Note: Descriptions are shown in the official language in which they were submitted.
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BACKGROUND O~ THE INVENTION
1. Field of the Invention
The invention rela~es to abrasion resistant inserts for
incorporation into wear surfaces of tools, for example,
downhole oilfield tools such as drill string stabilizers.
In particular, the invention relates to inserts of the type
incorporating exposed or flush hard particles such as dia-
monds.
2. Description of the Prior Art
It is well known that the wear surfaces of certain tools,
for example, downhole oil field tools such as stabilizers,
drill bits and roller reamers, may be provided with wear
resistant inserts that reduce abrasive wear of the tool~
The inserts are usually press fit into openings in the tool
body to provide areas having exceptional abrasion re~istance.
Inserts have been made from solid materials such as sin-
tered tungsten carbide which are typically formed by well-
known powder metallurgy techniqùes. It has also been proposed
to include hard particles, for example, diamonds, into the
20 sintered carbide at the exposèd face of the insert to form an
insert having improved abrasion resistance characteristics.
~owever, the manufacturé of such inserts, especially those
including diamonds, has proven extremely costly~
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SUMMARY O~ THE INVENTION
In accordance with the present invention there is pro-
vided a novel insert for incorporation into the wear surface
of a tool body. In a particular embodiment, the insert
includes:
(a) a body portion having at least one pocket
formed in its exposed surface; and
~b) a solid matrix formed in said at least one
pocket and being intimately bonded to the
1~ pocket walls, said matrix including at
least one hard particle.
The hard particle in each pocket may be a natural diamond
which may be disposed substantially flush with the exposed
surface of the insert body or may protrude from the exposed
surface to effect cutting. A plurality of hard particles may
be disposed in layers within each pocket. In a preferred
embodiment, the body portion is formed as a cylinder having
serrated edges facilitating press fitting of the body into a
mating opening in the wear surface of a tool. According to
2~ this preferred embodiment, the exposed surface of the insert
has a plurality of pockets disposed symmetrically along a
circle concentric with the outer surface of the insert.
The body portion may be formed by powder metallurgy from
a carbide powder such as tungsten carbide or may be formed
from other materials such as tool ~teel. Furthermore, the
body may comprise an inner body coated with a coating such as
titanium carbonitride.
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3822
In accordance with the present invention there is also
provided a novel method of manufacturing an insert from an
insert body having at least one pocket in its exposed sur-
face which comprises the steps of:
(a) filling the pocket with a matrix powder
having at least one hard particle disposed
within the matrix pouder;
(b) placing a binder proximate the matrix
powder; and
~ (c) heating said matrix powder and binder to
a temperature sufficient to melt the
binder so that the binder infiltrates
the matrix powder.
Accordingly, it is a principle feature of the present
invention to provide an insert adapted for press fitting into
an opening in the wear surface of a tool to enhance the wear
resistance of the tool surface. The insert may comprise a
relatively abrasion resistant body portion adapted for press
fitting into a mating opening in the tool wear surface. Poc-
~ kets are formed in the exposed surface of the insert forholding hard particles, such as diamonds, in place to enhance
the abrasion resistance characteristics of the wear surface.
It is a further feature of the present invention to
provide an insert having an exposed surface with pockets
wherein the pockets are filled with a carbide matrix powder
having at least one hard particle disposed therein. The
matrix powder is furnaced within the pocket by powder metal-
lurgy techniques. One aspect of this feature is that a
binder such ~s a copper alloy may infiltrate the matrix powder
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~L~IL23~3Z2
during the furnacing operation to provide a solid matrix in
intimate contact with the walls of the pocket.
It is still a further feature of the present invention
to provide a method of manufacturing an insert wherein the
insert body pockets are filled with a carbide matrix powder
having diamonds disposed therein and the matrix powder and
binder are furnaced at a temperature below that which causes
thermal damage to the diamonds.
Still further advantages and meritorious features of
the present invention will become apparent from the follow-
ing more detailed description.
Z382~
BRIEF DESCRIPTION OF T~E DRAWINGS
Figure 1 is a plan view of the insert body portion.
Figure 2 is a section view taken substantially along
line 2-2 of Figure 1.
Figure 3 is an enlarged view of one pocket in-the insert
body showing the carbide matrix powder, a diamond and the
binder in place prior to furnacing.
Figure 4 shows the pocket of Figure 3 after furnacing.
Figure 5 is a view similar to Figure 4 showing a pocket
containing a solid matrix with two diamonds disposed in layers.
Figure 6 is a view similar to Figures 4 and 5 showing a
pocket containing a solid matrix with a large number of small
diamonds.
Figure 7 is a view similar to Figures 4, 5 and 6 showing
a pocket containing a solid matrix with a diamond protruding
above the matrix to effect cutting.
Figure 8 is a view of a blade type stabilizer whic~
utili~es different types of inserts, some of which are manu-
factured in accordance with the present invention.
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DETAILED D~SCRIPTION OF THE PREFERRED EMBODIMENT
The preferred embodiment of the present invention will
now be described with reference to Figures 1-4. Figure 1 is
a top view of the insert body utilized in accordance with
the present invention. Insert body 10 is substantially cylin~
drical in shape and includes a planar exposed surface 12 which
is adapted to substantially form a continuation of the wear
surface of a tool when the body 10 is press fit into a mating
opening in the tool wear surface. Body 10 further includes
cylindrical sidewall portion 16, a substantially flat base 18
and a beveled ring surfaces 22 and 23 connecting the sidewall
to the base. Sidewall 16 is preferably formed with a serrated
edge comprising protrusions 26 and recesses 30. The serrations
facilitate the press fitting of the insert body into a mating
opening in the wear surface whereby the material of the tool
body, typically steel t may be deformed into the serrations to
form an integral lock.
As best shown in Figure 2, an upper tapered ring portion
34 and a circular lip 36 are provided where expo~ed surface 12
meets sidewall 16.
In the illustrated embodiment, exposed surface 12 includes
a ring of five pockets 40 which are symmetrically disposed
along a circle concentric with the outer surface of body 10.
An inner pocket 44 is formed at the center of the concentric -
circles. The spacing between the pockets and the configuration
and location of the pockets are not critical provided there is
ample space between the pockets so that the structural integ-
rity of the body 10 is not affected.
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~Li23~32Z
Figure 3 illustrates a single pocket 44 filled with a
carbide matrix powder 50, a single, substantially cube-shaped
diamond 52 and covered by a binder 56 prior to furnacing of
the matrix powder. In a preferred manner of practicing the
invention, the matrix powder is a t~ngsten carbide powder.
Binder 56 is selected so that it melts before reaching the
maximum furnace temperature and thereby infiltrates the matrix
powder in the manner known in the art to form a solid matrix
that serves as the continuous phase for supporting the hard
10 particle. In a preferred embodiment, the binder 56 is a cop-
per alloy, for example, No. 16 binder manufactured by Entectic
Corporation. In the embodiment illustrated in Figure 3, the
hard particle contained within the matrix is a single natural
diamond 52 which may have a size on the order of 1/10 carat.
Diamond 52 is disposed within the matrix powder su~stantially
flush with the exposed surface 12.
In the illustrated embodiment, insert body 10 has a
diameter of approximately 9/16 inch and a height of approxi-
mately 3/8 inch. This is a standard sized insert for many
downhole oil field tool applications; however, other insert
sizes, e.g., 3/8 inch diameter, are utilized. Each pocket
40, 44 has a diameter of approximately 0.10 inch and a depth
which may vary but, as illustrated, is on the order of 0.20
inch. Diamond 52 illustrated in Figures 3 and 4 is approxi-
mately 0.08 inch on a side. Therefore, it can be seen that
the upper face 57 of diamond ~ occupies a major portion o~
the exposed portion of pocket 4~. In this case, is desired
that diamond face 57 occupy an area in excess o~ 1/2 of the
exposed pocket. The primary purpose of the sGlid matrix 50
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is to serve as the continuous phase for holding the hard
particle, e.g., diamond 52r in place. Therefore, it will be
desirable in many applications to utill~e a diamond having a
face that will occupy most of the exposed pocket surface, for
example, diamond faces occupying up to 90% of even more of
the pocket surface. It will be appreciated that irregular
shaped diamonds, particularly irregular shaped diamonds
having one substantially flat face, may be utilized in place
of more uniform cube-shaped diamonds. It will also be
appreciated that in the embodiment illustrated in Figures
1-4 the body 10 is considerably harder than solid matrix 50;
therefore, the enhanced abrasion resistant characteristics
are provided by the diamond face and not by the solid matrix
50.
A method of manufacturing an insert in accordance with
the pxesent invention will now be described with further
reference to Figures 1-4. As stated previously, the insert
body may be a cemented carbide body formed by powder metall-
urgy from, for example, a tungsten carbide powder. The body
may also be formed from other powders, e.g~, other carbide
powders, or rom other materials such as tool steel. In a
particular method of manufacturing an insert body for use
with the present inven-tion, the body 10 is manufactured by
conventional cold pressing and sintering powder metallurgy
techniques. More particularly, a tungsten carbide powder
including wax and a binder, for example, cobalt, are cold
pressed to shape in a steel dye. The body so formed is
next ejected from the dye and is held together at this point
by the wax. The body i5 next placed in a dewaxing furnace
to drive off the wax at approximately ~00F and then sintered
at 3000-3200F whereby the binder, for example, cobalt,
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becomes molten to fully densify the material. At this point,
the cemented carbide insert body 10, including pockets 40 and
44, is complete and ready to receive the matrix powder and
hard particles within each pocket. I-t should be pointed out
that the body portion 10 may be made by numerous -techniques,
including solid-phase or liquid-phase sintering powder metall-
urgy techniques, and that the primary requirement of the body
portion is that it have acceptable abrasion resistant charac-
teristics, acceptable compressive strength and reasonably high
hardness, for example, in the case of a cemented tungsten
carbide insert body, a hardness on the order of a Rockwell A
hardness index of 90. When body 10 is a cemented carbide body
formed by powder metallurgy, the powder may be othex than
tungsten carbide, for example, titanium carbide, vanadium
carbide, or a mixture of vanadium carbide and molybdenum
carbide. A further means of forming the body is to form the
body in two parts comprising an inner body coated with a
solid coating such as titanium carbonitride.
After the insert body 10 has been formed with pockets
such as pockets 40 and 44, a matrix powder such as tungsten
carbide matrix powder is placed within each pocket with a
selected number of hard particles disposed within the powder
at desired points. Preferably, the matrix powder is chosen
so that it will shrink during furnacing somewhat less than the
shrinkage of -the body so that the body will shrink around the
matrix powder~as it is densified to a solid matrix. The
matrix powder is chosen such that after furnacing it will
have good impact strength to prevent fractures and will have
good wear characteristics so that it will not wash out around
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` ~LZ3~322
the hard particles. In order to assure that the matrix powder
has properly settled within the pocket prior to furnacing, the
insert body may be vibrated.
A binder, for example a copper alloy, is next placed on
top of each pocket containing the matrix powder and hard par-
ticles. In a preferred manner of practicing in the invention,
the binder is selected as a copper alloy No. 16 binder manu-
factured by Entectic Corporation. It is preferable that the
binder be one that will melt at a temperature below approxi-
mately 2200F since natural diamonds will sustain structuraldamage when the diamond is subjected to temperatures essenti-
ally in excess of 2200F. A sufficient amount of binder should
be placed over each pocket so that when melted the binder will
fully infiltrate the matrix powder to give maximum infiltration
and maximum density of the final solid matrix. Therefore, pre-
ferably an excess of binder is placed above each pocket to
ensure maximum infiltration. The binder that melts and does
not infiltrate will remain on exposed surface 12. In order
to prevent excess melted binder from covering the sidewall 16,
a dam (not shown) or other means may be constructed around the
perphery of the tool body, for example, at llp 36. An alter-
native method of keeping the excess melted binder off of the
sidewalls is to coat the sidewall surfaces with a protective
coating such as STOP-OFF brand protective coating manufactured
by Wall Colmonoy of Detroit, Michigan.
Furnacing of the material within the insert pockets is
accomplished at a temperature below 2200F when diamonds are
used to constitute all or a part of the hard particles. In
a preferred method of practicing the invention with diamonds
.
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utilized as the hard particles, the insert pockets containing
a tungsten carbide powder matrix is furnaced for ten minutes
at 2150F utilizing the No. 16 Entectic copper alloy as a
binder. It will be appreciated that adequate infiltration of
certain binders with various matrix powders can be achieved
within a range of approximately 1650F to 2200F without
appreciable damage to the structure of natural diamonds. Fur-
thermore, it will be appreciated that with the use of other
hard particles the furnacing cycle may take place within a
10 temperature range above 2200F.
During furnacing it has been found that the hard par-
ticles, for example, diamonds, may tend to float within the
matrix powder as it is being infiltrated by the binder.
Therefore, it may be desirable to place a weight or other fix-
turing means on the hard particles during furnacing.
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ALTE~NATIVE EMBODIMENTS
A first alternative embodiment o~ an insert constructed
in accordance with the present invention will be described
with reference to Figure 5. Figure 5 illustrates a pocket 44
~ormed in the insert body wherein a pair of natural, substan-
tially cube-shapped diamonds 60, 62 are disposed in layers
within the matrix powder. It will be appreciated that during
use of tools having wear surfaces incorporating the inserts
of the present invention, the wear surface and the insert
exposed surface 12 will gradually erode. During this erosion
I0 the matrix material 50 withi`n the pockets will also wear down.
Therefore, it may be desirable in some applications to have
the hard particles within the pockets disposed in layers so
- that when the first layer is worn away another layer will be
present to slow the further erosion of the wear surface. It
will be appreciated that each layer within the pocket may
include more than one hard particles although the embodiment
illustrated in Figure 5 includes only one hard particle, a
substantially cube-shaped diamond, in each layer.
Figure 6 illustrates a second alternative embodiment of
the invention wherein a very large number of hard particles,
for example small diamonds 66, are disposed within the matrix.
The so-called "diamond impregnated matrix~ strated in
Figure ~ may be used in certain applications to give uniform
wear resistant characteristics to the matrix material from the
top to the bottom of the pocket.
A third alternative embodiment is illustrated in Figure
7 wherein a single diamond 70 is disposed within the matrix
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so as to protrude above the exposed surface 12. This embodi-
ment may be utilized where the tool into which the insert is
press fit is utilized to perform cutting. In one embodiment
with a pocket having a diameter of 0.10 inch it has been found
desirable to have the diamond protrude approximately 0.06 inch.
APPLICATIONS OF THE INVENTION
It will be appreciated that inserts manufactured in
accordance with the present invention will have application in
numerous tools. For example, as shown in Figure 8, a near-bit
stabilizer 80 may include three different kinds of inserts.
In the areas designated by reference character A, the inserts
on the stabilizer blades are formed with pockets having single
diamonds which protrude above the surface of the stabilizer
blade as shown, for example, in Figure ~. It will be appre-
ciated that the inserts fo~nd in areas A protrude above the
stabilizer blade in order to efect cutting at the end por-
tions of the blade.
The inserts located in the stabilizer blades in the areas
designated by reference character B include pockets having
single cube-shaped diamonds which lie flush against the stabi-
lizer blade surface as shown, for example, in Figure 4. The
inserts in areas B are intended to reduce abrasion without
effecting appreciable cutting.
The inserts located on the stabilizer blades in the area
designated by reference character C are conventional solid
tungsten carbide inserts having no hard particles. These
inserts reduce abrasive wear in area C but are not provided
with pockets for including hard particles such as diamonds.
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It will be appreciated by those skilled in the art that
inserts manufactured in accordance with the present invention
may be utilized on other types of drill string stabilizers,
on the gauge of drill bits, on roller reamers, and on tool
joints and other drill string components. It will also be
appreciated that the inserts may be used in mining applica~
tions anywhere there is a wear surface where wear is to be
reduced. In general, the invention has application for use
as an abrasion resistant element on any body having a surface
exposed to abrasive wear conditions.
While the present invention has been disclosed in connec-
tion with several illustrated embodiments, it will be apparent
to those skilled in the art that numerous modifications may be
made without departing from the spirit or scope of t~e present
invention. For example, the pockets may incorporate hard par-
ticles other than natural diamonds, e.g.,synthetic polycry-
stalline diamonds. Furthermore, it will be appreciated that
the shape of diamonds utilized within the pockets may be
selected according to the particular use of the insert. Typ-
ical commercial diamond shapes, e.g., round, tetragonal andcube, may be utilized as well as other shapes. Furthermore,
diamonds of different qualities may be used. Also, diamonds
having surfaces treated chemically or mechanically may be used
in certain applications. While it has been disclosed that
the inserts are ~press fit~ into openings in a wear surface,
it will be appreciated that the term ~press fit" is deemed
to include any means of forcibly inserting the insert into a
mating opening, for example, by hammering or by pressing at
variable forces. These and other ~arlations are within the
~ spirit and scope of the present invention.
