Delivery conveyor with control window ventilation and extraction system

An extractor and a ventilation control window are coupled to the housing of a sheet delivery conveyor to extract unwanted heat, moisture, volatile vapors and obnoxious odors from the conveyor housing to eliminate the need for a separate venting system above the sheet delivery stacker. The suction airflow is varied by adjusting the speed of a vacuum source or motor driven fans, or by adjusting a ventilation window. A sheet control ventilation window is covered by a slidable, transparent panel which permits the operator to observe the orientation of the freshly printed sheets as the suction airflow is adjusted to precision. The sheet control window is also covered by a slidable screened panel which prevents introduction of objects into the press. Volatile vapors, moisture laden air and the like are also extracted from laterally opposite sides of the sheet delivery path, thus helping to control air turbulence at the delivery sheet stacker.

FIELD OF THE INVENTION 
This invention relates to apparatus for transferring printed sheets along a 
transfer path between the last printing unit and the sheet delivery 
stacker of a printing press. 
BACKGROUND OF THE INVENTION 
It has been traditional in the art of sheet-fed printing presses to provide 
systems for supporting freshly printed sheets when transferring the sheets 
from one printing unit to another or when handling the sheets as they are 
transferred by a press delivery system from the last printing unit to a 
sheet delivery stacker. A sheet transfer system comprises a support roller 
or cylinder disposed between one or more printing units in the press and 
which functions to receive a freshly printed sheet from one impression 
cylinder and transfer the sheet to the next printing unit for additional 
printing. The press delivery conveyor system usually includes chain driven 
gripper bars which receive the freshly printed sheets from the last 
impression cylinder of the press and deliver the sheets to the press 
delivery stacker. 
Because the inks used with offset printing presses typically remain wet and 
tacky for some time, marking and smearing of the freshly printed ink is a 
concern in all sheet transfer and delivery systems. When transferring a 
sheet between printing units, marking or smearing of the printed side of 
the sheet is often caused by a fluttering motion of the sheet as it 
transfers through a reverse curvilinear path from the impression cylinder 
to the next transfer cylinder. 
Turbulent air movement is caused by a delivery venting system which 
extracts moisture, volatile vapors and odors released from the freshly 
printed and/or coated sheets. Such delivery venting systems typically 
include a hood that is mounted above the delivery sheet stacker through 
which air is drawn up from the vicinity of the press delivery stacker. The 
resulting turbulent air flow in the delivery area of the press often 
causes fluttering motion of the sheets as they are released over the sheet 
delivery stacker. Moreover, after the grippers release, free fall of the 
sheet is retarded by the updraft of the delivery venting hood so that the 
trailing edge portion of a sheet floats momentarily, then contacts the 
next gripper bar assembly, thus resulting in a sheet jam-up in the 
delivery stacker. 
DESCRIPTION OF THE PRIOR ART 
Prior efforts to at least partially counteract the unwanted sheet flutter 
created by the delivery venting systems have employed relatively small 
blow-down fans, typically mounted in an area immediately above the sheet 
stacker and the vacuum slow down wheels. Although these fans are somewhat 
effective at moderate speeds in keeping lightweight sheets flat as they 
enter the sheet stacker, the fans have not been effective in preventing 
fluttering of lightweight sheets, for example at high press speeds above 
12,000 sheets per hour, as they are moved by the sheet delivery conveyor 
system along the transfer path to the stacker. 
Conventional printing presses also may include a dryer, typically mounted 
in the sheet delivery area, for drying the freshly printed sheets as they 
are conveyed along the transfer path toward a sheet stacker. Heat 
generated by such drying systems may be absorbed by a heat sink, typically 
mounted to take the place of or form a part of a sheet pan guide in the 
delivery system. Such conventional heat sinks are usually water cooled or 
air cooled aluminum rib devices. Such heat sink devices are often 
expensive and excessively complex for cooling the press. Such heat sink 
devices do not provide sheet control. 
Sheet control systems have been proposed which include a stationary sheet 
pan guide having a solid surface and mounted adjacent to the path of the 
sheet transfer delivery grippers for supporting the non-printed side of a 
freshly printed sheet as it is pulled by the grippers from the last 
impression cylinder. Typically, an air vacuum pump is arranged such that a 
pressure differential is created between the dry side of the sheet and the 
support surface of the sheet pan guide so that the sheet is drawn into 
engagement with the sheet pan guide as it is pulled by the delivery 
grippers from the last impression cylinder. 
A limitation of the stationary sheet pan guide apparatus is that, since the 
sheet is drawn onto and pulled against a substantially solid support 
surface of the sheet pan guide, the previously printed side of the sheet 
may be scratched and smeared as it is pulled over this surface. 
OBJECTS OF THE INVENTION 
A general object of this invention is to provide a sheet transfer or 
delivery apparatus for a printing press which operates to engage and 
support the non-printed side or dried side of a previously printed sheet 
in an improved manner as it is conveyed from the last printing unit to a 
sheet delivery stacker. 
Another object of the invention is to provide an improved extraction system 
for removing moisture laden air, volatile vapors and odors created by the 
printing and coating operations of the press. 
Yet another object of the present invention is to provide an improved heat 
removal system for extracting excess heat produced by ink drying systems 
of a printing press. 
As will become more apparent hereinafter, the present invention provides a 
new and improved sheet transfer apparatus operable for engaging and 
supporting the non-printed side of a sheet as it is conveyed between the 
last printing unit and a sheet delivery stacker, and which also removes 
unwanted heat, moisture, volatile vapors and odors from the press. 
SUMMARY OF THE INVENTION 
The present invention provides a vacuum sheet transfer apparatus for 
engaging and supporting the non-printed or dried side of a freshly printed 
sheet as it is conveyed along a transfer path from the last printing unit 
to a sheet delivery stacker. 
The apparatus of the present invention also provides an extraction system 
for removing moisture laden air, volatile vapors and odors from the press 
which are produced during sheet printing and coating operations, thereby 
eliminating the need for a conventional delivery venting system. The 
present invention further provides for extracting excess heat produced by 
ink drying systems of a press, so that conventional water cooled heat 
sinks traditionally employed for this function are no longer required. 
In accordance with one important aspect of the invention, a vacuum sheet 
transfer apparatus includes an array of elongated support rollers adapted 
to support and guide the non-printed side of a freshly printed sheet along 
at least a portion of a sheet transfer path. The support rollers are 
mounted on a frame in side-by-side spaced relationship, and extend 
laterally across the transfer path. The frame on which the support rollers 
are mounted also forms a vacuum chamber. The rollers are disposed over the 
vacuum chamber and provide sheet support along the sheet travel path. 
According to another aspect of the invention, the vacuum chamber is coupled 
to an adjustable vacuum source for creating a variable, negative pressure 
differential within the chamber as air is drawn into the chamber through 
the spaces between the support rollers. By this adjustable draw 
arrangement, the non-printed or dried side of a freshly printed sheet 
maybe floated above the rollers in carefully controlled, floating movement 
or drawn into gentle engagement with the rollers which guide and support 
the sheet as it moves along the transfer path. The rollers may be fixed or 
rotatable, and are characterized by low surface area contact, thus 
minimizing marking and scraping. In the preferred embodiment, the rollers 
are mounted for free rotation, which provides minimum frictional drag. 
Still further, the present invention provides an extractor which eliminates 
the need for a separate delivery venting system over the sheet stacker and 
eliminates the need for water cooled heat sink structures used in 
conventional presses for removing heat generated by sheet drying apparatus 
such as infrared dryers. The extractor apparatus includes a unique 
arrangement of a support frame forming a vacuum chamber and which supports 
a plurality of side-by-side sheet support rollers which are adapted to be 
easily removed for cleaning or replacement without disassembly or removal 
of the apparatus from the press. 
Other features and advantages of the present invention will become apparent 
from the following detailed description taken in conjunction with the 
accompanying drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
In the description which follows, like parts are marked throughout the 
specification and drawings with the same reference numerals, respectively. 
The drawing figures are not necessarily drawn to scale and the proportions 
of certain parts may be exaggerated for clarity. 
As illustrated in FIG. 1, a sheet transfer apparatus in accordance with the 
present invention, generally designated by numeral 11, is shown installed 
on a four color sheet fed printing press 12. The press 12 may, for 
example, be of a type manufactured by Heidelberger Druckmaschinen AG of 
Germany under its designation "Heidelberg Speedmaster 102 V (40 inches)". 
The press 12 includes a frame 14 coupled at one end to a sheet feeder 16 
from which sheets 18 are individually and sequentially fed into the press. 
The opposite end of the press 12 is provided with a sheet delivery stacker 
20 in which the freshly printed sheets 18 are collected and stacked. 
Interposed between the sheet feeder 16 and the sheet delivery stacker 20 
are four substantially identical sheet printing units 22, 24, 26 and 28 
which can print different color inks onto the sheets 18 as they are 
transferred through the press 12. 
As illustrated in FIG. 1, each of the printing units 22, 24, 26 and 28 is 
substantially identical and of conventional design, including a sheet 
in-feed cylinder 30, a plate cylinder 32, a blanket cylinder 34 and an 
impression cylinder 36, with each of the first three printing units 22, 
24, and 26 having a transfer cylinder 38 disposed to pull the freshly 
printed sheets from the adjacent impression cylinder and transfer the 
freshly printed sheets to the next printing unit via an intermediate 
transfer drum 40. The last printing unit 28 is shown equipped with a sheet 
delivery conveyor system 42 which operates to transfer the freshly printed 
sheets from the last impression cylinder 36 to the sheet delivery stacker 
20. 
As illustrated in FIGS. 1, 2 and 3, the sheet delivery conveyor system 42, 
which is of substantially conventional design, comprises a pair of endless 
chains 44, FIG. 3, trained about spaced apart sprockets 45 and 46, 
disposed on each side of the press 12. The sprockets 46 are shown 
supported by a drive shaft 48. The endless chains 44 are operable to 
support, at spaced intervals, sheet gripper assemblies 50, one shown in 
FIG. 3, carrying a plurality of conventional sheet gripper devices 52 
which operate to grip the leading edge of a sheet 18 at the last 
impression cylinder 36, and pull the sheet along a transfer travel path 
defined by the path of movement of the chains 44, which travel path is 
herein generally designated by the arrows A in FIGS. 1 through 3. It 
should be noted that in conventional printing presses, the drive shaft 48 
and the sprockets 46 may also support other components of a conventional 
sheet transfer system, such as skeleton wheels, delivery cylinders, and 
the like. 
A conventional infra-red ink drying system 54, FIG. 2, is shown mounted 
above a substantially linear portion of the transfer travel path of the 
delivery conveyor system 42 to help dry the freshly printed sheets as they 
travel between the last printing unit 28 and the sheet delivery stacker 
20. The drying system 54 is disposed adjacent to and between the conveyor 
chains of the transfer apparatus 11 and generates substantial heat to 
effect drying of the inked sheets as they pass along the sheet travel 
path. 
The sheet transfer apparatus 11 is intended to replace a conventional sheet 
delivery pan, not shown, which typically is formed of a piece of flat 
sheet metal. The sheet transfer apparatus 11 is operable to engage and 
support the unprinted side of a freshly printed sheet 18 in such a manner 
as to prevent fluttering of the sheet while also minimizing or eliminating 
scratching and marring of the previously printed side of the sheet. 
Moreover, the sheet transfer apparatus 11 also eliminates the need for a 
conventional delivery venting system above the sheet stacker and heat sink 
devices since it performs the additional functions of removing heat, 
moisture laden air and volatile vapors and odors from the vicinity of the 
delivery stacker 20. 
Referring now to FIGS. 2, 3, 4 and 5, the sheet transfer apparatus 11 is 
further characterized by a generally rectangular pan-shaped frame 58 
defining a vacuum chamber 60, as shown in FIGS. 3 and 4. The chamber 60 is 
basically defined by frame members comprising opposed end walls 64, 
longitudinal side walls 66 and a bottom wall 70 of the frame. As shown in 
FIG. 4, a plurality of openings 68 are provided in the bottom wall 70 at 
spaced intervals between the end walls 64. The openings 68 are in 
communication with respective manifolds 72, see FIG. 3 also, which are in 
communication with the openings 68 and with respective ducts 74 which are 
connected to the suction inlets of suitable vacuum producing sources 76 
(FIG. 1). 
Preferably, the vacuum sources 76 are centrifugal blowers or vacuum pumps, 
each being driven by an electrical induction motor M. Each induction drive 
motor M is electrically connected to a source of electrical power through 
a variable speed controller 71 and a power conductor cable 73. The running 
speed of the induction drive motor M is manually adjustable by the press 
operator to produce a desired airflow rate through the spaces 77 between 
the support rollers 75. The drive motor M is reversible to produce air 
blast operation for accommodating perfecting printing operations, where 
both sides of a sheet are printed during a single pass through the press. 
Operator control of the suction airflow or blast airflow is also manually 
adjustable by opening and closing a vent plate V which is slidably mounted 
over a vent port Q of each inlet duct 74. The position of the vent plate V 
is adjustable for enlarging and reducing the inlet area of the vent port Q 
which increases and reduces the airflow through the air ducts and as the 
by-pass inlet port Q is opened or closed by extending or retracting the 
vent plate V. Although manual control means are illustrated, the system 
can be easily adapted for automatic control, if desired. 
Positive, predictable sheet control is a necessity in the operation of 
modern high speed presses, which can run at speeds of more than 18,000 
sheets per hour while controlling lightweight sheet stock. In conventional 
printing presses, the delivery conveyor is completely enclosed by a 
protective housing which surrounds the chain driven conveyor assembly, and 
no means are provided for monitoring the freshly printed sheets as they 
are transferred along the sheet transfer path. The existence of a sheet 
delivery problem during the operation of conventional delivery conveyors 
is determined only after sheets have been damaged and/or a sheet jam-up 
occurs. When that happens, it is necessary to E-stop (emergency stop) the 
press and open the conveyor housing to clear the sheet jam. Delivery 
defects such as scratched and smeared sheets may not be detected until a 
substantial number of freshly printed sheets have been run. 
The present invention provides a control window arrangement which permits 
the press operator to observe the sheets as they are transported along the 
sheet transfer path, and permits the press operator to immediately adjust 
the suction air flow or air blast flow through the spaces 77 between the 
support roller 75 for establishing a desired orientation of the freshly 
printed sheets relative to the support rollers as the freshly printed 
sheets are pulled along the transfer path. In addition to direct 
observation and real time control of sheet movement, the control window 
provides access to the interior of the delivery conveyor for the purpose 
of removing sheets, debris, spray powder and the like, and for repair 
access. 
Referring again to FIG. 2, one or more sheet control windows W are formed 
in a sidewall panel P of a protective housing H surrounding the chain 
driven conveyor assembly 42. One purpose of the sheet control window W is 
to permit the press operator to observe the freshly printed sheets as they 
are transported along the transfer path. For that purpose, the window 
opening W is covered by a transparent panel G which is preferably a sheet 
of tempered safety glass or plastic. 
Another purpose of the sheet control window W is to admit ambient air and 
to provide operator access to the inside of the delivery conveyor housing 
for clean-up and repair. The transparent panel G is mounted for slidable 
movement along lower and upper channel guides 79, 81, respectively. The 
position of the transparent panel G is adjustable for enlarging and 
reducing the effective air inlet area of the window opening W to permit 
ambient air to be drawn through the window inlet opening, thus providing 
additional operator control of the airflow and helping to relieve air 
turbulence at the delivery stacker. 
The transparent window panels G are easily removed from the press to 
provide access for maintenance and clean-up, for example of loose sheets 
and spray powder. Moreover, an observation window W may be installed 
adjacent the infrared dryer 54 as shown in FIG. 2 to permit the operator 
to visually inspect the infrared lamps. The transparent panel G can be 
removed to provide operator access during repair of the dryer or 
replacement of the infrared lamps. 
Although a transparent window panel G is preferred, other adjustable 
control window arrangements may be used to good advantage. For example, 
the window covering may be implemented in a form of overlapping louver 
slats which are movably coupled to the sidewall panel P for controlling 
the effective air inlet opening area of the sheet control window W, while 
also permitting observation of freshly printed sheets as they move along 
the sheet transfer path. 
Preferably, the sheet control window opening W is also covered by a 
removable safety screen 83 which will admit ambient air into the delivery 
conveyor housing, but will prevent personnel entry. For this purpose, the 
safety screen is coupled to an interlocking safety switch 85 which enables 
the press and the sheet delivery conveyor when the safety screen is in the 
closed and locked position, as illustrated in FIG. 2, but which 
automatically stops the press when the safety screen 83 is moved away from 
the interlocked position. The safety screen 83 is mounted for slidable 
movement along the lower and upper channel guides 79, 81, respectively. 
The mesh openings of the safety screen are small enough to block entry of 
a small object such as a hand tool, and is preferably constructed of 
stainless steel or plastic. 
Referring to FIG. 1 and FIG. 2, the press operator observes the sheets S 
through the sheet control window W as the sheets are pulled along the 
transfer path. By adjusting the running speed of the induction drive motor 
M, and by adjusting the vent plate V and/or the transparent window panel 
G, the operator can manually change the airflow rate through the 
longitudinal spaces 77 between adjacent support rollers 75, and thus 
establish a desired vacuum draw force or air blast force. For example, it 
may be desired to "float" the sheets relative to the support rollers as 
the sheets are pulled along the transfer travel path, for example during a 
perfecting press run in which both sides of the sheet are printed in one 
pass. The operator accomplishes the "floating" travel orientation of the 
sheet by adjusting the speed of the induction drive motor M in the air 
blast mode while observing the sheets as they pass by the sheet control 
window W. 
During non-perfecting printing, when only one side of the sheet is printed 
and/or coated, the induction drive motors M can be operated in the suction 
mode to impose a vacuum draw force on the sheet which is sufficient to 
cause the trailing end of the sheet to be pulled in "kiss" contacting 
engagement against the rollers 75, which stabilizes the trailing end of 
the sheet. The position of the inspection window panel G is adjusted as 
necessary to prevent fluttering movement of the freshly printed sheets. 
Surface contact with the rollers is minimized or eliminated simply by 
adjusting the airflow rate and the resulting vacuum draw force 
(non-perfecting mode) or adjusting the air blast force (perfecting mode). 
This, in turn, prevents scratching or smearing of the underside surface of 
a previously printed sheet, and eliminates frictional drag. The level of 
vacuum draw or air blast needed for a specific sheet travel orientation is 
dependent upon the press speed and the weight of the sheet substrate. 
Preferably, the motor speed control unit 71 is located adjacent the sheet 
control window W, so that appropriate air flow adjustments and sheet 
control can be made as the operator observes the passing sheet. 
As shown in FIG. 6, in particular, the frame 58 is suitably supported on 
respective brackets 59 connected to opposed side frame members 43, for 
example, of the press frame 14. 
As shown in FIGS. 2, 4 and 6, a longitudinal center frame member 69 extends 
between the transverse end walls or frame members 64 and approximately 
midway between the side walls or frame members 66 and is substantially 
coextensive with the side members 66. The side frame members 66 and the 
center frame member 69 cooperate to support respective sets of sheet 
support rollers 75 which are mounted spaced from each other in a 
substantially linear array along the sheet travel path for supporting the 
unprinted side of sheets 18 as they are pulled along the conveyor system 
by the gripper assemblies 50, respectively. 
The rollers 75 are suitably spaced apart in such a way as to provide spaces 
77, FIG. 5, of sufficient width between adjacent rollers to allow air to 
be drawn into the chamber 60 for extraction therefrom through the 
respective manifolds 72. The rollers 75 mounted near and directly over the 
openings 68 may be disposed closer to each other than the rollers near the 
end frame members 64 so that the widths of the spaces 77 are varied to 
equalize the vacuum effect along the frame 58 between the end members 64. 
Preferably, the rollers 75 are mounted for substantially free rotation on 
the frame 58 so as to minimize any tendency for the previously printed 
side of the sheets 18 to rub or scratch on the roller surfaces. Such 
action could result in scratching or marring of the underside surface of 
the sheets which may be printed or coated during a previous pass through 
the press. The rollers 75 are preferably formed of cylindrical steel or 
aluminum stock having a suitable anti-friction surface finish. Preferably, 
the anti-friction surface finish is a coating or layer of fluropolymer 
resin such as polytetrafluoroethylene (PTFE) resin, for example, as sold 
under the trademarks TEFLON and XYLAN, for minimizing frictional contact 
with the sheets. 
The support arrangement for the rollers 75 is illustrated in FIGS. 7 and 8. 
Referring to FIG. 7, the inboard ends of respective coaxially aligned 
rollers 75 are supported on the frame member 69 by suitable stub shafts 
78, as shown by way of example, for rotation about an axis 79 transverse 
to path P. Referring to FIG. 8, the outboard ends of each of the rollers 
75 are supported by respective spindles 80 mounted on the frame members 
66, as shown by way of example. Each spindle 80 has a stub shaft portion 
82 projecting from the side frame member 66 and a cylindrical collar 
portion 84 which is disposed in a suitable counterbore formed in the frame 
member 66 and retained therein by a fastener 88, preferably threadedly 
engaged with the member 66 at 90. The fastener 88 has a socket head 
portion 92 which is engageable with the spindle collar 84 to retain the 
spindle 80 in its working position shown in FIG. 8. 
The distal end of the stub shaft 82 projects into the inner race bore 94 of 
a suitable sealed anti-friction bearing 96 which is preferably press 
fitted into a bore 98 formed in the end of the roller 75. However, the 
distal end of the stub shaft 82 is a free sliding fit in the inner race 
bore 94. A suitable spacer or washer 100 is interposed between the end 
face of the roller 75 and the side frame member 66 to maintain lateral 
spacing of the roller 75. The roller 75 opposite the roller shown in FIG. 
8 and coaxially aligned therewith is also supported by a spindle 80 on the 
other side frame member 66 in an identical manner to that shown. 
Referring further to FIG. 7, the stub shaft 78 has opposed shaft portions 
103 and 104 and a cylindrical collar 105 which is retained in a suitable 
counterbore formed in the center frame member 69, as illustrated. The 
opposed shaft portions 103 and 104 project into the inner race bores of 
respective sealed anti-friction bearing assemblies 106 which are each 
preferably fitted in a bore 108 of the opposite ends of the rollers 75, 
respectively. Suitable spacers 100 are also sleeved over the shafts 103 
and 104 and are interposed between the center frame member 69 and the ends 
of the rollers 75, as shown. 
Thanks to the stub mounting arrangement of the rollers 75, they can be 
easily demounted from the apparatus 11 for cleaning or replacement, if 
required. For example, if a roller 75 is desired to be removed from the 
frame 58, the fastener 88 which retains the associated spindle 80 on the 
side frame member 66 is removed allowing the spindle 80 to be slidably 
removed from the bearing 96 and the frame member 66. With the spacer 100 
also removed from its position between the end face of the roller 75 and 
the frame member 66, the roller 75 may be moved longitudinally a 
sufficient distance to slide the roller off of its supporting stub shaft 
103 or 104 whereby the roller may be cleaned or replaced. The replacement 
roller 75 with bearings 96 and 106 mounted thereon is then suitably 
slipped over the stub shaft 103 or 104 and aligned with the associated 
spindle receiving bore formed in the side frame member 66 whereupon the 
spindle 80 is then replaced and secured in its working position by the 
fastener 88. 
The operation of the sheet transfer apparatus 11 is believed to be 
understandable to those skilled in the art from the foregoing description. 
When the press 12 is being operated to print sheets 18 and the conveyor 
system 42 is transferring the freshly printed sheets from the last 
printing unit 28 to the delivery stacker 20, the vacuum pumps 76 are 
substantially continuously operated to draw air through the spaces between 
the rollers 75 into the chamber 60 and through the openings 68 to the 
manifolds 72 and the inlet ducts 74 leading to the respective vacuum pump 
or vacuum source 76. As printed sheets are traversed along the travel 
path, the pressure differential created by drawing air between the 
respective rollers 75 into the chamber 60 will bring the sheets into 
gentle contact with the rollers to substantially eliminate any fluttering 
or unwanted movement of the sheets. 
At the same time, heat generated by the dryer 54, any dampener moisture on 
the sheets and any volatile vapors released from the inks, or coating 
odors, are also drawn into the vacuum chamber 60 and through the manifolds 
72 to the vacuum pump or vacuum source 76 for suitable discharge or 
treatment away from the press 12. Accordingly, the transfer apparatus 11 
eliminates the requirement for a separate venting system for the delivery 
stacker 20. Moreover, the transfer apparatus eliminates the need for 
separate heat sink devices and provides improved support for the freshly 
printed sheets 18 as they are transferred from the last printing unit to 
the sheet stacker 20. 
Referring briefly to FIGS. 9 and 10, a modification to the transfer 
apparatus 11 is illustrated wherein the frame 58 has, in place of the 
manifolds 72, a plurality of self-contained, electric motor driven ducted 
fans 112 supported on the bottom wall 70 of the frame and disposed over 
the respective openings 68. The fans 112 may be operated as vacuum pumps 
to draw air into the chamber 60 or as blower fans to blast air out of the 
chamber in the same manner that the vacuum pumps 76 and centrifuged 
blowers are operated for accommodating non-perfecting and perfecting press 
operations, respectively. However, in the embodiment of FIGURES 9 and 10, 
air is expelled from the discharge ends 113 of ducts 115 for the fans 112 
back to atmosphere. 
Accordingly, the embodiment shown in FIGS. 9 and 10 is useful in certain 
applications of the sheet transfer apparatus 11 wherein a conventional 
press delivery venting system is already installed, but use of the 
transfer apparatus 11 is still desirable for its benefits in controlling 
sheet orientation and heat removal from the vicinity of the sheet delivery 
conveyor. The modification illustrated in FIGS. 9 and 10 provides the 
pressure differential desired to effect engagement of the sheets 18 with 
the rollers 75 or floating the sheets (for perfecting printing runs) and 
sufficient airflow to draw heat away from the conveyor system 42 in the 
vicinity of the drying system 54. The operation of the modified apparatus 
11 described in conjunction with FIGS. 9 and 10 is also believed to be 
understandable to those skilled in the art from the foregoing description. 
In some printing applications, it is desirable to apply a protective and/or 
decorative coating over all or a portion of the surface of the freshly 
printed sheets. Such coatings typically are formed of a UV-curable or 
water-soluble resin applied as a liquid solution or emulsion by an 
applicator roller over the freshly printed sheets to protect the ink and 
improve the appearance of the sheets. Use of such coatings is particularly 
desirable where decorative or protective finishes are required such as in 
the production of posters, record jackets, brochures, magazines, folding 
cartons and the like. Preferably, the coating operation is performed as an 
in-line coating application, rather than as a separate step after the 
printed sheets have been delivered to the sheet delivery stacker. A 
suitable in-line coating apparatus 120 is disclosed in U.S. Pat. No. 
5,176,077, assigned to the assignee of the present invention, the 
disclosure of which is incorporated herein by reference. 
As shown in FIG. 11, an in-line coater 120 is mounted between the upper and 
lower runs of the conveyor delivery chains and downstream of the delivery 
shaft 48, and positioned so that its applicator roller 122 can be 
frictionally engaged against the delivery cylinder 46. The applicator 
roller 122 applies a liquid coating material to the surface of the freshly 
printed sheets. The liquid coating material contains obnoxious volatiles, 
such as ammonia compounds, which are offensive to press personnel. In 
conventional sheet delivery conveyors, the coating volatiles are conducted 
through the protective conveyor housing H and are discharged into the 
delivery stacker. Consequently, there is a strong concentration of 
offensive, obnoxious volatiles in the press delivery stacker area. 
According to one aspect of the present invention, the obnoxious volatiles, 
odors, moisture and the like are extracted from the sheet delivery 
conveyor housing through extractor manifolds 124, 126 which are coupled to 
opposite sidewall panels 128, 130, respectively, as shown in FIG. 11 and 
FIG. 12. The extractor manifolds 124, 126 are coupled in flow 
communication with sidewall panel extractor ports 134, 136, respectively. 
Obnoxious fumes, odors, moisture and the like are drawn from the interior 
of the sheet delivery conveyor housing H through the extractor ports 134, 
136 and extractor manifolds 124, 126 into exhaust ducts 138, 140, 
respectively. The exhaust ducts 138, 140 are joined by a Tee union 142. 
The Tee union 142 has a common outlet duct 144 which is connected to the 
input of a vacuum source 76, such as a vacuum pump and induction drive 
motor combination as previously discussed. 
By this arrangement, the running speed of the induction drive motor M is 
manually adjustable by the press operator to produce a desired suction 
airflow through the exhaust ducts 138, 140 whereby substantially all of 
the obnoxious volatiles, odors, moisture and the like are removed from the 
conveyor housing. Preferably, the extraction flow rate through the exhaust 
ducts 138,140 are equal for the purpose of maintaining balanced airflow 
conditions across the sheet travel path. By this arrangement, virtually 
all of the offensive, obnoxious gases and vapors are extracted from the 
press before the freshly printed sheets reach the delivery stacker. 
Although alternative embodiments of the invention have been described in 
detail herein, those skilled in the art will further recognize that 
various substitutions and modifications may be made to the embodiments 
illustrated and described without departing from the scope and spirit of 
the invention as set forth in the appended claims.