用于粘性介质压力成形的介质性能的研究

粘性压力成形（VPF）采用一种半固态、可流动并具有高粘度的材料作为成形传力介质,粘性介质的性能对板材变形有很大影响,本文根据粘介质压力成形的要求,选择了3种不同分子量的粘介质材料,并讨论了它们的基本性能.采用剪切流变方法对3种粘性介质的流变性能进行了分析,获得了3种介质的转速-扭矩关系曲线,从而得出粘性介质应力应变随时间的变化规律.自行设计并制造了粘性介质的挤压实验装置,通过3种不同分子量的粘性介质的挤压实验,分析了挤压力随挤压速度及挤压比的变化规律.实验结果表明,随着挤压速度和挤压比的增大粘性介质挤压力增大,粘性介质有较强的速率敏感性.

Medium performance research used in the viscous pressure forming

Viscous Pressure Forming(VPF) uses a kind of semi-solid,flowable and viscous medium as pressure-carrying medium.Viscous medium has great effects on the deformation of sheet metal.According to the request of the viscous medium pressure forming,this paper chooses three kinds medium materials with different molecular weights and discusses their basic physical performance.Dynamic shear rheometer(DSR) is used to analyze the rheologic properties of viscous medium.Through tests,the relationship curves between rotational speed and torque of three different kinds medium and the changing law of stress and strain changed with time are obtained.Viscous medium extrusion equipment is designed and manufactured.Through carrying out the extrusion tests of three kinds of viscous mediums,the relationship curves between the extrusion speeds and extrusion force for different extrusion ratio are obtained.Experimental results show that the extrusion force of viscous medium increases with increasing extrusion speed and viscous medium is of very strong strain rate sensitivity.