US 6,742,376 B2 · Method and apparatus for manufacturing structures with improved fatigue life

Abstract

A compound indenter for metal coldwork, and a method of employing such tooling. The compound indenter tool is used to produce deformation in a workpiece structure, to provide a selected beneficial residual stress profile in the workpiece, in order to provide high fatigue life structures in a minimum number of manufacturing steps. Preferably, action of a compound indenter causes deformation of the workpiece, causing dimples in the workpiece. By optimized use of the method, a relatively uniform beneficial residual stress profile is provided at both the surface and at the midplane apertures in a workpiece, so as to improve overall fatigue life. An improved, compound indenter tool profile shape is described, having a first, elongate indenter with a shaped indenter surface portion, and a second shaped indenter surrounding the first indenter and forming an annular shoulder recessed from the surface portion of the first indenter. Additionally, a foot having a bottom portion can be used to confiningly surround the second indenter during application of force to the surface of a workpiece, to prevent surface deformation.

Claims66

Dependent claims

Tooling for working a structure to improve the fatigue strength at a selected location in said structure, said structure comprising a first surface, a second surface, and a body having a thickness therebetween, said tooling comprising:

(a) a first primary indenter, said first primary indenter comprising a contacting end for engagement with and deformation of a pre-selected portion of said first surface of said structure to a preselected depth to impart a beneficial residual compressive stress profile within said body of said structure effective for improving fatigue life of said structure;
(b) a first secondary indenter, said first secondary indenter comprising a contacting end for engagement with and deformation of a pre-selected portion of said first surface of said structure to a preselected depth to impart a beneficial residual compressive stress profile in said body of said structure effective for improving fatigue life of said structure;
(c) wherein said contacting end of said first primary indenter comprises a first shaped surface having a preselected profile, and wherein said contacting end of said first secondary indenter comprises a second shaped surface having a preselected surface profile, and wherein said first primary indenter and said first secondary indenter are configured for engagement with said first surface of said structure;
(d) said first primary indenter and said first secondary indenter configured to impart a residual compressive stress substantially uniform through the entire thickness of the body of said structure.

1 more element

Dependencies are inferred from the claim text.

Method and apparatus for manufacturing structures with improved fatigue life

Life of this patent

Method and apparatus for manufacturing structures with improved fatigue life

Life of this patent

Abstract

Claims66