Patent Publication Number: US-6338484-B1

Title: Sorting apparatus

Description:
The present invention relates to an apparatus for controlled sorting by way of deflection of sheet-like objects such as veneer sheets in a desired manner in a continuous train of sheets from one transport conveyor of said sheets to another conveyor. The need for this kind of apparatus occurs, e.g., in the manufacture of plywood when veneer of different grade must be sorted into respective stacks or to a separate post-processing step. 
     Deflection of a veneer sheet is conventionally based on information obtained from the sheet by means of a suitable monitoring system located on the travel path of the sheets. Next on the sheet travel path, there are located apparatuses that on the basis of this information can deflect the sheet from one path to another. The deflecting apparatuses are adapted to cooperate with the conveyor types used and are based on different kinds of picking, lifting and pressing means that momentarily can be actuated into their working positions. These deflecting means have in common that they are, when actuated, stationary in respect of the travel of the moving sheets. Obviously, this causes a stop in the travel of the sheet to be deflected. As known in the art, attempts have been made to minimize the disadvantages of the stopping deflection step by virtue of arranging the deflection step to occur at a maximized speed. 
     In the apparatus according to the invention, the stopping effect imposed on the sheet to be deflected by the deflecting means or apparatus is entirely eliminated during the sorting of veneer sheets in a desired manner onto different travel paths. The apparatus includes a sheet-moving transport conveyor comprising parallel-travelling, spaced-apart moving transport conveyor elements such as belts, and a deflecting conveyor travelling locally at least over a certain distance substantially in the same direction with the first conveyor. The transport conveyor has thereto adapted lifting means that in a controlled manner can reach above the transport level of the transport conveyor via the gaps arranged between said conveyor elements, said lifting means being arranged to be elevated into an abutting position against the deflecting conveyor and simultaneously coinciding with the movement of the latter conveyor. 
    
    
     In the following, the invention will be examined in greater detail by making reference to the attached drawing illustrating an exemplifying embodiment, wherein 
     FIG. 1 shows the principal parts of the apparatus in the home position of the apparatus function; 
     FIG. 2 shows the apparatus in a working position; and 
     FIG. 3 shows the apparatus in a position where the working function is completed. 
    
    
     The apparatus illustrated in the diagrams comprises a conveyor  4  serving as a transport conveyor for fetching veneer sheets, e.g., from a clipper following a veneer lathe. This conveyor may consist of a plurality of parallel-operating belts or the like transport conveyor elements on which the veneer sheets being transported can travel. In a prior stage of the transport operation, the veneer sheets have been graded, e.g., by their size and/or quality properties on the basis of which selected sheets from a lot are desired to be deflected onto different travel paths. 
     For this purpose, the apparatus includes a second conveyor  3  serving as a deflecting conveyor. In the illustrated embodiment, the deflecting conveyor is adapted to travel above the transport conveyor  4 , parallel thereto. The type of the deflecting conveyor in the exemplifying embodiment may be, e.g., a stick-and-carry conveyor or a vacuum conveyor that with its downward oriented transport means can support and convey forward a veneer sheet lifted in a close proximity to the conveyor surface. Advantageously, the deflecting conveyor is adapted to travel at the same speed with the transport conveyor  4 . 
     According to the invention, there are adapted lifting means  5 ,  6 ,  7  to cooperate with the transport conveyor  4 , said lifting means being capable of reaching in a controlled manner above the transport level of the transport conveyor  4  so as to meet the underside of the deflecting conveyor  3 . The lifting means are implemented as rotary elements having the direction and speed of their motion arranged to cooperate in synchronism with the transport movement of the deflecting conveyor  3 . By virtue of this arrangement, a veneer sheet  1  travelling on the transport conveyor  4  can be elevated with the help of the lifting means  5  or  7  off from the first conveyor by controlling said lifting means to rotate about its shaft  6 , whereby said means elevates the sheet into a contact with the surface of the deflecting conveyor  3 . As the movement of the lifting means is adapted to occur synchronized with the movement of the deflecting conveyor  3 , the veneer sheet will smoothly bend upward for being conveyed by this conveyor. To adhere the sheet  1  to the deflecting conveyor, it may be pressed against the nails projecting downward from the underside of the deflecting conveyor  3  or, alternatively, the sheet may be elevated into the effective region of suction when the conveyor  3  is implemented as a vacuum conveyor. Advantageously, the speed of the transport conveyor  4  is also synchronized to the speed of the deflecting conveyor  3  and the tangential speed of the rotary movement of the sheet-lifting means, thus eliminating all possible causes related to the sheet deflection actions that could disturb the continuous travel of the veneer sheets.