Device and method for thermally conditioning preforms
The invention relates to a heat box for thermally conditioning preforms ( 10 ) that consist of a thermoplastic material and are provided for blow moulding, in which two lateral walls ( 32 ) and one base wall ( 34 ) delimit a heat tunnel through which the preforms ( 10 ) are conveyed, said heat tunnel comprising at least two parallel heat channels, and a heating unit ( 14 ) being arranged between two adjacent, particularly parallel heat channels and comprising a plurality of rod-shaped heating elements ( 16 ) that extend longitudinally in the conveyor direction of the preforms ( 10 ).
1. A heat box for thermally conditioning preforms made of thermoplastic material for blow molding, said heat box comprising two opposing side walls and one bottom wall that together define a heating tunnel, and wherein:
the heating tunnel comprises at least two separate heat channels that extend parallel to one another and through which the preforms are transportable in a transport direction;
a heating unit is arranged between the at least two separate heat channels;
the heating unit comprises a plurality of rod-shaped heating elements that extend longitudinally in the transport direction of the preforms;
the heating unit comprises two hollow columnar carrier elements that hold the plurality of heating elements;
each of the carrier elements is open on each end;
the carrier elements define a shaft that functions as a conduit for a flow of fluid through the carrier elements;
a cooling conduit is arranged underneath the heat box; and
the cooling conduit is fluidly connected to the shafts of the carrier elements.
2. The heat box according to claim 1 , wherein the heating unit further comprises at least one web-shaped radiation shield which extends longitudinally between two adjacent heating elements.
3. The heat box according to claim 1 , wherein each end area of the plurality of rod-shaped heating elements is held by the carrier elements in such a manner that free ends of the heating elements extend into the shafts defined by the carrier elements.
4. The heat box according to claim 1 , wherein each of the rod-shaped heating elements of a heating unit is connected in an electrically conductive manner to a common plug contact.
5. The heat box according to claim 1 , wherein the heating units are modular and are individually removable from the heat box.
6. The heat box according to claim 1 , wherein each of the carrier elements comprises a cover element that is removable to provide lateral access to the shaft.
7. The heat box according to claim 1 , wherein end areas of the heating elements comprise holding bodies that are positively insertable into receiving openings of the carrier elements.
8. The heat box according to claim 7 , wherein the receiving openings are arranged as sequential laterally open slide-in units into a wall area of the carrier elements.
9. The heat box according to claim 8 , wherein the wall areas with the receiving openings are movably supported on the carrier elements to adjust a height of the heating elements relative to the heat tunnel.
10. The heat box according to claim 1 , wherein said two opposing side walls of the heat box comprise elements for reflecting thermal radiation.
11. The heat box according to claim 1 , further comprising transport means for transporting the preforms in a single row through the at least two separate heat channels in in opposite directions.
12. A heating device comprising a plurality of heating boxes according to claim 1 , wherein said heat boxes are arranged side by side so as to form a heating section.
13. A blowing machine comprising a heat box according to claim 1 .
14. A method for thermally conditioning preforms made of thermoplastic material for blow molding, comprising moving in adjacently running transport rows through a heat box according to claim 1 , wherein the transport rows run through the separate heat channels of the heat box, and wherein the heating element arranged between the separate heat channels heats the thermoplastic material of the preforms guided past the heating element on both sides.
15. The method according to claim 14 , wherein the preforms are transported in opposite directions through the separate heat channels of the heat box.