Patent GB-821927-A (GB)
Title: Method and apparatus for bending glass sheets
IPC: C03B23/025
Filed: 1956-08-07
Abstract: 821,927. Bending glass sheets. LIBBEYOWENS-FORD GLASS CO. Aug. 7, 1956 [Aug. 11, 1955], No. 24121/56. Class 56. To bend a glass sheet, particularly for the tops of cars and requiring three sharply bent edges on a substantially rectangular sheet, the sheet is supported along the undersurface of substantially the whole of one marginal edge area as well as a further area to balance the same, heated until the edge area softens and then a portion intermediate opposite ends is simultaneously supported and bent by engaging and lifting the portion first with a substantially flat support and then with a curved support while simultaneously continuing to support the bent portion and other portions of the marginal edge. The bending mould 12 is supported on a rack 11 comprising parallel side and end rails 13, 14, uprights 15 and guide rails 16 to engage flanges on the rolls of a conveyer used in the furnace. The mould 12 comprises end sections 18 hinged to a centre section 17, the section 17 comprising side bars 19, 20 supporting shaping rails 21, 22 with shallow concave shaping surfaces 24, the bar 19 and rail 21 being also curved inwardly at each end. Each section 18 comprises a side bar 25 aligned with and pivoted to bar 20 and end bar 26 joined to bar 25 and curved at its other end to meet bar 19, the bars 26, 19 being pivoted together by means of outwardly extending parts 33, 35. The shaping rail 28 carried by section 18 comprises a part 30 aligned with rail 22 and a part 31 joined thereto and gradually and then steeply curved to meet rail 21. The mould sections 18 are supported on uprights 15 for movement from an open, Fig. 6, to a closed position, Figs. 2, 3, by a transverse rod 36 secured to the under surface of rails 28 and side bars 25, the ends of the rod being joined by links 37 and pins 38 on the uprights. A glass sheet 40 is supported on the outer edge e of the surface 29 of rails 28, the edge e giving flat linear support in the open position. The sheet 40 is further supported in this position by blocks 39, inwardly of the rails 21 22, carried at each end of rods 41 movable vertically downwards as the rails 28 are moved upwards to closed position. Each rod 41 is steadied by a rod 48 passing through a ring .47 on the rail 21 or 22 and has a slot 42 under each block 39 in which slides one end of a lever 43 pivoted at 44 to a plate 45 on rail 21 or 22 and with its other end freely bearing on the underside of support rod 36 and guided between angle plates 46. As the sheet softens and sags, the end sections 18 rotate about the links 37 so that their outer edges rise and inner ends move downwardly carrying the centre section 17 therewith. At the same time, pressure on the levers 43 is reduced and they pivot to lower the blocks 39 to below the level of surfaces 24, the glass sheet then resting solely on the arcuate shaping surfaces 24, 29. Heat shields 49, 50 above the mould removably supported on rods 51 carried by struts 52 and a lower shield 56 on rails 16 shade from radiant heat all but the three areas f, g, f adjacent the edges of the glass sheet 40 where greatest curvature is required. The shields are of material of higher specific heat than glass and they also act to withdraw heat from the glass in the shaded areas. Specifications 727,200 and 745,992 are referred to.