Study On The Straightening Model Of Very Thin Stainless Steel Strips

With the rapid development of the domestic information and communication industry and micro manufacturing and other industries,the plate quality of extremely thin stainless steel strips has put forward increasingly high requirements.Therefore,how to improve the manufacturer’s stainless steel extremely thin strip plate quality is an urgent task.At present,the production site is mainly through the role of stretching and bending,so that the strip produces elastic-plastic extension deformation,to eliminate plate defects and improve the quality of the strip.However,because the elasto-plastic deformation of the stretch-bend straightening process is very complex,the relevant theoretical basis is relatively weak,where there are too many hypothetical conditions and it is too idealized.This can lead to low efficiency of parameters setting in extremely thin strip stretch-bend straightening process tension,where the relationship among stretching force,bending volume and elongation rate has been established on empirical data for a long time.The research object of this paper is a stretch-bend straightening machine in a domestic stainless steel extremely thin strip mill.Based on the theoretical study,the mathematical model between tension,bending volume and elongation of the extremely thin strip in tension bending and straightening is established through an experimental study which has been done by a self-developed test platform.The research work is presented as follows:(1)In response to the bending curvature equation derived from the flexural properties of beams in material mechanics,there is a problem of large error between the theoretical calculated value and the experimental test measurement value.In this paper,the strip curve in the bending unit is assumed to be a parabola.The calculation formula of the relationship among the tangential angle of the strip,the tension and the compression-bending amount is obtained.Then the curvature calculation method is optimized,and a mathematical model which can accurately describes the relationship among tension,compression-bending amount and bending curvature of very thin strips is established.(2)The linear strengthening nature of the strip is studied.Based on the deflection mechanism of the neutral layer in the tensile bending process,the final elongation model of the elastic recovery of the strip after tensile bending is established,and the coupling relationship between tension,press bending amount and elongation is obtained.(3)We conduct the bending curvature test experiments of 304 extremely thin stainless steel strip(length x width x thickness: 320 mmx30 mmx0.1 mm)in our research group’s self-developed tensile bending experimental platform.Then we analyze the bending deformation under different tensions and press bending volume,and explore the relationship among bending curvature,tension and press bending volume.Ultimately,we validate the bending curvature calculation model.The results show that the error between calculated results obtained from the formula before optimization and test value is among 2.1% ～ 127.0%.The error between calculated results obtained from the formula after optimization and test value is among 2.3% ～ 21.6%.The maximum error of the optimized curvature calculation results is 105.4% smaller than the maximum error of the unoptimized formula calculation results.(4)The tension bending test of 304 very thin stainless steel strip(thickness of0.1 mm and 0.2 mm,respectively)are conducted to investigate the relationship between different tensions,press bending volume and elongation.The tensile bending test are also carried out to compare and analyze the calculation of the theoretical model and the test results.The results show that the error of the theoretical calculation is basically controlled within 10% when the tension ratio is greater than 0.05.