transportation. Since the Qingdao oil pipeline explosion accident happened. Thecommunity proposed higher requirements for steel pipe quality. Competition betweenenterprises is increasingly fierce. The only way to survival and development of enterprisesis to improve the quality of products.According to the American Association of API standard, Ovality of large longitudinalwelded pipe should not exceed1%of its nominal diameter. Pipe production process andmaterial properties fluctuations could cause the ovality exceed standard. This will bringgreat security risks to pipeline. The widely used expanding,compression and over-bendingsetting round process, can only rounding the end of the pipe. Due to the unevendistribution of stress along the pipe axis, or long-term placement or use may cause ovalityincreasing.Inspired by the three-roll veneer reeling process, a new process called three rollerssetting round process was proposed. Through improve the technology and equipment onthe original device, setting round work can achieved along the entire pipe axis. It has avery important role to improve the precision of the pipe size.Based on springback theory of small curvature plane bending, and reciprocatingcurvature unity theory, This article will focus on the study for three rolls setting roundprocess. Because the tube subjected to pure bending, the circumference unchanged duringthe three rollers setting round process. The deformation of the tube are the same whether itis oval or round tube under the same loading parameters.Along the tube section there aretwo positive bending deformation zone and two anti bending deformation zone. Afterrepeated loading and unloading, achieve the unity of curvature finally.This paper mainly use finite element numerical simulation analyze the deformationlaw in the setting round process and the relationship between process parameters and theset round force.Three kinds of technology program were proposed for difference unloading processes in this paper. Found the best one through comparative analysis, then optimize theunloading process. Finally, the three rolls setting round rule founded in this paper wasverified by experiments.Three rolls setting round process can effectively rectify the ovality for the entire pipe,and effectively improve the distribution of residual stress.