Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02218674 1997-10-20
WO 96/33337 PCT/FI96/00210
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A hydraulic arrangement for turning the actuator of a
rock drilling machine
The invention relates to a hydraulic
arrangement for turning the actuator of a rock drilling
machine about its turning axis to at least three
different positions, the arrangement comprising a
pressure medium cylinder provided with two cylinder
spaces and two pistons, the cylinder being arranged to
affect and turn the actuator, and at least one control
valve with which pressure fluid can be fed into the
cylinder spaces of the cylinder such that the two
pistons can be simultaneously fully ejected or fully
retracted, or one can be ejected while the other is
retracted.
In rock drilling machines and especially in
rock bolting machines, it is often necessary to turn
the actuator, such as a bolting head, which comprises
one or more devices, about an axis parallel to a drill
rod. In rock bolting, first a drill rod, then a feed
apparatus for feeding soldering material, and finally
a bolt feeding apparatus can be turned, in succession,
such that they align with the same axis, whereby the
soldering material and then the bolt can be fed into
the drill hole. Normally, this is effected by moving
different apparatuses ei.ther along transverse rails by
a linear movement or by turning the apparatuses about
an axis parallel to the axis of the drill rod by means
of hydraulic cylinders.
The problem with known solutions is that
accurate alignment requires either a separate cylinder
for each movement or mechanic stoppers to effect
sufficiently accurate alignment. Another problem is
that to control different movements, a separate control
lever is often needed for each movement, or a plural
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number of control levers will have to be used
simultaneously, which makes positioning difficult,
subjecting the process to errors.
The object of the present invention is to
provide a hydraulic arrangement by which control can be
implemented in a simple and reliable manner. - The
hydraulic arrangement according to the invention is
characterized in that the control valve can be placed
in at least three control positions but in only one at
a time; that in each control position the pressure
fluid is arranged to affect both cylinder spaces of the
cylinder so that in the control position concerned, the
pistons always settle in a certain predefined position.
The essential idea of the invention is that
each control valve is arranged to control both
hydraulic cylinders at the same time such that when a
control valve is in a certain position, the cylinders
settle in a certain predefined position, thereby
turning the drill machine to a certain predefined
position.
The arrangement according to the invention
makes it possible to always turn the actuator of the
rock drilling machine to a correct predefined position.
In the following, the invention will be
described in greater detail with reference to the
attached drawings, in which
fig. 1 shows a schematic view of a hydraulic
arrangement according to the invention,
figs. 2a to 2c show a schematic view of
positioning of a bolting head with the arrangement
according to fig. 1,
fig. 3 shows a schematic view of another embodiment of a hydraulic arrangement
according to the
invention, and
fig. 4a to 4c show a schematic view of
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positioning of a bolting head with the arrangement
according to fig. 3.
Fig. 1 shows a schematic view of an embodiment
implementing a hydraulic arrangement according to the
invention. In the figure, reference number 1 indicates
a bolting head functioning as an actuator of a rock
drilling machine. A cylinder 2 turning the bolting head
is a double cylinder with cylinder spaces 2a and 2b,
both of which comprise an independently moving piston
3a and 3b, respectively. Both cylinder spaces 2a and 2b
are connected to pressure-controlled pilot-operated
check valves 6, 7, 8 and 9 through pressure channels
4a, 4b and 5a, 5b, respectively, such that channels 4a
and 5a are connected to pilot-operated check valves 6
and 8, and channels 4b and 5b are connected in parallel
to pilot-operated check valves 7 and 9. Normally, when
no pressure is fed to the pilot-operated check valves
on their supply side, the valves close and stop the
flow of the pressure medium to and from cylinder 2.
Pilot-operated check valves 6 and 9 are
connected to control valves 11 and 12 through pressure
fluid channels lOa to lOc. Further, one pressure fluid
channel lOd coming from pilot-operated check valves 8
and 9 is connected directly to a pressure fluid
container 13. Control valves 11 and 12 receive pressure
fluid along pressure fluid channel 14, and,
correspondingly, pressure fluid channel 15 leads from
valve 11 directly to the pressure fluid container 13.
Figs. 2a to 2c show how valves 11 and 12
together with cylinder 2 control the bolting head. All
the figures show the positions of valves 11 and 12,
cylinder 2 and the bolting head after a control
movement. In a situation illustrated by fig. 1,
cylinder 2 is at its shortest, i.e. in one extreme
position. When control valve 11 is moved to a position
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according to fig. 2a, the pressure fluid can flow
through channel lOa to pilot-operated check valves 6
and 7. Valve 12 is then in free position as shown in
fig. 2a, and so it does not affect the operation in any
way. The pressure fluid then penetrates into the
cylinder spaces 2a and 2b through pilot-operated check
valves 6 and 7, behind the pistons 3a and 3b, whereby
pistons 3a and 3b project as shown in fig. 2a. Since
there is a partition wall between the cylinder spaces
2a and 2b in the double cylinder 2, the pressures
prevailing in the cylinder spaces have no effect
whatsoever on each other. The visible bolting head,
which is arranged to pivot about an axis 17 in relation
to a frame 16, is here in its extreme left-hand-side
position, and the drilling axis of a drill machine 18
is in a predefined position. A bolt feeding apparatus
19 and a concrete feeding apparatus 20 are then off-set
from line L.
When valve 11 is in free position, i.e. in the
middle position, no pressure fluid flows from channel
14, and cylinder 2 remains in its current position.
When valve 12 is pushed to the position shown in fig.
2b, the pressure fluid flows from channel 14 through
valve 12 to channel lOc and further through pressure-
controlled pilot-operated check valves 8 and 9 to
channels 4a and 5b. The piston 3a of cylinder 2a
remains ejected, but the piston 3b of cylinder 2b
slides inside until it is fully retracted. Here the
distance between the positions to which the piston rods
of the cylinder 2 are fixed is between the extreme
positions of the piston rods, but is always exactly of
a certain size. The bolting head 1 is here turned such
that the concrete feeding apparatus 20 is at line L, in
alignment with the above drilling axis.
When valve 11 is moved to the position shown
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in fig. 2c, the pressure fluid channel 14 is connected
to channel lOb, while channel l0a is connected through
channel 15 to the pressure fluid container. Valve 12 is
here in free position and does not affect the operation
5 in any way. The pressure fluid here flows from channel
lOb through pilot-operated check valves 6 and 7 to both
cylinder spaces 2a and 2b so that the pressure pushes
the pistons 3a and 3b inside the cylinder. Since piston
3a is already inside the cylinder, pressure fluid flows
only through pilot-operated check valve 7, also pushing
piston 3b inside the cylinder so that the cylinder 2 is
at its shortest, in the position shown in fig. 1. The
axis of the bolt feeding apparatus 19 and thereby the
bolt thereon align with the drilling axis at line L. In
accordance with figs. 2a to 2c, hydraulic control is
hereby effected: the pistons 3a and 3b of the double
cylinder 2 can be moved to three predefined positions
in order to pivot the bolting head about its axis. In
practice, valves 11 and 12 are preferably cross-
connected valves in one and the same valve unit: when
the control rod is moved forward or backward, the
cylinder 2 moves to the extreme positions, and movement
of the control lever from the middle position in the
transverse direction produces the intermediate
positions as shown in fig. 2b.
Fig. 3 shows an arrangement corresponding to
the one shown in fig. 1, with the exception that it
comprises a separate change-over switch, which is
needed since the cylinders of the double cylinder 2 are
designed to differ in length such that control of the
cylinder in different ways gives four predefined
positions. The operation and arrangement according to
fig. 3 are otherwise exactly the same as in fig. 1, but
the figure shows a separate directional control valve
22 that is arranged to change channels lOd and lOc with
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each other such that it is possible to make a choice
between two middle positions. In this embodiment, the
operation of valve 11 is exactly the same as and corresponds to the positions
shown in figs. 2a and 2c.
Likewise, the control of the middle position, i.e. the
-
operation and connections of valve 12, completely
correspond to fig. 2b, but the position of the double
valve 2 depends on the position of valve 22.
Figs. 4a to 4c, in turn, show the control of
the arrangement according to fig. 3 with the different
positions of directional control valve 22. Fig. 4a
shows the position of valves 11 and 12 when the
operation of the arrangement is to be controlled with
directional control valve 22. The position of
directional control valve 22 can be selected either
before using valve 12 or during its use. Fig. 4b shows
a situation where by the use of valve 12, one of the
pistons of the double cylinder 2, i.e. here piston 3a,
is retracted, while piston 3b is ejected. The change of
the position of directional control valve 22 in
accordance with fig. 4c produces a situation where the
positions of pistons 3a and 3b are reversed, i.e.
piston 3a is ejected and piston 3b is retracted.
Because of the different impact lengths of pistons 3a
and 3b, there are two different distances between the
heads of the piston rods of the cylinder 2, and so
there are two accurately defined positions between the
extreme positions of the ends of the piston rods of the
cylinder 2, whereby, e.g. when the bolting head is
turned, four permanent. turning positions are provided
for different actuators. This embodiment is useful when
there are four actuators and when it must be possible
to use each one of them in exactly the same position in
the axial direction. An example for this is a bolting =
head comprising a drill machine for drilling a hole, a
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solder resin feeding apparatus, a concrete feeding
apparatus, and a bolt feeding apparatus. In a situation
like this, a valve can be used for choosing whether to
use the resin feeding apparatus or the concrete feeding
apparatus, since both are not necessarily needed
simultaneously. When resin is to be fed into a drill
hole, the shorter piston rod 3a is retracted into its
cylinder space, whereby the bolting head 1 turns about
axis 17, and a tube 21 of the resin feeding apparatus
aligns with the drilling axis of the above drill
machine 18 in accordance with fig. 4b. If concrete is
to be used instead of resin, piston 3a remains ejected
from its cylinder space, whereas piston 3b is retracted
into its cylinder space, whereby a concrete delivery
hose 20 aligns with the drill hole as shown in fig. 4c.
Sometimes all four alternative positions are
needed in succession. Valve 12 can be connected in the
same way as valve 11: channel lOd is connected to one
channel of valve 12, and so a change-over can be
conducted between channels 10c and lOd by controlling
the valve so as to achieve the desired intermediate
position. On the basis of the above, this solution as
such is obvious to a person skilled in the art.
The invention is described in the above speci-
fication and the accompanying drawings only by way of
an example, and it is not in any way limited thereto.
The essential feature is that the control valves are
arranged to control both cylinders by forced control so
that a certain control movement always makes the cylin-
ders settle in a certain predefined position. Valves 11
and 12 are preferably cross-connected valves controlled
by a single control lever. The second position of valve
12 shown in the figures is not needed in the control
when only three control positions are used. Valve 12
can then have a simpler structure, or the second posi-
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tion can be used for controlling some other actuator.
When the same lever is to be placed in four control
positions, valve 12 must be implemented as depicted in
the figure. =
