Conveyor for printed sheet material with air assisted drop

A sheet material conveyor includes a pocket conveyor with at least one moving pocket for collecting printed sheet material, the pocket conveyor having a release area for releasing the printing sheet material in the pocket. The sheet material conveyor also includes an air supply device providing air to the pocket at the release area. A pocket with air supply holes and a method for releasing printed sheet material using pressurized air is also provided.

BACKGROUND INFORMATION

The present invention relates generally to the graphic arts industry and more particularly to a conveyor for printed sheet material, as well as to a method for transferring printed sheet material.

After printing by a printing press, printed sheet material may be cut, folded and collected into stacks. Newspaper sections for example may be collected together. The collected sheet material is then transferred and conveyed in various manners. The collected sheet material may be for example collected in individual moving pockets. The collected sheet material may be collected by insertion into open sections, or by collation as separate individual sheets or sections are placed side-by-side, or by both insertion and collation.

An example of a pocket conveyor is for example found in U.S. Pat. No. 6,447,229, which prepares spines for binding, which is hereby incorporated by reference herein. U.S. Pat. Nos. 4,479,643 and 3,874,649 also disclose pocket conveyors. Heidelberger Druckmaschinen AG also manufactures the MAGNAPACK pocket conveyor.

The sheet material, once collected, may be transferred to a further conveyor by opening the bottom of the pocket and permitting the printed sheet material to be dropped. For example, Heidelberger Druckmaschinen AG manufactures a gripper called the NP125 which can grip newspaper sections dropped from a pocket conveyor.

BRIEF SUMMARY OF THE INVENTION

Parts of the collected printed sheet material, when dropped from the pocket, may encounter friction against parts of the pocket and thus fall unevenly or become stuck in the pocket. This can cause problems with spine registration or with further conveying of the printed sheet material. As one example, newspaper sections may be collated in the pocket so that a non-glossy newspaper section is located against the pocket wall, and a glossy newspaper section or insert is located next to the non-glossy newspaper section. When the pocket opens to drop the newspaper, the non-glossy newspaper section may fall more slowly or not at all due to the friction caused by the wall, while the glossy section falls quickly due to the reduced friction of the glossy coating. Spine registration is adversely impacted, and malfunction of the entire device may result.

An object of the present invention is to provide a pocket conveyor providing reduced friction during a drop. An alternate or additional object of the present invention is to provide a pocket conveyor which can improve transfer of printed sheet material.

The present invention provides a sheet material conveyor having a pocket conveyor with at least one moving pocket for collecting printed sheet material, the pocket conveyor having a release area for releasing the printing sheet material in the pocket; and an air supply device providing air to the pocket at the release area.

The pocket may have a pocket foot which is released at the release area to drop the printed sheet material.

The pocket may include an angled collect wall having air holes for the air.

The air supply device may include an air manifold on each pocket connected to the air holes, and may include an air transfer unit for transferring air to the air manifold. The air transfer unit preferably is located at the release area. The air transfer unit, in one embodiment, may include a pressurized air source, a belt having holes interacting with the air manifold on the pocket, and a drive driven by the pocket.

The sheet material conveyor may include a further conveying unit located below the pocket at the release area. The further conveying unit may be a gripper conveying unit and may run at a speed similar to that of the pocket.

The present invention also provides a printed sheet material pocket having a collect wall, the collect wall having a plurality of air holes for providing pressurized air to printed sheet material collected on the collect wall.

The present invention also provides a method for transferring printed sheet material from a pocket conveyor, the method including the steps of providing pressurized air to the printed sheet material, and releasing the printed sheet material from the pocket while the pressurized air is being provided.

The method advantageously may further include first collating printed sheet material having different coefficients of friction in the pocket conveyor.

The method also may further include gripping the printed sheet material after the releasing step.

DETAILED DESCRIPTION

FIG. 1shows a moving pocket10above a gripper conveyor20with grippers28moving along a track22. Pocket10may have a collect wall18, and a foot14. Printed sheet material50is collected, for example by collation, so as to be supported by foot14and so as to rest against collect wall18. Collect wall18is angled with respect to the pocket travel direction and may be moveable or adjustable. Attached to collect wall18is an air manifold16for supplying low pressure air through air holes in collect wall18when the air manifold16is supplied with pressurized air.

As shown inFIG. 5, air holes30may be spaced across the width and height of collect wall18, and the further apart holes in each direction preferably extending at least half the width of the printed material so as to be able to create a substantial air cushion between the wall18and printed sheet material50.

Pocket10, as shown inFIG. 1, may also further include a spring wall12which maintains the printed sheet material against the collect wall18.

As shown inFIG. 2, at a release station, foot14is pivoted to release the sheet material50. Due to the air cushion between collect wall18and sheet material50, the sheet material50may drop together into gripper28. The present invention is particularly advantageous with respect to collated sheet material, as shown. For example, even if sheet material section52has a high coefficient of friction, for example section52is a non-glossy newspaper section, and sheet material section54has a lower coefficient of friction, for example section54is a glossy advertising section, the sections52and54can drop together, since the air cushion between wall18and section52reduces frictional forces to less than that between the sections52and54.

FIG. 3shows a perspective view of the conveyor according to the present invention at the release area. A plurality of pockets10run on track or rails40, pockets10and rails40thus defining a pocket conveyor. A carrier15supports pocket10on rail40and ensures that manifold16lines up with an air transfer unit60. Air transfer unit60includes a pressurized air source66providing pressurized air to an enclosed area behind a belt62. On top and below the belt62may be driven by a toothed belt section64, which may interact with teeth on the carrier15to drive the belt62. Air holes68interact with manifold16as the belt62is driven by pocket10, so that as pocket10passes by the belt62, air is supplied via supply66, through holes68to manifold16to holes30in collect wall18. Air transfer unit60preferably is adjustable so that the air pressure provided through air holes68is adjustable. The actual air pressure desired will depend on the materials used in the pocket and the type and size of the printed sheet materials being collected and may be adjusted by the operator to ensure that the printed sheet materials are properly transferred.

Holes68may be open or have coverings that open when, for example, a protrusion of the manifold16passes into one of the holes68.

Air as defined herein may include any compressible fluid.