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Technology for Obtaining Asymmetries of Stereometric Shapes of the Sealing Rings Sliding Surfaces for Selected Anti-Wear Coatings
ISSN: 0148-7191, e-ISSN: 2688-3627
To be published on September 15, 2020 by SAE International in United States
The article presents the methodology of obtaining asymmetric shapes of the sealing rings sliding surfaces. A very high product tolerance of 1 to 3 µm stereometric shape was taken into account for various types of wear-resistant materials that meet the requirements of adhe-sion of the anti-wear coating to the substrate. In particular, an analysis was made of the possi-bilities of using various product technologies, a modification of the grinder intended for profile grinding of the sliding surface of the rings was carried out, and the process of ring machining was determined. A very advanced stage of the production process is proper shaping, consistent with the-oretical assumptions based on the results of simulation tests. This shape should be maintained for all the rings in the experimental series both in cross-section and on the periphery of the ring. Maintaining the stereometric shape of the sealing rings sliding surface similar to the axisymmetrical model, with a product deviation of no more than a few micrometers, for any measuring section in the cross section on the periphery of the ring, gives the opportunity to veri-fy the impact of this shape on the parameters of oil film and friction loss. Failure to meet the condition of approximate axisymmetry leads to a variation in the thickness of the oil film be-tween the sliding surface and the cylinder bearing surface at the periphery of the ring due to the variation in shape. As a consequence, the distribution of the unit pressures on the periphery of the ring will also change. Such variables affect the change in the distance between the rings sliding surfaces and the cylinder bearing surface on different sections of the ring periphery, which determines the variation in the surface area of the oil film under the ring around the ring periphery. The interdependence of these parameters will affect the variable peripheral value of the internal resistance in the oil film during the movement of the piston rings. Experimental tests were performed determining the product quality of the asymmetry of ring shapes for selected anti-wear coatings. The article also presents the results of tests deter-mining the functional parameters of the produced rings, i.e. measuring the clearance in the joint, the tangential force of the piston rings, controlling the quality of the rings by means of the light gap method, measuring the shape by using a profilograph. Tests of the microstructures of the metallographic specimens of the top layers of coatings were carried out, as well as the tests of transition layers and the ring base material prior to and after the running-in period with the use of a SEM scanning electron microscope and an LM optical microscope. Key words: sealing rings sliding surface, friction loss, oil film.