US 6,266,991 B1 · Coldwork holes with reusable seamless SMA sleeve

Abstract

A method and apparatus for coldworking holes using a reusable tubular seamless sleeve made of shape memory alloys. The apparatus uses a pre-lubricated tubular seamless sleeve made of shape memory alloys having a superelasticity property, a mandrel having a major diameter portion, an end-cap with a rough surface, and an adapting-spacer having a rough complementary surface. The preferred coldworking operation includes the steps of placing the sleeve firmly between the rough surfaces of the end-cap and the adapting-spacer which are carried on a mandrel pulling means, passing forward the major diameter portion of the mandrel through the sleeve whose diameter is therefore elastically expanded and thereafter shrinks to a size sufficiently smaller than the diameter of a hole in a workpiece, inserting the sleeve together with the mandrel into said hole, placing the end-cap against the workpiece, retracting the mandrel backward through and out of the sleeve; thereby elastically expanding the sleeve wall against the hole bore and exerting radial outward forces on the sleeve which in turn transmitting the coldworking force to the hole bore; thereafter the sleeve diameter shrinking to a size sufficiently smaller than the diameter of the coldworked hole to ease the removal the sleeve out of the hole. The sleeve is reusable due to the repeatability of the superelasticity property of shape memory alloys.

Claims22

Dependent claims

A method to coldwork holes at ambient temperatures of manufacturing shops, utilizing superelasticity property of shape memory alloys, comprising the steps of:

(a) inserting a seamless sleeve made of a shape memory alloy having a superelasticity property into a hole in an associated workpiece, whose diameter is sufficiently larger than the outside diameter of said sleeve;
(b) placing a mandrel having a diameter at one end sufficiently larger than the inside diameter of said sleeve, the combined diameter of said mandrel and wall thickness of said sleeve being greater than the diameter of said hole;
(c) driving said end of said mandrel through and out of said sleeve to expand said sleeve and said hole, thereby coldworking the material around said hole;
thereafter said sleeve at ambient temperature shrinking to an outside diameter sufficiently smaller than the diameter of coldworked said hole as to ease the removal of said sleeve out of coldworked said hole.

1 more element

An apparatus for coldworking holes in an associated workpiece using tubular seamless sleeves made of a shape memory alloy with a superelasticity property in conjunction with its operation comprising in combination:

(a) a cylindrical-shaped mandrel having a major diameter portion and a minor diameter portion;
(b) a tubular seamless sleeve made of a shape memory alloy, having a tubular portion;
a shoulder portion, and a fillet radius joining said tubular and said shoulder portions;
(c) said sleeve to be used as a means during coldworking operation for receiving exerted expansion forces from the major diameter portion of said mandrel while simultaneously adapted to carry said forces in a radial direction to the inside surface of a hole in an associated workpiece for enlarging said hole and putting the material around said hole in compression to improve fatigue property of said hole;
(d) an end-cap having a central circular passageway and a rough surface for complementing and seating the shoulder of said sleeve and for securing, in conjunction with a spacer, said sleeve;
(e) a spacer having a central circular passageway and a rough surface at one end for complementing the shoulder of said sleeve and for securing, in conjunction with said end-cap, said sleeve;
(f) a bearing to sufficiently firmly seat said spacer;
(g) an adapter to sufficiently firmly seat said bearing at one end, and to be assembled onto an extension-tube at the other end;
(h) an extension-tube to be assembled onto said adapter at one end, and to be assembled onto the cylinder of a mandrel pulling means at the other end.

6 more elements

Dependencies are inferred from the claim text.

Coldwork holes with reusable seamless SMA sleeve

Life of this patent

Coldwork holes with reusable seamless SMA sleeve

Life of this patent

Abstract

Claims22