Test Fixture that Positions a Cutting Element at a Positive Rake Angle

• US 20100054875A1
• Filed: 11/09/2009
• Published: 03/04/2010
• Est. Priority Date: 08/11/2006
• Status: Active Grant

• Current Assignee: Schlumberger Technology Corporation (SLB)
• Original Assignee: Schlumberger Technology Corporation (SLB)
• Inventors: Morris, Thomas, Hall, David R.
• Granted Patent: US 8,453,497 B2
• Time in Patent Office: Days
• US Class Current: 407/100
• CPC Class Codes: B23B 2226/315 polycrystalline [PCD]
• CPC Class Codes: B23B 2226/75 Stone, rock or concrete
• CPC Class Codes: B23B 2240/08 Brazed connections
• CPC Class Codes: B23B 27/1666 with plate-like cutting inserts clamped by a clamping member acting almost perpendicularly on chip-forming plane B23B27/1677 takes precedence
• CPC Class Codes: B23B 27/18 with cutting bits or tips or cutting inserts rigidly mounted, e.g. by brazing
• CPC Class Codes: B28D 1/188 with exchangeable cutter bits or cutter segments
• CPC Class Codes: G01N 3/56 Investigating resistance to wear or abrasion
• CPC Class Codes: G01N 3/58 Investigating machinability by cutting tools; Investigating the cutting ability of tools
• CPC Class Codes: Y10T 407/2268 with chip breaker, guide or deflector
• CPC Class Codes: Y10T 407/26 comprising cutting edge bonded to tool shank
• CPC Class Codes: Y10T 407/27 comprising tool of specific chemical composition

Abstract

A fixture for holding a cutter for a vertical turret lathe may comprise a block with a blind hole. A cutter with an indenter on its distal end may be secured within the hole such that a portion of the indenter comprises a positive rake angle.

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 be rotated around a rotational axis at a constant rotational velocity. 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.

Claims

1. A fixture for holding a cutter for a vertical turret lathe, comprising:

a block comprising a hole;

a cutter secured within the hole and comprising an indenter on a distal tip; and

wherein the cutter is secured within the hole such that a portion of the indenter comprises a positive rake angle.

2. The fixture of claim 1, wherein the cutter comprises a polycrystalline diamond material formed on a supporting substrate.

3. The fixture of claim 2, wherein the cutter is secured within the hole with braze.

4. The fixture of claim 1, wherein the cutter comprises a conical shape.

5. The fixture of claim 1, wherein a resultant force is acting on the indenter of the cutter.

6. The fixture of claim 5, wherein the resultant force comprises a sum of a vertical force and a drag force acting on the cutter.

7. A method for testing cutters, comprising the steps of:

securing a cutter on a fixture of a vertical turret lathe, the lathe comprising a cutting material positioned adjacent the cutter;

rotating the cutting material around an axis of rotation at a constant rotational velocity;

pushing the cutter into the cutting material proximate the axis of rotation as the cutting material rotates;

urging the fixture laterally such that the cutter progressively moves towards a periphery of the cutting material; and

decreasing the rotational velocity as the cutter moves laterally to maintain a relative constant linear velocity between the cutting material and the cutter.

8. The method of claim 7, wherein the cutter comprises polycrystalline diamond bonded to cemented metal carbide.

9. The method of claim 7, wherein the cutting material comprises granite.

10. The method of claim 7, further comprising failing the cutter after reaching the relative constant linear velocity and before the cutter reaches the periphery of the cutting material.

11. The method of claim 10, wherein failing the cutter comprises reaching a temperature between a polycrystalline diamond material on the cutter and the cutting material such that the polycrystalline diamond material graphitizes.

12. The method of claim 7, further comprising measuring abrasive wear of the cutter before the relative constant linear velocity has been reached.

13. The method of claim 12, wherein the measuring abrasive wear of the cutter comprises lifting the cutter off the cutting material at least once and taking at least one photograph of the cutter.

14. The method of claim 13, wherein the measuring abrasive wear of the cutter further comprises using optical comparator, volume displacement methods, and/or software to measure a size of a degraded edge of the cutter.

15. The method of claim 12, further comprising measuring thermal stability by measuring a distance the cutter traveled before it fails.

16. The method of claim 7, wherein the rotating the cutting material at a constant rotational velocity occurs before the cutter reaches a predetermined radial position with respect to the cutting material and wherein the decreasing the rotational velocity occurs after the cutter reaches the predetermined radial position.

17. The method of claim 7, wherein the rotating the cutting material at a constant rotational velocity occurs before thermal expansion mismatch within the cutter becomes appreciable.

18. The method of claim 7, wherein pushing the cutter into the cutting material is performed under dry conditions.

19. The method of claim 7, further comprising estimating a cutter temperature from a light emitted from the cutter.

20. The method of claim 19, wherein the estimating the cutter temperature comprises comparing the light emitted from the cutter to a standard.