Upload
dwight-maxwell
View
224
Download
0
Tags:
Embed Size (px)
Citation preview
Modelling and Experimental Validation of a Novel Ultrasonic Planetary Core
Drill (UPCD) Tool Design
X.Li, A.Bolhovitins, R.Timoney, P.Harkness, M.LucasUniversity of Glasgow, UK
1st Space Glasgow Research Conference, Glasgow, UK, 28 October, 2014
Background
SELEX GALILEO – ExoMars Mission
Conventional Driller/Corer
NASA – Jet Propulsion Laboratory (JPL)
Ultrasonic/Sonic Driller/Corer (USDC) operated from the Sojourner platform
Background
Compared with conventional drilling/coring, USDC has the following advantages:
UoG/MP Drill in Tenerife 2011
Light-weighted, compact, low pre-load, low power
Operate with a minimum axial load and holding torque which is suitable for low gravity environments
Operate at extreme temperatures
Avoid drill bit jamming, breaking, dulling etc
Capable of drilling a wide range of rocks
• The chaotic motion of the free mass create stress which propagates through the drill stems to the rock surface, rock fractures once stress exceeds the compressive limit
• Due to piezoelectric effect, piezoceramic rings convert high frequency voltage into ultrasonic vibration at the transducer base, and the level is adjustable depending on the power consumption.
• The ultrasonic transducer assembly drives a free flying mass which bounces between the horn tip and the base of drill stems at sonic frequencies.
UPCD Mechanism
• A tapered horn is used to amplify the vibration and ensure a considerable level of vibration at the horn tip
• Three drill stems will be used with each length 10cm. UPCD assembly target mass is 7kg, target power consumption 40W.
Conclusions
A novel driller/corer device has been developed with the USDC mechanism however employs two compression springs for different purposes
Dynamics of the UPCD process has been modelled and analysed, compression spring rates are optimized which delivers the maximum effective impulse from the drill to the rock
Experiments with dual springs are currently being performed which allows to validate the simulation results
A 1/2 wavelength ultrasonic transducer has been designed to decrease the weight and length of the UPCD assembly