JP5537278B2 - Manufacturing methods for glass plates, press molding materials, optical elements, and thin glass - Google Patents

Description

  The present invention relates to a method for continuously forming a glass plate that requires a high degree of homogeneity such as optical glass from molten glass, a glass material for press molding using the glass plate produced by the method, an optical element, and a thin plate. The present invention relates to a method of manufacturing each glass.

  In the technology of forming glass with a high degree of homogeneity, such as optical glass, and with a high liquidus temperature (easily crystallized) as compared with plate glass for building materials, it has conventionally flowed out of an orifice with a small cross-sectional area. A method for producing a glass plate having a large cross-sectional area by continuously casting the obtained glass into a fixed mold installed horizontally is known.

  Patent Document 1 discloses a glass forming method in which molten glass is continuously discharged from an outflow pipe and poured into a mold to form the glass, and the formed glass is drawn out from a drawer opening provided on the side of the mold. Has been. In Patent Documents 2, 3, and 4, when the glass is formed by continuously flowing out the molten glass from the outflow pipe and pouring it into the mold, the glass is cooled by pressing the cooling plate against the upper surface of the softened glass in the mold. By doing so, it is described that a glass plate having a uniform thickness is obtained. The drawn glass plate is processed into a glass material for press molding an optical element such as a lens after annealing.

  In the column of the prior art of Patent Document 1, “In the molding technique using a fixed weir-groove mold provided directly under the glass outflow pipe, the upper surface of the mold directly under the outflow pipe is always taken from the continuously flowing molten glass. When heated, it becomes the highest temperature in the mold, and it becomes easy to fuse with glass. To prevent this fusion, the upper surface of the mold is controlled to be lower than other parts, and it is balanced. It is necessary to cool the mold with the device indicated as the cooler 3, 3 'and prevent the glass from fusing, as it is described. " Has been made.

Japanese Patent Publication No. 5-31505 JP 2002-265229 A JP 2004-292274 A JP 2009-46360 A

  In the mold described in Patent Document 1, coolers 3 and 3 ′ are arranged at a position directly below the outflow pipe and at a position downstream thereof in a direction orthogonal to the glass drawing direction, and a weir part and a side wall The coolers 1 and 8 are arranged respectively (FIGS. 1 to 2). Further, in the mold shown in FIGS. 5a and 5b, which is a conventional example in Patent Document 1, cooling is performed by disposing the cooler 1 directly below the outflow pipe and the weir part or the bottom part of the weir part. Promoting.

  When molding molten glass with the mold described in Patent Document 1, in order to prevent the glass from fusing to the mold, especially when the glass plate is molded while promoting cooling of the mold by the coolers 3 and 3 ′. When the width of the mold is relatively wide, and as a result, the width of the glass plate to be molded is relatively wide and the thickness of the glass plate to be molded is relatively thin (for example, the width is 100 mm or more and the thickness is 6 to In the range of 30 mm and width / thickness of 3-50, the flow rate of the molten glass flowing out from the orifice is relatively small (for example, 20-140 mL / min), and the thickness becomes uneven due to poor elongation. In some cases, the glass may be bent into the glass, or unevenness called a tree pattern may be unevenly formed on the bottom surface of the glass.

  The portion where the folding occurs is not suitable for a material for an optical element because optical homogeneity is impaired. If the glass material for press molding made from a glass plate is not made using glass of a predetermined amount (constant weight) one by one, the molding accuracy at the time of press molding will decrease. If the thickness and width of the glass plate are constant, the glass plate can be divided into equal intervals in the shape of a bowl to obtain glass pieces of equal weight called cut pieces. Many glass materials can be made. However, if there is a non-uniform tree pattern on the bottom surface of the glass plate, the plate thickness varies, and even if the glass plate is divided at equal intervals, it is not possible to obtain an equal weight cut piece or glass material. Moreover, the same result is obtained even in a glass shape having a non-uniform thickness or warping due to poor elongation. Therefore, the bottom surface of the glass plate must be processed flat. Optical glass uses a large amount of expensive transition metal components such as rare earth components to increase the refractive index and expensive fluoride raw materials for low dispersion, but it is expensive by scraping the glass plate surface extensively. The problem is that glass is not used at all and becomes waste.

  Therefore, the present invention solves the above problems, prevents the glass from fusing to the mold, prevents the occurrence of folding and non-uniform denim, and has a good shape, that is, a high quality with a uniform thickness and low warpage. A method for producing a glass plate that stably forms a simple glass plate, and a method for producing a glass material for press molding, an optical element, and a thin plate glass using the glass plate produced by the above method are provided. The purpose is to do.

  As a result of various studies to solve the above problems, the inventors have a relatively wide mold, a relatively thin glass plate to be formed, and a small flow rate of molten glass flowing out from the orifice. Even when casting the molten glass and forming it into a flat plate shape, when the upper surface of the mold is viewed in plan, the upper surface of the molten glass flows out from the position immediately below the orifice and the position immediately below the orifice in the forming direction. When the area to be cooled is locally cooled and the area is cooled to have substantially the same width toward the downstream, folding into the inside of the glass occurs or the glass bottom is called a tree pattern The present invention has been completed by finding that a glass plate can be formed without causing the problem that unevenness occurs unevenly.

The present invention is as follows.
[1]
It flows out of the orifice into a mold having a pair of opposing side walls that define the width of the glass plate and a bottom portion having a surface (hereinafter referred to as an upper surface) for molding one of the two opposing main surfaces of the glass plate. Molten glass is continuously cast, and the glass cast along the both side walls is continuously formed in one direction (hereinafter referred to as the molding direction) from the upstream side to the downstream side, and a flat glass plate is continuously formed. A method for producing a glass plate, comprising:
Casting of the molten glass and forming into a flat plate shape are substantially the same width extending in the forming direction from the position immediately below the orifice and the position immediately below the orifice when the upper surface is viewed in plan. A method for producing a glass plate, which is carried out while locally cooling a region having a temperature (hereinafter referred to as a cooling promotion region).
[2]
The said flat glass plate is a manufacturing method as described in [1] whose ratio of the width | variety with respect to thickness is the range of 3-50.
[3]
The width of the cooling promotion region is the manufacturing method according to [1] or [2], which is in a range of 5 to 40% of the width of the upper surface.
[Four]
The said cooling acceleration | stimulation area | region is a manufacturing method of the glass plate in any one of [1]-[3] which has a symmetrical shape with respect to the virtual straight line which passes the position right under an orifice and extends toward a forming direction.
[Five]
The cooling promotion region is provided between a position immediately below the orifice and a position where the glass temperature is in the range of the glass transition temperature Tg-100 ° C. to Tg + 100 ° C. in the forming direction [1] to [4]. The manufacturing method of the glass plate in any one of.
[6]
The bottom of the mold has at least two through-holes inside, substantially orthogonal to the side wall and substantially parallel to the top surface,
One of the through holes is disposed at a position immediately below the orifice, and at least one of the remaining holes is disposed at a position downstream of the orifice immediately below,
The through hole has an opening on the side surface of the bottom portion connected to the outer side surface of the side wall,
Each through-hole has at least one discharge port for discharging a cooling medium on a side surface, and the size and / or the cooling medium discharged from the discharge port can flow out of the through-hole from the opening. A cooling medium supply pipe having a shape is disposed such that at least one of the discharge ports is located in the through hole;
The cooling medium supply pipes have the same number and the same shape of discharge ports,
Cooling the area,
Introducing a cooling medium into the cooling medium supply pipe disposed in the through hole, discharging the cooling medium from the discharge port, and cooling the upper surface in the vicinity of the discharge port.
[1] The production method according to any one of [4].
[7]
The number of the said through-holes and the said cooling-medium supply pipe | tube is a manufacturing method as described in [ 6 ] which is the range of 2-10.
[8]
In the manufacturing method of the glass material for press molding for heating, softening and press molding,
A glass plate is produced by the method according to any one of [1] to [7], the glass plate is divided to produce a plurality of glass cut pieces, and the glass piece for press molding that processes the cut pieces Production method.
[9]
In the method of manufacturing an optical element for producing a glass optical element through a process of heating, softening and press molding a glass material,
A method for producing an optical element, comprising producing a glass material for press molding by the method according to [8], heating, softening, and press molding the glass material.
[Ten]
A method for producing a thin glass, comprising producing a glass plate by the method according to any one of [1] to [7], and producing a thin glass from the glass plate through a process including slicing.

  According to the present invention, the width of the mold is relatively wide, and therefore the width of the glass plate to be molded is relatively wide, the thickness of the glass plate to be molded is relatively thin, and the flow rate of the molten glass flowing out from the orifice is small. Even in such a case, the glass plate can be formed without causing problems such as folding into the glass or unevenness called dendrites on the bottom surface of the glass. Furthermore, a method of cutting a glass plate obtained by this method and producing a press molding material, a method of press molding using this press molding material, and a method of producing an optical component such as a lens from the obtained molded product And the manufacturing method of the sheet glass which produces sheet glass through the process including a slice process from the said glass plate can be provided.

It is the schematic which planarly viewed the casting_mold | template 1 which is an example of the casting_mold | template used with the manufacturing method of this invention. The vertical cross section in AA of FIG. 1 is shown. The cooling promotion area | region when the casting_mold | template shown in FIG. 1 and 2 is planarly viewed is shown.

[Glass plate manufacturing method]
The method for producing a glass plate of the present invention includes a bottom portion having a pair of opposing side walls that define the width of the glass plate and a surface (referred to as an upper surface) for forming one of two opposing main surfaces of the glass plate. In the mold, the molten glass flowing out from the orifice is continuously cast, and the glass cast along the both side walls is moved in one direction (referred to as a molding direction) from the upstream side to the downstream side, and the flat glass. A method comprising continuously forming a plate. In the method for producing a glass plate of the present invention, the molten glass is cast and formed into a flat plate shape from a position immediately below the orifice and a position immediately below the orifice when the upper surface is viewed in plan. It is characterized in that it is performed while locally cooling a region extending in the direction and having substantially the same width.

  As described above, the mold used in the manufacturing method of the present invention locally cools the position of the upper surface immediately below the orifice and the region having substantially the same width extending from the position immediately below the orifice toward the molding direction. There is no particular limitation as long as it can be performed.

The mold that can be used in the production method of the present invention is, for example,
The bottom of the mold has at least two through-holes inside, substantially orthogonal to the side wall and substantially parallel to the top surface,
One of the through holes is disposed at a position immediately below the orifice, and at least one of the remaining holes is disposed at a position downstream of the orifice immediately below,
The through hole has an opening on the side surface of the bottom portion connected to the outer side surface of the side wall,
Each through-hole has at least one discharge port for discharging a cooling medium on a side surface, and the size and / or the cooling medium discharged from the discharge port can flow out of the through-hole from the opening. A cooling medium supply pipe having a shape is disposed such that at least one of the discharge ports is located in the through hole;
The cooling medium supply pipes have the same number and the same shape of discharge ports,
The region is cooled by introducing a cooling medium into the cooling medium supply pipe disposed in the through hole, discharging the cooling medium from the discharge port, and cooling the upper surface in the vicinity of the discharge port. Can be things.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic view in plan view of a mold 1 which is an example of a mold used in the manufacturing method of the present invention. The mold 1 includes a pair of opposing side walls 11 and 11 ′ that define the width of the glass plate, and a bottom portion 13 having a surface (referred to as an upper surface) for molding one of the two opposing main surfaces of the glass plate. The molten glass flowing out from the orifice 3 is continuously cast into the mold 1. While the glass 2 cast along the both side walls 11 and 11 'is moved in one direction (referred to as a molding direction) from the upstream side to the downstream side, a flat glass plate is continuously formed. The glass 2 cast into the mold 1 is restricted to spread in the width direction by a pair of opposing side walls 11 and 11 ′, and is formed into a glass plate having a width equal to the interval between the pair of opposing side walls. By controlling the drawing speed of the glass plate and the flow rate of the molten glass flowing out from the orifice 3 so that the molten glass liquid level in the mold 1 is constant, a glass plate having a required thickness can be stably formed. Can do.

  The mold used in the present invention also has a stopper 12 corresponding to the dam part disclosed in Patent Document 1, and pulls out a glass plate molded in the molding direction as viewed from the stopper 12, that is, at the position facing the stopper 12. A mold opening (not shown) is provided.

  FIG. 2 illustrates a vertical cross section taken along line AA of FIG. The upper surface of the bottom 13 of the mold 1 is a flat and smooth surface. The bottom 13 is provided with a plurality of holes 14 extending in the width direction substantially parallel to each other. Local cooling of the bottom is facilitated by locally cooling the desired location on the inner surface of each hole. Although the number of holes shown in the figure is 6, the number of holes can be appropriately set within a range of 2 to 10, for example. Also, if necessary, the number of holes can exceed ten.

  As described above, casting of molten glass and forming into a flat plate shape extend in the forming direction from the position immediately below the orifice 3 and the position immediately below the orifice 3 when the upper surface of the bottom portion 13 is viewed in plan. The cooling promotion region having substantially the same width is performed while locally cooling. Therefore, for cooling the bottom portion 13, the cooling medium supply pipe 4 having a flow path for flowing a cooling medium therein and having a discharge port 41 for discharging the cooling medium on the side surface can be used. The cooling medium supply pipe 4 is inserted into the hole 14 in the bottom 13 of the mold 1 so that the discharge port 41 faces upward (in the direction of the upper surface of the bottom 13) (see FIG. 2). When the cooling medium is caused to flow through the cooling medium supply pipe 4, the cooling medium is ejected from the discharge port 41 and blown to the inner surface of the hole 14 facing the discharge port 41. The inner surface of the hole 14 to which the cooling medium is blown faces the upper surface of the bottom portion 13, and only the portion where the discharge port 41 is disposed is cooled, and the region including this portion becomes the cooling promotion region. However, strictly speaking, a region where the discharge ports in the bottom are distributed and a region where the cooling effect by the discharge of the cooling medium from the discharge port is caused by heat conduction correspond to the bottom cooling promotion region.

  The discharge port 41 provided in each cooling medium supply pipe 4 has the same shape, size, interval, arrangement, and number. By doing so, the cooling region can have substantially the same width toward the downstream. FIG. 1 shows, as an example, three cooling medium supply pipes 4 arranged in parallel so that the four discharge ports 41 face upward (in the direction of the upper surface of the bottom portion 13). 2 and 3 show a state in which three cooling medium supply pipes 4 are inserted into the three holes 14. The number of discharge ports 41 can be appropriately selected according to the cooling region. A plurality of cooling medium supply pipes 4 are inserted into the holes 14 of the mold bottom 13, and among the plurality of discharge openings provided in each cooling medium supply pipe, the central discharge opening coincides with the center in the mold width direction. Place each tube in The number and installation positions of the cooling medium supply pipes 4 can be appropriately determined in consideration of the size of the position of the cooling promotion region.

  As for the position of the cooling promotion region, if a position immediately below the orifice is a start position, a certain position from the position immediately below the orifice toward the molding direction is the final position. The final position is appropriately determined in consideration of the cooling state of the glass to be molded. Specifically, it is preferable that the position where the glass temperature is in the range of glass transition temperature Tg-100 ° C. to Tg + 100 ° C. is the final position. Further, until the lower surface temperature of the glass is cooled in the range of softening point to softening point −200 ° C., preferably in the range of softening point −30 ° C. to softening point −100 ° C., it is set so as to exist in the cooling promotion region. It is preferable from the viewpoint of preventing the thickness from becoming non-uniform due to the extent of not being fused to the mold and poor elongation, folding into the glass, and uneven unevenness and cracks on the glass surface. The thickness shape is determined based on the softening point, whereas the warped shape is determined based on the Tg standard. When the wall thickness is relatively large, warp is unlikely to occur because the strength of the sheet glass increases, and conversely, a temperature difference (particularly in the thickness direction) is likely to occur, so that cracks and cracks are likely to occur. In order to solve such a problem, it is preferable to finish the cooling of the sheet glass at a temperature higher than the glass transition temperature Tg.

  In addition, the width of the cooling promotion region is in the range of 5 to 40% of the width of the upper surface, and the wall thickness becomes uneven due to poor elongation to the end in the width direction, or the glass is bent into the glass. From the viewpoint of preventing uneven surface irregularities and cracks from occurring on the glass surface. The width of the cooling promotion region is preferably in the range of 10 to 30% of the width of the upper surface, and more preferably in the range of 10 to 25%.

  The production method of the present invention has a desired effect when the width of the glass plate to be formed is relatively wide, the thickness of the glass plate to be formed is relatively thin, and the flow rate of the molten glass flowing out from the orifice is relatively small. When the thickness of the glass plate to be molded is relatively thin, for example, the width is 100 mm or more, preferably 150 mm or more, more preferably in the range of 200 to 300 mm, the thickness is 6 to 30 mm, Preferably it is the range of 6-20 mm, Comprising: Width / thickness is the range of 3-50, Preferably it is 5-40, More preferably, it is the range of 10-40. The flow rate of the molten glass flowing out from the orifice can be, for example, in the range of 20 to 140 mL / min, preferably in the range of 30 to 120 mL / min, and more preferably in the range of 30 to 80 mL / min.

  FIG. 2 shows a state in which the cooling medium supply pipe 4 is inserted and arranged in the hole 14 of the bottom portion 13, but the cross-sectional shape of the cooling medium supply pipe 4 shown here is a semicircular shape, and the arc portion is downward. The flat portion where the discharge port 41 is provided faces upward. However, the cross-sectional shape of the cooling medium supply pipe 4 is not limited to a semicircular shape, and the discharge port 41 is provided and the cooling medium ejected from the discharge port 41 is formed between the cooling medium supply pipe 4 and the inner surface of the hole 14. There is no further limitation as long as it is a structure that discharges to the outside through a gap between them. In addition to the semi-circle, for example, a quadrangle or a triangle can be used.

  The cooling medium supplied from the outside through the inside of the cooling medium supply pipe 4 is discharged from the discharge port 41 toward the inner surface of the hole 14 of the bottom portion 13, strongly cooling the vicinity of the top portion of the inner surface of the hole 41, The gas is exhausted to the outside of the bottom through a gap formed between the cooling medium supply pipes 4. By adopting such a structure, the cooling strength in the vicinity of the discharge port can be locally and selectively increased in the portion of the bottom portion 13 where the hole 14 is provided. Further, the cooling of the portion provided with the hole at the bottom is significantly promoted compared to the portion without the hole. By using the mold 1 and the cooling medium supply pipe 4 described above and selecting the position of the hole 14 in the bottom portion 13 and the arrangement position of the discharge port 41, the cooling promotion region of the bottom portion 13 can be freely set. Further, the supply of the cooling medium to the cooling medium supply pipe 4 can be performed from one end side of the cooling medium supply pipe 4, but can also be performed from both end sides. When supplying the cooling medium from one end side, the other end can be blocked. In the case of performing from both end sides, it is appropriate to supply the cooling medium at the same pressure to both end sides from the viewpoint of uniformly cooling the left and right sides of the cooling promotion region. Alternatively, both ends of the cooling medium supply pipe 4 can be sealed, and a cooling medium supply pipe provided separately at the center can be connected to supply the cooling medium into the cooling medium supply pipe 4. In that case, the cooling medium supply pipe is also inserted into the hole 14 together with the cooling medium supply pipe 4.

  FIG. 3 shows a cooling promotion region in the mold shown in FIGS. However, the reject medium supply pipe 4 shown in FIG. The cooling promotion region includes a position immediately below the orifice and has substantially the same width toward the downstream. When the glass plate to be formed is relatively thin and the flow rate of the molten glass flowing out from the orifice is relatively small, the high-temperature molten glass flowing out from the orifice moves as a whole, that is, in the forming direction. However, the portion in contact with the high-temperature glass at the bottom has substantially the same width as it proceeds in the molding direction. Therefore, by setting this range as the cooling promotion region at the bottom, it is possible to accurately cool the portion in contact with the high temperature glass at the bottom, and to avoid excessively increasing the cooling strength outside the region of the cooling promotion region. In addition, it is possible to effectively prevent the folding of the glass, the unevenness of the tree pattern, and the generation of cracks.

  Furthermore, because it can selectively promote the cooling of the part that is heated intensely by contact with the glass, the temperature distribution of the entire bottom can be reduced, and the deformation of the bottom and the flatness of the glass plate accompanying this deformation are reduced. Such problems can be prevented.

  The region that promotes cooling of the upper surface should be symmetrically provided with respect to a virtual straight line that passes through the position immediately below the orifice and extends in the forming direction, so that the temperature distribution in the width direction of the glass plate is symmetrical with respect to the center position. This is preferable from the viewpoint that uniformity can be maintained. For this purpose, the arrangement of the discharge ports 41 is preferably symmetric with respect to the center line in the width direction of the mold, so that the bottom is cooled symmetrically with respect to the center line in the width direction. be able to. Casting of the molten glass is carried out by flowing the molten glass into the mold from an orifice disposed in the middle upper part between the pair of side walls of the mold. Therefore, since the temperature distribution in the width direction of the glass plate is basically symmetric with respect to the center position in the width direction, according to the above method, cooling can be performed without breaking the symmetry. In addition, the portion immediately below the orifice at the bottom can be additionally cooled strongly in a spot manner.

  The cooling medium is not particularly limited as long as it is a fluid for exchanging heat with the bottom. However, a gas, particularly air or nitrogen gas, is preferable because it is easy to obtain and the specific heat is small and the adjustment resolution is small.

  It is preferable that the cooling intensity in the cooling promotion region is linearly reflected in an increase or decrease in the supply amount of the cooling medium. To this end, in a mechanism using a cooling medium, when there are a plurality of cooling medium discharge ports, if the distance between the discharge port and the object to be cooled, i.e., the bottom, differs depending on the hole, the cooling medium may have the same flow rate. Since the effects differ, it is desirable to make the distance between the inner surface of the hole and the discharge port uniform in order to control the cooling strength by changing the size of the discharge port. For example, as shown in FIG. 2, the cross-sectional shape of each cooling medium supply pipe is aligned and the direction of the discharge port of each cooling medium supply pipe is aligned so that the direction of the discharge port does not change in each cooling medium supply pipe. Is preferred.

  Since the glass to be molded does not cause local deformation in the cross section in the width direction, it is preferable to cool the glass so as not to create a temperature sudden change portion (which affects the glass for a long time) at a specific position in the width direction. In particular, in the formation of a thin glass plate, the strength of the glass plate itself is small, and it is easy to deform due to the difference in cooling rate depending on the location. This will cause deformation, which is not preferable. In the present invention, when using a casting mold in which the cooling medium supply pipe 4 interspersed with the discharge ports 41 shown in FIGS. 1 to 3 is inserted into the holes 14 of the bottom portion 13, the bottom 13 is cooled by the cooling medium from the discharge ports 41. The portion can be set to a relatively small area on the upper surface, and the cooling medium can be reliably supplied only to the set position even at a small flow rate. Therefore, such a sudden temperature change portion is unlikely to occur, so that even a thin glass plate can be prevented from being deformed. Further, since the insertion direction of the cooling medium supply pipe 4 is perpendicular to the molding direction, the “time to receive influence (cooling promotion)” of the glass passing over the discharge port 41 is vacant in parallel to the molding direction. It is much shorter than the hole, and even if there is a sudden temperature change portion near the discharge port 41, the glass itself is unlikely to be greatly deformed.

  The glass plate formed by the method for producing a glass plate of the present invention is drawn out from the mold along the moving direction, and is transferred to the annealing furnace, for example, by a conveyor. In the process of passing through the annealing furnace, the glass plate is gradually cooled and moved out of the annealing furnace. The glass is moved in the mold by transferring the formed glass plate in the moving direction on the conveyor as described above. The glass plate is a continuous plate from the mold through the annealing furnace until it exits the annealing furnace. And it cut | disconnects in suitable length in the place which came out of the annealing furnace. In this way, plate-like glass can be obtained one after another from one glass plate. The glass plate thus obtained can be divided into glass pieces and used as a glass material for press molding. Details thereof will be described later.

  According to the method for producing a glass plate of the present invention, it is possible to melt the melted optical glass, flow out of a circular orifice, and continuously form it into a plate shape having a uniform thickness. In addition, since the molten glass that has flowed out at a low viscosity (high temperature) is cast into a mold having a flat bottom surface and a side wall parallel to each other across the bottom surface, and is rapidly quenched, it can be applied to optical glass that is easily devitrified. This forming method is suitable when the pulling amount (volume of molten glass per unit time flowing out from the orifice) is about 20 mL / min to 140 mL / min as described above.

  The main use of the glass plate produced by the method for producing a glass plate of the present invention is an intermediate for obtaining a glass material for press molding. That is, the manufactured glass plate can be cut into a dice-like piece by cutting vertically and horizontally as described later, and then subjected to a barrel polishing step for corner dropping and weight adjustment to be a press-molding material. The obtained material for press molding can be used as an optical component such as a lens by heating and softening and press molding, or by subjecting the press-molded article to grinding and polishing.

  In such applications, if the thickness of the glass plate material is not uniform, the cutting width must be changed in accordance with the thickness of the part in order to reduce the weight deviation of the small piece as the material for press molding. In addition, not only is it necessary to adjust the wheel interval extremely complicated, but if the cutting width cannot be corrected well, it will result in material loss and further weight adjustment by taking longer barrel polishing time. Because it comes out, the production efficiency is very bad and causes a cost increase, but according to the present invention, since the thickness of the glass plate can be made uniform, even if the glass plate is divided and cut with a constant cutting width, It is possible to suppress an increase in the weight deviation of the cut glass piece.

[Method of manufacturing glass material for press molding]
The present invention also relates to a method for producing a glass material for press molding for press molding by heating and softening. The manufacturing method of the glass material for press molding of this invention produces a glass plate by the method of the said invention, divides | segments the said glass plate, produces several glass piece (glass cut piece), Including processing. The cut piece processing is, for example, polishing processing. A glass piece is polished to obtain a glass material for press molding.

  Below, the specific aspect of the manufacturing method of the glass raw material for press molding of this invention is demonstrated.

  As described above, a diamond wheel, a wire saw, a grindstone, or the like was used as a method of dividing a glass piece (called a cut piece) from a glass plate obtained by cutting an end portion of a glass plate to be supplied. A cutting method, a method of applying a pressure to a glass plate so that a scribing process is performed on a part to be divided to form a marking line, and fracture is extended from the marking line to break the glass can be used. A glass material for press molding can be obtained by subjecting the glass pieces thus divided to polishing such as barrel polishing.

  According to the method for producing a glass plate of the present invention, a glass plate having a uniform thickness can be obtained with little difference in thickness between both ends and the center portion. The volume of the piece can be made to some extent, and the weight deviation of the cut piece can be suppressed without adjusting the cutting width for each cutting location. Therefore, it is possible to reduce the amount of glass that must be removed by barrel polishing in order to equalize the weight and volume of each cut piece, shorten the barrel polishing processing time, and save resources and energy. The cut piece is usually finished into a press-molding material by performing corner cutting and barrel polishing to further reduce the weight deviation. By gently removing the irregularities formed on the upper surface of the glass plate by the above polishing process, it is possible to obtain a glass material for press molding with a substantially smooth surface, but even if some irregularities remain, the stage of grinding and polishing the lens If it is the depth removed by this, there is no problem as a cut piece.

[Optical component manufacturing method]
The present invention includes a method for manufacturing an optical element, in which a glass optical element is manufactured through steps of heating, softening, and press-molding a glass material. This method is a method of producing a glass material for press molding by the method of the present invention, and heating, softening, and press molding the glass material.

The first aspect of the method for producing an optical component of the present invention is an optical component for obtaining an optical component by heating and press-molding the glass material for press molding produced by the method for producing a glass material for press molding of the present invention. It is a manufacturing method. In this embodiment, an optical component is obtained by so-called precision press molding. In precision press molding, the material for press molding is usually heated in a non-oxidizing atmosphere to a temperature at which a viscosity of 10 ⁵ to 10 ⁸ poise is reached, press-molded with a molding die, and the shape of the molding surface of the molding die is precisely glass. Transfer molding to. The press-molded product thus obtained has high shape accuracy and can be used as it is as an optical component such as a lens.

The second aspect of the method for producing an optical component of the present invention is to heat a glass material for press molding produced by the method for producing a glass material for press molding of the present invention, to produce a glass molded product by press molding, An optical component manufacturing method for obtaining an optical component by subjecting the glass molded product to grinding and / or polishing steps. In this aspect, an optical component is obtained through grinding and polishing after press molding. In such a manufacturing method, generally, a glass material for press molding is heated to a temperature at which a viscosity of about 10 ⁴ to 10 ⁶ poise is obtained in the atmosphere, and press-molded with a molding die. In press molding in the above temperature range, after obtaining a glass molded product that approximates the shape of the target glass article, grinding and polishing are performed, for example, for optical parts such as lenses that require high shape accuracy Can be finished.

  By such a method, optical components such as an aspherical lens, a spherical lens, a lens array, a microlens, a diffraction grating, and a prism can be manufactured with high productivity. If necessary, an optical multilayer film such as an antireflection film may be formed on the surface of the optical component.

[Method for producing thin glass]
The present invention includes a method for producing thin glass. In this method, a glass plate is produced by the method of the present invention, and a thin glass plate is produced from the produced glass plate through a process including lapping. The lapping process is a known processing method, and both main surfaces of the glass plate can be polished to obtain a flat sheet glass having a required thickness.

  Hereinafter, the present invention will be described in more detail with reference to examples.

Example 1
Using an optical glass of 1000 ° C. flowing out from the orifice at a flow rate of 60 mL / min, using the mold shown in FIG. 1, six cooling pipes each having five discharge ports at an 8 mm pitch are set to 0 mm from the orifice position toward the molding direction. , 30 mm, 60 mm, 0.3 MPa compressed air is supplied to the cooling pipe at 15 L / min, 10 L / min, and 5 L / min, respectively, to cool the bottom, and a glass with a molding width of 240 mm and a wall thickness of 15 mm When the plate was molded, a glass plate having a width direction thickness difference of 0.6 mm, a warp of 0.04 mm, and a tree pattern depth of 0.12 mm could be formed without folding.

Comparative Example 1
In order to form the glass plate using an apparatus as shown in FIG. 5b of Patent Document 1, 150 L / min of compressed air having a minimum cooling amount of 0.3 MPa to prevent fusion at the bottom. As a result, the elongation of the glass deteriorated near the side wall of the mold, resulting in a glass plate having a poor shape with a thickness difference of 1.5 mm in the width direction and a depth of 3.0 mm.

  The present invention is useful in the field of producing optical components such as lenses.

DESCRIPTION OF SYMBOLS 1 Mold 11,11 'Side wall 12 Stopper 13 Bottom part 14 Hole 2 Glass 3 Orifice 4 Cooling medium supply pipe 41 Discharge port

Claims (11)

It flows out of the orifice into a mold having a pair of opposing side walls that define the width of the glass plate and a bottom portion having a surface (hereinafter referred to as an upper surface) for molding one of the two opposing main surfaces of the glass plate. Molten glass is continuously cast, and the glass cast along the both side walls is continuously formed in one direction (hereinafter referred to as the molding direction) from the upstream side to the downstream side, and a flat glass plate is continuously formed. A method for producing a glass plate, comprising:
Casting of the molten glass and forming into a flat plate shape are substantially the same width extending in the forming direction from the position immediately below the orifice and the position immediately below the orifice when the upper surface is viewed in plan. A region having the following (hereinafter referred to as a cooling promotion region) while locally cooling , and
The local cooling of the cooling promotion region is
A cooling medium is introduced into a cooling medium supply pipe disposed in a through-hole provided substantially parallel to the upper surface inside the bottom of the mold, and provided at least on the side of the cooling medium supply pipe. Discharging the cooling medium from one discharge port and cooling the upper surface in the vicinity of the discharge port;
However, the upper surface in the vicinity of the discharge port is at least the upper surface in the cooling promotion region, and the cooling medium supply pipe allows the cooling medium discharged from the discharge port to flow out of the through hole through the through hole. A method for producing a glass plate, characterized by having possible dimensions and / or shapes . It flows out of the orifice into a mold having a pair of opposing side walls that define the width of the glass plate and a bottom portion having a surface (hereinafter referred to as an upper surface) for molding one of the two opposing main surfaces of the glass plate. Molten glass is continuously cast, and the glass cast along the both side walls is continuously formed in one direction (hereinafter referred to as the molding direction) from the upstream side to the downstream side, and a flat glass plate is continuously formed. A method for producing a glass plate, comprising:
Casting of the molten glass and forming into a flat plate shape are substantially the same width extending in the forming direction from the position immediately below the orifice and the position immediately below the orifice when the upper surface is viewed in plan. Performing while locally cooling a region having the following (hereinafter referred to as a cooling promotion region),
The bottom of the mold has at least two through-holes inside, substantially orthogonal to the side wall and substantially parallel to the top surface,
One of the through holes is disposed at a position immediately below the orifice, and at least one of the remaining holes is disposed at a position downstream of the orifice immediately below,
The through hole has an opening on the side surface of the bottom portion connected to the outer side surface of the side wall,
Each through-hole has at least one discharge port for discharging a cooling medium on a side surface, and the size and / or the cooling medium discharged from the discharge port can flow out of the through-hole from the opening. A cooling medium supply pipe having a shape is disposed such that at least one of the discharge ports is located in the through hole;
The cooling medium supply pipes have the same number and the same shape of discharge ports,
Cooling the area,
Introducing a cooling medium into the cooling medium supply pipe disposed in the through hole, discharging the cooling medium from the discharge port, and cooling the upper surface in the vicinity of the discharge port.
The manufacturing method of the said glass plate. 3. The manufacturing method according to claim 2 , wherein the number of the through holes and the cooling medium supply pipe is in a range of 2 to 10. The manufacturing method according to any one of claims 1 to 3 , wherein the flat glass plate has a width to thickness ratio in the range of 3 to 50. The width of the cooling promoting region, the production method according to any one of claims 1 to 4, 5 to 40% of the width of the top surface. The cooling promoting region passes a position directly below the orifice, to the imaginary straight line extending toward the molding direction, process for producing a glass plate according to any one of claims 1 to 5 having a symmetrical shape. The cooling promoting region from the position immediately below the orifice, the temperature of the glass toward the molding direction, more of claims 1-6 provided between the position to be in the range of the glass transition temperature Tg-100 ℃ ~Tg + 100 ℃ The manufacturing method of the glass plate of crab. The manufacturing method according to claim 1, wherein the cooling medium is a gas. In the manufacturing method of the glass material for press molding for heating, softening and press molding,
The glass plate was prepared by the method of any of claims 1-8, to prepare a plurality of glass cut pieces by dividing the glass plate, a manufacturing method of glass material for press molding for processing the cut pieces . In the method of manufacturing an optical element for producing a glass optical element through a process of heating, softening and press molding a glass material,
10. A method for producing an optical element, comprising producing a glass material for press molding by the method according to claim 9 , and heating, softening, and press molding the glass material. To prepare a glass plate by the method according to any one of claims 1-10, from the glass plate, the manufacturing method of the thin plate glass through a process to produce a thin glass plate that contains the slicing.

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