Improvements in Matrix Plates for the Production of Curved Electro- type Plates.
Year: 1889

page_text: Date of Application (in United Kingdom), 12th June, 1889
Complete Specification Left. 12th June, 1889-Accepted. 10th Aug., 1389
COMPLETE SPECIFICATION.
Improvements in Matrix Plates for the Production of Curved Electro-
type Plates.
We, GILBERT HARTWELL BENEDICT of Ellenville, Ulster County, in the State of
New York, United States of America, printer and PATRICK MOSES FURLONG, of
Albany, Albany County, in the State of New York, United States of America,
printer, do hereby declare the nature of this invention and in what manner the
same is to be performed to be particularly described and ascertained in and by the
following statement :-
Our invention relates to improvements in devices used in the production of curved
electro-type plates the curvatures of which must conform to that of the surface of the
printing cylinders in cylinder presses, upon which these plates when produced, are
mounted in a manner well understood by those skilled in the art of printing.
Prior to our present invention we have produced curved electrotype-plates to be.
used in cylinder presses, in the following manner; A rectangular plate of uniform
thickness, made of sheet steel, hard rolled brass, or other highly elastic metal, was
bent to set to the arc of a circle whose radius was slightly larger than the radius of
the cylinder of the press upon which the electrotype plate was intended to be used.
This plate was then unbent and clamped to a rigid flat bed-plate in such manner that
its original curved set was not affected, so that when released from the clamp it would
again assume its original curvature. The curved elastic plate, thus flattened out
upon a rigid support, was then used as the support upon which the moulding material
was poured in a layer of uniform thickness, and after this material had attained the
desired hardness, and its surface had been well impregnated with graphite or other
suitable conductor of electricity an impression of the type or other relief printing
form was produced upon the moulding material. This furnished a matrix, which was
then shaved, trimmed, built up, and otherwise prepared to receive an additional
treatment with graphite. The clastic plate was then released from the clamp, and it
again assumed the original curvature, thereby bending the matrix which it supported
to the curvature of the cylinder of the printing press, or nearly so. From this
matrix electrotype-plates were made by inserting the same into a depositing bath in
proper relation to a convex anode, as is well understood by those skilled in the art.
In the process thus briefly described great difficulties were experienced, the principal
difficulty consisting in the fact that when the curved plate was clamped upon the flat
rigid bed-plate it would buckle near the middle and sometimes in other places, to such
extent that the moulding material could not receive and retain a clear and sharply defined
impression of the printing form. This buckling we found to become the more serious
the smaller the radius of curvature and the greater the width of the elastic plate was,
and our process which otherwise yielded excellent resuits, had to be confined to the
production of electro-type plates for printing cylinders of comparatively large diameter
Even within that limited range a great number of the newly prepared elastic plates
had to be discarded, and others, which at first seemed to be unexceptional, would after
repeated use hegin to buckle.
It is the object of our present invention to overcome this buckling of the curved

page_text: -
elastic matrix plates, and we have, discovered that this may be accomplished to
perfection by reducing the mass of the matrix plate from the middle line of the
curvature toward the two edges, either continuously or in graduated steps. Thus
constructed the set curvature of the matrix plates may be much greater-i.e. the
radius of curvature may be much smaller than has heretofore been found practicable-
and whatever that curvature may be no buckling can be found in the plate when
flattened out to receive the moulding material, while its elasticity is not impaired in
the least by the reduction of its mass from the middle toward the edges in the direction
of the curvature.
With certain forms of the matrix plate the clamp-frame is specially constructed
and this particular construction of the clamp-frame forms another feature of our
invention, all of which will more fully appear from the following detailed description
with reference to the accompanying drawings, in which we illustrate, in
Figure 1 a cross section of one form of our improved elastic matrix plate with the
matrix material thereon, in position in the clamping-frame when the lid of the latter
has been raised; Fig. 2 a plan view of another form of our improved matrix-plate
flattened out in the clamp-frame; Fig. 3 a cross section on the line fig. 2;
Fig. 4 is a cross section of another form of our matrix plate inserted in the clamp-
frame with the lid of the latter raised. Fig. 5 is a plan view of still another form
of our improved matrix plate. Fig. 6 is a view of a section on line y y Fig. 5.
Figs. 7 and 8 are like views of modification thereof. Fig. 9 is a sectional view on
line of Fig. 2.
Like numerals of reference indicate like parts in all the figures of drawings.
Referring now more particularly to Figs. 1, 2 and 3 the clamp frame is there
shown composed of the bed-plate I, which has the general quadrangular shape indicated
by the whole clamp in figure 2, and of the open frame 2, hinged to one edge of the
bed plate, as indicated at 3 3. A bar 4 provided with an offset on its under side and
extending between the hinges 3 3 is secured to the bed-plate so that a recess or
groove 5 is formned near the rear edge of the bed-plate for the insertion of one edge
of the curved matrix plate as will hereinafter more fully appear.
The hinged open frame 2 consists of two side bars 66 and a front bar 7 which are
either joined together or which may all be made in one piece of L-iron and of such
size that the depending flanges 8 of the L will just pass over the edges of the bed-
plate. Two clasps 99 pivotted to the front bar 7 are adapted to secure the open
frame to the bed-plate when the former is turned down upon the latter, as shown in
figs. 2 and 3 the under side of the front edge of the bed plate being formed with
offsets 10 as shown to allow the lower jaws of the clasps to pass under said edge
and in the depending flange 8 of the front bar 7 of the frame are formed corre
sponding slots 21 to receive the upper jaws of the clasps as shown in Fig. 9.
It will now be understood that if a rectangular plate of any kind having the size
of the bedplate, as limited by the rear end of recess 5 be placed in position upon
said bed-plate with one edge inserted into said recess and the open frame be then
turned down and clasped said rectangular plate will be securely clamped in position
upon the bed plate. In this position there will be a guard of uniform height all
.around the clamped plate formed on three sides by the upper flanges 8¹ of
the L-irons and on the fourth (the rear) side by the bar 4 extending between the
hinges 3 3.
In Fig. 1 one form of our matrix plate is shown at 11. It is made of sheet
steel, brass, or other like elastic metal and is bent to set to the are of a radius which
is somewhat larger than the radius of the cylinder upon which the electro-type is to
be used. As shown in the drawings the matrix plate 11 is not of uniform thickness
but is reduced in thickness from the middle line of curvature toward the
edges 12 12 in such manner that when the plate is flattened out upon the bed-
plate, as indicated in dotted lines, its upper surface represents a true plane while the
under surface is slightly convex. To accomodate the bed-plate to this convexity
a gentle concavity is formed in its upper surface, as is shown somewhat exaggerated
in the drawings. Thus the mass of the matrix plate is gradually and continuously

page_text: reduced from the middle line of curvature toward the edges in the direction of the
curvature ; and by this construction the main object of our invention is accomplished.
In use the rear edge 12' of the matrix plate is inserted into the recess 5 as shown in
Fig. 1 and the hinged open frame is turned down upon the bed plate whereby the
flanges 81 of the former engage and press down the edges of the matrix plate and the
latter is flattened out upon the bed plate as shown in dotted lines in Fig. 1, and in
connection with another form of our matrix plate in Figs. 2 and 3. The clasps 99
are then turned to engage the under side of the front edge of the bed plate and in
this condition the matrix plate is ready to receive the moulding material 13.
By the unbending of the matrix plate (without disturbing its permanent set) and
by the clamping of its edges in the clamp frame a new distribution of the mass of the
plate takes place and when the matrix plate is of uniform thickness as heretofore,
this new distribution of mass gives rise to buckles, which destroy the usefulness of
the plate, as herein before explained; but when the mass of the plate is originally
reduced towards its edges in accordance with our invention, the new distribution of
mass accompanying the unbending of the plate takes place without perceptible buckling
and the matrix plate rests upon the bed plate in intimate contact at all points so that
the subsequent preparation of the matrix is accomplished without flaws. When
clamped in position, the flanges 8¹ of the open frame form a guard of uniform height
around the edges of the matrix plato, so that the frame constitutes at the same time
a molding clamp and a molding pan, and in this molding pan the molding material 13
is poured and is allowed to set to the required hardness or consistency. The surface
of the molding or matrix material is then impregnated with graphite, the impression
with the type or other relief form is made, and then an additional treatment with
graphite is ordinarily resorted to whereby the matrix surface becomes highly polished
and in condition to receive the galvano-plastic deposit of copper or other metal. The
object of the use of a curved elastic matrix plate however is to curve the matrix to
conform to the surface of the cylinder of the printing press, and this curvature is
produced before the matrix is inserted into the electro-depositing bath. This is done
by unclamping the matrix plate as shown in Fig 1 when by its own elasticity it will
curve back to its original form and will bend the plastic matrix to the same curvature
as shown. This statement should be modified in so far as the curvature of the concave
exposed surface of the matrix being concentric with the concave surface of the matrix
plate will be curved upon a slightly smaller radius than the matrix plate so as to
conform exactly to the surface of the cylinder of the press. The matrix is then
removed from the elastic matrix plate and the electrotype plates are produced in any
ordinary or improved manner well understood by those skilled in the art.
In Figs. 2 and 3 the matrix plates are shown constructed in accordance with our
invention, in a different manner. Instead of reducing the mass of the plate toward
the edges by a gradual reduction of thickness as in the form shown in fig. 1, we
here achieve the same object by a series of slots cut into the plate which is now made
of uniform thickness.
By reference to Fig. 2 it will be seen that at about the middle line of the matrix
plate a strip 14 of moderate width is left intact, and that on each side of that central
strip or belt there is a series of evenly-spiced narrow slots, 15 15, which extend in
the direction of the curvature toward the edges of the plate. Another series of similar
slots 16 16 is produced on each side of the slots 1 15. These slots 16 16 are slightly
wider than the slots 15 15 and are nearer to the edges of the matrix plate
and additional series of slots 17 17, 18 18 &c. increasing in width and preferably
decreasing in length are continued to the edges of the plate, and the slots of the last
series extend out through the edges of the plate as shown in fig. 2 whereby these
elges become discontinuous and comb like. By this construction the mass of the
matrix plate becomes reduced step by step toward the edges in the direction of the
curvature and the buckling of the plate is completely overcome. This construction is
in some respects proferable to that shown in Fig. 1. In the first place it is much
easier to make and consequently cheaper; in the second place the molding material
Howing into and filling the slots in the plate adheres better to the latter so that when

page_text: the plate is released from the clamp frame after the matrix material has been applied
the latter cannot peel off, as is sometimes the caso when the matrix plate presents an
unbroken surface.
In Fig. 4 a modification of the form of matrix plate shown in fig. 1 is illustrated.
In this construction the reduction of the mass of the plate is accomplished by cutting
planing or grinding a series of facets 19 19 on the under or convex side of the plate.
In figs. 5 and 6 a modification of the construction shown in Figs. 2 and 3 is
illustrated. In this case in place of the slots 15 16 &c. a series of grooves 20 20 is
formed in the under side of the matrix plate these grooves being grouped in
series and graduated in length, width or depth or in all theso respects to produce
a step by step diminution of the mass of the plate toward the edges the same as the
slots in the construction shown in figs. 2 and 3. The grooves may have any desired
form i.e. they may be curved as shown in figs. 5 and 6, rectangular as shown in
fig. 7, or V shaped as shown in Fig. 8; or they may be shaped to any other
convenient form.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed we declare that what we
claim is;
1. An apparatus for producing curved matrices for electrotype plates consisting
essentially of a curved elastic matrix plate having its mass reduced from the middle
toward the edges in the direction of the curvature and a clamping frame for flattening
the matrix plate provided with guards for the retention of the matrix material
substantially as described.
2. An elastic matrix plate for the production of electrotype plates for cylinder
presses having a set curvature corresponding to the curvature of the printing cylinder
of the press and having its mass reduced from the middle line to the edges in the
direction of the curvature substantially as described.
3. A matrix support for the production of electro-type plates for cylinder presses
consisting of a plate of spring metal bent to a definite set curvature and having its
mass gradually reduced from the middle toward the edges in the direction of the
curvature whereby the matrix plate may be flattened out without buckling to receive
the matrix material and to recurve to its original shape when released substantially
as described.
4. A matrix support for the production of curved electrotype plates for cylinder
presses consisting of a plate of spring metal bent to a definite set curvature and
having its mass reduced step by step from the middle toward the edges in the direction
of the curvature substantially as described.
5. A matrix support for the production of curved electrotyra piates for cylinder
presses consisting of a plate of spring metal having parallel series of sluts from near
the middle to the edges in the direction of the curvature substantially as described.
6. A matrix support for the production of curved electrotype plates consisting of a
plate of spring metal having its mass reduced from the middle toward the edges in
the direction of curvature by a series of perforations substantially as described.
7. A matrix support for the production of curved electrotype plates for cylinder
presses consisting of a p'ate of spring metal bent to a definite set curvature approxi-
mating the curvature of the cylinder of the printing press.
8. A clamp for curved elastic matrix supports consisting essentially of a flat bed
plate and a frame fitted to the bed plate constituting a clamp jaw and a molding guard
for the same substantially as described.
Dated this 12th day of June 1889
W. P. THOMPSON & BOULT,
Agents.