Patent ID: 6508093
Filing Date: 2003-01-21
Classification: B24B,C21D,F01D,Y10T

Abstract:
A method of surface treating and compressively prestressing by peening a wall of at least one annular recess approximately in the shape of a dovetail, formed in the periphery of a rotor rim, said annular recess opening to the outside via an annular lateral mouth and having at least two recess ends opening into, respectively, at least one blade introduction opening, said method comprising the steps of:a) providing a sonotrode arranged within a sleeve, said sonotrode having a vibratory surface and ultrasonic means for vibrating said vibratory surface, and said sleeve having opposed closing-off means capable of sliding in the recess; b) placing a plurality of beads of a predetermined diameter on said vibratory surface of said sonotrode with said sonotrode arranged in an intermediate position in which said sleeve surrounds said vibratory surface; c) placing said introduction opening facing said sonotrode; d) moving said sonotrode together with said sleeve substantially vertically toward said blade introduction opening to place them in a peening position in which said closing-off means face said recess ends that open into said opening; (e) turning said rotor rim about an axis of rotation arranged horizontally in such a way as to bring said closing-off means into a first recess end so as to form a closed moving chamber containing said beads; and f) operating said ultrasonic means to vibrate said vibratory surface of said sonotrode whereby said beads are mobilized in said moving chamber, and, by uniformly turning said rotor rim about said axis of rotation until said second recess is reached, ultrasonically peening the entirety of said wall of said recess.