Electronic drill with revolving replaceable drilling heads

An electronic drill with revolving replaceable drilling heads, comprising:

• a housing having a front end and a rear end, the housing comprising:
• an opening located at the rear end;
• a through hole located at the front end;
• a containing room connected between the opening and the through hole, the containing room having a groove disposed at an inner wall and extending to correspond to the through hole;
• a motor container disposed within the containing room with a rotary track defined between the motor container and the inner wall of the containing room, the rotary track surrounding the motor container;
• a driving unit, comprising:
• a motor disposed in the motor container:
• and
• a gear set disposed outside the motor container and driven by the motor and having a rotary hole in connection with the through hole;
• a rotary cover detachably assembled to the rear end of the housing and covering the opening, the rotary cover comprising a wheel rotatable with respect to the housing and comprising at least two hollow recesses;
• and
• a plurality of drill heads, each drill head detachably coupled to one of the recesses and directed toward the rotary track and having a protrusion adapted to correspond and slide in the groove;
• wherein the drill heads move freely in the rotary track as the wheel rotates with respect to the housing;
• wherein as one of the drill heads aligns with the rotary hole, the drill head is slidable in the groove with its protrusion and passes through the rotary hole and the through hole, so as to be engaged with and rotated by the rotary hole.