Patent Application
20160319614
The present invention relates generally to mining equipment and, in particular, to jumbo drilling (i.e. production drilling) and rock bolting, i.e. rock drilling for installing rock bolts as ground support in an underground mine.
In a mine, ground support, e.g. rock bolts and screening, is used to prevent rock falls. Several different types of rock bolts may be used but all require that holes be drilled in the rock first. This is done with equipment known as rock drills or combined drilling-bolting systems. These are typically mobile units with a bolting head attached. To drill a hole in the rock to install ground support, the bolting head is placed against the rock face (which is called “stinging the face”) and then a hole is drilled into the rock. The unit is then indexed to install the rock bolt as ground support.
Conventionally, rock drilling systems employ centralizer assemblies composed of many rigid metal components, which are prone to vibration and which increase the weight of the assembly. These include rigid metal stinger bases, centralizer bases and tops, steel centralizer bushings. The metal components transmit unwanted vibrations from the drill steel to the feed assembly, causing wear and loosening of components.
In view of these shortcomings of the prior art, an improved rock drilling system remains highly desirable.
In broad terms, the novel rock drilling system includes one or more elastomeric centralizer bases that minimize vibration and weight.
Accordingly, one inventive aspect of the present disclosure is a rock drilling system comprising a rock drill adapted to hold a drill steel to which a drill bit is connected, a drill feed rail for slidably supporting a drill feed that displaces the rock drill along the drill feed rail, a stinger-supported centralizer assembly for centralizing the drill steel, wherein the stinger-supported centralizer assembly has a centralizer base made of an elastomeric material, and a travelling cradle centralizer assembly slidable over the drill feed rail for centralizing the drill steel, wherein the travelling cradle centralizer assembly has a cradle made of an elastomeric material.
Another inventive aspect of the present disclosure is a stinger-mounted centralizer assembly comprising a centralizer base made of an elastomeric material, the base having a lower portion that includes a bore dimensioned to receive a hydraulically extendable stinger rod to which a stinger pad is mounted, wherein the base also has an upper portion that includes a bushing support defining a round trough and a bushing fastened to the bushing support, wherein the bushing is dimensioned to receive a drill steel.
Yet another inventive aspect of the present disclosure is a travelling cradle centralizer assembly comprising a cradle made of an elastomeric material, the cradle being slidable over a feed rail, a base mounted on the cradle, the base having an upper portion that includes a bushing support defining a round trough, and a bushing fastened to the bushing support, wherein the bushing is dimensioned to receive a drill steel.
This summary is provided to highlight certain significant inventive aspects but is not intended to be an exhaustive or limiting definition of all inventive aspects of the disclosure. Other inventive aspects may be disclosed in the detailed description and drawings.
Further features and advantages of the present invention will become apparent from the following detailed description, taken in combination with the appended drawings, in which:
It will be noted that throughout the appended drawings, like features are identified by like reference numerals. It should furthermore be noted that the drawings are not necessarily to scale.
In general, the embodiments of the present invention provide a novel rock drilling system and method. The system and method utilize elastomeric centralizer assemblies. Elastomeric assemblies reduce the amount of vibration that travels from the drill steel to the drill feed assembly, thereby reducing wear on the drill feed assembly. In one set of embodiments, an elastomeric centralizer assembly is mounted in a stationary position on the stinger to support a forward portion of the drill string. In another set of embodiments, an elastomeric travelling cradle centralizer assembly is designed to slide over a feed rail, i.e. a drill feed rail of a rock drilling system. In one particular implementation, the centralizer assemblies are made of urethane although these assemblies may be made of any other equivalent or suitable elastomeric material having similar mechanical properties.
Replacing existing rigid metallic components of a centralizer assembly with an elastomeric material attenuates the vibrations that propagate from the drill steel to the feed assembly, thereby reducing wear on the feed components. This new elastomeric design also reduces the number of parts as well as the weight of the assembly. A lighter assembly requires less motive power and thus consumes less energy.
In the embodiments depicted by way of example in
A centralizer bushing 17 is attached via fasteners 16 to the optional heat guard 13 (or is attached directly to the base 12 if no heat guard is desired). The bushing 17 remains steel (or other suitable metal or metal alloy). In a variant, the heat guard and bushing may be a single component.
In the embodiment illustrated in
In the embodiment depicted by way of example in
In the embodiments depicted by way of example in
In the embodiment shown by way of example in
In the embodiment shown by way of example in
The elastomeric centralizer assemblies, which may be made of urethane, may be manufactured using casting or moulding techniques that are known in the art.
The elastomeric centralizer base and cradle depicted by way of example in the figures are composed of an amalgamation of parts that are made of one or more vibration-attenuating elastomeric materials. In addition to vibration attenuation, the elastomeric assembly reduces the number of parts required to perform the drill-centralizing function. The use of lightweight elastomeric materials also reduces the overall weight of the assembly. The elastomeric centralizer bases furthermore eliminate the need for a rigid metallic centralizer cap by directly fastening the steel centralizer bushing to the elastomeric centralizer base. This also reduces the number of components and the weight of the assembly.
It will be appreciated that the rock drilling system could utilize the elastomeric base in only the travelling cradle or only in the stinger-mounted centralizer although best vibration-attenuation results and weight savings will be obtained when both centralizer bases are elastomeric. The concept of elastomeric bases may be applied to centralizers on the bolting feed as well as the drilling feed although it most useful on the drilling feed because of the higher vibrations encountered in drilling.
The inventive concept of an elastomeric centralizer assembly may be applied to other types of drilling equipment, drilling jumbos, or hydraulic rock drill systems. For example, a simple hydraulic percussive rock drill system disclosed in U.S. Pat. No. 3,995,700 (Mayer et al) may incorporate an elastomeric centralizer assembly in accordance with another embodiment. The rock drill system (or “drill rig”) of U.S. Pat. No. 3,995,700 is depicted in
It is to be understood that the singular forms “a”, “an” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a device” includes reference to one or more of such devices, i.e. that there is at least one device. The terms “comprising”, “having”, “including” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of examples or exemplary language (e.g., “such as”) is intended merely to better illustrate or describe embodiments of the invention and is not intended to limit the scope of the invention unless otherwise claimed.
The present invention has been described in terms of specific embodiments, examples, implementations and configurations which are intended to be exemplary or illustrative only. Other variants, modifications, refinements and applications of this innovative technology will become readily apparent to those of ordinary skill in the art who have had the benefit of reading this disclosure. Such variants, modifications, refinements and applications fall within the ambit and scope of the present invention. Accordingly, the scope of the exclusive right sought by the Applicant for the present invention is intended to be limited solely by the appended claims and their legal equivalents.
