JP4078634B2 - Method for cooling high-temperature glass molding - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for cooling a high-temperature glass molded body such as an article formed from molten glass.
[0002]
[Prior art]
In the glass manufacturing industry, by melting glass material having a desired composition and forming it into a predetermined shape, it produces dimensional accuracy that satisfies the desired function, and manufactures various different size molded products with minute dimensions. There is a case. Alternatively, a desired precision shape may be realized by correcting the detailed surface shape while retaining the substantially entire outer shape of the molded product. In such a case, in order to respond quickly to market demands that require molded products of different dimensions, a glass molded body having a larger volume than the required glass product is molded or similar to a predetermined shape. A method has been used in which a shape having a predetermined size is formed in advance, and when a product having a predetermined size is required, the glass molded body is reheated to achieve a desired size and shape. Such a forming method is widely adopted as a method for manufacturing a glass product that requires high accuracy.
[0003]
For example, in the manufacture of an aspheric lens, a low-temperature press molding is performed in which a glass molded body having a shape as close as possible to the final shape is prepared in advance, and then a fine surface shape is re-formed as necessary. Moreover, in various thin tube glass, a high-precision glass thin tube is manufactured by producing tube glass as a glass molded body which becomes a base material in advance, and then reheating and drawing. A similar method is also employed for thin glass that requires a highly accurate surface state. Further, it is frequently performed in various glass products that a more complicated shape is realized by heating the ends of a glass molded body having two or more shapes after molding to fuse the glass.
[0004]
[Problems to be solved by the invention]
In recent years, the market size of optical related products has increased, and products satisfying various requirements have been supplied. Along with this, glass products that require higher precision dimensional tolerances have also been demanded. For this reason, it has become necessary to satisfy the requirements for higher dimensional accuracy with respect to the dimensional accuracy of products that employ precision reheating molding as described above. And in order to achieve it, it has become important how to cool efficiently without deforming the shape of the glass molded body formed into a predetermined dimension.
[0005]
For this reason, in the conventional cooling method of a glass molded body in a high temperature state, when the glass molded body is molded and cooled, the occurrence of minute deformation accompanying the volume change of the glass cannot be avoided, and it has heat resistance. In addition, contrivances such as using a metal mold using a special metal material having higher durability have been made. However, even when a special metal material is used, an excessive load is applied to both the mold and the glass, so that problems such as deterioration of the mold surface over time may occur. And in order to improve such a problem, it is important to cool the glass molded body in a high temperature state as rapidly as possible while minimizing the load applied to the mold.
[0006]
In addition, some glass molded bodies that are stretch-formed by reheating are required to have high dimensional accuracy. Therefore, a glass base material that is larger than the conventional glass preform is molded in advance and re-heated to stretch-mold. Therefore, it became necessary to realize high precision of glass products. In such a case, the glass base material that can be formed without any problem if the dimensions are the same as the conventional size, the temperature difference between the glass surface and the glass interior suddenly increases during the rapid cooling process as the size increases. There was also a problem that the phenomenon that it could not withstand the local temporary tensile stress generated on the surface of the glass base material due to the strain generated between the insides and that it exploded explosively due to thermal shock occurred.
[0007]
As a method for solving the problem of thermal shock destruction, there is a method of performing a slow cooling operation over time. However, since the slow cooling operation requires a certain amount of time, it is a process incompatible with rapid production as described above. In addition, this method cannot be substantially employed for glass materials that do not accept a slow cooling operation that takes a long time, such as a glass molded body made of crystallized glass or a glass molded body of a reheated colloid-colored glass body.
[0008]
In addition, as the size of the glass molded body increases, a portion of the glass molded body that is overcooled locally occurs locally, so adjusting the cooling rate of the glass molded body with the conventional continuous cooling method so that cracks do not occur. It becomes very difficult to cool rapidly. Therefore, a need has arisen for a new cooling method for rapidly cooling a large glass molded body requiring rapid cooling without causing cracks.
[0009]
The present invention substantially prevents deformation of the outer dimensions of a glass molded body used for re-molding after reheating and the like while maintaining the homogeneity of the glass when cooling from a high-temperature state immediately after molding. An object of the present invention is to propose a method for cooling a high-temperature glass molded body that realizes rapid cooling so that the glass molded body is free from defects such as cracks.
[0010]
[Means for Solving the Problems]
The inventors reviewed the conventional glass cooling method, and found a cooling method that enables rapid cooling safely without being destroyed by thermal shock during cooling of a high-temperature glass molded body.
[0011]
That is, the method for cooling a high-temperature glass molded body according to the present invention is a cooling method for cooling and solidifying a high-temperature glass molded body in a softened state immediately after continuous casting from high-temperature molten glass. A gas having a lower temperature than that is intermittently blown on the surface, and the contact time for contacting the gas to the high-temperature glass formed body is 0.1 to 300 seconds, the non-contact time is 0.1 to One cycle is 300 seconds, and this cycle is performed at least 10 times .
[0012]
The high-temperature glass molding here is a glass of a constituent component whose main component can be expressed by an oxide composition, and is a glass in which a glass raw material is melted at a melting temperature of at least 300 ° C., which is completely solidified In such a state, the difference from the ambient ambient temperature is several tens of degrees Celsius to several hundreds of degrees Celsius.
[0013]
Moreover, in the cooling method of this invention, the shape of the glass forming body shape | molded is not limited to a specific shape. That is, the shape of the glass molded body can be a polygonal columnar body, a cylindrical body, an annular body, a plate shape, a columnar body having a cross-section combining a plurality of shapes, and the top surface shape of the columnar body as necessary. It is also possible to adopt a case where the shape of the lower surface is different from that of the lower surface and the shape is gradually deformed on the way from the upper surface to the lower surface.
[0014]
Moreover, as for the glass cooling medium used with the cooling method of this invention, it is desirable that it is a gas or a liquid as what does not depend on the glass molded object to be cooled. And as long as it does not react with the glass surface that is the object to be cooled, it is possible to adopt various gases or liquids depending on the type of glass material, and it is a gas because it is easy to handle. It is more preferable. Also, there is nothing better than air in that it is cheaper than gas. However, when importance is attached to the prevention of oxidation of a metal member or the like constituting a cooling environment by contact with air, an inert gas such as carbon dioxide, nitrogen, or argon can be used. Moreover, it is also possible to use a mixed gas containing a predetermined amount of a plurality of gas components as required.
[0015]
The cooling medium that can be used most easily is air, and the next one that is used is an inert gas, but if further quenching is required and the conditions allow, the glass molded body that is to be cooled is turned into a gas. There is no problem even if a method of cooling by intermittently immersing, coating or spraying in a liquid cooling medium such as water, silicon oil, mercury, etc., set to a predetermined temperature having a large heat capacity.
[0016]
In addition, in order to achieve cooling while maintaining a complicated specific shape, a metal solid cooling medium equipped with a Peltier element or the like is intermittently brought into contact with the surface of the high-temperature glass molded body that is the object to be cooled, It is also possible to employ a method of cooling while preventing fine deformation of the surface of the high-temperature glass molded body accompanying cooling.
[0017]
The intermittent contact with the cooling medium, which is a feature of the cooling method of the present invention, causes an unnecessarily rapid generation of stress between the surface and the inside of the high-temperature glass molded body when the glass surface temperature is rapidly decreased. The present inventors have proposed as a means for preventing this. In this method, the surface of the high-temperature glass molding is intermittently or intermittently in contact with the cooling medium, so the glass cooling rate can be changed by variously changing the time of contact and the time of non-contact. It is possible to adjust precisely.
[0018]
And the intermittent cooling described here is based on the kind of the cooling medium and the temperature of the high-temperature glass molded body, but the contact time is 0.001 to 300 seconds, and the non-contact time is 0.001 to 300 seconds as one cycle. Cooling by performing this cycle at least 10 times, preferably 100 times or more. When gas or liquid is used as the cooling medium, this cycle is performed at least 10 times, preferably 100 times or more, with a contact time of 0.5 to 300 seconds and a non-contact time of 0.5 to 300 seconds as one cycle. This is realized. More preferably, when the cooling medium is a gas or a liquid, the contact time is 0.5 seconds to 60 seconds and the non-contact time is 0.5 seconds to 60 seconds, which is at least 50 times, preferably 100 times. To do more than once.
[0019]
Further, the intermittent contact with the cooling medium can be brought into contact with the high-temperature glass molded body while exchanging a plurality of types of cooling medium. In other words, it is possible to make it easy to adjust the cooling rate by blowing air and water vapor alternately and intermittently from nozzles, or by alternately blowing air heated to two or more set temperatures to the glass surface. It is. Moreover, when cooling by spraying, it cannot be overemphasized that the spray angle and flow velocity can be variously changed as needed. Furthermore, it is also possible to change the temperature of the cooling medium sequentially as the high-temperature glass molded body is cooled. Furthermore, efficient cooling can be reliably performed by operating according to a program in which various conditions such as contact time with the cooling medium, temperature setting, and in the case of gas, such as a flow rate and a blowing angle, are set in advance.
[0020]
In addition, by combining the automation of the stress measurement of the glass surface and the prediction of the maximum stress occurrence location depending on the shape of the glass molded body by simulation such as the finite element method, the boundary element method, and the control method of the cooling method of the present invention, It is possible to adjust the cooling rate corresponding to the change in the surface stress value of the high-temperature glass molded body at the position where the maximum surface stress generated during cooling is measured as needed. In addition, glass materials to be manufactured for the first time are not manufactured under ad hoc manufacturing conditions according to the cooling conditions predicted from the thermal expansion coefficient, Young's modulus, Poisson's ratio, etc. of the glass. It is possible to perform cooling under conditions that are immediately responsive to the above, and it is possible to realize high-speed cooling without fear of thermal shock damage, and it is possible to construct a manufacturing process in which the high-temperature glass molded body does not break during cooling.
[0021]
And the cooling method of this invention does not restrict | limit what kind of process is performed about the glass molded object after the cooling process by this invention. That is, if necessary, the heat treatment can be performed again, or another slow cooling operation can be performed. Further, even when sealed to other materials, cleaning with chemicals, immersion, machining such as polishing and cutting, film formation by vapor deposition, coating, and the like can be performed.
[0022]
In addition, the cooling method of the present invention does not hinder the parallel operation of the cooling operation of the present invention and other operations. That is, one end of the glass molded body may be cooled and the other end may be processed such as cutting. In addition, the present cooling method can be applied during the conveying operation of the glass molded body, and efficient cooling can be realized by using it together with other cooling operations for the high-temperature glass molded body. .
[0023]
Furthermore, the cooling method according to the present invention exhibits a particularly great effect when the size of the glass molded body is large, but does not preclude adoption for a small glass molded body. That is, regardless of the size of the glass molded body, ideal cooling of the glass molded body in a high temperature state can be realized by intermittently contacting the cooling medium with the high temperature glass molded body. Therefore, the cooling method according to the present invention can be applied, for example, from cooling a glass capillary having a diameter of 1 mm or less to cooling a columnar body having a size of 30 cm square or more.
[0024]
Furthermore, the method of the present invention exerts a great effect when used on a glass molded body used for re-molding after reheating, but it does not preclude adoption in other molding methods. Absent. The method of the present invention can also be used when directly forming a molded product having a product size, instead of adopting the re-molding method. That is, various methods such as casting molding method, downdraw method, dunner method, fusion method, blow molding, float molding, press molding method, rollout method, slot down method, velo method, stretch molding method, updraw method, redraw method, etc. It is also possible to apply this method.
[0025]
If the glass material that can use the method of the present invention is an oxide glass that can represent an inorganic oxide as a main component, it is a glass material having a plurality of component configurations, whether it is a single component glass. There is no particular limitation. Moreover, it can be applied to a glass having a special composition such as fluoride glass, fluorophosphate glass, chalcogenide glass, or nitride glass as required. However, when using the invention of the present invention with a gas blowing method for a glass composition of a special composition, it may be necessary to carry out in an environment such as a nitrogen atmosphere or a chlorofluorocarbon atmosphere. It is essential to change the gas composition according to the object.
[0026]
In addition, the cooling method of the present invention was invented as an operation method for cooling a molded body solidified from molten glass as described above, but it is widely used for cooling glass that has been heated to a high temperature and melted. Is possible. For example, as a typical example, cooling after hot forming of a glass tube, cooling after sealing two kinds of structures with various powdered glass, and heat fusion at the end of two or one kind of glass molded body It can be applied to subsequent cooling, cooling after press molding of spherical glass, cooling after heat sealing of various metal materials and glass, and the like.
[0027]
DETAILED DESCRIPTION OF THE INVENTION
The glass cooling method of the present invention will be described in detail with reference to specific examples.
[0028]
(Example 1) Crystallized glass used as a structural member for electronic parts may be used in applications related to light reception / emission of optical communication, optical connectors, etc., and requires extremely precise dimensional accuracy. Sometimes. In order to efficiently realize the molding of this glass product by the stretch molding method, a glass base material is required as a preformed body of a double glass ingot. In order to produce this glass base material, a glass molded body in a higher temperature state than the devitrification temperature range is cooled through a crystal nucleation temperature range lower than that. At that time, in order to lower the temperature of the entire glass in a shorter time than the time for which specific crystal nuclei are generated in the glass, it is necessary to employ a cooling method that is fast enough to achieve this. The present inventors applied the cooling method of the present invention to the cooling of the glass base material made of crystallized glass.
[0029]
First, as a method for producing a glass base material, a glass ingot which is a high-temperature glass molded body is formed by continuous casting. On the refractory roller for transporting the glass ingot immediately after forming, 10 nozzles each having a diameter of 2 cm are arranged in a perpendicular direction on each of the upper, lower and side surfaces, and heated to 100 ° C. in advance from the nozzles. Cooling air is intermittently blown over each surface of the glass ingot 300 times or more at intervals of 2 seconds under the condition of a wind speed of 3 m / sec. By performing this cooling, it was possible to realize sufficiently high-speed cooling in the crystal nucleation region, and it became possible to stretch-mold glass products having higher precision than conventional products.
[0030]
(Example 2) In the production of a non-linear optical glass molded body which is a functional material used as an optical component, semiconductor or metal colloidal particles having a level of several nanometers to several tens of nanometers in glass are subjected to heat treatment or treatment equivalent thereto. It needs to be generated. This process controls the size of the colloidal particles generated in the glass by reheating the glass product once quenched and formed, called the striking process, or by laser irradiation. In this case, rapid cooling is essential to the extent that no colloid is formed. As for the manufacturing method of this preform, the cooling method of this case is used in which air heated to 200 ° C. in advance is intermittently blown with respect to this glass molded body at the time of cooling immediately after casting. The The use of heated air means that it can prevent the glass molded body from being cooled too quickly locally, and the temperature control is more precisely controlled by using preheated air. There is an advantage that it becomes possible to do. And about this glass molded object, the air preheated at 60 degreeC with respect to the glass molded object with the apparatus similar to Example 1 is blown 200 times or more by the 5-second cycle from the substantially right angle at the wind speed of 5 m / sec. I'm wearing it. And it turned out that the glass preform which the colloidal particle which becomes a problem in the glass after cooling does not precipitate is obtained.
[0031]
( Reference Example 1 ) For the low-temperature press molding of glass moldings that mold micro precision glass lenses used as optical components, this is a rapid cooling method for molds equipped with Peltier elements and heated glass lenses. The method is adopted. That is, in an optical component that requires high-precision dimensions such as an aspheric lens, the influence exerted on the optical characteristics of the final product due to minute deformation of the surface of the glass molded body is significant. For this reason, various attempts have been made on the material of a press mold, glass material, and the like. In particular, as a viscosity characteristic of glass, from the viewpoint that it is easy to prevent deformation of the glass molded body surface due to “sinks” generated on the surface of the glass molded body, it has a property that is highly temperature dependent due to viscosity, a so-called “short” property. The material is preferred. However, at the same time, rapid cooling that does not affect the optical properties is required for low-temperature press molding. This is desirable from the viewpoint of improving the durability of the mold used in addition to the above-described prevention of deformation of the glass molded body surface. The cooling method of this reference example is for the cooling of the surface of the glass molded body after the pressing, by performing contact between the mold and the surface of the glass molded body intermittently, so that the desired optical function can be achieved without deformation of the glass molded body. Adopted to have. In practice, the target glass aspherical lens can be obtained by bringing the surface of the mold whose temperature is adjusted to 50 ° C. into contact with the surface of the high-temperature glass molded body more than 2000 times in a 0.1 second cycle. .
[0032]
( Reference Example 2 ) The plate glass used for the display device is one of the glass that is redraw molded in the same manner as in Example 1, but the preform has a cross-sectional shape of thickness 10 mm × width 1000 mm. When cooled rapidly during molding, it may be damaged by thermal shock. Therefore, it became possible to prevent cracking by adopting the cooling method of the present case. FIG. 1 is a cross-sectional view for explaining the case where the cooling method of this reference example is applied to a forming part of this plate glass. The molten glass G that has been sufficiently homogenized is formed into a plate shape by the downdraw method. Here, the nozzle 10 having a rectangular opening of 3 mm × 1000 mm is installed in a direction perpendicular to the front and back surfaces of the glass plate immediately after forming. At the time of glass molding, the generation of cracks can be prevented by blowing air heated at a wind speed of 3 m / sec. From a temperature of 100 ° C. to 50 ° C. in a state where the temperature is gradually lowered by 500 times in a 3-second cycle. It became possible.
[0033]
【The invention's effect】
According to the cooling method of the present invention, it is possible to precisely adjust the cooling rate of the glass molded body in a high temperature state, so that no unnecessary crystallized precipitates are generated in the glass molded body, and glass molding is performed during cooling. It is possible to rapidly cool a glass molded body in a high temperature state without causing problems such as cracking of the glass due to significant increase in distortion generated in the body, and to efficiently produce high-quality glass products. Is possible.
[Brief description of the drawings]
1 is a partial cross-sectional view of a method for cooling a high-temperature glass molded body of Reference Example 2. FIG.

Claims (4)

A cooling method of cooling and solidifying a high-temperature glass molded body in a softened state immediately after continuous casting from a high-temperature molten glass,
A low-temperature gas is intermittently blown onto the surface of the high-temperature glass molded body, and the contact time for intermittently contacting the gas with the high-temperature glass molded body is 0.1 to 300 seconds, and the non-contact time. The cooling method for a high-temperature glass molded body is characterized in that this cycle is carried out at least 10 times with 0.1 to 300 seconds as one cycle . The method for cooling a high-temperature glass molded body according to claim 1 , wherein the gas is one or more of air, inert gas, nitrogen, and carbon dioxide.   The method for cooling a high-temperature glass molded body according to claim 1 or 2, wherein the temperature of the gas brought into contact with the high-temperature glass molded body is room temperature or higher.   The method for cooling a high-temperature glass molded body according to any one of claims 1 to 3, wherein the cooled high-temperature glass molded body is made of crystallized glass.

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