Sheet feeding or delivering – Delivering – With transfer means between conveyor and receiver
Patent
1991-07-30
1993-11-30
Olszewski, Robert P.
Sheet feeding or delivering
Delivering
With transfer means between conveyor and receiver
271203, B65H 2968
Patent
active
052658619
DESCRIPTION:
BRIEF SUMMARY
CROSS REFERENCE TO RELATED APPLICATION
This application is a National Phase of PCT/EP90/02143 filed Dec. 11, 1990 and based, in turn, upon German National Application P 39 40 960.0 filed Dec. 12, 1989 under the International Convention.
FIELD OF THE INVENTION
The present invention relates to a method for slowing down sheets to be laid on a stack, particularly paper or cardboard sheets, and to a device to implement the method. More particularly, the invention relates to a method of braking sheets, particularly paper or cardboard sheets, to be placed on a stack, whereby the sheets transported at a distance from each other on belts in an feeding plane are slowed down by elements engaging in the area of the rear edge of the sheets.
BACKGROUND OF THE INVENTION
In crosscutting machines which, by crosscutting a web of material, particularly a paper or cardboard web, produce individual sheets to be subsequently deposited on a stack and which operate at high speeds, it is required to slow down the these sheets transported by belts to the stacking location, prior to stacking, in order to insure that the stacking of the sheets is undisturbed.
From DE-B 20 00 078 a generic method is known, according to which the sheets are guided over a fixed suction chamber provided with holes which in a timed manner slows down the trailing edges of the sheets by suction. Subsequently, the sheets are transported to the stacking location by belts running at a speed appropriate for stacking. Since the following sheet runs at first without being braked, its leading edge slides over the trailing edge of the braked sheet, so that the sheets overlap in a scale pattern and are this way transported further. Since the suction acts in each case only upon the lowermost sheet, in multilayered operations wherein for instance eight webs are simultaneously subjected to crosscutting, it is required to provide additional braking for the pack of sheets. This is done by means of a slower running belt portion inclined with respect to the transport plane, against which the leading edge of the sheets of a pack will push.
The known braking devices are expensive structures. It is also possible that, in the case of particularly sensitive papers, marking can occur due to the relative speed with respect to the braking elements. Furthermore, at high operational speeds, sheet jamming may occur.
OBJECTS OF THE INVENTION
It is the object of the invention to provide an improved method and device allowing an increased operational speed with reduced strain on the sheets.
SUMMARY OF THE INVENTION
This object is attained in that in order to be slowed down the sheets are clamped between clamping elements with synchronously and endlessly running clamping zones, which during their revolution temporarily adhere to the sheets.
At the moment of contact with the sheets the clamping zones run at the feeding speed of sheets, subsequently the speed of the clamping zones is slowly reduced to the desired outgoing speed of the sheets, to that the frictional lock with the sheets is maintained, the clamping of the sheets is then released, the clamping zones are removed from the feeding plane prior to the incoming of the next sheet, and the clamping zones are again accelerated to the feeding speed prior to clamping the following sheets. The device for implementing the method has braking sheets displaced along a transport path, the improvement wherein on both sides of the transport path of the sheets synchronously drivable clamping elements with endlessly running clamping zones are provided, whereby the clamping zones of at least one side reach temporarily into the feeding plane during their revolution, so that a sheet can be clamped between two clamping zones. A variable drive is provided for the clamping elements.
According to the invention, the braking force is applied to the sheets without slippage under precisely defined conditions, so that kinematically reproducible conditions exist and no marking can occur. Furthermore, functional and constructional units can be dis
REFERENCES:
patent: 2152288 (1939-03-01), Seybold
patent: 3827545 (1974-08-01), Buhayar
patent: 4461467 (1984-07-01), Herb
patent: 4516759 (1985-05-01), Kobler
patent: 4995859 (1991-02-01), Totani
Becker Ingo
Most Egbert
Naudascher Peter
Schaffner Georg
Welp Ewald G.
Dubno Herbert
Jagenberg Aktiengesellschaft
Milef Boris
Olszewski Robert P.
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