The present invention relates generally to methods of testing super hard materials. More specifically, the present invention relates to methods of testing super hard materials used as cutters in earth drilling applications.
Super hard materials are commonly used in down-hole drilling operations that require cutters to penetrate hard and abrasive earthen formations. Polycrystalline diamond (PCD) is a super hard material commonly used in the manufacture of cutters for use in such operations. PCD cutters typically comprise diamond material formed on a supporting substrate (typically a cemented tungsten carbide (WC) substrate) and bonded to the substrate under high temperature, high pressure (HTHP) conditions.
A limiting factor to effective drilling is the wear on such cutters, so attention has been directed at designing cutters that are more wear resistant. Cutters may be subjected to abrasion tests to determine optimal cutter specifications.
One such abrasion test is disclosed in U.S. Pat. No. 5,833,021 to Mensa-Wilmot et al., which is herein incorporated by reference for all that it contains. Mensa-Wilmot discloses a test that is used to assess the life of a cutter called the granite log abrasion test which involves machining the surface of a rotating cylinder of Bane granite. To assess the cutter, one determines a wear ratio of the volume of log removed relative to the volume of cutting tool removed.
Another test is disclosed in U.S. Pat. No. 6,003,623 to Miess, which is herein incorporated by reference for all that it contains. Miess discloses a test where a cutter was used to cut Sierra white granite mounted on a vertical turret lathe to present a flat rotating surface of rock to the cutter. The cutter was mounted with a negative back rake such that its central axis formed a 5 degree angle with a line normal to the planar surface of the stone. The turret lathe was adjusted to advance the cutter radially toward the center of the stone as the stone was rotated below the cutter. The surface speed was 30 inches per second, the feed rate was 0.125 inches per revolution, and the coolant was water.
In certain embodiments of the present invention, a fixture for holding a cutter for a vertical turret lathe comprises a block. The block may comprise a blind hole within which a cutter may be secured. The cutter may comprise an indenter on a distal tip. The cutter may be secured in the hole such that a portion of the indenter is at a positive rake angle.
In another embodiment of the present invention the cutter may comprise a polycrystalline diamond material formed on a supporting substrate. The cutter may be secured within the hole with braze. The cutter may comprise a conical shape where a resultant force of all the forces acting on the cutter from the cutting material, including the sum of all vertical forces and drag forces acting on the cutter, act on the indenter of the cutter.
In another embodiment of the present invention, a method for testing cutters may comprise securing a cutter on a fixture of a vertical turret lathe which has a cutting material positioned adjacent the cutter. The cutting material may then be rotated around an axis of rotation at a constant rotational velocity. As the cutting material rotates the cutter may be pushed into the cutting material proximate the axis of rotation. The fixture may be urged laterally such that the cutter progressively moves towards a periphery of the cutting material. The rotational velocity may be decreased as the cutter moves laterally to maintain a relative constant linear velocity between the cutting material and the cutter.
In various embodiments of the invention the cutter may comprise polycrystalline diamond bonded to cemented metal carbide. The cutting material may comprise granite.
In another aspect of the invention the cutter may fail after reaching a relative constant linear velocity and before the cutter reaches the periphery of the cutting material. The failing of the cutter may occur when the cutter reaches a temperature such that the polycrystalline diamond material graphitizes.
The method for testing cutters may further comprise measuring the abrasive wear on the cutter before the relative constant linear velocity has been reached. In order to measure the wear on the cutter, the cutter may be lifted off the granite and a photograph of the cutter may be taken. The cutter wear may be quantified from the photographs taken by using optical comparators, volume displacement methods, and/or software to measure a size of a degraded edge of the material. Measuring abrasive wear may also comprise measuring a distance the cutter traveled before failing.
The method for testing cutters may further comprise rotating the cutting material at a constant rotational velocity until the cutter reaches a predetermined radial position with respect to the cutting material and then decreasing the rotational velocity as the cutter moves laterally outward to maintain a relative constant linear velocity. It may be beneficial to begin decreasing the rotational velocity before thermal expansion mismatch within the cutter becomes appreciable.
The method for testing cutters may be performed under dry conditions without lubrication.
The method for testing cutters may further comprise estimating a cutter's temperature from light emitted from the cutter during the test. Estimating the cutter temperature may be performed by comparing the emitted light to a standard. In other embodiments, a laser temperature gun or a thermal imaging camera may be used. In some embodiments a temperature probe may be incorporated into the fixture.
a is a cross-sectional diagram of an embodiment of a shear cutter engaging a cutting material at a set depth.
b is a cross-sectional diagram of an embodiment of a conical-shaped cutter engaging a cutting material at a set depth.
a is a graph of an embodiment of a linear velocity of a cutting material versus a radial position of a cutter.
b is a graph of an embodiment of a rotational velocity of a cutting material versus a radial position of a cutter.
a and 2b are cross-sectional views of embodiments of a shear cutter 200 and conical-shaped cutter 201 respectively engaging a cutting material 104 at a set depth 210. Cutters 200 and 201 may be secured in the fixture 103 with a clamp 202, with a braze 203, or with other fastening systems known in the art. The shear cutter 200 may comprise a back rake angle 205 at which the shear cutter 200 engages the cutting material 104. The conical-shaped cutter 201 may comprise an indenter 220 on its distal end. The conical shape of the conical-shaped cutter 201 may allow portions of the indenter 220 to have negative rake angles and portions of the indenter 220 to have positive rake angles. The arrow 204 in the figures indicates the relative movement of the cutting material 104. The fixture 103 may comprise a block 1102 with a blind hole 1101 therein. The cutter 201 may be secured in the blind hole 1101. The cutter 201 may comprise an indenter 220 at a distal end of the cutter 201 that may comprise a conical shape. A vertical force 1201 and a drag force 1200 may be summed to calculate a resultant force vector 1105 that may act on the indenter 220 of the cutter 201. It was shown in VTL tests that a conical-shaped cutter cut 100,000 linear feet of sierra white granite with substantially no wear on the cutter.
a and 3b are graphs of embodiments of different velocities of the cutting material 104 versus position of the cutter 102 for the present invention.
As the cutter 102 is urged to the periphery 112 of the cutting material 104 and the rotational velocity 451 is held constant 453, the linear velocity 401 seen at the cutter 102 may increase 403 at a substantially constant acceleration until it reaches a radial position 404. At this point, the rotational velocity 451 of the cutting material 104 may begin to decrease 452 in order to maintain a substantially constant 405 linear velocity 401.
The cutter temperature 600 tends to increase rapidly immediately before failure 601. It is believed that by holding the linear velocity 401 constant 405 that the rapid increase in cutter temperature 600 generally experienced during a test may be slowed such that the range of test results may be more spread out.
The step of rotating 302 the cutting material may comprise positioning the cutting material on a turntable of a vertical turret lathe. The turntable may spin at variable rotational velocity and may be controlled by a computer numerical controlled (CNC) machine. The step of pushing 303 the cutter may comprise applying a force on the cutter perpendicular to a surface of the cutting material. The cutting material may be rotating at a constant rotational velocity when the cutter first engages the cutting material. The step of urging 304 may comprise moving the cutter at a constant or variable velocity laterally across the surface of the cutting material. The step of decreasing 305 may comprise lowering the rotational velocity of the cutting material. This may be done to maintain a constant linear velocity at the cutter.
Whereas the present invention has been described in particular relation to the drawings attached hereto, it should be understood that other and further modifications apart from those shown or suggested herein, may be made within the scope and spirit of the present invention.
This application is a continuation-in-part of U.S. patent application Ser. No. 11/971,965 which is a continuation of U.S. patent application Ser. No. 11/947,644, which was a continuation-in-part of U.S. patent application Ser. No. 11/844,586. U.S. patent application Ser. No. 11/844,586 is a continuation-in-part of U.S. patent application Ser. No. 11/829,761. U.S. patent application Ser. No. 11/829,761 is a continuation-in-part of U.S. patent application Ser. No. 11/773,271. U.S. patent application Ser. No. 11/773,271 is a continuation-in-part of U.S. patent application Ser. No. 11/766,903. U.S. patent application Ser. No. 11/766,903 is a continuation of U.S. patent application Ser. No. 11/766,865. U.S. patent application Ser. No. 11/766,865 is a continuation-in-part of U.S. patent application Ser. No. 11/742,304. U.S. patent application Ser. No. 11/742,304 is a continuation of U.S. patent application Ser. No. 11/742,261. U.S. patent application Ser. No. 11/742,261 is a continuation-in-part of U.S. patent application Ser. No. 11/464,008. U.S. patent application Ser. No. 11/464,008 is a continuation-in-part of U.S. patent application Ser. No. 11/463,998. U.S. patent application Ser. No. 11/463,998 is a continuation-in-part of U.S. patent application Ser. No. 11/463,990. U.S. patent application Ser. No. 11/463,990 is a continuation-in-part of U.S. patent application Ser. No. 11/463,975. U.S. patent application Ser. No. 11/463,975 is a continuation-in-part of U.S. patent application Ser. No. 11/463,962. U.S. patent application Ser. No. 11/463,962 is a continuation-in-part of U.S. patent application Ser. No. 11/463,953. The present application is also a continuation-in-part of U.S. patent application Ser. No. 11/695,672. U.S. patent application Ser. No. 11/695,672 is a continuation-in-part of U.S. patent application Ser. No. 11/686,831. All of these applications are herein incorporated by reference for all that they contain.
Number | Date | Country | |
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Parent | 11947644 | Nov 2007 | US |
Child | 11971965 | US | |
Parent | 11766865 | Jun 2007 | US |
Child | 11766903 | US | |
Parent | 11742261 | Apr 2007 | US |
Child | 11742304 | US |
Number | Date | Country | |
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Parent | 11971965 | Jan 2008 | US |
Child | 12614614 | US | |
Parent | 11844586 | Aug 2007 | US |
Child | 11947644 | US | |
Parent | 11829761 | Jul 2007 | US |
Child | 11844586 | US | |
Parent | 11773271 | Jul 2007 | US |
Child | 11829761 | US | |
Parent | 11766903 | Jun 2007 | US |
Child | 11773271 | US | |
Parent | 11742304 | Apr 2007 | US |
Child | 11766865 | US | |
Parent | 11464008 | Aug 2006 | US |
Child | 11742261 | US | |
Parent | 11463998 | Aug 2006 | US |
Child | 11464008 | US | |
Parent | 11463990 | Aug 2006 | US |
Child | 11463998 | US | |
Parent | 11463975 | Aug 2006 | US |
Child | 11463990 | US | |
Parent | 11463962 | Aug 2006 | US |
Child | 11463975 | US | |
Parent | 11463953 | Aug 2006 | US |
Child | 11463962 | US | |
Parent | 11695672 | Apr 2007 | US |
Child | 11463953 | US | |
Parent | 11686831 | Mar 2007 | US |
Child | 11695672 | US |