Quartz glass annealing furnace

Abstract

The application belongs to the field of quartz glass heat treatment and relates to a quartz glass annealing furnace. The quartz glass annealing furnace comprises an outer furnace body, an inner furnace body, a side heating body and an upper heating body. The outer furnace body is shaped with an openable and closable vacuum cavity. The inner furnace body is arranged in the vacuum cavity and comprises a lower cavity and an upper heat preservation cylinder. The upper heat preservation cylinder and the lower cavity enclose an inner heat preservation cavity for accommodating a quartz glass element. The upper end of the upper heat preservation cylinder is closed and the lower end is open. The lower end of the upper heat preservation cylinder extends downward to gap fit with the top circumferential edge of the quartz glass element. The upper heat preservation cylinder extends upward and protrudes from the top of the lower cavity. The thermal resistance of the upper part of the inner furnace body gradually increases from inside to outside in the radial direction. The side heating body is arranged on the inner side wall of the lower cavity and is distributed along the circumference of the quartz glass element. The upper heating body is arranged inside the upper heat preservation cylinder and above the quartz glass element. The quartz glass annealing furnace can make the thermal stress distribution of the quartz glass element after annealing treatment uniform.

Description

Technical Field

[0001] This application belongs to the field of quartz glass heat treatment and relates to a quartz glass annealing furnace. Background Technology

[0002] When preparing synthetic quartz materials using a two-step method, the commonly used process is to first obtain powder rods and then perform dehydroxylation sintering. During the dehydroxylation process, the removal of hydroxyl groups follows a diffusion mechanism, which is related to the diffusion path and the initial concentration distribution of hydroxyl groups. Hydroxyl groups in the material's edge region can preferentially detach from the matrix, while hydroxyl groups in the central region need to diffuse from the center to the edge region before they can be gradually removed. Therefore, the hydroxyl concentration of the final product will show a distribution trend of gradually decreasing from the center to the edge. The magnitude of this concentration difference varies depending on the level of the master rod preparation process.

[0003] In related technologies, traditional annealing processes typically ignore the impact of uneven hydroxyl distribution on the annealing effect. To avoid internal temperature differences caused by size effects, the industry generally uses extremely low cooling rates (e.g., 0.25℃ / h) to anneal quartz materials to avoid generating new stress during annealing. However, for quartz glass components with hydroxyl concentration gradients, and for applications with high requirements for stress birefringence, even with extremely low cooling rates (or even just heat preservation), viscosity differences caused by fluctuations in hydroxyl concentration will still ultimately lead to uneven distribution of internal thermal stress in the quartz glass component, causing problems such as excessive stress birefringence or substandard optical uniformity. Summary of the Invention

[0004] In view of the deficiencies or improvement needs of the prior art, this application provides a quartz glass annealing furnace, which aims to improve the problem of uneven thermal stress easily generated in quartz glass components during the annealing process.

[0005] This application provides a quartz glass annealing furnace, comprising: The outer furnace body has an openable and closable vacuum chamber inside. An inner furnace body, disposed within the vacuum chamber, includes a lower cavity and an upper insulation cylinder. The upper insulation cylinder is fixedly disposed at the top center of the lower cavity, together with the lower cavity forming an openable and closable inner insulation cavity for accommodating quartz glass elements. The upper insulation cylinder is closed at the upper end and open at the lower end, with the lower end extending downwards to form a clearance fit with the top circumferential edge of the quartz glass elements. The upper end of the upper insulation cylinder extends upwards and protrudes from the top of the lower cavity. The thermal resistance of the upper part of the inner furnace body increases progressively from the inside to the outside along the radial direction of the inner furnace body. A side heating element is mounted on the inner wall of the lower cavity and distributed circumferentially along the quartz glass element; The upper heating element is mounted inside the upper insulation cylinder and located above the quartz glass element.

[0006] As a further preferred embodiment, the lower cavity includes: The central insulation cylinder is a hollow tubular structure. The heat-insulating base is sealed to the bottom opening of the middle heat-insulating cylinder, and a through mounting port is provided at the center of the lower end face of the heat-insulating base. The lower insulation cover is detachably and sealed to the lower mounting port; The upper insulation cover is connected to the top opening of the middle insulation cylinder. The upper insulation cover has a through upper mounting port at the center of its upper end face. The upper insulation cylinder is interference-fitted to the upper mounting port.

[0007] As a further preferred embodiment, the thermal resistance of the upper insulation cylinder, the upper insulation cover, and the middle insulation cylinder increases sequentially.

[0008] As a further preferred embodiment, the upper insulation cylinder is coaxial with the quartz glass element, and the lower end face of the upper insulation cylinder is close to the upper circumferential edge of the quartz glass element, with an axial gap of 5mm to 15mm between them.

[0009] As a further preferred embodiment, the outer furnace body includes: The bottom shell has a chamber with an opening at the top; The upper transition cover has its lower end sealed to the top opening of the bottom shell, and its upper end gradually tapers upward to form a tapered transition section with an upper mounting hole; the upper insulation cylinder passes through the upper mounting hole. The upper cover has its lower end sealed to the top of the upper transition cover, and its upper end extends upward to the top of the upper insulation cylinder. The upper end of the upper cover has a closed structure.

[0010] As a further preferred embodiment, the bottom shell includes an intermediate cavity and a lower furnace cover. The intermediate cavity is a hollow tubular structure. The top of the intermediate cavity is sealed to the upper transition cover, and the lower furnace cover is detachably connected to the bottom of the intermediate cavity.

[0011] As a further preferred embodiment, the bottom shell, the upper transition cover, and the upper cover are all provided with cooling structures.

[0012] As a further preferred embodiment, the inner wall of the outer furnace body is provided with a plurality of support brackets circumferentially, one end of each support bracket being connected to the inner wall of the outer furnace body, and the other end extending inward to support the bottom of the inner furnace body.

[0013] As a further preferred embodiment, the quartz glass annealing furnace also includes a material rack, through which the quartz glass elements are mounted in the inner insulation cavity.

[0014] As a further preferred embodiment, the quartz glass annealing furnace also includes a frame and a drive mechanism, with the outer furnace body mounted on the frame and the drive mechanism used to control the opening and closing of the vacuum chamber and the inner insulation chamber.

[0015] In summary, compared with the prior art, the technical solutions conceived in this application have the following main technical advantages: 1. This application designs the inner furnace body with a unique "convex" shaped structure. The upper insulation cylinder at the top can suppress thermal communication between the heated area at the top and the circumferential heated area of ​​the quartz glass element. Combined with the independent zoned temperature control of the side heating element and the upper heating element, a "hat-like" isolation insulation structure can be formed on the top of the quartz glass element, achieving differentiated temperature control between the top and the circumference. At the same time, the inner furnace body adopts a gradient design with the thermal resistance gradually increasing from the inside to the outside along the radial direction, which can form a gradient heat dissipation effect and build a stable temperature gradient in the radial direction of the quartz glass element, so that the center temperature of the quartz glass element is always lower than the edge temperature. With this design, the temperature gradient can be matched with the gradient of hydroxyl concentration gradually decreasing from the center to the edge in the two-step synthesis of quartz materials: during the dehydroxylation sintering process, hydroxyl groups in the edge region are preferentially removed, while hydroxyl groups in the center region need to diffuse to the surrounding area first and then be gradually removed, ultimately maintaining the distribution characteristic of hydroxyl concentration gradually decreasing from the center to the edge of the quartz glass element; with this scheme design by constructing an adaptive temperature gradient, a technical solution can be formed in which the viscosity change at each position tends to be consistent during the annealing process, which can effectively eliminate the problem of uneven thermal stress distribution caused by uneven hydroxyl concentration distribution, and ensure that the thermal stress distribution of the quartz glass element is uniform after annealing.

[0016] 2. This application adopts a support frame design, which suspends and supports the inner furnace body inside the vacuum chamber. This avoids direct contact between the inner furnace body and the bottom of the outer furnace body, reducing unnecessary heat conduction and heat dissipation. It also simplifies the installation and fixing structure of the inner furnace body, reduces the impact of deformation of the outer furnace body support structure on the stability of the insulation structure under high temperature environment, and facilitates the disassembly and maintenance of the inner furnace body, reducing the difficulty and cost of equipment maintenance. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall structure of a quartz glass annealing furnace provided in an embodiment of this application; Figure 2 This is a cross-sectional view of the quartz glass annealing furnace provided in an embodiment of this application; Figure 3 This is a cross-sectional structural schematic diagram of the inner furnace body provided in the embodiments of this application; Figure 4This is a cross-sectional view of the inner furnace body and the outer furnace body provided in the embodiments of this application; Figure 5 This is a schematic diagram of the quartz glass annealing furnace in the start-up state provided in the embodiments of this application.

[0018] In all the accompanying drawings, the same reference numerals are used to denote the same elements or structures, wherein: 1. Outer furnace body; 101. Upper transition cover; 102. Upper cover; 103. Intermediate cavity; 104. Lower furnace cover; 2. Inner furnace body; 201. Upper insulation cylinder; 202. Middle insulation cylinder; 203. Insulation base; 204. Lower insulation cover; 205. Upper insulation cover; 3. Side heating element; 4. Upper heating element; 5. Support frame; 6. Material rack; 7. Frame; 8. Drive mechanism; 10. Quartz glass element. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0020] The following is in conjunction with the appendix Figures 1-5 This application will be described in further detail.

[0021] This application discloses a quartz glass annealing furnace. (Refer to...) Figures 1-3 The quartz glass annealing furnace includes an outer furnace body 1, an inner furnace body 2, a side heating element 3, and an upper heating element 4. The outer furnace body 1 has an openable and closable vacuum chamber inside. The inner furnace body 2 is located inside the vacuum chamber and includes a lower cavity and an upper insulation cylinder 201. The upper insulation cylinder 201 is fixedly located at the top center of the lower cavity. The upper insulation cylinder 201 and the lower cavity together form an openable and closable inner insulation chamber for accommodating the quartz glass element 10. The upper insulation cylinder 201 is closed at the top and open at the bottom. The lower end of the upper insulation cylinder 201 extends downward to form a clearance fit with the top circumferential edge of the quartz glass element 10. The upper end of the upper insulation cylinder 201 extends upward and protrudes from the top of the lower cavity. The thermal resistance of the upper part of the inner furnace body 2 increases gradually from the inside to the outside along the radial direction of the inner furnace body 2. The side heating element 3 is mounted on the inner wall of the lower cavity and distributed along the circumference of the quartz glass element 10. The upper heating element 4 is mounted inside the upper insulation cylinder 201 and located above the quartz glass element 10.

[0022] In this design scheme, by designing the inner furnace body 2 with a unique "convex" shaped structure, the upper insulation cylinder 201 can suppress the connection between the top heated area and the circumferential heated area of ​​the quartz glass element 10. Combined with the independent zoned temperature control of the side heating element 3 and the upper heating element 4, the top of the quartz glass element 10 forms a "hat-like" insulated structure, enabling differentiated temperature control between the top and the circumference. Simultaneously, based on the gradient design of the inner furnace body 2's thermal resistance increasing radially from the inside out, a gradient heat dissipation effect is formed, which can widen the temperature gradient along the diameter of the quartz glass element 10, ensuring that the center temperature of the quartz glass element 10 is always lower than the edge temperature. This temperature gradient can match the gradient of gradually decreasing hydroxyl concentration from the center to the edge in the two-step synthesis of quartz materials. During the dehydroxylation sintering process, hydroxyl groups in the edge region are preferentially removed, while hydroxyl groups in the center region need to diffuse from the center region to the surrounding region before being gradually removed. Therefore, the hydroxyl concentration gradually decreases from the center to the edge. This scheme of establishing a temperature gradient so that the viscosity change at each position during annealing tends to be consistent can effectively eliminate the problem of uneven thermal stress caused by uneven hydroxyl concentration.

[0023] Furthermore, such as Figure 3 As shown, in some embodiments, the lower cavity includes a central insulation cylinder 202, an insulation base 203, a lower insulation cover 204, and an upper insulation cover 205. The central insulation cylinder 202 is a hollow tubular structure; the insulation base 203 is sealed to the bottom opening of the central insulation cylinder 202, and a through lower mounting port is provided at the center of the lower end face of the insulation base 203; the lower insulation cover 204 is detachably and sealed to the lower mounting port; the upper insulation cover 205 is closed and connected to the top opening of the central insulation cylinder 202, and a through upper mounting port is provided at the center of the upper end face of the upper insulation cover 205, with the upper insulation cylinder 201 interference-fitted to the upper mounting port.

[0024] Preferably, the upper insulation cylinder 201 is coaxial with the quartz glass element 10, and the lower end face of the upper insulation cylinder 201 is close to the upper circumferential edge of the quartz glass element 10, with an axial gap of 5mm to 15mm between them. For example, the axial gap can be 5mm, 10mm, 12mm, 15mm, etc.; preferably 10mm.

[0025] In this design, if the gap is too small, the upper insulation cylinder 201 may come into contact with the quartz glass element 10 under high temperature conditions, causing damage to the element. If the gap is too large, it will not provide good regional thermal insulation and will not effectively separate the circumferential heating area from the top heating area. A gap range of 5mm to 15mm ensures both structural safety and meets the thermal insulation requirements.

[0026] Furthermore, in some embodiments, the thermal resistance of the upper insulation cylinder 201, the upper insulation cover 205, and the middle insulation cylinder 202 increases sequentially. The core purpose of this design is to make the heat dissipation rate of the inner furnace body 2 decrease radially from the inside to the outside (i.e., from the center to the outer periphery), so as to form a controllable temperature gradient with a low center temperature and a high edge temperature, which matches the hydroxyl concentration distribution law of the quartz glass element 10 itself and ensures the stress relief effect after annealing.

[0027] It is understandable that the gradual increase in thermal resistance can be achieved by adjusting the material density, material thickness, or selecting insulation materials with different thermal conductivity, among other methods. In some preferred embodiments, the upper insulation cylinder 201, the upper insulation cover 205, and the middle insulation cylinder 202 can be made of insulation materials with the same or essentially the same thermal conductivity, and the difference in thermal resistance can be achieved by adjusting the thickness of each component. Adjusting the thickness of each component mainly refers to setting a structural morphology in which the thickness of the upper insulation cylinder 201, the upper insulation cover 205, and the middle insulation cylinder 202 gradually increases, thereby achieving a gradual increase in the thermal resistance of the upper insulation cylinder 201, the upper insulation cover 205, and the middle insulation cylinder 202.

[0028] As a preferred embodiment, in some cases, a structural scheme with basically the same thermal conductivity and progressively increasing thickness is used as an example. The central insulation cylinder 202 includes a skeleton and a covering layer. The skeleton is preferably a carbon-carbon composite material, formed by splicing multiple carbon-carbon composite plates and connectors. The covering layer is preferably graphite soft felt, which is tightly wrapped around the skeleton. The insulation base 203 is an annular structure made of isostatically pressed graphite, with a through-hole at the center of its lower end face. The lower insulation cover 204, the upper insulation cover 205, and the upper insulation cylinder 201 are made of rigid insulation felt.

[0029] The upper insulation cylinder 201 has a thickness of 35mm~45mm, preferably 40mm; the upper insulation cover 205 has a thickness of 55mm~65mm, preferably 60mm; and the middle insulation cylinder 202 has a thickness of 75mm~85mm, preferably 80mm. The thicknesses of the insulation components gradually increase, creating a stepped distribution of radial thermal resistance. Simultaneously, the side heating element 3 and the upper heating element 4 are separated by the upper insulation cylinder 201, forming zoned control. This creates a thermal field with a certain temperature gradient in the radial direction around the quartz glass element 10 to be processed. Specifically, a temperature-controlled insulation and cooling stage can be set from 1300℃ to 1000℃, with the center temperature of the quartz glass element 10 being 10℃ lower than the edge area. Furthermore, under the above structural design, based on the thickness selection, in addition to creating a temperature gradient, it also ensures that when the set temperature is 1300℃, the external temperature of the inner furnace body 2 is below 300℃, resulting in good thermal insulation, low heat dissipation, and low energy consumption.

[0030] It is understandable that the heat dissipation of the quartz glass element 10 is mainly concentrated in the upper and circumferential areas of the quartz glass element 10. Since the heat is mainly dissipated upwards, and the quartz glass element 10 has side heating elements 3 arranged circumferentially and upper heating elements 4 arranged above, the thermal resistance distribution in the upper part of the inner furnace body 2 has the most significant impact on the temperature uniformity of the quartz glass element 10. Therefore, no special requirements are needed for the thermal resistance distribution at the bottom of the inner furnace body 2. It is understandable that the upper part of the inner furnace body 2 includes an upper insulation cylinder 201, an upper insulation cover 205, and a middle insulation cylinder 202. The bottom of the inner furnace body 2 includes a lower insulation cover 204 and an insulation base 203. The thermal resistance of the lower insulation cover 204 and the insulation base 203 can be set to be the same as or substantially the same as that of the middle insulation cylinder 202 to achieve the function of heat insulation.

[0031] Furthermore, in some embodiments, the quartz glass annealing furnace also includes a material rack 6, preferably a graphite material rack, through which the quartz glass element 10 is supported in the inner insulation cavity. By setting the material rack 6, it is possible to ensure that the quartz glass element 10 remains horizontal and stable during the annealing process, avoiding deformation caused by gravity or thermal stress. The structural design of the material rack 6 needs to take into account both support strength and thermal uniformity, and preferably adopts a hollow mesh structure to reduce obstruction of the thermal distribution and promote temperature uniformity within the furnace. It is understood that the material rack 6 can be fixed to the lower insulation cover 204 of the inner furnace body 2 by support columns, or the support columns can pass through the lower insulation cover 204 and be fixed to the lower furnace cover 104 of the outer furnace body 1, with a sealed insulation structure at the penetration point to prevent heat loss along the support columns.

[0032] Furthermore, such as Figure 3 As shown, in some embodiments, in order to achieve stable installation of the inner furnace body 2 in the vacuum cavity, a plurality of support brackets 5 are provided circumferentially on the inner wall of the outer furnace body 1. One end of the support bracket 5 is connected to the inner wall of the outer furnace body 1, and the other end extends inward to support the bottom of the inner furnace body 2.

[0033] Preferably, the support brackets 5 are evenly distributed along the inner circumference of the outer furnace body 1. The number of support brackets can be adjusted according to the size and weight of the outer furnace body 1 and the inner furnace body 2. For example, the support brackets 5 can be set to 6, 12 or other quantities to ensure that the inner furnace body 2 is subjected to uniform force and has a stable structure.

[0034] In some preferred embodiments, the support frame 5 is L-shaped, with one end fixed to the inner wall of the bottom shell and the other end extending horizontally inward to form a horizontal extension end; while the inner furnace body 2 is entirely situated on the horizontal extension ends of the numerous coplanar support frames 5 through the heat-insulating base 203, and the connection between the heat-insulating base 203 and the support frame 5 is achieved by screws or other fasteners, thereby forming a stable multi-point support structure.

[0035] Understandably, the support bracket 5 does not extend directly below the lower insulation cover 204 to avoid interfering with the space below the lower insulation cover 204, thereby providing sufficient space for the loading and unloading of the lower insulation cover 204 and the quartz glass element 10.

[0036] Compared to traditional designs, conventional annealing furnaces use a frame installed on the inner wall of the vacuum chamber of the outer furnace body 1 to support the inner furnace body 2. This frame is typically made of stainless steel, and its surface usually needs to be covered with graphite adhesive or soft felt, making installation inconvenient and difficult to maintain. In particular, stainless steel frames are heavy and prone to deformation under heat, easily leading to deformation of the inner furnace body 2. This application uses a support frame 5 design, which is easier to install, distributes stress more evenly, effectively reduces the risk of structural deformation, ensures the long-term installation stability of the inner furnace body 2, and prevents structural deformation from affecting the uniformity of the heat field distribution within the furnace.

[0037] Furthermore, such as Figure 4 As shown, in some embodiments, the outer furnace body 1 includes a bottom shell, an upper transition cover 101, and an upper cover 102, which are sequentially and sealed together to form a complete outer furnace body 1 structure. The bottom shell, as the main structure of the outer furnace body 1, has a chamber with a top opening. The lower end of the upper transition cover 101 is sealed to the top opening of the bottom shell, and the upper end of the upper transition cover 101 tapers upwards to form a tapered transition section with an upper mounting hole, through which the upper insulation cylinder 201 passes. The lower end of the upper cover 102 is sealed to the top of the upper transition cover 101, and its upper end extends upwards above the upper insulation cylinder 201; the upper end of the upper cover 102 has a closed structure.

[0038] Under this design, compared with the traditional one-piece top cover structure, by setting a conical transition section and an upwardly protruding top cover 102 structure, not only can the outer furnace body 1 have excellent structural strength, but the conical transition section of the top transition cover 101 can also effectively reduce the disorderly heat loss in the top area of ​​the outer furnace body 1. At the same time, since the above design can make the distance between the outer peripheral surface of the inner furnace body 2 and the inner peripheral wall of the outer furnace body 1 appropriate, it can better provide a balanced vacuum insulation environment for the inner furnace body 2.

[0039] Furthermore, the quartz glass annealing furnace of this application preferably adopts a bottom-feeding operation method. That is, bottom feeding is achieved by designing the bottom shell as a split structure and using an adjustable lower insulation cover 204 at the bottom of the inner furnace body 2. It is understood that in some other embodiments, a top-feeding method is not excluded; when using the top-feeding method, the quartz glass components can be placed and removed by opening and closing the upper cover 102 or the upper transition cover 101, and then opening and closing the upper insulation cover 205 or the upper insulation cylinder 201. In this case, the bottom shell can be designed as an integral structure.

[0040] Here, we will take the bottom feeding method as an example for detailed explanation. Specifically, the bottom shell includes an intermediate cavity 103 and a lower furnace cover 104. The intermediate cavity 103 is a cylindrical tubular structure, and the lower furnace cover 104 is detachably connected to the bottom of the intermediate cavity 103.

[0041] It is understandable that flange sealing connections are preferably used between the various components of the outer furnace body 1 to ensure the airtightness of the vacuum chamber. For example, the lower end face of the upper transition cover 101 and the upper end face of the bottom shell are integrally connected with flanges, and each flange has an O-ring groove (i.e., a sealing groove) to embed an O-ring seal, thereby forming a reliable vacuum sealing interface when the flange faces are pressed together. Then, bolts are used for tightening to ensure that there is no risk of leakage at the connection. The vacuuming principle of the outer furnace body 1 is existing technology and will not be elaborated on here.

[0042] Preferably, the bottom shell, upper transition cover 101, and upper cover 102 of the outer furnace body 1 are all equipped with cooling structures. These cooling structures are used to accelerate furnace cooling after the annealing process, shorten the production cycle, and improve equipment utilization. The cooling structures include, but are not limited to, existing cooling methods such as water cooling and air cooling. The cooling structures can be implemented by creating cooling channels inside the furnace shell for the cooling medium to flow. For example, the upper transition cover 101 and / or the upper cover 102 can be configured as a stainless steel welded shell structure with double-layer water-cooling channels.

[0043] Furthermore, such as Figure 1 As shown, in some embodiments, to facilitate the handling of quartz glass components 10, the quartz glass annealing furnace further includes a frame 7 and a drive mechanism 8. The outer furnace body 1 is mounted on the frame 7, and the drive mechanism 8 is used to control the opening and closing of the vacuum chamber and the inner insulation chamber. The drive mechanism 8 includes, but is not limited to, a hydraulic cylinder, an electric push rod, or a screw drive mechanism to drive the lower furnace cover 104, the lower insulation cover 204, and the material rack 6 to move vertically upwards and downwards.

[0044] Preferably, the frame 7 adopts a steel platform structure, and the drive mechanism 8 includes a lifting mechanism (more preferably a four-screw synchronous lifting mechanism). The lifting mechanism is fixed to the steel platform of the frame 7, and its output end is connected to the lower furnace cover 104. The material rack 6 and the lower insulation cover 204 are connected to the lower furnace cover 104 through high-temperature resistant columns. Through the lifting movement of the lifting mechanism, the lower furnace cover 104, the lower insulation cover 204, and the material rack 6 move synchronously in the vertical direction, thereby realizing the opening and closing of the vacuum chamber and the inner insulation chamber.

[0045] For ease of understanding, Figure 1 The overall structural state of the vacuum chamber and inner insulation chamber when closed is demonstrated; when the output end of the elevator moves downward, it can simultaneously drive the lower furnace cover 104, the lower insulation cover 204, and the material rack 6 holding the quartz glass elements 10 to be processed to descend as a whole, so that the material rack 6 and the quartz glass elements 10 are as shown. Figure 5 The components are removed from the outer furnace body 1 and the inner furnace body 2, making it convenient for operators to complete loading and unloading operations. After the operation is completed, the entire assembly is lifted back up by a lifting platform to complete the closure and sealing of the vacuum chamber and the inner insulation chamber. The operation process is simple and labor-saving, effectively reducing the difficulty of loading and unloading large-size quartz glass components.

[0046] It is understood that in some embodiments, the quartz glass annealing furnace may not have a separate frame 7, but the outer furnace body 1 may be directly fixed to the ground foundation or a special support platform, and the quartz glass components 10 may be picked up and put down with the help of other auxiliary hoisting equipment.

[0047] It is understood that the side heating element 3 and the upper heating element 4 in this application are existing heating elements, and their specific structure, material, and arrangement can be selected according to actual process requirements. Generally, the side heating element 3 and the upper heating element 4 are usually made of high-purity graphite or other high-temperature resistant materials. Electrodes are introduced into the furnace chamber through corresponding electrode inlet holes on the outer furnace body 1 and electrically connected to the corresponding side heating element 3 and upper heating element 4. Insulation and sealing components are usually provided at the electrode inlet holes to ensure the stability of the vacuum environment inside the furnace chamber. The side heating element 3 and the upper heating element 4 can be arranged in a spiral or grid pattern to optimize the temperature field distribution inside the furnace chamber.

[0048] Generally, multiple side heating elements 3 can be configured, and these multiple side heating elements 3 are evenly distributed in a ring along the inner wall of the insulation cylinder 202 in the middle of the inner furnace body 2 to uniformly heat the circumferential side surface of the quartz glass element 10. The upper heating elements 4 are usually configured as a group, and are distributed in a circular shape inside the upper insulation cylinder 201, corresponding to the top position of the quartz glass element 10, so as to achieve independent heating of the top of the quartz glass element 10. The side heating elements 3 and the upper heating elements 4 are independently connected to the temperature control module, which can adjust the output power according to the process requirements to achieve differentiated temperature control of the two heating areas, ensure the temperature control effect of the top "hat" isolation insulation structure, and finally match the hydroxyl distribution gradient of the quartz glass element 10, thereby achieving uniform annealing, eliminating internal uneven thermal stress, and obtaining large-size quartz glass for optical components with stable performance. Based on the design of this application, in a certain experiment, during the heat preservation and cooling stage from a set temperature of 1300℃ to 1000℃, the center temperature of the quartz glass element 10 was always 10℃ lower than the edge temperature. The stress at the edge of the quartz glass element 10 decreased from the original traditional design of 7±0.5nm / cm to 0.6±0.1nm / cm; the stress at the center decreased from the original 0.7±0.1nm / cm to 0.2±0.1nm / cm; and the stress difference from the edge to the center decreased from the original 6.4nm to 0.5nm, significantly improving the stress uniformity.

[0049] It's important to understand that the term "and / or" describes a relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone. In this article, the symbol " / " indicates that the related objects are in an "or" relationship, such as A / B meaning A or B.

[0050] It should be understood that expressions such as "comprising" and "may include" as used in this application indicate the existence of the disclosed functions, operations, or constituent elements, and do not limit one or more additional functions, operations, and constituent elements. In this application, terms such as "comprising" and / or "having" may be interpreted as indicating a specific characteristic, number, operation, constituent element, component, or combination thereof, but should not be interpreted as excluding the existence or possibility of adding one or more other characteristics, numbers, operations, constituent elements, components, or combinations thereof.

[0051] It should be understood that the terms “center,” “upper,” “lower,” “front,” “rear,” “left,” “right,” “vertical,” “horizontal,” “inner,” “outer,” “clockwise,” “counterclockwise,” “axial,” “radial,” and “circumferential” indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0052] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0053] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0054] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A quartz glass annealing furnace characterized by comprising: include: The outer furnace body (1) has an openable and closable vacuum chamber inside. The inner furnace body (2) is disposed within the vacuum cavity and includes a lower cavity and an upper insulation cylinder (201). The upper insulation cylinder (201) is fixedly disposed at the top center of the lower cavity, and together with the lower cavity, they form an openable and closable inner insulation cavity for accommodating the quartz glass element (10). The upper insulation cylinder (201) is closed at the top and open at the bottom. The lower end of the upper insulation cylinder (201) extends downward to form a clearance fit with the top circumferential edge of the quartz glass element (10). The upper end of the upper insulation cylinder (201) extends upward and protrudes from the top of the lower cavity. The thermal resistance of the upper part of the inner furnace body (2) increases gradually from the inside to the outside along the radial direction of the inner furnace body (2). Side heating element (3), the side heating element (3) is mounted on the inner wall of the lower cavity and distributed along the circumference of the quartz glass element (10); The upper heating element (4) is mounted inside the upper insulation cylinder (201) and located above the quartz glass element (10).

2. The quartz glass annealing furnace as claimed in claim 1, wherein The lower cavity includes: The central insulation cylinder (202) is a hollow tubular structure; Insulating base (203), the insulating base (203) is sealed to the bottom opening of the middle insulating cylinder (202), and a through lower mounting port is provided at the center of the lower end face of the insulating base (203); The lower insulation cover (204) is detachably and sealed to the lower mounting port; The upper insulation cover (205) covers and connects to the top opening of the middle insulation cylinder (202). The upper insulation cover (205) has a through upper mounting port at the center of its upper end face. The upper insulation cylinder (201) is interference-fitted to the upper mounting port.

3. The quartz glass annealing furnace as claimed in claim 2, wherein The thermal resistance of the upper insulation cylinder (201), the upper insulation cover (205), and the middle insulation cylinder (202) increases sequentially.

4. The quartz glass annealing furnace as claimed in claim 1, wherein The upper heat insulation cylinder (201) is coaxial with the quartz glass element (10), and the lower end face of the upper heat insulation cylinder (201) is close to the upper circumferential edge of the quartz glass element (10), with an axial gap of 5mm to 15mm between them.

5. The quartz glass annealing furnace as claimed in claim 1, wherein The outer furnace body (1) includes: The bottom shell has a chamber with an opening at the top; The upper transition cover (101) has its lower end sealed to the top opening of the bottom shell, and its upper end gradually narrows upward to form a tapered transition section with an upper mounting hole; the upper insulation cylinder (201) passes through the upper mounting hole; The upper cover (102) has its lower end sealed to the top of the upper transition cover (101), and its upper end extends upward to the top of the upper insulation cylinder (201). The upper end of the upper cover (102) is a closed structure.

6. The quartz glass annealing furnace as described in claim 5, characterized in that, The bottom shell includes an intermediate cavity (103) and a lower furnace cover (104). The intermediate cavity (103) is a hollow tubular structure. The top of the intermediate cavity (103) is sealed to the upper transition cover (101). The lower furnace cover (104) is detachably connected to the bottom of the intermediate cavity (103).

7. The quartz glass annealing furnace as described in claim 5, characterized in that, Cooling structures are provided in the bottom shell, the upper transition cover (101), and the upper cover (102).

8. The quartz glass annealing furnace according to any one of claims 1-7, characterized in that, The inner wall of the outer furnace body (1) is provided with a plurality of support brackets (5) circumferentially. One end of each support bracket (5) is connected to the inner wall of the outer furnace body (1), and the other end extends inward to support the bottom of the inner furnace body (2).

9. The quartz glass annealing furnace according to any one of claims 1-7, characterized in that, The quartz glass annealing furnace also includes a material rack (6), through which the quartz glass element (10) is mounted in the inner insulation cavity.

10. The quartz glass annealing furnace according to any one of claims 1-7, characterized in that, The quartz glass annealing furnace also includes a frame (7) and a drive mechanism (8). The outer furnace body (1) is mounted on the frame (7), and the drive mechanism (8) is used to control the opening and closing of the vacuum chamber and the inner heat preservation chamber.

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