GB2164680A - Improvements relating to drum shearer-loader machines - Google Patents

Abstract

A drum shearer-loader machine 1 for underground mining, has its shearing drums 5 ventilated near their face-side end face. A liquid pump 10 which derives its motion from the driving motor of the machine 1 supplies pressurised liquid to injection nozzles 9 producing the ventilation air stream. Also a clutch 14, is provided which disconnects the drum 5 from the driving motor when the machine 1 is stationary. In response to energisation of the machine 1, but only after a delay, the clutch produces the driving connection between the driving motor and the drum 5. Consequently, the pump 10 starts up immediately upon energisation of the driving motor and supplies pressurised liquid to the nozzles 9 with the machine still stationary and ventilates the face-side drum end face 6 and the gap between the clearing plate and the drum periphery before the drum 5 starts to rotate upon operative startup of the machine 1. <IMAGE>

Description

SPECIFICATION Improvements relating to drum shearer-loader machines The invention relates to a drum shearer-loader machine for underground mining, wherein its shearing drums are ventilated near their face-side end face. To this end the machine may have a liquid pump which derives its drive motion from the machine-driving motor and supplies pressurised liquid to injection nozzles producing the ventilation air flow.

The function of the pump is to supply injection nozzles for ventilating the drum end face and the space between the drum periphery and the clearing plate with liquid which is supplied to the machine and whose pressure the pump increases. The pump may be driven by the reduction gearing of the machine, such gearing providing the driving connection between the drum and the drum-driving motor.

The reason for ventilating the gaps or spaces is to remove the gas which issues from the seam and which collects in the gaps or to dilute the resulting gas and air mixture at least to a level at which explosions cannot occur. When the machine is in movement, the required effect is provided by the continuous air flow issuing from the injection nozzles, but this is not the case when the machine is stationary and, since the pump is stationary, the injection nozzles do not operate. There is therefore an increased risk of explosion in these zones precisely when a drum shearer-loader machine starts up; because of this risk the nozzles need to start operating before the machine starts up.

When the pressure liquid is supplied directly to the injection nozzles through a line along the face, start-up of a machine causes no problems because the injection nozzles can operate independently of the machine. They can be supplied with pressure liquid for a variable time before switch-on of the machine and ventilate the gaps previously referred to.

However, this is not the case with drum shearerloader machines which are supplied with relatively low pressure liquid through a line along the face and which have in or on them a liquid pump for producing the operating pressure of the water for supplying the injection nozzles. In the latter case the injection nozzles cannot be supplied with pressure liquid while the machine is stationary since the liquid pump stops whenever the or each motor driving the machine stops.

It is the object of the invention to enable the injection nozzles for ventilating a drum shearerloader machine to be supplied with pressure liquid, by means of a liquid pump driven by the machinedriving motor, even when the machine is stationary, namely when the shearing drum is not rotating and the machine is not advancing.

According to the invention, there is provided a drum shearer-loader machine for underground mining, having shearing drums which are to be ventilated near their face-side end face, the machine having at least one liquid pump which derives its drive motion from the machine-driving motor which will supply pressurised liquid to injection nozzles producing the ventilation air flow, and incorporating a clutch which disconnects the shearing drum from its driving motor when the machine is stationary and which, in response to energization of the machine, produces, but only after a delay, the driving connection between the motor and the shearing drum.

The driving motor which starts up when the machine is switched on now drives the liquid pump but not the drum. The drum is cut in after a delay of, for instance, 20 or 30 seconds, which is sufficient time for adequate ventilation of the gap between the drum periphery and the clearing plate or of the gap between the face and the drum end face before the work of picking begins. Consequently, even after a machine has been stationary for a long time, detonatable accumulations of gas in the gaps referred to can be removed sately before mining recommences.

The clutch may have a disengaging or release spring and an actutating cylinder for engaging the clutch and energisable by the pressure of the liquid pump or by the pressure of a lubricant pump, the pressurised liquid being supplied to the actuating cylinder by way of an adjustable restrictor. The spring ensures that the clutch releases upon stoppage of the machine and upon the pressure in the actuating cylinder decreasing, while the restrictor ensures that the operative movement of the actuating cylinder experiences delay and that a predertermined time must elapse before the driving connection can be provided between the drum and the motor.

Another possibility is for the clutch to have an electrical actuating device which engages it against the force of the release spring and which receives its driving power by way of a time relay actuated upon energisation of the machine. In this construction engagement of the clutch is delayed by the time relay long enough to ensure that the drum starts to rotate only once the gaps have been properly ventilated.

In the case of machines having a liquid pump operating in both directions of rotation, a freewheel clutch can provide the driving connection between the shearing drum and the drum-driving motor, means being provided such that, upon energisation of the machine, the drum-driving motor rotates initially for a predetermined period in a first direction which does not allow the freewheel clutch to drive the shearing drum, and then rotates, but only after the motor has come to a standstill in the second direction enabling the freewheel clutch to transmit the drive to the shearing drum.Since the pump delivers in both directions of motor rotation, it provides an immediate supply of pressurised liquid to the injection nozzles at start-up of the driving motor and ventilates the face-side end face of the drum and the gap between the clearing plate and the drum periphery in the 20 or 30 seconds before the driving motor reverses and then drives the drum as well as the pump.

For operation of a drum shearer-loaded machine in this way it is recommended to provide a reversing contactor whose two power contactors connect the machine-driving motor to the power supply mains seriatim, the two power contactors being so operable seriatim by means of a time relay that upon energisation of the machine the motor runs initially in said first direction of rotation and subsequently, but only after the dropping of the corresponding power contactor, in said second direction, after a period long enough for the motor to come to a standstill, whereupon the other power contactor is actuated. A circuit arrangement of this kind automatically ensures reversal of the driving motor and, therefore, adequate ventilation of the gaps before the machine starts up.

The invention may be performed in various ways and preferred embodiments thereof will now be described with reference to the accompanying drawings, in which: Figure 1 is a view in partial section of a ranging arm of a shearing drum installed in onw embodiment of the invention; Figure 2 shows another embodiment of the invention in a manner similar to that of Figure 1; and Figure 3 shows a circuit diagram for the motor driving the shearing drum and the liquid pump of either of these two embodiments.

The drum shearer-loader machine 1 shown in Figure 1 has a ranging arm 2 pivotable about a horizontal axis 3 by a hydraulic ram (not shown).

The arm 2 carries at its end a shearing drum 5 mounted for rotation around a horizontal axis 4.

To prevent CH4 accumulations from causing explosions near the face-side end face 6 of the drum 5 and/or in the gap between the drum periphery and the clearing plate (not shown) of the drum 5, the drum end face 6 which is in the back of the cut and the gap between the drum periphery and the clearing plate are ventilated.

Thus the arm 2 has on the goaf side a supply duct 7 which extends over the length of the arm 2 and which enters a drive shaft duct 8 near the drum axis 4. An injection nozzle 9, disposed ahead of the duct 8, is connected to a liquid supply line (not shown) and produces the air flow which goes to the drum end face 6 by way of the duct 7. The water supplied to the nozzle 9 is raised to the required pressure by a liquid pump 10. The pump 10 is flange-connected to the ranging-arm side wall distal from the mineral face so as to be coaxial with the axis 3 of the arm 2 and is drivingly connected to the driving motor (not shown) of the machine 1.

Gearing whose gears 11, 12 are rotatably mounted on stationary shafts in the arm 2 provides the driving connection between the machine-driving motor and the drum 5. The last gear 11 is coaxial with the axis 4, is borne by two rolling bearings 13 and receives a freewheel clutch 14 in its central bore. The clutch 14 receives, in a bore which is central of the drum axis 4, the tubular duct 8 and engages by way of its outer toothed ring in internal toothing of the gear 11, the latter toothing being disposed between the two rolling bearings 13. The clutch 14 transmits the rotation of the machine-driving motor 16 to the drive shaft of the reduction gearing 15 in the drum 5 only in one direction, namely the operative direction of rotation of the drum 5.

Referring to the circuit diagram of Figure 3, conductors RST form an electric power supply networl for energising the machine-driving motor 16. Two parallel motor contactors 17a , 17b , each actuated by a respective relay 18, 24 enable the motor 16 to run in either direction.

To ensure that there has been adequate ventilation of the face-side space in front of the drum end face 6 and/or of the space between the drum 5 and the clearing plate before the drum 5 starts to ro- tate, the motor 16 is at each switch-on operated to run briefly in a direction of rotation such that the clutch 14 cannot transmit such rotation to the drum reduction gearing 15. This brief period of idle rotation (approximately 20 seconds) is sufficient to ensure adequate ventilation of the various gaps mentioned. Only after this brief period does the motor 16 reverse automatically and drive the drum 5 in the operative direction determined by the position of its picks 19.

Upon closure of the "on" switch 20 on the may chine 1, a control pulse is triggered by way of a control line 36 in a unit 21 and a switch 22 closes.

Relay 18 in circuit 23 is now energised and interrupts the two circuits 25, 26 by opening two switches 27, 28. Relay 18 also actuates the power contactor 17a of the reversing contactor 29 so that the motor 16 runs in the direction which the clutch 14 cannot transmit. However, the pump 10, which is, for instance, a radial piston pump and delivers in both directions of rotation, is driven during this rotation of the motor. The pump 10 therefore supplies the nozzle 9 with pressurised liquid and ensures adequate ventilation of the drum end face 6 and of the gap between the drum periphery and the clearing plate.

This period in which the machine 1 is still stationary but the still stationary drum 5 is being ventilated lasts, for instance, for 20 seconds until a time relay 30 in circuit 31 picks up and opens switch 32 of circuit 23 and closes switch 33 of circuit 25. Circuits 23, 26 are now open and relay 18 has dropped and isolated motor 16 from the mains supply RST. Also, the switch 28 has returned to its closed position. The motor 16 is now de-energised for example for 2 seconds, the time being determined by the energising time of relay 34 of the circuit 25. Only after this period does relay 34 pick up an close the switch 35 of circuit 26. Relay 24 then picks up and actuates power contactor 176,which reconnects motor 16 to the mains RST so that the motor 16 now runs in the operative direction. The machine 1 is therefore ready for operation since its drum 5, which has been ventilated on its end face and/or between its periphery and the clearing plate, now rotates in a direction to suit the position of its picks 19 and the pitch of its whorls 37.

In the embodiment shown in Figure 2, the arm 2 receives a clutch 38 connecting the last gear 39 of ranging-arm gears 39, 40 to the input shaft of the drum reduction gearing 15. In this embodiment the final gear 39 has a clutch (not shown in greater detail) in which a moving part 41 engages. When engaged the part 41 connects the reduction gearing 15 to the gears 39, 40. A spring 42 disposed in a cylinder 43 coaxially of the drum 5 acts continuously by way of a piston 44 on the part 41 to keep this part in a released condition. In this state the spring 42 has pressed the piston 44 back into its outer dead centre position and forced the part 41 out of the bore in the gear 39. When the motor 16 starts up, the liquid pump 10 disposed on the outside of the ranging arm centrally of its pivot axis 3 rotates and ventilates the various gaps associated with the drum 5. Also, by way of the line 45, the pump 10 acts on the piston 44 of cylinder 43 and moves the part 41 towards the gear 39. This step lasts for a time determined by an adjustable restrictor 46 in the line 45. The restrictor 46 ensures that some 20 seconds must elapse before the part 41 is coupled with the gear 39, the pump 10 thus being given sufficient time to ventilate the spaces near the drum 5 before the same starts up and the machine 1 starts up its winning movement.

The cylinder 43 can of course be replaced by an electric actuator energized by way of a time relay, again with the possibility that the drum 5 starts up later than the machine-driving motor 16 and thus ensures ventilation of the still stationary drum 5.

Claims (6)

1. A drum shearer-loader machine for underground mining, having shearing drums which are to be ventilated near their face-side end face, the machine having at least one liquid pump which derives its drive motion from the machine-driving motor which will supply pressurised liquid to injection nozzles producing the ventilation air flow, and incorporating a clutch which disconnects the shearing drum from its driving motor when the machine is stationary and which, in response to energization of the machine, produces, but only after a delay, the driving connection between the motor and the shearing drum.

2. A machine according to claim 1, wherein the clutch has a disengaging or release spring and an actuating cylinder for engaging the clutch and energisable by the pressure of the liquid pump or by the pressure of a lubricant pump, the pressurised liquid being supplied to the actuating cylinder by way of an adjustable restrictor.

3. A machine according to claim 1, wherein the clutch has an electrical actuating device which engages it against the force of the release spring and which receives its driving power by way of a time relay actuated upon energization of the machine.

4. A machine according to claim 1 and incorporating a liquid pump operating in both directions of rotation, the lutch being a freewheel clutch which provides the driving connection between the shearing drum nd the drum-driving motor means being provided such that, upon energization of the machine, the drum-driving motor rotates initially for a predetermined period in a first direction which does not allow the freewheel clutch to drive the shearing drum, and then rotates, but only after the motor has come to a standstill in the second direction enabling the freewheel clutch to transmit the drive to the shearing drum.

5. A machine according to claim 4, wherein said means comprises a reversing contactor whose two power contactors connect the machine-driving motor to the power supply mains seriatim and ar so operable seriatim by means of a time relay that upon energization of the machine the motor runs initially in said first direction of rotation and subsequently, but only after the dropping of the corresponding power contactor, in said second direction, after a period long enough for the motor to come to a standstill whereupon the other power contac tor is actuated.

6. A drum shearer loader machine of a kind substantially as herein decribed with reference to the accompanying drawings.