大型模锻压机极低速驱动系统的仿真建模、实验验证与性能分析

Simulation modeling,experimental verification and performance analysis of die forging driving system on extremely low speed

高性能复杂整体模锻件的等温制造要求大惯量模锻装备必须在极低速下稳定运行,但非线性、时变的锻件变形抗力和柱塞缸所受的非线性摩擦力导致该装备难以在极低速下获得所需的锻压性能。针对这一问题,在考虑锻件的流变特性、低速下特有的静-动交替变换的摩擦特性以及工艺过程和装备运行之间关联作用的基础上,建立基于AMESim与Simulink的大惯量模锻装备低速锻造过程的联合仿真平台,通过实验验证该仿真平台的有效性与精确性,实现低速锻造过程的仿真建模。利用该平台对系统性能的影响规律进行研究,首先揭示了材料成形过程对系统低速性能的影响规律:比较流变特性参数对系统驱动能力的影响程度。研究结果表明:材料参数对系统的驱动力影响由大至小依次是物理化学性质常数y、强度系数c、材料硬化指数n与应变速率敏感性指数m;其次,研究了摩擦力对低速爬行的影响规律。导致低速爬行的2个条件是实际速度接近摩擦的临界速度以及最大静摩擦力与库仑摩擦力的差值太大。这些规律可为大惯量装备的极低速稳定运行提供基础与保证。

The steady operation of die forging equipment with large inertia was proposed in consideration of the isothermal forging of the sophisticated and integral forgings with high performance. The required forging properties of equipment at extremely low speed were acquired difficultly because of the nonlinear and variable resistance of deformation and the nonlinear friction force. In view of this question, the rheological properties of forging, the static-dynamic alternated friction at low speed and the relevance between technology and equipment were analyzed firstly, and then the united simulation platform of forging process on low speed of die forging equipment with large inertia based upon AMESim and Simulink software was established. And the availability and accuracy of simulation model were proven by experiment. On this simulation platform, the effect rules of system performance were researched. The effect rule of material processing on low-speed performance was revealed, and the influences of rheological parameter on driving force were compared. Then the speed creep caused by friction force in plunger cylinder was analyzed through simulation. The results show that the driving force was affected heavily by material constant y, followed by the strength coefficient c, the harden ability value n and the strain rate sensitivity index m. Two conditions about low velocity creep are that the difference between maximum static friction force and the coulomb friction is too big, and the actual speed is close to the critical velocity. The basis and guarantee of steady operation at extremely low speed are provided by these rules.