Apparatus and method for forming plastic preforms into plastic containers with regulation of the pressure rise time

Abstract

An apparatus for forming plastic preforms into plastic containers having a transport device which transports the preforms to be formed along a predetermined transport path, wherein the transport device has a rotatable transport carrier on which a plurality of forming stations are arranged which each have a blow-molding device within which the preforms can be formed into the containers. The forming stations each have a pressurizing device which pressurizes the preforms with a flowable medium, i.e., compressed air, wherein the pressurizing device subjects the preforms to a preblowing pressure, at least one and preferably two intermediate blowing pressures, and a final blowing pressure. The apparatus has a detection device which is configured for detecting at least one value characteristic of the plastic container, wherein depending on this value characteristic of the container, the duration of the pressure rise time of at least one intermediate blowing pressure can be regulated.

Claims

1. An apparatus for forming plastic preforms into plastic containers with a transport device configured to transport the plastic preforms to be formed along a predetermined transport path, wherein the transport device has a rotatable transport carrier on which a plurality of forming stations are arranged which each have a blow molding device within which the plastic preforms are formed into the plastic containers, wherein the forming stations each have a pressurizing device configured to pressurize the plastic preforms with a flowable medium, wherein the pressurizing device is configured to pressurize the plastic preforms with a pre-blowing pressure, at least one intermediate blowing pressure and a final blowing pressure, and the apparatus has a regulating device which is configured for regulating a duration of a pressure rise time of at least one intermediate blowing pressure, wherein the apparatus has a detection device which is configured for detecting at least one value characteristic of the plastic container, wherein depending on the value characteristic of the plastic container, the duration of the pressure rise time of at least one intermediate blowing pressure is regulated.

2. The apparatus according to claim 1, wherein the apparatus has an evaluation device which is configured for evaluating and/or assessing the at least one characteristic value detected by the detection device for the plastic container in such a way that a conclusion can be drawn about the quality of the plastic containers.

3. The apparatus according to claim 2, wherein the evaluation device is configured to compare the at least one value characteristic of the plastic container detected by the detection device with predetermined and/or saved values.

4. The apparatus according to claim 3, wherein the detected values are compared with target values.

5. The apparatus according to claim 1, wherein the regulating device is smoothly displaceable between a minimum value and a maximum value of the pressure rise time.

6. The apparatus according to claim 1, wherein the detection device is an image recording device.

7. The apparatus according to claim 6, wherein the image recording device is a camera.

8. The apparatus according to claim 1, wherein the apparatus has a valve arrangement configured to control the application of the pre-blowing pressure, the at least one intermediate blowing pressure, and the final blowing pressure to the plastic containers.

9. A method for forming plastic preforms into plastic containers, wherein the plastic preforms to be formed are transported along a predetermined transport path, wherein a plurality of forming stations are arranged on a rotatable transport carrier, wherein the forming stations each have a blow molding device within which the plastic preforms are formed into the plastic containers, wherein the forming stations each have a pressurizing device which pressurizes the plastic preforms with a flowable medium, wherein the pressurizing device pressurizes the plastic preforms with a pre-blowing pressure, at least one intermediate blowing pressure and a final blowing pressure, and a regulating device regulates a duration of a pressure rise time of at least one intermediate blowing pressure, wherein at least one value characteristic of the plastic container is detected, wherein depending on the value characteristic of the plastic container, the duration of the pressure rise time of at least one intermediate blowing pressure is regulated.

10. The method according to claim 9, wherein the at least one value characteristic of the plastic container is compared with predetermined and/or saved values.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In the drawings:

[0037] FIG. 1 shows a schematic view of an apparatus for forming plastic preforms into plastic containers;

[0038] FIG. 2 shows a diagram of a blowing curve; and

[0039] FIG. 3 shows an example of an adjustment of the forming process.

DETAILED DESCRIPTION OF THE DRAWINGS

[0040] FIG. 1 shows an apparatus) for forming plastic preforms 10 into plastic containers 15. This apparatus 1 has a rotatable carrier 22 on which a large number of forming stations 4 is arranged. These individual forming stations 4 each have blow molding devices 82, which in their interior form a cavity for expanding the plastic preforms.

[0041] Reference sign 84 denotes a pressurization device which is used to expand the plastic preforms 10 to expand them. Reference sign 90 denotes a valve arrangement, such as a valve block, which preferably has a large number of valves that control the application of different pressure levels to the plastic preforms.

[0042] In a preferred embodiment of the method, first a pre-blowing pressure P1, then at least one intermediate blowing pressure Pi that is higher than the pre-blowing pressure, and finally a final blow molding pressure P2 that is higher than the intermediate blowing pressure Pi are applied to the plastic preforms. After expansion of the plastic containers, the pressures or compressed air are preferably returned from the container to the individual pressure reservoirs.

[0043] The reference sign 88 designates a stretching bar which serves to stretch the plastic preforms in their longitudinal direction, and the reference sign 30 designates stretching unit which controls the movement of the stretching bar. Preferably, all forming stations have such blow molds 82 along with stretching bars 88. The number of these forming stations is preferably between 2 and 100, preferably between 4 and 60, preferably between 6 and 40.

[0044] The plastic preforms 10 are fed via a feed device 62 such as, in particular, but not exclusively to a transport star of the apparatus, and the formed plastic containers 15 are removed via a removal device 64.

[0045] Reference sign 7 denotes a pressure supply device, such as a compressor or also a compressed-air connection. The compressed air is conveyed via a first connecting line 72 to a rotary distributor 74 and discharged therefrom via a second connecting line 76 to the annular channel 2a.

[0046] In addition to such annular channel 2a shown, further annular channels are preferably provided, which are, however, concealed by, e.g., lie underneath, the annular channel 2a in the illustration shown in FIG. 1. A plurality of annular channels are preferably arranged one above the other. Reference sign 98 denotes a third connecting line that delivers the compressed air to a forming station 4 or the valve assembly 90 thereof. Preferably, each of the annular channels is connected to all forming stations via corresponding connecting lines.

[0047] Reference sign 8 schematically denotes a clean room, which is preferably annular here and surrounds the transport path of the plastic preforms 10. Preferably, a (geometric) axis of rotation, with respect to which the transport carrier is rotatable, is arranged outside the clean room 8. Preferably, the clean room is sealed from the non-sterile environment by a sealing device, which preferably has at least two surge tanks.

[0048] The reference sign 52 denotes a detection device for detecting a characteristic value, such as an image of the plastic container. This detection device can also be arranged at one point on the device 1. As indicated by the dashed line, the detected characteristic value or the detected characteristic image is preferably transmitted wirelessly to an evaluation device 54 which evaluates the image in the manner described above, or compares it with values saved in the memory device 55. The reference sign 50 designates a regulating device, such as in this case a shift register, which is adjusted according to the result of the evaluation.

[0049] FIG. 2 shows a diagram of a blowing curve 110. The reference sign Vp designates the pre-blowing phase during which the pre-blowing pressure P1 is applied. The formation phase Ap is represented by the dashed lines, wherein the region within the solid line within the dashed line represents the application of the final blowing pressure P2, and the region to the left of the solid line (between the solid and dashed lines) represents the application of the intermediate blowing pressures Pi and Pi2. After the application of the final blowing pressure P2, it is held for a certain time. Subsequently, the used compressed air is recycled and the container is relieved, which is represented by the falling curve. The reference sign Rv designates the curve of the stretching bar.

[0050] FIG. 3 shows an example of an adjustment of the forming process. This is in particular an exemplary representation of the individual values on an operating terminal 100 of the device. In particular, the profile depicted in FIG. 2 is shown here.

[0051] As can be seen from the x-axis of FIG. 2 and the display 105 of FIG. 3, the pre-blowing phase Vp starts at 230 ms and lasts 115 ms, so that at 345 ms, the formation phase Ap starts which in turn lasts 280 ms and therefore ends at 625 ms.

[0052] The reference sign 50 designates the regulating device, such as in this case a slider which is displaceable as illustrated by the arrow A. This is adjusted so that the intermediate blowing pressures Pi, Pi2 are applied for 90 ms, which leads to a 99% effectiveness of the process. Preferably, the position of this regulating device is automatically adjusted and adapted using the described method or the described apparatus, in particular depending on a characteristic value and/or the quality of the plastic containers.

[0053] The applicant reserves the right to claim all features disclosed in the application documents as essential to the invention, provided that they are novel over the prior art individually or in combination. It is also pointed out that features which can be advantageous in themselves are also described in the individual figures. The person skilled in the art will immediately recognize that a particular feature described in a figure can be advantageous even without the adoption of further features from this figure. Furthermore, the person skilled in the art will recognize that advantages can also result from a combination of several features shown in individual or in different figures.

LIST OF REFERENCE SIGNS

[0054] 1 apparatus [0055] 2 transport device [0056] 2a annular channel [0057] 4 forming station [0058] 7 pressure supply device [0059] 8 clean room [0060] plastic preform [0061] plastic container [0062] 22 transport carrier [0063] stretch unit [0064] 50 regulation device [0065] 52 detection device [0066] 54 evaluation device [0067] 55 storage device 62 feed device [0068] 64 discharge device [0069] 72 first connecting line [0070] 74 rotary distributor [0071] 76 second connecting line [0072] 82 blow molding device [0073] 84 pressurizing device [0074] 88 stretching bar [0075] 90 valve assembly [0076] 98 third connecting line [0077] 100 operating terminal [0078] 105 display [0079] 110 Blowing curve [0080] A arrow [0081] Ap forming phase [0082] Vp pre-blowing phase [0083] P1 pressure P1, pre-blowing pressure [0084] Pi pressure Pi, intermediate blowing pressure [0085] Pi2 pressure Pi2, intermediate blowing pressure [0086] P2 pressure P2, final blowing pressure [0087] Rv curve of the stretching bar