IMPROVE- MENTS; IN MACHINERY OR APPARATUS FOR ENGRAVING OR PRODUCING PRINTING SURFACES
Year: 1858

page_text: PROVISIONAL SPECIFICATION left by John Chadwick at the Office of
the Commissioners of Patents, with his Petition, on the 18th February
1858.
I, JOHN CHADWICK, of Glasgow, in the County of Lanark, North Britain,
Engraver, do hereby declare the nature of the said Invention for "IMPROVE-
MENTS; IN MACHINERY OR APPARATUS FOR ENGRAVING OR PRODUCING PRINTING
SURFACES;" to be as follows, that is to say:-
The other or
This Invention relates to the arrangement and construction of machinery or
apparatus for effecting the operation of engraving cylinders or other surfaces,
or the production of printing surfaces by self-acting means. Under one
modification the machine consists of a pair of end standards connected near
their upper parts by two transverse, ribs arranged parallel to each other like
the bed of an ordinary lathe. The upper extremity of each of the end
standards carries a mandril, one end of which is squared and works between
lateral antifriction'rollers, and also upon another antifriction roller fitted beneath
the mandril end. These rollers are capable of accurate adjustment both in
lateral and vertical directions; by means of nuts and screws.
inner, end of each mandril is made with an external screw, on,which is screwed
the clutch or holder for holding the end of the cylinder or surface to be
engraved. Motion is communicated to the mandrils and the copper or other
cylinder to be engraved by suitable driving gear, which gives motion to an
eccentric or cam, so as to give an intermittent motion to the cylinder or surface
to be engraved, or a partially rotatory motion to and fro may be communicated
by suitable cams or eccentrics specially designed for the purpose. The cylinder
is moved to and fro in a horizontal direction by means of a worm and worm
wheel actuated from the driving gear of the machine. The slide which

page_text: carries the mechanism for actuating the punch or engraving tool traverses
on the bed of the machine, and is actuated by a screw shaft put. in motion
by the driving mechanism. To the slide is fixed a tubular rod, which carries
at its upper extremity a horizontal arm, and this arm is fitted to a stem or rod
which slides up and down in the fixed tubular rod. One end of the arm projects
over the cylinder, and carries at that end a weight in which the punch or
other engraving tool is held. The pressure of the punch or engraving tool is
regulated by india-rubber springs fitted within the tubular rod, and it is raised
or lowered by means of a suitably-shaped eccentric or cam. The other end
of the horizontal arm, which carries the punch or other tool, has jointed to it
a weighted rod; this rod is pendant from the horizontal arm, and at its lower
end is acted upon at intervals by an eccentric fitted upon a spindle running
parallel with the bed of the machine.
An intermittent motion is given to the
eccentric by means of segmental racks fitted at each end of the spindle, and
driven by suitable gearing. When the eccentric presses against the weighted
rod it turns upon its point of support, and allows the engraving tool to rise
from the cylinder. Upon the pressure of the eccentric being, removed, the
weighted arm falls back to its vertical position, and the tool is brought down
upon the cylinder. This arrangement of mechanism admits of one, two, or
other number of punches, mills, or engraving tools being used simultaneously
or intermittently upon the cylinder or other surface to be engraved. In place
of using toothed wheels for giving rotatory motion to parts of this or other
machinery, the periphery of one wheel may be made with a series of points or
nipple-like projections, which take into corresponding depressions made in the
periphery of the fellow wheel or pinion. This mode of constructing wheels
and pinions prevents "back lash." By means of these mechanical arrange-
ments for moving the cylinder or the engraving tool or tools in any desired
direction, a vast variety of patterns may be engraved upon the printing surface
by a simple change of the cams or eccentrics by which the motions of the
cylinder or tool are varied as required. So also, by changing or varying the
action of the cams or eccentrics, the machine may be made to design patterns,
as well as copy those already designed.
The ordinary engraving machines may also be made to work according to
the general system herein-before described by the employment of "mills"
differently actuated for the production of the various lines of figuring
required.