Abstract:
An apparatus for the conditioning of plastics material pre-forms with a tempering space for receiving a plurality of plastics material pre-forms, with a supply device a removal device, and a conveying device which conveys the plastics material pre-forms from the supply device to the removal device in such a way that each plastics material pre-form remains in the tempering space for a preset duration of the dwell period. The temperature of the plastics material pre-forms upon leaving the removal device is substantially constant irrespective of a duration of the dwell period of the plastics material pre-forms in the tempering space and the conveying device is designed in such a way that each plastics material perform remains in the tempering space for a period of time of at least five minutes.

Description:
The present application claims priority from German patent application number 10 2010 049 404.6 filed Oct. 26, 2010, which application is hereby incorporated herein by reference for all purposes. 
     The present invention relates to an apparatus and a method of producing plastics material containers. Apparatus and methods of this general type have long been known from the prior art. In this case plastics material pre-forms are usually first heated in a furnace and are then shaped to form plastics material containers by means of a blow molding device, such as for example a stretch blow molding machine. Problems arise for example if problems arise in a unit, such as for example a labelling machine, arranged downstream of the shaping device, and if the shaping procedure has to be interrupted. An interruption of the conveying of the plastics material pre-forms by the heating device can lead to individual plastics material pre-forms becoming overheated and being destroyed in this way. In addition, plastics material pre-forms once heated in the heating device cannot be cooled again and heated a further time, and so these plastics material pre-forms go to waste. 
     A pre-treatment of plastics material pre-forms before a blow molding procedure is known from EP 0 736 367 B1. In this case a pre-conditioning unit is provided which is traversed by the plastics material pre-forms and which is arranged in such a way that exactly the same heat is introduced into each plastics material pre-form. In this case, during the conveying, the plastics material pre-forms are put in groups of three in each case onto conveying units and are conveyed through the pre-conditioning unit with these conveying units. In this way it can be made possible in a very short time for the plastics material pre-forms to be at substantially the same temperature. 
     Nevertheless, the apparatus described in EP 0 736 367 B1 is relatively complicated technically and, in particular, the conveying system is relatively expensive. 
     DE 10 2008 014 215 A1 describes an apparatus for heating plastics material pre-forms. In this case the plastics material pre-forms are first pre-heated in order to be subsequently heated again in a more energy-efficient manner with a microwave heating device. 
     A magazine for pre-forms is known from DE 30 20 150 C2. This magazine has a closed housing with vertical lateral walls, and openings for the introduction of hot air kept at a constant temperature by means of a temperature regulating device in order to pre-heat the plastics material pre-forms in a heating zone of the magazine. 
     The object of the present invention is to make available a facility for the conditioning of plastics material pre-forms, which also permits a uniform heating or conditioning of the plastics material pre-forms even at the most widely varying starting temperatures of the latter. 
     In addition, it should be possible for this conditioning to be carried out irrespectively of whether the plastics material pre-forms arrive at the conditioning device starting from a production device or starting from very low or very different initial temperatures. 
     SUMMARY OF THE INVENTION 
     An apparatus according to the invention for the conditioning, in particular the thermal conditioning, of plastics material pre-forms has a tempering space for receiving a plurality of plastics material pre-forms as well as a supply device in order to supply the plastics material pre-forms to the tempering space. In addition, the apparatus has a removal device in order to move the plastics material pre-forms out of the tempering space, as well as a conveying device which conveys the plastics material pre-forms from the supply device to the removal device in such a way that each plastics material pre-form remains in the tempering space for a pre-set duration of the dwell period. 
     According to the invention a temperature of the plastics material pre-forms leaving the removal device is substantially constant irrespective of a duration of the dwell period of the plastics material pre-forms in the tempering space and the conveying device is designed in such a way that each plastics material pre-form remains in the tempering space for a period of time of at least 5 minutes. 
     Whereas reference is made in EP 0 736 367 B1 mentioned above to the fact that the plastics material pre-forms are conditioned only over a relatively short period of time such as from one and a half to two minutes, it is proposed in the scope of the present invention that this period of time should be extended to at least 5 minutes. It is advantageous for the plastics material pre-forms to remain inside the tempering space for a period of time of at least 7 minutes, in an exemplary manner of at least 10 minutes, in a particularly exemplary manner of at least 12 minutes, and in a still more particularly exemplary manner of at least 15 minutes. 
     On account of this period of time, which is considerably increased as compared with the prior art, it is made possible for the pre-forms leaving the apparatus to be at the same temperature in each case, irrespectively of how long they have remained individually inside the tempering space and also at which initial temperature they were supplied to the tempering space. This is true even if the initial temperatures are considerably different. In addition, it is possible in this way for the apparatus for conditioning also to be used as a buffer for the plastics material pre-forms since no further damage to the plastics material pre-forms occurs even in the case of considerably longer times of the duration of the dwell period. 
     In this way, it is desirable for the apparatus for conditioning, as described here, also to allow an injection molding machine for producing plastics material pre-forms to be coupled to a stretch blow molding machine, in which case the apparatus according to the invention performs four tasks to this end, namely firstly to bridge the path between the injection molding machine and the stretch blow molding machine, in addition to rectify clock-timed to continuous running, in addition to maintain an energy and heat level and finally possibly also to decouple in the event of failure of one of the two machines. 
     To this end the apparatus according to the invention mentioned above advantageously has a tempered conveying system or a conveying device which in a particularly exemplary manner has a separation means and a supply channel. These plastics material pre-forms can be supplied by way of the supply device and the tempered plastics material pre-forms can be removed by way of the removal device. 
     In addition, a feedback unit can also be provided which feeds superfluous plastics material pre-forms for example back into an inlet again. In this way, as mentioned above, the system is designed in such a way that the plastics material pre-forms have a long duration of the dwell period in the tempering space or in the tempering region, which in constant operation is at least 5 minutes, or at least 6 minutes, or at least 8 minutes, and in a particularly exemplary manner at least from 10 to 15 minutes, in which case the duration of the dwell period can be dependent upon a dimension and/or a throughput of the tempering region. This has the consequence that, independently of the temperature at which the plastics material pre-forms arrive in the tempering space and irrespective of how long they are in it, they can be delivered at always approximately the same temperature and thus enter always at the same temperature a blow molding machine arranged downstream. 
     In this case the deviation from the nominal temperature depends upon the duration of the dwell period and the flow speed in the tempering space, as well as, in addition, the entry and exit temperatures. The apparatus is designed in such a way (in particular with respect to the dimension and the conveying speed of the conveying device) that the duration of the dwell period is at least so long that even in the event of a pronounced fluctuation of the entry temperature there is only a slight deviation at the outlet. A deviation in the range of +/−0 degrees would be ideal, but this would theoretically involve a residence time of infinite length in the tempering space. 
     For a deviation in the range of +/−2 degrees, depending upon the marginal conditions a duration of the dwell period of from 10 to 25 minutes is necessary (in this case a hot air throughput of at least 500 m 3 /h, or between 800 and 2,000 m 3 /h is taken as a basis and as high a flow speed as possible (of the air to be heated or tempered) of up to 15 m/s. 
     In the case of an exemplary embodiment the temperature of the plastics material pre-forms leaving the removal device is substantially independent of a temperature of the plastics material pre-forms supplied to the tempering space by way of the supply device. This too, as mentioned above, is attained by way of the relatively long duration of the dwell period of the plastics material pre-forms. In this case “substantially independent” is to be understood as being that the temperatures of the individual plastics material pre-forms differ from one another by not more than 6K, or by not more than 5K, or by not more than 4K, or by not more than 3K, and in a particularly exemplary manner by not more than 2K. 
     In the case of an advantageous embodiment the conveying device conveys the plastics material pre-forms non-sorted at least locally through the tempering space. This is to be understood as being that the plastics material pre-forms are conveyed for example in bulk through the tempering space. It is desirable, however, for the conveying to be carried out in such a way that the longitudinal directions of the plastics material pre-forms conveyed non-sorted are orientated in more than one direction and in an exemplary embodiment are distributed in a substantially statistical manner. As a result, a considerable simplification of the apparatus is achieved and, in addition, the apparatus can also act as a buffer store for the plastics material pre-forms in this way. 
     In the case of a further advantageous embodiment the apparatus has a flow generation device which in the tempering space generates an air flow with which it is possible to act upon the plastics material pre-forms. This flow generation device can be for example fans and the like which generate a directed flow of the air or in general a gaseous medium inside the apparatus according to the invention. It would also be possible for sterile air or even a sterilization gas, which not only thermally conditions but also sterilizes the plastics material pre-forms, to be used instead of conventional air. 
     The time required for the thermal conditioning is reduced by the generation of the air flow. 
     In the case of a further advantageous embodiment the apparatus has a sensor device for determining a temperature inside the tempering space. In particular, in this case the sensor device determines a temperature of the air situated in the tempering space. In addition, a regulating device can be provided which also permits a setting of this temperature inside the tempering space. 
     In the case of a further advantageous embodiment the apparatus has conveying regions extending adjacent to one another. In this way, it is possible for the apparatus according to the invention or the tempering space respectively to be made comparatively small. In this case these conveying regions can be made laterally adjacent to one another and/or offset vertically or even in a spiral shape. In this way it would be possible for a plurality of conveyor belts to be arranged inside the tempering space and for the plastics material pre-forms to drop or move in some other way from one conveyor belt to the next conveyor belt. In particular, the conveying device does not extend along a straight line inside the tempering space. 
     In the case of a further advantageous embodiment the conveying device has a conveyor belt on which the plastics material pre-forms are conveyed through the tempering space. In addition, a plurality of conveyor belts can also be provided, for example conveyor belts—in particular thermally insulated—which are arranged one above the other and which are acted upon with hot air in a regulated manner. In this case these conveyor belts can be designed in such a way that it is also possible for the plastics material pre-forms to be acted upon with hot air from below. It is possible for all the conveying units or only individual conveying units of the conveying device to be fed with one or more tempering devices. This can be carried out for example in a manner dependent upon an initial temperature of the plastics material pre-forms on the supply device. 
     The present invention further relates to a plant for the treatment of plastics material pre-forms with an apparatus of the type described above, as well as an apparatus—arranged downstream of this apparatus in a conveying direction of the plastics material pre-forms—for shaping the plastics material pre-forms to form plastics material containers. In this case a first heating device for heating the plastics material pre-forms is arranged between the apparatus for shaping the plastics material pre-forms and the apparatus for the conditioning as described above. 
     This heating device can be for example a furnace which heats the plastics material pre-forms to a temperature which is suitable for shaping the plastics material pre-forms. In contrast, the temperature which is reached in the apparatus for the conditioning according to the invention is for example considerably below this temperature, i.e. a temperature which is for example in the range of between 30° and 70°, or between 40° and 60°, and in a particularly exemplary manner between 45° and 55°. It is desirable that the temperature to be below the glass transition temperature of the material of the plastics material pre-form and desirably at least 5° below the glass transition temperature. In this way, it is possible, even if the plastics material pre-forms are not subsequently shaped to form plastics material containers after leaving the apparatus for the conditioning, for them to be capable of being used again. 
     In the case of an advantageous embodiment the apparatus has a connecting line which conveys heated air from the heating device and/or the apparatus for shaping the plastics material pre-forms to form plastics material containers to the apparatus according to the invention. In this case in this embodiment the apparatus according to the invention is advantageously operated with the waste air of at least one of the two plants named above. 
     In the case of a further advantageous embodiment the plant according to the invention has a production device for producing the plastics material pre-forms. This can be for example an injection molding machine which produces the plastics material pre-forms from a raw mass. In this case it is advantageous for this apparatus for producing plastics material pre-forms to be arranged immediately upstream of the apparatus according to the invention. It is desirable for the conditioning apparatus according to the invention to be capable of being optionally equipped by the production device or by a reservoir with plastics material pre-forms. If the plastics material pre-forms, starting from a production device, arrive at the apparatus according to the invention, they are generally at a higher temperature than is present in the tempering space mentioned above. In this case the apparatus according to the invention is used as a cooling device for the plastics material pre-forms. 
     It would additionally be possible for a further heating device, through which the plastics material pre-forms are likewise conveyed and in which the plastics material pre-forms are tempered to a precise uniform temperature, to be provided between the apparatus for conditioning according to the invention and the heating device mentioned above. 
     The present invention further relates to a method of producing plastics material containers, in which plastics material pre-forms are heated and are then shaped in a shaping device to form plastics material containers and in which the plastics material pre-forms are conditioned thermally before the heating. In this case the plastics material pre-forms are conveyed by means of a conveying device through a tempering space to the apparatus for the conditioning. According to the invention the plastics material pre-forms are present in the tempering space for a period of at least 5 minutes. It is thus also proposed with respect to the method that the plastics material pre-forms should remain in the tempering space for a specified time (a minimum of 5 minutes) in order to leave it at a substantially constant equal temperature in this way. 
     It is desirable for the tempering space to have air flow through it. In this case the through-flow can take place in the conveying direction of the plastics material containers, in a direction opposed thereto, or even in other directions. It is advantageous for the plastics material pre-forms to be conveyed non-sorted at least locally through the tempering space and, in a particularly exemplary manner, on at least one conveyor belt. 
     In the case of a further advantageous embodiment the apparatus is acted upon with waste air from a heating device which is situated upstream of the shaping device and/or with waste air from the shaping device itself. 
     It is advantageous for a position of the plastics material pre-forms to be altered at least for a time with respect to an air flow for tempering purposes. This can be carried out for example by the plastics material pre-forms passing or dropping from a first conveying device onto a second conveying device or even by being moved in a direction opposed to their conveying device in a purposeful manner by turning devices and/or shaking devices inside the apparatus for the conditioning. 
     It is advantageous for the plastics material pre-forms to be conveyed in a variable geometrical position with respect to one another. In the case of a further advantageous embodiment the plastics material pre-forms are heated once more after leaving the apparatus for the conditioning. In the case of a further advantageous embodiment the plastics material pre-forms are heated once more before they arrive in the apparatus for the conditioning. It would also be possible, however, for the plastics material pre-forms to arrive in the apparatus for the conditioning immediately after they have been finished or produced. 
    
    
     
       DESCRIPTION OF THE DRAWING 
       Further advantageous embodiments are evident from a drawing in several figures, of which: 
         FIG. 1  is an illustration in the manner of a block diagram of a plant according to the invention for the treatment of containers; 
         FIG. 2  is a diagrammatic illustration of an apparatus according to the invention for the conditioning of plastics material pre-forms; 
         FIG. 3  is a diagrammatic illustration of a guide system for plastics material pre-forms; 
         FIG. 4  shows a possible distribution for the plastics material pre-forms inside the tempering space; 
         FIG. 5  is a further illustration for conveying the plastics material pre-forms through the tempering space; 
         FIGS. 6 a -6 c    are three diagrams to illustrate a temperature pattern of the plastics material pre-forms, and 
         FIGS. 7 a -7 b    are two illustrations to explain the air tempering for an apparatus according to the invention. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  is an illustration in the manner of a block diagram of a plant  40  for the treatment of plastics material containers. In this case an injection molding machine  42  is provided here which produces the plastics material pre-forms and delivers them first of all to a first cooling device  44 . If the plastics material pre-forms produced are not to be immediately further processed, they can be delivered to a magazine or store  48  of plastics material pre-forms by way of a second cooling device  46 . If the plastics material pre-forms are to be formed into plastics material containers immediately after that, they are first transferred to an apparatus for the conditioning  1  according to the invention or are conveyed through this apparatus. 
     Inside the apparatus  1  the plastics material pre-forms are acted upon with heated air which is supplied in the direction of the arrow P 1  and is removed in the direction of the arrow P 2 . It would also be possible, however, for the flow to be guided in the opposite direction, so that the air flows from the interior of the apparatus  1  in a direction opposed to the conveying direction P of the plastics material pre-forms. The apparatus  1  is adjoined by a tempered separating device  56  in which the plastics material pre-forms are separated on the one hand and are brought to an equal temperature level on the other hand. After that, the heated plastics material pre-forms are supplied to a shaping device  20  such as for example a stretch blow molding machine. In this case this stretch blow molding machine has in turn a heating device  58  in which the plastics material pre-forms are brought to a temperature which is suitable for the shaping procedure. 
     Alternatively, it would also be possible for the plastics material pre-forms to be supplied from a magazine or a plastics material store  52 , optionally by way of a pre-heating unit  54 , to the apparatus  1  according to the invention. The first cooling device  44 , i.e. the after-cooling station, is usually a component part of the injection molding machine  42  and cools the plastics material pre-forms to a temperature of approximately 70°, so that they are not damaged or deformed during the following conveying. 
     In the apparatus  1  according to the invention or in the tempering space the plastics material pre-forms advantageously lie non-sorted in the manner of bulk material on a conveyor belt or a similar conveying system and they are cooled or heated with a defined air flow (which can be directed optionally in or contrary to the conveying movement of the plastics material pre-forms). On account of the long duration of the dwell period the temperatures of the plastics material pre-forms approach a controlled circulation temperature in an asymptotic manner. In this case the system can comprise for example one or more thermally insulated conveyor belts which are acted upon in a regulated manner with heated air. Reference number T relates to a conveying direction of the plastic preforms  10 . 
     The reference number  36  relates to a line by which waste air can be conveyed out of the shaping device  20  to the apparatus  1 , and the reference number  38  relates to a line by which waste air can be conveyed out of the heating device  58  to the apparatus  1 . In this case it would also be possible for the lines  36  and  38  to open into a common collecting line and for a mixing device to be provided which by the respective mixing ratios regulates the temperature of the air flowing into the apparatus  1 . 
       FIG. 2  shows a possible embodiment of a conditioning apparatus  1  according to the invention. In this case the plastics material pre-forms are conveyed along a spiral path from a supply device  4  through a tempering space  2  and are removed from the tempering space  2  again by way of a removal device  6 . The reference number  12  relates to a guide rail along which the plastics material pre-forms slide through the tempering space  2  also under the action of gravity. In this case it is also possible for the conveying path inside the tempering space  2  to be designed in the form of an accumulation path, so that the tempering space  2  or the apparatus  1  can also act as a buffer. 
     In addition, it would also be possible for the tempering path discussed above to be formed from a plurality of conveying units which are arranged one above the other or adjacent to one another and which are connected to one another. In this case it is desirable for all the portions or only individual portions to be fed by a tempering unit. The apparatus shown in  FIG. 2  can also, however, act as an ascending conveyor. 
     In this case it is advantageous for the system to be designed to be as compact as possible and, in addition, also for the outer faces  3  to be insulated in order to keep the energy requirement to a minimum. It is desirable for the air tempered in a controlled manner to be conveyed in a circuit in the interior of the tempering space  2  or to be fed back again into the flow line by way of a circulating air heat exchanger described in detail below or a circulating air mixer, in order to lose as little energy as possible to the environment. 
     In this way, it would be possible for the tempering space  2  to be fed with waste heat from the furnace, a microwave heating means, a compressor, a compression cooler or the like. The reference number  16  designates roughly diagrammatically a sensor device which detects a temperature inside the tempering space  2 , or expressed in more precise terms, a temperature of the air in the tempering space  2 . It would also be possible for a plurality of sensor devices  16  of this type to be provided. In addition, a control device or regulating device can also be provided (not shown) which carries out a control or regulation of the temperature inside the tempering space  2  in reaction to measured temperatures. 
       FIG. 3  is an illustration to explain the conveying of the pre-forms. In the case of this embodiment the plastics material pre-forms in a guide rail  18  are gripped below their support ring  10   b  and are conveyed in this way. In addition, it would also be possible for the region  19  to be acted upon with cooler air so as to treat a thread  10   a  of the plastics material pre-forms still more gently in this way. 
       FIG. 4  shows two possible designs of the conveying or the structured arrangement of the plastics material pre-forms  10  inside the tempering space. In this case the arrows w relate to the supply of heated air. In the case of the left-hand design the plastics material pre-forms are situated in alignment with one another and in the case of the right-hand design they are offset one behind the other. 
       FIG. 5  shows a further arrangement of an apparatus according to the invention. In this case the plastics material pre-forms are conveyed from one path  32  for example to three paths  34   a ,  34   b  and  34   c  or more and are conveyed on these three paths through the tempering space  2 . 
     It is possible for the plastics material pre-forms to be supplied separately, but a conventional supply can also be used which is enclosed and is kept at the nominal temperature of the plastics material pre-forms. In the case of this design the plastics material pre-form should no longer be heated or cooled, but should only keep its temperature. 
     The shaping device  20  shown in  FIG. 1  can, as mentioned above, manage with a smaller profiling furnace as compared with the prior art, since significantly less energy is used for heating the plastics material pre-forms. 
     The second cooling device  46  ( FIG. 1 ) can also be used, in the event of a prolonged disruption at the blow molding machine or in the event that other plastics material pre-forms are produced on the injection molding machine  42  than are required on the shaping device  20 , in order to cool the plastics material pre-forms to a sufficiently low temperature for the plastics material pre-forms to be capable of being transferred into the store  48  without problems. In the store  48  the plastics material pre-forms can be stored in crates or the like, but so-called pre-form silos would also be possible. 
     The conveying device  54  is used in particular in the event of a failure of the injection molding machine  42  or in the event that other plastics material pre-forms are processed on the shaping device than are produced just on the injection molding machine  42 . In this case the plastics material pre-forms can, if necessary, be taken from a store  52  of plastics material pre-forms and can be pre-heated. In addition, it would also be possible for the pre-heating unit  54  to be incorporated in the apparatus  1  according to the invention. It is also possible for cold plastics material pre-forms from octabins or the like to be supplied, if necessary, from the store  52 . 
     In the event of a disruption the conveying device  12  remains in the tempering space  2 . On account of the fact that the plastics material pre-forms are brought to the ambient temperature in an asymptotic manner in the tempering space  2 , they cannot overheat but at most adopt the temperature of the surrounding air which is tempered in a controlled manner. 
     In addition, it is possible for the plastics material pre-forms in the tempering space  2  and/or in the supply to be arranged in a structured manner as shown in  FIG. 4  on a conveying device. In this case the distance s 1  of the plastics material pre-forms as shown in  FIG. 4  should advantageously be kept as small as possible and the distance s 2  should be set for example to lengths in the range of between 30 and 60 mm, or between 40 and 50 mm, in a particularly exemplary manner in the range of 44 mm. The deviation from the nominal temperature and the duration of the dwell period and thus the overall energy consumption can be reduced in this way. In addition, it would be possible, in the case of a structured arrangement, for the openings to be separated off, as shown in  FIG. 3 , in order to prevent unnecessary heat input. 
     It would also be possible for a tempering in the tempering space  2  to be used only in order to equalize the starting conditions of normal plastics material pre-forms of for example 0 degrees from outside in winter and 40 degrees adjacent to the furnace and to bring them to a constant starting temperature of 45 degrees. 
       FIGS. 6 a  to 6 c    show possible temperature patterns of the plastics material pre-forms with a wall thickness of 4 mm over the duration of the heating of the outer wall.  FIG. 6 a    shows an example of forced convection. It is evident that a temperature difference of 70 K (curve K 1 ) or an increase in temperature of from 20° C. to 90° C. is substantially achieved in a time frame of approximately 10 minutes. If, as indicated by the curve K 2 , a temperature difference of 47 K is to be achieved, this is also possible in a time period of approximately 10 minutes.  FIG. 6 b    shows the same procedure in the case of free convection. It is evident that in this case substantially longer periods of time are necessary in order to achieve a heating to the ambient temperature of 45° C. As is evident from the curve K, a temperature in the range of 45° C. is achieved only after approximately 3 h. 
       FIG. 6 c    shows three possible temperature patterns, in which it is evident that the temperatures of the plastics material pre-forms have converged with one another very closely essentially independently of the starting temperature at a specified time T 1 , in which case the fluctuations still existing can also be accepted for the processes to be pursued. 
     It would also be possible for the apparatus according to the invention to be used only in order to improve the overall energy balance of a stretch blow molding plant. In this case the injection molding plant can be omitted completely and instead the operation is carried out with the “pre-form store supply”, as described above, with plastics material pre-forms injection molded at another location at room temperature. Although no residual heat is used from the preceding process in this case, the heating of the tempering path is possible with substantially less outlay and also with less energy input, since more time is available for the introduction of the energy. The convective heat input by way of hot air and the thermal conduction is considerably better in terms of efficiency than the introduction of energy by means of infrared radiation on a short path. In this way, the overall efficiency of the plant is improved and the less efficient infrared heating path can be shortened with respect to a standard stretch blow molding plant. 
     The deviation of the nominal temperature is lowered to a minimum after tempering in the pre-heating path by tempering and insulation of the separating means and supply rail to the blow molding device. The temperature distribution in and between the plastics material pre-forms is subsequently homogenized by a structured arrangement of the plastics material pre-forms in the supply to the blow molding device. 
     In order to reduce the deviation of the nominal temperature further it is expedient to mix the plastics material pre-forms during the conveying through the tempering path in a permanent manner or at diverse time intervals in order to change the position of the individual plastics material pre-forms in the hot air flow. This can take place for example by way of a stirring unit or even by way of a shaking apparatus or even a shifting during the conveying between a plurality of conveyor belts. 
       FIGS. 7 a  and 7 b    are two illustrations to explain the heat recovery. In this case it is possible for example for outside air AU to be supplied to a heat exchanger  28 , this heat exchanger  28  also being integrated in the heat circuit with the apparatus  1  according to the invention. The reference number  22  designates a fan unit which, in the same way as a further fan unit  24  supplies heated air to the apparatus  1  or the tempering space  2  and also removes it again. In addition, a pre-heating means  26  for pre-heating the air supplied to the apparatus  1  can be provided. This pre-heating means  26  can also be a water/air/heat exchanger and the fan units  22 ,  24  can also be axial fans. On account of a recovery of the heat content of the waste air AB it is possible to achieve a considerable reduction of the energy consumption. In this case this waste air AB is supplied to the heat exchanger  28  mentioned above. The reference ZU relates to the supply air. 
     In this way, in the case of the variant shown in  FIG. 7 a   , a recovery of heat takes place by way of the circulating air heat exchanger  28 . 
       FIG. 7 b    shows a further variant, in which the recovery of heat takes place by way of an admixture of circulating air. For this purpose a mixing unit  50  is provided in place of the heat exchanger  28 . In the mixing chamber of this mixing unit a certain amount of discharge air FO is admixed with the outside air in order to reduce the energy consumption of the after-heating means as a result, in order to save energy in this way. The reference U relates in this case to circulating air and the reference M relates to mixed air. 
     Whereas the pre-heating output is 69 or 67 KW during the procedure shown in  FIGS. 7 a  and 7 b   , without this recovery of heat 102 kW of pre-heating output are required. 
     LIST OF REFERENCES 
     
         
           1  apparatus 
           2  tempering space 
           3  outer face 
           4  supply device 
           6  removal device 
           10  plastics material pre-form 
           10   a  thread 
           10   b  support ring 
           12  conveying device 
           16  sensor device 
           18  guide rail 
           19  region 
           20  shaping device 
           22 ,  24  fan units 
           26  pre-heating means 
           28  heat exchanger 
           32  path 
           34   a ,  34   b ,  34   c  paths 
           36  line to the waste air supply from the shaping device 
           38  line to the waste air supply from the heating device 
           40  plant 
           42  injection molding machine 
           44  first cooling device 
           46  second cooling device 
           48  store of plastics material pre-forms 
           50  mixing unit 
           52  store of plastics material pre-forms 
           54  pre-heating unit 
           56  separating device 
           58  heating device 
         K, K 1 , K 2  curves 
         T 1  temperature 
         AB waste air 
         ZU supply air 
         FO discharge air 
         U circulating air 
         M mixed air 
         T conveying direction 
         P 1 , P 2  arrows 
         w air flow 
         s 1 , s 2  distance