EP2507034A1

EP2507034A1 - Furnace for conditioning preforms

Info

Publication number: EP2507034A1
Application number: EP10776559A
Authority: EP
Inventors: Frank Winzinger; Christian Holzer; Wolfgang Schönberger; Konrad Senn; Andreas Wutz
Original assignee: Krones AG
Current assignee: Krones AG
Priority date: 2009-12-04
Filing date: 2010-10-20
Publication date: 2012-10-10
Also published as: DE102009047541A1; US20130011807A1; CN102725123A; CN102725123B; WO2011066886A1; IN2012DN04916A

Abstract

The invention relates to a rotary-type furnace for conditioning preforms, in particular for the stretch blow moulding of plastic receptacles, said furnace comprising a heating wheel on which a plurality of heating modules, each for heating one preform, are arranged. Reproducible heating of said preforms by the regulation of the individual heating modules is guaranteed by the provision of a temperature measuring device for measuring at least one temperature of the preform and/or of the heating chamber, on the heating modules, and by the fact that the furnace additionally comprises a control device for actuating the heating modules on the basis of the temperatures that have been measured.

Description

Furnace for conditioning preforms

The invention relates to a rotary type kiln for conditioning preforms according to the preamble of claim 1, a method for calibrating heating modules of the furnace according to the invention and a method for conditioning preforms in the furnace according to the invention.

Containers to be produced in the blow-molding or stretch blow molding process are formed from so-called preforms or preforms, which must be heated to a desired process temperature before the actual blowing process. In order to transform the rotationally symmetrical preforms, which generally have standardized wall thicknesses, when blowing into containers having a specific shape and wall thickness, individual wall areas of the preform are to be heated in a metered manner, preferably with infrared radiation. For this purpose, usually a continuous stream of preforms is passed through a furnace with appropriately adapted irradiation sections. A problem of such ovens, however, is to introduce as much of the radiated heat output as possible in the preforms.

As an alternative to this, the published patent application DE 10 2006 015853 A1 proposes to heat preforms into individual irradiation chambers surrounding the preforms in each case circumferentially, wherein the individual chambers are arranged in the form of a carousel. In this case, each preform is heated both by the inner wall of the chamber designed as a ceramic infrared radiator and by a rod-shaped infrared radiator introduced into the preform.

In the furnace of DE 10 2006 015 853 A1, however, it may happen that individual preforms are heated to a different degree due to a tolerance of the heating chambers or heating elements to one another and / or a tolerance in the positioning of the preforms in the heating chambers. In addition, it would be desirable to adapt the heating chambers and / or the heating elements for the irradiation of differently sized preforms and / or to condition certain areas of the preforms specifically for a subsequent blowing process.

There is thus a need for a single-chamber furnace which is suitable for preforms of different sizes and in which the preforms are heated as uniformly as possible in all the heating chambers of the furnace. This object is achieved with a furnace comprising the features defined in the characterizing part of claim 1. Characterized in that the heating modules comprise a temperature measuring device for measuring at least one temperature of the preform and / or the heating chamber, a heating energy which is likely to be required can be estimated more accurately. The fact that the furnace further comprises a control device for controlling the heating modules, in particular the radiant heater and the holding and lifting devices, based on the measured temperature, the temperature measured values can be processed in the control device and set the heating power and / or heating time of the individual heating modules targeted to heat the preforms as much as possible to the desired extent and in all heating modules.

Preferably, the temperature measuring means comprises a central upstream temperature sensor for measuring a preform start temperature and / or remote temperature sensors provided at the heating chambers for measuring a temperature of the heating chamber during heating. By measuring the starting temperature of the preform, in particular a desired value of the heating power can be determined in order to ensure a desired heating of the preform in the heating chamber. By decentralized temperature sensors on the heating chambers, the temperature rise in the heating chamber can be monitored and readjusted if necessary.

The control device is preferably set up in order to set a heating power of the heating module, a heating duration and / or a residence time of the preform in the heating chamber on the basis of the measured temperature. As a result, an amount of heat actually emitted, in particular a heat energy actually emitted, can be adapted to a calculated desired value of the heat quantity or the heating energy.

In a particularly favorable embodiment, the heating chamber comprises a bottom which can be adjusted in an axial direction with respect to the main axis of the preform. Thereby, the length of the heating chamber can be adapted to the length of the preform and the same heating chamber can be used for preforms of different lengths. A change between different sized heating chambers is thus unnecessary.

Preferably, the adjustable bottom is actively heated and / or infrared radiation reflective formed. As a result, the preform can be effectively irradiated, in particular in a bottom region of the preform.

The heating chamber preferably comprises a plurality of radiant heaters arranged one behind the other in an axial axial direction with respect to the main axis of the preform, which are separated from one another can be operated to adapt an active radiator surface formed by the operated radiant heaters to a region of the preform to be irradiated. As a result, the heat radiation emitted can be adapted particularly precisely to the area of the preform to be irradiated. In addition, the radiant heaters can be switched off in a targeted manner not to be irradiated area of the heating chamber, in particular in a region below the adjustable floor. As a result, the preform can be heated in a targeted and energy-efficient manner, and it can be avoided that the heating chamber inadmissibly heats up, in particular below the adjustable bottom.

In a particularly advantageous embodiment, the heating modules each further comprise a heating element for irradiating the preform with infrared radiation, and the holding and lifting device is further adapted for raising and lowering the heating element to insert the heating element in the preform or withdraw from this. As a result, the preform can be irradiated or heated particularly effectively from its inner side and, depending on the requirements, in a particularly targeted or particularly uniform manner.

Preferably, a maximum depth to which the heating element can be inserted into the preform is adjustable. As a result, it can be avoided, on the one hand, that the heating rod collides with the bottom of the preform and, on the other hand, that a bottom region of the preform is only insufficiently irradiated or heated by the heating element.

Preferably, a plurality of heat radiators arranged one after the other in an axial axial direction with respect to the main axis of the preform are formed on the heating rod and can be operated separately to adapt an active radiator surface formed by the operated radiant heaters to a region of the preform to be heated. On the one hand, it can thereby be avoided that areas of the heating module are irradiated outside the preform and possibly overheated; on the other hand, the radiator surface can be adapted in a particularly favorable manner to irradiation of the tear-off edge of the preform in the neck region of the container to be blown.

In a preferred embodiment, a support plate for a formed on the preform support ring is provided on the heating chamber, wherein the support plate is connected to the heating chamber via a plug-in coupling and / or a magnetic coupling quickly changeable. As a result, the heating chamber is suitable for the irradiation of preforms with different diameters of the support ring or of the portion of the preform to be irradiated. With such a coupling, the oven can be particularly quickly adapted for conditioning differently sized preforms. In an advantageous embodiment, support plates can be easily placed on the heating chamber without additional connectors. For this purpose, a stop in the radial direction can be sufficient.

In a particularly favorable embodiment, an axial transformer or a slip ring for supplying power to the heating modules is provided on the heating wheel, and the control device is arranged co-rotating on the heating wheel. As a result, the number of lines required for the power supply or control of the heating modules can be reduced or the routing can be simplified.

The object underlying the invention is further achieved by a method for calibrating the heating modules of the furnace according to the invention, wherein the method comprises the steps defined in claim 12. By comparing the effectiveness of the heating modules to be calibrated with a reference model of the heating modules, an individual correction value can be determined for each heating module in order to adapt the electrical energy to be introduced into the individual heating modules to a common target value of the temperature increase and / or heating duration.

The underlying object is further achieved with a method for conditioning preforms, in particular for the stretch blow molding of plastic containers, in the oven according to the invention, the method comprising the steps defined in claim 13. Because the heating modules are individually controlled or regulated on the basis of a measured starting temperature of the preforms, the preforms can be heated uniformly and in all heating modules uniformly.

The underlying object is also achieved by a method for conditioning preforms, in particular for the stretch blow molding of plastic containers, in the oven according to the invention, the method comprising the steps defined in claim 14. By controlling the heating modules on the basis of a temperature value measured in the heating chamber during the heating, the preforms can be heated uniformly and in all heating modules.

Preferably, the heating modules, in particular their heating energy supply and the dwell time of the preforms in the heating chambers, are furthermore controlled or regulated on the basis of the individual correction values determined in the calibration method according to the invention. As a result, the individual preforms in the heating chambers can be heated in a particularly uniform and uniform manner, since both the heating time and the heating time in the heating chamber are increased. In each case, the amount of heat available in each case can be adjusted uniformly and substantially uniformly for all heating chambers.

In an alternative embodiment, the preforms are not suspended but received with the mouth region in the vertical direction downwardly standing in the heating chamber.

The furnace may be designed to heat preforms only with certain heating chambers. This may be necessary if you want to operate the oven with a lower output of preforms. The heating chambers, which are not equipped, remain empty. For example, it is possible to equip only every second heating chamber with a preform. Heating chambers that are not equipped, are preferably not heated. The distance between the preforms can be compensated after heating for blowing on individual blow molding stations.

In a preferred embodiment, a value is measured from a container made from the preforms and reported back to the heating chamber in which the preform in question has been heated. The measured value is preferably a wall thickness of the finished container.

In a preferred embodiment, a temperature is detected at one or more radial or axial locations of the preform and a correction value is reported back to the respective heating chamber. Thus, a uniform as possible heating behavior per heating chamber should be achieved for each preform.

Preferred embodiments of the invention will be explained with reference to the drawings. Show it:

Fig. 1 is a schematic plan view of a furnace according to the invention of

Rotary type;

2a and 2b are schematic longitudinal sections through variants of the heating chambers according to the invention;

3 shows a schematic longitudinal section through a variant of the heating chambers according to the invention with adjustable bottom.

4 shows a schematic partial view of the heating modules according to the invention with a height-adjustable heating element; 5a and 5b are schematic longitudinal sections through variants of the heating chambers according to the invention with quickly exchangeable support plates.

6 shows schematic longitudinal sections through rapidly exchangeable heating chambers; and

7a to 7c show a schematic representation of a rapidly exchangeable heating element and the use of heating elements of different lengths in the irradiation of preforms of different sizes.

1, the oven 1 according to the invention is designed as a rotary machine and comprises a rotatably mounted heating wheel 2 on which circumferentially uniformly distributed a plurality of heating modules 3, each with a heating chamber 4 for heating a preform 5 are arranged. The preform rings 5 can be taken over by holding and lifting devices 6 (not shown in FIG. 1) from a conventional inlet star wheel 7 and transferred into the heating chambers 4, preferably lowered. The heated preforms 5 are correspondingly transferred to a conventional outlet starwheel 8 for further processing of the preform 5 in a blowing process. It would also be possible to move the heating chambers 4 through the holding and lifting devices 6.

The holding and lifting devices 6 may comprise, for example, pivotable outer or inner gripper for holding the preforms 5 and / or drives for carrying out a rotational movement between the preforms 5 and the heating modules 3. Also on the holding and lifting devices 6 radiation shields and / or cooling fins or cooling channels may be provided, which are not shown for the sake of clarity in the following.

Furthermore, a temperature measuring device 9 is provided, of which only temperature sensors 10a to 10c are simplified in FIG. 1, which are arranged on the inlet starwheel 7, the outlet starwheel 8 or on the heating wheel 2 on each of the heating modules 3. For the sake of clarity, only one of the sensors 10c is shown. The inlet-side temperature sensor 10 a serves to determine a starting temperature of the preform rings 5 before feeding the preform rings 5 into the heating modules 3. Accordingly, the outlet side temperature sensor 10b on the outlet starwheel 8 is configured to measure an end temperature of the preform rings 5 after heating in the heating modules 3. The temperature measuring device 9 thus comprises central or common sensors 10a, 10b, on which successively all the preform rings 5 pass. In contrast, the temperature sensors 10 c are designed to be decentralized, so that the temperature measuring device 9 is designed for the separate determination or monitoring of the temperature in or on each of the heating chambers 4. The temperature measuring device 9 may have a However, any combination of the temperature sensors 10a to 10c also include only the sensor 10a, 10b or the sensors 10c.

1 also shows a central slip ring 11 for the power supply of the heating modules 3 and at least one control unit 12, which is set up for processing measuring signals of the temperature measuring device 9 and for controlling the heating modules 3, in particular for controlling the heating power and the heating duration of the individual heating modules 3 and The residence time of the preforms in the heating chambers 4. Since the control units 12 rotate with the heating wheel 2, they are particularly easy to connect to the temperature sensors 10 c and the heating modules 3. Measuring signals of the stationary sensors 10a, 10b could, for example, be transmitted to the control unit 12 by radio or via the slip ring 11. As an alternative to the slip ring 11, an axial transformer is conceivable.

2 a shows a thermally insulating heating chamber 4 according to the invention with a fixed chamber bottom 4 a and FIG. 2 b shows an alternative variant of the heating chamber 4 with a bottom element 4 b which is adjustable in height, ie along the main axis 5 'of the preform 5 to be heated. 2a and 2b also differ in that in the heating chamber 4 of Fig. 2a, a comparatively long preform 5 is introduced, in the heating chamber 4 of FIG. 2b, however, a comparatively short preform 5, at the length of which the position of the bottom 4b is adjusted. Shown further are a central, height-adjustable heating element 13 as an optional component of the heating module 3, the depth of immersion in the heating chamber 4 is adapted to the length of the respective preform 5, and annular, stacked heating elements or radiator 14 on the inner wall of the heating chamber 4. Der Preform 5 can either be held by the holding and lifting device 6 (not shown) above the heating chamber 4, as shown in FIG. 2a, or, as shown in FIG. 2b, with a support ring 5a formed on the preform 5 on a support plate 4c of the heating chamber 4 rest.

The heating elements 14 are preferably individually controllable, so that in particular only those heating elements 14 can be actively operated during heating of the preform 5, which are substantially opposite a wall portion 5b of the preform 5 to be heated. The heating elements 14 can also be controlled with regulated or throttled power. For example, it is conceivable that a heating element 14 is operated at half power. For clarity, in FIG. 2b, only those heating elements 14 are shown in white, which are substantially opposite the wall section 5b of the preform 5 to be heated and actively electrically heated in the configuration shown, whereas the non-activated or deactivated heating elements 14 'at the level of the adjustable Ground- elements 4b or underlying dark hatched are shown. This ensures that the heat output of the heating elements 14 can be used effectively to heat the preform 5 and at the same time avoid unwanted heating of areas of the heating chamber 4 not to be irradiated, such as the lateral or lower regions of the adjustable bottom 4b becomes.

The position of the height-adjustable bottom 4b can be adapted to preforms 5 of different lengths, for example by means of an adjustment mechanism indicated in FIG. 2b by a block arrow. The irradiation-side surface 4d of the adjustable bottom 4b is preferably designed to reflect infrared radiation. Likewise, in the displaceable bottom 4b, a region 4e may be formed, in which the irradiation-side surface 4d is adapted to the shape of the preform 5, for example in the form of a bulge. Thereby, the bottom portion of the preform 5 can be irradiated particularly effectively and uniformly.

The position of the height-adjustable bottom 4b could be set automatically, for example manually or via the control device 12. Accordingly, the position of the heating element 13 could be adjusted manually or automatically via the holding and lifting device 6. With the height-adjustable heating element 13 and the height-adjustable bottom element 4b, preforms 5 of different sizes can be heated in the same heating chamber 4, so that an exchange of the heating chambers 4 is dispensable when changing between preforms 5 of different sizes. This reduces set-up times of the furnace 1 and makes it unnecessary to stock a large number of different heating chambers 4 or heating rods 3.

FIG. 3 shows a variant of the heating chamber 4 with a height-adjustable bottom element 4b, which comprises at least one electrically active heatable heating radiator 15. The further features of the heating chamber 4 of FIG. 3 essentially correspond to the previously described variants of the heating chamber 4, so that corresponding features will not be described again. However, in addition to the support plate 4c, or formed directly on this, infrared radiation-reflecting shields 16 and 17 are provided for shielding a mouth region 5c of the preform 5 against that of the heating elements 14, 15 and the heating element 13 in a region of the preform 5 delivered thermal radiation. This optical shield, which could additionally also be cooled by a stream of air or by a liquid, prevents the orifice area 5c from undesirably heating up in order to ensure sufficient stability of the mouth area 5c during the heating in the heating chamber 4 and the subsequent blowing process. With the actively heated Heating elements 15 of the bottom 4b improved heating of the preform 5 in the bottom portion 5d of the preform 5 is achieved.

The adjustment of the displaceable bottom element 4b and / or the height-adjustable heating element 13 could be carried out so that all heating modules 3 are brought in this regard during a revolution of the heating wheel 2 from an actual position to a desired position. The bottom elements 4b and / or the heating rods 13 could then be fixed via a (not shown) clamping device until a new height adjustment is required.

4, a height-adjustable heating element 13 is shown schematically. In particular, a plurality, in the axial direction, ie along the main axis 5 ', one above the other arranged radiant heaters or heating elements 18 are provided on the heating element 13, which are preferably individually controlled. 4, the heating elements 18 of the heating element 13 form an axial inner heating region 19 substantially corresponding to a first common radiating surface of the heating elements 18 for irradiating the preform 5 from its inside, and the heating elements 14 of the heating chamber 4 an axial outer heating region 20, substantially corresponding to a second common radiator surface of the heating elements 14 for irradiating the preform 5 from its outer side. In this case, the axial inner heating region 19 preferably extends further in the direction of the mouth region 5c of the preform 5 than the axial outer heating region 20. As a result, the inner side 5e of the preform 5, in particular in an area adjacent to the supporting ring 5a, can be selectively irradiated to the so-called trailing edge for the subsequent blowing of the vessel targeted train. In this case, the location of the preform 5 at which the preform 5 is stretched under the support ring 5a when the vessel is blown is designated as the tear-off edge. In order to optimally form the neck region of the vessel, in particular in order to avoid an oblique neck, the axial or vertical position of the tear-off edge can be adapted flexibly with the aid of the heating rod 13.

This can be achieved, for example, by displacing the position of the radiant heaters 18 in the region of the trailing edge to be formed, or by heating only individual radiant heaters 18 actively. By such internal heating of the preform 5 with the heating element 13, the material of the preform 5 which is available for drawing in the blow molding process can be utilized in the best possible way. This ensures, in particular, that the tear-off edge is formed at a suitable location and that as much material of the preform 5 passes from the area under the support ring 5a into the shoulder of the vessel to be formed and ensures sufficient stability there. FIGS. 5a and 5b show variants of the heating chamber 4, in which the support plate 4c for the support ring 5a of the preform 5 is designed in the form of a rapidly exchangeable support plate 21. In the example, the support plates 21 shown are connected via a magnetic coupling 22 to the heating chamber 4. As FIGS. 5 a and 5 b also show, the heating module 3 with the quickly exchangeable support plate 21 can be adapted to preforms 5 with different outer diameters in a simple and time-saving manner. Such quickly exchangeable support plates 21 could be combined with the described variants of the heating chambers 4 arbitrarily.

Preferably, the heating element 3 is variably adjustable in the vertical direction with respect to the immersion depth in order to more or less strongly heat the region of the neck of the bottle to be formed. Likewise, the immersion depth of the preform can be adjusted in the heating chamber to more or less strongly heat the area of the bottle neck.

Fig. 6 shows a variant of the heating module 3, in which the heating chamber 4 itself is designed as a quick-change component. Fig. 6 shows, for example, at the position I, a comparatively large heating chamber 4, which is connected via a coupling 25, such as a plug-in coupling, with the heating 2 fast changeable. This heating chamber 4 could for example be exchanged for a provided with an identical coupling 25 heating chamber 4 with smaller dimensions, as indicated by the positions II to IV. This procedure is particularly advantageous if the size of the preforms 5 to be exchanged differs particularly strongly. In the couplings 25 suitable electrical connections or other required for the operation of the heating chamber 4 compounds could be integrated.

Fig. 7a shows a heating element 13, which can be connected via a quick-change coupling 26, such as a plug-in coupling with the holding and lifting device 6. As indicated in FIGS. 7b and 7c, it is thus possible to change between heating elements 13 of different lengths in a simple manner and to adapt the heating modules 3 to preforms 5 of different lengths. For example, it can be avoided that a heater rod 13 that is too long for a preform 5 collides with the preform 5 when the heating rod 13 is lowered, or that too short a heating rod 13 can not be lowered far enough into a preform 5 to be heated.

With the described quickly changeable variants of the support plate 21, the heating chamber 4 and the heating element 13, which can be combined as desired, the furnace 1 can be particularly easy and fast when changing between preforms 5 different dimensions be converted. In this case, in addition to magnetic couplings and plug-in couplings, other quick-release closures are also conceivable.

The embodiments or variants described above can be combined in any advantageous manner.

A method for calibrating the furnace 1 according to the invention, in particular the individual heating modules 3 or the heating chambers 4, is described below:

Due to the manufacturing process, the heating chambers 4 and the heating elements 13 are subject to a certain tolerance. This applies not only to the shape and dimensional accuracy of the heating chambers 4 and the heating elements 13, but also to the composition of the materials, which may contain, for example, ceramic material mixtures, such as functional ceramics, as components of the radiators 14, 15, 18 which are particularly relevant for the energy input , As well as the structure of the heating chambers 4 and the heating elements 13, in particular with respect to the heat transfer between individual functional components and / or material layers. For the subsequent blowing process, however, it is desirable for the preforms 5 in the furnace 1 according to the invention, in spite of such tolerances, to be heated as reproducibly as possible and identically to the desired process temperature in all heating modules 3.

Therefore, identical reference models 4 'and 13' are provided for the types of the heating chambers 4 and the heating rods used in the furnace 1 to provide corresponding reference coefficients of effectiveness 31 ', 32' as comparison standard for the individual heating chambers 4 used in the furnace 1 or heating rods 13 to be determined by comparative measurement.

Preferably, a reference coefficient of effectiveness 33 'for the heating module 3' consisting of the reference models 4 'and 13' is determined as a comparison value, which correlates the electrical power used and / or the duration of the electrical power supply to the heating module 3 ' caused heating of the heating chamber 4 'and / or one in the heating chamber 4' arranged preform 5 produces. The reference coefficient of effectiveness 33 'is preferably provided for a multiplicity of possible settings of the heating module 3', for example for different positions of the adjustable heating chamber bottom 4b 'or the heating elements 13' and / or a different number or arrangement of actively operated heating elements 14 ', 15 'and 18' of the reference model 3 '.

For this purpose, for example, a specific electrical energy to be fed in may be specified and the associated temperature increase measured, or vice versa. Preferably, values of the reference coefficient of effect 33 'determined in this way are determined using the associated parameters, such as the position of the chamber bottom 4b 'in the form of a reference value table 34' in the control device 12 is stored. Optionally, the reference effect coefficients 31 ', 32' can also be determined in separate (not further described) measuring devices and stored in corresponding reference value tables 34 '. Different variants for calculating comparison values are conceivable here.

In advance of the conditioning of the preforms 5, an associated individual coefficient of effectiveness 33 or separate individual coefficients of effect 31, 32 of the individual module components 4, 13 is determined for each heating module 3 of the furnace 1. The procedure corresponds in each case to the associated reference model 3 ', so that comparable individual effect coefficients 31, 32, 33 or value tables 34 can be provided for each heating module 3 of the furnace 1.

In the conditioning of the preforms 5, the effect coefficients 31, 32 and / or 33 or the value tables 34 of individual heating modules 3 are each separately calculated from the reference coefficients 31 ', 32' and / or 33 'or the values of the reference tables 34'. to obtain an individual correction value 35 for each of the heating modules 3. This correction value 35 can then be used to compensate for a different heating efficiency of the individual heating modules 3 or a different thermal efficiency in order to condition the preforms 5 in all heating modules 3 substantially identically. In this case, different calculation variants are conceivable, such as adaptive algorithms and the combination of different value tables 34 or 34 '.

The furnace 1 according to the invention can be used, for example, as follows:

A continuous stream of preforms 5 to be heated is guided past the inlet-side starwheel 7 past the input-side temperature sensor 10a, wherein the starting temperature of the preforms 5 to be heated is determined in each case and evaluated by the control and regulation unit 12. The preforms 5 are then each supplied to a heating module 3 of the rotating heating wheel 2 and lowered with the lifting device 6 in the heating chambers 4 of the heating modules 3.

Preferably, taking into account the individual correction value 35, a desired electric power and a desired heating duration are set by the control unit 12 for each heating module 3 and the heating modules 3 are heated accordingly. The heating of the preforms 5 is checked by the decentralized temperature sensors 10c and can, depending on the end of the heating on the basis of the thus detected temperature values by the control unit 12 during be adapted to the heating. To complete the heating of the preforms 5, the power supply to the heating modules 3 is interrupted, the preforms 5 are withdrawn from the heating chambers 4 and transferred from the heating wheel 2 to the outlet star 8. There, the heated preforms 5 pass the temperature sensor 10b, with which a discharge-side process temperature of the preforms 5 is determined or checked. The respectively determined temperature is transmitted to the control unit 12 and can be used by this to adapt the energy supply in the individual heating modules 3 for subsequent heating cycles.

The calibration according to the invention and the method according to the invention are also particularly suitable when using adjustable heating chambers 4 and / or heating rods 13 to condition differently sized preforms 5 under respectively optimized conditions and thereby a reproducible and for all heating modules 3 similar temperature increase or temperature profiling of the preforms. 5 to ensure.

For example, the control device 12 could heat only each second or third heating module 3 or equip it with a preform 5, or also any desired proportion of the heating modules 3 provided on the heating wheel 2, for example, to variably adjust an output of the furnace 1 without changing the residence time of the preforms 5 on the heating wheel 2 or other parameters relevant to the conditioning.

Claims

claims

1. A rotary kiln for conditioning preforms (5), in particular for the stretch blow molding of plastic vessels, with a heating wheel (2) on which a plurality of heating modules (3) for heating each of a preform (5) are arranged, wherein the heating modules (3 ) each comprise a heating chamber (4) with at least one radiant heater (14) for irradiating the preform (5) with infrared radiation,

characterized in that

the heating modules (3) further comprise:

- A holding and lifting device (6) for holding or raising and lowering of the preform (5) and / or the heating chamber (4) to introduce the preform (5) in the heating chamber (4) or to withdraw from this ; and

- A temperature measuring device (9) for measuring at least one temperature of the preform (5) and / or the heating chamber (4);

and that the furnace (1) further comprises a control device (12) for controlling the heating modules (3), in particular the radiant heater (14) and the holding and lifting devices (6) based on the measured temperature.

2. Oven according to claim 1, characterized in that the temperature measuring device (9) comprises a central inlet-side temperature sensor (10 a) to measure a starting temperature of the preform (5), and / or decentralized temperature sensors (10 c), which at the heating chambers ( 4) are provided to measure a temperature of the heating chamber (4) during heating.

3. Furnace according to claim 1 or 2, characterized in that the control device (12) is adapted to a heating power of the heating module (3), a heating time and / or a residence time of the preform (5) in the heating chamber (4) on the basis to set the measured temperature.

4. Oven according to at least one of the preceding claims, characterized in that the heating chamber (4) comprises in a relative to the main axis (5 ') of the preform (5) axial direction adjustable bottom (4b).

5. Oven according to claim 4, characterized in that the adjustable bottom (4b) actively heated and / or infrared radiation is formed reflecting.

6. Furnace according to at least one of the preceding claims, characterized in that the heating chamber (4) comprises a plurality of, in a relative to the main axis (5 ') of the preform (5) axial direction one behind the other arranged radiant heater (14), which separated from each Other can be operated to adapt one of the operated radiant heaters (14) formed active radiator surface to a region to be irradiated (5b) of the preform (5).

7. Furnace according to at least one of the preceding claims, characterized in that the heating modules (3) further each comprise a heating rod (13) for irradiating the preform (5) with infrared radiation, and that the holding and lifting device (6) further for lifting and lowering the heating rod (13) is arranged to insert the heating element (13) in the preform (5) and pull back from this.

8. Furnace according to claim 7, characterized in that a maximum depth, up to which the heating element (13) can be introduced into the preform (5), is adjustable.

9. Oven according to claim 7 or 8, characterized in that on the heating element (13) a plurality, in a respect to the main axis (5 ') of the preform (5) axial direction successively arranged radiant heaters (18) are formed, operated separately be adapted to adapt one of the operated radiant heaters (18) formed active radiator surface to a region to be irradiated (5e) of the preform (5).

10. Oven according to at least one of the preceding claims, characterized in that on the heating chamber (4) is provided a support plate (21) for on the preform (5) formed support ring (5 a), wherein the support plate (21) with the heating chamber (4) via a plug-in coupling and / or a magnetic coupling (22) is connected quickly changeable.

11. Oven according to at least one of the preceding claims, characterized in that on the heating wheel (2) an axial transformer or a slip ring (11) for powering the heating modules (3) is provided and the control device (12) arranged on the heating wheel (2) co-rotating is.

12. A method for calibrating the heating modules (3) of the furnace according to one of claims 1 to 11, comprising the following steps:

a) providing a reference model (3 ') of the heating modules (3);

b) heating at least one heating element (14, 15, 18) of the reference model (3 ') by supplying electrical energy and measuring a temperature of the reference model (3'); c) determining a reference efficiency coefficient (31 ', 32', 33 ') for the reference model (3'), which establishes a relationship between the supplied electrical power and / or the duration of the electrical power supply and the measured temperature; d) determining individual coefficients of effectiveness (31, 32, 33) for the heating modules (3) to be calibrated in analogy to the procedure in step c); and e) calculating individual correction values (35) of the heating modules (3) for the conditioning of the preforms (5) in the heating modules (3) from the effect coefficients (31 ', 32 ", 33', 31) determined in steps c) and d) , 32, 33).

13. A method for conditioning preforms, in particular for the stretch blow molding of plastic containers, in the oven according to at least one of claims 1 to 11, comprising the following steps:

- measuring a starting temperature of the preforms (5);

- Introducing the preforms (5) in each case a heating module (3);

- Heating the preforms (5), wherein the heating modules (3), in particular their Heizenergiezufuhr and the residence time of the preforms (5) in the heating chambers (4), individually controlled or regulated based on the measured starting temperature.

14. A method for conditioning preforms, in particular for stretch blow molding of plastic containers, in the oven according to at least one of claims 1 to 11, comprising the following steps:

- Introducing the preforms (5) in each case a heating module (3);

Heating the preforms (5) and measuring at least one temperature value of the heating chamber (4) during the heating, wherein the heating modules (3), in particular their heating energy supply and the residence time of the preforms (5) in the heating chambers (4), based on the measured Temperature value individually controlled or regulated.

15. The method according to claim 13 and / or 14, characterized in that the heating modules (3), in particular their Heizenergiezufuhr and the residence time of the preforms (5) in the heating chambers (4), further determined on the basis of the in the method according to claim 12 individual correction values (35) are controlled or regulated.