Study On Roll Profile And Process Parameters Of Two Roller Straightening Machine Of Large Diameter Bar

In recent years,continuous casting technology of alloy Steel and large rolling mill have been applied to the production of large diameter bars.Consequently,forging production is gradually replaced by rolling technology as the primary method of production for bars whose diameter is less than 200 mm,which greatly reduced the cost of production.As the last finishing process,straightening plays a significant role on the final quality of bars.Two roller straightening machine has the advantages of simple structure,high precision and unique feature that the whole bar can be processed.The application of two roller straightening machine can significantly bring a high yield of good steel.More and more attention has been paid to this machine.In recent time,most of domestic researches about two-roller straightening are concentrated in small and medium specification.The theoretical research about two-roller straightening machine of large diameter bars has important practical significance.Based on the elastic-plastic theory of metal material,the relationship between stress and strain,variation of the curvature of rods in straightening process was studied.In consideration of material strengthening characteristics,the curvature ratio equation of bar straightening was summarized.The key factors to determine the residual curvature of the bar was confirmed.According to the principle that bar is bent and straightened in the process of straightening,concave and convex straightening rollers for large diameter bars were designed.Afterwards,straightening process was simulated by finite element software ABAQUS.Starting with the contact condition between the bar and rollers,the straightening roll length was modified.The straightening quality is obviously improved under the condition of new roller profile.Finally,on the basis of certain roller profile,the optimal parameters of different specification bars were determined through the analysis of post-process results of different bars in a series of straightening process parameters.By fitting the curve about the relationship between straightening process parameters and rod diameter,the formulas are calculated.In addition,the reliability of formulas is verified.Those formulas can be used for a reference in actual production.