Sheet feeding or delivering – Delivering – With transfer means between conveyor and receiver
Reexamination Certificate
1998-06-23
2001-03-06
Ellis, Christopher P. (Department: 3651)
Sheet feeding or delivering
Delivering
With transfer means between conveyor and receiver
C271S216000, C271S217000, C271S195000
Reexamination Certificate
active
06196540
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an apparatus for stacking sheets. More particularly this invention concerns a blow tube used for separating sheets in an apparatus that receives sheets, normally of paper, one at a time and stacks them up on pallets.
BACKGROUND OF THE INVENTION
Paper sheets are produced from a continuous strip whose longitudinal edges are trimmed and that is then transversely cut into a succession of the sheets that are delivered one at a time one immediately after the other to a stacking apparatus of the type described in commonly owned U.S. Pat. No. 5,628,505 of Voss, U.S. Pat. No. 5,672,045 of Schmid, and U.S. Pat. No. 5,681,038 of Kollann. Such a stacking apparatus typically has a vertically displaceable platform on which is supported a pallet. The sheets are delivered by a conveyor to the stacking apparatus to form a stack on the pallet, which is lowered as the stack height increases so that each sheet has only to drop a minimal distance before coming to rest on top of the stack.
Each sheet is gripped upstream of the station between a lower belt or a group of parallel lower belts and a group of upper belts, but of course the lower belt ends at the input side of the station so that the sheets can drop downward. The upper belts normally therefore extend through the station and serve significantly to guide and position the incoming sheets.
In order to ensure clean separation of the sheets from the upper belts it is standard to provide one or more blow tubes. Such systems are described in East German patent 111,870 of Pretzsch, German patent 2,755,160 of Bodewein (U.S. equivalent 4,221,377), German patent document 3,323,052 of Henkenhaf, German patent 4,012,943 of Vits, Swiss patent 637,090 of Bodewein, and European 0,056,924 of Fitzparick. The blow tubes generally are simple tubes extending in the transport direction between the upper belts and formed with downwardly open holes from which respective jets of air are directed at the upper face of the sheets to push them down off the upper belts onto the stack.
As a rule these blow tubes are fairly expensive items to manufacture. They must be carefully shaped and the nozzle holes must be carefully formed. If nozzle fittings are provided to focus the jets, they must be constructed such that the leading edge of the incoming sheet does not catch on them. As a result blow tubes are a significant investment. Furthermore they are difficult to change or replace in the event of a format change in the sheets requiring a shorter or longer tube, so that one is often inclined to use overlong tubes that result in waste of air pressure and premature separation of the sheets from the upper conveyor belts.
OBJECTS OF THE INVENTION
It is therefore an object of the present invention to provide an improved blow tube for a sheet-stacking apparatus.
Another object is the provision of such an improved blow tube for a sheet-stacking apparatus which overcomes the above-given disadvantages, that is which is of simple and inexpensive construction, yet which performs as well as or better than the more expensive prior-art blow tubes.
SUMMARY OF THE INVENTION
A sheet-stacking apparatus has according to the invention a conveyor including a plurality of parallel upper belts extending in a transport direction for delivering a succession of sheets one at a time to a stacking station and a plurality of blow tubes each having a main portion extending in the direction. The main portions are interleaved with the upper belts and are each formed with a plurality of downwardly open holes. Respective tubular rivet bodies set in the holes have heads bearing upward against the respective tube main portions and form downwardly open nozzles. Interiors of the tubes can be pressurized with air to project jets of air downward from the nozzles of the tube main portions.
Such a blow tube can be made extremely easily and cheaply. The tube itself is drilled out and then the holes are each fitted with a standard so-called pop rivet. Such a rivet, which is according to the invention at least 2 mm long and preferably between 5 mm to 7 mm, forms a simple nozzle that directs a focussed jet of air down at the sheet underneath it. The tube can be produced on a simple bending jig and can in fact be made up right at the site easily, and the pop-rivet nozzles can be fitted to it with standard hand tools.
The rivet heads in accordance with the invention are flat and rounded, that is they fit tightly to the outer surface of the tube but have a rounded or so-called button shape so that the incoming sheets will not catch on them.
Each tube according to the invention includes a connecting portion provided on its end with a snap-coupling half. The pressurizing system includes a horizontal manifold with a plurality of snap-coupling halves matable with the respective snap-coupling halves of the connecting portions. Thus the tubes can easily be removed and replaced. In addition the connecting portion is an inverted J-shaped and has a short vertical portion having a lower end provided with the respective snap-coupling half and a long vertical portion having a lower end from which the respective main portion extends horizontally with an inverted U-shaped bight portion joining the two vertical portions.
The stacking apparatus further has a platform in the station adapted to receive the sheets and movable between an upper and a lower position. The blow tubes are above the upper position.
REFERENCES:
patent: 4197621 (1980-04-01), Mair
patent: 4221377 (1980-09-01), Bodewein et al.
patent: 4625956 (1986-12-01), Marass et al.
patent: 4956936 (1990-09-01), Sprung
patent: 5628505 (1997-05-01), Voss
patent: 5672045 (1997-09-01), Schmid
patent: 5681038 (1997-10-01), Kollann
patent: 5693217 (1997-12-01), Erdmannsdoerfer et al.
patent: 0 056 924 (1982-08-01), None
Menzel Jurgen
Schmid Frank
Deuble Mark A.
Dubno Herbert
Ellis Christopher P.
Jagenberg Papiertechnik GmbH
Wilford Andrew
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