Study On The Split Combination Pre-tightening Technology Of The Lower Beam In Heavy Forging Hydraulic Press

With the rapid development of nuclear power,petrochemical,ship and mannedspaceflight,the demand of large forgings have becoming more and more vigorous,which are usually forged on heavy forging hydraulic press.In order not to be restricted by other countries on the national economy and national security,we must have the ability to design and build heavy forging hydraulic press independently.It is an important symbol of the equipment manufacturing and an essential support to national defense.All of it has an important strategic significance.China First Heavy Industry had designed and manufactured a 100 MN free forging hydraulic press for a domestic factory.The whole machine adopts double column diagonal layout and multi-bolt preload frame structure.The maximum size of lower beam is about 10 meters,and it weighs more than 600 tons,which is considered as an over-long and over-weight parts.To solve the problem in casting,processing,hoisting and transportation of the lower beam,a split combination structure has been adopted,the two parts had been preloaded into a whole assembly by means of different bolts with different diameter on different positions.Supporting the appropriate pre-tightening force on the lower beam to ensure its integrity under typical loads became the key of the problem.In this paper,the lower beam of this press was taken as the research object,and the combination pre-tightening technology in different working conditions was studied emphatically.This paper focuses on the analysis of the two kinds of lower beam schemes between front-back split type and left-right split type.Take the split number of the lower beam,weight and size of the maximum body,and strength and stiffness of the lower beam as the main inspection indexes.Take the index of the integral lower beam as the base,through comparative analysis,the front-back split type is better in the split number,weight and size of the maximum body,and it's strength and stiffness index is closer to the integral lower beam.So it is more reasonable to adopt the front-back split type to the lower beam.In this paper,the structure of the lower beam was introduced briefly.The force analysis of the lower beam was carried out on three typical working conditions: center upsetting,eccentric upsetting and saddle forging.The calculation formulas of bending stress and deformation on three typical working conditions were listed,and the strength and rigidity of the lower beam were checked.With the aid of ANSYS Workbench,finite element analysismodel of two kinds of working conditions,such as center upsetting and saddle forging,were established.On the two working conditions,variation rules of bending stress and Z-direction deformation of the lower beam under different loads were analyzed respectively.A comparative analysis was performed between the finite element solution and the formula solution,so the application range of formula solution was obtained.On the two working conditions,the slit rule of the lower beam under different loads was analyzed respectively,and the critical non-slit load was obtained.In this paper,getting the best preload combination of the three bolts of the lower beam is the goal.Through the finite element analysis method,the relationship and influence rule between the preloads of the three bolts and the integral,between the preloads and Z-direction deformation of the lower beam were analyzed respectively on the two working conditions,such as center upsetting and saddle forging.Through the combination of theoretical analysis and numerical simulation,the deformation rule and slit rule of the lower beam on different external loading conditions were obtained.By using the orthogonal test method,the best combination of the three bolts preload was obtained by taking the integrity of the split combination structure as the criterion.On the condition of the best preload combination,the equipment has been well performed in the field trial operation and the process,which proved that the numerical research method and the result have great reliability,and it also provides certain references to determine the parameters of preload of the same kind of split combination equipments.