Apparatus for heating plastic preforms by means of microwaves

Abstract

An apparatus is provided for heating plastic preforms, having a plurality of resonator units, into which in each case plastic preforms can be introduced in order to heat the latter, having at least one microwave generating unit for generating microwaves, and having a feed device for feeding to at least one resonator unit the microwaves generated by the microwave generating unit, and having at least one rectifier unit for providing a rectified voltage. Further, at least one rectifier unit provides voltage for operating at least two resonator units.

Claims

1. An apparatus for heating plastic preforms in a process, the apparatus having a plurality of resonator units, into which in each case plastic preforms are introduced in order to heat the latter, having at least one microwave generating unit for generating microwaves, and having at least one feed device for feeding to at least one resonator unit of the plurality of resonator units the microwaves generated by the at least one microwave generating unit, and having at least one rectifier unit for providing a rectified voltage, wherein the at least one rectifier unit provides voltage for operating at least two resonator units of the plurality of resonator units and wherein the plurality of resonator units themselves are arranged in a stationary manner and the individual plastic preforms could in each case be pushed through stationary resonator units and be heated in the process.

2. The apparatus according to claim 1, further comprising a transport device for at least one of introducing the plastic preforms into the plurality of resonator units and for taking the plastic preforms out of the plurality of resonator units.

3. The apparatus according to claim 1, further comprising at least one high voltage generating unit for operating a generator of high frequency voltage.

4. The apparatus according to claim 3, wherein the at least one high voltage generating unit provides high voltage for operating at least two resonator units of the plurality of resonator units.

5. The apparatus according to claim 1, wherein at least one microwave generating device generates microwaves for operating at least two resonator units of the plurality of resonator units.

6. The apparatus according to claim 1, further comprising at least one transport device that transports the plurality of resonator units along a predefined transport path.

7. The apparatus according to claim 1, wherein the at least one microwave generating unit is selected from a group of microwave generating units which includes magnetrons, klystrons or solid-state sources.

8. The apparatus according to claim 1, wherein the at least one rectifier unit includes a central rectifier unit, and the central rectifier unit and a central high voltage generating unit are arranged which supply all resonator units that are present.

9. The apparatus according to claim 8, wherein the output of the central rectifier unit and the central high voltage generating unit are distributed among the microwave generating units of the individual resonator units.

10. The apparatus according to claim 1, wherein the at least one rectifier unit includes a central rectifier unit, and the central rectifier unit a central high voltage generating unit and a central microwave generating unit are arranged which supply all resonator units that are present and the microwave radiation is distributed among the plurality of resonator units.

11. The apparatus according to claim 10, wherein the rectifier unit is arranged in a stationary manner and the rectified voltage is transmitted to the high voltage generating unit and from the latter to the microwave generating unit and form the latter to the resonator unit.

12. The apparatus according to claim 1, wherein in each of the resonator devices a base reflector is provided which reflects microwave radiation onto the base regions of the plastic preforms.

13. The apparatus according to claim 10, wherein the central microwave generating unit generates from a high voltage the microwave power for the entire system.

14. The apparatus according to claim 1, wherein the at least one rectifier unit is arranged in a stationary manner and the rectified voltage is transmitted to movable resonator units of the plurality of resonator units.

15. The apparatus according to claim 10, wherein the central microwave generating unit is arranged in a movable manner in such a way as to move jointly with the resonator units.

16. The apparatus according to claim 10, wherein the microwave radiation to the individual resonator units is switched on or off via suitable switching devices.

17. The apparatus according to claim 2, wherein the transport device has a rotating device which brings about a rotation of the plastic preforms about their longitudinal axis.

Description

BRIEF DESCRIPTION

(1) Some of the embodiments will be described in detail, with reference to the following figures, wherein like designations denote like members, wherein:

(2) FIG. 1 shows an apparatus according to the prior art;

(3) FIG. 2 shows an apparatus according to the invention in a first embodiment;

(4) FIG. 3 shows an apparatus according to the invention in a second embodiment; and

(5) FIG. 4 shows an apparatus according to the invention in a third embodiment.

DETAILED DESCRIPTION

(6) FIG. 1 schematically shows an apparatus 1 for heating plastic preforms 10. Here, a total of n stations 20 are provided, which are each embodied separately. Each individual station has a resonator unit 2a, 2b, 2c, which is in each case supplied with microwaves from microwave generating devices 4a, 4b, 4c via waveguides 6. Preferably, these resonator units are arranged in a movable manner. The individual stations 20 may (as also in the embodiments discussed below) be arranged on a common carrier, in particular a rotatable carrier (not shown).

(7) Reference 12 denotes a rectifier unit which rectifies (DC) mains voltage (AC). This rectified voltage is respectively fed to high voltage sources or high voltage generating units 8a, 8b, 8c and these in turn generate high voltage HV. This high voltage is transmitted or fed to the individual microwave generating devices 4a, 4b, 4c.

(8) FIG. 2 shows a first embodiment of an apparatus according to embodiments of the invention. Instead of the three separate rectifier units shown in FIG. 1, here just one rectifier unit 12 is provided, which in this case supplies all the high voltage generating devices 8a, 8b and 8c with high voltage. It is possible here that the rectifier unit is arranged in a stationary manner, so that the output voltage thereof is fed to the individual high voltage sources 8a, 8b, 8c via rotary distributors (for example a slip ring). Reference 16 denotes such a rotary distributor. It can be seen that here two positions of this rotary distributor are conceivable.

(9) The plastic preforms are pushed along their longitudinal direction L into the resonator units 2a, 2b, 2c and are also taken out of the resonator units along this longitudinal direction L. Reference 18 denotes a movement device which brings about this movement of the plastic preforms 10 along their longitudinal direction L. It is preferred that each station 20 has such a movement device 18 (for instance in the form of a linear motor). The movement of the plastic preforms 10 relative to the resonator units 2a, 2b, 2c can thus be controlled individually for the individual stations. In addition, as mentioned above, the plastic preforms 10 can also be rotated about this longitudinal direction L.

(10) FIG. 3 shows a further embodiment of an apparatus according to embodiments of the invention. In this embodiment, not only a central rectifier unit is provided, but also a central high voltage source. This central high voltage source supplies each of the individual microwave generating devices 4a, 4b, 4c with high voltage. In this embodiment, a total of three positions of a rotary distributor 16 would be conceivable, two of these positions being respectively shown by the dashed-line rectangles. All the units shown could thus be arranged on the rotating part, but it would also be conceivable that the rectifier unit 12 is arranged centrally and in a stationary manner, as well as the high voltage source 8.

(11) FIG. 4 shows a further embodiment of the apparatus according to embodiments of the invention. In this embodiment, a central rectifier unit and a central high voltage supply device and a central microwave generating device are provided. This central microwave generating device generates microwaves which are respectively distributed among the individual resonators 2a, 2b and 2c via several waveguides 6. Reference 16 again shows the possible positions of the rotary distributor. Here, too, it would also be conceivable that the high voltage generating device and the microwave generating device are arranged either in a stationary manner or in a movable and/or rotatable manner.

(12) The applicant reserves the right to claim as essential to the invention all the features disclosed in the application documents in so far as these are novel individually or in combination with respect to the prior art. It is also pointed out that also features which may be advantageous individually have been described in the individual figures. A person skilled in the art is immediately aware that a particular feature described in one figure can also be advantageous even without taking further features from this figure. A person skilled in the art is also aware that advantages may also arise through a combination of multiple features shown in individual figures or in different figures.

LIST OF REFERENCES

(13) 1 apparatus for heating plastic preforms 2a, b, c resonator units 4a, b, c microwave generating unit 6 feed device, waveguide 8a, b, c high voltage generating unit 10 plastic preform 12 rectifier unit 16 rotary distributor 18 movement device 20 station L longitudinal direction