GB1043903A - Apparatus for the flat contact tempering of glass - Google Patents

Abstract

An apparatus for tempering a glass sheet by contact when laid flat between a lower plate 2 (Fig. 1, not shown) and an upper plate 3 includes means for forcing a gas under pressure (e.g. air) through passageways 5 in the lower plate 2 to create a cushion of gas beneath the glass sheet 11 during the transfer of the latter on to the lower plate and before the upper plate 3 is lowered into contact with the sheet. The lower plate 2 consists of a trued aluminium table having hollow passageways 4 for the circulation of a cooling fluid, and the passageways 5 are connected to a duct B for the passage of low pressure air, which may be heated. The surface of plate 2 is also divided into zones by slots and grooves to permit of expansion. Air is passed through the passageways 5, and is so directed as to assist in the movement of the sheet, during transfer of the sheet 11 on to the plate so that the sheet is not harmed by contact with the plate, after which the pressure is released until after the tempering operation. The upper plate 3, movable by a ram 10 towards plate 2, is made up of separate but contiguous components 3a forming a contact surface which is substantially plane but can deform to conform to the contour of the upper surface of the sheet 11. The individual components 3a comprise a base 13 (Fig. 2, not shown) attached to a component 14 which is suspended from main frame 12 by a collar 18 resting on a flange of component 15 attached to frame 12, the parts 13, 14 thus being adapted to move vertically relative to part 15. A flexible membrane 20 keeps the parts 13, 14 separated and also serves as a passage for a cooling fluid which passes against the bottom face of base 13 and out through a constricted passage 23. Varying the pressure of tne fluid alters the pressure of the plate 3 on sheet 11. Both plates may be covered with a removable fibre-glass fabric 8 attached to a frame 9, and there may be a low coefficient of expansion metal between the fabric and the plates.