摘要
在大型锻件锻造工艺理论与技术领域 ,首先 ,对普通平板间镦粗圆柱体 ,根据其高径比 H /D不同 ,提出了两个新理论 :H / D>1,刚塑性力学模型的拉应力理论 ;H / D<1,静水应力力学模型的剪应力理论。前者打破了镦粗体 (不管高径比大小 )内三向压应力传统之说 ,并为轴对称塑性体的广义滑移线解和主应力分块法、数值模拟求其应力场提供了力学模型 ;后者解决了大型饼类锻件中出现的“夹馅饼”缺陷的难题。在此基础上又提出了锥形板镦粗的新工艺及其力学原理。在拔长工艺理论方面 ,应用方柱体镦粗的两个新力学模型与拔长的刚端影响问题 ,论证了只有砧宽比一个工艺参数的不足 ,而应补充一个新的工艺参数——料宽比 ,才能正确描述拔长体中心区域的应力状态与有效控制锻件质量。并进一步解决了该拔长理论工艺参数量值的合理匹配与确定。在“锻造条件对毛坯内部空洞闭合的影响”研究中 ,提出了增加料宽比对横向拉应力控制的“新 FM法”。在此基础上提出了横向无拉应力锻造法。上述工艺理论指导工艺生产 ,可大幅度提高锻件的质量。
In the field of the forging technology theories and techniques of heavy forgings,first,two new theories are advanced for a cylinder upset between common flat platens,based on the different ratios of height to diameter H/D.The new theories include a tension stress theory of the rigid-plastic mechanical model when H/D>1 and a shearing stress theory of the hydrostatic stress mechanical model when H/D<1。The former breaks through the traditional opinion of three-dimensional compression stresses existing in an upsetting body (no matter how much the ratio of height to diameter is)and offers a mechanical model for the generalized slip-line solution of the axi-symmetric plastic deformation body,for the mechanical slab method and the numeric simulation which are used to calculate the stress field.The latter solves the difficult problem of the 'meat pie' defects existing in the heavy disk forgings.On the basis of the above theories,a new technology of the cone-shaped platen upsetting and its mechanical principle are proposed. In the aspect of the stretching technology theory,it is demonstrated that only when a new technology parameter--the blank width ratio,except for the technology parameter--the anvil(tool)width ratio which is not complete,is complemented,can the stress state at the central zone of a stretching body be correctly described and the quality of forgings be effectively controlled,with the aids of the two new mechanical models of upsetting a square body and the effects of the rigid ends of stretching. The problem of the reasonable matching and determination of the technology parameters of the stretching theory is further solved.In the research of the influence of the forging condition on closing the internal pores in blanks,the New FM Method is advanced,which demands increasing the blank width ratio so as to control the transverse tension stress.The forging method without the transverse tension stress is proposed based on the methods described above.The quality of forgings can be greatly raised,if the technology theories are used to conduct the technology production.
出处
《大型铸锻件》
1998年第2期8-13,共6页
Heavy Casting and Forging
基金
国家自然科学基金资助重点项目课题 (No.5 92 35 10 1)
机械工业部教育司科技基金项目 (No.92 2 5 10 12 )
关键词
锻造工艺
刚塑性
静水应力
大型
锻件
锻造
Forging Technology,Rigid-Plasticity,Hydrostatic Stress,Cone-Platen Upsetting,Anvil Width Ratio,Blank Width Ratio,Cone-Anvil Stretching.
