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.

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.

Abstract: A method for butt welding metallic sheets along a relatively long common seam line by providing a plurality of laser welding devices aligned above the common seam line, and effectively spaced from one another along a longitudinal axis. In a preferred embodiment, each welding device is independently adjustable in a direction parallel to a transverse axis which is perpendicular to the longitudinal axis. The metallic sheets are aligned on the upper surface in abutting relationship along the seam line and clamped for welding. Each laser welds only a portion of the sheets along the seam line, and the length of the relative movement between the welding devices and the sheets is greater than the effective spacing distance between welding devices to insure that a continuous weld bead is provided along the common seam line.

Abstract: A continuous wave laser light beam is directed at the refractory lining within a furnace vessel, and the displacement as measured by a self-scanned linear array of the scattered light beam from a nominal or reference position measured to provide an indication of lining wear or damage. The video signal received by the linear array receiver provides information for mapping the worn or damaged areas of the vessel lining so that such areas may be repaired by a gunning spray nozzle. The inspection apparatus includes an optical filter which is temperature controlled to prevent wavelength shifts away from the nominal laser wavelength. The electronic processing circuitry includes a voltage controlled oscillator responsive to the average background level for modifying the scan rate of the linear array to compensate for changes in background level. The threshold against which the reflected laser beam video signal is compared is also a function of background level.

Abstract: Portable inspection apparatus for determining the actual remaining thickness of the lining of a BOF vessel. The apparatus is mounted on a portable cart which can be wheeled into close proximity with the open top of a horizontally disposed furnace vessel. A laser transmitter directs a laser light beam toward the furnace lining. The light beam scattered from the vessel lining is received by a self-scanned linear array and correlated by means of a computer to provide a graphical representation of actual remaining lining thickness.Pneumatically operated locating members cooperate with positioning pads in the floor adjacent the vessel to accurately and repeatably position the cart with respect to the furnace coordinates. The inspection apparatus is also provided with computer processing to automatically scan a preselected area of the vessel lining less than the entire area in order to monitor lining locations of high potential wear.

Abstract: Apparatus and method for aligning a welding device along the center of a gap defined by confronting edges of at least two workpieces to be joined, wherein relative motion between the welding device and the workpiece gap occurs along a longitudinal axis substantially parallel to the gap such that the proximal edges of the workpieces can be joined by forming a weld seam along the gap during the relative motion. The apparatus preferably includes an imaging system for determining the location of the gap center relative to a predetermined two dimensional coordinate system by monitoring an image of a vision area along the gap downstream of the welding zone. In a preferred embodiment, the imaging system is effectively isolated from the welding zone through use of a high magnification optics system, a shroud structure, an independent light source, and a vectored jet of inert gas supplied to the welding zone.

Abstract: There is provided a method and device for automatically aligning the proximal edges of two or more appreciably magnetic sheets to be connected along abutting edges. The device preferably includes supports to align the magnetic sheets in substantially planar relationship aligned relative one another with their proximal edges oriented in approximately abutting relationship and generally aligned along a predetermined contiguous seam line. At least one of the sheets is to remain moveable on the supports relative to the other sheets. The alignment device further preferably includes an electromagnetic mechanism for simultaneously creating an effective north pole along the proximal edge of one of the supported sheets, and an effective south pole along the confronting proximal edge of the other sheet. These opposing poles cause a magnetic attraction between the proximal edges of the sheets which automatically pulls and aligns the proximal edges into intimate contact along their length.

Abstract: Portable inspection apparatus for determining the actual remaining thickness of the lining of a BOF vessel. The apparatus is mounted on a portable cart which can be wheeled into close proximity with the open top of a horizontally disposed furnace vessel. A laser transmitter directs a laser light beam toward the furnace lining. The light beam scattered from the vessel lining is received by a self-scanned linear array and correlated by means of a computer to provide a graphical representation of actual remaining lining thickness.Pneumatically operated locating members cooperate with positioning pads in the floor adjacent the vessel to accurately and repeatably position the cart with respect to the furnace coordinates. The inspection apparatus is also provided with computer processing to automatically scan a preselected area of the vessel lining less than the entire area in order to monitor lining locations of high potential wear.

Abstract: A continuous wave laser light beam is directed at the refractory lining within a furnace vessel, and the displacement as measured by a self-scanned linear array of the scattered light beam from a nominal or reference position measured to provide an indication of lining wear or damage. The video signal received by the linear array receiver provides information for mapping the worn or damaged areas of the vessel lining so that such areas may be repaired by a gunning spray nozzle. The inspection apparatus includes an optical filter which is temperature controlled to prevent wavelength shifts away from the nominal laser wavelength. The electronic processing circuitry includes a voltage controlled oscillator responsive to the average background level for modifying the scan rate of the linear array to compensate for changes in background level. The threshold against which the reflected laser beam video signal is compared is also a function of background level.

Abstract: Apparatus for scanning a continuous wave Nd:YAG laser beam across a moving strip of grain oriented silicon steel having an insulative coating to subdivide the magnetic domains of the strip to improve core loss without damage to the insulative coating. The laser beam is scanned by a multiple-faced rotating mirror and focused onto the strip surface by a flat field lens and cylindrical lens to produce a scan line of narrow width having the required irradiation energy, dwell time and line spacing at the surface of the moving strip.

Abstract: A process is taught for improving the core loss of magnetic materials of the type having a plurality of magnetic domains and an insulative coating thereon. The insulative coating may be a mill glass, an applied coating, or both. The magnetic material is scanned by the beam of a laser across its rolling direction so as to subdivide the magnetic domains without damage to the insulative coating.

Abstract: Automatic defect detecting inspection apparatus for detecting defects or imperfections contained in or on a moving slab or strip. The defect detection apparatus utilizes a linear light source for illuminating a selected portion of the slab or sheet surface and an array of optically sensitive elements arranged in side-by-side relationship to scan the surface of the sheet or slab in a direction transverse to the direction of movement to produce an output video signals corresponding to the optical intensity of the area scanned. An anamorphic optical system comprising spaced cylindrical lenses forming a Galilean telescope positioned between the moving material and the optically sensitive elements increases the sensitivity of the optically sensitive elements in the direction of the material movement while maintaining the sensitivity of the optical elements substantially unchanged in the direction transverse to the material movement.