Pinion gear unit and swivel actuator using same

A swivel actuator comprising:

• a lower housing having a hollow cylindrical portion protruding upward from a center of the lower housing, the hollow cylindrical portion serving as a support shaft of a rotor;
• an upper housing stacked and assembled on an upper portion of the lower housing and having a through hole formed in a central portion of the upper housing in which the hollow cylindrical portion protrudes upward through the through hole;
• a driving motor which is arranged on a bottom surface of the lower housing and has a rotor worm gear integrally formed on an outer circumference of a cylindrical extension unit extending to an upper portion of the rotor;
• first and second gear trains, each being arranged at intervals of 180 degrees at an outer circumference of the rotor worm gear protruding to the upper housing and being coupled to the upper housing, having, in a middle of first and second power transmission shafts, first and second worm wheels gear-coupled to the rotor worm gear, and having a first worm gear, a second worm gear, a third worm gear and a fourth worm gear formed at both sides of each of the first and second power transmission shafts;
• a first pinion gear unit, a second pinion gear unit, a third pinion gear unit and a fourth pinion gear unit in which a third worm wheel, a fourth worm wheel, a fifth worm wheel and a sixth worm wheel gear-coupled to the first pinion gear unit, the second pinion gear unit, the third pinion gear unit and the fourth pinion gear unit, respectively, are formed at the lower ends of a first support shaft, a second support shaft, a third support shaft and a fourth support shaft, respectively, and a first pinion gear, a second pinion gear, a third pinion gear and a fourth pinion gear are formed on the upper ends of the first support shaft, the second support shaft, the third support shaft and the fourth support shaft, respectively;
• and
• a rotary table having a ring gear integrally formed on an inner side of a side surface portion of the rotary table, wherein the first pinion gear, the second pinion gear, the third pinion gear and the fourth pinion gear are gear-coupled to the ring gear so as to rotate, wherein
• the third worm wheel, the fourth worm wheel, the fifth worm wheel and the sixth worm wheel and the first pinion gear, the second pinion gear, the third pinion gear and the fourth pinion gear of the first pinion gear unit, the second pinion gear unit, the third pinion gear unit and the fourth pinion gear unit are individually sintered and formed and then polygonal coupling parts of the third worm wheel, the fourth worm wheel, the fifth worm wheel and the sixth worm wheel are coupled to polygonal inner circumferences of the first pinion gear, the second pinion gear, the third pinion gear and the fourth pinion gear, respectively.