Apparatus for the heating of plastics material pre-forms with aeration screening capable of being dismantled

#The present invention relates to an apparatus for the heating of plastics material pre-forms. Apparatuses of this type have long been known from the prior art. In the beverage producing industry it has become customary to produce plastic bottles, in which case plastics material pre-forms pass through a furnace, in particular an infrared furnace, for this purpose and are then shaped in this heated state in a following blow moulding machine, in particular a stretch blow moulding machine, by being acted upon with blow moulding air to form the plastics material containers. In this case furnaces of this type have to heat the respective plastics material pre-forms very exactly and to a precisely defined temperature.

#In addition, it is known in this case for infrared radiators to heat the plastics material pre-forms and for the radiation to be reflected in this case by back reflectors as well as also by counter reflectors which are situated on the side of the infrared radiators arranged opposite in each case with respect to the conveying path of the plastics material pre-forms. Reflectors of this type consist in this case of ceramic material for example. It is also possible in this case for a diffuse multiple reflection to occur between these reflectors described. The long-wave portions of the infrared radiation, however, can penetrate in this case only to a poor degree into the material of the plastics material pre-forms, for example PET. This means that the surface of the plastics material pre-forms heats up more quickly than the planes of material situated at a lower level. In particular, in the case of plastics material pre-forms with a higher material strength this can lead to the surfaces thereof being excessively heated by the long-wave portions of radiation, whereas the lower-lying areas of the plastics material pre-forms are not sufficiently heated. In order therefore to be able to heat the lower-lying areas of the plastics material pre-forms sufficiently, whilst at the same time preventing the outer surface of the pre-forms from overheating and from the crystallization associated with the latter, it is known from the prior art of the Applicants to cool during the heating process.

#In addition, it is known at least from the internal prior art of the Applicants for use to be made of a surface cooling of the plastics material pre-forms which will prevent the surface of the plastics material pre-forms from overheating in such a way that a so-called thermal crystallization takes place on the plastics material pre-forms. This surface cooling of the plastics material pre-forms has the drawback, however, that more air is frequently blown onto the plastics material pre-forms than is in fact required to counteract the above effect. This, however, adversely affects the energy efficiency of the furnace since it is heated and cooled at the same time.

#In the drawings:

#FIG. 1 is a diagrammatic illustration of an arrangement according to the invention for the production of plastics material containers with a heating apparatus according to the invention, and

#FIG. 2 is a view of an apparatus according to the invention.

#FIG. 1 shows a view of a plant 70 for the production of plastics material containers. In this case a supply device 32 is first provided which supplies plastics material pre-forms 10 to a heating apparatus 1 according to the invention. The reference number 34 designates in this case a separating apparatus, such as for example a single-step star wheel, the external periphery of which has a plurality of recesses which guide the plastics material pre-forms 10 separately in each case. The apparatus 1 according to the invention has a conveying device which is designated 2 as a whole and which guides the plastics material pre-forms along their conveying path T.

#A plurality of heating devices 4 are arranged in series one behind the other in each case on the external periphery of this conveying path. The reference number 42 designates a holding element which is used for holding the individual plastics material pre-forms. As indicated by the small arrows, the plastics material pre-forms are turned in this case about their longitudinal direction in addition to their movement along the conveying path T. The reference number 22 designates diagrammatically a reversing wheel, in the region of which the conveying movement of the plastics material pre-forms is reversed by 180° and they are then guided back again.

#The reference number 56 designates a transfer wheel which takes on the now heated plastics material pre-forms and transfers them to a shaping device (not shown) arranged downstream for shaping plastics material pre-forms into plastics material containers. This apparatus for shaping plastics material pre-forms into plastics material containers is preferably a stretch blow moulding machine which has a plurality of shaping stations 52 (recognizable only in part) arranged on a movable, and in particular on a rotatable, carrier. These shaping stations in each case have receiving spaces in this case for receiving the plastics material pre-forms as well as stressing devices, such as for example blow moulding nozzles, which expand the plastics material pre-forms to form the plastics material containers by acting upon them with blow moulding air. It is also possible, however, for the pre-forms between the heating apparatus 1 and the shaping device to pass through a further apparatus, such as for example a sterilization device, in which the pre-forms can be sterilized by being acted upon with a sterilization agent, such as for example hydrogen peroxide or peracetic acid.