Westinghouse Electric Corporation

Abb Power Td & Company

Richard A Miller

William H Kasner

Norman M Pavlik

John Sefko

Vincent A Toth

Gerald Joseph Bruck

Phillip J Hawkins

Michael Anthony Burke

Ralph W Kalkbrenner

Donald T Hackworth

Robert Duncan

Richard M Kobuck

George D Bucher

John S Kerrey

Larry M Kozak

Wesley G Pope

Gerald G Lessman

A weld pool viewing system including optical elements for enhancing the weld pool image is positioned at an angle relative to the axis of a welding torch to extract image information pertaining to the interface of the weld pool with a workpiece to control the welding parameters.

Weld pool viewing system

The wall of a pressure vessel tube having stress-corrosion cracks or the like is repaired by localized melting using laser welding, for fusing over defects by melting and re-solidifying the metal. A high powered laser beam is focused at a limited area or spot on the internal wall of the tube. The welding head is operated at sufficient power and is relatively moved in the tube at a sufficient rate to melt the spot while advancing along a line on the internal surface of the wall. The wall is melted to a depth of part or all of the thickness of the wall. Points at which the tube has been melted by the focused beam cool following passage of the welding head. The welding head is also advanced laterally of the line, either continuously or stepwise. Localized melting and cooling of the tube material continues progressively, line by overlapping and/or adjacent line, to melt and reform the degraded area. By successively melting, and optionally alloying linear sections of the wall using an alloying material, stress-corrosion cracks and similar defects are fused over, repairing the degraded area. The localization of the melting is such that the metal does not substantially flow and the metal cools quickly following passage of the weld head, to below a temperature of sensitization.

Direct tube repair by laser welding

A steel sheet (10) having a stress-relief annealed, structure with a plurality of magnetic domains (12) is made by drilling a plurality of closely spaced, small holes (15) through the entire thickness of the steel sheet, where the drilling is effective to form additional domain walls (17) and subdivide the magnetic domains.

Drilling of steel sheet

A laser welding head for welding a sleeve within a tube by fusing the interface between the sleeve and tube with a laser beam. The laser welding head has a cylindrical housing adapted to be inserted inside of the sleeve, a focusing lens for focusing a laser beam transmitted through the housing, and a welding mirror for directing the focused beam out of the housing and into contact with the sleeve. The welding mirror is maintained a predetermined distance from the inside surface of the sleeve and a motor and drive assembly are used to rotate the welding head within the sleeve. Shield gas is supplied to the welding head and passes about the periphery of the focusing lens for cooling the focusing lens and the welding mirror before being discharged into contact with the weld area. A recessed aperture is provided within the discharge outlet to prevent molten material from the weld site from splattering into the housing and onto the mirror or lens. Multiple pass welds are preferred for attaching each end of the sleeve to the tube with the preferred weld paths being either multiple discrete weld paths or continuous overlapping helical weld paths at each end of the sleeve.

Laser welding head for sleeve-to-tube welding

A method for welding a sleeve within a tube of a steam generator, the sleeve being in close contact with the tube. A welding head of a weld head apparatus is positioned within the tube at a predetermined weld site, a laser beam is directed to the welding head, the beam is focused with a focusing means, the focused laser beam is reflected with a welding mirror means into contact with a portion of the sleeve to be welded to the tube, the welding mirror means is maintained a predetermined focal distance from the inside surface of the sleeve, and the welding head is rotated to complete a weld fusion path about the inner periphery of the sleeve. Shielding gas is used to shield the weld site. A robotic arm positions the weld head apparatus within the steam generator. At each end of the sleeve, multiple discrete weld paths or a continuous helical multiple weld path are welded. The sleeve is preferably welded to the tube along the weld path with a fusion width at the interface between the sleeve and tube of at least 0.045 inches and the tube is penetrated to a depth of at least 0.25 inches. The laser delivers 500 to 700 watts to the weld area.

Laser welding of a sleeve within a tube

Apparatus is disclosed for aligning a laser beam used to perform laser machining operations. The aligning apparatus of this invention is used with laser machining apparatus comprising a laser for emitting a laser beam along a path and a laser lens assembly disposed within the path and movable along an axis for variably focusing the laser beam at a plurality of different focal spots corresponding to the plurality of laser machining operations. The alignment apparatus takes the form of an adjustable mirror, which is disposed to intercept the laser beam and to align at least a portion of the path with the axis of the laser lens assembly, whereby the lateral displacement of each of said plurality of focal spots from the axis is reduced as the laser focusing assembly is moved along its axis.

Beam alignment system for laser welding system

Apparatus and method for directing a controlled number of laser pulses onto a work piece to be machined. More specifically, the laser machining apparatus includes an excitable laser and an excitation lamp for continuously exciting the laser to emit a sequence of laser pulses. The application of the laser pulses to the work piece is controlled by an inner-cavity shutter that is opened to permit a precise number of pulses to be directed onto the work piece. The frequency (REP RATE) and pulse width of the laser pulses are controlled by the excitation lamp and, in turn, are set to create a progressive weld of significant depth and structural integrity. In particular there is provided control means for counting the number of laser pulses applied to a machining site of the work piece, whereby a known controllable quantity of energy is imparted to each site. To this end, the counting of the laser pulses begins after the completion of a laser pulse, whereby the actuation of the inner-cavity shutter is not synchronized to the computer but rather to the laser emission so that only whole laser pulses will be applied to the site.

Pulsed laser machining apparatus

A reduction in ferromagnetic domain size is obtained with equipment and processes being capable of the high speed laser scribing of ferromagnetic sheet material. The invention involves the elastic bending of sheet material around an axis which is parallel to the direction in which it is being translated and then laser scribing the curved sheet material. A rotating optical device is used to repeatedly send a focused laser beam across the width of the curved sheet material.

Apparatus and process for laser treating sheet material

Apparatus and method are disclosed for machining and, in particular, welding a work piece in an environment comprised of a gas non-reactive to the material of the work piece to minimize the contamination of the welds effected on the work piece. In an illustrative embodiment of this invention, there is provided a welding chamber for receiving the work piece and for establishing the welding environment therein. The welding chamber has an input port disposed in a bottom portion thereof, that is coupled to means in the form of a controllable pump for directing or pumping the non-reactive or inert gas, e.g. argon, through the input port and into the welding chamber. The welding chamber also includes an output port, whereby the non-reactive gas may escape from the welding chamber. A diffuser plate distributes the non-reactive gas substantially uniformly across the cross section of the welding chamber, whereby a laminar flow of the non-reactive gas is directed over the work piece and is permitted to escape through the output port.

Apparatus and method for laser machining in a non-reactive environment

Welding plates for laser beam welding of a fuel rod grid are provided, each welding plate having a surface with a set of equally spaced, parallel grooves and with a second set of such grooves perpendicular to the first set. Each of the welding plates is provided with openings therethrough at the points of intersection of the straps forming the grid, so as to expose those points of intersection to a laser beam for laser beam welding of the points of intersection. A vane side welding plate has the walls of the laser beam access openings placed so as to hold vanes extending from the straps in deflected position. Stand-off pins and clamping bolts are provided, the latter having heads with access openings for the laser beam. The welding plates are provided with protrusions which extend laterally thereof, the protrusions having precisely located holes with precision bushings therein.

Growing community of inventors

N. Huntingdon, PA, United States of America

Richard A Miller