Patent Application
20160097276
The present disclosure relates generally to a continuous mining machine, and more particularly, to a continuous mining machine having a core cutting assembly.
A drum continuous miner (CM) is a machine used for underground mining of ore seams. A typical CM includes a frame propelled by tracked drive units. The frame supports a power source (e.g., an electric motor) and a milling drum. The milling drum, fitted with cutting tools, is rotated through a suitable interface by the power source to break up an exposed surface of the ore seam. The broken up material is deposited by the milling drum onto a conveyor for removal from an underside of the CM to a rear end of the CM. The material is then transferred from the conveyor into a nearby haul vehicle for transportation away from the worksite.
The milling drum is generally supported at spaced apart locations by vertically oriented struts. In particular, the milling drum can be divided into three or five different segments, with a strut located between adjacent segments. The struts vertically support the milling drum, and also provide a way to drive the milling drum. For example, a shaft, a belt, or a chain can pass from the electric motor through the strut to the milling drum, thereby engaging an end of each drum segment to rotate the drum. Because the cutting surface of the milling drum is segmented at the struts, a vertical core of unmilled material may be left at each strut location. These cores, if left intact, can inhibit further penetration of the CM into the ore material. Accordingly, the cores must be periodically broken off and moved out of the way of the struts.
An exemplary continuous mining machine is disclosed in U.S. Pat. No. 8,511,757 of O'Neill that issued on Aug. 20, 2013 (“the '757 patent”). Specifically, the '757 patent discloses a mining machine having a core breaker. The core breaker is positioned between the cutting drums of the mining machine, and includes a circular beveled blade having a plurality of bits that can break the core material into fragments. The beveled blade is forced into the core material by forward motion of the mining machine. By breaking the core material into fragments, the barrier to further penetration of the milling drum into the ore seam is eliminated.
Although the core breaker of the '757 patent may be beneficial in removing the vertical core left between adjacent segments of a milling drum, the core breaker may be less than optimal. In particular, a force necessary to push the core breaker into the material core may be significant, requiring the mining machine to be large and heavy and to have an engine or motor with significant power, A large, heavy mining machine may be inefficient, and the size of the engine or motor required to move the machine may have poor efficiency and be expensive to purchase and to operate.
The disclosed mining machine and core cutting assembly may be directed at overcoming one or more of the problems set forth above and/or other problems in the prior art.
One aspect of the present disclosure is directed to a core cutting assembly for a continuous mining machine having a milling drum. The core cutting assembly may include a drive mechanism configured to rotate about a first axis of the milling drum. The core cutting assembly may also include at least one rotary cutting bit powered by the drive mechanism to rotate about a second axis that is substantially orthogonal to the first axis.
Another aspect of the present disclosure is directed to a milling system for a continuous mining machine. The milling system may include a milling drum, a plurality of cutting tools mounted to an outer cylindrical surface of the milling drum, and a strut supporting the milling drum, The milling system may also include a shaft connected to rotate the milling drum about a first axis, and a drive mechanism connected to the shaft at an end of the milling drum. The milling system may further include at least one rotary cutting bit supported by the strut and powered by the drive mechanism to rotate about a second axis that is substantially orthogonal to the first axis.
Yet another aspect of the present disclosure is direct to a continuous mining machine. The continuous mining machine may include a frame, a mobile undercarriage supporting the frame, and a boom pivotally connected to the frame. The continuous mining machine may further include a milling drum having an outer cylindrical surface divided into a plurality of segments, and a plurality of cutting tools mounted to each of the plurality of segments. The continuous mining machine may also include a strut connecting the milling drum to a distal end of the boom, a shaft configured to drive the milling drum about a first axis, and a drive mechanism mounted to the strut and driven by the shaft to rotate about the first axis of the milling drum. The continuous mining machine may additionally include a plurality of rotary cutting bits arranged within a common plane, supported by the strut in a forward driving direction of the mining machine, and powered by the drive mechanism to rotate about a second axis that is substantially orthogonal to the first axis.
Milling system 12 may be configured to engage and fragment the ore seam at a location forward of and above CM 10. In particular, milling system 12 may include, among other things, a milling drum 20 that is rotatably connected to frame 16 by way of a boom 22. Boom 22 may be configured to selectively raise and lower milling drum 20 along an arcuate trajectory 24, allowing milling drum 20 to engage a front wall and/or a ceiling of a mining tunnel in which CM 10 is operating.
Milling drum 20 may be divided into multiple drum segments, each segment having an outer surface 26 to which a plurality of cutting tools 28 are attached. In the disclosed embodiment, milling drum 20 is shown as being divided into three segments, including a center segment 30, and left- and right-side segments 32, 34, respectively. It is contemplated that milling drum 20 may be divided into any number of segments, or not divided at all.
Milling drum 20 may be connected to boom 22 by way of one or more struts 36. In the disclosed embodiment having three drum segments, one strut 36 is shown as being located between each pairing of adjacent segments. That is, milling drum 20 shown in
In some embodiments, a connection between the power source of CM 10 and milling drum 20 may pass through one or more of struts 36. For example, one or more of struts 36 may be hollow or recessed, and the corresponding connection (e.g., a shaft connection, a belt connection, a chain connection, etc.) may be located within (e.g., pass through) the hollow or recessed portion of strut 36 to connect with milling drum 20. This connection may result in rotation of milling drum 20 about a longitudinal axis 38. It may be possible for the power connection to be located away from strut 36 in some applications.
Cutting tools 28 may be angled relative to a circumferential direction of milling drum 20. For example, cutting tools 28 may be skewed toward ends of the corresponding drum segments. In this configuration, tips of the cutting tools 28 located closest (e.g., immediately adjacent) to struts 36 may axially overhang struts 36 a distance. This overhang may reduce a width of a material core located at struts 36 that is not fragmented by cutting tools 28.
Milling system 12 may additionally include a core cutting assembly 40 configured to fragment the material core not removed by cutting tools 28 at each strut location. An exemplary core cutting assembly 40 is shown in
Drive mechanism 42 may be connected to the power source of CM 10 by way of a shaft 48. For example, shaft 48 could include a pinion gear 50 that intermeshes with the ring gear of drive mechanism 42. In one embodiment, shaft 48 is the same shaft that also drives the rotation of milling drum 20, and the ring gear of drive mechanism 42 may be concentric with milling drum 20 to rotate about the same longitudinal axis 38. In another embodiment, shaft 48 may be separate from the shaft that drives the rotation of milling drum 20.
Rotary cutting bits 44 may be oriented to each rotate about a personal axis 52 that passes through and is substantially orthogonal (e.g., orthogonal within about +/−5°) to longitudinal axis 38. In the depicted example, three rotary cutting bits 44 are shown as all being generally aligned in the same plane. That is, the axis 52 of each rotary cutting bit 44 may generally lie in the same plane (see
As also shown in
In addition, each rotary cutting bit 44 may have a diameter about equal to or larger than a width w (shown in
Because the core of material normally left behind at struts 36 may be completely removed with the disclosed core cutting assembly 40, a width of struts 36 may no longer be limited by an ability of CM 10 to break away the core. Accordingly, struts 36 may increase in width, providing additional strength and stability to milling system 12. In addition, the increased width of struts 36 may allow for alternative drive arrangements that have improved durability and/or efficiency. Such an alternative drive arrangement is depicted in
The disclosed core cutting assembly may be applicable to any continuous mining machine having a milling drum that normally would leave behind a material core at one or more strut locations. The disclosed core cutting assembly may be positioned at these strut locations and used to fragment the material core. The core cutting assembly may fragment the material at the same radial distance and time as the milling drum, such that no core is formed. This may allow for the continuous mining machine to move forward substantially unimpeded.
Because the disclosed core cutting assembly may not allow for formation of a material core, the associated continuous mining machine may not be required to periodically break away the core in order to continue progressing forward. This may reduce a load on the continuous mining machine, allowing for increased production and efficiency. The reduced load could allow for a reduced power source size and a lighter-weight frame, thereby reducing a cost of the machine.
It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed continuous mining machine and core cutting assembly. Other embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the disclosed machine and assembly. It is intended that the specification and examples be considered as exemplary only, with a true scope being indicated by the following claims and their equivalents.
