Note: Descriptions are shown in the official language in which they were submitted.
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ORBITAL DENTAL POLISHING DEVICE
Cross-Reference to Related Applications
This application is a continuation-in-part of United States patent
application no. 09/920,046 filed 1 August 2001.
Technical Field
[0001] The invention relates to the field of tools for polishing crowns,
bridges, dental appliances such as dentures and the like, or jewellery, and
more
particularly a device which polishes crowns, bridges, dental appliances such
as
dentures and the like, or jewellery, using an orbital motion.
Background
[0002] Currently dental laboratories prepare crowns, bridges and dental
appliances such as dentures. After a crown is cast out of gold alloy or
porcelain, it
is necessary to polish the upper surface of the crown. The upper or functional
surface of the crown, like a natural tooth, has a complex convoluted shape or
anatomy consisting of convex ridges, concave grooves and a deep central pit.
The
combination of deep anatomy and projecting ridges is important for the proper
functioning of the tooth, and places less stress on the tooth root.
[0003] Currently dental laboratories use a lathe for the polishing of the
crown or dental appliance. Such lathes use a polishing disc brush made of
rigid
brushes which is mounted on a rotating shaft. The edge of the rotating disc
contacts
the surface of the crown. Since the radius of the disc is necessarily too
great for the
disc to enter the pit, it is generally not possible to polish the depth of the
pit without
wearing down the surrounding anatomy. Similarly the disc cannot reach all
parts of
the grooves and ridges without wearing down the anatomy of the crown, which is
undesirable. There is therefore a need for a device for polishing crowns,
bridges or
dental appliances which preserves the anatomy of the crown.
Summary of Invention
[0004] The present invention provides a device for polishing a workpiece
having a convoluted surface comprising: a brush-supporting member; an electric
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motor for imparting an orbital motion to the brush-supporting member; and a
polishing brush comprising a curved working surface mounted on the brush-
support-
ing member. According to one aspect, the brush has a hemispherical face. The
hemispherical face preferably faces vertically downwardly. The device may have
a
horizontal base, and may comprise a vertical motor support. The motor may be
mounted within a motor housing on said vertical motor support. Preferably the
brush-supporting plate extends downwardly from said motor housing and the
device
preferably has a plurality of brushes mounted on said brush-supporting plate.
Brief Description of Drawings
[0005] In drawings which illustrate a preferred embodiment of the invention:
[0006] Fig. 1 is a perspective view of the surface of a crown;
[0007] Fig. 2 is a perspective view of the polishing device according to the
invention;
[0008] Fig. 3 is a side view of the invention;
[0009] Fig. 4 is a detail of the polishing brushes of the invention with the
brush housing removed for ease of illustration;
[0010] Fig. 5 is a view with the housing removed to better illustrate the
orbital motor;
[0011] Fig. 6 is an enlarged perspective view of a brush head; and
[0012] Fig. 7 is a partial sectional view of the brush head shown in Fig. 6.
Description
[0013] Throughout the following description, specific details are set forth in
order to provide a more thorough understanding of the invention. However, the
invention may be practiced without these particulars. In other instances, well
known elements have not been shown or described in detail to avoid
unnecessarily
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obscuring the invention. Accordingly, the specification and drawings are to be
regarded in an illustrative, rather than a restrictive, sense.
[0014] With reference to Figure 1, a crown 10 is shown, which may be of a
precious metal such as gold alloy, or porcelain or acrylic. It has a
convoluted upper
or functional surface 12 having a marginal ridge 14, buccal cusp 16, lingal
cusp 18,
triangle ridges 20, groove 22 and pit 24. These complex features of the
functional
surface are referred to as the anatomy.
[0015] The polishing device 30 of the invention is shown in Fig. 2 through
5. It has a base 32, source of electrical power 34, switch 36, vertical post
38, and
machine housing 40. Attached to machine housing 40 is a brush housing 42.
Extending downwardly from brush housing 42 is at least one, and preferably
three
or more brush heads 44, 46, 48. Brush heads 44, 46, 48 are formed of polishing
brush filaments such as those used to form existing lathe polishing brushes.
Each
brush head has a different profile according to the different desired tasks.
Prefera-
bly the heads of the brushes have curved, generally hemispherical, faces with
different radii to allow polishing of different surfaces. Also, providing
multiple
brush heads allows the use of a different coarseness of polishing compound on
each
brush head, from coarse to fme. The polishing compound is poured into openings
68 of each container 60, which are supported by support 64, and then reaches
the
brush through a tube 62 which connects each container 60 to the brush through
hole
70 (Fig. 6 and 7) of each brush head.
[0016] Brushes 44, 46, 48 are mounted on brush plate SO (Fig. 5) which
extends downwardly from and is secured to plate 52 of orbital motor 54. Brush
plate 50 extends down a sufficient depth so that a technician working at the
device
can see the surface of the workpiece. A suitable motor 54 is from a Random
Orbit
Sander or Finishing Sander such as Makita Finishing Sander model B04552K. This
is a sander in which a point on the sanding surface randomly orbits in a plane
about
a fixed center point Thus a point on the surface of the sander (such as the
brush
head in this case) follows a continuous random motion in a closed path such as
a
circle or an ellipse in a path around a center point in that plane. Such
orbital
motion, like the motion of a planet around the sun, is distinguished from
rotational
motion, such as the spinning of a planet on its own axis. The switch 36 turns
the
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motor on and off without speed variability. A motor having a variable speed
may
also be used, although a variable speed is normally not required.
[0017] In operation, the technician having a gold crown to polish turns on
the orbital motor 54 which imparts to brush heads 44, 46, 48 a rapid orbital
motion,
much as in an orbital sander. The technician then selects the brush with the
appropriate radius and/or polishing compound and contacts the surface of the
crown, thereby polishing it. Unlike the prior polishing devices, the anatomy
of the
crown is not thereby reduced.
[0018] While the invention has been described for purposes of polishing
crowns, bridges and dental appliances such as dentures, the invention is
useful for
polishing any non-planar surfaces and particularly non-planar surfaces with
complex
or convoluted curvatures, including jewellery, small die-made parts and
computer
chips.
[0019] As will be apparent to those skilled in the art in the light of the
foregoing disclosure, many alterations and modifications are possible in the
practice
of this invention without departing from the spirit or scope thereof.
Accordingly,
the scope of the invention is to be construed in accordance with the substance
defined by the following claims.
