DRILLING APPARATUS WITH SHUTTER

This application is being filed on 15 Mar. 2010, as a PCT International Patent application in the name of Vermeer Manufacturing Company, a U.S. national corporation, applicant for the designation of all countries except the US, and Keith Allen Hoelting, a citizen of the U.S., Andis Salins and Stuart Harrison, both citizens of Australia, applicants for the designation of the US only.

TECHNICAL FIELD

The present disclosure relates generally to trenchless drilling equipment. More particularly, the present disclosure relates to drilling equipment capable of maintaining a precise grade and line.

BACKGROUND

Modern installation techniques provide for the underground installation of services required for community infrastructure. Sewage, water, electricity, gas and telecommunication services are increasingly being placed underground for improved safety and to create more visually pleasing surroundings that are not cluttered with visible services.

One method for installing underground services involves excavating an open trench. However, this process is time consuming and is not practical in areas supporting existing construction. Other methods for installing underground services involve boring a horizontal underground hole. However, most underground drilling operations are relatively inaccurate and unsuitable for applications on grade and on line.

PCT International Publication No. WO 2007/143773 discloses a micro-tunneling system and apparatus capable of boring and reaming an underground micro-tunnel at precise grade and line. While this system represents a significant advance over most prior art systems, further enhancements can be utilized to achieve even better performance.

SUMMARY

One aspect of the present disclosure relates to a drilling apparatus including a cutting unit defining at least one through-hole that provides fluid communication between a distal side and a proximal side of the cutting unit. In use, spoils generated by the cutting unit can be drawn through the through-hole by a vacuum of the drilling apparatus. The cutting unit also includes a flow-control shutter. In certain embodiments, the shutter is movable between a first position where the through-hole is blocked/closed and a second position where the through-hole is open/unblocked. In other embodiments, the shutter can be used to only partially block the through-hole. By selecting the portion/percentage of the through-hole that is blocked by the shutter it is possible to enhance drilling performance by customizing the open transverse cross-sectional area of the through-hole to match the type of geologic material in which the drilling apparatus is being used.

Another aspect of the present disclosure relates to a drilling apparatus (i.e., a tunneling apparatus) adapted for use in flowable conditions (e.g., drilling environments below the water table). In certain embodiments, the drilling apparatus includes a drill string having a proximal end and a distal end. A cutting unit is mounted at the distal end of the drill string. The cutting unit is powered by a drive mechanism at the proximal end of the drill string. The drive mechanism is adapted to provide torque for rotating a cutting component of the cutting unit and is also adapted for applying thrust to the drill string to drive the drill string and the cutting unit distally into the ground. The drill string defines a vacuum passage for evacuating spoils generated by the cutting component within a bore being drilled. The drill string also defines an air passage for providing air down the bore during drilling to reduce the likelihood of plugging of the vacuum passage. The cutting component defines through-holes that provide fluid communication between the vacuum passage and a cutting side (i.e., a distal side) of the cutting component. The through-holes also provide fluid communication between the air passage and the cutting side of the cutting component. The cutting unit further includes a shutter for selectively opening and closing the through-holes. During normal drilling operations in flowable conditions, the through-holes are open thereby allowing: a) spoils generated at the cutting side of the cutting component to readily be drawn through the through-openings and into the vacuum passage; and b) air from the air passage to flow to the cutting side of the cutting component. When drilling operations are stopped, the shutter is used to close (i.e., block, cover, etc.) the through-holes to prevent flowable material at the cutting side of the cutting component from filling the vacuum passage and/or the air passage.

A variety of additional aspects will be set forth in the description that follows. The aspects can relate to individual features and to combinations of features. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the broad inventive concepts upon which the embodiments disclosed herein are based.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic depiction of a drilling apparatus having features in accordance with the principles of the present disclosure;

FIG. 2 is a side view of a drill head in accordance with the principles of the present disclosure;

FIG. 3 is a perspective view of the drill head of FIG. 2 showing a cutting side (i.e., a distal side) of a rotational cutting component located at a distal end of a cutting unit of the drill head;

FIG. 4 is a perspective view showing a shutter located at a proximal end of the cutting unit of FIG. 3, the shutter and rotational cutting component are shown in a first relative position in which fluid communication between the distal end and the proximal end of the cutting unit is open;

FIG. 5 is a perspective view showing the shutter and the rotational cutting component of the cutting unit of FIG. 3 in a second relative position in which fluid communication between the distal end and the proximal end of the cutting unit is open;

FIG. 6 is a front, exploded perspective view of another cutting unit in accordance with the principles of the present disclosure;

FIG. 7 is a rear, exploded perspective view of the cutting unit of FIG. 6;

FIG. 8 is a cross-sectional view of an assembled version of the cutting unit of FIG. 6;

FIG. 9 is a front view of the cutting unit of FIG. 6 in a fully-open flow orientation;

FIG. 10 is a rear view of the cutting unit of FIG. 6 in the fully-open configuration;

FIG. 11 is a front view of the cutting unit of FIG. 6 in a partially open flow configuration;

FIG. 12 is a rear view of the cutting unit of FIG. 6 in the partially open flow configuration;

FIG. 13 is a front, perspective, exploded view of a further cutting unit in accordance with the principles of the present disclosure;

FIG. 14 is a rear, perspective, exploded view of the cutting unit of FIG. 13; and

FIG. 15 is a cross-sectional view of an assembled version of the cutting unit of FIG. 13.

DETAILED DESCRIPTION
A. Overview of Example Drilling Apparatus

FIG. 1 shows a drilling apparatus 20 having features in accordance with the principles of the present disclosure. Generally, the apparatus 20 includes a plurality of pipe sections 22 that are coupled together in an end-to-end relationship to form a drill string 24. Each of the pipe sections 22 includes a drive shaft 26 rotatably mounted in an outer casing assembly 28. A drill head 30 is mounted at a distal end (i.e., a front end) of the drill string 24 while a drive unit 32 is located at a proximal end (i.e., a back or rear end) of the drill string 24. The drive unit 32 includes a torque driver adapted to apply torque to the drill string 24 and an axial driver for applying thrust or pull-back force to the drill string 24. Thrust or pull-back force from the drive unit 32 is transferred between the proximal end and the distal end of the drill string 24 by the outer casing assemblies 28 of the pipe sections 22. Torque is transferred from the proximal end of the drill string 24 to the distal end of the drill string 24 by the drive shafts 26 of the pipe sections 22 which rotate relative to the casing assemblies 28. The torque from the drive unit 32 that is transferred through the apparatus 20 by the drive shafts 26 is ultimately used to rotate a cutting unit 34 of the drill head 30.

The pipe sections 22 can also be referred to as drill rods, drill stems or drill members. The pipe sections are typically used to form an underground bore, and then are removed from the underground bore when product (e.g., piping) is installed in the bore.

The drill head 30 of the drilling apparatus 20 can include a drive stem 46 rotatably mounted within a main body 38 of the drill head 30. The main body 38 can include a one piece body, or can include multiple pieces or modules coupled together. A distal end of the drive stem 46 is configured to transfer torque to the cutting unit 34. For example, the distal end of the drive stem 46 can include a male torque driver 49 (e.g., a hexagonal driver) that fits within a torque driver receptacle 51 of the cutting unit 34 (e.g., a hexagonal female socket of the cutting unit 34). A proximal end of the drive stem 46 couples to the drive shaft 26 of the distal-most pipe section 22 such that torque is transferred from the drive shafts 26 to the drive stem 46. In this way, the drive stem 46 functions as the last leg for transferring torque from the drive unit 32 to the cutting unit 34. The outer casing assemblies 28 transfer thrust and/or pull back force to the main body 38 of the drill head. The drill head 30 preferably includes bearings (e.g., axial/thrust bearings and radial bearings) that allow the drive stem 46 to rotate relative to the main body 38 and also allow thrust or pull-back force to be transferred from the main body 38 through the drive stem 46 to the cutting unit 34.

In certain embodiments, the drilling apparatus 20 is used to form underground bores at precise grades. For example, the drilling apparatus 20 can be used in the installation of underground pipe installed at a precise grade. In some embodiments, the drilling apparatus 20 can be used to install underground pipe or other product having an outer diameter less than 600 mm or less than 300 mm.

It is preferred for the drilling apparatus 20 to include a steering arrangement adapted for maintaining the bore being drilled by the drilling apparatus 20 at a precise grade and line. For example, referring to FIG. 1, the drill head 30 includes a steering shell 36 mounted over the main body 38 of the drill head 30. Steering of the drilling apparatus 20 is accomplished by generating radial movement between the steering shell 36 and the main body 38 (e.g., with radially oriented pistons, one or more bladders, mechanical linkages, screw drives, etc. positioned between the steering shell 36 and the main body 38). Further details about suitable steering systems are provided in U.S. Provisional Patent Application No. 61/246,616, filed Sep. 29, 2009, that is hereby incorporated by reference in its entirety.

Steering of the drilling apparatus 20 is preferably conducted in combination with a guidance system used to ensure the drill string 24 proceeds along a precise grade and line. For example, as shown at FIG. 1, the guidance system includes a laser 40 that directs a laser beam through a continuous axially extending air passage 43 defined by the outer casing assemblies 28 of the pipe sections 22 to a target located adjacent the drill head 30. The air passage extends from the proximal end to the distal end of the drill string 24 and allows air to be provided to the cutting unit 34. An air pressure source 45 can be used to force air distally through the passage 43.

The drilling apparatus 20 also includes an electronic controller 50 (e.g., a computer or other processing device) linked to a user interface 52 and a monitor 54. The user interface 52 can include a keyboard, joystick, mouse or other interface device. The controller 50 can also interface with a camera 60 such as a video camera that is used as part of the steering system. For example, the camera 60 can generate images of the location where the laser beam hits the target. It will be appreciated that the camera 60 can be mounted within the drill head 30 or can be mounted outside the drilling apparatus 20 (e.g., adjacent the laser 40). If the camera 60 is mounted at the drill head 30, data cable can be run from the camera through a passage that runs from the distal end to the proximal end of the drill string 24 and is defined by the outer casing assemblies 28 of the pipe sections 22. In still other embodiments, the drilling apparatus 20 may include wireless technology that allows the controller to remotely communicate with the down-hole camera 60.

During steering of the drilling apparatus 20, the operator can view the camera-generated image showing the location of the laser beam on the target via the monitor 54. Based on where the laser beam hits the target, the operator can determine which direction to steer the apparatus to maintain a desired line and grade established by the laser beam. The operator steers the drill string 24 by using the user interface to cause a shell driver 39 to modify the relative radial position of the steering shell 36 and the main body 38 of the drill head 30. In one embodiment, a radial steering force/load is applied to the steering shell 36 in the radial direction opposite to the radial direction in which it is desired to turn the drill string. For example, if it is desired to steer the drill string 24 upwardly, a downward force can be applied to the steering shell 36 which forces the main body 38 and the cutting unit 34 upwardly causing the drill string to turn upwardly as the drill string 24 is thrust axially in a forward/distal direction. Similarly, if it is desired to steer downwardly, an upward force can be applied to the steering shell 36 which forces the main body 38 and the cutting unit 34 downwardly causing the drill string 24 to be steered downwardly as the drill string 24 is thrust axially in a forward/distal direction.

To assist in drilling, the drilling apparatus 20 can also include a fluid pump for forcing drilling fluid from the proximal end to the distal end of the drill string 24. In certain embodiments, the drilling fluid can be pumped through a central passage defined through the drive shafts 26. The central passage defined through the drive shafts 26 can be in fluid communication with a plurality of fluid delivery ports provided at the cutting unit 34 such that the drilling fluid is readily provided at a cutting face of the cutting unit 34. Fluid can be provided to the central passage though a fluid swivel located at the drive unit 32. In other embodiments, a drilling fluid line can be routed from the proximal end to the distal end of the drill string through a separate channel defined by the drill string.

The drilling apparatus 20 can also include a vacuum system for removing spoils and drilling fluid from the bore being drilled. For example, the drill string 24 can include a vacuum passage 47 that extends continuously from the proximal end to the distal end of the drill string 24. The proximal end of the vacuum passage can be in fluid communication with a vacuum 65 and the distal end of the vacuum passage is typically directly behind the cutting unit 34 adjacent the bottom of the bore. The vacuum 65 applies vacuum pressure to the vacuum passage 47 to remove spoils and liquid from the bore being drilled. At least some air provided to the distal end of the drill string 24 through the air passage 43 is also typically drawn into the vacuum passage to assist in preventing plugging of the vacuum passage. In certain embodiments, the liquid and spoils removed from the bore though the vacuum passage can be delivered to a storage tank 67.

B. Example Cutting Units

FIG. 2 is a side view of a distal portion of the drill head 30 of the drilling apparatus 20 of FIG. 1. Specifically, FIG. 2 shows the steering shell 36 and the cutting unit 34 of the drill head 30. The cutting unit 34 includes a proximal end 70 (i.e., a back or rear end) positioned directly adjacent to a distal end of the steering shell 36 and a distal end 72 (i.e., a front end) distally offset from the steering shell 36.

Referring to FIG. 3, the cutting unit 34 includes a rotational cutting component 74 that is rotated about a central longitudinal axis 75 (see FIGS. 4 and 5) of the cutting unit 34 to facilitate cutting a bore with the drilling apparatus 20. The axis 75 can be co-axially aligned with the central longitudinal axis defined by the drive shafts 26 of the pipe sections 22. Specifically, the rotational cutting component 74 is rotated about the axis 75 via torque transferred from the drive unit 32 by the drive shafts 26. During drilling operations, the rotational cutting component 74 is typically rotated about the axis 75 relative to the steering shell 36 of the drill head 30, the main body 38 of the drill head 30 and the casing assemblies 28 of the pipe sections 22.

Referring to FIGS. 3 and 4, the rotational cutting component 74 includes an outer rim 76 (e.g., a cylindrical outer rim) that extends generally from the distal end 72 to the proximal end 70 of the cutting unit 34. The rotational cutting component 74 also includes a front cutter mounting plate 78 (e.g., an annular mounting plate) non-rotationally connected to the outer rim 76 adjacent the distal end 72 of the cutting unit 34. The phrase “non-rotationally connected” means that the connection does not allow relative rotation between the interconnected pieces. For example, the front cutter mounting plate 78 can be welded to the outer rim 76. Alternatively, the front cutter mounting plate 78 can be unitarily cast with the outer rim 76, machined as an integral part with the outer rim 76 or attached to the outer rim 76 with fasteners. As shown at FIG. 3, an outer peripheral portion 77 of the front cutter mounting plate 78 is non-rotationally connected to the outer rim 76.

Referring to FIG. 4, the rotational cutting component 74 also includes an inner hub 80 that is non-rotationally connected to an inner portion of the front cutter mounting plate 78. The inner hub 80 defines the torque driver receptacle 51 adapted for receiving the male torque driver 49 provided at the distal end of the drive stem 46 of the drill head 30. Thus, the inner hub 80 is configured to allow torque to be readily transferred from the drive stem 46 of the drill head 30 to the rotational cutting component 74 of the cutting unit 34.

The rotational cutting component 74 of the cutting unit 34 also includes a plurality of cutting elements mounted at a cutting side 82 (i.e., a distal side) of the front cutter mounting plate 78. The cutting elements include cutting teeth 84 and cutting blades 86a attached to the cutting side 82 of the front cutter mounting plate 78. The cutting blades 86a are mounted adjacent to through-holes 88 that extend through the front cutter mounting plate 78 in a distal-to-proximal direction. The cutting blades 86a are secured to mounting blocks 89 that are secured by fasteners within pockets defined by the front cutting side 82 of the rotational cutting component 74. The cutting blades 86a and/or the mounting blocks 89 can be configured to cover at least portions of the through-holes 88. In this way, by using different cutting blades 86a or different sized mounting blocks 89, the maximum available size of the open portions of the through-holes 88 can be varied to customize the cutting unit 34 to the type of material through which the cutting unit 34 is drilling.

The through-holes 88 allow spoils generated by the cutting elements of the cutting unit 34 to pass in a distal-to-proximal direction through the cutting unit 34. Once the cuttings have passed through the through-holes 88, the cuttings are drawn into the vacuum passage 47 and removed from the bore being drilled. In certain embodiments, the through-holes 88 can also allow air to pass in a proximal-to-distal direction through the cutting unit 34 where the air mixes with the cuttings and is then drawn along with the cuttings back through the through-holes 88 in a distal-to-proximal direction to the vacuum passage 47.

When drilling in flowable conditions (e.g., below water table conditions), it may be desirable to be able to selectively open and close the through-holes 88. When the through-holes 88 are closed, fluid communication between the distal end 72 and the proximal end 70 of the cutting unit 34 is blocked so that material on the distal side of the front cutter mounting plate 78 is prevented from flowing through the through-holes 88 and filling the vacuum passage 47 and/or the air passage 43.

Referring to FIGS. 4 and 5, the cutting unit 34 also includes a shutter 90 for selectively opening and closing the through-holes 88. FIGS. 4 and 5 show the shutter 90 as an annular plate mounted at the proximal end 70 of the cutting unit 34. The shutter 90 includes through-holes 91 that are circumferentially separated from one another by blocking portions 92. The shutter 90 also defines arcuate slots 93 that are defined through the blocking portions 92. The slots 93 define radiuses of curvature that are swung about a center line that extends along the axis of rotation 75. Fasteners 94 (e.g., shoulder bolts or pins) extend through the slots 93 and function to attach the shutter 90 to the proximal side of the front cutter mounting plate 78. The shutter 90 is mounted inside the proximal end of the outer rim 76. The fasteners 94 and slots 93 allow the shutter 90 and the rotational cutting component 74 to rotate relative to one another about the axis 75 between a first relative position shown in FIG. 4 and a second relative position shown in FIG. 5. In the first relative position of FIG. 4, the through-holes 91 of the shutter 90 align with the through-holes 88 of the rotational cutting component 74 such that fluid communication is open between the proximal and distal ends 70, 72 of the cutting unit 34. In the second relative position of FIG. 5, the blocking portions 92 of the shutter 90 cover the through-holes 88 of the rotational cutting component 74 such that fluid communication is blocked between the distal and proximal ends 72, 70 of the cutting unit 34.

The cutting unit 34 also includes a retention assembly 23 for retaining the cutting unit 34 on the drive shaft 46 by preventing the cutting unit from sliding distally off of the torque driver 49. The retention assembly 23 includes a retaining cap 25, a fastener 27 and a central cutting blade 86b. The central cutting blade 86b is attached to a head of the fastener 27. The fastener 27 extends through the retaining cap 25 and connects to the end of the drive shaft 46. For example, the fastener 27 can include a bolt having a threaded shaft that threads into an internally threaded axial opening defined by the male torque driver 49 of the drive stem 46. When the fastener 27 threads into a threaded opening of the male torque driver 49 (see FIG. 1), the fastener 27 causes the back side of the retaining cap 25 to compress/abut against the front side of the rotational cutting component 74 thereby preventing the cutting component 74 from sliding axially off of the male torque driver 49.

During normal drilling operations, the cutting unit 34 is rotated in a first rotational direction 95 about the axis of rotation 75. Rotation of the rotational cutting component 74 in the first rotational direction 95 causes the fasteners 94 to slide within the slots 93 to first ends 96 of the slots 93. With the fasteners 94 located at the first ends 96 of the slots 93, the shutter 90 and the rotational cutting component 74 are in the first relative position in which fluid communication is provided between the distal and proximal ends 72, 70 of the cutting unit 34 (see FIG. 4). As the rotational cutting component 74 continues to be rotated in the first rotational direction 95 while the fasteners 94 are located at the first ends 96 of the slots 93, torque is transferred from the rotational cutting component 74 through the fasteners 94 to the shutter 90. In this way, the shutter 90 rotates in unison with the rotational cutting component 74 such that the through-holes 88 remain open.

When drilling operations stop, it may be desirable to close fluid communication between the distal and proximal ends 72, 70 of the cutting unit 34. To accomplish this, the rotational cutting component 74 is rotated in a second rotational direction 97 about the axis of rotation 75. As this occurs, the slots 93 and the fasteners 94 allow the rotational cutting component 74 to rotate relative to the shutter 90 about the axis 75 from the first relative position of FIG. 4 to the second relative position of FIG. 5. In the second relative position of FIG. 5, the fasteners 94 engage second ends 98 of the slots 93 and the blocking portions 92 of the shutter 90 cover the through-holes 88 of the rotational cutting component 74. To reopen the through-holes, the rotational cutting component 78 is merely rotated in the first direction 95 about the axis of rotation 75 causing the rotational cutting component 74 to move back to the position of FIG. 4.

In alternative embodiments, rather than being used to open and close through-holes, shutters in accordance with the principles of the present disclosure can be used to adjust the size (e.g., the open transverse cross-sectional area) of cutter through-holes to customize the through-holes to accommodate drilling in a particular type of material. For example, FIGS. 6-12 show a cutting unit 134 including a rotational cutting component 174 and a shutter 190. The rotational cutting component 174 has a front cutting side 182 positioned opposite from a back side 183. A plurality of cutting teeth are provided at the front cutting side 182, and a plurality of through-holes 188 extend through the rotational cutting component 174 from the front cutting side 182 to the back side 183. The back side 183 of the rotational cutting component 174 includes a hub 180 defining a torque driver receptacle 151 adapted for receiving the male torque driver 49 provided at the distal end of the drive stem 46 of the drill head 30. The hub 180 is configured to allow torque to be readily transferred from the drive stem 46 of the drill head 30 to the rotational cutting component 174 of the cutting unit 134. In the depicted embodiment, the torque driver receptacle 151 is shown as a torque transfer socket including a plurality of flats. A retention assembly 123 fastens to the torque driver 49 to prevent the cutting unit 134 from sliding distally off of the torque driver 49. The retention assembly 123 includes a retaining cap 125 and a fastener 127. The fastener 127 extends through the retaining cap 125 and is adapted to connect to the torque driver 49. When the fastener 127 is tightened, a back side of the retaining cap 125 clamps against the front side of the rotational cutting component 174.

The shutter 190 of the cutting unit 134 is secured to the back side 183 of the rotational cutting component 174 by a plurality of fasteners 161. As shown at FIG. 6, the fasteners 161 are depicted as bolts that are threaded into tapped openings provided at the back side 183 of the rotational cutting component 174. The fasteners 161 extend through slots 193 defining radiuses of curvature that are swung about a centerline that extends along an axis of rotation 175. When the fasteners 161 are loosened, the slots 193 allow the rotational cutting component 174 and the shutter 190 to be rotated relative to one another about the axis of rotation 175. In contrast, when the fasteners 161 are tightened, the rotational cutting component 174 and the shutter 190 are locked in position relative to one another such that relative rotational movement between the rotational cutting component 174 and the shutter 190 about the axis of rotation 175 is prevented.

The shutter 190 includes through-holes 191 and blocking portions 192. By rotating the rotational cutting component 174 and the shutter 190 relative to one another about the axis of rotation 175, the relative position between the through-holes 188 of the rotational cutting component 174 and the through-holes 191 of the shutter 190 can be altered. In this way, the amount of open transverse cross-sectional area provided by the through-holes 188 can be adjusted. For example, the rotational cutting component 174 and the shutter 190 can be locked in a first relative rotational position (i.e., a fully closed position) (not shown) in which the blocking portions 192 of the shutter 190 fully block the through-holes 188 such that material is prevented from passing through the rotational cutting component 174. The rotational cutting component 174 and the shutter 190 can also be locked in a second rotational position (a fully open position) (see FIGS. 9 and 10) in which the through-holes 188 fully align with the through-holes 191 so that no portions of the through-holes 188 are blocked. In this position, a maximum open transverse cross-sectional area is provided by the through-holes 188 for allowing material to pass through the rotational cutting component 174.

The rotational cutting component 174 and the shutter 190 can also be locked at intermediate positions between the fully open position and the fully closed position. In an intermediate position, the shutter 190 only partially blocks the through-holes 188, thereby providing a reduced transverse cross-sectional area through which material can flow as compared to the fully open position. In certain embodiments, the shutter 190 blocks 10-90 percent of the transverse cross-sectional area of the through-holes 188, or 20-80 percent of the transverse cross-sectional area of the through-holes 188, or 20-60 percent of the transverse cross-sectional area of the through-holes 188 when in selected intermediate relative rotational positions. It will be appreciated that the intermediate relative rotational position can be selected by the operator so that the open portions of the transverse cross-sectional areas of the through-holes 188 are selected to match the type of material through which the drilling apparatus is intended to be drilled, thereby customizing the drilling head to the material intended to be drilled. The fasteners 161 allow the rotational cutting component 174 and the shutter 190 to be locked at an infinite number of intermediate relative rotational positions. Once the intermediate relative rotational position has been set, the fasteners maintain the rotational cutting component 174 and the shutter 190 in the selected intermediate relative rotational position during drilling. FIGS. 11 and 12 show the rotational cutting component 174 and the shutter 190 locked in an example intermediate relative rotational position in which the through-holes 188 are partially blocked by the shutter 190.

The cutting unit 134 is shown including a nut 135 for securing the retention assembly 123 to the rotational cutting component 174 during storage and shipping. It will be appreciated that the nut 135 is removed and discarded when the cutting unit 134 is mounted to the drill head 30.

FIGS. 13-15 show still another cutting unit 234 in accordance with the principles of the present disclosure. The cutting unit 234 includes a rotational cutting component 274 and a shutter 290. The rotational cutting component 274 includes a front cutting side 282 positioned opposite from a back side 283. Through-holes 288 extend through the rotational cutting component 274 from the cutting side 282 to the back side 283. Cutter mounting pockets 285 are provided at the front side 282 of the rotational cutting component 274 adjacent to the through-holes 288. The cutter mounting pockets allow cutter mounting blocks 289 to be readily mounted to the rotational cutting component 274 adjacent to the through-holes 288. Cutters such as elongated blades are secured to the cutter mounting blocks 289. By selecting different sizes of cutter mounting blocks and/or cutters, the maximum possible open areas of the through-holes 288 can be modified. For example, the through-holes 288 have a maximum open transverse cross-sectional area when the cutter mounting blocks and the cutters attached thereto do not overlap the through-holes 288. By selecting cutter mounting blocks and/or cutters with a predetermined amount of overlap with respect to the through-holes 288, the maximum open transverse cross-sectional area provided by the through-holes 288 can be adjusted.

The shutter 290 of the cutting unit 234 includes a hub 235 defining a torque driver receptacle 251 adapted for receiving the male torque driver 49 provided at the distal end of the drive stem 46 of the drill head 30. The torque driver receptacle 251 is configured to allow torque to be readily transferred from the drive stem 46 of the drill head 30 to the shutter 290. In the depicted embodiment, torque driver receptacle 251 includes a socket configuration including a plurality of flats. A retention assembly 223 is used to prevent the rotational cutting component 274 and the shutter 290 from sliding distally off of the torque driver 49. The retention assembly 223 includes a retaining cap 225, a fastener 227 and a central cutting blade 286b. The central cutting blade 286b is attached to a head of the fastener 227. The fastener 227 extends through the retaining cap 225 and connects to the end of the drive shaft 46. For example, the fastener 227 can include a bolt having a threaded shaft that threads into an internally threaded axial opening defined by the male torque driver 49 of the drive stem 46.

The retaining cap 225 is configured to retain the rotational cutting component 274 and the shutter 290 on the drive shaft 46 without clamping the rotational cutting component in place relative to the shutter 290. For example, the retaining cap 225 includes a hub portion 221 and a flange portion 219 that projects radially outwardly from a front end of the hub portion 221. The rear end of the hub portion 221 defines a shutter clamping surface 221a that engages a front face of the hub 235 of the shutter 290 when the fastener 227 is threaded into the drive shaft 46 to retain the shutter 290 on the drive shaft 46. The rear side of the flange portion 219 defines a rotational cutting component retention surface 219a that opposes the front side of the rotational cutting component 274 to prevent the rotational cutting component 274 from disconnecting from the drive shaft 46. The hub portion 221 defines an offset 217 between the shutter clamping surface 221a and the rotational cutting component retention surface 219a. The offset 217 extends in a front-to-rear direction and provides a gap between the surfaces 221a, 219a in which an inner portion 290i of the shutter 290 is received. The gap provided by the offset 217 is larger than then thickness of the inner portion 290i and prevents the inner portion 290i from being clamped by the retaining cap 225 when the fastener 227 is tightened. In this way, the retention assembly 223 does not interfere with the ability of the rotational cutting component 274 to rotate relative to the shutter 290 about an axis of rotation 275.

The cutting unit 234 also includes slide pins 294 (e.g., dowel pins) having front ends inserted within openings defined by the back side 283 of the rotational cutting component 274 (see FIG. 15). Rear ends of the slide pins 294 fit within corresponding arcuate slots 293 defined by the shutter 290. The arcuate slots 293 have curvatures defined by radiuses swung about a centerline that extends along the axis of rotation 275. The slide pins 294 serve two primary functions. First, the slide pins 294 allow torque to be transferred from the shutter 290 to the rotational cutting component 274 when torque is applied to the shutter 290 by the drive stem 46 of the drill head 30. Thus, during drilling, torque for rotating the rotational cutting component 274 about the axis of rotation 275 is provided by the drive stem 46 and is transferred from the shutter 290 to the rotational cutting component 274 through the slide pins 294. The rotational cutting component 274 and the shutter 290 are rotated in unison about the axis of rotation 275 by the drive shaft 46 during drilling operations. The slide pins 294 and the slots 293 also allow the shutter 290 and the rotational cutting component 274 to be rotated relative to one another about the axis of rotation 275. In this way, similar to the first embodiment described herein, the rotational cutting component 274 and the shutter 290 can be moved to a first relative rotational position in which through-holes 291 of the shutter 290 align with the through-holes 288 of the rotational cutting component 274 such that the through-holes 288 are open to allow material to pass in a front-to-back direction through the cutting unit 234. The slide pins 294 and the slots 293 also allow the rotational cutting component 274 and the shutter 290 to be moved to a second relative rotational position in which the shutter 290 blocks the through-holes 288 by preventing material from passing through the cutting unit 234 in a front-to-back action.

The cutting unit 234 further includes a bearing member 211 that mounts between the rotational cutting component 274 and the shutter 290. The bearing member 211 includes a radial bearing portion 211a that fits over the hub 235 of the shutter 290 and provides a radial bearing between a outwardly radially facing surface of the shutter hub 235 and an inwardly radially facing surface of the rotational cutting component 274. The bearing member 211 also includes an axial/thrust bearing structure 211b that forms a bearing between a front side of the shutter 290 and the back side 283 of the rotational cutting component 274.

The cutting unit 234 is shown including a nut 213 for securing the retention assembly 223 to the rotational cutting component 274 and the shutter 290 during storage and shipping. It will be appreciated that the nut 213 is removed and discarded when the cutting unit 234 is mounted to the drill head 30.

In the embodiment of FIGS. 13-15, drilling ideally takes place when the cutting unit 234 is rotated in a rotational direction 297 about the axis of rotation 275. Rotation of the shutter 290 by the drive shaft 46 in the rotational direction 297 causes the slide pins 294 to slide within the slots 293 to ends 298 of the slots 293. With the slide pins 294 located at the ends 298 of the slots 293, the shutter 290 and the rotational cutting component 274 are in the open position in which fluid communication is provided between the front and back sides of the cutting unit 234. As the shutter 290 continues to be rotated in the rotational direction 297 while the slide pins 294 are located at the ends 298 of the slots 293, torque is transferred from the shutter 290 to the rotational cutting component 274 by the slide pins 294. In this way, the rotational cutting component 274 rotates in unison with the shutter 290 such that the through-holes 288 remain open.

When drilling operations stop, it may be desirable to close fluid communication between the front and the back sides of the cutting unit 234. To accomplish this, the shutter 290 is rotated by the drive shaft 46 in a rotational direction 295 about the axis of rotation 275. As this occurs, the slots 293 and the slide pins 294 allow the shutter 290 to rotate relative to the rotational cutting component 274 from the open position to the closed position. In the closed position, the slide pins 294 engage ends 296 of the slots 293 and blocking portions of the shutter 290 cover the through-holes 288 of the rotational cutting component 274. To re-open the through-holes 288, the shutter 290 is merely rotated in the direction 297 about the axis of rotation 175, causing the shutter 290 to move relative to the rotational cutting component 274 back to the open position. One advantage of this version of the cutting unit is that contact between the cutting teeth of the rotational cutting component 274 and the ground provides resistance that prevents the shutter 290 and the rotational cutting component 274 from rotating in unison with one another when it is intended or desired to close the through-holes by rotating the shutter 290 in the direction 295 relative to the rotational cutting component 274.

From the foregoing detailed description, it will be evident that modifications and variations can be made in the devices of the disclosure without departing from the spirit or scope of the invention.

DRILLING APPARATUS WITH SHUTTER

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