Development of Testing Facilities for Verification of Machine Condition Monitoring Methods for Low Speed Machinery

Abstract

Machine condition monitoring (MCM) of low speed machinery is highly challenging task. Methods of MCM of machinery operating at a speed of 500 to 3000 rpm are well-developed including wear debris and vibration monitoring (both instrumentation and signal processing). Machinery operating at a speed below 500 rpm is usually grease lubricated and wear debris analysis cannot be effectively used. Monitoring of vibrations at such speed is very difficult because conventional accelerometers give very week signal especially at a speed below 100 rpm. There is a vital need to develop new approaches to monitoring fault development on low speed machinery, which include new sensors and alternative methods such as sound emission and ultrasonic emission. Essential part of this process is development of testing facilities that enable modeling of different combinations of loading conditions that take place on low speed machinery and verify new MCM methods. For this purpose a design study has been conducted to develop methods of modeling of different combinations of loads on bearings and gears operating at low speed. This study resulted in the development of a unique highly versatile test rig presented in this paper. It enables modeling of different types of bearings operating at a speed of 30 to 600 rpm under a combination of different loading conditions, in particular, steady load, impact load, swinging load, axial load and rumble. It also enables modeling of transitional processes in shaft-mounted, flange-mounted and foot-mounted gear drives under different loading conditions (start up, coast down, increase or decrease of speed). Special instrumentation enables monitoring of the supply frequency, phase current, power consumed and taking these parameters for recording.