Boring or penetrating the earth – Bit or bit element – Specific or diverse material
Reexamination Certificate
1998-03-25
2001-02-27
Bagnell, David (Department: 3673)
Boring or penetrating the earth
Bit or bit element
Specific or diverse material
C076S108200, C076SDIG001, C076SDIG001, C175S428000, C175S434000
Reexamination Certificate
active
06193001
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a method for forming cutting elements and specifically to a method for forming cutting( elements having a non-uniform interface adjacent their cutting layers.
Cutting elements, such as shear cutters for rock bits, for example, typically have a body (or substrate) which has a cutting face. A cutting layer (sometimes referred to as a “cutting table”) is bonded to the cutting face of the body. The body is generally made from cemented tungsten carbide (sometimes referred to simply as “tungsten carbide” or “carbide”), while the cutting layer is made from a polycrystalline ultra hard material, such as polycrystalline diamond (“PCD”) or polycrystalline cubic boron nitride (“PCBN”). Moreover, these cutters may employ transition layers bonded between the substrate and the cutting layer. The transition layers typically have properties which are intermediate between the properties of the substrate and the cutting layer.
To reduce the residual stresses formed on the interface between the substrate and the cutting layer and to enhance the delamination resistance of the cutting layer, irregularities are sometimes incorporated on the cutting face of the substrate, forming a non-uniform interface between the substrate and the cutting layer. When transition layers are incorporated, one or both faces of the transition layers may also be non-uniform.
As used herein, a uniform interface is one that is flat or always curves in the same direction. This can be stated differently as an interface having the first derivative of slope always having the same sign. Thus, for example, a conventional polycrystalline diamond-coated convex insert for a rock bit has a uniform interface since the center of curvature of all portions of the interface is in or through the carbide substrate.
On the other hand, a non-uniform interface is defined as one where the first derivative of slope has changing signal. An example of a non-uniform interface is one that is wavy with alternating peaks and valleys. Other non-uniform interfaces may have dimples, bumps, ridges (straight or curved) or grooves, or other patterns of raised and lowered regions in relief.
There are a few methods currently being used for forming a non-uniform interface between the substrate and the cutting layer, or between a transition layer and the substrate, or between the a transition layer and the cutting layer. One method requires presintering the substrate. Grooves or other irregularities are then milled or EDM-sunk into the cutting face of the presintered substrate. If a transition layer is to be incorporated, the transition layer may be laid in powder form over the grooved cutting face of the substrate. The ultra hard material layer is then laid over the transition layer. The ultra hard material is also typically laid in powder form.
In situations where a non-uniform interface is required between the transition layer and the ultra hard material layer grooves or other irregularities may be pressed on top of the powder transition layer during a presintering process. The ultra hard material is then applied over the presintered transition layer and the entire assembly consisting of the substrate, transition layer and ultra hard material is sintered in a conventional high temperature, high pressure process.
Other methods of forming non-uniform interfaces commonly require that the grooves are formed on the substrate cutting face during the substrate presintering process. Typically the substrate is formed from a powder tungsten carbide material. Grooves are pressed on a portion of the powder substrate that would form the cutting face while the substrate is being presintered.
As can be seen, the methods currently used for forming a cutting element having non-uniform interfaces between the cutting layer and the substrate, or between the cutting layer and a transition layer, or between the substrate and a transition layer may be labor intensive. As such, there is a need for a simpler method of forming a cutting element having a non-uniform interface.
SUMMARY OF THE INVENTION
To form a non-uniform interface between an ultra hard material cutting layer and a substrate, for example, a sheet of material which after the sintering process is the same as the substrate, is embossed on one face for forming the desired non-uniform interface. For illustrative purposes this sheet is referred to herein as the “substrate material sheet.” The substrate material sheet is cut and placed on an end of the substrate. A second sheet ultra hard material is formed and is embossed for forming a non-uniform face complementary to the embossed non-uniform face on the substrate layer. The sheet is cut and the two sheets are mated with each other over the substrate. The entire assembly consisting of the substrate, substrate material sheet and ultra hard material sheet are then sintered together, causing the substrate material sheet to become integral with the substrate and the ultra hard material sheet to bond to the resulting substrate for forming a non-uniform interface between the resulting substrate and the ultra hard material.
Similarly, a transition layer may be formed from a sheet material which after the sintering process has properties intermediate to that of the substrate and the ultra hard material layer. The transition sheet may be embossed on one face and/or both faces to form a non-uniform interface with the ultra hard material sheet, and/or the substrate material sheet, respectively. A protective coating, such as tungsten, niobium, silicon, or aluminum oxide, may be placed on top of the ultra hard material layer prior to sintering. The coating may also be in sheet form. The coating protects the polycrystalline ultra hard material layer.
Multiple ultra hard material sheets may be used to form separate polycrystalline ultra hard material layers and each sheet may be of the same type of ultra hard material, or may be a different type of ultra hard material such as diamond or cubic boron nitride, or may be of the same type of ultra hard material but have a different ultra hard material particle size. Similarly, one or multiple sheets of a transition material may be employed to form one or more transition layers. These sheets will also be embossed as necessary so that they mate with their adjacent sheets on the substrate.
REFERENCES:
patent: 4604106 (1986-08-01), Hall et al.
patent: 4610320 (1986-09-01), Beakley
patent: 4629373 (1986-12-01), Hall
patent: 4764434 (1988-08-01), Aronsson et al.
patent: 4954139 (1990-09-01), Cerutti
patent: 5011515 (1991-04-01), Frushour
patent: 5037451 (1991-08-01), Burnand et al.
patent: 5135061 (1992-08-01), Newton, Jr.
patent: 5469927 (1995-11-01), Griffin
patent: 5598750 (1997-02-01), Griffin et al.
patent: 5662720 (1997-09-01), O'Tighearnaigh
patent: 5669271 (1997-09-01), Griffin et al.
patent: 2 282 833 (1995-04-01), None
patent: 2331538 (1999-05-01), None
Eyre Ronald K.
Keshavan Madapusi K.
Bagnell David
Christie Parker & Hale LLP
Singh Sunil
Smith International Inc.
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