Heating device for machines for the transformation of plastic materials

Machine (12) fore transforming plastic material, comprising, arranged along a guide track (24), a heating device (10) adapted to coact with at least one row of preforms (14) carried by supports (17) moved through the heating device (10), this latter having a heating body (39) arranged facing the preforms (14), characterized by the fact that the heating body (39) comprises at least two heating tubes (40) each containing a bidirectional heating blade (54) adapted to emit heating radiation to two opposite sides, the preforms being disposed in at least two parallel rows of preforms in the heating device (10), the two tubes being adapted to be arranged between the two parallel rows of preforms to form a heating body of which each of the heating blades (54) is inclined at a predetermined angle (.alpha.) relative to a vertical plane such that a first of these surfaces emits heating radiation (55) in the direction of the adjacent row of preforms and such that the second surface emits heating radiation (56) toward the farther row of preforms substantially in the direction of the free space between the opposite heating tube or tubes.