Patent GB-933416-A (GB)
IPC: C03B23/24
Abstract: 933,416. Glazing units. LIBBEY-OWENS-FORD GLASS CO. July 29, 1961, No. 27590/61. Class 56. A method of producing all-glass multiple sheet glazing units, comprises preheating a pair of glass sheets, moving the preheated sheets forwardly through a sealing station, heating the marginal edge portions at one side of the sheet to a pliable condition and pressing the edges into sealing contact to form an edge-wall between the sheets, moving the sheets rearwardly beyond the sealing station and rotating to bring the marginal edges of a second side of the sheet into the sealing position, moving the sheets forwardly through the sealing zone to seal said second edge repeating the rearward movement and rotation until all the edges have been sealed together and then passing the glazing unit through an annealing zone, the whole operation being automatically controlled. The apparatus, Fig. 3, comprises a preheating section B formed by tunnels E and F, and a loading area L. The inner ends of the tunnel communicate with transfer area G of the sealing section C. The annealing section D comprises tunnels H and J and unloading area U the tunnels communicating with transfer area K of sealing section C. Operation.-The glass sheets are loaded on to racks at position L and pass through the preheat tunnel E. At position G the sheets are transferred to carrier O, which is heat conditioned in chamber M and moves along track T to the transfer position. Meanwhile, the racks are returned to the loading position L through tunnel F. The glass sheets are supported by carrier O through the sealing zone C and after sealing are transferred to racks at area K, then they pass through annealing tunnel J at zone D to unloading area U, the racks being returned to area K through tunnel H. Loading.-Rack 48 located at L on platform 62 (Fig. 4), is loaded with a pair of glass sheets 31 and 32 which are clamped in position. The doors 45 at the entrance of tunnel E are opened and pneumatic cylinder 75 actuated to raise bar 72 to lift the rack above above the rails 63. Cylinder 70 propels conveyer 66 horizontally into tunnel E. The cylinder 75 is reversed to lower bar 72, thus depositing the loaded rack 48 again on platform 62. Conveyer 66 is returned to receive another rack and the doors 45 are closed. Each rack entering preheating tunnel E, by progressive lifting of the racks from fixed rails by means of the associated walking beam conveyer 49, Fig. 9, eventually arrives at the transfer area G. Transfer of sheets from rack to carrier.-The loaded racks arriving at G are carried forwardly and deposited on rails 83 of platform 84 (Fig. 9). A cylinder 117 is axially located in a vertical plane coincident with the medial line of rack 48 and the aligned axes of the platens 106 and 107. An elevator bracket 119 actuated by piston-rod 118 of cylinder 117 passes upwardly between rails 83, engaging the rack 48 which is carried upwards until the sheets are engaged between the vacuum platens 106 and 107 of carrier O, which carries the glass sheets to the sealing area C. The carrier may be halted at Y, Fig. 3, where any unsuitable glass may be discarded into a cullet cast by releasing the vacuum of the gripping platens. Sealing.-The movable platen 106 is retracted to establish an air-space between the sheets of glass, the sheets then being moved forward through an arrangement of burners 135 (Fig. 11), including fusion burners 136 comprising a pair of manifolds mounted on a baseplate 138 and equipped with angularly disposed nozzles 139. After the edge portion of the sheets have passed the flames and have been heated to a temperature of 1800-2000 ‹ F. they pass through shaping rollers 140 which press the fused edges into sealing contact. The sealed wall is passed through a second burner area 141 to achieve a fire finish. A feeder device 144 situated ahead of the rollers is adapted to insert a small metal tube between the edge of the glass sheet located adjacent a corner of the sheet to provide an opening for dehydration of the glazing unit. The carrier O moves rearwardly over and beyond the sealing station the sheet is disengaged from platen 107 and the shaft 103 fixed to platen 106 is rotated to bring another side of the glass sheet into a position to be sealed, suction being re-applied through platen 107. The carrier is moved forward again through the burner area to seal the second edges of the glazing unit. This process is repeated until all the edges are sealed. The burner arrangement is adapted to be raised or lowered by means of cylinders 152 and 157 (Fig. 10, not shown), into a suitable position for contacting the edges of the glass unit. Annealing.-After sealing is completed the carrier is moved forwardly to transfer area K, where the sealed sheets are transferred to racks 174 (similar in construction to rack 48) by means of which the sheets are carried progressively through the tunnel H of annealing section D on a walking beam conveyer. The procedure in this section is similar but reverse of the procedure in the preheating section. The annealed glazing units are unloaded at U. The process described is carried out automatically by associated complex electrical circuits. Alternative embodiments of the apparatus are also indicated in Figs. 21-22 (not shown). Fig. 22 employs similarly located preheating and annealing tunnels and provides for the production of two units simultaneously in substantially overlapping cycles of operation. In Fig. 21 the annealing section D is dispensed with and the " return tunnel " of the preheating section employed as the annealing tunnel.