Fastening structure for ring-gear and differential case, and differential device using same

A fastening structure for ring gear and differential case, including:

• a ring gear having an outer peripheral surface formed with a gear section and an inner peripheral surface formed with a plurality of notch portions recessed from the inner peripheral surface;
• a differential case including a press-fit surface on which the ring gear is press-fitted and a flange portion formed at an end of the press-fit surface and pressed against the notch portions,
• the ring gear is press-fitted on the press-fit surface and then the flange portion is pressed against the notch portions to fasten the differential case to the ring gear by caulking,
• wherein the notch portions each have:
• at least two step surfaces that are flat,
• at least two slant surfaces formed to be slanted toward a notch central line of each of the notch portions in a direction recessed from the inner peripheral surface, wherein each of the slant surfaces is located between one of the step surfaces and the inner peripheral surface, and
• at least two shoulders, wherein each of the shoulders is formed between one of the step surfaces and one of the slant surfaces, and
• the notch portions are each formed with a recess on the step surfaces so that the recess is concave on an opposite side from the flange portion to release part of caulking load acting on the step surfaces into the recess.