Hot bending mold, hot bending apparatus, and molding method

Abstract

The application provides a hot bending mold, a hot bending device and a forming method, and relates to the field of glass hot bending. The hot bending mold comprises a lower mold assembly, an upper mold assembly and a temperature control assembly embedded in the lower mold assembly; the thermal expansion coefficients of the materials of the lower mold assembly and the upper mold assembly are greater than the thermal expansion coefficient of the glass to be processed; the lower mold assembly comprises a lower mold base, a positioning core and an auxiliary positioning insert block, the lower mold base is provided with a positioning groove and an annular groove; the positioning core is inserted into the positioning groove after penetrating through the inner hole of the glass to be processed, and the auxiliary positioning insert block is attached to the inner wall of the cavity and the outer wall of the glass to be processed; the upper mold assembly comprises an upper frame mold, an annular forming mold core and a guide core, and the upper frame mold is pressed on the surface of the lower mold base with the cavity; the side wall of the annular forming mold core is arc-shaped and is pressed on the deformation of the glass to be processed; and the guide core is inserted into the positioning groove after penetrating through the inner hole of the glass to be processed. The hot bending mold provided by the application solves the problems of easy cracking and edge collapse of the glass round hole hot bending ring, mold printing and low yield in the prior art.

Description

Technical Field

[0001] This application relates to the field of glass hot bending, and more specifically, to a hot bending mold, hot bending equipment, and forming method. Background Technology

[0002] Currently, in glass hot bending technology, the molds used for processing round-hole glass into ring structures mainly employ general-purpose mold structures. The core material of these molds is ordinary graphite. During the hot bending process, an integral heating method is used, and the main body of the mold is a fixed structure. Its positioning structure, temperature control system, and forming core all follow the general design scheme of conventional glass hot bending. When using the above-mentioned general-purpose molds for hot bending round-hole glass, the following problems exist: large deviations in the uniformity of the circumferential temperature field during the forming process, and concentrated internal stress in the glass, leading to defects such as cracking, edge chipping, and mold marks; poor roundness and surface roughness of the processed ring-shaped 3D glass, requiring secondary correction processing, increasing process material consumption and costs; and low yield of the processed ring-shaped 3D glass. Summary of the Invention

[0003] The purpose of this invention is to provide a hot bending mold, hot bending equipment, and forming method to alleviate the technical problems of easy cracking and edge chipping of hot-bent glass circular holes, mold marks, and low yield in the prior art.

[0004] To solve the above-mentioned technical problems, the technical solution provided by the present invention is as follows: In a first aspect, the hot bending mold provided by the present invention includes a lower mold assembly, an upper mold assembly, and a temperature control assembly; The coefficient of thermal expansion of the materials of the lower mold assembly and the upper mold assembly is greater than that of the glass to be processed. The lower mold assembly includes a lower mold base, a positioning core, and an auxiliary positioning insert. The cavity of the lower mold base is provided with a positioning groove and an annular groove, and the annular groove surrounds the outer periphery of the positioning groove. The positioning core is used to pass through the inner hole of the glass to be processed and then be inserted into the positioning groove. The auxiliary positioning insert is used to fit against the inner wall of the cavity and the outer wall of the glass to be processed. The upper mold assembly includes an upper frame mold, an annular forming mold core, and a guide core. The upper frame mold is used to press against the surface of the lower mold base having the cavity. The sidewall of the annular forming mold core is arc-shaped and is used to press the glass to be processed to deform in the direction of the annular groove. The guide core is used to pass through the inner hole of the glass to be processed and then be inserted into the positioning groove. The temperature control component is embedded inside the lower mold base.

[0005] Furthermore, the hot bending mold also includes an infrared temperature measurement closed-loop feedback system, which is signal-connected to the temperature control component.

[0006] Furthermore, the infrared temperature measurement closed-loop feedback system includes multiple temperature measurement points, which are evenly arranged along the circumference of the annular groove.

[0007] Furthermore, the bottom of the guide core is provided with an exhaust groove.

[0008] Furthermore, the exhaust groove is arc-shaped.

[0009] Furthermore, the cavity of the lower mold base is provided with adsorption holes.

[0010] Furthermore, the surface of the annular molding core is provided with an anti-stick coating.

[0011] In a second aspect, the hot bending equipment provided by the present invention includes a lifting plate, an upper heating plate, a lower heating plate, a worktable, and a hot bending mold as described in any of the above claims; The lower mold base in the hot bending mold is installed on the support surface of the workbench, and the lifting plate is arranged opposite to the support surface of the workbench and can move towards or away from the support surface of the workbench. The lower heating plate is installed inside or below the workbench; The lower heating plate is installed on the lifting plate.

[0012] Thirdly, the forming method of the hot bending equipment provided by the present invention includes feeding; preheating; forming; annealing; and cooling.

[0013] Furthermore, the feeding includes: Place the glass to be processed on the lower mold base, insert the inner ring positioning core into the positioning groove after passing through the inner hole of the glass to be processed, and insert the auxiliary positioning insert between the side wall of the glass to be processed and the inner wall of the cavity. The upper frame mold is placed on the lower mold base and pressed down on the glass to be processed; Remove the inner ring positioning core; After the guide core passes through the inner hole of the glass to be processed, it is inserted into the positioning groove. The annular forming mold core is placed on the glass to be processed and pressed down in the direction of the annular groove.

[0014] Based on the above technical solutions, the technical effects achievable by this invention can be analyzed as follows: The hot bending mold provided by this invention includes a lower mold assembly, an upper mold assembly, and a temperature control assembly. The thermal expansion coefficients of the materials of the lower mold assembly and the upper mold assembly are greater than those of the glass to be processed. The lower mold assembly includes a lower mold base, a positioning core, and an auxiliary positioning insert. The cavity of the lower mold base is provided with a positioning groove and an annular groove, with the annular groove surrounding the outer periphery of the positioning groove. The positioning core is used to pass through the inner hole of the glass to be processed and then be inserted into the positioning groove. The auxiliary positioning insert is used to fit against the inner wall of the cavity and the outer wall of the glass to be processed. The upper mold assembly includes an upper frame mold, an annular forming mold core, and a guide core. The upper frame mold is used to press against the cavity-containing surface of the lower mold base. The sidewall of the annular forming mold core is arc-shaped and is used to press the glass to be processed to deform in the direction of the annular groove. The guide core is used to pass through the inner hole of the glass to be processed and then be inserted into the positioning groove. The temperature control assembly is embedded inside the lower mold base.

[0015] The hot bending mold adopts a vertical mold-closing structure consisting of an upper mold assembly and a lower mold assembly. The lower mold assembly serves as the foundation for mold forming and includes a lower mold base, a positioning core, and auxiliary positioning inserts, with a temperature control component embedded inside. An annular groove is formed in the center of the cavity of the lower mold base to match the annular forming core in the upper mold assembly, and a positioning groove is formed at the bottom to match the positioning core, ensuring precise fit. The positioning core, used in conjunction with the lower mold base, ensures accurate positioning of the central hole of the glass to be processed, preventing positioning deviations that could cause stress concentration, cracking, and edge chipping in the upper mold, and ensuring uniform heating and coordinated deformation of the annular ring. The auxiliary positioning insert assists in the placement of the glass to be processed, ensuring precise positioning of the unbent portion. The upper mold assembly is a key part of mold forming, including the upper frame mold, the annular forming mold core, and the guide core. The upper frame mold is aligned with the planar area of ​​the glass to be processed, avoiding irreversible deformation caused by the annular area pulling on the planar area during the forming process, and achieving uniform pressing of the glass surface. The sidewalls of the annular forming mold core are curved to adapt to the curvature radius of the round hole glass during hot bending, and can be replaced according to different curvature requirements. The lower surface of the annular forming mold core precisely matches the round hole of the glass to be processed. The guide core matches the annular forming mold core for precise vertical mold closing.

[0016] When using this hot bending die, the glass to be processed is first placed on the lower die base. The movable auxiliary positioning inserts and positioning cores are used to position the flat area of ​​the glass. Utilizing the precise structure with a clearance of ≤0.01mm between the inserts and the lower die base, the center hole and the placement position of the glass are simultaneously positioned, avoiding positioning deviations. The upper frame die is then pressed down to lightly press the flat area of ​​the glass, with the pressure controlled at 0.05~0.1MPa. The positioning core is then removed to prevent the glass from being crushed during subsequent pressing. Simultaneously, the upper frame die continuously applies pressure to the non-forming area, ensuring the flatness of that area. The guide core and the annular forming die core are then placed sequentially. The guide core and the annular forming die core precisely match to achieve vertical guidance. The curved surface of the annular forming die core precisely fits the center hole of the glass, completing the placement process.

[0017] The temperature control component is embedded inside the lower mold base to ensure precise and controllable temperature.

[0018] This hot bending die is a special hot bending die adapted for the forming of annular glass. By optimizing the thermal conductivity of the die material and the distribution of structural thermal resistance, the uniformity of the circumferential temperature field is controlled within ±5℃, while reducing the risk of local stress concentration during the hot bending process.

[0019] Compared with traditional general-purpose hot bending dies, this hot bending die achieves comprehensive improvements in yield, precision, and service life: It adapts to the thermophysical properties of glass and solves problems such as cracking, edge chipping, and die marks during the hot bending process through partitioned pressing, increasing the yield of finished products for hot bending glass circular holes into rings to over 95%, and ensuring the optical properties of the glass surface meet high-precision requirements; the precise positioning structure effectively improves the dimensional accuracy and roundness consistency of the ring-shaped 3D glass, with forming tolerances far exceeding industry standards, eliminating the need for subsequent secondary correction processing and reducing process material consumption and processing costs; the heat-resistant and wear-resistant die body design and embedded temperature control components enhance the high-temperature stability and service life of the die, reducing the frequency of die maintenance and replacement, and significantly lowering overall production costs; the modular assembly structure enables the adaptation and processing of multiple glass specifications, improving the versatility and production efficiency of the die, filling the technological gap in the industry for dedicated dies for hot bending glass circular holes into rings, and providing reliable processing equipment support for applications in the field of ring-shaped structural components. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments of this application will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 An isometric view of the hot bending die provided in an embodiment of this application; Figure 2 This is a front view schematic diagram of the hot bending die provided in the embodiments of this application; Figure 3 A schematic diagram of the lower die base in the hot bending die provided in the embodiments of this application; Figure 4 A top view of the lower die base in the hot bending die provided in the embodiments of this application; Figure 5 This is an isometric view of the positioning core in the hot bending mold provided in an embodiment of this application (without the glass to be processed placed on it). Figure 6 An isometric view of the positioning core in the hot bending mold provided in this application embodiment (with the glass to be processed placed there). Figure 7 This is an isometric view of the upper frame mold pressing the glass to be processed in the hot bending mold provided in the embodiment of this application; Figure 8 An isometric view of the guide core in a hot bending die provided in an embodiment of this application; Figure 9 This is an isometric view of the placement of the annular forming core in the hot bending die provided in the embodiment of this application; Figure 10 This is an isometric view of the annular forming core in the hot bending mold provided in the embodiments of this application after forming; Figure 11 This is a schematic diagram of the temperature control component in the hot bending mold provided in the embodiments of this application.

[0022] icon: 1-Guide core; 2-Ring forming mold core; 3-Upper frame mold; 4-Glass to be processed; 5-Ring 3D glass; 6-Lower mold base; 7-Auxiliary positioning insert; 8-Positioning core; 9-Temperature control component. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0024] In the description of this application, it should be noted that the terms "inner" and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product is in use. They are used only for the convenience of describing this application and for 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. Furthermore, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0025] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "setup" and "connection" 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 direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0026] Example 1 Currently, the mold design for hot bending glass with round holes into ring structures is not yet perfect in glass hot bending technology. Existing molds are mostly general-purpose structures, not specifically adapted to the thermophysical properties of glass and the required forming precision, resulting in numerous technical defects: the uniformity deviation of the circumferential temperature field during forming can reach ±18℃ or more, and the internal stress concentration in the glass can exceed 85MPa, making it highly susceptible to cracking, edge chipping, and mold marks. Furthermore, the compressive stress concentration caused by positioning deviations further exacerbates product defects, ultimately resulting in an extremely low yield rate for hot bending round holes into rings (average ≤60% across all specifications), far lower than the basic yield rate of 80% for ordinary glass hot bending. The forming core of general-purpose molds is a fixed structure, and after forming, the 3D ring glass has a roundness tolerance ≥±1.2mm and a surface roughness Ra≥1.5μm, requiring subsequent secondary correction processing, increasing process material consumption and processing costs.

[0027] In view of this, see Figures 1 to 11 The hot bending mold provided in this embodiment of the invention includes a lower mold assembly, an upper mold assembly, and a temperature control assembly 9. The thermal expansion coefficients of the materials of the lower mold assembly and the upper mold assembly are greater than the thermal expansion coefficient of the glass 4 to be processed. The lower mold assembly includes a lower mold base 6, a positioning core 8, and an auxiliary positioning insert 7. The cavity of the lower mold base 6 is provided with a positioning groove and an annular groove, with the annular groove surrounding the outer periphery of the positioning groove. The positioning core 8 is used to pass through the inner hole of the glass 4 to be processed and then inserted into the positioning groove. The auxiliary positioning insert 7 is used to fit against the inner wall of the cavity and the outer wall of the glass 4 to be processed. The upper mold assembly includes an upper frame mold 3, an annular forming mold core 2, and a guide core 1. The upper frame mold 3 is used to press against the surface of the lower mold base 6 with a cavity. The side wall of the annular forming mold core 2 is arc-shaped and is used to press the glass 4 to be processed to deform in the direction of the annular groove. The guide core 1 is used to pass through the inner hole of the glass 4 to be processed and then inserted into the positioning groove. The temperature control assembly 9 is embedded inside the lower mold base 6.

[0028] Specifically, multiple auxiliary positioning inserts 7 are provided, and the multiple auxiliary positioning inserts 7 are spaced apart along the circumference of the lower mold base 6.

[0029] The hot bending mold adopts a vertical mold-closing structure of upper and lower mold components. The lower mold component serves as the foundation for mold forming and includes a lower mold base 6, a positioning core 8, and an auxiliary positioning insert 7, with a temperature control component 9 embedded inside. An annular groove is formed in the center of the cavity of the lower mold base 6 to match the annular forming core 2 in the upper mold component, and a positioning groove is formed at the bottom to match the positioning core 8, ensuring precise fit. The positioning core 8 is used in conjunction with the lower mold base 6 to ensure precise positioning of the central hole of the glass 4 to be processed, preventing positioning deviations from causing stress concentration and cracking of the upper mold, and ensuring uniform heating and coordinated deformation of the ring. The auxiliary positioning insert 7 assists in the placement of the glass 4 to be processed, ensuring precise positioning of the unbent portion. The upper mold assembly is a key part of mold forming, including the upper frame mold 3, the annular forming mold core 2, and the guide core 1. The upper frame mold is consistent with the plane area of ​​the glass to be processed 4, which avoids irreversible deformation caused by the annular area pulling the plane area during the forming process, and achieves uniform pressing of the glass surface. The side wall of the annular forming mold core 2 is arc-shaped, which is adapted to the curvature radius of the round hole glass hot bending and can be replaced according to different curvature requirements. The lower surface of the annular forming mold core 2 is precisely matched with the round hole of the glass to be processed 4. The guide core 1 matches the annular forming mold core 2 for precise vertical mold closing.

[0030] When using this hot bending die, the glass to be processed 4 is first placed on the lower die base 6. The movable auxiliary positioning insert 7 and positioning core 8 are used to position the flat area of ​​the glass to be processed 4. Utilizing the precise structure with a fit clearance of ≤0.01mm between the two and the lower die base 6, the center hole and the placement position of the glass to be processed 4 are simultaneously positioned to avoid positioning deviation. The upper frame die 3 is then pressed down to lightly press the flat area of ​​the glass to be processed 4. The light pressure value is controlled at 0.05~0.1MPa. Then, the positioning core 8 is removed to prevent the glass to be processed 4 from being crushed during subsequent pressing. At the same time, the upper frame die 3 continuously applies pressure to the non-forming area to ensure the flatness of this area. The guide core 1 and the annular forming die core 2 are then placed in sequence. The guide core 1 and the annular forming die core 2 precisely cooperate to achieve vertical guidance. The arc surface of the annular forming die core 2 precisely fits the round hole of the glass to be processed 4, completing the placement.

[0031] The temperature control component 9 is embedded inside the lower mold base 6 to ensure precise and controllable temperature.

[0032] This hot bending die is a special hot bending die adapted for the forming of annular glass. By optimizing the thermal conductivity of the die material and the distribution of structural thermal resistance, the uniformity of the circumferential temperature field is controlled within ±5℃, while reducing the risk of local stress concentration during the hot bending process.

[0033] Compared with traditional general-purpose hot bending dies, this hot bending die achieves comprehensive improvements in yield, precision, and service life: It adapts to the thermophysical properties of glass and solves problems such as cracking, edge chipping, and die marks during the hot bending process through partitioned pressing, increasing the yield of finished products with round glass holes bent into rings to over 95%, and ensuring the optical properties of the glass surface meet high-precision requirements; the precise positioning structure effectively improves the dimensional accuracy and roundness consistency of the 3D ring glass 5, with forming tolerances far exceeding industry standards, eliminating the need for subsequent secondary correction processing and reducing process material consumption and processing costs; the heat-resistant and wear-resistant die body design and embedded temperature control component 9 enhance the high-temperature stability and service life of the die, reducing the frequency of die maintenance and replacement, and significantly lowering overall production costs; the modular assembly structure enables the adaptation and processing of multiple glass specifications, improving the versatility and production efficiency of the die, filling the technological gap in the industry for dedicated dies for hot bending round glass holes into rings, and providing reliable processing equipment support for applications in the field of ring structure components.

[0034] The structure of the hot bending die is described in detail below: In the optional solution provided by the embodiments of the present invention, the hot bending mold further includes an infrared temperature measurement closed-loop feedback system, which is signal-connected to the temperature control component 9.

[0035] Specifically, the temperature control component 9 includes a temperature control pipeline embedded in a pre-set hole in the mold core of the lower mold base 6 channel. The pipeline connects to a sensor circuit to the temperature controller. The temperature control pipeline is made of copper with a diameter of 3-5 mm and a spacing of 10-15 mm within the mold core. The sensor is a type K thermocouple with a temperature measurement accuracy of ±1℃. Alternatively, a thin-film thermocouple can be used, with a temperature measurement accuracy of ±0.3℃. This improves the temperature control response speed by 0%. Combined with an infrared temperature measurement closed-loop feedback system, it can achieve circumferential temperature field uniformity control within ±1℃. Simultaneously, an external cooling air duct can be added, evenly distributed along the mold circumference, to achieve forced temperature control during the annealing stage. The cooling rate adjustment range is extended to 3~15℃ / min, adapting to the annealing requirements of different glasses.

[0036] The hot bending mold adopts a split heating structure, combined with an infrared temperature measurement closed-loop feedback system, to dynamically adjust the heating power of each area, ensuring that the glass is heated evenly near the softening point and the deformation is coordinated, thereby improving the geometric accuracy and structural integrity during the transformation from a circular hole to a ring.

[0037] In the optional solution provided by the embodiments of the present invention, the infrared temperature measurement closed-loop feedback system includes multiple temperature measurement points, which are evenly arranged along the circumference of the annular groove.

[0038] Specifically, the infrared temperature measurement closed-loop feedback system is connected to both the upper and lower heating plates of the hot bending equipment. The temperature measurement points are evenly distributed along the circumference of the glass ring area, with a quantity of 12 to 24 points. The temperature measurement response time is ≤0.5s, the heating power adjustment step is 50W, and the adjustment range is 500 to 3000W. This system is used to dynamically adjust the heating power of each area, so that the uniformity of the circumferential temperature field is controlled within ±5℃.

[0039] In the optional solution provided in the embodiments of the present invention, the bottom of the guide core 1 is provided with an exhaust groove.

[0040] Specifically, the guide core 1 is configured as a cylindrical structure to precisely and vertically close with the annular forming mold core 2. The bottom of the guide core 1 is provided with venting grooves, which are arc-shaped, 0.5~1.0mm wide, and 0.3~0.5mm deep. Preferably, multiple venting grooves are provided, evenly arranged along the circumference of the guide core 1, with a quantity of 8~16 grooves.

[0041] Venting grooves are used to reduce the gas resistance inside the mold during the mold closing process.

[0042] In the optional solution provided in the embodiments of the present invention, the cavity of the lower mold base 6 is provided with adsorption holes.

[0043] Specifically, adsorption holes are opened in the cavity of the lower mold base 6. The adsorption holes are evenly distributed along the circumference of the glass plane area, and the adsorption vacuum degree is -0.06~-0.08MPa. The adsorption holes realize non-contact positioning of the glass 4 to be processed, avoiding scratches on the glass surface caused by mechanical positioning. The surface scratch rate is reduced to ≤0.1%, which is suitable for processing circular 3D glass 5 with high optical requirements.

[0044] In the optional solution provided in the embodiments of the present invention, the surface of the annular molding core 2 is provided with an anti-stick coating.

[0045] Specifically, the annular forming mold core 2 is a replaceable integrated arc-shaped hollow structure, which is adapted to the curvature radius of round hole glass hot bending (R=25~100mm, which can be replaced according to different curvature requirements. The fit gap between the replaced annular forming mold core 2 and the upper frame mold 3 and guide core 1 is ≤0.01mm). The inner ring diameter of the annular forming mold core 2 is φ48~φ198mm, the arc surface curvature is 90° (adapted to 90° circular ring hot bending), and the arc height H<200mm. The lower surface of the annular forming mold core 2 is precisely matched with the round hole of the glass 4 to be processed. The arc surface is mirror polished with a polishing accuracy Ra≤0.1μm, and the surface is coated with a polytetrafluoroethylene anti-stick layer with a thickness of 0.05~0.1mm to prevent mold imprint residue. Alternatively, the annular molding core 2 can be configured as an annular airbag-type flexible pressing structure. The airbag is made of high-temperature resistant fluororubber with a temperature resistance of ≤800℃. The airbag inflation pressure range is 0.03~0.08MPa. The contact method between the airbag and the glass is full circumferential bonding. The airbag is fixed to the outside of the guide core 1 of the upper mold assembly. The flexible pressing structure realizes uniform pressing of the glass in the full circumference, and the pressing pressure is more precise, effectively avoiding local stress concentration. The glass cracking rate can be reduced to ≤0.3%, which is suitable for processing thin-walled (thickness ≤1.5mm) annular 3D glass 5.

[0046] In the optional embodiment of this invention, the lower mold base 6 is generally rectangular in structure, with an annular groove at the center of the cavity. The groove width matches the annular forming mold core 2, with a gap ≤0.01mm, and the groove depth is 52mm. A positioning groove for the matching positioning core 8 is also provided to ensure precise fit. Furthermore, the rectangular corners of the lower mold base 6 are rounded with a radius of 5-8mm. It is connected to the worktable of the hot bending equipment by bolt fixing, with fixing holes evenly distributed around the lower mold base 6. The positioning core 8 is used in conjunction with the lower mold base 6, with a gap ≤0.01mm.

[0047] In the optional solution provided in the embodiments of the present invention, the light pressure value of the upper frame mold 3 on the glass 4 to be processed is set to 0.05-0.1MPa.

[0048] In the optional embodiment of the present invention, the upper mold assembly and the lower mold assembly are made of EDM-200 isotropic ultrafine graphite particles with an average particle size of <10μm, a hardness of HRC68, a high temperature resistance of ≤1200℃, and a coefficient of thermal expansion of 9.6×10⁻⁶. -6 / ℃~9.8×10 -6 / ℃ (≥ coefficient of thermal expansion of glass), thermal conductivity (700℃) W / (m·K): 100~180, high temperature deformation ≤0.02mm / 100h; surface plated with chromium nitride (CrN) for wear resistance and impact resistance, improving mold life. Of course, depending on the different properties of the glass to be processed (soda-lime glass, borosilicate glass, quartz glass), different materials can be used. For metals / alloys, Inconel 718 high-temperature alloy (high temperature resistance ≥1100℃, coefficient of thermal expansion 12.8×10⁻⁶) is an option. -6 / ℃, suitable for high expansion coefficient soda-lime glass), ceramic options include alumina ceramic (high temperature resistance ≥1600℃, thermal expansion coefficient 7.6×10), -6 / ℃, suitable for low expansion coefficient quartz glass); after material replacement, the preheating temperature of the molding process is adjusted by ±20℃ and the molding temperature is adjusted by ±30℃ to ensure matching with the thermophysical properties of the glass.

[0049] In the optional solutions provided by the embodiments of the present invention, the lower mold base 6, the annular forming mold core 2, and the auxiliary positioning insert 7 are separate structures. Of course, the solution of integrating the lower mold base 6, the annular forming mold core 2, and the auxiliary positioning insert 7 into one piece is also within the protection scope of the embodiments of the present invention. The mold body is integrally machined with a precision machining process to form the forming arc surface, the positioning and limiting groove, and the embedded temperature control channel. The concentricity tolerance between the forming arc surface and the positioning and limiting groove is ≤0.005mm. The integrated structure reduces the assembly gap, further improves the positioning accuracy, optimizes the roundness tolerance to ≤±0.3mm, and improves the mold changing efficiency by 40%, which is suitable for mass production of single-specification glass.

[0050] This hot bending mold solves core technical problems in the industry, such as cracking and chipping of glass circular holes during hot bending, mold marks, positioning deviations, low yield, and lack of dedicated molds. Through dedicated mold structure design and optimized forming process, it achieves a finished product yield of ≥95%, roundness tolerance of ≤±0.5mm, and Ra≤0.8μm, and is suitable for processing glass with multiple specifications of circular holes from φ50mm to φ200mm.

[0051] Compared to existing general-purpose molds and traditional processes, this hot bending mold features material selection adapted to the thermophysical properties of glass and an anti-stick mold surface design. Combined with a zoned pressing and precise positioning structure, it completely solves the problems of cracking, edge chipping, and mold marks during the hot bending process, increasing the finished product yield to 95%. The above-mentioned glass surface optical properties meet the requirements for high-precision use, and the occurrence rate of abnormalities is reduced to less than 2%. The combination of the integrated arc-shaped hollow forming mold core and the infrared temperature measurement closed-loop feedback system effectively improves the dimensional accuracy and roundness consistency of the circular 3D glass 5. The forming tolerance is far superior to the industry standard, eliminating the need for subsequent secondary correction processing and reducing process material consumption and processing costs by more than 30%. The heat-resistant and wear-resistant mold body design and the embedded temperature control component 9 improve the high-temperature stability and service life of the mold, continuously processing ≥50,000 qualified products, reducing the frequency of mold maintenance and replacement, and significantly reducing the overall production cost. The modular assembly structure and replaceable forming mold core enable the adaptation and processing of multiple specifications of glass, making mold changing convenient and reducing the processing time of a single product by ≥33.3%. This improves the versatility and production efficiency of the mold, fills the technical gap in the industry of lacking a dedicated mold for hot bending glass circular holes into circular rings, and provides reliable processing equipment support for the application of circular structure parts. The segmented temperature, pressure, and time precise control of the forming process effectively reduces the internal stress of the glass to below 20MPa, improving the structural integrity and reliability of the product.

[0052] Example 2 The hot bending equipment provided in this embodiment of the invention includes the hot bending mold described in Embodiment 1, and therefore also possesses all the beneficial effects of Embodiment 1, which will not be repeated here.

[0053] In the optional solution provided by the embodiments of the present invention, the hot bending equipment includes a lifting plate, an upper heating plate, a lower heating plate and a worktable; the lower mold base 6 in the hot bending mold is installed on the support surface of the worktable, the lifting plate is arranged opposite to the support surface of the worktable and can move towards or away from the support surface of the worktable; the lower heating plate is installed inside or below the worktable; the lower heating plate is installed on the lifting plate.

[0054] Specifically, this hot bending mold is a vertical mold-closing structure consisting of an upper mold assembly and a lower mold assembly, compatible with hot bending equipment such as Han's Laser-18 / 28 station, EAGLE 3D, and Landi LD-EJ / Lever LV-TB. It can process round-hole glass with specifications ranging from φ50mm to φ200mm. After forming, the roundness tolerance of the circular 3D glass is ≤±0.5mm, and the surface roughness Ra is ≤0.8μm. The upper and lower heating plates use non-contact heat radiation heating, or microwave heating with a microwave frequency of 2450MHz. By selectively heating the glass with microwaves, the heating efficiency is improved by 50%, and the total time for preheating and forming stages is reduced by ≥40%. Furthermore, microwave heating ensures uniform heating inside the glass, further reducing internal stress, making it suitable for high-efficiency production scenarios.

[0055] The upper heating plate and the lower heating plate are used to preheat and heat the glass 4 to be processed in the hot bending mold, so that it can be deformed and hot bent.

[0056] Example 3 The forming method of the hot bending equipment described in the second application embodiment of the present invention includes the following steps: feeding; preheating; forming; annealing; and cooling.

[0057] The hot bending die is compatible with the Huanqiu 10040H hot bending equipment to process aluminosilicate round-hole glass with a diameter of φ50mm~φ200mm and a thickness of 1.3mm. The specific implementation steps are as follows: Material feeding stage: Place the glass to be processed 4 on the lower mold base 6, insert the inner ring positioning core 8 into the positioning groove after passing through the inner hole of the glass to be processed 4, and insert the auxiliary positioning insert 7 between the side wall of the glass to be processed 4 and the inner wall of the cavity; place the upper frame mold 3 on the lower mold base 6 and press down on the glass to be processed 4; remove the inner ring positioning core 8; insert the guide core 1 into the positioning groove after passing through the inner hole of the glass to be processed 4, and place the annular forming mold core 2 on the glass to be processed 4 and press down in the direction of the annular groove.

[0058] The glass to be processed 4 is placed on the lower mold base 6. The movable auxiliary positioning insert 7 and positioning core 8 are used to position the flat area of ​​the glass to be processed 4. Utilizing the precise structure with a fit clearance of ≤0.01mm between the two and the lower mold base 6, the center hole and the material placement position of the glass to be processed 4 are dually positioned to avoid positioning deviation. The upper frame mold 3 is pressed down to apply light pressure to the flat area of ​​the glass to be processed 4. The light pressure value is controlled at 0.05~0.1MPa. Then the positioning core 8 is removed to prevent the glass to be processed 4 from being crushed during subsequent pressing. At the same time, the upper frame mold 3 continuously applies pressure to the non-forming area to ensure the flatness of this area.

[0059] See Figure 8 and Figure 9The guide core 1 and the annular forming mold core 2 are placed in sequence. The guide core 1 and the annular forming mold core 2 are precisely matched to achieve vertical guidance. The venting groove at the bottom of the guide core 1 effectively reduces the gas resistance when the mold is closed. The arc surface of the annular forming mold core 2 is precisely fitted with the round hole of the glass to be processed 4 to complete the material feeding.

[0060] Preheating stage: Start the upper and lower heating plates of the hot bending equipment, and in conjunction with the embedded temperature control component 9 and the infrared temperature measurement closed-loop feedback system, heat the mold and glass to keep the preheating temperature stable at 570-610℃ for 5-8 minutes. This ensures that the glass in this area is in a relatively hard state, while keeping the temperature difference between the glass annular area and the planar area within a small range to avoid excessive internal stress and cracking of the glass. It also allows the glass to reach a certain degree of softening to prepare for subsequent forming.

[0061] Forming Stage: Through precise control using an infrared temperature measurement closed-loop feedback system, the glass annular area is heated non-contactly by heat radiation from the upper and lower heating plates, maintaining the temperature of this area stably at 680-720℃ for 3-5 minutes. During this stage, the glass is only subjected to the self-weight pressure of the upper frame mold 3 and the annular forming mold core 2. The annular forming mold core 2 is guided by the guide core 1 to achieve vertical and slow downward pressure at a speed of 0.5-1.0 mm / min, so that the semi-formed glass completely fits the arc surface of the annular forming mold core 2. The upper frame mold 3 always keeps the glass flat area pressed to avoid the flat area being stretched and twisted or deformed, ensuring that the product is completely formed and fits the mold. During the forming process, the uniformity of the circumferential temperature field is controlled within ±2.5℃.

[0062] Annealing stage: After the glass is formed into a circular 3D glass ring 5, the upper and lower heating plates are pressed down and the temperature is adjusted to 520-580℃. The mold holds the glass under pressure of 0.1~0.2MPa and slowly cools it down at a rate of 5~10℃ / min. The total annealing time is 8~12min, which effectively releases the internal stress of the glass and reduces the risk of cracking.

[0063] Cooling stage: Turn off the heating function of the upper and lower heating plates, and continue to hold the glass under pressure in the mold until the glass temperature drops below 200℃. Then release the pressure and let the glass continue to cool naturally in the mold to room temperature. The entire cooling process takes 15~20 minutes. Since the thermal expansion coefficient of the core material of the mold is greater than or equal to that of the glass, the shrinkage ratio is large. During the cooling process, the glass and the mold shrink synchronously, which makes it less likely to crack or chip. Finally, the glass is removed to obtain the finished 3D ring glass.

[0064] The 3D circular glass rings processed using this molding method have a yield rate of ≥97.5% for φ50mm, ≥96.8% for φ100mm, ≥96.0% for φ150mm, and ≥95.2% for φ200mm. The average roundness tolerance of all specifications is ≤±0.35mm, the surface roughness Ra is ≤0.6μm, and the internal stress of the glass is ≤20MPa, which fully meets the requirements for high-precision use.

[0065] It should be noted that, where there is no conflict, the features in the embodiments of this application can be combined with each other.

[0066] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A hot bending die, characterized in that, include: Lower mold assembly, upper mold assembly and temperature control assembly (9); The coefficient of thermal expansion of the materials of the lower mold assembly and the upper mold assembly is greater than that of the glass to be processed (4); The lower mold assembly includes a lower mold base (6), a positioning core (8), and an auxiliary positioning insert (7). The cavity of the lower mold base (6) is provided with a positioning groove and an annular groove, and the annular groove surrounds the outer periphery of the positioning groove. The positioning core (8) is used to pass through the inner hole of the glass to be processed (4) and then be inserted into the positioning groove. The auxiliary positioning insert (7) is used to fit against the inner wall of the cavity and the outer wall of the glass to be processed (4). The upper mold assembly includes an upper frame mold (3), an annular forming mold core (2), and a guide core (1). The upper frame mold (3) is used to press against the surface of the lower mold base (6) having the cavity. The sidewall of the annular forming mold core (2) is arc-shaped and is used to press the glass to be processed (4) to deform in the direction of the annular groove. The guide core (1) is used to pass through the inner hole of the glass to be processed (4) and then be inserted into the positioning groove. The temperature control component (9) is embedded inside the lower mold base (6).

2. The hot bending die according to claim 1, characterized in that, The hot bending mold also includes an infrared temperature measurement closed-loop feedback system, which is signal-connected to the temperature control component (9).

3. The hot bending die according to claim 2, characterized in that, The infrared temperature measurement closed-loop feedback system includes multiple temperature measurement points, which are evenly arranged along the circumference of the annular groove.

4. The hot bending die according to claim 1, characterized in that, The bottom of the guide core (1) is provided with an exhaust groove.

5. The hot bending die according to claim 4, characterized in that, The exhaust channel is arc-shaped.

6. The hot bending die according to claim 1, characterized in that, The cavity of the lower mold base (6) is provided with adsorption holes.

7. The hot bending die according to claim 1, characterized in that, The surface of the annular molding core (2) is provided with an anti-stick coating.

8. A hot bending device, characterized in that, It includes a lifting plate, an upper heating plate, a lower heating plate, a worktable, and a hot bending die as described in any one of claims 1-7; The lower mold base (6) in the hot bending mold is installed on the support surface of the workbench. The lifting plate is arranged opposite to the support surface of the workbench and can move towards or away from the support surface of the workbench. The lower heating plate is installed inside or below the workbench; The lower heating plate is installed on the lifting plate.

9. A forming method using the hot bending equipment as described in claim 8, characterized in that, include: Feeding; preheating; molding; annealing; cooling.

10. The method according to claim 9, characterized in that, The feeding process includes: Place the glass to be processed (4) on the lower mold base (6), insert the inner ring positioning core (8) through the inner hole of the glass to be processed (4) into the positioning groove, and insert the auxiliary positioning insert (7) between the side wall of the glass to be processed (4) and the inner wall of the cavity. The upper frame mold (3) is placed on the lower mold base (6) to press down the glass (4) to be processed; Remove the inner ring positioning core (8); The guide core (1) is inserted into the positioning groove after passing through the inner hole of the glass to be processed (4). The annular forming core (2) is placed on the glass to be processed (4) and pressed down in the direction of the annular groove.

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