A method and mold for layered array molding process

Abstract

This invention discloses a layered array molding process and mold. The process constructs a multi-layered array mold cavity by stacking a lower mold, an intermediate mold, and a stepped upper mold within a sleeve, and placing a convex spherical top plate on the top of the upper mold to form point contact stress transmission. The process flow includes four stages: heating and holding, high-temperature molding, depressurization annealing, and cooling and demolding. The intermediate mold serves as the pressure load medium, enabling the simultaneous forming of double-layer lenses within a single molding stroke. Simultaneously, a physical reset mechanism formed by the guide cone surface at the sleeve inlet and the rounded corner at the bottom of the upper mold solves the problem of reset jamming caused by cumulative thermal expansion in multi-layered components. This invention significantly improves the processing efficiency and forming fidelity of glass molding.

Description

Technical Field

[0001] This invention relates to the field of optical glass molding, specifically to a stacked array molding process (SAM) molding method and mold. Background Technology

[0002] With the rapid development of photoelectric detection and imaging technology, glass lenses are increasingly widely used in fields such as security monitoring, vehicle infrared assisted driving, and smart terminals. Achieving large-scale, high-precision production of such glass optical components has become a key industry priority.

[0003] Current mainstream strategies for improving glass molding efficiency, such as multi-station and wafer-level molding, while showing significant advantages in mass production, still face common challenges such as complex equipment structures, high costs, and uneven filling due to temperature fluctuations. Although they increase output per unit time, space utilization is still limited by the machine's pressure area. In the pursuit of higher output in double-layer molding, the increased number of mold components leads to a surge in cumulative thermal expansion displacement, easily causing eccentric stress and reset jamming. Existing processes lack a solution that can simultaneously achieve both multi-layer forming efficiency and precise automatic correction. Summary of the Invention

[0004] The purpose of this invention is to provide a stacked array molding process (SAM) forming method and mold structure, so as to achieve a significant increase in production efficiency while ensuring long mold life through automatic correction logic.

[0005] The technical solution to achieve the purpose of this invention is as follows:

[0006] A stacked arrayed compression molding die includes: a lower die, an intermediate die, a sleeve, an upper die, and a convex ball top plate;

[0007] The sleeve is disposed on the upper side of the lower mold; at least one intermediate mold is provided inside the sleeve, which is used to divide the inner cavity of the sleeve into multiple mold cavities and conduct heat to the mold cavities above and below it; the mold cavity is used to place the glass preform, and the sleeve is provided with a sleeve exhaust hole at the position corresponding to the mold cavity, which is connected to an external vacuum auxiliary system;

[0008] The upper inner wall of the sleeve is provided with a guide cone surface; the lower end of the upper mold is provided with a guide section that fits with the sleeve clearance, the lower end of the guide section is provided with a relief fillet that fits with the guide cone surface, and the top is provided with a concave ball seat; the bottom surface of the convex ball top plate is provided with a convex ball surface that fits with the concave ball seat, so that the convex ball top plate and the upper mold form a point contact when they are in axial contact.

[0009] The lower mold, upper mold, and intermediate mold are respectively provided with arrayed structural cavities on their upper and lower forming surfaces, and each arrayed cavity corresponds to the other along the mold axis.

[0010] A layered array molding method includes:

[0011] S1. After sequentially inserting the lower mold and the first layer of glass preform, install the sleeve. Inside the sleeve, arrange the intermediate thin mold and other layers of glass preform and the stepped upper mold from bottom to top to construct the stacked space in sequence.

[0012] S2. Stack a convex ball top plate with a convex spherical surface on the concave ball seat at the top of the upper mold, and use the ball head point contact to align the pressure load to the center of the mold axis.

[0013] S3. Place the mold in the vacuum chamber of the single-station molding press, evacuate the vacuum, and introduce protective gas.

[0014] S4. Control the molding environment to heat up to the specified temperature range, enter the heating and heat preservation stage to make the multilayer glass soften evenly. During the period when the mold floats and shifts upward due to the cumulative thermal expansion, the guide cone surface of the sleeve inlet physically envelops the avoidance rounded corners of the bottom of the stepped upper mold.

[0015] S5. Entering the molding stage, during the downward molding stroke of the press, the guide cone and the avoidance fillet work together to force correction and guide the mold back to its position; then the pressure is transmitted downward through the convex ball top plate to transmit the pressure load, and the synchronous filling and forming of the multi-layer lens is achieved through the load relay effect of the intermediate mold.

[0016] S6. Annealing and Cooling Demolding: After forming, depressurization annealing is performed to release internal stress. After cooling, the upper mold returns to the starting position to complete demolding.

[0017] The significant advantages of this invention compared to existing technologies are:

[0018] (1) This invention provides a stacked array molding one-time molding method and system. By introducing an intermediate thin mold to construct a vertical stacked mold cavity, and with array arrangement, the single molding stroke is doubled based on simple equipment, which significantly improves the processing efficiency of glass molding and reduces energy consumption costs.

[0019] (2) The present invention uses the point contact stacking structure of the convex ball top plate and the stepped upper mold to force the pressure load to be aligned to the center of the mold shaft by using mechanical decoupling logic, which effectively eliminates the eccentric torque caused by the non-parallelism of the press plate and avoids mold displacement caused by uneven force under multi-layer molding conditions.

[0020] (3) The present invention utilizes the micro-stroke capture logic formed by the guide cone surface of the sleeve inlet and the avoidance rounded corner of the bottom of the upper mold to solve the problem of reset jamming caused by excessive cumulative displacement of the mold components during the process of glass softening at high temperature and thermal expansion, ensuring the stable operation of the molding cycle and greatly extending the service life of the mold. Attached Figure Description

[0021] Figure 1 This is a three-dimensional outline view of the stacked array molding system structure of the present invention;

[0022] Figure 2 This is an overall assembly cross-sectional view of the stacked array molding system structure of the present invention;

[0023] Figure 3 This is a partially enlarged schematic diagram showing the fit between the bottom rounded corner of the stepped upper mold and the guide cone surface of the sleeve.

[0024] Figure 4 A schematic diagram of the force analysis of a convex spherical plate and a stepped upper mold in point contact layered structure;

[0025] Figure 5 This is a planar view of the arrayed cavities of the mold.

[0026] Figure 6 This is a schematic diagram of the layered array molding process of the present invention.

[0027] In the attached drawings, the reference numerals are as follows: 1-stepped lower mold, 2-glass, 3-intermediate mold, 4-sleeve, 41-guide cone, 42-vent hole, 5-stepped upper mold, 51-concave ball seat, 52-rounded corner, 6-top plate, 61-convex spherical surface. Detailed Implementation

[0028] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0029] This embodiment of a stacked arrayed molding die includes a stepped lower die 1, an intermediate die 3, a sleeve 4, a stepped upper die 5, and a convex spherical top plate 6. The stepped lower die 1 has a stepped boss at its upper end for fitting the sleeve 4 and supporting the glass. The stepped lower die 1, the stepped upper die 5, and the intermediate die 3 are respectively provided with arrayed structural cavities on their upper and lower forming surfaces, and each layer of arrayed cavities corresponds to the other along the die axis. The sleeve 4 is fitted onto the outside of the stepped lower die 1, the intermediate die 3, and the stepped upper die 5, and the upper inner wall of the sleeve 4 is machined with an inwardly converging guide cone surface 41. The stepped upper die 5 has a precision guide section at its lower end that fits with the sleeve clearance, and the bottom edge of this section is machined with a relief fillet 52 that fits with the guide cone surface 41. The stepped upper die 5 has a concave spherical seat 51 at its top. The bottom surface of the convex spherical top plate 6 is machined with a convex spherical surface 61 that fits with the concave spherical seat 51.

[0030] Combination Figure 5 The arrayed structural cavities are arranged regularly and equidistantly in the corresponding plane, and non-forming functional areas are provided between adjacent cavities to isolate the flow interference of glass during the high-temperature molding process.

[0031] The outer end surfaces of the stepped lower mold 1, intermediate mold 3, and stepped upper mold 5 located inside the sleeve 4 are all high-precision machined surfaces with a surface roughness of no more than 10 nm, and the outer diameter and the inner diameter of the sleeve 4 are in clearance fit.

[0032] The radius of curvature R1 of the convex spherical surface 61 is smaller than the radius of curvature R2 of the concave spherical seat 51, so that the two form a point contact structure when they are in axial contact, and a floating gap is formed in the radial direction to allow the mold assembly to absorb thermal expansion displacement.

[0033] The sleeve 4 has exhaust holes 42 on the side wall at the height of the corresponding arrayed mold cavity, and is connected to an external vacuum auxiliary system to discharge the gas in the mold cavity.

[0034] In this embodiment, the arrayed cavity structure uses individual optical lens cavities as basic units, arranged regularly along the radial and circumferential directions on the mold forming surface to form a two-dimensional planar array. Each arrayed cavity corresponds one-to-one along the mold axis in the stepped lower mold 1, intermediate mold 3, and stepped upper mold 5, enabling the upper and lower glass layers to complete synchronous array forming within the same molding stroke. Combined with... Figure 6 Specifically, it includes the following process stages:

[0035] In the initial heating and heat preservation stage, the mold is assembled with the sleeve 4 in the following order: stepped lower mold 1, first layer glass preform 2, intermediate mold 3, second layer glass preform 2, and stepped upper mold 5. A convex spherical top plate 6 is then stacked on top. The entire mold system is placed in a vacuum forming chamber, and nitrogen gas is introduced at a rate of 5 L / min.

[0036] Simultaneously heated to the molding temperature (500±50 ℃) under nitrogen protection. Because the intermediate mold 3 is made of a material with high thermal conductivity and is relatively thin (thermal conductivity is 29.4 W / m / ℃), heat can quickly penetrate and be conducted to the upper and lower mold cavities, ensuring that the multi-layer glass preform softens synchronously and uniformly, eliminating the temperature gradient in the thickness direction. Due to the addition of the intermediate mold (3) and two layers of glass in the SAM process, the longitudinal cumulative thermal expansion is significantly increased. At this stage, the stepped upper mold 5 will be heated and lifted up, and the bottom relief fillet 52 will float up above the precision inner hole of the sleeve due to expansion, entering the flared area where the guide cone surface 41 is located. At this time, without the physical envelope of the guide cone surface, the stepped upper mold 5 is very likely to collide with the cylindrical surface of the sleeve when pressed down due to radial offset.

[0037] During the high-temperature molding stage, the press starts its downward stroke, with a downward pressure F of 10±5 KN. First, the upper die, located in the flaring zone, contacts the guide cone surface 41 at the rounded corner 52, and is forced to center under the guidance of the inclined surface, sliding into the precision inner hole of the sleeve. Subsequently, the load is transmitted downward through the convex ball top plate 6. At this time, the convex ball surface 61 at the bottom of the convex ball top plate forms point contact with the concave ball seat 51 at the top of the upper die (e.g., ...). Figure 3(As shown). Since the radius R1 (19 mm) of the convex spherical surface is smaller than the radius R2 (20 mm) of the concave spherical seat, this structure allows for radial floating compensation space for the mold assembly while achieving forced alignment of the vertical load with the mold axis center, thereby eliminating eccentric stress. The pressure is synchronously transmitted through the intermediate mold 3, causing the double-layered glass to undergo plastic flow simultaneously and completely fill the cavity.

[0038] During the decompression annealing stage, the mold cavity is kept closed, and cooling is performed slowly at a preset rate. At this time, the component begins to thermally shrink. Although the displacement direction is opposite to that during the heating stage, because precise repositioning has been achieved through the guide cone surface, the mold remains centered on the axis during the shrinkage process, avoiding mold jamming caused by uneven shrinkage.

[0039] During the cooling and demolding stage: The nitrogen gas flow rate is increased to 30 L / min for rapid cooling. Once the temperature drops to room temperature (20°C), the upper mold returns, and the nitrogen gas inlet valve is closed. During the downward reset stroke, the guide cone 41 and the clearance fillet 52 use physical interference to force correction, guiding the mold assembly into the precision guide area of ​​the sleeve, completely solving the pain points of "difficult reset and easy jamming" in multi-layer molding. Finally, the formed double-layer array lens is removed, completing the entire SAM cycle.

[0040] The key parameters of the mold system structure used in this embodiment are as follows:

[0041] Reference Figures 1 to 4 This embodiment describes a stacked array molding process (SAM) mold structure. First, in step S1, a stepped upper mold 5 is designed. A concave ball seat 51 with a radius of R2 is machined at the top axis of the upper mold. A clearance radius of R0.5 is machined on the bottom precision guide section. Initially, the depth h2 extending into the precision hole section of the sleeve is 3.5 mm. A guide cone surface 41 with a depth of 1 mm and a single-sided 30° angle is machined at the inlet of the sleeve 4. The design ensures that h1 + h2 is greater than the cumulative expansion of the system after heating, guaranteeing the continuity of dynamic correction. Vent holes 42 with an opening diameter of 2.5 mm are provided on the sidewalls of the sleeve corresponding to the two glass cavities to eliminate air tightness within the mold cavity and improve replication fidelity.

[0042] During the heating and high-temperature forming process of SAM molding, the axial displacement of the mold system mainly originates from the thermal expansion caused by the material being heated. The heating process of the glass and mold components can be approximately divided into two intervals: a solid-state heating stage and a high-temperature softening stage. The cumulative axial thermal expansion displacement can be theoretically calculated using a piecewise linear expansion model.

[0043] Under the linear approximation condition, the instantaneous linear expansion coefficient α of a material is defined as the relative elongation of the material under a unit temperature rise, and its mathematical expression is:

[0044] (1.1)

[0045] In the formula, l is the initial length of the sample, and T represents the temperature.

[0046] During the solid-state heating stage, the coefficient of linear expansion of the material can be approximated as a constant α. s The axial expansion displacement ΔL of a single layer of glass at this stage is typically provided by the glass manufacturer during factory testing. s It can be represented as:

[0047] (1.2)

[0048] Where L0 is the effective axial length of the single-layer glass preform in the mold system at room temperature (20 ℃), T0 is the initial ambient temperature, and T g This is the characteristic temperature at which the glass enters its softening state.

[0049] As the temperature continues to rise and enters the high-temperature softening stage, the glass material exhibits obvious structural relaxation characteristics, and its equivalent linear expansion behavior can be represented by the average linear expansion coefficient α. l An approximate description is provided based on test data from the glass manufacturer. The axial expansion displacement ΔL corresponding to a single layer of glass at this stage is given. l It can be represented as:

[0050] (1.3)

[0051] Among them, T p This is the peak forming temperature of the molding process.

[0052] In this embodiment, there are two glass preforms. Therefore, during the entire heating, heat preservation, and high-temperature molding process, the axial cumulative thermal expansion displacement ΔL of the mold system is... total It can be represented as:

[0053] (1.4)

[0054] Based on the above theoretical model, the design of the axial effective depth h1 of the sleeve guide cone and the depth h2 of the stepped upper die extending into the precision guide area of ​​the sleeve in the initial state must meet the following engineering criteria:

[0055] (1.5)

[0056] This ensures that the axial upward displacement of the mold assembly remains within the effective envelope of the guide cone surface under maximum thermal expansion conditions, thereby achieving stable dynamic correction and reliable reset during the subsequent downward stroke.

Claims

1. A layered arrayed molding die, characterized in that, include: Lower mold, intermediate mold, sleeve, upper mold and convex ball top plate; The sleeve is disposed on the upper side of the lower mold; at least one intermediate mold is provided inside the sleeve, which is used to divide the inner cavity of the sleeve into multiple mold cavities and conduct heat to the mold cavities above and below it; the mold cavity is used to place the glass preform, and the sleeve is provided with a sleeve exhaust hole at the position corresponding to the mold cavity, which is connected to an external vacuum auxiliary system; The upper inner wall of the sleeve is provided with a guide cone surface; the lower end of the upper mold is provided with a guide section that fits with the sleeve clearance, the lower end of the guide section is provided with a relief fillet that fits with the guide cone surface, and the top is provided with a concave ball seat; the bottom surface of the convex ball top plate is provided with a convex ball surface that fits with the concave ball seat, so that the convex ball top plate and the upper mold form a point contact when they are in axial contact. The lower mold, upper mold, and intermediate mold are respectively provided with arrayed structural cavities on their upper and lower forming surfaces, and each arrayed cavity corresponds to the other along the mold axis.

2. The stacked array molding die according to claim 1, characterized in that, The effective axial depth h1 of the guide cone surface and the depth h2 of the guide section must satisfy the following: ΔL total =nL0[a s (T g -T0)+a l (T p -T g )] Where ΔL total L0 is the axial cumulative thermal expansion displacement of the mold, L0 is the axial length of the single-layer glass preform in the mold at room temperature, T0 is the initial ambient temperature, and T g T is the characteristic temperature before glass enters its softening state. p α is the peak forming temperature of the molding process. s α is the coefficient of linear expansion of glass during the solid-state heating stage. l is the average linear expansion coefficient of the glass after the softening stage, and n is the number of glass preforms.

3. The stacked array molding die according to claim 1, characterized in that, The arrayed structural cavities are arranged regularly and equidistantly in the corresponding plane, and non-forming functional areas are provided between adjacent cavities to isolate the flow interference of glass during the molding process.

4. The stacked array molding die according to claim 1, characterized in that, The radius of the convex spherical surface is smaller than the radius of the concave spherical seat.

5. The stacked array molding die according to claim 1, characterized in that, The surface roughness of the end surfaces of the lower mold, intermediate mold, and upper mold located inside the sleeve is all below 10 nm.

6. A method for layered array molding, utilizing a layered array molding die according to any one of claims 1-5, characterized in that, include: S1. After sequentially inserting the lower mold and the first layer of glass preform, install the sleeve. Inside the sleeve, arrange the intermediate thin mold and other layers of glass preform and the stepped upper mold from bottom to top to construct the stacked space in sequence. S2. Stack a convex ball top plate with a convex spherical surface on the concave ball seat at the top of the upper mold, and use the ball head point contact to align the pressure load to the center of the mold axis. S3. Place the mold in the vacuum chamber of the single-station molding press, evacuate the vacuum, and introduce protective gas. S4. Control the molding environment to heat up to the specified temperature range, enter the heating and heat preservation stage to make the multilayer glass soften evenly. During the period when the mold floats and shifts upward due to the cumulative thermal expansion, the guide cone surface of the sleeve inlet physically envelops the avoidance rounded corners of the bottom of the stepped upper mold. S5. Entering the molding stage, during the downward molding stroke of the press, the guide cone and the avoidance fillet work together to force correction and guide the mold back to its position; then the pressure is transmitted downward through the convex ball top plate to transmit the pressure load, and the synchronous filling and forming of the multi-layer lens is achieved through the load relay effect of the intermediate mold. S6. Annealing and Cooling Demolding: After forming, depressurization annealing is performed to release internal stress. After cooling, the upper mold returns to the starting position to complete demolding.

7. The layered array molding method according to claim 6, characterized in that, The molding environment is heated to 500±50 ℃, and the pressure load is 10±5 KN.

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