Research On Fine Straightening Model In Plate And Strip Straightening Process

Sheet and strip straightening machine is one of the important auxiliary equipment after sheet and strip rolling.It is mainly used to improve the flatness of sheet and strip and the mechanical properties of the material.The principle of straightening lies in the continuous bending of the material.The straightening machine continuously bends the material to produce elastoplasticity.Deformation causes the longitudinal fiber layers to become equal and flattened.At present,there is still a gap between the calculation of process parameters such as intermesh and bending curvature in the straightening theory and the actual situation.The main reason is that most straightening models focus on the research of hypothetical and idealized straightening processes.There are more qualitative analysis and less quantitative analysis.On the other hand,many straightening problems in actual production have not been paid attention to,such as the phenomenon that the bending curvature radius is smaller than the work roll radius during the straightening process,the maximum bending amount of the rolling stock exceeds the intermesh value,etc.Hence the need to combine technical and practical problems straightening theoretical analysis,a lot of straightening experimental research to advance the development process of straightening model refinement to make accurately applied to actual production to meet the high quality and strip flatness requirements.This paper uses the laboratory 11-95/100-1200 roller straightening experimental platform to study the deformation mechanism of plate and strip from the theoretical,experimental and simulation aspects,and establishes a refined straightening model.The relationship and law between the process parameters in the bending theory which are commonly involved in roll straighteners and stretch bending straighteners are discussed.The pressure roller device has been improved to ensure the stability of tension.The main research contents and results of this article are as follows:1.Considering the work hardening phenomenon of plate and strip,the stressstrain behavior during the continuous bending process of plate and strip is analyzed,and the difference between its elastic recovery behavior and ideal elastic plastic plate and strip is discussed.2.A 1060 aluminum plate(length × width × thickness: 650 mm × 80 mm × 4.8mm)was used as the research object to perform a straightening experiment,and the bending deformation of aluminum plates with different intermeshes was analyzed in detail.The influence of the intermesh on the maximum bending position of the sheet,the contact point between the sheet and the straightening roller,and the contact angle are discussed.The relationship between the bending curvature and the intermesh and the change law of the minimum bending curvature radius are analyzed.3.Established a finite element model of 1060 aluminum,Q235 and Q345 plates straightened on an 11-roller leveler.Based on the agreement with the experimental data,the relationship between the maximum bending amount of the plate,the cross-section stress,the maximum bending curvature and the intermesh was studied.And according to the change law of the difference between the maximum bending amount and the intermesh,suggestions for setting the reduction amount are given.4.Aiming at the problem of tension instability caused by the change of friction coefficient on the surface of the tension roller during the straightening of the strip,by changing the wrap angle to compensate for the tension loss caused by the decrease of the friction coefficient.An optimization model with tension as the objective function and pressure roller movement trajectory as the constraint function was established.The pressure roller device was improved and a new pressure roller mechanism was designed.Through theoretical,experimental and numerical simulations,this paper studies the relationship between the reduction and the maximum bending amount,bending curvature,stress and other parameters,and establishes a straightening model that is closer to the actual production.The main factors affecting the stability of tension were studied,a stable tension control model was established,and a new pressure roller device was proposed.The work done has helped to enrich and improve the theory of straightening.