Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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1 BACKGROUND OF THE INVENTION
2 Field of the Invention
3 This invention relates to improvements in rcck-breaking
4 apparatus of the general type described in Australian patent
specification no. AU-B-27994/77 (522890).
6 Description of the Prior Art
7 Rock breaking apparatus of the type described in AU-B-
8 27994/77 includes a rock-breaking tool, a tool housing
9 having a bore therethrough, in which the tool body is
mounted for limited movement axial to the bore, a weight
11 designed to fall under the influence of gravity to impart an
12 impulse to said tool, and means to raise the weight.
13 Very large forces are generated~~in the use of said
14 apparatus. They are often sufficient to destroy the upper
lS collar on the tool body as it is driven against the upper
16 edge of the bore, which collar serves to limit downward
17 movement of the tool. This means that the tool must be
18 replaced, which is an expensive and time-consuming
19 operation. In the specification of Australian patent
specification no. AU-B-90861/82 (536689), there is suggested
21 a complex arrangement for cushioning the effect on the
22 apparatus as a whole of the force applied to the tool, by
23 providing a resiliently-mounted telescopic member at the
24 lower end of a guide column, through which the weight falls.
However, the specification does not address the problem of
26 the effect of the force on the tool per se.
27 Brief Summar~ of the Invention
28 It is an object of this invention to provide an
29 effective improved rock-breaking apparatus, which will
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over~ome 8~ lo~ 30~ 0~ the ti~adv~nt~ges of ~h~ prlor
~rt.
The invention provides an apparatus for breaking rocks, said
apparatus including a guide column, said guide column having a base
end and a peripheral wall inward of said base end, a tool at said
base, said tool being adapted for limited movement in the direction
of the axis of said guide column, a weight movable within said
guide column and adapted to fall under the influence of gravity to
strike the tool at said base end, the improvement comprising shock-
absorbing material provided at said base end, said shock-absorbing
material being located within said peripheral wall in the path of
fall of the weight and including an upper impact surface for impact
of the falling weight, said peripheral wall defining a cross-
sectional area, said material occupying a cross-sectional area less
than that defined by said wall, said material being adapted to
absorb direct impact of said weight thereon, at least partly by
deforming into the greater cross-sectional area of-said-peripheral
wall to minimize the effect of the impact of said weight generally
on said apparatus while enabling force to be transferred from said
~: 20 weight to said tool, said shock-absorbing material including an
aperture adapted to allow a portion of said tool to pass
:~ therethrough, said tool in a first position, at which it is at the
: upper limit of its limited movement, having a part thereof
extending above said upper surface, being adapted to be first
impacted by said weight, said weight subsequently impacting said
upper surface when said part of said tool is moved below said upper
surface as a result of the impact of said weight or said tool.
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The invention also provides apparatus for breaking
rocks, in which a weight is allowed to fall, under the
influence of gravity, in a guide column, to striXe a tool
or other article, said tool being mounted for limited
movement in an aperture in the base of said column,
characterized in that said tool has a recessed portion
which co-operates with a retaining pin located
substantially at right angles to the axis of said aperture.
The invention further provides apparatus for breaking
rocks, in which a weight may fall under the influence of
gravity to strike a tool or other article, characterized
by operating means for operating said apparatus, including
means for raising a weight, means for holding a weight in
one of a number of positions and means for allowing said
weight to fall.
The invention also provides apparatus for breaking
rocks in which a weight may fall under the influence of
gravity in a guide column to strike a tool, characterized
by tool and/weight sensing means located on or near said
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1 column.
2 Brief Description of the Drawings
3 Figure 1 is a front elevation of rock-breaking
4 apparatus according to the invention;
Figure 2 is a plan view of the lower end of the
6 apparatus of Figure l;
7 Figure 3 is a vertical cross-section along the lines
8 3-3 of Figure 2;
9 Figure 4 is a circuit diagram of the hydraulic system
used in the apparatus of Figure l;
11 Figures 5 to 7 are diagrams similar to that of Figure
12 4, showing different phases of the operation of the system;
13 and
14 Flgure 8 is an electrical circuit diagram concer-ning
the operation of proximity switches.
16 Detailed Description _ the Preferred Embodiment(s)
17 The rock-breaking apparatus is of the general type
18 illustrated in Figure 1 of Australian patent specification
19 no. AU-B-27994/77 (522890).
The apparatus 10 of Figure 1 includes a lower end 110,
:~ 21 an embodiment of which will be described in detail
` 22 hereinafter, a guide column 112, a weight 12 located for
23 movement within
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in plate 118. It is designed to accommodate a pin 144,
which in use co-operates with recess 140 to limit the axial
movement of tool 134 in bore 132.
The pin 144 is designed, as stated, to limit the
axial movement of tool 134 in bore 132, but also serves to
enable the tool 137 to be removed therefrom, without having
a split-plate arrangement such as that of the prior art.
Many alternative forms of location and securement of pin 144
in the aperture 142 may be utilised; the pin may be slightly
tapered to allow it to be hammered into place, but to also
allow it to be easily removed upon the application of a
reverse impulse. A circlip may be used to secure this pin
also.
It may be considered to have two pins and associated
recesses, one on either side (as viewed in Fig. 3) of tool
134. This would provide a balancing effect, although one
would have to be satisfied that the double reduction in
thickness of the.tool body would not reduce the strength
thereof.
Located within guide column 112 is an annulus ~46 of
polyurethane, or any other suitable material, such as a
relatively dense plastics or elastomeric material capable of
deformation, but with a 'memory' which allows it to return
to its original shape.after deformation.
In use, the lower end 110 operates as follows.
To break a rock, lower end would.normally be posi-
tioned with the working end 138 of tooL 134 in contact with
the rock_ The tool would then be in the position shown in
Fig. 3.
The weight (not shown) would then be ~llowed to fall
under the influence of gravity, to.strike the top of the
tool. 134, to propel. it downwards to break the rock. It can
be seen that the top of tool 134 protrudes above annulus 146,
: so that initially the force of .the weight is taken fully by
: 35 the tool 134. When the weight reaches the top of annulus
146, the annulus also absorbs.some of the force, and.serves
as a cushioning member, allowing itself to be deformed s~lch
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that (as viewed in Fig. 2) the material of the annulus can
move into the corners 148 of the guide column 112, which
corners are normally unoccupied by material. The further
the weight travels into the annulus 134, the more is the
deceleration effect, and eventually the weight will stop,
before it strikes plate 118, and before it forces the upper
shoulder of recess 140 into heavy rontact with pin 144.
When the weight is raised, the annulus will return to its
original shape, ready for the next impact.
Fig. 4 is a circuit diagram of an hydraulic system
which may be used to operate the apparatus of Fig. 1. The
following components shown in Fig. 1 also appear in Fig. 4;
hydraulic motor 20, hydraulic clutch 24 and drum 16.
Gearbox 24 (mentioned in relation to Fig. 1) is also shown.
The system includes relief or check valves 200,202
which act to protect major components~ Flow-control valve
204 permits a flow of approximately 220 litres per minute
of fluid during the 'raise' mode (to be described herein-
after) and acts to divert excess flow back to the carrier/
hydraulic pump 212.
A two-way solenoid valve 206 allows all the flow
(fluid) to pass back to the carrier when signalled to do so
by proximity switch 26 (Fig. 1). This prevents the tool 134
(Figs. 2 and 3) striking the inside top of guide column 112
(Fig. 1) in the absence of an operator releasing the apparatus
from the 'raise' mode.
A pressure-reducing valve 208 allows the required
pressure to pass, allowing the activation valve 210 to
activate. The activation valve 210 activates hydraulic
clutch 22 with a pressure of approximately 420 p.s.i. (30
BAR) to allow clutch 22 to engage. Valve 210 also allows
the clutch 22 to disengage when the 'release' mode is selec-
ted by an operator or the like
Preferably, valves 200 to 210 inclusive are` 35 incorporated in a valve bank; that is, the valves are located
in proximity to one another in a single housing, and the
hydraulic conduits are plumbed to the valves in the valve
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bank. Such an arrangement is more efficient for mainten-
ance. However, the valves may be located in other
appropriate ways.
The hydraulic motor 20 is a high speed, high torque
motor necessary for high performance of a fast cycle, such
as the 'raise' mode of the apparatus 10.
The hydraulic clutch 22 is designed to engage
hydraulically and disengage under spring pressure. When
engaging ('raise' mode) the hydraulic pressure couples the
clutch input shaft (not shown) to the clutch output shaft
(not shown) to allow torque to be transmitted through the
clutch 22 to the gearbox 24. When the 'release' mode is
selected the activation valve 210 allows the hydraulic
pressures to fall to zero, thus allowing the clutch 22 to
spring-disengage to allow the winch drum 16 to freely rotate.
A minor modification could be made for a clutch with an
'hydraulic disengage, spring engage' mode of operation.
The function of the gearbox 24 is to reduce the
revolutions from the hydraulic motor to approximately 50
r.p.m.. The gearbox 24, being mounted strategically within
drum 16,allows maximum torque to be transmitted.
For operational reasons, it may be considered
preferable to locate the clutch 22 at the outside of the
clutch-motor-gearbox arrangement, so that one would have,
from the left in Fig. 1, clutch 22, motor~20, gearbox 24.
The system also has carrier 'tilt' or spool valves
214, and an optional six-port cross-over diversion valve 216.
Drain line 220 leads to carrier 212.
Reference is now made to Fig_ 5, which shows the
system with the 'raise' mode selected; the 'raise' mode is
used to bring hammer 12 to its maximum height in guide
column 112 (Fig. 1). The lines subject to hydraulic
pressure are hatched, and those subject to pressure once
proximity switch 26 (Fig_ 1) has been actuated are shown~as
broken line 218.
With the 'raise' mode selected, the carrier/
hydraulic pump 212 supplies fluid under pressure, which is
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allowed into the circuit by valve 214. Optional valve 216
may act to divert some fluid.
Flow-control valve 208 allows the required volume
of fluid therethrough, and the hydraulic motor 20 is
activated. The pressure-reducing valve 208 and the clutch
activation valve 210 operate to engage the clutch 24, which
in turn activates the drum 16. Drum 16 winds rope 14,
raising weight 12.
Normally, one would expect an operator to shut off
the 'raise' mode controls when the weight 14 reaches a useful
but safe height. However, if that is not done, the line 218
pressurization takes place, in that the position of hammer
14 activates proximity switch 26, which in turn operates
solenoid valve 206. The solenoid valve 206 opens,
preventing supply of fluid to motor 20, thus preventing
further raising of weight 14.
~ ig. 6 shows the circuit of hydraulic system in the
'hold' mode. Lines subject to tank pressure are shown
hatched, and lines subject to load pressure are denoted by
broken lines 222.
As can be seen, tank pressure fluid is locked
between components 200, 202, 210, 214 and 224. When the
controls for the 'hold' mode are selected, the weight/hammer
14 can be held at any point.
Finally, Fig. 7 shows the state of the system when
the 'release' mode is selected. Lines subject to pump
pressure are shown hatched. Broken line 226 denoted the
drain line to tank 220 at tank pressure, which is minimal.
Fluid is supplied by carrier 212 through valves 214
at (optionally) 26. The pressure relief valve 208 allows a
required pressure, and clutch activation valve 210 operates
to disengage the clutch 22. The gearbox 24 and drum 16 are
then free to rotate, which they do as weight 12 falls under
the influence of gravity to strike tool 134 (Figs. 2 and 3).
If, for some reason, the 'raise' mode is selected during the
free fall of weight 12, the pressure relief valve 202 which
operate to allow deceleration to occur, thus preventing damage
to the motor 20 and its components.
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In use, the apparatus 10 (which is preferably mounted ona vehicle or the like for easy transportation).is located
over an area of rock or the like to be broken, pxeferably
with the working surface 138 of tool 134 placed on the rock or
the like.
The operator then selects the 'raise' mode, which operates
as described herPinbefore to raise hammer 12. Once the weight
12 has reached a desirable height (which may be indicated by
some form o~ visual or other indication) the operator may
1~ select the 'hold' mode, and may then proceed to select the
'release' mode, or may go straight to the 'release' mode.
In the 'release' mode the hammer 12 falls to strike tool
134, driving it with an impulse into the rock or the like.
Fig. 8 is an electrical circuit diagram into which
the three proximity switches 26, 27 and 29 ~re wired. The
switches sense the presence or absence of the weight 12 or
the pin 144, and function, through relay 31 and solenoid 33,
to engage or disengage the hydraulics which raise weight 12.
The proximity switches are arranged so that switches
26, 29 are normally closed, in series, and switch 27 is
normally open in parallel. The switches activate when magnetic
contact is made with weight 12 or pin 144.
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Switch 26 goes to a closed mode when the weight 12
is sensed, near the top of guide column 112, and .his serves
to stop the raising of the weight 12. All is in readiness
for the release of the weight.
However, if at this stage pin 144 is not sensed by
switch 29, that is, if it is not in the position shown in
Fig. 1, but is in a lower (incorrect) position, the weight
will not be released because switch 29 will be open. Only
when the apparatus is correctly positioned will the top of
pin 144 be sensed by switch 29.
If pin 144 is sensed, the circuit will operate the
hydraulics to raise the weight 12. When weight 12 passes
switch 27 a first time, going up, it will be sensed, but
will not affect the continued raising of the weight. Only
when the weight 12 is sensed by switch 27 on the way down,
will the circuit operate to brake drum 16,-preventing over-
run of the cable 14 (and 'whiplash') and minimising the
impact on the base 110 of the apparatus 10.
It can be seen that this invention provides apparatus
for breaking rocks and the like, which is effective and safe
in its operation. It is clear that the essence of the
invention could be used in apparatus for other purposes,
such as pile driving.
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