Improvements in the Method of and Means, employed for Hardening the Points of Serrated or Saw-tooth. Wire.
Year: 1894

page_text: Date of Application; 28th! May, 1894
Complete Specification Left, 8th Feb., 1895-Accepted, 6th Apr., 1895.
PROVISIONAL SPECIFICATION.
Improvements in the Method of and Means, employed for Hardening
the Points of Serrated or Saw-tooth. Wire..
I, JOHN, PLATT of George Hotel Cleckheaton in the County of York
Commercial Traveller, do hereby, declare the; nature of this invention to be as
follows:-
This invention relates to improvements in the method of and means employed:
for hardening the points of the: teeth, of serrated or saw: tooth wire,.of.the class
known as "Garnett" wire, and consists in the employment of electricity.whereby.
the points only of the teeth are hardened..
A convenient and suitable method of carrying the invention into effect, is as,
follows:-
The rib of the serrated wire is carried in a groove formed in an insulated place.
connected to say the pole of a dynamo or other source of electric supply.
Above the grooved plate is a second insulated. plate of metal, preferably copper
carried on an axis in such a manner that the; lower, edge of the plate rests upon or
touches the projecting points of the teeth of the serrated wire, the said plate being
held in contact with the teeth by means of a light, spring. The second plate is
connected to say the + pole of the electric supply.
When in operation the serrated wire is drawn along the groove, and the current
of electricity passes through the each successive tooth and the rib of the wire and
heats the point of each tooth, the wire being then passed into a cooling medium the
points of the teeth are hardened..
The rib of the serrated' wire being much thicker than the tooth the rib is not
heated to the extent of the points of the teeth so that the rib itself, is not effected
and remains unhardened..
The points of the teeth of the serrated wire may be hardened whilst passing.
through the cutting machine and after being cut..
A reciprocating or to and fro, motion is preferably given to the second plate to
prevent it being burnt or worn unevenly..
1
1004
BRIERLEY, & HOWARD,.
Penny Bank, Chambers, Halifax, Agents for the Applicant...
COMPLETE SPECIFICATION.
Improvements in, the Method of and Means employed for Hardening
the Points of Serrated or Saw-tooth Wire.
I, JOHN PLATT of George Hotel Cleckheaton in the County of York England,
Engineer, lately engaged as Commercial Traveller, do hereby declare the nature of
this invention and in what manner the same is to be performed; to be particularly
described and ascertained in and by the following statement :-
This invention relates to an improved process of, and apparatus for hardening:
D
017

page_text: the points or teeth of serrated or saw tooth wire of the class known as "Garnett "
wire the hardening being effected by means of an electric current, which is applied
in such a manner that the points only of the teeth are hardened, and not the rib of
same.
Such being the nature and object of my said invention the following is a
complete description of same reference being had to the accompanying drawing
in which
Fig. 1. is a side elevation of an apparatus suitable for the purpose part being in
Fig. 3 is a section of Fig. 1 on line X. X.
Fig. 4. is a plan of the under surface of the wire, and
Fig. 5 is an end section of same.
The operation consists in heating the points of the wire to such a degree as will
cause them to harden when quenched in a suitable cooling medium the rib and
thicker portion or root of the tooth remaining practically cold not being affected or
hardened.
The operation is effected by bringing one terminal or pole of a source of
electricity into contact with the rib or thick part of the wire, and the other
terminal or pole in contact with a tooth or teeth, so that the circuit is closed or
completed.
A current of electricity of sufficient intensity to raise the temperature of the
point of the tooth to a red heat will leave the base of the tooth and rib com-
paratively cool.
The wire being steel will harden at the point when suddenly cooled thereby.
ensuring greater durability, and the rib will remain soft, thus allowing it to be
wrapped or coiled round the cylinder as required.
The operation of the apparatus is as follows:-
The wire C is unrolled from a reel or bobbin and passes through a trough H
containing a suitable cooling medium preferably oil the wire being threaded
through small slots or holes in the ends of the trough.
The trough which is metallic is connected with terminal A and constitutes one
pole, and the serrated wire comes in contact with it on the block E which is
grooved to the guage of the rib of the wire as shewn in Fig. 3.
An arm F adjustably held by means of a screw F to a stud O which forms an
axis secured on the upright L constitutes the second pole through terminal B
connected with it.
The rib of the wire as it travels along is constantly in contact with the block E
which is one pole and the points of the wire successively touch the end of the
arm F which is slightly bevelled at its extremity (Fig. 3) so as to touch the points
of the teeth only.
This heating operation is carried on beneath the level of the cooling medium,
that is to say:-the points become red hot despite the fact that the wire is
surrounded by oil or water or other cooling medium of low conducting power.
The process has several advantages: As the wire travels along and leaves the
electric circuit which exists between E and F. the cooling medium chills it
instantly, thus preventing the radiation of the heat which is very rapid from the
point to the rib.
The liquid cooling medium prevents the disruptive sparks which are caused by
the extra current (as each point breaks contact with arm F) from burning and
dulling the points, and also from rapidly deteriorating the extremity of the arm by
contact with the points which have a tendency to "weld" to the arm F when the
operation is carried on in the open air, but which points leave the arm quite freely
when under the cooling medium. The level of the medium J is kept up by the
feed pipe K.
I am aware that machines are actually in use by means of which the points of
"Garnett" serrated wire are hardened after being heated by means of a flame, but

page_text: this process is both costly and unsatisfactory owing to the difficulty of heating the
points to a hardening heat without at the same time heating the rib and rendering
it brittle when cooled.
The section of the wire however is such that by the electrical process the point.
must be hot while the rib remains cool.
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 :-
(1.) The process of hardening the points of serrated or saw tooth wire which.
consists in subjecting the points of the teeth of the same to the heating action of an
electric current without heating the rib of the wire, and consequently cooling the
wire for the purpose set forth.
(2.) The process of hardening the points of serrated or saw tooth wire which
consists in subjecting the teeth of same to the heating action of an electric current,
while the wire is surrounded by a liquid cooling medium so that the points only of
the wire are hardened substantially as and for the purpose set forth.
(3.) In an apparatus for hardening the points of serrated or saw tooth wire the
combination of a trough, a liquid cooling medium therein, a block in the trough
below the surface of the liquid, said block forming one pole of an electric circuit,
an arm forming the other pole, the end of the said arm being arranged to touch
the points of the teeth only, and means for carrying the arm substantially as
described.
100
VID
JOHN PLATT,
By his Agents, Brierley & Howard,
Penny Bank Chambers, Halifax.