GB2095721A - Underground mine haulage chain equipment - Google Patents

Abstract

Equipment is provided for maintaining the tension of a portion of a haulage chain 2 trailing behind a mining machine traversing along a longwall face within preselected limits. The equipment comprises a chain guide arrangement (3) for guiding the chain extending along the longwall face towards ram means (4) secured to the end of the chain to apply tension to the chain. Sensor means (9) are provided to sense the tension existing in the portion of the chain extending between the machine and the chain guide, the sensor means being adapted to derive a signal when the sensed chain tension reaches a preselected relatively high value. The derived signal is fed to control means (6) for the ram which thereby is actuated to reduce the chain tension. <IMAGE>

Description

SPECIFICATION Underground mine haulage chain equipment This invention relates to underground mine haulage chain equipment for use with substantially stationary haulage chains which extend along longwall faces and along which mining machines haul themselves repeatedly to and fro.

In particular the present invention relates to equipment for mounting at one end of a haulage chain for controlling the maximum tension in an adjacent portion of the chain when the associated machine is traversing away from the equipment.

A form of prior known haulage chain equipment comprises a hydraulic ram secured to the associated end of the haulage chain and pressurised to apply a desired maximum pull on the chain. In one common arrangement in order to allow the machine to travel up to the end boundary of the longwall face the haulage chain extending along the face is passed around a chain guide or spcokets mounted adjacent to the end boundary of the face before reaching the hydraulic ram. Unfortunately, in use as the mining machine traverses repeatedly to and fro the resistance to chain movement around the guide is unpredictable and frequently, due to frictional losses and a build up of material packing the guide or sprockets the resistance to chain movement can tend to become excessive.Thus, when the mining machine is moving away from the installed equipment the tension in the trailing portion of the chain extending between the machine and the chain guide can be excessively large and potentially dangerous before the tension existing in the portion of the chain extending between the chain guide and the hydraulic ram becomes sufficiently large to cause the ram to relieve and reduce the chain tension.

An object of the present invention is to provide improved haulage chain equipment which tends to overcome or reduce the above mentioned problem.

According to the present invention underground mine haulage chain equipment for use with a substantially stationary haulage chain which, in use, extends along a longwall face and along which a mining machine hauls itself repeatedly to and fro, comprises a chain guide arrangement for directing the chain extending in a direction along the longwall face towards means securable to one effective end of the haulage chain, said means being adapted to apply tension to the adjacent portion of the chain when, in use, the mining machine is hauling itself along the haulage chain in a direction away from the equipment, and sensor means for sensing the chain tension existing in the portion of the chain extending between the machine and guide arrangement and for deriving a signal when the sensed chain tension reaches a preselected relatively high value, the derived signal being fed to the means for applying tension to the chain which thereby is controlled to substantially prevent the sensed chain tension exceeding the preselected relatively high value.

Preferably, the means for applying tension to the chain comprises a hydraulic ram.

Preferably, the means for applying tension to the chain comprises fluid pressure control means for the hydraulic ram.

Conveniently, the sensor means comprises a reaction member for abutment by the tensioned chain.

The present invention also provides a haulage chain installation comprising equipment as defined above provided at both ends of the haulage chain, respectively.

By way of example only, one embodiment of the present invention will be described with reference to the accompanying drawings, in which Figure 1 is a diagrammatic side view of one end of a haulage chain installation on a longwall face in an underground mine; and Figure 2 is a sectional view of a detail of Figure 1 drawn on an enlarged scale.

Figure 1 shows one end of an armoured face conveyor 1 installed along a longwall face in a mineral seam of an underground mine. The conveyor comprises a plurality of pans articulatedly connected end to end to define a conveying deck along which at least one effectively endless driven chain is hauled, the chain having flight bars for urging cut mineral loaded on to the conveyor to be moved along the deck. A substantially stationary haulage chain 2 extends along the length of the face and is anchored at its ends of sets of haulage chain equipment, respectively. Each set of equipment comprises a guide arrangement 3 constituted by a curved plate for deflecting the chain extending in the direction of the longwall face towards a hydraulic ram 4, 5 which is fixedly mounted on to the conveyor head frame and which is adapted to apply tension to the chain.As shown in the Figure one end of the piston rod 5 is secured to the effective end of the chain.

Pressure fluid control means 6 are provided for controlling the supply of pressure fluid to and from the ram to control the operational mode of the ram. The ram is provided with feed lines 7 and 8 which connect the ram with a suitable supply as, for example, the hydraulic feed circuit for hydraulically powered roof supports (not shown) installed along the longwall face. Alternatively the ram may be fed from a hydraulic power pack provided for the chain tensioning equipment.

The equipment also comprises sensor means 9 for sensing the tension in the portion of the haulage chain extending between the chain guide arrangement 3 and the mining machine (not shown) when the machine is hauling itself in a direction away from the guide arrangement 3. The sensor means 9 is adapted to derive a signal when a preselected chain tension is sensed, the signal being fed to the control means 8 which thereby activates the ram into a relatively extended mode to reduce the chain tension. Thus with the machine moving away from the equipment of Figure 1, the tension in the portion of the chain extending between the chain guide 3 and the machine is maintained below a preselected value irrespective of the resistance to chain movement around the guide 3.

The details of one embodiment of the sensor means 9 are shown in Figure 2, the sensor means comprising a deflectable diaphragm 10 secured to the housing 11 of the conveyor head frame by bolts (not shown) and a seal (not shown) preventing ingress of dirt into the housing. The diaphragm is provided with a reaction pad 24 mounted for abutment by the chain. As seen in Figure 1 the chain passes over the pad before it is directed towards the chain guide 3. The sensor also comprises a body 12 mounted with respect to the housing 11 via a present position adjustment mechanism including two adjustment screws 13 and two guide slots 14.

A spring 1 5 acts between the diaphragm 10 and the body 12 tending to resist deflection of the diaphragm under the action of the tensioned haulage chain. A further spring 1 6 abutting a cap 1 7 tends to urge a plunger 18 towards the diaphragm such that upon the diaphragm being deflected a preselected amount it will abut the plunger. Upon further movement of the diaphragm the plunger 1 8 is urged to move against a spring loading with a shoulder 25 provided on the plunger disengaging a valve seating 26 provided on the member 12 to interconnect inlet passage 20 with outlet passage 21. The interconnection of the passages 20 and 21 constitutes a signal being derived which is fed to the ram control means 6 via outlet passage 21 and lines (not shown).The flow of pressure fluid along passage 21 tending to cause the ram to extend thereby tending to reduce the chain tension. Upon the chain tension being reduced to the desired level the amount of diaphragm deflection is reduced such that the plunger is disengaged and allows to move under its spring loading until the shoulder 25 once again abuts the valve seating to close the valve isolating passage 20 and 21.Thus further extension of the ram is prevented.

The annulus side of the ram is maintained at full working pressure so that if the main tension should tend to fall below a preselected value determined by the preset full working pressure, the ram will tend to contract until the chain tension once again reaches the preselected value.

Thus, it will be appreciated that when the mining machine is traversing along the longwall face in a direction away from the equipment shown in Figures 1 and 2, the equipment tends to maintain the chain tension in the portion of the chain extending between the machine and the chain guide 3 within preselected limits.

When the machine is traversing along the face in a direction towards the equipment the chain tension tends to be so great that the ram is urged to a solid mode with the piston abutting a stop formation.

From the above description it will be seen that with the mining machine traversing away from the equipment, the present invention provides equipment for sensing the portion of the haulage chain which extends along the longwall face within desired preselected limits substantially irrespective of the resistance to chain movement around the chain guide 3.

In a typical installation a set of equipment similar to that shown in Figures 1 and 2 will be installed at each end of the longwall face.

In other embodiments of the invention the sensor means of Figure 2 is replaced by sensor means comprising a strain gauge or a pressure sensitive means.

In other embodiments of the invention the means for applying tension to the chain comprisea a drive sprocket or other suitable means.

Claims (6)

1. Underground mine haulage chain equipment for use with a substantially stationary haulage chain which, in use, extends along a longwall face and along which a mining machine hauls itself repeatedly to and fro, comprising a chain guide arrangement for directing the chain extending in a direction along the longwall face towards means securable to one effective end of the haulage chain, said means being adapted to apply tension to the adjacent portion of the chain when, in use, the mining machine is hauling itself along the haulage chain in a direction away from the equipment, and sensor means for sensing the chain tension existing in the portion of the chain extending between the machine and guide arrangement and for deriving a signal when the sensed chain tension reaches a preselected relatively high value, the derived signal being fed to the means for applying tension to the chain which thereby is controlled to substantially prevent the sensed chain tension exceeding the preselected relatively high value.

2. Equipment as claimed in claim 1, in which the means for applying tension to the chain comprises a hydraulic ram.

3. Equipment as claimed in claim 2, in which the means for applying tension to the chain comprises fluid pressure control means for the hydraulic ram.

4. Equipment as claimed in claim 1, 2 or 3, in which the sensor means comprises a reaction member for abutment by the tensioned chain.

5. Underground mine haulage chain equipment substantially as described herein and substantially as shown in Figure 1 and/or Figure 2 of the accompanying drawings.

6. A haulage chain installation comprising at least one set of equipment as claimed in any one of the preceding claims.