A glass melting apparatus and method of use

Abstract

The invention is a glass melting equipment and its using method. It belongs to the technical field of optical glass melting production equipment. It mainly solves the problem of the increase of Pt loss and the serious decline of the transmittance of the glass caused by the Pt melting into the color due to the high content of alkali metal in the current melting glass. Its main features are: including a crucible, a material leakage pipe, a cooling device and a heating device; the cooling device includes a cooling device acting end surrounding the crucible; the crucible and the cooling device acting end are made of non-conductor material; the heating device is an electromagnetic induction device, including an electromagnetic induction device acting end surrounding the outer periphery of the cooling device acting end. The invention has the characteristics of completely avoiding the introduction of Pt and other impurity particles, and realizing the lowest impurity introduction amount and the best transmittance. It is mainly used for the melting of optical glass grades with the total content of K2O, Na2O and Li2O being 9%-19%.

Description

Technical Field

[0001] This invention belongs to the technical field of optical glass melting production equipment, specifically relating to a glass melting equipment and its usage method. Background Technology

[0002] In recent years, with the continuous improvement of living standards, people have higher demands for the imaging quality of cameras, projectors, VR devices, and other optical imaging equipment. Besides being related to optical design, photosensitive components, and coatings, the most important influencing factor on the imaging quality of optical equipment is the transmittance performance of the optical lenses.

[0003] In the pursuit of lightweighting and miniaturization, the optics industry is increasingly seeking higher refractive indices for optical lenses. Achieving high refractive indices in optical glass inevitably involves introducing macromolecular elements such as La, Ti, and Nb into the glass composition. However, these macromolecular elements often negatively impact high transmittance. Furthermore, current optical glass production primarily utilizes Pt crucibles for melting. With the introduction of more macromolecular elements, the melting temperature of the glass increases accordingly. The melting temperature of ordinary lanthanide glasses is generally above 1300℃, with some grades even reaching 1500℃. Higher melting temperatures lead to a greater amount of Pt melting into the glass, resulting in increased Pt loss and higher optical glass costs. Additionally, the transmittance of the glass decreases significantly due to the coloration caused by the infiltrated Pt. Summary of the Invention

[0004] The present invention addresses the above-mentioned shortcomings by providing a glass melting equipment and a method of use.

[0005] To address the issue of platinum crucible walls being eroded by high temperatures during the melting stage, leading to platinum particles melting into the glass and affecting the transmittance of optical glass products, this invention defines the production process for optical glass as follows: A glass melting crucible is manufactured using a non-conductive material. Before the formal melting process begins, a layer of the specified glass grade is deposited on the inner wall of the crucible and kept solidified by water cooling. At the start of the formal melting process, the raw materials to be melted are prepared according to the glass formula. A small amount of molten glass is first injected into the crucible for initial heating and melting. Electromagnetic induction heating is used to generate eddy currents within the molten glass. Once the molten glass reaches the preset melting temperature, the raw materials are added. After melting, the molten glass is poured into a mold through a controlled discharge pipe at the bottom of the crucible, thus completing the glass melting and production process.

[0006] The technical solution for the melting equipment of the present invention is: a glass melting equipment, including a crucible, a discharge pipe and a heating device, characterized in that: it further includes a cooling device; the cooling device includes a cooling device working end surrounding the crucible; both the crucible and the cooling device working end are made of non-conductive material; the heating device is an electromagnetic induction device, including an electromagnetic induction device working end surrounding the cooling device working end.

[0007] In the technical solution of the smelting equipment of the present invention, the working end of the cooling device is a tubular cooling device with a spiral distribution; the upper and lower ends of the tubular cooling device are the upper port and the lower port of the tubular cooling device, respectively.

[0008] In the technical solution of the smelting equipment of the present invention, the cooling device working end (3) is attached to the outer wall of the crucible and fixed to the crucible by the encapsulation layer; the electromagnetic induction device working end is surrounded by the encapsulation layer.

[0009] The electromagnetic induction device in the technical solution of the smelting equipment of the present invention has a tubular electromagnetic induction device with a spiral distribution at the working end.

[0010] In the technical solution of the smelting equipment of the present invention, the upper and lower ends of the tubular electromagnetic induction device are respectively the upper port and the lower port of the electromagnetic induction device.

[0011] The crucible in the technical solution of the smelting equipment of the present invention is made of quartz or mullite corundum; the working end of the cooling device is made of quartz.

[0012] The technical solution of the present invention is: a method for using a glass melting device, characterized by comprising the following steps:

[0013] (1) Before the formal melting and production begins, a layer of glass of the same grade as the glass to be melted with a high alkali metal content is attached to the inner wall of the crucible; after the solidified layer is stable, the unsolidified glass liquid is discharged through the high leakage pipe, thereby completing the solidification of the attached layer.

[0014] (2) When the melting officially begins, prepare the raw materials to be melted according to the glass formula of the glass grade with high alkali metal content to be melted;

[0015] (3) First, a small amount of molten glass is poured into the crucible for heating and melting. The molten glass is heated by electromagnetic induction to generate eddy currents inside. When the temperature of the molten glass reaches the preset melting temperature, the raw materials are added and the melting is carried out.

[0016] (4) After melting is completed, the glass melt is poured into the mold by controlling the bottom of the crucible discharge pipe to form the glass melting production.

[0017] The technical solution of the method of this invention includes the following steps:

[0018] (1) Before the formal melting and production begins, a layer of glass of the same grade as the glass to be melted with a high alkali metal content is attached to the inner wall of the crucible. By matching and controlling the electromagnetic induction power and the cooling process of the outer wall of the crucible, the thickness of the solidified layer of the same grade of glass attached to the inner wall of the crucible is always kept above 10mm. After the solidified layer is stable, the control current of the leakage tube is increased so that the uncured glass liquid flows out from the leakage tube, thereby completing the solidification of the attached layer.

[0019] (2) When the melting officially begins, prepare the raw materials to be melted according to the glass formula of the glass grade with high alkali metal content to be melted;

[0020] (3) First, a small amount of molten glass is injected into the crucible for heating and ignition. The molten glass is heated by electromagnetic induction to generate eddy currents inside. When the temperature of the molten glass reaches the preset melting temperature, the raw materials to be melted are gradually added into the crucible. The output power of the electromagnetic induction generator and the flow rate of the coolant in the cooling device are adjusted appropriately to match and stabilize them before melting.

[0021] (4) After melting is completed, the glass melt is poured into the mold by controlling the bottom of the crucible discharge pipe to form the glass melting production.

[0022] Step (1) in the technical solution of the method of the present invention is as follows:

[0023] (1) Before the formal smelting begins, pour the same grade of glass melt with high alkali metal content that has been melted by other equipment into the crucible, and turn on the electromagnetic induction device. When the glass melt generates eddies and gradually heats up to above the melting temperature, gradually add glass slag or glass melt of the same grade into the crucible. When the crucible is full of glass melt, turn on the cooling device, and appropriately adjust the output power of the electromagnetic induction generator and the flow rate of the coolant in the cooling device to match and stabilize them, and cool and solidify the glass melt close to the crucible wall to form a solidified layer of more than 10 mm. When the solidified layer is stable, increase the control current of the drain pipe to make the unsolidified glass melt flow out from the drain pipe, thereby completing the solidification of the adhesion layer.

[0024] The glass grade with high alkali metal content to be melted in the technical solution of the method of the present invention is an optical glass grade with one or more of K2O, Na2O and Li2O in total content of 9% to 19%.

[0025] The crucible is made of a non-conductive material to avoid overheating during electromagnetic induction, ensuring that a sufficient layer of the original glass grade adheres to the inner wall of the crucible and remains solidified under the cooling effect of the outer wall cooling device. Since the eddy current intensity generated by electromagnetic induction heating inevitably fluctuates, to prevent the solidified layer inside the crucible from melting and contacting the inner wall material, the electromagnetic induction power and the outer wall cooling process need to be matched and controlled to maintain the thickness of the original glass grade layer adhering to the inner wall of the crucible at least 10 mm.

[0026] To ensure effective cooling, the active end of the cooling device must be tightly attached to the outer wall of the crucible. The cross-section of the active end can be circular, elliptical, or rectangular. Since the active end of the cooling device is surrounded by the active end of the electromagnetic induction device, both the cooling device and the internal coolant must be non-conductive. The active end of the cooling device is made of quartz, and the internal coolant can be kerosene or pure water. To ensure the lifespan of the equipment and reduce the risk of damage to the adapting materials due to expansion, vibration, gravity, etc., the active end of the cooling device can be sealed and fixed with heat-resistant resin or cement after installation.

[0027] At room temperature, glass is a poor conductor, but as the temperature rises, its resistivity gradually decreases, and it becomes a good conductor when it melts into a liquid state. Therefore, before the formal melting begins, a small amount of molten glass needs to be poured into the crucible to heat and initiate the melting process. Once the temperature of the molten glass reaches the preset melting temperature, the raw materials are then added. The raw materials can be added in small, continuous amounts or in measured increments.

[0028] The heating method of this invention is electromagnetic induction heating. Its principle is to utilize the characteristic that molten glass is a good conductor to generate eddy currents and heat inside the molten glass. However, in order to make the melting performance of the glass good enough and the eddy current heating efficiency generated in the glass high enough, this solution is suitable for glass grades with high alkali metal content, specifically glass grades with ∑(K2O+Na2O+Li2O) content between 9% and 19%. If the ∑(K2O+Na2O+Li2O) content is less than 9%, the eddy current generated in the molten glass is not high enough, making it difficult to melt. If the ∑(K2O+Na2O+Li2O) content is higher than 19%, the solidified layer of this grade of glass adhering to the inner wall of the crucible is easily melted, causing the molten glass to come into contact with the inside of the glass and cause contamination.

[0029] The purpose of using this grade of glass to form a solidified layer on the inner wall of the crucible is twofold: firstly, to prevent the molten glass from contacting the crucible wall and affecting the transmittance of the optical glass; and secondly, to avoid internal streaks caused by inconsistent internal composition of the glass.

[0030] The beneficial effects of this invention are: during the entire melting process, the glass raw material does not come into contact with platinum or bricks containing impurity elements, but only with the glass curing layer formed by this grade, completely avoiding the introduction of impurity particles such as Pt, thereby achieving the invention goal of minimizing the amount of impurities introduced and achieving the best transmittance, and maximizing the transmittance performance of the glass product. Attached Figure Description

[0031] Figure 1 This is a perspective view of the glass melting equipment in Embodiment A of the present invention.

[0032] Figure 2 This is a cross-sectional view of the glass melting equipment in Embodiment A of the present invention.

[0033] Figure 3 This is a perspective view of the glass melting equipment in Embodiment B of the present invention.

[0034] Figure 4 This is a cross-sectional view of the glass melting equipment in Embodiment B of the present invention.

[0035] In the figure: 1-Crucible, 2-Encapsulation layer, 3-Cooling device working end, 3-1-Upper port of tubular cooling device working end, 3-2-Lower port of tubular cooling device working end, 4-Electromagnetic induction device working end, 4-1-Upper port of electromagnetic induction device working end, 4-2-Lower port of electromagnetic induction device working end, 5-Discharge pipe. Detailed Implementation

[0036] The embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0037] Embodiment A of the glass melting equipment of the present invention is as follows: Figure 1 , Figure 2 As shown, it includes a crucible 1, a discharge pipe 5, a cooling device, and a heating device.

[0038] The crucible 1 is made of quartz and has the same structure, shape, and size as existing crucibles. The discharge pipe 5 is the same as existing discharge pipes and is equipped with a heating device located at the bottom of the crucible 1.

[0039] The cooling device includes a cooling device working end 3 surrounding the crucible 1. The cooling device working end 3 is a spirally distributed tubular cooling device working end, with its upper and lower ends being the upper port 3-1 and lower port 3-2, respectively. The upper port 3-1 and lower port 3-2 of the tubular cooling device working end are connected to other parts of the cooling device (not shown in the figure). The other parts of the cooling device are the same as those in existing cooling devices. The cooling device working end 3 is a circular tube made of quartz material. The internal circulating coolant is kerosene. The cooling device working end 3 is attached to the outer wall of the crucible body 1 and fixed to the crucible 1 by an encapsulation layer 2, forming a cylindrical whole. The encapsulation layer 2 is made of silicone resin or cement material.

[0040] The heating device is an electromagnetic induction device, including an electromagnetic induction device working end 4 surrounding the encapsulation layer 2. The electromagnetic induction device working end 4 is a tubular electromagnetic induction device working end with a spiral distribution. The upper and lower ends of the tubular electromagnetic induction device working end are the upper port 4-1 and the lower port 4-2 of the electromagnetic induction device working end, respectively, for connecting with other parts of the electromagnetic induction device (not shown in the figure).

[0041] Embodiment B of the glass melting equipment of the present invention is as follows: Figure 3 , Figure 4 As shown. Unlike Example A, the crucible 1 is made of mullite corundum, the cooling device's active end 3 is a square tube made of quartz, and the internal circulating coolant is pure water.

[0042] The present invention discloses a method for using a glass melting apparatus, comprising the following steps:

[0043] (1) Before the formal smelting begins, pour the same grade of glass melt with high alkali metal content that has been melted by other equipment into the crucible, and turn on the electromagnetic induction device. When the glass melt generates eddies and gradually heats up to above the melting temperature, gradually add glass slag or glass melt of the same grade into the crucible. When the crucible is full of glass melt, turn on the cooling device, and appropriately adjust the output power of the electromagnetic induction generator and the flow rate of the coolant in the cooling device to match and stabilize them, and cool and solidify the glass melt close to the crucible wall to form a solidified layer of more than 10 mm. When the solidified layer is stable, increase the control current of the drain pipe to make the unsolidified glass melt flow out from the drain pipe, thereby completing the solidification of the adhesion layer.

[0044] (2) When the melting officially begins, prepare the raw materials to be melted according to the glass formula of the glass grade with high alkali metal content to be melted;

[0045] (3) First, a small amount of molten glass is injected into the crucible for heating and ignition. The molten glass is heated by electromagnetic induction to generate eddy currents inside. When the temperature of the molten glass reaches the preset melting temperature, the raw materials to be melted are gradually added into the crucible. The output power of the electromagnetic induction generator and the flow rate of the coolant in the cooling device are adjusted appropriately to match and stabilize them before melting.

[0046] (4) After melting is completed, the glass melt is poured into the mold by controlling the bottom of the crucible discharge pipe to form the glass melting production.

[0047] A glass melting crucible 1 is manufactured using a non-conductive material. A cooling device is installed, with its active end 3 mounted on the outer side of the crucible 1 wall. The active end 3 is then encapsulated and fixed using encapsulation material 2, forming an encapsulation layer 2. An electromagnetic induction generator is installed, with its active end surrounding the crucible 1 and the active end 3 of the cooling device. Molten glass of this grade, melted using other equipment, is poured into the crucible 1. The electromagnetic induction generator is then activated, generating eddies within the molten glass and gradually raising the temperature above the melting point. Simultaneously, slag or molten glass of this grade is gradually added to the crucible 1. Once the crucible is full, the cooling device is activated, allowing the coolant to flow within the active end 3 of the cooling device to achieve a cooling effect. The output power of the electromagnetic induction generator and the flow rate of the coolant in the cooling device are appropriately adjusted to ensure matching and stability, allowing the molten glass close to the crucible wall to cool and solidify, forming a solidified layer of at least 10 mm. Once the cured layer is stable, the control current of the feed tube 5 is increased, causing the uncured molten glass to flow out of the feed tube 5, thereby completing the curing of the adhesion layer of the grade to be melted.

[0048] In formal production, the raw materials to be melted are prepared according to the glass formula. The melting process is the same as above. First, a small amount of molten glass is poured into crucible 1 for heating and initiation. Electromagnetic induction heating is used to generate eddy currents inside the molten glass. When the temperature of the molten glass reaches the preset melting temperature, the raw materials are formally added. After melting, the molten glass is poured into the mold through the discharge pipe 5 at the bottom of the crucible to form the glass, thus realizing glass melting and production. Throughout the melting process, the glass raw materials do not come into contact with platinum or bricks containing impurity elements, but only with the glass hardening layer formed by this grade, thereby achieving the invention goal of minimizing impurity introduction and optimizing transmittance.

[0049] Example A of the method of using glass melting equipment according to the present invention:

[0050] A 5L crucible was constructed using quartz. The smelting grade was H-ZF1S, with a ∑R2O content of 18.6%, a Na2O content of 12.2%, and a K2O content of 6.4%. The cooling device consisted of a circular quartz tube at the working end, with kerosene circulating as the coolant at a pressure of 0.4MPa and a flow rate of 30L / min. High-frequency electromagnetic induction heating was employed, with a three-phase input voltage of 380V, an operating frequency of 200kHz, and an input power of 18kW. When H-ZF1S was smelted using a pure platinum crucible, the internal transmittance at 400nm was 55.3%. After smelting using the method described in this invention, the internal transmittance at 400nm increased to 86.1%.

[0051] Example B of the method of using glass melting equipment of the present invention:

[0052] A 16L crucible was constructed using mullite-corundum. The smelting grade was H-F1S, with a ∑R2O content of 11.8%, including 6.5% Na2O, 4% K2O, and 1.3% Li2O. The cooling device consisted of a quartz square tube at the working end, with purified water circulating internally at a pressure of 0.5MPa and a flow rate of 50L / min. High-frequency electromagnetic induction heating was employed, with a three-phase input voltage of 380V, an operating frequency of 120kHz, and an input power of 40kW. When H-F1S was smelted using a pure platinum crucible, the product's internal transmittance at 400nm was 92.5%. After smelting using the method described in this invention, the product's internal transmittance at 400nm increased to 98.7%.

Claims

1. A glass melting apparatus for melting optical glass with high alkali metal content, comprising a crucible (1), a feed pipe (5), and a heating device, wherein the feed pipe (5) is disposed at the bottom of the crucible (1), characterized in that: It also includes a cooling device and an encapsulation layer (2); the cooling device includes a cooling device working end (3) surrounding the crucible (1), the cooling device working end (3) is attached to the outer wall of the crucible and fixed to the crucible (1) by the encapsulation layer (2) to form a cylindrical whole; the crucible (1) is made of quartz or mullite corundum, the cooling device working end (3) is made of quartz, and the encapsulation layer (2) is encapsulated with organosilicon resin or cement material; the heating device is an electromagnetic induction device, including an electromagnetic induction device working end (4) surrounding the cooling device working end (3), used to generate eddy current heating between the molten glass of the same grade with high alkali metal content to be melted and the glass melt, and to melt the added raw materials; the electromagnetic induction device working end (4) is a tubular electromagnetic induction device working end with a spiral distribution.

2. The glass melting equipment according to claim 1, characterized in that: The upper and lower ends of the cooling device are respectively the upper port (3-1) and the lower port (3-2) of the tubular cooling device.

3. The glass melting equipment according to claim 2, characterized in that: The electromagnetic induction device's active end (4) surrounds the outer periphery of the encapsulation layer (2).

4. A glass melting apparatus according to claim 1, 2 or 3, characterized in that: The upper and lower ends of the electromagnetic induction device are respectively the upper port (4-1) and the lower port (4-2) of the electromagnetic induction device.

5. A method using a glass melting apparatus according to any one of claims 1-4, characterized in that... Includes the following steps: (1) Before the formal melting and production begins, a layer of glass of the same grade as the glass to be melted with a high alkali metal content is attached to the inner wall of the crucible; after the solidified layer is stable, the unsolidified glass liquid is discharged through the leakage pipe, thereby completing the solidification of the attached layer. (2) When the melting officially begins, prepare the raw materials to be melted according to the glass formula of the glass grade with high alkali metal content to be melted; (3) First, a small amount of molten glass is poured into the crucible for heating and melting. The molten glass is heated by electromagnetic induction to generate eddy currents inside. When the temperature of the molten glass reaches the preset melting temperature, the raw materials are added and the melting is carried out. (4) After melting is completed, the glass melt is poured into the mold by controlling the bottom of the crucible discharge pipe to form the glass melting production.

6. A method using glass melting equipment according to claim 5, characterized in that... Includes the following steps: (1) Before the formal melting and production begins, a layer of glass of the same grade as the glass to be melted with a high alkali metal content is attached to the inner wall of the crucible. By matching and controlling the electromagnetic induction power and the cooling process of the outer wall of the crucible, the thickness of the solidified layer of the same grade of glass attached to the inner wall of the crucible is always kept above 10mm. After the solidified layer is stable, the control current of the leakage tube is increased so that the uncured glass liquid flows out from the leakage tube, thereby completing the solidification of the attached layer. (2) When the melting officially begins, prepare the raw materials to be melted according to the glass formula of the glass grade with high alkali metal content to be melted; (3) First, a small amount of molten glass is injected into the crucible for heating and ignition. The molten glass is heated by electromagnetic induction to generate eddy currents inside. When the temperature of the molten glass reaches the preset melting temperature, the raw materials to be melted are gradually added into the crucible. The output power of the electromagnetic induction generator and the flow rate of the coolant in the cooling device are adjusted appropriately to match and stabilize them before melting. (4) After melting is completed, the glass melt is poured into the mold by controlling the bottom of the crucible discharge pipe to form the glass melting production.

7. A method using glass melting equipment according to claim 6, characterized in that... The first step is as follows: (1) Before the formal smelting production begins, pour the same grade of glass melt with high alkali metal content that has been melted by other equipment into the crucible, and turn on the electromagnetic induction device. When the glass melt generates eddies and gradually heats up to above the melting temperature, gradually add glass slag or glass melt of the same grade into the crucible. When the crucible is full of glass melt, turn on the cooling device, and appropriately adjust the output power of the electromagnetic induction generator and the flow rate of the coolant in the cooling device to match and stabilize them, and cool and solidify the glass melt close to the crucible wall to form a solidified layer of more than 10 mm. When the solidified layer is stable, increase the control current of the leakage pipe to make the unsolidified glass melt flow out from the leakage pipe, thereby completing the solidification of the adhesion layer.

8. A method using glass melting equipment according to claim 5, 6, or 7, characterized in that: The glass grade to be melted with high alkali metal content is an optical glass grade containing one or more of K2O, Na2O and Li2O with a total content of 9% to 19%.

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