Closed carbon brush grinding tool

The invention relates to the field of electric power overhaul, in particular to a closed carbon brush grinding tool. The closed carbon brush grinding tool is applied to the carbon brush replacing and grinding work of a stator sub-ring in a maintenance process of a water-turbine generator set. The closed carbon brush grinding tool comprises a dust collection box, wherein a driving wheel, a first driven wheel, a second driven wheel and a third driven wheel which are in transmission connection through an abrasive belt are arranged in the dust collection box, a plane grinding module is fixed between the driving wheel and the first driven wheel, and a plane grinding opening is formed in the upper surface of the dust collection box corresponding to the plane grinding module; an arc-shaped plane grinding module is arranged between the first driven wheel and the second driven wheel; the center of the third driven wheel is connected with a locking mechanism for adjusting the tightness of the abrasive belt; a carbon br