JPS582169B2 - Method for manufacturing bent glass - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing bent glass, and particularly to a method for manufacturing the above-mentioned glass intended to improve the strength around the glass.

The general method of bending laminated glass is to stack multiple sheets of flat glass that have been cut into a predetermined shape and polished, with fine inorganic powder sprinkled between the glass sheets to prevent fusion, and this glass stack is supported only around the edges of the glass. Place the ribbon in a mold and heat the glass at an appropriate speed to its softening point, bend the stack to the shape of the mold, and then gradually cool the glass to prevent distortion from remaining inside the glass. The laminated glass is bent after cooling to room temperature.

Glass made in this way has lower strength at the periphery of the glass than at parts other than the periphery.

Therefore, laminated glass made in this way can be used in automobiles,
Or, if it is used in a building, it may cause unexpected damage to the weaker surrounding areas.

When a glass plate is rapidly cooled, residual stress is generated around it, but since the glass surface has a certain area, it is rapidly cooled non-uniformly.

Further, during rapid cooling, only the outermost surface of the stack is cooled quickly, which causes warping of the glass and deformation of the glass that has been bent into a predetermined shape.

This also causes mutual deformation of the paired glasses to be laminated, which is undesirable in terms of manufacturing the laminated glass.

In addition, if a continuous furnace is used to heat and slowly cool the glass, a considerable distance is required for the heating area of the furnace in order to increase the feeding speed of the mold and cool the glass to near room temperature. They are forced to bear the burden of capital investment, which deviates from the economic effect.

As described above, the present invention was developed using the concept of generating residual stress around the glass by rapidly cooling the glass.

Therefore, in contrast to the conventional method of cooling the glass gradually to avoid temperature differences in order to avoid leaving residual strain on the glass,
The purpose is to cool the periphery of the glass faster than the rest of the glass.

In the present invention, a pair or multiple pairs of flat glass stacked on top of each other are held horizontally in a mold and bent while being heated in a heating process.
A method of manufacturing bent glass by subsequently slowly cooling the glass to room temperature in an annealing process, the glass being cooled at least in its periphery faster than other parts before passing through the annealing midpoint in the annealing process. The gist of this is to cover at least the main surface of the flat glass except for the periphery thereof with a heat insulating material or a heat insulating material.

The positions where the glass is covered with heat insulating material, etc. are the upper and lower surfaces of the stacking frame body, and before placing the stacked glass body to be heated on the mold, the position where the glass is covered with the heat insulating material, etc. A heat insulating material or heat retaining material with a shorter outer circumference is placed on the mold, and a glass stack is placed on top of it so that its end face is exposed from the heat insulating material, etc., or so that its surrounding area overhangs the heat insulating material, etc. Then, heat the glass to bend it, and then place another heat insulating material of the same shape before passing the strain point, or heat the glass when using a heat-permeable heat insulating material such as glass cloth. In practice, the present invention can be carried out by placing a heat insulating material before bending.

Examples of the heat insulating material or heat retaining material include glass cloth, heat-resistant fiber mat, asbestos, diatomaceous earth block, etc., and these are heated to the same temperature as the glass plate.

Furthermore, a heater may be inserted in the center of the heat insulating material in order to create a temperature difference with the surrounding areas.

The heat insulating material may be placed in contact with the glass, or may be placed at a slight distance from the glass, as long as it does not damage the surface of the glass.

Furthermore, if stress is not generated uniformly in the surrounding area due to the shape of the glass, the shape of the heat insulating material can be changed and the position relative to the glass can be appropriately adjusted.

The above-mentioned heat insulating material is selected from those having a heat resistance of about 650° C., taking into consideration the softening point of glass and the like.

As described above, the lower insulating material 2 is laid on the mold 1, the glass plate stack 3 is placed on top of it so that the periphery protrudes from the insulating material, and the glass plate is heated in a heating furnace (not shown) to form the shape of the mold. transform into.

During slow cooling, a heat insulating material 4 having substantially the same shape as the heat insulating material 2 is used to cover the glass except for the periphery 5, and the glass is slowly cooled.

Due to the gradual cooling of the surrounding area, the peripheral area is cooled faster than other areas such as the central area, so a temperature difference is created between the two areas, and stress proportional to the temperature difference is not generated in the surrounding area, which reduces the peripheral strength. Improvements are made.

Reference example 1 A set of two glass plates with a thickness of 2.0 mm x length of 1300 mm x 500 mm was placed on a mold, heated to 610°C, bent, and then cooled at a cooling rate of approximately 4 to 5°C/min. Slow cooling was performed.

The residual stress generated around the obtained glass plate was 25 kg/c.
It was m2.

Reference Example 2 Five sets of the same glass as in Reference Example 1 were stacked and placed in a mold, heated under the same conditions as in Reference Example 1, and cooled under the same conditions.

The residual stress generated around the obtained glass plate was 50 kg/c.
It was m2.

Example 1 Two glass plates with a thickness of 2.0 mm x length of 1300 mm x width of 500 mm were placed on a mold as a set, and the upper and lower surfaces of the glass plates were covered with glass cloth, leaving a 5 mm peripheral area of the glass plates. After heating to 610° C. and bending, slow cooling was performed at the same cooling rate as in Reference Example 1.

As a result, the residual stress generated around the glass plate was 75 to 10
It was 0 kg/cm2.

Example 2 Five sets of two glass plates with a thickness of 2.0 mm x length of 1300 mm x width of 500 mm were placed on a mold, and the upper and lower surfaces of the glass plates were covered with glass cloth, leaving a 5 mm peripheral area of the glass plates. After covering it with water and heating it to 610° C. and bending it, slow cooling was performed at almost the same cooling rate as in Reference Example 1.

As a result, the residual stress generated around the glass plate was 150~2
00 kg/cm2.

[Brief explanation of drawings]

FIG. 1 is a side view of an example for carrying out the method of the present invention, and FIG. 2 is a plan view of the same. 1...Mold, 2, 4...Insulating material, 3...Glass stack.

Claims (1)

[Claims] 1. A method for manufacturing bent glass, in which a pair or multiple pairs of flat glasses stacked on top of each other are held horizontally in a mold, heated and bent in a heating step, and then slowly cooled to room temperature in an annealing step, Before the glass passes through the strain point in the slow cooling process, a heat insulating material or a heat insulating material is placed on at least the main surface of the uppermost flat glass except for the periphery so that the periphery of the glass is cooled faster than other parts. A method for manufacturing bent glass with improved peripheral strength, characterized by covering.