HK1178875B

HK1178875B - Consecutive molding method for crystallized glass and device thereof

Info

Publication number: HK1178875B
Application number: HK13105836.2A
Authority: HK
Inventors: 许国铨; 姜岩浜; 曲超
Original assignee: 湖州大享玻璃制品有限公司; 大享容器工业股份有限公司
Priority date: 2011-05-16
Filing date: 2013-05-16
Publication date: 2015-12-18

Description

Method and apparatus for continuously forming crystallized glass

Technical Field

The present invention relates to a method for continuously forming crystallized glass and an apparatus for continuously forming crystallized glass.

Background

In general, crystallized glass is obtained by melting a glass raw material containing a crystal nucleus-forming component, forming the molten glass into a plate-like shape to obtain a crystalline glass, and applying a crystallization heat treatment to the crystalline glass. To date, a manufacturing method and a manufacturing apparatus have been developed to improve the producibility of crystallized glass. For example, a continuous forming apparatus for crystallized glass is disclosed (for example, see japanese patent laid-open publication No. 2005-41726), which can continuously perform a series of steps from melting, forming, crystallizing, annealing, and cutting of a glass raw material.

In a method for manufacturing crystallized glass by continuously melting, forming, crystallizing, annealing, and cutting a glass raw material, a crystallization step is a rate determining step. The reason for this is that: the heat treatment for crystallization requires a multistage temperature treatment that does not affect the glass sheet by a rapid temperature change in order to suppress the occurrence of waviness, deformation, cracking, and cracking in the glass sheet.

For example, in a continuous forming apparatus described in japanese patent application laid-open No. 2005-41726, the crystallization apparatus includes: a heat-insulating region for holding the belt-like plate glass at a temperature near a glass transition temperature; in the 1 st heating area, the temperature of the strip plate glass is raised to the nucleation temperature; a nucleus formation region in which the band-shaped plate glass is kept at a nucleus formation temperature; a2 nd heating area for heating the strip plate glass to the crystal growth temperature; a crystal growth region for holding the belt-shaped plate glass at a crystal growth temperature; and an annealing zone for removing the deformation of the belt-shaped crystallized glass plate.

Disclosure of Invention

In the continuous forming method of crystallized glass, if the heat treatment step for crystallization can be improved, the heat treatment time required for crystallization is shortened, and the productivity is improved.

The invention aims to provide a method for continuously forming crystallized glass, which can shorten the heat treatment time required by crystallization of strip plate glass.

Further, the present invention has an object to provide a continuous forming apparatus for crystallized glass, which can shorten a heat treatment region required for crystallization of a ribbon-shaped plate glass.

The inventor finds that: in the continuous forming method of crystallized glass, the crystallized glass can be continuously formed by starting the heat treatment from the temperature at which crystal nuclei are formed without performing the heat treatment step of holding the band-shaped plate glass obtained by the rolling forming at the temperature near the glass transition temperature.

Specific means for solving the foregoing problems are as follows.

The present invention provides a method for continuously forming crystallized glass, comprising:

a melting step of melting a glass raw material to obtain molten glass;

a forming step of rolling and forming the molten glass into a belt shape to obtain belt-shaped plate glass;

a crystallization step of heat-treating the belt-shaped plate glass to crystallize the plate glass to obtain a belt-shaped crystallized glass plate; and

a cutting step of cutting the belt-shaped crystallized glass plate;

and the crystallization step has:

a crystal nucleus formation step of putting the ribbon-shaped plate glass obtained in the forming step into an environment at a crystal nucleus formation temperature, maintaining the ribbon-shaped plate glass at the crystal nucleus formation temperature, and forming crystal nuclei in the ribbon-shaped plate glass;

a temperature raising step of raising the temperature of the band-shaped plate glass forming the crystal nucleus to a crystal growth temperature;

a crystal growth step of maintaining the band-shaped plate glass forming the crystal nucleus at a crystal growth temperature and crystallizing the band-shaped plate glass into a band-shaped crystallized glass plate; and

and a slow cooling step of gradually cooling the belt-shaped crystallized glass plate.

Preferably, in the above method, between the melting step and the forming step, the continuous forming method further includes:

an adjustment step of adjusting the uniformity, viscosity, and liquid level of the molten glass obtained by the melting step; and

and a devitrification prevention step of preventing devitrification of the molten glass after the adjustment step.

The present invention also provides a continuous forming apparatus for crystallized glass, comprising:

a melting device that melts a glass raw material to obtain molten glass;

a forming device for rolling and forming the molten glass into a belt shape to obtain belt-shaped plate glass;

a crystallization device for obtaining a belt-shaped crystallized glass plate by heat-treating the belt-shaped plate glass and crystallizing the belt-shaped plate glass; and

a cutting device for cutting the belt-shaped crystallized glass plate;

and the crystallization apparatus has:

a crystal nucleus formation region for forming crystal nuclei in the band-shaped plate glass by holding the band-shaped plate glass obtained by the forming apparatus in an environment at a crystal nucleus formation temperature and maintaining the band-shaped plate glass at the crystal nucleus formation temperature;

a temperature raising region for raising the temperature of the band-shaped plate glass forming the crystal nucleus to a crystal growth temperature;

a crystal growth region for crystallizing the band-shaped plate glass forming the crystal nucleus into a band-shaped crystallized glass plate while maintaining the band-shaped plate glass at a crystal growth temperature; and

and a slow cooling region for gradually cooling the belt-shaped crystallized glass plate.

Preferably, in the above apparatus, between the melting apparatus and the forming apparatus, the continuous forming apparatus further includes:

an adjusting device for adjusting the uniformity, viscosity and liquid level of the molten glass obtained by the melting device; and

and a devitrification prevention device for preventing devitrification of the molten glass flowing out from the regulating device.

According to the present invention, a method for continuously forming crystallized glass can be provided, which can shorten the heat treatment time required for crystallizing a ribbon-shaped plate glass.

Further, according to the present invention, it is possible to provide a continuous forming apparatus for crystallized glass, which can shorten a heat treatment region required for crystallization of a ribbon-shaped plate glass.

Drawings

FIG. 1 is a schematic view showing an embodiment of an apparatus for continuously forming crystallized glass according to the present invention.

FIG. 2A and FIG. 2B are graphs showing the gradient of the ambient temperature in the crystallization apparatus in each of the embodiments of the continuous forming apparatus for crystallized glass of the present invention.

[ description of element symbols ]

11 melting apparatus

12 adjustment device

12a liquid level control apparatus

12b mixing equipment (muddler)

12c heating element

12d thermocouple

13 anti-devitrification device

13a Heat preservation equipment (Heat preservation refractory)

13b lip brick

13c support

13d heating element

14 roll forming equipment

14a upper roll shaft

14b lower side roller shaft

14c cooling water tank

15 handling equipment

16 pressing roll shaft

17 crystallizing equipment (roll type tunnel kiln)

18 heating element

19 conveying roll shaft

20 thermocouple

23 nucleation region

24 heating area

25 crystal growth region

26 slow cooling area

27 cutting device

28 stirring device

A belt-shaped plate glass

B belt-shaped crystallized glass plate

C-cut crystallized glass plate

Detailed Description

The first invention is a method for continuously forming crystallized glass, comprising:

a melting step of melting a glass raw material to obtain molten glass;

a cutting step of cutting the belt-shaped crystallized glass plate;

and the crystallization step has:

a crystal nucleus formation step of putting the ribbon-shaped plate glass obtained in the forming step into an environment of a crystal nucleus formation temperature and maintaining the ribbon-shaped plate glass at the crystal nucleus formation temperature to form crystal nuclei in the ribbon-shaped plate glass;

The method for continuously forming crystallized glass of the present invention can continuously perform a series of steps from melting, forming, crystallizing, annealing, and cutting of a glass raw material by sequentially performing the melting step, the forming step, the crystallizing step, and the cutting step.

The melting step is as follows: and a step of obtaining molten glass by melting the glass raw material by heating. The heating temperature is not particularly limited as long as the glass raw material is melted. The melting step may comprise: in the process of preparing the glass raw material before melting the glass raw material, it is preferable to continuously prepare the glass raw material until the glass raw material is melted from the viewpoint of productivity.

The forming steps are as follows: and a step of rolling and forming the molten glass into a belt shape to obtain a belt-shaped plate glass. The roll forming method may be a known method, and for example, a roll forming method of rolling a molten glass by a pair of rolls may be used.

The crystallization step is as follows: and a step of obtaining a belt-shaped crystallized glass plate by heat-treating the belt-shaped plate glass and crystallizing the glass. The crystallization step will be described in detail below.

The cutting-off step is as follows: and a step of cutting the belt-shaped crystallized glass plate into a desired length. The cutting method may be a known method, and for example, a cutting method using a diamond cutter or a cutting method using a water jet cutter may be used.

The crystallization step comprises: a crystal nucleus formation step of putting the ribbon-shaped plate glass obtained in the forming step into an environment of a crystal nucleus formation temperature and maintaining the ribbon-shaped plate glass at the crystal nucleus formation temperature to form crystal nuclei in the ribbon-shaped plate glass; a temperature raising step of raising the temperature of the band-shaped plate glass forming the crystal nucleus to a crystal growth temperature; a crystal growth step of maintaining the band-shaped plate glass forming the crystal nucleus at a crystal growth temperature and crystallizing the band-shaped plate glass into a band-shaped crystallized glass plate; and a slow cooling step of gradually cooling the belt-shaped crystallized glass plate.

The crystallization step is a heat treatment process for crystallizing the band plate glass, and is started by putting the band plate glass into an environment at a crystal nucleus formation temperature. That is, the present invention does not include the heat treatment step of maintaining the temperature near the glass transition temperature, which is included in the known continuous forming method.

In the present invention, the vicinity of the glass transition temperature means a range within. + -. 10 ℃ of the glass transition temperature.

The nucleation step is as follows: and a step of directly putting the ribbon-shaped plate glass obtained in the forming step into an environment at a crystal nucleus formation temperature, maintaining the ribbon-shaped plate glass at the crystal nucleus formation temperature, and forming crystal nuclei in the ribbon-shaped plate glass. The band-shaped plate glass put into the environment of the nucleation temperature is continuously heated from the temperature between the forming step and the crystallization step to the nucleation temperature and kept at the nucleation temperature to form crystal nuclei.

The temperature for forming the crystal nuclei may be any temperature at which the crystal nuclei can be formed. The nucleation temperature is suitably selected in accordance with the glass composition. Further, depending on the glass composition, it is possible to simultaneously perform nucleation and crystal growth of the ribbon plate glass, and crystals can also be grown at the nucleation temperature.

The nucleation temperature is preferably a substantially constant temperature.

The holding temperature and holding time of the nucleation step are not particularly limited, and may be appropriately selected from: conditions capable of sufficiently forming a desired crystal nucleus.

The holding temperature in the crystal nucleus formation step is preferably set to the crystal nucleus formation temperature in the known crystallized glass production method or a temperature in the vicinity thereof. The nucleation step is preferably maintained at a temperature of 600 ℃ to 1000 ℃, more preferably 650 ℃ to 900 ℃, still more preferably 700 ℃ to 850 ℃, and is preferably maintained at a substantially constant temperature (less than + -5 ℃).

The retention time of the nucleation step may be a time required for nucleation in a known crystallized glass production method. The retention time of the nucleation step is usually about 10 minutes to 3 hours.

The nucleation is facilitated by adding a nucleation component such as TiO2, ZrO2, P2O5, F2, etc. to the glass raw material in advance.

The temperature rising step is as follows: and raising the temperature of the environment around the strip-shaped plate glass from the temperature capable of forming crystal nuclei to the temperature capable of growing crystals. In the temperature raising step, the temperature gradient of the temperature raising is not particularly limited and is selected in accordance with the glass composition or size of the belt-shaped plate glass. For example, the temperature is preferably raised at a rate of 0.5 to 10 ℃/min. Of course, the lower the temperature rise rate, the less likely waviness, deformation, cracking, and cracking will occur in the strip glass sheet.

The crystal growth steps are as follows: and a step of maintaining the ambient temperature around the belt-shaped plate glass at a temperature at which crystals can grow (preferably, a temperature at which crystals can grow almost constantly), and growing the crystals to form a belt-shaped crystallized glass plate.

The holding temperature and holding time in the crystal growth step are not particularly limited, and may be appropriately selected from: conditions capable of sufficiently growing desired crystals.

The holding temperature in the crystal growth step is preferably set to a temperature at or near the crystal growth temperature in the known crystallized glass production method. The temperature of the crystal growth step is usually 750 ℃ to 1100 ℃, and the ideal state is 800 ℃ to 1000 ℃, and the ideal state is 850 ℃ to 950 ℃, and the temperature is almost kept constant (below +/-5 ℃).

The holding time of the crystal growth step may be: the time required for crystal growth in the crystallized glass production method is known. The holding time in the crystal growth step is usually about 10 minutes to 3 hours.

The slow cooling step comprises the following steps: and gradually cooling the belt-shaped crystallized glass plate to remove the permanent strain from the belt-shaped crystallized glass plate and simultaneously form the homogenized glass. In the present invention, slow cooling means cooling at a cooling rate capable of eliminating the degree of deformation. In the slow cooling step, the temperature gradient of cooling is not particularly limited and is selected in accordance with the glass composition or size of the ribbon glass sheet. For example, the cooling is preferably performed at a cooling rate of 0.5 ℃/min to 20 ℃/min. Of course, the slower the cooling rate, the less permanent deformation.

The present invention is to directly supply a band-shaped plate glass obtained by rolling molding to a crystal nucleus formation temperature without a heat treatment step in which the band-shaped plate glass is supposed to be kept at a temperature near the glass transition temperature in the known crystallized glass continuous molding method. Therefore, the entire treatment time of the crystallization step can be shortened, and the time of the temperature raising step and the slow cooling step can be lengthened without lengthening the entire treatment time of the crystallization step. When the temperature raising step time is made longer, the temperature gradient of the temperature raising can be made gentle, and therefore, waviness, deformation, breakage, and cracks are less likely to occur in the ribbon-shaped sheet glass. Further, when the slow cooling step time is made longer, the temperature gradient of the slow cooling can be made gentle, and the temperature gradient of the slow cooling can be made into a plurality of stages, so that the deformation of the ribbon-shaped crystallized glass plate formed by crystallization can be effectively removed. As a result, the crystallized glass obtained by the present invention was excellent in flatness, impact strength and the like.

The continuous forming method of crystallized glass of the present invention is preferably as follows: between the melting step and the forming step, further comprising:

an adjustment step of adjusting the uniformity, viscosity and liquid level of the molten glass obtained by the melting step; and

The present invention homogenizes the molten glass by including the adjusting step and the devitrification prevention step, controls the viscosity of the molten glass, prevents devitrification of the molten glass, and can supply the molten glass to the forming step at a constant flow rate.

The adjusting step is composed of stirring the molten glass to be uniform, heating the molten glass to control viscosity, and controlling the liquid level of the molten glass. Controlling the liquid level of the molten glass according to: the liquid level of the molten glass introduced from the melting step to the adjusting step is detected, and a signal corresponding to the amount of change in the liquid level is fed back to a glass raw material charging facility into which the glass raw material is charged, and the amount of the raw material charged into the melting facility is corrected.

The anti-devitrification step is preferably carried out in the following manner: comprises heat-insulating molten glass and heat-melting glass. The molten glass before the introduction into the forming step is kept at a predetermined temperature by heat-insulating and heating, thereby preventing devitrification of the molten glass.

The crystallized glass plate obtained through the above-described steps may be subjected to a polishing step of polishing the surface for adjusting the thickness, surface finishing, or the like, or a processing step of processing the crystallized glass plate into a predetermined size or shape, as required.

The method for continuously forming crystallized glass of the present invention is suitable for the apparatus for continuously forming crystallized glass of the present invention described below.

The second invention is a continuous forming apparatus for crystallized glass, comprising:

a melting device that melts a glass raw material to obtain molten glass;

a cutting device for cutting the belt-shaped crystallized glass plate;

and the crystallization apparatus has:

a crystal nucleus forming region for forming crystal nuclei in the band-shaped plate glass by holding the band-shaped plate glass obtained by the forming apparatus in an environment of a crystal nucleus forming temperature and maintaining the band-shaped plate glass at the crystal nucleus forming temperature;

The continuous forming apparatus for crystallized glass of the present invention comprises the melting apparatus, the forming apparatus, the crystallizing apparatus, and the cutting apparatus in this order, and thus a series of steps from melting, forming, crystallizing, annealing, and cutting of a glass raw material can be continuously performed.

The melting equipment is as follows: an apparatus for obtaining molten glass by heating and melting glass raw materials. The melting apparatus may be constituted by a furnace having a heating mechanism necessary for melting the glass raw material, and various known glass melting furnaces may be used. The melting apparatus may include a preparation mechanism for preparing the glass raw material before the heating mechanism necessary for melting the glass raw material.

The forming equipment comprises: and rolling the molten glass into a belt shape to obtain belt-shaped plate glass. In the molding apparatus, the method of rolling molding is not particularly limited, and for example, it may be a roll forming method in which rolling processing is performed by a set of rolls.

The crystallization equipment comprises: and a device for obtaining a belt-shaped crystallized glass plate by heat-treating the belt-shaped plate glass and crystallizing the glass. The crystallization apparatus will be described in detail below.

The cutting equipment comprises: an apparatus for cutting a belt-shaped crystallized glass plate into a predetermined length. In this cutting apparatus, the cutting method may be a known method, and may be, for example, cutting with a diamond cutter or cutting with a water jet cutter.

The crystallization apparatus comprises:

The crystallization apparatus has the nucleation region at the most upstream side, and does not have a heat treatment region maintained at a temperature near the glass transition temperature, which is provided in the known continuous forming apparatus.

The nucleation region is a region in which the ribbon-shaped plate glass obtained by the forming apparatus is accommodated in an environment of a nucleation temperature and is maintained at the nucleation temperature, and crystal nuclei are formed in the ribbon-shaped plate glass. The band-shaped plate glass accommodated in the crystal nucleus formation region is continuously adjusted to the crystal nucleus formation temperature from the temperature when it is positioned between the forming apparatus and the crystallization apparatus while passing through the crystal nucleus formation region, and is maintained at the crystal nucleus formation temperature, thereby forming crystal nuclei.

The temperature for forming the crystal nuclei may be any temperature at which the crystal nuclei can be formed. The nucleation temperature is selected appropriately according to the glass composition. Further, depending on the glass composition, nucleation and crystal growth of some ribbon-shaped plate glasses proceed simultaneously, and even if crystals grow in the nucleation regions, there is no relation.

The nucleation region is preferably maintained at a substantially constant temperature.

The ambient temperature of the nucleation region is not particularly limited, and may be appropriately selected from: a temperature at which a desired crystal nucleus can be formed sufficiently. The ambient temperature of the nucleation region is preferably set to the nucleation temperature in the conventional method for producing crystallized glass or to the vicinity thereof. The environment temperature of the nucleation zone is usually 600-1000 deg.C, and the ideal state is 650-900 deg.C, and the ideal state is 700-850 deg.C, and the temperature is almost kept constant (below + -5 deg.C).

The length of the crystal nucleus formation region and the speed of conveyance of the band-shaped plate glass in the crystal nucleus formation region are not particularly limited, and conditions may be appropriately selected so that a sufficient time for forming desired crystal nuclei can be secured. This time may be a time required for nucleation in a known method for producing crystallized glass, and is usually about 10 minutes to 3 hours.

Further, the speed of transporting the ribbon-shaped sheet glass in the nucleation region can be appropriately selected in accordance with the throughput of the melting apparatus or/and the forming apparatus. Then, when the carrying speed of the belt-shaped plate glass in the crystal nucleus formation region is slow, the length of the crystal nucleus formation region can be shortened according to the carrying speed, and when the carrying speed of the belt-shaped plate glass in the crystal nucleus formation region is fast, the length of the crystal nucleus formation region can be lengthened according to the carrying speed.

The temperature raising region is a region in which the ambient temperature around the belt-shaped plate glass is raised from a temperature at which crystal nuclei can be formed to a temperature at which crystals can grow. In the temperature raising region, it is preferable that a predetermined temperature gradient is set, and the temperature of the belt-shaped plate glass is gradually raised as the belt-shaped plate glass is conveyed toward the outlet of the crystallization apparatus. In the heating region, the temperature gradient in the region is not particularly limited and is selected in accordance with the glass composition or size of the ribbon plate glass. Of course, the gentler the temperature gradient, the less likely it is to cause waviness, deformation, cracking, and cracks in the ribbon glass sheet.

The crystal growth region is a region in which the ambient temperature in the region is maintained at a temperature at which crystals can grow (preferably, the temperature is substantially constant). The ribbon-shaped plate glass is grown into a ribbon-shaped crystallized glass while passing through the crystal growth region.

The ambient temperature of the crystal growth region is not particularly limited, and may be appropriately selected from: a temperature at which desired crystals can be sufficiently grown. The ambient temperature of the crystal growth region is preferably set to the crystal growth temperature in the known method for producing crystallized glass or to the vicinity thereof. The ambient temperature of the crystal growth zone is generally 750 ℃ to 1100 ℃, and more preferably 800 ℃ to 1000 ℃, and still more preferably 850 ℃ to 950 ℃, and the temperature is preferably kept almost constant (less than +/-5 ℃).

The length of the crystal growth zone and the speed of conveying the ribbon-shaped plate glass in the crystal growth zone are not particularly limited, and conditions may be appropriately selected so that a sufficient time for growing a desired crystal can be secured. This time is a time required for crystal growth in a known method for producing crystallized glass, and is usually about 10 minutes to 3 hours.

Further, the speed of conveying the ribbon-shaped sheet glass in the crystal growth zone can be appropriately selected in accordance with the throughput of the melting apparatus or/and the forming apparatus. When the conveyance speed of the ribbon-shaped plate glass in the crystal growth region is low, the length of the crystal growth region can be shortened in accordance with the conveyance speed, and when the conveyance speed of the ribbon-shaped plate glass in the crystal growth region is high, the length of the crystal growth region can be lengthened in accordance with the conveyance speed.

The slow cooling area is as follows: in order to remove permanent strain from the belt-shaped crystallized glass plate and form a uniform glass, the area of the belt-shaped crystallized glass plate is gradually cooled. In the slow cooling region, the temperature gradient in the region is not particularly limited and is selected in accordance with the glass composition or the size of the ribbon glass. Of course, the slower the temperature gradient, the less permanent deformation.

The present invention omits a heat treatment region which is considered to be necessary in a conventional crystallized glass continuous forming device to keep a strip-shaped plate glass at a temperature near a glass transition temperature, and the strip-shaped plate glass drawn out from the forming device is directly accommodated at a crystal nucleus formation temperature. Therefore, the entire length of the crystallization apparatus can be shortened, or the lengths of the heating region and the slow cooling region can be lengthened without lengthening the entire length of the crystallization apparatus. When the temperature rise region is made longer, the temperature gradient of the temperature rise can be made gentle, and therefore, waviness, deformation, cracking, and cracks are less likely to occur in the belt-shaped plate glass. Further, when the slow cooling region is made longer, the temperature gradient of the slow cooling can be made gentle, and the temperature gradient of the slow cooling can be made into a plurality of stages, so that the deformation of the crystallized glass sheet in the form of a ribbon can be effectively removed. As a result, the crystallized glass obtained by the present invention has excellent impact strength.

In a preferred aspect of the continuous forming apparatus for crystallized glass according to the present invention, the melting apparatus further comprises:

and a devitrification preventing device for preventing devitrification of the molten glass flowing out from the regulating device.

The invention homogenizes the molten glass by the adjusting device and the devitrification prevention device, controls the viscosity of the molten glass, prevents the molten glass from devitrification, and can supply the molten glass to the forming device at a predetermined flow rate.

The adjusting means is composed of a homogenizing means for homogenizing the molten glass, a viscosity control means for controlling the viscosity of the molten glass, and a liquid level control means for controlling the liquid level of the molten glass. The homogenizing apparatus is provided with a device for stirring molten glass. The viscosity control device is provided with a heating device for heating the molten glass. The liquid level control means detects the liquid level of the molten glass introduced from the melting means to the adjusting means, and feeds back a signal corresponding to the amount of change in the liquid level to glass raw material charging means into which the glass raw material is charged, thereby correcting the amount of raw material charged into the melting means. Since the liquid level control means can measure the height of the liquid level of the molten glass passing through the adjusting means and correct the amount of the raw material to be charged, the thickness of the strip-shaped sheet glass formed by the forming means can be controlled to a predetermined thickness. Therefore, the crystallized glass can be automatically manufactured in a large scale, and the stabilization of the quality can be planned, and the program management can be easily performed.

The anti-devitrification device has the ideal mode that: comprises a heat-insulating device for insulating molten glass and a heating device for heating the molten glass. The molten glass before being introduced into the forming apparatus is maintained at a predetermined temperature by the heat-insulating apparatus and the heating by the heating apparatus, thereby preventing the molten glass from devitrifying.

The continuous forming apparatus for crystallized glass of the present invention is preferably as follows: between the forming apparatus and the crystallizing apparatus, there is further provided a pressing roller for pressing the belt-like plate glass output from the forming apparatus. The surface of the belt-like sheet glass discharged from the forming apparatus is formed into a flat roll surface by the press roll. By providing the press roll shaft, the belt-shaped plate glass formed by the forming apparatus can be flattened and introduced into the crystallizing apparatus.

The continuous forming equipment for crystallized glass of the present invention is an ideal crystallized glass manufacturing equipment widely used for manufacturing crystallized glass such as substrates for high-tech products such as substrates for color filters, substrates for image sensing, etc., brackets for electronic component firing, electromagnetic oven panels, optical components, microwave oven frames, window glass for fire doors, front glass for petroleum stoves, wood stoves, and materials for buildings, and the continuous forming processing is started from glass raw materials.

An embodiment of the continuous forming apparatus for crystallized glass according to the present invention will be described below with reference to the drawings. However, the present invention is not limited to this embodiment.

The continuous forming apparatus shown in fig. 1 includes: a melting apparatus 11, an adjusting apparatus 12, a devitrification prevention apparatus 13, a roll forming apparatus 14, a crystallization apparatus 17 (a roll tunnel kiln 17), and a cutting apparatus 27.

The melting apparatus 11 is an apparatus for melting a glass raw material into a molten glass, and may be a batch furnace having functions of melting, refining, homogenizing, etc. of a glass raw material, or a connection furnace of a type in which the above-described functions are connected as a unit.

The molten glass obtained in the melting apparatus 11 is conveyed to an adjusting apparatus 12 disposed downstream in the conveying direction. The adjusting device 12 is a device for adjusting the uniformity, viscosity and liquid level of the molten glass. The adjustment device 12 is provided with a liquid level control device 12a, a stirring device 12b (stirring rod 12 b), a heating element 12c, and a thermocouple 12 d.

The liquid level control means 12a detects the liquid level of the molten glass, and feeds back a signal corresponding to the amount of change in the liquid level to glass raw material charging means (not shown) for charging the glass raw material into the melting means 11, thereby correcting the amount of charged raw material. As mentioned above, the liquid level in the regulating device 12 is adjusted to a predetermined value.

The stirring device 12b stirs the molten glass to homogenize it. The heating element 12c and the thermocouple 12d adjust the temperature of the molten glass and the viscosity of the molten glass to a predetermined value.

The molten glass flowing out of the self-regulating apparatus 12 flows into the devitrification prevention apparatus 13 disposed downstream in the conveying direction. The devitrification prevention device 13 is provided with a heat insulating device 13a (heat insulating refractory 13 a), a lip brick 13b, and a bracket 13 c. The holding device 13a holds the molten glass at a predetermined temperature. The lip 13b guides the molten glass to the roll forming device 14. The bracket 13c is a supporter supporting the lip tile 13 b. Further, although not necessarily required, a heating element 13d may be provided in the devitrification prevention apparatus 13. The heating element 13d is a heating device disposed through the bracket 13c, and the bracket 13c and the lip 13b are heated by the heating element 13 d.

The devitrification prevention means 13 keeps the temperature of the molten glass at a predetermined level before the molten glass is introduced into the roll forming means 14 by keeping the temperature by the heat keeping means 13a, thereby preventing devitrification of the molten glass. When the heating element 13d is provided in the devitrification prevention device 13, the molten glass can be prevented from devitrification by heating with the heating element 13 d.

The molten glass flowing out of the self-regulating device 12 and passing through the devitrification prevention device 13 is supplied to a roll forming device 14 disposed downstream in the conveying direction. The roll forming device 14 roll-forms the molten glass into a belt-shaped sheet glass. The roll forming apparatus 14 is provided with an upper roller 14a, a lower roller 14b, and a cooling water tank 14 c. The rollers constituting the upper roller 14a and the lower roller 14b may be commercially available ones, and are made of a material excellent in heat resistance, thermal shock resistance, high-temperature strength, and thermal crack resistance.

The upper roll shaft 14a and the lower roll shaft 14b are arranged to face each other, and the molten glass supplied between the pair of roll shafts is formed into a belt shape by roll forming. The cooling water tank 14c continuously supplies water to the inside thereof for cooling the molten glass, cools the glass that is rolled and formed into a belt shape, and maintains the belt shape.

The glass rolled and formed into a ribbon shape by the roll forming device 14 is carried by a carrying device 15 disposed downstream in the carrying direction. The conveyance means 15 is composed of a plurality of rollers arranged in a row and conveys the rolled sheet glass. The conveyance means 15 may be constituted by a mechanism capable of conveying the belt-like plate glass, such as a heat-resistant belt, in addition to the roller shaft.

A pressing roller 16 for pressing the belt-shaped sheet glass roll-formed by the roll forming device 14 is provided on the upper side of the upstream side in the conveying direction of the conveying device 15. The press roll shaft 16 is made of steel having excellent heat resistance, and is composed of 1 to several roll shafts. After the roll forming device 14 roll-forms the glass into a belt shape, a flat belt-shaped sheet glass a is formed by pressing by the press roll shaft 16. The pressing roller 16 is not necessarily required and may be omitted depending on the surface properties of the belt-shaped sheet glass roll-formed by the roll forming device 14.

The belt-like plate glass A is conveyed by the conveying means 15 and introduced into the crystallizing means 17. The crystallization device 17 is composed of the following regions in order from the upstream in the conveying direction: a nucleation region 23 for forming nuclei by maintaining the band-shaped plate glass A at a nucleation temperature; a temperature raising region 24 for raising the ambient temperature from the crystal nucleus formation temperature to the crystal growth temperature; a crystal growth region 25 for maintaining the strip-shaped plate glass A at a crystal growth temperature to grow crystals into a strip-shaped crystallized glass plate B; and a slow cooling region 26 for gradually cooling the belt-shaped crystallized glass plate B. The nucleation region 23, the temperature-raising region 24, the crystal growth region 25, and the slow-cooling region 26 control the ambient temperature of each region so as to have a temperature gradient as shown in fig. 2A or fig. 2B. The temperature gradient shown in fig. 2A is: the temperature gradient of the slow cooling is set to be slow. The temperature gradient shown in fig. 2B is: the temperature gradient of the slow cooling is set to be in multiple stages of rapid cooling, heat preservation and rapid cooling.

The crystallization device 17 is a commercially available roll tunnel kiln provided with heating elements 18, carrying rolls 19, thermocouples 20, and a stirring device 28.

The heating elements 18 are arranged in the number of 1 or a plurality of heating elements 18 on the side wall of the furnace above and below the transport rolls 19 in the nucleation zone 23, the temperature raising zone 24, the crystal growth zone 25, and the slow cooling zone 26, and a thermocouple 20 is provided for each heating element 18 to enable temperature control with a precision of + -5 ℃. The stirring device 28 stirs the air in each zone and homogenizes the temperature of each zone. By using these apparatuses, the crystallization heat treatment can be surely performed, and the crystallization of the rolled and formed strip plate glass can be easily and surely performed. Further, the heating source may be selected from a SiC heating element, a silicon molybdenum rod heater, gas, electricity, and the like as appropriate according to the desired temperature.

The transport roller shaft 19 is composed of a heat-resistant roller shaft, and continuously transports the belt-shaped plate glass in the crystallization device 17 without stagnation.

The crystal nucleus formation region 23, in which crystal nuclei are formed in the belt-shaped plate glass a, is maintained at a predetermined temperature.

The temperature raising region 24 is a region in which the band-shaped plate glass a forming the crystal nuclei is raised to the crystal growth temperature. The temperature raising region 24 has a predetermined temperature gradient as shown in fig. 2A or 2B, and the temperature of the belt-shaped plate glass a is gradually raised as the belt-shaped plate glass a is conveyed toward the outlet of the crystallization apparatus 17.

The crystal growth region 25 is a region in which the band-shaped plate glass a is crystallized into the band-shaped crystallized glass plate B while being kept at a temperature at which crystal growth proceeds.

The slow cooling zone 26 is: in order to remove the permanent strain from the belt-shaped crystallized glass plate B and form a uniform glass, the region of the belt-shaped crystallized glass plate B is gradually cooled. The slow cooling zone 26 is provided with a predetermined temperature gradient as shown in fig. 2A or 2B, and the belt-shaped crystallized glass plate B is gradually cooled as it is conveyed toward the outlet of the crystallization apparatus 17.

The belt-shaped crystallized glass plate B obtained by crystallizing the belt-shaped plate glass A by the crystallizing device 17 is conveyed to the cutting device 27 disposed downstream in the conveying direction. The cutting device 27 cuts the belt-shaped crystallized glass plate B to a predetermined size. The crystallized glass plate C cut by the cutting means 27 is transported to a secondary processing factory and is subjected to secondary processing to obtain a finished product.

The present invention will be described more specifically with reference to the following examples, but the scope of the present invention is not limited to the examples shown below.

The impact strength of the crystallized glass plate obtained in the following examples and comparative examples was evaluated by calculating the breakage rate (%) in the following manner using an impact testing apparatus described in International Electrotechnical Commission (IEC) publication 817 "spring-driven impact testing apparatus and calibration thereof".

The surface of the crystallized glass plate which was impact-cut into a size of 30 cm. times.30 cm. times.4 mm was impact-cut 3 times at 5 positions using an impact tester of 0.5J. The crystallized glass plate was judged as passing with no crack or breakage, and as failing with crack or breakage, and the rate of failure (the number of failing pieces relative to the total number of pieces supplied to the test) was regarded as the breakage rate (%).

In the example, a continuous molding apparatus having the same structure as that shown in fig. 1 was prepared and carried out. In a comparative example, an apparatus having the same configuration as that of the continuous molding apparatus disclosed in Japanese patent application laid-open No. 2005-41726 is prepared and implemented. In the crystallization steps of examples and comparative examples, the temperature was the ambient temperature in each zone of the crystallization apparatus.

Example 1 is:

a glass raw material prepared into a composition of mass percent of SiO263.5%, Al2O321.5%, MgO 0.5%, ZnO1.5%, BaO 1.8%, TiO22.8%, ZrO21.5%, B2O30.3%, P2O51.0%, Na2O0.7%, K2O 0.5.5%, Li2O 3.6.6%, As2O30.5% and V2O50.3% is put into a melting device. The glass raw material was melted at 1670 ℃ and then was rolled and molded into 170cm × 250m × 4mm by a molding machine to obtain a ribbon-shaped plate glass.

The belt-shaped plate glass obtained as described above was transported from the molding machine to the crystallizing machine, a 730 ℃ crystal nucleus formation region was charged, and the belt-shaped plate glass was maintained at 730 ℃ for 20 minutes while being transported in the crystal nucleus formation region, to form crystal nuclei in the belt-shaped plate glass.

Subsequently, the band-shaped plate glass forming the crystal nuclei was heated to 880 ℃ at a rate of 5 ℃ per minute and passed through the heating zone.

Thereafter, the ribbon-shaped plate glass forming the crystal nuclei was introduced into a crystal growth zone at 880 ℃, and was held at 880 ℃ for 30 minutes while being conveyed in the crystal growth zone, and crystals were grown to form a ribbon-shaped crystallized glass plate.

Subsequently, the belt-shaped crystallized glass plate was gradually cooled to 100 ℃ at a rate of 5 ℃/min and passed through a slow cooling zone.

Then, the belt-shaped crystallized glass plate was cut into a plate having a length of 100cm along the conveying direction by a cutting device.

Therefore, a solid solution of β -quartz as the main crystal was precipitated, and a black crystallized glass plate was obtained. The crystallized glass plate is free from waviness, deformation, cracking, and cracks, and has a flat and beautiful appearance. The breakage rate of the crystallized glass plate is 5% or less.

Example 2 is:

glass raw materials prepared to the mass percentage of SiO264.0%, Al2O322.0%, MgO 0.5%, ZnO1.0%, BaO 2.0%, TiO22.5%, ZrO21.5%, B2O30.3%, P2O50.8%, Na2O0.8%, K2O 0.3.3%, Li2O 3.8.8% and As2O30.5% are put into a melting device. The glass raw material was melted at 1650 ℃ and then was rolled and molded into 170cm × 250m × 4mm by a molding machine to obtain a ribbon-shaped plate glass.

The belt-shaped plate glass obtained as described above was transported from the molding machine to the crystallizing machine, and a crystal nucleus formation region at 750 ℃ was introduced, and the belt-shaped plate glass was maintained at 750 ℃ for 20 minutes while being transported in the crystal nucleus formation region, to form crystal nuclei in the belt-shaped plate glass.

Subsequently, the band-shaped plate glass forming the crystal nuclei was passed through the temperature-raising region while raising the temperature to 1000 ℃ at a rate of 5 ℃/min.

Thereafter, the ribbon-shaped plate glass forming the crystal nuclei was introduced into a crystal growth zone at 1000 ℃ and held at 1000 ℃ for 30 minutes while being conveyed in the crystal growth zone, and crystals were grown to form a ribbon-shaped crystallized glass plate.

Next, the belt-shaped crystallized glass plate was gradually cooled to 100 ℃ at a rate of 5 ℃ per minute and passed through a slow cooling zone.

Therefore, β -spodumene was precipitated as a main crystal, and a white crystallized glass plate was obtained. The crystallized glass plate is free from waviness, deformation, cracking, and cracks, and has a flat and beautiful appearance. The breakage rate of the crystallized glass plate is 5% or less.

Comparative example 1 is as follows:

The belt-like plate glass obtained as described above was transported from the molding facility to the crystallization facility, charged into a temperature range of 600 ℃, and kept at 600 ℃ for 10 minutes while being transported in the temperature range, and kept at a temperature near the glass transition temperature.

Subsequently, the belt-shaped plate glass was heated to 730 ℃ at a rate of 10 ℃ per minute and passed through the first heating zone.

Thereafter, the belt-shaped plate glass was put into a crystal nucleus formation region of 730 ℃ and kept at 730 ℃ for 20 minutes while being transported in the crystal nucleus formation region, and crystal nuclei were formed in the belt-shaped plate glass.

Next, the band-shaped plate glass forming the crystal nuclei was heated to 880 ℃ at a rate of 5 ℃ per minute, and passed through a second temperature-raising zone.

Subsequently, the ribbon-shaped plate glass forming the crystal nuclei was introduced into a crystal growth zone at 880 ℃, and was held at 880 ℃ for 30 minutes while being conveyed in the crystal growth zone, and crystals were grown to form a ribbon-shaped crystallized glass plate.

Thereafter, the belt-shaped crystallized glass plate was gradually cooled to 100 ℃ at a rate of 5 ℃/min and passed through a slow cooling zone.

Claims

1. A method for continuously forming crystallized glass, comprising:

a melting step of melting a glass raw material to obtain molten glass;

a cutting step of cutting the belt-shaped crystallized glass plate;

and the crystallization step has:

a crystal nucleus formation step of directly putting the ribbon-shaped plate glass obtained in the forming step into an environment at a crystal nucleus formation temperature, maintaining the ribbon-shaped plate glass at the crystal nucleus formation temperature, and forming crystal nuclei in the ribbon-shaped plate glass;

a temperature rising step, namely, heating the strip plate glass forming the crystal nucleus to a crystal growth temperature at a temperature rising speed of 0.5-10 ℃/min;

and a slow cooling step of gradually cooling the ribbon-shaped crystallized glass plate at a cooling rate of 0.5 ℃/min to 20 ℃/min, wherein the temperature gradient of the slow cooling is set to be a plurality of stages of rapid cooling, heat preservation and rapid cooling.

2. The continuous forming method according to claim 1, wherein between the melting step and the forming step, the continuous forming method further comprises:

3. A continuous forming apparatus for crystallized glass, characterized by comprising:

a melting device that melts a glass raw material to obtain molten glass;

a cutting device for cutting the belt-shaped crystallized glass plate;

and the crystallization apparatus has:

a crystal nucleus forming region for directly containing the strip plate glass obtained by the forming device in an environment of crystal nucleus forming temperature and keeping the temperature at the crystal nucleus forming temperature to form crystal nuclei in the strip plate glass;

in the temperature rising area, the temperature of the strip plate glass forming the crystal nucleus is raised to the crystal growth temperature at the temperature rising speed of 0.5-10 ℃/min;

and a slow cooling region for gradually cooling the belt-shaped crystallized glass plate at a cooling rate of 0.5-20 ℃/min, wherein the temperature gradient of the slow cooling is set to be a plurality of stages of rapid cooling, heat preservation and rapid cooling.

4. The continuous forming apparatus of claim 3, wherein between the melting apparatus and the forming apparatus, the continuous forming apparatus further comprises: