JPS6042176B2 - Glass plate forming method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a glass plate forming method for forming a front glass plate of a fluorescent display tube and the like.

Conventional glass plate forming technology involves heating the four peripheries of a glass plate while clamping and fixing them between upper and lower jigs, and extruding the central part of the glass plate using a rectangular core to form a nearly flat extruded part. is proposed.

One problem with this type of prior art is that the flatness of the extruded portion is not necessarily good because the softened glass sags excessively due to its own weight.

It is an object of the present invention to provide an improved glass plate forming method that allows a flat extrusion molded part to be obtained.

In order to achieve this object, the present invention is such that a rectangular core is formed so that four corners or two sides protrude, and a glass plate is extruded on the four protruding corners or two sides.
The following description will be made with reference to the accompanying drawings.

FIG. 1 shows a front glass plate 10 of a fluorescent display tube to which the present invention is applied, where 10A is an extruded part, that is, a display surface, and IOB is a flange corresponding to the four peripheries held down by a jig. Section 1OC is an exhaust pipe section.

It is desirable that the display surface IOA of such a windshield plate 10 be as flat as possible, and various methods have been devised to obtain flatness. As one of these methods, a technique has been proposed in which excessive drooping of the glass is suppressed by adjusting the pressure in the sealed space between the glass plate and the jig.
Windshield plate 10 of FIG. 1 having an exhaust pipe section IOC
In these cases, such technology cannot be adopted. This is because it is impossible to form a sealed space due to the existence of the exhaust pipe section IOC. The present invention provides a method that can be easily adopted even when manufacturing a front glass plate 10 having an exhaust pipe portion IOC, and the principle thereof is as shown in FIG. The four peripheries of the softened glass plate are pulled outward with a top and bottom jig, and the four protruding corners of the rectangular core are used to push down the four points A, -B, C, and D. It is.

In this way, since the four outer circumferences of the central part that should become the display surface are held down by the upper and lower jigs, the central part (A.B.
, C, and D) are pushed up and curved upward. However, this upward curvature can be offset by the natural drooping of the glass due to its own weight, that is, by the downward curvature, and in this way, an overall flat display surface can be obtained. Next, Figures 3a to 3
A preferred embodiment of the present invention will be described with reference to FIG.

First, in the step shown in FIG. 3a, the glass plate 20 having a portion to become the display surface 20A is placed on the lower jig 21, and the upper jig 22 is stacked on top of it, and the four peripheries 20B of the glass plate 20 are It is clamped and fixed with upper and lower jigs 22 and 21.

Then, the core 23 is placed on the glass plate 20 through the center hole of the upper jig 22. The core 23 has a concave central portion on the lower surface, and has four protruding corners on the lower surface, so that the four protruding corners press the corresponding four points on the glass plate 20. After this, in the step shown in FIG. 3a, the structure shown in FIG. 3a is heated in an electric furnace at an appropriate temperature, and the glass plate 20 is heated.
Soften. At the initial stage of molding, the glass plate 20 is pressed at four points, so that its central portion curves toward the central concave surface of the core 23. In the latter stage of molding, the softened central portion of the glass plate 20 naturally hangs down due to its own weight, forming a flat display surface 20A, as shown in FIG. 3c.
Therefore, if the structure shown in FIG. 3c is taken out of the furnace and allowed to cool naturally at the time shown in FIG. 3c when the flat display surface 20A is obtained, the desired windshield plate 20 with a flat display surface can be obtained. can. This type of windshield plate 20 is generally mass-produced in four pieces, and is automatically conveyed by a belt conveyor or the like, and the central part is turned into a flat display surface by softening, shaping, and its own weight of the glass plate 20. It is constructed through a thermoforming process in an electric furnace to make it 20A, and the natural cooling process outside the electric furnace.

In other words, the glass plate 20 is formed as a sample molded under various conditions such as the material, thermoforming temperature, thermoforming time, etc., and the central part is flattened to the optimum degree based on the sample. The display screen 20A can be constructed as follows. Further, the flatness of the central portion of the display surface 20A may be detected by a detector, such as a laser detector or an ultrasonic detector, and then subjected to natural cooling treatment.

As explained above, according to this embodiment, the four corners of the rectangular core 23 are made to protrude from the front, and the display part (center part) 20A of the glass plate 20 is pushed out by these four protruding corners. By doing so, the display portion 20A can be actively curved and the display portion 20A can be flattened by drooping due to the weight of the glass plate 20. Therefore, the jigs 21, 22 and the center of the simple structure that do not require a flat surface can be used. The glass plate 20 can be formed using the child 23.

Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment and can be implemented in various modified forms.

For example, in the above example, the glass plate was held down by the four corners of the core, but for products with a narrow extruded part (display surface), two sides along the length of the rectangular core may be made to protrude. However, the same effects as those described above can be obtained.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing a front glass plate of a fluorescent display tube to which the present invention is applied, FIG. 2 is a perspective view for explaining the invention in detail, and FIGS. 3a to 3c are FIG. 2 is a sectional view showing a process of forming a display tube windshield plate according to an embodiment of the present invention. 10, 20... Windshield plate, 10A, 2
0A...Display surface, 10B, 20B...
Flange part, 10C...Exhaust pipe part, 21...
...Lower jig, 22...Upper jig, 23... Core.

Claims (1)

[Claims] 1. Glass plate forming, which involves heating the four peripheries of the glass plate while clamping and fixing them with a pair of jigs, and extruding the central part of the glass plate using a rectangular core to form a substantially flat extruded part. A method for forming a glass plate, characterized in that the four corners or two sides of the rectangular core are made to protrude from the front, and the central part of the glass plate is pushed out using the four protruding corners or two sides.