Note: Descriptions are shown in the official language in which they were submitted.
DRILLING EQUIPMENT
The present invention relates to pn~uma~ic drilling
equipment of the type comprising a drill bit and a dri-~-
ing device therefor having a pneumatically operated
sinker drill machinery. With this type of equipment,
considerable difficulties are encountered in that water,
sand and clay in the drill hole may flow bacXwards up
through the drill bit and into the sinker drill machiner-~,
as a result of which drilling must frequently be discon-
tinued and the sinker drill machinery cleaned. To coun-
1~ teract such inflow of water, sand and clay, it has beentried to mount nonreturn valves in the air supply duct
supplying air to and removing air from the pneumatically
operated sinker drill machinery. Known conventional
non-return valves for this purpose have been bulky and,
from considerations of space and also for functional
reasons, had to be placed in the air supply duct ahead
of the air inlet to the sinker drill machinery. These
known non-return valves have entailed some improvement,
but have been unable completely to stop penetration of
water, sand and clay into the sinker drill machinery.
Furthermore~ ln additisn to being bulky, the known non-
return valves are design~d in an expensive manner.
With the present i~ven~ion, it has now been found
possible to position the non return valve in the air
supply duct between the sinker drill machinery and the
drill bit, provided that a special non-re-turn valve is
- used. Accordiny to the inven ion, the non-return valve
should be in the form of a dome-shaped valve member
consisting of elastomer materlal and having its convex
side facing in the direction of the air flow, said valve
member brid~ing the air supply duct and having through-
flow slots adapted to open when compressed air is sup-
plied through the sinkPr drill machinery and to close
again when t~e compressed alr supply is discontinued.
The dome-shaped valve mPmber preferably is conical on
its outer side and preferably also on its inner si-3e,
The throughflow slots in the ~ome-shaped ~Jalve memb~r
preferably have apertures which, if the dome-shape~
valve member is viewed from its convex side, ext2nd
crosswise across said valve member. It was found that
the best result is obtained if the intersecting through-
flow slots intersect one another slightly offset in
relation to the top of the dome-shaped valve member.
In this manner, the throughflow slots will ext~nd like
chords across the dome-shaped valve member~ The through-
flow slo s preferably are provided by cutting the dome-
shaped valve member without any substantial removal
of material, whereby the non-return valve will obtain
high sealing capacity when it is to prevent water, sand
and clay from penetrating backwards through thé air
su~ply duct. ?
Swedish patent specification 7709894 5 (413,929)
discloses an injector which is utilised for injecting
material through drill holes or other holes in rock
or other solid material. This injector is provided at
its outer end with a detachable injector nozzle in the
form of a non-return valve, and an expandable expander
for sealing against the wall of ~he hole in which the
injector is inserted. In one of its embodiments, the
injector nozzle i5 formed with a dome-shaped valve por-
tion consisting of elastomer material and bridging the
end of the injector pipe, The injector nozzle has through-
flow slots adapted to open upon injection of the seal-
ing material under pressure through ~he injector pipeand to close again when the pressure of the sealing
material in the injector pipe is relieved. This prior
art injector is intended for the injec~ion of cement
or other stabilising compounds or for static position-
ing in a drill hole. It must be regarded as surprisingthat the difficulties encountered with dynamic sinker
drill machineries and drill bits associated therewith
can be eliminated by using the dome-shapcd non-re~u-.n
valve previously known in and per s~ in con~unc~ion
with the inj~ctor.
An embodiment of the drilling equipment a~cording
to the invention will be described in more ~etail ~Delowl
reference being had to the accompan~ing dra~Jing in r,7hich
Fig. 1 illustrates an embodiment of a drilling
equipment designed in accordance with the present inven-
tion;
Fig. 2 illustrates~ partly in section, a drill
bit comprised by the equipment;
Fig~ 3 is a vertical section through a non-return
valve in the equipment according to the invention; and
Fig, 4 is a plan view of the non return valve,
seen from the tip endO
The drilling equipment illustrated in Fig; 1 is
an example of different drilli~g e~uipments that may
be designed in accordance with this invention~ The em-
bodiment illustr~ted comprises a flushing head 11, a
drill pipe 12~ a liner pipe 13, a winged sleeve 14,
a sinker drill machinery 15, a bit pipe 16, a guide 17,
a reamer 18 and a pilot bit 19. The equipment is such
that the pilot bit 19 and the reamer 18 together drill
a hole having the same or a slightly larger diameter
than the liner pipe 13. Furthermore~ the equipment is
such that all components can be pulled up through the
liner pipe 13 which may remain in the drill hole. The
sinker drill machinery 15 of the equipment is operated
by compressed air which is supplied down to ~he sinker
drill machinery through the drill pipe 17, and the air
leaving the sinker drill machinery is discharged through
a central hole in the pilot bit, In known drilling equip-
ment of this type~ a non-re~urn valve has been mounted
in the air supply duct at the transition between the
sinker drill machinery 15 and the winged sleeve 14.
According to the present invention, however, a
non-return valve 20 is positioned in the air supply
duct 21 between the tip of the drill bit 19 and th~
sinker drill machinery 15. As will appear from Fig. 2,
the non-return valve has been positioned in a r"idened
portion of the air supply duct, such that the non-return
valve supports itself against a shoulder 22. In ~his
manner, the non-return valve will be completely enclosed
by the pilot drill bit which thus can be mounted in
normal manner in the rest of the drilling equipment
and without necessitating further modification thereof.
In the em~odiment illustrated9 the pilot drill b_t is
mounted by means of a large thread 230
In the embodiment illustrated, the non-return valve
20 has an outer metal ring 24 which is vulcanised to
a conical ~lastomer body 25 extending in the manner
of a dome out of the metal ring. In the embodiment il-
lustrated, the elastomer body is conical, its conical
outer side having a slightly ~aller top rake than its
conical inner side9 whereby the thickness of the ela-
stomer ~aterial will be slightly smaller at the tip
end of the conical elastomer body than at the base end
thereof~ adjacent the metal ring 24. By this design,
functional advantages are obtained.
In the embodiment of the non-return valve illustrat-
ed in Figs. 3 and 4, two intersecting cuts 26 have been
made in the conical elastomer body. These cuts extend
practically all the way down to the metal ring 24 and
have been formed without any appreciable removal of
material. In this manner, the non-return valve will
obtain high sealing capacity. In the embodiment illu-
strated, the intersection of the two cuts has been placedeccentrically in relation to the tip of the conical
elastomer body, as indicated by two diametrical lines
in Fig. 4, whereby an improved sealing capacity of the
non-return valve is obtained. The four lips 27 which
are formed by the ~wo cuts 26, will act as sealing lips
that are moved apart under the action of th~ compressed
~"f' air flowing down from the sinker drill machinery 15
towards the tip of the drill bit 19. hs soon as the
supply of compressed air ceases, the four lips 27, ~e-
cause of their elasticity, will return into their seal-
ing initial po~ition, as sho~m in Figs. 3 and 4. If
water, sand or clay should tend to flow upwards tnrougn
the air supply duct 21, after the supply of compressed
air through said duct has been discontinued, the "a~er,
clay or sand will press against the four lips 27 which
thus will be compressed together even more, thereby
increasing the sealing capacity upon an increasing back
pressure in the drilling equipment.
The dome-shaped non-return valve described above
may have the cuts 2~ positioned in a different manner,
for example along chords of the elastomer body, if this
should be desired. It is also possible to use other
dome shap~s than the conical shape illustrated in the
drawing. However, care must be'taken that the capacity
of the non~return valve to prevent backflow or fluid,
such as w~ter t sand and clay, increases upon an increase
in pressure, and that the non-return valve will have
good opening capasity upon supply of compressed air
to and through the sinker drill machinery.
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