Optical glass mold pressing method based on multi-zone non-isothermal gradient heating

Abstract

The present application relates to the technical field of optical glass manufacturing, and discloses an optical glass mold pressing forming method based on multi-zone non-isothermal gradient heating. The method divides the heating system of the mold pressing forming area into multiple independent temperature control zones, actively constructs a preset non-isothermal gradient temperature field that is geometrically suitable for the component before pressure forming, and guides the viscosity distribution of the glass material. In the pressure forming process, the temperature data of each temperature zone are collected in real time and compared with the dynamic target gradient, the heating power is adjusted based on the deviation closed loop, the actual temperature field intelligently follows the preset gradient, and the material flow filling is optimized. After forming, a gradient annealing cooling program with partition differentiation is executed, different cooling rates are set according to the thickness or stress risk of the region, and the internal stress is sequentially released. The present application actively and accurately regulates and controls the temperature field in the whole forming process, can effectively improve the surface shape precision of the optical component, reduce the residual stress and improve the surface quality.

Description

Technical Field

[0001] This invention relates to the field of optical glass manufacturing technology, specifically to an optical glass molding method based on multi-region non-isothermal gradient heating. Background Technology

[0002] Optical glass molding technology is a key process for achieving mass production and low-cost manufacturing of aspherical, free-form, and microstructure optical components. This technology directly obtains the desired optical surface shape by softening a glass preform at high temperature and then pressing it into shape in a precision mold, avoiding traditional grinding and polishing processes.

[0003] However, the existing mainstream isothermal molding process has significant technical bottlenecks. In this process, the mold and glass are uniformly heated to a constant temperature above the glass transition temperature, followed by pressurization and cooling. Due to the complex shape and uneven thickness distribution of optical components (especially aspherical, high-sag, or thin-walled components), there are inherent differences in viscosity, flow stress, and cooling shrinkage rate of different parts of the glass material under a uniform temperature field. This directly leads to uneven material flow during molding, which easily generates residual stress concentration inside the component and causes defects such as surface contour deviations (e.g., spherical aberration, eccentricity), surface imperfections (e.g., wrinkles, orange peel effect), and insufficient edge filling. Residual stress not only affects the short-term optical performance and long-term environmental stability of the component, but may also lead to cracking during use.

[0004] Therefore, this invention proposes an optical glass molding method based on multi-region non-isothermal gradient heating. Summary of the Invention

[0005] The purpose of this invention is to provide a method for molding optical glass based on multi-region non-isothermal gradient heating, thereby solving the above-mentioned technical problems: The objective of this invention can be achieved through the following technical solutions: An optical glass molding method based on multi-region non-isothermal gradient heating, the method comprising the following steps: S1. Place the optical glass blank into the cavity of the lower mold; S2. Start the heating system, which can independently heat multiple areas of the forming area; control the temperature of each area to form a preset non-isothermal gradient temperature field in the forming area including the upper mold, lower mold and glass blank; S3. When the non-isothermal gradient temperature field reaches a stable state, drive the upper mold to move downwards to press and form, and dynamically adjust the temperature of each area during the pressing process to maintain or change the temperature gradient. S4. After the pressure holding stage is completed, each area is controlled to undergo gradient annealing at different cooling rates, and then cooled to the demolding temperature. S5. Open the mold and remove the formed optical glass component.

[0006] As a further description of the technical solution of the present invention, the heating system in step S2 includes a heating unit, a temperature detection unit, a temperature control unit and a heat preservation unit. The heating unit is divided into at least three independent heating areas along the radial and axial directions of the mold cavity. Temperature isolation plates are set between each area. Each area corresponds to an independent heating module. The temperature control unit is electrically connected to the heating unit and the temperature detection unit to realize closed-loop temperature control.

[0007] As a further description of the technical solution of the present invention, the working process of dynamically adjusting the temperature of each temperature zone in S3 includes: S31. Number all independent heating units sequentially as follows: 1, 2, ..., n; S32. The temperature detection unit sequentially acquires the temperature change data of all independent heating units over time and processes the acquired data. S33. Compare the processed temperature measurement data with the preset target temperature gradient distribution that changes over time to determine the temperature control deviation of each zone. Based on the temperature control deviation, the output power of the corresponding independent heating module is adjusted in real time so that the actual temperature gradient of the molding area follows or approaches the preset target temperature gradient distribution during the pressurization process.

[0008] As a further description of the technical solution of the present invention, the working process of S32 includes: Data filtering: The Kalman filter algorithm is used to filter the raw temperature data. Outlier removal: The temperature threshold range for each heating zone is preset. The 3σ criterion is used to judge outliers in the filtered temperature data. If the data of a certain collection point deviates from the normal temperature range of the zone by more than 3σ, it is judged as an outlier. The outlier is replaced by the average value of the three adjacent valid collection points to avoid temperature control deviation caused by outlier data. Data calibration: Based on the preset calibration curve of the temperature detection unit, the temperature data after removing outliers is linearly calibrated to compensate for the sensor's own error and the impact of ambient temperature on the acquisition accuracy. Data normalization and synchronization: The calibrated temperature data of each heating zone is normalized to the same data level. At the same time, the temperature data of multiple zones is synchronized and aligned based on the acquisition timestamp to ensure the temporal consistency of temperature data in each zone, providing accurate data support for the coordinated control of temperature gradient.

[0009] As a further description of the technical solution of the present invention, the working process of S33 includes: Obtain the temperature change data of the i-th region over time within a set time period, and use the formula... Calculate the temperature compliance coefficient for the i-th region. Where i belongs to n, and y is the number of temperature sampling points in the i-th region within a set time period. Let x be the measured value of the x-th sampling point in the i-th region within a given time period. The standard value of the x-th sampling point in the i-th region within the preset time period of the system; Based on the temperature compliance coefficient of the i-th region It determines whether the temperature in the area deviates from the preset gradient requirement and generates a power adjustment command accordingly.

[0010] As a further description of the technical solution of the present invention, The temperature compliance coefficient of the i-th region With preset threshold , Comparison: If ∈[ If the temperature of the i-th region is not adjusted, the heating power will not be adjusted. ∉[ If ], then the heating power for the i-th region is adjusted.

[0011] The heating power adjustment value is calculated using the following formula: Where K is the power conversion factor. Let i be the spatial volume corresponding to the i-th region. The system's preset standard volume; when < When, increase the heating power, when > Reduce heating power.

[0012] As a further description of the technical solution of the present invention, the working process of S4 includes: S41. When the pressure sensor detects a signal indicating the end of the molding pressure holding stage, and the average temperature of all temperature zones is within the set annealing start temperature range. Within this timeframe, the system confirms that it has entered the gradient annealing stage; among which, Not lower than the strain point temperature of the glass material used. Not exceeding its annealing point temperature; S42. Pre-set a non-linear cooling temperature-time curve for each independent temperature zone. The curve shows the cooling rate. For the control core, the initial cooling rate Based on the estimated stress concentration or thickness of the corresponding components. Define and satisfy the following relationship: Where A, B, and C are material-related empirical coefficients, and the ratio of the initial cooling rate in different temperature ranges is ensured to be within a preset range; S43. When the temperature of all temperature zones drops below the set first conversion temperature, the cooling mode is switched to the first stage of uniform slow cooling, and each temperature zone adopts a uniform and low cooling rate; when the temperature drops further to the set second conversion temperature, it switches to the second stage of controllable rapid cooling or natural cooling until the safe demolding temperature is reached, and the gradient annealing stage ends.

[0013] The beneficial effects of this invention: The multi-region non-isothermal gradient heating molding method provided by this invention has the core beneficial effect of systematically breaking through the process bottleneck of traditional isothermal molding through active and dynamic temperature field control throughout the entire process. By constructing a preset gradient temperature field that matches the geometry of the component, this invention can actively guide the glass material to preferentially fill the areas that are difficult to form, effectively eliminating insufficient filling, wrinkles, and surface contour deviations caused by uneven flow, and significantly improving the contour accuracy and reproducibility of the optical surface. In the pressure forming stage, through real-time monitoring and feedback of dynamic temperature adjustment, the temperature gradient is intelligently followed and adapted to the material flow, further optimizing the forming process and widening the process window. In the annealing and cooling stage, through a zoned and differentiated gradient annealing strategy, the orderly and directional release of internal stress is achieved, reducing the residual stress of the component to an extremely low level, greatly enhancing its optical uniformity, long-term stability, and resistance to environmental failure. Therefore, this invention can simultaneously achieve high surface accuracy, low internal stress, and excellent surface quality, and is particularly suitable for the efficient and high-yield manufacturing of complex aspherical, free-form, and thin-walled high-precision optical glass components. Attached Figure Description

[0014] The invention will now be further described with reference to the accompanying drawings.

[0015] Figure 1 This is a partial flowchart of the optical glass molding method based on multi-region non-isothermal gradient heating according to the present invention. Detailed Implementation

[0016] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] Please see Figure 1 As shown, the present invention provides a method for molding optical glass based on multi-region non-isothermal gradient heating, the method comprising the following steps: S1. Place the optical glass blank into the cavity of the lower mold; S2. Start the heating system, which can independently heat multiple areas of the forming area; control the temperature of each area to form a preset non-isothermal gradient temperature field in the forming area including the upper mold, lower mold and glass blank; S3. When the non-isothermal gradient temperature field reaches a stable state, drive the upper mold to move downwards to press and form, and dynamically adjust the temperature of each area during the pressing process to maintain or change the temperature gradient. S4. After the pressure holding stage is completed, each area is controlled to undergo gradient annealing at different cooling rates, and then cooled to the demolding temperature. S5. Open the mold and remove the formed optical glass component.

[0018] Through the above technical solution, this invention first places the pre-fabricated optical glass blank into the lower mold cavity, and then activates a heating system with multi-zone independent temperature control capability. Physically, this system is divided into at least three thermally isolated independent temperature control zones along the radial and axial directions of the mold cavity. Each zone is equipped with an independent heating module and temperature sensor, and closed-loop control is achieved by a central control unit. In the initial heating stage, instead of pursuing the uniform temperature of traditional processes, a differentiated target temperature is set for each zone based on the geometry, thickness distribution, and expected material flow path of the target optical element. This pre-forms a stable and controllable non-isothermal gradient temperature field within the entire forming area, including the upper mold, lower mold, and glass blank. This gradient field ensures that the glass blank has a preset viscosity distribution matching the forming structure before pressurization, laying the foundation for subsequent intelligent filling.

[0019] Then, once the gradient temperature field reaches a steady state, the pressurization and molding stage begins. At this point, the upper mold applies pressure downwards, driving the glass material from the high-temperature, low-viscosity region to preferentially flow towards the low-temperature, high-viscosity or difficult-to-fill region. Crucially, the pressurization process is not conducted under a fixed temperature gradient, but rather a dynamically coupled process. The control system continuously collects real-time temperature data from each zone. After precise preprocessing including Kalman filtering, outlier removal, sensor calibration, and data synchronization, this data is compared with a preset, time-varying target temperature gradient distribution. By calculating the temperature control deviation in each zone, the system adjusts the output power of the corresponding heating modules in real time, dynamically maintaining or changing the temperature gradient distribution of the entire region as planned, ensuring it always matches the real-time deformation state and flow requirements of the glass material.

[0020] Then, after the molding pressure is maintained, the system, after determining that the average temperature is within a suitable range between the strain point and annealing point of the glass material, does not immediately cool uniformly. Instead, it presets a non-linear cooling curve for each independent temperature zone. The initial cooling rate of each zone is set differently according to the estimated stress concentration or geometric thickness of the corresponding component; for example, a slower cooling rate is used for thick-walled or stress-concentration areas. In the early stage of annealing, each zone undergoes non-uniform cooling according to its own cooling curve to achieve gradient annealing, thereby releasing the internal stress generated during molding in an orderly and directional manner. When the temperature of all zones drops below the first transition temperature (below the glass transition temperature), it switches to uniform slow cooling at the same rate for all zones in the first stage to further equalize the internal stress. Finally, when the temperature drops to the second transition point, which is close to the safe demolding temperature, it switches to rapid cooling mode until demolding. After mold opening, an optical glass component with low internal stress, high surface accuracy, and good surface quality can be obtained. The entire process actively designs the temperature field across the entire chain, from preset gradient heating to dynamic gradient forming to gradient annealing and cooling, replacing the traditional passive uniform temperature control. This enables precise control over the complex coupling behavior of heat, force, and flow during glass forming.

[0021] In step S2, the heating system includes a heating unit, a temperature detection unit, a temperature control unit, and a heat preservation unit. The heating unit is divided into at least three independent heating zones along the radial and axial directions of the mold cavity. Temperature isolation plates are set between each zone. Each zone corresponds to an independent heating module. The temperature control unit is electrically connected to the heating unit and the temperature detection unit to achieve closed-loop temperature control.

[0022] The process of dynamically adjusting the temperature of each temperature zone in S3 includes: S31. Number all independent heating units sequentially as follows: 1, 2, ..., n; S32. The temperature detection unit sequentially acquires the temperature change data of all independent heating units over time and processes the acquired data. S33. Compare the processed temperature measurement data with the preset target temperature gradient distribution that changes over time to determine the temperature control deviation of each zone. Based on the temperature control deviation, the output power of the corresponding independent heating module is adjusted in real time so that the actual temperature gradient of the molding area follows or approaches the preset target temperature gradient distribution during the pressurization process.

[0023] Through the above technical solution, the system first logically numbers all independent heating modules to establish a control index. Then, the temperature detection unit sequentially collects the time-series temperature data of the corresponding areas of each module. After preliminary processing of the acquired raw data, the system compares the processed actual temperature measurement value with a preset, dynamically changing target temperature gradient distribution model in real time. This comparison calculates the real-time temperature control deviation for each independent temperature zone. This deviation directly reflects the degree of deviation between the current actual temperature field and the ideal gradient state. Based on this deviation, the temperature control unit instantly and accurately adjusts the output power of the corresponding independent heating module, forming a continuous measurement-comparison-adjustment feedback loop. The fundamental purpose of this control process is to enable the actual comprehensive temperature gradient formed by the combined effects of the temperatures of each zone within the molding area to actively track, follow, or infinitely approximate the preset dynamic target gradient that adapts to the flow and deformation of the glass material throughout the entire pressurization molding process. This achieves intelligent coordination between the temperature field and the material deformation field, optimizing the molding quality.

[0024] The working process of S32 includes: Data filtering: The Kalman filter algorithm is used to filter the raw temperature data to remove random noise caused by electromagnetic interference and sensor jitter during the acquisition process. The filtering window is set to 3-5 acquisition cycles to ensure the smoothness of the filtered temperature data, while preserving the true trend of temperature gradient change and avoiding over-filtering that leads to temperature response lag. Outlier removal: The temperature threshold range for each heating zone is preset. The 3σ criterion is used to judge outliers in the filtered temperature data. If the data of a certain collection point deviates from the normal temperature range of the zone by more than 3σ, it is judged as an outlier. The outlier is replaced by the average value of the three adjacent valid collection points to avoid temperature control deviation caused by outlier data. Data calibration: Based on the preset calibration curve of the temperature detection unit, linear calibration is performed on the temperature data after outlier removal to compensate for sensor errors and the influence of ambient temperature on acquisition accuracy; the calibration formula is T. 校准 =k×T 集 +b (where k is the calibration coefficient, ranging from 1.002 to 1.005, and b is the calibration constant, ranging from -0.3 to 0.3℃), ensuring that the deviation between the calibrated data and the actual temperature is ≤ ±0.1℃; Data normalization and synchronization: The calibrated temperature data of each heating zone is normalized to the same data level. At the same time, the temperature data of multiple zones is synchronized and aligned based on the acquisition timestamp to ensure the temporal consistency of temperature data in each zone, providing accurate data support for the coordinated control of temperature gradient.

[0025] The working process of S33 includes: Obtain the temperature change data of the i-th region over time within a set time period, and use the formula... Calculate the temperature compliance coefficient for the i-th region. Where i belongs to n, and y is the number of temperature sampling points in the i-th region within a set time period. Let x be the measured value of the x-th sampling point in the i-th region within a given time period. The standard value of the x-th sampling point in the i-th region within the preset time period of the system; Based on the temperature compliance coefficient of the i-th region It determines whether the temperature in the area deviates from the preset gradient requirement and generates a power adjustment command accordingly.

[0026] The temperature compliance coefficient of the i-th region With preset threshold , Comparison: If ∈[ If the temperature of the i-th region is not adjusted, the heating power will not be adjusted. ∉[ If ], then the heating power for the i-th region is adjusted.

[0027] The heating power adjustment value is calculated using the following formula: Where K is the power conversion factor. Let i be the spatial volume corresponding to the i-th region. The system's preset standard volume; when < When, increase the heating power, when > Reduce heating power.

[0028] Using the above technical solution, the system first collects a series of discrete temperature sampling points for the i-th temperature zone within a set time period, and then... Calculate the temperature compliance coefficient for the i-th region. The essence of this formula is to calculate the arithmetic mean of the deviations between the measured values ​​at each sampling point and the preset standard values ​​at the corresponding times within that time period, thereby representing a scalar value. This comprehensively characterizes the degree to which the overall temperature in the region deviates from the target trajectory. Subsequently, the system will... With the preset threshold range [ Compare and make logical judgments: If If the temperature falls within this tolerance range, the temperature control is considered acceptable, and the heating power is not adjusted; if... If the value exceeds this range, a power adjustment mechanism is triggered. The specific calculation method and directional logic for the power adjustment amount are then further defined. Adjustment Amount From the formula Confirmed. This formula indicates that the adjustment range is related to... Deviation from the midpoint of the threshold interval The distance is proportional to the absolute value, and the ratio of the regional spatial volume to the standard volume is introduced as a spatial weighting factor, while the power conversion coefficient K is used for dimensional transformation and overall scaling. Simultaneously, the system... The direction of deviation determines the direction of adjustment: when < Increase heating power when the overall temperature is low. > When the overall temperature is too high, the heating power is reduced. This mechanism constitutes a closed-loop control strategy that combines continuous temperature deviation assessment, threshold judgment, and quantitative power adjustment that comprehensively considers spatial factors.

[0029] The working process of S4 includes: S41. When the pressure sensor detects a signal indicating the end of the molding pressure holding stage, and the average temperature of all temperature zones is within the set annealing start temperature range. Within this timeframe, the system confirms that it has entered the gradient annealing stage; among which, Not lower than the strain point temperature of the glass material used. Not exceeding its annealing point temperature; S42. Pre-set a non-linear cooling temperature-time curve for each independent temperature zone. The curve shows the cooling rate. For the control core, the initial cooling rate Based on the estimated stress concentration or thickness of the corresponding components. Define and satisfy the following relationship: Where A, B, and C are material-related empirical coefficients, and the ratio of the initial cooling rate in different temperature ranges is ensured to be within a preset range; S43. When the temperature of all temperature zones drops below the set first conversion temperature, the cooling mode is switched to the first stage of uniform slow cooling, and each temperature zone adopts a uniform and low cooling rate; when the temperature drops further to the set second conversion temperature, it switches to the second stage of controllable rapid cooling or natural cooling until the safe demolding temperature is reached, and the gradient annealing stage ends.

[0030] The above technical solution begins when the system confirms the end of pressurization and that the average temperature is within a suitable range between the annealing point and strain point of the glass material. Subsequently, the system presets a personalized nonlinear cooling curve for each independent temperature zone, with the cooling rate as the core control parameter. The key design element lies in the initial cooling rate of each zone. It is not arbitrarily set, but rather based on the estimated stress concentration or geometric thickness of the corresponding components. Differential calculations are basically performed by following these principles. The relationship between j and n allows thick-walled or high-stress-risk areas to begin cooling at a slower rate, achieving gradient management of stress release. The annealing process is divided into two stages: First, each zone cools independently according to its predetermined curve, forming a gradient annealing field; when the temperature of all zones drops below the first transition temperature, it transitions to uniform slow cooling at a uniform rate across all zones in the first stage to further balance the internal temperature difference and stress; finally, after the temperature drops to the second transition point, it is rapidly cooled to the safe demolding temperature, completing the entire controlled stress relaxation process.

[0031] It should be noted that the formulas in this application are all dimensionless and numerical calculations. The formulas are obtained by software simulation based on a large amount of data and are the closest to the real situation. The threshold ranges, standard ranges and coefficients involved in this application are all empirical values ​​and are selected by those skilled in the art according to the actual situation.

[0032] For ease of understanding, the following is a specific embodiment of the present invention: A BK7 glass aspherical lens with an aperture of Φ30mm, a center thickness of 5mm, and an edge thickness of 2.5mm is manufactured.

[0033] 1. Equipment and Material Preparation Molding equipment: A precision glass molding machine is used, and its mold heating system has been modified. The heaters for the upper and lower molds, according to the design of this invention, are divided into five independent concentric ring-shaped temperature control zones (A1 to A5), radiating outwards from the center of the mold. Each zone is equipped with an independent armored thermocouple (temperature detection unit) and a miniature infrared heating rod (heating unit), controlled by a multi-channel high-precision temperature controller (temperature control unit). Each zone is filled with ceramic fiber as a thermal insulation structure.

[0034] Mold: The upper and lower aspherical mold cores are made of ultra-hard alloy material and are coated with a precious metal anti-oxidation coating.

[0035] Glass material: Optical glass BK7 is selected, with the following characteristics: glass transition temperature 557℃, annealing point 545℃, strain point 510℃. It is pre-melted into a precision annealed spherical preform (blank) of Φ30mm×5mm.

[0036] 2. Implementation Steps S1. After ultrasonic cleaning and drying, the BK7 glass preform is precisely placed in the center of the lower mold cavity.

[0037] S2. To compensate for the difficulty in edge cooling and filling caused by the material flowing from the center to the edge during molding, a positive temperature gradient field that increases from the center to the edge is preset. The molding process is simulated using finite element simulation software, and the steady-state target temperature of each zone is determined as follows: Zone A1 (center): 575℃; Zone A2: 580℃; Zone A3: 585℃; Zone A4: 590℃; Zone A5 (outermost ring): 595℃.

[0038] Heating Execution: The multi-zone heating system is activated. The temperature controller performs closed-loop control based on the set values ​​for each zone. After approximately 30 minutes, the system detects that the temperature fluctuation in each zone is less than ±0.5℃ and remains stable for 5 minutes, indicating that the non-isothermal gradient temperature field has reached a stable state. At this point, the glass preform has softened as a whole, and the viscosity decreases sequentially from the center to the edge.

[0039] S3, Gradient Pressure Molding and Dynamic Control: Pressurization: The upper mold descends at a speed of 0.5 mm / min to contact the glass and applies an initial pressure of 50 N.

[0040] Dynamic temperature control: Entering the main pressurization stage (pressure rises to 5000N). During this process, the control logic of the temperature control unit is as follows: Data Acquisition and Processing: Temperature data for each zone is collected every 0.5 seconds. After Kalman filtering and calibration, reliable data is obtained. .

[0041] Calculation and Decision-Making: Calculate the temperature compliance coefficient for each zone using a 10-second control cycle. (That is, the average deviation between the measured temperature and the preset target temperature over the past 10 seconds). For example, at a certain moment, the S5 value of the detected A5 area (edge) is lower than its lower threshold limit. This indicates that the temperature in the edge region is low, which may lead to insufficient material flowability.

[0042] Power Adjustment: Calculate the required power adjustment value ΔP for area A5. Because... < The system determines that the heating power needs to be increased. The adjustment amount ΔP is related to... The degree of deviation from the threshold is directly proportional to the relative volume of zone A5. The thermostat then slightly increases the power output of the heating rod in zone A5, causing its temperature to rise back to the target range.

[0043] Continuous adaptation: Throughout the pressurization process (approximately 3 minutes), the system continuously performs this feedback-based dynamic adjustment to ensure that the actual temperature gradient always serves the optimal material flow and filling, effectively avoiding the defect of incomplete edge filling.

[0044] S4. After the pressure holding period ends, the system detects an average temperature of 590℃ (between the annealing point and strain point of BK7), triggering the gradient annealing procedure.

[0045] Different initial cooling rates are set for each zone. Considering the lens is thinner at the edges and thicker at the center, a strategy of slightly faster cooling at the edges and slightly slower cooling at the center is adopted to balance shrinkage stress. Preset: Zone A5 =15℃ / min, A1 zone =10℃ / min, rate gradient distribution in the middle zone.

[0046] The system controls each zone to cool down according to a preset nonlinear cooling curve. During the process of cooling from 590℃ to 500℃ (the first transition temperature), each zone cools asynchronously, forming gradient annealing.

[0047] When the temperature of all zones drops below 500℃, the first stage of uniform slow cooling begins, with all zones being cooled at a rate of 5℃ / min to 400℃ (the second transition temperature).

[0048] The process then transitions to the second stage of natural cooling, where the heater is turned off and the mold is allowed to cool naturally to a safe demolding temperature below 150°C under the protection of inert gas.

[0049] S5. Open the mold and use an automated part-removing arm to remove the molded lens.

[0050] 3. Test results: Surface shape accuracy: Using a profilometer, the surface shape error of the aspherical surface is less than 0.5 micrometers, which meets the design requirements.

[0051] Residual stress: Detected using a polarimeter, the birefringence value is less than 10 nm / cm, indicating extremely low internal stress.

[0052] Surface quality: Under an optical microscope, there are no flow defects such as wrinkles or orange peel, and the surface is smooth.

[0053] The foregoing has provided a detailed description of one embodiment of the present invention, but this description is merely a preferred embodiment and should not be construed as limiting the scope of the invention. All equivalent variations and modifications made within the scope of the claims of this invention should still fall within the patent coverage of this invention.

Claims

1. A method for molding optical glass based on multi-region non-isothermal gradient heating, characterized in that, The method includes the following steps: S1. Place the optical glass blank into the cavity of the lower mold; S2. Start the heating system, which can independently heat multiple areas of the forming area; control the temperature of each area to form a preset non-isothermal gradient temperature field in the forming area including the upper mold, lower mold and glass blank; S3. When the non-isothermal gradient temperature field reaches a stable state, drive the upper mold to move downwards to press and form, and dynamically adjust the temperature of each area during the pressing process to maintain or change the temperature gradient. S4. After the pressure holding stage is completed, each area is controlled to undergo gradient annealing at different cooling rates, and then cooled to the demolding temperature. S5. Open the mold and remove the formed optical glass component.

2. The optical glass molding method based on multi-region non-isothermal gradient heating according to claim 1, characterized in that, In step S2, the heating system includes a heating unit, a temperature detection unit, a temperature control unit, and a heat preservation unit. The heating unit is divided into at least three independent heating zones along the radial and axial directions of the mold cavity. Temperature isolation plates are set between each zone. Each zone corresponds to an independent heating module. The temperature control unit is electrically connected to the heating unit and the temperature detection unit to achieve closed-loop temperature control.

3. The optical glass molding method based on multi-region non-isothermal gradient heating according to claim 2, characterized in that, The process of dynamically adjusting the temperature of each temperature zone in S3 includes: S31. Number all independent heating units sequentially as follows: 1, 2, ..., n; S32. The temperature detection unit sequentially acquires the temperature change data of all independent heating units over time and processes the acquired data. S33. Compare the processed temperature measurement data with the preset target temperature gradient distribution that changes over time to determine the temperature control deviation of each zone. Based on the temperature control deviation, the output power of the corresponding independent heating module is adjusted in real time so that the actual temperature gradient of the molding area follows or approaches the preset target temperature gradient distribution during the pressurization process.

4. The optical glass molding method based on multi-region non-isothermal gradient heating according to claim 1, characterized in that, The working process of S32 includes: Data filtering: The Kalman filter algorithm is used to filter the raw temperature data; Outlier removal: The temperature threshold range for each heating zone is preset. The 3σ criterion is used to judge outliers in the filtered temperature data. If the data of a certain collection point deviates from the normal temperature range of the zone by more than 3σ, it is judged as an outlier. The outlier is replaced by the average value of the three adjacent valid collection points to avoid temperature control deviation caused by outlier data. Data calibration: Based on the preset calibration curve of the temperature detection unit, the temperature data after removing outliers is linearly calibrated to compensate for the sensor's own error and the impact of ambient temperature on the acquisition accuracy. Data normalization and synchronization: The calibrated temperature data of each heating zone is normalized to the same data level. At the same time, the temperature data of multiple zones is synchronized and aligned based on the acquisition timestamp to ensure the temporal consistency of temperature data in each zone, providing accurate data support for the coordinated control of temperature gradient.

5. The optical glass molding method based on multi-region non-isothermal gradient heating according to claim 4, characterized in that, The working process of S33 includes: Obtain the temperature change data of the i-th region over time within a set time period, and use the formula... Calculate the temperature compliance coefficient for the i-th region. Where i belongs to n, and y is the number of temperature sampling points in the i-th region within a set time period. Let x be the measured value of the x-th sampling point in the i-th region within a given time period. The standard value of the x-th sampling point in the i-th region within the preset time period of the system; Based on the temperature compliance coefficient of the i-th region It determines whether the temperature in the area deviates from the preset gradient requirement and generates a power adjustment command accordingly.

6. The optical glass molding method based on multi-region non-isothermal gradient heating according to claim 5, characterized in that, The temperature compliance coefficient of the i-th region With preset threshold , Comparison: If ∈[ If the temperature of the i-th region is not adjusted, the heating power will not be adjusted. ∉[ If the temperature of the i-th region is adjusted, the heating power will be adjusted accordingly. The heating power adjustment value is calculated using the following formula: Where K is the power conversion factor. Let i be the spatial volume corresponding to the i-th region. The system's preset standard volume; when < When, increase the heating power, when > Reduce heating power.

7. The optical glass molding method based on multi-region non-isothermal gradient heating according to claim 1, characterized in that, The working process of S4 includes: S41. When the pressure sensor detects a signal indicating the end of the molding pressure holding stage, and the average temperature of all temperature zones is within the set annealing start temperature range. Within this timeframe, the system confirms that it has entered the gradient annealing stage; among which, Not lower than the strain point temperature of the glass material used. Not exceeding its annealing point temperature; S42. Pre-set a non-linear cooling temperature-time curve for each independent temperature zone. The curve shows the cooling rate. For the control core, the initial cooling rate Based on the estimated stress concentration or thickness of the corresponding components. Define and satisfy the following relationship: Where A, B, and C are material-related empirical coefficients, and the ratio of the initial cooling rate in different temperature ranges is ensured to be within a preset range; S43. When the temperature of all temperature zones drops below the set first conversion temperature, the cooling mode is switched to the first stage of uniform slow cooling, and each temperature zone adopts a uniform and low cooling rate; when the temperature drops further to the set second conversion temperature, it switches to the second stage of controllable rapid cooling or natural cooling until the safe demolding temperature is reached, and the gradient annealing stage ends.

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