Abstract:
The surface of an article, such as a glass envelope for an electric lamp, is provided with a decorative pattern or indicia by coating the article with a vitreous material that includes a substance (such as lead oxide) that undergoes a permanent change in color when heated under reducing conditions, subjecting the article to a laser beam and a reducing gas flame, and varying the position of the article relative to the beam at a speed and in a manner such that the beam scans the article and thereby melts preselected portions of the vitreous coating and changes the color of such portions. In the case of a vitreous or ceramic article that is susceptible to thermally-induced fracturing, the vitreous coating material is preferably deposited on the article in the form of a frit and the article is preheated to a temperature which is near or above its strain point, thus fusing the frit in place just before the glazed heated article is exposed to the reducing environment and laser beam. An apparatus and method for concurrently firing a glass frit on an article and color-etching the resulting glazed article with a laser having control means which includes a prototype article are also disclosed.
Abstract:
An indicia or artistic pattern, etc. is sculptured into the surface of an article, such as a glass envelope for an electric lamp or the like, by subjecting the article to a laser or an electron beam and varying the position of the article relative to the beam at a speed and in a manner such that the beam scans the article and removes preselected surface portions thereof either by vaporization or by thermally-induced fracturing and spalling. In the case of vitreous or ceramic articles that are susceptible to thermally-induced fracturing, etching by vaporization is achieved by preheating the article to a temperature which is near or above the strain point of the material. The sculpturing is preferably programmed by pulse-operating a laser with a control means which includes a photocell that scans a prototype article having the desired indicia or pattern on its surface. Apparatus for automatically reproducing a pattern or indicia in the surface of an article utilizing a laser source, a prototype article, means for correlating the movement of the prototype article and the article being processed relative to the laser beam and a photocell, and means for maintaining the laser beam in focused relationship with the surface of the article when the latter is of non-planar configuration is also disclosed. Novel decorative effects in the case of glass lamp bulbs are achieved by laser-etching the desired pattern in a coating applied to the exterior surface of the bulb and by subjecting a bulb to a series of laser pulses which produce a plurality of spaced cavities in the bulb surface by thermally-induced spalling and give it a pleasing facet-like appearance.
Abstract:
The tangling of helically coiled wire articles during bulk handling and shipment is prevented by providing integral nodules or beads of fused metal at each end of the articles which enclose the severed ends of the wire. In the case of tungsten wire coils that are designed for use in electric lamps and similar devices and are wound on iron mandrels, the fused beads are composed of tungsten-iron alloy and are formed in situ during coil manufacture by melting the ends of the mandrel with a source of concentrated heat, such as a laser, focused electron beam, plasma torch, or oxy-hydrogen flame. The tungsten-iron alloy beads remain on the end turns of the coil during the subsequent mandrel-dissolving operation, are ductile and are formed without embrittling the tungsten wire. Apparatus for manufacturing such beaded-end coils on a mass production basis using a continuous mandrel-coil stock wire and a laser is disclosed.