Abstract:
The invention relates to a method and device for transporting and rotating sheet-form print material. A rotation unit carried on a transport unit is moveable along a carriage guide. A gripper on the rotation unit holds the sheet form print material. Mechanical interaction between the rotation unit and the carriage guide causes the gripper to rotate.

Description:
The invention relates to a method and device for transporting and rotating sheet-form print material. 
   Typically, devices of the type named are used in a print further-processing device to move stacks of sheet-form print materials that will be bound, or are already bound, from one processing station to the next or to stack them in a storage unit. What is important is that the sheet-form print materials in the stack do not lose their alignment to each other, since otherwise errors would occur during, for example, the outside edge processing of the stack of sheet-form print materials. Another error that could otherwise occur is that punched holes, e.g. for a wire comb binding, plastic comb binding or spiral binding can slip, which leads to later problems when threading through a corresponding binding element. 
   In these cases, the rotation of a stack of sheet-form print materials is usually especially complicated since the stack of sheet-form print materials is exposed to torques that necessitate adequately protecting the individual sheet-form print materials against slipping. In addition, turning and transporting of stacks of sheet-form print materials generally require a relatively large amount of space; for a combined movement, the space requirement increases even more. 
   A number of devices for transporting and rotating books in sheets are known from the prior art. European Patent Application EP 1 122 198 A2 shows e.g. a turning device for books in sheets. In this process, a book in sheets is transported between two endless transport belts that are mounted on a turning unit. As soon as the book in sheets is located completely between the two endless transport belts, the book in sheets is fastened in this position, the entire turning device is rotated 180°, the book in sheets is released again and transported further. However, the device shown there is not very suitable for unbound stacks of sheet-form print materials since the book in sheets must first ascend a slope between two transport bands. In this case, the axis of rotation is parallel to one of the outside edges of the book in sheet&#39;s pages. 
   The German OLS DE 36 08 870 A1 shows another conveyor device in which stacks of sheet-form print materials that are securely fastened to holding elements are turned 180°. The force of the rotation is provided to the device from a lifting roller that can optionally be connected to a fixed curved rail and be fastened at the axis of rotation via a lever. The axis of rotation is normal to the plane of the sheet-form print materials and has a slight deviation from the vertical. 
   In further processing devices having the most compact construction possible, the spatial requirement and energy requirement of the individual components play a critical role. A transport device for stacks of sheet-form print materials or books in sheets takes up a lot of space within the system. The space cannot be used by other units within the system, in order not to have conflicts between a stack of sheet-form print materials that is passing by and the transport device holding them unless there is a complicated synchronizing of the units that at times use the same space within the system. 
   During rotation of a stack of sheet-form printed materials, the required space for the transport/rotation unit considerably increases. The smallest spatial requirement is generally needed if the axis of rotation is normal to the surface of the sheet-form print materials and at a right angle to the transport device for the stack of sheet-form print materials. 
   SUMMARY OF THE INVENTION 
   According to various aspects of the invention, methods and devices are provided for transporting and rotating sheet-form print material. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  presents a schematic representation of a device according to one aspect of the invention. 
       FIG. 2  presents a schematic representation of a transport unit according to one aspect of the invention. 
       FIG. 3  presents a schematic representation of a rotation unit according to one aspect of the invention. 
       FIG. 4  presents a schematic representation showing a cam of the rotation unit according to one aspect of the invention. 
   

   DETAILED DESCRIPTION 
   Various aspects of the invention are presented in  FIGS. 1-4 , which are not drawn to any particular scale, and wherein like components in the numerous views are numbered alike. Referring now specifically to  FIG. 1 , a device  100  is presented, according to one aspect of the invention. Generally known drive and/or guiding means and cams implemented for operating the device  100  are shown only schematically and/or are only described in a general way, since suitable apparatus and methods are known in the relevant arts. The device  100  comprises a carriage guide  20 , on one side of which a drive  10  is mounted. Drive  10 , e.g. an electric motor, drives a pulley  14 . A belt  12  is held by the pulley  14  and a pulley  16  mounted at the other end of carriage guide  20 . A suitable transmission can also be connected between pulley  14  and drive  10 , depending on the performance characteristics of drive  10 . 
   The transport unit  30  is mounted on the carriage guide  20  so that it can move. A belt connection  34  (see  FIG. 2 ) is mounted on the endless belt  12  so that it cannot slip. Movement of the belt drive is transferred to movement of transport unit  30  along the carriage guide  20 . 
   The transport unit  30  holds a rotation unit  40 , presented in  FIG. 3. A  gripper  60  is mounted on the rotation unit  40 , which can tightly clamp a stack of sheet-form print materials  70 . The gripper  60  may be configured as tongs, for example. 
   Referring again to  FIG. 2 , the transport unit  30  moves, together with rotation unit  40  and gripper  60 , in the direction of the arrows identified with reference numbers  1 ,  2  along carriage guide  20  in a first transport direction  1  and/or second transport direction  2 . In this process, in the transport direction  1 , gripper  60  is loaded with a stack of sheet-form print materials  70  and unloaded in second transport direction  2 . 
     FIG. 2  shows transport unit  30  of device  100  according to an aspect of the invention. Frame  31  of transport unit  30  is made up of a number of rectangular hollow profiles, preferably manufactured of steel or aluminum, thereby leading to a greater stability of transport unit  30  with lighter construction. 
   On frame  31 , seven rollers  36  are mounted in ball bearings, preferably plastic injection-coated ball bearings with round running surfaces. Rollers  36  are each assigned to eccentrics (not shown) that are known to the person skilled in the art, by means of which the positions of rollers  36  are individually adjustable in order to compensate tolerances in manufacturing and installation and to ensure that rollers  36  roll within carriage guide  20  in a manner that is as free of friction as possible. 
   On frame  31  of the transport unit  30 , two stops  37 ,  38  are mounted for the limit positions of the rotary movement of gripper  60  and limit the movement of the gripper. The stops  37  and  38  are optional. In addition, positioning pins  33  having conical tips are mounted on frame  31  of transport unit  30  into which rotation unit  40  is inserted so that rotation unit  40  has a defined position with respect to transport unit  30 . The conical tips of the positioning pins  33  make installation of rotation unit  40  and transport unit  30  easier and ensure exact alignment between rotation unit  40  and transport unit  30 . 
     FIG. 3  shows rotation unit  40  in detail. A lever roller  41  that is mounted on a lever  42  with a ball bearing runs on guides  21  and  22 , and cam section  24 , as shown in FIG.  4 . The cam section  24  has two cam surfaces  25  and  26  and is intermediate opposing ends of the carriage guide  20 . Referring again to  FIG. 3 , lever  42  is connected to a first timing pulley  43 , around which a timing belt  44  runs. Timing belt  44  also runs around a second timing pulley  45 . In this process, timing belt  44  is pre-stressed by a belt tightener  52 . The ratio of the number of teeth in the first timing pulley  43  and the number of the teeth in the second timing pulley is 2 to 1. 
   The second timing pulley  45  runs on a shaft  46 , which can be coupled on the other side with a connection  47  on gripper  60 . For exact positioning between rotation unit  40  and gripper  60 , four pins  48  are used that extend into gripper  60 . 
   Rotation unit  40  has a frame  50  in which rotation unit  40  is connected to transport unit  30 . Rotation unit  40  also has guide pins  51  to ensure exact positioning between rotation unit  40  and transport unit  30 . 
   In addition, rotation unit  40  has a spring unit  49 . Since gripper  60  is preferably positioned exactly horizontally. The position of the gripper  60  is defined by the aforementioned stops  37 ,  38  on the transport unit. The stops  37 ,  38  and rotation unit  30 , especially lever roller  41  and guide  21  (FIG.  4 ), are dimensioned to provide a small interference with the guide  22  that forces the lever  42  to turn somewhat further upon installation so that the gripper  60  is tensioned against the stops  37 ,  38  and the lever roller  41  is tensioned against the guide  21 . In such manner, any looseness due to tolerances and/or expansions in the system is compensated for by the spring unit  49 . 
   At this point, in a first position of lever  42 , the function of spring unit  49  will be described using the guides  21 ,  22  and cam surfaces  25 ,  26  that lever roller  41  contacts. If transport unit  30  and rotation unit  40  are located on the other side of carriage guide  20  (the right side of FIG.  4 ), lever  42  is turned 91° relative to a beginning position on the opposite side of the carriage guide  20  (the left side of FIG.  4 ), and the roller  41  moves from a position below the guide  22  mounted below to above the guide  21 . Since in this case gripper  60  has turned, the tension relationships in belt  44  reverse and lever roller  41  is pressed from below (underneath) onto guide  22 , comparable to the first case described. In other words, the roller  41  is pressed onto curved section  21  from above, and onto guide  22  from underneath. 
     FIG. 4  shows the guides  21 ,  22 , and cam section  24  in detail. Guides  21  and  22  are straight and each have an exposed guide surface that the roller rides on. If transport unit  30 , together with rotation unit  40  and gripper  60 , are located on the right side of guide  21 , the lever is pre-stressed against guide  21  as described above. 
   During the movement in the first transport direction  1 , lever roller  41  is guided in the area of the cam section  24  along first cam surface  25  and in this process the lever  42  is swiveled 91°, which leads to a rotation of the gripper  60  by essentially 180°. As soon as gripper  60  is swiveled through the center, lever roller  41 , because of the changed weight ratios, contacts the second cam surface  26  in the area of the intermediate section  24 . Rotation of gripper  60  further than 180° is prevented by stops  37 ,  38  already mentioned above. Then lever roller  41  runs against the guide  22 . On the return path in second transport direction  2  (opposite to transport direction  1 ), the movement of lever roller  41 , and thus of gripper  60 , reverses. 
   If transport unit  30 , together with rotation unit  40  and gripper  60 , is located on the right side of guide  21  pictured in  FIG. 4 , the rotation unit can simply be taken out toward the top, for maintenance purposes, for example. 
   As shown in  FIG. 4 , the structure of cam surfaces  25  and  26  are asymmetrical in intermediate section  24 . First guide  25  has, in the first transport direction  1 , a lesser inclination than the second guide  26  in the second transport direction  2 . Because of this, the rotation of the loaded gripper  60  in the first transport direction  1  is started more gently than the rotation of the unloaded gripper  60  in second transport direction  2 . The more gentle handling of gripper  60  in the first transport direction  1  is taken into account in order to decrease the stress on loaded gripper  60  and thus decrease the risk of a slipping stack of sheet-form print materials. The braking of the loaded gripper is cushioned in the first transport direction  1  by the spring unit  49  so that, even during braking of the gripper  60 , there is no displacement of the individual sheet-form print material in the stack  70 . 
   Because of the concentration of the movement of gripper  60  within the intermediate section  24 , independent of the format of the stack of sheet-form print materials  70 , the gripper  60  can continuously be turned at the same location and without an additional drive for rotation of the gripper  60 . The entire turning movement is derived completely from drive  10  of transport unit  30 . 
   According to a preferred embodiment of the invention, the force needed to rotate the gripper that hold the stack of sheet-form materials is derived completely from translational transport movement along a cam. It is especially advantageous that the movement of the lever along with the lever roller may be transmitted by a set of gears. Because of this, the rotation of the gripper of essentially 180° can be achieved by a smaller rotation of the lever, which leads to a simpler structure, especially in the area of the cam. A significant advantage in the use of a set of gears for transmission of the curve movement is that the rotation of the gripper may be carried out at a different angular speed than that of the lever. Because of this, the rotation of the gripper can be accelerated considerably. In an advantageous manner, the transmission has the ratio of 1 to 2 between movement of rotation of the lever to rotation movement of the gripper. 
   In an advantageous embodiment according to an aspect of the invention, the rotation unit may be installed in the transport unit so that it can be detached. This is advantageous for maintenance work that may be needed, repairs or replacement of the rotation unit and also makes installation of the device according to the invention easier. Advantageously, the transport unit may have guiding elements onto which the rotation unit is installed so that the rotation unit has a defined position with respect to the transport unit. Because of this, an especially fast, precise and repeatable installation of the rotation unit in the transport unit may be possible. 
   In an especially advantageous embodiment according to an aspect of the invention, the cam has a short curved section on which the rotation unit completely executes a rotation of the gripper by essentially 180°. Because of this, the entire rotation of the gripper and, thus, of the stack of sheet-form print materials may be carried out at a specified location. 
   This may be advantageously in the center of the transport path of the stack of sheet-form print materials so that the rotating gripper have as much room as possible to carry out the rotation. At the same time, the space required for rotation is nevertheless concentrated in a small spatial area because of this measure according to the invention. Because of the concentration of the movement in a specific spatial area, the specification for a space requirement that is small overall, for one thing, can be addressed. For another thing, stacks of sheet-form print materials having all different dimensions that are provided for use with the device according to the invention can be rotated uniformly at the same location without significant fluctuations resulting in the spatial area of the stack of sheet-form print materials. The space provided for executing the rotation of the stack of sheet-form print materials, and the rotation of the gripper connected with it, specifies the maximum dimensions of the sheet-form printed materials that can be used with the device according to the invention. 
   Advantageously, the cam section may be optimized with respect to the moments of inertia of the gripper. The gripper, or a different clamping device for a stack of sheet-form print materials, may be located in a loaded condition, in which at least the rotation but possibly also the transport of the stack of sheet-form print materials from a first position to a second position takes place within a higher level device. Otherwise, the gripper or another clamping device for a stack of sheet-form print materials are in an unloaded condition, especially in order to come back from the second position, in which the stack of sheet-form print materials were released, to the first position in order to accept a new stack of sheet-form print materials. 
   The mass moments of inertia of the gripper are different from the mass moments of inertia of the combination of gripper and load, namely by the mass moment of inertia of the stack of sheet-form print materials. 
   An optimization may be provided in that the cam section is formed such that the rotation of the loaded gripper is executed at lower accelerations than the rotation of the unloaded gripper. If the movement of the loaded gripper is defined as movement in a first transport direction and in the opposite transport direction as a second transport direction, the optimization can advantageously be achieved in that the increase in slope of the cam in the first transport direction is lower at first than the increase in slope in the second transport direction. Because of this, there is an asymmetrical structure of the cam section that takes into account the mass ratios that are asymmetrical between the loaded and the unloaded gripper. Because of the slower acceleration of the stack of sheet-form print materials during rotation achieved by these measures, the required holding force of the gripper that is necessary to press the individual sheet-form print materials of the stack against each other during rotation can be decreased to avoid slipping of the individual pages of the sheet-form print material. 
   For example, this is important if, after transport and rotation from the gripper, the stack of sheet-form print materials will be subjected to a binding process, e.g. binding using a wire comb, plastic comb or spiral binding. In this process, an appropriate binding element will be threaded through a series of holes provided in the individual pages. The series of holes in the individual sheet-form print materials are caused to line up in the stack. If the individual series of holes are displaced during the rotation, this can lead to considerable complications during the following binding step. Therefore, secure clamping of the individual pages and thus the rotation of the stack of sheet-form print materials that is as gentle as possible is of great importance. 
   Advantageously, the guide may have a guide surface formed on just one side outside the intermediate section. Because of this, with a suitable design of the rotation unit, this can be taken upward out of the transport unit while the transport unit is still in connection with the carriage guide. In turn, this may make maintenance and/or installation easier. 
   In an advantageous embodiment according to an aspect of the invention, the rotation unit may have a spring unit that pre-stresses the lever along with the lever roller against the guide. This is especially advantageous with a one-sided design of the guide since because of this, continuous contact of the lever roller with the guide may be ensured. 
   In an advantageous manner, the rotation unit may have a spring unit that is dimensioned in such a way that the mass inertias of the loaded gripper are absorbed at the end of rotation. This is used in turn for a gentler braking of the rotation operation having the advantages described above. In this case, it is especially advantageous if this spring unit is the same spring unit that also pre-stresses the lever roller on the guide. 
   In an advantageous embodiment according to an aspect of the invention, the transmission is a timing belt drive with a timing belt and two timing belt pulleys. A timing belt is suitable, on the one hand, for damping the movements because of its elasticity, and, on the other hand, the teeth prevent the belt from slipping on the pulleys. 
   Although the invention was described in reference to preferred exemplary embodiments, the invention is not restricted to them, but can undergo changes and adaptations within its area of applicability.