Process and Apparatus for the Testing of Packs

The invention relates to a process for the testing of packs for a plurality of articles, especially biscuits, the articles being arranged in ordered groups (stacks) and being surrounded by a deformable wrapping. The invention also relates to an apparatus for the testing of articles or groups of these.

In the packaging of articles, one problem is that the manufacturer has to ensure that the pack content is correct. If, for example, the pack content consists of a specific number of identical individual articles, such as biscuits, there must be neither one short nor one too many. Furthermore, none of the biscuits may be broken or have been put askew during packaging. The check conducted hitherto on the still open pack often cannot give any information on this because faults of this type can occur when the soft pack is being closed.

The object on which the invention is based is to carry out the testing of the content of packs quickly, accurately and at a low outlay.

To achieve the object, the process according to the invention is characterized in that the number of articles and/or their correct arrangement within the wrapping are tested by feelers movable against the latter, this at the same time undergoing deformation, and defective packs detected in this way are separated out.

Thus, the articles or groups of these are tested inside the pack which consists of a wrapping deformable at least in the part regions important for testing. For this, a test member, in particular a feeler assigned to each group, penetrates deeper into the pack when articles within a group are missing, the wrapping thereby experiencing correspondingly greater deformation. When articles within a group are askew and the dimensions of the latter are enlarged as a result, the test member, that is to say the feeler, can also undergo a shift in another direction.

During the testing of a pack, the relative position of the feelers is monitored, especially by optoelectrical members. Deviations of the feeler from a middle or normal position trigger an error signal, the result of which is that the pack is separated out.

According to a further feature of the invention, the packs are tested during their transport. The test members, in particular mechanical feelers, are conveyed in synchronism with the particular pack to be tested. If the stacks of articles (biscuits) are arranged transversely relative to the conveying direction, feelers are appropriately assigned to each stack on both sides of the pack. Testing is carried out in the region of a limited test zone of a conveyor for the packs.

The feelers are preferably arranged on the conveyor for the packs themselves, especially on lateral toothed belts. The feelers or a housing (guide) of these are appropriately connected firmly to the associated toothed belt, especially formed on this as an integral work-piece. The toothed belts are therefore produced with groups of feelers or housings (guides) for these feelers which are arranged at a distance from one another.

Any defective packs detected are eliminated in the region of the conveying zone, especially by means of a downward-pointing ejection shaft arranged in the region of the conveyor for the packs. During the transport of intact packs, this ejection shaft is covered at least partially. When a defective pack is identified, the ejection shaft is opened, so that the defective pack conveyed passes automatically into the ejection shaft.

Further features of the invention relate to the design of the conveyor for the packs, and, above all, to the feeler members.

An exemplary embodiment of the invention is explained in greater detail below with reference to the drawings.

In these:

FIG. 1 shows an apparatus for the testing of the content of packs in a diagrammatic plan-view representation,

FIG. 2 shows a side view of FIG. 1,

FIG. 3 shows a side view of an end portion of a conveyor on an enlarged scale,

FIG. 4 shows a vertical section along the plane IV--IV in FIG. 3 on a further-enlarged scale,

FIG. 5 shows a vertical section along the plane V--V in FIG. 2, likewise on an enlarged scale.

The apparatus described below serves for the testing of the content of packs 10 which, in the example shown here, each contain three stacks 11, 12, 13 of (round) biscuits 14. The soft packs have a wrapping 15 which consists of transparent film and which is equipped with a gripping tab 16 on one (end) face as a result of welding together.

The packs 10 are pushed over a sliding track 18 by strip-shaped take-up crossmembers 17. The take-up crossmembers 17 are fastened to toothed belts 19, 20 which rotate on both sides of the sliding track 18.

Feelers 21 are fastened to the toothed belts 19, 20, specifically one feeler 21 for each end face of a stack 11, 12, or 13. The feelers 21 have a feeler plunger 22 which is connected to an engagement means 24 via a ram 23. The feeler plunger 22 rests in a guide 25 which is formed on the toothed belt 19, 20. The guide 25, at its end facing away from the feeler plunger 22, is provided with a bore through which the ram 23 passes. Inserted between the inner end of the guide 25 and the rear end of the feeler plunger 22 is a compression spring 26 which loads the feeler plunger 22 in the direction of the pack 10.

The feelers 21 are designed or connected to the toothed belts 19, 20 in a special way. For this purpose, the cylindrical feeler housings designated as the guide 25 and intended for receiving the feeler plunger 22 and the ram 23 are formed on the toothed belts 19, 20 or are designed as a joint integral work-piece with these. To that extent, therefore, the feelers or their guides 25 are produced together with the toothed belts 19, 20.

The engagement means 24 of the feeler 21 is made disk-shaped and has conical end faces 27, 28 which are connected to one another via a cylindrical portion 29.

Parallel to the sliding track 18 or to the toothed belts 19, 20, there are on both sides rails 30, 31, the lower edge 31 of which is shaped, on the outside, so as to match the inner end face 27 of the engagement means 24. At the same time, the rails 30, 31 are arranged in such a way that the engagement means 24 rest by means of their inner end face 27 against the bevelled lower edge 32 of the rails 30, 31 and can slide along on this when the toothed belts 19, 20 move in the direction of the arrow.

The rails 30, 31 are fastened parallel to the toothed belts 19, 20 over the entire conveying zone, with the exception of a short portion. In front of this short portion, the rails 30, 31 converge in the direction of the toothed belts 19, 20 and end just before this portion. After this portion, the rails 30, 31 diverge again.

In the region where the rails 30, 31 are not provided or are at their shortest distance from the toothed belts 19, 20, a reflection light barrier 33, 34 is attached on each side. The light barriers 33, 34 are directed towards the path of movement of the engagement means 24 perpendicularly relative to the conveying plane, in such a way that, when there is an intact stack, the cylindrical portion 29 of the engagement means 24 moves along directly under the associated light barrier 33, 34.

When, during operation, a pack 10 is pushed over the sliding track 18 via the toothed belts 19, 20 by means of the take-up crossmember 17, the engagement means 24 first rest by means of their inner end faces 27 against the lower edges 32 of the rails 30, so that the plungers 22 are pulled back from the pack 10 and the springs 26 are compressed. When the engagement means 24 enter the region in which the rails 30, 31 approach one another, the plungers 22 run onto the end faces of the packs 10 as a result of the force of the springs 26. If the pack content, namely the stack, has the prescribed height, as shown in FIG. 1 at the left-hand end of the leading stack 13 (as seen in the conveying direction) and at the left-hand ends of the stacks 11, 12, the cylindrical portion 29 of the engagement means 24 runs past exactly underneath the reflection light barriers 33 and 34, so that these transmit a maximum reflection signal. However, if a biscuit was broken when the pack was being closed, so that the stack 12 is higher than prescribed, the light emitted by the reflection light barriers 33, 34 does not arrive at the cylindrical portion 29 but at the conical portion 27 and is therefore not reflected back to the light barrier 33, 34. In the same way, if there is an incomplete stack 11, the light does not arrive at the cylindrical portion 29, but as the outer end face 28 and is likewise not reflected. Thus, it is possible to make an exact distinction between the positions and consequently detect defective pack contents accurately. An essential factor here is also the conical shape of the end faces 27, 28 with the cylindrical portion located between them. In particular, as a result of these differences in shape, it is possible to make an especially sharp distinction between the correct position and a fault-indicating position of the engagement means 24 or of the feeler plunger 22. Only when the feeler plunger 22 is pressed outwards so far that the light of the reflection light barrier 33, 34 strikes the cylindrical connecting piece between the engagement means 24 and the ram 23 can larger error signals occur. The working range of the arrangement can thus be determined by the slope of the end faces 27, 28.

The light barriers 23, 24 are connected to a logical evaluation unit (not shown here) which determines whether a pack is to be classed as defective or not. If a pack 10 is classed as defective, it has to be separated out.

For separating out defective packs, a cut-out 35 is made in the sliding track 18 shortly after the region in which the feelers 21 sense the packs 10. The cut-out 35 extends over the entire width of the sliding track 18 and over a length which is somewhat greater than the width of a pack 10. The cut-out 35 can be partially covered by two covering blades 36, 37, the faces of the covering blades 36, 37 being essentially flush with the surface of the sliding track 18. The covering blades 36, 37 are fastened to guide rods 38, 39 which form piston rods of pneumatic cylinders or the like (not shown). The covering blades 36, 37 can be drawn out via these pneumatic cylinders, until the cut-out 35 is opened completely, or can be moved into the cutout 35, until a delivered pack 10 can slide across the cut-out 35 on the covering blades 36, 37.

An ejection shaft 40 is arranged underneath the cut-out 35. The ejection shaft 40 has a front wall 41 and a rear wall 42 which extend parallel to one another and which are inclined in the conveying direction.

Arranged above the cut-out 35 is an ejector punch 43, the punch plate 44 of which has a face parallel to the sliding track 18 and is connected to a ram 45 attached to the punch plate 44 at an inclination. This inclination corresponds to the inclination of the ejection shaft 40. The ram 45 is connected for actuation purposes to a pneumatic cylinder (or the like) (not shown).

When it has been found by means of the light barriers 33, 34 that a pack is defective, the covering blades 36, 37 are drawn back via the control (not shown), and when the defective pack 10 arrives the ejector punch 43 is moved down so that the defective pack 10 is conveyed downwards into the ejection shaft 40. The special arrangement of the ejector punch 43 and of the ejection shaft 40 in respect of the direction of ejection guarantees that the packs 10 to be ejected can execute only an insignificant relative movement in relation to the punch plate 44, if at all, and can therefore be ejected in a particularly effective and faultless way. The control device which receives the signals from the light barriers 33, 34 and which then activates the actuation means for the covering blades 36, 37 and the ejector punch 43 is synchronized with the drive for the toothed belts 19, 20, so that ejection at exactly the right time is possible.

Those packs 10 recognized to be perfect are transferred to a conveying chute 47 in the region of deflecting rollers 46 deflecting the toothed belts 19, 20 and then enter a further section (not shown here) of the packaging apparatus.

The rails 30, 31 are brought together again in the region of the deflecting roller 46, so that the springs 26 can push the feeler plungers 22 inwards again and the engagement means 24 of the feelers 21 can run freely during the advance of the latter. Correspondingly, at the second deflecting roller (not shown here), the engagement means 24 are again brought up to appropriately diverging portions of the rails 30, 31 and then pull the plungers 22 back into the guides 25 once more, so that the packs 10 can be deposited freely.

It also emerges from the drawings that, at the same time, the sliding track 18 is equipped on its outer portion with belt guides 48 for the toothed belts 49. Furthermore, the sliding track 18, at its edges, has guide fences 49 for guiding the packs 10, so that these cannot tilt or come up to the retracted feeler plungers 22. Moreover, the guide fences 49 ensure that, during the testing operation carried out by the feelers 21, the packs 10 assume a specific position in relation to these feelers.