Method of Preventing Abrasion at Sliding Portion of Metal-Product

Author:  Yoshio Miyasaka
Source:  US Patent 5,592,840
Doc ID:  2023010
Year of Publication:  1997
Abstract:  
By shot-peening, shots having almost spherical shape are impacted against a surface of a portion of a metal-product, the portion being one which is to be subjected to sliding action. The shots have a hardness higher than that of the metal-product. By the shot-peening, the surface of the metal-product is heated to a temperature higher than a predetermined temperature and very small concave portions, each having a circular arc-shaped cross section, are formed due to the impact of the shots. As a result, the structure of the surface layer of the sliding portion has high internal stress, high hardness and high toughness. Further, since very small concave portions are formed on the surface of the sliding portion, the surface tension of lubricating oil is not decreased and a stable oil film can be formed. In addition, the surface retains high hardness and toughness, even if sliding is performed for long time periods, and the concave portions are not deformed so that a stable oil film can be maintained.