Abstract
A frame for supporting a sheet of glass, referred to as a suction frame, includes a contact path for receiving the periphery of the underside face of the sheet of glass, and includes a suction system able to apply suction to the underside face of the sheet in order to enhance the retention of the sheet by the frame. This frame may form part of a device for the hot-bending of the sheet and convey the sheet with high acceleration or deceleration through a heating enclosure for the purposes of the hot-bending of the sheet.
Claims
1. A suction frame for supporting a sheet of glass, comprising a contact path for receiving a periphery of an underside face of the sheet of glass, and comprising a suction system adapted to apply suction to the underside face of the sheet of glass in order to enhance a retention of the sheet of glass by said suction frame.
2. The suction frame as claimed in claim 1, wherein the suction is applied through the contact path of the suction frame.
3. The suction frame as claimed in claim 2, wherein the suction is applied through local suction zones of the contact path of the suction frame.
4. The suction frame as claimed in claim 1, further comprising at least one closed suction chamber under the contact path, orifices passing through the suction frame between the closed suction chamber and the contact path, the closed suction chamber being connected to the suction system.
5. The suction frame as claimed in claim 1, comprising a blowing system adapted to blow through at least a local blowing zone of the contact path of the suction frame.
6. The suction frame as claimed in claim 5, further comprising at least one closed blowing chamber under the blowing zone of the contact path orifices passing through the frame between the closed blowing chamber and the contact path, the closed blowing chamber being connected to the blowing system.
7. The frame as claimed in claim 1, further comprising a plenum positioned below the central zone of the underside face of the sheet in order to impart thereto a pressure higher than atmospheric pressure.
8. The suction frame as claimed in claim 1, wherein the suction is applied to the central zone of the sheet of glass through the inside of the suction frame.
9. The suction frame as claimed in claim 8, further comprising a plenum positioned under the central zone of the underside face of the sheet of glass so as to be able to impart thereto a sub-atmospheric pressure.
10. The suction frame as claimed in claim 1, further comprising a blowing device allowing air to be blown through the contact path.
11. The suction frame as claimed in claim 1, wherein the suction is strong enough to secure the sheet of glass to the suction frame during an acceleration or deceleration of at least 1500 mm/sec.sup.2.
12. The suction frame as claimed in claim 1, wherein the contact path for the sheet of glass has a width of at least 25 mm.
13. A device for transporting a sheet of glass comprising the suction frame of claim 1 and a conveyor for conveying said suction frame.
14. The device as claimed in claim 13, wherein the conveyor is adapted to confer upon the suction frame an acceleration or deceleration of at least 1500 mm/sec.sup.2.
15. The device as claimed in claim 14, wherein the suction is able to hold the glass in position during an acceleration or deceleration.
16. A device for the hot-bending of a sheet of glass comprising a transport device of claim 13, and a heating enclosure, the transport device allowing the suction frame to be conveyed into the enclosure.
17. The device as claimed in claim 16, further comprising a bending support comprising the suction frame and a bending mold, one of the suction frame and the bending mold being surrounded by the other one of the suction frame and the bending mold when viewed from above, at least one of the suction frame and the bending mold being able to be given a relative vertical movement with respect to the other.
18. A method for transporting a sheet of glass comprising conveying the sheet of glass using the device of claim 13, said conveying comprising an acceleration or deceleration, the suction applied to the sheet of glass by the suction system of the suction frame being in operation during said acceleration or deceleration.
19. The method as claimed in claim 18, wherein the acceleration or deceleration is of at least 1500 mm/sec.sup.2 and less than 7500 mm/sec.sup.2.
20. A method for the hot-bending of a sheet of glass comprising transporting the sheet of glass using the method of claim 18, the suction frame supporting the sheet of glass being conveyed into an enclosure raised to the plastic deformation temperature of the glass, followed by the bending of the sheet.
21. The method as claimed in claim 20, wherein the bending is performed at least partially on the suction frame.
22. The method as claimed in claim 20, wherein the bending is performed on a bending support comprising the suction frame and a bending mold, one of the suction frame and bending mold being surrounded by the other one of the suction frame and bending mold when viewed from above, at least one of the suction frame and bending mold being given a relative vertical movement with respect to the other, so as to cause the sheet of glass to transfer from the suction frame to the bending mold, the suction applied to the sheet of glass by the suction system of the suction frame not being in operation during this transfer.
23. The method as claimed in claim 20, wherein the conveyor causes the suction frame to move alternately from one position to another in the enclosure, pausing in each position.
24. The method as claimed in claim 21, wherein the bending is performed by gravity bending.
Description
[0025] FIG. 1 depicts a suction frame 200 supporting a sheet of glass 201 via a contact path 202. When viewed from above, the suction frame and its contact path have the shape of a ring surrounding an opening 210. This contact path is made up of a refractory fibrous material 205 well known to those skilled in the art for equipping tools that are to come into contact with hot glass. This fibrous material in particular covers the machined upper surface 208 of the suction frame under which there has been constructed a closed chamber 209 capable of being placed under vacuum, said upper surface 208 being pierced. The fibrous material is flexible enough to conform to the shape of the machined upper surface 208 of the suction frame. The inside of the closed chamber 209 is connected to a vacuum-creating system by the duct 203. The suction passes through orifices 204 present in the machined upper surface of the suction frame and then through the fibrous material 205, the latter being designed not to be gastight. It is considered that it too comprises orifices through which the stream of suction air can pass. In this embodiment, the contact path is slightly curved. A small amount of pre-bending may be applied on this suction frame. Another bending tool consists of an additional frame 207 acting as a bending mold, which surrounds the suction frame 200. At the appropriate moment, the suction frame is lowered allowing the additional frame 207 to pick up the glass in order if appropriate to continue the gravity bending. The suction is initiated in order to hold the sheet on the suction frame during the transfer of the glass at high acceleration or deceleration. This transfer time can be put to use for applying gravity pre-bending on the suction frame. Once the glass is in the correct position, the suction is stopped so that the suction frame no longer retains the glass and so that the additional frame can pick up the sheet.
[0026] FIG. 2 depicts a suction frame 300 supporting a sheet of glass 301 via a contact path 303. This contact path is made up of a fibrous refractory material 305 well known to those skilled in the art for equipping tools that are to come into contact with hot glass. This fibrous material in particular covers the upper surface of a ring-shaped metal frame 306 surrounding an opening 311. The metal frame 306 gives the desired shape to the contact path, the fibrous material being flexible enough to conform to the shape of the upper face of the metal frame 306. The frame is connected by its opposite side from the contact path to a plenum 307 forming a volume 308 below the underside surface 309 of the sheet of glass. The plenum is connected to a duct 310 making it possible to generate a vacuum in the volume 308, after a sheet of glass has been set down on the contact path. Thus, the suction is applied to the central zone of the underside face 309 of the sheet, through the opening 311 surrounded by the suction frame. This vacuum accentuates the force applied to the upper face of the sheet 301. The sheet thus rests more firmly on the suction frame and is thus better held in position in spite of the lateral movements of the suction frame.
[0027] FIG. 3 depicts a view from above of a device 250 for bending a sheet of glass comprising a suction frame 251 and an additional frame 252 (acting as a bending mold) surrounding it. The contact path 253 of the suction frame comprises three zones 254 (crosshatched) pierced with orifices so that suction can be applied. The suction is therefore applied through just part of the contact path of the suction frame. Formed under the pierced zone is a closed chamber 255 that can be placed under vacuum by ducts (not depicted) connected to a suction system. The suction is therefore generated in just three local zones connected to a suction system. This localized suction reduces the costs of tooling and simplifies the suction system in the suction frame. The retention effect on the suction frame is sufficient and the system allowing this is less complex.
[0028] FIG. 4 depicts a cross section in side view of a device 219 for bending a sheet of glass 213 comprising a suction frame 211 and an additional frame 212 (acting as a bending mold) surrounding it. The suction is produced in a central zone of the glazing through the inside 214 of the suction frame. A plenum 216 positioned below the central zone of the underside face of the sheet 213 allows a sub-atmospheric pressure to be imparted thereto. This plenum is connected gastightly to the frame 211 so as to be able to sustain the vacuum under the glass. It is connected by a duct 217 to a vacuum-producing system. Blowing is generated at the same time through the contact path of the frame which path is provided with orifices. Specifically, a closed chamber 270 is formed under the contact path and a duct 271 allows it to be connected to a pressurized system allowing air to be blown through orifices of the machined upper surface of the metal frame of the suction frame and through the fibrous material 215 covering same. The material 215 made of refractory fibers softens the contact with the glass. At this stage, the glass 213 is picked up by the suction frame in a raised position, the additional frame 212 having to pick up the sheet later. The objective is to reduce the risk of marking of the glass with the suction frame. Air is blown through the frame to create an air cushion at the zone of glass/frame contact and reduce the risk of marking of the glass. At the same time, suction is applied to the central zone of the glass in order to hold it on the frame.
[0029] FIG. 5 depicts a cross section in side view of a device 220 for bending a sheet of glass 223 comprising a suction frame 221 and an additional frame 222 (acting as a bending mold) surrounding it. The suction is produced through the contact path equipped with orifices 224. This contact path comprises a refractory material 228 made of fibers that softens the contact with the glass. Blowing is generated at the same time in the central zone of the glazing through the inside 225 of the suction frame. A plenum 226 positioned under the central zone of the underside face of the sheet 223 allows a pressure to be imparted to the latter. This plenum is connected gastightly to the frame 221 so as to be able to maintain the pressure under the glass. It is connected by a duct 227 to a pressure-producing system. The objective of the blowing is to reduce the risk of marking of the glass with the suction frame. A closed chamber 280 is formed under the contact path and a duct 281 allows this to be connected to a vacuum system allowing air to be sucked through orifices in the machined upper surface of the metal frame of the suction frame and through the fibrous material 228 covering it. Suction is applied through the frame to hold the glass in position at the zone of glass/frame contact and at the same time air is blown onto the central zone of the glass to create an air cushion and reduce the relative weight of the glass on the contact path.
[0030] FIG. 6 depicts a suction frame 230 supporting a sheet of glass 231 via a contact path 232. This contact path is made up of a fibrous refractory material 235 covering the machined upper surface 236 of the suction frame under which two closed chambers 237 and 238 have been constructed. The chamber 237 can be placed under vacuum so as to apply suction to the glass through the machined surface pierced with orifices 239 and through the interposed fibrous material 235. The purpose of this suction is to reinforce the retention of the glass on the suction frame. The inside of the closed chamber 237 is connected to a vacuum-creating system via the duct 240. The suction is applied through orifices 239 present in the machined upper surface 236 of the suction frame and through the fibrous material 235. The chamber 238 contiguous with the chamber 237 may be pressurized by a duct 241. A blowing of air is then applied through orifices 242 pierced in the machined surface 236 and through the interposed fibrous material 235. The objective is to reduce the risk of marking of the glass as a result of contact between the glass and the suction frame. Suction is applied through the frame in order to hold the glass in position at the zone of glass/frame contact corresponding to the chamber 237. On this same suction frame 230 air is blown through the contact path 236 above the chamber 238 to create an air cushion and reduce the risk of marking of the glass.
