Improvements in Means to be employed in connection with the Electrical Heating of Metals for Various Operations.
Year: 1894

page_text: Date of Application, 15th Nov., 1894
Complete Specification Left, 11th July, 1895-Accepted, 17th Aug., 1895
PROVISIONAL SPECIFICATION.
Improvements in Means to be employed in connection with the
Electrical Heating of Metals for Various Operations.
I, WILLIAM HOLLAND the younger of Cox Brothers and Holland Limited, of
Greet, near the City of Birmingham, Manufacturer, do hereby declare the nature
of this invention to be as follows:-
My invention relates to improvements in means to be employed in connection
with the electrical heating of metals for the processes of hardening and subsequent
tempering, also for tempering metals direct, and for the working of metals, and is
an improvement upon former Letters Patent granted to me and bearing date the
14th day of March 1888 No. 3963.
The object of my invention is to impart to a length of metal, or to a metallic
object, a uniform temperature or heat.
According to my invention, a metallic length requiring to be electrically heated
and to be equalized in temperature is first passed through guide rollers, and then
drawn into and through an insulated metallic tube, and brought into close and
intimate contact with the inside walls of it, so that the electrical current is made to
take a short or new circuit through the said tube, which takes up any excess or
redundant heat generated in the length, in virtue of diminished cross sections at
parts.
Thus, where diminished cross sections occur, the heat evolved is greater than in
the other parts, consequent upon increased resistance, and as the heated metallic
length is in direct contact with the equalizing metal tube, the excess or super-
abundant heat occurring at such diminished cross sectioned parts is absorbed or
taken up by the said tube by conduction, and is then uniformly re-distributed by
re-conduction back again to the heated wire.
It is obvious that if electrically and unequally heated metal was brought into
contact with a hardening medium. such as oil, unequal hardening will occur,
consequent upon the physical constitution of the article or length varying at
points.
The return circuit is made by a spring contact pressing upon the metallic length,
rearward of the equalizing tube, and in order to prevent too large a current being
passed through the article under treatment at the start, a series of resistance coils
are inserted in the main circuit.
The reason for the insertion of resistance coils is that the resistance offered
by the wire to the passage of the current is greater when it is hot than when it
is cold.
Instead of employing a tube as the equalizing means, its equivalent, in the form
of a plate, rod, strip or other metallic body, may be employed.
The length of equally heated metal, if requiring to be hardened, is then passed
through an oil tank, and if necessary, is subsequently tempered by passing it
through an electrically or otherwise heated tube. If the metal requires to be
heated only for the purpose of working, then it is operated upon when in a soft
state by tools, pressure and the like.
Dated this 14th day of November 1894.

page_text: Improvements in Means to be employed in connection with the
Electrical Heating of Metals for Various Operations.
I, WILLIAM HOLLAND the younger of Cox Brothers and Holland Limited, of
Greet, near the City of Birmingham, Manufacturer, 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 :-
My invention relates to a method of, and to appliances to be employed in
connection with, heating metal lengths electrically prior to the same being
hardened, tempered or worked, and has for its object, the equalization of the
temperature throughout the whole length of the article under treatment.
It is understood that the distribution of the heat depends upon the distribution
of the resistance to the passage of the electric current through the object to be
heated and that so long as a length of metal is of the same diameter and material
throughout, the resistance to the current will be the same in all parts, and the
heating will be uniform, but if the area comprehended by the cross section should
vary, or the physical character of its homogeneity be unequal, then the resistance
will concentrate itself at points or spots along the length being heated, and to
obviate this concentration and unequal heating is the aim of my invention.
Figure of the accompanying drawing represents my invention in operation for
equalizing the temperature of electrically heated trough-sectioned lengths of wire
prior to the same being hardened.
Figure 2 represents, upon an enlarged scale, a longitudinal vertical section of the
equalizer part of my apparatus separately and showing a length of metal in direct
contact with the inside walls of the same, so that electric current passing through
the article being beated becomes short-circuited through the medium of the
equalizer.
Figure 3 represents a cross section of Figure 2 upon the dotted lines .r-x.
Figure 4 represents upon an enlarged scale, a short length of the trough-
sectioned wire under treatment, and also a cross section of the same.
Figure 5 represents a cross section of a modified form of equalizer.
The same letters of reference indicate corresponding parts of the several figures
of the drawing.
a is a metal length or wire (which may be of any cross section) passing through,
and coming into direct contact with the inside walls of, the bore of an open-ended
metallic tube b. exteriorly surrounded by insulating material e, which may be
asbestos, mica or the like, which tube constitutes the equalizer, and is supported
upon a table or rest d.
The metallic length a, under treatment has its after part a', supported
through an insulated roller guide or carrier e, which has connected with it, an
electrical circuit wire 7. The fore part a², of the metallic length under beating
has pressing upon it, a spring contact g, being connected with a circuit wire f¹.
h is a valve, fitted at the near side end of the hardening tanki, which is filled with
blubber or other oil, and is located within a water tank i', to keep the same cool,
and is also provided with a vane or agitator j, driven by a band j', through the
medium of a pulley 2, receiving its motion from a band j³.
The oil adjacent to the valve and the heated in-coming wire is circulated and
kept cool by the fan, vane or agitator.
Assuming the length of wire to be heated is being fed forward, and that the
electric heating current enters the wire f, which has in its circuit, a resistance coil,
to prevent over-heating on starting, it then passes to the guide rollers and is
conveyed, by contact, to the metallic length under heating treatment, which becomes

page_text: considerably heated during its passage from the point of contact to the mouth of
the equalizer, when a major part of the electric current takes a short circuit
through the metallic tube with which the wire under treatment is in direct and
continuous contact throughout its whole length, and the heating is equalized, or
the temperature is made uniform throughout the whole of the length in the tube
and after the wire emerges from or leaves the said metallic tube, and during its
passage from thence to the spring contact, the whole of the current re-enters the
wire, which is again uniformally heated and the temperature is enhanced to the
required degree, when it then enters the oil in the oil tank through the valve, and
is then hardened.
The operation of tempering the length differs in no essential respect from the
process of hardening, other than that the electrical energy is applied as a softening
agent instead of for hardening.
In heating metals for softening them prior to the rolling or fabricating the
operation is alike to that already described with respect to hardening and
tempering.
Instead of employing an open-ended and insulated equalizer tube, I may employ
an open-ended trough-shaped equalizer, such as represented in Figure 5. But I
wish it to be understood that instead of employing a tube or trough-sectioned
equalizer, I may employ any insulated and thick metallic length, adapted to short
circuit the current and offer less resistance to its passage than the wire being
treated, which may be drawn as well in intimate contact with the outside surface
of the equalizer as through an inside part of it.
It will be further understood that the equalization of the temperature of the
article under treatment is owing to the excessive heat at varying points of the
length being abducted or abstracted therefrom by the equalizer, with which it
comes into contact, and which is only an insulated metallic body of greater
proportions or bulk than the said article under heating treatment.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what I
claim is:
First. Equalizing the temperature of metallic lengths heated electrically, by
making the said lengths come, in their traverse, into direct contact with an insulated
metallic tube or length, substantially as described and set forth.
Secondly. The process of equalizing the temperature of metallic lengths heated
electrically by the appliances and in the ways substantially as described and set
forth.
Dated this 10th day of July 1895.
WILLIAM HOLLAND, JUNIOR,
By Henry Skerrett,
24 Temple Row, Birmingham, Agent for Applicant.