JP2000256023A - Curvilinear forming mold for sheet material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a curvilinear forming mold of sheet material which facilitates mold management and is capable of stably curvilinearly forming glass sheets for a long period and the curvilinear forming mold for sheet material which is capable of shortening the working time for curvilinear forming by lowering a heat capacity over the entire part. SOLUTION: A mold member 3 is formed with many suction holes 3b at a cavity 9 point formed flush with the curved surface of the curvilinear sheet material formed atop the same and has a mounting hole 5 communicating with the internal space part on the rear surface. A base member may be placed on a firing base and has a part to be mounted to which the mold member is mounted at its front surface. The base member also has through-holes connectable to a vacuum suction device at the points to be mounted. The mold member and the base member consist of petalite ceramic material having heat resistance and impact resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to, for example, a flat glass plate having a curved surface having a predetermined radius of curvature.
This also includes a case where an aspherical gradually changing curved surface whose curvature radius gradually changes is integrally provided on a curved surface having a partially different radius of curvature or a curved surface having a constant radius of curvature. The present invention relates to a curved mold for a plate material used in forming (1).

[0002]

For example, a rear mirror of a vehicle, an interior mirror, and the like use a mirror in which a flat glass plate is formed on a convex curved surface in order to enlarge the rear field of view. In order to form a flat glass plate into a desired curvature radius or an aspherical convex curved surface, use a diatomaceous earth curved mold having a cavity having a desired radius of curvature formed on the upper surface, and use the curved mold. In a state where a flat glass plate is set on the glass plate, the glass plate is curved by heating the glass plate to a softening temperature and vacuum-sucking the glass plate so that the glass plate matches the cavity surface.

[0003] The above-mentioned diatomaceous earth bending mold has a relatively low heat capacity and can be heated to the softening temperature of the glass plate in a short time. However, since the material itself is brittle, the edges and cavities are easily formed. It was easy to lose. For this reason, when a glass sheet is bent using this type of bending die, the cavity surface must be corrected to a desired bending radius for each bending operation, and the forming workability is extremely poor. Was.

[0004] Further, since a curved mold made of diatomaceous earth has a poor surface roughness, it is necessary to polish and smooth the glass plate after molding, so that the number of manufacturing steps is increased and the cost is increased. I was

Further, since a diatomaceous earth-made curved mold has a high hygroscopicity, when the mold is heated and used again after being left in the air, the curved glass is released due to the water vapor pressure released from the mold due to the heating. There was a tendency for the plate surface to have irregularities and to be defective. This drawback can be solved by heating the curved mold to release the absorbed moisture prior to the curve molding operation, but this increases the number of working steps and makes it difficult to handle the heated curved mold. , Work efficiency was poor.

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned conventional drawbacks. It is an object of the present invention to easily form a glass plate for a long time by easily managing a mold. An object of the present invention is to provide a curved mold for a plate material that can be formed.

Another object of the present invention is to provide a plate-shaped bending mold capable of reducing the overall heat capacity and shortening the bending-forming operation time.

[0008]

SUMMARY OF THE INVENTION Therefore, the present invention is directed to a method of forming a plurality of suction holes in a cavity formed in conformity with a curved surface of a curved plate formed on an upper surface and an inner space in a lower surface. A mold member having a mounting portion communicating with the portion and a base member which can be placed on the baking table, has a mounting portion on the upper surface, and has a through hole connectable to a vacuum suction device at the mounting portion portion. It is made of a petalite porcelain material having heat resistance and impact resistance.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is an exploded perspective view of a curved mold for a plate material,
FIG. 2 is a longitudinal sectional view corresponding to the line II-II in FIG.

The curved forming die 1 for a plate material comprises a mold member 3 and a mold mount 5. The mold member 3 and the mold mount 5 are made of petalite, kaolin, lithium carbonate, clay, or the like, and have a shape shown in the figure. About 800 ° C after each molding
The chemical composition fired in the above is SiO ₂ , Al ₂ O ₃ , Fe ₂
It is made of a Lithia petalite porcelain made of O ₃ , K ₂ O, Na ₂ O or the like.

The mold member 3 has a required thickness t, is formed in a box shape having a hollow portion 4 therein, and a cavity 9 is formed on the upper surface plate 3a so as to match the curved surface of the curved glass plate 7 to be formed. Have been. Also, the upper surface plate 3a corresponding to the cavity 9
A large number of suction holes 3b each having a small diameter are formed in a matrix at predetermined intervals in the row direction and the column direction. A cylindrical portion 3 c as a mounting portion communicating with the inside is integrally formed on the lower surface of the mold member 3, and the cylindrical portion 3 c is inserted into the mold mounting base 5.

Although the thickness t of the mold member 3 is suitably small in order to enable heating in a short time, a certain thickness is required to prevent breakage due to suction pressure.

The mold mounting base 5 is a flat rectangle having a size substantially coincident with the shape of the mold member 3, and a mounting portion 13 to be fitted into the cylindrical portion 3c is integrally formed at the center of the upper surface. A through hole 15 is formed in the mold mounting base 5 corresponding to the center of the mounted portion 13. The through holes 15 are placed on a firing table 17 which is moved into a heating furnace (not shown).
Is set on the baking table 17 and inserted into a suction port 18 connected to a vacuum suction device (not shown).

The capacity of the hollow portion 4 in the mold mounting table 3 buffers the negative pressure when vacuum suction is performed through the through hole 15 so as to equalize the suction pressure through the suction holes 3b. When the suction pressure is high, it is necessary to increase the capacity. Further, although the figure shows three through holes 15, a single through hole may be used.

Next, a description will be given of the operation of bending a glass sheet using the above-described plate material bending mold 1. FIG. 3 and FIG. 4 are longitudinal sectional views showing a state in which the glass sheet is curved and formed.

The mold mounting table 5 is set on the firing table 17 of the heating furnace, and the through holes 15 are connected to a vacuum suction device. After the mold member 3 is mounted on the mold mounting base 5 so that the mounting portion 13 is inserted into the cylindrical portion 3c, a flat glass plate 19 is placed on the upper surface plate 3a corresponding to the cavity 9. set.

In the above state, the vacuum suction device is driven to move the firing table 17 into the heating furnace while sucking and holding the glass plate 19 on the upper surface of the upper plate 3a of the mold member 3. The stage 17 is heated to about 700 ° C., which is the softening temperature of the glass.
Heat to

The glass plate 19 softened by the heating is pressed against the mold surface of the cavity 9 by the negative pressure used through the suction hole 3b to be formed into a curved glass plate 7 which matches the curved surface of the cavity 9. .

After the above-mentioned forming, the firing table 17 is carried out of the heating furnace, and the curved glass plate 7 which has been formed into a curved shape is gradually cooled by air cooling to complete the forming operation.

Since the above-mentioned curved mold 1 has higher hardness than the conventional diatomaceous earth curved mold, the number of molds that can be formed by the conventional curved mold is about 5,000 times, while
It could be used up to 00 times. At that time, there was little breakage and wear during handling, and the work of correcting the curved surface of the cavity 9 could be reduced. Furthermore, since the curved mold 1 has a lower hygroscopic property than the conventional diatomaceous earth mold, it is not necessary to heat the curved mold 1 itself to discharge moisture prior to heat molding, thereby reducing the number of molding operation steps. We were able to.

When the plate-shaped curved mold 1 is heated at about 700 ° C., no gas is generated, and the glass plate 19 can be formed into a curved surface having a predetermined curvature without irregularities and excellent in smoothness. did it.

When the glass plate 19 is formed into a curved glass plate 7 by bending, it is required that the entire temperature of the plate-shaped bending mold 1 be raised uniformly. In order to solve the drawback of the conventional diatomaceous earth curved mold, that is, the easiness of chipping, the mold member 3 is used.
It is also known to use fused silica, ceramics, etc., but these materials have a heat capacity of about 500 cal / ° C.
Although it was relatively high as described above and it took time to heat the mold itself, in the curved molding die 1 of the plate material of the present invention, the mold member 3 and the mold mount 5 are each made of a petalite porcelain material, and have a relatively large heat capacity. Since the temperature is low, the entire curved mold 1 of the plate material can be heated to the softening temperature of the glass in a short time.

[0023]

According to the present invention, therefore, the mold can be easily controlled, and the glass sheet can be stably formed into a curved shape over a long period of time. Further, the present invention can reduce the heat capacity as a whole and shorten the bending molding operation time. In the above description, a glass plate is used as the plate material to be curved, but a synthetic resin plate having a metal reflective thin film formed on one surface may be used.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a curved mold for a plate material.

FIG. 2 is a longitudinal sectional view corresponding to the line II-II in FIG.

FIG. 3 is a longitudinal sectional view showing a state in which a glass sheet is curved and formed.

FIG. 4 is a longitudinal sectional view showing a state in which a glass sheet is curved and formed;

[Explanation of symbols]

1-curved mold, 3-mold member, 3a-top plate, 3b-suction hole, 5-mounting stand, 7-curved glass, 9-cavity

Claims (3)

[Claims] 1. A mold member having a plurality of suction holes formed in a cavity formed in conformity with a curved surface of a curved plate formed on an upper surface, and having a mounting portion communicating with an internal space on a lower surface. A petalite porcelain that can be placed on a firing table, has a mounting portion on the upper surface, and has a through hole at the mounting portion that can be connected to a vacuum suction device, has heat resistance and impact resistance. Curved mold for plate material made of material. 2. A curved mold for a plate member according to claim 1, wherein the mold member has a box-like shape having a large-capacity hollow portion therein. 3. The curved mold according to claim 1, wherein the petalite porcelain material is a plate material obtained by firing a raw material such as petalite, spodumene, lithium carbonate and clay.