Improvements in and connected with Ovens for Baking or Heating Porcelain and other Substances for Dental and other Purposes.
Year: 1896

page_text: Date of Application, 10th Aug., 1896
Complète Specification Left, 6th May, 1897-Accepted, 12th June, 1897
PROVISIONAL SPECIFICATION.
Improvements in and connected with Ovens for Baking or
Heating Porcelain and other Substances for Dental and
other Purposes.
1, WILLIAM DALL, of 8 Newton Place, Glasgow, Surgeon Dentist, do hereby
declare the nature of this invention to be as follows:-
This invention relates to certain improvements in muffle ovens used for baking
or heating porcelain and other substances for dental and ether purpose.
In carrying out my invention I make the oven with preferably cylindrical casing
which is provided with a flame inlet at the bottom. The opening at the bottom is:
preferably made slightly out of the centre.
Fitted in the casing is a muffle which is preferably made of platinum although it:
may be made of other suitable material and is provided with projecting horns or
lugs which rest in the lining of the casing and support the muffle at the back.
The floor of the muffle may be made double and be capable of receiving a piece of
porcelain or other refractory material. Instead of having a double floor the
bottom of the muffle may have a pocket, or catches, or other arrangement for
holding the porcelain.
As it is very essential, in order to produce a proper combustion within the
casing, to admit air to its interior at or near to the flame I provide preferably,
below the muffle, an air admission device which may take the form of a valve,
plug, cock, grating or other equivalent and suitable arrangement. The air
admission device may be arranged in any suitable position at or near to the
muffle.
The casing with its muffle is enclosed within an outer metal casing consisting of
a cylindrical body which is surmounted by a conic cap or cover with holes therein
and which also fits into a solid metal base provided with an inlet opening slightly
out of centre.
Of course if the casing is not cylindrical the outer metal casing will not be
cylindrical but will be made to conform to the shape of the casing.
Dated this 8th day of August 1896.
H. D. FITZPATRICK,
Glasgow and London, Agent.
COMPLETE SPECIFICATION.
Improvements in and connected with Ovens for Baking or
Heating Porcelain and other Substances for Dental and
other Purposes.
I, WILLIAM DALL, of 8 Newton Place, Glasgow, Surgeon Dentist, 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:-
This invention relates to certain improvements in muffle ovens used for baking
or heating porcelain and other substances for dental and other purposes.

page_text: And in order that my said invention may be properly understood I have hereunto
appended an explanatory sheet of drawings, whereon,
Fig. 1 is a front elevation and Fig. 2 a vertical section of one form of the oven.
Fig. 3 is a front elevation and Fig. 4 a vertical section of a modified construction
of the oven.
Figs. 5, 6 and 7 are detail views.
Referring to the drawings whereon the same reference letters wherever repeatedl
indicate the same or similar parts.
In carrying out my invention, according to the arrangement shown at Figs. 1
and 2, I make the oven with a, preferably, cylindrical casing a which, as usual, is
lined with refractory material c. This casing is, or may be, made in two parts and
is provided with an opening for the gas or other burner (not shown). This
opening as shown is, by preference, made slightly out of centre.
Fitted in the casing a is a muffle d which is preferably made of platinum
although it may be made of any other suitable and well known material and which
is provided with one or more rearwardly projecting horns or lugs d² which fit into
recesses c¹ or rest upon ledges made in the lining c of the casing. These horns or
Jugs support the muffle at the back. As shown on the drawings the platinum
muffle is, as usual, made with corrugations d¹ at top and bottom for the purpose of
presenting a large surface to the flames and also for the purpose of giving it
additional stiffness and strength. It will further be seen that the muffle, as shown
in section at Fig. 2 and in plan at Fig. 7, has a round or somewhat round drum
shaped body with a narrow and upwardly inclined neck part e the open end of
which forms the mouth of the muffle. By having this peculiar form of neck the
muffle can be made with its floor at a lower level than the mouth so as to form a
pocket or sunk chamber for the reception of the articles being fired. The flames
from the burner can practically play all round the muffle and thus produce,
comparatively speaking, an equable heat in its interior. The neck e of the muffle
fits in the opening f of the casing.
Muffles constructed as herein before described are found to possess decided
advantages over those at present in use.
9 is a hinged or other cap provided for the opening f and this cap may be fitted
with a window g' made of mica or glass or the window may consist of a magnifying
lens which, if desired, can be coloured.
o is a small ledge or table arranged just below the cap 9.
The construction of oven shown is arranged to be heated by gas or gasolene
and for this purpose 1 prefer to employ one of my compound burners as described
in the Specification of my prior Patent No. 6128 of 1896. This burner is passed
up through the eccentric opening m¹ in the pedestal and the corresponding opening b
in the casing.
As it is very essential, in order to produce a proper combustion within the
casing, when using the Bunsen flame, to admit air to its interior at or near to the
flame of the burner I provide, preferably below the muffle as shown, an air
admission device which may take the form of a valve, cock, plug, grating or
other equivalent and suitable arrangement. The air admission device may be
arranged in any other suitable position at or near to the muffle. is the handle of
the cock and is a passage leading from the cock to the interior of the casing.
The device can be closed when using the blow pipe flame.
The casing a with its muffle is enclosed within an outer metal casing consisting
of a cylindrical body which is surmounted by a conic cap has at Figs. 1 and 2 or
a dome shaped cap as at Figs. 3 and 4. The cap may have holes in it if so desired.
The cylindrical body fits into the base or pedestal m as shown.
The cap ! is screwed to the casingh so that, when necessary, it can be taken off
and the upper part of the casing a removed.
The conical outlet or chimney
wire gauze or
at the top of the oven is or may be covered by
perforated plate p' secured in a removable ring p. pare pinching
screws for holding the ring in place.

page_text: Of course if the casing a is not cylindrical the outer casing / will not be cylindrical
but will be so made as to couform to the shape of the casing a.
The oven shown at Figs. 3 and 4 is practically the same as that at Figs. 1 an 1 2
with the exception that a cooling or a preliminary heating chamber is made at the
top of the casing a. In this modification the cylindrical part of the casing a is
made all in one piece and is provided with a flat cover or roof a' from which there
extends upwardly a central chimney . Secured, by preference removably, to the
metal roof, which is lined with refractory material, is a domed cover i having an
elongated doorway i capable of being covered by two sliding doors j,. A dome
shaped cap provided with a ring p and wire gauze p' encloses the cover i and
retains the sliding doors in place. The space around the chimney enclosed between
the roof a' and the dome cover i constitutes the cooling or preliminary heating
chamber.
The detail views Figs. 5 and 6 show, respectively, a plan and a front elevation
of the cover i. In Fig. 5 the doors j',, are removed so as to show the doorway j
and the slots k for guiding the projections made on the doors. Fig. 6 shows the
doors closed whilst the guide projections k¹ are indicated by dotted lines.
q are handles fitted to the doors, they may be made removable.
An opening r, corresponding to the doorway j is, of course, made in the
cover h¹.
Substances before being treated in the muffle can be heated up in the chamber
at the top of the oven whilst substances already treated can be placed therein to
cool gradually.
Instead of having the doors j', ja hinged or other door may be used for the
chamber i.
If it is so desired the muffle can be made with a simple flat floor and with a.
straight neck instead of an upwardly inclined one.
The gauze p can be dispensed with.
The structural details of the oven can obviously be further altered or modified
without departing from the invention.
Having now particularly described and ascertained the nature of my said inven-.
tion and in what manner the same is to be performed I declare that what I
consider novel and desire to claim is :---
1. The general arrangement and combination of parts of the oven for baking
or heating porcelain or other substances for dental or other purposes substan-.
tially as hereinbefore described and shown under modifications on the drawings
annexed.
2. A muffle made substantially as herein before described and shown on the
drawings annexed.
3. In muffle ovens for baking or heating porcelain or other substances for dental.
or other purposes, the application and use of an air admission device substantially
as and for the purpose set forth.
Dated this 28th day of April 1897
H. D. FITZPATRICK,
70 Wellington Street, Glasgow, Agent..