Patent Publication Number: US-2023136370-A1

Title: Method of moving a stack of products by use of a robot

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation of copending patent application Ser. No. 17/169,786, filed Feb. 8, 2021, which claims the priority, under 35 U.S.C. § 119, of German patent application DE 10 2020 103 398.2, filed Feb. 11, 2020; the prior applications are herewith incorporated by reference in their entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to a method that has the features described in the preamble of the independent claim. 
     The technical field of the invention is the graphic industry and in particular the field of handling (e.g. gripping, holding, moving, rotating, turning and/or depositing) stacks of products, preferably stacks of printed and folded flat products, preferably made of paper, board, metal, or a composite material, by means of a manipulator, in particular a robot or an articulated robot. 
     It is known manually to transport stacks of products such as folded signatures from the delivery of a machine for further processing such as a folder to a pallet and to deposit them there in accordance with a known deposit scheme. This task puts a lot of strain on the body because four to five stacks of products need to be moved every minute. It is also known to use an articulated robot for this purpose, for instance a product called “CoBo-Stack” manufactured by MBO Maschinenbau Oppenweiler Binder GmbH &amp; Co. KG based in Oppenweiler, Germany. 
     In  FIG.  11   a   , Japanese patent application JPS6048848A discloses gripping a stack of products at diagonally opposite corners and in  FIG.  9   , the document discloses a sagging of the stack. The two illustrated grippers belong to two separate robots. 
     U.S. patent publication No. US 2006/263196 A1 discloses to rotate and turn a stack by means of a robot gripper. 
     European patent EP1645434B1, corresponding to U.S. Pat. No. 7,607,882, discloses to pivot a stack of products into an upright position and to transfer the stack of products to a clamp/to grip the stack of products from above. 
     European patent EP2128056A1 discloses a robot with an articulated arm for handling a stack and, in  FIG.  4   , a gripping device. 
     German utility model DE202019106975U1, corresponding to U.S. patent publication No. 2020/0354167, discloses a handling device for transferring a stack of products, the handling device containing a gripping unit movable in three dimensions. The gripper unit contains first and second lateral faces and a respective upper and lower holding element supported for linear movement along a respective lateral face. 
     BRIEF SUMMARY OF THE INVENTION 
     An object of the present invention is to provide an improvement over the prior art in particular in such a way that stacks of products may be moved in an automated way and deposited, in particular in a turned or unturned arrangement. 
     In accordance with the invention, this object is attained by the method recited in the independent claim. 
     Advantageous and thus preferred further developments of the invention will become apparent from the dependent claims as well as from the description and drawings. 
     The invention relates to a method of method of moving a stack of products by means of a robot, the robot containing an articulated arm and at least one gripper disposed on the articulated arm to grip the stack of printed products and the stack of products selectively being turned. The invention is characterized in that the stack of products is pivoted through an effective angle α 1 &lt; &gt;180° and subsequently pivoted through an effective angle α 2 =180°−α 1  or pivoted back through an effective angle α 2 =−α 1 . 
     The invention advantageously provides a way of moving stacks of products in an automated way and in particular to deposit it in a turned or unturned arrangement. 
     In accordance with the invention, the stack of products is advantageously pivoted in two steps and selectively turned in the process. A first pivoting step is through an effective angle α 1 &lt; &gt;180°. The second step is pivoting through an effective angle α 2 =180°−α 1 . If α 1  and α 2  both equal 90°, for example, in accordance with the invention a turn through 180° is made. If α 1  and α 2  are 90° and −90°, for instance, no turn is made in accordance with the invention. 
     The two-step pivoting process of the invention advantageously provides an opportunity to introduce intermediate steps such as vibrating or straightening the edges of the stack of products. In addition, the two-step pivoting process of the invention makes it possible to carry out the two steps at different positions, for instance in that the robot carries out a movement in between. In addition, the two-step pivoting process of the invention advantageously allows the two steps to be carried out by different devices, for instance the robot and a pivoting device that is different from the robot. 
     The “effective angle” is understood to indicate that the angle is independent of the type of the pivoting movement. An effective angle of +90° may therefore be attained by a pivoting movement through +90°, two pivoting movements through +45° each, or a pivoting movement through −270°. Instead of “effective angle”, just the term “angle” may be used. 
     “Selectively” is understood to mean that the stack of products is either turned or not turned. The selection may preferably be made by a digital computer, in particular as a function of what is known as a deposit scheme. “Selectively” is further understood to indicate that the method may be carried out multiple successive times with respective stacks of products and that in the process, at least one stack of products is turned and at least one stack of products is not turned. 
     Further Developments 
     The following paragraphs describe preferred further developments of the invention (in short: further developments). 
     A further development may be characterized in that the pivoting through the effective angle α 1  is achieved by a pivoting device different from the robot. The pivoting device may be assigned to a delivery of a machine for further processing, in particular a folder, and may in particular be disposed thereon. It may comprise a pivotable gripper for the stack of products. The pivoting device may be controlled by a digital computer. The pivoting device preferably pivots the stack of products through α 1 =90°. 
     A further development may be characterized in that the step of pivoting through the effective angle α 1  occurs before the step of moving, i.e. in that the step of moving starts from the pivoted position of the stack of products. The movement is preferably achieved by the robot arm. 
     A further development may be characterized in that the step of pivoting through the effective angle α 1  occurs about a horizontal axis. The axis may be aligned to be parallel with the direction of transport of a delivery of a machine for further processing, in particular a folder. Before it is pivoted, the stack of products is preferably gripped and held. 
     A further development may be characterized in that when the stack of products is pivoted through the effective angle α 1 , it is pivoted out of a horizontal position. In the horizontal position, the individual products, for instance folded signatures, in the stack of products are preferably horizontal. 
     A further development may be characterized in that when the stack of products is pivoted through the effective angle α 1 , it is pivoted into a vertical position. In the vertical position, the individual products in the stack of products are preferably upright. 
     A further development may be characterized in that the stack of products is aligned and/or straightened in one direction and/or straightened in two directions perpendicular to one another and/or vibrated and/or aerated when it is not in a horizontal position and/or in that a fanned-out stack of products is transformed into an unfanned stack (“unfanning”). During this process, the stack of products may be in the pivoting device, e.g. in the gripper thereof. The gripper may be slightly open in particular for aeration. A straightening and/or unfanning device may comprise two vertical surfaces, for instance plates, preferably with lateral chamfers, that are movable relative to one another. This device may be open before the pivoting step and closed after the pivoting step. For this purpose, the surfaces may be moved towards and away from one another. Pneumatic cylinders may be provided to create the vibration. Finally the device/the surfaces thereof preferably move(s) into an open position so that the stack of products may be taken over. 
     A further development may be characterized in that in the vertical position, the stack of products is turned about a vertical axis, preferably by 180°. This advantageously allows the stack of products in the vertical position to be gripped from the same side both when it is selectively turned and when it is selectively not turned. The rotating may be done by the pivoting device. For this purpose, the pivoting device may have a rotary drive. The rotary drive may be controlled by a digital computer. 
     A further development may be characterized in that when the stack of products is turned, it is taken over from one side of the stack of products and when the stack of products is not turned, it is taken over from the same side of the stack of products. The takeover from the one side or from the other side may be carried out by an articulated arm of the robot. The selection of the side may be computer-controlled. In this process, a predefined deposit scheme may be taken into consideration. 
     A further development may be characterized in that the robot takes over the stack of products in the vertical position. For this purpose, the robot and in particular the gripper thereof may be moved towards the stack of products in a computer-controlled way, for instance from above and/or from one side. 
     A further development may be characterized in that the stack of products is moved in the vertical position, at least in a path section of the movement. The position of the stack of products may be changed along the path of the movement, for instance by pivoting it (about a horizontal axis) and/or by rotating it (about a vertical axis). 
     A further development may be characterized in that the robot takes over the stack of products from the pivoting device and then moves it. The stack of products may be taken over and held by a gripping device of the robot. The movement may be effected by moving an articulated arm of the robot. The robot may additionally be displaced in a horizontal direction. All actions of the robot may preferably be computer-controlled. 
     A further development may be characterized in that when the stack is turned, it is taken over from one side of the stack of products and when the stack is not turned, it is taken over from the opposite side of the stack of products. The takeover from the one side or from the other side may be carried out by an articulated arm of the robot. In this process, a gripping device of the robot may be rotated in such a way that a gripping action occurs from the one side or from the other side. The selection of the side may be computer-controlled. In this process, a predefined deposit scheme may be taken into consideration. 
     A further development may be characterized in that the pivoting through the effective angle α 2  occurs during the movement or in between two movement portions or after the movement. The pivoting movement may be computer-controlled. In this process, a predefined deposit scheme may be taken into consideration. 
     A further development may be characterized in that the pivoting through the effective angle α 2  is done using the robot. The pivoting movement may be achieved by a corresponding movement of an articulated arm of the robot and/or by a pivoting device on the robot/on the articulated arm thereof and/or by a pivotable gripping device on the robot/the articulated arm thereof. The pivoting movement may be computer-controlled. 
     A further development may be characterized in that as the stack of products is pivoted through the effective angle α 2 , it is pivoted back into a horizontal position. In this case, the stack of products is not turned, i.e. it is deposited unturned. 
     A further development may be characterized in that the stack of products is deposited in the horizontal position. The stack is preferably deposited on a pallet. To deposit the stack, grippers on the robot may simultaneously or successively be opened and moved away laterally. 
     A further development may be characterized in that before the stack of products is deposited, it is rotated about a vertical axis. This allows the alignment of the stack of products in the horizontal to be modified, for instance effectively by 90° or 180°. The rotation may be computer-controlled. In this process, a predefined deposit scheme may be taken into consideration. 
     A further development may be characterized in that the effective angle α 1  equals 90° and the effective angle α 2  equals 90° and in that the stack is pivoted further through α 2 . When the stack is pivoted further, the pivoting movement through al and the pivoting movement through α 2  preferably occur in the same pivoting direction. In this process, the total effect is that the stack of products is turned. 
     A further development may be characterized in that the effective angle α 1  equals 90° and the effective angle α 2  equals −90° and that the stack is pivoted back through α 2 . When the stack is pivoted back, the pivoting movement through al and the pivoting movement through α 2  preferably occur in opposite pivoting directions. In this process, the total effect is that the stack of products is not turned. 
     A further development may be characterized in that the stack of products is held by at least two grippers during the movement. 
     A further development may be characterized in that the stack of products is held in a form-fitting/positive and/or force-fitting/non-positive way during the movement. 
     A further development may be characterized in that one side of the stack of products has at least four corners and in that the stack of products is held at diagonally opposite corners during the movement. If there are more than four corners, edges may be selected that are spaced apart by a large distance and/or are spaced apart in a way that is a good approximation to being diagonally opposite each other. 
     A further development may be characterized in that selectively, two diagonally opposite corners or two other diagonally opposite corners may be held. The selection of the corners may be computer-controlled. In this process, a predefined deposit scheme may be taken into consideration. For this purpose, a gripping device on the robot arm is preferably rotated. 
     A further development may be characterized in that the stack of products is held in such a way that the stack of products sags. For this purpose, the distance between grippers of the robot may be reduced preferably in a computer-controlled way until a desired or predefined sag is attained. The stack of products may be formed of folded paper sheets. 
     A further development may be characterized in that the stack of products is held in such a way that the stack of products sags diagonally. In this way, the stack of products with the diagonal as its “lowest point” may be deposited in a controlled and self-fixing way. For this purpose, the stack of products may be held on diagonally opposite corners. 
     Special Further Developments Pertaining to Stack Deposition 
     The following paragraphs describe preferred further developments of the invention (in short: further developments). 
     A further development may be characterized in that the movement terminates at a selected deposit position among multiple deposit positions of a predefined deposit scheme. The deposit scheme may be saved on a digital computer or on a network connected thereto. A plurality of deposit schemes may be saved, for instance in a database. The selection of the deposit position (and/or a sequence of deposit positions for stack of products to be moved in succession) may be computer-controlled. When a transport stack is built up out of stacks of products, a deposit scheme may be selected for every horizontal layer, in particular different deposit schemes may be selected for two successive layers. 
     A further development may be characterized in that the stack of products is deposited at the selected deposit position on a base, preferably a pallet. 
     A further development may be characterized in that the stack of products is held in such a way that it sags in the diagonal and in that when the diagonally-sagging stack of products is deposited, the sagging portion is the first to touch the base. 
     A further development may be characterized in that the deposit scheme is saved on a digital computer or uploaded onto the digital computer from another digital computer via a network and in that the movement is controlled by the digital computer. 
     A further development may be characterized in that the deposit scheme is calculated and/or selected by the digital computer as a function of at least one of the following parameters: dimensions of the stack of products; dimensions of the base; in a case in which the stack of products is a stack of folded products: position of the folding edges relative to the base and/or structure of the folding edges as a function of the type of fold. 
     A further development may be characterized in that multiple stacks of products are successively moved, selectively turned, selectively rotated in the horizontal, and deposited at respective selected deposit positions among multiple deposit positions of the predefined deposit scheme. In this process, a computer-controlled robot with an articulated arm and a gripping device may be used. 
     Special Further Developments Pertaining to the Gripping Operation 
     The following paragraphs describe preferred further developments of the invention (in short: further developments). 
     A further development may be characterized in that two grippers are used and in that when the stack of products is deposited, the grippers are moved away from the stack of products in the horizontal in two directions perpendicular to one another. 
     A further development may be characterized in that when the stack of products is deposited, the grippers open in the vertical. In this process, a gripper jaw of the gripper may be moved; preferably, a gripper jaw located above the stack of products may be moved upward. The other gripper jaw, preferably the one underneath the stack of products, may be unmoved. 
     A further development may be characterized in that every stack of products is moved to a respective deposit position of the deposit scheme, the respective deposit position selected in such a way that in the deposit position, the grippers are removed from the stack of products in the horizontal and without collision with stacks of products that have already been deposited. 
     Further Developments 
     The following paragraphs describe preferred further developments of the invention (in short: further developments). 
     A further development may be characterized in that the movement of the stack of products occurs from a delivery of a machine for the further processing of printed products to a pallet or to one of several pallets. In the latter case, non-stop operation is possible. 
     A further development may be characterized in that the movement of the stack of products occurs from a delivery of a machine for the further processing of printed products, for instance a folder, a saddle stitcher, or a perfect binder, to a pallet or to one of several pallets. 
     A further development may be characterized in that the stacks of products are transported in a direction of transport in the delivery and are separated from one another in the direction of transport. The transport may occur on a roller-type conveyor. For the separation, individual drivable rollers may be driven or stopped in an appropriate way. 
     A further development may be characterized in that the robot is movable and usable at multiple positions of a machine for further processing or at multiple machines for further processing. For this purpose, the robot may be supported on rollers and/or rails. 
     A further development may be characterized in that the stack of products is formed of folded and/or die-cut printed products. 
     A further development may be characterized in that multiple stacks of products are stacked on top of one another to be horizontally offset relative to one another and in multiple horizontal planes above one another to form a transport stack on a transport pallet or in that a transport stack is formed or built up in a corresponding way. The selection of the offset and/or of the planes may be computer-controlled. In this process, a predefined deposit scheme may be taken into consideration. 
     A further development may be characterized in that a sensor disposed on the robot detects the height of the transport stack. The sensor may be disposed on a gripping device of the robot. Multiple sensors may be provided. The height may be determined in absolute terms, for instance measured from the upper edge of a pallet or floor, or in relative terms as a distance to the sensor. 
     A further development may be characterized in that the height is detected as a single height value, as a number of height values at various horizontal positions, or as a height profile. 
     A further development may be characterized in that as the sensor, a distance sensor for measuring the height is used or in that a camera with digital image processing to calculate the height on the basis of the camera image is used. 
     A further development may be characterized in that the robot arm is moved without collision over a transport stack that has only partly been built up and in that the digital computer factors in the detected height as it controls the movement of the robot arm. 
     A further development may be characterized in that the robot takes individual intermediate layers off of a stack and deposits them on respective planes. The intermediate layers may be made of cardboard. The deposit of intermediate layers may be computer-controlled. In this process, a predefined deposit scheme and/or stacking scheme may be taken into consideration. 
     A further development may be characterized in that the intermediate layer is held by suction. For this purpose, a suction gripper may be disposed on a gripping device of the robot. A number of such suction grippers may be used. 
     A further development may be characterized in that the movement is done in a fully automated way, as a function of a selected deposit scheme and/or stacking scheme and in a way adapted to the production speed of the at least one machine for further processing. 
     A further development may be characterized in that the movement of the robot arm occurs in a protected area. 
     A further development may be characterized in that to create the protected area, a housing and/or a fence and/or a light barrier and/or a monitoring camera is used. 
     Special Further Developments Pertaining to a Device for Implementing the Method 
     The following paragraphs describe preferred further developments of the invention (in short: further developments). 
     A further development of the method of the invention may be characterized by the use of a device with a robot for moving a stack of products, the robot containing an articulated arm and a first gripper for the stack of products disposed on the articulated arm. The method is characterized in that a gripping device containing the first gripper and a second gripper is disposed on the articulated arm, the first gripper and the second gripper being positioned relative to one another. 
     The aforementioned device as such may represent a further invention. 
     A device for moving a stack of products with a robot, the robot containing an articulated arm and a first gripper for the stack of products disposed on the articulated arm. The device is characterized in that a gripping device comprising the first gripper and a second gripper is disposed on the articulated arm, the first gripper and the second gripper being positionable relative to one another. 
     The device as such or the use thereof advantageously provides a way of moving stacks of products in an automated way, in particular to deposit them in a turned or unturned arrangement. 
     A particular advantage may be considered to be that stacks of products of different sizes or formats may be moved and in particular selectively deposited in a turned or unturned arrangement. 
     The following paragraphs describe preferred further developments of the invention (in short: further developments). These further developments may also represent preferred further developments of the further invention, i.e. the device as such. 
     A further development may be characterized in that the two grippers are positionable, preferably in a computer-controlled way, to accommodate predefined formats of products or stacks of products. The grippers may be movable, preferably linearly movable, for positioning purposes. The positioning is preferably computer-controlled. 
     A further development may be characterized in that the two grippers are positionable on the two ends of a selected diagonal of a selected format. The positioning is preferably computer-controlled. 
     A further development may be characterized in that the first gripper is configured as a first pliers-type gripper with a first pair of gripper jaws and the second gripper is designed as a second pliers-type gripper with a second pair of gripper jaws. 
     A further development may be characterized in that each one of the two pairs of gripper jaws contains an immobile gripper jaw and a mobile gripper jaw that is linearly movable relative to the immobile gripper jaw. Linear drives may be provided, preferably electric linear drives with threaded spindles. Of course, the immobile gripper jaws are not totally immobile: they may be moved by the motion of the robot, of the gripping device and/or of the grippers. The immobile gripper jaws are only unmoved or only negligibly moved relative to the movable gripper jaws when the grippers open and close. 
     A further development may be characterized in that each one of the immobile gripper jaws comprises a support element extending in a horizontal direction and at least one stop element extending in a vertical direction. 
     A further development may be characterized in that each one of the immobile gripper jaws contains a support pad extending in a horizontal direction as the support element and two stop surfaces extending in a vertical direction and perpendicular to one another as stop elements. All surfaces may be perpendicular to one another. 
     A further development may be characterized in that the stack of products is held in a form-fitting/positive and/or friction-fitting/non-positive way during the movement. 
     A further development may be characterized in that at least one blower device is disposed on the gripping device to blow air under the stack of products when the stack of products is deposited. 
     A further development may be characterized in that at least one further gripper is disposed on the gripping device, the further gripper designed as a suction gripper for intermediate layers. For suction-based gripping and holding, suction air may be applied to the suction gripper in a computer-controlled way. 
     A further development may be characterized in that at least one distance sensor and/or at least one camera is provided on the gripping device. 
     A further development may be characterized in that the gripping device contains a first support arm on which the first gripper is disposed for linear movement in the longitudinal direction of the first support arm. 
     A further development may be characterized in that the gripping device contains a second support arm on which the second gripper is disposed for linear movement in the longitudinal direction of the second support arm. 
     A linear drive, preferably an electric linear drive with a threaded spindle, may be provided on the support arm to move the grippers along the support arms. The linear drive may be electric. The support arm may have a length correlating with a maximum-format stack of products to be moved. 
     A further development may be characterized in that the first support arm and the second support arm are disposed on the gripping device so as to be perpendicular to one another. The support arms may form an X-Y axis system for format-adjustable grippers. Movable gripper jaws of the grippers may form the Z axis that is perpendicular thereto. 
     A further development may be characterized in that the two linearly movable gripper jaws are movable in a direction perpendicular to the respective support arm. 
     A further development may be characterized in that the gripping device is disposed on the robot arm so as to be rotatable about an axis of rotation. The axis of rotation is preferably for rotating the stack of products about a vertical axis and/or for depositing a stack of products that has been rotated in the horizontal. 
     A further development may be characterized in that the gripping device is disposed on the robot arm so as to be pivotable about a pivot axis perpendicular to the axis of rotation. The pivot axis is preferably for pivoting the stack of products about a horizontal axis and/or for depositing a stack of products that has selectively been turned or not turned relative to the horizontal. 
     A further development may be characterized in that the articulated arm has six axes, preferably axes of rotation. 
     A further development may be characterized in that the robot is horizontally displaceable, for instance on rails or rollers, relative to one or more machines for further processing that create stacks of products. 
     In any desired combination with one another, the features and combinations of features described in the above sections Technical Field, Invention, and in the various sections above on further developments as well as in the following section Exemplary Embodiments represent further advantageous further developments of the invention. 
     As an alternative to the aforementioned 2-step pivoting process, the object may be attained by a single-step pivoting process. In this process, for selective turning, the stack of products in horizontal alignment is preferably gripped from below by the gripping device of an articulated robot and pivoted through an effective angle of 180°, for instance while it is being moved to the pallet. When the stack is not to be turned, the stack of products in horizontal alignment may preferably be gripped from above. 
     Other features which are considered as characteristic for the invention are set forth in the appended claims. 
     Although the invention is illustrated and described herein as embodied in a method of moving a stack of products by means of a robot, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims. 
     The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
         FIG.  1    is an illustration of a preferred exemplary embodiment of a device containing a robot for carrying out steps of a preferred embodiment of a method according to the invention; 
         FIG.  2    is a perspective view of a delivery of a machine for further processing; 
         FIGS.  3 A and  3 B  are perspective views of preferred exemplary embodiments of the delivery; 
         FIGS.  4 A to  4 D  are perspective views of preferred exemplary embodiments of a robot-guided gripping device; 
         FIG.  5    is a perspective view of a preferred exemplary embodiment of the gripping device; 
         FIGS.  6 A and  6 B  illustrate preferred exemplary embodiments of deposit schemes; 
         FIG.  7    is a lateral view of a preferred exemplary embodiment of a transport stack; and 
         FIG.  8    is a flow chart for illustrating a method for moving a stack of products by means of a robot. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In the drawings, corresponding features have the same reference symbols. Repetitive reference symbols have sometimes been left out for reasons of visibility. The following is a summary list of reference numerals and the corresponding structure used in the above description of the invention. 
     Referring now to the figures of the drawings in detail and first, particularly to  FIG.  1    thereof, there is shown a preferred exemplary embodiment of a device preferably containing a robot and carrying out steps of a preferred embodiment of the method of the invention.  FIG.  1    is a view from above. 
     A machine  70  for further processing, preferably a folder, which is only partly shown, is located in a position  74  and produces printed products  2 , preferably printed and/or folded signatures  2 , which are in the form of stacks  1  of products and are moved, e.g. conveyed, in a direction of transport  71  on a delivery  72 . The action of the delivery, in particular the conveying action, may be controlled by a digital computer  80 . A stack of products preferably contains a plurality of products resting on top of one another. 
     The digital computer  80 , which is preferably connected to a network  81 , may control the machine  70  for further processing and optionally further machinery; for instance, it may provide job data for the manufacturing of products. Job data may be provided via the network. 
     The delivery  72  may move the stacks  1  of products into a protected zone  73 . A robot  10 , preferably a robot containing an articulated arm  11  with multiple axes  12 , for instance six axes, may be disposed in this zone. The robot may be a common industrial robot. 
     A gripping device  20  is disposed on the robot  10 , preferably at the end of the articulated arm/“hand”  11  thereof. The gripping device may grip and hold stacks  1  of products to move them away from the delivery  72 , preferably only within the protected zone. The movement  15  moves the stack  1  of products along a spatial curve to a transport pallet  62 , where the stack of products is deposited and preferably positioned at a deposit location  60  in accordance with a deposit scheme  61 . A number of pallets may preferably be provided within reach of the robot. The movement may comprise multiple movement portions  16 . In between two movement portions, the gripping device may be rotated and/or pivoted, for instance. The rotating and/or pivoting may likewise occur during the movement. 
     A pivoting device  40  is preferably disposed at the end of the delivery  72 . The pivoting device  40  may pivot the stacks  1  of products out of the horizontal  50 , horizontal plane  53  or the horizontal position  52  into the vertical  54 , the vertical plane  57  or the vertical position  56 , respectively. The pivoting device may comprise two alignment elements  41 , which are preferably movable in a horizontal direction, and/or straightening elements  42  for the stack of products. They may be embodied as surfaces, for instance plates. 
     The action, in particular the movement  15  and/or  16  of the robot  10 , and/or the action, in particular the pivoting, of the pivoting device may be controlled by the digital computer  80 . 
       FIG.  2    illustrates a preferred exemplary embodiment of a delivery of a machine for further processing. The delivery  72  may contain a plurality of rollers  76 . The delivery may be a roller conveyor. Some of the rollers may be driven, for instance by motors  75 . The digital computer  80  may control the process of conveying the stacks  1  of products  2  resting on top of one another. In this process, the stacks of products may be separated from one another in the direction of transport  71 . The products  2  and therefore also the stacks  1  of products that have been formed preferably have four corners  5 . Die-cut products may have more corners. If the products are folded products, their folding spines are preferably oriented to be parallel to the direction of transport. 
       FIGS.  3 A and  3 B  illustrate preferred exemplary embodiments of the delivery, preferably containing the pivoting device, as they carry out steps of a preferred embodiment of the method of the invention.  FIGS.  3 A and  3 B  are perspective views. 
       FIGS.  3 A and  3 B  illustrate the end of the folder  70  and the delivery  72  on which the stacks  1  of products are conveyed in the direction  71  of transport up to a pivoting device  40  (transporting step  101 ). Before being pivoted, the stacks of products and consequently the products  2  are preferably in a horizontal position  52 . 
     The pivoting device  40  preferably contains grippers  43 , for instance bars movable relative to one another, preferably one bar (closing “hold-down element”) on one side of the stack  1  of products and three bars on the other side of the latter. The pivoting device and/or the grippers thereof may be pivoted about a horizontal axis  51 . The grippers, which are located below the stack  1  of products in  FIG.  3 A , may be positioned between the rollers  76  and may be pivoted out of this position. 
       FIGS.  3 A and  3 B  illustrate sections of the robot  10  and the articulated arm  11  thereof. The robot is preferably movable in a horizontal direction on the floor and therefore positionable at various locations. The robot may, for instance, be supported on rollers. For example, rails may be provided. 
       FIGS.  3 A and  3 B  illustrate the—preferably horizontally movable—alignment elements  41  and/or straightening elements  42 . 
     A comparison between  FIGS.  3 A and  3 B  illustrates the pivoting movement/pivoting  110  through an effective angle α 1  (pivoting step  110 ). In the illustrated example, the angle α 1  is preferably 90°. After the pivoting step, the stack  1  of products is preferably in a vertical position  56 . If the products  2  are folded products, in the vertical position, the spines are preferably at the top. 
       FIGS.  3 A and  3 B  illustrate two sides  3  and  4 . The robot  10  may preferably grip the pivoted stack  1  of products from side  3  or from opposite side  4 . Side  3  may be referred to as the front side and side  4  as the back side. The selection of the side may be computer-controlled as a function of a deposit scheme. 
     The pivoting device may optionally be configured for rotation and may thus be rotated about a vertical axis  55 . The stack of products may preferably be rotated through 180°. In accordance with this option, the robot  10  may always grip the pivoted stack  1  of products from the same side, preferably from side  3 /the front side. 
       FIGS.  4 A to  4 D  illustrate preferred exemplary embodiments of a robot-guided gripping device as it carries out steps of a preferred embodiment of the method of the invention. The figures are perspective views. 
       FIGS.  4 A to  4 D  illustrate a flange  26  of the robot  10 . A gripping device  20  for stacks  1  of products is preferably disposed on the flange. The gripping device is preferably disposed for rotation about an axis of rotation  13  (rotating step  142 ). The gripping device is pivotable about a pivoting axis  14  (further pivoting step  122  or back pivoting step  123 ). Both the axis of rotation and the pivoting axis may be a respective single axis  12  of the robot or respective multiple axes. 
     The gripping device  20  preferably contains two support arms: a first support arm  21  and a second support arm  23 . The support arms are preferably perpendicular to one another. A first gripper  30  is preferably disposed on the first support arm so as to be movable in a first longitudinal direction  22 . A second gripper  32  is preferably disposed on the second arm so as to be movable in a second longitudinal direction  24 . The grippers may be driven by linear drives  25  to be adjusted as a function of the format. 
     The first gripper  30  preferably contains a first pair of gripper jaws  31  including an immobile gripper jaw  31   a  and a movable gripper jaw  31   b . The movable gripper jaw may be driven by a linear drive  37 . The second gripper  32  preferably contains a second pair of gripper jaws  33  including an immobile gripper jaw  33   a  and a movable gripper jaw  33   b . The movable gripper jaw may be driven by a linear drive  37 . Each one of the immobile gripper jaws may include a support element  34 , preferably a support surface. The movable gripper jaws act to open and close the grippers. 
     The grippers  30  and a  32  grip the stack  1  of products  2  preferably at the corners  5  thereof and especially at corners  6  that are diagonally opposite one another (see diagonal  7  in  FIG.  5   ). 
     In the example illustrated in  FIG.  4 A , the gripping device  20  grips the stack  1  of products that has been pivoted into a vertical position from side  4 , i.e. from the back side, for instance. In other words, when the gripping device grips the stack of products, it is preferably located on side  4 . To illustrate this, the transport direction  71  is indicated. 
     In the example illustrated in  FIG.  4 B , the gripping device  20  likewise grips the stack  1  of products that has been pivoted into a vertical position from side  4 , i.e. from the back side, for instance. 
     A comparison between  FIGS.  4 A and  4 B  shows that either the first pair of corners  5  (top left and bottom right) or the other pair of corners  5  (bottom left and top right) may be gripped. The edges may be selected in a computer-controlled way and as a function of a deposit scheme. 
     In the example shown in  FIG.  4 C , the gripping device  20  grips the stack  1  of products that has been pivoted into the vertical from side  3 , i.e. from the front side, for instance. 
     In the example shown in  FIG.  4 D , the gripping device  20  grips the stack  1  of products that has been pivoted into the vertical from side  3 , i.e. from the front side, for instance. 
     A comparison between  FIGS.  4 C and  4 D  in turn shows that either the one pair of corners  5  (“top left” and “bottom right”) or the other pair of corners  5  (“bottom left” and “top right”) may be gripped. The edges may again be selected in a computer-controlled way and as a function of a deposit scheme. 
     The decision whether the stack  1  of products is gripped from side  3  or from side  4  and whether the one pair of corners  5  or the other pair of corners  5  is gripped in this process depends on how the stack of products is to be deposited—whether it is to be deposited in a turned or unturned arrangement and whether it is to be deposited in a rotated or unrotated arrangement. This in turn depends on a selected deposit scheme and the respective deposit position within this scheme. The digital computer  80  controls the gripping operation and the appropriate action of the robot  10  in accordance with the deposit scheme and deposit position. In this process, the side and the corners are selected accordingly. 
     Having been gripped and during the movement  130 , in particular in between two movement portions  130   a  and  130   b  and preferably before being deposited (step  152 ), the stack  1  of products is pivoted through effective angle α 2 —either pivoted further (step  122 ) or pivoted back (step  123 ). When it is pivoted further, the stack of products is preferably deposited in a turned arrangement (turning step  140 ); when it is pivoted back, it is deposited in an unturned arrangement (non-turning step  141 ). 
       FIG.  5    illustrates a preferred exemplary embodiment of the gripping device as it carries out step  150  of letting a stack of products sag in accordance with a preferred embodiment of the method of the invention.  FIG.  5    is a perspective view. 
       FIG.  5    shows the gripping device  20  with the two grippers  30  and  32 . The grippers hold a stack  1  of products at diagonally opposite corners  6 . The grippers are positioned/spaced apart from one another on the two support arms  21  and  23  as a function of the format of the stack of products and in such a way that the stack of products sags (step  150  of letting the stack sag). When the stack of products is deposited on the transport pallet  62  or on a transport stack  64  that has already been formed, the sagging diagonal  8  touches the pallet/the transport stack first. This allows the stack of products to be deposited in a precise way without disturbance and the open grippers  30  and  32  to be moved away from the stack of products by moving them in directions  58  perpendicular to one another. The digital computer  80  may control the opening and moving away. 
       FIG.  5    illustrates the two immobile gripper jaws  31   a  and  33   a  with two respective stop elements  35 , in particular stop surfaces  35 . When the stack  1  of products is deposited, the two support elements  34  (disposed below the stack of products and therefore not visible in  FIG.  5   ) are preferably oriented in a horizontal direction, whereas the two respective (i.e. four) stop elements are preferably oriented in a vertical direction. The opening and closing of the grippers/the movement of the movable gripper jaws  31   b  and  33   b  occurs in a direction  38 . 
       FIG.  5    illustrates a sensor  66 , preferably disposed on one of the immobile (“lower”) gripper jaws  31   a  or  33   a . The sensor may measure the distance to the pallet or to the transport stack that has already been formed or the height  65  and may transmit the measured value to the digital computer  80 , allowing the latter to control a precise and in particular collision-free deposit. 
       FIG.  5    illustrates two further grippers  36 , in particular suction gripper  36 . They are preferably used to grip and hold intermediate layers  67 . 
       FIGS.  6 A and  6 B  illustrate preferred exemplary embodiments of deposit schemes. 
       FIGS.  6 A and  6 B  are top views of an example of twelve stacks  1  of products. They were deposited in an order from stack  1  to stack  12 . 
     At a respective corner of every stack of products, the gripping device  20  and flange  26  are shown as a circle. At two respective corners, the two grippers  30  and  32  are shown. Each one of arrows  58  indicates the directions into which the opened grippers are moved to release the stack of products. 
     Depositing the stacks  1  of products at the deposit positions  60  in accordance with the respective selected deposit scheme  61  allows the grippers  30  and  32  to move in the horizontal without colliding with stacks of products that have already been deposited before. 
     As shown in  FIGS.  6 A and  6 B , what is referred to as a “chimney”  68 , an empty space in the deposit scheme, may be created. 
     A comparison between  FIGS.  6 A and  6 B  shows that the deposit scheme may change. The deposit scheme is preferably changed in every new horizontal plane/layer of a transport stack to be formed. This improves the stability of the transport stack. 
       FIG.  7    illustrates a preferred exemplary embodiment of a transport stack created by the steps of “depositing”.  FIG.  7    is a lateral view. 
     A first layer  63  of stacks  1  of products has been deposited on a transport pallet  62  in accordance with a first deposit scheme. On top of it, an intermediate layer  67  has been deposited. The robot may take intermediate layers off a neighboring stack of intermediate layers. Suction grippers  36  may be used for this purpose. A second layer  63  of stacks  1  of products is deposited on the intermediate layer in accordance with the second deposit scheme, which is preferably different from the first deposit scheme. As it can be seen, the edges of the stacks  1  of products may have a horizontal offset  69  relative to one another. This improves the stability of the transport stack. 
     As the gripping device  20  approaches the transport stack  64 , the sensor  66  may measure the vertical distance  65  and the digital computer  80  may use the measured value to control the collision-free movement of the gripping device. 
       FIG.  8    illustrates a preferred exemplary embodiment of a flow chart. Optional steps are indicated by dashed lines. 
     The processing step ( 100 ) may comprise the manufacturing of folded products  2 . 
     The transporting step ( 101 ) may comprise the transportation of stacks  1  of products into a direction of transport  71 . 
     The separating step ( 102 ) may comprise the separation of stacks  1  of products in the direction of transport  71 . 
     The stopping step ( 103 ) may comprise the stopping of the stack  1  of products at a pivoting device  40 . 
     The pivoting step ( 110 ) may comprise a pivoting of the stack  1  of products  1  by means of a pivoting device  40 , in particular through an angle α 1 =90°. 
     The aligning step ( 111 ) may comprise an alignment of the stack of products, preferably about a vertical axis. Alignment elements  41  may be used for this purpose. 
     The step of straightening ( 112 ) may comprise a straightening of the products  2 . A straightening element  42  may be used for this purpose. 
     The vibrating step ( 113 ) may comprise a vibration of the stack  1  and consequently of the products  2 . 
     The aerating step ( 114 ) may comprise an aeration of the stack  1  of products. The aeration may be attained by the vibration. 
     The modifying step ( 115 ) may transform a fanned-out stack of products  1  into an unfanned stack of products. Alignment elements  41  may be used for this purpose. Each one of them may be formed by a surface such as a plate with two chamfers. 
     The takeover step ( 120 ) may be done by the gripping device  20  and in particular the grippers  30  and  32  thereof. In the takeover, the stack of products may be transferred from the pivoting device  40  to the gripping device  20 . The takeover may occur from side  3  or from side  4 . 
     The holding step ( 121 ) may be done by the closed grippers  30  and  32 . 
     The forward pivoting step ( 122 ) may be done by the robot arm  11 , in particular through α 2 =90°. 
     The back pivoting step ( 123 ) may be done by the robot arm  11 , in particular through α 2 =−90°. Further pivoting or back pivoting are preferably selected as a function of the deposit scheme. 
     The moving step/movement ( 130 ) is preferably done using the robot  10 . 
     The partial moving step/movement portion ( 130   a ) and the partial moving/movement portion ( 130   b ) are preferably done using the robot  10 . 
     The calculating step ( 131 ) is preferably done using the digital computer  80 . The movement of the robot  10  may be calculated. 
     The controlling step ( 132 ) is preferably done using the digital computer  80 . The movement of the robot  10  may be calculated. 
     The turning step ( 140 ) may be done by the robot arm  11 , in particular through α 1 +α 2 =180°. 
     The non-turning step ( 141 ) may be done by the robot arm  11 , in particular through α 1 +α 2 =0°. 
     The rotating step ( 142 ) may be done by the robot arm  11 . 
     The step of letting sag ( 150 ) may be attained due to an adjustable distance between the two grippers  30  and  32 . 
     The measuring step ( 151 ) of measuring the distance  65  and/or height  65  may be done by the sensor  66 . 
     The depositing/stacking step ( 152 ) may be done by the robot arm  11 . In this process, a predefined deposit scheme  61  may in particular be taken into consideration. 
     The following is a list of reference numerals and symbols appearing in the foregoing description with reference to the figures of the drawing:
       1  stack of products     2  printed products, in particular folded printed products     3  side     4  opposite side     5  corners     6  diagonally opposite corners     7  diagonal     8  sagging diagonal     10  device, in particular robot     11  robot arm/articulated arm     12  axes     13  axis of rotation     14  pivot axis     15  movement/path     16  part of movement/part of path     20  gripping device     21  first support arm     22  first longitudinal direction     23  second support arm     24  second longitudinal direction     25  linear drive     26  flange     30  first gripper, in particular pliers-type gripper     31  first pair of gripper jaws     31   a  immobile gripper jaw     31   b  mobile gripper jaw     32  second gripper, in particular pliers-type gripper     33  second pair of gripper jaws     33   a  immobile gripper jaw     33   b  mobile gripper jaw     34  support element, in particular support pad     35  stop elements, in particular two stop surfaces     36  further gripper, in particular suction gripper     37  linear drive     38  movement to open/close the grippers     39  blower device     40  pivoting device     41  alignment elements     42  straightening element     43  gripper     50  horizontal     51  horizontal axis     52  horizontal position     53  horizontal plane     54  vertical     55  vertical axis     56  vertical position     57  vertical plane     58  two directions perpendicular to one another     60  deposit position     61  deposit scheme     62  base, in particular pallet     63  position of already deposited stacks of products     64  transport stack     65  height     66  sensor, in particular distance sensor or camera     67  intermediate layer     68  chimney     69  offset     70  machine for further processing, in particular folder     71  direction of transport     72  delivery     73  protected zone     74  position of a machine for further processing     75  drives     76  rollers     80  digital computer     81  network     100  processing step     101  transporting step     102  separating step     103  stopping step     110  pivoting step     111  aligning step     112  straightening step     113  vibrating step     114  aerating step     115  changing step     120  takeover step     121  holding step     122  step of further pivoting     123  step pivoting back     130  moving step/movement     130   a  partly moving step/movement portion     130   b  partly moving step/movement portion     131  calculating step     132  controlling step     140  turning step     141  step of not turning     142  rotating step     150  step of letting sag     151  measuring step     152  depositing/stacking step   α 1  (first) effective angle   α 2  (second) effective angle