A large curvature PMI foam slotted hot pressing and forming method

Abstract

The present application relates to the technical field of part forming, and discloses a large-curvature PMI foam slotting hot-pressing and forming method, which comprises the following steps: collecting the mold curvature of a forming mold and the material thickness of a PMI foam plate; determining the slotting parameters of the PMI foam plate according to the mold curvature and the material thickness; setting the initial heating duration of a hot air gun according to the material thickness, and adjusting the initial heating duration according to the slotting quantity and the slotting depth; slotting the PMI foam plate according to the slotting parameters; heating and softening the slotting area by using the hot air gun based on the heating duration adjustment value, and simultaneously pressing the PMI foam plate to make each slot close, so that the PMI foam plate is attached to the surface of the forming mold; and vacuum compacting and setting the PMI foam plate attached to the surface of the forming mold. The present application realizes the collaborative matching of the PMI foam slotting parameters and the hot-pressing and forming parameters.

Description

Technical Field

[0001] This invention relates to the field of parts forming technology, and more specifically, to a method for hot pressing and forming large curvature PMI foam with grooves. Background Technology

[0002] PMI (Polymethacrylimide) foam is widely used in composite sandwich structures in aerospace, rail transportation, and high-end equipment manufacturing due to its low density, high specific strength, high temperature resistance, and excellent dielectric properties. In the manufacturing process of aircraft composite parts, PMI foam boards are typically laid on the surface of a molding die and then molded together with the composite material through vacuum bagging and curing processes to form a lightweight, high-strength sandwich structure.

[0003] For composite parts with small curvatures, PMI foam boards exhibit minimal bending deformation, making them relatively easy to form after appropriate heating. However, for composite parts with large curvatures, PMI foam boards are inherently rigid, difficult to bend at room temperature, and possess a degree of brittleness, making them prone to chipping and cracking during bending, hindering proper bonding to the molding die. Current technology typically involves cutting PMI foam boards into multiple small pieces, laying them separately, and then joining them together using adhesives to meet the molding requirements of large curvature dies. While this method improves the bonding ability of the foam boards to some extent, it increases the adhesive area, leading to increased part weight. Furthermore, excessively thick adhesive layers can cause localized surface protrusions or internal defects in the composite parts. In addition, segmented splicing requires multiple positioning, splicing, and trimming steps, resulting in a cumbersome process, high reliance on operator experience, low processing efficiency, and difficulty in guaranteeing the splicing quality between different foam blocks, easily leading to localized gaps and poor bonding, thus affecting the overall molding quality of the composite parts.

[0004] Therefore, it is necessary to provide a large-curvature PMI foam slotted hot pressing conformal molding method to solve the problem in the prior art where the segmented splicing of PMI foam boards on large-curvature molding dies affects the overall molding quality of composite material parts. Summary of the Invention

[0005] In view of this, the present invention proposes a hot-pressing molding method for large curvature PMI foam with slots, which aims to solve the problem that the segmented splicing of PMI foam boards on large curvature molding molds affects the overall molding quality of composite material parts in the prior art.

[0006] This invention proposes a method for hot-pressing and forming large-curvature PMI foam, comprising: Collect the mold curvature of the molding die and the material thickness of the PMI foam board; The grooving parameters of the PMI foam board are determined based on the mold curvature and material thickness; wherein, the grooving parameters include the number of grooves and the grooving depth; The initial heating time of the hot air gun is set according to the material thickness, and the initial heating time is adjusted according to the number of slots and the depth of slots to obtain the heating time adjustment value; The PMI foam board is grooved according to the grooving parameters; the grooved area is heated and softened using a hot air gun based on the heating time adjustment value, and the PMI foam board is pressed simultaneously to close each groove so that the PMI foam board is attached to the surface of the molding mold. The PMI foam board, which is attached to the surface of the molding die, is vacuum compacted and shaped.

[0007] Furthermore, when collecting the mold curvature of the molding die and the material thickness of the PMI foam board, the following steps are included: Obtain all the mold curvatures existing in the forming mold, and number the mold curvatures sequentially; For each numbered mold curvature, match the material thickness of the corresponding PMI foam board in the area, and store the associated information to obtain an associated storage table.

[0008] Furthermore, when determining the grooving parameters of the PMI foam board based on the mold curvature and material thickness, the following steps are included: The mold curvature and the corresponding material thickness for each mold curvature are determined based on the associated storage table. The number of slots is determined based on the curvature of the mold. The groove depth is determined based on the material thickness.

[0009] Furthermore, determining the number of slots based on the mold curvature includes: Obtain the mold curvature and the historical mold curvature of each historical forming mold in the historical mold library, filter out the historical mold curvature that is the same as the mold curvature, and record it as the target historical mold curvature; Obtain the number of historical slots corresponding to the target historical mold curvature, and determine the number of historical slots as the number of slots in the PMI foam board.

[0010] Furthermore, when determining the number of slots based on the curvature of the mold, the method further includes: When there is no historical mold curvature with the same curvature in the historical mold library, calculate the curvature similarity between the mold curvature and each historical mold curvature; The historical mold radii with the highest radii similarity are determined as the target historical mold radii; Obtain the number of historical slots corresponding to the target historical mold curvature, and determine the number of historical slots as the number of slots in the PMI foam board.

[0011] Furthermore, determining the groove depth based on the material thickness includes: The remaining thickness threshold is determined based on the material thickness: a remaining thickness percentage is preset, and the remaining thickness threshold is the product of the material thickness and the remaining thickness percentage; Calculate the thickness difference between the material thickness and the remaining thickness threshold; The thickness difference is determined as the groove depth of the PMI foam board.

[0012] Furthermore, when setting the initial heating time of the hot air gun according to the material thickness, it includes: Several thickness ranges and their corresponding heating times are preset; The thickness range corresponding to the material thickness is taken as the current thickness range, and the heating time corresponding to the current thickness range is taken as the initial heating time.

[0013] Furthermore, when adjusting the initial heating time based on the number and depth of the slots to obtain the adjusted heating time value, the following steps are included: Determine whether to adjust the initial heating time based on the groove depth; If it is determined to be an adjustment, the initial heating time is adjusted according to the number of slots and the depth of the slots.

[0014] Furthermore, when determining whether to adjust the initial heating time based on the groove depth, the following steps are included: Calculate the difference between the thickness of all the materials in the forming mold and the groove depth, and record it as the thickness difference; Calculate the average thickness difference; Whether to adjust the initial heating time is determined based on the average thickness difference: If the average thickness difference is less than a preset difference, it is determined that the initial heating time will not be adjusted; if the average thickness difference is greater than or equal to the preset difference, it is determined that the initial heating time will be adjusted.

[0015] Furthermore, if the determination is for adjustment, then when adjusting the initial heating time based on the number and depth of the slots, the following steps are included: Obtain the number and value of slots in the molding die, set an adjustment coefficient based on the number and value of slots and the average thickness difference, and adjust the initial heating time based on the adjustment coefficient; Specifically, a quantity threshold and a thickness threshold are set. If the sum of the number of slots is greater than the quantity threshold and the average thickness difference is greater than the thickness threshold, then the adjustment coefficient is the first adjustment coefficient. If the sum of the number of slots is greater than the quantity threshold and the average thickness difference is less than or equal to the thickness threshold, then the adjustment coefficient is the second adjustment coefficient. If the sum of the number of slots is less than or equal to the quantity threshold and the average thickness difference is greater than the thickness threshold, then the adjustment coefficient is the third adjustment coefficient. The formula is: 1 < third adjustment coefficient < second adjustment coefficient < first adjustment coefficient < 1.2. The heating time adjustment value is the product of the adjustment coefficient and the initial heating time.

[0016] Compared with existing technologies, the advantages of this invention are as follows: By collecting the mold curvature of the molding die and the material thickness of the PMI foam board, and determining the number of grooves, groove depth, and hot air gun heating time based on the mold curvature and material thickness, the PMI foam grooving parameters and hot pressing conformal forming parameters are synergistically matched. Grooving is performed on the PMI foam board according to the determined grooving parameters, and the grooved area is softened and pressed according to the adjusted heating time, causing each V-groove to gradually close. This allows the PMI foam board to quickly and evenly adhere to the surface of the large-curvature molding die. Finally, vacuum compaction and curing are used for shaping and solidification, improving the conformal ability of the PMI foam board to the large-curvature mold, reducing foam cracking, edge chipping, and localized voids. This avoids problems such as increased adhesive bonding, increased weight, and surface protrusions caused by traditional segmented splicing, while reducing the difficulty of manual adjustment, improving molding efficiency and quality, and ensuring the dimensional accuracy and structural stability of the composite material parts. Attached Figure Description

[0017] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1 This is a front view of a large curvature PMI foam slotted hot pressing conformal molding provided in an embodiment of the present invention; Figure 2 A side view of a large curvature PMI foam slotted hot pressing conformal molding provided in an embodiment of the present invention; Figure 3 The flowchart illustrates the high-curvature PMI foam slotting hot pressing molding method provided in this embodiment of the invention. Detailed Implementation

[0018] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the disclosure to those skilled in the art. It should be noted that, unless otherwise specified, embodiments and features in the embodiments of the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0019] In some embodiments of this application, see Figure 1-3 As shown, this embodiment provides a method for hot-pressing and forming large-curvature PMI foam, including the following steps: S100, collect the mold curvature of the molding die and the material thickness of the PMI foam board; S200. Determine the grooving parameters of the PMI foam board based on the mold curvature and material thickness; wherein, the grooving parameters include the number of grooves and the grooving depth; S300. Set the initial heating time of the hot air gun according to the material thickness, and adjust the initial heating time according to the number of slots and the slot depth to obtain the heating time adjustment value. S400. The PMI foam board is grooved according to the grooving parameters; the grooved area is heated and softened by a hot air gun based on the heating time adjustment value, and the PMI foam board is pressed simultaneously to close each groove so that the PMI foam board is attached to the surface of the molding mold. S500: Vacuum compaction and shaping of PMI foam board adhered to the surface of molding die.

[0020] Understandably, by collecting the mold curvature of the molding die and the material thickness of the PMI foam board, and determining the number of grooves, groove depth, and hot air gun heating time based on the mold curvature and material thickness, the synergistic matching of PMI foam grooving parameters and hot pressing conformal forming parameters is achieved. Grooving is performed on the PMI foam board according to the determined grooving parameters, and the grooved area is softened and pressed according to the adjusted heating time, causing each V-groove to gradually close. This allows the PMI foam board to quickly and evenly adhere to the surface of the large-curvature molding die. Finally, vacuum compaction and curing are used for shaping and solidification. This improves the conformal ability of the PMI foam board to large-curvature molds, reduces foam cracking, edge chipping, and localized voids, avoids problems such as increased adhesive bonding, increased weight, and surface protrusions caused by traditional segmented splicing, reduces the difficulty of manual adjustment, improves molding efficiency and quality, and ensures the dimensional accuracy and structural stability of composite material parts.

[0021] In some specific embodiments of this application, the process of collecting the mold curvature of the molding die and the material thickness of the PMI foam board includes: Obtain all the mold curvatures existing in the forming mold, and number the mold curvatures sequentially; For each numbered mold curvature, match the material thickness of the corresponding PMI foam board in the area, and store the associated information to obtain an associated storage table.

[0022] Understandably, by acquiring the mold curvature of each area of ​​the molding mold and numbering it sequentially, and then matching and associating the mold curvature corresponding to each number with the material thickness of the corresponding area of ​​the PMI foam board, an association storage table is established, thus realizing the one-to-one correspondence management between the mold geometric parameters and the foam material parameters.

[0023] Based on this associated storage table, the corresponding number of slots, slot depth, and subsequent heating parameters can be determined for different curvature areas of the molding die. This avoids problems such as insufficient slotting, excessive slotting depth, or uneven heating in local areas caused by using uniform parameters, thus improving the accuracy and specificity of slotting parameter determination. It provides a reliable data foundation for the subsequent large curvature conformal molding of PMI foam boards, thereby further improving the bonding effect between foam and molding die and the molding quality of composite material parts.

[0024] In some specific embodiments of this application, determining the grooving parameters of the PMI foam board based on the mold curvature and material thickness includes: The mold curvature and the corresponding material thickness for each mold curvature are determined based on the associated storage table. The number of slots is determined based on the curvature of the mold. The groove depth is determined based on the material thickness.

[0025] Understandably, by obtaining the mold curvature and material thickness corresponding to each number based on the associated storage table, and determining the number of slots based on the mold curvature and the slot depth based on the material thickness, the targeted determination of the slotting parameters of PMI foam board is achieved.

[0026] Among them, the mold curvature reflects the bending requirements of the foam board, and the material thickness reflects the structural rigidity and machining allowance of the foam board. The two are determined according to the number of slots and the slot depth, respectively. This avoids the problem of insufficient conformability or local strength reduction in different curvature areas caused by using uniform slotting parameters. It makes the slotting parameters match the mold curvature and foam thickness, which improves the hot pressing conformability of PMI foam board in large curvature areas, reduces the risk of foam edge breakage, cracking and local voids, and provides a basis for subsequent thermal softening, vacuum compaction and curing molding, thereby improving the overall molding quality and processing efficiency of composite material parts.

[0027] Specifically, determining the number of slots based on the mold curvature includes: Obtain the mold curvature and the historical mold curvature of each historical forming mold in the historical mold library, filter out the historical mold curvature that is the same as the mold curvature, and record it as the target historical mold curvature; Obtain the number of historical slots corresponding to the target historical mold curvature, and determine the number of historical slots as the number of slots in the PMI foam board.

[0028] Understandably, by obtaining the curvature of the current molding mold and matching it with the curvature of historical molds in the historical mold library, when the same mold curvature exists, the corresponding historical slotting quantity is directly called as the slotting quantity of the current PMI foam board. This fully utilizes historical molding process experience, realizes the rapid determination of slotting parameters, avoids redesigning the slotting quantity and repeatedly verifying the process for the same curvature mold each time, reduces the error caused by human experience judgment, and improves the accuracy and consistency of slotting quantity determination.

[0029] Meanwhile, since the number of historical slots has been verified in actual production to meet the conformal forming requirements of the corresponding mold curvature, it can ensure that the PMI foam board has good bending ability and structural integrity during hot pressing conformal forming, reducing the risk of foam cracking, edge breakage and local poor adhesion, and further improving the molding efficiency of large curvature PMI foam and the molding quality of composite material parts.

[0030] Furthermore, when determining the number of slots based on the curvature of the mold, the method further includes: When there is no historical mold curvature with the same curvature in the historical mold library, calculate the curvature similarity between the mold curvature and each historical mold curvature; The historical mold radii with the highest radii similarity are determined as the target historical mold radii; Obtain the number of historical slots corresponding to the target historical mold curvature, and determine the number of historical slots as the number of slots in the PMI foam board.

[0031] Understandably, when there is no historical mold curvature in the historical mold library that is exactly the same as the current mold curvature, the curvature similarity between the current mold curvature and each historical mold curvature is calculated. The historical mold curvature with the highest curvature similarity is selected as the target historical mold curvature. Then, the corresponding historical slotting quantity is used as the slotting quantity of the current PMI foam board. This can make full use of the historical process data that is closest to the current mold curvature for parameter migration. This avoids redesigning the slotting quantity and conducting multiple process tests due to the lack of completely matching historical data, shortens the process preparation cycle, and improves the efficiency of slotting parameter determination. It also ensures that the selected historical slotting quantity has high compatibility with the current mold curvature, so that the PMI foam board can still obtain good bending conformal ability in the large curvature area, reducing foam cracking, edge breakage and poor bonding problems, and improving the stability, reliability and molding quality of large curvature PMI foam hot pressing conformal molding.

[0032] Specifically, determining the groove depth based on the material thickness includes: The remaining thickness threshold is determined based on the material thickness: a remaining thickness percentage is preset, and the remaining thickness threshold is the product of the material thickness and the remaining thickness percentage; Calculate the thickness difference between the material thickness and the remaining thickness threshold; The thickness difference is determined as the groove depth of the PMI foam board.

[0033] Understandably, by determining the remaining thickness threshold based on the material thickness of the PMI foam board, calculating the remaining thickness threshold using a pre-set remaining thickness percentage, and then determining the groove depth based on the thickness difference between the material thickness and the remaining thickness threshold, an adaptive match between the groove depth and the PMI foam board thickness is achieved. This ensures that the PMI foam board has sufficient bending capacity while retaining a reasonable remaining connection thickness. This allows the foam board to smoothly close the V-groove during hot pressing and shaping, improving its ability to fit large-curvature molds. It also avoids problems such as insufficient local strength of the foam board due to excessively deep grooves, edge chipping or breakage, and excessive bending resistance and shaping difficulties due to excessively shallow grooves. Thus, it balances the shaping performance and structural integrity of the PMI foam board, improving the molding quality, processing stability, and process applicability of large-curvature composite material parts.

[0034] Specifically, the remaining thickness percentage is pre-set based on the bending conformal capability and structural integrity requirements of the PMI foam board. Through slotting conformal molding tests on PMI foam boards of different material thicknesses, and under the premise that the V-groove can close smoothly and the PMI foam board can fit into the molding mold without cracking or chipping, the remaining thickness corresponding to different material thicknesses is statistically analyzed, and the ratio of the remaining thickness to the material thickness is calculated. The ratio that meets the molding requirements is taken as the remaining thickness percentage.

[0035] In some specific embodiments of this application, setting the initial heating time of the hot air gun according to the material thickness includes: Several thickness ranges and their corresponding heating times are preset; The thickness range corresponding to the material thickness is taken as the current thickness range, and the heating time corresponding to the current thickness range is taken as the initial heating time.

[0036] Understandably, by establishing a correspondence between material thickness ranges and hot air gun heating times based on the thermal conductivity, softening properties, and conformal forming process requirements of PMI foam boards of different thicknesses, and determining the thickness range to which the PMI foam board belongs based on its material thickness, and using the corresponding heating time as the initial heating time, the hot air gun heating parameters can be quickly matched.

[0037] Because PMI foam boards of different thicknesses differ in heat capacity, thermal conductivity, and flexural stiffness, thicker PMI foam boards typically require longer heating times to soften fully, while thinner PMI foam boards require shorter heating times to avoid localized overheating. Therefore, using heating times corresponding to different thickness ranges allows the initial heating parameters to be matched to the thickness of the PMI foam board, avoiding problems such as insufficient foam softening and difficulty in conforming to shape due to insufficient heating time, or decreased foam performance, localized collapse, or even ablation due to excessive heating time.

[0038] Specifically, based on the thermal conductivity, softening properties, and conformal forming process requirements of PMI foam boards of different thicknesses, thermal softening tests are conducted on PMI foam boards of different thicknesses. In conjunction with the heating time required for the PMI foam board to reach a bendable state during the heating process, the bonding effect, and whether there are issues such as edge chipping, cracking, or localized overheating, PMI foam boards with similar thicknesses and corresponding heating times are divided into the same thickness range. The heating time that meets the conformal forming requirements is determined as the heating time corresponding to this thickness range, thereby establishing the correspondence between the material thickness range and the heating time of the hot air gun.

[0039] Because PMI foam boards of different thicknesses differ in heat capacity, thermal conductivity, and flexural stiffness, thicker PMI foam boards require longer heating times to fully soften, while thinner PMI foam boards require shorter heating times to avoid localized overheating. Therefore, by establishing a correspondence between thickness ranges and heating times, initial heating parameters can be matched to the thickness of the PMI foam board. This avoids problems such as insufficient foam softening due to insufficient heating time, making it difficult to adhere to the molding mold, or foam performance degradation, localized collapse, or even ablation due to excessive heating time.

[0040] In some specific embodiments of this application, adjusting the initial heating time based on the number of slots and the slot depth to obtain an adjusted heating time value includes: Determine whether to adjust the initial heating time based on the groove depth; If it is determined to be an adjustment, the initial heating time is adjusted according to the number of slots and the depth of the slots.

[0041] Understandably, by determining whether the initial heating time needs to be adjusted based on the groove depth, the heating parameters of the hot air gun can be adaptively adjusted.

[0042] Since the groove depth of PMI foam board directly affects the remaining thickness of the grooved area, and the remaining thickness determines the heat transfer efficiency and the bending deformation ability of the foam, when the groove is shallow, the remaining thickness is large and the overall stiffness of the foam is high. It is necessary to appropriately extend the heating time to ensure that the grooved area is fully softened, thereby improving the large curvature conformal ability of PMI foam board. When the groove is deep, the remaining thickness is small, and the foam is more easily softened by heat. In this case, maintaining the initial heating time is sufficient to meet the molding requirements, avoiding problems such as local collapse of foam, deterioration of material properties, or ablation caused by overheating.

[0043] Therefore, determining whether the initial heating time needs to be adjusted before heating can match the heating parameters of the hot air gun with the actual grooving state of the PMI foam board. This ensures the follow-forming effect while reducing the risk of overheating and provides a reliable basis for further optimizing the heating time based on the number of grooves. This improves the stability and consistency of hot pressing follow-forming of large curvature PMI foam boards and the molding quality of composite material parts.

[0044] In some specific embodiments of this application, determining whether to adjust the initial heating time based on the groove depth includes: Calculate the difference between the thickness of all the materials in the forming mold and the groove depth, and record it as the thickness difference; Calculate the average thickness difference; Whether to adjust the initial heating time is determined based on the average thickness difference: If the average thickness difference is less than a preset difference, it is determined that the initial heating time will not be adjusted; if the average thickness difference is greater than or equal to the preset difference, it is determined that the initial heating time will be adjusted.

[0045] Understandably, by calculating the thickness difference between the material thickness of the PMI foam board in each area of ​​the molding die and the corresponding groove depth, and further calculating the average of all thickness differences, the average thickness difference is used as the basis for determining whether to adjust the initial heating time, thus achieving a comprehensive assessment of the remaining thickness status of the entire molding area.

[0046] Specifically, the thickness difference reflects the remaining thickness after grooving. The greater the remaining thickness, the higher the overall rigidity of the PMI foam board and the longer it takes for heat to transfer to the bottom of the groove. If the initial heating time is still used, it is easy to cause insufficient softening of the foam, which will affect the bonding effect of the large curvature area. Conversely, when the average thickness difference is small, it means that the overall remaining thickness is thinner, and the PMI foam board is easier to complete the heat softening. At this time, there is no need to adjust the initial heating time, which can avoid local overheating of the foam, performance degradation or structural damage due to excessive heating time.

[0047] Therefore, using the average thickness difference as the basis for adjusting the heating time can comprehensively reflect the processing status of the entire PMI foam board, reduce frequent adjustments caused by local differences, improve the rationality and stability of heating parameter settings, and make the hot air gun heating process more in line with the overall conformal forming requirements of the PMI foam board, thereby improving the molding consistency, processing efficiency and molding quality of composite material parts of large curvature PMI foam boards.

[0048] Specifically, the preset difference is set in advance based on the thermal softening characteristics of PMI foam board and the requirements of the conformal forming process. PMI foam boards of different material thicknesses are selected, and hot-press conformal forming tests are conducted with different groove depths. The heating time required for the PMI foam board to reach a bendable state under different remaining thickness conditions is recorded, and a comprehensive evaluation is conducted in conjunction with the bonding effect of the foam board, whether there are edge breakage, cracking, local voids, and overheating damage.

[0049] Furthermore, when the remaining thickness increases to the point where the heating time needs to be extended to ensure that the foam board is fully softened and completes the conformal forming, the corresponding average thickness difference is determined as a preset difference. This preset difference is used as the basis for determining whether to adjust the initial heating time. When the average thickness difference reaches or exceeds the preset difference, the initial heating time is corrected; otherwise, the initial heating time remains unchanged, so that the heating parameters of the hot air gun match the actual remaining thickness of the PMI foam board after grooving, thereby improving the stability and molding quality of hot pressing conformal forming.

[0050] In some specific embodiments of this application, when adjusting the initial heating time based on the number and depth of slots as determined by the adjustment, the following steps are included: Obtain the number and value of slots in the molding die, set an adjustment coefficient based on the number and value of slots and the average thickness difference, and adjust the initial heating time based on the adjustment coefficient; Specifically, a quantity threshold and a thickness threshold are set. If the sum of the number of slots is greater than the quantity threshold and the average thickness difference is greater than the thickness threshold, then the adjustment coefficient is the first adjustment coefficient. If the sum of the number of slots is greater than the quantity threshold and the average thickness difference is less than or equal to the thickness threshold, then the adjustment coefficient is the second adjustment coefficient. If the sum of the number of slots is less than or equal to the quantity threshold and the average thickness difference is greater than the thickness threshold, then the adjustment coefficient is the third adjustment coefficient. The formula is: 1 < third adjustment coefficient < second adjustment coefficient < first adjustment coefficient < 1.2. The heating time adjustment value is the product of the adjustment coefficient and the initial heating time.

[0051] Understandably, by comprehensively considering the number of slots in the molding die and the average thickness difference of the PMI foam board after slotting, an adjustment coefficient is used to correct the initial heating time, thus achieving a coordinated match between the hot air gun heating parameters and the actual processing state of the PMI foam board.

[0052] The number of slots reflects the complexity of the conformal forming of the PMI foam board in areas of high curvature; more slots mean more areas require uniform heating. The average thickness difference reflects the remaining thickness after slotting; a larger average thickness difference indicates higher overall stiffness of the PMI foam board, requiring a longer heating time for complete softening. Therefore, by setting separate thresholds for the number of slots and thickness, and determining different adjustment coefficients based on different combinations of the number of slots and the average thickness difference, the heating time of the hot air gun can be adjusted in stages according to the actual processing requirements of the PMI foam board.

[0053] When there are many slots and the overall remaining thickness is large, the heating time should be increased appropriately to ensure that each slotted area can be fully softened; when the number of slots or the remaining thickness is low, the heating time should be reduced appropriately to avoid local overheating that could lead to a decrease in foam performance, collapse or ablation.

[0054] Furthermore, the quantity threshold, thickness threshold, and adjustment coefficient are all pre-established based on the large curvature hot pressing molding process of PMI foam board.

[0055] Specifically, PMI foam boards with different mold curvatures, different numbers of grooves, and different material thicknesses were selected for hot-press conformal forming tests. The bonding effect, softening degree, edge chipping, cracking, and local overheating of PMI foam boards under each test condition were statistically analyzed. Combined with the average number of grooves and the average thickness difference corresponding to achieving good conformal forming effect, the number of grooves was graded to determine the quantity threshold, and the average thickness difference was graded to determine the thickness threshold. Subsequently, under each grade combination, with the goal of enabling PMI foam boards to soften sufficiently without overheating damage, the initial heating time was gradually modified to determine the corresponding adjustment coefficient, and the correspondence between the groove number grade, the average thickness difference grade, and the adjustment coefficient was established.

[0056] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program goods. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program goods embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0057] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program goods according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0058] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0059] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for hot-pressing and molding large-curvature PMI foam, characterized in that, include: Collect the mold curvature of the molding die and the material thickness of the PMI foam board; The grooving parameters of the PMI foam board are determined based on the mold curvature and material thickness; wherein, the grooving parameters include the number of grooves and the grooving depth; The initial heating time of the hot air gun is set according to the material thickness, and the initial heating time is adjusted according to the number of slots and the depth of slots to obtain the heating time adjustment value; The PMI foam board is grooved according to the grooving parameters; the grooved area is heated and softened using a hot air gun based on the heating time adjustment value, and the PMI foam board is pressed simultaneously to close each groove so that the PMI foam board is attached to the surface of the molding mold. The PMI foam board, which is attached to the surface of the molding die, is vacuum compacted and shaped.

2. The method for hot-pressing and forming large-curvature PMI foam with slotting according to claim 1, characterized in that, When collecting the mold curvature of the molding die and the material thickness of the PMI foam board, the following is included: Obtain all the mold curvatures existing in the forming mold, and number the mold curvatures sequentially; For each numbered mold curvature, match the material thickness of the corresponding PMI foam board in the area, and store the associated information to obtain an associated storage table.

3. The method for forming large-curvature PMI foam by slotting and hot pressing according to claim 2, characterized in that, Determining the grooving parameters of the PMI foam board based on the mold curvature and material thickness includes: The mold curvature and the corresponding material thickness for each mold curvature are determined based on the associated storage table. The number of slots is determined based on the curvature of the mold. The groove depth is determined based on the material thickness.

4. The method for forming large-curvature PMI foam by slotting and hot pressing according to claim 3, characterized in that, Determining the number of slots based on the curvature of the mold includes: Obtain the mold curvature and the historical mold curvature of each historical forming mold in the historical mold library, filter out the historical mold curvature that is the same as the mold curvature, and record it as the target historical mold curvature; Obtain the number of historical slots corresponding to the target historical mold curvature, and determine the number of historical slots as the number of slots in the PMI foam board.

5. The method for hot-pressing and forming large-curvature PMI foam with slotting according to claim 4, characterized in that, When determining the number of slots based on the curvature of the mold, the method further includes: When there is no historical mold curvature with the same curvature in the historical mold library, calculate the curvature similarity between the mold curvature and each historical mold curvature; The historical mold radii with the highest radii similarity are determined as the target historical mold radii; Obtain the number of historical slots corresponding to the target historical mold curvature, and determine the number of historical slots as the number of slots in the PMI foam board.

6. The method for hot-pressing and forming large-curvature PMI foam with slotting according to claim 3, characterized in that, Determining the groove depth based on the material thickness includes: The remaining thickness threshold is determined based on the material thickness: a remaining thickness percentage is preset, and the remaining thickness threshold is the product of the material thickness and the remaining thickness percentage; Calculate the thickness difference between the material thickness and the remaining thickness threshold; The thickness difference is determined as the groove depth of the PMI foam board.

7. The method for hot-pressing and forming large-curvature PMI foam with slotting according to claim 6, characterized in that, Setting the initial heating time of the hot air gun according to the material thickness includes: Several thickness ranges and their corresponding heating times are preset; The thickness range corresponding to the material thickness is taken as the current thickness range, and the heating time corresponding to the current thickness range is taken as the initial heating time.

8. The method for hot-pressing and forming large-curvature PMI foam with slotting according to claim 7, characterized in that, When adjusting the initial heating time based on the number and depth of slots to obtain an adjusted heating time value, the following steps are included: Determine whether to adjust the initial heating time based on the groove depth; If it is determined to be an adjustment, the initial heating time is adjusted according to the number of slots and the depth of the slots.

9. The method for hot-pressing and forming large-curvature PMI foam with slotting according to claim 8, characterized in that, When determining whether to adjust the initial heating time based on the groove depth, the following steps are included: Calculate the difference between the thickness of all the materials in the forming mold and the groove depth, and record it as the thickness difference; Calculate the average thickness difference; Whether to adjust the initial heating time is determined based on the average thickness difference: If the average thickness difference is less than a preset difference, it is determined that the initial heating time will not be adjusted; if the average thickness difference is greater than or equal to the preset difference, it is determined that the initial heating time will be adjusted.

10. The method for forming large-curvature PMI foam by slotting and hot pressing according to claim 9, characterized in that, If the determination is for adjustment, then when adjusting the initial heating time according to the number of slots and the slot depth, the following is included: Obtain the number and value of slots in the molding die, set an adjustment coefficient based on the number and value of slots and the average thickness difference, and adjust the initial heating time based on the adjustment coefficient; Specifically, a quantity threshold and a thickness threshold are set. If the sum of the number of slots is greater than the quantity threshold and the average thickness difference is greater than the thickness threshold, then the adjustment coefficient is the first adjustment coefficient. If the sum of the number of slots is greater than the quantity threshold and the average thickness difference is less than or equal to the thickness threshold, then the adjustment coefficient is the second adjustment coefficient. If the sum of the number of slots is less than or equal to the quantity threshold and the average thickness difference is greater than the thickness threshold, then the adjustment coefficient is the third adjustment coefficient. The formula is: 1 < third adjustment coefficient < second adjustment coefficient < first adjustment coefficient < 1.

2. The heating time adjustment value is the product of the adjustment coefficient and the initial heating time.

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