Method and apparatus for inspecting containers, including dust injection

Abstract

The present invention provides a method for inspecting a container (10), comprising: The method includes the steps of providing an unfilled container (10), introducing a powdery substance into the interior of the container, and optically inspecting the container with an inspection device (6).

Description

[Technical Field]

[0001] The present invention relates to a method and apparatus for inspecting containers, particularly plastic preforms, especially transparent plastic preforms. [Background technology]

[0002] It is known from the prior art that plastic material preforms are heated and fed in this heated state to a blow molding device, such as a blow molding machine, so that they are expanded from the blow molding machine in order to form plastic bottles. In this case, this type of plastic material preform is transparent, and it is also known that generally transparent plastic material preforms and other containers are typically inspected by optical methods, which aim to detect residues, foreign bodies, etc. that settle visually distinguishably from the background or transparent substrate.

[0003] Further characteristics such as size, quantity, material and the like of these foreign objects play an important role in how this type of foreign object can be recognized. Summary of the Invention

[0004] In part, the prior art has the drawback that liquid or highly viscous transparent or at least partially transparent foreign bodies are hardly or not detected at all. Typical examples are particle-bound, sticky oily or aqueous impurities. It is therefore an object of the present invention to improve the possibility of inspecting such containers. This is achieved according to the invention by the subject matter of the independent claims. Advantageous embodiments and developments are the subject matter of the dependent claims.

[0005] In the method for inspecting containers according to the present invention, unfilled containers are first provided, a powdery substance is introduced into the interior of the unfilled containers, and then an optical inspection of the containers is performed using an inspection device.

[0006] The invention therefore assumes that at least one inspection of the powdery substance is possible, in particular when this powdery substance remains attached to the inner wall of a container such as a plastic preform, so that the presence of a corresponding free-flowing or generally undesirable substance in the container can be concluded.

[0007] The supply of powdery substances or dusts with specific properties leads to the phenomenon of increased particle formation on the dirty zones of the container, these zones being optically more easily distinguished from adjacent zones. In particular, such particle formation can be determined on the walls of the container, especially on the walls that are subsequently expanded.

[0008] In a preferred method, the volume of the substance introduced into the interior of the container is less than 40% of the interior of the container, preferably less than 30% of the interior, preferably less than 20% of the interior, preferably less than 10% of the interior, preferably less than 5% of the interior space, which means that only a very small amount of powdered substance is introduced compared to the interior of the container.

[0009] The powdered substance is therefore in particular not a filling material that is filled into the container, but rather a test substance that is preferably at least partially removed again from the container or expelled together with the container into which it was introduced.

[0010] Manual testing by human eyes is possible, however the idea here is to propose an automated inspection method where possible procedures are considered.

[0011] Thus, in a preferred embodiment, the transport device transports the container to an insertion station where the powdery substance is introduced into the container, and / or the transport device transports the container with the powdery substance introduced into it to an inspection device.

[0012] In this case, it is also possible to provide a plurality of conveying devices for conveying the containers in individual conveying sections. Thus, for example, a first conveying device for conveying the containers to the insertion station can be selected from the group of conveying devices including chain conveyors, sorting rollers, conveyor rails, conveying stars, conveying discs, linear motor conveying devices, etc. Preferably, this conveying device conveys the containers, in particular plastic material preforms, in an individualized state.

[0013] A further transport device can transport the container from the insertion station to the inspection device, which may be selected from a group of transport devices including chain conveyors, sorting rollers, conveyor rails, transport stars, transport disks, linear motor transport devices, etc.

[0014] The transport device can have a gripping element for gripping the container. In a preferred embodiment, the insertion station moves with the container during transport. For example, the insertion station can be arranged on a movable, in particular rotatable, carrier. It is also conceivable that a plurality of such insertion stations are arranged on such a movable carrier.

[0015] Preferably, the container is further transported through the inspection device using a transport device, which and possibly also further transport devices may be selected from the group of transport devices comprising chain conveyors, sorting rollers, conveyor rails, transport stars, transport discs, linear motor transport devices, etc.

[0016] However, it is also possible that the insertion station is fixedly disposed along the transport path of the containers, and the containers are transported past this insertion station.

[0017] In a further preferred method, the inspection device inspects the walls of the container for the presence of powdery material thereon. As mentioned above, this can serve as an indication that an invisible material is present in the container, but that powdery material is attached to it. Therefore, from the presence of this powdery material on the walls of the container, it is possible to conclude that (undesirable) material is located in these containers.

[0018] In a preferred method, the container is a plastic container, however, the methods described herein can also be applied to other materials, and thus the container may be a glass container.

[0019] In a more preferred method, the container is a plastic preform.

[0020] Particularly preferably, the material of the container is an at least partially, preferably completely transparent material, in particular a material that is transparent to light in the visible spectral range.

[0021] In another preferred embodiment, the powdered substance is poured into the interior of the container, in this way a distribution of the substance inside the container is achieved, and preferably also a uniform adhesion to the inner walls of the container.

[0022] Preferably, the injection nozzle and the return air duct are arranged in a form-fitting or sealing manner at the container mouth.

[0023] Particularly preferably, the test dust is washed away with sufficient energy, preferably without the described adhesion, so that no or only minimal test dust remains in the container.

[0024] In another preferred embodiment, the powdered material is corundum or a material containing corundum. Corundum is characterized by the fact that it has a very high hardness.

[0025] In another preferred method, the powdered substance has a particle size of at least 10 μm, preferably at least 30 μm, more preferably at least 50 μm.In another preferred embodiment, the powdered substance has a particle size of less than 400 μm, preferably less than 300 μm, preferably less than 200 μm, particularly preferably less than 150 μm.Such particle size has been proven to be suitable for adhering to the inner wall of plastic containers in an easily detectable manner.

[0026] In a further preferred embodiment, the powdered substance is food-compatible, which is important since even with further methods it is not possible to exclude the possibility that small residues of the substance may remain in the container.

[0027] In another preferred method, the container containing the powdery substance is separated or cleaned, for example, even in the case of a good result, it is possible that the powdery substance or test dust is blown into a part of the container that has to be discarded after the automatic optical inspection, since the test dust cannot be completely removed in the subsequent dust removal device.

[0028] In this case, some degree of random sampling is carried out to check, for example, whether preforms contaminated with a substance are present within a certain margin of the plastic preforms.

[0029] Alternatively, test dust is injected into each container in order to discharge only contaminated containers under inspection control, whereby, particularly preferably, powdery substances can be removed sufficiently well in the subsequent dust removal step.

[0030] Thus, in this method, all plastic preforms or containers are inspected and then cleaned.

[0031] The present invention is further directed to an apparatus for inspecting containers, the apparatus comprising: a conveying device for conveying the containers along a predetermined conveying path; an insertion device for introducing a powdery substance into the containers; and an inspection device positioned downstream of the insertion device along the conveying path and for inspecting the containers containing the powdery substance.

[0032] It is therefore also proposed on the part of the device that powdery substances, in particular dust, are first introduced, for example blown, into the container by means of an insertion device and then these are inspected. The inspection device therefore serves in particular the purpose of inspecting containers with powdery substances, in particular checking whether certain surface areas, in particular the circumferential wall of the container, have been impacted with powdery substances in order to conclude the presence of undesirable substances in the container.

[0033] In another preferred embodiment, the apparatus comprises a manufacturing device for manufacturing the containers. Alternatively, a storage device for storing the containers may be provided.

[0034] In another preferred embodiment, the apparatus has a discharge device arranged downstream of the inspection device along the conveying path, the discharge device being suitable for and intended to discharge containers from the container flow. All defective containers can be rejected, particularly in response to the results of the inspection device. It is also possible for the discharge device to reject all containers containing powdery material.

[0035] In another preferred embodiment, the insertion device has a nozzle for injecting the powder. Particularly preferably, the insertion device has a reservoir in which the powdered substance is disposed. Furthermore, the insertion device can have an element such as a sieve, which allows the powdered substance to enter the plastic container in fine particle size.

[0036] In another preferred embodiment, the inspection device is an optical inspection device. The inspection device preferably inspects the container in a reflected or transmitted light manner. Preferably, recording is performed before injection (or generally, insertion) and after injection (or generally, insertion). Changes (in appearance or results of injection) are therefore particularly efficient to evaluate. Particularly preferably, the incident light inspection is a color recording.

[0037] The inspection equipment preferably inspects the containers during transport. The containers are preferably individualized. In this way, targeted discharge of specific containers is preferably possible.

[0038] Particularly preferably, the insertion device is a powder metering device. Preferably, such an insertion device, in particular a powder metering device, introduces a powdery substance into a gas mass flow, in particular a (sterile) air mass flow.

[0039] Preferably, the insertion device or powder metering device is designed so that the introduction of the powdered substance can be carried out intermittently and / or at predetermined time intervals. For example, it is possible to add the powdered substance to the gas mass flow intermittently and / or at predetermined time intervals. Alternatively or additionally, it is also possible to operate the gas mass flow intermittently and / or at predetermined time intervals.

[0040] In this way, it is possible to introduce the powdered substance only into individual plastic preforms.

[0041] Preferably, the gas used by the insertion instrument is selected from the group of gases containing CO2, N2, air, sterile air, gaseous disinfectants, mixtures thereof, and the like.

[0042] Alternatively, it is conceivable to mechanically drop the powder into the plastic preform (especially suspended) in a first step and to generate a distribution on the inner surface of the preform, preferably with small air pulses, in a second step. In an optional third step, an optical evaluation is carried out, which can then preferably be rinsed in an optional fourth step with a gas or liquid cleaning step.

[0043] Preferably, the powdered substance and / or the rinsing medium is compatible with the product to be subsequently filled, compatibility being understood to mean that the powdered substance does not affect certain properties of the filled product, such as in particular its shelf life or its taste. Furthermore, the rinsing medium may also be a gaseous rinsing medium.

[0044] Further advantages and embodiments will become apparent from the accompanying drawings. [Brief explanation of the drawings]

[0045] The drawings are as follows: [Figure 1] 1 shows a block diagram representation of an apparatus according to the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0046] 1 shows a block diagram representation of an apparatus 1 according to the invention for inspecting containers 10. Here, reference number 22 refers to an apparatus for producing plastic preforms, such as an injection molding machine. The plastic preforms produced in this apparatus can be transported to an insertion apparatus 4 via a conveying apparatus.

[0047] Alternatively, it is also possible to store the plastic preforms in a storage device 24 , for example a container, and to transport them from there to the insertion device 4 .

[0048] Reference number 2 broadly and diagrammatically indicates a conveying device, here conveying plastic preforms from an insertion device of an inspection device, where the apparatus 1 comprises a plurality of such conveying devices, conveying plastic preforms, or generally containers, from one station to another.

[0049] The dust is introduced into a container in the insertion device, which in this connection may have, for example, a nozzle for injecting a certain amount of powdery material into the container.

[0050] The container 10 containing the powdered material is then transferred from the insertion device to an inspection device, which can visually inspect the container and determine whether the powdered material has settled on the interior surfaces of the container.

[0051] Reference number 12 denotes a discharge device for discharging a particular container from the product stream, as indicated by arrow P1. It is possible that all containers into which powdery material has been introduced are discharged. However, it is also possible to discard only those containers that have been identified as defective, for example, those that an inspection device has detected as having powdery material on their inner walls.

[0052] Reference number 14 denotes a cleaning device, such as a blowing device, for removing powdery material from the container. In this process, the powdery material can be blown out of the container, for example. It is also conceivable to transport the container upside down for this cleaning, for example with its mouth facing down.

[0053] Alternatively, washing with a liquid is also possible.

[0054] Reference numeral 16 denotes a heating device for heating the plastic preforms, and reference numeral 18 denotes a molding device for molding the plastic preforms into plastic containers.

[0055] Reference numeral 20 denotes a control device for controlling the entire system, which can, for example, control the discharge devices in such a way as to discharge a particular container 10 from the product stream.

[0056] In contrast to FIG. 1, it is also possible for the insertion device to be arranged on a separate transport branch, and for all containers passing through the insertion device to be subsequently ejected.

[0057] The applicant reserves the right to claim all features disclosed in this application as essential to the invention, provided that they, individually or in combination, are novel over the prior art. It is also noted that features that may be advantageous in themselves are also depicted in the individual figures. Those skilled in the art will immediately recognize that a particular feature depicted in a figure may be advantageous even without adopting additional features from this figure. Furthermore, those skilled in the art will recognize that advantages can also be obtained from a combination of several features depicted in individual figures or in different figures. [Explanation of symbols]

[0058] 1 device 2. Conveying equipment 4 Insertion equipment 6. Inspection equipment 10 containers 12 Discharge equipment 14 Cleaning equipment, blowing equipment 16 Heating equipment 18 Molding equipment

Claims

1. A method for inspecting a container (10), comprising: Providing an unfilled container (10); introducing a powdered substance into the interior of the container; inspection, in particular optical inspection, of said container by an inspection device (6), The method, wherein the inspection device (6) inspects the walls of the container (10) for the presence of the powdery substance thereon.

2. 2. The method of claim 1, wherein the volume of the powdered substance introduced into the interior of the container (10) is less than 20% of the interior of the container (10).

3. 3. The method according to claim 1 or 2, characterized in that a transport device (2) transports the container to an insertion station (4) where the powdered substance is introduced into the container, and / or the transport device (2) transports the container with the introduced powdered substance to the inspection device (6).

4. The method according to any one of claims 1 to 3, characterized in that the container is a plastic container (10), in particular a plastic preform (10).

5. Method according to any one of claims 1 to 4, characterized in that the powdered substance is introduced, in particular blown, into the interior of the container (10).

6. 6. The method according to any one of claims 1 to 5, characterized in that the powdered substance is or comprises corundum.

7. 7. The process according to any one of claims 1 to 6, characterized in that the powdered substance has a particle size of at least 10 μm, preferably at least 30 μm, preferably at least 50 μm, and / or the powdered substance has a particle size of at most 400 μm, preferably at most 300 μm, preferably at most 200 μm, particularly preferably at most 150 μm.

8. Method according to any one of claims 1 to 7, characterized in that the container (10) containing the powdery substance is separated and / or washed.

9. 1. An apparatus for inspecting a container (10), comprising: a conveying device (2) for conveying the container (10) along a predetermined conveying path; an insertion device (4) for introducing a powdery substance into the container; and an inspection device (6) disposed downstream of the insertion device (4) along the conveying path and for inspecting the container containing the powdery substance, the inspection device (4) inspecting a wall of the container (10) to determine whether powdery substance has adhered to the wall.

10. 10. Apparatus according to claim 9, characterized in that the apparatus comprises a discharge device (12) arranged along the conveying path after the inspection device (6), the discharge device being suitable for discharging the container from the flow of containers.

11. 11. Apparatus according to claim 9 or 10, characterized in that the insertion device is a powder metering device.

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