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Patent Abstract
A method for manufacturing finger rings, bracelets, earrings, body
jewelry and the like which have at least one curved surface, and
which are inlaid with a precious metal or which have which have
been subjected to deposition thereon of a metal compound via chemical
vapor deposition. Ring blanks are placed in a spinning fixture and
subjected to abrasion against at least one curved abrasive surface.
For comfort rings, the inner surface is formed as a continuous curve.
For rings having inlaid malleable precious metal, the precious metal
is inserted in either a straight-wall or undercut wall. Ring blanks
having straight-wall grooves can be formed using conventional casting
processes. The precious metal is inlaid in the groove by one of
several processes, which may include hammering, rolling, or pressing.
For a preferred embodiment of the process, the inlaying process
involves laser welding of joints and burnishing of the inlaid metal,
and cutting the inlaid metal in a lathe to about the level of the
mouth of the groove.
Patent Claims
What is claimed is:
1. A method of method for manufacturing finger rings, bracelets,
earrings, and other annular body jewelry from sintered, or cemented,
composite materials comprising at least one metal carbide and a
metallic binder, comprises the steps of: placing an annular blank
of sintered material in a spinning fixture; and abrading the annular
blank against at least one curved abrasive surface so that the annular
blank acquires a curved surface about its circumference.
2. The method of claim 1, which further comprises the steps of:
providing an annular blank having at least one annular groove therein
on an outer surface thereof; forcing a piece of precious metal wire
into each groove, beginning at one end thereof and continuing to
the opposite end thereof so that both ends of the precious metal
wire adjoin one another; and removing excess precious metal to the
level of the outer surface of the blank.
3. The method of claim 2, which further comprises the step of joining
together the ends of the precious metal wire.
4. The method of claim 2, which further comprises the step of burnishing
the precious metal in the groove.
5. The method of claim 2, wherein the precious metal wire is hammered
into the groove.
6. The method of claim 2, wherein the precious metal wire is rolled
into the groove.
7. The method of claim 1, which further comprises the steps of:
providing an annular blank having at least one annular groove therein
on an outer surface thereof; forming an endless hoop of precious
metal wire for each annular groove; pressing an endless hoop into
each groove using a radial crimping/swaging machine; and removing
excess precious metal to the level of the outer surface of the blank.
8. The method of claim 7, which further comprises the steps of:
undercutting the walls of the groove with an abrasive tool prior
to pressing an endless hoop into an annular groove.
9. The method of claim 1, wherein the annular blank is subjected
to a thin film deposition process selected from the group consisting
of physical vapor deposition, chemical vapor deposition and plasma-assisted
chemical vapor deposition, in which a coating selected from the
group consisting of titanium nitride and diamond like carbon is
applied thereto.
10. A method for manufacturing finger rings, bracelets, earrings,
and other annular body jewelry from sintered, or cemented, composite
materials comprising at least one metal carbide and a metallic binder,
comprises the steps of: providing an annular blank having at least
one annular groove therein on an outer surface thereof; forcing
a piece of precious metal wire into each annular groove; and removing
excess precious metal to the level of the outer surface of the blank.
11. The method of claim 10, which further comprises the step of
laser welding together the ends of the precious metal wire.
12. The method of claim 10, which further comprises the step of
burnishing the precious metal in the annular groove.
13. The method of claim 10, wherein the precious metal wire is
hammered into the annular groove.
14. The method of claim 10, wherein the precious metal wire is
rolled into the annular groove.
15. The method of claim 10, wherein: the precious metal wire is
formed into an endless hoop for each annular groove; and an endless
hoop is pressed into each annular groove using a radial crimping/swaging
machine.
16. The method of claim 10, which further comprises the steps of:
undercutting the walls of the groove with an abrasive tool prior
to forcing a piece of precious metal wire into each annular groove.
17. A method for manufacturing finger rings, bracelets, earrings,
and other annular body jewelry from sintered, or cemented, composite
materials comprising at least one metal carbide and a metallic binder,
comprises the steps of: providing an annular blank having an annular
groove therein on an outer surface thereof; forming an endless hoop
of precious metal; pressing the endless hoop into the groove using
a radial crimping/swaging machine; and removing excess precious
metal to the level of the outer surface of the blank.
18. The method of claim 17, which further comprises the steps of
undercutting the walls of the groove with an abrasive tool while
the blank is chucked in the spinning fixture, and before the precious
metal hoop is forced into the groove.
19. The method of claim 17, wherein the annular blank is subjected
to a thin film deposition process selected from the group consisting
of physical vapor deposition, chemical vapor deposition and plasma-assisted
chemical vapor deposition, in which a coating selected from the
group consisting of titanium nitride and diamond like carbon is
applied thereto.
20. The method of claim 17, which further comprises the steps of:
securing the annular blank in a spinning fixture; abrading the annular
blank against at least one curved abrasive surface so that the annular
blank acquires a curved surface about its circumference.
Patent Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates generally to articles manufactured
from sintered composite materials and methods for their manufacture.
The sintered composite materials generally comprise, as the principal
component, very hard powdered materials with high melting points,
such as tungsten carbide, silicon carbide, aluminum oxide and ceramic
materials, in combination with a much smaller amount of a softer
binder metal, such as nickel, cobalt, palladium, platinum, ruthenium,
iridium and gold, or alloys thereof, which has a lower melting point.
[0003] 2. History of the Prior Art
[0004] For millennia, jewelry has been fabricated from soft metals,
such as gold, silver and platinum, which are malleable, as well
as castable and fusible at relatively low temperatures. Unfortunately,
soft metals have very little resistance to abrasion. Thus, relief,
detail and edges of soft metal jewelry tend to wear rapidly. This
is particularly true if the jewelry is worn so that it comes in
contact with hard objects and abrasive surfaces and particles.
[0005] Sintered, or cemented, composite materials comprising at
least one metal carbide and a metallic binder have long been used
for the manufacture of cutting tools as a result of their incredible
hardness and durability. Such materials are made, using conventional
well-known powder metallurgy, by bonding hard tungsten, tantalum,
titanium, or chromium nitride particles with one or metals such
as iron, cobalt, and nickel. The carbide particles, which are typically
about 20-150 .mu.m in size, generally comprise between 75 and 85
percent, by weight of the cemented material. Nitrides and carbonitrides
of the same metals may also be used as hard particles in cemented
materials. Cemented materials may also be formed using a combination
of two or more types of hard particles and binder metals such as
ruthenium, rhodium, palladium, platinum, silver and gold.
[0006] A composite material is manufactured, for example, by mixing
tungsten carbide powder, tantalum carbide powder, cobalt powder
and nickel powder according to a predertermined alloy composition,
molding the material powder of mixed alloy composition by pressing
the powder, and finally sintering the obtained molded pieces.
[0007] The major challenge of fabricating articles made of cemented
metal carbides is that of finishing the raw sintered components.
Because the molded pieces are formed using a high-pressure press,
complex shapes may be impossible to fabricate and dimensional precision
may be difficult or impossible to achieve directly. For example,
products having shapes that can be formed in one axis direction
only can be formed by die compaction. However, even if a cold isostatic
press (CIP) technique is used to form three-dimensional shapes,
high precision generally cannot be achieved because the items are
molded inside rubber molds.
[0008] As a consequence of the need for more durable jewelry, jewelry
manufacturers began fabricating watch cases and bands from cemented,
or sintered, metal carbides, several decades ago. These early pieces
were obtained using conventional processes, whereby relatively simple
shapes formed by normal powder metallurgy methods were subjected
to secondary machining, diamond grinding and electrical discharge
operations to realize the complicated shapes required for watch
cases and watch band pieces, which typically have curved surfaces,
small holes and mirror-polished surfaces.
[0009] Accordingly, U.S. Pat. No. 5,403,374 discloses a process
for manufacturing an exterior part for a watch having a three-dimensional
curved surfaced and a small hole, without applying secondary machining
operations.
[0010] The manufacturing of composite jewelry has expanded from
watches to annular items. U.S. Pat. No. 6,062,045 discloses a finger
ring having five facets having surface angles within a range of
from 1 to 40 degrees. A related U.S. Pat. No. 6,553,667, discloses
a system, apparatus and method for making composite jewelry items,
such as finger rings, bracelets, earrings, body jewelry and the
like. The focus of the patent is multiple methods of manufacture,
the first of which includes the steps of preheating an annular substrate,
contacting a depression in a surface of the substrate with a second
material, heating the second material at a point contact with the
substrate, causing the second material to liquify and flow into
the depression, and moving the point of contact along the depression
while continuously feeding the second material and heating the second
material at the point contact with the substrate to cause it to
substantially fill the depression. The second method includes the
steps of providing an annular composite article having an annular
groove therein, forming a seamless ring from a metal wire that slides
over the annular composite article, placing the annular composite
article on a mandrel, and forcing the ring into the groove with
a collet. The methods covered by this patent are costly and not
particularly adapted to mass production.
[0011] What is needed is a simplified process for manufacturing
finger rings, bracelets, earrings, body jewelry and the like, which
are more suited to high volume low-cost production.
SUMMARY OF THE INVENTION
[0012] The present invention includes a method for manufacturing
finger rings, bracelets, annular earrings, annular body jewelry
and the like, which have at least one curved surface, from sintered,
or cemented, composite materials comprising at least one metal carbide
and a metallic binder. The annular jewelry piece may be inlaid with
a precious metal and/or it may be subjected to a physical vapor
deposition (PVD), chemical vapor deposition (CVD), or plasma chemical
vapor deposition (PCVD) process in order to deposit thereon either
a metal compound, such as titanium nitride, or a diamond-like carbon
compound.
[0013] For all rings which are the subject of the present invention,
the ring blanks are placed in a spinning fixture and subjected to
abrasion against at least one curved abrasive surface. For comfort
rings, the inner surface is formed as a continuous curve.
[0014] For rings having inlaid malleable precious metal, the precious
metal is inserted in either a straight-wall, dovetail, or notched
groove. The precious metal is inlaid in the groove by one of several
processes, which may include hammering, rolling, or pressing. For
embodiments of the process involving hammering and rolling of the
inlay into the groove, the inlaying process may include the laser
welding of joints and removal of any excess inlaid metal above the
level of the mouth of the groove with a cutting tool affixed to
a lathe in which the ring has been rotatably chucked. As an alternative
to laser welding of the joint, the may be tack welded, torch welded,
or soldered, or the precious metal may be burnished and subsequently
cut back with a cutting tool. If the precious metal is inlaid in
a groove of either rectangular or dovetail cross section, a malleable
precious metal wire of generally rectangular cross section may be
used. For a dovetail or notched groove, it is necessary to deform
the precious metal wire as it is hammered, rolled or pressed into
the groove so that it expands to fill the slightly wider space below
the mouth of the groove. For the straight-wall groove of rectangular
cross section the wire may also be hammered, pressed or rolled in
order to secure a tighter fit of the precious metal against the
sidewalls of the groove.
[0015] The preferred method for inlaying a ductile metal in a groove
involves the use of a press. The inlay band is formed as a ring
either by laser welding the ends of a looped wire of rectangular
cross section, or by stamping. The inlay ring is then pressed into
the groove using a circular press. Any excess metal is then removed
with a cutting tool in combination with a lathe.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 is an isometric view of a finger ring blank after
a groove and facets have been ground on the outer surface and a
comfort surface has been ground on the inner surface thereof;
[0017] FIG. 2 is a cross-sectional view of the ring blank of FIG.
1, taken through its axis of symmetry;
[0018] FIG. 3 is a cross-sectional view of a ring blank similar
to that of FIG. 1, but having a dovetail groove therein;
[0019] FIG. 4 is a cross-sectional view of a ring blank similar
to that of FIG. 1, but having a notched groove therein;
[0020] FIG. 5 is an isometric view of a precious metal strip which
has been formed into a hoop, but having a gap between the two ends
thereof;
[0021] FIG. 6 is an isometric view of the precious metal strip
of FIG. 5 following closing of the gap;
[0022] FIG. 7 is an isometric view of the precious metal strip
of FIG. 6 following the laser welding of the abutting ends;
[0023] FIG. 8 is an isometric view of the assembly comprising the
ring blank of FIG. 1 and the precious metal hoop of FIG. 7, the
latter having been slipped over the former so that it is positioned
above the groove of the blank;
[0024] FIG. 9 is a front elevational view of the radial compression
head of a hydraulic crimping and swaging machine, in which the ring
and hoop have been positioned on a mandrel;
[0025] FIG. 10 is a cross-sectional view of the assembly of FIG.
8, but with the notched groove of FIG. 4, taken through its axis
of symmetry;
[0026] FIG. 11 is a cross-sectional view of the assembly of FIG.
10 following the compression of the hoop in the head of the crimping
and swaging machine so that it is positioned within the groove of
the ring blank;
[0027] FIG. 12 is a cross-sectional view of the assembly of FIG.
11 following further compression in the head of the crimping and
swaging machine so that the hoop is squeezed into the notches of
the groove of the ring blank;
[0028] FIG. 13 is a side elevational view of a ring blank secured
on the mandrel of a rolling machine, showing a precious metal strip
being rolled into the groove in the ring blank;
[0029] FIG. 14 is a side elevational view of a ring blank secured
on the mandrel of a hammering machine, showing a precious metal
strip being hammered into the groove in the ring blank;
[0030] FIG. 15 is a cross-sectional view of a ring blank secured
within a chuck and showing a process used to grind the comfort surface
inside the ring blank;
[0031] FIG. 16 is a cross sectional view of the ring blank of FIGS.
1 and 2 after its mounting on a mandrel and following the grinding
of a notch in one sidewall of the groove thereof; and
[0032] FIG. 17 is a cross-sectional view of the ring blank of FIG.
16 following the grinding of a notch in the other sidewall of the
groove thereof.
DETAILED DISCLOSURE OF THE INVENTION
[0033] The method for manufacturing finger rings, bracelets, annular
earrings, annular body jewelry and the like from sintered, or cemented,
composite materials comprising at least one metal carbide and a
metallic binder will now be described in detail with reference to
the attached drawing figures.
[0034] There are multiple aspects of the present invention. One
involves forming at least one curved surface on the sintered composite
material blank. Another involves the process of inlaying a precious
metal in a groove in the sintered composite material blank using
pressing, rolling or hammering. Still another involves subjecting
the sintered composite material blank to a chemical vapor deposition
process in order to deposit thereon a layer of nonallergenic material
such as titanium nitride or diamond-like carbon. Yet another involves
the grinding of notches in inlay grooves for improved anchoring
of the precious metal inlay. These various aspects of the invention
will now be described in detail with reference to the attaching
drawing figures.
[0035] Referring now to FIG. 1, an annular finger ring blank 100
made of sintered composite material has a pair of angled conical
facets 102, an annular groove 103, and an interior comfort surface
101.
[0036] Referring now to FIG. 2, the finger ring blank 100 is shown
in a cross-sectional view, which shows the parallel, vertical walls
201 of annular groove 103 and the curved interior comfort surface
101.
[0037] Referring now to FIG. 3, the finger ring blank 100 of FIGS.
1 and 2 has been modified so that the parallel, vertical walls 201
thereof have been replaced with slanted walls 302, which form a
dovetail groove 301. The dovetail groove ensures that precious metal
inlaid therein will be securely affixed to the ring. As a practical
matter, it is very difficult to grind the slanted walls of a dovetail
groove. Thus, the ring blank shown in FIG. 4 is a more practical
design.
[0038] Referring now to FIG. 4, the finger ring blank 100 of FIGS.
1 and 2 has been modified so that the parallel, vertical walls 201
thereof have been replaced with notched vertical walls 402. The
resulting groove 401 functions almost as well as, and is much more
manufacturable than the dovetail groove 301. The method of forming
the notched groove 401 will be subsequently disclosed.
[0039] FIGS. 5 through 12 depict the process used to form and press
a precious metal hoop into the groove of a ring blank 300.
[0040] Referring now to FIG. 5, a precious metal strip 501, which
may be gold, silver, platinum or other precious ductile metal, has
been formed into a hoop, but having a gap between the two ends 502A
and 502B thereof.
[0041] Referring now to FIG. 6, the gap between the two ends 502A
and 502B of precious metal strip 501 has been closed in preparation
for welding.
[0042] Referring now to FIG. 7, the two ends 502A and 502B of precious
metal strip 501 have been laser welded together to form an endless
hoop 701. The laser welding step may be replaced with a tack welding,
torch welding or soldering step. An endless hoop may also be produced
in a number of other ways, which include stamping and casting.
[0043] Referring now to FIG. 8, the precious metal hoop 701 of
FIG. 7 has been slipped over a sintered composite material ring
blank 100, 200 or 300 so that the precious metal hoop 701 is positioned
directly above the groove 103, 301 or 401, respectively.
[0044] Referring now to FIG. 9, the assembly of FIG. 8 is shown
mounted on a mandrel 905 that is axially positioned within the head
901 of a Finn-Power crimping and swaging machine. The head 901 has
eight radially movable collet members 902. The collet members are
movable via hydraulic pressure applied to hydraulic fittings 903
via hydraulic lines 904. Although the machine was designed especially
for crimping or swaging tubular collars used to secure fittings
to the end of flexible lines and tubes, the machine can be used
to compress or squeeze the precious metal hoop 701 into the groove
of a ring blank 100 200 or 300.
[0045] Referring now to FIG. 10, the assembly of FIG. 8 is shown
before the compression process is effected in the Finn-Power crimping
and swaging machine.
[0046] Referring now to FIG. 11, the precious metal hoop 701 has
been compressed so that its diameter has shrunk to the extent that
it is now annularly positioned within the groove 103, 301 or 401.
As an example of a preferred embodiment of the invention, groove
401 is actually shown in this drawing figure.
[0047] Referring now to FIG. 12, compression of the precious metal
hoop 701 is continued until metal from the hoop 701 has squeezed
into the notches of notched walls 402, thereby securing the metal
hoop in the groove 300. Any excess inlaid metal above the level
of the mouth of the groove may be removed with a cutting tool affixed
to a lathe in which the ring has been rotatably chucked.
[0048] Referring now to FIG. 13, a first alternative inlay method
is shown, whereby a precious metal strip 1302 is rolled into the
groove 103, 301 or 401 of a ring blank 100, 200 or 300, respectively.
The ring blank 100, 200 or 300 is positioned on a mandrel 1301 that
is rotatable about a central axis 1304. As the ring blank 100, 200
or 300 is rotated on mandrel 1301, a roller 1303 pressed against
the ring blank 100, 200 or 300 and forces the precious metal strip
302 into the groove 103, 301 or 401. The ends of the precious metal
strip may be laser welded together or the precious metal strip 1302,
once it is inlaid in the groove 103, 301 or 401, may be burnished
in order to conceal the joint where the ends of the precious metal
strip 302 meet.
[0049] Referring now to FIG. 14, a is a second alternative inlay
method is shown, whereby a precious metal strip 1302 is hammered
into the groove 103, 301 or 401 of a ring blank 100, 200 or 300,
respectively. The ring blank 100, 200 or 300 is positioned on a
mandrel 1301 that is rotatable about a central axis 1304. As the
ring blank 100, 200 or 300 is rotated on mandrel 1301, a reciprocating
hammer head 1401 forces the precious metal strip 302 into the groove
103, 301 or 401. The ends of the precious metal strip may be laser
welded together or the precious metal strip 1302, once it is inlaid
in the groove 103, 301 or 401, may be burnished in order to conceal
the joint where the ends of the precious metal strip 302 meet.
[0050] Referring now to FIG. 15, a ring blank 300 is secured by
jaws 1502 within a chuck 1501 that spins about a central axis 1503.
A grinding wheel 1504 having a concave cross-sectional profile spins
about an axis of symmetry 1505. The grind wheel 1504 grinds the
comfort surface 101 in a grinding operation.
[0051] Referring now to FIGS. 16 and 17, the method of grinding
the vertical sidewalls 201 of groove 103 (see FIG. 2) to form a
groove 401 having notched sidewalls 402 (see FIG. 4) is shown. The
ring blank 100 is secured on a mandrel 1601 that spins on a ring
rotation axis 1602. A grinding wheel 1603 having diamond grit embedded
therein is rotated on a grinding axis 1604 that makes an acute angle
with and preferably intersects the ring rotation axis 1602. As shown
in FIGS. 16 and 17, the notches may be cut one at a time by either
reversing the ring for the second notch or in each wall 201 by simply
reversing the ring by moving the tool to the other side.
[0052] Referring now to FIG. 18, the notches in the sidewalls 201
of groove 103 may be ground simultaneously with the equipment set
up as shown and employing two grind wheels 1603A and 1603B.
[0053] Prior to the metal inlay process, the ring may be subjected
to a physical vapor deposition (PVD), chemical vapor deposition
(CVD), or plasma chemical vapor deposition (PCVD) process in order
to deposit thereon either a metal compound, such as titanium nitride,
or a diamond-like carbon compound. Titanium nitride is a gold coloured
ceramic coating having a face-centered cubic crystal structure that
is applied, most typically, by physical vapor deposition (PVD).
Titanium nitride is characterized by extreme density, non-porosity,
extreme hardness (approximately 85 Rc) that is greater than that
of carbide compounds, and a low coefficient of friction. As it is
a highly inert compound, it has excellent chemical resistance and
hypoallergenicity. It is typically applied in thicknesses ranging
from about 3 to 12 microns. Deposited titanium nitride films can
be subjected to temperatures of up to 600.degree. C. without damage,
are highly conformal (i.e., the deposited film follows the contour
of the substrate), able to withstand high temperatures, and form
an outstanding bond to the substrate that will not blister, flake,
or chip.
[0054] Titanium nitride coatings may be applied by PVD, CVD or
PCVD. Each of these processes will be briefly addressed. Physical
Vapor Deposition, or PVD, involves the atom-by-atom, molecule-by-molecule,
or ion deposition of various materials on solid substrates in vacuum
systems. Two types of physical vapor deposition are currently used.
Thermal evaporation uses the atomic cloud formed by the evaporation
of the coating material in a vacuum environment to coat all the
surfaces in the line of sight between the substrate and the target
(source). Sputtering, on the other hand, applies high-technology
coatings such as ceramics, metal alloys, organic and inorganic compounds
by connecting the workpiece and the substance to a high-voltage
DC power supply in an argon vacuum system (10-2-10-3 mmHg). A plasma
is established between the substrate (workpiece) and the target
(donor) and transposes the sputtered off-target atoms to the surface
of the substrate. When the substrate is non-conductive, radio-frequency
(RF) sputtering is used.
[0055] Chemical Vapor Deposition, or CVD, is capable of producing
thick, dense, ductile, and good adhesive coatings on metals and
non-metals such as glass and plastic. Contrasting to the PVD coating
in the "line of sight", the CVD can coat all surfaces
of the substrate.
[0056] Plasma-Assisted Chemical Vapor Deposition, or PCVD, is a
technique for producing hard wear-resistant surface coatings on
tools and wear parts. The difference between Plasma-Assisted CVD
and conventional CVD lies mainly in a process temperature of about
500.degree. C., as opposed to the 1000-1100.degree. C. temperatures
of a conventional CVD process.
[0057] Diamond-like-carbon (DLC) is an amorphous coating with an
extremely low coefficient of friction and extreme hardness. DLC
coatings are typically applied by either CVD or PCVD processes.
DLC CVD processes are generally limited to materials which will
not soften at temperatures within a range of 700-750.degree. C.
Cemented carbides certainly fall in this category. The PCVD DLC
coating process can be performed at lower temperature than the DLC
CVD processes.
[0058] As the patent and technical literature is replete with processes
for PVD, CVD and PCVD for titanium nitride coatings, as well as
processes for CVD and PCVD for diamond-like carbon coatings, no
attempt will be made to provide detailed coverage, as the processes
themselves are considered prior art. The inventive aspect is the
coating of the cemented carbide ring blanks with those coatings
in order to enhance their appearance, provide a more wear resistant
surface, and render them hypoallergenic.
[0059] Although only several embodiments of the present invention
have been disclosed herein, it will be obvious to those having ordinary
skill in the art that changes and modifications may be made thereto
without departing from the scope and spirit of the invention as
hereinafter claimed.
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