Experiments And Simulation Of Rolled Profile Strip With Variable Thicknesses In Lateral Directionin Through Bending Spreading Rolling Method

Under the background of energy saving and emission reduction,in order to reduce the quality of components and improve the carrying capacity of products,the concept of blank with variable thickness has been introduced in the industry.Blank with variable thickness has different thicknesses in different regions.Rolled profile strip with variable thicknesses in lateral directionin is a kind of blank with variable thickness with different thickness distribution in the width direction of the blank At present,the preparation methods of rolled profile strip with variable thicknesses in lateral directionin are tailor-welding,strip profile rolling,and point-symmetrical rolling.The product performance of the tailor-welding method is influenced by weld and thickness mutation.Because of the uneven longitudinal flow of metal,the products of strip profile rolling method are easy to produce wave shape,torsion and other defects.In the point-symmetrical rolling method,problems such as sliding dislocation occur between blanks.In order to prepare large thickness ratio(1:2)rolled profile strip with variable thicknesses in lateral directionin,this article starts from three aspects:roll design,finite element simulation,and experimental verification,a three-dimensional rolling model suitable for bending spreading rolling method to prepare rolled profile strip with variable thicknesses in lateral directionin was established,the influence of core process parameters such as tension,the number of rolling passes,and the roll diameter on the experimental results of rolled profile strip with variable thicknesses in lateral directionin by the bending spreading rolling method was analyzed,the preparation of rolled profile strip with variable thicknesses in lateral directionin with a large thickness ratio of 1:2 was studied.The main results are as follows:(1)The finite element model suitable for the bending spreading rolling method is established,and the accuracy of the model is verified through experiments,which provides a reliable predictive tool for the design of rolled profile strip with variable thicknesses in lateral directionin.(2)Combined with the experiments and the finite element simulations,the influence of core process parameters such as tension,number of rolling passes,and roll diameter values on the rolling results of bending spreading rolling method was studied.The tension increased from 1500N to 2500N,the rolling force decreased by 18.6%,the longitudinal flow of metal increased by 21.4%,the thickness of the blank decreased by 2.5%,and the lateral narrowing of the blank increased by 4.3%;the number of rolling passes increased by 3 to 5,no significant change in rolling force and metal longitudinal flow,the deviation between the thickness of the straight end of the blank thin area and the ideal value decreased from 18.1%to 1.9%,and the lateral narrowing of the blank increased by 36.4%;roll diameter increased from 120 mm to 360 mm,the rolling force increased by 123.1%,the longitudinal flow of the metal increased by 76.5%,the blank thickness reduced by 1.2%,and the lateral narrowing of the blank increased by 27.7%.(3)A U-shaped bending spreading rolling method was proposed,and a U-shaped roller is designed for the preparation of large thickness ratio(1:2)rolled profile strip with variable thicknesses in lateral directionin.The innovative points of U-shaped roll design:the symmetrical design of the force can eliminate the problem of roll transverse movement caused by the huge transverse force during the rolling process,and ensure the realization of the large thickness ratio(1:2);the thin area is only designed in a straight line segment,which reduces uneven degree of metal longitudinal flow by 68.6%,and effectively avoids the occurrence of wave-shaped defects.The new processes include:bending thinning rolling;flatting rolling;finishing rolling.(4)The rolling experiments of the U-shaped bending spreading rolling method were designed,and a large thickness ratio(1:2)rolled profile strip with variable thicknesses in lateral directionin prototype was successfully prepared,which verified the feasibility of the U-shaped bending spreading rolling method.The thickness of the prototype thick area is 2 mm,the thickness of the thin area is 1 mm,the thickness ratio is 1:2.The length of the thin area on one side of the blank is 7.7 mm,compared with the hole value of 7.93 mm,the error is only 2.9%.