JPH0217488B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for simultaneously molding a plurality of thin and highly curved glass products such as funnels for cathode ray tubes (CRTs).

(Prior Art) Methods for manufacturing glass products such as funnels for cathode ray tubes can be roughly divided into two methods: a method of press-forming molten glass and a method of vacuum-forming a glass plate.

The method of molding from molten glass involves loading the molten glass into the molding section of a molding die, and then pressing the molten glass with a molding plunger to shape it along the molding surface. The method of molding from a plate involves sandwiching a glass plate between upper and lower molds made of carbon with excellent wettability, heating the glass plate in this state, and then molding the glass through suction holes opened on the molding surface of the mold. It is designed to evacuate the board.

(Problems to be solved by the invention) Regarding the method of press-molding molten glass,
A glass melting furnace, a molten glass take-out device, a press device, etc. are required, making the entire device large-scale.Also, when molten glass is press-molded between molds, the molten glass is cooled and solidified by the molds. There is a problem that thin-walled glass products cannot be formed. On the other hand, when using a carbon mold, the glass plate can be molded while the mold is heated to a high temperature, so thin glass products can be molded.
Since heat forming and slow cooling are performed with the glass plate held between the molds, there is a problem in that it takes one cycle from setting the glass plate to completing the molding.

In addition, in any of the above methods, since only one glass product is molded using one mold, there is a problem in terms of production efficiency.

(Means for Solving the Problems) In order to solve the above problems, the present invention aims to mold a glass plate into an approximate shape by pushing a part of the glass plate heated by a plug halfway into a molding part formed in a mold. After that, the glass plate is vacuum-formed, which shortens the time from setting the glass plate to completing the molding.Furthermore, the mold has multiple molding parts, and multiple glass products can be molded at the same time. Aimed to improve production efficiency.

(Example) Examples of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a diagram showing a schematic configuration of a molding apparatus used for carrying out the method of the present invention, in which a mold 1, a heater 2, and a press mold 3 are arranged in a heating furnace of the molding apparatus.

The mold 1 is made of a material with excellent wettability with glass, such as amorphous carbon, graphite, or boron nitride, and has a plurality of molding parts 4 in the shape of a funnel opening upward. is,
At the bottom of each molded part 4... there are suction holes 5 for vacuuming.
... are bored, and these suction holes 5 ... are connected to a vacuum pump (not shown). Here, the dimensions of the molded part 4 are, for example, the upper end opening is 10 mm x 12 mm.
mm, and the depth is 10 mm. In addition, when molding glass products with a thickness of 1 mm or less, the spacing between adjacent molding parts 4 should be such that interference between adjacent molding parts does not adversely affect the thickness distribution of the glass product. In order to do this, it is preferable to set the interval to 3 mm or more.

Further, the heater 2 is connected to the mold 1 in the heating furnace.
The press mold 3 can be moved up and down to the upper position, and the press mold 3 can be raised and lowered relative to the mold 1. Each molding part 4 of the mold 1 is provided on the lower surface of the press mold 3.
Plug 6... corresponding to... is attached.
The plug 6 has a shape substantially similar to the inner surface of the molded portion 4, and is preferably made of a material with good wettability such as amorphous carbon, graphite, or boron nitride.

A molding method using the molding apparatus as described above will be explained based on FIGS. 2 to 5.

First, as shown in FIG. 2, a glass plate G preheated to about 500° C. is placed on a mold 1. In this case, the mold 1 may be placed outside the heating furnace or may be fixed within the heating furnace. Next, as shown in FIG. 3, a heater 2 is placed on the mold 1 in a heating furnace.
and heat the glass plate G at a forming temperature (temperature close to the softening point), for example, about 800°C. For heating, when the mold 1 is made of amorphous carbon or graphite, the molding part 4 is filled with an inert gas such as nitrogen gas using the suction holes 5, and the mold is heated. It is preferable to prevent deterioration of 1.

Then, the heater 2 is moved back from above the mold 1, and the press mold 3, which was located above the mold 1, is lowered, and as shown in FIG. , the glass plate G is pushed into the molding part 4 of the mold 1. In this case, the plug 6 is maintained at a temperature of 300 to 500°C. The penetration depth of the plug 6 into the molded part 4 is such that the lower end of the plug 6 is 50% of the depth of the molded part 4.
The range is the 80% position. This is because if the penetration depth of the plug 6 is less than 50%, the thickness of the glass molded product will be uneven during subsequent vacuum forming.
%, the glass plate G pushed in by the plug 6 comes into contact with the inner surface of the forming part 4 and is rejected, causing local deformation of the glass plate during subsequent vacuum forming, resulting in a uniform thickness. This is because it is not possible to obtain a glass molded product with That is, if the pushing depth of the plug 6 is set to 50 to 80%, as shown in FIG. It is pushed into the forming part 4 and has a shape that is extremely suitable for subsequent vacuum forming.

Next, as shown in FIG. 5, the glass plate G pushed into the molding part 4 is evacuated through the suction hole 5 formed at the bottom of the molding part 4, and the glass plate G is tightly attached to the inner surface of the molding part 4. At least complete the molding. At this time, the area around the opening of the molded product is cut with a cutting die,
It may also be separated into individual glass molded products. Further, when performing vacuum forming, if the glass plate G is lower than the forming temperature, vacuum forming is performed after heating it again with the heater 2.

Then, the glass molded product is cooled while being placed in the molding part 4 of the mold 1, and when the temperature of the glass molded product is cooled to a temperature at which it does not deform, for example, 500°C or less,
The glass molded product is taken out from the molding section 4 and slowly cooled.

(Effects of the Invention) As explained above, according to the present invention, when forming a glass plate, at the beginning of the forming process, press forming is performed to obtain the approximate shape of the desired glass product, and then vacuum forming is performed. The time required for press molding can be greatly reduced, and since the glass plate does not come into contact with the molding surface during press molding, the glass plate is not locally cooled by the molding surface, resulting in uniform cooling. Can be molded into thick glass products. Therefore, it is possible to obtain glass products with a thickness of 1 mm or less, which was impossible using conventional press molding methods.

Further, according to the present invention, a plurality of glass products can be simultaneously formed from a single glass plate, which is also advantageous in terms of production efficiency.

[Brief explanation of drawings]

Figure 1 is a schematic diagram of the molding apparatus used to carry out the method of the present invention, Figure 2 is a sectional view of the glass plate placed on the mold, and Figure 3 is the glass plate being heated. FIG. 4 is a cross-sectional view showing a glass plate being press-molded, and FIG. 5 is a cross-sectional view showing a glass plate being vacuum-formed. In the drawings, 1 is a mold, 2 is a heater, 3 is a press mold, 4 is a molding part, 5 is a suction hole, 6 is a plug, and G is a glass plate.

Claims (1)

[Claims] 1. A glass plate is placed on a mold having a plurality of molding parts opening upward, and after heating this glass plate to near its softening point, the glass plate is placed above the mold and each molding part is opened. A press mold having a plug corresponding to the mold is relatively lowered, and as a result of this lowering, the glass plate is pushed halfway into the molding part by the plug of the press mold, and then the glass plate is pushed through the suction hole opened at the bottom of the molding part. A method for forming glass products characterized by applying a vacuum. 2 The press die has a plug tip that is at the depth of the molding part.
A method for forming a glass product according to claim 1, characterized in that the glass product is lowered to a position where the glass material penetrates from 50% to 80%. 3. A space between adjacent molding parts among the molding parts is 3 mm or more, and a thickness of the thinnest part of the glass product to be molded is 1 mm or less. A method of forming glass products.