GB2063828A - Improvements in or relating to stacking methods and devices for the production of wafer blocks - Google Patents

Abstract

A device for forming wafer blocks has a feed conveyor 1 for feeding wafer leaves in succession to stop surfaces 22, and a lifting conveyor 2 comprising spaced rotatable wheels 2b having angularly spaced fingers 9 for raising the leaves into a stack, for eventual removal by a withdrawal conveyor 3,7 at a speed independent of the lifting speed and the feed speed, in a plane spaced from the feed plane. A programmed timing device may control the various movements. The withdrawal conveyor comprises pushers 5 and conveyor belts 7. The pushers 5 coact with stops 20 to provide the stop surfaces 22. <IMAGE>

Description

SPECIFICATION Improvements in or relating to methods and devices for the production of wafer blocks The invention relates to methods and devices for the production of wafer blocks.

German Offenlegungschrift (DE OS) No.2323646 describes a device for the production of wafer blocks using a method for the production of wafer blocks consisting of at least one wafer leaf provided with a filling layer and one wafer cover leaf, in which method these wafer leaves, which are provided with or without filling layers, are successively joined by * means of respective forcibly conducted movement at a speed that is independent of their delivery speed to a predetermined starting position for the joining to the desired wafer block in a direction that is virtually vertical to their delivery direction so as to form the desired wafer block, which is then trans ported away from its joining position in order to clear this position for the next following wafer block or the first wafer leaf thereof.

The individual wafer leaves to be joined so as to form the desired wafer block are successively fed by means of a feeding conveyor to a predetermined starting position, which is defined by a stop which is withdrawable to the top from the conveying path of this conveyor, for their joining so as to form the desired wafer block, while the wafer cover leaf or the partial wafer block already formed is held in a raised position by means of lifting fingers which engage therebeneath and which are provided on a lifting star wheel so that the following wafer leaf provided with a filling layer can be conveyed to its predetermined starting position, whereupon there is then formed, by the lowering of the wafer cover leaf or the partial wafer block already formed on the filling-coated wafer leaf waiting in this starting position, a wafer block which is thicker by one additional wafer leaf layer.

Practical experience during the operation of this known device has shown that the throughput rate of wafer leaves and, depending thereon, the block formation capacity per unit of time cannot be increased beyond a specific limit, this limit for the maximum wafer leaf throughput per unit of time that is possible moving the more in the downward direction the gentler the wafer leaves to be handled have to be treated.And in this connection there arises a special problem in modern wafer production, since it is necessary to handle wafer leaves whose surface gets larger and larger and to join them to wafer blocks and, at the same time, to satisfy the further requirement that, in accordance with the prevailing taste, the wafer blocks should be formed with an ever increasing number of wafer layers and filling material layers located therebetween; in addition, it is often desired that the thickness of the filling layer should be increased. From the two aspects there thus arises the problem of having to handle, for a predetermined wafer block total thickness with a predetermined wafer leaf orfilling layer number and possibly also a desired filling layer thickness, wafer leaves whose own thickness is extremely small.Frequently, another point that has to be considered in this regard is the fact that, for example on account of what is fancied with respect to taste, these wafer leaves may in their baked state consist of relatively crisp or fragile material. Nevertheless, for reasons of rational production with the lowest possible expenditure for installation and operating costs and thus as far-reaching a reduction of the cost of production of the finished wafer end products as possible and, as a precondition therefor, of the wafer blocks to be formed, it is desirable, despite the afore-described difficulties, to be able to handle and join to the desired wafer block wafer leaves of the largest possible size with or without filling layers and irrespective of their thickness, consistency and weight reliably and free of any risk of damage as well as to the largest possible extent free of contaminants which, on the one hand, reduce the quality of the wafer block formed and, on the other hand, impair the trouble-free and smooth continuous working sequence of the device for the production of the wafer blocks and thus may lead to considerable costs in connection with the rectification of such malfunctions and, associated therewith, to servicing and the like.

It is however not only these difficulties which have to be overcome in order to bring about an increase in the wafer block formation capacity. Further limits to an increase in output also result from the kinematic conditions of the block formation method which, for the rest, depend very considerably on the conception of the known device. Since the completed wafer block is transported away by means of the same conveyor which delivers the wafer leaves to be joined to the desired wafer block, it is necessary, prior to the delivery of the first wafer leaf of the next wafer block to be formed, to remove the wafer block formed from its lowered position, which was necessary for the block formation, so as to clear this position for the next wafer blade. However, this necessitates that the delivery operation occurs at the same speed as the removal operation of the completed wafer block.Therefore, an increase in the throughput rate could here only be brought about by an increase in the delivery speed, which corresponds to the removal speed. However, limits are set to this speed in other ways.

Although it is desirable that the wafer leaves should reach their position of joining as quickly as possible, it is imperative, particularly if wafer leaves are involved which are of large size and/or particularly thin and/or are provided with thick and/or heavy filling layers, that these should be braked as gently as possible, that is to say the time speed pattern of their delivery speed should be flat at the moment when they enter their position of joining.For the wafer leaves, which have a considerable inert mass on account of their large-surface formation and/or the type of their filling layers, must be prevented from bouncing with too much force on the stop, which defines their position of joining, in the path of the delivery conveyor, which may lead to damage to the mostly rather fragile wafer leaf front edge, thus causing not only the entire wafer block concerned to become unusable but also dreaded operating troubles to arise involving idle time losses in the production sequence with undesirable cost consequences.For this reason, the feeding conveyor has to be operated at a constant speed, which must however not be too high, so as to avoid harmful impact impulses on the stop in the delivery path of the delivered wafer leaves or there has to be observed a suitable speed program for the feeding conveyor which ensures that despite a high initial speed, in any event at the time when the starting position defined by the stop in the delivery path is reached, for the joining to the desired wafer block, the delivery speed is sufficiently low.However, the latter possibility necessitates a control expenditure that is not inconsiderable, since the feeding conveyor and the withdrawal conveyor of this known device are formed by the same conveyor and it is therefore necessary to handle masses which are not inconsiderable, also with respect to the removal of the wafer block, whose weight is considerably higher and which may consist of many layers, with corresponding delays and accelerations.

Yet another factor prevents an increase in the throughput rate. For a minimum spacing between the individual wafer leaves delivered is necessary in order to ensure that, following the formation of the finished wafer block and the removal thereof, there is left sufficient time for lowering again the stop which is necessary for limiting the feed movement of the following wafer block or its first wafer leaf during the feeding conveyor delivery movement which is continued for the onward transportation of the complete wafer block. However, this necessitates an adequate pulling-apart of the individual wafer leaves to be delivered prior to their entering the position of joining.But this time span is the same for all delivered wafer leaves, although it is only required between the last wafer leaf of the completed wafer block to be transported away and the first wafer leaf of the next wafer block. The disadvantage resulting therefrom is an enforced sequence of idle-time periods, which is an insurmountable limit to a further increase of the throughput rate.

It is also impossible to bring about a gain of time by operating the lifting conveyor, which is formed by the lifting star wheel with its lifting fingers, at a greater rotational speed. For, during the process of lowering the completed wafer block, this block impinges on the withdrawal conveyor at maximum speed in the direction that is vertical to the removal plane. It is to be feared that there will occur vibrations and a relatively hard superimposition on the conveyor and, if the latter is constructed with sufficient elasticity, torsion and twist phenomena in the completed wafer block which, particularly if especially large-sized and or especially thin and/or especially muiti-layered wafer blocks are involved, may lead to cracks, at least in the outside wafer leaves, which cause the whole wafer block to be rejected.An increase in the operating speed of the lifting conveyor would lead to particularly unfavourable stress conditions here because the lifting speed follows a sine function in the direction that is vertical to the wafer leaf plane and during the lowering operation, during which the self weight additionally has an accelerating effect, the speed course is in the steep leg of the sine curve and the lowering speed therefore has its maximum value which must be braked so that, despite the impact impulse of the wafer leaf or the formed partial wafer block on the filling-coated wafer leaf located therebeneath, any risk of damage to the latter is reliably avoided.

However, in practice, this can only be achieved if the rotational speed of the lifting conveyor is kept below certain limits.

Another related device is that of DE OS 2 809 642.

This known device layers wafer leaves, which are provided with filling coatings, from the bottom against a wafer cover leaf or preceding filling-coated wafer leaves which have been formed into a partial wafer block and comprises for this purpose a lifting conveyor which is formed by two conveying screws which are provided laterally of the conveying track of a feeding conveyor, by means of which the wafer leaves to be joined to the desired wafer block are delivered, and which rotate in opposite senses about a vertical axis. The wafer leaves which have been taken to the range of action of the lifting conveyor screws and which have or are without filling layers are brought to the lifting speed in the lift direction without any positive limitation of their speed in the direction of delivery.The rotational speed of the conveyor screws, and thus also the lifting speed of the wafer leaves conveyed by the lifting conveyor, is constant. To allow them to undergo an ascending process in the windings of the conveyor screws, there is provided a stop for the lifted wafer leaves.

Until such time as this stop is removed, the delivered wafer leaves stay in the uppermost flattened windings of the conveyor screws and the subsequently delivered wafer leaves are joined beneath the preceding wafer leaves. Following the lifting and joining of the desired number of wafer leaves, the stop is then removed, which causes the formed wafer block to be transported away merely by the continued rotational movement of the conveyor screws. The lifting conveyor of this known device thus simultaneously is the withdrawal conveyor, by means of which the completed wafer blocks are moved from their position of joining to a transfer position for an onward conveyor arranged downstream thereof.

This known device is also incapable of meeting the requirements of modern high-capacity wafer block production for the reasons described hereinafter.

On the one hand, the engagement of the lifting members formed by the conveyor screws in the wafer leaf with or without a filling layer is necessary always effected in a punctiform manner, due to the punctiform interesection of the plane of the wafer leaf with the respective cochleoid. As a result, the wafer leaf to be lifted is always only punctiformly supported, which in itself is a relatively unfavourable method of introducing the lifting force into the water leaf but has a particularly unfavourable effect if the respective wafer leaf is particularly ?-ge-sized and/ or thin and/or crisp or fragile and/or is provided with a thick andlor heavy filling layer.The risk of edge damage to the wafer to the wafer leaf involving the dreaded operating troubles caused by rejects and contamination of the entire device is further in creased by the fact that when entering the lifting conveyor of this known device, the wafer leaves are not braked so as to come to a standstill or almost a standstill in the direction of delivery and are then subjected to the action of the lifting force but that their movement is suddenly deflected from the delivery direction to the lifting direction.Of course, this leads to extreme mechanical loading of the wafer leaf material at the deflection point in time, the more so since the fact that, due to the conception of the lifting conveyor of the known device, the suddenly arising lifting force introduction into the wafer leaf, which has been delivered by means of the planar delivery force application, is effected in a punctiform manner is an additional disadvantage.

This risk of break-outs and the links from the wafer leaf material, with a corresponding contamination of the known device and the dreaded breakdowns associated therewith, is increased even further if the lifting conveyor screws are operated faster for the purpose of increasing the throughput rate of the wafer leaves. Here, an insurmountable limit is set to an arbitrary increase of the lifting speed by the mechanical loadability of the wafer leaves to be lifted and to be joined so as to form the desired wafer block.

On account of the specific conception of this known device, the effect of this limit is however also felt in a different direction. Since the seating of the wafer leaves has to be effected at as low a speed as possible for mechanical reasons, particularly in view of the risk of damage to the wafer block to be formed and in the interests of as trouble-free a production sequence as possible, but since, on the hand, the coating speed necessarily corresponds to the constant lifting speed and the speed of transporting the completed wafer block away is in turn directly dependent on this latter, since the lifting conveyor simultaneously is the withdrawal conveyor, an increase of the wafer block formation capacity to values which satisfy modern requirements is virtually impossible, quite apart from the fact that even an increase in the delivery speed of the wafer leaves to the lifting conveyor cannot, for reasons of the principle of the procedural and constructional conception of this known device, contribute to an increase in output since the bottle-neck for an increase of the throughput rate lies in the illustrated limitation of the lifting speed and the removal speed of the formed wafer block which is directly dependent on this lifting speed.

Furthermore, the lifting speed of the lifting con veyorofthis known device has to be so adapted that the formed wafer block which is removed from its position of joining by the horizontal component of the conveyor screw movement on account of friction contact has sufficient time for leaving this position of joining for the first wafer leaf of the next wafer block.

In contrast to the known device described first, the delivery of this first wafer leaf of the next wafer block by the lifting conveyor at a constant lifting speed is herein effected simultaneously with the removal of the preceding completed wafer block, which removal also occurs at a constant withdrawal speed that is dependent on the lifting speed. Any intended variation of the two conveyor movements relative to each other is in principle impossible. However, experience has shown that such a variation does occur in an undesirable manner during the operation of this known device.Due to the contamination of the screw tracks which is unavoidable in this device and is caused by wafer leaf abrasion and filling layer residues, non-defined ratios of friction come about, particularly in the contact zone of the lowest wafer leaf of the completed wafer block, on the uppermost flattened screw windings of the two conveyor screws of the lifting conveyor. For this known device is so designed that its screw spirais are cleaned unaidedly by their movement relative to the wafer leaves conveyed by them.However, this means that the scraps adhering to them during their lifting operation adhere not only to the wafer leaf and by contamination of the visible surface of the respective wafer leaf lead to an undesirable unsightly appearance and thus to a loss in quality of the wafer block but, on the one hand, are dragged along on the underside of the respective wafer leaf and, on the other hand, are lifted upwards by the wafer leaf edges from wafer leaf to wafer leaf on the screw spirals and, in both cases, accumulate in the contact zone of the uppermost screw windings with the lowest wafer leaf of each wafer block.This causes such undefined ratios of the friction contact in the lifting conveyor zone which forms the withdrawal conveyor that of necessity two further measures which run counter to an increase in the throughput rate have to be taken: On account of these undefined ratios of friction, a specific minimum time with a corresponding margin of safety has to be made available for the removal of the completed wafer block so as to ensure in any event that the formed wafer block to be removed has always left its position of joining before the first wafer leaf of the next wafer block, which follows at the same spacing and the same lifting speed, has reached this position of joining.However, for this purpose, a sufficiently flat pitch has to be chosen for the conveyor screws so as to allow, at a constant conveying speed for the following first wafer leaf of the next wafer block, the preceding formed wafer block sufficient time for its removal, or else the rotational speed of the lifting conveyor screws has to be reduced accordingly. In the first case, there inevitably results a slowing-down of the entire wafer block formation process because all that would be desirable for the slowing-down of the feed movement of the first wafer leaf of the next wafer block affects in an undesirable manner the conveyance of the other wafer leaves which are to be joined for the formation of the desired wafer block. In the second case, a slowing-down of the rotational movement of the conveyor screws of the lifting conveyor also leads to a reduction of the horizontal component of the screw movement and thus to a reduction of the removal speed for the completed wafer block. Both measures thus stand counter to an increase in the throughput performance. In addition, a certain time interval between the formed wafer block that runs away and the first wafer leaf of the next wafer block that runs into the position of joining has additionally to be observed so as to allow the limiting stop for defining this position of joining to be taken in time to its working position.This, in turn, is only possible by a corresponding reduction of the screw pitch from its value that is theoretically maximally admissible for other reasons, which has however a negative effect on the block formation time for the entire block formation cycle.

This has been realised in connection with this known device. In order to remedy at least the unfavourable conditions with respect to time and conveying rate, which result from the undefined ratios of friction, there are provided additional auxiliary conveying means in the form of withdrawal belts and guide rollers which require scrapers for the filling layer compound and are independently driven and are to ensure the reliable removable of the completed wafer block. These measures necessitate an additional expenditure of construction of costs and are an additional source of fault with an increased maintenance requirement, but cannot eliminate the basic restrictions already described for an increase in the wafer block formation output per unit of time, which result from the procedural and constructional conception of this known device.

Apart from the dead times which must always be kept available, by reason of the removal paths which differ, as experience has shown, from wafer block to wafer block on account of the different ratios of friction and the fluctuating removal speeds, and which, as described stand counter to an increase in the throughput rate, these different ratios of friction have another disadvantageous effect on this known device. For, in practical operation, it would seem unavoidable that such differences in the ratios of friction come about not only over the length of the formed wafer block in the removal direction but also with respect to the zones of contact of both lifting conveyor screws with the lowest wafer leaf of the wafer block.This entails the risk of the completed wafer block being twisted and damaged even if, for the compensation of the differences in the frictional contact ratios, there are provided over the length thereof auxiliary conveying means in the form of withdrawal belts and guide rollers or the like.

It has furthermore proved to be disadvantageous that, for example in the case of unfavourable weight ratios of the formed wafer block and/or a formation of the outer surface of its lowest wafer leaf that is liable to being damaged, on accountoftheconfigur- ation thereof and/or the consistency of its wafer leaf material, damage to this visible surface of the wafer block cannot be ruled out, which is caused by the fact that in the course of the rotational movement of the lifting conveyor screws the respective uppermost winding thereof rubs, in the manner of a circular milling cutter, on the surface of the lowest wafer leaf of the wafer block, which performs a translatory movement in the removal direction, and leaves a trace of damage there, which considerably impairs the appearance of the formed wafer block and substantially reduce the quality of the wafer end product.

Furthermore, the fact that the known device, on account of its conception, is dependent on the size of the wafer block to be formed, namely the width thereof, cannot be ignored. In fact, the spacing of the two conveyor screws of its lifting conveyor is dependent on the width of the wafer leaf to be handled or conveyed. In the event of the wafer block width being changed, the entire lifting device therefore always has to be reset by changing the axial distance between its two conveyor screws. This means an operating cost expenditure that is not inconsiderable and an even more serious loss in production time by resetting dead times caused thereby, not to mention the loss caused by interrupting the continuity of the production sequence.

Another disadvantageous factor in connection with this known device is to be seen in the fact that it is necessary to provide a stop, which follows the lifting movement, for the wafer leaves which have been lifted by the conveyor screws. The return of the stop must occur in two stages since at the same time as the completed wafer block formation is transported away from its position of joining, the cover leaf of the next wafer block is to be moved thereinto.

This causes an unavoidable expenditure that is not inconsiderable for the drive and control of the lifting movement of this stop. The disadvantageous consequence thereof is a certain unavoidable susceptibility to trouble and an increased service requirement occasioned thereby.

It is apparent that, in connection with the known devices of a related kind, the requirements of increasing the water block formation output and as gentle a treatment of the wafer leaves to be joined to form the desired wafer block during the handling thereof in the course of the entire wafer block formation process are not only interlinked in a specific way but even run counter to each other, namely in that, particularly for reasons of rational production at the lowest possible expenditure for installation and operating costs, and thus a lowering of the manufacturing price of the finished wafer end products and as a precondition therefor of the wafer blocks to be formed that is as far-reaching as possible, there are used for these wafer leaves which are as large-sized as possible and, on the other hand, for market reasons because of a desired large number of layers per wafer block with a predetermined total thickness thereof and/or a desired number of filling intermediate layers of large thick ness and/or heavy specific weight of the filling layer material, there are used wafer leaves which are particularly thin-walled and/or formed from particularly crisp or breakable material, which necessitate, for example on account of the specific development of their visible surface that lies on the outside and/or because of the consistency of their leaf material that is prone to damage, special risks of damage with the described disadvantageous conseqences to be taken into consideration.

According to one aspect of the invention there is provided a method for the product - -. of wafer blocks comprising at least one wafer leaf provided with a filling layer and one wafer cover leaf, in which method these wafer leaves with or without filling layers are successively joined by means of a respective forcibly conducted movement at a speed that is not dependent on their delivery speed to a predeter mined starting position for the joining to the desired wafer block in a direction that is substantially perpendicular to their delivery direction so as to form the desired wafer block which is then trans ported away from its joining position in order to clear this position for the next wafer block or the first wafer leaf thereof, in which the formed wafer block is transported away at a removal speed that is not dependent on the speed of the joining movement of the wafer leaves with or without filling layers nor the delivery speed thereof to their predetermined start ing position for the joining to the desired wafer block.

According to another aspect of the invention there is provided a device for the production of wafer blocks comprising at least one wafer leaf provided with a filling layer and one wafer cover leaf, which are succcessively joined by a lifting conveyor, which imparts to them a forcibly conducted movement in a direction that is substantially perpendicular to their delivery direction at a delivery speed impressed on them by a feeding conveyor so as to form the desired wafer block which is then transported away from its joining position by means of a withdrawal conveyor in order to clear this position for the following wafer block or the first wafer leaf thereof, comprising a withdrawal conveyor which can be driven at a speed that is independent of the joining speed of the lifting conveyor and also of the delivery speed of the feeding conveyor.

One device according to the invention, particuarly suitable for performing the method and described in more detail hereinafter, aims to bring into harmony to a very large extent, with simple and economic means, the conflicting requirements with respect to an increase in the number per unit of time of wafer blocks formed, even if wafer leaves which are large-sized and/or particularly thin-walled and/or are provided with particularly thick and/or particularly heavy filling layers are involved, and with respect to a very gentle treatment of such wafer leaves during the entire process of the wafer block formation in the interests of not only obtaining an optimum quality of the wafer end product, even if wafer leaves are used whose visible surface formation or consistency of the cover leaf material for the wafer block to be formed is extremely liable to damage, but also avoiding trouble in the continuous production sequ ence with the disadvantageous consequences there of and, while satisfying these simultaneous require ments, which was not considered possible until now, to provide a possibility of reliably increasing to a considerable extent the output of finished wafer blocks per unit of time, irrespective of the way in which the basic material therefor is formed, without any loss in quality and while avoiding an increased expenditure relating to operation and/or mainte nance, and allowing at the same time not only a continuous operation but also an automatically occurring operation which even includes automatic monitoring of its individual production and con veying cycles.

This device provides in a simple and low-cost manner a kinematic drive system for the operation of the feeding conveyor, the lifting conveyor and the withdrawal conveyor in which the drive for the withdrawal conveyor is designed, for the operation thereof, at a speed that is independent of the joining speed of the lifting conveyor and also of the delivery speed of the feeding conveyor.

The invention has thus realised for the first time that it is decisive to disengage the removal speed of the formed wafer block from the delivery speed of its individual wafer leaves, on the one hand, and from the speed at which these are joined to form the desired wafer block, on the other hand. In the known wafer block formation methods, the speed at which the wafer leaves are joined to form the desired wafer block is indeed independent of the speed at which these wafer leaves are delivered, but the removal speed for the completed wafer block is not independent.It is either forcibly combined with the delivery speed of the wafer leaves for the formation of the desired wafer block as for example in German Offenlegungschrift 2323646 in that the feeding conveyor for these wafer leaves is simultaneously the withdrawal conveyor for the formed wafer block, or is in direct constrained dependence on the speed of the joining operation, as for example in DE OS 2 809642 wherein the horizontal component of the lifting movement of the joining operation is used for the removal movement of the completed wafer block and the lifting conveyor thus simultaneously serves as the withdrawal conveyor.

Due to this disengagement of the removal speed of the completed wafer block both from the delivery speed of its wafer leaves and from the joining speed thereof, there is provided, according to the conception on which the invention is based, the possibility of influencing the speed cycle relating to time of each individual conveying operation in such a way that an optimum shortening of the total time required for the formation of the desired wafer block is possible, along with a respective adaptation of the speed patterns concerned to the respective mechanical requirements which result from the treatment of the wafer leaves to be joined to the desired wafer block in the individual treatment phases.Due to the conveying speed disengagement, each of the conveying operations involved can be effected so that it does indeed occur at the maximum speed possible but its speed pattern relating to time is so adapted that the accelerating and delaying forces arising therein always are within the scope specified by the formation of the wafer leaves which are with or without filling layers and are to be joined to form the desired wafer block. This means in detail that, on the one hand, the delivery speed of the feeding conveyor may be relatively high but may be braked or delayed, with a sufficiently flat pattern, towards the point in time when the starting position for the joining to the desired wafer block is reached. This reliably ensures, even if extremely unfavourable wafer leaf constructions are involved, that the entry of the wafer leaves into this starting position will be rapid, which was considered impossible until now, but will nevertheless be reliably without risk of damage to them.

On the other hand, the joining speed of the individual wafer leaves is basically independent of the feeding speed thereof. Of course, it may be chosen that it will be dependent on the feed speed if it is considered expedient according to the special development of the device provided for the performance of the method according to the invention.

However, there is indeed provided the possibility of adapting this joining speed in a suitable manner not only with respect to its absolute quantity but also with respect to its time pattern, that is to say with respect to its progress in time or over the path of the joining movement, and of even subjecting it to a desired program which may be independent of a possibly provided time program for the pattern of the delivery speed for the individual wafer leaves to their starting position for the joining to the desired wafer block.

Furthermore, the removal speed of the completed wafer block can also be freely chosen. It, too, may be subjected to a desired program for its progress in time, although in the interests of increasing the capacity of the wafer block formation it is only considered necessary to transport the completed wafer block away as fast as possible at as high a speed as possible, that is to say with as much acceleration as possible, the further speed pattern of the removal operation being of no importance to the wafer block formation capacity and thus being left to the onward conveyance devices.

Of special importance is however the possibility provided for the first time to be able to impart to the individual conveying operations not only different speed patterns in time, which are respectively adapted to the requirements of the treatment of the wafer leaves in the individual phases of conveyance, but also to be able for the first time to implement a displacement in time of the individual conveying movements relative to one another. This is of decisive importance for a shortening of the total time required for the formation of a desired wafer block.

According to the realisation on which the invention is based, the disengagement of the removal speed of the completed wafer block from the speed operations which are involved in the formation of this wafer block is of paramount importance. In fact, this makes the invention very largely independent of the constructional design of the device to be provided for the performance of the method according to the invention, although special constructional designs may well be capable of bringing specific procedural advantages and may therefore be preferable.

Of special importance is the fact that, in contrast to the known wafer block formation methods, there is no need to wait until the location for the first wafer leaf of the next wafer block is free but that time overlaps of the delivery and removal operations, and thus a time contraction of the entire production sequence, is possible.

The aim set is actually attainable merely by the disengagement, provided for according to the invention, of the removal speed of the completed wafer block from the delivery speed of the wafer leaves intended for its formation and from the speed of the joining thereof to the desired wafer block, but according to a subordinate inventive conception, which expediently develops the invention in a manner that is not obvious, a considerable improvement of the entire production sequence for the wafer block to be formed can be brought about, with respect to a shortening of the total production time thereof, if according to this subordinate inventive conception the wafer block formed is transported away by a form-locking application of force, for which purpose there is then provided devicewise a withdrawal conveyor which acts on the formed wafer block in a form-locking manner.

Due to these inventive measures, even extremely minimal inaccuracies of movement, which may still be possible, in the removal of the completed wafer block are reliably eliminated. In this connection, it should be remembered that in actual fact the invention is definitely capable of working with devices designed in the manner of the known devices as long as it is ensured that the conveying speed for the completed wafer block is disengaged from all other movement cycles occurring in the course of the wafer block formation so far as speed is concerned.For example, for attaining a minimum formation time for a desired wafer block of a predetermined leaf number, it would indeed not be optimal if this block were formed, for example, according to DE OS 2 809 642 but the removal movement of the completed wafer block were not left to the lifting conveyor but were brought about, by means of a withdrawal conveyor specially provided for this purpose and acting in a form-locking manner on the completed wafer block, but this would definitely allow, according to the invention, an increase in the capacity of the wafer block formation per unit of time that is not inconsiderable compared to this known method of providing a multi-layer wafer block.Due to the form-locking application of the removal force as opposed to the hitherto known pressure-locking application of friction of the force causing the removal movement, any imponderability is reliably eliminated which might result from inequalities in the friction contact or irregularities of the ratios of friction.The same applies also with respect to the DE OS 2323646. The conception, known therefrom, of forming a multilayer wafer block would also be possible by making use of the advantages of the invention if it were ensured that the removal movement of the completed wafer block will be effected at a speed that is independent of the delivery speed of the wafer leaves intended for its formation, which can be expediently effected by a withdrawal conveyor which is independent of the feed conveyor of this known device and which should expediently operate with a form-locking force application of the completed wafer block.

It has furthermore proved to be preferable if, according to another inventive further development, the formed wafer block is transported away by being supported by a force application tl,at is independent of both the delivery movement for he wafer leaves and the joining movement thereof and there is provided for this purpose devicewise a withdrawal conveyor which supports the formed wafer block by a force application that is independent of both the delivery movement for the wafer leaves and the joining movement thereof. Expediently, the force application may be applied by at least one pushing finger which engages beneath the formed wafer block. Accordingly, the withdrawal conveyor of the device according to the invention then comprises at least one pushing finger which engages beneath the formed wafer block.

In principle, the invention does not depend on the i question on which movement path the removal of the completed wafer blocks is effected. For example, a known device according to DE OS 2 323 646, wherein the formed wafer block is transported away on the same movement path on which the wafer leves are delivered for its formation, can be con verted by way of addition for the purposes of the invention provide that it is ensured that, in the manner according to the invention, the removal speed is independent of both the delivery speed of i the wafer leaves and the speed of joining the same.

In the construction of the feeding conveyor of this known device in a multi-belt design, a withdrawal conveyor could, for example, be so provided that it engages, with suitably designed pushing fingers, in the spaces between the individual belts of the feeding conveyor and slidingly pushes out the wafer block formed on the feeding conveyor through the feeding conveyor. However, an optimum utilisation of the possibilities opened up for a shortening of the block formation time by the invention is given if, according to another subordinate inventive concep tion, the formed wafer block is transported away on a movement path that is different from the delivery movement path for the wafer leaves and if the withdrawal conveyor comprises for this purpose a movement path that is different from the delivery movement path for the wafer leaves.

In a further expedient further development, the wafer block can be transported away on the plane of the delivery of its wafer leaves. It is however preferable if the formed wafer block is transported away on a plane that differs from the delivery plane of its wafer leaves. The removal may be effected in a plane that is lower or higher than the delivery plane of the wafer leaves. For this purpose, the strand of the withdrawal conveyor, which strand imparts to the formed wafer block the removal movement, may be expediently arranged beneath or above the plane of delivery of the wafer leaves thereof. The choice of one variant or the other depends on the method of joining the wafer leaves so as to form the desired wafer block.In most cases, it will be preferred to effect the removal on a plane that is higher than that for the delivery of the wafer leaves.

Irrespective of the association of the removal plane with the delivery plane of the wafer leaves, that is to say even if the completed wafer block is transported away in the same plane, the removal can be effected in the same direction as the delivery of the wafer leaves or in a direction transverse thereto. A with drawal conveyor for the removal of the formed wafer block on a plane that differs from the plane of delivery of the wafer leaves thereof also offers however the possibility of transporting the wafer block away in the opposite direction to the delivery direction. Such a design of the invention can be of advantage in cases where, due to particularly confined space conditions, a particularly short overall length has to be observed for the device according to the invention.

In a further constructional development of the invention, the withdrawal conveyor may be formed by an endless belt or chain track, on which there is arranged, projecting from it, at least one pushing finger for the formed wafer block. In fact, this construction allows in a particularly simple manner the realisation of a further subordinate inventive conception which is extremely useful for a particularly simple and expedient solution to the problems concerning the invention and according to which, in a construction of the invention with at least one withdrawal conveyor pushing finger, which engages beneath the formed wafer block, the pushing finger is returnable outside the conveying path of the withdrawal conveyor to its position of readiness for the removal of the next wafer block.By this means, it is expediently avoided that the return movement of the pushing finger of the withdrawal conveyor might impair the joining process of the next wafer block or the delivery of the first wafer leaf thereof to the starting position for the joining to the desired wafer block. On the contrary, it is ensured that, irrespective of the method chosen for the return of the pushing finger and of the time required therefor, the joining operation of the wafer leaves to the desired wafer block may occur so as to overlap in time and that undesirable dead times are avoided in this way. In principle, the withdrawal conveyor may be of any desired design, for example, in such a way that it carries out a reciprocating movement and comprises a pushing finger which can be extended from the delivery movement working path during the return movement.However, the design of the withdrawal conveyor as an endless belt or chain track with a pushing finger, which projects therefrom, arranged thereon or a pluralityof such.pushing fingersforthe formed wafer block is preferable inasmuch as a movement pattern of the pushing fingers that occurs in only one direction of movement is possible and any expenditure for reversal and braking and counter acceleration of relatively large masses thus becomes unnecessary.

If such a withdrawal conveyor designed as an endless belt or chain track only comprises one pushing finger, then an appropriate co-ordination of the movement pattern in time must be effected in such a way that the formed wafer block is transported away on the movement path of the withdrawal conveyor strand at the desired speed but that thereafter the pushing finger is so returned to its positions of readiness for the removal of the next wafer block that it is again available in time at the moment when this next wafer block has been completed. Evidently, a larger number of pushing fingers is desirable here for kinematic reasons.

Depending on the type and design of the guide of the wafer leaf movement during the joining of the wafer leaves to the desired wafer block, it may well be purposeful to provide only two pushing fingers on the belt or chain track. Although this has a favour able effect on the movement pattern inasmuch as the return movement of the pushing finger that has been brought into use need not be effected at such a high speed as for only one pushing finger, it must however be ensured that a guide stop for the wafer leaves to be joined to the desired wafer block is always available in time during the joining movement thereof in a working position, which stop has the function of a gate which opens at the moment when the respective wafer block is completed and allows it to be transported away.If, in a further inventive development, the succession of the pushing fingers of the belt or chain track is so used in this regard that there is formed by the respective wafer-block-remote rear of a pushing finger, which has just carried out its working path transporting away a formed wafer block, a compartment for the formation and reception of the next wafer block, then three or more pushing fingers must be arranged at regular intervals over the length of the endless belt or chain track. It is recommended, for reasons of a low constructional and materialwise expenditure and a minimal space requirements, to provide for three pushing fingers.In fact, such a construction is optimally suited for always having a pushing finger in the position of readiness for a push-out movement of a completed wafer block, while the preceding pushing finger, after having performed the removal movement for the preceding wafer block, serves as a stop, which forms a compartment, for the guidance of the wafer leaves moved by means of the lifting conveyor and to be joined to the desired wafer block, and for being able, simultaneously with the next removal operation of the withdrawal conveyor on only the required removal path, to take the third pushing finger in time to the position of readiness for the removal of the then following wafer block.

In order to eliminate to the largest extent any inaccuracies with respect to the positional association of the pushing fingers and thus also irregularities in the time sequence of the removal movement of the formed wafer block in the interests of an exact definition of the movment relationships, which is desired according to the invention, the belt or chain track may be kept in working tension through a fixed stop, according to a further expedient development of the invention.By this means, not only an exact definition of the positional associations of the individual positional associations of the individual pushing fingers and the movement patterns thereof is ensured with extremely simple means but any phenomena of vibration during the operation of a withdrawal conveyor developed in this way are also reliably avoided from the outset, such as might occur when a tensioning unit for the belt or chain track is used that works with spring force.

For the further promotion of the invention on the iines of shortening the time required for a complete block formation cycle even further, the formed wafer block may, in a further development of the invention, be transported away at a speed that changes according to a predetermined time pattern. For this purpose, there is provided devicewise a control unit for the drive of the withdrawal conveyor at a speed that changes over the removal path of the formed wafer block according to a predetermined time pattern.It is evident that this inventive conception is an advantageous contribution towards eliminating dead times of any kind to a very large extent, in that it can be ensured that the completed wafer blocks are accelerated as rapidly as possible to the maximum speed and are transferred at this speed to an onward transportation conveyor which runs at a corresponding speed and the space required for the formation of the next wafer block is thus cleared in the fastest possible way.

By utilising the conception according to the invention, the first wafer leaf of the next wafer block to be formed can be delivered at a virtually constant speed. To this end, provision may be made in the device according to the invention that the feeding conveyor for the delivery of the first wafer leaf of the next wafer block to be formed is operable at a virtually constant speed. However, in orderto increase the throughput rate, it may be expedient if the first wafer leaf of the next wafer block to be formed is delivered at a speed that changes according to a predetermined time pattern, for which purpose the feeding conveyor for the delivery of the first wafer leaf of the next wafer block to be formed is then operable at a speed that changes according to a predetermined time pattern.This subordinate inventive conception, which expediently develops the invention, also contributes in an advantageous man nerto a substantial shortening of the tota! block formation time and thus to a corresponding increase in the output, in that the delivery movement for the individual wafer leaves of the wafer block to be formed can be effected with such a time program, independently of any programwise pattern of the removal movement of the preceding wafer block, so that it does indeed occur at a maximum speed over the largest part of the delivery path but so that it is ensured that the conveying movement of the delivered wafer leaves occurs, shortly before they reach their starting position for the joining to the desired wafer block, at a speed that is not harmful for the wafer leaves strengthwise and the time required for the delivery of the wafer leaves to this starting position can thus be brought to a minimum, in adaptation to the strengthwise and kinematic conditions given by the respective design of the wafer leaves concerned. The choice of the time program to be used for the delivery movement of the wafer leaves is expediently made in accordance with these conditions specified by the wafer leaf to be conveyed and expediently also in co-ordination with the subsequent movement cycles. In a further development of the invention, the device according to the invention may be equipped with a control unit for the drive of the feeding conveyor at a speed that changes over the delivery path of the first wafer leaf of the next wafer block to be formed according to 3 predetermined time sequence.

Furthermore, the first wafer leaf c. tic next wafer block to be formed may be delivered si.- utltaneously with the removal of the preceding wafer block. In the interests of an even more far-reaching increase in the throughput rate, provision may however be made for the first wafer leaf of the next wafer block to be formed to be delivered earlier than the start of the removal of the preceding formed wafer block.A construction according to this subordinate inventive conception, whose realisation is rendered possible for the first time by the superordinate measures according to the invention, signifies an overlap in time of the wafer leaf delivery and the wafer block removal in different wafer blocks, in other words a displacement in time of the block formation phases of two consecutive wafer blocks. The time gain that is possible by this means for the first time is obvious.

For the rest, this possibility of a time gain is not confined to the first wafer leaf of the wafer block that follows a wafer block which is completed and can be transported away; on the contrary, in a further expedient development of the invention, the wafer leaves following this first wafer leaf of a wafer block can be delivered in the same way as this leaf. For this purpose, there may be provided in the device according to the invention a control unit for the drive of the feeding conveyor at a speed that changes over the delivery path of all wafer leaves of a wafer block to be formed according to a predetermined time pattern.

For the rest, the invention offers the possibility of joining the wafer leaves in known 'per se' manner at a constant joining speed or at a joining speed that is reduced in known 'per se' manner towards the joining moment so as to form the desired wafer block. A correspondingly designed lifting conveyor is respectively provided for this purpose. For exam ple, it would definitely be possible to provide within the scope of the invention a lifting conveyor which is designed according to DE OS 2809642 and by means of which the wafer leaves are joined to form the desired wafer block at a constant joining speed.

On the other hand, if a joining speed pattern that is not constant is desired, it would also be possible to use within the scope of the invention a lifting conveyor according to DE OS 323 646 which works by means of lifting star wheels which are equipped with lifting fingers which engage beneath the wafer leaves.This is always preferable if, according to another further development of the invention, the joining movement is to be imparted to the wafer leaves only after they have reached a predetermined associated position fortheirjoining to the desired wafer block, in other words there is provided a predetermined associated position, only after the attainment of which the lifting conveyor can be brought into operative connection with the wafer leaves which are to be joined to the desired wafer block so as to impart to them their respective movement of joining.On the other hand, it may be expedient in the interests of reducing the working time also in the course of the lifting movment of the wafer leaves if, in an alternative development of the invention, the movement of joining is imparted to the wafer leaves already before they reach a prede termined associated position for their joining to the desired wafer block, and accordingly, the lifting conveyor can be brought into operative connection with the wafer leaves to be joined to the desired wafer block before they reach a predetermined associated position for their joining to the desired wafer block so as to impart on them their respective movement of joining.For, within the scope of the invention, is indeed possible to impart to the wafer leaves to be joined to the desired wafer block a lifting movement component prior to the completion of their delivery movement by means of, for example, the lifting finger construction according to DE OS 2 323 646 and thus to utilise a proportion of the actual delivery time for the joining movement.

For the rest, it is possible, within the scope of the invention, to form the wafer block by superimposing its wafer leaves on one another from the top or else by adjoining its wafer leaves from the bottom. The lifting conveyor used will be designed accordingly.

For the case of the formed wafer block being transported away on a plane that is different from the delivery plane of its wafer leaves, a preferred construction of the invention has been particularly well proven wherein the wafer leaves to be joined to the desired wafer block are each delivered against a stationary stop, which defines a starting position for the joining process, and are during the course of the joining movement moved along it, whilst remaining in abutting contact therewith.Accordingly, the device which works so as to transport the formed wafer block away on a plane that is different from the plane of delivery of its wafer leaves, is so designed that there is provided a stationary stop which defines a starting position for the joining of the wafer leaves to the desired wafer block and against which the wafer leaves are moved and, while remaining in contact therewith, are moved along it during the course of the joining movement. By this means, the disadvantages of known devices with respect to the expendi ture forthe drive and control mechanism of the guide stop for these wafer leaves, which has to be removed from the conveying path or follows the movement of the wafer leaves to be joined to the desired wafer block, are avoided with simple and low-cost means.This is made possible for the first time by the disengagement according to the invention of the removal speed from both the delivery speed of the wafer leaves and the joining speed thereof so as to form the desired wafer block.

For the rest, an expedient development of this inventive conception has been particularly well proven, wherein the stationary stop has an extension which is approximately aligned therewith and can be removed from the removal path of the withdrawal conveyor. This extension can be expediently removed from the removal path of the withdrawal conveyor by a swivel movement. In the preferred constructional form of the invention comprising a withdrawal conveyor which is formed by an endless belt or chain track and on which at least one pushing finger, which projects from the conveyor, is arranged, the stop extension may be provided on this belt or chain track of the withdrawal conveyor, in an expedient further development.

In an inventive further development, the stop extension may be formed by the rear of a pushing finger that is remote from the wafer block. If several pushing fingers are provided over the length of the belt or chain track, provision may furthermore be made for the rear that is remote from the wafer block of the pushing finger which removes the preceding formed wafer block to be operative as the stop extension for the formation of the next wafer block.

By this means, the compartment formation for the joining of the individual wafer leaves to the desired wafer block, which has been described above, is considerably promoted in the zone of the withdrawal conveyor with the described advantages concerning the movement pattern and the time savings attainable thereby.

Furthermore, the invention offers the possibility of adapting to a very large extent even to the most unfavourable strength relationships by means of a linear support of the wafer leaves during the joining thereof to the desired wafer block, in such a way that, even if the kinematic possibilities of a highvelocity conveyance of the wafer leaves are very largely utilised involving relatively severe braking operations, it is possible to ensure, even if very unfavourable strength relationships prevail on account of the size and/or the thickness and/or the consistency of the wafer leaf material and/or the filling layer material and/or the weight thereof in respect of the wafer leaf concerned, an extremely gentle treatment thereof and virtually to eliminate any risk of damage.

Another subordinate invention conception aims in the same direction. It, too, is meant to contribute to treating the wafer leaves to be handled, irrespective of their type, design and/or size, while they are joined to form the desired wafer block in such a way that the movement velocities can be increased to the desired extent and, if applicable, with the desired programmed time pattern without the risk of impairing or even damaging these wafer leaves. According to this inventive conception, the wafer leaves are respectively joined to form the desired wafer block with a support that is free from sliding movement.

Accordingly, a device according to the invention may comprise a support that is free from sliding movement for the wafer leaves to be joined to the desired wafer block during the joining process. In a further expedient development of this inventive conception, there may be provided for supporting the wafer leaves to be joined to the desired wafer block supporting fingers which engage beneath these from their side and are approximately parallel to their plane. Advantageously, these fingers may furthermore be each provided with a carrier sleeve which is mounted thereon for a rotational movement relative thereto.It is evident that, due to the measures of this inventive conception and its developments and irrespective of the question whether the wafer leaves, prior to the initiation of the lifting or lowering movement, which joins them to the desired wafer block, to a starting position, are braked for this latter or whether such a joining movement is imparted to them already in the course of their delivery movement and furthermore irrespective of whether the joining to the desired wafer block takes place on the level of the feeding conveyor or in a plane that is higher or lower than this conveyor and, finally also irrespective of whether the removal of the completed wafer block takes place on the level of the feeding conveyor or in a plane that is higher or lower than this conveyor, it is always ensured not only that these wafer leaves can be kept free from impairments of their visible surface or even damage thereto by movements of the lifting elements of the lifting conveyor relative to them but also that an exactly defined position of the wafer leaves on the respective conveyor can be maintained, whereby any inaccuracies of association are reliably avoided and there is therefore made possible an exact association in time of the successive wafer leaves as a precondition for a maximum shortening of the working time for each block formation cycle due to the elimination of the necessity to keep available specific dead times of predetermined minimum length.

According to a subordinate inventive conception, which furthermore advantageously improves the invention, the variant of the invention providing for the wafer leaves to be placed one above the other from the top can be particularly expediently utilised in that there is provided as the lifting conveyor a known 'per se' conveyor with lifting fingers which each carry out a rotational movement around an axis of rotation that is parallel to the delivery direction of the wafer leaves.Due to the fact that the wafer leaves are joined to the desired wafer block in known 'per se' manner by means of lifting fingers which each carry out a rotational movement around an axis of rotation that is parallel to the delivery direction of the wafer leaves, there is provided for the first time the advantageous possibility of deiivering a following wafer leaf with or without a filling layer already during the joining process of the preceding wafer leaf and of thus realising a displacement in time of the delivery movement and the joining movement, which results in a considerable time gain.In an expedient continuation of this inventive conception, provision may be made that the delivery of a wafer leaf will only be commenced when the lifting fingers have respectively passed through an angle of rotation for which the ratio of the actual lifting height to the maximum lifting height corresponds to the ratio of the sum of the wafer leaf thickness and half the lifting finger diameter to the distance of the axis of the respective lifting finger from the axis of rotation of its rotational movement.Furthermore, the delivery of a wafer leaf should expediently be completed before the lifting fingers have respectively passed through an angle of rotation for which the ratio of the difference between the actual lowering height of the respective lifting finger and the max imum lifting height thereof to this maximum lifting height corresponds to the ratio of the sum of the wafer leaf thickness and half the lifting finger diameter to the distance of the axis of the respective lifting finger from the axis of rotation of its rotational movement. For it has been found that these are the limiting conditions for allowing the lifting fingers procedurewise still just about to pa --- a wafer leaf that has been delivered during their rational movement to the starting position for Tv .a joining operation to the desired wafer block without being obstructed in their movement path by this leaf.

Devicewise, there may be furthermore provided for this purpose that the lifting fingers are each arranged at a distance of their axes from the axis of rotation of their rotational movement that corres ponds at least to the square root of the product of the square root of two and the sum of the thickness of the delivered wafer leaves and half the lifting finger diameter. Furthermore, the lifting fingers should expediently each have a lifting finger diameter that corresponds at the most to the ratio of the product of the square root of two and the square of the distance of the axis of the respective lifting finger from the axis of rotation of its rotational movement to the thickness of the delivered wafer leaves.And, finally, it has proved to be preferable if the axes of rotation for the rotational movement of two lifting fingers which are arranged in succession in the direction of delivery of the wafer leaves are arranged at an interval that corresponds at least to the difference between the length of the delivered wafer leaves and the ratio of the sum of the thickness of these and half the lifting finger diameter to the distance of the axes of the lifting fingers from the associated axis of rotation for the rotational movement of the respective lifting finger.It is evident that for the possibility of using at least partly the time required for the joining movement for the delivery of the next wafer leaf with or without a filling layer to the starting position thereof for the joining operation, it is of considerable importance, according to the aforedescribed inventive measures, that the distance between the axes of rotation of both lifting star wheels, which carry lifting fingers and are arranged one behind the other in the delivery direction of the delivery conveyor, must be co-ordinated with the respective wafer leaf length in the delivery direction in such a way that the lifting fingers can be raised to a sufficient height prior to the arrival of the delivered wafer leaf and can be taken past the wafer leaf after the arrival thereof without being obstructed by the same in the course of their lowering movement.

For this purpose, provision may be made, in an expedient continuation of this inventive conception, that for a given rotational speed of the lifting fingers the wafer leaves are each delivered at a speed that corresponds to at least the ratio of the wafer leaf length in the delivery direction to the difference between the angle of a quadrant and the angle for which the ratio of the projection of half the unit circle diameter, which forms its one side, on the perpendicular line on its other side to half the unit circle diameter corresponds to the ratio of the sum of the .wafer leaf thickness and half the lifting finger diameter to the distance of the axis of the respective lifting finger from the axis of rotation of its rotational movement.It is furthermore provided that for a given delivery speed of the wafer leaves, the lifting fingers are moved at a rotational speed that at the most corresponds to the product of the ratio of this delivery speed to the length of the wafer leaves and the difference between the angle of a quadrant and the angle for which the ratio of the projection of half the unit circle diameter, which forms its one side, on the perpendicular line of its other side to half the unit circle diameter corresponds to the ratio of the sum of the wafer leaf thickness and half the lifting finger diameter to the distance of the axis of the respective lifting finger from the axis of rotation of its rotational movement.

The constructional form of the invention compris ing a conveyor with lifting fingers, which each carry out a rotational movement around an axis of rotation that is parallel to the delivery direction of the wafer leaves, as the lifting conveyor offers, for the rest, the advantageous possibility of influencing the time pattern of the lifting and lowering movements for the first time in the scope of the invention if respectively four or a larger even number of lifting fingers are provided for each axis of rotation or each lifting star wheel. In contrast to known constructions of such devices, it is in fact thus possible to bring about a kind of intermediate stage between the wafer block joining by superimposition from the top and by joining layers from the bottom.Whereas in the known constructions, for example that according to DE OS 2 323 646, the joining is effected by lowering the previously raised wafer cover leaf or the previously formed and raised partial wafer block on the next filling-coated wafer leaf which has meanwhile been delivered to the position of readiness, namely on account of the speed change, following a sine curve, with the time or the lifting path at a speed that is highest at the moment when the wafer cover leaf or the formed partial wafer block is superimposed, the wafer cover leaf resting on the elevated lifting fingers or the correspondingly held partial wafer block is in this preferred construction of the invention indeed lowered in the same way, but the filling-coated wafer leaf which has in the meantime been delivered to the position of readiness by the lifting fingers which follow in the direction of rotation and are being raised at the same time and were previously in the horizontal position is raised so that it comes to meet the lowered wafer cover leaf or partial wafer block in its movement. The desired favourable consequence is a comparatively gentler encounter of the two parts of the wafer block to be formed than that of known wafer block formations.

This not only basically reduces to a considerable extent the risk of damage to one or both parts of the wafer block and the possibility of the filling layer compound being squeezed out laterally but the theoretically still existing possibility of this happening is also removed from the sphere of the conveyors so that any contamination of them is effectively avoided.

In order to improve the invention further in regard to an automatic operating sequence of the method, it is possible, in an inventive development, to monitor the wafer leaves to be joined to the desired wafer block to the effect whether they have reached a predetermined position in the course of their delivery movement, preferably a starting position for their joining to the desired wafer block, whereupon the movement of joining is then initiated in dependence on the attainment of this predetermined position.Devicewise, there is then provided for this purpose a monitoring unit, by means of which the wafer leaves to be joined to the desired wafer block can be monitored to the effect whether they have reached a predetermined position in the course of their delivery movement, preferably a starting movement for their joining to the desired wafer block, and by means of which the lifting conveyor is then actuatable in dependence on the attainment of this predetermined position. In this way, an automatic control of the movement cycle of the lifting conveyor is brought about so that this latter will always come into action when a wafer leaf which is required for the wafer block formation and which has been provided with or is without a filling layer is available.

According to another inventive development, an automatic control for the removal of each completed wafer block may be provided in a similar manner.

For this purpose, the wafer leaves to be joined to the desired wafer block may be monitored to the effect whether a predetermined one of them has reached a predetermined position in the course of its delivery movement, preferably a starting position for its joining to the desired wafer block, whereupon the removal movement for the formed wafer block is then initiated in dependence on the attainment of this predetermined position.Devicewise, there is provided for this purpose, according to this subordinate inventive conception, a monitoring unit, by means of which the wafer leaves to be joined to the desired wafer block can be monitored to the effect whether a predetermined one of them has reached a predetermined position in the course of its delivery movement, preferably a starting position for the joining to the desired wafer block, and by means of which the withdrawal conveyor for the removal of the formed wafer block is then actuatable in dependence on the attainment of this predetermined position.

Both last-described inventive conceptions, which are directed at automatising and thus increasing the reliability of the procedural cycle according to the invention with a reliable observation of the shortening ofthe production time aimed at, can advantageously also be jointly realised. An expedient further development is characterised in that the monitoring unit comprises a scanning probe which is arranged in the conveying path of the feeding conveyor and which preferably works in a contactfree manner. This scanning probe may be so designed that it only responds to the presence of a wafer leaf as such at a predetermined point of the conveying path of the feeding conveyor and then serves as a detecting element for the initiation of the conveying movement of the lifting conveyor.

However, this scanning probe may be so designed that it can detect, for example through a counting mechanism arranged downstream thereof, the presence of a specific number of wafer leaves and thus of a specific first or last wafer leaf from this wafer leaf sequence, which is then expediently a wafer leaf without a filling layer which is to be used as a wafer block cover leaf, or is even directly capable of ascertaining whetherthe arriving wafer leaves are provided with filling layers or are without filling layers. In such a case, this scanning probe can then expediently function as a detecting elementforthe initiation of the removal movement of the withdrawal conveyor for the formed wafer block.It has furthermore proved to be particularly expedient if the scanning probe is arranged so as to be displaceable along the conveying path of the feeding conveyor. For this allows adaptations to changed operating conditions or only re-adjustments to be effected in a simple manner.

Finally, according to another subordinate inventive conception, which improves the automation in the afore-described manner, provision may be made for the removal movement of the formed wafer block to be terminated by this wafer block itself or in dependence on the movement of a monitoring element which corresponds to its movement. For this purpose, there may be provided devicewise, according to the same inventive conception, an automatic switching-off means for the withdrawal conveyor which is actuatable by the wafer block itself transported away by this conveyor or in dependence on the movement of a monitoring element that corresponds to its movement.Expediently, the automatic switching-off means may comprise at least one switching means which is arranged in the conveying path andlor in the return path of the withdrawal conveyor and which is actuatable by a switching element moved by the withdrawal conveyor and which produces a switching-off pulse for the withdrawal conveyor.It has proved to be particularly preferably if, in an expedient development of this inventive conception, the automatic switching-off means comprises a switching-over means which is arranged upstream in the conveying path of the switching-off means, which produces the switch-off impulse for the withdrawal conveyor, and which is actuatable by the same switching element that is moved by the withdrawal conveyor and produces a switching-over pulse for reducing the removal speed to a lower conveying speed of the withdrawal conveyor. Bythis means, it is ensured that, prior to the switching-off of the withdrawal conveyor, which is always effected if this conveyor is to be moved to the waiting position for the next wafer block removal operation, until the next wafer block is completed, the movement speed of the withdrawal conveyor is reduced to such an extent that, at the moment when the movement of the respective conveying phase has finally been stopped, there are no longer to be applied any notable delaying forces and by this means a contribution is made to allow the conveying members of this withdrawal conveyor which come into operative connection with the next wafer block to be transported away, for example the pushing fingers thereof, to be kept in exactly defined waiting positions..

This, in turn, results advantageously in an exact timing of the removal movement and any movement cycles of the upstream conveyors which are displaced in time relative to this movement, with a corresponding shortening of the time required for the sequence of a complete wafer block formation cycle.

Furthermore, it has proved to be expedient if the switching means and/or the switchSng-over means work in a contact-free manner, for ex;:7ple optically or opto-electrically or opto-electronically, the switching element being formed by the wafer block that is transported away or by a switching lug which is arranged on the withdrawal conveyor, preferably on the pushing finger or each of the pushing fingers thereof.

However, another further development of this inventive conception has in many cases proved to be more expedient for constructional and operational reasons, wherein the automatic switching-off means comprises a switching means which is independent of the conveying path and/or the return path of the withdrawal conveyor but is dependent on the move ment cycle of a stationary component of the withdrawal conveyor, such as the angle of rotation of the axis or shaft of a deflection sheave thereof.In the case of a construction of the invention with a withdrawal conveyor that is formed by an endless belt or chain drive comprising at least one pushing finger for the formed wafer block, the switching means may expediently comprise a switching disc, which is arranged on an extension of a shaft or axle of a deflection sheave of the withdrawal conveyor and which comprises at least one recess, which is arranged in a predetermined angular association, and a stationary scanning probe, by means of which there can be produced a switching-over and/or a switching-off pulse for the removal speed.The switching disc may well have several recesses, for example two which are angularly staggered, which may then be used as pulse generators for a stepped reduction of the movement speed of the withdrawal conveyor, the recess which is the last in the direction of rotation of the switching disc then initiating the final switching-off of the conveying movement or speed of the withdrawal conveyor.

Finally, according to a last inventive conception, which advantageously develops the invention and is subordinated in an expedient manner to the solution to the problems underlying the invention, there may be provided an anti-congestion means, by means of which a warning signal can be given and/orthe functions of all conveyors can be switched off in the event of a build-up of wafer leaves. By this means, a contribution is made towards reliably avoiding any trouble, caused by jamming or contamination, in the movement cycles of all the conveyors, which might disturb or even stop the operation of the device according to the invention.In an expedient development of this inventive conception, the anticongestion means may comprise a scanning probe, which is arranged in the conveying path of the feeding conveyor and preferably works in a contactfree manner, and another scanning probe, whose distance from the former can be set along the conveying path of the feeding conveyor in accordance with the length of the wafer leaves to be conveyed in the conveying direction of the feeding conveyor, and, with a simultaneous actuation of both scanning probes, can produce a trigger pulse for the signal emission and/or for the switching-off of the functions of all the conveyors.

For the rest, the same scanning probe may well be used as the scanning probe of the monitoring unit influencing the lifting conveyor and the monitoring unit acting on the withdrawal conveyor as well as one of the two scanning probes of the anticongestion means, in that this probe is then provided with multiple functions.

Hereinafter, the invention will be described in more detail, purely by way of example, with reference to an exemplified embodiment which is only diagrammatically shown in the drawings, in which: Figure 1 shows a longitudinal section through a device according to the invention along the line I-I of Figure 2, wherein there is shown, in the form of an electric circuit diagram, a possibility of construction for a monitoring means and an anti-congestion means combined therewith as well as diagrammatically two alternative variants for, on the one hand, an automatic switching-off means which is actuatable in dependence on the movement of a monitoring element that corresponds to the removal movement of a completed wafer block and, on the other hand, an automatic switching-off means which is not dependent on the conveying path and/or the return path of the withdrawal conveyor but is dependent on the movement cycle of a stationary component of the withdrawal conveyor, Figure 2 shows on a somewhat reduced scale a top view of the device shown in Figure 1, without the withdrawal conveyor, and Figure 3 shows a view of the device like Figure 1 in the direction of the arrow E (Figure 1 ) with partial sections in the zone of the lifting conveyor and the withdrawal conveyor respectively.

The device according to the invention comprises a feeding conveyor 1 which is formed by individual belts with outward tracks 1 a, which only extend as far as a short distance from the inlet of the lifting conveyor, which is designated 2 as a whole, and inward tracks 1 b, which run in the longitudinal direction through the lifting conveyor 2 and extend beyond this latter, and is intended for wafer leaves which come in the usual way from a wafer leaf store or directly from an automatic wafer baking machine and which are delivered on the feeding conveyor 1 in the delivery direction A in a numerical sequence that corresponds to the wafer layer number desired for a specific wafer block design, either the last or preferably the first wafer leaf of this wafer leaf sequence not having any filling layer, while the other wafer leaves of this wafer leaf sequence are each provided with a filling layer which has been previously applied in a suitable known manner. Carried by the belts of the inner tracks 1 b of the feeding conveyor 1, the delivered wafer leaves successively reach the stationary stop 20, which projects into the conveying path and which may be formed by a number of strips which stand up in a rake-like manner, as shown by way of example in Figure 3. This stop 20 defines with its contact side a starting position 22 for the joining of the wafer leaves to the desired wafer block.

For bringing about this joining, there is provided a lifting conveyor which is designated 2 as a whole and which is formed by four lifting star wheels 2b, two of which are respectively symmetrically arranged on a shaft laterally of the central longitudinal axis of the conveyor, the lifting star wheel pairs being arranged behind one another in the direction of conveyance A of the feeding conveyor 1 at a distance and each lifting star wheel having, in an identical arrangement and association, four lifting fingers 9 which are arranged crosswise, that is to say at identical angular distances from one another, and which extend parallel to the plane of the feeding conveyor 1 and thus to the plane of the wafer leaf respectively conveyed thereon.The position of association of the lifting fingers 9 of the lifting conveyor 2, which is driven through a stepping motor - as can be seen by way of example in Figure 3 -, is such that respectively two lifting fingers 9 of each lifting star wheel 2b of the lifting conveyor 2 engage, in a position that is approximately parallel to the wafer leaf plane, underneath respectively one wafer leaf which has been conveyed to the starting position 22 for the joining operation of the wafer leaves, while, with a connection plane that is vertical to the connection plane of these two lifting fingers, the two other lifting fingers 9 are respectively so positioned that one thereof is situated beneath the wafer leaf and the other above the wafer leaf.

Above the starting position 22, which is defined by the stop 20 stationarily arranged in the conveying path of the feeding conveyor 1,for the joining of the individual wafer leaves to the desired wafer block, there is arranged a withdrawal conveyor for the completed wafer block which is designated 3 as a whole.This conveyor is formed by belt or chain tracks 4 which are mounted with the pivots 3a of their deflection sheaves in the same way as the withdrawal conveyor 1, with the undesignated pivots of its deflection sheaves, and the lifting conveyor 2, with the pivots 2a of its lifting star wheels, in the machine frame, which is designated 50 as a whole, and - as is apparent for example from Figure 3 - are arranged in pairs so as to be symmetrical about the central longitudinal axis of the system and on which there is fastened a number of pushing fingers 5, in the exemplified embodiment shown five pushing fingers 5, with claws 5a arranged thereon.As illustrated for example in Figure 3, the withdrawal conveyor 3 is driven by a stepping motor 33 through a chain drive 33a and a pinion 33b seated on the shaft 3a in a manner similar to the lifting conveyor 2 through the lifting star wheel motor 32, which is designated as a stepping motor, through a chain drive 32a and a chain pinion 32b seated on one of the lifting star wheel shafts 2a.

For the rest, there exists between the two lifting star wheel shafts 2a of the lifting conveyor 2 a kinematic transfer connection 2c of suitable design, which is diagrammatically shown in Figure 2 and may be, for example, in the form of a chain or belt drive.

The withdrawal conveyor 3 is so arranged that there is defined by two of its deflection shafts 3a a removal strand which extends substantially parallel to the conveying track 21 of the feeding conveyor 1.

The two deflection shafts 3a of the discharging conveyor, which define this removal strand of the discharging conveyor 3, are connected by a bridge 10, on which another deflection pulley, which serves as a tensioning station for the belt or chain drive 4 of the withdrawal conveyor 3, is supported through a screw connection 11, 12, 12a including a screwed shank 11 which in a thread connection 12 in the bridge 10 is adjustable transversely to this latter and can be fixed in every desired position by means of a mating means 12a.

The association in height of the withdrawal conveyor 3 with the feeding conveyor 1 and respectively with the starting position 22 defined thereon for the joining of the individual wafer leaves to the desired wafer block is such that the conveying path 23 of the removal strand of the discharging conveyor 3 is in a plane which is higher than the plane a of the conveying path 21 of the feeding conveyor, which simultaneously defines the level of the starting position 22 of the wafer leaves for their joining to the desired wafer block. The withdrawal conveyor 3 is so driven that its removal strand moves in the direction D that corresponds to the delivery direction A of the feeding conveyor 1.

The arrangement of the three pushing fingers 5 which are arranged on the two parallel tracks of the belt or chain drive 4, which form the withdrawal conveyor 3, and which are each provided in a rake-like multiple arrangement, as can be seen for example in Figure 3, is such that the wafer-blockremote rear of a pushing finger 5, which has just pushed out a completed wafer block and has come to a standstill, always presents itself as an extension of the stop 20 or its guiding surface 22, which extension is aligned with the corresponding surface of the stationarily arranged stop 20 in the conveying path 21 of the feeding conveyor 1 for the wafer leaves, for the movement of joining the individual wafer leaves to the desired wafer block in the course of the actuation of the lifting conveyor 2 when the lifting finger 5 that is next in the sequence of operative engagement is, with its claw 5a that connects its individual members in a rake-like manner, just in the position of readiness for the next push-out of the following wafer block after the joining operation thereof has been completed. The lifting finger 5 which, after having completed its removal movement, serves as an extension of the guide stop 20 for the lifting movement of the wafer leaves in the lifting conveyor 2 is shown on the left-hand side in Figure 1 above the stop 20, while the lifting finger 5 which stays in the position of readiness for the removal of the next wafer block following the completion thereof is shown on the right-hand side in Figure 1 above the lifting conveyor 2 lifting star wheel 2b on the inlet side.

The process of forming a wafer block according ta the device is asfollows:-Asuccession of wafer leaves, the first one of which is without a filling layer while the following wafer leaves are provided with filling layers, runs on the feeding conveyor 1, in the direction of conveyance A thereof, with the lifting fingers 9 of the lifting conveyor 2 in the position shown in Figure 1, until the front edge of the foremost wafer leaf rests against the contact surface 22 of the stationary stop 20. Expediently, the delivery speed of the feeding conveyor 1 can be so influenced through a program control unit 34 waiting on the drive 31 thereof that, despite a high value provided over the essential range of the delivery path of the feeding conveyor 1, it is so braked in time that the first wafer leaf comes gently into contact with the stationary stop 20, thus reliably avoiding damage thereto in spite of the high delivery speed thereof and even if extremely unfavourable kinematic and strength conditions thereof prevail.

Within the sphere of the delivery path 21 of the feeding conveyor 1 there is arranged a scanning probe 14 of a monitoring unit 30 which detects in a contact-free manner, for example optically or opto electrically or opto-electronically, whether the wafer leaf which is conveyed past it on the feeding conveyor 1 has passed it properly. If this is the case, the monitoring unit 30 will give, in a manner yet to be described, a starting pulse for the stepping drive 32 of the lifting conveyor, by means of which the two lifting star wheels 2b of the lifting conveyor 2 rotate in opposite senses in the direction of the arrows B and C.This causes the lifting fingers 9, which are facing one another and are situated beneath the wafer leaf delivered to the starting position 22, to come into operative engagement with the wafer leaf underside and to lift this leaf from the plane a to the plane b. Here, this wafer leaf stays until the next wafer leaf, which is provided with a filling layer, is delivered on the feeding conveyor 1 to the starting position 22. This condition is monitored in the same way by means of the scanning probe 14 and a corresponding next starting pulse is given forthe lifting conveyor 2.By the starting thereof, the adjacent lifting fingers 9 situated beneath this wafer leaf now come into operative engagement with the bottom surface thereof and raise this leaf in a comparable manner to the two preceding finger pairs of the lifting conveyor 2, which lifted the preceding wafer leaf without a filling layer and therefore intended as the wafer cover leaf of the wafer block to be formed. Movementwise, the latter comes forward to meet the filling-coated wafer leaf because the lifting fingers 9 carrying it are lowered again. The two wafer leaves meet, after having reached an angle of rotation of approximately 45 , and are joined in this position, guided by the guiding stop 20 with its extension 5 or the guide surface 22 formed thereby, so as to form a partial wafer block.

This joining process thus occurs in a position that is remote from the starting position 22, namely on a level that is higher than the level a thereof. By this means, the location for the starting position 22 of the wafer leaves is kept free from contamination and the like. However, the formed partial wafer block is not continued to be lowered since the lowerfillingcoated wafer leaf is moved farther to the top by the lifting movement of the lifting fingers 9, which support it, in the direction of the arrows B and C and the wafer cover leaf meanwhile freely rests thereon, after the lifting fingers 9 which supported this leaf until then have come clear thereof by a respective continued rotation.In spite of some known components being used, the arrangement substantially differs, already to this extent, from the known device according to DE OS 2323 646 wherein the formation of the partial wafer block is effected on the level of the plane a of the feeding conveyor, for which purpose the previously raised wafer leaf has to be lowered from its lifted position to its joining position on the level of the plane a. The time gain achieved by the arrangement in this partial phase of the wafer block formation is evident.

The filling-coated wafer leaves which follow on the feeding conveyor 1 and which may be intended for the formation of the same wafer block are delivered in the same way and are joined by means of the lifting conveyor 2 to the partial wafer block that has been previously formed and is provided with more and more layers.When the intended layer number has been reached, there is produced, through the scanning probe 14 and a counting mechanism of the control unit 30, which mechanism is arranged downstream of the latter and can be set to the desired layer number program for the desired wafer block, a starting pulse for the drive 33 of the discharging conveyor 3, which drive is designed as a stepping motor, whereupon the discharge drive 3 is now started and its pushing finger 5, which is in the position of readiness, is brought, with the claw 5a which engages under the formed wafer block, preferably in the highest lift position, on the plane b, into operative engagement with this completed wafer block and removes it on its removal path 23 on the level of the plane bin the direction of the arrow D and transfers it to an onward transportation conveyor 7 arranged downstream thereof.Expediently, the removal process, for its part, may be also controlled by a time program, namely expediently in such a way that the wafer block to be transported away is brought to the maximum removal speed with as steep a time speed pattern as possible, i.e.

with as much acceleration as possible, and is transferred at this speed to the onward transportation conveyor 7, in ordertocleartheswing-in range for the next lifting finger pair which carries the wafer cover leaf of the next wafer block that is to be formed.

In order to allow the desired speed patterns in time to be operated at the corresponding high accelerations, the device here too, makes a systematic contribution, in the interests of an extremely rational production with an extremely far-reaching utilisation of the existing wafer block material and of as damage-free a handling thereof as possible for the purpose of avoiding any edge zone waste, towards initiating without risk the high forces which are required for the desired high accelerations, particularly for the completed wafer block mass to be accelerated, which mass is not inconsiderable, in that there is provided not only one or several pushing finger(s) 5, which are arranged in a rake-like fashion and engage behind the formed wafer block, as might well be provided within the scope of the invention - but also a specially designed and dimensioned pushing claw 5a which is carried by several pushing fingers 5, which are arranged so as to be parallel to one another, and is so designed that it not only engages under the completed wafer block to be removed in a carrying manner from the bottom but is also in form-locking force initiation contact with the rear edge thereof over the entire length, and this not only over the length of the lowest wafer leaf layer of the wafer block but expediently y over several wafer leaf layers so that the pushing force for the removal does not have to be transmitted via the filling layer compound to the higher wafer leaf layers and there are thus effectively and reliably avoided shearing movements in the individual filling coatings, on the one hand, and displacing movements of the individual wafer leaf layers relative to each other, on the other hand, in the course of the removal movement of the wafer block.

On the same line, to the effect that measures must be taken, particularly wherever for reasons of the procedural sequence forces acting so as to destroy the wafer leaves to be handled or wafer block edge zones have to be expected, to ensure a particularly gentle initiation of such forces orthe handling of the wafer leaves or wafer block that is without risk of damage, is the possibility, which is indicated in the right-hand inlet-end lifting star wheel 2b of the lifting conveyor 2 in Figure 1 but not in the left-hand lifting star wheel or which is shown by way of example in Figure 3, of providing a slide-movement-free relative movement of the lifting fingers 9 and the wafer leaf to be lifted during the lifting operation thereof in the lifting conveyor in that the lifting fingers 9 are each provided with one or several carrying sleeves 9a which are mounted on them for movements of rotation relative to them.This sleeve has the effect that during the swivel movement of the respective lifting finger 9, during which this finger would, due to the horizontal component of its movement, actually slide on the downwardly directed surface of the wafer leaf resting thereon, which might lead to impairments if the formation of this surface is liable to being damaged, the respective wafer leaf is now only linearly supported in that, although the respective horizontal component of the movement of the lifting finger relative to the wafer leaf surface cannot be eliminated, this movement does not however lead to a sliding movement but the horizontal locality change of the line supporting the respective wafer leaf is brought about by a rolling movement, in that the respective carrying sleeve 9a simply rotates on the associated lifting finger 9. Forthe rest, there are furthermore provided a few supporting rollers 8 which support the wafer leaf in its starting position for the joining to the desired wafer block from the bottom and which facilitate the handling of wafer leaves which are extremely thin-walled and/or particularly large-sized and/or are particularly highly loaded by the filling layer weight in that they prevent its lateral edge zones, which are free for the operative engagement of the lifting fingers 9 of the lifting conveyor 2, from sagging laterally.

it is evident that, also in other respects, the device works in a manner that cannot be compared with known wafer block formation methods. A comparison of the preferred exemplified embodiment shown in Figures 1 to 3 with the known wafer block formation method according to DE OS 2 809 642 shows that in this exemplified embodiment of the invention the wafer block formation is indeed also effected on a level that is higher than the level on which the wafer leaf delivery occurs by means of the feeding conveyor but that it is not effected by adding the individual wafer leaves from the bottom to the wafer cover leaf, which has been lifted to the position of joining by the lifting conveyor, or the preceding formed partial wafer block but is effected by superimposing the wafer cover leaf or the formed partial wafer block on the next wafer leaf that has been delivered to a starting position for the wafer block formation. Correspondingly, the wafer block removal level is also higherthan the wafer leaf delivery plane. However, compared to the wafer block formation method known from DE OS 2323 646, the exemplified embodiment of the invention shown in Figures 1 to 3 differs not only with respect to the method and location of joining the individual wafer leaves to the desired wafer block but also with respect to the removal level of the completed wafer block. Although they are not necessary in respect of the general principle of the invention, both differences allow particularly extensive shortenings of the production time.

Also in another respect, there is a difference, which is important for achieving the desired savings in time, from the known wafer block formation methods. This difference lies in the procedural coupling and conduction of the individual conveyor movement cycles. In the procedural method known, for example from DE OS 2 323 646, the first wafer leaf is lifted through the lifting star wheels of the lifting conveyor, stays in the highest lift position until the next wafer leaf has been delivered to the position of readiness for the joining by means of the feeding conveyor, and is then lowered on the wafer leaf waiting on the level of the feeding conveyor and is joined together with this latter so as to form a wafer block or a partial wafer block.If a complete wafer block with a desired number of only two wafer layers with an interposed filling layer is involved, then this wafer block is now removed on the level of the feeding conveyor, because this happens by this conveyor, and simultaneously with the removal movement, that is to say both simultaneous locally and with respect to speed and with respect to the speed pattern, the next wafer leaf located on the feeding conveyor is delivered to the starting position for the joining of the next wafer block. However, if a formed partial wafer block is involved, then this block is once more lifted by means of the lifting conveyor, has again to wait in the highest lift position until another wafer leaf has been delivered to the position of readiness by means of the feeding conveyor, and is then lowered in the described manner.This process may be repeated several times until the completed wafer block is transported away in the described manner and the first wafer leaf of the next wafer block is delivered simultaneously, under the same conveying movement conditions, to the starting position for the joining to the desired wafer block.

The position is basically different in the present device even without referring, to begin with, to the specific case of the preferred construction of a device according to the invention with four lifting fingers for each lifting star wheel of the lifting conveyor. Here, too, the first wafer leaf, which is intended as the wafer cover leaf, in the wafer leaf succession intended for the desired wafer block is delivered on the feeding conveyor to its starting position for the joining and is lifted in the same way by means of the lifting conveyor. Here, too, the raised wafer leaf waits in the lift position until the next filling-coated wafer leaf has been delivered to the position of readiness for subsequent lifting.In a manner that is similar to the known wafer block formation method, the wafer cover leaf is now also lowered on the wafer leaf which rests on the feeding conveyor and is provided with a filling layer. But now the removal of the formed wafer block is not directly subsequently effected but this block is first once more lifted to the lifting position and is only thereafter transported away, the delivery of the wafer cover leaf of the next wafer block to be formed to the starting position for the joining occurring simultaneously with this removal of the wafer block thus formed.In addition to the difference in the movement sequence, in that another lifting operation is inserted between the lowering of the wafer cover leaf for the formation of the wafer block and the removal thereof, another difference in the device lies in that, although the removal of the wafer block and the delivery of the wafer cover leaf of the next wafer block to be formed are effected at the same time, the two conveying movements however do not necessarily commence at the same time, nor is the speed of conveyance or the speed pattern in time necessarily the same.Although the arrangement provides for an additional movement cycle in the form of the interposed lifting of the completed wafer block, for which a corresponding time is required, it has surprisingly turned out that, due to the disengagement of the removal of the formed wafer block from the delivery of the first wafer leaf of the next wafer block to be formed, there is nevertheless provided the possibility of realising considerable savings in time.

In addition, with a skilful development of the lifting conveyor to be used in the device according to the invention, for example in the exemplified embodiment of the invention comprising a known 'per se' lifting conveyor, on which however respectively four lifting fingers are provided for each lifting star wheel in the suitable described association, a proportion of the lowering movement that is necessary for the joining can be utilised for other purposes, in that the lower filling-coated wafer leaf of this wafer block is moved to meet the movement of lowering of the wafer cover leaf and thus only a proportion of the joining movement has to be overcome as lost time, and this not as part of the lifting movement but rather as a part of the lowering movement, because evidently the interposed lifting movement of the lower filling-coated wafer leaf is continued unchanged and, following a partial lowering of the water cover leaf, takes this up again to the lifted position.

The joining of further filling-coated wafer leaves with the partial wafer block formed in the manner just described is effected in the same way if the desired wafer block is to have a number of wafer leaf layers that exceeds the wafer cover leaf and a wafer leaf joined thereto with a filling layer located inbetween. The described process, with its illustrated movement cycles, is repeated accordingly.

Another difference, which is directed at a considerable saving in time, from known wafer block formation methods, for example in comparison with DE OS 2 323 646, lies in that, due to the described disengagement of the removal of the formed wafer block from the delivery of the first wafer leaf of the next wafer block to be formed, the arrangement allows for the first time to effect the delivery of the individual wafer leaves of a wafer block to be formed without the need for the preceding wafer leaf that has been lifted in the lifting conveyor, for example the wafer cover leaf of the wafer block to be formed, or the preceding completed wafer block to stay in the lifted position. On the contrary, in the present device, it has become possible to begin, and even to complete, the delivery operation for the next wafer leaf while the lifting conveyor is still in motion.By this means, too, it is possible to achieve time gains which are not inconsiderable. However, for this special case of the conduction of the method there must be observed certain marginal conditions. For example, the wafer leaf that is to be brought to its starting position forthe joining must not run in until the lifting star wheel 2b has rotated through at least an angle of rotation for which the ratio of the actual height of lift to the maximum height of lift corresponds to the ratio of the sum of the wafer leaf thickness and half the lifting finger diameter and, in the event of a carrying sleeve 9a being provided on the respective lifting finger 9, or half the carrying sleeve diameter d to half the lifting star wheel diameter or to the distance c of the lifting finger axis 9' from the pivot 2a of the lifting star 2b.On the other hand, the entry of the fresh wafer leaf to be delivered during the lifting star wheel movement must be completed before the lifting star wheel 2b has at the most rotated through such an angle for which the ratio of the difference between the actual height of lowering and the maximum height of lift to the maximum height of lift corresponds to the ratio of the sum of the wafer leaf thickness and half the lifting finger diameter and, in the event of a carrying sleeve 9a being provided on the lifting finger 9, half the carrying sleeve diameter d to half the lifting star wheel diameter or to the distance c of the lifting finger axis 9' from the pivot 2a of the lifting star wheel 2b. What has been said here in respect of one lifting star wheel applies of course identically to all the other lifting star wheels of the same lifting conveyor 2.

Furthermore, the delivery speed for the wafer leaves must be so co-ordinated with the speed of rotation of the lifting fingers 9 that, for a given rotational speed of the lifting fingers 9, the wafer leaves are each delivered at a speed that corresponds to at least the ratio of the wafer leaf length in the delivery direction A two the difference between the angle of the quadrant and the angle for which the ratio of the projection of half the unit circle diameter, which forms its one side, on the perpendicular line on its other side to half the unit circle diameter corresponds to the ratio of the sum of the wafer leaf thickness and half the lifting finger diameter d to the distance c of the axis 9' of the respective lifting finger 9 from the axis of rotation 2a of its rotational movement. If the delivery speed of the wafer leaves is fixed, which procedurally may well be the case, then for such a predetermined delivery speed of the wafer leaves, the lifting fingers 9 should be moved at a rotational speed that at the most corresponds to the product of the ratio of this delivery speed to the length of the wafer leaves and the difference between the quadrant angle and the angle for which the ratio of the projection of half the unit circle diameter, which forms its one side, on the perpendicular line of its other side to half the unit circle diameter corresponds to the ratio of the sum of the wafer leaf thickness and half the lifting finger diameter d to the distance c of the axis 9' of the respective lifting finger 9 from the axis of rotation 2a of its rotational movement.

With respect to construction technique, these limits result in that the lifting fingers 9 must be respectively arranged at a distance c of their axes 9' from the axis of rotation 2a of their rotational movement that corresponds at least to the square root of the product of the square root of two and the sum of the thickness of the delivered wafer leaves and half the lifting finger diameter, and in the event of carrying sleeves being provided half the carrying sleeve diameter d. On the other hand, the lifting fingers each have to have a lifting finger diameter d that corresponds at the most to the ratio of the product of the square root of two and the square of the distance c of the axis 9' of the respective lifting finger 9 from the axis of rotation 2a of its rotational movement to the thickness of the delivered wafer leaves.Of particular importance is, for the rest, the limiting condition that the axes of rotation 2a for the rotational movement of two lifting fingers, which are arranged in succession in the direction of delivery A of the wafer leaves, or of the lifting star wheels 2b which carry these fingers, are arranged at a distance 1 that corresponds at least to the difference between the length of the delivered wafer leaves and the ratio of the sum of the thickness thereof and half the lifting finger diameter d to the distance c of the axes 9' of the lifting fingers 9 from the associated axis of rotation 2a for the rotational movement of the respective lifting finger 9 or the axis of rotation 2a of the associated star wheel 2b.If these limiting conditions are observed, then the total time required for the lifting movement and the lowering move ment which, as made possible by the device, then directly follows without any delay can be utilised for the delivery operation of the next wafer leaf to the position of readiness thereof for its following lifting process. However, it must then also be ensured that the delivery of this next wafer leaf to its starting position 22 (Figure 1 ) for the joining or for the initiation of the lifting operation is completed before there can come about a collision of the lifting finger of the lifting star wheel 2b at the inlet end, the right starwheel in Figure 1,which finger is being lowered, with the tail end of the delivered wafer leaf. And this is ensured by the afore-described limiting conditions.It is evident that under these circumstances the arrangement could be extended in such a way that the entire delivery process is in time accommodated in the time that is required for the performance of the lifting process of the lifting conveyor. And this is indeed possible without impairing thereby the freedom of choice concerning the program sequence in time of the individual conveying speeds that are involved.

For increasing the reliability of the procedural sequence by automatically occurring control with further advantages for shortening the total production time per wafer block formation cycle, there is provided in connection with the described exemplified embodiment of the invention a control unit, which is only diagrammatically shown in Figure 1 and which is designated 30 as a whole. The dashdotted border of this control unit 30 in a purely diagrammatical representation shows, in the lower area, the operating state for a trouble-free conveying operation and, in the upper area, the same device in an operating state which occurs whenever there has come about for any reason a wafer leaf build-up in front of the lifting conveyor 2 as regards the flow of conveyance.

The control unit 30 shown is constructed as a combined multi-purpose device for monitoring and automatic switching-off. It includes the scanning probe 14 which is arranged in the conveying path of the feeding conveyor 1 a short distance from the inlet of the lifting conveyor 2. For adjustment or for any required adaptation to different procedural parameters, which include, for example, the length of the wafer leaves delivered on the feeding conveyor 1, this scanning probe 14 is designed so as to be displaceable along the conveying path 21 of the feeding conveyor 1. As described at the beginning, it serves for detecting the proper delivery of a wafer leaf to a predetermined point in the conveying path 21 of the feeding conveyor 1 and for starting up the lifting conveyor 2 whenever a correct delivery of a wafer leaf has occurred.

For this purpose, the scanning probe 14 is operatively connected to a switching element of the control unit 30, which element is constructed, for example, as a closing contact and which is also designated 14. This switching element 14 is arranged in the energy supply path for all the drives of the three conveyors, namely, on the one hand, the drive motor 31 forthe feeding conveyor 1, which transmits its rotational movement, for example through a chain drive 31 a, to the shafts of the feeding conveyor 1 and also the shaft of the supporting rollers 8 (Figure 2) and may be subjected, for example, to the function of a time programming unit 34, and furthermore the stepping motor 32 for the lifting conveyor 2, whose move ment is transmitted through the kinematic drive connection 32a, 32b to the shafts 2a of the lifting star wheels 2b of the lifting conveyor 2, and finally the.

stepping motor 33 of the withdrawal conveyor 3, whose movement is transmitted through the kine matic drive connection 33a, 33b to, for example, the shaft 3a of the withdrawal conveyor 3 belt or chain drive deflection pulley which is farthest to the left in Figure 1. These motors are diagrammatically shown in Figure 1 as being arranged downstream of the control unit 30. It is shown that there may be associated with the drive 33 for the withdrawal conveyor 3 a control unit 18 for the speed pattern as a program transmitter.

In the energy supply path, which is provided downstream of the switching element 14, to the drive motor 33 for the withdrawal conveyor 3, there is arranged a counting mechanism 16 which detects the number of wafer leaves delivered on the con veying path 21 of the feeding conveyor 1 in depend ence on the scanning function of the scanning probe 14 and emits or passes on a starting pulse for the drive motor 33 of the withdrawal conveyor 3 when the number of delivered wafer leaves desired for a specific wafer block and preset to the counting mechanism 16 has been reached.Expediently, this counter is operatively arranged upstream of the time program transmitter 18 for the speed pattern of the removal movement of the withdrawal conveyor 3 so that whenever no starting pulse, and thus no energy supply, is given to the drive motor 33 of the withdrawal conveyor 3 the time program transmitter need not be in action.

An automatic control is provided for the withdraw al conveyor 3. This control comprises in the control unit unit 30 a speed modulator 17, which is designed in a suitable manner, for reducing the speed of the pushing finger movement of the withdrawal con veyor 3, and which, being downstream of the counter 16, is arranged in the energy supply path for the drive 33 of the withdrawal conveyor 3 and can be switched into the energy supply path through a switching element 6a or else be by-passed through a by-pass line. Downstream of the by-passing connec tion, a switching-off element 6b is furthermore arranged in the energy supply path to the drive 33 of the withdrawal conveyor 3.These switching ele ments 6a and 6b shown in the block diagram of the control unit 30 are once more shown in detail in their constructional arrangement and association with the withdrawal conveyor 3 in connection with this latter.

For example, two switching elements 6a and 6b may be arranged, staggered at an appropriate distance from each other, at a suitable point along the movement path of the belt or chain drive of the withdrawal conveyor 3, in the exemplified embodi ment shown in the zone of the deflection pulley of the tensioning station 11, 12, 12a, so that they are operated in a contact-free manner, for example optically and/or opto-electrically or opto electronically, in that a switching element following the movement of the withdrawal conveyor 3 passes them. As the switching element, there is provided in the exemplified embodiment shown respectively one switching lug 13 which is arranged on one of the pushing fingers 5 respectively.If, on account of the starting pulse given to the drive 33 of the withdrawal conveyor 3 as a function of the response of the scanning probe 14 and the counter 16, a pushing finger 5 has in the described manner brought a completed wafer block, with an acceleration that occurs according to the time program specified by the program transmitter 18 and is preferably as high as possible, to preferably the maximum removal speed and has transmitted it to the onward transpor tation conveyor 7 at this speed, there must now be brought about a stoppage of the withdrawal con veyor 3 since the next pushing finger 5 has to be brought to the position of readiness for the removal of the next wafer block to be formed.At the same time, the pushing finger 5 which has just transferred a completed wafer block to the onward transportation conveyor 7 has to be brought exactly into its compartment formation position, which is shown by way of example on the left-hand side in Figure 1 and in which it is aligned with the stop 20, which is fixedly arranged in the conveying path 21 of the feeding conveyor 1, and forms, together with this stop, the guide for the lifting movement of the wafer leaves in the lifting conveyor 2.However, for this purpose, it is necessary to reduce the high conveying speed of the withdrawal conveyor 3 in a suitable manner so that the belt or chain track carrying the pushing fingers 5 is brought to a standstill in such good time that the pushing fingers upstream and downstream of the conveying path 23 of the withdrawal conveyor 3 have taken up their predetermined waiting or working positions. For this purpose, the switching element 6a is movementwise arranged upstream of the switching element 6b so that it is actuated earlier than the switching element 6b by the switching lug 13 of the third pushing finger 5 guided past it.By this means, the switching element 6a, which is shown as an opening contact, is so actuated in the control unit 30 that the energy supply by-passing the speed modulator 17 is interrupted and the energy to the drive 33 of the withdrawal conveyor 3 is now fed thereto through the speed modulator 17 which provides for a speed reduction, occurring in a suitable manner, on the travel path of the switching lug 13 from the switching element 6a to the switching element 6b or during the time that is available to this end respectively.

When the pushing finger 5 then passes, with its switching element 13, the switching element 6b, this latter is actuated and interrupts the energy supply to the drive 33 of the withdrawal conveyor 3 completely. In this way, there is ensured a braking of the movement of the withdrawal conveyor 3 which occurs according to a desired time pattern, treats the wafer block gently and brings the pushing fingers 5 concerned exactly to the desired positions.

However, it should be pointed out that the automatic switching-off means of the withdrawal conveyor 3 may be designed in a different manner. For example, instead of only two switching elements 6a, 6b, there may be provided more switching elements and/or these switching elements may be arranged at different points along the revolving path of the belt or chain drive of the withdrawal conveyor 3. Furthermore, the material conveyed thereon, namely the completed wafer block to be transported away, may itself carry out the function of the actuating element for the switching elements. And, finally, there may be advantageously provided a switching means which is not dependent on the movement path of the belt or chain track of the withdrawal conveyor 3 but is dependent on the movement cycle of a stationary component of the withdrawal conveyor 3, such as the angle of rotation of the axis or shaft 3a of a deflection pulley thereof, and which is shown as an alternative in a diagrammatical representation on the top left-hand side in Figure 1. This switching means comprises, instead of the switching elements 6a, 6b arranged along the movement path of the belt or chain track of the withdrawal conveyor 3, a switching disc 6 which is non-rotatably arranged on the shaft 3a of the withdrawal conveyor 3 and has a recess 6'.Within the range of rotation of this recess 6' of the switching disc 6, there is arranged a switching element 6" which is designed as a scanning probe. Whenever the recess 6' passes the scanning probe 6", a corresponding switching-off pulse is given to the control unit 30, by means of which or as a function of which the energy supply to the drive 33 of the withdrawal conveyor 3 is switched off. This recess 6' thus has the already described function of the switching element 6a.However, the switching disc 6 may have at least another recess which is also guided past the scanning probe 6" in the course of its rotational movement and then causes the energy supply to the drive 33 of the withdrawal conveyor 3 to be switched from the branch that by-passes the speed modulator 17 to the branch containing the speed modulator 17 and which thus had the already described function of the switching element 6b. To illustrate this, the scanning probe 6" in Figure 1 is connected through dashdotted lines symbolising the operative connection, with the aid of the corresponding operative line connections of the switching elements 6a and 6b,to the control unit 30.It is evident that this design of the automatic switching-off means of the withdrawal conveyor 3 ensures an even more exact observation of the positioning of the pushing fingers 5 to their desired positions of readiness or operation, even for prolonged operating times, than would be possible in a means that is dependent on the movement path of the belt or chain drive 4 of the withdrawal conveyor 3 and which would be dependent on the inevitable fatigue and elongation phenomena of such a drive and on the re-tensioning movements required as a result. Due to the thus also improved accuracy of the association in time of the individual movement cycles, this also contributes to a shortening of the production time per wafer block formation cycle and thus to an increase in the throughput rate of the device.Special emphasis is laid on the fact that, due to the automatic control provided, a further gain in time is achievable in that the wafer leaves delivered on the feeding conveyor 1 can run in in close succession, which was not considered allowable until now, that is to say the spaces between them are extremely small.

The control unit 30 furthermore incorporates an anti-congestion means. This also includes the scanning probe 14 already described. However, it furthermore comprises yet another scanning probe 15 which is arranged at a distance from the former upstream in the conveying path 21 of the feeding conveyor 1 and which is operatively connected to a switching element of the control unit 30, which element is also designated 15. This switching element 15 is connected upstream of the switching element 14, which is in operative connection with the other scanning probe 14, in the control unit 30 in the energy feed path for all the drives 31,32 and 33 of the conveyors 1,2 and 3. In the diagrammatical block representation of Figure 1, it is shown as an opening contact.When it is actuated, it interrupts the energy supply to the switching element 14 and feeds this supply to a signalling means 19 which is arranged in a parallel energy feed path.

If there occurs a build-up of wafer leaves in the conveying path 21 of the feeding conveyor 1,then this causes both scanning probes 14 and 15 to be covered, that is to say both report the presence of a wafer leaf. This, in turn, leads to the switching element 15 switching from its position shown at the bottom in the block diagram of the control unit 30 in Figure 1 to the position shown at the top, with the switching element 14 in the energy conduction position, in other words if a wafer leaf is present beneath the scanning probe 14. The consequence thereof is that all the functions of all the drives 31, 32 and 33 of the conveyors 1,2 and 3 are switched off by this means and the signalling means 19 is furthermore applied to energy supply, by which means attention is drawn to a wafer leaf build-up that has occurred on these.

It is evident that the control unit 30 is only diagrammatically shown in the illustrated block diagram and that its details and partial means are designed in a manner that is well known to someone skilled in the art, without this having to be illustrated in more detail. In particular, it is not necessary for the individual switching andlor control means to be located respectively in the circuit of the actuating energy for the conveyor drives or to be triggerable or actuatable with a correspondingly high energy level; on the contrary, in most cases, it will prove to be more expedient, instead of the construction diagrammatically shown for reasons of a simplified explanation in Figure 1, to effect the actuation triggering of the control unit with its individual partial units in one or several signal energy circuits with electric low tension.The circuitry of a control unit suitable therefor is well known to one skilled in the art.

It will be appreciated that in the described device that successive wafer leaves are joined by a forcibly conducted movement at a speed not dependent on their delivery speed to the start position and the formed block is removed at a speed not dependent on the joining movement nor on the delivery speed.

It is evident that although the invention is shown and has been described with reference to only one exemplified embodiment, it is not confined to this embodiment but that many possibilities are open to one skilled in the art of adapting it, by means of a different combination of its features or the exchange thereof for means of identical effect, to the respective constructional and procedural factors and/or the requirements of an individual case so that an addition to existing plants is possible so as to achieve an improved arrangement. In any event, the arrangement offers the possibility of considerably increasing the throughput rate of wafer blocks to be formed per unit of time in comparison with conventional wafer block formation methods. For example, compared to the throughput rates G-- known devices of the same type, there have been achieved through put rates of formed wafer blocks per u;r,;t of time which are up to double as high and higher, even with considerably larger wafer leaf dimensions and/or more unfavourable conditions of the wafer leaf

Claims (88)

constitution and/or its coating. CLAIMS

1. A method for the production of wafer blocks comprising at least one wafer leaf provided with a filling layer and one wafer cover leaf, in which method these wafer leaves with or without filling layers are successively joined by means of a respec tive forcibly conducted movement at a speed that is not dependent on their delivery speed to a predetermined starting position for the joining to the desired wafer block in a direction that is substantially perpendicular to their delivery direction so as to form the desired wafer block which is then trans ported away from its joining position in order to clear this position for the next wafer block or the first wafer leaf thereof, in which the formed wafer block is transported away at a removal speed that is not dependent on the speed of the joining movement of the wafer leaves with or without filling layers nor the delivery speed thereof to their predetermined start ing position for the joining to the desired wafer block.

2. A method as claimed in Claim 1, characterised in that the formed wafer block is transported away by a form-locking force application.

3. A method as claimed in Claim 1 or Claim 2, characterised in that the formed wafer block is transported away in a supported manner by force application that is not dependent on the delivery movement for the wafer leaves nor on the joining movement thereof.

4. A method as claimed in Claim 3, characterised in that the force application is applied by at least one pushing finger which engages overtheformed wafer block.

5. A method as claimed in any one of the preceding Claims, characterised in that the formed wafer block is transported away on a movement path that differs from the movement path of the delivery movement for the wafer leaves.

6. A method as claimed in any one of the preceding Claims, characterised in that the formed wafer block is transported away in the delivery plane of its wafer leaves.

7. A method as claimed in any one of Claims 1 to 5, characterised in that the formed wafer block is transported away in a plane that is different from the delivery plane of its wafer leaves.

8. A method as claimed in Claim 7, characterised bin that the formed wafer block is transported away in a plane that is lower than the delivery plane of its wafer leaves.

9. A method as claimed in Claim 7, characterised in that the formed wafer block is transported away in a plane that is higher than the delivery plane of its wafer leaves.

10. A method as claimed in any one of the preceding claims, characterised in that the formed wafer block is transported away at a speed that changes according to a predetermined time sequ ence.

11. A method as claimed in any one of the preceding Claims, characterised in that the first wafer leaf of the next wafer block to be formed is delivered at a virtually constant speed.

12. A method as claimed in any one of Claims 1 to 10, characterised in that the first wafer leaf of the next wafer block to be formed is delivered at a speed that changes according to a predetermined time sequence.

13. A method as claimed in any one of the preceding Claims, characterised in that the first wafer leaf of the next wafer block to be formed is delivered simultaneously with the removal of the preceding wafer block.

14. A method as claimed in any one of Claims 1 to 12, characterised in that the first wafer leaf of the next wafer block to be formed is transported away earlier than the commencement of the removal of the preceding formed wafer block.

15. A method as claimed in any one of Claims 11 to 14, characterised in that the wafer leaves which follow the first wafer leaf of wafer block are delivered in the same manner as this first leaf.

16. A method as claimed in any one of the preceding Claims, characterised in that the wafer leaves are each joined, in known 'per se' manner, at a constant joining speed so as to formed the desired wafer block.

17. A method as claimed in any one of Claims 1 to 15, characterised in that the wafer leaves are each joined so as to form the desired wafer block at a joining speed that is reduced in known 'per se' manner towards the moment of joining.

18. A method as claimed in any one of the preceding Claims, characterised in that the joining movement is not imparted to the wafer leaves until they have respectively reached a predetermined position of association for their joining to the desired wafer block.

19. A method as claimed in any one of Claims 1 to 17, characterised in that the joining movement is imparted to the wafer leaves before they have respectively reached a predetermined position of association fortheirjoining to the desired wafer block.

20. A method as claimed in any one of the preceding Claims, characterised in that the wafer block is formed in that its wafer leaves are superimposed one upon the other.

21. A method as claimed in any one of Claims 1 to 19, characterised in that the wafer block is formed in known 'per se' manner in that its wafer leaves are placed one against the other from the bottom.

22. A method as claimed in any one of the preceding Claims, wherein the removal of the formed wafer block is effected in a plane that is different from the delivery plane of its wafer leaves, characterised in that the wafer leaves to be joined to the desired wafer block are each moved against a stationary stop defining a starting position for the joining and, during the course of the joining movement, are moved along it while staying in abutting contact therewith.

23. A method as claimed in any on Df the preceding Claims, characterised in that the wafer leaves are joined to form the desired wafer block by being supported linearly.

24. A method as claimed in any one of the preceding Claims, characterised in that the wafer leaves are joined to form the desired wafer block by being supported in a mannerthat is free from sliding movement.

25. A method as claimed in any one of the preceding Claims, characterised in that the wafer leaves are joined to form the desired wafer block in known 'per se' manner by means of lifting fingers which each carry out a rotational movement around an axis of rotation that is parallel to the direction of delivery of the wafer leaves.

26. A method as claimed in Claim 25, characterised in that the delivery of a wafer leaf is only commenced when the lifting fingers each have passed through an angle of rotation for which the ratio of the actual lift height to the maximum lift height corresponds to the ratio of the sum of the wafer leaf thickness and half the lifting finger diameter to the distance of the axis of the respective lifting finger from the axis of rotation of its rotational movement.

27. A method as claimed in Claim 25 or 26, characterised in that the delivery of a wafer leaf is completed before the lifting fingers each have passed through an angle of rotation for which the ratio of the difference between the actual height of lowering of the respective lifting finger and the maximum lift height thereof to this maximum lift height corresponds to the ratio of the sum of the wafer leaf thickness and half the lifting finger diameter to the distance of the axis of the respective lifting finger from the axis of rotation of its rotational movement.

28. A method as claimed in any one of Claims 25 to 27, characterised in that for a given rotational speed of the lifting fingers, the wafer leaves are each joined to form the desired wafer block at a speed that corresponds to at least the ratio of the wafer leaf length in the delivery direction to the difference between the angle of the quadrant and the angle for which the ratio of the projection of half the unit circle diameter, which forms its one side, on the perpendicular line on its other side to half the unit circle diameter corresponds to the ratio of the sum of the wafer leaf thickness and half the lifting finger diameter to the distance of the axis of the respective lifting finger from the axis of rotation of its rotational movement.

29. A method as claimed in any of Claims 25 to 28, characterised in that for a given delivery speed of the wafer leaves, the lifting fingers are moved at a rotational speed that at the most corresponds to the product of the ratio of this delivery speed to the length of the wafer leaves and the difference between the quadrant angle and the angle for which the ratio of the projection of half the unit circle diameter, which forms its one side, on the perpendicular line of its other side to half the unit circle diameter corresponds to the ratio of the sum of the wafer leaf thickness and half the lifting finger diameter to the distance of the axis of the respective lifting finger from the axis of rotation of its rotational movement.

30. A method as claimed in any one of the preceding Claims, characterised in that the wafer leaves to be joined to the desired wafer block are monitored to the effect whether they have reached a predetermined position in the course of their deiivery movement, preferably a starting position for the joining to the desired wafer block, whereupon the joining movement is then initiated in dependence on the attainment of this predetermined position.

31. - A method as claimed in any one of the preceding Claims, characterised in that the wafer leaves to be joined to the desired wafer block are monitored to the effect whether a predetermined one of them has reached a predetermined position in the course of its delivery movement, preferably a starting position for the joining to the desired wafer block, whereupon the removal movement for the formed wafer block is then initiated in dependence on the attainment of this predetermined position.

32. A method as claimed in any one of the preceding Claims, characterised in that the removal movement of the formed wafer block is terminated by this wafer block itself or in dependence on the movement of a monitoring element which corresponds to its movement.

33. A device for the production of wafer blocks comprising at least one wafer leaf provided with a filling layer and one wafer cover leaf, which are successively joined by a lifting conveyor, which imparts to them a forcibly conducted movement in a direction that is substantially perpendicular to their delivery direction at a delivery speed impressed on them by a feeding conveyor, so as to form the desired wafer block which is then transported away from its joining position by means of a withdrawal conveyor in order to clear this position for the following wafer block or the first wafer leaf thereof, comprising a withdrawal conveyorwhich can be driven at a speed that is independent of the joining speed of the lifting conveyor and also of the delivery speed of the feeding conveyor.

34. A device as claimed in Claim 33, character ised by a withdrawal conveyor which engages in a form-locked manner on the formed wafer block.

35. A device as claimed in Claim 33 or 34, characterised by a withdrawal conveyor which sup ports the formed wafer block by a force application that is independent of both the delivery movement for the wafer leaves and the joining movement thereof.

36. A device as claimed in Claim 35, character ised in that the withdrawal conveyor comprises at least one pushing finger which engages beneath the formed wafer block.

37. A device as claimed in any one of Claims 33 to 36, characterised in that the withdrawal conveyor has a movement path that is different from the movement path of the delivery movement for the wafer leaves.

38. A device as claimed in any one of Claims 33 to 37, characterised in that the withdrawal conveyor is formed by an endless belt or chain track, on which there is arranged, so as to project therefrom, at least one pushing finger for the formed wafer block.

39. A device as claimed in Claim 38, character ised in that three pushing fingers are provided.

40. A device as claimed in Claim 38 or 39, characterised in that the belt or chain track is kept in working tension through a fixed stop.

41. A device as claimed in any one of Claims 33 to 40 and comprising at least one withdrawal pushing finger which engages beneath the formed wafer block, characterised in that the pushing finger is returnable outside the conveying path of the withdrawal conveyor to its position of readiness for the removal of the next wafer block,

42. A device as claimed in any one of Claims 33 to 41, characterised in that the withdrawal conveyor for the removal of the formed wafer block is arranged in the plane of the delivery of the wafer leaves thereof.

43. A device as claimed in any one of Claims 33 to 41, characterised in that the withdrawal conveyor for the removal of the formed wafer block is arranged in a plane that is different from the plane for the delivery of the wafer leaves thereof.

44. A device as claimed in Claim 32, character ised in that the withdrawal conveyor is arranged, with a strand that imparts the removal movement to the formed wafer block, beneath the plane for the delivery of the wafer leaves thereof.

45. A device as claimed in Claim 43, character ised in that the withdrawal conveyor is arranged, with its strand that imparts the removal movement to the formed wafer block, above the plane for the delivery of the wafer leaves thereof.

46. A device as claimed in any one of Claims 33 to 45, characterised in that there is provided a control unit for the drive of the withdrawal conveyor at a speed that changes over the removal path of the formed wafer block according to a predetermined time pattern.

47. A device as claimed in any one of Claims 33 to 46, characterised in that the feeding conveyor for the delivery of the first wafer leaf of the next wafer block to be formed is operable at a virtually constant speed.

48. A device as claimed in any one of Claims 33 to 46, characterised in that the feeding conveyor for the delivery of the first wafer leaf of the next wafer block to be formed is operable at a speed that changes to a predetermined time pattern.

49. A device as claimed in any one of Claims 33 to 46 and 48, characterised in that there is provided a control unit for the drive of the feeding conveyor at a speed that changes over the delivery path of the first wafer leaf of the next wafer block to be formed according to a predetermined time pattern.

50. A device as claimed in any one of Claims 33 to 49, characterised in that the first wafer leaf of the next wafer block to be formed can be delivered simultaneously with the removal of the formed wafer block.

51. A device as claimed in any one of Claims 33 to 49, characterised in that the first wafer leaf of the next wafer block to be formed can be delivered earlier than the commencement of the removal of the preceding formed wafer block.

52. A device as claimed in any one of Claims 46 to 51, characterised in that the wafer leaves which follow the first wafer leaf of a wafer block can be delivered in the same manner as this leaf.

53. A device as claimed in Claim 52, characterised in that there is provided a control means for the drive of the feeding conveyor at a speed that changes over the delivery path of all wafer leaves of a wafer block to be formed according to a predetermined time pattern.

54. A device as claimed in any one of Claims 33 to 53, characterised in that there is provided a lifting conveyor for joining the wafer leaves to the desired wafer block at a constant joining speed.

55. A device as claimed in any one of Claims 33 to 53, characterised in that there is provided a lifting conveyor for joining the wafer leaves to the desired wafer block at a joining speed that is reduced towards the moment of joining.

56. A device as claimed in any one of Claims 33 to 53, characterised in that there is provided a predetermined position of association for the wafer leaves to be joined to the desired wafer block, only after the attainment of which position the lifting conveyor can be brought into a respective operative connection with these so as to impart to them the respective movement of joining.

57. A device as claimed in any one of Claims 33 to 55, characterised in that the lifting conveyor can be brought into operative engagement with the wafer leaves to be joined to the desired wafer block prior to their reaching a predetermined position of association for their joining to the desired wafer block, so as to impart them the respective movement ofjoining.

58. A device as claimed in any one of Claims 33 to 57, characterised in that as the lifting conveyor there is provided a conveyor which places the wafer leaves to be joined to the desired wafer block one above the other from the top.

59. A device as claimed in any one of Claims 33 to 57, characterised in that as the lifting conveyor there is provided a known 'per se' conveyor which joins the wafer leaves to be joined to the desired wafer block in layers from the bottom.

60. A device as claimed in any one of Claims 33 to 59 and in which the removal of the formed wafer block occurs on a plane that is different from the plane for the delivery of its wafer leaves, characterised in that there is provided a stationary stop which defines a starting position for the joining of the wafer leaves to be joined to the desired wafer block and against which the wafer leaves are each moved and, in the course of the joining movement are moved along it while staying in abutting contact therewith.

61. A device as claimed in Claim 60, characterised in that the stationary stop has an extension which is aligned with it and can be removed from the removal path of the withdrawal conveyor.

62. A device as claimed in Claim 61, characterised in that the stop extension can be removed from the removal path of the withdrawal conveyor by a swivel movement.

63. A device as claimed in Claim 61 or 62 and comprising a withdrawal conveyor formed by an endless belt or chain track and on which there is arranged, so as to project therefrom, at least one pushing finger, characterised in that the stop exten sion is arranged on this belt or chain track of the withdrawal conveyor.

64. A device as claimed in Claim 63, characterised in that the stop extension is respectively formed by the wafer-block-remote rear of a pushing finger.

65. A device as claimed in Claim 64, characterised in that the respective wafer-block-remote rear of the pushing finger which transports the preceding formed wafer block away, is operative as the stop extension for the formation of the next wafer block.

66. A device as claimed in any one of Claims 33 to 65, characterised by a linear support of the wafer leaves to be joined to the desired wafer block during the joining process.

67. A device as claimed in any one of Claims 33 to 66, characterised by a slide-movement-free support of the wafer leaves to be joined to the desired wafer block during the joining process.

68. A device as claimed in Claim 66 or 67, characterised in that for the support of the wafer leaves to be joined to the desired wafer block there are provided supporting fingers which engage beneath these from their side and which are approximately parallel to their plane.

69. A device as claimed in Claim 68, characterised in that the supporting fingers each have a carrying sleeve which is mounted on them for a rotational movement relative to them.

70. A device as claimed in any one of Claims 33 to 69, characterised in that as the lifting conveyor there is provided a conveyor comprising lifting fingers which each carry out a rotational movement around an axis of rotation that is parallel to the delivery direction of the wafer leaves.

71. A device as claimed in Claim 70, characterised in that the lifting fingers are each arranged at a distance of their axes from the axis of rotation of their rotational movement that corresponds to at least the square root of the product of the square root of two and the sum of the thickness of the delivered wafer leaves and half the lifting finger diameter.

72. A device as claimed in Claim 70 or 71, characterised in that the lifting fingers each have a lifting finger diameter that corresponds at the most to the ratio of the product of the square root of two and the square of the distance of the axis of the respective lifting finger from the axis of rotation of its rotational movement to'the thickness of the delivered wafer leaves.

73. A device as claimed in any one of Claims 70 to 72, characterised in that the axes of rotation for the rotational movement of two lifting fingers, which are arranged in succession in the delivery direction of the wafer leaves, are arranged at an interval that corresponds at least to the difference between the length of the delivered wafer leaves and the ratio of the sum of the thickness thereof and half the lifting finger diameter to the distance of the axes of the lifting fingers from the associated axis of rotation for the rotational movement of the respective lifting finger.

74. A device as claimed in any one of Claims 33 to 73, characterised in that there is provided a monitoring means by means of which the wafer leaves to be joined to the desired wafer block can be monitored to the effect whether they have reached a predetermined position in the course of their delivery movement, preferably a starting position for their joining to the desired wafer block, and by means of which the lifting conveyor is then actuatable in dependence on the attainment of this predetermined position.

75. A device as claimed in any one of Claims 33 to 74, characterised in that there is provided a monitoring means by means of which the wafer leaves to be joined to the desired wafer block can be monitored to the effect whether a predetermined one of them has reached a predetermined position in the course of its delivery movement, preferably a starting position for the joining to the desired wafer block, and by means of which the withdrawal conveyor is then actuatable in dependence on the attainment of this predetermined position for the removal of the formed wafer block.

76. A device as claimed in Claim 74 or 75, characterised in that the monitoring means comprises a scanning probe which is arranged in the conveying path of the feeding conveyor and which preferably works in a contact-free manner.

77. A device as claimed in Claim 76, characterised in that the scanning probe is arranged so as to be displaceable along the conveying path of the feeding conveyor.

78. A device as claimed in any one of Claims 33 to 77, characterised in that there is provided an automatic switching-off means for the withdrawal conveyor, which means is actuatable by the wafer block, which is to be transported away by this latter, itself or in dependence on the movement of a monitoring element that corresponds to its movement.

79. A device as claimed in Claim 78, characterised in that the automatic switching-off means comprises at least one switching means which is arranged in the conveying path and/or in the return path of the withdrawal conveyor and which is actuatable by a switching element that is moved by the withdrawal conveyor and which produces a switching-off pulse for the withdrawal conveyor.

80. A device as claimed in Claim 79, characterised in that the automatic switching-off means comprises a switching-over means which is arranged conveyancewise upstream of the switch ing-off means producing the switching-off pulse for the withdrawal conveyor and which is actuatable by the same switching element moved by the withdrawal conveyor and which produces a switchingover pulse for reducing the removal speed to a lower conveying speed of the withdrawal conveyor.

81. A device as claimed in Claim 79 or 80, characterised in that the switching means, and/or the switching-over means work in a contact-free manner, for example optically or opto-electrically or opto-electronically, and in that the switching element is formed by the removed wafer block.

82. A device as claimed in Claim 79 "r 80, characterised in that the switching means and/or the switching-over means work in a contact-free manner, for example optically or opto-electrically or opto-electronically, and in that the switching element is formed by a switching lug which is arranged on the withdrawal conveyor, preferably on the pushing finger or each of the pushing fingers thereof.

83. A device as claimed in Claim 78, characterised in that the automatic switching-off means comprises a switching means which is independent of the conveying path and/or the return path of the withdrawal conveyor but which is dependent on the movement cycle of a stationary component of the withdrawal conveyor, the angle of rotation of the axis or shaft of a deflection pulley.

84. A device as claimed in Claim 83 and comprising a withdrawal conveyor which is formed by an endless belt or chain drive that has at least one pushing finger for the formed wafer block, characterised in that the switching means comprises a switching disc, which is arranged on an extension of a shaft or axis of a deflection pulley of the withdrawal conveyor and is provided with at least one recess, which is provided in a specified angular association, and a stationarily arranged scanning probe, by means of a switching-over and/or switching-off pulse for the removal speed can be produced.

85. A device as claimed in any one of Claims 33 to 84, characterised in that there is provided an anti-congestion means, by means of which a warning signal can be emitted and/orthe functions of all the conveyors can be switched off if there is a build-up of wafer leaves in the conveying path of the feeding conveyor.

86. A device as claimed in Claim 85, characterised in that the anti-congestion means comprises a scanning probe, which is arranged in the conveying path of the feeding conveyor and preferably works in a contact-free manner, and another scanning probe, which can be adjusted according to the length of the wafer leaves to be conveyed in the direction of conveyance of the feeding conveyor in its distance from the former along the conveying path of the feeding conveyor, and produces, in the event of both scanning probes being actuated simultaneously, a trigger pulse for the signalling and/or for the switching-off of the functions of all the conveyors.

87. A method for the production of wafer blocks substantially as hereinbefore described.

88. A device for the production of wafer blocks substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.