|
|
The
GALLANTIC1217
CD HIGH SPEED
OFFSET PRINTING
MACHINE employs
the process of
offset lithography
to make reproduction
of a desired image.
Following is a
description of
the process, which
is referenced
to shown figure.
The process begins
when an image
is produced on
a plate, or master,
which is a sheet
of metal or special
type of paper.
The image is made
of a substance
that has an affinity
for grease-containing
material, so that
printer's ink
(greasy) will
tend to be held
more strongly
by the image that
by the blank (non-imaged)
areas of the plate.
|
|
Next,
water is manually
applied to the
surface of the
plate. This
application
renders the
clear (non-image)
area repellent
to ink while
the image is
not materially
affected in
its affinity
for ink. The
process is generally
referred to
as "pre-dampening".
At this point,
the imaged plate
is mounted on
the plate cylinder
of the machine.
Then, the machine
is turned on
and the cylinders
begin to rotate
in the directions
shown by the
arrows in the
figure.
With the rollers
having been
properly inked
and damped beforehand,
the single-lever
control is moved
to the (damping),
position. This
brings the damping
form roller
into contact
with the plate
on the plate
cylinder so
that damping
in the form
of water is
applied to the
entire surface
of the plate.
The application
of water maintains
the condition
initially established
by pre-dampening
procedure.
After the cylinders
have made four
or five revolutions,
the single-lever
control is moved
to the (inking),
position. By
this action
the two ink
form rollers
also are brought
into contact
with the plate,
and the image
becomes inked
while the clear
area remains
free of ink.
The ink adheres
to the image
and is not driven
off by the damping
because the
attractive tendency
of the image
remains stronger
than the repelling
tendency of
water. This
condition is
maintained as
long as ink
and damping
are applied
in the proper
amounts, in
which case they
are said to
be "imbalance".
After ink has
been applied
for three or
four revolutions,
the single-lever
control is move
to the Impression,
position. This
brings the plate
cylinder into
contact with
the rubber blanket
on the blanket
cylinder, with
the result that
a reversed (or
mirror) image
is offset onto
the blanket.
This image is
allowed to build
up for a few
revolutions
of the cylinder
before paper
is fed.
The feeding
of paper begins
when the pump
switch is turned
on with the
machine running.
The vacuum nozzle
picks up the
topmost sheet
and feed in
to the pullout
wheels, and
the pullout
wheels feed
the sheet onto
the conveyer
belts of the
register board.
The belts in
turn carry the
sheet to the
feed rollers.
Which in turn
feed the sheet
to the grippers
of the impression
cylinder.
A mechanism
detects the
sheet and causes
the impression
cylinder to
press the sheet
against the
blanket as the
sheet passes
through in between
the impression
cylinder and
the blanket
cylinder. Consequently,
the already
reversed image
on the blanket
is impressed
upon the sheet
and thereby
reversed again
to become a
right-reading
image (as is
the image on
the plate).
When the leading
edge of the
sheet emerges
from the nip
of the cylinders,
the grippers
open to release
the sheet, at
same time the
sheet is catch
by chain delivery
gripper barÕs
Gripper Tips
& it will
carry the sheet
to the delivery
tray. Their
sheet will align
& set as
stake form.
This process
goes on revolution
after revolution
and sheet after
sheet until
the machine
stops or runs
out of supplies.
The plate is
continuously
damped and inked,
with the flowerets
of both ink
and water so
adjusted that
the water input
is equal to
the water lost
to the plate,
and the ink
input is equal
to the amount
of ink used
by the sheets.
|
