Diagnosis and Countermeasures of vertical roller mill sound change under normal circumstances, the sound emitted by the vertical roller mill during normal operation mainly comes from the sound of mutual impact between the transmission mechanism itself and the steel ball, ore and lining plate in the cylinder.The strength of the impact sound in the cylinder will change with the different materials in the mill. When it is found that the sound begins to become dull, it is mostly due to the "belly swelling" of the vertical roller mill, which leads to the sound change.In serious cases, there is almost no sound in the cylinder, only the buzzing sound from other places is heard.There are many reasons for the "belly swelling" of the vertical roller mill, such as excessive ore feeding and increased amount of large stones, resulting in low passing rate and indigestion of the vertical roller mill; The water pressure at the feeding end becomes smaller and the water supply is insufficient, resulting in the increase of grinding concentration, the slow flow rate of minerals in the mill and poor ore discharge; Or the ball feeding amount of the vertical roller mill is incorrect.