Method and Device for Separating Flat Consignments

Abstract

In successive acceleration stages, the nominal take-off speed of the take-off elements in each acceleration stage is higher than the nominal take-off speed of the take-off elements of the respective preceding acceleration stage in the direction of transport. In the respective acceleration stage, the speed of the consignment lying on the take-off element(s) is measured by a sensor T 1 positioned on the side of the take-off element. As soon as the speed of the consignment lying on the take-off element, which is measured in the feed region of each acceleration stage by the sensor positioned on the side of the take-off element, deviates by a defined value from the nominal speed of the take-off element in the acceleration stage, i.e., as soon as the consignment is received in the acceleration stage practically without slippage, the speed of the take-off element of the preceding acceleration stage is reduced.

1 . A method for separating flat consignments by means of a plurality of successive take-off elements having acceleration stages, whereby the take-off elements act on one side on sides of the consignment in a take-off plane, whereby 
 a nominal take-off speed of the take-off elements in each acceleration stage is higher than a nominal take-off speed of the take-off elements of the acceleration stage upstream in a direction of transport at any one time,    a speed of the consignment lying on the take-off elements is measured in a feed region of the respective acceleration stage by means of a sensor T 1  located on a side of the take-off element,    as soon as the speed of the consignment lying on the take-off elements, which is measured in the feed region of each acceleration stage by means of the sensor T 1  located on the side of the take-off elements, deviates by only a defined low value from the nominal speed of the take-off elements in said acceleration stage, the speed of the take-off elements of the upstream acceleration stage in the direction of transport is reduced.    
   
   
       2 . The method according to  claim 1 , whereby the sensors T 1  are located between the acceleration stages.  
   
   
       3 . The method according to  claim 1 , whereby the speed of the consignments which can be sensed from the side facing away from the take-off elements in the region of the acceleration stages downstream in the direction of transport is additionally measured by means of sensors T 2  located on the side facing away from the take-off elements.  
   
   
       4 . The method according to  claim 1 , whereby the speeds of the take-off elements and of the consignments driven by them are compared with one another in order to determine slippage and, when deviations lying above a defined limit value are exceeded, a service signal is generated.  
   
   
       5 . The method according to  claim 3 , whereby 
 as soon as the speed of the consignments lying on the take-off elements, which is measured between the acceleration stages by means of the sensor T 1  located on the side of the take-off elements, deviates by only a defined low value from the nominal speed of the take-off elements of the acceleration stage downstream in the direction of transport at any one time, the speed of the take-off elements of the upstream acceleration stage in the direction of transport is reduced,    the speed of the consignments is measured in the region of each acceleration stage downstream in the direction of transport by means of a sensor T 2 , which is located on the side facing away from the take-off elements, and as soon as the thus measured speed of the consignments deviates by only a defined low value from the nominal speed of this downstream acceleration stage after the reduction of the speed of the take-off elements in the respective upstream acceleration stage acceleration stage, the speed of the take-off elements of the respective upstream acceleration stage is again increased to its nominal speed, and as soon as the leading edge of a consignment detected by means of the sensor T 2  from the downstream acceleration stage is registered as a measured jump in speed to vA 1 , the speed of the take-off elements for the respective upstream acceleration stage is changed to the value 0,    as soon as the consignment speed measured by the sensor T 1  between the two adjacent acceleration stages has dropped from the speed of approximately vA 2  to the value 0, the take-off elements for the respective upstream acceleration stage are accelerated to the nominal take-off speed and    the distance between the beginning of the respective acceleration stage and the associated sensor T 2  and thus the holding point for the leading edge of the following consignment is chosen depending on the difference between the nominal speeds of the respective acceleration stage and the upstream acceleration stage such that the two adjacent consignments exhibit a defined distance from one another at the end of the respective acceleration stage.    
   
   
       6 . The method according to  claim 5 , whereby as soon as the speed of the consignments lying on the take-off elements, which is measured between the acceleration stages by means of the sensor T 1  located on the side of the take-off elements, deviates by only a defined low value from the nominal speed of the take-off elements of the acceleration stage downstream in the direction of transport at any one time, the speed of the take-off elements of the upstream acceleration stage in the direction of transport is reduced to the value 0.  
   
   
       7 . A device for separating flat consignments by means of a plurality of successive take-off elements having acceleration stages, whereby the take-off elements act on one side on sides of the consignment in a take-off plane, whereby 
 a nominal take-off speed of the take-off elements in each acceleration stage is higher than a nominal take-off speed of the take-off elements of the acceleration stage upstream in a direction of transport at any one time,    a sensor T 1  for measuring a speed of the consignment lying on the take-off elements is located on the side of the take-off element in the feed region of the respective acceleration stage, and    a control unit is provided which is implemented such that as soon as the speed of the consignment lying on the take-off elements, which is measured in a feed region of each acceleration stage by means of the sensor T 1  located on the side of the take-off elements, deviates by only a defined low value from the nominal speed of the take-off elements in said acceleration stage, the speed of the take-off elements of the upstream acceleration stage in the direction of transport is reduced.    
   
   
       8 . The device according to  claim 7 , whereby the sensors T 1  are located between the acceleration stages.  
   
   
       9 . The device according to  claim 7 , whereby sensors T 2  are additionally located in the region of the acceleration stages downstream in the direction of transport on the side facing away from the take-off elements which measure the speed of the consignments that can be sensed from the side facing away from the take-off elements.  
   
   
       10 . The device according to  claim 7 , whereby the sensors T 1 , 2  for measuring the consignment speed are implemented as one of rollers and bands, running on consignment surfaces, in fixed locations and driving tachogenerators, whereby rotational speeds or a voltage generated by the tachogenerators serves as a measure of the consignment speed.  
   
   
       11 . The device according to  claim 7 , whereby controlled powered take-off belts with defined coefficients of friction are provided as take-off elements.  
   
   
       12 . The device according to  claim 11 , whereby the take-off elements have controllable vacuum chambers in order to draw the consignments onto the take-off belts.