榨螺失效分析
Wear Failure Analysis of Squeezing Sleeves
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摘要: 螺旋式榨油机在我国得到普遍应用。榨螺轴是关键部件。榨螺磨损失效分析有助于选材及提高榨螺寿命,但还缺乏系统深入研究。
本文分析了榨油机中油料在榨膛的运动特征及榨螺的受力情况,认为榨膛可以分为三个区,即“进料区”、“预榨区”及“压榨区”。在压榨区,榨膛压力高而且油料变成高紧实度的“不可压缩体”,因此榨螺受到高应力碾研磨损,而且磨损最严重。对榨螺的宏观形貌的观察可资证明。
从压榨区的榨螺上取样进行磨面及磨损表层截面的SEM观察表明;榨螺受到形变磨损、切削磨损、撕裂磨损、疲劳断裂磨损及油液的微区高压冲蚀磨损。切削磨损是造成榨螺失效的主要原因。合金白口铸铁具有整体高硬度及含有大量高硬度碳化物,因此制成榨螺抗磨性比渗碳钢更高。Abstract: Spiral seed squeezing machines are commonly used in our country to produce vegetable oil.The spiral squeezing sleeves slipped onto the axis are the main parts doing the work of squeezing the seeds.The wear life of them shall be very important to the effective service of the machine The wear failure analysis of these sleeves was done in this paper.The squeezing chamber in the machine can be divided into 3 zones, namely, "feeding zone", "presqueezing zone" and "squeezing zone".Because the squeezing pressure in the last zone is high and the seeds become highly compacted "non-compressible bodies" the sleeves in that zone are sustaining high stress grinding wear and wears fast This is proved by the wear morphology of these sleeves.Wear failure analysis is mainly done on them.The SEM examinations of the wear face and section through the subsurface show that the wear mechanisms of the sleeves are; deformation wear mechanism,cutting wear mechanism, tearing wear mechanism and fatigue wear mechanism by non-compressible bodies and high pressure erosive wear mechanism by liquid oil produced. The main causes of failure are the former two mechanisms.Alloy white cast iron con taining carbide of high hardness and having high macro-hardness was suggested to make those sleeves to replace carburized steel and proved to be much more cost effective.