Stock material or miscellaneous articles – Structurally defined web or sheet – Edge feature
Patent
1997-11-24
1999-08-17
Jones, Deborah
Stock material or miscellaneous articles
Structurally defined web or sheet
Edge feature
428 34, 428137, 428210, 428410, 428417, 428426, 428432, 428437, 156153, 65104, 65106, 65111, 65114, 65115, B32B 2302
Patent
active
059391758
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to a method of finishing heat-reinforced plate glass and edge regions thereof which are formed by a manufacturing method using or not using suspender metals, and which may be used for fire doors and fire windows, and more particularly to a method of finishing heat-reinforced plate glass and edge regions thereof having received heat reinforcing treatment over entire surfaces thereof.
BACKGROUND 0F THE INVENTION
Where plate glass is used for fire doors and fire windows, the glass must have high edge strength in order to prevent heat cracking of the plate glass. (A thermal expansion occurring in a central region of glass when heated applies a tensile stress to edge regions of the plate glass supported by a window frame or the like, and cracking is caused by the tensile stress exceeding the edge strength of the plate glass).
Known plate glass for fire prevention includes wire glass, and laminated glass having an intermediate layer formed of hydrated alkali silicate. The former may have transparency impairment, with the wiring mounted inside obstructing view. The latter may have transparency impairment, with the intermediate layer foaming up with a heat change and becoming opaque. Soda lime glass having received heat reinforcing treatment may be cited as being free from such a problem.
Heat reinforcing treatment is a method executed by heating plate glass in a temperature range (about 760.degree. C.) far exceeding the softening point of glass (720-730.degree. C.), and blowing cooling air under a very high back pressure of 950 mmAq to a continuous air cooled portion. However, with such heat reinforcing treatment of plate glass, although a predetermined edge strength may be given, the air blown under high pressure to the plate glass heated in the high temperature range exceeding the glass softening point as noted above could result in loss of flatness and create warping to bring about inconveniences in image reflection.
Conventionally, heat-reinforced plate glass of this type includes glass plate having curved edges protruding outwardly in directions along the plane of the plate glass, progressively toward the middle position in the direction of thickness of the plate glass.
According to the conventional heat-reinforced plate glass noted above, in order to be usable for fire doors or fire windows, it is necessary to carry out the above heat reinforcing treatment by heating the plate glass in the temperature range (about 760.degree. C.) far exceeding the softening point of glass (720-730.degree. C.), and blowing cooling air under the very high back pressure of 950 mmAq to a continuous air cooled portion. This heat reinforcing treatment results in the inconvenience noted above (i.e. a loss of flatness of glass surfaces and warping to impair image reflection).
To eliminate this inconvenience (surface non-flatness and warping), a heat reinforcing treatment (hereinafter called simply low-temperature heat reinforcing treatment) may be carried out by lowering the heating temperature and the back pressure of air blown from the values in the conventional heat reinforcing treatment. Then, sufficient edge strength cannot be secured, and thermal distortional stress concentrates on edge regions, particularly polished corners, of the plate glass when exposed to the heat of fire or in fire prevention testing. Particularly where the plate glass has curved end surfaces protruding outwardly along the direction of the plane, a new problem arises that the plate glass tends to break in time of fitting the plate glass, under a working stress due to the weight of the plate glass itself applied to forward ends (portions of the curved shapes protruding most outwardly) of the end surfaces. Generally, plate glass is mounted on weight-receiving rubber elements (setting blocks) laid in two 1/4 positions from the opposite ends of the lower edge. However, incombustible hard blocks are often used as the setting blocks used for fire prevention purposes. In that case, there arises a problem that a
REFERENCES:
patent: 3843472 (1974-10-01), Toussaint et al.
patent: 4182619 (1980-01-01), Greenhalgh
Patent Abstracts of Japan vol. 096, No. 009, Sep. 30 1996 & JP 08118220 A (Nippon Sheet Glass Co.Ltd), May 14 1996.
Patent Abstracts of Japan vol. 097, No. 007, Jul. 31 1997 & JP 09 071429 A (Nippon Sheet Glass Co. Ltd.), Mar. 18 1997.
Bahta Abraham
Jones Deborah
Nippon Sheet Glass Co. Ltd.
LandOfFree
Method of finishing heat-reinforced plate glass and edge regions does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method of finishing heat-reinforced plate glass and edge regions, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of finishing heat-reinforced plate glass and edge regions will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-313610