NSK Technical Review introduces cutting-edge R&D activities and new products. (Past NSK Technical Journal also remain available bellow.)

No.2607　Gear Fault Diagnosis AI for Efficient Operation of Rotating Machines: A Physics-informed Approach

Inside rotating machines such as wind turbines, not only rolling bearings but also gears continue to rotate without rest. If gear damage occurs and the rotating machine keeps operating without anyone noticing it, the damage can lead to sudden shutdowns and severe consequences. However, when operating conditions such as the rotational shaft speed change, the vibrational characteristics of gears also change. Under such conditions, conventional vibration-based and AI-based diagnostics have sometimes struggled to make reliable decisions. NSK therefore studied an AI model that also learns the physical phenomena underlying vibration signals and examined whether it can stably diagnose gear damage even under previously unseen operating conditions.

No.2606　Foundational development, modeling and configuration of state stabilizing mechanism to maintain axial tension in ball screw feed drive systems

This study presents a state stabilizing mechanism (SSM) that can maintain consistent axial tension in ball screw feed drive systems, even when the screw shaft is elongated due to thermal expansion. Hydraulic fluid sealed within a pressurized chamber expands from the intrinsic heat generated by bearing rotation, allowing the unit to autonomously maintain stable axial tension. Model calculations and experimental results have demonstrated the functionality of the mechanism and validate it as a solution that may be considered during design and specification review. The SSM is planned for incorporation in future products as the “NSK Feed Drive Adjuster.” The article below was originally published in an academic journal of the Japan Society of Mechanical Engineers. It has been reproduced here with permission.

No.2603　Lubrication Life Formula(Lubrication Pentagon Theory)

To achieve both further reduction in torque and extended life of bearings, we are working on deriving a lubrication life formula. This effort involves using five predictive formulas based on the Lubrication Pentagon Theory to forecast lubrication life, with the expectation of theoretically optimizing bearing performance. Additionally, we are making efforts to enhance the accuracy of the lubrication life formula by utilizing NSK's original visualization techniques.

No.2601　Establishing a Spalling Life Prediction Method for Rolling Bearings utilizing “NSK Micro-UT™” A highly accurate method for predicting Weibull plots of the spalling life of rolling bearings has been established using NSK's original steel cleanliness evaluation method, NSK Micro-UT™, and a life calculation formula derived from a new theory. This method supports the design and selection of more appropriate rolling bearings and can contribute to the realization of safety, security, and carbon neutrality.