Patent GB-1044039-A (GB)
Title: Method and apparatus for surfacing glass
Inventor: HANDS HORACE GEOFFREY
IPC: B24B7/24
Filed: 1963-10-14
Abstract: 1,044,039. Grinding and polishing glass. LIBBEY-OWENS-FORD GLASS CO. Oct. 14, 1963, No. 40411/63. Heading B3D. A method of simultaneously surfacing both sides of a glass sheet 40, Fig. 1, moving along a predetermined path comprises passing the sheet through the space defined by a plurality of pairs of opposed, generally rectangular, surfacing members 44, 58 which are driven by eccentric means 45, 60 effective to impart a curvilinear translation to each member such that the longitudinal edges thereof remain substantially normal to the path of movement of the glass, and driving all the surfacing members in the same direction and synchronizing the motion of opposed surfacing members of each pair such that they are 180 degrees out of phase with respect to one another and also such that the upper surfacing member of one pair is in phase with the lower surfacing member of the pair or pairs immediately adjacent thereto. In the apparatus for carrying out the method and shown schematically in Fig. 1, each surfacing member is of rectangular shape, the lower members 58 being carried by eccentrics 60 on shafts connected by worm gearing 154, 165 to double-ended motors 46, and the upper members being carried by eccentrics 45 on shafts connected by worm gearing 73, 77 to doubleended motors 46. The motors are controlled by selsyn devices 61 so that the desired phase relationship between the surfacing members is maintained during the surfacing operation. The upper platens are raised and lowered by telescoping part of the drive to the eccentrics effected by a motor 49, shafts 112 and gearing 111 to within a short distance above the glass, final lowering being effected by manuallyoperated handles 51. Pneumatic apparatus is connected to cylinders 56 to initially balance the weight of the platens and then to apply a controlled pressure acting to press the platens against the glass at a constant pressure of between 0 and 4 p.s.i. In the event of breakage of the glass occurring, a switch is actuated to operate the pneumatic apparatus and raise the upper platen which is prevented from engaging the lower platen by a mechanical stop. The telescopic drives for each upper platen are mounted in cross-members 65, Fig. 9, each drive having a housing 70 secured to the member and slidably receiving a sleeve 87 in which is mounted bearings for a shaft 85. The lower end of the shaft carries the eccentric 45 and the upper end of the shaft is keyed to a member 83 secured to a worm-wheel 73 engaged by a worm 77 driven from the motor 46 whereby the platen is moved with a circular translational movement of between 75 and 600 r.p.m. A cylindrical member 93, Fig. 10, is secured to the sleeve 87 and receives a lift block 97 which extends through a vertical slot 99 in the housing and is disposed between lugs 106 on a liftblock 104 engaged by a screw 105 connected by bevel gearing 110, 111 and a shaft 112 to a two-speed reversible double-ended motor 49 which is effective to lower the platen at a slow speed and raise it at a high speed. One end of one of the shafts 112 is extended to receive the handle 51 for manual adjustment of the platen. The lift block 97 is received with clearance 107 between the lugs 106 of lift block 104 and normally the weight of the platen causes the blocks 97 to rest on the lower lugs of blocks 104. However, the weight of the platen is lifted so that the lift blocks 97 bear against the upper lugs 106 by pneumatic pressure supplied to the upper end of cylinders 56, Fig. 16, to cause toothed segments 123 engaging racks 118 secured to the sleeves 17 to urge the sleeves upwardly. With the platen then lowered, by manual operation of the handle 51, into contact with the glass sheet, pneumatic pressure can be supplied to the other ends of the cylinders 56 to urge the lift blocks from the upper lugs 106 and apply a controlled pressure to the platens. The amount of clearance 107 is adjustable to be less than that of the thickness of the glass so that the blocks 97, 104 act as mechanical stops to prevent the platens contacting each other in the event of breakage of the glass, the clearance being indicated by gearing interconnecting the blocks and connected by gearing 137, 141, square shafts 143, Fig. 11, gears 147 and shafts 150, 151 to respective pointers 148, 149. The clearance is periodically adjusted to compensate for wear of the platen. Limit switches 184, 185, Fig. 10, control the motors 49 so as to limit the upper and lower positions of the upper platens. The lower platens 58 are mounted on eccentries 60, Fig. 17, on the upper end of shafts 156 keyed to worm-wheels 154 engaged by worms 165, Fig. 1, connected to the motors 62 for imparting a circular translational movement to the lower platens. Each shaft 185 is rotatably supported in bearings in a housing 152 secured to a cross-member of the apparatus, and the lower end of the shaft is rotatably supported in bearings in a sleeve 161 slidable in a casing 162 secured to the housing. Vertical movement of the sleeves to effect vertical adjustment of the platen is effected by worm-wheels 171 which are driven by worms on shafts 177, Fig. 8, connected by couplings 180 to a motor 63 and engage threaded shafts 172, Fig. 17, connected to yokes 173 abutting the shafts 156 and prevented from rotating by keys 174 engaging ways 175. The lower ends of the shafts 172 have extensions 181 formed with abutments 182 co-operating with switches 188, 189 to limit the upper and lower positions of the lower platen. The eccentrics 45 and 60 are identical and each consists of two plates 190, 191, Figs. 20 and 21, which are adjustable relative to each other to vary the throw of the eccentric along a guideway 193 by a screw 198. The plate 190 has a shaft 192 for receiving the platen, and the plate 191 is integral with the shaft 85 or 156 of the upper or lower platen drive. The plates can be secured in their adjusted positions by screws 194 and weights 203 can be secured to the eccentric to compensate the out-of-balance of the eccentric. The plate 190 is also formed with a split clamp 201 having three pointed screws 202 for engagement with a groove 208, Fig. 27, in a mounting 207 on the platen. Each platen consists of two parts 205, 206, Fig. 26, separated by a gap 210, each part having a base-plate 209 on which is a mounting 207 for connection to an eccentric. Frames 211 are carried by each plate 209 and overlie the other plate so as to slide in guideways 213 in that plate, the arrangement permitting relative longitudinal movement between the parts while maintaining the distance between the eccentrics constant to permit such movement as may be caused by the effect of temperature changes during the surfacing operation. A second plate 220, Fig. 27, is removably secured to each base-plate 209 by clamps 221. The plates 220 are bevelled on their exposed surfaces and covered by polishing pads 223. A polishing age it, such as rouge, is applied to the upper and lower surfaces of the glass by applicators 224, 225, Fig. 7, and apparatus 226, 227 is provided to wash the glass as it is fed between the surfacing members by pinch rolls 67. The apparatus may be used for grinding both sides of glass sheet.