BLOW-MOLDING MACHINE WITH PRESSURE CONTROL DURING THE BLOW-MOLDING PROCESS

Abstract

A device for forming plastic parisons into plastic containers includes at least one forming station arranged on a conveying device and configured to form plastic parisons into plastic containers by applying a gaseous medium, the forming station includes an application device configured to apply the flowable medium to the plastic parisons, and includes a pressure supply device and/or is in fluidic connection with a pressure supply device configured to provide the flowable medium at a prespecified pressure, wherein pressure provided by the pressure supply device is greater than pressure required and/or used for the application to the plastic parisons, wherein the device includes at least one valve device which controls application to the plastic parisons, which valve device is configured to interrupt the supply of air into the container when the pressure of the flowable medium within the container has reached a prespecified pressure level.

Claims

1. A device for forming plastic parisons into plastic containers and in particular into plastic bottles, having a conveying device which is configured for conveying the plastic parisons along a prespecified conveying path, wherein at least one forming station is arranged on this conveying device and is configured to form the plastic parisons into the plastic containers by applying a gaseous medium, wherein the forming station comprises an application device configured to apply the flowable medium to the plastic parisons, wherein the device also comprises a pressure supply device and/or is in fluidic connection with a pressure supply device, which is configured to provide the flowable medium to the application device at a prespecified pressure, wherein the pressure provided by the pressure supply device is greater than the pressure required and/or used for the application to the plastic parisons, wherein the device comprises at least one valve device configured to control the application to the plastic parisons, wherein this valve device is configured to interrupt the supply of air into the container when the pressure of the flowable medium within the container has reached a prespecified pressure level.

2. The device according to claim 1, wherein the device comprises at least one pressure detection device configured to determines a pressure in the plastic parison that is to be expanded.

3. The device according to claim 1, wherein the valve device has a switching time that is less than 40 ms, preferably less than 30 ms, preferably less than 25 ms, preferably less than 20 ms and particularly preferably less than 15 ms.

4. The device according to claim 1, wherein the device comprises a pressure control device which is configured to apply a plurality of different pressure stages to the plastic parison.

5. The device according to claim 1, wherein the device comprises at least one pressure reservoir and preferably a plurality of pressure reservoirs in which the flowable medium can be stored under different pressures.

6. The device according to claim 1, wherein the device comprises a pressure supply device, which is arranged in particular in a stationary manner and generates the pressurized medium, and preferably a distribution device, which conducts the medium into a reservoir arranged on the conveying device.

7. A method for forming plastic parisons into plastic containers and in particular into plastic bottles, wherein a conveying device, which conveys the plastic parisons along a prespecified conveying path, and wherein with a forming station arranged on this conveying device, the plastic parisons are formed into the plastic containers by application of a gaseous medium, wherein the forming station comprises an application device which applies the flowable medium to the plastic parisons, wherein the device also comprises a pressure supply device and/or is in fluidic connection with a pressure supply device, which provides the flowable medium at a prespecified pressure to the application device, wherein the pressure provided by the pressure supply device is greater than the pressure required and/or used for the application to the plastic parisons, wherein the device comprises at least one valve device which controls the application to the plastic parisons, wherein this valve device interrupts the supply of air into the plastic container when the pressure of the flowable medium within the plastic container has reached a prespecified pressure level.

8. The method according to claim 7, wherein at least from time to time, an internal pressure in the plastic parison or plastic container that is to be expanded and/or a flow of the flowable medium flowing into the plastic parison is measured.

9. The method according to claim 7, wherein the valve device is controlled taking into account the internal pressure.

10. The method according to claim 7, wherein a plurality of pressure stages is applied to the plastic parison and/or the plastic container.

11. The method according to claim 7, wherein a pressure profile is measured within a period in which a closure of the valve device takes place and the presence of leakages is preferably deduced from this pressure profile.

12. The method according to claim 7, wherein an opening time of the valve device is determined.

13. The method according to claim 7, wherein the plastic parisons are expanded with a plurality of forming stations and these forming stations in each case comprise valve devices which control the application to the plastic parisons, wherein these valve devices interrupt the supply of air into the container when the pressure of the flowable medium within the container has reached a prespecified pressure level.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Further distribute embodiments emerge from the accompanying drawings: These show:

[0063] FIG. 1 a diagram of a device according to the internal prior art; and

[0064] FIG. 2 a diagram of a device according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0065] FIG. 1 shows a schematic representation of a device 100 according to the internal prior art of the applicant. In this case, a schematically illustrated conveying device is provided, which is denoted by the reference sign 2 and on which a plurality of forming stations 20 is arranged.

[0066] These forming stations 20 each have side parts 26 and a base part 28, which together form a cavity (not shown) within which the plastic parisons (not shown) are blown to form the containers. The conveying device is here (just as in the case of the invention) a carrier rotatable about an axis of rotation M.

[0067] The reference number 22 designates an application device which is here brought up to an opening in the plastic parison in order to apply compressed air to the latter. The reference number 30 designates a valve block which has a plurality of valves in order to supply the compressed air to the plastic parisons in different pressure stages.

[0068] The reference sign 24 designates a drive for a stretching rod 25 which is inserted into the plastic parison in order to serve the latter in its longitudinal direction.

[0069] In the prior art, the compressed air is distributed via a central air supply and a rotary distributor 18 to a plurality of annular channels, 32, 34, 36 and 38. The reference number 102 designates a reducing device which reduces the supplied pressure in order to supply, for example, the annular channel 32. According to the prior art, the compressed air is thus present in the annular channel to the required extent or at the required pressure. The reference number 16 designates a carrier of the device.

[0070] FIG. 2 schematically shows a device according to the invention. It can be seen that the reducing stations 102 are missing here, i.e., the ring channel 32 is supplied at a greater pressure than is actually required for expanding the plastic parisons. However, the valve block 30 here has at least one fast-switching valve or a fast-switching valve device 12, which causes the corresponding valve device to be closed (or the air supply via this valve device to be interrupted when a certain pressure is present within the container). For this purpose, internal pressure in the container is determined (in particular continuously) by means of a measuring device 14.

[0071] The reference sign 35 designates a pressure supply device. This can be, for example, a compressor (in particular arranged stationary) or else a pressure outlet in a machine hall.

[0072] 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.