IMPROVEMENTS IN APPARATUS FOR THE MANUFACTURE OF BASES FOR ARTIFICIAL TEETH
Year: 1881

page_text: LETTERS PATENT to Alexander Melville Clark, of 53, Chancery Lane, in the
County of Middlesex, Patent Agent, for an Invention of "IMPROVEMENTS IN
APPARATUS FOR THE MANUFACTURE OF BASES FOR ARTIFICIAL TEETH."
A communication from abroad by Joseph Duchesne, of Marseilles, France.
PROVISIONAL SPECIFICATION left by the said Alexander Melville Clark
at the Office of the Commissioners of Patents on the 20th April 1881.
ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the County of
Middlesex, Patent Agent. "IMPROVEMENTS IN APPARATUS FOR THE MANUFACTURE
OF BASES FOR ARTIFICIAL TEETH." A communication from abroad by Joseph
Duchesne, of Marseilles, France.
This Invention relates to improved apparatus for the manufacture of bases for
artificial teeth of celluloid and indiarubber, whereby such articles may be quickly,
accurately, and cheaply made several at a time in the same flask, and of the same
or different materials (indiarubber or celluloid). Moreover by the apparatus of
this Invention the same piece may be lined with red, white, brown, or black
indiarubber according to the purpose required without opening the flask or allowing
it to cool.
The flask is made in two parts fitting together with a tongue and groove joint,
the lower part having a loose bottom fitting in a rebated opening, and on the
underside a circular flange which fits in a corresponding seat in the table of the
The upper part of
press and permits of the flask being turned round on its axis.
the flask has a loose cover with a central opening in it. The flask is thus made in
4 main parts altogether, which may be quickly fitted together and taken apart, the
two halves being locked together by. cotter bolts. The lower half of the flask is
provided with screw sockets or openings in the sides, in which to fix the nozzle of
the injecting cylinder, and also has holes in which are inserted pins hereinafter
referred to, the said holes being provided with pivoted covers.
Similar openings
may also be made in the upper half of the flask, if desired, for the same purpose.
The Invention is illustrated in the accompanying Drawings, in which Figure 1
D

page_text: is a front elevation, Figure 2, a side elevation, and Figure 3, a plan of the
improved apparatus for moulding dental-plates; Figure 4 is a vertical section, and
Figure 5, a horizontal section on line a, b, Figure 4, of the flask, to contain the
plaster mould; Figure 6 is a plan of the lower palf of the flask, containing the
plaster mould and two patterns of the dental plates in wax; Figure 7 is a plan of
the upper half of the flask, face uppermost; Figure 8 shows side, end, and sectional
views of the injector cylinder; Figure 9 represents a screw plug; and Figure 10,
one of the pins hereinafter referred to. A flask made in two halves with loose
bottom and cover; B, table of the press on which the flask is placed; C, circular
rim on the bottom of the flask, which fits in a corresponding seat in table B to
enable the flask to be turned round on its axis; D is the crosshead of the press;
and E is a clamping screw working through a nut in the crosshead; F, follower of
screw E; G, hand wheel; H, crosshead through which works the screw I. The
inner end of this screw is plain and acts as a plunger for the injector cylinder J,
which is screwed into a socket at the side of the flask A; K, pillars of the press
rising from bed plate L; M, arms fixed to pillars K to carry the crosshead H;
N, spirit lamp for heating the flask; O, tube screwing into the top of the flask for
the reception of a thermometer, which may however be attached directly to the
injecting cylinder by means of a screw ring; P, pins inserted in holes in the side of
the flask when running in the plaster to form channels therein for the injection of
the material into the cavities of the mould; P¹, other pins also inserted at the time
of running in the plaster to form vents for the escape of the surplus material
injected; Q, are vent holes in the lower half of the flask for the escape of surplus
material when other dental bases are being moulded; R, pivoted covers for closing
holes Q, Q, when the excess of injected material begins to escape; S, screw plugs,
screwing into sockets at opposite sides of the lower half of the mould, and each
perforated to receive one of the pins above referred to, the said plugs being
removable for fixing the injector cylinder J in their place.
The action of the apparatus is as follows:-The lower half of the flask is first
filled with plaster, in which are placed one or more wax patterns of dental plates,
care being taken that the points of the pins abut against the base and centre of
the patterns, as shown in Figure 6. The top half of the flask is then placed upon
the lower one and also filled with plaster and the cover applied, and the two
halves being locked together the flask is placed in the press and clamped down by
the screw E. When the plaster is set sufficiently the two halves of the flask are
separated, the wax patterns are removed by means of boiling water, and the
pins P, P¹, and plugs S are withdrawn, leaving holes in the plaster for the injection
and escape of the material. The two halves of the flask are then again united and
placed in the press, the nozzle of the injector cylinder is screwed into the socket in
place of one of the plugs S, the flask is clamped down, the spirit lamp being lighted
for the purpose of heating the flask. Either caoutchouc or celluloid is now placed in
the injector cylinder and slightly compressed by means of the screw plunger I.
When the flask and injector cylinder are both heated to about 130° C. .the
plunger I is screwed slowly into the injector cylinder, thereby forcing the
caoutchouc or celluloid gradually and continuously into the cavity of the mould.
When the whole of the material contained in the injector cylinder J has been
forced into the mould and the plunger has reached the bottom of the chamber the
material in excess will flow through the channels and out at the sides of the lower
half of the flask and the operation is terminated. The injector cylinder is then
unscrewed, and the flask, while still hot, is turned partly round in its seat and the
injector cylinder is screwed into the other socket, and after being heated more
caoutchouc or celluloid is injected into the other cavity of the mould. Several
dental plates may thus be produced at once at a single moulding and heating
operation, and the said plates may moreover be made of different materials
introduced either separately or together, or successively in the same cavity.
With this improved system of injector press and flask, the preliminary heating
of the flask, in the case of indiarubber is avoided, and several subsequent operations

page_text: upon the moulded articles hitherto required are rendered unnecessary, the articles
being produced with perfect accuracy in every respect, and without liability of the
teeth fastenings or plates becoming loose or deviating from their proper position.
Moreover, by the employment of the flask herein described the union of new with
old caoutchouc is perfect and the use of several different tools is rendered
unnecessary for obliterating the traces of junction or repair.
The above advantages are also obtained in the case of celluloid, as well as a
considerable saving in labor and material, more particularly in the case of small
plates, and in the repair of old plates and the addition of new teeth thereto.
Another advantage is that the apparatus may be used by unskilled operators.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Alexander Melville Clark in the Great Seal Patent Office on the
20th October 1881.
ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the County of
Middlesex, Patent Agent. " IMPROVEMENTS IN APPARATUS FOR THE MANUFACTURE
OF BASES FOR ARTIFICIAL TEETH." A communication from abroad by Joseph
Duchesne, of Marseilles, France.
This Invention relates to improved apparatus for the manufacture of bases for
artificial teeth of celluloid and indiarubber, whereby such articles may be accurately,
rapidly, and cheaply made, several at a time in the same flask, and of the same or
different materials (indiarubber or celluloid). Moreover, by the apparatus of this
Invention the same piece may be lined with, or partly made of, red, white, brown,
or black indiarubber, according to the purpose required, without opening the flask
or allowing it to cool.
The flask is made in two parts fitting together with a tongue and groove joint, the
lower part having a loose bottom fitting in a rebated opening, and on the underside
a circular flange which fits in a corresponding seat in the table of the press, and
permits of the flask being turned round on its axis. The upper part of the flask
has a loose cover with a central opening in it. The flask is thus made in four
main parts altogether, which may be quickly fitted together and taken apart, the
two halves being locked together by cotter bolts. The lower half of the flask is
provided with screw sockets or openings in the sides in which to fix the nozzle of
the injecting cylinder, and also has holes in which are inserted pins, hereinafter
referred to, the said holes being provided with pivoted covers. Similar openings
may also be made in the upper half of the flask, that is to say, in the movable
cover or disc, if desired, for the same purpose.
The Invention is illustrated in the accompanying Drawings, in which Figures 1
is a front elevation, Figure 2, a side elevation, and Figure 3, a plan of the improved
apparatus for moulding dental plates; Figure 4 is a vertical section, and Figure 5,
a horizontal section on line a, b, Figure 4, of the flask to contain the plaster mould;
Figure 6 is a plan of the lower half of the flask containing the plaster mould and
two patterns of dental plates in wax; Figure 7 is a plan of the upper half of the
flask face uppermost; Figure 8 shows side, end, and sectional views of the injector
cylinder; Figure 9 represents a screw plug; and Figure 10, one of the pins herein-
after referred to.
A represents the flask made in two halves with loose bottom and cover; B is
the table of the press on which the flask is placed; C is the circular rim on the
bottom of the flask, which fits in a corresponding seat in the table B to enable the
flask to be turned round on its axis; D is the crosshead of the press, and E is a
clamping screw working through a nut in the crosshead; F is the follower of
screw E, and G is the hand wheel for operating said screw; H is a lateral crosshead
through which works the screw I, which has a squared end for the application of a
wheel or spanner. The inner end of the screw is plain and acts as a plunger for the
injector cylinder J, which is screwed into a socket at the side of the flask A; K are
the pillars of the press rising from bed plate L; M are arms fixed to the pillars K to
carry crosshead H; N is a spirit lamp for heating the flask; O is a tube screwing
into the top of the flask for the reception of a thermometer, which may however be
attached directly to the injecting cylinder by means of a screw ring; P are pins
inserted in holes in the side of the flask when running in the plaster, to form
channels therein for the injection of the material into the cavities of the mould;
P', other pins, also inserted at the time of running in the plaster, to form vents for

page_text: the escape of the surplus material injected; Q are vent holes in the lower half of
the flask for the escape of surplus material when other dental bases are being
moulded in the same flask; R, pivoted covers for closing holes Q, Q, when the
excess of injected material begins to escape; S, screw plugs screwing into sockets
at opposite sides of the lower half of the mould, and each perforated to receive one
of the pins above referred to, the said plugs being removable for fixing the injector
cylinder J in their place.
The apparatus is used as follows:-The lower half of the flask is first filled
with plaster, in which are placed one or more wax patterns of dental plates, care
being taken that the points of the pins abut against the base. and centre of the
patterns, as shown in Figure 6. The top half of the flask is then placed upon the
lower one, and it is then also filled up with plaster over and around the patterns
placed in the lower half and the cover applied, and the two halves being locked
together the flask is placed in the press and clamped down by the screw E.
When the plaster is set sufficiently the two halves of the flask are separated, the
wax patterns are removed by means of boiling water, and the pins P, P¹, and
plugs S are withdrawn, leaving holes in the plaster for the injection and escape
of the material. The two halves of the flask are then again united and placed in
the press, the nozzle of the injector cylinder is screwed into the socket in place of
one of the plugs S, the flask is clamped down, and the spirit lamp is lighted for
the purpose of heating the flask. Either caoutchouc or celluloid is now placed in
the injector cylinder and slightly compressed by means of the screw plunger I.
When the flask and the injector cylinder, which is also heated, are raised to about
130° C., the plunger I is screwed slowly into the injector cylinder, thereby forcing
the caoutchouc or celluloid gradually and continuously into the cavity of the
mould. When the whole of the material contained in the injector cylinder J has been
forced into the mould, and the plunger has reached the bottom of the cylinder,
the material in excess will flow through the channels and out at the sides of the
lower half of the flask and the operation is terminated. The injector cylinder is
then unscrewed, and the flask while still hot is turned partly round in its seat, and
the injector cylinder is screwed into the other socket at the opposite side to that
to which it was before attached, and after being heated more caoutchouc or celluloid
is injected into the other cavity of the mould. Several dental plates may thus be
produced at once at a single moulding and heating operation in a single mould, and
the said plates may moreover be made of different materials, such as black or
colored caoutchouc, celluloid, &c., introduced either separately or together and
successively into the same cavity.
With this improved system of injector press and flask the preliminary heating
of the flask in the case of indiarubber is avoided, and the several subsequent
operations for finishing the moulded articles hitherto required are rendered
unnecessary, the articles being produced with perfect accuracy in every respect
and without liability of the teeth fastenings or plates becoming loose or deviating
from their proper position. Moreover, by the employment of the flask herein
described, the perfect union of new with old caoutchouc is obtained, and the use
of several different tools is rendered unnecessary for obliterating the traces of
junction or repair.
The above advantages are also obtained in the case of celluloid, as well as a
considerable saving in labor and material, more particularly in the case of small
plates, and in the repair of old plates and the addition of new teeth thereto.
Another advantage is that the apparatus may be used by unskilled operators.
Figures 11, 12, 13, and 14 respectively represent a part sectional elevation, plan,
cross section, and end view of an injector cylinder provided with a jacket or
chamber, extending its entire length to contain oil which is heated by the lamp.
The celluloid or caoutchouc cannot thus be overheated, as it is not exposed to the
direct heat of the lamp but receives the heat by transmission from the oil bath.
In operating the thermometer upon the injector should mark from 125° to
130° C, and that upon the flask 100° C.; under these conditions the operation

page_text: may be performed without any risk of burning the material. The injector cylinder
is screwed into the flask by hand, and to prevent it unscrewing when the plunger
is screwed back to withdraw it from the cylinder a steel bolt d is fitted to slide in
a dovetail groove on its top side, as shown in Figures 11, 12, and 14, which shoots
into a corresponding. groove in the socket of the flask to which the injector is
screwed, and thus prevents it from turning; c is a conical screw plug for closing
the cleaning orifice of oil jacket r; e, aperture for thermometer, which after the
completion of operation is closed by a screw plug to prevent escape of oil when
unscrewing the injector; f, air hole of oil jacket, also closed by a screw plug after
filling said chamber.
Having described the nature of the said Invention, and the manner of performing
the same, I declare that what I claim as the Invention to be protected by the
hereinbefore in part recited Letters Patent is,―
1st. In an apparatus for the manufacture of bases for artificial teeth of celluloid,
indiarubber, or other plastic material, the construction and arrangement of the
flask, made in two parts fitted together with a tongue and groove joint, and
arranged in such manner as to permit of producing articles of the same or different
colors or materials, substantially as shown and described.
2nd. The combination of the two parts constituting the flask, the lower part
having a loose bottom and a circular flange for the purpose specified, and the upper
part consisting of a cylindrical ring and loose cover with a central opening,
substantially as described and shown in Figures 4, 5, 6, 7.
3rd. The construction of the lower part of the flask with lateral orifices for
inserting the nozzle of the injector cylinder.
4th. In a press or apparatus of the kind described the combination of the
table B adapted to receive the circular flange upon the bottom of the flask, the
screw plunger I working in the cylinder J, the lamp N, the thermometer tube O
the covers R, and screw plug S.
5th. The combination with the press or apparatus, herein described, of the
injector cylinder represented in Figures 11 to 14, adapted to be screwed to the
flask, and provided with an oil jacket or chamber for heating it, and with orifices
c, e, f, and bolt d, as and for the purpose specified.
In witness whereof, I, the said Alexander Melville Clark, have hereunto set
my hand and seal, this Twentieth day of October, A.D. 1881.