FLECHE DE FORATION

DRILLING BOOM

Abrégé anglais

ABSTRACT
A drilling boom is pivoted about a first axis on a base and is pivoted
about that axis by a first hydraulic cylinder. It carries a feeder beam
carrier at its forward end. The carrier is pivoted at the forward end of
the boom about a second axis which is parallel to the first axis, and it
is moved about the second axis by a second hydraulic cylinder in a sense
opposite to that in which the boom is moved by the first cylinder. The
first and second cylinder are so dimensioned and hydraulically
interconnected that fluid which is expelled from the first cylinder
actuates the second cylinder and vice versa. The angular movements of
the boom and carrier are equal in magnitude.

Revendications

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THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
Claim 1:
A drilling boom assembly comprising:
a base,
a drilling boom,
a feeder beam,
a carrier for the feeder beam at the forward end of the
boom,
a bracket on the base pivoted about a first axis parallel
to the base,
a pivot on the rear end of the boom for causing the boom
to pivot on the bracket about a second axis at right
angles to the first axis and also parallel to the base,
means for pivoting the carrier to the boom about third and
fourth axes which are respectively parallel to the first
and second axes,
first and second hydraulic cylinders for moving the boom
about the first and second axis respectively,
third and fourth hydraulic cylinders for moving the
carrier about the third and fourth axes respectively in
senses opposite to the senses in which the boom is moved
by the first and second cylinders respectively,
the angular movements of the carrier about the third and
fourth axes being the same as the angular movements of the
boom about the first and second axes respectively,
and means to rotate the feeder beam about the longitudinal
axis of the carrier.

Description

SUE;
BACKGROUND TO THE INVENTION
This invention relates to a drilling boom of the kind in which a drill
feeder beam is carried at the forward end of an extensible boom which at
its rearward end is pivoted to a base to lift and slew.
5 Unless the feeder beam is properly tilted and its orientation readjusted
when the boom tilts and slews, the beam does not remain parallel to the
centre line of a tunnel and retain the same drilling orientation in all
positions to which the boom is adjusted. This may lead to less than
optimum blasting results.
10 It is an object of the invention to provide a boom which has an automatic
interface between lifting of the boom and tilting of the beam as well as
stewing of the boom and orientation of the beam.
Furthermore booms used currently result in a face coverage pattern
exhibiting curvature of one form or another erg; "hour glass" curvature.
15 It is another object of the invention to overcome this drawback.
SUMMARY OF THE INVENTION
According to the invention a drilling boom is pivoted about a first axis
on a base, the boom is moved about the first axis by means of a first
hydraulic cylinder, the boom carries a feeder beam carrier at its forward
20 end, the carrier is pivoted at that end about a second axis parallel to
the first axis, the carrier is moved about the second axis by means of a
second hydraulic cylinder in a sense opposite to the sense in which the
boom is moved by the first cylinder and the first and second cylinders
are so dimensioned and so hydraulically interconnected that fluid
25 expelled from the first cylinder actuates the second cylinder and the
other way round.
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In the preferred form of the invention the first and second cylinders are
in communication such that the angular movements of the boom and carrier
are equal.
Further according to the invention the boom is also pivoted about a third
5 axis at right angles to, and in a parallel plane to the plane containing,
the first axis, a third hydraulic cylinder causes the boom to move about
the third axis, the carrier is pivoted to the boom end about a fourth
axis at right angles to the second axis, a fourth hydraulic cylinder
causes the carrier to move about the fourth axis, and the third and
10 fourth cylinders are so dimensioned and so hydraulically interconnected
that fluid expelled from the third cylinder actuates the fourth cylinder
and the other way round.
In the case of the third and fourth cylinders the full bore and annular
chambers are preferably interconnected.
15 DESCRIPTION OF THE DRAWINGS
Figure 1 is a perspective view of one embodiment of the invention,
Figure 2 is a diagrammatic representation of two hydraulic cylinders,
Figure 3 is a view similar to Figure 3 of another pair of cylinders,
Figure 4 is a diagram illustrating the lift and tilt principles of the
20 invention, and
Figure 5 is a diagram of the slew and orientation principles.
DESCRIPTION OF EMBODIMENTS
In Figure 1 a boom 10 is carried on a base plate 11 secured to a suitable
conveyance. The boom 10 is extensible in a manner know per so. It is
25 pivoted about a lifting axis 12 on a bracket 13. The bracket 13 is
pivoted about an axis 14 parallel to the plate 11.

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Pivoted to the bracket 13 is a lift cylinder 15 extending to a pivot 16
or, the boom 10. By expanding and contracting the cylinder 15 the boom 10
is caused to move in a plane containing the longitudinal axis of the boom
10, the axis of the cylinder 15 and the axis 14. This will usually be a
5 vertical plane so that the boom is lifted and lowered by the cylinder 15.
A slew cylinder 17 is pivoted through a link 40 on a bracket 18 on the
plate 11 about an axis 19 parallel to the axis 14 and about a pivot 20 on
the boom 10. Expansion and contraction of the cylinder 17 causes the
plane in which the boom moves under the action of the cylinder 15 to
10 pivot about the axis 14 which will usually be vertical.
A feeder beam 30 is rotatable bracketed to a carrier 21 in a well known
manner. The carrier 21 is pivoted about an axis 22 on a bracket 23 which
in turn is pivoted about an axis 24 on the forward end of the boom 10. A
cylinder 25 is pivoted about a pivot 26 on the bracket 23 and about a
15 pivot 27 on the boom 10. The cylinder 25 is the tilt cylinder and by
expanding and contracting it the tilt of the beam 30 relatively to the
boom 10 may be altered.
Orientation cylinder 28 is pivoted at a pivot 29 on a bracket 31 fast
with the boom 10 and on a pivot 32 on the forward end of the boom 10.
20 With the longitudinal axes of the boom 10 and the carrier 21 in the same
plane expansion and contraction of the cylinder 28 causes the orientation
of the beam 30 to change in a plane normal to the last mentioned plane.
The various pivot lines and axes are so chosen and positioned and the
cylinders 15, 17, 25 and 28 so chosen that the following conditions can
25 be satisfied for all angular positions of the boom 10:-
Angular movement of the boom 10 about the axis 12 is equal and opposite to the angular movement of the carrier 21 about the axis 22.
30 Angular movement of the boom 10 about the axis 14 is equal and opposite
to the angular movement of the carrier 21 about the axis 24.-

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This is illustrated diagrammatically in Figures 4 and 5. In Figure 4 two positions of the lift cylinder 15 are illustrated, while in Figure 5 two
positions of the slew cylinder 17 are illustrated.
The manner of interconnection of the cylinders 15 and 25 is illustrated5 in Figure 2. When the cylinder 15 expands it pumps fluid from its
annular section 40 into the annular section 41 of the cylinder 25 along
the connection 42. For contraction fluid is fed into the full bone
section 44 of the cylinder 25 thereby pumping fluid from the annular
section 41 back into the annular section 40 of the cylinder 15.
10 On the other hand the cylinders 17 and 28 have to interact in a different
way. In this case the cylinders expand and contract simultaneously.
Such an action could be achieved by means of the structure illustrated in
Figure 3.
During testing, the inventors compared predicted lift, slew, tilt and
15 orientation angles with actually measured values of these angles, and
found a very good correlation between the two sets of values. For
instance, where a flit angle of 30 is caused by actuation of the
cylinder 15, the predicted tilt angle is also 30. A practical
measurement resulted in a tilt angle with exactly this value. Where the
20 slew angle resulting from appropriate actuation of the cylinder 17
resulted in a slew angle of 40, the measured slew angle was 39,15 which
represents a minor deviation only from the predicted slew angle of 40.
.
In addition, practical testing has shown that the upright walls of a mine
tunnel formed by blasting with drilled holes made by a machine fitted
25 with a boom of the type described exhibit very little deviation from the
vertical.