Automatic valve grinder

The utility model relates to an automatic valve grinder comprising a housing, a spring pre-tightening knob, a spring pre-tightening screw, an upper piston, a spring, a lower piston, guide rods, a step motor, a sucker and a support frame. The housing is internally provided with a hollow cavity and is fixed to the support frame. The bottom end of the housing is provided with an air inlet and an air outlet. The upper piston, the spring and the lower piston are arranged within the housing. The spring pre-tightening screw penetrates the top end of the housing; one end of the spring pre-tightening screw is connected with the spring pre-tightening knob; the other end of the spring pre-tightening screw is connected with the upper piston; one end of the spring is connected with the upper piston; the other end of the spring is connected with the lower piston. The upper piston is provided with an air hole. One end of every guide rod is connected with the lower piston; the other end of every guide rod is fixed to the step motor; the sucker is rotatably fixed on the step motor. The automatic valve grinder has the advantages that valve grinding efficiency and valve grinding quality are greatly improved, and engine repair costs are reduced.