JPH02252631A - Production of bent glass plate - Google Patents

Abstract

PURPOSE:To eliminate the distortion of a reflection image by heating a glass plate by normal heating process, further heating the circumference region of the plate at a specific heat-transfer coefficient and forming the plate in curved form. CONSTITUTION:A glass plate having a thickness of <=5mm is heated by normal heating process and, at the same time, the circumference of the plate within 150mm from the edge is heat-treated at a heat-transfer coefficient of 5-50/m<2>.h. deg.C by blowing hot air from a furnace with a fan or a compressor and a double nozzle and the heated plate is pressed with a pair of conventional concave press faces. The pressed face is quenched by blasting air to form a curved glass plate having a curvature of <=2,000mmR, giving a reflection image free from distortion and having an irregularity of the part near the edge (especially the deformation of deflected concave part) of about 0.05mm or less.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a single-pane, double-layer, or laminated glass, either raw or tempered, for use in vehicle window glasses such as automobiles, architectural window glasses, etc. Eliminates the phenomenon in which the reflected image appears distorted near the edge of the screen.1. The present invention relates to a method for manufacturing a bent glass plate.

[Prior Art] Conventionally, in various types of bent glass, especially tempered glass, the smaller the curvature of the bend, the more distorted the reflected image near the edge of the glass plate. Due to the increasing demand for bent glass, there is a demand for good-looking automobile window glass in particular.

Therefore, various bending forming methods have been devised in an attempt to solve similar optical distortions such as overlapping. That is, JP-A-61-1313111 describes a press bending apparatus for plate glass, and in the case of automobile window glasses, etc., the curvature is large at the periphery and small at the center. As shown in the figure, each part has a different curvature, and optical distortion tends to occur in parts with large curvature, that is, rounded parts. An auxiliary press is placed between the mold and the mold so that it can be moved up and down, and this auxiliary press is used to pre-form the part that will become the small radius before forming the temporary glass between the upper and lower molds. , a method is described in which the plate glass and the molding surface of each mold are prevented from coming into contact with each other unevenly, and the contact pressure is suppressed from becoming large in some areas.
Publication No. 91025 describes a plate glass press molding apparatus, in which a drooping part is created in the peripheral part of the plate glass where the ring mold did not hit, and a reflection distortion called highlight is applied to this part. In order to prevent optical distortion caused by the formation of recesses in the member corresponding to the ring mold so as not to interfere with the conveyance roller, a ring mold consisting of a plurality of divided bodies located above the conveyance roller is used.
- The temporary glass taken up from the transport roller is received by the ring mold in which each divided body is combined, and press-molded between it and the upper mold in this state to form a concave part. A method for eliminating the need for molding the entire circumference of the plate glass using a ring mold is described, and furthermore, regarding self-weight bevelling, Japanese Patent Application Laid-Open No. 61-27
Publication No. 0228 discloses that the top surface of the mold is discontinuous at the position of the opening of the groove, and this discontinuity does not come into contact with the plate glass, and the mold is designed to prevent optical distortion due to reflected light from occurring at the peripheral edge of the plate glass. The upper surface of the periphery is continuous all the way around, and the center part is a recess or space, and the conveyor rows and utensils placed above the molds can be moved up and down, and when lowered, the molding By being sized to fit within the recess or space of the mold, the contact pressure between the conveyance roller and the temporary glass can be reduced and the contact time can be shortened, so the part that comes into contact with the conveyance roller can be cooled and suppressed compared to the surrounding area. It is stated that
No. 327 discloses that before heating a glass plate, a removable heat ray reflective coating is formed on the longitudinal side edge of the glass plate in advance to lower the temperature of this area and reduce sag. The molding method is described, and in addition,
Japanese Patent Publication No. 55-42939 describes a method for bending a glass plate to suppress sagging and doubling, especially in the central part, by using self-weight bevel, and JP-A No. 56-22643 describes a method for bending a glass plate by using self-weight bevel. By providing a conductive path on the surface of the glass sheet, each of the adjacent sheet glass portions of the bent sheet glass becomes a curved shape, instead of the sheet glass being bent in the opposite direction to the other curved surface portions along the bending line. It is known that some attempts have been made to do so.

[Problem to be Solved by the Invention 1] As mentioned above, in the conventional bending forming method, especially in the bending forming method with a curvature of 2000 mm R or less, it is not necessary to create a bent glass without distortion of the reflected image near the edge of the glass plate. I was not able to obtain this and was not completely satisfied. 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 there has been a problem in automobile window glass that a bent glass without distortion of the reflected image is desired from an aesthetic point of view.

Means for Solving Problem L] The present invention takes into consideration the conventional problems, and has the following features:
It was discovered that when a glass plate is bent and formed, the amount of minute deformation that occurs near the edge of the plate, especially within a certain range, affects the distortion of the reflected image. It was discovered that the desired purpose could be achieved by heating and bending the material.

That is, when manufacturing a bent glass plate with a curvature of 2000 mm R or less, in addition to normal heating, the present invention applies a heat transfer coefficient during heating to the vicinity of the edge of the blank of the bent glass plate. 5~50Keal/m-h・℃ than other places
A method for producing a bent glass plate, characterized in that the bending glass plate is heat-treated to a large extent within a range of 150 mm from the edge of the glass plate, and further characterized in that the vicinity of the edge of the bent glass blank is within 150 mm from the edge of the glass plate. The present invention provides a method for manufacturing a bent glass plate.

Here, we used a bent glass plate with a curvature of 2000 es R or less because, for example, a nearly flat tempered glass plate of about 2500 es R would have unevenness if it was a normally used automotive window glass. This is because the concave shape of the reverse warp is small and distortion of the reflected image is hardly a problem.

In addition, the heat transfer coefficient during the heating is set to 5 to 50/m2・h・
The reason why it is set at 5 Kcal/m2·h·°C is because if it is less than 5 Kcal/m2·h·°C, reverse warp-like depressions will appear in the above-mentioned irregularities, making it impossible to eliminate the distortion of the reflected image and hardly exhibiting any effect. , and if it exceeds 50 Keal/Oboro 2・h・℃, the glass plate to be treated will cause local deformation or deterioration of the surface condition, and preferably 10 to 30 Kcal/m
The temperature range is 2.11°C. The heat transfer coefficient can be controlled by blowing air in the furnace near the edge of the plate using, for example, a fan or compressor and a double nozzle. For the attachment, a copper plate with a diameter of 30mm and a thickness of 3cm is used with a thermocouple in the center, and for the blowing, the surface temperature of the plate due to air is measured and determined from the temperature change, and for this blowing, the air is adjusted and adopted. It is something to do.

Furthermore, near the edge of the plate, especially 150mm from the edge of the plate.
The reason for this is that unevenness, especially a reverse warp-like concave phenomenon, is likely to occur within approximately 1000 mm from the edge of the plate in the case of a normally used size of automobile window glass, for example. This is because, for example, the concave phenomenon causes distortion of the reflected image.

In particular, unevenness tends to occur in the area centered at 20 to 100 am from the edge of the plate.

Furthermore, the amount of micro-unevenness deformation is approximately 0.05mm.
It is best to keep the value below 0 near the edge of the glass plate.
This is because if it exceeds -05 mm, the distortion of the reflected image will worsen, which may impair the aesthetic appearance of car window glass, for example, and of course it will not be possible to perform more accurate construction, which will subtly affect the integrity of the installation. This is because. In particular, when a bend with a certain curvature is reversely curved, the distortion of the reflected image becomes significant. A preferable amount of the deformation is 0.03 m or less.

Furthermore, the glass plate may be inorganic or organic! It goes without saying that it can be either colorless or colored, and includes raw or reinforced veneer, multilayer, and laminated glass.

Note that the present invention is particularly useful for those having a plate thickness of 5 mm or less.

[Function] As mentioned above, the method for manufacturing a bent glass plate of the present invention includes:
In particular, when manufacturing a bent glass plate with a curvature of 2000 svi R or less, in addition to normal heating, the heat transfer coefficient is set to a specific value near the edge of the plate, especially within 150 mm from the edge of the plate. By controlling the heat treatment, the curved glass plate is made such that the amount of deformation is within 0.05 mm, with the occurrence of irregularities, especially reverse warped concave parts, compared to the designed curved surface. .

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 limiting the area where it affects the glass plate, concave portions where the curvature changes discontinuously, especially in automobile window glass, such as door window glass, can be reduced by concave mirrors. As a result, reflection image distortion occurs, and the phenomenon of uneven distortion that is not symmetrical near the edges in the left and right width direction is eliminated, and the attachment of the glass plate to the window frame is adjusted in time. This improves the performance of the vehicle and improves its aesthetic appearance, with no creases when going up and down, which ultimately leads to increased driving safety.

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

Fire 1" LL Length 92 Length 9 Width 560 mm, plate thickness 3.5 m While heating a glass plate of Arashi to about 660°C, a cylindrical medium is placed near both sides of the plate within about 130 mm from the edge of the glass plate. A fan is installed with a nozzle-shaped tip to create a turbulent flow on the plate surface, and film transfer is achieved with a heat transfer coefficient of approximately 5 Kcal/12 h.
After heat treatment at a controlled temperature of °C, molding was performed using a pair of conventional concave-convex pressing surfaces. Thereafter, air was blown to rapidly cool the glass plate to obtain a bent tempered glass plate with a curvature of 1600 m1R.

The amount of deformation of the obtained bent tempered glass plate was measured using a stylus-type dial gauge with a span of about 70 shoes. A panel drawn on a lattice with a length of 3 cs is projected on the surface of the bent tempered glass, and the reflected image is photographed, and on the photograph, the line per unit length of the panel is about 1.6 times or more. Those with a line per unit length of approximately 1.3 times or less were similarly marked as acceptable with a 0 mark.

As shown in R1, the results were extremely good, with the amount of deformation being 0.02 layer 1 or less in all parts, and no distortion of the reflected image.

1.1 In the process of heating a glass plate of the same size as in Example 1 to about 670°C, in addition to normal heating, a double nozzle was used especially near the edge of the glass to create a heat transfer barrier. 10Kca
A bent tempered glass plate with a curvature of about 1400 mm R was obtained by a gas hearth construction method in which air with an atmospheric temperature in the furnace was blown at a pressure of mm to give a heating temperature of 1/Peng 2 h C.

As a result of investigation using the same investigation method as in Example 1, as shown in Table 1, all deformations near the edges of the obtained bent tempered glass plate were 0.03 s + m or less, and distortion of the reflected image was also observed. The result was very good and similar to Example 1.

Sparrow - And 1 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 table, the results were also extremely good.

Corresponding to the example, the same glass plate was adopted and bent and formed using a normal press surface.The results were evaluated using the same investigation method as in the above-mentioned example. are shown in Table 1 as comparative examples.

In each of the obtained bent tempered glass plates, the curved four-part deformed wall near the edge of the plate was about 0.20 to 0.80 mm, which was about 10 mm.
The size of the reflected image is from 10 times to several tens of times larger, and distortion of the reflected image also occurs, and improvements are desired.

Note that the same results as described above were obtained for raw boards. Furthermore, when manufacturing a bent tempered glass sheet, it may be necessary to adjust the heat transfer coefficient near the edge of the sheet to be larger or smaller than before during rapid cooling, but this does not pose any particular problem in manufacturing.

Effects of the Invention As described above, according to the present invention, the curvature is 20001 islands R
When manufacturing the following bent glass plates, in the heating process, by heating the glass plate while imparting a specific heat transfer coefficient near the edge, unevenness near the edge of the plate, especially concavities due to reverse warping, etc. It is possible to obtain a bent glass plate in which the amount of deformation is 0.05 mm or less, preferably 0.03 mm or less, and the reflected image is not distorted, making it extremely safe as a window glass for automobiles, and having a good appearance. It is also possible to provide a bent glass plate that has an aesthetic appearance.

Claims (2)

[Claims] (1) When manufacturing a bent glass plate with a curvature of 2000 mmR or less, in addition to normal heating, the heat transfer coefficient during heating is determined from other places near the edge of the blank plate of the bent glass plate. A method for manufacturing a bent glass plate, characterized by carrying out a heat treatment in a range of 5 to 50 Kcal/m^2·h·°C. (2) The method for manufacturing a bent glass plate according to claim 1, wherein the vicinity of the edge of the bent glass blank is within 150 mm from the edge of the glass plate.