Abstract:
A delivery system ( 1 ) for flat material ( 2 ), in particular sheet paper, with a guideway ( 3 ) and at least two glide elements ( 4 ) extending in the direction of conveyance ( 10 ), whose surface ( 5 ) opposite the guideway ( 3 ) is elevated in construction and the guideway exhibits substantially reduced friction vis-a-vis the flat material.

Description:
FIELD OF THE INVENTION 
     BACKGROUND OF THE INVENTION 
     The invention relates to a delivery system for flat material, in particular sheet paper, with a guideway and at least two glide elements extending in the direction of conveyance, whose surface opposite the guideway is elevated. 
     A delivery system is disclosed in DE-90 02 392.7 U1. According to the subject matter of this DE disclosure, ribbed projections are provided on a guideway, as a result of which sheets to be delivered slide on these projections until they reach their defined final position. The danger exists in this connection that the first sheet to be delivered will not reach its final position if it misslides. A slanting position may arise if the sheet to be delivered misslides to one side. 
     SUMMARY OF THE INVENTION 
     The object of the invention is to make available a delivery system with which a flat material can be conveyed safely into a defined delivery position. 
     The object is solved in accordance with the invention in that the surfaces of the glide elements opposite the surface of the guideway exhibit substantially reduced friction vis-à-vis the flat material. 
     The advantage of the invention lies in the fact that easy sliding on the surface of the glide elements up to the defined delivery position is assured. Further advantages are obtained through expedient refinements. 
     One particularly expedient refinement provides that the guideway is a delivery table and that an increased friction of the guideway surface and the height differential of this surface to the surface of the glide elements are dimensioned in such a way that a flat material, upon completion of its conveyance, deposits itself non-slippably on the surface of the guideway. By virtue of this refinement, the flat material slides on the surface of the glide elements until it comes to rest and then, overcoming the height differential, deposits itself on the surface of the guideway whose increased friction ensures that slippage of the delivered flat material and, accordingly, other flat materials being stacked into a pile on the first material delivered, is no longer possible. The higher the stack, the greater the resulting bearing pressure, and secure stack position is thereby assured. 
     One expedient refinement provides that the glide elements are constructed as strips glued to the surface of the guideway. As a result thereof, the glide elements are substantially easier and more economical to produce than is the case with the state of the art cited at the outset because there they are incorporated into the delivery table. The construction as glued-on strips also offers the advantage that the glide elements can be made from a material other than that of the guideway, for example, from plastic which, vis-à-vis the flat material to be delivered, exhibits lower friction than that, for example, of the metal of the delivery table. It has been shown that the glide elements are expediently made of polytetrafluoroethylene, commonly referred to as Teflon®. 
     Conveyance of the material to be delivered can occur in different ways. Conveyance is possible by the upstream machine or a conveyance and positioning device can be provided. Good interaction with the glide elements in accordance with the invention is given if conveyor rollers with high friction surfaces and a control mechanism are provided which convey the flat material in a predetermined manner. The flat material is expediently delivered by conveyor rollers in a defined manner by conveying it to its delivery position. The above-described effect can be achieved if, during conveyance, the flat material slides on the glide elements and after conveyance has come to a stop, delivery occurs on the surface of the glide elements with increased friction. 
     The final position of the flat material and, accordingly, the defined delivery position can be achieved either by the above-mentioned conveyor rollers or it is possible for defined delivery to occur by a stop at the end of the guideway. Of course, both steps can also be combined together. A further measure to achieve defined delivery in combination with the steps already proposed or acting by itself can include providing a surface with increased friction in the back area of the delivery table. This surface is preferably provided at least at the height of the gliding element surface. As a result thereof, the flat material deposits itself with its back area on this surface with increased friction, whereby first its movement is absorbed and thereafter protection against shifting is achieved. The surface with increased friction also is expediently formed by a glued-on strip. Rubber has shown itself to be an advantageous material in this connection. 
     In order to ensure that the flat material is conveyed over the surface with increased friction, tongues can be provided by which the flat material slides over the surface with increased friction and which after delivery of the material can be withdrawn from the delivery area. It is also possible in this connection for the tongues to completely or partially cover the surface with increased friction. At the same time, this surface with increased friction and the tongues can act together with the conveyor rollers and, if necessary, even with a hold-down clamp to ensure positioning of the material so that the flat material first reaches the defined delivery position and then is securely positioned. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention is elucidated in the following on the basis of the drawing, with references to further refinements. Shown are, in 
     FIG. 1 an exemplified embodiment in perspective view, 
     FIG. 2 a further exemplified embodiment in a side view. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 shows an exemplified embodiment of a delivery system  1  in perspective view. By way of example, the delivery system  1  is provided at the delivery of a printing press  8  and is constructed as a delivery table  20 . The purpose of the delivery table  1  is in conveying flat material  2  (see FIG. 2) up to a defined delivery position  9  and to position the front edges of the flat material  2  in this defined delivery position  9  such that a stack is formed. 
     In this connection, the positioning of the first flat material  2  is the most critical as too heavy friction on the delivery table  20  can have the result that the defined delivery position  9  is not achieved or not achieved in the exact alignment. In order to effect his, the invention provides that glide elements  4  extending on a guideway  3  in the direction of conveyance  10  are disposed with surfaces  5  which exhibit vis-à-vis the flat material  2  the lowest possible friction. In this manner it is achieved that the flat material  2  is conveyed in the direction of the arrow  10  and at the same time only slides on the surfaces  5  of the glide elements  4 . When thereafter the flat materal  2  comes to a stop with its front edge in the defined delivery position  9 , then the flat material  2  deposits itself in such a way that it comes into contact with the surface  6  of the guideway  3  and is securely held because this surface  6  exhibits high friction vis-à-vis the flat material  2 . 
     In order to safely assure this function, provision is made for a height differential between the surfaces  5  of the glide elements  4  and the surface  6  of the guideway  3 , which is dimensioned such that the flat material, during conveyance, does not yet come into contact with the surface  6  but which, however, when at a standstill, does deflect and, at the same time, touches the surface  6  of the guideway  3 . In addition to the corresponding dimensioning of the height differential of the surfaces  5  and  6 , further provision can be made that distancing of the glide elements  4  is dimensioned in such a way that this deflection is achieved. It can also be provided for this reason that not only two glide elements  4  extend along the guideway  3  but, rather, that a larger number is provided, as a result of which narrower surface strips  6  of the guideway  3  arise and heavier deflection of the flat material  2  is required, which takes place slower and, as a result thereof, contact of the surface  6  only occurs when the material  2  is at a standstill. 
     To achieve the defined delivery position  9  by the flat material  2 , a surface  12  with increased friction can be provided in the back area  11  of the delivery table  20 . This increased friction brakes the flat material  2  and ensures secure positioning during delivery. Conveyor rollers  7  can also be used for secure positioning. 
     FIG.  1  and FIG. 2 show a conveyor roller  7  construction with additional elements  13  and  16  to achieve a defined delivery position  9 . The conveyor rollers  7  are expediently combined with tongues  16 , in which case the conveyor rollers  7  with their high friction surface vis-à-vis the flat material  2 , convey the flat material  2  through rotation until the defined delivery position  9  is attained and then brake at the correct moment. The conveyor rollers  7  expediently act together with the tongues  16  which exhibit low friction and are disposed such that the flat material  2  slides on the tongues  16  and is conveyed by the conveyor rollers  7 . 
     When a flat material  2  reaches the defined delivery position  9 , a hold-down clamp  13  is actuated with a vertical movement in such manner that it holds the flat material  2  in the defined delivery position  9 . The conveyor rollers  7  subsequently lift through a vertical movement  19  and the tongues  16  are retracted in the direction of the double arrow  17  counter to the direction of conveyance  10 , whereby the back end of the flat material  2  deposits itself. 
     This process takes place during the delivery of all sheets of the flat material  2 ; it is, however, above all advantageous for the first sheet of flat material  2  because this ensures that the flat material  2  slides safely over the surface  12  with increased friction and then reaches, by the surfaces  5  with low friction, the defined delivery position  9  and is securely positioned by the surfaces  6  and  12  with increased friction. For delivery of the next flat material  2 , the tongues  16  are repositioned through a horizontal movement  4  and a vertical movement  5  into the position shown and the conveyor rollers  7  drop in such a way that a flat material  2  can again be conveyed between the tongues  16  and the conveyor rollers  7  up to the defined delivery position  9 . The horizontal movement  14  of the holding-down clamp  13  functions as retraction means so that a new sheet can be delivered. In the exemplified embodiment of FIG. 2, a stop  21  is provided in order to attain the defined delivery position  9 . 
     The description is only exemplary in nature; it is, of course, possible to combine the glide elements  4  in accordance with the invention also with a different kind of conveyance and positioning device  22 , exclusively with the conveyor rollers  7 , or in any combination of conveyor rollers  7 , surface  12  with increased friction and/or stop  21 . The disposition of the delivery system  1  as a delivery table  20  or at a printing press  8  is also merely illustrative. The delivery system  1  can have any refinements which ultimately accomplish the purpose that a flat material can be conveyed into a defined delivery position  9 . 
     LIST OF REFERENCE SYMBOLS 
       1  delivery system 
       2  flat material 
       3  guideway 
       4  glide elements 
       5  gliding element surface 
       6  guideway surface 
       7  conveyor rollers 
       8  printing press 
       9  defined delivery position 
       10  arrow: direction of conveyance 
       11  back area 
       12  surface with increased friction 
       13  holding-down clamp 
       14  double arrow: horizontal movement of holding-down clamp 
       15  double arrow: vertical movement of holding-down clamp 
       16  tongues 
       17  double arrow: horizontal movement of tongues 
       18  double arrow: vertical movement of tongues 
       19  double arrow: vertical movement of rollers 
       20  delivery table 
       21  stop 
       22  conveyance and positioning device