Patent Application
20100139986
The present invention relates to the earth drilling or roof bolting arts and, more particularly, to apparatus and methods for assisting in preventing the accumulation of debris in a flow path associated with a drilling unit.
Most earth drilling systems employ some form of rotary or percussion powered drills. Typically, a drilling machine, such as for forming a hole for an explosive charge, or for anchoring a roof bolt, includes a drill socket for receiving a stem with a drill bit on the distal down hole section thereof. The stem/bit on a rotary drill machine is rotated by a shaft, sometimes called a spinner, mounted on a drill head to form the drill hole. The rotary driving motion of the spinner is usually hydraulically or pneumatically driven.
To increase the efficiency of drilling, cuttings and dust are often collected and removed from adjacent the drill bit. The removal of the cuttings and dust from adjacent the drill bit reduces airborne contamination, provides clean cutting edges at the bottom of the hole, and allows the most efficient contact with the rock, or other strata. Typically, a pneumatic or hydraulic cuttings/dust collection/suppression and removal system is employed. In one example, pressurized air, or a suitable hydraulic fluid such as water, or an air/water mixture, is forced into the borehole to bail or pick up the cuttings and dust for disposal. In one particular embodiment, this goal is achieved by applying a vacuum on a center passage of the drill steel to draw bailing fluid into the borehole around the periphery of the drill steel, whereupon the cuttings and the dust particles are entrained and removed through the center passage. In either system, this withdrawn debris is initially pneumatically or hydraulically conveyed away from the drill hole. A typical drilling arrangement and cuttings/dust collecting system is shown in the prior art; Howeth, U.S. Pat. No. 4,434,861, and Wilson, U.S. Pat. Nos. 6,637,522 and 6,216,800, the disclosures of which are incorporated herein by reference.
When using air, the cuttings and dust are then filtered out at a remote location and disposed of. In systems where water is used, either exclusively or in a mixture with other fluids, an option is to simply allow the dust to be suppressed and then deposited outside the drill hole.
Regardless of which system is employed, debris may accumulate in the center passage and areas surrounding the center passage, during the removal of the cuttings and dust. The debris tends to form a cake-like substance, especially when it is wet and especially when the flow path is not completely linear. This accumulation of debris inhibits flow and prevents the effective conveyance of the cuttings and dust away from the borehole. When this occurs, the drill bit becomes isolated from the distal cutting face of the hole by the debris, and effective drilling cannot continue. In addition, the cuttings and dust begin to create airborne contamination. Thus, drilling is often interrupted to remove the debris, resulting in drilling delays, inefficiencies, and expenses.
Accordingly, a need is identified for a manner in which to assist in preventing the accumulation of debris in a flow path during a drilling operation, such as when forming a borehole in a face of a mine passage in association with a roof bolting operation.
One aspect of this disclosure relates to an apparatus for assisting in preventing the accumulation of debris in a flow path during the formation of a borehole in a face of a mine passage using a drill bit. The apparatus comprises a drill head including a housing at least partially defining the flow path and further including a drive shaft for driving the drill bit to form the borehole. The apparatus further comprises at least one agitator positioned in the housing for agitating debris in the flow path.
Preferably, the at least one agitator extends transverse to a flow direction of a portion of the flow path associated with the drive shaft. However, the at least one agitator should be positioned so as not to obstruct the flow of dust and debris along the path. The at least one agitator may comprise an elongated rod or blade and, most preferably, comprises two agitators, which alone or together may be supported by a carrier connected to the drive shaft.
Another aspect is a drilling or bolting unit for use with a drilling element for forming a borehole in a face of a mine passage. The drilling unit comprises a drill head having a rotatable drive shaft for driving the drill bit to form the borehole. A carrier connected to the drive shaft connects to at least one agitator for agitating debris in the flow path.
The carrier may further include an opening forming a portion of the flow path, in which case the at least one agitator does not extend across the opening. The unit may further include a dust chamber within the housing. with the at least one agitator projecting into the dust chamber.
A further aspect of the disclosure is an apparatus for assisting in preventing the accumulation of debris in a flow path during the formation of a borehole in a face of a mine passage. The apparatus comprises a drill head including a drive shaft for driving the drill bit to form the borehole. The drill bit includes a passage forming a flow path for debris from the borehole. At least one agitator is associated with the drive shaft for agitating debris in the flow path.
Preferably, the drive shaft comprises a rotatable drive shaft including a passage in fluid communication with the passage of the drill bit. The apparatus may further include a carrier connected to the drive shaft for carrying the at least one agitator. The carrier in turn includes an opening in fluid communication with the passage of the drive shaft. Preferably, the agitator is mounted for movement with the drive shaft and, most preferably, comprises a pair of agitators.
Yet a further aspect of the invention is a method of manufacturing a drill head for assisting in preventing the accumulation of debris in a flow path during the formation of a borehole in a face of a mine passage using a drill bit actuated by a drive shaft. The method comprises connecting at least one agitator to the drive shaft for agitating debris in the flow path.
Reference is now made to
As illustrated in
To form the borehole, a drilling element 17, such as a drill steel including a “bit” may be received at the distal, down hole point of a socket 19 associated with the drive shaft 18. This socket 19 via the passage through the drill steel thus forms the inlet to the flow path 15 in the housing 11 for receiving the debris generated during drilling in this most preferred embodiment. In addition, the flow path 15 may be connected via an outlet 11a in the housing 11 to a pressure source 16, such as a vacuum. As should be appreciated, this will create a flow through the flow path 15 for receiving and then delivering the debris generated during the advance of the drill bit to form the borehole to a downstream location for collection and eventual disposal.
In accordance with one aspect of the disclosure, an apparatus 20 for assisting in preventing the accumulation of debris in the flow path 15 is provided. In the preferred and illustrated embodiment, this apparatus includes a carrier and at least one agitator 22a connected thereto. The carrier may take the form of any device capable of carrying the agitator 22a, such as a rotating mechanical face seal carrier 21, preferably positioned adjacent to the outlet 11a of the housing 11. The agitator 22a may take the form of any device capable of agitating debris but most preferably comprises an elongated blade or elongated rod (and, most preferably, comprises an L-shaped structure).
The carrier 21 may be connected to the rotatable shaft 18 used to induce rotation in the bit as the result of the power input. In the preferred embodiment, the mounting of the carrier 21 is such that it at least partially occupies an adjacent dust chamber 13, through which debris flows in moving along the flow path 15 and may accumulate in the course of the drilling operation. Preferably, the agitator 22a is arranged relative to the carrier 21 to project into the dust chamber 13 in a direction transverse to the direction of the flow 14 in the flow path 15. Also, the carrier 21 may be associated with a mechanical face seal 29 on the drilling unit 10, which is used to forestall dust and the like from infiltrating the bearings and gears associated therewith.
A more detailed perspective view illustrating one embodiment of the apparatus 20, for assisting in preventing the accumulation of debris in the flow path, is shown in
Returning to
Of course, the formation of the borehole creates dust, cuttings, and other debris. Thus, the pressure source 16 creates the flow through the flow path 15 to bail or pick up the cuttings, dust, and other debris for disposal and to convey the debris away from the borehole. As the debris is conveyed through the flow path 15 and away from the borehole, the carrier 21, which is directly coupled to the shaft 18 in the preferred embodiment, moves relative to the housing 11 in a simultaneous fashion. Consequently, the agitators 22a, 22b (shown in
Specifically, the agitators 22a, 22b extend transverse to the direction of the flow 14 in the flow path 15 and project into the dust chamber 13, defined by the carrier 21. During actuation of the drive shaft 18 to which the carrier 21 is bodily connected, the agitators 22a, 22b thus move at a correspondingly high rate of speed about the axis of rotation (or along it in the case of a non-rotational movement). In any case, this movement serves to create a shredding or swirling action in order to disrupt and agitate any debris in the dust chamber 13 (and, more specifically, in the gap between the outlet end of the opening 23 and the inlet end of the opening 11a). At the same time, the agitators 22a, 22b do not extend across the opening of the carrier 21 or into the flow path 15 (including the adjacent outlet 11a of the housing 11), In this manner, the agitators 22a, 22b do not serve as obstacles to obstruct the flow in a manner that would promote the accumulation of debris in the flow path 15. Indeed, the relatively slender, elongated nature of the agitators 22a, 22b in the preferred embodiment means that they occupy a minimal amount of space in the dust chamber 13 to avoid collecting dust or debris, but this of course does not detract from the ability to prevent accumulation in the desired manner given their positioning and relatively rapid movement.
Summarizing, the apparatus of the present invention assists in preventing the accumulation of debris in the flow path 15. Because debris does not accumulate and form a cake-like substance in the flow path 15, it remains clear and unclogged. Thus, the flow may continue through the flow path 15 during drilling, and debris may be effectively conveyed away from the borehole. Further, airborne contamination created by debris from drilling is further reduced, and the drill bit may make efficient contact with the clean cutting edges of the distal cutting face of the borehole during drilling. Accordingly, drilling may continue without interruptions to remove accumulated debris from the drilling unit 10, increasing drilling efficiency and decreasing drilling delays and expenses.
The foregoing descriptions of various embodiments of the invention are provided for purposes of illustration, and are not intended to be exhaustive or limiting. Modifications or variations are also possible in light of the above teachings. For instance, one or more of the agitators 22a, 22b could be used to manufacture a drill head or retrofit an existing drill head, such as by operatively connecting with the drive shaft. Although the outlet 11 a is shown as being positioned along one lateral side of the housing 11, such that an elbow or bend in the flow path results, the flow path 15 could be linear as well. The embodiments described above were chosen to provide the best application to thereby enable one of ordinary skill in the art to utilize the disclosed inventions in various embodiments with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the invention.
This application claims the benefit of U.S. Provisional Patent Application Ser. No. 61/121,239, the disclosure of which is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 61121239 | Dec 2008 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/US09/50521 | Jul 2009 | US |
| Child | 12503205 | US |
