Conveyors: power-driven – Conveyor arrangement for selecting among plural sources or... – Plural laterally spaced locations fed to or received from a...
Reexamination Certificate
2003-12-15
2004-09-07
Hess, Douglas (Department: 3651)
Conveyors: power-driven
Conveyor arrangement for selecting among plural sources or...
Plural laterally spaced locations fed to or received from a...
C198S440000
Reexamination Certificate
active
06786328
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention is situated in the field of materials handling technology and it concerns a method and a device serving for transforming a supply stream, in which flat stream elements are conveyed with their flat expanse aligned essentially parallel to the conveying direction and in particular overlapping one another. The method and the device in particular serve for transforming a supply stream being conveyed in a loosely supported manner and comprising, as stream elements, groups of flat objects (e.g. printed products) having different formats and lying loosely on top of one another, the groups overlapping one another. This supply stream is transformed into a conveying stream, in which the groups again are conveyed loosely supported, but are at a distance from one another, so that, for example, they can be supplied to a packaging operation using a packaging material supplied from a roll.
2. Description of Related Art
Transformation of a supply stream (imbricated stream), in which individual, flat objects, such as printed products, are conveyed overlapping one another, into a stream in which the objects are conveyed behind one another and, if so required, at a distance from one another, is, according to the state of the art realized by accelerating the objects such that their spacing becomes greater than their expanse in the conveying direction. This method is unproblematic if the flat stream elements are stable and the conveying rates (in elements per unit of time) are not very high. For high conveying rates and for stream elements that are relatively long in the conveying direction, such methods give very high conveying speeds, and starting from a supply stream-with a high degree of overlap necessitates also high accelerations, for the mastering of which in particular not very stable stream elements, for stabilization, are gripped at their leading edge.
In order to circumvent the difficulties mentioned above, it is also proposed to split up an imbricated stream of the type mentioned into part streams, wherein at a switch-point stream sections are alternately supplied to one or the other of the part streams from the leading end of the imbricated stream, the stream sections being groups of overlapping stream elements. By subsequent suitable transformation, the partial streams can be made into streams in which the stream elements are conveyed one behind the other and which, due to the reduced conveying rate resulting from the splitting-up, are conveyed at a speed that is correspondingly lower than in the case described above.
The sections of the imbricated stream alternately assigned to each part stream usually are deviated from the main stream in a direction transverse to the principal surfaces of the flat stream elements (for a loosely supported imbricated stream: downwards or upwards), which deviation can be realized using a very simple device, such as a pivoting conveying substrate.
If an imbricated stream is to be directly transformed into part streams (i.e. without further transformation of the part streams) in which the stream elements are conveyed without overlap, i.e. behind one another and at a distance from one another, it is necessary to deviate from the imbricated stream not streams sections comprising a plurality of overlapping elements each, but rather individual elements. For this purpose, every element has to be gripped individually prior to the splitting-up, usually with the help of two gripper conveyors, as, for example, described in the publication EP-1063187 (or U.S. Pat. No. 6,401,903), one gripper conveyor being assigned to each longitudinal edge of the imbricated stream and one gripper conveyor being arranged on each side of the stream. In a gripping zone, the gripper conveyors run parallel to the imbricated stream, and downstream of the gripping zone they diverge. The gripper conveyors are operated in synchronism with the imbricated stream such that the grippers of one of the conveyors grip every second stream element from one side (longitudinal edge zone of the stream) and the grippers of the other conveyor grip the other stream elements from the other side. The gripped stream elements are then moved apart by the diverging gripper conveyors and are then, for example, transferred to further conveying means.
For splitting an imbricated stream as described in the last paragraph it is necessary that the two opposite edges of the flat stream elements situated on both sides of the imbricated stream can always (for all stream elements) be gripped in the same way. This means that these edges of all stream elements need to be positioned the same way in the imbricated stream. Or it means that the supplied, overlapping stream elements all have to have the same width. Splitting into more than two partial streams is not possible. For being able to grip individual stream elements it is further necessary that in the imbricated stream to be split-up the overlap of the stream elements is such that there are locations without overlap. If this condition is not fulfilled, the leading stream element needs to be laterally moved away from the supply stream before the next stream element can be gripped, which in particular in the case of stream elements of little stability is very difficult to implement.
For splitting imbricated streams by deflecting individual stream elements, it is also possible to grip the leading edge of the one stream element positioned at the leading end of the imbricated stream, as described in the publication EP-1155992. These leading edges are alternately gripped by the grippers assigned to the part streams to be established, and the gripper tracks diverge downstream of the gripping zone. For such splitting methods, the same severe conditions apply for the leading stream element edges as is the case for the lateral element edges in the method described further above. On the other hand, however, this method makes it possible to split the imbricated stream into more than two part streams. Because the leading edge of an element can only be gripped when the preceding stream element is situated at a distance from the leading end of the imbricated stream, on splitting a loosely supported stream, pairs of downstream and upstream elements have to be moved relative to one another, when only the downstream element is held gripped but not the upstream one. This can become a problem if the stream elements are unstable.
As long as the stream elements being conveyed in the imbricated supply stream are individual flat objects of the same format overlapping one another in a regular manner (regular scale spacing), the conditions as mentioned above to be fulfilled by the supply stream for being able to be split by gripping and leading apart individual stream elements according to the methods of the state of the art do not represent a problem. Even when groups of objects of the same format lying stacked one upon the other constitute the overlapping stream elements of the imbricated stream, there are no significant difficulties due to these conditions. If, however, the overlapping stream elements of the imbricated stream are groups of flat objects lying loosely upon one another and having differing formats and shapes and/or being stacked non-uniformly, it becomes considerably more difficult or even impossible to create an imbricated stream in which the mentioned conditions are fulfilled. This is in particular the case, because it is necessary, that in every gripped group all objects are gripped, but no object of a preceding or following group is gripped also.
SUMMARY OF THE INVENTION
It is an object of the invention to create a method and a device to transform, with simple means, a supply stream of stream elements (individual flat objects or groups of flat objects lying one upon the other) being conveyed overlapping one another, into at least one conveying stream of stream elements that do not overlap one another, but rather are conveyed one behind the other and possibly also beside each other. The inventive method a
Ferag AG
Hess Douglas
Rankin, Hill Porter & Clark LLP
LandOfFree
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