GB2041427A

GB2041427A - Insert for tool wear surfaces and method of manufacture

Info

Publication number: GB2041427A
Application number: GB7935118A
Authority: GB
Original assignee: NL Industries Inc
Current assignee: NL Industries Inc
Priority date: 1978-11-01
Filing date: 1979-10-10
Publication date: 1980-09-10
Also published as: FR2440245A1; GB2041427B; NL7907924A; FR2440245B1; CA1123822A; NO793434L

Abstract

Abrasion resistant inserts incorporating hard particles, particularly diamonds, for use in the wear surfaces of a tool body, e.g. a drill string stabilizer, have generally been relatively costly to manufacture. This invention provides an insert (10) including a body portion having pockets (40, 44) in its exposed face (12) and a solid matrix (50) formed into each pocket by powder metallurgy. Each matrix includes at least one hard, abrasion resistant particle (52), for example, a diamond. A method of manufacturing an insert includes the steps of filling the pockets in the body portion with carbide matrix powder (50) having a hard particle (52) disposed therein, placing a binder on the matrix powder and heating the matrix powder and binder to a temperature sufficient to melt the binder so that the binder infiltrates the matrix powder to form the solid matrix. <IMAGE>

Description

SPECIFICATION Insert for tool wear surfaces and method of manufacture The invention relates 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 diamonds.

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 resistance.

Inserts have been made from solid materials such as sintered tungsten carbide which are typically formed by well-known powder metallurgy techniques. It has also been proposed to include hard particles, for example, diamonds, into the sintered carbide at the exposed face of the insert to form an insert having improved abrasion resistance characteristics. However, the manufacture of such inserts, especially those including diamonds, has proven extremely costly.

In accordance with the present invention there is provided 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 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 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 steel. Furthermore, the body may comprise an inner body coated with a coating such as titanium carbonitride.

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 surface which comprises the steps of: (a) filling the pocket with a matrix powder having at least one hard particle disposed within the matrix powder; (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. Pockets are formed in the exposed surface of the insert for holding 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 may be filled with a carbide matrix powder having at least one hard particle disposed therein.

The matrix powder is furnaced within the pocket by powder metallurgy techniques. One aspect of this feature is that a binder such as a copper alloy may infiltrate the matrix powder 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 may be 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 following more detailed description.

Embodiments of the invention will now be described by way of example and with reference to the accompanying drawings, in which: Figure 1 is a plan view of the insert body portion.

Figure 2 is a section view taken substantially along line 2-2 of Fig. 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 Fig. 3 after furnacing.

Figure 5 is a view similar to Fig. 4 showing a pocket containing a solid matrix with two diamonds disposed in layers.

Figure 6 is a view similar to Figs. 4 and 5 showing a pocket containing a solid matrix with a large number of small diamonds.

Figure 7 is a view similar to Figs. 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 which utilizes different types of inserts, some of which are manufactured in accordance with the present invention.

The preferred embodiment of the present invention will now be described with reference to Figs. 1-4. Fig. 1 is a top view of the insert body utilized in accordance with the present invention. Insert body 10 is substantially cylindrical in shape and includes a planar exposed surface 1 2 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 1 8 and a beveled ring surfaces 22 and 23 connecting the sidewall to the base. Sidewall 1 6 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, may be deformed into the serrations to form an integral lock.

As best shown in Fig. 2, an upper tapered ring portion 34 and a circular lip 36 are provided where exposed surface 1 2 meets sidewall 1 6.

In the illustrated embodiment, exposed surface 1 2 includes a ring of five pockets 40 which are symmetrically disposed along a circle concentric with the outer surface of body 1 0. 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 integrity of the body 10 is not affected.

Fig. 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 tungsten 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 particle. In a preferred embodiment, the binder 56 is a copper alloy, for example, No. 1 6 binder manufactured by Entectic Cor poration. In the embodiment illustrated in Fig.

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 substantially 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 approximately 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 Figs. 3 and 4 is approximately 0.08 inch on a side.

Therefore, it can be seen that the upper face 57 of diamond 52 occupies a major portion of the exposed portion of pocket 44. In this case, is desired that diamond face 57 occupy an area in excess of 1/2 of the exposed pocket. The primary purpose of the solid matrix 50 is to serve as the continuous phase for holding the hard particle, e.g., diamond 52, in place. Therefore, it will be desirable in many applications to utilize 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 Figs. 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 present invention will now be described with further reference to Figs. 1-4. As stated previously, the insert body may be a cemented carbide body formed by powder metallurgy from, for example, a tungsten carbide powder. The body may also be formed from other powders, e.g., other carbide powders, or from other materials such as tool steel. In a particular method of manufacturing an insert body for use with the present invention, 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 is next placed in a dewaxing furnace to drive off the wax at approximately 800"F and then sintered at 3000-3200"F whereby the binder, for example, cobalt 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.It should be pointed out that the body portion t0 may be made by numerous techniques, including solid-phase or liquid-phase sintering powder metallurgy techniques, and that the primary requirement of the body portion is that it have acceptable abrasion resistant characteristics, 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 other 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 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 particles. In a preferred manner of practicing in the invention, the binder is selected as a copper alloy No. 1 6 binder manufactured by Entectic Corporation. It is preferable that the binder be one that will melt at a temperature below approximately 2200"F since natural diamonds will sustain structural damage when the diamond is subjected to temperatures essentially in excess of 2200"F. 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, preferably 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 1 2. 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 lip 36. An alternative 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 2200"F when diamonds are used to constitute all or a part of the hard particles. In a preferred method of practicing the invention with diamonds utilized as the hard particles, the insert pockets containing a tungsten carbide powder matrix is furnaced for ten minutes at 2150"F 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 1 650 F to 2200"F without appreciable damage to the structure of natural diamonds.Furthermore, it will be appreciated that with the use of other hard particles the furnacing cycle may take place within a temperature range above 2200'F.

During furnacing it has been found that the hard particles, 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 fixturing means on the hard particles during furnacing.

A first alternative embodiment of an insert constructed in accordance with the present invention will be described with reference to Fig. 5. Fig. 5 illustrates a pocket 44 formed in the insert body wherein a pair of natural, substantially cube-shaped 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 1 2 will gradually erode. During this erosion the matrix material 50 within 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 Fig. 5 includes only one hard particle, a substantially cube-shaped diamond, in each layer.

Fig. 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" illustrated in Fig. 6 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 Fig. 7 wherein a single diamond 70 is disposed within the matrix so as to protrude above the exposed surface 1 2. This embodiment 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 0.1 0 inch it has been found desirable to have the diamond protrude approximately 0.06 inch.

It will be appreciated that inserts manufactured in accordance with the present invention will have application in numerous tools. For example, as shown in Fig. 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 Fig. 7. It will be appreciated that the inserts found in areas A protrude above the stabilizer blade in order to effect cutting at the end portions 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 stabilizer blade surface as shown, for example, in Fig.

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.

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 applications 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 connection 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 the present invention. For example, the pockets may incorporate hard particles other than natural diamonds, e.g., synthetic polycrystalline 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. Typical commercial diamond shapes, e.g., round, tetragonal and cube, 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 variations are within the spirit and scope of the present invention.

Claims

1. An insert comprising: a body portion having at least one pocket formed in its exposed surface; and a matrix formed in said at least one pocket and being intimately bonded to the pocket walls, said matrix including at least one hard particle.

2. An insert as claimed in claim 1 wherein said hard particle is located proximate the exposed surface.

3. An insert as claimed in claim 1 or claim 2, wherein said hard particle is a natural diamond.

4. An insert as claimed in claim 1 wherein said matrix includes a plurality of hard particles arranged in layers.

5. An insert as claimed in claim 4, wherein said particles are natural diamonds.

6. An insert as claimed in any preceding claim wherein said insert includes serrated sidewall surfaces facilitating press fitting of the insert into a mating opening in a wear surface.

7. An insert as claimed in claim 6, wherein said sidewall surfaces are cylindrical.

8. An insert as claimed in claim 7, wherein said body portion exposed surface includes a plurality of pockets disposed symmetrically along a circle concentric with the outside surface of the insert.

9. An insert as claimed in any preceding claim wherein said body portion is formed by powder metallurgy from cemented carbide composition.

10. An insert as claimed in claim 9, wherein said carbide composition comprises tungsten carbide.

11. An insert as claimed in claim 9 wherein said carbide composition comprises titanium carbide.

1 2. An insert as claimed in claim 9, wherein said carbide composition comprises vanadium carbide.

1 3. An insert as claimed in claim 9 wherein said carbide composition comprises a mixture of vanadium carbide and molybdenum carbide.

14. An insert as claimed in any of claims 1 to 8 wherein said body portion comprises tool steel.

1 5. An insert as claimed in any of claims 1 to 8 wherein said body portion comprises an inner body coated with a solid coating.

1 6. An insert as claimed in claim 1 5 wherein said coating comprises titanium carbonitride.

1 7. An insert substantially as hereinbefore described with reference to and as illustrated in Figs. 1 to 4, or any one of Figs. 5 to 7 of the accompanying drawings.

1 8. A member having a wear surface and an insert as claimed in any preceding claim for use as an abrasion resistant element when press fitted into the wear surface, the insert comprising a body portion sized to be a press fit in a mating opening in the wear surface, said body portion having an exposed surface which, after press fitting, substantially forms a continuation of the wear surface, said exposed surface having said at least one pocket formed therein; and said matrix being formed in said at least one pocket by powder metallurgy with the matrix forming an intimate contact with the pocket walls, and including said at least one hard particle.

1 9. A method of manufacturing an insert from an insert body having at least one pocket formed in its exposed surface, comprising the steps of: filling the pocket with a matrix powder having at least one hard particle disposed within the matrix powder; placing a binder proximate the matrix powder; and heating the matrix powder and binder to a temperature sufficient to melt the binder so that the binder infiltrates the matrix powder.

20. A method as claimed in claim 1 9 wherein said hard particle is a natural diamond.

21. A method as claimed in claim 19 or claim 20 wherein said hard particle is disposed within the matrix powder substantially flush with the body exposed surface.

22. A method as claimed in claim 1 9 or claim 20 wherein said hard particle is disposed within said matrix powder to protrude above the body exposed surface.

23. A method as claimed in claim 1 9 or claim 20 wherein a plurality of hard particles are disposed in layers within the matrix powder.

24. A method as claimed in any of claims 1 9 to 23 of manufacturing an insert for press fitting into a mating opening in a wear surface, including the step of forming the insert body to have a substantially planar exposed surface which, after press fitting, substantially forms a continuation of the wear surface, the exposed surface being formed with said at least one pocket therein.

25. A method of manufacturing an insert, substantially as hereinbefore described with reference to Figs. 1 to 4, or any one of Figs.

5 to 7 of the accompanying drawings.