建筑工程项目管理的现状分析及控制措施

当前国民经济稳健发展,我国的建筑业发展也有显著提高。为了进一步拉动我国国民经济的发展,国家在基础设施方面加大了投资力度,改善工作环境,引进先进的建筑工程管理方案,在一定程度上提高了我国建筑产业的市场竞争力度,使得建筑企业抓住了难得的契机。     

Finite Element Optimization of Vee-ring Factor in Fine-blanking Process

The vee-ring is one of the most characteristic features of the fine-blanking process which is derived from the conventional blanking. With the vee-ring, a counter plate and some other working parameters, a component with a precise geometry and smoothly blanked surface can be produced without any major secondary operations. However, these working parameters are always empirically determined or determined by trial-and-error method, which is time-consuming and expensive. In this study, a numerical simulation method was used to analyze the effect of vee-ring factors on product quality, such as distance between vee-ring and punch, vee-ring height and blank holder force, so as to obtain as high clean cut ratio as possible. During the simulation, the model was assumed as axisymmetric one and the workpiece was considered as rigid plastic material, meanwhile the tools were defined as rigid bodies so as to shorten the computational time. A damage model taking into account the influence of hydrostatic stress was used to simulate material fracture in fine-blanking. The result obtained from the simulation indicated that with the help of vee-ring, the metal material near the shear band does not flow with the punch penetration and high compressive stress in the shear band is generated. Consequently, higher clean cut ratio can be obtained with a vee-ring model than the one obtained with a plane blank holder model. Furthermore, the longer the distance between vee-ring and punch is, the higher the height of roll-over becomes.