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Yang S.,Xiangtan University | Wen Z.,Xiangtan University | Li L.,Hunan Valin Xiangtan Iron and Steel Co. | Tan Y.,Xiangtan University | Chen X.,Xiangtan University
Zhongguo Jixie Gongcheng/China Mechanical Engineering | Year: 2014

Based on the meshing theory, the meshing equations of a globoidal cam mechanism with error were deduced. By using the differential method, the motion accuracy influence coefficient expressions of the globoid cam mechanism were obtained. Firstly a simple tolerance allocation method was proposed. Then the improved optimal limit deviation tolerance allocation method was proposed by comprehensively considering the processing cost, size and the assembly performance of practical engineering. On the basis of that, the globoidal cam mechanism tolerance allocation problems were discussed. Targeted to a specific globoidal cam mechanism transmission system example, the tolerance distribution problems were solved by using two methods. The results show that the improved optimal limit deviation method is reasonable. A tolerance allocation method is provided for the globoidal cam mechanism, and provides reference for other spatial conjugate transmission mechanism tolerance allocation.

Ma C.,University of Science and Technology Beijing | Zhang J.-L.,University of Science and Technology Beijing | Qi C.-L.,University of Science and Technology Beijing | Yin J.,Hunan Valin Xiangtan Iron and Steel Co. | And 2 more authors.
Guocheng Gongcheng Xuebao/The Chinese Journal of Process Engineering | Year: 2012

Based on the physical and process properties of 9 kinds of pulverized coal in Xiangsteel, including ash fusion point, grindability index, ignition point, explosibility, fluidity, combustibility and reactivity, all the properties of bituminite and anthracite coals are evaluated, and reasonable options recommended. It is concluded that (1) Hengda is the best kind of bituminite to be used in Xiangsteel blast furnaces, Weihua bituminite the next choice. Their combustion rates are both above 85%. Because of low sulphur content, combustion rate over 70%, high grindability, good fluidity and high ash fusion temperature, Yangyang, Xiangyindu and Xingxing anthracite are suitable to blast furnace injection. (2) In accordance with the principle of coal blending, two options are recommended: mixture of Hengda, Xiangyindu and Baisha, and mixture of Weihua, Xingxing and Yangyang.

Zhang H.,Hunan Valin Xiangtan Iron and Steel Co. | Xiao H.,Hunan International Engineering Consulting Center Co. | Bao Y.,Control Iron and Steel Research Institute, China
Jinshu Rechuli/Heat Treatment of Metals | Year: 2015

Through thermal expansion experiment on Formastor-FII thermal dilatometer, combined with observation of microstructure and hardness measurement, effect of Mo content on undeformed austenite continuous cooling transformation of 1000 MPa grade low carbon bainitic steel was investigated, and CCT curves of the steels with different Mo contents were measured. The results show that the higher Mo content reduces the temperature of phase transformation point of bainite, narrows the bainite transformation temperature range, and makes the CCT curves move to right. © 2015, Chinese Mechanical Engineering Society of Heat Treatment. All right reserved.

Qi C.-L.,University of Science and Technology Beijing | Zhang J.-L.,University of Science and Technology Beijing | Lin C.-C.,University of Science and Technology Beijing | Yin J.,Hunan Valin Xiangtan Iron and Steel Co. | And 2 more authors.
Beijing Keji Daxue Xuebao/Journal of University of Science and Technology Beijing | Year: 2011

Seven samples of a blast furnace at representative positions were analyzed by scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), X-ray diffraction (XRD) and atomic absorption spectrometry to study the erosion of carbon bricks at the BF hearth sidewall by harmful elements and the mechanism of pulverizing fracture. The results show that the erosion mechanism of carbon bricks at different parts of the hearth is different. In the first layer the erosion is mainly caused by the catalytic effects of harmful elements in the carbon loss reaction and the generation of leucite; in the upper area, penetration of K into brick work joints leading to a quality change of carbon bricks plays the leading role; in the tuyere, Zn is the main cause of erosion; but in the taphole the content of K is larger, with enrichment of Pb. It is also found that a harmful element has different effects at different parts of the hearth. In the upper area, the erosion mechanism is mainly the catalytic effect of K in the erosion reaction, but in lower part is the penetration of K into carbon bricks leading to a quality change of carbon bricks; Zn significantly crystallizes on carbon bricks in the tuyere, however in the hearth bottom Zn attaches to carbon bricks without obvious crystallization.

Wang S.-C.,Central South University | Li Z.-C.,Central South University | Yi D.-Q.,Central South University | Cao Z.-Q.,Hunan Valin Xiangtan Iron and Steel Co. | Zhang H.,Central South University
Zhongnan Daxue Xuebao (Ziran Kexue Ban)/Journal of Central South University (Science and Technology) | Year: 2011

Microhardness tester, optical microscope and electron back scattered diffraction technique were used to examine the property and microstructure of a low temperature tempered 20MnCr5 carburized gear. {110}α polar figure of Martensite was calculated according to the K-S and N-W orientation relationship. Orientation distribution of Martensite at the center of the gear was examined by electron back scattered diffraction technique. {110}α polar figure of Martensite in a selected prior austenite grain was plotted. The orientation distributes randomly in the whole scanned area, but distributes regularly in local area. The misorientation of the scanned area distributes mainly below 5° and above 45°. In order to characterize the orientation distribution law in local areas, stereographic projection of Martensite {110}α in a selected prior austenite area was plotted. The orientation relationship in the selected prior austenite is determined to be mainly N-W orientation by fitting the polar figure. Discrepancy between practical and theoretical orientation distribution is interpreted by cooperative strain mechanism.

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