Experimental study on the influence of flexible bearing clearance on natural frequency of harmonic reducer

Abstract

Harmonic reducer is a transmission device with high transmission ratio and high accuracy, which is widely used in robotics and other instruments. Backlash reflects the positioning accuracy of harmonic drive, which is one of the key performances of harmonic reducer. Because the flexible bearing is a wave generator of harmonic reducer, its clearance has a great influence on the accuracy of harmonic drive. To obtain the influence of clearance on the backlash of harmonic reducer, the clearance of flexible bearing is equivalent to the backlash of gear teeth to carry out the theoretical value of the backlash of harmonic reducer. Then a new measuring instrument was set up to measure the backlash of harmonic reducer. The results show that the test value is larger than the theoretical value. The research finds that the torsional stiffness of the harmonic drive has non-linear characteristics. Then the hysteresis curve of the flexible bearing is drawn, and the four-segment stiffness values of the flexible bearing under different clearances are analyzed. Finally, the vibration equation is established based on the time-varying stiffness, and the calculation shows that the clearance also has influence on the natural frequency of the flexible bearing system and test results show that the rotation position has a great influence on the natural frequency.

Keywords

• backlash
• flexible bearing clearance
• hysteresis curve
• natural frequency