Abstract: The invention relates to the tempering of sheets of glass and optionally their bending by the so-called contact process. It proposes a process in which the edge stresses of the glass sheets are reinforced by cooling the edges of the glass sheets in relation to their central zone, particularly by blowing on these edges with a cooling gas. It also proposes a device to perform this preferred cooling of the edges, as well as glass sheets thus tempered. The invention applies to the production of glazings having nonfragile edges, particularly for the automobile.

Abstract: Ducts are provided to direct cooling gas onto the outer and interior surfaces of a rotating article of glassware that is heated to a uniform temperature above the strain point of the particular glass composition from which the glassware is formed in order to temper the glassware by producing beneficial residual compressive stresses on the surfaces. The ducts have gas emitting nozzles that shape the cooling gas streams to conform to the shape of the glassware surfaces. The ducts and nozzles are so positioned that the cooling gas impinges upon the glassware surfaces tangentially and in a direction opposite to the direction of rotation of the surfaces to increase the effective velocity of the gas and to promote laminar flow of the cooling gas over the surfaces and thereby enhance cooling.

Abstract: A vacuum press construction having holes on the press face corresponding to aperture in the glass sheet to be shaped. The holes are sealed in a manner so as to minimize the amount of heat drawn from the periphery of the glass sheet apertures during the pressing operation and maintain glass edge strength at the aperture.

Abstract: In toughening a glass sheet, e.g. for use as an automobile window, by heating it to a temperature above the strain point and quenching the heated glass sheet by blowing a cooling medium such as compressed air against both sides of the glass sheet from two opposite sets of nozzles, the cooling medium is caused to impinge on each side of the glass sheet in such a pattern that the glass sheet is more efficiently quenched and consequently more highly toughened in a generally circular central region and a plurality of generally annular regions, which are substantially concentrical about the center of the glass sheet and radially spaced from one another, than in the remaining regions. This is effective in preventing the presence of impermissibly elongated particles when the glass sheet is fractured and also in lessening the difference between the maximum and minimum numbers of particles in unit areas of the fractured glass sheet.

Abstract: The invention relates to a glass lathe for producing preforms which may be drawn into energy transmitting fibers. The apparatus includes a head stock and a tail stock for rotatably holding a starter tube and the preform as it is built from the starter tube. The tail stock is movable along the lathe bed with respect to the head stock so that a preform may be drawn down to approximately the diameter of the starter tube. A carriage is provided on the lathe bed which carries at least one burner for melting a particulate quartz feed and depositing it onto the rotating surface of the starter tube. A slide member mounted on the carriage supports a container for catching particulate quartz which does not adhere to the tube and a coolant reservoir adapted to produce a fountain for contacting and cooling the tube downstream of the burner.

Abstract: The invention relates to a method of differentiated rate of hardening of a glass sheet by blowing a cooling gas in the direction of this sheet having two zones from nozzles. According to the invention, a simultaneous solidification of the glass sheet is produced at both zones of the sheet in spite of the differentiated treatments applied to establish a difference of hardening between the different zones of the sheet. Application is to the production of flat glass sheets.

Abstract: Apparatus capable of tempering bent glass sheets of different sizes and shapes including sharp bends about axes oblique to the length and width of the glass sheets is made possible by supporting end nozzle boxes of tempering apparatus in such a manner that they can be moved relative to center nozzle boxes and also permitting limited pivotal adjustment of the end nozzle boxes about both essentially horizontal and essentially vertical axes to permit the end nozzle boxes to move into positions conforming to the shape of corresponding end portions bent to different orientations relative to the length and/or width of the central portion of the bent glass sheets having different glass sheet patterns, including flat patterns.

Abstract: Nozzles are arranged in different densities transverse to a path of travel for glass sheets moving through a pass-through quench to facilitate removal of spent tempering medium to both lateral sides of said path of travel.

Abstract: Heat strengthened glass is treated to have a break pattern that permits the fractured glass sheet to be retained within an installation frame by moving a glass sheet through a heating area, force cooling the side portions of the moving sheet while cooling the intermediate portions of the sheet at a lesser rate to establish a temperature gradient between the side portions and the intermediate portion, and subsequently applying quenching medium to the entire moving sheet. The temperature gradient in the sheet is achieved by a plurality of baffles, e.g. plates having an imperforate center portion and apertured or slotted end portions and facilities movable relative to quenching nozzles to control passage of quenching medium through the slotted end portions of the baffles to control the temperature gradient imparted to the glass sheet. The movable facilities also permit tempering of glass sheets of varying transverse dimensions.

Abstract: The present invention is directed to an apparatus and process for the ion change hardening of glassware by passing the glassware through a stream of molten salt. The glassware may be arranged at different levels on a conveying means, provided with perforations to allow the molten salt to fall from level to level from an overhead salt distributor. The glassware may be positioned on a horizontally spinning rack so that molten salt continuously fills up and empties from the glassware. The molten salt is recycled from the bottom of the apparatus and may be replenished by adding salt to the recycle stream.

Abstract: In tempering a glass sheet, particularly a glass sheet having at least one major dimension more than 0.5 meter, by quenching said sheet with cold tempering medium while at a tempering temperature, prior art tempering apparatus developed insufficient temper particularly in the central portion of the glass sheet, as evidenced by fragments from the central portion exceeding code requirements for maximum size on destruction testing. The present invention provides a novel construction and arrangement of the tempering medium supply system that provides relatively wide escape paths in the direction of the glass sheet thickness for blasts of tempering medium applied toward the central portion of the glass sheet compared to the escape paths provided in said direction for blasts of tempering medium applied to the portion of the glass sheet beyond the central portion.

Abstract: While a heated glass sheet moves through a quenching section, the glass sheet is blown with air in the same portions so as to be quenched always in the same portions to provide on the glass surface rapidly cooled portions and uncooled portions. Thereby the residual strains on the glass surface are made different to prevent the generation of pieces or splines when the glass sheet is broken.

Abstract: A method of prestressing at least one of the glass sheets of a sandwich safety glass, while being bent in a furnace, the glass sheet, after passing through a bending zone, being passed by a blow system and cooled by cooling air in the furnace in a temperature zone above the transformation point but below the deformation point of the glass, and an apparatus for such prestressing comprising a travelling die supporting superimposed sheets, a bending furnace zone to soften the sheets, and a cooling zone, the cooling zone having a blow system that subjects the bent sheet or sheets to cooling air.

Abstract: Reducing kink in the leading edge portion of tempered flat glass sheets by applying a downward flow of air across the entire width of the leading edge portion of the upper surface only of the glass sheet as the sheet passes the boundary region between the exit of a furnace or heating area and the entrance into a cooling area where both upper and lower surfaces of the sheet are cooled throughout their entire extent to impart at least a partial temper to the sheet.

Abstract: Producing glass sheets having improved break patterns over those produced either by typical heat strengthening procedures or by heating to a tempering temperature followed by natural cooling.

Abstract: A glass sheet is thermally treated, for example thermally toughened, by heating the glass sheet, and lowering the sheet into a gas-fluidized bed of particulate material which is at a glass-treatment temperature, for example quenching temperature. Extraction of gas from a localized upper region of the bed is commenced prior to the lowering of the hot glass sheet into the bed in order to produce gradually an unfluidized static packed condition of the material in that upper region of the bed. The glass sheet is lowered into the bed at a time after commencement of gas extraction which is such that the lower edge of the sheet passes through that upper region prior to full attainment of the static packed condition.

Abstract: Thermally toughened glass sheets of thickness 2.5 mm to 4.0 mm for use as motor vehicle side or rear windows, are produced by quenching producing an average central tensile stress in the range 62 MN/m.sup.2 to 44.0 MN/n.sup.2. At least one gas jet is directed at the glass sheet to augment toughening stresses and produce at least one strip-shaped region of more highly toughened glass. The central tensile stress in the strip-shaped region is in the range from 2 MN/m.sup.2 to 5 MN/m.sup.2 greater than the average central tensile stress in the glass sheet. There are major and minor principal stresses in the strip-shaped region acting in the plane of the glass sheet. The difference between the major and minor principal stresses is in the range 5 MN/m.sup.2 to 25 MN/m.sup.2.

Abstract: A method of thermally toughening a glass sheet in which the glass sheet is advanced through a quenching station and subjected to a localized gas flow. The localized gas flow is pulsed at a repetition frequency related to the speed of advance of the glass through the quenching station. The toughened glass sheet so produced has a distribution of regions of more highly toughened glass interspersed with regions of lesser toughened glass.

Abstract: The invention contemplates a circular spectacle-lens blank which is optically finished on both its front and back surfaces and which is characterized by locally hardened registering central areas of both surfaces. The hardened areas are sized to be universally included within the spectacle-frame profile of all frames within a given variety of frames, and the outer annular areas are unhardened and of such effective radial extent as to embrace all of such profiles within said variety, so that each finished and hardened blank is adapted for later edging to the profile of a later selected one of the frames within the given variety. Various methods are described for creating the indicated locally hardened regions on the otherwise-finished lens blanks.

Abstract: A process for the production of a gradient photochromic glass article comprising the selective over-nucleation of a limited portion of the article followed by a photochromic development heat treatment of the entire article, and the product of this process, are described.

Abstract: Glass lenses or lens blanks, containing all the ingredients necessary to produce phototropic or photochromic behavior, are treated in a conventional production furnace to produce a locally variable heat treatment, wherein at least one portion thereof is raised to a temperature exceeding the glass strain point but not the softening point, and other portions are heated to variable temperatures decreasing from the strain point. The treatment causes development of phototropic or photochromic behavior only in those portions of the lenses or lens blanks exposed to the temperature above the strain point.

Abstract: Glass lenses or lens blanks, containing all the ingredients necessary to produce phototropic or photochromic behavior, are treated in a conventional production furnace to produce a locally variable heat treatment, wherein at least one portion thereof is raised to a temperature exceeding the glass strain point but not the softening point, and other portions are heated to variable temperatures decreasing from the strain point. The treatment causes development of phototropic or photochromic behavior only in those portions of the lenses or lens blanks exposed to the temperature above the strain point.

Abstract: A method of treating ophthalmic quality lenses or lens blanks that produces a reversible progressive local variation in phototropic behavior with a continuous variation in transmissivity. The lens or lens blank is composed of a potentially phototropic glass containing all the necessary ingredients including uniformly dispersed silver halide particles therein to develop a phototropic behavior during the heat treatment of the present method. The steps of the present method include mounting the lens or lens blank in carrier means, heating the lens or lens blank thus mounted in a heat treatment furnace at a temperature sufficient to develop the phototropic behavior of the potentially phototropic glass. Characteristically the required heat treatment temperature to develop this phototropic behavior is one which exceeds the strain point of the glass but not the softening point thereof.

Abstract: Thermally toughened glass sheets of thickness 2.5 mm to 3.5 mm, for use as motor vehicle side or rear windows, are produced by differential quenching producing a distribution of regions of more highly toughened glass interspersed with regions of lesser toughened glass. The average central tensile stress is in the range 62 MN/m.sup.2 to 53 MN/m.sup.2, and there is a distribution of areas in which the principal stresses acting in the plane of the glass sheet are unequal. The principal stress difference in some of the areas is at a maximum in the range 8 MN/m.sup.2 to 25 MN/m.sup.2, the major principal stresses in adjacent areas in which the principal stress difference is a maximum are in different directions, and the distance between the centers of such adjacent areas is in the range 15 mm to 30 mm.

Abstract: The invention achieves local variation, or a continuous gradation, in photochromic or phototropic properties across the face of glass lenses and lens blanks, especially those of ophthalmic quality. The lenses and lens blanks contain all those ingredients required to produce photochromic or phototropic behavior. They are exposed to a locally variable temperature field or environment, in such manner as to, in at least one portion of the lens or lens blank cause the temperature therein to exceed the strain point but not the softening point of the glass. In other portions of the lens or lens blank the temperature is below the strain point, thus causing development of phototropic or photochromic behavior only in those portions of the lens or lens blank exposed to the temperatures above the strain point.

Abstract: A laminated glass windshield is manufactured by bonding glass plates having a thickness of 1.5 to 2.5 mm together wherein the peripheral portions of the outer surfaces of the glass plates are subjected to a plane compressive stress of 200 to 500 Kg/cm.sup.2.

Abstract: Thermally crystallizable glasses of the Na.sub.2 O--Ta.sub.2 O.sub.5 --SiO.sub.2 and the Na.sub.2 O--Li.sub.2 O--Ta.sub.2 O.sub.5 --SiO.sub.2 systems, and glass-ceramics made therefrom which are highly transparent, have high indices of refraction, and excellent strength properties. By varying the heat treatment schedule for crystallization of a glass to a glass-ceramic, a specific high index of refraction coming within a prescribed range may be imparted to the finished, transparent glass-ceramic. A transparent glass-ceramic having two or more different indices of refraction may also be produced.

Abstract: The invention achieves local variation, or a continuous gradation, in photochromic or phototropic properties across the face of glass lenses and lens blanks, especially those of ophthalmic quality. The lenses and lens blanks contain all those ingredients required to produce photochromic or phototropic behavior. They are exposed to a locally variable temperature field or environment, in such manner as to, in at least one portion of the lens or lens blank cause the temperature therein to exceed the strain point but not the softening point of the glass. In other portions of the lens or lens blank the temperature is below the strain point, thus causing development of phototropic or photochromic behavior only in those portions of the lens or lens blank exposed to the temperatures above the strain point.

Abstract: Method for reducing the likelihood of cathode ray tube glass bulb and bulb component fracture which are caused by temperature cycling in the cathode ray tube manufacturing process and which are associated with defects in the glass. Temperature gradients between glass exterior surfaces and glass interior, arising during cooling, are locally reduced. In a preferred embodiment, a thermal insulator is applied prior to or during cooling, over a defect and its vicinity in order to locally reduce the rate of surface cooling and thus locally reduce the cooling-induced surface tensile forces. An improved component-in-process is depicted which has a reduced susceptibility to thermally induced fracture.