Sheet diverter wedge including air discharge ports

Details Sheet diverter wedge including air discharge ports Sheet diverter wedge including air discharge ports

2000-03-14

2001-07-03

Skaggs, H. Grant (Department: 3651)

Sheet feeding or delivering

Delivering

Multiple discharge

C271S303000, C271S193000

Reexamination Certificate

active

06254093

ABSTRACT:

FIELD OF THE INVENTION
The invention relates to a sheet diverter wedge for a pinless folder. In particular, the invention relates to a sheet diverter wedge having a plurality of air discharge ports that discharge pressurized air and exert desirable forces on signatures as they are diverted.
BACKGROUND OF THE INVENTION
In the printing industry, a desired image is repeatedly printed on a continuous web or substrate such as paper. The ink is dried by running the web through curing ovens. In a typical printing process, the web is subsequently slit (in the longitudinal direction which is the direction of web movement) to produce a plurality of continuous ribbons. The ribbons are aligned one on top of the other, folded longitudinally, and then cut laterally to produce a plurality of multi-paged, approximately page-length web segments, termed “signatures”. A signature can also be one printed sheet of paper that has or has not been folded. It is often desirable to transport successive signatures in different directions. In general, a sheet diverter operates to route a signature along a desired one of a plurality of paths.
U.S. Pat. No. 4,373,713 discloses a pair of rotary diverters (
62
,
63
) having cam surfaces which divert successive signatures alternately to opposite sides of a diverter wedge (
23
). After passing the wedge, the signatures are engaged by a belt system, comprising inner belts (
25
,
26
) and outer belts (
12
,
13
), that transport the signatures to the next operation.
Similarly, U.S. Pat. No. 4,729,282 discloses a sheet diverter including an oscillating diverter guide member that directs successive signatures to opposite sides of a diverter wedge.
A sheet diverter in a folder at the end of a printing press line must be operable at the high speeds of the press line, typically in excess of 2,000 feet per minute (fpm). It is desirable to run both the press and folder at the highest speed possible in order to produce as many printed products as possible in a given amount of time. However, the physical qualities of paper or similar flexible substrates moving at a too high rate of speed often results in whipping, dog-earring, tearing, or bunching of the substrate. For example, the sudden impact force between the leading edge of a signature and the diverter wedge may result in the leading edge of the signature being damaged. Similarly, the trailing edge of a signature may slap against the top vertex edge of the diverter wedge, resulting in damage to the trailing edge. The trailing edge of the signature may tear, or be unintentionally folded on the corners. Damaged signatures may be of unacceptable quality and may also lead to jams in the folder, resulting in downtime and repair expense.
Additionally, the ink on a printed signature can be smeared, smudged, or offset to the wedge when the signature strikes the diverter wedge at a high rate of speed. Ink offset on the diverter wedge can also cause undesired smudges on successive signatures.
Many of these defects become more prevalent above certain speeds of the printing press and folder. For example, such defects may occur when the press is run at 2300 fpm, but may not occur when the press is run at 2200 fpm.
SUMMARY OF THE INVENTION
It is an object of the invention to provide an apparatus that minimizes the potential for damage to the signatures in a folder.
A principal advantage of the invention is the minimization of damage to the leading and trailing edges of a signature diverted through a folder, while allowing the printing press and the folder to operate at higher rates of speed.
Another advantage of the invention is the minimization of ink offset to the diverter wedge, while allowing the printing press and the folder to operate at higher rates of speed.
The invention provides a diverter wedge for a pinless folder, wherein the diverter wedge is adapted for cooperative association with a diverter guide mechanism operating to direct the lateral disposition of a leading edge of a signature relative to the wedge to one of a plurality of collation paths. The diverter wedge includes an elongated bar having a longitudinal axis and a generally triangular cross section transverse to the longitudinal axis. The bar is fixed in position and includes a base, a vertex edge opposite the base, and planar diversion surfaces diverging from the vertex edge. The wedge also includes at least one air inlet port connectable to a source of pressurized air and a plurality of air discharge ports connected to the air inlet port and intersecting the planar diversion surfaces. In one embodiment, at least one air discharge port intersects the vertex edge.
In another aspect, the invention provides a sheet diverter for diverting a signature to one of a plurality of collation paths and adapted for cooperative association with a cutting device in a pinless folder wherein a web is cut into a plurality of individual signatures. The sheet diverter includes a diverter guide mechanism for directing the lateral disposition of the leading edge of a signature to one of the plurality of collation paths. The sheet diverter further includes a diverter wedge separating the plurality of collation paths. The diverter wedge includes a generally triangular body having planar diversion surfaces diverging from a vertex edge, an air inlet port connectable to a source of pressurized air, and a plurality of air discharge ports connected to the air inlet port and intersecting the planar diversion surfaces. The sheet diverter also includes signature control means downstream of the wedge vertex including a nip defined by rollers and tapes, wherein the nip is offset from the plane defined by one of the planar diversion surfaces, and wherein pressurized air through the air discharge ports directs the leading edge of the signature to this nip.
Other features and advantages of the invention will become apparent to those skilled in the art upon review of the following detailed description, claims and drawings.


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