Sheet feeding or delivering – Feeding – Pack holders
Reexamination Certificate
1999-08-04
2001-09-11
Ellis, Christopher P. (Department: 3651)
Sheet feeding or delivering
Feeding
Pack holders
Reexamination Certificate
active
06286826
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to sheet-fed printing machines and, more particularly to an improved stack changing device for sheet feeders of sheet-fed printing machines.
BACKGROUND OF THE INVENTION
It is a known practice in sheet feeders of sheet printing machines or other sheet processing machines to provide arrangements for automated stack changing. These may consist of rack-type structures, so-called remaining-stack carrying devices, which are provided with pushing and lifting drives for horizontal and vertical movements. Such so-called non-stop stack changers are suited, for example during the printing of paper sheets, i.e. with the machine running, to take over remainders of worked-out sheet stacks from, for example, a pallet provided with grooves and to deposit them again onto a new sheet stack subsequently installed in the sheet feeder. Known devices are distinguished by high construction and assembly expenditures and require special constructions of the sheet feeders. Further, devices are used the remaining-stack carrying device of which has a rack engaging into the grooves of the pallet. This rack is to be removed when the remaining stack is combined with the newly installed sheet stack to form a single whole stack from the two stack parts. This involves high drive forces and puts a very severe strain on the sheets lying closest to the cut point. Furthermore, retaining means are provided which prevent a shifting of the stack parts and in the process a severely strain the stack edges. Furthermore, the operation of the sheet feeder itself is severely hampered or even rendered impossible. The sheet running during the changing process is difficult to control, so that again and again waste sheets result. Devices have been developed already, however, which partly avoid some of the disadvantages described.
Thus from DE 32931710 C2 there is known a non-stop sheet feeder for sheet rotary machines. It has a remaining-stack carrying device which is arranged underneath a conveyor table leading from the sheet feeder to the sheet rotary machine. The remaining-stack carrying device has a closed frame on which there are arranged non-stop bars which are driven as piston rods of individual cylinder by means of a pressure medium and which are drivable into grooves of a pallet carrying a sheet stack. The non-stop rods in the driven-in state lie on both sides of the frame and are removed in succession from the range of the sheet feeder. Nothing is said, about the operating sequence. The control of the non-stop bars is very involved and not directly adaptable to the requirements of the stack changing.
From DE 4203500 Al a sheet feeder is known. It presents, parallel to the sheet feeder and allocated to this on the face side, a remaining-stack carrying device as independent component. Therein, individually drivable pointed bars are provided which are drivable over a common drive into grooves of a pallet carrying a sheet stack. The drive has individual chain drives that are coupleable to the respective pointed bars. For the guidance and accessibility of the chain drives, special constructive measures are required. The chain drives are constantly spanned under a frame of their own and completely block the space in front of the sheet feeder, so that the latter is not accessible. In the stack changing, the pointed bars out of the stack zone can be removed, in the combining of main and remaining stacks, first on the outside, then in the middle and lastly in the zone between the already pulled pointed bars, so that there is supposed to be a gentle depositing of the remaining stack on the sheet stack. For this it is necessary to couple the chain drives in an expensive manner onto the pointed bars, in which operation the drive of the pointed bars can occur only in common.
OBJECTS AND SUMMARY OF THE INVENTION
In view of the foregoing, an object of the present invention is to provide an improved stack changing device which overcomes the problems associated with prior art designs.
A more specific object of the present invention is to provide a stack changing device which allows for simple and continuous stack changing through the use of a drive that is optimally adapted to the desired stack changing conditions.
The present invention provides these and other advantages and overcomes the drawbacks of the prior art by providing a stack changing device with an improved drive for moving the remaining-stack carrying bars.
It is advantageous that remaining-stack bars are provided which are movable independently from one another are provided in the device, and which are drawn, intermittently, out of the stacking zone. The simple and compact drive proposed for this purpose makes possible the space-saving arrangement of the remaining-stack carrying device. A differing height of the remaining-stack bars generates a smooth depositing movement of the remaining stack on the sheet stack. The continuous removal of the remaining-stack bars from the inside, outward and in two stages makes possible a gentle depositing of the remaining stack onto the sheet stack. As the remaining-stack bars are made of differing length, there results an improved working run-off. Further improvements are brought by a staggering of the speed of the individual remaining-stack bars to one another.
These and other features and advantages of the invention will be more readily apparent upon reading the following description of preferred exemplary embodiments of the invention and upon reference to the drawings wherein:
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Basel Uwe
Gebel Jens
Hinz Marc
Hummel Peter
Ortner Robert
Bower Kenneth W.
Ellis Christopher P.
Leydig , Voit & Mayer, Ltd.
MAN Roland Druckmaschinen AG
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