JPH02258641A - Production of curved thick glass plate - Google Patents

Abstract

PURPOSE:To prevent the development of the distortion of reflection image near the edge part of the subject glass plate having specific thickness and curvature by applying a specific heat-treatment to the part near the edge of the base plate in addition to the conventional heating process. CONSTITUTION:In the production of the subject glass plate having a thickness of >=6mm and a radius of curvature of <=3,000mmR, the following heat-treatment is carried out in addition to conventional heating process. The part near the edge of the base plate preferably within 200mm from the edge of the glass plate is heat-treated at a heat-transfer coefficient higher than that of the other part by 10-65kcal/cm<2>.h. deg.C, the heat-transfer coefficient is maximized at the zone separated from said plate edge part by 20-50mm and the gradient of the coefficient from the peak to the circumferential part is adjusted to <=2kcal/cm<2>.h. deg.C per 1cm.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention relates to the use of single-pane, laminated or laminated glass, particularly 6fi thick, for use in architectural or some vehicle window glass. The present invention relates to a method for manufacturing a thick bent glass plate that eliminates the phenomenon in which a reflected image appears distorted near the edge of the thick bent glass plate.

[Prior Art] Conventionally, in various thick bent glass plates, the smaller the curvature of the bend, the more distorted the reflected image near the edge of the thick glass plate has become. Due to the increasing demand for thick bent glass sheets, there is a demand for glass with good aesthetics, especially for architectural and some vehicle applications.

Therefore, various bending methods have been proposed in an attempt to solve similar optical distortions such as overlapping. That is, JP-A-61-183138 describes a press bending apparatus for sheet glass, and in the case of automobile window glasses, etc., the curvature seems to be large at the periphery and small at the center. However, each part has a different curvature, and optical distortion tends to occur in parts with large curvatures, that is, rounded parts. An auxiliary press is placed between the two molds, and before the temporary glass is formed between the upper and lower molds,
By pre-forming the portion that will become the small radius portion in advance, the plate glass and the molding surface of each mold do not come into uneven contact, and
A means for suppressing the contact pressure by preventing it from becoming large in some parts is described, and Japanese Patent Application Laid-Open No. 61-91
Publication No. 025 describes a press molding apparatus for temporary glass, which produces a drooping part in the part of the peripheral edge of the plate glass that was not touched by the ring mold, and a reflection distortion called a highlight occurs in this part, etc. In both cases, a ring mold consisting of a plurality of divided bodies is placed above the conveyance roller to prevent optical distortion from being formed in the member corresponding to the ring mold so as not to interfere with the conveyance roller. The temporary glass taken up from the glass is held by a ring mold in which each divided body is combined, and press-formed between the upper mold and the upper mold in this state, eliminating the need to form a concave part and forming the entire circumference of the temporary glass. JP-A No. 61-270228 discloses a means for molding with a ring mold, and regarding self-weight bending, Japanese Patent Application Laid-Open No. 61-270228 discloses that the upper surface of the mold is discontinuous at the position of the opening of the groove, and this discontinuity is The continuous part does not come into contact with the sheet glass, and to prevent optical distortion caused by reflected light from occurring at the periphery of the temporary glass, the mold is designed so that the upper surface of the periphery is continuous all the way around and the central part is a recess or space. Among the conveyor rollers, those placed above the mold can move up and down, and are sized to fit within the recess or space of the mold when lowered, thereby preventing contact between the conveyor roller and the temporary glass. It is stated that since the pressure can be reduced and the contact time is shortened, the area in contact with the conveying roller can be cooled and suppressed compared to the surrounding area. Before heating, a heat ray reflective coating that can be peeled off later is formed in advance on the longitudinal side edges of the glass plate,
A molding method is described in which the temperature of this part is lowered to reduce sagging, and in addition,
No. 939 describes a method of bending a glass sheet by bending under its own weight to suppress sagging and doubling, especially in the center, and JP-A No. 56-22643 describes a method for bending a glass plate by bending under its own weight to suppress sagging and doubling. In order to prevent the curved surface from bending in the opposite direction to the other curved surface portions, conductive paths are provided on the surface of the glass sheet so that each of the adjacent temporary glass portions of the bent sheet glass has a curved surface shape. It is known that things are described.

[Problems to be Solved by the Invention] As mentioned above, in the conventional bending forming method, especially in the bending forming method of a thick glass plate having a thickness of 6 fi or more and a curvature of 3000 mm or less, it is not always possible to It was not possible to obtain a thick bent glass plate without distortion of the reflected image near the edge, and it was not very satisfactory. Distortion of the reflected image is particularly likely to occur on both the left and right sides, that is, near the edges of the short sides, and for architectural and some vehicle window glasses, thick bent glass plates that do not distort the reflected image are desired from an aesthetic point of view. There was a problem that

[Means for solving the problems] The present invention has been made in view of the conventional problems,
When a thick glass plate is bent and formed, near the edge of the thick plate,
In particular, we discovered that the amount of minute deformation that occurs within a specific range affects the distortion of the reflected image, and in addition to the normal heat treatment, we heated the area by limiting the heat transfer coefficient by forced convection, and furthermore, we It has been discovered that the desired purpose can be achieved by heating and bending while limiting the gradient of the heat transfer coefficient from this center to the surrounding area.

That is, in the present invention, the plate thickness is 6n or more and the curvature is 30
When manufacturing a thick bent glass plate with a radius of 00 mmR or less, in addition to normal heating, the heat transfer coefficient near the edge of the base plate of the thick bent glass plate is set to be higher than that in other places. 1
Heat treatment is performed to a large extent in the range of 0 to 65 Kcal/w=・h・h・℃, and the heat transfer coefficient is maximized in a region within a range of 20 to 50 m from the edge of the plate, and the maximum ICI from the area to the surrounding area
2 Kcal/m? A method for producing a thick bent glass plate, characterized in that heat treatment is performed with a gradient of less than h゛c, wherein the vicinity of the edge of the thick bent glass blank is within 200i from the edge of glass #Ji. The present invention provides a method for manufacturing a thick bent glass plate characterized by the following.

Here, the thick bent glass plate with a curvature of 300QmmR or less is used, for example, as for the thick bent glass plate with a curvature of about 3500mmR, which is close to flat, it is used for construction of a size normally used or for some vehicles. This is because if it is a window glass, the concavities and concavities are small, and distortion of the reflected image is hardly a problem.

In addition, the heat transfer coefficient during the heating is set to 10 to 65 Kcal/
♂・h−'c is 10Kcal/m”・h−
This is because if it is less than 65Kcal/pus, the concavity of the cane will be reversely curved in addition to the unevenness, making it impossible to eliminate the distortion of the reflected image and hardly exhibiting the effect.
If it exceeds -'c, the glass plate to be treated becomes more likely to undergo local deformation, deterioration of the surface condition, cracking, etc. Preferably 15 to 45 KcaI/1 m -h-"
It is in the range of C.

However, if it is for a short period of time (for example, a few seconds), 6
Exceeding 5Kcal/5L-h・h・℃ is unlikely to cause much of a problem, and the strength-strengthening method does not necessarily need to cover the entire normal heating time; The degree of heating required varies depending on the shape, plate thickness, curvature, etc., and is approximately half or more of the normal heating time for boat fishing. Furthermore, the reason why the area where the heat transfer coefficient is maximum is set in the range of 20 to 50n from the edge of the plate is that the maximum value of the reversal falls within this range, and if it is less than 20mm, deformation etc. It is easy to develop, and if it exceeds 50 dragons, unevenness 1. In particular, this is because an inverted concavity appears, making it difficult to eliminate the distortion of the reflected image, making it almost ineffective.Furthermore, the slope from the area where the heat transfer coefficient is maximum to the surrounding area is 2Kcal per 1cm
/m”・h・h・℃ or less is because if the change exceeds this value, cracks may occur during molding and/or cooling. It is also less susceptible to the effect in the direction from the region shown to the edge of the plate, and is preferably 1.7 Kcal/m"-h-"C or less per law.The control of the heat transfer coefficient described above is This is done by blowing the air in the furnace near the edge of the plate using, for example, a fan or compressor and a double nozzle. Using a copper plate with a diameter of 30n+ and a thickness of 3fl with a thermocouple inserted, the temperature of the plate surface due to air blowing is measured and determined from the temperature change, and the air is adjusted and adopted for blowing. .

Furthermore, the area near the edge of the plate, especially within 200 nm from the edge of the plate, is approximately the same as that of a vehicle window glass of a size that is normally used. This is because it tends to occur within 200 mm from the edge of the plate, and this concave phenomenon, for example, causes distortion of the reflected image. Particularly, unevenness tends to occur in a portion centered at 20 to 50 mm from the edge.

Furthermore, the amount of minute unevenness deformation is preferably about 0.051 or less, and 0.051 in the vicinity of the edge of the glass plate.
This is because if it exceeds 05+lIi, the distortion of the reflected image will worsen, which may impair the aesthetic appearance of window glass for buildings or some vehicles, and of course it will not be possible to perform more accurate construction and the integrity of the installation will be affected. This is because it has a subtle influence. In particular, when the object is bent with a certain curvature and is curved in the opposite direction, the distortion of the reflected image becomes significant.

A preferable amount of the deformation is 0.03 mm or less.

Furthermore, regarding the thick bent glass plate, especially 6 m
The reason why the thickness is m or more is that the thicker the plate, the smaller the curvature,
It is easy to cause reverse warpage and deteriorate the reflected image, and to effectively solve this problem, it is necessary to deal with conditions that are more severe than those for thin glass sheets, and the preferable thickness is 6 to 6. The thick bent glass plate can be either inorganic or organic, and it goes without saying that it can be colorless or colored. J[JL Includes laminated glass.

[Effect]

As mentioned above, the method for producing a thick bent glass plate of the present invention is particularly suitable for producing a thick bent glass plate with a thickness of 6 or more and a curvature of 3000 mm or less, in addition to normal heating. Near the edges, especially 2 from the edge of the plate
By controlling the heat transfer coefficient to a specific value and heat-treating the area within 0.00 Tsuru, unevenness and concavities and convexities are reduced compared to the designed curved surface.
In particular, the appearance of a reversely warped concave portion can be observed when the amount of deformation is 0.05.
This is a thick bent glass plate that is within +am.

In other words, heating, which is a pretreatment for bending and/or strengthening a glass plate, is usually done in a natural convection system, and this natural convection seems to be able to heat the glass plate seemingly uniformly. However, this is not the case, and as a solution to this problem, when it becomes necessary to heat a specific part of the glass plate under different conditions, we actively incorporate the concept of forced convection and improve the heat transfer coefficient. By controlling and restricting the part where the curvature changes discontinuously in thick bent glass such as architectural window glass, the concave part can be avoided. It is possible to attach a thick glass plate to a window frame by eliminating the phenomenon that the reflected image becomes distorted like a concave mirror, and the distortion becomes uneven rather than symmetrical near the edges in the left and right width direction. The consistency over time is improved, and there is no sense of discomfort and the appearance is also improved.

[Examples] Hereinafter, the present invention will be specifically explained with reference to Examples, but the present invention is not limited to these Examples.

While heating a thick glass plate with a length of 920 mm, a width of 560 mm, and a plate thickness of 8 mm to approximately 660°C, a fan is installed in the cylindrical shape near both sides of the glass plate within approximately 150 mm from the edge of the glass plate. The tip is shaped like a nozzle, and the area with the maximum heat transfer coefficient is set at about 25 fi from the edge of the plate to create a turbulent flow state on the plate surface, and the film transfer has a heat transfer coefficient of about 20 Kcal/m"h
”c, and its slope is approximately 1.5Kca per l cm.
After heat treatment at a controlled temperature of 1/m''·h·h·°C, it was molded using a pair of conventional concave-convex pressing surfaces.

After that, cool it by blowing air and reduce the curvature to 2000mm.
A thick bent glass plate of R was obtained.

The obtained thick bent glass plate has a span of about 70I.
The amount of deformation is measured using an Imm stylus type dial gauge, and for example, reverse warpage is expressed as a positive value, and the distortion of the reflected image is determined by measuring the thickness of a panel drawn on a grid with a length of 31. Project it onto the surface of a bent glass plate and take a photograph of the reflected image. If the line per unit length of the panel is approximately 1.6 times or more on the photograph, it will be marked with an x and rejected. Those whose lines per length were approximately 1.3 times or less were marked as acceptable with an O mark.

As shown in Table 1, the results were very good, with the amount of deformation being 0.03 mm or less in all parts, and no distortion of the reflected image.

In the process of heating a thick plate glass plate of the same size and thickness of 10 fl as in Example 1 to about 670 h・℃, in addition to normal heating, the maximum heat transfer coefficient was increased especially near the edge of the glass. The area is set to about 30 fl from the edge of the plate, and the heat transfer coefficient is set to about 20 Kcal/m"・h・h・℃ using a double nozzle.
In addition, the curvature is approximately 3000 mm H by blowing air at the ambient temperature in the furnace using a compressor so that the slope becomes approximately 1.0 Kcal/-・h Pa C.
A thick bent glass plate was obtained.

As a result of investigation using the same investigation method as in Example 1, as shown in Table 1, the amount of deformation in the vicinity of the edge of the obtained thick bent glass plate was all less than 0.03 mIn, and the distortion of the reflected image was also The result was very good and similar to Example 1, with no occurrence.

Length: 1 mm: The results were carried out under the conditions shown in Table 1 in the same manner as in Example 1 and Example 2, and as shown in the cough table, the results were also extremely good.

The same glass plate as in the example was used, and the same glass plate was bent and formed using a normal press surface, and evaluated using the same investigation method as in the above example. The results are shown in Table 1 as a comparative example.

In each of the obtained thick bent glass plates, the amount of deformation of the reversely warped concave portion near the edge of the plate was about 0.70 to 1.10 m, which is about several tens of times larger, and the distortion of the reflected image was also large. This was something that was desired to be improved.

Note that when manufacturing a thick bent glass plate, it may be necessary to adjust the heat transfer coefficient near the edge of the plate to be larger or smaller than before during cooling, but there is no particular problem in manufacturing.

Above, when producing a thick bent glass plate with a curvature of 300h+mR or less, in the heating process, by heating while imparting a specific heat transfer coefficient specifically to the vicinity of the plate edge, The amount of deformation of the unevenness, especially the reversely curved concave portion, is 0°05IIImm or less, preferably 0.03mm.
It is possible to obtain a thick bent glass plate with a thickness of less than mm, and there is no distortion of the reflected image, making it extremely safe for use as window glass for some vehicles, and especially for architectural glass. It is possible to provide a thick bent glass plate that exhibits a beautiful appearance.

[Effects of the invention]

Claims (2)

[Claims] (1) When manufacturing a thick bent glass plate with a thickness of 6 mm or more and a curvature of 3000 mmR or less, in addition to normal heating, near the edge of the blank of the thick bent glass plate, The heat transfer coefficient during heating is 10 to 65Kc higher than other places.
A large heat treatment is performed in the range of al/m^2・h・℃, and the heat transfer coefficient is 20 to 50m from the edge of the plate.
2 Kca per cm from the maximum area to the surrounding area.
A method for producing a thick bent glass plate, characterized in that heat treatment is performed at a gradient of 1/m^2·h·°C or less. (2) The method for manufacturing a thick bent glass plate according to claim 1, wherein the vicinity of the edge of the thick bent glass blank is within 200 mm from the edge of the glass plate.