Study On Straightening Model And Technology Of The Head And The Tail Of The Plate

Straightening is one of the key processes of medium production,which directly determines the shape and residual stress and other quality indicators of products.In the process of plate straightening,because of the phenomenon of equipment jumping,uneven temperature and uneven thickness in the straightening of the head and tail,the shape defects of the head and tail are prominent.This problem has always been the difficulty of the straightening process.In this paper,taking the mathematical model of curvature integral as the breakthrough point,the parameters of plate straightening are the emphases for research.At the same time,the head and tail straightening model is put forward and verified by experiments.The main contents of this paper are as follows:(1)The curvature integral mathematical method is used to study the straightening theory.The curvature integral core equation is converted into the equations of ratio of reverse bending rate or the curvature difference integral iteration to be solved,and the corresponding solution flow chart is established.(2)The influence of different straightening parameters on the straightening process is studied by using the curvature integral straightening model,and the effects of temperature,thickness and pressure on the reverse bending rate,contact angle,bending moment,straightening force and plastic layer coefficient are discussed;It is found that the reverse bending rate and the contact angle become larger with the increase of the pressure;With the higher of the temperature,the smaller the bending moment and straightening force of the plate with the same roll number,but the increase of the thickness and the pressure will cause the increase of the bending moment and the straightening force;the effect of rolling reduction ?thickness and temperature on the coefficient of plastic layer have the same reaction trend that the plastic layer coefficient increases with the increase of temperature,thickness and rolling reduction.(3)In consideration of the actual production,there is a overpressurephenomenon in the straightening of the head and tail of the plate due to the bouncing of the equipment and the press down.The straightening model of the head and tail of the plate and the optimal flow chart of the different plate straightening are established.As an example of the straightening process of a11-roller straightening machine with a plate thickness of h=20mm and a plate wide 3000 mm,the optimal reduction and the optimal ratio of reverse bending ratio at different temperatures are studied.(4)The 11-roller plate straightening machine is used as the experimental object to verify the head and tail straightening model.The experimental results show that the difference between the straightening force and the measured value is less than 5% by the curvature integral model,and the residual curvature of the head,the middle and the tail of the plate is calculated by the measurement of the unevenness,and the residual curvature theory is calculated.There is a good unity between the calculated values and the actual measured values.