Failure Analysis of End Face Seal of Floating Side Plate of Melt Pump

When the melt pump works, the high-pressure oil in the pressure chamber is led from the oil hole to the outer end of the side plate, and acts in the closed oil chamber formed by the ear seal ring and the compensation force groove, which generates the compensation force. The oil in the gear working chamber acts on the inner end face of the side plate to form the reverse thrust force, which forces the side plate to the end face of the gear to ensure various working pressures. Under the force, the side plate can be automatically pressed on the end face of the gear.

Melt pump adopts automatic compensation structure of axial clearance. The main failure forms of end seal are serious wear of floating side plate, increased clearance between side plate and gear end face, and reduced volume efficiency of melt pump. The sealing performance of the end face of the side plate depends on the following two points: 1. Compression ratio of the floating side plate; 2. Tilting moment of the floating side plate.

Through the analysis of wear of floating side plate of melt pump, it is concluded that the overturning moment of side plate is the key factor that causes the local compression ratio of side plate to exceed the allowable value of material, and then causes serious local wear of side plate. In order to improve the sealing performance of floating side plate, the side plate structure should be designed asymmetrically to reduce the overturning moment.