Improvements in Magnetizing and Demagnetizing Apparatus.
Year: 1895

page_text: Date of Application, 5th Mar., 1895-Accepted. 13th July, 1895
COMPLETE SPECIFICATION.
Improvements in Magnetizing and Demagnetizing Apparatus.
I, CHARLES HOULGRAVE, a citizen of the United States, residing at St. Claire
Hotel, in the City of Richmond, County of Henrico and State of Virginia,
Mechanic, 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 electro-magnetic devices for affecting the magnetic status
of articles in general; and more particularly to those devices used in the
magnetization and demagnetization of watches, compass needles and similar
articles; and it has for its object to provide a device of this cature which shall be
cheap and simple of construction, accurate of operation and which, inoreover, may
be operated equally well with either a continuous, pulsating br'alternating ourrent.
In the accompanying drawings forming a part of this Specification:-
Figure 1, is a plan view of the apparatus, the cover thereof being removed.
Figure 2, is a longitudinal section of the apparatus having the cover
in place.
Figure 3, is a section on line z-z of Figure 1.
Figure 4, is a diagrammatic representation of the circuits through the device.
Figure 5, is a view of the slide for holding the article to be operated upon.
Referring now to the drawings:-
a is a casing composed of wood or other cheap non-magnetic substance, and of
such dimensions as to receive the mechanism of my apparatus, which mechanism
comprises a frame b of similar material, consisting of a hollow square body having
upwardly and downwardly projecting ribs c, d ; e, f and g, respectively, forming
recesses h, i, j, and k, for purposes as will be presently explained.
The floors of the diametrically opposite recesses and I prefer entirely to
remove and in place thereof to substitute a single layer i and m of paper, oil cloth,
or other similar magnetically permeable material to receive the windings n of
insulated wire to form an inducing solenoid.
Exterior of this solenoid, which in this drawing is shown as being rectangular in
cross section, and within the recesses and, which for this purpose are formed
rather deeper than the recessos and k, are'arranged'electro-magnetic poles 29 and 30,
formed of laminals of soft iron, set on edge and lying at an augle to the bore of
the solenoid, the said laminals of said cores being arranged longitudinally of the
windings. Thus it will be seen that the magnetic axis of an article placed within
the solenoid will be in the normal 'direction, but' that the lines of the field will be
scattered, due to the action of the exterior pole pieces, and in consequence there
will be a more even notion throughout the watch or other article within the
solenoid.
Within the openings o of the frame b, is arranged to slide a plate p (Figure 5),
in suitable, grooves in the interior walls of said opening. This plate p is provided
with a any desired number of stationary clips such as a' and ' and with an adjustable
clipe for Holding the article to be operated upon in place.
"In Figure 2, the position of a watch undergoing treatment is indicated in dotted
lines.
In the rece
h of the frame b, is arranged a pole changing device or alternator,
consisting of a cylinder of insulating material suitably journaled in bearings t

page_text: extending longitudinally of the cylinder s. The said plates are arranged in such
positions as that their fingers will assume diametrically opposite positions on the
cylinder a, said fingers being narrowed so as to permit the insertion between them
of plates and y, in electrical relation to each other, such relation being secured
through the medium of suitable connections 5, as shown in Figure 2 of the
drawings.
Suitable brushes of brass or other material, are arranged to bear against the
plates of the alternator, the brushes 6 and 8 bearing against the continuous portions
of plates and w, respectively; the brushes 7 and 9 are arranged centrally of the
alternator and bear against the fingers of the plates and to and against
plates and y, in accordance with the position of the alternator.
The shaft 10 of the alternator is provided at one end with a pinion 11 arranged
to be engaged by a gear wheel 12 movable in its bearings to accomplish such
engagement. Secured also to the interior of the casing is a spring switch 13
passing across the center of gear 12, whereby when the said gear is brought into
engagement with the pinion 11, said switch may be caused to make contact with
point 14, which said point is in connection with brush 8.
Thus my invention may be operated under four distinct conditions which I shall
now describe, setting forth the connections in each instance, reference being had to
Figure 4 of the drawings.
The
I find that my device is especially adapted for the demagnetization of needles
employed in the manufacture of compasses. To secure this result, the needle is
secured to the plate 15 in the manner described, or by other suitable means, which
plate is then pushed into the enclosure of the solenoid until the needle thereon is
brought into the portion of the field of greatest intensity of the magnet n.
gear wheel 12 is then revolved slowly, by means of the crank 16, and is pressed
inwardly in order to mesh with the pinion 11 and to make connection of the
switch 13 with its point 14, the slide and watch thereon being then slowly
withdrawn.
It will thus be seen that by the use of the pole changer or alternator, an
alternating current is passed through the magnet n said current having long time
phases by virtue of the slow revolution of the gear wheel and consequently
the alternator, which, according to the well known principles, will effectually
magnetize any paramagnetic substance under its influence.
With the employment of the continuous current, the alternator being in the
position shown, the circuits are as follows:
Generator G, binding post 1, fuse wire 17, binding post 2, brush 7, finger 19,
base of w, brush 6, point 14, switch 13, point 28, point 20, winding of magnet n,
point 21, brush 8, plate v, finger 18, brush 9, post 3, to generator G.
When one quarter of a revolution is made, the circuit is generator G, post 1,
fuse 17, post 2, brush 7, plate y, plate, brush 9, post 3, to generator G.
A second quarter revolution being made, the electro-magnet is again brought into
circuit as follows:-
:-
Generator G, post 1, fuse 17, post 2, brush 7, plate y, finger 18, plate u, point 21,
winding of magnet n, point 20, point 28, spring switch 13, point 14, brush 6, base of
plate 10. finger 19, brush 9, post 3 and generator G.
A third similar partial revolution again short circuits and a final quarter
revolution brings the alternator into its original position.
The object of thus successively cutting into circuit the magnet and short
circuiting the dynamo, is to give opportunity for the escape of all residual
magnetism from the electro-magnet and at the same time to maintain an approximate
load on the generator, thus insuring its even running and a consequent similitude of
phases, through the apparatus.
To demagnetize a watch the same rules are observed as in the preceding
instance, with the exception of the speed of revolution of the alternator which
must be greatly increased, resulting in rapid alternations of the polarity of the
electro-magnet.