In order to prevent the sand belt from deviating from the original normal position along the core wheel axis during off-speed operation, the outer 圔 cylinder of the idler wheel should have a certain drum degree.

However, the tension force borne by the middle part of the sand belt is larger than that on both sides, and the middle part of the sand belt is worn greatly during processing, which affects the accuracy of the workpiece. This problem is very prominent when grinding with wide abrasive belt or high precision abrasive belt. Therefore, in order to solve this problem, the wide abrasive belt grinder or off-tip abrasive belt grinder is equipped with sand belt vibration selection fee, so that the abrasive belt moves reciprocating along the idler axis within a certain range, so that the abrasive grain on the abrasive belt not only cuts the workpiece in the direction of the main movement, but also produces cutting effect in the direction perpendicular to the main movement.

In this way, the wear of each part of the sand belt is more uniform, and the machining tip of the workpiece is also improved and the surface roughness is reduced due to the composite movement of the sand belt.