偏载对大型双柱预应力机架的影响

Influence of eccentric load on large double-column prestressed frame

针对双柱上推式锻造液压机,分析了在锻造过程中存在的偏载工况,研究了偏载的传递路径,明确了纵向偏载总是存在的客观性。建立了双柱预应力机架的力学模型,分析了在偏载作用下机架的受力状态。结合对机架工作过程的研究,确定了预应力的计算方法。实例计算结果表明:锻造偏心距从100 mm增至250 mm,机架的预紧系数分别从横向偏载工况下的1.12增至1.45、从纵向偏载工况下的1.14增至1.77,机架在纵向偏载工况下为了保证自身整体性所需的预应力更大。通过仿真分析进一步比较立柱与下梁间接合面的闭合状态,结果表明:相较于横向偏载工况,机架在纵向偏载工况下更易开缝且最大缝隙更大;对于纵向偏载工况,立柱的纵向挠度随着预紧系数的增加显著减小,且预紧系数增至1.8时,最大缝隙趋于0 mm,验证了计算方法的可行性。并基于偏载工况与预应力机架的研究,提出了在机架预应力的计算过程中有必要考虑纵向偏载产生的影响。

For the double-column push-up forging hydraulic press,the eccentric load condition in the forging process was analyzed,the transfer path of eccentric load was studied,and the objectivity that the vertical eccentric load always exists was clarified.Then,the mechanical model of double-column prestressed frame was established,and the stress state of frame under the eccentric load was analyzed.Combined with the research on the working process of the frame,the calculation method of prestress was determined.The example calculation results show that the forging eccentricity increases from 100 mm to 250 mm,the pretension coefficient of the frame increases from 1.12 to 1.45 under the horizontal eccentric load condition and from 1.14 to 1.77 under the vertical eccentric load condition,and the prestress of the frame is greater to ensure its integrity under the vertical eccentric load condition.Through the simulation analysis,the closed state of indirect joint surface between column and lower beam was further compared.The results show that compared with the horizontal eccentric load condition,the frame is easier to crack under the vertical eccentric load condition,and the maximum gap is larger.For the vertical eccentric load condition,the vertical deflection of column decreases significantly with the increasing of the pretension coefficient,and when the pretension coefficient increases to 1.8,the maximum gap tends to 0 mm,and the feasibility of the calculation method is verified.Based on the study of eccentric load condition and prestressed frame,it is suggested that it is necessary to consider the influence of vertical eccentric load in the calculation process for the frame prestress.