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WATER JET CONFERENCE - Waterjet Technology Association

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The drilling fixture is designed to permit testing of bits of up to 3 ft. in diameter.<br />

The drill pipe is fitted with an adapter plate onto which various types of drill bits can be<br />

mounted. Presently, the machine is fitted with a 28-inch diameter roadheader cutting head<br />

dressed with conical bits (Figure 6).<br />

Controls and Data Monitoring System<br />

The laboratory drilling fixture is equipped with various types of<br />

transducers to monitor and measure machine operative parameters. Presently,<br />

instrumentation is available for measuring thrust, torque, rpm, penetration rate, water-jet<br />

pressure and flow. Provisions have been made for expanding the number of data channels<br />

that can be measured as need arises.<br />

Machine thrust is measured with a pressure transducer installed on the thrust<br />

actuator hydraulic line. A similar type pressure transducer is also used for measuring the<br />

torque pressure supplied to the drive motor. Penetration rate measurement is<br />

accomplished with a 10-turn potentiometer mounted on one of the guide shoes. This<br />

potentiometer is calibrated to produce a certain voltage output for a given linear<br />

movement of the drive assembly with respect to the fixed base frame. A DC-generator<br />

type transducer is used to measure the rotational speed of the cutterhead.<br />

The drilling fixture is currently operated with manual hydraulic controls. A<br />

control panel located behind the machine in an elevated position contains all necessary<br />

controls and meters for the manual operation of the equipment. Data from all transducers<br />

is routed to a multi-channel light-beam recorder which features high frequency response<br />

and a wide selection of chart speeds.<br />

Future plans for the drill rig call for its totally automated operation using the<br />

commuter system that is currently available with the rotary cutting machine. This will<br />

permit electronic servo-control of drill rig operative parameters and enable high speed<br />

acquisition and analysis of data generated from testing. Thus, the main computer control<br />

system described earlier will incorporate the capability of running either one of the two<br />

machines.<br />

Design work is also underway for installing a 6-channel wireless telemetry unit on<br />

the drill rig. The system will be mounted on the center rotating tube which passes through<br />

the drive head. Selected bits on the cutterhead will be instrumented and data telemetered<br />

to recording devices in order to measure bit forces during rock cutting.<br />

Test Plans<br />

As noted previously, the drill rig is currently fitted with a 28 inch diameter<br />

roadheader cutting head equipped with conical bits. The system is being used as part of a<br />

research program sponsored by the Department of Energy to evaluate various cutting<br />

techniques for the mechanical mining of oil shale. This effort will primarily concentrate<br />

on conducting a series of tests to assess the applicability of roadheader type machines to<br />

cutting of oil shale. Included in the investigation will be the evaluation of obtainable<br />

362

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