A piezoelectrically actuated percussive bit augments rotary drills to form a rotary-hammering drill/sampler. The Percussive Augmenter of Rotary Drills (PARoD) bit has two key modalities: one with vibrating free-mass and one without. In the first modality, the bit is designed to rotate the tip and transmit the impact of a free mass, while the complete bit turns as a single unit. In the second modality, the ultrasonic hammering action from the piezoelectric stack and the rotation from a commercial drill are applied directly to the drilled object. The PARoD tool includes slots to ensure that the tip of the bit does not rotate separately from the piezoelectric actuator. The bit employs electric and mechanical slip rings to transfer electric power, as well as water (for removal of cuttings and bit cooling), while freely turning the bit. The cooling plumbing can be connected to the related fixtures on heavy-duty commercial rotary drills.

The PARoD Tool as an ultrasonic bit with free mass. On the left is a cross-section showing the free mass and a preloaded spring using a dog-bone horn configuration. On the right is a solid model rendering showing the horn, spring, and free mass. The wedges are intended to make the horn rotate with the bit.
The percussive drill bit design was part of work done in developing the Ultrasonic/Sonic Gopher, through which it was determined that there is a need for a rotation mechanism to effectively remove the cuttings and rock-breaking to enhance drilling speed. The prior design of an integrated rotary-hammer drill was described in “Ultrasonic/Sonic Rotary-Hammer Drills” (NPO-44765), NASA Tech Briefs, Vol. 34, No. 7 (July 2010), page 41. The PARoD tool is shaped as a bit that is mounted onto commercial rotary drills and uses their power and cooling sources for the rotary actuation. The bit can be made in various diameters.

This work was done by Jack B. Aldrich, Yoseph Bar-Cohen, Stewart Sherrit, Mircea Badescu, Xiaoqi Bao, and James S. Scott of Caltech for NASA’s Jet Propulsion Laboratory.

In accordance with Public Law 96-517, the contractor has elected to retain title to this invention. Inquiries concerning rights for its commercial use should be addressed to:

Innovative Technology Assets Management
Mail Stop 202-233
4800 Oak Grove Drive
Pasadena, CA 91109-8099
E-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.

Refer to NPO-46550.

This Brief includes a Technical Support Package (TSP).
Document cover
Percussive Augmenter of Rotary Drills for Operation as a Rotary-Hammer Drill

(reference NPO-46550) is currently available for download from the TSP library.

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