Said problem occurs particularly with articles which cannot be stacked or nested easily. An example hereof are easy to open covers which are used to close drinks cans and comprise a tear-off portion which is bounded by a weakening line and can form a drinking or pouring open- ing. Such covers are generally not nestable, or hardly so, while furthermore a stable stacking is hardly possi- ble as a consequence of the asymmetrical form caused by the presence of a tab and the small active stacking depth. Such articles must therefore be transported unin- terruptedly in connected flows such that they are perma- nently subjected to a sufficiently great axial pressure, particularly in order to prevent tipping over of the first and last cover of a flow.

In order to be able to compensate adequately for short operational stoppages of the unpacking machine (and possibly the cover manufacturing machine), a sufficiently large buffer capacity must be available between the unpacking or production machine and the processing de- vice. Use could be made of relatively long conveyor belts. Such conveyor belts have the drawback that they occupy a large horizontal area and that specific measures

are moreover neeessary to ensure that the articles cannot tip over.

The object of the invention is to provide a device which is capable of providing a buffer stock of any desired dimensioning, wherein the risk of articles tip- ping over is practically wholly precluded.

In respect of the above, the invention provides a device for forming a buffer stock of mutually oriented articles, for instance stackable or nestable articles, such as beakers, or plate-like or disc-like objects, which device comprises: - supply means for supplying a flow of mutually oriented articles; - a number of at least more or less vertical storage sleeves for accommodating a stack of articles; - discharge means for discharging a flow of mutually oriented articles, wherein the top and bottom sides of the storage sleeves are open and are selectively connect- able to the supply means and/or the discharge means; - supporting means which are present on the under- side of each of the storage sleeves and which are dis- placeable between an open position, in which the articles can be moved out of a sleeve, and a closed position, in which the supporting means can support a stack of arti- cles present in this sleeve; - at least one endless, flexible transporting member for suspended transport of the sleeves; and - a drive for the transporting member, which device comprises a main frame and a sub-frame placed guidably in the main frame, wherein at least the supply means and the discharge means are arranged on the main frame and wherein at least the transporting member and the storage sleeves are arranged on the sub-frame.

The described device according to the invention can, depending on the dimensioning, store any desired quantity of articles. A significant advantage of the device ac- cording to the invention is that it offers a variable capacity. The storage sleeves anyway rotate inside the sub-frame through driving of the transporting member. In addition, the sub-frame is placed guidably inside the

main frame. -This has the result that almost any storage sleeve can perform a rotation movement as well as a translation movement. The buffer capacity is thereby variably adjustable at any moment subject to the require- ments set by the production process.

The device further has the great advantage that due to the vertical placing of the storage sleeves use is made of the force of gravity to prevent articles tipping over, while the occupied horizontal space can remain relatively limited. It is noted here that in most facto- ries, production areas and the like there is generally sufficient vertical space available but that the horizon- tal space is preferably used as little as possible. The buffer stock of the device according to the invention is generally expressed in minutes of production time. By way of illustration, the buffer stock amounts to 12.5 minutes in the case of a device with 50 storage sleeves which can each accommodate 500 covers, assuming that the machines co-acting with the device process approximately 2000 articles per minute. The device according to the inven- tion moreover has a simple construction, functions in reliable manner in practice and is relatively inexpensive to manufacture.

In a first preferred embodiment the device according to the invention comprises at least one holding member which is mounted on the main frame and is movable between a rest position and an operating position, which holding member is adapted to engage in the operating position on the transporting member and/or on at least one storage sleeve for fixedly holding thereof relative to the main frame. This preferred embodiment has the advantage that both the translation movement and the rotation movement of the storage sleeves can be realized using the drive for the transporting member.

Each storage sleeve preferably comprises a block- shaped member and the holding member comprises two plate- like parts which in the operating position engage clam- pingly round the block-shaped member. This holding con- struction is simple and can be given a sufficiently strong mechanical form to hold a storage sleeve fixedly

relative to the-main frame, even when all storage sleeves are entirely filled with articles.

In a further preferred embodiment the supply means and the discharge means are placed approximately in the middle of the main frame on opposite longitudinal sides thereof. The holding member is preferably placed in the region of the supply means and/or the discharge means. In this embodiment an optimal utilization of the variable buffer capacity is possible.

In yet a further embodiment the sub-frame and/or the main frame is tiltable such that the height of the infeed of the supply means respectively the height of the out- feed of the discharge means is adjustable. This is par- ticularly advantageous when the articles are fed manually into the device.

The invention will be described in more detail hereinbelow with reference to the drawing, in which: figure 1 shows a perspective view of a device ac- cording to the invention; and figure 2 shows a part of the device of figure 1 in more detail; and figure 3 shows an alternative embodiment of the device according to the invention.

Figure 1 shows device 1 for forming a buffer stock of mutually oriented articles. Device 1 comprises a main frame 2 in which a sub-frame 3 is placed guidably. Supply means 4 and discharge means 5 are arranged on the main frame. Sub-frame 3 comprises two endless, flexible trans- porting members, preferably in the form of chains 6, 7.

Storage sleeves 8 are arranged suspended more or less vertically on chains 6, 7. Storage sleeves 8 are adapted to accommodate the articles.

In the shown preferred embodiment there is one drive provided which consists of two rotatable shafts 9, 10 which are coupled to chains 6, 7 via a transmission in the form of four tooth wheels 11-14. A motor 15 drives at least shaft 9. Sub-frame 2, including the drive, is guidable inside main frame 2 by means of guide rails 16, 17.

Figure 2 shows in more detail a part of device 1 in the position as depicted in figure 1. For illustrative purposes a number of the storage sleeves 8 are partially filled with articles 18, for instance covers, which are shown schematically. Storage sleeves 8 are each provided with a block-shaped member 19 which also serves to fix the storage sleeves to chain 6. This mounting can take place in many of the ways known in the field, for in- stance with a welded joint. A holding member 20 is ar- ranged on main frame 2. Holding member 20 preferably consists of two plate-like parts 21, 22 which are pivot- able using a hydraulic cylinder 23 between a rest posi- tion (not shown) and the shown operating position. In the shown operating position the plate-like parts 21 and 22 engage clampingly round block-shaped member 19 of a storage sleeve 8. In this manner the relevant storage sleeve is held fast relative to the main frame. This holding can also be realized in alternative manner. The holding member can for instance be a pin (not shown) which in the operating position engages in a link of the chain. In another alternative embodiment (not shown) each storage sleeve 8 is provided over at least a part of the longitudinal side thereof with a slot which is directed toward the chains. The holding member is then plate-like and adapted to be received in a slot of a storage sleeve.

For this purpose the plate-like member has a thickness which is smaller than the width of the slot and the plate-like member is moreover tiltable in a plane lying approximately transversely of the slot.

The operation of device 1 is as follows. Using motor 15 the shaft 9 and, via chains 6, 7 and tooth wheels 11- 14, therewith shaft 10 are rotated. Storage sleeves 8 rotate inside sub-frame 3 as a result. By moving holding member 21 to the operating position one storage sleeve at random is held fast relative to the main frame. Driving with motor 15 then results in sub-frame 3 executing a translation movement inside main frame 2 via guide rails 16, 17. For a better understanding of the operation of the device, this movement can be compared with that of a caterpillar track. The rotation movement as well as the

translation movement of all storage sleeves is thus effected in advantageous manner using a single motor 15.

If desired, a second motor can be provided for realizing the translation movement of sub-frame 3 inside main frame 2 independently of motor 15. Motor 15 then serves exclu- sively for driving of chains 6 and 7 and therefore for the rotation movement of the storage sleeves.

Supply means 4 and discharge means 5 are placed approximately in the middle of main frame 2 on opposite longitudinal sides thereof. Holding member 20 is placed in the region of discharge means 5. A second holding member 24, which is shown only partially, is placed in the region of supply means 4. Two further holding members are preferably arranged at corresponding positions on main frame 2 close to chain 7. Thus is achieved that a storage sleeve 8 can be held fast in the region of supply means 4 and in the region of discharge means 5. In the first case approximately all wholly or partially empty storage sleeves 8 can then be filled. Conversely, in the second case approximately all wholly or partially filled storage sleeves 8 can be emptied. Between these two extremes are a large number of other adjustment options, each with its own buffer capacity.

Storage sleeves 8 are preferably provided with a slot 25 on the longitudinal sides thereof. This slot provides access to covers 18 for guiding thereof using guide means during filling and/or emptying of the storage sleeves. The guide means are adapted such that particu- larly the foremost cover is prevented from falling over.

The supporting means for supporting the articles in a storage sleeve preferably comprise a number of, such as three, preferably equidistant support fingers (not shown). Depending on the weight of the articles the chains 6, 7 are supported, for instance using plastic strips, to prevent sagging under the weight of the filled storage sleeves.

Figure 3 shows an alternative embodiment of a device according to the invention. The shown device 101 compris- es all elements discussed above with reference to device 1. Corresponding elements are designated with the same

reference numerals-as used in figures 1 and 2, but with a hundred added. Device 101 comprises a further frame 130 in which main frame 102 is placed tiltably. This ability to tilt enables adjustment of the height of the infeed of supply means 104 respectively the height of the out feed of discharge means 105. Device 103 is hereby also ex- tremely suitable for manual infeed. If desired, the further frame 130 can be omitted and sub-frame 103 can be placed tiltably in main frame 102. This alternative embodiment is not shown.

The invention is not of course limited to the de- scribed and illustrated embodiment but includes any embodiment which falls within the scope of the appended claims.