Material or article handling – Apparatus for moving intersupporting articles into – within,... – Stack forming apparatus
Reexamination Certificate
2002-11-14
2004-08-31
Crawford, Gene O. (Department: 3651)
Material or article handling
Apparatus for moving intersupporting articles into, within,...
Stack forming apparatus
C414S788400, C414S788900, C414S790300
Reexamination Certificate
active
06783317
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention relates to forming a plurality of flat, stiff articles such as flat-folded boxes flowing as a stream of overlapping shingled flat articles, into a stack, more particularly to a method and a device for automatically doing so as well as a device for counting the number of flat articles formed into the stack.
BACKGROUND OF THE INVENTION
In the production of corrugated boxes, corrugated board produced at a corrugated machine is cut and converted into blanks of a desired shape, which are then may be printed or surface finished in some other way. Thereafter, the blanks are flat-folded and glued to form boxes, in a machine commonly known as a folder-gluer machine.
At the outlet of a folder-gluer machine, individual flat-folded and glued boxes are stacked in an overlapping shingled relationship, either in under-stacking or in top-stacking. Under-stacking means that there is a preceding box and a subsequent box, each with a leading edge and a trailing edge (seen in the direction of movement on a moving mechanism such as a conveyor belt), the preceding box being deposited on the moving mechanism before the subsequent box, and whereby the leading edge of the subsequent box is deposited on said moving mechanism under the trailing edge of said preceding box. Top-stacking means that there is a preceding box and a subsequent box, each with a leading edge and a trailing edge again, the preceding box being deposited on the moving mechanism before the subsequent box, whereby the leading edge of the subsequent box is deposited on the moving mechanism on top of the trailing edge of the preceding box.
This shingled flow is moved on between drying pressing belts to be pressed together well and to give sufficient glue drying time, in order to prevent unfolding of the boxes before their glue sets. After leaving the drying pressing belt, generally controlled packets, comprising one or more stacks made in a packeting machine from this flow of shingled individual boxes, are supplied to a strapping machine or strapping section, in order finally to be stacked neatly by a palletising station.
To achieve stable stacking on a pallet, the individual packets should have the same dimension and all opposing sides of the packets must be parallel with each other. Therefore the packeting machine should always make a stack having the same number of individual flat-folded boxes, should align these and where applicable compensate for any angled sides by placing another stack rotated through 180° or another suitable angle (e.g. 90°) on the top, thus forming a packet. This block-like packet is then offered in a way ready positioned for the strapping machine.
In recent years suppliers of machines for handling corrugated cardboard have made significant innovations, especially in the field of folder-gluer machines, which have become considerably faster and more flexible in formats and types of boxes they can handle. The set-up time of such machines has become low and thus also allows profitability in small series. As always, the weakest link in the chain determines the profitability, and this weakest link is at present the packeting machine or packer installation which is still labour-intensive, and restricted in processing of box formats and types. Apparently, development of the subsequent machines (such as e.g. the packeting machine) has lagged behind despite the fact that investment already made for the folder-gluer machines would normally justify further optimisation of the line. These needs have led some machine manufacturers trying to fulfil demand. Unfortunately, known designs do not meet the range of products and format differences, the requirements due to the existing short set-up time, the restricted installation space and, last but not least, the price.
By increasing the production speed of the folder-gluer machines (to more than 15,000 boxes per hour), an extremely dynamic system is required for the packeting machine, to the extent that now the outer limit of present servo-technology is reached. The flexibility in product dimensions and forms further increases the degree of difficulty of forming packets from a continuously supplied stream of flat-folded boxes. The fact that under-stacking is now used more and more, and that the new folder-gluer machines allow this, means that a special approach is required for forming stacks out of the shingled flow, without neglecting the more traditional form of stacking, known as top-stacking.
Different mechanisms already used to separate individual flat-folded boxes to form a stack have been investigated:
1. Individual acceleration of boxes, which are then pushed under each other to form a stack, or which are dropped on top of each other, thus forming a stack.
2. Acceleration at the lower edge of some of the shingled boxes, which together will form a stack, and dropping them on top of each other one at a time in a catchment tray at a lower level.
3. Insertion of a separation finger in a stack where separation must occur and forward movement of a bridge, where the packet is located straight against an upright stop plate. An example of this has been described e.g. in U.S. Pat. No. 5,493,104.
4. Both accelerating the lower edge and the top edge of shingled boxes, and allowing the boxes to fall into a catchment tray below.
5. Obliquely stacked boxes are raised and allowed to fall individually into a catchment tray where they can fall further as a stack after being counted.
All of these solutions present the disadvantage that either the flat-folded boxes must be presented to the packeting machine on a one by one basis, or the continuous shingled flow has to be stopped, which solutions both slow down the handling.
Furthermore, corrugated cardboard boxes are not always rectangular in structure in a flat-folded state (e.g. locking bottom) and/or are not always glued symmetrically (e.g. an automatic-bottom box has, in flat-folded form, five thicknesses of cardboard where the bottom of the box lies, while it has only two thicknesses of cardboard where the top of the box lies). As a result, a number of boxes pushed onto each other in the same direction, forms a stack with the top side misaligned. Hence, when the boxes are stacked for handling or storage, the stack that is formed will have a tendency to topple if all packs of boxes are stacked in the same direction. To make such a stack into a block, it is known to rotate a second stack through 180° in the vertical or horizontal plane. This is called compensation. Depending on the product form, the packet thus formed is more or less unstable (due to accordion movement).
To compensate for the stacks and eliminate misalignment due to oblique sides, various mechanisms are known.
1. A stack of boxes is manually rotated over 180° and placed on top of a stack of boxes previously formed.
2. The boxes fall on a catchment plate and form a stack. This plate is fitted longitudinally in the centre of a drum, the stack stays still and the drum rotates through 180° about its longitudinal axis so that the lower edge of the catchment plate is now on the top. The following stack-forming series of boxes falls onto this. A pusher on the side edge presses the two stacks out of the drum simultaneously so that they fall onto each other and together form a compensated packet.
3. A type of carousel turns in the horizontal plane (like a merry-go-round). On four sides (2 by 2 opposite each other) arms are attached on the outside. On these arms is mounted a finger system, between which a stack can be clamped. The stack is held firmly on two opposing sides by the finger system. The held stack can be rotated about its horizontal axis through 180°. The carousel always turns 90° further on each cycle, after two cycles the stack is again deposited and left. In this way unturned and turned stacks are placed on each other, thus forming a compensated packet.
4. A type of carousel turns in the vertical plane (like a windmill). On four sides (2 by 2 opposite each other) are attached arms at the outside. Attached to t
Barnes & Thornburg
Crawford Gene O.
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