Scientists at NASA’s Jet Propulsion Laboratory have developed a palm-sized ultrasonic drill that is powered by a flashlight battery and capable of drilling and coring hard rocks.
It’s thought that this invention, designed to collect rock samples from distant planets and asteroids, may also end up in the hands of craftsmen and surgeons.
Developed with engineers from Pennsylvania-based Cybersonics Inc, the device is driven by piezoelectric actuators which have only two moving parts and gears or motors. Piezoelectrics are materials that change their shape under the application of an electrical field.
The piezoelectric material excites ultrasonic and sonic vibrations which are responsible for the drilling action, forcing the drill bit to go up and down. The impact of the bit into the rock performs the drilling.Dr Yoseph Bar-Cohen, who is heading up the project, dismisses doubts about the lifetime of the drill. The actuator, which consists of a stack of piezoelectric wafers, is driven under compression and the strain involved is around the level of 3%. This stack is not, says Dr Bar-Cohen, subject to wear.
He also adds that because of the size and robustness of the drill bit itself it doesn’t need to be sharp, and therefore wear of the drill bit does not affect drilling performance.
The drill can, say researchers, easily be adapted to operations in a range of temperatures and, unlike conventional rotary drills, can core rocks like granite and basalt, without significant weight on the bit.
The demonstration unit weighs roughly 0.7kg and can drill 12mm holes in granite using less than 10W of power. To match this performance, a rotary drill requires around 20 to 30 times greater pushing force and more than three times the power.
The drill/coring bit does not require sharpening and its drilling speed does not decrease with time. There is no drill chatter and no drill `walk’ on start-up.
Commenting on the technology, Dr Bar-Cohen said, `besides the immediate benefits of the technology to NASA, it is paving the way for other unique ultrasonic mechanisms that are being developed in our laboratory and elsewhere. Such devices can be made to be small and lightweight, to consume little power and to exhibit a high standard of reliability.’
Tom Peterson, president of Cybersonics Inc, which holds a patent for the Drill added, `There are numerous commercial applications, especially in the medical field’.
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