Session: 05-01-02: Condition Monitoring, Metrology & Instrumentation

Paper Number: 170075

Investigation of Ultrasound Emissions of Deep Groove Ball Bearings for Condition Monitoring in Screw Pumps 

Screw pump technology is highly adaptable to a wide variety of application scenarios. This flexibility increases the need for a comprehensive understanding and continuous monitoring of pump conditions. Condition monitoring enables the prediction of performance as well as wear propagation, and supports the analysis of operational improvements, such as increased efficiency and noise reduction. Ultrasonic detection could be particularly well-suited for monitoring screw pumps, as a wide range of its physical processes are prone to emit acoustic signals in the ultrasonic frequency range. The inherently limited propagation of ultrasonic signals enables spatially resolved monitoring, making it possible to isolate and assess the condition of individual components within complex technical systems.

Investigating the potential of passive ultrasonic signal acquisition for component-specific condition monitoring requires excluding system-wide interferences within the screw spindle structure. Unlike conventional vibration analysis or active ultrasonic testing, the presented approach relies on passive signal acquisition to characterize bearing conditions without the need for external excitation. This enables a non-invasive, energy-efficient monitoring strategy that can be integrated into existing component structures. For this purpose, a dedicated experimental setup was developed, in which deep groove ball bearings of three different sizes and types were examined as isolated pump components. For each size, a test matrix of 20 operating points was defined, combining four rotational speeds with five levels of axial load (0%, 10%, 25%, 50%, and 100% of the bearing’s maximum static load rating). The passive ultrasound measurements were conducted with sensors featuring different frequency bandwidths to assess the influence of transducer characteristics on the measured frequency response. allowing for an unbiased experimental confirmation of the most relevant frequency bands that are effective for condition monitoring. An application-oriented measuring chain with a 10 MHz sampling rate ensured high signal fidelity across sensor configurations.

The evaluation focused on frequency spectra in order to study the correlation between acoustic emissions and specific operating points of the bearing system. In addition, various methods for practical feature extraction were explored during signal processing to assess the assignability of ultrasonic signals to characteristic bearing conditions. This lays the foundation for integrating machine learning in future work, thereby supporting the industrial applicability of passive ultrasonic sensing.

The aim of this paper is to explore the applicability of passive ultrasonic monitoring at the component level, with a particular emphasis on the behavior of acoustic signals and their information value in relation to the sensor setup and the system's operating state.

Presenting Author: Michael-Jiri Fikacek Leistritz Pumpen GmbH

Presenting Author Biography: Michael Fikacek is a development engineer at the company Leistritz Pumpen GmbH in Nuernberg, Germany. His research focuses on the application of ultrasonic sensing for condition monitoring. He is currently working on a project exploring the applicability for the state identification of screw pumps.

Authors:

Michael-Jiri Fikacek Leistritz Pumpen GmbH
Oliver Troßmann Leistritz Pumpen GmbH
Christoph Bayer TH Nürnberg