CA1214187A - Device for dynamic storage of flat objects - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

Flat objects such as envelopes and the like which are stored on edge against each other by a stationary stacker are grouped together in packets of variable thickness within movable compartments of a storage magazine. The front and rear ends of the compartments are closed by intercalary members which are displaced independently towards a stationary unstacker by means of separate conveying chains. The intercalary members are caused by retractable catch-strips to cooperate in pairs with the conveying chains in order to form each time the front and rear ends of one compartment and to transport a corresponding packet of objects along the magazine towards the stacker.

Description

A DEVICE FOR DYNAL~IIC STORAGE OF FLAT OBJECTS

BACKGROUND OF THE INVENTION
This invention relates to a device for dynamic storage of flat objects and more particularly of thin objects such as, for example, letters (mail envelopes or the like) or else checks, invoices, dispatch notes or similar documents~
French patent No 77 05935 granted to the present Applicant has already disclosed an installation for the arrangement of sets of objects in stacks or in rows. In this installation, a magazine equipped with a jog~ing bench is associated with a plurality of intercalary members. These members define a set of compartments with the ~loor of the magazine and the skirtboards of the jogging bench. The volume of these compartments is determined by design. Conveying means comprising a chain attached to the intercalary members permits forward dis~
placement of these compartments up to an unstacking head.
The comparbments of this installation are intended to receive flat objects placed on edge such as mail envelopes, for example, and the mechanism has the aesign ~unction of bringing the objects towards an unstacking head during its movement of forward travel.
In the ex~nple described r the above-mentioned unstacking head is of the pnewnatlc type and comprises a rotary extracting drum having an axis parallel to the surface of the objects. A partial vacuum is applied to the perforated wall of the extracting drum from a stationary chamber connected to a source of fluid at negative pressure. In consequence, the first flat obj~ct to be brought into contact with this drum will be applied against this latter by suction. The drum is driven in rotation about its axis and causes extraction of the aspirated object as a result of its movement of rotation.
Ancillary means are provided for retaining the object which ~ollows the one being extracted. On the downstream side of the drum, the belt conveyor collects the extracted objects ~or subsequent processing. The operation is repetitive in order to ensure withdrawal of all the objects from a compartment, the compartments being unstacked in succession.
In this installation, loading of the compart-ments is carried o~lt by hand. In this case in particular, the operator takes care to place the flat objects within the compartments located nearest the unstacker as a function of the stock which is present in the magazine.
One attempt o replace the operator has consisted in placing a stacking head opposite to the first empty compartment of the stock. Since the state of the stock is variable, it proved necessary to design a movable stacking head. The mobility of this stacking head, however, is the , .

cause of many disadvantages. Bo-th a stacker and an un stacker can in fact be equipped with a rotary drum, a controlled-vacuum system and a set of actuators and detectors. This configuration results in a high degree of mechanical complexity in relation to the number o components which have to undergo displacements. Diffi-culties are also involved in the positioning or transfer of intercalary members with a variable abscissa. A final point is that, especially by reason of its inertia, the step-by-step displacement o~ this assembly as a function of repetitive stacking of objects results in unacceptable deficiencies from the point of view o~ operational reliability.

SUl~MARY OF THE INVENTION
The object oE the invention is to overcome the disadvantages mentioned in the foregoing and in particular to propose a device for large-capacity dynamic storage by making use of a set of stationary stackers and unstackers associated with a storage magazine for transporting objects in an original manner.
The invention proposes a device for dynamic storage of flat objects comprising a stacker for placing all the objects to be stored on edge against each other and within a storage magazine provided with successive compartments delimited by intercalary means, said inter-calary means being displaced by conveying means, and an ~2~ 7 unstacker for withdrawing the objects stored in the com-partments. The distinctive feature of the invention l~es in the fact that the stacker and unstacker are stationary and that the intercalary means are independent of the conveying means and are caused to cooperate in pairs with said conveying means by retractable locking means in order to form each time the front and the rear ends of one com-partment aforesaid and in o~der to transport a correspond-ing packet of objects along the magazine towards the unstacker BRIEF DESCRIPTION OF THE DRAWINGS
Fig. lA is a schematic diagram of the device according to the invention.
Fig 5 . lB and lC show a mode of operation of the conveying means of the device according to the invention.
Fig. 2 shows the arrangement of the control means for the aforesaid mode of operation.
Figs. 3A, 3B, 3C, 4A, 4B, 5 and 6 show examples of construction of the intercalary means according to the invention.
Figs. 7A and 7B are flow diagrams defining the operation of the conveying means.
In these different figures, the same reerences designate the same eIements.

DESCRIPTION OF THE PREFERRED EMBODIMæNTS
There is shown in Fig. lA the general arrangement of the storage device according to the invention. A
stationarily fixed stacking head or stacker 1 has the function of stacking flat objects 3 on edge within a magazine 2. The flat objects 3 are grouped together in packets 4 by a set of intercalary means 5 and 6 and are supported by the floor 7 of the magazine. One or two jogging skirtboards located in planes parallel to the plane of the figure on each side of the packets 4 complete the construction o the moving compartments 8. The com-partments thus formed are brought by a conveying means 9into contact with an unstacking head 10 or unstacker.
The operation of the dynamic storage device according to the invention is as follows : at the time of arrival of the flat objects which may take place in a random order, the stackæ 1 stacks these objects within a stacking compartment provided solely with a front inter-calar~ means 6, so designated because it is located at the front end of the packet as this latter passes through the storage magazine. When stacking of the packet is completed, which can be determined on the basis of either a yiven number of objects to be stacked or a~"g~ven thick-ness of the packet to be formed or a given waiting period after stacking of the last object, a pair of rear inter-calary means 5 and front intercalary means 6 is brought ~5 up to the rear of the packet which is being stacked. This pair is then separated, with the result that the rear 87~

intercalary means 5 leaves with the formed packet whilst the new front intercalary means 6 remains in a waitin~ or standby position downstream of the stacker in order to receive the fresh supply of objects to be stacked. The compartment 8, the thickness of which is variable for the reasons mentioned above, therefore travels through the magazine and comes into abutting contact with the packets which await unstacking and are contained in the storage zone of the magazine. The storage zone of the magazine designates a zone in which the packets can be stored while awaiting unstac~ing.
As the unstacking operation takes place, an unstacker 10 which is similar to the one described in the foregoing withdraws the objects from the packets. During this operation, all the stored compartments advance towards the unstacker 10 at the same time and at the un-stacking rate. Since the compartments are stored one behind the other, pairs of front intercalary means 6 and rear intercalary means 5 are re-formed. Durin~ forward travel, when these pairs of intercalary means reach the vicinity of the unstacking head 10, they are retracted in order to permit withdrawal of the objects from the f ollowing packet.
It is therefore apparent from the effects herein-above described that the device accordin~ to the in~entionpermits dynamic storage of objects and also that the . . .

stackers and unstackers are stationary. Finally, since the rate of travel of the formed packets up to the poin~
of abutting contact with the last packets of the stock is higher than the rate of stacking or unstacking, the dev.ice according to the invention does not produce any delay in processing by the unstacker 10 in the case of flat ob]ects stacked by the stacker 1. This is the situation which would prevail in particular if a station-ary stacking head had been placed at the end of the installation of the prior art cited earlier In a very simplified embodiment of the invention, the storage magazine is provided with only two front intercalary means and two rear inte~calary means which are arranged in alternate sequence and travel in a loop or closed circuit 11. Moreover, the conveying means comprise a single chain 17 which extends over the entire length of the system and travels on a closed path. The chain comprises a lug 18 applied against a yieldable catch-strip 12 located beneath the lower end of the rear inter-calary means 5. The rear intercalary means 5 thus com-prise the yieldable catch-strip 12 attached to a carriage 15 which supports a set of thrust-fingers 13. In this embodiment, the front intercalary means 6 comp~ise a carriage 16 which supports a set of retaining-fingers 14.
The yieldable catch-strip 12 can consist of a steel blade which has a predetermined degree of flexi~ility and is .

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applied against the lu~ 18 of the chain. When the packe-t thus pushed forwards is abuttingly applied against the stock which awaits unstacking~ the flexible catch-s-trip is subjected to hiyh stress, bends back momentarily and the chain lug escapes. The chain lug again escapes beneath the catch-strip of the other rear carriage 15 which is waiting in the stock. The chain thus continues to rotate, the packets being propelled towards the unstacker in jerks each time the lug passes. By virtue of the compression exerted on the objects contained in the packets at the time of each forward displacement, the reaction of these làtter is such as to exert a forward thrust on the objects to be unstacked before a new com-pression cycle is restored by the next passage of the chain lug.
When the last object of a packet approaches the unstacker, the pair of front and rear intercalary means withdraws. This situation is made possible by a distinctive feature of the fin~ers which will be con~
sidered hereinafter. The arrival of the conveyor-chain lug initiates the forward displacement of the rear pair of intercaLary means and the displacement of the front pair of intercalary means in a return movement to a position located upstream of the stacker l. The rear carriage 15, which is placed in this case in front of the front carria~e 16 is associated at this moment with said carriage 16 by means of a latch mechanism. The pair then continues to be moved by the chain to a point down-stream of the stacking head, whereupon a cam releases the latch mechanism and separates the pai.r thus formed. At this moment, the chain lug displaces only the rear carriage of the compartment which has just been formed and brings this latter against the packet which is being unstacked. The yieldable catch-strip 12 constitutes in this case the retractable locking means according to the invention. Stacking of fresh objects can also take place during the same periods since a front intercalary means is then in a wa.ting position downstream of the stacker.
In another mode of operation involving the use of a single chain 17, the chain pushes the entire stock towards the stacker at the unstacking rate. When a newly stacked packet is ready to be directed to the stock, the chain 17 performs one complete cycle. As it passes, the chain places a new front carriage downstream of the stacker, rapidly pushes towards the stock the packet which has just been stacked and, after coming up against the stock, continues to advance at the unstacking rate.
It is preferably ensured in accordance wlth the invention that the number of intercalary means will not be reduced to four but will be substantially greater, in which case the conveying means are arranged differently.
These conveying means are shown in cross-section in Figs. lB

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and lC directly beneath Fig. lA. In Fig. lB which is a top view, the~e can be seen the stacking drum 1 and the unstacking drum lOo There are also shown the thrust-fingers 13 and the retaining-fingers 14, the semicircular cross-section of which indicates that the rounded portions of said fingers are in contact with the objects contained in the compartments. There is also shown a jogging skirt-board 19 located on the left-hand side with respect to the direction of forward motion of the compartments (as indicated by the arrow F). By means of the exploded view of the packets of objects and of the stacking and un-stacking drums, there can be seen a series of five chains designated by the reference numerals 20 to 24. These chains are arranged lengthwise in the direction of forwaxd travel of the packets and are placed next to each other.
Each of these chains is driven by a motor which is in-dependent of the motor of the other chains. Depending on requirements, each chain is provided with one or a plurality of retractable lugs represented by dashes or short lines across the chains in Fig. lB and by small teeth in Fig. lC.
In Fig. lC, the five chains mentioned above are also illustrated but in a side view, that is to say in exactly the same manner as the representation of Fig lA.
An active ~one of these chains is adapted to cooperate with the carriages of the intercalary means. This zone is t located in one plane, namely the plane of the magazine floor 7. For the sake of enhanced clarity of the drawings, these chains have been arbitrarily shown at different levels. It should nevertheless be undexstood that the active top runs of the chains as illustrated could be located in practice at the same level.
It is finally apparent from Fig. lB that each carriage is fitted with at least three catch-strips. In Fig. lB, these catch-strips are represented by dots located in alignment with the fingers 13 or the fingers 1 of each carriage Said catch~strips are represented by short rods in Fig. lC. The catch-strips of row 1 which are designated by the reference 12.1 are adapted to co-operate with the chain 20 or with the chain 21, depending on the position of the carriage within the magazine. The catch-strips of row 2 desiynated by the references 12.2 or 12.3 (depending on whether they are associated respect-ively with a front carriage or with a rear carriage) are adapted to cooperate respectively with the front transfer chain 22 or the rear transfer chain 23. Finally, catch-strips of row 3 designated by the reference 12.4 are adapted to cooperate with the return chain 24. In this embodiment of the intercalary means according to the i~vention, it is therefore observed that these means are provided with a set of fingers 13 or 14 for maintaining the packets of objects, are provided with carriages 15 or .118~

16 which travel on the closed path or circuit 11, and ~re actuated by a set of chains 20 to 24. When so required, said intercalary means produce act:ion on the catch-strips 12.1 to 12.4 located opposite to said chains beneath the carriages 15 or 16. The catch-strips which cooperate with the retractable lugs constitute the retractable locking means according to the invention.
The operation of this complex mechanism is as follows : at the time of stacking of objects in the com-partment which is being formed, the stacking chain 21travels at a speed which is made dependent on the stacking rate and one of the retractable lugs 25 of the chain pushes the catch-strip 12.1 of the front carriage of the compartment which is being formed. When the contents of the compartment are considered sufficient, the return chain 24 fitted with a retractable lug 26 exerts a thrust on the third-row catch-strip 12.4 of the front carriage 16 of the pair consisting of rear carriage and front carriage and located in the waiting position upstream of the stacker. Under the action of its high-speed forward travel, the chain places the above-mentioned pair on the downstream side o the stacker. The front carriage 16 thus placed in position performs the function of a front carriage for a resh compartment whilst the preceding rear carriage has the effect of closi~g the preceding compart-ment.

At this moment, the two rear an~ front transfer chains designated respectively by the references 23 and 22 and each provided with a single retractable lug 27 and 28 respectively engage in the second-row catch-strips 12.3, 12.2 respectively of the packet which has just been com-pletely stacked. In a combined movement of displacement from the stacker to the unstacker, these two chains 22 and 23 hring the above-mentioned packet into position against the existing stock. As they pass by, the first-row strips 12.1 of the carriages of said compartment withdraw the lugs 25 of the chain 21. On completion of this operation, the two chains 22 and 23 carry out a movement which is reverse to the preceding and again come into their waiting positions at the entrance of the stacker 1. They are thus ready to repeat their action for the next compartment.
The fact that the chains are permitted to pass beneath the second-row catch-strip 12.2 of the front carriage which is in the waiting position is made possible by withdrawal of their retractable lugs.
At the time of penetration of the transferred compartment into the storage zone, the front-row catch-strips 12.1 of the front carriage 16 or rear carriage 15 of the compartment 8 withdraw the retractable lugs 29 of the unstacking chain 20. These retractable lugs revert to their upright position as soon as the catch-strips 12.1 have passed. When the transferred compartment comes in~o abutting contact with the stock and the front and rear transfer chains withdraw, the last compartment to be brought is thus processed by the unstacking chain, the last uplifted lugs of which are now maintained respect-ively against the first-row catch-strips of the front carriages 16 or rear carriages 15 of said compartment.
The unstacking chain moves forward at the unstacking rate and is controlled in dependence on this function.
As soon as a pair consisting of rear carriage 15 and front carriage 16 formed by buildup of comparbments within the stock arrives in proximity to the unstacking head at a distance which is equal, for e~ample, to one-tenth of the height of the objects to be stored, a mechanism which will be considered later in the description permits withdrawal of the fingers. The rear-carriage and front-carriage pairs continue, however, to be moved for-wards by the unstacking chain. At the time of formation of a fresh compartment by the stacker, the lug 26 of the return chain 24 can then grip the aforementioned rear-carriage and front-carriage pair on the downstream side of the unstacker in order to recycle it to the stacker.
To summarize, the movements of the chains are as follows : the stacking chain is controlled in dependence on the stacker, the unstacking chain which follows the stacking chain is controlled in dependence on the unstac]cer, and the transfer chains have a seq~ential action in a reciprocating motion which is initialized by formation of a fresh compartment. After positioning of a rear-carriage and front-carriage pair downstream of the stacker, the return chain 24 continues its movement and, by means of its lug 26, is accompanied in its displace-ment by all the pairs of rear carriages and front carriages which have passed beyond the unstacker. To this end, the structure of said chain 24 is such that its active zone is located from the upstream end to the down-stream end of the stac]cer in proximity to the unstackinglocation and on the return path of the circuit 11 which connects the stacker to the unstacker. The last two active zones in any case serve no purpose except in the event that automatic recycling of the carriages is contem-plated. Recycling, however, is not an essential require-ment of the device according to the invention. By means of a test device, the return chain 24 interrupts its action as soon as any one pair reaches the waiting position upstream of the stacker. By way of example, the test can consist of transfer of any one of the catch-strips of one of the carriages of said pair over a pedal 33.2 located upstream of the stacker. During a movement in the opposite direction, said return chain 24 accordingly comes into position upstream of the stacker immediately behind the first pair of carriages in the waiting position. This movement in the opposite direction is made possible by the retractable nature of the lu~ 26.
In the embodiment herein described, the move~
ments of the different motors of the chains will be controlled by a control logic circuit 32 appearing in Fig. 2 and having two actions of different types. The first of these actions consists in determining the thick-ness of the packets to be formed. It was stated earlier that the packet thickness could be fixed beforehand, in which case it is known that this predetermined thickness will be attained when the third-row catch-strip of a front carriage finally passes over a pedal 33.1 as shown in Fig. lB. There is every certainty in such a case that the packets obtained will always have the same thickness. Since the front and rear carriages both have third-row catch-lS strips, it will cle æ ly be necessary to take one item ofinformation out of two. If the thickness of a packet is to be determined by the number of envelopes, the pre-determined positions (185) of a counter 30 associated with the stacker 1 indicate the instant at which the packet is completed. Finally, in the event of random stacking, it may be decided to consider that a packet is any case completed when a predetermined period of time has elapsed after stacking of the last object. This time interval is determined for example by the trailing edge of a pulse delivered by a monostable multivibrator 31 which is excited at each object-stacking operation~

The control logic circuit 32 takes all these indications into account. This circuit producss action first of all on the return chain 24 in order to ensure that it places a rear-carriage and ~ront-carriage pair on the downst~eam side of the stacker and thus to permit formation of a fresh packet. After a time-delay T which has permitted completion of this action, the control cir-cuit initiates startup of the motor of the front transfer chain 22. Then, after a short-time delay ~T with respect to the startup of said motor t the control circuit initiates startup of the motor of the rear transfer chain.
This time-delay ~l is intended to permit the lug 28 of the front transfer chain 22 which is in a waiting position downstream of the stacker to pass across the thickness o~ the packet which has just been formed and even slightly more than this thickness in oxder to produce a slight decompression of the packet which has just been formed. The object of this operation is to facilitate a complementary operation of jogging of packets against the skirtboard 19 during transfer of the packet.
The second operation to be performed by the control logic consists in continuously measuring the position of the rear end of the stock within the storage magazine 2. This position as measured with respect to the upstream end of the unstacking head is a function, at a given instant, o the thickness of the packets brought ., .

into the magazine from the time o-f startup of the machine, reduced by the distance traveled by the unstacking chain from the same instant. The end-of-stock position having thus been determined, the control logic stops the movement of the front transfer chain 22 when it is considered that the lug 28 of said chain has reached this position. The control logic then stops the movement of the rear transfer chain at a slightly later instant in order to ensure re-compression of the packets of objects. The state of compression of the packets can then be equal to or different from the state which existed at the time of formation of the packet. It is preferred in this invention to ensure that all the chain~driving motors are stepping motor~ which actuate the chains in such a manner that a knowledge of the position of the motor entails facto a knowledge of the position of the corresponding chain.
In short, the control logic determines the thick-ness o~ a packet according to the number of steps per~ormed by the motor of the stacking chain from the time of initial formation of said packet. The control logic is informed as to the position of the rear end of the stock prior to arrival of the fresh packet as a result of addition of the thicknesses of the packets which have been stored, reduced by the number of steps performed by the motor of the unstacking chain. The control logic therefore"knows" the number of steps (in principle equal) which the front and rear trans~er-chain motors have to per~orm in oxder to ensure correct stockpiling.
Fig. 2 indicates that the positions of -the chains 20 and 2L are recorded by the control logic 32. Startup of these chains is related to the operation respectively of the stacking drum 1 ox unstacking drum 10.
In regard to the optional recycling operation, the control logic must determine the state of empty carriages available upstream of the stacker. This informa~
tion can be supplied to the control logic, for example by causing a catch-strip of the carriages to pass over a pedal correctly placed upstream of the stacker. By way of example, the passage of a catch-strip 12.3 of a rear carriage over a pedal 33.2 stops the operation of the motor of the chain 24. In this manner r a rear-carriage and front-carriage pair which is available for the formation of a fresh packet is continuously maintained upstream of the stacking head 1.
Suppression o~ the front transfer chain has no effect on the operation of the dynamic storage device according tG the invention. The result thereby achieved is simply to reduce the mechanical operating range thus obtained for the performance of the jogging operation. In the same oxder of ideas, the stacking chain can be dis-pensed with, provided in that case that the stacker is ~, .

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sufficiently powerful to exert a thrust on the packet during formation in order to permit stacking of all the objects. Finally, the rear transfer chain and the return chain can be combined into a single chain, the operation of which would be identical with the chain 17 of the simplified alternative embodiment considered earlier. In tllis case, the control logic is simplified and the un-stacking chain permits uniform unstacking of the objects contained in the packets.
Details relating to the front intercalary means and rear intercalary means will now be studied with reference to the following figures. Figs. 3A, 3B, 3C
represent a first type of the intercalary means under consideration. There can be seen in Fig. 3A the jogging skirtboard 19 2S well as t}le floor 7 of the magazine 2 as shown in cross-section. The intercalary means 6 which is illustrated comprises a carriage 16 and a set of retaining-fingers 14. The carriage 16 travels on the closed path 11 materialized by the roller trac~s 34, 35 and 36 which extend along the entire length of the magazine and on which - the carriage 16 is supported by rollers 37. The arrange-ment of the tracks 3~, 35 and 36 constructed of heavy steel plate, or example, makes i-t possible to prevent side-sway of the carriage as it travels through the entire magazine.
In Fig. 3C, which is a sectional view in a plane 8~

A looking on the top of the carriage 16, it is observed that the carriage has a length, as measured in the direction of displacement indicated by the arrow, of the order of three or four times the diameter of the rollers 37.
In order to prevent pitchiny motion of the carriage during transfer, sets of rollers 37 are mounted both at the front end and at the rear end of said carriage. In Figs. 3A, 3B
and 3C, the carriage is thus provided with twelve rollers.
The retaining-fingers 14 which extend vertically above the carriage advantageously pass through slots formed lengthwise in the floor 7 of the magazine 2 Said retaininy-fingers are attached to the carriage 16 by means of a vertical fork 38 which is maintained within a bore 39 formed in the carriage. By virtue of the thickness of said carriage, the fork 38 is capable of tilting neither backwards nor sideways. In order to avoid rotation of the fork 38 about its own axis, a pivot 40 which is rigidly fixed to the carriage is in~erted within a hole 41 formed in the horizontal return 54 of the fork 38. Said fork 38 is supported by a roller 42 on a roller-track 43 over the full length of the magazine. The roller 42 is brought into contact with the track 43 by means of a spring 44 which is applied on the one hand against the carriage 16 and on the other hand against a flange formed at the lowex end of the fork 38. In a preferred arrange-ment according to the invention, the aforementioned spring 8~

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44 is a helical spring which surrounds the fork 38. In order to complete the remarks made earlier, it should be explained that the roller-track 43 withdraws in proximity to the unstacking head. This makes it possible as a result o expansion of the spring 44 to retract the retaining fingers 14. During this operation, the pivot 40 slides within the hole 41 o the horizontal return 5~.
At the time of positioning of a rear-carriage and front-carriage pai~ of this type on the downstream side of the stackerr it is observed that the fingers of these carriages are parallel to the objects to be stacked. In order to prevent the fingers from sliding between the objects, an ancillary mechanism applies a pallet against these fingers during the stacking of the first objects 1~ which are about ten in number. Said ancillary mechanism then removes the pallet since the rigidity of the ob~ects already in position has become suf-ficient to guide the fresh objects to be stacked. This pallet can consist of a set of two fingers oriented at right angles to the fingers 13 and 14.
There can be seen beneath the carriage 16 two catch-strips which correspond respectively to the catch-strips 12.1 and 12.2 and are potentially useful or the solution in which the transfer means comprise only two chains. These two chains designated hy the reference numerals 20 and 23 are shown in Fig. 3A and are supported `:,' -~3-by roller-tracks 45 and 46. Said chains are provided with retractable lugs 26 or 27 of a type indicated in Fig. 3B In this figure, a rod-shaped lug 27 is mounted by means of an articulation 47 on a link of the chain 23.
Said lug is shown in the retracted position. The movement of the lug 27 is limited on the one hand in one direction by a stop 48 and on the other hand in the other direction by a spring 49 having calculated resilience. In this example, said lug 27 constitutes the retractable locking means according to the invention.
- There is also shown in Fig. 3A a set of rollers 50, 51 and 52 which are inserted so as to project to a slight extent from the floor 7 of the magazine 2, with the result that their generator-line is at a level slightly above said floor. These rollers are placed lengthwise along the magazine 2 and serve for the jogging operation.
The rollers shown in the figure are in fact driven in a movement in the trigonometric direction and have the effect of pushing the stored objects towards the jogging skirt~
board 19. In order to endow this operation with enhanced effectiveness, the rollers 50, 51 and 52 are preferably covered with a layer of rubber or any other material which has comparable friction effects.
Fig. 3C shows that the carriage 16 as illus-trated is a front carriage. In fact, for reasons of overall size, the structure of the carriages considered is , , -judiciously arranged so as to extend beneath the packet which they are designed to convey. Thus in this figure, the carriage which undergoes a displacement in the direction of the arrow comes into contact with a rear carriage, the thrust-fingers 13 of which are shown in dashed lines. The cross-sections of semicircular shape of these fingers exactly complete each other as they come together. This arrangement is made possible by an offset portion 53 of the fingers, this offset portion being per-pendicular to the horizontal return 54 of the fork 38.The o~ientation of the offset portion 53 of the fron~
carriages is contrary to that of the rear carriages. When the hole 39 is located at the mid-length of the carriage 16, the length of said offset portion is equal to the half-length of the carriage. The length of the carriaye is the dimension of this latter as measurea in the direction of longitudinal displacement.
Figs. 4A and 4B illustrate ano~her example of construction of a carriage. The essential feature of this example lies in the fact that the roller-track followèd by the front carriages as they travel on the circuit 11 is different from the roller-track followed by the rear carriages. In Fig. 4B r the front carriages 16 travel in the direction of the arrow along the roller-track 5~
located on the left-hand side of the figure whilst the rear carriages 15 travel in the same direction along the -` ~2~

roller-track 55 located on the right-hand side of -the figure. The roller-tracks 55 and 56 which suppor-t the carriages essentially comprise in each case two solid runways 57 and 58 which extend in a plane paralle] to -the plane of the magazine floor 7. The two runways 57 and 58 of one roller-track are rigidly coupled together by means of a flat arch 59.
In the example shown, the carriages are provided with a T-section support member 60 which extends vertically above the carriages and fits exactly within the space provided between the runways 57 and 58 and the flat arch 59. The ends of the horizontal arms of the T-section support members are fitted with rollers or needle bearings 61. These bearings 61 are applied against the runways 57 and 58 when a carriage is traveling during transfer of a packet. Said needle-bearings serve to support the carriage 16. In a comparable manner, the central mast of the T-section support member 60 is located between two needle-bearings 62 which are applied against the oppositely-facing vertical side-walls of the runways 57 and 58.
It is apparent from a study of Fig. 4B that the bearings 61 and 6~ are doubled so as to form two sets located respectively in front of and behind the carriage considered. The bearings 61 have the design func~ion of preventing either side-sway or pitching movements of the 8~

carriage whilst the bearings 62 are intended to prevent crabbing displacement of the carriage with respect to the direction of forward travel within the magazine 2. In fact, the running clearance provided for the bearings 5 within the space contained in the roller-tracks 55 or 56 is reduced to a minimum.
The carriages 15 and 16 thus travel along the roller-tracks 55 and 56 respectively which are located side by side. Each carriage is provided with a horizontal cross-member designated respectively by the reference numerals 63 and 66~ The cross-members extend over part of the channel located between the roller-tracks and serve to fix hollow posts designated respectively by the refexence numerals 64/ 65 and 67/ 68~ The hollow posts are oriented at right angles to the magazine floor 7 and are pr~vided with bores which-extend vertically within said posts from one end to the other in order to serve as guides respectively for the fingers 13 or 1~ of the carriages aforesaid. From the cross-sectional view of the posts 63 and 66 and of the posts 64/ 65 and 67/ 68/
taker. in a plane parallel to the plane of the support floor 7, it is apparent that the fingers 14 will lie in the same plane as the fingers 13 as a result of an e~f~ct of interengagement (as shown in Fig. 4B)o In consequence, the interval between two juxtaposed compartments in the storage line will be equal solely to the diameter of said L8~

fingers 13 or 14.
The justification for the existence of these two roller-tracks 55 and 56 lies in the need to set up effective resistance to pitching motion of the carriayes.
Under the action of mechanical motion, this resistance is directly rela~ed to the length of the carriages. In respect of a given packet length, it has been established that the length of the carriages of Fig. 4A can thus be double the length of the carriages of Fig. 3A. The length of each of these carriages can in fact be equal to the total length of the packet whereas, in the previous instance, it could be equal only to one-half the total length of the packet.
Finally, there can be seen beneath the carriages 15 and 16 a set of toothed wheels 68.1, 68.3 for the rear carriages 15, and a set of toothed wheels 68.1, 68.2 for the front carriages 16. These toothed wheels are such that, by means of a ratchet system, they are permitted to rotate freely only in one direction with respect to their axis but are prevented from rotating in the other direction. In this application, the chains 20, 21, 22 and 23 fitted with ret~actable lugs will be replaced by sprocket chains or slotted drive-belts. These slotted drive-belts are adapted to cooperate with the correspond-ing toothed wheels in accordance with the foregoingdescription. The "free-wheel" motion of these toothed . .

wheels is indicated on the assumption that the carriages are moving away from the person who is lookiny at Fig. 4A.
During the transfer stage, the toothed wheels 68.1 travel on the double sprocket chain 20 used for the unstacking operationO In consequence, the top of the toothed wheel 68.1 moves away from the observer while the center of rolling motion is stationary. This arrangement is indicated by a cross contained within a circle represent-ing in schematic form the feathering of an arrow which is traveling away from the observer. Similarly, it is shown that, under the action of the return motion of the transfer chains 22 and 23, the toothed wheels 68.2, 68.3 have a degree of freedom in the same direction as the toothed wheels 68.1.
The return chain 24 is also replaced by a slotted drive-belt. The position of this slotted drive-belt is such that it comes into engagement for e~ample with the toothed wheel 68.2 of the front carriage 16~ At the same time, the drive-belt produces a for~ard displace-ment of a rear-carriage and ront-carriage pair at the time of operations which involve positioning of a fresh carriage pair for stacking or at the time of recycling of a carriage pair after unstacking.
The fingers 14 and 13 which slide respecti~ely within the bores of the posts 67, 68 or 64, 65 are pro-vided at their lower ends with shoes 70 and ~9 L8~

respectively. These shoes are advan-tageously capable of sliding within a slide-block 71 provided with two recesses 72 and 73. The top edges of said recesses are bent inwaxds so as to form flanges 74. By bearing on the shoes 69 or 70, these top flanges have the effect of maintaining the shoes 69 or 70 at the bottom of the recesses 72 or 73. In order to cause withdrawal of the fingers 13 or 14 in proximity to the unstacking head 2, the slide-block 71 undergoes a do~nward displacement with respect to the plane of the magazine floor 7. The amplitude of this downward displacement is slightly greater than the apparent height of the fingers 13 or 14 above the floor 7.
By reason of the presence of the flanses 7~ at the time of forward displacement of the carriage 15 or of the carriage 16, said flanges bear on the shoes 69 or 70 and thus cause the fingers to move downwards. The downwardly displaced position of the slide-block 71 is shown in dashed outline in Fig. 4A.
Fig. 5 illustrates another example of con-struction of ~he retractable fingers. The carriage shown in this figure is identical with the carriage of Fig. 3~.
In this example of construction, the fingers have the general shape of a scythe-blade comprising a handle 75 which ~xtends upwards from the carriage 15 to the magazine floor 7 at a predetermined angle of slope. The fingers consist of two flat blades 76 and 77 forming segments of a : .

~o-circular riny whose center coincides with the pivo-t point 0 of the handle 75. The two f]at blades 76 and 77 penetrate into the magazine through two slits designated respectively by the reference numerals 78 and 79 and formed longitudinally in the jogging skirtboard 19. When the carriage moves, the objects placed on the support floor 7 against the jogging skirtboard 19 are thus thrust by the blades 76 and 77 in a direction at right angles to the plane of the figure.
The retractable fingers are held in position along the entire length of the magaæine as a result of sliding displacement of the handle 75 along a guide rail 80. Contact is maintained between the guide rail 80 and the handle 75 by means of a roller~bearing 81 which is press fitted around the handle 75 and is adapted to run along the guide rail 80. By virtue of its weight, said roller-bearing also assists in maintaining the handle 75 in an inclined position. The guide rail 80 is cut in the immediate vicinity of the unstacking head. At this point and under the action of their weight, the handle 75 and the blades 76 and 77 undergo a pivotal displacement about an axis which is perpendicular to the plane of the figure and passes through the point 0. It is noted that, in this configuration as in the preceding configurations, ~5 withdrawal of the fingers always takes place in a direction parallel to their own axes.

One example of an object 3 having a height h is illustrated in ~ig. 5 in the ~orm of a ].etter or envelope.
The objects are not liable to be disturbed at the time of withdrawal of the fingers since they are continuously held in position by the jogging skirtboard l9 and by the magazine floor 7. In fact, since these objects such as envelopes are placed at right angles to the direction of the longitudinal slits 78, 79, they cannot possibly pass through these slits~ This arrangement is an advantageous feature of the carriages since it guards against any potential danger of misalignment of envelopes.
Fig. 6 is a sectional view showing the preferred embodiment of carriages in accordance with the invention.
As in ~ig. 5 r the intercalary means in this instance comprise fingers composed of flat blades 76 and 77 which pass through slits 78 and 79 formed in the skirtboard 19 and joined to a handle. The handle has the shape of two vertical se~ments 80 and 81 joined together by a hori-zontal portion 82. The carriage proper has the shape of a rectangular parallelepiped having an approximately square section. As in the preceding examples, a set of pins extending at right angles to the faces o~ said rectangular parallelepiped are inserted within the interior of rollers or needle-bearings 83 or 84.
The roller-track of the carriage as thus con-structed has a complex shape. In two parallel horizontal ~32-portions 86 and 87 located in oppositely-facing relation, there is formed in each case a pair of grooves 88 and 89 which serves as a longitudinal housing for the rollers 83.
The two horizontal portions 86 and 87 are joined together along one side by a vertical portion 90 which is per-pendicular to these latter. A groove 91 is formed in said vertical portion 90 and serves as a housing for bearings 84. In a position opposite to the portion 90 with respect to the parallelepipedal carriage, there is fixed a vertical portion 92 which is joined to the horizontal portion 87 but not to the horizontal portion 86. There is formed in said vertical portion 92 a groove 93 which is intended to serve as a housing for a needle-bearing located opposite to the bearing 84.
The guide rail thus formed for the roller-track of the carriage of parallelepipedal shape has a longi-t~ldinal clearance space 94 which permits the permanent attachment of the vertical segment 81 to the parallele-pipedal carriage. Along the length of this parallele-

2~ pipedal carriage as measured in the direction of its dis-placement and ~s mentioned earlier with reference to Fig. 3C, provision will be made for two sets of rollers ~3, 8~ in order to guard against pitching, side-sway and pivotal displacement of the carriage. The carriage is therefore provided in this case with eight rollers.
The guide rail hereinabove described terminates 31 2~

~33-upstream of the unstac~ing head in a rotary barrel unit 95 constituted by a disk 96 on which are ~ixed at right angles a plurality of identical elements 97 having a sufficient length and the same cross-section as the guide rail. The length of said elements is slightly greater than double the len~th of one of the parallelepipedal carriages.
If the carriages are capable of interengagement in the same manner as the horizontal cross-members 63 and 66, this length is less than double the length of one oE the carriages. In the example provided, said guide-rail elements are four in number but it will be understood that provision could be made for a different number. The operation of the rotary barrel unit will now be explained.
When a rear-carriage and front-carriage pair thus arrives in close proximity to the unstacker, it engages in a guide-rail element 97 which is rigidly fixed to the rotary barrel unit and forms an extension of the roller-track.
end-of-travel detector or alternatively the control logic initiates a movement o~ rotation of the barrel uni 95 by means of a motor ~not shown in the drawings). This move-ment of rotation takes place through a predetermined angle in such a manner as to ensure that another vacant guide-rail element is placed in the line of extension of the roller-track 86 to 94. In the example considered, this angle is 90.
At this moment, the pair of carriages which has been rotated is located opposite to a return roller-track so as to permit recycling of the carriages to the stacker It is apparent from a study of the figure that the functions of the rollers 83 and 8~ have been reversed and that the rollers 83 now serve to support the carriages. It is observed that the blades 76 and 77 have been withdrawn from their position as a result of rotation of the disk 96 about its center 0 and that said blades consequently no longer interfere with the operation which involves unstack-ing of objects of the following packet. Since the carriagewhich has just been reversed is taken away by the return chain 24, it is possible to design a rotary barrel unit 95 provided with only one guide-rail element 97. After removal of the reversed pair of carriages, the rotary barrel unit returns to its position opposite to the roller-track. By extension, in consideration of the fact that the radius of rotation of the barrel unit is of substantial length, the movement which is imparted to the carriage by said unit becomes a movement of translation. In this case, the blades 76 and 77 are straight.
As in the case of Fig. lC, the conveying means of the preferred alternative embodiment of the invention comprises a set of five chains. The sectional view of Fig. 6 shows a pair of carriages in proximity to the un-stacking head. A lug 29 of the unstac~ing chain 20 isapplied against a first-row catch-strip 12.1 of the ..

~21~7 . -35-carriaye illustrated in order to constrain said carriage to move towards the observer who is looking at the figure.
It is se.en that the front transfer chain 22 and rear trans-fer chain 23 respectively located opposite to the second-row catch~strips 12.2 and 12.3 do not cooperate at thismoment with these catch-strips since they are now in the waiting position at the stacking head and their lugs 28 and 27 are no-t visible~ The action of the return chain 24 consists in pushing forward a pair of front and rear carriages which has just been reversed by applying its lug 26 against the catch-strip 12.2 which, as has been noted earlier, performs the function of a third-row catch-strip 12.4. However, if this had been made necessary by condi-tions of limited space, it would have been possible to form a third-row catch-strip 12.~ specifically installed or the purpose of cooperating with the return chain 24. This return chain 24 produces a movement of the carriages in a direction parallel but opposite to those of the other our chains although the axis of rotation of the drive motor of said return chain is located in a plane parallel to the floor 7 whereas the axes of rotation of the motors which drive the other chains are perpendicular to said floor 7.
Since the rotary barrel unit described in the foregoing is located in proximity to the unstacking head, the invention proposes to instal a barrel unit of the same type upstream of the active generator-line of the stac~ing head. The sequence followed b~ the rear-carriaye and ront-carriage pairs is the same but reverse to the sequence just described. In the proximity of the stacker 1, the unstack-ing chain 20 is replaced by the stacking chain 21 which inany case cooperates with the front row catch-strip 12.1.
The stacking barrel unit will be judiciously placed in such a manner as ~o ensure that the blades 76 and 77 are placed respectively above and beneath the active portion of the stacking drum 1 but slightly set back with respect to the generator-line o~ this drum which is in contact with the packet as this latter is being stacked.
Figs. 7A and 7B are flow diagrams of the transfer function which is governed by the control logic 32. The operational se~uence shown is the preferred case of the invention and relates to an embodiment involving the use of rotary barrel units and in which the return of the carriages is arranged on a so-called rectangular circuit.
In this circuit~ the carriages undergo backward return movements in contrast to carousel circuits in which the carriages always travel back and forth in the same direction.
The flow diagram of Fig. 7A relates to the stacking stage. The two tests which are present at the start of the flow diagram are performed cyclically by the control logic. These two tests serve to determine the state of the active or non-active stackiny drum and the thickness of the packet of objects being formed. If the drum is active and if the thickness of the packet within the drum is between a minimum length and a maximum length of predetermined value (for example between 75 mm and 150 mm)l it is necessary to close the packet in process of formation by introducing a rear intercalary means and to begin a fresh compartment b~ introducing a front inter~
calary means. This is obtained by causing the stackin~
barrel unit to rotate by one step.
Control of rotation of the barrel unit will take place in a preferred manner in accordance with a law of motion which ensures a correct rendezvous between the retaining fingers and the letters which arrive at the stacker. Initialization of this control operation is produced by a sensor which detects the passage of the trailing edge of the last envelope to be stacked. Intro-duction of the new fingers takes place with a calculated and constant time-lead with respect to the arrival of the followin~ object.
For reasons mentioned earlier in connection with the correct alignment of envelopes contained in the magazine, startup of the front transfer chain will -take place at an instan~ which allows a predetermined length of time to elapse prior to startup o~ the rear transfer chain. This time interval will be determined experiment-ally. The time-delay governing startup of the rear transfer chain with respect to the front transfer chain may depend on the thickness of the packet to be formed and on the logical possibilities of the control logic.
Stopping of the transfer chains can be produced by an end-of-travel contact. By way of example, this end-of-travel contac~ can comprise a pedal installed on the front transfer chain and adapted to come into abutting contact at a suitable point with the structure of a rear transfer carriage at the time of encounter of these two carriages within the storage magazine. Since the pedal constitutes a switch, it usefully establishes a contact between two flexible wires which terminate at the control logic~ Said end-of-travel contact can also be obtained by means of a device for measuring overvoltage at the terminals of the drive motors of the front transfer chains and rear transfer chains as the conveyed compartment comes up against the existing stock. In fact, the variations in the voltage-current characteristics of these motors can be utilized to advantage in this manner. The order pro-duced at this moment by the control logic initiates the return of the transfer chains to their position upstream of the stacking head.
Fig. 7~ shows the flow diagram corresponding to the unstacking operation. When the unstacking barrel unit is active, and when a rear-carriage and front-carriage ~2~ 7 pair penetrates into said barrel un~it, and when finally there is no front-carriage and rear-carriage pair in the bottom position of the barrel unit corresponding to standby for recycling, forward displacement of the magazine is then stopped for a period of time of predetermined duration. This time interval serves to inhibit magazine advance during the period of disengagement of the fingers of the carriages and is initialized by control of the jack which rotates the barrel unit. The unstacking operation is then reswmed whilst the return chain 24 takes the pair of carriages which has thus been placed on the return track in order to direct this pair to the stacker.
It is wholly apparent that all these mechanical operations take place with time-seLtings which are adjusted experimentally. The position detectors which are necessary for the ope~ation of the device according to -the invention are of a type which is known to those versed in the art and can comprise in particular photoelectric cells. For example, the unstacking procedure will be initiated only at the instant of occultation of a cell which controls the forward displacement of the magazine.
Rotation of the barrel unit is permitted only when a cell has confirmed the real presence of a carriage pair within the barrel unit. Finally, the control logic is controlled by a clock, the frequency of which is higher than the rate of operation of the stacker or of the unstacker.

Claims (11)

WHAT IS CLAIMED IS :

1. A device for dynamic storage of flat objects comprising a stacker for placing all the objects to be stored on edge against each other and within a storage magazine provided with successive compartments delimited by intercalary means, said intercalary means being dis-placed by conveying means, and an unstacker for withdrawing the objects stored in the compartments, wherein the stacker and unstacker are stationary, and wherein the intercalary means are independent of the conveying means and are caused to cooperate in pairs with said conveying means by retractable locking means in order to form each time the front and rear ends of one compartment and in order to transport a corresponding packet of objects along the magazine towards the unstacker.

2. A storage device according to claim 1, wherein the intercalary means comprise carriages supported by a circuit which extends along the magazine next to the conveying means and wherein the carriages are provided with fingers for guiding the objects while they are being transported.

3. A storage device according to claim 2, wherein the fingers of the carriages are retractable in a direction parallel to their axes through an alignment face at the time of operations involving delivery of a packet of objects to the unstacker and in a direction which prevents any danger of misalignment.

4. A storage device according to claim 3, wherein the conveying means comprise at least one chain for co-operating in only one direction with a catch-strip of the rear intercalary means of the compartments.

5. A storage device according to claim 4, wherein the conveying means comprise at least two chains consisting of a transfer chain according to claim 4 and an unstacking chain, the rate of travel of said unstacking chain being controlled in dependence on the rate of travel of the unstacker and provided with a plurality of retractable lugs so as to form retractable locking means in conjunction with stationary catch-strips which are rigidly fixed to each intercalary means.

6. A storage device according to claim 5, wherein the conveying means comprise at least four chains adapted to cooperate with a set of catch-strips in juxtaposed relation and fixed on the intercalary means, preferably a set of ratchet wheels in order to form at least three separate and distinct retractable locking means, and comprising :
- a first stacking chain adapted to cooperate with a first catch-strip, - a second front transfer chain adapted to cooperate with a front transfer catch-strip, - a third rear transfer chain adapted to cooperate with a rear transfer catch-strip ;
- a fourth unstacking chain adapted to cooperate with the first catch-strip.

7. A storage device according to claim 2 or claim 6, wherein the circuit forms a closed loop and wherein a fifth return chain is adapted to cooperate with one of the catch-strips in order to permit recycling within the device of a pair of front and rear intercalary means.

8. A storage device according to claim 2 wherein the circuit comprises two segments whose ends terminate opposite to two rotary barrel units which permit transfer of the carriages from one segment to the other by sliding and wherein the fifth chain is adapted to co-operate with one of the catch-strips in order to carry out recycling of the transferred carriages.

9. A device according to claim 8, wherein the cir-cuit comprises two roller-tracks on which the front carriages or rear carriages are intended to travel.

10. A device according to claim 9, wherein the retractable locking means comprise mechanical lugs held in position against a stop by resilient means in order to produce action in a given direction and in order to slide in another direction without jamming.

11. A device according to claim 9, wherein the retractable locking means comprise ratchet-type toothed wheels which are adapted to cooperate with slotted drive-belts.