The utility model discloses a motor -driven hank grinds protection casing is connected with the fixed bolster by the shell body and constitutes, the shell body comprises arch section and long rod shaped part, is convenient for wrap up in interior flexibly twisting the mechanical rotary mechanism who grinds. The fixed bolster comprises a plurality of right angles type flap, be provided with the mounting hole on the right angle shape flap, with the assembly screw looks adaptation on the motor -driven hank mill, right angle type flap welds respectively the tip or the middle part of shell body. The shell body all adopts the welding of 0.6mm galvanized steel sheet, riveting to form with the fixed bolster, and processing is simple, low cost. The utility model discloses can be convenient install and remove, the field usage of being convenient for, processing is simple, low cost. The protection casing wide coverage can effectively be avoided the rotating part to expose and hurt sb. 's feelings. Protection casing intensity satisfies the operation requirement, moves the in -process at machinery and the condition such as collapse does not appear warping.