Improvements in Electric Hammers and the like.
Year: 1896

page_text: Date of Application, 31st Mar., 1896-4ccepted, 7th Nov., 1896
[Communicated from abroad by ARTHUR S. BARNES and PERRY S. SKINNER, of
Oneonta, in the State of New York, United States of America, Dentists.]
Improvements in Electric Hammers and the like.
I, HENRY HARRIS LAKE, of the Firm of Haseltine, Lake & Co., Patent Agents,
45 Southampton Buildings, in the County of Middlesex, 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 :-
The invention relates particularly to that class of electrical apparatus, known as
"electric hammers," or "electric mallets," in which a reciprocating armature is
employed to deliver blows upon a tool, held against an object.
The article which has been selected for the purpose of illustration, is a device
combining an electro magnet, having an automatically reciprocating armature with
a tool-holder provided at its lower end with a tool, and designed for use in the
practice of dentistry.
Figure 1 is a front view of this device.
Figure 2 is a vertical cross sectional view of Figure 1, as cut by a plane passing
through its axis, and perpendicular to the plane of the paper, some of the parts not
being in section.
Figure 3 is an horizontal section on the linea of Figure 2.
Similar letters refer to corresponding parts throughout the several views.
A.
The electro-magnet consists of a coil of wire A placed on a soft iron core B
formed in the shape of a hollow cylinder having a flange b on its lower end.
disc of insulating material similar to the flange b is fastened on its upper end and
holds the coil in place. A cylindrical enclosing case H surrounds the coil and is
suitably connected with the flange b. Into the lower end of the core B is screwed
a hollow arm E in which works a tool holder in the form of a rod c terminating at
its lower end in a head C in which any desired kind of tool, as c¹, may be held.
The rod e passes up through the hollow center of the core B, and carries at its
extreme upper end a contact point c², preferably of platinum.
The armature D of the electro-magnet extends over the top of the same and
partly projects into the hollow center of the core B, and is supported and carried
by a sleeve d, loosely surrounding the rode above the hollow arm E and within the
center of the core. This armature is normally held away from the pole of the
magnet by means of a retracting spring d', surrounding the sleeve d, and interposed
between the armature and the top of the hollow arm E. The armature is prevented
from rising above the top of the rod c, by means of a nut c³ on the latter, and is
freed from jarring in its movements by a spring, surrounding the nut c³ and held
against the upper surface of the armature.
At the point where the rod c enters the hollow arm E, it carries a collar c, the
lower edge of which by striking the shoulder e in the hollow arm, limits the
downward movement of the rod. This collar is provided with a feather c which
works in a groove in the hollow arm and prevents the rod c from rotating about its
axis, but leaves it free to reciprocate parallel to the same. Below the collar c and
surrounding the rod c is a loose sleeve c, which is prevented from rising in the
arm E by means of the shoulder e³. A helical spring e', surrounding the rod and
interposed between the sleeve and the head C forces the rod downward. The
shoulder e above the bead C limits the upward movement of the rod. The space

page_text: therefore through which it is free to reciprocate is equal to the distance, when the
rod is in its lowest position, between the shoulder e and the head C. The arm E
is suitably insulated at e from the hand of the operator.
An arm h, overhanging the upper end of the rod c, is attached to the enclosing
case H, and suitably insulated therefrom and adjustable thereon so as to be moved
away from or toward the end of the rod. A spring is carried by the overhanging
arm and is provided with a contact plate h², preferably of platinum, placed
directly above the platinum point c², so that by forcing the rod c upward against
the spring, an electrical connection will be established.
The overhanging arm in the drawings is held in a strip of suitable insulating
material rendered adjustable on the enclosing case H, by an adjusting screw h³,
working in a projection * on the case, and bearing against the end of the insulating
strip. A set screw h' passing through the slot 8 in the strip secures the same
when adjusted.
The enclosing case H is constructed of soft iron, and is closely fitted around the
flange b, so as to form with the hollow core B a single magnet, of which the upper
edge of the enclosing case constitutes one pole, and the upper end of the hollow
core constitutes the opposite pole. It will thus be seen that both poles act directly
upon the armature D.
The positive and negative wires and t leading to a battery, or other source of
electrical supply, are properly insulated from each other, and are connected to a
universal joint m, n carried by the enclosing case H and insulated therefrom by a
strip of any suitable insulator, electrical connections being made by the frictional
contact of the bearings.
The special form of universal joint shown in the drawings, is obtained by means
of four pivot pins 1, 2, 3 and 4, arranged diametrically opposite and so imbedded
in a mass k of insulating material as to be electrically connected in the
pairs 1, 2, 3 and 4, each pair, however, being insulated from the other. The
pins 1 and 3 work in the bearings m and s which form the terminations of
the wires and t respectively, while the pins 2 and 4 work in the bearings n and r
attached to the insulating strip . In order to obtain a better electrical connection
than would be secured by the frictional contact between the pivot pins and their
respective bearings, pressure pieces n¹ and are shown attached to the
bearings n and r, and pressing against the ends of their respective pivot pins.
The wire is electrically connected with one end of the coil A, through the
bearings m and n, of the universal joint m, n, and through the wire o, and the other
end of the coil is connected by the wire p with the overhanging arm h.
The frictional contact between the rod c and the hollow arm E, and the contact
between the latter and the enclosing case electrically connects these parts, and by
the short wire g attached to the enclosing case, and through the bearings r and s of
the universal joint, they are connected with the wire't.
The operation of the device is as follows:
The tool c is pressed against an object which forces the rod c with its contact
point c² against the contact plate 2 and completes the circuit. The armature is
drawn toward the magnet and the sleeve d strikes the collar c delivering a blow to
the tool-holder. By the movement thus imparted to the rod c relative to the
magnet and its enclosing case, the point and the plate 12 separate and break the
circuit, the armature returning to its upper position by the action of the spring d¹.
As the tool is held pressed against the object, contact is immediately restored, and
the operation is repeated, a succession of blows being imparted to the tool-holder.
Having now particularly described and ascertained the nature of the inven-
tion and in what manner the same is to be performed, as communicated to me by
my foreign correspondents, I declare that what I claim is:-
1. The combination of an electro-magnet, an armature, a tool-holder whose
reciprocations are controlled by the movements of the armature, supply wires
leading to and from the electro-magnet, and a device for maintaining the continuity

page_text: of the electric circuit between the terminals of the sapply wires an1 the coil of the
electro magnet comprising a swivel connection, substantially as specified.
2. The combination of an electro-magnet, a vibratory armature, a tool holder
whose reciprocations are controlled by the vibration of the armature, means for
making and breaking the circuit through the cil of the electro-magnet, supply
wires leading to and from the electro-magnet, and a device for maintaining the
continuity of the electric circuit between the terminals of the supply wires and the
coil of the electro-magnet comprising a swivel connection having two axes of
motion at right angles to each other, substantially as specified.
3. The combination of an electro-magnet having an interior bore or cavity, a
tool holder extending through said cavity and mounted to have a lengthwise
movement therein, a sleeve encircling said tool holder and movable indepen lently
of the latter, a stop against which sail sleeve impinges to cause a movement of the
tool-holder, an armature whose movements control the movements of the sleeve,
and means for making and breaking the circuit through the coil of the electro-
magnet to cause the vibration of the armature, substantially as specified.
4. The combination of an electro-maguet having an interior bore or cavity, a
tool holder extending through said cavity and mounted to have a lengthwise
movement therein, a sleeve encircling said tool-holder and movable independently
of the latter, a stop against which said sleeve impinges to cause a movement of the
tool holder, an armature whose movements control the movements of the sleeve,
and a make and break device interposed in the electric circuit through the coil of
the electro magnet, comprising an arm supporting a contact piece and a contact
piece moving simultaneously with the tool holder, substantially as specified.
5. The combination of an electro-magnet comprising an inner and an outer
cylindrical shell, a tool holder extending lengthwise through the bore of the inner
shell and mounted to have a lengthwise movement therein, a piece comprising an
armature movable toward and away from the electro-magnet, a stop against which
this piece impinges to move the tool holder, and means for causing the vibration of
said piece to impart a reciprocating movement to the tool-holder, substantially as
specified.
6. The combination of an electro-magnet, a tool-holder, a piece comprising an
armature, movable independently of the tool-holder and adapted to impart to the
latter a number of rapidly succeeding blows, and a circuit breaker interposel in the
circuit comprising the coil of the electro-magnet, and consisting of a contact piece
movable with the tool holder, and an adjustable arm supporting a second contact
piece adapted to coact with the first mentioned contact piece, the circuit through
the circuit breaker being closed by pressure upon the tool holder and opened by the
forward movement of the same, substantially as specified.
7. In combination with an electrically operated tool, a swivel connection for
attaching electrical supply wires, comprising a mass of insulating material, pivot
pins which are in electrical communication with said supply wires, are imbedded in
said insulating material and have ends projecting therefrom, and pieces in which
said pivot pins are journaled and through which the continuity of the electric
circuit is maintained, substantially as specified.
Dated this 31st day of March 1896.
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicant.