Development of Evaluation Method for Inner Defect of Steel Balls

作者：Nagashio Masaki^*; Hanabusa Takao

来源：Journal of Japanese Society of Tribologists, 2010, 55(5): 341-347.

• rolling bearing
• steel ball
• SUJ2
• non-metallic inclusion
• rolling fatigue life
• flaking
• ultrasonic flaw detection

The cleanliness of bearing steels strongly affects rolling fatigue life of bearings. In recent years, cleanliness of the material of steel balls used as rolling elements of bearings improve remarkably, and rolling fatigue life of steel balls get longer. However, problems concerning to non-metallic inclusions in steel have not been solved. In addition, the introduction of cheap materials is considered for cost reduction, but the cleanliness of these materials is generally bad. Therefore we developed an inspection system with ultrasonic flaw detection as a detection method for non-metallic inclusions in steel balls. This system can detect the non-metallic inclusions, which have more than a diameter of approximately 30 mu m and exist within a depth of 300 mu m from the surface of the steel balls. In addition, the rolling fatigue life test revealed that the Weibull distribution for defective balls is distinctly different from the Weibull distribution for non-defective balls. The effectiveness of the present inspection system was confirmed by the fatigue life test which showed that defective balls have shorter lives than non-defective balls.

• 出版日期2010