基于主要因素图的MG300/730-QWD机组事故分析

根据唐山矿业公司使用的MG300/730-QWD机组事故状况统计,利用主要因素图分析法予以分析,找出影响事故的主要因素,即行走箱、变频器、截割电机事故,针对主要因素采取相应对策予以解决,达到减少机电事故,确保设备正常使用的目的。

Microstructural evolution and creep properties of Mg-4Sn alloys by addition of calcium up to 4 wt.%

The effects of addition of calcium up to 4 wt.% on the microstructure and creep properties of Mg-4 Sn alloys were investigated by the impression creep test. Impression creep tests were performed in temperature range between 445 and 475 K under normalized stresses σ/G(where σ is the stress;G is the shear modulus) between 0.0225 and 0.035. Optical microscopy and scanning electron microscopy were used to study the microstructure of samples. It is observed that the addition of Ca more than 2 wt.% suppresses less stable Mg Sn2 phase, and instead forms more thermally stable phases of Ca-Mg-Sn and Mg2 Ca at the grain boundaries which improve the creep resistance of Mg-4 Sn alloys. According to the stress exponents(6.04<n<6.89) and activation energies(101.37 k J/mol<Q<113.8 k J/mol) which were obtained from the impression creep tests, it is concluded that the pipe diffusion climb controlled dislocation creep is the dominant creep mechanism.

关于电铲用交/直流传动优劣的争论

概述了电铲交/直流传动的发展过程,对旧式的MG机组的直流传动,静态直流传动,比赛勒斯(Bucyrus)公司的Acutrol交流传动,P&H公司的交流传动,GE公司的DC2000等传动装置做了介绍和对比。