CN113329977B

CN113329977B - Glass plate forming apparatus

Info

Publication number: CN113329977B
Application number: CN202080010213.6A
Authority: CN
Inventors: 井本祐司; 金杉谕
Original assignee: Asahi Glass Co Ltd
Current assignee: AGC Inc
Priority date: 2019-02-08
Filing date: 2020-02-04
Publication date: 2023-02-21
Anticipated expiration: 2040-02-04
Also published as: CN113329977A; TWI830867B; TW202039379A; JPWO2020162467A1; JP7463972B2; WO2020162467A1

Abstract

A glass sheet forming apparatus includes: a 1 st forming mold for supporting a glass sheet; at least one 2 nd forming die, matched mold to 1 st forming die; at least one preheating stage for heating the glass sheet supported by the 1 st forming mold; at least one forming station for forming a heated glass sheet between a 1 st forming die and a 2 nd forming die; at least one cooling station for slowly cooling the formed glass sheet; and a mold conveying section for conveying the 1 st molding mold in the order of the preheating stage, the molding stage, and the cooling stage. The 2 nd forming die and the 1 st forming die of the forming table are in contact with the glass sheet only at the glass peripheral portion.

Description

Glass plate forming apparatus

Technical Field

The present invention relates to a glass sheet forming apparatus.

Background

Various methods are used to manufacture a press-formed glass article by heating and softening a glass material accommodated in a forming die and pressing the softened glass material. For example, there has been proposed a forming apparatus in which a plate-shaped glass material is sequentially conveyed to heating, pressing, and cooling stations provided in a chamber, and a press-formed product is continuously formed by the respective stations (patent document 1).

In such a molding apparatus, the glass material is maintained at a heating temperature sufficient for processing the glass material by setting the molding die to a predetermined temperature during pressing. The glass material after molding is cooled, solidified, and finally cooled to a temperature of 200 ℃ or lower at which the molding die is not oxidized. As described above, the glass material becomes a press-molded product with high shape accuracy by accurately transferring the shape of the press mold at the time of pressing and maintaining the molded shape by cooling and solidifying.

Patent document 1: international publication No. 2013/103102

However, in the molding apparatus as described above, along with the complication and mass production of the molded shape of the glass material, there is room for improvement in various aspects such as productivity of the molded product and quality of the shape/surface property.

Disclosure of Invention

The invention aims to provide a glass plate forming device which can reduce equipment cost and form a formed product with high shape precision and high production even the formed product has a complex shape.

The present invention is constituted by the following structure.

A glass sheet forming apparatus for heating a glass sheet to form the glass sheet into a desired shape, the glass sheet forming apparatus comprising:

a first mold 1 having a molding surface with a curved surface at least in a part thereof, the molding surface supporting the glass sheet;

at least one 2 nd molding die clamped to the 1 st molding die;

at least one preheating stage for heating the glass sheet supported by the 1 st forming mold;

at least one molding stand in which the 2 nd molding die is disposed so as to face the 1 st molding die, and the heated glass sheet is molded between the 1 st molding die and the 2 nd molding die,

at least one cooling station for slowly cooling the formed glass sheet; and

a mold conveying section for conveying the 1 st molding mold in the order of the preheating stage, the molding stage, and the cooling stage,

the glass plate has: a glass central portion located inside the glass-shaped outer peripheral edge, and a glass outer peripheral portion located between the outer periphery of the glass central portion and the glass-shaped outer peripheral edge,

the 2 nd forming die and the 1 st forming die of the forming table are in contact with the glass sheet only at the glass peripheral portion.

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

Drawings

Fig. 1 is a schematic process diagram showing a procedure for forming a glass plate into a curved shape.

Fig. 2 is a schematic configuration diagram of a molding apparatus.

Fig. 3 is a cross-sectional view of a multiple lamp heater.

Fig. 4 is a schematic plan view of the III-III line section shown in fig. 2 as viewed from above.

Fig. 5 is a schematic explanatory view showing a case where the lower mold is conveyed in the conveying direction from the preheating stage toward the cooling stage.

Fig. 6 is an enlarged cross-sectional view of the forming station.

Fig. 7 (a) is a cross-sectional view of the upper mold, and (B) is a cross-sectional view of the lower mold including the molding surface.

Fig. 8 is a rear view of the upper die as viewed from the direction B of fig. 7 (a).

FIG. 9 is a top view of a glass plate.

Fig. 10A is a schematic process explanatory view showing a case where the lower mold and the upper mold shown in (a) and (B) of fig. 7 are brought into contact with each other in stages to perform the forming process on the glass plate.

Fig. 10B is a schematic process explanatory view showing a case where the lower mold and the upper mold shown in (a) and (B) of fig. 7 are brought into contact with each other in stages to perform the forming process on the glass plate.

Fig. 10C is a schematic process explanatory view showing a case where the lower mold and the upper mold shown in (a) and (B) of fig. 7 are brought into contact with each other in stages to perform the forming process on the glass plate.

Fig. 11 is an explanatory view of a schematic process in a case where a glass sheet is formed by the 2 nd forming method.

Fig. 12 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. 13 is a graph showing an example of temperature changes of the lower mold and the glass sheet in the preheating stage, the forming stage, and the cooling stage.

Fig. 14 is a schematic configuration diagram of a conventional molding apparatus as a reference example.

Fig. 15 is a schematic configuration diagram of a molding apparatus showing another configuration example of the molding apparatus shown in fig. 12.

Fig. 16 (a) is a schematic cross-sectional view showing the molded shapes of test examples 1 and 2, (B) is a schematic cross-sectional view showing the molded shape of test example 3, and (C) is a schematic cross-sectional view showing the molded shape of test example 4.

Detailed Description

Hereinafter, embodiments of the present invention will be described in detail.

Here, a specific example of a forming apparatus and a forming method for forming a glass plate into a shape having a curved surface shape at least in part will be described, but the present invention can also be modified in the configuration and order of the apparatus as appropriate depending on various manufacturing conditions such as a material to be used, a forming shape, and a size.

In the present specification, "to" indicating a numerical range is used in a sense of including numerical values before and after the range as a lower limit value and an upper limit value.

Outline of glass sheet Forming sequence

The glass sheet forming apparatus 100 is provided with a preheating stage 11, a forming stage 13, and a cooling stage 15 in this order, and further includes a loading section 19 for loading a glass sheet 17 before forming into the preheating stage 11, and an unloading section 21 for unloading a formed glass sheet 17A from the cooling stage 15.

The glass sheet 17 carried in is heated and softened in the preheating stage 11. The glass plate 17 heated and softened by the preheating stage 11 is press-formed into a desired shape on the forming stage 13. In the cooling stage 15, the glass sheet 17 formed on the forming stage 13 is slowly cooled to a temperature at which deformation can be suppressed.

The glass plate 17 is carried in and out from the loading section 19 and the unloading section 21 for each of the above-described stations. That is, the glass sheet 17 before molding is placed on the lower mold (mold 1) 23 in the mounting section 19. 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 forming table 13 together with the lower mold 23.

In the forming table 13, the glass sheet 17 is clamped between an upper mold (2 nd molding mold) 25 and a lower mold 23 mounted on the forming table 13. Thereby, the glass plate 17 is formed into a curved shape. After the molding, the upper mold 25 is separated from the lower mold 23, and the glass plate 17A left after the processing of the lower mold 23 is conveyed to the cooling stage 15 together with the lower mold 23.

In the cooling stage 15, the heated glass sheet 17A is slowly 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 forming apparatus of this configuration, in addition to press forming in which the glass sheet 17 softened by heating is pressed by the lower mold 23 and the upper mold 25, bending by the weight of the glass sheet (gravity bending forming), suction (vacuum suction) of the glass sheet to the forming surface of the forming mold, and pressure bonding (blank pressing) of the glass sheet to the forming surface of the forming mold are performed in combination depending on the purpose on the forming table 13. By selectively using such a plurality of pressure sources, curved surface forming with high shape accuracy can be performed. In the self-weight bending, the glass plate 17 is bent by its own weight by heating the glass plate 17 disposed on the lower mold 23, but controllability can be provided. For example, the bending start temperature and the press forming temperature due to the self-weight hardly diverge, and when the influence of the heating up to the press forming temperature on the self-weight bending is small, the self-weight bending is not applicable. On the other hand, when the deadweight forming time before and after the press is sufficient, the deadweight bending is applied because the shape after forming is affected by gravity. Thus, the deadweight bending can be controlled in accordance with the standby time and standby temperature before the press forming.

The above-described molding methods are the following molding methods.

(1) Press forming is a method of forming a glass sheet into a predetermined shape by placing the glass sheet between predetermined forming dies (a lower die and an upper die), applying a press load between the upper and lower forming dies in a state where the glass sheet is softened, and bending the glass sheet so that the glass sheet is bonded to the forming dies.

(2) The self-weight bending is a method of forming a glass plate into a predetermined shape by setting the glass plate on a predetermined forming mold, heating and softening the glass plate, and bending the glass plate by gravity to adhere the glass plate to the forming mold.

(3) Vacuum forming is performed by placing a glass sheet on a predetermined forming mold, for example, by placing a clamping forming mold on the glass sheet, and sealing the periphery of the glass sheet. Then, the closed space between the molding die and the glass plate is depressurized by a pump or the like, and a differential pressure is applied to the front surface and the back surface of the glass plate.

(4) In the press-and-blank molding method, a glass sheet is set on a predetermined molding die, for example, a clamping molding die is set on the glass sheet, and the periphery of the glass sheet is sealed. 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 surface and the back surface of the glass plate, thereby molding.

< glass Material to be shaped >

The glass plate as the molded body has a thickness of, for example, 0.5mm or more, preferably 0.7mm or more. The thickness of the glass plate is 5mm or less, preferably 3mm or less, and more preferably 2mm or less. Within this range, the final product can have a strength that is less likely to break.

As the glass composition constituting the glass plate, alkali-free glass, soda lime silicate glass, aluminosilicate glass, borosilicate glass, lithium aluminosilicate glass, and borosilicate glass can be used. In particular, the glass forming apparatus of the present configuration is excellent when aluminosilicate or aluminoborosilicate is used for the glass sheet. These glass sheets have a high young's modulus, a high coefficient of expansion, and high thermal stress is generated by heating of the glass sheets. Therefore, the deviation from the desired bent shape of the glass sheet becomes large, and when the glass sheet is further subjected to the strengthening treatment, the values of the compressive stress may become uneven. In the glass forming apparatus of the present configuration, the glass sheet has the above-described glass composition, and even when the glass sheet has a curved shape, the shape variation can be reduced, and the variation in the compressive stress can be suppressed.

Specific examples of the glass composition include a glass containing 50 to 80% of SiO in terms of a composition expressed by mol% based on oxides ₂ 0.1 to 25% of Al ₂ O ₃ 3 to 30% of Li ₂ O+Na ₂ O+K ₂ O, 0 to 25% MgO, 0 to 25% CaO and 0 to 5% ZrO ₂ However, the method is not particularly limited. More specifically, the following glass compositions can be mentioned. Herein, for example, "containing 0 to 25% of MgO" means that MgO may be contained in an amount of up to 25%, although not essential. The glass of (i) is contained in a soda-lime-silicate glass, and the glasses of (ii) and (iii) are contained in an aluminosilicate glass. (vi) the glass of (v) is contained in a lithium aluminosilicate glass.

(i) A composition comprising 63 to 73% of SiO in mol% based on the oxide ₂ 0.1 to 5.2 percent of Al ₂ O ₃ 10 to 16 percent of Na ₂ O, 0 to 1.5 percent of K ₂ O, 0 to 5% of Li ₂ O, 5 to 13 percent of MgO and 4 to 10 percent of CaO.

(ii) A composition expressed in mol% based on oxide, containing 50 to 74% of SiO ₂ 1 to 10% of Al ₂ O ₃ 6 to 14 percent of Na ₂ O, 3 to 11 percent of K ₂ O, 0 to 5% of Li ₂ O, 2-15% of MgO, 0-6% of CaO and 0-5% of ZrO ₂ And SiO ₂ And Al ₂ O ₃ The total content of (A) is 75% or less, na ₂ O and K ₂ A glass having a total content of O of 12 to 25% and a total content of MgO and CaO of 7 to 15%.

(iii) A composition containing 68 to 80% of SiO in mol% based on the oxide ₂ 4 to 10% of Al ₂ O ₃ 5 to 15 percent of Na ₂ O, 0 to 1% of K ₂ O、0～5% of Li ₂ O, 4-15% of MgO and 0-1% of ZrO ₂ The glass of (2).

(iv) A composition containing 67 to 75% of SiO in mol% based on the oxide ₂ 0 to 4% of Al ₂ O ₃ 7 to 15 percent of Na ₂ O, 1 to 9 percent of K ₂ O, 0 to 5% of Li ₂ O, 6 to 14% of MgO and 0 to 1.5% of ZrO ₂ And SiO ₂ And Al ₂ O ₃ The total content of (a) is 71-75%, and Na ₂ O and K ₂ A glass containing 12 to 20% by weight of O in total and less than 1% by weight when CaO is contained.

(v) A composition comprising 56 to 73% of SiO in mol% based on the oxide ₂ 10 to 24% of Al ₂ O ₃ 0 to 6 percent of B ₂ O ₃ 0 to 6% of P ₂ O ₅ 2 to 7% of Li ₂ O, 3-11% of Na ₂ O, 0 to 2% of K ₂ O, 0 to 8 percent of MgO, 0 to 2 percent of CaO, 0 to 5 percent of SrO, 0 to 5 percent of BaO, 0 to 5 percent of ZnO and 0 to 2 percent of TiO ₂ 0 to 4% of ZrO ₂ The glass of (2).

< Structure of Forming device >

Hereinafter, a structural example of the molding apparatus 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 III-III line section shown in fig. 2 as viewed from above.

In the following description, the same reference numerals are given to members and portions that perform the same function, and the description thereof may be omitted or simplified. The embodiments described in the drawings are schematic for clarity of explanation of the present configuration, and are not intended to be accurately expressed in terms of the size and scale of an actual 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 defined as a conveyance direction TD of a glass sheet, and a preheating stage 11, a forming stage 13, and a cooling stage 15 are arranged in this order from the upstream side in the conveyance direction TD. The preheating stage 11, the forming stage 13, and the cooling stage 15 are accommodated in the internal space of the chamber 27. The chamber 27 is purged with an inert gas such as nitrogen gas to reduce the gas concentration of the gas which adversely affects the glass forming.

The chamber 27 has: a carrying-in port 29 for carrying the glass plate and the lower mold 23 into the chamber 27; and a carrying-out port 31 for carrying out the formed glass plate and the lower mold 23. The loading unit 19 shown in fig. 1 is connected to the loading port 29, and the unloading unit 21 shown in fig. 1 (not shown) is connected to the unloading port 31 in the same manner. Further, the carrying-in port 29 and the carrying-out port 31 are provided with unshown shutters, and the shutters are closed except when the glass plate is carried in and out, whereby the atmosphere in the chamber 27 is kept constant. A plurality of openings 101 are formed in the cavity 27, and a support shaft 37 described later is inserted into each opening 101. The space between the support shaft 37 and the chamber 27 is sealed by a bellows structure not shown. In addition to the closed structure for closing the inert gas, the chamber 27 may be a semi-closed structure in which the inert gas is constantly supplied to make the inside of the chamber 27 positive in pressure.

In the preheating stage 11 shown in fig. 2, an upper heater (heating unit for raising temperature) 35 for heating the glass plate and the lower mold 23 to a desired heating temperature is disposed above the conveying surface of the glass plate. The upper heater 35 is preferably disposed to face the lower mold 23, and includes a plurality of lamp heaters 36 supported by a not-shown fixing frame as a heat source. As the lamp heater 36, for example, an infrared lamp heater is used. As the infrared lamp heater, for example, various known heaters such as a carbon filament lamp and a halogen lamp can be used, and any heating element can be used as long as it can perform radiation heating.

Fig. 3 is a cross-sectional view of the multiple lamp heater 36.

The lamp heater 36 has: a heating wire 36A that is energized to generate heat; and a tube material 36B made of quartz or the like surrounding the heating wire 36A. A ceramic coating 40 is formed on the inner or outer peripheral surface of the tube 36B so as to leave the irradiation window 38. The opening angle (center angle) θ of the irradiation window 38 with the heat-generating wire 36A as the center is determined by the distance Ld from the center of the lamp heater 36 to the lower mold 23 as the object to be heated and the arrangement pitch Lc of the lamp heater 36 so that the lower mold 23 is uniformly irradiated with the heat ray. Here, as an example, the opening angle θ is set to 60 °.

In addition, the heating region by the upper heater 35 (the region in which the lamp heaters 36 are arranged) is preferably wider than the outer edge of the horizontal surface of the lower mold 23, and in this case, the entire lower mold 23 can be uniformly heated.

Above the upper heater 35, a water-cooling plate 39 supported by the support shaft 37 is disposed. A reflective film is preferably provided on the surface of the water-cooling plate 39 facing the upper heater 35. A flow path of cooling water is formed in the water-cooling plate 39, and the cooling water supplied and discharged through the support shaft 37 circulates. The water cooling plate 39 suppresses unnecessary heating of the peripheral members other than the lower mold 23 and the glass plate by the upper heater 35.

A heat diffusion plate 41 is disposed below the lower die 23 with a gap. Further, a lower heater (heating unit for temperature increase) 43 is disposed below the heat diffusion plate 41. The heat diffusion plate 41 is made of a material having excellent thermal conductivity, and uniformly radiates and conducts heat generated by the lower heater 43 to the lower mold 23. As a material of the heat diffusion plate 41, for example, tungsten carbide, carbon, cemented carbide, copper, iron, stainless material, or the like can be used. The lower heater 43 may be a contact heating type stage heater, or the like, but may be a radiation heating type similar to the upper heater 35.

Further, a water cooling plate 47 is disposed below the lower heater 43. The water cooling plate 47 is supported by a support body 45 fixed to the lower portion of the chamber 27, and unnecessary heating of the peripheral components other than the heat diffusion plate 41 and the lower die 23 by the lower heater 43 is suppressed. The water cooling plate 47 has the same structure as the water cooling plate 39 described above, and supplies and discharges cooling water from the support body 45.

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

The heat insulating frame 51 is disposed 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 table on the side of the upper heater 35, the water-cooled 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 disposed in the stage.

For example, a heat insulating plate made of calcium silicate as a main material can be used as the heat insulating frame 51. In addition, for example, a metal plate made of stainless steel or the like 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 body covering an upper portion of the frame.

It is preferable that the

heat insulating frames

53 and 55 having the same configuration be disposed also in the forming table 13 and the cooling table 15. In order to improve the quality of the glass sheet obtained, it is particularly important to reduce the temperature variation of the glass sheet in each stage. For this reason, it is preferable that all of the respective units are provided with a heat insulating frame. This makes it possible to make the temperature distribution in the internal space covered with the

heat insulating frames

51, 53, and 55 uniform. Further, since the outside of the

heat insulating frames

51, 53, and 55 is surrounded by the chamber 27, the inflow and outflow of heat to and from the outside is less likely to occur in the

heat insulating frames

51, 53, and 55, and a more uniform temperature distribution is obtained. This improves the thermal efficiency, shortens the processing time in each stage, and reduces the temperature variation of the glass sheet in each stage.

As shown in fig. 4, lower molds 23 are disposed on the preheating stage 11, the forming stage 13, and the cooling stage 15, respectively. Each lower die 23 has a pair of die support bars 61 protruding outward from side surfaces 23a and 23b on both sides perpendicular to the conveying direction TD. The mold support rods 61 are supported by

mold conveying sections

63A and 63B disposed on both sides of the lower mold 23. The

mold conveying units

63A and 63B are not described in detail, but a plurality of lower molds 23 arranged along the respective stages are conveyed in the conveying direction TD by a conveying mechanism of a walking beam type as a conveying method.

Fig. 5 is a schematic explanatory view of a case where the lower mold 23 is conveyed in the conveying direction TD from the preheating stage 11 toward the cooling stage 15.

The

mold conveying sections

63A and 63B support the mold supporting rods 61 protruding from the plurality of lower molds 23, respectively, and convey the plurality of lower molds 23 simultaneously from the preheating stage 11 to the forming stage 13 and from the forming stage 13 to the cooling stage 15 by a stepping motion Liang Fangshi. The vertical displacement of the lower mold 23 during the conveyance is performed within a range that does not interfere with the fixed-side members such as the

heat insulating frames

51, 53, and 55 and the heat diffusion plate 41.

Next, the cooling stage 15 shown in fig. 2 will be explained.

A heat diffusion plate 65, an upper heater (temperature-lowering heating unit) 67 similar to the preheating stage 11, and a water cooling plate 59 are disposed in this order above the lower mold 23 of the cooling stage 15. The heat diffusion plate 65 has the same structure as the heat diffusion plate 41 described above. The water cooling plate 59 is supported by a support shaft 71 fixed to an upper portion of the chamber 27 and forming a flow path for the cooling water.

A heat diffusion plate 73, a lower heater (temperature lowering heating unit) 75, and a water cooling plate 77 are disposed below the lower mold 23 of the cooling stage 15, similarly to the preheating stage 11. The water cooling plate 77 is supported by a support body 79 fixed to the lower portion of the chamber 27, and suppresses unnecessary heating of the peripheral components other than the heat diffusion plate 73 and the lower die 23 by the lower heater 75. The water cooling plate 77 has the same structure as the water cooling plate 39 described above, and supplies and discharges cooling water from the support body 79.

Although 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 can be brought into close contact with each other, it is preferable to provide a gap to make the temperature distribution of the lower mold 23 more uniform.

Next, the forming table 13 shown in fig. 2 will be explained.

Fig. 6 is an enlarged sectional view of the forming table 13.

An upper mold 25, a heat diffusion plate 81, an upper heater (heat-retaining heating unit) 83, a heat insulating plate 85, and a water cooling plate 87 are disposed in this order above the lower mold 23 of the molding table 13.

The upper mold 25 is connected to a plunger, not shown, and is supported to be movable up and down between a molding position where it is clamped to the lower mold 23 and a retracted position above the molding position. The upper mold 25 is disposed at the retracted position except for the molding when the lower mold 23 is conveyed. Further, the upper mold 25 may be fixed inside the molding bed 13, and the lower mold 23 may be lifted to be clamped when the lower mold 23 is conveyed. In this case, the upper die moving mechanism can be omitted, and the facility cost can be reduced.

The water cooling plate 87 is supported by a support shaft 89 fixed to the upper portion of the chamber 27, and suppresses unnecessary heating of the peripheral components other than the upper die 25 and the heat diffusion plate 81 by the upper heater 83. The water cooling plate 87 has the same structure as the water cooling plate 39 described above, and supplies and discharges cooling water from the support shaft 89.

The heat insulating plate 85 can be made of a known heat insulating material such as ceramic, stainless steel, die steel, and high-speed steel (high-speed steel). When a metal-based material is used, it is preferable to perform coating treatment such as CrN, tiN, tiAlN, or the like on the surface. The surface of the heat shield plate 85 may have a rough surface structure. In this case, a small gap is formed between the water cooling plate 39 and the heat insulating plate, and a further excellent heat insulating effect can be obtained.

A heat diffusion plate 91, a lower heater (heat-retaining heating unit) 93, a heat insulating plate 85, and a water cooling plate 97 are disposed in this order below the lower die 23 of the forming table 13. The water cooling plate 97 is supported by a support 99 fixed to the lower portion of the chamber 27, and unnecessary heating of the peripheral components other than the heat diffusion plate 91 and the lower die 23 by the lower heater 93 is suppressed. The water cooling plate 97 has the same structure as the water cooling plate 39 described above, and supplies and discharges cooling water from the support 99.

The upper mold 25 of the forming table 13 is attached to a cylinder, not shown, which is driven in the vertical direction, and is supported so as to be movable in the vertical direction by the driving of the cylinder. As the cylinder, an air cylinder, a hydraulic cylinder, a servo cylinder using an electric servo motor or the like, or the like can be used.

The upper mold 25 of the forming table 13 is in surface contact with the heat diffusion plate 81 so that heat from the upper heater 83 is uniformly conducted to the upper mold 25. The lower mold 23 of the molding table 3 is in surface contact with the heat diffusion plate 91, so that heat from the lower heater 93 is uniformly conducted to the lower mold 23. Further, depending on molding conditions and the like, the upper mold 25 and the heat diffusion plate 81 and the lower mold and the heat diffusion plate 91 may be separated from each other.

Fig. 7 (a) is a sectional view of the upper mold 25, and (B) is a sectional view of the lower mold 23 including the molding surface 111. Fig. 8 is a rear view of the upper mold 25 as viewed from the direction B of fig. 7 (a).

As shown in fig. 7 (a) and 8, the upper die 25 has an annular projection 113. The projection 113 is provided on the upper die 25 corresponding to the outer edge of the molding surface 111 of the lower die 23 shown in fig. 7 (B) so as to project toward the lower die 23. The projection 113 has an inclined surface 113a whose projection amount gradually increases from the outer periphery of the upper die 25 toward the center. The molding surface 111 is formed in a shape conforming to the molding shape of the glass sheet.

As shown in fig. 7 (B), the lower mold 23 has a plurality of vacuum forming suction holes 115 opening on the forming surface 111. The suction hole 115 is connected to a suction source such as a suction pump not shown. The suction pump is driven to suck the gas in the space between the lower mold 23 and the glass sheet 17 at a predetermined time point, thereby bringing the glass sheet 17 into close contact with the molding surface 111.

The lower die 23 and the upper die 25 may be made of carbon, stainless steel, ceramics, cemented carbide, or the like. In particular, carbon is preferably used from the viewpoint of uniformizing the heat distribution.

The respective

upper heaters

35, 67, 83 and the respective

lower heaters

43, 75, 93 in the preheating stage 11, the forming stage 13, and the cooling stage 15 shown in fig. 2 are connected to a temperature control unit, not shown, and are set to respective independent set temperatures. The temperature control unit realizes heating, heat retention, and slow cooling processes in each station by control operations such as proportional control, PI control, and PID control.

The forming apparatus 100 described above has the glass sheet conveyance direction TD set to the horizontal direction, but may be set to a direction inclined from the horizontal direction, such as the vertical direction. In this case, although the lower mold 23 and the upper mold 25 may not be vertically arranged, the viscosity of the glass sheet is not excessively lowered by adjusting the heating temperature of the glass sheet, and thus the glass sheet can be molded between the lower mold 23 and the upper mold 25 while suppressing the influence of gravity.

< glass plate Forming sequence >

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

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 unit such as a robot arm not shown or by the hand of an operator.

The lower mold 23 of the loading unit 19 is conveyed to the preheating stage 11 by the

mold conveying units

63A and 63B shown in fig. 4 in a state where the glass plate 17 is placed thereon. It is preferable to heat the lower mold 23 to a temperature higher than the normal temperature before placing the glass plate 17, 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 ℃ or higher, and more preferably 500 ℃ or higher.

(preheating step)

In the preheating stage 11 shown in FIG. 2, the glass plate 17 on the lower mold 23 is heated by the upper heater 35 and the lower heater 43 until the target heating temperature (for example, 500 to 700 ℃ C.) is reached.

The temperature of the glass plate 17 suitable for press forming varies depending on the composition of the glass plate 17 itself, but if the temperature is too low, the glass plate 17 does not sufficiently soften. Therefore, the glass plate 17 is heated in the preheating stage 11 so that the glass transition temperature Tg is preferably equal to or higher than Tg, more preferably equal to or higher than Tg +40 ℃, and still more preferably equal to or higher than Tg +80 ℃. On the other hand, when the temperature of the glass plate 17 is too high, the glass plate 17 is softened excessively and becomes a state unsuitable for maintaining the shape. Therefore, the glass sheet 17 is heated in the preheating stage 11 so as to be preferably Tg +200 ℃ or less, more preferably Tg +150 ℃ or less, and still more preferably Tg +120 ℃ or less.

From the same viewpoint as described above, the glass sheet 17 is preferably heated on the preheating stage 11 so that the viscosity thereof becomes 5.22 × 10 ¹¹ Pa · s or more, more preferably 1.97X 10 ¹⁰ Pa · s or more, more preferably 1.81X 10 ⁹ Pa · s or more. Further, the glass plate 17 is heated on the preheating stage 11 so that the viscosity thereof is preferably 5.94X 10 ⁶ Pa · s or less, more preferably 4.16X 10 ⁷ Pa · s or less, more preferably 1.65X 10 ⁸ Pa · s or less.

From the viewpoint of the surface quality of the obtained glass sheet molded article, it is preferable to heat the glass sheet 17 uniformly on the preheating stage 11. That is, it is preferable to reduce the temperature variation of the glass sheet 17 during heating in the preheating stage 11. Specifically, the temperature variation of the glass sheet 17 during heating in the preheating stage 11 is preferably less than 30 ℃, more preferably less than 20 ℃, and still more preferably less than 10 ℃.

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 ℃, more preferably less than 25 ℃, and even more preferably less than 20 ℃.

(Molding Process)

The glass plate 17 heated to the target heating temperature is conveyed to the forming table 13 together with the lower mold 23. The heated glass sheet 17 is formed into a desired shape on the forming table 13 by applying an external force such as pressing.

In the forming table 13, the upper mold 25 disposed at the retracted position is lowered to sandwich the glass plate 17 between the lower mold 23, and the glass plate 17 is formed. Details of the forming process will be described later. In the forming table 13, the temperature is kept by the upper heater 83 and the lower heater 93 so that the temperature of the glass sheet 17 heated by the preheating table 11 is maintained constant.

The temperature of the glass sheet 17 in the forming table 13 is preferably controlled to be 20 ℃ or lower from the above-described heating temperature in the preheating table 11. In addition, from the viewpoint of the surface quality of the obtained glass sheet molded body, it is preferable to heat the glass sheet 17 uniformly on the molding table 13. Specifically, the temperature deviation of the glass sheet 17 during the forming on the forming table 13 is preferably within 20 ℃.

After the glass plate 17 is formed, the upper mold 25 is raised and returned to the retracted position. Then, the lower mold 23 is conveyed to the cooling stage 15 together with the formed glass plate 17A.

(Cooling Process)

In the cooling stage 15, the set temperatures of the upper heater 67 and the lower heater 75 are set to be lower than the target heating temperature, and the glass plate 17A and the lower mold 23 are slowly cooled. In the cooling stage 15, the glass plate 17 is slowly cooled until the shape of the heated and formed glass plate 17A becomes stable.

In the cooling stage 15, the glass plate 17A is slowly cooled while adjusting the heating temperature by the upper heater 67 and the lower heater 75. If the cooling rate in the cooling stage 15 is too high, the glass plate 17A is likely to be deteriorated and to have a temperature variation. Therefore, the cooling rate of the glass plate 17A in the cooling stage 15 is preferably set to 20 ℃ in 30 seconds, more preferably 30 ℃ and still more preferably 40 ℃. The temperature distribution of the glass plate 17A during cooling is preferably 30 ℃ or less, more preferably 25 ℃ or less, and further preferably 20 ℃ or less.

The glass plate 17A after the slow cooling is conveyed to the outside of the chamber 27, and then taken out through the unloading section 21 as shown in fig. 1. In the unloading section 21, the molded and slowly cooled glass plate 17A placed on the lower mold having a temperature of 300 ° or more, preferably 500 ° or more 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 by the hand of an operator.

< homogenization effect of temperature distribution >

The uniform temperature distribution of the

glass plates

17, 17A is achieved by synergistic effects such as the heat sealing effect of the

heat insulating frames

51, 53, 55, the high heat shielding effect of the chambers 27 outside the

heat insulating frames

51, 53, 55 to the outside, and the heat equalizing effect of the

heat diffusion plates

41, 65, 73, 81, 91 to the heaters. Further, radiation heating by the upper heater 35 of the preheating stage 11, heat conduction heating by the lower heater 43, heat conduction heating by the upper heater 83 and the lower heater 93 of the forming stage 13, and radiation heating by the upper heater 67 and the lower heater 75 via the

heat diffusion plates

65 and 73 in the case of cooling the stage are performed, whereby different heating systems are provided for the respective stages. Further, the upper heater and the lower heater of each stage can be heated at respective set temperatures independently, and thus, extremely precise temperature control can be performed.

By performing heating control independently for each heater on each of these stages, the temperature distribution of the

glass plates

17 and 17A can be made uniform at a high level. Further, fine adjustment according to the position is facilitated, and the heat treatment as designed can be accurately realized. Further, since the heated atmosphere is enclosed by the

heat insulating frames

51, 53, and 55 and the chamber 27, the outflow of heat to the outside is suppressed, and as a result, the responsiveness of the heating control and the temperature reduction control is improved, and a desired temperature can be reached uniformly and in a short time.

Further, since the

mold conveying sections

63A and 63B convey the lower mold 23 by the steps Liang Fangshi, the inter-table movement speed is increased. This suppresses heat loss due to heat dissipation between stages, and also achieves uniformity of temperature distribution.

The

heat diffusion plates

41, 65, 73, 81, and 91 can be omitted depending on molding conditions, but the provision of the heat diffusion plates suppresses temperature variation of the

glass plates

17 and 17A in the respective stages.

< details of the Forming Process >

Next, a method of molding the glass sheet 17 in the molding table 13 and a structure of a molding die will be described in detail.

First, the shape of the glass sheet 17 for forming is defined.

Fig. 9 is a plan view of the glass plate 17.

The glass plate 17 has a glass central portion 121 located inside the outer peripheral edge 17a of the glass shape, and a glass outer peripheral portion 123 extending from the central portion outer periphery 121a of the glass central portion 121 to the outer peripheral edge 17a. In fig. 9, the outer peripheral portion 123 is hatched. In the forming step, at least a part of the glass central portion 121 is formed into a curved surface shape.

(1 st Forming method)

Fig. 10A, 10B, and 10C are schematic process explanatory views showing a case where the glass sheet 17 is formed by bringing the lower mold 23 and the upper mold 25 shown in fig. 7 (a) and (B) into contact with each other in stages.

As shown in fig. 10A, the glass sheet 17 is placed on the molding surface 111 of the lower mold 23 in a state where the outer peripheral edge 17a of the glass sheet 17 is in contact therewith. 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 mold 25 has a portion in contact with the glass plate 17 and a portion not in contact with the glass plate, and only the inclined surface 113a of the protrusion 113 is in contact with the glass outer peripheral portion 123 of the glass plate 17. Then, as shown in fig. 10B, 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, even if the upper mold 25 only annularly contacts the glass plate 17, the glass plate 17 can be deformed toward the lower mold 23. The glass plate 17 is also deflected downward by its own weight and deformed to follow the molding surface 111 of the lower mold 23.

Next, as shown in fig. 10C, the glass sheet 17 is vacuum-sucked to the forming surface 111 by supplying a negative pressure from the suction holes 115. Thereby, the glass plate 17 is brought into close contact with the molding surface 111, and the curved surface shape of the molding surface 111 is transferred to the glass plate 17. This makes it possible to reliably bring a portion that is not easily brought into close contact with the glass plate 17 and the molding surface 111 only by press molding, and to easily mold even a complicated shape that is difficult to be brought into close contact with only by press molding.

The positions, the number, the sizes, and the like of the suction holes 115 are not particularly limited, and the suction holes 115 are preferably formed in portions of the molding surface 111 where the glass sheet 17 is not easily brought into close contact only by press molding. The size of the suction holes 115 is preferably adjusted to such an extent that no trace of the suction holes 115 remains in the glass plate 17 or that even if the trace remains, the trace is not conspicuous.

In general, in press forming of a glass sheet, the entire surface of the glass sheet is sandwiched and formed in contact with a forming mold. Therefore, the glass plate is molded at a relatively low temperature in order to ensure the surface quality of the resulting glass plate molded product. Therefore, a relatively long time is required to deform the glass plate into a desired shape. Therefore, when a complicated shape is formed, it is difficult to form the molded article in a low temperature range where surface quality can be ensured. On the other hand, when the lower mold 23 and the upper mold 25 configured as described above are used for molding, the upper mold 25 does not contact the glass central portion 121 of the glass sheet 17. Therefore, even when the glass sheet is molded at a relatively high temperature, adverse effects such as surface roughening due to contact with the molding die do not occur in the glass central portion 121, and a glass sheet molded article having excellent surface quality can be obtained. In this way, the molding table 13 of the present configuration can perform molding at a relatively high temperature, and thus can complete molding in a short time. That is, by using the above-described press mold, a glass sheet molded product having excellent surface quality can be obtained in a short time.

The lower mold 23 and the upper mold 25 of the present configuration are molds for obtaining a glass sheet molded article 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 not limited to the shapes illustrated in the drawings. The shapes of the lower mold 23 and the upper mold 25 can be changed as appropriate according to the target shape of the molding.

The lower die 23 and the upper die 25 of the present configuration realize combined forming of press forming, vacuum forming, and gravity-based bending forming, but can be formed only by press forming other than vacuum forming and by weight-based forming depending on the material, forming conditions, and the like.

(2 nd Forming method)

In the 1 st forming method, three types of forming, i.e., press forming, vacuum forming, and bending by gravity, are combined, but in the 2 nd forming method, press forming is further combined.

Fig. 11 is an explanatory view of a schematic process in a case where the glass plate 17 is formed by the 2 nd forming method. The molding die in this case has the same structure as the molding die of the molding method 1 except that the gas ejection holes 125 for the void molding are formed inside the annular protrusion 113 of the upper die 25A.

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

When the lower mold 23 and the upper mold 25A having the above-described configuration are used and press-formed and press-blank-formed at the same time, the gas is discharged from the gas discharge hole 125 after the protrusion 113 of the upper mold 25A is brought into contact with the glass outer peripheral portion 123 of the glass plate 17. Then, the glass plate 17 is pressed against the molding surface 111 of the lower mold 23. That is, since the projection 113 is formed annularly and the contact with the glass plate 17 is also formed annularly, the closed space 129 is formed between the molding surface 111 of the lower mold 23 and the glass plate 17. The gas is supplied to the closed space 129, and the pressure in the closed space 129 is made positive. Whereby the glass sheet 17 is pressed against the forming surface 111.

Further, by simultaneously performing the vacuum forming and the gravity-based forming together with the above-described press forming, the glass sheet 17 can be more quickly and reliably made to follow the forming surface 111, and the time required until the forming is completed can be shortened. In this way, by combining at least one of vacuum forming, pressure-air forming, and bending by gravity with press forming, it is possible to easily form a complicated shape, and it is possible to further shorten the forming time.

The vacuum forming and the pressure-air forming can be performed at any time during the press forming, and the order of execution may be press forming, vacuum forming, and pressure-air forming, or may be press forming, pressure-air forming, and vacuum forming. By performing press forming prior to vacuum forming and blank pressing, the glass sheet 17 can be more reliably positioned with respect to the forming surface 111.

Further, by performing the molding simultaneously, the adhesion between the glass plate 17 and the molding surface 111 can be further improved, and the processing of the shape in which wrinkles are easily generated in the glass plate 17 becomes easy.

< construction example of other Molding apparatus >

The glass-pane forming apparatus 100 may be configured to include a plurality of preheating stages 11 and a plurality of cooling stages 15.

Fig. 12 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 stage 11 is provided at four places (PH 1 to PH 4) along the conveying direction TD of the lower mold 23, and the cooling stage 15 is provided at four places (C1 to C4) along the conveying direction TD of the lower mold 23. The forming table 13 is provided at one position (PM 1) between the preheating table 11 and the cooling table 15.

The heating temperature of the preheating stage 11 is set to be increased stepwise along the conveyance direction TD from PH1 to PH 4. Thus, the lower mold 23 and the glass plate 17 are gradually heated up as they are conveyed in the conveying direction TD, and are heated to reach the target heating temperature, which is the molding temperature.

The heating temperature of C1 to C4 of the cooling stage 15 is set to be gradually lower along the conveyance direction TD. Thus, the lower mold 23 and the glass plate 17 are gradually cooled down from the target heating temperature as they are conveyed in the conveying direction TD.

Fig. 13 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 forming stage 13, and the cooling stage 15.

The glass plate 17 of PH1 supplied from the loading part 19 (LD) shown in FIG. 12 to the preheating stage 11 is placed on the lower mold 23 heated in advance to a predetermined temperature Tc and is cooled from room temperature T _RM Heating is started. The lower mold 23 and the glass sheet 17 are raised in temperature as they are conveyed to PH2, PH3, and PH4, and reach a target heating temperature T as a forming temperature before being conveyed to the forming table 13 (PM) _PM 。

The forming table 13 (PM) is heated at a target heating temperature T _PM The constant temperature of (2) keeps the glass plate 17 being shaped while it is being formed.

After the molding, the temperature of the lower mold 23 and the molded glass plate 17A gradually decreases while being conveyed to C1 to C4 of the cooling stage 15. The glass plate 17A conveyed from C4 to the unloading unit 21 (ULD) shown in fig. 12 is naturally cooled.

In each of the preheating stage 11 and the cooling stage 15, temperature control is performed so that the lower mold 23 and the

glass plates

17 and 17A are uniformly set at a predetermined temperature. The larger the number of stages, the larger the range of temperature change can be. In addition, from the viewpoint of the production interval time, it is preferable to reduce the number of stages. The number of the respective stations is appropriately set in accordance with the size, the processing shape, and the like of the glass plate to be processed. For example, when the glass sheet is large in size and when a complicated shape is formed, it is preferable to increase the number of the preheating stages 11 and the cooling stages 15 in order to avoid a rapid temperature change.

Fig. 14 is a schematic diagram of a conventional molding apparatus as a reference example.

The conventional molding apparatus is configured to press the entire surface of the glass plate 17 with the lower mold 131 and the upper mold 135, and the heating temperature is set to be lower than the above-described molding temperature (target set temperature). Therefore, the glass plate 17 needs to be held in a clamped state until the molded shape is stabilized. As a result, the molding time T _PM2 Becomes longer than the forming time T shown in FIG. 13 _PM1 。

On the other hand, in the forming apparatus 200 of the present configuration shown in fig. 12, since the glass sheet 17 is formed by combining press forming, vacuum forming, press forming, and gravity-based forming which are only in contact with the outer periphery of the glass, the heating temperature can be set to a higher temperature than in the conventional art, and the glass sheet can be brought into close contact with the forming surface of the forming mold due to the synergistic effect of the respective forming processes, so that the formed shape is quickly stabilized. That is, the glass sheet is less likely to rebound. This only requires one molding table 13, and can reduce equipment cost and improve throughput.

Further, by heating the temperature of the lower mold 23 to the predetermined temperature Tc in advance, the time to reach the target set temperature can be further shortened, and the production interval time can be shortened.

FIG. 15 is a schematic view of a molding apparatus 300 showing another configuration example of the molding apparatus 200 shown in FIG. 12.

The molding apparatus 300 of this configuration includes a plurality of molding lines each having a preheating stage 11, a molding stage 13, and a cooling stage 15 shown in fig. 12. The molding apparatus 300 has a configuration in which two lines, i.e., the 1 st molding line 141 and the 2 nd molding line 143, are provided in fig. 15, but three or more lines may be provided.

The loading section 19 of the 1 st forming line 141 of the forming apparatus 300 is connected to the unloading section 21 of the 2 nd forming line 143, and the unloading section 21 of the 1 st forming line 141 is connected to the loading section 19 of the 2 nd forming line 143. Then, the lower die 23 of the 1 st forming line 141 and the lower dies 23 of the 2 nd forming line 143 are used in common, and circulated in the respective lines.

According to this configuration, the lower mold 23 conveyed to the unloading section 21 of one molding line is returned to the loading section 19 of the other molding line, thereby suppressing the drop in the mold temperature and maintaining the temperature at or above the predetermined temperature Tc during the operation of the molding apparatus 300. This reduces the temperature change width of the lower mold 23, and reduces the temperature cycle load on the lower mold 23. In addition, energy consumption for heating can be suppressed, and running cost can be reduced.

Further, the installation space of the molding apparatus 200 can be reduced as compared with a configuration in which a plurality of molding lines are arranged in series, and thus the facility cost can also be reduced.

< details of the Forming Process >

Next, preferred molding conditions in the molding step of the molding table 13 will be described.

In the forming

apparatuses

100, 200, and 300 having the present configuration, it is preferable to form a glass sheet based on the forming conditions shown below.

(pressure conditions)

In the press forming, different pressures are applied to respective regions of the glass central portion 121 and the glass peripheral portion 123 of the glass plate 17 shown in fig. 9, and the glass plate 17 is press-formed. Specifically, when vacuum forming or pressure forming is not performed, it is preferable that the pressure Pct applied to the glass central portion 121 be 0 to 0.1MPa and the pressure Peg applied to the glass outer peripheral portion 123 be 0.1 to 10MPa.

When the vacuum forming or the press forming is not performed, a pressure other than the gravity is not applied to the glass central portion 121 of the glass plate 17. On the other hand, the glass peripheral portion 123 of the glass plate 17 is pressed higher than the glass central portion 121, and the glass plate 17 is fixed to the molding die. This enables stable press forming without positional displacement of the glass plate 17. The deformation direction (downward projection or upward projection) and the deformation amount of the glass sheet 17 formed by press forming can be determined according to the inclination direction and the inclination angle of the projection 113 and the forming surface 111 (see fig. 7a and B) which are in contact with the glass sheet 17.

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

When the glass plate 17 is formed by press forming, vacuum forming, and pressure forming in combination, it is preferable that the pressure Pct applied to the glass central portion 121 by the press is 0 to 0.1MPa, and the pressure Peg applied to the glass outer peripheral portion 123 is 0.1 to 10MPa. Then, the total of the pressures applied to the glass plate 17 by the press forming, the vacuum forming, and the pressure-air forming is set to a pressure Peg at the glass outer peripheral portion 123 higher than the pressure Pct at the glass central portion 121 (Peg > Pct). In this case, since the pressure by the press-and-air forming is applied to the glass central portion 121 in addition to the vacuum forming, the pressure applied to the glass central portion is larger than that in the case of only the press forming and the vacuum forming.

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

(temperature of glass plate)

When the glass plate 17 is formed into a desired shape, the lower limit of the temperature at the time of forming is preferably 400 ℃, more preferably Tg +40 ℃, and still more preferably Tg +80 ℃. The upper limit of the temperature during molding is preferably 750 ℃, more preferably 680 ℃, and still more preferably 650 ℃.

By setting the forming temperature in the above range, the formed shape of the glass plate 17 can be maintained for a short time, and the forming time can be shortened.

(tackiness of glass plate)

When the glass plate 17 is formed into a desired shape, the viscosity of the glass plate 17 at the time of forming differs depending on the type of the material of the glass plate 17, but is preferably 1 × 10 from the viewpoint of formability ^-5 Pa · s or less.

In particular, it is an index of formability

(=: [ P/ρ ] dt, [ P: in-plane pressure, [ ρ: viscosity: [ P ] ]]) Preferably, the thickness of the glass plate is 1X 10 at the outer periphery of the glass ^-8.7 ～1×10 ^2.5 1X 10 in the center of the glass ^-12 ～1×10 ^-0.5 eg。

(dimensional accuracy of glass plate)

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

The in-plane shape deviation is defined as a deviation of the in-plane shape of a surface obtained by approximating the shape of the glass sheet molding to a curved surface so that the absolute value of the distance from the design surface in the normal direction is the minimum in the plane when the normal is set to the design shape, and the deviation of the deviation amount in the normal direction between the surface obtained by approximating the curved surface and the design surface.

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

Examples

Table 1 summarizes the conditions and results of forming the glass sheets.

A glass plate (material: dragonttrail (registered trademark)) having a size of 100 × 50mm (thickness t =1.1 mm) was formed by using the forming apparatus shown in fig. 1, by using press forming such as only bending by its own weight, press forming such as only press forming of the entire surface, press forming such as only press forming of the edge of the outer peripheral portion of the press glass, and forming such as forming by combining press forming and vacuum forming.

The glass plate was molded in the shapes of test examples 1 and 2 having a single radius of curvature shown in fig. 16 (a), test example 3 having an S-shape shown in fig. 16 (B), and test example 4 having a J-shape shown in fig. 16 (C). The radius of curvature R in test example 1 was 2000mm, and the radius of curvature R in test example 2 was 800mm. In addition, in test example 3 of S-shape, R1, R2, and R3 were 2000mm, 100mm, and 2000mm, respectively, in this order from one end portion. The J-shaped test example 4 has a shape in which a curved surface having a curvature radius R of 50mm is connected from a flat shape.

The molded bodies obtained by the respective molding methods were evaluated for production interval time, shape accuracy, and surface quality of molding. The evaluation criteria are as follows.

Production interval time (time required for forming)

Very good: less than 30s

O: 30s or more and less than 100s

And (delta): more than 100s and less than 200s

A tangle-solidup: more than 200s and less than 500s

X: over 501s

Shape accuracy (deviation from design shape)

Very good: less than 0.2mm

O: 0.2mm or more and less than 0.4mm

And (delta): 0.4mm or more and less than 0.6mm

A tangle-solidup: more than 0.6mm and less than 0.8mm

X: 1.0mm or more

Surface quality (number of defects counted based on image processing)

Very good: 0 to 5

O: 6 to 10

And (delta): 11 to 50

A tangle-solidup: 51 to 100

X: more than 101

[ Table 1]

In the case of only the dead-weight bending, neither of the test examples was able to accelerate the production interval time.

In the case of the full-surface press molding, the full surface of the glass sheet comes into contact with the molding die, so that the surface roughness of the glass surface after molding is increased, and the surface quality is degraded.

In the case of edge press forming, test examples 1 and 2 in the single curve form gave results of good production interval time and shape accuracy, and particularly excellent surface quality. However, in test examples 3 and 4 in which the molded shape became relatively complicated, the production interval time, the shape accuracy, and the surface quality were not satisfactory (NG).

On the other hand, when the press forming and the vacuum forming were combined in the edge press forming, good results were obtained in all of test examples 1 to 4.

As described above, the present invention is not limited to the above-described embodiments, and embodiments modified and applied by those skilled in the art based on the combination of the respective configurations of the embodiments, the description of the specification, and known techniques are also intended to be included in the scope of the present invention.

As described above, the present specification discloses the following matters.

(1) A glass sheet forming apparatus for heating a glass sheet to form the glass sheet into a desired shape, the glass sheet forming apparatus comprising:

a first forming mold 1 having a forming surface with a curved surface at least in a part thereof, the forming surface supporting the glass sheet;

at least one 2 nd molding die clamped to the 1 st molding die,

at least one forming table in which the 2 nd forming die is arranged so as to face the 1 st forming die, and the heated glass sheet is formed between the 1 st forming die and the 2 nd forming die;

at least one cooling station for slowly cooling the formed glass sheet; and

the glass plate has: a glass central portion located inside the outer peripheral edge of the glass shape, and a glass peripheral portion located between the outer periphery of the glass central portion and the outer peripheral edge of the glass shape,

According to this glass sheet molding apparatus, since the glass sheet is pressed only at the outer peripheral portion of the glass between the 1 st molding die and the 2 nd molding die, the central portion of the glass on the 2 nd molding die side does not contact the die surface. Therefore, the surface quality of the central portion of the glass can be improved and the glass can be molded, and the molding can be performed at a higher temperature than the press molding in which the molding die is in contact with the entire surface of the glass. Thus, the molding can be completed in a short time, and the production interval time can be shortened.

(2) The apparatus for forming a glass sheet according to the item (1), wherein the 1 st forming mold has suction holes for vacuum forming, which are opened to the forming surface.

According to the glass sheet forming apparatus, the glass sheet can be forcibly brought into close contact with the forming surface by suction from the suction holes, and the shape transfer of the forming surface to the glass sheet can be performed more reliably and at a high speed.

(3) The apparatus for forming a glass sheet according to (1) or (2), wherein the 2 nd forming mold has: an annular protrusion portion protruding toward the first molding die 1; and a gas ejection hole disposed inside the annular projection, for ejecting gas for pressure forming.

According to the glass sheet forming apparatus, the glass sheet can be forcibly brought into close contact with the forming surface by the supply of the gas pressure from the gas ejection holes, and the shape transfer of the forming surface to the glass sheet can be performed more reliably and at a high speed.

(4) The apparatus for forming a glass sheet according to any one of (1) to (3), wherein the 1 st forming mold is disposed below the 2 nd forming mold in the vertical direction.

According to the glass sheet forming apparatus, the softened glass sheet can be brought into close contact with the forming surface by its own weight.

(5) The glass sheet forming apparatus according to any one of (1) to (4), comprising:

a heating section for temperature increase provided in the preheating stage, the heating section heating the first molding die 1 and the glass sheet to a desired heating temperature;

a heat-retaining heating unit provided in the molding table, for maintaining the temperature of the 2 nd molding die and the 1 st molding die at the heating temperature and maintaining the glass sheet at a desired molding temperature; and

and a cooling heating unit provided in the cooling stage, the cooling heating unit heating the 1 st molding die and the glass plate to a temperature lower than the heating temperature while heating the 1 st molding die and the glass plate.

According to the glass sheet forming apparatus, the temperature of each heating unit can be set with higher accuracy.

(6) The apparatus for forming a glass sheet according to (5), wherein at least one of the heating unit for raising the temperature, the heating unit for keeping the temperature, and the heating unit for lowering the temperature is a lamp heater for a plurality of radiant heating as a heat source.

According to the glass plate forming apparatus, the heating control can be performed finely by driving the plurality of lamp heaters, and the glass plate and the forming mold can be controlled to have uniform temperature distribution by heating with radiant heat.

(7) The apparatus for forming a glass sheet according to (5), wherein at least one of the heating unit for raising the temperature, the heating unit for keeping the temperature, and the heating unit for lowering the temperature includes a plurality of stage heaters for contact heating as heat sources.

According to the glass sheet forming apparatus, the use of the stage heater for contact heating enables efficient and uniform temperature control.

(8) The apparatus for forming a glass sheet according to the item (7), wherein at least one of the heat-retaining heating unit and the temperature-lowering heating unit is provided with a heat diffusion plate between the stage heater and the 1 st forming mold.

According to this glass sheet molding apparatus, since the 1 st molding die is heated via the thermal diffusion plate, the heat from the heater can be uniformly diffused in the plate surface of the thermal diffusion plate, and the temperature of the glass sheet and the molding die facing the thermal diffusion plate can be made more uniform.

(9) The apparatus for forming a glass sheet according to any one of (5) to (7), wherein the cooling heating section is disposed at a position not directly contacting the first forming mold 1 in the cooling stage.

According to this glass sheet molding apparatus, the temperature control is performed only by radiant heat without directly contacting the cooling heating section with the 1 st molding die, and thus more accurate temperature control can be performed.

(10) The apparatus for forming a glass sheet according to any one of (1) to (9), wherein at least one of the preheating stage, the forming stage, and the cooling stage is provided with a heat insulating frame body that surrounds the outer periphery of each stage and covers a side of the glass sheet supported by the first forming mold 1 disposed inside the stage.

According to the glass plate forming apparatus, the temperature is maintained at a uniform temperature in the region surrounded by the heat insulating frame. In addition, since the inflow and outflow of heat into and out of the heat insulating frame are suppressed, the responsiveness of temperature control by heating is improved.

(11) The apparatus for forming a glass sheet according to item (10), wherein the heat insulating frame is disposed on all of the preheating stage, the forming stage, and the cooling stage,

the apparatus includes a chamber having an internal space for accommodating the preheating stage, the forming stage, and the cooling stage.

According to the glass sheet forming apparatus, temperature control in each station can be accurately performed, and the quality of a formed glass sheet can be improved. In addition, the chamber further suppresses the outflow and inflow of heat from each heat insulating frame, and the temperature in the region surrounded by the heat insulating frame can be made more uniform.

(12) The apparatus for forming a glass sheet according to (11), wherein an inner space of the chamber is filled with an inert gas.

According to the glass sheet forming apparatus, the gas concentration of the gas which adversely affects the glass sheet during forming can be reduced, and the glass sheet can be prevented from being deteriorated.

(13) The apparatus for forming a glass sheet according to any one of (1) to (12), wherein the 1 st forming mold and the 2 nd forming mold are made of carbon.

According to the glass sheet forming apparatus, the mold is a carbon mold, so that the weight of the mold can be reduced and the service life of the mold can be prolonged.

(14) The apparatus for forming a glass sheet according to any one of (1) to (13), wherein a plurality of the preheating stages are arranged along a conveying direction of the 1 st forming mold, and a heating temperature of the preheating stages is set to be higher stepwise along the conveying direction.

According to this glass sheet forming apparatus, since heating can be advanced stepwise while each of the preheating stages is in a uniform temperature distribution state, temperature unevenness during heating can be reduced as compared with a case where heating is performed to a desired target heating temperature in one preheating stage.

(15) The apparatus for forming a glass sheet according to any one of (1) to (14), wherein a plurality of the cooling tables are arranged along a conveying direction of the 1 st forming mold, and a heating temperature of the cooling tables is set to be gradually lower along the conveying direction.

According to the forming apparatus for a glass sheet, since the glass sheet can be cooled in stages while the cooling stages are set to have a uniform temperature distribution, temperature unevenness during cooling can be reduced as compared with a case where the glass sheet is cooled to a desired temperature on one cooling stage.

(16) The apparatus for forming a glass sheet according to any one of (1) to (15), wherein a plurality of the 1 st forming molds are arranged along the preheating stage, the forming stage, and the cooling stage,

the mold transfer unit simultaneously carries the 1 st molding dies into and out of the respective preheating stage, molding stage, and cooling stage.

According to the glass sheet molding apparatus, since a plurality of the first molding dies and the glass sheet can be conveyed at a time, molding efficiency can be improved and throughput can be improved.

(17) The apparatus for forming a glass sheet as set forth in (16), wherein a conveyance system of the 1 st forming mold of the mold conveyance section is a walking beam system.

According to the forming apparatus for a glass sheet, the first forming mold 1 can be stably conveyed without complicating the conveying mechanism.

(18) The glass sheet forming apparatus according to (16) or (17), comprising a plurality of forming lines including the preheating stage, the forming stage, and the cooling stage,

each of the forming wires further includes: a loading section for loading the first molding die 1 and the glass sheet before molding into the preheating stage; and an unloading section for unloading the first molding die 1 and the molded glass sheet from the cooling stage,

the 1 st forming die is cyclically used in a plurality of the forming lines by connecting the loading section of any one of the forming lines and the unloading section of another forming line different from the forming line.

According to the glass sheet molding apparatus, the 1 st molding die is circulated in common in the plurality of molding lines, so that the facility cost can be reduced, and the temperature of the 1 st molding die can be prevented from being greatly lowered from the target heating temperature. This can reduce the thermal stress of the 1 st molding die. In addition, the increase of heating energy is suppressed, and the running cost can be reduced.

(19) The apparatus for forming a glass sheet according to (18), wherein the temperature of the 1 st forming mold at the time of transferring the glass sheet over the 1 st forming mold in the loading section and the unloading section is 300 ℃ or higher.

According to the forming apparatus for a glass sheet, since the glass sheet is transferred at a high temperature of 300 ℃ or higher, the heating time and cooling time of the glass sheet can be shortened as compared with the case where the glass sheet is transferred at a temperature close to the normal temperature, and the production interval time of the forming can be further shortened.

The present application was made based on japanese patent application (japanese patent application 2019-21561) filed on 8/2/2019, the contents of which are incorporated herein by reference.

Description of the reference numerals

11 … preheat stage; 13 … forming station; 15 … cooling stage; 17. 17a … glass plate; 17a …;23 … lower die (1 st forming die); 25. 25A … upper die (2 nd forming die); 27 … chamber; an upper heater (heating section for temperature increase) 35 …; a 36 … lamp heater; 41 … heat diffusion plate; 43 … lower heater (heating section for temperature rise); 51. 53, 55 … heat insulation frame; 63A, 63B … mold conveying parts; 65 … heat diffusion plate; 67 … upper heater (cooling heater); 73 … heat diffusion plate; a lower heater (cooling heater) of 75 …;81 … heat diffusion plate; 83 … upper heater (heat retaining heating section); 91 … heat diffusion plate; 93 … lower heater (heat retention heating section); 100 … forming apparatus; 111 … forming face; 113 …;113a … inclined plane; 115 … suction orifices; 121 … glass center; 121a …;123 … glass peripheral portion; 125 … gas jet holes; 131 … lower die (1 st forming die); 135 … upper die (2 nd forming die); 141 …, no. 1 forming wire (forming wire); 143 …, 2 nd forming line (forming line).

Claims

1. A glass sheet forming apparatus for heating a glass sheet to form the glass sheet into a desired shape,

the disclosed device is provided with:

at least one 2 nd molding die clamped to the 1 st molding die;

at least one molding stand, wherein the 2 nd molding die is disposed opposite to the 1 st molding die, and the heated glass sheet is molded between the 1 st molding die and the 2 nd molding die;

at least one cooling station for slowly cooling the formed glass sheet; and

the 2 nd molding die and the 1 st molding die of the molding table are in contact with the glass sheet only at the glass outer peripheral portion, and there is no molding die in contact with the glass central portion on the 2 nd molding die side.

2. A glass sheet forming apparatus according to claim 1,

and a suction hole for vacuum forming opened to the forming surface of the 1 st forming mold.

3. A glass sheet forming apparatus according to claim 1 or 2,

the 2 nd forming die comprises: an annular protrusion portion protruding toward the first molding die 1; and a gas ejection hole disposed inside the annular projection, for ejecting gas for pressure forming.

4. A glass sheet forming apparatus according to claim 1 or 2,

the 1 st molding die is disposed below the 2 nd molding die in the vertical direction.

5. A glass sheet forming apparatus according to claim 1 or 2,

the disclosed device is provided with:

6. A glass sheet forming apparatus according to claim 5,

at least one of the heating unit for temperature increase, the heating unit for heat retention, and the heating unit for temperature decrease uses a plurality of lamp heaters for radiation heating as a heat source.

7. A glass sheet forming apparatus according to claim 5,

at least one of the heating unit for temperature increase, the heating unit for heat retention, and the heating unit for temperature decrease uses a plurality of stage heaters for contact heating as a heat source.

8. A glass sheet forming apparatus according to claim 7,

at least one of the heat-retaining heating unit and the temperature-lowering heating unit is provided with a heat diffusion plate between the stage heater and the 1 st molding die.

9. A glass sheet forming apparatus according to claim 5,

in the cooling stage, the cooling heating section is disposed at a position not in direct contact with the 1 st molding die.

10. A glass sheet forming apparatus according to claim 1 or 2,

at least one of the preheating stage, the forming stage, and the cooling stage is provided with a heat insulating frame body that surrounds the outer periphery of each stage and covers a side of the glass sheet supported by the 1 st forming die arranged in the stage.

11. A glass sheet forming apparatus according to claim 10,

the heat insulating frame is disposed in all of the preheating stage, the forming stage, and the cooling stage, and includes a chamber having an internal space for accommodating the preheating stage, the forming stage, and the cooling stage.

12. An apparatus for forming glass sheets as in claim 11,

the inner space of the chamber is filled with an inert gas.

13. A glass sheet forming apparatus according to claim 1 or 2,

the 1 st forming die and the 2 nd forming die are made of carbon.

14. A glass sheet forming apparatus according to claim 1 or 2,

the plurality of preheating stages are arranged along the conveying direction of the 1 st molding die, and the heating temperature of the preheating stages is set to be higher in stages along the conveying direction.

15. A glass sheet forming apparatus according to claim 1 or 2,

the plurality of cooling stages are arranged along the conveying direction of the 1 st molding die, and the heating temperature of the cooling stages is set to be gradually lower along the conveying direction.

16. A glass sheet forming apparatus according to claim 1 or 2,

a plurality of the 1 st forming dies are arranged along the preheating stage, the forming stage, and the cooling stage,

the mold transfer unit simultaneously transfers the plurality of the 1 st molding molds into or out of each of the preheating stage, the molding stage, and the cooling stage.

17. An apparatus for forming glass sheets as in claim 16,

the mode of conveying the 1 st forming die of the die conveying section is a walking beam mode.

18. An apparatus for forming glass sheets as in claim 16,

a plurality of forming lines including the preheating stage, the forming stage, and the cooling stage,

19. An apparatus for forming glass sheets as in claim 18,

the temperature of the 1 st molding die at the time of transferring the glass sheet over the 1 st molding die in the loading section and the unloading section is 300 ℃ or higher.