Patent ID: 7553156

Claim:
A furnace ( 22 ) for heating a preform ( 10 ), which comprises: a longitudinal heating tunnel ( 24 ) bounded transversely by mutually parallel longitudinal vertical internal faces ( 36 , 38 ) of two walls ( 40 , 42 ), one a heating wall ( 40 ), being equipped with a heating system ( 46 ), and the other an aerated wall ( 42 ), having aeration orifices ( 50 ), and in the heating tunnel ( 24 ), a first portion ( 12 , 14 ) of the preform ( 10 ) is heated, while a second portion ( 16 ) of the preform ( 10 ) is held outside the heating tunnel ( 24 ) through a longitudinal opening ( 41 ) made between longitudinal edges of the walls ( 40 , 42 ) of the heating tunnel ( 24 ); a blower ( 52 ) which includes a first fan ( 54 a ) and a second fan ( 54 b ) said first fan ( 54 a ) delivers a first air stream transversely in a first delivery duct ( 60 a ) from an upstream, outside the heating tunnel ( 24 ), to a downstream, inside the latter, in a direction of the first portion ( 12 , 14 ) of the preform ( 10 ), by passing through the aerated wall ( 42 ); said second fan ( 54 b ) delivers a second air stream transversely which is parallel to the first air stream, in a second delivery duct ( 60 b ) from the upstream, outside the heating tunnel ( 24 ), to the downstream, directly to the second portion ( 16 ) of the preform ( 10 ), so as to keep the constituent material of this second portion ( 16 ) of the preform ( 10 ) at a temperature below its softening point; and the two separate air delivery ducts ( 60 a , 60 b ) being adjacent and formed by the upper and lower compartments of a common box ( 66 ) having a dividing partition ( 68 ).