The sand retention apparatus is composed of an upper joint (1), a central tube (2), a retention ring (3), a sealing element (4), a spacingring (5), an adjusting ring (6) and a bell mouth (7).
Between the chain and ringspacing are like a well-calculated and carefully processed.
连环与环之间的间距都像是有着周密计算和精心加工的。
3
The experiment result shows that the spacing of onion rings, which is the most prominent features of most friction stir welds, decreases with the distance of onion ring to centerline increasing .