Abstract:
An apparatus for conveying and discharging flat, preferably flexible articles, in particular printed products, the apparatus including a plurality of grippers which can be moved in a conveying direction (F) along a continuous conveying path (U) defined by a conveying mechanism. The grippers include a first gripper jaw and a second gripper jaw, which can assume a clamping position and an open position relative to one another. The first gripper jaw is longer than the second gripper jaw and includes a first gripper part, which in the clamping position interacts 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 of the first gripper jaw relative to one another is variable and can be adjusted by a control means.

Description:
BACKGROUND OF THE INVENTION 
     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. 
     BRIEF SUMMARY OF THE INVENTION 
     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. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Examples of the invention are represented in the drawings and are described hereinafter. There are shown in a purely schematic manner in: 
         FIG. 1  a perspective view of a gripper of a device according to the invention; 
         FIG. 2  the gripper of  FIG. 1  in a view in the conveying direction, 
         FIGS. 3   a  and  3   b  the transfer region of a device according to the invention, at different points in time with the release of objects; 
         FIG. 4  another part region of the conveying path, in which objects are introduced into the opened grippers; 
         FIG. 5  another part region of the conveying path, in which objects are conveyed by the closed grippers in a hanging manner; 
         FIG. 6  a perspective view of a further gripper of a device according to the invention; 
         FIG. 7  a detail of the joint region of the gripper of  FIG. 6 ; 
         FIG. 8  the gripper of  FIG. 6  in a view in the conveying direction; and 
         FIGS. 9   a  and  9   b  the transfer region of a device according to the invention, with a gripper according to  FIG. 6  at different points in time with the release of objects. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  shows a perspective view of a gripper  10  of a device  1  according to the invention. Details of the device are shown in the  FIGS. 3   a ,  3   b ,  4  and  5 . The device  1  comprises several grippers  10  which are attached on a conveying member  20  in the form of a chain with several chain members  21 . In this example, each second chain member  21  carries a gripper  10 . Also each chain member  21  may be provided with a gripper  10 . The shape of the conveying path U is set by a channel  23 . The chain rolls in the channel  23  by way of guide elements  22  in the form of rollers and this chain moves the grippers  10  in the conveying direction F which corresponds to the channel direction. The conveying path U for example has linear regions (FIGS.  4 + 5 ) or curved regions with a certain radius of curvature R ( FIG. 3   a+b ) or with a variable curvature. 
     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  ( FIG. 2 ), serve for transferring the gripper  10  into the clamping position. In the clamping position, the gripper  10  is locked by the lever  33 . Product unevenness is compensated by way of both fingers  18  being resilient independently of one another by way of spring  31 . The gripper  10  is opened by way of an opening element  35  ( FIGS. 2 ,  3   a+b ) acting on the locking  33  and pressing this away. The opening element  35  may be switchable, i.e. with selected collections, the opening element  35  is displaced such that the respective lever  33  is not actuated and the gripper  10  is not opened, and the collection of products (or an individual product) which is held in the gripper  10 , is not released. Thus the collection may be conveyed back and ejected or supplemented. 
     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  FIGS. 3   a  and  3   b ) A first surface of this shape part  19  serves as a first gripper part  13 , i.e. may cooperate with the second gripper jaw  12  in a clamping manner. A second surface of this shape part  19 , which projects therefrom roughly at right angles, serves as a base surface  17  of the gripper  10  and forms an abutment  16  for the products to be accommodated. A second gripper part  14  is connected at the distal end  13   a  of the first gripper part  13  to this gripper part via a joint  15 . For this, the distal end  13   a  of the first gripper part  13  has a reinforcement  13   b , for example. The second gripper part  14  is a two-dimensional, flexible element, and/or is designed according to the course of the revolving path U with regard to its shape. In the second case, the second gripper part is curved such that its curvature centre in the transfer region coincides with the centre M of the curvature of the revolving path U. A width b of the second gripper part  14  is smaller than a typical product width B. The second gripper part  14  on its rear side (not visible in  FIG. 1 ) is connected to a control mechanism  40  for setting its orientation. The control mechanism  40  has a rigid lever  41  with the length L. The lever  41  is articulately connected to the reinforcement element  42  part on the second gripper part  14  and to a bearing element  43 . The respective pivot axes are indicated at A 1  and A 2  respectively. The first pivot axis A 1  has a distance d&gt;0 to the joint  15 . The distance d is about a third to a quarter of the total length of the second gripper part  14 . The bearing element  43  here is attached on the adjacent chain member  21  which trails in the conveying direction F. The bearing element  43  could also be designed or fastened on a subsequent gripper  10 , i.e. the lever  41  could be attached directly on the subsequent gripper  10 . If the second gripper part  14  is sufficiently stable, one may also make do without the reinforcement element  42 . 
     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  FIG. 2 , the aligning unit  60  for example comprises aligning elements  61  arranged laterally of the conveying path U, whose distance may be adjusted. 
     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  FIGS. 3   a  and  3   b , it is here a belt conveyor with a conveyor belt  52  which forms an essentially plane conveyor rest  51  for products to be taken over. The optionally switchable opening element  35  acts on the locking  33  at an opening location S 1 , in order to open the grippers  10 , so that the transfer may take place. 
       FIG. 4  finally shows an example for the receiving of the products  100  into the grippers  10 . The products  100  are introduced into the open grippers by a feed unit  70 . Also further feed units (not drawn) may be present for introducing further products. The grippers are closed at a closure location S 2  by way of a suitable cam. 
     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  FIG. 3   b ) of its pivot axis A 1  to the joint  15  are selected such that the second gripper part  14  in a view transverse to the conveying direction F is roughly aligned to the first gripper part  13  when the conveying path U is straight. This situation is shown in FIGS.  4 + 5 . The lever  51  here is orientated perpendicularly to the conveying direction F. The gripper parts  13 ,  14  are inclined by roughly 20-60° opposite to the conveying direction F. In this position therefore, a largely plane rest surface is formed by the first gripper jaw  11 . The objects  100  may now be introduced along this rest surface into the opened grippers  10  ( FIG. 4 ). The objects  100  abut on the abutment  16  and are laterally aligned, as the case may be, by the aligning unit  60  ( FIG. 2 ). When required, further feed units  70  may be present, which lay further objects onto the already received objects  100 . Thereby, the objects  100  are supported from below in a surfaced manner by way of the first gripper jaw  11 . 
     After the lateral aligning, the grippers  100  are closed at the closure location S 2 . 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  FIG. 5 , the conveying upside down is also possible. The trailing free edges  101  of the objects  100  preferably hang freely or slide on a stationary support surface  80  or are supported by way of a co-running conveying means, for example a belt. 
     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 A 2  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  FIG. 3   a . The length of the lever  41  and the position of the axes A 1 , A 2  are selected such that the second gripper part  14  at least in the region of the joint  15  (or the reinforcement element  42 ) is aligned roughly concentrically (with a shape-stable and curved second gripper part  14 ) or tangentially (with a flexible second gripper part  14 ) to the conveying path U. If the conveying path in the transfer region is described roughly by a circular segment with a radius R and centre M, the second gripper part  14  thus runs roughly tangentially to or on a circular segment K with a larger radius R′&gt;R and with the same centre M. With a shape-stable and curved second gripper part  14 , its curvature, thus, corresponds to the inverse of this larger radius K′. The conveyor surface  51  of the conveying-away device  50  likewise runs tangentially to this circular segment K. The speed of the conveying surface  51  is preferably at least approximately equal to the speed of the objects  100  and thus also approximately equal to the speed of the gripper on the circular segment K. 
     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  FIG. 3   b . Thus one succeeds in a well controlled transfer, with which the objects are guided until their leading edges  102  have left the grippers  10 . 
       FIG. 6  shows a further gripper  10  which is basically constructed as the gripper of  FIG. 1 . Parts which correspond to one another are provided with the same reference numerals. The differences are dealt with hereinafter. 
     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 ( FIG. 6 ). The second gripper part  13  has a region  13   c  with a reduced thickness, in which its upper side is slightly curved, so that the upper side  91  of the continuation  90  does not project out of the support surface. 
       FIG. 7  shows the condition, in which the first and second gripper part  13 ,  14  are pivoted relative to one another out of the straight position ( FIG. 6 ). The continuation  90  is now lifted from the first gripper part  13 . 
     As may be particularly recognised from  FIG. 8 , the second gripper part  13  in contrast to  FIG. 1  is not rectangular, but is designed in a laterally projecting manner towards the outer end. 
     The function of the continuations  90  is explained by way of  FIGS. 9   a+b . The objects  100  are deformed on transfer to the conveying-away device  50 , since their leading edge  102  is still held between the first gripper part  13  and the second gripper jaw  12  and is bent upwards, whilst the trailing part of the object  100  already lies on the horizontal conveying surface  51  and is pressed by the second gripper part  14  against the conveyor surface  51 . On opening the gripper  100 , the lifted front edge  102  provides an engagement surface for the head wind. It may therefore occur that the object  100  is not cleanly deposited, but dislocates on deposition. This is undesirable. 
     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  FIGS. 6 and 7 .