基于特征和知识的精密注塑模设计和制造系统

采用先进的CAD/CAM技术对传统模具设计制造方法进行改造,是提高模具设计制造质量和效率的关键.此文提出基于特征和知识的才法构造精密注塑模设计和制造系统,并介绍了系统的总体方案和系统包含的各模块功能.这一系统是浙江省科委八五攻关项目“精密注塑模设计和制造(CAD/CAM)技术”的核心.     

Dissolution characteristics of 226Ra from phosphogypsum

The paper presents the results of the dissolution characteristics of 226Ra from phosphogypsum, a by-product from phosphate fertilizer industries. Leachability of 226Ra in distilled water and rainwater have been examined under different leaching conditions such as contact time, solid:liquid ratio and simulating natural conditions. The concentration of 226Ra activity in the leachates ranged from 0.07 to 0.53 Bq l(-1). Study indicated that leaching of radium may be slow in field conditions near the phosphogypsum stock piles.