Improvements in Regulating Temperatures in Manufacturing Metals, and in Means or Apparatus employed therein.
Year: 1892

page_text: Date of Application, 12th July, 1892
Complete Specification Left, 12th May, 1893-Accepted, 1st July, 1893
PROVISIONAL SPECIFICATION.
Improvements in Regulating Temperatures in Manufacturing Metals,
and in Means or Apparatus employed therein.
1 ROOKES EVELYN BELL CROMPTON of Mansion House Buildings, Queen
Victoria Street, in the City of London, Engineer do hereby declare the nature of
this invention to be as follows:-
It is well known that certain operations in the working of malleable and ductile
metals such as rolling and wire drawing can be carried on with the greatest
advantage at certain temperatures which have been called critical temperatures.
In many cases this critical temperature lies within very narrow limits above or
below which limits the metal cannot be worked to the same advantage i.e. it is
liable to lose its mechanical strength and cohesion. Hitherto the obtaining of the
correct temperatures for the best working of such metals has been effected chiefly
by the personal skill of the workmen who attend to the furnaces or other means by
which the metal is raised to the required temperature. My improved methods
relate to the obtaining with greater certainty of these required temperatures by the
electrical means here after to be described. In order to effect this I sometimes
I
heat the metal by the passage of an electric current, in other cases
heat it
to a point somewhat below the required temperature by other means such as passing
it through a suitable furnace, but in order to obtain the final temperature desired on
its way to the rolling apparatus or the wire drawing apparatus, which I hereafter
call the rolls or the draw plates I pass a current of electricity through a portion of
the continuous length of metal whether it be sheet, strip or wire, the temperature
of which I desire to raise.
may
The current enters the metal at a contact or pair of contacts consisting of rollers
or rubbers and leaves it at a point further on which may be either the rolls them-
selves or the draw plate itself, or there may be a second contact or pair of contacts
at a point just short of the rolls or draw plate itself. I thus ensure that the metal
on its way to the rolls or the draw plate has its temperature raised by the passage
of a current of electricity through it, and I control the current of electricity and
hence the temperature finally attained by the metal by a system of electrical relays
which automatically regulate the current of electricity so as to maintain the
temperature constant within certain maximum and minimum limits. I do this by
mention
utilising several well-known thermo-electrical devices among others I may
a movable tongue or lever carrying contacts, such contacts completing an electrical
circuit to the right or to the left as the case may be according as the moving
tongue moves to the right or the left under the influence of the unequal expansion
or contraction of the dissimilar metals of which it is composed, the electrical relay
being so arranged that excess of heat beyond the maximum desired reduces the
supply of current and vice versa. I can also employ the direct expansion of mercury
to effect contacts and produce similar results. In some cases I enclose the space in
which the metal is so heated by a suitable covering which may be filled with steam
or non-oxidising gas so as to prevent loss by radiation, difficulties from external
draughts or currents of air and also losses of the metal by oxidation. I believe
my invention will be particularly useful in the rolling and wire drawing of metals
which only possess sufficient tensile strength for the purpose within very narrow
limits of critical temperatures. In cases often met with of rolling metals having
little mechanical cohesion I sometimes place two pairs of rollers very near to one
another and apply the heating process above described in the short length of metal
which intervenes between the two pairs of rollers and in some cases
gear these
rollers together in such a manner that the surface speed of the second pair of rollers

page_text: is rather greater than that of the first pair so as to exercise a constant compressive
action on the short length of the metal intervening between the two pairs, and I
can apply my above mentioned thermo-electrical relay in order to keep the
temperature of this portion sufficiently constant.
In some cases, when effecting the above objects, more especially when the masses
of metal to be dealt with are large I utilize my thermo-electrical relay to regulate
the supply of the other sources of heat such as for instance regulating the supply
of the air or air and gas to a gas furnace or the supply of air to a furnace
burning solid fuel, through which furnaces the metal passes on its way to the rollers
or draw plate.
Dated the 12th day of July 1892.
WM. BROOKES & SON,
55 & 56, Chancery Lane, London, Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Regulating Temperatures in Manufacturing Metals,
and in Means or Apparatus employed therein.
I ROOKES EVELYN BELL CROMPTON of Mansion House Buildings, Queen
Victoria Street in the City of London, Engineer 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 :-
It is well known that certain operations in the working of malleable and ductile
metals such as rolling and wire drawing can be carried on with the greatest
advantage at certain temperatures which have been called critical temperatures.
In many cases this critical temperature lies within very narrow limits above or
below which limits the metal cannot be worked to the same advantage i.e. it is
liable to lose its mechanical strength and cohesion.
Hitherto the obtaining of the correct temperatures for the best working of such
metals has been effected chiefly by the personal skill of the workmen who attend
to the furnaces or other means by which the metal is raised to the required
temperature. My improved methods relate to the obtaining with greater certainty
of these required temperatures by the electrical means hereafter to be described.
In order to effect this I sometimes heat the metal by the passage of an electric
current, in other cases I may heat it to a point somewhat below the required
temperature by other means such as passing it through a suitable furnace, but in
order to obtain the final temperature desired on its way to the rolling apparatus or
the wire drawing apparatus which I hereafter call the rolls or the draw plates I
pass a current of electricity through a portion of the continuous length of metal
whether it be sheet, strip, or wire, the temperature of which I desire to raise.
to
The current enters the metal strip or wire that is being worked at a contact or
pair of contacts consisting of rollers or rubbers and leaves it at a point further on
which may either be the rolls themselves or the draw plate of a wire drawing
system or there may be a second contact or pair of contacts just short of the rolls
or draw plate itself. I thus ensure that the metal on its way to the rolls or draw
plate should have its temperature raised by the passage of a current of electricity
through it and I supply this current from a generating source of sufficient
power
give sufficient excess of current to raise the metal to a point considerably higher than
the critical temperature desired so that by introducing resistances or by other means
of reducing this supply of current I can regulate it in such a manner that I control
the final temperature reached by that portion of the metal that lies between the
contacts above mentioned. I make this control automatic by placing in close
proximity to the heated part a thermo device which under the influence of
temperature will move so as to close contacts of electric relays and thus actuate
mechanism for increasing or reducing the supply of current which heats the metal.

page_text: Figure 1 shews one method of doing this here w is the wire or strip that is to be
heated to a fixed temperature passing through the rolls R, R, R', R, a current of
electricity produced by the dynamo or battery D B passes through the rolls as a
contact and through the wire or strip w heating the same; the regulation of the
current necessary to obtain the desired temperature is effected in this case by the
thermo couple T. C. which is also shewn in detail in Figure 2. This thermo couple
is composed of 2 wires P and P. R., one of platinum and the other made of an alloy
of platinum-rhodium. (I name this couple as a convenient one but several other
well known thermo couples can be used the principle being well known to electrical
engineers.) These two wires are autogenously soldered together at point a which
is placed as near as possible to the wire or strip w so as to avoid actual contact.
When this point a is heated it causes an E.M.F. in the thermo couple which is
used to actuate the regulating device as the E M.F. in the couple varies nearly as
the temperature applied to the point a; as the E.M.F. and consequent available
energy from this couple is feeble, a sensitive relay, Fig. 3, is used with it; this
consists of a needle n' attached to the deflecting coil of a magneto galvanometer of
the well known D'Arsonval type. This needle is in electrical connection by means
of a. b. with a mercury cup M. C into which is led a wire from the battery B,
the outer pole of this battery is made common to two electromagnets 1 and 2;
P and P are the adjustable pins in electrical connection with 1 and
tively, the coil C. W. is deflected by the passage of a current due to the heating
of the junction a Figure 2. When the requisite heat is obtained in the wire w the
pins Pi and P' are set on either side of the needle at distance equivalent to the
maximum amount of variation in temperature allowed; it follows that any diminution
or increase of heat beyond this allowed maximum variation by increasing or
diminishing the E.M.F. and consequently the current flowing through the coil
will increase or diminish the deflection in a corresponding manner and will bring
the needle n into contact with either P₁ or P2 which will thus allow either of the
electro magnets 1 or 2 to become energised; the energising of either of these
magnets may be used as the means of actuating any device for the regulation of the
current flowing in the wire w Figure 1 either increasing or diminishing its
amount.
respec-
In place of the thermo couple T. C. the ordinary form of thermostat shewn on
Figure 4 may be used; it consists of a compound bar CB of metals having
dissimilar coefficients of heat expansion. These bars being secured back to back,
any increase of temperature causes the compound bar or tongue to curve; s
and are adjustable set screws so that any alteration of curvature of the bar
which is fixed at the point will bring either set screw into electrical contact
with C. B. which as is shewn in the drawing may as in the case of the thermo
couple device bring either of the electro-magnets E M into action. We sometimes
use a thermo balance shewn at Figure 5, here this consists of two glass bulbs T. B.
connected together with a glass tube G. T, this latter and a portion of the bulb is
filled with mercury and hermetically sealed by means of the clip c the whole
combination is pivotted at P; one of the bulbs T is placed adjacent to the heated
wire or strip w, the heat radiating from this causes the air in the bulb to expand
and forces the mercury back into the bulb B and therefore upsets the equilibrium
of the apparatus; by adjusting the clip C so that the equilibrium is maintained at
the critical temperature any deviation from that temperature will cause the balance
to sway either way so allowing either of the contacts c and c¹ to come into contact
with mercury cups or springs M. C so as to energise either of the electro-
magnets E. M as before.
In Figure 6 I show another arrangement consisting of a thermometer tube T
into which is fixed three platinum contact pins PP2 P3; P¹ being maximum
temperature, P being minimum temperature allowed, P³ in connection with the
battery B; at the critical temperature the surface of the mercury in the tube lies
between the points P' and P2, at this temperature the connection is made with P1
which being in connection with the electro-magnets E. M. energises it and causes

page_text: the armature A to be attracted and held. If owing to reduction of temperature
the mercury falls below P' the armature springs back into the position shown on the
drawing and allows M to be energised; on the other hand after rising to P',
E becomes energised as before.
In the arrangement shown in Figure 7 the wire or strip w actually passes through
or lies adjacent to a spiral of wire s. p one of its ends being fixed at F the other
end being free, two adjustable stops s¹ and s are so fixed that any variation at the
end of the spiral due to elongation or contraction from rise or fall of temperature
displaces the further end of the spiral longitudinally or it can be arranged that the
displacement is magnified by being made circumferential in direction. Whichever
method is employed this displacement of the further end of the spiral is arranged
to bring it into contact with contact terminals as before and so to alternately
energise the magnets E M as before.
In the arrangement shown in Figure 8 the wire or strip w has adjacent to it a
plain strip A B formed of a metal having a high co-efficient of heat expansion,
the further end of which makes contact with two terminals energising the
magnets E. M respectively according to its position. This very simple arrangement
can be used in certain circumstances where great delicacy is not required and where
simplicity of construction is of great importance.
As it is evident that with any of these arrangements the maintaining of the
temperature at the critical point with great accuracy would be greatly influenced by
external currents of air, with all or any one of these arrangements, I can combine
a casing or covering to protect the heated portion of the strip or wire wo from
the cooling action of convection currents of air. In some cases I go further than
this and arrange to make this casing sufficiently air or gas tight that I can fill it
with a non-oxidising gas or vapour, the object of this arrangement being to protect
the surface of the strip from oxidation.
I have not thought it necessary to confuse the drawings by showing this arrange-
ment on the drawing, but its construction will be readily understood by anyone
accustomed to this class of mechanism. When I explain that the covering will in
most cases consist of a tube through which the strip or wire w passes and into
which is introduced the thermo couple, expansion strips or other arrangements
hereinbefore described; the strip or wire w passes in and out of this casing
through stuffing boxes or glands and the electrical connections necessary can of
course be made through insulating the air tight terminals. In some cases where
the wire or strip is of considerable cross section (so that the cost of heating it up
from the temperature of the air to the critical temperature required would be very
considerable, if the whole of the heating were carried out by nieans of the electrical
current) I pass the strip through a suitably arranged furnace on its way to the
rollers and in some cases I can thus arrange that it requires a fixed temperature
without the use of any special regulating appliances, such for instance as passing
through a bath of oil, a bath of melted metal or even a sand bath, but in other
cases where I desire to carry out this first portion of the heating to a considerable
temperature I can combine with the gas furnace any one of the devices before
alluded to, the electrical regulating appliance being placed in such a position that
it is affected only by the heat of the strip and not by the heat radiated from the
heating appliance itself.
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
claim is;
In regulating temperatures in manufacturing metals and means or apparatus
employed therein :-
1. The method of raising metals to a desired critical temperature and main-
taining the same by passing an electrical current through them and regulating the
supply of the electric current by an automatic thermo device, substantially as
hereinbefore described and shewn,

page_text: 2. The arrangement or combination and use of means for maintaining a critical
temperature in a wire or strip substantially as herein described and shewn with
reference to Figure 1.
3. The arrangement or combination and use of means for maintaining a critical
temperature in a wire or strip substantially as described and shewn with reference to
Figure 2.
4. The arrangement or combination and use of means for maintaining a critical
temperature in a wire or strip substantially as described and shewn with reference
to Figure 3.
5. The arrangement or combination and use of means for maintaining a critical
temperature in a wire or strip substantially as described and shewn with reference
to Figure 4.
6. The arrangement or combination and use of means for maintaining a critical
temperature in a wire or strip substantially as described and shewn with reference
to Figure 5.
7. The arrangement or combination and use of means for maintaining a critical
temperature in a wire or strip substantially as described and shewn with reference
to Figure 6.
8. The arrangement or combination and use of means for maintaining a critical
temperature in a wire or strip substantially as described and shewn with reference
to Figure 7.
9. The arrangement or combination and use of means for maintaining a critical
temperature in a wire or strip substantially as described and shewn with reference
to Figure 8.
10. The arrangement or combination and use with any of the above described
combinations or arrangements of parts of a covering or casing to prevent the
influence of convection currents of air, substantially as and for the purpose herein-
before set forth.
11. The arrangement and use of any one or more of the above controlling
devices for regulating the temperature for working of the metal in combination
with a heating furnace for primarily heating the metal, substantially in manner
and for the purpose set forth.
Dated the 11th 1M
1000
WM. BROOKES & SON,
55 & 56, Chancery Lane, London, Agents for the Applicant.