JP2007269500A - Method and apparatus for forming glass - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for continuously forming glass having uniform heat history while continuously allowing molten glass to flow down into a forming mold; and an apparatus used therefor. <P>SOLUTION: In the method for continuously forming glass by pouring molten glass into one end part of a forming mold 20 having a predetermined product width while allowing the molten glass to continuously flow down and by drawing the glass out of the other end, at least a part of the glass in the glass drawing direction is formed while being subjected to heat exchange. The heat exchange is performed in a portion at least except the near end portion of a bottom plate part 21 of the forming mold 20, thus cooling the glass base. The forming mold 20 of the glass forming apparatus 1 has the bottom plate 21, and a heat exchange unit 24 is arranged in at least a part of the glass drawing direction of the bottom plate 21. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method and an apparatus for molding glass in which internal history, phase separation, and the like with uniform thermal history remain, while molten glass is continuously flowed into a molding mold.

  Usually, to form molten glass continuously in the form of a plate or rod, the molten glass is flowed between the forming rolls and the forming glass is sent out at the same speed as the peripheral speed (double roll method) or a previously prepared forming mold There is a method of drawing molten glass in accordance with the casting speed of cast glass.

As a method for pouring molten glass into a fixed mold and casting it, and extracting the molded glass from the end of the mold, the method described in Patent Document 1 or Patent Document 2 is known. In the method described in Patent Document 1, the molten glass is guided to the vicinity of the molding mold with a pipe, and the molten glass is poured into one end of the molding mold with the distance between the molten glass outlet and the casting surface as close as possible. The molding mold is formed by continuously drawing out glass while being fixed. The mold is temperature controlled in consideration of fusion with the glass, stretch of the formed glass skin, cracking due to cooling, etc. This temperature control is a unilateral cooling operation that cools the entire mold. Done in Further, the method described in Patent Document 2 is the method described in Patent Document 1, wherein a weir is provided at the back portion of the outflow pipe in the molding mold, and glass is continuously formed by applying high-frequency vibration to the weir. To do.
Japanese Patent Publication No. 45-19987 JP-A-50-51516

  However, in these molding techniques, the molten glass is poured into a molding mold through an outflow pipe, and is spread left and right so as to have a predetermined product width, and a glass plate is continuously molded. The region directly below the molten glass flowing down the bottom plate receives heat from the continuously flowing molten glass and becomes the highest temperature in the molding mold, and the temperature decreases as it reaches both sides in the width direction. A temperature gradient (hereinafter referred to as a temperature gradient) is generated from the central region toward both sides. For this reason, the glass is easily fused to the molding mold in the central region where the temperature is high. Further, since the glass plate is cooled and molded in a state having a temperature gradient in the width direction, the thermal history is not uniform, and internal distortion, phase separation, and the like are caused.

  In addition, since the upper surface of the glass is exposed to the outside air, the temperature decreases more quickly than the lower surface of the glass, so that the thermal history is not uniform in the thickness direction as well as the width direction, and internal strain, phase separation, etc. Will occur. This phase separation causes devitrification and the like, which is inconvenient for subsequent heat treatment. Here, the glass bottom means a glass surface in contact with the bottom plate portion and / or the back plate portion of the molding mold.

  Accordingly, this phase separation causes devitrification and the like, which is inconvenient for the subsequent heat treatment and the like, and when crystallized glass is produced, it is inconvenient for the subsequent heat treatment and the like. For example, when this molded glass is used as a base glass and a crystallization process is performed by heat treatment, phase separation occurs, so that uniform crystals cannot be precipitated in the glass phase, and the resulting crystallized glass is obtained. Since the physical properties such as the coefficient of thermal expansion, strength, and surface roughness (Ra) after polishing are not stable, it is inconvenient as a base glass for glass used by heat treatment. Moreover, since internal distortion has occurred, it is easily damaged when heat treatment is performed.

  Furthermore, on the upper surface side, as in the case of the glass bottom surface and / or the back plate side, the central region in the width direction always receives heat from the continuously flowing molten glass, and both side regions are allowed to cool. As a result of this, the temperature drop is rapid, so that a large temperature gradient is generated in the central region and both side regions in the width direction, the heat history is uneven on the upper surface side, and the surface property is also deteriorated. It was.

  Therefore, in a method for forming glass while continuously flowing molten glass into a forming mold, a heat forming history is made uniform, thereby reducing internal distortion and the like, and a glass forming method that does not cause phase separation is required. It has been.

  The present invention has been made in view of such a problem, and the thermal history is made uniform while flowing molten glass continuously into a molding mold, thereby causing less internal distortion and the like, and phase separation also occurs. It is an object of the present invention to provide a method and an apparatus for continuously forming glass without a glass.

  In the method of continuously forming glass by continuously pouring molten glass into one end of a molding mold and drawing glass from the other end while continuously flowing down molten glass, at least one of the glass drawing directions of the glass is performed. Heat exchanging the part, preferably by exchanging heat at least except for the vicinity of the bottom plate part and / or the end part of the back plate part of the molding mold where the molten glass has flowed down, and the central area of the glass in contact with the molding mold The temperature difference between the two side regions and the temperature difference between the glass bottom surface and the top surface were reduced, and it was found that glass having a uniform thermal history could be formed, and the present invention was completed. More specifically, the present invention provides the following.

  (1) In the method of continuously forming glass by pouring into one end of a molding mold having a predetermined product width while continuously flowing molten glass, and drawing the glass from the other end, the glass drawing of the glass A glass forming method in which the forming is performed while heat-exchanging at least a part of directions.

  According to this aspect, in the method of continuously forming glass by pouring into one end of a molding mold having a predetermined product width while continuously flowing molten glass, and drawing the glass from the other end, By cooling or heating at least a part of the glass to exchange heat, the temperature gradient of the glass is reduced, and the temperature difference between the width direction of the glass and the upper and lower methods is reduced. Makes the thermal history uniform. In other words, the region immediately below where the molten glass flows down is the highest temperature by constantly receiving heat from the continuously flowing molten glass. In addition, since the temperature tends to decrease in both side regions of the glass, the temperature difference from the central region that becomes high temperature is further increased and the temperature gradient is increased, so that the molded glass has a non-uniform thermal history, internal strain and For example, by cooling (heat exchanging) the central region where the temperature is high and lowering the temperature to reduce the temperature gradient between the two side regions, The above-mentioned inconvenience can be solved by increasing the temperature of both side regions by heating (heating exchange) the side portions and reducing the temperature gradient with the central region. In addition, the temperature gradient as used in the field of this invention is the inclination of the temperature from a center area to a side part, or the inclination of the temperature of a glass bottom face side and an upper surface side.

  For this heat exchange, for example, a heat exchange unit is provided on the bottom plate portion and back plate portion of the molding mold, and a part of the glass bottom surface is cooled by a heat exchange fluid such as air, water, oil, or a gas burner or the like. This is performed by heating both side portions of the glass using a heating means, or by cooling a part of the upper surface of the glass with a metal plate or the like.

  (2) The glass forming method according to (1), wherein the heat exchange is performed at least in a bottom plate portion and / or a back plate portion of the forming mold.

  The bottom plate part and / or the back plate part of the mold are in direct contact with the glass. For this reason, according to this aspect, heat can be efficiently exchanged.

  (3) The said heat exchange is a glass shaping | molding method as described in (1) or (2) performed in the part except at least the edge part vicinity of the product width direction of the said glass.

  According to this aspect, heat exchange is not performed in the vicinity of both side portions in the product width direction in which the temperature is likely to decrease, so that there is no rapid temperature decrease in the vicinity of the end portion, and the high-temperature central area is heat exchanged. As a result, the temperature difference between the central region and both side regions is reduced. Therefore, the temperature gradient from the central region to both side portions is reduced, and the thermal history of the glass is made uniform.

  (4) The glass forming method according to any one of (1) to (3), wherein a ratio of a width for performing the heat exchange is a ratio of 10 to 80% with respect to the product width.

  (5) The glass molding method according to any one of (1) to (4), wherein a heat exchange unit is provided on a bottom plate portion and / or a back plate portion of the molding mold, and heat exchange is performed by the heat exchange unit.

  (6) The glass forming method according to any one of (1) to (5), wherein cooling is performed by the heat exchange.

  According to this aspect, since the central region where the temperature on the glass bottom surface side and / or the back surface side is high is rapidly cooled, the temperature is efficiently reduced. For this reason, the temperature gradient on the glass bottom and / or back side is flattened.

  (7) The glass molding method according to any one of (1) to (6), in which the molten glass that has flowed down to the molding mold is expanded and restricted to a predetermined glass molding thickness.

  According to this aspect, the molten glass that has flowed down to the molding mold is spread and restricted to a predetermined glass molding thickness, so that a glass having a predetermined thickness can be efficiently molded.

  (8) The glass molding method according to any one of (1) to (7), wherein the upper region of the molding mold is kept warm.

  According to this aspect, since the upper region of the molding mold is kept warm, the temperature gradient on the upper surface of the glass is reduced. That is, by keeping the upper area of the molding mold warm with a heat retaining member or the like, heat dissipation from the upper surface of the glass is suppressed, temperature decrease in both side areas is suppressed, and the temperature difference from the temperature in the central area is more Get smaller.

  (9) Glass molded by the glass molding method according to any one of (1) to (8).

  According to the glass forming method described in any one of (1) to (8) above, as described above, a glass having a uniform thermal history and less internal strain can be obtained. For this reason, it is preferred as a base glass for crystallized glass, especially for applications requiring a heat treatment step.

  (10) Crystallized glass glass formed by the glass forming method according to any one of (1) to (8).

  (11) In a continuous glass forming apparatus having a forming mold and an outflow device, the forming mold has a bottom plate portion and / or a back plate portion, and the bottom plate portion and / or the back plate portion has a glass drawing direction. A glass continuous forming apparatus in which a heat exchange unit is disposed at least in part.

  (12) The glass continuous forming apparatus according to (11), wherein the heat exchange unit is disposed in a portion excluding at least the vicinity of an end portion in the product width direction of the bottom plate portion and / or the back plate portion.

  (13) The glass continuous forming apparatus according to (11) or (12), wherein the heat exchange unit has a width dimension in a range of 10 to 80% with respect to a glass forming width.

  (14) The continuous molding apparatus for glass according to any one of (11) to (13), wherein the molding mold includes the bottom plate portion, the back plate portion, and a guide portion.

  (15) The heat exchange unit includes a first heat exchange unit located below the back plate portion, a second heat exchange unit located below the outflow pipe, and a glass drawing direction side of the second heat exchange unit. The glass continuous forming apparatus according to (14), comprising: a third heat exchange unit located in

  (16) The roller according to any one of (11) to (15), wherein the roller is positioned above the bottom plate portion of the molding mold on the glass drawing direction side of the outflow device and disposed in the glass molding width direction. Glass continuous forming equipment.

  (17) In any one of (11) to (16), a heat insulating plate is disposed above the molding mold so as to cover the molten glass flowing down from the outflow device onto the molding mold. Glass continuous forming equipment.

  (18) The glass continuous forming apparatus according to any one of (14) to (17), wherein the back plate portion is formed with a heat exchange chamber.

  (11)-(18) The glass continuous shaping | molding apparatus expand | deploys the glass shaping | molding method of (1)-(8) mentioned above as a glass continuous shaping | molding apparatus. According to the glass continuous forming apparatus, the same effects as those described in the glass forming method described above can be obtained. According to the continuous glass molding apparatus of (15), since the glass bottom surface can be individually cooled, it is possible to set optimum cooling conditions in each part and efficiently cool the glass bottom surface. it can. Further, according to the glass continuous molding apparatus of (18), the back plate portion in contact with the molten glass can be cooled by a cooling fluid such as water, so that the temperature on the glass bottom surface and / or the back surface side is rapidly reduced. Can be made. In addition, when there are a plurality of heat exchange chambers formed in the back plate portion, for example, since the ratio of both sides of the back plate portion contacting the molten glass is small, the cooling condition is relaxed, etc. It is preferable because optimum cooling conditions can be set at each part of the part and the glass bottom can be efficiently cooled.

  (19) Glass molded by the continuous glass molding apparatus according to any one of (11) to (18).

  (20) A glass for crystallized glass formed by the continuous glass forming apparatus according to any one of (11) to (18).

  (21) In the method for continuously molding glass by continuously pouring molten glass into one end of a molding mold having a predetermined product width and drawing glass from the other end, in the molding mold, A method of adjusting the cooling in the product width direction of the bottom plate portion and / or the back plate portion so that the temperature gradient in the product width direction of the glass approaches flat.

  According to this aspect, since the temperature gradient in the product width direction of the glass is reduced, the glass has a small temperature difference between the central region and both side regions, and the central region and both side regions of the glass are under the same conditions. Since it is cooled and solidified, the thermal history of the glass is made uniform.

  As a method for such adjustment, the temperature in the width direction is measured in advance experimentally by measuring the temperature at several points in the width direction near the contact surface with the glass of the bottom plate portion and / or the back plate portion of the mold. Change the degree of cooling to find a cooling condition that brings the temperature gradient of the glass closer to flatness, and adjust it to meet that cooling condition in actual manufacturing, or in the actual manufacturing, several points in the width direction For example, there is a method of adjusting the cooling by changing the degree of cooling in the width direction so that the temperature gradient of the glass approaches flat while measuring the temperature.

  According to the glass forming method and the glass forming apparatus of the present invention, the temperature gradient in the glass width direction is reduced. For this reason, the glass is similarly cooled and solidified, and the thermal history is made uniform.

  In addition, since the glass top surface is exposed to the outside air, the temperature is likely to be lower than the glass bottom surface, and the temperature difference between the glass bottom surface and the glass bottom surface is large, but the heat difference reduces the temperature difference between the glass bottom surface and the glass top surface. For this reason, since the glass bottom surface and the top surface are similarly cooled and solidification proceeds, there is little deviation between the bottom surface and the top surface when the glass is pulled out, and phase separation is unlikely to occur. Therefore, it is possible to form a glass having a uniform heat history without devitrification.

  In addition, by covering the upper area of the upper surface of the molten glass with a heat insulating member and maintaining the temperature, the temperature decrease in both side areas of the upper surface of the glass is suppressed, and the temperature gradient is reduced on the upper surface side of the glass, so the thermal history is even more uniform. It becomes.

  Thus, since the glass of the present invention has a uniform thermal history and no phase separation, it is a homogeneous glass and is used as a base glass for crystallized glass, especially for applications requiring a heat treatment step. As preferred.

  Hereinafter, the present invention will be specifically described.

  The glass molding method of the present invention, when molten glass is continuously flowed down, poured into one end of a molding mold having a predetermined product width, and glass is drawn out from the other end to continuously mold the glass. The glass is molded while exchanging at least a part of the glass drawing direction.

  This heat exchange is preferably performed at the bottom plate portion and / or the back plate portion of the mold. This is because the bottom plate portion and / or the back plate portion are in direct contact with the glass, so that heat exchange can be efficiently performed. In addition, this heat exchange is performed by bringing the heat exchange fluid into direct contact with the bottom plate portion and / or the back plate portion, providing a heat exchange unit, attaching a cooling fin to the back surface of the bottom plate portion and / or the back plate portion, etc. Good.

  The heat exchange is preferably performed at least at a portion excluding the end in the width direction. Accordingly, heat is not exchanged at the end portion where the temperature is easy to cool, but heat exchange is performed for the other end portions, so that the temperature can be made close to the temperature at the end portion that is easy to cool and the thermal gradient of the glass can be made uniform. The ratio of the width for performing this heat exchange is 80% at the upper limit, preferably 65%, more preferably 55% with respect to the glass product width, and 10%, preferably 15%, more preferably 20% at the lower limit. % Width dimension is preferable. By exchanging heat in this range, both side regions where the temperature is lowered are not cooled because heat exchange is not performed. For this reason, the difference with the temperature of the central region of the glass cooled by heat exchange decreases, and the temperature gradient decreases.

  As described above, the heat exchange may be a method in which the heat exchange fluid is brought into direct contact, but a heat exchange unit is preferable because it can be performed more efficiently and the heat exchange site can be easily specified. As a structure of the heat exchange unit, for example, a heat exchange chamber in which a heat exchange fluid circulates is provided in the bottom plate portion and / or the back plate portion. The heat exchange fluid is not particularly limited as long as it can cool or heat the bottom plate portion and / or the back plate portion, and may be liquid or gas, but is preferably liquid from the viewpoint of thermal conductivity. . Further, one or more heat exchange units may be used. Note that this heat exchange is preferable because it is more efficient and less costly to cool the region where the temperature is higher than the surroundings, rather than heating the region where the temperature is lowered.

  Next, an embodiment of the present invention will be described with reference to the drawings. In the following description of the embodiments, the same constituent elements are denoted by the same reference numerals, and the description thereof is omitted or simplified.

<Configuration of glass forming apparatus>
FIG. 1 is a schematic cross-sectional view of a glass forming apparatus 1 according to an embodiment of the present invention, and FIG. 2 is a plan view of the glass forming apparatus 1 shown in FIG. The glass forming apparatus 1 includes an outflow device 10 for flowing the molten glass downward, a forming mold 20 provided below the outflow device 10, a heat retaining member 30 covering an upper area of the forming mold 20, and a downflow And a roller 40 that regulates the thickness while spreading the molten glass A in the width direction. Further, an air blower 50 for cooling the glass is provided near the front (glass flow direction) end portion of the molding mold 20 at the upper part of the glass surface. Although not shown, a conveyor and a slow cooling furnace are provided in front of the molding mold 20 (in the glass flow direction) for transporting and cooling the molded glass.

(Spill device)
The outflow device 10 includes a glass melting tank (not shown) in which molten glass is accommodated, and an outflow pipe 11 that extends downward from the glass melting tank and flows out the molten glass. Although the shape of the outflow pipe 11 is not particularly limited, the flow of the molten glass is made smooth, the glass does not stagnate at the tip, and devitrification hardly occurs, and the glass is uniform in the width direction. It is preferable that the distal end of the distal end widens in the width direction so that the central portion of the distal end opening portion is narrower than both end portions. Moreover, depending on the case, you may provide the heating apparatus heated so that the temperature of the molten glass which flows down from the outflow pipe | tube 11 may become a softening point or more.

(Molding mold)
The molding mold 20 is provided below the outflow pipe 11 and includes a bottom plate portion 21 that receives the molten glass A that has flowed down from the outflow device 10. Glass is formed by the bottom plate portion 21, and further, a back plate portion 22 that prevents the molten glass A from flowing backward (in the counter-flow direction of the glass), and a pair of guide portions 23 that form the glass side surfaces, 23 '. In addition, the heat exchange unit 24 may be provided in the central region in the product width direction of the bottom plate portion 21 in order to exchange heat such as cooling at least part of the glass. The heat exchange unit 24 is located below the back plate portion 22, and is located below the first heat exchange unit 24 </ b> A for cooling the center region in the product width direction of the bottom surface of the back plate portion 22 and the outflow pipe 11. The second heat exchange unit 24B that cools the central region in the product width direction of the glass bottom immediately below the molten glass A that has flowed down is positioned in front of the second heat exchange unit 24B, and the molten glass A is pushed by the roller 40. It is formed from a third heat exchange unit 24C that cools the central region of the bottom surface of the glass that has been spread and formed.

  Each of the heat exchange units 24A, 24B, and 24C is formed in a cavity having a surface that abuts the glass bottom surface as a part of the outer wall, and feeds a cooling fluid such as water or air from one inlet 24a. The cooling fluid is not shown in the figure, but is sent to the cooler through the pipe and cooled to a predetermined temperature, and the flow rate is adjusted by a flow controller. The heat exchange units 24A, 24B, and 24C can be cooled under predetermined cooling conditions. Further, the leading end portion of the inlet port 24a is located on the lower side in the internal cavity in each of the heat exchange units 24A, 24B, and 24C, and the leading end portion of the outlet port 24b is located on the upper ceiling surface in the cavity. The cooled cooling fluid is introduced from below in the cavity, stays in the cavity and is discharged from above, and the cooling fluid cooled in the cavity fills the ceiling in the cavity. At this time, the cooling fluid moves upward from below in the cavity, and the cooling fluid that has moved upward absorbs the heat conducted from the bottom surface of the glass and is discharged outside. It is circulated without mixing with the cooling fluid that does not absorb the heat. The cooling mechanism using the cooling fluid is an example, and is not limited to this. Except for the vicinity of the end portion of the bottom plate portion 21 and / or the back plate portion 22 of the molding mold 20 in the product width direction. Any mechanism may be used as long as it can efficiently cool the site, preferably the vicinity of the central region. The cooling fluid is not particularly limited as long as it can cool the bottom plate portion 21 and / or the back plate portion 22 and may be liquid or gas, but is preferably liquid from the viewpoint of thermal conductivity. In particular, water is preferable because it can be handled safely, simply and easily, and the cost is low.

  The heat exchange units 24A, 24B, and 24C have an upper limit of 80%, preferably 65%, more preferably 55%, and a lower limit of 10%, preferably 15%. Preferably, it is formed in a range of a width dimension of 20%. When it is narrower than 10% of the product width, the bottom surface of the molten glass A that has flowed down cannot be sufficiently cooled and cannot be lowered to a predetermined temperature. On the other hand, if it is wider than 80%, both side regions are also cooled, and the temperature difference from the central region cannot be reduced.

  The back plate portion 22 has an inclined surface that descends toward the glass drawing direction, and has a prismatic shape with a substantially triangular cross section. Inside, one or a plurality of heat exchange chambers 22A are formed. (In this embodiment, it is divided into a central area and both side areas and is formed into three chambers). The cross-sectional shape of the back plate portion 22 is not limited to this, and may be, for example, a substantially trapezoidal shape.

  Moreover, the surface which contacts the molten glass A of the backplate part 22 smoothes the flow of the molten glass A, prevents the glass from stagnating at a specific location, and prevents the occurrence of folding and devitrification. However, the present invention is not limited to this, and may have no inclined surface. In the case of the inclined surface, the angle can be appropriately selected within the range of 5 ° to 85 °, preferably 10 ° to 70 °, but the range of 15 ° to 60 ° is particularly preferable. In addition, as shown in FIG. 2, the molten glass A that has flowed down into the shape of an inclined surface has an arch shape in plan view, so that the shape of the plan view is arched in accordance with the expanded shape. You may form in. In this case, the back plate portion 22 and the guide portions 23 and 23 'may be integrated.

  The heat exchange chamber 22A is formed in a cavity having a surface abutting the bottom surface of the molten glass A as a part of the inner wall, and a cooling fluid such as water or air is fed from one inlet 22a to the other. The cooling fluid is circulated by being taken out from the discharge port 22b. Although not shown, this cooling fluid is sent to a cooler through piping and cooled to a predetermined temperature, and the flow rate is adjusted by a flow rate controller. Each heat exchange chamber can be cooled under a predetermined cooling condition. The introduction port 22a is located below the discharge port 22b, and the cooled cooling fluid is introduced from the introduction port 22a into the lower part of the cavity of the heat exchange chamber 22A, stays in the cavity, and is discharged from the upper discharge port 22b. The cooling fluid that has been discharged and cooled in the cavity circulates. At this time, the cooling fluid is circulated without being mixed with the cooling fluid that does not absorb the heat of the glass bottom surface. The structure of the heat exchange chamber 22A and the cooling mechanism using the cooling fluid are merely examples, and the present invention is not limited to this. The molten glass A that flows in contact with the inclined surface of the back plate 22 is formed by the back plate. Any structure that can cool the bottom surface of the glass to such an extent that it does not fuse to the surface of the portion 22 may be used. Further, the cooling fluid is not particularly limited as long as it can cool the back plate portion 22, but as described above, water is most preferable.

  The guide portions 23 and 23 'are for preventing the molten glass A that has flowed down from flowing out in the width direction, and for forming the side surface of the glass, or for regulating the thickness of the glass together with the roller. 21 may be separate from or integrated with 21. Further, although not shown in the drawing, it is preferable that the guide portions 23 and 23 'can be heated by a heater or the like so that the molten glass A that has flowed down does not rapidly cool by touching the guide portions 23 and 23. The guide portions 23 and 23 'and the back plate portion 22 may be unnecessary by adjusting the outflow amount and the drawing speed of the glass.

  As a material constituting the molding mold 20, a material used for normal glass molding, for example, a ductile is sufficient, and is not particularly limited. However, from the viewpoint of temperature controllability, glass fusing property, and the like. Carbon material, SiC, or a composite material of SiC and carbon may be used.

(Insulation material)
The heat retaining member 30 is for retaining the upper region of the molten glass A that has flowed down to the molding mold 20, and is disposed so as to cover the molten glass A while being held by a holding material 31 such as an iron plate. ing. Thereby, since the cooling of the molten glass A in both side regions is suppressed, the temperature gradient on the upper surface of the molten glass A is reduced, the temperature difference between the central region and both side regions is reduced, and it is uniformly cooled and solidified. As a result, the thermal history of the glass is made uniform. In addition, as a material of the heat retaining member 30, a heat insulating mat made of fireproof fiber or the like can be used.

<Glass molding method>
Next, a glass forming method using the glass forming apparatus 1 will be described with reference to FIGS. 1 and 2.

  A cooling fluid such as water or air is introduced into each of the heat exchange units 24A, 24B, and 24C from the introduction port 24a at a predetermined temperature and flow rate via a cooler and a flow rate controller (not shown). After the inside has been retained, it is circulated by taking it out from the discharge port 24b, and the central region in the product width direction of the bottom plate portion 21 is cooled. In addition, each back plate portion 22 also introduces water or air cooling fluid from the introduction port 22a at a predetermined temperature and flow rate via a cooler and a flow rate controller (not shown) to stay in the cavity. After that, it is circulated by taking it out from the discharge port 22b, and the back plate part 22 is cooled.

  In this state, the molten glass is caused to flow down from the outflow pipe 11 of the outflow device 10 and is poured onto the bottom plate portion 21 of the molding mold 20. The molten glass A that has been poured produces a constant surface flow on the pouring surface, that is, a surface receding flow opposite to the pulling direction, in addition to the surface flow in the pulling direction and the width direction. This backward flow is cooled in contact with the inclined surface of the back plate portion 22 of the molding mold 20, and gradually descends as a high-viscosity backward flow, and further flows to the bottom plate portion 21 to form the bottom surface of the molded glass. Further, the surface flow in the pulling direction is expanded in the width direction by the roller 40 so that the thickness of the formed glass is regulated to be a constant thickness and drawn forward, and then cast glass B is blown by air from the blower 50. After the upper surface is sufficiently cooled and solidified, the cast glass B is placed on a conveyor (not shown) and sent to a cooling furnace.

  In the molding of the glass of the present invention, the region immediately below where the molten glass flows down of the bottom plate portion 21 and / or the back plate portion 22 receives heat from the continuously flowing molten glass, so the temperature becomes the highest. Like the temperature gradient curve indicated by the broken line, the glass bottom surface has a large temperature gradient from the central region to both side regions, but the second heat exchange unit 24B, further the first heat exchange unit 24A, and the third heat When the central area of the glass bottom surface is cooled by the replacement unit 24C, the central area of the glass bottom surface is cooled and the temperature is lowered, and as shown by the solid line in FIG. A temperature gradient curve with a reduced temperature gradient is reduced, and the thermal history of the glass is made uniform. Further, the cooling of the bottom plate portion 21 has an effect of lowering the temperature of the central region of the upper surface of the molten glass A in addition to the effect of lowering the temperature of the central region of the glass bottom surface. FIG. 3 is a schematic diagram for explaining the temperature gradient curve in the product width direction on the glass bottom surface. The solid curve is a temperature gradient curve when the central region of the glass bottom surface is cooled, and the dashed curve is It is a temperature gradient curve when not cooling the center area | region of the glass bottom face.

  Further, as shown in FIG. 2, the backward flow of the molten glass A spreads on both sides while contacting the central area of the inclined surface of the back plate portion 22. Therefore, it is preferable that the back plate portion 22 has a cooling temperature of the heat exchange chamber 22A at the center portion lower than the cooling temperature of the heat exchange chamber 22A at both side portions.

  Moreover, since the heat retaining member 30 is disposed above the molding mold 20 so as to cover the molten glass A that has been poured in, heat dissipation from the upper surface of the glass is suppressed. For this reason, the temperature decrease due to heat dissipation is suppressed in both side regions on the upper surface of the glass, and the temperature is higher than that without the heat retaining member 30, and the temperature gradient on the upper surface of the glass is reduced. That is, the temperature gradient curve shown by the one-dot chain line in FIG. 4 in which the temperature in both side regions is increased becomes the temperature gradient curve in the case where there is no heat retaining member shown by the broken line in FIG. 4, and the temperature gradient is reduced. Furthermore, although the center area in the product width direction of the glass bottom surface is cooled by the heat exchange unit 24 as described above, the temperature decreases, and accordingly, the temperature of the center area of the upper surface also decreases. The temperature gradient curve is a further decrease in the temperature in the central region. That is, in the temperature gradient curve indicated by the one-dot chain line, the temperature gradient curve indicated by the solid line in FIG. 4 in which both sides have substantially the same temperature and the temperature in the central region has been lowered becomes further flattened. The thermal history of the glass becomes uniform. FIG. 4 is a schematic diagram for explaining a temperature gradient curve in the product width direction on the glass upper surface, where the solid curve cools the central region in the product width direction on the glass bottom surface, and further, a heat retaining member Is a temperature gradient curve when the upper part of the glass is covered, and the broken curve is a temperature gradient curve when neither cooling of the central area of the glass bottom surface nor covering of the upper surface of the glass by the heat retaining member is performed. The curve of the alternate long and short dash line is a temperature gradient curve when the upper surface of the glass is covered with a heat insulating member without cooling the central region of the glass bottom.

  In general, to reduce the temperature on both sides, it is common practice to raise the temperature in the side area by heating the sides with a heating means such as a gas burner. Then, although the variation in heating is likely to occur depending on the gas supply amount, pressure, etc., in the method in which the heat retaining member 30 is provided, the upper surface of the molten glass A is generally kept warm, so the temperature drop in both side regions Is suppressed.

  Examples relating to the glass molding method of the present invention will be described below. As the glass forming apparatus, basically the same apparatus as described in the embodiment of the present invention was used. This is merely an example, and the technical scope of the present invention is not limited to this.

  The type of glass used is crystallized glass (WMS-15, manufactured by OHARA INC.), And the mold 20 has a bottom plate portion 21 of 25 mm × 500 mm × 500 mm, and a triangular pyramid-shaped back plate portion 22. The bottom surface is 160 mm × 330 mm, the height is 50 mm (the angle of the inclined surface is about 17.5 °), the height of the guide portions 23 and 23 ′ is 19 mm, and each material is stainless steel.

  Three heat exchange units 24A, 24B, and 24C having an internal volume of 15 mm × 40 mm × 100 mm are provided in the center region in the glass product width direction of the bottom plate portion 21 (the width of the heat exchange units 24A, 24B, and 24C). Is equivalent to about 30% of the product width). Further, the back plate part 22 was divided into 100 mm width dimensions to form three heat exchange chambers 22A. And it has arrange | positioned so that the lower front-end | tip part of the inclined surface may become a distance of 200 mm from the glass drawer direction side edge part of the baseplate part 21. FIG. In addition, the pair of guide portions 23 and 23 are arranged at positions where the distance from the central axis in the glass drawing direction is 165 mm so that glass having a width of 330 mm can be formed.

  The heat retaining member 30 is a “fiber monoflux” manufactured by Toshiba Monoflux Co., Ltd. having dimensions of 400 mm (h) × 150 mm (w) × 25 mm (t). The heat retaining member 30 is held by a holding material 31 and is a molding mold. It was arranged at a position of about 50 mm above the 20 bottom plate portions 21. The roller 40 has a diameter of 20 mm, a material of iron, and a cast glass B having a thickness of 19 mm.

  A quartz crucible having an internal volume of 200 liters was used for melting the glass. After the glass raw material was melted, the defoamed and homogenized molten glass was lowered to a temperature of 1290 ° C. and was discharged from the platinum outflow pipe 11 having an inner diameter of 25 mm. In addition, the front-end | tip opening part of the outflow tube 11 was made into the rectangular shape of 8 mm x 80 mm.

  The molten glass A that has flowed out of the outflow pipe 11 is water having a temperature of 30 ° C. that circulates in the heat exchange units 24A, 24B, and 24C formed in the bottom plate portion 21 of the molding mold 20 in the center region in the product width direction of the bottom surface. The cast glass B is cooled from the end of the molding mold 20 in accordance with the amount of glass that is cooled and is spread to a predetermined glass thickness by the roller 40 and flows out so that the thickness of the cast glass B becomes 19 mm. The glass was continuously drawn and molded while the speed of the conveyor was adjusted while being pulled out and placed on a conveyor moving at a constant speed in the slow cooling furnace.

  In the above glass molding, the temperature of the bottom plate portion 21 of the molding mold 20 was measured at the position indicated by the mark ● in FIG. The temperature was measured by making a hole in the bottom plate portion 21 reaching 2.5 mm below the surface that contacts the glass from the back surface by the above-mentioned ● mark, and inserting the tip of the thermocouple into the hole.

  As a result, the temperature of the part (the front / medium, middle / medium equivalent part in FIG. 5) of the bottom plate portion of the molding mold is significantly lower than the part where the heat exchange unit is not provided. Therefore, in this part, the heat is exchanged and the glass is cooled. For this reason, the center area | region in the product width direction of glass is cooled, and the temperature gradient of the width direction is planarized.

It is a schematic sectional drawing of the glass forming apparatus which concerns on one Embodiment of this invention. It is a top view of the shaping | molding apparatus which concerns on the said embodiment. It is a schematic diagram explaining the temperature gradient curve of the product width direction of a glass bottom face. It is a schematic diagram explaining the temperature gradient curve of the product width direction of glass upper surface. In FIG. 2, it is a figure which shows the temperature measurement position in the baseplate part of a shaping | molding die.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Glass forming apparatus 10 Outflow apparatus 11 Outflow pipe 20 Molding mold 21 Bottom plate part 22 Back plate part 22A Heat exchange chamber 23 Guide part 24 Heat exchange unit 24A 1st heat exchange unit 24B 2nd heat exchange unit 24C 3rd heat exchange unit 30 Thermal insulation member 40 Roller A Molten glass B Cast glass

Claims (21)

In a method of continuously forming glass by pouring into one end of a molding mold having a predetermined product width while continuously flowing down molten glass, and pulling out the glass from the other end,
A glass forming method in which the forming is performed while heat-exchanging at least a part of the glass in the glass drawing direction.   The glass forming method according to claim 1, wherein the heat exchange is performed at least in a bottom plate portion and / or a back plate portion of the forming mold.   3. The glass forming method according to claim 1, wherein the heat exchange is performed in a portion excluding at least an end portion in the product width direction of the glass.   The glass forming method according to any one of claims 1 to 3, wherein a ratio of a width for performing the heat exchange is a ratio of 10 to 80% with respect to the product width.   The glass molding method according to claim 1, wherein a heat exchange unit is provided on a bottom plate portion and / or a back plate portion of the molding mold, and heat exchange is performed by the heat exchange unit.   The glass forming method according to claim 1, wherein cooling is performed by the heat exchange.   The glass molding method according to any one of claims 1 to 6, wherein the molten glass that has flowed down to the molding mold is spread and regulated to a predetermined glass molding thickness.   The glass molding method according to claim 1, wherein an upper region of the molding mold is kept warm.   A glass formed by the glass forming method according to claim 1.   A glass for crystallized glass formed by the glass forming method according to any one of claims 1 to 8. In a continuous glass molding apparatus having a molding mold and an outflow device,
The molding mold has a bottom plate portion and / or a back plate portion,
A glass continuous forming apparatus in which a heat exchange unit is disposed in at least a part of the bottom plate portion and / or the back plate portion in the glass drawing direction.   The said heat exchange unit is a glass continuous shaping | molding apparatus of Claim 11 arrange | positioned in the part except at least the edge part vicinity of the product width direction of the said baseplate part and / or the said backplate part.   The said heat exchange unit is a continuous molding apparatus of the glass of Claim 11 or 12 whose width dimension is the range of 10 to 80% with respect to a glass forming width.   The said shaping | molding mold is a continuous shaping | molding apparatus of the glass in any one of Claim 11 to 13 comprised from the said baseplate part, the said backplate part, and a guide part.   The heat exchange unit is located on a glass drawing direction side of the first heat exchange unit located below the back plate portion, a second heat exchange unit located below the outflow pipe, and the second heat exchange unit. The glass continuous forming apparatus according to claim 14, comprising a third heat exchange unit.   The continuous molding of glass according to any one of claims 11 to 15, wherein a roller is positioned above the bottom plate portion of the molding mold on the glass drawing direction side of the outflow device and is disposed in the glass molding width direction. apparatus.   The glass continuous molding according to any one of claims 11 to 16, wherein a heat insulating plate is disposed above the molding mold so as to cover the molten glass flowing down from the outflow device onto the molding mold. apparatus.   The continuous forming apparatus for glass according to any one of claims 14 to 17, wherein the back plate portion is formed with a heat exchange chamber.   The glass shape | molded by the continuous shaping | molding apparatus of the glass in any one of Claims 11-18.   Glass for crystallized glass formed by the continuous glass forming apparatus according to any one of claims 11 to 18. In a method of continuously forming glass by pouring into one end of a molding mold having a predetermined product width while continuously flowing down molten glass, and pulling out the glass from the other end,
A method of adjusting the cooling in the product width direction of the bottom plate portion so that the temperature gradient in the product width direction of the glass in the molding mold approaches flat.

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