Patent GB-425996-A (GB)
Title: Improved process and apparatus for annealing glass plates
IPC: C03B35/16
Filed: 1933-09-26
Abstract: 425,996. Annealing glass plates. PILKINGTON BROS., Ltd., 703, Tower Building, Water Street, Liverpool, and SLOCOMBE, F. E., Sandall Grove, Kirk Sandall, Doncaster, Yorkshire. Sept. 26, 1933, No. 26457. [Class 51 (ii)] Apparatus for annealing glass plates comprises a heat-insulated chamber 31 adapted, on removal of the cover 32, to receive a single plate and provided with means for maintaining a uniform temperature around the plate, the latter being supported on an endless series of rollers 1 which are maintained in both rotating and travelling motion so that the plate rests substantially stationary on them. The rollers 1 are carried by side chains 2 passing over sprockets 3, 4, and are provided on their outer ends with pinions 21 which have a pitch diameter equal to the diameter of the rollers and engage, along the upper horizontal flight, with fixed racks 22. The chains 2 are driven through gearing 14, 15, 16, from a shaft 17, and as they travel along the upper flight the rollers 1 are rotated so that they roll under the plate 67, Fig. 3, without imparting any movement thereto. To limit any movement of the plate which may be produced by inaccuracies in the mechanism, stops 68 are provided at each end of the upper flight. The casing 31 and cover 32 are formed of a metal sheathing 34 with a lining 35 of heat-insulating material, and each of the apertures through which the end of a roller 1 projects is sealed by a pair of discs 50, Fig. 3, mounted on the roller and interleaved with discs 51 of adjacent rollers. The discs 50, 51 are accommodated in a space 47 formed by cutting away a portion of the lining 35, this space being enclosed on the inner side by metal strips 48. The means for equalizing the temperature around the plate 67 comprises upper and lower boxes 52, 53, through which the atmosphere of the casing is circulated, these boxes being provided internally with fins 54 which are deeper at the centres of the boxes than at the ends and deeper or closer together at the centres than at the edge portions. The entire casing is carried by a girder structure 7, 8, 24, 25 mounted on wheels 11 and supporting a fan 55 and its driving motor 56 ; pipe connections 57 ... 62 are provided for the circulation of the casing atmosphere through the boxes 52, 53. Unions 64, 65 permit removal and replacement of the cover 32 and, to maintain a slight pressure within the casing to prevent entry of air, a small amount of air, preferably preheated, is admitted by the pipe 66 to the suction side of the fan 55. Electric heating elements 69, arranged to radiate on to the end portions of the rollers 1, are provided for regulating the rate of cooling and for bringing the apparatus up to the desired working temperature. The wheels 11 run on a track 12 on a trolley 13 which, as shown in Fig. 5, travels on rails 71 between the plate-receiving position 31<a> and the position 31b. When in the latter position, the cover 32 is replaced, the unions 64, 65 connected, and the fan 55 started, whereupon the annealing chamber 31 is run off the rails 12 on to the track system 72 and the trolley 13 returned to position 13b. The track system 72 includes turntables at 73, and by the provision of a plurality of chambers 31, indicated at 31<c> ... 31<g>, the annealing of a number of plates can be carried on simultaneously. When a plate in a chamber has been completely annealed, the latter is brought to position 31h and the plate discharged on to a conveyer 75, whereupon the empty chamber, reheated during its travel through positions 31<i>, 31<k>, is returned to the trolley 13 at 13b. A modification is described in which the rollers 1 are rotated by a motor-driven endless chain engaging the pinions 21 ; this chain is normally driven at such a speed that the plate remains substantially stationary but this speed may be increased to discharge the plate on to the conveyer 75. In this construction, the stops 68 may be arranged to actuate switches in the circuit of the motor operating the driving chain so as to impart to the plate a slow backward and forward movement on the rollers 1.