METHOD AND STRUCTURE FOR FIXING INTERNAL GEAR OF PLANETARY SPEED REDUCTION GEAR, AND PLANETARY SPEED REDUCTION GEAR

PROBLEM TO BE SOLVED: To provide a method and structure for fixing the internal gear of a planetary speed reduction gear, and a planetary speed reduction gear, achieving the design of specifications of a high-strength gear since there are no accuracy deterioration caused by press-fitting and an influence of misalignment, high accuracy can be maintained, and the diameter of the internal gear is increased, by forming a gear case and the internal gear in an integral structure.SOLUTION: In this method for fixing the internal gear of the planetary speed reduction gear and the gear case, when performing the die-cast molding of the gear case 10, the die-cast molding of the gear case 10 is performed after an alloy steel annular internal gear blank 15A is inserted into the die of the gear case 10. Thereby, the internal gear blank 15A is fixed to the gear case 10. Then, the inner peripheral surface of the internal gear blank 15A is applied with gear machining, and the internal gear 15 is attached to the inner peripheral surface of the gear case 10.