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...Chester Carlson was a patent agent who tired of having to make multiple copies of patent applications using the only duplication method available at the time: carbon paper. In 1959 he came up with a new copying system and took it to IBM for evaluation. The "experts" at IBM determined potential sales to be only 5,000 units because people wouldn't want to use a bulky machine when they had carbon paper. Carlson's invention was the xerography process, the company founded on the system is Xerox.

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Class 219/61.6 - Using three or more electrodes


Subclass of Class 219 - Electric heating
Definition: Subject matter including the use of three or more electrodes
No. of patents: 4
Last issue date: 04/01/2008


NumberTitleIssue Date
7350386Method and apparatus for making tubes
In a method of making a tube, a sheet metal blank is placed in a U-shaped cavity of a lower mold of a shaping tool, and pressed into the cavity by a ram to shape the blank into a U-shaped configuration. In a next process step, the U-shaped blank is formed between an...
04/01/2008
7199325Method for interconnecting tubulars by forge welding
A method for interconnecting tubulars by forge welding involves arranging the tubular ends that are to be interconnected at a distance, up to a few millimeters from each other in a shield gas chamber, into which a reducing non-explosive flushing fluid mixture (e.g. ...
04/03/2007
4621181Method of manufacturing multilayer screw seam pipes and device for carrying out the method
An improved method of manufacturing multilayer helical seam pipes from strips or bands lying loosely over each other to prevent porous welding seams due to heated air escaping from resultant gaps between the layers of strips, comprising feeding the strips...
11/04/1986
4143801Multiple welding head system for fabricating pipe
A pipe is fabricated from rolls of flat metal plate by continuously moving the plate into a pipe-forming station which shapes the flat plate into a pipe having a longitudinal seam therealong. A plate arc welding machine welds consecutive plates to each ot...
03/13/1979
 
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