The Study On The Influence Factors Of Critical Pre-tightened Force Of Ower Beam With Composite Structure

Due to the restrictions of the casting process, equipment conditions, transportationsand installation conditions, the beams of large forging hydraulic press usually requiressome separate blocks, the beams use some preload bolts make three or four pieces ofcasting beam body assembled. So how to accurately calculate and impose the preload willbecome the crucial problems in the whole design process of the hydraulic press. In thetraditional calculation and checking, the beam often be simplified to the bean section orvariable cross-section to get the bending stress and deflection in pure bending theory ofthe material mechanics. But it will bring some errors in this way of ignoring the shearstress and deformation for deep beams and can not meet the accuracy requirement inengineering design.This paper mainly aimed at the influence factors and calculation method of thecritical pre-tightened force of the composite lower beam of large forging hydraulic press,it analyzed the shortage of pure bending theory of the material mechanics in solving thelower beam stress by the numerical simulation, and should be make the lower beam as thedeep beam, considering the influence of the ratio of span and height to the bending stressand deformation, finally got the size and distribution of the bending stress, the range of theratio of span and height for using material mechanics formula solution. Secondly, itcontrasted and researched the load condition, eccentricity and ratio of span and height howto influence the structure integrity, and found the main impact regulars, generalized thepreliminary calculation of the critical pre-tightened force.This article designed the lower beam of composite structure with five different ratioof span and height, and tested the formula of critical pre-tightened force in two loadconditions by electrical measurement method. The results showed that numericalsimulation and experimental results were in good agreement, this indicates that thenumerical simulation results have some reliability, and the formula of criticalpre-tightened force have a certain reference value.