Research On Main Stretching Process Of Crankshaft For Slab Sizing Press

Large forgings are often used as the core parts of large scale equipment and their quality directly affect the safe and stable operation of the equipment.These forgings are made of ingots directly.Owing to both Physical and chemical properties of metal material,there are inevitably shrinkage cavities,porosity and segregation in ingots,and these defects must be eliminated by reasonable forging process.Therefore,the forging process of large forgings is an important link to ensure the quality of forgings.The reasonable forging technology can not only guarantee the internal quality of the forging,but also save the material,reduce the forging process and meet the dimensions requirement of the forging.This paper is aimed at the quality and dimension requirements of crankshaft for slab sizing press,to study its main stretching technology.Firstly,the single-pass compression experiment was done by Gleeble-3800 thermal mechanical simulator.Under different deformation temperature between 850-1 050? and strain rates between 0.1-10,the deformation resistance of the testing steel was measured.Meanwhile,linear regression is applied to obtain the testing steel's Arrhenius equation and Z-Hollomen parameter equation,and the mathematical model of high temperature deformation resistance was established on those two equations.The model shows that the calculation results are in good agreement with the experimental results,which can provide mathematical model for forging process simulation.Secondly,according to the structural characteristics of crankshaft,the forging process of crankshaft is made,and Aim at the problem of accurate calculation of spreading,the four factors which affect the spreading volume calculation,such as the tool width ratio,the blank width ratio,the reduction ratio and the friction factor,are analyzed and compared by using the orthogonal experiment method.Finally it is found that the two most influential factors are the tool width ratio and the blank width ratio,at the same time,the changing regularity of spreading is analyzed under the single factor,such as the tool width ratio and the blank width ratio,and lastly,based on the above analysis,the empirical formula of spreading volume calculation is optimized to improve the accuracy of the spreading volume calculation.Finally,with the optimized spreading volume calculation as the basis,the main stretching process is optimized by using the method of random direction.The material model of 30Cr2Ni2 Mo steel is made in DEFORM software,and the simulation of the main stretching process for the crankshaft is carried out,at the same time,the temperature field,stress field and strain filed of the main stretching process were analyzed,and the final size of the billet was verified,the rationality of technology and the accuracy of optimization formula for the width calculation was proved.