초록 ▼

A noncircular opening is formed in a material. A mandrel or mandrel and expansion sleeve are used for coldworking a circular region of the noncircular opening, and for forcing a hard metal insert into coldworking contact with the material immediately bordering the remaining portion of the noncircula

A noncircular opening is formed in a material. A mandrel or mandrel and expansion sleeve are used for coldworking a circular region of the noncircular opening, and for forcing a hard metal insert into coldworking contact with the material immediately bordering the remaining portion of the noncircular opening. An insert may be placed within a slot to form with a circular closed end of the slot a substantially circular opening. An expansion sleeve is placed in the opening and an expansion mandrel is pulled through it, or an expansion mandrel is used alone in the opening, to coldwork the circular region of the opening. An insert may be placed within an opening and then a mandrel moved through an expansion sleeve placed in a circular opening in the insert, or a mandrel alone may be moved through the opening, to radially expand the insert and coldwork the material bounding the noncircular opening.

대표청구항 ▼

A method of coldworking material bounding a circular region of a noncircular opening in the material, said method comprising: inserting into the opening adjacent the circular region of the opening a hard metal insert having a concave surface, with said concave surface of the hard metal insert and sa

A method of coldworking material bounding a circular region of a noncircular opening in the material, said method comprising: inserting into the opening adjacent the circular region of the opening a hard metal insert having a concave surface, with said concave surface of the hard metal insert and said circular region of the opening together defining a substantially circular opening; positioning a generally tubular cold-expansion sleeve onto a reduced diameter intermediate portion of a cold-expansion mandrel, said mandrel including an increasing diameter portion axially outwardly of said intermediate portion, and a maximum diameter portion axially outwardly of said increasing diameter portion; inserting the mandrel and the sleeve into the substantially circular opening from one side of the material; holding said sleeve and said hard metal insert within said opening; and retracting the mandrel through the sleeve, so that as the mandrel is retracting the increasing and maximum diameter portions of the mandrel expand the sleeve radially to prestress the circular region of the material immediately contacted by said sleeve.