GB2077831A

GB2077831A - Positional control system

Info

Publication number: GB2077831A
Application number: GB8019859A
Authority: GB
Original assignee: DOWTY MINING DEV Ltd
Current assignee: DOWTY MINING DEV Ltd
Priority date: 1980-06-18
Filing date: 1980-06-18
Publication date: 1981-12-23
Also published as: GB2077831B; DE3123824A1

Abstract

A positional control system includes adjusting means for temporarily moving a member, for example a cantilever beam 11 of a self-advancing mine roof support 13, 14, out of the path of a power-driven device, for example a mineral-cutting machine 31, approaching the member. Automatic means are provided which are operable, in the event that the adjusting means fails to so move the member out of that path, to cut off the power to the power- driven device and thereby arrest its movement. <IMAGE>

Description

SPECIFICATION Positional control system This invention relates to a positional control system for effecting adjustment in the position of a member in relation to a moving device and intended to prevent the occurrence of collision between said device and said member.

According to the invention a positional control system includes adjusting means for temporarily moving a member out of the path of a powerdriven device approaching the member and automatic means operable, in the event that said adjusting means fails to so move said member out of said path, to cut off the power to said device and thereby arrest its movement.

The member may be a self-advancing roof support, or a part thereof, suitable for use in mineral-mining operations and the power-driven device may be a cutting machine arranged to move along a mineral face and to cut the mineral as it advances along the face.

A large number of such supports may be arranged along the mineral face in customary manner.

Each roof support may include a cantilever beam, the free end portion of which is intended to support the mine roof immediately adjacent the mineral face, this beam, when necessary, being movable both with respect to the main portion of the support and temporarily out of the path of the machine sufficiently to permit the passage of the machine past the support and along the mineral face.

Each roof support may also carry a so-called "sprag", for example, on or adjacent the free end portion of the cantilever beam for support of the mineral face.

One embodiment of the invention will now be described by way of example with reference to the accompanying diagrammatic drawings, of which: Figure 1 is a plan view of a plurality of roof supports and a mineral-cutting machine disposed at a mineral face, and, Figure 2 is a control circuit associated with two of the roof supports and with the cutting machine shown in Figure 1.

The roof supports are of the hydraulicallyoperable self-advancing type and each comprises a cantilever beam 11 which is extendible and retractable with respect to the main portion 12 of the support by adjusting means in the form of an hydraulic jack. The pair of supports shown at 13 and 14 have both of their jacks, shown at 15 and 1 6 in Figure 2, under the control of a single control valve later referred to. These two supports 1 3 and 14 are spaced apart lengthwise of the mineral face 18, there being in this embodiment seven supports, 19, 20, 21, 22, 23, 24 and 25, disposed between them. A desired number of supports precedes the support 1 3 along the mineral face, two of these being shown at 26 and 27. Similarly a desired number of supports follows the support 14 along the mineral face, three of these being shown at 28, 29 and 30.

As well as with supports 13 and 14, all of the other supports are, in a manner not shown in the drawings, connected in pairs and their jacks are arranged to be under the control of a respective single control valve for each pair. For example, of those supports shown in Figure 1, 27 and 25 form a pair, as do 26, 24; 19, 28; 20, 29 and 21,30.

A mineral-cutting machine 31, which is suitably supported on a conveyor (not shown) running longitudinally between the roof supports and the mineral face 18, comprises a main body 32, ranging arms 33 and 34 which are pivotaily mounted at each end of the body, and cutter drums 35, 36 mounted on the free ends of the ranging arms. The machine is driven along the conveyor by an electric motor (not shown), carried by the body 32, which powers pinion gearing (not shown) also carried by the body and meshing with a rack (also not shown) supported by the conveyor.

When the machine 31 is moving to the left in Figure 1, the drum 35 performs the mineralcutting operation and when the machine is moving to the right the drum 36 performs the mineral-cutting operation. Alternatively, while whichever drum which is leading is performing the advancing cut, the trailing drum may be performing a floor and/or mineral face cutting operation.

In order to permit passage of the cutting machine 31 as it moves in either direction along the mineral face 18, the cantilever beams 11 of the supports are required, as they are approached by the machine, to be retracted successively from their roof supporting positions into the main portions 1 2 of the respective supports. When the machine has passed the retracted beams they are re-extended successively so as to re-support the roof behind the advancing machine.

As shown in Figure 1, in order to provide for such passage, the cantilever beams of eight adjacent roof supports must be in their retracted condition at any one time.

The control system as for each pair of roof supports will now be described with particular reference to Figure 2, which includes the pair of roof supports 1 3, 14, together with their respective jacks 1 5 and 1 6.

A main supply line 37 passes along the installation for the supply of liquid under pressure not only to the jacks 1 5 and 16 but to the jacks of all the other pairs of supports. A main return line 38 runs parallel with the line 37. A line 39 is branched from the line 37 and taken to the single control valve 40 which is of rotary type, and a line 41 is taken from the valve to the return line 38.

The valve 40 is mounted on fixed structure close to the path of the machine 31 and includes an operating lever 42 which is engageable by an abutment 43 carried by the machine.

The jacks 1 5 and 1 6 are of double-acting type.

A line 44 is taken from the valve 40 to the lower end portion of the cylinder 45 of the jack 15 while a line 46 is taken from the upper end portion of that cylinder back to the valve 40.

A line 47 is branched from the line 44 and taken to the upper end portion of the cylinder 48 of the jack 16, while a line 49 is taken from the lower end portion of that cylinder and connnects with the line 46.

A valve 50 is provided at the lower end of the cylinder 45 and this is opened by the piston 51 of the jack 1 5, as it reaches its fully retracted position, to place a line 52 branched from the line 46 in communication with a line 53 which connects with a shuttle valve 54.

Similarly a valve 55 is provided at the lower end of the cylinder 48 and this is opened by the piston 56 of the jack 1 6, as it reaches its fully retracted position, to place a line 57 branched from the line 47 in communication with a line 58 which connects with the shuttle valve 54.

The shuttle valve 54 is associated with a singleacting piston-and-cylinder device 59 which is spring-urged to its extended condition and which is retractable under liquid pressure supplied to the annular chamber 60. A line 61 is taken from the shuttle valve 54 to this chamber for this purpose and receives its liquid under pressure from either the line 53 or the line 58 in dependence upon which of these is pressurised.

When the device 59 is fully extended its piston rod 62 lies in the path of either a cam 63 or a cam 64 formed by upstanding lugs 65, 66 carried by the machine 31. Micro switches 67 and 68 are respectively carried on the opposing faces 69 and 70 of the lugs 65 and 66. These micro switches are suitably incorporated in the electrical supply circuit of the electric driving motor (not shown) carried by the body 32 of the machine 31.

The device 59 is so constructed and mounted with respect to fixed structure that when the machine reaches the position at which the device is mounted, and the device is extended, either the cam 63 or alternatively the cam 64, depending on the direction of movement of the machine, engages the free end of the piston rod 62 and moves the device out of the path of the respective lug. The device then springs back to the position shown in Figure 2, being then disposed between the two lugs 65 and 66 and in readiness to be engaged by whichever of the two micro switches 67 and 68 is appropriate.

Shuttle valves 71, 72, 73 and 74 are respectively provided in lines 44, 46, 49 and 47.

Lines 75 and 76 are respectively taken from the shuttle valves 71 and 72 to a roof support which is eight roof supports in advance of the roof support 13. Likewise, lines 77 and 78 are respectively taken from the shuttle valves 73 and 74 to a roof support which is eight roof supports behind the roof support 14 in the series.

The control circuit is intended to ensure that the cantilever beam of one of the supports of a pair is retracted in good time before the moving cutting machine reaches the position that beam occupies when extended and to ensure also that the cantilever beam of the other support of a pair can only commence to re-extend when the machine has completely passed the position that beam is then about to re-occupy. In this way inadvertent colliding engagement of parts of the machine and of the supports is avoided.

In operation, as the machine 31, moving to the left in Figure 1, passes previously-retracted cantilever beams 11 and approaches, for example, the extended cantilever beam 11 of the support - 14, the abutment 43 moves the lever 42 in the anti-clockwise direction causing the valve 40 to open pressure line 39 to line 44. Liquid under pressure thus gains access by way of line 47 to the cylinder 48, causing retraction of the jack 1 6 and thus retraction of the cantilever beam 11 into the main portion 12 of the roof support 14, permitting passage of the machine 31 past this support.Simultaneously liquid under pressure from line 44 gains access to the cylinder 45 causing extension of the jack 1 5 and thus extension of the cantilever beam 11 from the main portion 12 of the roof support 13 right up to the mineral face 1 8 for as full support of the roof in this vicinity as possible.

On such contraction of the jack 1 6 liquid leaving the cylinder 48 passes through lines 49 and 46, valve 40 and line 41 to the main return line 38. Similarly on such extension of the jack 1 5, liquid leaving the cylinder 45 passes through line 46, valve 40 and line 41 to the main return line 38.

Further, on full contraction of the jack 1 6 the piston 56 opens the valve 55 admitting pressure liquid present in the line 57 into the line 58 and thence to the shuttle valve 54. This liquid passes by way of the line 61 into the annular chamber 60, causing retraction of the piston rod 62 of the device 59. The lugs 65, 66 moving with the cutting machine 31 and complete with their cams 63, 64 and micro switches 67, 68 freely pass the rod 62, and hence the electrical circuit to the driving motor of the machine remains complete so that the cutting machine continues to be driven along the mineral face.

If instead, during such operation, a fault occurs in the system such that the jack 1 6 fails to operate so that the cantilever beam 11 of the support 14 remains unretracted, or only partially retracted, in the face of the on-coming cutting machine 31, the valve 55 will not be opened because the piston 56 has not travelled to the inner extremity of the cylinder 48. Consequently the piston rod 62 will remain in its extended position in the path of the lugs 65, 66. As explained above, on engagement of the free end portion of the rod 62 by the cam 63 the device 59 will be moved out of the path of the lug 65 and will then spring back to the position shown in Figure 2. Thereafter the micro switch 68 will come into engagement with the rod 62, with the result that the electrical conductors to the driving motor of the cutting machine become open-circuited and the machine will come to a halt. The device 59 is designed to accommodate final movement of the machine as it comes to rest without damage to the device or the micro switch.

By so providing for automatic stopping of the cutting machine in the event of failure or partialfailure in the control circuit, collision damage to machine and roof support is avoided, so that following rectification of the control circuit fault, resumption of mineral-cutting operations can take place.

If, instead of moving to the left in Figure 1, the cutting machine moves to the right so that the drum 36 is leading in the mineral-cutting operation, the circuit operates in the converse sense. The abutment 43 moves the lever 42 in the clockwise direction so that the valve 40 places the pressure line 39 in communication with the lines 46 and 49. Thus the jack 1 5 of the support 13 contracts and the cantilever beam 11 of that support is retracted to permit passage of the machine. Simultaneously the jack 1 6 of the associated support 14 is extended to replace the cantilever beam 11 thereof in its roof supporting position. In this case, however, on complete retraction of the jack 1 5, the valve 50 is opened so that liquid under pressure passes through the line 53 and shuttle valve 54 to cause retraction of the device 59.If, however, a failure occurs in the control circuit whereby the jack 1 5 does not retract, or only partially retracts, and such that the piston rod 62 of device 59 remains in its extended position, the micro switch 67 comes into contact with the rod resulting in stopping of the driving motor of the machine and thus halting of the machine.

Since the system above-described permits the cantilever beams to be extended completely up to the mineral face in front of and behind the machine, the mine roof is very well supported along the whole length of the face with the exception of the relatively small and moving area actually over the machine as it proceeds along the face.

The control system above-described is such that a valve, as at 40, is provided in association with each pair of roof supports. Further, the shuttle valves, as at 71, 72, 73 and 74, afford operational inter-relationship of the jack of any roof support, not only with the jack of one other roof support as described with reference to Figure 2, but with the jacks of yet other roof supports ahead and rearward thereof. Thus, for example, with the cutting machine moving to the left in Figure 1, when the jack 1 5 of the support 13 is retracting, a jack of another roof support earlier in the sequence is extending, and again when the jack 1 6 of the support 1 4 is extending, a jack of another roof support later in the sequence is retracting.

Although not shown in the drawings, a triggering system is provided in association with the roof supports so that before retracting operation of the jacks 1 5, 1 6 can take place, the cantilever beam is automatically released from load-bearing engagement with the mine roof.

Conversely, the triggering system also ensures that load-bearing engagement by the cantilever beam with the mine roof only takes place after the desired extension of the beam has been effected.

In alternative embodiments of the invention a so-called "sprag" is carried at the free end of each cantilever beam for support of the vertical mineral face. In this case the control system of this invention provides means for temporarily moving each sprag away from engagement with the mineral face for the passage of the mining machine, either alternatively to, or simultaneously with, the temporary retraction of the cantilever beam.

Although in the embodiment above-described with reference to the drawings the control system is basically mechanical/hydraulic, in other embodiments it may be electrical or electrohydraulic.

Again, although the drive for the cutting machine is of rack-and-pinion type with the driving motor carried by the machine, in other embodiments other suitable driving means may be provided with the motor either again carried by the machine or alternatively mounted elsewhere.

The positional control system hereinbefore described eliminates the need for an operator to be present at or near the roof supports for manually adjusting the valves 40 associated with the respective cantilever beams. However, the valves may have an adjustable mounting so that they can be moved out of the path of the cutting machine and be thereby adapted also for manual control appropriate to certain phases of operation of the system.

CLAIMS (filed on 5th June 1981) 1. A positional control system including adjusting means for temporarily moving a member out of the path of a power-driven device approaching the member and automatic means operable, in the event that said adjusting means fails to so move said member out of said path, to cut off the power to said device and thereby arrest its movement.

2. A system as claimed in Claim 1, wherein said member is a roof support, or a part thereof, suitable for use in mineral-mining operations.

3. A system as claimed in Claim 2, wherein said roof support is of self-advancing type.

4. A system as claimed in either Claim 2 or Claim 3, wherein said power-driven device is a cutting machine arranged to move along the mineral face, thus to cut the mineral as it advances along the face.

5. A system as claimed in Claim 4, wherein a large number of said roof supports is provided along the mineral face, each support being disposed substantially at right-angles to said face.

6. A system as claimed in either Claim 4 or Claim 5, wherein each said roof support includes a cantilever beam, the free end portion of which is intended to support the mine roof immediately adjacent said mineral face.

7. A system as claimed in Claim 6, wherein said cantilever beam is movable both with respect to the main portion of said roof support and

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. By so providing for automatic stopping of the cutting machine in the event of failure or partialfailure in the control circuit, collision damage to machine and roof support is avoided, so that following rectification of the control circuit fault, resumption of mineral-cutting operations can take place. If, instead of moving to the left in Figure 1, the cutting machine moves to the right so that the drum 36 is leading in the mineral-cutting operation, the circuit operates in the converse sense. The abutment 43 moves the lever 42 in the clockwise direction so that the valve 40 places the pressure line 39 in communication with the lines 46 and 49. Thus the jack 1 5 of the support 13 contracts and the cantilever beam 11 of that support is retracted to permit passage of the machine. Simultaneously the jack 1 6 of the associated support 14 is extended to replace the cantilever beam 11 thereof in its roof supporting position. In this case, however, on complete retraction of the jack 1 5, the valve 50 is opened so that liquid under pressure passes through the line 53 and shuttle valve 54 to cause retraction of the device 59.If, however, a failure occurs in the control circuit whereby the jack 1 5 does not retract, or only partially retracts, and such that the piston rod 62 of device 59 remains in its extended position, the micro switch 67 comes into contact with the rod resulting in stopping of the driving motor of the machine and thus halting of the machine. Since the system above-described permits the cantilever beams to be extended completely up to the mineral face in front of and behind the machine, the mine roof is very well supported along the whole length of the face with the exception of the relatively small and moving area actually over the machine as it proceeds along the face. The control system above-described is such that a valve, as at 40, is provided in association with each pair of roof supports. Further, the shuttle valves, as at 71, 72, 73 and 74, afford operational inter-relationship of the jack of any roof support, not only with the jack of one other roof support as described with reference to Figure 2, but with the jacks of yet other roof supports ahead and rearward thereof. Thus, for example, with the cutting machine moving to the left in Figure 1, when the jack 1 5 of the support 13 is retracting, a jack of another roof support earlier in the sequence is extending, and again when the jack 1 6 of the support 1 4 is extending, a jack of another roof support later in the sequence is retracting. Although not shown in the drawings, a triggering system is provided in association with the roof supports so that before retracting operation of the jacks 1 5, 1 6 can take place, the cantilever beam is automatically released from load-bearing engagement with the mine roof. Conversely, the triggering system also ensures that load-bearing engagement by the cantilever beam with the mine roof only takes place after the desired extension of the beam has been effected. In alternative embodiments of the invention a so-called "sprag" is carried at the free end of each cantilever beam for support of the vertical mineral face. In this case the control system of this invention provides means for temporarily moving each sprag away from engagement with the mineral face for the passage of the mining machine, either alternatively to, or simultaneously with, the temporary retraction of the cantilever beam. Although in the embodiment above-described with reference to the drawings the control system is basically mechanical/hydraulic, in other embodiments it may be electrical or electrohydraulic. Again, although the drive for the cutting machine is of rack-and-pinion type with the driving motor carried by the machine, in other embodiments other suitable driving means may be provided with the motor either again carried by the machine or alternatively mounted elsewhere. The positional control system hereinbefore described eliminates the need for an operator to be present at or near the roof supports for manually adjusting the valves 40 associated with the respective cantilever beams. However, the valves may have an adjustable mounting so that they can be moved out of the path of the cutting machine and be thereby adapted also for manual control appropriate to certain phases of operation of the system. CLAIMS (filed on 5th June 1981)

1. A positional control system including adjusting means for temporarily moving a member out of the path of a power-driven device approaching the member and automatic means operable, in the event that said adjusting means fails to so move said member out of said path, to cut off the power to said device and thereby arrest its movement.

temporarily out of the path of the machine sufficiently to permit the passage of the machine past the support and along said mineral face.

8. A machine as claimed in any one of Claims 4 to 7, wherein said cutting machine is adapted to be supported upon a conveyor running generally parallel to said mineral face.

9. A system as claimed in Claim 8, wherein said cutting machine comprises a main body, at least one ranging arm pivotally mounted on the body and a cutter drum mounted on the free end of the or each said ranging arm.

10. A system as claimed in Claim 9, wherein said cutting machine is driven along the conveyor by an electric motor, carried by said body, which powers pinion gearing also carried by said body and which meshes with a rack supported by the conveyor thereby to drive the machine along the conveyor.

11. A system as claimed in Claim 10, wherein said adjusting means comprises an hydraulic jack, one for each said roof support, which is capable of extending and retracting said cantilever beam with respect to said main portion of the roof support.

12. A system as claimed in Claim 11, wherein each said jack has a valve associated therewith which forms part of said automatic means and which is caused to open as the jack reaches its end-of-stroke position corresponding to the retracted condition of the respective said cantilever beam.

13. A system as claimed in Claim 12, wherein a piston-and-cylinder device, also forming part of said automatic means, is so associated with said valve that when the valve is in its open position that device is in its contracted condition and when the valve is not open that device is so extended that its piston rod lies in the path of a switch, also forming part of said automatic means, which is' carried by said cutting machine.

14. A system as claimed in Claim 13, wherein said switch is arranged in circuit with said motor whereby when, with said piston-and-cyiinder device so extended, said switch engages said piston rod, it opens the circuit of said motor thereby stopping said motor and arresting movement of said cutting machine along said conveyor.

1 5. A system as claimed in any one of Claims 6 to 14, wherein each said roof support carries a sprag on or adjacent the free end portion of the respective cantilever beam for support of the mineral face.

1 6. A positional control system substantIally as hereinbefore described with reference to the accompanying drawings.