Abstract: By analyzing the problem of the ripping sound of drum washing machine at 1120 r/min, through mechanism research, its essence is a beat vibration phenomenon. On the basis of mechanism research, according to the characteristics of noise performance, analysis of excitation source, the belt pulley produced by the third harmonic excitation and motor bearing damage caused by 3.1 times of frequency excitation force interaction is the main cause of the problem. The problem was diagnosed and controlled from the optimization of belt structure and roundness of inner and outer raceway of bearing, the test results showed that the problem of the ripping sound was effectively improved. The accuracy of mechanism analysis is verified and theoretical guidance is provided for solving the ripping sound of drum washing machine completely.

Key words: Drum washing machine, Rippling sound, Beat, Bearing roundness