Sheet feeding or delivering – Delivering – By endless conveyor
Reexamination Certificate
1999-04-12
2001-05-22
Skaggs, H. Grant (Department: 3651)
Sheet feeding or delivering
Delivering
By endless conveyor
C271S200000, C271S218000, C414S789900, C414S790800
Reexamination Certificate
active
06234473
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
This invention relates to sheet stackers such as U.S. Pat. No. 3,321,202 granted to M. D. Martin on May 23, 1967 and U.S. Pat. No. 3,419,266 granted to M. D. Martin on Dec. 31, 1968. Specifically, the foregoing sheet stackers handled corrugated and paper board sheets used in making boxes.
The Martin U.S. Pat. No. 3,41 9,266 sheet stacker was provided with an accumulator device which caught the trailing edge and two lead corners of the sheets as they fell from the downstream end of the conveyor. Sheets having die cuts which did not form rigid corners presented problems in accumulating sheets. Long sheets with such weak corners which exceeded the extension capacity of the cross bar holding the trailing edge of the sheet and a portion of the midportion of the sheet could not be accommodated.
Sheets having die cuts which cause flaps or tabs to hang downwardly as the sheet exits the downstream end of the conveyor are sometimes bumped by the leading edge of the rapidly extending cross bar of the Martin U.S. Pat. No. 3,41 9,266 accumulator causing the sheet to be skewed and preventing a straight stack from being formed. Such jams in the stacker require stopping the production line which not only causes a delay but more serious problems result if a box printer or a die cutter is in the upstream production line. Such stoppages can require throwing away partially cut or printed sheets before the production line can be restarted.
In those production lines where the sheets are shingled; i.e. overlapped on the conveyor and are discharged in a continuous stream from the discharge end of the conveyor without gaps or interruptions between sheets, the problem of extending a cross bar or fingers into this stream of sheets at a selected point so as to maintain an accurate count of sheets in a particular stack is not only difficult because the leading edge of the fingers strike the sheets and skew them, but the problem is exacerbated by the flaps and tabs which hang down below the plane of the sheet member.
SUMMARY OF THE INVENTION
The present invention addresses the foregoing problems by fundamentally changing the apparatus used to insert a platform between the sheets falling from the downstream end of a conveyor and then to firmly support the accumulating sheets. Moreover, the apparatus of the present invention also fundamentally changes the way in which the stack of accumulated sheets are discharged onto a load receiving device such as a pallet or conveyor.
The present invention presents a significant improvement in the ability to stack sheets; especially those sheets which have die cuts which result in flaps and tabs which bend downwardly as the sheet free falls from the downstream end of a conveyor onto an accumulator platform.
In general, the present invention discloses a curtain type apparatus which provides a platform in which the portion of the platform in contact with the carried sheet does not move relative to the sheet while it is extending, during holding, or during retraction of the platform.
An object of the present invention is to provide a device which can insert a platform between selected sheets being discharged from a conveyor in either a sequential or a shingled uninterrupted stream without slowing, stopping or interrupting the feed to the conveyor or the stream of sheets while on the conveyor.
An object of the present invention is to catch, hold and release a plurality of sheets while minimizing movement of the sheet from a selected path onto a stack.
A further object is to provide a device which can stack sheets which have been die cut to an extent that present accumulator devices cannot stack such sheets without excessive downtime.
A still further object is to provide a device which can stack sheets much larger in area than can presently be processed in present machines.
Still another object is to provide a machine which can build stacks closer longitudinally to a previously constructed stack than is possible with present machines.
A still further object is to provide a stacker which can operate more reliably, more accurately, and with less down time than present stackers.
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Beckwith Lynn T.
Matlock George L.
Morgan Robert A.
Cypher Charles R.
Cypher James R.
Martin Family Trust
Skaggs H. Grant
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