WO2020162468A1 - Glass plate forming method - Google Patents

Abstract

The glass plate press-forming method of the invention comprises sandwiching a glass plate with two forming molds, forming the glass center portion of the glass plate by applying a first compressive force of 0.1 MPa or less in the mold clamping direction or without applying the compressive force, and forming the glass outer periphery portion by bringing a second compressive force to 0.1 to 10 MPa. Alternatively, the method includes applying the first compressive force of 0.1 MPa or less in the mold clamping direction from one of the pair of forming molds onto the glass plate, sandwiching the glass outer periphery portion of the glass plate between the pair of forming molds, delimiting, on the inner periphery side of the glass outer periphery portion, a space between the glass plate and the first forming mold disposed at the front end in the mold clamping direction, and supplying negative pressure to this space to cause the glass plate to be suctioned onto the first forming mold.

Description

Glass plate forming method

The present invention relates to a method for forming a glass plate.

Various methods are used to manufacture a glass press-molded product by heating and softening the glass material housed in the mold and pressing. For example, a molding apparatus has been proposed in which a plate-shaped glass material is sequentially conveyed to heating, pressing, and cooling stages provided in a chamber, and a press-molded product is continuously molded at each stage (Patent Document 1). ).

In such a molding device, the glass material is maintained at a heating temperature sufficient for processing the glass material by setting the molding die to a specified temperature during pressing. The glass material after molding is cooled and solidified, and finally cooled to a temperature of 200° C. or lower at which the molding die is not oxidized. As described above, in the glass material, the shape of the mold is accurately transferred at the time of pressing, and by holding this molded shape by cooling and solidifying, it becomes a press-molded product with high shape accuracy.

International Publication No. 2013/103102

By the way, in the above molding equipment, there was room for improvement in various aspects such as the productivity of molded products, the quality of shape and surface texture, etc., due to the complicated molding shape of glass materials and mass production.

An object of the present invention is to provide a glass plate molding method capable of molding with high shape accuracy and high throughput while reducing equipment costs even for molded products having complicated shapes.

The present invention has the following configurations.
(1) A method for forming a glass plate by heating the glass plate to form a desired shape,
Sandwiching the glass plate between a pair of molds,
By the forming die, the first pressurizing force of 0.1 MPa or less is not applied or applied to the glass central portion inside the outer peripheral edge of the glass plate in the mold clamping direction, and the outer peripheral edge of the glass central portion is used. A step of press-molding the glass plate by applying a second pressurizing force of 0.1 to 10 MPa different from the first pressurizing force to the outer peripheral portion of the glass plate up to the outer peripheral edge in the mold clamping direction. When,
A method for forming a glass plate having:
(2) A method of forming a glass plate by heating the glass plate to form a desired shape,
Sandwiching the glass plate between a pair of molds,
A pressure of 0.1 MPa or less is applied to the glass plate in the mold clamping direction from one of the pair of molding dies, and the outer peripheral edge of the glass plate starts from the outer periphery of the glass central portion inside the outer peripheral edge of the glass plate. The annular glass outer peripheral part between is sandwiched between the pair of molding dies, on the inner peripheral side of the glass outer peripheral part, the first molding die arranged ahead of the mold clamping direction, and the glass plate. The process of defining a space between
A step of supplying a negative pressure to the space defined between the glass plate and the first mold so that the glass plate is adsorbed to the first mold;
A method for forming a glass plate having:

According to the present invention, even a molded product having a complicated shape can be molded with high shape accuracy and high throughput while reducing the equipment cost.

FIG. 1 is a schematic process drawing showing a procedure for forming a glass plate into a curved shape. FIG. 2 is a schematic configuration diagram of the molding apparatus. FIG. 3 is a sectional view of a plurality of lamp heaters. FIG. 4 is a schematic plan view of the cross section along the line III-III shown in FIG. 2 as seen from above. FIG. 5 is a schematic explanatory view showing how the lower die is conveyed along the conveying direction from the preheating stage to the cooling stage. FIG. 6 is an enlarged sectional view of the molding stage. 7A is a cross-sectional view of the upper mold, and FIG. 7B is a cross-sectional view including the molding surface of the lower mold. FIG. 8 is a rear view of the upper die viewed from the direction B in FIG. 7(A). FIG. 9A is a cross-sectional view of the upper mold of the modification, and FIG. 9B is a cross-sectional view including the molding surface of the lower mold of the modification. FIG. 10 is a plan view of the glass plate. FIG. 11A is a schematic process explanatory view showing stepwise a process of forming a glass plate by bringing the lower mold and the upper mold shown in FIGS. 7A and 7B close to each other. FIG. 11B is a schematic process explanatory view showing stepwise how the lower die and the upper die shown in FIGS. 7A and 7B are brought close to each other to form the glass plate. FIG. 11C is a schematic process explanatory view showing stepwise how the lower die and the upper die shown in FIGS. 7A and 7B are brought close to each other to form the glass plate. FIG. 12 is a process explanatory view showing an outline of how a glass plate is formed by the second forming method. FIG. 13A is a schematic process explanatory view showing stepwise a process of forming a glass plate by bringing the lower mold and the upper mold of the modified example shown in FIGS. 9A and 9B close to each other. FIG. 13B is a schematic process explanatory view showing stepwise how the lower die and the upper die of the modified example shown in FIGS. 9A and 9B are brought close to each other to form the glass plate. FIG. 13C is a schematic process explanatory view showing, step by step, how the lower mold and the upper mold of the modification shown in FIGS. 9A and 9B are brought close to each other to mold the glass plate. FIG. 14 is a process explanatory view showing an outline of how a glass plate is formed by the fourth forming method. FIG. 15 is a schematic configuration diagram of a molding apparatus including a plurality of preheating stages, a molding stage, and a plurality of cooling stages. FIG. 16 is a graph showing an example of temperature changes of the lower die and the glass plate in the preheating stage, the forming stage, and the cooling stage. FIG. 17 is a schematic configuration diagram of a conventional molding apparatus as a reference example. FIG. 18 is a schematic configuration diagram of a molding apparatus showing another configuration example of the molding apparatus shown in FIG. 19A shows the molded shapes of Test Examples 1 and 2, FIG. 19B shows the molded shape of Test Example 3, FIG. 19C shows the molded shape of Test Example 4, and FIG. 19D shows the molded shape of Test Example 5. It is a schematic sectional drawing.

Hereinafter, embodiments of the present invention will be described in detail.
Here, a specific example of a molding apparatus and a molding method for molding a glass plate into a shape having a curved surface shape at least in part will be presented and described. However, the present invention is applicable to various materials such as materials, molding shapes, and sizes. It is also possible to change the configuration and procedure of the device as appropriate according to the manufacturing conditions.

In this specification, “to” indicating a numerical range is used to mean that numerical values described before and after the numerical range are included as a lower limit value and an upper limit value.

<Outline of glass plate forming procedure>
FIG. 1 is a schematic process diagram showing a procedure for forming a glass plate into a curved shape.
In the glass sheet forming apparatus 100, a preheating stage 11, a forming stage 13, and a cooling stage 15 are arranged in this order, and further, a loading unit 19 that carries in a glass sheet 17 before forming into the preheating stage 11, An unloading unit 21 that carries out the glass plate 17A after molding from the cooling stage 15.

In the preheating stage 11, the glass plate 17 carried in is heated to be softened. In the forming stage 13, the glass plate 17 which is heated and softened in the preheating stage 11 is subjected to press forming or the like to form a desired shape. In the cooling stage 15, the glass plate 17 formed by the forming stage 13 is gradually cooled to a temperature at which deformation is suppressed.

The glass plate 17 is loaded and unloaded from the loading section 19 and the unloading section 21 to each of the above stages. That is, in the loading section 19, the glass plate 17 before molding is placed on the lower mold (first molding mold) 23. The lower mold 23 on which the glass plate 17 is placed is conveyed to the preheating stage 11 and heated to a predetermined temperature in the preheating stage 11. The heated glass plate 17 is conveyed to the molding stage 13 together with the lower mold 23.

In the molding stage 13, the glass plate 17 is sandwiched between the upper mold (second molding mold) 25 and the lower mold 23 mounted on the molding stage 13, and the mold is clamped. As a result, the glass plate 17 is formed into a curved shape. After molding, the upper mold 25 is separated from the lower mold 23, and the processed glass plate 17A remaining in the lower mold 23 is conveyed to the cooling stage 15 together with the lower mold 23.

On the cooling stage 15, the heated glass plate 17A is gradually cooled. The glass plate 17A after the slow cooling is taken out from the lower mold 23 by the unloading section 21 and carried out.

In the molding apparatus of this configuration, in the molding stage 13, in addition to press molding in which the glass plate 17 softened by heating is pressed by the lower mold 23 and the upper mold 25, the glass plate is bent by its own weight (self-weight bending molding). Adsorption of the glass plate to the molding surface of the molding die (vacuum adsorption) and pressure bonding of the glass plate to the molding surface of the molding die (compressed air molding) are combined depending on the purpose. By selectively using such a plurality of pressure sources, curved surface molding with high shape accuracy is possible. Regarding the self-weight bending, if the glass plate 17 is placed on the lower die 23 and heated, the self-weight bending of the glass plate 17 occurs, but this can be given controllability. For example, when there is almost no difference between the bending start temperature due to its own weight and the press forming temperature and the influence of its own weight bending due to heating up to the press temperature is small, the application of self weight bending is not applied. On the other hand, when sufficient self-weight forming time before and after pressing is taken, gravity influences the shape after forming, so self-weight bending is applied. In this way, the self-weight bending can be controlled according to the waiting time and the waiting temperature before performing the press forming.

Each of the above-mentioned molding methods is the following molding method.
(1) Press molding means that a glass plate is placed between predetermined molding dies (lower mold, upper mold), the glass plate is softened, and a press load is applied between the upper and lower molding dies to obtain a glass plate. It is a method of bending the resin into a mold and molding it into a predetermined shape.
(2) Self-weight bend forming means that after the plate-shaped glass is placed on a predetermined forming die, the glass plate is heated to soften it, and the glass plate is bent by gravity to conform to the forming die to have a predetermined shape. It is a method of molding into.
(3) In vacuum forming, a glass plate is placed on a predetermined forming die, for example, a clamp forming die is placed on the glass plate to seal the periphery of the glass plate. Then, the closed space between the molding die and the glass plate is depressurized by a pump or the like to give a differential pressure to the front and back surfaces of the glass plate for molding.
(4) In the pressure molding method, a glass plate is placed on a predetermined mold, and for example, a clamp mold is placed on the glass plate to seal the periphery of the glass plate. Then, a positive pressure is applied to the upper surface of the glass plate by compressed air, and a differential pressure is applied to the front and back surfaces of the glass plate to form the glass plate.

<Glass material of molded object>
The glass plate that is the molded object has a thickness of, for example, 0.5 mm or more, preferably 0.7 mm or more. The thickness of the glass plate is 5 mm or less, preferably 3 mm or less, more preferably 2 mm or less. Within this range, the strength of the final product is less likely to break.

As the glass composition of the glass plate, alkali-free glass, soda lime glass, soda lime silicate glass, aluminosilicate glass, borosilicate glass, lithium aluminosilicate glass, borosilicate glass can be used. In particular, the glass forming apparatus of this configuration is excellent when aluminosilicate or aluminoborosilicate is used for the glass plate. These glass plates have a high Young's modulus and a high expansion coefficient, and high thermal stress is generated by heating the glass plates. For this reason, the deviation from the desired bent shape of the glass plate becomes large, and the value of the compressive stress may vary when the glass plate is further strengthened. In the glass forming apparatus of this configuration, since the glass plate has these glass compositions, it is possible to reduce the shape deviation even in the bent shape and suppress the variation in the compressive stress.

As a specific example of the glass composition, the composition is expressed in mol% based on the oxide, SiO ₂ is 50 to 80%, Al ₂ O ₃ is 0.1 to 25%, Li ₂ O+Na ₂ O+K ₂ O is 3 to A glass containing 30%, 0 to 25% of MgO, 0 to 25% of CaO and 0 to 5% of ZrO ₂ can be mentioned, but it is not particularly limited. More specifically, the following glass compositions may be mentioned. Note that, for example, “containing 0 to 25% of MgO” means that MgO may be contained up to 25% although it is not essential. The glass (i) is included in soda lime silicate glass, and the glasses (ii) and (iii) are included in aluminosilicate glass. The glass (v) is included in the silicate glass of lithium aluminum.
(I) With a composition expressed in mol% based on oxide, 63 to 73% of SiO ₂ , 0.1 to 5.2% of Al ₂ O ₃ , 10 to 16% of Na ₂ O, and K ₂ O of Glass containing 0-1.5%, Li ₂ O 0-5%, MgO 5-13% and CaO 4-10%.
(Ii) The composition expressed in mol% based on oxide is 50 to 74% for SiO ₂ , 1 to 10% for Al ₂ O ₃ , 6 to 14% for Na ₂ O, and 3 to 11% for K ₂ O. , Li ₂ O 0 to 5%, MgO 2 to 15%, CaO 0 to 6% and ZrO ₂ 0 to 5%, and the total content of SiO ₂ and Al ₂ O ₃ is 75% or less. , A glass having a total content of Na ₂ O and K ₂ O of 12 to 25% and a total content of MgO and CaO of 7 to 15%.
(Iii) The composition expressed in mol% based on the oxide is 68 to 80% for SiO ₂ , 4 to 10% for Al ₂ O ₃ , 5 to 15% for Na ₂ O, and 0 to 1% for K ₂ O. A glass containing 0 to 5% of Li ₂ O, 4 to 15% of MgO and 0 to 1% of ZrO ₂ .
(Iv) The composition expressed in mol% based on oxide is 67 to 75% for SiO ₂ , 0 to 4% for Al ₂ O ₃ , 7 to 15% for Na ₂ O, and 1 to 9% for K ₂ O. , Li ₂ O 0 to 5%, MgO 6 to 14% and ZrO ₂ 0 to 1.5%, the total content of SiO ₂ and Al ₂ O ₃ is 71 to 75%, Na ₂ O And a glass having a total content of K ₂ O of 12 to 20% and containing CaO of less than 1%.
(V) the composition viewed in mole percent on the oxide basis, of SiO ₂ 56 - 73%, the _{Al 2 O 3 10 ~ 24%} , the _{B 2 O 3 0 ~ 6%} , P 2 O 5 0 to 6%, Li ₂ O 2-7%, Na ₂ O 3-11%, K ₂ O 0-2%, MgO 0-8%, CaO 0-2%, SrO 0-5% A glass containing 0 to 5% of BaO, 0 to 5% of ZnO, 0 to ₂ % of TiO ₂ , and 0 to 4% of ZrO ₂ .

<Structure of molding device>
Hereinafter, one configuration example of the above-described molding device will be described in detail.
FIG. 2 is a schematic configuration diagram of the molding apparatus 100. FIG. 3 is a schematic plan view of the cross section along the line III-III shown in FIG. 2 as seen from above.
In the following description, the same reference numerals are given to members and parts that have the same effect, and the description thereof may be omitted or simplified. In addition, the embodiments described in the drawings are schematically illustrated to clarify the description of the present configuration, and are not accurately represented according to the actual size and scale of the product.

In the forming apparatus 100 shown in FIG. 2, the direction from the left side to the right side in the horizontal direction is the glass plate conveyance direction TD, and the preheating stage 11, the molding stage 13, and the cooling stage 15 are arranged in this order from the upstream side of the conveyance direction TD. It The preheating stage 11, the molding stage 13, and the cooling stage 15 are housed in the internal space of the chamber 27. The inside of the chamber 27 is purged with an inert gas such as nitrogen gas to reduce the gas concentration of the gas that adversely affects the glass molding.

The chamber 27 has a carry-in port 29 for carrying the glass plate and the lower mold 23 into the chamber 27, and a carry-out port 31 for carrying out the glass plate and the lower mold 23 after molding. The loading section 19 shown in FIG. 1 is connected to the carry-in port 29, and the unloading section 21 shown in FIG. 1 is connected to the carry-out port 31 (not shown). Further, shutters (not shown) are provided at the carry-in port 29 and the carry-out port 31, and the atmosphere in the chamber 27 is kept constant by closing the shutters except when carrying in and carrying out the glass plate. A plurality of openings 101 are formed in the chamber 27, and a support shaft 37 described below is inserted into each of the openings 101. The support shaft 37 and the chamber 27 are sealed with a bellows structure (not shown). The chamber 27 may have a closed structure for closing the inert gas, or a semi-closed structure for constantly supplying the inert gas to make the inside of the chamber 27 at a positive pressure.

In the preheating stage 11 shown in FIG. 2, an upper heater (heating part for heating) 35 that heats the glass plate and the lower mold 23 to a desired heating temperature is arranged above the glass plate transport surface. The upper heater 35 is preferably arranged so as to face the lower mold 23 and includes a plurality of lamp heaters 36 supported by a fixed frame (not shown) as heat sources. As the lamp heater 36, for example, an infrared lamp heater is used. As the infrared lamp heater, various known heaters such as carbon lamps and halogen lamps can be used, and any heating element capable of radiant heating can be used.

FIG. 3 is a sectional view of the plurality of lamp heaters 36.
The lamp heater 36 has a heating wire 36A that generates heat when energized, and a tube material 36B such as quartz that surrounds the heating wire 36A. A ceramic coat layer 40 is formed on the inner peripheral surface or the outer peripheral surface of the pipe material 36B, leaving the irradiation window 38. The opening angle (center angle) θ of the irradiation window 38 with the heating wire 36A as the center is determined according to the distance Ld from the center of the lamp heater 36 to the lower mold 23 that is the object to be heated and the arrangement pitch Lc of the lamp heater 36. Thus, the lower die 23 is uniformly irradiated with heat rays. Here, as an example, the opening angle θ is set to 60°.

The heating region of the upper heater 35 (the region where the lamp heaters 36 are arranged) is preferably wider than the outer edge of the lower mold 23 in the horizontal plane, in which case the entire lower mold 23 can be heated uniformly.

Above the upper heater 35, the water cooling plate 39 supported by the support shaft 37 described above is arranged. It is desirable that a reflective film is provided on the surface of the water cooling plate 39 facing the upper heater 35. A channel for cooling water is formed in the water cooling plate 39, and the cooling water supplied and discharged through the support shaft 37 is circulated. The water cooling plate 39 suppresses unnecessary heating by the upper heater 35 to surrounding members other than the lower mold 23 and the glass plate.

A heat diffusion plate 41 is arranged below the lower mold 23 with a gap. A lower heater (heating part for heating) 43 is disposed below the heat diffusion plate 41. The heat diffusion plate 41 is made of a material having excellent heat conductivity and uniformly transfers the heat generated by the lower heater 43 to the lower mold 23. As the material of the heat diffusion plate 41, for example, tungsten carbide, carbon, cemented carbide, copper, iron, stainless steel material or the like can be used. As the lower heater 43, a contact heating type stage heater or the like can be used, but the same radiation heating type configuration as the upper heater 35 may be used.

A water cooling plate 47 is arranged below the lower heater 43. The water cooling plate 47 is supported by a support body 45 fixed to the lower part of the chamber 27, and suppresses unnecessary heating of the peripheral members other than the heat diffusion plate 41 and the lower mold 23 by the lower heater 43. The water cooling plate 47 has the same configuration as the water cooling plate 39 described above, and cooling water is supplied and discharged from the support body 45.

The gap between the lower mold 23 and the heat diffusion plate 41 in the cooling stage 15 is not particularly limited, but if it is too large, the heating efficiency decreases, and if it is too small, it becomes difficult to suppress the temperature deviation of the glass plate. The lower limit of the gap is 1 mm. The upper limit of the gap is 10 mm.

A heat insulating frame 51 is arranged so as to surround the upper surface side of the lower mold 23 on which the glass plate is placed and the outer periphery of the stage on the side of the upper heater 35, the water cooling plate 39 and the support shaft 37. The heat insulating frame 51 covers the side of the glass plate placed on the lower mold 23 arranged in the stage.

As the heat insulation frame 51, for example, a heat insulation board made of a material mainly containing calcium silicate can be used. Besides, for example, a metal plate such as a stainless steel material may be used. As shown in FIG. 4, the heat insulating frame is preferably a frame having a rectangular horizontal cross section that surrounds a wide range outside the outer periphery of the lower mold 23. The heat insulating frame 51 may include a lid that covers the upper portion of the frame.

Also, it is preferable that the heat insulating frames 53 and 55 having the same configuration are arranged also in the molding stage 13 and the cooling stage 15. In order to improve the molding quality of the obtained glass plate, it is particularly important to reduce the temperature deviation of the glass plate in each stage. Therefore, it is preferable to provide a heat insulating frame on all of the stages. According to this, the temperature distribution in the internal space covered with the heat insulating frames 51, 53, 55 can be made uniform. Furthermore, since the outer sides of the heat insulating frames 51, 53, 55 are surrounded by the chamber 27, heat inflow and outflow with the outside do not easily occur in the heat insulating frame bodies 51, 53, 55, and a more uniform temperature distribution is obtained. can get. Thereby, the thermal efficiency is improved, the processing time in each stage can be shortened, and the temperature deviation of the glass plate in each stage can be reduced.

As shown in FIG. 4, a lower mold 23 is arranged on each of the preheating stage 11, the molding stage 13, and the cooling stage 15. Each of the lower molds 23 is provided with a pair of mold supporting rods 61 projecting outward on side surfaces 23a and 23b on both sides orthogonal to the transport direction TD. The respective mold supporting rods 61 are supported by the mold conveying units 63A and 63B arranged on both sides of the lower mold 23. Although detailed description of the mechanism is omitted, the mold transfer units 63A and 63B use a walking beam transfer mechanism to move the plurality of lower molds 23 arranged along each stage along the transfer direction TD. Transport.

FIG. 5 is a schematic explanatory view showing how the lower die 23 is conveyed in the conveying direction TD from the preheating stage 11 to the cooling stage 15.
The mold transfer units 63A and 63B support the mold supporting rods 61 protruding from each of the plurality of lower molds 23, and move the plurality of lower molds 23 from the preheating stage 11 to the molding stage 13 by the walking beam method. From the sheet to the cooling stage 15 at the same time. The vertical displacement of the lower mold 23 during the transportation is performed within a range that does not interfere with the fixed side members such as the heat insulating frames 51, 53, 55 and the heat diffusion plate 41.

Next, the cooling stage 15 shown in FIG. 2 will be described.
Above the lower mold 23 of the cooling stage 15, a heat diffusion plate 65, an upper heater (heating unit for lowering temperature) 67 similar to the preheating stage 11, and a water cooling plate 59 are arranged in this order. The heat diffusion plate 65 has the same configuration as the heat diffusion plate 41 described above. The water cooling plate 59 is fixed to the upper part of the chamber 27 and is supported by a support shaft 71 having a flow path for cooling water formed therein.

Like the preheating stage 11, a heat diffusion plate 73, a lower heater (heating unit for lowering temperature) 75, and a water cooling plate 77 are arranged below the lower mold 23 of the cooling stage 15. The water cooling plate 77 is supported by a support 79 fixed to the lower part of the chamber 27, and suppresses unnecessary heating of the peripheral members other than the heat diffusion plate 73 and the lower mold 23 by the lower heater 75. The water cooling plate 77 has the same configuration as the water cooling plate 39 described above, and cooling water is supplied and discharged from the support 79.

The lower mold 23 of the cooling stage 15 and the heat diffusion plate 65 and the lower mold 23 and the heat diffusion plate 73 may be closely contacted with each other, but a temperature distribution of the lower mold 23 is provided by providing a gap. It is preferable because it can be made more uniform.

Next, the molding stage 13 shown in FIG. 2 will be described.
FIG. 6 is an enlarged sectional view of the molding stage 13.
Above the lower mold 23 of the molding stage 13, the upper mold 25, the heat diffusion plate 81, the upper heater (heat retaining heating unit) 83, the heat insulating plate 85, and the water cooling plate 87 are arranged in this order.

The upper mold 25 is connected to a plunger (not shown), and is supported so as to be movable up and down between a molding position where the lower mold 23 is clamped and a retracted position above the molding position. The upper mold 25 is arranged at the retracted position except when the lower mold 23 is being conveyed, such as when it is being molded. Further, the upper mold 25 may be fixed in the molding stage 13 and the lower mold 23 may be lifted during the conveyance of the lower mold 23 to clamp the mold. In that case, the upper die moving mechanism can be omitted, and the equipment cost can be reduced.

The water cooling plate 87 is supported by a support shaft 89 fixed to the upper part of the chamber 27, and suppresses unnecessary heating of peripheral members other than the upper mold 25 and the heat diffusion plate 81 by the upper heater 83. The water cooling plate 87 has the same configuration as the water cooling plate 39 described above, and cooling water is supplied and discharged from the support shaft 89.

For the heat insulating plate 85, a known heat insulating material such as ceramics, stainless steel, die steel, high speed steel (high speed steel) can be used. When a metal-based material is used, it is preferable that the surface be coated with CrN, TiN, TiAlN or the like. Further, the surface of the heat insulating plate 85 may have a rough structure. In that case, a minute gap is generated between the water cooling plate 39 and a higher heat insulating effect.

A heat diffusion plate 91, a lower heater (heating unit for heating) 93, a heat insulating plate 85, and a water cooling plate 97 are arranged in this order below the lower mold 23 of the molding stage 13. The water cooling plate 97 is supported by a support 99 fixed to the lower part of the chamber 27, and suppresses unnecessary heating of the peripheral members other than the heat diffusion plate 91 and the lower mold 23 by the lower heater 93. The water cooling plate 97 has the same configuration as the water cooling plate 39 described above, and cooling water is supplied and discharged from the support body 99.

The upper die 25 of the molding stage 13 is attached to a cylinder (not shown) that is driven in the vertical direction, and is supported so as to be vertically movable by driving the cylinder. As the cylinder, an air cylinder, a hydraulic cylinder, a servo cylinder using an electric servomotor, or the like can be used.

The upper die 25 of the molding stage 13 is in surface contact with the heat diffusion plate 81, and heat from the upper heater 83 is evenly transferred to the upper die 25. The lower die 23 of the molding stage 3 is in surface contact with the heat diffusion plate 91 so that heat from the lower heater 93 is evenly transferred to the lower die 23. Depending on the molding conditions and the like, the upper die 25 and the heat diffusion plate 81 may be separated from each other, and the lower die and the heat diffusion plate 91 may be separated from each other.

7A is a sectional view of the upper die 25, and FIG. 7B is a sectional view including the molding surface 111 of the lower die 23. FIG. 8 is a rear view of the upper die 25 seen from the direction B in FIG. 7(A).
As shown in FIGS. 7A and 8, the upper mold 25 arranged rearward in the mold clamping direction has an annular protrusion 113. The protrusion 113 is provided on the upper die 25 corresponding to the outer edge portion of the molding surface 111 of the lower die 23 shown in FIG. 7B so as to project toward the lower die 23. The protruding portion 113 has an inclined surface 113 a whose amount of protrusion gradually increases from the outer periphery of the upper mold 25 toward the center. The molding surface 111 has a shape that matches the molding shape of the glass plate. That is, the bottom surface of the annular protrusion 113 shown in FIG. 8 is a flat bottomed groove 25a.

The lower mold 23 arranged at the tip in the mold clamping direction shown in FIG. 7B has a plurality of suction holes 115 for vacuum forming which are opened in the molding surface 111. The suction hole 115 is connected to a suction source such as a suction pump (not shown). By driving the suction pump, the gas in the space between the lower mold 23 and the glass plate 17 is sucked at a predetermined timing to bring the glass plate 17 into close contact with the molding surface 111.

The lower mold 23 and the upper mold 25 can be made of materials such as carbon, stainless steel, ceramics, and cemented carbide. In particular, it is preferable to use carbon from the viewpoint of making the heat distribution uniform.

The shape of the protrusion 113 of the upper mold 25 is not limited to this. The protruding portion 113 may have a flat protruding surface without forming the above-described bottomed groove 25a.
9A is a cross-sectional view of a modified upper die 25A, and FIG. 9B is a cross-sectional view including a molding surface 111A of a modified lower die 23A.

The upper mold 25A of the modification has a protrusion 113A protruding toward the lower mold 23B of the modification. The protrusion 113A is formed with an inclined surface 113a whose projection amount gradually increases from the outer periphery of the upper mold 25A toward the center, and the top has a flat top surface 113b.
Further, the lower mold 23A has a molding surface 111A having a shape that matches the molding shape of the glass plate, similarly to the lower mold 23 shown in FIG. The suction hole 115 is provided at a position where the curvature of the molding surface 111A is maximum. In the case of this configuration, the region in the plan view annular shape where the inclined surface 111a corresponding to the inclined surface 113a of the upper die 25A and the bottom surface 111b corresponding to the top surface 113b are connected has the maximum curvature. A plurality of suction holes 115 are provided so as to open at least a part of this annular region.

The projection 113A of the upper mold 25A and the molding surface 111A of the lower mold 23A of this configuration have the curvature of the projection 113A smaller than the curvature of the molding surface 111A at corresponding positions. According to this, when the glass plate 17 is sandwiched between the inclined surfaces 111a and 113a, the contact area with the glass plate 17 becomes small, and the glass plate 17 is easily deformed or moved. Therefore, the glass plate 17 can be made to follow the forming surface 111A faithfully, and the shape accuracy can be improved.

The upper heaters 35, 67, 83 and the lower heaters 43, 75, 93 in the preheating stage 11, the molding stage 13, and the cooling stage 15 shown in FIG. 2 are all connected to a temperature control unit (not shown), and It is set to the individual set temperature. The temperature control unit realizes heating, heat retention, and gradual cooling processing at each stage by control operations such as proportional control, PI control, and PID control.

In addition, in the above-described forming apparatus 100, the glass plate transport direction TD is horizontal, but it may be a direction inclined from the horizontal direction, such as the vertical direction. In that case, the lower mold 23 and the upper mold 25 may not be arranged above and below, but by adjusting the heating temperature of the glass plate and not lowering the viscosity of the glass plate too much, the lower mold is suppressed while suppressing the influence of gravity. It can be molded between 23 and the upper mold 25.

<Glass plate molding procedure>
Next, a specific procedure for forming the glass plate 17 into a curved shape using the forming apparatus 100 having the above-described configuration and its operation will be described.

The glass plate 17 before molding is placed on the lower mold 23 of the loading unit 19 shown in FIG. 1 by a transfer means such as a robot arm (not shown) or manually by an operator.

The lower mold 23 of the loading unit 19 is transferred to the preheating stage 11 while the glass plate 17 is placed by the mold transfer units 63A and 63B shown in FIG. It is preferable that the lower mold 23 is preheated to a temperature higher than room temperature before the glass plate 17 is placed, because the heating time in the preheating stage 11 can be shortened. For example, the temperature of the lower mold 23 when the glass plate 17 is placed is preferably 300° C. or higher, and more preferably 500° C. or higher.

(Preheating process)
In the preheating stage 11 shown in FIG. 2, the upper heater 35 and the lower heater 43 heat the glass plate 17 on the lower mold 23 to a target heating temperature (for example, 500° C. to 700° C.).

The temperature suitable for press-molding the glass plate 17 depends on the composition of the glass plate 17 itself, but if the temperature is too low, the glass plate 17 will not soften sufficiently. Therefore, in the preheating stage 11, heating is performed so that the glass transition point of the glass plate 17 is preferably Tg or higher, more preferably Tg+40° C. or higher, and further preferably Tg+80° C. or higher. On the other hand, if the temperature of the glass plate 17 is too high, the glass plate 17 is excessively softened and becomes unsuitable for maintaining its shape. Therefore, in the preheating stage 11, the glass plate 17 is heated to preferably Tg+200° C. or lower, more preferably Tg+150° C. or lower, and further preferably Tg+120° C. or lower.

From the same viewpoint as above, in the preheating stage 11, the viscosity of the glass plate 17 is preferably 5.22×10 ¹¹ Pa·s or more, more preferably 1.97×10 ¹⁰ Pa·s or more, further preferably Is heated to 1.81×10 ⁹ Pa·s or more. In the preheating stage 11, the viscosity of the glass plate 17 is preferably 5.94×10 ⁶ Pa·s or less, more preferably 4.16×10 ⁷ Pa·s or less, and further preferably 1.65×10 ⁸ Pa. -Heating so that it becomes s or less.

From the viewpoint of the surface quality of the obtained glass plate molded product, it is preferable to uniformly heat the glass plate 17 in the preheating stage 11. That is, it is preferable to reduce the temperature deviation of the glass plate 17 during heating in the preheating stage 11. Specifically, the temperature deviation of the glass plate 17 during heating in the preheating stage 11 is preferably less than 30°C, more preferably less than 20°C, and even more preferably less than 10°C.

The temperature distribution of the region of the lower mold 23 in contact with the glass plate 17 during heating is preferably less than 30°C, more preferably less than 25°C, and even more preferably less than 20°C.

(Molding process)
The glass plate 17 heated to the target heating temperature is conveyed to the molding stage 13 together with the lower mold 23. In the molding stage 13, an external force such as a press is applied to the heated glass plate 17 in the mold clamping direction to mold it into a desired shape.

On the molding stage 13, the upper mold 25 arranged at the retracted position is lowered, and the glass plate 17 is sandwiched between the upper mold 25 and the lower mold 23 to mold the glass plate 17. Details of this molding process will be described later. On the molding stage 13, the upper heater 83 and the lower heater 93 keep the temperature of the glass plate 17 heated by the preheating stage 11 constant.

The temperature of the glass plate 17 in the molding stage 13 is preferably suppressed to 20° C. or less from the above-mentioned heating temperature in the preheating stage 11. Further, from the viewpoint of the surface quality of the obtained glass plate molded body, it is preferable to uniformly heat the glass plate 17 on the molding stage 13. Specifically, it is preferable that the temperature deviation of the glass plate 17 being formed by the forming stage 13 is within 20°C.

When the glass plate 17 is molded, the upper mold 25 moves up and returns to the retracted position. Then, the lower mold 23 is conveyed to the cooling stage 15 together with the molded glass plate 17A.

(Cooling process)
In the cooling stage 15, the set temperature of the upper heater 67 and the lower heater 75 is set to a temperature lower than the target heating temperature, and the glass plate 17A and the lower mold 23 are gradually cooled. In the cooling stage 15, the glass plate 17 is gradually cooled until the shape of the heated and molded glass plate 17A becomes stable.

On the cooling stage 15, the glass plate 17A is gradually cooled while adjusting the heating temperature by the upper heater 67 and the lower heater 75. If the cooling speed in the cooling stage 15 is too fast, the glass plate 17A is likely to be deteriorated or have a temperature deviation. Therefore, the cooling rate of the glass plate 17A in the cooling stage 15 is preferably 30° C., 20° C., more preferably 30° C., and further preferably 40° C. The temperature distribution of the glass plate 17A during cooling is preferably 30° C. or lower, more preferably 25° C. or lower, and further preferably 20° C. or lower.

After being gradually cooled, the glass plate 17A is transferred to the outside of the chamber 27 and then taken out by the unloading section 21 as shown in FIG. In the unloading section 21, the glass plate 17A, which is placed in a lower mold having a temperature of 300° C. or higher, preferably 500° C. or higher, after molding and slow cooling is taken out from the mold surface. The glass plate 17 may be taken out by a transfer means such as a robot arm (not shown) or manually by an operator.

<Equalization effect of temperature distribution>
The above-mentioned uniform temperature distribution of the glass plates 17 and 17A has the effect of confining heat by the heat insulating frames 51, 53 and 55, and the high heat shielding effect from the outside by the chamber 27 outside the heat insulating frames 51, 53 and 55. Further, the heat diffusion plates 41, 65, 73, 81, 91 achieve a uniform heating effect of the heater, and other synergistic effects. Further, the radiant heating by the upper heater 35 of the preheating stage 11, the heat transfer heating from the lower heater 43, the heat transfer heating from the upper heater 83 and the lower heater 93 of the molding stage 13, and the upper heater 67 and the upper heater 67 at the time of the cooling stage. Radiation heating via the heat diffusion plates 65 and 73 by the lower heater 75 causes each stage to have a different heating form. Further, the upper heater and the lower heater of each stage can be heated at their respective set temperatures, and fine temperature control is possible.

By individually controlling the heating for each stage and each heater, the temperature distribution of the glass plates 17, 17A can be made uniform at a high level. Also, fine adjustment according to the location becomes easy, and the heat treatment as designed can be realized accurately. Further, since the heating atmosphere is covered by the heat insulating frames 51, 53, 55 and the chamber 27, the heat outflow to the outside is suppressed, and as a result, the responsiveness of the heating control and the temperature lowering control is enhanced, and the desired temperature is increased. Can be uniformly reached in a short time.

Further, since the die transfer parts 63A and 63B are configured to transfer the lower die 23 by the walking beam method, the moving speed between the stages can be increased. Therefore, heat loss due to heat radiation between the stages is suppressed, and the temperature distribution can be made uniform.

The arrangement of the heat diffusion plates 41, 65, 73, 81, 91 may be omitted depending on the molding conditions. However, by providing the heat diffusion plate, the temperature deviation of the glass plates 17, 17A in each stage Can be kept small.

<Details of molding process>
Next, the method of forming the glass plate 17 on the forming stage 13 and the structure of the forming die will be described in detail.

First, the shape of the glass plate 17 used for molding will be defined.
FIG. 10 is a plan view of the glass plate 17.
The glass plate 17 has a glass central portion 121 inside the glass-shaped outer peripheral edge 17a and a glass outer peripheral portion 123 between the central peripheral portion 121a of the glass central portion 121 and the outer peripheral edge 17a. In FIG. 10, the outer peripheral portion 123 is hatched. In the molding step, at least a part of the glass central part 121 is molded into a curved shape.

(First molding method)
11A, 11B, and 11C are schematic steps showing stepwise a process of forming the glass plate 17 by bringing the lower mold 23 and the upper mold 25 shown in FIGS. 7A and 7B close to each other. FIG.
As shown in FIG. 11A, the glass plate 17 is placed on the molding surface 111 of the lower mold 23 in a state where the outer peripheral edge 17 a of the glass plate 17 is in contact. When the upper mold 25 is lowered toward the lower mold 23, the protrusion 113 of the upper mold 25 comes into contact with the glass plate 17 placed on the lower mold 23.

The upper die 25 has a portion that comes into contact with the glass plate 17 and a portion that does not come into contact with it, and only the inclined surface 113 a of the protrusion 113 comes into contact with the glass outer peripheral portion 123 of the glass plate 17. Then, as shown in FIG. 11B, when the upper mold 25 is further lowered, the glass plate 17 is pressed into a shape protruding downward due to the inclination of the inclined surface 113a of the protrusion 113. That is, the upper mold 25 can deform the glass plate 17 toward the lower mold 23 only by contacting the glass plate 17 in an annular shape. Further, the glass plate 17 also bends downward due to its own weight and deforms along the molding surface 111 of the lower mold 23.

Next, as shown in FIG. 11C, a negative pressure is supplied from the suction holes 115 so that the glass plate 17 is vacuum-sucked to the molding surface 111. As a result, the glass plate 17 comes into close contact with the molding surface 111, and the curved shape of the molding surface 111 is transferred to the glass plate 17. Therefore, even a portion where the glass plate 17 and the molding surface 111 are difficult to be brought into close contact with each other only by press molding can be surely brought into close contact, and even a complicated shape which is difficult only by press molding can be easily formed.

The position, number, size, etc. of the suction holes 115 are not particularly limited, but it is preferable to form the suction holes 115 in the molding surface 111 where it is difficult to bring the glass plate 17 into close contact only by press molding. Further, the size of the suction hole 115 is preferably appropriately adjusted so that the trace of the suction hole 115 does not remain on the glass plate 17 or is not conspicuous even if it remains.

Normally, in press molding a glass plate, the entire surface of the glass plate is sandwiched and formed in contact with the mold. Therefore, in order to secure the surface quality of the obtained glass plate molded product, it is molded at a relatively low temperature. Therefore, it takes a relatively long time to deform the glass plate into a desired shape. Therefore, when molding a complicated shape, it has been difficult to mold in a low temperature range where surface quality can be secured. On the other hand, when molding is performed using the lower mold 23 and the upper mold 25 having the above configuration, the upper mold 25 does not come into contact with the glass central portion 121 of the glass plate 17. Therefore, even if the glass is molded at a relatively high temperature, a glass plate molded product having excellent surface quality can be obtained without adversely affecting the glass central portion 121 such as surface roughness due to contact with the molding die. As described above, since the molding stage 13 having this configuration can perform molding at a relatively high temperature, the molding can be completed in a short time. That is, by using the above-mentioned molding die, a glass plate molded product having excellent surface quality can be obtained in a short time.

In addition, the lower mold 23 and the upper mold 25 of this configuration are molds for obtaining a glass plate molded product in which the entire glass central portion 121 is bent with a constant curvature, but the shapes of the lower mold 23 and the upper mold 25 are The shape is not limited to the illustrated example. The shapes of the lower mold 23 and the upper mold 25 can be appropriately changed according to the target shape to be molded.

The lower mold 23 and the upper mold 25 of this configuration realize molding that combines press molding, vacuum molding, and gravity bending by gravity, but depending on the material, molding conditions, etc., press molding and weight excluding vacuum molding can be performed. It is possible to perform molding only by molding.

(Second molding method)
In the first molding method, three types of molding including press molding, vacuum molding, and self-weight bending molding are combined, while in the second molding method, pressure molding is further combined.

FIG. 12 is a process explanatory view showing an outline of how the glass plate 17 is formed by the second forming method. The forming die in this case has the same configuration as the forming die of the first forming method except that the gas ejection holes 125 for compressed air forming are formed inside the annular projection 113 of the upper die 25B. ..

The gas ejection hole 125 is usually provided in a portion of the upper mold 25B that does not contact the glass plate 17. The number and size of the gas ejection holes 125 are not particularly limited.

When the press molding and the pressure molding are used together by using the lower mold 23 and the upper mold 25B having the above-described configuration, the protrusion 113 of the upper mold 25B is brought into contact with the glass outer peripheral portion 123 of the glass plate 17, and then the gas ejection hole is formed. Gas is ejected from 125. Then, the glass plate 17 is pressed against the molding surface 111 of the lower mold 23. That is, since the protrusion 113 is formed in an annular shape and contacts the glass plate 17 in an annular shape, a closed space 129 is formed between the molding surface 111 of the lower mold 23 and the glass plate 17. Gas is supplied to the closed space 129, and the pressure in the closed space 129 becomes positive pressure. As a result, the glass plate 17 is pressed against the molding surface 111.

Further, the above-described vacuum forming and forming by gravity are performed at the same time as the above-described pressure forming, so that the glass plate 17 can be made to follow the forming surface 111 more quickly and more reliably, and it is necessary to complete forming. You can save time. As described above, by combining press molding with at least one of vacuum molding, pressure molding, and gravity bending molding, molding of a complicated shape can be easily realized and the molding time can be further shortened.

Further, the vacuum forming and the pressure forming can be performed at any timing during the execution of the press forming, and the order of execution may be the order of press forming, vacuum forming and pressure forming. The order of vacuum forming may be used. By performing the press forming before the vacuum forming and the pressure forming, the positioning of the glass plate 17 with respect to the forming surface 111 can be performed more reliably.

Further, by performing each molding at the same time, it is possible to further improve the adhesion between the glass plate 17 and the molding surface 111, and it becomes easy to process the glass plate 17 into a shape that easily causes wrinkles.

(Third molding method)
FIG. 13A, FIG. 13B, and FIG. 13C show stepwise the process of forming the glass plate 17 by bringing the lower mold 23A and the upper mold 25A of the modified example shown in FIGS. It is a schematic process explanatory drawing shown.
As shown in FIG. 13A, the glass plate 17 is placed on the molding surface 111A of the lower mold 23A while the outer peripheral edge 17a of the glass plate 17 is in contact therewith. When the upper mold 25A is lowered toward the lower mold 23A, the top surface 113b of the projection 113A of the upper mold 25A comes into contact with the glass plate 17 placed on the molding surface 111A of the lower mold 23A.

At this time, the top surface 113b of the upper mold 25A is in surface contact with the glass plate 17 to disperse the pressure on the glass plate 17 as the upper mold 25A descends. That is, a light contact state is established. Then, as shown in FIG. 13B, the upper mold 25 is further lowered, and the glass plate 17 is pressed by a light load (0.1 MPa or less) into a shape in which the glass plate 17 is convex downward by the inclined surface 113a of the protrusion 113A. It At this time, a gap 117 communicating with the suction hole 115 is formed between the bottom surface 111b of the lower mold 23A and the glass plate 17. In other words, the top surface 113b of the protrusion 113A of the upper die 25A and the bottom surface 111b of the molding surface 111A of the lower die 23A are shaped so as not to come into contact with each other even when the die is clamped.

Next, as shown in FIG. 13C, a negative pressure is supplied from the suction holes 115 into the gap 117, whereby the glass plate 17 is vacuum-sucked to the molding surface 111A. As a result, the glass plate 17 comes into close contact with the molding surface 111A, and the curved shape of the molding surface 111A is transferred to the glass plate 17. In the process of forming from FIG. 13B to FIG. 13C, the pressing pressure is preferably kept lower than the light load (0.1 MPa or less) in FIG. 13B.

By providing the suction hole 115 at a position where the curvature of the molding surface 111A of the lower mold 23A is maximized, the gap 117 between the glass plate 17 and the molding surface 111A is directed from the center side of the bottom surface 111b to the peripheral side. Then, the glass plate 17 gradually comes into close contact with the molding surface 111A and disappears. Then, finally, the glass plate 17 comes into close contact with the portion of the molding surface 111A where the curvature is maximum. In this way, the glass plate 17 is transferred from the state in which the glass plate 17 is in contact with the top surface 113b of the protrusion 113A of the upper mold 25A to the bottom surface 111b of the molding surface 111A of the lower mold 23A without creating a gap.

Since the glass outer peripheral portion 123 is lightly pressed between the inclined surface 113a of the upper mold 25A and the inclined surface 111a of the lower mold 23A, the glass outer peripheral portion 123 is easily pressed by the suction holes 115. It can be deformed to the bottom surface 111b side. Therefore, the glass plate 17 is not locally constrained by the glass outer peripheral portion 123, and the entire glass plate 17 is adhered along the molding surface 111A with a substantially uniform pressure.

According to this molding method, the operation of transferring the shape of the glass plate 17 along the molding surface 111A of the lower mold 23A is substantially performed by vacuum suction. Therefore, since a uniform pressure distribution is generated within the glass surface, high-quality molding can be performed on the plate surface of the glass plate 17 without causing indentations or wrinkles due to local mold contact by the press of the upper mold 25A. You can do it. Further, since the desired shape is processed by vacuum suction, it is possible to perform molding with high accuracy and high quality even in a complicated shape which is difficult only by press molding.

(Fourth molding method)
In the fourth molding method, pressure molding is further combined with the third molding method.
FIG. 14 is a process explanatory view showing an outline of how the glass plate 17 is formed by the fourth forming method. The forming die in this case has the same configuration as the forming die of the third forming method except that the gas ejection holes 125 for compressed air forming are formed inside the protrusion 113A of the upper die 25C.

Similar to the case of the second molding method described above, the opening of the gas ejection hole 125 is usually provided in a portion of the upper mold 25B that does not contact the glass plate 17. The number and size of the gas ejection holes 125 are not particularly limited.

When the press molding and the pressure molding are used together by using the lower mold 23A and the upper mold 25C having the above-described configuration, the protrusion 113A of the upper mold 25C is brought into contact with the glass outer peripheral portion 123 of the glass plate 17, and then the gas ejection hole is formed. Gas is ejected from 125. Then, the glass plate 17 is pressed against the molding surface 111A of the lower mold 23A. That is, since the contact area between the projection 113A and the glass plate 17 is annular, a closed space 129 is formed between the molding surface 111A of the lower mold 23A and the glass plate 17. Gas is supplied to the closed space 129, and the pressure in the closed space 129 becomes positive pressure. As a result, the glass plate 17 is pressed against the molding surface 111A.

The above-described gas ejection from the gas ejection hole 125 may be performed after the vacuum suction of the glass plate 17 by the suction hole 115 or before the vacuum suction.

<Example of configuration of other molding device>
The glass plate forming apparatus 100 may include a plurality of preheating stages 11 and a plurality of cooling stages 15.
FIG. 15 is a schematic configuration diagram of a molding apparatus 200 including a plurality of preheating stages 11, a molding stage 13, and a plurality of cooling stages 15.

The preheating stages 11 are provided at four locations (PH1 to PH4) along the transport direction TD of the lower die 23, and the cooling stages 15 are provided at four locations (C1 to C4) along the transport direction TD of the lower die 23. To be The molding stage 13 is provided at one location (PM1) between the preheating stage 11 and the cooling stage 15.

The heating temperature of PH1 to PH4 of the preheating stage 11 is set stepwise along the transport direction TD. As a result, the lower mold 23 and the glass plate 17 are gradually heated as they are transported in the transport direction TD, and are heated until the target heating temperature, which is the molding temperature, is reached.

The heating temperatures of C1 to C4 of the cooling stage 15 are set gradually low along the transport direction TD. As a result, the lower mold 23 and the glass plate 17 are gradually cooled as they are transported in the transport direction TD, and are gradually cooled from the target heating temperature.

FIG. 16 is a graph showing an example of temperature changes of the lower mold 23 and the glass plate 17 in the preheating stage 11, the molding stage 13, and the cooling stage 15.
The glass plate 17 supplied to the PH1 of the preheating stage 11 from the loading unit 19 (LD) shown in FIG. 15 is placed on the lower mold 23 that has been heated to a predetermined temperature Tc in advance, and is heated from the room temperature _TRM . The temperature of the lower mold 23 and the glass plate 17 increases as they are conveyed to PH2, PH3, and PH4, and reaches the target heating temperature T _PM which is the molding temperature before being conveyed to the molding stage 13 (PM).

On the forming stage 13 (PM), the glass plate 17 is formed while being held at a constant target heating temperature T _PM .

After molding, the temperature of the lower mold 23 and the glass plate 17A after molding is conveyed to C1 to C4 of the cooling stage 15 and gradually decreases. The glass plate 17A transported from C4 to the unloading unit 21 (ULD) shown in FIG. 15 is naturally cooled.

In each stage of the preheating stage 11 and the cooling stage 15, the temperature is controlled so that the lower mold 23 and the glass plates 17 and 17A are uniformly set at the respective stages. The larger the number of stages, the wider the range of temperature change. From the viewpoint of takt time, it is preferable to reduce the number of stages. The number of each stage is appropriately set according to the size of the glass plate to be processed, the processed shape, and the like. For example, when the size of the glass plate is large or when forming a complicated shape, it is preferable to increase the number of preheating stages 11 and cooling stages 15 in order to avoid a rapid temperature change.

FIG. 17 is a schematic view of a conventional molding apparatus as a reference example.
In the conventional molding apparatus, the glass plate 17 is entirely pressed by the lower die 131 and the upper die 135, and the heating temperature is set lower than the above-described molding temperature (target set temperature). Therefore, it is necessary to hold the glass plate 17 in the mold clamped state until the molding shape becomes stable. As a result, the molding time T _PM2 becomes longer than the molding time T _PM1 shown in FIG.

On the other hand, in the forming apparatus 200 of the present configuration shown in FIG. 15, the glass plate 17 is formed by combining the press forming in which only the outer circumference of the glass is contacted with the vacuum forming, the pressure forming, and the forming by gravity. The temperature can be set to a high temperature, and due to the synergistic effect of each molding, the glass plate comes into close contact with the molding surface of the molding die, and the molding shape stabilizes quickly. That is, springback of the glass plate is less likely to occur. As a result, only one molding stage 13 is required, the equipment cost can be reduced, and the throughput can be improved.

Also, by heating the temperature of the lower mold 23 to a predetermined temperature Tc in advance, the time required to reach the target set temperature can be further shortened and the takt time can be shortened.

FIG. 18 is a schematic view of a molding apparatus 300 showing another configuration example of the molding apparatus 200 shown in FIG.
The molding apparatus 300 having this configuration includes a plurality of molding lines including the preheating stage 11, the molding stage 13, and the cooling stage 15 shown in FIG. Although the molding apparatus 300 is shown in FIG. 18 as having a configuration including two lines, a first molding line 141 and a second molding line 143, it may have three or more lines.

The loading unit 19 of the first molding line 141 of the molding apparatus 300 is connected to the unloading unit 21 of the second molding line 143, and the unloading unit 21 of the first molding line 141 is the loading unit 19 of the second molding line 143. Connected to. The lower mold 23 of the first molding line 141 and the lower molds 23 of the second molding line 143 are commonly used and circulate in the respective lines.

According to this configuration, by returning the lower mold 23 conveyed to the unloading section 21 of one molding line to the loading section 19 of the other molding line, a decrease in mold temperature is suppressed, and the molding apparatus 300 operates. At times, the temperature is always maintained at or above the predetermined temperature Tc. Therefore, the temperature change width of the lower die 23 becomes small, and the temperature cycle load on the lower die 23 can be reduced. In addition, energy consumption for heating can be suppressed and running cost can be reduced.

Furthermore, compared with the configuration in which a plurality of molding lines are arranged in series, the installation space of the molding device 200 can be reduced, which also reduces the equipment cost.

<Details of molding process>
Next, preferable molding conditions in the molding process on the molding stage 13 will be described.
In the forming apparatus 100, 200, 300 having this configuration, it is preferable to form a glass plate based on the following forming conditions.

(Pressure condition)
In the press molding, the glass plate 17 is press-molded by applying different pressures to the respective regions of the glass central portion 121 and the glass outer peripheral portion 123 of the glass plate 17 shown in FIG. Specifically, when vacuum forming or pressure forming is not performed, the pressure Pct applied to the glass central portion 121 is 0 to 0.1 MPa, and the pressure Peg applied to the glass outer peripheral portion 123 is 0.1 to 10 MPa. Is preferred.

When vacuum forming or pressure forming is not performed, no pressure other than gravity acts on the glass central portion 121 of the glass plate 17. On the other hand, a pressure higher than that of the glass central portion 121 is applied to the glass outer peripheral portion 123 of the glass plate 17, and the glass plate 17 is fixed to the molding die. As a result, stable press molding without displacement of the glass plate 17 can be performed. Further, depending on the inclination direction and inclination angle of the projection 113 and the molding surface 111 (see FIGS. 7A and 7B) that come into contact with the glass plate 17, the direction of deformation of the glass plate 17 by press molding (convex downward or The amount of deformation can be determined.

When the glass plate 17 is formed by using both press forming and vacuum forming, the pressure Pct applied to the glass central portion 121 by pressing is 0 to 0.1 MPa, and the pressure Peg applied to the glass outer peripheral portion 123 is It is preferably 0.1 to 10 MPa. Then, the total pressure applied to the glass plate 17 by the press forming and the vacuum forming is such that the pressure Peg of the glass outer peripheral portion 123 is higher than the pressure Pct of the glass central portion 121 (Peg>Pct).

Further, when the glass plate 17 is formed by using press forming, vacuum forming and pressure forming together, the pressure Pct applied to the glass central portion 121 by pressing is 0 to 0.1 MPa, and the glass outer peripheral portion 123 is The applied pressure Peg is preferably 0.1 MPa to 10 MPa. The total pressure applied to the glass sheet 17 by press forming, vacuum forming and pressure forming is such that the pressure Peg of the glass outer peripheral portion 123 is higher than the pressure Pct of the glass central portion 121 (Peg>Pct). In this case, in addition to vacuum forming, pressure by pressure forming is also applied to the glass central portion 121, so that the pressure applied to the glass central portion is higher than in the case of only press forming and vacuum forming.

The above conditions may or may not include the bending effect due to self-weight forming before and after press forming.

(Temperature of glass plate)
When molding the glass plate 17 into a desired shape, the lower limit of the temperature during molding is preferably 400° C., more preferably Tg+40° C., further preferably Tg+80° C. The upper limit of the temperature during molding is preferably 750°C, more preferably 680°C, and even more preferably 650°C.

By setting the molding temperature within the above range, the molded shape of the glass plate 17 can be maintained in a short time, and the molding time can be shortened.

(Viscosity of glass plate)
When molding the glass plate 17 into the desired shape, the viscosity of the glass plate 17 during molding varies depending grades like of the glass plate 17 as described above, 1 × 10 -5 ^{Pa ·} s or less from the viewpoint of moldability Is preferred.

In particular, φ (=∫(P/ρ)dt, [P: in-plane pressure, ρ: viscosity]), which is an index of formability, is 1×10 ^−8.7 to 1×10 ^2.5 at the glass outer peripheral portion of the glass plate. , 1×10 ⁻¹² to 1×10 ^−0.5 eg at the center of the glass.

(Dimensional accuracy of glass plate)
According to the manufacturing apparatus and the molding method described above, a glass plate molded body having excellent shape accuracy can be obtained. As an evaluation index of the shape quality of the glass plate molded body, for example, an in-plane shape deviation compared with a design shape (design surface) can be mentioned.

The in-plane shape deviation is a curved surface approximation such that the absolute value of the distance from the design surface in the normal direction is the minimum in the surface when the normal is set along the design shape. The deviation value of the deviation amount in the normal direction between the surface approximated to the curved surface and the design surface is defined as the in-plane shape deviation.

The in-plane shape deviation of the glass sheet molded body obtained by the manufacturing apparatus and the molding method of this configuration is preferably 0.6 mm or less, more preferably 0.4 mm or less.

Table 1 collectively shows the molding conditions of the glass plate and the molding results.
Using a molding apparatus shown in FIG. 1, a glass plate (material: Dragon Trail (registered trademark)) having a size of 100×50 mm (thickness t=1.1 mm) is formed by only self-weight bending, full-press forming, and glass outer circumference. Molding was performed by only the edge press molding for pressing the part, and the molding method combining the press molding and the vacuum molding.

As for the shape of the glass plate, Test Examples 1 and 2 having a single radius of curvature shown in FIG. 19A, S-shaped Test Example 3 shown in FIG. 19B, and FIG. C-shaped test example 4 shown in C) and saddle-shaped test example 5 shown in FIG. The radius of curvature R of Test Example 1 is 2000 mm, and the radius of curvature R0 of Test Example 2 is 800 mm. The radius of curvature of the S-shaped test example 3 is 2000 mm for R1, 100 mm for R2, and 2000 mm for R3 in order from one end. J-shaped Test Example 4 has a shape in which a flat surface is connected to a curved surface having a radius of curvature R4 of 50 mm. The saddle-shaped test example 5 has a convex surface having a curvature radius R5 of 800 mm and a concave surface having a curvature radius R6 of 2000 mm in a direction orthogonal to the convex surface.

In Test Examples 1 to 4, the pressure for full-face press molding was set to 0.1 MPa, and in Test Example 5, the pressure for full-face press molding was both 0.1 MPa or less and pressure exceeding 0.1 MPa.
The molded product obtained by each molding method was evaluated with respect to the molding takt time, shape accuracy, and surface quality. The evaluation criteria are as shown below.・Tact time (time required for molding)
◎: Less than 30 s ◯: 30 s or more, less than 100 s △: 100 s or more, less than 200 s ▲: 200 s or more, less than 500 s ×: 501 s or more

・Shape accuracy (deviation from design shape)
◎: Less than 0.2 mm ○: 0.2 mm or more and less than 0.4 mm △: 0.4 mm or more and less than 0.6 mm ▲: 0.6 mm or more and less than 0.8 mm ×: 1.0 mm or more

・Surface quality (number of defects counted by image processing)
◎: 0 to 5 pieces ○: 6 to 10 pieces △: 11 to 50 pieces ▲: 51 to 100 pieces ×: 101 pieces or more

In the case of only self-weight bending forming, the takt time could not be shortened in any of the test examples.
In the case of full-press molding, when the pressure was set to 0.1 MPa or less, the entire surface of the glass plate was brought into contact with the molding die, so that the surface roughness of the glass surface after molding increased and the surface quality deteriorated. However, in Test Example 5, the surface quality was improved when a pressure exceeding 0.1 MPa was applied.

ㆍIn the case of edge press molding only with press, in the single curved test examples 1 and 2, the takt time and shape accuracy were good, and the surface quality was particularly excellent. However, in Test Examples 3, 4, and 5 in which the molding shape was relatively complicated, the takt time, the shape accuracy, and the surface quality were all NG.

On the other hand, when press forming and vacuum forming were combined by edge press forming, good results were obtained in Test Examples 1 to 4, and surface quality became NG in Test Example 5. That is, in the case of the saddle shape of Test Example 5, good results were obtained by applying a pressure of more than 0.1 MPa in full-face press molding.

The present invention is not limited to the above-described embodiments, and the configurations of the embodiments may be combined with each other, or may be modified and applied by those skilled in the art based on the description of the specification and well-known techniques. The invention is planned and is included in the scope of protection required.

As described above, the following items are disclosed in this specification.
(1) A method for forming a glass plate by heating the glass plate to form a desired shape,
Sandwiching the glass plate between a pair of molds,
By the forming die, the first pressurizing force of 0.1 MPa or less is not applied or applied to the glass central portion inside the outer peripheral edge of the glass plate in the mold clamping direction, and the outer peripheral edge of the glass central portion is used. A step of press-molding the glass plate by applying a second pressurizing force of 0.1 to 10 MPa different from the first pressurizing force to the outer peripheral portion of the glass plate up to the outer peripheral edge in the mold clamping direction. When,
A method for forming a glass plate having:
According to this glass plate forming method, the glass center portion of the glass plate and the glass outer peripheral portion are press-formed with different pressurizing forces, so that it is possible to suppress deterioration of the surface quality of the glass central portion having a low pressurizing force.

(2) There is a step of supplying a negative pressure between a first molding die and a glass plate which are arranged at the front in the mold clamping direction, and suck the glass plate to the first molding die (1). The method for forming a glass plate according to.
According to this glass plate forming method, the glass plate can be attracted to the first mold by negative pressure, and the glass plate can be formed into a desired shape more reliably and at high speed.

(3) A method of forming a glass plate by heating the glass plate to form a desired shape,
Sandwiching the glass plate between a pair of molds,
A pressure of 0.1 MPa or less is applied to the glass plate in the mold clamping direction from one of the pair of molding dies, and the outer peripheral edge of the glass plate starts from the outer periphery of the glass central portion inside the outer peripheral edge of the glass plate. The annular glass outer peripheral part between is sandwiched between the pair of molding dies, on the inner peripheral side of the glass outer peripheral part, the first molding die arranged ahead of the mold clamping direction, and the glass plate. The process of defining a space between
A step of supplying a negative pressure to the space defined between the glass plate and the first mold so that the glass plate is adsorbed to the first mold;
A method for forming a glass plate having:
According to this glass plate forming method, the operation of transferring the shape of the glass plate along the forming surface of the first forming die is substantially performed by vacuum suction. Therefore, high-quality molding can be performed without producing indentations or wrinkles on the plate surface of the glass plate due to the pressing of the second molding die. Further, since the desired shape is processed by vacuum suction, it is possible to perform molding with high accuracy and high quality even in a complicated shape which is difficult only by press molding.

(4) A suction hole is provided in at least a part of a portion having the maximum curvature of the molding surface of the first molding die that transfers the curved shape to the glass plate, and a negative pressure is applied from the suction hole to the space. The method for forming a glass plate according to (3), which comprises supplying.
According to this glass sheet forming method, the gap between the glass sheet and the forming surface gradually disappears toward the portion having the maximum curvature with the supply of the negative pressure. The molding surface and the molding surface are brought into close contact with each other without leaving a gap therebetween.

(5) The pair of molding dies is provided with a protrusion on one side and a concave molding surface corresponding to the protrusion on the other side.
The glass plate molding method according to (3) or (4), in which the curvature of the projection is smaller than the curvature of the molding surface at a position where the projection and the molding surface correspond.
According to this glass plate forming method, when the glass plate is sandwiched between the inclined surface of the protrusion and the inclined surface of the forming surface, the contact area with the glass plate is reduced, and the glass plate is easily deformed or moved. .. Therefore, the glass plate can be made to follow the molding surface faithfully and the shape accuracy can be improved.

(6) A first molding die in which a positive pressure is supplied between the second molding die arranged rearward in the mold clamping direction and the glass plate to arrange the glass plate forward in the mold clamping direction. The method for forming a glass plate according to any one of (1) to (5), further comprising:
According to this glass plate forming method, since the glass central portion of the glass plate is pressed against the first mold, the glass plate can be formed into a desired shape more reliably and at high speed.

(7) The glass plate is formed by heating the glass plate so that the viscosity of the glass plate is 5.94×10 ⁶ Pa·s to 5.22×10 ¹¹ Pa·s (1). The method for forming a glass plate according to any one of to (6).
According to this glass plate forming method, by making the glass plate have a viscosity excellent in formability, the glass plate is well fitted into the mold and can be quickly formed into a desired shape.

(8) The glass plate molded product after the glass plate is molded is the glass plate according to any one of (1) to (7), which has an in-plane shape deviation of 0.3 mm or less as compared with a designed shape. Molding method.
According to this glass plate forming method, a glass plate formed body having high shape accuracy can be obtained.

This application is based on the Japanese patent application (Japanese Patent Application No. 2019-21562) filed on February 8, 2019, the content of which is incorporated by reference in the present application.

11 Preheating Stage 13 Molding Stage 15 Cooling Stage 17, 17A Glass Plate 17a Outer Edge 23, 23A Lower Mold (First Mold)
25, 25A, 25B, 25C Upper mold (second mold)
27 chamber 35 upper heater (heating part for heating)
36 Lamp heater 41 Thermal diffusion plate 43 Lower heater (heating part for heating)
51, 53, 55 heat insulating frame 63A, 63B type transfer section 65 heat diffusion plate 67 upper heater (heat retention heating section)
73 Heat Diffusion Plate 75 Lower Heater (Heat Keeping Unit)
81 heat diffusion plate 83 upper heater (heating unit for temperature drop)
91 Heat Diffusion Plate 93 Lower Heater (heating part for cooling)
100 Molding Equipment 111, 111A Molding Surface 113, 113A Projection 113a Sloping Surface 115 Suction Hole 121 Glass Central Part 121a Central Part Outer 123 Glass Outer Part 125 Gas Outlet Hole 131 Lower Mold (First Mold)
135 Upper mold (second mold)
141 First molding line (molding line)
143 Second molding line (molding line)

Claims (8)

A method of forming a glass plate by heating the glass plate into a desired shape,
Sandwiching the glass plate between a pair of molds,
By the forming die, the first pressurizing force of 0.1 MPa or less is not applied or applied to the glass central portion inside the outer peripheral edge of the glass plate in the mold clamping direction, and the outer peripheral edge of the glass central portion is used. A step of press-molding the glass plate by applying a second pressurizing force of 0.1 to 10 MPa different from the first pressurizing force to the outer peripheral portion of the glass plate up to the outer peripheral edge in the mold clamping direction. When,
A method for forming a glass plate having: The method according to claim 1, further comprising a step of supplying a negative pressure between the first molding die and the glass plate, which are arranged at a front side of the mold clamping direction, so that the glass plate is adsorbed to the first molding die. Glass plate forming method. A method of forming a glass plate by heating the glass plate into a desired shape,
Sandwiching the glass plate between a pair of molds,
A pressure of 0.1 MPa or less is applied to the glass plate in the mold clamping direction from one of the pair of molding dies, and the outer peripheral edge of the glass plate starts from the outer periphery of the glass central portion inside the outer peripheral edge of the glass plate. The annular glass outer peripheral part between is sandwiched between the pair of molding dies, on the inner peripheral side of the glass outer peripheral part, the first molding die arranged ahead of the mold clamping direction, and the glass plate. The process of defining a space between
A step of supplying a negative pressure to the space defined between the glass plate and the first mold so that the glass plate is adsorbed to the first mold;
A method for forming a glass plate having: Of the molding surface of the first molding die that transfers the curved surface shape to the glass plate, a suction hole is provided in at least a part of a portion having the maximum curvature, and a negative pressure is supplied from the suction hole to the space. The method for forming a glass plate according to claim 3. The pair of molding dies, a projection portion on any one, the concave molding surface corresponding to the projection portion is provided on the other one,
The method for forming a glass sheet according to claim 3, wherein the curvature of the protrusion is smaller than the curvature of the forming surface at a position where the protruding portion and the forming surface correspond. Positive pressure is supplied between the second molding die arranged rearward in the mold clamping direction and the glass plate to press the glass plate against the first molding die arranged forward in the mold clamping direction. Process,
The method for forming a glass plate according to any one of claims 1 to 5, further comprising: The molding of the glass plate is performed by heating the glass plate so that the viscosity of the glass plate is 5.94×10 ⁶ Pa·s to 5.22×10 ¹¹ Pa·s. The method for forming a glass plate according to any one of claims 1. The glass plate molding method according to any one of claims 1 to 7, wherein the glass plate molded body after the glass plate is molded has an in-plane shape deviation of 0.3 mm or less compared with a designed shape.

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