Ovens for preforms

A system for blowing or stretch-blowing plastic material, comprising an oven for heating and curing the heat profile of preforms,

• a blowing or stretch-blowing machine, comprising a plurality of mould and drive units of the preforms entering and exiting said oven, wherein said oven comprises units of transport devices and heating sources for the preforms, wherein said transport devices comprise a track on which a plurality of mandrels individually slide, each adapted for engaging a preform, and wherein said drive units for the preforms coming out of the oven, comprise a plurality of gripping members for the preforms distanced at a fixed pitch substantially equivalent to the pitch of the moulds, wherein said oven comprises drive and distancing units of the heated preforms from a minimum pitch to a pitch substantially corresponding to the pitch of the gripping members of the drive units for the preforms coming out of the oven, wherein said drive and distancing units of the preforms comprise a first screw positioned at the feed point of the preforms into the oven, between the second conductor wheel and a first rectilinear section of the track, and a second screw positioned at a junction point between the second rectilinear section of the track and said conductor wheel.