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On the piston ring design

Addtime:2013-7-12 17:14:01 Hit:

 Since gasoline and diesel piston structure height reduction, compression ring axial height correspondingly reduced, especially in the face 20MPa cylinder explosion pressure, the mechanical structure of the increasingly high demand, all this requires enhanced strength and resistance to the side of the piston ring grindability. Steel materials are particularly suited to these requirements. Compared with cast iron, steel has good mechanical dynamic load carrying capacity, and therefore the case where the bending load increases with a high fatigue strength. Of course, by surface coating and surface treatment effect can be partially reduced iron and steel, the difference between the dynamic strength. Tests showed that by additional chemical treatment (CPS Act) enables the dynamic strength of nitrided steel rings by about 30%.

First application of chromium is 13% or 18% of the high chromium martensitic steel, a material by generating fine distribution of chromium carbide and generated additional nitrided layer significantly improved the hardness of the surface layer, thereby obtaining good wear sex. If you want to use the quenched and tempered low alloy Cr-Si, then ring the work surface coating is required.
In the last 15 years, the world's first gasoline engine compression ring by a ring instead of cast iron steel ring, which especially in Europe and Japan prefer to nitriding steel ring. In high-speed gasoline engine use conditions, are of low axial height of a steel ring has become a standard part in the development of the engine during this first ring than 90% of a steel ring are nitrogen, and the first two rings in most cases, lower-cost iron ring, and according to their respective functions required to select the appropriate structure type and work surface coatings.

Today piston ring application of various quality cast iron and steel. First examine the cast iron materials, in accordance with the material strength, elongation, fatigue strength and wear resistance and other indicators characterize the carrying capacity, the choice of the full range of casting quality are shown in Table 1. The first compression ring should be particularly preferred having a high bending strength and elastic modulus of iron, the matrix of martensite, to obtain high hardness, good wear resistance can have side.

Second piston ring coating can be applied without the development of a state in the transfer of heat treatment showed lamellar structure refinement casting quality materials, by generating chromium, vanadium, manganese and tungsten carbide special elements, as well as Markov body matrix, to obtain a good abrasion resistance. And GOE44 malleable iron is a refinement of pearlite in the matrix organization in a targeted manner to generate residual carbide component materials, can high resistance to tangential force strength and good wear resistance combined.

Because of the material strength and fatigue strength and good wear resistance have become increasingly demanding, and now tend to further optimize the generation of spherical graphite so static (assembled state) and dynamic loads to obtain a particularly high flexural strength, while using bainitic matrix organization to obtain the piston ring side and lower wear rate of the working surface.