IMPROVEMENTS IN PLATE PRINTING MACHINERY
Year: 1877

page_text: PROVISIONAL SPECIFICATION left by Robert Wilmot Wilkinson and
Charles James Wallis at the Office of the Commissioners of Patents on the.
9th June 1877.
ROBERT WILMOT WILKINSON and CHARLES JAMES WALLIS, both of Farringdon
Rond, in the City of London, Engravers and Printers. "IMPROVEMENTS IN PLATE
PRINTING MACHINERY."
This Invention relates to improvements in the plate printing machine which
forms the subject of a Patent granted to one of the present applicants, and bearing.
date July 29th, 1875, No. 2682.
In this machine the engraved plates were carried by tables which were caused
to travel over an annular bed, to present their plates first to an inking roller, .
then to revolving cleaning pads, afterwards to revolving polishing pads, and
lastly to a platten or to impression rollers, as the case might be.
As an improvement on the inking device, we mount the inking roller in
adjustable bearings carried by frames, which are free to rock on the axle of
the ductor roller, and thus allow of the inking roller being raised clear of and
lowered onto the plate, and yet maintaining contact with the ductor roller.
The inking trough is formed between the sides of the main framing, the knife or
scraper constituting one side, and the ductor roller the other side of the trough.
Pivotted to the side framing is a bar which underlies the extended axle of the
inking roller, and is supported at its free end on a rocking arm, its position with
regard thereto being determined by an adjusting screw. On the side of this rocking
arm is a tappet, so situate that as the tables pass beneath the arm to present the
engraved plates to the inking roller, a pin which they carry will strike against this
tappet, lift the arm and the bar resting thereon, and thereby raise the inking
roller to permit of the edge of the plate passing under it. When this is
accomplished the pin on the table will clear the tappet and allow the inking roller
to drop into contact with the plate. As the plate moves forward in contact with
the inking roller, the inking of the plate will be effected. This arrangement
prevents the front edge of the plates from being fouled by coming into contact
with the inking roller.
In order to insure uniformity in the amount of wiping.and polishing received
by the plates, the spindles upon which the pads are carried are made to rise when

page_text: the machine stops, and to fall so as to bring the pads in contact with the
surface of the plates when the machine is put in motion.
This is effected by the following contrivance:-To the belt shifter bar (described in
the Specification of the Patent above referred to) is attached a rod which connects
it with an arm upon a horizontal rocking shaft, suitably supported by bearings on
the main framing. Upon this shaft are two levers (one for the wiping apparatus
and one for the polishing). These levers are counterweighted, and they are each
formed with a fork which embraces the spindle of the revolving pads.
When the belt shifter bar is slidden forward by the action of a treadle, the
connecting rod acting upon the rocking shaft allows the spindles to drop and bring
the pads into action. As soon however as the belt is shifted from the fast to the
loose pulley, the spindles will be raised, and the pads lifted clear of the plates. To
prevent the spindles falling too low, and to adjust the pressure of the pads upon
the plates, the spindles when down bear upon adjusting screws.
To prevent the loss of time consequent upon the stopping the machine to change
the foul surfaces of the canvas which is stretched over the cleaning pads by means
of rollers situate at opposite sides thereof, an automatic rotary motion is given
to these rollers by means of a worm and worm wheel, the latter being keyed to
the axle of the winding-on roller. The worm spindle is fitted with a ratchet
wheel, into which takes a pawle carried by a lever that swings on the worm
spindle, and is carried round with the revolving apparatus. The tail of this lever
as the apparatus revolves, strikes against a fixed stop, and the lever is thereby
driven (against the pressure of a retarding spring) together with its pawle, which
imparts an axial motion through the ratchet wheel worm and worm wheel to
the winding-on roller. A tension or brake device is applied to the canvas delivery.
roller, so that the fabric will be always held at tension.
For the purpose of removing the ink froin the polishing pads and of giving them
a surface sufficiently smooth to polish the plates, they are made to pass over an
endless travelling apron, which is kept in proper condition by being first dusted with
whiting to dry the ink which it has received from the pads, and afterwards brushed
to remove the same therefrom. The dusting is effected by causing a cylinder of
wire gauze charged with powdered whiting to rotate slowly above the apron as
it passes over a drum, to which fixed brushes are applied to remove the loose
particles from the travelling apron; the pressure of these brushes may be adjusted
screws.