Increasing of Working Pressure and Life Span for Homogenizers

Abstract

Currently, when a high-pressure homogenizer is operated at internal pressure of 200 MPa, fatigue failure occurs in the cylinder after about 1 million operations, which is much shorter than the expected lifetime. The fatigue cracks caused by fatigue failure are parallel to the axial direction and propagate from the inner surface of the cylinder. This suggests that the fatigue failure was caused by periodic circumferential stresses applied to the microscopic scratches on the inner surface of the cylinder during operation. Therefore, we adopted Shrink-Fit Process and Autofrettage Process. It was found that the circumferential stress generated on the inner surface of the cylinder could be reduced by 267 MPa by applying the Shrink-Fit. It was found that the circumferential stress on the inner surface of the cylinder could be reduced by 510 MPa by applying the Autofrettage-Process. The obtained values were used to predict the life time of the specimens based on S-N diagrams. It was found that the target life of 10 million cycles could be achieved by Shrink-Fit and Autofrettage.