An Improved Process for Facilitating the Cutting or Abrading of Metals.
Year: 1889

page_text: COMPLETE SPECIFICATION.
An Improved Process for Facilitating the Cutting or Abrading of
Metals.
I, BENJAMIN CHEW, TILGHMAN, of 1114 Girard Street in the City and County of
Philadelphia, State of Pennsylvania, United States of America, manufacturer, do
hereby declare the nature of my 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 the cutting or abrading of metals and the object thereof is
to facilitate such operations by successively fusing or softening by an electric current,
the small portions of the metal operated upon by the cutting or abrading tool
employed. Heretofore metal rods have been severed by passing heavy currents.of
electricity through the part to be operated upon so to heat and soften the bar through
its whole section and then dividing the bar by tensional strain or by the use of
ordinary cutting tools; but my object is to provide a method by which metal objects
can not only be severed but also planed, turned, or shaped in any ordinary way and I
avoid as far as possible heating the metal under treatment except at the point where.
the cutting or abrading action is taking place. This I accomplish by concentrating
the electric current and the abrasion upon a path or continuous series of small spots
or points adjoining each other and successively brought under the influence of the
current and the abrading tool so that the metal is always heated to the desired degree
at the point where it is being operated upon and not elsewhere.
In carrying my invention into practice, I prefer to use electric currents of large
quantity and low intensity (I do not however confine myself thereto); said currents
being either continuous, intermittent, alternating or undulatory; and I arrange the
metal object to be operated upon so as to form one electrode while the other (preferably
the cutting or abrading tool itself) is made to come in contact with the metal object at
or substantially at the point where the mechanical cutting action is taking or about to
take place, the passage of the current from the one electrode to the other at the point
of contact which is also the point of maximum electrical resistance, softening or fusing
the metal at that point and greatly facilitating the operation of cutting. The
conductors and electrodes should of course be sufficiently large to offer but little
electrical resistance and they must be properly insulated so as to confine the current
to the point of contact. As already noted I prefer to make the cutting tool itself one
of the electrodes for the obvious reason that in no other as convenient way can the
point at which the metal is most bighly heated by the current be made to so perfectly
coincide with the point where the cutting tool is acting upon the metal, and what I
believe to be the best method of carrying my process into effect is to construct the
cutting or abrading tool in the form of a rotating disc made of metal or other
conducting material and electrically connected with the source of the current; the
metal object to be operated upon is then properly secured to a table, lathe or other
support and electrically connected with the source of supply and both electrodes
being properly insulated the edge of the rotating disc is made to press with force
against the surface of the metal object so as to complete the electric circuit and cause
the surface of the object to become heated to softness or fusion at the point or area of
contact while at the same time the friction of the rotating disc scrapes away some of
the softened metal and in case its motion is very rapid, aids by its friction, in softening
the metal. The metal object operated upon is gradually fed up to the rotating disc
so that a continuous cut is made analogous to that made by a milling tool, emery
wheel, the tool of a lathe or the tool of a planing machine; or of course instead of
feeding the object beneath the disc the rotating disc may be fed and guided over
the surface of the metal obiect.

page_text: The surface speed of the rotating disc is much greater than the feed motion of the
object operated upon so that the touching and conducting spot of the disc is constantly
being changed and it is thus subjected to the passage of the current during a much
shorter time than is the conducting spot of the surface operated upon; consequently
the disc does not become as hot as that surface and the temperature of the disc may
be lowered by artificial cooling if desired as can also the temperature of the object
being operated upon. The operation may be performed under water if desired.
It is desirable that the heating of the spot of metal surface of the proper degree of
softness should be done as quickly as possible so as to minimize the loss of heat by
conduction and the current of electricity used for a given area of contact should be,
both in quantity and intensity, amply sufficient for this purpose. Suitable means,
such as are well-known by electricians, should be provided for measuring and regulating
the current.
Reference being now had to the drawings which illustrate my invention and in
which, Figure 1 shows my preferred plan of employing a rotating disc to convey the
current as well as act as the abrading tool; while Figure 2 shows how my invention
can be applied where for any reason it is undesirable to use the abrading tool to
convey the current.
:
In Figure 1, A is a metal disc capable of being rapidly rotated and connected
with the source of electrical supply by a conductor C. The disc is electrically
insulated and preferably mounted on a frame so that it can be moved in any
direction like the tool of a lathe or planing machine. B is the metal object to be
operated upon. It is connected by a conductor D so as to form the other electrode
for the current. It is insulated and mounted on any convenient table or support
to maintain it in contact with the rotating disc and permit of its proper movements
while being operated upon.
It will of course be evident that when the edge of the rotating disc A is
brought in contact with the object B so as to complete the circuit, the current
passing through the point of contact will heat to softness or fusion a thin layer
of metal which is immediately scraped or cut away by the friction of the rotating
disc and as the object B is fed up to the rotating disc A, a continuous cut
will be made as by the tool of a planing machine, so that of course by giving
the proper relative movements to the abrading tool and the object operated upon,
the same results will be obtained as in an ordinary planer.
In Figure 2, B¹ is the metal object to be operated upon, here shown as a wheel
to which the electric conductor D is connected and which can be rotated as indi-
cated by the arrow. The other conductor C instead of being connected to the
abrading tool, connects with a separate pole E which is brought in contact with
the metal object B¹ to melt or soften a spot on its surface. F is the abrading tool.
The pole E is arranged so as to deliver the current as near as possible to the
spot where the abrading tool is operating so that the motion of the object under
treatment will carry the heated spot under the abrading tool as quickly and with
as little loss of heat as possible. The pole E is made preferably of carbon and
arranged so as to maintain an arc discharge into the surface of B¹. The abrading
tool F may be made of steel and toothed like a circular saw; or it may be made of a
non-conducting material like a grindstone or emery wheel.
My invention can be applied to lathes, to milling, planing, and grinding machinery
and generally to all operations where metal is to be cut or removed and where an
abrading tool can be made to act in combination with an electric current so as to heat
successive portions of the metallic surface to softness or fusion.
My process can be applied to all the metals and alloys used in the arts. Hardened
steel and chilled cast iron will be cut or abraded by its use.
I have referred to the cutting tool which I prefer to employ as a rotating disc
but it will of course be understood that any suitable tool having a continuous or
alternating motion like a band-saw or reciprocating saw, might be used, and that
the edge of the tools may be smooth or toothed.

page_text: 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 The process of cutting or abrading metals which consists in heating by an
electric current successive small portions of the metal surface and simultaneously
removing the heated metal by an abrading tool.
Second The process of cutting or abrading metals which consists in passing a
current of electricity through the successive points of contact of the metal being
treated and the abrading tool.
Third: The process of cutting or abrading metals which consists in passing a
current of electricity through the successive points of contact of the metal being
treated and a rotating abrading tool.
Dated this 10th dov of December 1884
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, Agents for the Applicant.