Patent GB-518652-A (GB)
Title: Improved method and apparatus for forming sealed hollow articles of glass
IPC: C03B23/24
Filed: 1938-09-01
Abstract: 518,652. Making hollow glass blocks. CORNING GLASS WORKS. Sept. 1, 1938, Nos. 25622, 25623, and 25624. Convention dates, Sept. 8, 1937, Sept. 16, 1937 and Oct. 12, 1937. [Class 56] Relates to a method of forming. sealed hollow glass articles, such as building blocks, in which pairs of complemental preformed parts are heated along their edges and are then pressed together to weld the softened edges. According to the invention, the character of the atmosphere in a finished article is controlled by allowing entrapped gas to become hot and escape from between the complemental parts after the edges have been heated and before joining them together, the operation being conducted at normal atmospheric pressure. The method may be carried out by means of hand tools, but a suitable apparatus for the purpose comprises a table 11, Fig. 1, having a vertical stud 12 on which a heater 13 is pivoted so that it can be swung from one to another of two holding-devices 14 secured to the table. A second holder 16 is supported above each of the holders 14, and it can be raised and lowered by means of a handwheel 26. The holder may be provided with a mechanical chuck for gripping a section G<1> of a glass block, but is shown as comprising a suction-cup 18 connected by a passage 27 in its stem 19 with any suitable source of suction. The heater consists of a chamber 30 provided with burner openings 31 in alignment with the edges of the glass parts G, G' and supplied with a combustible gas mixture by a conduit 29. In operation, the glass parts G, G' are placed in the holders 14, 16 respectively, and when the edges of the parts have been softened, the burner 13 is swung to the other holding-devices while the wheel 26 is turned to bring the parts G, G' close to one another. The glass parts are retained in this position for a predetermined time to allow the air between the parts to become hot and escape, and then the part G<1> is again lowered and pressed against the part.G. Instead of being kept stationary, the part G<1> may be moved slowly towards the end of its movement. The glass parts may have notches formed in their edges, as shown in Fig. 7, to allow the air to escape, the notches being eliminated when the parts are pressed together. The sealed edges may be cooled immediately by a moulding device 34, Figs. 1 and 3, composed of two parts pivoted together, which are opened and closed by a fluid-pressure cylinder 36. The mould 34, which may be cooled by circulating fluid through an interior cavity is pressed against the glass article along the zone of sealing and ensures a flat outer surface on the glass. The mould may also be shaped to form a recess or groove in the glass along the line of sealing, to provide a space for a reinforcing rod or the cement used for joining the blocks. In a modified form of moulding apparatus, the glass is pressed by members which are pivoted to the holders 14. Powdered or granular material, such as glass or porcelain may be applied to, the soft surface of the glass to provide a better bond between the block and other material such as cement. The powdered material may be attached to the vertical surface of the mould 34 by an adhesive which will burn in contact with the hot glass. In another form of apparatus, shown in Fig. 9, the part G, G' are held in suction holders 54, and the. parts G' are raised into contact with the parts G by means of pneumatic cylinders 56. Each of the upper holders 54 is surrounded by a shield 62, and the lower holders are surrounded by shields 63 which are raised into contact with the shield 62, by pneumatic cylinders 64, to form an enclosed chamber. The shield 63 is formed with openings near the upper edge through which air. is blown on to the sealed edges of the glass to cool them, an aperture 67 being provided to allow the air to'escape. The shields 62, 63 form a chamber enclosing the glass parts which enables the temperature, density, and amount of gas trapped between the glass parts in the sealing operation to be controlled; the shield being filled, for example, prior to sealing, with gas at the effective temperature of the glass parts.