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(11) | EP 0 574 346 A2 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | A destacker for bundles of printed papers, and an application thereof |
| (57) The invention is based on the recognition that by a systematic data processing of
returned newspapers, which carry a bar code identifying the daily edition number and/or
the sales district, it will be possible to plan the production and the distribution
for minimizing the returnings. However, in practice this will require the use of a
destacker which can operate with a very high capacity and handle papers of widely
different thicknesses. Previous destackers have had to be adjusted to a specific paper
thickness when a high operation speed is required, e.g. 3-6 copies per second. The
invention provides for a destacker which can operate at high speed with both thick
and thin copies, based on the clamping parts (28,30) gripping the single copies (22)
and drawing these out from the bundle with high speed are held together by the use
of a suitably high spring force with a pronounced soft spring characteristic, preferably
by the use of compressed air cylinders (52). |
[0001] The present invention relates to a destacking apparatus, primarily for successive removal of printed copies such as returned newspapers from bundles of such copies, and of the type specified in the introductory clause of claim 1.
[0002] It has already been proposed, confer DE-B-25 31 486 and US-A-4,042,113, that bundles of returned printed copies can be laid on a destacker, which will successively draw out the lowermost copy and feed the copies to a conveyor, on which the copies are moved past a reading station, in which a marking such as a bar code on the copies is read automatically; the readings are fed to a computer for data processing, e.g for controlling a sorter device or for counting of different types of returned copies, the computer initially being informed of the identity of the supplier of the bundle.
[0003] In connection with the invention special attention is paid to bundles of return newspapers, as it has been recognized that more detailed bar code informations, which indicate the publication district and time for newspapers with more daily editions, can be very useful for the planning of the publication activities, when the handling of the return bundles may show the number of return copies coming in from the different districts, related to the different daily editions.
[0004] It is no problem to let the computer sum up these informations, when they can be read through the bar codes, but a big problem occurs in that just return newspapers appear in such large numbers that the required machinery, in practice, should be able to operate at very high speed for catching up with the deliveries of the return bundles.
[0005] A closely related problem is that the return bundles of newspapers will very often include copies of different thicknesses and that this practice will be diffult to change. For the known destackers the situation is that some may well handle copies with different thicknesses, but then with low speed only, while others may operate at high speed, but only when adjusted to a specific approximate thickness of the copies.
[0006] For fast working destackers it is usual that the destacking is effected by a bending down of the folding edge area of the lowermost copy in the bundle and thereby a bringing down of the folded edge to an engagement area between a pair of rotating rollers, which will then draw out the copy from the bundle for delivery of the copy to a conveyor belt or to other receiving and conveying means. Hereby the drawn out copy will be accelerated from stillstand to a quite high velocity almost momentarily, and if this is to take place in a reasonably safe manner it will be required that the gripping rolles are adjusted to a mutual spacing which will rather accurately correspond to the thickness of the copies.
[0007] One of the rollers may be influenced by strong spring means towards the other roller, and for adjustment to an increased copy thickness an abutment stop for the spring loaded roller may be adjusted away from the opposed roller, compulsorily bringing along the spring loaded roller. If or when, by any such adjustment, an overthick copy arrives for handling, this copy may well be handled, in as far as it will only cause the spring loaded roller to be pressed away from the abutment stop, against the action of the spring means. The printed copy itself will hardly be harmed by the roller pressure as hereby considerably increased, and at low operational speeds it would be perfectly possible to accept the handling of of overthick printed copies. After the passage of the copy the spring loaded roller may then calmly return into its stop position, ready for the handling of the following copy.
[0008] However, this picture will be radically changed when, as here considered, it is required to work with a high speed, typically with an extraction of 3-6 copies per second. The spring loaded roller will be influenced blowwise by the reception of each new copy of increased thickness, and the abutment stop will be affected correspondingly impact-like by the sudden return of the roller uopn the passage of the printed copy. A single overthick copy now and then could well be accepted, if the destacker is adjusted to a normal copy thickness, but it will be a problem, then, that underthick copies may just as well appear, which will give rise to another operative problem, viz. that the destacking is stopped, because such a copy cannot be gripped and drawn out. The normal adjustment, therefore, should be adapted to the expected 'most underthick' copies, but then the said return impacts will occur already by the handling of the normal copies and in a still worse manner when the overthick copies arrive. It is a qualified guess that a conventionally dimensioned destacker would break down in less than one hour under such conditions. There is the additional problem that when the spring loaded roller is thrown back by the occurrance of an overthick copy, this roller will exhibit a certain inertia, which, despite the counter pressure by the springs, may well result in a brief suspension of the driving engagement between the rollers and the copy, whereby the gripping of the copy can be deferred slightly; this may well be sufficient to cause disturbance of the destacking.
[0009] In connection with the invention it has been realised that in fact it is possible to solve these problems already by a relatively modest modifika- tion of a conventional destacker. It has been found that all what is required is a modification of the spring system of the spring loaded roller. According to the invention the desired result is achievable by the use of an air pressure supported return movement of the roller, although also other detailed solutions will be possible.
[0010] When the movable roller is held towards the stationary roller by the action of a piston in one or more compressed air cylinders, the roller will behave very different from its behaviour when influenced by a short mechanical spring. A modest damping of the movements will be effected, sufficient to make the discussed impacts and shakings practically disappear, even at high operation speeds, and the contact pressure will be substantially the same, no matter the thickness of the successive copies. When the roller is forced back the said inertia will of course still exist, but because of the high speed of the movement the air cylinder or cylinders will be subjected to a certain dynamical pressure build-up, which will disappear very soon, but yet be sufficient to prevent the roller from leaving its engagement with the gripped copy, such that the destacking can proceed in a safe and regular manner.
[0011] It has been found, surprisingly, that it is hereby possible to handle copies within a thickness range that is fully sufficient for the purpose in question, and that it is perfectly possible to adjust the destacker permanently to the thinnest possible copy, i.e. only a few or even a single layer of paper, such that in general there will be no need whatsoever to carry out operative adjustments. It is still preferable to make use of the said abutment stop for preventing the movable roller from directly hitting the stationary roller by its return movement.
[0012] It should be mentioned that in the return bundles there may well occur current newspapers with different thicknesses, already if the said daily editions are not equally thick. Another possibility is that the folded newspapers are often provided with inserts, which, when correctly placed, will have an edge located in the folding edge of the paper, whereby the thickness of the insert will be included in the total thickness of the folding edge area, while this will not be the case, if the insert has been displaced slightly from the folding edge. Thus, if a destacker has been adjusted to the full thickness, problems may arise with newspapers from one and the same edition, because the thinner folding edge area of the papers with displaced inserts cannot be gripped between the rollers. In connection with the invention, however, it is widely without importance how the thickness of the copies might vary, as they will be gripped anyway, provided they are correctly bundled.
[0013] In the following the invention is described in more detail with reference to the drawing, in which:
Fig. 1 is a schematic top view of a return bundle processing system,
Fig. 2 is a schematic side view of a destacker therein,
Fig. 3 is a corresponding side view of a modified destacker, and
Fig. 4 is a top view thereof.
[0014] In Fig. 1 is shown two destackers 2, which can receive bundles of return newspapers and transfer these, one by one, to respective conveyor belts 4, at which there is placed a copy counter 6 and a bar code reader 8. These units are connected to registration units 10, which in turn are connected to a common computer 12. Moreover, each of the units 2,10 is associated with a hand-held scanner 14 that is used for reading of the suppliers of the single bundles, it being prescribed that the bundles carry such a marking The conveyors 4 lead to a common delivery conveyor 16. The computer 12 is connected to a printer, which for each bundle may provide a transcription of the contents of different types of newspapers in the bundle.
[0015] As mentioned, it is hereby essential that the applied destackers can work with high speed and with paper units of different thicknesses. In Fig. 2 is schematicaaly shown a typical, conventional destacker having a carrier plate 20 for a laid-on pile 22 of newspapers and a front wall 24, against which is placed that side of the paper pile, by which the folded edges of the bundeled papers occur. The bottom or carrier plate 20 does not reach forwardly so far as to the front plate 24, and underneath the associated free space there is arranged a system of movable suction cups 26, which are guidable for gripping and and bending down the front end of the lowermost copy in the bundle, this being indicated in dotted lines.
[0016] A number of these suction cups is mounted in a line, and between them are mounted pairs of cooperating receiver rollers 28,30, of which the rollers 28 are motor driven through a shaft 32. These rollers have a recess 34, which can receive the bent down front end of the lowermost copy 22, whereafter an end wall 36 of the recess will force this front end down into engagement between the rollers 28 and 30, whereafter the copy will be drawn down between these rollers for delivery to a conveyor belt 38, i.e. during retraction from the carrier plate 20, while the overlying copy is held back by the front wall 24 of the destacker.
[0017] The rollers 30 or a long roller equivalent therewith are mounted on carrier arms 40, which at their lower ends are pivotal about fixed pivot pins 42, above which they are connected with spring means serving to press these rollers forwardly towards the rollers 28 and with an adjustable stop abutment 44, which limits the associated forward pivoting of the arms 40. The abutments 44 may be arranged on rearwardly projecting rods 46 passing through respective holes in fixed holding plates 48, behind which the screw threaded ends of the rods 46 are provided with adjustment nuts 50.
[0018] As far as the prior art is concerned it is important, when the machine is wanted to operate at high speed, to adjust the rollers 30, by means of the nuts 50, into a specific distance from the periphery of the rollers 28, corresponding rather accurately to an expected uniform thickness of the copies 22, but in connection with the invention this is changed such that this adjustment should correspond to the thickness of a single or just a few layers of paper, and for that sake the adjustable abutment 44 can be substituted by a fixed stop.
[0019] According to the invention the said forwardly biasing spring means preferably comprise one or more stationary compressed air cylinders 52, the piston rod or rods 54 of which are pivotally connected with the arm 40, while at their opposite ends the cylinders 52 are connected with a source of compressed air through a hose 58. As already mentioned, this will imply that the rollers 30 even at very high speed of operation will yield in a suitable manner in case of any overthick copies 22 arriving at the roller pairs 28,30.
[0020] It is important that by the associated impact-like reciprocating movements of the arms 40 there is no direct mechanical connection between the rollers 30 and the fixed machine parts, as this connection is pneumatical, whereby the impact effects are considerably attenuated. The spring action will not be a pure, real springing, as the effect will be a mixture of a constant, position independent pressure on the arms 40 and a resilient pressure caused by a dynamic compression of the air, which, when pressurized by the arm 40 being thrown to the right, cannot immediately return to the source of compressed air, because in that connection there will be a certain flow attenuation, e.g. given already by relatively thin hose connections between the source and the cylinders 52. Correspondingly, when the arm 40, by the action of the static air pressure, is abruptly swung to the left by the passage of the rear end of the drawn out copy, the pivoting of the arm towards and against the stop 42 will take place so rapidly that a certain dynamic pressure drop will occur in the cylinder, whereby the stop 44 will be hit with a moderate impact force. It could even be possible to place an impact damping material pad between the stop 44 and the arm 40.
[0021] According to the invention it is a possibility that a sufficient spring action can be obtained otherwise for ensuring that the pressure rollers 30 or corresponding pressure or gripping members may rapidly adapt themselves to different copy thicknesses, when only the resulting spring or counter pressure effect corresponds to what has been achieved so far described. Thus, it will surely be possible to use purely mechanical spring means, when these in an untraditional manner exhibit a characteristic adapted according to the desired effect as described, e.g. quite long screw springs which may maintain a practically constant pressure against a moved part, irrespectively of the actual movement, and which will not transfer impacts to a spring backing by occurring sudden movemts of the moved part.
[0022] According to the invention the basic condition is that the gap between the substantially stationary rollers 28 and 30 should be dynamically adjustable for accomodating the thickness of the single copies 22, but this is a special condition for the system shown in Fig. 2. There may well be other systems, in which, for example, it will be decisive that a gripping means comprising a fixed and a movable gripping jaw can rapidly grip a copy, and here it will correspondingly be a condition that the movable jaw should be arranged so as to be movable from a widely open position to a clamping position very near to the fixed jaw in a resilient manner, such that papers of different thicknesses can be safely gripped. When this is to take place really fast there will normally be big problems, unless the jaw is adjusted to grip copies of one specific thickness, but based on the principle of the invention the jaw may be influenced in a manner such that it is perfectly possible to operate with a very high speed and with copies of widely varying thicknesses.
[0023] It is a further aspect of the invention that the single pressure rollers 30 may be separately adjustable with respect to their minimum distance from the associated driving rollers 28, this being illustrated by an example in Fig. 3. Here the single roller 30 is mounted on the pivot arm 40 by means of a bracket arm 60, which is pivotally connected with the arm 40 through a pivot shaft 62, while the outer end of the bracket arm 60 is connected with an outer, fixed portion 64 of the arm 40 by means of a bolt 66 having at its outer end a nut 68, which is adjustable to define the said minimum spacing. On the bolt 66 there is placed plate springs 70 at both sides of the fixed arm portion 64.
[0024] In practice it is to be preferred that also the pressure rollers 30 be actively driven, which will of course be no problem if these rollers are mounted on a common shaft as shown in Fig. 2. In the embodiment according to Fig. 3 such a mounting will not be possible, for obvious reasons, but according to the invention the desired result will nevertheless be achievable when each of the rollers has a toothed wheel section, which can be driven by an engagement with a driven cog wheel mounted on a rotating shaft corresponding to the pivot shafts 62, or with a toothed belt driven from such a cog wheel, respectively from a cog wheel mounted on the shaft 42. In the preferred embodiment as illustrated in Fig. 3 the rollers 30 are driven from cog wheels on the shaft 62 which, themselves, are driven from the rotating, but otherwise stationary shaft 42.
1. A destacker for bundles of printed papers and of the type having cooperating gripping
parts for successive gripping of an edge portion of the leading paper in a supplied
bundle of printed papers, preferably a folded edge portion thereof, and for drawing
out the edge gripped copy from the bundle for delivery of the copy to a conveyor device,
preferably by the use of a mechanism for bending out the gripping edge portion into
a clamping engagement between cooperating sets of clamp rollers, which, by their rotation,
effect the drawing out of the gripped copy, the opposed, cooperating gripping parts
being arranged such that they are biased by a spring force towards each other and
are mutually movable for effecting the gripping action, characterized in that the
means for excerting the said spring force are designed such that the characteristic
of the spring force is extremely or pronounced soft, while the bias is sufficient
to ensure that both thick and thin papers can be effectively gripped and drawn out
from the bundle at high speed.
2. A destacker according to claim 1, in which the spring means comprise one or more
compressed air cylinders.
3. A destacker according to claim 1 and of the type in which the gripping parts are
arranged in distinct groups along their operative, linear gripping area, characterized
in that the gripping parts in each of these groups are adjustable for individual adjustment
of the distance or minimum distance between the cooperating gripping parts.
4. For a destacker according to claim 1 the application that in a registration system
for return newspapers it is used for destacking of newspapers from return bundles,
in which there will potentially occur newspapers with substantially different thicknesses
and with automatically readable identity markings, including an indication of a daily
edition number and/or selling district.