Patent GB-1395717-A (GB)
Title: Production of toughened glass sheets
IPC: C03B23/031
Filed: 1971-09-13
Abstract: 1395717 Tempering glass sheets TRIPLEX SAFETY GLASS CO Ltd J E POWELL and P H RICHARDS 5 Sept 1972 [13 Sept 1971] 42561/71 Heading C1M Glass sheets are toughened by heating a glass sheet while it is being advanced along a horizontal path, advancing the sheet on to a horizontal support surface, holding the hot sheet in contact with the support surface, rotating the support surface to a vertical disposition with the glass sheet maintained in contact therewith, releasing the sheet from the support surface, and lowering the sheet at a controlled rate into a chilling liquid. Preferably the support surface is one of two bending dies, the dies being closed prior to the rotation of the die to bend the sheets. In one embodiment (Fig. 2) the support surface is provided by a lower bending die 24 which is one of four dies mounted on the faces of a rotatable member 16. In use a glass sheet is advanced on to the die 24 on rollers 73 disposed in slots in the die until it contacts stops 26 and thereby activating a switch 75 to retract the rollers 73 into the die. At the same time an upper die 38 descends to bend the sheet. After a fixed time a limit switch LS 1 activates a cylinder 98 to retract the upper die 38, after which another switch LS2 causes a shaft 17 and therefore the member 16 to rotate through 90 degrees so that the surface of the die 24 is vertical. As the member 16 reaches the 30 degree position a port is exposed at the centre of the member 16 so that suction may be applied to the die 24 to maintain the bent sheet in contact with the die surface, a plurality of holes being provided in the die surface for this purpose. As the member 16 is being rotated support blocks 34 are raised up from a bath of chilling liquid maintained in a tank 27 below the member. The blocks 34 are heated by means 96 to obviate thermal shock. At the same time switch LS5 causes retraction of the stops and the replacement of the suction by a hot air blast thus causing separation of the sheet from the die surface. The sheet is then lowered on the support blocks into the chilling liquid. The glass is then moved out of the tank 27 on support rods 31 carried on an inclined conveyer 29.  In a second embodiment (Fig. 6) a pair of upper and lower bending dies 45, 46 which rotate as a unit is employed. The glass sheet is fed on to rollers 47 between the dies 45, 46 after which the rollers 47 are retracted and the dies closed. At the same time a hoist 59 is activated which draws back a bar 57 into forks 58 thereby causing the scissors linkage 55, to make tong bars 51, 52 grip the sheet. With the dies 45, 46 closed and the tong bars 51, 52 still gripping the sheet the entire unit is rotated through 90 degrees by means of two arcuate segments 101 which such having teeth 102 engaged by a gear-wheel 103. The two dies 45, 46 are then moved apart and the sheet which is still gripped by the tongs 51, 52 is lowered towards a tank 27 of chilling liquid 28. At this time the lower edge of the sheet comes into contact with a cradle 117. The grip of the tong bars may then be released enabling the cradle's downward movement to complete the immersion in the chilling liquid 28. To temper flat glass sheets, flat dies may be substituted for the shown bending dies in either of the two embodiments referred to above.