1. Field of the Invention
The invention lies in the field of conveying technology and relates to a device and to a method for conveying and releasing flat, preferably flexible objects, in particular printed products, based on a gripper conveyor. The further development according to the invention in particular serves for the controlled release of the objects.
2. Description of Related Art
In printing technology, in particular with the production of newspapers, increasingly more complex objects are conveyed and/or processed in other manners with larger and larger speeds. Such objects are for example printed products, such as newspapers, magazines, brochures, books or also credit cards, CDs, goods samples and likewise. These are selected individually and are collated into collections.
The high speeds and the complexity of the products demand very exact control of the position of the individual constituents at every point in time of the processing, in particular with the transfer of products between two installation parts of a complete installation. With the transfer of objects from a gripper conveyor to a further station, e.g. a conveyor belt, the grippers for example are merely opened, and the objects come to lie on the conveyor belt due to gravity. Thereby, it may occur that the individual products which were commonly held by the gripper, dislocate or rotate with respect to one another. This may lead to defects with the further processing.
It is, therefore, the object of the invention to further develop a gripper conveyor in a manner such that a well controlled release of the held objects is possible, in particular a deposition on a conveyor surface.
The device for conveying and releasing flat and preferably also flexible objects, in particular printed products, comprises a plurality of grippers which are movable in a conveying direction along a closed conveying path which is defined by a conveyor member, e.g. a chain with several chain members. The grippers comprise a first and a second gripper jaw which may assume a clamping position and an open position relative to one another. According to the invention, the first gripper jaw is extended with respect to the second gripper jaw. It comprises a first gripper part which in the clamping position cooperates with the second gripper jaw, and a second gripper part which in the clamping position projects beyond the second gripper jaw. The orientation of the first and second gripper parts relative to one another is variable and may be set with a control device.
In the operating method, the closed grippers, with objects received therein, are moved to a transfer region and the grippers are opened there. The second gripper parts are controlled in a manner such that they press the objects in the transfer region against a conveyor rest of a conveying-away device, in particular already shortly before the opening, and until the object lies completely on the conveyor rest
The device makes do without additional co-moved guide elements for stabilising and positioning the objects to be released, by way of the controllable second gripper parts.
The objects to be released may, for example, be guided in a controlled manner, for example with the transfer to a further component of the complete installation, by way of the orientation of the first and second gripper parts being changeable relative to one another in a controlled manner. Hereby, they cooperate with external counter-elements for example. Thereby, pressure may also be exerted on the object by way of the actively controlled, movable second gripper part. Displacements of the held objects are thus avoided with and after the opening of the grippers.
The grippers according to the invention may, for example, be realised on the basis of conventional grippers with essentially equally long gripper jaws. One of these “conventional” gripper jaws according to the invention is provided at its distal end with a movable continuation which projects beyond the other gripper jaw. The respective gripper jaw with the continuation in the context of the invention is indicated as a whole as “first gripper jaw”. That part of this first gripper jaw which together with the second gripper jaw carries out the conventional clamping function, is indicated as “first gripper part”. The continuation is indicated as “second gripper part”. The connection, in particular, is realised by way of a joint.
Preferably, a conveying-away device with a plane or essentially plane and compliant conveyor rest is present, in particular a belt conveyor. This device is arranged relative to the gripper conveyor such that objects released by the grippers are deposited onto the conveyor rest supported by gravity, i.e. from the top. The region, in which the conveying path of the gripper conveyor approaches the conveying-away device to such an extent, that the transfer may take place, is indicated as the transfer region. The gripper conveyor in the transfer region has an opening device for the grippers. The objects are pressed against the conveyor rest in a preferably surfaced manner by way of second gripper parts, before, during and after the opening of the grippers. The control device thus preferably sets a minimum distance between the second gripper parts and the conveying path of the grippers, which is not fallen short of with the transfer.
Preferably, the object is held between the second gripper part and the conveying-away device in a clamping manner, during and after the opening of the grippers, until the complete release to the conveying-away device. The speeds of the gripper and of the conveying-away device are adapted to one another for this.
The objects on release to the conveying-away device may be accompanied over an extended stretch and thereby be fixed, by way of the orientation of the second gripper part being varied in a controlled manner. Its orientation for this is set, for example, such that it is adapted (e.g. running parallel) to the counter-element, e.g. to the conveyor rest of the conveying-away device, in order to achieve a surfaced clamping effect.
Alternatively or additionally, the second gripper part may be flexible for achieving a surfaced effect, so that it may roll on the object or on the counter-element. In this case, the second gripper parts in the transfer region at least in the vicinity of the connection to the first gripper part, preferably have an orientation which is roughly parallel to the conveying path. The conveying path is preferably curved in the transfer region. The second gripper part in a view transverse to the conveying direction is thus orientated tangentially to a circular path which has the same centre as the conveying path, but a larger radius.
Controllable second gripper parts may be realised in a mechanically simple manner. Since the gripper jaws in the normal case are distanced from their conveyor member, a change of the path curvature of the conveying path leads to the distances of two reference points on adjacent grippers also changing. Such a distance change, for example, also occurs between a reference point on a gripper and the conveyor member, e.g. a subsequent chain member. Therefore, the orientation of the second gripper part may be controlled by way of a suitable mechanical coupling between the second gripper part and a subsequent gripper or the conveying member. For this, the second gripper part is coupled, for example, mechanically to the mentioned elements, e.g. via a lever. A separate control cam independent of the actual grippers or their conveyor member is also possible, but is mechanically more complicated.
The first gripper part and the second gripper jaw in each case have an elasticity or stiffness which in a clamping position permits an adequate clamping effect. A certain flexibility or spring effect may exist for compensating differently thick products. One may also compensate thickness variations within the gripped objects by way of the second gripper jaw comprising several separately resilient fingers which together cooperate with a first gripper jaw.
In a preferred embodiment of the invention, the second gripper part is designed in a comparatively shape-stable or stiff manner, thus without (as in the subsequent embodiment) an elasticity of the second gripper part being given an essential function. The second gripper part is curved according to the path course of the conveying path in the transfer region, so that if the second gripper part is located in the transfer region, the curvature of the second gripper part runs concentrically to the conveying path in the transfer region, thus with a different radius, but with the same centre. If here and hereinafter one speaks of the curvature of the second gripper part, then with this, one means the curvature at an outer surface of the second gripper part, i.e. the surface on which the products bear. The second gripper part may roll on the object to be released or on the conveyor surface on account of its shape, during or after the second gripper part transfers an object onto a for example plane or approximately plane, compliant conveyor surface of the conveying-away device. The second gripper part may therefore cooperate with the objects in a surfaced and not only pointwise manner or along a line.
In another embodiment of the invention, the second gripper part has an elasticity which is larger than that of the first gripper part. The second gripper part on account of its deformability may roll on the object to be released or on the conveyor surface, during or after the second gripper part transfers an object to a, for example plane, conveyor surface of the conveying-away device. The second gripper part may therefore cooperate with the object in a surfaced manner and not only in a pointwise manner or along a line. The elasticity is preferably not so large that the second gripper part no longer acts as a rest surface or support surface. The elasticity is therefore selected such that the second gripper part does not essentially deform by way of the weight force of the gripped collection of products. These elastic second gripper parts may thus be realised with as well as without the mechanical control of their orientation.
An even better controllable product release is achieved by way of at least one flexible continuation which projects from the second gripper part and reaches into the region of the first gripper part, being connected to the second gripper part. The upper sides of the continuation and of the second gripper part are preferably flush with one another. In the extended condition of both gripper parts (upper sides aligned to one another), the continuation lies on the upper side of the first gripper part, wherein the respective upper sides are aligned to one another. In the angularly bent condition of the two gripper parts (upper sides orientated at an angle to one another), the continuation projects from the first gripper part. On opening the gripper therefore, the object is pressed away from the first gripper part by the continuation, for example towards a conveying-away device. Product dislocation on release is additionally avoided by way of this.
Apart from the support function with the product release, the extended first gripper jaw may assume an additional function. At least in the open position of the gripper, it preferably forms a rest surface for the objects. For this, preferably at least its second gripper part is so wide in a direction transverse to the conveying direction, that objects may be deposited thereon in a stable manner. The second gripper part may e.g. be wider than the second gripper jaw. The gripper may also be applied for collating objects by way of this: different printed products, e.g. intermediate products or supplements may be supplied to the opened gripper and may be laid onto one another whilst forming a stack. The gripper, thus, on collation additionally assumes the function of a pocket conveyor. The orientation of the second gripper part is thereby preferably set such that the support function is fulfilled, thus the second gripper part does not yield under loading. Preferably, the first and second gripper part is aligned to one another in the region of the conveying path, in which the collation is carried out.
For example, a plurality of feed devices are present for feeding the objects into the grippers, and the exits of these feed devices lie behind one another in a collation region of the conveying path, in a row essentially parallel to the conveying path.
An aligning unit may also be present, which laterally aligns the objects arranged in the open grippers. For this, it is advantageous, but not absolutely necessary for the second gripper parts to be less wide transverse to the conveying direction than a typical object width.
The invention is advantageously applicable in all cases, with which a well controllable transfer of objects from a gripper conveyor to a station such as e.g. a conveying-away station, in particular to a belt conveyor, is desired.
Preferably, the function of the release, thus the opening of the grippers for letting go of the held collection of products may be switched, so that selected collections are not released, but remain in the gripper and are led back. With this, a correcting function may be realised by way of defect collections being ejected or missing products being supplemented by a device for collation (“repaired”) with a renewed passage.
Examples of the invention are represented in the drawings and are described hereinafter. There are shown in a purely schematic manner in:
a and 3b the transfer region of a device according to the invention, at different points in time with the release of objects;
a and 9b the transfer region of a device according to the invention, with a gripper according to
The grippers 10 comprise two gripper jaws 11, 12 which in each case form a functional unit, but may consist of several elements. The shorter second gripper jaw, here for example, comprises two separate fingers 18 which are arranged next to one another transversely to the conveying direction. A pivot mechanism 30 is present, with which the gripper jaws 11, 12 may be adjusted relative to one another. The pivot mechanism 30 comprises control elements in the form of cam rollers 32 and a locking 33. The cam rollers 32, together with a control cam 34 (
The longer first gripper jaw 11 is constructed as follows: it comprises a shape part 19, e.g. a bent sheet metal piece, which is L-shaped in a lateral view (see
An aligning unit 60 is arranged in part regions of the conveying path U and may act on the objects in the grippers 10. As is shown in
A conveying-away device 50 is, for example, present in a further part region of the conveying path U. The region, in which the device cooperates with the conveying away device 50, is also indicated as a transfer region. An example of such a conveying-away device 50 is shown in
The function of the device 1 and the grippers 10 is described hereinafter, particularly with regard to the controlled transfer of products to the conveying-away device 50:
The length L of the lever 41 and the distance d (see
After the lateral aligning, the grippers 100 are closed at the closure location S2. The objects are held in a clamping manner between the second gripper jaw 12 and the first gripper part 13 of the first gripper jaw 11. In the clamped condition, they are conveyed over an infinite stretch along the conveying path U. As shown in
The objects are released in a curved part of the conveying path U. With the transition from the linear into the curved part, the distance between the second pivot axis A2 and any point on the first gripper part 13 (e.g. to the joint 15) increases. Since the length L of the lever 41 is constant, the second gripper part 14 is pivoted relative to the first gripper part 13 and is pulled towards the conveying member 20. This is shown in the left region of the drawing in
The second gripper parts 14 press an object 100 therefore in a surfaced manner against the conveying surface 51, whilst this object is released from the gripper 10. Since the second gripper parts 14 are shaped concentrically to the path course or are flexible, they roll together with the object 100 on the conveyor surface 51 and accompany the objects 100 on transfer, until its leading edge 102 has left the gripper 10.
Alternatively, the orientation of the second gripper parts 14 may also be controlled such that the second gripper parts 14 at least in a part region of the transfer region run roughly parallel to the conveying surface 51 and also accompany the objects 100 in this manner.
The gripper 10 is opened if or after the clamping or stabilising effect has been created between the gripper part 14 and the conveying surface 51. This is represented in
The main difference lies in a flexible continuation 90 which is connected to the pivotable second gripper part 14 of the extended first gripper jaw 11. The continuation 90 is a thin element which is rectangular in a plan view and which is flexible by way of a suitable selection of the shape or of the material. The continuation 90 consists, for example, of spring steel.
In each case, a continuation 90 is located on the outer lateral edge of that edge of the second gripper part 14 which faces the joint 15. The continuation 90 points towards the gripper jaw or to the abutment 16 and is aligned with the second gripper part 14. The continuation 90 lies on the first gripper part 13 in the condition, in which the first and second gripper part 13, 14 form a continuous, essentially plane support surface with one another and are aligned with one another (
As may be particularly recognised from
The function of the continuations 90 is explained by way of
Continuations 90 counteract the lifting from the conveyor surface 51, by way of them also pressing the leading part of the object onto the conveyor surface 51 after opening the gripper 100. By way of this, the gap between the object 100 and the conveyor surface 51 is directly closed after opening the gripper 10. In the closed condition of the gripper 10, the continuation 90 on account of its flexibility is bent as the gripped object 100. In the open condition, it assumes its rest position represented in
Number | Date | Country | Kind |
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1724/08 | Nov 2008 | CH | national |
553/09 | Apr 2009 | CH | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/CH2009/000231 | 7/2/2009 | WO | 00 | 6/9/2011 |