The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Sep. 07, 1999
Filed:
Nov. 17, 1997
Gary L Neiheisel, Cincinnati, OH (US);
Other;
Abstract
The invention relates to an apparatus for using laser radiation to remove an oxide layer (scale) by vaporization from a hot rolled or annealed steel strip (40) traveling in a gravitationally vertical direction at a speed of at least 10 m/min. The apparatus includes a high power laser such as a free electron laser and a sealed interaction chamber (90) containing a non-oxidizing gas (108). The electromagnetic radiation from the laser has a surface power density of at least about 5 MW/cm.sup.2 at a point of contact with the metal strip surface. The radiation is passed through an optical system of aligned lenses or mirrors for focusing the radiation into a straight line projected transversely completely across the strip. The radiation has a pulse width less than 100 picoseconds, a pulse repetition rate greater than 10 MHz and a high average power of at least 10 kW. A radiation beam (56) is passed through a homogenizer (60) having a linear diverging lens (74) for spreading the radiation in a linear transverse direction. The radiation is passed through a cylindrical convergent lens (78) or a long cylindrical mirror (132) and focused into a straight line beam (36) projected completely across the width of the strip. The oxidized strip passes into the sealed chamber through a slotted entry (91) and exits the sealed chamber through a slotted exit (92). The sealed chamber includes at least one elongated window (93) for receiving the radiation, an exhaust duct (94) for removing the non-oxidizing gas ladened with oxide debris from the chamber and a filter (106) for removing oxide powder from the gas. The non-oxidizing gas is directed into the chamber at a point just above a plasma plume (112) and just beyond incident focused radiation beam (36) through a long slot-like gas nozzle (114). By keeping the chamber sealed from the ambient atmosphere and maintaining sufficient non-oxidizing gas adjacent to the plasma interaction zone and the cleaned metal surface, reoxidation of the cleaned steel surface can be prevented.