Sheet feeding or delivering – Delivering – To receiver for pack of sheets
Reexamination Certificate
1999-02-24
2001-03-27
Walsh, Donald P. (Department: 3653)
Sheet feeding or delivering
Delivering
To receiver for pack of sheets
C271S213000, C271S214000, C187S363000, C187S359000, C187S361000
Reexamination Certificate
active
06206366
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a sheet-stacking apparatus. More particularly this invention concerns such an apparatus which forms stacks of continuously arriving sheets.
BACKGROUND OF THE INVENTION
In a paper mill a continuous strip of paper moving longitudinally at high speed must be transversely cut into individual sheets that must then be piled in individual stacks on pallets or the like. The stacking must be done without interrupting the flow of continuously arriving sheets, so that when a stack is complete it is necessary to get it out of the way and bring a new pallet into place while somehow catching and holding the sheets that arrive during the changeover.
Commonly owned U.S. Pat. No. 5,628,595 describes an apparatus having a downstream end spaced upstream in a horizontal transport direction from a stacking station for delivering the sheets continuously one after the other at a predetermined upper level in the direction to the station and a main platform vertically displaceable in the stacking station between an upper position below the upper level and a lower position. An auxiliary platform below the upper level is formed by a plurality of parallel rods horizontally displaceable in the direction between an extended position in the station above the main platform and a retracted position upstream of the main platform. A plurality of vertically extending separator elements having bent-over upper ends projecting downstream between the rods in the transport direction are displaceable between a separating position projecting into the station between the auxiliary platform and the upper level and engaged between trailing edges of sheets and a withdrawn position out of the station between the station and the conveyor downstream end. Each element has a vertical length greater than the vertical distance between the auxiliary platform and the upper level.
German patent 2,749,912 issued Nov. 8, 1971 to R. Schmitz shows an arrangement where the sheets are deposited on a platform that is lowered in a frame as the stack formed on the platform grows. The platform is suspended from cables and can, when fully loaded, weigh several tons. It is sometimes moved vertically as much as 3 m. Obviously if, for instance, one of the cables broke and the loaded platform dropped, it could do considerable damage to the apparatus. Accordingly this German patent proposes an antidrop mechanism that arrests the platform by jamming toothed guide wheels into a stationary rack. Such a system is effective but fairly complex.
OBJECTS OF THE INVENTION
It is therefore an object of the present invention to provide an improved sheet-stacking apparatus.
Another object is the provision of such an improved sheet-stacking apparatus which overcomes the above-given disadvantages, that is which has an improved antidrop mechanism.
SUMMARY OF THE INVENTION
An apparatus for stacking sheets has according to the invention a frame defining a stacking station, a conveyor for delivering the sheets continuously one after the other at a predetermined upper level in a transport direction to the station, and a platform vertically displaceable in the stacking station between the upper level and a lower level. The anti-drop protector includes a vertically extending rack fixed on the frame, a lever pivoted on the platform adjacent the rack and having a pair of arms one of which is connected to a lift cable, a stop on the other of the lever arms engageable in the rack, and a spring braced between the platform and the lever. The cable is connected to a drive that tensions the cable, displaces the platform vertically, and rotates the lever in one rotational sense. The spring urges the lever in the opposite sense so that when the cable is detensioned the spring urges the stop into the rack and vertically arrests the platform.
Thus this simple system ensures that, as soon as the cable is detensioned, for instance when the cable breaks or something prevents the platform from dropping, the stop will engage in the rack and prevent further dropping of the platform. The action is simple and foolproof, and the equipment is simple and inexpensive. In addition, unlike the system of the abovecited German patent, there is no significant lateral stress on the rack in the blocking position, so it can withstand considerable forces.
According to the invention the spring is a compression spring braced against the one arm. The lever has a central pivot and the two arms extend at an obtuse angle to each other. Normally the one arm connected to the cable extends horizontally from the pivot and the other arm carrying the stop extends upward at an acute angle to the horizontal from the pivot.
The other arm is provided with an elastomeric bumper carrying the stop so that, when it moves into the movement-blocking position, it does not stop the platform too suddenly.
In addition in accordance with the invention a switch on the platform is operable by the lever on rotation in the opposite sense. This switch can shut down the equipment and/or cause a trouble alarm to be emitted.
REFERENCES:
patent: 710038 (1902-09-01), Burgart
patent: 855646 (1907-06-01), Lehn
patent: 1278742 (1918-09-01), Pichler
patent: 1714297 (1929-05-01), Crispen
patent: 2266915 (1941-12-01), Steedman
patent: 3848706 (1974-11-01), Darwent
patent: 4254939 (1981-03-01), Buzzard et al.
patent: 4725185 (1988-02-01), Neagu
patent: 4745726 (1988-05-01), Rosenthal
patent: 5628505 (1997-05-01), Voss
patent: 183212 (1907-03-01), None
patent: 2512685 (1975-09-01), None
patent: 27 49 912 (1979-11-01), None
patent: 411160 (1910-06-01), None
patent: 23312 (1911-10-01), None
patent: 1429181 (1976-03-01), None
patent: 1668268 (1991-08-01), None
Dubno Herbert
Jagenberg Papiertechnik GmbH
Schlak Daniel K
Walsh Donald P.
Wilford Andrew
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