JPH046118A - Bending mold for glass sheet and forming method by bending - Google Patents

Abstract

PURPOSE:To improve deep bendability of a glass sheet by heating the glass sheet to its glass softening temp. and forming the sheet into a shape conforming to a split type bending mold having a movable split mold and a fixed split mold by gravity bending. CONSTITUTION:A glass sheet 11 is placed on a bending mold 1, the mold 1 is developed by the rigidity of the sheet 11 to make the material 4 connecting counterweights taut, and the load of the main counterweight 2 plus the auxiliary counterweight 3 is exerted on the movable split mold 1a. The sheet 11 is sagged by gravity on heating, and the forming surface of the movable split mold 1a is then turned by gravity and the load of the counterweights 2 and 3 in such a direction as to communicate with the forming surface of the fixed split mold 1b. Consequently, the counterweights 2 and 3 are also turned and supported by a stopper 5. The connecting material 4 is loosened thereafter, only the load of the counterweight 2 is exerted on the movable split mold 1a, the movable split mold is turned until the forming surface of the movable split mold communicates with that of the fixed split, and the bending is finished.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method and an apparatus for bending a glass plate in a heating furnace, and in particular, to a method and an apparatus for bending a glass plate in a heating furnace. This invention relates to a method for bending a glass plate and an improvement in a bending mold used therein.

[Prior Art] In the conventional method of bending a glass plate, a bending die corresponding to the bending surface of the glass plate is constructed, and the bending die is placed in a heating furnace with the glass plate placed on the bending die. A known method is to heat the glass plate to its glass softening temperature and bend the glass plate under its own weight along the bending surface of the bending die as the glass plate softens. .

In such a method, if it is necessary to deep bend the side part of the glass plate, a ring-shaped fixed split mold having a bending surface corresponding to the intermediate curved part of the glass plate and a side part of the glass plate are used. It has a bending surface that corresponds to the deep bending part of the part,
The bending die is constituted by a ring-shaped movable split mold that is provided on both sides or one side of the fixed split mold so as to be movable in a direction connected to the fixed split mold under its own weight and a counterweight load, and the movable split mold is After stacking the flat glass plates on the bending mold in the unfolded state, the glass plates are carried into a heating furnace and heated, and as the glass plates soften, a counter load is applied to the movable split mold. A self-weight bending method has already been provided in which the glass is moved in a direction connected to a fixed split mold, and the side portions of both glasses are deeply bent by a movable split mold.

FIG. 3 shows an example of a split type bending die for bending a glass plate under its own weight. The mortar mold is placed on a carriage (not shown) of a conveyance means, and is a ring-shaped fixed split mold having a bending surface corresponding to the central curved part excluding both sides of the glass plate 11 which is deep bent. 1b, and has a bending surface that is movably provided on both sides of the fixed split mold ib and corresponds to the deep bending part of the glass plate 11, and this bending surface is connected to the bending surface of the fixed split mold 1b in the set position. It is composed of a ring-shaped movable split mold 1a that is continuous with the mold. The fixed split mold 1b is fixed on the trolley via a support, while the movable split mold 1a
is swingably supported by the fixed split mold 1b via a hinge 10.

Further, a counterweight 9 is attached to the support portion of the movable split mold 1a via a moment arm so that the movable split mold 1a is urged toward the set position side where it is connected to the fixed split mold 1b. In Fig. 3, (a) shows the flat laminated blank glass placed on the bending die before the glass plate is heated, and Fig. 3 (b) shows the glass plate after the bending process. This shows that. In the state shown in FIG. 3(a), the glass plate 11 hangs down due to its own weight, and by applying particular weight to the hinge 10 of the bending die l that the glass plate contacts, the movable split mold 1a is moved to a position where it is connected to the fixed split mold ib. move it. The design of the movable split mold may be changed as appropriate as long as it moves in a direction connected to the fixed split mold due to its own weight and counterweight and stops at a set position connected to the fixed split mold.

[Problems to be Solved by the Invention] However, in such a conventional glass plate bending method, when deep bending the side part of the glass plate, a movable split mold that is displaced by a counterweight and its own weight is used. The sides of the pixel plate glass are now forced to be bent, but in recent years there has been a demand for deeper bending of the sides of the glass plate than ever before, and in such cases, Although the shape of the periphery of the deep bending part of the glass plate can be formed into a shape that follows the movable split mold, except for the periphery of the deep bending part of the pixel plate glass (for the surface shape of the curved part, the central part of the glass plate bulges too quickly). In many cases, the sides are bowed toward the center, and the degree of deformation of the softened glass sheet cannot be followed to create the desired curvature surface, resulting in insufficient shaping of the deep bent portion of the glass sheet. In addition, since the bending die for deep bending has a deep arc, the glass does not come into contact with the hinge part at the beginning of bending.Therefore, when the glass plate hangs down, the hinge part is subjected to a load. First, because the movable split mold does not move sufficiently, the glass plate may not be bent properly, the glass plate may slip strongly on the die, causing reflection distortion, or in severe cases, the plate may slip. This caused the glass plate to even come off from the mortar mold.

On the other hand, if the counterweight load is increased, the above-mentioned difficulties at the initial stage of bending can be avoided, but this time,
After the glass plate has sufficiently softened, the movable split mold moves too quickly, which is also undesirable.

In addition, as a method for accurately forming the surface shape, it is possible to use a pressing method in combination, but there are problems in that the process becomes complicated and pressing marks are likely to be formed.

[Means for Solving the Problems] The present invention has been made to solve the above-mentioned problems, and it forms a predetermined shape by placing a glass plate thereon, heating it, and letting the glass plate hang under its own weight. A bending die used in bending, which includes a fixed split die having a bending surface corresponding to an intermediate curved portion of a predetermined shape, and a bending die having a bending surface corresponding to a side portion of the predetermined shape. The bending surface of the movable split mold has a movable split mold whose surface is rotatable around a rotation axis in a direction continuous with the bending surface of the fixed split mold on both sides or one side of the fixed split mold. To provide a bending die in which the load of a counterweight that applies a force so that it is continuous with the bending surface of a fixed split die changes in multiple stages during bending, and a method for bending a glass plate using the same. It is something.

In such technical means, the configuration of the heating and bending furnace used to bend and form the glass plate includes at least a heating and bending process stage that heats the glass plate to be formed to the softening temperature of the glass. As long as it has, the design may be changed as appropriate. In this case,
From the viewpoint of maintaining good bending formability, it is recommended to locally heat the side part of the glass plate to be deep bent to a higher temperature than other parts in the heating bending processing stage. preferable.

In addition, as the means for conveying the glass plate, as long as it is possible to convey the bending mold in the heating and bending furnace, a cart may be moved along a predetermined circulation path or forward and backward path, The design may be changed as appropriate, such as by using a continuous conveyor made of heat-resistant conveyor rolls, conveyor belts, etc.

FIGS. 1(a) and 1(b) are side views showing preferred embodiments of the bending mold used in the present invention. Moreover, FIG. 2 is an enlarged perspective view showing the structure of the mortar-shaped counterweight of the present invention. In this bending mold, movable split mold 1
A main counterweight 2 is fixed and attached to the movable split mold 1a so that the movable split mold 1a is biased in the direction in which the molding surfaces of the fixed split mold 1a and the molding surfaces of the fixed split mold 1b are aligned, and the load of the main counterweight 2 is An auxiliary counterweight 3 for adjustment is attached to the fixed split mold 1a via a connecting member 4 that can be tensioned and relaxed so as to be rotatable at a portion 6. Further, the auxiliary counterweight 3 is supported by a stopper 5 fixed to the fixed split mold ib while moving so that the molding surfaces of the movable split mold 1a and the fixed split mold 1b are connected to each other.

By adopting this configuration for the mortar mold, the load of the counterweight that applies force so that the bending surface of the movable split mold is connected to the bending surface of the fixed split mold can be changed in two stages during bending. become.

This effect will be explained. As shown in FIG. 1(a), when the glass plate 11 is placed on the mortar mold 1, the glass plate 11
Due to the rigidity of , the mortar mold 1 expands, the connecting member 4 connecting the counterweights is under tension, and the movable split mold 1a receives a load equal to the load of the main counterweight 2 plus the load of the auxiliary counterweight 3. is added. As it is heated, the glass plate 11 gradually hangs down due to its own weight, and then the movable split mold 1a is rotated by its own weight and the load of the counterweights 2 and 3 in a direction in which its molding surface is connected to the molding surface of the fixed split mold lb. . Along with this rotation, the main counterweight 2 and the auxiliary counterweight 3 also rotate, but the auxiliary counterweight 3 is supported by the stopper 5 during the rotation. After that, the connecting member 4 is relaxed, and only the load of the main counterweight 2 is applied to the movable split mold 1a, and the movable split mold is moved until the molding surfaces of the movable split mold and the fixed mold are completely connected. The mold rotates and the bending process is completed.

According to the present invention, when the rigidity of the glass plate is still high, it is possible to sufficiently soften the glass plate with a large load, and when it is necessary to bend the glass plate slowly, it can be bent and formed with a small load. Deep bending is possible without causing defects such as the plate slipping on the mortar die.

The material of the counterweight and the connecting member may be any material as long as it has sufficient heat resistance at the bending temperature, and stainless steel, cast metal, etc. are preferably used. As the connecting member, a chain or the like is preferably used as a member that can be tensioned and relaxed. Also, the weight of the counterweight is
It can be adjusted as appropriate depending on the size and thickness of the glass, the size of the mold, etc. The weight ratio of the main counterweight to the auxiliary counterweight can be similarly adjusted depending on the size and thickness of the glass, the size of the mold, etc. 0.5
It is preferable to adjust the amount of load to approximately double that.

Further, although the case where the load changes only in one stage has been described, a plurality of auxiliary counterweights and stoppers may be attached so that the load changes in multiple stages.

The bending die is made of a heat-resistant material that can withstand the forming temperature (580 to 700°C) of the glass plate in the heating/bending furnace, and has a bending surface corresponding to the middle curved part of the glass plate to be formed, and a deep bending part to be formed. A type having a bending surface corresponding to the above can be preferably used. The structure of such a bending mold may be either a planar shape that corresponds to the glass plate or a ring shape that can support the periphery of the glass plate, but in order to maintain the smooth surface of the glass plate, it is necessary to A ring-shaped one is preferable in that it minimizes the contact area between the surface of the bending die and the bending die.

As is clear from the above features, the present invention is extremely effective even when bending and forming two laminated blank glass sheets at the same time. In addition, in the peripheral area including the part to be deeply bent,
Various applications are possible without sacrificing the effect, such as printing colored ceramic color ink to form a colored band.

[Example] The present invention will be explained in detail below.

The glass plate was placed on the bending mold shown in Fig. 1, and passed through the heating and bending treatment stage in a heating and bending furnace together with the bending mold by means of a conveyor consisting of a trolley that moves via a chain conveyor. Afterwards, it was transported to a cooling stage outside the heating and bending furnace. At this time, in the above-mentioned heating and bending processing stage, the glass plate is heated to the glass softening temperature (550 to 650°C) by the heater in the heating furnace and softened, and then deep bent by its own weight along the forming surface of the bending die. In the cooling process stage, the formed glass plate is gradually cooled while being moved on a bending die at a controlled cooling rate for a predetermined period of time to prevent undesirable distortion, and then left to cool. did.

The shape of the obtained glass plate has an extremely deep arc depth of 450+ nm and a curvature of 270 mmH at the deep bending part.
Although the curvature was small, there was no noticeable perspective distortion, and it exhibited good optical properties.

[Effects of the Invention] As explained above, according to the method of bending and forming a glass plate of the present invention and the mortar mold therefor, the glass plate is heated to the glass softening temperature and the movable split mold and the fixed split mold are formed by the self-weight bending method. By forming into a shape that follows a split type bending die that has It can be bent and formed, and the degree of clarity of the formed shape of the glass plate can be increased.

[Brief explanation of drawings]

1 is a side view of a bending die suitable for the method of the invention; FIG.
The figure shows an enlarged perspective view of the main part, and FIG. 3 shows a side view of a conventional bending die. la...Movable split mold 1b...Fixed split mold 2...Main counterweight 3...Auxiliary counterweight 4...Connecting material (b) Fig. l

Claims (3)

[Claims] (1) A bending die used to bend a glass plate into a predetermined shape by placing a glass plate on it, heating it, and letting the glass plate hang under its own weight, which corresponds to the intermediate curved part of the predetermined shape. a fixed split mold having a bending surface; a bending surface corresponding to a side portion of the predetermined shape; and a direction in which the bending surface is continuous with the bending surface of the fixed split mold on both sides or one side of the fixed split mold. It has a movable split mold that is rotatable around a rotation axis, and the load of a counterweight that applies force so that the bending surface of the movable split mold is connected to the bending surface of the fixed split mold is used for bending. A bending mold that changes in multiple stages. (2) A bending die used to bend a glass plate into a predetermined shape by placing a glass plate on it, heating it, and letting the glass plate hang under its own weight, which corresponds to the intermediate curved part of the predetermined shape. a fixed split mold having a bending surface; a bending surface corresponding to a side portion of the predetermined shape; and a direction in which the bending surface is continuous with the bending surface of the fixed split mold on both sides or one side of the fixed split mold. a movable split mold that is rotatably provided around a rotation axis, and a movable split mold that is fixed to the movable split mold and is attached in a direction in which the molding surfaces of the movable split mold and the fixed split mold are connected to each other. an auxiliary counterweight that is connected to the main counterweight via a connecting member that can be tensioned and relaxed, and is rotatably attached to the fixed split mold; and fixed to the movable split mold. A bending die characterized by comprising: a stopper fixed to a fixed split mold so as to support the movable split mold while the movable split mold moves so that the molding surfaces of the split molds are connected to each other. (3) When bending a glass plate into a predetermined curved shape with deeply bent side portions, a fixed split mold having a bending surface corresponding to the intermediate curved portion of the predetermined shape; A movable mold that has a corresponding bending surface and is provided on both sides or one side of the fixed split mold so that the bending surface is movable around the rotation axis in a direction continuous with the bending surface of the fixed split mold. a step of placing a glass plate on a bending mold having a split mold; heating the glass plate placed on the bending mold in a heating furnace to perform self-weight bending, and bending the movable split mold; A method for bending a glass plate, characterized in that the load of a counterweight that applies force so that the forming surface is connected to the bending surface of a fixed split die is varied in multiple stages during bending.