LIQUID DRIVEN IMPACT DEVICE

DISPOSITIF DE PERCUSSION ENTRAINE PAR DU LIQUIDE

English Abstract

Liquid driven impact device provided with a housing (1) and a hammer piston
(2) movable to-and-fro therein. The hammer piston
is provided with channels (8) which when the hammer piston (2) passes the
impact position supplies pressure liquid to a valve body (9)
for locking this for continuous supply of pressure liquid to a first surface
(4) on the hammer piston (2) and to a flushing channel (6) for
continuous flushing of a drill hole.

French Abstract

Dispositif de percussion entraîné par du liquide comprenant un carter (1) et un piston percuteur (2) pouvant se déplacer avec un mouvement de va-et-vient dans ce dernier. Le piston-percuteur est pourvu de canaux (8) qui servent, lorsque le piston percuteur passe en position de percussion (2), à envoyer du liquide sous pression à un corps (9) de soupape pour verrouiller ce dernier afin d'apporter en continu du liquide sous pression sur une première surface (4) située sur le piston percuteur (2) et à un canal (6) de lavage pour laver en continu un trou de forage.

Claims

4
CLAIMS:
1. Liquid driven impact device comprising a housing,
a hammer piston movable to-and-fro in the housing for
exerting a drill tool to impacts in an impact position, said
hammer piston comprising a first surface which alternately
is connected to a liquid pressure source and to a reduced
pressure, whereby pressurization of said first surface
drives the hammer piston toward the drill tool, and a second
surface which during said movement to-and-fro is
continuously pressurized for loading the hammer piston in a
direction away from the drill tool, wherein said hammer
piston comprises a channel and when the hammer piston moves
past said impact position, said channel conducts pressure
liquid to a valve body for switching over and locking the
valve body for continuous pressurization of said first
surface for locking said hammer piston in a forward
position, wherein the forward position occurs when the
hammer piston extends further than the impact position
during upward drilling and wherein said channel also
conducts pressure liquid to a flushing channel for
continuous flushing of a drill hole.

Description

CA 02283447 2005-11-29
L.
29312-37
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Liquid driven impact device
The prESent invention relates to a liquid driven
impact devicE. More particularly the invention relates to
an impact devi.cE which makes it possible to temporarily
achieve continuous flushing of the drill hole at upward
drilling. The impact device is also suitable ~or downward
drilling.
It is previously known at downward drilling with a
compressible fluid driven down-the-hale drilling machine to
achieve flushing only of the drill hole through lifting of
the dxilli.ng machine, see LIS-A-9945929. Through this the
drill bit sinks so that the hammer piston of the drilling
machine can pass the normal impact position. T.he hammer
piston is thereby catched is a forward position so that only
flushing is achieved until the drilling machine is lowered
again and drilling is resumed. In order to avoid "back
hammering" the rear surface is loaded with compressible
fluid to keep the piston against the drill bit.. Tt is
doubtful if this method works at upward drilling without
damages to the retaining ring preventing the drill bit from
leaving the drilling machine. This prior art machine does
riot work with a liquid driving medium since it requires a
compressible fluid in oxder to function.
The present invention aims at ach~.eving a liquid
driven impact device which temporarily makes continuous
flushing or the drill hole possible at upward drilling.
In accordance wine an embodiment of the present
invention there is provided liquid driven impact device
comprising a housing, a hammer piston movable to-and-fro in
the housing for exerting a drill tool t.o impacts in an


CA 02283447 2005-11-29
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29312-37
1a
impact position, sa~.d hammer piston comprising a first
surface which alternately is connected to a liquid pressure
souxce and to a reduced pressure, whereby pressurization of
said. first surface drives the hammer piston toward the drill
tool, and a second Surface which during said movement to-
and-fro is continuously pressurized for loading the hammer
piston in a direction away from the drill. tool, wherein said
hammer piston comprises a channel and when the hammEr piston
moves past said impact position, said channel Conducts
pressure liquid to a valve body for sw~.tching aver and
lacking the valve body fax continuous pxessuxization of said
first surface for locking said hammer piston ir1 a fort~ard
position, wherein the forward position occurs when the
hammer piston extends further than the impact position
during upwaxd dulling and wherein said channel also
conducts pressure liquid to a flushing channel for
continuous flushing of a drzll hole.
An embodiment of the invention is described below
with reference to the accompanying drawings in wh~.ch fig 1
shows the middle part of a liquid driven dawn-the-hole
drilling machine with the hammer piston in impact position.
Fig 2 shows the front part of the liquid driven down-the-
hale dxilling machine with the hammer piston in impact
position. E'ig 3 shows the, middle part of the liquid driven
down-the-hole drilling machine with the hammer piston in
flushing position. Fig 9 shows the front part of the liquid
driven down-the-hole drilling machine with the hammer piston
in flushing position.

CA 02283447 1999-09-07
WO 98/41726 PCT/SE98/00447
2
The embodiment of the invention shown in the drawings is a liquid driven, e.g.
water
driven, down-the-hole drilling machine comprising a housing in form of a tube
1 and a
split lining 11,12,13 positioned therein and in which a hammer piston 2 is
movable
to-and-fro for exerting a drill tool 3 to impacts. The hammer piston is
journalled in
bearings 14,15 which can be made as shown in WO 96/19324. The drill tool 3,
which on
the front surface is provided with hard metal buttons 16, is connected to
housing 1 by
means of a splined coupling 17 and prevented from falling out of the housing 1
by a ring
18 which for mounting reasons is divided. An elastic sleeve 19 is arranged
about the
hammer piston 2 in order to prevent drill cuttings from ente~~ing into the
impact device at
upward drilling. At downward drilling the sleeve 19 prevents liquid in the
drill hole from
entering in to the impact device. In the rear part of the tube I a valve
housing 21,22,23
comprising a valve body 9 is arranged. Behind the valve housing there is a
usual, not
shown, threaded rear piece for connection to a drill tube string. The drill
tube string
transfers rotation from a rotary motor to the tube l and thus via the splined
coupling 17 to
the drill tool 3. Furthermore, driving liquid is supplied via the drill tube
string to the impact
device for driving this and for flushing the drill hole. In the drawings this
is marked by the
pressure source 5. The valve body 9 cooperates alternately with valve seats 24
and 25.
When the valve body is in the position shown in fig 1 pressure liquid is
supplied to a first
surface 4 on the hammer piston 2 from pressure source 5 and via a conduit 26,
here drawn
outside the machine, to a second surface 7 on the hammer piston 2. When the
valve body 9
is in its opposite end position the first surface 4 is via a connection 29
connected to a
reduced pressure in the flushing channel 6. The flushing channel 6 is
connected to the
flushing channels 31,32 in the drill tool 3. Surfaces 4 and 7 nre situated on
a part 28 of the
hammer piston 2 having a larger diameter than the rest of the hammer piston.
The pressure
on the second surface 7 during drilling continuously loads the hammer piston 2
in a
direction away from the drill tool 3. The hammer piston 2 is around its
periphery provided
with a number of channels 8 and a number of slots 27. With the position of the
hammer
piston 2 shown in fig 1 the room 33 at the valve body 9 is connected via
conduit 34,
channels 8 and connection 35 to flushing channel 6. Through this the pressure
in room 33
is lowered. Valve body 9 is displaced to cooperation with valve seat 25 by the
pressure in
the continuously pressurized room 36. The supply of pressure liquid to the
first surface 4 is
r r

CA 02283447 1999-09-07
WO 98/41726 PCT/SE98/00447
3
disconnected. The first surface 4 is instead connected to the reduced pressure
in the
flushing channel 6. The pressure on the second surface 7 then drives the
hammer piston 2
to the right in fig 1. When the hammer piston 2 has reached its right end
position slots 27
connect conduit 26 with conduit 34. Through this room 33 is pressurized so
that the valve
body 9 is displaced to the position shown in fig 1. The first surface 4 is
again supplied with
pressure liquid through which the hammer piston 2 makes a working stroke to
the impact
pOSit10I1 ShOWn Ill fig 1.
In figs 3 and 4 the impact device is shown in the position which the hammer
piston takes
when the feed force has ceased, e.g. through backing of the clown-the-hole
drilling machine
from the drill hole front. Since the drill tool 3 can be pushed out somewhat
from the
drilling machine by the pressure in chamber 41, which is hi~,her than the
pressure in the
drill hole, the hammer piston 2 passes the impact position, which is shown in
fig 1. At
upward drilling the movement past the impact position is assisted by the
action of the
hammer piston 2. When the hammer piston 2 reaches the position shown in fig 3
pressure
liquid is supplied from conduit 26 via the channels 8 to conduit 34. Through
this room 33
is pressurized so that the valve body is locked in the position shown in fig
3. Pressure
liquid is herewith supplied to the first surface 4 which through this pushes
the hammer
piston 2 to the left in fig 3 and locks it in this position. Because both the
first surface 4 and
the room 33 are pressurized the hammer piston remains in the shown position
until the
down-the-hole drilling machine again is fed toward the hole bottom so that
drilling is
resumed. In the position shown in fig 3 pressure liquid is supplied besides to
the valve
body 9 also via connection 35 to flushing channel 6 and from there to flushing
channels 31
and 32 in the drill tool 3.

Representative Drawing