US20080041632A1

US20080041632A1 - Earth bit having a retaining ring

Info

Publication number: US20080041632A1
Application number: US11/840,524
Authority: US
Inventors: Gregory W. Peterson
Original assignee: Atlas Copco Secoroc LLC
Current assignee: Epiroc Drilling Tools LLC
Priority date: 2006-08-18
Filing date: 2007-08-17
Publication date: 2008-02-21

Abstract

An earth bit includes an earth bit body which carries a lug. The lug is repeatably attachable to and detachable from the earth bit body. A retaining ring retains the lug to the earth bit body and restricts the movement of the lug in response to a force applied to it. The retaining ring has a height less than its diameter.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application claims priority to U.S. Provisional Application No. 60/822,894 filed in Aug. 18, 2006, the contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention
This invention relates generally to earthboring tools for boring a hole.
2. Description of the Related Art
Earthboring tools are commonly used to bore holes by cutting through earthen annulus. Such holes may be bored for many different reasons, such as drilling for oil, minerals and water. One type of earthboring tool used for boring is a rotary earth bit. Several examples of rotary earth bits are disclosed in U.S. Pat. Nos. 3,550,972, 3,847,235, 4,136,748, 4,427,307, 4,688,651 and 4,741,471. A rotary earth bit generally includes one or more lugs which form an earth bit body. A cutting cone is rotatably mounted to each lug with a journal bearing, which includes ball and roller bearings. The cutting cone is engaged with the ball and roller bearings and rotates about the journal bearing as the lug rotates.
It is known that earthboring tools wear down with use. For example, the portion of the earth bit proximate to the lugs experience a significant amount of wear. However, the earth bit can fail and will need to be replaced if it wears down enough. Replacing an earth bit is costly and time consuming, so it is desirable to decrease the amount of wear the earth bit experiences.

BRIEF SUMMARY OF THE INVENTION

The present invention employs an earth bit which includes an earth bit body and a lug, with the lug being repeatably attachable to and detachable from the earth bit body. A retaining ring retains the lug to the earth bit body and restricts the movement of the lug in response to a force applied to it. The retaining ring can be frictionally or threadingly engaged with the lug and earth bit body. The retaining ring can also be engaged with the lug and earth bit body by using welding or an interference fit. The retaining ring is positioned so the portion of the earth bit proximate to the lug experiences less wear.
Further features and advantages of the invention will be apparent to those skilled in the art from the following detailed description, taken together with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an earth bit having a retaining ring, in accordance with the invention.

FIG. 2 is a close-up side view of the earth bit of FIG. 1 showing the retaining ring.

FIGS. 3 a and 3 b are top views showing a lug and retaining ring disengaged from and engaged to, respectively, an earth bit body of the earth bit of FIG. 1.

FIGS. 4 a and 4 b are perspective and plan views, respectively, of the retaining ring of FIG. 1.

FIGS. 5 and 6 are flow diagrams of methods of assembling and disassembling, respectively, an earth bit, in accordance with the invention.

FIG. 7 is a flow diagram of a method of modifying an earth bit, in accordance with the invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a perspective view of an earth bit 100, in accordance with the invention. In this embodiment, earth bit 100 includes an earth bit body 101 which carries three lugs 102 coupled to corresponding cutting cones 103. In this way, earth bit 100 is a tri-cone earth bit. It should be noted that lugs 102 and earth bit body 101 can be a single integrated piece, but here they are separate pieces so that lugs 102 are attachable to and detachable from earth bit body 101 in a repeatable manner. In operation, as earth bit body 101 rotates, lugs 102 rotate, and cutting cones 103 rotate in response to contacting earthen annulus.
In accordance with the invention, earth bit 100 includes a retaining ring 105 positioned to retain lugs 102 to earth bit body 101 and to restrict the movement of lugs 102 in response to a force applied to them. In this embodiment, lug 102 is also retained to earth bit body 101 with weldments 118. The force applied to lugs 102 is often provided in response to them or cutting cones 103 contacting earthen annulus. As will be discussed in more detail presently, retaining ring 105 is also positioned so the portion of earth bit 100 proximate to lugs 102 experience less wear.
FIG. 2 is a close-up side view of earth bit 100 showing retaining ring 105 around a region 104 of FIG. 1. In this embodiment, retaining ring 105 retains lug 102 to earth bit body 101. Further, lug 102 is fastened to earth bit body 101 with fasteners 106 and 107. In this view, the portion of lug 102 that is covered by retaining ring 105 is shown in phantom with dotted lines. Fasteners 106 and 107 are also shown in phantom with dotted lines because they are also covered by retaining ring 105. Fasteners 106 and 107 can be of many different types, such as bolts. Fasteners 106 and 107 are repeatably moveable between positions attaching and unattaching lug 102 to earth bit body 101. In this way, lugs 102 are attachable to and detachable from earth bit body 101 in a repeatable manner.
In this embodiment, lug 102 is attached to earth bit body 101 so there is an interface 109 therebetween. Portions of interface 109 can be covered by weldments (not shown) that extend between earth bit body 101 and lug 102. For example, weldments can be positioned so they extend through regions 110, 111 and/or 112. Regions 110, 111 and 112 extend between earth bit body 101 and lug 102 and across interface 109. Hence, the weldments extend through interface 109 and provide a force which holds earth bit body 101 and lug 102 together. Regions 110, 111 and 112 are shown in phantom with dotted lines because, in this embodiment, they are covered by retaining ring 105. Hence, retaining ring 105 covers interface 109.
Without retaining ring 105, portions of earth bit 100 proximate to interface 109 can undesirably wear down when contacting earthen annulus and can cause earth bit 100 to fail. When earth bit 100 fails, it needs to be replaced, which is costly and time consuming. One situation where earth bit 100 fails is when lug 102 undesirably detaches from earth bit body 101. Lug 102 can undesirably detach from earth bit body 101 in many different ways, such as when the weldments that extend through regions 110, 111 and/or 112 break. Another way lug 102 can undesirably detach from earth bit body 101 is when fasteners 106 and 107 break. The weldments and fasteners 106 and 107 break when they no longer hold earth bit body 101 and lug 102 together. Hence, it is desirable to decrease the amount of wear earth bit 100 experiences. It should be noted that the weldments and fasteners 106 and 107 can break in many different ways, such as in response to contacting earthen annulus.
In accordance with the invention, retaining ring 105 is positioned to cover the weldments that extend through regions 110, 111 and 112, as well as fasteners 106 and 107, so that their contact with earthen annulus is restricted. In this way, the weldments and fasteners experience less wear and are less likely to break. Hence, lug 102 is less likely to detach from earth bit body 101 and earth bit 100 is less likely to fail. Since earth bit 100 is less likely to fail, it needs to be replaced less often, so it is less costly to operate.
FIGS. 3 a and 3 b are top views showing lug 102 and retaining ring 105 disengaged from and engaged to, respectively, earth bit body 101. It should be noted that retaining ring 105, lug 102 and earth bit body 101 are generally curved, but here they are shown as being straight for simplicity. In this embodiment, earth bit body 101 includes a channel 108 (FIG. 3 a) which is sized and shaped to receive lug 102, as shown in FIG. 3 b. Retaining ring 105 is positioned to engage earth bit body 101 and lug 102 so that lug 102 is retained in channel 108, as shown in FIG. 3 b.
Retaining ring 105 engages lug 102 and earth bit body 101 at interfaces 113 and 114, respectively. It should be noted that the surfaces of retaining ring 105 and lug 102 that form interface 113 can be threadingly or frictionally engaged together. The surfaces of retaining ring 105 and lug 102 that form interface 113 can also be engaged together by using welding or an interference fit. Further, the surfaces of retaining ring 105 and earth bit body 101 that form interface 114 can be threadingly or frictionally engaged together. When surfaces are threadingly engaged, one includes threads and the other includes complementary threads. When surfaces are frictionally engaged together, they include a surface roughness which provides friction between them. In this way, retaining ring 105 can be frictionally or threadingly engaged with earth bit body 101 and/or lugs 102. In other embodiments, welding or an interference fit can be used.
FIGS. 4 a and 4 b are perspective and top views of retaining ring 105. In this embodiment, retaining ring 105 is annular in shape so it has a central opening 119 extending therethrough, wherein central opening 119 is bounded by an inner surface 115. Central opening 119 is sized and dimensioned to receive earth bit body 101 and lugs 102 when they are engaged together, as shown in FIG. 3 b. Earth bit body 101 and lugs 102 generally engage inner surface 115 when received by central opening 119.
Retaining ring 105 has a diameter d, which can correspond to many different diameters of ring 105. For example, diameter d can correspond to an inner diameter d₁or an outer diameter d₂, as shown in FIG. 4 b. Diameter d can also correspond to a diameter intermediate to diameters d₁and d₂. In this embodiment, retaining ring 105 has a height h that is less than its diameter d.
It should be noted that inner surface 115 can engage lug 102 and earth bit body 101 in many different ways. For example, in the embodiments wherein retaining ring 105 is frictionally engaged with lug 102 and/or earth bit body 101, inner surface 115 has a roughness to provide a desired amount of friction between it and lug 102 and earth bit body 101. In the embodiments wherein retaining ring 105 is threadingly engaged with lug 102 and/or earth bit body 101, inner surface 115 includes threads 117, as indicated by a substitution arrow 116. Threads 117 engage corresponding threads on lug 102 and/or earth bit body 101, as described above.
FIG. 5 is a flow diagram of a method 120 of assembling an earth bit, in accordance with the invention. In this embodiment, method 120 includes a step 121 of providing an earth bit body and a step 122 of providing a lug. The earth bit can be of many different types, such as a tri-cone earth bit, which includes three lugs and corresponding cutting cones.
In accordance with the invention, method 120 includes a step 123 of positioning a retaining ring so it retains the lug to the earth bit body. The retaining ring can be positioned in many different ways, but it is generally positioned so it covers the interface between the lugs and earth bit body. In this way, the region of the earth bit proximate to the lug and earth bit body will experience less wear when the earth bit is used to bore through earthen annulus.
It should be noted that the retaining ring can be threadingly or frictionally engaged with the lug and/or earth bit body. However, welding or an interference fit can also be used. Further, the retaining ring can have many different shapes and dimensions. In this embodiment, the retaining ring is annular in shape and has a diameter that is greater than its height. The diameter of the retaining ring can be its inner or outer diameter, or a diameter value in between.
It should also be noted that method 120 can include many other steps. For example, method 120 can include a step of fastening the lug to the earth bit body with a fastener. The lug can be fastened to the earth bit body in many different ways, such as by using one or more bolts. The lug can also be fastened to the earth bit body by using one or more weldments. In some embodiments, the retaining ring is positioned to cover the fasteners and at least some of the weldments. In this way, the fasteners and weldments experience less wear when the earth bit is used to bore through earthen annulus.
FIG. 6 is a flow diagram of a method 125 of disassembling an earth bit, in accordance with the invention. In this embodiment, method 125 includes a step 126 of providing an earth bit which includes a lug retained to an earth bit body with a retaining ring. Method 125 includes a step 127 of removing the retaining ring from the lug and earth bit body. The retaining ring can be removed from the lug and earth bit body in many different way. For example, the retaining ring can be threadingly or frictionally disengaged therefrom. In other embodiments, retaining ring can be disengaged from lug by breaking a weldment or by overcoming an interference fit.
In some embodiments, method 125 includes a step 128 of removing the lug from the earth bit body. The lug can be removed from the earth bit body in many different ways. For example, fasteners that hold the lug to the earth bit body can be unfastened to allow the lug to be moved away from the earth bit body. In some examples, the lug is fastened to the earth bit body with one or more weldments. In these examples, the removal of the lug from the earth bit body involves breaking the weldment so that the lug is allowed to be moved away from the earth bit body.
FIG. 7 is a method 130 of modifying an earth bit, in accordance with the invention. In this embodiment, method 130 includes a step 131 of providing an earth bit which includes an earth bit body and a lug. The lug and earth bit body are typically fastened together. The lug and earth bit body can be fastened together in many different ways, such as with a fastener and/or weldment. Method 130 includes a step 132 of positioning a retaining ring so it retains the lug to the earth bit body. The retaining ring is generally positioned so it covers the interface between the lug and earth bit body. If desired, the retaining ring is also positioned so it covers the fastener and weldment. In this way, the fastener, weldment and interface between the lug and earth bit body experience less wear when the earth bit is used to bore through earthen annulus.
While particular embodiments of the invention have been shown and described, numerous variations and alternate embodiments will occur to those skilled in the art. Accordingly, it is intended that the invention be limited only in terms of the appended claims.

Claims

1. An earth bit, comprising:

an earth bit body;

a lug; and

a retaining ring which retains the lug to the earth bit body, wherein the retaining ring has a height that is less than its diameter.

2. The earth bit of claim 1, wherein the lug is repeatably attachable to and detachable from the earth bit body.

3. The earth bit of claim 1, wherein the lug is fastened to the earth bit body with a fastener.

4. The earth bit of claim 3, wherein the retaining ring covers the fastener.

5. The earth bit of claim 1, further including a plurality of lugs retained to the earth bit body by the retaining ring.

6. The earth bit of claim 1, further including a weldment which welds the lug and earth bit body together.

7. An earth bit, comprising:

an earth bit body;

a lug carried by the earth bit body; and

a retaining ring which restricts the movement of the lug in response to a force applied to it.

8. The earth bit of claim 7, wherein the retaining ring has a diameter that is greater than its height.

9. The earth bit of claim 7, wherein the retaining ring is repeatably moveable between positions engaging and disengaging the lug and earth bit body.

10. The earth bit of claim 7, wherein the lug is fastened to the earth bit body with a fastener and/or weldment.

11. The earth bit of claim 10, wherein the retaining ring covers the fastener and/or weldment.

12. The earth bit of claim 7, wherein the retaining ring is frictionally engaged with the lug and earth bit body.

13. The earth bit of claim 7, wherein the retaining ring is threadingly engaged with the lug and/or earth bit body.

14. The earth bit of claim 7, further including a cutting cone coupled to the lug, the retaining ring being positioned to restrict the movement of the lug in response to a force applied to the cutting cone.

15. A tri-cone earth bit, comprising:

an earth bit body;

a lug carried by the earth bit body, the lug being repeatably attachable to and detachable from the earth bit body; and

a retaining ring threadingly engaged with the earth bit body.

16. The earth bit of claim 15, wherein the retaining ring has a height less than its diameter.

17. The earth bit of claim 15, wherein the retaining ring restricts the movement of the lug in response to a force applied to it.

18. The earth bit of claim 15, wherein the retaining ring is threadingly engaged with the lug.

19. The earth bit of claim 15, wherein the retaining ring covers an interface between the lug and earth bit body.

20. The earth bit of claim 19, further including a weldment which extends through the interface.