Deformation Cause of Seal Surface of Melt Gear Pump

　　The deformation of the sealing surface is characterized by uneven wear on the end face of the moving ring seal, large wear near the inner diameter, narrow wear marks and serious linear contact. The main reason for deformation of sealing surface is improper selection of ring material and too large linear expansion coefficient.

　　For the sealing rings and seals of high viscosity gear pumps, mosaic structure should be adopted, interference fit should be adopted. If interference fit is large, the sealing rings will be deformed and fractured under larger extrusion stress. If interference is small, the sealing will be easy to loosen at high temperature. The linear expansion coefficient of 316L stainless steel ring material is 2-3 times of that of impregnated PTFE resin, and the interference between ring and sealing ring is 0.25 mm. At working temperature, the fit part of sealing ring and ring can not expand and shrink synchronously, the interference amount changes, and the contact stress changes accordingly, which makes the seal deform.