Industrial Automation Automation Industrielle Industrielle Automation

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Industrial AutomationAutomation
IndustrielleIndustrielle Automation

• Automation of newspaper printing machines visit
  at CIEL

Prof. Dr. H. Kirrmann
ABB Research Center, Baden, Switzerland
2006 April, HK, 1/36
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Offset printing
The most common form of printing low and
high-volume jobs used today is "offset" - used
for everything from fliers to magazines and
newspapers.
Offset printing uses an intermediate medium
between the printing plate and the paper - the
rubber-coated "blanket" is inked by the plate
roller under relatively low pressure, to prevent
the image from deforming. Half a revolution later
the same image is printed on sheet or continuous
(web) paper under much higher pressures. The
plate is continually inked to maintain the image
on the blanket. Printing plates don't have any
"relief" - there is no change in depth where the
image isn't printed - instead the plate uses
Teflon to repel water from some areas.
http//www.umax.co.uk/support/binuscan/technotes/n
bi03.htm
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Offset plates
The printing plate is initially coated with a
light-sensitive material that protects the
water-repellent Teflon layer below - this top
layer retains water, preventing ink from building
up and being printed on the blanket. In areas
where the Teflon has been revealed water will not
stay on the surface of the plate, but ink will -
hence the exposed areas are those that 'print'.
The coating of the plate is removed using a
photographic process and (typically) a negative
copy of the image-setter films. To produce the
plate, films are held in place over the coating
(usually via a vacuum frame to ensure perfect
contact) while areas of the plate are exposed by
a high-intensity UV light source. The plate is
then chemically processed to expose the Teflon
and fix the coating.
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Halftones - Dot Shape, Screen Ruling and Screen
Angles
To give the illusion of a continuous tone image
when printed, all images have to be recreated
using "halftone" patterns of regularly spaced ink
dots, of varying sizes.
The size of these dots, measured in a percentage
tint, represents the lightness/darkness of each
small area of the image. The spacing of the dots
is the "screen ruling", normally measured in
Lines per Inch (lpi).
To "fool" the eye into seeing a continuous tone
image, the lines of dots are very close together
typical line screen rulings are 133 lpi for mono
(sometimes 120 lpi) or 150 lpi for colour (or
higher). Although these general values are valid
for "conventional" printing, uncoated stocks and
especially newsprint dramatically reduce the line
screens used (e.g. 100 lpi mono / 120 lpi colour).
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Colour printing
bande de papier Papierband
web lead
Colours are reproduced by combining four inks
(CMYK)Cyan, Magenta, Yellow, blacK
A page printed in full colour must therefore pass
through four cylinders, in the order CMYK.
printing cylinder
plate cylinder
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Moiré and rastering
Overlaying several halftones produces
interference patterns, called "moiré".
The most effective dot shape in 4-colour printing
is elliptical - this allows overlaid colours to
be "angled" to minimise interference.
The angle between Cyan and Magenta is critical
as interference is obvious Yellow is far less
critical as the colour is so light against white
paper Black will give interference effects but
is usually only reinforcing dark areas of an
image where moiré is obscured. The screen ruling
(measured in lines per inch) varies between
colours to reduce rosette patterns - the four
"irrational screening" angles will usually
average the output LPI, with black typically the
highest ruling, angled at 45º.
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Computer-to-Plate
In Computer-To-Plate (CTP), there are no films
anymore the plates are directly etched by a
powerful laser and treated chemically. The plate
precision is in the order of 0.05 mm, so that the
different colours blend without visible shadows.
The next step will be Computer-to-Cylinder
there will be no more plates, the cylinders will
be directly written by a laser (and erased for
the next production). However, this technology is
not yet mature and the number of copies produced
in one run (before rewriting the cylinder) is
insufficient for a newspaper production.
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Around a cylinder
plate
rubber cylinder (blanket)
ink
water
homogenizer
water faucets
ink supply
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Two cylinders
plate
rubber blanket
rubber blanket
plate
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Cylinder arrangements
each manufacturer has its preferred cylinder
arrangement
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Tower and Folder
bande
draw roller
tensionvalue
web
25 dN/m
turner bar
barres de retournement
upper H
entonnoir
tour d'impression
folder
cylindres
lower H
20 dN/m
folder roller
infed
débiteur
12 dN/m
plieuse
dancer roller
trotteuse
reelstand
bobines
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The folder
The folder folds one or several webs into bundles
("cahiers"). (picture taken while introducing the
paper in the machine)
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Simple and Double production
double production two newspapers per rotation of
the cylinder the same plates are mounted twice
on the cylinder.
simple production one newspaper per rotation of
the cylinder all plates of a cylinder are
different
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3
cylinder (flattened)
10
7
14
3
10
7
5
6
5
6
16
1
3
14
5
12
10
7
1
1
1
1
1
1
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Web path
web colours couleurs des bandes
turner bar barres de retournement
bars
web
folder plieuse
web width largeur de la bande
reelstands, changeurs de bobines
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Paper colour and cylinder arrangement
Every newspaper is different. The web path is
switched after each productionand the paper is
thread in by a carrier system.
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Web tracks (Chemins de papier)
Nearly every production requires a different
threading
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The transporter
The transporter carries the printed newspapers to
the expedition. En route, insets (advertising,
prefabricated parts) can be inserted.
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Drives
The cylinders were formerly connected by a shaft
(Axe, Welle). Today, the shaft is replaced by an
electronic synchronization based on a hard
real-time bus, SERCOS. The precision of the
drives position is about 0.05 mm, i.e. 2.5
microseconds at 20 m/s web speed.
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Section control
A section is a number of towers producing into
exactly one folder (towers can be assigned to
different folders depending on the number of
pages).
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Several sections (folders)
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Example WIFAG machine
U
U
2
1
Mounted in Cubicle SK
RS
Reelstand Control System (WPOS)
Mounted on Reelstand
PM
PressMaster System
Mounted in Cubicle PMR
CC
MPS Control Console (LS)
EP
Event Fault Printer
PD
MPS Prod. Computer Distribution
Integrated in Cubicle MRV
PD
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The console
The console allows to load the machine
configuration save the settings adjust the ink
and water for each page display the state of the
machine display alarms and events support
diagnostics save the settings
Console Leitstand, pupitre
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Console adjusting the colour for each lane
(screw)
a page is divided into lanes, each each
controlled by a "screw that adjusts the ink and
water ("vis d'encrageFarbschraube) in the
console at right, 11 lanes are visible
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Console adjusting the web tension
the web tension defines the print quality, it
varies as the machine warms up and humidity
changes, but shall not lead to paper tear.
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Console Alarms
there are some 1000 different alarms, categorized
by severity. Alarms must be acknowledged.
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Console On-line help
By clicking on ? a help text corresponding to
the actual windows is displayed with Acrobat
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Control Structure of an H
IBS long-distance bus
Work controller
SERCOS -drive
IBS-M
Display
Local bus
BA
DIO
MCU
LBA
check controller
loop
IO
IO
IO
IO
IBS-M
BA
AIO
MCU
LBA
loop
IO
IO
IO
IO
IBS safety bus
functions
local display, local command buttons,
supervision of paper tear, color screws, water
Turmbus
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Networking a printing machine section
to production preparation (Ethernet)
standby
standby
bridge
PM
PM
GW
GW
LS
LS
LS
Pressmasterbus (Ethernet)
Section bus C (AF100)
V-Sercos
V-Sercos
V-Sercos
Towers
IBG
IBG
IBG
V-Sercos
Interbus-S 4G
IBG
IBG
IBG
IBG
Interbus
Interbus
Interbus
H-Sercos
KT94
KT94
KT94
KT94
KT94
KT94
H -PLCs
KT94
KT94
KT94
KT94
KT94
KT94
KT94
KT94
Service-ARCnet
Falz- und
Wendeturm-
AC160
AC160
AC160
AC160
Tower-ARCnet
Turmsteuerung
Turmsteuerung
Turmsteuerung
steuerung
Section bus D
Section bus B
Section bus C
Line bus - AF100
Rollen-
Rollenwechsler-
Sektions-
Sektions-
KT94
MR93
wechslerkoppler I
AC160
koppler A
steuerung
steuerung
Oxydry-Arcnet
Interbus-S
KT94
Reelstands
ODC
Auro
Oxydry
PECOM-ARCnet
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Multiple sections
MPS Production
MPS
MPS Control Console
PM
LS
LS
LS
PM
LS
LS
LS
PM
LS
LS
LS
PM
LS
LS
LS
tower and folder control
B
E
C
D
Section Control
SS3
SS4
SS5
SS2
OP1
Oxydry (washing)
reelstand control
Reelstands
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Speed and hierarchy
response time
MPS production
Messages
Ethernet
consoles
Arcnet
section control
section control
AF100
tower/foldercontrol
tower/foldercontrol
tower/foldercontrol
Interbus-S
cylindres
SERCOS
motors
Process variables
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Organisation of newspaper production
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Production Order
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Roll logistics
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Prepress and Workflow with MPS Cockpit
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WIFAG
Based in Bern, worldwide number 3
WIFAG and ABB pioneered the shaftless press,
which is standard today.
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