Method of and apparatus for depalletizing commodities

Abstract

Successive palletized stacks of blanks in a layer of such stacks on a penetrable support of cardboard or the like are lifted off the support by a substantially horizontal plate- or blade-like implement which is caused to penetrate between the upper side of the support and the underside of a selected stack prior to lifting of the selected stack off the support for transfer onto a conveyor or into a blank converting machine, such as a cigarette packing machine. An optical or other suitable monitoring unit has one or more sensors which share the movements of the implement to detect, and to effect the generation of defect signals in response to the detection of, improper operation of the apparatus, such as the penetration of the implement through and subsequent lifting of a portion of the support with a selected stack.

What is claimed is:  
     
         1 . A method of removing a commodity from an upper side of a support by means of an apparatus which includes a substantially horizontal lifting implement movable in a plurality of directions including downwardly toward, upwardly away from and along the upper side of the support, comprising the steps of introducing the implement between the commodity and the upper side of the support; monitoring the position of at least one of the implement, the support and the commodity not later than upon completion of said introducing step and generating a signal at least when the monitored position departs from a predetermined position; and moving the implement and the commodity relative to and away from the support at least when the monitoring step does not result in the generation of a signal denoting that the monitored position departs from the predetermined position.  
     
     
         2 . The method of  claim 1 , wherein the commodity comprises at least one stack of superimposed substantially flat blanks.  
     
     
         3 . The method of  claim 1 , wherein said monitoring step is carried out at least in the course of said introducing step.  
     
     
         4 . The method of  claim 1 , wherein said monitoring step is carried out upon completion of said introducing step.  
     
     
         5 . The method of  claim 1 , wherein said signal is a defect signal, and further comprising the step of blocking said moving step in response to the generation of a defect signal.  
     
     
         6 . The method of  claim 5 , further comprising the step of correcting the monitored position in response to the generation of a defect signal.  
     
     
         7 . The method of  claim 1 , wherein said introducing step includes moving the implement dowardly at least close to the upper side of the support adjacent the commodity and thereupon advancing the implement along the upper side between the commodity and the upper side of the support.  
     
     
         8 . The method of  claim 1 , further comprising the step of lifting at least a portion of the implement and of the commodity above and normally away from the upper side of the support subsequent to said introducing step and prior to said monitoring step.  
     
     
         9 . The method of  claim 8 , wherein said monitoring step includes monitoring the position of the support.  
     
     
         10 . The method of  claim 9 , wherein said signal is generated when said monitoring step reveals a lifting of at least a portion of the support with said portions of the commodity and the implement.  
     
     
         11 . The method of  claim 9 , wherein said lifting step includes lifting portions of the commoditiy and of the implement through a distance in the range of approximately 10 mm.  
     
     
         12 . The method of  claim 9 , wherein said monitoring step includes optically scanning the position of the support.  
     
     
         13 . The method of  claim 9 , wherein said monitoring step includes mechanically scanning the position of the support.  
     
     
         14 . The method of  claim 9 , wherein said monitoring step includes the utilization of a fluid-operated monitoring device.  
     
     
         15 . Apparatus for removing commodities from an upper side of a support, comprising a displacing unit including a substantially horizontal lifting implement and means for moving said implement in a plurality of directions including downwardly toward, upwardly away from and along the upper side of the support so that the implement can be introduced between the upper side of the support and a selected commodity at the upper side; means for monitoring the position of at least one of said implement, the support and the selected commodity not later than upon completion of introduction of the implement between the upper side of the support and the selected commodity, including means for generating signals denoting the monitored position; and means for evaluating said signals.  
     
     
         16 . The apparatus of  claim 15 , wherein said generating means is arranged to generate defect signals when the monitored position departs from a predetermined position, said moving means being operative to move said implement and the selected commodity away from the upper side of the support at least in the absence of generation of a defect signal.  
     
     
         17 . The apparatus of  claim 15 , wherein said monitoring means includes means for monitoring the position of the support.  
     
     
         18 . The apparatus of  claim 17 , wherein said monitoring means comprises a position sensor carried by said moving means and extending toward the upper side of the support.  
     
     
         19 . The apparatus of  claim 18 , wherein said signals denote the position of the support beneath said implement.  
     
     
         20 . The apparatus of  claim 15 , wherein said monitoring means includes an optical sensor for the position of the support, said sensor being borne by said moving means.  
     
     
         21 . The apparatus of  claim 20 , wherein the upper side of the support reflects radiation and said sensor includes a source of radiation and means for directing radiation from said source against the upper side of the support, said signal generating means being operative to generate signals denoting the characteristics of radiation being reflected by the upper side of the support.  
     
     
         22 . The apparatus of  claim 15 , wherein said moving means includes means for moving at least a portion of said implement and at least a portion of the selected commodity upwardly to predetermined positions upon introduction of said implement between the upper side of the support and the selected commodity, said monitoring means including means for monitoring the position of the support in said predetermined positions of said portion of said implement and said portion of the selected commodity and said signal generating means being arranged to transmit to said evaluating means a signal denoting the monitored position of the support in said predetermined positions of said portions of said implement and the selected commmodity.  
     
     
         23 . The apparatus of  claim 15 , wherein said monitoring means is borne by said moving means and includes a mechanical sensor constituting said signal generating means.  
     
     
         24 . The apparatus of  claim 15 , wherein said monitoring means is borne by said moving means and includes a fluid operated sensor constituting said signal generating means.  
     
     
         25 . The apparatus of  claim 24 , wherein said sensor is a pneumatic sensor.  
     
     
         26 . The apparatus of  claim 24 , wherein said sensor includes a dynamic pressure transducer.