Patent ID: 6364588
Filing Date: 2002-04-02
Classification: F16B

Abstract:
A structure of a nut internal thread portion for preventing looseness, wherein an exit end portion of an internal thread portion of the nut is taperingly contracted on the entire circumference thereof; wherein the nut has smaller minor diameters of internal thread than a middle portion,wherein ridges of the contracted internal thread portion are provided in the form of a circumferentially continuing corrugation which has a plurality of projections projecting toward the center of the contracted internal thread portion and which has depressions depressed away from the center of the contracted internal thread portion, wherein circles inscribed by the plurality of projections are gradually smaller towards an exit side hole; wherein, when the nut is adapted to engage an external-thread member with the internal thread portion, the plurality of projections in the corrugation of the ridges of the contracted internal thread portion press roots or flanks of the external-thread member and are thereby elastically compressed, so as to clamp the external-thread member wherein the number of the threads provided with the corrugation is not less than two and not more than four, and wherein the number of the projections in the corrugation is within the range from 10 to 14.