CRYOGENIC MANDREL EXPANSION

摘要

Described herein are improved methods and means for lubrication during diametral mandrel expansion of hollow couplings at cryogenic temperatures, the couplings being formed of a metal susceptible to the impartation of dimensional heat recoverability by deformation at a temperature below that at which the material undergoes a martensitic transformation. Films or fibrilous cloths of organic material are disposed between the interior wall of the part and the mandrel, the material being such as to undergo plastic deformation at the temperatures and pressures obtained during forcible expansion of the fitting internal diameter of from about 3 to about 9 percent, in order to provide roller bearing lubrication. Preferred lubricant materials are polyethylene and related linear polymers and waxes and fluorocarbon oligomers. The couplings may be formed of titanium-nickel or beta-copper alloys, stainless steels and the like.