Tapered thread configuration with improved durability

Patent metadata

Field	Value
Publication number	US-9605491-B2
Application number	US-201514663208-A
Country	US
Kind code	B2
Filing date	Mar 19, 2015
Priority date	Dec 1, 2010
Publication date	Mar 28, 2017
Grant date	Mar 28, 2017

Abstract

Underground drilling operation often requires connecting a drill tool (e.g., drill bit, backreamer, etc.) to a drill string. It is desirable to connect the drill tools to a drill string in a manner that facilitates quick and easy assembly and disassembly. Low torque coupling, commonly referred to as “torque-less” connection, can provide such functionality. The useful life and strength of such connections can be improved upon. The present disclosure provides a low torque coupling with improved strength and durability.

First claim

We claim:

1. A threaded interface for use in connecting a removable down hole tool to a drill string, the threaded interface comprising:
a down hole end portion configured to interface with a removable down hole tool assembly;
an up hole end portion opposed to the down hole end portion, the up hole end portion being configured to interface with the drill string as part of a low torque coupling, the up hole end portion including:
a non-threaded, non-tapered first cylindrical shaped portion having a first outer diameter;
a non-threaded, non-tapered second cylindrical shaped portion having a second outer diameter that is larger than the first outer diameter;
a threaded tapered section that extends between the first cylindrical shaped portion and the second cylindrical shaped portion, the threaded tapered section including threads thereon;
an annular stress relief notch providing a transition between the threaded tapered section and one of the first and second cylindrical sections; and

a collar configured to slide over both the up hole end portion and a portion of the drill string to prevent relative rotation between the drill string and the up hole end portion.

2. The threaded interface of claim 1 , wherein the first cylindrical section, the second cylindrical section and the threaded tapered section are defined by an exterior of a male connection structure.

3. The threaded interface of claim 2 , wherein the annular stress relief notch is provided between the threaded tapered section and the second cylindrical section.

4. The threaded interface of claim 3 , wherein another annular notch is defined by the male connection structure at an intermediate location along a length of the first cylindrical section.

5. The threaded interface of claim 4 , wherein the male connection structure is a first male connection structure provided at a first end of an adapter body, wherein the adapter body has a second end defining a second male connection structure, wherein the second male connection structure defines a tapered threaded section having major and minor outer diameters that are respectively larger than corresponding major and minor outer diameters of the threaded tapered section of the first male connection structure, wherein the adapter body defines an intermediate region between the first and second male connection structures, and wherein a plurality of wrench flats are provided at the intermediate region.

6. The threaded interface of claim 5 , wherein threads on the threaded tapered section of the first male connection structure are asymmetric, some threads on the threaded tapered section of the first male connection having a width-to-height ratio of between 1.25 to 3.0.

7. The threaded interface of claim 1 , wherein the first cylindrical section, the second cylindrical section, and the threaded tapered section are defined by an interior of a female connection structure.

8. The threaded interface of claim 7 , wherein the annular stress relief notch is provided between the threaded tapered section and the first cylindrical section.

9. The threaded interface of claim 8 , wherein the female connection structure is provided at an end of a starter rod.

10. The threaded interface of claim 9 , wherein threads on the threaded tapered section are asymmetric, some threads on the threaded tapered section having a width-to-height ratio of between 1.25 to 3.0.

11. The threaded interface of claim 1 , wherein threads on the threaded tapered section are asymmetric, and wherein a distance between adjacent valleys of the threads is 1.25 to 3 times greater than the height of a thread as defined by a radial distance between a peak and a valley of a thread.

12. An adapter for connecting a down hole tool to a drill string, the adapter comprising:
a down hole end portion configured to interface with a removable down hole tool assembly;
an up hole end portion opposed to the down hole end portion, the up hole end portion being configured to interface with a drill string as part of a low torque coupling, the up hole end portion including:
a first end having a first land configured as a non-tapered cylindrical section of a first diameter;
a second end having a second land configured as a non-tapered cylindrical section of a second diameter, larger than the first diameter;
a conical portion between the first end and the second end having a threaded portion and a stress relief zone adjacent the second land; and

a collar configured to slide over both the up hole end portion and a portion of the drill string to prevent relative rotation between the drill string and the up hole end portion.

13. The adapter of claim 12 , wherein the stress relief zone includes an annular notch located between the second land and the conical portion.

14. The adapter of claim 12 , wherein threads on the conical portion are asymmetric, some threads on the conical portion having a height-to-width ratio of between 1.25 to 3.0.

15. A coupling for connecting a sonde housing to a pilot drill rod, the coupling comprising:
a down hole end portion configured to interface with the sonde housing, the down hole end including a tapered protrusion;
an up hole end portion opposed to the down hole end portion, the up hole end portion being configured to interface with the pilot drill rod as part of a low torque coupling, the up hole end portion including:
a first end portion including a threaded tapered portion positioned between a first unthreaded portion and a second unthreaded portion;
a second end portion opposite the first end portion including a tapered threaded portion;
wherein the first unthreaded portion of the first end portion has a non-tapered cylindrical shape;
wherein the second unthreaded portion of the first end portion has a non-tapered cylindrical shape and has a larger diameter than the first unthreaded portion;
wherein threads on the tapered threaded portion are asymmetric and at least some threads on the tapered threaded portion have a width-to-height ratio of between 1.25 to 3.0; and

a collar configured to slide over both the up hole end portion and a portion of the pilot drill rod to prevent relative rotation between the pilot drill rod and the up hole end portion.

16. The coupling of claim 15 , wherein variations in the diameter of the first unthreaded portion are less than 0.0015 inches and variations in the diameter of the second unthreaded portion are less than 0.0015 inches.

17. The coupling of claim 15 , wherein threads on the tapered threaded portion are configured to engage threads on a mating member such that relatively rotating the tapered threaded portion and the mating member connects the tapered threaded portion to the mating member.

18. The coupling of claim 17 , wherein threads on the tapered threaded portion are configured to engage threads on a mating member such that the pitch diameter between the threads on the tapered threaded portion and threads on the mating member is offset by at least 0.030 inches (0.76 millimeters).

19. An adapter for transferring torque, tension, thrust, and bending forces between a drill string and a drill bit that can be connected and disconnected by an operator using hand tools comprising:
a down hole end portion configured to interface with a removable down hole tool assembly;
an up hole end portion opposed to the down hole end portion, the up hole end portion being configured to interface with a drill string as part of a low torque coupling, the up hole end portion including:
a body including a first cylindrical project

Assignees

• Vermeer Mfg Co

Inventors

• Langenfeld Michael D
• Runquist Randy R

Classifications

• F16L37/146

  the securing element being a rigid pin, screw or the like · CPC title

• F16L25/08

  in the form of screws, nails or the like · CPC title

• F16L15/06

  characterised by the shape of the screw-thread · CPC title

• F16L15/001

  with conical threads · CPC title

• E21B17/03

  between drilling rod or pipe and drill motor {or surface drive}, e.g. between drilling rod and hammer · CPC title