APPARATUS AND METHOD FOR FORMING PLASTICS PREFORMS WITH CONTROLLED VALVE UNIT

Abstract

A method for forming plastic preforms into plastic containers, wherein the plastic preforms being transported along a predetermined transport path and being acted upon and expanded by a flowable medium during this transport, a controllable valve of a reducing station controlling the action of the flowable medium on a compressed-air reservoir, in particular an annular channel, and a desired target pressure being predetermined, with which the compressed-air reservoir is acted upon, this desired target pressure being taken into account in the control of the valve of the reducing station wherein an actual pressure is determined and this actual pressure is compared with the desired target pressure and, from this comparison, a correction value is determined which is taken into account and/or used in the control of the valve.

Claims

1. A method for forming plastic preforms into plastic containers, wherein the plastic preforms being transported along a predetermined transport path and being acted upon and expanded by a flowable medium during this transport, a controllable valve of a reducing station controlling the action of the flowable medium on a compressed-air reservoir, in particular on an annular channel, and a desired target pressure being predetermined, with which the compressed-air reservoir (74) is acted upon, this target pressure being taken into account in the control of the valve of the reducing station, wherein an actual pressure is determined and this actual pressure is compared with the target pressure and, from this comparison, a correction value is determined which is taken into account and/or used in the control of the valve.

2. The method according to claim 1, wherein the correction value results from a difference between the actual pressure and the target pressure.

3. The method according to claim 1, wherein, taking into account the correction value, a time is determined at which the valve of the reducing station is actuated and, in particular, a time is determined at which the valve of the reducing station switches between an open position and a closed position.

4. The method according to claim 1, wherein a plurality of forming stations is provided for forming plastic preforms and an actual pressure is determined for each of these forming stations.

5. The method according to claim 1, wherein the plastic preforms are subjected to several pressure stages for expansion and preferably the actual pressure is determined for at least one of these pressure stages.

6. The method according to claim 1, wherein the valve of the reducing station is a proportional valve.

7. The method according to claim 1, wherein the pressurised flowable medium is made available via a source of compressed air and preferably the pressure originating from this source of compressed air is reduced by a reducing station before the compressed air enters the compressed air reservoir.

8. The method according to claim 1, wherein the actual pressure is determined using at least one pressure measuring device which is arranged in a compressed air reservoir and/or using a plurality of pressure measuring devices which are assigned to individual forming stations.

9. The method according to claim 1, wherein the actual pressure is continuously detected.

10. The method according to claim 1, wherein the actual pressures, target pressures and/or correction values are preferably continuously recorded using a storage device.

11. The method according to claim 1, wherein an artificial intelligence is used to determine characteristic values of the device.

12. An apparatus for forming plastic preforms into plastic containers, comprising a transport device which transports the plastic preforms along a predetermined transport path and an application device which acts upon the plastic preforms during this transport with a flowable medium in order to expand them, the apparatus having a controllable valve which controls the admission of the flowable medium to a compressed-air reservoir, in particular an annular channel, and it being possible to preset a desired target pressure with which the compressed-air reservoir is admitted, a control device taking account of this desired target pressure in the control of this valve, wherein the device has a measuring device for determining an actual pressure, and a comparison device compares this actual pressure with the target pressure, and a processor device uses this comparison to determine a correction value which is taken into account in the control of the valve.

13. The apparatus according to claim 12, wherein the control device is adapted and designed to change a timing of the actuation of the valve of the reducing station taking into account the correction value.

14. A device according to claim 12, wherein the device comprises a reducing station which is configured for reducing a pressure originating from a pressure source and the valve is preferably a component of this reducing station.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Further advantages and embodiments can be seen in the attached figure. Thereby shows:

[0058] FIG. 1 a schematic representation of an apparatus according to the invention.

DETAILED DESCRIPTION OF THE DRAWINGS

[0059] FIG. 1 shows a roughly schematic representation of an apparatus 1 according to the invention for forming plastic preforms 10 into plastic containers and in particular plastic bottles. In particular, the device is a stretch blow-moulding machine. The reference sign 2 indicates a transport device such as a so-called blowing wheel, on which a plurality of forming stations 25 are arranged. These forming stations are preferably designed in the same way or have the same components. For reasons of clarity, however, this is only shown for two forming stations.

[0060] The reference sign 32 indicates a feeding device such as a transport star which feeds plastic preforms 10 to the forming device 1 and the reference sign 34 indicates a removal device which removes the blown plastic containers from the forming apparatus 1.

[0061] The reference sign 5 indicates a source of compressed air, such as a compressor, which provides compressed air and supplies it to the device via a line 52. Reference sign 7 indicates a rotary distributor that ultimately distributes the supplied compressed air to the individual forming stations 25.

[0062] The reference sign 72 indicates a connection line which connects a compressed air reservoir such as an annular channel 74 with the rotary distributor. Preferably, the device has at least two, preferably at least three such annular channels. The reference sign 6 identifies a reducing station such as a dome pressure regulator which reduces the pressure coming from the compressed air source 5. The reference sign 65 indicates a valve of this reducing station. This valve is preferably controlled in the process according to the invention.

[0063] The forming stations each have a application device 14, such as a blow nozzle, which acts upon the plastic preforms with compressed air. The reference sign 12 schematically indicates a valve which controls the compressed air supply to the plastic preform 10.

[0064] The reference sign 8 roughly schematically identifies an (optionally available) measuring device, more precisely a pressure detection device, which detects the actual (air) pressure (in particular inside the containers to be expanded). The reference sign 75 indicates a pressure measuring device which is assigned to the annular channel 74 and which determines the pressure of the flowable medium within the annular channel 74.

[0065] By means of an input device 28, a user can preset a target pressure for the machine. A comparison device 22 compares the measured actual pressure (preferably separately and assignable for each forming station) with the target pressure and preferably determines a difference between these pressures.

[0066] A processor device 30 determines a correction value from this difference, which is used by a control device 16 to control the individual valves of the conversion stations.

[0067] Preferably, a memory device 26 is also provided, which stores the measured pressures, preferably with an assignment to the respective forming stations and preferably also with a time value, preferably for each individual forming station.

[0068] The reference sign 6 indicates (roughly schematically) reducing station such as a dome pressure regulator, which reduces the air pressure coming from the compressed air source 5.

[0069] 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.