Study On Optimization Of Pass Weld Mode For Temper Mill Of Continuous Annealing Line

Under the background of the gradual decrease of petroleum energy,the task of building a resource-saving and environment-friendly society has become a top priority.As an important industry that consumes petroleum resources,the consumption of petroleum is proportional to the weight of the automobile.Besides meeting certain anti-collision performance,lightweight and energy-saving automobile industry has become the trend of development.BH steel is widely used in the production of automotive panels because of its good strength and dent resistance.However,when BH steel passes through the flattening machine of the continuous strip mill,the elongation of the strip varies greatly when it passes through the weld,which makes the performance of the head and tail of the strip more inconsistent with the length,the shear amount of the product is too much,and the yield rate is low.On the other hand,the mechanical properties of the BH steel are also inconsistent because of the improper setting of the hot rolling and continuous strip production process.Production regulations bring great economic losses to enterprises.For this reason,this paper takes the continuous annealing unit as the research object,studies the inconsistency between the tensile strength and yield strength of BH steel and the excessive length of elongation fluctuation.The main research contents are as follows:(1)The physical mechanism principle of BH steel is analyzed,and the reasons for its high strength and depression resistance are revealed.Secondly,from the perspective of the influence of chemical composition on the properties of BH steel,it is concluded that different chemical elements have different effects on the mechanical properties of BH steel.Then,it is divided into hot rolling process,annealing process and tempering process.The influence of different process parameters on mechanical properties of BH steel in different process sections is analyzed.Finally,according to the actual production situation on site,the current situation of leveling through weld and the influencing factors of elongation fluctuation are analyzed.(2)In view of the inconsistency between the yield strength of BH steel and the excessive length of elongation fluctuation in the process of smoothing through the weld,combined with the equipment and structure characteristics of the continuous retreat unit,from the point of view of the continuous annealing process,through optimizing the annealing temperature and the annealing speed of the strip,the inconsistency of the yield strength of BH steel can be controlled.(3)In order to further improve the quality stability of BH steel products,a friction coefficient model and an elongation prediction model are established based on the setting of small tension and large rolling force parameters.The elongation is compensated in the actual production process to reduce the fluctuation length of elongation.The "AL" mode can reduce the elongation discrepancy of the weld and improve the yield of the product.(4)The optimization measures of over weld mode of temper mill of continuous annealing unit are applied to the actual production site of strip steel to analyze the effect.From the actual situation on site,it is concluded that the elongation fluctuation length and shape quality of BH steel have been greatly improved,and the yield strength discrepancy of tensile strength has been significantly reduced.It has created great economic benefits for the site,and has the value of further popularization and application.