Swivel-head Continuous Miner

Field of Invention

A substantial proportion of the world's underground coal resources are contained in inclined seams. These inclined seams occur in most major coal mining countries. Currently available continuous miners, which are capable of high rates of production, are designed to work in relatively flat seams where the roof can be cut parallel to the floor.

When mining inclined seams, it is desirable for the roof to be cut parallel to the bedding plains of the strata. However, a roadway cut by a conventional drum type continuous miner will have rectangular cross section. When cut in inclined strata the roof will feature numerous feather edges which are potentially unstable, and require a very high roof bolt density to stabilize. The shape is also not particularly adaptable to facilitating longwall extraction of strata adjacent to the roadway.

As such, many of these inclined seams resources have not been mined to date.

Background

Currently there are available essentially two types of tunnel driving machine, the drum miner and the road header. These machines are manufactured by various equipment manufacturing companies throughout the world.

The road header has a relatively small cutting element or elements mounted on a boom which protrudes in front of the machine. The machine is trammed forwards into the face, sumping in the cutting element(s) and the face is then excavated by both slewing the boom from side to side and raising and lowering the boom. The shape and size of the excavation is controlled by the extent to which the boom is raised and slewed and hence excavations of various shapes can be cut. In addition, due to the relatively small size of the cutting element(s), hard minerals can be cut. A disadvantage of this system is the low rate of production which makes the machine unsuitable for high productivity systems.

The currently available drum type continuous miners have cutting heads that vary in the range of approximately 3 metre (10 ft.) to 5 metre (18 ft.) in width. The heads can be

raised and lowered but remain parallel to the chassis of the continuous miner. This limits the drum type continuous miner to cutting essentially rectangular roadways. The relatively large width and simple up and down motion allows large power ratings to be employed, high shearing forces to be applied and consequent high rates of production.

Summary of the Invention

Embodiments of the present invention provide a cutting head mounting that enable the high rates of production of the drum type continuous miner to be employed in situations where an inclined roof is required by providing a mechanism to transversely tilt the drum. This enables the drum to cut an inclined roof with the added benefit of enabling cutting of transverse transitions in the floor grade.

In one broad form the-present invention provides a drum type continuous mining machine having:

a chassis adapted for movement upon a floor;

an adjustable mounting assembly mounted on the chassis, and

an elongate cutter drum assembly mounted on the mounting assembly and extending transversely relative to the chassis,

wherein the mounting assembly is adjustable to vary the transverse inclination of the cutter drum assembly relative to the chassis.

The mounting assembly preferably includes a sub-frame. The elongate cutter drum assembly is preferably mounted on the sub-frame. The cutter drum assembly may be mounted on the sub-ftame for rotation about an axis generally perpendicular to the transverse direction. Alternatively the cutter drum assembly may be rigidly mounted on the sub-frame and the orientation of the sub-frame is changed to vary the transverse inclination of the cutter drum assembly relative to the chassis.

The mounting assembly preferably includes adjustable members connected to the chassis, whereby at least one of the transverse and longitudinal inclinations of the mounting assembly relative to the chassis is adjustable.

The transverse inclination of the cutter drum assembly may be adjusted by rotation about a first axis generally perpendicular to the transverse direction.

Preferably this is achieved by having at least part of the mounting assembly rotating about the first axis relative to the chassis.

Preferably the mounting assembly includes first and second sub-assemblies rotatably connected together for rotation about the first axis, the cutter drum assembly connected to the first sub-assembly.

Alternatively the cutter drum assembly may be mounted substantially rigidly to the mounting assembly and the orientation of the mounting assembly relative to the chassis may be changed to vary the transverse inclination of the cutter drum assembly relative to the chassis.

The mounting assembly may include various drive means to rotate the cutter drum assembly about the axis. The drive means may include at least one length adjustable member. The at least one length adjustable member may be selected from a group including hydraulic and mechanical rams. The drive means may include at least one length adjustable member that engages the first and second sub-assemblies to affect rotation.

Preferably the or each length adjustable member engages the first sub-assembly at a respective location spaced from the first axis.

The drive means may include a ring gear.

Locking means, other than the mechanism of the drive means that adjusts the inclination of the cutter dram assembly, may also be provided to rigidly lock and unlock the cutter drum assembly at any transverse inclination or at one of a number of preset positions to prevent reaction forces from inadvertently changing the desired angle of inclination.

The mounting assembly may be mounted on the chassis for rotation about a generally transversely extending axis.

The mounting assembly may be elongate and extend generally perpendicular to the

transverse direction.

Preferably the inclination of the mounting assembly perpendicular to the transverse direction is adjustable. The mounting assembly may be mounted to the chassis via at least one length adjustable member.

The transverse inclination of the mounting assembly relative to the chassis may also be adjustable.

The mining machine preferably has a control system for controlling the transverse inclination of the cutter drum assembly. The control system preferably includes sensors for detecting or providing data indicative of at least one of: the transverse inclination of the chassis relative to the horizontal, the transverse inclination of the cutter head relative to the horizontal, the transverse inclination of the cutter head relative to the chassis, the longitudinal inclination of the chassis relative to the horizontal, the vertical position of the cutter head relative to the floor and the vertical position of the cutter head relative to the chassis.

Preferably the control'means is operable to control at least one of: the upper cutting height, the lower cutting height, the transverse inclination of the drive axis.

Preferably the control means is operable to automatically adjust the transverse inclination of the cutter drum assembly as the drum moves between the upper and lower cutting heights.

Preferably the control means is operable to automatically adjust the transverse inclination of the cutter drum assembly to compensate for changes in transverse inclination of the chassis.

Preferably the control system includes an interface, including a human interface, whereby parameters relating to at least one of: floor height, longitudinal inclination of the floor, transverse inclination of the floor, longitudinal inclination of the roof and transverse inclination of the roof of a desired cutting may be input.

In another broad form the invention also provides an adaptor for mounting a

conventional elongate drum cutter head to a sub-frame of a continuous mining machine, the adaptor having a first part adapted to attach to the sub-frame and a second part adapted to attach to the drum cutter assembly, the first and second parts connected to each other for rotation about an axis substantially perpendicular to the drive axis.

Brief Description of the Drawings

Figure 1 illustrates a rectangular opening in inclined strata, as would be cut by a conventional drum type continuous miner.

Figure 2 illustrates an opening with a roof cut parallel with the strata.

Figure 3 shows a plan view of the general arrangement of a cutting head on an adjustable mounting according to a first embodiment of the invention.

Figure 4 shows a general side end view of the mechanism for rotating the cutting head of figure 3.

Figure 5 shows a front perspective view of a continuous miner according to the first embodiment of the invention with the head raised and the cutting head parallel to the chassis.

Figure 6 shows a front perspective view of a continuous miner according to the first embodiment of the invention with the head raised and the cutting head slewed.

Figure 7 shows a side view of a second embodiment of the invention.

Figure 8 shows plan view of the general arrangement of a cutting head on an adjustable mounting according to the second embodiment of the invention

Figure 9 shows a side view of a third embodiment of the invention.

Figure 10 shows plan view of the general arrangement of a cutting head on an adjustable mounting according to the third embodiment of the invention

Figure 11 shows an end view of the third embodiment of the invention.

Detailed Description of Preferred and other Embodiments

Figure 1 illustrates a roadway 2 having a rectangular cross section in inclined strata 4, as would be cut by a conventional drum type continuous miner. The roof 6 features numerous feather edges which are potentially unstable, and require a very high roof bolt density to stabilize. The shape is not particularly adaptable to facilitating longwall extraction of strata adjacent to the roadway. If a conventional drum type continuous miner were to be packed up to tilt the chassis to give an inclined roof parallel to the strata then the resultant floor 8 would share the same inclination as the roof. Such an inclined floor would have too steep a cross grade for machinery such as shuttle cars to operate.

Figure 2 illustrates a roadway 10 with a roof cut 12 parallel with the strata 14 using the present invention. This roadway has a more stable roof that, in comparison, only requires a medium roof bolt density. If adjacent strata is to be extracted with a longwall the roof line can be cut to be coincident with that of the roof of the roadway. There is minimal cross grade on the floor which facilitates the safe operation of machinery and provides a level base for the installation of conveyor or other equipment.

Referring to figures 2 to 6 there is shown a continuous miner 20 according to a first embodiment of the invention. The miner 20 has a chassis 21 and caterpillar tracks 22 driven by toothed wheels 23, by means of which the miner may be advanced across the ground. Mounted on the chassis 21 is a sub-frame 24, having parallel spaced apart arms 25. These arms 25 are mounted on the chassis 21 via bearings 26 for rotation about an axis 27. The axis 27 is generally horizontal when the miner is on horizontal ground. Rotation of the sub-frame 24 about axis 27 is controlled by hydraulic rams or jacks 28. The rams 28 extend between the arms 25 and the chassis 21. Extension causes the free end 29 of the sub-frame 24 to move upwards and retraction causes downwards motion. The jacks are powered from the continuous miner's hydraulic system. This arrangement of the continuous miner follows current practice.

Mounted on the free end 29 of the sub-frame 24 is a cutting head 30. The cutting head 30 includes three cutter drum assemblies 32 mounted on trunnion arms 34 of gear case 36

for rotation about drive axis 38. The cutter drum assemblies 32 are driven by motors 40 mounted on the rear of the gear case 36. Drive is via reduction gears in gear case 36 and, optionally, epicyclic gears within the cutter drum assemblies 32. The motors 40 are preferably electric motors but hydraulic or other motors may be used. The arrangement of the cutting head 30 is not critical to the invention and this configuration is substantially the same as that of many conventional cutting heads. However, in contrast to existing continuous mining machines, the cutting head 30 is not mounted rigidly to the sub-frame 24. Instead the cutting head 30 includes or is mounted upon shaft 42, which extends substantially perpendicular to the axis 38 of rotation of the cutter drum assemblies 32. The shaft 42 is mounted on the sub-frame 24 via bearings 44 for rotation about its axis 46. The bearings may be thrust bearings or separate thrust bearings may be provided. The bearings are mounted on the sub-frame 24.

Alternatively the cutter head may be powered using an inboard motor. In such a case the driving motor may be housed within shaft 42.

The shaft 42, which supports the gear case, can be rotated clockwise and anti-clockwise by hydraulic rams powered by the hydraulic system of the continuous miner. This causes the cutting drum to be tilted transversely to the centre line of the continuous miner.

The sub-frame 24 includes a rotating mechanism to rotate and control the rotation of the shaft 42, and hence the cutting head 30 about the axis 46.

In the embodiment of figures 2 to 6 there are mounted on the sub-frame 24 two pairs of opposed hydraulic rams 48. Each pair of rams has opposed cylinders 50 and a single piston shaft 52 extending therebetween. The end of the shaft 42 has two diametrically opposed pins 54, each of which is engaged by a piston shaft 52. By causing the piston shafts 52 to move in opposite directions the shaft is caused to rotate. This causes the cutting drum to be tilted transversely to the chassis of the continuous miner. When at a desired position the rams are "locked" and the shaft 42 is prevented from moving.

Further, independent locking devices may be provided to lock the inclination of the cutting drum. These may include brakes or clutches to engage and lock the shaft 42 against transverse rotation. Accordingly, a locking mechanism 43 may be provided that

engages the periphery of the shaft 42 to selectively prevent rotation. The locking means may comprise a pair of opposed brake pads 45 and actuators 47 that are selectively operated to grasp the shaft 42. Another arrangement could be a multi-plate brake mounted upon shaft 42 with actuators operating parallel to shaft 42. Other means of locking the inclination may be used. For example, the locking means may include one or more locking pins that engage in appropriate recesses or notches. These recesses may be provided on the shaft 42 itself or on a separate castellated disk or nut.

The use of pairs of opposed pistons is not essential. If desired a single ram may be connected to each pin. When two or more offset pins or their mechanical equivalents are used the rams may be single or double acting. Alternatively, a single double acting ram may be used to rotate the shaft in both directions.

The use of hydraulic rams and offset pins or similar for the rotating mechanism is preferred. The rotation of the shaft 42 may be actuated by other means. For example a ring gear may be mounted on or connected to the shaft and rotated by one or more motors. These motors may be electric, hydraulic, pneumatic or other types of motors. However, it is desirable that the rotating mechanism is substantial as large reaction forces and torques can be generated by the reaction of the cutting picks on the mining face.

The machine may be configured to have a human operator sit in an onboard cab and manually operate the machine, or the machine can be remotely operated by an umbilical cord or radio control.

In operation, the cutting head 30 is elevated to a suitable sumping horizon, the cutting head caused to rotate about its drive axis 38. The machine is then propelled into the face using tramming tracks at a level above the intended ground level so as to cut into the strata. The rams 26 are than extended to raise the cutting head 30 to the desired roof height, cutting away strata material. The shaft 42 and cutting head 30 are also rotated to align the cutting head with the inclination of the seam. This may occur before the rams 26 are extended, whilst the rams are extending or after the rams have extended to the desired roof height. At the end of the upwards cutting action the roof profile is

substantially parallel to the bedding plane of the seam. The rams are then retracted, so lowering the cutting head 30 and cutting away strata material. The shaft 42 and cutting head 30 is rotated in the opposite direction to a desired alignment. This is usually so as to be aligned with the chassis or to be horizontal. However, the head may be deliberately angled transversely to the horizontal to provide a floor with a transverse slope. The levelled cutting head 30 is then taken down to the required floor level and the floor trimmed.

The coal or mineral which has been cut falls onto the loading shovel of the continuous miner and is moved to the flight chain by means of gathering arms or rotating paddles. The flight chain then conveys the coal or mineral to the rear of the machine where it is loaded into vehicles or loaded onto a conveyor system.

Because the cutting head 30 may be rotated relative to the chassis, the floor may be cut horizontal or substantially horizontal despite any transverse inclination of the chassis. In addition transverse changes of grade to the floor may be cut.

Cutting the roof parallel to the bedding plane reduces feather edges and promotes roof stability. Cutting the roof parallel to the bedding plane allows the developed roadways to be more effectively integrated in the general support systems for long wall operations in steep seams.

The embodiment of figures 3 to 6 shows the sub-frame hinged directly to the continuous miner's chassis and pivoted to move the cutting head up and down. However, the sub- frame may be mounted on a secondary slide that slides horizontally relative to the chassis. Thus the sub-frame may be independently advanced into the face whilst the chassis remains stationary while sumping and cutting is in progress.

It is desirable for the unit to be semi automatically controlled to maximise the cutting rate during sumping, slewing and levelling the head and to automatically set the required angle of slew, subject to over ride, and to prevent the head from being inadvertently levelled at the top of the cut. Accordingly the continuous miner 20 may include a control system 60 for controlling height and inclination of the cutting head. The control system includes a human interface 62 and sensors 64 for determining the transverse inclination

of the cutting head 30. Various parameters maybe input to the system via the interface 62. These parameters include the upper and lower cutting heights, the angle of the head at the upper cutting height and the angle of the head at the lower cutting height. During operation the control system may cause the head to oscillate up and down, by control of rams 26 whilst automatically rotating the cutting assembly 32 about axis, using opposed rams.

Inclination of the cutting head may be detected absolutely, relative to horizontal or relative to the chassis. Inclination relative to the chassis may be detected by measuring the rotation of the shaft relative to the sub-frame 24 or the position of the opposed rams. Where inclination is relative to the chassis, preferably the absolute transverse inclination of the chassis is also detected so that absolute inclination of the cutting head may be calculated.

The unit may be used in conjunction with shuttle cars, or other forms of wheeled haulage, or some form of continuous haulage system. The machine may be fitted with roof bolting rigs and with scrubber(s) for dust management.

The arrangement of the embodiment of figures 3 to 5 is suitable for retrofit to many existing continuous drum type mining machines. As mentioned, in many machines the cutting head is mounted directly onto a sub-frame that is pivotably mounted on the chassis. An existing mining machine may be modified by replacing the existing sub- frame with a sub-frame similar to the sub-frame 24 of the embodiment and providing an adaptor, pivotably mounted on the sub-frame to which the existing cutting head nay be attached.

Figures 7 to 8 show a continuous miner 200 according to a second embodiment of the invention. The miner has a chassis 110, movable sub-frame 112 and a cutting head 114. The cutting head 112 is substantially the same as that of the first embodiment and is mounted on the sub-frame 112 via shaft 116 for rotation about the axis 117 of the shaft 116. Rotation of shaft 116 relative to sub-frame 112 is controlled via jacks 118 in a similar manner to the first embodiment.

The sub-frame 112 is not pivotably mounted to the chassis but is height adjustable by

way of rams 120. Preferably each arm 122 of the sub-frame 112 has a front ram 120a and a rear ram 120b. The back of the sub-frame bears against bracing 121 and slides vertically up and down against the bracing 121. Loads are transferred from the sub-frame to the chassis via the bracing 121. The rams 120 are preferably pivotably mounted to at least the chassis and optionally to the sub-frame. By changing the length of the rams the sub-frame may be caused to rise or fall. If all the rams are extended the same amount the sub-frame rises or falls substantially parallel to the chassis. If the front rams 120a extend a different amount to the rear rams 120b, the fore-aft inclination of the sub-frame changes.

Figures 9 to 11 show a continuous miner 150 according to a third embodiment of the invention. The miner has a chassis 152, movable sub-frame 154 and a cutting head 156. The cutting head 156 is fixedly mounted on the sub-frame 154. There is no rotational mounting of the cutting head 156 on the sub-frame 154 and the cutting head 156 may be a conventional cutting head. The sub-frame 154 is mounted to the chassis 152 in a similar manner to the second embodiment and is not pivotably mounted to the chassis. The sub-frame is mounted by way of rams 158, 160. The left hand arm 162 of the sub- frame 154 has a front ram 158a and a rear ram 158b. The right hand arm 164 of the sub- frame 154 has a front ram 160a and a rear ram 160b the rams 158, 160 are mounted to the sub-frame by way of universal joints 162. By changing the length of the rams the sub-frame may be caused to rise or fall. If all the rams are extended by the same amount the sub-frame rises or falls substantially parallel to the chassis. If the front rams 158a & 160a extend a different amount to the rear rams 158b & 160b, the fore-aft inclination of the sub-frame changes. If the right hand rams extend a different amount compared to the left hand rams 158 the transverse inclination of the sub-frame and the cutting head may be adjusted. Thus the transverse inclination of the cutting head may be adjusted, so as to enable cutting of, for example, an inclined roof and a horizontal floor. Loads are transferred to the chassis via bracing 162.

The use of embodiments of this invention allows the inherent high rate of production of the cutting drum of a continuous miner to be achieved and the drum to be tilted transversely thus: -

1. Allowing the roof to be cut at the required inclination with the continuous miner standing on a floor with no cross grade.

2. Enabling horizon transitions to be cut in the floor from roadways driven on full dip to horizontally floored roadways driven on strike, and all directions in between.

3. Enabling adjustments to be made to the inclination of the floor without the need to resort to packing under the continuous miner's tracks.

4. Can be fitted to new equipment or retrofitted to many existing drum type continuous miners. The individual design of the swivel mechanism may be varied to adapt to the specific design and configuration of the machine to be retrofitted.

It will be apparent to those skilled in the art that many obvious modifications and variations may be made to the embodiments described herein without departing from the spirit or scope of the invention.