The present invention relates to drive arrangements for continuous face underground mining. In particular, the invention relates to sprocket drives for an armoured face conveyor (AFC) rack system used with longwall shearers.
Traditional longwall shearers utilize a two-sprocket drive that moves the shearer along a mining face, and an example of such a drive is shown in U.S. Pat. No. 7,731,298. Generally, two-sprocket drive systems include a first sprocket that is driven by a drive system such as a motor. A second sprocket intermeshes with the first sprocket and further intermeshes with a rack extending along a mining face. As the driven first sprocket is rotated, the second sprocket is forced to rotate, thereby pulling the shearer along the rack. The first sprocket rotates about a first axis and the second sprocket rotates about a second axis parallel to the first axis. The second sprocket is rotatable about the first sprocket such that the vertical distance between the first axis and the second axis is adjustable. In this way, the height of the shearer may be adjusted, as desired, to accommodate various mining faces.
Traditional two-sprocket drive arrangements provide for a wide range of height adjustability. However, in low-height conditions or thin mining seams (i.e., low seams) the two-sprocket arrangement does not provide a low enough profile while also providing a desired material removal rate. Further, in a two sprocket design, wear between the top and driven sprocket can be troublesome. Since the driven sprocket must float axially with the top sprocket fixed, tooth wear can create thrust loads that can damage haulage components.
In one construction, the invention provides a mining machine for mining along a mining face. The mining machine includes a longwall shearer, a product removal system for removing product cut by the longwall shearer, and a drive system for moving the longwall shearer along a rack extending along the mining face. The drive system includes a housing coupled to the longwall shearer, a motor, and a sprocket at least partially positioned within the housing and drivingly connected to the motor. The sprocket is engaged with the rack and moves the longwall shearer along the rack. A shoe maintains the sprocket in engagement with the rack. The housing is configured to rotate relative to the longwall shearer such that the drive system adjusts for vertical height variations and horizontal variations of the rack.
In another construction, the invention provides a mining machine for mining a mining face of material. The mining machine is movable along an armoured face conveyor that includes a rack. The mining machine includes a body that defines a first side facing toward the mining face and a second side facing away from the mining face, a cutter head that is mounted to the body for cutting into the mining face, a prime mover, and a drive system that moves the mining machine along the rack. The drive system includes one-and-only-one sprocket that is driven by the prime mover and engages the rack to move the mining machine along the mining face.
In another construction, the invention provides a drive assembly for a mining machine for mining along a mining face. The mining machine defines a face-side toward the mining face and a gob-side away from the mining face and includes a longwall shearer, a product removal system for removing product cut by the longwall shearer, a rack extending along the mining face, and a prime mover positioned within the longwall shearer. The drive assembly includes one-and-only-one sprocket coupled to the prime mover by a drive shaft and driven by the prime mover to move the mining machine along the mining face. The drive assembly further includes a sprocket housing that is coupled to the longwall shearer and includes a shoe that selectively engages the rack to maintain the rack in engagement with the sprocket. The sprocket is disposed within the sprocket housing. The shoe includes a face-side member that engages a bottom surface of the rack, a spacer member, and a gob-side member that engages a gob-side of the rack. The drive shaft defines a longitudinal axis and the sprocket is movable along the longitudinal axis on the drive shaft. Further, the sprocket housing rotates relative to the longwall shearer about the longitudinal axis and in a face-to-gob direction.
Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings.
Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways.
The longwall shearer 10 is moved along a mining face by the drive system 26 to cut into the mining face. Typically, such longwall shearers 10 are used for mining coal. As the face is cut by the front cutter head 22, the material falls onto the product removal system 30, which is a conveyor in the illustrated construction, and is conveyed away from the face to shuttle cars or another removal solution (e.g., train, carts, a separate conveyor, etc.). The shearer 10 defines a direction of travel A along which the drive system 26 moves the shearer 10, a first or face-side B facing toward the mining face, and a second or gob-side C facing away from the mining face (i.e., opposite the face-side).
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In typical longwall shearers, the planetary gear set is positioned in a center of the longwall shearer body directly above the conveyor. Shifting the position of the planetary gear set 66 away from the center of the shearer body 14 allows the shearer body 14 to be lowered toward the conveyor 58 and the bottom surface 64 of the shearer body 14 to be raised. This arrangement allows the overall height of the shearer 10 to be lower while maintaining a tunnel 63 between the top surface 62 of the conveyor 58 and the bottom surface 64 of the shearer body 14 that is large enough to move the desired amount of material therethrough.
A drive sprocket assembly 90 is coupled (e.g., fastened) to a mounting surface 94 (
The bearing carrier 98 includes a carrier housing 110, a bearing 114, and a coupling ring 118 coupled to the carrier housing 110. The ring 118 includes a retaining surface 122 (
The bearing 114 includes two bearing members that couple the drive shaft 78 to the drive sprocket assembly 90 such that the drive shaft 78 rotates relative to the bearing carrier 98 and the sprocket housing 102. The annular projection 134 is positioned between the two bearing members, and the first bearing member 114A is held in place with a bearing retainer 142 (which is threaded onto the shaft 78 in the illustrated construction), while the second bearing member 114B is sandwiched between the annular projection 134 and a projection 146 formed on the drive shaft 78. In the illustrated construction, the first and second bearing members 114A, 114B are roller bearings designed to handle radial, moment, and thrust loads. In other constructions, the bearing members may be different, as desired, to provide a rotational coupling between the drive shaft 78 and the drive sprocket assembly 90. A seal carrier 150 with seal (not shown) is coupled to the drive shaft 78 (e.g., via press fit) to retain oil in the gear case and inhibit material from accessing the bearing carrier 98.
The sprocket housing 102 includes a first bushing 154 coupled to the housing support surface 138 of the carrier housing 110, a face-side member 158 in which the first bushing 154 is seated and held to the bearing carrier 98 by the coupling ring 118, a gob-side member 162, and a spacer member 166 positioned between the face-side member 158 and the gob-side member 162. With reference to
The face-side member 158 includes an aperture 178 through which the drive shaft 78 passes. A bushing recess 182 is formed into a face-side of the face-side member 158 and shaped to receive the first bushing 154 therein such that the first bushing 154 does not rotate relative to the face-side member 158. The bushing recess 182 is also formed to interact with the coupling ring 118. The bushing recess 182 is formed such that the coupling ring 118 does not engage side portions 186 (
The face-side member 158 also includes a trapping shoe portion 198, which is defined by a groove formed in a gob-side face of the member 158, for engaging the rack 34. The trapping shoe portion 198 defines a lower lip 202 that engages the bottom surface 46 of the rack 34, an upper lip 206 that engages the top surface 50 of the rack 34, and a side surface 210 that engages the face-side surface 38 of the rack 34. The lower lip 202, the upper lip 206, and the side surface 110 move in and out of contact with the rack 34; however, the lips 202, 206 and the side surface 110 maintain the rack 34 in engagement with the sprocket 106 during variations in the rack 34 path along the length of the rack 34.
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The cap recess 222 is generally circular and includes two flat portions. A cap 238 is seated in the cap recess 222 and includes a periphery that compliments the shape of the cap recess 222, a central aperture 242, and an extended sidewall 246 that axially extends into the aperture 218 of the gob-side member 162. A generally circular shaft recess 250 is formed in the cap 238 from the face-side and includes two flat portions.
A rigid bushing 254 is coupled to a gob-side end of the drive shaft 78 (e.g., via press-fit). A second bushing 258 is fit about the rigid bushing 254 and is seated within the shaft recess 250 of the cap 238. The second bushing 258 includes two flat portions that correspond to the flat portions formed in the cap recess 222. The second bushing 258 cooperates with the first bushing 154 to allow the sprocket housing 102 to pivot or rotate in the horizontal plane with respect to the bearing carrier 98. In another construction, the rigid bushing 254 is replaced with a roller bearing.
In the illustrated construction, the spacer member 166 includes two spacer plates, each of the plates sandwiched between and coupled to the face-side member 158 and the gob-side member 162. The spacer member 166 provides enough room within the sprocket housing 102 for the sprocket 106 to operate as desired. In other constructions, the spacer member 166 may be formed as a part of the face-side member 158, the gob-side member 162, or have a different shape.
The sprocket 106 includes a splined aperture 262 that receives the first splined portion 82 of the drive shaft 78, and a plurality of teeth that engage the teeth of the rack 34. The first splined portion 82 of the drive shaft 78 is wider than the sprocket 106 and the sprocket 106 is allowed to slide axially on the splined portion 82 to further adjust for horizontal variations in the path of the rack 34 and rack/sprocket wear. As the drive shaft 78 rotates, the sprocket 106 is rotated and pulls the longwall shearer 10 along the rack 34 to continuously cut the mining face with the cutter head 22.
The illustrated sprocket housing 102 rotates (i.e., pivots, articulates) about the longitudinal axis of the drive shaft 78 in order to accommodate or adapt to peaks and valleys (i.e., vertical height variations) of the rack 34 along the mining face. This arrangement allows the trapping features (e.g., the trapping shoe portion 198 of the face-side member 158 and the shoe portion 214 of the gob-side member 162) to be integrated into the sprocket housing 102. The sprocket housing 102 also adapts to the rack 34 snaking by articulating horizontally (i.e., in the face-to-gob plane). Such articulation reduces wear of the trapping features and the rack 34.
The uni-sprocket drive assembly 90 offers a mining machine that lowers cost per ton of mined product in mines with a low seam height and reduces the amount of rock cut by the mining machine leading to less reject material cut from the face. The shearer 10 can mine at a height of about 1.3 meters, which is not possible with current longwall methods, shearers or plows. The longwall shearer machine 10 can cut as low as 1.3 meters and still achieve 10,000 tons per day production. In order to fit the support structure (i.e., armoured face conveyor) and shearer into such a low profile envelope, some constraints are set for the illustrated construction. A minimum of 300 mm tunnel 63 height was specified in order for the required passage of material under the machine to reach the target production. The shearer body 14 height from the ground should not exceed 900 mm in order to provide ample clearance between the top of the shearer body 14 and the underside of a roof support canopy. With this constraint and as discussed above, a typical shearer two-sprocket downdrive is an obstacle in getting the desired low profile.
Shifting the planetary gear set 66 to the face-side B of the shearer body 14 makes it possible to drop the planetary gear set 66/drive shaft 78/drive sprocket 106 combination lower with respect to the shearer body 14 in order to achieve a sprocket diameter below the 900 mm machine height constraint while positioning the sprocket 106 closer to the rack 34 to create more tunnel 63 height. In order to achieve the required tunnel 63 height, the height of the rack 34 must also be raised. Typically, rack 34 heights are lowered in order to achieve the lowest possible longwall shearer body 14 profile with a conventional, two-sprocket design. In the uni-sprocket drive assembly 90 it is desirable for the rack 34 height to be raised enough to meet the pitch diameter of the drive sprocket 106 on the shearer to achieve the 300 mm minimum tunnel 63 height.
In addition, the uni-sprocket drive assembly 90 eliminates the wear that typically exists between the two drive sprockets on a two-sprocket downdrive system. Further, the ability of the inventive system to accommodate snaking and other misalignment of the rack 34 reduces the wear on the sprocket 106.
The bearing carrier 98 transfers shaft forces into the shearer body 14. Additionally, the bolt-on arrangement (a) provides the ability to remove the uni-sprocket drive assembly 90 so that a conventional, two-sprocket downdrive arrangement can be used in its place in order to raise the machine 10, (b) allows the sprocket housing 102 (with integrated trapping shoe) to rotate about the drive shaft 78 axis to handle mining face undulations, and (c) provides the means in which the housing 102 can articulate in the face-to-gob plane to minimize wear between the trapping features and the rack 34. Further, the bolt-on design allows for easy assembly, disassembly, replacement, and maintenance.
In addition, other advantages are provided and various aspects and details of the invention provide these and other advantages. One skilled in the art will appreciate that variations of the above described features exist and may be implemented to achieve the desired advantages in other ways while still embodying the spirit of the invention.
Various features and advantages of the invention are set forth in the following claims.
This application claims priority to U.S. Provisional Application No. 61/408,281, filed on Oct. 29, 2010, the entire contents of which are incorporated herein by reference in their entirety.
Number | Date | Country | |
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61408281 | Oct 2010 | US |