File:Ultrasonic drill 1955.jpg

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DescriptionUltrasonic drill 1955.jpg	English: Model U600 ultrasonic drill, made by Vibro-Ceramics Corp., Metuchen, New Jersey in 1955. This could cut holes in glass, tungsten carbide, sapphire, ceramic, and hardened steel by ultrasonic machining, using a steel tool vibrating up and down at ultrasonic frequencies applied to the work with a slurry of abrasive. The power unit (right) produces an alternating current oscillating at ultrasonic frequency (above 20,000 Hz). This is applied to a piezoelectric ceramic transducer in the drill body (top) causing it to vibrate. The transducer is attached to an exponentially tapered steel rod (center) which acts as an acoustic "transformer" to increase the amplitude of the vibrations. The steel cutting tool is screwed to the lower end of the rod. A variety of interchangeable tools for cutting holes of various shapes and sizes come with the unit. The unit consumes 35 watts and weighs 15 lbs.
Date	March 1955
Source	Retrieved January 24, 2015 from Radio-Electronic Engineering magazine, Ziff-Davis Publishing Co., New York, Vol. 24, No. 3, March 1955 , p. 32 on http://www.americanradiohistory.com
Author	Unknown authorUnknown author
Permission (Reusing this file)	This 1955 issue of Radio-Electronic Engineering magazine would have the copyright renewed in 1983. Online page scans of the Catalog of Copyright Entries, published by the US Copyright Office can be found here. Search of the Renewals for Periodicals for 1978 and later show no renewal entries for Radio-Electronic Engineering. Therefore the copyright was not renewed and it is in the public domain.

Licensing

This work is in the public domain because it was published in the United States between 1929 and 1963, and although there may or may not have been a copyright notice, the copyright was not renewed. For further explanation, see Commons:Hirtle chart and the copyright renewal logs.
Note that it may still be copyrighted in jurisdictions that do not apply the rule of the shorter term for US works (depending on the date of the author's death), such as Canada (70 years p.m.a.), Mainland China (50 years p.m.a., not Hong Kong or Macao), Germany (70 years p.m.a.), Mexico (100 years p.m.a.), Switzerland (70 years p.m.a.), and other countries with individual treaties.

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