Patent ID: 6629708
Filing Date: 2003-10-07
Classification: F16L

Abstract:
A tube fitting comprising: a fitting body having a cylindrical bore for receiving a tube end and including a tapered mouth at one end of said bore; a drive member having a threaded engagement with said body and having a ferrule drive surface; a first ferrule having a tapered first end that extends into said tapered mouth of the fitting body and having a second end with a tapered recess forming a camming surface that axially extends toward said first end; and a second ferrule having a generally cylindrical interior wall, a tapered first end that extends into said tapered recess and engages said camming surface of said first ferrule, a tapered outer wall portion, and a driven surface on a second end thereof that engages said drive member ferrule drive surface; said second ferrule interior wall having a first circumferential recess located between said first and second ends of said second ferrule; said tapered wall portion having a second circumferential recess near said first end; wherein said second ferrule driven surface comprises a contoured face and that with said first and second circumferential recesses produce a radial component in pull up forces occurring at said drive surface to distribute more uniformly said pull up forces across an interface area between said drive surface and said contoured face as compared to force concentration areas that would otherwise be present at said interface area in absence of said contoured face and said first and second circumferential recess.