METHOD AND DEVICE FOR OPTICALLY TESTING HOLLOW BODIES

Abstract

The invention relates to a method for optically testing containers, in which a container (10) is conveyed by means of a transport device (30), whereby an image of a side wall surface of the container (10) is generated by means of an inspection unit (40) comprising a camera unit (20) and an illumination unit (34). An inspection volume (24) is spanned by several correspondingly arranged inspection units (40), in which an image of the entire side wall surface (26) of the container (10) is generated in a transmitted light method, an incident light method and/or a dark-field method.

Claims

1. Method for optical testing of hollow bodies, in which a hollow body is conveyed by means of a transport device at a transport speed, whereby an image of a side wall surface of the hollow body is generated by means of an inspection unit comprising at least one camera unit and at least one illumination unit, characterized in that a plurality of inspection units are arranged so that an inspection volume is able to be spanned, in which an image of the entire side wall surface of the hollow body as well as a bottom and a mouth region is generated in a transmitted light method, an incident light method and/or a dark field method.

2. Method according to claim 1, characterized in that four inspection units span a largely cuboid inspection volume, whereby optical axes of substantially diagonally opposite inspection units lie on a line or offset from one another.

3. Method according to claim 1, characterized in that the camera unit of an inspection unit is designed as a line scan camera, whereby the longitudinal axis of the line scan camera is aligned parallel to the longitudinal axis of the hollow body.

4. Method according to claim 1, characterized in that each inspection unit comprises an illumination unit for illumination of the hollow body, which is arranged to emit light in the form of a light strip parallel to the longitudinal axis of the hollow body.

5. Method according to claim 1, characterized in that the camera unit of the inspection unit is arranged to take a serial sequence of pictures in each time interval, which, at a given transport speed, represents a distance corresponding to a fraction of the size of the container.

6. Method according to claim 1, characterized in that camera unit and illumination unit of an inspection unit are positioned relative to one another and are able to be activated in such a way that the hollow body in the inspection volume is able to be inspected using the incident light method.

7. Method according to claim 1, characterized in that camera unit and illumination unit of opposite inspection units are positioned relative to one another and are able to be activated in such a way that the hollow body in the inspection volume is able to be inspected using the transmitted light method.

8. Method according to claim 1, characterized in that a filter element is arranged in the beam path of the light of an inspection unit.

9. Method according to claim 8, characterized in that the filter element is a polarizing filter.

10. Method according to claim 1, characterized in that the hollow body is inspected with further inspection units for inspecting a threaded area, the camera unit comprising telecentric optics and/or the illumination unit configured for telecentric illumination.

11. Method according to claim 1, characterized in that the hollow body is inspected by means of an inspection unit for checking the contour and checking for slugs.

12. Method according to claim 1, characterized in that the hollow body is inspected by means of an infrared inspection unit.

13. Device for optically testing hollow bodies, comprising a transport device for conveying the hollow body, and at least one inspection unit, whereby the inspection unit comprises at least one camera unit and at least one illumination unit for imaging a side wall surface of the hollow body, characterized in that the device is configured in such a way that it comprises a plurality of inspection units, so that the entire side wall surface of the hollow body as well as a bottom and a mouth region are able to be imaged by means of the inspection units in transmitted light method, incident light method and/or dark field method.

14. Device according to claim 13, characterized in that each inspection unit comprises the camera unit, the illumination unit and at least one filter element, positioned and configured relative to one another in order to inspect the hollow body in the incident light method.

15. Device according to claim 13, characterized in that a plurality of inspection units are positioned and configured relative to one another so as to inspect the hollow body in the transmitted light method.

16. Device according to claim 13, characterized in that the camera unit is a line scan camera, whereby a longitudinal axis of the line scan camera is aligned parallel to the longitudinal axis of the hollow body.

17. Device according to claim 16, characterized in that a width of the sensor of the line scan camera is at least equal to the length of the hollow body.

18. Device according to claim 13, characterized in that the illumination unit is arranged to emit light in the form of a light strip corresponding to a length of the hollow body parallel to the longitudinal axis of the hollow body.

19. Device according to claim 13, characterized in that a filter element is arranged in the beam path of the light emitted from the illumination unit.

20. Device according to claim 19, characterized in that the filter element is a polarizing filter.

21. Device according to claim 13, characterized in that one of the inspection units comprises a camera unit with telecentric optics and/or an illumination unit configured for telecentric illumination.

22. Device according to claim 21, characterized in that one of the further inspection units is configured as an infrared inspection unit for inspecting the hollow body by means of infrared radiation.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Embodiment variants of the present invention will be described in the following with reference to examples. The examples of the embodiments are illustrated by the following enclosed figures:

[0041] FIG. 1 shows schematically representations of different containers to be tested;

[0042] FIG. 2 shows schematically a lateral view of a container to be tested;

[0043] FIG. 3 shows schematically a lateral view of a first preferred embodiment of a device according to the present invention;

[0044] FIG. 4 shows schematically a view of a region of the first preferred embodiment of the invention; and

[0045] FIG. 5 shows schematically a lateral view of a second preferred embodiment of the present invention.

PREFERRED EMBODIMENTS OF THE INVENTION

[0046] In the following detailed description of the preferred embodiments of the invention, only the testing of containers is shown. It should be noted, however, that the present invention also relates, as it were, to the testing of container closures and/or preforms for the manufacture of containers and that the following description is not intended to be construed in a limiting way.

[0047] FIG. 1 shows schematically a plurality of containers 10 whose integrity and quality are to be tested in each case by means of the present invention. The containers 10 shown according to FIG. 1 differ not only in size and shape, i.e. whether they have a round, oval and/or angular cross-section, but also in whether they are at least partially made of a transparent or opaque material and whether they may have imprints or labels at least on their side surfaces. A longitudinal axis of the container 10 is designated by 11. Furthermore, the containers 10 to be tested may also include handles, grips, etc., so that their contour may also vary. Now shown in FIG. 1 are containers 10, which can largely also be referred to as bottles. The variety of containers 10 to be tested can also include tubes, cans, canisters or other containers, largely known from the chemical, food, cosmetics, and pharmaceutical sectors.

[0048] FIG. 2 shows on an example of a basic shape of a container 10 to be tested those regions that can be subjected to an inspection. Basically, a container 10 includes a neck region 14 possibly with a threaded region 12, a transition region 13, a body region 16 and a bottom region 18. The inspection method and the inspection device according to the invention are arranged to inspect the container 10, i.e. at least the entire side wall surface 26 of the container 10, as indicated in FIG. 2, by a schematically shown camera unit 20.

[0049] FIG. 3 shows a schematic top view of a first embodiment of a device 100 for optical inspection of containers 10 according to the invention, which can be used to realize the method according to a preferred embodiment of the invention. The container 10 to be tested is conveyed into the device 100 by means of a transport device 30, whereby a first movable conveyor belt 31 is provided, the length L of which is selected such that the container 10 can be transported along substantially the entire length of the device 100. The drive means for activating the transport device 30 are only indicated by conveyor rollers and are not described in detail. Likewise not shown in detail are any light barriers to be arranged, which track the transport of the container 10 and are used to trigger certain units, as well as a measuring unit for determining the transport speed of the container 10.

[0050] The container 10, which is introduced into the device 100 along the transport direction 32, successively enters inspection volume 24, which is spanned by inspection units 40 to be explained in more detail. Thus, it is shown in FIG. 3 that the container 10 is first subjected to an optical inspection by an inspection unit 40 arranged above the transport device 30 in the correspondingly formed inspection volume 24. An inspection of a mouth formed in the neck area 14 is thereby possible, in particular with regard to ovality, and the interior of the container 10 at least in the neck area 14.

[0051] In a further inspection volume 24, spanned in particular by several inspection units 40, which are arranged at the side of the transport device 20 (not shown), the entire side wall surface 24 of the container 10 is preferably subjected to an optical inspection. The method used thereby depends on whether the container 10 is at least partially transparent or opaque, so that there can be variation between a transmitted light method and an incident light method.

[0052] In a further inspection volume 24, spanned by correspondingly designed inspection units 40, suitably positioned in relation to the area of the container 10 to be inspected, the threaded area 12 of the container 10 is inspected, in particular with regard to roll-on outside diameter, ovality, overall height, depth, width and/or inclination of surfaces. It is also possible to check whether there are contamination and defects in the threaded area.

[0053] FIG. 4 shows a top view of an area of the device 100 according to FIG. 3. Shown is the area of the device 100 that is set up to inspect the entire side wall surface 26 of the container 10. In the embodiment shown, four inspection units 40a, 40b, 40c, 40d are shown, each comprising a camera unit 20a, 20b, 20c, 20d, an illumination unit 34 or respectively 34a, 34b, 34c, 34d, and filter elements 36 or respectively 36a, 36b, 36c, 36d, which may be arranged on the camera unit 20 and/or on the illumination unit 34. These elements, grouped together in an assembly designated as inspection unit 40, can be mounted in a movable way on a guide mechanism, which is in the form of a rail system (not shown). The guide mechanism may have a drive mechanism by means of which the inspection units 40 and/or the included elements may be individually moved translationally and/or rotationally to allow alignment of the respective camera unit 20 and/or illumination unit 34 with respect to the inspection volume 24 and/or with respect to further inspection units 40.

[0054] As shown in FIG. 4, the inspection volume 24 is formed by four inspection units 40a, 40b, 40c, 40d, whereby in each case two inspection units 40a, 40c and 40b, 40d face each other, i.e. on opposite sides of the transport device 30. Thus, optical axes 42a, 42c and 42b, 42d of the respective camera units 20a, 20c and 20b, 20d lie substantially on one line. The total of four optical axes 42a, 42b, 42c, 42d intersect at a crossing point, or respectively crossing region, 44 within the inspection volume 24. However, it is also possible to provide an arrangement in which the individual optical axes 42a, 42b, 42c, 42d do not all meet in a single intersection point, but in a multiplicity of intersection points relatively close to one another. On each of the sides of the transport device 30, the optical axes 42a and 42b or respectively 42c and 42d of the inspection units 40a, 40b and 40c, 40d are at an angle to one another, preferably at an angle of about 90°. By means of this arrangement of the inspection units 40a, 40b, 40c, 40d, a container 10 located in the inspection volume 24 can be inspected in the transmitted light method as well as in the incident light method and in the dark field method. With the arrangement of the inspection units 40 side by side and parallel in transport direction 32, it is possible to record the entire side wall surface 26 of the container 10.

[0055] According to an embodiment of the invention, the camera unit 20 is configured as a line scan camera, whereby the length of a line sensor of the camera unit 20 is approximately adjustable to the length of the side wall surface 26 of the container 10. Line scan cameras have the advantage that they allow a very high image resolution in one imaging direction and at the same time a very high recording speed. To generate a high-resolution image of the entire side wall surface 26 of the container 10, the images taken by the camera units 20 are combined by a special image processing device.

[0056] In order to capture the most meaningful images possible of the container 10 under inspection, the device 100 includes illumination units 34, which may be, for example, static illumination means configured to optimally illuminate the entire inspection volume 24. In a preferred embodiment, each of the inspection units 40 includes an illumination unit 34 such that it is provided in an arrangement corresponding to a transmitted light configuration and an incident light configuration with respect to at least one of the camera units 20. In particular, each illumination unit 34 may be a conventional visible light source, an infrared light source, a UV source, a laser source or a combination thereof. Advantageously, the illumination unit 34 is adaptable to the specific optical testing to be performed on the container 10. Furthermore, the illumination unit 34, which is connectable to the camera units 20 of the inspection unit 40 directly or via a suitable means, can be moved along with the inspection unit 40 or can be moved individually in order to enable an optimal illumination of a container 10 to be imaged by the camera units 20. Further illumination means (not shown) can also be provided, which are each located essentially slightly laterally offset with respect to the axis between the camera units 20 and the container 10 to be tested and are used for the backlighting. Thus, when the camera unit 20a is switched on, the background illumination on the opposite side (i.e. between the container 10 and the camera unit 20c) can be used.

[0057] Thanks to these different lighting means, it is also possible to use a time multiplexing of different lighting types for one camera unit at a time. Thus, for example, a line with incident light and then a line with transmitted light can be recorded alternately and/or first a line with visible light, followed by a line with infrared illumination. A sequence of R-G-B recordings is also conceivable. In this way, multiple image types can be captured using a single camera unit.

[0058] FIG. 5 shows a schematic top view of an embodiment of the device 100 according to the invention. Shown is the device 100 for the inspection of containers 10, which are conveyed along the transport direction 32 by means of a transport device 30 and thereby pass through a multiplicity of areas of the device 100, in which inspection volumes 24 are spanned by inspection units 40. The device 100 includes a multiplicity of areas, with area 50 already shown in FIG. 3. An area 60 of the device 100 is provided to inspect the container 10 or its contour for so-called slugs. For this purpose, illumination unit 34 and camera unit 20 are arranged opposite each other, so that the container 10 to be inspected is at least partially located in between. Through optical testing with backlighting, starting from the illumination unit 34, the contour and the slugs of the container 10 to be tested can be clearly distinguished from each other. Furthermore, shown in FIG. 5 is an area 70, which is provided to inspect the entire side wall surface 26 of the container 10 for any areas of thinness of the material. For this purpose, for example, a so-called dark field method can be used, whereby camera unit 20 and illumination unit 34 are matched to each other accordingly. Accordingly, the camera unit 20 is positioned relative to the illumination unit 34 in such a way that the light deflected by defects is detectable by the camera unit 20.

[0059] An area 80 of the device 100 is set up to inspect the container 10 by means of infrared radiation, whereby an infrared camera unit and a matched IR illumination unit are provided. By means of infrared radiation or an IR inspection unit used, changes in the adsorption or emission behavior in the case of inhomogeneity in the material of the container 10 can be detected and possibly, based on this, conclusions drawn about the manufacturing process and the tooling used for this.

[0060] In an area of the device 100 designated by 90, it is indicated in FIG. 5 that the bottom area 18 of the container 10 can also be subjected to an optical inspection. For this purpose, the container 10 can be lifted off the conveyor belt 31 by suitable means, e.g. gripping means, so that the bottom area 18 is accessible for an optical inspection by the corresponding inspection unit 40.