IMPROVEMENTS IN MACHINERY FOR MOULDING INDIA-RUBBER AND OTHER PLASTIC MATERIALS
Year: 1872

page_text: PROVISIONAL SPECIFICATION left by Alexander Melville Clark at the
Office of the Commissioners of Patents, with his Petition, on the
15th November 1872.-A communication from abroad by Manuel
Léopold Jonas Lavater, of Paris, France.
I, ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the
County of Middlesex, Patent Agent, do hereby declare the nature of the
said Invention for "IMPROVEMENTS IN MACHINERY FOR MOULDING INDIA-RUBBER
AND OTHER PLASTIC MATERIALS," to be as follows:-
This Invention relates to moulding articles in india-rubber and other
plastic materials. The sheets of rubber from which combs are made
are moulded with half round ribs on either side to form the round back
of the comb, which is cut out of the sheet, the stiffness of the comb
being dependent on the thickness of the back.
In the ordinary methods of moulding these articles two plates of
metal are employed, each having grooves of suitable form on the
face. A thin sheet of tin to serve as a mould is placed on each side of
the sheet of soft rubber, which is then inserted between the metal

page_text: plates and subjected to the action of an hydraulic press. The objection
to this method is that the tin does not expand sufficiently to conform
accurately to the grooves in the plates, so that the plastic material is
prevented from entering, and the hollows are imperfectly filled up.
For instance, supposing the groove to be semicircular in section the
ribs produced on the surfaces of the rubber would be of a flattened
irregular shape.
The same objection applies in the case of those circular or cylinder
presses in which the grooves or raised surfaces are in concentric rings,
as the tin not only fails to fit the grooves as in the former instance, but
is moreover drawn up when brought between the two cylinders.
According to this Invention the above objections are obviated, as
instead of using plates, or grooving the cylinders concentrically as
before mentioned, I groove them longitudinally or in lines parallel to
their axes, the grooves in the two cylinders meeting exactly at each
revolution. By this novel arrangement and under pressure of the
plastic material itself the sheet of tin or other metal, or it may be
paper or other fabric, will readily adapt itself to the grooved or raised
surfaces on the cylinders. By this means the plastic material is enabled
to accurately take the form of the grooves, and the tin having the exact
configuration of the cylinders serves as a mould during the vulcani-
zation. Further, in order to ensure that the corresponding mouldings on
the two sides of the plates shall exactly meet, I mount the wheels by
which the two cylinders are geared together on either end of the cylinders
themselves, within the framing of the machine, and not on their journals
as heretofore, one of the cylinders being also geared outside the framing
with the prime mover.
The accompanying Drawing illustrates, a moulding machine arranged
according to this Invention. Figure 1 is a side view and Figure 2
a sectional elevation of the machine on line 1-2, Figure 1, while
Figures 3, 4, and 5 show sections of portions of pairs of moulding
cylinders with grooves of various forms. The reference letters apply
to all the Figures.
a, b, pair of moulding cylinders rotating in opposite directions for
producing the ribs or flutings on both sides of the sheet of rubber c, to
form the rounded backs of the combs. The surfaces of the rollers are
for this purpose grooved at d, d, of the desired form, the grooves

page_text: being made longitudinally or parallel to the axes of said rollers.
e, e, Figures 3, 4, and 5, are thin sheets of tin placed on each side of
the sheet of plastic rubber c. The cylinders a, b, are made hollow, and
heated by a jet of steam supplied by a pipe ƒ from a generator and
escaping at pipe g. The cylinders may however be heated in any
other manner. h, h, side frames of the machine united by cross ties i, i;
j, j, journals of lower cylinder or roller b, mounted in bearings k, k, on
framing h; 1, 2, journals of upper roller a, mounted in bearings m,
adjusted by screws n, turning in sockets on the framing, and simul-
taneously operated by a horizontal worm shaft p, gearing with worm
wheels o, o. By turning hand wheel q of shaft p the roller a may be
readily adjusted in position with regard to roller b, according to the
desired thickness of the combs to be produced. r, r, toothed wheels
carried on the ends of the rollers a, b, inside framing h, and gearing the
same together, the lower roller 6 receiving rotary motion from the
driving shaft t, carrying the fast and loose pulleys u, y, which is
communicated to the upper roller a in the opposite direction to b, by the
gearing a³, b³, c¹³, d³.