DESTACKING DEVICE WITH THICKNESS BASED FEEDBACK CONTROL

Abstract: The device for removing flat objects from a stack comprises a magazine (2) in which are stacked on edge flat objects to be serialized and a vertical destacking plate (6) disposed directly in front of the magazine and against which the first object (O1) of the stack will be pressed, said first object of the stack being ejected in a direction (E) perpendicular to the direction of advance (D) of the stack of flat objects in the magazine. It furthermore comprises a means (14, 15) for measuring the thickness of each flat object pressed against the destacking plate, this thickness measurement serving for the feedback control of the movement of the stack of flat objects in the magazine. Application to a postal sorting machine.

Description: DESTACKING DEVICE WITH THICKNESS BASED FEEDBACK CONTROL flat objects The invention relates to a device for removing fiat objects from a stack compπsing a magazine in which are stacked on edge flat objects to be seπa zed and a vertical destacking plate disposed directly in front of the magazine and against which the first object of the stack will be pressed, said first object of the stack being ejected in a direction perpendicular to the direction of advance of the stack of fiat objects in the magazine The invention applies most particularly to a device for removing flat objects from a stack for a postal sorting machine operating in synchronous mode in contemporary destackers for postal sorting machines operating in synchronous mode, the stack of flat objects is pushed step by step toward the destacking plate only after the first object of the stack pressed against this destacking plate has been completely ejected from the destacker The users of this type of sorting machine are seeking to be able to process an ever broader spectrum of fiat objects, that is to say fiat objects whose height, width and thickness dimensions vary greatly When a very thick object is ejected from the destacker, an empty space is created between the destacking plate and the new first object of the stack to be seπalized and the idea on which the invention is based is to fill this empty space as rapidly as possible so as to increase the destacking throughput For this purpose the subject of the invention is a device for removing flat objects from a stack compπsing a magazine in which are stacked on edge fiat objects to be seπalized and a vertical destacking plate disposed directly in front of the magazine and against which the first object of the stack will be pressed in order to be ejected in a direction perpendicular to the direction of advance of the stack of flat objects in the magazine, which furthermore compπses a means for measuππg the thickness of said first object of the stack of objects pressed against the destacking plate, this thickness measurement serving for the feedback control of the movement of the stack of fiat objects in the magazine This thickness measurement is earned out in particular by means of at least one pair of elastically deformabie wheels made of an elastomer and between which is pinched each flat object ejected from the destacker and two laser telemeters mounted between said destacking plate and the elastically defonπable wheels, each telemeter measunng the posrtion of a face of the flat ob j ect with respect to a central reference axis More particularly the signals delivered by the laser telemeters are processed so as to determine the thickness of each flat object just before it is completely ejected from the destacker and just 5 after it is pinched between the two elastomer wheels thereby making rt possible meanwhile to advance the stack of flat objects toward the destacking plate that is to say to bnng forward the nsing of this stack of flat objects toward the destacking plate These elastomer wheels help by pinching each flat object on edge to improve the accuracy of the thickness measurement and hence to make the _ Z operation of the destacker more reliable According to a particular embodiment of the destacker according to the invention each wheel compnses a hub joined to an annular tread stnp by elastically deformable circular arcuate veins each vein having its two ends for joining to the hub and to the annular tread stnp of the wheel which are situated on ^ 5 a spoke of the wheel The particular circular arcuate profile of the veins with points of attachment situated on the spoke of the wheel makes it possible upon the squeezing of the wheel to make the elastomer work over the entire length of the veins without creating a stress concentration zone, thereby helping to prolong the lifetime of the wheels and hence to increase the availability of the system for 20 measunng the thickness of flat objects The destacking device according to the invention is descnbed hereinafter in detail hereinbelow in conjunction with the single figure which shows same very diagrammatically The device 1 for destacking flat objects shown in the figure is 25 intended to be mounted in a synchronous postal sorting machine It compnses a magazine 2 in which are stacked, on edge flat objects to be senalized and a palette 3 intended to push the stack of flat objects on edge in a longitudinal direction D The palette 3 is mounted movably along a rail 4 which extends in the direction D and the palette is moved in this direction by a stepper 30 type motonzation 5 The destacking device 1 further compnses a vertical fixed destacking plate which extends in the direction E perpendicular to the direction D and along which is ejected each first object of the stack at the exit of the destacker As is visible in the figure, the destacking plate 6 exhibits an opening 7 35 in the plane of which is moved, in the hoπzontal direction E a perforated stnp 8 which cooperates with a suction nozzle (not represented) mounted behind the perforated stnp When the stack of flat objects is pushed by the palette 3 toward the destacking plate 6 the first object such as 01 of the stack is applied hard against the destacking plate 6 and, under the combined effect of the suction force of the nozzle and of the motion of the perforated stnp, it is ejected in the direction E at the exit of the destacker as illustrated by the arrow E In front of this destacking plate 6 on the exit side of the destacker there is provided at least one pair of elastically deformable motoπzed elastomer wheels 9 and 10 between which the flat object ejected from the destacker 6 is pinched These two motoπzed wheels 9 and 10 each have a fixed-position vertical rotation axle Each wheel compnses a hub 11 joined to an annular tread stnp 12 by elastically deformable circular arcuate veins 13, each vein having its two ends for joining to the hub and to the annular tread stnp of the wheel which are situated on a spoke of the wheel These two wheels are mounted so as to take responsibility for the movement of the object 01 at the exit of the destacker also to press on these two faces so as to allow accurate measurement of the thickness of the flat object This thickness measurement is ensured by two laser telemeters 14 and 15 mounted between the wheels 9 and 10 and the destacking plate 6 on either side of the plane in which the first object of the stack is ejected at the exit of the destacker so that each laser telemeter measures the distance between a face of the flat object and a reference axis, for example the mid-axis parallel to the direction E and passing between the two wheels 10 and 11 , as illustrated by the double arrow The measurement signals delivered by the laser telemeters 14 and 15 are processed by an electronic computation unit (not represented) which feedback controls the motoπzatioπ 5 of the palette 3 in such a way as to bπng forward the movement of the stack of flat objects to be seπalized toward the reference plate by a distance corresponding to the measured thickness of the first object of the stack and to do so even before this first object of the stack has been ejected from the destacker Furthermore, a system 16 for measunng the load applied by the stack of flat objects against the destacking plate 6 is provided so as to regulate the advance of the stack of flat objects in the magazine 2 This system 16 can be designed according to two different pπnαples It may firstly entail a system for detecting a force threshold compπsing a pad illustrated in the figure, which is disposed in an aperture of the plate 6 so as to be in contact with the stack of flat objects and which is mounted on an oscillating lever (not represented) disposed behind the plate 6 The flat objects advancing on the magazine wiil be pressed against this pad The lever carrying the pad, returned into posrtion by a calibrated spπng, is equipped with a flag making it possible to blank off an optoelectronic cell if the flag passes through a predetermined posrtion corresponding to a certain load applied to the pad The blanking off of the cell is used to halt the movement of the stack of flat objects in the magazine It is therefore understood that in this case the thickness measurement tnggers the movement of the stack of flat objects in the magazine whilst the load measurement controls the stoppage of the movement of the stack of flat objects in the magazine According to a vaπaπt the load measurement can be earned out with a strain gauge and in this case the pad is mounted on a strain gauge bar which delivers a continuous signal making it possible, in combination with the thickness ) measurement, to regulate the speed of movement of the stack of flat objects in the magazine, that is to say to slow down the movement of the stack of fiat objects in tandem with an increase in the load measured by the system 16 The arrangement of the destacker according to the invention thus helps to increase the rate of destacking of flat objects

Claims: CLAIMS 1 A device for removing flat objects from a stack compπsing a magazine (2) in which are stacked on edge flat objects to be seπalized and a vertical destacking plate (6) disposed directly in front of the magazine and against which the first object (01) of the stack will be pressed, said first object of the stack being ejected in a direction (E) perpendicular to the direction of advance (D) of the stack of flat objects in the magazine, which furthermore compnses a means (14, 15) for measunng the thickness of each flat object pressed against the destacking plate, this thickness measurement serving for the feedback control of the movement of the stack of flat objects in the magazine 2 The device as claimed in claim 1 , compπsing at least one pair of elastically deformable wheels (9, 10) made of an elastomer and between which is pinched each flat object ejected from the destacking plate and two laser telemeters (14, 15) mounted between said destacking plate and the elastically deformable wheels. 3. The device as claimed in claim 2, wherein each wheel compnses a hub (11) joined to an annular tread stnp (12) by elastically deformable circular arcuate veins (13), each vein having its two ends for joining to the hub and to the annular tread stnp of the wheel which are situated on a spoke of the wheel 4 The device as claimed in one of the preceding claims, furthermore compπsing a system (16) for measunng the load applied by the stack of flat objects against the destacking plate, this load measurement serving to regulate the movement of the stack of flat objects in the magazine

Inventors: CHAUME FRANCOIS, DARROU FABRICE, TELUOB JEAN-MARC, CHAUME, FRANCOIS, DARROU, FABRICE, TELUOB, JEAN-MARC
Applicants: ATECS MANNESMANN AG, CHAUME FRANCOIS, DARROU FABRICE, TELUOB JEAN MARC, CHAUME, FRANCOIS, DARROU, FABRICE, TELUOB, JEAN-MARC
Application year: 2000
Main classification: B65H1
IPC codes: B65H1