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US 7,296,792 B2Granted
Self-valving vacuum distribution for a belt-driven sheet conveyor
AssigneeMarquip, Inc.
InventorsJohn J. Kondratuk, Carl R. Marschke
Life of this patent
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Abstract
A self-valving vacuum distribution system for a belt-driven sheet conveyor utilizes the sheets to automatically open vacuum control valves sequentially in a downstream direction as the sheet is carried on the belts. The system also automatically adjusts for varying sheet widths to automatically apply vacuum holding force only to the belt conveyor area covered by the sheet.
Claims9
A sheet-actuated vacuum assisted sheet conveyor for the continuous transfer of sheets delivered in serial spaced relation, said conveyor comprising:
- a pair of laterally spaced, parallel driven flat coplanar conveyor belts operating over a flat surface of a vacuum plenum, the flat plenum surface between the belts recessed from the coplanar flat belts to define a shallow vacuum channel;
- a plurality of vacuum control valves in said flat surface spaced in a direction of conveyor belt movement and providing vacuum communication between the plenum and the vacuum channel;
- said control valves operative to be held closed in the absence of a sheet on the conveyor, by a negative pressure in the plenum sufficient to create a first pressure differential across the valves, said valves including means for biasing the valves to open for vacuum communication at a second pressure differential across the valves less than the first pressure differential;
- means for moving sheets into planar contact with the conveyor belts in a manner that progressively covers said vacuum channel;
- and,
- means for applying plenum vacuum to an upstream end of the vacuum channel upstream of the upstreammost valve such that, as a sheet moves to progressively cover said vacuum channel, vacuum pressure in the channel moves in a downstream direction with the sheet to cause the first pressure differential across each valve in succession to decrease to said second pressure differential and said valves to serially open, thereby applying the plenum vacuum directly to the sheet to hold the same against and to move with the conveyor belts.
3 more elements
A self-valving vacuum distribution system for a belt-driven sheet transfer apparatus comprising:
- a vacuum plenum having a flat surface over which a pair of spaced conveyor belts operate to define an open vacuum channel;
- and,
- vacuum control valves spaced along the channel in the flat plenum surface, said valves held closed by a high pressure differential between the vacuum plenum and the open vacuum channel and biased to open under a reduced pressure differential between the vacuum plenum and the vacuum channel, the reduced pressure differential provided by a plenum vacuum connection, including a vacuum starter opening in the plenum surface upstream of the control valves providing initial vacuum communication between the plenum and the upstream end of the vacuum channel when the channel is covered by a sheet carried over the channel on the conveyor belts, the open vacuum channel permitting the plenum vacuum to move downstream as the channel is covered;
- an infeed device adapted to move a line of spaced sheets in series into contact with the conveyor belts and to cause a leading edge of each sheet to override the vacuum starter opening and each control valve in succession;
- each of said control valves including a flat resilient metal plate operatively connected by an edge to the plenum flat surface, said plate having a closure face bent away at an acute angle from the plane of the flat surface to provide the bias to open at said reduced pressure differential;
- and,
- a vacuum opening in the plenum flat surface providing vacuum communication between the plenum and the vacuum channel, said vacuum opening aligned with the valve plate and closed thereby at said high pressure differential.
4 more elements
Dependencies are inferred from the claim text.