Toolholder or Hand-piece for Dental Drilling Machines and analogous Implements.
Year: 1894

page_text: Date of Application, 28th May, 1894-Accepted, 30th June, 1894
COMPLETE SPECIFICATION.
Toolholder or Hand-piece for Dental Drilling Machines and
analogous Implements.
1, THEOPHILE DILL-RICHARD, Dentist, of Liestal, Switzerland, 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 angular hand-pieces or tool-holders generally used for holding and guiding
the tools of dental engines or drilling machines, such as drills, burs, burnishers, and
rotary brushes, are attended with the inconvenience, that, while the tool is in
operation, the enamel and bone dust penetrating between the contact surfaces of the
revolving chuck or clamping collar carrying the tool, and the stationary handpiece
frame, is apt, owing to the great speed with which the tool revolves, rapidly to
wear out those parts, however carefully they may be lubricated, with the result,
that the said clamping collar or chuck soon becoines loose in its frame or holder,
and that consequently the tool gets out of centre and will no longer work as
accurately and safely as it is required to do, and the handpiece itself becomes unfit
for further use. Another disadvantage of the old arrangement is this, that the one,
cylindrical, end of the tool is usually fitted in the said chuck by inserting it between
the slightly resilient cheeks of the same and securing it by a kind of bayonet
joint, so that the tool is not held with sufficient security and accuracy, even in the
chuck.
To remedy these drawbacks, an improved angular hand piece has been devised,
the construction of which forms the subject of this invention. The chuck or socket
piece which receives the tool in the improved arrangement, rests with its two
conical ends, one of which is adjustable, within two correspondingly bevelled
bearings of the angular hand piece, which permits the gradual wear to be
compensated in proportion as it takes place. In addition to this, the end of the
tool which is to be fitted in the chuck or socket is bevelled, as is also the bore
provided for its reception in the socket piece, so that the external pressure to which
the tool is subjected, tends to press it more firmly into the said socket. To render
the position of the tool in the socket still more secure, it may be threaded at the
end which the socket-piece is to receive, the latter being correspondingly tapped,
and the connection being consequently produced by screwing, which will effectually
preclude the tool from becoming loose of its own accord.
The invention will be best understood by reference to the accompanying
drawings, of which
Fig. 1 represents a rectangular hand piece constructed in accordance with this
invention and having a bur fitted to it, in longitudinal section.
Fig. 2 is a cross section along line X-X of Figure 1.
Fig. 3 also shows the angular hand piece, though only in dotted lines, as attached
to one of Shaw's dental engines; and
Figs. 4 and 5 show respectively an acute-angled and an obtuse-angled hand piece
embodying the same principle, as that which the Figures 1 and 2 illustrate.
It will be seen from these drawings, that the casing A of the hand piece, may be
arranged on the fastening tube B, either at a right-angle, acute-angle, or obtuse-
angle. This tube B which serves for fastening the angle piece to the straight hand
piece H of the dental engine, is slid on to the front part of the latter and retained
therein by means of a spring controlled hook, or by a bayonet joint. In the centre
of the tube B, there is arranged a spindle C, one end of which is provided with a
flattened portion c, adapted, when the angle piece is fitted in position, to come into

page_text: contact with another similar flat face formed on the spindle C' (Figure 1) which
terminates in the straight piece H and is operated by the driving mechanism of the
drill; by which contact of flat surfaces one spindle is carried round by the other,
as it revolves. Upon the opposite end of the said spindle C there is mounted
a bevel wheel D which extends into the casing A and is in gear with the other bevel
wheel E, secured to the socket piece F which is to receive the tool. This socket
piece F has a conical bore f of which the lower and narrower part, however, is of
cylindrical shape, and tapped with an inner screw thread, so that the conical
threaded portion g of the end g₁ of the tool G, in being inserted into the socket
piece F, may be firmly secured therein by screwing, thereby obviating any tendency
of the tool to become loose accidentally. To facilitate the removal of the tool G
from its socket, when required, the lower end of such tool is provided with a
notch go, in which a screw-driver can engage. If desired the threaded portion g
of the tool G may be dispensed with, as sufficient firmness may be ensured by
simply fitting the conical end d' of such tool into the correspondingly shaped bore
of the socket piece F, the firmness of the connection being enhanced, as before
stated, by the external strains which the said tool sustains.
The bevelled oblique end f¹ of the socket picce F rests within a correspondingly
bevelled recess of the aperture a¹ formed in the bottom a of the casing; while the
upper bevelled portion f2 of the said socket piece F bears on a conically hollowed
out disc I. This disc is loosely inserted into the casing A open at the top, and a
notch which is provided in its periphery, wherein engages a projection aº raised on
the casing A, prevents this disc from turning. The said disc is pressed against the
cone by the nut J screwed on to the open end of the casing A, which is threaded
externally for the purpose, the bottom part of such nut grasping or enclosing the
said disc I; owing to which arrangement, as the conical surfaces wear off, it is only
necessary to tighten the said nut, J to compensate for the wear, so that in no case
need the socket piece F become loose in the casing A. The cylindrical edge or
flange of the nut J is provided with slots j, so that this edge or flange is resilient
and tightly grasps the casing A, thereby obviating any spontaneous rotation.
The casing A may be filled with a suitable lubricant, when all the revolving parts
will be automatically lubricated while in operation, and no escape of the oil from
the casing A need be feared.
Having now particularly described and ascertained the nature of the said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is ;-
1. An annular hand piece for dental engines and analogous implements in which
the two conical ends of the sleeve or socket piece F, adapted to receive the tool,
such as a drill, burr, or burnisher, and provided with a driving wheel E, are held
in two correspondingly bevelled or hollowed out bearings a and I, one of which is
adjustable by means of a resilient nut J screwed on to the casing A of the angle
piece so that as the friction surfaces wear out through contact with each other,
the socket piece or chuck F may be prevented from getting loose by re-adjusting
the bearing I, and at the same time the said casing A is closed tightly at both ends,
substantially as described.
2. In the annular hand piece specified by the first claim, a chuck or socket piece
having a conical bore and an inner screw thread fitted to receive the correspondingly
threaded end g of the bit or tool for the purpose of securing the tool in its socket
piece F.
Dated this 26th day of May 1801