Filament draw nozzle

A filament draw nozzle comprising, in combination:

• means defining a throughbore, and including an upwardly projecting annular boss, said boss having a cylindrical peripheral wall leading to a generally smoothly curved surface extending to said throughbore;
• a housing defining an aperture and including an inner wall curving downwardly and leading to said aperture, said housing being positioned in engagement with said throughbore defining means with said housing aligned relative to said throughbore defining means to define a pressurizable annular air cavity therewith, said housing inner wall and said generally smoothly curved surface defining an annular downwardly directed slit providing communication between said air cavity and said throughbore whereby pressurized air in said cavity passes through said slit to said throughbore and downwardly along said generally smoothly curved surface;
• and
• fiber inlet defining means including a cylindrical fiber feed tube having an outer wall selectively removably positionable in said housing aperture with said outer wall bearing against said housing, said throughbore and said housing aperture being disposed in alignment whereby said fiber feed tube when positioned in said aperture is concentrically disposed relative to and within said throughbore and defines with said generally smoothly curved surface a supersonic nozzle, said slit and said generally smoothly curved surface defining a Coanda nozzle directing and maintaining air flow in a downward direction through said throughbore and said housing aperture when said fiber feed tube is removed from said housing aperture.