Study On Roller Shape Design Method And Straightening Parameters Of Steel Bar Two-roller Straightener

Straightening is an important process in the production of steel bars.Bar may inevitably become bending during heat rolling and heat treatment process,so it is necessary to use straightening machine to obtain straight bar.For bar straightening,the two-roller straightening method has unique advantages and has been widely used.This study Analyzes the problem of medium-and-large diameter steel bar’s poor straightening quality with two-roller straightener,and a high-precision concave roller suitable for Φ50~Φ70mm steel bar has been designed in this paper.This paper describes the mechanism of two-roller straightener and compares the different design methods of roller shape,then the three-section roller shape method has been chosen to design the concave of Φ50~Φ70mm steel bar.Considered the trend of the straightened bar’s curvature combined with straightening mechanism,the value of each section’s relative final curvature has been determined.And then,the designed concave shape can be calculated by MATLAB software.In order to prove the correctness of the concave roller designed,this study tests the straightening precision of 5 different diameter bar(Φ50mm,Φ55mm,Φ60mm,Φ65mm,Φ70mm),based on the parameters of straightness,ellipticity and surface roughness.The experiment results show that concave roller designed can ensure the high straightening precision of Φ50~Φ70mm steel bar.In addition,this paper has verified the straightening precision of Φ20mm and Φ30mm medium-and-small diameter steel bar.It has proved that the concave also has a strong versatility while ensuring the straightening precision of Φ50~Φ70mm bar.With the change of straightened diameter,the contact situation between the roller and bar will also change,which may affect the straightening results of different diameter bars.The two-roller installation angle parameter has been discussed in this paper,and the optimal installation angles of Φ50mm,Φ55mm,Φ60mm,Φ65mm and Φ70mm straightening bars,which are tested by straightening precision experiment,have been given.Furthermore,the principle of the selection of straightening speed and roller gap have been discussed,which can provide references for bar’s two-roller straightening.Finally,a GUI for two-roller straightener’s roller design has been developed of this paper.User just needs to input the basic parameters for straightening to obtain a variety of roller types,this executable program can save the designer’s calculation time and can facilitate the roller design.