Study On Multi-cycle Rolling Technology Of Automobile Leaf Spring With Variable Section

In recent years,automobile production and sales in our country showed explosive growth.In the context of energy saving and emission reduction,vehicle lightweighting has become a mainstream direction of vehicle design and component optimization.The application of variable cross-section automotive leaf springs is more and more widely used.However,due to the problems such as the low yield of the existing technology and the low production efficiency,the cost is high,which has always restricted its application.On the other hand,the theory of variable gauge rolling is much more complicated than the simple rolling,and its development time is short and needs to be further enriched and improved.Based on the practical application,this paper improves the existing rolling technology of variable cross-section automobile leaf springs and improves the theory of variable gauge rolling.The feasibility of the new technology and the reliability of variable gauge rolling control models are verified through experiments.The main progresses are as follows:1)Improving the existing rolling process.Aiming at solving the problem of large cutting loss and complicated manufacturing process in the existing rolling process,a more material-efficient and multi-cycle rolling process was proposed.The transformation effect of the multi-cycle rolling process was analyzed in an example of two-cycle rolling process.After the transformation,the productivity of labor increased by 46.8%,the cutting loss by 50%and the annual economic benefit of each rolling mill increased by 2.39 million yuan.2)Developing the multi-cycle rolling process specific process.The cross-sectional shape,cross-sectional dimension and heating process of variable cross-section automotive leaf spring blanks were designed.The rolling process,rolling speed and rolling tension of variable gauge rolling were defined.Taking the two-cycle rolling process as an example,dimension calculation of equipment was completed,and the new technology layout of the equipment was given.3)Improving the variable gauge rolling theory.In view of the rolling force calculation,the thickness control,the rolling length calculation and the wide spread control in the variable gauge rolling,a series of accurate calculation and control models were established considering the actual influencing factors and rolled piece's stress condition.4)Verifying the feasibility of multi-cycle rolling process.Using the existing equipment of a spring plant,the two-cycle rolling test of the small-size variable cross-section automotive leaf spring with No.2912010-D5041 was successfully carried out,which proved the feasibility of the new process.5)Verifying the reliability of variable gauge rolling control models.Laboratory rolling experiment showed that the calculation of rolling force,the control model of thickness and the calculation of rolling length were of high reliability.The maximum error in rolling force was 9.3%,the error in maximum thickness was 8.7%,and the error in the length was less than 2mm.At the same time,some laws of variable gauge rolling were also found.When the exit thickness is the same,the rolling force of the upward rolling is smaller than that of the downward rolling.When the other conditions are the same,the spread of the downward rolling is less than that of the upward rolling.Finite element simulation results showed that the idea of wide spread control by tension was feasible and the reference value of tension setting was obtained.