AU725900B2 - Method and apparatus for controlling bending of a glass in a glass bending oven - Google Patents
Method and apparatus for controlling bending of a glass in a glass bending oven Download PDFInfo
- Publication number
- AU725900B2 AU725900B2 AU20969/97A AU2096997A AU725900B2 AU 725900 B2 AU725900 B2 AU 725900B2 AU 20969/97 A AU20969/97 A AU 20969/97A AU 2096997 A AU2096997 A AU 2096997A AU 725900 B2 AU725900 B2 AU 725900B2
- Authority
- AU
- Australia
- Prior art keywords
- bending
- glass sheet
- box
- glass
- furnace
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Ceased
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B23/00—Re-forming shaped glass
- C03B23/02—Re-forming glass sheets
- C03B23/023—Re-forming glass sheets by bending
- C03B23/025—Re-forming glass sheets by bending by gravity
- C03B23/027—Re-forming glass sheets by bending by gravity with moulds having at least two upward pivotable mould sections
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Organic Chemistry (AREA)
- Re-Forming, After-Treatment, Cutting And Transporting Of Glass Products (AREA)
Description
WO 98/39261 PCT/FI97/00141 METHOD AND APPARATUS FOR CONTROLLING BENDING OF A GLASS IN A GLASS BENDING OVEN The invention relates to a method and apparatus, by means of which bending produced by the force of gravity in a glass sheet bending furnace is controlled by restricting the increase of temperature on a required area in the glass sheet.
On using an edge mould for glass sheet bending, the problem has been that due to gravity the glass sheet bends too much, generally in the centre of the sheet before the glass sheet edge areas have even reached the required degree of bending.
That is the case especially on bending big size glass sheets with an edge mould. That kind of glass sheets are typically bent in a one-chamber or multi-chamber furnace, where heating is carried out with radiation elements above the glass sheet.
The problem is reduced in connecting radiation elements above the area of strongest bending only.
For reduction of the problem accessories are known, among others different kinds of plates to shade the radiation of heating elements above the glass sheet, where excessive bending could take place. Also massive metal plates under the glass sheet have been locally used for reduction of glass sheet heating.
The disadvantage of these optional accessories is slowed-down heating speed because of the glass breaking risk. The massive plate and shading cause differences of temperature in the Sglass sheet and that is why maximum heating speed cannot be applied in temperatures of 20° 500°C. Only at temperatures over 500°C even great differences of temperature can be maintainted and said accessories will not be a disadvantage. They make the heating time longer and the massive plate lengthens also the cooling time. These facts show also that due to the above accessories the bending process uses more energy.
WO 98/39261 PCT/F197/00141 2 With a method and apparatus according to this method the current problem is solved and the invention is characterized in what is presented in the patent claims.
The object of this invention is to produce a small-mass cooling surface, which is at least in the bending section and in connection with the bending glass sheet causing differences of temperature into the glass. A box type horizontal surface, made for instance of two metal sheets and placed under the glass sheet, does not hinder the glass sheet from getting heated. The surface can be set in function advantageously only by blasting compressed air at a certain time. When fed air is steered into and out of the box type construction, it does not cause any interference of flow in the furnace. By means of the temperature and quantity of compressed air the surface temperature can be adjusted and thus the effect on the glass sheet. Cooling by the box is used only at the final stage of heating, when harmful bending would begin, at a temperature over 550'C. Thus real heating phase can be done quickly.
By means of the method and especially in connection with laminated windshields, it is possible to make sure that on bending two glass sheets the centre portion of the lower sheet does not bend excessively due to the force of gravity.
This can easily happen if trying to restrict bending by prior known means from the glass sheet upper side, for instance by shading resistance elements. Then the upper one of the overlapping glass sheets may even get less heated than the lower sheet and remain more straight.
The most advantageous embodiment is a box underneath the glass sheet, whereat much surface is achieved with as little mass as possible. Such a box can be fixed in the edge mould, the edge mould chassis or the bending section of the furnace.
It can be also built in the bending section of a series furnace, into which the edge moulds move, for instance, in WO 98/39261 PCT/FI97/00141 3 turns along a track and whereby mould and glass sheet can stop at it and move across it.
In the following the invention is disclosed with reference to the enclosed drawing, where Fig. 1 is a side view of a glass sheet in an edge mould.
Fig. 2 is a diagonal view of a bent glass sheet in an edge mould in the furnace.
Figure 1 shows a hinged edge mould on which glass sheet 1 is installed. Holders 4 of the mould edges are by means of joints 5 hinged to be turning in a way known as such. Due to weights 6 the glass sheet rests at first on several points till the glass sheet bending and proper design of the weights 6 finally turn holders 4 up to their overrunning stops, whereat the edges of the glass sheet middle portion sink onto the mould holders 8.
A box according to the invention is placed in the mould so that it is under the glass sheet about in the glass sheet middle portion.
Figure 2 is a diagonal representation of the mould in a 1chamber furnace, which is a typical bending furnace of large windshields. The glass has got bent to its final shape according to the edge mould. In both glass sheet edges there is a small bending radius due to which heat must have been directed at the most to these glass edge portions, so that bending has been possible by the force of gravity. The glass sheet gets heated excessively also in its middle portion which is still without support. By means of a cooled box 3 as per this invention excessive bending of the glass sheet from its middle portion has been prevented in keeping the glass temperature lower. Then the glass sheet stiffness in its middle portion has been retained and there has been no excessive sagging.
WO 98/39261 PCTFI97/00141 4 Cooling compressed air has been conveyed into box 3 when the temperature of glass middle portion has exceeded 590°C. For conveyance of compressed air there are connections 7 in the box. The compressed air is steered off the box along a tube to the outside of the furnace in order to avoid disturbing flows in the furnace. The box causes a cooling effect and heat radiation that is shifted over from the glass to the box and, to a low degree, as convection between these two.
The distance of box 3 can be adjusted with respect to the glass sheet, whereat a certain adjustment of capacity is achieved. It is also possible to adjust the compressed air quantity or the temperature and achieve different cooling effects on the glass. If necessary, with the shape and size of the box different cooling effects are produced, likewise in using several boxes disposed in required spots, if necessary.
Instead of a 1-chamber furnace a box as per the invention can be used in a series furnace. It can be installed firmly into the bending section, whereat the mould and glass sheet get along a track to its upper side or, transferably, into the bending section, whereat it is moved, when needed, to the glass lower side by a mechanism.
A box as per the invention can also be fixed to an edge mould moving along the track in a series furnace, where in the bending section compressed air is connected to it. It can also be in the mould chassis and from there be adjusted into different levels.
Instead of the box a plate can be used with a heat conductive coil underneath, through which the compressed air passes.
V
Claims (9)
1. A method to control glass sheet bending in a glass sheet bending furnace, where the glass sheet is supported for instance, with an edge mould 4,8) and the bending takes place mainly due to the force of gravity, characterized in that the distribution of glass temperature during bending is influenced by blasting air into a substantially flat small- mass box placed in the glass bending direction either on the upper or lower side of the glass sheet in the furnace, in order to produce a cooling effect on the glass sheet (1) through radiation and convection.
2. A method according to claim 1 characterized in that air is conveyed to the box when the glass temperature is over 450°C.
3. A method according to claim 1 and 2 characterized in that the box size, shape or quantity is chosen according to the glass type.
4. A method according to any of the previous claims 1 3 characterized in that the box is placed on the opposite side of glass sheet with respect to the heating elements.
A method according to any of the previous claims 1 4 characterized in that in a 1-chamber furnace the box is installed in connection with the edge mould for instance.
6. A method according to any of the previous claims 1 3 characterized in that in a multi-section series furnace the box is installed into the bending section, either as a fixed equipment or as an equipment moving along a track with the mould.
7. An apparatus to control glass sheet bending in a glass sheet bending furnace, where the glass sheet is supported, instance, with an edge mould and the bending takes PAce mainly due to the force of gravity, characterized in AMENDED S&-1,_T P~Il /J 7/1 4 1 2 3 -03- 1999 6 that the apparatus includes one or several substantially flat small-mass boxes placed in the glass sheet bending direction either on the upper or lower side of the glass sheet and said box having connections for compressed air piping in order to convey air in and out of said box during glass bending for generating cooling radiation and convection from said box to the glass.
8. An apparatus according to claim 7 characterized in that the box is flat in the glass sheet direction and builtand to be firmly fixed to the mould
9. An apparatus according to claim 7 characterized in that in the glass sheet bending furnace the box is placed in the bending section and takes its position or is moved along a track to the connection of the mould in said section. AMFNnFn cwnc
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
PCT/FI1997/000141 WO1998039261A1 (en) | 1997-03-04 | 1997-03-04 | Method and apparatus for controlling bending of a glass in a glass bending oven |
Publications (2)
Publication Number | Publication Date |
---|---|
AU2096997A AU2096997A (en) | 1998-09-22 |
AU725900B2 true AU725900B2 (en) | 2000-10-26 |
Family
ID=8556677
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
AU20969/97A Ceased AU725900B2 (en) | 1997-03-04 | 1997-03-04 | Method and apparatus for controlling bending of a glass in a glass bending oven |
Country Status (3)
Country | Link |
---|---|
EP (1) | EP0970023A1 (en) |
AU (1) | AU725900B2 (en) |
WO (1) | WO1998039261A1 (en) |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE10105200A1 (en) | 2001-02-06 | 2002-08-14 | Saint Gobain | Method and device for bending glass sheets in pairs |
DE10257972B3 (en) * | 2002-12-12 | 2004-06-17 | Saint-Gobain Sekurit Deutschland Gmbh & Co. Kg | Producing edge compression stresses in lamination glass by cooling, places heat sink close to edge, without making contact |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB821180A (en) * | 1956-06-28 | 1959-09-30 | Pittsburgh Plate Glass Co | Glass bending lehr |
US2984943A (en) * | 1956-02-29 | 1961-05-23 | Libbey Owens Ford Glass Co | Method of heating and bending glass sheets |
-
1997
- 1997-03-04 WO PCT/FI1997/000141 patent/WO1998039261A1/en not_active Application Discontinuation
- 1997-03-04 AU AU20969/97A patent/AU725900B2/en not_active Ceased
- 1997-03-04 EP EP97906197A patent/EP0970023A1/en not_active Withdrawn
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2984943A (en) * | 1956-02-29 | 1961-05-23 | Libbey Owens Ford Glass Co | Method of heating and bending glass sheets |
GB821180A (en) * | 1956-06-28 | 1959-09-30 | Pittsburgh Plate Glass Co | Glass bending lehr |
Also Published As
Publication number | Publication date |
---|---|
EP0970023A1 (en) | 2000-01-12 |
WO1998039261A1 (en) | 1998-09-11 |
AU2096997A (en) | 1998-09-22 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
FGA | Letters patent sealed or granted (standard patent) | ||
MK14 | Patent ceased section 143(a) (annual fees not paid) or expired |