Method of using a pressurized medium in drilling

A method of using an organic, oil-based pressurized medium derived from natural biological metabolism for the percussion device in a drilling device of a drilling apparatus having a drilling bit at its one end for drilling a hole in the ground comprises: a) causing the organic oil-based pressurized medium derived from natural biological metabolism to flow in the drilling hole through at least the drilling device and possibly one or several drill rods, when joined to the drilling device for increasing the drilling depth of the drilling device, b) driving the percussion device for generating the percussion movement by the organic oil-based pressurized medium derived from natural biological metabolism supplied through a first flow channel provided in the drilling device and the drill rod, c) removing drilling waste generated by the drilling bit at the end of the drilling device by a scavenging agent supplied through a second flow channel provided in connection with the drilling device and the drill rod, and d) supporting the drilling apparatus with a support frame being at least indirectly supported by the ground.

FIELD OF THE INVENTION 
The invention relates to a method of using a pressurized medium for the 
percussion means in a drilling device of a drilling apparatus for drilling 
a hole in the ground. 
BACKGROUND OF THE INVENTION 
Drilling apparatuses using pressurized medium have been know for a long 
time in the mineral industry, and they comprise: a drilling device, such 
as a down-the-hole drill or the like, the first end thereof having a 
drilling means, such as a drill bit, or the like, and the second end of 
the preferably connectable with one or several drill rods for increasing 
the drilling depth of the drilling device. The drilling device is at least 
partially arranged to be driven by a to-and-fro or corresponding 
percussion movement and comprises at least percussion means for generating 
the percussion movement driven by a pressurized liquid medium supplied 
through a first flow channel, Such drilling apparatus further preferably 
include scavenging means for removing drilling waste generated by the 
effect of the drilling means, the scavenging means supplying a scavenging 
agent through a second flow channel preferably in connection with the 
drilling means of the drilling device, and a support frame being at least 
indirectly supported by the ground. 
Apparatuses of the type described above, using pressurized air, have been 
widely used in mineral industry for a long time. It is an advantage of a 
drilling device which is to be placed down the hole that the percussion 
impact is directed to the drill bit, whereby the energy losses and 
unnecessary wearing of the components of the apparatus can be reduced in 
comparison with solutions having the drilling device placed at the rear 
end of drilling rods. Conventionally in drilling devices driven by 
pressurized air, pressurized air is used also for scavenging the crushed 
aggregate. However, it is not advantageous to drive a drilling device by 
pressurized air, because answer other thing this requires a compressor 
unit with a very high capacity. Furthermore, the efficiency of a pneumatic 
system is clearly lower than that of a hydraulic system. 
The use of a hydraulic drilling machine is known, for example from the 
published international application PCT/EP89/00256. In the solution of the 
above application, the driving unit of the drill rod, driven by a 
pressurized medium, conveys a to-and-fro rotational motion to the drill 
rod, as distinguished from the rotational motion conventionally used. 
Thus, hoses are arranged between the drill rod and the walls of the drill 
hole, and upon inserting or removing rods, hoses are fed into the hole or 
reeled in from the hole. To achieve an optimal drilling efficiency and 
save the hoses, the angle of rotation of the drill rod is preferably 
limited to the range of 180.degree.-360.degree.. For minimize the wearing 
of the hoses, an embodiment is presented in the publication where the 
drill rod comprises two outwardly open longitudinal channels in which the 
hoses are inserted for feeding in and out the pressurized oil of the 
drilling machine to be placed in the hole. The hydraulic hoses are o thus 
preferably inside the circle of the drill rod. Scavenging air is 
preferably delivered through a hollow drill rod. 
The solution described in the above-mentioned publication is not very 
practical, because massive machinery is required for the handling of 
hoses. Both hoses must be provided with reeling rolls and driving units, 
their need of space being determined by the depth of the hole to be 
drilled. It is difficult to handle the hoses in the drilling situation, 
and careless installation may result in environmental damage in case of 
damage to the hoses. Also, hoses of different lengths must be used or they 
must be fitted with joints when holes of different lengths are drilled, 
which results in further environmental risks. 
SUMMARY OF THE INVENTION 
The method of using pressurized medium according to this invention is 
intended to eliminate the disadvantages described above and thus to 
improve substantially the state of art in the field. For achieving this 
aim, the invention is primarily characterized in that the pressurized 
medium used is an organic, oil-based pressurized medium derived from a 
natural biological metabolism, such as a vegetable oil, an animal oil, or 
the like. 
Although, the use of vegetable or animal oils in drilling is previously 
known, the oils of the present type have not been previously used as a 
hydraulic fluid in any kind of drilling and thus naturally not 
particularly as the pressurized medium of the percussion means either. For 
example in the U.S. Pat. No. 4,631,136 and in the GB application 
2,246,802, vegetable and animal oils have been used in drilling as a 
scavenging agent only. 
Further, the use of vegetable oils as a hydraulic fluid has been studied 
and developed for a long time, articles on this being found from as early 
as 1983 and 1984. However, for almost ten years, no artisan in the field 
has been able to apply the use of an organic pressurized medium 
particularly in down-the-hole drilling of this context, or the like. 
The most important advantages of the use of the pressurized medium 
according to the invention are its simplicity and safety, which are 
essential requirements for working in both technically advantageous and 
environmentally safe way. The invention makes it possible to feed the 
pressurized medium in an integrated way through the drill rods, further 
facilitating the quick and easy insertion and removal of drill rods 
whereby it is also possible to use the continuous rotational movement of 
the drilling device in one direction. Consequently, the use of the 
pressurized medium according to the invention provides an advantageous 
technical application, whereby the operation of the drilling device is 
further optimized in an environmentally safe way.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S) 
FIG. 1 shows an advantageous application of the drilling apparatus using 
the pressurized medium of the present invention. The drilling apparatus 
comprises a drilling device 1, such as a down-the-hole drill or the like, 
the first end thereof having a drilling means, such as a drill bit 2; 
scavenging means 8 for removing drilling waste generated by the drilling 
means 2; and a support frame 9 which is at least indirectly supported, on 
the ground and fitted with feeding means 10a for providing the feeding 
movement of the drilling device 1 and with motion means 10b for providing 
the rotational movement or the like of the drilling device 1. The drilling 
device 1 is driven by a feeding movement in the direction of its 
longitudinal axis k and by a to-and-fro or corresponding percussion 
movement as well as by a rotational movement or the like in relation to 
its longitudinal axis k. The percussion means 6 of the drilling apparatus 
for providing the percussion movement of the drilling device 1 are 
hydraulically operated by an organic, oil-based pressurized medium m 
derived from a natural biological metabolism, such as a vegetable oil, an 
animal oil, or the like. 
The second end of the drilling device 1 is connected by joining means 3 
with a separate drill rod 4 for increasing the drilling depth of the 
drilling device 1 in the direction of the longitudinal axis k. Further, 
the drilling apparatus comprises a first flow channel 5 for supplying 
hydraulic fluid m and a second flow channel 7 for supplying scavenging 
agent 1 to the drill bit 2 functioning as the drilling means of the 
drilling device 1. 
Using a biodegradable pressurized medium according to the present 
invention, it is possible to supply the pressurized medium to the 
percussion means through a flowing space integrated in the drill rod. In 
the use of conventional hydraulic oils, this kind of a solution is not 
particularly advantageous nor even allowed in all conditions, because 
possible leaks cause immediate problems, such as contamination of the 
environment. Thus in the applications shown in FIGS. 1-4, the first flow 
channel 5 and the second flow channel 7 are arranged substantially in 
connection with the drilling device 1 and the one illustrated drill rod 4 
to provide for the movement of the drilling device 1 in the drilled hole. 
The drilling device 1 is thus moved preferably by the motion means 10b in 
a continuous rotational movement w in one direction. 
The second flow channel 7 comprises a flowing cavity 7a integrally arranged 
with the drilling device 1 and the drill rod 4. Thus, the first flow 
channel 5 comprises in a corresponding manner preferably two flowing 
cavities 5a1, 5a2 preferably integrally arranged with the drilling device 
1 and the drill rod 4. 
FIGS. 2 and 3 illustrate the joining means 3 connecting the drilling device 
1 and the drill rod 4, as well as the function thereof. The joining means 
3 are formed by a threaded coupling, and the first flow channel 5 and the 
second flow arrangement 7 are arranged as flowing cavities 5a1, 5a2, 7a on 
top of each other in the drilling device 1 and the drill rod 4 in the 
radial direction. Further, the joining means 3 comprise coupling means 3a 
which close the connecting units 5y1, 5y2 that are opened when the parts 
1, 4 are disconnected. Upon disconnecting the parts, it is thus possible 
to keep the hydraulic fluid m inside the parts which, in principle, 
function as deposits. When the parts are reconnected, the hydraulic fluid 
is immediately available for use by the drilling device. Before 
disconnecting the parts, they can be emptied from the hydraulic fluid, for 
example by pressurized air or in a corresponding manner. Thus upon 
reconnecting the parts, it is, however, necessary to feed the hydraulic 
fluid before the actual use of the drilling device. 
As shown in FIG. 4, the flowing cavity 7a for scavenging agent 1 is 
arranged on the perimeter of the parts 1, 4 to surround the first flow 
cavity 5a1 arranged centrally for the hydraulic fluid m and the second 
flow cavity 5a2 surrounding the same. 
As shown in FIGS. 2 and 3 in more detail, the coupling means 3a are 
self-operated by spring suspension f in connection with one end of the 
drilling device 1 and both ends of the drill rod 4 upon connecting and 
disconnecting the parts 1, 4, whereby the coupling means 3a are formed by 
counterparts to be placed within each other (FIG. 2). One of the fitted 
parts has a recess 3a1 and the other has a projection 3a2. Thus the 
corresponding flow cavities 5a1, 5a2 of the parts 1, 4 are connected with 
each other by flow units 3b1, 3a2 in the counterparts 3a1, 3a2. Further, 
the counterparts 3a1, 3a2 of the coupling means 3a are provided with 
closing parts, whereby one of the counterparts has a slide part 3c1 and 
the other has a socket part 3c2 at the end. Thus in the parts separated 
from each other (FIG. 3), the joint units 5y1, 5y2 of the flow cavities 
5a1, 5 a2 containing the hydraulic fluid m are closed by the closing parts 
3c1, 3c2. 
In an advantageous application, the pressurized medium m is an organic 
medium, such as rape-oil-based, hydraulic fluid or the like. 
As a result of continuous development, it has further been found that an 
advantageous; pressurized medium is a hydraulic fluid based on a vegetable 
oil ester; an example of this is a synthetic ethyl ester. 
It is clear that the present invention is not limited to the applications 
described above but that it can be varied within the idea even to a great 
extent. First, the hydraulic fluid of the percussion means can be supplied 
by hoses or the like. Correspondingly, one of the flow arrangements of the 
scavenging means can be formed of, for example two channels, one for 
supplying the scavenging agent and the other for suction through the inner 
space of the drilling device and the drill rod. In a corresponding manner, 
the rotational movement of the drilling apparatus can be arranged to and 
fro, although this requires more complicated and insecure control 
engineering than the solution presented above.