Research Of The Curve Of The Two-roll Straightener To Small Diameter Bar

With the progress of science and technology,the demand and quality for precision titanium bars has more higher requirements.However,titanium bars is resulted in varying degrees of bending and twisting through producing,transport,stacking and so on.They require being straightened by high-precision straightener before using.At present,the study of our country about small diameter(?3?15mm)titanium bar straightening is less,only some is about more straightening rollers,which can cause straightening zone empty and the waste of material.Although the two oblique roll straightener within the scope of the oblique roll straightener,it has a difference with others on the nature of works.The two oblique roll straightener mainly depends on the changing curvature of the straighting roll to straighten the bars.The two oblique roll straightener has no empty area and has high precision straightening,the wasting of the material can be avoided.Therefore,the study about the two oblique roll straightener for the small-diameter titanium bars has important theoretical and practical value.This paper describes the principle of the two-roller straightening machine.From the basic theory of elastic-plastic mechanics,we analyze the various curvatures and the stress,strain(deformation)during the process of the titanium bars being straightened.Introduce the three-curvature two-way anti-bending roll shape design methods and give the roll length,waist diameter,the rate of anti-bending,anti-bending radius and a series of parameters.By aided design software Auto CAD and 3D modeling software Pro/E establish the two-dimenshional and three dimenshional of the two oblique roll straightener.The curve of the introducing two oblique roll straightener is localization fitting studied through hyperbolic and three-roll-shaped curve,and comparative study found that the three-roll-shaped curve is more in line with the curve of the introducing two oblique roll straightener.At last the fitting equation of the introducing two oblique roll straightener is given.Straightening models of three-curvature anti-bending roll and introducing two oblique roll are set up in the Pro/E and analyzed in the LS-DYNA(display dynamics analysis)module of ANSYS.The stress and strain of different straightening stages are analyzed by simulation analysis.Analysis the change of the straightening force,guide forces born by the bar throughout the straightening process and residual stress of the bar after straightening.Give the mean to analysis the straightness of the straightened bar.By adjusting the angle of the rolls,analyze the impact of two different tilt angles of rolls on straightening quality at bars and find the best angle for bars of different specifications to be straightened,and comparative advantages and disadvantages of the two straightening rollers.Analysis the changes of the straightening parameters of different amount of depression.Finally,find the best parameters to straight bars of different specifications by the two kinds of two-roll straightening machine.