JPH0139975B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a bend-strengthened glass sheet that can be bent sharply.

Recently, sharply bent tempered glass sheets have begun to be used for automobile rear windows and the like, and the required sharply bent bent tempered glass sheets are becoming increasingly diverse.

Generally, tempered glass having a curved surface is strengthened by heating and bending the glass into a desired shape using a bending die or by pressing, and then rapidly cooling the glass.
This heating heats the entire glass plate to a temperature near its softening point.
For example, it is carried out by heating to about 640-730°C. If heated too high above the softening point, undesirable deformation such as doubling will occur. However, if there is a part that requires sharp bending, the bending process cannot be performed satisfactorily unless the part is heated above its softening point and sufficiently softened. Therefore, in such cases, the entire glass plate is heated in a heating furnace to a temperature close to its softening point, and conductive printed wires, nichrome wires, etc. are printed or printed along the sharp bending lines of the glass plate. After installing or holding the heater wires at a constant distance from the bending line and applying a voltage to these heater wires to partially heat the vicinity of the bending line to a temperature above the softening point, Alternatively, bending is performed using a press.

However, the glass plate that has been bent is
Since the temperature near the sharp bending line and other parts are different, if this is rapidly cooled and strengthened, there is a risk of thermal cracking, and plane stress will be generated after cooling, reducing the quality of fracture. For example, during a destructive test, small pieces may be generated, which may not meet the crushing quality specified by JIS for tempered glass for automobiles. Furthermore, since the temperature near the sharp bending line is high even after bending, there is a problem that the curvature is unstable until the quenching and softening process.

An object of the present invention is to provide a bending tempered glass plate having a sharp bending process, even if the bending line to be sharply bent is partially heated above the softening point along the bending process, the cooling and strengthening after bending process is prevented. The bending tempered glass sheet has a stable curvature and does not deform during the bending process, generates less plane stress after cooling due to heating the part to a higher temperature than other parts, and does not deteriorate the crushing quality. We provide the manufacturing method.

In the method for manufacturing a bent tempered glass sheet according to the present invention, the bending process of the glass sheet is performed using a convex first press member and a plurality of elements that are divided by a line connecting a portion of small curvature and are hinged to each other. The precooling is performed by a pressing method using a concave second press member that can form a molding surface corresponding to the convex surface by regulating the movement position of the element. This method is characterized by blowing air toward the bending line of the glass plate to be bent from a plurality of nozzles provided along the hinge line inside the concave part of the press member 2. .

In a preferred embodiment of the method for producing a bent tempered glass sheet according to the present invention, when sharply bending, the heating temperature is set at a portion along the bending line to about 30° higher than other portions.
The temperature should be about 80°C higher.

FIGS. 1a and 1b show perspective views of an automobile rear window as an example of a sharply bent tempered glass sheet. Figure a is a hatchback type, and b
The figure is of the notebook type. For example, the glass plate 1 is 20 to 80R along the co-reflective curve 2.
It is bent with a certain degree of curvature. In order to manufacture this bent tempered glass plate by bending it using a press method, as shown in FIGS. The heater wire 4 is arranged along the curved line, and a portion thereof is heated to a higher temperature than the other portion along the curved line. The heating temperature of the entire glass plate 1 is a temperature near the softening point, e.g.
The heating temperature is 640 to 730°C, and the heating temperature for partially heating along the bending line is above the softening point and about 30 to 80°C higher than the general heating temperature, for example.
The temperature is preferably 670 to 810°C, more preferably 710 to 760°C.
These temperatures are selected appropriately depending on the type of glass, the degree of bending, the type of bending device, etc., and the key is to achieve the softening state necessary for each bending process, and to prevent doubling during and before and after the bending process. It is necessary to prevent changes from occurring. Also,
It is desirable that the overall heating temperature and the heating temperature at which the bent portion is heated to a high temperature are close to each other within a range that allows the bending to be performed at a desired curvature along a desired sharp bending line. It is particularly preferable that this temperature difference is generally within 50°C. The above example shows an example in which heater wires are arranged at predetermined intervals along the bending line of the glass plate to locally heat the bending line part, but the heater wire is brought into contact with the bending line of the glass plate. A method of printing a heater wire on a curved line of a glass plate and heating the printed heater wire locally can be similarly applied.

When sharply bending a glass plate, a pressing method is generally used. And if necessary, pressing means can be used for assistance. For example, when molding is performed using a press method, a suspended glass plate is inserted between first and second press members that have mutually complementary shapes and are opposed to each other. Press with a press member to form the desired shape. The molding surfaces of these first and second press members may each have a desired molding curved surface shape, or one of them may be a convex shape having a desired molding curved surface, and the other one may have a desired molding contour. It may be concave. In particular, when bending sharply using the press method, it is easy to get scratches, etc.
The first press member has a concave shape, and this concave press member is divided by a line connecting small curved parts to form a plurality of concave elements, and these elements are hinged to each other, and the movement position of the elements is regulated. A press mold that can form a concave surface in the contour portion corresponding to the convex surface of the second press member is often used. Therefore, an example will be described in which the bending process of the method of the present invention is performed using this press die.

FIG. 3 is a partial sectional view schematically showing a state in which a glass plate is sandwiched between the press molds as described above. A glass plate 1 is placed between a first press member 5 having a convex shape and a second press member having concave portions 6A and 6B of a press mold. The concave molds 6A and 6B of the second press member are connected by a hinge 7. Convex type 5 by air cylinder
After advancing the concave mold 6A of the main parts of the first press member 5 and the second press member to sandwich and press the glass plate 1, the concave mold 6B is moved by the air cinder 8 to form the concave mold 6A and the concave mold 6B. The surface of one press member 5 is made to correspond to the surface of the second press member 5 having a convex shape. Therefore, the convex second press member 5 and the second
The glass plate 1 is also bent by the concave die 6B of the press member, and the required bending process is performed. Concave 6
It goes without saying that the portion of the glass plate 1 facing the hinge connection line A and 6B is partially heated to a high temperature. Bending processing using this type of press die is
Since this has been commonly practiced in the past, detailed explanation will be omitted.

In one embodiment of the apparatus for carrying out the method of the present invention, an air blowing pipe 9 is provided along the hinge line in a hollow part inside the concave shape of the second press member as shown in FIG. The pipe 9 is provided with a plurality of nozzles that blow air toward the bent line of the glass plate 1 where the glass plate 1 is to be bent sharply. At the same time as the glass plate 1 is finished being pressed by this press die, or as soon as possible after that, air is blown from a nozzle to partially heat the heated part.
Pre-cool it to approximately the same temperature as other parts. Generally, a few seconds is sufficient, and it is necessary to carry out the process in such a short time.

Alternatively, a portion of the convex surface of the first press mold corresponding to the bending line of the glass sheet may be hollowed out, and an air blowing pipe may be provided in that portion to pre-cool the sharply bent portion of the glass sheet. A small hole may be made in a portion of the molding surface corresponding to the bending line of the glass plate, and air may be blown out through this hole. Note that the above example is an example in which an air blowing pipe is provided inside the concave portion of the second press member, but air for pre-cooling the curved portion of the glass sheet is provided between the press bending device and the air cooling strengthening device. It is also possible to immediately pre-cool the curved portion of the sharply bent glass plate using the air blowing pipe after the blowing pipe is provided and the bending process is performed. Alternatively, after pressing, an air blowing pipe can be moved to the bending line of the glass plate in the press to pre-cool the bending line within the press.

After the glass plate is sharply bent, it is easy to design the device to pre-cool the curved line from one side of the glass plate, but it can also be done from both sides of the glass plate. .

Next, it is transported to a cooling facility and strengthened by air cooling, as in the general air cooling reinforcement process.

As described above, when bending and strengthening a glass plate by sharply bending it by the method of the present invention, the bending-strengthened glass plate can be made to have a stable curvature based on the design, and the sharply bent portion can be partially bent to a high degree. Even though it is heated to a high temperature, the bending line part is pre-cooled to equalize the temperature of the entire glass plate, which reduces the plane stress caused by temperature unevenness that occurs in the bending line part that has been heated to a high temperature. It is possible to obtain a high quality bent tempered glass sheet without deteriorating the crushing quality.

Note that the pre-cooling of the bent line portion of the glass plate of the present invention after bending is to stabilize the curvature of the sharply bent bend line portion and to prevent undesirable deformation from occurring. It is also applicable to a method of bending a glass plate that does not require any processing.

[Brief explanation of drawings]

FIGS. 1a and b are perspective views of an automobile rear window, which is an example of a glass plate manufactured by the method of the present invention, and FIGS. A schematic diagram showing a situation in which partial heating is performed along a line, and FIG. 3 is a partial schematic diagram of a press bending device. 1...Glass plate, 2...Bending line, 3...Hanging tool,
4...Heater wire, 5...Convex type, 6A, 6B...
Concave type, 7...hinge, 8...air cylinder, 9...
...Air blow pipe.

Claims (1)

[Claims] 1. Bending of a glass plate is performed using a convex first press member and a plurality of elements that are divided by a line that connects a portion with a small curvature and are hinged to each other,
The precooling is performed by a pressing method using a concave second press member that can form a molding surface corresponding to the convex surface by regulating the movement position of the element, and the precooling is performed by Bending of a tempered glass sheet characterized in that the bending process is performed by blowing air toward the bending line of the glass sheet from a plurality of nozzles provided along the hinge line inside the concave part of the press member. Manufacturing method.