Glass manufacturing – Processes – Reshaping or surface deformation of glass preform
Patent
1998-01-26
2000-04-25
Silverman, Stanley S.
Glass manufacturing
Processes
Reshaping or surface deformation of glass preform
65 24, 65 254, 65 252, 65102, 65106, 65114, 651822, 651821, 65348, 65349, 65350, 65351, 65355, C03B 2700
Patent
active
060530111
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a process with the feature of the introductory part of the preamble of claim 1.
The invention furthermore relates to a system (device) with the features of the introductory part of the independent apparatus claim.
Glass plates are tempered by heating them to a temperature ("tempering temperature") above 650.degree. C. and then quenching them at a temperature which is below the critical temperature, for example less than 300.degree. C., so that stresses which temper the glass form due to the shock cooling.
In the known devices the cost for heating the glass plates and the quenching costs thereof are very high. In particular in the known devices considerable amounts of energy are needed for operating the fan which delivers the heated gases for heating the glass plates.
The object of the invention is to improve glass tempering and the systems provided for this purposes such that the cost in energy and time is reduced and good glass tempering is still achieved.
As claimed in the invention this object is achieved with the features of the main process claim. With regard to the proposed system (device) as claimed in the invention the object is achieved with the features of the independent main apparatus claim.
Because in the invention glass plates are preheated for example together and then heated to the required tempering temperature preferably individually and furthermore quenching to a temperature below the critical temperature is done preferably individually and the glass plates are then cooled for example together to room temperature, large amounts of time and energy are saved, since the heating and cooling zones need only be short. The invention is based on the finding that it is enough for tempering of glass plates if the temperature jump from the tempering temperature, for example of 650.degree. C., to a temperature below the critical temperature, for example, roughly 300.degree. C., takes place quickly to achieve the desired tempering effect. Preheating and cooling to room temperature can then be done slowly without any adverse effect on the tempering of the glass plates. The adverse, nonuniform surface stresses which lead to undulations in the glass plates and which form in the known processes are avoided.
Other details and features of the invention result from the following description of the glass plate tempering system shown by way of example in the drawings.
FIG. 1 shows the overall system in an oblique view;
FIG. 2 shows the heating and quenching zone in a larger view; and
FIG. 3 shows two heating zones and one quenching zone.
The system as claimed in the invention which is shown in FIG. 1 consists of four zones, specifically preheating zone 1, heating zone 2, cooling zone 3 and after-cooling zone 4.
In preheating zone 1 which is housed in closed chamber 5, glass plates 7 standing in shelves, for example compartmented cars 6, are preheated together and heated for example to a temperature of roughly 300.degree. C. Compartmented cars 6 used in preheating zone 1 can have a construction as they are known from EP 603 151 A or EP 704 389 A. Only the bottom and side rollers or sleeve-shaped slide parts of compartmented cars 6 are made of a correspondingly temperature resistant material due to the high temperature stress.
As shown in FIG. 1, compartmented cars 6 are guided to move on rails 8 transversely to the alignment of the compartments which hold glass plates 7 and which are provided in the cars so that a selected preheated glass plate 7 can be delivered to tilt table 9, from which it is conveyed with the inclined position which corresponds to heating zone 2 from preheating chamber 5 to heating zone 2. Tilt table 9 is advantageously made with a support surface executed as an air cushion wall.
According to one embodiment, between preheating chamber 5 in which glass plates 7 are jointly preheated, and heating zone 2 in which glass plates 7 are heated individually for example to a temperature of 650.degree. C., there can be another heating zone 27 in which glass plates 7 are heat
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Colaianni Michael P.
Silverman Stanley S.
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