Apparatus and method for heating plastic preforms with adjustment of heating power

Abstract

Disclosed is a method for heating plastic preforms, wherein the plastic preforms are transported within a heating device along a predetermined transport path and are heated to a predetermined temperature during this transport by a plurality of heating devices arranged along the transport path, and wherein a heating power of the heating devices impinging on the plastic preforms can be varied. The heating power of the heating devices impinging on the plastic preforms is controlled depending on a transport speed of the plastic preforms.

Claims

1. A method for heating plastic preforms, wherein the plastic preforms are transported along a predetermined transport path within a heating device and are heated to a predetermined temperature during this transport by a plurality of heating devices arranged along the transport path, and wherein a heating power of the heating devices impinging on the plastic preforms can be varied, wherein the heating power of the heating devices impinging on the plastic preforms is controlled depending on a transport speed of the plastic preforms.

2. The method according to claim 1, wherein the heating power of each heating device and/or also of adjacent heating devices is controlled and/or changed individually and/or independently of each other.

3. The method according to claim 1, wherein the heating power of the heating devices and/or the transport speed of the plastic preforms is continuously controlled.

4. The method according to claim 1 wherein at least one heating device is displaceably arranged along the transport path of the heating device.

5. The method according to claim 1, wherein an internal and/or external temperature of the plastic preforms is detected within the heating device and this temperature is used to control the heating power of the heating devices.

6. The method according to claim 1, wherein the heating power is controlled via at least a first and a second corner recipe and is linearly interpolated, wherein the first corner recipe containing a first heating power and the second corner recipe containing a second heating power.

7. An apparatus for heating plastic preforms, having a heating device within which the plastic preforms are transported along a predetermined transport path by a transport device, wherein the plastic preforms are heated to a predetermined temperature during transport by a plurality of heating devices arranged along the transport path wherein a heating power of the heating devices which impinges on the plastic preforms is changeable, wherein the apparatus has a control and/or regulating device configured to regulate the heating power of the heating devices impinging on the plastic preforms depending on a transport speed of the plastic preforms.

8. The apparatus according to claim 7, wherein the heating device has at least one temperature sensor configured to detect an internal and/or an external temperature of the plastic preforms.

9. The apparatus according to claim 8, wherein the heating power of the heating devices can be controlled depending on the temperature detected by the temperature sensors.

10. The apparatus according to claim 7, wherein no heating devices are arranged on at least one section of the transport path of the heating device.

11. The apparatus according to claim 7, wherein the heating devices are selected from a group of heating devices consisting of IR lamps, microwave heating devices and laser arrays.

12. An installation for heating plastic preforms, having a transport device which transports the plastic preforms along a predefined transport path, wherein the plastic preforms are heated to a predefined temperature during transport by a plurality of heating devices arranged along the transport path, and wherein a forming device for forming plastic preforms into plastic containers is arranged downstream of the installation for heating, wherein the installation has a control and/or regulating device which regulates the heating power of the heating devices impinging on the plastic preforms depending on a transport speed of the plastic preforms and/or the forming device can be controlled and/or regulated depending on this transport speed.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Further advantages and embodiments can be seen in the attached drawings.

[0042] In the drawings:

[0043] FIG. 1 shows a first schematic embodiment of an apparatus according to the invention for heating plastic preforms;

[0044] FIG. 2 shows a schematic diagram for a heating profile of a plastic preform depending on time and energy;

[0045] FIG. 3 shows a further schematic diagram for a heating profile of a plastic preform depending on time and energy;

[0046] FIG. 4 shows a further schematic diagram for a heating profile of a plastic preform depending on time and energy; and

[0047] FIG. 5 shows a second schematic embodiment of an apparatus according to the invention for heating plastic preforms.

DETAILED DESCRIPTION OF THE INVENTION

[0048] FIG. 1 shows a first schematic embodiment of an apparatus 1 according to the invention for heating plastic preforms 10. In this embodiment, the apparatus 1 has a heating device 5 and a forming device 6. The plastic preforms 10 heated within the heating device 5 are transferred to the forming device 6 by means of a transport starwheel 12.

[0049] The plastic preforms 10 are transported along a predetermined transport path T through the heating device 5 by a transport device 2 and are heated to a predetermined temperature during transport by a plurality of heating devices H1...H12 arranged along the transport path T. For this purpose, the transport device 2 has a plurality of holding devices (not shown) for holding the plastic preforms.

[0050] The reference sign 3 indicates a control and/or regulating device for regulating or changing the heating power of the heating devices H1...H12. Furthermore, it can be seen that no heating devices are arranged within a curved section of the transport device 2, which is preferably a compensation zone E1. Furthermore, the transport starwheel 12 forms a second such compensation zone E2. The temperature of the plastic preforms 10 preferably remains constant in the compensation zones E1, E2 or at least does not change significantly.

[0051] FIG. 2 shows a schematic diagram for a heating profile of a plastic preform depending on time and energy. The temperature profile is shown depending on time or the individual heating devices H1...H12. In this example, the heating devices H1...H3, H5, H6 and H9...H12 are set to a heating power of 80%, while the heating devices H4, H7 and H8 are completely switched off. It can also be seen that the energy or temperature of the preforms remains constant in the switched-off heating devices and the compensation zones E1 and E2, while the temperature in the heating devices H1...H3, H5, H6 and H9...H12 increases and in particular rises linearly.

[0052] The time t=0 indicates the time at which the heated plastic preform is transferred to the blow moulding machine and the time t=SH1 indicates the time at which the preform is at the first heating device H1. Accordingly, the time t=SH2 indicates the time at which the preform is at the second heating device H2.

[0053] FIG. 3 shows a further schematic diagram for a heating profile of a plastic preform depending on time and energy. The course of the solid line corresponds to the course shown in FIG. 2.

[0054] The dashed line is the temperature profile of the preform with changed heating capacities of the heating devices H1...H12. The lower, likewise dotted table shows that the heating devices H1 and H2 are switched off and the power of the heating devices H3...H12 has been changed to 70%.

[0055] The heating power was thus reduced compared to the solid line/table, since the plastic preforms were transported through the heating device at a lower transport speed and thus remained longer in front of the individual heating devices.

[0056] The diagram illustrates that despite the change in speed, an almost identical heating profile is possible over time and, in particular, an identical temperature at the end.

[0057] FIG. 4 shows a further schematic diagram for a heating profile of a plastic preform depending on time and energy. Here, too, the solid line corresponds to the curve shown in FIG. 2.

[0058] FIG. 4 shows in particular another possibility of adapting the heating power of the heating devices H1...H12, but which again results in an approximately identical heating profile, as illustrated by the dashed line. The associated (dashed) table shows that in this example the heating devices H1, H2, H8 and H9 are completely switched off and the remaining heating devices, unlike in the example shown in FIG. 3, have different heating powers. The heating device H3 is operated at 30%, the heating devices H4 and H5 at 81%, the heating device H6 at 35%, the heating devices H7 and H12 at 90% and the heating devices H10 and H11 at 80%.

[0059] FIGS. 3 and 4 illustrate in particular that when the transport speed is changed by the heating device, almost similar temperature profiles with identical final temperature can still be produced on the plastic preforms by different settings of the heating power of the heating devices.

[0060] FIG. 5 shows a second schematic embodiment of an apparatus 1 according to the invention for heating plastic preforms 10. The apparatus 1 shown here corresponds essentially to the apparatus shown in FIG. 1, so that reference is no longer made here to the reference signs already included in the description of FIG. 1.

[0061] Unlike the embodiment shown in FIG. 1, however, the apparatus here also has several temperature sensors 7 which can detect an internal and/or external temperature of the plastic preforms 10. Such a temperature sensor 7 could, for example, also be arranged on the transport starwheel 2, as can be seen in FIG. 5. The arrangement of the temperature sensors in the apparatus is exemplary and not limited to this arrangement. Rather, they can be arranged at any point in the apparatus.

[0062] Furthermore, in FIG. 5 the heating device H13 is displaceably arranged, as illustrated by the arrows. The arrangement of this movable heating device is not limited to the arrangement shown. Rather, any other heating device can be arranged in a displaceable manner or the heating device can also have several displaceable heating devices.

[0063] The applicant reserves the right to claim all features disclosed in the application documents as essential to the invention, provided they are individually or in combination new compared to the prior art. It is further pointed out that the individual figures also describe features which may be advantageous in themselves. The skilled person immediately recognises that a certain feature described in a figure can also be advantageous without adopting further features from this figure. Furthermore, the skilled person recognises that advantages can also result from a combination of several features shown in individual figures or in different figures.

TABLE-US-00001 List of reference signs 1 apparatus 2 transport device 3 control and/or regulation device 5 heating device 6 forming device 7 temperature sensor 10 plastic preforms 12 transport starwheel E1, E2 compensation zone H1...H13 heating devices T transport path