Improvements in Method and Apparatus for Electrical Hardening and Tempering.
Year: 1891

page_text: Date of Application, 26th May, 1891-Accepted, 25th July, 1891
COMPLETE SPECIFICATION.
Improvements in Method and Apparatus for Electrical Hardening
and Tempering.
A communication from ELIAS ELKAN RIES, of Baltimore, in the State of
Maryland, United States of America, Electrician.
I, ALFRED JULIUS BOULT of 323 High Holborn in the County of Middlesex,
M.I.M.E., 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 has reference to improvements in the method of and apparatus
for hardening and tempering articles of steel and iron by the aid of electricity and
its main object is to facilitate that process generally and to attain greater certainty
and uniformity of result.
As heretofore practised the steel or iron article to be hardened and tempered was
generally heated to the desired degree in an open furnace with free admission of
air; the article was then transferred as rapidly as possible from the furnace to the
chilling bath, and after removal from the latter was again heated in the furnace to
give it the required temper. When this is obtained the re-heated article is some-
times again plunged into a cooling bath. This process is very inconvenient, and
the results obtained are not uniform under apparently the same conditions.
In the first place the heating in a furnace is a very slow process, and the long
exposure of the steel or iron to the atmosphere while being heated, produces a
remarkably thick layer of oxide upon the surface, which layer, when the article is
chilled, peels off in scales whereby the surface becomes rough and requires additional
dressing. The heavier the article operated upon is, the more this defect becomes
apparent, and this is especially true in low grades of steel and in iron, which must
be heated to a higher temperature to give them the desired degree of hardness.
In the second place other things being equal, the hardness of the article depends
largely if not entirely, upon the degree of incandescence which it has at the
instant it is received in the chilling bath and the operator must judge of that in
every instance separately and he must take into account the loss of incandescence
Where
which takes place during the transfer from the furnace to the chilling bath.
the steel or iron is thin, as in knife- or saw-blades, the loss of incandescence during
the transfer is considerable, and in order that the article may be in proper con-
dition when immersed into the bath it must be heated in the furnace to a higher
degree than is actually necessary, which is very objectionable, more especially
when high grade steel is operated upon.
Thus it happens that when a great number of like articles are hardened and
tempered in succession, no two of them will have the same hardness or temper.
All these imperfections are obviated by this improved process, wherein the article
to be hardened is heated very rapidly by the passage through the same of a
suitable current of electricity which will raise the same to a certain accurately
adjustable degree of incandescence, and will maintain it in that condition until the
instant of immersion into the chilling bath.
Having determined the conditions under which a certain article is raised to the
required temperature any desired number of like articles may successively be
operated upon with exactly the same result, and thus the uniformity of hardness
of discrete but like objects, which in the manufacture upon a large scale is very
desirable, may be secured.
The same uniformity of hardness and temper is also secured by this process
throughout the whole length of a band, web or rod of steel and iron, by passing the
heating current through continuously advancing contiguous sections of the band or

page_text: web which are chilled in uninterrupted succession as soon as they have attained the
degree of incandescence determined upon.
All this will more fully appear from the following detailed description in which
reference is made to the accompanying drawing illustrating some convenient
apparatus which may be used in practising the improved process. It will however
be understood that this invention is not dependent upon the use of any particular
apparatus since the same may be practised without the aid of any organized
machine or apparatus or with machines or apparatus entirely different from those
which for the sole sake of clearness and convenience of description, are hereinafter
.-referred to.
In these drawings I have shown in:
Fig. 1a perspective view of an apparatus which may be used for hardening and
tempering a number of discrete but like articles; in
Fig. 2 a plan view of a portion of the clamp-frame shown in Fig. 1 ;
Fig. 3 is a view of a section on line y y Fig. 2; and
Fig. 4 is a perspective view of a spacing-block employed in this apparatus:
Fig. 5 is an elevation of an apparatus for practising the invention on bands, webs
of saws, wires or rods of great length, with the electrical connections and circuits
represented mainly in diagram;
Fig. 6 is a plan of the same apparatus with the electrical circuits omitted;
Fig. 7 is a sectional view of the chilling-block used in this apparatus the section
being taken on line a Fig. 6:
Fig. 8 is a like view the section being taken on line y' y' Fig. 6:
Fig. 9 is a plan view of another form of the apparatus in which contact rollers
are used in place of brushes;
Fig. 10 is a detail plan view of a portion of a set of contact rollers;
Fig. 11 a view partly in elevation of a section on line y y Fig. 10;
Fig. 12 an elevation partly in section of the cooling trough employed in the
apparatus shown in Fig. 9;
Fig. 13 a section on line
Fig. 12;
Fig. 14 represents a view of a section on line a
Fig. 15 a view of a section on line
Fig. 5.
Fig. 5; and
Like numerals of reference refer to the same or like parts throughout the
drawings.
For carrying the process into effect upon steel or iron articles of limited length
the apparatus illustrated in Figs. 1 to 4 may be employed.
Upon a suitable base 1 of insulating material is mounted a rectangular tank 2
which contains the chilling fluid such as water or oil; and four vertical guide-
posts 3, 3, 3, 3 of metal, rising from the base 1, two on each end of the tank, are
connected with a suitable source of electricity (not shown) by wires 4, 5 which are
clamped to the guide-posts by binding screws 6, 6.
A rectangular frame 7 composed of two metallic end bars 8, 8 and two side-
bars 9, 9 of insulating material is guided between the posts 3 by metal
brackets 10, 10, 10, 10 of which two extend from each end bar of the frame.
These brackets rise from the upper surfaces of the end-bars and curve outwardly:
they are perforated vertically at 11 near their free ends as shown, and the guide-
posts are received in these perforations, so that the whole frame may be moved up
and down upon the guide posts by means of suitably shaped handles 12, 12 fixed to
the side bars of the frame. The handles 12, 12 may be of metal and will then be
insulated from the frame or they may be made of insulating material.
Each end bar 8 has formed a short recess 13 at one end on the inner side and has
in the remaining projecting portion a dove-tail groove 14. A number of metallic
spacing-blocks 15 are provided for use with this frame and these blocks are cach
formed with a dove-tail tongue 16 which fits into the groove 14. Each block is of
such width that it may be inserted into the recess 13 after which its tongue will
engage the groove in the end bar and the block may then be moved along the end
bar to any position upon the same.

page_text: Near each end of one of the side bars 9 is fitted a clamp-screw 17 which passes
through the side bars and bears against the spacing-blocks inserted into the adjacent
end bar. In this manner, any number of articles to be hardened and tempered
may be clamped within the frame 7 with spacing blocks between the same as will
be readily understood. In the drawings I have shown a number of steel or iron
laminac 18, 18 with spacing blocks between the same; these laminae may be knife-
or cutter-blades, springs or any other suitable article of manufacture and in Fig.
such laminae is shown as a saw-blade.
The leading wires 4, 5 are supposed to be connected with the poles of a suitable
source of electricity which furnishes a current of low tension and great quantity;
such currents are technically known as heating currents," and may be derived
either directly from a dynamo generator or from the secondary coil of an induction
transformer or from a secondary battery. The invention however is not limited to
the use of either of these sources of electricity, since the heating current may also
be obtained from a primary battery or from any other generator of low tension
currents. A rheostat 19 of any ordinary or improved construction included in one
of the leading wires 5 is used both for closing and opening the circuit and for
regulating the current; this is done by proper manipulation of the switch-lever 20
as is well understood by those skilled in the art.
With the apparatus so far described, articles of steel or iron of a certain definite
length are hardened and tempered in the following manner;-
The clamp frame 7 is raised to the position shown in Fig. 1 by means of the
handles 12, 12 and is fixed in that position by the binding screw 21; then one
spacing block 15 is inserted at each end of the frame in the manner hercinbefore
described and is moved within the dove-tail groove 14 until it abuts against the side
bar 9 at the rear of the frame. The bar, rod, blade or other article 18 to be
hardened and tempered is then placed in the frame against the pair of spacing
blocks just inserted and another pair of such blocks followed by another specimen
of a like article 18 is then placed in position and so forth until the frame is filled;
a pair of spacing blocks being placed against the last article 18 of the series. The
clamp screws 17, 17 are then operated to force the spacing blocks and the blades
or other articles between the same together, and it will now be understood, that the
blades 18 are in multiple are branches of the circuit of which the leading wires 4,5
and the compound switch and rheostat form a part.
The charging of the frame 7 is done while the circuit is open at the rheostat, the
switch-lever 20 being for this purpose turned upon the idle contact plate 22 at the
right-hand end of the rheostat. For greater convenience the frame 7 may be
entirely removed from the posts 3, 3 for the insertion of the articles to be operated
upon.
The frame being properly charged the switch-arm 20 is slowly moved toward the
terminal contact plate 23 to close the circuit and to cut out resistances until the
blades 18 have attained the desired degree of incandescence. Supposing now it is
found that this incandescence is attained when the switch-arm is in the position
shown in Fig. 1, the operator will know that the same degree of incandescence will.
be produced in all subsequent charges of the frame with like blades or articles 18.
Consequently in hardening and tempering a large number of like objects
consecutively, the switch need only be moved to the same position to insure the
same degree of incandescence and therefore other things being equal, the same
hardness and temper in all blades or other objects by the subsequent chilling.
While the current is thus maintaining the steel or iron articles at the proper degree
of incandescence, the binding screw 21 is loosened and the frame is allowed to
descend into the chilling fluid in the tank 2, and at the instant when the lower edges
of the blades 18, come into contact with the chilling fluid the circuit is suddenly
opened by turning the switch-lever upon the idle contact plate 22.
In this manner
the cooling of the heated articles by radiation before the instant of immersion
into the chilling fluid, is avoided.

page_text: This can be still better avoided by breaking the heating circuit automatically at
the instant of immersion in any desired manner. For this purpose I have shown in
the drawings (Fig. 1) an insulating sleeve 3' upon each guide-post 3 but flush with the
surfaces of the same. These insulating sleeves are so located that when the frame 7
descends and at the instant when the lower edge of the blades or other articles 18
touch the chilling fluid the brackets 10, 10 will just have passed beyond metallic
contact with the guide-posts and thus the circuit will be automatically broken;
after which the switch-lever 20 will be turned upon the idle contact plate 22. To
insure the immersion at the moment of the breaking of the circuit, the level of the
chilling fluid is adjusted by pouring more or less of it into the tank.
An adjustable stop sleeve 3" upon one or more of the guide-posts is used for
controlling the depth of immersion.
Other means for breaking the circuit automatically at the instant of immersion
may be used but the arrangement shown is quite effective and insures uniformity of
result in successive operations.
In this process any of the well known chilling fluids may be employed; if oil be
used the articles operated upon will ordinarily have received both their proper
hardness and temper after immersion, but if water be employed the articles will
ordinarily be too hard and too brittle, and they must be again slightly heated to
receive the required temper. This is done electrically by raising the frame out of
the tank and closing the circuit again for a short time with a much greater resistance
included than before, but this resistance once ascertained for a given article will be
the same in all subsequent operations upon like articles whereby great uniformity
of results is obtained.
When only the edge of the article subjected to the process is chilled as is some-
times the case with saw-blades, the subsequent tempering is effected in the ordinary
manner z. by allowing the chilled portion to become gradually heated by the
unchilled portions which are ordinarily hot enough for this purpose, and when the
proper temper is reached as is indicated by the colour assumed by the chilled
portion the whole article is immersed in the chilling fluid whereby the tempering is
arrested at any desired stage.
It will be clear that in practising this process my correspondent is not absolutely
confined to the use of the identical apparatus so far described since any other devices
and notably those in common use in electrical manipulations may be used with
advantage; thus it is not necessary that a number of articles be subject to the
process at the same time and that a frame of the character described be used, for a
single blade may be hardened and tempered by this process in which case any
ordinary electrical contact plate at the terminals of the leading wires 4, 5 will be
secured to the ends of the blade, or these wire terminals may themselves serve as
contacts. In fact no definitely organized apparatus need be used so long as the
steps taken are in accordance with the principles herein before explained.
If a band, web, rod or wire of great length is to be hardened and tempered by
this process the apparatus shown in Figs. 5, 6, 7 and 8 may be employed with
advantage.
Upon a table 24 are shown sets of rollers 25 between which the article 26 operated
upon is continuously fed in the direction indicated by an arrow these rollers may
be simple feed-rollers taking the web 26 from a machine by which it is trimmed or
dressed or otherwise prepared for use or they may be the terminal rollers of a
rolling mill in which the web or blade is shaped from ingots or bars. Adjoining the
table 24 is a bench 27 upon which are mounted two sets 28, 29 of contact brushes
mounted in clamps 30, 31 provided with downwardly projecting lugs or tails 301 31.
These clamps are either insulated from the bench or the latter is made of insulating
material such as slate or marble and the clamps with their brushes are adjustable
toward and from each other by a right and left hand screw 32 passing through the
lugs 30 31 and constructed with a piece of insulating material 33 interposed
between the right and the left hand portions as shown.

page_text: Between the set 28 of contacts and the feed-rollers 25 25 are placed one or more
pairs of scouring rollers or brushes 34 which act upon the sides of the band 26 to
remove spots of rust, oil or other insulating impurities which may adhere to the
same. Behind the set 29 of contacts and also mounted upon the bench is a support 35
through the downwardly projecting lug or tail 351 of which that part of the right
and left hand screw 32 passes which also passes through lug 31' of the clamp 31, so
that the support. 35 is adjusted with clamp 31 but always remains at the same
distance from the same. Upon this support 35 is mounted so as to slide upon the
same a chilling block 36 36 the construction of which is indicated in the drawing
with sufficient clearness for the purposes of this case, the same structure is illustrated
and described with great minuteness of detail with reference to Figs. 7 and 8.
It is now sufficient to know that the chilling block is in the main U-shaped the
two legs or branches of which are marked 36 and 36' respectively in Figs. 6 and 7
and a pair of chilling jaws 37 37 are removably inserted between the legs of the U
and bear upon the web or other article 26 which is fed between the same. In' the
body of the chilling block are formed communicating channels 38 to the openings
of which pipes or tubes 39 are fixed, through which a suitable cooling agent is
carried to and from the chilling block whereby the latter and the jaws 37 are main-
tained at a desired low temperature. An independent adjusting screw 32 passing
through a lug 115 projecting from the chilling block and journalled in support 35
as shown in Fig. 7 permits of adjusting the chilling block with reference to the
set 29 of contact brushes.
The two sets 28 29 of contact brushes are connected in the circuit 40 of the thick
wire secondary coil of an induction transformer 41 by the leading wires 42, 42, the
fine wire primary coil of said transformer is connected to the primary source of
current by the wires 43, 43 in the circuit of which is also included a current
regulator 44 of any ordinary or improved construction.
The process as practised by means of this apparatus is as follows;-
The object operated upon is fed by the feed-rollers 25, 25 between the scouring
brushes 34, 34 by which the insulating impurities which may adhere to the same
are removed. The article then passes between the two sets 28, 29 of contacts and
is there heated to any desired degree of redness by the passage of the heating
current through the same. The degree of incandescece is regulated by the current
regulator 44 by the speed of the feeding motion and by the distance of the two sets
of contact brushes from each other, but if these elements are once adjusted for any
portion of the article operated upon, the degree of incandescence attained will be
the same for all successive portions. The chilling block is adjusted as close as
practicable to the last set 29 of the contacts and from the latter the article is
continuously transferred to and between the chilling jaws 37, 37 from which it
emerges properly hardened and may then be considered a finished article of manu-
facture. This is more especially the case with blades or bands of iron or low grades
of steel, but for the higher grades of steel an auxiliary heating of the chilled article
is required in order to give to the same the required temper.
This may be accomplished by passing the article between two auxiliary sets 281, 29¹
of contact brushes which constitute the terminals of a circuit 40' 40' derived from
the main heating circuit 40, 40 and in which a rheostat 19' is included for controlling
the current passed through the auxiliary contacts and through the article. The
auxiliary brushes are adjusted by a screw 321 upon a bench 27 in all respects
similar to the like parts for the sets 28, 29 of contact brushes.
For such articles which are ordinarily hardened at one edge only as in the case
of cutter- or saw-blades the auxiliary heating or tempering is effected in a different
inanner. The chilling jaws are in that case formed to embrace and bear upon a
portion of the article only which includes the edge of the same as shown in Fig. 8;
this portion including the edge is consequently chilled while the other portion
toward the back of the saw or other cutting tool remains comparatively hot. When
the blade in this condition emerges from between the chilling jaws the chilled
portion will receive the tempering heat by conduction from the not-chilled or

page_text: only partly chilled portions as will be readily understood by those skilled in
the art.
In Figs. 9 to 16 inclusive I have represented another apparatus for hardening
and tempering bands or webs of steel or iron this apparatus being modified from
the one described with reference to Figs. 6 to 8 inclusive only in some minor points
the main features and the general arrangement of the apparatus being the same.
In Fig. 9 the numeral 100 represents a roll of a steel band or web 26 which is
passed to a machine marked by the numeral 101 which may be a rolling-mill for
giving to the band or web the required shape, or the machine 101 may be a tooth-
cutting and setting machine into which a finished web is fed and is there operated
upon to convert the same into a saw.. The latter is supposed to be the case in the
apparatus shown but since the construction of such tooth-cutting and setting machine
is well understood by those skilled in the art and since for the purposes of this
invention it is of no consequence what this construction may be a description of the
same is deemed unnecessary.
It is sufficient to note that the steel or iron band or web 26 enters the machine
at one end in the direction indicated by an arrow and issues at the other end with
the saw-teeth cut and set the arrangement being such that the teeth are formed on
one edge of the blade and it will be understood that before issuing from the machine
the article passes between suitable scouring brushes as has been described with
reference to Figs. 5 and 6.
The saw-web then passes successively between two sets 102 and 103 of contact
rollers 104 which here take the place of the contact brushes shown in the apparatus
Fig. 6, and are mounted in frames 105 which correspond with brush-clamps herein-
before described and to which the electrical connections 42, 42 from the terminals
of the source of electricity are attached. These frames are fitted to dove-tailed
guides upon the bench which in this instance may have only a single ledge 106 as
indicated in Fig. 11. One of each pair of contact rollers can be adjustably fixed in
the frame by a screw and nut 107 the screw passing through a slot in the frame
and the other contact roller of each pair is mounted upon a square stud 108 guided
in a suitable slot and forced forward by a spring 109 so that this roller will auto-
matically accommodate itself to the particular article and will effect a yielding
contact with the same.
::
.
The surfaces of the contact rollers will be shaped to conform to the cross-section
of the article operated upon, this is indicated in Fig. 11 where the article is supposed
to be a saw with the teeth set and where consequently the contact rollers are
bevelled at one edge. This bevel 110 is shown in Fig. 11 on the upper edges of
the contact rollers but when the saw is fed between the contacts with the teeth on
the lower edge as is supposed to be the case in the apparatus shown in Fig. 9 the
bevels on the rollers will be formed on the lower edges of the same as will be readily
understood.
To the rear end of the frame of the set of rollers 103 are secured two heavy
metal plates 111 which project beyond the frame and are inclined toward each other;
the free edges of these plates are lined with enchangeable contact jaws 112. These
jaws are made of such metal as is best suited for the purpose; if the article operated
upon is of considerable thickness the contact jaws are made of copper or other good
conductor but if the article is thin the contact jaws may be made of platinum. As
seen in the drawing these jaws are curved and are gently pressed against each other,
but will yield and separate to admit the web by reason of the elasticity of the long
plates 111.
The purpose of the plates 111 with their contact jaws is to bring the last point of
electrical contact of the web 26 with the heating device as near as practicable to
the chilling device 113. This latter may be of the same character as that repre-
sented in Figs. 7 and 8 or modified as represented in Fig. 14.
The construction of
this slightly modified chilling device is apparent upon inspection. There is a
casting 114 mounted upon the ledges of the bench but insulated therefrom and
longitudinally adjustable thereon. This casting has in its upper face a V-groove

page_text: which is closed at one end by a wall 35" (see Fig. 7) and above the V-groove there
are dove-tailed guides as seen in Fig. 14.
Scated in the dove-tailed guides is the base of the cooling-block so that it may be
moved longitudinally upon the casting 114 and a lug 115 at one end of the cooling-
block will be received within the V-groove if the block is sufficiently moved in one
direction with relation to the casting.
The construction of the cooling-block has been described with reference to
Figs. 7 and 8 and it is now understood that this block is U-shaped in general
outline and has channels 33 in each branch of the U or fork which communicates
with each other, as indicated in dotted lines in Fig. 14 and which also communi-
cate with the pipes or tubes 39 through which a cooling agent is passed into and
through the channels.
The opposing inner faces of the U or fork are each formed with a small
recess 116 into which are sprung the lugs 117 formed on the outer faces of a
U-spring 118 which has the general outline of the inner face of the cooling-block so
as to loosely fit against the same when the lugs 117 are sprung into the recesses 116.
From the inner faces of the U-spring project inwardly the massive cooling
jaws 119 leaving a small space between the same and when the article operated
upon is a saw with its teeth set, the cooling jaws are cut away at the upper ends on
their inner faces as shown, to accommodate the teeth of the saw while that portion
of the blade which extends directly from the teeth is grasped between the jaws by
the action of the spring, which thus exerts a yielding contact pressure upon the
saw blade.
If the teeth of the saw are not set as is sometimes the case, or if the
object operated upon has no projecting portions the cooling jaws will have smooth
inner faces.
Generally speaking the cooling jaws will be shaped to conform to the shape of
the object to be chilled by the same; so if that object be a steel wire each jaw
will have a semi-circular notch; and if the object be a quadrangular rod such as is
used for umbrella-ribs each jaw will have a notch to conform to one-half of the
cross section of such rib.
The chilling device 113 may also be of a different character such as illustrated
in Figs. 12 and 13. In this case it is simply a box 120 which is provided with a
central slot and is filled with material such as ferro-cyanide of potassium, which
will act upon the heated iron article to harden the same. A pipe 121 communi-
cating with a supply of that material and emptying into the box will keep the
latter constantly filled. The box is made rather long so that the article when it
issues from the same will be cold enough to be taken up by the drum 100¹ without
requiring additional cooling.
Feed-rollers 122, 123 placed at each end of the bench are timed to feed the
web or other article continuously through the apparatus with uniform speed.
It will be understood that the adjusting devices used in connection with the
contact brushes and the chilling device in the apparatus shown in Fig. 6 will also
be used in connection with the modified apparatus shown in Fig. 9. In the latter
figure of drawings the devices for re-heating have been omitted for the sake of
simplicity of illustration.
The construction of the brush-clamps 28, 29 is best illustrated in Fig. 15. The
body of the clamp resembles in outline the casting 114 which supports the chilling
device. They are formed with two brackets 124, 124 to which the brush-
holders 125 are screwed and from which the brushes 126 project toward each other
and against the saw or blade or other article. These brush-clamps are of course
insulated from the bench as indicated by black shading.
While any form of generator may be used to feed the heating circuit I prefer to
take the current from the thick wire secondary coil of an inductional transformer
as shown. The current employed should be of a constant but low potential and of
a correspondingly large volume. The generator of such current will necessarily
have a very low internal resistance and for the purposes of this invention this
internal resistance should be very low. The leading-in wires are made very heavy

page_text: so that the internal resistance of the generator together with the resistance of the
leading wires will be only a very. sinall fraction of the total resistance of the
circuit by far the greater portion of which is represented either by the articles
clamped in the frame 7 (Fig. 1) or by that portion of the band or web which
extends between the contact brushes or contact rollers.
With this construction my correspondent secures an automatic regulation of the
current passed through a number of segregated articles operated upon irrespective
of their number and also irrespective of the slight and unavoidable differences of
resistance between the several articles; that is to say with this construction it is
of very little consequence whether each saw-blade or other article 18 has exactly
the same resistance for it will always receive a current inversely proportionate to
that resistance so that all these blades will be heated to the same degree of
incandescence at the same time by current from the same source. My correspondent
for this reason not obliged to charge the frame 7 completely in each instance since,
if the proper relation of resistance is provided a single saw-blade clamped in the
frame 7 will be raised to the same degree of incandescence as a dozen or more.
This automatic regulation of the current and uniformity of heating of several
articles at the same time is the more perfect the greater the resistance of the
article is and compared with the resistance of the remainder of the circuit and
more especially as compared with the internal resistance of the generator as is
well understood by those skilled in the art.
The same automatic regulation is also obtained in the case where successive
sections of a band or web are heated and hardened and tempered.
Suppose for instance the portion of the band which at any moment extends
between the contacts is slightly thinner than the preceding or succeeding portion
or more generally that it is slightly thinner than the standard band for which the
apparatus was adjusted. The immediate effect will be that this thinner portion
representing a scusibly greater fraction of the total resistance of the circuit than
if it were of the standard size will sensibly reduce the flow of current and
consequently this thin portion of the band will receive less current in proportion
to its increased resistance and will therefore be heated to the same degree as any
like section of the standard size.
If on the contrary the section of band extending between the contacts at any
given phase of operation is thicker than the standard size it will receive more
current in proportion to its reduced resistance and will therefore be heated to the
same degree as any like section of the standard size.
This automatic regulation however takes place only when the resistance of the
external circuit which is practically represented by the portion of the band which
extends between the contacts is great as compared with the internal resistance of
the generator. It would therefore scem that the greater the distance between the
contacts the more perfect the self-regulation would be. This is in fact the case so
far as the flow of current is concerned but it is not the case with respect to the
uniform heating; for if the distance between the contacts be great the chances
that a portion of the band extending between the same is thick and another
portion thin are increased and while in that case the flow of current would be
regulated in accordance with the resistance of the whole piece which extends
between the contacts it would not be regulated in accordance with demands of
either the thick or the thin portion of the same. For this reason the distance
between the contacts must be made as small as possible and the internal resistance
of the generator so very small that the external resistance becomes large in
comparison with the same.
Having now particularly described and ascertained the nature of the said
invention, as communicated to me by my foreign correspondent, and in what
manner the same is to be performed declare that what I claim is ;-
1. The method or process of hardening and tempering steel or iron articles by
heating such articles electrically to a predetermined degree of incandescence and

page_text: then immersing the same into a chilling medium while in that state of incandescence;
substantially as described.
2. The method or process of hardening and tempering steel or iron articles
which consists in passing a current of the proper heating effect through such
article until the same has attained a predetermined degree of incandescence;
then interrupting the flow of current and simultaneously therewith immersing
the article in a chilling medium, substantially as described.
3. The method or process of hardening and tempering steel or iron articles
which consists in heating such articles electrically to a predetermined degree of
incandescence then immersing the same in whole or in part into a chilling
medium while in that state of incandescence and then re-heating the chilled
portions to the required temper, substantially as described.
4. The method or process of hardening and tempering steel or iron articles
which consists in passing a current of the proper heating effect through such
article until the same has attained a predetermined degree of incandescence; then
interrupting the flow of current, and simultaneously therewith immersing the
article in whole or in part in a chilling medium, and then reheating the chilled
portions to the required temper substantially as described.
5. The method or process of hardening and tempering steel or iron articles
which consists in heating such articles electrically to a predetermined degree of
incandescence; then immersing the same into a chilling medium while in that state
of incandescence and then re-heating the chilled articles electrically to the required
temper substantially as described.
6. The method or process of hardening and tempering steel or iron articles
which consists in passing a current of the proper heating effect through such
article until the same has attained a predetermined degree of incandescence; then
interrupting the flow of current and simultaneously therewith immersing the
article in a chilling medium and then re-heating the chilled article electrically to
the required temper substantially as described.
7. The method or process of hardening and tempering steel or iron articles
which consists in passing a current or currents of low tension and heating quantity
through such articles until they have acquired a predetermined degree of
incandescence; then stopping the passage of current and simultaneously therewith
immersing the articles into a chilling medium substantially as described.
8. The method or process of hardening and tempering a number of steel or iron
articles simultaneously which consists in passing a current of low potential in
multiple are branches through said articles until they have each attained a
predetermined degree of incandescence; then interrupting the flow of current and
simultaneously therewith immersing the heated articles in whole or in part in a
chilling medium substantially as described.
9. The method or process of hardening and tempering steel or iron articles
which consists in including the said articles into a circuit charged with a current
or with currents of low tension and heating quantity until the articles have acquired
a predetermined degree of incandescence; then breaking the circuit and simul-
taneously therewith immersing the articles into a chilling medium and finally re-
heating the articles electrically to the required temper by the passage through the
same of a lesser amount of current substantially as described.
10. The method or process of hardening and tempering long bands, webs or
rods of steel or iron by passing an electric current or currents through successive
contiguous sections of equal and predetermined length of the article in continuous
and unintermittent succession so as to heat these sections to a predetermined
degree of incandescence and immersing the heated sections in uninterrupted
succession in a chilling medium substantially as described.
11. The method or process of hardening and tempering long bands, webs or
rods of steel or iron which consists in passing the successive sections of such
articles with uniform and continuous speed between the terminals of a circuit
charged with a heating current or currents of electricity, and the heated sections
B

page_text: with the same uniformity and continuity through a chilling medium substantially
as described.
1
12. The method or process of hardening and tempering long bands, webs or
rods of steel or iron which consists, in electrically heating successively contiguous
sections of predetermined length of the article with uninterrupted, continuity and
chilling these sections in like succession and with like continuity substantially as
described.
13. The method or process of hardening and tempering long bands, webs or rods
of steel or iron which consists in electrically heating contiguous sections of the
article in succession; then immersing the heated sections in whole or in part in
succession into a chilling medium and then reheating the chilled portions to the
required temper in like succession substantially as described.
14. The method or process of hardening and tempering long bands, webs or rods
of steel or iron which consists in electrically and successively heating contiguous
sections of predetermined equal length of the article with uninterrupted continuity;
then chilling these sectious in like succession and with like continuity and finally
electrically reheating the chilled sections in the same succession and with the same
continuity substantially as described.
15. The method or process of heating long bands, webs or rods of metal
electrically which consists in passing successive sections of such article between and
in contact with the two terminals of a charged circuit of such low resistance that
the resistance of the section between the terminals is greater than that of the
remainder of the circuit substantially as described.
16. The method or process of uniformly heating long bands webs or rods of
metal throughout their whole length which consists in continuously passing short
successive sections of such article representing the greater part of the total resistance
of a circuit between and in contact with the terminals of such circuit and charging
said circuit with a current or currents of low tension and heating quantity sub-
stantially as described.
17. An apparatus for hardening and tempering steel or iron articles electrically
consisting of a frame for spacing and clamping said articles therein a chilling bath
adapted to receive the frame and an electric circuit including the frame and the
articles clamped therein substantially as described.
18. In an apparatus for liardening and tempering steel and iron articles
electrically the combination of a rectangular frame having two metallic end bars
insulated from each other and provided with means for spacing and clamping steel
or iron articles therein between the end bars a chilling bath adapted to receive the
frame and an electric circuit having its terminals at the end bars of the frame
substantially as described.
19. In an apparatus for hardening and tempering steel and iron articles the
combination of a frame for clamping the articles; with vertical guides permitting
the frame to be raised and lowered a chilling bath arranged below the frame for
receiving the latter when lowered and an electric circuit including the guides and
the frame substantially as described.
20. In an apparatus for hardening and tempering steel or iron articles a rect-
angular frame having metallic end bars insulated from each other and grooved for
the reception of metallic spacing-blocks; in combination with such spacing-blocks
ánd clamping devices therefor and for the articles held thereby a chilling bath
disposed below the frame and an electric circuit including the frame substantially
as described.
21. In an apparatus for hardening and tempering steel and iron articles
électrically the combination of a frame for spacing and clamping the articles; with
metallic guide-posts for raising and lowering the frame thereon and in electrical
contact therewith a chilling bath disposed to receive the frame when lowered an
electric circuit including the guide-posts and frame and insulating sleeves on the
guide-posts for interrupting the circuit when the frame is in its lowest position
substantially as described.

page_text: 22. In an apparatus for hardening and tempering steel and iron articles the
combination of an electric circuit and a frame for including a number of such
articles in multiple arc branches in said circuit and a chilling bath disposed to
receive the frame substantially as described.
23. In an apparatus for hardening and tempering steel and iron articles the
combination of a holder for the articles an electric circuit including the articles in
the holder a chilling bath disposed to receive the holder and a cut-out for auto-
matically interrupting the circuit simultaneously with the immersion of the said
articles in the bath substantially as described.
24. An apparatus for hardening and tempering bands, webs or rods of steel or
iron consisting essentially of successive sets of electrical contacts constituting the
terminals of a charged circuit a cooling or chilling medium and feeding devices for
passing the steel or iron article continuously between the electrical contacts
and through the cooling medium in uninterrupted succession, substantially as
described.
25. In an apparatus for hardening and tempering bands, webs or rods of steel
or iron the combination of two successive sets of electrical contacts constituting
the terminals of a charged circuit and a chilling medium arranged behind the last
set of contacts; with feeding devices for passing the steel or iron article con-
tinuously between the electrical contacts and through the cooling medium in
uninterrupted succession and a cleanser arranged in advance of the first set of
contacts for removing insulating impurities from the steel or iron substantially as
described.
26. In an apparatus for hardening and tempering bands, webs or rods of steel
or iron the combination of two successive sets of elastic electrical contacts con-
stituting the terminals of a charged circuit and a chilling medium arranged behind
the last set of contacts, with feeling devices for passing the steel or iron article
continuously between the electrical contacts and through the cooling medium in
uninterrupted succession and a circuit controller for governing the quantity of
current that passes to the contacts substantially as described.
27. In an apparatus for hardening and tempering bands, webs or rods of steel or
iron the combination of two successive sets of electrical contacts constituting the
terminals of a charged circuit and feeding devices for passing the steel or iron
article uniformly and continuously between the contacts; with a chilling medium
arranged behind the last set of contacts in the path of the steel or iron article for
cooling the same in whole or in part and means for continuously reheating the
chilled portions to the required temper substantially as described.
28. In an apparatus for hardening and tempering bands, webs or rods of steel or
iron the combination of two successive sets of elastic electrical contacts constituting
the terminals of a charged circuit and a set of elastically mounted chilling, jaws
shaped to accommodate between them and to bear partly or wholly against the
article operated upon, with feeding devices for passing the steel or iron article con-
tinuously and uniformly between the contacts and the chilling jaws in uninterrupted
succession substantially as described.
29. In an apparatus for hardening and tempering bands, webs or rods of steel or
iron the combination of two successive sets of main electrical contacts constituting
the terminals of a charged heating circuit and a set of chilling jaws adapted to
receive the steel or iron article between them arranged behind the last set of main
contacts; with two subsidiary sets of electrical contacts forming the terminals of a
branch of the heating circuit arranged behind the chilling jaws and feeding device
for passing the steel or iron article uniformly and continuously between the main
electrical contacts the chilling jaws and the subsidiary contacts in uninterrupted
succession substantially as described.
30. In an apparatus for hardening and tempering bands, webs or rods of steel or
iron the combination of two successive sets of main electrical contacts constituting
the terminals of a charged heating circuit and a set of chilling jaws adapted to
receive the steel or iron article between them, arranged behind the last set of main

page_text: contacts with two subsidiary sets of contacts forming the terminals of a branch
derived from the heating circuit arranged behind the chilling jaws; circuit con-
trollers for the main and derived circuits for regulating the quantity of current in
both and feeding devices for passing the steel or iron article uniformly and con-
tinuously between the main contacts the chilling jaws and the subsidiary contacts in
uninterrupted succession substantially as described
31. In an apparatus for hardening and tempering bands, webs or rods of steel or
iron the combination of two successive sets of electrical contacts constituting the
terminals of a charged circuit and a chilling medium arranged behind the last set
of contacts; with means for independently adjusting the relative distances of the
contacts from each other and from the chilling medium and feeding devices for
passing the steel or iron article uniformly and continuously between the contacts
and through the cooling medium in uninterrupted succession substantially as
described.
32. In an apparatus for hardening and tempering bands webs, or rods of steel or
iron, a chilling device consisting of a casting provided with communicating channels
formed in the body thereof, with pipes or tubes for passing a cooling fluid through
the channels and elastically mounted chilling jaws removably mounted, upon the
casting substantially as described.
33. In an apparatus for hardening and tempering bands, webs or rods of steel or
iron a chilling device consisting of a casting having a U-shaped recess and com-
municating channels formed in the body of the casting with pipes or tubes for
passing a cooling fluid through the channels and a U-spring removably mounted in
the recess and provided with chilling jaws adapted to receive the steel or iron
article between them substantially as described.
34. In an apparatus for hardening and tempering bands, webs or rods of steel or
iron the combination of electrical hardening and tempering devices; with scouring
or cleaning devices in advance thereof and feeding devices for passing the object
operated upon through both in succession substantially as described.
35. In an apparatus for hardening and tempering bands, webs or rods of steel or
iron the combination of two successive sets of electrical contacts constituting the
terminals of a charged circuit and feeding devices for passing the steel or iron
article between the said contacts; with a chilling medium arranged behind the last
set of contacts in the path of the steel or iron article for cooling the same and means
for electrically re-heating the chilled article to the required temper substantially as
described.
36. In an apparatus for hardening and tempering bands, webs or rods of steel or
iron the combination of two successive sets of electrical contacts constituting the
terminals of a charged heating circuit and a set of chilling jaws adapted to receive
the steel or iron article between them arranged behind the last set of main contacts;
with two subsidiary sets of electrical contacts forming the terminals of a branch of
the heating circuit arranged behind the chilling jaws, and means for passing the
steel or iron article between the main electrical contacts the chilling jaws and the
subsidiary contacts in succession substantially as described.
37. In an apparatus for hardening and tempering bands webs or rods of steel or
iron the combination of electrical heating devices; with elastically mounted chilling
jaws and feeding devices for passing the article through both in succession sub-
stantially as described.
38. In an apparatus for heating bands, webs or rods of metal the combination of
elastically mounted exchangeable contacts conforming to the shape of the article
operated upon with feeding devices for passing the article between said contacts
substantially as described.
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W. P. THOMPSON & BOULT,
Agents for the Applicant.