Patent Application
20090289409
1. Field of the Invention
The invention is the field of conveying flat, bendable objects, in particular of printed products, and concerns a device according to the generic term of the independent claim. The device serves for the separation of individual flat, bendable objects from the underside of a stack of such objects and for the onward transportation of the objects, in particular for the separation of individual printed products from the underside of a stack of printed products and for onward transportation of the printed products.
2. Description of Related Art
From publication EP1226083, a device is known which serves the purpose named above. For separation of individual printed products from the underside of the stack of printed products, the device comprises a carrier wheel, arranged below the stack, rotating on a substantially horizontal axis, on the periphery of which pairs each consisting of a suction device and a gripper allocated to the suction device are arranged. The device further comprises a supporting means, which on the one hand supports the stack from below, on the other hand comprises at least one extraction opening, through which the lowermost printed product may be gripped and for separation may be bent away from the stack towards the gripper allocated to the suction device. The carrier wheel is arranged and driven such that the suction device and gripper are moved in parallel to a pair of edges of the stacked printed products and approximately centrally between these edges below the stack. The suction devices are rotated in a controlled manner during the rotation of the carrier wheel and connected to a suction pipe and de-coupled from it. The grippers are closed and re-opened in a controlled manner during the rotation. When a suction device is moved through underneath the stack, it grips the lowermost printed product in the region of the edge orientated transversally to its direction of movement it meets first, and when moving further it bends this edge region downwards through the extraction opening in the supporting means into the open allocated gripper, which then grips the printed product and removes it completely from the stack during its further movement.
In an embodiment described in publication EP1226083, the supporting means on which the stack rests is a roll bed conveyor, which comprises a plurality of rollers arranged horizontally and in parallel to each other and are mounted to be freely rotatable, and which are aligned to the suction devices and grippers but are moved through below the stack on a substantially rectilinear and horizontal path. Hereby, the movements of the rollers and the suction devices are adjusted in relation to one another such that the suction device may grip the lowermost printed product of the stack in-between two successive rollers and may draw out its edge region, and the upstream roller of the two may move in-between the printed product gripped by the suction device and the printed product resting thereupon. The roll bed conveyor thus forms a succession of extraction openings orientated in parallel to the rollers and to the printed product edges gripped by the suction devices, which openings successively move through beneath the stack. In order for the stack to be securely supported and for the extraction openings to be large enough all the same, it is suggested to move the rollers through beneath the stack in groups of three, wherein the rollers within the groups of three are at smaller distances from each other and wherein between succeeding groups a larger interspace is provided and only this interspace is used as an extraction opening. The rollers forming the roll bed conveyor underneath the stack consist of two mutually aligned roller sections, which are at a distance from each other. Thus, it is prevented that the suction devices conflict with the rollers. A circulating chain is provided on each side of the carrier wheel, one for the left roller sections and one for the right roller sections, wherein the roller sections are coupled to these chains and revolve with the chain at constant distances to each other. The orbit of the chains on both sides runs around a deflection roller arranged coaxially to the carrier wheel and around a further deflection roller with a parallel axis, which is arranged such that an upper part of the orbits is approximately horizontal between the deflection rollers. The stack is arranged above this region of the orbit of the rollers.
The device according to EP1226083, thus, comprises a revolving roll bed conveyor with extraction openings, wherein the stack is arranged on the outside of this roll bed conveyor. When separated from the stack of printed products, the printed products are drawn through an extraction opening to the inner side of the circulating roll bed conveyor, from where they need to reach its outer side for being conveyed further. For this purpose the roller sections in the corresponding region are rotated into a substantially vertical position in their orbit. In this region the printed products are laid down on a conveying belt and released by the grippers, wherein the conveying belt follows the circular movement of the grippers in a substantially tangential manner.
The device described in publication EP1226083 works without problems and without requiring much space. It is, however, a costly device, and is restricted regarding the direction of onward transportation.
In publication WO 2008/0000099, a device is described which serves the same purpose. Again, a roll bed conveyor is on hand, wherein the rollers of the roll bed conveyor are fitted to a roller wheel, which e.g. circulates on the same axis as the carrier wheel. The drawn out printed products are, however, not drawn completely into the inner region of the roll bed conveyor, but only partly. In this position, the printed products are conveyed in synchrony with the roll bed conveyor over a certain distance and then deposited on a transport track. Thus it is not—as in EP1226083—necessary to open the roll bed conveyor in a certain region in order to transport the printed products outwards from the inside of the roll bed conveyor. Therefore, the orientation of the rotation axis of the rollers remains unchanged and the rollers circulate on a non-circular orbit, on which the distances between the rollers are varied. For this purpose the rollers are flexibly linked to the roller wheel by means of levers, such that the levers are rotatable in parallel to the rotation plane of the roller wheel. A definite orbit and a definite and consistent course of movement of the rollers along this orbit are defined by a roller guidance, which controls the movement of the rollers along the orbit.
Publication EP1254855 also shows a roll bed conveyor, in which the rollers are fitted to a roller wheel. In order to open the roll bed conveyor in a certain region, the rollers are tilted away on a tilting axis, which is substantially radial or secantial respectively in relation to the roller wheel. For rotating the rollers, a cam control is provided. A wheel rolling on a cam moves the rollers via a lever mechanism with several levers. Because of unfavourable leverage due to the relatively long rollers and the tilting point of the rollers being near the lever mechanism the forces developed on the lever mechanism, are considerable and conversely the resulting movement of the rollers is not defined to complete precision.
The invention thus has the object to create a device for the same purpose as the devices described above, which is, however, more simple in design and effects a flowing, precise movement of the rollers.
This object is achieved by a device with the characteristics according to claim 1.
The device for separation of individual flat, bendable objects from the underside of a stack of such objects and for the onward transportation of the objects thus includes:
a stacking space with a supporting arrangement supporting the stack from beneath,
circulating separation and transportation devices for separating the objects from the underside of the stack and
an arrangement for onward transportation of the separated objects.
Hereby the supporting arrangement is a roll bed conveyor formed by a plurality of circulating rollers, wherein the rollers are respectively rotatable around their longitudinal axis and are moved along an orbit and thereby are moved through below the stack in a supporting region in a manner aligned to the separation and transportation devices.
The rollers are respectively coupled by means of a coupling to at least one roller wheel and by means of this coupling the longitudinal axes of the rollers each can be pivoted in relation to the roller wheel. The rollers are pivoted in a release region of the orbit by a controlling element and, thus, produce an opening of the roll bed conveyor, through which opening the arrangement for onward transportation is routed.
The separation and transportation devices, thus, draw the objects through the (not opened) supporting region into an inner region of the roll bed conveyor. The roll bed conveyor is opened for outward conveying of the objects in a release region, in which the objects again leave the inner region.
Due to the rollers being arranged on a roller wheel—and not on a belt or on a chain—a very simple design of the roll bed conveyor is possible.
The rotation of the rollers and, thus, the opening of the roll bed conveyor in the release region are preferably implemented by means of a preferably fixed control curve or cam, e.g. in that the rollers roll on the control cam. Hereby, advantage is taken from the fact that the rollers are preferably mounted in a roller carrier in a manner rotatable around their longitudinal axis. Thus, a rigid control cam may easily be used without further movable control elements. The control cam is advantageously arranged on the inside of the orbit and presses the rollers or the roll bed conveyor, respectively, open from the inside. Alternatively, the rollers may be extended backwards beyond the roller carriers such that the rear ends of the rollers are pressed towards each other by a control runner or cam, which is arranged outside the roll bed conveyor, and thus the front ends of the rollers are moved away from each other. Other mechanical, pneumatic, hydraulic or electrical operation means may also be used for the pivoting of the rollers.
The roller carriers are advantageously mounted on the roller wheel to be pivotable around a rotation axis. In the supporting region the longitudinal axes of the rollers preferably run substantially in perpendicular to the plane or the rotation plane of the respective roller wheel. This perpendicular position is preferably defined by a mechanical stop, which limits the rotation movement in a corresponding stopping position. Basically, it is also possible to incline the roller wheels and to form the stop such that the rollers run, in the region of the stack, where they serve as support, in parallel to the underside of the stack (in general horizontally).
By means of the control runner or cam, on the one hand, and the stop on the other hand a simple movement control device consisting of few parts with favourable leverage and therefore a precise guidance of the roller movement is created.
A preferred embodiment of the invention includes a pre-tensing device, which respectively draws the roller carriers, and thus their rollers, in the direction of the stopping position of the pivoting movement. In a particularly simple, preferred embodiment, the pre-tensing device comprises an elastic pulling cable, which connects roller carriers of the individual rollers of a roller wheel to each other and thus draws all these roller carriers and with them their rollers into the direction of the stopping position of the rotation movement. In a different preferred embodiment the pre-tensing device comprises a set of spring elements, wherein an individual spring element is allocated to each roller, which effects a load between roller and roller wheel, wherein this load draws the roller into the direction of the stop.
In a preferred embodiment of the invention, the rollers are freely rotatable and are, at least in a section of the orbit, preferably at least in the supporting region, rotatable by rolling on a rolling-off body, wherein this rotation corresponds to a rolling movement of the rollers on the bottommost object of the stack. Thus, the rotation of the rollers is effected by the rolling-off body and not by the bottommost object, which prevents damage of this object.
The rolling-off body is preferably a cable tensed around a sector of the orbit from the outside. It may also be a fixed rail or runner against which the rollers are guided.
The device according to the invention preferably includes two opposing roller wheels with facing, preferably mutually symmetric sets of rollers. The axes of the two roller wheels are advantageously coaxial, can, however, also e.g. be inclined towards the inside of the device. For certain applications, however, one single roller wheel may be adequate.
In a preferred embodiment of the invention the at least one roller wheel and the carrier wheel of the suction devices and grippers comprise parallel rotation axes, which makes a simple design possible. Furthermore, preferably the carrier wheel and the at least one roller wheel are driven at identical angular speeds, preferably by the same drive and coupled through a gearbox.
Further preferred embodiments emanate from the dependant claims.
In the following, the object of the invention is explained in more detail on the basis of preferred embodiment examples, which are shown diagrammatically in the attached drawings. Hereby:
The reference numerals in the drawings and their denotations are summarized in the reference numeral list. In the figures identical parts are basically denotated with identical reference numerals.
In a second region of the orbit 11, referred to as release region 13 in the following, the rollers 9 are pivoted by a control runner or cam 15 out of the normal direction to the plane of the drawing. A tensioning or pulling means, here a tensioning cable or pulling cable 18, draws the rollers back against a stop in this direction.
The following elements concern the transport of the flat objects through the device. Elements arranged and acting in analogy are described in more detail in the publications EP1226083, EP1254855 and WO 2008/0000099, which are summarized further above. Thus,
The pulling cable 18 made of elastic material connects the individual roller carriers 17 to each other, i.e. it runs through the individual roller carriers 17 of a roller wheel 7, along the perimeter of the device. For this purpose the pulling cable is e.g. hooked into a respective hook 24 of the roller carriers 17. Hereby, it may slip in hook 24 in relation to roller carrier 17, or it may be fixed. The pulling cable 18 hereby draws the roller carriers 17 and therewith the rollers 9 inwards in the direction of the position in which the longitudinal axes 10 are in perpendicular to the plane of the roller wheel 7. This position is defined by a stop 16 (
In the release region 13, the rollers 9 are pressed outwards and pivoted by the control runner or cam 15 against the spring load of the pulling cable 18 (
In
| Number | Date | Country | Kind |
|---|---|---|---|
| 00787/08 | May 2008 | CH | national |
