Note: Descriptions are shown in the official language in which they were submitted.
This invention relates to an appar~tus for digging
stones and rocks, soil and sand, minerals and the like (as will
! hereinafter ~e called merely soil and rock for simplicity), and
more particularly to a transport apparatus for use in digging
soil and rock by the use of a novel combination of a drayline
with haulage or transport system such as conveyor means and
hopper means.
This application is a divisional applicationof copend-
ing application No. 307,320 filed July 13, 1978.
In recent years there has been a need for high-
production and hiyh efficiency excavation methods in large
scale land creating works, foreshore reclamation works,
surface coal mining works on coal seams having thick
overburden, or the like. One conventional method of
digging soil and rock in the open air was to effect
excavation by a shovel loader and carrying away the
excavated material by trucks. Another method was to effect
excavation by a bucket wheel excavator and haul the
excavated material on a belt conveyor. Any of these prior
art methods has been unsatisfactoxy with respect to the
high capacity and efficiency when they were applied to large-
scale works~ Both the shovel loader and the bucket wheel
excavator were inherently limited in size of their shovel or
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bucket becau6e of their structu~e, hence they had a limited
capacity. In addition they were particularly unsuikable
for handling large masses of soil and rock, so that
many manhours were required for blasting operations to
prevent such large masses from being produced or for
boulder blasting operations when great lumps were
produced. The aforesaid former method is undesirable
especially in excavating places involving bumpy roads because
trucks are subject to severe damages.
Digging by the use of a high capacity dragline
is known in a vast amount of rock removing work on
overlying strata (overburden) above a coal seam as in a
strip coal mining~ This method provides a very high
eEficiency and large capacity operation in that the
overlying rock as dug by the dragline are dumped and
piled directly on the gob or waste area without using
any intermediate transport means. However, in mining
multiple coal s-trata having more than two coal seams it
may be impossible to carry out the mining operation
on the second and lower coal seams when the total thickness
of the overlying rock layers exceeas the capacity of a
dragline. Practically, therefore, it has been heretofore
a usual practice to mine only the first uppermost coal
seam even in the case of a multiple coal strata,or at
most to dig out the upper layer of rock overlying the first
:
- coal seam by a power shovel, haul the excavated material
to anothe~ place by trucks and then use draglines to
dig the overburden of the second coal seam.
Even~in the case of a single coal stratum, if
there is a large"thickness of overburden, there will be
a correspondingly increased quantity of waste produced,
so that an increased proportion of the waste which has
once been dumped at one place must be again transferred
to another distant place, resulting in decreasing the
efficiency in operation. Furthermore, the boom of a dragline
must be swung through an arc of more than 90 up to approximately
180 in operation in order to dump the waste as far as
possible, resul~ing in extending the time required per cycle
of the bucket, hence a decreased efficieny. ~his is due
to the dragline's characteristics that despite its great
digging capacity the transporting distance is limited
to the length of its boom or at most the order of
100 m.
Belt conveyors are known as a large capacity and
high efficiency haulage means. Shiftable conveyors capable '
of lateral movements are particularly suitable for use at
a mining area where mobility of the transport means is
required. Mining operation is composed primarily of
digging and transporting operations. In the past, however,
there has been no mining process employed involving a
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combination of a dragline as described which is a large
capacity and high efficiency excavator and a b~lt conveyor
which is likew~se a high capacity and high efficiency
transporter. 4ne of the reasons is attributed to the
dragline's cha~acteristics. That is, since the dragline
swings its boom to move its vast bucket filled with
the excavated soil and rock (as will hereinafter
be referred to as excavated or aug material), the
dragline is best suited to dump the excavated material
while scattering it over some extent of area. But it has
difficulties in dumping the excavated material onto a
particular small target such as a hopper or the deck of
a truck. If this is to be done, it would take much time
to position ~he dragline itself such that the bucket may
be brought to a position directly above the hopper. It
would also take a lot of time to bring the bucket to a
halt just above the hopper in each cyclic operation between
scraping and dumping actions by the bucket, resulting in
an extended cycle time of the bucket and a decrease in
efficiency. The dragline cculd not thus exhibit its
inherent special performance. ConVersely, if the
bucket were allowed to dump the material over a considerable
extent of region, the hopper should be an enormous one in
. size enough to receive the moving bucket. Even though
it were made possible to hold the bucket size down to a
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certain extent by spending much time in controlliny the
movement of the bucket as described above, the bucket would
still be of a c~nsiderable size and should be capable of
movement as the dragline is moved around. Such movable
hoppers have not heretofore been proposed.
Another reason that the combination of the
dragline and belt conveyor has not been used lies in
the belt conveyor. Materials dug often contain big
masses of rock or stone. While the dragline can scrape
up such big lumps by its vast bucket, ordinary hoppers or -~
belt conveyors cannot accommodate or handle big lumps.
For the foregoing reasons any mining system utilizing a
combination of draglines and belt conveyors has not been
conceived of in the past.
In said copending application there is provided a
method of excavating stones and rocks, earth and sand, minerals
and the like by the use of a noval combination of the dragline
and transport means.
Also in said copending application there is provided
a method of excavating and carrying away stones and rocks,
earth and sand, minerals, etc. in an efficient manner.
Thus in said copending application there is provided a
method of digging and transporting soil and sand, rocks
and stones, minerals or the like by the use of a dragline
including a bucket means for digging and carrying said
soil, rocks, minërals, or the like, a boom means suspending
for swinging movement therewith, a bucket control means
for controlling said bucket means, and a boom control
means for controlling the swinging movement of said boom
means is provided which method comprises the steps of:
(a) fixing a hopper means at a predetermined
location straddling a conveyor means for transporting
the material dug, said hopper means being shiftable along
tXe conveyor means and adapted to receive the dug
material as carried in the bucket means by said dragline
and load the material onto the conveyor means;
(b) positioning said dragline at such a
location that the dug material in the bucket means may
be dumped from right above said hopper means; ~ ;
(c) digging soil, rock, minerals, etc. and
loading the material dug onto said hopper means by
operating said bucket control means and boom control means
at said location, and performing such digging and loading
operations in a like manner with said boom means positioned
at its various swin~ positions, as required;
(d) thereafter shifting said hopper means by
a certain distance along said conveyor means and fixing
it in place;
(e~ ~carrying out the steps ~b~ and (c) î and
(f) ~repeating the steps (d) and (e), as required.
The present invention provides
an apparatus for transporting soil and sand, rocks and
stones, minerals or the like dug by a dragline is provided
which apparatus includes a hopper means straddling a
conveyor means for transferring the material dug, said
hopper means comprising a pair of opposed side walls
extending parallel to the longitudinal axis of said conveyor
means, the walls defining an upper opening for receiving
the material dug and sloping downwardly inwardly toward
the conveyor means to form therebetween a lower discharge
opening through which the dug material is deposited onto
the conveyor means; a pair of opposed end walls extending
transversely to the length o the conveyor means;
a sieve means extending across said upper opening for
separating relatively large masses from said dug material;
support means for supporting at least said side walls; and
mobile means attached to said support means for making
said hopper means movable along the conveyor means.
According to still another aspect o~ the invention
a transporting apparatus of the type described
is provided which further includes a dug material receiving
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means comprising a receiving plate inclined in a di.rection
opposite the direction of inclination o said hopper means,
a support means'for supporting said receiving plate, and
mobile means attached to said support means movable along
said conveyor means, said receiving plate being disposed
above said hopper means.
According to still another aspect of the invenkion
a transporting apparatus of the type described is provided
which further includes a second ConVeyOr means positioned
shiftably along said sieve means and arranged to receive
and transport those large masses of the dug material
separated by said sieve means, a crusher means positioned
shiftably along said hopper means and arranged to receive
the large masses from the second conveyor means and break
them to fragments, and a third conveyor means positioned
movably along said hopper means and arranged to carry
said broken fragments from the crusher means back to said
first conveyor means.
The present invention will be further described
with reference to the accompanying drawings in which:
Fig. 1 is a side elevation of a walkiny dragline;
Fig. 2 is a top plan vi~w illustrating an entire
a~rangement in a mining area to which the mining system
according to the invention is applied;
Fig.'3 is a diagramatical view showing the positional
relation between the hopper and walking dragline;
Fig. 4 is a perspective view illustrating the
convèntional operation of the bucket of the dragline;
Fig. 5a and 5b are schematic views showing xequential
steps of operation of the walking dragline according to
the invention;
Fig. 6 is a side view showing the operation of
a bucket using an auxiliary rope according to the
invention;
Fig. 7a and 7b are schematic views showing
sequential steps of operation of the walking dragline
equipped with an auxiliary rope according to the invention;
Fig. 8 is a schematic view showing the
operational principle on which the dragline with an
auxiliary rope according ko the invention is driven;
Fig. 9 is a plan view illustrating the method
: 20 according to the invention of digging the over~urden of
each of three coal seams in a three-strata coal mine;
Fig. 10 is a sectional view taken on the line
A - A of Fig. 9;
Figs. 11 to 14 are side elevatisns, partly in
section of various forms of hopper means accsrding to
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"
the invention;
Fig. 15 is a front view of a wheel mounted
on a supporting, frame of the hopper; and
Fig. 16 is a side view of the wheel in Fig. 15.
PREFERRED EMBODIMENTS OF THE INVENTION:
.. . .
Referring to Fig. 1, a walking dragline 1 is shown
comprising a revolving frame or main body 2 rotatably
mounted on a radial base 3a for swinging movement about
a central axis 3 along with a boom 4 mounted to the
frame. Extending upward from a hoist rope drum 27
secured to the revolving frame is a hoist rope 9 which is
trained around a head sheave 7 and then hanqs down.
Suspended from the forward end of the hoist rope is a
bucket 6. A-drag rope 8 extending from a drag rope drum
27a is also connected to the bucket 6. ~he walking dragline
1 is adapted to move around on its legs (not shown) which
can be extended downward from the revolving frame 2 as
required.
The excavating method according to this
invention will first be described with reference to
Fig. 2. If the bedrock to be excavated is excessively
hard, the rock is beforehand broken to pieces by blasting.
The excavated material is then scraped into the bucket 6
of the walking dragline 1, and the boom ~ is swung to
move the bucket to a position over the hopper 14 for
(~ ~4
dumping the material into the hopper. The material is
deposited through the hopper onto the belt conveyor 13 to
be hauled thereby. This procedure is repeated until
the dragline has finished digging the soil and rock
within the reach of the dragline located at a fixed place,
whereupon the dragline is moved to another location to
continue with the excavati~g operation in a similar manner.
The tilt angle of the boom can be adjusted, but as it
requires much time, the boom is usually operated at a
fixed dip angle for a particular work unit under the
same working conditions. The range of movement of the
dragling is limited to an arc with its center at the
center 14a of the hopper 14 and with the length r of the
boom as a radius, as shown in Fig. 3. The length of
the boom is specifically defined as the distance between
the forward end 5 of the boom and the central axis 3 of
the revolving frame 2. On the other hand, the lateral
wid~h of one digging or cut zone is designed such that as
long as the dragline moves around within said range of
movement it can perform the excavation. When the excavation
wqthin---the limits as defined by a particular fixed locatior
of the hopper 14 is completed, the hopper is moved along
the belt conveyor 13 by a distance equivalent to one
dragging or scraping stroke of the dragline 1. Then, the
dragline is moved to a position which accommodates the
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distances with respect to both the hopper 14 and the
working face 12 and continues with the excavatiOn in
a similar manne~. In this manner the excavation work is
continued as the dragline 1 and hopper 14 are moved stepwise
along the belt conveyor 13. When the dragline 1 thus
reaches the end of the whole working area, the dragline,
hopper 14 and belt conveyor 13 are all shifted laterally by
a distance equal to one cutting width of the dragline to
continue with the digging of the next adjacent zone to be
dug of the area in a similar mannerO In this case~ the digging
equipment may be returned to a location adjacent the
starting point of the preceding working zone to effect
the excavation in the same direction as with the preceding
digging. Or-alternatively, the excavation may be turned
back from the terminal end of the preceding digging zone
to proceed with the excavation of the next zone in a reverse
direction.
In order to dump the excavated material precisely
over the hopper, first of all the dragline must be located
at a proper position, that is, on the aforesaid arc
with the radius r about the center of the hopper. However,
it is troublesome to position the dragline and the
hopper as by using a measuring tape each time the dragline
and/or hopper are displaced. This problem may advantageously
be solved by using an optical distance measuring equipment
P2 rh~P 9~
such as a stadia telescope or an ordinary distance measuring
instrument. Taking into account the fact that the boom
is about 50 to 100 m in length, it will be sufficient if
the accuracy of~the measurement is 1l0 to 210 or better
in which case the error will be less than 50 cm.
For the positioning procedure it is required ~nly
initially to move the dragline in an actual trial so
that the forward end S of the boom is positioned just
above the center 14a of the hopper. Once the boom end
has been aligned with the hopper center, the optical
distance measuring instrument 11 is maneuvered at the cah
of the dragline to be pointed at the center 14a of the
- hopper and fixed in place with respect to the dragline,
and the distance is read from the instrument. The
distance thus read is defined as r'. Once this setting
has been established, the operator can measure the
distance from the dragline to the center of the hopper by
the optical distance measuring instrument as the dragline
or the hopper is moved around, and if the distance is equal
to r', it means that the central axis 3 of the revolving
frame 2 lies on an arc with a radius r' about the center
14a of the hopper. The operator can thus make the
positioning operation by himsel~. Although the positioning
procedure has been described in a more or less typified
manner for the benefit of simplicity, in practice the
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z~
bucket 6 is offset inwardly toward the drayline hody
as shown in Fig. 4 rather than lying right below the
head sheave 7 during the dumping action. However, it is
only required to make the initial positioning operation,
and subsequent distance measurements may be made with
the bucket 6 in alignment with the center of the hbpper.
The method of controlling the movement of the
bucket will now be described. The bucket of the properly
positioned dragline is moved around over the entire working
face 12 during the digging operation. But, the dumping
position of the bucket is fixed in both a horizontal and
vertical plane. Accordingly, it is possible to insure
the positive dumping motion of the bucket over a narrow
hopper as well as to substantially reduce the cycle time
of the dragline by automatically controlling the
movement of the bucket between at least the completion
of the scraping action and the dumping action. As a method
of accomplishing the automatic control it is conceivable
to install a photoeIectric tube or radio beacon on or
adjacent the hopper so as to detect the proximity of the
bucket or boom and feed a signal back to the dragline
for controlling. However, such method involves some
unreliability due to external disturbances. In addition
it is unsatisfactory from a view-point of installation
cost and maintenance services in that it requires either
- 15 -
a communication cable or signal generator for t~nsmitting
detected signals to the dragline which is a mobile rnachine.
One o'f the most preerable methods is to
accomplish the~automatic control on the basis of the
number of residual pulses adapted to be produced in
direct proportion in number to the number of revolutions
of the associated drive shafts of the revolving frame,
drag rope drum and hoist rope drum, said pulses having
positive and negative signs depending on the direction
of rotation of the associated drive shafts.
The automatic control according to the invention
will be described in details as follows:
(1) Control of the rotation of the revolving frame (hence
the boom):
A pulse signal generator is installed on the
drive shaft of a drive motor for rotatively driving the
revolving frame or on the transmission between said
drive shaft and the driven revolving frame, said signal
generator being arranged to produce pulses proportional
to th~ number of revolutions and having positive and
negative signs depending on the direction of rotation
and to provide the pulse signals to a pulse memory where
the positive and negative signals cancel each other.
Positive and negative signs of pulses may be discriminated
either by the pulse shape or by discriminating the direction
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of rotation of the electric motor.
In operation of the dragline the orientation of
the boom is preliminarily aligned with a reference line
extending betweën the central axis 3 of ~he revolving frame
and the center 14a of the hopper and the pulse memory is
reset at zero to eliminate any residual pulses, so that
the angle formed between the orientation of the boom and
the reference line (as will hereinafter be referred to
as horizontal angle of the boom) is directly proportional
to the number of residual pulses in the memory with the
angle and the number corresponding with each other at 1
to l. After the scraping action by the hucket is completed,
the acceleration, constant speed movement and deceleration
of the revolving frame are successively effected by the
automatic controlling according to the number of residual
pulses corresponding to the preset horiæontal angle
of the boom. The control operations are preliminarily
programmed in a computer on the basis of calculations and
actual experiments so that a maximum efficiency in
operation may be obtained. The machine is operated
in accordance with the instructions from thé comuter.
In Fig. 5a, by way of example, the automatic control
is initiated at the digging point (A) whe~eupon the
revolving frame is increasingly accelerated in its swinging
movement into the constant speed travel at point (C),
- 17
and then is dece]erated at point (D3 until it is bxought
to a halt at point (B). These controls are effected by
means of the computer according to the numbers of residual
pulses (W), ~X)~, (Y~ and (Z) corresponding to the positions
(A~, (C), (D) and (B), respectively of the boom. The
return travel of the empty bucket is usually manually
controlled because the digging point (A) is changed
from time to time. In some instances, however, an
initial portion (fixed portion) of the return travel or
swing may be incorporated in the automatic control.
(2) Control of the drag rope and hoist rope:
As with the control of the rotation of the
revolving frame, a pulse signal generator is installed
on each of the drag rope and hoist rope drums, said generator
being adapted to produce pulses proportional in number to
the number of revolutions and having positive and negative
signs depending on the direction of rotation so that
the pay-out (release) and wind-up (pull) of the associated
rope may be automatically controlled according to the
number of residual pulses which number corresponds with
the length of the released rope at 1 to 1. (However,
the relation between the numbex of pulses and the paid
out leng~h of the rope is not necessarily proportional
in the case of a drum having more than two plies of
rope wound thereon in which one turn of rope in the inner
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-
; ply is shorter than one turn of rope in the outer ply.)
~or example, in Fig. 5b the material is scraped into
the bucket by manual control in steps 1 to 3,,thereupon
the automatic control is initiated wherehy the drag rope
is released while the hoist rope is wound up until the
hoist rope is shortened to the length suitable for dumping
(in step 4). At this point both of the ropes are stopped,
and then in step 5 when the bucket is positioned right
over the hopper, only the arag rope is paid out to dump
the material. It should be'noted that the instructions
to stop the two ropes in step 4 are issued accordiny to the
number of residual pulses corresponding to the paid
out lengths of the two ropes whereas the instructions
to release the drag rope'in step 5 are issued according
to the number of residual pulses of the revolving frame '-
corresponding to the hori~ontal angle of the boom when
the bucket is brought to a position just above the hopper.
Upon completion of dumping~,the return step 6 is performed
by manual control back to the digging step 1. It is
because the digging point is changed from time to time
over the working face .that the'-return.'and digging ,,..-,
steps are manually controlled. The point at which the
mode of control is switched from manual to automatic (in
other words the paid out lengths of the drag and hoist ropes
when the operation is switched from digging to transportation~
-- 19 --
'- ~.$~2.r~J~
is not constant for each cycle, either. For example,
sometimes it may be in the condition as shown in step 2
and sometimes i'n the condition shown in step 3.
However, even though there is a variation in the point at
which the automatic control is initiated, it is possible
to make the automatic control by a single program since
the rope motions after the automatic control has been
initiated are fixed in that the drag rope is m~ved in the
sense to be released while the hoist rope is moved in
the sense to be pulled. Further, if there are irregularities
on the terrain, the height from the hopper to the forward
end of the boom may vary as the dragline is moved. To
cope with such situation, the level or elevation of the
bucket, hence the paid out lengths of the two ropes just
prior to the dumping action are determined by an actual
measurement each time the dragline is moved, and the
number of residual pulses corresponding to said paid
out lengths are cleared to reset the memory at
zero whereby the automatic control may be performed by
a single program.
As stated above, only one program is usually
required. But when there are substantial changes in the
working conditions, more than two programs suitable to ~;
meet expected working conditions may be prepared in
advance so that an optimum program may be selected for
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particular conditions.
~ he method of controlling the bucket utilizing
an auxiliary rope will now be descr;bed. ~lthough the lateral
movement of the~ bucket during the dumping operation may
be substantial~y perfectly controlled by the automatic
control so far described, the control of the forward-
rearward or longitudinal oscillation of the bucket is not
sufficient. The hucket is designed such that it is
maintained in a generally horizontal attitude as well as
being prevented from rocking motion by keeping the drag
and hoist ropes under tension~ An angle X is thus formed
between the hoist rope 9 hanging down from the head sheave
7 and the plumb line 7a from the head sh~ave (see Fig. 4).
Therefore, if the drag rope 8 is slackened, the bucket
is displaced toward the plumb line 7a so that the
excavated material is dumped over a correspondingly wider
area, resulting in requiring a larger hopper. In order
to avoid this problem, the present inventlon employs a
third or auxiliary rope in addition to the drag and
hoist ropes. More specifically, the auxiliary rope 10
(Fig. 6) extends from a third or auxiliary drum mounted
to the revolving frame 2, passes around the head sheave
7 and is connected to the bucket 6 for the purpose of
controlling the tilt angle of the hucket as it carries
the excavated material. As shown in Fig. 6, preferably
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the auxiliary rope 10 is connected at one end to the arch
6C of the bucket, passed around an auxiliary pulley 6b
connected in tandem to a dump rope pulley 6a, and trained
around the head sheave 7. With this arrangement the
bucket is maintained stably in its horizontal attitude
- during the transfer or transportation, and a smooth dumping
action is also insured. The function of the auxiliary rope
is to control the tilt angle of the loaded bucket during
the transfer and to share the load of the loaded
bucket with the hoist rope while maintaining the controlled
tilt angle of the bucket until it is unloaded. Accordingly,
it is required to change the difference between the paid
out lengths of the auxiliary and hoist ropes only when
the tilt angie of the bucket is changed. At all other
times the two ropes may be moved in unison in their pay-out
and wind-up motions. That is, upon completion of the
scraping and prior to the transfer of the bucket, the
lengths of the two ropes are adjusted to maintain
the bucket in its horizontal attitude, and during the
dumping action the auxiliary rope alone is released.
` As indicated aboveO since the addition of
the auxiliary rope does not make the operation of the
dragline so complexed, the manual operation using the
auxiliary rope is possible and effective in its own
way. But as stated hereinbefore t as the manual operation
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t! ~
is inefficient, it is preferable to make ~he automatic and
integrated control of the boom 4, drag rope ~, hoist rope 9
and auxiliary rope 10.
The aùtomatic control of the dragline with the
auxiliary rope is described as follows: In Fig. 7a the
boom is moved between the digging position (A) and the
hopper position (B). Fig. 7b illustrates the sequential
~otions of the three ropes as the boom is moved between the
positions (A) and (B). In step 1 the hoist and auxiliary
10 ropes are paid out while the drag rope is wound up
to be ready for digginy. These ropes continue to be
moved in the same directions as the digging work proceeds
until it is finished in step 2. During this time the
bucket has been rotated nearly 90 from its approximately
vertical to horizontal position so that the auxiliary
rope has sagged. To eliminate this sag the auxiliary
rope alone is wound up in step 3 while the hoist rope
is halted. Thereafter, in step 4 the hoist and auxiliary
~; ropes are wound up while the drag rope is paid out to
20 lift the bucket to a level suitable for dumping. At
this time the bucket is suspended generally directly
below the head sheave because the drag rope is imparted
i~ a tension just enough to prevent the rocking motion of
the bucket. In this condition the boom continues to be
rotated to bring the bucket to a position right above the
'
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. ,
hopper whereupon in step 5 the auxiliary rope is released
and the drag rope is slackened to unload the hucket.
Thereafter, the,bucket is lowered through a manual control
in step 6 and b,ack to step 1 for digging. All the foregoing
motions of the''ropes are 'controlled by the number of
residual pulses corresponding to the paid out length of
the respective ropes', except that the in,structions
as to the motion of the ropes' during the dumping action
in step 5 are issued according to the number of residual
pulses of the revolving frame.
One technical difficulty attendant to the
operation employing an auxiliary rope is how to balance
the hoist and auxiliary ropesO The hoist and auxiliary
ropes suspending the bucket at opposite ends are
substantially independent of each other in contrast
to the`drag and hoist ropes which are in pulling and ^'
constraining relation with'each'other. It is quite
difficult to accomplish such a delicate control as to
drive'two independent ropes separately by two motors and
yet maintain the bucket in a horizontal attitude.
To solve this problem the inventors have developed '
a method of driving the'two ropes by a single motor by
analyzing the mokions of the'hoist and auxilliary ropes.
The sequential motions o~ the ropes as shown in Figs. 7a and
7b are summarized in Table I for the benefit of clarity.
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Comparison between the motions of the hoist and auxiliary
ropes in Table I shows that through the manual and automa~ic
portions of control both of the two ropes move in the
same manner (steps 1,2, 4 and 6) or otherwise the auxiliary
rope alone moves while the hoist rope remains stationary
(steps 3 and 5~. Accordingly, a single prime mover may
be provided to drive the two ropesO Preferably, the
prime mover is connected directly to the drum of the
auxiliary rope which does not stop at any point o~ time,
and said drum is connected through a clutch to the drum
of the hoist rope. Of course, this driving system would
have no trouble in stopping both of the drums.
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~ O ~ ~ I ~ ~
tn ~ td ~ td :~
O td ~,~ .1: 3 ~: td
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o m
n ~ ~~: ,¢ ~ m
P~ __ __
m
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-- 26 --
2~4~
Fig. ~ schematically illustrates the principle
on which the drive system of the invention operates. At
the right side of Fig. 8 there is shown a prime mover 22
to which an auxiliary rope drum 25 is coaxially connected
through a reducer 23 and a brake 24. A hoist rope drum
27 is connected to the auxiliary rope drum through
a clutch 26 and a brake 24a. The two drums have pulse
signal generators 28, 28 associated with their respective
shafts. Considering this drive system with reference to
Table I, the clutch 26 is actuated in steps 1 and 2 to rotate
both drums in the release direction and then bring them
into an idle condition. In step 3 after both drums have
stopped the clutch 26 is disengaged, and the auxiliary rope
drum 25 alone is rotated in the pull direction. In step
4 the brake 24a of the hoist rope drum is released and -'
the clutch is engaged to rotate the hoist rope drum 27
` along with the auxiliary rope drum 25. In step 5 after
both drums have stopped, the clutch is disengaged and
the auxiliary rope drum alone is rotated in the pay-out
or release direction. In step 6 the clutch 26 is again `;
engaged to rotate both drums in unison in the release
direction. In this manner the hoist and auxiliary ropes
can be operated very smoothly. The drive system as described -
- just above using a single prime mover may be equally
applicable to the manually controlled operation.
- 27 -
Here attention is directed to the meaning of the
term "auxiliary rope" as herein used. Most heavy~duty dragllnes
employ a dual-rope suspension system for the hoist rope
means (also for the drag rope means) comprising two drums,
two head sheaves and two ropes. In such instance the
auxiliary rope system according to the invention may be
adopted simply by adapting one of the dual hoist ropes for
the auxiliary rope without the need for providing an
additional single or dual-rope type auxiliary rope means,
because the load of the bucket is shared by the hoist
and auxiliary ropes just as it is by the dual hoist ropes. r
Accordingly, no additional drum or head sheave for the
auxiliary rope is required except that the connection of
one of the dual suspension ropes to the bucket and the
driving connection of the two drums need be modifiedv
The use of the automatic control according to
the invention enables a reduction in size of the hopper
for receiving the excavated material from the bucket.
The planar dimensions of the hopper may preferably be
such that one side of the hopper is 1.0 to 2.5 times
as long as the length of the bucket. With less than
1.0 times, the dumped material can spill out the bucket,
and with greater than 2.5 times, it becomes difficui~ to
displace the hopper. More specifically, for the automatic
control u~ing the auxiliary rope it is particularly
- 28 -
preferable that the size of the hopper be such that one
side thereof i5 1. 2 to 1.5 times as long as the hucket.
For the automatic control without the auxiliary rope,
the hopper is very preferably sized such that the length
one side thereof is 1.5 to 2.0 times that of the bucket.
The method of disposing of large lurnps contained
in the material dug will be described. Large lumps in the
excavated material are separated by an inclined sieve means
disposed over the hopper body to prevent them from falling
into the hopper. When large masses of rock or stone in
the excavated material are in a relatively small amount,
the separated large masses are put aside on the ground,
and as a certain amount of masses is piled up, they may
be loaded on trucks as by front-end loaders and carried
out of the working area. Turning back to Fig. 2, there
is shown a method of processing large lumps in a more
efficient manner in the case a great quantity of coarse -
~` masses is contained in the material dug. Large lumps are
deposited on the coarse mass belt conveyor positioned
adjacent the discharge end of the inclined sieve 15, broken
to piecesof an appropriate sizeby acrusherl9 and withdrawn
by a haul-off conveyor 2~. The broken frayments are then
dropped through a chute 21 back onto the belt conveyor 13
extending below the hopper to be carried away together
with those fine particles of the exacavated material passed
- 29 -
2~
through the sieve. One form of large lump conveyor i5
known in which the frame is equipped with shock absorbing
springs. A large-sized douhle chain conveyor may also
be used. ~
While any type of known crusher may be utilized
for this purpose, a jaw crusher which is suited to
process large masses and which may be made compact in size
is especially desirable in the case it is not required
to break the lumps to very fine pieces. For the haul-of~
conveyor, any ordinary belt conveyor or double chain
conveyor may be employed.
All of said large lump conveyor 18, crusher 19
and haul-off conveyor 20 may either be mounted on a wheeled
platform or may have their legs provided with boat-shaped
shoes or wheels like the hopper as will be hereinafter
described, whereby they may be movable along the belt
conveyor 13. These components may be moved by
towing them by heavy-duty machines such as a heavy-duty
bulldozer, loader or the like. In some instances they
may be pulled by a dragline.
The method of applying the foregoing process
of digging by the combination of a dragline and belt
conveyor to the mining of multiple~strata coal mine will
next be described. This invention provides a method
comprising the steps of digging an overhurden Or an
~ 3~ -
upper layer of earth overlying the Jowermost coal seam
by a drgline and depositing the excavated material directly
on the gob area of said lowermost coal seam; and diyging
overburdens o~coal seams above the lowermost coal seam
by respective draglines and loading and transporting the
excavated material on belt conveyor means laid parallel
to the associated zones of the mining area by means of
hoppers movable along the associated belt conveyors, This
method will be fully explained with reference to the
; 10 drawings. Fig. 9 is a plan view of a stope in which
three-strata coal seams are simultaneously mined.
Fig. 10 is a sectional view taken on the line (A)-(A)
in Fig. 9. The coal seams are called first, second and
third coal seams 49, 50 and 51 in the order from the
top downwardl and the earth layers overlying the
respective coal seams are called first, second and third
overburdens 52, 53 and 54. The stratum comprising the
first coal seam and first overburden is referred to
; as first stratum. The two similar lower strata are
termed second and third strata. A dragline 1, face
conveyor 55 and hopper 14 are installed on each of the
first and second strata. Extending along the outer
boundary of the mining area is an intermediate conveyor
56 which is disposed generally at right angles to the
face conveyors and into which the face conveyors discharge.
Further, a gob conveyor 57 is laid at the gob or waste area
to receive the discharge from the intermediate conveyor
and is arranged to discharge into a stacker 58 for spreading
the excavated material over the gob or waste area 59 from
which the coal has already been extracted. On the third
overburden a drayline 1 only is installed. In genera],
shiftable belt conveyors are preferably used for the face
conveyor 55 and gob conveyor 57 while the intermediate conveyor
56 may preferably be a fixed conveyor. Further, when a
relatively large proportion of big lumps is contained in
the material dug, a large lumps conveyor 18, crusher 19,
haul-off conveyor 20 and chute 21 may advantageously be
used in conjucntion with the hopper 14 as described
above in connection with the arrangement of Fig. 2.
The digging is carried out successively with
the first, second and third strata in the order named. The
digging of ~ach stratum proceeds from the starting point
(not shown) toward the intermediate conveyor 56 along the
face conveyor 55 usually with a cutting width of 30 to 50 m.
First, uppermost or first overburden 52 is broken to
fragments by blasting and dug by the dragline 1 in the same
manner as described hereinabove in connection with Fig. 1.
The excavated material is then loaded through the hopper
14 onto the face conveyor 55 which discharges into the
intermediate conveyor 56. The excavated material is
- 32 -
~$~
then discharged into the gob conveyor 57 and ultimately
dumped through the stacker 58 behind th~ mining area. Upon
completion of the digging within the limits from which
dragline l can reach the hopper 14, the dragline and
hopper are moved to continue with the digging of the
first stratum 52 in the same manners. When an appropriate
length (usually 100 to 200 m) of the first coal seam 49
immediately below the first overburden 52 has heen exposed,
the mining of the first coal seam is initiated from the
remote end thereof to proceed toward the working face 12
~` of the first overburden. The coal mining may be effected ~ -~
by any conventional mining method using explosivesj power
shovels, trucks (any of them not shown), etc. As the
excavating operation has proceeded to the terminal edge
of the mining area adjacent the intermediate conveyor),
the equipment including the face conveyor 55, hopper 14
and dragline l are transferred to the adjacent second
zone of the first or uppermost stratum to dig the second
cutting zone from the starting end towards the intermediate
conveyor in the same manner. In this way the first stratum
continues to be dug one zone after another.
Upon the digging and mining of the first stratum
having thus proceeded to a certain extent, the digging
of the second stratum is initiated with a space of one
or two cutting widths from that zone of the first stratum in .
- 33 -
process of digging. The spacing of one or two cutting
widths insures a space for laying a face conveyor for the
second overburden digging as well as isolating the second
stratum from the influence of blasting in the first stratum.
The digging of the second stratum is effected in the same
`~ way as the first stratum. Upon digging of the second stratum
having proceeded for a few cutting zones, the digging of the
third stratum is started. The~third overburden is first
excavated. In this case, however, it should be noted that
the excavated material is dumped over the gob area 59
directly by the dragline 1 without using a face conveyor.
The other operations are the same as the digging of the
first and second strata.
The excavations of the first, second and third
strata thus proceed such that each succeeding stratum
follows the immediately preceding one. The excavated
material from the third overburden is piled on the
waste area of the third stratum to fill it in the wake of
the progressively worked third stratum. The excavated
materials from the first and second overburdens are piled
successively ont~e excavated material of the third overburden
previously dumped on the waste area. Accordingly, as the
digging of the various strata proceeds, the gob conveyor
57 is transferred progressively forward. The entire
mining area is thus a system moving parallel in an
- 34 -
~ 4
orderly manner which provides a very high efficiency
in operation with shortened distances o~ travel throuyh
which the excavated material is transported and a
~ minimum working`space required for the mining operations.
;r~ It is to ~e appreciated that the foregoing mining
method according to this invention using draglines jointly
with belt conveyors enables the mining of multiple-stratified
coal seams which has heretofore been impossible with the
prior art method using draglines alone.
The present invention is not limited to the
embodiments herein illustrated hut may be practiced
in many different forms without departing from the
spirit and scope of the invention. By way of example,
even in the case of a single stratum coal seam, if the
overburden above the coal seam is so thick as to exceed
the working capacity, the digging of the overburden may
be effected efficiently by dividing the overburden into
an appropriate number of layers so that those layers
may be worked by the multiple-strata digging method of
this invention. Since the efficiency of the strip mining
depends for the most part upon the efficiency of mining
of overburden, the industrial value of this invention is
considered extremely high.
Figs. 11 to 16 illustrate preferred forms of
the haulage or transport apparatus according to the invention.
- 35 -
\4
Throughout these drawings like component par-ts are designated
by like reference numerals.
Refer~ing to Fig. 11, there is shown a hopper
body 34 straddllng the belt conveyor 13, the hopper body
including a pa;r o~ opposed side walls 33, 33 extending
parallel to the longitudinal axis of the belt conveyor 13
and sloping downwardly inwardly toward the conveyor to
form therebetween a discharge opening through which
the excavated material is deposited onto the conveyor 13.
A pair of opposed end walls (not shown) of the hopper
body 34 extending transversely to the belt conveyor 13
may preferablv be disposed generally vertically in order
to provide an increased area of the discharge opening and
facilitate smooth dropping of the material along those
hopper walls, although the end walls may be inclined with
respect to the vertical plane transverse to the conveyor,
if desired.
One of the opposed wide walls 33, 33 is made higher
than the other to define an enlarged mouth opening for loading
the material dug. Extending across the mouth opening is
an inclined sieve means 15r Material dug is dumped over
the sieve means 15 by the bucXet 6 of the dragline 1 ~Fig. 6)
and finer particles passing through the sieve are loaded
onto the belt conveyor 13 to be hauled to an appropriate
place (not shown).
- 36 -
~ 2~J'~ ;
~.
;` Installed juxtaposition the hopper body 34 is
a large lump belt conveyor 18 which is adapted to receive
and haul the large lumps of soil and rock separated by
the inclined sleve means 15.
The side walls 33, 33 of the hoppex body are mounted
,~ to supporting framework 35 on the bases 30 of which are
mounted boat-shaped shoes 31 which ride slidably on sleepers
: 32. The large lump belt conveyor 18 is constructed in a
similar manner.
Fig. 12 shows another embodiment of the hopper
means in which the hopper body 34 has a reduced top opening,
hence a reduced hopper capacity and a small inclined sieve
15. In this embodimen~, however, an inclined material
receiving plate 16 is integrally and coextensively joined
to the upper side edge of the sieve 15. This hopper means
is characterized in that the unitary inclined sieve 15
and inclined receiving plate 16 is connected to the
framework 35 by means of fluid operated piston-cylinders
37 so that the sieve and plate unit may be adjusted -
in its tilt angle by actuating the piston-cylinders. -
In operation, with the piston-cylinders 37 retracted to
hold the sieve and plate unit at a gentle angle, the
hopper receives the material dug from the dragline
bucket. After some of the relatively fine particles of
the material which passed through the sieve portion 15
- 37 -
,-. ~, ~,
I'
and fell into the hopper body 34 have been c~r~ied away,
the piston-cylinders are extended to tilt the unit o sieve
lS and plate 16'to a steeper angle as shown in dash-dot
lines in Fig . 1~2 . with this arrangement~ some of the
; material dumped from the ~ucket is temporalily accumulated
on the inclined receiving plate 16, enabling reduction
in capacity of the hopper body 34. In addition, large lumps
slide down the inclined sieve 15 after they have once
come to rest, so that damages to the large lump conveyor 18
may be greatly relieved as compared with the arrangement
wherein the excavated material are dumped from the bucket
at a high elevation with accelerated velocity onto the
inclined sieve and immediately slide down the sieve.
Since the energy of collision of the large masses of
soil and rock is proportional to the square of the velocity ~ -
of collision, a great effect is obtained by reducing the
velocity of the sliding down masses. As a result, the
large lump conveyor 18 may require less structural strength
and be made lighter in weight. Another advantage
of this form of hopper means is that it is relatively low
in height and dividable into three parts - the body
portion, piston-cylinders and inclined sieve portion to
thereby greatly facilitate the movement of the hopper.
Fig. 13 shows a still another form of the
hopper in which the hydraulic cylinder means as used in
- 38 -
':
~;
` the embodiment of Fig. 12, as an elevator for liftlng the
`~ inclined sieve 15 and receiving plate 16 is substituted
'~` for by a less e'xpensive hoist means comprising a hoist
motor and drum (not shown), a post 38, rope 39, and sheave
39a. In this case, the hoist means may be installed on
the large lump conveyor side, instead of the side of the
belt conveyor 13 opposite from the large lump conveyor.
The dash-dot lines in Fig. 13 shows the inclined unit
of sieve and receiving plate in its lifted position.
Fig. 14 shows an alternate form of the hopper
in which the inclined receiving plate 16 is separate from
the inclined sieve 15 and supported at a higher elevation
than the sieve by a supporting framework 35 separate from
the framework of the hopper body 34. Further, the receiving
plate is inclined in a direction opposite the direction -
of inclination of the sieve. This hopper has characteristic
features intermediate between the embodiment of Fig. 11
and the embodiments of Figs~ 12 and 13. Thus, large masses
drop onto and slide down the inclined receiving plate
16~ hit the inclined sieve 15, change their direction
and slide down the sieve onto the large lump conveyor 18
with reduced shock against the conveyor. Furtherl the
framework is divided into two sections or the hopper body
and the receiving plate so that it is convenient for shifting.
Another advantage of this embodiment is that since the
39 -
large lump conveyor 18 is sheltered by the receiving plate
16, there is little possibility of the material dug
dropping and damaging the conveyor 18 as during a trial
bucket operation.
The supporting frameworks in the embodiments
of Figs. 11 to 14 are all provided on their bases or feet
with boat-shaped shoes 31 which are adapted to ride on
~he sleepers 32 as means for moving or shifting the
entire hopper. However, when such hopper means is
large-sized and heavy, it is not easy to transport.
While it is preferable from a viewpoint of transportation
that the hoppe framework be wheel-mounted to ride along
rails, the wheel-mounting is not desirable because during
the operation the hopper is subjected to impact load
by large masses as dumped from the dragline bucket, in
addition to the static load. To overcome this problem,
the present invention provides framework bases which are
adapted to be supported by fixing legs during the operation
and which are supported on wheels during the transportation
of the hopper. An embodiment incorporating such bases
is illustrated in Figs. lS and 16. As shown, the lower
portions of the leg posts 43 only one of which is shown
constitute fixing legs 41 downwardly spread out to form
bottom tread faces 40. A support arm 42 having a wheel
44 attached to one end thereof is pivotally mounted at the
- 40 -
other end to each of the leg posts ~3 above the fixing leg
41 by a pivo~ shaft 45. Each leg pos~ 43 has jack supports
46 extending from its opposed sides, each of the jack
supports having a jack 47 secured to its bottom.
During the operation of the hopper, the wheels 44 are
pivoted upward away from the associated rails 4~ as shown
in dash-dot lines in Fig. 16 and the jacks 47 are retracted
to cause the tread faces 40 of the fixing legs 40 to rest
on the sleepers 32 to thereby support the hopper on the
fixing legs 41. To move or transport the hopper the jacks
47 are extended to lift the tread faces 40 of the fixing
legs 41. The wheels 44 are then lowered over th~ rails 48
and the jacks 47 are retracted to engage the wheels w.ith
the rails. After the hopper has been pulled to a desired
location by a heavy-duty machine (not shown), the jacks
47 are extended to lift the wheels 44 from the rails to
permit the pivoting of the wheels upward, and then the
jacks 44 are retracted to lower the fixing legs 41
nto engagement with the sleepers 32. It is to be appreciated
that this base support arrangement not only facilitates
the movement of even large-sized heavy hoppers but also
provides security against impact loads during the dumping
of the material.
This arrangement is also applicable to the
large lump conveyor, crusher and haul-off crusher described
hereinabove.
- 41 -
. :
