A design method for a mold for curing molding of a reflector and a manufacturing method of the reflector

Abstract

The present application aims to provide a design method for a reflector curing forming mold and a manufacturing method of the reflector. The present application utilizes the curing force field of a reflecting panel induced by the mismatch of the thermal expansion coefficients of the reflecting panel and the mold during the curing forming process of the reflecting panel on the mold, and applies the curing force field to the reflecting panel of the overall structure of the assembled reflector to obtain the geometric shape of the reflecting panel at this time, and to obtain the geometric shape of the forming working surface of the curing forming mold. Further, the present application can further obtain the geometric shape of the forming working surface of the curing forming mold through multiple updating iterations, so that the difference between the geometric shape of the reflecting panel of the cured reflector and the theoretical design geometric shape thereof is reduced or even eliminated during the manufacturing process of the reflector, and the geometric precision of the reflector is improved.

Description

Technical Field

[0001] This invention relates to the technical field of aerospace reflectors, and in particular to a design method for a mold used for curing and molding a reflector and a manufacturing method for the reflector. Background Technology

[0002] Carbon fiber reinforced resin matrix composites have been widely used in aerospace and other fields due to their unique advantages, including high specific strength and specific stiffness, strong designability, good fatigue fracture resistance, corrosion resistance, good structural dimensional stability, and ease of large-area integral molding. Autoclave molding technology enables sequential and real-time online control of process parameters such as temperature, pressure, and vacuum, and is therefore widely used in the molding of high-tech composite material components in aerospace, electronics, weaponry, transportation, and new energy industries.

[0003] Composite material parts are molded using autoclaves. The molding die, along with the composite material part, is placed in a vacuum autoclave at high temperature and pressure to cure the composite material. The quality and precision of the cured composite material part are directly determined by the curing die. Generally, considering cost and machinability, curing dies for composite material parts are made of metal materials such as cast iron or Invar. However, there is a difference in the coefficients of thermal expansion between the metal curing die and the composite material part. For example, the coefficient of thermal expansion of a cast iron die is an order of magnitude larger than that of the composite material part. Therefore, this inconsistency in the coefficients of thermal expansion between the curing die and the composite material part leads to non-uniform curing stress and structural deformation during the curing process. Consequently, the geometry of the final molded composite material part differs from the theoretically designed geometry.

[0004] Currently, mold design methods for composite material parts only consider the geometric design of thermal deformation during the curing process. Therefore, the reflector panels of reflectors made using molds obtained by such methods still have certain differences from the theoretical design and are difficult to meet the working accuracy requirements of high-precision reflectors. Summary of the Invention

[0005] To overcome the aforementioned technical deficiencies, the present invention aims to provide a method for manufacturing a reflector and a method for designing a mold for curing the reflector. The present invention utilizes the curing force field induced by the mismatch in the thermal expansion coefficients of the reflector panel and the mold during the curing process on the reflector panel. This force field is applied to the reflector panel of the assembled reflector structure to obtain the geometry of the reflector panel at this point, and thus obtains a suitable geometry for the molding working surface of the curing mold. Furthermore, the present invention can further refine the geometry of the molding working surface of the curing mold through multiple iterations, thereby reducing or even eliminating the difference between the geometry of the curing reflector panel and its theoretically designed geometry during the reflector manufacturing process, improving the geometric accuracy of the reflector panel.

[0006] This invention discloses a method for designing a mold for curing and molding a reflector, which includes the following steps:

[0007] a. Based on the theoretical geometry G of the reflector's reflective panel design R Establish the initial geometric model of the mold and the initial geometric model of the reflective panel, wherein the reflective panel is placed on the mold, and the initial geometric shape G0 of the forming working surface of the mold is... M With the initial geometry G0 of the reflective panel R same;

[0008] b. Heat the uncured reflective panel and the mold together from room temperature T0 to curing temperature T1 to obtain the geometry G1 of the reflective panel. R ;

[0009] c. Update the physical parameters of the reflective panel, causing the reflective panel and mold to cool together from the curing temperature T1 to room temperature T0, thus obtaining the geometry G2 of the reflective panel. R ;

[0010] d. The reflective panel, which is heated from room temperature T0 to curing temperature T1 along with the mold, is cooled from curing temperature T1 to room temperature T0 without the mold, to obtain the geometry G2 of the reflective panel. RF ;

[0011] e. Based on geometry G2 RF and geometry G2 R To obtain the curing force field of the reflective panel induced during the cooling process;

[0012] f. Assemble the back rib structure on the reflective panel to form an assembled reflector;

[0013] g. Apply a curing force field to the reflective panel of the assembled reflector to obtain the geometry G3 of the reflective panel. R ,

[0014] h, in geometric shape G0 M -G3 R +G design R The geometry of the molding working surface of the mold is used to prepare the reflector curing molding mold.

[0015] In some embodiments, step h in the above-described curing and molding method further includes h. obtaining the geometry G3 of the reflective panel. R With respect to the theoretical geometry G of the reflective panel design R error value 0 ε RMS and compare 0 ε RMS With a threshold i.when Then the initial geometry G0 of the forming working surface of the mold is used. M The geometry of the molding working surface of the mold is used to prepare the reflector curing molding mold; when Then update the initial geometry of the working surface of the solidification molding die to G0. M -G3 R +G design R And continue with step ai.

[0016] In some embodiments, in the above-described curing and molding method, according to the geometry G2 RF and geometry G2 R The steps for obtaining the curing force field of the reflective panel induced during the cooling process include: according to the geometry G2 RF and geometry G2 R Obtain the forced displacement field {ΔU} of the reflective panel. GH According to the forced displacement field {ΔU} GH}, obtain the curing force field {F} of the reflective panel. GH}

[0017] In some embodiments, in the above curing and molding method, in step c, based on the thermal expansion coefficient α of the reflective panel... R and elastic modulus E R Obtain the geometry G2 R In step d, based on the thermal expansion coefficient α of the reflective panel... R and elastic modulus E R Obtain the geometry G2 RF The coefficient of thermal expansion α of the reflective panel is...R and elastic modulus E R Both change with temperature, and their ratio changes either linearly or nonlinearly.

[0018] Another aspect of the present invention discloses a method for manufacturing a reflector, which includes the following steps:

[0019] Mold design: Design and prepare a solidified mold according to the design method described above;

[0020] Lay-up: Lay the prepreg sheet of the reflective panel onto the mold surface;

[0021] Curing and molding; heating the mold with the reflective panel to the curing temperature T1;

[0022] Cooling: Cool the mold with the reflective panel from the curing temperature T1 to room temperature T0;

[0023] Assemble the back rib structure: Install the back rib structure of the reflector on the back of the reflector panel that has been cured but not demolded to obtain the assembled reflector;

[0024] Demolding: Removing the assembled reflector from the mold.

[0025] In some embodiments, the manufacturing method further includes attaching the back rib structure to the back of the reflective panel by adhesive bonding.

[0026] Compared with existing technologies, the above technical solution has the following advantages:

[0027] 1. By utilizing the process of simulating the curing and molding of a reflective panel on a mold, the geometry of the mold forming working surface is continuously corrected. This method is easy to implement and yields accurate results.

[0028] 2. Fully consider the influence of mold constraint force on the final geometry of the reflector after demolding during the curing process of the reflector panel, and accurately compensate for the geometry of the reflector panel of the final formed reflector;

[0029] 3. By reducing or even eliminating the difference between the geometry of the solidified reflective panel and its theoretical geometry, the working accuracy of the manufactured reflector is ultimately improved;

[0030] 4. The manufacturing process of assembling first and then demolding is adopted, which further reduces the impact of the reflective panel rebound on the final working accuracy of the reflector during the demolding process. Attached Figure Description

[0031] Figure 1 A schematic flowchart illustrating a design method for a mold for curing a reflector according to a preferred embodiment of the present invention;

[0032] Figure 2 is a schematic flowchart of a method for manufacturing a reflector according to a preferred embodiment of the present invention, wherein...

[0033] Figure 2a The reflective panel layup process is shown;

[0034] Figure 2b The heating and curing process of the reflective panel is shown;

[0035] Figure 2c The cooling process of the reflective panel is shown;

[0036] Figure 2d The installation process of the back brace is shown;

[0037] Figure 2e The demolding process of the entire reflector is shown. Detailed Implementation

[0038] The advantages of the present invention will be further illustrated below with reference to the accompanying drawings and specific embodiments.

[0039] In practical applications, the surface geometry of the reflector panel has a significant impact on the reflector's working accuracy. During the reflector manufacturing process, differences in materials between the reflector panel and the mold result in different coefficients of thermal expansion. Therefore, after the reflector is cured and demolded, the geometry of the reflector panel will differ from its theoretically designed geometry, thus affecting the reflector's working accuracy. To address this problem, this invention proposes a mold design method that, based on iterative updates to the mold's forming surface, reduces or even eliminates the difference between the geometry of the cured reflector panel and its theoretically designed geometry. Specific embodiments and accompanying drawings are provided below, for example... Figure 1 This invention provides a detailed explanation of the main steps and advantages of the design method for the mold used in the curing and molding of reflectors.

[0040] The mold design method in the following embodiments can be implemented based on mature 3D modeling software, finite element analysis software, or a self-compiled program.

[0041] Example 1

[0042] - Establish the initial geometric model of the mold and reflective panel.

[0043] In the mold used for curing and molding the reflective panel of a reflector, the molding working surface of the mold refers to the curved surface of the part where the mold and the reflective panel are joined. In this embodiment, the theoretical geometry G of the reflective panel can be used as the molding surface. design R The initial geometry of the molding working surface of the mold 120 used for curing the reflective panel is set as follows: Generally, the initial geometry of the forming working surface of the mold can be equal to the theoretical geometry G of the reflective panel. design R Of course, depending on the needs of the actual application, those skilled in the art can also design the geometry based on the theory of the reflective panel and set the initial geometry of the forming working surface of the mold to other required geometry.

[0044] To facilitate explanation of the invention, in this embodiment, the initial geometry G0 of the molding working surface of the mold 120 for curing the reflective panel is described. M The theoretical geometry G of the reflector's reflective panel is equal to that of the reflector. design R The example provided is for illustration only and should not be construed as limiting the achievable embodiments of the present invention. It only includes the initial geometry G0 of the molding working surface of the mold 120 for curing the reflective panel. M The theoretical geometry G of the reflector's reflective panel is equal to that of the reflector. design R This is one such situation.

[0045] Furthermore, in this embodiment, the theoretical geometry G of the reflective panel can also be used as a reference. design R The initial geometry of the reflective panel 100, set at room temperature T0 and before curing, is as follows: In this embodiment, the initial geometry of the reflective panel 100 is made consistent with the initial geometry of the molding working surface of the mold. That is:

[0046]

[0047] - Obtain the geometry of the reflective panel after heat curing.

[0048] The uncured reflective panel and its curing mold are heated together from room temperature T0 to the curing temperature T1 of the composite material used to manufacture the reflective panel, thereby obtaining the geometry of the cured reflective panel 101. At this point, after being heated and cured, the reflective panel is in a cured state at curing temperature T1, and the geometry of the cured reflective panel 101 is... It can be obtained from the following formula:

[0049]

[0050] in, This indicates the amount of thermal deformation of the reflective panel during the heating and curing process.

[0051] During the curing process, the reflective panel is deformed by the curing mold 121. Therefore, the amount of thermal deformation of the reflective panel during the curing process is the same as the amount of thermal deformation of the curing mold.

[0052]

[0053] in, Obtained from function f1. α M The coefficient of thermal expansion of the mold is represented; ΔT1 = T1 - T0 is the temperature change; L0 represents the geometrical correlation of the reflective panel 100 before curing at room temperature T0; [K M ] represents the stiffness matrix of the mold.

[0054] Furthermore, in this embodiment, the physical parameters of the uncured reflective panel can be set to the physical parameters of the composite prepreg to obtain the geometry of the cured reflective panel 101. - Obtain the geometry of the reflective panel after it has cured and cooled.

[0055] After curing at elevated temperatures, the physical parameters of the reflective panel are updated. The physical parameters of the composite material plate, obtained experimentally as a function of temperature, are then updated into the analysis model. The reflective panel and mold are cooled together from the curing temperature T1 to room temperature T0, resulting in the following geometry of the cured and undemolded reflective panel 102: At this point, the reflective panel has completed its curing and molding. During the cooling process, the reflective panel does not detach from the mold; it remains mutually constrained with the curing mold 122. Therefore, the geometry of the cured and undemolded reflective panel 102 remains unchanged. It can be obtained from the following formula:

[0056]

[0057] in, This represents the amount of thermal deformation of the reflective panel after it and its curing mold have cooled together. At this point, due to the mutual constraint between the reflective panel and its curing mold, the amount of thermal deformation of the reflective panel can be obtained by the following formula:

[0058]

[0059] in, Obtained from function f2. α M With α R The coefficients of thermal expansion of the curing mold and the reflective panel are respectively represented; ΔT2=T0-T1 is the temperature change; L1 represents the geometrical correlation of the cured reflective panel 101 at curing temperature T1; [K M ] and [K RLet represent the stiffness matrix of the mold and the stiffness matrix of the solidified reflective panel, respectively. During this cooling process, the coefficient of thermal expansion α of the solidified reflective panel is... R It varies with temperature, and its variation can be linear or nonlinear. During this cooling process, the stiffness matrix [K] of the solidified reflective panel... R The elastic modulus E of the solidified reflective panel R Related. During this cooling process, the elastic modulus E of the solidified reflective panel... R It also changes with temperature, and its ratio change can be linear or nonlinear.

[0060] - Obtain the geometry of the reflective panel after it has been heated and cured, and then removed from the mold, as it has cooled freely.

[0061] After the reflective panel and mold have both undergone heating and curing, assuming the reflective panel is detached from the mold, the physical parameters of the composite material plate as a function of temperature obtained from the experiment can be updated into the analysis model. This allows the reflective panel to cool to room temperature T0 independently in a free state without the forced constraint of the mold, thus obtaining the geometry of the freely cooling reflective panel. It can be represented as:

[0062]

[0063] in, This represents the amount of thermal deformation of the reflective panel in its free state as it cools from the curing temperature T1 to room temperature T0, which can be obtained by the following formula:

[0064]

[0065] in, Obtained from function f3. α R The coefficient of thermal expansion of the reflective panel is represented by ΔT2 = T0 - T1, which is the temperature change. L1 represents the geometrical correlation of the cured reflective panel 101 at curing temperature T1. [K] R [] represents the stiffness matrix of the solidified reflective panel. Wherein, during this cooling process, the coefficient of thermal expansion α of the solidified reflective panel... R It varies with temperature, and its variation can be linear or nonlinear. During this cooling process, the stiffness matrix [K] of the solidified reflective panel... R The elastic modulus E of the solidified reflective panel R Related. During this cooling process, the elastic modulus E of the solidified reflective panel... R It also changes with temperature, and its ratio change can be linear or nonlinear.

[0066] - Obtain the curing force field of the reflective panel induced during the cooling process.

[0067] When freed from the constraints of the mold, the geometry of the freely cooling reflective panel 103 is as follows: The geometry of the reflective panel 102 after curing and before demolding is as follows: When the reflective panel and its curing mold are cooled together in an autoclave, due to the forced constraint between them, the cured reflective panel, under the forced action of an external force field, undergoes a change in its geometric shape. Deformed into geometry This forced force field is the curing force field of the reflective panel induced by the mismatch between the thermal expansion coefficients of the reflective panel and its curing mold.

[0068] Therefore, in the geometry of the freely cooling reflective panel 103 Apply a forced displacement field: {ΔU} GH}, allowing the geometry of the freely cooling reflective panel 103 to deform into the geometry of the solidified and undemolded reflective panel 102. Wherein, {ΔU GH The specific value is:

[0069]

[0070] Then, through inverse kinematics calculations, the constraint force field between the reflective panel and the mold during the above curing and cooling processes is obtained, which is the curing force field {F} of the reflective panel. GH The specific calculation formula is as follows:

[0071] {F GH}=[K RF ]·{ΔU GH}

[0072] Among them, [K RF [ ] represents the stiffness matrix of the freely cooling reflective panel 103.

[0073] - Obtain the geometry of the reflective panel after demolding the reflector.

[0074] The curing method of the integral reflector in this embodiment is further characterized in that, after the reflective panel of the reflector has been cured and before demolding, a back rib structure, namely the back rib structure 140, is installed on the geometry of the reflective panel 102. Therefore, here, the curing force field {F} of the reflective panel obtained in the above steps is used to... GH The reverse application is applied to the integral reflector 150 before demolding, that is, to the reflective panel 102 with the back rib structure 140 installed, thereby obtaining the geometry of the reflective panel 104 after the reflector has been cured and demolded. Specifically, it is expressed as follows:

[0075]

[0076] Among them, [K REF [ ] represents the stiffness matrix of the overall reflector 105 before demolding.

[0077] The geometry of the reflector panel 104 after curing and demolding This refers to the geometry of the reflective panel in its final, stress-free state after curing.

[0078] - Obtain the geometry of the mold forming working surface for use in preparing the reflector curing mold.

[0079] Based on the above considerations of factors such as the curing force field on the reflective panel caused by the difference in thermal expansion coefficients between the mold and the reflective panel, the obtained geometric shape of the reflective panel after demolding can be set to geometry G0. M -G3 R +G design R The geometry of the molding working surface of the mold is used to prepare the reflector curing mold. The reflector prepared by this mold can reduce or even eliminate the difference between the geometry of the reflector panel of the curing reflector and its theoretically designed geometry, thereby improving the working accuracy of the reflector.

[0080] In some embodiments of the present invention, based on the method steps described in the above embodiments, the curing mold of the reflector is updated and iterated to further reduce or even eliminate the difference between the geometry of the reflective panel of the cured reflector and its theoretically designed geometry. Specifically, this includes the following steps:

[0081] Set a convergence error threshold for the iterative calculation of a solidified molding die update. This refers to the target RMS error between the geometry of the reflective panel after final demolding and the theoretical geometry of the reflective panel. Therefore, based on the mold design method of the above embodiment, the geometry of the demolded reflective panel 104 obtained according to this design method is compared with the theoretically designed geometry of the reflective panel to obtain its RMS error value. 0 ε RMS .

[0082] if Then stop the update and iteration calculation of the reflective panel curing mold, and set the initial geometry G0 of the curing working surface of the curing mold to the current state. M The geometry of the working surface of the reflector panel curing mold 120 is used to prepare the reflector curing mold.

[0083] if The initial geometry of the working surface of the curing mold for the reflector panel of the updated reflector is G0. M -G3 R +G design R And continue with the corresponding steps in the above embodiments.

[0084] In summary, the mold design method provided by this invention utilizes the curing force field induced by the mismatch in thermal expansion coefficients between the reflective panel and the mold during the curing process of the reflective panel on the mold. This force field is then applied to the reflective panel of the assembled reflector structure to obtain the geometry of the reflective panel at this point. This geometry, in turn, yields a suitable geometry for the molding working surface of the curing mold. Furthermore, this invention can further refine the geometry of the molding working surface of the curing mold through multiple iterations, thereby reducing or even eliminating the difference between the geometry of the curing reflector panel and its theoretically designed geometry during the reflector manufacturing process, thus improving the geometric accuracy of the reflector panel.

[0085] Another aspect of the present invention provides a method for manufacturing a reflector, which employs a method of first assembling the back rib structure and then demolding it. Combined with the mold designed in the above embodiments, this significantly improves the geometric accuracy of the reflective panel of the final molded reflector, and thus may include the following steps (such as...). Figures 2a-2e As shown):

[0086] - Mold design: Design the mold according to the design methods described in the above embodiments;

[0087] - Lay-up: Lay the impregnated material pieces of the reflective panel onto the mold surface;

[0088] At room temperature (T0), the prepreg sheet of the reflector panel for making the reflector is laid on the surface of the molding working surface of the curing mold according to the design.

[0089] - Curing and molding; heating the mold with the reflective panel to the curing temperature T1;

[0090] The reflective panel is cured and molded by using an autoclave curing process. The mold with the reflective panel is heated to the curing temperature T1 to complete the curing and molding of the reflective panel.

[0091] - Cooling: Cool the mold with the reflective panel from the curing temperature T1 to room temperature T0;

[0092] After the reflective panel is cured and molded, it is cooled from the curing temperature T1 to room temperature T0 in an autoclave.

[0093] -Assembly backing structure: A backing structure for installing the reflector on the back of the cured but not yet demolded reflective panel.

[0094] The assembled reflector is obtained;

[0095] At room temperature (T0), the back ribs are installed onto the back of the cured but not yet demolded reflective panel. Preferably, the back ribs are installed onto the back of the reflective panel by room temperature bonding. Preferably, the reflector of the present invention also includes other accessory structures that can provide back support, which are also assembled onto the reflector when the reflective panel is cured but not yet demolded.

[0096] - Demolding: The assembled reflector structure is detached from the mold.

[0097] After the final reflector structure is removed from the mold, the bonded and cured reflector structure springs back to its final geometric shape. According to the method of this embodiment, the geometric shape of the reflector panel of the final reflector has virtually no error or very small error compared with the theoretical geometric shape of the reflector panel, thus improving the working accuracy of the reflector.

[0098] It should be noted that the embodiments of the present invention have better implementability and are not intended to limit the present invention in any way. Any person skilled in the art may use the above-disclosed technical content to change or modify it into equivalent effective embodiments. However, any modifications or equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A method for designing a curing mold for a reflector, characterized in that, Includes the following steps: a. Based on the theoretical geometry G of the reflector's reflective panel design R Establish the initial geometric model of the mold and the initial geometric model of the reflective panel, wherein the reflective panel is placed on the mold, and the initial geometric shape G0 of the forming working surface of the mold is... M With the initial geometry G0 of the reflective panel R same; b. The uncured reflective panel and the mold are heated together from room temperature T0 to curing temperature T1 to obtain the geometry G1 of the reflective panel. R ; c. Update the physical parameters of the reflective panel, causing both the reflective panel and the mold to cool together from the curing temperature T1 to room temperature T0, thereby obtaining the geometry G2 of the reflective panel. R ; d. The reflective panel, which has been heated from room temperature T0 to curing temperature T1 along with the mold, is cooled from curing temperature T1 to room temperature T0 without the mold, to obtain the geometry G2 of the reflective panel. RF ; e. Based on geometry G2 RF and geometry G2 R To obtain the curing force field of the reflective panel induced during the cooling process; f. Assemble the back rib structure on the reflective panel to form an assembled reflector; g. Apply a curing force field to the reflective panel of the assembled reflector to obtain the geometry G3 of the reflective panel. R , h, in geometric shape G0 M -G3 R +G design R The geometry of the molding working surface of the mold is used to prepare the reflector curing molding mold.

2. The design method as described in claim 1, characterized in that, Step h also includes, h. Obtain the geometry G3 of the reflective panel. R With respect to the theoretical geometry G of the reflective panel design R error value and compare With a threshold , i. when Then, the initial geometry of the molding working surface of the solidification mold is updated to G0. M -G3 R +G design R And continue with step ai.

3. The design method as described in claim 1, characterized in that, According to geometry G2 RF and geometry G2 R The steps for obtaining the curing force field of the reflective panel induced during the cooling process include: According to geometry G2 RF and geometry G2 R Obtain the forced displacement field of the reflective panel. , According to the forced displacement field Obtain the curing force field of the reflective panel. .

4. The design method as described in claim 1, characterized in that, In step c, based on the thermal expansion coefficient of the reflective panel... and elastic modulus Obtain the geometry G2 R ; In step d, based on the thermal expansion coefficient of the reflective panel... and elastic modulus Obtain the geometry G2 RF The coefficient of thermal expansion of the reflective panel is... and elastic modulus Both change with temperature, and their ratio changes either linearly or nonlinearly.

5. A method for manufacturing a reflector, characterized in that, Includes the following steps: Mold design: Design and prepare a solidified mold according to the design method described in any one of claims 1-4; Lay-up: Lay the prepreg sheet of the reflective panel onto the mold surface; Curing and molding; heating the mold with the reflective panel to the curing temperature T1; Cooling: Cool the mold with the reflective panel from the curing temperature T1 to room temperature T0; Assemble the back rib structure: Install the back rib structure of the reflector on the back of the reflector panel that has been cured but not demolded to obtain the assembled reflector; Demolding: Removing the assembled reflector from the mold.

6. The manufacturing method as described in claim 5, characterized in that, The back rib structure is installed on the back of the reflector panel by adhesive bonding.

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