JPS6358771B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for bending sheet glass, and more particularly to a bent glass that has a sharply bent portion in the shape after being bent and is processed as laminated glass after bending. This invention relates to a bending method for manufacturing. In recent years, there has been a demand for sharply curved plate glass from the standpoint of functionality or design.On the other hand, from the viewpoint of safety, two sheets of glass are bonded together using, for example, a polyvinyl butyral film. Efforts have been made to prevent glass fragments from shattering when broken and to permanently reduce the impact that a human body receives in the event of a collision. For example, Japanese Patent Application Laid-Open No. 55-23093 is known as a method for manufacturing plate glass having sharply bent portions. Japanese Patent Publication No. 55-23093
In this issue, a plate glass is placed on a mold with a desired shape, the entire plate glass is heated,
The entire sheet glass is bent into a gentle shape along the contour mold, and a flexible, elongated conductive heating ribbon insulated from the contour mold is placed close to the portion of the sheet glass that is to be sharply bent. A technique is disclosed in which a heating ribbon is energized to heat a portion of the sheet glass to be bent sharply to a higher temperature than other regions, thereby bending the portion to a sharp angle.

The technique disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 55-23093 is an extremely excellent technique, and the shape or optical properties of the sharply bent portion fully satisfy consumer requirements.

However, if the plate glass is to be used for applications that require particularly high safety, for example, windshield windows for automobiles, the two sheets of plate glass may be bonded together using polyvinyl butyral or the like as described above, and a so-called laminating process may be performed. It is necessary to do it. However, when performing matching processing, it is not only necessary that the plate glass to be processed has an accuracy within the permissible processing error that has been set for each sheet glass, but also that its shape can be approximated with relatively high accuracy. It is necessary that the

In the laminating process, two sheets of glass are bonded together using an interlayer film such as polyvinyl butyral, but if air is present between the glass sheets and the interlayer film, air bubbles are formed during the adhesion process, and the presence of these air bubbles may occur. This significantly impedes the transparency of the laminated glass after it is molded.

In the manufacturing process of laminated glass, the plate glass and the interlayer film are temporarily bonded while degassing, and then they are permanently bonded in an autoclave. It is already known that there is a difference in shape between two sheets of glass that are laminated together.

In other words, when there is a difference in the shape of two glass plates, and as a result, a microscopic space is formed between the two glass plates, degassing the air existing in the space is extremely difficult, and industrial continuous manufacturing is difficult. During the process, degassing is virtually impossible.

When manufacturing laminated glass, which is currently widely used as windshield glass for automobiles, two sheets of glass to be laminated are placed on a formwork called a mold, essentially stacked on top of each other, heated, and heated. The bent shapes of the two glass sheets obtained in the thermal softening bending process are substantially the same, and the degassing treatment described above can be carried out relatively easily and completely.

The present invention is a method for bending a glass plate in which the entire glass plate placed on a mold is heated to a predetermined temperature, and then the bent portion of the glass plate is heated along the bending line where the glass plate is to be sharply bent. The glass plates are laminated and placed on a mold so that they can be bent into substantially the same shape, so that the glass plates having the shapes described above can be laminated together.

In the present invention, two glass plates are placed in a stacked state on a mold, and a local heating means is disposed close to the lower glass plate along the bending line to be sharply bent, and the other glass plate is placed in a stacked state on a mold. A layer of endothermic paint is formed on the surface of the upper glass plate along the bending line that is to be sharply bent, and the entire glass plate is heated to a predetermined temperature, and then local heating is performed using local heating means. As a result, compared to the conventional case where either the upper side or the lower side is bent using only the local heating means, the plate glass on the side remote from the local heating means (in the case of the present invention, the upper side) is bent. There is no insufficient heating,
Since the upper and lower glass plates can be bent at approximately the same temperature, the two glass plates can be bent into substantially the same shape.

In addition, in the present invention, since the local heating means is disposed on the lower side of the glass plate, there is no problem in loading and unloading the plate glass into the mold (if it is disposed on the upper side, loading and unloading the plate glass into the mold is difficult). In some cases, a device is required to avoid local heating means at a location that does not interfere with loading/unloading.)

The present invention will be explained below with reference to the drawings.

Figure 1 is a side view showing the state when the glass plate is placed in the mold, Figure 2 is a side view showing the state after bending, and Figure 3 is a perspective view of the glass plate. is a mold; 2 and 3 are upper and lower glass plates placed on the mold; 4 is a local heating means disposed along the bending line of the lower glass plate 3 at a predetermined distance from the glass plate; 5 is an endothermic paint layer formed along the bend line of the upper glass plate 2 on the surface of the glass plate slightly wider than the bend line, and is an endothermic paint layer (black ceramic paste) 5.
1m/m plate 2 glass with which is formed is on the top side, 2m/m plate glass 3 without heat absorbing paint layer
The layers were stacked with the bottom facing down, placed on the mold 1 of the desired shape, and heated in a bending furnace (not shown) until the entire body reached approximately 600°C. is approx.
The temperature reached 620℃, which is 20℃ higher.

In this state, the local heating heater 4 is turned on and heating of the area of the plate glass to be sharply bent is started.
When the temperature of the section reached 645° C., the wings 6 were activated and each of the two glass sheets could be sharply bent into substantially the same shape along the bend line. In this case, the glass plate temperature in the area where the endothermic paint layer was provided was only 1 to 2°C lower than the temperature in the area heated by the local heating heater, making it possible to make both temperatures almost equal.

When two sheets of glass that had been partially sharply bent as described in the above example were laminated using polyvinyl butyral as an interlayer film in a normal manufacturing process for laminated windshield glass for automobiles, deaeration failure or No problems such as interlayer peeling occurred.

As described above, according to the present invention, it is possible to easily produce bent glass having sharply bent portions with sufficient bending precision to allow lamination processing.

[Brief explanation of drawings]

FIG. 1 is a side view showing the state of the plate glass when it is placed in a mold, FIG. 2 is a side view showing the state after bending, and FIG. 3 is a perspective view of the plate glass. 1 ... Mold, 2, 3... Upper and lower glass plates placed on the mold, 4... Local heating means, 5... Endothermic paint layer, 6... Wing.

Claims (1)

[Claims] 1 In a sheet glass bending method in which the entire sheet glass stacked with two sheets placed in a mold is heated to a predetermined temperature, and then the sheet glass is locally heated along the bending line and bent at a sharp angle, the lower side of the one A local heating means is disposed at a predetermined distance from the lower glass plate along the bending line of the glass plate, and an endothermic paint layer is formed on the surface of the upper glass plate along the bending line of the other upper glass plate. A method for bending sheet glass characterized by local heating.