Improvements in Electric Heating and Melting, specially Applicable to the Metal Pots of Linotype Machines and the like.
Year: 1898

page_text: Date of Application, 4th Feb., 1898
Complete Specification Left, 4th Nov., 1898-Accepted, 4th Apr., 1899
Improvements in Electric Heating and Melting, specially Applicable
to the Metal Pots of Linotype Machines and the like.
We, THE LINOTYPE COMPANY, LIMITED, of No. 188, Fleet Street, in the City
of London, Sole Owners of and Sole Manufacturers and Licensors under the
"Linotype" Patents, JoHN PLACE, Engineer, and MARK BARR, Electrician, both
of the Linotype" Works, Broadheath, in the County of Chester, do hereby
declare the nature of this invention to be as follows:-
The present invention relates to improvements in electric heating and melt-
ing. It is especially applicable to the metal pots of linotype machines for which
it has been developed, so that a description of the application of it to such a
machine, will best specify its nature. It consists in a novel combination with
the linotype machine, of a special dynamo electric machine and an electric
heater, and also in the combination with that heater and the metal pot, of an
improved device for regulating and maintaining the temperature of the molten
metal in the pot.
Hitherto, the metal pot of a linotype machine has been heated by gas or oil
burners. Neither they nor the fuel which they consumed, are organs of the
machine as such, and their action and effect has always left much to be
desired. The practical objects which we have had in view in developing the
present invention, have been
(1) Quicker melting of the type metal in the pot, than the gas or oil burners
hitherto used have been capable of effecting :
(2) Automatic regulation of the temperature of the molten metal and auto-
matie maintenance of that temperature constant, without extraneous moving
parts:
(3) Independence of outside sources of fuel to melt the metal and consequent
abolition of both pipes for supplying that fuel and of flues for the fumes from
the burners:
The source of electricity upon which our invention relies, is a dynamo machine
as distinguished from a so-called battery wet or dry. In carrying the inven-
tion into effect, the dynamo becomes an integral part of the machine as dis-
tinguished from one merely added to the frame thereof that one also capable of
being driven out of combination with it. In fact, the dynamo is built into the
machine and made an integral part of it, the object of such relationship being
to get the dynamo as near as possible to the metal pot itself.
The dynamo above mentioned is of a special type-it must yield a strong
current at a low voltage. The armatures form the stator portion of it. They
are built up of stamped sheets of soft iron. The field magnets consititute the
rotor portion and may be either of solid iron or steel, or laminated as the stator.
There, may be any desired number of poles. A suitable arrangement is a sub-.
divided magnetic circuit forming four poles.
There are two circuits, one the main or heating circuit, and the other intended
to excite the rotor.
:
The main circuit is of copper. of relatively large cross section and is wound'

page_text: round the armatures. The coils of the circuit. are of laminated copper. Each
stamping is U-shaped. They are assembled in groups of the same number and
at proper distances apart, with the ends of all the groups on one side of the
core opposite the ends of the groups on the other side, the connections between
the respective ends of the groups on either side being by means of laminated
bars of the same material and construction, serpentined to connect the said ends.
The several groups are held apart by proper insulations, and together, to form
a coil, by suitable cramping devices which are not passed through them.
The coils of the heating circuit are connected either in parallel or in. series
with one another, and by suitable terminals, in parallel or in series, with the
heating agent. This latter is a grid incorporated in any suitable way with the
metal pot and, preferably, as near the inner skin of it as possible.
The exciting circuit is of comparatively small sized copper wire. It is coiled
round the poles of the rotor and also round the armatures near the coils of the
main circuit, but in the opposite direction. Its armature coils are connected
either in parallel or in series with one another, depending upon the rapidity of
change of magnetism in the magnetic circuit through the stator and upon the
number of turns in the coils in relation to the voltage and current desired. The
same explanation applies to the coils of the main circuit.
on.
The exciting circuit includes a temperature regulating device described further
The coils of that circuit are connected in parallel or in series with the
said device, and in parallel or in series with the coils on the rotor through the
brushes and commutator. The coils on the rotor have a greater number of
series turns than the total series turns on the stator coils of the same circuit
about the armatures. The commutator and brushes are as heretofore both as
to construction and operation.
The regulating device above mentioned is preferably a grid. It is incorporated
with the pot in substantially the same way as the heating agent, but so as to
receive heat from the molten metal and share its temperature. Iron is pre-
ferred as its material because that metal exhibits a greater percentage change in
its specific electrical resistance for a given change in its temperature than any
other metal which could, under the circumstances, be used practically. The
device is fixed in a proper position for being heated by the molten metal.
Both the heating agent and the regulating device are electrically insulated
from the metal of the pot, by a very thin film or coating of any material which
has a maximum thermal conductivity with a minimum electrical conductivity.
The pot is packed outside with a comparatively thick packing of any material
which has a minimum conductivity, thermal as well as electrical. The above
described film and packing insure that the heat generated in the heating agent
and that communicated to the regulating device, shall not be lost outside.
The action of the invention is as follows. The motion of the rotor, by virtue
of its initial magnetism, subjects the stator to an alternating flux of magnetic
lines, which, extending through the stator coils of both circuits, generates
electro-motive forces therein, which increase until the electro-motive force in
the coils of the exciting circuit, is sending such a current through the magnétis-
ing coils of the rotor magnet that the desired and predetermined intensity of
magnetism is created in the latter.
The number of series of turns on the rotor magnet multiplied by the current
therein, must always be greater than the sum of the two products obtained by
multiplying the total turns respectively in series in the coils of the main and
exciting circuits by the respective currents in those coils. The object of the
proportion just described is to prevent excessive sparking at the brushes, and
that proportion is according to the requirements arising out of electro-magnetic
principles.
The windings on the rotor magnet and in the exciting coils on the armatures
are so proportioned that, with the resistance of the regulating device in circuit,
the potential difference between the brushes is that required to send the above

page_text: mentioned current through the coils on the rotor magnet. The electro-motive
force generated in the main coils is comparatively low but as the main circuit
has a low total resistance, a comparatively large current flows therein. The
resistance of the heating agent is, though actually of low value, very high in
comparison with the total resistance of the remainder of the main circuit.
Hence a large quantity of heat is generated per second in that agent, and is
absorbed by the type metal.
The regulating device being in close proximity to the molten metal, has the
same temperature or nearly so. As the electrical resistance of a body varies as
some power of its temperature, it follows that the current flowing through the
device will sink in value as the temperature of that device rises. Such rise
diminishes the strength of the magnetism in the rotor magnet and that
diminishing in turn causes the electro-motive forces generated in the main and
exciting coils to diminish. So that if the temperature of the metal rises beyond
a predetermined point, the current in the heating agent will diminish. In.
order that the regulation shall be of the proper scope and sensitiveness, the
rotor field must possess such magnetic permeability and proportions, that a
maximum instability of magnetic flux with regard to the magnetism current is
obtained.
An external resistance or a choke coil may be placed in the exciting circuit
for further regulation by hand for any given temperature required.
A switch, manual or automatic, is placed in the exciting circuit so that the
heating device may be put into or out of action as may be required.
Dated the 4th day of February 1898
PHILLIPS & LEIGH,
Agents for the Applicants.
Improvements in Electric Heating and Melting, specially Applicable
to the Metal Pots of Linotype Machines and the like.
"
We, THE LINOTYPE COMPANY, LIMITED, of No. 188, Fleet Street, in the City
of London, Sole Owners of and Sole Manufacturers under the Linotype
Patents, JoHN PLACE, Engineer, and MARK BARR, Electrician, both of the Lino-
type Works, Broadheath, in the County of Chester, do hereby declare the nature
of this invention and in what manner the same is to be performed, to be particu-
larly described and ascertained in and by the following statement:-
The present invention relates to improvements in electric heating and melting,
and is specially applicable to the metal pots of linotype machines for which
use it has been developed.
Hitherto, the metal pot of a linotype machine has been heated by gas or oil
burners. Neither they nor the fuel which they consumed, are organs of the
machine as such, and their action and effect have always left much to be
desired. The practical objects which we have had in view in developing the
present invention, have been
(1) Quicker melting of the type metal in the pot, than the gas or oil burners
hitherto used have been capable of effecting:
. (2) Automatic regulation of the temperature of the molten metal and auto-
matic maintenance of that temperature constant, without extraneous moving
parts; and
(3) Independence of outside sources of fuel to melt the metal and consequent
abolition of both pipes for supplying that fuel and of flues for the fumes from
the burners.

page_text: anying ngares which are
UC LARCH
specification and read therewith.
Figure 1 is a diagram illustrating the entire invention,
Figure 2 is a vertical section illustrating the embodiment of the electric
heater and the regulating device with the metal pot of a linotype machine,
Figures 3 and 4 are, respectively, a plan and a side elevation of a group of
Ushaped stampings,
1
Figure 5 is a perspective view of two poles and the relative part of the main
circuit coiled round it, and
Figure 6 is a detail end elevation of a main circuit coil.
It must be clearly understood that the application of the improved dynamo,
its improved main circuit coils and the improved heat regulating device to a
linotype machine, is no part of the invention itself, because the latter is equally
applicable to other machines and apparatus. It is only for convenience in
specifying the invention, that that particular application of it has been selected
for illustration and corresponding description.
The source of electricity upon which our invention relies, is a dynamo
machine as distinguished from a so-called battery wet or dry. In carrying the
invention into effect, the dynamo becomes an integral part of the machine as
distinguished from one that is merely added to the frame of the latter and from
one that is, moreover, so far from being an integral organ of it that it is capable
of being driven out of combination with it. In fact, the improved dynamo is
built into the machine and made an integral part of it, the object of such rela-
tionship being to get the dynamo as near as possible to the metal pot itself.
The position of the dynamo in the machine is not illustrated in the accom-
panying figures for the reason that that position is capable of so much variation
according to the form of the machine. It will suffice to say that the shaft V
of the rotor V26 is treated as one of the subsidiary shafts of the machine and
journalled and driven accordingly.
The first part of the invention consists in a novel type of dynamo. It must
yield a strong current at a low voltage. The armatures form the stator por-
tion 25 of it. They are built up of stamped sheets of soft iron. The field
magnets constitute the rotor portion 26 and may be either of solid iron or steel,
or laminated as is the stator V2. There may be any desired number of poles.
A suitable arrangement is a subdivided magnetic circuit forming four poles, as
illustrated in Figure 1.
There are two circuits, one the main or heating circuit V27, and the other V28
intended to excite the rotor V26.
The main circuit V27 is of copper, of relatively large cross section and is wound
round the armatures. That relatively large cross section is clearly illustrated
_ in Figure 1 and the necessity of coiling a conductor of such a section round
the armatures, necessitates a special construction of coils to make that coiling
practicable. This special construction forms the second part of the invention.
According to it, the coils are laminated and each stamping is U-shaped-see
Figures 3 and 5. These stampings are assembled in equal groups V29 -
Figures 5 and 6-and at proper distances apart, with the ends of the groups on
one side of the core opposite the ends of the groups on the other
side, the connections between the respective ends of the groups on
either side being by means of laminated bars V30 of the same material and con-
struction, serpentined to connect the said ends, one end of one group to the end
of the next group on the opposite side of the core. The several groups are held
apart by proper insulations Val, and together to form a coil, by suitable cramp-
ing devices which are not passed through them but surround them. With
reference to these cramps, it must be pointed out that the details of their con-
struction may be varied to any extent provided that no portion of them passes
through either the U shaped V29 or the serpentine V30 members of the coil. The
advantage of an outside cramp over bolts or the like device which must be passed

page_text: through all the ends of the said members previously punched to receive them.
is that there is no diminution of the cross section of the members nor any dis-
tortion of them, both of which diminution and distortion are more or less
inseparable from bolt holes in thin metal plates whether punched or drilled.
The coils of the heating circuit 27 are connected either in parallel or in series
with one another, and by suitable terminals, in parallel or in series, with the
heating agent. This latter is a grid V incorporated in any suitable way with
the metal pot V, and preferably as near the inner skin of it as possible.
The exciting circuit is of comparatively small sized copper wire. It is
coiled round the poles of the rotor V26 and also round the armatures near the
coils of the main circuit 27. There is no relationship between the directions
of the exciting circuit winding and the heating circuit winding, but the left
hand armature is wound in the opposite direction to the right hand armature.
as regards both heating and exciting coils. Its armature coils are connected
either in parallel or in series with one another, depending upon the rapidity of
change of magnetism in the magnetic circuit through the stator V and upon
the number of turns in the coils in relation to the voltage and current desired..
The same explanation applies to the coils of the main circuit V27.
The exciting circuit V8 includes a temperature regulating device V³
described farther on. The coils of that circuit V28 are connected in parallel.or
in series with the said device V and in parallel or in series with the coils on
the rotor V26 through the brushes and commutator. The coils on the rotor have
a greater number of series turns than the total series turns on the stator coils
of the same circuit about the armatures. The commutator and brushes are as
heretofore both as to construction and operation.
The third part of the invention consists in the improved heat regulating
device above mentioned. This is shewn in Figures 1 and 2 at V. It is pre-
ferably a grid. It is incorporated with the pot V in substantially the same
way as the heating agent V, but so as to receive heat from the molten metal
and share its temperature.. Iron is preferred as its material because that metal
exhibits a greater percentage change in its specific electrical resistance for a
given change in its temperature than any other metal which could, under the
circumstances, be used practically. The device V is fixed in a proper position
for being heated by the molten metal.
Both the heating agent V and the regulating device V are electrically in-
sulated from the metal of the pot V, by a very thin film or coating V35 of any
material which has a maximum thermal conductivity with a minimum electrical
conductivity. The pot V is packed outside with a comparatively thick pack-
ing V6 of any material which has a minimum conductivity, thermal as well as
electrical. The above described film and packing insure that the heat generated
in the heating agent V and that communicated to the regulating device V34
shall not be lost outside.
The action of the invention is as follows. The motion of the rotor V26 by virtue of
its initial magnetism, subjects the stator V25 to an alternating flux of magnetic lines,
which, extending through the stator coils of both circuits V, V, generates electro-
motive forces therein, which increase until the electro-motive force in the coils
of the exciting circuit V28, is sending such a current through the magnetising
coils of the rotor magnets that the desired and predetermined intensity of mag-
netism is created in the latter.
The number of series turns on the rotor magnets multiplied by the current
therein, must always be greater than the sum of the two products obtained by
multiplying the total turns respectively in series in the coils of the main and
exciting circuits V27 and V2, respectively, by the respective currents in those
coils. The object of the proportion just described is to prevent excessive spark-
ing at the brushes, and that proportion is according to the requirements arising
out of electro-magnetic principles.
The windings on the rotor magnets and in the exciting coils on the armatures

page_text: are so proportioned that, with the resistance of the regulating device V4 in cir-
cuit, the potential difference between the brushes is that required to send the
above mentioned current through the coils on the rotor magnets. The electro-
motive force generated in the main coils is comparatively low but as the main
circuit V27 has a low total resistance, a comparatively large current flows therein.
The resistance of the heating agent Vis, though actually of low value, very.
high in comparison with the total resistance of the remainder of the main
circuit. Hence a large quantity of heat is generated per second in the said
agent V33 and is absorbed by the type metal in the pot V.
The regulating device V being in close proximity to the molten metal, has
the same temperature or nearly so. As the electrical resistance of a body varies
as some power of its temperature, it follows that the current flowing through the
device will sink in value as the temperature of that device rises. Such rise
diminishes the strength of the magnetism in the rotor magnets; and that,
diminishing in turn, causes the electro-motive forces generated in the main and
exciting coils to diminish. So that if the temperature of the metal rises beyond
a predetermined point, the current in the heating agent V33 will diminish. In
order that the regulation shall be of the proper scope and sensitiveness, the rotor
field must possess such magnetic permeability and proportions, that a maximum
instability of magnetic flux with regard to the magnetism current, is obtained.
An external resistance V-see Figure 1-or. a choke coil V8 may be placed.
in the exciting circuit V2 for further regulation by hand, for any given tem-.
perature required.
SO
A switch V, manual or automatic, is placed in the exciting circuit V2,
that the heating agent V may be put into or out of action as may be required.
V40, V40 are the terminals of the heating agent V3, and V, V4; those of the
regulating device V4.
Having now particularly described and ascertained the nature of the said in-
vention and in what manner the same is to be performed, we declare that what we
claim is
1. In an electric heating or melting apparatus, the hereinbefore described
combination of armatures; main circuit; rotor magnets; and exciting and con-
trolling circuit.
2. The hereinbefore described combination in and with a conductor of large
cross section, of coils consisting of U shaped and serpentine members and sur-
rounding cramps.
3. In an electric heating or melting apparatus, the herein before described com-
bination with a heating agent forming part of the main circuit of a heat regulat-
ing device forming part of the circuit exciting the field magnets of the dynamo
and adapted to share the temperature of the material to be heated or melted,
as the case may be.
4. The herein before described combination of dynamo; heating circuit of
large cross section; heating agent forming part of that circuit; exciting and
controlling circuit; heat regulating device adapted by its position to share the
temperature of the material to be heated or melted, as the case may be, and by
being part of the exciting and controlling circuit to control the electro-motive
forces in the main circuit.
1000
CHAS. S. WOODROFFE,
No. 188, Fleet Street, London, E.C.,
Agent for the Applicants.