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Refractory metal powder metallurgy products, automatic loading equipment development and the automatic loading process

Author: ChenHaiFeng
Tutor: LuoXueKe；ChenFeiXiong
School: North China University of
Course: Mechanical Engineering
Keywords: refractory-metal Cold isostatic pressing(CIP) vibration platform compaction density
CLC: TP29-A3
Type: Master's thesis
Year: 2009
Downloads: 83
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Abstract

Cold isostatic pressing(CIP) is one of powder metallurgy techniques, which is based on that liquid is unable to be compressed and able to transfer press equally. The advantages of green compacts formed by CIP are high strength, high density, homogeneous density and so on. Especially, the CIP could achieve near net-shape or net-shape forming. Therefore, it is a considerably important way among modern molding techniques to manufacture structural parts, and is widely applied in the refractory-metal production industry. However, there is some deficiency in its assistant technics. For large-size tungsten and its composites, there have not yet been special equipment to assist loading by far, while handwork loading and pise are used. Pise strength and frequency can not be controlled in handwork pise process, which leads to low usage rate of raw materials, low finished product rate, and high requirement for workers’ loading experience. In addition, it is difficult to implement normalization and batch production. Furthermore, it is labor intensive and low efficient . These problems are in dire need of being solved.A number of vibration experiments have been done on different equipment to solve the above problems, and vibration response laws of tungsten powder are obtained on different vibration equipments.Compression experiments on impact platform show that when swing reaches 3.5 mm and above, compaction density of tungsten powder will reach the measurement by the means stipulated by the Chinese national Standard, which meets the need for compaction density in powder metallurgy technics of tungsten. By high-frequency and long-time vibration experiments, the delamination of different-size particles is not found in compressed powders. So impact platform can absolutely replace handwork to be applied to tungsten loading and compression before Cold isostatic pressing. But experiments also show that great noise of impact platform impairs workers’ hearings to some extent, and it is difficult to implement great loads.Compression experiments on motor vibration platform show that compaction density of powder increases with vibration intensity, and the compaction density of tungsten powder will reach the measurement by the means stipulated by the Chinese national Standard as long as the vibration intensity reaches 2.91 g. Because vibration intensity increases linearly with swing and the square of vibration frequency, compression of metal powders of different weights can be achieved by increasing swing and vibration frequency. There are weak impact to the groundsill and low vibration noise on the kind of equipments in comparison with impact platform, and it is easy to implement great loads.The motor vibration platform ZDPT1500 has been designed and manufactured through comparing and analyzing experiment results, equipment costs and environment factors. ZDPT1500 is fit for automatic loading of refractory-metals before CEP. It has passed loading tests of different materials, and it has surely achieved expected goal. The usage rate of powders has risen above 10 %, and production efficiency above 60 %. At the same time, workers’ labor intensity has been greatly reduced. In a word, this paper has basically realized production technics of automatic loading of refractory-metal powders before CEP.

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