为了研究不同压下量和送进量对拔长过程中锻件表面质量的影响，建立拔长折叠产生的判断条件，以5CrNiMo 模块锻件为对象，用有限元软件 DEFORM-3D 建立了相对应的拔长模型，分析压下量和送进量比(M 值)对最大折叠角和折叠深度的影响．结果表明，产生拔长折叠的 M 值临界区间为0．8 ～1．0．由此建立了拔长过程中锻件表面折叠产生的判据:M 值低于0．8 ～1．0 这一区间时，锻件表面不产生折叠;M 值属于或超出该区间时，锻件表面产生折叠．

In order to reveal the effects of reduction and feed amount on the surface quality of forgings during the stretching,and to establish a criterion judging the occurrence of stretching folding,a stretching model of 5CrNiMo die block forgings is constructed by means of the FEM software DEFORM- 3D,and the effects of the reduction- to- feed amount ratio (namely the M value) on the maximum folding corner and the folding depth are discussed.It is found that the stretching folding occurs at a critical M interval of 0.8 ～1.0.On this basis,a criterion to judge the occurrence of folding during the stretching is established,that is,the folding of forging surfaces can be avoided when M is less than the range of 0.8 ～1.0,while the folding occurs when M is within or exceeds the range of 0.8 ～1.0.