Investigation into the Reciprocating Sealing Performance Based on an Optical Test Method

Abstract

Reciprocating seals are essential elements for hydraulic cylinders. The status of the contact area between the seal and the counterpart directly determines the sealing performance. An optical test rig for the O-ring seal was constructed in this study to investigate the tribological characteristics among the contacting zone, where the cylinder was changed to be transparent and a microscope is employed to observe and record the sealing status. A numerical method coupling finite element analysis (FEA) and the mixed lubrication procedure is implemented for the theoretical analysis. A comparison between the simulation and the experiment for the sealing width, friction force, and leakage was conducted. During the reciprocating motion, it was found that the oil film thickness adhering onto the cylinder’s inner wall was not even along the axial direction and that the leakage oil would be accumulated at the stroke-end position because of the seal’s scraping effect. The topographic indicators for the contact mechanisms are discussed, and the results demonstrated that the implementation of the mean peak width (Rsm) for the asperity radius could obtain more reasonable results. The performance of the O-ring seal at different velocities was theoretically and experimentally investigated. With an increase in velocity, the leakage rate increased and the friction force decreased. The simulation results are consistent with the experimental results both in the overall trend and in the order of magnitude.

Keywords:

• Optical test rig
• O-ring seal
• contact area
• topographic indicators
• friction and leakage

Additional information

Funding

This work was supported by the National Natural Science Foundation of China (Grant No. 518902883), Open Foundation of the State Key Laboratory of Fluid Power and Mechatronic Systems, and China Scholarship Council.