DRILL STRING APPARATUS

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of and priority to U.S. Provisional Patent Application Ser. No. 63/729,028 filed on 6 Dec. 2024 and entitled “DRILL STRING APPARATUS,” which application is expressly incorporated herein by reference in its entirety.

BACKGROUND

Significant advances in drilling technology have been made, including down-the-hole (DTH) drilling. In DTH systems, the energy source (i.e., a pressurized fluid) is constantly behind the drill bit. A drill string attached to the drill bit may be rigid, having a diameter only slightly less than that of the drill bit. Large amounts of fluid can be passed through the drill string to operate the DTH Hammer, which is then used to efficiently flush the borehole clean.

DTH drilling provided several benefits. Due to their relatively light weight and ease of operation, DTH drilling has enabled more accurate positioning of the drill hole. Additionally, drill holes could be drilled to increasing depths without the loss of performance because the energy source was always directly behind the drill bit. While many systems were limited in the hardness of the rock through which they could drill, DTH systems may drill in almost all rock conditions. This has led to increased safety and penetration rates, reducing the cost per meter drilled, particularly in drill holes having small hole diameters. While initially used within the blast hole industry, DTH systems have been used in other applications, such as water well drilling, reverse circulation drilling, horizontal directional drilling, and construction work. Despite these advancements, there is a need for additional improvements to DTH drilling apparatus, specifically its ability to be steered and controlled in the downhole environment.

The subject matter claimed herein is not limited to embodiments that solve any disadvantages or that operate only in environments such as those described above. Rather, this background is only provided to illustrate one exemplary technology area where some embodiments described herein may be practiced.

BRIEF SUMMARY

Disclosed are drill-string apparatus comprising a physical coupling between a down-the-hole (DTH) hammer and a drill bit. The DTH hammer may be configured to translate axial thrust to rotational movement to unidirectionally rotate the drill bit relative to the housing. The DTH hammer may comprise a first helical spline physically coupled to the drill bit, and a second helical spline coupled to the first helical spline and physically connected to a drill string. The drill-string apparatus may be configured such that a reciprocating displacement of the DTH hammer causes rotational displacement of the drill bit via movement of the first helical spline along the second helical spline.

The unidirectional bearing may translate axial thrust of the DTH hammer into a rotational movement. The drill-sting apparatus may further comprise a first unidirectional bearing attached to a drive of the DTH hammer, wherein the first unidirectional bearing is coupled to the first helical spline. A second unidirectional bearing may be attached to a housing of the DTH hammer.

The drill-string apparatus may be configured such that when the DTH hammer reciprocates toward the drill bit, the first helical spline is pushed forward and twists along the second helical spline in a first direction, the first direction comprising a free-wheel direction of the first unidirectional bearing and an engaged direction of the second unidirectional bearing. The drill-string apparatus may also be configured such that after the DTH hammer reciprocates toward the drill bit, a weight of the drill string on the drill bit causes the DTH hammer to push backward and twist along the second helical spline in a second direction, the second direction comprising an engaged direction of the first unidirectional bearing and a free-wheel direction of the second unidirectional bearing. Thus, the second unidirectional bearing may be configured to only allow for indexing motion in the second direction while preventing rotation of the drill bit in the first direction.

The unidirectional bearing may comprise a sprag bearing, roller ramp bearing, or other unidirectional bearing. The DTH hammer may comprise a hydraulic or a pneumatic hammer. The drill-string apparatus may be configured to use energy from a retraction stroke of the DTH hammer to cause the rotational displacement of the drill bit. A compression spring may be positioned to exert a force along the first helical spline. The drill-string apparatus may further comprise a steering mechanism.

The indexed-motion apparatus may be employed in other reciprocating equipment such as a jackhammer, construction equipment or any other reciprocating equipment that has a fixed body and extending and retracting working end. The indexed-rotation apparatus may comprise a physical coupling between a control body and a reciprocating moving end, a first unidirectional bearing attached to the control body, wherein the first unidirectional bearing is coupled to the moving end, and a second unidirectional bearing oriented in a opposite direction and coupled between the control body and reciprocating end. The indexed-rotation apparatus may be configured such that when the equipment reciprocates forward, the first unidirectional bearing turns in a free-wheel direction, and the second unidirectional bearing turns in an engaged direction.

The first and second unidirectional bearings may translate axial thrust of the hammer into a rotational movement. The indexed-rotation apparatus may be configured such that when the hammer reciprocates toward the bit, the first unidirectional bearing turns in an engaged direction, and the second unidirectional bearing turns in a free-wheel direction. The second unidirectional bearing may be configured to only allow for indexing motion in a second direction while preventing rotation of the bit in a first direction. The indexed-rotation apparatus may be configured to use energy from a retraction stroke of the hammer to cause a rotational displacement of the bit. The hammer may comprise a percussive top hammer.

A method for operating an indexing down-the-hole hammer (IDTH) comprising activating the IDTH hammer to propel a drive body forward, causing a first helical spline to travel along a second helical spline in a direction of free rotation of a first unidirectional bearing that is coupled to the first helical spline, wherein the first unidirectional bearing is attached to a drive of the IDTH hammer, causing a weight on a drill bit to force the drive of the IDTH hammer to retract; and during the retract motion, causing the first helical spline to travel along the second helical spline in a direction of engaged rotation of the first unidirectional bearing, the engaged first unidirectional bearing causing an indexed rotational displacement of the drill bit which is then maintained by the second unidirectional bearing.

Also disclosed is a method for operating a drill string apparatus comprising providing a drill string apparatus, wherein the drill string apparatus comprises a drill string and an indexing down-the-hole (IDTH) hammer, and activating the IDTH Hammer to drill forward by causing at least a portion of the IDTH hammer to rotate, wherein during activating of the IDTH Hammer the drill string does not rotate or rock. The drill string may comprise a bent housing and the direction of the bent housing may be maintained such that the bent housing is not rotated. A bore formed by the drill string apparatus may comprise vertical bore or horizontal directional bore drilling. Activating the IDTH Hammer may comprise forward circulation or reverse circulation boring.

The method may comprise directionally steering a rotary borehole. Steering may be accomplished without rocking the drill bit and/or without employing a carve steering technique. Specifically, the method may enable horizontal directional drilling using traditional directional drilling techniques. The method may further comprise use of a surveying instrument, or a rod communication system to facilitate location of the drill bit to an operator.

This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

Additional features and advantages will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by the practice of the teachings herein. Features and advantages of the invention may be realized and obtained by means of the instruments and combinations particularly pointed out in the appended claims. Features of the present invention will become more fully apparent from the following description and appended claims or may be learned by the practice of the invention as set forth hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to describe the manner in which the above-recited and other advantages and features can be obtained, a more particular description of the subject matter briefly described above will be rendered by reference to specific embodiments which are illustrated in the appended drawings. Understanding that these drawings depict only typical embodiments and are not therefore to be considered to be limiting in scope, embodiments will be described and explained with additional specificity and detail through the use of the accompanying drawings in which:

FIGS. 1A through 1C illustrate a down-the-hole hammer drill.

FIG. 2 illustrates an embodiment of a drill-string apparatus.

FIG. 3 illustrates a cross-sectional view of the drill-string apparatus of FIG. 2.

FIGS. 4A and 4B illustrate a front view of the first and second unidirectional bearings, respectively.

FIG. 5 illustrates a cross-sectional perspective view of the drive body.

FIG. 6 illustrates a cross-sectional perspective view of the housing of the drill-string apparatus of FIG. 2.

FIG. 7 illustrates the interface between the spiral gear of the drive body and the mating gear of the housing.

FIGS. 8A and 8B illustrate the interaction between the hammer of the drill string with the mallet of the drive body.

FIGS. 9 through 11 illustrate a cross-sectional view of the drill-string apparatus during actuation.

FIG. 12 illustrates a loader comprising a jack hammer employing the drill-string apparatus of FIG. 2.

DETAILED DESCRIPTION

The following discussion now refers to drilling-string apparatus and a number of methods and method acts that may be performed. It will be noted that, as used in this specification and the appended claims, the singular forms “a,” “an” and “the” do not exclude plural referents unless the context clearly dictates otherwise. Thus, for example, an embodiment referencing a singular referent (e.g., “widget”) may also include two or more such referents.

The embodiments disclosed herein should be understood as comprising/including disclosed components and may therefore include additional components not specifically described. Optionally, the embodiments disclosed herein are essentially free or completely free of components that are not specifically described. That is, non-disclosed components may optionally be completely omitted or essentially omitted from the disclosed embodiments.

It will also be appreciated that embodiments described herein may also include properties and/or features (e.g., ingredients, components, members, elements, parts, and/or portions) described in one or more separate embodiments and are not necessarily limited strictly to the features expressly described for that particular embodiment. Accordingly, the various features of a given embodiment can be combined with and/or incorporated into other embodiments of the present disclosure. Thus, disclosure of certain features relative to a specific embodiment of the present disclosure should not be construed as limiting application or inclusion of said features to the specific embodiment. Rather, it will be appreciated that other embodiments can also include such features.

Although the method acts may be discussed in a certain order or illustrated in a flow chart as occurring in a particular order, no particular ordering is required unless specifically stated or required because an act is dependent on another act being completed prior to the act being performed.

Definitions

The terms “proximal” and “distal” are meant to refer to portions of the DTH hammer and/or drill string or to relative directions along the hammer and/or drill string. The term “distal” may refer to positions along the device lying closer to the drill bit, i.e., the end of the drill string excavating below ground, whereas the term “proximal” may refer to positions closer to the portion of the drill string lying above ground and/or closer to an operator of the drill string.

The term “virgin rock” is meant to refer to fresh, uncracked rock that has not been previously disturbed by drilling operations.

The terms “indexing” and “indexing motion” are meant to refer to precise rotational movement of the drive body of the hammer relative to the housing.

Introduction

Down-the-Hole drilling is the industry standard for drilling through hard rock. DTH drilling works by using compressed air or other fluid to push or strike the drill bit to strike and crack the underlying rock. In DTH drilling, the percussion mechanism - commonly called the hammer - is located directly above the drill bit. The pipes of the drill string transmit the necessary feed force and rotation to the hammer and the bit, along with the fluid used to actuate the hammer and flush the cuttings. The pipes may then be added to the drill string successively behind the hammer as the hole gets deeper.

FIGS. 1A through 1C illustrate a drill string 100. A drill string 100 may comprise drill tubing physically coupled to a drill bit 110. Importantly, the drill bit 110 may be rotated for striking and/or cracking virgin rock. Rotating the drill bit 110 ensures that the entire rock surface in front of the drill bit 110 is struck, cracking the rock evenly and increasing drilling rates.

FIGS. 1B and 1C illustrate that conventional drill string 100 may comprise a bend 105 in the drill string 100 to enable steering of the drill bit 110 in the desired direction. To steer, the drill string 100 may be rotated (e.g., in direction D1) to position the bend 105 and orient the drill bit 110 in the desired drilling direction. However, later rotation of the drill string 100 to rotate the drill bit 110 for cracking virgin rock may change the position of the bend 105 as well as the drilling direction of the drill bit 110. The rotation of the bend 105 can continually change the direction of the bore, which may prevent an operator from accurately steering the bore.

FIGS. 1B and 1C illustrate the distal end of a DTH drill string 100. The drill string 100 may comprise a bend 105 that may be used to steer the drill bit 110 in a desired direction. Additionally, the bend 105 in the drill string 100 may prevent effective rotation of the drill string 110, with the radius of the bend 105 being greater than the radius of the drill string 100. As shown in FIG. 1C, the drill string 100 may be rotated continuously so as to widen the drilling hole and to provide room for correct positioning of the bend 105 and the drill bit in the desired drilling direction. In some embodiments, this is not a desirable outcome. Instead, the drilling hole walls should not be “carved out” by the bend 105.

Other conventional drill string 100 may employ angled-face drill bits 110 rather than a bend in the drill string 100 to effectuate steering. The angled-face drill bit 110 may comprise a distal surface contact with virgin rock and an angled surface extending at an oblique angle from the distal surface. The drill string 100 may attach to and rotate the angled-face drill bit 110. The angled surface may push against the rock to force the drill bit 110 away from the rock. By rocking clockwise and counter-clockwise the angled-face drill bit 110 an operator may effectively steer the drill string 100.

To maintain the steering direction of the drill bit 110, an operator may rotate the drill bit 110 back and forth in clockwise and counterclockwise directions. For example, the operator may rotate the drill bit 110 between a positive 15 degrees rotation and a negative 15 degrees rotation relative to the desired direction of the drill bit 110 to steer the drill string 100 and simultaneously evenly strike virgin rock.

However, rotating the drill string 100 in multiple directions (e.g., both clockwise and counterclockwise directions) may be detrimental to the drilling process. Typically, the tubes of the drill string 100 will be coupled together via a threaded connection, with the drill bit 110 similarly coupled to the drill string 100 via a threaded connection. Thus, rotation in a first direction in the direction of the threads may tighten or maintain the connection, but rotation in a second direction opposite the first direction may loosen or decouple the connections of the drill string 100. Additionally, because of the flex in the drill string 100 (e.g., due to the deflection of the tubing length), greater rotation at the far proximal end may be needed in order for a minimal rotation of the drill bit 110. This may increase the likelihood that the drill bit 110 is decoupled from the drill string 100 and that the location of the bend becomes unknown based on the position of the proximal end of the drill string.

The embodiments of the hammer described below enable rotation of the drill bit 110 independent of rotation of the drill string 100. In this manner, the drilling/steering direction of the drill bit 110 may be maintained while continuing to rotate the drill bit 110 so as to improve and/or maintain the drilling rate, increase depth capacity since steering is no longer dependent on the drill string rotation, and increased steering accuracy of the bore. The hammer also enables the drill bit 110 to be rotated in a manner such that there is reduced risk of decoupling the drill bit 110 from the drill string 100.

Down-The-Hole (DTH) Hammer Configuration

FIGS. 2 and 3 illustrate the drill-string apparatus 200, with FIG. 2 illustrating a perspective view and FIG. 3 illustrating a cross-sectional view of the drill-string apparatus 200. The drill-string apparatus 200 may comprise a drive body 240 (see FIG. 5) having a longitudinal axis LA and at least partially disposed within a housing 210. The housing 210 may be connected to the drill string 100. For example, the proximal end 212 of the housing 210 may comprise a threaded connection for forming a connection with the drill string 100. In this manner, the housing 210 may be rotationally secured to the drill string 100, such that the housing 210 may not rotate relative to the drill string 100.

The drive body 240 may include a mallet 230, a bit box 250, and a hammer drive 260 coupled to the bit box 250. The mallet 230 may be configured to receive a strike from a hammer of the drill string 100 and to transmit the force of the strike to the rest of the drive body 240. The mallet 230 may be connected to the hammer drive 260 and the hammer drive 260 may be connected to the bit box 250. The mallet 230, bit box 250, and hammer drive 260 may be connected such that a rotation of one of the above components may be transmitted into rotation of another component. Thus, rotation of the hammer drive 260 may be transmitted into rotation of the bit box 250 and/or the mallet 230.

The connection of the hammer drive 260 with the bit box 250 and/or the mallet may comprise a threaded connection. For example, the proximal end 262 of the hammer drive 260 may be threaded into the distal end of the mallet 230 and/or a distal end 264 of the hammer drive 260 may be threaded into the proximal end 252 of the bit box 250. The above threaded connections may be in the same direction as the rotational direction of the drive body 240, such that rotation of the drive body 240 serves to tighten and/or maintain the connection of the hammer drive 260 with the bit box 250 and/or mallet 230. In other embodiments, the hammer drive 260 may form a unitary construction with the bit box 250 and/or the mallet 230.

The mallet 230 may be disposed at least partially within the housing 210 and may extend from the proximal end 212 of the housing 210. So configured, a strike from the hammer of the drill string 100 may cause the mallet 230 (and remaining portions of the drive body 240) to translate distally, the mallet 230 being driven into the interior of the housing 210.

The drive body 240 may also comprise a spiral gear 270 having a first helical spline 272 disposed about the hammer drive 260, and first unidirectional bearings 280 disposed between the hammer drive 260 and the spiral gear 270. The spiral gear 270 may be configured to rotate about the hammer drive 260. In particular, cooperation between the spiral gear 270, the first unidirectional bearing 280, and the hammer drive 260 may allow the spiral gear 270 to be rotated about the hammer drive 260 in only a single direction (i.e., in a first direction or free-wheel direction of the first unidirectional bearing 280) while preventing rotation of the spiral gear 270 in an engaged direction relative to the hammer drive 260.

The bit box 250 may include an open distal end 254 and may be configured (e.g., with threading) to receive a drill bit according to the needs of the operator of the drill string 100, such that there is a physical coupling between the drill-string apparatus 200 and the drill bit. One or more second unidirectional bearings 290 may be disposed between the bit box 250 and the housing 210 so as to control the rotation of the bit box 250 relative to the housing 210. In a manner similar to the spiral gear 270, first unidirectional bearing 280, and hammer drive 260 above, the second unidirectional bearing 290 connected to the housing 210 may interface with the outer surface of the bit box 250 to allow the bit box 250 (as well as the hammer drive 260 and/or the mallet 230) to rotate in only a single direction (i.e., a second direction or free-wheel direction of the second unidirectional bearing 290) relative to the housing 210. The spiral gear 270 may rotate only in a first direction relative to the hammer drive 260 and the bit box may rotate only in a second direction, opposite the first direction, relative to the housing 210.

FIGS. 4A and 4B illustrate a proximal view of the first and second unidirectional bearings 280, 290, respectively, and further illustrate that the first and second unidirectional bearings 280, 290 may comprise sprag bearings. However, the first and second unidirectional bearings 280, 290 may comprise other bearings, such as roller ramp bearings, one-way bearings, or other unidirectional bearings. While the below description provides an explanation of how sprag bearings may be employed to control the rotation of the drive body 240, one skilled in the art will understand that other types of unidirectional bearings may be employed to provide similar rotational control of the drive body 240. In at least one embodiment, the first and second unidirectional bearings 280, 290 are opposite each other such that they rotate in opposite directions.

Each of the bearings 280, 290 may comprise a cylindrical wall 282, 292 configured to attach to a component of the drill-string apparatus 200 or may be otherwise rotationally constrained relative to a surface of the drill-string apparatus 200. Each of the bearings 280, 290 may also comprise a plurality of sprags 286, 296 extending radially inward from an inner surface 284, 294 of the bearings 280, 290 towards an underlying component (i.e., the bit box 250 or the hammer drive 260).

The sprags 286, 296 may have a length greater than the gap between the cylindrical wall 282, 292 and the underlying component and may be pivotably connected to the cylindrical wall 282, 292. The sprags 286, 296 may be configured to engage or interface with a surface of the underlying component. For example, the sprags 286, 296 may be biased by a spring towards the underlying component. The sprags 286, 296 may beneficially enable rotation of the underlying component in a first direction (e.g., rotation of the underlying component in direction D2 for first unidirectional bearing 280 and direction D3 for second unidirectional bearing 290) while preventing the underlying component from rotating in a second direction opposite the first direction.

In some embodiments, the bearings 280, 290 may each comprise a second cylindrical wall disposed within and having a diameter less than the cylindrical wall 282, 292. The second cylindrical walls may engage the sprags 286, 296 of the sprag bearings 280, 290 and may be configured to attach to the underlying component, such that the sprags 286, 296 do not engage the outer surfaces of the bit box 250 and hammer drive 260, respectively. In other embodiments, the sprags 286, 296 may engage the outer surfaces of the bit box 250 and hammer drive 260 directly, as described above.

FIGS. 4A and 4B each show proximal views of the first and second unidirectional bearings 280, 290. Importantly, the orientation of the first unidirectional bearing 280 may be mirrored relative to the second unidirectional bearing 290, such that the freewheeling direction of the first unidirectional bearing 280 is opposite the freewheeling direction of the second unidirectional bearing 290. Although specific orientations and couplings of the first and second unidirectional bearings 280, 290 are described above, the indexing function of the drill-string apparatus 200 does not depend on the precise locations of these bearings. One skilled in the art will recognize that the bearings may be inverted, reversed, or otherwise interchanged—such as by swapping the free-wheel and engaged directions or by attaching the bearings to opposite components of the drive body 240 or housing 210—while still producing the same relative indexing motion between the drive body 240 and the housing 210. All such inverted, reversed, or functionally equivalent arrangements are intended to be encompassed by this disclosure.

The drill-string apparatus 200 may comprise multiple first unidirectional bearings 280 and/or multiple second unidirectional bearings 290. The number of unidirectional bearings 280, 290 may be selected according to the torque requirements of the drill-string apparatus 200. In some embodiments, the drill-string apparatus 200 may comprise two first unidirectional bearings 280 and two second unidirectional bearings 290. In some embodiments, a first unidirectional bearing 280 may be disposed in gaps formed by the spiral gear 270 near the proximal and distal ends of the spiral gear 270, as illustrated in FIG. 3. In other embodiments, the drill-string apparatus 200 may comprise more than two first and second unidirectional bearings 280, 290, such as three, four, five, six, or more than six first and/or second unidirectional bearings 280, 290.

FIGS. 5 through 7 illustrate the drive body 240 (excluding the mallet 230), the housing 210, and the interaction therebetween. The spiral gear 270 of the drive body 240 may comprise a first helical spline 272 (shown in FIG. 7) extending from the outer surface of the spiral gear 270. A mating gear 220 may be attached to an inner surface 214 of the housing or integrally formed with the housing 210.

The mating gear 220 may comprise a second helical spline 222 configured to mate with the first helical spline 272. The first and second helical splines 272, 222 may cooperate to transmit an axial thrust of the spiral gear 270 into rotational movement. As the spiral gear 270 translates axially (proximally or distally), the first helical spline 272 engages the second helical spline 222 to rotate the spiral gear 270 relative to the housing 210.

One skilled in the art will understand that the orientation of the sprags 286, 296 may be mirrored on the first and second unidirectional bearings 280, 290, with the helical splines 272, 222 of the spiral and mating gears 270, 220 also mirrored, in order to form a drill-string apparatus 200 that may rotate or index in an opposite direction to that described above.

Rotation of the DTH Hammer

FIGS. 8A and 8B illustrate the drill-string apparatus 200 connected to the distal end of a drill string 100. The distal end of the drill string 100 may comprise a hammer 320 configured to strike the drill bit against virgin rock and to actuate the rotating mechanism of the drill-string apparatus 200. The hammer may comprise a breaker or a percussive hammer, for example. The hammer 320 may be actuated through use of a pressurized fluid delivered to the hammer 320 through the drill string 100. For example, the hammer 320 may be actuated through a hydraulic (e.g., water) or a pneumatic (i.e., air) mechanism, such that the drill-string apparatus 200 may comprise a hydraulic drill-string apparatus 200 or a pneumatic drill-string apparatus 200. In some embodiments the hammer 320 may be actuated with drilling mud. In some embodiments, pressurized fluid (e.g., water or air) expelled from the drill string 100 during or after a stroke of the hammer 320 may carry debris (e.g., dirt and/or cracked rock) out of the drilling hole.

The hammer 320 may be propelled distally in direction D4 (see FIG. 8B) by the pressurized fluid to strike the mallet 230 of the drive body 240. The stroke rate of the hammer 320 may be between 100 and 2500 beats per minute (bpm), while the indexing rotation of the drill bit may occur within a range from approximately 5 rotations per minute (rpm) to approximately 100 rpm, or from approximately 8 rpm to approximately 12 rpm, or may occur at 10 rpm, or may occur within a range having any two of the foregoing as endpoints.

FIGS. 9 through 11 illustrate a cross-sectional view of the drill-string apparatus 200 during actuation of the rotating mechanism. FIG. 9 illustrates the drill-string apparatus 200 immediately before the hammer 320 strikes the mallet 230 of the drill-string apparatus 200. As the hammer 320 strikes the mallet 230, the mallet 230 is pushed distally in direction D4 into the housing 210, as seen in FIG. 10. The force from the stroke of the hammer 320 is transmitted from the mallet 230 against the other components of the drive body 240, including the bit box 250, the hammer drive 260, and the spiral gear 270, such that the drive body 240 as a whole translates distally in direction D4. In this manner, a drill bit extending from the drill-string apparatus 200 is made to strike and crack the virgin rock lying distally from the drill-string apparatus 200.

However, the interlocking mechanism between the spiral gear 270 and the mating gear 220 prevents the spiral gear 270 from translating distally without a corresponding rotational movement in direction D5. Thus, the force from the hammer 320 forces the spiral gear 270 distally and the angled surfaces of the helical splines 272, 222 extending from the spiral gear 270 and the mating gear 220 cause the first helical spline 272 to turn, rotate, or twist in a first direction (i.e., direction D5 corresponding to the free-wheel direction of the first unidirectional bearing 280 and the engaged direction of the second unidirectional bearing 290) along the second helical spline 222.

Note that the first unidirectional bearings 280 disposed between the spiral gear 270 and the hammer drive 260 enables the spiral gear 270 to rotate relative to the hammer drive 260 in direction D5. However, the bit box 250 and the hammer drive 260 connected thereto are prevented from rotating in the direction D5 relative to the housing 210 by the second unidirectional bearings 290, the sprags 296 of the second unidirectional bearing 290 engaging the outer surface of the bit box 250. Thus, although the bit box 250 and hammer drive 260 are forced distally, these components do not rotate as the drive body 240 reciprocates toward the drill bit. Importantly, turning, rotating, or twisting of the first helical spline 272 relative to the second helical spline 222 in the first direction does not substantially absorb the force from the stroke of the hammer 320, such that at least a large majority of the force from the stroke is translated into propelling the drive body 240 and the drill bit 110 forward to strike and crush the virgin rock.

After the stroke of the hammer 320 causes drill bit to strike and/or crush the virgin rock, the drill-string apparatus 200 may be retracted into the housing 210. A weight of the drill string 100 above the drill bit may push against the drill-string apparatus 200, causing the drill-string apparatus 200 to push backward in direction D6 relative to the housing 210. This motion may also move the mallet 230 proximally back into position to receive another strike from the hammer 320 and may return the hammer 320 to a position for the next stroke.

Again, the angled surfaces of the helical splines 272, 222 of the spiral and mating gears 270, 220 prevent the spiral gear 270 from translating proximally or distally without a corresponding rotational movement. As the spiral gear 270 moves in the proximal direction D6 as part of the drive body 240, the spiral gear 270 rotates in a second direction (i.e., direction D7 corresponding to the engaged direction of the first unidirectional bearings 280 and the free-wheel direction of the second unidirectional bearings 290) opposite the first direction (i.e., opposite rotational direction D5). In this instance, the sprags 286 of the first unidirectional bearings 280 may now engage the outer surface of the hammer drive 260, preventing the spiral gear 270 from rotating relative to the hammer drive 260. Thus, as the spiral gear 270 is forced to rotate in direction D7 the hammer drive 260 is also caused to rotate in direction D7.

The physical coupling between the hammer drive 260 and the bit box 250 also causes the bit box 250 and the attached drill bit to rotate in direction D7. Note again, that while the sprags 296 of the second sprag bearings 290 engaged the outer surface of the bit box to prevent the bit box 250 and hammer drive 260 from rotating in direction D5 the sprags 296 of the second sprag bearings 290 enable the outer surface of the bit box 250 to rotate in direction D7. In this manner, energy from a retraction stroke of the drill-string apparatus 200 may cause a rotational displacement of the bit box 250, the hammer drive 260, and the drill bit without a corresponding rotation of the drill string 100.

The force from the stroke of the hammer 320 may be tailored to the drill-string apparatus 200 and the type of rock underneath, such that the drill bit is propelled distally in direction D4 at a specific distance. For example, each strike of the hammer 320 may push the drill bit forward a specific distance of approximately 0.5 inches, 0.375 inches, 0.25 inches, 0.125 inches, 0.0625 inches, or less than 0.0625 inches, or may push the drill bit forward within a range having any two of the foregoing values as endpoints.

Thus, the weight of the drill string 100 above the drill bit 110 may cause the drill string 100 to move a specific distance corresponding to the propelled distance of the drill bit 110. This specific distance may remain consistent as the drill bit 110 is propelled through the virgin rock. The angled surfaces of the helical splines 272, 222 may then cause the drive body 240 to index relative to the drill string 100 at a precise rotational movement according to the specific distance at which the drill bit 110 is propelled. The angle of the helical splines 272, 222 may also be configured according to the type and/or hardness of the virgin rock to achieve the desired indexing motion.

In some instances, the drill bit 110 may not be propelled to the desired specific distance necessary for the indexed rotation. For example, the drill bit 110 may encounter harder rock than expected, preventing effective distal translation of the drill bit 110 and preventing the precise indexing motion of the drive body 240. The drill-string apparatus 200 may comprise a compression spring (not shown) that acts to ensure precise indexing motion of the drill-string apparatus 200. If the drill bit 110 is prevented from moving forward despite the stroke of the hammer 320, the compression spring may absorb at least part of the force of the stroke, the housing 210 translating distally relative to the drive body 240 and causing an indexing rotation of the drive body 240 relative to the drill string 100. Thereafter, the compression spring may push against the housing 210 or drill string 100, pushing the drill string 100 back into position and translating the drive body 240 distally relative to the housing 210. The compression spring may also push against the drive body 240, exerting a force along the first helical spline 272 and causing the first helical spline 272 to rotate. The compression spring may be configured such that the spring does not absorb the force of the stroke unless the drill bit encounters virgin rock at or above a particular hardness threshold. The compression spring may be disposed within the drill-string apparatus 200, such as between a distal portion of the housing 210 and the bit box 250 or at another location within the drill-string apparatus 200.

The drill string 100 may also comprise a steering mechanism. For example, the drill string 100 may comprise a bend 105, as described above, such that rotation of the drill string 100 may steer the drilling direction of the drill bit 110.

Also disclosed is a method for operating an indexing down-the-hole hammer (IDTH) 200 as described above. The method may comprise activating the drill-string apparatus 100 to propel a drive body 240 forward, causing a first helical spline 272 to travel along a second helical spline 222 in a direction of free rotation of a first unidirectional bearing 280 that is coupled to the first helical spline 272.

The first unidirectional bearing 280 may be attached to a hammer drive 260 of the drill-string apparatus 200. Travel of the first helical spline 272 distally in a direction of free rotation may then cause a weight on a drill bit 110 to force the hammer drive 260 of the drill-string apparatus 200 to retract, and, during the retract motion, cause the first helical spline 272 to travel along the second helical spline 222 in a direction of engaged rotation of the first unidirectional bearing 280. Rotation of the first unidirectional bearings 280 engaged with the bit box 250 may then cause an indexed rotational displacement of the drill bit 110.

Another method for operating a drill string apparatus 200 may comprise providing a drill string apparatus 200, wherein the drill string apparatus 200 comprises a drill string 100 and a drill string apparatus. As used herein, the drill string apparatus may also be referred to as an “indexing down-the-hole (IDTH) hammer” 200. The method may further comprise activating the IDTH Hammer 200 to drill forward. Activating the IDTH hammer 200 may cause at least a portion of the IDTH hammer 200 to rotate. However, during activation of the IDTH Hammer 200 the drill string 100 may not rotate or rock.

The drill string 100 may comprise a bent housing and the direction of the bent housing (i.e., the orientation in which the housing bends) may be maintained such that the bent housing is not rotated. The bore formed by the drill string 100 may comprise vertical bore or horizontal directional bore drilling. Activation of the IDTH Hammer 200 may comprise forward circulation or reverse circulation boring.

The method may comprise directionally steering a rotary borehole. Steering may be accomplished without rocking the drill bit 110 and/or without employing a carve steering technique. Specifically, the method may enable horizontal directional drilling using traditional directional drilling techniques. The method may further comprise use of a surveying instrument, or a rod communication system to facilitate location of the drill bit to an operator. The rod communication system may transmit data relayed from a survey instrument from a downhole position to the uphole position to give the operator the location of the drill bit 110 to directionally steer the borehole.

FIG. 12 illustrates a skid steer loader 400 that may employ the drill-string apparatus 200 described above. Specifically, a jack hammer 410 (i.e., “control body”) of the loader 400 may employ the drill-string apparatus 200 to rotate a head (i.e., “reciprocating drive end”) of the jack hammer 410. Thus, the drill-string apparatus 200 may also be used in other contexts, including digging, mining, excavating, construction equipment (e.g., electric-motor drills), or other indexed-rotation apparatus.

The present invention may be embodied in other specific forms without departing from its spirit or characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.

The disclosed technology is illustrated, for example, according to various clauses described below. Various examples of features of the disclosed technology are described as numbered clauses (1, 2, 3, etc.) for convenience. These are provided as examples and do not limit the disclosed technology. It is noted that any of the dependent features may be combined in any combination and placed into a respective independent features. The other features can be presented in a similar manner.

• • Clause 1. A drill-string apparatus comprising: a physical coupling between a down-the-hole (DTH) hammer and a drill bit; a first helical spline physically coupled to the drill bit; and a second helical spline coupled to the first helical spline and physically connected to a drill string, wherein the drill-string apparatus is configured such that a reciprocating displacement of the DTH hammer causes rotational displacement of the drill bit via movement of the first helical spline along the second helical spline.
  • Clause 2. The drill-string apparatus of any of the preceding clauses, wherein a unidirectional bearing translates axial thrust of the DTH hammer into a rotational movement.
  • Clause 3. The drill-string apparatus of any of the preceding clauses, further comprising: a first unidirectional bearing attached to a drive of the DTH hammer, wherein the first unidirectional bearing is coupled to the first helical spline or the second helical spline.
  • Clause 4. The drill-string apparatus of any of the preceding clauses, further comprising: a second unidirectional bearing attached to a housing of the DTH hammer.
  • Clause 5. The drill-string apparatus of any of the preceding clauses, wherein the drill-string apparatus is configured such that when the DTH hammer reciprocates toward the drill bit, the first helical spline is pushed forward and twists along the second helical spline in a first direction, the first direction comprising a free-wheel direction of the first unidirectional bearing and an engaged direction of the second unidirectional bearing.
  • Clause 6. The drill-string apparatus of any of the preceding clauses, wherein the drill-string apparatus is configured such that after the DTH hammer reciprocates toward the drill bit, a weight of the drill string on the drill bit causes the DTH hammer to push backward and twist along the second helical spline in a second direction, the second direction comprising an engaged direction of the first unidirectional bearing and a free-wheel direction of the second unidirectional bearing.
  • Clause 7. The drill-string apparatus of any of the preceding clauses, wherein the second unidirectional bearing is configured to only allow for indexing motion in the second direction while preventing rotation of the drill bit in the first direction.
  • Clause 8. The drill-string apparatus of any of the preceding clauses, wherein the unidirectional bearing comprises a sprag bearing or roller ramp bearing.
  • Clause 9. The drill-string apparatus of any of the preceding clauses, wherein the DTH hammer comprises a hydraulic hammer.
  • Clause 10. The drill-string apparatus of any of the preceding clauses, wherein the DTH hammer comprises a pneumatic hammer.
  • Clause 11. The drill-string apparatus of any of the preceding clauses, wherein the drill-string apparatus is configured to use energy from a retraction stroke of the DTH hammer to cause the rotational displacement of the drill bit.
  • Clause 12. The drill-string apparatus of any of the preceding clauses, wherein a compression spring is positioned to exert a force along the first helical spline.
  • Clause 13. The drill-string apparatus of any of the preceding clauses 1, wherein the drill string comprises a steering mechanism.
  • Clause 14. The drill string apparatus of any of the preceding clauses, wherein the drill string comprises a survey instrument which tracks bend orientation.
  • Clause 15. An indexed-rotation apparatus attached to a hydraulic breaker, jack hammer, or other reciprocating tool the indexed-rotation apparatus comprising: a physical coupling between a control body and a reciprocating drive end; a first unidirectional bearing attached to a control body, wherein the first unidirectional bearing is coupled to the reciprocating drive end; and a second unidirectional bearing attached to a housing of the apparatus, wherein: the indexed-rotation apparatus is configured such that when the drive end reciprocates, the first unidirectional bearing turns in a free-wheel direction and the second unidirectional bearing turns in an engaged direction.
  • Clause 16. The indexed-rotation apparatus of any of the preceding clauses, wherein the first and second unidirectional bearings translate axial thrust of the control body into a rotational movement.
  • Clause 17. The indexed-rotation apparatus of any of the preceding clauses, wherein the indexed-rotation apparatus is configured such that when the hammer reciprocates toward the bit, the first unidirectional bearing turns in an engaged direction and the second unidirectional bearing turns in a free-wheel direction.
  • Clause 18. The indexed-rotation apparatus of any of the preceding clauses, wherein the second unidirectional bearing is configured to only allow for indexing motion in a second direction while preventing rotation of the bit in a first direction.
  • Clause 19. The indexed-rotation apparatus of any of the preceding clauses, wherein the indexed-rotation apparatus is configured to use energy from a retraction stroke of the indexed-rotation apparatus to cause a rotational displacement of the bit.
  • Clause 20. The indexed-rotation apparatus of any of the preceding clauses, wherein the hammer comprises a percussive top hammer.
  • Clause 21. A method for operating an indexing down-the-hole hammer (IDTH) comprising: activating the IDTH hammer to propel a drive body forward; causing a first helical spline to travel along a second helical spline in a direction of free rotation of a first unidirectional bearing that is coupled to the first helical spline, wherein the first unidirectional bearing is attached to a hammer drive of the drive body; causing a weight on a drill bit to force the hammer drive of the drive body to retract; and during a retract motion, causing the first helical spline to travel along the second helical spline in a direction of engaged rotation of the first unidirectional bearing, the engaged first unidirectional bearing causing an indexed rotational displacement of the drill bit, the displacement maintained by the second unidirectional bearing.
  • Clause 22. A method for operating a drill string apparatus, the method comprising: providing a drill string apparatus, wherein the drill string apparatus comprises a drill string and an indexing down-the-hole (IDTH) hammer; and activating the IDTH Hammer to drill forward by causing at least a portion of the IDTH hammer to rotate; wherein during activating of the IDTH Hammer, the drill string does not rotate or rock.
  • Clause 23. The method for operating a drill string apparatus of any of the preceding clauses, wherein the drill string comprises a bent housing, and the direction of the bent housing is maintained such that the bent housing is not rotated.
  • Clause 24. The method for operating a drill string apparatus of any of the preceding clauses, wherein a bore formed by the drill string apparatus comprises vertical bore or horizontal directional bore drilling.
  • Clause 25. The method of any of the preceding clauses, wherein the drill string apparatus comprises a survey instrument which tracks bend orientation.
  • Clause 26. The method for operating a drill string apparatus of any of the preceding clauses, wherein activating the IDTH Hammer comprises forward circulation or reverse circulation boring.