High pressure water assisted mining and tunnelling machine

An accessory for a mining or tunnelling machine comprising a cutting drum is disclosed. The accessory comprises a radial piston pump mountable in the cutting drum, the pump comprising a plurality of piston and cylinder assemblies adapted to supply water under pressure to a nozzle or nozzles mounted in the periphery of the drum.

FIELD OF THE INVENTION 
This invention relates to mining and tunnelling machines. More 
particularly, the invention relates to machines adapted for cutting rock, 
coal, ore and the like, utilising rotating cutting means such as drums 
armed with picks, such as longwall shearers, continuous miners, 
roadheaders and the like, and to a method of cutting rock, coal, ore and 
the like, utilising such rotating drums. 
BACKGROUND OF THE INVENTION 
It has been found by others that the operation of the machines referred to 
in the opening paragraph can be significantly improved with the aid of 
high pressure water sprayed on to the material to be cut. Not only does 
the high pressure water enhance the cutting action of the picks, but it 
also serves to improve the environment by reducing the amount of dust that 
is liberated into the atmosphere during cutting. Water pressures of up to 
60 bars have been found by others to yield good results. However, recent 
developments in the art indicate that pressures of between 200 and 2000 
bars produce even better results. At pressures of around 1500 bars it has 
been found that pick life can be increased by a factor of about 10 to 20. 
To provide water to the rotating drums of such machines at an intermediate 
pressure of 10 to 60 bars does not create serious technical problems. 
Systems are in operation in which water at such intermediate pressures is 
supplied to the rotating drum by means of booster pumps either mounted on 
board the cutting machine or at some distance away therefrom. In the 
context of conventional mining machines using high pressure water, on 
board booster pumps are either located on the chassis of the machines or 
are built into ranging arms adapted to raise and lower the cutting drum. 
However, to supply water to the cutting drum at high pressures, for 
instance pressures of more than 200 bars, creates a serious technical 
problem. The further the pump is located away from the cutting drum, the 
longer the length of hoses or pipes that have to be provided to convey the 
water to the cutting drum and therefore the more vulnerable the hoses 
become to damage from the environment, such as falling rocks and the like. 
It will also be appreciated that the higher the pressure of the water, the 
more damage could be done to both operating personnel and equipment, by 
water escaping from burst or leaking hoses. Furthermore, since the cutting 
drum rotates during use, and the nozzles thereon require a high pressure 
only during a part of each revolution of the drum, expensive water swivels 
and sequence valves are required for such systems. 
Booster pumps located in the ranging arms of such machines offer the 
advantage that they are protected from falling rocks and the like and are 
concealed from operating staff, but they are mechanically complicated and 
suffer from the disadvantage that any water leakage could contaminate 
lubrication oil usually present in such ranging arms as such arms usually 
also house a gearbox or other drive means for driving the cutting drum. 
Furthermore, the maintenance of such pumps is complicated because of their 
location in the ranging arm and the need for expensive water swivels and 
sequence valves still exists. 
OBJECTS AND SUMMARY OF THE INVENTION 
It is an object of the present invention to provide an accessory for a 
mining machine which is adapted to supply high pressure water to nozzles 
located on the cutting means, e.g. drum, and is less expensive to 
manufacture and operate than conventional high pressure water assisted 
cutting systems. 
According to one aspect of the present invention, there is provided an 
accessory for a mining or tunnelling machine comprising a rotary cutting 
means, drum, or the like cutting tool, the accessory including a radial 
piston pump comprising a plurality of piston and cylinder assemblies, each 
piston and cylinder assembly being adapted to supply water under pressure 
to a nozzle adapted to direct the water onto material to be cut by the 
machine, the radial piston pump being mountable in the rotary cutting 
means, more particularly coaxially therein. 
The accessory may comprise more than one pump, and where it comprises more 
than one pump, the pumps may be arranged so that one pump is axially 
spaced from the other. Alternatively or additionally, the or each pump may 
comprise two or more banks of piston and cylinder assemblies. 
The number of piston and cylinder assemblies of the or each pump could vary 
depending for instance on the number of nozzles that have to be supplied 
with high pressure water, the dimensions of the drum or the like, and the 
dimensions of each piston and cylinder assembly. 
As will be appreciated, the smaller the number of piston and cylinder 
assemblies, the more uneven the pressure will be that is supplied to the 
nozzles located in the operating area of the rotary means, e.g. periphery 
of the drum. Conversely, the larger the number of pistons, the more 
constant the pressure would become, but at the same time, the more prone 
the accessory would become to mechanical problems. So as to alleviate this 
problem, the water may be supplied via a manifold to each or at least some 
of the nozzles. 
The required cutting speed of the drum, and hence, the speed at which the 
or each pump will rotate, depends upon the type of coal or other material 
that is to be cut by the machine. It has been found by the applicant, 
however, that for coal using a drum of 1.8 m diameter, a speed of from 30 
to 50 rpm is suitable, preferably from about 33 rpm to about 48 rpm. For 
other applications, different drum diameters and rotational speeds may be 
utilised. 
It will be appreciated that, by increasing the speed of the cutting drum 
during use thereof, higher water pressures and flow rates could be 
obtained. 
Low pressure water may be supplied to the pump via a low pressure swivel 
which may be mounted on the goaf side of the drum shaft and connected to a 
supply of low pressure water. The low pressure swivel may be connected to 
each cylinder via passage means coaxial with the drum shaft, e.g. a hollow 
rod extending through a bore of the shaft which is hollow as well. One end 
of the rod may be connected to the low pressure water swivel and the other 
end may have one or more passages, the or each passage interconnecting a 
cylinder of the pump with the hollow rod. 
One end of the rod may be adapted to be held in any one of a plurality of 
substantially fixed positions. The other end of the rod may comprise a cam 
adapted to cause the pistons of the pumps to reciprocate when the pump is 
rotated. 
The cam may be in the form of a cylindrical formation eccentrically mounted 
on the rod. 
Water flow rates of from 10 to 80, preferably about 40 liters per drum per 
minute have been found to yield satisfactory results when the accessory is 
used with presently available longwall shearers. It will be appreciated 
that the gross flow rate per drum has to be divided by the number of 
piston and cylinder assemblies in order to obtain a desired flow rate per 
piston and cylinder assembly. It will also be appreciated that the higher 
the flow rate of water, the less dust will be liberated during cutting, 
but then the more water would have to be disposed of at the face and this 
may present problems in underground collieries. 
The preferred accessory according to the invention is adapted for easy 
retrofitting to existing mining and tunneling machines. 
The invention also extends to a method of mining or tunnelling, including 
the step of providing water at high pressure to a nozzle or nozzles 
directed at rock material being excavated by a rotary cutting means, such 
as a cutting drum forming part of a mining machine, the high pressure 
water being provided by means of a radial piston pump mounted in the 
rotary cutting means of the said machine. 
The invention also extends to mining and tunnelling machines equipped with 
the accessory according to the invention.

DETAILED DESCRIPTION OF THE DRAWINGS 
Referring to FIG. 1, reference numeral 10 generally indicates a cutting 
drum of a longwall shearer (shown in FIG. 5). The cutting drum 10 is 
mounted on the end of a ranging arm 12 of the longwall shearer and drive 
means (not shown) is provided in the ranging arm 12 for driving the 
cutting drum 10. The cutting drum 10 is mounted such that it can rotate 
about the axis 14. A radial piston pump 16 is mounted coaxially in an 
outwardly facing cavity 18 of the cutting drum 10 and is protected from 
the exterior by means of a lid 20. Lugs 22 (see FIG. 2) are provided on 
the shell 24 of the pump 16 for facilitating the mounting thereof in the 
cavity 18. Although lugs 22 are used in the embodiments shown in the 
drawings, for mounting the pump 16, it will be appreciated by those 
skilled in the art that alternative means of mounting may be employed 
depending upon the geometry of the cutting drum of a particular longwall 
shearer. 
As can be seen in FIGS. 2 and 3, the pump 16 comprises ten radially 
orientated piston and cylinder assemblies 26. A hollow rod 28 which 
extends axially through the drum 10, is provided, one end 30 thereof being 
adapted to be held in one of two positions 180.degree. apart from each 
other (details of which are shown in FIG. 6). A cam 32 is provided on the 
other end of the rod 28, the cam 32 being of cylindrical or spherical 
shape and being mounted eccentrically with regard to the axis of the rod 
28. 
The rod 28 extends through a hollow shaft 34 interconnecting the drive 
means in the ranging arm 12 with the cutting drum 10. An annular space 
(not shown) is provided between the interior surface of the shaft 34 and 
the rod 28. Low pressure water is fed to the pump 16 through a hose 36 
coupled to a low pressure swivel 38 which in turn communicates with the 
cylinders of the pump 16 through the bore 37 of the rod 28 and passages 39 
in the housing of the pump 16 communicating with the bore of the rod 28. 
High pressure water discharged from the cylinders is fed to nozzles 40 
(see FIG. 3), by means of tubes 42 which may be made of stainless steel, 
the nozzles 40 being provided in the vicinity of picks 44 projecting from 
the shell 45 of the cutting drum 10. A circumferentially extending annular 
manifold 46, which may be segmented, is provided to be in communication 
with the discharge of each piston and cylinder assembly through a combined 
inlet/outlet valve (not shown). 
Each piston and cylinder assembly 26 comprises a cylinder 26.1 and a piston 
26.2 provided with a formation 26.3 adapted to engage with the cam 32. 
FIG. 4 shows a conventional long wall shearer 50 fitted with an accessory 
in accordance with the invention. The shearer 50 comprises two cutting 
drums 10 and two ranging arms 12. The shearer 50 is capable of cutting 
either in the direction as indicated by the arrows 52 or in the direction 
as indicated by the arrows 54. 
In FIG. 5 is shown a partly sectionalized side elevation of an accessory 
comprising a rotary piston pump 16' having two banks of piston and 
cylinder assemblies 26. This embodiment of the invention provides a 
solution where it is desirable for each nozzle to be connected to a piston 
and cylinder assembly and the number of piston and cylinder assemblies 
thus required exceeds the number which could be accommodated in the 
diameter of the cavity 18. 
FIG. 6 shows a circular plate 56 rigidly connected to the rod 28. The plate 
56 is provided with holes 56.1, 56.2 through which it is removably 
connectable by means of bolts (not shown) to the end 12.1 of the ranging 
arm 12. 
In use, the cutting drum 10 of a longwall shearer 50 is positioned so that 
the picks 44 engage with the material to be cut. The drum 10 is then 
driven through the drive means located in the ranging arm 12. The pump 16 
rotates with the cutting drum 10, whilst the rod 28 is held stationary by 
means of the plate 56 in either of the two aforementioned positions. 
Rotation of the pump 16 about the cam 32 which is held stationary by the 
rod 28, causes the pistons 26.2 to reciprocate in the cylinders 26.1, with 
the result that low pressure water supplied to the cylinders through the 
hose 36, swivel 38 and bore of the rod 28, is pressurized and discharged 
to the nozzles 40 via the combined inlet/outlet valves, the manifold 46 
and the tubes 42. The water discharged by the nozzles 40 is directed onto 
the material being cut by the picks 44, thereby assisting the cutting 
action of the picks 44 and suppressing dust caused by the cutting action. 
It will be appreciated that each piston and cylinder assembly 26 supplies 
high pressure water only during one half of a drum revolution, whilst for 
the balance of each revolution low pressure water flows to such piston and 
cylinder assembly 26. The position of the rod 28 is selected such as to 
ensure that water is discharged from the nozzles 40 located in the 
vicinity of picks 44 being in contact with the material to be cut. Under 
circumstances where the shearer 50 is used to cut in the direction 52, the 
rod 28 will be in one position and when the shearer 50 is used to cut in 
the opposite direction 54, the rod 28 is rotated through 180.degree. to 
the other position in which it is adapted to be held fixed so that the 
nozzles 40 would discharge water on the opposite side of the drum 10. 
It will be understood that, although the invention has been exemplified 
particularly with reference to rotary cutting drums whereof the cutting 
action is essentially normal to the drum periphery, armed with cutting 
bits in the form of picks, the invention may also be applied to rotary 
cutting means whereof the cutting action is in an axial direction as is 
the case with some narrow seam coal or rock cutters, rock borers, raise 
borers, tunnel borers, drive borers and the like. 
Also the invention is not limited to use with rotary cutting means armed 
with picks. Depending on the type of rock to be cut, the high pressure 
water jets may coact with any compatible rock cutting means known in the 
art, including roller bits, disc bits, hard rock cutting teeth, optionally 
vibration assisted.