Development of Small Diameter Drilling Machine for Ground Investigation (Mole Robot)
Outline of the Research
Since the law of countermeasures for contaminated soils was enforced in 2003, the needs of the soil investigation just below the building have been increasing. Takahashi laboratory is developing a small diameter drilling machine(mole robot) and micro-drilling system to realize the low cost and effective ground investigation.
Recent Research Topics
- (1) Development of Small Diameter Non-Discharged Type Drilling Machine
- (2) Development of Remote Controlled Type Drilling Machine
- (3) Development of a Mobile Type Small Diameter Drilling Machine
(1) Development of Small Diameter Non-Discharged Type Drilling Machine
When the contaminated soil just below the building is investigated, generally a large scale drilling machine such as horizontal drilling machine is carried to the drilling site and horizontal well is drilled under the building. However, sometimes it is easy to predict the contamination area such as the leakage from the solvent tank in the factory, and in this case, the use of large scale horizontal drilling machine is uneconomical and ineffectively. Therefore, we are developing the small diameter non-discharged drilling machine which can drill the pinpoint hole to the contamination area under the building, and are trying to increase the efficiency of the soil investigation under the building. We have already designed and manufactured a few drilling machines, but as it was found by the experiments that the smooth removal of cuttings(drilled soils) is very hard in small diameter drilling, we are developing a new drilling machine based on the screw concept. It was confirmed that the drilling without discharging the cuttings is possible by screw type drilling machine, and we are now measuring the necessary torque in drilling and are studying how to control the drilling direction.
Screw type drill head
The shape of drilled hole: This shape is obtained by pouring the gypsum solution into the hole.
The drilling experiment
Drilled hole
(2) Development of Remote Controlled Type Drilling Machine
The purpose of this study is the same as the one of above research. In this study, screw conveyor system is used for discharging the cuttings. In order to drill a pinpoint hole to the contaminated area, directional drilling is necessary. In this study, the directional drilling is allowed by connecting the crews by the universal joint as shown in the picture below. Now, we are studying the effects of screw pitch, the shape of the cutting tool etc. on the drilling speed. This method is applicable to the lunar drilling for ISRU(In-Situ Resources Utilization), We are now preparing to begin the cooperative research with JAXA and other universities.
Directional drilling machine
Universal Joint
Image of ISRU (from Mr. Jerry Sanders/NASA-JSC)
(3) Development of a Mobile Type Small Diameter Drilling Machine
In order to investigate the soil in a wide area, the drilling machine should be mobile and a mechanism of universal drilling is necessary. Therefore, we are also engaged on the development of universal drilling machine which can move in the soil under the building universally. The drilling machine shown in the picture below has an auger of one pitch in the front, and the cuttings excavated by auger is carried to the belt conveyor. Then, cuttings are transported through the inside of the machine and discharged from the end. The forward movement and reactive force in the moving direction are obtained by the crawler. In drilling by auger, the rotation moment also acts on the machine, but enough reactive force to resist this moment is not obtained as yet. Furthermore, the connection between the auger and belt conveyor is not well, and cuttings are not carried smoothly. Therefore, we are continuing the research to solve above problems.
Universal drilling machine(mole robot) manufactured in Takahashi laboratory. Further investigations are still necessary.