The Influence of Micro Morphology on Leakage of Metal Seals in Hydraulic Component

Metal contact sealing is commonly used in hydraulic components under complex conditions such as high temperature and high pressure. When the sealing force is constant, the micro-contact condition of the sealing pair determines the sealing effect. This article uses finite element simulation to study the relationship between leakage and rough surface morphology from a micro perspective. Firstly, rough surfaces were constructed based on the point cloud function which can be described by the different root mean square of roughness-(RMS-roughness) and autocorrelation functions. Then, sealing contact models were developed using these rough surfaces separately combine with a smooth surface to simulate different micro-contact situations under the same contact pressure. Subsequently, the leakage channel was extracted for leakage calculation, and the RMS-roughness, autocorrelation length, and average height of sealing gap were obtained to conclude the relationship between the actual contact area and leakage amount. The research results indicate that under certain contact pressure conditions, the leakage rate increases sharply approximately exponentially with the increase of the RMS-roughness. However, the leakage amount increases not significantly with the increase of autocorrelation length. The findings provide effective guidance for the design of metal sealing structures.

I. Introduction

Leakage failures are widely seen in the industry, so many studies related to seal leakage problems have been conducted in an attempt to solve them by revealing their mechanisms [1]–[2]. At present, the research on the sealing performance of sealing structures mainly focuses on the macroscopic mechanics and process parameters triggered by the contact width and pressure of the macroscopic sealing interface to study the performance of the sealing structure [3]–[4]. In metal contact sealings, two metal interfaces contact with each other under the action of sealing forces to form a sealing band and play a sealing role. However, the existing processing technology cannot make the engineering surface reach a completely smooth standard, and the enlarged engineering surface can be found to be covered with micro-convex bodies of different sizes [5]. Moreover, the contact between the two surfaces is actually the contact of micro-convex body on its surface, and the actual contact area of the surface is much smaller than the macroscopic contact area. In the macroscopic contact surface of the sealing surface, the voids around the uncontacted micro-convex bodies penetrate each other and form a leakage channel, making the fluid leak from the high-pressure side to the low-pressure side under the action of pressure.