AN IMPROVED PROCESS AND APPARATUS FOR MOULDING HOLLOW ARTICLES OF CELLULOID OR SIMILAR PLASTIC MATERIAL
Year: 1881

page_text: LETTERS PATENT to William Robert Lake, of the Firm of Haseltine, Lake,
& Co., Patent Agents, Southampton Buildings, London, for an Invention of
"AN IMPROVED PROCESS AND APPARATUS FOR MOULDING HOLLOW ARTICLES
OF CELLULOID OR SIMILAR PLASTIC MATERIAL." A communication from
abroad by William B. Carpenter, of Newark, New Jersey, United States of
America
COMPLETE SPECIFICATION filed by the said William Robert Lake at the
Office of the Commissioners of Patents on the 1st February 1881.
WILLIAM ROBERT LAKE, of the Firm of Haseltine, Lake, & Co., Patent Agents,
Southampton Buildings, Loudon. "AN IMPROVED PROCESS AND APPARATUS
FOR MOULDING HOLLOW ARTICLES OF CELLULOID OR SIMILAR PLASTIC
MATERIAL." A communication from abroad by William B. Carpenter, of Newark,
New Jersey, United States of America.
This Invention relates to improvements in the manufacture of hollow articles of
various kinds froin plastic materials. It comprises an improved process or method
of moulding articles from a blauk tube of any material capable of being rendered
plastic by heat, such, for instance, as celluloid or the like; also an improved machino
for carrying the said process into practice; also forming the dies or moulds with
hollow backs for the circulation of heating and cooling fluids; also the formation of
conical openings in the recesses of the moulds for venting the same; also the
combination of a fluid conductor with a plugging device; also the combination
with the plugging device of an internal mandrel and elastic stopper; also the
connection of a pressure gauge with the interior of the moulded article, and the
combination of hot and cold water pipes with the die-beds.
My said Invention is applicable for moulding dolls' heads, noses, and other articles
of irregular shape, and is shown in the accompanying Drawings as applied to the
moulding of ladies' powder boxes, three of which are seen connected together as
moulded, they are afterwards provided with bottoms by a separate process.
My improved moulding process consists in the following operations, that is to
say-First, in clamping a piece of tube in a separate die; secondly, in providing
each end of the tube with a plug or stopper adapted to be tightened by degrees;
thirdly, in circulating steam or hot water entirely through the tube conjointly
with the heating of the dies by a circulation in their interior; fourthly, in tightly
[ Evian 77

page_text: stopping the ends of the tube when at the proper temperature, and applying an
internal pressure to force the tube into the mould; fifthly, in checking and holding
the pressing fluid within the mould when the proper pressure is indicated by the
gauge; and, sixthly, in circulating a cooling fluid in the backs of the dics or mould
parts to harden the moulded articles in the desired shape.
SECTION OF the same on the fine, Figure 1.
Figure 3 is a vertical section of a mould and die-bed drawn to an enlarged scale,
and
Figure 4 is a view of the back of one of the moulds also drawn to an enlarged
scale.
Figure 5 is a section on the line x¹, x', Figure 3.
Figure 6 is a plan, and
Figure 7 an edge view of the elastic stopper.
Figure 8 is a longitudinal section of the mandrel with the screw in its place, as
hereinafter described.
A is the arch of the press sustaining the nuts through which the screws operate;
B is the bed of the press, to which the arch may be cast or bolted as preferred;
C, C, are the dies or parts of the mould; D is the screw to operate the plugging
device; D is the screw to clamp the dies together; E, E, the ribs on the bed to
carry the die and die-beds; F, F, are the die-beds on which the dies are bulted;
Gis the plug or plugging core swivelled upon the screw D and provided with
apertures a leading from the lower end to a pipe g, for conducting steam or water
into the tube b; g¹ is a gauge applied to the pipe g to indicate the pressure in the
tube or mould; d is a cock in the pipe g to regulate the flow; hand c are hot and
cold water pipes provided with cocks h¹ and c', and u is a waste pipe to allow a
circulation through the dies when desired; u is the cock in the same; e is an
elastic stopper placed in the lower end of the tube before inserting it in the dies,
and is a mandrel to compress and expand the same as the plug G is gradually
closed. The mandrel is also inserted in the tube with the stopper e, and the lower
end of the plug G is hollowed to fit the rounded top of the mandrel, and forces it
downward upon the stopper e, which is made a little smaller than the tube, or with
indented edges, as shewn in Figure 6.
The dies are shown of similar farm and arranged opposite to each other as the
article illustrated (a powder box), is of circular shape, but the dies may be of any
desired shape, and are hollowed out or formed with spaces S in their back for the
circulation of water or steam.
The die-beds F are shown of rectangular shape, and the dies are bolted to their
opposite faces by screws i inserted through the beds into holes j tapped into the
back of the dies.
Holes are shewn in Figures 3 and 5 for the introduction of the various
connecting pipes by which the fluids are conducted into the spaces S behind
the dies.
The operation of the dies is effected by securing one of the die-beds to the arch A
at one side of the press, and the other to the point of the clamping screw D¹,
exactly opposite.
The die-bed is provided with a socket upon its back, into which the point of
the screw is swivelled like the screw D in the plug G by a pin m and groove n in
the point or neck of the screw.
The dies being fitted, or the die-beds if preferred, to the ribs E upon the bed of
the press, they are guided steadily to and fro in their opening and closing, and
they may also be provided with dowels o to fill holes in the face of the opposite
die.

page_text: The process of making a hollow article with this mechanism is as follows, that is
to say-The dies are separated and the cock opened to admit hot fluid which
circulates behind the backs of both dies, and passes out through the waste pipe u.
The tube b from which the object is to be moulded, is used of cylindrical tapering
or any desired shape that can be produced without the aid of my apparatus, and
is adapted to nearly fit the apertures t, t', at the top and bottom of the dies (sec
Figure 3).
The elastic stopper c is inserted in the bottom of the tube and the mandrel f
placed upon it with its upper end extending nearly to the top of the tube, which
is then put in its place in the press and the dies closed upon it. The plug G is
then forced into the upper end of the tube by its screw D, and the force employed
is not sufficient to make a water-tight joint at the point of contact, so that the
fluid introduced through the pipe is at liberty to escape and make room for a
fresh supply. The shape of the stopper e also permits the circulation of steam or
hot water introduced through the whole length of the tube by allowing a leakage
at the bottom joint. This leakage at the top and bottom of the tube is caught in
tauks Tappiled to the sides of the bed B, and shewn in the Drawing as cast in
one piece therewith, a pipe P conducting the liquid to a sewer as desired. The
tube is thus heated and softened simultaneously with the heating of the dies, and
the plug G is then forced down further into the tube to close the same tightly at
the top by its conical shape, and at the bottom by the expansion of the elastic
stopper c under the pressure exerted upon the top of the mandrel ƒ.
To secure the proper adjustment of this mandrel I construct it with a threaded
socket near the bottom, and insert therein a screw y (see Figure 8) provided
with a jam nut . By inserting a rod in the holes formed in the screw and
socket the length of the mandrel may be altered to suit a great variety of dies,
and adjusted to compensate for the wear of the stopper e, which is preferably made
of iudia-rubber.
The pipe is preferably connected with a steam boiler, as the primary heat and
ultimate pressure required are thus secured without the use of any force-pump, and
the boiler pressure is thus exerted in the pipe b when its ends become water-tight.
The gauge g indicates when the pressure reaches the maximum desired, and the
cock d is theu closed, and the circulation in the back of the dies changed from hot
to cold water, to barden the moulded article while under tension in the dies.
The condensation from the pipe g suffices to fill the pipe with water when being
heated, and the pressure in the interior of the tube is thus maintained while it is
cooling even if the cock dis closed. If desired this cock may be left open to
maintain a supply until the cold circulation has had the desired effect, the tempera-
ture of the dies serving to reduce the contents of the tube to its own degree of heat,
notwithstanding its connection with the boiler.
When the moulded article is chilled, it may be taken from the dies by opening
the same, and retains perfectly its form and any ornamentation that may be
engraved within the dies.
To permit the escape of air or water from the dies I find it desirable to furnish
vents in the bottom of the recesses, as at u and vin Figure 3. These vents require
to be very minute to prevent the penetration of the moulded material, and I
therefore give them a couical form with their base at the back of the die, and their
apex entering the recesses to be veuted. "By the use of these holes the hot water or
steam, first circulated to heat the dies, is thrown into the die outside the tube, and
aids materially in heating the tube uniformly, while the holes afford a free escape
for the heating fluid under the pressure of the tube expanding to fill the mould.
In some instances the mandrel finay be dispensed with, for instance in moulding
tubes having one end closed, as unbrella handles and the like.
From the above description it will be seen that my process is partly independent
of the mechanism I have described, as the mould may be clamped by screws
independently of the parts A, B, D, and supplied with the heating and cooling
devices in a series of machines instead of a single one provided with all needful

page_text: appliances. I do not therefore limit myself to the precise construction and
arrangement of the parts above described.
Having thus fully described the said Invention as communicated to me by my
foreign correspondent, and the manner of performing the same, I wish it understood
that I claim,
First. The method, substantially as herein described, of forming hollow articles
from a blank tube of celluloid or similar plastic material by heat and pressure
applied to the interior of the tube in suitable inoulds.
Second. In a machine for forming articles of celluloid or similar plastic material,
the frame, the screws D, D', the die-beds, and the plug G operating in combination
with the dies, substantially as above described and as shewn in the Drawing.
Third. The conical apertures, in combination with the recesses in the dies and
connected with the spaces S or suitable outlets for the vented fluids, for the purpose
herein set forth.
Fourth. In combination with the movable plug G, the inlet pipe g, and one or
more apertures a, for supplying the interior of the tube b, as above described.
Fifth. The combination of the plug G with the mandrel and expansive stopper
e, as and for the purpose herein set forth.
Sixth. In combination with the plug for conducting the desired pressure to the
interior of the tube b, the boiler or other reservoir of pressure and the gauge,
substantially as and for the purpose specified.
In witness whereof, I, the said William Robert Lake, have hereunto get my
hand and seal, this First day of February, in the year of our Lord One
thousand eight hundred and eighty one.