METHOD AND DEVICE FOR TESTING PREFORMS

Abstract

A device and method tests preforms that are rotationally symmetrical with respect to an axis of rotation during their conveyance along a conveyance path. The device and method tests only a statistically relevant number of produced preforms, thus allowing substantial reduction in the constructive complexity required for aligning the preforms prior to being tested. A certain number of preforms that have not been correctly aligned are allowed to continue along the conveyance path without being tested.

Claims

1.-23. (canceled)

24. A method for testing preforms during their transport along a transport path by a transport device, each of the preforms being rotationally symmetrical with respect to an axis of rotation and having a mouth and a bottom end situated opposite the mouth, the transport device including a plurality of supporting profiles disposed parallel to one another and spaced apart from one another, the plurality of supporting profiles forming a transport surface and are movable in a transport direction from an inlet side to an outlet side of the transport device, wherein the method comprises the following steps: moving the supporting profiles at the same speed in the transport direction, depositing preforms on the supporting profiles on the inlet side of the transport device with any alignment of the axes of rotation and any orientation of the mouths of the preforms, aligning the axes of rotation of at least some of the preforms in the transport direction by introducing an angular momentum into the preforms, wherein each of the at least some of the preforms deposited on the supporting profile is a correctly aligned preform after the step of aligning, and wherein each of the correctly aligned preforms rests at a total of four bearing points on two adjacent supporting profiles, transporting the correctly aligned preforms in the direction of the outlet side along the transport path by static friction between two supporting profiles in each case and the four bearing points of the preforms, recording images of the preforms during transport in the direction of the outlet side, and processing the recorded images in a processing device.

25. The method as claimed in claim 24, wherein the bottom end of the each of the preforms has a smaller diameter than the mouth, and the angular momentum is introduced in such a way that a mouth-side supporting ring or a closure thread of the preform rotates about the bottom end of the preform.

26. The method as claimed in claim 24, wherein the transport device is a belt conveyor and the supporting profiles are embodied as supporting belts and move in the transport direction between two deflections in an upper strand of the belt conveyor.

27. The method as claimed in claim 24, wherein the parallel spacing of the supporting profiles is disposed such that the spacing is smaller than a smallest diameter of the hollow-cylindrical shell of each deposited preform.

28. The method as claimed in claim 24, wherein the angular momentum is introduced into the preforms by at least one of downhill-slope forces acting on the preforms on the transport surface inclined with respect to horizontal, a fluid flow from a nozzle, and collisions of the preforms with collision bodies.

29. The method as claimed in claim 28, wherein the angular momentum is introduced into the preforms by the collisions of the preforms with the collision bodies, each adjacent pair of supporting profiles forms a track, and the collision bodies are arranged along the tracks in such a way that the correctly aligned preforms are transported with a free track spacing along the transport path.

30. The method of claim 24, wherein the step of recording the images of the preforms is performed using at least one image recording device aligned with the transport surface.

31. The method as claimed in claim 30, wherein the at least one image recording device is arranged in such a way that images of shell surfaces of the correctly aligned preforms are recorded.

32. The method as claimed in claim 31, the step of recording uses at least one further image recording device arranged in such a way that images of the correspondingly oriented mouths of the correctly aligned preforms are recorded.

33. The method as claimed in claim 24, further comprising illuminating the preforms by at least one of an illumination device on the opposite side of the supporting profiles from the transport surface and an illumination device above the transport surface.

34. The method as claimed in any of claim 24, further comprising: determining the correctly aligned preforms by testing on the basis of the recorded images of the preforms to determine: whether the preforms are correctly aligned in the transport direction; or whether the preforms are correctly aligned in the transport direction and their mouths are oriented in a corresponding manner, and testing, using the processing device, object features of the correctly aligned preforms.

35. The method as claimed in claim 34, further comprising separating out at least one of preforms that are not correctly aligned preforms and preforms that have been identified as defective during the testing of the object features.

36. A device for testing preforms during transport along a transport path, said preforms being rotationally symmetrical about an axis of rotation, the device comprising: a transport device configured to transport the preforms along a transport path, the transport device having a plurality of supporting profiles parallel to one another and spaced apart from one another, the plurality of supporting profiles forming a transport surface and being movable at a same speed from an inlet side to an outlet side of the transport device, a feed arranged on the inlet side of the transport device configured to deposit the preforms on the supporting profiles with any alignment of the axes of rotation and any orientation of the mouths, an alignment region of the transport path configured to align the axes of rotation of at least some of the preforms in the transport direction by introducing an angular momentum into the preforms, wherein each of the at least some of the preforms deposited on the supporting profile is a correctly aligned preform after the step of aligning, and wherein each of the correctly aligned preforms rests at a total of four bearing points on two adjacent supporting profiles, a transport region of the transport path configured to transport the correctly aligned preforms in the direction of the outlet side by static friction between two supporting profiles in each case and the four bearing points of the preforms, at least one image recording device for recording images of the preforms during transport in the direction of the outlet side, and a processing device for processing the recorded images.

37. The device as claimed in claim 36, wherein the transport device is a belt conveyor having a plurality of supporting belts that circulate between two deflections in an upper strand and a lower strand, wherein the sections of the supporting belts that run in the upper strand of the belt conveyor form the supporting profiles.

38. The device as claimed in claim 37, further comprising sliding profiles supporting the supporting belts arranged in the upper strand of the belt conveyor at least over a part of the transport path.

39. The device as claimed in claim 36, wherein the parallel spacing of the supporting profiles defines a spacing that is smaller than a smallest diameter of a hollow-cylindrical shell of each preform to be transported.

40. The device as claimed in claim 36, wherein the transport surface is inclined with respect to the horizontal, at least in the alignment region, in such a way that the angular momentum is introduced into the preforms by downhill-slope forces acting on the preforms.

41. The device as claimed in claim 36, further comprising at least one nozzle connected to a turbomachine, the at least one nozzle being arranged above the transport surface and producing a fluid flow aligned with the alignment region of the transport path in such a way that an angular momentum is introduced into the preforms.

42. The device as claimed in claim 41, wherein the at least one nozzle is an air blade arranged transversely with respect to the transport direction.

43. The device as claimed in claim 36, further comprising collision bodies acting above the transport surface and arranged in such a way that the angular momentum is introduced into the preform when a preform strikes one or more of the collision bodies.

44. The device as claimed in claim 43, wherein each pair of adjacent supporting profiles arranged spaced apart from one another forms a track with a gap located between them, and collision bodies act only above each second track.

45. The device as claimed in claim 36, wherein the at least one image recording device is aligned with the transport surface.

46. The device as claimed in claim 36, further comprising at least one of an illumination device arranged on a side of the supporting profiles opposite the transport surface and an illumination device arranged above the transport surface.

Description

[0044] The invention is explained in greater detail below with reference to exemplary embodiments. In the drawings:

[0045] FIGS. 1a, b show a first exemplary embodiment of a device for testing preforms with a transport device whose transport plane is inclined with respect to the horizontal, in a side view and in a perspective view,

[0046] FIGS. 2a, b show a second exemplary embodiment of a device for testing preforms with a transport device having a horizontal transport plane, in a side view and in a perspective view, and

[0047] FIGS. 3a, b show a third exemplary embodiment of a device for testing preforms with a transport device having a horizontal transport plane, in a side view and in a perspective view.

[0048] FIGS. 1a), b)-3a), b) show all the devices (1) for testing preforms (2) which are rotationally symmetrical about an axis of rotation (3). In the region of their mouth (4), the preforms (2) have a supporting ring (5), which has a larger diameter than the bottom end (6) of the hollow-cylindrical shell (7) (compare details A in FIG. 3).

[0049] Each device (1) comprises, as an essential component, a transport device (8) which transports the preforms (2) along a transport path (11) from an inlet side (9) to an outlet side (10). In the illustrated exemplary embodiment, the transport device (8) is designed as a belt conveyor (12) having a multiplicity of supporting belts (13), which circulate between a deflection (14.1) on the inlet side (9) and a deflection (14.2) on the outlet side (10) in an upper and lower strand (15.1, 15.2). The belt conveyor (12) is driven by means of a head drive (not illustrated) of the deflection (14.2) via a shaft (16). Those sections of the supporting belts (13) which run in the upper strand (15.1) form supporting profiles (17) with a round cross section. The supporting profiles (17) form a transport surface (19) for the preforms (2) to be transported from the inlet side (9) to the outlet side (10).

[0050] A feed (not illustrated), by means of which the preforms (2) are deposited on the transport surface (19) with any alignment of the axes of rotation (3) and any orientation of the mouth (4), is arranged on the inlet side (9) of the transport device (8). In an alignment region (11.1) of the transport path (11), the preforms (2) are aligned in the transport direction (18), i.e. parallel to the supporting belts (13) of the belt conveyor (12), by introducing an angular momentum. According to the invention, not all of the preforms (2) deposited are correctly aligned, but only a statistically relevant quantity. The correctly aligned preforms (2) are illustrated in the transport region (11.2) in FIG. 1 b). These correctly aligned preforms (2) rest at a total of four bearing points on two adjacent supporting belts (13). These are two bearing points on the supporting ring (5) and two further bearing points on the bottom end (6). On account of the mass distribution and geometry, the mouth (4) of the majority of the correctly aligned preforms (2) points in the direction of the inlet side (9).

[0051] The angular momentum in the exemplary embodiment according to FIG. 1 is brought about, on the one hand, by downhill-slope forces acting on the preforms (2) and, on the other hand, by collision bodies (21) acting above the transport surface (19). The downhill-slope forces act on the preforms (2) because the transport surface (19) is inclined by a positive slope angle α of approximately 30 degrees with respect to the horizontal. As long as they have not yet been aligned in the transport direction (18), the preforms have the tendency to roll in the direction of the inlet side (9) on the transport surface (19), counter to the transport direction (18), as a result of the downhill-slope forces. Owing to the different diameters of the supporting ring (5) and of the bottom end (6) of the preform (2), the supporting ring (5) of the preform (2) rotates about the bottom end (6) of the preform (2) in the plane of the transport surface (19) and, in the process, is aligned in the transport direction (18). In addition, the preforms (2) which have not been correctly aligned after deposition collide with the collision bodies (21) arranged in the alignment region (11.1) directly downstream of the feed. An angular momentum is thereby likewise introduced into the impinging preforms (2).

[0052] However, the collision bodies (21) not only assist the alignment of the preforms (2) but also distribute them over the entire width of the belt conveyor (12). In some cases, the preforms (2) are also not aligned completely when they strike the collision bodies (21), but are instead raised and transported onward in the transport direction (18) by the supporting belts (13). In order to avoid a jam in front of the collision bodies (21), the latter are preferably designed as sorting wedges (22), the front flank of which encloses an acute angle with the transport surface (19). As a result, individual preforms (2) can be raised by means of the sorting wedges. The angle of the rear flank of the sorting wedges with respect to the transport surface (19) is determined in such a way that preforms which have not been correctly aligned and have been raised by means of the sorting wedge can, where applicable, roll back in the direction of the inlet side (9), counter to the transport direction (18).

[0053] In the illustrated exemplary embodiment, eleven sorting wedges (22) are provided in the alignment region (11.1), which sorting wedges are arranged in three rows (23.1, 23.2, 23.3) transversely to the transport direction (18), wherein the sorting wedges (22) are arranged in adjacent rows (23.1, 23.2, 23.3) in a manner offset relative to one another transversely to the transport direction (18), as is illustrated, in particular, by detail A in FIG. 1.

[0054] Two supporting belts (13) circulating at a distance from one another in each case form one track (24), as can be seen from detail A in FIG. 1. The sorting wedges (22) are not arranged in all the tracks (24) but only in every second track (24). This will ensure that the preforms (2) aligned by the sorting wedges (22) are transported at a spacing of one track (24) with respect to one another and, when the images of the preforms (2) are recorded in the transport region (11.2), masking by directly adjacent, aligned preforms (2) will be avoided.

[0055] Detail C of FIG. 1 shows that sliding profiles (25) for supporting the supporting belts (13) are arranged below the supporting belts (13) in the upper strand (15.1) over part of the transport path (11). The sliding profiles (25) guide, stabilize and support the supporting belts (13) along the entire alignment region (11.1) and the outlet end of the transport region (11.2) of the transport path (11).

[0056] In the transport region (11.2) of the transport path (11), images of the preforms (2) are recorded during transport in the direction of the outlet side (10).

[0057] In order to test the shell (7) of the preforms (2) with correct alignment, two image recording devices (26.1) are arranged above the transport surface (19), the axes of the viewing direction (27.1) of which are perpendicular to the transport surface (19). To record the mouth (4) of the preforms (2), three further image recording devices (26.2) are directed at the transport surface (19). The axes of the viewing direction (27.2) of the image recording devices (26.2) are at an acute angle to the transport surface (19) (cf. FIG. 1a). The recording devices (26.1, 26.2) are each arranged adjacent to one another transversely to the transport direction (18).

[0058] To illuminate the preforms (2) during the recording of the images, an illumination device (28) in the form of a transmitted-light lamp is arranged between the upper and lower strands (15.1, 15.2) of the belt conveyor (12). The transmitted-light lamp is designed as a planar luminous field which extends over the entire width of the transport surface (19) and has a diffuse emission characteristic.

[0059] From FIG. 1 b), it can be seen that the supporting belts (13) run without supporting the sliding profiles (25) in the region of the illumination device (28). Since the supporting belts (13) consist of a transparent material, the belt conveyor (12) used according to the invention allows full-surface illumination of the preforms (2) from their underside.

[0060] Furthermore, during the recordings, the preforms (2) are illuminated by means of a further planar illumination device (29) above the transport surface (19), which is designed as a planar incident-light lamp and extends over the entire width of the transport surface (19). In order to reduce reflections on the surface of the preforms (2), the surface of the incident-light lamp encloses an angle of approximately 45 degrees with the axis of the viewing direction (27.1) of the image recording device (26.1), as can be seen, in particular, from the side view according to FIG. 1a).

[0061] The image recording devices (26.1, 26.2) record the images of the passing preforms (2) at a fixed recording frequency. The recorded images are then processed in a personal computer (not illustrated). First of all, the alignment of the preforms (2) is tested. If the alignment lies outside a tolerance range or if accumulations of a plurality of preforms (2) are detected, these preforms (2) are not taken into account in the further evaluation of the image. Subsequently, the preforms recognized as correctly aligned in the image are tested for the object features of the shell (7) which are to be tested, such as color, for example. For the evaluation of object features in the region of the mouth (4), the images of the image recording device (26.2) are evaluated in the same way by the processing unit. First of all, the orientation of the mouth (4) is tested in a first testing step. If the mouth (4) is pointing in the direction of the inlet side (9), it is correctly oriented in the illustrated exemplary embodiment and, in a next step, is tested for the object feature to be tested, for example the dimensions of the mouth (4).

[0062] The embodiment of the device (1) according to FIGS. 2 a, b) differs from the device according to FIGS. 1 a), b) in that an angular momentum is introduced into the preforms (2) not by downhill-slope forces but exclusively by the collision bodies (21), which are arranged in the same way as in the exemplary embodiment according to FIGS. 1 a), b) and additionally by a fluid flow (30), in particular an air flow (cf. details D in FIG. 2 a)). To generate the fluid flow (30), an air blade (31) is arranged transversely to the transport direction (18) above the transport surface (19) and is connected to a fan (not illustrated). The laminar fluid flow (30) emerging from the air blade (31) over the entire width of the transport surface (19) acts on the preforms (2) in the opposite direction to the transport direction (18), as a result of which, owing to the geometry and mass distribution of the preforms (2), an angular momentum is introduced into the preforms, insofar as they have not already been aligned. In the exemplary embodiment according to FIG. 2, the belt conveyor (12) is not inclined with respect to the horizontal, but it could be inclined in the same way as in the exemplary embodiment according to FIG. 1 if downhill-slope forces are additionally intended to be effective for generating the angular momentum.

[0063] Finally, FIG. 3 shows an exemplary embodiment of the device according to the invention in which the transport device (8) is not inclined with respect to the horizontal and an angular momentum is introduced into the preforms (2) exclusively via the air blade (31). The fluid flow (30) acting counter to the transport direction (18) over the entire width of the transport surface (19) imparts rotation to the preforms (2) without hindrance from collision bodies (21), the supporting ring (5) rotating in the horizontal, flat transport surface (19) about the bottom end (6) of the preform, which is of smaller diameter.

[0064] In the exemplary embodiment according to FIG. 3, the belt conveyor (12) is not inclined with respect to the horizontal, but it could be inclined in the same way as in the exemplary embodiment according to FIG. 1 if downhill-slope forces are additionally intended to be effective for generating the angular momentum.

TABLE-US-00001 No. Designation 1. device 2. preform 3. axis of rotation 4. mouth 5. supporting ring 6. bottom end 7. shell 8. transport device 9. inlet side 10. outlet side 11. transport path 11.1 alignment region 11.2 transport region 12. belt conveyor 13. supporting belt 14.1 deflection 14.2 deflection 15.1 upper strand 15.2 lower strand 16. shaft 17. supporting profiles 18. transport direction 19. transport surface 21. collision body 22. sorting wedge 23.1 row 23.2 row 23.3 row 24. track 25. sliding profile 26.1 image recording device 26.2 image recording device 27.1 axis of viewing direction 27.2 axis of viewing direction 28. illumination device 29. illumination device 30. fluid flow 31. air blade