JPH062592B2 - Heat treatment method for glass plate articles - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a heat treatment method for a glass sheet article most suitable for a building window glass such as a high-rise building or a large area opening. Specifically, it increases the breaking strength of glass plate articles to the extent that it does not result in fine grain crushing that does not reach the tempering degree of ordinary tempered glass. We provide glass plate articles that are less likely to drop even if they are not used, and are used for various interior materials such as architectural window glass, furniture furniture, cooking utensils, glass bottles and other glass. It can be widely applied to articles.

[Conventional technology]

Since glass has good transparency and weather resistance, and is cheaper than other materials, it is widely used as architectural window glass, and even residential buildings can use large area window glass. However, as the number of skyscrapers continues to increase year by year, there is an urgent need to further enhance their safety. That is, it is necessary to increase the breaking strength of high-rise and large-area window glass, for example, to improve wind pressure resistance and heat resistance. Further, there is a demand for a material that does not easily protrude from the window frame so that even if it breaks, fragments do not easily drop from a high place.

However, the breaking strength increases with ordinary heat-strengthened glass, but it is a problem because it breaks finely when crushed.With chemically strengthened glass, the breaking strength is large, and even when broken, it is similar to raw glass. Although it shows a crushing pattern, it takes a lot of time for the chemical strengthening process, the production cost becomes high, and the thickness of the compressive stress layer is thin, so when it is damaged for some reason, the damaged part is a raw plate. There is a problem that it has only the same level of strength as the above.

Thus, there is known a glass having a predetermined degree of tempering which is lowered after cooling by using the conventional air cooling method. That is,
Instead of making the value of surface compressive stress smaller than that of conventional heat-strengthened glass, the internal tensile stress is also made smaller so that even when shattered, it does not break into pieces like conventional heat-strengthened glass. Things have been proposed. For example, in Japanese Examined Patent Publication No. 59-25734, a glass plate with a plate thickness of 10 to 15 mm is used.
After heating to 600 ~ 660 ℃, blow hot air of 50 ~ 300 ℃ on the glass plate surface to cool the glass plate to a temperature below the strain point temperature of the glass plate by making it slower than the natural cooling in the atmosphere.
The central tensile stress σt of this treated glass plate is 85 to 200k.
g / cm ² , and a method of controlling so that the ratio σt / σc of the surface compressive stress σc and the central tensile stress σt is in the range of 1.5 to 2.0 is disclosed, and JP-B-61-40608 is disclosed. Describes a glass sheet tempering method and a tempered glass sheet made by this method, wherein the quench gas stream is at least one local gas stream, the local gas stream having a repetition frequency related to a speed at which the glass sheet progresses to a quench station. It is known, for example, that pulsing causes a glass sheet to have a distribution of areas of higher tempered glass interspersed with areas of tempered glass.

[Problems to be solved by the invention]

As described above, in the past, for example, with a glass plate having a plate thickness of 5 mm or more, the temporary strain generated in the glass becomes too large and the degree of strengthening becomes too large, or cracks often occur. There was a problem that the cooling conditions had to be variously limited and, as a result, the time required for production was long, the productivity was poor, and the cost was high. For example, although the heat treatment method disclosed in Japanese Patent Publication No. 59-25734 mentioned above is intended to be solved, the treatment temperature is as high as 600 to 660 ° C., and since it is a glass plate having a relatively large area, deformation and surface property However, there is also a problem that a device for heating the cooling air to 50 to 300 ° C. is necessary. Further, in the method of Japanese Patent Publication No. 61-40608, a pulsating air is passed during cooling, for example, one pulsation is applied every 0.2 seconds, and the pulsation holding time is 0.1 second. Although the aim is to strengthen the glass without edges, even if the stress distribution in a specific portion of the tempered glass is changed, there is still a problem in obtaining a glass sheet having a predetermined degree of tempering.

[Means for Solving the Problems] The present invention has been made in view of the conventional problems described above, in which a glass plate article heated to 550 to 600 ° C. is combined with a cooling medium having a specific heat transfer coefficient. The present invention provides a method for heat treating a glass sheet article, by which glass having a predetermined degree of strengthening can be efficiently obtained by intermittently cooling in a specific cycle.

That is, the present invention provides a glass article having a thickness of 5 to 8 mm to 550 to 6
After heating to 00 ° C, air is intermittently blown at a cycle of 0.5 to 30 seconds, and cooling is performed so that the heat transfer coefficient during cooling is in the range of 50 to 200 Kcal / m ² · hr ・ ° C during blowing. The present invention provides a method for heat treating a glass sheet article, which is characterized by the above.

Here, the heating temperature of the glass plate article is set to 550 to 600 ° C., although it is difficult to obtain a predetermined degree of strengthening because less viscous flow is less than 550 ° C.
By intermittently blowing air at a cycle of 0.5 to 30 seconds, and also by setting the heat transfer coefficient to 50 to 200 Kcal / m ² · hr · ° C when blowing, it is possible to shorten the processing time. It is possible to process at a temperature lower than that.

In addition, the intermittent spraying cycle is set to 0.5 to 30 seconds, preferably 1 to 20 seconds, because if it is shorter than 0.5 seconds, the effect of stopping the air becomes small and cracks easily occur, and if it exceeds 30 seconds, spraying is performed. This is because it takes too much time for production because it is too long, and it becomes difficult to obtain a predetermined degree of strengthening.

Furthermore, when spraying a heat transfer coefficient, 5-200 Kcal / m ² · hr ・
℃, preferably 80 ~ 180Kcal / m ² · hr · ℃ was 50K
If it is less than cal / m ² · hr · ° C, the degree of strengthening will be too small and the effect will be lost, and the time required for production will take too long, and if it exceeds 200 Kcal / m ² · hr · ° C, the degree of strengthening will be too large, This is because cracks are likely to occur during cooling.

When cooling, for example, rather than blowing air to the entire flat surface of the glass plate at the same time, it is better to blow the air to the central portion of the glass plate first and then to spread it to the peripheral portion of the glass plate while shifting the timing. It is preferable, and the timing difference is 0.1-3s
About ec / m is suitable, and if it is less than 0.1 sec / m, there is no great difference from simultaneous spraying, and if it exceeds 3 sec / m, unnecessary stress is applied and rather cracks are likely to occur.

Furthermore, as a means for setting the heat transfer coefficient to 50 to 200 Kcal / m ² · hr · ° C, it is easy to change the air pressure of the air or change the distance between the glass plate and the tip of the air nozzle of the blast head. Needless to say, the diameter of the air nozzle and the nozzle pitch may be changed.

[Action]

As mentioned above, glass articles with a thickness of 5 to 8 mm are heated to 550 to 600 ° C.
By heating to the range of above and setting it to the cooling temperature, the processing time can be shortened and the productivity is improved, but on the other hand, the handy cap that cracks are likely to occur during cooling The problem is solved by also stopping the air instead of constantly spraying, so that a glass article having a predetermined degree of strengthening can be obtained.

To bring about a more effective action, it is necessary to provide a timing difference so that the central portion of the glass plate starts to be cooled earlier than the peripheral portion of the glass plate as described above. It can be prevented as much as possible.

〔Example〕

 An embodiment of the present invention will be described below.

Example 1 A glass plate having a plate thickness of 6 mm and a size of 1000 × 1000 mm ² was heated to 595 ° C., and then blown with air having a heat transfer coefficient of 80 Kcal / m ² · hr · ° C. for 2 seconds, depending on a cycle of stopping the blowing for 2 seconds. In addition to intermittent cooling, 0.5 sec / in the center of the glass
When cooling was performed by blowing air to the peripheral edge of the glass with a timing difference of m delay, cracking during cooling was zero.

When the breaking strengths of the five obtained samples were compared with the breaking strength, the average value of the breaking strength ratios was doubled.

Examples 2 to 5 Examples 2 to 5 are performed in the same manner as in Example 1 under the conditions shown in Table-1, and the results are also shown in Table-1.

Comparative Examples 1 to 5 The same methods as in Examples were carried out, and the conditions and results are shown in Table-1.

The heat transfer coefficient was measured using a copper plate having a size of 25 mmφ and a thickness of 3 mm.

〔The invention's effect〕

As is apparent from the above, according to the present invention,
By performing intermittent cooling at a specific cycle with air having a specific heat transfer coefficient, a glass article with a thickness of 5 to 8 mm can be made into 1.5% of raw sheet glass.
It has a breaking strength of about 2.0 times, and it does not break into fine-grained pieces like ordinary tempered glass, so it becomes a glass with a certain degree of strengthening, making it a safer construction. It can be provided as a window glass for windows, etc., and can be applied to various glass sheets such as a heat ray absorbing or reflecting glass plate as well as other glass articles.

Claims (1)

[Claims] 1. A glass article having a thickness of 5 to 8 mm is heated to 550 to 600 ° C., and then air is intermittently blown at a cycle of 0.5 to 30 seconds, and a heat transfer coefficient at the time of cooling is 50 to 200 Kcal / A method for heat treating a glass sheet article, which comprises cooling in a range of m ² · hr · ° C.