CONVEYING SHEETS OF GLASS USING SHAPED ROLLERS

Abstract

A roller for conveying sheets of glass, includes at its surface a conveying zone for the sheets of glass, the roller including a straight axis of revolution, the conveying zone forming a curved surface of revolution about the axis of revolution, the roller being asymmetric on either side of its, minimum or maximum, extreme diameter. A plurality of the rollers can also serve to bend running sheets of glass.

Claims

1. A roller, which is a diabolo roller or a barrel roller configured to be part of a set of rollers forming a conveying bed for sheets of glass at a temperature greater than 400° C., comprising at its surface a conveying zone for the sheets of glass, said roller comprising a straight axis of revolution, the conveying zone forming a curved surface of revolution about said axis of revolution, said roller being asymmetric on either side of its extreme diameter, the extreme diameter corresponding to a minimum diameter for the diabolo roller or the extreme diameter corresponding to a maximum diameter for the barrel roller, a diameter of the roller varying uniformly on either side of its extreme diameter.

2. The roller as claimed in claim 1, wherein a ratio of axis lengths corresponding to two sides of the conveying zone on either side of the extreme diameter is in the range from 0.25 to 4.

3. A device for conveying sheets of glass running one after another, comprising at least one roller of claim 1, which is configured to turn about its axis.

4. The device as claimed in claim 3, further comprising a plurality of said rollers, which are substantially mutually parallel, forming a bed of rollers that is configured to come into contact with one and a same face of the sheets of glass.

5. The device as claimed in claim 3, wherein the roller is a first roller, and wherein the device comprises a second one of said roller, the first and second rollers forming a pair of rollers, wherein surfaces of revolution of the first and second rollers are complementary and exhibit a constant spacing along an entire length of the conveying zone.

6. The device as claimed in claim 5, wherein the axis of the first roller is at a lower level than the axis of the second roller, and wherein the extreme diameter of the first roller is a minimum value, the extreme diameter of the second roller being a maximum value.

7. The device as claimed in claim 5, further comprising a plurality of said pair of rollers forming a bed of lower rollers and a bed of upper rollers for applying a bend to the sheets of glass passing between the beds of lower and upper rollers, said bend having at least one transverse direction perpendicular to a conveying direction of the sheets of glass.

8. The device as claimed in claim 7, wherein the beds of upper and lower rollers have an upward or downward curved profile in the conveying direction of the sheets of glass in order to also apply a longitudinal bend to the sheets of glass.

9. The device as claimed in claim 7, further comprising air blowing nozzles for blowing air between rollers of a same bed in order to carry out heat strengthening of the glass.

10. A method for conveying sheets of glass, comprising conveying sheets of glass running one after another by the device of claim 3.

11. The method as claimed in claim 10, wherein a plurality of sheets of glass are conveyed side by side.

12. The method as claimed in claim 10, wherein the device comprises a plurality of pairs of rollers such that, for each pair of rollers, surfaces of revolution of the rollers of said pair are complementary and exhibit a constant spacing along an entire length of the conveying zone, corresponding to a thickness of the sheets of glass, said pairs of rollers forming a bed of lower rollers and a bed of upper rollers, the sheets of glass being bent at a deformation temperature on passing between the lower and upper beds of rollers, said bend having at least one transverse direction perpendicular to the conveying direction of the sheets of glass.

13. The method as claimed in claim 12, wherein the lower and upper beds of rollers have an upward or downward curved profile in a conveying direction of the sheets of glass, the sheets of glass also being bent in a longitudinal direction on passing between the lower and upper beds of rollers.

14. The method as claimed in claim 12, wherein a plurality of sheets of glass are bent simultaneously side by side.

15. The method as claimed in claim 14, wherein the sheets of glass form two groups situated on either side of the extreme diameter of the rollers, each sheet of a group having, corresponding to it, a sheet of the other group, the two sheets, upon bending, taking on symmetric shapes to one another with respect to a plane passing through the extreme diameter of the rollers.

16. The method as claimed in claim 12, wherein, after bending, air is blown onto the sheets of glass between rollers of one and the same bed in order to heat strengthen the glass.

17. The roller as claimed in claim 2, wherein the ratio is from 0.8 to 1.2.

18. The device as claimed in claim 9, wherein the air blowing nozzles blow air between rollers to carry out tempering of the glass.

19. The method as claimed in claim 11, wherein the plurality of sheets of glass is two or four or eight sheets of glass.

20. The method as claimed in claim 12, wherein the deformation temperature is between 400 and 700° C.

Description

[0028] FIG. 1 shows two rollers 1 and 2 according to the invention forming a pair of rollers for bending two sheets of glass 4 and 5 passing side by side in a conveying zone 3. The bottom roller 2 is of the “diabolo” type. This roller comprises a straight axis 6 and a surface of revolution 7. This surface of revolution comprises a circle, the center of which is on the axis and of minimum diameter comprising the point 8. The surface of revolution is asymmetric on either side of the plane P that is orthogonal to the axis of the roller and comprises this circle of said surface of revolution having a minimum extreme diameter. The top roller 3 is of the “barrel” type. This roller comprises a straight axis 9 and a surface of revolution 10. This surface of revolution comprises a circle of maximum diameter comprising the point 11. The surface of revolution of this roller is asymmetric on either side of the plane P that is orthogonal to the axis 9 of the roller and comprises this circle of maximum diameter. The plane P comprises both the circle of minimum diameter of the roller 2 and the circle of maximum diameter of the roller 1. These rollers have complementary shapes with respect to one another and their surfaces of revolution are at a distance from one another by a constant spacing over the entire conveying zone, this spacing being equal to the thickness e of a sheet of glass. The dashed lines on the right-hand side of the figure represent the shape that the surfaces of revolution of the two rollers would have toward the right if they were symmetric with respect to a plane P, which would then be located slightly farther to the right in the figure.

[0029] FIG. 2 is a schematic depiction in side view (transverse view) of a bending and tempering machine to which the invention more particularly applies. A sheet of glass runs through and is heated in a furnace, then passes through an upward shaping bed, and then, at the outlet, through a secondary cooling zone. The sheet of glass 81, which is initially flat, firstly crosses a heating zone 82 of a tunnel furnace (the arrow in the furnace indicates the conveying direction, which is also the longitudinal direction), through which it is carried on a horizontal conveyor 83 moved by a bed of straight motorized rollers 64 that are aligned in a plane. At the outlet of the temperature-raising furnace, the glass is at its deformation temperature, allowing the thermal bending thereof. The sheet of glass 81 then passes into a shaping zone comprising a bed of upper rollers 67 and a bed of lower rollers 69 that are mounted with an upward profile in the form of a circular arc in side view. The sheets of glass pass between the two rollers of pairs of rollers, said pairs being disposed one after another on the path of the sheets of glass. For most of the pairs of rollers, the axis of the first roller is at a lower level than the axis of the second roller. The running sheets of glass are squeezed and shaped between pairs 73 of rollers of these two beds of rollers. The bed of rollers 67 and the bed of rollers 69 thus form an upward shaping bed that conveys the sheet of glass 81 in the same direction as the conveyor 83. The sheets of glass 81 are bent, starting at the first pairs 73 of rollers, in the transverse direction as shown in FIG. 1, and in the longitudinal direction corresponding to the upward circular arc shape of the beds of rollers. This shaping is followed by cooling between the two beds of rollers, in particular tempering. To this end, nozzles blow cool air between the rollers onto the two faces of the sheets. These nozzles are connected to box structures 70 that supply them with the necessary air. The glass is thus fixed just after it has been bent. The air is blown starting at the first pairs of bending rollers. On leaving the shaping and tempering bed, the sheets of glass that have become rigid tip onto a conveyor 71. The sheets of glass 81 are then evacuated by a flat conveyor 72 that passes through a secondary cooling zone 93.