Patent Grant
7284624
This invention relates to gripping devices. Specifically, this invention relates to devices for gripping drill rods for use in ground drilling.
Devices such as directional drills are used in industry to bore openings underground for pipes, cables, etc. Directional drills typically use a number of sections to form a drill stem. The sections are inserted one at a time during a forward drilling operation, and are removed one at a time after the bore has reached a desired depth in order to remove the drill stem from the bore. Although an example of a directional drill is used in the following descriptions, other ground drills utilizing a number of sections of drill stem are also contemplated to be within the scope of the invention.
Sections of drill stem are typically joined together using a mating threaded joint. In this configuration, several sections of drill stem can be housed in a small space, for example in a hopper on a drill device. Drilling devices such as a directional drill are configured with gripping devices to selectively hold the sections of drill stem during a joining or detaching operation to add or remove sections of the drill stem.
A problem with current gripping device designs is that they are large and cumbersome. Existing configurations use a pair of hydraulic cylinders for a single drill gripping device, which is expensive to manufacture, and adds size and weight to a cumbersome drilling device. Further, existing drill gripping devices do not center well on a section of drill stem during a gripping operation. A poorly centered gripping device leads to excessive wear of gripping jaws, among other problems.
What is needed is a drill gripping device that is smaller and less expensive to manufacture. What is also needed is a drill gripping device with improved operation characteristics such as extended jaw life.
The above mentioned concerns including, but not limited to, manufacturing considerations, size, and extending jaw life are addressed by the present invention and will be understood by reading and studying the following specification.
A drill gripping device is shown. In one embodiment, the drill gripping device includes a pair of gripping jaws, and a single actuating device coupled to the pair of gripping jaws. In one embodiment, the drill gripping device further includes a force amplifying linkage coupled between the single actuating device and the a pair of gripping jaws. In one embodiment, the drill gripping device further includes a connecting portion, wherein the pair of jaws are connected to move together.
These and other embodiments, aspects, advantages, and features of the present invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art by reference to the following description of the invention and referenced drawings or by practice of the invention. The aspects, advantages, and features of the invention are realized and attained by means of the instrumentalities, procedures, and combinations particularly pointed out in the appended claims.
In the following detailed description, reference is made to the accompanying drawings which form a part hereof, and in which is shown, by way of illustration, specific embodiments in which the invention may be practiced. In the drawings, like numerals describe substantially similar components throughout the several views. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention. Other embodiments may be utilized and structural, or logical changes, etc. may be made without departing from the scope of the present invention.
A drilling drive block 110 is shown on the directional drill 100. The drilling drive block 110 is used to rotate a drill stem and to advance the drill stem during a drilling operation. Advancement of a drill stem is typically linear. In the example of a directional drill 100, the advancement of the drill stem is also typically at an angle of incidence to the ground as shown in
In one embodiment, the coupling portion 214 is formed from a hardened steel material to resist gripping or clamping damage. In one embodiment, the length portion is formed from a different material than the coupling portion 214. In one embodiment, the length portion is formed from a less expensive material than the coupling portion 214. In one embodiment, the length portion is formed from a mild steel material. Because the length portion is typically not used as a gripping or clamping surface, a softer steel can be used for advantages such as reduced cost in the drill stem sections.
In
A second rocker arm 322, is coupled to a second camming linkage 324. The second camming linkage 324 is coupled in turn to a second jaw carrier 326 that is adapted for holding a second gripping jaw 328. In one embodiment, the first rocker arm 314 is coupled to the second rocker arm 322 through a connecting portion 330. The connecting portion acts to synchronize motion of the first and second jaw carriers 318 and 326, and consequently the first and second gripping jaws 320 and 328.
The second gripping portion 340 includes a second actuator 342 that is coupled to a third rocker arm 344, that is coupled to a third camming linkage 346. The third camming linkage 346 is coupled in turn to a third jaw carrier 348 that is adapted for holding a third gripping jaw 350. Although one embodiment includes a gripping jaw that is separate and detachable from a jaw carrier, other embodiments may include an integrally formed jaw carrier and gripping jaw.
A fourth rocker arm 352, is coupled to a fourth camming linkage 354. The fourth camming linkage 354 is coupled in turn to a fourth jaw carrier 356 that is adapted for holding a fourth gripping jaw 358. In one embodiment, the third rocker arm 344 is coupled to the fourth rocker arm 352 through a connecting portion 360. The connecting portion acts to synchronize motion of the third and fourth jaw carriers 348 and 356, and consequently the third and fourth gripping jaws 350 and 358.
In one embodiment components of the second gripping device 340 are coupled together or related to one another by a second frame 341. Similarly, in one embodiment components of the first gripping device 310 are coupled together or related to one another by a first frame 311. In one embodiment, a third actuator 332 is coupled between the base 302 and the first frame 311 of the first gripping portion 310. The third actuator 322 drives rotational motion of the first gripping device 310 relative to the base 302, resulting in relative rotational motion of the first gripping device 310 relative to the second gripping device 340 when the third actuator 332 is actuated.
In one embodiment, actuators such as the first actuator 312, the second actuator 342 and the third actuator 332 include hydraulic cylinders. Although hydraulic cylinders are shown, other embodiments include, but are not limited to, actuators such as electric motors, pneumatic devices, solenoids, etc.
Embodiments of drill gripping devices as described above are useful for gripping a first coupling portion of a section of a drill stem, concurrently gripping a second coupling portion of a section of drill stem, and twisting one coupling portion of a section of a drill stem relative to the other coupling portion. The twisting motion is used to “break” the threaded joint allowing the two sections of drill stem to then be disassembled using conventional unscrewing methods.
The configurations of drill gripping devices described above have a number of advantages. Each gripping portion is designed with a single actuator. This configuration is less expensive to manufacture than prior configurations, and it is also smaller and more compact than prior configurations. Further, through the use of force amplifying devices, including but not limited to camming arms, a smaller actuator is possible. Again, this configuration is less expensive to manufacture, and is smaller and more compact due to the ability to use a smaller, less powerful actuator. Another advantage of the configurations of drill gripping devices described above is that the gripping jaws are actuated with more precision than prior designs.
Designs that used a separate actuator for each gripping jaw have a condition where the jaws do not always center correctly on a section of drill stem. In multiple actuator designs, the individual actuators are designed with a long travel stroke in order to compensate for possible misalignment with the drill stem. This imprecise design leads to two problems that are addressed by embodiments of the present invention. Misalignment of gripping jaws in prior designs led to premature gripping jaw wear. Further, in prior designs, due to the longer actuator stroke it was possible to damage the softer length portions of drill stem as described in
In contrast, embodiments of the present invention as described above, have improved precision and centering capabilities. One feature that facilitates the improved precision of embodiments of the invention includes the connecting portions 330 and 360. The connecting portions synchronize a pair of rocker arms, which in turn synchronize a pair of gripping jaws in a respective gripping portion such as the first gripping portion 310 or the second gripping portion 340.
Improved centering further allows the travel strokes of gripping jaws in embodiments of described above to be more limited. Limited travel strokes of the gripping jaws allows design of drill gripping devices where damage to the softer length portions of sections of drill stem is eliminated. The gripping jaws grip precisely on larger diameter, hardened steel connecting portions, but are not allowed to travel far enough to damage the smaller diameter length portions.
Embodiments of drill gripping devices described above have advantages such as an inexpensive and compact design. In one embodiment, an inexpensive and more compact design is possible through the use of a single actuator with a single gripping portion of a drill gripping device. Embodiments of drill gripping devices described above are further reduced in price and size due to a force amplification device such as a camming arm. Alternatively, an increased gripping force is possible using an existing size actuator.
Embodiments of drill gripping devices described above also include advantages such as increased precision in gripping. Features such as a connecting portion coupled between gripping jaws synchronizes gripping jaw motion to improve jaw centering capabilities. Improved jaw centering and/or increased gripping force allows the gripping jaws to get a better “bite” on connecting portions and reduces jaw slippage. Reduced jaw slippage in turn reduces jaw wear.
Further, increased precision in gripping permits designs of drill gripping devices that do not damage softer, smaller diameter length section of drill stem sections.
While a number of advantages of embodiments of the invention are described, the above lists are not intended to be exhaustive. Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that any arrangement which is calculated to achieve the same purpose may be substituted for the specific embodiment shown. This application is intended to cover any adaptations or variations of the present invention. It is to be understood that the above description is intended to be illustrative, and not restrictive. Combinations of the above embodiments, and other embodiments will be apparent to those of skill in the art upon reviewing the above description. The scope of the invention includes any other applications in which the above structures and fabrication methods are used. The scope of the invention should be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.
This application claims priority to U.S. Provisional Application No. 60/439,936 filed on Jan. 14, 2003.
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