GB1567498A - Method and apparatus for stacking sheets into bundles - Google Patents

Description

(54) METHOD AND A15'ARA'I'US FOR S'I'ACKING SHEETS IN'I'O BUNDLES (71) We, UNIVERSAL CORRU GATED BOX MACHINERY GMBH, a German Company of Justus-Liebig-Strasse, D-6051 Ober-Roden, Federal Republic of Germany, do hereby declare the invention for which we pray that a patent may be granted to us. and the method by which it is to be performed to be particularly described in and by the following statement: This invention relates to a method and an apparatus for stacking sheets and particularly although not cxclusively to cutouts which have been pirtiaIly glued and folded flat.

A published method and apparatus for stacking glued and folded cutouts counts the cutouts on a conveyor track, delivers them one after the other to a vertically adjustable stack table on which they are deposited in an aligned state, where after a predetermined number of cutouts have been deposited on the stack the next cutout to be delivered is deposited on a support which is independent of and situated above the stack table, until the stack formed below it has been removed from the stack table to another conveyor track. A method and an apparatus of this kind are shown in U.S.

Patent Specification 3,892,168 of Grobman.

In this specification pivotable fingers are situated on the downstream side of the stack table, referring to the direction of delivery of the stacks, which fingers can be introduced into the path of fall of the cutout falling from the conveyor track onto the stack table and can be drawn back out of that path. Above the stack table a blower is provided which subjects the stack to a blast and thus presses the respective uppermost cutout onto the cutouts situated beneath it.

For the purpose of forming stacks consisting of a predetermined number of cutouts the fingers are pivoted out of an upper, retracted waiting position into the path of fall of the cutouts, so that the cutouts continuously delivered now fall onto the fingers. The stack formed under the fingers on the stack table can therefore be ejected in the conveying direction by means of an ejector piston. The piston is then moved back into its starting position, the stack table is raised to its upper starting position, the fingers are drawn back, pivoted upwards, and in this upper position are pulled out into the previously mentioned starting position. Then the fingers are pulled back out of the path of fall of the cutouts, and the partial stack formed on the fingers is deposited on the raised stack table. During subsequent movements of the fingers, which then take place for the completion of the cycle, the stack continues to be formed until the fingers are pivoted back into the path of fall through the transmission of the previously mentioned signal, and so on.

In this arrangement it is a particular disadvantage that a relatively large amount of time is required for the abovementioned cycle of pivoting movements and the movements by which the fingers are pulled in and out. The conveyor track supplying the stack table can therefore only work at a predetermined maximum speed, which must not be exceeded because otherwise a new stack would be formed before the fingers have been brought into the starting position.

With the present usual output of about 18,000 sheets per hour from a cutout producing machine, coupled with the time indicated in the above-mentioned U.S.Patent Specification of 5 seconds for the completion of each cycle, it is clear that with this known stacking machine it is only possible to form counted stacks of 25 sheets or more. It is therefore not possible for stacks containing a smaller number of sheets or cutouts to be formed with accurate counting unless the output of the machine is reduced accordingly.

According to a first aspect of the present invention there is provided a method of continuously stacking sheets into bundles containing a predetermined number of sheets, in which the sheets are delivered in a flow onto a stacking surface so as to form a stack with the sheets one above another and the bundles are removed at the bottom of the stack, wherein each sheet which is to form a bottom sheet of a bundle is delivered to the stack offset from the other sheets so that it rests upon a movable support positioned adjacent the stack, and the movable support is thereaftermoved into the stack so as to support the said bottom sheet and sheets stacked upon it while the bundle beneath the said bottom sheet is removed, after which the bottom sheet is deposited on the stacking surface.

According to another aspect of the present invention there is also provided apparatus for continuously stacking sheets into bundles, including a stacking surface, means for delivering the sheets in a flow and depositing them one above another to form a stack on the stacking surface, means for delivering the sheets in a flow and depositing them one above another to form a stack on the stacking surface, means for selecting whkch of the sheets is to form the bottom sheet of a bundle associated with displacement means for causing the sheet selected as such a bottom sheet to be stacked offset from the other sheets, a movable support arranged to be positioned adjacent the stack above the stacking surface so as to be engaged by said offset bottom sheet and adapted to be moved into the stack so as to support the bottom sheet and sheets stacked above it while a bundle is removed from below the bottom sheet.

With the present invention, it is possible for stacking to take place very much more quickly than in the known method described above. For instance the sheets continuously delivered by a conveyor track, if desired at the maximum delivery speed of the machine, may only be counted and after a pre-selected number has been reached the next sheet is offset slightly in the lateral direction and in the manner indicated so that this laterally offset sheet is the next to be deposited on the movable support, which until that moment had still not made any movement. The support thus engages under the laterally offset sheet, at an edge which is laterally offset in relation to the other sheets when the support is in its normal waiting position, i.e. close to the stack continuously being formed at any given moment. Only when the laterally projecting edge of the offset sheet has been deposited on the support does the latter move to engage under the entire sheet and thus support it completely. During this time the conveyor track is still delivering the cutouts, which are continuously being deposited on the selected sheet carried by the support. At the same time or thereafter, i.e. while a bundle is deposited on the selected sheet, the lowermost sheet may be brought back a distance, corresponding to the offset, by means of a stop, so that all the sheets are deposited, stacked one above the other.

While the selected sheet is supported by the movable support, the counted bundle formed under it is ejected or removed, so that (where the stacking surface or table moves downwardly as the stack height increases) the stacking surface or table can be raised to its initial position and the movable support removed so that the bottom sheet of the next bundle is transferred to the stacking surface and the next cycle proceeds. Unlike the known method described above, the stack table need not be lowered continously, but stepwise, with the result that a more accurately aligned stack may be obtained.

In the apparatus of the present invention, preferably the said movable support is constituted by a plurality of support members carried by one or more endless elongate elements which are moved, under control, past the stack. More preferably there is a pair of parallel endless driven chains each carrying a plurality of blocks constituting the said movable support, the blocks projecting into the stack as the chain moves past the stack in a direction parallel to the direction of offset of the said bottom sheet.

The time required for carrying out a cycle may thus be very substantially reduced compared with known proceses because all that need be required is for the two chains to be driven until the aforesaid blocks have moved from their initial position directly at the side of the stack being formed, to a position entirely in the stack, i.e. in the path of fall of the sheets. The distance between the chains should be so selected that a sheet can freely fall between them when none of the blocks is in the path of fall. Only when the blocks have been brought into the path of fall, through a movement of the chains over a predetermined distance, will the blocks provide support for the sheets. On each chain a plurality of rows of such blocks can be mounted so that for the completion of a cycle the chains need only be moved a fraction of their length. For this reason it is preferable for a portion comprising chain links provided with blocks to be followed by a portion comprising chain links without blocks, the length of the portion corresponding approximately to the width of the stack.

In a preferred embodiment of the apparatus a pair of rollers is disposed in the delivery path of the sheets which is displaceable in a controlled movement to offset the predetermined sheet laterally. The previously mentioned lateral offsetting of the predetermined sheet can thus be achieved very rapidly in a constructionally simple manner.

In addition, it is preferably for pressing down means provided above the stacking table to comprise a driven belt which is inclined to the top of the stack to receive the incoming sheets and which urges the respective uppermost sheet in the stack towards a stop. This pressing down means can work considerably better than the blower in the previously mentioned U.S. Patent Specification. This applies particularly to sheets of smaller size. The method and apparatus of the invention are particularly suitable for continuously stacking glued and flat folded cardboard cutouts, adapted to be unfolded and formed into boxes, into bundles, each containing a predetermined number of cutouts. For example, the be belt of the pressing down means if provided can prevent the glued joint of the respective uppermost carton from opening. The upper flaps of each folded cutout moreoever are pulled towards the stop by the driven belt, so that improved folding of the cutouts is achieved.

Instead of the driven belt, one or more driven rollers may be provided.

Thus by the invention, the maximum output of resent day machines can be retained, while high accuracy of counting may be achieved.

Small stacks can be formed.

The stacker described and claimed herein is suitable for use in the apparatus claimed in our co-pending a plication no. 7524/77 (Serial No. 15674999. The apparatus the subject of 7523/77 is for stacking sheets into bundles and tying the bundles with tying material and is exemplified with reference to the same drawings as those accompanying the present application.

One embodiment of the invention will now be described, by way of example with reference to the accompanying drawings, wherein: Figure 1 shows diagrammatically in side elevation the essential constructional elements of the embodiment; Figure 2 shows the middle portion of the embodiment in a similar view to that of Figure 1, but on a larger scale; Figure 3 is a section on the line III-III of Figure 2; and Figure 4 is a plan view of a modified form of tying unit.

Referring to Figure 1, glued and folded cutouts for boxes pass in the conveying direction 1 from a folding unit (not shown) to a first table 2, on which they are conveyed upwards on an inclined path. For this purpose a driven belt 3 is provided which drives a number of idler rollers 4 which form a conveyor track for the cutouts. Above the row of idler rollers 4 is situated a plate 5 which is suspended on arms 6. The cutouts are therefore conveyed between the upper face of the row of idler rollers 4 and the lower face of the plate 5. The arms 6 are pivotally fastened to a part of the machine frame 7.

The cutouts travelling in a flow along the conveyor track are counted by a photoelectric cell 8. A pair of rollers 9 situated at the end of the conveyor track can be displaced a predetermined distance in a direction at right angles to the plane of the paper in Figure 1 under the control of an electromagnet (not shown). In the view shown in Figure 3 the corresponding direction is towards the right of the paper.

The continuously conveyed cutouts then pass onto the stack formed on a stacking table 10 (see also Figure 2) whose height is adjustable. They are delivered against a stop 11. Opposite the stop 11 lies a plate 12 which performs an oscillating movement to bring the cutouts into accurately aligned contact against the stop 11. Lateral stops, including an adjustable stop 13 shown in Figure 3, are also provided. The distance between the stops is adjustable to the size of cutouts conveyed in each particular instance. When a predetermined number of cutouts has been stacked, the stacking table 10 has reached a lower level, in which its upper face is in the same plane as the upper face of the transfer table 14. A pusher 15 then pushes the counted and stacked bundles of cutouts 16 formed on the stacking table 10 at the bottom of the stack in the direction of the arrow 1, onto the transfer table 14. Transferring one bundle 16 moves forwards, one width at a time, the other bundles previously transferred onto the transfer table 14.

The bundles 16 are held aligned by means of a guide bar 17 extending parallel to and above the transfer table 14. They thus arrive at a tying unit 18, which is adjustably slideable in the direction of the arrow 19 (Figure 1). The tying unit has a worktable 20 which is disposed at a distance from the end of the transfer table 14. Between the tables 14 and 20 a gap 21 is thus formed through which the typing unit 18 can tie a suitable band around the bundle 16 being tied, which is situated approximately centrally above this gap. Although not shown in the drawings a second guide bar, spaced from the guide bar 17, extends parallel to and above the worktable 20.

To allow each bundle 16 to be tied about its middle point, the tying unit 18 is slideable and adjustable in the direction of the arrow 19. In order to permit this adjustment of length the transfer table is of telescopic construction. In the tying unit the upper face of each bundle containing the same number of cutouts lies at a constant height under the second guide bar. The bundles are under suitable pressure from the vertically adjustable guide bar 17, and second guide bar in the tying unit, so that the individual cutouts in the bundle cannot slip.

Contrary to the usual practice, it is expedient for the closure element of the tie to be disposed above the bundles. In addition, the tying unit may be mounted for rotation through 90". Consequently, the bundles can be tied longitudinally or transversely. For this purpose Figure 4 shows an arrangement in which the tying unit 18 is pivotable about a vertical axis 22 into the position shown in broken lines, that is to say in the direction of the arrow 23. For this reason both the transfer table 14 and the guide bar 17 are extended at right angles. A pusher 24 pushes a bundle which is situated in front of it, without pivoting, onto the L-shaped extension 25 of the transfer table 14. The bundle can then be tied in the longitudinal direction after the tying unit 18 has been pivoted accordingly. The extension of the guide bar 17 lying above the table 25 is not shown in Figure 4.

The details of the mode of operation of the movable support in the region of the stack table 10 will be explained more fully below with particular reference to Figures 2 and 3. Two endless driven chains 26 are mounted respectively upstream and downstream with respect to the conveying direction 1 of the stack table 10 and perpendicular to the direction 1. Blocks 27 having pointed front ends are mounted in rows along the chains, each row of such blocks 27 (the length of the row corresponding approximately to the width of a stack 16) being followed by chain links not provided with such blocks, and these links being in turn followed by a similar row provided with blocks, and so on. This is illustrated in Figure 3. The two chains are driven in synchronism by means of a motor 28, a drive shaft 29, and a belt drive 30 together with a gear 31. The row of blocks 27 and the row of chain links not provided with blocks are disposed in the same positions on each of the two chains 26. The chains are driven in the direction of the arrow 32. Figures 2 and 3 show a position of the chains in which a row of blocks is situated in the path of fall of the cutouts, so that the lowermost cutout, previously displaced laterally by means of the pair of rollers 9, and the cutouts subsequently delivered rest on the blocks 27. In the initial position of the chains 26 the foremost block of each row of blocks is situated just in front of the edge of the stack so that the cutout which has been laterally displaced falls onto this pair of blocks. The two chains are then driven very rapidly and in synchronism in the direction of the arrow 32, to the position shown in Figures 2 and 3 so that the stack continues to be formed above the blocks which now support it.

Above the stack is situated a pressing down means, which consists of a driven belt 33 urging the cutouts to the stop 11 in the direction of the arrow 34. The lower run of the belt 33, which engages the top of the stack, is inclined upwardly towards the incoming cutouts, so as to form a mouth to receive them. The belt 33 is driven by means of another belt 25, which in turn is driven by a drive shaft 36.

The mode of operation of the machine described above is as follows. The glued and folded cutouts which will subsequently be formed into boxes when unfolded, are delivered from a folding unit onto the conveyor track 2 in the direction of the arrow 1 and are counted by the photoelectric cell 8. The photoelectric cell 8 transmits pulses to an adjustable addition counter.

When the number of cutouts preset on this counter has been transported through the pair of rollers 9 and the photoelectric cell 8, the counter transmits a reset pulse. This pulse has the effect of causing the pair of rollers 9 to perform a lateral movement.

The next cutout is thereby moved laterally and, in the stack being formed, each lowermost cutout of a new bundle therefore projects laterally.

The stack is built up on the stack table 10, which is adapted to move vertically up and down. As new cutouts are delivered from above, the stack table is moved proportionally downwards. The new cutouts arriving on the stack are guided to the stop 11, which is adjustable to correspond to the size of cutout being processed. The uppermost sheet is pressed down by the pressing down means 33. The presser means also fulfils the function of pre-aligning the cutout. The actual alignment is efected in the usual manner, for which purpose the stacked cutouts are pressed against the stop 11 by the plate 12 performing an oscillating movement.

The lower part of the stack must now be ejected as an aligned, counted bundle. This bundle is separated from the remainder of the stack by the insertion of the blocks 27.

The distance between the chains 26 is slightly greater than the size of the stack, so that the stack can be moved downwards unhindered between the chains. When the stacking table is lowered together with the stack, the predetermined laterally projecting cutout is supported in each case on the first block of each row of blocks on the chains 26. The stacking table is moved somewhat lower, so that a space is formed between the projecting cutout and the stack moving downwards. The cutouts are of suitable rigidity to permit this, but some flexibility is not excluded. The chains now start to move and thus insert the blocks pointed ends first, into the space. In order to ensure that the blocks will not pull any of the cutouts in the direction in which they move, lateral control stops 13 are provided on the opposite side of the stack. After the blocks have been wound in, the upper part of the stack rests entirely on the blocks, while the lower part is separated for ejection. The pusher 15 pushes the bundle out in direction 1 onto transfer table 14 adjacent the stack table, and then immediately returns to its starting position. The stack table rises again to a height corresponding to the height of the bundle released, and the chains move on a length corresponding to the length of a row of blocks. Because of the previously mentioned stops 13 the upper part of the stack is stripped off the blocks and slides onto the stack table. The next cycle can then commence.

The transfer table 14 preferably has an upper face consisting of a smooth metal sheet. The further treatment of the ejected bundle has already been explained above.

The tying unit 18 of of conventional kind, and need not be described.

Examples of manufacturers of tying units are the following firms: Ampag GmbH & Co. KG, Postfach 50 11 80, 5000 Cologne 50, Germany.

Legamatic SNC C-O INTECMA, Corso di Porta Vittoria 18, I - 20122 Milan, Italy.

O. Siebeck OHG, Verpackungsmaschinen, Postfach 60, 6930 Ebersbach, Germany.

Signode Austrowaren, Verpackung und Beschriftung, Postfach 16, Johannesgasse 23, A - 1015 Vienna, Austria.

WHAT WE CLAIM IS: 1. A method of continuously stacking sheets into bundles containing a predetermined number of sheets, in which the sheets are delivered in a flow onto a stacking surface so as to form a stack with the sheets one above another and the bundles are removed at the bottom of the stack, wherein each sheet which is to form a bottom sheet of a bundle is delivered to the stack offset from the other sheets so that it rests upon a movable support positioned adjacent the stack, and the movable support is thereafter moved into the stack so as to support the said bottom sheet and sheets stacked upon it while the bundle beneath the said bottom sheet is removed, after which the bottom sheet is deposited on the stacking surface.

2. A method according to claim 1 wherein the stacking surface moves downwardly as the height of the stack increases, and is moved upwardly again after removal of each said bundle.

3. A method according to claim 1 or claim 2 wherein the said bottom sheet is moved laterally to offset with respect to the path of movement of the sheets, as it approaches the stack.

4. A method according to claim 3 wherein the lateral movement of the bottom sheet is caused by one or more rollers.

5. A method according to any one of the preceding claims wherein the sheets are glued cutouts which have been folded flat.

6. A method of stacking sheets into bundles substantially as herein described with reference to Figure 1 or Figures 2 to 3 of the accompanying drawings.

7. Apparatus for continuously stacking sheets into bundles, including a stacking surface, means for delivering the sheets in a flow and depositing them one above another to form a stack on the stacking surface, means for selecting which of the sheets is to form the bottom sheet of a bundle associated with displacement means for causing the sheet selected as such a bottom sheet to be stacked offset from the other sheets, a movable support arranged to be positioned adjacent the stack above the stacking surface so as to be engaged by said offset bottom sheet and adapted to be moved into the stack so as to support the bottom sheet and sheets stacked above it while a bundle is removed from below the bottom sheet.

8. Apparatus according to claim 7 wherein the stacking surface is arranged to move downwardly as the height of the stack increases, and to return to an initial position after a bundle is removed from it.

9. Apparatus according to claim 7 or claim8 wherein the said movable support is constituted by a plurality of support members carried by one or more endless elongate elements which are moved, under control, past the stack.

10. Apparatus acording to claim 9 wherein there is a pair of parallel endless driven chains each carrying a plurality of blocks constituting the said movable support, the blocks projecting into the stack as the chain moves past the stack in a direction parallel to the direction of offset of the said bottom sheet.

11. Apparatus according to claim 10 wherein each chain has a portion provided

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (15)

**WARNING** start of CLMS field may overlap end of DESC **. suitable rigidity to permit this, but some flexibility is not excluded. The chains now start to move and thus insert the blocks pointed ends first, into the space. In order to ensure that the blocks will not pull any of the cutouts in the direction in which they move, lateral control stops 13 are provided on the opposite side of the stack. After the blocks have been wound in, the upper part of the stack rests entirely on the blocks, while the lower part is separated for ejection. The pusher 15 pushes the bundle out in direction 1 onto transfer table 14 adjacent the stack table, and then immediately returns to its starting position. The stack table rises again to a height corresponding to the height of the bundle released, and the chains move on a length corresponding to the length of a row of blocks. Because of the previously mentioned stops 13 the upper part of the stack is stripped off the blocks and slides onto the stack table. The next cycle can then commence. The transfer table 14 preferably has an upper face consisting of a smooth metal sheet. The further treatment of the ejected bundle has already been explained above. The tying unit 18 of of conventional kind, and need not be described. Examples of manufacturers of tying units are the following firms: Ampag GmbH & Co. KG, Postfach 50 11 80, 5000 Cologne 50, Germany. Legamatic SNC C-O INTECMA, Corso di Porta Vittoria 18, I - 20122 Milan, Italy. O. Siebeck OHG, Verpackungsmaschinen, Postfach 60, 6930 Ebersbach, Germany. Signode Austrowaren, Verpackung und Beschriftung, Postfach 16, Johannesgasse 23, A - 1015 Vienna, Austria. WHAT WE CLAIM IS:

1. A method of continuously stacking sheets into bundles containing a predetermined number of sheets, in which the sheets are delivered in a flow onto a stacking surface so as to form a stack with the sheets one above another and the bundles are removed at the bottom of the stack, wherein each sheet which is to form a bottom sheet of a bundle is delivered to the stack offset from the other sheets so that it rests upon a movable support positioned adjacent the stack, and the movable support is thereafter moved into the stack so as to support the said bottom sheet and sheets stacked upon it while the bundle beneath the said bottom sheet is removed, after which the bottom sheet is deposited on the stacking surface.

2. A method according to claim 1 wherein the stacking surface moves downwardly as the height of the stack increases, and is moved upwardly again after removal of each said bundle.

3. A method according to claim 1 or claim 2 wherein the said bottom sheet is moved laterally to offset with respect to the path of movement of the sheets, as it approaches the stack.

4. A method according to claim 3 wherein the lateral movement of the bottom sheet is caused by one or more rollers.

5. A method according to any one of the preceding claims wherein the sheets are glued cutouts which have been folded flat.

6. A method of stacking sheets into bundles substantially as herein described with reference to Figure 1 or Figures 2 to 3 of the accompanying drawings.

7. Apparatus for continuously stacking sheets into bundles, including a stacking surface, means for delivering the sheets in a flow and depositing them one above another to form a stack on the stacking surface, means for selecting which of the sheets is to form the bottom sheet of a bundle associated with displacement means for causing the sheet selected as such a bottom sheet to be stacked offset from the other sheets, a movable support arranged to be positioned adjacent the stack above the stacking surface so as to be engaged by said offset bottom sheet and adapted to be moved into the stack so as to support the bottom sheet and sheets stacked above it while a bundle is removed from below the bottom sheet.

8. Apparatus according to claim 7 wherein the stacking surface is arranged to move downwardly as the height of the stack increases, and to return to an initial position after a bundle is removed from it.

9. Apparatus according to claim 7 or claim8 wherein the said movable support is constituted by a plurality of support members carried by one or more endless elongate elements which are moved, under control, past the stack.

10. Apparatus acording to claim 9 wherein there is a pair of parallel endless driven chains each carrying a plurality of blocks constituting the said movable support, the blocks projecting into the stack as the chain moves past the stack in a direction parallel to the direction of offset of the said bottom sheet.

11. Apparatus according to claim 10 wherein each chain has a portion provided

with said blocks followed by a portion not provided with blocks, both portions being of a length corresponding approximately to the width of the stack.

12. Apparatus according to any one of claims 7 to 11 wherein said displacement means comprises at least two rollers disposed adjacent the delivery point to the stack and arranged with their axes transverse to the path of movement of the sheets, the rollers being displaceable axially to cause offsetting of the said bottom sheet.

13. Apparatus according to any one of claims 7 to 12 having means for pressing down the top of the stack comprising a driven belt which has a run which engages the top of the stack so as to urge the top sheet against a stop while being inclined to the top of the stack so as to provide a gap for the next arriving sheet.

14. Apparatus according to any one of claims 7 to 13 wherein said selecting means includes a counter for the sheets as they approach the stack.

15. Apparatus for stacking sheets into bundles substantially as herein described with reference to and as shown in Figure 1 or Figures 2 to 3 of the accompanying drawings.