GB2092641A - Mining equipment - Google Patents

Abstract

Mining equipment for steering the cutting horizon (10) of a mining machine cutter (2) which is mounted on a ranging arm (3) and which makes repeated cutting traverses, comprises a boom (30) pivotally mounted on a support housing (31) fixedly secured to the ranging arm (3). Means are provided for urging the boom towards a rock or mineral boundary (10) to sense the cutting horizon made by the cutter on a previous traverse and sensor means sense the pivotal position of the boom with respect to the ranging arm. Control means control the current cutting horizon made by the cutter in accordance with the sensed position of the boom. <IMAGE>

Description

SPECIFICATION Mining equipment This invention relates to mining equipment for use in steering the cutting horizons of mining machines.

In particular, although not exclusively, the present invention relates to mining equipment for use in steering a rotary cutter head mounted on a ranging arm provided on a longwall mining machine, the equipment being adapted to sense a cutting horizon made on a previous traverse of the machine along the face and to steer the current cutting horizon in accordance with the sensed previous cutting horizon.

An object of the present invention is to provide such mining equipment which is simple, robust and reliable and suited to the arduous conditions encountered on a longwall face in an underground mine.

According to the present invention mining equipment for steering the cutting horizon of a mining machine cutter which is mounted on a ranging arm and which, in use, makes repeated cutting traverses, comprises a boom movably mounted with respect to the ranging arm, means for urging the boom towards a rock or mineral boundary to sense a cutting horizon made by the cutter on a previous traverse, sensor means for sensing the position of the boom with respect to the ranging arm, and control means for controlling the current cutting horizon made by the cutter in accordance with the sensed position of the boom.

Preferably, the control means comprises a hydraulic control valve provided with a resiliently biassed plunger, and the sensor means comprises an abutment movable with the boom and adapted to be contacted by the plunger.

Preferably, the abutment has three alternative abutment steps associated with three alternative operational modes of the control valve, respectively.

Conveniently, the mining equipment comprises means for sensing a roof cutting horizon and for controlling a floor in accordance with the sensed roof cutting horizon.

By way of example only, two embodiments of the present invention will be described with reference to the accompanying drawings, in which: Figure 1 is an incomplete, diagrammatic side elevation of a mining machine provided with mining equipment constructed in accordance with the present invention, the machine is shown in an operational position; Figure 2 is an end view of Figure 1; Figure 3 is a hydraulic circuit diagram including the mining equipment constructed in accordance with a first embodiment of the invention; and Figure 4 is a hydraulic circuit diagram including mining equipment constructed in accordance with a second embodiment of the present invention.

Figures 1 and 2 show a ranging drum shearer coal winning machine which comprises a body 1 and a rotary cutting drum or head 2 mounted on a ranging arm 3 and which in operation repeatedly traverses to and fro along an armoured face conveyor 4 extending along a longwall working face such that the rotating cutting drum wins and loads coal from the working face 5. The single ranging arm 3 is supported in a pivotal mounting for movement about a generally horizontal axis 6, the pivotal movement of the ranging arm being controlled by two hydraulic rams 7 and 8 connected between the body 1 and the ranging arm 3. With other mining machines only one ram is provided to range the arm. An electric drive motor housed within the body of the machine is drivably connected to gear mechanism extending along the arm to drivably engage the cutter drum which thereby is rotated about an axis 9.

The arrangement is such that as the machine traverses along the working face in one direction (indicated by arrow x in Figure 1) the ranging arm 3 is raised under the action of the rams 7 and 8 such that the cutting drum 2 is in a raised operational position adjacent to the mine roof 10.

In this operational position the cutting drum forms two mineral cut profiles 10 (i.e. the mine roof) and a lower bench profile 11.

When the machine next traverses along the working face in the opposite direction to that indicated by arrow x, the ranging arm 3 is lowered under the action of the rams 7 and 8 such that the cutting drum 2 is in a lowered operational position adjacent to the mine floor 12. In this position the cutting drum forms one rock or mineral cut profile 12 (i.e. the mine floor) and removes the mineral left by the machine on its previous traverse in the direction x, i.e. the cutting drum removes the mineral below the previously formed bench profile 11.

In Figures 1 and 2 the cutting drum is shown on its upper cutting horizon forming the mine roof 10 and leaving layer 13 of roof mineral beneath the rock strata 14 overlying the mineral seam. When winning mineral on its lower cutting horizon the cutting drum forms the mine floor 12 at the boundary between the mineral seam on the underlying rock strata 15.

The winning machine comprises an underframe having a lowermost section 15 provided with two pairs of feet 17, 18, each foot being adapted to slide along a tubular trapping rail 19 extending along the goaf side of the conveyor 4 and each foot 18 being adapted to slide along flanged formation 20 extending along the working face side of the conveyor. The underframe also has an uppermost section 21 upon which the machine body 1 is supportedly mounted and which is pivotally connected along one side to the adjacent side edge of the lowermost section 16 by a longitudinally extending hinge arrangement 22.

Movement of the uppermost section 21 about the hinged arrangement is controlled by the action of two generally vertical hydraulic rams 23. The underframe 16, 21 is known as a roll type underframe which enables the machine to be rolled about an axis 25 substantially parallel to the machines longitudinal axis to steer the cutting drum along a desired cutting horizon. Such a steering action tends to prevent the formation of steps in the mine floor or mine roof due to steering adjustments.

The mining machine shown in Figures 1 and 2 also is provided with means 26 for detecting the thickness of roof mineral left by the machine on the immediately proceeding roof cutting traverse and for deriving a signal indicative of the sensed thickness. The derived signal is fed to steering control means (not shown) which control the rams 23 to maintain the machine's cutting horizon at a desired level with the mineral seam. The means 26 may for example comprise a probe for detecting natural gamma radiation emitted from the overlaying strata 14 and attenuated by its passage through the roof layer 13. Alternatively, the means 26 may comprise a source and detector of radiation or of a sonic or ultra sonic signal.

The mining machine of Figures 1 and 2 also is provided with mining equipment constructed in accordance with the present invention, the equipment comprising a boom 30 which is pivotally mounted on a support housing 31 fixedly secured to the ranging arm 3 and which is urged to contact the mine roof 10 under the action of a hydraulic ram 32 (shown only in the circuit diagrams Figures 7, 3 and 4). As seen in Figure 2 the boom 30 is urged to contact the mine roof formed on the immediately previous roof forming traverse. Figure 1 shows the boom 30 to contact the mine roof substantially directly above the axis of rotation 9 of the cutting drum. Thus, the boom is arranged to sense the cutting horizon taken by the machine along its immediately previous mine roof forming traverse.

Figure 3 illustrates that fluid is drawn back from tank via two filters 40 and 41 by two driven pumps 42 and 43 having drive motors 44 and 45, respectively. The pump arrangement 42, 44 feeds pressure fluid to actuate the two rams 7 and 8 to control movement of the ranging arm 3. The pump arrangement 43,45 feeds pressure fluid to activate the ram 31 urging the boom to pivot about its support mounting to contact the mine roof.

The pump arrangement 42, 44 feeds pressure fluid into a line 46 provided with a pressure relief valve 47 to a manually operated flow control valve 48 having detent means 49 for maintaining the valve in one or other of its selected operational modes. The valve 48 is provided with an operating handle 50 which is inter-locked with a handle 51 of a flow control 52 provided in line 53 feeding pressure fluid from the pump arrangement 43,45.

In Figure 3 the valve 48 is shown in a "manualselect" mode in which pressure fluid in line 46 is fed to a manual flow control valve 60 provided in line 61. The valve 60 is a three position valve having a central neutral mode to which the valve is resiliently biassed and two operational modes in each of which pressure fluid is fed alternatively along lines 62 or 63 to activate the aforementioned rams 7 and 8 to range the ranging arms 3 about its pivotal mounting. The valve 60 has a handle 64 which is manually activated by the machine operator until the rotating cutting drum reaches a desired height within the mineral seam. The handle 64 then is released allowing the valve to return to its neutral mode. The lines 62 and 63 are provided with pilot operated stop valves 65 and 66, respectively, which maintain a hydraulic lock in the rams 7 and 8 unless one of the lines is pressurised.

In its second operational mode the valve 48 is arranged to feed pressure fluid from the line 46 into a line 70 leading to a flow control valve 71 which has three alternative operational modes and which is provided with a resiliently biassed plunger 72 having a resilient bias 74. In Figure 3 the plunger is shown with the valve 71 in its neutral mode feeding fluid to exhaust line 75. In its two operational modes the valve 71 is adapted to feed pressure fluid along line 76 or 77 to activate the rams 7 and 8 to range the ranging arm to adjust the cutting horizon of the cutting drum.

The operational position taken up by the plunger 72 is determined by a three step abutment 80 which is contacted by a roller head 81 on the plunger. The three steps of the abutment are associated with the three operation modes of the valve 71, respectively. In Figure 3 the plunger head 81 is shown abutting the middle or second step of the abutment and the valve, therefore, is moved against its resilient bias 74 into its central neutral operational mode.

For the sake of convenience, in Figure 3 the abutment 80 is indicated twice (on different scales). As aforementioned, the abutment is shown in association with the valve 71 with the head of the plunger 72 contacting the abutment.

The same abutment 80 also is shown on a reduced scale fixedly mounted on the boom 30, the abutment being shown to extend in the form of an arc around the pivotal axis for the boom.

Thus as the boom pivots around its pivotal mounting the different steps of the abutment are moved to co-operate with the plunger head to urge the valve 71 into its different operational modes.

With the flow control valve 48 in the "manualselect" mode as shown in Figure 3 the interlocked valve 52 is in an operational mode to feed pressure fluid along line 85 to retract the ram 31 to urge the boom 30 away from an exposed position adjacent to mine roof and towards the relatively sheltered region of the ranging arm.

Thus, when the ranging arm is being ranged manually the boom 30 is stored in a protected zone. However, when the valve 48 is moved to an "auto-select" mode in which pressure fluid is fed to the valve 71, the valve 52 is simultaneously moved into an operational mode in which pressure fluid is fed along line 86 tending to extend the ram 31 to urge the boom 30 to contact the mine roof.

Typically, the arrangement is such that the ram 31 urges the boom to pivot to contact the mine roof and at this condition the plunger head 81 abuts the central or middle step of the abutment (as shown in Figure 3). As the machine traverses along the longwall face with its cutting drum in its raised position forming the mine roof, the boom 30 is maintained in contact with the mine roof formed on the immediately previous roof forming traverse.

Upon the feet 17, 1 8 of the machine negotiating an undulation in the longwall face, there is a tendency for the cutting drum (which as seen in Figure 1 is outboard of the machine body) to lower away from the boundary of the mineral seam with the overlying strata and thereby a greater thickness of mineral tends to be left in the roof layer.However, upon the boom 30 sensing the difference between the current and the immediately previous cutting horizons, the boom pivots under the action of the ram 31 until when a sufficiently large amount of pivotal movement of the boom has taken place the plunger head 81 contacts another step of the abutment allowing the operational mode of the valve 71 to change to feed pressure fluid along line 76 or 77 to desirably adjust the operational positions of the rams 7 and 8 to range the ranging arm until the current cutting horizon of the cutting drum substantially is the same as that of the immediately previous roof forming traverse.Upon the current cutting horizon of the cutting drum being corrected the boom has been pivoted by its reaction against the mine roof and against the action of the ram 31 until the plunger head 81 again contacts the central step of the abutment 80 and the valve 71 is returned to its central, neutral operational mode with the rams 7 and 8 hydraulically locked.

Upon the cutting drum tending the cut towards the boundary between the mineral seam and the overlying strata such that a reduced thickness of mineral tends to be left in the roof layer 13, the boom again senses the difference between the current and the immediately previous cutting horizons and again corrective measures are taken.

In this case the boom pivots such that the plunger head 81 contacts the other operational step of the abutment 30 and the valve is moved against its resilient bias 74 to feed fluid pressure to one or other of the lines 76 or 77 to desirably actuate the rams 7 and 8 to range the rotating cutting drum its correct cutting horizon. Upon the correct cutting horizon being achieved the boom has pivoted sufficiently to allow the plunger head to contact the central step of the abutment and once again the valve 71 takes up its central neutral operational mode.

The mining equipment operates along the full length of the longwall face tending to maintain the current and the immediately previous cutting horizons at the same level.

Throughout the traversing of the machine the cutting head is steered along its floor winning cutting traverse by the aforementioned steering means 26 which as previously explained steers the cutting drum by suitable adjustment of the roll type steering underframe.

In other embodiments of the invention the steering means 26 are dispensed with.

In still other embodiments of the invention the abutment is adjustably mounted relatively to the boom in order to facilitate pre-set adjustment.

Figure 4 shows the hydraulic circuit diagram for a second embodiment of the present invention.

The second embodiment differs from the first described embodiment in that the inter-locked manually operated valve 52 is replaced by a pilot operated valve 90 having pilots 91 and 92 connected via pilot lines 93 and 94 to the manually operated valve 48. Pressure reducers 95 are provided in the lines 93 and 94.

The operational function of the pilot operated valve 90 is similar to that of the aforementioned valve 52. However, the inter-lock is hydraulic rather than mechanical. The same reference numbers are used for similar items in Figures 3 and 4.

A pressure relief valve 47 is provided in the line 53 leading from the pump arrangement 43, 45 and a non return valve 98 is provided in line 70 to the valve 71. The operation otherwise substantially is as previously described with reference to Figures 1, 2 and 3.

In other embodiments of the invention the three step abutment 80 is replaced by an abutment having a continuously varying abutment surface.

Claims (7)

1. Mining equipment for steering the cutting horizon of a mining machine cutter which is mounted on a ranging arm and which, in use, makes repeated cutting traverses, comprising a boom movably mountable with respect to the ranging arm, means for urging the boom towards a rock or mineral boundary to sense a cutting horizon made by the cutter on a previous traverse, sensor means for sensing the position of the boom with respect to the ranging arm, and control means for controlling the current cutting horizon made by the cutter in accordance with the sensed position of the boom.

2. Equipment as claimed in claim 1, in which the control means comprises a hydraulic control valve provided with a resiliently biassed plunger, and the sensor means comprises an abutment movable with the boom and adapted to be contacted by the plunger.

3. Equipment as claimed in claim 2, in which the abutment has three alternative abutment steps associated with three alternative operational modes of the control valve, respectively.

4. Equipment as claimed in claim 1,2 or 3, comprising means for sensing a roof cutting horizon and for controlling a floor in accordance with the sensed roof cutting horizon.

5. A mining machine having a cutting drum which is mounted on a ranging arm and which, in use, makes repeated cutting traverses, and comprising mining equipment as defined in any one of the preceding claims.

6. Mining equipment for steering the cutting horizon of a mining machine cutter which is mounted on a ranging arm and which, in use, makes repeated cutting traverses substantially as described herein and substantially as shown in Figures 1 and 2, or Figure 3 or Figure 4 of the accompanying drawings.

7. A mining machine having a cutting drum which is mounted on a ranging arm and which, in use, makes repeated cutting traverses, and comprising mining equipment substantially as described herein and substantially as shown in Figures 1 and 2 or Figure 3 of Figure 4 of the accompanying drawings.