A molding die structure and design method for improving product thickness uniformity

Abstract

The application discloses a mould pressing die structure and a design method for improving product thickness uniformity, and the mould pressing die structure comprises an upper die, a lower die and a cavity, and is integrated with a partition temperature control system, a composite cavity compensation system and a matrix support pressure equalization system; the partition temperature control system is used for inhibiting thermal shrinkage nonuniformity, the composite cavity compensation system is provided with a reverse geometric compensation area for offsetting deformation, and the matrix support pressure equalization system is used for balancing pressure in real time. The design method of the mould pressing die structure comprises the following steps: determining temperature control parameters, simulating and determining compensation area parameters, matching support pressure equalization system parameters, and iteratively optimizing a trial mould, so that the thickness deviation of a product is less than or equal to ±0.03 mm. The application is helpful for inhibiting elastic deformation and improving the thickness uniformity of mould pressing products.

Description

Technical Field

[0001] This invention relates to the field of compression molding technology, specifically to a compression mold structure for improving product thickness uniformity, and also to a design method for the compression mold structure. Background Technology

[0002] In the field of compression molding of SMC / BMC, rubber, plastics and high-performance composite materials, existing compression molds usually adopt temperature control methods by setting cooling channels inside the mold core to improve the stability of the molding process and thus improve the thickness uniformity. However, this type of temperature control method with cooling channels is difficult to take into account the elastic deformation control of the core, which can easily cause the actual cavity gap to deviate from the preset design value, and is insufficient to solve the problem of uneven product thickness. Summary of the Invention

[0003] The purpose of this invention is to provide a molding die structure and design method to improve the uniformity of product thickness, so as to solve the technical problems of uneven product thickness caused by uneven thermal shrinkage, cavity deformation and uneven pressure distribution in existing molding processes.

[0004] To solve the above-mentioned technical problems, the present invention specifically provides the following technical solution: A molding die structure for improving product thickness uniformity includes an upper die, a lower die, and a cavity formed by the closing of the two. The cavity has a preset base depth H. The die structure also integrates: Zoned temperature control system: including a microchannel cooling layer integrated inside the core and an intelligent temperature control module electrically connected to the microchannel cooling layer, used to suppress uneven thermal shrinkage during the molding process; Composite cavity compensation system: The working surface of the cavity is provided with a reverse geometric compensation area, which includes a cavity deepening section with a depth greater than the base depth H and / or a cavity shallowing section with a depth less than the base depth H. The cavity deepening section corresponds to the position of the product's predicted thinning area, and the cavity shallowing section corresponds to the position of the product's predicted thickening area, which is used to offset the predicted deformation during the molding process. Matrix-type support pressure equalization system: A matrix arrangement of support columns is provided below the core, and a hydraulic pressure equalization pad is embedded between the support columns and the core; the hydraulic pressure equalization pad is respectively attached to the lower surface of the core and the top of the support columns, and is used to automatically adjust the local pressure distribution to equalize the local pressure in real time; the diameter and spacing of the support columns are adapted to the force distribution of the reverse geometric compensation zone, and the two work together to maintain the pre-designed cavity depth of the reverse geometric compensation zone.

[0005] Preferably, the support column is made of high-strength alloy steel with an allowable stress ≥4000MPa, the diameter of the support column is φ110~φ130mm, the center distance between adjacent support columns is 140~192mm, which can withstand the clamping force and is not prone to plastic deformation, thus ensuring the stability of the cavity depth in the reverse geometric compensation zone.

[0006] Preferably, the hydraulic force equalizing pad includes multiple layers of high-strength steel plates, elastic seals, and interconnected hydraulic oil chambers, the hydraulic oil chambers being filled with incompressible hydraulic oil; the elastic seals are made of high-temperature resistant polyurethane or fluororubber, with a temperature range of -40℃ to 200℃.

[0007] Preferably, the channels of the microchannel cooling layer are distributed in a matrix, with a channel spacing of 8~15mm and a channel diameter of φ3~φ8mm; the intelligent temperature control module can adjust the coolant temperature and flow rate in real time, so that the temperature difference between the different zones of the cavity is ≤±1.5℃.

[0008] Preferably, the difference between the cavity deepening section and the base depth H in the reverse geometric compensation zone and the difference between the cavity shallowing section and the base depth H are both 0.1~1mm, and this difference is compatible with the predicted deformation of the product in the corresponding area.

[0009] Preferably, the upper surface of the hydraulic force equalizing pad is fitted with the lower surface of the core, and the lower surface is provided with a positioning groove adapted to the top of the support column; the top of the support column is embedded in the positioning groove to limit the radial displacement of the support column, and the support column is connected to the basic support structure of the mold by bolt fixing or welding.

[0010] Preferably, the intelligent temperature control module includes a temperature sensor and a flow regulating valve. The temperature sensor is embedded in the inner wall of the cavity and is used to collect cavity temperature data in real time and feed it back to the flow regulating valve to realize automatic adjustment of coolant flow.

[0011] Preferably, the hydraulic oil chamber of the hydraulic equalizing pad is equipped with a pressure compensation valve. When the local pressure exceeds a preset threshold, the pressure compensation valve automatically opens, and pressure equalization is achieved through the flow of hydraulic oil.

[0012] This invention also relates to a design method for a molding die structure, applied to the aforementioned molding die structure, characterized by comprising the following steps: Step 1: Based on the thermal shrinkage characteristics of the molding material, determine the channel spacing and diameter of the microchannel cooling layer in the zoned temperature control system, as well as the temperature adjustment range of the intelligent temperature control module, to ensure that the temperature difference between the cavity zones is ≤ ±1.5℃; Step 2: Based on the temperature control optimized molding simulation results, obtain the predicted thinning amount and predicted thickening amount of the product, and determine the position of the deepening section and the shallowing section of the reverse geometric compensation zone and the difference (0.1~1mm) between them and the base depth H. Step 3: Based on the simulation results of the force distribution in the reverse geometric compensation zone, match the support column diameter (φ110~φ130mm), arrangement spacing (140~192mm), and oil chamber volume and pressure response threshold of the matrix support pressure equalization system.

[0013] The design method for the molding die structure also includes an iterative optimization step: fabricating a mold sample according to the design parameters in steps 1 to 3, conducting small-batch trial molding, and measuring the actual thickness deviation of the molded product; based on the actual thickness deviation, fine-tuning the deepening / shallowing difference of the reverse geometric compensation zone, the arrangement spacing of the support columns, or the pressure response threshold of the hydraulic equalizing pad, so that the product thickness deviation is ≤ ±0.03mm.

[0014] Compared with the prior art, the present invention has the following advantages: The synergy between the microchannel cooling layer of the zoned temperature control system and the intelligent temperature control module helps to improve the problem of uneven temperature distribution in the cavity and reduce regional differences in the thermal shrinkage characteristics of the material. The preset deepening and shallowing sections are used to solve the problem that the zoned temperature control is insufficient to compensate for the uneven thermal shrinkage of the material, and the matrix support is used to solve the problem of uneven stress distribution in the mold caused by the preset deepening and shallowing sections. Attached Figure Description

[0015] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0016] Figure 1 This is a top view of the overall structure of the lower mold of the molding die structure of the present invention.

[0017] Figure 2 This is a three-dimensional structural diagram of the molding die structure of the present invention after the lower mold has hidden the core.

[0018] Figure 3 This is a top view of the mold structure of the present invention after the lower mold has concealed the core.

[0019] Figure 4 This is a schematic diagram of the cavity thickening effect of the reverse geometric compensation zone in the molding die structure of the present invention.

[0020] Figure 5This is a schematic diagram of the cavity thinning effect of the reverse geometric compensation zone in the molding die structure of the present invention.

[0021] Figure 6 This is a partial three-dimensional schematic diagram of the lower mold of the molding die structure of the present invention.

[0022] Figure 7 This is a three-dimensional structural diagram of the lower mold of the molding die structure of the present invention.

[0023] Figure 8 A flowchart illustrating the method for designing a molding die for this invention.

[0024] The labels in the diagram represent the following: 1. Lower mold; 2. Cavity; 21. Reverse geometric compensation zone; 3. Support column; 4. Hydraulic force equalizing pad; 5. Conical stop; 6. M-type pressure bearing platform; 7. Auxiliary sealing surface; 8. Zoned temperature control system. Detailed Implementation

[0025] 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.

[0026] The molding die structure of this embodiment includes an upper die, a lower die 1, and a cavity 2 formed by the two being joined together. The preset base depth H of the cavity 2 is determined according to the design thickness of the target product (for example, when the product design thickness is 5mm, H=5mm).

[0027] The mold integrates three core collaborative systems: zoned temperature control system 8, composite cavity compensation system, and matrix support pressure equalization system. Through parameter adaptation and functional collaboration, each system solves the problems of uneven thermal shrinkage, predicted deformation cancellation, and uneven pressure distribution in turn, ultimately ensuring the stability of the pre-designed depth of cavity 2.

[0028] The lower mold 1 includes key components such as the lower template, core, and basic support structure. The core is installed in the preset installation area of ​​the lower template, and the lower template provides the installation benchmark and support for the core. Its lower surface is in contact with the hydraulic pressure equalization pad 4 of the matrix support pressure equalization system to ensure the continuity of force transmission.

[0029] The zoned temperature control system 8 includes a microchannel cooling layer and an intelligent temperature control module, as detailed below: The microchannel cooling layer is integrated inside the core. The channels are distributed in a matrix pattern with a channel spacing of 12mm (within the optimized range of 8~15mm) and a channel diameter of φ5mm (within the suitable range of φ3~φ8mm). The channels are milled inside the core using machining methods, and the surface is polished after forming to reduce coolant flow resistance and avoid uneven heat dissipation caused by burrs on the inner wall of the channels.

[0030] The intelligent temperature control module includes a temperature sensor, a flow regulating valve, and a controller. The temperature sensor is a PT100 platinum resistance sensor, which is embedded in a pre-set mounting hole in the inner wall of cavity 2. The distance between the sensor probe and the working surface of cavity 2 is ≤3mm to ensure the accuracy of real-time acquisition of cavity temperature data. The flow regulating valve is an electromagnetic proportional regulating valve, which is connected in series with the liquid inlet pipe of the microchannel cooling layer. The controller receives the feedback signal from the temperature sensor to realize the automatic adjustment of the coolant flow rate.

[0031] Before compression molding, the target temperature range of the cavity is set by the controller, and the coolant (such as an industrial ethylene glycol aqueous solution) circulates in the microchannel cooling layer. During the compression molding process, the temperature sensor collects the temperature data of different areas of cavity 2 in real time. When the temperature of a certain area exceeds the set threshold, the controller drives the flow regulating valve to increase the coolant flow in the corresponding area to accelerate heat dissipation. When the temperature is lower than the threshold, the flow regulating valve reduces the flow to maintain temperature stability, and finally controls the temperature difference between the zones of cavity 2 to ≤±1.5℃, which helps to suppress uneven thermal shrinkage.

[0032] The composite cavity compensation system is a reverse geometry compensation region 21, with the following specific configuration: Cavity deepening section: For the predicted thinning area of ​​the product, a deepening structure is formed on the working surface of cavity 2 by CNC milling. The depth of the deepened cavity is H+ΔH1, where ΔH1 is 0.3mm (within the adaptation range of 0.1~1mm). The value of ΔH1 is determined by CAE simulation and is consistent with the predicted thinning amount of the product in this area. By increasing the cavity volume, the reduction in cavity volume caused by the upward arching of the mold under the action of mold closing force is offset.

[0033] Cavity Shallowing Section: For the predicted thickening area of ​​the product, a shallowing structure is formed on the working surface of cavity 2. The depth of the cavity after shallowing is H-ΔH2, where ΔH2 is 0.25mm (within the adaptation range of 0.1~1mm). The value of ΔH2 is determined by CAE simulation and matched with the predicted thickening amount of the product in this area. By reducing the cavity volume, the increase in cavity volume caused by the downward deflection of the mold is offset.

[0034] Adaptable scenarios: When the product only has a local thinning area, the reverse geometric compensation area 21 can only be set to the cavity deepening section; when the product only has a local thickening area, only the cavity shallowing section can be set; when the product has both thinning and thickening areas, both can be set simultaneously.

[0035] The machining accuracy of the reverse geometry compensation zone 21 is controlled according to the following requirements: the depth tolerance of the deepening section and the shallowing section is ±0.01mm, the surface roughness Ra≤0.8μm, to ensure the flatness of the working surface of the cavity 2, and to avoid material flow obstruction or local pressure concentration caused by machining errors.

[0036] The matrix-type support pressure equalization system mainly consists of matrix-distributed support columns 3 and hydraulic pressure equalization pads 4, and the specific implementation method is as follows: The core is fixedly installed in the installation area of ​​the lower template. The lower surface of the lower template is in contact with the upper surface of the hydraulic force equalizing pad 4. The lower surface of the hydraulic force equalizing pad 4 is in contact with the top of the support column 3. The bottom end of the support column 3 is connected to the foundation support structure of the mold by bolt fixing, forming a force transmission path of "core → lower template → hydraulic force equalizing pad → support column → foundation support structure".

[0037] The support column 3 is made of 42CrMo high-strength alloy steel. After quenching and tempering, the yield strength of this material is ≥930MPa and the allowable stress is ≥4000MPa, which meets the requirements of bearing the clamping force without plastic deformation. At the same time, this material has good fatigue strength and wear resistance, and is suitable for the long-term repeated molding conditions of the mold.

[0038] The diameter of the support column 3 is set to φ118mm (within the range of φ110~φ130mm), the center-to-center distance between adjacent support columns 3 is set to 192mm (within the range of 140~192mm), and the length of the support column 3 is determined according to the distance from the lower template to the foundation support structure to ensure that the height of the lower template and the core meets the mold closing requirements after installation.

[0039] The connecting bolts between the support column 3 and the foundation support structure are made of 12.9 grade high-strength internal hex bolts. The top end face of the support column 3 and the contact surface of the hydraulic force equalizing pad 4 are subjected to surface grinding treatment, with a flatness tolerance of ≤0.005mm, to ensure the uniformity of force transmission.

[0040] The hydraulic force equalizing pad 4 comprises three layers of stacked 42CrMo high-strength steel plates (each layer being 10mm thick), fluororubber elastic seals, and internally interconnected hydraulic oil chambers. The hydraulic oil chambers are filled with incompressible anti-wear hydraulic oil (kinematic viscosity 46mm at 40℃). 2 / s); the elastic seal is made of fluororubber, with a temperature range of -40℃ to 200℃, suitable for different working conditions such as high-temperature molding (such as SMC / BMC hot pressing) and normal-temperature molding (such as rubber cold pressing); the hydraulic oil chamber is equipped with a pressure compensation valve, and the opening threshold of the pressure compensation valve is set to 65MPa (based on the holding pressure of 60MPa in the molding process, with a certain safety margin reserved).

[0041] The lower surface of the hydraulic force equalizing pad 4 is provided with a positioning groove that matches the top of the support column 3. The diameter of the groove is 0.02 mm larger than the diameter of the top of the support column 3, and the depth is 5 mm. The top of the support column 3 is embedded in the positioning groove to limit the radial displacement of the support column 3 and prevent the support column 3 from shifting during the molding process.

[0042] During molding, the clamping force is transmitted to the material and cavity 2 through the upper mold, then to the lower mold plate through the core, and finally to the hydraulic equalizing pad 4 through the support column 3. When the pressure in a local area exceeds the opening threshold of the pressure compensation valve, the pressure compensation valve opens automatically, and the hydraulic oil flows in the hydraulic oil chamber, transferring from the high-pressure area to the low-pressure area. The steel plate of the hydraulic equalizing pad 4 corresponding to the high-pressure area undergoes slight deformation, expanding the actual bearing area and making the pressure per unit area tend to be balanced. When the pressure drops below the threshold, the pressure compensation valve closes to maintain the current pressure state, thereby balancing the local pressure in real time and working with the support column 3 to maintain the pre-designed cavity depth of the reverse geometric compensation zone 21.

[0043] The collaborative working process of the core systems is as follows: Molding preparation stage: The zoned temperature control system 8 is activated. Through the synergistic effect of the microchannel cooling layer and the intelligent temperature control module, the temperature of cavity 2 is adjusted to the set range (such as 150℃) to ensure that the zoned temperature difference is ≤±1.5℃ and to suppress uneven heat-induced shrinkage.

[0044] Mold closing stage: The upper mold descends at a set speed (e.g., 5mm / s), and the clamping force is gradually applied to ensure that cavity 2 is closed in place; during the mold closing process, precise centering and sealing are achieved through the cooperation of the mold parting surface to prevent material overflow.

[0045] During the filling and holding pressure stages: the material flows and fills the cavity 2. The composite cavity compensation system, through the deepening and shallowing sections of the reverse geometric compensation zone 21, offsets the predicted deformation caused by the material flow and the clamping force. At the same time, the matrix support pressure equalization system, through the rigid support of the support column 3 and the pressure equalization effect of the hydraulic pressure equalization pad 4, prevents the lower mold plate and core from elastically deflecting and maintains the pre-designed depth of the cavity 2. During the holding pressure process, the hydraulic pressure equalization pad 4 responds to local pressure changes in real time and achieves dynamic pressure equalization through the pressure compensation valve and the flow of hydraulic oil.

[0046] Demolding stage: After the molding is completed, the upper mold moves upward, the pressure on the composite cavity compensation system and the support pressure equalization system is released, and the zoned temperature control system continues to work until the product cools down to the set temperature, finally obtaining a molded product with uniform thickness.

[0047] To further improve mold clamping neutrality, suppress eccentric deformation, and enhance anti-overflow performance, this embodiment features a three-tiered stepped structure at the parting surface of the upper and lower molds. Extending radially from the parting surface, this structure consists of a tapered stop 5, an M-shaped pressure-bearing platform 6, and an auxiliary sealing surface 7, arranged radially from the outside to the inside to form a three-tiered stepped structure. The specific implementation is as follows: First step: The tapered stop 5 is continuously set along the outer circumference of the parting surface of the lower mold 1, forming a "lower mold convex + upper mold concave" mating structure. The lower mold side is machined with an outwardly convex tapered platform with a taper of 3° (within the optimized range of 1°~5°) and a height of 15mm. The surface roughness Ra of the outer tapered surface is ≤0.8μm after grinding. The corresponding position on the upper mold is machined with a concave tapered groove, the taper of which is consistent with the outwardly convex tapered surface of the lower mold, and the groove depth is 15mm. In the initial stage of mold closing, this guides the upper mold and lower mold 1 to accurately align, avoiding radial offset. After alignment, the radial offset is ≤0.02mm.

[0048] The second step: The M-shaped pressure-bearing platform 6 is located inside the conical stop 5, circumferentially along the parting surface. The platform width is 80mm (within the range of 50-100mm), and its height is flush with the top of the conical stop 5, with a height tolerance ≤0.01mm. The upper surface of the platform is precision ground, with a flatness tolerance ≤0.005mm. In the later stages of mold closing, it preferentially contacts the corresponding surface of the upper mold, bearing the main clamping force (accounting for over 90% of the total clamping force) and suppressing eccentric deformation of the upper and lower molds. The M-shaped pressure-bearing platform 6 adopts an M-shaped contour design with a "central bulge and gentle transitions on both sides," its shape adapting to the mold's stress characteristics. Its core advantages are as follows: Uniform transmission of clamping force: The central raised area is the main bearing surface. In the later stage of mold closing, it will first contact the corresponding surface of the upper mold and bear the core clamping force. The transition slopes on both sides can disperse the locally concentrated clamping force to the entire platform, avoid local deformation of the platform caused by pressure concentration, and ensure that the clamping force is uniformly transmitted to the lower mold 1 along the circumferential direction of the parting surface, further suppressing the eccentric deformation. Fitting precision adaptation: The transition surfaces on both sides of the M-shaped contour form a progressive "line → surface" fit with the corresponding surface of the upper mold. Combined with the platform's flatness tolerance of ≤0.005mm, it can offset the slight centering deviation during the mold closing process, increase the fitting area of ​​the upper and lower molds (≥95%), and ensure the continuity of force transmission. Optimized fatigue resistance: Compared with the planar structure, the M-type structure has a more uniform stress distribution under the same clamping force, which can reduce stress concentration at the edge of the platform. Combined with the material characteristics of 42CrMo high-strength steel plate, it can extend the long-term fatigue life of the platform and adapt to the working conditions of repeated molding.

[0049] The third step: The auxiliary sealing surface 7 is located inside the M-shaped pressure platform 6 and is connected to the edge of the cavity 2 opening. Its height is 0.5mm lower than that of the M-shaped pressure platform 6 (height difference tolerance ±0.01mm). When the M-shaped pressure platform 6 is pressed and fitted, the auxiliary sealing surface 7 fits tightly with the corresponding surface of the upper mold, forming the outer sealing structure of the cavity 2 to prevent material overflow during the molding process.

[0050] The synergistic process is as follows: During mold closing, the upper mold descends at a set speed (e.g., 5mm / s). First, the convex and concave cones of the tapered stop 5 correct the offset and achieve precise centering. As the mold closing process progresses, the M-shaped pressure-bearing platform 6 contacts the corresponding surface of the upper mold and bears the clamping force to avoid uneven load deformation. After the mold is closed, the auxiliary sealing surface 7 fits tightly to complete the sealing of the cavity 2. The three steps are connected in sequence to form a complete functional chain of "centering → pressure bearing → sealing".

[0051] The tapered stop 5, the M-type pressure platform 6, and the auxiliary sealing surface 7 are formed by CNC milling and grinding. The radial dimension tolerance of each structure is ±0.02mm. The height difference between the tapered stop 5 and the M-type pressure platform 6 is ≤0.005mm, and the height difference between the auxiliary sealing surface 7 and the former two is ±0.01mm, ensuring the structure is regular.

[0052] During assembly, the fitting clearance of the tapered stop 5 is controlled at 0.01~0.02mm to ensure alignment accuracy and avoid difficulties in mold closing; the contact area between the M-type pressure platform 6 and the corresponding surface of the upper mold is ≥95% to ensure uniform transmission of clamping force; the contact pressure between the auxiliary sealing surface 7 and the corresponding surface of the upper mold is ≥5MPa to ensure sealing and anti-overflow effect.

[0053] The molding die structure in this embodiment is applied to the molding of the top cover of an SMC material battery pack (product design thickness 5mm), and the effect is verified in the following manner: Temperature uniformity verification: During the molding process, temperature data of different areas of cavity 2 were collected by multi-point temperature sensors. The test results showed that the maximum temperature difference between different areas of the cavity was 1.2℃, which meets the requirement of ≤±1.5℃ and helps to suppress uneven thermal shrinkage.

[0054] Thickness uniformity verification: Parameters were determined according to the subsequent collaborative design method, mold samples were made and small-batch trial molding was carried out (number of trial moldings: 10 pieces). The thickness of each area of ​​the product was measured using a high-precision thickness gauge (measurement accuracy ±0.001mm). The test results showed that the thickness deviation range of the product was ±0.02mm, which met the requirement of ≤±0.03mm, and the thickness uniformity was achieved.

[0055] Structural stability verification: After 1000 consecutive molding cycles, the deformation of the support column 3 was checked. The measurement results showed that the maximum deformation was 0.01mm, with no plastic deformation. The hydraulic force equalizing pad 4 had good sealing performance and no hydraulic oil leakage. The parting surface centering accuracy and sealing effect remained stable, and the working stability of the mold met the requirements of industrial production.

[0056] Overflow prevention and anti-eccentric load verification: No material overflow occurred during the trial molding process; through the eccentric load test (applying 5% eccentric load when the mold is closed), the product thickness deviation did not increase significantly, indicating that the overall structure of the mold has good anti-eccentric load capability.

[0057] To accurately achieve the molding effect of the above-mentioned molding die structure, a corresponding molding die structure design method is required. The specific implementation steps are as follows: Step 1: Determine the parameters of the zone temperature control system First, obtain the thermal shrinkage characteristics (including thermal shrinkage rate, specific heat capacity, and thermal conductivity) of the target molding material (such as SMC material). Then, establish a mold temperature field model using ANSYS thermal simulation software. Based on this model, iteratively optimize the parameters of the microchannel cooling layer: set the initial channel spacing to 10mm and the initial channel diameter to φ4mm, and perform simulation analysis in conjunction with the temperature adjustment range (50℃~200℃) of the intelligent temperature control module. If the simulation results show that the temperature difference between the cavity partitions exceeds ±1.5℃, then reduce the channel spacing (minimum to 8mm) or increase the channel diameter (maximum to φ8mm) until the simulation results meet the requirement that the temperature difference between the cavity partitions is ≤±1.5℃. Finally, determine that the channel spacing of the microchannel cooling layer is 12mm, the channel diameter is φ5mm, and the temperature adjustment range of the intelligent temperature control module is 80℃~180℃.

[0058] Step 2: Determining the parameters of the reverse geometric compensation zone Based on the temperature control parameters determined in step 1, a clamping force load (set according to the actual clamping force of 5000kN used in production) is added to the same simulation model to perform compression molding simulation and obtain the predicted thinning amount (maximum 0.3mm) and predicted thickening amount (maximum 0.25mm) of the product. According to the simulation results, the positions of the deepening and shallowing sections of the reverse geometric compensation zone 21 are determined: the deepening section corresponds one-to-one with the predicted thinning area, and the shallowing section corresponds one-to-one with the predicted thickening area. At the same time, the difference between each area and the base depth H is determined: the difference ΔH1 of the deepening section is 0.3mm, the difference ΔH2 of the shallowing section is 0.25mm, and all differences are within the adaptation range of 0.1~1mm.

[0059] Step 3: Matching parameters of the matrix-supported pressure equalization system Using ABAQUS structural simulation software, a stress distribution model of the reverse geometric compensation zone 21 was established. The mold closing force load and compensation zone parameters from step 2 were input, and the stress distribution data (maximum local pressure 60 MPa) of the core and lower template corresponding to the compensation zone was obtained through simulation. Based on this stress data, the parameters of the support column 3 and the hydraulic force equalizing pad 4 were matched: the support column diameter was selected as φ118 mm (within the range of φ110~φ130 mm), and the center-to-center distance between adjacent support columns was set to 192 mm (within the range of 140~192 mm) to ensure that the support column could withstand the pressure in the corresponding area without plastic deformation; the oil chamber volume of the hydraulic force equalizing pad 4 was set to 500 cm³. 3 The pressure response threshold is set to 65MPa to ensure pressure balance in conjunction with the support column.

[0060] Fabricate mold samples according to the design parameters determined in steps 1-3. Select 10 pieces of molding material of the same specifications for small-batch trial molding. The trial molding process parameters are consistent with the simulation settings (clamping force 5000kN, cavity temperature 150℃, holding time 3min). After the trial molding is completed, use a high-precision thickness gauge (measurement accuracy ±0.001mm) to measure the thickness of 10 key areas of each product and record the actual thickness deviation. If the actual thickness deviation of a certain area exceeds ±0.03mm, fine-tune the parameters according to the following rules: If the deviation is "too thin", then increase the difference of the corresponding reverse geometric compensation zone deepening section (increase by 0.05mm each time, with a maximum of 1mm). If the deviation is "too thick", then increase the difference in the shallow section of the corresponding reverse geometric compensation zone (increase by 0.05mm each time, with a maximum of 1mm). If the thickness deviation in a local area repeatedly exceeds the standard, adjust the spacing of the support columns (reducing it by 10mm each time, down to a minimum of 140mm) or the pressure response threshold of the hydraulic equalizing pad (±5MPa each time). After one iteration of fine-tuning, the thickness deviation of all products was controlled within ±0.02mm, meeting the requirement of ≤±0.03mm, thus completing the design optimization.

[0061] The above embodiments are merely exemplary embodiments of this application and are not intended to limit this application. The scope of protection of this application is defined by the claims. Those skilled in the art can make various modifications or equivalent substitutions to this application within its substance and scope of protection, and such modifications or equivalent substitutions should also be considered to fall within the scope of protection of this application.

Claims

1. A molding die structure for improving product thickness uniformity, characterized in that, The mold includes an upper mold, a lower mold (1), and a cavity (2) formed by the two molds joining together. The cavity (2) has a preset base depth H. The mold structure also integrates: Zoned temperature control system (8): including a microchannel cooling layer integrated inside the core and an intelligent temperature control module electrically connected to the microchannel cooling layer, used to suppress uneven thermal shrinkage during the molding process; Composite cavity compensation system: The working surface of the cavity (2) is provided with a reverse geometric compensation area (21). The reverse geometric compensation area (21) includes a cavity deepening section with a depth greater than the base depth H and / or a cavity shallowing section with a depth less than the base depth H. The cavity deepening section corresponds to the position of the product's predicted thinning area, and the cavity shallowing section corresponds to the position of the product's predicted thickening area. It is used to offset the predicted deformation during the molding process. Matrix-type support pressure equalization system: A matrix arrangement of support columns (3) is provided below the core, and a hydraulic pressure equalization pad (4) is embedded between the support columns (3) and the core; the hydraulic pressure equalization pad (4) is respectively attached to the lower surface of the core and the top of the support column (3) to automatically adjust the local pressure distribution and equalize the local pressure in real time; the diameter and arrangement spacing of the support columns (3) are adapted to the force distribution of the reverse geometric compensation zone (21), and the two work together to maintain the pre-designed cavity depth of the reverse geometric compensation zone (21).

2. The molding die structure according to claim 1, characterized in that, The support column (3) is made of high-strength alloy steel with an allowable stress ≥4000MPa. The diameter of the support column (3) is φ110~φ130mm, and the center distance between adjacent support columns (3) is 140~192mm. It can withstand the clamping force and is not prone to plastic deformation, thus ensuring the cavity depth stability of the reverse geometric compensation area (21).

3. The molding die structure according to claim 1, characterized in that, The hydraulic force equalizing pad (4) includes multiple layers of high-strength steel plates, elastic seals and interconnected hydraulic oil chambers, the hydraulic oil chambers being filled with incompressible hydraulic oil; the elastic seals are high-temperature resistant polyurethane or fluororubber, with a temperature range of -40℃ to 200℃.

4. The molding die structure according to claim 1, characterized in that, The channels of the microchannel cooling layer are distributed in a matrix, with a channel spacing of 8~15mm and a channel diameter of φ3~φ8mm; the intelligent temperature control module can adjust the temperature and flow rate of the coolant in real time, so that the temperature difference between the partitions of the cavity (2) is ≤±1.5℃.

5. The molding die structure according to claim 1, characterized in that, The difference between the cavity deepening section and the base depth H in the reverse geometric compensation zone (21) and the difference between the cavity shallowing section and the base depth H are both 0.1~1mm. This difference is compatible with the predicted deformation of the product in the corresponding area.

6. The molding die structure according to claim 1, characterized in that, The upper surface of the hydraulic force equalizing pad (4) is in contact with the lower surface of the core, and the lower surface is provided with a positioning groove that is adapted to the top of the support column (3); the top of the support column (3) is embedded in the positioning groove to limit the radial displacement of the support column (3), and the support column (3) is connected to the basic support structure of the mold by bolt fixing or welding.

7. The molding die structure according to claim 1, characterized in that, The intelligent temperature control module includes a temperature sensor and a flow regulating valve. The temperature sensor is embedded in the inner wall of the cavity (2) and is used to collect cavity temperature data in real time and feed it back to the flow regulating valve to realize automatic adjustment of coolant flow.

8. The molding die structure according to claim 3, characterized in that, The hydraulic oil chamber of the hydraulic equalizing pad (4) is equipped with a pressure compensation valve. When the local pressure exceeds the preset threshold, the pressure compensation valve will automatically open and achieve pressure equalization through the flow of hydraulic oil.

9. A design method for a molding die structure, applied to the molding die structure described in claim 1, characterized in that, Includes the following steps: Step 1: Based on the thermal shrinkage characteristics of the molding material, determine the channel spacing and diameter of the microchannel cooling layer in the partitioned temperature control system (8), as well as the temperature adjustment range of the intelligent temperature control module, to ensure that the temperature difference between the partitions of the cavity (2) is ≤ ±1.5℃; Step 2: Based on the temperature control optimized molding simulation results, obtain the predicted thinning amount and predicted thickening amount of the product, and determine the position of the deepening section and the shallowing section of the reverse geometric compensation area (21) and the difference between them and the base depth H (0.1~1mm). Step 3: Based on the simulation results of the force distribution in the reverse geometric compensation zone (21), match the diameter (φ110~φ130mm) and spacing (140~192mm) of the support column (3) of the matrix support pressure equalization system, as well as the oil chamber volume and pressure response threshold of the hydraulic pressure equalization pad (4).

10. The design method for the molding die structure according to claim 9, characterized in that, It also includes iterative optimization step 4: make mold samples according to the design parameters of steps 1 to 3, conduct small batch trial molding, and measure the actual thickness deviation of the molded product; according to the actual thickness deviation, finely adjust the deepening / shallowing difference of the reverse geometric compensation area (21), the arrangement spacing of the support column (3), or the pressure response threshold of the hydraulic equalizing pad (4) so ​​that the product thickness deviation is ≤ ±0.03mm.

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