IMPROVEMENTS IN AND RELATING TO STEREO- TYPE AND OTHER PLATES FOR PRINTING
Year: 1882

page_text: PROVISIONAL SPECIFICATION left by William Robert Lake at the Office
of the Commissioners of Patents on the 19th April 1882. A communi-
cation from abroad by Joseph Augustin Heuse and Georges Jouanny, both of
Paris, France.
"
WILLIAM ROBERT LAKE, of the firm of Haseltine Lake & Co Patent Agents,
Southampton Buildings, London, IMPROVEMENTS IN AND RELATING TO STEREO-
TYPE AND OTHER PLATES FOR PRINTING." A communication from abroad by
Joseph Augustin Heuse and Georges Jouanny, both of Paris, France.
The present mode of bending stereotype and other plates designed to be fixed on
the cylinders of rotary machines for printing purposes, is susceptible of great
disadvantages, the chief of which are, first, it is rough because the means employed
to effect the bending requires a strong apparatus upon which is exerted considerable
mechanical force which destroys by its action the fine lines of engravings or crushes
the small letters upon the said plate; second it is imperfect by reason also of the
mechanical bending; the design or picture which is to be reproduced by the impression
suffers a deformation or distortion in one direction which involves inaccuracies of
proportion and which may disagreeably affect the appearance of the design or
picture; third, it is costly because it necessitates a long and complicated subsequent
preparation of the plate in order to destroy the effect of the inequalities which
result from it.
The object of the present invention is to reduce to its lowest proportions the
effect of this deformation or distortion. In order to bend with the greatest facility
an electro-plated or metallic stereotype plate its thickness must be considerably
reduced, but other difficulties have arisen in fixing it on to the cylinder of the
rotary machine. The smallest thickness, to which they have been reduced is 8 or 9
millimetres. Experiments which have been made upon several materials such as
iron, lead, tin, cardboard, and others, have shewn that in them all the interior
circumference or rather the interior arc of the curved plate remains equal to the
rectilinear dimension which the surface of the plate had before bending, the exterior
arc only suffers an elongation in proportion to the thickness of the material, that is
to say the difference in the radii of curvature of the two arcs will be greater as the
thickness of the plate is increased.

page_text: The said invention consists essentially in preparing the said stereotype plates by
providing them with a series of parallel grooves. If the plate has a thickness of
10 millimetres the grooves will have a depth of 8 millimetres, for example;-the
bending has then no more effect than it would have upon a plate of 2 millimetres
in thickness, it is in fact, the same as if the plate to be bent had only a thickness
of 2 millimetres. When the plate is thus constructed it is very easily bent even
for cylinders of very small diameter but the smaller the diameter of the cylinder
the nearer together the grooves should be. Blanks or spaces may be arranged in
the grooved part in order to reduce the weight of the plate
To effect the operation of bending the plate it is not even necessary to employ a
special apparatus, it is sufficient to place the plate on a heated block having the
same curvature as the cylinder which is to receive the said plate, and to exert upon
the plate a light-pressure in proportion to the amount of bending required. After
this operation and the cooling of the plate when the angles of the grooves are
near each other, the plate is as rigid as if it were of the larger thickness
throughout.
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By this method of bending, the plate remains intact because it is only subjected
to a light pressure and not to any violent shock or blow which would impair the
fine lines of an engraving, or the smallest and most delicate letters. Prepared as
herein before described the plate may, after it has been used, be again curved more
or less so that it may be placed on another rotary machine in which the cylinders
are larger or smaller in diameter. The plate may, if necessary, be brought back
to its original form and then used upon a flat machine. This method has the great
advantage of not requiring any change from the metal ordinarily used for stereotype
plates.